JPH08313073A - Refrigerating apparatus - Google Patents

Abstract

PURPOSE: To enhance a starting performance without loss in lubricating performance by connecting a discharge pipe, to a solenoid valve of a branch liquid pipe and a capillary tube by a connecting pipe having a capillary tube to reduce difference in pressure prior to the starting without the entry of an excessive liquid refrigerant into a compressor. CONSTITUTION: A discharge pipe 2 is connected to a branch liquid pipe 9 by a link pipe 12 through a capillary tube 13. A gas refrigerant on the high pressure side enters a branch liquid pipe 9 via the capillary tube 13 and flows into a compressor 1 via a capillary tube 11 of the branch liquid pipe 9, reaching the suction side of the compressor 1. With the inflow of the gas refrigerant on the high pressure side, the pressure on the suction side of the compressor 1 rises, but the high pressure gas refrigerant will not reach an evaporator 6 with the action of a check valve 8. The inflow of the gas refrigerant causes the pressure on the suction side of the compressor 1 to rise until reaching a level the same as that on the discharge side. At this point, the inflow of the gas refrigerant stops.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigeration system.

[0002]

2. Description of the Related Art FIG. 2 shows a refrigerant circuit of a conventional refrigeration system. In the figure, 1 is a compressor, 2 is a discharge pipe of the compressor,
3 is a condenser connected to the discharge pipe, 4 is a liquid pipe connected to the condenser, 5 is an evaporator connected to the liquid pipe, 7 is a suction pipe connected to the evaporator, and this suction pipe is a check valve 8 It is connected to the compressor through. Reference numeral 5a is a pressure equalizing pipe connected to the expansion valve 5 for detecting the outlet pressure of the evaporator, and 5b is a temperature-sensitive tube connected to the expansion valve 5 for measuring the outlet temperature of the evaporator 6. Reference numeral 9 is a branch liquid pipe which is separated from the liquid pipe and returns to the compressor 1, and 11 is a capillary tube provided in the branch liquid pipe.

In the above apparatus, the high temperature and high pressure gas refrigerant discharged from the compressor 1 enters the condenser 3 via the discharge pipe 2. Here, it is condensed and liquefied and enters the liquid pipe 4. Here, most of the refrigerant is decompressed by the expansion valve 5 and enters the evaporator 6. In the evaporator 6, heat is taken from the surroundings, and the refrigerant itself evaporates and vaporizes. The expansion valve 5 detects the evaporator outlet pressure by the pressure equalizing pipe 5a, detects the evaporator outlet temperature by the temperature sensing cylinder 5b, and adjusts the throttle so that the heating degree of the outlet portion of the evaporator 6 becomes constant. ing. The gas refrigerant that has left the evaporator 6 returns from the suction pipe 7 through the check valve 8 to the compressor 1 to complete the refrigeration cycle.

During this time, the refrigerant branched from the liquid pipe 4 is flown through the branch liquid pipe 9 and the flow rate is adjusted by the capillary tube 11 and then injected into the intermediate pressure portion inside the compressor to lower the temperature of the refrigerant during compression. When the medium cooled by the evaporator 6 such as air is cooled to a predetermined temperature by the action of the refrigerating device, the compressor 1 is stopped. When the compressor 1 is stopped, the temperature at the outlet of the evaporator 6 and the saturation temperature of the pressure become the same as the temperature of the air flowing through the evaporator 6. Since the expansion valve 5 has a low degree of superheat, the expansion valve 5 is closed and closed. On the other hand, the liquid refrigerant flowing from the branch liquid pipe 9 into the compressor 1 through the capillary tube 11 continues to flow because the pressure on the suction side of the compressor 1 is low. Although the pressure on the suction side of the compressor 1 rises as the refrigerant flows, the check valve 8 prevents the refrigerant from flowing into the evaporator 6. Due to this inflow, the pressure on the suction side of the compressor 1 rises to the same pressure as the pressure on the condenser 3 part, that is, the discharge side of the compressor 1, and the inflow is stopped at this point. When the temperature of the air flowing through the evaporator 6 rises, the compressor 1 starts operating again. At this time, since the pressure on the suction side and the pressure on the discharge side of the compressor 1 are the same, starting is easy. After that, the temperature of the air flowing through the evaporator 6 is kept constant by repeating this process.

In the case of this refrigerant circuit, the branch liquid pipe 9
Since the liquid refrigerant flows inside the compressor 1 and further flows into the suction side thereof, a large amount of liquid refrigerant exists in the compressor portion when the operation of the compressor 1 is started. Therefore, when the operation and the stop are repeated in a short time, a large amount of the liquid refrigerant enters the lubricating oil in the compressor 1 and the lubricity thereof is impaired.

