Stock material or miscellaneous articles – Composite – Of polyamide
Reexamination Certificate
2000-11-10
2002-08-06
Hampton-Hightower, P. (Department: 1711)
Stock material or miscellaneous articles
Composite
Of polyamide
C428S221000, C428S411100, C428S476300
Reexamination Certificate
active
06428899
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a shoe for a tensioner device and chain guide used to prevent vibrations of a timing chain (roller chain, silent chain, etc.) that is used in a timing drive (cam shaft drive, balancer drive, injection drive, etc.) of an automobile engine.
2. Related Art
A timing chain used in a timing drive of an automobile engine is associated with a tensioner device disposed on the outside of a slack run of the chain for removing a looseness or slack of the chain, and a chain guide disposed along a tension run of the chain. for preventing a run out of the chain during traveling.
FIG. 2
is a front view illustrating one example of a timing drive of an automobile engine on which such a tensioner device and a chain guide are mounted, and
FIG. 3
is a front view illustrating another example of the same.
The timing drive of the automobile engine as shown in
FIG. 2
will be explained. A first chain
3
is hung over a driving sprocket
1
fixed to a crankshaft of the engine and an intermediate sprocket
2
, and a second chain
6
is hung over the intermediate sprocket
2
and driven sprockets
4
,
5
each fixed to one of camshafts. Thus, a rotation of the crankshaft is transmitted from the driving sprocket
1
to the intermediate sprocket
2
through the first chain
3
, and a rotation of the intermediate sprocket
2
is transmitted to the driven sprockets
4
,
5
through the second chain
6
, whereby each of the camshafts is driven to rotate.
A first tensioner device
7
to remove a looseness or slack of the first chain
3
is disposed on the outside of a slack run of the first chain
3
. The first tensioner device
7
includes a tensioner
8
and a lever
9
. The lever
9
includes a base
9
A and a shoe
9
B attached to the base
9
A. A proximal end of the lever
9
is pivotally connected to an engine block not illustrated, and the front end of a plunger
8
A of the tensioner
8
pressures the lever
9
on a backside near the front end thereof. Thereby, the shoe
9
B of the lever
9
is held in sliding contact with a traveling face of the first chain
3
so as to apply a tension to the first chain
3
, thereby eliminating a slack of the first chain
3
.
A chain guide
10
to prevent a run out of the first chain
3
during traveling is disposed along a tension run of the first chain
3
The chain guide
10
includes a frame body
10
A of the chain guide
10
and a shoe (not illustrated) that slides on the traveling face of the first chain
3
. The chain guide
10
is also attached to the engine block not illustrated. The shoe of the chain guide
10
is in sliding contact with the traveling face of the first chain
3
so as to prevent a run out of the first chain
3
during traveling.
Further, a second tensioner device
11
to remove a slack of the second chain
6
is disposed on the outside of a slack run of the second chain
6
. In the second tensioner device
11
, a shoe
11
C is attached on the front end of a plunger
11
A through a base
11
B, and the shoe
11
C is urged by the plunger
11
A in the thrust direction. Thereby, the shoe
11
C is in sliding contact with the traveling face of the second chain
6
so as to apply a tension to the second chain
6
, thereby eliminating a slack of the second chain
6
.
Next, the timing drive of the automobile engine as shown in
FIG. 3
will be explained. A chain
7
is hung over the driving sprocket
1
fixed to the crankshaft of the engine and the driven sprockets
4
,
5
each fixed to one of the cam shafts. Thus, a rotation of the crankshaft is transmitted from the driving sprocket
1
to the driven sprockets
4
,
5
through the chain
7
, whereby each of the camshafts is driven to rotate.
A first tensioner device
12
to remove a looseness or slack of the chain
7
is disposed on the outside of a slack run of the chain
7
. The tensioner device
12
includes a tensioner
13
and a lever
14
. The lever
14
includes a base
14
A and a shoe
14
B attached to the base
14
A. A proximal end of the lever
14
is pivotally connected to an engine block not illustrated, and the front end of a plunger
13
A of the tensioner
13
pressures the lever
14
on a backside near the front end thereof. Thus, the shoe
14
B of the lever
14
is held in sliding contact with a traveling face of the chain
7
so as to apply a tension to the chain
7
, thereby eliminating a slack of the chain
7
.
A chain guide
15
to prevent a run out of the chain
7
during traveling is disposed along a tension run of the chain
7
. The chain guide
15
includes a frame body
15
A of the chain guide
15
and a shoe (not illustrated) that slides on the traveling face of the chain
7
. The chain guide
15
is also attached to the engine block not illustrated. The shoe of the chain guide
15
is in sliding engagement with the traveling face of the chain
7
to thereby prevent a run out of the chain
7
during traveling.
Here, in the foregoing shoe for the tensioner device and chain guide, conventionally, a heat resistant synthetic rubber has been used.
However, an automobile engine normally operates under a condition that is totally different from a common working condition. For example, the speed of the chain being used in combination with the shoe is very high, and the pressure to the shoe is also high. Also, the atmosphere contains oil, and the temperature of the oil rises to approximately 140° C. at maximum. Accordingly, use of the heat resistant synthetic rubber as a shoe for a tensioner device and chain guide in an automobile engine gives rise to the following problems.
The heat resistant synthetic rubber has a high frictional resistance because of a high coefficient of friction. Therefore, the loss in operation becomes increased to thereby decrease the fuel efficiency.
The heat resistant synthetic rubber raises the hardness when a thermal stress is given. Especially in a high temperature, the vulcanization progresses on the surface of the heat resistant synthetic rubber, and the hardness rises. There occurs a breakage or a peeling due to the hardening. And, the chain is likely to become worn by the hardening. As a result, the life of the chain, or the life of the engine becomes shortened.
The heat resistant synthetic rubber does not have a very high degree of freedom in the shape, and the designing such as avoiding interfering objects, etc., becomes difficult to perform. This leads to a limited degree of freedom in engine layout.
The heat resistant synthetic rubber has a poor workability, and the total cost becomes increased as well. A preliminary treatment is needed for a base (aluminum alloy, iron, etc.) on which the heat resistant synthetic rubber is applied, and moreover the adhesion and vulcanization processes are necessary. The adhesion of the aluminum alloy to the heat resistant synthetic rubber is not easy to carry out, and the workability is not good. The processing cost of the heat resistant synthetic rubber itself and the processing cost of the base material are increased. In addition, the stock is prolonged because the shoe and the base are produced in the individual processes, and the delivery is also prolonged. Furthermore, the total weight is increased, consequently the total weight of the engine is increased, and the fuel efficiency is lowered.
SUMMARY OF THE INVENTION
Accordingly, the invention intends to solve the conventional problems as mentioned above, and provides a shoe that excels in the wear resistance, slidability, impact resistance, heat resistance, and oil resistance, has a high degree of freedom in the shape, and excels in the workability.
In view of the foregoing object, a shoe for a tensioner device and chain guide according to the invention comprises a resin mold product of a polyamide 66 or a polyamide 46 having a relative viscosity more than 100 (90% formic add method), the resin molded product having a skin layer including a non-spheruite area less than 100 &mgr;m in thickness.
With the use of a resin mold product of a polyamide 66 or a polyamide 46 ha
Fujiwara Toru
Ogawa Takeshi
Dann Dorfman Herrell and Skillman, P.C.
Hampton-Hightower P.
Skillman Henry H.
Tsubakimoto Chain Co.
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