Ultrasonic motors
AssigneeCranfield University
InventorsPhilip J. Rayner, Roger W Whatmore
Life of this patent
Estimating the term…
Abstract
An ultrasonic motor is described which uses radial vibrations of an electro-active material disc (7) amplified by one or more flextensional diaphragms (6) to drive a rotor (4) pressed in frictional contact with the diaphragm (6) by a force imposed by a spring (3) or magentic attraction. The vibrations are converted by elastic fins (5) into rotary motion of the rotor (4). The motor can be operated in any resonant mode that generates vibration at the surface perpendicular to the contact area. Versions of the motor with one or two rotors are disclosed with the two rotor version being used to produce an output in the same direction or opposite directions.
Claims31
An ultrasonic motor comprising:
- a disc of electro-active material (7,11) for producing radial vibrations;
- at least one flextensional displacement amplifier diaphragm (6a,6b,13) for converting the radial vibrations into vibrations of the diaphragm (6a,6b,13) perpendicular to the plane of the disc (7,11), the diaphragm mounted on the disk;
- a rotor (4,4a,4b,14) coupled to the diaphragm, the diaphragm vibrations then being converted into rotary motion via frictional contact at a diaphragm/rotor interface (6b/4,11/14);
- elastic fins (5,5a,5b) each having a fin tip which contacts the friction interface such that, the fin tip has an instantaneous rotation about a rotation point not in line with the fin tip contact point in the direction of rotation, thus causing a horizontal friction reaction which drives the rotor (44a,4b,14) on an expansive stroke of the amplifier (6a,6b,13), yet allows the fin to relax on a downstroke and the fin tip to slide on the friction interface.
An ultrasonic motor comprising:
- a disc of electro-active material (7,11) for producing radial vibrations;
- at least one flextensional displacement amplifier diaphragm (6a,6b,13) for converting the radial vibrations into vibrations of the diaphragm (6a,6b,13) perpendicular to the plane of the disc (7,11), the diaphragm mounted on the disk;
- a rotor (4,4a,4b,14) coupled to the diaphragm, the diaphragm vibrations then being convened into rotary motion via frictional contact at a diaphragm/rotor interface (6b/4,11/14);
- wherein a respective diaphragm (6a,6b) is attached to each side of the disc (7) and a respective rotor (4a,4b) is arranged opposite each diaphragm (6a,6b) of which one rotor (4b) is attached to an axle and the other rotor (4a) can slide axially along the axle.
An ultrasonic motor comprising:
- a disc of electro-active material (7,11) for producing radial vibrations;
- at least one flextensional displacement amplifier diaphragm (6a,6b,13) for converting the radial vibrations into vibrations of the diaphragm (6a,6b,13) perpendicular to the plane of the disc (7,11), the diaphragm mounted on the disk;
- a rotor (4,4a,4b,14) coupled to the diaphragm, the diaphragm vibrations then being converted into rotary motion via frictional contact at a diaphragm/rotor interface (6b/4,11/14);
- wherein one or more rotors (4a,4b,14) are held in contact with the oscillating surfaces of the diaphragm by magnetic attraction brought about by the rotors (4a,4b,14) having a remnant magnetic polarization and the diaphragms (6a,6b,13) being made of ferromagnetic materials, such as the metals Iron, Nickel or Cobalt or their alloys.
An ultrasonic motor comprising:
- a disc of electro-active material (7,11) for producing radial vibrations;
- at least one flextensional displacement amplifier diaphragm (6a,6b,13) for converting the radial vibrations into vibrations of the diaphragm (6a,6b,13) perpendicular to the plane of the disc (7,11), the diaphragm mounted on the disk;
- a rotor (4,4a,4b,14) coupled to the diaphragm, the diaphragm vibrations then being converted into rotary motion via frictional contact at a diaphragm/rotor interface (6b/4,11/14);
- wherein one or more rotors (4a,4b,14) are held in contact with the oscillating surfaces of the diaphragm by magnetic attraction brought about by the diaphragms (6a,6b,13), having a remnant magnetic polarization and the rotors (4a,4b,14) being made of ferromagnetic materials, such as the metals Iron, Nickel, or Cobalt or their alloys.
An ultrasonic motor comprising:
- a disc of electro-active material (7,11) for producing radial vibrations;
- at least one flextensional displacement amplifier diaphragm (6a,6b,13) for converting the radial vibrations into vibrations of the diaphragm (6a,6b,13) perpendicular to the plane of the disc (7,11), the diaphragm mounted on the disk;
- a rotor (4,4a,4b,14) coupled to the diaphragm, the diaphragm vibrations then being converted into rotary motion via frictional contact at a diaphragm/rotor interface (6b/4,11/14);
- wherein one or more rotors (4a,4b,14) are held in contact with the oscillating surfaces of the diaphragm by magnetic attraction brought about by an electromagnet winding.
An ultrasonic motor as recited in 1 wherein the displacement amplifier diaphragm (6a,6b,13) and the disc (7,11) assembly rotates about the rotor (4a,4b,14).
An ultrasonic motor as claimed in any preceding claim wherein the or each flextensional amplifier diaphragm is dish-shaped with an upset central region.
Dependencies are inferred from the claim text.