JPH0875033A - Flow-meter control valve - Google Patents

Abstract

PURPOSE: To facilitate control of a flow quantity of fluid by slightly transferring a solenoid main body and a plunger relatively. CONSTITUTION: A plunger 133 is slightly oscillated in relation to a solenoid main body 131 by supplying a micro-oscillation current through a coil 132 of the solenoid main body 131 in a control part 130. A plunger 133 is thus rapidly started to move since no moving power large than a large static friction between the solenoid main body 131 and it is required, when moving of the plunger 133 is started. Frequency of the micro-oscillation current is set lower than natural oscillation frequency of the plunger 133 determined by the mass of the plunger 133 and the elastic coefficient of a spring 135 in order to effectively activate the micro-oscillation. Consequently, hysteresis becomes small so as to easily control a flow quantity of the fluid.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow rate control valve for controlling the flow rate of fluid (gas, liquid).

[0002]

2. Description of the Related Art In many measuring devices such as a gas chromatograph and a liquid chromatograph, it is necessary to control the flow rate of a gas sample or a liquid sample as an object to be measured. As a flow rate control valve for that purpose, a solenoid type flow rate control valve that controls the flow rate by moving a plunger, which is a magnetic body, by supplying current to a solenoid to close / open the fluid inlet / outlet or change the opening amount thereof. Is often used.

[0003]

In a solenoid type flow control valve, a plunger is a fluid inlet / outlet (hereinafter referred to as a nozzle).
And the flow rate is changed by changing the distance (gap length) between the plunger and the nozzle. Here, in order to precisely control the flow rate of the fluid, it is necessary to precisely control the position of the plunger.
Therefore, the plunger and its guide must be assembled with very high precision and with almost no play.

However, when the plunger and the guide are tightly assembled in this way, friction between them is inevitably increased. In this case, static friction becomes a particular problem, and even if an electric current is applied to the solenoid to move the plunger, the plunger does not start moving until the force for driving the plunger exceeds the static friction force. Therefore,
The current for driving the plunger and the actual gap length between the plunger and the nozzle show a large hysteresis as shown in FIG. 3A, which makes it difficult to control the flow rate accurately.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a solenoid type flow control valve capable of accurately controlling the flow rate.

[0006]

SUMMARY OF THE INVENTION The present invention, which has been made to solve the above-mentioned problems, is designed to move a plunger with respect to a fluid inlet / outlet by supplying an electric current to a coil of a solenoid, and The flow control valve for controlling the amount is characterized by including a minute vibration applying means for relatively minutely vibrating the solenoid body and the plunger.

[0007]

In order to start the plunger from the state in which it is stationary with respect to the fluid inlet / outlet, the static friction of the contact portion between the plunger and the solenoid body (the solenoid body here includes the guide) is exceeded. There is a need. When the static friction is large, hysteresis occurs as described above, but in the flow control valve according to the present invention, the plunger and the solenoid body are constantly vibrating relatively relatively, so the plunger needs to exceed the static friction. Without, you can start moving immediately. Therefore, the driving current of the solenoid and the gap length have extremely small hysteresis as shown in FIG.

The minute vibration may be applied during the movement of the plunger with respect to the fluid inlet / outlet.

[0009]

FIG. 4 shows a gas chromatograph apparatus using the flow control valve of the present invention. In the gas chromatograph apparatus, the pressure of the carrier gas supplied to the column 16 is first adjusted by the pressure adjuster 11, and the flow rate is controlled by the flow rate control valve 13. The flow rate of the carrier gas is detected by the flow rate sensor 12, and the detection result is fed back to the flow rate control valve 13, whereby the column flow rate is precisely controlled. The carrier gas passes through the filter 14 and then the column 16 via the injector 15. By injecting the sample from the injector 15, the sample rides on the carrier gas and passes through the column 16, where the components are separated and each component is detected by a detector (not shown). A part of the sample and the carrier is discharged from the split valve 17.

In order to perform accurate analysis in such a gas chromatograph, it is necessary to precisely control the flow rate of the carrier gas. In this embodiment, a solenoid type flow control valve 13 as shown in FIG. 5 is used as the flow control valve 13 for this purpose. This flow control valve 13 is
The coil 132 is wound inside the solenoid body 131,
A plunger 133 is movably arranged at the center thereof. The plunger 133 is arranged in a guide hole formed inside the solenoid main body 131 with a very small gap provided, whereby the plunger 133 can be precisely moved up and down in FIG.

