JP5556499B2 - Two-stage boost refrigeration cycle - Google Patents

Description

  The present invention relates to a two-stage boosting type refrigeration cycle that includes a low-stage compression mechanism and a high-stage compression mechanism and is capable of boosting refrigerant in multiple stages.

  Conventionally, in Patent Document 1, a low-stage side compression mechanism that compresses and discharges low-pressure refrigerant until it becomes intermediate-pressure refrigerant, and an intermediate-pressure refrigerant discharged from the low-stage side compression mechanism is compressed and discharged until it becomes high-pressure refrigerant. There is disclosed a two-stage boosting type refrigeration cycle that includes a high-stage compression mechanism configured to increase the pressure of refrigerant in multiple stages.

  Furthermore, the two-stage boosting type refrigeration cycle of Patent Document 1 is applied to an air conditioner, and heats the indoor blowing air by exchanging heat between the high-temperature and high-pressure refrigerant discharged from the high-stage compression mechanism and the indoor blowing air. And an intermediate pressure expansion valve that decompresses and expands part of the high-pressure refrigerant flowing out of the radiator until it becomes intermediate pressure refrigerant.

  Then, by causing the high-stage compression mechanism to suck the mixed refrigerant of the intermediate-pressure refrigerant decompressed by the intermediate-pressure expansion valve and the intermediate-pressure refrigerant discharged from the low-stage compression mechanism, the low-stage compression mechanism A cycle configuration of a so-called economizer refrigeration cycle in which a mixed refrigerant having a lower temperature than that in a case where only the discharged intermediate pressure refrigerant is sucked can be realized.

  In this type of economizer-type refrigeration cycle, the high-stage compression mechanism can improve the compression efficiency of the high-stage compression mechanism by sucking the low-temperature mixed refrigerant into the high-stage compression mechanism. By reducing the pressure difference between the pressure and the discharge refrigerant pressure, the compression efficiency of both compression mechanisms can be improved.

  Therefore, in the economizer refrigeration cycle, the coefficient of performance (COP) of the cycle can be improved as compared with the normal refrigeration cycle in which the pressure of the refrigerant is increased by one compression mechanism. The compression efficiency is energy conversion efficiency defined by the ratio of the work output from the compression mechanism to the work required to drive the compression mechanism.

  However, in the economizer-type refrigeration cycle, for example, when the refrigerant flow rate (hereinafter referred to as the necessary circulating refrigerant flow rate) required to circulate the cycle decreases with a decrease in air conditioning load (decrease in heating capacity) or the like. When the rotational speed of the compression mechanism is reduced, the compression efficiency of both compression mechanisms is greatly reduced, and the COP may be lower than in a normal refrigeration cycle in which the pressure of the refrigerant is increased by one compression mechanism.

  Therefore, the two-stage boosting refrigeration cycle disclosed in Patent Document 1 is configured to be switchable between a refrigerant circuit constituting the economizer refrigeration cycle and a refrigerant circuit constituting a normal refrigeration cycle for boosting the refrigerant with one compression mechanism. Depending on the outside air temperature or the temperature of the indoor blast air heated by the radiator, the refrigerant circuit is switched to the one having the higher COP.

Japanese Patent Laid-Open No. 4-80545

  However, in the two-stage boosting refrigeration cycle of Patent Document 1, since only the refrigerant circuit constituting the economizer refrigeration cycle and the refrigerant circuit constituting the normal refrigeration cycle are switched, the required circulating refrigerant flow rate is reduced. Thus, the COP cannot be sufficiently improved during the operating condition that reduces the rotational speed of the compression mechanism.

  This will be described with reference to FIG. FIG. 16 is a graph showing a change in compression efficiency with respect to the rotation speed when the compression mechanism is driven by an electric motor. Therefore, the amount of work required to drive the compression mechanism that is the denominator of the compression efficiency in FIG. 16 is the power supplied to the electric motor.

  As is apparent from FIG. 16, the compression mechanism has a maximum efficiency rotational speed at which the compression efficiency is maximum (peak), and has a characteristic that the compression efficiency is greatly reduced in a region where the rotational speed is low. Such characteristics are the same in various fixed displacement type compression mechanisms such as a rolling piston type, a reciprocating type, and a vane type.

  Also, in the two-stage boosting refrigeration cycle that boosts the refrigerant in multiple stages, the discharge flow rate (mass flow rate) of each compression mechanism at the same rotational speed is the same, so the low-stage compression mechanism and the high-stage compression mechanism are If the discharge capacity is the same, even if the refrigerant circuit constituting the economizer-type refrigeration cycle is switched to the refrigerant circuit constituting the normal refrigeration cycle, if the required circulating refrigerant flow rate does not change, the rotation speed of the compression mechanism is reduced. There is no need to change.

  That is, when the rotation speed of the compression mechanism is reduced, the rotation speed of the compression mechanism does not change even if the refrigerant circuit constituting the economizer refrigeration cycle is switched to the refrigerant circuit constituting the normal refrigeration cycle. The cycle is operated while the compression efficiency of the engine is low. Therefore, in the two-stage boosting type refrigeration cycle of Patent Document 1, the COP cannot be sufficiently improved under the operating condition in which the necessary circulating refrigerant flow rate is reduced to reduce the rotation speed of the compression mechanism.

  In view of the above points, the present invention provides a two-stage booster refrigeration cycle that can sufficiently improve the coefficient of performance (COP) of a cycle, regardless of changes in the required circulating refrigerant flow rate that requires circulation of the cycle. For the purpose.

In order to achieve the above object, according to the first aspect of the present invention, a low-stage compression mechanism (110) that compresses and discharges a low-pressure refrigerant until it becomes an intermediate-pressure refrigerant, and a low-stage compression mechanism (110) discharges the low-pressure refrigerant. A high-stage compression mechanism (120) that compresses and discharges the intermediate pressure refrigerant that has been made into a high-pressure refrigerant, a radiator (12) that radiates heat from the high-pressure refrigerant discharged from the high-stage compression mechanism (120), An intermediate pressure expansion valve (15a) that depressurizes the refrigerant flowing out of the radiator (12) until it becomes an intermediate pressure refrigerant, and a low pressure expansion valve (15b) that depressurizes the refrigerant flowing out of the radiator (12) until it becomes a low pressure refrigerant. And the evaporator (18) that evaporates the low-pressure refrigerant decompressed by the low-pressure expansion valve (15b) and flows out to the suction side of the low-stage compression mechanism (110), and the decompression by the intermediate-pressure expansion valve (15a). The intermediate pressure refrigerant that has been subjected to the high-stage compression mechanism (12 ) A two-stage booster type refrigeration cycle and an intermediate-pressure refrigerant passage (14) leading to the suction side of,
Low- pressure refrigerant connecting between the suction-side refrigerant passage connected to the suction side of the low-stage compression mechanism (110) and the intermediate-pressure refrigerant passage (14) connected to the suction side of the high-stage compression mechanism (120). A first refrigerant circuit that opens the passage (22), the intermediate pressure refrigerant passage (14) and closes the low pressure refrigerant passage (22), and a first refrigerant circuit that closes the intermediate pressure refrigerant passage (14) and opens the low pressure refrigerant passage (22). A refrigerant circuit switching means (14a, 22a ) for switching between two refrigerant circuits, and one electric motor (130) that rotationally drives both the high stage compression mechanism (120) and the low stage compression mechanism (110) ,
Further, the discharge capacity (V2) of the high-stage compression mechanism (120) is set smaller than the discharge capacity (V1) of the low-stage compression mechanism (110), and the refrigerant circuit switching means is an intermediate pressure refrigerant passage. It is characterized by comprising an intermediate pressure side opening / closing valve (14a) for opening and closing (14) and a low pressure side opening / closing valve (22a) for opening and closing the low pressure refrigerant passage (22) .

According to this, a refrigerant circuit switching means can be easily comprised by two on-off valves (14a, 22a). Then, the intermediate pressure side opening / closing valve (14a) opens the intermediate pressure refrigerant passage (14) and the low pressure side opening / closing valve (22a) closes the low pressure refrigerant passage (22). The intermediate pressure side on / off valve (14a) closes the intermediate pressure refrigerant passage (14) and the low pressure side on / off valve (22a) opens the low pressure refrigerant passage (22). The cycle can be switched to the second refrigerant circuit.
A refrigerant circuit switching means (14a, 22a) is, when the switching to the first refrigerant circuit, Ru can configure the economizer refrigeration cycle described above.
In addition, when switching to the second refrigerant circuit, it is possible to configure a refrigeration cycle that boosts the refrigerant with the high-stage compression mechanism (120) without causing the low-stage compression mechanism (110) to exhibit the refrigerant discharge capability. Therefore, it is possible to adopt a compact and simple compressor configuration in which both compression mechanisms (110, 120) are rotationally driven by one electric motor (130).

  Further, since the discharge capacity (V2) of the high-stage compression mechanism (120) is set smaller than the discharge capacity (V1) of the low-stage compression mechanism (110), the first refrigerant circuit to the second refrigerant circuit. When switching to, the rotational speed of the high-stage compression mechanism (120) can be increased so as not to change the circulating refrigerant flow rate of the cycle. Thereby, the compression efficiency of the high stage side compression mechanism (120) can be improved.

  Therefore, when the required circulating refrigerant flow rate is relatively high and the COP improvement effect by configuring the economizer refrigeration cycle can be sufficiently obtained, the first refrigerant circuit is switched to reduce the necessary circulating refrigerant flow rate, and the economizer type When the COP improvement effect by configuring the refrigeration cycle cannot be obtained, switching to the second refrigerant circuit can sufficiently obtain the COP improvement effect by improving the compression efficiency of the high stage compression mechanism (120). Can do.

  As a result, it is possible to provide a two-stage booster refrigeration cycle that can sufficiently improve the coefficient of performance (COP) of the cycle regardless of changes in the required circulating refrigerant flow rate.

In the invention according to claim 2, in the two-stage booster type refrigeration cycle according to claim 1, the refrigerant circuit control means for controlling the operation of the refrigerant circuit switching means (14a, 22a ) is provided, and the refrigerant circuit control means includes: The operation of the refrigerant circuit switching means (14a, 22a ) is controlled so as to switch to the first refrigerant circuit when the cooling capacity or heating capacity required for the cycle exceeds a predetermined first reference capacity. The operation of the refrigerant circuit switching means (14a, 22a ) is controlled so as to switch to the second refrigerant circuit when the cooling capacity or the heating capacity required for the temperature falls below a predetermined second reference capacity. .

  Here, the cooling capacity required for the refrigeration cycle is the difference between the enthalpy of the enthalpy of the refrigerant on the inlet side and the enthalpy of the refrigerant on the outlet side in the configuration in which the heat exchange target fluid is cooled in the evaporator (18). And the value obtained by integrating the flow rate of the refrigerant flowing through the evaporator (18). The heating capacity required for the refrigeration cycle is the difference between the enthalpy of the enthalpy of the refrigerant on the inlet side and the enthalpy of the outlet side refrigerant in the configuration in which the heat exchange target fluid is heated by the radiator (12). , Defined by a value obtained by integrating the flow rate of refrigerant flowing through the radiator (12).

  Therefore, as the cooling capacity or heating capacity required for the cycle increases, the necessary circulating refrigerant flow rate that requires the cycle to circulate also increases. Therefore, by switching the refrigerant circuit using the cooling capacity or the heating capacity required for the cycle as in the present claim, it is necessary to switch to the first refrigerant circuit when the required circulating refrigerant flow rate is relatively high. Switching to the second refrigerant circuit can be reliably realized when the circulating refrigerant flow rate decreases.

  Note that the cooling capacity or heating capacity required for the cycle includes the discharge refrigerant pressure discharged from the high stage compression mechanism (120), the suction refrigerant pressure sucked into the low stage compression mechanism (110), and the discharge refrigerant pressure. It can be obtained from the pressure difference from the suction refrigerant pressure, the outside air temperature and the like.

