Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates to a travelling vehicle
such as a snowmobile or the like and more particularly to a
vehicle wherein the grounding load distribution between front
and rear can be changed by shifting of the driver's weight.
A travelling vehicle of the type to which this
invention relates is disclosed in the form of a snowmobile in
Japanese Patent Publication No. 50914/1983. In this known
snowmobile, a steering sledge is connected to a lower front part
of the snowmobile body through a plate spring, while a driving
device in the form of an endless track is connected to a lower
rear part of the same body, through a suspension system, to a
power unit. A seat is mounted on the snowmobile body, and a
driver sitting on the seat steers the sledge using a handle,
while the endless track is driven by the power unit, thereby
allowing the snowmobile to travel.
In the above conventional snowmobile, however, since
the steering sledge which constitutes a front steering portion
contacts the ground at a load proportional to a load distribution
ratio between it and the track of the driving device at the rear
portion, the sledge is apt to sink into snow when travelling on
a weak surface such as fresh snow, resulting in increased
travelling resistance.
An object of the present invention is to provide a
travelling vehicle capable of travelling lightly even on a weak
road surface without substantially increasing its travelling
resistance.
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According to the present invention, a travelling
vehicle comprises a vehicle body, a steering portion,
including a steering handle and a grip portion in a front part
of the vehicle body, a drive means pivotably supported at a
rear part of the vehicle body for vertical movement, a shock
absorbing unit interposed between the drive means and the
vehicle body, and a power unit connected for power
transmission with the drive means, said power unit being
disposed forward of the pivoted portion of the driving means
to the vehicle body, characterized in that the vehicle body is
provided with a generally flat elongate riding portion
extending rearwardly of a line L1 connecting the grip portion
of the steering handle with a grounding point at the rearmost
end of the drive means to a position rearwardly of said
grounding point, and said shock absorbing unit is connected to
the vehicle body in a position forward of the line Ll, said
riding portion being adapted to support a standing driver at
different locations including a location rearwardly of said
grounding point and a location at least as far forward as the
position at which the shock absorbing unit connects to the
vehicle body.
In one embodiment the steering handle is tiltably
supported by the vehicle body for tilting movement in the
longitudinal direction of the vehicle body, and there is
provided a biasing means for urging the steering handle to a
predetermined stand-up or neutral position.
In the travelling vehicle according to the
invention, when the driver puts his feet on the riding portion
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and shifts his weight backward, the center of gravity of the
vehicle also shifts backward to reduce the grounding load of
the steering portion in the front part of the vehicle body.
Thus improvements in rear wheel travelling and trick riding
characteristics are achieved.
When the riding portion extends to the rear of the
grounding point at the rearmost end of the driving device, it
is possible to shift the vehicular center of gravity backward
to a greater extent.
When the steering handle is tiltably supported for
tilting movement in the longitudinal direction of the vehicle
body and a biasing means is provided for urging the steering
handle to a predetermined stand-up or neutral position, the
driver can easily grasp the handle grip, even with his feet at
the very rear of the foot portion. Since the steering handle
is urged to a predetermined stand-up position, it is possible
to suppress the tendency of the steering handle to wobble
during normal travelling of the vehicle.
In drawings which illustrate embodiments of the
invention:
Figure 1 is a schematic side view of a travelling
vehicle according to a first embodiment of the present
invention;
Figure 2(a) is an enlarged side view of a part of
the steering mechanism;
Figure 2(b) is an enlarged sectional view along the
line C-C in Figure 2(a);
Figure 3(a) is a side view of a travelling vehicle
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according to a second embodiment of the present invention;
Figure 3(b) is a plan view of the travelling vehicle
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of Figure 3 (a) ;
Figure 4 is a perspective view of a travelling
vehicle according to a third embodiment of the present invention;
Figure 5 is a side view of the vehicle of Figure
4;
Figure 6 is a plan view of the vehicle of Figure 4;
Figure 7 is a front view, partially in section, of a
principal portion of the vehicle of Figure 4;
Figure 8 is a partially enlarged partially sectional
view showing another embodiment of the principal portion of
Figure 7; and
Figure 9 is a side view of a travelling vehicle
according to a fourth embodiment of the present invention.
Figures 1 and 2 illustrate a first embodiment of the
present invention, of which Figure 1 is a schematic side view of
a travelling vehicle in the form of a snowmobile, Figure 2(a) is
a partially enlarged side view of a detail thereof, and Figure
2(b) is a partially enlarged sectional front view of the detail.
