WO2015107876A1

WO2015107876A1 - Heat pump cycle

Info

Publication number: WO2015107876A1
Application number: PCT/JP2015/000069
Authority: WO
Inventors: 道夫西川; 稲葉　淳; 紘明河野; 桑原　幹治; 祐一加見
Original assignee: 株式会社デンソー
Priority date: 2014-01-14
Filing date: 2015-01-08
Publication date: 2015-07-23
Also published as: JP2015132428A; JP6119616B2

Abstract

This heat pump cycle switches between a first heating operation mode and a second operation mode. When a heating load is increased and a compressor (11) is sped up during the first heating operation mode, it is determined that a refrigerant containing a liquid-phase refrigerant flows into an intermediate pressure port (11b) of the compressor (11), and the first heating operation mode is switched to the second heating operation mode. In the second heating operation mode, a gas-phase-side valve (18) closes the pathway leading the refrigerant to the intermediate pressure port (11b), and so it is possible to prevent the inflow of liquid-phase refrigerant to the compressor (11).

Description

Heat pump cycle

Cross-reference of related applications

This application is based on Japanese Patent Application No. 2014-004356 filed on January 14, 2014, the disclosure of which is incorporated herein by reference.

This disclosure relates to a heat pump cycle.

Conventionally, as a vehicle air conditioner applied to a vehicle such as an electric vehicle in which it is difficult to secure a heat source for heating the vehicle interior, air blown into the vehicle interior by a heat pump cycle (vapor compression refrigeration cycle) is used. What heats and heats a vehicle interior is known.

For example, Patent Documents 1 and 2 disclose heat pump cycles that are applied to this type of vehicle air conditioner and that can switch between a refrigerant circuit during cooling operation and a refrigerant circuit during heating operation. In the heat pump cycle, during heating operation, the refrigerant is boosted in multiple stages by two compression mechanisms, a low-stage compression mechanism and a high-stage compression mechanism, and the intermediate-pressure gas-phase refrigerant of the cycle is discharged from the low-stage compression mechanism. The operation is switched to a so-called gas injection cycle (economizer refrigeration cycle) in which the discharged refrigerant is combined and sucked into the high-stage compression mechanism. Thereby, the cycle efficiency (COP) at the time of heating operation is improved.

Specifically, the heat pump cycle disclosed in Patent Documents 1 and 2 includes a high-stage expansion valve, a gas-liquid separator, a gas-phase refrigerant passage, a fixed throttle (that is, a low-stage decompression section), a liquid-phase refrigerant passage. An evaporator, a bypass valve, a gas-phase refrigerant control valve, and the like. The high stage side expansion valve depressurizes the high-pressure refrigerant until it becomes an intermediate-pressure refrigerant. The gas-liquid separator separates the gas-liquid of the refrigerant decompressed by the high stage side expansion valve. The gas-phase refrigerant passage guides the gas-phase refrigerant separated by the gas-liquid separator to the intermediate pressure port of the compressor. The fixed throttle depressurizes the liquid-phase refrigerant separated by the gas-liquid separator. The liquid phase refrigerant passage allows the liquid phase refrigerant separated by the gas-liquid separator to flow through the fixed throttle. The evaporator evaporates the refrigerant flowing out from the fixed throttle and the liquid phase refrigerant passage. The bypass valve opens and closes the liquid phase refrigerant passage. The gas phase refrigerant control valve opens and closes the gas phase refrigerant passage.

In the heat pump cycle disclosed in Patent Document 1, the bypass valve and the gas-phase refrigerant control valve are integrated, and the gas-phase refrigerant control valve is operated by utilizing the pressure change caused by the on-off valve operation of the bypass valve. During the gas injection operation, the bypass valve closes the liquid phase refrigerant passage, and the gas phase refrigerant control valve opens the gas phase refrigerant passage.

On the other hand, the heat pump cycle disclosed in Patent Document 2 uses an electromagnetic valve type bypass valve and an electromagnetic valve type gas phase refrigerant control valve. During the gas injection operation, the bypass valve closes the liquid phase refrigerant passage, and the gas phase refrigerant control valve opens the gas phase refrigerant passage.

JP 2013-092355 A JP 2012-181005 A

However, according to studies by the inventors of the present disclosure, the diameter of the fixed throttle is such that an appropriate amount of refrigerant flows to the evaporator through the fixed throttle in a steady operation state where the bypass valve closes the liquid-phase refrigerant passage. Is designed. For this reason, in a transient operation region where the rotation speed of the compressor suddenly increases in the gas injection operation state, the balance between the amount of refrigerant flowing through the fixed throttle and the amount of refrigerant flowing into the gas-liquid separator is temporarily The liquid phase refrigerant accumulates in the gas-liquid separator.

Therefore, in the transient operation region during the gas injection operation, the liquid phase refrigerant accumulated in the gas-liquid separator flows into the intermediate pressure port of the compressor through the gas phase refrigerant passage. Thereby, the refrigeration oil in a compressor is washed out and the sliding part of a compressor will be in a poor lubrication state. As a result, the sliding portion of the compressor may be worn out or even locked.

In view of the above points, the present disclosure provides a heat pump cycle capable of preventing liquid-phase refrigerant from flowing into a compressor and improving cycle efficiency (COP) by gas injection operation in a heat pump cycle performing gas injection operation. The purpose is to do.

The heat pump cycle of the present disclosure compresses the low-pressure refrigerant sucked from the suction port, discharges it as a high-pressure refrigerant from the discharge port, and introduces an intermediate-pressure port that flows in the intermediate-pressure refrigerant in the cycle and joins the refrigerant in the compression process. A high-pressure refrigerant discharged from the discharge port and a high-pressure refrigerant discharged from the discharge port to heat-exchange the heat-exchange target fluid and a high-pressure refrigerant flowing out of the use-side heat exchanger A high-stage decompression unit that decompresses the refrigerant until it becomes an intermediate-pressure refrigerant, a gas-liquid separation unit that separates the gas-liquid of the intermediate-pressure refrigerant decompressed by the high-stage decompression unit, and a gas separated by the gas-liquid separation unit A gas-phase refrigerant passage for guiding the phase refrigerant to the intermediate pressure port, a gas-phase refrigerant control valve for opening and closing the gas-phase refrigerant passage, a low-stage decompression section for decompressing the liquid-phase refrigerant separated in the gas-liquid separation section, Refrigerant depressurized in the low-stage decompression section An evaporator that evaporates and flows out as a low-pressure refrigerant to the suction port side, and a gas phase refrigerant control valve that opens and an intermediate-pressure refrigerant flows into the intermediate-pressure port during the gas injection operation. A refrigerant state determination unit that determines whether or not a refrigerant containing a refrigerant flows; and a refrigerant state determination unit that determines whether or not a refrigerant containing a liquid phase refrigerant flows into the gas phase refrigerant passage; And an inflow suppressing part for suppressing the flow of the refrigerant flowing into the intermediate pressure port.

According to this, when it is determined that the refrigerant containing the liquid phase refrigerant flows into the gas phase refrigerant passage, the flow of the refrigerant flowing into the intermediate pressure port is suppressed. For this reason, the inflow of the liquid phase refrigerant into the compressor can be prevented, and problems due to the inflow of the liquid phase refrigerant into the compressor can be prevented. Further, in a situation where it is determined that the refrigerant containing the liquid-phase refrigerant does not flow into the gas-phase refrigerant passage, the gas injection operation can be continued to improve the cycle efficiency (COP).

It is a whole block diagram which shows the refrigerant circuit at the time of the cooling operation mode of the heat pump cycle of 1st Embodiment, and the dehumidification heating operation mode. It is a whole block diagram which shows the refrigerant circuit at the time of the 1st heating operation mode of the heat pump cycle of 1st Embodiment. It is a whole block diagram which shows the refrigerant circuit at the time of the 2nd heating operation mode of the heat pump cycle of 1st Embodiment. It is typical sectional drawing in the non-energized state of the integrated valve of 1st Embodiment. It is typical sectional drawing in the energized state of the integrated valve of 1st Embodiment. It is the elements on larger scale explaining the conditions from which the gas-phase side valve body of 1st Embodiment begins to open. It is the elements on larger scale explaining the conditions which the vapor phase side valve body of 1st Embodiment continues opening. It is a flowchart which shows the flow of the liquid phase refrigerant | coolant inflow prevention process of 1st Embodiment. It is typical sectional drawing in the non-energized state of the integrated valve of 9th Embodiment. It is a typical fragmentary sectional view of the integrated valve which shows the 1st modification of 9th Embodiment. It is a typical fragmentary sectional view of the integrated valve which shows the 2nd modification of 9th Embodiment. It is a typical fragmentary sectional view in the other operation state of the integrated valve which shows the 2nd modification of 9th Embodiment. It is a whole block diagram which shows the refrigerant circuit at the time of the 1st heating operation mode of the heat pump cycle of 10th Embodiment. It is a whole block diagram which shows the refrigerant circuit at the time of the 1st heating operation mode of the heat pump cycle of 11th Embodiment. It is a schematic diagram of the heat pump cycle of 12th Embodiment. It is sectional drawing which shows the operating state at the time of electricity supply of the integrated valve of 12th Embodiment. It is sectional drawing which shows the operation state at the time of the deenergization of the integrated valve of 12th Embodiment. It is sectional drawing which shows the other operating state at the time of the deenergization of the integrated valve of 12th Embodiment. It is a schematic diagram of the heat pump cycle of 13th Embodiment. It is a schematic diagram of the heat pump cycle of 14th Embodiment. It is a flowchart which shows the flow of the liquid phase refrigerant | coolant inflow prevention process of 15th Embodiment.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals in the drawings.
(First embodiment)
The first embodiment will be described with reference to FIGS. In this embodiment, the heat pump cycle 10 provided with the integrated valve 14 of this indication is applied to the vehicle air conditioner 1 of the electric vehicle which obtains the driving force for vehicle travel from the travel electric motor. In the present embodiment, the heat pump cycle 10 is a vapor compression refrigeration cycle. This heat pump cycle 10 cools or heats the air blown into the vehicle interior, which is a space to be air-conditioned, in the vehicle air conditioner 1. Therefore, the heat exchange target fluid of this embodiment is air.

Further, the heat pump cycle 10 is shown in the overall configuration diagram of FIG. 1, the refrigerant circuit in the cooling operation mode (cooling operation mode for cooling air) for cooling the vehicle interior, and the overall configuration diagram of FIGS. 2 and 3. The refrigerant circuit in the heating operation mode (heating operation mode for heating air) for heating the vehicle interior can be switched. In FIGS. 1 to 3, the refrigerant flow in each operation mode is indicated by solid arrows.

The heat pump cycle 10 employs an HFC refrigerant (specifically, R134a) as the refrigerant, and constitutes a vapor compression subcritical refrigeration cycle in which the high-pressure refrigerant pressure does not exceed the refrigerant critical pressure. Yes. An HFO refrigerant (for example, R1234yf) or the like may be employed. Furthermore, refrigeration oil for lubricating the compressor 11 is mixed in the refrigerant, and a part of the refrigeration oil circulates in the cycle together with the refrigerant.

Among the components of the heat pump cycle 10, the compressor 11 is located in the hood of the vehicle, and inhales, compresses and discharges the refrigerant in the heat pump cycle 10. The compressor 11 accommodates two compression mechanisms, a low-stage compression mechanism and a high-stage compression mechanism, and an electric motor that rotationally drives both compression mechanisms in a housing that forms an outer shell thereof. Is a two-stage booster type electric compressor configured as described above.

The housing of the compressor 11 has a suction port 11a for sucking low-pressure refrigerant from the outside of the housing into the low-stage compression mechanism, and an intermediate-pressure refrigerant flows from the outside of the housing to the inside of the housing to compress from low pressure to high pressure. An intermediate pressure port 11b for joining the refrigerant and a discharge port 11c for discharging the high-pressure refrigerant discharged from the high-stage compression mechanism to the outside of the housing are provided.

More specifically, the intermediate pressure port 11b is connected to the refrigerant discharge port of the low-stage compression mechanism (that is, the refrigerant suction port of the high-stage compression mechanism). Various types such as a scroll type compression mechanism, a vane type compression mechanism, and a rolling piston type compression mechanism can be adopted as the low stage side compression mechanism and the high stage side compressor.

The operation (rotation speed) of the electric motor is controlled by a control signal output from a control device (air conditioning control device) 40 described later. As the electric motor, either an AC motor or a DC motor may be adopted. And the refrigerant | coolant discharge capability of the compressor 11 is changed by controlling rotation speed. Therefore, in this embodiment, the electric motor constitutes the discharge capacity changing unit of the compressor 11.

In addition, in this embodiment, although the compressor 11 which accommodated two compression mechanisms in one housing is employ | adopted, the format of a compressor is not limited to this. That is, if the intermediate pressure refrigerant can be introduced from the intermediate pressure port 11b and merged with the refrigerant in the compression process from low pressure to high pressure, one fixed capacity type compression mechanism and the compression mechanism are provided inside the housing. An electric compressor configured to accommodate an electric motor that rotationally drives the motor may be used.

Further, two compressors are connected in series, and the suction port of the low-stage compressor disposed on the low-stage side serves as the suction port 11a, and the discharge port of the high-stage compressor disposed on the high-stage side serves as the suction port 11a. The discharge port 11c may be used. In this case, the intermediate pressure port 11b is provided at the connection portion connecting the discharge port of the low-stage compressor and the suction port of the high-stage compressor, and both the low-stage compressor and the high-stage compressor are used. One two-stage booster compressor is configured.

The refrigerant inlet of the indoor condenser 12 is connected to the discharge port 11 c of the compressor 11. The indoor condenser 12 is located in a case (air conditioning case) 31 of an air conditioning unit (indoor air conditioning unit) 30 of the vehicle air conditioner 1 to be described later, and from the compressor 11 (specifically, a high stage compression mechanism). It functions as a radiator that radiates the discharged high-temperature and high-pressure refrigerant. That is, the indoor condenser 12 is a use side heat exchanger that heats air that has passed through an indoor evaporator 23 described later.

