JP2009063230A - Refrigerating cycle device and air conditioning device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress delay in cooling of an evaporator disposed at a downstream side in a refrigerating cycle device constituted by connecting the plurality of evaporators in series. <P>SOLUTION: An upstream-side evaporator 15 for evaporating a refrigerant decompressed and expanded by a pressure control valve 14 and the downstream-side evaporator 16 for evaporating the refrigerant flowing out from the upstream-side evaporator 15 are connected in series, further a bypass passage 18 for guiding the refrigerant from an inlet side of the upstream-side evaporator 15 to an outlet side of the upstream-side evaporator 15 is disposed in a state of bypassing the upstream-side evaporator 15, and an opening/closing valve 19 for opening and closing the bypass passage 18 is forcibly opened only at a standby time T1 in starting a cycle. Thus the liquid-phase refrigerant decompressed and expanded by the pressure control valve 14 can be allowed to directly flow to the downstream-side evaporator 16 in starting the cycle, and the delay in cooling of the downstream-side evaporator 16 can be suppressed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a refrigeration cycle apparatus including a plurality of evaporators and a vehicle air conditioner to which the refrigeration cycle apparatus is applied.

  DESCRIPTION OF RELATED ART Conventionally, the refrigerating-cycle apparatus provided with the some evaporator applied to the vehicle air conditioner is known. For example, in the refrigeration cycle apparatus of Patent Document 1, the first and second evaporators are connected in parallel, the first evaporator is used for air conditioning of the front seat side space in the passenger compartment, and the second evaporator is used in the passenger compartment. Used for air conditioning in the rear seat space.

In the refrigeration cycle apparatus disclosed in Patent Document 1, decompression means for decompressing and expanding the refrigerant flowing into the first and second evaporators is provided independently on the upstream side of the respective evaporators. By changing the opening, the refrigerant is evaporated at different temperature zones in each evaporator.
JP 2007-163074 A

  By the way, in the refrigeration cycle apparatus of Patent Document 1, the first and second evaporators are connected in parallel, and further, an independent pressure reducing means is provided for the first and second evaporators. The configuration becomes complicated. Further, as in Patent Document 1, when the first and second evaporators are used for air conditioning of the front seat side space and the rear seat side space, respectively, the refrigerant is evaporated in the first and second evaporators in greatly different temperature zones. There is little need to make it.

  Accordingly, the present inventors have simplified the cycle configuration and can evaporate the refrigerant in each evaporator at substantially the same temperature range (hereinafter referred to as a study example). Was examined.

  In this examination example, as shown in FIG. 5, since the upstream evaporator 15 and the downstream evaporator 16 are connected in series on the downstream side of one decompression means, the refrigeration cycle of Patent Document 1 is used. The cycle configuration can be simplified for the apparatus. Furthermore, the refrigerant can be evaporated in the upstream evaporator 15 and the downstream evaporator 16 in substantially the same temperature range. In FIG. 5, the same reference numerals are given to the same or equivalent parts as those in the embodiments described later.

  However, when this examination example is actually operated, there is a case where a so-called cooling delay problem occurs in which the temperature decrease start timing of the cooling target space of the downstream evaporator 16 is greatly delayed with respect to the cycle start timing. . Then, when the present inventors investigated the cause, it is because the temperature of the refrigerant | coolant piping connected to the upstream evaporator 15 and the upstream evaporator 15 is high at the time of starting of a refrigerating cycle apparatus. I found out.

  The reason is that if the temperature of the upstream evaporator 15 or the like is high at the time of startup, the liquid phase refrigerant passing through the upstream evaporator 15 or the like immediately after startup evaporates due to the amount of heat of the upstream evaporator 15 or the like itself. Because it will do. Then, until the upstream evaporator 15 itself is cooled, sufficient liquid phase refrigerant cannot be supplied to the downstream evaporator 16, and the downstream evaporator 16 cannot exhibit the refrigerating capacity.

  Furthermore, such a problem of the cooling delay of the downstream evaporator 16 is, for example, a single-mode operating condition in which only the downstream evaporator 16 exhibits the refrigerating capacity (specifically, a blower for the upstream evaporator 15). 15a is stopped, and the start-up under the operating condition in which only the blower 16a for the downstream evaporator 16 is operated) causes a problem that the cooling target space of the downstream evaporator 16 cannot be immediately cooled.

  In view of the above points, an object of the present invention is to suppress a cooling delay of an evaporator disposed on the downstream side in a refrigeration cycle apparatus in which a plurality of evaporators are connected in series.