In Figure 1, the numeral 11 denotes a generally flat
plate-like body, and a planar riding portion lla comprises
substantially the whole upper surface of the body 11. As
schematically shown in the figure, a driver M gets on the riding
portion lla in a standing posture in such a manner that his feet
can be placed on a rear end part of the riding portion lla. The
rear end part of the riding portion lla comprises a foot portion
77.
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To a front end of the body 11 is fixed a head tube
12, into which is rotatably inserted a steering shaft 13. A
steering handle 14 is fixed to an upper end of the steering shaft
13, while a steering member in the form of a ski 16 is mounted
to a lower end of the steering shaft 13. The ski 16 is vertically
movable through a trailing link mechanism 15. The steering shaft
13 has a biasing mechanism 5 at the lower end thereof, and the
ski 16 is moved pivotally about the steering shaft 13 by the
operation of the steering handle 14. Although the details are
here omitted, the link mechanism 15 incorporates a cushion spring
15a therein, which urges the ski 16 downwards toward the travel-
ling surface.
As shown in Figures 2(a) and (b), the biasing
mechanism 5 comprises a square-section shaft 115 fixed to a
steering shaft 15a of the link mechanism 15, an outer casing 113
mounted to a joint plate 13a at a lower portion of the steering
shaft 13, and four biasing rubber pieces 5a disposed between the
square-section shaft 115 and the outer casing 113. The biasing
mechanism 5 generates a restoring force against torsion between
the square-section shaft 115 and the outer casing 113, for shift-
ing the steering shaft 13 back to a neutral position A as
illustrated in Figure 1.
A power unit 17 is mounted to the body 11 behind the
head tube 12, and a driving device 18 is suspended from a lower
portion of the body 11 behind the power unit 17_ As is well
known, the power unit 17 comprises an engine and a transmission
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both mounted integrally with each other. An output shaft of the
transmission is connected to the driving device 18 in a power
transferable manner through a chain 19.
In the driving device 18, a driving wheel 20 and a
floating wheel 21 are supported by the lower portion of the body
11 pivotably in longitudinally spaced relation to each other
through a holder 23. An endless crawler belt 22 is entrained
about both wheels 20 and 21. Between an intermediate part of
the holder 23 and the body 11 is interposed a shock absorbing
unit 24. The driving wheel 20 is connected to the power unit 17
through chain 19. The crawler belt 22 contacts the ground over a
large area and is driven by the power unit .17 to generate a
driving force.
In the snowmobile of this first embodiment, the
riding portion lla is formed on the body 11, and the rear part of
the riding portion lla has the foot portion 77 extending rearward-
ly beyond a line L1 through the handle grip 14a and a grounding
point at the rearmost end of the crawler belt 22. The driver M
can stand up on the riding portion lla. Specifically, the driver
M can place his feet on the foot portion 77 located in a position
rearwardly of the line Ll and ride the snowmobile in a standing
posture. The forces indicated by arrows in Figure 1 are exerted
on the body 11. Therefore, as the driver M moves in the longi-
tudinal direction as indicated by solid and chain lines in the
same figure, the center of gravity of the entire vehicle shifts in
the same direction. A moment around a transverse axis is
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generated in the body 11, whereby it is possible to adjust the
distribution of the grounding load between the ski 16 and the
crawler belt 22 of the driving device 18.
More particularly, in this snowmobile, when the
driver M moves forward (solid line), the grounding load of the
ski 16 can be increased, while when the driver moves backward
(chain line), it is possible to decrease the grounding load of
the ski. Thus, it is easy to change the load distribution. In the
case where the snowmobile travels on fresh snow, the driver M
moves backward as indicated by the chain line to decrease the
grounding load of the ski 16, whereby the ski can be prevented
from sinking into the fresh snow.
Figure 3 illustrates a travelling vehicle according
to a second embodiment of the present invention, in which Figure
3(a) is a side view and Figure 3(b) is a plan view. In this
second embodiment, the same elements as in the above first embodi-
ment are identified by the same reference numerals and explana-
tion thereof will be omitted.
In the second embodiment, a front wheel 31 is
provided in place of the ski used in the first embodiment, and
there is used a driving device 18 having three roller-like wheels
34a, 34b and 34c.
