REFRIGERATION CYCLE DEVICE

TECHNICAL FIELD

The present disclosure relates to a refrigeration cycle device including an electric expansion valve.

BACKGROUND

Conventionally, a refrigeration cycle device is provided with an electric expansion valve as a decompression unit that decompresses a refrigerant. In the refrigeration cycle device, a proportional-integral-derivative (PID) control is used to control the operation of the electric expansion valve so that the superheat of an outlet-side refrigerant of an evaporator approaches the target superheat.

SUMMARY

According to an aspect of the present disclosure, a refrigeration cycle device includes a decompression unit configured to decompress a refrigerant, an evaporator configured to evaporate the refrigerant decompressed by the decompression unit, a pressure detector configured to detect an outlet-side pressure of the refrigerant at a refrigerant outlet side of the evaporator, a temperature detector configured to detect an outlet-side temperature of the refrigerant at the refrigerant outlet side of the evaporator, and a controller configured to control an operation of the decompression unit. In the refrigerant cycle device, the controller is configured to obtain a delayed outlet-side temperature by performing a delay process on the outlet-side temperature, and to control the decompression unit by using the outlet-side pressure and the delayed outlet-side temperature.

According to an another aspect of the present disclosure, a refrigeration cycle device includes a branch configured to divide a flow of a refrigerant in a refrigerant cycle into separate streams including first and second streams, a first decompression unit configured to decompress the refrigerant in the first stream flowing out of the branch, a first evaporator that evaporates the refrigerant decompressed by the first decompression unit, a second decompression unit configured to decompress the refrigerant in the second stream flowing out of the branch, a second evaporator that evaporates the refrigerant decompressed by the second decompression unit, a first pressure detector configured to detect a first outlet-side pressure of the refrigerant at a refrigerant outlet side of the first evaporator, a second pressure detector configured to detect a second outlet-side pressure of the refrigerant at a refrigerant outlet side of the second evaporator, a first temperature detector configured to detect a first outlet-side temperature of the refrigerant at the refrigerant outlet side of the first evaporator, a second temperature detector configured to detect a second outlet-side temperature of the refrigerant at the refrigerant outlet side of the second evaporator, and a controller configured to control operations of the first decompression unit and the second decompression unit. In this case, the controller controls the first decompression unit based on the first outlet-side pressure and a first delayed outlet-side temperature, obtained by performing a first delay process on the first outlet-side temperature, and controls the second decompression unit based on the second outlet-side pressure and a second delayed outlet-side temperature, obtained by performing a second delay process on the second outlet-side temperature. In addition, the controller is configured to be capable of setting a degree of delay in the first delay process and a degree of delay in the second delay process to different degrees.

According to a further another aspect of the present disclosure, a refrigeration cycle device includes an evaporator that evaporates a refrigerant, a downstream decompression unit configured to decompress the refrigerant flowing out of the evaporator, a pressure detector configured to detect an outlet-side pressure of the refrigerant at a refrigerant outlet side of the evaporator, a temperature detector configured to detect an outlet-side temperature of the refrigerant at the refrigerant outlet side of the evaporator, and a controller configured to control an operation of the downstream decompression unit. In this case, the controller controls the downstream decompression unit based on the outlet-side pressure and a delayed outlet-side temperature obtained by performing a delay process on the outlet-side temperature.

BRIEF DESCRIPTION OF DRAWINGS

The above object, the other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description with reference to the accompanying drawings. In the drawing:

FIG. 1 is a schematic overall configuration diagram of a refrigeration cycle device according to a first embodiment;

FIG. 2 is a control characteristic diagram used to determine a time constant of the refrigeration cycle device according to the first embodiment;

FIG. 3 is a diagram for explaining a control mode of an electric expansion valve in the refrigeration cycle device according to the first embodiment;

FIG. 4 is a control characteristic diagram for determining a throttle opening of the electric expansion valve in an absolute value control of the refrigeration cycle device according to the first embodiment;

FIG. 5 is a schematic overall configuration diagram of a refrigeration cycle device according to a second embodiment;

FIG. 6 is a schematic overall configuration diagram of a refrigeration cycle device according to a third embodiment;

FIG. 7 is a schematic overall configuration diagram of a refrigeration cycle device according to a fourth embodiment;

FIG. 8 is a schematic overall configuration diagram of a refrigeration cycle device according to a fifth embodiment; and

FIG. 9 is a Mollier chart illustrating a change in a state of a refrigerant in the refrigeration cycle device according to the fifth embodiment.

DESCRIPTION OF EMBODIMENTS

In an example of a refrigeration cycle device, a value obtained by subtracting a temperature of an inlet-side refrigerant of an evaporator from a temperature of an outlet-side refrigerant of the evaporator is set as a superheat of an outlet-side refrigerant of the evaporator.

However, when a value obtained by subtracting the temperature of the inlet-side refrigerant of the evaporator from the temperature of the outlet-side refrigerant of the evaporator is detected as the superheat of the outlet-side refrigerant of the evaporator as in the example of the refrigeration cycle device, an actual superheat of the outlet-side refrigerant may not be detected accurately. For example, when the flow velocity of the refrigerant flowing out of the evaporator increases in accordance with a change in operating condition, particles of liquid-phase refrigerant (hereinafter referred to as droplets) may mix with the actual outlet-side refrigerant, even if the superheat is detected.

For this reason, when the operating condition changes, an appropriate control of a decompression unit of the refrigerant cycle device cannot be achieved, which may result in a decrease in the refrigeration capacity exhibited by the evaporator and liquid compression of the compressor.

In view of the above, an object of the present disclosure is to provide a refrigeration cycle device capable of achieving appropriate control of a decompression unit in accordance with an operating condition.

According to a first aspect of the present disclosure, a refrigeration cycle device includes a decompression unit configured to decompress a refrigerant, an evaporator configured to evaporate the refrigerant decompressed by the decompression unit, a pressure detector configured to detect an outlet-side pressure of the refrigerant at a refrigerant outlet side of the evaporator, a temperature detector configured to detect an outlet-side temperature of the refrigerant at the refrigerant outlet side of the evaporator, and a controller configured to control an operation of the decompression unit.

In the refrigerant cycle device, the controller is configured to obtain a delayed outlet-side temperature by performing a delay process on the outlet-side temperature, and to control the decompression unit by using the outlet-side pressure and the delayed outlet-side temperature.

As described above, the decompression control unit controls the operation of the decompression unit by using at least the outlet-side pressure and the delayed outlet-side temperature. Therefore, by changing the degree of delay in the delay process, the decompression unit can be controlled in accordance with various operating conditions. As a result, the refrigeration cycle device according to the first aspect of the present disclosure achieves appropriate control of the decompression unit in accordance with the operating condition.

According to a second aspect of the present disclosure, a refrigeration cycle device includes a branch configured to divide a flow of a refrigerant in a refrigerant cycle into separate streams including first and second streams, a first decompression unit configured to decompress the refrigerant in the first stream flowing out of the branch, a first evaporator that evaporates the refrigerant decompressed by the first decompression unit, a second decompression unit configured to decompress the refrigerant in the second stream flowing out of the branch, a second evaporator that evaporates the refrigerant decompressed by the second decompression unit, a first pressure detector configured to detect a first outlet-side pressure of the refrigerant at a refrigerant outlet side of the first evaporator, a second pressure detector configured to detect a second outlet-side pressure of the refrigerant at a refrigerant outlet side of the second evaporator, a first temperature detector configured to detect a first outlet-side temperature of the refrigerant at the refrigerant outlet side of the first evaporator, a second temperature detector configured to detect a second outlet-side temperature of the refrigerant at the refrigerant outlet side of the second evaporator, and a controller configured to control operations of the first decompression unit and the second decompression unit. In this case, the controller controls the first decompression unit based on the first outlet-side pressure and a first delayed outlet-side temperature, obtained by performing a first delay process on the first outlet-side temperature, and controls the second decompression unit based on the second outlet-side pressure and a second delayed outlet-side temperature, obtained by performing a second delay process on the second outlet-side temperature. In addition, the controller is configured to be capable of setting a degree of delay in the first delay process and a degree of delay in the second delay process to different degrees.

As described above, by changing the degree of delay in the first delay process and the degree of delay in the second delay process, the first decompression unit and the second decompression unit can be controlled in accordance with various operating conditions. At this time, since the degree of delay in the first delay process and the degree of delay in the second delay process can be set to different degrees, an appropriate control can be achieved for each of the first decompression unit and the second decompression unit.

According to a third aspect of the present disclosure, a refrigeration cycle device includes an evaporator that evaporates a refrigerant, a downstream decompression unit configured to decompress the refrigerant flowing out of the evaporator, a pressure detector configured to detect an outlet-side pressure of the refrigerant at a refrigerant outlet side of the evaporator, a temperature detector configured to detect an outlet-side temperature of the refrigerant at the refrigerant outlet side of the evaporator, and a controller configured to control an operation of the downstream decompression unit. In this case, the controller controls the downstream decompression unit based on the outlet-side pressure and a delayed outlet-side temperature obtained by performing a delay process on the outlet-side temperature.

As described above, by changing the degree of delay in the delay process, the decompression unit can be controlled in accordance with various operating conditions. As a result, the refrigeration cycle device according to the third aspect of the present disclosure achieves appropriate control of the decompression unit in accordance with the operating condition.

In the present embodiments, the outlet-side temperature is not limited to the actual measured value that is a value actually detected by each temperature detector, but includes a processed value obtained by performing processing, such as denoising, to improve the stability of control in the decompression control unit. The same applies to each outlet-side pressure.

Furthermore, a control process equivalent to the delay process may be employed as the denoising process. The degree of delay in the delay process in this case is larger than the degree of delay in the denoising process.

The physical quantity detected by each pressure detector is not limited to each outlet-side pressure and may be a physical quantity correlated with each outlet-side pressure as long as each outlet-side pressure can be detected. The same applies to each temperature detector.

Hereinafter, embodiments will be described with reference to the drawings. In the following embodiments, the same or equivalent portions are denoted by the same reference numerals, and detail description thereof will be omitted.

First Embodiment

A first embodiment of a refrigeration cycle device 1 according to the present disclosure will be described with reference to FIGS. 1 to 4. In the present embodiment, the refrigeration cycle device 1 according to the present disclosure is applied to a vehicle air conditioner. The vehicle air conditioner performs air conditioning in a vehicle interior, which is a space to be air conditioned. The refrigeration cycle device 1 adjusts the temperature of ventilation air supplied to the vehicle interior in a vehicle air conditioner.

