Tooth Clutch Back-Taper Angle Design for Gear Hopout Prevention
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Solution Overview
Problem
Conventional tooth clutches in vehicle transmissions experience gear hopout due to misalignment caused by external forces, particularly during retarder operation, where the self-retaining action from back-taper design is insufficient, leading to unstable engagement and loss of torque transfer.
Innovation Solution
Increasing the back-taper angle of clutch teeth to ensure that the parallel component of the sleeve clutch force is larger than the sum of friction forces, thereby preventing gear hopout, and using a combination of manufacturing methods to achieve the required back-taper angle without excessive cost, such as using rolling for small angles and shaping for larger angles only where necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the back-taper angle of clutch teeth is increased to prevent gear hopout, then the self-retaining ability is improved, but the manufacturing complexity and cost increase
Solution Approach 1:
The patent applies local quality by differentiating the back-taper angle requirements for different clutch teeth based on their operational conditions. Specifically, clutch teeth subjected to misalignment forces (e.g., during retarder operation) are given larger back-taper angles, while other teeth use conventional angles. This selective application of enhanced geometry prevents gear hopout only where necessary, resolving the contradiction between improved reliability and reduced manufacturing complexity.
2Reliability
If conventional manufacturing methods are used to achieve large back-taper angles, then the self-retaining ability is improved, but the manufacturing cost increases significantly
Solution Approach 1:
The patent employs parameter changes by transitioning from conventional small back-taper angles to specifically enlarged angles for affected clutch teeth. This parameter modification is applied selectively based on operational analysis of which teeth experience misalignment forces. The changed geometric parameter (back-taper angle) directly improves the self-retaining ability and prevents gear hopout while controlling manufacturing costs through targeted application.
3Stability of the object's composition
If the back-taper angle is increased to prevent gear hopout during retarder operation, then the stability of engagement is improved, but the friction forces increase
Solution Approach 1:
The patent applies local quality by enhancing the back-taper angle specifically for clutch teeth that experience misalignment during retarder operation, while leaving other clutch teeth with conventional geometry. This localized enhancement stabilizes engagement only where needed, preventing gear hopout during critical operations without unnecessarily increasing friction forces across all clutch teeth, thus resolving the contradiction between engagement stability and friction force reduction.
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
Enhances the self-retaining ability of tooth clutches, preventing gear hopout even under misaligned conditions, while minimizing the use of costly manufacturing methods by applying large back-taper angles only where needed, such as during retarder and engine braking operations.
Implementation Method 1
the parallel component of the sleeve clutch force must be larger than the sum of the friction forces between the clutch teeth and between the spline teeth
Data Source
AI summary
A system is provided for preventing gear hopout in a tooth clutch in a vehicle transmission, the tooth clutch including an engaging sleeve having sleeve clutch teeth. The tangent function for at least one of driving back-taper angle and braking back-taper angle is larger than the average value of clutch coefficient of friction and spline coefficient of friction multiplied by the sum of unity and the ratio of clutch teeth pitch diameter and spline teeth pitch diameter.