JP2013100851A - Flow regulating valve - Google Patents

Abstract

A relative position change between a flow valve and an actuator due to a temperature change can be effectively absorbed without increasing the size of the apparatus.
A base, a flow rate valve fixed to the base, an actuator, and a flow rate adjustment valve in which the base and the actuator are connected via a thermal displacement member. Further, an insulator means is further provided between the thermal displacement member and the base or actuator for transmitting the displacement of the thermal displacement member in a direction that cancels the change in the relative position between the flow valve and the actuator caused by the temperature change.
[Selection] Figure 1

Description

  The present invention relates to a flow rate adjusting valve driven by a piezoelectric or magnetostrictive actuator. Such a flow valve adjustment can be used to supply a gas at a predetermined flow rate, such as a flow controller that supplies a carrier gas at a constant flow rate in a gas chromatograph.

A flow control valve using a piezoelectric or magnetostrictive actuator has a function of opening and closing the valve by inputting displacement into the flow valve by a piezoelectric element or a magnetostrictive element (hereinafter referred to as “driving element”) of the actuator. Have. In a conventional flow rate adjusting valve, an actuator is also fixed to a base to which the flow rate valve is fixed.
In the flow rate adjusting valve in which the actuator is also fixed to the base, the relative position between the flow rate valve and the actuator changes due to a temperature change. In order to absorb the change in the relative position, a method is known in which a thermal displacement adjusting member having a predetermined thermal expansion coefficient is interposed (see Patent Document 1).

JP 60-129481 A

  However, the displacement amount may be insufficient simply by interposing the thermal displacement adjusting member. If the thermal displacement adjusting member is enlarged in order to absorb a large amount of displacement, the apparatus becomes larger and the weight increases accordingly.

  In view of such a situation, the present invention provides a flow adjustment valve that utilizes displacement of a piezoelectric or magnetostrictive actuator, and does not increase the size of the device, and changes the relative position between the flow valve and the actuator due to temperature changes. It aims to be able to absorb effectively.

  In the flow regulating valve of the present invention, the flow valve is fixed to the base, but the actuator that drives the flow valve is not fixed directly to the base, but is fixed to the base via the thermal displacement member and the lever means. .

  That is, the flow rate adjusting valve of the present invention is a flow rate adjusting valve in which a base, a flow rate valve fixed to the base, an actuator, and the base and the actuator are connected via a thermal displacement member. Further, an insulator means is further provided between the thermal displacement member and the base or actuator for transmitting the displacement of the thermal displacement member in a direction that cancels the change in the relative position between the flow valve and the actuator caused by the temperature change.

  In a preferred embodiment, the thermal displacement member is composed of a plurality of members having different thermal expansion coefficients, and the displacement of the thermal displacement member is configured to be a difference in displacement due to the difference in thermal expansion coefficients of the plurality of thermal displacement members. Yes.

  As an example, the thermal displacement member includes a first support column and a second support column, and both the support columns are set to have the same length at 25 ° C., and both are made of a material having a positive thermal expansion coefficient. More specifically, the material of the first support column is a stainless alloy, and the material of the second support column is an aluminum alloy.

  According to the present invention, since the relative position change between the flow valve and the actuator due to temperature change is canceled by the lever means, it is possible to avoid increasing the size of the apparatus.

It is sectional drawing which shows one Example. It is sectional drawing which shows the flow valve in the Example.

  FIG. 1 shows a flow rate adjusting valve of one embodiment. Although the use of this flow control valve is not particularly limited, it can be used, for example, as a flow control valve for supplying a carrier gas to an analysis channel in a gas chromatograph.

  The flow valve 1 is a diaphragm valve, for example, and is fixed to the base 2. As will be described later with reference to FIG. 2, the diaphragm valve 1 is opened when the ruby ball 3 is pressed, and is closed when the push-down of the ruby ball 3 is released.