As illustrated in FIG. 1, the refrigeration cycle device 1 includes a compressor 11, a condenser 12, a receiver 13, an electric expansion valve 14, an evaporator 15, a control device 20, and the like.

The refrigeration cycle device 1 employs a hydrofluoroolefin (HFO) refrigerant (specifically, R1234yf) as a refrigerant. The refrigeration cycle device 1 constitutes a vapor-compression subcritical refrigeration cycle in which the refrigerant pressure on the high-pressure side does not exceed the critical pressure of the refrigerant. Refrigerant oil for lubricating the compressor 11 is mixed in the refrigerant. The refrigerant oil is a polyethylene glycol (PAG) oil that is compatible with a liquid-phase refrigerant. A part of the refrigerant oil circulates through the refrigeration cycle device 1 together with the refrigerant.

The compressor 11 sucks, compresses, and discharges a refrigerant in the refrigeration cycle device 1. The compressor 11 is an electric compressor in which a fixed volume type compression mechanism having a fixed discharge volume is rotationally driven by an electric motor. The rotation speed (i.e., refrigerant discharge capacity) of the compressor 11 is controlled by a control signal output from the control device 20 to be described later.

The refrigerant inlet side of the condenser 12 is connected to the discharge port of the compressor 11. The condenser 12 is an outside air heat exchange part that exchanges heat between the refrigerant discharged from the compressor 11 and the outside air blown from an outside air blower 12a. The condenser 12 is a condensing part that radiates heat of the refrigerant discharged from the compressor 11 to the outside air to condense the refrigerant.

The outside air blower 12a is an outside air blowing part having a rotation speed (i.e., air blowing capacity) controlled by a control voltage output from the control device 20. The condenser 12 is disposed on the foremost side of the vehicle outside the vehicle interior. Therefore, when the vehicle is traveling, traveling air (i.e., outside air) flowing in through the grille can be directed to the condenser 12.

The inlet side of the receiver 13 is connected to the refrigerant outlet of the condenser 12. The receiver 13 is a gas-liquid separator on the high-pressure side that separates the refrigerant flowing out of condenser 12 into gas and liquid, and allows the liquid-phase refrigerant to flow downstream. The receiver 13 is a liquid reception part that stores the separated liquid-phase refrigerant as an excess refrigerant in the cycle. The receiver 13 may be formed integrally with the condenser 12.

The inlet side of the electric expansion valve 14 is connected to the outlet of the receiver 13. The electric expansion valve 14 is a decompression unit that decompresses the refrigerant flowing out of the receiver 13. The electric expansion valve 14 is an electric variable throttle mechanism including a valve body that changes a throttle opening and an electric actuator that displaces the valve body. As the electric actuator, a stepping motor or a brushless motor can be employed. The operation of the electric expansion valve 14 is controlled by a control signal output from the control device 20.

The refrigerant inlet side of the evaporator 15 is connected to the outlet of the electric expansion valve 14. The evaporator 15 is an inside heat exchange part that exchanges heat between the refrigerant decompressed by the electric expansion valve 14 and the ventilation air blown from an inside blower 15a to the space to be air conditioned. The evaporator 15 is an evaporation unit that evaporates the refrigerant decompressed by the electric expansion valve 14 to exert a heat absorbing action, thereby cooling the ventilation air. The suction port side of the compressor 11 is connected to the refrigerant outlet of the evaporator 15.

The inside blower 15a is an inside blowing part having a rotation speed (i.e., air blowing capacity) controlled by a control voltage output from the control device 20. The evaporator 15 and the inside blower 15a are disposed in a case of an inside air conditioning unit (not illustrated). The inside air conditioning unit is an air distribution device for blowing ventilation air, adjusted to an appropriate temperature for air conditioning in the vehicle interior, to an appropriate location in the vehicle interior. The inside air conditioning unit is disposed in the vehicle interior.

The control device 20 is a controller made of a microcomputer including a central processing unit (CPU), a read-only memory (ROM), a random-access memory (RAM,) and the like, and peripheral circuits thereof. The control device 20 performs various calculations and processing based on a control program stored in the ROM and controls operations of various control target devices connected to the output side. More specifically, the control device 20 controls the operations of the compressor 11, the outside air blower 12a, the electric expansion valve 14, and the inside blower 15a.

A control sensor group is connected to the input side of the control device 20. The sensor group includes an outlet-side pressure sensor 21a, an outlet-side temperature sensor 21b, and the like.

The outlet-side pressure sensor 21a is a pressure detector that detects an outlet-side pressure Pe that is the pressure of the outlet-side refrigerant of the evaporator 15. More specifically, the outlet-side pressure sensor 21a detects the pressure of the refrigerant flowing out of the evaporator 15. The outlet-side temperature sensor 21b is a temperature detector that detects an outlet-side temperature Te that is the temperature of the outlet-side refrigerant of the evaporator 15. More specifically, the outlet-side temperature sensor 21b detects the pipe temperature at the outlet portion of the evaporator 15.

Furthermore, in the control device 20, to improve the stability of the control, a processed value obtained by performing a denoising process on a detected value detected in each detector is employed as the detected value of the air-conditioning control sensor group. For example, as the outlet-side temperature Te, a processed value obtained by performing the denoising process by a moving average method on the detected value, actually detected by the outlet-side temperature sensor 21b, is employed.

An operation panel 22 disposed near an instrument panel in the front of the vehicle interior is connected to the input side of the control device 20. The operation panel 22 is provided with various operation switches that are operated by an occupant. Operation signals from various operation switches are input to the control device 20.

The control device 20 is integrally configured with control units that control the operations of various control target devices connected to the output side. Therefore, a configuration (i.e., hardware and software) for controlling the operation of each control target device constitutes the control unit that controls the operation of each control target device.

For example, in the control device 20, a configuration that controls the operation of the compressor 11 is a compressor control unit 20a. In the control device 20, a configuration that controls the operation of the electric expansion valve 14 is a decompression control unit 20b.

The decompression control unit 20b of the present embodiment can detect the refrigerant state of the outlet-side refrigerant of the evaporator 15 to achieve appropriate control of the electric expansion valve 14. Specifically, the decompression control unit 20b can detect a superheat SH and a delayed superheat SHd of the outlet-side refrigerant of the evaporator 15 as the refrigerant state.

The decompression control unit 20b determines the superheat SH with reference to a control map stored in advance in the control device 20 based on the outlet-side pressure Pe detected by the outlet-side pressure sensor 21a and the outlet-side temperature Te detected by the outlet-side temperature sensor 21b. The control map determines the superheat SH corresponding to the outlet-side pressure Pe and the outlet-side temperature Te based on the physical properties of the refrigerant.

The decompression control unit 20b determines the delayed superheat SHd with reference to the control map based on the outlet-side pressure Pe and a delayed outlet-side temperature Ted obtained by performing a delay process on the outlet-side temperature Te. In the present embodiment, a time constant is used as the delay process. The control map determines the superheat SH corresponding to the outlet-side pressure Pe and the delayed outlet-side temperature Ted based on the physical properties of the refrigerant.

Here, the delayed outlet-side temperature Ted is a value obtained by performing the delay process on the detected outlet-side temperature Te. That is, the denoising process is performed on the detected value actually detected by the outlet-side temperature sensor 21b, and the delay process is further performed. The degree of delay by the delay process is set to be larger than the degree of delay by the denoising process. Therefore, the delayed outlet-side temperature Ted has a value delayed from both the outlet-side pressure Pe and the outlet-side temperature Te.

Furthermore, the decompression control unit 20b can store a superheat variation ΔSH and a delayed superheat variation ΔSHd.

The superheat variation ΔSH is a variation of the superheat SH per predetermined reference time. In the present embodiment, a value obtained by subtracting the previously determined superheat SH from the currently determined superheat SH by the decompression control unit 20b is used as the superheat variation ΔSH. The delayed superheat variation ΔSHd is a variation of the delayed superheat SHd per predetermined reference time. In the present embodiment, a value obtained by subtracting the previously determined delayed superheat SHd from the currently determined delayed superheat SHd by the decompression control unit 20b is used as the delayed superheat variation ΔSHd.

As illustrated in the control characteristic diagram of FIG. 2, the decompression control unit 20b increases the time constant as the superheat SH increases. That is, as the superheat SH increases, the degree of delay in the delay process increases. In FIG. 2, a superheat Sb(° C.) is higher than a superheat Sa(° C.). Furthermore, a superheat Sc(° C.) is higher than the superheat Sb(° C.).

When the superheat SH is equal to or lower than a reference high superheat KSHh, the decompression control unit 20b decreases the time constant as the superheat variation ΔSH decreases. That is, when the superheat SH is equal to or lower than the reference high superheat KSHh, the degree of delay in the delay process is reduced as the superheat variation ΔSH decreases.

In other words, when the superheat SH is equal to or lower than the reference high superheat KSHh and the currently determined superheat SH is lower than the previously determined superheat SH, the decompression control unit 20b reduces the degree of delay in the delay process as the absolute value of the superheat variation ΔSH increases. In the present embodiment, the reference high superheat KSHh is set to 8° C.

Next, the operation of the vehicle air conditioner of the present embodiment with the above configuration will be described. The operation control of the vehicle air conditioner is executed by executing a control program stored in advance in the control device 20. The control program starts when an automatic switch on the operation panel 22, which requires automatic control of the vehicle air conditioner, is turned on while the start switch (so-called ignition switch) of the vehicle system is already on.

The control program reads the detection signal of the air-conditioning control sensor group and the operation signal of the operation panel 22 described above. A target blowing temperature TAO, which is a target temperature of the ventilation air blown into the vehicle interior, is calculated based on the read detection signal and operation signal. Furthermore, the operations of various control target devices in the refrigeration cycle device 1 are controlled based on the detection signal, the operation signal, the target blowing temperature TAO, and the like.

For example, the rotation speed of the compressor 11 is controlled so that the refrigerant evaporation temperature at the evaporator 15 approaches the target evaporation temperature. The target evaporation temperature is determined based on the target blowing temperature TAO with reference to a control map stored in advance in the control device 20. In the control map, the target evaporation temperature is determined to decrease as the target blowing temperature TAO decreases.

