Actuators and apparatus

• US 6,515,382 B1
• Filed: 11/03/1999
• Issued: 02/04/2003
• Est. Priority Date: 03/03/1998
• Status: Expired due to Term

• Current Assignee: Adaptive Materials Technology Oy
• Original Assignee: Adaptive Materials Technology Oy
• Inventors: Ullakko, Kari M
• Primary Examiner(s): Mullins, Burton S.
• Application Number:
  US09/434,357
• Time in Patent Office: 1,189 Days
• Field of Search: 310/26, 333/148, 333/201, 335/3, 335/215, 336/20, 367/156, 367/168, 361/206, 318/118
• US Class Current: 310/26
• CPC Class Codes: C08L 2201/12 Shape memory
• CPC Class Codes: F16D 2121/28 using electrostrictive or magnetostrictive elements, e.g. piezoelectric elements
• CPC Class Codes: F16D 2121/32 using shape memory or other thermo-mechanical elements
• CPC Class Codes: F16D 65/14 Actuating mechanisms for brakes; Means for initiating operation at a predetermined position brake control systems, parts thereof B60T
• CPC Class Codes: H01H 2300/034 using magnetic shape memory [MSM] also an austenite-martensite transformation, but then magnetically controlled
• CPC Class Codes: H02N 2/023 Inchworm motors
• CPC Class Codes: H02N 2/101 using intermittent driving, e.g. step motors
• CPC Class Codes: H10N 35/00 Magnetostrictive devices integrated devices or assemblies of multiple devices H10N39/00
• CPC Class Codes: H10N 35/101 with mechanical input and electrical output, e.g. generators, sensors

Abstract

The present invention relates to actuators, linear motors and rotational motors based on magnetic-field-induced strains taking place in the actuator material. These strains are caused by the reorientation of the twin structure of the actuator materials by the applied magnetic field.

Claims

1. An apparatus comprising an active element made from a material having variants separated by a twin boundary, the active element having a shape, the material having both an energy needed to reorient the variants and a magnetocrystalline anisotropy energy, the magnetocrystalline anisotropy energy being sufficient with respect to the energy needed to reorient the variants to change the shape of the active element in response to a predetermined vector force of an external magnetic field, wherein the shape of the active element is coupled to the external magnetic field.

2. An apparatus according to claim 1, further comprising one or more devices adapted for assisting with reorientating the twin variants and reduce the magnitude of the external magnetic field, wherein the devices are selected from the group consisting of devices that produce bias magnetic fields, devices that produce mechanical preload, devices that produce magnetic flux paths, and devices that guide the magnetic field to the active element.

3. An apparatus according to claim 1, wherein mechanical loading of the active elements reorients the variants and produce a measurable change in the vector force of the external magnetic field.

4. An apparatus according to claim 3, further comprising a device adapted for determining the shape of the active element by the change in the vector force of the external magnetic field.

5. An apparatus according to claim 4, wherein the active element is at least a part of a device selected from the group comprising a positioning device, a keyboard, and a joystick.

6. An apparatus according to claim 4, further comprising at least one magnetic field sensor the adapted for determining the change in the vector force of the external magnetic field.

7. An apparatus according to claim 4, wherein the apparatus is a micromechanical device and the material of the active element is a thin film.

8. An apparatus according to claim 7, wherein the thin film is located on a substrate.

9. An apparatus according to claim 3, further comprising a magnetic-to-electric conversion device adapted for converting the measurable chance in the vector force of the external magnetic field to electric current.

10. An apparatus according to claim 9, wherein the magneticto-electric conversion device is a coil connected to an electric circuit.

11. An apparatus according to claim 10, further comprising a device that converts electric power generated by the electric current to other forms of energy.

12. An apparatus according to claim 3, further comprising a sensor adapted for detecting the measurable change in the vector force of the external magnetic field to enable the apparatus to monitor forces, acceleration and vibrations.

13. An apparatus according to claim 12, wherein the apparatus generates electric power from the monitored mechanical vibrations.

14. An apparatus according to claim 3, wherein the actuating element and flux paths are composed of thin sheets attached together with an electrically insulating layer to decrease eddy current losses of the material caused by an alternating magnetic field.

