JP4475243B2 - Air conditioner for vehicles - Google Patents

Description

  The present invention relates to a vehicle air conditioner having a hot gas heating function in which an indoor heat exchanger is used as a radiator of a gas refrigerant by introducing hot gas into the indoor heat exchanger during heating.

The conventional vehicle air conditioner executes control for limiting the temperature of the air blown from the evaporator by limiting the capacity of the hot gas when it is determined that the evaporator has a water retention amount in the heating mode by the hot gas. By this, while ensuring the fogging prevention effect of a window glass, it is an apparatus which exhibits the heating capability of the heating mode by hot gas effectively (for example, refer patent document 1).
JP 2003-159931 A

  However, in the conventional vehicle air conditioner, it is determined that there is no water retention amount when the outside air temperature is relatively high (for example, −10 ° C. to 5 ° C.) and the humidity is high (for example, RH 80% or more). When the hot gas operation is started, a slight amount of condensed water is generated during the cooler operation in the refrigerant recovery operation, and the fogging of the window glass occurs at the subsequent start of the hot gas operation, thereby reducing the visibility of the driver. There was a problem.

  Accordingly, an object of the present invention is to provide an air conditioner for a vehicle that prevents fogging of a window glass at the start of hot gas operation.

  In order to achieve the above object, the following technical means are adopted. That is, according to the first aspect of the vehicle air conditioner, the refrigerant discharged from the compressor (10) passes through the outdoor heat exchanger (14), the cooling decompression device (16), and the indoor heat exchanger (18). By configuring the cycle to return to (10), the refrigeration cycle (30) for operating the indoor heat exchanger (18) as an evaporator, and the refrigerant discharged by the compressor (10) are used as an outdoor heat exchanger. (14) An indoor heat exchanger is configured by forming a cycle that flows into the indoor heat exchanger (18) through the hot gas bypass passage (20) provided so as not to pass through and returns to the compressor (10). The hot gas heater cycle (40) that operates as a radiator (18) and the indoor heat exchanger (18) that is operated by the cooling refrigeration cycle (30) blow out the cooled air into the vehicle interior. And a control means (26) for executing the heating mode by blowing the air heated by the indoor heat exchanger (18) operated by the hot gas heater cycle (40) into the passenger compartment. I have.

  Further, the control means (26) reflects the amount of condensed water generated during the refrigerant recovery operation after the refrigerant recovery operation, which is the heating mode preparation operation by the hot gas heater cycle (40), is finished. The amount of water retained is calculated, and the operation of the compressor (10) is controlled so that the indoor heat exchanger blown air is below the predetermined temperature that does not reach the dew point even if it is cooled by the window glass until it is determined that the amount of retained water has disappeared. It is characterized by that.

  According to the first aspect of the present invention, by calculating the water retention amount that reflects the amount of condensed water generated slightly during the refrigerant recovery operation and controlling the indoor heat exchanger blown air temperature until it is determined that the water retention amount has been lost. Since the influence of the amount of condensed water during the refrigerant recovery operation is eliminated, it is possible to prevent fogging of the window glass that may occur at the start of hot gas operation.

  According to a second aspect, in the first aspect, the control means (26) further determines the maximum amount of condensed water when it is assumed that the air has undergone maximum humidity change before and after the indoor heat exchanger (18) during the refrigerant recovery operation. Is preferably stored in advance, and the amount of condensed water equal to or greater than the maximum amount of condensed water is reflected in the calculation of the water retention amount of the indoor heat exchanger (18) after the refrigerant recovery operation is completed. Note that the data on the maximum amount of condensed water when it is assumed that the humidity has changed to the maximum before and after the indoor heat exchanger (18) during the refrigerant recovery operation is the indoor heat exchanger (18) determined based on experimental data. Assuming a maximum humidity change amount that is difficult to generate exceeding the normal humidity change of the air before and after, the amount of condensed water when this maximum humidity change amount occurs is intended.

  According to the present invention, the control means performs the calculation of the water retention amount based on the condition that the window glass cannot be fogged, so that the window glass is completely clouded at the start of the hot gas operation. it can.

  Further, in the second invention, the control means (26) adds the amount of condensed water equal to or greater than the previously stored maximum condensed water amount to the stored water retention amount stored before the refrigerant recovery operation, so that after the refrigerant recovery operation is completed. It is preferable to calculate the water retention amount. According to the present invention, it is possible to calculate the water retention amount that satisfies the condition that the window glass cannot be fogged without requiring a complicated calculation.

  Furthermore, in any one of the above inventions, a heating solenoid valve (21) capable of controlling the inflow of the refrigerant into the hot gas bypass passage (20) is provided, and the control means (26) is configured such that the indoor heat exchanger blown air is more than a predetermined temperature. When the temperature is too high, it is preferable to execute control to stop the operation of the compressor (10) and open the heating solenoid valve (21). According to the present invention, it is possible to prevent the recovered refrigerant to the hot gas heater cycle after the refrigerant recovery operation from flowing out to the condenser.

  Furthermore, it is preferable that the control means (26) in any one of the above inventions performs the refrigerant recovery operation for a shorter time when the temperature is equal to or higher than the predetermined outside air temperature than when the temperature is lower than the predetermined outside air temperature. According to this invention, since the refrigerant recovery operation time can be shortened, the amount of condensed water generated slightly during the refrigerant recovery operation can be reduced, and the fogging factor of the window glass can be reduced.

  Furthermore, it is preferable that the control means (26) in any one of the above inventions performs the refrigerant recovery operation in a shorter time when the outside air temperature is −10 ° C. or more than when it is less than −10 ° C. According to this invention, since the refrigerant recovery operation time in a temperature range where the outside air temperature is relatively high is shortened, the effect of reducing the amount of condensed water generated during the refrigerant recovery operation can be further enhanced.