The refrigerant outlet of the indoor condenser 12 is connected to an inlet of a high stage side expansion valve 13 as a high stage side pressure reducing section that decompresses the high pressure refrigerant flowing out of the indoor condenser 12 until it becomes an intermediate pressure refrigerant. The high-stage expansion valve 13 is an electric variable throttle mechanism having a valve body that can change the throttle opening degree and an electric actuator that includes a stepping motor that changes the throttle opening degree of the valve body.

More specifically, in the high stage side expansion valve 13, when the refrigerant is in a throttle state in which the refrigerant is depressurized, the throttle opening changes within a range where the cross-sectional area of the throttle passage becomes an equivalent diameter φ0.5 to φ3 mm. Furthermore, when the throttle opening is fully opened, the cross-sectional area of the throttle passage can be ensured to have an equivalent diameter of about 10 mm so that the refrigerant decompression action is not exhibited. The operation of the high stage side expansion valve 13 is controlled by a control signal output from the control device 40. A refrigerant inlet 141 a of the integrated valve 14 is connected to the outlet of the high stage side expansion valve 13.

The integrated valve 14 includes a gas-liquid separation unit (gas-liquid separation space 141b), a gas-phase refrigerant-side valve element (gas-phase-side valve element) 18, a valve (first bypass valve 15), and a decompression unit, which are integrated with each other. (Aperture 17) or the like. The gas-liquid separation space 141 b separates the gas-liquid refrigerant flowing out from the high stage expansion valve 13. The gas phase side valve element 18 opens and closes a gas phase refrigerant passage through which the gas phase refrigerant separated in the gas-liquid separation space 141b flows. The first bypass valve 15 opens and closes a liquid-phase refrigerant passage through which the liquid-phase refrigerant separated in the gas-liquid separation space 141b flows. The throttle 17 depressurizes the liquid-phase refrigerant separated in the gas-liquid separation space 141b.

In other words, in the integrated valve 14, a part of the constituent devices necessary for causing the heat pump cycle 10 to function as a gas injection cycle is integrated. Furthermore, the integrated valve 14 is a refrigerant circuit switching part which switches the refrigerant circuit of the refrigerant | coolant which circulates through a cycle.

The detailed configuration of the integrated valve 14 will be described with reference to FIGS. In addition, the up and down arrows in FIGS. 4 and 5 indicate the up and down directions in a state where the integrated valve 14 is mounted on the vehicle air conditioner 1.

The integrated valve 14 includes a body 140 that accommodates the gas-phase side valve body 18 as the gas-phase refrigerant control valve, the first bypass valve 15 and the like and forms an outer shell of the integrated valve 14. The body 140 includes a lower body 141 located on the lower side of the integrated valve 14 and an upper body 142 attached and fixed to the lower body 141 so as to be located above the lower body 141.

First, the lower body 141 is formed of a substantially bottomed cylindrical metal block whose axial direction extends in the vertical direction. On the outer wall surface of the lower body 141, there is formed a refrigerant inlet 141a through which the refrigerant flowing out from the high stage side expansion valve 13 flows into the inside. The refrigerant inlet 141 a communicates with a gas-liquid separation space 141 b formed inside the lower body 141. The gas-liquid separation space 141b is formed in a substantially cylindrical shape whose axial direction extends in the vertical direction.

Further, the refrigerant passage extending from the refrigerant inlet 141a to the gas-liquid separation space 141b has a circular cross section when viewed from the axial direction (vertical direction in the present embodiment) of the gas-liquid separation space 141b. It extends in the tangential direction of the inner wall surface. Therefore, the refrigerant that has flowed into the gas-liquid separation space 141b from the refrigerant inlet 141a flows so as to swirl along the inner wall surface having a circular cross section of the gas-liquid separation space 141b.

Then, the gas-liquid refrigerant flowing into the gas-liquid separation space 141b is separated by the action of the centrifugal force generated by the swirling flow, and the separated liquid-phase refrigerant falls to the lower side of the gas-liquid separation space 141b by the action of gravity. To do. In other words, the gas-liquid separation space 141b of the present embodiment constitutes a centrifugal gas-liquid separation unit.

In addition, the diameter of the gas-liquid separation space 141b is set to a diameter that is 1.5 times or more and about 3 times or less the diameter of the refrigerant pipe connected to the refrigerant inlet 141a, for example. Is miniaturized.

More specifically, the internal volume of the gas-liquid separation space 141b of the present embodiment is necessary for the cycle to exert its maximum capacity from the enclosed refrigerant volume when the amount of refrigerant enclosed in the cycle is converted into the liquid phase. It is set smaller than the surplus refrigerant volume obtained by subtracting the required maximum refrigerant volume when the refrigerant amount is converted into the liquid phase. For this reason, the internal volume of the gas-liquid separation space 141b of the present embodiment is a volume that cannot substantially store surplus refrigerant even if a load fluctuation occurs in the cycle and the refrigerant circulation flow rate circulating in the cycle fluctuates. It has become.

In the lowermost part of the gas-liquid separation space 141b of the lower body 141, a separated liquid phase refrigerant outlet hole 141c through which the separated liquid phase refrigerant flows out to the first liquid phase refrigerant passage 141d side is formed. The first liquid-phase refrigerant passage 141d is positioned below the gas-liquid separation space 141b and guides the liquid-phase refrigerant separated in the gas-liquid separation space 141b to the liquid-phase refrigerant outlet 141e side that allows the liquid-phase refrigerant to flow out of the integrated valve 14. It is a refrigerant passage.

More specifically, the first liquid-phase refrigerant passage 141d is a through-hole having a circular cross section that extends in a direction perpendicular to the axial direction of the gas-liquid separation space 141b (horizontal direction in the present embodiment). The first liquid-phase refrigerant passage 141d is formed so as to pass through the center of the lower body 141 and penetrate the lower body 141.

Accordingly, the first liquid phase refrigerant passage 141d extends perpendicular to the axial direction of the gas-liquid separation space 141b, and the refrigerant flowing into the first liquid phase refrigerant passage 141d from the separation liquid phase refrigerant outlet hole 141c is substantially perpendicular. The flow direction is changed to flow toward the liquid-phase refrigerant outlet 141e and the throttle 17 side. Further, the opening on one end side of the through hole constitutes a liquid-phase refrigerant outlet 141e. The diaphragm 17 corresponds to the low-stage decompression unit of the present disclosure.

The first liquid phase refrigerant passage 141d has a first bypass valve 15 that opens and closes the first liquid phase refrigerant passage 141d, and a first bypass valve 15 toward the side where the first liquid phase refrigerant passage 141d is closed. A spring (elastic member) 15a made of a coil spring for applying a load is accommodated.

With respect to the first bypass valve 15, the spring 15a is a valve seat portion 141f formed in a first liquid-phase refrigerant passage 141d with a resinous annular seal member 15b located at the tip of the first bypass valve 15. Apply a load in the direction to improve the sealing performance. The valve seat 141f is formed in an annular shape that fits the seal member 15b.

Furthermore, the first bypass valve 15 is connected to an operating member (armature) of the solenoid actuator 16 through a shaft 15c. Hereinafter, the solenoid actuator 16 is simply referred to as a solenoid 16. The solenoid 16 is an electromagnetic mechanism that generates electromagnetic force by supplying electric power and displaces the operating member. The operation of the solenoid 16 is controlled by a control voltage output from the control device 40.

In the present embodiment, when the control device 40 supplies power to the solenoid 16, a load on the side of opening the first liquid-phase refrigerant passage 141d is applied to the first bypass valve 15 via the shaft 15c by the electromagnetic force acting on the operating member. . And when the load by this electromagnetic force exceeds the load by the spring 15a, as shown in FIG. 5, the 1st bypass valve 15 displaces and the 1st liquid phase refrigerant path 141d is opened.

That is, the solenoid 16, the first bypass valve 15, the valve seat portion 141f of the first liquid phase refrigerant passage 141d, and the like of this embodiment constitute a so-called normally closed electromagnetic valve. Further, the solenoid 16 also functions as a closing member that closes the opening on the other end side of the through hole that constitutes the first liquid-phase refrigerant passage 141d described above.

Further, in the lower body 141, when the first bypass valve 15 closes the first liquid-phase refrigerant passage 141d, the liquid-phase refrigerant separated in the gas-liquid separation space 141b is depressurized to the liquid-phase refrigerant outlet 141e side. A throttle 17 is formed to flow out to the bottom. More specifically, the throttle 17 is disposed in parallel with the refrigerant passage formed in the valve seat portion 141f.

As the throttle 17, a nozzle or an orifice having a fixed throttle opening can be used. Here, in a fixed throttle such as a nozzle or an orifice, the sectional area of the throttle passage suddenly decreases or expands rapidly, so that the fixed throttle is changed as the pressure difference between the upstream side and the downstream side (differential pressure between the inlet and outlet) changes. The flow rate of the passing refrigerant and the dryness of the fixed throttle upstream refrigerant can be self-adjusted (balanced).

Specifically, when the pressure difference between the upstream side and the downstream side is relatively large, the dryness of the refrigerant on the upstream side of the throttle 17 increases as the required circulating refrigerant flow rate that requires circulation of the cycle decreases. Balance to be. On the other hand, when the pressure difference is relatively small, it is balanced so that the dryness of the fixed throttle upstream side refrigerant decreases as the required circulating refrigerant flow rate increases.

However, when the dryness of the refrigerant upstream of the throttle 17 becomes large, when the outdoor heat exchanger 20 functions as an evaporator, the heat absorption amount (refrigeration capacity) of the refrigerant in the outdoor heat exchanger 20 decreases, and the cycle The coefficient of performance (COP) will deteriorate. Therefore, in the present embodiment, even if the necessary circulating refrigerant flow rate changes due to cycle load fluctuations in the heating operation mode, the dryness X of the refrigerant upstream of the throttle 17 becomes 0.1 or less, and the COP is deteriorated. Suppressed.

In other words, in the throttle 17 of the present embodiment, even if the refrigerant circulation flow rate and the differential pressure between the inlet and outlet of the throttle 17 change within a range assumed when a load fluctuation occurs in the heat pump cycle 10, the upstream refrigerant of the throttle 17 A dry degree X of which is self-adjusted to 0.1 or less is employed.

Next, the upper body 142 is formed of a substantially cylindrical metal block body having an outer diameter equivalent to that of the lower body 141. In the upper body 142, a gas-phase refrigerant passage 142b that leads the gas-phase refrigerant separated in the gas-liquid separation space 141b to the gas-phase refrigerant outlet 142a that flows out of the integrated valve 14 and the gas-liquid separation space 141b and the gas are separated. A separated gas-phase refrigerant outflow pipe portion 142c and the like are provided to communicate with the phase refrigerant passage 142b.

The separated gas-phase refrigerant outflow pipe portion 142c is formed in a round tubular shape, and is located coaxially with the gas-liquid separation space 141b when the upper body 142 and the lower body 141 are integrated. Therefore, the refrigerant that has flowed into the gas-liquid separation space 141b swirls around the separated gas-phase refrigerant outflow pipe portion 142c.

Further, the lowermost end portion of the separated gas-phase refrigerant outflow pipe portion 142c extends so as to be positioned inside the gas-liquid separation space 141b, and the gas-liquid separation space 141b is separated from the lowermost end portion. A separated gas-phase refrigerant outlet hole 142d through which the phase refrigerant flows out is formed. Therefore, the first liquid-phase refrigerant passage 141d and the throttle 17 are located below the separated vapor-phase refrigerant outlet hole 142d.

The gas-phase refrigerant passage 142b is located above the gas-liquid separation space 141b and the separated gas-phase refrigerant outflow pipe portion 142c. Similarly to the first liquid-phase refrigerant passage 141d, the gas-phase refrigerant passage 142b is a through-hole having a circular cross section that extends in a direction perpendicular to the axial direction of the gas-liquid separation space 141b (horizontal direction in the present embodiment). The gas-phase refrigerant passage 142d is formed so as to pass through the center of the upper body 142 and penetrate the upper body 142.

Furthermore, the opening on one end side of the through hole constitutes a gas-phase refrigerant outlet 142a. A gas phase side valve body 18 for opening and closing the gas phase refrigerant passage 142b is accommodated in the gas phase refrigerant passage 142b. The gas-phase side valve element 18 is configured by a differential pressure valve that is displaced by a pressure difference between the refrigerant pressure on the liquid-phase refrigerant outlet 141e side and the refrigerant pressure on the gas-phase refrigerant passage 142b side.

Specifically, the through hole is partitioned by a body portion 18a of the gas phase side valve body 18 into a space forming the gas phase refrigerant passage 142b and a space forming the back pressure chamber 142e. The refrigerant pressure on the liquid-phase refrigerant outlet 141e side is guided to the back pressure chamber 142e via the pressure introduction passage 19.

The body portion 18a is formed in a columnar shape, receives the refrigerant pressure on the gas phase refrigerant passage 142b side at the end face on one end side in the axial direction (gas phase refrigerant outlet 142a side), and on the end face on the other end side in the axial direction. The refrigerant pressure on the back pressure chamber 142e side is received. Further, the outer diameter of the body portion 18a is slightly smaller than the inner diameter of the gas-phase refrigerant passage 142b, and both are in a clearance fit. Thereby, the gas phase side valve element 18 can be displaced in the gas phase refrigerant passage 142b.

The pressure introduction passage 19 is formed by a communication passage formed in both the lower body 141 and the upper body 142 when the upper body 142 and the lower body 141 are integrated. Furthermore, the longitudinal direction of the pressure introducing passage 19 is parallel to the axial direction of the gas-liquid separation space 141b and the separated gas-phase refrigerant outflow pipe portion 142c. Thereby, the pressure introduction passage 19 is not made into a complicated passage shape, and the integrated valve 14 as a whole is reduced in size.