15. An apparatus according to claim 3, wherein the active element are placed in a matrix made from metallic, ceramic or polymeric material to form a composite structure.

16. An apparatus according to claim 1, further comprising an actuating element that includes the active element, wherein the predetermined vector force of the external magnetic field changes the shape of the active element to produce force and motion.

17. An apparatus according to claim 14, wherein the shape changes induced by the applied magnetic field are due to causes selected from the group consisting of:

(1) changes of twin variant proportions in different orientations by inducing a shear strain whose shear plane is substantially parallel to the twin boundary when the vector force of the external magnetic field energy is sufficiently high; and

(2) changes of the martensite/twin variant proportions in different orientations when the magnetocrystalline anisotropy energy of the material of the actuating element is sufficiently high to orient growing of the relative martensite/twin variant proportion that are in the favourable orientation in relation to the vector force of the external magnetic field.

18. An apparatus according to claims 16, further comprising one or more magnetic field sources that apply magnetic fields of a suitable vector force to the actuating element, the one or more magnetic field sources including at least one bias source selected from the group that consists of:

sources that produce bias magnetic fields, devices that produce mechanical pre-load, and devices that produce magnetic flux paths that guide the magnetic field to the actuating element.

19. An apparatus according to claim 18, wherein one or more of the sources that produce bias magnetic fields are static.

20. An apparatus according to claim 18, wherein the magnetic field source is placed in such a way that the magnetic field applied to the actuating element produces a shape change in the actuating element.

21. An apparatus according to claim 20, wherein at least one of the one or more magnetic field sources is placed in a way selected from the group consisting of:

(1) a way that the magnetic field is substantially parallel with the longest dimension of the actuating element;

(2) a way that the shape change is largest; and

(3) a way that the magnetic field makes an angle of 0 to 90 degrees with the direction of the longest dimension of the actuating element.

22. An apparatus according claim 18, wherein a vector force of an applied magnetic field induced by the one or more magnetic field source in one of the following manners selected from the group consisting of:

(1) the direction of the vector force changes in relation to the direction of the longest dimension of the actuating element in such a way that the absolute value of the magnetic field remains constant;

(2) the direction and absolute value of the vector force change in relation to the direction of the longest direction of the actuating element;

(3) the direction of the vector force rotates around an axis perpendicular to the direction of the longest dimension of the actuating element; and

(4) the direction of the vector force either flips instantly or turns gradually between the direction of the longest direction of the actuating elements and the direction perpendicular or any part of that angle.

23. An apparatus according to claim 16, wherein the magnetic-field-induced shape change of the actuating element is shear.

24. An apparatus according to claim 23, wherein the external magnetic field is oriented in such a direction that a desired shear strain is obtained.

25. An apparatus according to claim 23, wherein the external magnetic field is aligned substantially parallel with a shear plane of the actuating element.

26. An apparatus according to claim 4, wherein the shear strain induced by deformation of the active element is used to generate a change of the external magnetic field.

27. An apparatus according to claim 16, wherein the variants in the active element have been oriented by cooling the active element below martensite start temperature under load.

28. An apparatus according to claim 16, wherein the external magnetic field bends the actuating element.

29. An apparatus according to claim 28, wherein the actuating element has a midpoint with a tangent and the vector force of the external magnetic field is substantially parallel with the tangent.

30. An apparatus according to claim 28, wherein the vector force direction selected so that the desired bending strain is obtained.

31. An apparatus according to claim 28, wherein the actuating element has a midpoint with a tangent and the vector force of the external magnetic field makes an angle 0 to 90 degrees with the tangent in a plane determined by the tangent and the axis perpendicular to the tangent plane.

32. An apparatus according to claim 28, wherein the actuating element has a midpoint with a tangent and the vector force of the external magnetic field makes an angle 0 to 90 degrees with the axis perpendicular to the tangent plane in the midpoint of the actuating element.

33. An apparatus according to any of claim 28, wherein the magnetic field is led through the actuating element.

34. An apparatus according to claim 28, wherein the actuating element has a midpoint with a tangent and the magnetic field produces an effect selected from the group consisting of:

(1) the magnetic field rotates around substantially perpendicular to the direction of the tangent in the midpoint of the actuating element or to the tangent plain in the midpoint of the actuating element and (2) the magnetic field flips instantly or turns gradually between the direction of the tangent in the midpoint of the actuating element and the direction perpendicular to it or part of that angle.

