Preloaded piezo actuator and gas valve employing the actuator

Abstract

To provide a piezoelectric-based actuator which enables accurate control of a gas flow, while enabling operation in an elevated temperature, protects a piezoelectric element and resists damage caused by ambient moisture.SOLUTION: An actuator 100 comprises: a tubular housing 115; a plunger 125 arranged inside the housing and having an actuating extension 129 extending outside of the housing and coupled to a diaphragm, and configured to be slidable inside the housing; a piezoelectric body 105 arranged inside the plunger; and a pre-loader 135 applying force to the plunger so as to press the plunger against the piezoelectric body.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] [Cross reference] This application claims the benefit of U.S. Provisional Application No. 16 / 510,671, filed July 12, 2019. No. 6,399,433, the disclosure of which is incorporated herein by reference in its entirety. [Background technology]

[0002] [background] 1. Field The present disclosure relates to a piezoelectric actuator that transmits the expansion of a piezoelectric element while protecting the element from the environment. The present disclosure also relates to valves for controlling gas flow, particularly piezoelectric actuators and structures. This relates to a valve that uses a actuator. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Pat. No. 7,859,169 [Patent Document 2] U.S. Pat. No. 5,881,767 [Patent Document 3] US Patent Application Publication No. 2018 / 0163886 Summary of the Invention [Problem to be solved by the invention]

[0004] 2. Related technologies and issues to be resolved Actuators that use the expansion of a piezoelectric element due to the application of an electrical potential are known in the art. A configuration for applying a preload to a piezoelectric element is disclosed in, for example, U.S. Pat. No. 7,859,169. However, in this and other publications, a piezoelectric element is provided with a protective layer to protect the piezoelectric element from the environment. has not been addressed.

[0005] Therefore, there is a need for a piezoelectric element configuration that provides preload and protection to the piezoelectric element. For example, a structure that can operate at high temperatures up to 200°C and be protected from ambient moisture is required. It is said that.

[0006] Gas flow can be controlled using valves. If required, the flow rate can be controlled using a piezoelectric element as the driver. Very precise control of very small gas flows is required, for example, in semiconductor manufacturing facilities. do.

[0007] Gas flow valves using piezoelectric elements are disclosed, for example, in U.S. Pat. No. 5,881,767 and and U.S. Patent Application Publication No. 2018 / 0163886. These valves Although it can function properly in some environments, it is necessary to take measures to properly preload the piezoelectric element. There is also no disclosure of measures to protect the piezoelectric element so that it can operate in high temperature and high humidity environments. .

[0008] Therefore, gas flow can be precisely controlled and the device can operate at high temperatures while protecting the piezoelectric element. There is a need for piezoelectric-based actuators that are less susceptible to damage from ambient moisture. [Means for solving the problem]

[0009] The following summary of the invention is provided in order to provide a basic understanding of some aspects and features of the present invention. This Summary is not an extensive overview of the invention, and as such is not intended to provide a comprehensive understanding of the invention. It is not intended to identify essential or critical elements or to delineate the scope of the invention. Its sole purpose is to present some of the ideas of the present invention in a simplified form as set forth below. It is intended as a prelude to the detailed description.

[0010] A configuration is provided for a piezoelectric actuator that provides preload and protection for the piezoelectric element. The piezoelectric element is enclosed in a housing that protects it, while the outside of the housing In a particular embodiment, the housing is adapted to transmit a drive force due to a movement of the housing. The ring is made of a material that minimizes thermal expansion to maintain a constant preload. In an embodiment, the casing is manufactured by Carpenter, Inc. of Philadelphia, Pennsylvania. Invar 36 (INVar 36) is available from Technology Corporation. Nickel-iron alloys, also known as INVAR (registered trademark) In another embodiment, the housing is made of Carpenter Tec Nickel carbide, such as Kovar, available from Chromology Corporation In yet another embodiment, the housing is made from a tungsten alloy. The fluoropolymer is manufactured by Inovco and commercially available from Nordt EPM of Stockholm.

[0011] In some embodiments, the preload is achieved using one or more spring washers, such as disc springs. The spring washer is stacked between the housing and the piezoelectric element to provide a preload to the piezoelectric element. In some embodiments, the piezoelectric elements are stacked in series. The elements are stacked in series.