A spring (elastic member) 18b and a stopper (regulating member) 18c are accommodated in the back pressure chamber 142e. The spring 18b is a coil spring that applies a load to the gas-phase side valve element 18 on the side where the gas-phase refrigerant passage 142b is closed. The stopper 18c restricts the displacement of the gas phase side valve element 18 when the gas phase side valve element 18 opens the gas phase refrigerant passage 142b.

The spring 18b is a tapered valve seat portion formed in the gas-phase refrigerant passage 142b with a seal member 18d made of an O-ring located at the tip of the gas-phase side valve body 18 with respect to the gas-phase side valve body 18. A load is applied in a direction to increase the sealing performance by pressing against 142f. The direction in which the sealing property is improved is the direction in which the gas phase side valve element 18 closes the gas phase refrigerant passage 142b.

The stopper 18c regulates the displacement of the gas phase side valve body 18 to prevent the body portion 18a of the gas phase side valve body 18 from closing the pressure introduction passage 19, and the gas phase It is a closing member that closes the opening on the other end side of the through hole that forms the refrigerant passage 142b.

Here, the operation of the gas-phase-side valve element 18 will be described with reference to FIGS.

First, when power is supplied to the solenoid 16, the refrigerant pressure in the gas-phase refrigerant passage 142b indicated by P2 in FIG. 5 becomes the pressure of the gas-phase refrigerant separated in the gas-liquid separation space 141b, and is indicated by P3. The refrigerant pressure on the liquid phase refrigerant outlet 141e side (the refrigerant pressure in the back pressure chamber 142e) is the pressure of the liquid phase refrigerant separated in the gas-liquid separation space 141b.

Therefore, the refrigerant pressure P2 on the gas-phase refrigerant passage 142b side and the refrigerant pressure P3 on the liquid-phase refrigerant outlet 141e side (the refrigerant pressure in the back pressure chamber 142e) are substantially equal. As a result, when electric power is supplied to the solenoid 16, the gas-phase side valve element 18 closes the gas-phase refrigerant passage 142b by the load Fsp received from the spring 18b.

In other words, when electric power is supplied to the solenoid 16 and the first bypass valve 15 opens the first liquid refrigerant passage 141d, the refrigerant pressure P2 on the gas phase refrigerant passage 142b side and the first bypass valve 15 The gas phase side valve element 18 closes the gas phase refrigerant passage 142b in balance with the refrigerant pressure P3 on the liquid phase refrigerant outlet 141e side that has flowed out.

1 to 3, the intermediate pressure port 11b of the compressor 11 is connected to the gas-phase refrigerant outlet 142a of the integrated valve 14. For this reason, when the gas phase side valve element 18 closes the gas phase refrigerant passage 142b during the operation of the compressor 11, the refrigerant pressure P1 on the gas phase refrigerant outlet 142a side becomes the suction pressure of the compressor 11. Therefore, in FIG. 5, the relationship of P1 <P2 is established.

For this reason, when the gas phase side valve element 18 closes the gas phase refrigerant passage 142b during the operation of the compressor 11, the refrigerant pressure P2 in the gas phase refrigerant passage 142b and the refrigerant pressure P3 on the liquid phase refrigerant outlet 141e side are slightly changed. Even if this occurs, the gas-phase refrigerant passage 142b is kept closed until no power is supplied to the solenoid 16.

Next, when power is not supplied to the solenoid 16, the refrigerant pressure on the gas-phase refrigerant outlet 142a side indicated by P1 in FIG. 6 becomes the refrigerant pressure on the intermediate pressure port 11b side of the compressor 11, and the gas-phase refrigerant indicated by P2 The refrigerant pressure in the passage 142b becomes an intermediate pressure reduced by the high stage side expansion valve 13, and the refrigerant pressure on the liquid-phase refrigerant outlet 141e side (refrigerant pressure in the back pressure chamber 142e) indicated by P3 is reduced by the throttle 17. It becomes the pressure after being done.

Therefore, the pressure difference between the refrigerant pressure P2 in the gas-phase refrigerant passage 142b and the refrigerant pressure P3 on the liquid-phase refrigerant outlet 141e side is expanded to satisfy the relationship shown in the following formula F1, whereby the gas-phase side valve body 18 is The gas phase refrigerant passage 142b starts to open.

S2 × (P2-P3)> S1 × (P3-P1) + Fsp + Ffr (F1)
S <b> 1 is an area when the gas-phase refrigerant outlet 142 a is projected in the axial direction of the gas-phase side valve body 18. S <b> 2 is a cross-sectional area of an axially vertical cross section of the body portion 18 a of the gas phase side valve body 18. Ffr is a frictional force (friction) when the gas phase side valve element 18 is displaced.

When the gas-phase side valve body 18 opens the gas-phase refrigerant passage 142b, the refrigerant pressure on the gas-phase refrigerant outlet 142a side indicated by P1 in FIG. 7 and the refrigerant pressure in the gas-phase refrigerant passage 142b indicated by P2 are gas-liquid. The pressure of the gas-phase refrigerant separated in the separation space 141b becomes the pressure after the pressure in the liquid refrigerant outlet 141e side indicated by P3 (the refrigerant pressure in the back pressure chamber 142e) is reduced by the throttle 17. It becomes.

Accordingly, the refrigerant pressure P3 in the back pressure chamber 142e is lower than the refrigerant pressure P2 in the gas phase refrigerant passage 142b, and the relationship shown by the following formula F2 is established, so that the gas phase side valve body 18 passes through the gas phase refrigerant passage 142b. The open state is maintained.

S2 × (P2-P3)> Fsp (F2)
In other words, when power is not supplied to the solenoid 16 and the first bypass valve 15 closes the first liquid-phase refrigerant passage 141d, the refrigerant pressure P2 on the gas-phase refrigerant passage 142b side and the refrigerant flowing out from the throttle 17 The gas phase side valve element 18 opens the gas phase refrigerant passage 142b based on the pressure difference with the pressure P3.

It should be noted that the refrigerant pipe extending from the gas phase refrigerant outlet 142a of the integrated valve 14 to the intermediate pressure port 11b of the compressor 11 only allows the refrigerant to flow from the integrated valve 14 to the intermediate pressure port 11b of the compressor 11. Not check valve is arranged. This prevents the refrigerant from flowing backward from the compressor 11 side to the integrated valve 14 side. This check valve may be integrated with the integrated valve 14 or the compressor 11.

Also, as shown in FIGS. 1 to 3, the refrigerant inlet of the outdoor heat exchanger 20 is connected to the liquid-phase refrigerant outlet 141e of the integrated valve 14. Therefore, the refrigerant that has flowed out of the first liquid-phase refrigerant passage 141d and the refrigerant that has flowed out of the throttle 17 flow into the outdoor heat exchanger 20.

The outdoor heat exchanger 20 is located in the bonnet and exchanges heat between the refrigerant circulating inside and the outside air blown from the blower fan 21. The outdoor heat exchanger 20 functions as an evaporator that evaporates low-pressure refrigerant and exerts an endothermic effect at least in the heating operation mode, and functions as a radiator that radiates high-pressure refrigerant in the cooling operation mode and the like. It is an exchanger.

The refrigerant inlet of the cooling expansion valve 22 is connected to the refrigerant outlet of the outdoor heat exchanger 20. The cooling expansion valve 22 decompresses the refrigerant that flows out of the outdoor heat exchanger 20 and flows into the indoor evaporator 23 in the cooling operation mode or the like. The basic configuration of the cooling expansion valve 22 is the same as that of the high-stage expansion valve 13, and its operation is controlled by a control signal output from the control device 40.

The refrigerant inlet of the indoor evaporator 23 is connected to the outlet of the cooling expansion valve 22. The indoor evaporator 23 is located in the case 31 of the air conditioning unit 30 upstream of the air flow of the indoor condenser 12. The indoor evaporator 23 is a heat exchanger that functions as an evaporator that cools the air by evaporating the refrigerant that circulates in the cooling operation mode, the dehumidifying and heating operation mode, and the like to exert a heat absorbing action.

The inlet of the accumulator 24 is connected to the outlet of the indoor evaporator 23. The accumulator 24 is a low-pressure side gas-liquid separator that separates the gas-liquid refrigerant flowing into the accumulator 24 and stores excess refrigerant. Furthermore, the suction port 11 a of the compressor 11 is connected to the gas phase refrigerant outlet of the accumulator 24. Accordingly, the indoor evaporator 23 is connected so that the refrigerant flows out toward the suction port 11 a of the compressor 11.

Further, an expansion valve bypass passage 25 is connected to the refrigerant outlet of the outdoor heat exchanger 20 to guide the refrigerant flowing out of the outdoor heat exchanger 20 to the inlet of the accumulator 24 by bypassing the cooling expansion valve 22 and the indoor evaporator 23. Has been. A bypass passage opening / closing valve 27 is disposed in the expansion valve bypass passage 25.

The bypass passage opening / closing valve 27 is an electromagnetic valve that opens and closes the expansion valve bypass passage 25, and its opening / closing operation is controlled by a control voltage output from the control device 40. The pressure loss that occurs when the refrigerant passes through the bypass passage opening / closing valve 27 is extremely smaller than the pressure loss that occurs when the refrigerant passes through the cooling expansion valve 22.

Therefore, the refrigerant flowing out of the outdoor heat exchanger 20 flows into the accumulator 24 via the expansion valve bypass passage 25 when the bypass passage opening / closing valve 27 is open. At this time, the throttle opening degree of the cooling expansion valve 22 may be fully closed.

Further, when the bypass passage opening / closing valve 27 is closed, it flows into the indoor evaporator 23 via the cooling expansion valve 22. Thereby, the bypass passage opening / closing valve 27 can switch the refrigerant circuit of the heat pump cycle 10. Therefore, the bypass passage opening / closing valve 27 of this embodiment forms a refrigerant circuit switching unit together with the integrated valve 14.

Next, the air conditioning unit 30 will be described. The air conditioning unit 30 is located inside the instrument panel (instrument panel) at the foremost part of the vehicle interior, and forms an outer shell of the air conditioning unit 30 and also forms an air passage for air blown into the vehicle interior in the interior. A case 31 is provided. And the air blower 32, the above-mentioned indoor condenser 12, the indoor evaporator 23, etc. are accommodated in this air passage.

The inside / outside air switching device 33 for switching and introducing vehicle interior air (inside air) and outside air is located at the most upstream part of the air flow of the case 31. The inside / outside air switching device 33 continuously adjusts the opening area of the inside air introduction port for introducing the inside air into the case 31 and the outside air introduction port for introducing the outside air by the inside / outside air switching door. The air volume ratio with the air volume is continuously changed.

A blower 32 that blows air sucked through the inside / outside air switching device 33 toward the passenger compartment is located downstream of the air flow of the inside / outside air switching device 33. The blower 32 is an electric blower that drives a centrifugal multiblade fan (sirocco fan) with an electric motor, and the number of rotations (the amount of blown air) is controlled by a control voltage output from the control device 40.

The indoor evaporator 23 and the indoor condenser 12 are arranged in the order of the indoor evaporator 23 and the indoor condenser 12 in the air flow direction downstream of the air flow of the blower 32. In other words, the indoor evaporator 23 is located upstream of the air flow of the indoor condenser 12.

In the case 31, there is provided a bypass passage 35 through which the air after passing through the indoor evaporator 23 flows around the indoor condenser 12. Further, an air mix door 34 is located in the case 31 on the downstream side of the air flow of the indoor evaporator 23 and upstream of the air flow of the indoor condenser 12.

The air mix door 34 of this embodiment adjusts the air volume ratio between the air volume passing through the indoor condenser 12 and the air volume passing through the bypass passage 35 among the air after passing through the indoor evaporator 23. It is a flow rate adjusting unit that adjusts the flow rate (air volume) of the air flowing into the indoor condenser 12. The air mix door 34 adjusts the heat exchange capability of the indoor condenser 12.

Further, downstream of the air flow of the indoor condenser 12 and the bypass passage 35, the air that is heated by exchanging heat with the refrigerant in the indoor condenser 12 and the air that is not heated through the bypass passage 35 merge. A space 36 is provided.

Therefore, the air mix door 34 adjusts the air volume ratio between the air volume that passes through the indoor condenser 12 and the air volume that passes through the bypass passage 35, thereby adjusting the temperature of the air in the merging space 36. The air mix door 34 is driven by a servo motor (not shown) whose operation is controlled by a control signal output from the control device 40.

The most downstream part of the air flow of the case 31 has an opening hole for blowing out the air merged in the merge space 36 into the vehicle interior that is the space to be cooled. Specifically, as this opening hole, a defroster opening hole 37a that blows conditioned air toward the inner side surface of the vehicle front window glass, a face opening hole 37b that blows conditioned air toward the upper body of the passenger in the vehicle interior, and the feet of the passenger The foot opening hole 37c which blows air-conditioning wind toward is provided.

Further, on the upstream side of the air flow of the defroster opening hole 37a, the face opening hole 37b, and the foot opening hole 37c, the defroster door 38a for adjusting the opening area of the defroster opening hole 37a and the face for adjusting the opening area of the face opening hole 37b, respectively. A foot door 38c for adjusting the opening area of the door 38b and the foot opening hole 37c is located.

The defroster door 38a, the face door 38b, and the foot door 38c constitute an air outlet mode switching unit that opens and closes the respective opening holes 37a to 37c and switches the air outlet mode. It is driven by a servo motor (not shown) whose operation is controlled by a control signal output from the control device 40.

In addition, the air flow downstream side of the defroster opening hole 37a, the face opening hole 37b, and the foot opening hole 37c is respectively connected to a face air outlet, a foot air outlet, and a defroster air outlet provided in the vehicle interior via ducts that form air passages. Connected to the exit.

