US 4,285,676 AGranted

Mechanical belt tensioner construction

AssigneeDyneer Corporation

InventorDerald H. Kraft

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Abstract

A tensioning device for maintaining a predetermined amount of tensioning force on an endless drive belt for a vehicle accessories drive system. A housing is mounted in a fixed position on the vehicle engine adjacent the drive belt. A lever is pivotally mounted on a shaft which is located within the housing and extends generally radially outwardly from the housing and is adapted to move in a belt tensioning direction. A first pair of cylindrical, torsional coil springs is telescopically mounted on the shaft, with the springs being located one on each side of the lever. A second pair of cylindrical, torsional coil springs is telescopically concentrically mounted on the shaft and surrounds the first spring pair. One end of each spring is attached to the housing with the other spring ends being attached to the lever. The spring pairs are placed in torsion and bias the lever in the belt tensioning direction. An idler pulley is mounted on the end of the lever and is moved into tensioning engagement with the drive belt by the torsion springs, or alternately one of the vehicle accessories is mounted on the end of the lever for tensioning the drive belt which is engaged by the accessory pulley. The tensioner construction enables a large tensioning force to be obtained from a relatively small, compact, simple spring arrangement by using three or more torsional springs.

Claims9

Dependent claims

A belt tensioner construction for automatically tensioning an endless belt of the drive system for vehicle accessories, said tensioner construction including:

(a) a housing adapted to be mounted in a fixed position on a vehicle engine adjacent the drive belt;
(b) a shaft mounted within the housing;
(c) lever means pivotally mounted on the shaft and extending generally radially outwardly from the housing;
(d) pulley means mounted on the lever means and engageable with the drive belt for applying a tensioning force on said belt when the lever means is biased in a belt tensioning direction;
(e) first and second cylindrical coil springs telescopically mounted on the shaft in an axially spaced relationship with respect to each other on respective sides of the lever means, each of said coil springs terminating in a pair of ends, with one end of each coil spring being fixed to the housing and the other end of each coil spring being fixed to the lever means so that upon pivotal movement of the lever means in a direction opposite the belt tensioning direction builds up tension in said first and second springs biasing the lever means in the belt tensioning direction;
and
(f) a third cylindrical coil spring having an internal diameter complementary to the outer diameter of the first coil spring telescopically mounted with respect to the shaft and said first spring and concentric thereto, said third spring terminating in a pair of ends with one end being fixed to the housing and the other end being fixed to the lever means so that upon pivotal movement of the lever means in a direction opposite the belt tensioning direction builds up tension in said third spring biasing the lever means in the belt tensioning direction increasing the biasing forces asserted by the first and second coil springs on said lever means.

4 more elements

Dependencies are inferred from the claim text.