Furthermore, in the invention described in claim 3, in the two-stage booster type refrigeration cycle according to claim 2, the rotary drive control means for controlling the operation of the electric motor (130) is provided, and the rotation drive control means is included in the cycle. With the increase in the required cooling capacity or heating capacity, control is performed so as to increase the rotation speed of the electric motor (130), and the refrigerant circuit control means has a first rotation speed of the electric motor (130) determined in advance. The operation of the refrigerant circuit switching means (14a, 22a ) is controlled so as to switch to the first refrigerant circuit when the reference rotation speed is exceeded, and the rotation speed of the electric motor (130) is set to a second reference rotation that is determined in advance. The operation of the refrigerant circuit switching means (14a, 22a ) is controlled so as to switch to the second refrigerant circuit when the number becomes less than or equal to the number.

According to this, since the rotational drive control means increases the rotational speed of the electric motor (130) as the cooling capacity or heating capacity required for the cycle increases, the refrigerant circuit is switched according to the rotational speed. Thus, the refrigerant circuit can be easily switched according to the cooling capacity or heating capacity required for the cycle.

Furthermore, since the electric motor (130) rotationally drives both the low-stage compression mechanism (110) and the high-stage compression mechanism (120), the rotational speeds of both compression mechanisms (110, 120) are individually controlled. There is no need, and when the refrigerant circuit is switched, the rotation speeds of both compression mechanisms (110, 120) can be easily changed. Furthermore, since it is not necessary to provide a separate electric motor (130) for rotationally driving both compression mechanisms (110, 120), the overall size of the two-stage booster refrigeration cycle can be reduced.

According to a fourth aspect of the present invention, in the two-stage booster type refrigeration cycle according to any one of the first to third aspects, the refrigerant circuit switching means (14a, 22a ) further includes an intermediate pressure refrigerant passage (14). And a third refrigerant circuit that closes the low-pressure refrigerant passage (22) and is switchable.

According to this, the refrigerant circuit switching means (14a, 22a ) switches to the third refrigerant circuit, so that the intermediate pressure refrigerant decompressed by the intermediate pressure expansion valve (15a) is sucked into the high-stage compression mechanism (120). A refrigeration cycle that boosts the refrigerant in multiple stages in the order of the low-stage compression mechanism (110) → the high-stage compression mechanism (120) can be configured without introducing the refrigerant to the side.

  In this way, in the refrigeration cycle that boosts the refrigerant in multiple stages, the pressure difference between the suction refrigerant pressure and the discharge refrigerant pressure in both compression mechanisms (110, 120) is reduced, and the compression efficiency (110, 120) can be improved, and COP can be improved.

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim is an example which shows a corresponding relationship with the specific means as described in embodiment mentioned later.

It is a whole block diagram at the time of switching the 2 step | paragraph pressure | voltage rise type refrigerating cycle of 1st Embodiment to the 1st refrigerant circuit at the time of heating operation mode. It is a whole block diagram at the time of switching the 2nd pressure | voltage rise type refrigerating cycle of 1st Embodiment to the 3rd refrigerant circuit at the time of heating operation mode. It is a whole block diagram at the time of switching the 2nd pressure | voltage rise type refrigerating cycle of 1st Embodiment to the 2nd refrigerant circuit at the time of heating operation mode. It is a whole block diagram at the time of switching the 2 step | paragraph pressure | voltage rise type refrigerating cycle of 1st Embodiment to the refrigerant circuit at the time of air_conditionaing | cooling operation mode. It is an axial sectional view of the compressor of a 1st embodiment. (A) is AA sectional drawing of FIG. 5, (b) is BB sectional drawing of FIG. It is a graph which shows the change of COP with respect to discharge capacity ratio. It is a Mollier diagram which shows the state of the refrigerant | coolant at the time of switching the 2nd pressure | voltage rise type refrigerating cycle of 1st Embodiment to the 1st refrigerant circuit at the time of heating operation mode. It is a Mollier diagram which shows the state of the refrigerant | coolant at the time of switching the 2nd pressure | voltage rise type refrigerating cycle of 1st Embodiment to the 3rd refrigerant circuit at the time of heating operation mode. It is a Mollier diagram which shows the state of the refrigerant | coolant at the time of switching the 2 step | paragraph pressure | voltage rise type refrigerating cycle of 1st Embodiment to the 2nd refrigerant circuit at the time of heating operation mode. It is a graph which shows the relationship between the heating capability and COP which are requested | required of the two-stage pressure | voltage rise refrigerating cycle of 1st Embodiment. It is a whole block diagram at the time of switching the 2nd pressure | voltage rise type refrigerating cycle of 2nd Embodiment to the 1st refrigerant circuit at the time of heating operation mode. It is a typical block diagram of the two-stage pressure | voltage rise type compressor of 3rd Embodiment. It is a whole block diagram at the time of switching the 2nd pressure | voltage rise type refrigerating cycle of 4th Embodiment to the 1st refrigerant circuit at the time of heating operation mode. (A) is an iso-efficiency diagram according to the rotation speed Nc and the required torque Tr of the high-stage compression mechanism 120, and (b) is a graph showing a change in compression efficiency with respect to a change in the rotation speed Nc. It is a graph which shows the relationship between the rotation speed of a compression mechanism, and compression efficiency.

(First embodiment)
A first embodiment of the present invention will be described with reference to FIGS. In the present embodiment, the two-stage booster type refrigeration cycle 10 of the present invention is applied to a vehicle air conditioner 1 for an electric vehicle that obtains driving force for vehicle traveling from a traveling electric motor. The two-stage booster refrigeration cycle 10 functions to cool or heat indoor air blown into the vehicle interior, which is the air-conditioning target space, in the vehicle air conditioner 1.

  Accordingly, the two-stage booster type refrigeration cycle 10 of the present embodiment includes a heating operation mode (heating operation mode) for heating the vehicle interior and an overall configuration diagram of FIG. 4 as shown in the overall configuration diagram of FIGS. As shown, the refrigerant circuit in the cooling operation mode (cooling operation mode) for cooling the passenger compartment is configured to be switchable. 1 to 4, the refrigerant flow in the heating operation mode and the cooling operation mode is indicated by solid arrows.

  The two-stage booster refrigeration cycle 10 of the present embodiment employs a normal chlorofluorocarbon refrigerant as the refrigerant, and constitutes a vapor compression subcritical refrigeration cycle in which the high-pressure side refrigerant pressure does not exceed the critical pressure of the refrigerant. Yes. Furthermore, this refrigerant is mixed with refrigerating machine oil for lubricating the compressor 100, and this refrigerating machine oil circulates in the cycle together with the refrigerant.

  First, the compressor 100 is disposed in a bonnet, and sucks, compresses and discharges a refrigerant that is a fluid in the two-stage booster refrigeration cycle 10. In the compressor 100, two compression mechanisms, a low-stage compression mechanism 110 and a high-stage compression mechanism 120, and both compression mechanisms 110 and 120 are rotationally driven inside a casing 140 that forms an outer shell thereof. This is a two-stage booster type electric compressor configured to accommodate an electric motor 130 as a rotational driving means.

  Further, the casing 140 of the compressor 100 has a suction port 144 for sucking low-pressure refrigerant from the outside of the casing 140 into the low-stage compression mechanism 110, and an intermediate pressure for flowing intermediate-pressure refrigerant from the outside of the casing 140 into the casing 140. A port 145 and a discharge port 146 for discharging the high-pressure refrigerant discharged from the high-stage compression mechanism 120 to the outside of the casing 140 are provided. The detailed configuration of the compressor 100 will be described later.

  The refrigerant inlet side of the indoor condenser 12 is connected to the discharge port 146 of the compressor 100. The indoor condenser 12 is disposed in an air conditioning case 31 of an indoor air conditioning unit 30 of the vehicle air conditioner 1 to be described later, and the high-pressure refrigerant discharged from the compressor 100 (specifically, the high-stage compression mechanism 120). It is a radiator that heats indoor air that has been radiated and has passed through an indoor evaporator 20 described later.

  The refrigerant outlet side of the indoor condenser 12 is connected to a first three-way joint 13 a that branches the flow of the high-pressure refrigerant that has flowed out of the indoor condenser 12. The first three-way joint 13a has three inflow / outflow ports. One of the three inflow / outflow ports is a refrigerant inflow port, and two are refrigerant outflow ports. Such a three-way joint may be constituted by joining various pipes, or may be constituted by providing a plurality of refrigerant passages in a metal block or a resin block.

  A gas-liquid separator 16 is connected to one refrigerant outlet of the first three-way joint 13a via an intermediate pressure expansion valve 15a. In addition, one refrigerant inlet of the second three-way joint 13b is connected to the other refrigerant outlet via an opening / closing valve 17.

  The intermediate pressure expansion valve 15a is a variable throttle mechanism that reduces the pressure of the high-pressure refrigerant that has flowed out of the indoor condenser 12 until it becomes intermediate-pressure refrigerant. Specifically, the intermediate pressure expansion valve 15a includes a valve body configured to be able to change the throttle opening degree and an electric actuator including a stepping motor that changes the throttle opening degree of the valve body. Yes. Further, the operation of the intermediate pressure expansion valve 15a is controlled by a control signal output from an air conditioning control device described later.

  Furthermore, the intermediate pressure expansion valve 15a fully closes the throttle opening, thereby allowing the refrigerant flow in the refrigerant piping from one refrigerant outlet of the first three-way joint 13a to the inlet side of the gas-liquid separator 16 to flow. Can be blocked. Thereby, the intermediate pressure expansion valve 15 a can switch the refrigerant circuit of the two-stage booster type refrigeration cycle 10. Therefore, in the present embodiment, the intermediate pressure expansion valve 15a is used as an operation mode switching unit that switches between the refrigerant circuit in the cooling operation mode and the refrigerant circuit in the heating operation mode.

  The gas-liquid separator 16 separates the gas-liquid of the intermediate pressure refrigerant decompressed by the intermediate pressure expansion valve 15a. The gas-phase separator outlet of the gas-liquid separator 16 is connected to the intermediate-pressure port 145 of the compressor 100 via the intermediate-pressure refrigerant passage 14, and the liquid-phase refrigerant outlet is connected to the second three-way via the low-pressure expansion valve 15b. The other refrigerant inlet of the joint 13b is connected.

  The intermediate pressure refrigerant passage 14 is provided with an intermediate pressure side on-off valve 14a. The intermediate pressure side opening / closing valve 14a is an electromagnetic valve that opens and closes the intermediate pressure refrigerant passage 14, and its operation is controlled by a control signal output from the air conditioning control device. The intermediate pressure side opening / closing valve 14a is a check valve that only allows the refrigerant to flow from the gas phase refrigerant outlet of the gas-liquid separator 16 to the intermediate pressure port 145 of the compressor 100 when the intermediate pressure refrigerant passage 14 is opened. It has the function as.

  Thereby, when the intermediate pressure side opening / closing valve 14 a opens the intermediate pressure refrigerant passage 14, the refrigerant is prevented from flowing backward from the compressor 100 side to the gas-liquid separator 16. Of course, the intermediate pressure side opening / closing valve 14a may not be provided with a mechanism as a check valve, but a check valve that performs the same function may be disposed in the intermediate pressure refrigerant passage 14, or the check valve may be separated into gas and liquid. The unit 16 or the compressor 100 may be integrated.

  Furthermore, the intermediate pressure side on-off valve 14a can switch the refrigerant circuit by blocking the refrigerant flow in the intermediate pressure refrigerant passage 14. Therefore, in the present embodiment, the intermediate pressure side on-off valve 14a is used as a refrigerant circuit switching unit that switches a cycle configuration (refrigerant circuit) in the heating operation mode. The refrigerant circuit switching means has a function different from that of the operation mode switching means for switching the operation mode.

  The low-pressure expansion valve 15b removes the liquid-phase refrigerant that has been decompressed until it becomes intermediate-pressure refrigerant in the intermediate-pressure expansion valve 15a and separated by the gas-liquid separator 16 among the high-pressure refrigerant that has flowed out of the indoor condenser 12. This is a variable throttle mechanism that reduces the pressure until Further, the basic configuration is the same as that of the intermediate pressure expansion valve 15a. Therefore, the operation of the low pressure expansion valve 15b is controlled by the control signal output from the air conditioning control device.

