JP2004020160A - Vapor compression type refrigerator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent abnormal noise from being generated from an opening/closing valve provided on an upstream side of a decompressor. <P>SOLUTION: This vapor compression type refrigerator is provided with a second bypass passage 13, and first and second check valves 15 and 12. This constitution allows refrigerant in a low pressure side refrigerant passage 17 to flow to the side of a first bypass passage 14 in defrosting operation. This constitution can prevent the refrigerant pressure in the side of the condenser 3 of the opening/closing valve 6 from lowering quicker than the refrigerant pressure in the low-pressure side refrigerant passage 17 so as to prevent an inverse pressure in the normal operation from applying to the opening/closing valve 6, prevent a movable part of the opening/closing valve 6 from vibrating, and sufficiently reduce the abnormal noise. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a vapor compression refrigerator that transfers heat on a low temperature side to a high temperature side, and is effective when applied to a vehicle-mounted refrigerator such as a refrigerator car.
[0002]
[Prior art]
As an in-vehicle refrigerator for a refrigerating vehicle, for example, in the invention described in Japanese Patent Application Laid-Open No. 2001-280807, a high-pressure / high-temperature refrigerant (hot gas) discharged from a compressor 1 is guided to an evaporator 9 as shown in FIG. A bypass valve 7 for opening and closing the bypass passage 14 and an opening and closing valve 6 for opening and closing the refrigerant passage upstream of the expansion valve 8 are provided. The bypass valve 7 is opened with the opening and closing valve 6 closed, and hot gas is supplied to the evaporator 9. The frost adhering to the surface of the evaporator 9 is removed (defrosted).
[0003]
The on-off valve 6 is for suppressing hot gas from flowing to the condenser 3 and the expansion valve 8 when the bypass valve 7 is opened, that is, during the defrosting operation.
[0004]
[Problems to be solved by the invention]
However, according to the invention described in the above-mentioned publication, during the defrosting operation, a pressure is applied to the on-off valve in a direction opposite to that in the normal operation. There is a high possibility that sound is generated.
[0005]
Here, the normal operation refers to an operation mode in which the refrigerant is circulated in the order of the compressor 1, the condenser 3, the receiver 5, the on-off valve 6, the evaporator 9, the accumulator 11, and the compressor 1.
[0006]
In view of the above points, the present invention firstly provides a novel vapor compression refrigerator different from the conventional one, and secondly, differs from an on-off valve provided upstream of a decompressor such as an expansion valve. It is intended to prevent generation of sound.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, in the present invention, there is provided a vapor compression refrigerator for transferring low-temperature heat to a high-temperature side, wherein the compressor sucks and compresses a refrigerant. A high-pressure heat exchanger (3) for cooling the high-pressure refrigerant discharged from the compressor (1); and a decompressor (8) for decompressing and expanding the high-pressure refrigerant cooled in the high-pressure heat exchanger (3). ), A low-pressure heat exchanger (9) for evaporating the low-pressure refrigerant depressurized by the decompressor (8), and a second heat exchanger that guides the high-pressure refrigerant to the low-pressure heat exchanger (9) bypassing the decompressor (8). A first bypass passage (14); a bypass valve (7) for switching between a case where the refrigerant flows through the first bypass passage (14) and a case where the refrigerant is prohibited from flowing through the first bypass passage (14); 8) an on-off valve (6) provided on the upstream side of the refrigerant flow for opening and closing the refrigerant passage; 8) a low pressure side refrigerant passage (17) connecting the on-off valve (6), a second bypass passage (13) connecting the first bypass passage (14), and a first bypass from the low pressure side refrigerant passage (17). A first check valve (15) for allowing the refrigerant to flow only to the passage (14) side.
[0008]
This allows the refrigerant in the low-pressure side refrigerant passage (17) to flow toward the first bypass passage (14), so that the refrigerant pressure on the high-pressure side heat exchanger (3) side from the on-off valve (6) is reduced to the low-pressure side. It is possible to prevent the refrigerant pressure in the refrigerant passage (17) from dropping earlier than the refrigerant pressure.
[0009]
Therefore, it is possible to prevent the reverse pressure from acting on the on-off valve (6), so that it is possible to prevent the movable part of the on-off valve (6) from vibrating, and to sufficiently reduce the generation of abnormal noise. It is possible to obtain a new vapor compression refrigerator different from the conventional one.
[0010]
According to the second aspect of the invention, the second check valve (12) that allows the refrigerant to flow only from the on-off valve (6) side to the decompressor (8) side is provided in the low-pressure side refrigerant passage (17). It is characterized by being carried out.
[0011]
According to a third aspect of the present invention, there is provided a defrost control means for opening the bypass valve (7) and closing the on-off valve (6) when the compressor (1) is stopped. .
[0012]
Incidentally, the reference numerals in parentheses of the respective means are examples showing the correspondence with specific means described in the embodiments described later.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
In the present embodiment, the vapor compression refrigerator according to the present invention is applied to a vehicle-mounted refrigerator for a refrigerator vehicle, and FIG. 1 is a schematic diagram of the vehicle-mounted refrigerator.
