JP2010032157A - Refrigeration cycle device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a refrigeration cycle device providing refrigerating capacity not so different from the existing refrigerant while providing advantage of a new refrigerant, and not impairing durability. <P>SOLUTION: This refrigeration cycle device 100A includes an internal heat exchanger 160 and uses a circulating refrigerant R0. Inclination of the isentropic line EL0 of the circulating refrigerant R0 is larger than that of the isentropic line ELC of a refrigerant R134a. This characteristic suppresses temperature rise of the refrigerant in a compressor 110. The enthalpy width ED0 in the two-phase region of the circulating refrigerant R0 is narrower than the enthalpy width EDC of the refrigerant R134a. The internal heat exchanger 160 increases an enthalpy width EH on a cycle CY. Even the refrigerant R0 having narrow enthalpy width exhibits a required refrigerating capacity by the internal heat exchanger 160. Besides, it is possible to suppress excessive temperature rise of the refrigerant in the compressor 110 and avoid impairment of durability. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a refrigeration cycle apparatus.

  As described in Patent Documents 1 to 4, a new refrigerant has been proposed that focuses on the global warming potential GWP. These new refrigerants have the advantage of low GWP. However, refrigeration capacity comparable to that of existing refrigerants and ease of replacement with existing refrigerants are required.

On the other hand, a refrigeration cycle apparatus described in Patent Document 5 is known. This refrigeration cycle apparatus includes an internal heat exchanger that exchanges heat between the high-pressure refrigerant between the condenser and the expansion valve and the low-pressure refrigerant between the evaporator and the compressor. Further, in this refrigeration cycle apparatus, a normal charge expansion valve is used to control the state of the refrigerant at the evaporator outlet from a dryness of 0.9 to a superheat of 5 ° C. Such a numerical range provides liquid side biased control.
Special table 2008-505111 JP 2008-111578 A Special table 2007-538115 gazette Special table 2007-535611 gazette JP 2007-71461 A

  According to the invention described in Patent Document 5, it is possible to keep the intake temperature of the compressor low even if an internal heat exchanger is provided. As a result, even if the refrigerant temperature rises inside the compressor, the discharge temperature of the compressor can be kept low. For this reason, it is possible to avoid exposing rubber parts, resin parts, electronic parts, and the like around the compressor to high temperatures, and it is possible to suppress a decrease in durability of the parts. On the other hand, the gas-liquid two-phase refrigerant sometimes flows out to the outlet of the evaporator, and the opening degree of the expansion valve causes a hunting phenomenon. Thus, in the refrigeration cycle apparatus that employs a refrigerant that is already widely available on the market, attempts have been made to improve the refrigeration capacity. However, there is a problem that a new problem becomes apparent as the refrigeration capacity is improved.

  The present invention has been made in view of the above-mentioned problems of the prior art, and an object thereof is to provide a refrigeration cycle apparatus in which both the refrigeration capacity and the durability are comprehensively improved.

  In view of the above-described problems of the prior art, the present invention provides a refrigeration cycle apparatus that suppresses an excessive increase in the refrigerant temperature while sufficiently drawing out the refrigeration capacity of the refrigeration cycle apparatus including an internal heat exchanger. The purpose.

  Another object of the present invention is to provide a refrigeration cycle apparatus that can obtain the refrigeration capacity that is not significantly different from existing refrigerants while obtaining the advantages of the new refrigerant, and that does not impair the durability.

  In order to achieve the above object, the present invention employs the following technical means.

  According to the first aspect of the present invention, in the refrigeration cycle apparatus including the compressor (110, 210), the condenser (120), the expansion valve (131, 231, 331), and the evaporator (141), the condenser ( 120) and an internal heat exchanger (160) for exchanging heat between the high-pressure refrigerant between the expansion valves (131, 231, 331) and the low-pressure refrigerant between the evaporator (141) and the compressors (110, 210). ) And the circulating refrigerant circulating in the refrigeration cycle, the slope of the isentropic curve (EL0) on the ph diagram is larger than the isentropic curve (ELC) of the refrigerant R134a, and the two-phase region on the ph diagram The enthalpy width (ED0) includes a circulating refrigerant (R0) narrower than the enthalpy width (EDC) of the refrigerant R134a. According to the present invention, the refrigeration capacity of the circulating refrigerant (R0) is sufficiently extracted by providing the internal heat exchanger. On the other hand, using the characteristics of the circulating refrigerant (R0), the refrigerant temperature can be kept low to such an extent that the durability of the components of the refrigeration cycle apparatus is not impaired. As a result, the options for the circulating refrigerant can be expanded, and for example, a circulating refrigerant having characteristics not found in the widely circulating refrigerant R134a can be used.

  In the second aspect of the present invention, the enthalpy width (ED0) of the two-phase region of the circulating refrigerant (R0) at the saturation temperature 0 ° C. on the ph diagram is equal to the enthalpy width (EDC) of the two-phase region of the refrigerant R134a. The internal heat exchanger (160) has a enthalpy width of the condensation process or evaporation process on the ph diagram, and the two-phase region of the circulating refrigerant (R0) at a saturation temperature of 0 ° C. on the ph diagram. The enthalpy width (ED0) is set to increase by 5% or more (EH). According to the present invention, the refrigeration capacity can be sufficiently extracted by providing the internal heat exchanger.

