JPH09196477A - Compression type refrigerator and method for controlling the operation thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the superheating or frosting, freezing, etc., at the time of low or high load and to conduct the efficient operation in a compression type refrigerator. SOLUTION: A pressure reducing valve 7 for controlling the pressure (temperature) of the outlet of an evaporator 4 is inserted between the evaporator 4 and a compressor 1 to throttle the valve 7 at the time of low or high load, and the pressure and temperature of the evaporator 4 are regulated to prevent the superheating, frosting or freezing. Further, in addition to the valve 7, the opening of the valve 3 and the number of revolutions of a prime mover 1a are independently controlled to control the superheat degree of the evaporator 4 and the temperature of material to be cooled. Accordingly, the efficient operation can be conducted, and energy conservation is attempted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a compression refrigerator capable of preventing frost formation, freezing and operating efficiently, and an operation control method thereof.

[0002]

2. Description of the Related Art As shown in FIG.
The compressor 1 compresses the refrigerant and guides it to the condenser 2, where the refrigerant vapor is condensed and guided to the expansion valve 3, and the expansion valve 3
With the configuration in which the refrigerant is evaporated by the evaporator 4 while controlling the expansion amount of the refrigerant by, cooling or freezing is performed. In the figure, 1a is a prime mover (motor) for driving the compressor 1, 5 is a bypass circuit for bypassing the compressor 1, and 6 is a bypass valve inserted in the bypass circuit 5.

In the case of the above conventional compression refrigerator, the expansion valve 3
By adjusting the pressure at the outlet of the evaporator 4, the degree of superheat of the evaporator 4 is controlled to be constant, and the circulation of the refrigerant is controlled by controlling the rotation speed of the prime mover 1a or starting (stopping or repeating) the prime mover 1a. A control method has been adopted in which the capacity is controlled to cope with load fluctuations.

[0004]

However, the above-mentioned conventional compression refrigerator and this operation control method have the following drawbacks. 1. There is a limit to the number of revolutions that can be used by the prime mover 1a, and the number of revolutions cannot be reduced below a certain value. That is the lower limit of capacity control. On the other hand, when operating at a low load below this lower limit, the expansion valve 3 is throttled by the superheat control of the expansion valve 3,
The pressure and temperature of the evaporator 4 fall below the allowable limit. In this case, for example, frosting of the evaporator 4 occurs in an air conditioner, and cold water freezes in a cold water generator.

[0005] 2. Conventionally, when there is a danger of frost formation or freezing, capacity control is performed by starting and stopping the prime mover 1a, but when this starting and stopping is performed, the generated cold heat greatly fluctuates.

[0006] 3. For the purpose of eliminating the above-mentioned disadvantages of FIG.
There is also a method of reducing the amount of refrigerant flowing to the evaporator 4 while maintaining the rotation speed of the prime mover 1a constant by providing the bypass circuit 5 and controlling the capacity for bypassing the inside of the bypass circuit 5 as described above. In this case, the efficiency is poor, especially for multi-type air conditioners.

[0007] 4. When the prime mover 1a does not have the rotation speed control function, the capacity control is performed by starting and stopping the prime mover 1a, but in the case of this control method, the same problems as described in 2 and 3 above occur.

[0008] 5. When the pressure of the evaporator 4 is too high at the time of startup or high load, the prime mover 1a becomes overloaded.

6. In the compression refrigerator, a. The degree of superheat at the outlet of the evaporator 4 can be controlled to prevent liquid compression of the compressor 1, b. The capacity of the circulating refrigerant can be controlled, and c. It is desirable to be able to control the temperature of the evaporator 4 in a certain state, that is, to prevent frosting and freezing of the object to be cooled around the evaporator 4, and for this reason, conventionally, the opening degree of the expansion valve 3 and the rotation of the prime mover 1a are conventionally. There are only two types of control, that is, a combination of numerical control or a combination of the opening degree of the expansion valve 3 and the bypass valve 6,
They are not individually controlled. Therefore, three control devices are required in order to independently control the above ac.

[0010]

Means for Solving the Problems The present invention provides the above-mentioned 1
The purpose is to solve the problems of (6) to (6), and the configuration is as follows. 1. In the refrigerant circulation system, a pressure reducing valve is inserted between the evaporator and the compressor, and the pressure and temperature of the evaporator are adjusted by squeezing the pressure reducing valve when the load is low or high, and A compression type refrigerator configured to reduce the load on a prime mover for driving the compressor by adjusting the suction pressure.

