CROSS-REFERENCE TO RELATED CASES

[0001] This application claims the benefit of U.S. Provisional Application Serial No. 61/058,265; filed June 3, 2008, the disclosure of which is expressly incorporated herein by reference.

TECHNICAL FIELD

[0002] The present invention relates to a piezo-electric actuated pinch valve used to meter fluid through a fluid flowing through a tube.

BACKGROUND

[0003] Actuators are required in a wide variety of modern applications. For example, valves and relays are used throughout industry, transportation, architecture, etc. Presently, electromagnetic solenoids are used in a wide variety of clamping and valving applications. However, electro-magnetic solenoids have many shortcomings. In general, solenoids are relatively large and heavy. Solenoids consume relatively high amounts of power to remain energized. When supplied with only a reduced amount of power, solenoids operate unpredictably. It is difficult to maintain a solenoid in a partially open or partially closed position. Solenoids have relatively slow cycle times, provide weak opening and closing forces, and generate EMF (electromotive force). Differential pressure is required to operate most solenoids. When designed as

a valve, most solenoids are gravity sensitive and include a fixed inlet valve port and a fixed outlet valve port requiring a predetermined installation orientation.

[0004] Various types of piezo-electric devices are known to those skilled in the art. Many of these devices include complex configurations and are very expensive to manufacture. Other devices include simpler configurations, but are extremely limited in the corresponding maximum range of movement or the corresponding maximum application of force.

SUMMARY

[0005] At least one embodiment of the invention provides a pinch valve comprising: a flexible tube member; a tube housing body which is adapted to support the flexible tube member; a pinch member in direct contact with the flexible tube member; an actuator assembly comprising a piezo-electric member and a displacement amplifying structure; the pinch member operably connected to the displacement amplifying structure of the actuator assembly and movable against the flexible tube member for varying the cross-sectional area of the flexible tube member by pinching the flexible tube member against the tube housing body.

[0006] At least one embodiment of the invention provides a pinch valve comprising: an actuator assembly comprising: a support structure defining a rigid non-flexing portion and a moveable portion and a smart material actuator

for driving the moveable portion of the support structure between first and second positions; a flexible tube member; a tube housing body which is adapted to support the flexible tube member; a pinch member in direct contact with the flexible tube member; the pinch member operably connected to moveable portion of the support structure and movable against the flexible tube member for- varying the cross-sectional area of the flexible tube member by pinching the flexible tube member against the tube housing body, wherein movement of the pinch member is proportional to an input voltage of the actuator assembly.

[0007] At least one embodiment of the invention provides a pinch valve comprising: an actuator assembly comprising: a piezoelectric member and an amplifier device for amplifying moment of the piezoelectric member; at least two flexible tube members; a base member having a tube support portion adapted to support the flexible tube members; a pinch member in direct contact with the flexible tube members, the pinch member positioned between the flexible tube members and biasing the tube members against opposing surfaces of the tube support portion of the base; the pinch member operably connected to a moveable portion of the amplifier device, the pinch member moveable to and between a first position wherein the pinch member completely stops the flow through a first of the at least two flexible tube members when the actuator assembly is not actuated and a second position wherein the pinch member

completely stops the flow through a second of the at least two flexible tube members when the actuator assembly is actuated at a predetermined voltage.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Embodiments of this invention will now be described in further detail with reference to the accompanying drawings, in which: [0009] FIG. 1 is a perspective view of an embodiment of the pinch valve of the present invention;

[0010] FIG. 2 is a side elevational view of the pinch valve shown in FIG. 1 ; [0011] FIG. 3 is an opposite side elevational view of the pinch valve shown in FIG. 1 ;

[0012] FIG. 4 is a side elevational view of the pinch valve showing the pinch valve in a fully actuated position; [0013] FIG. 5 is another perspective view of the pinch valve shown in FIG.

1 ;

[0014] FIG. 6 is a perspective view of an embodiment of an embodiment of the actuator assembly usable in the pinch valve of the present invention; [0015] FIG. 7 is a perspective view of another embodiment of the pinch valve of the present invention having multiple tubes;

[0016] FIG. 8 is a side elevational view of the valve of FIG. 7 in a non- actuated state;

[0017] FIG. 9 is a side elevational view of the valve of FIG. 7 in an actuated state and in an intermediate stroke position; and

[0018] FIG. 10 is a side elevational view of the valve of FIG. 7 in a fully actuated state.