35. An apparatus according to claim 28, wherein the bent actuating element has legs and the angle between the legs is smaller than 90 degrees.

36. An apparatus according to claim 28, wherein the magnetic-field induced shape change of the actuating element is torsion.

37. An apparatus according to claim 16, wherein the actuating element is selected from a group consisting of a solid bar, a hollow bar and a circular tube.

38. An apparatus according to claim 16, wherein the actuating element is hollow and the magnetic field is led radially through a wall of the hollow actuating element.

39. An apparatus according to claim 16, wherein the magnetic field is induced by a toroidically wound coil to produce torsion deformation of the actuating element.

40. An apparatus according to claim 16, wherein the actuating element is placed in a predetermined condition selected from the group consisting of the following:

(1) a bias condition wherein the actuated element is biased by a static magnetic field to obtain a desired torsional strain in the applied driving magnetic field;

(2) a pre-stress condition wherein the actuated element is pre-stressed torsionally to obtain twin structure aligned optimally for producing desired torsional strains in applied magnetic field;

(3) a loaded condition wherein the actuating element is loaded in such a way that twin variants are aligned so that desired strain (e.g., maximal strain) is obtained in the applied magnetic field; and

(4) a martensite condition wherein the actuating element operates at a temperature above Ms (martensite start temperature) and is superelastic martensite transformed from austenite by a load.

41. An apparatus according to claim 16, wherein the shape of the actuating element due to the application of the magnetic field is at least one shape-changing force selected from the group consisting of extension, contraction, bending, twisting and shear.

42. An apparatus according to claim 41, wherein the shape of the actuating element in one part of the element is one type of shape-changing force and another type of shape-change force in other parts.

43. An apparatus according to claim 16, wherein the actuating element is improved by deformation at appropriate temperatures and magnetic fields and cycling the treatment as necessary to produce desired shape changes.

44. An apparatus according to claim 16, wherein the magnetic field rotates around an axis.

45. An apparatus according to claim 16, wherein the magnetic field is produced by a magnetic field source selected from the group of electromagnets coils, and permanent magnets.

46. An apparatus according to claim 45, wherein the actuating element and magnetic field source are connected together by magnetic flux paths.

47. An apparatus according to claim 46, wherein the actuating element is a closed loop that forms a closed flux path for the magnetic field source, and wherein the magnetic field is led to the loop by an external magnetic field whose intensity and direction are suitable to cause a desired shape change of the loop.

51. An apparatus according to claim 46, wherein the actuating element is loaded by changing the shape of the loop.

52. An apparatus according to claim 16, wherein the reorientation that changes the shape of the actuating element is induced by an internal magnetic field due to ordering of the magnetic structure caused by a process selected from the group of cooling the material below its Curie temperature, applying mechanical stress and passing electric current through the material.

53. An apparatus according to claim 16, wherein the actuating element is an actuator selected from the group of:

(1) an actuator designed to produce mechanical vibration;

(2) a shaker adapted for use in tools;

(3) an actuator adapted to be used in cleaning;

(4) an actuator adapted for operating at ultrasonic frequencies;

(5) an actuator adapted for producing vibration in structures and intermedia;

(6) a loud speaker;

(7) a source of counter vibrations in active vibration control apparatus; and

(8) a motor.

54. An apparatus according to claim 53, wherein the motor is a linear motor adapted to provide linear motion comprised of successive steps produced by a motion of either an apparatus or a main actuator and at least one auxiliary actuator.

55. An apparatus according to claim 54, wherein one of the at least one auxiliary actuator is fixed at first end and another auxiliary actuator is fixed at a second end of the main actuator, the auxiliary actuators being designed to clamp by turns on a guide, wherein the main actuator travels along the guide and the auxiliary actuators are synchronous to the back and forth motion of the main actuator, the steps of the linear motion on the guide being generated when one auxiliary actuator is clamped during the extension phase of the main actuator and the other auxiliary actuator is clamped during the reverse motion of the main actuator.

