Endless belt power transmission systems or components – Guard or housing for belt or pulley
Reexamination Certificate
2001-05-17
2003-02-25
Hannon, Thomas R. (Department: 3682)
Endless belt power transmission systems or components
Guard or housing for belt or pulley
Reexamination Certificate
active
06524203
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a power transmission device of an engine and, more particularly to a power transmission device of an engine having a mechanism for changing a rotational direction of output of the engine by substantially 90 degrees.
2. Description of the Related Art
There are various types of engines according to uses. For example, an engine includes a drive shaft extending in a direction orthogonal to a crank shaft of the engine. Such an engine is adopted as an engine of a shaft drive type motor cycle, an engine of a straddle-type four wheel all terrain vehicle, or the like.
FIG. 5
is a cross-sectional view showing a portion of an engine of a straddle-type four wheel all terrain vehicle, including a drive shaft
121
and its vicinity. In this engine, a gear-type transmission unit is accommodated in a gear case portion
131
integrated with a crank case. A counter shaft
142
of the gear-type transmission unit is shown in
FIG. 5. A
spur gear
143
is attached to the counter shaft
142
for transmitting power from an input shaft (not shown) of the gear-type transmission unit to an output shaft
111
of the gear-type transmission unit. The output shaft
111
of the gear-type transmission unit is rotatably supported by the gear case portion
131
of the crank case via a bearing
114
. A spur gear
116
is fixed to the output shaft
111
for driving the output shaft
111
. The spur gear
116
is in mesh with the spur gear
143
of the counter shaft
142
. Thereby, a rotational driving force of the spur gear
143
is transmitted to the output shaft
111
.
A gear case
132
is removably attached to the gear case portion
131
of the crank case. The gear case portion
131
and the gear case
132
are separate portions. A driving bevel gear
112
is attached to a tip end portion of the output shaft
111
. The tip end portion of the output shaft
111
, together with the driving bevel gear
112
, protrudes from the gear case portion
131
of the crank case and is accommodated in the gear case
132
. A drive shaft
121
is rotatably supported by the gear case
132
. A driven bevel gear
122
provided on the drive shaft
121
is accommodated in the gear case
132
.
More specifically, the driven bevel gear
122
is fixed to the drive shaft
121
. The drive shaft
121
is rotatably supported by a support member
123
via a bearing
124
. The support member
123
is attached to the gear case
132
. A portion of the drive shaft
121
, including the driven bevel gear
122
, is accommodated in the gear case
132
. Since the driven bevel gear
122
is in mesh with the driving bevel gear
112
, a direction of a rotational driving force of the output shaft
111
is changed by 90 degrees and the resulting force is transmitted to the drive shaft
121
in the gear case
132
.
An adjustment shim
115
is attached on a rear face of the driving bevel gear
112
. The adjustment shim.
115
enables adjustment of an axial position of the driving bevel gear
112
with respect to the output shaft
111
. An adjustment shim
125
i, is interposed between the gear case
132
and the support member
123
. These shims
115
,
125
serve to adjust tooth contact between the driving bevel gear
112
and the driven bevel gear
122
. The shims
115
,
125
are changed among shims having various thicknesses to select the shims
115
,
125
having thicknesses for preferable tooth contact between the driving bevel gear
112
and the driven bevel gear
122
.
However, the power transmission device of the engine described above have the following problems.
(1) Since the gear case
132
as the part separable from the crank case is placed laterally of the crank case, a lateral width of the engine and weight of the engine are increased. In addition, since the gear case
132
, i.e., a member different from the crank case is necessary, the number of parts of the engine and a manufacturing cost thereof are increased.
(2) When the shim
115
is changed or checked after the gear case
132
into which the drive shaft
121
has been assembled is attached to the gear case portion
131
of the crank case, a burdensome operation, i.e., removal of the gear case
132
including the drive shaft
121
from the crank case, becomes necessary. In particular, in a case where an engine has been assembled into a vehicle, the removal of the gear case
132
from the crank case is very burdensome.
As an example of a structure of a compact engine, it is known that a drive shaft is provided in a gear case portion of a crank case and a driven bevel gear of the drive shaft is accommodated in the gear case portion of the crank case. In this case, the tooth contact adjustment between the bevel gears is not necessarily easy, including the need for disassembly of the crank case, and its structure is complex. Such a related art is disclosed in Japanese Laid Open Patent Publication No. Sho. 63-71424, Japanese Laid Open Patent Publication No. Sho. 61-63828.
SUMMARY OF THE INVENTION
The present invention has been developed for obviating the above-described problems and an object of the present invention is to provide a power transmission device of an engine, which is lightweight, has few parts, and realizes a reduced width of the engine and easy adjustment of tooth contact between bevel gears when applied to the engine.
To solve the above-described problems, there is provided a power transmission device of an engine comprising: an output shaft of a gear-type transmission unit which is provided in parallel with a crank shaft of the engine and provided with a driving bevel gear at one end thereof, a driving force from the crank shaft being transmitted to the output shaft; a drive shaft placed in a direction orthogonal to the output shaft and provided with a driven bevel gear which meshes with the driving bevel gear; a gear case formed integrally with a crank case for accommodating the gear-type transmission unit and supporting a shaft situated in a previous stage of the output shaft at both ends of the shaft; a lid member; a first support member; a first shim; a second support member; and a second shim; wherein an opening is formed in the gear case to allow the output shaft to be pulled out of the gear case in a direction from the one end of the output shaft toward the other end thereof, the lid member is removably attached to the gear case such that it closes the opening, the first support member is removably attached to the gear case for rotatably supporting the output shaft, the first shim is interposed between the first support member and the gear case, the second support member is removably attached to the gear case for rotatably supporting the drive shaft, and the second shim is interposed between the second support member and the gear case.
Since the gear case and the crank case are integrally formed as described above, the engine can be made compact and the number of parts of the engine can be reduced. In particular, a width of the engine can be reduced. Besides, the first support member supporting the output shaft, and hence the first shim, can be taken out of the gear case through the opening by detaching the lid member from the gear case. Consequently, change and check of the first shim becomes easy. To form the gear case integrally with the crank case, for example, the crank case including the gear case as a portion of crank case may be manufactured by molding aluminum alloy.
It is preferable that in the power transmission device of the engine, the engine comprises a belt-type transmission unit for transmitting the driving force of the crank shaft to the gear-type transmission unit, and the drive shaft is situated in the gear case between the belt-type transmission unit provided in a side portion of the crank case and the gear-type transmission unit provided in the gear case. With such a structure, a dimension of the engine in a width direction thereof can be reduced.
It is preferable that in the power transmission device of the engine, the first support member supports the outpu
Kawamoto Yuichi
Takano Kiyohito
Hannon Thomas R.
Johnson Vicky A.
Kawasaki Jukogyo Kabushiki Kaisha
Marshall Gerstein & Borun
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