JP3425278B2 - refrigerator - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerator (including a heat pump in the present specification) having a flow rate control valve provided between a compressor and an evaporator.

[0002]

2. Description of the Related Art Conventionally, a refrigerator shown in FIG. 4 is known (Japanese Patent Laid-Open No. 6-229631). This refrigerator has a closed loop of a refrigerant including a compressor 11, a condenser 12, an expansion valve 13, an evaporator 14 and a flow rate control valve 15 as a suction valve, and a bypass valve 16 whose opening degree can be adjusted.
And a bypass flow path 17 for adjusting the capacity that connects the discharge side and the suction side of the.

A temperature detector 18 is provided in the evaporator 14 so as to detect the refrigerant temperature, and a pressure detector 19 detects a refrigerant pressure between the bypass passage 17 and the confluence portion of the closed loop of the refrigerant and the compressor 11. It is possible. Further, the control means 20, which is a programmable computer, has a temperature detector 1
8 receives a temperature signal from the pressure detector 19 and a pressure signal from the pressure detector 19, calculates the first pressure in the evaporator 14 from the temperature signal, and outputs the first pressure and the second pressure indicated by the pressure signal. The bypass valve 16 is formed to perform the following control based on the pressure.

At the time of starting the refrigerator, the control means 20 keeps the flow control valve 15 closed and the bypass valve 16 kept open so that the refrigerant gas discharged from the compressor 11 is bypassed. A bypass operation of directly leading to the suction port of the compressor 11 through 17 is performed to increase the pressure on the suction side of the compressor 11. The pressure on the suction side of the compressor 11 during the bypass operation can be adjusted by opening and closing the bypass valve 16. Then, the control means 20 compares the first pressure and the second pressure. When the second pressure is higher than the first pressure, the flow rate of the refrigerant flowing through the evaporator is slow, so that the liquid back Since the possibility of occurrence of the phenomenon is extremely low, the flow rate control valve 15 is opened and the bypass valve 16 is closed.

On the contrary, when the second pressure is lower than the first pressure, the liquid back phenomenon is likely to occur, so that the flow control valve 15 is kept closed to continue the bypass operation and to bypass the bypass operation. The second pressure is increased by opening and closing valve 16. In this operating state, when the first pressure exceeds the upper limit value of the second pressure that can be increased by the bypass operation, the bypass operation is continued with the flow rate control valve 15 slightly opened, and the first pressure is increased. When the first pressure is lowered or becomes equal to or lower than the second pressure, the flow rate control valve 14 is gradually opened, for example, over about 60 seconds, and the bypass valve 16 is gradually opened. Close it.

In this way, the compressor 11 does not suck the refrigerant liquid flowing out from the evaporator 14 together with the refrigerant gas,
That is, the temperature detector 18 is provided so that the liquid back phenomenon does not occur.
(It may be a pressure detector), a pressure detector 19 and a control means 20 are provided to control the pressure between the evaporator 14 and the flow rate control valve 15 and the pressure between the flow rate control valve 15 and the compressor 11. It is designed to maintain balance. The higher the pressure on the evaporator 14 side of the flow rate control valve 15 becomes higher than the pressure on the compressor 11 side, the faster the flow rate of the refrigerant flowing through the flow rate control valve 15 becomes, and the faster the flow rate of the refrigerant evaporates to the refrigerant gas. The refrigerant liquid in the container 14 is mixed. That is, the pressure between the flow control valve 15 and the compressor 11 is adjusted by opening and closing the bypass valve 16, and this pressure becomes equal to or higher than the pressure between the evaporator 14 and the flow control valve 15. At this time, the flow rate control valve 15 is opened to slow the flow rate of the refrigerant flowing through the flow rate control valve 15 to prevent liquid back.