In the driving device 18, a wheel holder 33 is
mounted to a rectangular, pivotable frame 32 supported pivotably
by the body 11, and the three wheels 34a, 34b and 34c are suppor-
ted by the wheel holder 33. The holder 33 rotatably supports
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three axles 35a, 35b and 35c arranged longitudinally in the form
of a ladder, with the wheels 34a, 34b and 34c being fixed onto
those axles. A central part of the holder 33 is pivotably
supported by the pivotable frame 32 through a pivot shaft 36 with
the axle 35b coaxially inserted therein.
Onto the axle 35b are fixed a driven sprocket 36b
and two power transmitting sprockets 37a and 37b. Further, power
transmitting sprockets 38a and 38b are fixed onto the axles 35a
and 35c, respectively. A chain 19 is stretched between the driven
sprocket 36b and a driving sprocket 36a of the power unit 17.
Further, a chain 39a is stretched between the power transmitting
sprockets 37a and 38a, and a chain 39b between the power
transmitting sprockets 37b and 38b.
Also in this second embodiment, a riding portion lla
is formed on the body 11. The riding portion lla extends rear-
wardly beyond a line L1 through a handle grip 14a and a grounding
point of the rearmost end wheel 34c of the driving device 18.
A rear end part of the riding portion lla comprises a foot portion
77. Therefore, like the previous embodiment, the load distribu-
tion between the front wheel 31 and the driving device 18 can
be changed by a longitudinal movement of the driver M standing on
the riding portion lla.
Figures 4 to 8 illustrate a third embodiment of the
present invention, of which Figure 4 is a perspective view of a
snowmobile as a travelling vehicle, Figure 5 is a side view thereof,
Figure 6 is a plan view thereof, with some components of the
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snowmobile being removed, Figure 7 is a front view of a principal
portion thereof, and Figure 8 is a partially enlarged view showing
another mode of the said principal portion.
In those figures, the numeral 40 denotes a body of
the snowmobile. The body 40 comprises a main frame 41 of a
generally rectangular shape constituted by tubular members, and
a body member 42 of a synthetic resin or the like fixed to the
main frame 41. An upper portion of the body 40 comprises a riding
portion 40a which permits the driver M to stand thereon. A rear
end part of the riding portion 40a is bent upwards to form a
foot portion 77 over a predetermined length w of an upper surface
of the rear part. A power unit 43 is mounted to a front portion
of the body 40. The foot portion 77 is formed substantially flat
so that the driver can place his feet thereon, and it extends
rearwardly beyond a rear end of a driving device which will be
described later (see Figure 5).
The power unit 43 comprises an engine and a
transmission both mounted integrally with each other, and an upper
portion thereof is covered with a bonnet 44. In the power unit
43, an output shaft of the transmission is disposed below the
body 40, and a driving sprocket 45a is fixed to the transmission
output shaft and is connected to the driving device through a
chain 46. The bonnet 44 is fixed to a bonnet frame 47 erected on
the front portion of the body 40, and within the bonnet 44,
though not shown in detail, there are accommodated an air cleaner
52, a fuel tank 53, a battery 54 and a muffler 69 together with
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the power unit 43. The numeral 69a denotes an exhaust pipe.
A head tube 48 is fixed to a front end of the body
40, and a lower steering shaft 49 is rotatably inserted into the
head tube 48. To an upper end of the lower steering shaft 49 is
connected an upper steering shaft 55 tiltable in the longitudinal
direction through a universal joint 56, while a lower end of the
lower steering shaft 49 is connected to a ski 51 through a
trailing link mechanism 50 in the same manner as in the first
embodiment. The trailing link mechanism 50 includes a shock
absorber or cushion spring 50a disposed between the link
mechanism - lower steering shaft 49 connection and the link
mechanism - ski 51 connection. The numeral 51a denotes a handle
provided at a front end of the ski 51, and the numeral 80 denotes
a flexible boot for protection of the universal joint 56.
A steering handle 81 is fixed to an upper end of
the upper steering shaft 55, and a sleeve 59 is rotatably fitted
on the outer periphery of an intermediate portion of the upper
steering shaft. A pair of left and right stays 57L, 57R, are
mounted bridgewise between the sleeve 59 and the bonnet frame 47.
