JPH10220888A - Refrigerating cycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce noise upon opening a solenoid valve, in a refrigerating cycle provided with two sets of evaporators and expansion valves, which are arranged in parallel respectively. SOLUTION: In a refrigerating cycle, a compressor 1, a condenser 2, an expansion valve 41 and an evaporator 51 are provided in series, another expansion valve 42 and another evaporator 52 are provided in parallel to the expansion valve 41 and the evaporator 51 while a joining unit 53 is provided at the downstream of the evaporators 51, 52. In this case, a refrigerant flow passage at the downstream of the expansion valve 42 and the upstream side of the evaporator 52 is opened and closed by a solenoid valve 6, another refrigerant flow passage at the downstream of the evaporator 52 and the upstream of the joining unit 53 is opened and closed by another solenoid valve 7, the opening degree of the expansion valve 42 is regulated in accordance with a pressure difference between the pressure P2 of the evaporator at the downstream of the solenoid valve 6 and the saturated pressure P1 of refrigerant in accordance with a refrigerant temperature at the outlet port of the evaporator at the upstream of the second solenoid valve 7, the solenoid valve 7 is closed upon closing the solenoid valve 6 and the solenoid valve 7 is opened upon opening the solenoid valve 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigeration cycle in which an electromagnetic valve is disposed downstream of an expansion valve. For example, a refrigeration cycle evaporator is built in both the front side and the rear side in a vehicle compartment. It is suitable for use in a vehicle air conditioner or the like in which an air conditioning unit is provided.

[0002]

2. Description of the Related Art Conventionally, evaporators for cooling have been provided in air conditioning units before and after a vehicle cabin, for example, in order to independently perform air conditioning control on a front side and air conditioning control on a rear side in a vehicle interior. In addition, there has been known a refrigeration cycle for vehicle air conditioning, in which two cooling evaporators and expansion valves for reducing the pressure of refrigerant flowing into these evaporators are arranged in parallel.

In this refrigeration cycle, 2
In order to interrupt the flow of the refrigerant to the two evaporators, an electromagnetic valve for opening and closing the refrigerant flow path on the upstream side of the expansion valve is provided. However, when the flow of the liquid-phase refrigerant on the high pressure side before the pressure is reduced by the expansion valve is suddenly cut off by the solenoid valve, there is a problem that a water hammer sound is generated. In addition, when the solenoid valve that has blocked the flow of the refrigerant is opened, there is a problem that noise is generated due to the high-pressure liquid refrigerant suddenly colliding with the throttle portion of the expansion valve.

Therefore, in Japanese Patent Application Laid-Open No. Hei 7-151422, a solenoid valve is disposed downstream of an expansion valve (that is, a low-pressure side flow path through which a gas-liquid two-phase refrigerant flows) to close the solenoid valve. In order to reduce the noise of the water hammer at the time of operation and the noise at the time of opening the solenoid valve, there has been proposed one that reduces the noise.

[0005]

However, the present inventors have conducted various experimental studies on the prior art described in the above-mentioned publication, and found that when the solenoid valve was opened, noise could not be reduced for the following reasons. I understood. here,
In the prior art described in the above publication, the saturation pressure of the refrigerant at the evaporator outlet refrigerant temperature is applied to the upper side of the diaphragm of the expansion valve, and the evaporator pressure downstream of the solenoid valve is applied to the lower side of the diaphragm. Thus, the diaphragm is changed in accordance with the two pressure differences, and this change is transmitted to the valve body of the expansion valve, thereby adjusting the valve opening of the expansion valve.

When the flow of the refrigerant in one of the evaporators is stopped by closing the solenoid valve, the temperature of the evaporator rises to the ambient temperature (room temperature). Saturation pressure (for example, 0.6 MPa
Act). On the other hand, the downstream side of the solenoid valve is
The refrigerant is circulated to the other evaporator (the operation of the compressor) to reduce the pressure (for example, to about 0.3 MPa), and this pressure acts on the lower side of the diaphragm. As a result, a force in the valve opening direction acts on the valve body of the expansion valve, and the expansion valve is fully opened.