The rotation speed of the inside blower 15a is determined based on the target blowing temperature TAO with reference to a control map stored in advance in the control device 20. In the control map, the amount of air blown by the inside blower 15a is determined to be maximized in an extremely low temperature range (maximum cooling range) and an extremely high temperature range (maximum heating range) of the target blowing temperature TAO, and the amount of blown air is determined to be decreased as the temperature approaches the intermediate temperature range.

The throttle opening of the electric expansion valve 14 is controlled so that the superheat SH of the outlet-side refrigerant of the evaporator 15 approaches a predetermined target superheat SHO. In the present embodiment, the target superheat SHO is 10° C. More specifically, in the control program of the present embodiment, the control mode of the electric expansion valve 14 is switched as illustrated in FIG. 3 to appropriately adjust the throttle opening of the electric expansion valve 14.

The control modes of the electric expansion valve 14 of the present embodiment include absolute value control, differential control, and protection control. Each control mode will be described below.

(1) Absolute Value Control

The absolute value control is selected when the superheat SH is equal to or less than a predetermined reference low superheat KSHL or when the absolute value of the superheat variation ΔSH is equal to or greater than a predetermined reference variation KASH. In the present embodiment, the reference low superheat KSHL is set to 1° C.

Here, when the superheat SH is relatively low, the area occupied by the gas-liquid two-phase refrigerant in the evaporator 15 increases, so that there is a high possibility that droplets mix with the outlet-side refrigerant of the evaporator 15 flowing at a relatively high speed. When the absolute value of the superheat variation ΔSH is relatively large, high responsiveness is required to control the opening of the electric expansion valve 14. Therefore, the absolute value control is likely to be selected under an operating condition where the possibility of liquid droplets mixing with the outlet-side refrigerant of the evaporator 15 is high, or where high responsiveness is required to control the opening of the electric expansion valve 14.

In the absolute value control, the target throttle opening of the electric expansion valve 14 is determined with reference to a control map stored in advance in the control device 20 based on a valve opening differential pressure ΔPe at each control cycle. The valve opening differential pressure ΔPe is a value obtained by subtracting the outlet-side pressure Pe from a saturation pressure Ped of the refrigerant at the delayed outlet-side temperature Ted described above. The decompression control unit 20b outputs a control signal to the electric expansion valve 14 to achieve the determined target throttle opening.

In the control map, the throttle opening of the electric expansion valve 14 is determined so that the superheat SH approaches the target superheat SHO. Specifically, as illustrated in the control characteristic diagram of FIG. 4, the throttle opening of the electric expansion valve 14 is determined to be increased as the valve opening differential pressure ΔPe increases. As the throttle opening determined by the control map, a value that has been experimentally or analytically confirmed to make the superheat SH reach the target superheat SHO can be employed.

The throttle opening determined by the control map of the present embodiment is a value that changes substantially in the same manner as a thermal expansion valve. The thermal expansion valve is a decompressor configured by a mechanical mechanism including: a temperature sensing portion with a diaphragm that deforms in accordance with a temperature and pressure of an outlet-side refrigerant of an evaporator, and a valve body portion that is displaced in accordance with the deformation of the diaphragm to change a throttle opening.

(2) Differential Control

The differential control is selected when the superheat SH is higher than a predetermined reference high superheat KSHh and the absolute value of the superheat variation ΔSH is lower than the reference variation KASH.

When the superheat SH is relatively high and the absolute value of the superheat variation ΔSH is relatively small, the operation of the refrigeration cycle device 1 is stable, so that there is a low possibility that droplets mix with the outlet-side refrigerant of the evaporator 15. For this reason, the differential control is likely to be selected under an operating condition where the possibility of liquid droplets mixing with the outlet-side refrigerant of the evaporator 15 is low.

In the differential control, the decompression control unit 20b changes the throttle opening of the electric expansion valve 14 so that the superheat SH approaches the target superheat SHO by a feedback control method using the deviation between the superheat SH and the target superheat SHO, the rate of change in deviation, and the integrated value of the deviation. In other words, in the differential control, the PID control is used to change the throttle opening of the electric expansion valve 14 so that the superheat SH approaches the target superheat SHO.

(3) Protection Control

The protection control is selected when the delayed superheat SHd is higher than a predetermined upper-limit superheat SHMAX.

In the refrigeration cycle device 1, the superheat SH or the delayed superheat SHd during the execution of the absolute value control or the differential control changes within a range substantially lower than the upper-limit superheat SHMAX. That is, the upper-limit superheat SHMAX is the maximum superheat that can be assumed during normal operation when the absolute value control or the differential control is executed. Therefore, the upper-limit superheat SHMAX has a value higher than the reference high superheat KSHh. In the present embodiment, the upper-limit superheat SHMAX is set to 20° C.

Examples of the operating condition under which the delayed superheat SHd is higher than the predetermined upper-limit superheat SHMAX include an operating condition under which air bubbles in the liquid-phase refrigerant are unevenly distributed around the valve body portion of the electric expansion valve 14 to increase the passage resistance of the electric expansion valve 14 at high outside air temperature or the like.

In the protection control, the throttle opening is increased by a predetermined amount at each control cycle to set the delayed superheat SHd to be equal to or less than the upper-limit superheat SHMAX, thereby rapidly shifting to the absolute value control or the differential control.

The control program controls the operations of various control target devices in the refrigeration cycle device 1 as described above. The control routine, including reading the detection signal and operation signal, calculating the target blowing temperature TAO, and controlling various control target devices as described above, is repeated at each predetermined control cycle until the end condition of the control program is satisfied.

Therefore, in the refrigeration cycle device 1, the refrigerant discharged from the compressor 11 flows into the condenser 12 and radiates heat through heat exchange with the outside air. The refrigerant condensed in the condenser 12 flows into the receiver 13 and is separated into gas and liquid. The liquid-phase refrigerant flowing out of the receiver 13 flows into the electric expansion valve 14 and is decompressed. At this time, the throttle opening of the electric expansion valve 14 is controlled so that the superheat SH of the outlet-side refrigerant of the evaporator 15 approaches the target superheat SHO.

The refrigerant decompressed by the electric expansion valve 14 flows into the evaporator 15 and evaporates through heat exchange with the ventilation air. Accordingly, the ventilation air is cooled. The gas-phase refrigerant with a superheat flowing out of the evaporator 15 is sucked into the compressor 11 and compressed again.

In the inside air conditioning unit, the ventilation air cooled by the evaporator 15 is reheated as necessary and blown toward an appropriate location in the vehicle interior. This achieves air conditioning in the vehicle interior.

Furthermore, in the refrigeration cycle device 1 of the present embodiment, since the control mode of the electric expansion valve 14 is switched as described above, the electric expansion valve 14 can be appropriately controlled in accordance with the operating condition.

More specifically, in the refrigeration cycle device 1 of the present embodiment, the decompression control unit 20b controls the operation of the electric expansion valve 14 using at least the outlet-side pressure Pe and the delayed outlet-side temperature Ted. Therefore, by changing the time constant used for the delay process, it is possible to perform control corresponding to various operating conditions. As a result, according to the refrigeration cycle device 1 of the present embodiment, the electric expansion valve 14 can be appropriately controlled in accordance with the operating condition.

For example, when the absolute value control is performed at the time of starting the compressor 11, the decrease in the delayed outlet-side temperature Ted is delayed relative to the decrease in the outlet-side pressure Pe, so that the valve opening differential pressure ΔPe can be set to a higher value than when the outlet-side temperature Te is used. Accordingly, the throttle opening of the electric expansion valve 14 can be increased at the time of the starting the compressor 11. That is, the electric expansion valve 14 can be reliably opened at the time of starting compressor 11.

As described with reference to the control characteristic diagram of FIG. 2, the refrigeration cycle device 1 according to the present embodiment increases the time constant as the superheat SH of the outlet-side refrigerant increases. According to this, the superheat SH of the outlet-side refrigerant decreases, and the time constant can be reduced under an operating condition where droplets are likely to mix with the actual outlet-side refrigerant.

Therefore, during the absolute value control, the delayed outlet-side temperature Ted can be quickly lowered to reduce the valve opening differential pressure ΔPe. That is, under the operating condition where the liquid droplets are likely to mix with the actual outlet-side refrigerant, the throttle opening of the electric expansion valve 14 can be reduced to suppress the liquid compression of the compressor 11.

In the refrigeration cycle device 1 according to the present embodiment, as described with reference to the control characteristic diagram in FIG. 2, when the superheat SH of the outlet-side refrigerant is equal to or lower than the reference high superheat KSHh, the time constant is reduced as the superheat variation ΔSH decreases. According to this, the decrease in the superheat SH increases, and the time constant can be decreased under the operating condition where the droplets are likely to mix with the actual outlet-side refrigerant.

In the refrigeration cycle device 1 according to the present embodiment, when the superheat SH is higher than the reference high superheat KSHh and the absolute value of the superheat variation ΔSH is equal to or less than the reference variation KASH, the control can be switched to the differential control. In other words, the control mode can be switched to the differential control under the operating condition where the possibility of liquid droplets mixing with the outlet-side refrigerant of the evaporator 15 is low.

According to this, the superheat SH can be brought closer to the target superheat SHO with higher accuracy than the absolute value control. Therefore, in the differential control, the refrigerant can exhibit sufficient refrigeration capacity in the evaporator 15 while the temperature distribution of the ventilation air in the evaporator 15 is reduced.

In the refrigeration cycle device 1 of the present embodiment, the protection control can be executed when the delayed superheat SHd is higher than the predetermined upper-limit superheat SHMAX. Accordingly, even when air bubbles in the liquid-phase refrigerant are unevenly distributed around the valve body portion of the electric expansion valve 14, the throttle opening can be increased to allow the air bubbles to flow. As a result, it is possible to rapidly shift to the absolute value control or the differential control to bring the superheat SH close to the target superheat SHO.

The absolute value of the superheat variation ΔSH is often equal to or greater than the reference variation KASH because the protection control is often affected by bubbles in the liquid-phase refrigerant. Therefore, when the delayed superheat SHd becomes equal to or less than the upper-limit superheat SHMAX by executing the protection control, the protection control is often shifted to the absolute value control.