[0012] According to an aspect of the disclosure, an actuator is configured to receive a cap. an elongated tubular housing having a first end with a drive opening and a second end with a first A cap configured to be firmly attached to the end portion and a housing located within the housing. a drive end configured to slide within the drive shaft and including a shoulder and a drive extension; a drive extension sized to fit through the drive aperture; a plunger sized to extend out of the housing; and a plunger disposed within the plunger. At least one piezoelectric element abutting the inner wall of the driving end, and a piezoelectric element attached to the at least one piezoelectric element. a conductor wire attached to the housing and a small amount of material disposed within the housing and compressed between the second end and the shoulder; and at least one preload element.

[0013] According to another aspect, there is provided a valve arrangement for controlling gas flow, the valve arrangement comprising: A gas inlet, a gas outlet, and a gas cavity fluidly connecting the gas inlet to the gas outlet. and a gas block configured to control gas flow between the gas inlet and the gas outlet. and a diaphragm configured to vary the position of the diaphragm to control the gas flow. 1. An actuator comprising: a tubular housing; a drive extension disposed within the housing and extending outwardly of the housing and coupled to the diaphragm; A plunger configured to be slidable within the housing and a A force is applied to the plunger so as to press the plunger against the piezoelectric body. A valve arrangement is provided that includes an actuator and a preloader.

[0014] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present invention. The illustrated embodiments and, together with the description, serve to explain and illustrate the principles of the invention. The drawings are intended to illustrate major features of exemplary embodiments in a diagrammatic manner. The diagram is not intended to illustrate all features of an actual embodiment or the relative dimensions of the elements shown. Rather, it is not drawn to scale.

[0015] One or more embodiments of the present invention are illustrated by way of example and by way of limitation in the figures of the accompanying drawings, in which: In the accompanying drawings, like reference numbers indicate similar elements. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a cross-section of an embodiment of a drive device according to an embodiment. [Diagram 2] FIG. 2 is a cross-section of an embodiment of a drive arrangement according to another embodiment. [Diagram 3] FIG. 3 is a cross-sectional view illustrating a gas valve incorporating the actuator of FIG. 1 or FIG. [Figure 4] FIG. 4 is a cross-sectional view illustrating another gas valve incorporating the actuator of FIG. 1 or FIG. [Diagram 5] FIG. 5 is a cross section illustrating one embodiment that utilizes a bellows to seal the piezoelectric element from the surrounding environment. [Figure 6] FIG. 6 is a cross section illustrating another embodiment utilizing a bellows to seal the piezoelectric element from the surrounding environment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] An embodiment of the actuator of the present invention will be described with reference to the drawings. These combinations can be used for different applications or to obtain different advantages. The various features disclosed in the specification may be used to balance the advantages with the requirements and constraints depending on the results to be obtained. , some or all of which may be used alone or in combination with other features. Thus, although certain advantages are emphasized with respect to various embodiments, they are not limited to the disclosed embodiments. That is, the features disclosed herein are not limited to the embodiment in which they are described. The present invention is not limited to the above and may be "mixed and matched" with other features and incorporated into other embodiments. can be done.

[0018] The following embodiment describes an actuator that utilizes a preloaded, environmentally protected piezoelectric element. A non-limiting example of a piezoelectric element that can be used is the German MU11112. Available from EPCOS, Vienna, model numbers AN0X / 8516 and B58004M4 These piezoelectric devices are relatively stable at high temperatures. It can be operated steadily, but it is recommended to apply a preload of more than 100N, preferably 730N. Of course, other piezoelectric elements may be used. Suitable piezoelectric elements are This is also disclosed in Japanese Patent No. 9,425,378.

[0019] FIG. 1 illustrates a cross-section of an actuator 100. A generally tubular housing 1 15 has a drive opening 117 at one end and a cap opening 119 at the opposite end. The cap opening 119 may span the interior of the tubular housing. However, drive opening 117 has a smaller diameter and thus defines stop 118. The cap 120 is fixed to the tubular housing by, for example, screws. The cap is also secured by a set screw 121. The cap allows the lead wire 110 to pass through. 122.

[0020] A plunger 125 is disposed within the tubular housing 115. The plunger 125 The inner wall of the tubular housing 115 is spaced apart from the inner wall of the tubular housing 115 so that the inner wall of the tubular housing 115 can move freely within the tubular housing 115. The plunger 125 is also generally tubular having an internal cavity 127. The plunger 125 also fits within the drive opening 117 of the tubular housing 115. The drive extension 129 is configured to mate with and extend out of the housing 115. The portion 129 has a smaller diameter than the body of the plunger 125 , thereby creating a shoulder 130 .