[0007]

In the conventional refrigerating machine described above, the installation of the bypass valve 16 is indispensable, and the bypass valve 16 is in an operating state when it is open. The operation with the bypass valve 16 open means that the refrigerant to be heat-exchanged is directly returned to the compressor 11 without passing through the evaporator 14, causing a loss of power and the flow control valve 15 Will open and the time required for the refrigerator to fully demonstrate its capabilities will be prolonged. When the compressor 11 is an oil-cooled type, by increasing the pressure between the flow rate control valve 15 and the compressor 11, this pressure is higher than the pressure of oil for lubricating or cooling the compressor 11. Therefore, a problem that oil cannot be injected into the compressor 11, that is, a phenomenon of oil injection failure occurs. The present invention has been made to solve such conventional problems, to reduce the loss of power and to prevent the occurrence of liquid back phenomenon, further in the case of the oil-cooled compressor of the phenomenon of poor lubrication It is intended to provide a refrigerator that can prevent the generation of the refrigerator.

[0008]

In order to solve the above-mentioned problems, the first aspect of the present invention is to provide at least a compressor, a condenser, an expansion valve,
In a refrigerator provided with a closed loop of a refrigerant including an evaporator and a flow rate control valve, a pressure detector for detecting the pressure of the refrigerant gas sucked in by the compressor, and a range in which the flow rate control valve can be controlled before starting the compressor. Keep the minimum opening, and after starting the compressor, gradually open the flow control valve if the pressure detected by the pressure detector is lower than the set value.In other cases, the flow control valve is opened. And a control means having a function of holding the opening degree of.

According to a second aspect of the present invention, a temperature or pressure detector is provided in the refrigerant flow passage portion between the evaporator and the flow rate control valve, and the control means is provided with a signal from the temperature or pressure detector. The refrigerant flow rate value in the flow rate control valve is calculated from the pressure of the refrigerant flow path portion obtained based on the pressure of the suction refrigerant gas and the opening degree of the flow rate control valve, and the refrigerant flow rate value is smaller than the allowable value. In this case, it is also provided with a function of increasing the opening degree of the flow rate control valve immediately after the compressor is started within a range in which the refrigerant flow rate value does not exceed the allowable value.

Further, according to a third aspect of the present invention, the evaporator is provided with a liquid level gauge for detecting the liquid level of the refrigerant liquid therein, and the control means is provided when the liquid level detected by the liquid level gauge is high. Has a function of reducing the opening of the expansion valve.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a refrigerator according to the first aspect of the present invention, which is different from the refrigerator shown in FIG. 4 in that a bypass valve 16, a bypass flow path 17 and a temperature detector 18 are omitted, and a pressure detector 19 is used instead of the control means 20. Except that a control means 1 for adjusting the opening degree of the flow rate control valve 15 in response to the pressure signal is newly provided, and the portions corresponding to each other are designated by the same reference numerals. Omit it.

In the case of this refrigerator, the control means 1 starts the flow rate control valve by opening it by the minimum opening degree within a controllable range from the closed state. Compressor 11
When the pressure detected by the pressure detector 19 is lower than the set value, the control means 1 gradually opens the flow rate control valve 15 after the start of, and in other cases, the opening degree of the flow rate control valve 15 is changed. It is formed to hold. Therefore, even when the pressure in the evaporator 14 is high when the compressor 11 is started, the pressure between the compressor 11 and the compressor 11 is constantly adjusted by the flow control valve 15, and the suction gas of the compressor 11 is also adjusted. Since the amount and the amount of gas flowing through the flow control valve 15 are equal, the evaporator 14
The flow velocity of the gas flowing in the chamber is also slowed down, and the possibility of the liquid back phenomenon occurring is significantly reduced. Further, in this state, even if the compressor 11 is of an oil cooling type, it is operated at a suction pressure that does not cause a phenomenon of poor lubrication of the compressor 11. Then, when the operation is continued in this state, the pressure of the evaporator 14 gradually decreases.

