JPH109690A - Refrigerator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the entrapping of the liquid refrigerant to a compressor and the liquid compression in starting the compressor without using an accumulator by intermittently opening/closing a solenoid valve for the suction piping for the prescribed period of time until the liquid return is eliminated in starting the compressor, and opening a solenoid valve for bypass. SOLUTION: A discharge pipe 3 to connect a compressor 1 to a condenser 4 is connected to a suction piping 9 to connect a solenoid valve 11 for the suction piping to the compressor 1 through a bypass circuit 12, and a solenoid valve 13 for bypass is interposed in the bypass circuit 12. The solenoid valve 11 is intermittently opened/closed until the liquid return to the compressor 1 is eliminated when the compressor 1 is started, and then, the solenoid valve 11 is opened. The solenoid valve 13 is opened while the solenoid valve 11 is intermittently opened/closed, and the amount of the sucked refrigerant returning from an evaporator 8 to the compressor 1 is reduced thereby, and the liquid refrigerant contained in the sucked refrigerant is heated and vaporized to prevent the liquid compression in stating the compressor 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to prevention of stagnation of liquid refrigerant in a compressor of a refrigeration system and prevention of liquid return when the compressor is started.

[0002]

2. Description of the Related Art Conventionally, various proposals have been made regarding prevention of stagnation of liquid refrigerant in a compressor and prevention of liquid compression due to liquid return when the compressor is started. For example, Japanese Patent Publication No. 2-26146 discloses a bypass circuit provided from a discharge pipe to an accumulator (referred to as a receiver in this publication). During a predetermined time, the solenoid on-off valve is opened, the discharge gas is bypassed, and the discharge gas exchanges heat with the suction pipe to prevent liquid compression at the time of starting the compressor.

[0003] Further, in Japanese Patent Application Laid-Open No. 62-252853, an on-off valve is provided in a liquid line, and at the same time as the compressor is stopped, this on-off valve is closed. By closing the on-off valve until the low pressure becomes equal to or less than the set value, liquid compression at the time of starting the compressor is prevented.

In the compressor disclosed in Japanese Utility Model Laid-Open Publication No. 61-71864, an on-off valve for opening and closing the suction and discharge circuits according to the temperature of refrigerant gas is provided in the suction and discharge circuits of the compressor. , The flow of the refrigerant gas is stopped on both the high-pressure side and the low-pressure side, thereby preventing the refrigerant from stagnation into the compressor.

[0005] Further, in the apparatus disclosed in Japanese Utility Model Laid-Open No. 1-109758, a check valve is provided on the discharge side of the compressor and a pressure on-off valve is provided on the suction side of the compressor. The valve prevents backflow of the refrigerant from the condenser to the compressor, and automatically closes the suction-side pressure on / off valve due to a change in pressure, thereby preventing refrigerant from stagnation into the compressor.

[0006]

However, such a conventional refrigeration system has the following problems. (1) In Japanese Patent Publication No. 2-26146, when the amount of liquid returned at the time of starting the compressor is large, prevention of liquid compression is insufficient and a large accumulator is required. Also, it is not possible to prevent liquid stagnation in the compressor. (2) In Japanese Patent Application Laid-Open No. 62-252853, the amount of liquid returned at the start of the compressor is not directly related to the low pressure, and there is no means for heating the liquid returning to the compressor. Can not. In addition, it is not possible to prevent stagnation of the liquid in the compressor. (3) Japanese Utility Model Application 61-71864 and Japanese Utility Model Application 1-1097
In 58, it is possible to prevent liquid stagnation in the compressor, but it is not possible to prevent liquid return when the compressor is started.

As described above, in the conventional refrigeration system,
There was a drawback that it was not possible to prevent liquid stagnation in the compressor without an accumulator and prevent liquid compression due to liquid return when the compressor was started. The present invention has been made in view of the problems existing in such a conventional technology, and aims at preventing the stagnation of the liquid refrigerant into the compressor without using an accumulator, In addition, liquid compression at the time of starting the compressor is prevented.

[0008]

In order to achieve the above object, according to the present invention, a check valve for allowing a refrigerant flow only in a discharge direction to a discharge pipe of a compressor is provided. A solenoid valve for a suction pipe is provided in each suction pipe, and a solenoid valve for a bypass is provided from the discharge pipe between the check valve and the compressor to the suction pipe between the solenoid valve for the suction pipe and the compressor. When the compressor is stopped, the suction pipe solenoid valve is closed, and when the compressor is started, the suction pipe solenoid valve is closed for a predetermined time until liquid return to the compressor is eliminated. A controller is provided for opening and closing the solenoid valve intermittently, opening the solenoid valve for bypass, opening the solenoid valve for the suction pipe after the lapse of the predetermined time, and closing the solenoid valve for bypass.