[0021] A preloader 135 is disposed between the shoulder 130 and the stop 118, i.e., the tubular housing. 115. In some embodiments, the preloader is a spring washer. In some embodiments, the preloaders are stacked together in series. The preloader is connected to the drive end of the housing and to the plunger. The data is compressed between the

[0022] A piezoelectric element 105 is disposed in the cavity of the plunger. A cap 120 is attached to the tubular body 11. 5, the stopper 140 is pressed against the piezoelectric element 105 so that the stopper The stopper 140 is compressed between the plunger 125 and the piezoelectric element. The topper 140 includes a recess 142 configured to provide a gap 144 between the recess 142 and the topper 140. The topper 140 is not pressed against the plunger 125. The plunger slides freely into the gap 144. On the other hand, the preloader As the plunger 125 is pressed against the piezoelectric element 105, the plunger 125 transfers a load to the piezoelectric element 105, Thus, a preload is applied to the piezoelectric element.

[0023] The conductor 110 supplies a voltage potential to drive the piezoelectric element 105. The voltage range is, for example, For example, the voltage can be from 10 V to 180 V. When the piezoelectric element 105 is controlled to change length, the force acting on the plunger 125 is reduced. The pressure changes inversely to the force exerted by the preloader, thereby causing the plunger 1 25 slides within the tubular housing 115. As a result, the drive extension 129 The extent to which the actuator extends beyond the drive aperture 117 varies. As will be described in further detail below, devices such as gas valves can be driven.

[0024] The piezoelectric element is disposed within the plunger, which itself is positioned within the tubular housing. It should be understood that the placement of the piezoelectric element provides protection from the environment. The upper 140 insulates the interior of the tubular housing from the surrounding environment, thus protecting the piezoelectric element from moisture. It can be manufactured to protect the element. Furthermore, it is possible to provide a piezoelectric part in the plunger. By this, the piezoelectric part is made of ceramic, which is generally susceptible to chipping. This provides protection from chipping.

[0025] In certain embodiments, if the actuator is to be used at high temperatures, the housing and / or Or the plunger is made from a material that minimizes thermal expansion to maintain a constant preload. In such an embodiment, the housing and / or plunger may be Carpenter Technology Corporation, Philadelphia, PA Invar (INVAR; registered trademark), such as Invar 36 (INVAR; registered trademark), available from Ion The alloy may be made of nickel and iron, also known as VAR (registered trademark). The housing and / or plunger are manufactured by Carpenter Technology Nickel and cobalt alloys, such as Kovar, available from the Corporation. In yet another embodiment, the housing and / or plunger are made of ballast gold. Made from Inovco, commercially available from Nordt EPM, Roanoke, Alberta will be done.

[0026] Another embodiment of the actuator is shown in FIG. In this example, two piezoelectric elements 105a and 105b are inserted in series into the plunger 125. 1, except that individual conductors are connected to the piezoelectric elements 105a and 105b. When b is provided on each of the piezoelectric elements, the expansion of each piezoelectric element can be controlled separately or simultaneously. can be done.

[0027] FIG. 2 also illustrates a variation of stopper 140, which may be any of the other embodiments. In particular, in this figure, the diameter of the stopper 140 is 1 mm larger than that of the plunger 1 25. As a result, the gap 143 is formed between the plunger 125 and the cap 120. A gap is created between the plunger 125 and the housing 115 to allow the plunger 125 to slide within the housing 115. This configuration allows the assembly to be centered once preload is applied and the cap is secured in place. It helps to

[0028] FIG. 3 illustrates one embodiment in which the actuator of FIG. 2 is used to control gas flow. The lock 150 has a gas flow cavity 155, a gas inlet 102, and a gas outlet 103. The seat 107 is provided at the gas inlet entrance to the cavity 155. 09 is configured to seal against seat 107 when engaged with seat 107. The fram 109 is attached to a rod 108 which is in turn attached to a drive extension 129 As a result, when the piezoelectric element expands or contracts due to an applied potential, the actuated extension The portion 129 acts on the rod 108, which in turn draws the fluid from the inlet portion 102 into the cavity 155, thus The diaphragm is moved in the direction of the double arrow so as to control the gas flow rate to the gas outlet 103. Move.

