JPS59191854A - Method of controlling refrigeration cycle - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a method of controlling a refrigeration cycle using an electric expansion valve, and in particular, a method of controlling a refrigeration cycle using an electric expansion valve, in particular, giving a constant valve opening to the electric expansion valve whenever a compressor is started. The present invention relates to a method for controlling a refrigeration cycle.

[Technical Background of the Invention] Recently, refrigeration cycle devices are capable of controlling the refrigeration cycle using various signal media.
A refrigeration cycle using an electric expansion valve has been developed.

This is made up of an electric expansion valve placed between the capacitor and the evaporator. Normally, the electric expansion valve is controlled. The opening degree is controlled by changing the opening degree (difference between the temperature of

By the way, when controlling the amount of superheat with an electric expansion valve, at the time of cold start (when the refrigeration cycle starts operating)
The problem is how to control this. That is, at the start of the refrigeration cycle operation, since there is no temperature difference on the evaporator side, it may take several tens of minutes for the cycle temperature to reach the set superheat amount if the above control is relied only on. For this reason, in the past, a control method was adopted in which the electric expansion valve was always kept at a constant valve opening when the compressor was started, to prevent the rise time of the cycle temperature from becoming prolonged at the start of operation. This conventional control method is shown in FIG. 1, which shows the control to change the valve opening of the electric expansion valve in response to changes in the room temperature T during cooling operation. In the figure, the section where the room temperature T is indicated by a solid line corresponds to when the compressor is turned on, and the thermostat, which operates based on the room temperature set temperature TS, is turned off and then turned on again.
The section shown by the dotted line up to N corresponds to the OFF of the compressor. Therefore, when the compressor is started, there is a point a where the operation switch of the refrigeration cycle is turned on, and a point b and point 0 where the thermostat is turned on during the operation of the refrigeration cycle. The valve opening degrees of the electric expansion valve at these points a to 0 are set to a constant value in the fully open direction as initial control.

[Problems with the Background Art] However, although the air conditioner load fluctuation during operation with the thermostat set to 0N10FFI is generally very small, if a constant opening is given to the electric expansion valve each time the compressor is started, it is difficult to maintain consistency with the load. may deviate significantly, and it takes time to obtain the valve opening that corresponds to the load conditions. In other words, the rise of the temperature cycle at startup is delayed, resulting in capacity loss and annual energy consumption efficiency (SE).
This caused a decrease in ER).

[Object of the Invention] The present invention has been made in view of the above circumstances, and its purpose is to improve the rise of the temperature cycle at the time of starting the compressor after the start of operation, and to reduce capacity loss during controlled operation. The object of the present invention is to provide a refrigeration cycle control method that can reduce energy consumption and improve annual energy consumption efficiency.

[Summary of the Invention The above object is achieved according to the present invention as follows. That is, a refrigeration cycle is formed by disposing an electric expansion valve between the condenser and the evaporator (and at the same time, when the compressor is started, a predetermined valve opening is given to the electric expansion valve, and the electric expansion valve is set at the predetermined valve opening. When changing the valve opening of the electric expansion valve based on the temperature difference on the evaporator side, the valve opening of the electric expansion valve given at the time of starting the compressor is changed to This is intended to achieve refrigeration cycle operation without capacity loss by making the start-up of the compressor different from the start-up of the compressor, which is repeated at 0N10FF of the thermostat during refrigeration cycle operation.

Embodiment J of the Invention A preferred embodiment of the refrigeration cycle control method according to the present invention will be described below with reference to the accompanying drawings.

