Snowmobile CVT Inversion Reduces Angular Momentum
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Solution Overview
Problem
Snowmobile powertrains have high angular momentum, making it difficult to lean the vehicle for turning, especially in soft powdered snow, as all rotating parts rotate in the same direction, increasing the difficulty in overcoming this momentum for maneuverability.
Innovation Solution
The design incorporates a continuously variable transmission with a driving pulley and driven pulley rotating in opposite directions, along with a rotor that rotates about a laterally extending axis perpendicular to the snowmobile's longitudinal centerline, and a flexible mechanical element like a belt or chain to manage the angular momentum, allowing the rotor to counteract the momentum of the drive track and other components by rotating in the opposite direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If all rotating parts rotate in the same direction as the drive track, then the powertrain structure is simple and straightforward, but the total angular momentum increases making it difficult to lean the snowmobile for turning
Solution Approach 1:
The patent applies inversion by making the driving pulley rotate in the opposite direction to the drive track, while the driven pulley rotates in the same direction as the drive track. This creates opposing angular momentums that reduce the total angular momentum of the powertrain, enabling easier leaning and turning without complicating the overall powertrain structure.
2Ease of operation
If the driving pulley and driven pulley rotate in opposite directions, then the total angular momentum is reduced improving lean capability, but the torque transmission mechanism becomes more complex
Solution Approach 1:
The patent uses the driven pulley as a counterweight element that rotates in the same direction as the drive track, creating an opposing angular momentum to the driving pulley. This counterbalancing approach reduces total angular momentum and improves lean capability while maintaining a relatively simple torque transmission mechanism through the belt connection between pulleys.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration reduces the total angular momentum of the snowmobile's rotating parts, enhancing its ability to lean and turn by adjusting the rotor's speed to balance the momentum, improving maneuverability in various snow conditions.
Implementation Method 1
The torque being transmitted to the driven pulley 24 provides the necessary clamping force on the drive belt 34 through its torque sensitive mechanical device in order to efficiently transfer torque to the other powertrain components
Implementation Method 2
The effective diameters of the driving pulley 22 and the driven pulley 24 are the result of the equilibrium of forces on the drive belt 34 from a centrifugal actuation system of the driving pulley 22
Implementation Method 3
the angular momentums of all of these components add up during operation... the total angular momentum of the rotating parts of the powertrain needs to be overcome
Data Source
AI summary
A snowmobile has a frame having a tunnel, a motor mounted to the frame, the motor having a motor shaft, at least one ski operatively connected to the frame and a continuously variable transmission. The continuously variable transmission has a driving pulley operatively connected to the motor shaft, a driven pulley, and a drive belt looped around the driving pulley and the driven pulley. The snowmobile also has a drive track operatively connected to the driven pulley, a flexible mechanical element operatively connecting the drive track to the driven pulley, the drive track rotating in a first direction during operation of the snowmobile, and at least one of the motor shaft. The driving pulley and the driven pulley rotate in a second direction opposite the first direction during operation of the snowmobile.