JPH07301461A - Cooling cycle - Google Patents

Abstract

PURPOSE:To protect an evaporator against a pressure fed from a discharge side to a suction side after a compressor is stopped by providing pressure regulating means for preventing the pressure of a low-pressure channel from becoming a predetermined pressure or more on the channel for communicating a refrigerant output side of the evaporator with the suction side of the compressor. CONSTITUTION:At the time of stopping a compressor 4, a solenoid valve 12 is opened to open a bypass passage 11 and the first high-pressure channel 8 of the discharge side of the compressor 4 communicates with a low-pressure channel 10 of the suction side thereby to eliminate a pressure difference between the high pressure side and the low pressure side of the compressor 4, and a driving torque at the time of restarting the compressor 4 is reduced. In such a facility, pressure regulating means is provided at the channel 10 to limit that the pressure of the channel 10 does not become a resistant pressure or more of an evaporator. As the means, a relief valve 13 is provided and opened when the pressure of the predetermined value or more is applied to the channel 10, thereby externally discharging the refrigerant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling cycle mounted on an automobile air conditioner.

[0002]

2. Description of the Related Art A conventional cooling (freezing) cycle is disclosed, for example, in Japanese Utility Model Laid-Open No. 1-91858, and includes a compressor 10, a condenser 12, a receiver 14, and an expansion valve 1.
8 and the evaporator 6 are connected in series by piping. In this cooling cycle, the compressor 10
The gas refrigerant compressed in (1) is condensed (liquefied) by heat dissipation when passing through the condenser 12, and becomes a high-pressure liquid refrigerant. The liquid refrigerant is separated from the excess gas separated by the liquid receiver 14 and reaches the expansion valve 18 in a liquid state. In this expansion valve 18, the high-pressure liquid refrigerant is adiabatically expanded,
It becomes low-pressure moist steam. This low-pressure wet vapor is vaporized (vaporized) by suction when passing through the evaporator 6, and returns to the compressor 10.
This constitutes a cooling cycle in which the heat absorbed by the evaporator 6 is radiated from the condenser 12. This reference is characterized in that, in such a cooling cycle, a relief valve for extracting the refrigerant from the refrigerant passage when the refrigerant exceeds an appropriate amount is provided between the receiver and the expansion valve. .

Further, in the cooling cycle as described above, when the cooling cycle is mounted on, for example, an electric vehicle, since the drive source of the compressor is an electric motor, it is necessary to reduce the rotational torque of the compressor within a short time. is there. Therefore, for the purpose of reducing the starting torque of the compressor, it is known that the discharge side and the suction side of the compressor are made to communicate with each other after the cooling cycle is stopped so as to eliminate the pressure difference between the high pressure side and the low pressure side. ing.

[0004]

However, the pressure in the high-pressure passage from the discharge side of the compressor to the refrigerant inflow side of the condenser is usually about 12 to 13 Kg / cm ² , and the pressure resistance of the evaporator is usually about 15 Kg / cm ^2. However, in order to eliminate the pressure difference between the high pressure side and the low pressure side of the compressor and reduce the starting torque, when the discharge side and the suction side of the compressor are connected, high pressure refrigerant flows from the high pressure passage to the evaporator side. May cause the evaporator to burst.

From the above, it is possible to solve the above-mentioned problems by improving the breakdown voltage of the evaporator as much as that of a condenser, but in the present situation of aiming to reduce the weight of a vehicle, it goes against the trend of the times and the conventional cooling. Since it becomes difficult to use the cycle as it is, the cost is increased.

Therefore, according to the present invention, when the discharge side and the suction side of the compressor are connected after the compressor is stopped, the evaporator can be protected from the high pressure refrigerant flowing from the discharge side to the suction side of the compressor. To provide a cycle.

[0007]

Therefore, the present invention is
A compressor that compresses the refrigerant, a condenser that condenses the refrigerant discharged from this compressor, an expansion valve that adiabatically expands the refrigerant condensed by this condenser into wet steam, and a refrigerant that has been made wet steam by the expansion valve. In a cooling cycle including at least an evaporator for evaporating, a bypass passage that connects the discharge side and the suction side of the compressor, and a solenoid valve that opens and closes the bypass passage, a refrigerant outflow side of the evaporator and the The pressure adjusting means for preventing the pressure in the low pressure passage from exceeding a predetermined pressure is provided on the low pressure passage communicating with the suction side of the compressor (claim 1).

The pressure adjusting means is a pressure release valve that opens at a pressure lower than the pressure resistance of the evaporator (claim 2), and the pressure release valve has a pressure of 1.3 MPa.
It is preferable to open at a pressure of [13 Kg / cm ² ] or more (claim 3).

The pressure adjusting means may be an accumulator (claim 4).

