JPH01210761A - Refrigerating device - Google Patents

Abstract

PURPOSE:To prevent a refrigerant from invading a compressor part and allow stable operation control at the time of the stop of compressor by providing check valves at a suction side pipeline and a discharge side pipeline of the compressor in a refrigerating device with which a high pressure chamber system compressor is equipped. CONSTITUTION:The refrigerating device forms a refrigerating cycle of a compressor 1a, a condenser 3, a receiver 4, a plurality of showcases 7-1, 7-2 and the main device of an accumulator 11. The compressor 1a is a displacement screw type or a displacement scroll type without a valve mechanism, a D-side check valve 2 and an S-side check valve 12 are attached to a discharge side pipeline and a suction side pipeline and during a stop the chamber of the compressor 1a is held high pressure. Further, the compressor 1a is equipped with a bypass pipe 14 for discharging the pressure of the chamber of the compressor 1a from the S-side check valve 12 to a low pressure side and a bypass electromagnetic valve 15 is provided on the halfway of the bypass pipe. A low pressure switch 13 is made comeback, an electromagnetic valve 15 is opened together with operation signals, a time-lag relay is turned on electricity and after a constant time the compressor 1a is operated.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a refrigeration system equipped with a high-pressure chamber type compressor, and particularly relates to a refrigeration system that has been improved so as to be able to operate in a stable state. be.

(Prior Art) According to the conventional art, in order to freeze a showcase or the like to a predetermined temperature range, the operation and stop of the compressor is generally controlled based on the pressure on the suction side of the compressor.

Regarding this type of control technology, Japanese Patent Publication No. 60-51021 is known.

FIG. 3 is a system diagram showing the refrigeration cycle of the above-mentioned known example;
1! ! I is its control circuit diagram.

Thermostats 17-1' and 17-2' (FIG. 4) are provided in the showcase 'Lx, 7-2 shown in FIG. 3, and each of these thermostats controls opening and closing of a liquid electromagnetic valve.

The above liquid solenoid valves are represented by 8-t and 8-2 in FIG.
The drawing reference numbers of the constituent parts shown in FIG. 4 are shown in parentheses (in the above example, they are indicated by 8-t' and 8-2'). Liquid solenoid valve 8-1.8-
2 (written as 8-t', 8-2')).

The compressor 1b (lb') has an electric circuit opened and closed by a low pressure switch 13 (13') provided in the suction pipe.
When the suction pressure becomes less than a predetermined value, the operation is stopped.

The temperature inside the showcase is thermostat 1'Lt'.

When the return temperature rises to 1'L2', the liquid solenoid valve 8-1 (
8-t'), 8-2 (8-2') is opened and the high-pressure liquid refrigerant flows to the low-pressure side showcase 'Lt, 7-2.

Due to the increase in suction pressure, compressor 1b (lb') starts operating. Each showcase 'Lt', 7-2 is independently operated by a solenoid valve l by a thermostat 1'Lt', 17-2'.
t (8-t') and 8-2 (8-2'), and the operation of the compressor 1b (lb') is controlled by changes in suction pressure. Since the compressors in the conventional examples described above are all of the low pressure chamber type, the operation control as described above is possible.

(Problem to be solved by the invention) However, when the compressor is of a high-pressure chamber type such as a screw type or scroll type, there are various problems that make it impossible to control the operation using the conventional refrigeration cycle configuration. , i.e.

When the operation is stopped, the pressure in the high pressure chamber flows into the low pressure side,
Even if the suction pressure is increased and the compressor stops, it will immediately start operating again.Also, since there is no valve on the high-pressure side pipe, refrigerant liquid may flow into the high-pressure chamber from the condenser. be.

SUMMARY OF THE INVENTION An object of the present invention is to provide a refrigerator that is improved so that stable operation control is possible even when a high-pressure chamber type compressor is used.

Means for Solving Problem C] The refrigerator of the present invention, which has been developed to achieve the above object, has the following features:
A check valve is provided in the suction side pipe line and the discharge side pipe line of the compressor 6. When carrying out the present invention, a check valve is only provided on either the suction side or the discharge side. However, although some effects may not be obtained, it is desirable to provide them on both the suction side and the discharge side.

Furthermore, as an embodiment of the present invention, it is recommended to provide a bypass pipe for balancing the pressures in the high pressure chamber and the low pressure (suction) side.

[Effect]

In a refrigerator with the above measures, check valves installed on the suction side and discharge side prevent (i) refrigerant liquid from flowing into the compressor chamber from the condenser side when the compressor is stopped; In addition, (...) the high-pressure gas in the compressor chamber does not flow to the low-pressure side and does not increase the suction pressure.

If the compressor is started after the high-pressure gas in the compressor chamber is released to the low-pressure side through the bypass pipe in response to the operation start signal, startup is easy and the compressor motor can be powered to a minimum. be. [Example] An example of the present invention will be described below with reference to FIGS. 1 and 2. Compressor 1a, condenser 3', liquid receiver 4゜Multiple showcase 'Lt, ? -2. The main equipment of the accumulator 11 forms a refrigeration cycle. As mentioned above, the compressor starts and stops depending on the load on the showcase side.
This is done by detecting low pressure with a low pressure switch 13.

