JPH04258578A - proportional control valve - Google Patents

Abstract

PURPOSE:To stably operate a proportional control valve for controlling flow rate of fluid by changing the amplitude of a minute alternating signal. CONSTITUTION:A control means 20 provides action for denying increasing friction force to an electromagnetic force generating means 21 when a valve body 11 or a cylinder 7 is pressed to a valve case body 6 by enlarging piled up minute alternating signals in a range in which the driving current for the electromagnetic force generating means 21 is large.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a proportional control valve for controlling the flow rate of fluid.

0002

2. Description of the Related Art Conventionally, there has been a proportional control valve of this type as shown in FIG. In FIG. 4, a valve body includes a coil 1, a plunger 2 that slides inside the coil 1, a first spring 3 that biases the plunger 2 in a direction to push the plunger 2 to the outside, an inlet passage 4, and an outlet passage 5. It has a body 6 and a cylinder 7 that slides inside the valve body 6. This cylinder 7 has a plurality of adjustment holes 8 and is interlocked with the plunger 2. The flow rate of the liquid flowing from the circumferential direction toward the center of the cylinder 7 is adjusted by the area of the adjustment hole 8 of the cylinder 7 facing the inflow path 4.

A piston 10 which is a pressure receiving body 9 provided in the cylinder 7, and a valve body 1 which constitutes an opening to the outflow passage 5.
1 and the valve shaft 12 are integrally constructed. A back pressure chamber 14 is partitioned off from the primary chamber 13 of the inflow passage 4 while leaking slightly from around the piston 10, and a back pressure chamber 14 is formed in the valve shaft 12.
A communication hole 16 is provided which communicates the secondary chamber 15 which is connected to the outflow path 5 downstream of the valve body 11. The piston 10 is provided with a second spring 18 that urges the valve body 11 in a direction to abut the corresponding valve seat 17. Further, the valve shaft 12
A pilot valve 19 that opens and closes the communication hole 16 is provided on the side of the back pressure chamber 14 inside, and the pilot valve 19 is connected to the plunger 2.

When the coil 1 is energized, the plunger 2 is attracted against the urging force of the first spring 3, the pilot valve 19 is lifted, and the communication hole 16 is opened. At that time, back pressure chamber 14
The pressure of the piston 10 decreases, and the piston 10
The second spring 18 is overcome by the differential pressure of 3, and the valve element 11 is simultaneously separated from the valve seat 17 to form an opening to the outflow passage 5. When the energization of the coil 1 is further increased, the lift amount of the pilot valve 19 is increased, and the cylinder 7 is lifted, so that the adjustment hole 8 of the cylinder 7 faces the inflow path 4, and the inflow from the circumferential direction of the cylinder 7 toward the center. The flow rate of fluid begins to increase. In other words, by adjusting the value of the current flowing through the coil 1, a change in the lift amount of the cylinder 7 results in a change in the area of the adjustment hole 8 of the cylinder 7 facing the inflow path 5, thereby adjusting the flow rate of the fluid.

The control means 20 superimposes a minute alternating current signal when passing current through the coil 1. This is to reduce the hysteresis characteristic of the magnetic circuit consisting of the coil 1 and the plunger 2 and the sliding resistance at the start of driving.

[0006]

However, in the above configuration, the minute alternating current superimposed on the coil current is constant regardless of the magnitude of the coil current, as shown in FIG. 5(a). For this reason, in a region where the current flowing through the coil is large, the valve is close to being fully open, and the generated force is large and the frictional force also increases. Even in this region, if the amplitude of the superimposed minute alternating current signal is constant, the increase in sliding resistance cannot be absorbed, and the valve will not operate stably.

The present invention solves such conventional problems by increasing the amplitude of the superimposed minute alternating current signal in a region where the current (drive signal) to the electromagnetic force generating means is large. The purpose is to operate the valve stably regardless of the situation.

[0008]

[Means for Solving the Problems] In order to solve the above problems, the proportional control valve of the present invention includes a valve body having an inflow passage and an outflow passage, an electromagnetic force generating means, and a biasing force of the electromagnetic force generating means. The valve body slides inside the valve body to adjust the flow rate, and the control means adjusts the current of the electromagnetic force generation means, and the control means controls the current (
The device is equipped with AC signal generating means that increases the amplitude in a region where the drive signal is large and superimposes the AC signal on the drive signal.

[0009]

[Function] With the above-described structure, the present invention increases the amplitude of the drive signal using the superimposed minute alternating current signal in the vicinity of the fully opened valve, where the sliding friction of the valve increases and force is required.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. Note that FIG. 1 is a cross-sectional view of a proportional control valve, and parts that are the same as those in FIG. The coil 1 and the plunger 2 form an electromagnetic force generating means 21. 22 is a setting means for setting a flow rate, and the flow rate is detected by a flow rate detection means 23.