  In the invention according to claim 3, the enthalpy width (ED0) of the two-phase region of the circulating refrigerant (R0) at the saturation temperature 0 ° C. on the ph diagram is equal to the enthalpy width (EDC) of the two-phase region of the refrigerant R134a. The internal heat exchanger (160) has an enthalpy width of the condensation process or evaporation process on the ph diagram, and a circulating refrigerant at a saturation temperature of 0 ° C. on the ph diagram. It is set to increase (EH) within a range of 5% to 10% with respect to the enthalpy width (ED0) of the two-phase region of (R0). According to the present invention, the refrigeration capacity can be sufficiently extracted by providing the internal heat exchanger.

  In the invention according to claim 4, the isentropic line (EL0) of the circulating refrigerant (R0) passing through the intersection of the saturation temperature of 0 ° C. and the saturated gas line has an inclination in the range of 0.044 or more and 0.054 or less. It is characterized by having. According to the present invention, even if an internal heat exchanger is provided, an excessive increase in the refrigerant temperature inside the compressor (110, 210) can be suppressed.

  According to the invention described in claim 5, the circulating refrigerant (R0) is a mixed refrigerant including at least one low GWP refrigerant. According to the present invention, it is possible to improve both the refrigerating capacity and the durability while obtaining the advantage of the low GWP of the circulating refrigerant R0.

  In the invention according to claim 6, the expansion valves (131, 231) control the superheat degree (SH) of the refrigerant at the outlet of the evaporator (141) to a target value within a range of 0 ° C to 6 ° C. It has a normal charge characteristic (EV1, EV3) set to be. According to this invention, the improvement effect of the refrigerating capacity by an internal heat exchanger (160) can be acquired reliably.

  The invention according to claim 7 is characterized in that the compressor (210) includes an electric motor (212) and a control circuit (213) mounted so as to receive the heat of the refrigerant. According to this invention, it is suppressed that the durability of the electronic circuit component contained in the control circuit (213) is impaired.

  In the invention according to claim 8, the expansion valve (331) has a superheat degree (SH) of the refrigerant at the outlet of the evaporator (141) in the range of 0 ° C. or more and 6 ° C. or less within the normal operation region. It has a cross charge characteristic (EV4) set to be controlled within. According to the present invention, it is possible to reliably obtain the effect of improving the refrigerating capacity by the internal heat exchanger (160) while obtaining the advantage of the cross charge characteristic (EV4).

  In the invention according to claim 9, the normal operation range corresponds to a range in which the refrigerant pressure (P) at the outlet of the evaporator (141) is 0.2 MPaG or more and 0.3 MPaG or less, and the cross charge characteristic (EV4) is When the pressure (P) of the refrigerant at the outlet of the evaporator (141) is 0.3 MPaG, the superheat degree (SH) of the refrigerant at the outlet of the evaporator (141) is set to be controlled to 0 ° C. It is characterized by being. According to the present invention, a refrigeration cycle apparatus suitable for application to a cooling apparatus is provided.

  The invention according to claim 10 is characterized in that the refrigeration cycle apparatus (100A, 200A, 300A) is used in a vehicle air conditioner, and the internal heat exchanger (160) is a double pipe. According to this invention, an internal heat exchanger is provided by the double pipe which serves as piping.

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

(First embodiment)
Hereinafter, a first embodiment in which the present invention is applied to a cooling refrigeration cycle apparatus 100A for a vehicle air conditioner 100 will be described.

  1 and 2, the vehicle is partitioned by a dash panel 3 into an engine room 1 in which a traveling engine 10 is mounted and a passenger compartment 2. The refrigeration cycle apparatus 100 </ b> A is disposed across the engine room 1 and the vehicle compartment 2. The indoor unit 100 </ b> B of the air conditioner 100 is disposed in the instrument panel of the passenger compartment 2.

  The indoor unit 100B has an air conditioning case 101. In the air conditioning case 101, a blower 102, an evaporator 141, a heater core 103, and the like are disposed. The blower 102 selectively takes in outside air or inside air of the vehicle as conditioned air and blows the conditioned air to the evaporator 141 and the heater core 103. The evaporator 141 is a cooling heat exchanger that evaporates the circulating refrigerant of the refrigeration cycle apparatus 100A and cools the conditioned air. The heater core 103 is a heat exchanger for heating that heats conditioned air using hot water of the engine 10 as a heating source.

  An air mix door 104 is provided in the vicinity of the heater core 103. The air mix door 104 adjusts the mixing ratio between the conditioned air cooled by the evaporator 141 and the conditioned air heated by the heater core 103. The blowing temperature is adjusted by the air mix door 104, and the temperature in the passenger compartment is adjusted to the set temperature.

  The refrigeration cycle apparatus 100A includes a compressor 110, a condenser 120, an expansion valve 131, and an evaporator 141. These parts are sequentially connected by a plurality of pipes 150 to form a closed circuit. A hose including a rubber layer and a resin layer is used on the suction side and the discharge side of the compressor 110. An internal heat exchanger 160 is provided for exchanging heat between the high-pressure refrigerant between the condenser 120 and the expansion valve 131 and the low-pressure refrigerant between the evaporator 141 and the compressor 110.

