Note: Descriptions are shown in the official language in which they were submitted.
CA 02228102 1998-O1-29
ENGINE SUPPORTING DEVICE FOR A VEHICLE
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to an engine supporting device for a vehicle
such
as a snowmobile or the like.
Description of Background Art
Japanese Patent Publication No. Sho 61-27202 discloses a snowmobile in
which front and rear portions of an engine are mounted to a vehicular body
through
rubber members; a reduction gear case is supported on the vehicular body
separately
from the engine; and power is transmitted from the engine to the reduction
gear
through a V-belt type transmission. Japanese Patent Laid-open No. Sho 61-
295129
discloses a structure in which an engine including a power transmission system
similar
to that described above is connected to a reduction gear case through a
damper.
Japanese Patent Publication No. Hei 5-17048 disclosed a structure in which a
power
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transmission system similar to that described above is used and an engine is
connected
to a :reduction gear case through a link mechanism.
Incidentally, in cases similar to the above-described structures where an
engine
having an output shaft provided with a drive pulley and a reduction gear case
having an
input: shaft provided with a driven pulley are separately supported on a
vehicular body
and a belt is wound around the drive pulley and the driven pulley, vibration
is applied
from the driven pulley to the engine against a drive force applied from the
drive pulley
side to the driven pulley.
On the other hand, it is known that an engine may be supported on a vehicular
body through elastic members positioned at least at two points on front and
rear sides
of a ~~rank case. However, if the elastically supporting structure is used for
the above-
described power transmission system, the elastic members at the front and rear
moulting portions are deformable at random, and accordingly, the engine may
be, at
each mounting portion, turned around a mounting shaft of the elastic member
and/or
moved in the direction perpendicular to the mounting shaft, for example, in
the
longitudinal direction.
To be more specific, each mounting portion functions as a supporting point
around which the engine is turned due to vibration of the engine, and also
functions to
move: the engine in the direction perpendicular to the mounting shaft. As a
result,
vibration of the entire engine becomes larger, and thereby a distance between
the drive
pulley and the driven pulley tends to vary.
Accordingly, in the structure disclosed in Japanese Patent Publication No. Sho
61-27202 or Japanese Patent Laid-open No. Sho 61-295129, vibration of the
engine
cannot be suppressed, which may exert an adverse effect on accessories.
Further, the
configuration disclosed in the Japanese Patent Publication No. Hei 5-17048 can
solve
such a problem. However, it requires a high level technique in terms of the
setting of a
link mounting angle or the like.
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SUMMARY AND OBJECTS OF THE INVENTION
To solve the above problem, according to the present invention, there is
provided an engine supporting device for a vehicle in which an engine and a
gear box
containing a reduction gear train are separately formed and separately
supported on a
vehicular body. A drive pulley of a V-belt type transmission is provided on an
output
shaft of the engine and a driven pulley of the V-belt type transmission is
provided on
an input shaft of the gear box. A V-belt is wound around the drive pulley and
the
driven pulley. The engine supporting device includes two mounting portions
supported
by the vehicular body, which are provided on a crank case of the engine on
front and
rear sides of the drive pulley in such a manner that the drive pulley is put
between the
mouclting portions wherein one of the front and rear mounting portions mainly
functions as a supporting point around which the engine is turned due to a
drive
reaction force of the V-belt type transmission. The other of the front and
rear
mounting portions is mounted on the vehicular body by a mounting shaft through
an
elastic member and mainly functions as a member for absorbing the vibration of
the
engine by deformation of the elastic member.
In the above engine supporting device, preferably, the front and rear mounting
portions are mounted on the vehicular body through front and rear elastic
members
respectively. One of the front and rear elastic members is higher in hardness
than the
other of the front and rear elastic members, or either of the front and rear
elastic
members is formed of a ring bush.
Further, in the above engine supporting device, preferably, the mounting
portion mainly functions as a supporting point around which the engine is
turned is
connected to the vehicular body through a tension rod, or is connected to the
vehicular
body through a mounting shaft and a collar or bearing turnably supporting the
mounting shaft.
Since either of the front and rear mounting portions mainly functions as a
supporting point around which the engine is turned, when the engine is applied
with a
drive: reaction force of the V-belt type transmission, the movement of the
engine in the
longitudinal direction of the body is restricted because the supporting point
around
which the engine is turned substantially lies on the extension of a belt line.