  Further, the low-pressure expansion valve 15b shuts off the refrigerant flow in the refrigerant pipe from the liquid-phase refrigerant outlet of the gas-liquid separator 16 to the other refrigerant inlet of the second three-way joint 13b with its throttle opening fully closed. The refrigerant circuit of the two-stage booster refrigeration cycle 10 can be switched. Therefore, in the present embodiment, the low-pressure expansion valve 15b is used as an operation mode switching unit that switches between the refrigerant circuit in the cooling operation mode and the refrigerant circuit in the heating operation mode, similarly to the intermediate pressure expansion valve 15a.

  The on-off valve 17 connected to the other refrigerant outlet of the first three-way joint 13a is an electromagnetic valve whose operation is controlled by a control signal output from the air conditioning control device. Thus, the refrigerant circuit of the two-stage booster refrigeration cycle 10 can be switched. Therefore, in the present embodiment, the on-off valve 17 is used as an operation mode switching unit together with the intermediate pressure expansion valve 15a and the low pressure expansion valve 15b.

  The basic configuration of the second three-way joint 13b is the same as that of the first three-way joint 13a. In the second three-way joint 13b, two of the three inlets and outlets are used as refrigerant inlets and one is used as the refrigerant outlet with respect to the first three-way joint 13a. An outdoor heat exchanger 18 that exchanges heat between the refrigerant and the vehicle interior air (outside air) is connected to the refrigerant outlet of the second three-way joint 13b.

  The outdoor heat exchanger 18 is disposed in the hood, and functions as an evaporator that evaporates the low-pressure refrigerant decompressed by the low-pressure expansion valve 15b and exerts an endothermic action in the heating operation mode, and in the cooling operation mode. It is a heat exchanger that functions as a heat radiator that dissipates high-pressure refrigerant.

  An electric three-way valve 19 is connected to the outlet side of the outdoor heat exchanger 18. The operation of the electric three-way valve 19 is controlled by a control voltage output from the air-conditioning control device, and the operation mode switching means together with the intermediate pressure expansion valve 15a, the low pressure expansion valve 15b and the on-off valve 17 described above. Is configured.

  More specifically, in the heating operation mode, the electric three-way valve 19 switches to a refrigerant circuit that connects the outlet side of the outdoor heat exchanger 18 and one refrigerant inlet of the third three-way joint 13c, and the cooling operation mode Sometimes, the refrigerant circuit is switched to connect the outlet side of the outdoor heat exchanger 18 and the inlet side of the cooling expansion valve 15c.

  The basic configuration of the third three-way joint 13c is the same as that of the first three-way joint 13a. In the third three-way joint 13c, with respect to the first three-way joint 13a, two of the three inlets and outlets are used as refrigerant inlets, and one is used as the refrigerant outlet. The basic configuration of the cooling expansion valve 15c is the same as that of the intermediate pressure expansion valve 15a and the low pressure expansion valve 15b.

  The refrigerant inlet side of the indoor evaporator 20 is connected to the outlet side of the cooling expansion valve 15c. This indoor evaporator 20 is arranged in the air conditioning case 31 of the indoor air conditioning unit 30 on the upstream side of the indoor blast air flow of the indoor condenser 12, and evaporates the refrigerant flowing through the interior during the cooling operation mode, It is a heat exchanger for cooling which cools indoor ventilation air by exhibiting an endothermic effect.

  The other refrigerant inlet of the third three-way joint 13c is connected to the outlet side of the indoor evaporator 20, and the refrigerant inlet side of the accumulator 21 is connected to the refrigerant outlet of the third three-way joint 13c. The accumulator 21 is a low-pressure side gas-liquid separator that separates the gas-liquid refrigerant flowing into the accumulator 21 and stores excess refrigerant. Furthermore, the suction port 144 of the compressor 100 is connected to the gas-phase refrigerant outlet of the accumulator 21.

  In the present embodiment, the intermediate pressure port 145 side of the compressor 100 with respect to the intermediate pressure side opening / closing valve 14a in the intermediate pressure refrigerant passage 14 described above, and the gas phase refrigerant outlet of the accumulator 21 to the suction port 144 of the compressor 100. A low-pressure refrigerant passage 22 is provided for connecting to the refrigerant passage to reach. In other words, the low-pressure refrigerant passage 22 connects the suction side of the low-stage compression mechanism 110 and the suction side of the high-stage compression mechanism 120.

  Further, a low pressure side on / off valve 22a having the same configuration as that of the intermediate pressure side on / off valve 14a is disposed in the low pressure refrigerant passage 22. The low-pressure side opening / closing valve 22a is an electromagnetic valve that opens and closes the low-pressure refrigerant passage 22, and its operation is controlled by a control signal output from the air conditioning control device. Furthermore, the low-pressure side opening / closing valve 22a constitutes refrigerant circuit switching means for switching the cycle configuration (refrigerant circuit) in the heating operation mode, similarly to the intermediate pressure-side opening / closing valve 14a.

  Next, the indoor air conditioning unit 30 will be described. The indoor air conditioning unit 30 is arranged inside the instrument panel (instrument panel) at the foremost part of the vehicle interior to form an outer shell of the indoor air conditioning unit 30 and to the interior air blown into the vehicle interior. It has an air conditioning case 31 that forms an air passage. And the air blower 32, the indoor condenser 12 mentioned above, the indoor evaporator 20, etc. are accommodated in this air passage.

  Inside / outside air switching device 33 for switching and introducing vehicle interior air (inside air) and outside air is arranged on the most upstream side of the indoor air flow of air conditioning case 31. The inside / outside air switching device 33 continuously adjusts the opening area of the inside air introduction port for introducing the inside air into the air conditioning case 31 and the outside air introduction port for introducing the outside air by the inside / outside air switching door, so that the air volume of the inside air and the outside air are adjusted. The air volume ratio with the air volume is continuously changed.

  On the downstream side of the air flow of the inside / outside air switching device 33, a blower 32 that blows air sucked through the inside / outside air switching device 33 toward the vehicle interior is arranged. The blower 32 is an electric blower that drives a centrifugal multiblade fan (sirocco fan) with an electric motor, and the number of rotations (the amount of blown air) is controlled by a control voltage output from the air conditioning control device.

  On the downstream side of the air flow of the blower 32, the indoor evaporator 20 and the indoor condenser 12 are arranged in the order of the indoor evaporator 20 → the indoor condenser 12 with respect to the flow of the indoor blown air. In other words, the indoor evaporator 20 is arranged on the upstream side of the air flow of the indoor blown air with respect to the indoor condenser 12.

  Further, on the downstream side of the air flow of the indoor evaporator 20 and the upstream side of the air flow of the indoor condenser 12, of the cold air cooled by the indoor evaporator 20, reheating is performed by the indoor condenser 12. An air mix door 34 is arranged to adjust the ratio of the air volume to be generated. In addition, a mixing space 35 is provided on the downstream side of the air flow of the indoor condenser 12 to mix hot air that has been heated by passing through the indoor condenser 12 and cold air that has not been heated by bypassing the indoor condenser 12. It has been.

  In addition, an air outlet that blows the conditioned air mixed in the mixing space 35 into the vehicle interior that is the space to be cooled is disposed at the most downstream portion of the air flow of the air conditioning case 31. Specifically, the air outlet includes a face air outlet that blows air-conditioned air toward the upper body of the passenger in the passenger compartment, a foot air outlet that blows air-conditioned air toward the feet of the passenger, and an inner surface of the front window glass of the vehicle. A defroster outlet (both not shown) is provided to blow out the conditioned air.

  Therefore, the temperature of the conditioned air mixed in the mixing space 35 is adjusted by adjusting the ratio of the air volume that the air mix door 34 passes through the indoor condenser 12, and as a result, the air conditioner blown out from each outlet. Wind temperature is adjusted. The air mix door 34 is driven by an air mix door servo motor (not shown) whose operation is controlled by a control signal output from the air conditioning controller.

  Further, on the upstream side of the air flow of the face outlet, the foot outlet, and the defroster outlet, a face door for adjusting the opening area of the face outlet, a foot door for adjusting the opening area of the foot outlet, and the defroster outlet, respectively. A defroster door (none of which is shown) for adjusting the opening area is arranged.

  These face doors, foot doors, and defroster doors constitute the outlet mode switching means for switching the outlet mode, and the operation is controlled by a control signal output from the air conditioning controller via a link mechanism (not shown). It is driven by a servo motor for an air outlet mode door (not shown).

  Next, the detailed structure of the compressor 100 of this embodiment is demonstrated using FIG. 5 is an axial sectional view of the compressor 100, and the up and down arrows in FIG. 5 indicate the up and down directions when the compressor 100 is mounted on the vehicle. 6A is a cross-sectional view taken along the line AA in FIG. 5, and FIG. 6B is a cross-sectional view taken along the line BB in FIG.

  The compressor 100 includes a low-stage compression mechanism 110 and a high-stage compression mechanism 120, each of which is a rolling piston type compression mechanism that is a fixed capacity compression mechanism, and a rotational drive unit that rotationally drives both the compression mechanisms 110 and 120. The electric motor 130 and the like are housed in a housing space 150 formed in a casing 140 that forms the outer shell of the compressor 100.

  First, the casing 140 has a cylindrical member 141 whose axial direction extends in the horizontal direction, a low-stage lid member 142 that closes the opening of the cylindrical member 141 on the low-stage compression mechanism 110 side, and a height of the cylindrical member 141. A high-stage lid member 143 that closes the opening on the stage-side compression mechanism 120 side is provided. And these are integrally joined by joining means, such as welding, and it is set as the airtight container structure, The accommodation space 150 is formed in the inside.

  Further, a through-hole penetrating the inside and the outside is formed on the outer peripheral surface of the cylindrical member 141, and the intermediate-pressure refrigerant is introduced into the accommodation space 150 from the gas-liquid separator 16 side outside the casing 140 by the through-hole. An intermediate pressure port 145 is formed. Accordingly, the inside of the accommodation space 150 is an intermediate pressure refrigerant atmosphere. Further, an inverter 160 is attached to the outer surface of the low-stage lid member 142 in the casing 140.

  The inverter 160 outputs an alternating current having a frequency corresponding to a control signal output from the air-conditioning control device to the electric motor 130. By this frequency control, the compressor 100 (specifically, the electric motor 130) The rotation speed is controlled. That is, the refrigerant discharge capacity of the compressor 100 is controlled by this frequency control.

  Furthermore, the inverter 160 is attached so that almost the entire area of one end surface of the outer surface of the inverter 160 is in close contact with the outer surface of the low-stage side lid member 142. Thereby, heat transfer between the inverter 160 and the refrigerant in the accommodation space 150 is enabled, and the inverter 160 is cooled by the intermediate pressure refrigerant in the accommodation space 150.

  The electric motor 130 includes a stator 132 that forms a stator and a rotor 133 that forms a rotor. The stator 132 includes a stator core 132a made of a magnetic material and a stator coil 132b wound around the stator core 132a. The rotor 133 is formed in a substantially cylindrical shape extending in the rotation axis direction, and is disposed on the inner peripheral side of the stator 132.

  Further, the rotor 133 is configured to have a permanent magnet, and is a rotational drive shaft that transmits rotational driving force from the electric motor 130 to both compression mechanisms 110 and 120 through a through hole provided in the center thereof. A certain shaft 131 is fixed by press fitting. Therefore, when electric power is supplied to the stator coil 132b and a rotating magnetic field is generated, the rotor 133 and the shaft 131 rotate together.

  The shaft 131 is longer in the rotational axis direction than the rotor 133, and is rotatably supported by the low-stage bearing portion 134 at a portion closer to the low-stage compression mechanism 110 than the rotor 133. It is rotatably supported by a high-stage bearing portion 135 at a portion closer to the higher-stage compression mechanism 120 than 133.

  Furthermore, a low-stage eccentric portion 131a that is eccentric with respect to the rotation center of the shaft 131 is formed at the end of the shaft 131 on the low-stage compression mechanism 110 side. A high-stage eccentric portion 131b that is eccentric with respect to the rotation center of the shaft 131 is formed at the end of the shaft.

  These low stage side eccentric part 131a and high stage side eccentric part 131b constitute a connecting part to low stage side compression mechanism 110 and low stage side compression mechanism 120, respectively. Therefore, in the compressor 100 of the present embodiment, both the compression mechanisms 110 and 120 are arranged on both ends of the shaft 131 so as to sandwich the electric motor 130 from both sides in the horizontal direction.