When the solenoid valve opens when the expansion valve is fully opened, a sudden pressure change occurs at the solenoid valve portion, and the pressure change is caused by the liquid refrigerant via the upstream pipe of the solenoid valve, specifically, It was found that the noise propagated to the high-pressure pipe connected to the upstream side of the expansion valve to vibrate the pipe and generate noise. In addition, it was found that a large flow rate of the refrigerant suddenly started flowing into the evaporator where the flow of the refrigerant had stopped, and a refrigerant flow noise (noise) was generated.

[0008] The present invention has been made in view of the above points,
In a refrigerating cycle in which two evaporators and an expansion valve are respectively arranged in parallel, an object is to reduce noise when the solenoid valve is opened.

[0009]

According to the first and second aspects of the present invention, a gas refrigerant discharged from a compressor (1) is condensed in a condenser (2), and the condensed gas refrigerant is condensed in the condenser (2). The expanded liquid refrigerant is decompressed and expanded by the first expansion valve (41) and the second expansion valve (42) provided in parallel, and the decompressed and expanded refrigerant is supplied to the first evaporator (51) and the second evaporator (51) provided in parallel. 2 The evaporator (52) evaporates the refrigerant and the first and second evaporators (51, 52) evaporate the refrigerant.
In the refrigerating cycle in which the refrigerant flows into the compressor (1) after being merged in 3), the refrigerant flow path between the downstream of the second expansion valve (42) and the upstream of the second evaporator (52) is separated by the first electromagnetic wave. Valve (6)
To open and close at the junction with the downstream of the second evaporator (52).
The refrigerant passage between the upstream side and the upstream side is opened and closed by a second solenoid valve (7), and the evaporator pressure (P2) downstream of the first solenoid valve (6) and the evaporation upstream of the second solenoid valve (7). When the valve opening of the second expansion valve (42) is adjusted based on the temperature of the refrigerant at the outlet of the device, and the supply of the refrigerant to the second evaporator (52) is shut off, the first solenoid valve (6) and the second The second solenoid valve (7) is closed, and when supplying the refrigerant to the second evaporator (52), the first solenoid valve (6) and the second solenoid valve (7) are opened. And

According to the above configuration, when the first solenoid valve (6) and the second solenoid valve (7) are closed, even if the refrigeration cycle is operating, the first solenoid valve (6) and the second solenoid valve (6) are closed. Valve (7)
Is cut off from the high pressure side pressure (for example, about 2.0 MPa) and the low pressure side pressure (for example, about 0.3 MPa). Therefore, between the first solenoid valve (6) and the second solenoid valve (7), the refrigerant temperature is about room temperature (for example, 20 ° C.).
To the evaporator pressure downstream of the first solenoid valve (6) (P
Since the pressure in 2) does not become low, a force in the valve closing direction acts on the expansion valve (42), and the expansion valve (42) is fully closed.

When the first solenoid valve (6) is closed, the pressure upstream of the first solenoid valve (6) is high due to the operation of the refrigeration cycle. )
When the valve is opened, the pressure fluctuates sharply at the first solenoid valve (6). Immediately after the opening, the expansion valve (42) is in a closed state. In addition to the above, it is possible to suppress the large flow of the refrigerant from flowing out abruptly, and it is possible to effectively suppress the generation of the refrigerant flow noise and the like.

The first solenoid valve (6) is provided with an expansion valve (4).
2) Since it is installed in the refrigerant flow area in the gas-liquid two-phase state on the downstream side, the water hammer noise when the solenoid valve (6) is closed can be reduced well as before.

[0013]

Embodiments of the present invention will be described below. (First Embodiment) FIG. 1 shows the overall configuration of a refrigeration cycle according to the present invention. This refrigeration cycle is a vehicle having independently controllable air conditioning units on the front seat side and the rear seat side of the vehicle. It is used for air conditioners.

