JPS6098276A - Control of electrical valve - Google Patents

Abstract

PURPOSE:To obtain the rectilinear relation between the applied voltage and the air flow-rate by applying the standard pulse group of the effective values of the square impact wave at time intervals into the electric conduction part of an electric valve equipped with a decompression mechanism. CONSTITUTION:A coolant circuit A is equipped with refrigeration parts such as an electrical coolant compressor 1, condenser 2, electrical valve 3 equipped with decompression mechanism, and an evaporator 4 annularly connected through piping, and used for cooling a cooled-side load 5. An electric circuit is constituted of a control center part 6, photocoupler 8 set between a primary side 7A and a secondary side 7B, PNP transistors 9 and 10, interface part 7 equipped with fixed resistances 11-13, and an output part 14. The effective value of the square impact wave is applied as an applied voltage into the electric conduction part of the electrical valve 3 from the output part 14. Therefore, a rectilinear flow-rate characteristic can be obtained in a wide range, and stable control is permitted.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial field of application The present invention is applicable to air cylinders, refrigeration of refrigerators, thermoelectric expansion valves used in air conditioning equipment buttons, reversible electromagnetic proportional valves, etc., and control of electric valves with pressure reducers and grooves. Regarding the method.

(b) Prior art This type 'F11. The valve train is introduced in Japanese Patent Publication No. 7869/1986 as a "bimetallic heat-responsive valve with electric heating means." There are two types of electric valves: an energized closed type and an energized open type. ), pages 60 to 64.

The basic operating characteristics of the electric valve described above are the relationship between the voltage applied to the heater, which is the current-carrying part, and the refrigerant flow rate. Figure 2 on page 61 of the above publication shows the flow characteristics of the energized closed valve type and the energized open valve type, both of which can theoretically be controlled over a wide range from fully closed to fully open, but in practice. When used in applications, the linear portion of the flow rate characteristics is used to simplify the control method.

In other words, in the control method described above, since the voltage applied to the current-carrying part is an analog voltage, the flow rate characteristic becomes a curve as a whole, and as a result, control can only be performed within a narrow range of the linear portion of this curve. Ta.

Therefore, the inventor of the present application has developed an energized closed-valve electric valve (thermoelectric expansion valve) SQX-22012D (differential pressure i
An experiment was carried out to confirm the above flow rate characteristics using the following:

The experimental results are shown in Figure 1. In the KN experiment, considering that there is a unique relationship between the refrigerant flow rate and the air flow rate in both fluids, even if the refrigerant flow rate is replaced with the air flow rate, the characteristics will not be impaired. Air flow was used as the fluid passing through the valve.

According to the experimental results, there was almost no linear relationship between the analog voltage (applied voltage) E, which was the controlled variable, and the air flow Jll GA, which was the manipulated variable, and the air flow characteristics were a curve. . In other words, in order to change the flow rate of refrigerant entering the electric valve as the load to be cooled in a refrigeration system, such as a refrigerator, increases or decreases internal self-defense, if the analog voltage E is changed in accordance with this change, the Change of the same control amount △E due to occasional analog voltage E, for example, the manipulated amount △ for 0.5VK
The changes in GA appear as shown in FIG. 1 and the table below.

In this way, even if the change in the control amount △E of the analog voltage E applied to the current-carrying part is the same, the value of the manipulated variable △QA changes. It was difficult to determine the amount ΔGA (adjust the valve opening), that is, it was difficult to control the curved portion of the flow rate characteristic, and the drawbacks mentioned in the above publications were confirmed.

(c) Purpose of the Invention The present invention solves the drawbacks of the prior art and expresses the relationship between the controlled amount (applied voltage) and the manipulated amount (air flow rate) in a straight line, making it possible to easily control the electric valve. The purpose is to

(B) Structure of the Invention A method for controlling a motor-operated valve comprising applying a reference pulse group of the effective value of a rectangular shock wave, which is a type of strain wave, at time intervals to the current-carrying part of the motor-operated valve with a pressure reducing mechanism.

(E) Embodiment of the Invention Figure 2 shows a control circuit for a refrigeration system, showing a refrigerant circuit (4) and an electric circuit (Bl).
11. Consists of buttons to connect refrigeration components such as a condenser (2), the above-mentioned known electric valve with a pressure reducing mechanism (3), and an evaporator (4) in a ring shape through piping to form a predetermined refrigeration cycle. to cool the load to be cooled (5).