  The base 2 is provided with flow paths 2a and 2b. The channel 2a is an upstream channel, for example, a channel through which a carrier gas is sent. The channel 2b is a downstream channel, for example, a channel that supplies a carrier gas to the analysis channel of the gas chromatograph. Intermittent and flow rates between the flow paths 2a and 2b are controlled by the diaphragm valve 1. In this example, the flow paths 2 a and 2 b are formed integrally with the base 2, but the flow paths 2 a and 2 b may be formed of parts different from the base 2.

  An actuator 4 is disposed above the ruby ball 3 in order to push down the ruby ball 3 and release the ruby ball 3. The actuator 4 houses a piezoelectric or magnetostrictive drive element 5 that expands and contracts when a voltage is applied in a case 8, and the fixed end 5 A of the drive element 5 is positioned on the base end side of the case 8 by a spacer 9 and a cap 10. It is fixed inside. In the case 8, the needle 6 is also accommodated on the distal end side of the case 8. A hole is provided at the tip of the case 8, and the tip of the needle 6 protrudes from the hole at the tip of the case 8 and is slidable with respect to the hole. The needle 6 has a hook at the base end, and a coil spring 7 is inserted in a compressed state between the hook of the needle 6 and the inner surface of the tip of the case 8, and the base end face of the needle 6 is driven by the coil spring 7. It is pressed so as to always contact the output end 5B of the element 5. Thereby, the drive element 5 expands and contracts by applying a voltage to the drive element 5, and the position of the tip of the needle 6 protruding from the case 8 is displaced.

  The case 8 is fixed to the holding beam 12 by a set screw 11 at a position on the base end side, and the holding beam 12 is fixed to the base 2 via the first support column 13 and the second support column 14. Yes.

  A lever means for displacing the actuator 4 is constituted by the holding beam 12, the first support column 13 and the second support column 14. The first support column 13 and the second support column 14 are specific examples of thermal displacement members.

  A support position 13 </ b> A where the support column 13 supports the holding beam 12 on one end side thereof is a position away from the center of the actuator 4 by a predetermined distance A. The support position 14A where the support column 14 supports the holding beam 12 at one end side thereof is a position further away from the center of the actuator 4 by a predetermined distance B than the support position 13A, that is, a distance (A + B from the center of the actuator 4). ). The support columns 13 and 14 are made of materials having different thermal expansion coefficients. The height from the respective support positions 13A, 14A to the base 2 at the ambient temperature (reference temperature) during normal operation of the apparatus using the flow rate adjusting valve is a reference. In this embodiment, the height L from the support positions 13A, 14A to the base 2 is set to be equal at the reference temperature. However, the height from the support positions 13A, 14A to the base 2 does not necessarily have to be equal under the reference temperature. However, the support positions 13A and 14A must be at the same height. (This is because if the heights of the support positions 13A and 14A are different, the holding beam is inclined, so that it is necessary to newly consider the thermal expansion of the holding beam.) The actuator 4 has the holding beam 12 and the support columns 13 and 14 as well. Only the tip of the needle 6 faces the flow valve 1 side, and the tip of the needle 6 is positioned at a position where the ruby ball 3 of the flow valve 1 can be pushed under the reference temperature. A member for directly fixing the tip of the actuator 4 to the base 2 is not provided.

  The holding beam 12 is coupled to the support columns 13 and 14 so as to be freely rotatable without play by pins at the support positions 13A and 14A. However, this coupling may be fixed using bolts or the like so as not to be freely rotatable.

  When the environmental temperature when the flow rate adjusting valve is operated changes from the reference temperature, the protruding amount of the tip position of the needle 6 changes with respect to the tip position of the case 8, and the support columns 13 and 14 have a coefficient of thermal expansion relative to each other. Different lengths result in different lengths. At this time, according to the principle of the lever by the holding beam 12 having the support position 13A as a fulcrum, the support position 14A as a force point, and the point where the holding beam 12 is fixed to the case 8, the needle 6 is changed by the environmental temperature change. The length L of each of the support positions 13A, 14A and the support columns 13, 14 from the support positions 13A, 14A to the base 2 and the support column 13 so as to displace the case 8 in a direction that cancels out the change in the protrusion amount at the tip position , 14 are set.

