Electroactive polymer devices for controlling fluid flow

• US 20030214199A1
• Filed: 03/05/2003
• Published: 11/20/2003
• Est. Priority Date: 02/07/1997
• Status: Active Grant

• Current Assignee: SRI International, Inc.
• Original Assignee: SRI International, Inc.
• Inventors: Pelrine, Ronald E., Heydt, Richard P., Eckerle, Joseph S., Heim, Jonathan R., Kornbluh, Roy David, Rosenthal, Marcus
• Granted Patent: US 7,320,457 B2
• Time in Patent Office: Days
• US Class Current: 310/309
• CPC Class Codes: F02G 2243/52 acoustic
• CPC Class Codes: F04B 35/045 using solenoids
• CPC Class Codes: F04B 43/043 Micropumps
• CPC Class Codes: H04R 17/005 using a piezoelectric polymer
• CPC Class Codes: H04R 17/08 signals being recorded or played back by vibration of a stylus in two orthogonal directions simultaneously
• CPC Class Codes: H04R 19/02 Loudspeakers H04R19/01 takes precedence
• CPC Class Codes: H04R 23/00 Transducers other than those covered by groups H04R9/00 - H04R21/00 diaphragms for transducers of the distributed-mode type H04R7/045
• CPC Class Codes: H04R 2499/13 Acoustic transducers and sound field adaptation in vehicles
• CPC Class Codes: H04R 5/02 Spatial or constructional arrangements of loudspeakers

Abstract

The invention describes devices for controlling fluid flow, such as valves. The devices may include one or more electroactive polymer transducers with an electroactive polymer that deflects in response to an application of an electric field. The electroactive polymer may be in contact with a fluid where the deflection of the electroactive polymer may be used to change a characteristic of the fluid. Some of the characteristic of the fluid that may be changed include but are not limited to 1) a flow rate, 2) a flow direction, 3) a flow vorticity, 4) a flow momentum, 5) a flow mixing rate, 6) a flow turbulence rate, 7) a flow energy, 8) a flow thermodynamic property. The electroactive polymer may be a portion of a surface of a structure that is immersed in an external fluid flow, such as the surface of an airplane wing or the electroactive polymer may be a portion of a surface of a structure used in an internal flow, such as a bounding surface of a fluid conduit.

Claims

1. A device for controlling fluid flow, the device comprising:

one or more transducers, each transducer comprising at least two electrodes and an electroactive polymer in electrical communication with the at least two electrodes wherein a portion of the electroactive polymer is arranged to deflect from a first position to a second position in response to a change in electric field;

at least one surface in contact with a fluid and operatively coupled to the one or more transducers wherein the deflection of the portion of the electroactive polymer causes a change in a characteristic of the fluid that is transmitted to the fluid via the one surface.

2. The device of claim 1, wherein the characteristic of the fluid is selected from the group consisting of 1) a flow rate, 2) a flow direction, 3) a flow vorticity, 4) a flow momentum, 5) mixing, 6) flow turbulence, 7) fluid energy, 8) a fluid thermodynamic property, 9) a fluid rheological property.

3. The device of claim 1, wherein the deflection of the portion of the electroactive polymer changes the one surface from a first shape to a second shape.

4. The device of claim 1, wherein the one surface is operatively coupled to the one or more transducers via a mechanical linkage.

5. The device of claim 1, wherein the one surface includes the portion of the electroactive polymer.

6. The device of claim 5, wherein the one surface expands to form one of a balloon-like shape, a hemispherical shape, a cylinder shape, or a half-cylinder shape.

7. The device of claim 1, wherein the fluid is one of compressible, incompressible or combinations thereof.

9. The device of claim 1, wherein the fluid is one of a Newtonian or a non-Newtonian fluid.

10. The device of claim 1, wherein the fluid is selected from the group consisting of a gas, a plasma, a liquid, a mixture of two or more immiscible liquids, a supercritical fluid, a slurry, a suspension, and combinations thereof.

11. The device of claim 1, wherein the device is a valve.

12. The device of claim 1, wherein the fluid flows over the one surface.

13. The device of claim 12, wherein the deflection of the portion of the electroactive polymer changes a shape of the one surface to alter a property of a viscous flow layer of the fluid.

