JPS60245885A - Flow control valve - Google Patents

Abstract

PURPOSE:To obtain a flow control valve having a good response characteristic, by providing a needle part, which controls a flow of fluid flowing in a clearance between a valve seat and the needle part, and a piezo-electric element which displaces the needle part for the valve seat. CONSTITUTION:When a flow of fluid to be transferred increases larger than the preset value, large voltage Vc from a comparing control circuit 17 in a flow meter 9 is applied to a piezo-electric element 5 in a control valve 1 through lead wires 18. The piezo-electric element 5, generating a distortion by applying the voltage Vc, is instantaneously extended by a fine dimension and displaced in the direction of an arrow head A. Consequently, a needle part 6 approaches a valve seat 2 through a supporting member 7 in a good response to a signal from the flow meter 9, and the flow of fluid is controlled to the preset value by narrowing a clearance between a control part 6a and the valve seat 2 so as to throttle a valve opening and reduce the flow of fluid.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a flow rate control valve, and in particular to a method for controlling the flow rate of fluid flowing between the valve seat and the valve seat by displacing a needle portion provided opposite to the valve seat. related to flow control valves.

Conventional technology Conventionally, as a flow rate control valve that controls a small flow rate of fluid, the flow rate of the fluid is measured using a thermal mass flowmeter, and this measured value is compared with the set value of the desired supply flow rate to determine the measured value. If the difference is large, the storage pipe that houses the heated nichrome wire will thermally expand due to the supply of voltage according to the difference, and the needle at the tip of the storage pipe will be displaced toward the valve seat and the fluid flow rate will be reduced to a minute flow rate. In addition, if the measured value is smaller than the set value, the voltage supply to the nichrome wire is stopped, the storage pipe is cooled by the fluid supplied around the storage pipe, the storage pipe is contracted, and the needle part is separated from the valve seat to reduce the flow rate. The valve opening was adjusted to increase the flow rate, thereby controlling the flow rate. However, with conventional flow control valves, the storage pipe is heated to expand or cooled to contract, so it takes time to displace the needle, and the response of the flow control valve is slow, making it difficult to perform accurate flow control. This method is difficult, and furthermore, since the storage pipe is cooled by a controlled fluid, the fluid may be heated and physical properties may change, which is undesirable.

Means for Solving the Problems The object of the present invention is to provide a flow control valve that eliminates the above-mentioned drawbacks, and is configured such that the valve limb is disposed opposite to the valve limb and its displacement causes the flow control valve to displace the valve seat. It consists of a needle part that controls the flow rate of fluid flowing therebetween, and a piezoelectric element that displaces the needle part with respect to the valve seat by applying a voltage.

Example FIG. 1 shows a first embodiment of a flow control valve according to the present invention.

In the figure, a flow control valve 1 has a valve body 3 having a tapered valve seat 2, and an upper opening of the valve body 3 covered by a lid 4. A piezoelectric element 5 is fixed to the inner recess 4a of the lid 4, which is slightly displaced in the direction of extension when a voltage is applied. 6 is the needle part,
The conical portion 6a at the tip is fitted into the valve seat 2, and is fixed to the piezoelectric element 5 via a support member 7. For this reason,
The needle portion 6 can move closer to or away from the valve seat 2 as the piezoelectric element 5 is displaced. Reference numeral 8 denotes a diaphragm made of metal such as stainless steel, whose central part is fixed to the lower part of the piezoelectric element 5 and the upper part of the support member 7, respectively, and whose peripheral part is held between the valve body 3 and the lid 4, and which is connected between the inside of the valve body 3 and the lid. 4. Since the inside of the lid 4 is airtightly sealed by the diaphragm 8, the fluid flowing inside the valve body 3 does not directly adhere to the piezoelectric element 5. Therefore, even if the fluid is a corrosive gas, the piezoelectric element 5 is protected from the gas, and the flow rate control valve 1 can control the flow rate well.

The flow rate of the fluid that passed between the needle part 6 and the valve seat 2 is
It is measured by a thermal mass flow meter 9 installed upstream of the flow control valve 1 shown in FIG. The thermal mass flow meter 9 can accurately measure the flow rate by utilizing the fact that the rate at which the self-heating resistor is cooled by the flow rate of the fluid corresponds to the mass flow rate of the fluid. A pair of detection coils 12 and 13, which are self-heating resistors, are wound around the 10 branch pipes 11. Reference numeral 14 denotes a fluid resistance section that includes a plurality of pipes or laminar flow elements in the longitudinal direction of the pipe, and urges fluid to flow into the branch pipe 11.

In the flow meter 9, when current is passed through the bridge circuit 15, the detection coils 12, 13 are heated, and a certain amount of heat is added to the fluid flowing through the branch pipe 11.

When the control valve 1 is opened and fluid flows in the branch pipe 11, the fluid heated by the upstream detection coil 12 is transferred to the downstream detection coil 13.

Therefore, the temperature TA of the detection coil 12 decreases, and the temperature TB of the detection coil 13 is relatively high such that TA <Te
, the temperature resistance value RA of the detection coil 12 decreases and the temperature resistance value Re of the detection coil 13 relatively increases.
The balance of the bridge circuit 15 is lost and the output voltage VA increases.

