Endless belt power transmission systems or components – Means for adjusting belt tension or for shifting belt,... – Guide roll mounted for movement of its axis along arcuate...
Reexamination Certificate
2001-02-28
2003-06-10
Charles, Marcus (Department: 3682)
Endless belt power transmission systems or components
Means for adjusting belt tension or for shifting belt,...
Guide roll mounted for movement of its axis along arcuate...
Reexamination Certificate
active
06575860
ABSTRACT:
BACKGROUND
The present invention is directed to a belt tensioner for a transmission belt system, and more specifically, to an improved damper assembly for the belt tensioner and a method for constructing the belt tensioner incorporating the improved damper assembly.
The main purpose of an automatic belt tensioner is to prolong the life of an engine or accessory drive belt. The most typical use for such automatic belt tensioners is on front-end accessory drives in an automobile engine. This drive includes pulley sheaves for each accessory the belt is required to power, such as the air conditioner, water pump, fan and alternator. Each of these accessories requires varying amounts of power at various times during operation. These power variations, or torsionals, create a slackening and tightening situation of each span of the belt. The belt tensioner is utilized to absorb these torsionals through use of an internally mounted torsion spring. Reference can be made to U.S. Pat. Nos. 5,545,095 or 5,803,850 (each of which are incorporated herein by reference) for examples of prior art belt tensioners.
The automatic belt tensioner will include a tension arm pivotally mounted to a base housing or spring case, where the torsion spring is operatively coupled between the tension arm and the base housing so as to force the distal end of the tension arm against the drive belt, and in turn, to provide sufficient tension force on the drive belt as desired. The size of torsional loads experienced by the drive belt is sometimes large enough to significantly move the tension arm away from the belt, causing the tension in the belt to be temporarily reduced. This is not favorable above a certain degree and squealing and squeaking of the belt may result. Therefore, typical belt tensioners incorporate dampening devices to slow the pivotal movement of the tension arm.
SUMMARY
The present invention provides a belt tensioner for a transmission belt system that includes an improved damper assembly; and furthermore, a method for manufacturing such a belt tensioner that includes the improved damper assembly.
A first aspect of the present invention is directed to a belt tensioner for a power transmission belt system that includes (a) a base housing including a pivot shaft extending therefrom; (b) a tension arm pivotally mounted on the pivot shaft at a proximal end thereof, the proximal end of the tension arm including a rub surface and the distal end of the tension arm adapted to contact a power transmission belt; (c) a torsion spring operatively coupled between the base and the tension arm and adapted to bias the distal end of the tension arm against the power transmission belt; and (d) a damper assembly coupled to the housing, the damper assembly including: (1) a body of friction material that includes a friction surface adjacent to and facing the rub surface of the tension arm and (2) a damper spring integral with the body of friction material and biasing the body of friction material and associated friction surface against the rub surface of the tension arm.
In a more detailed embodiment, the damper assembly is substantially disk shaped and coaxially mounted on the pivot shaft. In a further detailed embodiment, the damper spring is an annular metallic spring plate coaxially integrated with a substantially disk-shaped body of friction material. In yet a further detailed embodiment, the spring plate has a generally conical shape and includes a convex side facing toward the rub surface of the tension arm, where the generally conical shape of the spring plate biases the body of friction material axially against the rub surface of the tension arm. In yet a further detailed embodiment, the damper assembly includes an annular flange extending at least partially axially towards the tension arm and encircling an annular shoulder of the tension arm, thereby providing a labyrinth seal between the damper assembly and the tension arm. In yet a further detailed embodiment, the annular flange extends from the body of the friction material.
In an alternative detailed embodiment of the first aspect of the present invention, the body of friction material is molded over the damper spring. In a further detailed embodiment, the body of friction material is a wear-resistant plastic material. In a further detailed embodiment, the body of friction material is substantially disk shaped, and the damper spring is an annular metallic spring plate coaxially molded with the substantially disk-shaped body of friction material and the annular metallic spring plate biases the body of friction materially axially against the rub surface of the tension arm. In a further detailed embodiment, the annular metallic spring plate is coaxially attached to the pivot shaft of the base housing, and the proximal end of the tension arm is retained axially between the damper assembly and the base housing by the coaxially attachment of the annular metallic spring plate and pivot shaft.
In an alternate detailed embodiment of the first aspect of the present invention, the damper assembly is mounted to the base housing, coaxially with the pivot shaft, and includes an annular flange extending at least partially axially towards the tension arm and encircling an annular shoulder of the tension arm, thereby providing a labyrinth seal between the damper assembly and the tension arm. In a further detailed embodiment, the annular flange extends from the body of friction material. In an even further detailed embodiment the annular flange extending from the damper assembly has an inner diameter slightly larger than the outer diameter of the annular shoulder of the tension arm.
A second aspect of the present invention is directed to a belt tensioner for a power transmission belt system that includes: (a) a base housing including a pivot shaft extending therefrom; (b) a tension arm pivotally mounted on the pivot shaft at a proximal end thereof, where the proximal end of the tension arm includes a rub surface and the distal end of the tension arm is adapted to contact a power transmission belt; (c) a torsion spring operatively coupled between the base and the tension arm, and adapted to bias the distal end of the tension arm against the power transmission belt; and (d) a damper assembly coupled to the housing, where the damper assembly includes: (1) an annular spring plate coaxially attached to the pivot shaft of the base housing and (2) a body of friction material having at least a portion positioned axially between the annular spring plate and the rub surface of the tension arm; (e) where the body of friction material includes a friction surface adjacent to and facing the rub surface of the tension arm; and (f) where the annular spring plate biases the body of friction material and associated friction surface against the rub surface of the tension arm and retains the proximal end of the tension arm and the body of friction material axially between the annular spring plate and the base housing.
In a further detailed embodiment of the second aspect of the present invention described above, the body of friction material is annular and is positioned coaxially with the pivot shaft, and includes an annular flange extending at least partially axially toward the tension arm and encircling an annular shoulder of the tension arm, thereby providing a labyrinth seal between the body of friction material and the tension arm. In a further detailed embodiment, the annular flange extending from the damper assembly has an inner diameter that is slightly larger than the outer diameter of the annular shoulder of the tension arm. And in a further detailed embodiment, the body of friction material is molded over the annular spring late.
In an alternate detailed embodiment of the second aspect of the present invention described above, the body of the friction material is molded over the annular spring plate.
In another alternate embodiment of the second aspect of the present invention described above, the body of friction material is substantially annular and coaxially positioned with
Charles Marcus
Dayco Products LLC
Tassone Joseph V.
LandOfFree
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