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

(First embodiment)
A schematic configuration of a vehicle air conditioner according to a first embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a schematic diagram showing a schematic configuration of a vehicle air conditioner in the present embodiment. The compressor 10 is a device that is driven by a water-cooled vehicle engine 12 via an electromagnetic clutch 11, and is configured by, for example, a fixed capacity swash plate compressor. The discharge side of the compressor 10 is connected to the inlet side of the condenser 14 with a cooling solenoid valve 13 interposed therebetween, and the outlet side of the condenser 14 is connected to a liquid receiver 15 that separates the gas-liquid refrigerant and stores the liquid refrigerant. It is connected. The condenser 14 is an outdoor heat exchanger that is arranged in the vehicle engine room together with the compressor 10 and the like and exchanges heat between the outside air blown by the electric cooling fan 14a and the refrigerant flowing inside.

  The outlet side of the liquid receiver 15 is connected to a temperature type expansion valve 16 which is a cooling decompression device. The outlet side of the temperature type expansion valve 16 is connected to an evaporator 18 via a check valve 17. The outlet side of the evaporator 18 is connected to the suction side of the compressor 10 with an accumulator 19 interposed. The evaporator 18 is an indoor heat exchanger that is disposed in the air conditioning case 22 and exchanges heat between the air blown by the air conditioning fan 23 and the refrigerant flowing inside. The temperature expansion valve 16 adjusts the valve opening degree so that the degree of superheat of the refrigerant at the outlet of the evaporator 18 is maintained at a predetermined value in the cooling mode. The accumulator 19 is configured to separate the gas and liquid of the refrigerant and store the liquid refrigerant, and to suck the gas refrigerant and a small amount of liquid refrigerant near the bottom to the compressor 10 side.

  Thus, from the discharge side of the compressor 10, the compressor 10 passes through the cooling solenoid valve 13, the condenser 14, the liquid receiver 15, the temperature type expansion valve 16, the check valve 17, the evaporator 18, and the accumulator 19. The closed circuit returning to the suction side constitutes a cooling refrigeration cycle 30.

  Further, a hot gas bypass passage 20 that bypasses the condenser 14 and the like is provided in the refrigerant passage between the discharge side of the compressor 10 and the inlet side of the evaporator 18, and a heating electromagnetic valve 21 is provided in the bypass passage 20. A diaphragm 21a is provided in series. The throttle 21a is a heating decompression unit, and can be constituted by a fixed throttle such as an orifice or a capillary tube. Thus, the closed circuit returning from the discharge side of the compressor 10 to the suction side of the compressor 10 via the heating solenoid valve 21, the throttle 21 a, the evaporator 18, and the accumulator 19 causes the heating hot gas heater cycle 40. Constitute.

  Inside the air conditioning case 22, an air passage is formed through which air flows toward the vehicle interior, and air blown by the electric air-conditioning blower fan 23 flows. The air-conditioning blower fan 23 is, for example, a centrifugal blower having a centrifugal fan, and is driven by a blower motor 23a controlled by a blower drive circuit. Note that the air flow rate of the air-conditioning blower fan 23 of the present embodiment can be switched continuously or stepwise by adjusting the blower control voltage applied to the blower motor 23a.

  On the suction side of the air-conditioning blower fan 23, an outside air suction port 70 for sucking outside air (hereinafter referred to as outside air), an inside air suction port 71 for sucking inside air (hereinafter referred to as inside air), and An inside / outside air switching door 72 is provided. The inside / outside air switching door 72 is driven by an actuator such as a servo motor via a link mechanism (not shown) to switch at least between an outside air mode for sucking outside air from the outside air suction port 70 and an inside air mode for sucking inside air from the inside air suction port 71. .

  In the cooling mode, the refrigerant in the cooling refrigeration cycle 30 circulates, and the air blown by the air-conditioning blower fan 23 is cooled by the refrigerant evaporation (heat absorption) in the evaporator 18. In the heating mode, since the high-temperature refrigerant gas (hereinafter referred to as hot gas) from the hot gas bypass passage 20 flows in and heats the air, the evaporator 18 serves as a radiator.

  A drain port 22 a for draining the condensed water generated in the evaporator 18 is provided at a lower portion of the evaporator 18 in the air conditioning case 22. The condensed water is drained out of the passenger compartment through a drain pipe (not shown) connected to the drain port 22a.

  On the downstream side of the evaporator 18 in the air conditioning case 22, a hot water heating heat exchanger 24 that heats blown air using engine cooling water from the vehicle engine 12 as a heat source is disposed. The hot water circuit of the heating heat exchanger 24 and the vehicle engine 12 is provided with a hot water valve 25 that controls the flow of hot water. Incidentally, the heating heat exchanger 24 serves as a main heating means for heating the passenger compartment, whereas the evaporator 18 serving as a radiator by the hot gas heater cycle 40 constitutes an auxiliary heating means. It is.

  Further, on the downstream side of the heating heat exchanger 24 in the air conditioning case 22, a defroster outlet 31 for mainly blowing warm air toward the inner surface of the vehicle front window glass, and mainly toward the upper body of the occupant A face air outlet 32 for blowing out cold air and a foot air outlet 33 for mainly blowing out hot air toward the feet of the occupant are provided. A plurality of mode switching doors 34, 35, and 36 that selectively open and close these air outlets 31, 32, and 33 are rotatably provided. Note that the mode switching doors 34, 35, and 36 constitute blowing mode switching means, and are driven by an actuator such as a servo motor via a link mechanism (not shown).

  An air conditioning electronic control device (hereinafter referred to as an air conditioner ECU) 26, which is a control means, includes a microcomputer and its peripheral circuits, performs predetermined arithmetic processing according to a preset program, and controls the electromagnetic valves 13, 21. Controls the opening and closing and the operation of other electrical equipment (11, 14a, 23, 25, etc.).