  In order to achieve the above object, in the present invention, a compressor (11) that compresses and discharges a refrigerant, a radiator (12) that radiates the refrigerant discharged from the compressor (11), and a radiator (12) Outflowed from the decompression means (14) for decompressing and expanding the refrigerant radiated by the refrigerant, the upstream evaporator (15) for evaporating the refrigerant decompressed and expanded by the decompression means (14), and the upstream evaporator (15) The downstream evaporator (16) that evaporates the refrigerant and flows out to the suction side of the compressor (11) and the upstream evaporator (15) are bypassed to evaporate upstream from the upstream evaporator (15) inlet side. A refrigeration cycle apparatus including a bypass passage (18) for introducing refrigerant to the outlet side of the vessel (15) and an on-off valve (19) for opening and closing the bypass passage (18) is a first feature.

  According to this, even when the temperature of the upstream evaporator (15) itself is rising at the start of the cycle, the pressure reducing means (14) opens the on-off valve (19). The liquid refrigerant expanded under reduced pressure can be directly supplied to the downstream evaporator (16). As a result, the cooling delay of the downstream evaporator (16) can be suppressed.

  Further, for example, by opening the on-off valve (19) at the time of starting the single mode in which only the downstream evaporator 16 exhibits the refrigerating capacity, the cooling target space of the downstream evaporator (16) can be immediately cooled. Become.

  Further, the refrigeration cycle apparatus of the first feature further includes an on-off valve control means (20a) for controlling the operation of the on-off valve (19), and the on-off valve control means (20a) is provided in advance from the start of the cycle. The on-off valve (19) may be opened until a predetermined waiting time (T1) has elapsed.

  According to this, since the on-off valve control means (20a) opens the on-off valve (19) until the standby time (T1) has elapsed since the start of the cycle, it is ensured that the downstream evaporator (16). Can suppress the cooling delay.

  By the way, in the refrigeration cycle of the above-mentioned first feature, suppression of the cooling delay of the downstream evaporator (16) is realized by a simple configuration in which the bypass passage (18) and the on-off valve (19) are provided. Therefore, even when the on-off valve (19) is opened, a small amount of refrigerant can be supplied to the upstream evaporator (15).

  Therefore, in the refrigeration cycle apparatus having the first feature described above, the upstream fan (15a) that blows air toward the upstream evaporator (15) and the upstream that controls the operation of the upstream fan (15a). Side blower control means (20b), and the upstream blower control means (20b) may stop the upstream blower (15a) until the standby time (T1) elapses.

  According to this, since the upstream blower control means (20b) stops the upstream blower (15a) until the waiting time (T1) has elapsed since the start of the cycle, the upstream blower control means (20b) is supplied to the upstream evaporator (15). The amount of heat of the upstream evaporator (15) itself can be effectively absorbed by the refrigerant thus formed.

  As a result, the temperature of the upstream evaporator (15) itself can be lowered during the standby time (T1), so when the on-off valve (19) is closed after the standby time (T1) has elapsed, The temperature of the space to be cooled in the upstream evaporator (15) can also be quickly reduced.

  By the way, in this kind of refrigeration cycle apparatus, oil for lubricating the compressor (11) is generally mixed in the refrigerant and circulated in the cycle together with the refrigerant. Therefore, when the refrigerant flow rate decreases, oil stays in the cycle, causing poor lubrication of the compressor (11). Such poor lubrication adversely affects the durable life of the compressor (11).

  Therefore, as described above, when a small amount of refrigerant is supplied to the upstream evaporator (15) when the on-off valve (19) is opened, the oil is put into the upstream evaporator (15). There is a risk of stagnating and causing poor lubrication of the compressor (11).

  Therefore, in the refrigeration cycle apparatus having the first feature described above, the on-off valve control means (20a) intermittently turns on the on-off valve (19) in the operation mode in which the refrigerating capacity is exhibited only by the downstream evaporator (16). It may be made to open and close.

  According to this, even in the operation mode in which the refrigerating capacity is exhibited only by the downstream evaporator (16), the total refrigerant flow circulating in the cycle is intermittently passed through the upstream evaporator (15). Can do. Therefore, oil can be prevented from staying in the upstream evaporator (15).

  In the refrigeration cycle apparatus having the first feature described above, the on-off valve may be a normally open electromagnetic valve (19) that closes when power is supplied. According to this, even if the energization failure or the like to the electromagnetic valve (19) occurs, the on-off valve is surely opened at the time of startup, so that it is possible to reliably suppress the cooling delay of the downstream evaporator (16).

  In the refrigeration cycle apparatus having the first feature described above, carbon dioxide may be employed as the refrigerant. A refrigeration cycle apparatus that uses carbon dioxide as a refrigerant constitutes a supercritical refrigeration cycle in which the high-pressure side refrigerant pressure exceeds the critical pressure of the refrigerant. Get higher.