[0029] The embodiment of FIG. 3 illustrates a diaphragm sealing the gas inlet. However, The diaphragm seals the gas outlet or both the gas inlet and gas outlet. It can be configured.

[0030] FIG. 4 illustrates the actuator of FIG. 1 in accordance with U.S. Patent Application Publication No. 2018 / 0163886. 1 illustrates another embodiment for use in a gas valve as disclosed herein. The valve 300 includes an actuator frame 302, a bending element 304, and a mechanical amplifier. 306, a piezoelectric actuator 308 according to any of the above-mentioned embodiments, and a rigid clamp. The spring 310, the bidirectional flexure 312, the diaphragm housing 314, and the preload spring 31 6 and a valve block 318.

[0031] The diaphragm housing 314 is attached to a valve block 318. The eta frame 302 is attached to the outer portion of the diaphragm housing 314. The bottom of the mechanical amplifier 306 is mechanically connected to the diaphragm 319 via a bidirectional flexure 312. The bidirectional bend 312 can be bent or curved in any direction. The diaphragm 319 is held against the orifice of the gas inlet 320 by a spring 316. The spring 316 presses against the preload spring clamp 3, thereby blocking the flow of gas. It is held in place by 15.

[0032] The piezoelectric actuator 308 is disposed within the mechanical amplifier 306. In the illustrated embodiment, the piezoelectric actuator 308 is in a relaxed state, i.e. As shown, in one embodiment, the mechanical amplifier 3 06 provides a stroke multiplier that amplifies the movement of the piezoelectric actuator 308. For example, in one embodiment, mechanical amplifiers 306, when the piezoelectric actuator 308 expands, the expansion of the piezoelectric actuator 30 The actuator is designed to be extended in a direction perpendicular to the direction of expansion of the piezoelectric actuator. By applying a positive voltage to 308, the mechanical amplifier 306 retracts and the upper mounting Due to the rigidity of the fixture, the diaphragm 319 is forced against the inlet orifice of the valve block 318. This allows for control of the gas flow from the inlet 320 to the outlet 322. do.

[0033] FIG. 5 shows a particularly strong protection for the piezoelectric element, especially from moisture and gaseous chemicals. Where protection is desired, suitable embodiments of the gas valves disclosed herein include 13 illustrates another embodiment. As mentioned above, placing a piezoelectric element within the plunger In addition, the housing is made of materials with little or no thermal expansion. and / or the construction of the plunger provides stability for operation at high temperatures. The cap 120 and the stopper 140 isolate the piezoelectric element from the environment. In this embodiment, the piezoelectric element couples the bellows 160 to one end of the plunger 125 and the stopper. 140 and the other end of the housing 115 to isolate the system from the outside environment. In the embodiment of FIG. 5, recess 142 is provided to attach the bellows to stopper 140. A similar recess 123 is provided in the plunger 125, and the bellows The piezoelectric element 105 is attached at the recess 123. In this manner, the entire piezoelectric element 105 is protected. At this time, the inner cavity 127 is filled with an inert gas such as argon to form an annulus around the piezoelectric element. You can control the entire boundary.

[0034] In any of the embodiments of FIG. 5 and the other embodiments, a hermetic seal for the conductor 110 may be provided. If it is desired to do so, the following procedure can be used: First, appropriate holes are drilled The wire 110 is then inserted into the hole, making sure not to touch the side walls of the hole. The glass frit fills the space in the hole between the sidewall of the hole and the conductive wire. The assembly of stopper 140, frit and lead wire is then placed in an oven and heated. The lid is melted to create a hermetic glass seal 111 .

[0035] FIG. 6 shows an embodiment in which a bellow seals the cap 120 rather than the stopper 140. In such an embodiment, the attachment of the cap 120 to the housing is The cap needs to be able to rotate freely to fit in, but this is achieved by the bellows. Since the screw-type mounting of the embodiment of FIG. 1 is not required, it is possible to use a different mounting method. So, to seal the cap with a bellows, it needs to be rotatable or Or the attachment of the cap to the housing should not require rotation. Also, in this particular example, the stopper 140 is enclosed within a bellows 160 .

[0036] The processes and techniques described herein are not inherently related to any particular apparatus. It is to be understood that the present invention may be implemented by any suitable combination of components, rather than by any particular embodiment. Moreover, the teachings described herein may be used with a variety of general purpose types of equipment. The present invention has been described in relation to particular embodiments, but these are not to be construed as limiting in any respect. Rather, they are intended to be illustrative. Various combinations may be suitable for practicing the present invention. Those skilled in the art will understand that.

