Chain transmission assembly

Details Chain transmission assembly Chain transmission assembly

2001-01-26

2003-12-02

Joyce, William C (Department: 3682)

Endless belt power transmission systems or components

Positive drive pulley or guide roll

Having nonmetallic component

C474S156000, C474S160000

Reexamination Certificate

active

06656072

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a chain transmission assembly suited to suppressing the occurrence of noise and making an assembly light in weight.
2. Description of Background Art
The following is a description of the meshing of sprocket teeth and rollers of a roller chain for a chain transmission assembly where a roller chain is wrapped around a sprocket. FIG.
8
(
a
) to FIG.
8
(
c
) are explanatory views showing the operation in the state where a related sprocket and roller chain mesh.
In FIG.
8
(
a
), a sprocket
100
, with a center of rotation
101
of the sprocket
100
, includes teeth
102
. . . (where . . . shows a plurality of items, with the same being the case hereafter) of the sprocket
100
, teeth bottoms
103
. . . of the of the sprocket
100
, roll chain link plates
104
shown by an imaginary line (only one shown), roller chain rollers
105
and
106
, and centers of rotation
107
and
108
of the rollers
105
and
106
. In FIG.
8
(
a
), the teeth bottoms
103
of the sprockets
100
are positioned just above the centers of rotation
101
and the rollers
105
mesh with the teeth bottoms
103
.
In FIG.
8
(
b
), when the sprockets
100
rotate by an angle of &thgr;
1
in an counterclockwise direction from the state in FIG.
8
(
a
), the rollers
105
move while remaining meshed with the teeth bottoms
103
of the sprocket
100
and the centers of rotation
107
of the rollers
105
fall by just a distance ∝
1
from the position of FIG.
8
(
a
).
At this time, the rollers
105
and
106
move in an integral manner so that the roller chain goes from being loose to being tense, and the center of rotation of the roller
106
falls just by a distance ∝
1
together with the dropping of the roller
105
.
In FIG.
8
(
c
), the sprocket
100
rotates further in the counter-clockwise direction so that when the sprocket
100
rotates by an angle &thgr;
2
from the state shown in FIG.
8
(
a
), in addition to the rollers
105
and the teeth bottoms
103
of the sprocket
100
meshing, the rollers
106
meshes with the teeth bottoms
103
.
The teeth bottoms
103
collide with the rollers
106
at this time so that a noise therefore occurs due to these collisions.
In this case, the centers of rotation
107
and
108
of the rollers
105
and
106
fall just by ∝
2
from the position of FIG.
8
(
a
), and the distance between the center of rotation
101
of the sprocket
100
and the centers of rotation
107
and
108
of the rollers
105
and
106
becomes R cos &thgr;
2
. The wrapping radius of the roller chain in this case is R cos &thgr;
2
, and an amount of vibration ∝
2
of the roller chain in a vertical direction ∝
2
is 2=R-R cos &thgr;
2
.
In the above, when a roller chain meshes with the sprocket
100
, noise is generated by the teeth bottoms
103
of the sprocket
100
and by the rollers
106
and the wrapping radius of the roller chain changes from R cos &thgr;
2
to R. The vibration of the roller chain is therefore substantial, and noise is therefore generated from the roller chain itself.
A chain transmission assembly combining a sprocket having a resilient member and a roller chain as shown in the following is well-known for reducing this kind of noise.
FIGS.
9
(
a
)-
9
(
b
) are an operational view illustrating the state of meshing of a related sprocket having a resilient member and a roller chain. This configuration is substantially the same as the configuration shown in FIGS.
8
(
a
)-
8
(
c
) and, the same numerals are applied therein after. A detailed description of the common elements is omitted.
In FIG.
9
(
a
), are annular resilient members
110
are fitted to a side of the sprocket
100
, rollers
111
are fitted in a freely rotatable manner to further link plates (not shown) for supporting the rollers
105
in a freely rotatable manner, and the rollers
