JPH0777361A - Electrical expansion valve control device - Google Patents

Abstract

PURPOSE:To carryout a safe operation by a method wherein an electrical expansion valve control device used as an adjusting mechanism in an air conditioner comprises a control means for changing an amount of varying degree of opening in response to the present degree of opening of the expansion valve so as to restrict a rapid variation of flow rate of refriger ant. CONSTITUTION:A rational degree of superheating (a set degree of superheating) is set, and an initial value of difference between a degree of superheating and a set degree of superheating is set to a proper value. Outputs of each of refrigerant temperature sensors 6 to 8 are read into a temperature measuring means 9 to measure a compressor suction refrigerant temperature and an evaporating temperature (during a cooling operation, a middle refrigerant temperature at an indoor side heat exchanger 3 and during a heating operation, a middle refrigerant temperature at an outdoor side heat exchanger 5). Then, a degree of superheating is calculated by a calculation means 10 in reference to a difference between the compressor sucking refrigerant temperature and the evaporating temperature, and at the same time, a difference between the degree of superheating and the set degree of superheating is calculated, and a difference between the calculated difference and the difference value stored in the last controlling operation is calculated. A fuzzy calculation is carried out with these data being applied as a previous condition so as to calculate a PMV degree of opening variation rate, the calculated value is multiplied by the present degree of opening of the electrical expansion valve 4 and then a controlling amount is determined.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric expansion valve control device for controlling an electric expansion valve used in an air conditioner such as a room air conditioner.

[0002]

2. Description of the Related Art An electric expansion valve (hereinafter, PM) is used as a throttle mechanism.
(Also referred to as V), a refrigeration cycle of an air conditioner includes a compressor, a four-way valve, an indoor heat exchanger, an electric expansion valve, and an outdoor heat exchanger connected by a refrigerant pipe, and a four-way valve is used to flow the refrigerant. There is a system in which the operating states of cooling and heating are switched by changing the direction of. In the conventional electric expansion valve control in such an air conditioner, the opening change amount is determined according to the degree of superheat, the compressor discharge temperature, etc., regardless of the current opening.

[0003]

In the conventional electric expansion valve control, the opening change amount is determined according to the degree of superheat, the compressor discharge temperature, etc. regardless of the current opening, so that the PMV opening is small. In the region, the rate of change of the PMV opening with respect to the same control amount is larger than in the region where the opening is large, so that there is a problem that the refrigerant flow rate fluctuates and the refrigeration cycle becomes unstable.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an electric expansion valve control device capable of stably operating the refrigeration cycle by preventing the rapid change of the refrigeration cycle temperature.

[0005]

To solve the above problems, the present invention provides an electric expansion valve control device for controlling an electric expansion valve used as a throttle mechanism in an air conditioner,
The gist of the present invention is to have a control unit that changes the opening change amount according to the current opening of the electric expansion valve.

[0006]

By controlling the opening change amount according to the current opening of the electric expansion valve, it is possible to prevent a sudden change in the refrigerant flow rate and stabilize the refrigeration cycle.

[0007]

Embodiments of the present invention will be described below with reference to FIGS. In this embodiment, fuzzy calculation is applied to determine the PMV opening change amount. In FIG. 1, 1 is a compressor, 2 is a four-way valve, 3 is an indoor heat exchanger, 4 is an electric expansion valve, 5 is an outdoor heat exchanger, and these are connected by a refrigerant pipe to connect an air conditioner. A refrigeration cycle is configured. 6 is a compressor suction refrigerant temperature sensor, 7 is an indoor heat exchanger intermediate refrigerant temperature sensor, 8 is an outdoor heat exchanger intermediate refrigerant temperature sensor, and the output of each of these sensors is sent to the temperature measuring means 9 for compression. The temperature of the refrigerant sucked into the machine and the temperature of the intermediate refrigerant of each heat exchanger are measured. 10
Is a calculation means such as fuzzy as a control means, 11 is a PMV
Opening / closing means, 12 is a numerical value storage means, and 13 is a time measuring means. FIG. 3 shows a membership function and a fuzzy rule of the fuzzy operation performed by the fuzzy or similar operation means 10. In FIG. 3, SH is a target set superheat degree, and ΔSH is a set superheat degree S in the PMV control time interval.
A change amount of H, ΔPLS, is a PMV opening change rate determined by fuzzy calculation.