14. The device of claim 12, wherein the deflection of the portion of the electroactive polymer changes a shape of the one surface to alter a property of an inviscid flow layer of the fluid.

15. The device of claim 12, wherein the deflection of the portion of the electroactive polymer changes a shape of the one surface to promote mixing of constituents in the fluid.

16. The device of claim 1, wherein the deflection of the portion of the electroactive polymer changes a shape of the one surface to block the fluid flow.

17. The device of claim 1, wherein the deflection of the portion of the electroactive polymer results in a change in temperature of the one surface.

18. The device of claim 1, wherein the deflection of the portion of the electroactive polymer causes a change in a surface roughness of the one surface.

19. The device of claim 1, wherein the one surface further comprises an array of microscopic electroactive polymer elements and wherein a deflection of the microscopic electroactive polymer elements from a first position to a second position changes a surface roughness of the one surface.

20. The device of claim 1, wherein the deflection of the portion of the electroactive polymer causes the one surface to stretch or contract to alter a relative smoothness of the one surface.

21. The device of claim 20, wherein the relative smoothness of the one surfaces affects a drag on the fluid flow over the one surface.

22. The device of claim 1, further comprising a fluid conduit configured to allow fluid to flow from an inlet of the fluid conduit to an exit of the fluid conduit and pass over the one surface between the inlet and the exit and wherein a bounding surface of the fluid conduit separates the fluid from an outer environment.

23. The device of claim 22, wherein the one surface is includes the portion of the electroactive polymer and wherein the one surface is a portion of the bounding surface of the fluid conduit.

24. The device of claim 22, wherein the deflection of the portion of the electroactive polymer causes a change in a shape of the bounding surface of the fluid conduit.

25. The device of claim 24, wherein the shape of the bounding surface of the fluid conduit is changed to increase the distance the fluid travels from the inlet to the exit.

26. The device of claim 24, wherein the shape of the bounding surface of the fluid conduit is changed dynamically as a function of time.

27. The device of claim 24, wherein the shape of the bounding surface of the fluid conduit is changed to increase or decrease a cross-sectional area of a section of the fluid conduit.

28. The device of claim 27, wherein a shape of the cross-sectional area is selected from the group consisting of circular, ovular, rectangular and polygonal.

29. The device of claim 22, wherein the bounding surface of the fluid conduit is comprised of a rolled electroactive polymer transducer with a hollow center.

30. The device of claim 22, wherein one or more transducers are arranged to deflect in a manner that pinches a section of the fluid conduit to block the fluid flow in the conduit.

31. The device of claim 30, wherein the one or more transducers are configured in a sleeve designed to fit over an outer perimeter of the section of the fluid conduit.

32. The device of claim 30, wherein the fluid conduit is one of a blood vessel or a human organ.

33. The device of claim 22, wherein the deflection in the portion of the electroactive polymer causes the one surface to expand to one of block, increase or decrease the flow in the fluid conduit.

34. The device of claim 22, wherein the deflection in the portion of the electroactive polymer causes the one surface to expand to divert flow in the fluid conduit from a first channel to a second channel connected to the fluid conduit.

35. The device of claim 22, wherein a portion of the fluid conduit is a nozzle body for expanding the fluid from a throat area in the fluid conduit to an exit of the nozzle body.

36. The device of claim 35, wherein the deflection in the portion of the electroactive polymer causes the nozzle body to expand or contract to change an expansion rate of the fluid in the nozzle body and a velocity profile of the fluid at the exit of the nozzle body.

37. The device of claim 35, wherein the deflection of the portion of the electroactive polymer causes a cross sectional shape of the nozzle body to change from a first shape to a second shape.

38. The device of claim 35, wherein the deflection of the portion of the electroactive polymer causes a cross sectional shape of the throat area to change from a first shape to a second shape.

39. The device of claim 35, wherein the deflection of the portion of the electroactive polymer causes the nozzle body to bend to change a direction of the fluid exiting the nozzle.

40. The device of claim 22, wherein shapes of two or more portions the bounding surface of the fluid conduit are changed independently in response to the deflection of the portion of the electroactive polymer.