As described above, in the absolute value control, the target throttle opening is determined based on the valve opening differential pressure ΔPe that is determined using the delayed outlet-side temperature Ted. Therefore, the determination of whether to execute the protection control using the delayed superheat SHd, which is determined using the delayed outlet-side temperature Ted, corresponds to continuing the control with the same index (i.e., the delayed outlet-side temperature Ted), and is effective for improving stability when the control mode is switched.

Second Embodiment

In the present embodiment, a refrigeration cycle device 1a will be described. The refrigeration cycle device 1a is applied to a dual-air-conditioner-type vehicle air conditioner. In the dual air-conditioner-type vehicle air conditioner, the ventilation air blown to the front seat side and the ventilation air blown to the rear seat side can be cooled by different evaporators.

Thus, as illustrated in the overall configuration diagram of FIG. 5, the refrigeration cycle device 1a includes a branch 16a, a first electric expansion valve 141, a second electric expansion valve 142, a front-seat evaporator 151, and a rear-seat evaporator 152 in contrast to the refrigeration cycle device 1 described in the first embodiment.

The branch 16a divides the flow of the refrigerant flowing out of the receiver 13. As the branch 16a, a three-way joint formed by joining a plurality of pipes, or a three-way joint formed by providing a plurality of refrigerant passages in a metal block or a resin block can be employed.

The first electric expansion valve 141 is a first decompression unit that decompresses one refrigerant flowing out of the branch 16a. The second electric expansion valve 142 is a second decompression unit that decompresses the other refrigerant flowing out of the branch 16a. The basic configurations of the first electric expansion valve 141 and the second electric expansion valve 142 are similar to those of the electric expansion valve 14 described in the first embodiment.

The front-seat evaporator 151 is a front-seat inside heat exchange part that exchanges heat between the refrigerant decompressed by the first electric expansion valve 141 and ventilation air blown from a front-seat blower 151a to the space to be air conditioned on the front-seat side. The front-seat evaporator 151 is a first evaporator that evaporates the refrigerant decompressed by the first electric expansion valve 141 to exert a heat absorbing action, thereby cooling the ventilation air blown to the space to be air conditioned on the front-seat side.

The rear-seat evaporator 152 is a rear-seat inside heat exchange part that exchanges heat between the refrigerant decompressed by the second electric expansion valve 142 and ventilation air blown from a rear-seat blower 152a to the space to be air conditioned on the rear-seat side. The rear-seat evaporator 152 is a second evaporator that evaporates the refrigerant decompressed by the second electric expansion valve 142 to exert a heat absorbing action, thereby cooling the ventilation air blown to the space to be air conditioned on the rear-seat side.

The basic configurations of the front-seat evaporator 151 and the rear-seat evaporator 152 are similar to those of the evaporator 15 described in the first embodiment. The basic configurations of the front-seat blower 151a and the rear-seat blower 152a are similar to those of the inside blower 15a described in the first embodiment.

One inflow port side of a junction 16b is connected to the refrigerant outlet of the front-seat evaporator 151. The other inflow port side of the junction 16b is connected to the refrigerant outlet of the rear-seat evaporator 152. The suction port side of the compressor 11 is connected to the outflow port of the junction 16b. As the junction 16b, a three-way joint with a configuration similar to the branch 16a can be employed. Therefore, in the refrigeration cycle device 1a, the front-seat evaporator 151 and the rear-seat evaporator 152 are connected in parallel to the refrigerant flow.

The front-seat evaporator 151 and the front-seat blower 151a are disposed in a case of a front-seat inside air conditioning unit (not illustrated). The rear-seat evaporator 152 and the rear-seat blower 152a are disposed in a case of a rear-seat inside air conditioning unit (not illustrated). The front-seat inside air conditioning unit and the rear-seat inside air conditioning unit are air distribution devices similar to the inside air conditioning unit described in the first embodiment.

A first outlet-side pressure sensor 211a, a first outlet-side temperature sensor 211b, a second outlet-side pressure sensor 212a, a second outlet-side temperature sensor 212b are connected as a control sensor group to the input side of the control device 20 according to the present embodiment.

The first outlet-side pressure sensor 211a is a first pressure detector for detecting a first outlet-side pressure Pe1 that is the pressure of the outlet-side refrigerant of the front-seat evaporator 151. The first outlet-side temperature sensor 211b is a first temperature detector for detecting a first outlet-side temperature Te1 that is the temperature of the outlet-side refrigerant of the front-seat evaporator 151.

The second outlet-side pressure sensor 212a is a second pressure detector for detecting a second outlet-side pressure Pe2 that is the pressure of the outlet-side refrigerant of the rear-seat evaporator 152. The second outlet-side temperature sensor 212b is a second temperature detector for detecting a second outlet-side temperature Te2 that is the temperature of the outlet-side refrigerant of the rear-seat evaporator 152.

The decompression control unit 20b of the present embodiment controls the operations of the first electric expansion valve 141 and the second electric expansion valve 142.

As in the first embodiment, the decompression control unit 20b of the present embodiment determines the first superheat SH1 of the outlet-side refrigerant of the front-seat evaporator 151 based on the first outlet-side pressure Pe1 and the first outlet-side temperature Te1. Furthermore, similarly to the first embodiment, the decompression control unit 20b determines a first delayed superheat SHd1 based on the first outlet-side pressure Pe1 and a first delayed outlet-side temperature Ted1 obtained by performing a first delay process on the first outlet-side temperature Te1.

As in the first embodiment, the decompression control unit 20b determines the second superheat SH2 of the outlet-side refrigerant of the rear-seat evaporator 152 based on the second outlet-side pressure Pe2 and the second outlet-side temperature Te2. Furthermore, similarly to the first embodiment, the decompression control unit 20b determines a second delayed superheat SHd2 based on the second outlet-side pressure Pe2 and a second delayed outlet-side temperature Ted2 obtained by performing a second delay process on the second outlet-side temperature Te2.

In addition, the decompression control unit 20b of the present embodiment can set the degree of delay in the first delay process and the degree of delay in the second delay process to different degrees. Other configurations of the refrigeration cycle device 1a are similar to those of the refrigeration cycle device 1 described in the first embodiment.

Next, the operation of the present embodiment in the above configuration will be described. In the control program according to the present embodiment, the throttle opening of the first electric expansion valve 141 is controlled so that the first superheat SH1 of the outlet-side refrigerant of the front-seat evaporator 151 approaches a first target superheat SHO1. Similarly to the first embodiment, the control mode of the first electric expansion valve 141 is switched.

The throttle opening of the second electric expansion valve 142 is controlled so that the second superheat SH2 of the outlet-side refrigerant of the rear-seat evaporator 152 approaches a second target superheat SHO2. Similarly to the first embodiment, the control mode of the second electric expansion valve 142 is switched.

In the refrigeration cycle device 1a, the refrigerant outlet of the front-seat evaporator 151 and the refrigerant outlet of the rear-seat evaporator 152 communicate with each other via the junction 16b. The refrigerant evaporation temperature at the front-seat evaporator 151 is thus substantially equal to the refrigerant evaporation temperature at the rear-seat evaporator 152.

In contrast, by changing the first superheat SH1 of the outlet-side refrigerant of the front-seat evaporator 151 and the second superheat SH2 of the outlet-side refrigerant of the rear-seat evaporator 152, the temperature of the ventilation air blown to the rear-seat side and the temperature of the ventilation air blown to the rear-seat side can be set to different values.

Therefore, the decompression control unit 20b of the present embodiment can set the first target superheat SHO1 and the second target superheat SHO2 to different values in accordance with the operation signal of the operation switch. For example, the target superheat at which the target temperature of the ventilation air decreases can be set to 10° C., and the target superheat at which the target temperature of the ventilation air increases can be set to a value higher than 10° C. The other configurations are similar to those of the first embodiment.

Therefore, in the refrigeration cycle device 1a, the refrigerant discharged from the compressor 11 flows into the condenser 12 and radiates heat through heat exchange with the outside air. The refrigerant condensed in the condenser 12 flows into the receiver 13 and is separated into gas and liquid. The flow of the liquid-phase refrigerant flowing out of the receiver 13 is divided at the branch 16a.

One refrigerant divided at the branch 16a flows into the first electric expansion valve 141 and is decompressed. At this time, the throttle opening of the first electric expansion valve 141 is controlled so that the first superheat SH1 of the outlet-side refrigerant of the front-seat evaporator 151 approaches the first target superheat SHO1.

The refrigerant decompressed by the first electric expansion valve 141 flows into the front-seat evaporator 151 and evaporates through heat exchange with ventilation air blown toward the front-seat side in the vehicle interior. Accordingly, the ventilation air blown toward the front seat is cooled. The gas-phase refrigerant with a superheat flowing out of the front-seat evaporator 151 flows into the first inflow port of the junction 16b.

The other refrigerant divided at the branch 16a flows into the second electric expansion valve 142 and is decompressed. At this time, the throttle opening of the second electric expansion valve 142 is controlled so that the second superheat SH2 of the outlet-side refrigerant of the rear-seat evaporator 152 approaches the second target superheat SHO2.

The refrigerant decompressed by the second electric expansion valve 142 flows into the rear-seat evaporator 152 and evaporates through heat exchange with ventilation air blown toward the rear-seat side in the vehicle interior. Accordingly, the ventilation air blown toward the rear seat is cooled. The gas-phase refrigerant with a superheat flowing out of the rear-seat evaporator 152 flows into the other inflow port of the junction 16b. The gas-phase refrigerant with a superheat merged at the junction 16b is sucked into the compressor 11 and compressed again.

In the front-seat inside air conditioning unit, the ventilation air cooled by the front-seat evaporator 151 is blown toward an appropriate position on the front-seat side in the vehicle interior. Accordingly, air conditioning on the front seat side in the vehicle interior is achieved. In the rear-seat inside air conditioning unit, the ventilation air cooled by the rear-seat evaporator 152 is blown toward the rear-seat side in the vehicle interior. Accordingly, air conditioning on the rear seat side in the vehicle interior is achieved.

Furthermore, the refrigeration cycle device 1a according to the present embodiment switches the control modes of the first electric expansion valve 141 and the second electric expansion valve 142 similarly to the first embodiment. Therefore, similarly to the first embodiment, the first electric expansion valve 141 and the second electric expansion valve 142 can be appropriately controlled in accordance with the operating condition.

At this time, in the refrigeration cycle device 1a, the degree of delay in the first delay process and the degree of delay in the second delay process can be set to different degrees. Therefore, it is possible to appropriately control each of the first electric expansion valve 141 and the second electric expansion valve 142.