In the other
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mounting portion, the elastic member is elastically deformed to move the
engine in the
direction perpendicular to the mounting shaft, to thus absorb vibration of the
engine.
In this way, the main functions for suppressing vibration of the engine can be
differently distributed to the front and rear mounting portions by a
relatively simple
structure, as a result of which the movement of the entire engine due to
vibration of
the engine can be suppressed and thereby a change in distance between the
drive pulley
and t:he drive pulley can be reduced.
Since vibration of the engine can be thus suppressed, vibration transmitted to
accessories can also be reduced, to thereby enhance the durability and improve
the
ridin;~ comfort. Such an engine supporting structure can be provided without
necessity
of an,y special high level technique.
In the case where the front and rear mounting portions are connected to the
vehicular body through the front and rear elastic members, if the hardness of
the front
and rear elastic members are different from each other, the mounting portion
using the
harder elastic member mainly functions as a supporting point around which the
engine
is turned, and the other mounting portion mainly functions to absorb vibration
of the
engine with the elastic member of the mounting portion being relatively
largely moved
in the: direction perpendicular to the mounting shaft. Further, the functions
can be
distributed to the front and rear mounting portions with an extremely simply
structure
in which the hardness of the elastic members are made different from each
other.
In the case where the front and rear mounting portions are connected to the
vehicular body through the front and rear elastic members, if one of the
elastic
members is formed of the ring bush, the ring bushing is liable to mainly
function as a
supporting point around which the engine is turned because the ring bushing
is, in
general, elastically harder. Accordingly, the functions can be simply
distributed to the
front and rear mounting portions only by changing the form of the elastic
members.
In the case where one mounting portion is connected to the vehicular body
through the tension rod, the tension rod allows the engine to be turned and to
be
restricted in its the longitudinal movement due to vibration of the engine,
and the other
mounting portion can absorb vibration of the engine by elastic deformation of
the
elastic member.
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Further, in the case where one mounting portion is connected to the vehicular
body not through the elastic member but through the mounting shaft and the
collar or
bearing for turnably supporting the mounting shaft, the mounting shaft of the
mounting
portion acts as the center of the turning of the engine and thereby the
position of the
turning center of the engine can be kept constant, and the other mounting
portion can
absorb vibration of the engine by elastic deformation of the elastic member.
Further scope of applicability of the present invention will become apparent
frorr,~ the detailed description given hereinafter. However, it should be
understood that
the detailed description and specific examples, while indicating preferred
embodiments
of th.e invention, are given by way of illustration only, since various
changes and
modifications within the spirit and scope of the invention will become
apparent to
those skilled in the art from this detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will become more fully understood from the
detailed description given hereinbelow and the accompanying drawings which are
given by way of illustration only, and thus are not limitative of the present
invention,
and 'wherein:
Fig. 1 is a side view of a snowmobile;
Fig. 2 is a side view of the snowmobile in a state in which a body cover is
removed;
Fig. 3 is a schematic plan view in development of a drive/power transmission
systf;m;
Fig. 4 is a left side view of the drive/power transmission system;
Fig. 5 is a right side view of the drive/power transmission system;
Fig. 6 is a sectional plan view of an engine portion;
Fig. 7 is a sectional view of a driven pulley and a final reduction gear
portion;
Fig. 8 is a sectional view showing a supporting structure of a drive shaft;
Fig. 9 is a left side view, similar to Fig. 4, of essential portions of
another
embodiment;
Fig. 10 is a right side view, similar to Fig. 4, of the embodiment shown in
Fig.
9;
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Fig. 11 is a sectional view of a front side body mounting portion in the
embodiment shown in Fig. 9;
Fig. 12 is a view, seen from the right side of a crank case, of the front side
body
mounting portion;
Fig. 13 is a schematic plan view showing an arrangement relationship of a
tension rod in the front side body mounting portion shown in Fig. 12; and
Fig. 14 is a view, similar to Fig. 13, showing a further
embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
A schematic structure of the entire snowmobile will be first described with
reference to Figs. 1 and 2. The snowmobile includes a front body thereof
having a
steering ski 1 supported by a telescopic type erecting front suspension 2, and
at a rear
body thereof a track device 3 driven by an engine (described later).
A floor 4 is provided over the track device 3. A driver stands on the floor 4
and
operates a handlebar 5. The floor 4 is formed into an approximately reversed U-
shape
in tr:~nsverse cross section. Right and left side surfaces of the floor 4 are
taken as
erec~:ed walls.