Now, in the refrigeration cycle shown in FIG. 1, an electric expansion valve 4 having 0 pulses when fully closed and 250 pulses when fully opened is used. The electric expansion valve 4 sucks in the compressor. The opening degree is controlled according to the degree of superheat represented by the difference between the refrigerant temperature and the intermediate refrigerant temperature of the heat exchanger serving as the evaporator. Table 1 shows a control example of the electric expansion valve at this time in comparison with the conventional electric expansion valve control.

[0009]

[Table 1] Present Example PMV opening degree of opening change rate Opening degree of change 250 pulses 5% → 13 pulses 50 pulses 5% → 3 pulses Comparative example Current PMV opening degree of opening change rate of opening change rate 250 Pulse 5 pulse → 2% 50 pulse 5 pulse → 10% In the comparative example, when the electric expansion valve is closed by, for example, 5 pulses with respect to the detected degree of superheat, the current opening is 25 when fully opened.
Whether the number of pulses is 0 or the number of pulses is 50 with a small opening, the amount of change in opening is 5 pulses. Therefore, the opening change rate, which is the ratio of the opening change amount to the current opening, increases in the region where the current opening is small, and the refrigerant flow passage area in the electric expansion valve changes abruptly. Fluctuations become more intense, making it difficult to stabilize the refrigeration cycle. On the other hand, in the present embodiment, the opening change rate is determined with a constant opening change rate with respect to the current opening (5% as an example), so that a rapid refrigerant flow rate fluctuation is less likely to occur and the refrigeration cycle is stabilized. Is possible.

Next, the procedure of electric expansion valve control will be described with reference to the control flowchart of FIG. First, an ideal superheat degree (set superheat degree) is set (step 21), and an initial value of a difference Tsh between the superheat degree and the set superheat degree is set to an appropriate value (step 22). The outputs of the respective refrigerant temperature sensors 6, 7, 8 are read into the temperature measuring means 9 and the compressor suction refrigerant temperature and the evaporation temperature (intermediate refrigerant temperature of the indoor heat exchanger during cooling and the outdoor heat exchanger during heating). Is measured (step 23). The calculation means 10 such as fuzzy calculates the superheat degree from the difference between the compressor suction refrigerant temperature and the evaporator temperature, and calculates the difference Tsh between the superheat degree and the set superheat degree (steps 24 and 25). The value of Tsh at this time is stored in the numerical storage means 12 (step 26). Difference Δ between the calculated Tsh and the Tsh stored in the numerical value storage means 12 during the previous control.
Tsh is calculated (step 27). Then, Tsh, Δ
Fuzzy calculation is performed using Tsh as an antecedent, PMV opening change rate ΔPLS is calculated, and the control value (PMV opening change amount) is determined by multiplying the value by the current opening of the electric expansion valve, and PMV opening / closing means 11 (steps 28 to 3)
0). After a certain time (control interval time) has passed by the time measuring means 13, temperature measurement is started (step 31). Then, the above operation is repeated.

[0011]

As described above, according to the present invention,
Since the control means for changing the opening degree according to the current opening degree of the electric expansion valve is provided, even in the range where the current opening degree is small in the usual electric expansion valve control, a rapid refrigerant flow rate fluctuation is less likely to occur and the refrigeration cycle is reduced. Can be operated stably.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an electric expansion valve control device according to the present invention.

FIG. 2 is a control flowchart for explaining a control procedure of the above embodiment.

FIG. 3 is a diagram showing a fuzzy control membership function and a fuzzy rule in the embodiment.

[Explanation of symbols]

 4 Electric expansion valve 10 Fuzzy and other computing means (control means) 11 PMV opening / closing means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takayoshi Iwanaga 8 Shinsita-cho, Isogo-ku, Yokohama, Kanagawa Prefecture

Claims (1)

[Claims] 1. An electric expansion valve control device for controlling an electric expansion valve used as a throttle mechanism in an air conditioner, comprising control means for changing an opening change amount according to a current opening amount of the electric expansion valve. An electric expansion valve control device characterized by: