JPH04258579A - proportional control valve - 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]

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 1
4 decreases, and the piston 10 overcomes the second spring 18 due to the pressure difference between the back pressure chamber 14 and the primary chamber 13 and is pushed up, and at the same time, the valve body 11 separates from the valve seat 17 and the outflow passage 5 An opening is formed. 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. That is, 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 4, 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, when the current flowing through the coil is increased, the current exceeds max (the shaded area above max in FIG. 5(b)) due to the superimposition of a minute alternating current signal, which increases the load.

The present invention solves such conventional problems by reducing 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, thereby increasing the maximum power by reducing the amplitude of the minute alternating current signal. The purpose is to maintain the same level as when no signals are superimposed.

[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 present invention includes an alternating current signal generating means that superimposes an alternating current signal on the current by reducing the amplitude in a region where the driving signal is large.

[0009]

[Operation] With the above-described configuration, the present invention superimposes a minute alternating current signal on a drive signal, while making the maximum power used equal to that when the minute alternating current signal is not superimposed.

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 the 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, if this minute alternating current signal simply has a constant amplitude and a constant frequency, the drive current will increase due to the superposition of this minute alternating current signal, and will exceed the maximum current value near the maximum current value. (Shaded area in FIG. 5(b)) This increases the burden on the power supply.

Therefore, the present invention takes the following measures to prevent the above phenomenon. In a region where the drive current is small, even if a minute alternating current signal is superimposed, the maximum power is not affected. As the drive current increases, it becomes necessary to reduce the power. Therefore, the setting means 22 and the flow rate detection means 23
The valve control means 24 which receives the signal calculates the control amount and outputs a signal to the drive amount setting means 25. 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 decreases the amplitude of the minute AC signal it outputs as the drive current increases in accordance with this control amount.

For example, if a minute alternating current signal (FIG. 3(a)) is superimposed, the amplitude is large when the drive current is small, and the amplitude decreases almost proportionally as the drive current becomes large.
The combined drive current is as shown in FIG. 3(b). Therefore, at the maximum current value (the max point in FIG. 3(b)), there is no superimposed minute AC signal, and the maximum power can be suppressed to the same level as when no minute AC signal is superimposed.

In addition, when it is desired to superimpose a minute alternating current signal without deteriorating the valve characteristics, the amplitude is kept constant until the drive current exceeds a certain value (point a) as shown in FIG. 3(c). The amplitude is made to decrease almost proportionally from max to the maximum value max. The combined drive current is as shown in FIG. 3(d).

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

Furthermore, if only the maximum current value is to be considered, the upper limit of the amplitude of the superimposed minute alternating current signal may be reduced. As shown in Figure 3(g), the upper limit of the amplitude of the AC signal is y
, let the lower limit be x. The combined drive current is shown in Figure 3 (h
), the drive current is below max even near the maximum current, and a minute alternating current signal can also be superimposed.

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, by reducing the superimposed minute AC signal in the region where the drive current of the electromagnetic force generating means is large, the maximum power can be increased compared to the case where the minute AC signal is not superimposed. can be kept at the same level. This eliminates the need to increase the burden on the power supply section that supplies power. This method can also be readily applied to conventional proportional control valves.

[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), (e), (g) are respective output characteristic diagrams (b), (d), (f), (
h) is each output characteristic diagram 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 alternating current signal that superimposes the alternating current signal on the drive signal by reducing the amplitude in a region where the current (drive signal) to the electromagnetic force generation means is large; Proportional control valve with generating means.