  FIG. 2 is a block diagram showing a control configuration of the vehicle air conditioner. As shown in FIG. 2, the air conditioner ECU 26 includes a water temperature sensor 27 a, an outside air temperature sensor 27 b, an evaporator blown air temperature sensor 27 c, a compressor discharge pressure sensor 27 d, an inside air temperature sensor 27 e, A detection signal is input from a sensor group such as a solar sensor 27f that detects the amount of solar radiation.

  In addition, an air conditioner switch 29a, a mode change switch 29b, a temperature setting switch 29c, a hot gas switch 29d, a blower switch 29e, an inside / outside air change switch 29f, and the like are provided by operating the air conditioning operation panel 28 installed in the vicinity of the vehicle interior instrument panel. An operation signal of the operation switch group is input to the air conditioner ECU 26.

  The air conditioner switch 29a is an operation switch for instructing to start or stop the compressor 10, and serves as a cooling switch for setting the cooling mode. The hot gas switch 29d is an operation switch for setting a heating mode by the hot gas heater cycle 40, and serves as a heating switch. The mode switch 29c is an operation switch for switching the air-conditioning blowing mode, and the temperature setting switch 29c is an operation switch for setting the temperature in the passenger compartment to a desired temperature. The blower switch 29e is an operation switch for instructing on / off of the air-conditioning blower fan 23 and air volume switching, and the inside / outside air switching switch 29f is an operation switch for instructing switching between the outside air mode and the inside air mode.

  The operation of the vehicle air conditioner in the above configuration will be described. First, when the air conditioner switch 29a is turned on and the cooling mode is set, the air conditioner ECU 26 opens the cooling electromagnetic valve 13 and controls the heating electromagnetic valve 21 to be closed. When the air conditioner ECU 26 drives the compressor 10 by the vehicle engine 12 with the electromagnetic clutch 11 connected, the discharged gas refrigerant of the compressor 10 passes through the open cooling electromagnetic valve 13 and flows into the condenser 14. It will be. At this time, in the condenser 14, the refrigerant is cooled and condensed by the outside air blown by the cooling fan 14a. The refrigerant after passing through the condenser 14 is gas-liquid separated by the liquid receiver 15, and only the liquid refrigerant is decompressed by the temperature type expansion valve 16 and becomes a low-temperature low-pressure gas-liquid two-phase state.

  Further, the low-pressure refrigerant passes through the check valve 17 and flows into the evaporator 18 to absorb heat from the conditioned air blown by the air-conditioning blower fan 23 and evaporate. The conditioned air cooled by the evaporator 18 blows out into the passenger compartment and cools the passenger compartment. The gas refrigerant evaporated in the evaporator 18 is sucked into the compressor 10 through the accumulator 19 and compressed.

  When the hot gas switch 29b is turned on in the winter and the heating mode by the hot gas heater cycle 40 is set, the air conditioner ECU 26 closes the cooling electromagnetic valve 13 and opens the heating electromagnetic valve 21 to make a hot gas bypass. The passage 20 is opened. At this time, the high-temperature discharged gas refrigerant (superheated gas refrigerant) of the compressor 10 passes through the open heating electromagnetic valve 21 and is depressurized by the throttle 21a, and then flows into the evaporator 18. That is, the superheated gas refrigerant (hot gas) from the compressor 10 bypasses the condenser 14 and the like and is introduced into the evaporator 18. At this time, the check valve 17 prevents the gas refrigerant from the hot gas bypass passage 20 from flowing to the temperature type expansion valve 16 side.

  Therefore, the refrigeration cycle is a hot gas heater that forms a closed circuit that returns from the discharge side of the compressor 10 to the suction side of the compressor 10 via the heating solenoid valve 21, the throttle 21a, the evaporator 18, and the accumulator 19 in this order. It will be driven by cycle 40. And the hot gas after pressure-reducing by the aperture 21a dissipates heat to the blown air in the evaporator 18 and heats the blown air. The hot gas radiated by the evaporator 18 is sucked into the compressor 10 through the accumulator 19 and compressed.

  Note that when the hot water temperature is low, such as immediately after the vehicle engine 12 is started, the air-conditioning blower fan 23 is controlled to warm up so as to start with a low air volume. The blown air heated by the evaporator 18 is further heated in the heating heat exchanger 24 by flowing hot water through the hot water valve 25 to the heating heat exchanger 24. Therefore, the vehicle air conditioner can blow hot air having a higher temperature heated by both the evaporator 18 and the heating heat exchanger 24 into the passenger compartment even when it is cold.

  Next, as shown in FIG. 3, the experimental results (see FIG. 3 (a)) showing the anti-fogging effect in the heating mode (hereinafter referred to as the hot gas heating mode) by the hot gas of the vehicle air conditioner, and the hot gas The control characteristic figure (refer FIG.3 (b)) of the evaporator blowing temperature at the time of heating mode is demonstrated. FIG. 3A plots experimental data under each condition with the vertical axis representing the evaporator blowing temperature Te (° C.) and the horizontal axis representing the window glass temperature Tws (° C.). The window glass temperature Tws is a vehicle windshield temperature on the vehicle interior side.

The black circles in the figure are actual vehicle evaluation values when the window glass starts to fog in the foot mode, and the black squares indicate when the window glass starts to fog in the defroster mode in which air is blown out from the defroster outlet 31 to the inside of the window glass in the vehicle interior. The actual vehicle evaluation value. Here, the foot mode is a blowout mode in which air is blown out mainly from the foot blower outlet 33 to the foot part of the vehicle interior, and a small amount of air is blown out from the defroster blowout port 31 to the inside of the window glass in the vehicle compartment. In both the foot mode and the defroster mode, the air volume is set to a small air volume (Lo) state of about 150 m ³ / h. The relative humidity of the evaporator blowout air is 90%.