An airtight chamber 139 is attached to the solenoid body 131, and a gas inlet 138 and a gas outlet 1 are provided on the chamber wall.
37 is provided. Indoor side end 1 of gas outlet 137
36 is formed in a nozzle shape and is arranged in the vicinity of the plunger 133. Plunger 1 facing this nozzle 136
A rubber sheet 134 for maintaining airtightness when closing the nozzle 136 is provided on the lower surface of 33. The gas inlet and the gas outlet may be reversed.

Plunger 133 and solenoid body 131
A spring 135 is provided between and, so that the plunger 133 is always pressed against the nozzle 136 (that is, the gas outlet 137 is always closed). From the control unit 130 of the flow control valve 13 to the coil 132
When an exciting current is supplied to the coil 132, the magnetic field formed by the coil 132 pulls the plunger 133 upward in FIG. 5 against the force of the spring 135 and opens the nozzle 136. As a result, the gas supplied from the gas inlet 138 into the airtight chamber 139 can be discharged, and a gas flow path is formed. In addition, the distance between the plunger 133 and the nozzle 136 can be controlled by adjusting the current flowing through the coil 132, and the gas flow rate can be controlled.

However, since the plunger 133 is in contact with the solenoid body 131 as described above, when the movement of the plunger 133 is started from the stationary state, the static friction of the contact portion must be exceeded. Therefore, in the flow control valve 13 of the present embodiment, the control unit 130 constantly supplies the coil 132 with the minute oscillating current as shown in FIG. And let it vibrate slightly. Therefore, when the movement of the plunger 133 is started, it is not necessary to exceed a large static friction with the solenoid body 131, and the plunger 133 immediately starts to move.

When opening and closing the nozzle 136, the control unit 13
0 is usually a drive current as shown in FIG.
However, in the case of the flow rate control valve 13 of the present embodiment, a minute oscillating current is supplied while the movement of the plunger 133 is stopped, as shown in FIG. 1 (c). Here, in order to make the microvibration work effectively, the frequency of the microvibration current depends on the mass of the plunger 133 and the spring 135.
Is lower than the natural vibration frequency of the plunger 133 determined by the elastic constant of. Further, the amplitude of the minute oscillating current while the plunger 133 is closing the nozzle 136 is
It is appropriate to set the vibration amount such that the rubber sheet 134 of the plunger 133 keeps closing the nozzle 136 within the range of its elasticity.

As shown in FIGS. 2 (a) and 2 (b),
The minute oscillating current may be superposed while the plunger 133 moves with respect to the nozzle 136. In addition, in FIGS. 1 and 2, the duty ratio of the minute oscillating current is 50%.
However, this may be changed. Further, the shape of the pulse of the minute oscillating current may be sinusoidal instead of rectangular.

A second embodiment of the present invention is shown in FIG. In the above embodiment, the plunger 133 is vibrated by supplying a minute current to the coil 132. However, in the flow control valve 13 of this embodiment, the vibration cam 1 is provided outside the solenoid body 131.
4 is provided to apply mechanical vibration to the solenoid body 131. Then, the frequency of this vibration is set to the plunger 13
It is set higher than the frequency of the natural vibration of the plunger determined by the mass of 3 and the elastic constant of the spring 135. As a result, the solenoid body vibrates with respect to the plunger 133.

Although the gas flow rate control valve has been described in each of the above embodiments, the flow rate control valve according to the present invention can be similarly applied to the case of controlling the flow rate of liquid.

[0018]

In the flow rate control valve according to the present invention, the plunger and the solenoid main body are constantly vibrating relatively relatively, so that the plunger does not need to exceed the static friction and the movement can be started immediately. Therefore, the hysteresis is extremely small, and the accurate control of the flow rate becomes easy.

[Brief description of drawings]

FIG. 1 is a graph showing a waveform of a current applied to a coil of a flow control valve according to a first embodiment.

FIG. 2 is a graph showing another example of the current waveform applied to the coil of the flow control valve.

FIG. 3 is a graph showing hysteresis of plunger movement according to the related art (a) and the present invention (b).

FIG. 4 is a schematic configuration diagram of a gas chromatograph device.

FIG. 5 is a sectional view of the flow rate control valve of the first embodiment.

FIG. 6 is a sectional view of a flow control valve according to a second embodiment.

[Explanation of symbols]

 13 ... Flow control valve 130 ... Control part 131 ... Solenoid body 132 ... Coil 133 ... Plunger 134 ... Rubber sheet 135 ... Spring 136 ... Nozzle 137, 138 ... Gas inlet / outlet 139 ... Airtight chamber

Claims (1)

[Claims] 1. A flow control valve for controlling the amount of fluid passing through a fluid inlet / outlet by moving the plunger with respect to the fluid inlet / outlet by supplying an electric current to a coil of a solenoid. A flow control valve comprising a microvibration applying means for causing microvibration.