Torsion springs with changeable stiffness

Patent metadata

Field	Value
Publication number	US-9822835-B1
Application number	US-201514627550-A
Country	US
Kind code	B1
Filing date	Feb 20, 2015
Priority date	Feb 20, 2014
Publication date	Nov 21, 2017
Grant date	Nov 21, 2017

Abstract

In at least one embodiment, a rotational spring is provided with adjustable stiffness and includes at least one beam arranged about an axis between an input tuning port and an output port, wherein the input tuning port is configured to change an effective bending length of at least one beam so as to change a shear stiffness with respect to the input tuning port and the output port.

First claim

What is claimed is:

1. A rotational spring with adjustable stiffness, comprising at least one beam comprising a negative stiffness member arranged about an axis extending between an input tuning port and an output port, wherein the input tuning port is configured to change an effective bending length of the at least one beam so as to change a shear stiffness with respect to the input tuning port and the output port and so as to change an effective length of the negative stiffness member so as to change a buckling mode of the negative stiffness member.

2. The rotational spring of claim 1 , wherein the rotational spring is configured so that the input tuning port is capable of changing an effective length of the negative stiffness member by compression of the negative stiffness member to change a buckling mode of the negative stiffness member.

3. The rotational spring of claim 2 , further comprising a positive stiffness coupled in parallel with the negative stiffness member.

4. The rotational spring of claim 1 , wherein the rotational spring comprises:
a) at least one base comprising a plurality of elongated beams spaced apart and in a generally longitudinal configuration about the axis;
b) a rotatable section comprising a plurality of elongated beams spaced apart and configured in a generally longitudinal configuration about the axis, the plurality of elongated beams of the rotatable section being at least partially interdigitated between the plurality of elongated beams of the at least one base; and
c) wherein a relative distance between the at least one base and the rotatable section is adjustable such that adjusting the relative distance between the at least on base and the rotatable section changes an effective bending length of at least one of: (1) the plurality of elongated beams of the at least one base; or (2) the plurality of elongated beams of the rotatable section.

5. The rotational spring of claim 4 further comprising an alignment shaft coupling the at least one base and the rotatable section.

6. The rotational spring of claim 4 further comprising at least one torsional spring coupled between the at least one base and the rotatable section, the torsional spring being mounted about at least one of: (a) the plurality of elongated beams of the base, or (b) the plurality of elongated beams of the rotatable section.

7. The rotational spring of claim 4 further comprising:
a) wherein the at least one base comprises a first base and a second base comprising:
(i) wherein the first base comprises a plurality of first beams extending laterally from the first base; and
(ii) wherein the second base comprise a plurality of second beams extending laterally from the second base;

b) wherein the rotatable section is located between the first base and the second base, the central section comprising a plurality of beams at least partially interdigitated between the plurality of first beams on a first side and at least partially interdigitated between the plurality of second beams on a second side; and
c) wherein the first base and the second base being separated by a relative distance such that adjusting the relative distance between the first base and the second base changes an effective bending length of at least one of: (1) the plurality of first beams; (2) the plurality of second beams; or (3) the plurality of beams of the rotatable section.

8. The rotational spring of claim 1 , wherein the rotation spring comprises:
a) at least one base;
b) a rotatable section comprising a plurality of beams configured in a generally cylindrical arrangement; and
c) an adjustable slider apparatus extending through the at least one base and slidably engaging the plurality of rotatable section beams to define the bending length of the plurality of beams.

9. The rotational spring of claim 1 , wherein the rotational spring comprises:
a) at least one base;
b) a rotatable section comprising the output port;
c) the negative stiffness member being mounted between the rotatable section and the at least one base; and
d) the input tuning port comprising an adjustment means to adjust an effective bending length of the negative stiffness member.

10. The rotational spring of claim 9 , wherein the rotational spring comprises:
a) a shaft extending between the at least one base and the rotatable section retained thereon; and
b) the adjustment means extending through the at least one base to apply the compression load on the negative stiffness member.

11. The rotational spring of claim 10 further comprising a positive stiffness spring coupled between the at least one base and the rotatable section in parallel with the at least one negative stiffness member.

12. The rotational spring of claim 9 , comprising:
a) wherein the at least one base comprises a first base and a second base;
b) wherein the rotatable section is located between the first base and the second base;
c) wherein the at least one beam comprises a plurality of first negative stiffness bending beams extending between the rotatable section and the first base;
d) a positive stiffness spring coupled between the rotatable section and at least one of the first base or the second base.

13. The rotational spring of claim 9 further comprising:
a) wherein the base comprises a base plate;
b) wherein the a rotatable section comprising a rotatable plate opposing the base plate;
c) wherein the at least one beam comprises a plurality of radially oriented negative stiffness members each comprising a negative stiffness beam and a wedge portion, the plurality of radially oriented negative stiffness members each having an end distal from the wedge portion slidably engaging one of the base or the rotatable section; and
d) one of the base plate or the rotatable plate further comprising wedge portions opposing a corresponding wedge portion of one of the plurality of radially oriented negative stiffness members such that adjusting a relative distance between the base plate and the rotatable plate causes the wedge portions of the plurality of radially oriented negative stiffness members to slidably engage opposing wedge portions of the one of the first base plate or the rotatable plate so as to change an effective bending length of the plurality of radially oriented negative stiffness beams.

14. The rotational spring of claim 13 , wherein the base plate and the rotatable plate are coupled via an alignment shaft extending between the first base plate and the rotatable plate.

15. The rotational spring of claim 13 , wherein the base plate is adjustable with respect to the base.

16. The rotational spring of claim 13 , wherein the base is adjustable with respect to a second base, the second base comprising a second base plate, and wherein the rotatable section further comprises a second rotatable plate opposing the second base plate.

17. The rotational spring of claim 13 , wherein the wedge portions of either the radially oriented negative stiffness members or the wedge portions opposing the wedge portion of the radially oriented negative stiffness member further comprise at least one wedge guide.

18. The rotational spring of claim 1 , further comprising a positive stiffness spring coupled in parallel with the negative stiffness member.

19. A rotational spring with adjustable stiffness, comprising at least one beam arranged about an axis extending between an input tuning port and an output port, wherein the input tuning port is configured to change an effective bending length of the at least one beam so as

Assignees

• Hrl Lab Llc

Inventors

• Keefe Andrew C
• Mcknight Geoffrey P
• Smith Sloan P
• Churchill Christopher B

Classifications

• F16F1/145 Primary

  with means for modifying the spring characteristics (fluid regulation of torsion spring characteristics in vehicle suspensions B60G17/0277) · CPC title

• F16F3/02

  with springs made of steel or of other material having low internal friction · CPC title

• F16F2228/063

  Negative stiffness · CPC title