FIG. 2 shows an embodiment of a refrigeration cycle apparatus for carrying out the method of the present invention, in which 1 is a variable capacity compressor, 2 is a condenser, and 3 is an evaporator. Each of these devices is sequentially connected through a refrigerant circulation path 4. Further, an electric expansion valve 5 is provided between the condenser 2 and the evaporator 3, and constitutes a refrigeration cycle 6. On the other hand, 7 in the figure indicates a control unit composed of a microcomputer,
The output side of this control section 7 is connected to the electric expansion valve 5. In addition, the input side of the control section 7 is connected to a temperature sensor 8 provided on the evaporator 3 and a temperature sensor 9 provided on the suction side of the compressor 1, respectively. The desired amount of superheat can be obtained by controlling the opening degree of the electric expansion valve 5 to be successively changed to the set value of the desired amount of superheat through the section 7. In other words, control is performed using super heat. In addition, the other input side of the control unit 7 is connected to a thermostat 20 that turns on and starts the compressor 1 when the indoor temperature exceeds the allowable range of the set temperature.
When the thermostat 20 is turned on, the control unit 7 maintains the opening of the electric expansion valve 5 at the same valve opening as before the compression 11 was stopped, so as to obtain a super-torque amount that can be used when the compressor 1 is restarted. It has become.

The control unit 7 has an initial control setting that always provides a constant valve opening degree to the electric expansion valve 5 at the start of the refrigeration cycle operation, and a control setting for the electric expansion valve 5 while the compressor 1 is operating after the start of the refrigeration cycle operation. A control setting is made to control the opening degree changing operation of No. 5 while keeping the cycle stable. The latter control setting is such that after changing the opening degree, the opening degree is maintained for a certain period of time (usually 30 seconds to 90 seconds) until the refrigeration cycle stabilizes, and then, for example, the suction side temperature of the compressor 1 is changed by 2 degrees. Measure the leakage of the evaporator 3 to determine whether the cycle has stabilized or not. After the cycle has stabilized, calculate the difference between the superheat amount at that time and the set superheat amount. The operation of changing the opening degree of the electric expansion valve 5 is controlled by determining whether or not it is necessary to change the opening degree again. Note that the determination of cycle stability is repeated until the cycle becomes stable. Furthermore, the maintenance of the valve opening degree of the electric expansion valve 5 at the time of starting the compression ta1 by turning on the thermostat 20 is incorporated into the latter control setting.

Here, the electrically operated expansion valve 5 is explained, for example, as shown in FIG.
A valve body 12 is provided in which the valve body 12 communicates with the valve port 11 through the valve port 11, and a valve stem 14 supported by a diaphragm 13 so as to be openable and closable with respect to the valve port 11 is installed inside the valve body 12. A driver 150 screwed into the head so that the ball 15b1 can move forward and backward, and a stepping motor 15 that moves the valve stem 14 forward and backward are installed in this order, and a signal is output from the control section 7. The stepping rotation of the output shaft 15a of the stepping motor 15 moves the driver 150 and the ball 15b forward and backward, so that the valve port 11 can be opened or closed to a required flow area through the diaphragm 13 and the valve stem 14. It has become.

Next, the operation of the refrigeration cycle device configured as described above will be explained.

First, turn the operation switch ONL to operate the compressor 1. As a result, a refrigeration cycle is formed in which the refrigerant circulates through the condenser 2, the electric expansion valve 5, and the evaporator 3. and,
This cycle is performed based on the amount of superheat set in the control section 7, while satisfying various load conditions by changing the opening degree of the electric expansion valve 5, which starts from a constant opening degree under initial control. The operating status of this electrically operated expansion valve 5 is represented by diagrams and flowcharts showing the response status shown in FIGS. 4 and 5.

That is, after a certain opening degree is given to the electric expansion valve 5 and the valve opening degree is maintained for a certain period of time, the set superheat 1-s)-10 and the current evaporator 3 and compressor The control unit 7 outputs an opening change signal ΔX to the electric expansion valve 5 in accordance with the difference ΔS H between the suction side temperature and the superheat amount obtained by the temperature difference from the suction side temperature. As a result, the stepping motor 15 rotates in a stepping manner to change the opening degree.