  The line A in FIG. 3A is a line of the window glass temperature Tws at which the evaporator blowout air having a relative humidity of 90% reaches the dew point, that is, the clouding limit line, and the upper side of the clouding limit line A is the window glass. It is a cloudy area and the lower side is a clear area. Therefore, when there is a water retention amount of the evaporator, the evaporator outlet temperature Te is always located in the clear area below the clouding limit line A by maintaining the evaporator outlet temperature Te at a temperature equal to or lower than the window glass temperature Tws. In addition, fogging of the window glass can be reliably prevented. In the region where the window glass temperature Tws is lower than around −8 ° C., the evaporation amount of the condensed water in the evaporator 18 decreases even when the hot gas heating mode is executed, so that the cloudiness limit line A is blown out of the evaporator. It moves to the high temperature side with respect to the temperature Te, and the cloudy region becomes narrower.

  FIG. 3B shows the relationship between the evaporator blow-out temperature Te and the window glass temperature Tws when the window glass starts to fog, and the line A is the same as the fogging limit line A in FIG. When the evaporator blowout temperature Te is controlled to be equal to or lower than the glass temperature of the line A with respect to the change in the window glass temperature Tws, the evaporator blowout air does not reach the dew point, thereby preventing the window glass from fogging. be able to. In other words, the evaporator blowout temperature Te on the line A is slightly higher than the window glass temperature Tws. Therefore, if the evaporator blowout temperature Te is controlled to be equal to or lower than the window glass temperature Tws, the fogging of the window glass is reduced. It can prevent more reliably.

  Further, as can be seen from FIGS. 3A and 3B, in the region where the window glass temperature Tws is lower than around −8 ° C., the evaporator blowout temperature Te when the window glass starts to become cloudy corresponds to the window glass temperature Tws. Located on the higher temperature side. Therefore, a value corrected to a higher temperature side than the actual window glass temperature is used as the window glass temperature Tws in steps S130 and S190 in FIG. 6 (see later) showing the control in the hot gas heating mode executed by the vehicle air conditioner. It is preferable.

  Next, the basic concept of the water retention amount calculation in steps S120 and S180 of FIG. 6, which is a determination step for determining the presence or absence of the water retention amount in the evaporator 18, will be described with reference to FIG. Fig.4 (a) has shown the relationship between the change of the operation | movement form of a refrigerating cycle, and the change of the water retention amount of an evaporator accompanying it. When the cooling mode is set during operation of the vehicle engine 12, condensed water is generated by the cooling and dehumidifying action of the evaporator 18. Therefore, the water retention amount of the evaporator 18 is proportional to the operating time of the cooling mode (compressor operating time). Will increase.

  FIG. 4 shows a change in the amount of water retained when the maximum amount of condensed water retained in the evaporator 18 is 250 cc. The evaporator 18 is a laminated evaporator generally used in a vehicle air conditioner, and has a heat exchanger structure in which a flat tube constituted by a laminated plate and a corrugated fin are combined. It is attached to and held. In the example of FIG. 4, the maximum holding amount is 250 cc. Therefore, when the calculated water holding amount reaches the maximum holding amount, the air conditioner ECU 26 does not increase the water holding amount any more and keeps the water holding amount constant. ing.

  The leftmost diagram in FIG. 4B shows a specific example of the amount of condensed water in (1) cooling mode. This amount of condensed water is an amount per unit time (cc / min), and is a value obtained by subtracting the amount of drainage from the drainage port 22a of the air conditioning case 22 from the amount of condensed water generated in the evaporator 18. 4B, the temperature shown on the horizontal axis is the temperature of the evaporator intake air, and% is the relative humidity of the evaporator intake air. When the temperature of the evaporator suction air increases, the absolute humidity of the evaporator suction air increases and the amount of condensed water increases.

4B, Me2 shown on the horizontal axis indicates that the air volume of the air-conditioning blower fan 23 is the second intermediate air volume (about 280 m ³ / h in this embodiment). . The air flow of the air-conditioning blower fan 23 can be manually switched to four stages of low air volume (Lo), first intermediate air volume (Me1), second intermediate air volume (Me2), and large air volume (Hi). The second intermediate air volume (Me2) is the next higher air volume level than the large air volume (Hi).

  4A and 4B, when the vehicle engine 12 is in operation, the compressor 10 is stopped and neither the cooling mode nor the hot gas heating mode is set. It includes both cases when the compressor 10 stops with the stop. Therefore, the time of leaving in the present embodiment is the state where the compressor 10 is stopped.

Here, when left unattended, it includes both when the air-conditioning blower fan 23 is operating and when it is stopped. During operation of the vehicle engine 12, the air-conditioning blower fan 23 is normally in an operating state.
4A, when the air-conditioning blower fan 23 is stopped, the vehicle engine 12 is stopped.

  At this time, since condensed water is drained from the drain port 22a of the air conditioning case 22, the amount of water retained in the evaporator is reduced by the amount of drainage from the drain port 22a. The middle diagram of FIG. 4B schematically shows a phenomenon in which the water retention amount of the evaporator decreases with the passage of the standing time due to the amount of drainage from the drain port 22a when the air-conditioning blower fan 23 is stopped. It is shown schematically.

  When the air-conditioning blower fan 23 is stopped, the state in which the amount of drainage from the drain outlet 22a is large for a predetermined time, for example, one hour after the compressor 10 is stopped, and the water retention amount of the evaporator is rapidly increased. To decrease. After that, it has been found that the amount of drainage decreases to a small amount and the decrease in water retention amount becomes a small amount. When the air blowing fan 23 is set to operate at the time of leaving, the condensed water is pushed out from the evaporator 18 by the wind pressure of the blown air and the amount of drainage increases again. As shown in the latter half of the figure, the water retention amount of the evaporator tends to decrease again.