FIG. 3 is a refrigerant circuit diagram of another example of the conventional refrigerating apparatus. This is a refrigerant circuit for avoiding impairing lubricity in the above-mentioned example. In this example, a solenoid valve 10 is provided in the portion of the branch liquid pipe 9 of the refrigerating apparatus shown in FIG. 2, and the other portions are the same as those in FIG. The solenoid valve 10 is opened during the operation of the compressor 1 and is closed when the compressor 1 is stopped. Therefore, the operation during operation of the compressor 1 is the same as in the case of FIG. Similarly, the expansion valve 5 is closed when the compressor 1 is stopped. On the other hand, since the solenoid valve 10 is closed, it flows through the branch liquid pipe 9,
The liquid refrigerant will not flow into the compressor 1. Therefore, as in the example shown in FIG. 2, it can be avoided that a large amount of liquid refrigerant enters the lubricating oil in the compressor 1 and impairs its lubricity. However, since the refrigerant on the high pressure side does not flow into the suction side of the compressor 1 during the stop, the pressure in this portion also does not rise during this period. Therefore, when the compressor 1 is operated again, the pressure difference between the suction side and the discharge side of the compressor remains, and the compressor cannot be started if the pressure is excessive.

[0007]

In the prior art, as shown in FIG. 2, when the injection circuit is opened to eliminate the pressure difference between the high pressure and the low pressure of the compressor while the compressor is stopped, the excess liquid refrigerant is discharged. May enter the compressor, impair lubricity, and lead to bearing damage. To prevent this, an injection valve is provided in the injection circuit as shown in FIG. 3 so that it is closed at least while the compressor is stopped, so that the refrigerant on the high pressure side moves to the low pressure side of the compressor while the compressor is stopped. It becomes impossible to do so, and the differential pressure at the time of starting becomes large and the starting performance deteriorates.

The present invention solves the above-mentioned drawbacks of the prior art,
It is an object of the present invention to reduce the high / low pressure difference before starting without introducing an excessive amount of liquid refrigerant into the compressor, to improve the startability without impairing lubricity.

[0009]

SUMMARY OF THE INVENTION The present invention solves the above problems and relates to a refrigerating apparatus having the following features. (1) A refrigeration cycle is composed of a compressor, a condenser, a throttle mechanism, and an evaporator, and a refrigerant circuit between the condenser and the throttle mechanism branches to open when the compressor is operated or stopped.
In the refrigerating apparatus having an injection circuit for injecting a part of the liquid refrigerant into the compressor through an on-off valve and a throttle that are closed, a high-pressure gas section in the refrigeration cycle,
A high pressure gas circuit having a throttle was provided between the on-off valve and the throttle of the injection circuit. (2) In the refrigerating apparatus according to the above item (1), the high pressure gas portion is a discharge gas circuit that connects between the compressor and the condenser. (3) In the refrigerating apparatus according to the above item (1), in the case where the outlet side of the condenser is provided with a liquid receiver, the high-pressure gas portion is set as the gas region of the liquid receiver. (4) A refrigeration cycle is constructed by connecting a compressor, a condenser, a temperature automatic expansion valve, an evaporator, and a check valve in this order, and a refrigerant circuit between the condenser and the temperature automatic expansion valve. In a refrigerating apparatus having an injection circuit for injecting a part of the liquid refrigerant into the compression chamber in the middle of compression of the compressor, the electromagnetic valve and the capillary tube opened and closed by the operation of the compressor, the compressor being branched, A high-pressure gas circuit having a capillary tube was provided between the discharge gas circuit in the refrigeration cycle, the electromagnetic valve of the injection circuit, and the capillary tube.

[0010]

In the refrigerating apparatus of the present invention, a high pressure gas section,
A connecting pipe having a throttle is provided between the on-off valve of the injection circuit section and the throttle. During operation of the compressor, the connection part on the injection circuit side is a high pressure part before being throttled. Therefore, due to the restriction provided in this connecting pipe, the amount of the gas refrigerant flowing to the injection portion is limited. That is, the injection flow rate is not significantly affected.

On the other hand, when the compressor is stopped, the open / close valve of the injection circuit is closed. The injection circuit communicates with the intermediate pressure section inside the compressor, but there is no valve between it and the suction side, so high-pressure gas refrigerant enters the compressor through the throttle of the injection circuit from the connecting pipe, and , To the suction pipe. Since there is a check valve in the suction pipe,
Since it does not reach the evaporator portion, the pressure in the suction pipe portion rises in a short time, and the difference from the high pressure decreases. Since the liquid refrigerant does not flow in during this period, the oil of the compressor is not diluted with the refrigerant, and the startability is improved.

[0012]

1 is a refrigerant circuit diagram of a refrigerating apparatus according to an embodiment of the present invention. In the figure, 12 is a connecting pipe that connects the discharge pipe 2, the electromagnetic valve 10 of the branch liquid pipe 9 and the capillary tube 11, and 13 is a capillary tube provided in the connecting pipe. The parts other than the above are the same as those of the prior art circuit shown in FIG.