  Therefore, the density of the low-pressure side refrigerant is also increased, and the pressure loss of the refrigerant on the low-pressure side can be reduced even with a circuit configuration in which the upstream evaporator (15) and the downstream evaporator (16) are connected in series. As a result, the liquid-phase refrigerant can easily flow into the downstream evaporator (16), and the cooling delay can be further suppressed.

  In the present invention, the refrigeration cycle device (10) of the first feature described above is applied to the vehicle, and the upstream evaporator (15) is used for air conditioning of the rear seat side space in the vehicle interior. The downstream evaporator (16) that is used has a second feature of the vehicle air conditioner used for air conditioning of the front seat side space in the passenger compartment. According to this, since the downstream side evaporator (16) is used for air conditioning of the front seat side space in the vehicle interior, it is possible to suppress the cooling delay of the front seat side space where the driver gets on the air.

  Furthermore, since the upstream evaporator (15) is used for air conditioning of the rear seat side space in the vehicle interior, for example, the refrigerant pipe connecting the upstream evaporator (15) and the downstream evaporator (16) becomes long. . That is, since it becomes the structure which the cooling delay of the downstream evaporator (16) mentioned above occurs easily, the cooling delay suppression effect of the refrigerating cycle device (10) of the 1st characteristic can be acquired very effectively.

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim shows the correspondence with the specific means as described in embodiment mentioned later.

  1-4, one embodiment of the present invention will be described. In the present embodiment, the refrigeration cycle apparatus 10 of the present invention is applied to a vehicle air conditioner. FIG. 1 is an overall configuration diagram of a refrigeration cycle apparatus 10 according to the present embodiment.

  The refrigeration cycle apparatus 10 employs carbon dioxide as a refrigerant, and constitutes a supercritical refrigeration cycle in which the high-pressure side refrigerant pressure is equal to or higher than the critical pressure of the refrigerant (supercritical state). Furthermore, oil for lubricating the compressor 11 is mixed in the refrigerant, and this oil circulates in the cycle together with the refrigerant.

  The compressor 11 sucks the refrigerant in the refrigeration cycle apparatus 10 and compresses and discharges the refrigerant until the pressure becomes equal to or higher than the critical pressure. The driving force is transmitted from a vehicle traveling engine (not shown) via a pulley and a belt. And is driven to rotate. In this embodiment, as the compressor 11, a known swash plate type variable displacement compressor that is configured such that the discharge capacity can be continuously changed by a control signal output from an air conditioning controller 20 described later is employed.

  In the swash plate type variable displacement compressor, the refrigerant discharge capacity can be changed by changing the discharge capacity. The discharge capacity is the geometric volume of the working space where the refrigerant is sucked and compressed, that is, the cylinder volume between the top dead center and the bottom dead center of the piston stroke.

  More specifically, the swash plate type variable displacement compressor is formed inside a swash plate chamber (not shown) for introducing an intermediate pressure, and an electromagnetic capacity control valve 11a for adjusting the intermediate pressure to be introduced into the swash plate chamber. And a swash plate (not shown) that displaces an inclination angle in accordance with the pressure in the swash plate chamber.

  When the valve opening (intermediate pressure) of the electromagnetic capacity control valve 11a is changed by a control signal (control current) output from the air conditioning control device 20, the pressure in the swash plate chamber changes and the swash plate tilts. The angle changes. Further, as the inclination angle of the swash plate changes, the piston stroke (discharge capacity) changes. For example, when the pressure in the swash plate chamber is decreased, the inclination angle of the swash plate is increased, and the piston stroke (discharge capacity) can be increased.

  Of course, the refrigerant discharge capacity may be changed by adopting a fixed capacity type compressor as the compressor 11 and changing the operating rate of the compressor by the on / off of the electromagnetic clutch. Further, the refrigerant discharge capacity may be changed by adopting an electric compressor as the compressor 11 and changing the rotation speed of the electric motor.

  An inlet side of the radiator 12 is connected to the discharge side of the compressor 11. The radiator 12 is a heat-dissipating heat exchanger that performs heat exchange between the high-temperature and high-pressure refrigerant discharged from the compressor 11 and the outside air (air outside the passenger compartment) blown by the cooling fan 12a to radiate the high-pressure refrigerant. The cooling fan 12 a is an electric blower whose rotation speed (amount of blown air) is controlled by a control voltage output from the air conditioning control device 20.

  As described above, since the refrigeration cycle apparatus 10 of the present embodiment constitutes a supercritical refrigeration cycle, the refrigerant radiates heat in the supercritical state without being condensed by the radiator 12.

