Endless belt power transmission systems or components – Positive drive pulley or guide roll – With particular belt
Utility Patent
1998-12-01
2001-01-02
Bucci, David A. (Department: 3682)
Endless belt power transmission systems or components
Positive drive pulley or guide roll
With particular belt
C474S213000
Utility Patent
active
06168543
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a silent chain power transmission device. Such devices are used in automotive transmissions, transfer cases, engine timing systems, and the like. More specifically, the present invention relates to a silent chain power transmission device in which the sprocket teeth have a curved surface that makes contact with a curved surface on the link plate teeth at each point of engagement. The result is an increase in surface area of the engagement between the link plate teeth and the sprocket teeth, which in turn reduces the contact surface pressure and improves the overall durability as compared with conventional silent chain power transmission devices.
Silent chain transmission devices are formed by an arrangement of link plates in lateral and longitudinal directions. The links are interlaced and joined, forming a chain that is used in conjunction with a sprocket. A typical chain is composed of inner links, which contact the teeth of the sprocket to provide power transmission, and guide links, which do not provide power transmission. Guide links are employed to maintain the chain on the center of the sprocket. A row of link plates, arranged in the lateral direction, typically has a number of inner links combined with guide links in the center or at both edges of the row.
Conventional silent chain transmission devices face durability problems. In the conventional device, power is transmitted by the contact of the flat or convex surface of the link plate with the convex surface of the sprocket teeth. Thus, both surfaces experience wear due to high contact surface pressure. As a result, the durability of the power transmission device is decreased. The present invention is directed at solving this problem. It decreases the wear on the link plates and sprocket teeth by increasing the surface area of the contact between them.
SUMMARY OF THE INVENTION
The object of the present invention is to increase the durability of silent chain power transmission devices. The area of contact between the link plate teeth and the sprocket teeth is increased in surface area. This increase is accomplished by curving the surfaces of both the link plate tooth and the sprocket tooth at the location of contact. The link plate teeth and the sprocket teeth thereby cradle into each other. The increase in surface area of the contact location results in lower contact pressure and thus increased durability of the device.
The silent chain and sprocket system that a preferred embodiment of the present invention comprises has multiple link plates joined by pins inserted into apertures in the link plates. Each of the link plates has teeth that are curved, either concavely or convexly, on either their inside flanks or their outside flanks. In addition, the system's sprocket has multiple teeth that have curved surfaces for engagement with the link plates.
U.S. Pat. No. 5,154,674 to Avramidis and Ledvina also teaches curved link plate teeth. Unlike the present invention, however, the '674 patent teaches link plates that are asymmetrical in order to modify the noise pattern of the chain they comprise. In contrast, the present invention teaches symmetrical link plates in order to increase link plate durability.
For a better understanding of the invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings.
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European Search Report dated May 6, 1999 for 98310560.2.
Borg-Warner Automotive K.K.
Bucci David A.
Dziegielewski Greg
Kaness Matthew A.
Sidley & Austin
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