56. An apparatus according to claim 55, wherein the speed of the linear motion is designed to be controlled by the motion of the main actuator, and the direction of the linear motion is reversed by reversing the phase of the clamping of the auxiliary actuators.

57. An apparatus according to claim 55, wherein the auxiliary actuators have a design selected from the group consisting of:

(1) a design wherein the auxiliary actuators are clamped on one guide bar and the main actuator is beside the bar;

(2) a design wherein the auxiliary actuators are clamped on two parallel guide bars and the main actuator is placed symmetrically between the bars; and

(3) a design wherein the auxiliary actuators are clamped inside a tube and the linear motor is inside the tube.

58. An apparatus according to claim 54, wherein the guide bar passes through a hole made in an actuator component of the main actuator and the auxiliary actuators are designed to clamp on the same guide bar.

59. An apparatus according to claim 54, wherein the motion of the main actuator occurs at a frequency selected from the group consisting of:

(1) a frequency that is the mechanical resonance of the longitudinal vibration modes of the actuator component;

(2) a frequency that is the mechanical resonance of those actuators; and

(3) a frequency that is the mechanical resonance of the whole structure of the linear motor.

60. An apparatus according to claim 54, wherein the main and auxiliary actuators are driven by electromagnets operate in an electromagnetic resonance at the same frequency as the mechanical resonance of the main and auxiliary actuators.

61. An apparatus according to claim 54, wherein the main and auxiliary actuators are driven by electromagnets that are digitally controlled to optimise the timing of the clamping and maximise precision, speed and force of the motion of the motor.

62. An apparatus according to claim 53, wherein the motor is a rotational motor whose rotational motion is composed of successive steps produced by a torsional motion of a main actuator and, when necessary by one or more auxiliary actuators.

63. An apparatus according to claim 62, wherein the auxiliary actuators are fixed at both ends of the main actuator and clamp by turns on a guide, around which the main actuator rotates, synchronous to the back and forth torsional motion of the main actuator.

64. An apparatus according to claim 62, wherein the speed of the angular motion is controlled by changing the frequency or amplitude of the main actuator, and the direction of the angular motion is reversed by reversing the phase of the clamping of the auxiliary actuators.

65. An apparatus according to claim 62, wherein the step of the angular motion is generated by one or several main actuators that are placed tangentially on a circle centered around the rotational axis and produce a back and forth extensive motion.

66. An apparatus according to claim 62, wherein the back and forth torsional motion of the main actuator is designed to occur at a frequency that is the mechanical resonance of torsional vibration mode of the axis of the main actuator and/or the back and forth motion of the main actuator is designed to occur at a frequency that is the mechanical resonance of the main actuator and/or the back and forth motion of the auxiliary actuators occurs at a frequency that is the mechanical resonance of those actuators.

67. An apparatus according to claim 62, wherein the main and auxiliary actuators are designed to operate at the same frequency that is the mechanical resonance of the whole structure of the vibrating parts of the motor.

68. An apparatus according to claim 62, wherein the electromagnets operate in an electromagnetic resonance at the same frequency as the mechanical resonance of the main and auxiliary actuators drive the motor.

69. An apparatus according to claim 62, wherein there is a guide and the motor is the rotating axis of the motor.

70. An apparatus according to claim 62, wherein the rotational motion is generated by successive steps produced by torsional twisting of a main actuator of the motor controlled by a magnetic field, two auxiliary actuators being fixed at both ends of the main actuator.

71. An apparatus according to claim 62, wherein the speed of the angular motion is controlled by the frequency or amplitude of the main actuator, and the direction of the angular motion is reversed by reversing the phase of the clamping of the auxiliary actuators.

72. An apparatus according to claim 62, wherein the driving coil of the main actuator is placed around the axis of the motor to produce a magnetic field in the direction of the rotation axis of the motor.

73. An apparatus according to claim 62, wherein the magnetic fields driving the actuators of the motor are in the direction perpendicular to the rotation axis of the motor.

74. An apparatus according to claim 62, wherein the auxiliary actuators are designed to clamp on bars fixed at both ends of the twisting component of the main actuator, wherein the bars are selected from a group consisting of cylindrical bars or polygonal bars.

