Endless belt power transmission systems or components – Means for adjusting belt tension or for shifting belt,...
Reexamination Certificate
1999-12-23
2002-03-12
Lorence, Richard M. (Department: 3681)
Endless belt power transmission systems or components
Means for adjusting belt tension or for shifting belt,...
C474S111000, C474S140000
Reexamination Certificate
active
06354972
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to the chain tensioner arts. The preferred embodiment of the invention finds particular application in conjunction with a timing chain drive for an automotive engine, and will be described with reference thereto. However, the present invention can also find application with other types of chain drive systems, and in applications other than automotive engines.
With reference to
FIG. 1
, a conventional chain drive system
10
, of the type often used on internal combustion automobile engines for timing purposes, rotates in a clockwise direction as shown by arrow
11
. The chain drive system
10
includes at least a drive sprocket
12
, a driven sprocket
14
, and a chain
16
(e.g. roller chain, inverted tooth chain, etc.) having a number of chain pitches
18
. As known in the art, the chain drive system
10
can include additional sprockets such as idler sprockets, balance shaft sprockets, etc. The chain
16
engages and wraps about sprockets
12
and
14
and has two spans extending between the sprockets, slack strand
20
and taut strand
22
. A central portion of the taut strand
22
may be guided between the driven sprocket
14
and the drive sprocket
12
with a conventional chain guide (not shown). The taut strand
22
of chain
16
is under tension as s shown by arrow
26
.
A conventional blade-type mechanical tensioner assembly
24
applies a tensioning force to the slack strand
20
. The tensioner assembly
24
includes a bracket
28
, typically formed by stamping as a rigid metal bracket, and an elongated shoe sub-assembly
30
pivotally secured to the bracket
28
by a pivot pin
32
. The sub-assembly
30
includes a chain-engaging shoe member
34
, typically injection molded from a plastic resin material that will “creep” under load and elevated temperature, and a blade spring
36
, typically formed from spring steel, incorporated into the shoe member to provide the shoe sub-assembly
30
with the resiliency and rigidity that is necessary to apply the proper amount of tensioning force to the slack strand
20
of chain
16
.
As best shown in
FIGS. 2
a
and
2
b
, the pivot pin
32
includes a flanged portion
32
A having a cylindrical portion
32
B. The bracket
28
includes an aperture
33
that is shaped to mutually conform to and receive the cylindrical portion
32
B. The pivot pin
32
can be affixed to the bracket
28
in any conventional manner such as by resistance welding, press-fitting, swaging, etc. The pivot pin
32
provides a reaction support and pivoting means for the shoe sub-assembly
30
, thus permitting the tensioner to function properly in a firing engine. The pin
32
, as illustrated in
FIGS. 2
b
and
2
c
, does not extend beyond an engine mounting surface
38
of the bracket. However, at least two fasteners
40
A,
40
B (
FIG. 1
) extend past the engine mounting surface
38
to secure the bracket
28
to an engine case or block in order to properly orient the chain-engaging shoe member
34
with respect to the slack strand
20
of the chain
16
.
With many engine designs, the above-described tensioner assembly
24
must be installed within a confined space, thus making it difficult to utilize multiple fasteners to secure the tensioner assembly to the engine. Accordingly, it is considered desirable to provide a new and improved chain tensioner assembly, that meets the above-stated needs and overcomes the foregoing difficulties and others while providing better and more advantageous results.
SUMMARY OF THE INVENTION
In accordance with one aspect of the present invention, a chain tensioner assembly is provided. The chain tensioner assembly includes a bracket having a first surface and a second surface, and a pivot pin secured to the bracket. The pivot pin includes a first portion extending from the first surface and a second portion extending from the second surface. A shoe sub-assembly is pivotally mounted to the pivot pin first portion. The pivot pin second portion is adapted to extend into a bore of an associated engine component in a mounted state of the chain tensioner assembly.
In accordance with another aspect of the present invention, a chain drive system is provided. The chain drive system includes a first sprocket, a second sprocket, a chain adapted to engage the first sprocket and the second sprocket, and a chain tensioner assembly adapted to impart a tensioning force on the chain. The chain tensioner assembly includes a bracket having a first surface and a second surface, and a pivot pin secured to the bracket. The pivot pin includes a first portion extending from the first surface and a second portion extending from the second surface. A shoe subassembly is pivotally mounted to the pivot pin first portion. The pivot pin second portion is adapted to extend into a bore of an associated engine component in a mounted state of the chain tensioner assembly.
In accordance with a further aspect of the present invention, a chain drive system associated with an automobile engine is provided. The chain drive system includes a drive sprocket rotatably mounted to the engine, a driven sprocket rotatably mounted to the engine, a chain engaging the drive sprocket and the driven sprocket, and a chain tensioner assembly that imparts a tensioning force on the chain. The chain tensioner assembly includes a bracket having a first surface and a second surface, and a pivot pin secured to the bracket. The pivot pin includes a first portion extending from the first surface and a second portion extending from the second surface. A shoe sub-assembly is pivotally mounted to the pivot pin first portion. The pivot pin second portion extends into a bore associated with the engine.
In accordance with yet another aspect of the present invention, a method of mounting a chain tensioner assembly to an engine component is disclosed. The chain tensioner assembly includes a bracket having a first surface and a second surface, and a pivot pin secured to the bracket. The pivot pin includes a first portion extending from the first surface and a second portion extending from the second surface. A shoe sub-assembly is pivotally mounted to the pivot pin first portion. The method includes the steps of inserting the pivot pin second portion into a bore associated with the engine component, and securing the bracket to the engine component with a fastener.
One advantage of the present invention is the provision of a chain tensioner assembly that will package in a confined space where two or more fasteners cannot be easily utilized.
Another advantage of the present invention is the provision of a chain tensioner assembly that can be easily and rapidly secured to an engine component such as an engine block during an assembly procedure.
Yet another advantage of the present invention is the provision of a method for mounting a chain tensioner assembly within a confined space associated with an automotive engine component such as an engine block, where it is difficult to utilize a plurality of conventional fasteners to attach the chain tensioner assembly to the engine component.
Still further advantages of the present invention will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description of the preferred embodiment.
REFERENCES:
patent: 4395250 (1983-07-01), King
patent: 4921472 (1990-05-01), Young
patent: 5286234 (1994-02-01), Young
patent: 5425680 (1995-06-01), Young
patent: 5711732 (1998-01-01), Ferenc et al.
patent: 5730674 (1998-03-01), Ott
patent: 5776024 (1998-07-01), White et al.
Cloyes Gear and Products, Inc.
Fay Sharpe Fagan Minnich & McKee LLP
Lewis Tisha O.
Lorence Richard M.
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