Internal-combustion engines – Frame construction – Horizontal cylinder
Reexamination Certificate
2001-05-16
2002-07-23
Kamen, Noah P. (Department: 3747)
Internal-combustion engines
Frame construction
Horizontal cylinder
Reexamination Certificate
active
06422193
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a crank shaft support structure of an engine and, more particularly to a crank shaft support structure of an engine in which a belt converter is attached to an end portion of the crank shaft.
2. Description of the Related Art
In a vehicle that travels on rough terrain such as a straddle-type all terrain vehicle, a belt converter is attached to an engine for the purpose of facilitating speed change operation.
FIG. 4
shows an example of a crank shaft support structure of an engine of a straddle-type four wheel all terrain vehicle in which the belt converter is attached to an end portion of the crank shaft.
As shown in
FIG. 4
, in this engine, a crank shaft
102
penetrates through a wall portion of a crank chamber
101
a
of a crank case
101
and a wall portion of a chain chamber
101
b
of the crankcase
101
. A pair of bearings
103
,
104
are provided on the wall portion of the crank chamber
101
a
through which the crank shaft
102
penetrates, and a bearing
112
for the belt converter is provided on an outer wall portion
111
of the chain chamber
101
b
through which the crank shaft
102
penetrates. The crank shaft
102
is held by the pair of bearings
103
,
104
, and the bearing
112
for the belt converter such that the crank shaft
102
is rotatable with respect to the wall portion of the crank chamber
101
a
and the outer wall portion
111
of the chain chamber
101
b.
A large end portion
104
a
of a connecting rod
104
connected to a piston
105
is connected to a crank pin
106
of the crank shaft
102
by means of a bearing
107
. A belt converter
108
is attached to a portion
102
a
of the crank shaft
102
that is protruded from the wall portion of the chain chamber
101
b
. The belt converter
108
is attached such that a main shaft
109
is connected to the end portion
102
a
of the crank shaft
102
and a drive pulley
110
is attached to the main shaft
109
. The bearing
112
for the belt converter is constituted by a double row ball bearing so that it withstands belt tension of the belt converter
108
because the bearing
112
is subject to the belt tension.
An oil passage
115
is formed through an inside of the outer wall portion
111
of the chain chamber
101
b
, an inner peripheral face of the outer wall portion
111
through which the crank shaft
102
penetrates, and inside of the crank shaft
102
, to a portion
120
where the crank shaft
102
and the large end portion of the connecting rod are connected to each other. Through the oil passage
115
, lubricating oil is forcibly fed by an oil pump (not shown) to the portion
120
where the large end portion of the connecting rod and the crank shaft
102
are connected to each other. Reference numeral
114
denotes a sprocket for driving a cam shaft (not shown).
Publication of Japanese Examined Patent Application No. Hei. 2-29889 discloses a general crank shaft support structure of an engine in which a bearing for supporting a crank shaft is constituted by a plain bearing, and from the plain bearing, oil is forcibly fed to a portion where a large end portion of a connecting rod and a crank shaft are connected to each other.
By the way, when the conventional engine is mounted on the straddle-type four wheel all terrain vehicle, the crank shaft
102
is placed in a lateral direction of a vehicle body. The conventional engine is a single-cylinder engine, but a two-cylinder engine is sometimes mounted. In this case, a width of the engine is increased because the number of cylinders is increased as compared to the case where the single-cylinder engine is mounted. When a total width of the engine and the belt converter is too large in the straddle-type four wheel all terrain vehicle, a rider straddling a seat makes contact with side faces thereof. Therefore, it is necessary to limit the engine width.
However, in the crank shaft support structure of the conventional engine, a portion to be supported by the bearing
112
for the belt converter and a portion in which the oil passage
115
is formed are required in a portion of the crank shaft
102
that is outwardly protruded from a wall portion of the crank chamber
101
a
. For this reason, the length of the crank shaft
102
, and hence the width of the engine, are increased.
SUMMARY OF THE INVENTION
Under the circumstances, an object of the present invention is to provide a crank shaft support structure which is capable of reducing a length of a crank shaft of an engine to which a belt converter is attached.
To achieve the above-described object, according to the present invention, there is provided a crank shaft support structure of an engine comprising: a crank shaft provided such that it penetrates through a crank case, including a crank pin portion situated in the crank case, to which a large end portion of a connecting rod is connected, and having one end portion to which a belt converter is connected; a first bearing for holding a portion of the crank shaft that penetrates through the crank case, which is close to the one end portion of the crank shaft, rotatably with respect to the crank case, the first bearing being constituted by a double row ball bearing; a second bearing for holding a portion of the crank shaft that penetrates through the crank case, which is close to the other end portion of the crank shaft, rotatably with respect to the crank case; and means for forcibly feeding lubricating oil from the other end portion's side of the crank shaft, through an oil passage formed inside of the crank shaft, and to a portion where a large end portion of a connecting rod and the crank pin portion are connected to each other.
With this configuration, since the oil is fed to the portion where the large end portion of the connecting rod and the crank shaft are connected to each other, from an opposite side of the portion where the belt converter is provided, the belt converter can be provided adjacently to the first bearing. Also, a large load capacity is demanded of the bearing which is subjected to load from the belt converter, because it needs to withstand belt tension of the belt converter which is applied to the bearing in the radial direction thereof. Since the first bearing is constituted by the double row ball bearing with a load capacity large enough to withstand the belt tension, a bearing for the belt converter can be dispensed with. Consequently, the length of the crank shaft and hence, the width of the engine can be reduced.
In this case, the second bearing may be a plain bearing, the oil passage may be formed in the crank shaft such that the oil passage extends from a peripheral face of a portion of the crank shaft that is fittingly inserted into the second bearing, through the inside of the crank shaft, and to the portion where the large end portion of the connecting rod and the crank pin portion are connected to each other, and the means for forcibly feeding oil may be adapted to feed the lubricating oil to the second bearing, and forcibly feed the lubricating oil from the second bearing, through the oil passage, and to the portion where the large end portion of the connecting rod and the crank pin portion of the crank shaft are connected to each other. With this configuration, it is not necessary to provide an oil passage at a portion of the crank shaft that is situated outwardly of the second bearing. Consequently, the crank shaft can be further reduced.
These objects as well as other objects, features and advantages of the invention will become apparent to those skilled in the art from the following description with reference to the accompanying drawings.
REFERENCES:
patent: 4854274 (1989-08-01), Dingess
patent: 2-29889 (1983-02-01), None
patent: 6-346713 (1994-12-01), None
Kamen Noah P.
Kawasaki Jukogyo Kabushiki Kaisha
Marshall Gerstein & Borun
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