Electrostatically actuated valve

The present invention generally relates to electro-pneumatic transducers, and more particularly, to electrostatically actuated valves.

Many industrial, commercial, aerospace, military and other applications depend critically on reliable valves for fluid (including gas) handling. In a chemical plant, for example, valves are often used to control the flow of fluid throughout the facility. Likewise, in an airplane, valves are often used to control air and fuel delivery, as well as some of the hydraulic systems that drive the control surfaces of the airplane. These are just a few examples of the many applications that depend critically on reliable valves for fluid (including gas) handling.

In many cases, one or more main valves are used to directly control the fluid. In other cases, smaller control or pilot valves are used to control the operation of a main valve. In any eases, it is often desirable to minimize the power and/or voltage required to operate the main and/or pilot valves, particular in wireless applications but also in other applications. While some prior art valves perform satisfactory for some applications, many have significant shortcomings including a relatively large size and weight, a relatively large voltage and/or power requirement, a relatively high fabrication cost, and/or other shortcomings. Examples of prior art devices can be found described in WO97/29538, US-B1-6179586, US-A-6106245, US-B1-6184607 and US-A-4498850.

The present invention provides an electrostatic actuated valve, the valve including: <ul id="ul0001" list-style="none" compact="compact"><li>a body forming a chamber, the chamber having a first port and a second port;</li><li>a diaphragm mounted in the chamber, the diaphragm having a first position that restricts fluid from flowing between the first port) and the second port and a second position that allows fluid to flow between the first port and the second port; and</li><li>a first electrode secured relative to the diaphragm and a second electrode secured relative to the body,</li></ul> wherein: <ul id="ul0002" list-style="none" compact="compact"><li>the diaphragm is electrostatically actuated from the first position to the second position and/or from the second position to the first position when a voltage is applied between the first electrode and the second electrode;</li><li>the chamber has a first opposing wall and a second opposing wall;</li><li>the diaphragm is mounted between the first opposing wall and the second opposing wall; and</li><li>the first port extends through the first opposing wall and into the chamber,</li></ul> characterised in that: <ul id="ul0003" list-style="none" compact="compact"><li>the diaphragm is arranged such that, in use, it at least substantially returns to the first position under an elastic restoring force when not electrostatically actuated; and</li><li>the diaphragm is configured to cover the first port when in its first position.</li></ul>

According to a preferred feature of the invention, the first opposing wall and the second opposing wall are configured such that the spacing between the first opposing wall and the second opposing wall is smaller in a first region of the chamber than in an adjacent second region, and the mounting of the diaphragm is such that the diaphragm is electrostatically pulled toward the second electrode in a rolling action beginning in the first region.

According to a preferred feature of the invention, the second port extends through the second opposing wall and into the chamber, the diaphragm is arranged to be adjacent the first opposing wall when in its first position and has at least one opening that is laterally offset from the first port in the first opposing wall when the diaphragm is in its first position, and the second electrode is secured relative to the second opposing wall, such that the diaphragm is electrostatically pulled toward the second opposing wall when a voltage is applied between the first electrode and the second electrode, thereby allowing fluid to flow between the first port and the second port via the at least one opening.

According to a preferred feature of the invention, the second port extends through the first opposing wall and into the chamber, the diaphragm is arranged to be adjacent the first opposing wall when in its first position, and the second electrode is secured relative to the second opposing wall, such that the diaphragm is electrostatically pulled toward the second opposing wall when a voltage is applied between the first electrode and the second electrode, thereby allowing fluid to flow between the first port and the second port. According to a further preferred feature of the invention, the valve is arranged such that a fluid passing between the first port and the second port is not substantially exposed to the electrostatic field that is produced when the valve member is electrostatically actuated. According to a further preferred feature of the invention, the first opposing wall and the second opposing wall are configured such that the spacing between the first opposing wall and the second opposing wall is smaller near the edge of the chamber than near the center of the chamber, and the mounting of the diaphragm is such that the diaphragm is electrostatically pulled toward the second electrode in a rolling action.