The refrigeration cycle shown in FIG. 1 includes a compressor 1, which is equipped with an electromagnetic clutch for interrupting power transmission. When the electromagnetic clutch is connected, a vehicle (not shown) is provided. Power is transmitted from the engine, and the compressor 1 operates to compress the suction refrigerant and discharge it as a high-temperature and high-pressure gas refrigerant. The condenser 2 cools and condenses the gas refrigerant discharged from the compressor 1 by air cooling by a cooling fan (not shown), and the condensed liquid refrigerant flows into the liquid receiver 3. The liquid receiver 3 gas-liquid separates the condensed refrigerant flowing into the liquid receiver 3 and allows only the liquid refrigerant to flow out. Downstream of the receiver 3, first and second expansion valves 41 and 42 for decompressing and expanding the liquid refrigerant into a gas-liquid two-phase state, and the refrigerant passing through the first and second expansion valves 41 and 42 First and second evaporators 51 and 52 for evaporating are provided. The second expansion valve 42 and the second evaporator 52 are connected to the first expansion valve 41
And the first evaporator 51 are provided in parallel.

The first expansion valve 41 and the first evaporator 51 are provided in a front air-conditioning unit F disposed inside an instrument panel in a front part of the vehicle compartment, and provide air conditioning for a front seat side in the vehicle compartment. Used for The second expansion valve 42 and the second evaporator 52 are provided in a rear air-conditioning unit R disposed at the rear of the vehicle compartment, for example, at the ceiling of a wagon-type automobile, for air-conditioning the rear seat side in the vehicle compartment. used. Although not shown, the front and rear air conditioning units F,
It goes without saying that an air-conditioning blower and the like are built in R.

The instrument panel has a rear air conditioning switch 61 for switching the operation of the rear air conditioning unit R to stop.
The switch 61 is manually switched at the discretion of the occupant. Then, a signal from the switch 61 is input to the electric control device 62, and based on the input signal, opening / closing of the solenoid valves 6, 7 described later (the solenoid valves 6,
7 is turned on and off).

As is well known, the opening degrees of the first and second expansion valves 41 and 42 are automatically adjusted so as to maintain the degree of superheat of the refrigerant at the outlet of the first and second evaporators 51 and 52 at a predetermined value. This is a temperature-type expansion valve. This specific structure will be described using the expansion valve 42 as a representative. FIG. 1 shows the expansion valve 41.
The expansion valve 41 is also schematically shown in FIG.
Assume that it has the same structure as 2.

The expansion valve 42 has a valve body 10 in the form of a closed container. The upper inside of the valve body 10 is partitioned by a diaphragm 11 into a temperature sensing chamber 111 and a pressure equalizing chamber 112. The temperature sensing chamber 111 and the temperature sensing section 16 provided at the coolant outlet of the evaporator 52 are communicated with each other by a capillary tube 17, and inside these 111, 16, and 17, a refrigerant sealed in a refrigeration cycle is provided. And the same refrigerant as above. For this reason, the pressure in the temperature sensing chamber 111 becomes the saturation pressure P1 corresponding to the evaporator outlet refrigerant temperature sensed by the temperature sensing unit 16, and
This pressure P1 acts on the upper side of the diaphragm 11.

The pressure equalizing chamber 112 and the refrigerant outlet of the evaporator 52 are communicated by the outer equalizing pipe 18. For this reason, the pressure equalizing chamber 1
The pressure in the evaporator 52 becomes the pressure (evaporator pressure) P2 at the outlet of the refrigerant of the evaporator 52.
Acts on the lower side. A throttle passage 14 is formed below the equalizing chamber 112, and the opening of the throttle passage 14 is adjusted by the valve 13. The valve 13 and the diaphragm 1
1 is connected by an operating rod 12. A coil spring 15 is provided below the valve 13, and a predetermined spring force F3 is generated by the coil spring 15.
And act on the lower side of the diaphragm 11 via the operating rod 12.