  The compressor 110 compresses the circulating refrigerant to a high temperature and a high pressure. The compressor 110 is driven by the driving force of the engine 10. A pulley 111 with an electromagnetic clutch is fixed to the drive shaft of the compressor 110. The driving force of the engine 10 is transmitted to the pulley 111 via the crank pulley 11 and the driving belt 12. The pulley 111 is provided with an electromagnetic clutch that intermittently connects between the compressor drive shaft and the pulley 111. The compressor 110 is a variable capacity compressor.

  The capacity of the compressor 110 is controlled by the control device 105. The control device 105 stores a target pressure set in advance according to the load. For example, the control device 105 controls the capacity so that the evaporation pressure of the evaporator 141 matches the target pressure. For example, the control device 105 controls the capacity so as to maintain the evaporation pressure within a range of 0.2 MPa or more and 0.3 MPa or less. In this embodiment, the surface temperature of the evaporator 141 is detected by the temperature sensor 106. The control device 105 controls the capacity so as to maintain the temperature detected by the temperature sensor 106 at the target temperature. Furthermore, the control device 105 performs intermittent operation in a low load region in order to avoid continuation of low capacity operation for a long time. The control device 105 is intermittently operated between the variable capacity control means for continuously adjusting the capacity of the compressor 110 in the medium load area and the high load area, and the capacity state capable of maintaining the oil return in the low load area and the stopped state. And an intermittent control means. The intermittent operation is realized by intermittently engaging the electromagnetic clutch or changing the capacity to a larger or smaller value. As a result, oil return in a low load state is ensured.

  The condenser 120 is a high-pressure side heat exchanger. The condenser 120 is connected to the discharge side of the compressor 110. The condenser 120 condenses and liquefies the refrigerant by heat exchange with the outside air. The expansion valve 131 is a pressure reducer and may be provided by a throttle, a valve, an ejector, or the like. The expansion valve 131 decompresses and expands the liquid-phase refrigerant that has flowed out of the condenser 120 to reduce the pressure in an isenthalpy manner. The expansion valve 131 is provided in the vicinity of the evaporator 141. The expansion valve 131 is a temperature-sensitive expansion valve that controls the throttle opening so that the refrigerant state at the outlet of the evaporator 141 becomes a predetermined state. The evaporator 141 is a low-pressure side heat exchanger and is also called a cooler or a heat absorber. The refrigerant outlet of the evaporator 141 is connected to the suction side of the compressor 110 via a pipe 150 and a double pipe 160.

  The double pipe 160 is an internal heat exchanger in which an inner pipe 162 is disposed in an outer pipe 161. The double pipe 160 also serves as a pipe. The double pipe 160 is laid long along the front-rear direction in the engine room 1. The double pipe 160 is bent at a plurality of locations for laying. A low-pressure refrigerant flows in the inner pipe 162. A high-pressure refrigerant flows between the outer tube 161 and the inner tube 162. The double tube 160 has a length of about 300 mm to 800 mm. The wall surface of at least the inner tube 162 of the double tube 160 is provided with a spiral groove shape as a shape that promotes heat exchange in order to realize a required heat exchange amount in the above length. The double pipe 160 also functions as a pipe. For this reason, it can be laid in the narrow engine room 1 of the vehicle. Moreover, the double pipe 160 is effective for reducing the adverse effects of the high temperature air in the engine room 1.

  The expansion valve 131 will be described with reference to FIG. The expansion valve 131 has a block-shaped housing and is called a box type. The expansion valve 131 includes a valve portion 131a that adjusts the amount of refrigerant supplied to the evaporator 141, and a temperature sensing portion 131b that adjusts the opening degree of the valve portion 131a. The valve portion 131a can be configured by a valve seat, a valve body, and a valve closing spring. The temperature sensing unit 131b includes a unit that senses the refrigerant state at the outlet of the evaporator 141, a control unit that generates an operation amount of the valve unit 131a so that the refrigerant state matches the target state, and a valve unit 131a according to the operation amount. Driving means for adjusting the opening degree of the. In this embodiment, the temperature sensing part 131b is a fluid pressure type power element. The power element includes a diaphragm as a pressure sensitive member. The diaphragm partitions the first chamber and the second chamber. A valve rod for driving the valve body is connected to the diaphragm. The diaphragm is displaced by the differential pressure between the first chamber and the second chamber, and adjusts the opening of the valve portion 131a. The evaporation pressure of the circulating refrigerant in the evaporator 141 is introduced into the first chamber. A medium is sealed in the second chamber. The medium includes a two-phase sealed refrigerant and an adjustment auxiliary gas. The enclosed refrigerant has a saturated vapor pressure curve having a larger slope than the saturated vapor pressure curve of the circulating refrigerant. The temperature of the refrigerant at the outlet of the evaporator 141 is transmitted to the medium in the second chamber. As a result, the enclosed refrigerant senses the refrigerant temperature at the outlet of the evaporator 141. The enclosed refrigerant changes the pressure in the second chamber depending on the refrigerant temperature at the outlet of the evaporator 141. Therefore, the diaphragm is displaced according to the differential pressure between the evaporation pressure of the evaporator 141 and the pressure corresponding to the temperature of the circulating refrigerant at the outlet of the evaporator 141.

  The circulating refrigerant R0 circulating in the refrigeration cycle apparatus 100A is a mixed refrigerant. The circulating refrigerant R0 contains at least one component refrigerant having a low GWP. The circulating refrigerant R0 can be created by mixing a plurality of already known refrigerants. The characteristic of the circulating refrigerant R0 is specified using R134a, which is a representative refrigerant widely distributed in the market, as a reference refrigerant.

