JPH06323638A - Control system for refrigerator - Google Patents

Abstract

(57) [Summary] [Composition] A refrigeration cycle is composed of a compressor 1, a condenser 2, an electronic expansion valve 3, an evaporator 4 and a refrigerant pipe connecting these, which are controlled by an operating frequency. It is controlled by the controller 5 based on the information. The controller 5 is prepared for controlling the opening degree of the electronic expansion valve 3 for each fluid set temperature or for each of several set temperature regions. When the fluid set temperature is input, the electronic expansion valve 3 The valve opening control is determined, and thereafter, the operation is performed by the valve opening control. [Effect] The responsiveness of the refrigerating capacity is good, and the heat exchanging capacity of the evaporator is the capacity that matches the fluid set temperature, so the stability of the refrigerating cycle is good.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to temperature control of a fluid cooled by a refrigerating apparatus, and more particularly to expansion of a temperature range for installing the fluid, highly accurate temperature control, and stable continuous operation.

[0002]

2. Description of the Related Art As a conventional technique, Japanese Patent Application Laid-Open No. 2-4165 discloses that an inverter drives an operating frequency of a compressor in a refrigeration cycle in order to cool the cold water returned to a refrigeration system by absorbing a heat load of a heating element. Is described to control the capacity of the refrigerating capacity to supply cold water at a stable temperature at all times.

[0003]

In the conventional refrigeration system,
The refrigeration cycle does not liquid-compress the refrigerant in the compressor, that is,
The expansion valve is controlled so that the refrigerant completely becomes a gas at the evaporator outlet and sends the appropriately heated refrigerant to the compressor. However, when the expansion valve is controlled only by the control conditions (set a moderate degree of superheat), the expansion valve does not have a predetermined opening, so the valve opening adjustment is repeated near the set value, and the electronic expansion valve Has a shorter life. Further, since the electronic expansion valve repeats the valve opening adjustment, the response of the refrigerating capacity adjustment is slow and the refrigerating capacity varies. Therefore, by adjusting the valve opening degree of the electronic expansion valve to the operating frequency of the compressor so that the degree of superheat is appropriate, if the electronic expansion valve is controlled in advance, the frequency at which the valve moves in the electronic expansion valve will be less than the above control. Lifespan is extended. Further, since the frequency of movement of the electronic expansion valve decreases, the refrigerating capacity has a good response and the temperature of the fluid to be cooled is stable. However, when expanding the cooling set temperature range of the fluid by this control method, the temperature difference between the refrigerant and the fluid in the evaporator is different between the upper limit region and the lower limit region of the cooling set temperature. , In the cooling set temperature upper limit region, the heat exchanger capacity is small and the superheat degree is large, and the refrigeration cycle is in an overload operation state.On the other hand, in the cooling set temperature lower limit region, the heat exchanger capacity is too large, so the superheat degree It becomes smaller, and the refrigerant does not evaporate sufficiently, which may cause liquid compression.

An object of the present invention is to provide a stable operation of a refrigeration cycle and a stable operation even if a fluid cooling set temperature range is expanded by controlling an electronic expansion valve.

[0005]

A refrigeration system control system according to the present invention is a refrigeration cycle including a compressor, a condenser, and an evaporator whose capacity is controlled by an operating frequency, and uses an electronic expansion valve.
The operating frequency of the compressor and the valve opening degree of the electronic expansion valve are controlled by the means for detecting the temperature of the fluid cooled by the evaporator and the control means for calculating the information, and the operating frequency of the compressor is controlled. On the other hand, in a refrigeration system of a type that controls the opening degree of the electronic expansion valve by a predetermined valve opening degree, setting of a fluid that cools the valve opening degree of the electronic expansion valve that changes according to the operating frequency of the compressor. It is characterized in that the valve opening degree of the electronic expansion valve is controlled according to the operating frequency of the compressor by setting and storing in the control means for each temperature.