75. An apparatus according to claim 74, wherein the bars are expanded radially in a magnetic field.

76. An apparatus according to claim 62, wherein the back and forth torsional motion of the main actuator is designed to occur at a frequency that is the mechanical resonance of the torsional vibration modes of the actuator component of the main actuator, the back and forth motion of the auxiliary actuators is designed to occur at a frequency that is the mechanical resonance of those actuators or at the same frequency that is the mechanical resonance of the whole structure of the vibrating parts of the motor.

77. An apparatus according to claim 62, wherein the main and auxiliary actuators are driven by electromagnets that operate in an electromagnetic resonance at the same frequency as the mechanical resonance of the main and auxiliary actuators drive the motor.

78. An apparatus according to claim 53, wherein one or more of the actuators are designed to form a system of a positioning apparatus for moving a certain part accurately and fast to a position in three dimensions.

79. An apparatus according to claim 78, wherein the actuators have a design selected from the group of:

(1) actuators adapted to fasten, tighten and clamp parts together;

(2) actuators adapted to be used in robots and manipulators to produce fast and precise motion that can be actively controlled using information obtained by sensors;

(3) actuators adapted to be used in aircraft to control wing flaps;

(4) actuators adapted to be used in weapon systems to direct weapons;

(5) actuators adapted to be used in control systems to produce fast and precise motion that can be actively controlled using information obtained from sensors;

(6) actuators adapted to be used in elevators;

(7) actuators adapted to be used to generate mechanical vibrations in intermedia;

(8) actuators adapted to be used to produce countervibrations to actively control vibrations and noise;

(9) actuators adapted to be used actively balance a machine by moving the gravity center of a rotating machine element;

(10) actuators adapted to be used to actively control the angular vibrations of rotating parts of machines by producing angular countervibrations;

(11) actuators adapted to be used to contact electrical current;

(12) actuators adapted to be used to regulate a fluid flow;

(13) actuators adapted to be used in pumps;

(14) actuators adapted to be used to regulate the flow of fluid by producing motion for an injector needle;

(15) actuators adapted to be used to produce motion in valve lifters for engines;

(16) actuators adapted to be used within active suspension of vehicles and equipment;

(17) actuators adapted to be used in surgery instruments; and

(18) actuators adapted to be used in artificial organs.

80. An apparatus according to claim 1, wherein the active element forms part of an actuator selected from the group consisting of a micromechanical actuator, an actuator designed to contact electric current, an actuator designed to control the mutual position of capacitor plates, a regulator designed to regulate a flow of a fluid by changing a flow channel cross section, a pump for transferring fluids, and an actuator designed to couple two or more bodies together.

81. An apparatus according to claim 80, wherein the regulator has a design for regulating flow within a flow channel selected from the group consisting of (1) a design for regulating flow by changing the shape of an actuating element that is placed inside the flow channel using a magnetic field source that is installed outside the flow channel and (2) a design for regulating flow by turning plates inside the flow channel.

82. An apparatus according to claim 81, wherein the actuator is designed to couple two or more bodies together and is selected from a group of actuators consisting of:

(1) a moving or rotating bar wherein the bar is coupled from outside using a magnetic field source installed around the bar;

(2) an actuator placed between a moving or rotating bar and another body to be coupled;

(3) an actuator adapted to press against at least one side of a rotating disc;

(4) the rotating disc itself coupled with a magnetic field source installed around the disc;

(5) an actuator adapted to press against opposing inside walls of a moving or rotating open cylinder;

(6) at least one actuator adapted to press against one rotating disc in a plurality of positions to couple the rotating disc with another coaxial rotating disc;

(7) a break;

(8) a connector; and

(9) a coupler.

48. An apparatus according to claim 48, wherein the actuating element is an open loop that forms a flux path for the driving magnetic field, and wherein the magnetic field is led to the loop by an external magnetic field whose intensity and direction are suitable to cause a desired shape change of the loop.

49. An apparatus according claim 48, wherein the driving magnetic field is generated by a coil wound around one part of the ring toroidically.

50. An apparatus according to claim 48, wherein the magnetic field is led to the open loop through the ends of the loop.