As shown in detail in Figure 7, the stays 57L and 57R are disposed
in between the sleeve 59 and the bonnet frame 47 and are connec-
ted through ball joints 58 to the sleeve 59 and the bonnet frame
47. The stays 57L and 57R prevent the upper steering shaft 55
from collapsing either to the right or to the left. Further,
coil springs 100L and 1008 are mounted to the stays 57h and 57R,
respectively, to generate a force for returning the steering
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shaft 55 to a neutral position A'.
The construction of the stays 57L and 57R is not
limited to the one described above. A construction such as that
shown in Figure 8 may be adopted. As illustrated in this figure,
a sleeve 59 is rotatably and axially slidably fitted on the upper
steering shaft 55, and one end of stays 57L and 57R is connected
to the sleeve 59 through ball joints 58, while opposite ends of
the stays 57L and 57R are connected with bolts 99 to the bonnet
frame 47 for pivotal movement about such bolts. Also in this
case, the upper steering shaft 55 is prevented from collapsing
either to right or left.
As shown in Figure 5, a pair of right and left
brackets 61 are suspended from the body 40, and a driving device
60 is pivotably supported by the brackets 61. In the driving
device 60, two floating wheels 64 and 65 are mounted rotatab)_y to
a wheel holding member 63 in front and rear positions, respective-
ly. The wheel holding member 63 is supported by a link 62 for
vertical movement. A driving wheel 66 is mounted to the brackets
61, and an endless crawler belt 67 is entrained about the floating
wheels 64, 65 and the driving wheel 66. The driving wheel 66 is
fixed to a rotary shaft (not shown) mounted bridgewise between
the brackets 66, and a driven sprocket 45b is fixed to the rotary
shaft. The chain 46 is stretched between the driven sprocket 45b
and the driving sprocket 45a, and the driving wheel 66 is thereby
driven by the power unit.
A torsion spring 68 is mounted to each of the
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brackets 61, and a front end of the wheel holding member 63 is
urged downward by the torsion springs 68. A lower end portion of
a shock absorber or cushion unit 70 is mounted to an upper portion
of the wheel holding member 63 in a position between the floating
wheels 64 and 65. An upper end of the shock absorber 70 is
mounted to a lower portion of the body 40. As in the first
embodiment, the mounted portion of the shock absorber 70 to the
body 40 is positioned ahead of the line L1 through the steering
handle 81 and the grounding point at the rearmost end of the
crawler belt 67.
In this third embodiment, the load distribution
between the ski 51 and the driving device 60 can be adjusted by
shifting of the weight of the driver M standing up on the riding
portion 40a of the body 40, and when the snowmobile travels on
fresh snow, the ski 51 can be prevented from sinking into the
snow by backward shift of the driver's weight.
In this third embodiment, the riding portion 40a is
extended rearwardly beyond a rear end of the driving device 60 to
form a foot portion 77 located behind the rear end of the driving
device rear end. Therefore, when the driver puts his feet on
the riding portion 77, an upwardly tilting moment for the front
portion of the body 40 can be increased and it is easy to reduce
the grounding load of the ski 51.
Figure 9 is a side view of a snowmobile as a
travelling vehicle according to a fourth embodiment of the
present invention, in which the same elements as in the third
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embodiment are identified by the same reference numerals and
explanation thereof will therefor be omitted.
In the fourth embodiment, a rear end of a body 40
is bent sharply upwards to form a stepped foot portion 77, so
that the foot portion 77 can be used as a seat. A hole is formed
in the foot portion 77 and a grip 97 is provided. Also, at a
front end of the body 40 there is also provided a grip 98.
In a driving device 60, an arm member 96 is mounted
bridgewise between a rotary shaft and a wheel holding member 63,
the rotary shaft being mounted between brackets 61, and a shock
absorber or cushion unit 70 is connected to the connection of arm
member 96 to the wheel holding member 63, while a cushion spring
95 is disposed between the arm member 96 and a front floating
wheel 64.
Further, a lower steering shaft 49 and an upper
steering shaft 55 are connected together tiltably by means of a
transversely extending connecting shaft 75 having rubber biasing
members which Generates a force for returning the steering shaft
55 to a neutral position A'.
In this fourth embodiment, since the foot portion
77 is formed in a stepped fashion on the body 40, the driver can
sit on the foot portion and thus a great degree of freedom can
be obtained in the riding posture.
Although snowmobiles have been illustrated in a number
of the embodiments, it will be apparent that the present invention
is applicable also to vehicles having normal tires.
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