[0006]

The valve opening of the electronic expansion valve with respect to the operating frequency of the compressor is determined from the set cooling temperature of the fluid input before the operation of the refrigeration system. After the compressor is started, the electronic expansion valve is adjusted to the operating frequency of the compressor. By controlling the valve opening of, the heat exchanger capacity is adjusted even if the fluid temperature is in the upper and lower limits, so there is an appropriate degree of superheat at the compressor inlet, stable refrigeration cycle operation, and fluid temperature Control can be performed.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a system diagram of the refrigerating apparatus according to this embodiment. A refrigeration cycle is configured by a compressor (for example, a compressor driven by a variable frequency inverter) capable of controlling the capacity, a condenser 2, an electronic expansion valve 3, an evaporator 4, and a refrigerant pipe connecting these components, A controller 5 and a fluid temperature sensor 6 are attached to this. The condenser 2 is adapted to exchange heat with cooling water or the outside air (FIG. 1 is an air-cooled type), while the evaporator 4 is adapted to exchange heat with the fluid flowing from the pipes 7 to 8. And this fluid is used to cool other objects to be cooled. Although the fluid temperature sensor 6 is installed in the pipe 8, it may be installed in the pipe 7.
In the refrigeration system, the fluid temperature sensor 6 detects the temperature of the fluid, and the controller 5 controls the capacity of the compressor 1 based on the detected temperature, and the valve opening degree of the electronic expansion valve 3 corresponds to the capacity control of the compressor 1. The valve opening is controlled to maintain the fluid temperature at a desired temperature.

In the refrigerating apparatus, the following control is performed in this embodiment so that the fluid temperature control can be performed with high accuracy and the ball operation can be stably performed even if the fluid temperature setting range is expanded.

The fluid cooling temperature is set before the operation of the refrigerating apparatus. When this set temperature is input to the controller 5, the controller 5 sets each preset temperature (for example, 1 ° C. unit).
The valve opening control of the electronic expansion valve 3 is selected from the input set temperatures. Alternatively, as shown in FIG. 2, the fluid cooling set temperature is divided into a high temperature range 11, a standard range 12, and a low temperature range 13, and an electronic expansion valve opening control line corresponding to the set temperature input to the controller 5 is selected. Good. Since the valve opening degree of these electronic expansion valves 3 prepared in advance is set to the heat exchanger capacity matched to the fluid cooling set temperature in the evaporator 4, the refrigerant at the outlet of the evaporator 4 has an appropriate degree of superheat and is compressed. The load on the machine 1 is not burdened, and the valve opening control of the electronic expansion valve 3 immediately responds to the capacity control of the compressor 1. Therefore, the responsiveness of the refrigeration capacity is fast and the temperature control of the fluid is also quick. Converges to the set temperature. By such refrigeration cycle control, the refrigeration system can perform highly accurate temperature control and stable operation even if the fluid temperature setting range is expanded.

[0010]

According to the present invention, since the electronic expansion valve is immediately controlled to a predetermined valve opening for the capacity control of the compressor,
The response of the refrigerating capacity is good, and the accuracy of fluid temperature control can be improved.

Further, since the valve opening degree of the electronic expansion valve is set for each set temperature of the fluid to be cooled or for each set temperature region, even if the set temperature range of the fluid is expanded, evaporation is performed in accordance with the set temperature. The heat exchanger capacity of the compressor is adjusted, the refrigerant can maintain an appropriate degree of superheat at the evaporator outlet, and stable refrigeration cycle operation can be performed without burdening the compressor, and the set temperature range of the fluid can be expanded. Can achieve highly accurate temperature control.

Furthermore, the present invention is economical because it is only necessary to change the control (for example, change the microcomputer software) without adding auxiliary equipment to the refrigeration cycle.

[Brief description of drawings]

FIG. 1 is a system diagram of a refrigerating apparatus to which the present invention is applied.

FIG. 2 is an explanatory diagram of a valve opening degree of an electronic expansion valve to which the present invention is applied.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Compressor whose capacity can be controlled, 2 ... Condenser, 3 ... Electronic expansion valve, 4 ... Evaporator, 5 ... Controller, 6 ... Fluid temperature sensor,
7, 8 ... Piping.

Claims (1)

[Claims] 1. A compressor whose capacity is controlled by an operating frequency,
In a refrigeration cycle including a condenser and an evaporator, using an electronic expansion valve, a means for detecting the temperature of a fluid cooled in the evaporator and a control means for computing the information, the operating frequency of the compressor, the electronic Control the valve opening of the expansion valve, with respect to the operating frequency of the compressor, in the refrigeration system of the method of controlling the opening of the electronic expansion valve by a predetermined valve opening, the operating frequency of the compressor The valve opening of the electronic expansion valve is controlled in accordance with the operating frequency of the compressor by setting and changing the valve opening of the electronic expansion valve for each set temperature of the fluid to be cooled. A refrigeration system control method characterized by the above.