  The low-stage compression mechanism 110 compresses and discharges the low-pressure refrigerant until it becomes an intermediate-pressure refrigerant. The low-stage compression mechanism 110 is an approximately cylindrical low-stage cylinder 111 whose axial direction extends in the horizontal direction. A cylindrical low-stage rotor 112 disposed on the circumferential side, a low-stage side cylinder 111, and a low-stage side rotor 112, and a low-stage side vane 113 that divides the low-stage refrigerant compression space 117 are formed. ing.

  A low stage side bearing plate 114 having a low stage side bearing part 134 fixed to the center thereof is disposed on the electric motor 130 side of the low stage side cylinder 111, and the electric motor of the low stage side cylinder 111 is arranged. On the opposite side of 130, a low-stage discharge plate 115 in which a low-stage refrigerant discharge port 115a is formed is disposed. Thereby, a space for accommodating the low-stage rotor 112 is formed on the inner peripheral side of the low-stage cylinder 111.

  Further, an insertion hole into which the low-stage eccentric portion 131a of the shaft 131 is inserted is provided at the center of the low-stage rotor 112. And the shaft 131 and the low stage side rotor 112 are connected by inserting the low stage side eccentric part 131a rotatably in this insertion hole. As a result, the lower stage rotor 112 rotates eccentrically in the columnar space with the outer peripheral surface of the cylinder contacting the inner peripheral surface of the lower stage cylinder 111 as the shaft 131 rotates.

  Further, as shown in FIG. 6A, a recessed hole that is recessed in the radial direction is formed on the inner peripheral side of the low-stage side cylinder 111, and in this recessed hole, the low-stage side spring 116 and the low-stage side spring A stage side vane 113 is accommodated. The depression hole communicates with the accommodation space 150, and an intermediate pressure is applied to the back surface of the vane 113. Therefore, the tip of the low-stage vane 113 is always in contact with the outer peripheral surface of the low-stage rotor 112 due to the load and back pressure of the low-stage spring 116.

  Therefore, it is surrounded by the contact portion between the low-stage cylinder 111 and the low-stage rotor 112, the contact portion between the low-stage vane 113 and the low-stage rotor 112, the low-stage bearing plate 114, and the low-stage discharge plate 115. Due to this space, a low-stage refrigerant compression space 117 for compressing the low-pressure refrigerant is formed.

  Further, a low-stage side refrigerant suction port 111 a through which low-pressure refrigerant is sucked into the low-stage side compression space 117 is formed on the cylindrical wall surface of the low-stage side cylinder 111. As shown in FIG. 6A, the above-described suction port 144 is connected to the low-stage side refrigerant suction port 111a via a suction pipe 118 constituting a suction passage.

  Further, the low-stage side refrigerant discharge port 115 a formed in the low-stage side discharge plate 115 opens into the accommodation space 150 in the casing 140. Further, a low-stage reed valve 115b that allows only a refrigerant to flow from the low-stage refrigerant discharge outlet 115a to the accommodating space 150 in the casing 140 is disposed at the low-stage refrigerant discharge opening 115a.

  Therefore, in the low-stage compression mechanism 110, as the shaft 131 rotates, the low-stage refrigerant compression space 117 decreases in volume from the low-stage refrigerant suction port 111a side to the low-stage refrigerant discharge port 115a side. When the refrigerant is compressed by moving and exceeds the valve opening pressure of the low-stage side reed valve 115b, the refrigerant is discharged from the low-stage side refrigerant discharge port 115a into the accommodating space 150 in the casing 140.

  The high-stage compression mechanism 120 compresses and discharges the intermediate pressure refrigerant in the accommodation space 150 until it becomes a high-pressure refrigerant, and the basic configuration thereof is the same as that of the low-stage compression mechanism 110. Accordingly, the high-stage compression mechanism 120 also has the same configuration as the low-stage compression mechanism 110, the high-stage cylinder 121, the high-stage rotor 122, the high-stage vane 123, the high-stage bearing plate 124, the high-stage discharge. A plate 125, a high-stage spring 126, and the like are included.

  Further, as shown in FIG. 6 (b), a high stage side refrigerant suction port 121 a for sucking intermediate pressure refrigerant into the high stage side refrigerant compression space 127 is opened on the cylindrical side surface of the high stage side cylinder 121. ing. The high-stage side refrigerant discharge port 125a formed in the high-stage side discharge plate 125 functions as a high-stage check valve that only allows refrigerant to flow from the high-stage side refrigerant discharge port 125a to the discharge passage side. A stage side reed valve 125b is arranged.

  The high-stage refrigerant discharge port 125a is disposed in the casing 140 through the discharge passage 128 and the oil separation space 170 formed in the partition plate 171 that partitions the housing space 150 and an oil separation space 170 described later. The discharge port 146 is connected.

  Therefore, in the high stage side compression mechanism 120, the volume of the high stage side refrigerant compression space 127 is reduced from the high stage side refrigerant suction port 121a side to the high stage side refrigerant discharge port 125a side as the shaft 131 rotates. When the refrigerant is compressed by moving and exceeds the valve opening pressure of the high-stage reed valve 125b, the refrigerant is discharged from the high-stage refrigerant discharge port 125a to the outside of the compressor 100 via the oil separation space 170 and the discharge port 146. The refrigerant is discharged.

  The oil separation space 170 is a separation space that is formed between the discharge passage 128 and the discharge port 146 and separates the refrigerating machine oil from the refrigerant discharged from the high-stage compression mechanism 120. More specifically, the high-pressure refrigerant discharged from the discharge passage 128 collides with the high-stage side cover member 143 to reduce the flow rate of the high-pressure refrigerant, and further, refrigeration oil having a higher specific gravity than the gas-phase refrigerant due to the action of gravity. Is a space that constitutes a so-called collision-type oil separator, in which the oil is dropped and stored downward.

  Accordingly, the discharge port 146 is formed above the oil surface of the refrigerating machine oil that accumulates in the oil separation space 170. Further, the oil separation space 170 is provided with an oil introduction pipe 172 for guiding the refrigeration oil stored in the oil separation space 170 to the sliding portions of the low-stage compression mechanism 110 and the high-stage compression mechanism 120. .

  Furthermore, in this embodiment, as shown in FIG. 5, the inner diameter dimension of the high-stage cylinder 121 and the inner diameter dimension of the low-stage cylinder 111 are substantially equal, and the shafts of the high-stage cylinder 121 and the high-stage rotor 122 are arranged. The direction dimension is shorter than the axial dimension of the low-stage cylinder 111 and the low-stage rotor 112. That is, the discharge capacity V2 of the high-stage compression mechanism 120 of the present embodiment is set to be smaller than the discharge capacity V1 of the low-stage compression mechanism 110.

  Here, the two-stage booster type refrigeration cycle 10 sucks the low-pressure refrigerant into the low-stage compression mechanism 110, causes the intermediate-pressure refrigerant to flow into the accommodation space 150 from the intermediate pressure port 145, and the low-stage refrigerant into the high-stage compression mechanism 120. When configuring a cycle (the aforementioned economizer refrigeration cycle) that sucks the mixed refrigerant of the intermediate pressure refrigerant discharged from the stage side compression mechanism 110 and the intermediate pressure refrigerant flowing in from the intermediate pressure port 145, the low pressure refrigerant It is known that the coefficient of performance (COP) of the cycle changes depending on the pressure ratio of the intermediate pressure refrigerant and the high pressure refrigerant.

  More specifically, in this type of economizer-type refrigeration cycle, the COP approaches a maximum value by adjusting the pressure of the intermediate pressure refrigerant to be about the square root of the product of the pressure of the high pressure refrigerant and the low pressure refrigerant. It has been known.

  On the other hand, in the present embodiment, since the low-stage compression mechanism 110 and the high-stage compression mechanism 120 are rotationally driven by the common electric motor 130, the low-stage compression mechanism 110 and the high-stage compression mechanism 120 are high. The rotation speed of the stage side compression mechanism 120 is the same. Therefore, by changing the discharge capacity V1 of the low-stage compression mechanism 110 and the discharge capacity V2 of the high-stage compression mechanism 120, the pressure ratio of the above-described low-pressure refrigerant, intermediate-pressure refrigerant, and high-pressure refrigerant can be easily changed. it can.

  Further, according to the study by the present inventors, as shown in FIG. 7, the discharge volume ratio V2 / V1 of the discharge capacity V2 of the high stage compression mechanism 120 to the discharge capacity V1 of the low stage compression mechanism 110 is 0. When it is about 6 to 0.7, the heating capacity of the indoor blown air required for the two-stage booster type refrigeration cycle 10 becomes a normal capacity assumed in advance, or during normal operation or than during normal operation The COP approaches the maximum value even at the time of high load operation that increases.

  Therefore, in the present embodiment, the discharge capacity V1 of the low-stage compression mechanism 110 and the discharge capacity V2 of the high-stage compression mechanism 120 are set so that 0.4 ≦ V2 / V1 ≦ 0.9. More preferably, the discharge capacity V1 of the low-stage compression mechanism 110 and the discharge capacity V2 of the high-stage compression mechanism 120 may be set so that 0.5 ≦ V2 / V1 ≦ 0.8.

  FIG. 7 is a graph showing changes in COP with respect to changes in the discharge capacity ratio V2 / V1. Further, the discharge capacity of the compression mechanism is a theoretical flow rate (push-off volume) discharged by the compression mechanism per rotation, and can be represented by a geometrically calculated flow rate.

  Next, the electric control unit of this embodiment will be described. An air conditioning control device (not shown) is composed of a well-known microcomputer including a CPU, ROM, RAM, and its peripheral circuits, and performs various calculations and processing based on an air conditioning control program stored in the ROM. It controls the operation of various connected air-conditioning control devices (compressor 100, operation mode switching means 15a, 15b, 17, 19, refrigerant circuit switching means 14a, 22a, blower 32, etc.).

  Further, on the input side of the air conditioning control device, an inside air sensor that detects the temperature inside the vehicle, an outside air sensor that detects outside air temperature, a solar radiation sensor that detects the amount of solar radiation in the vehicle interior, and the temperature of air blown out from the indoor evaporator 20 (evaporation) Various air conditioning controls such as an evaporator temperature sensor for detecting the compressor temperature), a discharge pressure sensor for detecting the high-pressure refrigerant pressure discharged from the compressor 100, and a suction pressure sensor for detecting the suction refrigerant pressure sucked into the compressor 100. Sensor groups for the above are connected.

  Further, an operation panel (not shown) disposed near the instrument panel in front of the passenger compartment is connected to the input side of the air conditioning control device, and operation signals from various air conditioning operation switches provided on the operation panel are input. . Specifically, various air conditioning operation switches provided on the operation panel include an operation switch of the vehicle air conditioner 1, a vehicle interior temperature setting switch for setting the vehicle interior temperature, a selection switch between the cooling operation mode and the heating operation mode, and the like. Is provided.

  Note that the air conditioning control device is configured integrally with control means for controlling the operation of various air conditioning control devices connected to the output side of the air conditioning control device. In this embodiment, the air conditioning control device Among them, the configuration (hardware and software) for controlling the operation of the electric motor 130 (specifically, the inverter 160) of the compressor 100 constitutes the rotational drive control means.

  Further, the configuration for controlling the operation of the operation mode switching means (specifically, the intermediate pressure expansion valve 15a, the low pressure expansion valve 15b, the on-off valve 17 and the electric three-way valve 19) constitutes the operation mode control means, and the refrigerant circuit The configuration for controlling the operation of the switching means (specifically, the intermediate pressure side on / off valve 14a and the low pressure side on / off valve 22a) constitutes the refrigerant circuit control means. Of course, the rotation drive control means, the operation mode control means, and the refrigerant circuit control means may be configured as separate control devices for the air conditioning control device.

  Next, the operation of the vehicle air conditioner 1 of the present embodiment having the above configuration will be described. In the vehicle air conditioner of this embodiment, as described above, it is possible to switch between the heating operation mode for heating the vehicle interior and the cooling operation mode for cooling the vehicle interior.