  A high-pressure side refrigerant flow path 13 a of the internal heat exchanger 13 is connected to the outlet side of the radiator 12. The internal heat exchanger 13 exchanges heat between the refrigerant on the outlet side of the radiator 12 that passes through the high-pressure side refrigerant flow path 13a and the refrigerant on the suction side of the compressor 11 that passes through the low-pressure side refrigerant flow path 13b. The refrigerant passing through 13a is cooled.

  Thereby, the enthalpy difference (refrigeration capacity) of the inlet side refrigerant | coolant and outlet side refrigerant | coolant in the upstream evaporator 15 and the downstream evaporator 16 mentioned later can be increased.

  The specific configuration of the internal heat exchanger 13 includes a configuration in which the refrigerant pipes forming the high-pressure side refrigerant flow path 13a and the low-pressure side refrigerant flow path 13b are brazed and heat-exchanged, or a high-pressure side refrigerant flow A double-pipe heat exchanger configuration in which the low-pressure side refrigerant flow path 13b is disposed outside the inner pipe forming the path 13a can be employed.

  A pressure control valve 14 is connected to the outlet side of the high-pressure side refrigerant flow path 13 a of the internal heat exchanger 13. The pressure control valve 14 is a decompression unit of the present embodiment, and decompresses and expands the high-pressure refrigerant that has flowed out of the internal heat exchanger 13, and at the same time opens the valve opening (throttle opening) so that the high-pressure side refrigerant pressure becomes the target high pressure. ) Is adjusted by a mechanical mechanism.

  Specifically, the pressure control valve 14 has a temperature sensing part 14a provided between the radiator 12 outlet side and the high-pressure side refrigerant flow path 13a inlet side of the internal heat exchanger 13, and this temperature sensing part. A pressure corresponding to the temperature of the high-pressure refrigerant on the outlet side of the radiator 12 is generated inside 14 a, and the balance between the internal pressure of the temperature sensing part 14 a and the outlet-side refrigerant pressure of the high-pressure side refrigerant flow path 13 a of the internal heat exchanger 13 The valve opening degree of the pressure control valve 14 is adjusted.

  As a result, the high-pressure side refrigerant pressure is adjusted to a target high pressure determined by the high-pressure side refrigerant temperature on the outlet side of the radiator 12, so that the coefficient of performance (COP) of the cycle approaches the maximum value. A pressure control valve 14 having such a high-pressure control function is known in Japanese Patent Application Laid-Open No. 2000-81157.

  The inlet side of the upstream evaporator 15 is connected to the outlet side of the pressure control valve 14. The upstream evaporator 15 exchanges heat between the low-pressure refrigerant decompressed and expanded by the pressure control valve 14 and the blown air blown from the blower fan 15a to evaporate the low-pressure refrigerant and exert a heat-absorbing effect. It is an exchanger.

  Further, the inlet side of the downstream evaporator 16 is connected to the outlet side of the upstream evaporator 15. That is, the upstream evaporator 15 and the downstream evaporator 16 are connected in series. The downstream evaporator 16 exchanges heat between the low-pressure refrigerant flowing out from the upstream evaporator 15 and the blown air blown from the blower fan 16a, and evaporates the low-pressure refrigerant to exert an endothermic effect. It is.

  The basic configuration of the upstream evaporator 15 and the downstream evaporator 16 is the same, and both are configured by a well-known fin-and-tube heat exchanger. Further, the upstream evaporator 15 and the downstream evaporator 16 are arranged in a case that forms an air passage for the vehicle interior blown air in the indoor air conditioning unit of the vehicle air conditioner.

  The blown air cooled by the upstream evaporator 15 is reheated by a heating means such as a heater core using engine cooling water as a heat source, and the temperature is adjusted and blown out to the rear seat side space in the vehicle interior. The On the other hand, the temperature of the blown air cooled by the downstream evaporator 16 is similarly adjusted and blown out to the front seat side space in the vehicle compartment.

  Therefore, the cooling target space of the upstream evaporator 15 is a rear seat side space in the vehicle interior, and the cooling target space of the downstream evaporator 16 is a front seat side space in the vehicle interior. Note that each of the blower fans 15 a and 16 a is an electric blower in which the rotation speed (the amount of blown air) is controlled by a control voltage output from the air conditioning control device 20.

  An accumulator 17 is connected to the refrigerant outlet side of the downstream evaporator 16. The accumulator 17 is a gas-liquid separator that separates the refrigerant flowing out of the downstream evaporator 16 into a liquid-phase refrigerant and a gas-phase refrigerant and stores excess refrigerant in the cycle. The gas-phase refrigerant outlet of the accumulator 17 is connected to the low-pressure side refrigerant flow path 13b inlet side of the internal heat exchanger 13, and the low-pressure side refrigerant flow path 13b outlet side is connected to the refrigerant suction side of the compressor 11. Has been.

