JPH07117301B2 - Refrigeration system operation controller - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an operation control device for a refrigerating device provided in a refrigerating container or the like, and particularly to a measure for controlling an upper limit value of an opening of an expansion valve.

(Prior Art) Conventionally, as an operation control device for this type of refrigeration system,
For example, there is one disclosed in Japanese Utility Model Laid-Open No. 63-46360.

That is, a hot gas bypass line that bypasses the condenser and the expansion valve while configuring a refrigerant circulation circuit by sequentially connecting a compressor with an adjustable capacity, a condenser, an expansion valve with an adjustable opening degree, and an evaporator When the heat load fluctuates and the temperature inside the storage chamber becomes higher than a predetermined temperature range set with a predetermined width with respect to a desired temperature inside the storage chamber, the capacity of the compressor is increased and the opening degree of the expansion valve is increased. Is controlled so that the internal temperature falls within a predetermined temperature range. When the temperature inside the refrigerator is within the predetermined temperature range, the amount of hot gas flowing through the hot gas bypass line is controlled so that the temperature inside the refrigerator converges to the set temperature inside the refrigerator.

In the operation control device of this refrigeration system, conventionally, when it is attempted to reduce the capacity of the compressor from the steady operation state, the refrigerant liquid amount flowing through the liquid line of the refrigerant circulation circuit and the hot gas amount flowing through the hot gas bypass line are simultaneously obtained. There is a problem that it must be detected, and control becomes difficult.

Therefore, there is one in which an electronic expansion valve is used to control the refrigerant circulation amount of the refrigerant circulation circuit so that the internal cold storage temperature becomes a predetermined temperature. This electronic expansion valve is controlled by the deviation of the inlet / outlet temperature of the refrigerant in the evaporator, while the electronic expansion valve is set to an upper limit value of opening (for example, 50%) to prevent overload of the compressor during pull-down at the initial stage of operation. In addition to preventing, high pressure cut is also prevented.

(Problems to be Solved by the Invention) However, in this configuration, the opening upper limit value of the electronic expansion valve is set corresponding to the pull-down time, and is configured to uniformly act regardless of the capacity of the compressor. ing.

Therefore, when the compressor is operating under reduced load due to low internal heat load capacity, etc., it is suitable for the maximum load of the compressor even though there is little risk of overload operation or high pressure cut of the compressor. The upper limit of the opening degree of the electronic expansion valve is set, and the following inconvenience occurs.

That is, the evaporator, which is the internal heat exchanger, should keep the temperature as high as possible within the range necessary for maintaining the internal temperature in order to prevent moisture from frosting due to the transfer from the internal articles. I have to.

However, for example, as shown in FIG. 5, the capacity is 67%.
When the compressor is operating at, if the opening upper limit value of the electronic expansion valve is not set, the required refrigerating capacity can be secured at point B, but the opening upper limit value is set as described above. Therefore, it was necessary to increase the capacity of the compressor to 100% and secure the refrigeration capacity at point A. Therefore, since the compressor is operated at a high capacity, there is a problem that the temperature of the refrigerant in the evaporator is lowered and the amount of frost is increased although it is desired to be reduced. Further, there is a problem that the humidity in the refrigerator is lowered, the articles in the refrigerator are adversely affected, and energy saving cannot be achieved.

The present invention has been made in view of these points, and by increasing the opening upper limit of the expansion valve in accordance with the decrease in the capacity of the compressor, it is possible to maintain the refrigerant temperature in the evaporator at an optimum value. The purpose is to do.

(Means for Solving the Problems) In order to solve the above problems, the means taken by the present invention is, as shown in FIG. 1, first, a compressor (1) and a condenser (3) with adjustable capacities. ), Expansion valve with adjustable opening (5)
And a refrigerant circulation circuit (8) in which the evaporator (6) is connected in a closed circuit, and a capacity control means (14) for controlling the capacity of the compressor (1) according to the heat load in the refrigerator. ing.