In the refrigeration cycle device 1a, the decompression control unit 20b may set the first target superheat SHO1 and the second target superheat SHO2 to different values. For this reason, it is extremely effective that the decompression control unit 20b can set the degree of delay in the first delay process and the degree of delay in the second delay process to different degrees to cause each of the front-seat evaporator 151 and the rear-seat evaporator 152 to exhibit an appropriate cooling capacity.

In the present embodiment, the operation of the first electric expansion valve 141 is controlled using the first delayed outlet-side temperature Ted1, and the operation of the second electric expansion valve 142 is controlled using the second delayed outlet-side temperature Ted2. However, the present invention is not limited thereto.

For example, the operation of the first electric expansion valve 141 may be controlled using the first delayed outlet-side temperature Ted1, and the operation of the second electric expansion valve 142 may be controlled without using the second delayed outlet-side temperature Ted2.

In this case, the first electric expansion valve 141 corresponds to the decompression unit described in the first embodiment, and the front-seat evaporator 151 corresponds to the evaporator described in the first embodiment. Furthermore, the first outlet-side pressure sensor 211a corresponds to the pressure detector described in the first embodiment, and the first outlet-side temperature sensor 211b corresponds to the pressure detector described in the first embodiment.

The operation of the second electric expansion valve 142 may be controlled using the second delayed outlet-side temperature Ted2, and the operation of the first electric expansion valve 141 may be controlled without using the first delayed outlet-side temperature Ted1.

In this case, the second electric expansion valve 142 corresponds to the decompression unit described in the first embodiment, and the rear-seat evaporator 152 corresponds to the evaporator described in the first embodiment. Furthermore, the second outlet-side pressure sensor 212a corresponds to the pressure detector described in the first embodiment, and the second outlet-side temperature sensor 212b corresponds to the pressure detector described in the first embodiment.

Third Embodiment

In the present embodiment, a refrigeration cycle device 1b will be described. The refrigeration cycle device 1b is applied to a vehicle air conditioner. The refrigeration cycle device 1b constitutes an internal heat exchange-type gas injection cycle.

Therefore, as illustrated in the overall configuration diagram of FIG. 6, the refrigeration cycle device 1b includes a branch 16a, a first electric expansion valve 141, and a second electric expansion valve 142, similar to those of the second embodiment, along with a compressor 111 and an internal heat exchanger 17, in contrast to the refrigeration cycle device 1 described in the first embodiment.

The compressor 111 is a two-stage boost type electric compressor in which a low-stage side compression mechanism with fixed discharge volume and a high-stage side compression mechanism are driven by a common electric motor. The rotation speed (i.e., refrigerant discharge capacity) of the compressor 111 is controlled by a control signal output from the control device 20.

The compressor 111 includes a housing that houses a low-stage side compression mechanism, a high-stage side compression mechanism, an electric motor, and the like. A low-pressure suction port, an intermediate-pressure suction port, and a discharge port are formed in the housing.

The low-pressure suction port is an opening hole for sucking low-pressure refrigerant from the outside of the housing to the low-stage side compression mechanism. The intermediate-pressure suction port is an opening hole for allowing intermediate-pressure refrigerant to flow from the outside to the inside of the housing to join the refrigerant in a compression process from low to high pressure. Inside the housing, the intermediate-pressure suction port is connected to both the discharge port side of the low-stage side compression mechanism and the suction port side of the high-stage side compression mechanism. The discharge port is an opening hole for discharging high-pressure refrigerant discharged from the high-stage side compression mechanism to the outside of the housing. The refrigerant inlet side of the condenser 12 is connected to the discharge port.

The first electric expansion valve 141 is a first decompression unit that decompresses one refrigerant flowing out of the branch 16a. The inlet side of the intermediate-pressure passage of the internal heat exchanger 17 is connected to the outlet of the first electric expansion valve 141. The inlet side of the high-pressure passage of the internal heat exchanger 17 is connected to the other outflow port of the branch 16a.

The internal heat exchanger 17 is an internal heat exchange part that exchanges heat between the intermediate-pressure refrigerant circulating through the intermediate-pressure passage and the high-pressure refrigerant circulating through the high-pressure passage. The intermediate-pressure passage is a refrigerant passage through which the intermediate-pressure refrigerant decompressed by the first electric expansion valve 141 is circulated. The high-pressure passage is a refrigerant passage through which the other refrigerant flowing out of the branch 16a is circulated.

Therefore, the internal heat exchanger 17 exchanges heat between the intermediate-pressure refrigerant decompressed by the first electric expansion valve 141 and the other refrigerant flowing out of the branch 16a. The internal heat exchanger 17 according to the present embodiment is used as a first evaporator that causes the intermediate-pressure refrigerant to absorb heat from the high-pressure refrigerant, thereby evaporating the intermediate-pressure refrigerant.

The intermediate-pressure suction port of the compressor 111 is connected to the outlet of the intermediate-pressure passage of the internal heat exchanger 17. The inlet side of the second electric expansion valve 142 is connected to the outlet of the high-pressure passage of the internal heat exchanger 17. Thus, the second electric expansion valve 142 of the present embodiment is a second decompression unit that decompresses the other refrigerant flowing out of the branch 16a.

The refrigerant inlet side of the evaporator 15 is connected to the outlet of the second electric expansion valve 142. Thus, the evaporator 15 of the present embodiment corresponds to a second evaporator that evaporates the refrigerant decompressed by the second electric expansion valve 142. The low-pressure suction port side of the compressor 111 is connected to the refrigerant outlet of the evaporator 15. Therefore, in the refrigeration cycle device 1b, the internal heat exchanger 17 and the evaporator 15 are connected in parallel to the refrigerant flow.

The first outlet-side pressure sensor 211a is a first pressure detector for detecting a first outlet-side pressure Pe1 that is the pressure of the outlet-side refrigerant of the intermediate-pressure passage of the internal heat exchanger 17. The first outlet-side temperature sensor 211b is a first temperature detector for detecting a first outlet-side temperature Te1 that is the temperature of the outlet-side refrigerant of the intermediate-pressure passage of the internal heat exchanger 17.

The second outlet-side pressure sensor 212a is a second pressure detector for detecting a second outlet-side pressure Pe2 that is the pressure of the outlet-side refrigerant of the evaporator 15. The second outlet-side temperature sensor 212b is a second temperature detector for detecting a second outlet-side temperature Te2 that is the temperature of the outlet-side refrigerant of the evaporator 15.

The decompression control unit 20b of the present embodiment controls the operations of the first electric expansion valve 141 and the second electric expansion valve 142.

As in the second embodiment, the decompression control unit 20b of the present embodiment determines the first superheat SH1, the first delayed superheat SHd1, the second superheat SH2, and the second delayed superheat SHd2. The decompression control unit 20b can set the degree of delay in the first delay process and the degree of delay in the second delay process to different degrees. Other configurations of the refrigeration cycle device 1b are similar to those of the refrigeration cycle device 1 described in the first embodiment.

Next, the operation of the present embodiment in the above configuration will be described. In the control program of the present embodiment, the throttle opening of the first electric expansion valve 141 is controlled so that the first superheat SH1 of the outlet-side refrigerant of the intermediate-pressure passage of the internal heat exchanger 17 approaches the first target superheat SHO1. Similarly to the first embodiment, the control mode of the first electric expansion valve 141 is switched.

The throttle opening of the second electric expansion valve 142 is controlled so that the second superheat SH2 of the outlet-side refrigerant of the evaporator 15, which is the second evaporator, approaches the second target superheat SHO2. Similarly to the first embodiment, the control mode of the second electric expansion valve 142 is switched.

In the decompression control unit 20b of the present embodiment, the first target superheat SHO1 and the second target superheat SHO2 can be set to different values as in the second embodiment. The other configurations are similar to those of the first embodiment.

Therefore, in the refrigeration cycle device 1b, the refrigerant discharged from the discharge port of the compressor 111 flows into the condenser 12 and radiates heat through heat exchange with the outside air. The refrigerant condensed in the condenser 12 flows into the receiver 13 and is separated into gas and liquid. The flow of the liquid-phase refrigerant flowing out of the receiver 13 is divided at the branch 16a.

One refrigerant divided at the branch 16a flows into the first electric expansion valve 141 and is decompressed. At this time, the throttle opening of the first electric expansion valve 141 is controlled so that the first superheat SH1 of the outlet-side refrigerant of the intermediate-pressure passage of the internal heat exchanger 17 approaches the first target superheat SHO1.

The refrigerant decompressed by the first electric expansion valve 141 flows into the intermediate-pressure passage of the internal heat exchanger 17 and exchanges heat with the high-pressure refrigerant circulating through the high-pressure passage. As a result, the intermediate-pressure refrigerant circulating through the intermediate-pressure passage evaporates, and the high-pressure refrigerant circulating through the high-pressure passage decreases in enthalpy. The gas-phase refrigerant with a superheat flowing out of the intermediate-pressure passage of the internal heat exchanger 17 is sucked into the intermediate-pressure suction port of the compressor 111 and compressed again.

The refrigerant flowing out of the high-pressure passage of the internal heat exchanger 17 flows into the second electric expansion valve 142 and is decompressed. At this time, the throttle opening of the second electric expansion valve 142 is controlled so that the second superheat SH2 of the outlet-side refrigerant of the evaporator 15 approaches the second target superheat SHO2.

The refrigerant decompressed by the second electric expansion valve 142 flows into the evaporator 15 and evaporates through heat exchange with the ventilation air. Accordingly, the ventilation air is cooled. The gas-phase refrigerant with a superheat flowing out of the evaporator 15 is sucked from the low-pressure suction port of the compressor 111 and compressed again.

In the inside air conditioning unit, as in the first embodiment, the ventilation air cooled by the evaporator 15 is blown toward an appropriate location in the vehicle interior. This achieves air conditioning in the vehicle interior. In addition, since the refrigeration cycle device 1b of the present embodiment constitutes the internal heat exchange-type gas injection cycle, the coefficient of performance (COP) of the cycle can be improved.

Furthermore, in the refrigeration cycle device 1b of the present embodiment, the control modes of the first electric expansion valve 141 and the second electric expansion valve 142 are switched as in the first embodiment. Therefore, similarly to the first embodiment, the first electric expansion valve 141 and the second electric expansion valve 142 can be appropriately controlled in accordance with the operating condition.