FIG. 2 shows an example of the control means 20. By inputting the signals from the setting means 22 and the flow rate detection means 23, the valve control means 24 calculates a control amount and outputs a signal to the drive amount setting means 25. At this time, a signal is also sent to the AC signal generating means 26 to generate a minute AC signal to be superimposed. Drive amount setting means 2
The output (drive current) of 5 is transmitted to the electromagnetic force generating means 21.

Next, the operation of the configuration of the present invention will be explained. The flow rate is adjusted by the current flowing through the electromagnetic force generating means 21 in the same way as explained in the related art. The control means 20 inputs the signal from the flow rate detection means 23 and the signal from the setting means 22 to control the electromagnetic force generation means 21 so that the flow rate becomes the set flow rate.
The amount of lift of the cylinder 7 is changed by varying the current flowing through the cylinder 7, and the flow rate of the fluid is adjusted by changing the area of the adjustment hole 8 of the cylinder 7 facing the inflow path 5. At this time, if the current flowing through the electromagnetic force generating means 21 is a direct current, it is difficult to move the cylinder 7 quickly and adjust the flow rate due to the hysteresis characteristics of the magnetic circuit consisting of the coil 1 and the plunger 2 and the sliding resistance at the start of driving. . For this reason, usually a minute AC signal is superimposed on the drive signal,
This hysteresis characteristic and sliding resistance at the start of driving are reduced.

However, in a region where the current flowing through the electromagnetic force generating means 21 is large, the valve is close to being fully open, and the force applied to the valve body is large and the frictional force is also increased. Even in this region, if the amplitude of the superimposed minute alternating current signal is constant, the increase in sliding resistance cannot be absorbed, and the valve will not operate stably.

Therefore, the present invention takes the following measures to prevent the above phenomenon. As the drive current increases, the flow rate also increases, and the valve body 11 and cylinder 7 are pressed against the valve housing body 6 due to fluid force, etc., and the frictional force increases.

The valve control means 24 inputs the signals from the setting means 22 and the flow rate detection means 23, calculates a control amount, and outputs a signal to the drive amount setting means 25. At this time, since the control amount and the drive current correspond almost as a pair, this control amount is also output to the AC signal generating means 26. The AC signal generating means 26 increases the amplitude of the minute AC signal it outputs as the drive current increases in accordance with this control amount.

For example, when a minute AC signal (FIG. 3(a)) is superimposed, the amplitude is small when the drive current is small, and the amplitude increases almost proportionally as the drive current becomes large, the combined drive current becomes as shown in FIG. b) Therefore, even if the superimposed minute alternating current signal increases near the maximum current value (the max point in FIG. 3(b)) and the sliding resistance of the cylinder 7, etc. increases, it is possible to supply the electromagnetic force generating means 21 with the effect of canceling it. can.

In addition, if it is desired to superimpose a certain amount of minute AC signal from a region where the drive current is small without deteriorating the valve characteristics, the drive current may be set to a certain value (
The amplitude is constant until it exceeds point a), and from point a to the maximum value m
The amplitude is made to decrease almost proportionally up to ax. The combined drive current is as shown in FIG. 3(d).

Similarly, the amplitude of the minute alternating current signal may be kept constant until the drive current exceeds a certain value (point b) as shown in FIG. 3(e), and the maximum amplitude may be applied when the drive current exceeds point b. The combined drive current is as shown in FIG. 3(f).

Further, in the above embodiment, a coil and a plunger are used as the electromagnetic force generating means, but a structure using a coil and an iron core may be used, and a magnet may be provided in the cylinder to transmit the biasing force in a non-contact manner.

[0020]

As described above, according to the proportional control valve of the present invention, in a region where the drive current of the electromagnetic force generating means is large, by increasing the superimposed minute AC signal, the sliding of the cylinder etc. is reduced near the maximum current value. Even if dynamic resistance increases due to fluid force or the like, it is possible to supply the electromagnetic force generating means with an action to cancel it. Therefore, the valve can be operated stably regardless of the flow rate (position of the valve body).

[Brief explanation of the drawing]

[Fig. 1] A sectional view showing an embodiment of the proportional control valve of the present invention.

[
Figure 2: Control block diagram of proportional control valve

[Figure 3] (a),
(c) and (e) are respective output characteristic diagrams of the AC signal generation means for the same drive current I. (b), (d), and (f) are respective output characteristic diagrams of the drive amount setting means for the same drive current I.

[Figure 4] Cross-sectional view of a conventional proportional control valve

[Figure 5] AC signal characteristic diagram

[Explanation of symbols]

4 Inflow path 5 Outflow path 6 Valve body 7 Cylinder 20 Control means 21 Electromagnetic force generation means 26 AC signal generation means

Claims (1)

[Claims] 1. A valve body having an inflow path and an outflow path, an electromagnetic force generating means, a valve body that slides inside the valve body by the biasing force of the electromagnetic force generating means to adjust the flow rate, and the valve body that adjusts the flow rate. control means for adjusting the current of the electromagnetic force generation means; the control means generates an AC signal that increases the amplitude in a region where the current (drive signal) to the electromagnetic force generation means is large and superimposes the AC signal on the drive signal; Proportional control valve with generating means.