CVT Shift Mechanism Size Reduction via Cam Nesting
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Solution Overview
Problem
Existing V-belt continuously variable transmissions have a large number of components, leading to increased size and complexity, which hinders the achievement of a compact design.
Innovation Solution
The design incorporates a cam member with a concave face and bulge face on the outer surface, a weight retaining plate, and a second shift mechanism with a drive arm and rolling bearing, allowing for reduced size by optimizing the placement of components within the transmission case, including the use of a recessed transmission case part to accommodate the cam member and oil seal member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large number of components are used to form the shift mechanism, then the functionality and reliability are improved, but the size of the mechanism increases
Solution Approach 1:
The patent combines multiple components into integrated assemblies. The cam member integrates the cam face, outer surface, concave face, and bulge face into a single component that performs multiple functions. The weight retaining plate combines the weight retention function with the actuator linkage function, reducing the total number of separate parts while maintaining shift mechanism reliability
Solution Approach 2:
The patent employs nested arrangements where components are positioned within each other's spaces. The oil seal member is fitted into the transmission case and surrounds the drive shaft. The concave face of the cam member is positioned to face the oil seal member, creating a nested configuration that reduces overall mechanism size while maintaining functional integrity
2Length of moving object
If components are arranged to reduce size in the axial direction, then the axial length is reduced, but the width-wise space requirement increases
Solution Approach 1:
The patent redistributes component placement across different spatial dimensions. The cam member features a concave face that faces the oil seal member in the radial direction, while the bulge face extends in the axial direction. This multi-dimensional arrangement allows compact axial length while utilizing radial space efficiently, balancing size reduction in one dimension with space utilization in another
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 enables a significant reduction in size both axially and width-wise, enhancing the compactness of the electronically controlled V-belt continuously variable transmission.
Implementation Method 1
When the drive shaft rotates, the centrifugal weight is moved in the centrifugal direction along the cam face by virtue of centrifugal force, and the movable sheave is moved in the axial direction
Implementation Method 2
A rolling bearing that is non-movable in the axial direction is fitted to a boss of the movable sheave. A drive arm is joined to an outer race of the rolling bearing
Data Source
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AI summary
An electronically controlled V-belt continuously variable transmission is provided with a shift mechanism (75a) that includes a cam member (87) having a cam face (87a) and an outer surface (87b) on a reverse side of the cam face (87a), the cam face (87a) being closer to a fixed sheave (73) in being away from an axis (Xis) of a drive shaft (32) in a centrifugal direction, and that drives a centrifugal weight (93) by the centrifugal force accompanying rotation of the drive shaft (32) to thus move a movable sheave (74) in the axial direction, a concave face (94) that is formed on the outer surface (87b) of the cam member (87) and is recessed toward the outside in the vehicle width direction, and a fitting part (98) that is formed on a transmission case (62, 64) and supports an oil seal member (97) while projecting toward the concave face (94) positioned outside in the vehicle width direction, the oil seal member (97) being fitted into the transmission case (62, 64) and surrounds the drive shaft (32) around the axis (Xis) of the drive shaft (32). This enables the electronically controlled V-belt continuously variable transmission to be reduced in size as much as possible.