Subsequently, when the hot gas heating mode is set, the condensed water evaporates in the evaporator 18 due to the heat radiation action of the evaporator 18, so that the water retention amount decreases by the amount of evaporation. Here, since the condensed water is drained from the drain port 22a of the air conditioning case 22 even in the hot gas heating mode,
The amount of evaporation shown in the rightmost diagram of FIG. 4B is a value including the amount of drainage from the drain port 22a. The amount of evaporation in the hot gas heating mode has a relationship that increases as the evaporator blowout air temperature Te increases.

  From the above discussion based on FIG. 4, the water retention amount of the evaporator can be basically calculated by the equation of water retention amount of the evaporator = condensed water amount−evaporation amount−drainage amount when left standing. Here, the amount of drainage at the time of leaving includes both the amount of drainage when the air-conditioning blower fan 23 is operating and when it is stopped.

  Next, in addition to the basic concept of the water retention amount of the evaporator according to FIG. 4, a specific method for calculating the water retention amount of the evaporator 18 will be described using the control routine of FIG. The control routine of FIG. 5 is started by starting the vehicle engine 12 (turning on an ignition switch), and is always in the constant amount of time during the operation of the vehicle engine 12 and after the engine is stopped, for example, 1 hour. Calculation is performed, and the calculated value of the water retention amount is updated at a predetermined time interval, for example, every minute.

  The air conditioner ECU 26 first reads the stored water retention amount (step S300). This stored water retention amount is the evaporator water retention amount that is calculated when a certain time has elapsed after the previous engine stop and stored in the storage means of the air conditioner ECU 26. The storage means is constituted by, for example, a flash memory or RAM, and reads and writes stored data. The storage means is capable of storing and holding information on the water retention amount even after the power supply to the air conditioner ECU 26 is stopped.

  Next, the air conditioner ECU 26 determines whether or not the cooling mode is set (step S310). Specifically, it is determined whether or not the cooling mode is set based on whether or not the air conditioner switch 29a is turned on. When it is determined that the cooling mode is set, the water retention amount in the cooling mode is calculated by the equation of water retention amount = stored water retention amount + condensed water amount (step S320).

  Here, the amount of condensed water in the cooling mode is calculated based on a map (not shown) programmed in advance in the air conditioner ECU 26. The amount of condensed water tends to increase as the absolute humidity of the air sucked into the evaporator increases and as the operation time of the compressor 10 in the cooling mode (electromagnetic clutch ON time) increases. For this reason, the amount of condensed water is calculated using a map reflecting information related to the absolute humidity of the intake air of the evaporator and the operating time of the compressor 10.

  Since the amount of condensed water in the cooling mode is also correlated with the amount of air sucked into the evaporator, in order to improve the accuracy of calculating the amount of condensed water, the amount of condensed water calculated based on a map programmed in advance in the air conditioner ECU 26 is used. Correction that increases in accordance with the increase may be performed.

  If the determination in step S310 is NO, air conditioner ECU 26 determines whether the hot gas heating mode is set (step S330). Specifically, the presence / absence of the hot gas heating mode setting is determined based on whether or not the hot gas switch 29d is turned on. When it is determined that the hot gas heating mode is set, the water retention amount in the hot gas heating mode is calculated by the equation of water retention amount = stored water retention amount-evaporation amount (step S340).

  Here, the evaporation amount in the hot gas heating mode is specifically calculated based on a map as shown in the rightmost diagram of FIG. This map is programmed in advance in the air conditioner ECU 26. When the evaporator outlet temperature Te increases, the relative humidity around the evaporator tends to decrease, and the amount of condensed water evaporated increases. Therefore, the amount of evaporation per unit time (cc / min) has a relationship that increases as the evaporator outlet temperature Te increases, and the map shows that the amount of evaporation rapidly increases in the range where the evaporator outlet temperature Te is -5 ° C or higher. This is a characteristic diagram showing a quadratic curve.

  In addition, the actual use condition of the hot gas heating mode is when the outside air temperature is low, the evaporator blowout temperature Te is not frequently raised to 5 ° C. or more, and safety against fogging of the window glass is ensured. In view of the above, in the range where the evaporator outlet temperature Te is 5 ° C. or higher, the evaporation amount per unit time is maintained at the upper limit value of 8 cc / min.

  When the determination in step S330 is NO, the air conditioner ECU 26 considers that the compressor 10 is not in the cooling mode or the hot gas heating mode, that is, when the compressor 10 is stopped, and the water retention amount at the time of Calculated by the formula of water retention amount = stored water retention amount-drainage amount (step S350). The amount of drainage when left unattended is calculated based on a map programmed in advance in the air conditioner ECU 26. Further, the amount of drainage when left is the amount of condensed water drained from the drain port 22 a to the outside of the air conditioning case 22.

  In some cases, the cooling mode, the hot gas heating mode, and the leaving mode may be switched during operation of the vehicle engine 12. In this case, the stored water retention amount is calculated in the previous mode in steps S320, S340, and S350. The last water retention amount may be used. Further, after executing step S320, S340, or S350, the air conditioner ECU 26 jumps to step S310 and repeats the determination of step S310 again.

  Next, an overall flow of the operation and control of the vehicle air conditioner in the heating mode using the hot gas heater cycle 40 will be described. The control procedure executed by the air conditioner ECU 26 is specifically shown in the flowchart of FIG.

  First, the control flow starts when the vehicle engine 12 is started (ignition switch is turned on), and the air conditioner ECU 26 determines whether or not the hot gas switch 29d of the air conditioning operation panel 28 is turned on (step S100). . The process does not proceed to the next step S120 until it is determined that the hot gas switch 29d is turned on. When determining that the hot gas switch 29d is turned on, that is, when the hot gas heating mode is set, the air conditioner ECU 26 determines whether or not there is a water retention amount of the evaporator 18 (step S120). . The specific method for calculating the water retention amount is as described with reference to FIGS. 4 and 5 described above. The air conditioner ECU 26 closes the cooling electromagnetic valve 13 and opens the heating electromagnetic valve 21 when the hot gas switch 29d is turned on.