The output voltage VA from the bridge circuit 15 is amplified by the amplifier circuit 16 and compared with the set voltage Ve for the desired fluid flow rate by the comparison control circuit 17, and a voltage Vc corresponding to the difference is supplied to the flow rate control valve 1. Therefore, the flow rate control valve 1 is supplied with the voltage Vc from the comparison control circuit 17 to the amplifier circuit 1.
The flow rate is controlled until the difference between the output voltage VA from 6 and the set voltage BEVe becomes zero.

Note that the flow meter 9 measures the minute flow rate of the branch pipe 11, which has a smaller diameter than the main pipe 10, and measures the flow rate of the control valve 1 in terms of the ratio of the cross-sectional area of the main pipe 10 to the cross-sectional area of the branch pipe 11. It is something.

If the flow rate of the fluid to be transferred is greater than the preset set flow rate, a large voltage Vc is applied from the comparison control circuit 17 of the flow meter 9 to the piezoelectric element 5 of the control valve 1 via the lead wire 18; Ru. The piezoelectric element 5 is strained by the application of the voltage Vc, and immediately expands in minute dimensions and is displaced in the direction of the arrow. Therefore, the needle portion 6 is responsive to the signal from the flowmeter 9 and approaches the valve seat 2 via the support member 7, narrowing the gap between the conical portion 6a and the valve seat 2 and opening the valve. throttle to reduce the flow rate and control it to the set flow rate.

In addition, if the fluid flow rate is smaller than the set flow rate, the flow meter 9
A voltage Vc smaller than the above voltage is applied to the piezoelectric element 5 from the comparison control circuit 17 . Since the piezoelectric element 5 is displaced approximately in proportion to the voltage Vc, when the voltage Vc becomes small, the piezoelectric element 5 shrinks to a smaller dimension than described above and is displaced in the direction of the arrow B. For this reason, the needle part 6
is separated from the valve seat 2 via the support member 7, widens the gap between the conical portion 6a and the valve seat 2, increases the flow rate, and controls the flow rate to the set flow rate.

Note that the center portion of the diaphragm 8 bends in the direction of arrows Δ and B following the displacement of the piezoelectric element 5.

FIG. 3 shows a second embodiment of the flow control valve according to the present invention.

In FIG. 3, the piezoelectric element 5 of the flow control valve 20 has its upper part connected to the lid 21.
The needle part 6 is fixed to the inner surface 21a of the needle part 6, and the needle part 6 is fixed directly to the lower part thereof.

The lead wire 18 of the piezoelectric element 5 is inserted through the through hole 21b of the lid 21 to the outside. The through hole 21b is filled with a sealing material 22 made of resin or the like to prevent fluid leakage. Furthermore, a gasket 24 seals between the lid 21 and the valve body 23.

The flow rate control valve 20 has a simple structure with a small number of parts because no support member is interposed between the needle portion 6 and the piezoelectric element 5, and the height of the valve body 23 is small, making it inexpensive. Can be manufactured.

When a voltage Vc is applied to the piezoelectric element 5 from the flow meter 9 via the lead wire 18, the flow control valve 20 expands and contracts in proportion to the magnitude of the voltage Vc, displacing the needle portion 6 in the directions of arrows A and B. Control the flow rate.

The needle portion 6 is integrally displaced with the displacement of the piezoelectric element 5, and when the needle portion 6 is at maximum displacement, the conical portion 6a is brought into contact with the valve seat 23a to close the valve.

Effects of the Invention As described above, the flow rate control valve of the present invention includes a needle portion that is provided opposite to the valve seat and controls the flow rate of fluid flowing between the needle portion and the valve seat by displacement of the needle portion, and a needle portion that is provided opposite to the valve seat and controls the flow rate of fluid flowing between the needle portion and the valve seat by applying a voltage. It consists of a piezoelectric element that moves the valve to a different position relative to the valve seat.
As in the past, when the nichrome wire is heated and the needle section is displaced due to thermal expansion, there is no IC time loss, and the piezoelectric element immediately expands and contracts in response to the control signal from the flowmeter, opening or closing the needle section. The flow rate can be controlled by displacing the valve in the closing direction, and since there is almost no time delay, the flow rate can be controlled accurately with good responsiveness.It is especially suitable for accurately controlling minute flow rates, and it is also suitable for controlling minute flow rates, and it is also suitable for controlling the heat generated by nichrome wire etc. It has the advantage that there is no thermal effect on the physical properties of the fluid because it does not use a body.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of a first embodiment of the flow control valve according to the present invention, FIG. 2 is a schematic configuration diagram of a thermal mass flowmeter, and FIG. 3 is a longitudinal sectional view of a second embodiment of the flow control valve according to the present invention. FIG. 1.20...flow control valve, 2,23a...valve seat, 3
23... Valve body, 5... Piezoelectric element, 6... Needle part, 7... Support member, 8... Diaphragm, 9...
...Thermal mass flowmeter, 11...Diversion piping, 12.13
...Detection coil, 15...Bridge circuit, 17...
- Comparison control circuit, 18... Lead wire, 22... Seal material.

Claims (1)

[Claims] 1. A needle portion that is provided opposite to the valve seat and controls the flow rate of fluid flowing between the needle portion and the valve seat by displacement thereof, and a needle portion that is displaceable with respect to the valve seat by applying a voltage. A flow control valve consisting of a piezoelectric element. 2. The flow control valve according to claim 1, wherein the piezoelectric element is separated from the fluid passage by a diaphragm and configured to displace the needle portion via a needle support member. 3. The flow control valve according to claim 1, wherein the piezoelectric element is fixed to the needle portion.