  First, the heating operation mode will be described. The heating operation mode is started when the heating operation mode is selected by the selection switch while the operation switch of the vehicle air conditioner is turned on (ON). When the heating operation mode is started, the operation mode control means switches the operation states of the intermediate pressure expansion valve 15a, the low pressure expansion valve 15b, the on-off valve 17 and the electric three-way valve 19 constituting the operation mode switching means.

  Specifically, the intermediate pressure expansion valve 15a and the low pressure expansion valve 15b are in the throttled state, the throttle passage area opening is set to a predetermined opening, the on-off valve 17 is closed, and the electric three-way valve 19 is connected to the outdoor heat exchanger. The outlet side of 18 and the one refrigerant inlet of the third three-way joint 13c are switched so as to be connected. Thereby, in the two-stage pressure | voltage rise refrigerating cycle 10 at the time of heating operation mode, it switches to the cycle which makes the indoor condenser 12 function as a heat radiator, and functions the outdoor heat exchanger 18 as an evaporator.

  Further, in the heating operation mode of the present embodiment, the intermediate pressure side on-off valve 14a constituting the refrigerant circuit switching means by the refrigerant circuit control means according to the heating capacity of the indoor blown air required for the two-stage booster refrigeration cycle 10 and The operating state of the low-pressure side opening / closing valve 22a is switched. Thereby, the two-stage pressure | voltage rise refrigerating cycle 10 of this embodiment is switched to three types of refrigerant circuits of the 1st-3rd refrigerant circuit demonstrated below.

(A) First refrigerant circuit in heating operation mode The first refrigerant circuit is used in normal operation in which the heating capacity required for the two-stage booster refrigeration cycle 10 in the heating operation mode is a normal capacity assumed in advance, or This is a cycle that can be switched during high-load operation that is higher than during normal operation. Furthermore, the first refrigerant circuit also has a cycle configuration in an initial state when the operation in the heating operation mode is started. In addition, the output at the time of normal operation of the two-stage pressure | voltage rise type refrigerating cycle 10 of this embodiment is about 2.0-2.5 kW.

  Specifically, when the operation in the heating operation mode is started, or when the heating operation mode is switched from the second and third refrigerant circuits to the first refrigerant circuit, the refrigerant circuit control means has the intermediate pressure side on-off valve. While opening 14a, the low-pressure side on-off valve 22a is closed. As a result, as shown in FIG. 1, the intermediate-pressure gas-phase refrigerant flowing out from the gas-liquid separator 16 can flow through the intermediate-pressure refrigerant passage 14 and the low-pressure refrigerant passage 22 is blocked.

  With this refrigerant circuit configuration (cycle configuration), the air conditioning control device reads the detection signal of the above-described sensor group for air conditioning control and the operation signal of the operation panel. And the target blowing temperature TAO which is the target temperature of the air which blows off into a vehicle interior is calculated based on the value of a detection signal and an operation signal. Furthermore, based on the calculated target blowing temperature TAO and the detection signal of the sensor group, the operating states of various air conditioning control devices connected to the output side of the air conditioning control device are determined.

  For example, with respect to the target air flow rate of the blower 32, that is, the control voltage output to the electric motor of the blower 32, the target blowout temperature TAO is determined based on the target blowout temperature TAO with reference to a control map stored in advance in the air conditioning control device. It is determined to be higher at the high temperature and at the low temperature than at the intermediate temperature.

  Further, the refrigerant discharge capacity of the compressor 100, that is, the control signal output to the inverter 160 connected to the electric motor 130 of the compressor 100, is accompanied by an increase in the heating capacity required for the two-stage booster refrigeration cycle 10. Then, control is performed so as to increase the rotation speed of the electric motor 130.

  More specifically, a control map stored in advance in the air conditioning control device based on the target blowing temperature TAO, the high-pressure refrigerant pressure discharged from the compressor 100, the suction refrigerant pressure sucked into the compressor 100, and the outside air temperature is stored. With reference to the control signal output to the inverter 160 so as to increase the rotation speed of the electric motor 130 with the increase of the target blowing temperature TAO, the increase of the discharge refrigerant pressure, the decrease of the intake refrigerant pressure, and the decrease of the outside air temperature. decide.

  For the control signal output to the servo motor of the air mix door 34, the target blow temperature TAO, the detected value of the blown air temperature from the indoor evaporator 20, and the detected value of the refrigerant temperature discharged from the compressor 100 are used. Thus, the temperature of the air blown into the passenger compartment is determined so as to be a desired temperature for the passenger set by the passenger compartment temperature setting switch. In the heating operation mode, the opening degree of the air mix door 34 may be controlled so that the total amount of indoor air blown from the blower 32 passes through the indoor condenser 12.

  Then, the control voltage and control signal determined as described above are output to various air conditioning control devices. After that, until the operation of the vehicle air conditioner is requested by the operation panel, the above detection signal and operation signal are read at every predetermined control cycle → the target blowout temperature TAO is calculated → the operating states of various air conditioning control devices are determined → Repeat control routines such as control voltage and control signal output.

Accordingly, the two-stage booster type refrigeration cycle 10, as shown in the Mollier diagram of FIG. 8, the inflow high pressure refrigerant discharged from the discharge port 146 of the compressor 100 (a2 ₈ points in Fig. 8) into the indoor condenser 12 dissipating and (a _8-point in FIG. 8 → b ₈ points). Thereby, the indoor air blown from the blower 32 and passed through the indoor evaporator 20 is heated.

The refrigerant flowing from the indoor condenser 12, the on-off valve 17 is closed, flows into the intermediate pressure expansion valve 15a, is decompressed and expanded until the intermediate-pressure refrigerant (b ₈ points in Fig. 8 → c ₈ point). The intermediate-pressure refrigerant decompressed and expanded by the intermediate pressure expansion valve 15a is gas-liquid separated by the gas-liquid separator 16 (c ₈ points in Fig. 8 → d ₈ points and c ₈ points → e ₈ points).

Then, the gas-phase refrigerant separated by the gas-liquid separator 16 flows into the compressor 100 from the intermediate pressure port 145 of the compressor 100, and the refrigerant discharged from the low-stage compression mechanism 110 ( 8 (point a0 _{8 in} FIG. 8) (point a1 _{8 in} FIG. 8) and sucked into the high-stage compression mechanism 120. On the other hand, the liquid-phase refrigerant separated by the gas-liquid separator 16 flows into the low-pressure expansion valve 15b, is decompressed and expanded until the low-pressure refrigerant (e ₈ points in Fig. 8 → f ₈ points).

The low-pressure refrigerant decompressed and expanded by the low-pressure expansion valve 15b flows into the outdoor heat exchanger 18 through the second three-way joint 13b. The low-pressure refrigerant that has flowed into the outdoor heat exchanger 18 absorbs heat from the outside air and evaporates (point f ₈ → point h _{8 in} FIG. 8).

The refrigerant flowing out of the outdoor heat exchanger 18 is switched to the refrigerant flow path in which the electric three-way valve 19 connects the outlet side of the outdoor heat exchanger 18 and one refrigerant inlet of the third three-way joint 13c. Then, it flows into the accumulator 21 through the third three-way joint 13c. Then, the refrigerant flowing out from the accumulator 21 (point h _{8 in} FIG. 8) is sucked from the suction port 144 of the compressor 100 and compressed again.

  The refrigerant that has flowed into the accumulator 21 is gas-liquid separated when the heating capacity required for the cycle fluctuates, and the state of the refrigerant that flows into the accumulator 21 and the refrigerant that flows out of the accumulator 21 when the cycle operation is stabilized. The state of is substantially the same. That is, FIG. 8 illustrates a state in which the cycle operation is stable.

  As described above, when switching to the first refrigerant circuit, the amount of heat of the refrigerant discharged from the high-stage compression mechanism 120 of the compressor 100 in the indoor condenser 12 is radiated to the indoor blown air and heated. The indoor air can be blown into the passenger compartment. Thereby, heating of a vehicle interior is realizable.

  Further, in the first refrigerant circuit, the low-pressure refrigerant decompressed by the low-pressure expansion valve 15b is sucked into the low-stage compression mechanism 110, and the intermediate-pressure refrigerant decompressed by the intermediate-pressure expansion valve 15a and the low-stage compression mechanism 110 are used. The above-described economizer refrigeration cycle in which the mixed refrigerant with the intermediate pressure refrigerant discharged from the refrigerant is sucked into the high-stage compression mechanism 120 can be configured.

  Therefore, by allowing the high-stage compression mechanism 120 to suck in the low-temperature mixed refrigerant, the compression efficiency of the high-stage compression mechanism 120 can be improved, and the suction refrigerant pressure in both the compression mechanisms 110 and 120 can be increased. By reducing the pressure difference from the discharge refrigerant pressure, the compression efficiency of both the compression mechanisms 110 and 120 can be improved. As a result, the COP of the two-stage booster refrigeration cycle 10 can be improved.

(B) Third Refrigerant Circuit in Heating Operation Mode Here, the heating capacity of the indoor blown air required for the two-stage booster refrigeration cycle 10 is the enthalpy of the indoor condenser 12 inlet side refrigerant and the outlet side refrigerant enthalpy. The enthalpy difference is represented by a value obtained by integrating the flow rate of the refrigerant flowing through the indoor condenser 12.

  Therefore, at the time of low load operation in which the heating capacity required for the two-stage booster refrigeration cycle 10 is lower than that during normal operation, the necessary circulating refrigerant flow rate that is required to circulate the cycle may be reduced. That is, when the two-stage booster refrigeration cycle 10 is in a low load operation, the rotation speed of the compression mechanism may be reduced according to the required circulating refrigerant flow rate.

  However, as described above, when the rotational speed of the compression mechanism is decreased, the compression efficiency of both the compression mechanisms 110 and 120 also decreases. As a result, even if the two-stage booster refrigeration cycle 10 is switched to the first refrigerant circuit and the economizer refrigeration cycle is configured, if the required heating capacity of the indoor blown air decreases, the two-stage booster refrigeration cycle 10 There is concern that COP cannot be improved.

  Therefore, in the two-stage boosting refrigeration cycle 10 of the present embodiment, the heating capacity required for the two-stage boosting refrigeration cycle 10 is equal to or lower than the third reference capacity in the state where the first refrigerant circuit is in the heating operation mode. When it becomes, it is made to switch to a 3rd refrigerant circuit as what was at the time of low load operation. The term “third” is used prior to the term “second” in order to match the term described in the claims. Moreover, the output at the time of low load operation | movement of the two step | paragraph pressure | voltage rise type refrigerating cycle 10 of this embodiment is about 1.5-2.0 kW.

  Further, the heating capacity required for the two-stage booster refrigeration cycle 10 can be obtained from the high-pressure refrigerant pressure discharged from the compressor 100, the suction refrigerant pressure sucked into the compressor 100, the outside air temperature, and the like. Further, as described above, in the present embodiment, the rotational speed of the electric motor 130 of the compressor 100 is determined based on these parameters.

  Therefore, in the present embodiment, when the rotation speeds of both the compression mechanisms 110 and 120 are equal to or lower than a predetermined third reference rotation speed, the heating capacity required for the two-stage booster refrigeration cycle 10 is the third reference. Switching to the third refrigerant circuit is performed assuming that the capacity is below the capacity. The third reference rotational speed is set to a value lower than the rotational speed assumed during normal operation.

  Specifically, when the two-stage booster type refrigeration cycle 10 is switched to the third refrigerant circuit, the refrigerant circuit control means closes the intermediate pressure side opening / closing valve 14a and closes the low pressure side opening / closing valve 22a. Thereby, as shown in FIG. 2, both the intermediate pressure refrigerant passage 14 and the low pressure refrigerant passage 22 are blocked.

  In this refrigerant circuit configuration (cycle configuration), the air conditioning control device reads the detection signal of the sensor group for air conditioning control and the operation signal of the operation panel in the same manner as when the air conditioning control device is switched to the first refrigerant circuit, and the target blowing temperature Based on the detection signals of the TAO and the sensor group, the operating states of various air conditioning control devices connected to the output side of the air conditioning control device are determined.

  Further, when switching to the third refrigerant circuit, the control signal output to the inverter 160 connected to the electric motor 130 of the compressor 100 is determined when switching to the first refrigerant circuit. It is determined so that the number of rotations of the electric motor 130 increases from the control signal.