Note that the outlet mode includes a face mode, a bi-level mode, a foot mode, and the like. In the face mode, the face opening hole 37b is fully opened, and air is blown out from the face outlet toward the upper body of the passenger in the passenger compartment. In the bi-level mode, both the face opening hole 37b and the foot opening hole 37c are opened, and air is blown out toward the upper body and the feet of the passengers in the passenger compartment. In the foot mode, the foot opening hole 37c is fully opened and the defroster opening hole 37a is opened by a small opening, and air is mainly blown out from the foot outlet.

Next, the electric control unit of this embodiment will be described. The control device 40 is composed of a well-known microcomputer including a CPU, a ROM, a RAM and the like and its peripheral circuits. The control device 40 performs various calculations and processes based on the air conditioning control program stored in the ROM, and controls the operation of various air conditioning control devices connected to the output side. The various air conditioning control devices are, for example, the compressor 11, the integrated valve 14, the bypass passage opening / closing valve 27, and the blower 32.

Further, on the input side of the control device 40, an inside air sensor, an outside air sensor, a solar radiation sensor, an evaporator temperature sensor, a blown air temperature sensor, a discharge pressure sensor, a discharge temperature sensor, a condenser temperature sensor, a suction pressure sensor, and a suction temperature sensor Various air conditioning control sensor groups 41 such as liquid phase refrigerant sensors are connected. The inside air sensor detects the vehicle interior temperature. The outside air sensor detects the outside air temperature. The solar radiation sensor detects the amount of solar radiation in the passenger compartment. The evaporator temperature sensor detects the temperature of the air blown from the indoor evaporator 23 (evaporator temperature). The blown air temperature sensor detects an actual blown air temperature that is the temperature of the air blown into the vehicle interior from the blower outlet. The discharge pressure sensor detects the pressure of the high-pressure refrigerant discharged from the compressor 11. The discharge temperature sensor detects the temperature of the high-pressure refrigerant. The condenser temperature sensor detects the temperature of the refrigerant that has flowed out of the indoor condenser 12. The suction pressure sensor detects the pressure of the low-pressure refrigerant sucked from the suction port 11 a of the compressor 11. The suction temperature sensor detects the temperature of the low-pressure refrigerant. The liquid phase refrigerant sensor detects whether or not there is a liquid phase refrigerant equal to or greater than a threshold value in the gas phase refrigerant passage 142b.

Further, an operation panel (not shown) arranged near the instrument panel in front of the vehicle interior is connected to the input side of the control device 40, and an operation signal is input from an air conditioning operation switch group 42 provided on the operation panel. The Specifically, the air conditioning operation switch group 42 includes an operation switch of the vehicle air conditioner 1, a vehicle interior temperature setting switch for setting the vehicle interior temperature, an air flow setting switch for setting the air flow into the vehicle interior, and a cooling operation mode. And a mode selection switch for selecting the heating operation mode.

In addition, although the control part which controls the operation | movement of the various air-conditioning control apparatus connected to the output side is integrally comprised, the control apparatus 40 is comprised (hardware and software) which controls the operation | movement of each control object apparatus. ) Constitutes a control unit that controls the operation of each control target device.

For example, in this embodiment, the configuration (hardware and software) for controlling the operation of the electric motor of the compressor 11 constitutes the discharge capacity control unit, and the configuration for controlling the operation of the integrated valve 14 and the bypass passage opening / closing valve 27 ( Hardware and software) constitute the refrigerant circuit control unit. The discharge capacity control unit, the refrigerant circuit control unit, and the like may be configured as a separate control device from the control device 40.

Next, the operation of the vehicle air conditioner 1 of the present embodiment having the above configuration will be described. As described above, the vehicle air conditioner 1 of the present embodiment can be switched to the cooling operation mode for cooling the vehicle interior or the heating operation mode for heating the vehicle interior. In the vehicle air conditioner 1 of the present embodiment, in order to prevent the liquid refrigerant from flowing into the intermediate pressure port 11b of the compressor 11, the liquid refrigerant inflow prevention process is executed. Hereinafter, the operation in each operation mode and the liquid-phase refrigerant inflow prevention process will be described.

(A) Air-cooling operation mode The air-cooling operation mode is started when the air-conditioning operation switch group 42 is turned on (ON) and the air-conditioning operation mode is selected by the mode selection switch. In the cooling operation mode, the control device 40 fully opens the high stage side expansion valve 13, sets the solenoid 16 of the integrated valve 14 to the energized state, sets the cooling expansion valve 22 to a throttled state that exerts a pressure reducing action, and further bypasses. The passage opening / closing valve 27 is closed.

As a result, in the integrated valve 14, as shown in FIG. 5, the first bypass valve 15 opens the first liquid-phase refrigerant passage 141d, and the gas-phase side valve body 18 closes the gas-phase refrigerant passage 142b. The cycle 10 is switched to the refrigerant circuit through which the refrigerant flows as shown by the solid arrows in FIG.

With this refrigerant circuit configuration, the control device 40 reads the detection signal of the air conditioning control sensor group 41 and the operation signal of the air conditioning operation switch group 42 described above. And the target blowing temperature TAO which is the target temperature of the air which blows off into a vehicle interior is calculated based on the value of a detection signal and an operation signal. Furthermore, based on the calculated target blowing temperature TAO and the detection signal of the sensor group, the operating states of various air conditioning control devices connected to the output side of the control device 40 are determined.

For example, the refrigerant discharge capacity of the compressor 11, that is, the control signal output to the electric motor of the compressor 11 is determined as follows. First, the target evaporator outlet temperature TEO of the indoor evaporator 23 is determined based on the target outlet temperature TAO with reference to a control map stored in the control device 40 in advance.

And based on the deviation of this target evaporator blowing temperature TEO and the blowing air temperature from the indoor evaporator 23 detected by the evaporator temperature sensor, the blowing air temperature from the indoor evaporator 23 is determined using a feedback control method. A control signal output to the electric motor of the compressor 11 is determined so as to approach the target evaporator outlet temperature TEO.

Further, the control signal output to the cooling expansion valve 22 causes the supercooling degree of the refrigerant flowing into the cooling expansion valve 22 to approach a target supercooling degree that has been determined in advance so that the COP approaches a substantially maximum value. To be determined. In addition, the control signal output to the servo motor of the air mix door 34 indicates that the air mix door 34 closes the air passage of the indoor condenser 12 and the total air flow after passing through the indoor evaporator 23 passes through the bypass passage 35. To be decided.

Then, the control signals determined as described above are output to various air conditioning control devices. Thereafter, until the operation of the vehicle air conditioner is requested to be stopped by the operation switch of the air conditioning operation switch group 42, the above-described detection signal and operation signal are read, the target blowing temperature TAO is calculated, and various air conditionings are performed every predetermined control cycle. Control routines such as determining the operating state of the control device, outputting the control voltage and the control signal are repeated. Such a control routine is repeated in the other operation modes.

Therefore, in the heat pump cycle 10 in the cooling operation mode, the high-pressure refrigerant discharged from the discharge port 11 c of the compressor 11 flows into the indoor condenser 12. At this time, since the air mix door 34 closes the air passage of the indoor condenser 12, the refrigerant flowing into the indoor condenser 12 flows out from the indoor condenser 12 without radiating heat to the air.

Since the high-stage side expansion valve 13 is fully opened, the refrigerant that has flowed out from the indoor condenser 12 flows out with almost no pressure reduction at the high-stage side expansion valve 13, and the refrigerant inlet 141 a of the integrated valve 14. Flows into the gas-liquid separation space 141b.

Since the refrigerant flowing into the integrated valve 14 is in a superheated gas phase, the gas-liquid refrigerant is not separated in the gas-liquid separation space 141b of the integrated valve 14, and the gas-phase refrigerant is in the first liquid phase. It flows into the refrigerant passage 141d. Furthermore, since the first bypass valve 15 opens the first liquid phase refrigerant passage 141d, the gas phase refrigerant flowing into the first liquid phase refrigerant passage 141d is not decompressed by the throttle 17 and is discharged from the liquid phase refrigerant outlet. 141e flows out.

That is, the refrigerant flowing into the integrated valve 14 flows out from the liquid-phase refrigerant outlet 141e with almost no pressure loss. At this time, the refrigerant pressure on the liquid-phase refrigerant outlet 141e side is guided to the back pressure chamber 142e through the pressure introduction passage 19, so that the gas-phase side valve element 18 closes the gas-phase refrigerant passage 142b. Therefore, the refrigerant does not flow out from the gas-phase refrigerant outlet 142a.

The gas-phase refrigerant that has flowed out from the liquid-phase refrigerant outlet 141e of the integrated valve 14 flows into the outdoor heat exchanger 20. The refrigerant flowing into the outdoor heat exchanger 20 exchanges heat with the outside air blown from the blower fan 21 to radiate heat. The refrigerant flowing out of the outdoor heat exchanger 20 is isoenthalpy until it flows into the cooling expansion valve 22 in the throttled state and becomes a low-pressure refrigerant because the bypass passage opening / closing valve 27 is closed. Inflated to a reduced pressure.

And the low-pressure refrigerant decompressed by the cooling expansion valve 22 flows into the indoor evaporator 23 and absorbs heat from the air blown from the blower 32 to evaporate. Thereby, air is cooled.

The refrigerant that has flowed out of the indoor evaporator 23 flows into the accumulator 24 and is separated into gas and liquid. The separated gas-phase refrigerant is sucked from the suction port 11a of the compressor 11, flows through the low-stage compression mechanism and the high-stage compression mechanism in this order, and is compressed again. On the other hand, the separated liquid-phase refrigerant is stored in the accumulator 24 as surplus refrigerant that is not necessary for exhibiting the refrigerating capacity required for the cycle.

As described above, in the cooling operation mode, since the air passage of the indoor condenser 12 is blocked by the air mix door 34, the air cooled by the indoor evaporator 23 can be blown out into the vehicle interior. Thereby, cooling of a vehicle interior is realizable.

(B) Heating operation mode Next, heating operation mode is demonstrated. As described above, in the heat pump cycle 10 of the present embodiment, the first heating operation mode and the second heating operation mode can be executed as the heating operation mode. First, the heating operation mode is started when the heating operation mode is selected by the mode selection switch while the operation switch of the air conditioning operation switch group 42 is turned on (ON).

When the heating operation mode is started, the control device 40 reads the detection signal of the sensor group 41 for air conditioning control and the operation signal of the air conditioning operation switch group 42, and the refrigerant discharge capacity of the compressor 11 (the rotation of the compressor 11). Number).

(B) -1: First Heating Operation Mode First, the first heating operation mode will be described. When the first heating operation mode is executed, the control device 40 sets the high stage side expansion valve 13 to the throttle state, sets the solenoid 16 of the integrated valve 14 to the non-energized state, sets the cooling expansion valve 22 to the fully closed state, Further, the bypass passage opening / closing valve 27 is opened.

As a result, in the integrated valve 14, as shown in FIG. 4, the first bypass valve 15 closes the first liquid-phase refrigerant passage 141d and the gas-phase side valve element 18 opens the gas-phase refrigerant passage 142b. The cycle 10 is switched to the refrigerant flow path through which the refrigerant flows as shown by the solid arrows in FIG.

That is, in the first heating operation mode, the gas-phase refrigerant separated in the gas-liquid separation space 141b flows into the intermediate pressure port 11b of the compressor 11, and a so-called gas injection operation (GI operation) is performed.

In this refrigerant flow path configuration (cycle configuration), the control device 40 reads the detection signal of the air conditioning control sensor group 41 and the operation signal of the air conditioning operation switch group 42 in the same manner as in the cooling operation mode, and the target blowout temperature TAO and Based on the detection signal of the sensor group, the operating states of various air conditioning control devices connected to the output side of the control device 40 are determined.

In the first heating operation mode, the control signal output to the high stage expansion valve 13 is determined so that the refrigerant pressure in the indoor condenser 12 becomes a predetermined target high pressure. Alternatively, the control signal is determined so that the degree of supercooling of the refrigerant flowing out of the indoor condenser 12 becomes a predetermined target degree of supercooling. Further, the control signal output to the servo motor of the air mix door 34 is such that the air mix door 34 closes the bypass passage 35 and the total air flow after passing through the indoor evaporator 23 passes through the indoor condenser 12. It is determined.

Therefore, in the heat pump cycle 10 in the heating operation mode, the high-pressure refrigerant discharged from the discharge port 11 c of the compressor 11 flows into the indoor condenser 12. The refrigerant flowing into the indoor condenser 12 exchanges heat with the air blown from the blower 32 and passed through the indoor evaporator 23 to dissipate heat. Thereby, air is heated.

The refrigerant that has flowed out of the indoor condenser 12 is decompressed and expanded in an enthalpy manner until it becomes an intermediate-pressure refrigerant by the high-stage expansion valve 13 that is in a throttled state. Then, the intermediate pressure refrigerant decompressed by the high-stage side expansion valve 13 flows into the gas-liquid separation space 141b from the refrigerant inlet 141a of the integrated valve 14 and is separated into gas and liquid.

The liquid refrigerant separated in the gas-liquid separation space 141b flows into the first liquid refrigerant passage 141d. Since the first bypass valve 15 closes the first liquid phase refrigerant passage 141d, the liquid phase refrigerant flowing into the first liquid phase refrigerant passage 141d is decompressed and expanded in an enthalpy manner until it becomes a low pressure refrigerant at the throttle 17. And flows out from the liquid-phase refrigerant outlet 141e.

At this time, the refrigerant pressure on the liquid-phase refrigerant outlet 141e side after being depressurized by the throttle 17 is guided to the back pressure chamber 142e via the pressure introduction passage 19, so that the gas-phase side valve element 18 is replaced with the gas-phase refrigerant. Open the passage 142b. Therefore, the gas-phase refrigerant separated in the gas-liquid separation space 141 b flows out from the gas-phase refrigerant outlet 142 a of the integrated valve 14 and flows into the intermediate pressure port 11 b side of the compressor 11.