In accordance with this, the temperature of the evaporator 14 decreases, so that the pressure between the flow rate adjusting valve 15 and the compressor 11 is made higher than the pressure between the evaporator 14 and the flow rate adjusting valve 15. It is possible to prevent the occurrence of the liquid back phenomenon without performing the operation of. Further, the temperature inside the evaporator 14 can be lowered early. Further, when the liquid is excessively accumulated in the evaporator 14, it is conventionally necessary to drain the liquid in order to avoid the liquid back phenomenon, but in this example, the pressure of the evaporator 14 is lowered. Since the liquid in the evaporator 14 can be evaporated in the process, the work for draining the liquid is also unnecessary. Next, the pressure inside the evaporator 14 is controlled by the flow control valve 15 and the compressor 11.
When the pressure is lower than the pressure between the flow control valve 15 and the flow control valve 15, the flow rate control valve 15 opens unilaterally, but the direction of the gas flowing through the flow control valve 15 is the direction from the flow control valve 15 to the evaporator 14. Therefore, the liquid back phenomenon does not occur.

FIG. 2 shows a refrigerator according to the second aspect of the present invention. The refrigerator shown in FIG. 1 is different from the refrigerator shown in FIG. Other than that the opening of the flow control valve 15 is adjusted by the signal from the detector 2, it is substantially the same,
The parts corresponding to each other are designated by the same reference numerals and the description thereof will be omitted. In the refrigerator shown in FIG. 2, the evaporator 14 and the flow control valve 1
The pressure detector 2 is provided in the refrigerant flow path portion between the pressure detector 2 and the pressure detector 5.
Then, in addition to the control of the flow rate adjusting valve 15 described above, the refrigerant flow rate value in the flow rate adjusting valve 15 is calculated from the pressure detected by the pressure detector 2 and the pressure detector 19 and the opening degree of the flow rate adjusting valve 15. When the refrigerant flow rate value is smaller than the allowable value, the opening degree of the flow rate control valve 15 is increased immediately after the compressor is started within a range in which the refrigerant flow value does not exceed the allowable value. This makes it possible to increase the opening degree of the flow rate control valve 15 faster without causing the liquid back phenomenon. A temperature detector may be provided instead of the pressure detector 2, and in this case, the pressure in the refrigerant flow path portion can be calculated from the detected temperature, and the opening degree of the flow rate adjusting valve 15 can be calculated in the same manner as above. It can be adjusted.

FIG. 3 shows a refrigerator according to the third aspect of the present invention. The refrigerator shown in FIG. 1 is different from the refrigerator shown in FIG. Is substantially the same except that the opening degree of the expansion valve 13 is adjusted also by a signal from the liquid level gauge 3 that detects the liquid level of the refrigerant liquid in the evaporator 14 provided in The parts corresponding to each other are designated by the same reference numerals and the description thereof is omitted.
In the refrigerator shown in FIG. 3, when the liquid level detected by the liquid level gauge 3 is high, the opening degree of the expansion valve 13 is reduced to accelerate the evaporation of the refrigerant liquid in the evaporator 14 to increase the liquid level. It is formed so as to decrease. As a result, the liquid back phenomenon is further unlikely to occur. In addition, in FIG. 3, * marks indicate that they are continuous. The refrigerator shown in FIG. 3 may be further provided with the pressure detector 2 in the refrigerator shown in FIG. 2 so that the flow rate adjusting valve 15 similar to that of the refrigerator shown in FIG. 2 can be adjusted. Instead of the pressure detector 2, a temperature detector may be provided to perform the same adjustment as above.

[0016]

As is apparent from the above description, according to the first aspect of the present invention, in the refrigerator provided with the closed loop of the refrigerant including at least the compressor, the condenser, the expansion valve, the evaporator and the flow rate control valve, A pressure detector that detects the pressure of the refrigerant suction gas of the compressor, and keeps the flow control valve at the minimum opening within a controllable range before starting the compressor, and after starting the compressor, uses the pressure detector. When the detected pressure is lower than the set value, the flow rate control valve is gradually opened, and in other cases, a control means having a function of holding the opening degree of the flow rate control valve is provided and formed. is there. For this reason, it is possible to reduce the loss of power, prevent the occurrence of the liquid back phenomenon, and prevent the occurrence of the poor lubrication phenomenon when the compressor is an oil cooling type.