The pressure P1 acting on the upper side of the diaphragm 11, the pressure P2 acting on the lower side, and the spring force F
The diaphragm 11 is moved up and down according to the difference from 3,
By transmitting this fluctuation to the valve body 13 via the operating rod 12, the opening degree of the throttle passage 14 in the expansion valve 42 is automatically adjusted to a required refrigerant flow rate, and the superheat degree of the refrigerant at the evaporator outlet is reduced. It is maintained at a predetermined value. Specifically, P1 is P2 +
When it becomes larger than F3, the diaphragm 11 is pushed down to open the throttle passage 14 in the expansion valve 42, and P2 + F3
Is greater than or equal to P1, the throttle flow path 14 in the expansion valve 42
Close.

Then, the refrigerant outlet sides of the first and second evaporators 51 and 52 join at a junction 53, and the junction 53
Refrigerant is sucked into the compressor 1. Here, the second
A first solenoid valve 6 for opening and closing the refrigerant flow path is provided in the refrigerant flow path between the downstream of the expansion valve 42 and the upstream of the second evaporator 52. Further, a second electromagnetic valve 7 for opening and closing the refrigerant flow path is provided in the refrigerant flow path between the downstream of the evaporator 52 and the upstream of the junction 53. In addition, the tip of the capillary tube 17 and the temperature sensing part 16 are located in the refrigerant flow path upstream of the solenoid valve 7. The solenoid valves 6 and 7 are normally closed solenoid valves, and are opened only when electricity is supplied.

The expansion valve 42 and the solenoid valve 6 have an integrated structure. As a result, the expansion valve 42 and the solenoid valve 6
Can be reduced in size. This integrated structure has been described in detail in Japanese Patent Application No. Hei 7-160739 filed earlier by the present applicant, and a description thereof will be omitted. Next, the operation of the above configuration will be described.

First, when the compressor 1 operates by receiving power from an engine of a vehicle via an electromagnetic clutch, the compressor 1 operates in the downstream flow path of the evaporators 51 and 52, that is, the refrigerant from the junction 53. Is sucked and compressed, and a high-temperature and high-pressure gas refrigerant is discharged toward the condenser 2. Then, the gas refrigerant is cooled and condensed in the condenser 2. The condensed refrigerant flows into the liquid receiver 3, gas-liquid of the refrigerant is separated, the liquid refrigerant flows out of the liquid receiver 3, and the first and second liquid refrigerants are arranged in parallel.
It goes to the expansion valves 41 and 42 side.

Here, when no occupant is on the rear seat side of the vehicle, there is no need to air-condition the rear seat side. Therefore, the rear air conditioning switch 61 is turned off, and the rear air conditioning unit R is not operated. As a result, the energization of the solenoid valve 6 and the solenoid valve 7 is shut off, and the solenoid valves 6 and 7 are closed, so that the inlet-side refrigerant flow path and the outlet-side refrigerant flow path of the second evaporator 52 are closed. No coolant is supplied.

On the other hand, on the front air conditioning unit F side, the liquid refrigerant from the receiver 3 is decompressed and expanded at the expansion valve 41,
It becomes a gas-liquid two-phase state of low temperature and low pressure. Since the gas-liquid two-phase refrigerant absorbs heat from the conditioned air in the evaporator 51 and evaporates, the conditioned air is cooled and becomes cool air, and air-conditions the front seat side in the passenger compartment. The opening degree of the expansion valve 41 is determined by the pressure P
It is automatically adjusted according to 1, P2 and the spring force F3, and maintains the superheat degree of the evaporator outlet refrigerant at a predetermined value.

When the solenoid valves 6 and 7 are closed, the rear air conditioning unit R side is at about room temperature, and the solenoid valve 7 allows the refrigerant to exit to the evaporator 51 at the refrigerant outlet side of the evaporator 52. Since the refrigerant circulation is blocked, the pressure P at the refrigerant outlet of the evaporator 52 (the position immediately before the solenoid valve 7)
Reference numeral 2 denotes the saturation pressure (eg, 0.6 MPa) of the refrigerant according to the room temperature (eg, 20 ° C.). Also, the pressure P1
Is the evaporator outlet refrigerant temperature sensed by the temperature sensing part 421, that is, the saturation pressure of the refrigerant according to the room temperature (for example, 0.6 MPa)
It is. Therefore, P1 = P2, and P1 <P2 + F
3, the diaphragm 11 does not move downward, and the expansion valve 42 is closed.