  The characteristics of the circulating refrigerant R0 will be described with reference to FIG. FIG. 4 is called a ph diagram or a Mollier diagram. The horizontal axis in FIG. 4 indicates enthalpy H, and the vertical axis indicates pressure P. In FIG. 4, the saturation characteristic ML0 of the circulating refrigerant R0 is shown by a solid line. The saturation characteristic MLC of the reference refrigerant R134a is illustrated by a broken line.

  The saturated liquid line of the saturation characteristic ML0 is almost the same as the saturated liquid line of the saturation characteristic MLC. The critical pressure of saturation characteristic ML0 is lower than the critical pressure of saturation characteristic MLC. The saturated gas line with the saturation characteristic ML0 is located on the lower enthalpy side than the saturated gas line with the saturation characteristic MLC. When compared with the enthalpy width of the two-phase region between the saturated liquid line and the saturated gas line at the same pressure, the enthalpy width of the saturation characteristic ML0 is clearly narrower than the enthalpy width of the saturation characteristic MLC. At a pressure corresponding to a saturation temperature of 0 ° C., the enthalpy width ED0 of the saturation characteristic ML0 is about 80% of the enthalpy width EDC of the saturation characteristic MLC. Therefore, the enthalpy width of the circulating refrigerant R0 is −20% with respect to the enthalpy width of the reference refrigerant R134a. For this reason, when circulating refrigerant | coolant R0 is employ | adopted as the refrigeration cycle apparatus which is not equipped with an internal heat exchanger, sufficient refrigerating capacity cannot be obtained in an evaporation process.

  FIG. 4 shows an isentropic line passing through the intersection of the saturation temperature 0 ° C. and the saturated gas line. The isentropic line EL0 of the circulating refrigerant R0 is illustrated by a one-dot chain line, and the isentropic line ELC of the reference refrigerant R134a is illustrated by a two-dot chain line. The isentropic line EL0 shows a larger slope in the practical pressure range as the refrigeration cycle apparatus than the isentropic line ELC. The isentropic line EL0 has a slope of 0.049 between 0.3 MPa and 2.0 MPa. The slope is P / H = MPa / (kJ / kg). The isentropic line ELC has a slope of 0.040 between 0.3 MPa and 2.0 MPa. Since the compressor 110 pressurizes the refrigerant substantially along the isentropic line, when the same compressor is used, the circulating refrigerant R0 exhibits higher compressor efficiency than the reference refrigerant R134a. For this reason, in the circulating refrigerant R0, the temperature rise of the refrigerant in the compression process is small, and the discharge temperature from the compressor 110 is also kept low.

  The refrigeration cycle apparatus 100A draws a cycle CY illustrated in FIG. 4, for example. On the cycle CY, the condensation process is extended by the enthalpy width EH by the internal heat exchanger 160. Similarly, the evaporation process is extended by the enthalpy width EL by the internal heat exchanger 160. Therefore, the enthalpy width contributing to the cooling action in the evaporator 141 increases by the enthalpy width EH. The increase amount EH of the enthalpy width in the condensation process of the cycle CY corresponds to about 6% of the enthalpy width ED0 in the two-phase region of the circulating refrigerant R0. The heat exchange capacity of the internal heat exchanger 160 is set so as to give the increased amount EH. In other words, the double pipe 160 is set to increase the ethane loop width of the evaporation process of the cycle CY under the high load idle operation state by about 8%. The double pipe 160 can have heat exchange performance that raises the temperature of the low-pressure refrigerant within a range of 5.0 ° C. or higher and 15.0 ° C. or lower.

  The valve opening characteristics of the expansion valve 131 will be described with reference to FIG. FIG. 5 is called a pt diagram. In FIG. 5, the horizontal axis indicates the temperature T, and the vertical axis indicates the pressure P. A saturated vapor pressure curve SV0 of the circulating refrigerant R0 is indicated by a solid line. The saturated vapor pressure curve SVC of the reference refrigerant R134a is indicated by a broken line. The control characteristic EV1 of the expansion valve 131 is indicated by a one-dot chain line. The control characteristic EV2 as a comparative example is indicated by a two-dot chain line. The illustrated control characteristic EV1 is a characteristic called normal charge. The normal charge characteristic is given by having a saturated vapor pressure curve that is the same as or similar to that of the circulating refrigerant R0. The control characteristic EV1 is a curve obtained by substantially translating the saturated vapor pressure curve SV0 of the circulating refrigerant R0 on the pt diagram. The control characteristic EV1 gives a superheat degree of about 5 ° C. to the refrigerant at the outlet of the evaporator 141 in almost the entire operation region of the refrigeration cycle apparatus 100A. FIG. 5 shows that the degree of superheat of 5 ° C. is given at the evaporation pressure when the temperature of the temperature sensing part of the expansion valve 131 is approximately 0 ° C.