At this time, in the refrigeration cycle device 1b, similarly to the second embodiment, the degree of delay in the first delay process and the degree of delay in the second delay process can be set to different degrees. Therefore, it is possible to appropriately control each of the first electric expansion valve 141 and the second electric expansion valve 142.

For example, as described in the second embodiment, the operation of the first electric expansion valve 141 may be controlled using the first delayed outlet-side temperature Ted1, and the operation of the second electric expansion valve 142 may be controlled without using the second delayed outlet-side temperature Ted2.

In this case, the first electric expansion valve 141 corresponds to the decompression unit described in the first embodiment, and the internal heat exchanger 17 corresponds to the evaporator described in the first embodiment. Furthermore, the first outlet-side pressure sensor 211a corresponds to the pressure detector described in the first embodiment, and the first outlet-side temperature sensor 211b corresponds to the pressure detector described in the first embodiment.

In this case, the second electric expansion valve 142 corresponds to the decompression unit described in the first embodiment, and the evaporator 15 corresponds to the evaporator described in the first embodiment. Furthermore, the second outlet-side pressure sensor 212a corresponds to the pressure detector described in the first embodiment, and the second outlet-side temperature sensor 212b corresponds to the pressure detector described in the first embodiment.

Fourth Embodiment

In the present embodiment, a refrigeration cycle device 1c will be described. The refrigeration cycle device 1c is applied to a vehicle air conditioner. The refrigeration cycle device 1c constitutes a gas-liquid separation type gas injection cycle.

Therefore, as illustrated in the overall configuration diagram of FIG. 7, the refrigeration cycle device 1c includes a compressor 111, a first electric expansion valve 141, and a second electric expansion valve 142, similar to the third embodiment, along with an intermediate-pressure receiver 13a, in contrast to the refrigeration cycle device 1 described in the first embodiment.

In the refrigeration cycle device 1c, the inlet side of the first electric expansion valve 141 similar to that of the second embodiment is connected to the refrigerant outlet of the condenser 12. The inlet side of the intermediate-pressure receiver 13a is connected to the outlet of the first electric expansion valve 141.

The intermediate-pressure receiver 13a is an intermediate-pressure-side gas-liquid separator that separates the intermediate-pressure refrigerant decompressed by the first electric expansion valve 141 into gas and liquid. The intermediate-pressure receiver 13a is an intermediate-pressure-side liquid reception part that stores the separated liquid-phase refrigerant as an excess refrigerant in the cycle. The intermediate-pressure receiver 13a includes a gas-phase refrigerant outflow port through which the separated gas-phase refrigerant flows out, and a liquid-phase refrigerant outflow port through which the separated liquid-phase refrigerant flows out.

The intermediate-pressure suction port side of the compressor 111 is connected to the gas-phase refrigerant outflow port of the intermediate-pressure receiver 13a. The inlet side of the second electric expansion valve 142 is connected to the liquid-phase refrigerant outflow port of the intermediate-pressure receiver 13a. The second electric expansion valve 142 of the present embodiment is a decompression unit that decompresses the liquid-phase refrigerant flowing out of the intermediate-pressure receiver 13a.

The refrigerant inlet side of the evaporator 15 is connected to the outlet of the second electric expansion valve 142. Therefore, the evaporator 15 of the present embodiment is an evaporator that evaporates the refrigerant decompressed by the second electric expansion valve 142. The low-pressure suction port side of the compressor 111 is connected to the refrigerant outlet of the evaporator 15.

A condenser outlet pressure sensor 213a and a condenser outlet temperature sensor 213b are connected as a control sensor group to the input side of the control device 20 according to the present embodiment. The condenser outlet pressure sensor 213a is a high-pressure detector that detects a high pressure P1 of the refrigerant flowing out of the condenser 12. The condenser outlet temperature sensor 213b is a high-pressure temperature detector that detects a high-pressure temperature T1 of the refrigerant flowing out of the condenser 12. The other configuration of the refrigeration cycle device 1c is similar to that of the refrigeration cycle device 1 described in the first embodiment.

Next, the operation of the present embodiment in the above configuration will be described. The control program of the present embodiment controls the throttle opening of the first electric expansion valve 141 so that a condenser outlet subcooling degree SC1 approaches a target outlet subcooling degree SCO.

The condenser outlet subcooling degree SC1 is a subcooling degree of the refrigerant flowing out of the condenser 12. The condenser outlet subcooling degree SC1 can be determined using the high pressure P1 and the high-pressure temperature T1. The target outlet subcooling degree SCO is determined with reference to a control map stored in advance in the control device 20 so that the coefficient of performance (COP) of a cycle approaches its maximum value.

Similarly to the first embodiment, the throttle opening of the second electric expansion valve 142 is controlled so that the superheat SH approaches the target superheat SHO. Similarly to the first embodiment, the control mode of the second electric expansion valve 142 is switched. The other configurations are similar to those of the first embodiment.

Therefore, in the refrigeration cycle device 1c, the refrigerant discharged from the discharge port of the compressor 111 flows into the condenser 12 and radiates heat through heat exchange with the outside air. The refrigerant condensed in the condenser 12 flows into the first electric expansion valve 141 and is decompressed. At this time, the throttle opening of the first electric expansion valve 141 is controlled so that the condenser outlet subcooling degree SC1 approaches the target outlet subcooling degree SCO.

The refrigerant decompressed by the first electric expansion valve 141 flows into the intermediate-pressure receiver 13a and is separated into gas and liquid. The gas-phase refrigerant flowing out of the gas-phase refrigerant outflow port of the intermediate-pressure receiver 13a is sucked into the intermediate-pressure suction port of the compressor 111 and compressed again.

The liquid-phase refrigerant flowing out of the liquid-phase refrigerant outflow port of the intermediate-pressure receiver 13a flows into the second electric expansion valve 142 and is decompressed. At this time, the throttle opening of the second electric expansion valve 142 is controlled so that the superheat SH of the outlet-side refrigerant of the evaporator 15 approaches the target superheat SHO.

The refrigerant decompressed by the second electric expansion valve 142 flows into the evaporator 15 and evaporates through heat exchange with the ventilation air. Accordingly, the ventilation air is cooled. The gas-phase refrigerant with a superheat flowing out of the evaporator 15 is sucked into the low-pressure suction port of the compressor 111 and compressed again.

In the inside air conditioning unit, as in the first embodiment, the ventilation air cooled by the evaporator 15 is blown toward an appropriate location in the vehicle interior. This achieves air conditioning in the vehicle interior. In addition, since the refrigeration cycle device 1c of the present embodiment constitutes the gas injection cycle of the internal heat exchange system, the coefficient of performance (COP) of the cycle can be improved.

In the refrigeration cycle device 1c according to the present embodiment, the control mode of the second electric expansion valve 142 is switched as in the first embodiment. Therefore, similarly to the first embodiment, the second electric expansion valve 142 can be appropriately controlled in accordance with the operating condition.

Fifth Embodiment

In the present embodiment, a refrigeration cycle device 1d will be described. The refrigeration cycle device 1d is applied to a vehicle air conditioner with an in-vehicle device temperature adjustment function. In the vehicle air conditioner with an in-vehicle device temperature adjustment function, it is possible to perform not only air conditioning in the vehicle interior but also temperature adjustment for the in-vehicle device. In the vehicle air conditioner of the present embodiment, temperature adjustment for a battery 30 is performed as the in-vehicle device.

The battery 30 is a secondary battery that stores electric power supplied to a plurality of in-vehicle devices operated by electricity. The battery 30 is a battery assembly formed by electrically connecting a plurality of stacked battery cells in series or in parallel and housing the battery cells in a dedicated case. More specifically, the battery cell of the present embodiment is a lithium-ion battery.

The battery 30 generates heat during operation (i.e., during charging and discharging,). The battery 30 tends to decrease in output at low temperatures and deteriorates at high temperatures. Therefore, in the vehicle air conditioner of the present embodiment, when the temperature of the battery 30 rises, the battery 30 is cooled using the cooling capacity of the refrigeration cycle device 1d.

Thus, as shown in the overall configuration diagram of FIG. 8, the refrigeration cycle device 1d includes a battery cooling heat exchanger 153 and a third electric expansion valve 143 in contrast to the refrigeration cycle device 1a described in the second embodiment.

In the refrigeration cycle device 1d, the inlet side of the battery cooling heat exchanger 153 is connected to the outlet side of the first electric expansion valve 141. The battery cooling heat exchanger 153 includes a refrigerant passage through which the refrigerant decompressed by the first electric expansion valve 141 is circulated. The battery cooling heat exchanger 153 is formed integrally with the dedicated case of the battery 30 and can transfer heat between the refrigerant circulating through the refrigerant passage and the battery 30.

Therefore, the battery cooling heat exchanger 153 of the present embodiment is a battery heat exchange part that exchanges heat between the refrigerant decompressed by the first electric expansion valve 141 and the battery 30. The battery cooling heat exchanger 153 is used as an evaporator that evaporates the refrigerant decompressed by the first electric expansion valve 141 to exert a heat absorbing action, thereby cooling the battery 30.

The inlet side of the third electric expansion valve 143 is connected to the outlet of the refrigerant passage of the battery cooling heat exchanger 153. The basic configuration of the third electric expansion valve 143 is similar to that of the electric expansion valve 14 described in the first embodiment. One inflow port side of junction 16b is connected to the outlet of the third electric expansion valve 143.

The refrigerant inlet side of the evaporator 15 is connected to the outlet side of the second electric expansion valve 142. The other inflow port side of the junction 16b is connected to the refrigerant outlet of the evaporator 15. Therefore, in the refrigeration cycle device 1d, the battery cooling heat exchanger 153 and the evaporator 15 are connected in parallel to the refrigerant flow.

Therefore, the first electric expansion valve 141 of the present embodiment is an upstream decompression unit that decompresses one refrigerant divided at the branch 16a and causes the refrigerant to flow out to the inlet side of the battery cooling heat exchanger 153. The third electric expansion valve 143 is a downstream decompression unit that decompresses the refrigerant flowing out of the battery cooling heat exchanger 153.

The second electric expansion valve 142 of the present embodiment is an auxiliary decompression unit that decompresses the other refrigerant divided at the branch 16a. The evaporator 15 of the present embodiment is an auxiliary evaporator that evaporates the refrigerant decompressed by the second electric expansion valve 142.