  When the amount of water retained in the evaporator 18 is almost zero, even if the evaporator 18 acts as a hot gas radiator, the condensed water does not evaporate in the evaporator 18 and there is no fear of fogging of the window glass. . When the air conditioner ECU 26 determines in step S120 that the water retention amount of the evaporator 18 is substantially 0, the air conditioner ECU 26 energizes the electromagnetic clutch 11 to turn on the electromagnetic clutch 11 (step S150). By this control, the compressor 10 is driven by the vehicle engine 12 via the electromagnetic clutch 11 to be in an operating (ON) state.

  On the other hand, if the air conditioner ECU 26 determines that there is a water retention amount of the evaporator 18 in step S120, it is determined in step 130 whether or not the evaporator blowing air temperature Te is higher than the window glass temperature Tws. Here, the evaporator blowing air temperature Te is a temperature detected by the evaporator blowing temperature sensor 27c, the window glass temperature Tws is the inner surface temperature of the vehicle windshield, the outside air temperature Tam and the air blowing into the vehicle interior ( It is calculated based on the temperature rise due to warm air.

  This window glass temperature Tws is the same temperature as the outside air temperature Tam in the initial state before the start of the air-conditioning operation. After that, when warm air is blown into the vehicle interior by executing the heating mode, The glass temperature Tws rises. Therefore, when the amount of increase in the window glass temperature due to the hot air blowing is ΔTws, the window glass temperature Tws is calculated by the equation Tws = Tam + ΔTws.

  When the evaporator blowout air temperature Te> the window glass temperature Tws, the air conditioner ECU 26 shuts off (OFF) the energization of the electromagnetic clutch 11 and stops (OFF) the compressor 10 (step S140). On the other hand, when the evaporator blowing air temperature Te ≦ the window glass temperature Tws, the electromagnetic clutch 11 is energized to bring the electromagnetic clutch 11 into a connected (ON) state (step S150). By this control, the compressor 10 is driven by the vehicle engine 12 via the electromagnetic clutch 11 to be in an operating (ON) state.

  Here, in order to prevent the window glass from fogging during heating, the outside air mode for introducing outside air having a low absolute humidity is usually selected as the inside and outside air suction mode. When the hot gas heater cycle 40 requires a heating mode operation, low temperature outside air near 0 ° C. is introduced into the evaporator 18 during cold weather. Even if the low temperature outside air has a low absolute humidity, the relative humidity is originally high. In addition to this, when the condensed water evaporates in the evaporator 18, the relative humidity of the evaporator blowing air becomes a high value of about 85% to 90%.

  The evaporator blown air is then heated by the hot water heating heat exchanger 24 to rise in temperature, and then blown out into the passenger compartment. When the blown air comes into contact with the low-temperature window glass and is cooled to a temperature lower than the evaporator blown air temperature Te, the dew point is reached and condensation occurs, and the window glass is fogged.

  In the present embodiment, by controlling the operation of the compressor 10 as in steps S120, S130, and S140 described above, the evaporator blowing air temperature Te can be controlled to a temperature equal to or lower than the window glass temperature Tws. With this control, even if the air blown into the passenger compartment comes into contact with the low-temperature window glass and is cooled to a temperature equivalent to that of the window glass, the relative humidity remains at the value after the evaporator blowing (about 85% to 90%). It only rises. That is, by executing steps S120, S130, and S140, the evaporator blowout air temperature Te is controlled within a range in which the dew point is not reached even when the blowout air into the vehicle compartment is cooled by the window glass. Therefore, even if the condensed water evaporates in the evaporator 18, the fogging of the window glass can be reliably prevented.

  Next, in step S160, the air conditioner ECU 26 executes refrigerant recovery operation control that is a preparatory operation for the heating mode (hot gas operation) by the hot gas heater cycle 40.

  When the outside air temperature is low, the refrigerant and oil in the refrigeration cycle have a property of staying (sleeping) in a cold part in the refrigeration cycle. For example, it is conceivable that the refrigerant and oil are easily exposed to the outside air and fall into the condenser 14 having a large volume. For this reason, the amount of refrigerant and oil in the hot gas heater cycle 40 is smaller than when appropriate, and it is necessary to recover the refrigerant from the condenser 14 and the like before starting the hot gas operation. In the refrigerant recovery operation of the present embodiment, the minimum operation time T1 of the compressor 10 for recovering the refrigerant, and the control for stopping the operation of the compressor 10 after the operation time T1 of the compressor 10 is operated for the operation time T1. Is done.

  The air conditioner ECU 26 calculates the water retention amount of the evaporator 18 after the refrigerant recovery operation in step S160 is completed (step S170). This water retention amount is calculated by the equation of water retention amount = stored water retention amount + condensation water amount during the refrigerant recovery operation. At this time, the air conditioner ECU 26 reads the stored water retention amount stored before the refrigerant recovery operation, and performs an operation of adding the amount of condensed water generated during the refrigerant recovery operation to the stored water retention amount.

  It is considered that the amount of condensed water generated during the refrigerant recovery operation is small and cannot be measured. In this embodiment, the amount of condensed water is calculated based on the map shown in FIG. 7, and this map is stored in advance in the air conditioner ECU 26 as a program. FIG. 7 is a graph showing data on the maximum amount of condensed water when it is assumed that the humidity of the air has changed to the maximum before and after the evaporator 18 based on the experimental results regarding the amount of condensed water generated during the refrigerant recovery operation.

