Note: Descriptions are shown in the official language in which they were submitted.
211338S
SUSPENSION DEVICE FOR A SNOWMOBILE
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a suspension device
for a snowmobile which is propelled on snow by use of a
crawler belt.
Description oflBackground Art
For the snowmobile which is propelled on a snow
surface b.y use of a crawler belt, it is necessary to
resiliently support the body. For this purpose, in the
past, the slide rail for pressing the crawler belt against
the snow surface is pivotally supported on the rear lower
end of the swing arm having the front upper end swingingly
supported on the body frame. In addition, the suspension
spring is vertically disposed between the slide rail and
the body frame.
However, since the snowmobile has a small vertical
space for positioning the suspension spring in the
construction, a sufficient buffer effect cannot be
exhibited.
.
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In view of the above, Japanese Patent Publication No .
58-50914 discloses a construction in which a rear cushion
unit comprised of a hydraulic buffer and a suspension
spring is disposed in a horizontal direction within a
space surrounded by a crawler belt so that the vertical
movement of a slide rail as the snowmobile runs is
converted into a horizontal movement through a link to
transmit the horizontal movement to the rear cushion unit.
In the suspension device disclosed in the
aforementioned Japanese Patent Publication No. 58-50914,
both the front end and the rear end of the rear cushion
are connected to the slide rail through the link.
Therefore, the weight of the rear cushion is added as a
lower load of a spring and the fallibility relative to the
snow surface is lowered.
OBJECTS AND SUMMARY OF THE INVENTION
The present invention has been achieved for the
purpose of enhancing the fallibility of the snowmobile
relative to the snow surface. To this end, the present
invention provides a suspension device for a snowmobile,
which resiliently supports a snowmobile body relative to
a slide rail which presses a crawler belt against a snow
surface.
A suspension device for a snowmobile is provided
wherein the slide rail is pivotally mounted on a rear
lower end of a swing arm having a front upper end
swingingly supported on a frame on the snowmobile body
side. A front upper end of a rear cushion unit includes
a hydraulic buffer and a suspension spring
swingingly supported in the vicinity of the front upper
end of said swing arm, and a rear lower end of said rear
cushion is connected to a link constituting a progressive
link mechanism pivotally supported on the swing arm.
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The vertical movement of the slide rail as the
snowmobile is propelled on a snow surface is converted into an
oblique angle, near a horizontal, in the movement to transmit it
to the rear cushion unit. As the slide rail assumes an upward
position, the transmission speed increases. As a result, a
great attenuation force is produced and the displacement changes
in a so-called progressive manner.
According to a broad aspect of the invention there is
provided a suspension device for a snowmobile for resiliently
supporting a snowmobile body comprising:
a frame for supporting the snowmobile body;
a slide rail operatively connected to said frame for
pressing a crawler belt against a snow surface;
a swing arm having a front upper end pivotally
supported on said frame and a rear lower end pivotally mounted
on said slide rail; and
a rear cushion unit having a hydraulic buffer and a
suspension spring, said rear cushion unit including a front
upper end pivotally supported adjacent to the front upper end of
said swing arm, and a rear lower end of said rear cushion unit
connected to said frame through a progressive link means
pivotally supported on the swing arm.
According to another broad aspect of the invention
there is provided a suspension device for providing a resilient
support for a snowmobile body comprising:
a frame for supporting the snowmobile body;
a slide rail operatively connected to said frame for
pressing a crawler belt against a snow surface;
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a swing arm having a first end pivotally supported on
said frame and a second end pivotally mounted on said slide
rail;
a shock absorber including a first end pivotally
supported on a shaft adjacent to the first end of said swing
arm, and a second end of said shock absorber being connected to
said frame through a progressive link means pivotally supported
on the swing arm.
Further scope of applicability of the present
invention will become apparent from the detailed description
given hereinafter. However, it should be understood that the
detailed description and specific examples, while indicating
preferred embodiments of the 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 DRAWIN~S
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:
Figure 1 is a side view of the entire snowmobile to
which the suspension device according to the present invention
is applied;
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Figure 2 is a perspective view showing the inside of a
body cover of the snowmobile;
Figure 3A is an enlarged side view showing the
suspension device of the snowmobile and the periphery thereof;
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Figure 3B is an enlarged side view showing a second
embodiment of the suspension device of the snowmobile and
the periphery thereof;
Figure 4 is a view taken along A-A of Figure 3A;
Figure 5, right side, is a view taken along Bl-B1 of
Figure 3A, and Figure 5, left side, is a view taken along
B2-B2 of Figure 3A; and
Figure 6 is a view similar to Figure 3A showing
another embodiment.