41. The device of claim 22, wherein the deflection of the portion of the electroactive polymer causes a bounding surface of the polymer to rotate torsionally.

42. The device of claim 1, further comprising one or more sensors connected to the device for measuring a property of the fluid.

43. The device of claim 42, wherein the property of the fluid is selected from the group consisting of a temperature, a pressure, a density, a viscosity, a thermal conductivity, a flow rate, and a concentration of a constituent of the fluid.

44. The device of claim 1, further comprising one or more sensors connected to the device for monitoring one or more of the deflection of the portion of the polymer, a charge on the portion of the polymer, and a voltage across the portion of the electroactive polymer.

45. The device of claim 1, further comprising a logic device for at least one of:

1) controlling operation of the transducer,

     2) monitoring one or more sensors,

     3) communicating with other devices, and

     4) combinations thereof.

46. The device of claim 1, further comprising conditioning electronics designed or configured to perform one or more of the following functions for the one or more transducers:

voltage step-up, voltage step-down and charge control.

47. The device of claim 1, wherein the electroactive polymer comprises a material selected from the group consisting of a silicone elastomer, an acrylic elastomer, a polyurethane, a copolymer comprising PVDF, and combinations thereof.

48. The device of claim 1, further comprising:

an insulation barrier designed or configured to protect the one surface from constituents of the fluid in contact with the one surface.

49. The device of claim 1, further comprising:

one or more support structures designed or configured to attach to the one or more transducers.

50. The device of claim 1, wherein the electroactive polymer is elastically pre-strained at the first position to improve a mechanical response of the electroactive polymer between the first position and second position.

51. The device of claim 1, wherein the electroactive polymer has an elastic modulus below about 100 MPa.

52. The device of claim 1, wherein the electroactive polymer has an elastic area strain of at least about 10 percent between the first position and the second position.

53. The device of claim 1, wherein the electroactive polymer comprises a multilayer structure.

54. The device of claim 53, wherein the multilayer structure comprises two or more layers of electroactive polymers.

55. The device of claim 1, wherein the device is a MEMS device.

56. The device of claim 1, wherein the one surface is part of a surface of a vane for controlling a direction of the fluid flow.

57. The device of claim 56, wherein the deflection of the portion of the electroactive polymer changes an orientation of the vane.

58. A valve comprising:

one or more transducers, each transducer comprising at least two electrodes and an electroactive polymer in electrical communication with the at least two electrodes wherein a portion of the electroactive polymer is arranged to deflect from a first position to a second position in response to a change in electric field;

an inlet and an exit for allowing a fluid to enter the valve and exit the valve;

a flow path between the inlet and the exit that allows the fluid to pass through the valve;

a structure operatively coupled to the one or more transducers wherein the deflection of the portion of the electroactive polymer causes an operating position of the structure to change and wherein a change in the operating position of the structure changes the flow path.

59. The valve of claim 58, wherein the structure is designed to have a first operating position and a second operating position.

60. The valve of claim 59, wherein when the structure is in the first operating position, the flow path is closed and wherein when the structure is in the second operating position, the flow path is open.

61. The valve of claim 58, wherein the structure is designed to have a plurality of operating positions.

62. The valve of claim 58, wherein the change in the operating position of the structure changes a cross-sectional area of the flow path for at least one location along the flow path.

63. The valve of claim 58, further comprising:

a valve seat wherein the deflection of the portion of the electroactive polymer causes the structure to contact the valve seat.

64. The valve of claim 58, wherein the structure further comprises a fluid conduit that is a section of the flow path.

65. The valve of claim 64, wherein the valve is a ball valve and the structure is spherical in shape.

66. The valve of claim 64, wherein the valve is a plug valve and the structure is plug-shaped.

67. The valve of claim 64, wherein the deflection of the portion of the polymer causes the structure to rotate from a first operating position to a second operating position.

68. The valve of claim 67, wherein in the first operating position the fluid conduit is aligned with the flow path outside of the structure and the flow path through the valve is open.

69. The valve of claim 67, wherein in the second operating position the fluid conduit is not aligned with the flow path outside of the structure and the flow path through the valve is blocked.