The intermediate-pressure gas-phase refrigerant that has flowed into the intermediate-pressure port 11b merges with the refrigerant discharged from the low-stage compression mechanism and is sucked into the high-stage compression mechanism. On the other hand, the refrigerant that has flowed out of the liquid-phase refrigerant outlet 141e of the integrated valve 14 flows into the outdoor heat exchanger 20 and exchanges heat with the outside air blown from the blower fan 21 to absorb heat.

The refrigerant flowing out of the outdoor heat exchanger 20 flows into the accumulator 24 via the expansion valve bypass passage 25 and is separated into gas and liquid because the bypass passage opening / closing valve 27 is in the open state. The separated gas-phase refrigerant is sucked from the suction port 11a of the compressor 11 and compressed again. On the other hand, the separated liquid-phase refrigerant is stored in the accumulator 24 as surplus refrigerant that is not necessary for exhibiting the refrigerating capacity required for the cycle.

As described above, in the heating operation mode, the heat of the refrigerant discharged from the compressor 11 by the indoor condenser 12 can be radiated to the air, and the heated air can be blown into the vehicle interior. Thereby, heating of a vehicle interior is realizable.

Further, in the heating operation mode, the low-pressure refrigerant decompressed by the throttle 17 is sucked from the suction port 11a of the compressor 11, and the intermediate-pressure refrigerant decompressed by the high stage side expansion valve 13 is caused to flow into the intermediate pressure port 11b. Thus, a gas injection cycle (economizer-type refrigeration cycle) that joins with the refrigerant in the pressure increasing process can be configured.

This makes it possible to cause the high-stage compression mechanism to suck the refrigerant mixture having a low temperature, and to improve the compression efficiency of the high-stage compression mechanism. Furthermore, the compression efficiency of both compression mechanisms can be improved by reducing the pressure difference between the suction refrigerant pressure and the discharge refrigerant pressure in both the low-stage compression mechanism and the high-stage compression mechanism. As a result, the COP of the heat pump cycle 10 as a whole can be improved.

(B) -2: Second Heating Operation Mode Next, the second heating operation mode will be described. When the second heating operation mode is executed, the control device 40 sets the high stage side expansion valve 13 to the throttle state, sets the solenoid 16 of the integrated valve 14 to the energized state, sets the cooling expansion valve 22 to the fully closed state, Then, the bypass passage opening / closing valve 27 is opened. Thereby, in the integrated valve 14, as in the cooling operation mode, the state shown in FIG. 5 is established, and the heat pump cycle 10 is switched to the refrigerant flow path through which the refrigerant flows as shown by the solid line arrows in FIG.

That is, in the second heating operation mode, the gas-phase refrigerant passage 142b is closed by the gas-phase side valve body 18, and the gas-phase refrigerant separated in the gas-liquid separation space 141b enters the intermediate pressure port 11b of the compressor 11. Since it does not flow, so-called normal heat pump operation (normal HP operation) is performed.

In the second heating operation mode, the control signal output to the high stage side expansion valve 13 is determined so that the refrigerant pressure in the indoor condenser 12 becomes a predetermined target high pressure. Alternatively, the control signal is determined so that the degree of supercooling of the refrigerant flowing out of the indoor condenser 12 becomes a predetermined target degree of supercooling. Further, the control signal output to the servo motor of the air mix door 34 is such that the air mix door 34 closes the bypass passage 35 and the total air flow after passing through the indoor evaporator 23 passes through the indoor condenser 12. It is determined.

Accordingly, in the heat pump cycle 10 in the second heating operation mode, the high-pressure refrigerant discharged from the discharge port 11c of the compressor 11 flows into the indoor condenser 12 and exchanges heat with air as in the first heating operation mode. To dissipate heat. Thereby, air is heated.

The refrigerant flowing out of the indoor condenser 12 is decompressed and expanded in an enthalpy manner until it becomes a low-pressure refrigerant in the throttled high-stage expansion valve 13 and flows into the gas-liquid separation space 141b of the integrated valve 14. To do. The refrigerant that has flowed into the gas-liquid separation space 141b does not flow out of the gas-phase refrigerant outlet 142a and flows out of the liquid-phase refrigerant outlet 141e without being decompressed, as in the cooling operation mode.

The low-pressure refrigerant that has flowed out of the liquid-phase refrigerant outlet 141e flows into the outdoor heat exchanger 20, exchanges heat with the outside air blown from the blower fan 21, and absorbs heat. The refrigerant flowing out of the outdoor heat exchanger 20 flows into the accumulator 24 via the expansion valve bypass passage 25 and is separated into gas and liquid because the bypass passage opening / closing valve 27 is in the open state. The separated gas-phase refrigerant is sucked from the suction port 11a of the compressor 11.

As described above, in the second heating operation mode, the heat of the refrigerant discharged from the compressor 11 by the indoor condenser 12 can be radiated to the air, and the heated air can be blown into the vehicle interior. Thereby, heating of a vehicle interior is realizable.

(C) Liquid Phase Refrigerant Inflow Prevention Process By the way, in the first heating operation mode, the first bypass valve 15 closes the first liquid phase refrigerant passage 141d, and the gas phase side valve element 18 opens the gas phase refrigerant passage 142b. It has become. Therefore, as described above, in the transient operation region where the rotation speed of the compressor 11 suddenly increases, the balance between the amount of refrigerant flowing through the throttle 17 and the amount of refrigerant flowing into the gas-liquid separation space 141b is temporarily. The liquid-phase refrigerant accumulates in the gas-liquid separation space 141b. As a result, the refrigerant containing the liquid-phase refrigerant accumulated in the gas-liquid separation space 141 b flows into the gas-phase refrigerant passage 142 b and further flows into the intermediate pressure port 11 b of the compressor 11.

Therefore, in this embodiment, in order to prevent the liquid refrigerant from flowing into the intermediate pressure port 11b of the compressor 11, the liquid refrigerant inflow prevention process shown in FIG. 8 is executed. This liquid phase refrigerant inflow prevention process is started when the operation switch of the air conditioning operation switch group 42 is turned on.

As shown in FIG. 8, first, it is determined whether or not the current operation mode is the first heating operation mode (ie, gas injection operation) (S10).

And when it determines with it being 1st heating operation mode in S10, the refrigerant | coolant containing a liquid phase refrigerant | coolant flows in into the gaseous-phase refrigerant path 142b, and also the refrigerant | coolant containing the liquid phase refrigerant | coolant is the compressor 11. The occurrence of a phenomenon that flows into the intermediate pressure port 11b (hereinafter referred to as liquid-phase refrigerant inflow) is predicted or detected (S11).

In the present embodiment, the refrigerant state determination unit (S11) determines that liquid-phase refrigerant inflow occurs when the heating load increases and the compressor 11 is accelerated.

When it is determined in S11 that liquid-phase refrigerant inflow occurs, operation is performed in the inflow suppression unit (S12) in order to suppress the flow of refrigerant flowing into the intermediate pressure port 11b via the gas-phase refrigerant passage 142b. Switch modes.

Specifically, the operation mode is switched to the second heating operation mode (that is, normal heat pump operation). In the second heating operation mode, as shown in FIG. 5, the power is supplied to the solenoid 16 and the first bypass valve 15 opens the first liquid-phase refrigerant passage 141d, whereby the refrigerant pressure on the gas-phase refrigerant passage 142b side is increased. P2 and the refrigerant pressure P3 on the liquid-phase refrigerant outlet 141e side flowing out from the first bypass valve 15 are balanced, and the gas-phase side valve body 18 closes the gas-phase refrigerant passage 142b. Therefore, the flow of the refrigerant flowing into the intermediate pressure port 11b via the gas phase refrigerant passage 142b can be suppressed.

At this stage, the rotational speed of the compressor 11 actually increases and the refrigerant flow rate increases. However, since the first liquid-phase refrigerant passage 141d is open, there is room for refrigerant toward the outdoor heat exchanger 20. It is possible to carry it all with.

After S12, in S13, it is determined whether or not the inflow of the liquid refrigerant has not occurred even if the operation mode is returned to the first heating operation mode.

Specifically, when a predetermined time (for example, 10 to 20 seconds) has elapsed after switching to the second heating operation mode in S12, the liquid refrigerant does not flow even if the operation mode is returned to the first heating operation mode. Judge that it became.

And when the determination result of S13 is YES, the operation mode is returned to the first heating operation mode (S14). That is, as shown in FIG. 4, when the power supply to the solenoid 16 is stopped and the first bypass valve 15 closes the first liquid-phase refrigerant passage 141d, the refrigerant pressure P2 on the gas-phase refrigerant passage 142b side and the throttle 17 are closed. Based on the pressure difference from the pressure P3 of the refrigerant flowing out from the gas phase, the gas phase side valve body 18 opens the gas phase refrigerant passage 142b, and the gas injection operation is performed.

In the vehicle air conditioner 1 of the present embodiment, as described above, in order to suppress the flow of the refrigerant flowing into the intermediate pressure port 11b when it is determined that the refrigerant containing the liquid phase refrigerant flows into the gas-phase refrigerant passage 142b, The inflow of the liquid phase refrigerant into the compressor 11 can be prevented, and problems due to the inflow of the liquid phase refrigerant into the compressor 11 can be prevented. Further, in a situation where it is determined that the refrigerant containing the liquid phase refrigerant does not flow into the gas phase refrigerant passage 142b, the gas injection operation can be continued to improve the cycle efficiency (COP).
(Second Embodiment)
A second embodiment will be described. This embodiment is different from the first embodiment in the determination condition of S11 of the liquid-phase refrigerant inflow prevention process (see FIG. 8). In addition, since it is the same as that of 1st Embodiment regarding others, only a different part from 1st Embodiment is demonstrated.

In the present embodiment, in S11 of the liquid-phase refrigerant inflow prevention process (see FIG. 8), when the operating condition of the vehicle air conditioner 1 is changed by the occupant and the compressor 11 is accelerated, the liquid-phase refrigerant inflow occurs. Judge that it occurs.

Specifically, for example, when the passenger operates the vehicle interior temperature setting switch of the air conditioning operation switch group 42 to increase the vehicle interior set temperature, thereby increasing the heating load and increasing the speed of the compressor 11, It is determined that phase refrigerant inflow occurs. Alternatively, when the occupant operates the air volume setting switch of the air conditioning operation switch group 42 to increase the air volume, thereby increasing the heating load and increasing the speed of the compressor 11, it is determined that liquid phase refrigerant inflow occurs. To do.

By the way, at the time of auto control in which the rotation speed of the compressor 11 is automatically controlled according to a change in the passenger compartment temperature or the like, since the fluctuation range of the rotation speed of the compressor 11 is small, liquid-phase refrigerant inflow hardly occurs.

On the other hand, when the operating condition of the vehicle air conditioner 1 is changed by the occupant and the compressor 11 is accelerated, the rotational speed fluctuation range and acceleration (acceleration speed) of the compressor 11 tend to increase. Therefore, liquid-phase refrigerant inflow tends to occur.

Therefore, according to the present embodiment, the first heating operation mode (i.e., gas injection operation) is switched to the second heating operation mode (i.e., normal heat pump operation) only under conditions where liquid-phase refrigerant inflow is likely to occur. The opportunity of gas injection operation can be increased as compared with the first embodiment.
(Third embodiment)
A third embodiment will be described. This embodiment is different from the first embodiment in the determination condition of S11 of the liquid-phase refrigerant inflow prevention process (see FIG. 8). In addition, since it is the same as that of 1st Embodiment regarding others, only a different part from 1st Embodiment is demonstrated.

In the present embodiment, in S11 of the liquid-phase refrigerant inflow prevention process (see FIG. 8), the rotational speed of the compressor 11 before the compressor 11 is accelerated and the higher stage before the compressor 11 is accelerated. Based on the opening degree of the expansion valve 13, it is determined whether or not liquid-phase refrigerant inflow occurs.

Specifically, when the compressor 11 is accelerated from an operating state where the rotation speed of the compressor 11 is low and the opening degree of the high stage side expansion valve 13 is small, the amount of refrigerant flowing into the gas-liquid separation space 141b The fluctuation range of the liquid crystal refrigerant tends to increase, and liquid-phase refrigerant inflow tends to occur.

Therefore, the rotational speed of the compressor 11 before the compressor 11 is increased is equal to or lower than the predetermined rotational speed, and the opening degree of the high stage side expansion valve 13 before the compressor 11 is increased is the predetermined opening degree. When the compressor 11 in the following operation state is accelerated, it is determined that liquid phase refrigerant inflow occurs.

Therefore, according to the present embodiment, the first heating operation mode (that is, the gas injection operation) is switched to the second heating operation mode (that is, the normal heat pump operation) only under conditions where liquid phase refrigerant inflow is likely to occur. Therefore, the opportunity of gas injection operation can be increased as compared with the first embodiment.
(Fourth embodiment)
A fourth embodiment will be described. This embodiment is different from the first embodiment in the determination condition of S11 of the liquid-phase refrigerant inflow prevention process (see FIG. 8). In addition, since it is the same as that of 1st Embodiment regarding others, only a different part from 1st Embodiment is demonstrated.

In the present embodiment, in S11 of the liquid-phase refrigerant inflow prevention process (see FIG. 8), the number of rotations of the compressor 11 before speeding up, and the high-stage side expansion valve 13 before speeding up the compressor 11 are increased. Based on the opening degree and the acceleration of the compressor 11, it is determined whether or not liquid-phase refrigerant inflow occurs.

Specifically, the acceleration of the compressor 11 can be small even when the speed of the compressor 11 in the operating state where the rotational speed of the compressor 11 is low and the opening degree of the high stage side expansion valve 13 is small is increased. For example, the amount of refrigerant flowing into the gas-liquid separation space 141b gradually increases. Therefore, it can flow through the restrictor 17.

On the other hand, when the speed of the compressor 11 in the operating state where the rotational speed of the compressor 11 is low and the opening degree of the high stage expansion valve 13 is small is increased, the gas-liquid separation space 141b is increased if the acceleration of the compressor 11 is large. The amount of refrigerant flowing into the tank increases rapidly. Therefore, it becomes difficult to flow completely through the throttle 17, and the liquid-phase refrigerant accumulates in the gas-liquid separation space 141b.

Therefore, an operating state in which the rotation speed of the compressor 11 before the speed increase is equal to or less than the predetermined rotation speed and the opening degree of the high stage side expansion valve 13 before the speed increase of the compressor 11 is equal to or less than the predetermined opening degree. In the case where the compressor 11 is accelerated, and the acceleration of the compressor 11 is equal to or higher than a predetermined value, it is determined that liquid-phase refrigerant inflow occurs.

Therefore, according to the present embodiment, the first heating operation mode (that is, the gas injection operation) is switched to the second heating operation mode (that is, the normal heat pump operation) only under conditions where liquid phase refrigerant inflow is likely to occur. Therefore, the opportunity of gas injection operation can be increased as compared with the first embodiment.
(Fifth embodiment)
A fifth embodiment will be described. This embodiment is different from the first embodiment in the determination condition of S11 of the liquid-phase refrigerant inflow prevention process (see FIG. 8). In addition, since it is the same as that of 1st Embodiment regarding others, only a different part from 1st Embodiment is demonstrated.

In this embodiment, in S11 of the liquid-phase refrigerant inflow prevention process (see FIG. 8), it is determined whether or not liquid-phase refrigerant inflow occurs based on the speed increase amount of the compressor 11. The speed increase amount of the compressor 11 is the difference between the target speed of the compressor 11 after the speed increase and the speed of the compressor 11 before the speed increase, or the compressor after the speed increase. 11 is a ratio of the target rotational speed of 11 and the rotational speed of the compressor 11 before being increased.

Specifically, when the amount of acceleration of the compressor 11 is large, that is, when the amount of change in the amount of refrigerant flowing into the gas-liquid separation space 141b is large, it becomes difficult to flow through the throttle 17, Liquid phase refrigerant accumulates in the liquid separation space 141b. Therefore, when the speed increase amount of the compressor 11 is equal to or greater than a predetermined amount, it is determined that liquid phase refrigerant inflow occurs.

Therefore, according to the present embodiment, the first heating operation mode (i.e., gas injection operation) is switched to the second heating operation mode (i.e., normal heat pump operation) only under conditions where liquid-phase refrigerant inflow is likely to occur. The opportunity of gas injection operation can be increased as compared with the first embodiment.

Note that the estimated temperature of the air blown into the passenger compartment from the outlet (corresponding to the estimated temperature after heat exchange of the heat exchange target fluid of the present disclosure) and the target outlet temperature TAO (after heat exchange of the heat exchange target fluid of the present disclosure) The target rotational speed of the compressor 11 after the speed of the compressor 11 is increased is calculated based on the difference from the target temperature. Based on the calculated target rotational speed and the rotational speed of the compressor 11 before the compressor 11 is accelerated, the speed increase amount of the compressor 11 can be calculated. Here, based on the pressure and temperature of the high-pressure refrigerant discharged from the compressor 11, the temperature of the air blown out from the outlet into the vehicle compartment can be estimated.

Further, the target rotational speed of the compressor 11 after being increased based on the difference between the actual blown air temperature and the target blown temperature TAO is calculated. The speed increase amount of the compressor 11 can be calculated based on the calculated target speed and the speed of the compressor 11 before the speed increase.
(Sixth embodiment)
A sixth embodiment will be described. This embodiment is different from the first embodiment in the determination condition of S11 of the liquid-phase refrigerant inflow prevention process (see FIG. 8). In addition, since it is the same as that of 1st Embodiment regarding others, only a different part from 1st Embodiment is demonstrated.

In the present embodiment, in S11 of the liquid-phase refrigerant inflow prevention process (see FIG. 8), it is determined whether or not liquid-phase refrigerant inflow occurs based on the pressure of the intermediate-pressure refrigerant.

Specifically, when the pressure of the intermediate pressure refrigerant is low, the differential pressure across the throttle 17 becomes small, so the amount of refrigerant flowing through the throttle 17 is small, and liquid-phase refrigerant inflow tends to occur.

Therefore, it is determined that liquid-phase refrigerant inflow occurs when the pressure of the intermediate pressure refrigerant is equal to or lower than a predetermined pressure. Note that the predetermined pressure as the threshold value may have a positive correlation with the outside air temperature.

Therefore, according to the present embodiment, the first heating operation mode (i.e., gas injection operation) is switched to the second heating operation mode (i.e., normal heat pump operation) only under conditions where liquid-phase refrigerant inflow is likely to occur. The opportunity of gas injection operation can be increased as compared with the first embodiment.
(Seventh embodiment)
A seventh embodiment will be described. This embodiment is different from the first embodiment in the determination condition of S11 of the liquid-phase refrigerant inflow prevention process (see FIG. 8). In addition, since it is the same as that of 1st Embodiment regarding others, only a different part from 1st Embodiment is demonstrated.

In this embodiment, in S11 of the liquid-phase refrigerant inflow prevention process (see FIG. 8), whether or not liquid-phase refrigerant inflow occurs based on the degree of superheat of the high-pressure refrigerant discharged from the discharge port 11c of the compressor 11 is determined. Judging.

Specifically, when the degree of superheat of the high-pressure refrigerant is small, the refrigerant flowing into the gas-liquid separation space 141b tends to be a refrigerant containing a large amount of liquid-phase refrigerant, so that liquid-phase refrigerant inflow tends to occur.

Therefore, when the superheat degree of the high-pressure refrigerant discharged from the discharge port 11c is equal to or lower than the predetermined superheat degree, it is determined that liquid phase refrigerant inflow occurs.

Therefore, according to the present embodiment, the first heating operation mode (that is, the gas injection operation) is switched to the second heating operation mode (that is, the normal heat pump operation) only when the liquid phase refrigerant inflow is likely to occur. Therefore, the opportunity of gas injection operation can be increased as compared with the first embodiment.

The superheat degree of the high-pressure refrigerant can be obtained from a map that defines the relationship between the pressure and temperature of the high-pressure refrigerant discharged from the compressor 11 and the superheat degree of the high-pressure refrigerant.

The degree of superheat of the high-pressure refrigerant may be obtained from a map that defines the relationship between the pressure of the high-pressure refrigerant discharged from the compressor 11 and the temperature of the high-pressure refrigerant flowing out of the indoor condenser 12 and the degree of superheat of the high-pressure refrigerant. .
(Eighth embodiment)
An eighth embodiment will be described. This embodiment is different from the first embodiment in the determination condition of S11 of the liquid-phase refrigerant inflow prevention process (see FIG. 8). In addition, since it is the same as that of 1st Embodiment regarding others, only a different part from 1st Embodiment is demonstrated.

In this embodiment, in S11 of the liquid-phase refrigerant inflow prevention process (see FIG. 8), whether or not the liquid-phase refrigerant inflow occurs based on the degree of superheat of the low-pressure refrigerant sucked from the suction port 11a of the compressor 11 is determined. Judging.

Specifically, when the degree of superheat of the low-pressure refrigerant is large, the amount of refrigerant flowing through the throttle 17 is small, and liquid-phase refrigerant inflow is likely to occur.

Therefore, when the superheat degree of the low-pressure refrigerant sucked from the suction port 11a is equal to or higher than the predetermined superheat degree, it is determined that the liquid-phase refrigerant inflow occurs.

The degree of superheat of the low-pressure refrigerant sucked from the suction port 11a can be obtained based on values detected by the suction pressure sensor and the suction temperature sensor. Further, the suction pressure sensor and the suction temperature sensor are arranged in a path for guiding the refrigerant from the outdoor heat exchanger 20 to the suction port 11a.
(Ninth embodiment)
A ninth embodiment will be described. This embodiment is different from the first embodiment in the configuration of the integrated valve 14 and the determination condition in S11 of the liquid-phase refrigerant inflow prevention process (see FIG. 8). In addition, since it is the same as that of 1st Embodiment regarding others, only a different part from 1st Embodiment is demonstrated.

As shown in FIG. 9, the integrated valve 14 includes a sensor mounting body 143 for mounting a liquid phase refrigerant sensor 41 a included in the sensor group 41.

The sensor mounting body 143 includes a gas phase refrigerant passage 143a communicating with the gas phase refrigerant passage 142b of the upper body 142, and is located on the gas phase refrigerant outlet 142a side of the upper body 142.

The liquid-phase refrigerant sensor 41a has a different output when the gas-phase refrigerant comes into contact with the detection unit and when the liquid-phase refrigerant comes into contact. The liquid-phase refrigerant sensor 41a has a detection unit located below the gas-phase refrigerant passage 143a, and the liquid-phase refrigerant contacts the detection unit when the gas-phase refrigerant passage 143a has a liquid-phase refrigerant having a threshold value or more.

In S11 of the liquid-phase refrigerant inflow prevention process (see FIG. 8), when the liquid-phase refrigerant sensor 41a detects a liquid-phase refrigerant that is equal to or greater than the threshold value in the gas-phase refrigerant passage 143a, it is determined that liquid-phase refrigerant inflow occurs. .

Note that, as in the first modification of the ninth embodiment shown in FIG. 10, a gas-phase refrigerant passage (bypass) is provided in the sensor mounting body 143 in parallel with the gas-phase refrigerant passage 143 a and below the gas-phase refrigerant passage 143 a. (Refrigerant passage) 143b may be provided, and the detection unit of the liquid-phase refrigerant sensor 41a may be disposed in the bypass refrigerant passage 143b.

According to this, when the liquid phase refrigerant flows into the gas phase refrigerant passage 143a, the bypass refrigerant passage 143b is quickly filled with the liquid phase refrigerant. Therefore, the presence of the liquid phase refrigerant in the gas phase refrigerant passage 143a can be detected quickly and reliably.

Further, as in the second modification of the ninth embodiment shown in FIGS. 11 and 12, the refrigerant flowing into the gas-phase refrigerant passage 143a is swirled, and the liquid film A of the liquid-phase refrigerant is formed in the vicinity of the inner wall surface. You may make it do.

According to this, as shown in FIG. 11, when the liquid phase refrigerant flowing into the gas phase refrigerant passage 143a is small, the detection part of the liquid phase refrigerant sensor 41a is not wrapped in the liquid film A. On the other hand, as shown in FIG. 12, when there is a large amount of liquid phase refrigerant flowing into the gas phase refrigerant passage 143a, the detection part of the liquid phase refrigerant sensor 41a is enveloped in the liquid film A. Therefore, the presence of the liquid phase refrigerant in the gas phase refrigerant passage 143a can be detected quickly and reliably.

In addition, the liquid phase refrigerant | coolant sensor 41a may use the sensor which detects that there exists a liquid phase refrigerant | coolant based on the difference in the electrostatic capacitance of gas-liquid, for example. Alternatively, the liquid phase refrigerant sensor 41a may be a sensor similar to a hot-wire anemometer, which is detected by a difference in heat capacity, an optical sensor, or a sensor using an optical fiber. A sensor similar to a hot-wire anemometer is a sensor that utilizes the fact that the amount of heat taken away is large in the liquid phase and the amount of heat taken away is small in the gas phase.
(10th Embodiment)
A tenth embodiment will be described. In the present embodiment, the integrated valve 14 is eliminated, and the function of the integrated valve 14 is obtained by a plurality of components. In addition, since it is the same as that of 1st Embodiment regarding others, only a different part from 1st Embodiment is demonstrated.

As shown in FIG. 13, at the outlet of the high-stage expansion valve 13, a gas-liquid separation unit that separates the gas-liquid of the intermediate pressure refrigerant that flows out of the indoor condenser 12 and is decompressed by the high-stage expansion valve 13. A gas-liquid separator 50 is connected. The gas-liquid separator 50 is a centrifugal-type gas-liquid separator that separates the gas-liquid refrigerant by the action of centrifugal force.

Further, the gas-phase refrigerant outlet of the gas-liquid separator 50 is connected to the intermediate pressure port 11b of the compressor 11 through a gas-phase refrigerant passage 51 constituted by refrigerant piping. The gas-phase refrigerant passage 51 circulates the gas-phase refrigerant separated by the gas-liquid separator 50.

A gas phase refrigerant control valve 52 for opening and closing the gas phase refrigerant passage 51 is disposed in the gas phase refrigerant passage 51. The gas-phase refrigerant control valve 52 is an electromagnetic valve, and its operation is controlled by a control signal output from the control device 40.

Further, the gas phase refrigerant control valve 52 allows only the refrigerant to flow from the gas phase refrigerant outlet of the gas-liquid separator 50 to the intermediate pressure port 11 b side of the compressor 11 when the gas phase refrigerant passage 51 is opened. It also functions as a check valve. This prevents the refrigerant from flowing backward from the compressor 11 side to the gas-liquid separator 50 when the gas-phase refrigerant control valve 52 opens the gas-phase refrigerant passage 51. Further, the gas phase refrigerant control valve 52 switches the cycle configuration (refrigerant flow path) by opening and closing the gas phase refrigerant passage 51.

On the other hand, the liquid-phase refrigerant outlet of the gas-liquid separator 50 is connected to the outdoor heat exchanger 20 via a main liquid-phase refrigerant passage 53 constituted by refrigerant piping. The main liquid phase refrigerant passage 53 allows the liquid phase refrigerant separated by the gas-liquid separator 50 to flow therethrough.

The main liquid-phase refrigerant passage 53 is provided with a throttle 54 as a low-stage decompression unit that decompresses the liquid-phase refrigerant separated by the gas-liquid separator 50 until it becomes a low-pressure refrigerant. As the throttle 54, a nozzle or an orifice having a fixed throttle opening can be employed.