[0010]

Therefore, according to the present invention, the pressure adjusting means for preventing the pressure in the low pressure passage from exceeding the predetermined pressure is provided on the low pressure passage connecting the refrigerant outflow side of the evaporator and the suction side of the compressor. By providing the evaporator, the bypass passage is opened after the compressor is stopped, the discharge side and the suction side of the compressor communicate with each other, and the high pressure can be limited to a predetermined pressure or less even when the high pressure flows into the low pressure passage. Can be protected and the above problems can be achieved.

Further, since the pressure adjusting means is a pressure release valve provided in the low pressure passage, the refrigerant can be discharged to the outside when the pressure in the low pressure passage exceeds a predetermined pressure. In addition, the evaporator can be protected. Also, the pressure resistance of the normal evaporator is 1.5
To be Mpa [15 Kg / cm ^2], the pressure was set to operate the pressure release valve to 1.3 MPa for [13 kg / cm ^2], since the pressure relief valve opens at a pressure above 1.3 MPa for, evaporator Can be protected.

Further, since the pressure adjusting means is an accumulator and the pressure of the refrigerant flowing into the low pressure passage can be absorbed by the accumulator, the evaporator can be protected.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

The cooling (refrigeration) cycle 1 shown in FIGS. 1 and 2 is mounted in, for example, an air conditioner for a vehicle, and an evaporator 3, a compressor 4, a condenser 5, a liquid receiver arranged in an air conditioning duct 2 are provided. 6 and the expansion valve 7 are connected in series by piping to form a cycle.

In this cooling cycle 1, the high-temperature and high-pressure gas refrigerant compressed by the compressor 4 flows into the condenser 5 through the first high-pressure flow path 8 as shown by the solid arrow in FIG. At 5, the heat is dissipated, condensed (liquefied), and changed into a high-pressure low-temperature liquid refrigerant. The liquid refrigerant is adjusted in gas-liquid separation and refrigerant flow rate in the liquid receiver 6, reaches the expansion valve 7 via the second high-pressure flow passage 9, and is decompressed by passing through the expansion valve 7 to have a low temperature and low pressure. It becomes wet steam. The wet steam flows into the evaporator 3, absorbs heat in the evaporator 3 and evaporates (vaporizes) to change into a low-pressure gas refrigerant, and returns to the suction side of the compressor 4 via the low-pressure passage 10. As a result, the evaporator 3
A cooling cycle is constructed in which the heat absorbed by the condenser 5 is radiated by the condenser 5, and the air passing through the air conditioning duct 2 can be cooled.

In the above cooling cycle 1, when the compressor 4 is stopped, the pressure difference between the high pressure side and the low pressure side is maintained for a long time because the flow passage resistance of the expansion valve 7 is large. Therefore, when the compressor 4 is restarted, the driving torque becomes considerably large while the pressure difference between the high pressure side and the low pressure side is maintained, and the power loss at the time of restarting the compressor becomes considerably large. . This power loss poses a serious problem in an air conditioner for an electric vehicle, for example, because the power source is a battery. Further, in order to obtain this driving torque with the electric motor, it is necessary to use a large electric motor, which is an obstacle to weight reduction of the vehicle.

To this end, a bypass passage 11 that bypasses the first high-pressure passage 8 and the low-pressure passage 10 is provided, and an electromagnetic valve 12 that opens and closes the bypass passage 11 is provided. The bypass passage 11 is opened by opening the valve 12, and the first high-pressure passage 8 on the discharge side of the compressor 4 and the low-pressure passage 10 on the suction side of the compressor 4 are communicated with each other, whereby the compressor 4
The pressure difference between the high pressure side and the low pressure side can be eliminated, and the drive torque when the compressor 4 is restarted can be reduced. Further, in order to shorten the time until the compressor 4 can be restarted, the pressure difference between the high pressure side and the low pressure side can be eliminated in a short time.

However, the first high-pressure channel 8 and the low-pressure channel 10
When they are communicated with each other, the high pressure refrigerant flows into the low pressure passage 10. Usually, the pressure of the refrigerant in the first high-pressure flow path 8 is about 1.2 to 1.3 MPa (about 12 to 13 Kg / cm).
² ], and the withstand pressure of the evaporator 3 is about 1.5 Mp.
Since it is a [about 15 Kg / cm ² ], there is no problem during normal operation of the cooling cycle. However, as can be seen from the above numbers, the difference between the high pressure and the withstand pressure of the evaporator is not so large that there is a risk that the evaporator will burst if an abnormality occurs in which the high pressure rises.

To this end, the present invention provides the low pressure flow path 10
A pressure adjusting means is provided in the above to prevent the pressure in the low-pressure passage 10 from exceeding the withstand pressure of the evaporator.