The electric circuit includes a control center (6) consisting of a microprocessor, a photocoupler (8) spanning the primary side (7A) and the secondary side (7B), and a PNP transistor (
9) Consists of an interface part (7) with Ql, fixed resistance Ql) Q7J (13), and an output part (14), and from the output part (14), the effective value of the square shock wave is applied as the voltage to the electric valve (3). to the current-carrying part.

In order to improve the controllability of the electric valve, it is sufficient if the relationship between the controlled amount (applied voltage E) and the manipulated amount (air flow rate GA) can be expressed as a linear relationship. For example, if the following expression GA=G(MAX)-kB is obtained, the situation in which the change in the manipulated variable ΔQA depends on the magnitude and position of the controlled variable E can be eliminated.

In order to obtain the above applied voltage equivalent value E, the waveform must be set to HIGH.
It is necessary to use the DC voltage equivalent value of the effective value depending on the length of time, that is, the effective value voltage of the rectangular shock wave.

FIG. 3 shows the waveform and effective value of the square shock wave. From these drawings, the applied voltage equivalent value Ee (V) is Ee = EH5 (D).

Next, applied voltage E [■] vs. air flow rate GA (:M'/H)
Analyze.

When the curve in FIG. 1 is approximated, it becomes approximately the following equation.

GA = GA CM A ``2 + +'', and the better the ratio of the flow rate depending on the magnitude of the voltage becomes a partial pressure, the larger the change in the air flow rate becomes, and the more difficult it becomes to control the electric valve (3).

Next, to explain the applied voltage vs. air flow rate given by the effective value of the square shock wave, by substituting the above equation 0 into the equation 0, we get GA ;= GA[MAX)-4,E2-〇AP:MA
X:)−, (EHL〒)”= GA, (MAX)
−, Eix”/7= GA (MAX) ”s
The formula τ □■ (ks''' + E = 1) is obtained.According to this formula, the air flow rate QA is HIG of the rectangular shock wave) (obtained as a linear formula for time τ, and the above formula 0 This improves controllability.

The configuration of the rectangular shock wave of order K is represented by specific numerical values. However, τ
6: Reference pulse: The period was set to 5 m5 ec, and the HIGH time τ was made so that the number of reference pulses could be treated as a group. As a result, 0≦N≦200 [pieces/second] and O≦Ee≦114
It becomes [■].

The waveform in this state is as shown in FIG. 4, and its effective value Ee is as shown in FIGS. 4 and 5.

Also, looking at the relationship between the number of pulses of the square shock wave and the air flow rate QA from the above equation 0, QA2GA (MAX) -k, τ2GA (MAXI -ksX(NTg) = GA (
MAXl-kt N (kt" k3τ8) This relationship becomes the air flow rate characteristic shown in Fig. 6,
Air flow characteristics can be represented by a straight line.

Therefore, the 'WL valve train (3) can be controlled from fully closed to fully open, and any part of the flow rate characteristics can be controlled linearly.

(f) Effects Since the present invention applies the effective value of a rectangular shock wave to the current-carrying portion of an electric valve with a pressure reducing mechanism, it produces the effects listed below.

■ The relationship between the controlled amount and the manipulated amount, that is, the flow rate characteristics, is linear over a wide range, making it possible to control the electric valve from fully closed to fully open, and since the flow rate is linear no matter where you take it, it is easy to control within a predetermined range using the button. Moreover, even if there is a variation in the load on the side to be cooled, it can be easily converged, and stable control can be performed as a whole.

■ Even if the controlled variable varies in response to fluctuations in the load on the cooled side, the change in the manipulated variable is approximately constant, so the degree of superheating can be maintained at an optimal state, improving the heat exchange efficiency of the evaporator. .

■ Even if the load on the cooled side changes, the degree of superheat can be maintained at a substantially constant level, reducing the amount of liquid returning to the electric refrigerant compressor, improving the safety of the refrigeration system.

■ Waveform generation is suitable for digital processing, making it easier to construct electrical circuits.

[Brief explanation of the drawing]

FIG. 1 is a flow rate characteristic diagram according to a conventional control method. Fig. 2 is a control circuit diagram of a refrigeration system equipped with an electric valve according to the present invention, Fig. 3 is a basic waveform diagram of a rectangular shock wave, and Fig. 4 is a configuration diagram of a rectangular shock wave according to the present invention. 5 is a reference pulse diagram of FIG. 4, and FIG. 6 is a flow rate characteristic diagram according to the control method of the present invention.

Claims (1)

[Claims] 1. A device characterized in that a reference pulse group of the effective value of a rectangular shock wave, which is a type of strain wave, is applied at time intervals to a current-carrying part of an electric valve with a pressure reducing mechanism. Valve train control method.