Here, the sealing property of the throttle passage 14 by the valve body 13 of the expansion valve 42 is not so reliable as compared with the sealing property of the refrigerant passage by the solenoid valves 6 and 7. 7, the expansion valve 42 is closed.
Is closed, the liquid refrigerant (temperature is about 60 ° C. and pressure is about 2 MPa) from the receiver 3 leaks little by little from the minute gap between the throttle channel 14 and the valve body 13, Solenoid valve 6
The liquid refrigerant stays at the site. In other words, the pressure is at the high pressure side up to the six electromagnetic valves. A saturated refrigerant (temperature: 20 ° C., pressure: about 0.6 MPa) corresponding to room temperature exists between the solenoid valve 6 and the solenoid valve 7, and an evaporator is provided downstream of the solenoid valve 7. Due to the circulation of the refrigerant to the 51 (operation of the compressor), a gas refrigerant (temperature: 10 ° C., pressure: about 0.3 MPa) exists.

Next, when the rear air-conditioning switch 61 is turned on to operate the rear air-conditioning unit R while the expansion valve 42 is closed as described above, the solenoid valves 6 and 7 are simultaneously operated. Power is supplied to the solenoid valves 6 and 7 at the same time, and the refrigerant flow paths at the solenoid valves 6 and 7 are opened. By the way, when the solenoid valves 6 and 7 are closed, the pressure on the upstream side of the solenoid valves 6 is at the high pressure side. Immediately after the valve is opened, the expansion valve 42 is in the closed state, so that the generation of noise due to the pressure fluctuation can be effectively suppressed, and the large flow of the refrigerant can be suppressed from rapidly flowing out. Generation of flowing noise and the like can be effectively suppressed.

Specifically, after opening the solenoid valves 6 and 7,
Although the pressure P2 at the refrigerant outlet of the evaporator 52 rapidly decreases, the pressure in the pressure equalizing chamber 112 of the diaphragm 11 gradually approaches the pressure P2 via the capillary tube 17, so that the valve element of the expansion valve 42 13 also gradually increases, and as a result, the flow rate of the refrigerant passing through the expansion valve 42 also gradually increases. Therefore, it is possible to effectively suppress the generation of noise due to the pressure fluctuation and the generation of refrigerant flow noise and the like.

After a predetermined period of time has elapsed after the solenoid valves 6 and 7 have been opened, the pressure in the pressure equalizing chamber 112 of the diaphragm 11 becomes the refrigerant pressure P2 itself. , The valve element 13 of the expansion valve 42 is displaced to a position corresponding to the balance with the pressure P2 + F3. Thereby, the valve element 13 of the expansion valve 42 adjusts the opening degree of the throttle flow path 14 to adjust the flow rate of the refrigerant so that the evaporator outlet refrigerant maintains the predetermined degree of superheat. That is, the expansion valve 42 adjusts the refrigerant flow rate as an external pressure equalizing type expansion valve.

Next, the results of an experiment and a study by the present inventor on pressure fluctuations generated when the solenoid valves 6 and 7 are opened will be described based on the graphs shown in FIGS. 2 (a) and 2 (b). First, as the refrigeration cycle, one shown in FIG. 1 (the present invention) and one in which the solenoid valve 7 was eliminated from the refrigeration cycle shown in FIG. 1 (conventional product) were prepared. And the temperature is 30 ° C
Then, in an actual vehicle placed in an atmosphere having a relative humidity of 50%, the rotation speed of the compressor 1 was set to 800 r / m, the solenoid valve 6, 7 was closed for the product of the present invention, and Operates the refrigeration cycle with the solenoid valve 6 closed. And the high pressure side pressure of the evaporator 51 is 2.0
After adjusting the air flow (heat exchange amount) to the evaporator 51 and the condenser 2 so that the pressure on the low pressure side becomes 0.3 MPa, and after operating for about 30 minutes in this state, the solenoid valves 6 and 7 are operated.
Was opened.