A body cover 6 for hovering a body includes a front cover 7, side covers 8,
and
a rear cover 9. The front cover 7 covers a portion extending rearward over an
engine
room at the front body. The side covers 8 cover portions of the body on both
sides of
the front cover 7. The rear cover 9 extends longer rearwardly from the side
covers 8
along right and left sides of the floor 4 and covers side portions of a
driver's space over
the floor 4.
As will be apparent from Fig. 2, a head pipe 10 is provided at the front body
and the front suspension 2 is fixedly surrounded by the head pipe 10. An inner
tube 11
of th.e front suspension 2 extends obliquely in the vertical direction with a
lower end
portion thereof turnably supported by an outer tube 12.
A handle boss 13 is mounted around an outer periphery of an upper end
portion of the inner tube 11 in such a manner as to be turnable with the inner
tube 11
3o taken as a pivot and to be axially fixed. The handle boss 13 is connected
to the upper
end portion of the outer tube 12 with a suspension link 14.
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The suspension link 14 is extensible by vertical movement of the outer tube
12.
An intermediate portion of the suspension link 14 projects in a state being
bent
forwardly so as to sufficiently ensure a chamber space (described later)
surrounded by
a portion of the body cover 6 positioned in front of the head pipe 10.
A lower end portion of a handle post 15 is connected to a top portion of the
handle boss 13 in such a manner as to be vertically rockable through a handle
post
pivot; 16. A handle link 18 composed of a damper is mounted between a link
stay 17
and a portion of the handle post 15 near the handlebar 5. The link stay 17
integrally
extends obliquely upwardly and rearwardly from the top portion of the handle
boss 13.
1 o These front suspension 2, head pipe 10, and handle boss 13 form a steering
shaft of the steering ski 1. The handle post pivot 16 is positioned between a
rear end
portion of the steering ski 1 and a front end portion of the track device 3.
A pair of right and left main frames 20 extend obliquely downwardly and
reanvardly from the head pipe 10. Each main frame 20 has a down-tube 21 and a
pivot
15 plate 22. The down-tube 21 extends obliquely forwardly and downwardly from
a
portion of the main frame 20 near the head pipe 10, and the pivot plate 22
extends
dow~iwardly from a rear portion of the main frame 20.
A water-cooled type two-cycle/single-cylinder engine 25 is supported on the
down-tubes 21 and the pivot plates 22 through a front side elastic mount 23
and a rear
20 side elastic mount 24. A cylinder portion 26 of the engine 25 is positioned
between the
right and left main frames 20, and the center of the engine 25 is positioned
at
approximately a central portion of the body.
A water pump 28 and an oil pump 29 are provided on a lower portion of a
crank case 27 constituting the engine 25. The water pump 28 is used to supply
cooling
25 water from a heat exchanger 30 contained in a ceiling portion of the floor
4 into the
cylinder portion 26.
The hot water from the cylinder portion 26 is fed to the heat exchanger 30 to
be effectively cooled, and is then returned into the water pump 28. A water
inlet 31 of
the heat exchanger 30 is provided sidewardly of the head pipe 10.
30 The heat exchanger 30, which has a width nearly equal to a width of the
ceiling
portion of the floor 4, has a wide surface area. Also, the heat exchanger 30
is
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superimposed on the ceiling portion of the floor 4 in the vertical direction
to mutually
incrf;ase the rigidity of the heat exchanger 30 and the floor 4.
The oil pump 29 is connected to an oil tank 33 supported on an upper front
portion of the floor 4 together with a battery 32. The work for maintenance of
the
battery 32 and the oil tank 33 can be performed by opening a lid 34 formed to
a
partitioning wall 7a which longitudinally partitions the driver's space over
the floor 4
from the engine room in front of the driver space.
The partitioning wall 7a is formed of a portion of the front cover 7 which
extends around to a back surface of a fuel tank 35 while covering an upper
surface of
1o the fuel tank 35. The fuel tank 35 is positioned in front of the battery 32
and the oil
tank 33 and is supported on the main frames 20. A tank cap 36 is provided on
the fuel
tank 35.
An exhaust chamber 37 extends forward from an exhaust port of the engine 25,
and i.s arranged in the chamber space surrounded by the body cover 6
positioned in
front: of the engine 25. In the chamber space, the exhaust chamber 37 extends
in the
form. of an approximately semi-circular shape in a plan view along the inner
surface of
the ir~ody cover 6. A silencer 38 connected to the exhaust chamber 37 is
disposed along
the upper side of the exhaust chamber 37. The piping of the exhaust system
thus
meanders in approximately a two-stage manner. The exhaust gas is finally
exhausted
downwardly toward the front side of the engine 25 from a tail pipe 39.