  The relationship between the cooling capacity Q and the superheat degree SH will be described with reference to FIG. The cooling capacity corresponds to the freezing capacity. The horizontal axis in FIG. 6 represents the superheat degree SH, and the vertical axis represents the cooling capacity Q. In this embodiment including the internal heat exchanger 160, the circulating refrigerant R0 exhibits the cooling capacity of the capacity curve CP0. On the other hand, when the internal heat exchanger 160 is not provided, the circulating refrigerant R0 exhibits the cooling capacity of the capacity curve CPC. The capability curve CP0 is higher than the capability curve CPC. Such a difference in cooling capacity is considered to be caused by the following two causes. The first cause is that the heat exchange efficiency on the low-pressure gas side in the internal heat exchanger 160 is improved in the range where the superheat degree SH is 0 ° C. or more. The second cause is that the enthalpy reference temperature efficiency of the evaporator 141 is improved when the degree of superheat SH is 0 ° C. or more. This phenomenon is understood from the fact that the capability Qea in the evaporator 141 is expressed by Qea = φ · Gea · (ia−ir). Here, φ is efficiency, Gea is the air volume, ia is the inlet side air enthalpy, and ir is the saturated air enthalpy corresponding to the refrigerant temperature.

  As can be understood from FIG. 6, in order to obtain a significant cooling capacity improvement amount QD, the superheat degree SH is desirably 7 ° C. or less. The upper limit of the degree of superheat SH can be 6 ° C or 5 ° C. Further, in order to ensure a stable oil return to the compressor, it is desirable that the degree of superheat SH be 7 ° C. or less. Stable oil return means that, for example, oil return to the compressor is observed within one minute in a wide operation region including a low load region. The upper limit of the degree of superheat SH that ensures oil return can be 6 ° C or 5 ° C. On the other hand, the lower limit of the superheat degree SH is preferably set to 0 ° C. or more so that the expansion valve 131 performs stable control without hunting. The lower limit of the superheat degree SH can be set to 0.5 ° C or 1 ° C. Furthermore, the lower limit of the superheat degree SH may be set higher than 1 ° C. where the peak value of the cooling capacity Q is observed in consideration of control stability. For example, the lower limit of the superheat degree SH can be 2 ° C or 3 ° C. The superheat degree SH is desirably controlled to a temperature within the range of the lower limit temperature to the upper limit temperature described above. For example, the superheat degree SH can be in the range of 0 ° C. or more and 6 ° C. or less. Furthermore, in order to provide stable control, it is desirable to adopt a value on the high temperature side even within the above range.

  Next, the operation of this embodiment will be described. When there is an air conditioning request from an occupant, for example, a cooling request, the compressor 110 is driven by the engine 10 and the refrigeration cycle apparatus 100A starts operation. As a result, the temperature of the evaporator 141 decreases. On the other hand, the air blown from the blower 102 is cooled by the evaporator 141, the temperature is adjusted, and the air is supplied to the vehicle interior.

  During operation of the refrigeration cycle apparatus 100A, the refrigerant state at the outlet of the evaporator 141 is controlled by the expansion valve 131. The expansion valve 131 maintains the superheat degree SH of the refrigerant at the outlet of the evaporator 141 at about 5 ° C. As a result, the effect of improving the cooling capacity by the internal heat exchanger 160 can be obtained. Moreover, since the degree of superheat SH is set to a relatively large value of about 5 ° C., the opening degree of the expansion valve 131 is prevented from causing a hunting phenomenon, and the control state of the expansion valve 131 is stabilized.

  The refrigerant exiting the evaporator 141 is further superheated by the internal heat exchanger 160. For this reason, the suction temperature of the compressor 110 reaches a relatively high temperature. This overheated refrigerant is sucked into the compressor 110 and compressed. However, the slope of the isentropic line EL0 of the circulating refrigerant R0 is larger than the slope of the isentropic line ELC of the reference refrigerant R134a. For this reason, the rise in the refrigerant temperature in the compressor 110 is less in the case of the circulating refrigerant R0 than in the case of the refrigerant R134a. As a result, the discharge temperature when the circulating refrigerant R0 is used is suppressed to a value equal to or lower than that when the reference refrigerant R134a is used. That is, it is avoided that the temperature of the refrigerant rises excessively inside and downstream of the compressor 110. Accordingly, it is possible to avoid impairing the durability of rubber or resin parts such as O-rings, hoses, and electrical parts from the suction part to the discharge part of the compressor 110.

  During the operation of the refrigeration cycle apparatus 100A, the flow rate of the circulating refrigerant R0 is about 20% higher than that of the refrigeration cycle apparatus using the reference refrigerant R134a. This difference in the refrigerant flow rate is attributed to the high low-pressure vapor density of the circulating refrigerant R0. Furthermore, the internal heat exchanger 160 increases the enthalpy width of the cycle CY. As a result, the refrigeration cycle apparatus 100A of this embodiment exhibits a cooling capacity that is not much different from the case where the reference refrigerant R134a is used.

  The effect of this embodiment will be described with reference to FIG. FIG. 7 shows the cooling capacity Q and the discharge temperature TD. FIG. 7 shows a state where the vehicle is stopped and the engine 10 is idling as IDLE, and a state where the vehicle is traveling stably is shown as DRIVE. The cooling capacity Q is set to 100 when the reference refrigerant R134a is used in a refrigeration cycle apparatus without an internal heat exchanger. A case where the circulating refrigerant R0 is used in a refrigeration cycle apparatus without an internal heat exchanger and a case where the circulating refrigerant R0 is used in a refrigeration cycle apparatus having an internal heat exchanger 160 as in this embodiment are shown. The cooling capacity Q when the circulating refrigerant R0 is used in a refrigeration cycle apparatus without an internal heat exchanger is lower than when the reference refrigerant R134a is used. However, in this embodiment including the internal heat exchanger 160, a cooling capacity slightly higher than that of the reference refrigerant R134a is obtained. In addition, the circulating refrigerant R0 lowers the discharge temperature TD by about 10 ° C. compared to the reference refrigerant R134a. For this reason, in this embodiment, although the internal heat exchanger 160 is provided, a discharge temperature TD equal to or lower than that of the reference refrigerant R134a is obtained.