Then, the opening degree of the expansion valve (5) is controlled so that the degree of superheat of the refrigerant in the evaporator (6) reaches a predetermined value during the refrigerating operation, and the outlet air temperature becomes a predetermined temperature during the refrigerating operation. An expansion valve control means (12) for controlling is provided.

Further, when the opening degree of the expansion valve (5) reaches a preset upper limit value, an upper limit value control means (15) for controlling the expansion valve control means (12) so as to prevent the expansion valve (5) from opening. ) Is provided.

In addition, upon receiving the capacity signal from the capacity control means (14) of the compressor (1), the expansion valve of the upper limit value control means (15) decreases as the capacity of the compressor (1) decreases during refrigeration operation. An upper limit value changing means (1) for changing the upper limit value of the upper limit value regulating means (15) so that the opening upper limit value of (5) becomes large.
6) is provided.

Next, the means taken by the invention according to claim (2) is, in the operation control device of the refrigerating apparatus according to claim (1), the compressor (1) is configured to have a variable capacity in a plurality of stages, while the upper limit is set. The value changing means (16) is configured to change the opening upper limit value of the expansion valve (5) into a plurality of types according to the number of capacity stages of the compressor (1).

(Operation) With the above configuration, when the compressor (1) is driven, the refrigerant circulates in the refrigerant circulation circuit (8) while the expansion valve control means (1
2) controls the opening degree of the expansion valve (5) so that the degree of superheat of the refrigerant in the evaporator (6) reaches a predetermined value during the refrigerating operation, and the outlet air temperature reaches a predetermined temperature during the refrigerating operation. The opening degree of the expansion valve (5) is controlled, and the capacity control means (14) controls the compressor capacity in accordance with the internal heat load capacity to maintain an appropriate internal temperature.

Now, when the capacity of the compressor (1) changes, specifically,
In the invention according to claim (2), when it changes stepwise, the upper limit value changing means (16) receiving the capacity signal from the capacity control means (14) of the compressor (1) opens as the compression capacity decreases. Increase the upper limit value.

By the control, the upper limit control means (15) controls the expansion valve control means (12) so that the opening degree of the expansion valve (5) during the freezing operation and the refrigerating operation does not exceed the upper limit value corresponding to the compression capacity.
To control.

Therefore, the amount of the refrigerant according to the operation mode is supplied to the evaporator (6), so that the temperature of the refrigerant can be kept high and frost formation can be prevented.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

As shown in FIG. 2, (A) is a refrigerating device provided in a refrigerating container or the like, (1) is a compressor with an unloader capable of changing the capacity to 33%, 67% and 100% in three stages, ( 3) is a condenser equipped with an air cooling fan (F1) and a motor (MF1),
(4) is the receiver, (5) is PI depending on the physical state of the refrigerant
An electronic expansion valve controlled by D, (6) is an evaporator equipped with an internal fan (F2) and a motor (MF2), and (7) is an accumulator.

And each device (1,3,4,5,6,7) is connected in series by the refrigerant pipe in the above-mentioned order to form a refrigerant circulation circuit (8), and the refrigerant is compressed by the compressor (1). By circulating and circulating the refrigerant circulation circuit (8), the heat of the refrigerant gas is released to the outside of the refrigerator in the condenser (3) to liquefy the refrigerant gas, and the refrigerant gas is vaporized in the evaporator (6). By doing so, the heat inside the refrigerator is absorbed, and the inside of the refrigerator is thereby cooled.

Further, (2) is a three-way proportional valve provided between the compressor (1) and the condenser (3), and (9) has one end connected to the three-way proportional valve (2) and the other. A hot gas bypass line whose end bypasses the condenser (3), the receiver (4) and the electronic expansion valve (5) and is connected to the suction side refrigerant pipe (10) of the evaporator (6). The gas bypass line (9) includes a drain pan heater section (11).