A drive output of the engine 25 is transmitted through a V-belt type
transmission 40 to a gear box 41 containing a final reduction gear mechanism.
The
gear box 41 is supported on the main frames 20 and the pivot plates 22 and is
adapted
to finally reduce the drive force transmitted from the V-belt type
transmission 40 and
to rotate a drive shaft 42.
Drive wheels 42a are integrally supported by the drive shaft 42, and are
rotated
integrally with the drive shaft 42. Outer peripheral portions of the drive
wheels 42a are
meshed with irregularities formed on the inner surface of a track belt 43 for
driving the
track: belt 43.
With respect to the drive shaft 42, the left end portion is supported by the
pivot
plate 22 and the right end portion is supported by the gear box 41. Front end
portions
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of a pair of right and left rear arms 44 extending obliquely downwardly and
rearwardly
are l:urnably supported around both the end portions of the drive shaft 42.
Both rear end portions of the rear arms 44 are connected to front errd
portions
of right and left side rails 47 extending in parallel to each other through an
idle shaft 46
of an idle wheel 45.
Shaft position adjusting plates SO for supporting the idle shaft 49 of the
idle
wheel 48 are supported by both rear end portions of the side rails 47 in such
a manner
as to be movable fore and aft. A lower end portion of a rear link 51 disposed
in parallel
to the rear arm 44 is connected to each shaft position adjusting plate 50
through a
connecting member 51 a.
An upper end portion of the rear link 51 is rotatably mounted to a stay 52
projecting downwardly from a side surface of the floor 4 through an idle shaft
53. A
track belt 43 is wound around the idle wheels 54 supported by the idle shaft
53,
additional idle wheels 46 and 48, and the drive wheels 42a supported by the
drive shaft
42, t:o constitute the track device 3.
The track device 3 forms a parallelogram link formed of the floor 4, rear arms
44, ;>ide rails 47, and rear links 51. A cross-plate 55 is formed between
intermediate
portions of the right and left side rails 47, and both a damper 56 and a
suspension
spring 57, which constitute a rear suspension, extending obliquely and
vertically from
the <;ross-plate 55 in such a manner as to be widen toward the upper side in a
side
vie~~.
An upper end portion of the damper 56 is supported by a cross-pipe 58
supported between right and left extensions 22a extending rearwardly in the
floor 4
frorr~ rear portions of the pivot plates 22. An upper end portion of the
suspension
spring 57 is supported by a spring holder 59 turnably supported by the idle
shaft 53.
The spring holder 59 is supported by a rear end portion of a spring holder rod
59a. The
spring holder rod 59a extends rearwardly with its front end co-fastened with
an upper
end portion of the damper 56.
Next, a detailed structure of the drive/power transmission system will be
described with reference to Figs. 3 to 8. The drive/power transmission system
is
constituted of the engine 25, V-belt type transmission 40 and gear box 41,
which are
disposed in an approximately N-shape (see Fig. 5). As will be apparent from
Fig. 4, the
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engine 25 is a two cycle engine in which air is sucked from a carburetor 19
into a crank
cast; 27 and is preliminarily compressed in the crank case 27.
Fig. 3 shows a schematic configuration of the drive/power transmission system.
Refernng to Fig. 3, one end of a crank shaft 60 of the engine 25 is mounted
with an
ACG 61 and the other end thereof extends outwardly from the crank case 27. A
drive
pulley 62 constituting the known V-belt type transmission 40 is mounted on the
extension of the crank shaft 60.
In the V-belt type transmission 40, a V-belt 63 is wound around the drive
pulley 62 and a driven pulley 64 disposed rearwardly and upwardly of the drive
pulley
62 (;see Figs. 3 and 5), to perform a primary continuous variable transmission
of a
rotational output of the crank shaft 60 on the gear box 41 side.
With respect to arrangement of the parts constituting the drive/power
transmission system, the gear box 41 is disposed to the right in the width
direction of
the body from the drive pulley 62 of the V-belt type transmission 40 and also
to the
right from the main frames 20. The engine 25 and the V-belt type transmission
40 are
disposed inside the right and left main frames 20. More specifically, the V-
belt type
transmission 40 is held between the gear box 41 and the engine 25.