The first outlet-side pressure sensor 211a is a pressure detector for detecting a first outlet-side pressure Pe1 that is the pressure of the outlet-side refrigerant of the battery cooling heat exchanger 153 and upstream of the third electric expansion valve 143. The first outlet-side temperature sensor 211b is a temperature detector for detecting a first outlet-side temperature Te1 that is the temperature of the outlet-side refrigerant of the battery cooling heat exchanger 153 and upstream of the third electric expansion valve 143.

The second outlet-side pressure sensor 212a is an auxiliary pressure detector for detecting a second outlet-side pressure Pe2 that is the pressure of the outlet-side refrigerant of the evaporator 15. The second outlet-side temperature sensor 212b is an auxiliary temperature detector for detecting a second outlet-side temperature Te2 that is the temperature of the outlet-side refrigerant of the evaporator 15.

The decompression control unit 20b of the present embodiment controls the operations of the first electric expansion valve 141, the second electric expansion valve 142, and the third electric expansion valve 143. As in the second embodiment, the decompression control unit 20b of the present embodiment determines the first superheat SH1, the first delayed superheat SHd1, the second superheat SH2, and the like. Other configurations of the refrigeration cycle device 1d are similar to those of the refrigeration cycle device 1a described in the second embodiment.

Next, the operation of the present embodiment in the above configuration will be described. In the control program of the present embodiment, the throttle opening of the first electric expansion valve 141 is controlled so that the first outlet-side pressure Pe1 of the outlet-side refrigerant of the battery cooling heat exchanger 153 approaches a predetermined battery target pressure PBO. The battery target pressure PBO is determined so that the battery 30 can be appropriately cooled by the battery cooling heat exchanger 153.

The throttle opening of the third electric expansion valve 143 is controlled so that the first superheat SH1 of the outlet-side refrigerant of the battery cooling heat exchanger 153 approaches a predetermined first target superheat SHO1. In the present embodiment, the first target superheat SHO1 is set to 1° C. Similarly to the first embodiment, the control mode of the third electric expansion valve 143 is switched.

The throttle opening of the second electric expansion valve 142 is controlled so that the second superheat SH2 of the outlet-side refrigerant of the evaporator 15 approaches the second target superheat SHO2 determined by the decompression control unit 20b. The other operations are similar to those of the second embodiment.

Therefore, in the refrigeration cycle device 1d, the state of the refrigerant changes as illustrated in a Mollier diagram of FIG. 9. The refrigerant (point a9 in FIG. 9) discharged from compressor 11 flows into condenser 12 and radiates heat through heat exchange with the outside air (from point a9 to point b9 in FIG. 9). The refrigerant condensed in the condenser 12 flows into the receiver 13 and is separated into gas and liquid. The flow of the liquid-phase refrigerant flowing out of the receiver 13 is divided at the branch 16a.

One refrigerant divided at the branch 16a flows into the first electric expansion valve 141 and is decompressed (from point b9 to point c9 in FIG. 9). At this time, the throttle opening of the first electric expansion valve 141 is controlled so that the first outlet-side pressure Pe1 of the outlet-side refrigerant (point d9 in FIG. 9) of the battery cooling heat exchanger 153 approaches the battery target pressure PBO.

The refrigerant decompressed by the first electric expansion valve 141 flows into the battery cooling heat exchanger 153, and evaporates through heat exchanges with the battery 30 (from point c9 to point d9 in FIG. 9). As a result, the battery 30 is cooled.

The refrigerant flowing out of the battery cooling heat exchanger 153 flows into the third electric expansion valve 143 and is decompressed (from point d9 to point e9 in FIG. 9). At this time, the throttle opening of the third electric expansion valve 143 is controlled so that the first superheat SH1 of the outlet-side refrigerant (point d9 in FIG. 9) of the battery cooling heat exchanger 153 approaches the first target superheat SHO1. The refrigerant decompressed by the third electric expansion valve 143 flows into one inflow port of the junction 16b.

The other refrigerant divided at the branch 16a flows into the second electric expansion valve 142 and is decompressed (from point b9 to point f9 in FIG. 9). At this time, the throttle opening of the second electric expansion valve 142 is controlled so that the second superheat SH2 of the outlet-side refrigerant of the evaporator 15 approaches the second target superheat SHO2.

The refrigerant decompressed by the second electric expansion valve 142 flows into the evaporator 15 and evaporates through heat exchanges with the ventilation air (from point f9 to point e9 in FIG. 9). Accordingly, the ventilation air is cooled. The refrigerant flowing out of the evaporator 15 flows into the other inflow port of the junction 16b. The refrigerant flowing out of the junction 16b is sucked into the compressor 11 and compressed again (from point e9 to point a9 in FIG. 9).

As described above, according to the vehicle air conditioner of the present embodiment, it is possible to cool the battery 30 while achieving air conditioning in the vehicle interior.

Furthermore, in the refrigeration cycle device 1d of the present embodiment, since the control mode of the third electric expansion valve 143 is switched as in the first embodiment, the third electric expansion valve 143 can be appropriately controlled in accordance with the operating condition. That is, even in the cycle configuration where the operation of the third electric expansion valve 143 is controlled to adjust the superheat of the refrigerant upstream of the third electric expansion valve 143 as in the present embodiment, similar effects to those of the first embodiment can be obtained.

The battery cooling heat exchanger 153 of the refrigeration cycle device 1d directly exchanges heat between the refrigerant and the battery 30 to cool the battery 30. Therefore, it is effective that the third electric expansion valve 143 can appropriately adjust the first superheat SH1 of the outlet-side refrigerant of the battery cooling heat exchanger 153 to reduce the temperature distribution of the refrigerant in the battery cooling heat exchanger 153 and uniformly cool the battery 30.

The refrigeration cycle device 1d according to the present embodiment includes the branch 16a, the first electric expansion valve 141 as an upstream decompression unit, the second electric expansion valve 142 as an auxiliary decompression unit, the evaporator 15 as an auxiliary evaporator, and the junction 16b.

Accordingly, the refrigerant evaporation temperature at the battery cooling heat exchanger 153 and the refrigerant evaporation temperature at the evaporator 15 can be set to different temperature zones. Therefore, different cooling targets, such as the battery 30 and the ventilation air of the present embodiment, can be cooled in different temperature zones without changing the superheat of the outlet-side refrigerant of the battery cooling heat exchanger 153 or the superheat of the outlet-side refrigerant of the evaporator 15.

In the present embodiment, the example in which the operation of the third electric expansion valve 143 is controlled using the first delayed outlet-side temperature Ted1 has been described, but the present invention is not limited thereto.

For example, the operation of the first electric expansion valve 141 may be controlled using the first delayed outlet-side temperature Ted1. In this case, the first electric expansion valve 141 corresponds to the decompression unit described in the first embodiment, and the battery cooling heat exchanger 153 corresponds to the evaporator described in the first embodiment. The throttle opening of the third electric expansion valve 143 may be controlled so that the first outlet-side pressure Pe1 of the outlet-side refrigerant of the battery cooling heat exchanger 153 approaches the battery target pressure PBO.

The present disclosure is not limited to the embodiment described above and can be variously modified as follows without departing from the spirit of the present disclosure.

In the embodiment described above, the example in which the refrigeration cycle device 1 according to the present disclosure is applied to the vehicle air conditioner has been described, but the application target of the refrigeration cycle device is not limited to the vehicle air conditioner. For example, the present invention may be applied to a stationary air conditioner.

The configuration of the refrigeration cycle device according to the present disclosure is not limited to the configuration disclosed in the embodiment described above.

For example, the compressor 11 is not limited to an electric compressor. For example, an engine-driven compressor driven by a rotational driving force transmitted from an engine may be employed. As the engine-driven compressor, it is possible to employ a variable-volume compressor or the like, which can adjust refrigerant discharge capacity by changing the discharge volume.

In the embodiment described above, the example in which the condenser 12 is employed as the condensing part has been described, but the present invention is not limited thereto. For example, a water refrigerant heat exchange part that exchanges heat between the refrigerant discharged from the compressors 11 and 111 and the heat medium may be employed as the condensing part. Furthermore, a heating heat exchange part that exchanges heat between the heating medium heated in the water refrigerant heat exchange part and the heating target fluid may be disposed in the heating medium circuit that circulates the heating medium.

In the embodiment described above, the example in which the evaporator 15, 151, or 152 is employed as the evaporator has been described, but the present invention is not limited thereto. For example, a water refrigerant heat exchanger that exchanges heat between the refrigerant decompressed in decompression unit 14, 141, or 142 and the heat medium may be employed as the evaporator. Furthermore, a cooling heat exchange part that exchanges heat between the heat medium cooled in the water refrigerant heat exchange part and the cooling target fluid may be disposed in the heat medium circuit that circulates the heat medium.

As the heat medium, a solution containing an ethylene glycol aqueous solution, dimethylpolysiloxane, nanofluid, or the like, an aqueous liquid refrigerant containing an antifreeze liquid, alcohol, or the like, or a liquid medium containing oil or the like can be employed.

As the condenser 12 and the receiver 13, a so-called subcooling condenser may be employed. The subcooling condenser includes a condensing part, a receiver part, and a subcooling portion. Similarly to the condenser 12, the condensing part exchanges heat between the refrigerant and the outside air to condense the refrigerant. Similarly to the receiver 13, the receiver part separates the refrigerant flowing out of the condensing part into gas and liquid, and stores a part of the separated liquid-phase refrigerant as an excess refrigerant in the cycle. The subcooling portion exchanges heat between the liquid-phase refrigerant flowing out of the receiver part and the outside air to subcool the liquid-phase refrigerant.

In the refrigeration cycle device 1c according to the fourth embodiment, the example in which the intermediate-pressure receiver 13a is employed has been described. However, in addition to the intermediate-pressure receiver 13a, a receiver 13 similar to that of the first embodiment may be added to the refrigerant outlet of the condenser 12. When the receiver 13 is added, the throttle opening of the first electric expansion valve 141 may be controlled so that an intermediate pressure Pm, which is the pressure of the refrigerant sucked into the intermediate-pressure suction port of the compressor 111, approaches a target intermediate pressure PMO.

The refrigeration cycle devices 1 to 1d may be configured to be able to switch the refrigerant circuit to execute another operation mode as long as an operation similar to those in the embodiments described above can be executed.