  Further, in the present embodiment, a bypass passage 18 is provided that bypasses the upstream evaporator 15 and guides the refrigerant from the upstream evaporator 15 inlet side to the upstream evaporator 15 outlet side. As the bypass passage 18, a refrigerant pipe is adopted in which the pressure loss when the refrigerant is passed through the bypass passage 18 is sufficiently smaller than the pressure loss when the refrigerant is passed through the upstream evaporator 15. Yes.

  Such adjustment of the pressure loss can be easily realized by adjusting the pipe diameter (passage area) of the bypass passage 18 or adjusting the overall length of the bypass passage 18.

  In addition, an on-off valve 19 that opens and closes the bypass passage 18 is disposed in the bypass passage 18. This on-off valve 19 is an electromagnetic valve that is controlled to open and close by a control voltage output from the air-conditioning control device 20, and is in a closed state when energized when power is supplied, and is open when not energized. Type solenoid valve.

  Further, the opening / closing valve 19 has a valve diameter (refrigerant passage area) at the time of opening that is equal to or larger than the passage area of the bypass passage 18, and does not require pressure loss when the refrigerant passes through the opening / closing valve 19. It is adjusted not to increase.

  Therefore, in a state where the on-off valve 19 is opened (non-energized state), most of the refrigerant that has flowed out of the pressure control valve 14 passes through the bypass passage 18 and is led to the downstream evaporator 16 side. Of the refrigerant that has flowed out of the control valve 14, a small amount of refrigerant is supplied to the upstream evaporator 16. More specifically, in the present embodiment, 90% to 95% of the refrigerant flowing out from the pressure control valve 14 passes through the bypass passage 18.

  Next, an outline of the electric control unit of the present embodiment will be described. The air conditioning control device 20 includes a known microcomputer including a CPU, a ROM, a RAM, and the like and peripheral circuits thereof. The air conditioning control device 20 performs various calculations and processes based on the control program stored in the ROM, and controls the operations of the various electric actuators described above.

  The air-conditioning control device 20 is integrally configured with control means for controlling various electric actuators. In the present embodiment, in particular, the hardware for controlling the operation of the on-off valve 19 in the air-conditioning control device 20 is used. The configuration of the wear and software is the on-off valve control means 20a.

  Further, the configuration for controlling the operation of the blower fan 15a of the upstream evaporator 15 is referred to as an upstream fan control means 20b, and the configuration for controlling the operation of the blower fan 16a of the downstream evaporator 16 is referred to as a downstream blower control means 20c. Of course, you may comprise each said control means 20a-20c by a separate control apparatus.

  To the input side of the air conditioning control device 20, various air conditioning sensor groups and an operation panel 30 disposed in the passenger compartment are connected. The detection signals of the air conditioning sensor groups and various operation switches provided on the operation panel 30 are connected. The operation signal is input.

  As the air conditioning sensor group, the temperature of the heat exchange fins of the downstream evaporator 16 is detected in addition to the sensors for detecting the vehicle environmental conditions such as the outside air temperature Tam, the inside air temperature Tr, and the amount of solar radiation Ts entering the vehicle interior. A downstream-side evaporation temperature sensor 21 is provided. The downstream evaporation temperature sensor 21 is provided to detect the actual refrigerant evaporation temperature Te in the downstream evaporator 16.

  As the operation switch of the operation panel 30, specifically, an air conditioning operation switch 31 that outputs an operation command signal of the vehicle air conditioner, a single mode that performs only air conditioning of the front seat side space, the front seat side space, and the rear seat side space There are provided an operation mode selection switch 32 for selecting a dual mode for performing both air conditioning, a temperature setting switch 33 for setting a target temperature Tset for the front seat side space, and the like.

  The output side of the air conditioning controller 20 is connected to an electromagnetic capacity control valve 11 a of the compressor 11, an electric motor of the cooling fan 12 a and the blower fans 15 a and 16 a, and an electric actuator such as the on-off valve 19. The operation of the device is controlled by the output signal of the air conditioning controller 20.

  Next, the operation of the present embodiment in the above configuration will be described with reference to FIGS. 2 to 4 are flowcharts showing the control processing executed by the air conditioning control device 20. First, when the air conditioning operation switch 31 is turned on (ON) in a state where a vehicle start switch (ignition switch) (not shown) is turned on, the control flow of FIG. 2 starts.

