Belt tensioner utilizing asymmetric motion control
A belt tensioner includes a support housing at least in part defining a spring cavity and an arm pivotally attached to the support housing. A spring is located in the spring cavity and is operatively connected to the arm and the support housing to bias the arm about a pivot axis toward an unloaded position relative to the support housing. A damping member includes a hub and deflectable, force-applying elements that are connected to and spaced apart about a periphery of the hub. The force-applying elements are biased toward a contact surface of the arm to apply a frictional force between the contact surface and the force-applying elements to impede rotation of the arm relative to the support housing.
1. A belt tensioner comprising:
a support housing at least in part defining a spring cavity;
an arm pivotally attached to the support housing;
a spring located in the spring cavity and operatively connected to the arm and the support housing to bias the arm about a pivot axis toward an unloaded position relative to the support housing; and
a damping member comprising a hub and deflectable, force-applying elements that are connected to and spaced apart about a periphery of the hub, the force-applying elements being biased toward a contact surface of the arm to apply a frictional force between the contact surface and the force-applying elements to impede rotation of the arm relative to the support housing;
wherein at least one of the force-applying elements is an elastically deflectable leaf spring that is self-biased against the contact surface of the arm.
2. The belt tensioner of claim 1 , wherein the damping member provides asymmetric damping of the arm that depends on a direction of arm rotation relative to the support housing.
3. The belt tensioner of claim 1 , wherein the force-applying elements are formed of material forming the hub.
4. The belt tensioner of claim 1 , wherein the force-applying elements are formed separate from the hub and attached thereto.
5. The belt tensioner of claim 1 further comprising a friction material affixed to the force-applying elements, the friction material being in contact with the contact surface of the arm.
6. The belt tensioner of claim 1 further comprising a biasing member that biases the force-applying element toward the contact surface of the arm.
7. The belt tensioner of claim 1 , wherein the force-applying elements include a free end and an opposite end fixed to the hub to define a respective pivot location.
8. The belt tensioner of claim 7 , wherein the free ends of the force-applying elements are spaced substantially equidistant from each other about the periphery of the hub.
9. The belt tensioner of claim 1 , wherein the force-applying elements are deflected toward the pivot axis of the arm relative to the hub.
10. A belt tensioner comprising:
a support housing at least in part defining a spring cavity;
an arm pivotally attached to the support housing;
a spring located in the spring cavity and operatively connected to the arm and the support housing to bias the arm about a pivot axis toward an unloaded position relative to the support housing; and
a damping member comprising an annular hub having a discontinuous shoulder extending downward therefrom, the discontinuous shoulder comprising an array of force-applying elements extending out from the shoulder, the force-applying elements being a leaf spring having a free end biased toward a contact surface of the arm such that a friction surface of the force-applying elements contact the contact surface to impede rotation of the arm relative of the support housing.
11. The belt tensioner of claim 10 , wherein the damping member provides asymmetric damping of the arm that depends on a direction of arm rotation relative to the support housing.
12. The belt tensioner of claim 10 , wherein the force-applying elements are formed of material forming the annular hub.
13. The belt tensioner of claim 10 , wherein the force-applying elements are formed separate from the hub and attached thereto.
14. The belt tensioner of claim 10 further comprising a friction material affixed to the force-applying elements, the friction material being in contact with the contact surface of the arm.
15. The belt tensioner of claim 10 further comprising a biasing member that biases the free end of the force-applying element toward the contact surface of the arm.
16. The belt tensioner of claim 10 , wherein the force-applying elements have an end opposite the free end that is fixed to the hub to define a respective pivot location.
17. The belt tensioner of claim 16 , wherein the force-applying elements are deflected at their respective pivot location toward the pivot axis of the pivot arm.
18. The belt tensioner of claim 16 , wherein the free ends of the force-applying elements are spaced substantially equidistant from each other about the periphery of the annular hub.
19. A method of forming a belt tensioner that utilizes asymmetric motion control and includes a support housing at least in part defining a spring cavity, an arm pivotally attached to the support housing and a spring located in the spring cavity and operatively connected to the arm and the support housing to bias the arm about a pivot axis toward an unloaded position relative to the support housing, the method comprising:
locating a damping member within a compartment of the arm, the damping member comprising an annular hub and deflectable, force-applying elements that are connected to and spaced apart about a periphery of the annular hub, the force-applying elements being biased toward a contact surface of the arm to apply a frictional force between the contact surface and the force-applying elements to impede rotation of the arm relative to the support housing;
wherein at least one of the force-applying elements is an elastically deflectable leaf spring that is self-biased against the contact surface of the arm; and
fixing an angular position of the damping member relative to the support housing.
20. The method of claim 19 , wherein the force-applying elements are biased in a radial direction toward the contact surface that is substantially perpendicular to the pivot axis of the pivot arm.
21. The method of claim 19 further comprising affixing a friction material to a surface of the force-applying elements, the friction material contacting the contact surface.
22. The method of claim 19 further comprising connecting the force-applying elements to the hub.
23. The method of claim 19 further comprising integrally forming the force-applying elements of material forming the hub.
24. The method of claim 19 further comprising biasing the force-applying elements toward the contact surface using a biasing element.
25. The method of claim 19 further comprising deflecting the force-applying elements in a radial direction toward the pivot axis of the pivot arm.