  Here, a diaphragm valve 1 as an example of a flow valve is shown in FIG. A valve body 20 having a diaphragm for continuity between the flow paths 2a and 2b and flow control is detachably provided to the valve seat 22. The valve body 20 is suspended from another diaphragm 26 by a support rod 24, and the valve body 20 is in close contact with the valve seat 22 and is urged in a direction to close the valve. A ruby ball 3 is disposed on the diaphragm 26 as a push ball. When the ruby ball 3 is pushed down by the tip of the needle 6, the valve body 20 is separated from the valve seat 22 and the valve is opened.

  In the present embodiment, the displacement of the ruby ball 3 necessary for opening and closing the diaphragm valve 1 is 5 μm. The driving element 5 is a piezoelectric element that can obtain a displacement of 12 μm by applying a voltage of 100 V at the maximum. Therefore, the position in the height direction of the actuator 4 is adjusted so that the gap between the needle tip 6A and the ruby ball 3 is in the range of 0 μm or more and 7.0 μm or less with the drive element 5 in a non-energized state. It is fixed. Thereby, the flow rate can be adjusted by driving the diaphragm valve 1 by applying a voltage to the actuator 4.

  Next, the operation when the temperature of the entire structure changes from the reference state due to the environmental temperature change will be described. However, it is assumed that the thermal expansion of the structural material is proportional to the temperature change. This premise is a reasonable precondition if the temperature range in which the flow valve is used is about room temperature ± 25 ° C.

In this embodiment, the drive element 5 has a linear expansion coefficient of −3.0 × 10 ⁻⁶ / ° C. and a length of 20 mm. The needle 6, the case 8, the spacer 9, the cap 10, the holding beam 12, and the support column 13 are made of a stainless alloy having a linear expansion coefficient of 10.5 × 10 ⁻⁶ / ° C. The length of the needle 6 is 7 mm, the length of the support columns 13 and 14 (the length L from the support positions 13A, 14A to the base 2) is 21 mm, and the height from the upper surface of the base 2 to the piezoelectric element fixing end 5A The dimension is 30 mm.

The reference temperature is 25 ° C. For example, if the environmental temperature is 50 ° C., the thermal expansion of the needle 6 is 10.5 × 10 ⁻⁶ × 7 × (50−25) = 1.8 μm, and the thermal expansion of the driving element 5 is −3.0 × 10. ⁻⁶ × 20 × (50−25) = − 1.5 μm. Therefore, the dimension between the driving element fixed end 5A and the needle tip 6A expands by 1.8−1.5 = 0.3 μm.

Here, if the same stainless steel alloy as that of the support column 13 is used as the material of the support column 14, the height dimension from the upper surface of the base 2 to the piezoelectric element fixed end 5A is 10.5 × 10 ⁻⁶ × 30 × (50− 25) = Expands 7.9 μm.

  The thermal expansion of the diaphragm valve 1 and the ruby sphere 3 is negligible because of its small size and thermal expansion coefficient.

  As a result, when the environmental temperature is 50 ° C., the gap between the needle tip 6A and the ruby ball 3 is increased by 7.9−0.3 = 7.6 μm. Therefore, even if the gap is adjusted to be in the range of 0 μm to 7.0 μm at 25 ° C., the gap becomes larger than 7.0 μm when adjusted to the maximum value at 50 ° C. The valve 1 cannot be driven normally.