2. By inserting a pressure reducing valve between the evaporator and the compressor in the refrigerant circulation path passing through the compressor, the condenser, the expansion valve, and the evaporator, and reducing the pressure reducing valve at the time of low load or high load, Adjusting the pressure and temperature of the evaporator, adjusting the suction pressure of the compressor, controlling the expansion valve to control the degree of superheat at the outlet of the evaporator, rotation of the prime mover for driving the compressor A method for controlling the operation of a compression refrigerator, wherein the temperature of the cooled object is adjusted by controlling the number.

[0012]

[Action]

In the case of configuration 1, when the prime mover has a rotation speed control function, this rotation speed control responds to load fluctuations, and when it exceeds the rotation speed control range, the pressure reducing valve is throttled to reduce the suction pressure of the compressor. Is controlled, the circulation amount of the refrigerant flowing through the compressor is reduced to keep the pressure and temperature of the evaporator constant, and the load on the prime mover is reduced. When the prime mover does not have the rotation speed control function, the pressure reducing valve is throttled to cope with a low load or a high load, and the prime mover is not started or stopped.

In the case of configuration 2, the degree of superheat at the outlet of the evaporator is controlled by an expansion valve, the temperature of the object to be cooled is controlled by the rotation speed of the prime mover, and the pressure (temperature) of the evaporator and the suction pressure of the compressor are reduced valves. To control each independently. However,
In principle, each of these controls is performed independently,
Depending on the conditions, more efficient operation can be achieved by controlling them in combination.

[0014]

DETAILED DESCRIPTION OF THE INVENTION Claims 1 and 2 based on FIG.
The embodiments of the described invention will be described in detail. FIG. 1 shows a refrigerant circulation path of a compression refrigerator, 1 is a compressor, 1a is a prime mover with a rotation speed control function, 2 is a condenser, 3 is an expansion valve, 4 is an evaporator,
Reference numeral 7 is a pressure reducing valve.

In the case of the above-described embodiment, a normal load fluctuation is dealt with by controlling the rotation speed of the prime mover 1a, and at the time of a low load or a high load exceeding the rotation speed control range, the pressure reducing valve 7 is throttled to reduce the evaporator 4a. Controls the pressure (temperature) to prevent problems such as frost and freezing. Further, the degree of superheat at the outlet of the evaporator 4 is controlled by the opening degree of the expansion valve 3, and the amount of the circulating refrigerant is controlled by controlling the rotation speed of the prime mover 1a to control the temperature of the object to be cooled.

The above embodiment is a case of a prime mover with a rotation speed control function. However, in the case of a prime mover with a constant rotation speed, the pressure (temperature) of the evaporator 4 is controlled by the pressure reducing valve 7 to expand the expansion valve. The superheat degree at the outlet of the evaporator 4 is controlled by 3. Although the controls in the above-described embodiments are examples of independent control, it is also possible to control these controls in combination. Each control detects a load, and the controller performs it based on this load.

[0016]

As described above, according to the present invention, the pressure (temperature) of the evaporator is controlled by inserting the pressure reducing valve between the evaporator and the compressor and squeezing the pressure reducing valve at the time of low load or high load. As a result, frost formation, freezing or overheating can be prevented.
In addition, the pressure reducing valve, the expansion valve, and the rotational speed of the prime mover are independently controlled to control the evaporator pressure (temperature), the evaporator outlet superheat degree, and the temperature of the cooled object. You can Therefore, in the compression type refrigerator, energy can be saved by efficient operation, and the operation control device can be simplified.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an example in which the present invention is applied to a compression refrigerator.

FIG. 2 is an explanatory diagram of a conventional compression refrigerator.

[Explanation of symbols]

 1 Compressor 1a Motor with rotation speed control function 2 Condenser 3 Expansion valve 4 Evaporator 7 Pressure reducing valve

Claims (2)

[Claims] 1. A pressure reducing valve is inserted between an evaporator and a compressor in a refrigerant circulation path, and the pressure reducing valve is throttled at the time of low load or high load to adjust the pressure and temperature of the evaporator. A compression refrigerator that is configured to reduce a load on a driving motor of the compressor by adjusting a suction pressure of the compressor. 2. A pressure reducing valve is inserted between the evaporator and the compressor in a refrigerant circulation system passing through the compressor, the condenser, the expansion valve, and the evaporator, and the pressure reducing valve is operated under low load or high load. Adjusting the pressure and temperature of the evaporator by squeezing, adjusting the suction pressure of the compressor, adjusting the superheat degree of the evaporator outlet by controlling the expansion valve, A method for controlling the operation of a compression refrigerator, wherein the temperature of an object to be cooled is adjusted by controlling the rotation speed of a driving prime mover.