The gear box 41 includes a case composed of right and left halves 41 b and 41
a.
A biiaxial in-line type gear train composed of an input gear 65, an idle gear
66 and a
final gear 67 is contained in the case. An input shaft 68 mounted with the
input gear 65
extends outwardly from the gear box 41 and the drive pulley 64 is mounted on
the
extension of the input shaft 68.
An idle shaft 69 mounted with the idle gear 66 extends outwardly from the gear
box 41 opposite to the input shaft 68, and a brake disk 70 is mounted to the
extension
of the idle shaft 69. The brake disk 70 is braked by a brake caliper 70a
provided on the
half case 41b of the gear box 41 (see Fig. 5).
A final shaft 71 mounted with the final gear 67 is a hollow shaft, into which
one
end of the drive shaft 42 is removably fitted. The gear box 41 is filled with
lubricating
oil in which the gear train is dipped.
As will be apparent from Fig. 6, a starter driven gear 73 is supported, at a
pori:ion near the ACG 61, by the crank shaft 60 of the engine 25 through a one-
way
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clutch 72. The movement of the starter driven gear 73 in the thrust direction
is
restricted by a gear presser plate 74.
A balancer drive gear 76 fastened by a nut 75 is provided on the crank shaft
60,
which is meshed with a balancer driven gear 77 for rotating a balancer shaft
78 is
disposed in parallel to the crank shaft 60.
A pump drive gear 80 is mounted on one end of the balancer shaft 78 with a
bolt 79, and a balancer weight 81 is integrally provided on the other end of
the
bala.ncer shaft 78. Two intermediate portions of the balancer shaft 78 near
the balancer
driven gear 77 and the balancer weight 81 are rotatably supported on the crank
case 27
by bearings 82 and 83. A seal 84 is provided outside the bearing 83 on the
balancer
wei,ht 81 side.
A balancer chamber 85 for containing the balancer shaft 78 is partitioned, by
a
journal wall 87, from a crank chamber 86 for containing a crank weight 60a.
The
bala.ncer driven gear 77 and the balancer weight 81 are disposed outside the
crank
chamber 86. The balancer chamber 85 is filled with lubricating oil in the
crank case 27
and thereby the bearings 82 and 83 are dipped in the oil. The balancer chamber
85 is
sealed from the exterior with a seal 84.
The crank shaft 60 is rotatably supported, at a portion near the crank weight
60a, on a journal wall 87 by a bearing 88, and the outside of the crank
chamber 86 is
2o sealed with seals 89a and 89b.
As will be apparent from Fig. 7, the input shaft 68 of the gear box 41 is
rota.tably supported by bearings 90 and 91, and the extension of the input
shaft 68
extending from the gear box 41 on the driven pulley 64 side is provided with a
seal 92.
The idle shaft 69 is, similarly, rotatably supported by bearings 93 and 94,
and
the extension of the idle shaft 69 extending from the gear box 41 on the brake
disk 70
side: is provided with a seal 95. A spline groove 97 is formed in an outer
peripheral
pon:ion of the extension portion 96. A boss 98 to be fitted around the outer
periphery
of tlhe extension portion 96 is provided at a central portion of the brake
disk 70. A
spline groove 99 is formed in an inner peripheral surface of the boss 98, and
is engaged
with the spline groove 97, whereby the boss 98 is movable in the axial
direction.
The final shaft 71 is, similarly, rotatably supported by bearings 100 and 101.
The final shaft 71 is a hollow shaft with one end 102 being opened on a side
surface of
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the gear box 41. A seal 103 is provided around the one end 102. A spline
groove 104
is firmed in an inner surface of the one end 102 in such a manner so as to
extend
inwardly from the open end side.
One end 105 of the drive shaft 42 is fitted on the one end 102 side. A spline
groove 106 formed in an outer peripheral portion of the one end 105 is engaged
with
the spline groove 104, allowing the final shaft 71 to be rotated integrally
with the drive
shaft 42. A cap 108 is fitted in the other end 107 of the final shaft 71 to
seal the hollow
final shaft 71.
As will be apparent from Fig. 8, both end portions of the drive shaft 42 pass
through and are supported by bearing supporting portions 110 provided at front
end
portions of the right and left rear arms 44. The other end opposite to the one
end 105
forms a small diameter portion 111 which is rotatably supported by a bearing
112
supported by the pivot plate 22. A leading end of the small diameter portion
111 forms
a projecting threaded portion 113 which is fastened to the bearing 112 by a
nut 114.