[0014]
The compressor 1 receives power from a traveling engine or a dedicated drive source via an electromagnetic clutch to suck and compress refrigerant, and the oil separator 2 separates and extracts refrigeration oil from the refrigerant discharged from the compressor 1. It is an oil separator.
[0015]
The condenser 3 is a high-pressure side heat exchanger that cools the heat of the high-temperature and high-pressure refrigerant discharged from the compressor 1 into the outside air. The blower 4 blows cooling air to the condenser 3, and the receiver 5 Is a high-pressure gas-liquid separator that separates the refrigerant flowing out of the condenser 3 into a gas-phase refrigerant and a liquid-phase refrigerant and supplies the liquid-phase refrigerant to the pressure reducer 8.
[0016]
The decompressor 8 is a temperature-type expansion valve that variably controls the opening degree of the throttle so that the degree of superheat of the refrigerant flowing out of the evaporator 9 becomes a predetermined value. An on-off valve 6 for opening and closing the refrigerant passage is provided in the refrigerant passage connecting to the pressure reducer 8.
[0017]
The evaporator 9 is a low-pressure side heat exchanger that evaporates the liquid-phase refrigerant by exchanging heat between the refrigerant depressurized by the decompressor 8 and the air blown into the storage, and the blower 10 supplies the air in the storage to the evaporator 9. The accumulator 11 separates the refrigerant flowing out of the evaporator 9 into a gas-phase refrigerant and a liquid-phase refrigerant, and supplies the gas-phase refrigerant to the suction side of the compressor 1. It is.
[0018]
The first bypass passage 14 is a passage that guides the hot gas discharged from the compressor 1 to the evaporator 9 while bypassing the condenser 3 and the decompressor 8. The first bypass passage 14 includes a first bypass passage 14. By opening and closing the bypass valve, a bypass valve 7 for switching between a case where the refrigerant flows through the first bypass passage 14 and a case where the refrigerant is prohibited from flowing through the first bypass passage 14 is provided.
[0019]
Since the bypass valve 7 and the on-off valve 6 control the flow of the high-pressure refrigerant, a pilot-type solenoid valve is employed in the present embodiment, and both valves 6 and 7 are electrically controlled by the electronic control unit 16. Have been.
[0020]
The second bypass passage 13 is a refrigerant passage that connects the low-pressure side refrigerant passage 17 that connects the pressure reducing device 8 to the on-off valve 6 and the first bypass passage 14. The second bypass passage 13 has a low-pressure side refrigerant passage 17. A first check valve 15 that allows the refrigerant to flow only to the first bypass passage 14 side is provided.
[0021]
The second bypass passage 13 is connected to the on-off valve 6 side of the low-pressure side refrigerant passage 17 from the second check valve 12. Here, the second check valve 12 is a valve that allows the refrigerant to flow only from the on-off valve 6 side to the decompressor 8 side.
[0022]
Next, the characteristic operation of the present embodiment will be described.
[0023]
FIG. 2 is a chart showing an operation mode and a control mode of each device. The ON state of the compressor 1 means that the compressor 1 is operated by connecting the electromagnetic clutch, and the OFF state of the compressor 1 means that the compressor 1 is stopped by disconnecting the electromagnetic clutch.
[0024]
1. Refrigeration operation mode In this mode, the interior of the refrigerator is cooled, and the compressor 1 and the blowers 4 and 10 are operated with the on-off valve 6 opened and the bypass valve 7 closed.
[0025]
As a result, the liquid-phase refrigerant absorbs heat from the air blown into the storage in the evaporator 9 and evaporates to cool the storage, and the evaporated gas-phase refrigerant is compressed and heated by the compressor 1 to the outside air temperature or higher. The heat absorbed by the condenser 3 is released to the outside air and condensed.
[0026]
2. Defrosting operation mode This mode is a mode for removing frost adhering to the surface of the evaporator 9, and stops the compressor 1 and the blowers 4, 10 with the on-off valve 6 closed and the bypass valve 7 opened. .
[0027]
As a result, the high-pressure refrigerant remaining on the high-pressure side (discharge side) flows into the evaporator 9 via the first bypass passage 14, so that the evaporator 9 is heated from the inside and the frost adhering to the surface of the evaporator 9 is heated. Is removed.
[0028]
Next, the operation and effect of the present embodiment will be described.
[0029]
FIG. 3 is a schematic view of a prototype test of a vapor compression refrigerator in order to prevent the generation of abnormal noise from the on-off valve 6, which is a second problem to be solved by the present invention. The second bypass passage 13 and the first check valve 15 are eliminated from the vapor compression refrigerator according to the present embodiment.