In the Drawings: <ul id="ul0004" list-style="none" compact="compact"><li>Figure 1 is a cross-sectional side view of an illustrative normally closed valve in accordance with the present invention;</li><li>Figure 2 is a cross-sectional top view of the illustrative normally closed valve of Figure 1;</li><li>Figure 3 is a cross-sectional side view of the illustrative normally closed valve of Figure 1 with the diaphragm partially activated;</li><li>Figure 4 is a cross-sectional side view of the illustrative normally closed valve of Figure 3 with the diaphragm further activated;</li><li>Figure 5 is a cross-sectional side view of another illustrative normally closed valve in accordance with the present invention;</li><li>Figure 6 is a cross-sectional side view of yet another illustrative normally closed valve in accordance with the present invention;</li><li>Figure 7 is a cross-sectional side view of yet another illustrative normally closed valve in accordance with the present invention;</li><li>Figure 8 is a cross-sectional top view of the illustrative normally closed valve of Figure 7;</li><li>Figure 9 is a cross-sectional side view of the illustrative normally closed valve of Figure 7 with the diaphragm at least partially activated;</li><li>Figure 10 is a cross-sectional side view of an illustrative normally open valve in accordance with the present invention;</li><li>Figure 11 is a cross-sectional side view of the illustrative normally open valve of Figure 10 with the diaphragm partially activated;</li><li>Figure 12 is a cross-sectional side view of the illustrative normally open valve of Figure 10 with the diaphragm fully activated;</li><li>Figure 13 is a cross-sectional side view of an illustrative three-way valve in accordance with the present invention;</li><li>Figure 14 is a cross-sectional side view of the illustrative three-way valve of Figure 13 with the diaphragm partially activated; and</li><li>Figure 15 is a cross-sectional side view of the illustrative three-way valve of Figure 14 with the diaphragm further activated.</li></ul>

Detailed Description

The following description should be read with reference to the drawings wherein like reference numerals indicate like elements throughout the several views. The detailed description and drawings are presented to show embodiments that are illustrative of the claimed invention.

Figure 1 is a cross-sectional side view of an illustrative normally closed valve in accordance with the present invention. The valve is generally shown at 5, and has a body 10 with a first opposing wall 14 and a second opposing wall 16 that define a valve chamber 12. In the illustrative embodiment, a first port 42 (e.g. inlet port) extends into the valve chamber 12 through the first opposing wall 14. One or more second ports (e.g. outlet ports), such as ports 44a and 44b, extend into the valve chamber 12 through the second opposing wall 16.

A diaphragm 20 is mounted within the chamber 12. In some embodiments, this may be accomplished by sandwiching the diaphragm 20 between an upper body portion 13 and a lower body portion 11. In the illustrative embodiment, the diaphragm 20 extends along the first opposing wall 14 in the un-activated state. In some embodiments, the diaphragm 20 is spaced from the first opposing wall 14 except along a valve seat 23, which extends around the first port 42. To actuate the diaphragm 20, the diaphragm 20 may include one or more electrodes, which may extend to at least near the edges of the chamber 12. In some embodiments, the one or more electrodes of the diaphragm are surrounded or encapsulated in a dielectric material or layer.

In the embodiment shown in Figure 1, the second opposing wall 16 includes one or more stationary electrodes, such as electrode 30. The second opposing wall 16 and the diaphragm 20 may be configured so that, in the un-activated state, the separation distance between the stationary electrode 30 and the electrode of the diaphragm 20 is smaller near the edges of the chamber 12. In other embodiments, however, the separation distance between the stationary electrode 30 and the electrode of the diaphragm 20 may be smaller in the center or any other area of the chamber 12, as desired. By providing a region in the chamber 12 that has a smaller separation distance, the diaphragm 20 may be drawn toward the second opposing wall 16 in a rolling action when a voltage is applied between the electrode of the diaphragm 20 and the stationary electrode and 30, as further shown in Figures 3-4. Such a rolling action may help improve the efficiency and reduce the voltage requirements of the valve.

For purposes of illustration, the first opposing wall 14 is shown generally flat. However, the first opposing wall 14 may assume other shapes, depending upon the application. For example, the first opposing wall 14 may have different regions that are recessed or protrude against the diaphragm 20 in order to, for example, reduce damage to the diaphragm 20 after continued activation. Other shapes may also be used, including curved shapes, for example. Although the second opposing wall 16 is shown to be generally curved, other shapes may be used, depending on the application.

