Endless belt power transmission systems or components – Pulley with belt-receiving groove formed by drive faces on... – Speed responsive
Reexamination Certificate
2000-02-15
2002-01-01
Estremsky, Sherry (Department: 3681)
Endless belt power transmission systems or components
Pulley with belt-receiving groove formed by drive faces on...
Speed responsive
C474S012000
Reexamination Certificate
active
06334826
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a V belt type automatic transmission including a driving sheave mounted on a driving shaft, a driven sheave mounted on a driven shaft, a V belt extended between the driving sheave and the driven sheave, a thrust generating mechanism mounted on the driving shaft to produce a thrust for axially shifting an axially movable sheave part of the driving sheave to change the effective diameter of the driving sheave for automatic speed change.
2. Description of the Related Art
V belt type automatic transmissions are continuously-variable-speed transmissions used on four-wheel motor cars, such as all-terrain vehicles, motor scooters, and industrial vehicles including carriers. V belt type automatic transmissions are commonly called belt converters.
FIG. 7
shows a general power transmitting mechanism for vehicles, employing a V belt type automatic transmission. The V belt type automatic transmission includes a driving shaft
1
coupled with the crankshaft
7
of a prime mover (engine)
6
, and a driven shaft
2
coupled with he input shaft of a gear transmission G. A driving sheave
3
and a driving sheave thrusting mechanism
19
are mounted on the driving shaft
1
. A driven sheave
4
is mounted on the driven shaft
2
. Driving sheave
3
has a fixed sheave part
10
mounted on the driving shaft
1
and is restrained from axial and rotational movement and a movable sheave part
11
mounted on the driving shaft for axial movement. The driving sheave thrusting mechanism
19
includes flyweights
16
supported for turning on the back surface of the movable sheave part
11
, a pressure applying spring
20
biasing the movable sheave part
11
axially away from the fixed sheave part
10
, and a spider
15
in engagement with a guiding projections
32
formed on the back surface of the movable sheave part
11
to transmit the torque of the driving shaft
1
to the movable sheave part
11
and to guide the movable sheave part
11
for axial movement.
The movable sheave part
11
is formed integrally with the guiding projections
32
and a cover
21
. The cover
21
is stopped through a bearing
65
by a maximum driving sheave width adjusting mechanism
38
disposed on the right side, as viewed in
FIG. 7
, of the cover
21
.
In this V belt type automatic transmission, the rotating speed of the driving sheave
3
varies delicately according to the variation of the torque of the prime mover
6
and, consequently, the guiding projections
32
of the movable sheave part
11
vibrate circumferentially relative to the spider
15
and strike against the spider
15
to generate hammering noise. Generally, such hammering noise can be reduced by accurately finishing the circumferentially opposite surfaces of the guiding projections
32
and the spider
15
so that gaps between the same circumferentially opposite surfaces are small. More positive measures use guide shoes
40
as shown in FIG.
8
.
FIG. 8
is a view taken along the direction of the arrow VIII in FIG.
7
and showing the engagement of the spider
15
and the guiding projections
32
of the movable sheave part
11
(FIG.
7
). Guide shoes
40
each provided with a rubber layer
47
are interposed between the circumferentially opposite side surfaces
36
and
37
of the spider and the guide surfaces
32
a
and
32
b
of the guiding projections
32
on the opposite sides of the spider
15
, respectively. The guide shoes
40
are able to slide axially along the guide surfaces
32
a
and
32
b
, and the rubber layers
47
eases impact resulting from the variation of the torque to reduce the hammering noise.
The reduction of the circumferential gaps between the spider and the guiding projections is limited because the guiding projections and the spider must slide axially relative to each other and it is difficult to reduce the hammering noise effectively by reducing backlashes to about zero.
Even if the shocks are eased by using the guide shoes
40
provided with the rubber layers
47
, generation of hammering noise, though very light, is unavoidable because displacement of parts is unavoidable because the rubber layers
47
are inevitably subject to elastic deformation. Since the rubber layers
47
of the guide shoes
40
are permanently set in fatigue and the sliding surfaces of the guide shoes
40
are abraded during a long period of use and, consequently, hammering noise increases gradually with operating time.
The displacement of parts due to the elastic deformation of the rubber layers
47
promotes abrasion of the following parts in addition to the generation of hammering noise.
Parts that are abraded will be described with reference to
FIG. 1
showing a V belt type automatic transmission according to the present invention. Parts that will be abraded are (1) a bushing
13
fitted in the bore of a movable sheave part
11
, (2) a bushing
35
supporting a cover
21
formed integrally with the movable sheave part
11
, (3) bushings
26
supporting flyweights
16
, (4) bushings
29
supporting rollers
17
against which the flyweights
16
are pressed and (5) the contact surfaces of the flyweights
16
and the rollers
17
. Related techniques are disclosed in JP-A No. Hei 9-317836.
SUMMARY OF THE INVENTION
It is an object of the present invention to eliminate the circumferential gaps to stop the hammering noise, maintaining the smooth axial movement of the movable sheave part relative to the spider by properly designing the shape of the guide shoes placed in the circumferential gaps between the movable sheave part of the driving sheave and the spider and to suppress the abrasion of the aforesaid parts.
To solve the problems, the present invention provides a V belt type automatic transmission comprising: a driving sheave mounted on a driving shaft and including a fixed sheave part mounted on the driving shaft and restrained from axial movement and turning relative to the driving shaft, and a movable sheave part mounted on the driving shaft for axial movement; a driven sheave mounted on a driven shaft; a V belt extended between the driving sheave and the driven sheave; and a thrust generating mechanism mounted on the driving shaft to produce a thrust for axially shifting the movable sheave part of the driving sheave, including flyweights supported for turning on the movable sheave part, and a spider having parts in contact with the flyweights, mounted on the driving shaft and restrained from axial movement and turning relative to the driving shaft; wherein guide shoes are disposed in circumferential gaps between the spider and the movable sheave part to guide the movable sheave part for axial movement relative to the spider, and the guide shoes have the shape of a wedge.
According to the present invention, the spider is provided with recesses for receiving the wedge-shaped guide shoes to hold the wedge-shaped guide shoes on the spider.
According to the present invention, the wedge-shaped guide shoes are biased radially outward with auxiliary biasing means, such as springs.
REFERENCES:
patent: 4515575 (1985-05-01), Kinbara et al.
patent: 3-14957 (1991-01-01), None
patent: 9-317836 (1997-12-01), None
patent: 622755 (1978-08-01), None
patent: 624859 (1978-08-01), None
Estremsky Sherry
Kawasaki Jukogyo Kabushiki Kaisha
Lewis Tisha D.
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