PREFERRED EMBODIMENTS OF THE INVENTION
An embodiment of the present invention will be
described below with reference to the accompanying
drawings. Figures 1 and 2, are side views of the entire
snowmobile to which a suspension device according to the
present invention is applied. In the snowmobile, an upper
frame 2 is mounted on the front portion of a main frame 1
which includes a pipe. A floor 3 is formed with a passage
through which high temperature cooling water from a
radiator is passed and provided between a rear portion of
the upper frame 2 and a rear end of the main frame 1. A
head pipe 4 is mounted on the front end of the main frame
1 and the upper frame 2.
An engine 5 is mounted in a space surrounded by the
main frame 1 and the upper frame 2. A transmission case
6 is disposed at the rear of the engine 5. An air cleaner
7, a carburetor 8 and a fuel tank 9 are arranged above the
transmission case 6, and a muffler 10 is mounted on the
front side of the head pipe 4. All of the above members
are covered by a body cover 11.
As illustrated in Figure 1, a grip portion 90
protrudes from both sides of the body cover 11, and a grip
portion 91 is also provided at the rear end of the floor
3.
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A steering post 21 is inserted into the head pipe 4.
A steering shaft 23 is connected to the upper end of the
steering post 21 through a universal joint 22. A
handlebar 25 is connected to the upper end of the steering
shaft 23 through a universal joint 24. A steering link 26
includes a lower end supported on the body side of the
snowmobile so that the steering link 26 may be moved
within a vertical area disposed frontwardly of and
parallel with the steering shaft 23. A bracket 27 of the
handlebar 25 is connected to the upper end of the steering
link 26. The steering shaft 23, the handlebar 25 and the
steering link 26 constitutes a parallel link mechanism, so
that even when the position of the handlebar 25 is moved
up and down according to the riding position of an
operator P, an angle of inclination of the handlebar is
always maintained to be constant.
As illustrated in Figures 1 and 2, a front ski 31 for
steering the snowmobile is mounted on the lower end of the
steering post 21 through links 28, 29 and a bracket 30,
and an attitude of the front ski 31 is returned to its
straight direction by means of an biasing or urging member
32.
Next, the suspension device will be described with
reference to Figures 3A, 3B, 4 and 5. A shaft 40 is
mounted in an intermediate portion between left and right
main frames 1, 1. A cross pipe 41 is rotatably supported
on the shaft 40. Front ends of a pair of left and right
swing arms 42, 42 are swingingly supported on the cross
pipe 41. A shaft 43 is mounted in an intermediate portion
between the pair of swing arms 42, 42, and a triangular
link 44 is rotatably supported on the shaft 43.
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A front end of a rear shock absorber or cushion unit
45, including a hydraulic buffer 45a and a suspension
spring 45b, is connected to the center of the cross pipe
41 arranged between the front ends of the pair of left and
right swing arms 42, 42. That is, the front end of the
rear shock absorber or cushion unit 45 is supported on the
cross pipe 41 which is a part of the frame of the
snowmobile instead of the swing arm 42.
The rear end of the rear cushion unit 45 is connected
to one corner portion 44a of the triangular link 44. A
shaft 46 is mounted in the intermediate portion between
the left and right main frames 1, 1. A cross pipe 47 is
rotatably supported on the shaft 46. An upper end of a
link 48 is mounted on the cross pipe 47, and a lower end
of the link 48 is connected to the other corner portion
44b of the triangular link 44.
Gusset plates 50, 50 are provided in the vicinity of
a cross portion between the main frame 1 and the upper
frame 2, as shown in Figure 5. A driving shaft 51 is
rotatably supported between the gusset plates 50, 50. A
sprocket 52, connected to an output shaft of the
transmission 6 by a chain, is secured to one end of the
driving shaft 51. A driving wheel 53 is mounted by means
of a spline fitting or the like on the intermediate
portion of the driving shaft 51, and a gear portion formed
in the outer periphery of the driving shaft 53 is brought
into engagement with a rugged portion formed in the inner
side of the crawler belt 54.