An outer periphery of the intermediate portion of the drive shaft 42 is formed
into a hexagonal portion 115 to be engaged with hexagonal holes formed in
centers of
the boss portions 116 of the drive wheels 42a, whereby the drive wheels 42a
are
rotatable integrally with the drive shaft 42.
Next, the engine supporting structure will be more fully described with
reference to Figs. 4 and 5. As will be apparent from these figures, a ring
bushing 130,
which is one example of the front side elastic mount 23, is fitted in a front
side body
mounting portion 120 integrally projecting forward from the front portion of
the crank
cash 27. The ring bushing 130 is a cylindrical member having,a known structure
in
which a rubber 133 is packed between metal made inner and outer cylinders 131
and
132..
A rear side body mounting portion 140 integrally projects rearwardly from the
rear portion of the crank case 27. A mount rubber 150, which is one example of
the
rear side elastic mount 24, is fitted in the rear side body mounting portion
140. The
mount rubber 150 includes a metal collar 152 at an axial portion thereof and a
3o cylindrical rubber 151 integrally provided around the metal collar 152. In
addition,
corrugated grooves are formed in an outer peripheral surface portion of the
cylindrical
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rubber 151. The mount rubber 150 is fitted in a mounting hole 141 formed
through the
rear side body mounting portion 140.
The front side elastic mount 23, represented by the ring bush, is higher in
hardness than the rear side elastic mount 24, represented by the mount rubber.
Each
mount is connected to the body side with a mounting bolt (not shown) through
an
inner cylinder 131 or a collar 152. It should be noted that a ring bushing and
a mount
rubber which will be described in another embodiment with reference to Figs.
11 and
12 ;are substantially similar to the above ring bushing and mount rubber shown
in Figs.
4 and 5 in terms of structure, mounting structure to the body mounting portion
and the
bodly side.
The function of this embodiment will be described below. When vibration is
applied from the driven pulley 64 side to the engine 25, the front side body
mounting
portion 120, which has the front side elastic mount 23 (ring bushing 130)
being higher
in hardness than the rear side elastic mount 24, allows the engine 25 to be
turned
around the front side body mounting portion 120 along the rotational direction
thereof,
and it also allows the engine 25 to be restricted in its movement in the
longitudinal
direction of the body.
At the same time, the rear side elastic mount 24 (mount rubber 150), which is
softer than the front side elastic mount 23, is elastically deformed and
thereby it allows
the engine 25 to be moved in the radial direction of the rear side elastic
mount 24.
Thus, the rear side elastic mount 24 absorbs vibration of the engine. As a
result, it is
possible to reduce the movement of the engine 25 due to vibration of the
engine as a
whole, and hence to easily keep the center-to-center distance between the
drive pulley
62 ~md the driven pulley 64 at a nearly constant value.
Further, since the mounting position at which the front side body mounting
portion 120 is mounted to the down tube 21 by the front side elastic mount 23
is
located near the extension of an action line connecting the centers of the
drive pulley
62 and the driven pulley 64 to each other (see Fig. 5), the movement of the
engine 25
due to the drive reaction force can be further reduced.
Further, vibration of the engine 25 can be suppressed by a simply design in
which the hardness of the front side elastic mount 23 is different from that
of the rear
side. elastic mount 24. As a result, vibration transmitted to accessories can
be reduced,
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to thereby enhance the durability and improve the driving comfort. Also, the
effect can
be obtained only by mounting the front side elastic mount 23 and the rear side
elastic
mount 24 without any specific technique.
Further, by combination of the ring bushing 130 and the mount rubber 150
which are structurally different from each other in hardness as the elastic
body, the
hardness of the front and rear mounts can be easily made different from each
other.
In this way, the main functions for suppressing vibration of the engine can be
differently distributed to the front and rear mounting portions with a
relatively simple
stru~~ture, as a result of which vibration of the entire engine can be
suppressed and
thereby a change in distance between the drive pulley and the driven pulley
can be
reduced.
Since vibration of the engine can be thus suppressed, vibration transmitted to
accessories can be also reduced, to thereby enhance the durability and improve
the
riding comfort. Further, the functions can be simply distributed to the front
and rear
elastic members without necessity of any special high-level technique.