  In this embodiment, the circulation refrigerant R0 in which the slope of the isentropic line on the ph diagram is larger than that of the reference refrigerant R134a and the enthalpy width of the two-phase region on the ph diagram is narrower than that of the reference refrigerant R134a is adopted. The cycle device includes an internal heat exchanger 160. For this reason, it is possible to obtain a cooling capacity that is not significantly different from the reference refrigerant R134a while avoiding the discharge temperature from becoming excessively high. Furthermore, since the expansion valve 131 has a normal charge characteristic, the cooling capacity improvement effect by the internal heat exchanger 160 can be obtained over the entire operation region.

  According to this embodiment, the refrigerant temperature can be kept low to such an extent that the durability of the components of the refrigeration cycle apparatus is not impaired while sufficiently extracting the refrigeration capacity by providing the internal heat exchanger. For this reason, the choice of a refrigerant | coolant can be expanded. In this embodiment, the advantage of the circulating refrigerant R0 including the low GWP component refrigerant can be obtained. As a result, it is possible to improve both the refrigerating capacity and the durability while taking advantage of the circulating refrigerant R0.

(Second Embodiment)
A second embodiment will be described with reference to FIG. The same components as those in FIG. 1 are denoted by the same reference numerals, and differences will be described. The refrigeration cycle apparatus 200A includes a compressor 210 driven by an electric motor instead of the compressor 110 driven by the engine. The compressor 210 includes a compression mechanism 211 and an electric motor 212. The compression mechanism 211 and the electric motor 212 are integrated so as to form a series of housings. The compressor 210 has a refrigerant suction port on the electric motor 212 side. The compressor 210 is integrally mounted with a control circuit 213 for driving the electric motor 212.

  The control circuit 213 is thermally coupled to the compressor 210, and the control circuit 213 receives the heat of the refrigerant. Control circuit 213 includes an inverter circuit. The control circuit 213 includes electronic circuit components such as switching elements, photocouplers, and IC elements. The control circuit 213 includes electronic circuit components having a relatively low heat resistant temperature. For example, the heat resistant temperature of the photocoupler is about 100 ° C to 110 ° C. For this reason, it is effective to keep the temperature of the electronic circuit components low in order to avoid a decrease in the durability of the compressor 210.

  A refrigerant passage that reaches the compression mechanism 211 through the electric motor 212 is formed in the compressor 210. This refrigerant passage provides a cooling means for the electric motor 212 and the control circuit 213. Each part of the compressor 210 is configured so that it can also be used for the reference refrigerant R134a. For this reason, the compressor 210 can be used for the refrigeration cycle apparatus using the reference refrigerant R134a and the refrigeration cycle apparatus using the circulating refrigerant R0.

  A control characteristic EV3 of the expansion valve 231 will be described with reference to FIG. The expansion valve 231 has a normal charge characteristic EV3 set so as to control the superheat degree SH of the refrigerant at the outlet of the evaporator 141 to 2 ° C.

  Next, the operation of this embodiment will be described. When the electric motor 212 is driven, the circulating refrigerant R0 circulates in the refrigeration cycle apparatus 200A. The circulating refrigerant R0 flowing into the electric motor 212 cools the electric motor 212 and the control circuit 213. While the refrigeration cycle apparatus 200A is in operation, the expansion valve 231 controls the degree of superheat of the refrigerant at the outlet of the evaporator 141 to 2 ° C. The internal heat exchanger 160 further superheats the refrigerant. However, since the superheat degree of the refrigerant at the outlet of the evaporator 141 is 2 ° C., the intake temperature of the compressor 210 can be kept relatively low even if the internal heat exchanger 160 is provided. In particular, the expansion valve 231 controls the refrigerant state at the outlet of the evaporator 141 so that the suction temperature at the suction port of the compressor 210 does not exceed the heat resistance temperature of the electronic circuit components of the control circuit 213. For example, the expansion valve 231 controls the degree of superheat SH so that the suction temperature does not exceed 100 ° C. to 110 ° C., which is the heat resistant temperature of the photocoupler accommodated in the control circuit 213.

  According to this embodiment, it is possible to provide a refrigeration cycle apparatus that uses the circulating refrigerant R0 by using the compressor 210 that can also be used as the reference refrigerant R134a. Moreover, by providing the internal heat exchanger 160, the refrigerant temperature can be kept low to such an extent that the durability of the components of the refrigeration cycle apparatus 200A is not impaired while sufficiently extracting the refrigeration capacity. As a result, it is possible to improve both the refrigerating capacity and the durability while taking advantage of the circulating refrigerant R0.