  In step S1, flags, timers, etc. are initialized, and in the next step S2, a vehicle environmental state signal, that is, a detection signal detected by the air conditioning sensor group and an operation signal of the operation panel 30 are read. Next, in step S3, a target blowing temperature TAO of the vehicle cabin blowing air is calculated.

This TAO is calculated by the following formula F1 based on the air conditioning thermal load fluctuation and the set temperature Tset set by the temperature setting switch 33.
TAO = Kset × Tset−Kr × Tr−Kam × Tam−Ks × Ts + C (F1)
In the above formula F1, Tam is the outside air temperature, Tr is the inside air temperature, Ts is the amount of solar radiation entering the vehicle interior, Kset, Kr, Kam, Ks are control gains, and C is a constant for correction.

  In the next step S4, control signals to be output to various electric actuators excluding the on-off valve 19 are determined. Specifically, with respect to a control signal (control current) output to the electromagnetic capacity control valve 11a of the compressor 11, the target refrigerant determined in accordance with the refrigerant evaporation temperature Te and the target outlet temperature TAO in the downstream evaporator 16 It is determined based on the deviation from the evaporation temperature TEO.

  Moreover, about the control signal (control voltage) output to the electric motor of the cooling fan 12a and the ventilation fans 15a and 16a, with reference to the control map previously memorize | stored in the air-conditioning control apparatus 20 based on the target blowing temperature TAO, It determines so that it may become a suitable ventilation volume according to TAO.

  In the present embodiment, when the operation mode selected by the operation mode selection switch 32 is the single mode, the blower fan 15a of the upstream evaporator 15 is stopped, that is, the blown air amount of the blower fan 15a is 0. The control signal is determined so that

  In the next step S5, it is determined whether the operation mode selected by the operation mode selection switch 32 is the dual mode or the single mode. If it is determined in step S5 that the dual mode is selected, the process proceeds to step S6, and dual mode control is executed. On the other hand, when it is determined in step S5 that the single mode is selected, the process proceeds to step S7, and single mode control is executed.

  Details of the dual mode control executed in step S6 will be described with reference to the flowchart of FIG. First, in step S61, the control signal to be output to the on-off valve 19 is closed (energized state), the timer Tm1 is added in step S62, and the process proceeds to step S63.

  In step S63, it is determined whether or not the timer Tm is equal to or greater than a predetermined waiting time T1, and if Tm1 is equal to or greater than T1, the control signal output to the on-off valve 19 is maintained in the closed state. Then, the process proceeds to step S8. On the other hand, if Tm1 is not equal to or greater than T1 in step S63, the process proceeds to step S64, and the control signal output to the on-off valve 19 is changed to the valve open state.

  Furthermore, it progresses to step S65, a control signal is changed so that the ventilation fan 15a of the upstream evaporator 15 is a stop state, ie, the amount of blowing air, becomes 0, and it progresses to step S8. Therefore, if Tm1 is not equal to or greater than T1 in step S63, the control state is set such that the on-off valve 19 is forcibly opened and the operation of the blower fan 15a is stopped.

  In other words, the on-off valve control means 20a of the present embodiment controls the on-off valve 19 until the predetermined waiting time T1 elapses from the start of the cycle even when the dual mode is selected as the operation mode. The control state is set such that the valve is opened and the operation of the blower fan 15a is stopped.

  Here, the standby time T1 will be described. As described above, in the refrigeration cycle apparatus 10, even when the on-off valve 19 is open, a small flow rate of liquid phase refrigerant can be supplied to the upstream evaporator 15. Therefore, even when the temperature of the upstream evaporator 15 itself is high at the start of the cycle, by evaporating the liquid refrigerant supplied to the upstream evaporator 15, the upstream evaporator 15 itself The temperature can be lowered.

  Therefore, in the present embodiment, even when the temperature of the upstream evaporator 15 is the maximum temperature assumed in the installation environment, the upstream evaporator 15 is supplied to the upstream evaporator 15 when the on-off valve 19 is opened. The time during which the upstream evaporator 15 itself can be sufficiently cooled at the refrigerant flow rate is set as the waiting time T1.

  Next, details of the single mode control executed in step S7 will be described with reference to the flowchart of FIG. First, in step S71, the control signal output to the on-off valve 19 is opened (non-energized state), the timer Tm2 is added in step S72, and the process proceeds to step S73.

  In step S73, it is determined whether or not the timer Tm2 is equal to or greater than a predetermined time T2. If Tm2 is not equal to or greater than T2, the control signal output to the on-off valve 19 is maintained in the open state. The process proceeds to step S8. On the other hand, if Tm2 is equal to or greater than T2 in step S73, the process proceeds to step S74, the control signal output to the on-off valve 19 is changed to the closed state, and the process proceeds to step S75.