According to the second aspect of the present invention, any one of the operation time after starting the compressor, the degree of superheat of the suction refrigerant gas, the temperature of the discharge refrigerant gas, the degree of oil dilution, and the oil level in the compressor is determined. When the detected value reaches a predetermined value, the elapse of the predetermined time is detected.

Therefore, in the refrigeration system configured as described above, when the compressor is stopped, the check valve provided on the discharge pipe of the compressor and the solenoid valve for the suction pipe provided on the suction pipe are closed. Thereby, the refrigerant in the refrigerant circuit is held by the condenser, the evaporator, and the like, and the stagnation of the liquid refrigerant into the compressor is prevented.

When the compressor is started, the solenoid valve for the suction pipe is opened and closed intermittently for a predetermined time until the liquid return is eliminated, so that the amount of liquid refrigerant returning from the refrigerant circuit to the compressor is reduced. You. Furthermore, during the predetermined time, the bypass solenoid valve is opened, the discharge gas is bypassed to the suction pipe, mixed with the refrigerant sucked into the compressor, and heats the refrigerant.
Liquid return to the compressor is prevented.

Further, since the liquid refrigerant returns to the compressor only at the beginning of the storage of the liquid refrigerant on the suction side of the refrigerant circuit, the predetermined time until the liquid return is eliminated may be various times. It can be a time when the operating value reaches a predetermined value experimentally obtained, the operating time after starting the compressor, the degree of superheat of the suction refrigerant gas, the temperature of the discharged refrigerant gas, the degree of dilution of the oil, the oil of the compressor Using the change in height or the like, any one of these is detected.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is embodied in a refrigerating apparatus will be described in detail with reference to FIGS. FIG. 1 is a refrigerant circuit diagram of the present embodiment, and FIG.
5 is a control time chart of the solenoid valve in the refrigerant circuit described in FIG.

In FIG. 1, a compressor 1, a check valve 2, a condenser 4, a receiver 5, a temperature-sensitive expansion valve 7, an evaporator 8, and a solenoid valve 11 for a suction pipe are sequentially connected to form a refrigerant circuit. .
In the refrigerant circuit, reference numeral 3 denotes a discharge pipe connecting the compressor 1 and the condenser 4, and the above-mentioned check valve 2 is provided on the way. Reference numeral 9 denotes a suction pipe for connecting the evaporator 8 and the compressor 1, and the above-described solenoid valve 11 for the suction pipe is provided on the way.

In the above refrigerant circuit, the compressor 1
From the discharge pipe 3 connecting the suction valve and the check valve 2 to the solenoid valve 1 for the suction pipe.
A bypass circuit 12 is connected to a suction pipe 9 connecting the compressor 1 and the compressor 1, and a bypass solenoid valve 13 is provided in the bypass circuit 12. Reference numeral 14 denotes a controller, which controls the start / stop of the compressor 1 and the opening / closing of the intake pipe solenoid valve 11 and the bypass solenoid valve 13.

The solenoid valve 11 for the suction pipe and the solenoid valve 13 for the bypass in the refrigerant circuit are controlled as shown in the control time chart shown in FIG. That is, the compressor 1
With the stop of the operation, the controller 14 sets the solenoid valve 1 for the suction pipe.
1 is closed. Therefore, while the compressor 1 is stopped, the ambient temperature of the condenser 4, the receiver 5, and the evaporator 8 becomes higher than the ambient temperature of the compressor 1, and the refrigerant pressure in these devices 4, 5, and 8 rises, Even if the refrigerant attempts to move into the compressor 1, the refrigerant flows into the compressor 1 because the solenoid valve 11 for the suction pipe is closed and the check valve 2 is closed by the refrigerant pressure. The phenomenon of moving and storing, that is, liquid stagnation does not occur.

When the compressor 1 is started, the controller 14 opens and closes the intake pipe solenoid valve 11 intermittently for a predetermined time until the liquid return to the compressor 1 is eliminated. Open the valve. On the other hand, the bypass solenoid valve 13
Is opened while the intake pipe solenoid valve 11 is intermittently opened and closed, and then closed simultaneously with the opening of the suction pipe solenoid valve 11. Therefore, the amount of the suction refrigerant returning to the compressor 1 from the evaporator 8 is reduced, and the suction refrigerant mixes with the discharge gas flowing from the bypass circuit 12 into the suction pipe 9 and is heated. Even if the refrigerant contains a liquid refrigerant, the liquid refrigerant is heated and vaporized, so that no liquid compression occurs when the compressor 1 is started.