Body 10 may be made from any suitable semi-rigid or rigid material, such as plastic, ceramic, silicon, etc. In one illustrative embodiment, the body 10 is constructed by molding a high temperature plastic such as ULTEM^™ (available from General Electric Company, Pittsfield, Mass.), CELAZOLE^™ (available from Hoechst-Celanese Corporation, Summit, N.J.), KETRON^™ (available from Polymer Corporation, Reading, Pa.), or some other suitable material. In some embodiments, the material used for the diaphragm 20 may have elastic, resilient, flexible or other elastomeric properties. In other embodiments, the diaphragm 20 is made from a generally compliant material. In one embodiment, the diaphragm 20 is made from a polymer such as KAPTON^™ (available from E. I. du Pont de Nemours &amp; Co., Wilmington, Del.), KALADEX^™ (available from ICI Films, Wilmington, Del.), MYLAR^™ (available from E. I. du Pont de Nemours &amp; Co., Wilmington, Del.), or any other suitable material. An advantage of using a polymer based substrate and/or diaphragm is that the resulting valve may be cheaper and lighter, and/or more suitable for small handheld, or even disposable or reusable applications.

The one or more electrodes on the diaphragm 20 may be provided by patterning a conductive coating on the diaphragm 20. For example, the one or more electrodes may be formed by printing, plating or EB deposition of metal. In some cases, the electrode layer may be patterned using a dry film resist. The same or similar techniques may be used to provide the electrode 30 on the second opposing wall 16 of the body 10. Rather than providing a separate electrode layer, it is contemplated that the diaphragm 20 and/or second opposing wall 16 may be made conductive so as to function as an electrode, if desired. A dielectric, such as a low temperature organic and inorganic dielectric, may be used as an insulator between the actuating electrodes. The dielectric may be coated over the electrode on the diaphragm 20, the electrode 30 on the second opposing wall 16, or both, as desired.

As shown in Figure 1, the diaphragm 20 may have at least one opening (openings 25a and 25b) that is laterally offset from the first port 42 when the diaphragm 20 is in a first position adjacent the first opposing wall 14. Figure 2 is a cross-sectional top view of the illustrative normally closed valve of Figure 1. As can be seen in Figure 2, the diaphragm 20 may include one or more openings 25a and 25b.

The openings 25a and 25b in the diaphragm 20 may be configured so that the diaphragm 20 covers or otherwise restrict fluid flow through the first port 42 and into the chamber 12 when the diaphragm 20 is adjacent the first opposing wall 14. When the diaphragm is electrostatically actuated and pulled toward the second opposing wall 16, as shown in Figures 3-4, the diaphragm may move away and uncover the first port 42. This may allow fluid to flow between the first port 42 and the second port or ports 44a and 44b via the one or more openings 25a and 25b in the diaphragm 20.

In some embodiments, the diaphragm 20 may become elastically deformed when electrostatically pulled toward the second opposing wall 16. When so provided, the diaphragm 20 may return to the un-activated first position adjacent the first opposing wall 14 under elastic restoring forces when the activation voltage is removed or reduced between the electrode of the diaphragm 20 and the electrode 30 of the second opposing wall 16. In this illustrative embodiment, the diaphragm 20 may only need to be electrostatically actuated in one direction, with the elastic restoring forces returning the diaphragm 20 to the original un-actuated state.

To increase the elastic restoring forces, the diaphragm 20 may be disposed across the chamber 12 under tension. Alternatively, or in addition, the diaphragm 20 may be made from a material with a preformed shape to which the diaphragm 20 elastically returns after application of a deforming force. In either case, the diaphragm 20 may be made from a material, form, or disposed in a fashion such that the diaphragm 20, once deformed as shown in Figures 3-4, generates a restoring force that pulls the diaphragm 20 back towards the first opposing wall 14, such as shown in Figure 1.