111
are provided with centers of rotation
112
.
In FIGS.
9
(
a
)-
9
(
c
), the teeth bottoms
103
of the sprocket
100
are positioned just above the centers of rotation
101
.
The position of the rollers
105
is decided by the rollers
111
meshing with the resilient members
110
and the teeth bottoms
103
so that edges of the link plates
104
collide with the resilient members
110
and the rollers
105
therefore float from the teeth bottoms
103
of the sprockets
100
.
The wrapping radius of the roller chain in this case is taken to be (R+d
1
). The portions where the link plates
104
and the resilient members
110
overlap, i.e. the portions where the resilient members
110
are pushed so as to be compressed by the edge of the link plate
104
, are subjected to hatching.
In FIG.
9
(
b
), when the sprocket
100
rotates by an angle of &thgr;
1
in an counter-clockwise direction from the state in FIG.
9
(
a
), the rollers
105
and
106
move in an integral manner, the link plates
104
press and compress the resilient members
110
, and the centers of rotation
107
of the rollers
105
and the centers of rotation
108
of the rollers
106
fall by just a distance &bgr;
1
from the position of FIG.
9
(
a
).
In FIG.
9
(
c
), when the sprocket
100
rotates in an counter-clockwise direction so as to give rotation through an angle &thgr;
2
from the state in FIG.
9
(
a
), the teeth
102
become positioned just above the centers of rotation
101
and, the resilient bodies
110
are further compressed by a coercive force of the link plates
104
occurring due to the tension of the roller chain. The rollers
105
then mesh with the teeth bottoms
103
and the rollers
106
also mesh with the teeth bottoms
103
due to the compression of the resilient body
110
.
The wrapping radius of the roller chain in this case is R cos &thgr;
2
, and an amount of vibration of the roller chain in a vertical direction &bgr;
2
is &bgr;
2
=R+d
1
-R cos &thgr;
2
.
At this time, the link plates
104
collide with the resilient members
110
before the rollers
105
and
106
collide with the teeth bottoms
103
and the noise occurring when the rollers
105
and
106
collide with the teeth bottoms
103
is therefore absorbed.
FIG. 10
is a graph illustrating changes in wrapping radius of a related sprocket and also shows changes in the wrapping radius of the roller chain for the sprocket with no resilient body described in FIGS.
8
(
a
)-(
c
) and the sprocket with a resilient body described in FIGS.
9
(
a
)-(
c
), with the vertical axis showing a wrapping radius and the horizontal axis showing time.
The wrapping radius changes from R cos &thgr;
2
to R for the sprocket with no resilient body shown by the broken lines.
The wrapping radius changes from R cos &thgr;
2
to R(d+
1
) for the sprocket with a resilient body shown by the dashed lines.
From the above, with the sprocket
100
with the resilient body, an amount of vertical vibration d
1
of the roller chain becomes larger to the extent of d
1
=&bgr;
2
−&agr;2 compared to the sprocket
100
with the resilient body due to the resilient body
110
. This means that there is little reduction in noise due to the collisions of the teeth bottoms
103
and the rollers
106
or in noise due to vibration of the roller chain itself.
A chain transmission apparatus for reducing noise and improving quality based on a chain transmission assembly that combines a sprocket having a resilient member
110
and a roller chain as described in FIGS.
9
(
a
)-
9
(
c
) is disclosed in, for example, Japanese Laid-open Patent Publication No. Sho. 61-82164 entitled “Quiet Chain Approximation,” Japanese Patent Laid-open Publication No. Hei. 63-214566 entitled “sprocket,” and Japanese Patent Laid-open Publication No. Sho. 63-251654 entitled “Chain-Type Transmission Assembly.”
In
FIG. 1
of aforementioned publication No. Sho. 61-82164, a shock-absorbing ring
15
composed of a resilient body is fitted to a boss
14
of a sprocket b, link plates
11
of a roller chain a and formed in a substantially oval shape. A roller chain a meshes with a sprocket

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