  Here, the increase amount of the rotation speed in the third refrigerant circuit will be described. When the two-stage booster refrigeration cycle 10 is switched to the third refrigerant circuit, the intermediate-pressure refrigerant passage 14 is blocked, so the high-stage compression mechanism 120 sucks the intermediate-pressure refrigerant discharged by the low-stage compression mechanism 110. Will do. Further, the intermediate pressure refrigerant discharged by the low-stage compression mechanism 110 has a lower density than the mixed refrigerant sucked by the high-stage compression mechanism 120 when the first refrigerant circuit is switched.

  Therefore, when the number of revolutions of the electric motor 130 of the compressor 100 is not increased when switching from the first refrigerant circuit to the third refrigerant circuit, the compressor 100 cannot discharge the necessary circulating refrigerant flow rate.

  Therefore, in the present embodiment, when the first refrigerant circuit is switched to the third refrigerant circuit, the rotation speed is increased so that the compressor 100 can discharge the necessary circulating refrigerant flow rate. The determination of the operating state of other various air conditioning control devices and other control modes are the same as when switching to the first refrigerant circuit.

Therefore, in the two-stage booster refrigeration cycle 10 when switched to the third refrigerant circuit, as shown in the Mollier diagram of FIG. 9, the high-pressure refrigerant discharged from the discharge port 146 of the compressor 100 (a2 in FIG. 9). ₉ points) flows into the indoor condenser 12 and dissipates heat (a2 ₉ points → b ₉ points in FIG. 9). Thereby, the indoor air blown from the blower 32 and passed through the indoor evaporator 20 is heated.

  Further, the refrigerant flowing out of the indoor condenser 12 is decompressed and expanded by the intermediate pressure expansion valve 15a until it becomes an intermediate pressure refrigerant, and flows into the gas-liquid separator 16 in the same manner as when switching to the first refrigerant circuit. To do. When the operation of the cycle is stabilized while switching to the third refrigerant circuit, the state of the refrigerant flowing into the gas-liquid separator 16 and the state of the refrigerant flowing out from the gas-liquid separator 16 become substantially the same. That is, FIG. 9 illustrates a state in which the cycle operation is stable.

The refrigerant flowing into the gas-liquid separator 16 does not flow out to the intermediate pressure port 145 side of the compressor 100 because the intermediate pressure side opening / closing valve 14a is closed, and flows into the low pressure expansion valve 15b to become low pressure refrigerant. until decompressing and expanding (c ₉ points in FIG. 9 → f ₉ points). The refrigerant decompressed by the low-pressure expansion valve 15b, similar to the case which has been switched to the first refrigerant circuit, flows into the outdoor heat exchanger 18, and absorbs heat from outside air to evaporate (f ₉ of 9 points → h ₉ points).

Further, the refrigerant flowing out of the outdoor heat exchanger 18 is sucked from the suction port 144 of the compressor 100 via the accumulator 21. The refrigerant sucked from the suction port 144 of the compressor 100 is boosted by the low-stage compression mechanism 110 and is sucked into the high-stage compression mechanism 120 without joining the refrigerant flowing from the intermediate pressure port 145 ( h ₉ points → a0 ₉ points in FIG. 9).

  As described above, when switching to the third refrigerant circuit, the amount of heat of the refrigerant discharged from the high-stage compression mechanism 120 of the compressor 100 in the indoor condenser 12 is radiated to the indoor blown air and heated. The indoor air can be blown into the passenger compartment. Thereby, heating of a vehicle interior is realizable.

  Further, in the third refrigerant circuit, when the rotation speed of both compression mechanisms 110 and 120 is reduced as the required heating capacity of the indoor blown air is reduced, both compressions are performed with respect to the first refrigerant circuit. Decreasing the compression efficiency can be suppressed by increasing the number of rotations of the mechanisms 110 and 120. Further, the compression efficiency of both the compression mechanisms 110 and 120 can be improved by reducing the pressure difference between the suction refrigerant pressure and the discharge refrigerant pressure in both the compression mechanisms 110 and 120. As a result, the COP of the two-stage booster refrigeration cycle 10 can be improved.

  Further, when the rotation speed of both the compression mechanisms 110 and 120 becomes equal to or higher than a predetermined first reference rotation speed while being switched to the third refrigerant circuit, the two-stage booster refrigeration cycle 10 is requested. The control described in (a) is performed by switching to the first refrigerant circuit on the assumption that the heating capacity to be performed is equal to or higher than the first reference capacity corresponding to the lower limit value of the normal capacity assumed during normal operation. . The first reference rotational speed is set to a value higher than the third reference rotational speed.

(C) Second refrigerant circuit in heating operation mode The second refrigerant circuit is in a state where it is a third refrigerant circuit in the heating operation mode, and further, the required heating capacity of the indoor blown air is reduced and the load is extremely low. When it becomes necessary to further reduce the rotational speed of the compression mechanism during operation, the compression efficiency of both compression mechanisms 110 and 120 is reduced, and the COP of the two-stage booster refrigeration cycle 10 cannot be improved. This is a refrigerant circuit that is switched in order to suppress the occurrence of this.

  In the present embodiment, when the heating capacity required for the two-stage booster type refrigeration cycle 10 is equal to or lower than the second reference capacity in the state where the third refrigerant circuit is in the heating operation mode, the operation becomes an extremely low load operation. For example, the second refrigerant circuit is switched. In addition, the output at the time of the ultra-low load operation | movement of the two step | paragraph pressure | voltage rise type refrigerating cycle 10 of this embodiment is about 1.0-1.5 kW.

  More specifically, as in the case of switching from the first refrigerant circuit to the third refrigerant circuit, when the rotation speeds of both the compression mechanisms 110 and 120 are equal to or lower than a predetermined second reference rotation speed, a two-stage The heating capacity required for the booster refrigeration cycle 10 is switched to the second refrigerant circuit on the assumption that the heating capacity is less than or equal to the second reference capacity. The second reference rotation speed is set to a value lower than the rotation speed assumed during normal operation and further lower than the third reference rotation speed.

  When switching the two-stage booster refrigeration cycle 10 to the second refrigerant circuit, the refrigerant circuit control means closes the intermediate pressure side on / off valve 14a and opens the low pressure side on / off valve 22a. As a result, as shown in FIG. 3, a cycle is formed in which the suction side and the discharge side of the low-stage compression mechanism 110 communicate with each other via the low-pressure refrigerant passage 22, and the low-stage compression mechanism 110 has a refrigerant discharge capacity. A cycle in which the pressure of the refrigerant is boosted by the high-stage compression mechanism 120 without being exhibited is configured.

  In this refrigerant circuit configuration (cycle configuration), the air conditioning control device reads the detection signal of the sensor group for air conditioning control and the operation signal of the operation panel in the same manner as when switching to the first and third refrigerant circuits, Based on the target blowing temperature TAO and the detection signal of the sensor group, the operating states of various air conditioning control devices connected to the output side of the air conditioning control device are determined.

  Furthermore, when switching to the second refrigerant circuit, the low-stage compression mechanism 110 does not exhibit the refrigerant discharge capability, and the high-stage compression mechanism 120 having a smaller discharge capacity than the low-stage compression mechanism 110 is used. Therefore, the control signal output to the inverter 160 connected to the electric motor 130 of the compressor 100 is higher than the control signal determined when switching to the third refrigerant circuit. The number of rotations is determined to increase.

  Specifically, the rotation speed of the electric motor 130 is the same as the rotation speed at the time of switching from the third refrigerant circuit to the second refrigerant circuit or immediately before switching, and the high-stage compression mechanism 120 with respect to the discharge capacity V1 of the low-stage compression mechanism 110. It can be determined as a value divided by the discharge capacity ratio V2 / V1 of the discharge capacity V2. The determination of the operating state of other various air conditioning control devices and other control modes are the same as when switching to the first and third refrigerant circuits.

Therefore, in the two-stage booster refrigeration cycle 10 when switched to the second refrigerant circuit, as shown in the Mollier diagram of FIG. 10, the high-pressure refrigerant discharged from the discharge port 146 of the compressor 100 (a2 in FIG. 10). ₁₀ points) flows into the indoor condenser 12 and dissipates heat (a2 ₁₀ points → b ₁₀ points in FIG. 10). Thereby, the indoor air blown from the blower 32 and passed through the indoor evaporator 20 is heated.

  Further, the refrigerant flowing out from the indoor condenser 12 is decompressed and expanded by the intermediate pressure expansion valve 15a until it becomes an intermediate pressure refrigerant, similarly to the case where the refrigerant is switched to the first and third refrigerant circuits, and the gas-liquid separator 16 flows in. When the operation of the cycle is stabilized while switching to the second refrigerant circuit, the state of the refrigerant flowing into the gas-liquid separator 16 and the state of the refrigerant flowing out from the gas-liquid separator 16 become substantially the same. That is, FIG. 10 illustrates a state in which the cycle operation is stable.

The refrigerant flowing into the gas-liquid separator 16 does not flow out to the intermediate pressure port 145 side of the compressor 100 because the intermediate pressure side opening / closing valve 14a is closed, and flows into the low pressure expansion valve 15b to become low pressure refrigerant. until decompressing and expanding (c ₁₀ points in FIG. 10 → f ₁₀ points). The refrigerant decompressed by the low-pressure expansion valve 15b, similar to the case which has been switched to the first refrigerant circuit, flows into the outdoor heat exchanger 18, and absorbs heat from outside air to evaporate (f ₁₀ in FIG. 10 → a0 ₁₀ points).

  The refrigerant that has flowed out of the outdoor heat exchanger 18 is sucked from the suction port 144 and the intermediate pressure port 145 of the compressor 100 through the accumulator 21 because the low-pressure side opening / closing valve 22a is open.

  At this time, the suction side and the discharge side of the low-stage compression mechanism 110 communicate with each other through the low-pressure refrigerant passage 22, so that the low-stage compression mechanism 110 is in a so-called idle state and does not exhibit the refrigerant discharge capability. Therefore, the gas-phase refrigerant separated by the accumulator 21 is substantially sucked from the intermediate pressure port 145 to the high-stage compression mechanism 120 and compressed again.

  As described above, when switching to the second refrigerant circuit, the indoor condenser 12 releases heat from the refrigerant discharged from the high-stage compression mechanism 120 of the compressor 100 to the indoor blown air and is heated. The indoor air can be blown into the passenger compartment. Thereby, heating of a vehicle interior is realizable.

  Furthermore, in the second refrigerant circuit, when it is necessary to reduce the rotational speeds of both the compression mechanisms 110 and 120 as the required heating capacity of the indoor blown air decreases, the low-stage compression mechanism 110 Switching to the single-stage compression cycle configuration in which the refrigerant is boosted by the high-stage compression mechanism 120 without exhibiting the refrigerant discharge capability can increase the rotation speed of the high-stage compression mechanism 120.

  More specifically, since the discharge capacity V2 of the high-stage compression mechanism 120 is set to be smaller than the discharge capacity V1 of the low-stage compression mechanism 110, when switching from the third refrigerant circuit to the second refrigerant circuit, In order to cause the compressor 100 to discharge the necessary circulating refrigerant flow rate, the rotational speed of the high-stage compression mechanism 120 can be increased. Thereby, as is clear from the graph showing the relationship between the rotational speed of the compression mechanism and the compression efficiency of FIG. 16 described above, the compression efficiency of the high-stage compression mechanism 120 can be improved.

  In addition, when the rotation speed of the high-stage compression mechanism 120 becomes equal to or higher than a predetermined fourth reference rotation speed in a state where the second refrigerant circuit is switched, the two-stage booster refrigeration cycle 10 is required. Therefore, the control described in the above (b) is performed by switching to the third refrigerant circuit. Note that the fourth reference rotation speed is set to a value higher than the second reference rotation speed.

  Next, the cooling operation mode will be described. The cooling operation mode is started when the operation switch of the vehicle air conditioner is turned on (ON) and the cooling operation mode is selected by the selection switch. When the cooling operation mode is started, the operation mode control means switches the operation states of the intermediate pressure expansion valve 15a, the low pressure expansion valve 15b, the on-off valve 17 and the electric three-way valve 19 constituting the operation mode switching means.