FIG. 2 (a) shows the result of measuring the pressure fluctuation immediately before the expansion valve 42 when the solenoid valves 6 and 7 are opened.
(Product of the present invention) and FIG. 2B (conventional product). Note that the horizontal axis of this graph is the time (seconds) when the solenoid valves 6 and 7 are opened as 0, and the vertical axis is
This is the pressure at the upstream position immediately before the expansion valve 42. According to this graph, it was confirmed that the pressure fluctuation at the upstream position immediately before the expansion valve 42 was about 1 MPa in the conventional product, whereas the pressure fluctuation was about 0.4 MPa in the product of the present invention. As a result, it has been found that according to the present invention, it is possible to effectively suppress the pressure fluctuation at the electromagnetic valve 6 from propagating to the upstream side of the expansion valve 42, and it is possible to effectively suppress the noise due to the pressure fluctuation.

When the rear air conditioning unit R is not operated again, the power supply to the solenoid valves 6 and 7 is stopped at the same time, and the solenoid valves 6 and 7 are closed at the same time. (Second Embodiment) In the first embodiment, the outer equalizing pipe 1 is used.
8, the pressure equalizing chamber 112 communicates with the outlet of the evaporator 52, and the evaporator pressure at the evaporator outlet is introduced into the pressure equalizing chamber 112. However, the present embodiment shown in FIG. Equalizing pipe 1
8, the pressure equalizing chamber 112 communicates with the inlet of the evaporator 52 (specifically, the refrigerant flow path between the downstream of the solenoid valve 6 and the upstream of the evaporator 52). Evaporator pressure at 52 inlet is introduced. That is, the expansion valve 4
Reference numerals 1 and 42 adjust the flow rate of the refrigerant as internal pressure equalizing type expansion valves. The operation of this embodiment is the same as that of the first embodiment, and the same effects can be obtained. The specific structure of the expansion valve according to the present embodiment is described in
Since it is described in Japanese Patent Application Laid-Open No. 51422, the description here is omitted.

(Other Embodiments) In the above embodiment, the solenoid valve 6 and the solenoid valve 7 are simultaneously opened. However, the solenoid valve 6 is opened earlier for a very short time (for example, 1 to 2 seconds). Is also good. This also provides the same effects as the above embodiment. However, if the solenoid valve 6 is opened after the solenoid valve 7 is opened first, the expansion valve 42 may be opened during this time, and the problem of the prior art may occur. , 7 may be opened simultaneously, or the solenoid valve 6 may be opened a short time earlier.

In the above embodiment, the solenoid valve 6 and the solenoid valve 7 are closed at the same time. However, one of them may be closed earlier for a very short time (for example, 1 to 2 seconds). This also provides the same effects as the above embodiment. However,
After closing the solenoid valve 6 first and then closing the solenoid valve 7 after a lapse of more than a minute time (for example, 10 seconds), during this time, the downstream side of the solenoid valve 6 circulates refrigerant to the other evaporator. Since the pressure becomes low due to (compressor operation) and the expansion valve may open, it is preferable to close the solenoid valves 6 and 7 at the same time or close the solenoid valve 7 for a short time.

Here, when the solenoid valve 6 is closed after a lapse of a very short time (for example, 60 seconds) after the solenoid valve 7 is closed, the liquid refrigerant from the receiver 3 is discharged during this time. There is a possibility that the electromagnetic valve 7 may accumulate in the upstream side of the electromagnetic valve 7, that is, in the evaporator 52, through a gap between the throttle passage 14 of the expansion valve 42 and the valve body 13. When the electromagnetic valve 7 is closed (at the same time or at the same time, the pressure fluctuates at the seven positions, and this fluctuation causes the evaporator 52 to vibrate through the liquid refrigerant in the evaporator 52 and may generate noise. It is necessary to close the solenoid valve 6 before and after a very short time).

