Oscillating crystal force transducer and method of making

• US 4,940,915 A
• Filed: 11/02/1988
• Issued: 07/10/1990
• Est. Priority Date: 03/14/1988
• Status: Expired due to Fees

• Current Assignee: Robertshaw Controls Company (Schneider Electric SE)
• Original Assignee: Robertshaw Controls Company (Schneider Electric SE)
• Inventors: Scott, Douglas R., Goddard, Peggy L., Wagner, Joseph P.
• Primary Examiner(s): Budd, Mark O.
• Application Number:
  US07/266,405
• Time in Patent Office: 615 Days
• Field of Search: 310/351-353, 310/354-356, 310/338, 310/339, 310/328, 73/774, 73/775, 73/778, 73/781, 73/514, 73/517 AV, 73/760, 73/763, 73/700, 73/703, 73/754, 73/DIG. 4
• US Class Current: 310/338
• CPC Class Codes: G01L 1/162 using piezoelectric resonators

Abstract

An oscillating crystal force transducer and method of making the same are provided, the transducer comprising support structure, a plate-shaped piezo-electric crystal having opposed sides and a peripheral edge extending between the opposed sides, and two seating members carried by the support structure and respectively engaging the peripheral edge of the crystal and arranged to apply a force to the crystal along a line extending through the crystal from one of the seating members to the other of the seating members, the support structure comprising a looped spring member having opposed ends spaced from each other to define the mouth of the looped spring member and respectively carrying the seating members whereby the crystal is disposed in the mouth of the looped spring member between the seating members thereof.

Claims

1. In an oscillating crystal force transducer comprising support means, a substantially flat plate-shaped piezo-electric crystal having opposed flat sides and a relatively narrow peripheral edge means extending between said opposed sides, and two seating members carried by said support means and respectively engaging said peripheral edge means of said crystal and arranged to apply a force to said crystal along a line extending through said crystal from one of said seating members to the other of said seating members, the improvement wherein said support means comprises a looped substantially flat ribbon-like spring member having a longitudinal axis disposed in a generally U-shape and having opposed free end means spaced from each other to define the mouth of said looped spring member and respectively carrying said seating members whereby said crystal is disposed in said mouth of said looped spring member between said seating members thereof in a manner to be substantially coplanar with said longitudinal axis of said spring member.

2. A transducer as set forth in claim 1 wherein each said seating member has a ball-like surface engaging said peripheral edge means of said crystal.

3. A transducer as set forth in claim 2 wherein said peripheral edge means of said crystal has opposed substantially flat parallel sections respectively being engaged by said ball-like surface of said seating members.

4. A transducer as set forth in claim 1 wherein each said seating member has a generally chisel-shaped surface engaging said peripheral edge means of said crystal.

5. A transducer as set forth in claim 4 wherein said peripheral edge means of said crystal has opposed substantially flat parallel sections respectively being engaged by said chisel-shaped surfaces of said seating members, each said chisel-shaped surface having the long dimension thereof disposed substantially transverse to the long dimension of its respective flat section of said peripheral edge means of said crystal.

6. A transducer as set forth in claim 1 wherein said looped spring member has two openings respectively extending through said opposed end means thereof, said seating members being respectively mounted in said openings.

7. A transducer as set forth in claim 6 wherein each said seating member has opposed ends and a medial portion intermediate said opposed ends thereof, each said seating member having its said medial portion disposed in its respective opening and its said opposed ends respectively extending outboard of its respective end means of said looped spring member.

8. A transducer as set forth in claim 7 wherein each said seating member has one of its said opposed ends facing toward said one opposed end of said other seating member, said one opposed ends of said seating members engaging said peripheral edge means of said crystal.

9. A transducer as set forth in claim 8 wherein said crystal has said peripheral edge means embedded into said one opposed ends of said seating members.

10. A transducer as set forth in claim 8 wherein said support means comprises a relative rigid frame member having a surface means provided with an indentation therein, one of said seating members having the other of said opposed ends thereof disposed in said indentation whereby said indentation locates said looped spring member in said transducer.

11. A transducer as set forth in claim 10 wherein said transducer has a movable wall means carried by said support means and engaging the other of said opposed ends of the other of said seating members whereby said movable wall means increases the force acting along said line through said crystal as said movable wall means moves in a direction toward said crystal and decreases said force as said movable wall means moves in a direction away from said crystal.

12. A transducer as set forth in claim 11 wherein said movable wall means comprises a flexible diaphragm.

13. A transducer as set forth in claim 11 wherein each said seating member comprises a ball.

14. A transducer as set forth in claim 11 wherein each said seating member has said one opposed end thereof being generally chisel-shaped and has the other opposed end thereof being generally conically shaped.

15. A transducer as set forth in claim 1 wherein said spring member is formed of metallic material.

16. A transducer as set forth in claim 15 wherein said spring member is formed of high carbon steel.

17. A transducer as set forth in claim 15 wherein said spring member is formed of stainless steel.