70. The valve of claim 64, wherein the deflection of the portion of the electroactive polymer causes the structure to move linearly from a first operating position to a second operating position.

71. The valve of claim 70, wherein in the first operating position the fluid conduit is aligned with the flow path outside of the structure and the flow path through the valve is open.

72. The valve of claim 70, wherein in the second operating position the fluid conduit is not aligned with the flow path outside of the structure and the flow path through the valve is blocked.

73. The valve of claim 70, wherein the valve is a slot valve and the fluid conduit is a slot.

74. The valve of claim 58, wherein the valve is a diaphragm valve and the structure is a diaphragm.

75. The valve of claim 58, wherein the valve is a diaphragm valve and the structure is the electroactive polymer in a shape of a diaphragm.

76. The valve of claim 58, wherein the valve is a needle valve and the structure is a conical in shape.

77. The valve of claim 58, wherein the electroactive polymer is a part of the structure.

78. The valve of claim 58, wherein the structure is an electroactive polymer roll.

79. The valve of claim 58, wherein a section of the flow path is through the center of the polymer roll.

80. The valve of claim 58, wherein the portion of the electroactive polymer is a bounding surface along the flow path.

81. The valve of claim 58, further comprising:

one or more sensors.

82. The valve of claim 81, wherein an input signal from the one or more sensors is used to determine the operating position of the structure.

83. The valve of claim 58, wherein the valve is a multi-port valve and the operating position of the structure allows the flow path to align with one of a plurality of ports.

84. The valve of claim 58, wherein the valve is selected from the group consisting of a check valve, a buttery fly valve, a pressure relief valve, a needle valve, a control valve, a slot valve, a rotary valve, a pinch valve, an engine in-take valve and an engine exhaust valve.

85. The valve of claim 58, further comprising a logic device for at least one of:

1) controlling operation of the valve,

     2) monitoring one or more sensors,

     3) communicating with other devices, and

     4) combinations thereof.

86. The valve of claim 58, further comprising conditioning electronics designed or configured to perform one or more of the following functions for the one or more transducers:

voltage step-up, voltage step-down and charge control.

87. The valve of claim 58, wherein the polymer comprises a material selected from the group consisting of a silicone elastomer, an acrylic elastomer, a polyurethane, a copolymer comprising PVDF, and combinations thereof.

88. The valve of claim 58, further comprising:

an insulation barrier designed or configured to protect the structure from constituents of the fluid in contact with the structure.

89. The valve of claim 58, further comprising:

one or more support structures designed or configured to attach to the one or more transducers.

90. The valve of claim 58, wherein the electroactive polymer is elastically pre-strained at the first position to improve a mechanical response of the electroactive polymer between the first position and second position.

91. The valve of claim 58, wherein the electroactive polymer has an elastic modulus below about 100 MPa.

92. The valve of claim 58, wherein the electroactive polymer has an elastic area strain of at least about 10 percent between the first position and the second position.

93. The valve of claim 58, wherein the polymer comprises a multilayer structure.

94. The valve of claim 93, wherein the multilayer structure comprises two or more layers of electroactive polymers.

95. The valve of claim 58, wherein the device is fabricated on a semiconductor substrate.

96. The valve of claim 58, wherein the deflection of the portion of the electroactive polymer changes the structure from a first shape to a second shape.

97. The valve of claim 58, wherein the structure is operatively coupled to the one or more transducers via a mechanical linkage.

98. The valve of claim 58, further comprising:

a force mechanism which provides a force in a direction opposite to a direction of a second force applied to the structure by the deflection of the portion of the electroactive polymer.

99. The valve of claim 98, wherein the force mechanism is a spring.

100. The valve of claim 58, wherein the fluid is selected from the group consisting of a gas, a plasma, a liquid, a mixture of two or more immiscible liquids, a supercritical fluid, a slurry, a suspension, and combinations thereof.

101. The valve of claim 58, wherein the valve is used in an automobile system.

102. The valve of claim 101, wherein the valve the automobile system is selected from the group consisting of a fuel injection system, a cooling system, an air intake control system, a combustion system and an emission control system.

103. The valve of claim 101, wherein the valve is used in a combustion system for providing variable valve timing.