The low pressure machine 1a is a positive displacement screw type or scroll type without a valve mechanism, and the discharge side (
Hereinafter, a check valve 2 (hereinafter abbreviated as the D side) is connected.

A check valve may be installed on the suction side (abbreviated as S side) to prevent liquid flow, but without the D check valve, the following problems will occur. The compressor does not have a valve on the D side, and the inside of the chamber is on the high pressure side, so liquid refrigerant may flow into the compressor 1a from the condenser 3 while the operation is stopped. There is a possibility that phenomena such as excessive foaming and oil leakage may occur that disturb the normal operation of the compressor 1a.

Further, even if a check valve is provided only on the D side, if there is no check valve on the S side, the following problems will occur. In other words, even if reverse rotation and backflow can be prevented with the D check valve 2, if the operation is controlled at low pressure in a showcase etc., each showcase 7-
1. Solenoid valve 8-t (8-t') is activated by thermostat ILt', 17-2' of 7-2.

8-2 (8-2') is turned ON and OFF, and when the low pressure switch 13 should be used to control the operation of the compressor 1a, when the operation is stopped, the high pressure side is controlled by the D check valve 2. Even if it is shut off, the high-pressure gas in the chamber of the compressor 1a flows back to the low-pressure side, the low-pressure pressure rises, and the low-pressure switch 13 returns to its original state, immediately returning to the operating state.
In this way, operation and stopping are repeated. In order to prevent this, an S-side check valve 12 is installed in this embodiment. In this embodiment, the D check valve 2 and the S side check valve 12 are installed.

While the compressor 1a is stopped, the chamber of the compressor 1a is kept at high pressure.
Furthermore, we must consider the following problem.

In the case of a positive displacement compressor without a valve mechanism, when starting from a state of high balance pressure.

The discharge pressure increases significantly depending on the volume ratio, and the motor output of the compressor 1a must be significantly increased to start the compressor, and the mechanical strength of the compression mechanism must also be increased. (
This problem does not necessarily occur with non-displacement pumps or positive displacement pumps with valve mechanisms).

Therefore, in this embodiment, a bypass pipe 14 is installed to release the pressure in the compressor chamber from the S side check valve 12 to the low pressure side, and a bypass solenoid valve 15 is installed in the middle of the bypass pipe 14. The low pressure switch 13 returns to operation and opens the bypass solenoid valve 15 along with the operation signal No. 4, releasing the pressure inside the compressor chamber to the low pressure side. When the bypass solenoid valve 15 is opened, the time-limited relay 16' is energized, and after a certain period of time has elapsed, the compressor 1a (la') is operated.

As explained above, according to this embodiment, in the case of a high-pressure chamber type compressor, when performing low-pressure pressure control operation, it is possible to reliably control the operation, and the output of the compressor motor can be reduced to the minimum necessary. Moreover, stable operation is possible without any unreasonable action being exerted on the compressor.

〔Effect of the invention〕

According to the present invention, it is possible to perform low-pressure control operation in the case of a high-pressure chamber type compressor, and to prevent refrigerant from entering the compressor while the compressor is stopped, preventing forming and oil drainage at startup. Prevention is possible. Furthermore, the capacity of the compressor motor can be reduced to the necessary minimum, and the required strength of the compressor components can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing an embodiment of the refrigeration cycle of the present invention, and FIG. 2 is an operating circuit diagram of the above embodiment. FIG. 3 is a system diagram of a conventional refrigeration cycle, and FIG. 4 is an operating circuit diagram of the conventional example. la, lb...compressor, 2...D check valve, 'L
+. 7-2...Showcase, 8-+, 8-2...Liquid solenoid valve, 12...S side check valve, 13...Low pressure switch, 14...Bypass pipe, 15...・Bypass solenoid valve,
la'...Magnetic contactor for compressor, 1a'...Magnetic compressor contact for compressor, lb'...Magnetic contactor for compressor, 8-1', 8-2'...Liquid solenoid valve. 13'...Low pressure switch, 15'...Bypass solenoid valve, 16'...Time-limiting relay, 17-1', 17-2
'···thermostat. Representative Patent Attorney Tadashi Akimoto Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1. (a) A refrigeration cycle comprising at least a refrigerant compressor, a condenser, an expansion valve, and an evaporator; (c) has means for detecting the suction pressure of the refrigerant gas, and (d) has a structure in which the suction pressure detected by the suction pressure detection means is a predetermined value. If it is less than that, the compressor is stopped;
In a refrigeration system equipped with automatic control means that operates the compressor if the value exceeds a predetermined value, (e) a check valve is provided in at least one of the suction system and the discharge system of the compressor. Characteristic refrigeration equipment. 2. (f) The above check valve is provided in both the suction side pipe line and the discharge side pipe line, (g) and (a) between both check valves, and (b) A low-pressure side line on the evaporator side than the suction side check valve is provided, (h) an electromagnetic on-off valve is interposed and connected to the bypass line, (i) further, (c) After stopping the operation of the compressor, when the suction pressure rises to a predetermined value, the electromagnetic on-off valve is opened, (d) when a set time has elapsed from the opening, the compressor is started to operate, (e) The refrigeration system according to claim 1, further comprising automatic control means for closing the electromagnetic on-off valve.