  The control characteristic of the expansion valve 231 can be set so that the superheat degree SH matches the target temperature within the range of 0 ° C. or more and 6 ° C. or less. When the superheat degree SH exceeds 6 ° C., the heat resistance temperature of the electronic circuit components of the compressor 210 may be exceeded. In order to achieve both high refrigeration capacity and control stability, the lower limit of the superheat degree SH in the control characteristics of the expansion valve 231 may be 1 ° C. Furthermore, the upper limit of the superheat degree SH may be 3 ° C. The control characteristic EV3 of the expansion valve 231 may be set so as to control the degree of superheat SH to 5 ° C.

(Third embodiment)
A third embodiment will be described with reference to FIG. The same components as those in FIG. 1 are denoted by the same reference numerals, and differences will be described. The refrigeration cycle apparatus 300A includes an expansion valve 331. A control characteristic EV4 of the expansion valve 331 will be described with reference to FIG. The expansion valve 331 has a cross charge characteristic. The cross charge characteristic intersects with the saturated vapor pressure curve of the circulating refrigerant R0, and provides a superheat degree in a high temperature region and a liquid back state in a low temperature region. This control characteristic is given by having the saturated vapor pressure curve whose inclination is smaller than the saturated vapor pressure curve of the circulating refrigerant R0. The control characteristic EV4 of the expansion valve 331 controls the superheat degree SH to 0 ° C. when the saturation pressure P is about 0.2 MPaG, and the superheat degree SH to 6 ° C. when the saturation pressure P is about 0.3 MPaG. It is set to control. According to this control characteristic, the superheat degree SH is given in the region where the saturation temperature T is higher than about 0 ° C. On the other hand, in a region where the saturation temperature T is lower than about 0 ° C., the superheat degree SH is set to 0 ° C., and a liquid back state in which a large amount of liquid component of the refrigerant R0 is observed occurs. The control characteristic EV4 is set so as to intersect the saturated vapor pressure curve SV0 in the vicinity of the saturation temperature T = 0 in consideration of the use of the refrigeration cycle apparatus 300A for cooling. In the cross charge characteristic, the valve opening is less likely to cause a hunting phenomenon than the normal charge characteristic. This is due to the fact that the cross charge characteristic has a smaller flow rate variation with respect to the temperature variation than the normal charge characteristic.

  In this embodiment, the control characteristic EV4 of the expansion valve 331 is set so as to realize a superheat degree SH that exhibits a high cooling capacity in a normal operation region where a high cooling capacity is required. In cooling applications, the highest cooling performance is required when the evaporation temperature in the evaporator 141 is in the range of 0 ° C. to 10 ° C. This evaporation temperature corresponds to a range of about 0.2 MPaG to 0.3 MPaG at the saturation pressure P. As already described with reference to FIG. 6, by controlling the superheat degree SH within a predetermined range, a high cooling capacity is exhibited. Therefore, in this embodiment, the control characteristic EV4 is set so that the superheat degree SH is controlled within the range of 0 ° C. to 6 ° C. within the range of 0.2 MPaG to 0.3 MPaG as the normal operation region. did.

  According to this embodiment, by providing the internal heat exchanger 160, the refrigerant temperature can be kept low to such an extent that the durability of the components of the refrigeration cycle apparatus 300A is not impaired while sufficiently extracting the refrigeration capacity. As a result, it is possible to improve both the refrigerating capacity and the durability while taking advantage of the circulating refrigerant R0. In addition, the hunting phenomenon of the expansion valve 331 can be suppressed by adopting the cross charge characteristic.

  The lower limit and the upper limit of the degree of superheat SH given by the cross charge characteristic EV4 can be set based on FIG. 6, and may be set to 0 ° C. or more and 5 ° C. or less, for example.

(Other embodiments)
The present invention is not limited to the above-described embodiments, and can be modified or expanded as follows.

  The isentropic line EL0 of the circulating refrigerant R0 can have a slope in the range of 0.044 or more and 0.054 or less. By adopting a refrigerant with an inclination within this range, the rise in the refrigerant temperature during the compression process is suppressed, and even when an internal heat exchanger is provided, the discharge temperature becomes high enough to impair the durability of the parts. Can be prevented.

  The enthalpy width ED0 of the circulating refrigerant R0 can be within a range of −25% to −15% as compared to the enthalpy width EDC of the reference refrigerant R134a. By employing the circulating refrigerant R0 having the enthalpy width ED0 within this range, it is possible to supplement the refrigeration capacity by the internal heat exchanger 160 and obtain a refrigeration capacity that is not significantly different from the reference refrigerant R134a.

  The heat exchange capacity of the internal heat exchanger 160 is such that the increase amount EH of the enthalpy width in the condensation process or evaporation process by the internal heat exchanger 160 is 5% or more with respect to the enthalpy width ED0 of the circulating refrigerant R0 at the saturation temperature 0 ° C. It may be set to be within a range of 10% or less.

  The above-described embodiment can be applied to both an engine-driven compressor and an electric motor-driven compressor. When an electric motor driven compressor is employed, the control characteristics of the expansion valve may be set so as to control the superheat degree SH to a relatively low value in consideration of the heat resistant temperature of the electronic circuit components. desirable.

  Further, the circulating refrigerant R0 may be provided by a single component. Furthermore, the circulating refrigerant R0 can be realized by various mixed refrigerants having different components, component ratios, and the like contained in the mixed refrigerant. Various refrigerants can be used as the low GWP refrigerant included in the circulation refrigerant R0.

