Mechanical tensioner strut with uni-directional friction damping

Patent metadata

Field	Value
Publication number	US-9316292-B2
Application number	US-201514660442-A
Country	US
Kind code	B2
Filing date	Mar 17, 2015
Priority date	Oct 10, 2012
Publication date	Apr 19, 2016
Grant date	Apr 19, 2016

Abstract

A strut including a housing, a plunger within a space in the housing and including a tapered outer circumferential surface, a primary spring engaged with the housing, a wedge element within the space and including a tapered inner circumferential surface engageable with the outer circumferential surface, and a secondary spring engaged with the wedge element and the plunger to urge the plunger in an axial direction. The primary spring urges the plunger in the axial direction with a first force. In a fully extended mode, the plunger is maximally displaced in the axial direction. In a contracted mode, the plunger is displaced in an opposite axial direction in response to application of a second force, sufficiently greater than the first force, on the plunger in the opposite axial direction. When the second force is sufficiently decreased, the plunger displaces with respect to the housing in the axial direction.

First claim

What is claimed is:

1. A mechanical tensioner strut, comprising:
a housing including a first internal space;
a plunger at least partially disposed within the first internal space and including a first outer circumferential surface tapering in a first axial direction;
a primary spring including a first end and a second end engaged with the housing;
a wedge element disposed within the first internal space and including at least one first inner circumferential surface tapering in a second axial direction, opposite the first axial direction, and directly engageable with the first outer circumferential surface; and,
a secondary spring directly engaged with the wedge element and at least a portion of the plunger to urge the at least a portion of the plunger in the second axial direction, wherein:
the secondary spring is located radially outward of the primary spring;
the primary spring extends past the secondary spring in the first and second axial directions;
the primary spring urges the plunger in the second axial direction, with respect to the housing, with a first force;
in a fully extended mode, the plunger is displaced a maximum distance in the second axial direction with respect to the housing;
in a contracted mode, the plunger is displaced a second distance, with respect to the housing, in the first axial direction in response to application of a second force, greater by a first amount than the first force, on the plunger in the first axial direction; and,
when the second force is decreased by a second amount, the plunger is configured to displace with respect to the housing in the second axial direction.

2. The mechanical tensioner strut of claim 1 , wherein the secondary spring is located radially outward of the primary spring.

3. The mechanical tensioner strut of claim 1 , wherein:
the plunger includes:
a nose:
at least partially disposed within the first internal space; and,
including the first outer circumferential surface, a distal end arranged to receive the second force, and a second internal space; and

a slide at least partially disposed within the first and second internal spaces and including:
a third internal space partially enclosing the primary spring;
a first end directly engaged with the primary spring; and,
a second end directly engaged with the wedge element, wherein:
in the fully extended mode, the nose and slide are each displaced respective third maximum distance in the second axial direction with respect to the housing; and,
in the contracted mode, the nose and slide are each displaced respective fourth maximum distances, with respect to the housing in the first axial direction.

4. A method of dampening movement using a mechanical tensioner strut including: a housing including a first internal space; a plunger at least partially disposed within the first internal space and including a first outer circumferential surface tapering in a first axial direction; a primary spring including a first end and a second end engaged with the housing; a wedge element disposed within the first internal space and including at least one first inner circumferential surface tapering in a second axial direction, opposite the first axial direction, and directly engageable with the first outer circumferential surface; and a secondary spring directly, located radially outward of the primary spring, engaged with the wedge element and at least a portion of the plunger, the method comprising:
applying, using the primary spring, a first force to the plunger;
displacing the plunger in the second axial direction with respect to the housing;
urging the at least a portion of the plunger in the second axial direction, with respect to the housing, with the secondary spring;
applying a second force, greater by a first amount than the first force, to the plunger in the first axial direction;
displacing the plunger in the first axial direction with respect to the housing;
decreasing the second force by a second amount;
displacing the plunger with respect to the housing in the second axial direction; and,
maintaining first and second axial ends of the primary spring past the secondary spring in the first and second axial directions, respectively.

5. The method of claim 4 , wherein displacing the plunger in the first axial direction with respect to the housing includes:
generating a first friction force, opposing displacement of the plunger and the wedge element in the first axial direction, between a second inner circumferential surface of the housing and at least one second outer circumferential surface of the wedge element; and,
displacing the wedge element in the first axial direction with respect to the housing.

6. The method of claim 5 , further comprising:
contacting the first outer circumferential surface with the at least one first inner circumferential surface during displacement of the plunger in the first axial direction; and,
urging the at least one second outer circumferential surface radially outward to increase the first friction force.

7. The method of claim 4 , further comprising, when the plunger is displaced in the second axial direction:
generating a first friction force between the first outer circumferential surface and the at least one first inner circumferential surface;
generating a second frictional force between at least one second outer circumferential surface of the wedge element and a second inner circumferential surface of the housing; and,
urging, with the secondary spring, the at least a portion of the plunger in the second axial direction with a third force, wherein the first frictional force is less than the sum of the second frictional force and the third force.

8. The method of claim 7 , further comprising:
displacing, using the secondary spring, the at least a portion of the plunger in the second axial condition with respect to the wedge element; and,
reducing a magnitude of the second frictional force.

9. The method of claim 7 , further comprising:
contacting the first outer circumferential surface with the at least one first inner circumferential surface;
urging the at least one second outer circumferential surface against the second inner circumferential surface with a radial force;
decreasing the second force by the second amount; and,
displacing the at least a portion of the plunger in the second axial condition to reduce a magnitude of the radial force.

10. The method of claim 4 , wherein:
the secondary spring is located radially outward of the primary spring; or,
the secondary spring is at least partially aligned with the primary spring in the first or second axial direction.

11. The method of claim 4 , wherein:
the plunger includes:
a nose:
at least partially disposed within the first internal space; and,
including the first outer circumferential surface, a distal end arranged to receive the second force, and a second internal space; and

a slide at least partially disposed within the first and second internal spaces and including:
a third internal space partially enclosing the primary spring;
a first end directly engaged with the primary spring; and,
a second end directly engaged with the wedge element;

displacing the plunger in the second axial direction with respect to the housing includes displacing the nose and the slide in the second axial direction with respect to the housing; and,
displacing the plunger in the first axial direction with respect to the housing includes displacing the nose and the slide in the first axial direction with respect to the housing.

12. The method of claim 4 , wherein the first outer circumferential surface or the at leas

Assignees

• Schaeffler Technologies Ag

Inventors

• Hewitt Jeffrey
• Botez Lucian
• Berndt Eric

Classifications

• F16H7/0831 Primary

  of the dry friction type · CPC title

• F16H2007/084

  having vibration damping characteristics dependent on the moving direction of the tensioner · CPC title

• F16F13/005

  comprising both a wound spring and a damper, e.g. a friction damper · CPC title

• F16H2007/0806

  Compression coil springs · CPC title

• F16F7/095

  frictional elements brought into engagement by movement along a surface oblique to the axis of the cylinder, e.g. interaction of wedge-shaped elements · CPC title