Therefore, in one embodiment, the support column 14 is formed of a material having a larger linear expansion coefficient than the support column 13. Furthermore, the dimensions of the flow valve drive structure are designed to satisfy the following formula 1.
Δx = (A / B) (α ₁₄ −α ₁₃ ) LΔT (Formula 1)
Here, each variable is as follows.
Δx: A change amount of the gap between the needle tip 6A and the ruby ball 3 to be offset.
A: Distance between the centers of the actuator 4 and the column 13.
B: and the distance between the centers of the columns 13 and 14.
α ₁₃ : Linear expansion coefficient of the column 13.
α ₁₄ : Linear expansion coefficient of the column 14.
L: The length of the pillar 13 and the pillar 14.
Δ: Temperature change of the structure.

When the temperature of the entire structure changes by ΔT from the reference temperature due to a change in environmental temperature, the support column 14 becomes longer than the support column 13 by (α ₁₄ −α ₁₃ ) LΔT. Then, the holding beam 12 is inclined with respect to the base 2 by the lever principle, and the actuator 4 is displaced downward relative to the support column 13 by (A / B) (α ₁₄ −α ₁₃ ) LΔT (arrow 12A). ). According to Equation 1, the downward displacement amount (A / B) (α ₁₄ −α ₁₃ ) LΔT is equal to the gap change amount Δx to be offset. Therefore, the tip 6A of the actuator 4 is not displaced in the vertical direction due to the temperature, and the influence of thermal expansion is offset.

Furthermore, since the change amount Δx of the gap is caused by linear thermal expansion of the structural material, Δx is proportional to ΔT. Similarly, the downward displacement (A / B) (α ₁₄ −α ₁₃ ) LΔT of the actuator 4 is also proportional to ΔT. That is, according to the present invention, the influence of thermal expansion can be offset at an arbitrary temperature change ΔT. It is clear that it is effective not only when the temperature of the structure increases but also when it decreases.

In the present embodiment, a stainless alloy is used for the support column 13 and an aluminum alloy is used for the support column 14. The linear expansion coefficient of each material is α ₁₃ = 10.5 × 10 ⁻⁶ / ° C. and α ₁₄ = 23.4 × 10 ⁻⁶ / ° C. Further, from the above, Δx = 7.6 μm, L = 21 mm, ΔT = 50−25 = 25 ° C.

Here, in order to satisfy Formula 1, for example, A = 10 mm and B = 9 mm are designed. Then, the right side of Equation 1 is (10/9) × (23.4 × 10 ⁻⁶ −10.5 × 10 ⁻⁶ ) × 21 × 25 = 7.5 μm, and the gap variation Δx = 7.6 is almost satisfied. Equal amounts can be offset. In this way, a drive mechanism for the flow valve that is not affected by thermal expansion can be realized.

DESCRIPTION OF SYMBOLS 1 Diaphragm valve 2 Base 2a Flow path 3 Ruby ball 4 Piezoelectric or magnetostrictive actuator 5 Piezoelectric or magnetostrictive element 5A Element fixed end 5B Element output end 6 Needle 6A Needle tip 7 Spring 8 Case 9 Spacer 10 Cap 11 Set screw 12 Holding beam 13, 14 Pillars 13A, 14A Rotation support center 15 Holding base

Claims (4)

Base and
A flow valve fixed to the base;
An actuator,
The base and the actuator are flow rate adjustment valves connected via a thermal displacement member,
Further, lever means for transmitting the displacement of the thermal displacement member between the thermal displacement member and the base or the actuator in a direction to cancel the change in the relative position between the flow valve and the actuator caused by a temperature change. A flow regulating valve characterized by comprising: The thermal displacement member is composed of a plurality of members having different coefficients of thermal expansion,
2. The flow rate adjustment valve according to claim 1, wherein the displacement of the thermal displacement member is configured to be a difference in displacement due to a difference in coefficient of thermal expansion between the plurality of thermal displacement members.   3. The thermal displacement member includes a first support column and a second support column, and both the support columns are set to be equal in length at 25 ° C. and both are made of a material having a positive thermal expansion coefficient. The flow regulating valve described in 1.   The flow regulating valve according to claim 3, wherein the material of the first support column is a stainless alloy, and the material of the second support column is an aluminum alloy.

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