  The present invention can also be applied to a refrigeration cycle apparatus including an ejector.

1 is a block diagram showing a first embodiment of a refrigeration cycle apparatus to which the present invention is applied. It is a perspective view which shows the refrigerating-cycle apparatus in 1st Embodiment. It is a block diagram which shows the expansion valve in 1st Embodiment. It is a graph which shows the characteristic of the refrigerant in a 1st embodiment. It is a graph which shows the characteristic of the expansion valve in 1st Embodiment. It is a graph which shows the relationship between the refrigerating capacity and superheat degree in 1st Embodiment. It is a graph which shows the relationship between the refrigerating capacity and discharge temperature in 1st Embodiment. It is a block diagram which shows 2nd Embodiment of the refrigerating-cycle apparatus to which this invention is applied. It is a graph which shows the characteristic of the expansion valve in 2nd Embodiment. It is a block diagram which shows 3rd Embodiment of the refrigerating-cycle apparatus to which this invention is applied. It is a graph which shows the characteristic of the expansion valve in 3rd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100A Refrigeration cycle apparatus 110 Compressor 120 Condenser 131 Expansion valve 141 Evaporator 160 Internal heat exchanger R0 Circulating refrigerant EL0 Isentropic line ED0 Two-phase enthalpy width

Claims (10)

In a refrigeration cycle apparatus including a compressor (110, 210), a condenser (120), an expansion valve (131, 231, 331), and an evaporator (141),
Heat exchange is performed between the high-pressure refrigerant between the condenser (120) and the expansion valves (131, 231, 331) and the low-pressure refrigerant between the evaporator (141) and the compressor (110, 210). An internal heat exchanger (160)
A circulating refrigerant circulating in the refrigeration cycle, the slope of the isentropic line (EL0) on the ph diagram is larger than the isentropic line (ELC) of the refrigerant R134a, and the enthalpy width of the two-phase region on the ph diagram (ED0) is provided with the circulating refrigerant (R0) narrower than the enthalpy width (EDC) of the refrigerant R134a. The enthalpy width (ED0) of the two-phase region of the circulating refrigerant (R0) at a saturation temperature of 0 ° C. on the ph diagram is −15% or less with respect to the enthalpy width (EDC) of the two-phase region of the refrigerant R134a,
The internal heat exchanger (160) has an enthalpy width of the condensation process or evaporation process on the ph diagram, and an enthalpy width (ED0) of the two-phase region of the circulating refrigerant (R0) at a saturation temperature of 0 ° C. on the ph diagram. The refrigeration cycle apparatus according to claim 1, wherein the refrigeration cycle apparatus is set to increase (EH) by 5% or more. The enthalpy width (ED0) of the two-phase region of the circulating refrigerant (R0) at a saturation temperature of 0 ° C on the ph diagram is -25% or more and -15% with respect to the enthalpy width (EDC) of the two-phase region of the refrigerant R134a. Within the following range,
The internal heat exchanger (160) has an enthalpy width of the condensation process or evaporation process on the ph diagram, and an enthalpy width (ED0) of the two-phase region of the circulating refrigerant (R0) at a saturation temperature of 0 ° C. on the ph diagram. The refrigeration cycle apparatus according to claim 2, wherein the refrigeration cycle apparatus is set to increase (EH) within a range of 5% to 10%.   The isentropic line (EL0) of the circulating refrigerant (R0) passing through the intersection of the saturation temperature of 0 ° C and the saturated gas line has an inclination in the range of 0.044 or more and 0.054 or less. Item 4. The refrigeration cycle apparatus according to any one of Items 1 to 3.   The refrigeration cycle apparatus according to any one of claims 1 to 4, wherein the circulating refrigerant (R0) is a mixed refrigerant including at least one low GWP refrigerant. The expansion valve (131, 231)
It has normal charge characteristics (EV1, EV3) set so as to control the superheat degree (SH) of the refrigerant at the outlet of the evaporator (141) to a target value within a range of 0 ° C to 6 ° C. The refrigeration cycle apparatus according to any one of claims 1 to 5, wherein   The refrigeration cycle apparatus according to claim 6, wherein the compressor (210) includes an electric motor (212) and a control circuit (213) mounted to receive heat of the refrigerant. The expansion valve (331)
A cross charge characteristic (EV4) set to control the superheat degree (SH) of the refrigerant at the outlet of the evaporator (141) within a range of 0 ° C. or more and 6 ° C. or less within the range of the normal operation region. The refrigeration cycle apparatus according to claim 1, wherein the refrigeration cycle apparatus is provided. The normal operation region corresponds to a range in which the refrigerant pressure (P) at the outlet of the evaporator (141) is 0.2 MPaG or more and 0.3 MPaG or less,
The cross charge characteristic (EV4) indicates that the superheat degree (SH) of the refrigerant at the outlet of the evaporator (141) when the pressure (P) of the refrigerant at the outlet of the evaporator (141) is 0.3 MPaG. The refrigeration cycle apparatus according to claim 8, wherein the refrigeration cycle apparatus is set to control at 0 ° C.   10. The refrigeration cycle apparatus (100 </ b> A, 200 </ b> A, 300 </ b> A) is used for a vehicle air conditioner, and the internal heat exchanger (160) is a double pipe. Refrigeration cycle equipment.

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