According to the second aspect of the invention, a temperature or pressure detector is provided in the refrigerant flow passage portion between the evaporator and the flow rate control valve, and the control means is provided from the temperature or pressure detector. The refrigerant flow rate value in the flow rate control valve is calculated from the pressure of the refrigerant flow path portion obtained based on the signal, the pressure of the suction refrigerant gas, and the opening degree of the flow rate control valve, and this refrigerant flow rate value is an allowable value. If less than
It also has a function of increasing the opening degree of the flow rate control valve immediately after the compressor is started within a range in which the refrigerant flow rate value does not exceed the allowable value. Therefore, in addition to the effects of the first invention,
It is possible to increase the opening degree of the flow rate control valve faster without causing the liquid back phenomenon.

Further, according to the third aspect of the invention, the evaporator is provided with a liquid level gauge for detecting the liquid level of the refrigerant liquid therein, and the control means controls the liquid level detected by the liquid level gauge. When it is high, it also has a function of reducing the opening of the expansion valve. Therefore, in addition to the effects of the first and second aspects of the invention, as a result of lowering the liquid level of the refrigerant liquid in the evaporator, the liquid back phenomenon is further less likely to occur.

[Brief description of drawings]

FIG. 1 is a diagram showing an overall configuration of a refrigerator according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an entire configuration of a refrigerator according to a second embodiment of the present invention.

FIG. 3 is a diagram showing an overall configuration of a refrigerator according to a third aspect of the present invention.

FIG. 4 is a diagram showing an overall configuration of a conventional refrigerator.

[Explanation of symbols]

1 Control means 2 Pressure detector 3 Liquid level gauge 11 Compressor 12 Condenser 13 Expansion valve 14 Evaporator 15 Flow control valve 19 Pressure detector

Continuation of the front page (56) Reference JP-A-4-251161 (JP, A) JP-A-4-28958 (JP, A) JP-A-63-87555 (JP, A) JP-A-6-281300 (JP , A) JP-A-1-256760 (JP, A) JP-A-1-256770 (JP, A) Actual development Sho 59-76955 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB) Name) F25B 1/00 304

Claims (3)

(57) [Claims] 1. A refrigerator provided with a closed loop of a refrigerant including at least a compressor, a condenser, an expansion valve, an evaporator and a flow rate control valve, and a pressure detector for detecting the pressure of a refrigerant gas sucked into the compressor, Before starting the compressor, keep the flow control valve at the minimum opening within the controllable range, and after starting the compressor, if the pressure detected by the pressure detector is lower than the set value, turn the flow control valve on. A refrigerating machine which is gradually opened, and is provided with control means having a function of holding the opening degree of the flow rate control valve in other cases. 2. A temperature or pressure detector is provided in a refrigerant flow path portion between the evaporator and the flow rate control valve, and
Refrigerant flow rate in the flow rate control valve from the pressure of the refrigerant flow path portion, the pressure of the suction refrigerant gas, and the opening degree of the flow rate control valve, which are obtained by the control means based on the signal from the temperature or pressure detector. If the refrigerant flow rate value is smaller than the allowable value, it also has the function of increasing the opening of the flow rate control valve immediately after the compressor is started within the range where the refrigerant flow value does not exceed the allowable value. The refrigerator according to claim 1, wherein 3. The liquid level gauge for detecting the liquid level of the refrigerant liquid inside the evaporator is provided, and the expansion valve is provided when the liquid level detected by the level gauge is high by the control means. The refrigerator according to claim 1 or 2, further comprising a function of reducing the opening of the refrigerator.