Furthermore, the liquid-phase refrigerant outlet of the gas-liquid separator 50 is connected to the outdoor heat exchanger 20 via a first liquid-phase refrigerant passage 55 constituted by refrigerant piping. The first liquid-phase refrigerant passage 55 is arranged in parallel with the throttle 54 and allows the liquid-phase refrigerant separated by the gas-liquid separator 50 to flow toward the outdoor heat exchanger 20 by bypassing the throttle 54.

The first liquid phase refrigerant passage 55 is provided with a first bypass valve 56 for opening and closing the first liquid phase refrigerant passage 55. The basic configuration of the first bypass valve 56 is the same as that of the gas-phase refrigerant control valve 52, and is an electromagnetic valve whose opening / closing operation is controlled by a control voltage output from the control device 40.

Next, the operation of the vehicle air conditioner 1 of the present embodiment having the above configuration will be described.

When the first heating operation mode is executed, the control device 40 sets the high stage side expansion valve 13 to the throttle state, sets the gas-phase refrigerant control valve 52 to the fully open state, sets the first bypass valve 56 to the fully closed state, and performs cooling. The expansion valve 22 is fully closed, and the bypass passage opening / closing valve 27 is opened.

As a result, the heat pump cycle 10 is switched to the refrigerant flow path through which the refrigerant flows as shown by the solid arrows in FIG. 13, and the gas-phase refrigerant separated by the gas-liquid separator 50 goes to the intermediate pressure port 11 b of the compressor 11. The gas injection operation is performed.

If it is determined in S11 of the liquid-phase refrigerant inflow prevention process (see FIG. 8) during execution of the first heating operation mode, the gas-phase refrigerant control valve 52 is fully closed in S12. State. Thereby, the flow of the refrigerant flowing into the intermediate pressure port 11 b via the gas-phase refrigerant passage 51 is suppressed, that is, the liquid-phase refrigerant is prevented from flowing into the compressor 11. As a result, it is possible to prevent problems due to the inflow of the liquid refrigerant into the compressor 11.

In this embodiment, the gas phase refrigerant control valve 52 is fully closed when it is determined that liquid phase refrigerant inflow occurs. However, when it is determined that liquid-phase refrigerant inflow occurs, the first bypass valve 56 may be opened while the gas-phase refrigerant control valve 52 is fully opened.

According to this, the opening of the first bypass valve 56 makes it easier for the refrigerant to flow toward the outdoor heat exchanger 20, and the liquid-phase refrigerant is prevented from accumulating in the gas-liquid separation space 141b. As a result, the inflow of the liquid phase refrigerant into the compressor 11 is prevented, and a problem due to the inflow of the liquid phase refrigerant into the compressor 11 is prevented.

In addition, since the gas-injection operation is continued while maintaining the gas-phase refrigerant control valve 52 in a fully opened state, cycle efficiency (COP) can be improved.
(Eleventh embodiment)
An eleventh embodiment will be described. This embodiment is different from the first embodiment in that the opening degree of the diaphragm 17 can be adjusted. In addition, since it is the same as that of 1st Embodiment regarding others, only a different part from 1st Embodiment is demonstrated.

As shown in FIG. 14, the throttle 17 as the low-stage decompression unit includes an electric actuator that includes a valve element that can change the throttle opening degree and an electric actuator that includes a stepping motor that changes the throttle opening degree of the valve element. This is a variable aperture mechanism. The operation of the diaphragm 17 is controlled by a control signal output from the control device 40.

In the above configuration, the opening degree of the throttle 17 during execution of the first heating operation mode is such that the dryness degree X of the refrigerant upstream of the throttle 17 is 0.1 or less even if the necessary circulating refrigerant flow rate changes due to cycle load fluctuations. It is set to become.

And when it is judged that liquid phase refrigerant inflow occurs in S11 of liquid phase refrigerant inflow prevention processing (refer to Drawing 8) during execution of the 1st heating operation mode, the opening of throttle 17 is increased in S12. Thereby, the refrigerant easily flows toward the outdoor heat exchanger 20, and the liquid-phase refrigerant is prevented from accumulating in the gas-liquid separation space 141b. As a result, the inflow of the liquid phase refrigerant into the compressor 11 is prevented, and a problem due to the inflow of the liquid phase refrigerant into the compressor 11 is prevented.

Further, since the gas injection operation can be continued even if the opening degree of the throttle 17 is increased, the cycle efficiency (COP) can be improved.
(Twelfth embodiment)
A twelfth embodiment will be described. This embodiment is different from the first embodiment in that a second liquid-phase refrigerant passage, a second bypass valve, and a detection unit are provided. In addition, since it is the same as that of 1st Embodiment regarding others, only a different part from 1st Embodiment is demonstrated.

15 to 18, the lower body 141 of the integrated valve 14 is formed with a second liquid phase refrigerant passage 141g in parallel with the throttle 17 and the first liquid phase refrigerant passage 141d. Then, the liquid-phase refrigerant separated in the gas-liquid separation space 141b bypasses the throttle 17 and the first liquid-phase refrigerant passage 141d, passes through the second liquid-phase refrigerant passage 141g, and goes to the liquid-phase refrigerant outlet 141e side. Distribution is possible.

In the lower body 141 of the integrated valve 14, a second bypass valve 60 that opens and closes the second liquid-phase refrigerant passage 141g is disposed.

In addition, a detection unit 61 that drives the second bypass valve 60 is disposed in a path that guides the low-pressure refrigerant from the outdoor heat exchanger 20 to the suction port 11a of the compressor 11.

The detection unit 61 includes a diaphragm 611 and a shaft 612 having one end joined to the diaphragm 611. A second bypass valve 60 is joined to the other end of the shaft 612.

The first chamber 613 formed on one side of the diaphragm 611 (the upper side in FIGS. 17 and 18) communicates with a path for guiding the refrigerant from the outdoor heat exchanger 20 to the suction port 11a of the compressor 11. For this reason, the pressure of the low-pressure refrigerant flowing through the path is equal to the pressure in the first chamber 613.

Refrigerant gas is enclosed in the second chamber 614 formed on the other side of the diaphragm 611 (the lower side of FIGS. 17 and 18). The pressure in the second chamber 614 changes according to the temperature of the low-pressure refrigerant sucked from the suction port 11a. Specifically, when the temperature of the low-pressure refrigerant increases, that is, when the degree of superheat of the low-pressure refrigerant increases, the pressure in the second chamber 614 also increases. The diaphragm 611 is displaced according to the pressure difference between the pressure in the first chamber 613 and the pressure in the second chamber 614. In other words, the diaphragm 611 is displaced according to the degree of superheat of the low-pressure refrigerant sucked from the suction port 11a. The detection unit 61 corresponds to a refrigerant state determination unit and an inflow suppression unit of the present disclosure.

In the cooling operation mode, as shown in FIG. 16, the solenoid 16 of the integrated valve 14 is energized, so the first bypass valve 15 opens the first liquid-phase refrigerant passage 141d. Further, in the state where the first liquid-phase refrigerant passage 141d is opened, the degree of superheat of the low-pressure refrigerant is low and the pressure in the second chamber 614 is also low. Therefore, the second bypass valve 60 is driven by the diaphragm 611 in the valve closing direction to close the second liquid phase refrigerant passage 141g.

When the first heating operation mode is executed, as shown in FIG. 17, the solenoid 16 of the integrated valve 14 is in a non-energized state, so the first bypass valve 15 closes the first liquid-phase refrigerant passage 141d. In a steady operation state, the temperature of the low-pressure refrigerant is low and the pressure in the second chamber 614 is also low. Therefore, the second bypass valve 60 is driven by the diaphragm 611 in the valve closing direction to close the second liquid phase refrigerant passage 141g.

As described above, in a state where the first liquid phase refrigerant passage 141d and the second liquid phase refrigerant passage 141g are closed, the liquid phase refrigerant separated in the gas-liquid separation space 141b of the integrated valve 14 is reduced in pressure by the throttle 17. It is decompressed and expanded in an enthalpy manner until it becomes a refrigerant, and flows out from the liquid-phase refrigerant outlet 141e.

When the heating load is increased and the compressor 11 is accelerated during execution of the first heating operation mode, the amount of liquid phase refrigerant separated in the gas-liquid separation space 141b of the integrated valve 14 increases. Therefore, it becomes difficult to distribute the liquid-phase refrigerant only by the throttle 17, and the degree of superheat of the low-pressure refrigerant increases.

When the degree of superheat of the low-pressure refrigerant increases, the pressure in the second chamber 614 also increases. As shown in FIG. 18, the second bypass valve 60 is driven in the valve opening direction by the diaphragm 611, and the second liquid-phase refrigerant. Open the passage 141g.

Therefore, since the liquid-phase refrigerant separated in the gas-liquid separation space 141b flows through the throttle 17 and the second liquid-phase refrigerant passage 141g, the liquid-phase refrigerant is prevented from accumulating in the gas-liquid separation space 141b. As a result, the inflow of the liquid phase refrigerant into the compressor 11 is prevented, and a problem due to the inflow of the liquid phase refrigerant into the compressor 11 is prevented.

Further, since the gas injection operation can be continued even if the second liquid-phase refrigerant passage 141g is opened, cycle efficiency (COP) can be improved.
(13th Embodiment)
A thirteenth embodiment will be described. This embodiment is different from the first embodiment in that a gas-phase refrigerant passage opening / closing valve and a detection unit are provided. In addition, since it is the same as that of 1st Embodiment regarding others, only a different part from 1st Embodiment is demonstrated.

As shown in FIG. 19, the refrigerant passage connecting the gas-phase refrigerant outlet 142a of the integrated valve 14 and the intermediate pressure port 11b of the compressor 11 has a passage opening / closing valve (gas-phase refrigerant passage opening / closing) for opening and closing the refrigerant passage. Valve) 70 is arranged.

In addition, a detection unit 71 that drives the passage opening / closing valve 70 is disposed in a path that guides the low-pressure refrigerant from the outdoor heat exchanger 20 to the suction port 11a of the compressor 11.

The detecting unit 71 includes a diaphragm 711 and a shaft 712 having one end joined to the diaphragm 711, and a passage opening / closing valve 70 is joined to the other end of the shaft 712.

The first chamber 713 formed on one side of the diaphragm 711 (upper side in FIG. 19) communicates with a path connecting the outdoor heat exchanger 20 to the cooling expansion valve 22 and the bypass passage opening / closing valve 27. For this reason, the pressure in the first chamber 713 is equal to the pressure of the low-pressure refrigerant flowing out of the outdoor heat exchanger 20.

A refrigerant gas is sealed in the second chamber 714 formed on the other side of the diaphragm 711 (the lower side in FIG. 19). The pressure in the second chamber 714 changes according to the temperature of the low-pressure refrigerant flowing out of the outdoor heat exchanger 20. Specifically, when the temperature of the low-pressure refrigerant increases, that is, when the degree of superheat of the low-pressure refrigerant increases, the pressure in the second chamber 714 also increases. The diaphragm 711 is displaced according to the pressure difference between the pressure in the first chamber 713 and the pressure in the second chamber 714. In other words, the diaphragm 711 is displaced according to the degree of superheat of the low-pressure refrigerant flowing out from the outdoor heat exchanger 20. The detection unit 71 corresponds to the refrigerant state determination unit and the inflow suppression unit of the present disclosure.

First, in a steady operation state, the degree of superheat of the low-pressure refrigerant is low and the pressure in the second chamber 714 is also low. Therefore, the passage opening / closing valve 70 is driven by the diaphragm 711 in the valve opening direction to fully open the refrigerant passage that connects the gas-phase refrigerant outlet 142 a of the integrated valve 14 and the intermediate pressure port 11 b of the compressor 11.

When the degree of superheat of the low-pressure refrigerant increases, the pressure in the second chamber 714 also increases, and the passage opening / closing valve 70 is driven by the diaphragm 711 in the valve closing direction. Thereby, the passage opening / closing valve 70 closes the refrigerant passage connecting the gas-phase refrigerant outlet 142a of the integrated valve 14 and the intermediate pressure port 11b of the compressor 11. Therefore, the flow of the refrigerant flowing into the intermediate pressure port 11b is prevented, and problems due to the inflow of the liquid phase refrigerant into the compressor 11 are prevented.
(14th Embodiment)
A fourteenth embodiment will be described. This embodiment is different from the first embodiment in that a gas-phase refrigerant passage opening / closing valve and a detection unit are provided. In addition, since it is the same as that of 1st Embodiment regarding others, only a different part from 1st Embodiment is demonstrated.

As shown in FIG. 20, the refrigerant passage connecting the gas-phase refrigerant outlet 142a of the integrated valve 14 and the intermediate pressure port 11b of the compressor 11 has a passage opening / closing valve (gas-phase refrigerant passage opening / closing) for opening and closing the refrigerant passage. Valve) 80 is arranged.

In addition, a detection unit 81 that drives the passage opening / closing valve 80 is disposed in a path that guides the low-pressure refrigerant from the outdoor heat exchanger 20 to the suction port 11a of the compressor 11.

The detection unit 81 includes a diaphragm 811 and a shaft 812 having one end joined to the diaphragm 811, and a passage opening / closing valve 80 is joined to the other end of the shaft 812.

The first chamber 813 formed on one side of the diaphragm 811 (upper side in FIG. 20) communicates with a path connecting the accumulator 24 and the suction port 11a of the compressor 11. Therefore, the pressure in the first chamber 813 is equal to the pressure of the low-pressure refrigerant sucked from the suction port 11a.

Refrigerant gas is enclosed in the second chamber 814 formed on the other side of the diaphragm 811 (the lower side in FIG. 20). The pressure in the second chamber 814 changes according to the temperature of the low-pressure refrigerant sucked from the suction port 11a. Specifically, when the temperature of the low-pressure refrigerant increases, that is, when the degree of superheat of the low-pressure refrigerant increases, the pressure in the second chamber 814 also increases. The diaphragm 811 is displaced according to the pressure difference between the pressure in the first chamber 813 and the pressure in the second chamber 814. In other words, the diaphragm 811 is displaced according to the degree of superheat of the low-pressure refrigerant sucked from the suction port 11a. The detection unit 81 corresponds to the refrigerant state determination unit and the inflow suppression unit of the present disclosure.

