Sports implement

• US 20010001770A1
• Filed: 01/12/2001
• Published: 05/24/2001
• Est. Priority Date: 09/29/1995
• Status: Active Grant

• Current Assignee: Cymer Incorporated (ASML Holding NV)
• Original Assignee: Carl Prestia, David Gilbert, Emanuele Bianchini, Farla M. Russo, Jeffrey W. Moore, Jonathan C. Allen, Kenneth B. Lazarus, Robert N. Jacques, Ronald Spangler
• Inventors: Gilbert, David, Allen, Jonathan C., Russo, Farla M., Prestia, Carl, Jacques, Robert N., Bianchini, Emanuele, Spangler, Ronald, Moore, Jeffrey W., Lazarus, Kenneth B.
• Granted Patent: US 6,485,380 B2
• Time in Patent Office: Days
• US Class Current: 473/221
• CPC Class Codes: A63B 53/00 Golf clubs
• CPC Class Codes: A63B 60/00 Details or accessories of golf clubs, bats, rackets or the like
• CPC Class Codes: A63B 60/54 with means for damping vibrations
• CPC Class Codes: A63C 5/075 Vibration dampers vibration dampers per se F16F7/00

Abstract

A golf club includes an electroactive assembly attached to the club and electrically tuned to capture energy from one or more vibrational modes with high efficiency. More generally, a sports implement includes an electroactive element, such as a piezoceramic sheet attached to the implement, and a circuit attached to the electroactive element. The circuit may be a shunt, or may include processing such as amplification and phase control to apply a driving signal which may compensate for strain sensed in the implement, or may simply alter the stiffness to affect performance. The electroactive element is located in a region of high strain to apply damping, and may include plural subassemblies mounted to capture energy in different planes, or to capture an asymmetric strain distribution while maintaining structural symmetry. In a ski the element captures between about one and five percent of the strain energy of the ski. The region of high strain may be found by modeling mechanics of the sports implement, or may be located by empirically mapping the strain distribution which occurs during use of the implement. In other embodiments, the electroactive elements may remove resonances, adapt performance to different situations, or enhance handling or comfort of the implement. Other embodiments include striking implements intended to hit a ball or object in play, such as mallets, bats and tennis racquets, wherein the strain elements may alter the performance, feel or comfort of the implement. The electroactive elements may be configured in sets to capture energy in different modes, and/or energy distributed along different directions.

Claims

1. A sports implement comprising

a body having an extent and including a contact surface which is subject in use to stimulation such that the body vibrates with a distribution of strain energy in said body including a region of strain

an electroactive assembly including an electroactive strain element for transducing electrical energy and mechanical strain energy, said electroactive assembly being attached to said body in said region of strain, and

circuit across said assembly configured to dissipate said electrical energy and damp vibration of the body.

2. A sports implement according to

claim 1

, which is a golf club.

3. A golf club according to

claim 2

, wherein said stimulation excites vibrational modes of said body giving rise to said strain distribution, and said assembly and circuit alter the vibrational characteristics to improve handling of the golf club.

4. A golf club according to

claim 2

, wherein said strain distribution includes an area of high strain and said assembly is attached by a substantially shear free coupling in said area of high strain.

5. A golf club according to

claim 2

, wherein said electroactive assembly is attached on the shaft and away from the contact surface.

6. A golf club according to

claim 2

, wherein the electroactive assembly includes plural regions of separately-electroded piezo material.

7. A golf club according to

claim 6

, wherein the separate regions are configured to damp vibration in different planes.

8. A golf club according to

claim 2

, wherein said circuit is mounted in a sheet assembly.

9. A golf club according to

claim 2

, comprising an LED indicator in electrical communication with said electroactive assembly.

10. A golf club according to

claim 5

, wherein said electroactive strain element is attached to a flat, a raised surface, a face of the head or a feature of the club effective to couple strain out of the club.

11. A golf club according to

claim 2

, wherein the club has a grip defining a mechanical root of the golf club and the electroactive material is located down shaft from the grip.

12. A golf club according to

claim 2

, wherein said circuit is an inductive shunt for dissipating charge generated by strain coupled from said region of strain into said element.

13. A golf club according to

claim 2

, wherein said strain element is embedded in a shaft formed of composite material.

14. A golf club according to

claim 2

, wherein said strain element is attached by a substantially shear free coupling to said body for coupling in-plane strain energy therebetween.

15. A golf club according to

claim 2

, wherein said electroactive assembly is a curved assembly fitted to the club.

16. A golf club according to

claim 15

, wherein said electroactive assembly is a flexible assembly formed as a sheet with relief cuts for conforming to the club.

26. A golf club according to

claim 2

, wherein said assembly includes a layer of packaging material about the strain element, and strain is coupled to said element through said packaging material.

27. A golf club according to

claim 2

, wherein said assembly includes electroactive material configured to damp vibration occurring along plural different axes.

28. A sports implement according to

claim 1

, wherein the region of strain includes planar areas and said electroactive assembly is formed as a sheet conformable to said planar areas.

29. A sports implement according to

claim 1

, which is an implement selected from among a racquet, a baseball bat, a mallet, a javelin, a pole and other hand-held implement.

30. A sports implement according to

claim 1

, wherein the body includes a shaft having said distribution of strain energy, and the shaft extends to a head having said contact surface.

31. A sports implement according to

claim 30

, wherein the electroactive assembly includes a first set of electroactive elements arranged on one side of a bending axis, and a second set of electroactive elements arranged on an opposite side of the bending axis, and said second set is poled oppositely to said first set and connected to a common shunt.

32. A golf club according to

claim 2

, wherein said electroactive strain element is electroceramic.

17. A method of damping a golf club having a shaft, such method comprising

strain-coupling an electroactive assembly to a region of the golf club located on the shaft and away from its striking surface to receive strain energy from the club and produce electrical charge therefrom, and

placing a circuit across the electroactive assembly to shunt the charge and alter strain in said region thereby changing response of the club.

18. The method of

claim 17

, wherein the step of placing a circuit includes shunting opposed poles of said electroactive assembly to dissipate energy received from said region.

19. The method of

claim 18

, wherein said electroactive assembly includes separately-electroded electroactive elements and the step of placing a circuit includes placing separate circuits across subsets of said elements to produce damping.

20. The method of

claim 19

, wherein the step of strain coupling an assembly to receive strain energy includes mounting the assembly near a mechanical root of said club over a region effective to receive strain energy from said implement and produce damping of at least (0.15) percent.

21. The method of

claim 19

, wherein the step of strain coupling the electroactive assembly includes bonding a sheet assembly to the club.

22. A method of making a damped golf club, such method including the steps of

providing a club having body parts including a head and shaft

adding to at least one body part an electroactive assembly including an electroactive strain element extending along the body part so as to efficiently couple strain between said element and said body part, and

shunting charge generated in said strain element at one or more modal frequencies of a vibrational response of the golf club.

23. A method of making a damped golf club according to

claim 22

, wherein the steps of adding an electroactive assembly and shunting charge at one or more modal frequencies includes adding separate regions of electroactive material which are shunted to damp distinct modal frequencies of the golf club.

24. A golf club having an elongated shaft with a ball striking head at one end end and a grip portion opposed thereto, and a damper attached to at least one of said shaft and said head wherein the damper includes

an assembly of at least one piezoelectric element extending in a sheet so that when attached strain is effectively coupled between said club and said assembly, and

a circuit operative to control charge in the assembly and thereby damp vibration of the club.

25. A golf club according to

claim 24

including at least one LED powered by the assembly to indicate damping operation.