[0030]
In this prototype, since the check valve 12 is provided in the low-pressure side refrigerant passage 17, the high-pressure refrigerant provided on the evaporator 9 side flows from the first bypass passage 14 to the on-off valve 6 side during the defrosting operation. The refrigerant in the low-pressure side refrigerant passage 17 is sealed between the on-off valve 6 and the decompressor 8, whereas the refrigerant pressure on the condenser 3 side from the on-off valve 6 7, the refrigerant pressure on the condenser 3 side from the on-off valve 6 drops earlier than the refrigerant pressure in the low-pressure side refrigerant passage 17.
[0031]
Therefore, even if the check valve 12 is provided, since the pressure in the opposite direction to that in the normal operation acts on the on-off valve 6, the movable portion of the on-off valve 6 vibrates, and the generation of abnormal noise is sufficiently reduced. I couldn't.
[0032]
On the other hand, in the present embodiment, as shown in FIG. 1, the second bypass passage 13 is provided, so that the refrigerant in the low-pressure side refrigerant passage 17 flows to the first bypass passage 14 during the defrosting operation. Can be.
[0033]
Accordingly, it is possible to prevent the refrigerant pressure on the condenser 3 side from the on-off valve 6 from dropping earlier than the refrigerant pressure in the low-pressure side refrigerant passage 17, so that a pressure acting on the on-off valve 6 in a direction opposite to that in the normal operation is applied. Can be prevented, the movable portion of the on-off valve 6 can be prevented from vibrating, and the generation of abnormal noise can be sufficiently reduced.
[0034]
Incidentally, FIG. 4 is a test result showing the pressure and temperature behavior before and after the on-off valve 6. As is clear from FIG. 4 (particularly, see FIG. 4A), in this embodiment, the defrosting operation mode is set. After time (time 0), it can be seen that the direction of the pressure difference is always the same as during normal operation, whereas in the past, the direction of the pressure difference is always opposite to that during normal operation.
[0035]
As is clear from the above description, even if the second check valve 12 is abolished, the refrigerant pressure on the condenser 3 side from the on-off valve 6 drops earlier than the refrigerant pressure in the low-pressure side refrigerant passage 17. Can be prevented, so that the movable portion of the on-off valve 6 can be prevented from vibrating.
[0036]
(Other embodiments)
In the above-described embodiment, a temperature-type expansion valve is employed as the pressure reducing device 8. However, the present invention is not limited to this, and may be a capillary tube or a fixed throttle.
[0037]
In this case, it is desirable that the compressor 1 be driven by a dedicated drive source such as a motor.
[0038]
In the above-described embodiment, the defrosting operation is performed with the compressor 1 stopped. However, the defrosting operation may be performed with the compressor 1 operating.
[0039]
Further, in the above-described embodiment, the present invention is applied to the refrigerator car, but the application of the present invention is not limited to this.
[Brief description of the drawings]
FIG. 1 is a schematic view of a vehicle-mounted refrigerator according to an embodiment of the present invention.
FIG. 2 is a table showing an operation mode of a vehicle-mounted refrigerator according to an embodiment of the present invention and a control mode of each device.
FIG. 3 is a schematic diagram of a vapor compression refrigerator that has been subjected to a trial production test.
FIG. 4 is a graph showing pressure and temperature behavior before and after the on-off valve 6.
FIG. 5 is a schematic view of a vapor compression refrigerator according to a conventional technique.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Compressor, 3 ... Condenser, 6 ... On-off valve, 7 ... Bypass valve, 8 ... Decompressor,
9 evaporator, 13 second bypass passage, 14 first bypass passage
15: first check valve, 12: second check valve.

Claims (3)

A vapor compression refrigerator that transfers heat on the low temperature side to the high temperature side,
A compressor (1) for sucking and compressing a refrigerant;
A high-pressure side heat exchanger (3) for cooling the high-pressure refrigerant discharged from the compressor (1),
A decompressor (8) for decompressing and expanding the high-pressure refrigerant cooled in the high-pressure side heat exchanger (3);
A low-pressure side heat exchanger (9) for evaporating the low-pressure refrigerant decompressed by the pressure reducer (8);
A first bypass passage (14) for bypassing the pressure reducer (8) to guide the high-pressure refrigerant to the low-pressure side heat exchanger (9);
A bypass valve (7) for switching between a case where the refrigerant flows through the first bypass passage (14) and a case where the refrigerant is prohibited from flowing through the first bypass passage (14);
An on-off valve (6) provided on the upstream side of the refrigerant flow of the pressure reducer (8), for opening and closing a refrigerant passage;
A low pressure side refrigerant passage (17) connecting the pressure reducer (8) and the on-off valve (6), a second bypass passage (13) connecting the first bypass passage (14),
A vapor compression refrigerator comprising: a first check valve (15) that allows refrigerant to flow only from the low-pressure side refrigerant passage (17) to the first bypass passage (14). A second check valve (12) that allows refrigerant to flow only from the on-off valve (6) side to the decompressor (8) side is provided in the low-pressure side refrigerant passage (17). The vapor compression refrigerator according to claim 1, wherein: When the compressor (1) is stopped, a decompression control means for opening the bypass valve (7) and closing the on-off valve (6) is provided.

Images