In the cooling cycle 1 shown in FIGS. 1 and 2, a pressure release valve (relief valve) 13 is provided in the low pressure passage 10 as the pressure adjusting means, and a pressure higher than a predetermined pressure is applied to the low pressure passage 10. In this case, the relief valve 13 is opened to release the refrigerant to the outside.

The opening pressure of the relief valve 13 is 1.2 to 1.3 MPa (about 1) in the pressure range of the first high-pressure passage 8.
^{2 to} 13 kg / cm ² ], it is desirable to set the upper limit value to 1.3 Mpa. As a result, as shown by the broken line arrow in FIG. 2, when a high pressure of 1.3 MPa or more flows into the low pressure passage 10, the relief valve 13 is opened and the pressure of the high pressure refrigerant becomes 1.3 MPa or less. The refrigerant is released, and the evaporator 3 can be protected. Although the relief valve 13 may release the refrigerant even at a high pressure when the pressure suddenly rises, the relief valve 13 may be discharged from the relief valve 13 at an abnormal pressure raised due to a constant failure. Since the refrigerant is released to stop the cooling cycle (when the refrigerant amount becomes equal to or less than a predetermined value, the safety device works and the compressor stops), it is possible to recognize the failure of the cooling cycle.

In the cooling cycle 1 shown in FIG. 3, the accumulator 14 as the pressure adjusting means is used as the low pressure passage 10.
It was installed in. As a result, the pressure of the high-pressure refrigerant that has flowed into the low-pressure passage 10 through the bypass passage 11 due to the opening of the solenoid valve 12 is absorbed by the accumulator 14 so that the pressure is reduced, and the evaporator 3 receives the high-pressure pressure. Can be prevented. This accumulator 14 can protect the evaporator from high pressure without releasing the refrigerant when the pressure suddenly rises.

Further, the relief valve 13 and the accumulator 14 are simultaneously provided in the low-pressure passage 10, so that the above effects can be synergized.

[0024]

As described above, according to the present invention, it is possible to prevent the pressure of the low pressure passage from becoming equal to or higher than a predetermined pressure on the low pressure passage connecting the refrigerant outflow side of the evaporator and the suction side of the compressor. By providing the pressure adjusting means for preventing, even after the compressor is stopped, the bypass passage is opened and the discharge side and the suction side of the compressor are communicated with each other, and even when the high pressure flows into the low pressure passage, the high pressure is kept below the predetermined pressure. The evaporator can be protected by limiting to.

As a result, the safety of the evaporator can be secured, and the conventional cooling cycle can be used as it is, so that the cost increase can be suppressed.

[Brief description of drawings]

FIG. 1 is a configuration diagram when a pressure release valve is used as a pressure adjusting means in a cooling cycle according to an embodiment of the present invention, and shows a flow of a refrigerant when a compressor is in operation.

FIG. 2 is a configuration diagram in the case where a pressure release valve is used as a pressure adjusting means in the cooling cycle according to the embodiment of the present invention, showing a flow of the refrigerant when the bypass passage is opened when the compressor is stopped. is there.

FIG. 3 is a configuration diagram when an accumulator is used as a pressure adjusting means in the cooling cycle according to the embodiment of the present invention, and shows a flow of the refrigerant when the bypass passage is opened when the compressor is stopped.

[Explanation of symbols]

 1 Cooling Cycle 2 Air Conditioning Duct 3 Evaporator 4 Compressor 5 Condenser 6 Liquid Receiver 7 Expansion Valve 8 First High Pressure Flow Path 9 Second High Pressure Flow Path 10 Low Pressure Flow Path 11 Bypass Passage 12 Solenoid Valve 13 Pressure Release Valve (Relief Valve) ) 14 Accumulator

Claims (4)

[Claims] 1. At least a compressor for compressing a refrigerant, a condenser for condensing the refrigerant discharged from the compressor, an expansion valve for adiabatically expanding the refrigerant condensed by the condenser, and an evaporator for evaporating the refrigerant. In addition, in a cooling cycle including a bypass passage that connects the discharge side and the suction side of the compressor, and a solenoid valve that opens and closes the bypass passage, the refrigerant outflow side of the evaporator and the suction side of the compressor are connected. A cooling cycle characterized in that a pressure adjusting means for preventing the pressure in the low-pressure passage from exceeding a predetermined pressure is provided on the low-pressure passage. 2. The cooling cycle according to claim 1, wherein the pressure adjusting means is a pressure release valve that opens at a pressure lower than the pressure resistance of the evaporator. 3. The pressure relief valve is 1.3 MPa [13
The cooling cycle according to claim 2, wherein the cooling cycle is opened at a pressure of at least Kg / cm ² ]. 4. The cooling cycle according to claim 1, wherein the pressure adjusting means is an accumulator.