DETAILED DESCRIPTION

[0019] An embodiment of the present invention is shown in FIGS. 1 to 5 as a pinch valve assembly 10. The valve assembly 10 comprises an actuator assembly 20, such as the smart material actuator disclosed in co-owned U.S. Patent No. 6,759,790 issued July 6, 2004 and entitled "Apparatus For Moving Folded-Back Arms Having A Pair Of Opposing Surfaces In Response To An Electrical Aactivation", and herein incorporated by reference. The valve assembly 10 further comprises a moving arm 50 attached to the smart material actuator assembly 20. A tubing holder 30 is attached to the actuator assembly 20 on a side opposite that of the moving arm 50. The tubing holder 30 is adapted to support and hold a tube (not shown). The moving arm 50 has a tubing clamp 40, also referred to as a pinch member or plunger, adjustably connected thereto by the preload adjust screw 42.

[0020] Referring now to FIGS. 2 and 3, the valve assembly 10 is shown in a non-actuated position in which the tubing clamp 40 would fully compress the tube to prevent any flow through the tube. When electricity is applied to the smart material of the actuator assembly 20, the moving arm 50 and attached tubing clamp 40 move upward in proportion to the electrical input to the actuator assembly 20. The full movement of the arm to a fully actuated position is

shown in FIG. 4, wherein the tube is not compressed at all by the tubing clamp 40, allowing full flow through the tube.

[0021] The details of an embodiment of the actuator assembly 20 are shown in a perspective view in FIG. 6. The actuator assembly 20 comprises a support structure defining a rigid non-flexing portion 24 and a moveable portion 26. The rigid non-flexing portion 24 houses a smart material actuator 22 for driving the moveable portion 26 of the support structure between first and second positions. The smart material 22 is shown as a rectangular block and is typically a piezo-electric element. The moveable portion 26 may include one or more arms 28 that are either attached to the moveable portion 26 or integrally formed with the moveable portion 26 as a single piece.

[0022] The pinch valve 10 of the present invention provides the ability to meter flow through a tube that is proportional to the input voltage of the actuator assembly controller. Conventional solenoid-based pinch valves merely provide an on and off capability. The pinch valve 10 of the present invention also utilizes low power consumption, virtually no noise generation, and a longer tube life due to the soft landing of the pinch element because of the capacitive decay rate of the piezo actuator.

[0023] A second embodiment of the invention is shown in FIG. 7 as a multiple tube pinch valve 110. Pinch valve 110 comprises actuator 20 mounted

on base 130, the actuator 20 having a piezoelectric element 22. A first tube, 112 and a second tube 114 are shown positioned on opposite sides of plunger 140 which is attached to arm 28. The plunger 140 may bias the tubes 112 and 114 against opposing support surfaces 132, 134 of the base 130.

[0024] Operation of pinch valve 110 is shown in FIGS. 8-10. Referring now to FIG. 8, pinch valve 110 is shown in an un-actuated state. In this position, the first tube 112 is completely compressed by the plunger 140 and an upper support 132 of base 130 such that no flow passes in the first tube 112 at the pinch valve 110. The second tube 114 is an uncompressed state such that full flow passes through the second tube 114. The plunger 140 is shown in direct contact with the first tube 112 and the second tube 114.

[0025] Referring now to figure 9, a predetermined voltage is applied to the piezoelectric actuator 20 to move arm 28 generally downward such that the pinch valve 110 is shown in an actuated state, at a half-stroke position. In this position, the first tube 112 is compressed by the plunger 140 to allow about 50% of full flow and the second tube 114 is compressed by the plunger 140 to allow about 50% of full flow. The plunger 140 is positioned generally midway between upper support surface 132 and lower support surface 134 of the base 130.

[0026] In FIG. 10, a predetermined voltage is applied to the piezoelectric actuator 20 to move arm 28 further downward such that pinch valve 110 is shown in a fully actuated state. In this position, the first tube 112 is in an uncompressed condition, while the second tube 114 is fully compressed by plunger 140 against lower support surface 134 of the base 130 such that no flow passes through second tube 114 at the pinch valve 110. The plunger 140 is shown in direct contact with the first tube 112 and the second tube 114.

[0027] Although not shown, the pinch valve 110, can be positioned in any number of positions between the un-actuated position and fully actuated position. For example, flow rates of the first tube 112 and the second tube 114 may be 10%, 90%; 20%, 80%; 30%, 70%; 40%, 60%; 60%, 40%; 70%, 30%; 80%, 20%; 90%, 10%, each respectively. It is also contemplated that, different size tubes (or tubes with different properties such as tube deflection rates) can be used such that the flow rates of the tubes are not directly proportional.

[0028] Although the principles, embodiments and operation of the present invention have been described in detail herein, this is not to be construed as being limited to the particular illustrative forms disclosed. They will thus become apparent to those skilled in the art that various modifications of the embodiments herein can be made without departing from the spirit or scope of the invention.