  Specifically, the intermediate pressure expansion valve 15a and the low pressure expansion valve 15b are fully closed, the on-off valve 17 is opened, and the electric three-way valve 19 is connected to the outlet side of the outdoor heat exchanger 18 and the inlet side of the cooling expansion valve 15c. The refrigerant expansion circuit 15c is switched to a throttle state in which the refrigerant is decompressed and expanded, and the throttle passage area opening is set to a predetermined opening. Further, the refrigerant circuit control means closes the intermediate pressure side opening / closing valve 14a and the low pressure side opening / closing valve 22a constituting the refrigerant circuit switching means.

  As a result, the refrigerant flows as shown by solid line arrows in FIG. In this state, the air-conditioning control device reads the detection signal and the operation signal at every predetermined control cycle, calculates the target blowing temperature TAO, determines the operating state of various air-conditioning control devices, controls voltage and A control routine such as the output of a control signal is repeated until the vehicle air conditioner is requested to stop operating.

  At this time, in the two-stage booster refrigeration cycle 10, the high-pressure refrigerant discharged from the discharge port 146 of the compressor 100 flows into the indoor condenser 12 and dissipates heat. Thereby, the cold wind which passes the indoor condenser 12 among the cold wind which was ventilated from the air blower 32 and was cooled in the indoor evaporator 20 is heated.

  Since the first and second electric expansion valves 15a and 15b are fully closed and the on-off valve 17 is open, the high-pressure refrigerant that has flowed out of the indoor condenser 12 has the first three-way joint 13a → the on-off valve 17 → It flows in the order of the second three-way joint 13b and flows into the outdoor heat exchanger 18. The refrigerant flowing into the outdoor heat exchanger 18 is further cooled by exchanging heat with the outside air, and its enthalpy is lowered.

  The refrigerant that has flowed out of the outdoor heat exchanger 18 is switched to a refrigerant circuit in which the electric three-way valve 19 connects the outlet side of the outdoor heat exchanger 18 and the inlet side of the cooling expansion valve 15c, and the expansion for cooling is performed. Since the valve 15c is in the throttle state, it is decompressed and expanded at the cooling expansion valve 15c until it becomes a low-pressure refrigerant.

  The low-pressure refrigerant decompressed and expanded by the cooling expansion valve 15 c flows into the indoor evaporator 20, absorbs heat from the indoor air blown from the blower 32, and evaporates. Thereby, indoor ventilation air is cooled. The refrigerant that has flowed out of the indoor evaporator 20 flows into the accumulator 21 through the third three-way joint 13c and is separated into gas and liquid. The separated gas-phase refrigerant is sucked from the suction port 144 of the compressor 100 and compressed again.

  As described above, in the vehicle air conditioner 1 of the present embodiment, the indoor evaporator 20 is cooled by the indoor evaporator 20 and the opening degree of the air mix door 34 is adjusted in the cooling operation mode. The cold air cooled at 20 can be reheated by the indoor condenser 12, and the conditioned air at a temperature desired by the passenger can be blown out into the passenger compartment. Thereby, cooling of a vehicle interior is realizable.

  Furthermore, since the two-stage booster refrigeration cycle 10 of the present embodiment operates as described above, the following excellent effects can be obtained.

  According to the two-stage booster refrigeration cycle 10 of the present embodiment, the economizer refrigeration cycle can be configured by switching to the first refrigerant circuit in the heating operation mode, and both of them can be switched to the third refrigerant circuit. A refrigeration cycle that boosts the refrigerant in multiple stages in series in the compression mechanisms 110 and 120 can be configured, and single-stage compression that boosts the refrigerant in the high-stage compression mechanism 120 by switching to the second refrigerant circuit. A normal refrigeration cycle of the formula can be constructed.

  As the heating capacity required for the two-stage booster type refrigeration cycle 10 decreases, that is, the rotation speed of the compression mechanism decreases, the cycle configuration is changed in the order of the first refrigerant circuit → the third refrigerant circuit → the second refrigerant circuit. The cycle configuration is changed in the order of the second refrigerant circuit → the third refrigerant circuit → the first refrigerant circuit as the heating capacity required for the switching and the two-stage booster refrigeration cycle 10 increases, that is, as the rotational speed of the compression mechanism increases. Switching.

  Therefore, even if the heating capacity required for the two-stage booster refrigeration cycle 10 changes and the required circulating refrigerant flow rate changes, the COP of the two-stage booster refrigeration cycle 10 can be sufficiently improved. That is, COP can be sufficiently improved by configuring an economizer refrigeration cycle during normal operation or high load operation where the required circulating refrigerant flow rate is relatively high.

  Further, during low load operation where the required circulating refrigerant flow rate is lower than that during normal operation, a cycle is formed in which the refrigerant is boosted in multiple stages in the order of the low-stage compression mechanism 110 → the high-stage compression mechanism 120. By increasing the number of rotations, the COP can be improved by improving the compression efficiency of both the compression mechanisms 110 and 120.

  Furthermore, during extremely low load operation where the required circulating refrigerant flow rate is further reduced than during low load operation, a high-stage side compression mechanism 120 is configured to form a single-stage boost type refrigeration cycle in which the refrigerant is boosted by the high-stage side compression mechanism 120. By increasing the rotational speed of 120, the COP can be improved by improving the compression efficiency of the high-stage compression mechanism 120.

  As a result, as shown in FIG. 11, COP can be improved regardless of the heating capacity required for the two-stage booster refrigeration cycle 10, that is, regardless of the required circulating refrigerant flow rate.

  Further, in the two-stage booster refrigeration cycle 10 of the present embodiment, the rotation drive control means increases the rotation speed of the electric motor 130 as the heating capacity required for the two-stage booster refrigeration cycle 10 increases. Therefore, by switching the refrigerant circuit according to the rotation speed of the electric motor 130 (that is, the compression mechanism 110, 120), it is very easy to switch the refrigerant circuit according to the heating capacity required for the cycle. be able to.

  Further, in the compressor 100 of this embodiment and the like, the electric motor 130 rotationally drives both the compression mechanisms 110 and 120, so there is no need to individually control the rotation speeds of both the compression mechanisms 110 and 120. When the refrigerant circuit is switched, the rotational speeds of both the compression mechanisms 110 and 120 can be easily changed.

  Furthermore, since the both compression mechanisms 110 and 120 are arranged on both ends of the shaft 131 so as to sandwich the electric motor 130 from both sides in the horizontal direction, the compressor 100 as a whole can be reduced in size. As a result, the overall size of the two-stage booster refrigeration cycle 10 can be reduced.

  Further, in an electric vehicle to which the vehicle air conditioner 1 of the present embodiment is applied, the waste heat of the engine cannot be used for heating the passenger compartment as in a vehicle equipped with an internal combustion engine (engine). In the vehicle air conditioner applied to such a vehicle, the configuration in which the indoor blown air is heated using the refrigeration cycle depends on the required heating capacity as in the two-stage booster refrigeration cycle 10 of the present embodiment. It is extremely effective to exhibit a high COP.

  Further, the two-stage booster type refrigeration cycle 10 of the present embodiment may be applied to a so-called hybrid vehicle that obtains driving force for vehicle travel from an internal combustion engine (engine) EG and a travel electric motor. In a hybrid vehicle, the engine may be stopped for the purpose of improving fuel efficiency during traveling, and therefore it is effective to apply the two-stage booster refrigeration cycle 10 of the present embodiment. Of course, the two-stage booster type refrigeration cycle 10 of the present embodiment may be applied to a normal vehicle.

(Second Embodiment)
This embodiment demonstrates the example which changed the structure of the refrigerant circuit switching means with respect to 1st Embodiment. Specifically, in the present embodiment, as shown in the overall configuration diagram of FIG. 12, an electric three-way valve disposed as a refrigerant circuit switching unit at a connection portion between the intermediate pressure refrigerant passage 14 and the low pressure refrigerant passage 22. 22b is adopted.

  In FIG. 12, the same or equivalent parts as those in the first embodiment are denoted by the same reference numerals. The same applies to the following drawings. Moreover, in FIG. 12, the flow of the refrigerant | coolant at the time of switching to a 1st refrigerant circuit at the time of heating operation mode is shown by the solid line arrow.

  The three-way valve 22b is composed of a rotary valve whose operation is controlled by a control signal output from the air conditioning control device, and a refrigerant circuit (first refrigerant) that opens the intermediate pressure refrigerant passage 14 and closes the low pressure refrigerant passage 22. Circuit), a refrigerant circuit (second refrigerant circuit) that closes the intermediate-pressure refrigerant passage 14 and opens the low-pressure refrigerant passage 22, and a refrigerant circuit (third refrigerant circuit) that closes both the intermediate-pressure refrigerant passage 14 and the low-pressure refrigerant passage. Can be switched.

  Other configurations and operations are the same as those in the first embodiment. Therefore, also in the two-stage booster refrigeration cycle 10 of the present embodiment, the COP depends on the heating capacity required for the two-stage booster refrigeration cycle 10 as in the first embodiment, that is, regardless of the required circulating refrigerant flow rate. Can be improved.

(Third embodiment)
In this embodiment, the structure of the compressor 100 is changed with respect to 1st Embodiment. Specifically, in the present embodiment, as shown in the schematic configuration diagram of FIG. 13, an electromagnetic clutch 130 a serving as a power interrupting means is provided between the low-stage compression mechanism 110 and the electric motor 130 of the compressor 100. Provided. FIG. 13 shows only the compressor 100 in FIGS. 1 to 4 and 12 in an enlarged manner for clarity of illustration.

  Furthermore, in the present embodiment, when the first and third refrigerant circuits are switched, the low-stage compression mechanism 110 and the electric motor 130 are connected to the electromagnetic clutch 130a from the air conditioning control device to transmit power. When the control signal is output and switched to the second refrigerant circuit, the control signal is used to cut off power transmission from the low-stage compression mechanism 110 and the electric motor 130 to the electromagnetic clutch 130a from the air conditioning control device. Is output.

  Other configurations and operations are the same as those in the first embodiment. Therefore, also in the two-stage boost refrigeration cycle 10 of the present embodiment, the same effect as that of the first embodiment can be obtained. Further, since the rotational driving force is not transmitted from the electric motor 130 to the low-stage compression mechanism 110 that does not exhibit the refrigerant discharge capability when switched to the second refrigerant circuit, the sliding loss of the low-stage compression mechanism 110 is reduced. It can suppress and can improve COP still more.

(Fourth embodiment)
In the present embodiment, the configuration of the two-stage booster refrigeration cycle 10 is changed as shown in the overall configuration diagram of FIG. 14 with respect to the first to third embodiments. In FIG. 14, the flow of the refrigerant when switching to the first refrigerant circuit in the heating operation mode is indicated by a solid arrow.

More specifically, the refrigerant outlet of the first three-way joint 13 a via the low-pressure expansion valve 15b, as shown in FIG. 14 connected to the inlet side of the outdoor heat exchanger 18. Thus, the liquid-phase refrigerant | coolant exit of the gas-liquid separator 16 is abolished by changing the connection position of the low-pressure expansion valve 15b .

  In the heating operation mode, the operation mode control means sets the intermediate pressure expansion valve 15a and the low pressure expansion valve 15b constituting the operation mode switching means to the throttle state, and sets the throttle passage area opening degree to a predetermined opening degree. The three-way valve 19 is switched so as to connect the outlet side of the outdoor heat exchanger 18 and one refrigerant inlet of the third three-way joint 13c.

  Further, when switching to the first refrigerant circuit, as in the first embodiment, the refrigerant circuit control means opens the intermediate pressure side on / off valve 14a and closes the low pressure side on / off valve 22a. Thereby, with respect to the first embodiment, the low-pressure expansion valve 15b has a cycle in which the high-pressure refrigerant branched out by the first three-way joint 13a out of the high-pressure refrigerant flowing out of the indoor condenser 12 is reduced until it becomes a low-pressure refrigerant. Composed.

  When switching to the third refrigerant circuit, the refrigerant circuit control means closes the intermediate pressure side opening / closing valve 14a and closes the low pressure side opening / closing valve 22a. Thereby, the 3rd refrigerant circuit similar to a 1st embodiment is constituted. Further, when switching to the second refrigerant circuit, the refrigerant circuit control means closes the intermediate pressure side opening / closing valve 14a and opens the low pressure side opening / closing valve 22a. Thereby, the 2nd refrigerant circuit similar to 1st Embodiment is comprised.