The change in hardness between the front and rear elastic members is not
limited to the combination of the different structures of the front and rear
elastic
merr~bers, for example, the combination of the ring bushing 130 and the mount
rubber
150 in this embodiment. The front and the rear elastic members may be of the
same
structure, for example, the ring bushing 130 or mount rubber 150, and the
elastic
constants (that is, hardness) of the elastic materials such as rubber forming
both the
elastic members of the front and rear mounting portions may be made different
from
each other.
Next, another embodiment of the engine supporting structure will be described
with reference to Figs. 9 to 13. It should be noted that parts common to those
shown
in the previous embodiment are indicated by the common characters. Figs 9 and
10 are
similar to Figs. 4 and 5; Fig. 11 is a sectional view taken on line 11-11 of
Fig. 12,
showing a rear side body mounting portion 120; Fig. 12 is a view illustrated
from a
right: side of the crank case 27, showing the front side body mounting portion
120,
with parts partially omitted; and Fig. 13 is a schematic plan view showing an
arrangement relationship of a tension rod.
CA 02228102 1998-O1-29
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Referring to Figs. 9 to 13, a main mount 122 is fitted in a mounting hole 121
in
the front side body mounting portion 120 in such a manner as to pass
therethrough in
the width direction of the body. The main mount 122 is represented by a mount
rubber
150 having corrugated grooves at its outer peripheral surface portion like the
mount
rubber in the previous embodiment. In this embodiment, since the crank case 27
is
divided into right and left parts, a pair of right and left parts of the mount
rubber 150
are press-fitted in the mounting hole 121 from both end sides, and end
portions of both
collars 152 of the right and left parts of the mount rubber 150 are connected
to each
other by means of a joint collar 123.
Right and left sides of the front side body mounting portion 120 abut onto a
boss 125 and a supporting plate 126 through elastic seats 124 respectively.
The boss
12_'~ is provided at a lower end portion of the down-tube 21 (see Fig. 2)
extending
downwardly from the left side main frame 20. The supporting plate 126 is
mounted to
a lower end portion of the down-tube 21 a extending downwardly from the right
side
main frame substantially in parallel to the down-tube 21, as shown in Fig. 12.
The boss
12'_> and the supporting plate 126 are fastened to both of the sides of the
front side
body mounting portion 120 by a bolt 127 passing therethrough and a nut 128.
The front side body mounting portion 120 has another mounting hole 129
formed under the mounting hole 121. A first mount 170 for a tension rod, which
is one
example of the ring bushing 130, is fitted in the mounting hole 129. The ring
bushing
130 forming the first mount 170 has the same structure as that described
above, that is,
a known damper in which a rubber 133 is packed between inner and outer
cylinders
131, and 132. The ring bushing 130 is higher in hardness than the mount rubber
150.
One-sided ends of a pair of connecting plates 160 abut onto both sides of the
first mount 170 for the tension rod and are fastened to each other by means of
a bolt
l6ll and a nut 162. The right and left connecting plates 160 extend forwardly
in parallel
to each other, and front end portions thereof abut onto both ends of a second
mount
17'.l for a tension rod and are fastened to each other by means of a bolt 163
and a nut
161. The second mount 171 has another ring bushing having the same structure
as that
of l;he ring bushing 130.
The second mount 171 for the tension rod has the same structure as that of the
ringing bushing 130, and is fitted and welded to the extended end portion of
the
CA 02228102 1998-O1-29
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supporting plate 126. The right and left connecting plates 160 function as a
tension rod
cormecting the ring bushing 130 on the engine side to the ring bushing 171 on
the body
side. .
As shown in Fig. 13, the tension rod ( 160, 170, 171 ) is located on the
extension of the V-belt 63 of the V-belt type transmission 40. The center line
C of the
tension rod is positioned within a plane parallel to a rotational plane of the
V-belt 63,
and the front side body mounting portion 120 and first and second mounts 170
and
171. for the tension rod are located near the extension of the action line
connecting the
centers of the drive pulley 62 and the driven pulley 64 (see Fig. 10).
The second mount 171 for the tension rod, first mount 170 for the tension rod,
andl the main mount 122 form an elastic mount for the front side body mounting
portion 120.
The rear side elastic mount 24 in the rear side body mounting portion 140 is
the
same as that in the previous embodiment, in which a mount rubber 150 is fitted
in a
mounting hole 141 formed in the rear side body mounting portion 140 just as
shown in
Fig. 11, and therefore, the detailed explanation thereof is omitted.