In this case, the opening degree is maintained for a certain period of 30 to 90 seconds after changing the opening degree, and then superheating ff1sH1 is performed twice by measuring the temperature twice after a time interval.
By measuring SH2, it is determined whether the leakage is stable or not. Then, the control unit 7 controls the super heat amount SH.
, and the superheat amount SH2 are compared and stabilized (SH
, = SH2), the controller 7 then controls the amount of superheat at that time, for example, superheat ff1.
The difference Δ between sH and the set superheat amount SHo
After calculating SH and determining whether or not it is necessary to change the opening degree again, the electric expansion valve 5 is controlled. In this way, the electric expansion valve 5 is always controlled in a stable cycle state that avoids changing operations in the fluctuation range, and this control is performed every time the compressor 1 is restarted and operated. Conventionally, when restarting the compressor 1, the same valve opening as the initial control was given to the electric expansion valve 5 regardless of the load, so the Originally 1
1. Although the value of the required opening change signal Δ× is extremely small, an excessive opening change exceeding this value is forced;
The startup time was slow, resulting in control loss and lower annual energy consumption efficiency.

However, in the present invention, the thermostat 20 is turned on.
When restarting the compressor 1, the same valve opening degree as before the compressor 1 was stopped is given to the electric expansion valve 5.

As shown in FIG. 4, while the compressor 1 is stopped, the valve opening degree of the electric expansion valve 5 is increased, but this is done to speed up the gas balance, and is not a problem in the present invention. is not directly related.

In this way, by maintaining the electric expansion valve 5 at the same valve opening as before the compressor 1 was stopped at the time of restart, the valve opening of the electric expansion valve 5 becomes equal to the load immediately after the compressor 1 is restarted. As a result, the start-up of the air conditioner's refrigeration cycle is quick and the start-up capacity loss can be significantly reduced. As a result, large fluctuations in superheat are avoided throughout the entire period of refrigeration cycle operation, making it possible to obtain stable refrigeration cycle operation, achieving operation without capacity loss, and greatly improving annual energy consumption efficiency. Zuru.

In addition, the reliability of compression 1!11 is also improved because temporary excessive superheat and liquid bags are eliminated.

In the above embodiment, the valve opening degree of the electric expansion valve 5 when the compressor 1 is restarted is maintained at the same opening degree as before the compressor 1 is stopped. Of course, if there is a large variation in the amount of super and -t due to the rise in room temperature during the operation, the same effect can be obtained even if the valve opening degree is increased from before the stop.

[Effects of the Invention] In short, the present invention exhibits the following excellent effects.

(1) Control the valve opening of the electric expansion valve by setting the thermostat to 0N10 at the start of refrigeration cycle operation and during refrigeration cycle operation.
By making the restarts different from the ones repeated by the FF, capacity loss during controlled operation can be significantly reduced, and annual energy consumption efficiency can be improved.

(2) Capacity loss during reorbiting of the compressor can be reduced, so
Temporary excessive super heat and liquid back up can be prevented.
Improves compressor reliability.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the response status of an electric expansion valve in a conventional refrigeration cycle, FIG. 2 is a configuration diagram showing a preferred embodiment of a refrigeration cycle device for carrying out the method of the present invention, and FIG.
Figure 4 shows a cross-sectional view of the electric expansion valve, Figure 4 is a line diagram showing the response status of the electric expansion valve in the refrigeration cycle according to the method of the present invention, and Figure 5 shows the control of the electric expansion valve. It is a flowchart diagram showing the transition. In the figure, 1 is a compressor, 2 is a condenser, 3 is an evaporator, 5 is an electric expansion valve, and 7 is a control section. Representative Patent Attorney Noriyuki Chika (1 other person) Tsuyoshi Tsuyoshi

Claims (2)

[Claims] (1) An electric expansion valve is arranged between the condenser and the evaporator to form a refrigeration cycle, and a predetermined valve opening is given to the electric expansion valve when the compressor is started, and the predetermined valve opening is When changing the valve opening of the electric expansion valve based on the temperature difference on the evaporator side, the valve opening of the electric expansion valve given at the time of starting the compressor is changed to A method for controlling a 1-cycle refrigeration cycle, characterized in that the start-up time of the compressor is made equal to the start-up time of the compressor that is repeated during the refrigeration cycle operation. (2) A patent claim characterized in that the valve opening degree of the electric expansion valve at the time of repeatedly starting the compressor during the above-mentioned refrigeration cycle operation is set to the same valve opening degree as before the compressor is stopped. A method for controlling a refrigeration cycle according to scope 1.