In the embodiment described above, the example in which R1234yf is employed as the refrigerant of the refrigeration cycle device 1 has been described, but the present invention is not limited thereto. For example, R134a, R600a, R410A, R404A, R32, R407C, or the like may be employed. Alternatively, a mixed refrigerant, obtained by mixing a plurality of types of these refrigerants, or the like may be employed. Furthermore, carbon dioxide may be employed as the refrigerant to form a supercritical refrigeration cycle in which the high-pressure side refrigerant pressure is equal to or higher than the critical pressure of the refrigerant.

In the embodiment described above, the example in which the outlet-side pressure sensor 21a that detects the outlet-side pressure Pe is employed as the pressure detector has been described, but the present invention is not limited thereto. As the pressure detector, a detector that detects a physical quantity correlated with the outlet-side pressure Pe can be employed as long as the outlet-side pressure Pe can be detected.

For example, an inlet-side temperature sensor that detects an inlet-side temperature Tei, which is the temperature of the inlet-side refrigerant of the evaporator 15, may be employed as the pressure detector. In this case, a value obtained by subtracting a value corresponding to the pressure loss of the refrigerant in the evaporator 15 from the saturation pressure Pei of the refrigerant at the inlet-side temperature Tei may be set as the outlet-side pressure Pe.

The control mode of the refrigeration cycle device according to the present disclosure is not limited to the control mode disclosed in the embodiment described above.

In the embodiment described above, the refrigeration cycle device 1 capable of executing the absolute value control, the differential control, and the protection control has been described as the control mode of the electric expansion valve 14. However, all the control modes described above need not be executable. If at least the absolute value control can be executed, appropriate control of the decompression unit can be achieved in accordance with various operating conditions.

In the embodiment described above, the example in which the time constant is used as the delay process executed by the decompression control unit 20b has been described, but a moving average or an interval average may be used as the delay process.

In the embodiment described above, the example in which the valve opening differential pressure ΔPe is determined using the saturation pressure Ped of the refrigerant at the delayed outlet-side temperature Ted during the absolute value control has been described. However, the present invention is not limited thereto. For example, the valve opening differential pressure ΔPe may be determined using a saturation pressure Ped of a refrigerant different from the refrigerant circulating in the cycle or a saturation pressure Ped of a mixed refrigerant obtained by mixing a plurality of fluids.

In the embodiment described above, the example in which the throttle opening of the electric expansion valve 14 is changed so that the superheat SH approaches the target superheat SHO based on the deviation between the superheat SH and the target superheat SHO during the differential control has been described. However, the present invention is not limited thereto. During the differential control, the throttle opening of the electric expansion valve 14 may be changed using the deviation between the delayed superheat SHd and the target superheat SHO so that the delayed superheat SHd approaches the target superheat SHO.

In the embodiment described above, the example in which the protection control is executed when the delayed superheat SHd becomes equal to or higher than the upper-limit superheat SHMAX has been described, but the present invention is not limited thereto. The protection control may be executed when the superheat SH becomes equal to or higher than the upper-limit superheat SHMAX.

The means disclosed in each of the embodiments described above may be appropriately combined within a feasible range. For example, in each of the refrigeration cycle devices 1b to 1d described in the third to fifth embodiments, a first decompression unit, a second decompression unit, a first evaporator, and a second evaporator may be disposed as in the second embodiment, and each of the refrigeration cycle devices 1b to 1d may be applied to the dual air-conditioner-type vehicle air conditioner described in the second embodiment. The operations of the first decompression unit and the second decompression unit may be controlled similarly to the second embodiment.

The refrigerant cycle device according to the present disclosure includes the following items or/and features.

(Item 1)

A refrigeration cycle device includes: a decompression unit (14, 142) configured to decompress a refrigerant; an evaporator (15) configured to evaporate the refrigerant decompressed by the decompression unit; a pressure detector (21a) configured to detect an outlet-side pressure (Pe) of the refrigerant at a refrigerant outlet side of the evaporator; a temperature detector (21b) configured to detect an outlet-side temperature (Te) of the refrigerant at the refrigerant outlet side of the evaporator; and a controller configured to control an operation of the decompression unit. In the refrigeration cycle device, the controller is configured to obtain a delayed outlet-side temperature (Ted) by performing a delay process on the outlet-side temperature (Te), and to control the decompression unit by using the outlet-side pressure (Pe) and the delayed outlet-side temperature (Ted).

(Item 2)

In the refrigeration cycle device according to Item 1, the controller determines a superheat (SH) of the refrigerant at the refrigerant outlet side of the evaporator by using the outlet-side pressure (Pe) and the outlet-side temperature (Te), and increases a degree of delay in the delay process in accordance with an increase in the superheat (SH).

(Item 3)

In the refrigeration cycle device according to Item 1 or 2, the controller determines a superheat (SH) of the refrigerant at the refrigerant outlet side of the evaporator by using the outlet-side pressure (Pe) and the outlet-side temperature (Te), and decreases a degree of delay in the delay process in accordance with a decrease in a superheat variation (ΔSH) of the superheat (SH) per a predetermined reference time when the superheat (SH) is equal to or less than a predetermined reference high superheat (KSHh).

(Item 4)

In the refrigeration cycle device according to any one of Items 1 to 3, the controller is configured to perform an absolute value control, in which a target throttle opening of the decompression unit is controlled by using the outlet-side pressure (Pe) and the delayed outlet-side temperature (Ted), and an operation of the decompression unit is controlled to bring an opening of the decompression unit closer to the target throttle opening.

(Item 5)

In the refrigeration cycle device according to any one of Items 1 to 4, the controller is configured to perform a differential control, in which a superheat (SH) of the refrigerant at the refrigerant outlet side of the evaporator is controlled by using the outlet-side pressure (Pe) and the outlet-side temperature (Te), and an operation of the decompression unit is controlled to reduce a difference between the superheat (SH) and a predetermined target superheat (SHO).

(Item 6)

In the refrigeration cycle device according to Item 5, the controller performs the differential control when the superheat (SH) of the refrigerant at the refrigerant outlet side of the evaporator is higher than a predetermined reference high superheat (KSHh) and an absolute value of a superheat variation (ΔSH) of the superheat (SH) per a predetermined reference time is smaller than a predetermined reference variation (KASH).

(Item 7)

In the refrigeration cycle device according to any one of Items 1 to 6, the controller is configured to perform a protection control, in which a delayed superheat (SHd) of the refrigerant at the refrigerant outlet side of the evaporator is determined by using the outlet-side pressure (Pe) and the delayed outlet-side temperature (Ted), and a throttle opening of the decompression unit is increased when the delayed superheat (SHd) becomes equal to or higher than an upper-limit superheat (SHMAX) assumed during a normal operation.

(Item 8)

A refrigeration cycle device includes: a branch (16a) configured to divide a flow of a refrigerant in a refrigerant cycle into separate streams including first and second streams; a first decompression unit (141) configured to decompress the refrigerant in the first stream flowing out of the branch; a first evaporator (151) that evaporates the refrigerant decompressed by the first decompression unit; a second decompression unit (142) configured to decompress the refrigerant in the second stream flowing out of the branch; a second evaporator (152) that evaporates the refrigerant decompressed by the second decompression unit; a first pressure detector (211a) configured to detect a first outlet-side pressure (Pe1) of the refrigerant at a refrigerant outlet side of the first evaporator; a second pressure detector (212a) configured to detect a second outlet-side pressure (Pe2) of the refrigerant at a refrigerant outlet side of the second evaporator; and a first temperature detector (211b) configured to detect a first outlet-side temperature (Te1) of the refrigerant at the refrigerant outlet side of the first evaporator; a second temperature detector (212b) configured to detect a second outlet-side temperature (Te2) of the refrigerant at the refrigerant outlet side of the second evaporator; and a controller (20b) configured to control operations of the first decompression unit and the second decompression unit. In the refrigeration cycle device, the controller controls the first decompression unit based on the first outlet-side pressure (Pe1) and a first delayed outlet-side temperature (Ted1), obtained by performing a first delay process on the first outlet-side temperature (Te1), and controls the second decompression unit based on the second outlet-side pressure (Pe2) and a second delayed outlet-side temperature (Ted2), obtained by performing a second delay process on the second outlet-side temperature (Te2). In addition, the controller is configured to be capable of setting a degree of delay in the first delay process and a degree of delay in the second delay process to different degrees.

(Item 9)

A refrigeration cycle device includes: an evaporator (153) that evaporates a refrigerant; a downstream decompression unit (143) configured to decompress the refrigerant flowing out of the evaporator; a pressure detector (211a) configured to detect an outlet-side pressure (Pe) of the refrigerant at a refrigerant outlet side of the evaporator; a temperature detector (211b) configured to detect an outlet-side temperature (Te) of the refrigerant at the refrigerant outlet side of the evaporator; and a controller (20b) configured to control an operation of the downstream decompression unit. In the refrigeration cycle device, the controller controls the downstream decompression unit based on the outlet-side pressure (Pe) and a delayed outlet-side temperature (Ted) obtained by performing a delay process on the outlet-side temperature (Te).

(Item 10)

The refrigeration cycle device according to Item 9 further includes a branch (16a) that divides a flow of the refrigerant in a refrigerant cycle into separate streams including first and second streams; an upstream decompression unit (141) configured to decompresses the refrigerant in the first stream divided at the branch and to allow the refrigerant to flow out to a refrigerant inlet side of the evaporator (153); an auxiliary decompression unit (142) configured to decompress the refrigerant in the second stream divided at the branch; an auxiliary evaporator (15) that evaporates the refrigerant decompressed in the auxiliary decompression unit; and a junction (16b) configured to merge a flow of the refrigerant flowing out of the evaporator and a flow of the refrigerant flowing out of the auxiliary evaporator.

Although the present disclosure has been described in accordance with examples, it is understood that the present disclosure is not limited to the examples and structures. The present disclosure also includes various modifications, and modifications within an equivalent scope. In addition, various combinations and modes, and other combinations and modes including only one element, more elements, or less elements are also within the scope and idea of the present disclosure.

Number	Date	Country	Kind
2022-108326	Jul 2022	JP	national
2022-206823	Dec 2022	JP	national

	Number	Date	Country
Parent	PCT/JP2023/023894	Jun 2023	WO
Child	19005719		US

REFRIGERATION CYCLE DEVICE

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