Also, (HPS) is a pressure sensor for high pressure, (Th1) and (Th
2) is a refrigerant temperature sensor for detecting the inlet refrigerant temperature and the outlet refrigerant temperature of the evaporator (6), and (Th3) and (Th4) are the suction air temperature and the blown air temperature (inside the refrigerator) of the evaporator (6). It is an air temperature sensor that detects temperature).

The detection signals of the temperature sensors (Th1, Th2, Th3, Th4) are configured to be input to the controller (21), and the controller (21) is configured to operate as shown in FIG. A / D converter (33), I / O port (24), RAM (2
5), ROM (26) and CPU (27).

Further, in the controller (21), when the motor (MEV) of the electronic expansion valve (5) is in the refrigerating operation, the refrigerant temperature difference between the inlet and outlet of the evaporator (6) is detected by the detection signals of the refrigerant temperature sensors (Th1, Th2). PID control based on the degree of superheat) to control the opening, and PID control so that the blown air temperature reaches the set value by the detection signal of the air temperature sensor (Th4) on the blow side of the evaporator (6) during refrigeration operation. Expansion valve control means (12) for controlling the opening degree and three-way proportional valve (2) during defrost operation
Hot gas control means (13) for controlling the motor (MV) of the compressor and adjusting the amount of hot gas flowing through the hot gas bypass line (9), and capacity control means (14) for controlling the capacity of the compressor (1). Is provided.

Further, in the controller (21), the expansion valve control means (12) is arranged so as to prevent the electronic expansion valve (5) from opening when the opening degree of the electronic expansion valve (5) reaches a preset upper limit value. ) Controlling the upper limit value (15) and the capacity control means (14) of the compressor (1) to receive a capacity signal,
As the capacity of the compressor (1) during refrigerating operation decreases, the electronic expansion valve (5) of the upper limit value regulating means (15)
So that the opening upper limit value of the
An upper limit value changing means (16) for changing the upper limit value of 5) is included.

Then, specifically, when the capacity of the compressor (1) is 100%, the upper limit value changing means (16) sets the opening upper limit value of the electronic expansion valve (5) to 50%, and also the compressor (1). If the capacity is 67%, 80%, and if the compressor (1) capacity is 33%,
The upper limit regulating means (15) is controlled so as to be 100%.

Furthermore, in FIG. 3, (Tr) is a transformer, (S) is a start / stop switch, (31) is a high pressure switch, (32)
Is a low pressure switch, (33) is a hydraulic protective pressure switch, (3
4) is a lamp switch, (35) is a hydraulic reset switch, (36) is a compressor protection thermoswitch, (37) is for switching the transformer (Tr) wiring, (38) is for voltage switching, and (39,4)
Reference numeral 0) is a manual switching switch for the compressor motor, and the switches (37-40) are all interlocked.

(MC) is a compressor motor, and (10c) is a normally open contact (10C-1) that allows energization of the blower fan motor (MF1) of the condenser (3) while operating the compressor motor (MC). ) Has a compressor relay, (10F) is an evaporator fan relay having a normally open contact (10F-1) for operating the blower fan motor (MF2) of the evaporator (5), and (20S-1) is a refrigerant pipe. It is a solenoid valve relay that allows or blocks the flow of refrigerant.

Next, based on the flow of FIG. 4, a procedure for setting the set value of the upper limit of the opening degree of the electronic expansion valve (5) according to the reduction of the compression capacity of the compressor (1) in the above embodiment will be described.

During the refrigerating operation, first, in step ST1, the capacity of the compressor (1) is detected, and then in step ST2, it is judged whether or not the capacity of the compressor (1) is 100%.
If it is%, the process proceeds to step ST3, the upper limit of the opening degree of the electronic expansion valve (5) is set to 50%, and then the process returns to step ST1 and the same operation is repeated. Then, in step ST2, if the capacity of the compressor (1) is not 100%, the process proceeds to step ST4, and it is determined whether or not the capacity of the compressor (1) is 67%. If it is 67%, the process proceeds to step ST5, the upper limit of the opening degree of the electronic expansion valve (5) is set to 80%, and then the process returns to step ST1 and the same operation is repeated.