  In step S75, it is determined whether or not the timer Tm2 is equal to or greater than the total value of T2 and a predetermined time T3. If Tm2 is not equal to or greater than T2 + T3, the control signal output to the on-off valve 19 is closed. The state is maintained and the process proceeds to step S8. In step S75, if the timer Tm2 is equal to or greater than T2 + T3, the process proceeds to step S76, the timer Tm2 is reset, and the process proceeds to step S8.

  Therefore, in the single mode, the control state is determined so that the on-off valve 19 is opened during a predetermined time T2, and then the on-off valve 19 is closed during a predetermined time T3. Is repeated. That is, the on-off valve control means 20a of this embodiment opens and closes the on-off valve 19 intermittently.

  In step S8, control signals are output from the air-conditioning control device 20 to various electric actuators so that the control state determined in steps S4 to S7 is obtained. In the next step S9, the process waits for the control period τ, and when it is determined that the control period τ has elapsed, the process returns to step S2.

  In the refrigeration cycle apparatus 10 of the present embodiment, as described in the above control routine, the on-off valve control means 20a opens the on-off valve 19 when the single mode cycle is started, and further when the dual mode is started. Even if there is, the on-off valve 19 is opened until the waiting time T1 elapses from the start of the cycle.

  Therefore, the liquid-phase refrigerant decompressed and expanded by the pressure control valve 14 can be directly supplied to the downstream evaporator 16 at the time of starting any of the operation modes. As a result, even when the temperature of the upstream evaporator 15 itself is rising, the cooling delay of the downstream evaporator 16 can be reliably suppressed.

  Further, since the upstream side fan control means 20b stops the upstream side fan 15a until the standby time T1 elapses at the time of starting the dual mode, the upstream side evaporator is driven by the liquid phase refrigerant supplied to the upstream side evaporator 15. The heat quantity of 15 itself can be absorbed effectively. Thereby, when the on-off valve 19 is closed after the standby time T <b> 1 elapses, the temperature of the cooling target space of the upstream evaporator 15 can be quickly reduced.

  Furthermore, since the on-off valve control means 20a opens / closes the on-off valve 19 intermittently during single mode operation, oil can be prevented from staying in the upstream evaporator 15. Furthermore, since the on / off valve 19 and a normally open type solenoid valve are used, the on / off valve is surely opened at the start-up even if a failure in energization to the solenoid valve 19 occurs. The cooling delay of the evaporator 16 can be suppressed.

  Furthermore, in the present embodiment, carbon dioxide is used as the refrigerant and the supercritical refrigeration cycle is configured, so that the pressure on the low-pressure side refrigerant is higher than when a normal chlorofluorocarbon refrigerant is used. Accordingly, since the low-pressure side refrigerant density is also increased, the pressure loss of the refrigerant on the low-pressure side can be reduced even with a circuit configuration in which the upstream evaporator 15 and the downstream evaporator 16 are connected in series.

  Thereby, since sufficient refrigerant | coolant flow volume can be supplied to the upstream evaporator 15 and the downstream evaporator 16, a liquid phase refrigerant | coolant can flow in into the downstream evaporator 16 still more, and it can suppress a cooling delay further. .

  Further, in the vehicle air conditioner of the present embodiment, the cooling target space of the downstream evaporator 16 is the front seat side space in the passenger compartment, so that the cooling target space (front seat) on the side where the driver gets on the cooling side is high. The cooling delay of the side space can be suppressed.

  Further, since the space to be cooled of the upstream evaporator 15 is the rear seat side space in the vehicle interior, the refrigerant pipe connecting the pressure control valve 14 and the upstream evaporator 15, and the upstream evaporator 15 and the downstream side The refrigerant pipe connecting the evaporator 16 becomes long, and the downstream evaporator 16 is likely to be delayed in cooling. Therefore, the ability to suppress the cooling delay of the downstream evaporator 16 as in this embodiment is extremely effective when applied to a vehicle air conditioner.

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

  (1) In the above-described embodiment, the downstream evaporation temperature sensor 21 that detects the temperature of the heat exchange fins of the downstream evaporator 16 is used as the downstream evaporation temperature detection means that detects the refrigerant evaporation temperature Te in the downstream evaporator 16. However, the downstream evaporation temperature detecting means is not limited to this.

  For example, a temperature sensor that detects the temperature of the blown air immediately after being blown from the downstream evaporator 16, a temperature sensor that directly detects the refrigerant temperature in the downstream evaporator 16, or a refrigerant pressure in the downstream evaporator 16 is detected. A pressure sensor or the like may be used as the downstream evaporation temperature detection means.

