Piezoelectric latching actuator having an impact receiving projectile

• US 4,672,257 A
• Filed: 01/21/1986
• Issued: 06/09/1987
• Est. Priority Date: 01/21/1985
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Wakamatsu, Kazutoshi, Aihara, Yoshiki, Oota, Takashi, Okihara, Naoto, Uchikawa, Tadao
• Primary Examiner(s): Budd, Mark O.
• Application Number:
  US06/820,603
• Time in Patent Office: 504 Days
• Field of Search: 310/328, 310/330-332, 200/181
• US Class Current: 310/328
• CPC Class Codes: H01H 2057/003 the relay being latched in actuated position by magnet
• CPC Class Codes: H01H 57/00 Electrostrictive relays; Piezoelectric relays

Abstract

Disclosed is a piezoelectric actuator comprising a pair of piezoelectric elements, bistable snap-action means, and projectile means attached to the snap-action means in an impact receiving relationship alternately with the piezoelectric elements. The projectile means has a mass sufficient to acquire an acceleration upon impact from each of the piezoelectric elements to cause the snap-action means to change state. The snap-action means may comprise an elongated bending element squeezed endwise between supports, the projectile means being carried by bending element at a point intermediate its ends.

Claims

1. A piezoelectric actuator comprising:

a pair of elongated piezoelectric elements, each of said elements being secured at one end to a support and being formed of multilayered ceramics for generating a rapidly varying displacement in a longitudinal direction thereof when an electrical potential is applied thereto;

bistable snap-action means; and

projectile means attached to said snap-action means in an impact receiving relationship for alternately engaging an end which is opposite said one end on each one of said piezoelectric elements, said projectile means having a mass which is sufficient to acquire an acceleration responsive to receiving an impact from each of said piezoelectric elements to cause said snap-action means to change state.

2. A piezoelectric actuator as claimed in claim 1, wherein said snap-action means comprises spring means.

3. A piezoelectric actuator as claimed in claim 2, wherein said spring means comprises an elongated bending element squeezed endwise on a support to assume a curve representing a bistable state.

4. A piezoelectric actuator as claimed in claim 1, further comprising hammerhead means attached to each of said piezoelectric elements in an impact transfer relationship from the piezoelectric element to said projectile means.

5. A piezoelectric actuator as claimed in claim 1, wherein said opposite ends of said piezoelectric elements are in an opposed relationship with respect to each other, said projectile means being located between said opposite ends of said piezoelectric elements.

6. A piezoelectric actuator as claimed in claim 3, further comprising a flexible contact arm secured to said elongated bending element for cooperating with a stationary contact in response to the bending element changing state.

7. A piezoelectric actuator as claimed in claim 3, further comprising a pair of flexible contact arms, wherein said elongated bending element is provided with a cross arm for urging said flexible contact arms to cooperate with stationary contacts.

8. A piezoelectric actuator as claimed in claim 3, wherein said projectile means comprises an elongated member extending perpendicularly to said elongated bending element, said elongated member having opposite ends in an impact receiving relationship with said piezoelectric elements respectively, further comprising flexible contact arms engaged with said elongated projectile member for cooperating with stationary contacts in response to said bending element changing state.

9. A piezoelectric actuator as claimed in claim 2, further comprising a first pair of flexible contact arms and a second pair of flexible contact arms, wherein said spring means comprises an elongated bending element squeezed endwise between pivot points which are located intermediate the opposite ends of said elongated bending element, a first hammerhead means fitted to one end of said elongated bending element for alternately urging the flexible contact arms of said first pair and a second hammerhead means fitted to the other end of said elongated bending element for alternately urging the flexible contact arms of said second pair.

10. A piezoelectric actuator as claimed in claim 1, wherein said snap-action means comprises magnetic flux generating means for defining a pair of magnetic poles and a pivotally movable member of magnetic material pivoted at one end thereof so that the free end thereof is movable between said magnetic poles, said projectile means being carried by said pivotally movable member for moving it between said poles upon receiving impact from each of said piezoelectric elements.

11. A piezoelectric actuator as claimed in claim 10, wherein said flux generating means comprises a pair of permanent magnets.

12. A piezoelectric actuator as claimed in claim 10, wherein said flux generating means comprises a permanent magnet and yoke means connected to said magnet to define said poles.

13. A piezoelectric actuator as claimed in claim 2, wherein said spring means comprises a pivotally swingable member pivoted at one end thereof carrying said projectile means and a spring connecting said pivotally movable member to a support so that said pivotally swingable member can be tilted to either side thereof by said spring to allow said projectile means to establish said impact receiving relationship with each of said piezoelectric elements.

