Straddled Vehicle Engine Vibration Isolation via Segmented Rubber Mounts
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Solution Overview
Problem
Existing straddled vehicles face challenges in reducing engine vibration transmission to the rider while maintaining drivability, as increasing vibration isolating rubber thickness leads to tooth jumping and drivability issues due to changes in relative positions between the engine, swing arm, and body frame.
Innovation Solution
A straddled vehicle design featuring vibration absorbing support members with a rubber member between outer and inner cylinders, a rigidly connected swing arm, and restricting members to limit engine movement in specific directions, allowing vibration absorption while maintaining constant sprocket distances and ensuring drivability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the thickness of the cylindrical vibration isolating rubber is increased to reduce engine vibration transmission, then vibration absorption is improved, but the distance between driving sprocket and driven sprocket changes significantly causing tooth jumping
Solution Approach 1:
The vibration isolating rubber is segmented into multiple independent rubber parts (first, second, third, and fourth rubber parts) positioned at different locations around the engine. This segmentation allows each rubber part to independently absorb vibration while maintaining overall dimensional stability, preventing the significant distance changes that cause tooth jumping in the driving system.
Solution Approach 2:
Different rubber parts are positioned at specific locations (front, rear, left, right sides of the engine) to provide localized vibration absorption. The rubber parts have different thicknesses optimized for their specific positions, with front and rear rubber parts having different thicknesses from left and right rubber parts, allowing effective vibration isolation while maintaining precise engine positioning.
2Reliability
If the engine is rigidly connected to the swing arm to maintain constant sprocket distance, then tooth jumping is prevented, but the change of relative positions of drive wheel, swing arm and engine with respect to body frame increases degrading drivability
Solution Approach 1:
The vibration isolating rubber acts as an intermediary element between the engine and the swing arm/body frame. This rubber intermediary allows the engine to be firmly positioned (preventing tooth jumping) while still permitting controlled relative movements of the swing arm and drive wheel with respect to the body frame, thereby maintaining drivability.
3Volume of stationary object
If a single rear shock absorber is used to support the swing arm, then side case capacity is maximized, but the change of relative positions of drive wheel, swing arm and engine with respect to body frame is difficult to restrict
Solution Approach 1:
The vibration isolation function is segmented into multiple rubber parts positioned at different locations around the engine. This segmentation distributes the position-restricting function across multiple points, achieving stable relative positions with a single shock absorber rather than requiring multiple shock absorbers that would reduce side case capacity.
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 solution effectively reduces engine vibration transmission to the rider, maintains drivability by restricting engine movement, and allows for increased side case capacity without the need for additional shock absorbers, enhancing overall vehicle stability and performance.
Implementation Method 1
a plurality of vibration absorbing support members that support the engine at the body frame
Implementation Method 2
each of the plurality of vibration absorbing support members includes an outer cylinder, an inner cylinder arranged in the outer cylinder and a rubber member provided between the outer cylinder and the inner cylinder
Data Source
AI summary
A swing arm extends rearwardly from an engine, and a pair of side cases is arranged leftwardly and rightwardly of the swing arm. The swing arm is supported at a body frame by a single rear shock absorber. The engine is supported at the body frame by a plurality of vibration absorbing support members. Each vibration absorbing support member has a structure in which a rubber member is arranged between an outer cylinder and an inner cylinder. The engine is attached to the inner cylinder with use of an engine support shaft, and the body frame is attached to the outer cylinder with use of an engine bracket. The rubber member has projections being in contact with an inner surface of the outer cylinder and recesses not being in contact with the inner surface of the outer cylinder. The swing arm is rigidly and pivotally connected to the engine.