  In the graph shown in FIG. 7, the horizontal axis represents the intake air temperature (° C.) of the evaporator 18 which is the pre-evaporator air temperature, and the vertical axis represents the amount of condensed water (g / min). , The results for each air volume of Hi are plotted. In addition, nine side temperature points are set on the air passage surface of the evaporator 18, and the temperature distribution on the air passage surface is also taken into consideration.

Specifically, the air volume is set to Lo = 100 m ^{3 under} the setting conditions where the refrigerant recovery operation time is 20 sec, the pre-evaporator air humidity is 100%, the rotation speed of the compressor 10 is 2085 rpm, and the post-evaporator air humidity is 85%. / H, M1 = 150m ³ / h, Hi = 305m ³ / h, the evaporator pre-air temperature is -5 ° C, 0 ° C, 5 ° C, that is, 9 results It is plotted on the graph. In addition, from the graph of FIG. 7, three lines are formed in the order of the air volume Lo, M1, and Hi from the bottom. The larger the air volume, the more condensed water, and the higher the intake air temperature, the more condensed water. I can see.

  The air conditioner ECU 26 calculates the amount of condensed water with respect to the intake air temperature and the air volume during the refrigerant recovery operation by using the map in which the correlation between the intake air temperature of the evaporator 18 and the amount of condensed water is obtained for each air volume in this way, and collects the refrigerant. Adopted as the amount of condensed water generated during operation. Actually, the air humidity before and after the evaporator 18 is displaced by about 100% to 90%. Therefore, the numerical value of the post-evaporator air humidity of 85% set in FIG. Will be reflected in the calculation of the water retention amount.

  Next, after calculating the water retention amount, the air conditioner ECU 26 determines whether or not there is a water retention amount (step S180). At first, it is considered that the air conditioner ECU 26 determines that there is a water retention amount of the evaporator 18, and subsequently, in step 190, it is determined whether or not the evaporator blowing air temperature Te is higher than the window glass temperature Tws.

  The determination in step S190 is the same as the determination in step S130 described above. As described with reference to FIG. 3, even if the evaporator blown air is blown to the inner surface of the window glass and cooled by the window glass, the dew point is obtained. It is determined whether or not a predetermined temperature that does not reach is exceeded. In step S190, when the evaporator blowing air temperature is equal to or lower than the window glass temperature, the evaporator blowing air is in a state equal to or lower than a predetermined temperature at which the dew point is not reached even when the evaporator blowing air is cooled by the window glass. This determination is based on the description of line A in FIGS. 3 (a) and 3 (b). That is, in the state included in the region below the line A in FIG. 3, the window glass does not become fogged even when the hot gas operation is started. In other words, it evaporates when a water retention amount exists. When the blower air temperature Te is higher than the temperature Tws of the window glass, it is considered that the window glass becomes clouded when the hot gas operation is started.

  When the air conditioner ECU 26 determines that the evaporator blown air temperature Te is higher than the window glass temperature Tws, the air conditioner ECU 26 cuts off the power supply to the electromagnetic clutch 11 to stop the operation of the compressor 10 and the heating electromagnetic wave. The valve 21 is kept open (ON) (step S200). Then, the process jumps to step S180, and the air conditioner ECU 26 executes again step S180 for making the same determination as in step S120 described above.

  As described above, after the refrigerant recovery operation is completed, the air conditioner ECU 26 calculates the water retention amount reflecting the amount of condensed water generated during the refrigerant recovery operation, and does not start the hot gas operation until it is determined that the water retention amount has disappeared. The operation of the compressor 10 is controlled.

  On the other hand, if the air conditioner ECU 26 determines in step S180 that there is no water retention amount or if the evaporator blown air temperature Te is determined to be lower than the temperature Tws of the window glass, the electromagnetic clutch 11 is energized to electromagnetically The clutch 11 is connected (ON) to start operation of the compressor 10, and the heating solenoid valve 21 is opened (ON) to start hot gas operation (step S210). Then, after starting the hot gas operation in this way, the air conditioner ECU 26 returns to the start and repeats a series of controls.

  Note that the refrigerant recovery operation time in step S170 is the minimum operation time (air conditioner operation time) T1 of the compressor 10 for recovering the refrigerant and the stop for stopping the operation of the compressor 10 after the operation time T1 has elapsed. Time (air conditioner stop time) T2. FIG. 8A is a control characteristic diagram of the air conditioner operation time T1 during the refrigerant recovery operation, and FIG. 8B is a control characteristic diagram of the air conditioner stop time T2.

  As shown in FIG. 8, in the refrigerant recovery operation of step S170, when the air conditioner operation time T1 or the air conditioner stop time T2 is equal to or higher than a predetermined outside air temperature, for example, −10 ° C. It is preferable to control. Specifically, T1 is set to 30 sec when the outside air temperature Tam is less than −20 ° C., linearly shortens with increasing temperature in the range of −20 ° C. to −10 ° C., and reaches 20 sec at −10 ° C. or higher. The set value is fixed. T2 is a set value that is linearly shortened as the temperature rises below -10 ° C, and is fixed at 0 sec above -10 ° C.

  As described above, after the refrigerant recovery operation ends, the air conditioner ECU 26 of the vehicle air conditioner according to the present embodiment calculates the water retention amount reflecting the amount of condensed water generated during the refrigerant recovery operation, and determines that the water retention amount has been lost. The operation of the compressor 10 is controlled so as not to start the hot gas operation. With this control, hot gas operation is not started until the influence of the amount of condensate generated slightly during the cooling operation of the refrigerant recovery operation is eliminated, so the window glass is fogged at the start of hot gas operation and driver visibility is reduced. It can be prevented from decreasing.

  In addition, the air conditioner ECU 26 stores in advance the maximum amount of condensed water (see FIG. 7) when it is assumed that the humidity has changed to the maximum before and after the evaporator 18 during the refrigerant recovery operation, and condenses more than this maximum amount of condensed water. It is preferable to reflect the amount of water in the calculation of the amount of water retained after the end of the refrigerant recovery operation. When this control is employed, the amount of water retention is calculated under the condition that the fogging of the window glass cannot occur, thereby making it possible to completely eliminate the fogging of the window glass at the start of the hot gas operation.

