Motor vehicles – Including one or more ski-like or runner members – With at least one surface-engaging propulsion element
Reexamination Certificate
1998-05-26
2001-03-13
Boehler, Anne Marie (Department: 3618)
Motor vehicles
Including one or more ski-like or runner members
With at least one surface-engaging propulsion element
C180S186000, C280S016000, C280S028000
Reexamination Certificate
active
06199649
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a steering and suspension system for typical motorized snowmobiles in use for recreational purposes, and particularly to improving the maneuverability and safety of such snowmobiles.
2. Description of the Prior Art
The typical snowmobile used for recreational purposes today is not much different from the original recreational snowmobile developed by Armand Bombardier. The recreational snowmobile is propelled by a rear mounted cleated endless rubber track powered by a gasoline engine and steered by two forward mounted parallel skis. The driver turns the snowmobile by using a handlebar connected through a linkage to turn the skis in a parallel fashion with respect to the drive track. The uncertain footing provided by snow and ice make it difficult to control the typical snowmobile especially when travelling at speed. The ski suspension typical of early snowmobiles consisted of a downwardly arched leaf spring mounted on a typical ski such that the steering connected to and turned the leaf spring and consequently the ski, the leaf spring arching to provide cushioning to the ride and keeping the ski in contact with the snow. This type of suspension had very limited vertical travel and did not support the ski with much precision. Newer telescoping type ski suspension as described by West in U.S. Pat. No. 4,143,729 and Blanchard in U.S. Pat. No. 4,826,185 increased the usable vertical travel and provided integral damping means and better control of the ski. The most common type of ski suspension now in use is described by Talbot in U.S. Pat. No. 4,671,521. The trailing arm support with parallel transverse arms provides for excellent ski stability when turning and excellent vertical travel with a strong, relatively simple design. The transverse suspension arms are centrally mounted on the snowmobile and move the skis vertically in an arc instead of a straight line. This lateral ski displacement during compression of the ski suspension in conjunction with a relatively stable steering rod linkage causes the skis to toe out on compression of the suspension resulting in erratic steering or “bump steer”. Current steering and suspension systems mount the ski axially about the vertical central turning point of the ski and support the snowmobile front end on the same point. The driver must shift his weight toward the inside of a turn to prevent the snowmobile from rolling over. This shift is necessary to bring the center of gravity of the driver —snowmobile combination closer to the inside turning arc to balance centrifugal cornering force with gravity to prevent rollover. Unpredictable footing on snow can often make this feat impossible and accidents occur, particularly for drivers not skilled in this type of maneuver. Prior snowmobile suspensions have been functional only in supporting the weight of the snowmobile by applying pressure to the skis and providing a laterally stationary bearing for ski rotation. Steering on prior snowmobiles has been by rotation of the ski about its center of support at the ski leg, providing the same level of lateral support on both sides of the snowmobile during cornering.
The skis on current snowmobiles generally have a keel on the bottom running surface which is approximately equal in length both forward and aft of the center of the ski in order to maintain ease of steering.
Snowmobiles by nature of their generally light weight and recreational use have very little in the way of safety features. Frontal collisions by snowmobiles almost always result in serious injury to the driver since there is no energy absorbing barrier between the driver and the object being struck.
SUMMARY OF THE INVENTION
It is the aim of the present invention to provide a snowmobile steering and suspension mechanism which laterally shifts the support of the skis toward the outside of the turning arc during cornering, thereby providing additional outboard support for the snowmobile and reducing the tendency of the snowmobile to roll over. It is a further aim of the present invention to provide a snowmobile steering and suspension mechanism which applies increased support pressure to the outboard ski of the snowmobile during cornering to further stabilize the snowmobile and prevent roll over. It is a further aim of the present invention to provide a snowmobile steering and suspension mechanism which shifts the center of gravity of the snowmobile toward the inside of the turning arc of the snowmobile to improve cornering stability. It is a further aim of this invention to provide a steering mechanism for a snowmobile that positions the driver's weight toward the inside of a turning arc of a snowmobile. It is a farther aim of the present invention to provide a steering mechanism that absorbs and redirects the impact energy of a snowmobile driver colliding with the steering handlebar during a frontal impact of the snowmobile.
The embodiment of this invention in a snowmobile is characterized by the dual function of the suspension arms and suspension spring as rotatable steering members. The suspension arms are linked to the snowmobile frame by a rotatable suspension mounting at the front frame of the snowmobile on generally vertical support bearings. Turning of the handlebar on the steering column moves the left and right steering control rods longitudinally which correspondingly rotate the rotatable suspension mountings. The rotatable suspension mountings rotate the suspension arms in an arc about the generally vertical support bearings. The ski leg bearing supports, ski legs and skis, supported by the suspension arms connected in this manner rotate about the generally vertical support bearings, becoming angular to the direction of travel of the snowmobile and causing it to turn. The weight supporting bottom area of the ski does not rotate about its central point, at approximately its ski leg location, but rotates about a center forward of the center of the supporting area of the ski, resulting in lateral displacement of the ski supporting area toward the outside of the turning arc of the snowmobile. The angle of the suspension arms and connected skis with respect to the line of forward motion of the snowmobile determine the turning radius of the snowmobile. The turning radius of the snowmobile can be decreased further rotating the ski by its ski leg within its ski leg support bearing concurrently with the rotation of the rotatable suspension mounting. A control arm, mounted on its inboard end to the rotatable ski leg within its ski leg support bearing, has its outboard end held equidistant to a frame of the snowmobile by a swivel mounted control rod to maintain the position of the control arm outboard end laterally equidistant from the snowmobile during steering movement of the suspension arms and ski leg radially around the frame mounted generally vertical support bearing. The lateral movement of the ski leg with respect to the frame of the snowmobile causes the control arm to rotate the ski leg and ski about the ski leg ski leg support bearing resulting in greater angularity of the ski with respect to the snowmobiles line of forward motion.
In the preferred embodiment of the invention the frame mounted generally vertical support bearing supporting the rotatable suspension mounting is given a positive camber angle to tilt the plane of rotation of the suspension arms downwardly outboard of the snowmobile thus increasing downward support pressure on the outboard side of a turning arc and reducing downward support pressure on the inboard side of the turning arc and further stabilizing the snowmobile during turning.
In the preferred embodiment, the steering column is downward angled to the front of the snowmobile and provides a straight line connection from the front of the snowmobile to the driver. The energy of a frontal impact to the snowmobile is absorbed in part by a deformable energy absorbing section of the steering column. A similar parallel impact absorbing column is forward mounted to the
Arctek Inc.
Boehler Anne Marie
LandOfFree
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