[0037] Moreover, other embodiments of the present invention may be contemplated by practice of the present invention as disclosed herein and herein. Various aspects of the described embodiments and / or The components may be used alone or in any combination. The following claims are intended to indicate, by way of example only, the true spirit and scope of the invention. It is intended to be considered.

Claims

1. An actuator, the actuator comprising: a first end configured to receive a cap and a second end having a drive opening; an elongated tubular housing having a cap configured to be securely attached to the first end; a shoulder and a support member disposed within the housing and configured to slide within the housing; a plunger having a drive end including a drive extension, the drive extension having a size of a drive opening that fits into the drive opening and extends through the drive opening out of the housing; A plunger having a size of At least one piezoelectric element disposed within the plunger and abutting an inner wall of the drive end. With my child, a conductive wire attached to the at least one piezoelectric element; At least one of the first and second ends is disposed within the housing and compressed between the second end and the shoulder. and a preload element.

2. The cap is configured to secure the piezoelectric element to the first end when the cap is firmly attached to the first end. The actuator of claim 1 configured to bias an element against the preload element. 。

3. The actuator of claim 2 , wherein the preload element comprises at least one spring washer.

4. The actuator of claim 2 , wherein the preload element comprises at least one disc spring.

5. The actuator of claim 1 , wherein the cap includes a passage for the electrical lead.

6. 2. The piezoelectric element according to claim 1, wherein the piezoelectric element comprises a plurality of piezoelectric transducers stacked in series. The actuator described herein.

7. At least one of the housing and the plunger is made of Invar (registered trademark).

10. The actuator of claim 1, comprising:

8. The piezoelectric element according to claim 1 , further comprising a stopper disposed between the cap and the piezoelectric element. The actuator described herein.

9. The stopper is sized to define a gap between the stopper and the plunger. The actuator of claim 8 including a recess.

10. The at least one piezoelectric element includes a plurality of piezoelectric elements stacked in series, The conductive wire includes a plurality of lead wires individually attached to each of the plurality of piezoelectric elements. The actuator according to claim 1.

11. A bellows is further provided to seal one end of the plunger and the other end of the cap. The actuator of claim 1 .

12. A bellows attached to one end of the plunger and the other end of the stopper. The actuator of claim 8 further comprising:

13. The plunger further contains an inert gas and is sealed with the bellows.

13. An actuator as described in claim 12.

14. 1. A valve arrangement for controlling gas flow, the valve arrangement comprising: a gas inlet, a gas outlet, and a gas space fluidly connecting the gas inlet to the gas outlet. a gas block having a cavity; A diaphragm configured to control gas flow between the gas inlet and the gas outlet. Ram and an actuator configured to vary the position of the diaphragm to control the gas flow; and a actuator, the actuator comprising: A tubular housing; A wire is disposed within the housing, extends outside the housing and is coupled to the diaphragm. a plunger having a drive extension and configured to be slidable within the housing; A piezoelectric body disposed within the plunger; A pressure is applied to the plunger so as to press the plunger against the piezoelectric body. a valve arrangement comprising: a loader; and an actuator comprising:

15. The preloader includes a plurality of preloaders disposed between the housing and the plunger.

15. The valve arrangement of claim 14 including a washer.

16. a cap fixedly attached to the housing; the cap and the piezoelectric element; 16. The valve arrangement of claim 15, further comprising a stopper compressed between said stopper and said valve arrangement.

17. The stopper has a recess that forms a gap between the stopper and the plunger.

17. The method of claim 16, wherein the plunger is free to slide into the gap. Valve configuration.

18. 15. The valve of claim 14, wherein the piezoelectric body comprises a plurality of piezoelectric elements stacked in series. composition.

19. The piezoelectric element of claim 1 further comprising a plurality of electrical leads individually coupled to each of the stacked piezoelectric elements.

19. The valve arrangement according to claim 18.

20. 15. The valve arrangement of claim 14, further comprising a mechanical amplifier.

21. At least one of the housing and the plunger is made of Invar (registered trademark).

15. The valve arrangement of claim 14, comprising:

22. 15. The piezoelectric device of claim 14, further comprising a bellows for sealing the piezoelectric element from the surrounding environment. Configuration.

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