CVT Sheave Position Sensing With an External Rotation Sensor
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Solution Overview
Problem
Existing continuously variable transmissions face issues with harness connectivity and sensor exposure to engine heat when the position detecting sensor for the movable sheave is disposed inside the engine unit.
Innovation Solution
The position detecting mechanism is configured with a rotation sensor outside the case, using a shaft that penetrates the case and is rotated in conjunction with the movable sheave, enhancing harness connectivity and reducing sensor exposure to heat.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the position detecting sensor is disposed inside the engine unit, then the detection function is integrated, but the harness connectivity is deteriorated
Solution Approach 1:
The patent divides the position detection system into two parts: a shaft that remains inside the engine unit to maintain integration, and a rotation sensor that is disposed outside the engine unit. This segmentation allows the harness to be routed externally, improving connectivity and reliability while preserving the integrated detection function.
2Device complexity
If the position detecting sensor is disposed inside the engine unit, then the detection function is integrated, but the sensor is exposed to engine heat
Solution Approach 1:
The patent separates the heat-sensitive rotation sensor from the heat-generating engine interior by placing it outside the engine unit, while keeping the shaft inside to maintain the integrated detection function. This resolves the contradiction between integration and heat exposure.
Solution Approach 2:
The shaft acts as an intermediary element that transmits rotational information from the movable sheave inside the engine to the rotation sensor outside the engine. This allows the sensor to be positioned in a thermally favorable location while still detecting internal components.
3Reliability
If the shaft is disposed at a longer distance from the movable sheave, then the sensor can be positioned externally, but the detection accuracy may be reduced
Solution Approach 1:
The shaft serves as an effective intermediary that directly couples the movable sheave's axial movement to rotational motion. By using the sheave's own boss portion as part of the shaft structure, the patent minimizes the distance and potential sources of error, maintaining high detection accuracy while enabling external sensor positioning.
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 improves harness connectivity and reduces sensor exposure to heat, while maintaining accuracy and simplicity in the position detecting mechanism.
Implementation Method 1
The shaft may include a cam converting a linear motion of the movable sheave in the axial direction into a rotational motion of the shaft.
Data Source
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AI summary
There is disclosed an engine unit (8) with a crankshaft (22), a case (2), and a continuously variable transmission (15); the case (2) including a crankcase (21) supporting the crankshaft (22); the continuously variable transmission (15) being of an electronically controlled type and is accommodated in the case (2); the continuously variable transmission (15) including a movable sheave (57) movable in the axial direction of the crankshaft (22) and a position detecting mechanism (100) detecting the position of the movable sheave (57); the position detecting mechanism (100) including a shaft (104), which is disposed to penetrate the case (2) and is rotated in conjunction with the movement of the movable sheave (57), and a rotation sensor (102) that is disposed outside the case (2) and detects the rotational angle of the shaft (104); the position detecting mechanism (100) detecting the position of the movable sheave (57) based on the rotational angle of the shaft (104) detected by the rotation sensor (102).