Snowmobile Rear Suspension with Offset Drive Axle and CVT
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Solution Overview
Problem
Snowmobiles face difficulties navigating dense obstacles due to their width, and modified motorcycles for snow travel often exhibit poor performance due to suboptimal weight distribution and unsuitable powertrain components for winter use.
Innovation Solution
A snowmobile design featuring a frame, a single laterally centered ski, a rear suspension assembly with an endless track, and a continuously variable transmission (CVT) that connects the motor to the endless track, optimizing weight distribution and maneuverability by positioning the engine and transmission to minimize lateral extent and improve traction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a snowmobile uses two laterally-spaced skis, then it provides stability on snow, but it increases the width of the snowmobile making it difficult to navigate through dense obstacles
Solution Approach 1:
The snowmobile is divided into separate functional modules: a narrow chassis for maneuverability, and a rear suspension assembly that can be independently positioned. This segmentation allows the main body to remain narrow while the track assembly provides the necessary width for stability when engaged.
Solution Approach 2:
The invention transitions from a lateral width-based stability approach (two spaced skis) to a longitudinal dimension approach (rear-mounted tracked suspension assembly). The drive axle rotation axis is positioned forward of the motor shaft rotation axis, creating a longitudinal offset that improves weight distribution without increasing lateral width.
2Length of moving object
If a motorcycle is adapted for snow travel by replacing wheels with a ski and tracked suspension, then it becomes narrower, but the weight distribution and powertrain configuration are not optimal for snow performance
Solution Approach 1:
The rear suspension assembly is designed to be dynamically adjustable and operatively connectable to the frame. The tracked suspension can be engaged or disengaged based on terrain conditions, allowing the vehicle to adapt its configuration for optimal snow performance rather than being fixed in a suboptimal motorcycle-derived arrangement.
Solution Approach 2:
The invention changes key parameters of the powertrain configuration: the drive axle rotation axis is positioned forward of the motor shaft rotation axis, and the seat is positioned above the motor. These parameter changes optimize weight distribution for snow travel, transferring more weight to the tracked suspension for improved traction.
3Reliability
If the drive axle rotation axis is positioned forward of the motor shaft rotation axis, then weight distribution on the track is improved, but the mechanical linkage becomes more complex
Solution Approach 1:
A continuously variable transmission (CVT) is introduced as an intermediary mechanism between the motor and the drive axle. The CVT includes a primary pulley connected to the motor shaft and a secondary pulley connected to the drive axle, allowing for smooth power transmission and flexible mechanical advantage adjustment without requiring complex rigid linkages.
Solution Approach 2:
The CVT system serves multiple functions: it transmits power from the motor to the drive axle, accommodates the offset between the motor shaft axis and drive axle axis, and provides variable mechanical advantage to optimize weight distribution. This multi-functional approach simplifies the overall mechanical design compared to using separate specialized components for each function.
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
The design enhances maneuverability and performance in deep snow by distributing weight more effectively onto the endless track, allowing for improved navigation through dense obstacles and enhanced traction.
Implementation Method 1
a continuously variable transmission (CVT) operatively connecting the motor to the endless track for driving the endless track
Implementation Method 2
The drive sprocket of the rear suspension assembly is rotatable about the drive axle rotation axis to drive the endless track
Implementation Method 3
The motor includes a shaft rotatable about a shaft rotation axis
Implementation Method 4
distributing weight more effectively onto the endless track, allowing for improved navigation through dense obstacles and enhanced traction
Data Source
AI summary
A snowmobile has a frame, a ski connected to the frame, a seat connected to the frame for accommodating a driver of the snowmobile, a rear suspension assembly operatively connected to the frame, an endless track supported by the rear suspension assembly, a motor supported by the frame, and a continuously variable transmission (CVT) operatively connecting the motor to the endless track. The rear suspension assembly has a suspension assembly drive axle defining a drive axle rotation axis, and a drive sprocket mounted to the drive axle. The motor has a shaft rotatable about a shaft rotation axis. The drive axle rotation axis is positioned forwardly of the shaft rotation axis. The seat is positioned above the motor.