14. A piezoelectric actuator as claimed in claim 2, wherein said spring means comprises a cantilever spring carrying said projectile means, said cantilever spring having a leaf spring integrally formed therewith and extending therefrom to engage with a stationary support to cause said cantilever spring to take the shape of a curve.

15. A piezoelectric actuator comprising:

a pair of piezoelectric elements, said piezoelectric elements being located parallel to each other for generating an impact in one direction, further comprising a pair of lever means for altering the direction of impact generated by each of said piezoelectric elements;

bistable snap-action means; and

projectile means attached to said snap-action means in an impact receiving relationship for altermately engaging said piezoelectric elements, said projectile means having a mass which is sufficient to acquire an acceleration upon impact from each of said piezoelectric elements to cause said snap-action means to change state.

16. A piezoelectric actuator comprising:

a pair of piezoelectric elements;

bistable snap-action spring means having an elongated bending element squeezed endwise on a support to assume a curve representing a bistable state, a pair of flexible contact arms, wherein said elongated bending element is provided with a pair of limbs extending from one end portion of said elongated bending element, the free ends of said limbs having lateral extensions for urging said flexible contact arms to cooperate with stationary contacts; and

projectile means attached to said snap-action means in an impact receiving relationship for altermately engaging said piezoelectric elements, said projectile means having a mass which is sufficient to acquire an acceleration upon impact from each of said piezoelectric elements to cause said snap-action means to change state.

17. A piezoelectric actuator comprising:

a pair of piezoelectric elements;

bistable snap-action spring means comprising a pair of first and second elongated bending elements, each of said bending elements being squeezed endwise on a support, said elongated bending elements being spaced from each other and located between said piezoelectric elements; and

projectile means attached to said snap-action means in an impact receiving relationship for alternately engaging said piezoelectric elements, said projectile means having a mass which is sufficient to acquire an acceleration upon impact from each of said piezoelectric elements to cause said snap-action means to change state, said projectile means further comprising an elongated projectile member attached at opposite ends to said first and second elongated bending elements, and a pair of impact receiving portions respectively attached to said bending elements in an impact receiving relationship with said piezoelectric elements, said projectile means still further comprising a plurality of flexible contact arms extending to right angles to and engaging said elongated projectile member for cooperating with stationary contacts in response to said bending element changing state.

18. A piezoelectric actuator comprising:

a pair of piezoelectric elements;

bistable snap-action spring means, said spring means comprises an elongated bending element squeezed endwise on a support to assume a curve representing a bistable state; and

projectile means attached to said snap-action means in an impact receiving relationship for alternately engaging said piezoelectric elements, said projectile means having a mass which is sufficient to acquire an acceleration upon impact from each of said piezoelectric elements to cause said snap-action means to change state, a pair of flexible contact arm located one on each side of said elongated bending element, each of said flexible contact arms having an impact transfer menas in an impact receiving relationship with an associated one of said piezoelectric elements and in impact transfer relationship with said projectile means.

19. A relay comprising:

a pair of piezoelectric elements, each of said elements being secured at one end to a support and being formed of multilayered ceramics for generating a rapidly varying displacement in a longitudinal direction thereof in response to an electrical pulse applied thereto;

bistable snap-action means;

projectile means attached to said snap-action means for movement therewith and located in an impact receiving relationship for alternately engaging an end opposite said one end of each one of said piezoelectric elements, said projectile means having a mass which is sufficient to acquire an acceleration upon receiving an impact from each of said piezoelectric elements to cause said snap-action means to change state; and

a flexible contact arm carrying a moving contact for cooperating with a stationary contact in response to said snap-action device changing state.

20. A relay comprising:

a pair of elongated piezoelectric elements, each of said elements being secured at one end to a support and being formed of multilayered ceramics for generating a rapidly varying displacement in a longitudinal direction thereof in response to an electrical pulse applied thereto;

a bistable bending element squeezed endwise;

an elongated projectile extending perpendicularly to and being attached to said bending element for movement therewith, said projectile having opposite ends located in an impact receiving relationship for alternately engaging an end opposite said one end of each one of said piezoelectric elements, said projectile having a mass which is sufficient to acquire an acceleration upon receiving an impact from each of said piezoelectric elements to cause said bending element to change state; and

a plurality of flexible arms carrying moving contacts for cooperating with associated stationary contacts in response to said bending element changing state.