In some embodiments, supplemental restoring forces may be provided to help restore the diaphragm 20 to the un-activated first position adjacent the first opposing wall 14. In one embodiment, like charges may be applied to both the electrode on the diaphragm 20 and the electrode 30 on the second opposing wall 16, creating a repelling electrostatic force therebetween. This repelling electrostatic force may help push the diaphragm 20 back toward the first opposing wall 14. Alternatively, or in addition, supplemental restoring forces may be created by providing an additional or third electrode 52 along the first opposing wall 14, as shown in Figure 5. By applying a voltage between the electrode on the diaphragm 20 and the additional third electrode 52, the diaphragm 20 may be pulled back toward the first opposing wall 14, preferably in a rolling action.

In some embodiments, the diaphragm 20 may be configured to be positioned away from the first opposing wall 14 in the un-activated state. This may be accomplished by, for example, pre-shaping the diaphragm 20. When so provided, and in some embodiments, the diaphragm 20 may become elastically deformed when it is electrostatically pulled toward the first opposing wall 14. Such a force may be provided by, for example, applying like charges to the electrode of the diaphragm 20 and the electrode 30 of the second opposing wall 16, thus creating a repelling electrostatic force. Alternatively, or in addition, an electrode may be secured relative to the first opposing wall 14, wherein the diaphragm is electrostatically pulled toward the first opposing wall 14 when a voltage is applied between the electrode of the diaphragm 20 and the electrode of the first opposing wall 14.

Figure 3 is a cross-sectional side view of the illustrative normally closed valve of Figure 1 with the diaphragm partially activated. As discussed above, the chamber 12 may have a first opposing wall 14 and a second opposing wall 16, with the second electrode 30 secured relative to the second opposing wall 16. As shown in Figure 1, the first opposing wall 14 and the second opposing wall 16 may be configured such that the spacing between the first opposing wall 14 and the second opposing wall 16 is smaller in a first region of the chamber 12 than in an adjacent second region. In Figure 1, the first region is toward the edge or edges of the chamber 12 and the second region is toward the center of the chamber 12. The diaphragm 20 is mounted between the first opposing wall 14 and the second opposing wall 16 such that the diaphragm can be electrostatically pulled toward the second electrode 30 in a rolling action, beginning in the first region. The rolling action may continue with additional activation, as shown in Figure 3 and 4. With the diaphragm 20 pulled away from the valve seat 23, fluid may flow between the first port 42 and the second port or ports 44a and 44b via the one or more openings 25a and 25b in the diaphragm 20, as shown by the arrows in Figure 3.

It is contemplated that the openings 25a and 25b may or may not align with the second ports 44a and 44b when the diaphragm 20 is pulled adjacent the second opposing wall 16. In Figure 4, the openings 25a and 25b are configured to be not aligned with the second ports 44a and 44b. Thus, in the embodiment shown in Figure 4, the fluid flow may begin to slow or stop when the diaphragm 20 is pulled against the second opposing wall 16. In other embodiments, the openings 25a and 25b are configured to be aligned or substantially aligned with the second ports 44a and 44b when the diaphragm 20 is pulled adjacent the second opposing wall 16. In these embodiments, the fluid may continue to flow between the first port 42 and the second ports 44a and 44b when the diaphragm 20 is pulled adjacent the second opposing wall 16.

The rolling action of the diaphragm 20 may significantly reduce the voltage and power required to pull the diaphragm 20 toward the second opposing wall 16, while still achieving a significant diaphragm travel distance. This may be particularly beneficial in, for example, applications where a battery or some other limited power source is used to power the valve 5. A significant diaphragm travel distance may help improve the flow rate that the valve can accommodate, so long as the openings are also appropriately sized.

Figure 5 is a cross-sectional side view of another illustrative normally closed valve in accordance with the present invention. This embodiment is similar to that shown in Figure 1, but includes an additional or third electrode 52 along the first opposing wall 14. The third electrode 52 may be used to provide a restoring force or a supplemental restoring force to the diaphragm 20. For example, once the diaphragm has been displaced toward the second opposing wall 16, a voltage may be applied between the electrode of the diaphragm 20 and the third electrode 52. This may create an attractive electrostatic force between the electrodes, which pulls the diaphragm 20 toward the third electrode 52 and the first opposing wall 14 in a rolling action. The third electrode 52 may also be used to hold the diaphragm 20 against the first opposing wall 14 to keep the valve closed. This may be particular useful when the fluid pressure at the first port 42 may exceed the fluid pressure at the second ports 44a and 44b.