In the above description, the return of the liquid to the compressor 1 is continued until the liquid refrigerant remaining on the suction side of the refrigerant circuit is almost exhausted, and decreases with the elapse of the operation time after the start of the compressor 1. I do. Therefore, in order to detect the elapse of a predetermined time until the liquid return to the compressor 1 is canceled, various operation values are first obtained as follows. (1) The time until the liquid returns to zero is determined experimentally in advance in consideration of the change in the operating condition. (2) When the liquid refrigerant returns, the suction refrigerant gas is not overheated, and thus the discharge gas temperature is low. Therefore, the temperature at which the return of the liquid refrigerant stops is determined in advance by an experiment. (3) When the liquid refrigerant returns to the compressor 1, the liquid refrigerant dissolves into the lubricating oil stored in the crankcase in the compressor 1, the oil level rises, and the lubricating oil is also diluted. By paying attention to these changes, an oil level or a dilution degree of the lubricating oil when the return of the liquid refrigerant is lost is determined in advance by an experiment.
Then, any one of these various values during the actual operation, that is, the operation time after starting the compressor, the degree of superheat of the suction refrigerant gas, the temperature of the discharge refrigerant gas, the degree of dilution of the oil, the oil level in the compressor Any one of the heights is detected, and when the detected value reaches a predetermined value, it is determined that the predetermined time has been reached, and the elapse of the predetermined time can be detected.

[0019]

Since the present invention is configured as described above, it has the following effects. (1) A check valve is provided in the discharge pipe of the compressor, and a solenoid valve for the suction pipe is provided in the suction pipe, and the solenoid valve for the suction pipe is closed by the controller when the compressor 1 is stopped. The refrigerant in the refrigerant circuit during stoppage is confined, held in a condenser, an evaporator, and the like, to prevent liquid from stagnating in the compressor. (2) Compressor 1 is provided with bypass circuit 12, bypass solenoid valve 13, suction pipe solenoid valve 11, and controller 14.
At the time of startup, the intake pipe solenoid valve 11 is opened and closed intermittently for a predetermined time until the liquid returns to zero, the bypass solenoid valve 13 is opened, and after the predetermined time has elapsed, the suction pipe solenoid valve is opened. Since the solenoid valve is closed, the return of liquid to the compressor is suppressed by opening and closing the suction pipe solenoid valve, and the suction gas is mixed with the discharge gas flowing from the bypass circuit into the suction pipe and heated. Since the liquid refrigerant in the refrigerant is vaporized, liquid compression at the time of starting the compressor is prevented.
Further, an accumulator can be dispensed with.

[Brief description of the drawings]

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

FIG. 2 is a control time chart of an electromagnetic valve in the refrigerant circuit of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Compressor 2 Check valve 3 Discharge pipe 4 Condenser 7 Temperature-sensitive expansion valve as a throttle mechanism 8 Evaporator 9 Suction pipe 11 Suction pipe solenoid valve 12 Bypass circuit 13 Bypass solenoid valve 14 Controller

Claims (2)

[Claims] 1. A check valve for allowing a refrigerant flow only in a discharge direction is provided in a discharge pipe of a compressor, and a solenoid valve for a suction pipe is provided in a suction pipe of the compressor, respectively, and the check valve and the compressor are provided. A bypass circuit having a bypass solenoid valve is provided from the discharge pipe between the suction pipe and the suction pipe between the suction pipe solenoid valve and the compressor, and the suction pipe solenoid valve is closed when the compressor is stopped. When the compressor is started, the solenoid valve for the suction pipe is intermittently opened and closed for a predetermined time until the liquid return to the compressor is eliminated, and the solenoid valve for the bypass is opened for the predetermined time. A refrigeration apparatus comprising: a controller that opens the solenoid valve for the suction pipe after the elapse and closes the solenoid valve for the bypass. 2. Detecting any one of an operation time after starting the compressor, a degree of superheating of the suctioned refrigerant gas, a temperature of the discharged refrigerant gas, a degree of oil dilution, and an oil level in the compressor. 2. The refrigeration apparatus according to claim 1, wherein when the predetermined time elapses, the elapsed time of the predetermined time is detected.