Further, in step ST4, the capacity of the compressor (1) is 67
If not, move to step ST6, set the upper limit of opening degree of the electronic expansion valve (5) to 100%, and then execute step ST1.
Return to and the same operation is repeated.

Therefore, during the refrigerating operation, as shown in FIG. 5, the compressor (1) is conventionally operated at the point A, whereas the compressor (1) can be operated at the point B having a low capacity. Therefore, it is possible to prevent frost formation on the evaporator (1), prevent dehumidification of the inside of the refrigerator, and save energy.

Although the hot gas bypass line (9) is provided in this embodiment, it is not necessarily provided in the present invention.

Further, the compressor (1) is not limited to the three types of capacity stages, and may be one that can be changed to a stopped state of 100% and 50%, or one that can be continuously changed.

Further, the opening upper limit value of the expansion valve (5) is not limited to three types in response to the change in the capacity of the compressor (1), and may be two types or continuously changing.

(Effect of the invention) As described above, in the present invention, the upper limit of the opening degree of the expansion valve is set in accordance with the compression capacity of the compressor during the refrigerating operation, so that there is a risk of overload operation and high pressure cut of the compressor. Without
Since the required amount of refrigerant for the evaporator can be supplied, the temperature of the evaporator can be maintained high within the range necessary for maintaining the internal temperature of the refrigerator, and frost formation can be prevented. Therefore, uneven flow, non-uniform temperature distribution in the warehouse due to non-uniform temperature of air blown in the warehouse, loss and deterioration due to dehumidification of articles in the warehouse can be reduced, and energy saving can be achieved by the capacity reduction operation of the compressor. it can.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention, FIG. 2 is a system diagram of an embodiment of the present invention, FIG. 3 is a connection diagram of the embodiment, FIG. 4 is a flow chart of the embodiment, and FIG. It is a characteristic view of the refrigerating capacity and the expansion valve opening in each compressor capacity. (1) ... compressor, (3) ... condenser, (5) ... electronic expansion valve, (6) ... evaporator, (8) ... refrigerant circulation circuit,
(12) …… Expansion valve control means, (14) …… Capacity control means,
(15) …… Upper limit regulation means, (16) …… Upper limit change means.

Claims (2)

[Claims] 1. A refrigerant circulation circuit in which a compressor (1) with adjustable capacity, a condenser (3), an expansion valve (5) with adjustable opening and an evaporator (6) are connected in a closed circuit. (8), the capacity control means (14) for controlling the capacity of the compressor (1) according to the heat load in the refrigerator, and the opening degree of the expansion valve (5) such that the evaporator (6) during the refrigerating operation.
The expansion valve control means (12) for controlling the superheat degree of the refrigerant in (1) to a predetermined value and controlling the blown air temperature to a predetermined temperature during refrigeration operation, and the opening degree of the expansion valve (5) are An upper limit value control means (15) for controlling the expansion valve control means (12) so as to prevent the expansion valve (5) from opening when a preset upper limit value is reached, and a capacity control of the compressor (1). In response to the capacity signal from the means (14), the opening upper limit value of the expansion valve (5) of the upper limit value regulating means (15) increases as the capacity of the compressor (1) during refrigeration operation decreases. And an upper limit changing means (16) for changing the upper limit of the upper limit regulating means (15). 2. The operation control device for a refrigeration system according to claim 1, wherein the compressor (1) is configured to have a variable capacity in a plurality of stages, and the upper limit value changing means (16) is the compressor (1). ) The operation control device for a refrigeration system, which is configured to change the upper limit value of the opening degree of the expansion valve (5) to a plurality of types according to the number of capacity stages.