  Further, when the evaporator blown air temperature Te is higher than the window glass temperature Tws, the air conditioner ECU 26 cuts off the energization of the electromagnetic clutch 11 to stop the operation of the compressor 10 and opens the heating electromagnetic valve 21. Control to maintain the state is executed. When this control is adopted, it is possible to prevent the recovered refrigerant to the hot gas heater cycle 40 after the refrigerant recovery operation from flowing out toward the condenser 14.

  Moreover, it is preferable that the air conditioner ECU 26 executes the refrigerant recovery operation for a shorter time when the outside air temperature is −10 ° C. or higher than when it is less than −10 ° C. When this control is adopted, the refrigerant recovery operation time can be shortened, so that the amount of condensed water generated during the refrigerant recovery operation can be reduced, and the fogging factor of the window glass can be reduced.

(Other embodiments)
The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

  For example, the window glass temperature Tws used in the determinations of steps S130 and S190 in FIG. 6 is configured to calculate (estimate) the window glass temperature Tws using an existing sensor signal of the vehicle air conditioner. A dedicated temperature sensor may be installed on the inner surface of the glass and directly detected by the dedicated temperature sensor.

It is the schematic diagram which showed schematic structure of the vehicle air conditioner in 1st Embodiment of this invention. It is the block diagram which showed the control structure in the vehicle air conditioner of 1st Embodiment. (A) is a graph by the experimental result which showed the anti-fogging effect of the evaporator blowing temperature control at the time of the hot gas heating mode in 1st Embodiment, (b) is control of the evaporator blowing temperature at the time of the hot gas heating mode FIG. (A) And (b) is explanatory drawing which shows the view of calculation of the evaporator water retention | holding amount in FIG.6 S120. It is a flowchart which shows the calculation method of the evaporator water retention | holding amount in step S120 of FIG. It is the flowchart which showed the control at the time of the hot gas heating mode which the vehicle air conditioner of 1st Embodiment performs. Based on the experimental results regarding the amount of condensed water generated during the refrigerant recovery operation of the vehicle air conditioner of the first embodiment, the data of the maximum amount of condensed water when assuming that the humidity of the air has changed to the maximum before and after the evaporator is shown. It is a graph. (A) is a control characteristic figure of air-conditioner operation time T1 at the time of refrigerant recovery operation of the air-conditioner for vehicles of a 1st embodiment, and (b) is a control characteristic figure of air-conditioner stop time T2.

Explanation of symbols

10 Compressor 12 Vehicle engine 14 Condenser (Outdoor heat exchanger)
16 Temperature expansion valve (cooling decompression device)
18 Evaporator (indoor heat exchanger)
20 Hot gas bypass passage 21 Heating solenoid valve 26 Air-conditioner ECU (control means)
30 Refrigeration cycle for cooling 40 Hot gas heater cycle

Claims (6)

By configuring a cycle for returning the refrigerant discharged by the compressor (10) to the compressor (10) through the outdoor heat exchanger (14), the cooling decompressor (16), and the indoor heat exchanger (18), A cooling refrigeration cycle (30) for operating the indoor heat exchanger (18) as an evaporator;
The refrigerant discharged from the compressor (10) flows into the indoor heat exchanger (18) through a hot gas bypass passage (20) provided so as not to pass through the outdoor heat exchanger (14). A hot gas heater cycle (40) for operating the indoor heat exchanger (18) as a radiator by configuring a cycle to return to the compressor (10);
The indoor heat exchanger (18) operated by the cooling refrigeration cycle (30) performs a cooling mode by blowing out cooled air into the vehicle interior, and is also operated by the hot gas heater cycle (40). Control means (26) for executing the heating mode by blowing the air heated by the indoor heat exchanger (18) into the passenger compartment,
Further, the control means (26) is configured to reflect the amount of condensed water generated during the refrigerant recovery operation after the refrigerant recovery operation, which is the heating mode preparation operation by the hot gas heater cycle (40), is finished. The compressor is configured to calculate a water retention amount of the cooler (18) and to keep the indoor heat exchanger blown air below a predetermined temperature that does not reach a dew point even when cooled by the window glass until it is determined that the water retention amount is lost. A vehicle air conditioner that controls the operation of (10). The control means (26) stores in advance the maximum amount of condensed water when it is assumed that the humidity of the air has changed to the maximum before and after the indoor heat exchanger (18) during the refrigerant recovery operation,
2. The vehicle air conditioner according to claim 1, wherein a condensed water amount equal to or greater than the maximum condensed water amount is reflected in calculation of a water retention amount of the indoor heat exchanger (18) after completion of the refrigerant recovery operation.   The control means (26) adds the amount of condensed water equal to or greater than the previously stored maximum amount of condensed water to the stored amount of retained water stored before the refrigerant recovery operation, thereby obtaining the amount of water retained after the end of the refrigerant recovery operation. The vehicle air conditioner according to claim 2, wherein the vehicle air conditioner is calculated. A heating solenoid valve (21) capable of controlling the inflow of refrigerant into the hot gas bypass passage (20);
The control means (26) stops the operation of the compressor (10) and opens the heating solenoid valve (21) when the indoor heat exchanger blown air is higher than the predetermined temperature. The vehicle air conditioner according to claim 1, 2 or 3, wherein control to perform is performed.   The control means (26) performs the refrigerant recovery operation for a shorter time when the temperature is equal to or higher than a predetermined outside air temperature than when the temperature is lower than the predetermined outside air temperature. Vehicle air conditioner.   The vehicle air conditioner according to claim 5, wherein the predetermined outside air temperature is -10 ° C.

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