  (2) In the above-described embodiment, the open / close valve 19 is intermittently opened and closed in a pattern in which the valve is opened for a predetermined time T2 and then closed for a predetermined time T3 during single mode operation. However, the opening / closing operation pattern of the opening / closing valve 19 is not limited to this. For example, the opening / closing operation may be performed a plurality of times after opening the valve by T2.

  Further, a physical quantity related to the amount of oil retained in the upstream evaporator 15 is detected, and the on-off valve 19 is closed when the amount of oil retained in the upstream evaporator 15 exceeds a predetermined value. You may do it. As a physical quantity related to the amount of oil staying in the upstream evaporator 15, the pressure loss of the upstream evaporator 15, the passing refrigerant flow rate, and the like can be adopted.

  (3) In the above-described embodiment, an example in which the refrigeration cycle apparatus 10 of the present invention is applied to a vehicle is described, but the application of the present invention is not limited to this. For example, the present invention may be applied to a stationary commercial refrigeration cycle apparatus. At this time, the cooling target space of the downstream evaporator 16 may be set as a cooling target space on the side with a high cooling frequency. Further, the refrigerant is not limited to carbon dioxide, and a chlorofluorocarbon refrigerant or an HC refrigerant may be employed.

  (4) In the above-described embodiment, the radiator 12 is an outdoor heat exchanger that exchanges heat between the refrigerant and the outside air, and the upstream evaporator 15 and the downstream evaporator 16 are indoor heat exchangers. The upstream evaporator 15 and the downstream evaporator 16 are configured as outdoor heat exchangers that absorb heat from a heat source such as outside air, and the radiator 12 is heated by air or water. The present invention may be applied to a heat pump cycle configured as an indoor heat exchanger that heats a fluid.

It is a whole lineblock diagram of the refrigeration cycle device for vehicles of one embodiment. It is a flowchart which shows control of the refrigeration cycle apparatus for vehicles of one Embodiment. It is a flowchart which shows the principal part of control of the refrigeration cycle apparatus for vehicles of one Embodiment. It is a flowchart which shows another principal part of control of the refrigerating-cycle apparatus for vehicles of one Embodiment. It is a whole block diagram of the refrigeration cycle apparatus of the examination example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Compressor, 12 ... Radiator, 14 ... Pressure control valve, 15 ... Upstream evaporator,
15a ... Upstream fan, 16 ... Downstream evaporator, 18 ... Bypass passage, 19 ... Open / close valve,
20a ... Opening / closing valve control means, 20b ... Upstream fan control means.

Claims (7)

A compressor (11) for compressing and discharging the refrigerant;
A radiator (12) for radiating the refrigerant discharged from the compressor (11);
Decompression means (14) for decompressing and expanding the refrigerant radiated by the radiator (12);
An upstream evaporator (15) for evaporating the refrigerant decompressed and expanded by the decompression means (14);
A downstream evaporator (16) that evaporates the refrigerant that has flowed out of the upstream evaporator (15) and flows it out to the suction side of the compressor (11);
A bypass passage (18) that bypasses the upstream evaporator (15) and guides the refrigerant from the inlet side of the upstream evaporator (15) to the outlet side of the upstream evaporator (15);
A refrigerating cycle device comprising: an on-off valve (19) for opening and closing the bypass passage (18). Furthermore, an on-off valve control means (20a) for controlling the operation of the on-off valve (19) is provided,
The refrigeration according to claim 1, wherein the on-off valve control means (20a) opens the on-off valve (19) until a predetermined waiting time (T1) elapses from the start of the cycle. Cycle equipment. Furthermore, an upstream fan (15a) for blowing air toward the upstream evaporator (15),
An upstream fan control means (20b) for controlling the operation of the upstream fan (15a),
The refrigeration cycle apparatus according to claim 2, wherein the upstream blower control means (20b) stops the upstream blower (15a) until the waiting time (T1) has elapsed. The on-off valve control means (20a) opens / closes the on-off valve (19) intermittently in an operation mode in which only the downstream evaporator (16) exhibits a refrigerating capacity. 3. The refrigeration cycle apparatus according to 3. The refrigeration cycle apparatus according to any one of claims 1 to 4, wherein the on-off valve is a normally open electromagnetic valve (19) that closes when power is supplied. The refrigeration cycle apparatus according to any one of claims 1 to 5, wherein carbon dioxide is employed as the refrigerant. A vehicle air conditioner to which the refrigeration cycle apparatus (10) according to any one of claims 1 to 6 is applied,
The upstream evaporator (15) is used for air conditioning of the rear seat side space in the vehicle interior,
The downstream evaporator (16) is used for air conditioning of a front seat side space in a passenger compartment.

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