The tension rod (160, 170, 171) is thus located near the extension of the belt
line. of the V-belt 63, so that the engine 25 is allowed to be turnable around
the
connecting portion between the first mount 170 and the front side body
mounting
portion 120 and the connecting portion between the second mount 171 and the
supporting plate 126 and to be restricted in the longitudinal direction. At
the same
time, the rear side elastic mount 24 in the rear side body mounting portion
140 is
elastically deformed to mainly absorb the movement of engine 25 in the radial
direction. As a result, vibration of the entire engine 25 can be absorbed by
the rear side
ela;>tic mount 24 and is not transmitted to the body side.
Further, the twisting due to vibration of the engine 25 can be restricted by
the
tension rod (160, 170, 171), and the main mount 122 can be used commonly to
the
mount rubber 150 of the rear side elastic mount 24.
Next, a further embodiment of the engine supporting structure will be
described
with reference to Fig. 14. Fig. 14 is similar to Fig. 13, except that a front
side body
mounting portion 120 has a supporting structure which is turnable through a
collar and
a h~~nger shaft.
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A rear side body mounting portion 140 has the same structure as that shown in
Fig;. 13. That is, a rear side elastic mount 24 is formed of a mount rubber
150, and is
disposed on the body of the engine 25 in the same layout as shown in Fig. 2..
The front side body mounting portion 120 is disposed between the right and
left down-tubes 21. A cylindrical hanger shaft 180 is inserted in a through-
hole 121
formed in the front side body mounting portion 120 in the width direction of
the body.
Both ends of the hanger shaft 180 are aligned with through-holes 181 formed in
lower
end portions of the down-tubes 21. Then, a long-sized bolt 182 is inserted in
the
thr~~ugh-hole 181 on one side, passing through the hanger shaft 180, and
projects from
the through-hole 181 on the other side. The projecting end portion of the bolt
182 is
secured with a nut 183. Thus, the front side body mounting portion 120 is
mounted to
the body side.
Outer peripheral portions of both end portions of the hanger shaft 180 are
brought into sliding-contact with collars 185 fitted in large-diameter holes
184 formed
at both ends of the through-hole 121, so that the front side body mounting
portion
120, that is, the engine 25 is turnable around the engine hanger shaft 180.
Further, since the right and left end portions of the front side body mounting
portion 120 are separated from the right and left down-tubes 21 with slight
gaps 186
put therebetween, the engine 25 is easily turnable. In addition, a radial gap
187 is
fonmed between each collar 185 and the hanger shaft 180.
Accordingly, although the front side body mounting portion 120, that is, the
engine 25 is not elastically supported to the body, it can be moved around the
hanger
shaft 180 in the rotational direction because the rear side body mounting
portion 140 is
mounted on the body side through the mount rubber 1 S0.
The engine 25 is thus moved only in the rotational direction around the hanger
shaft 180 and is restricted in the longitudinal direction. At the same time,
the rear side
body mounting portion 140 allows the engine 25 to be moved in the radial
direction
with the mount rubber 1 SO being deformed, to thereby absorb the vibrations of
the
engine.
Further, since the movement of the front portion of the engine 25 is reduced,
the sealing performance at a connection portion between the cylinder portion
26 and
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the exhaust pipe 37 mounted at the front portion thereof (see Fig. 2) can be
kept
desirable for a long period of time.
Additionally, since the mounting position of the hanger shaft 180 is located
near the extension of the action line A connecting the centers of the drive
pulley 62 and
the driven pulley 64 to each other (see Fig. 5), the movement of the engine 25
due to
the drive reaction force can be further reduced.
It should be noted that the present invention is not limited to the above
embodiments, and many changes and variations may be made without departing
from
the scope of the present invention. For example, the mount in the front side
body
mounting portion 120 shown in Fig. 2 may be replaced from the mount rubber 150
to
the ring bushing 130, and the tension rod may be replaced from the connecting
plate
160 shown in the previous embodiment to a connecting round rod.
With respect to the front and rear body mounting portions 120 and 140, the
front and rear side elastic mounts 23 and 24 may be not directly fitted to the
crank case
27. For example, these mounts may be disposed between the engine 25 and the
vehicular body; mounting members may be provided extending from these mounts
to
the body and the engine; and the engine side mounting member may be supported.
The invention being thus described, it will be obvious that the same may be
varied in many ways. Such variations are not to be regarded as a departure
from the
spirit and scope of the invention, and all such modifications as would be
obvious to
one skilled in the art are intended to be included within the scope of the
following
claims.
