Motor vehicles – Including one or more ski-like or runner members – With at least one surface-engaging propulsion element
Reexamination Certificate
1998-11-24
2001-05-22
Johnson, Brian L. (Department: 3618)
Motor vehicles
Including one or more ski-like or runner members
With at least one surface-engaging propulsion element
Reexamination Certificate
active
06234264
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to suspension systems. More specifically, the present invention is concerned with a snowmobile suspension system.
BACKGROUND OF THE INVENTION
It is well known in the art to suspend the drive belt of a snowmobile below the body thereof for suspension movements.
These suspension systems are usually provided with a pair of side rails to guide the drive belt, a pair of suspension arms each having a proximate end pivotally mounted to the snowmobile and a distal end pivotally mounted to both side rails. The side rails, suspension arms and the snowmobile are so configured as to form a deformable parallelogram, thereby allowing suspension movements of the side rails with respect to the snowmobile between a fully extended and a fully retracted position. Shock absorbers and compression springs are also provided between the side rails and the snowmobile to bias the side rails towards their extended position.
Such conventional snowmobile suspension systems suffer from many drawbacks. A first drawback relates to the material used to make the side rails. Indeed, side rails are usually made of aluminum which yields relatively heavy and complicated to manufacture side rails. Furthermore, aluminum side rails have other drawbacks related to the nature of the material such as, for example, poor resistance toughness and low fatigue life.
A second drawback of the conventional snowmobile suspension systems is revealed when a force, overcoming the forces applied by the shock absorbers and the springs, causes the side rails to go from their fully extended position to their fully retracted position. When this is the case, the side rails will hit the underside of the snowmobile, which may damage the vehicle and/or endanger the driver.
To overcome this drawback, commercially available snowmobile suspension systems are provided with a piece of resilient material, for example, rubber, strategically positioned to intercept the side rails before they contact the underside of the snowmobile. The contact is therefore much less violent since the resilient material absorbs a portion of the energy of the impact. However, the contact between the side rails and the rubber piece still causes undesired sensations to the driver.
A third drawback is the lack of adjustability of the suspension characteristics or the complexity of adjustment of these characteristics. Indeed, conventionally, the pivotal attachments securing the distal end of the rear suspension arm to the side rails and the shock absorbers to the side rails are at predetermined fixed positions which results, for a given configuration, in predetermined suspension characteristics. This is a drawback since it removes the possibility for the driver to select different suspension characteristics for different type of rides.
To address this problem, many adjustable snowmobile suspension systems have been proposed. For example, U.S. Pat. No 5,692,579 issued on Dec. 2, 1997, naming Keith W. Peppel et al. as inventors and entitled “Adjustable Snowmobile Track Suspension” discloses a system provided with a rear suspension arm having a distal end which is so mounted to the side rails that limited longitudinal movements of the distal end may be achieved. The systems also include adjustable limits allowing the characteristics of the suspension to be adjusted by the user.
While Peppel's suspension is an improvement in terms of adjustability, it involves many mechanical elements to allow the longitudinal movements and to limit these movements. Furthermore, the user needs some tools to loose the fasteners, rotate the rectangular limits and to tighten the fasteners.
OBJECTS OF THE INVENTION
An object of the present invention is therefore to provide an improved snowmobile suspension system.
SUMMARY OF THE INVENTION
More specifically, in accordance with the present invention, there is provided a snowmobile suspension system configured to suspend a drive track to a snowmobile; the suspension system comprising:
a front suspension arm having a proximate end pivotally mounted to the snowmobile; the front suspension arm having a distal end;
a rear suspension arm having a proximate end pivotally mounted to the snowmobile; the rear suspension arm having a distal end;
a pair of side rails; each side rail being pivotally mounted to the distal ends of the front and rear suspensions for suspension movements between a retracted position where the side rails are adjacent to the snowmobile and an extended position; each side rail being made of composite material and provided with a concave undersurface; and
a biasing assembly pivotally mounted to the snowmobile and to both side rails; the biasing assembly biasing both side rails towards the extended position.
According to a second aspect of the present invention, there is provided a a snowmobile suspension system configured to suspend a drive track to a snowmobile; the suspension system comprising:
a front suspension arm having a proximate end pivotally mounted to the snowmobile; the front suspension arm having a distal end;
a rear suspension arm having a proximate end pivotally mounted to the snowmobile; the rear suspension arm having a distal end;
a pair of side rails; each side rail being pivotally mounted to the distal ends of the front and rear suspensions for suspension movements between a retracted position where the side rails are adjacent to the snowmobile and an extended position;
a biasing assembly pivotally mounted to the snowmobile and to both side rails; said biasing assembly biasing both side rails towards the extended position; and
a progressive spring assembly so mounted to the pair of side rails as to contact at least one of the front and rear suspension arms when the pair of side rails nears the retracted position thereby absorbing excess energy from the side rails to prevent forceful contact between the side rails and the snowmobile.
According to a third aspect of the present invention, there is provided a a snowmobile suspension system configured to suspend a drive track to a snowmobile; the suspension system comprising:
a front suspension arm having a proximate end pivotally mounted to the snowmobile; the front suspension arm having a distal end;
a rear suspension arm having a proximate end pivotally mounted to the snowmobile; the rear suspension arm having a distal end;
first and second longitudinal side rails; each longitudinal side rail being pivotally mounted to the distal end of the front suspension arm; each longitudinal side rail having a generally transversal rear pivotal axis and a semi-circular channel coaxial with the rear pivotal axis; the semi-circular channel having opposite ends;
a linkage assembly connecting the distal end of the rear suspension arm to the pair of side rails; the linkage assembly including, for each side rail:
an adjustable cam assembly so mounted to the side rail as to pivot about the rear pivotal axis; the cam assembly having an off-center arm mounting aperture to which the distal end of the rear suspension arm is pivotally mounted; and
at least one adjustable abutment element so mounted to the cam assembly as to extend in the semi-circular channel; the abutment element limiting the pivoting movements of the cam assembly by abutting the ends of the semi-circular channel; and
a biasing assembly pivotally mounted to the snowmobile and to both side rails; the biasing assembly biasing both side rails towards an extended position.
Other objects, advantages and features of the present invention will become more apparent upon reading of the following non restrictive description of preferred embodiments thereof, given by way of example only with reference to the accompanying drawings.
REFERENCES:
patent: 3719242 (1973-03-01), Duclo
patent: 3913692 (1975-10-01), Lohr et al.
patent: 4987965 (1991-01-01), Bourret
patent: 5265692 (1993-11-01), Mallette
patent: 5301965 (1994-04-01), Floreani
patent: 5370198 (1994-12-01), Karpik
patent: 5667031 (1997-09-01), Karpik
patent: 5692579 (1997-12-01), Peppel et al.
patent: 5730242 (1998-03-0
Boivin Alain
Boivin Denis
A & D Boivin Design
Goudreau Gage Dubuc
Johnson Brian L.
Winner Tony
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