In the above embodiment, the solenoid valves 6 and 7 (first and second solenoid valves in the claims) are provided only in the rear air conditioning unit R. However, the first air conditioning unit F is also provided in the front air conditioning unit F. ,
A second solenoid valve may be provided. Then, only the rear air conditioning unit R may be operated, and the front air conditioning unit F may not be operated. In the above embodiment, the present invention is applied to a refrigeration cycle having two expansion valves 41 and 42 and evaporators 51 and 52, but may be applied to a refrigeration cycle having three or more expansion valves and evaporators.

In the above embodiment, the saturation pressure P1 corresponding to the evaporator outlet refrigerant temperature and the evaporators 51, 5
The opening degree of the expansion valve 42 was adjusted by changing the diaphragm 11 based on the evaporator pressure P2 at the refrigerant outlet of the second evaporator. However, the temperature sensor detects the evaporator outlet refrigerant temperature, The pressure detector detects the evaporator pressure P2, calculates the degree of superheat at the refrigerant outlet of the evaporator based on the detection result, and maintains the degree of superheat at a predetermined value.
The opening degree of the expansion valve may be electrically adjusted (for example, by a step motor or a linear solenoid).

Further, the present invention is not limited to a refrigeration cycle applied to a vehicle air conditioner, but may be applied to a refrigeration cycle used also as an air conditioner or a refrigerator installed in a general building. In a refrigeration cycle having two refrigerating units, the present invention may be applied to both units, or the present invention may be applied to either one of the units.

[Brief description of the drawings]

FIG. 1 is a schematic refrigeration cycle diagram according to a first embodiment of the present invention.

FIG. 2A is a graph showing pressure fluctuations in the refrigeration cycle of the first embodiment, and FIG. 2B is a graph showing pressure fluctuations in a conventional refrigeration cycle.

FIG. 3 is a schematic refrigeration cycle diagram according to a second embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Compressor, 2 ... Condenser, 41,42 ... Expansion valve (1st,
Evaporator (first and second evaporators), 53, confluence section, 6, 7 solenoid valve (first and second expansion valves), P1 evaporator pressure, P2 ... Saturation pressure.

Claims (2)

[Claims] A compressor for compressing and discharging a refrigerant (1)
A condenser (2) for condensing the gas refrigerant discharged from the compressor (1); a first expansion valve (41) for decompressing and expanding the liquid refrigerant condensed in the condenser (2); A second expansion valve (42) provided in parallel with the first expansion valve (41) and configured to decompress and expand the liquid refrigerant condensed by the condenser (2); and a refrigerant decompressed and expanded by the first expansion valve (41). And a second evaporator (52) provided in parallel with the first evaporator (51) and evaporating the refrigerant decompressed and expanded by the second expansion valve (42). And the first evaporator (51) and the second evaporator (52).
A merging section (53) for merging the refrigerant evaporated in the step (a). In a refrigeration cycle in which the refrigerant from the merging section (53) is sucked into the compressor (1), the refrigerant flows downstream of the second expansion valve (42). The second evaporator (52)
A first electromagnetic valve (6) for opening and closing a refrigerant flow path between the upstream and an upstream; and a second electromagnetic valve for opening and closing a refrigerant flow path between the downstream of the second evaporator (52) and the upstream of the junction (53). A valve (7), the second expansion based on the evaporator pressure (P2) downstream of the first solenoid valve (6) and the evaporator outlet refrigerant temperature upstream of the second solenoid valve (7). The first electromagnetic valve (6) and the second electromagnetic valve (7) when adjusting the valve opening of the valve (42) to shut off the supply of the refrigerant to the second evaporator (52).
The refrigeration cycle is characterized in that the first solenoid valve (6) and the second solenoid valve (7) are opened when refrigerant is supplied to the second evaporator (52). 2. A refrigeration cycle according to claim 1, further comprising:
An air conditioner for a vehicle, wherein the first evaporator (51) cools the front side of the cabin and the second evaporator (52) cools the rear side of the cabin.