Claims
- 1. An electromagnetic actuator comprising:
- a first electromagnet,
- a second electromagnet in spaced relation with respect to said first electromagnet, said first and second electromagnets being controlled by an electrical signal,
- an armature mounted for movement between said first and second electromagnets, an engaged position of said armature being defined when said armature contacts one of said electromagnets with said electrical signal to the contacted electromagnet being turned-off,
- spring structure operatively associated with said armature to bias said armature away from said engaged position thereof,
- a piezoelectric device operatively associated with said armature so that when said armature is in said engaged position and a force of said spring structure is insufficient to move said armature from contact with said contacted electromagnet, said piezoelectric device is constructed and arranged so that upon being energized, said piezoelectric device moves said armature from contact with said contacted electromagnet.
- 2. The electromagnetic actuator according to claim 1, wherein said piezoelectric device comprises plurality of piezoelectric elements defining a stack, said piezoelectric elements expand in length when energized.
- 3. The electromagnetic actuator according to claim 2, wherein one end of said stack is fixed to a surface of a housing containing one of said electromagnets, an opposite end of said stack being coupled to a shaft, said shaft being coupled to said armature.
- 4. The electromagnetic actuator according to claim 2, wherein each of said piezoelectric elements are of disc-shape.
- 5. The electromagnetic actuator according to claim 4, wherein said piezoelectric elements are composed of ceramic.
- 6. The electromagnetic actuator according to claim 1, wherein said spring structure is a coil spring.
- 7. The electromagnetic actuator according to claim 1, including a voltage source to provide said electrical signal to said electromagnets, and wherein said piezoelectric device is constructed and arranged so as to be powered by EMF voltage which is generated when the electrical signal to said contacted electromagnet is turned-off.
- 8. An electromagnetic actuator comprising:
- a first electromagnet including a stator core and a coil operatively associated with said stator core,
- a second electromagnet in spaced relation with respect to said first electromagnet, said second electromagnet having a stator core and a coil operatively associated with said stator core of said second electromagnet, said coils of said first and second electromagnets being controlled by an electrical signal,
- an armature mounted for movement between said first and second electromagnets, an engaged position of said armature being defined when said armature contacts one of said stator cores with the electrical signal to the coil associated with the contacted stator core being turned-off,
- a shaft coupled with said armature for movement therewith,
- spring structure operatively associated with said shaft to bias said armature away from said engaged position thereof, and
- a piezoelectric device operatively associated with said shaft so that when said armature is in said engaged position and a force of said spring structure is insufficient to move said armature from contact with said contacted stator core, said piezoelectric device is constructed and arranged so that upon being energized, said piezoelectric device moves said shaft and thus moves said armature from contact with said contacted stator core.
- 9. The electromagnetic actuator according to claim 8, wherein said piezoelectric device comprises a plurality of piezoelectric elements defining a stack, said piezoelectric elements expand in length when energized.
- 10. The electromagnetic actuator according to claim 9, wherein said shaft extends through at least one of said electromagnets, and said piezoelectric device is coupled to a portion of said shaft which extends beyond an extent of said at least one electromagnet.
- 11. The electromagnetic actuator according to claim 10, wherein said at least one electromagnet is disposed in a housing, said shaft extending through said housing, one end of said stack being fixed to a surface of said housing, an opposite end of said stack being coupled to said portion of said shaft.
- 12. The electromagnetic actuator according to claim 11, further comprising a plate member coupling said opposite end of said stack to said portion of said shaft.
- 13. The electromagnetic actuator according to claim 9, wherein each of said piezoelectric elements are of disc-shape.
- 14. The electromagnetic actuator according to claim 13, wherein said piezoelectric elements are composed of ceramic.
- 15. The electromagnetic actuator according to claim 8, wherein said spring structure is a coil spring.
- 16. The electromagnetic actuator according to claim 8, including a voltage source to Provide said electrical signal to said electromagnets, and wherein said piezoelectric device is constructed and arranged so as to be powered by EMF voltage which is generated when the electrical signal to said contacted electromagnet is turned-off.
- 17. The electromagnetic actuator according to claim 3, wherein said piezoelectric elements are constructed and arranged to expand in a direction of an axis of said shaft to move said shaft and armature along said axis.
- 18. The electromagnetic actuator according to claim 10, wherein said piezoelectric elements are constructed and arranged to expand in a direction of an axis of said shaft to move said shaft and armature along said axis.
- 19. A method of moving an armature from contact with an electromagnet, the method including:
- providing a piezoelectric device operatively associated with the armature; and
- energizing the piezoelectric device to move the armature from contact with the electromagnet.
- 20. A method of moving an armature from contact with an electromagnet, the method including:
- providing a hold current to hold the armature in contact with the electromagnet,
- providing a piezoelectric device operatively associated with the armature,
- discontinuing the hold current to said electromagnet, and
- energizing the piezoelectric device to move said armature from contact with said electromagnet.
Parent Case Info
This application claims the benefit of U.S. Provisional Application 60/088,145, filed Jun. 5, 1998.
US Referenced Citations (14)
Foreign Referenced Citations (1)
Number |
Date |
Country |
197 35 375 |
Aug 1997 |
DEX |