Endless belt power transmission systems or components – Means for adjusting belt tension or for shifting belt,... – Tension adjuster has surface in sliding contact with belt
Reexamination Certificate
2000-07-31
2003-07-01
Charles, Marcus (Department: 3682)
Endless belt power transmission systems or components
Means for adjusting belt tension or for shifting belt,...
Tension adjuster has surface in sliding contact with belt
C474S140000
Reexamination Certificate
active
06585614
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a guide for a chain drive provided on an engine body.
2. Description of the Related Art
Conventionally, chain drives installed on an engine body having a cylinder block and a cylinder head are classified into two types according to the way of mounting a guide to the engine body.
A first type of conventional chain drive is shown in FIG.
8
A and includes a guide
11
mounted to an engine body so that it extends over a cylinder block
1
and a cylinder head
6
of the engine body. In the chain drive, a chain
9
is trained around a sprocket (crank sprocket)
7
rotatably mounted on the cylinder block
1
and two sprockets (cam sprockets)
8
,
8
rotatably mounted on the cylinder head
6
, and a tensionder device
10
is disposed on the exterior side of a slack run of the chain
9
for applying an appropriate tension to the chain
9
. The guide
11
for the chain drive is disposed on the exterior side of a tension run of the chain
9
for preventing oscillation of the chain
9
while running.
The tensioner device
10
is comprised of a tensioner lever
10
B pivotally connected at one end to a mounting surface of the cylinder block
1
, and a tensioner
10
A for urging a free end portion of the tensioner lever
10
B against the chain
9
. By a biasing force of the tensioner
10
A, a shoe surface of the tensioner lever
10
B is forced against the slack run of the chain
9
so that an appropriate tension is applied to the chain
9
.
The guide
11
has two mounting portions provided near opposite longitudinal ends of the guide
11
and each formed with one circular mounting hole (not show) . A screw
14
is inserted through the mounting hole of one mounting portion (upper mounting portion) and threaded into a threaded hole (not shown) formed in the cylinder head
6
. Similarly, a screw
14
is inserted through the mounting hole of the other mounting portion (lower mounting portion) and threaded into a threaded hole (not shown) formed in the cylinder block
1
. The guide
11
is thus mounted to the engine body by means of the screws
14
.
A second type of conventional chain drive is shown in FIG.
9
A and includes a guide
13
mounted to a cylinder block
4
of an engine body. In the chain drive used on the engine body comprised of the cylinder block
4
and a cylinder head
6
, a chain
9
is trained around a cylinder block side sprocket (crank sprocket)
7
and two cylinder head side sprockets (cam sprockets)
8
,
8
, and a tensionder device
10
is disposed on the exterior side of a slack run of the chain
9
for applying an appropriate tension to the chain
9
. The guide
13
for the chain drive is disposed on the exterior side of a tension run of the chain
9
for preventing oscillation of the chain
9
while running.
The tensioner device
10
is comprised of a tensioner lever
10
B pivotally connected at one end to a mounting surface of the cylinder block
4
, and a tensioner
10
A for urging a free end portion of the tensioner lever
10
B against the chain
9
. By a biasing force of the tensioner
10
A, a shoe surface of the tensioner lever
10
B is forced against the slack run of the chain
9
so that an appropriate tension is applied to the chain
9
.
The guide
13
has two mounting portions provided near opposite longitudinal ends of the guide
13
and each formed with one circular mounting hole (not shown). Two screw
14
are inserted through the respective mounting holes of the upper and lower mounting portions and threaded into threaded holes (not shown) formed in the cylinder block
4
, whereby the guide
13
is mounted to the cylinder block
4
by means of the screws
14
.
In an engine, there is a case where the cubic capacity or displacement of the engine is changed by replacing the cylinder block with another cylinder block having a different height while the cylinder head remains unchanged.
FIG. 8B
shows a right half of the chain drive which is used on an engine body whose cubic capacity has been changed by using a cylinder block
2
having a different height than the cylinder block
1
shown in FIG.
8
A.
As shown in
FIG. 8B
, in the case where the cubic capacity of the engine is changed by using a cylinder block
2
of a different height (larger height) in combination with the existing cylinder head
6
, in order to use the same guide
11
in common, the distance or pitch P
1
between the threaded hole in the cylinder head
6
and a threaded hole in the cylinder block
2
must be made equal to the distance or pitch P
1
between the threaded hole in the cylinder head
6
and the threaded hole in the cylinder block
1
. To this end, the position of the threaded hole formed in the cylinder block
2
is displaced upward from that of the threaded hole in the cylinder block
1
by a distance h which is equal to a difference in height between the cylinder blocks
2
and
1
. There arises a problem that the same working or processing cannot be used for forming threaded holes in more than two cylinder blocks of different sizes (heights).
As shown in
FIG. 8C
, in the case where the cubic capacity of the engine is changed by using a cylinder block
3
of a different height in combination with the existing cylinder head
6
, if the use of the same processing on the cylinder block takes preference over the use of the same guide, a threaded hole in the cylinder block
3
is formed at the same position as the threaded hole in the cylinder block
1
shown in FIG.
8
A. Due to a difference in pitch between the threaded hole of the cylinder head and the threaded hole of the cylinder block, the same guide
11
cannot be used. To deal with this problem, a similar guide
12
must be provided, having two circular mounting holes spaced at the same distance or pitch as the pitch P
2
between the threaded holes in the cylinder block
3
and cylinder head
6
. As a consequence, similar guides of different sizes (lengths) must be provided, tending to cause confusion between them.
FIG. 9B
shows a right half of the chain drive which is installed on an engine body whose cubic capacity has been changed by using a cylinder block
5
having a different height than the cylinder block
4
shown in FIG.
9
A.
The guide
13
shown in
FIG. 9A
has two circular mounting holes (not shown) formed in two mounting portions provided near opposite longitudinal ends of the guide
13
. Two screw
14
are inserted through the respective mounting holes of the upper and lower mounting portions of the guide
13
and threaded into two threaded holes (not shown) both formed in the cylinder block
4
, whereby the guide
13
is attached by the screws
14
to the cylinder block
4
. Accordingly, in the case where the cubic capacity of the engine is changed by replacing the cylinder block
4
with a cylinder block
5
of a different height while the cylinder head
6
remains unchanged, as shown in
FIG. 9B
, the same processing can be used in common such that two threaded holes are formed in the cylinder block
5
at the same position as those formed in the cylinder block shown in FIG.
9
A. Thus, the same guide
13
can be used.
However, the chain drive shown in FIG.
9
A and the chain drive shown in
FIG. 9B
differ from each other in the positional relationship between the guide
13
and an adjacent one of the cylinder head side sprockets (cam sprockets)
8
. More specifically, the distance H
2
(
FIG. 9B
) between the axis of the cam sprocket
8
and an adjacent end (upper end) of the guide
13
is larger than the distance H
1
(
FIG. 9A
) between the axis of the cam sprocket
8
and the adjacent end of the guide
13
. This means that the chain drive shown in FIG.
9
A and the chain drive shown in
FIG. 9B
each have a different chain line or path extending between the cam sprocket
8
and the guide
13
. Thus, the guides
13
shown in
FIGS. 9A and 9B
achieve different oscillation preventing effects with respect to the chain
9
, tending to vary the acoustic and vibration characteristics of the chain drives.
SUMMARY OF TH
Charles Marcus
Dann Dorfman Herrell and Skillman
Skillman Henry H.
Tsubakimoto Chain Co.
LandOfFree
Guide for chain drive does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Guide for chain drive, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Guide for chain drive will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3043934