Figure 6 is a cross-sectional side view of yet another illustrative normally closed valve in accordance with the present invention. This embodiment is similar to that shown in Figure 5, but the third electrode 54 is only provided adjacent the valve seat 23. In this embodiment, the third electrode 54 may be used to keep the valve closed, particularly when the fluid pressure at the first port 42 may exceed the fluid pressure at the second ports 44a and 44b.

Figure 7 is a cross-sectional side view of yet another illustrative normally closed valve in accordance with the present invention. In this illustrative embodiment, the first port 80 (e.g. input port) and the second port 82a (e.g. output ports 82a and 82b) are shown extending through a first opposing wall 84 of the valve and into the valve chamber 86. The diaphragm 88 is configured to cover or otherwise restrict fluid from flowing through the first port 80 and into the chamber 86 when the diaphragm 88 is in a first position adjacent the first opposing wall 84. When the diaphragm 88 is electrostatically pulled toward the second opposing wall 90, the diaphragm 88 may move away and uncover the first port 80, thereby allowing fluid to flow between the first port 80 and the second ports 82a and 82b. In this illustrative embodiment, the diaphragm 86 does not have any opening therein, as better shown in Figure 8. Figure 9 is a cross-sectional side view of the illustrative normally closed valve of Figure 7 with the diaphragm at least partially activated. A back pressure relief or vent opening 94 may be provided in the second opposing wall to relieve any back pressure that might arise because of displacement of the diaphragm 88.

This illustrative embodiment may provide an electrostatically actuated valve that does not substantially expose the fluid to the electric field used to electrostatically actuate the valve. In the illustrative embodiment, the electric field used to actuate the valve only extends between the electrode of the diaphragm 88 and the electrode 92 of the second opposing wall 90. In some applications, the dielectric, conductive, polar or other properties of the fluid can affect the magnitude of the electrostatic force between the actuation electrodes of the valve, which can reduce the efficiency and/or reliability of the valve. In addition, the electric field applied between the electrodes of the valve may effect, impact or change the properties of the fluid. This illustrative embodiment may avoid some of these difficulties.

Figure 10 is a cross-sectional side view of an illustrative normally open valve in accordance with the present invention. This illustrative normally open valve is generally shown at 110, and includes a body 112 that is configured to form a chamber 114. The illustrative chamber 112 includes a first opposing wall 116 and a second opposing wall 118. The first opposing wall 116 and the second opposing wall 118 are configured such that the spacing between the first opposing wall 116 and the second opposing wall 118 is smaller in a first region of the chamber 114 than in an adjacent second region. In the illustrative embodiment, the first region is near the edges of the chamber 114 and the second region is away from the edges and near the center of the chamber 114. A diaphragm 120 is mounted between the first opposing wall 116 and the second opposing wall 118.

A first port 122 (e.g. inlet port) and a second port 124 (e.g. outlet port) are provided through the second opposing wall 118 and into the chamber 114. In the illustrative embodiment, a vent 128 is also provided. The vent 128 includes a fluid channel that extends from the first port 122, through the body 112, through the first opposing wall 116, and into the chamber 114.

The diaphragm 120 is mounted in the chamber 114, and has a first position adjacent the first opposing wall 116 that allows fluid to flow between the first port 122 and the second port 124 in the un-actuated state. A first electrode may be secured relative to the diaphragm, and a second electrode 130 may be secured relative to the second opposing wall 118.

Like above, the diaphragm 120 may be adapted to be electrostatically pulled toward the second electrode 130 in a rolling action, beginning in the first region, toward the second opposing wall when a voltage is applied between the electrode of the diaphragm 120 and the electrode 130 of the second opposing wall 118. When actuated, the diaphragm 120 may begin to restrict fluid flow between the first port 122 and the second port 124. Like above, and in some embodiments, the diaphragm 120 is elastically deformed when it is electrostatically pulled toward the second opposing wall 118, and returns to the first position adjacent the first opposing wall under elastic restoring forces.