The driving force of the engine 5 is transmitted to
a drive pulley 70 of a belt converter as shown in Figure
2. A belt 72 extends between the drive pulley 70 and a
driven pulley 71. The rotation of the driven pulley 71 is
transmitted to an idle shaft 73, and the rotation of the
idle shaft 73 is transmitted to the sprocket 52 through a
chain 74.
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A brake disk 75, as illustrated in Figure 5, is
secured to the end of the driving shaft 51 on the side
opposite to the sprocket 52, and a brake caliper 76 is
provided, as shown in Figure 3, in the vicinity of the
brake disk 75.
On the other hand, a collar 55 is provided between
rear ends of the left and right swing arms 42, 42. A
shaft 56 is rotatably mounted in the collar 55. A main
slide rail 57 extends in a lateral direction and is
mounted in the central portion of the shaft 56 having a
large diameter. A pair of left and right side slide rails
58, 58 are mounted on the outer end of the shaft 56 having
a small diameter.
A guide wheel 59 is rotatably supported internally
from the side slide rail 58 of the shaft 56. A spring 60
is provided for downwardly urging the front end of the
main slide rail 57 disposed internally of the guide wheel
59. A shaft 61 is mounted between the main slide rail 57
and the front end of the side slide rail 58. A guide
wheel 62 is rotatably supported on the shaft 61. A shaft
63 is mounted between the main slide rail 57 and the rear
end of the side slide rail 58, and a guide wheel 64,
having a larger diameter relative to the diameter of the
guide wheel 62, is supported on the shaft 63 so that the
guide wheel 64 can be adjusted in position and rotatably
supported.
The guide wheels 59, 62 and 64 are fitted into a
groove 65 formed in the inner surface of the crawler belt
54. A slight clearance is formed between the lower
surface of the main slide rail 57 and the inner surface in
the center of the crawler belt 54, and a slight clearance
is formed between the lower surface of the side slide rail
58 and a protrusion 66 formed in the outer end widthwise
of the crawler belt 54.
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With the above-described arrangement, when the engine
5 is driven, the driving wheel 53 rotates, and the crawler
belt 54 is moved by the rotation of the driving wheel 53
so that the snowmobile is propelled. When the main slide
rail 57 and the side slide rail 58 move up and down as the
snowmobile is propelled, the swing arm 42 swings up and
down around the shaft 40.
When the swing arm swings upward from the state shown
- in Figure 3A, the triangular link 44 swings in a clockwise
direction around the shaft 43 to compress the hydraulic
buffer 45a and as a result the attenuation force is
generated. As the positions of the slide rails 57 and 58
become higher, the amount of rotation of the triangular
link 44 increases so that the compression speed of the
hydraulic buffer 45a becomes higher and the attenuation
force produced also increases. That is, as the swing arm
42 swings upward, there is established a progressive link
mechanism which gradually increases its attenuation force.
In another embodiment of the present invention, as
illustrated in Figure 3~, a pair of left and right shock
absorbers or dampers 115 are interposed between the main
frame 1 and the shaft 61, to define the swinging range of
a combination of the main slide rail 57, the side slide
rail 58 and guide wheels 59, 62 and 64, thus improving the
controllability.
Figure 6 is a view similar to Figure 3A illustrating
a further embodiment. The same members as those
previously described are indicated by the same reference
numerals, description of which is omitted. While in the
above-described embodiment, the triangular link 44 is
directly connected to the swing arm 42 through the shaft
43, it is to be noted that in this embodiment, another
link 49 is connected to the swing arm 42 through the shaft
43. The upper end of the link 49 is connected to a corner
portion 44c of the triangular link 44.
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By the provision of the arrangement as described
above, it is possible to provide the snowmobile with an
adequate progressive characteristic.
While in the above embodiment, a progressive link
mechanism has been shown in which as the slide rail
assumes an upper position. The transmission speed of the
rear cushion unit increases to generate a large
attenuation force. It is to be noted that the internal
construction of the hydraulic buffer may be made of a
stroke position dependent type to thereby vary the
attenuation force produced.
As described above, according to the present
invention, it is possible to convert a small vertical
movement of the slide rail into a large horizontal
movement to transmit it to the rear shock absorber or
cushion unit. In addition, the front upper end of the
rear shock absorber or cushion unit is connected to the
frame side of the snowmobile body. Therefore, the weight
of the rear cushion unit is not added to the lower load of
the spring to enhance the fallibility relative to the snow
surface.
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.
