JPH08313076A - Refrigeration equipment - Google Patents

Abstract

PURPOSE: To avoid a problem of disabled operation or the like as caused by the operation of a low pressure breaker by securing a suction pressure above a fixed value immediately after a starting in the starting after a prolonged stoppage in a refrigerating apparatus set under low outdoor temperature conditions. CONSTITUTION: An upper part of a liquid receiver 3 is connected to a compressor 1 by a bypass piping 9 having a decompressor 8 and a solenoid valve 7 in the course thereof. A refrigerant gas of the liquid receiver 3 is introduced into a suction side of the compressor 1 below a fixed pressure for a fixed time length immediately after the starting. This can prevent abnormal drop in a suction pressure.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a refrigeration system.

[0002]

2. Description of the Related Art In a conventional device, as described in Japanese Patent Laid-Open No. 63-17356, the opening control of an electric expansion valve is performed as a means for keeping the suction pressure below a certain value, but the control is complicated. Therefore, microcomputer control is required and the cost is high.

[0003]

The prior art does not take into consideration the operating state when the condenser and the liquid receiver are installed in a place lower than the temperature condition in the chamber in which the evaporator is installed. If the compressor starts after the refrigeration system has stopped for a long time under the conditions, the internal pressure of the receiver and the internal pressure of the evaporator are reversed, so the refrigerant in the receiver is difficult to flow through the expansion valve to the evaporator side. Since the suction capacity of the compressor is higher than that of the compressor, the suction pressure may be abnormally reduced, and the compressor may stop due to the operation of the low-pressure pressure cutoff device and the cooling operation may become impossible. there were. As a countermeasure for this, conventionally, measures such as short-circuiting the low-voltage interrupting device to operate the device have been taken, but an unreasonable vacuum operation is performed, which is a reliability problem.

An object of the present invention is to ensure the minimum suction pressure necessary for the operation of the compressor regardless of the environmental temperature conditions in which the refrigeration system is installed.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention draws gas refrigerant in a receiver for a certain period of time immediately after starting the compressor by bypassing it to a compressor suction side at a constant pressure or less. An abnormal decrease in pressure is prevented to secure an operating pressure, and a high pressure side refrigerant liquid pressure is secured as the operating time elapses to create a stable operating state.

[0006]

In the refrigerating apparatus of the present invention, by connecting the upper part of the receiver with the suction side of the compressor, a depressurizing device for reducing the pressure to a certain pressure or less and a bypass pipe provided with a solenoid valve for a certain time at the same time when the compressor is started, The refrigerant gas in the upper part of the receiver is bypassed to the compressor suction side at a constant pressure or less.

As a result, the suction pressure of the compressor can be maintained at a certain pressure or higher even if the amount of refrigerant sucked from the evaporator is small, so that the operation can be performed without operating the low pressure cutoff device.

After a certain period of time, the bypass circuit is closed when the pressure of the liquid refrigerant on the high pressure side is secured by introducing the gas discharged from the compressor into the condenser, so that normal stable operation can be performed.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

In FIG. 1, a compressor 1, a condenser 2, a liquid receiver 3,
The expansion valve 4 and the evaporator 5 form a basic refrigeration cycle. Further, a bypass pipe having a solenoid valve 7 and a pressure reducing device 8 such as a constant pressure expansion valve or a volume adjusting valve capable of controlling the secondary side pressure below a certain level on the way between the upper part of the liquid receiver 3 and the suction side of the compressor 1. 9
It is tied with.

An electromagnetic valve 6 is provided in front of the expansion valve 4, and a low pressure cutoff device 10 that opens when the pressure falls below a set pressure is attached to the suction side of the compressor 1. With this structure, as shown in the control circuit of FIG. 2, in a normal cooling operation, the internal temperature controller 11 installed in the refrigerator 12 opens and closes the electromagnetic valve 6 installed in front of the expansion valve 4. The internal temperature is controlled, and when the compressor 1 is started, the internal temperature controller 11 is closed to open the solenoid valve 6,
The refrigerant is introduced into the evaporator 5, the suction pressure rises, and the low-pressure cutoff device 10 exceeds the set pressure and closes, whereby the compressor electromagnetic switch 1A is excited to start the operation. When stopped, the temperature controller 11 is opened to close the electromagnetic valve 6 and shut off the inflow of the refrigerant to the evaporator 5, thereby collecting the refrigerant in the liquid receiver 3 and reducing the suction pressure to reduce the pressure.
The compressor 1 stops when 0 is opened below the set pressure. With this control, when the condenser 2 and the liquid receiver 3 are installed at a temperature condition lower than the internal temperature of the refrigerator 12 in which the evaporator 5 is installed, the temperature controller 11 of the refrigerating device is operated depending on the operating conditions. Even if the solenoid valve 6 is opened by the operation command, the internal pressure of the liquid receiver 3 and the internal pressure of the evaporator 5 may be reversed at the boundary of the expansion valve 4 immediately after the operation. It becomes difficult to flow in to the compressor, and the compressor 1 tries to suck the refrigerant with a constant capacity so that the suction pressure is abnormally lowered. As a result, the refrigerant gas in the upper part of the liquid receiver 3 is introduced to the suction side of the compressor 1, so that the suction pressure can be maintained at a certain pressure or more, and the compressor 1 is stopped by the operation of the low pressure cutoff device 10. There is no such thing. By operating the compressor 1 for a certain period of time in this state, the refrigerant gas to which the amount of heat accompanying the operation of the compressor 1 is added is introduced into the condenser 2 and the condensation pressure and the receiver internal pressure can be gradually increased, Refrigerant can be introduced into the evaporator 5, and stable operation can be performed by ensuring the required suction pressure. The bypass solenoid valve 7 closes the bypass circuit by opening the contact 13B of the time-relay 13 and returns to the normal operation cycle after a certain time after the compressor 1 is started.

[0012]

According to the present invention, the condenser and the receiver of the refrigerating apparatus are installed in an environment of a temperature lower than that of the evaporator, and the gas in the receiver goes to the suction side of the compressor even in the operation after a long stop. By introducing the refrigerant by bypassing it, the suction pressure can be maintained above a certain level, and stable operation is possible.

Further, it is not necessary to short-circuit the low voltage circuit breaker.

[Brief description of drawings]

FIG. 1 is a system diagram of a refrigeration cycle showing an embodiment of the present invention.

FIG. 2 is a control circuit diagram showing an embodiment of the present invention.

[Explanation of symbols]

1 ... Compressor, 1A ... Electromagnetic switch for compressor, 2 ... Condenser,
3 ... Liquid receiver, 4 ... Expansion valve, 5 ... Evaporator, 6, 7 ... Electromagnetic valve, 8 ... Decompression device, 9 ... Bypass pipe, 10 ... Low pressure shutoff device, 11 ... Temperature controller, 12 ... Refrigerator, 13 … Time delay relay, 13B… Time delay relay contact.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ryosuke Tomita 390 Muramatsu, Shimizu City, Shizuoka Prefecture Within Hitachi Shimizu Engineering Co., Ltd.

Claims (1)

[Claims] 1. A refrigeration system comprising a compressor, a condenser, a liquid receiver, an expansion valve and an evaporator, and a bypass pipe provided with a pressure reducing device and a solenoid valve between the upper part of the liquid receiver and the suction pipe. Conclusion The compressor of the refrigeration system installed in a low outside air temperature condition operates by opening the solenoid valve for a certain period of time immediately after the compressor starts and bypassing the refrigerant gas in the receiver to the compressor suction side at a certain pressure or less. A refrigeration system characterized in that a necessary necessary suction pressure can be secured.