As can be seen, the diaphragm 120 may separate the chamber 114 into a first part and a second part. The first part extends between the diaphragm 120 and the first opposing wall 116, and the second part extends between the diaphragm 120 and the second opposing wall 118. In the illustrative embodiment, the first part is in fluid communication with the first port 122 via vent 128, and the second part is in fluid communication with the first port 122 and the second port 124, at least when the diaphragm 120 is in the first position. By having both the first part and the second part in fluid communication with the first port 122 (e.g. inlet port), the actuation force required to move the diaphragm from a first position adjacent the first opposing wall 116 to a second position adjacent the second opposing wall may be reduced because there is little or no pressure differential across the diaphragm 120.

Figure 11 is a cross-sectional side view of the illustrative normally open valve of Figure 10 with the diaphragm partially activated. As discussed above, the chamber 114 may have a first opposing wall 116 and a second opposing wall 118, with the second electrode 130 secured relative to the second opposing wall 118. The diaphragm 120 is mounted between the first opposing wall 116 and the second opposing wall 118 such that the diaphragm can be electrostatically pulled toward the second electrode 130 in a rolling action. The rolling action may continue with additional activation, as shown in Figure 11. This rolling action may significantly reduce the voltage and power required to pull the diaphragm 120 toward the second opposing wall 118, while still achieving a significant diaphragm travel distance. Figure 12 is a cross-sectional side view of the illustrative normally open valve of Figure 10 with the diaphragm fully activated. As can be seen, the diaphragm 120 may be sufficiently activated to reduce or even prevent fluid flow between the first port 122 and the second port 124, thereby closing the valve.

Figure 13 is a cross-sectional side view of an illustrative three-way valve in accordance with the present invention. The illustrative three-way valve includes a body 140 that is configured to form a chamber 142. The chamber 142 has a first opposing wall 144 and a second opposing wall 146. A diaphragm 150, which is mounted between the first opposing wall 144 and the second opposing wall 156, may include an opening 152. A first electrode (not explicitly shown but as described above) is secured to the diaphragm 150, and a second electrode 154 is secured to the second opposing wall 146. An inlet port 160 may extend through the first opposing wall 144 and into the chamber 142. A first outlet port 162 may extend through the second opposing wall 146 and into the chamber 142, and a second outlet port 164 may extend through the first opposing wall and into the chamber 142. The inlet port 160 and the second outlet port 164 are shown laterally spaced from one another, with the second outlet port 164 defined by an annular protrusion 166 that extends further into the chamber 142. In some embodiments, a valve seat 170 is provided along the top of the annular protrusion 166.

In Figure 13, the diaphragm 150 is shown in a first position adjacent the first opposing wall 144. The diaphragm 150 extends along the valve seat 170, which helps restrict or otherwise provide a seal between the first opposing wall 144 and the diaphragm 150. Thus, in the first position, the diaphragm 150 allows fluid to flow between an inlet port 160 and the first outlet port 162 through the opening 152, while restricting or preventing fluid from flowing between the inlet port 160 and the second outlet port 164

Figure 14 is a cross-sectional side view of the illustrative three-way valve of Figure 13 with the diaphragm partially activated. As shown, the diaphragm 150 may be electrostatically pulled toward the second electrode 154 in a rolling action when a voltage is applied between the first electrode on the diaphragm 150 and the second electrode 154. The electric field is illustrated at 172. When activated, the diaphragm 150 moves toward the second opposing wall 146, and away from the first opposing wall 144 and the valve seat 170. As the diaphragm 150 moves away from the first opposing wall 144, fluid can flow between the inlet port 160 and the second outlet port 164.

Figure 15 is a cross-sectional side view of the illustrative three-way valve of Figure 14 with the diaphragm fully activated. As shown in Figure 15, when the diaphragm 150 is electrostatically pulled closer to the second opposing wall 146, the opening 152 in the diaphragm 150 begins to become restricted, which restricts and eventually prevents or substantially prevents fluid from flowing between the inlet port 160 and the first outlet port 162. In addition, as the diaphragm 150 is moved away from the first opposing wall 144, the fluid communication path between the inlet port 160 and the second outlet port 164 becomes less restricted, allowing greater flow for a given inlet pressure.

It should be understood that this disclosure is, in many respects, only illustrative. Changes may be made in details, particularly in matters of shape, size, and arrangement of steps without exceeding the scope of the invention. The invention's scope is, of course, defined in the language in which the appended claims are expressed.