  Other configurations and operations are the same as those in the first embodiment. Even if the low-pressure expansion valve 15b is configured to depressurize the high-pressure refrigerant directly into the low-pressure refrigerant when switched to the first refrigerant circuit as in the present embodiment, the two-stage boosting type is the same as in the first embodiment. COP can be improved regardless of the heating capacity required for the refrigeration cycle 10, that is, regardless of the required circulating refrigerant flow rate.

(Other embodiments)
The present invention is not limited to the above-described embodiment, and can be variously modified as follows without departing from the spirit of the present invention.

  (1) In each of the above-described embodiments, the example in which the two-stage booster type refrigeration cycle 10 of the present invention is applied to the vehicle air conditioner 1 has been described, but the application of the present invention is not limited to this. For example, the present invention may be applied to a stationary air conditioner, a cold storage container, and the like.

  Moreover, in each above-mentioned embodiment, although the two-stage pressure | voltage rise type refrigerating cycle 10 is used as a heat pump cycle which heats the indoor ventilation air which is a fluid for heat exchange in the indoor condenser 12, conversely, the indoor condenser 12 The heat quantity of the high-pressure refrigerant may be radiated to the atmosphere so that the outdoor heat exchanger 18 functions as a use-side heat exchanger that cools the heat exchange target fluid. And you may apply to the air conditioner which cools air-conditioning object space, such as a refrigeration device which cools the inside temperature to a very low temperature.

  In this case, as the cooling capacity of the heat exchange target fluid required for the two-stage booster refrigeration cycle 10 decreases, the first refrigerant circuit, the third refrigerant circuit, and the second refrigerant circuit may be switched in this order. . Note that it is extremely effective that a high COP can be exhibited regardless of the required cooling capacity in an apparatus in which the pressure difference between the high-pressure refrigerant and the low-pressure refrigerant is large and the power consumption of the compression mechanism is likely to be large, such as a refrigeration apparatus. .

  (2) In each of the above-described embodiments, the example in which the rolling piston type compression mechanism is employed as the low-stage compression mechanism 110 and the high-stage compression mechanism 120 has been described. Of course, other types of compression mechanisms are employed. May be. For example, a vane type compression mechanism, a reciprocating type compression mechanism, or a scroll type compression mechanism may be employed. Furthermore, different types of compression mechanisms may be employed as the low-stage compression mechanism 110 and the high-stage compression mechanism 120.

  Note that, as in the first, second, and fourth embodiments described above, in a configuration that does not employ the electromagnetic clutch 130a that cuts off power transmission between the low-stage compression mechanism 110 and the electric motor 130, the third refrigerant circuit In order to ensure that the refrigerant discharge capability of the low-stage compression mechanism 110 is not reliably exhibited when switching to, it is desirable not to employ a scroll-type compression mechanism as the low-stage compression mechanism 110.

  When a reciprocating compression mechanism is employed as the low-stage compression mechanism 110, the electromagnetic clutch 130a employed in the third embodiment may be eliminated and a fixing unit that fixes the movement of the piston may be employed.

  (3) In the above-described fourth embodiment, the example in which the gas-liquid separator 16 that performs gas-liquid separation of the intermediate-pressure refrigerant decompressed by the intermediate-pressure expansion valve 15a has been described, but the gas-liquid separator 16 is abolished. Then, an intermediate pressure heat exchanger that exchanges heat between the intermediate pressure refrigerant decompressed by the intermediate pressure expansion valve 15a and the high-pressure refrigerant flowing out from the other refrigerant outlet of the first three-way joint 13a may be employed.

  (4) In each of the above-described embodiments, the first refrigerant circuit → the third refrigerant circuit → the second refrigerant with a decrease in the heating capacity or cooling capacity of the heat exchange target fluid required for the two-stage booster refrigeration cycle 10. Although the example which switches a refrigerant circuit in order of a circuit was demonstrated, you may abolish switching to a 3rd refrigerant circuit.

  For example, when the heating capacity or the cooling capacity required for the two-stage booster refrigeration cycle 10 is equal to or lower than a predetermined second reference capacity, the second refrigerant circuit is directly switched from the first refrigerant circuit without switching to the third refrigerant circuit. When the heating capacity or the cooling capacity required for the two-stage booster refrigeration cycle 10 is equal to or higher than a predetermined first reference capacity, the second refrigerant circuit is switched to the third refrigerant circuit without switching to the third refrigerant circuit. You may make it switch to a 1st refrigerant circuit directly.

  (5) In the above-described embodiments, when switching from the third refrigerant circuit to the second refrigerant circuit, the rotation speed of the high-stage compression mechanism 120 is increased based on the discharge capacity ratio V2 / V1, but the high pressure As the side compression mechanism 120, it is desirable to employ one that operates as described below with the increase in the rotational speed.

  Here, the relationship among the rotational speed Nc, the required torque Tr, and the compression efficiency of the compression mechanism will be described with reference to FIG. FIG. 15A is an isoefficiency diagram showing a change in compression efficiency in accordance with the rotational speed Nc and required torque Tr of the compression mechanism, and FIG. 15B shows a change in compression efficiency with respect to the rotational speed Nc. It is a graph and the change of the compression efficiency in CC section and DD section of Drawing 15 (a) is indicated.

  Contour lines indicated by thick broken lines in FIG. 15 indicate necessary compression efficiency lines of the high-stage compression mechanism 120 necessary for sufficiently improving the COP of the two-stage booster refrigeration cycle 10. In other words, in order to sufficiently improve the COP of the two-stage booster refrigeration cycle 10, it is necessary to operate the compression mechanism in the area indicated by hatching on the left side of the required compression efficiency line in FIG. is there.

  Therefore, it is desirable that the high-stage compression mechanism 120 of the present embodiment employs a mechanism that operates in the region on the right side of the required compression efficiency line when the rotation speed is increased by switching to the second refrigerant circuit. . Thereby, when switching to a 2nd refrigerant circuit, COP of the two-stage pressure | voltage rise refrigerating cycle 10 can be improved sufficiently reliably.

Moreover, in order to implement | achieve this, you may determine the increase of the rotation speed of the high stage compression mechanism 120 at the time of switching to a 2nd refrigerant circuit as follows. That is, the relationship of the isoefficiency diagram of FIG. 15A is stored in the air conditioning control device in advance, and the detection signal of the sensor group for air conditioning control read immediately before switching from the third refrigerant circuit to the second refrigerant circuit is used. The required torque Tr immediately before switching from the third refrigerant circuit to the second refrigerant circuit is calculated. The required torque Tr can be obtained from the following formula F1.
Tr = (L × 60) / (2π × Nc) (F1)
Note that L is the required drive power of the high-stage compression mechanism 120 (in this embodiment, required power supplied to the electric motor 130).

Further, the required drive power L of the high-stage compression mechanism 120 can be expressed as a function of the discharge refrigerant pressure Pd, the suction refrigerant pressure Ps, and the rotation speed Nc of the high-stage compression mechanism 120 as shown in the following formula F2. .
L = f (Pd, Ps, Nc) (F2)
The relationship represented by the formula F2 is stored in advance in the air conditioning control device.

  Further, in the present embodiment, from the required torque Tr immediately before switching from the third refrigerant circuit to the second refrigerant circuit and the second reference rotational speed at which the third refrigerant circuit is switched to the second refrigerant circuit, the third refrigerant circuit to the second refrigerant. The compression efficiency of the high-stage compression mechanism 120 immediately before switching to the circuit is determined. For example, in FIG. 10A, the compression efficiency of the high stage compression mechanism 120 immediately before switching from the third refrigerant circuit to the second refrigerant circuit is represented by point E.

  Then, the number of rotations of the high-stage compression mechanism 120 that can shift the compression efficiency of the high-stage compression mechanism 120 from the point E to the point F existing in the region on the right side of the required compression efficiency line is determined. The rotational speed difference from the point may be an increase in the rotational speed of the high-stage compression mechanism 120 when switching to the second refrigerant circuit.

12 radiator 14 intermediate pressure refrigerant passage 14a intermediate pressure side opening / closing valve 15a intermediate pressure expansion valve 15b low pressure expansion valve 18 evaporator 22 low pressure refrigerant passage 22a low pressure side opening / closing valve 110 low stage side compression mechanism 120 high stage side compression mechanism 130 electric motor

Claims (4)

A low-stage compression mechanism (110) that compresses and discharges the low-pressure refrigerant until it becomes an intermediate-pressure refrigerant;
A high-stage compression mechanism (120) that compresses and discharges the intermediate-pressure refrigerant discharged from the low-stage compression mechanism (110) until it becomes a high-pressure refrigerant;
A radiator (12) for radiating high-pressure refrigerant discharged from the high-stage compression mechanism (120);
An intermediate pressure expansion valve (15a) for reducing the pressure of the refrigerant flowing out of the radiator (12) until it becomes an intermediate pressure refrigerant;
A low pressure expansion valve (15b) for reducing the pressure of the refrigerant flowing out of the radiator (12) until it becomes a low pressure refrigerant;
An evaporator (18) that evaporates the low-pressure refrigerant decompressed by the low-pressure expansion valve (15b) and flows out to the suction side of the low-stage compression mechanism (110);
A two-stage booster type refrigeration cycle comprising an intermediate pressure refrigerant passage (14) for guiding the intermediate pressure refrigerant decompressed by the intermediate pressure expansion valve (15a) to the suction side of the high stage compression mechanism (120). ,
A connection is established between the suction-side refrigerant passage connected to the suction side of the low-stage compression mechanism (110) and the intermediate-pressure refrigerant passage (14) connected to the suction side of the high-stage compression mechanism (120). A low-pressure refrigerant passage (22),
A first refrigerant circuit that opens the intermediate pressure refrigerant passage (14) and closes the low pressure refrigerant passage (22), and a second refrigerant that closes the intermediate pressure refrigerant passage (14) and opens the low pressure refrigerant passage (22). Refrigerant circuit switching means (14a, 22a ) for switching circuits ;
An electric motor (130) that rotationally drives both the high-stage compression mechanism (120) and the low-stage compression mechanism (110) ,
Furthermore, the discharge capacity (V2) of the high stage compression mechanism (120) is set smaller than the discharge capacity (V1) of the low stage compression mechanism (110),
The refrigerant circuit switching means includes an intermediate pressure side on / off valve (14a) for opening / closing the intermediate pressure refrigerant passage (14) and a low pressure side on / off valve (22a) for opening / closing the low pressure refrigerant passage (22). A featured two-stage booster refrigeration cycle. Refrigerant circuit control means for controlling the operation of the refrigerant circuit switching means (14a, 22a ) ,
The refrigerant circuit control means (14a, 22a ) switches the refrigerant circuit so as to switch to the first refrigerant circuit when the cooling capacity or heating capacity required for the cycle exceeds a predetermined first reference capacity. And the refrigerant circuit switching means (14a, 22a) so as to switch to the second refrigerant circuit when the cooling capacity or heating capacity required for the cycle falls below a predetermined second reference capacity. two-stage booster type refrigeration cycle according to claim 1, characterized in that to control the operation of). Rotation drive control means for controlling the operation of the electric motor (130),
The rotational drive control means controls to increase the rotational speed of the electric motor (130) as the cooling capacity or heating capacity required for the cycle increases.
The refrigerant circuit control means (14a, 22a ) switches the refrigerant circuit control means to switch to the first refrigerant circuit when the rotational speed of the electric motor (130) becomes equal to or higher than a predetermined first reference rotational speed. And the refrigerant circuit switching means (14a, 22a) so as to switch to the second refrigerant circuit when the rotational speed of the electric motor (130) becomes equal to or lower than a predetermined second reference rotational speed. two-stage booster type refrigeration cycle according to claim 2, characterized in that to control the operation of). Further, the refrigerant circuit switching means (14a, 22a ) is configured to be switchable to a third refrigerant circuit that closes the intermediate pressure refrigerant passage (14) and closes the low pressure refrigerant passage (22). The two-stage booster type refrigeration cycle according to any one of claims 1 to 3.

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