First, in a steady operation state, the degree of superheat of the low-pressure refrigerant is low and the pressure in the second chamber 814 is also low. Therefore, the gas-phase refrigerant passage opening / closing valve 80 is driven by the diaphragm 811 in the valve opening direction to open a refrigerant passage connecting the gas-phase refrigerant outlet 142a of the integrated valve 14 and the intermediate pressure port 11b of the compressor 11. Yes.

When the degree of superheat of the low-pressure refrigerant increases, the pressure in the second chamber 814 also increases, and the gas-phase refrigerant passage opening / closing valve 80 is driven by the diaphragm 811 in the valve closing direction so that the gas-phase refrigerant outlet 142a of the integrated valve 14 And the refrigerant passage connecting the intermediate pressure port 11b of the compressor 11 is closed. Therefore, the flow of the refrigerant flowing into the intermediate pressure port 11b is prevented, and problems due to the inflow of the liquid phase refrigerant into the compressor 11 are prevented.

In the present embodiment, when the superheat degree of the low-pressure refrigerant becomes high during execution of the first heating operation mode, the refrigerant passage that connects the gas-phase refrigerant outlet 142a of the integrated valve 14 and the intermediate pressure port 11b of the compressor 11 is closed. I did it. However, when the superheat degree of the low-pressure refrigerant becomes high during execution of the first heating operation mode, the flow area of the refrigerant passage that connects the gas-phase refrigerant outlet 142a of the integrated valve 14 and the intermediate pressure port 11b of the compressor 11 May be reduced. In this case, even if the liquid-phase refrigerant flows out from the gas-phase refrigerant outlet 142a, the liquid-phase refrigerant is gasified at the portion where the circulation area of the refrigerant passage is reduced. As a result, problems due to the inflow of the liquid phase refrigerant into the compressor 11 are prevented.
(Fifteenth embodiment)
A fifteenth embodiment is described. This embodiment is different from the first embodiment in that S15 is added to the liquid-phase refrigerant inflow prevention process. In addition, since it is the same as that of 1st Embodiment regarding others, only a different part from 1st Embodiment is demonstrated.

As shown in FIG. 21, after executing S12, the throttle opening of the high stage side expansion valve 13 is increased in S15 as the pressure reduction control unit.

Incidentally, when the throttle opening of the high stage side expansion valve 13 is increased in the first heating operation mode (that is, the gas injection operation), the difference between the pressure of the high-pressure refrigerant and the pressure of the intermediate-pressure refrigerant decreases, Pressure increases. On the other hand, the pressure of the low-pressure refrigerant is not substantially changed because the temperature of the outside air in contact with the outdoor heat exchanger 20 is dominant. Therefore, the pressure difference between the pressure of the intermediate pressure refrigerant and the pressure of the low pressure refrigerant can be increased. However, in actuality, since the mode is switched to the second heating operation mode in S12, the first bypass valve 15 is opened and no pressure difference is generated between the pressure of the intermediate pressure refrigerant and the pressure of the low pressure refrigerant.

S15 is intended to secure a pressure difference generated in the throttle 17 immediately after switching at the stage where the operation mode is returned to the first heating operation mode in S14. By executing S15, it is possible to secure the pressure difference and increase the flow rate of the refrigerant that the throttle 17 can flow. As a result, a large amount of refrigerant flowing into the gas-liquid separation space 141b can be securely flowed to the low pressure side.
(Other embodiments)
Note that the present disclosure is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist of the present disclosure.

Further, the above embodiments are not irrelevant to each other, and can be appropriately combined unless the combination is clearly impossible.

In each of the above-described embodiments, it is needless to say that elements constituting the embodiment are not necessarily essential unless explicitly stated as essential and clearly considered essential in principle. Yes.

Further, in each of the above embodiments, when numerical values such as the number, numerical value, quantity, range, etc. of the constituent elements of the embodiment are mentioned, it is clearly limited to a specific number when clearly indicated as essential and in principle. The number is not limited to the specific number except for the case.

Further, in each of the above embodiments, when referring to the shape, positional relationship, etc. of the component, etc., the shape, unless otherwise specified and in principle limited to a specific shape, positional relationship, etc. It is not limited to the positional relationship or the like.

Claims

The low-pressure refrigerant sucked from the suction port (11a) is compressed and discharged as high-pressure refrigerant from the discharge port (11c), and the intermediate-pressure port (11b) that causes the intermediate-pressure refrigerant in the cycle to flow in and merge with the refrigerant in the compression process ) Having a compressor (11),
A use-side heat exchanger (12) that heat-exchanges the heat exchange target fluid by exchanging heat between the high-pressure refrigerant discharged from the discharge port and the heat exchange target fluid;
A high-stage decompression section (13) that decompresses the high-pressure refrigerant that has flowed out of the use-side heat exchanger until the intermediate-pressure refrigerant is obtained;
A gas-liquid separator (50, 141b) that separates the gas-liquid of the intermediate-pressure refrigerant decompressed by the high-stage decompression unit;
A gas-phase refrigerant passage (51, 142b, 143a) for guiding the gas-phase refrigerant separated in the gas-liquid separator to the intermediate pressure port;
A gas phase refrigerant control valve (18, 52) for opening and closing the gas phase refrigerant passage;
A low-stage decompression section (17, 54) for decompressing the liquid-phase refrigerant separated in the gas-liquid separation section;
An evaporator (20) for evaporating the refrigerant decompressed by the low-stage decompression unit and causing the refrigerant to flow out to the suction port side as the low-pressure refrigerant;
During the gas injection operation of opening the gas-phase refrigerant control valve and allowing the intermediate-pressure refrigerant to flow into the intermediate-pressure port, it is determined whether or not refrigerant containing liquid-phase refrigerant flows into the gas-phase refrigerant passage. A refrigerant state determination unit (S11, 61, 71, 81) to perform,
Inflow suppression that suppresses the flow of the refrigerant flowing into the intermediate pressure port through the gas-phase refrigerant passage when the refrigerant state determination unit determines that the refrigerant containing the liquid-phase refrigerant flows into the gas-phase refrigerant passage. Part (S12, 61, 71, 81).
The heat pump cycle according to claim 1, wherein the refrigerant state determination unit determines that a refrigerant containing a liquid phase refrigerant flows into the gas phase refrigerant passage when the compressor is accelerated.
2. The refrigerant state determination unit according to claim 1, wherein when the operating condition is changed by an occupant and the compressor is accelerated, the refrigerant state determination unit determines that a refrigerant containing a liquid phase refrigerant flows into the gas phase refrigerant passage. Heat pump cycle.
The refrigerant state determination unit is configured to determine the gas-phase refrigerant path based on the rotation speed of the compressor before the compressor is accelerated and the opening of the high-stage decompression unit before the compressor is accelerated. The heat pump cycle according to claim 1, wherein it is determined whether or not a refrigerant containing a liquid phase refrigerant flows into the tank.
The refrigerant state determination unit is based on the rotation speed of the compressor before the compressor is accelerated, the opening degree of the high-stage decompression unit before the compressor is accelerated, and the acceleration of the compressor. The heat pump cycle according to claim 1, wherein it is determined whether or not a refrigerant containing a liquid phase refrigerant flows into the gas phase refrigerant passage.
The refrigerant state determination unit is configured such that the rotation speed of the compressor before the speed of the compressor is increased is equal to or less than a predetermined speed, and the opening degree of the high-stage decompression section before the speed of the compressor is increased. The heat pump cycle according to claim 4 or 5, wherein it is determined that a refrigerant containing a liquid phase refrigerant flows into the gas phase refrigerant passage when the opening degree is equal to or less than a predetermined opening degree.
The heat pump cycle according to claim 1, wherein the refrigerant state determination unit determines that a refrigerant containing a liquid-phase refrigerant flows into the gas-phase refrigerant passage when an acceleration amount of the compressor is a predetermined amount or more.
The speed increase amount of the compressor is the difference between the target speed of the compressor after the speed of the compressor is increased and the speed of the compressor before the speed of the compressor is increased,
The compressor after the compressor is accelerated based on the difference between the estimated temperature after heat exchange of the heat exchange target fluid and the target temperature after heat exchange of the heat exchange target fluid And calculating the speed increase amount of the compressor based on the calculated target speed and the rotation speed of the compressor before the speed of the compressor is increased,
The said refrigerant | coolant state determination part determines that the refrigerant | coolant containing a liquid phase refrigerant flows in into the said gaseous-phase refrigerant path, when the calculated acceleration amount of the said compressor is more than predetermined rotation speed. Heat pump cycle.
The heat pump cycle according to claim 1, wherein the refrigerant state determination unit determines that a refrigerant containing a liquid phase refrigerant flows into the gas phase refrigerant passage when a pressure of the intermediate pressure refrigerant is equal to or lower than a predetermined pressure.
The heat pump cycle according to claim 9, wherein the predetermined pressure has a positive correlation with an outside air temperature.
The refrigerant state determination unit determines that a refrigerant containing a liquid phase refrigerant flows into the gas-phase refrigerant passage when a superheat degree of the high-pressure refrigerant discharged from the discharge port is equal to or lower than a predetermined superheat degree. The heat pump cycle according to 1.
The refrigerant state determination unit determines that a refrigerant containing a liquid-phase refrigerant flows into the gas-phase refrigerant passage when the superheat degree of the low-pressure refrigerant sucked into the suction port is equal to or higher than a predetermined superheat degree. The heat pump cycle according to 1.
The refrigerant state determination unit
A suction pressure sensor for detecting the pressure of the low-pressure refrigerant sucked from the suction port;
A suction temperature sensor for detecting the temperature of the low-pressure refrigerant sucked from the suction port;
The heat pump cycle according to claim 12, wherein the refrigerant state determination unit calculates the degree of superheat of the low-pressure refrigerant sucked from the suction port based on values detected by the suction pressure sensor and the suction temperature sensor.
14. The heat pump cycle according to claim 13, wherein the suction pressure sensor and the suction temperature sensor are arranged in a path for guiding a refrigerant from the evaporator to the suction port.
A liquid phase refrigerant sensor (41a) for detecting whether or not there is a liquid phase refrigerant equal to or higher than a threshold in the gas phase refrigerant passage (143a);
The refrigerant state determination unit, when the liquid-phase refrigerant sensor detects that the gas-phase refrigerant passage has a liquid-phase refrigerant of a threshold value or more, the refrigerant containing the liquid-phase refrigerant in the gas-phase refrigerant passage The heat pump cycle according to claim 1, wherein the heat pump cycle is determined to flow in.
The inflow suppression unit closes the gas phase refrigerant control valve when the refrigerant state determination unit determines that a refrigerant containing a liquid phase refrigerant flows into the gas phase refrigerant passage. The heat pump cycle as described in any one.
The opening degree of the low-stage decompression unit is adjustable,
The said inflow suppression part increases the opening degree of the said low stage pressure reduction part, when the said refrigerant | coolant state judgment part judges that the refrigerant | coolant containing a liquid phase refrigerant flows in into the said gaseous-phase refrigerant path. Heat pump cycle.
A first liquid-phase refrigerant passage (55, which is arranged in parallel with the low-stage decompression section and flows the liquid-phase refrigerant separated by the gas-liquid separation section to the evaporator bypassing the low-stage decompression section. 141d),
A first bypass valve (15, 56) for opening and closing the first liquid phase refrigerant passage,
The inflow suppression unit opens the first bypass valve when the refrigerant state determination unit determines that a refrigerant containing a liquid phase refrigerant flows into the gas-phase refrigerant passage. The heat pump cycle according to one.
A first liquid-phase refrigerant passage (141d) that is arranged in parallel with the low-stage decompression section and flows the liquid-phase refrigerant separated by the gas-liquid separation section to the evaporator, bypassing the low-stage decompression section When,
A first bypass valve (15) for opening and closing the first liquid phase refrigerant passage;
A second stage disposed in parallel with the low-stage decompression section and the first liquid-phase refrigerant passage, and allows the liquid-phase refrigerant to flow to the evaporator, bypassing the low-stage decompression section and the first liquid-phase refrigerant path. A liquid phase refrigerant passage (141 g);
A second bypass valve (60) for opening and closing the second liquid phase refrigerant passage,
When the first bypass valve closes the first liquid-phase refrigerant passage, based on the pressure difference between the pressure of the refrigerant flowing out from the low-stage decompression section and the pressure of the refrigerant flowing into the gas-phase refrigerant passage. The gas-phase refrigerant control valve opens the gas-phase refrigerant passage;
When the first bypass valve opens the first liquid-phase refrigerant passage, the pressure of the refrigerant flowing into the gas-phase refrigerant passage and the pressure of the refrigerant flowing out of the first bypass valve are balanced so that the gas phase A refrigerant control valve closes the gas-phase refrigerant passage;
The said inflow suppression part (61) opens the said 2nd bypass valve, when the said refrigerant | coolant state judgment part judges that the refrigerant | coolant containing a liquid phase refrigerant flows in into the said gaseous-phase refrigerant path. Heat pump cycle.
The inflow suppression unit and the refrigerant state determination unit are configured by a detection unit (61) in which a diaphragm (611) is displaced according to the degree of superheat of the low-pressure refrigerant sucked from the suction port,
The heat pump cycle according to claim 19, wherein the second bypass valve is driven by the detection unit.
21. The heat pump cycle according to claim 20, wherein the detection unit is disposed in a path for guiding a refrigerant from the evaporator to the suction port.
The opening degree of the high-stage decompression unit is adjustable,
The pressure reduction control part (S15) which increases the opening degree of the said high pressure side pressure reduction part, when the said refrigerant | coolant state judgment part judges that the refrigerant | coolant containing a liquid phase refrigerant flows in into the said gaseous-phase refrigerant channel | path. The heat pump cycle as described in any one of thru | or 21.