In the circuit of this embodiment, when the compressor 1 is in operation, the solenoid valve 10 is open and the discharge pipe 2
Since the branch liquid pipe 9 is also on the high pressure side, there is almost no pressure difference between both ends of the capillary tube 13. Therefore, the operation is the same as that of the circuit of FIG. 2 shown in the related art. It is the same that the expansion valve 5 closes when the compressor 1 stops. The electromagnetic valve 10 is closed when the compressor 1 is stopped, as in the example of FIG. However, since the discharge pipe 2 and the branch liquid pipe 9 are connected via the capillary tube 13, the gas refrigerant on the high pressure side flows into the branch liquid pipe 9 through the capillary tube 13 and then through the capillary tube 11 to the compressor. 1 to the suction side of the compressor 1.

Although the pressure on the suction side of the compressor 1 rises due to the inflow of the gas refrigerant on the high pressure side, the check valve 8
This high pressure gas refrigerant does not reach the evaporator 6. Due to the inflow of the gas refrigerant, the pressure on the suction side of the compressor 1 rises until it becomes the same as the pressure on the discharge side, and the inflow is stopped at this point. It is the same as the conventional example that the compressor 1 restarts operation when the temperature of the air flowing through the evaporator 6 rises.

In this embodiment, the discharge pipe is used to take out the high-pressure gas. However, in a refrigerating apparatus having a liquid receiver, it may be taken from the gas portion such as the upper end portion, and becomes the gas portion when stopped. Any one may be used as long as it is on the high pressure side. In this embodiment, a hot gas bypass and a reverse cycle type defrosting device having a four-way valve are not shown, but those having these can be similarly applied.

As described in detail above, in the refrigeration system of this embodiment, the on-off valve of the injection circuit and the throttle are connected by the high pressure side gas refrigerant portion and the connecting pipe having the throttle. During operation of the compressor, the gas refrigerant hardly enters the injection circuit, and the cooling effect of the injection circuit is not impaired. When the compressor 1 is stopped, the high-pressure gas refrigerant is supplied to the compressor 1
Since it can reach the suction side via the inside of the, it is possible to eliminate the pressure difference from the discharge side before the activation and facilitate the activation. Further, since the liquid refrigerant does not flow in, it is possible to avoid adversely affecting the lubricity of the compressor.

Although not shown, the same effect can be obtained by connecting the discharge side and the suction side of the compressor 1 via an open / close valve and opening the open / close valve at the time of stoppage. Therefore, this embodiment is advantageous in that it can be manufactured at a lower cost.

[0018]

In the refrigerating apparatus of the present invention, the high-pressure gas circuit having the throttle is provided between the high-pressure gas portion in the refrigeration cycle and the on-off valve and throttle of the injection circuit, so that lubricity is impaired. The startability can be improved without

[Brief description of drawings]

FIG. 1 is a refrigerant circuit diagram of a refrigerating apparatus according to an embodiment of the present invention.

FIG. 2 is a refrigerant circuit diagram of a first example of a conventional refrigeration system.

FIG. 3 is a refrigerant circuit diagram of a second example of a conventional refrigeration system.

[Explanation of symbols]

 1 Compressor 2 Discharge pipe 3 Condenser 5 Expansion valve 6 Evaporator 8 Check valve 9 Branch liquid pipe 10 Electromagnetic valve 11 Capillary tube 12 Connecting pipe 13 Capillary tube

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Takahiro Sasaki 3-1, Asahimachi, Nishibiwajima-cho, Nishikasugai-gun, Aichi Prefecture Mitsubishi Heavy Industries, Ltd. Air Conditioning Factory

Claims (4)

[Claims] 1. A compressor, a condenser, a throttle mechanism, and an evaporator constitute a refrigeration cycle, and a refrigerant circuit between the condenser and the throttle mechanism branches to open and close the compressor by operating and stopping it. In a refrigerating apparatus including an injection circuit for injecting a part of the liquid refrigerant into a compressor via an on-off valve and a throttle, the high-pressure gas portion in the refrigeration cycle, and between the on-off valve and the throttle of the injection circuit. A refrigeration system provided with a high-pressure gas circuit having a throttle. 2. The refrigerating apparatus according to claim 1, wherein the high-pressure gas section is a discharge gas circuit connecting between the compressor and the condenser. 3. The refrigerating apparatus according to claim 1, wherein in the case where the condenser is provided with a liquid receiver on the outlet side, the high-pressure gas portion is a gas region of the liquid receiver. 4. A refrigeration cycle is constructed by connecting a compressor, a condenser, a temperature-type automatic expansion valve, an evaporator, and a check valve in this order to form a refrigeration cycle, and between the condenser and the temperature-type automatic expansion valve. In a refrigeration system equipped with an injection circuit that branches from a refrigerant circuit, opens and closes when the compressor is operated and stopped, and a capillary tube, and injects part of the liquid refrigerant into the compression chamber during compression of the compressor. A high-pressure gas circuit having a capillary tube is provided between the discharge gas circuit in the refrigeration cycle and the solenoid valve of the injection circuit and the capillary tube.