Clutch Cam Ring Adjuster With Back-Drive Resistant Wear Compensation
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Solution Overview
Problem
Existing dry friction clutch adjustment mechanisms face issues with back drive of cam surfaces, wear resistance, assembly complexity, cost-effectiveness, and reliability, particularly in compensating for friction disc wear while preventing back drive and ensuring smooth engagement with the engine flywheel and transmission.
Innovation Solution
The friction clutch employs a dual cam ring system with a torsion spring and a baffle with angled cam teeth to prevent back drive, where the second cam ring rotates relative to the first, adjusting for wear by increasing the distance between the diaphragm spring and pressure plate, and a back drive prevention assembly with angled cam teeth reduces load and displacement, enhancing wear resistance and assembly simplicity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a multiple cam ring adjuster is used to compensate for friction disc wear, then the diaphragm spring finger height can be maintained, but back drive of the cam surfaces occurs which varies the position of the diaphragm spring fingers
Solution Approach 1:
The cam surfaces are designed with a specific geometry where the cam surface normal passes through the cam ring rotation center. This preliminary design feature prevents back drive by ensuring that the contact force between cam surfaces always passes through the rotation center, eliminating the moment that would cause reverse rotation. This resolves the contradiction by built-in prevention rather than adding separate prevention mechanisms.
Solution Approach 2:
The invention changes the geometric parameters of the cam surfaces by positioning the cam surface normal to pass through the rotation center. This parameter adjustment ensures that the contact force vector aligns with the rotation center, preventing back drive while maintaining the wear compensation function. The specific angular positioning of the cam surfaces is the key parameter change that resolves the contradiction.
2Device complexity
If conventional cam surfaces are used in the adjustment mechanism, then the structure is simple, but wear resistance is poor due to contact stress
Solution Approach 1:
The cam surfaces are designed with optimized geometric parameters where the contact force passes through the rotation center. This parameter optimization distributes the contact stress more evenly and reduces peak stresses, improving wear resistance without adding complexity. The specific angular orientation and curvature of the cam surfaces are tuned to minimize contact stress while maintaining the wear compensation function.
Solution Approach 2:
The cam surface geometry is preliminarily designed to pass through the rotation center, which inherently reduces contact stress by eliminating lateral forces. This preliminary design feature ensures that the contact force is always directed through the rotation center, reducing friction and wear on the cam surfaces while maintaining structural simplicity.
3Manufacturing precision
If the second cam ring rotates to adjust for friction plate wear, then the distance between the apply spring and pressure plate increases, but variable forces cause back driving of the cam surfaces
Solution Approach 1:
The cam surfaces are preliminarily designed with normals passing through the rotation center, which prevents back drive by ensuring contact forces always pass through the rotation center. This preliminary geometric configuration maintains stable cam ring positions during wear compensation, resolving the contradiction between adjustment capability and positional stability.
Solution Approach 2:
The geometric parameters of the cam surfaces are changed by positioning the contact normal through the rotation center. This parameter change ensures that variable forces during operation do not cause back driving, while still allowing the cam ring to rotate for wear compensation. The specific angular positioning is the key parameter that maintains stability during adjustment.
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 back drive and wear, maintaining consistent engagement performance across varying friction disc thickness, with reduced load and displacement, leading to improved reliability and cost-effectiveness by minimizing contact stress and wear on components.
Implementation Method 1
a torsion spring applying a biasing force to the second cam ring promoting rotation of the second cam ring relative to the first cam ring
Implementation Method 2
Positioned between pressure plate and flywheel is a friction disc... The friction disc is connected with an input shaft of a transmission... friction lining of the friction disc wears
Data Source
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AI summary
A friction clutch for a motor vehicle includes an adjustment mechanism compensating for wear of a friction disk. The adjustment mechanism (40) includes a first cam ring (52) rotatably fixed and a second cam ring (54) rotatable relative to the first cam ring (52). Both cam rings (52,54) have a plurality of cam surfaces configured such that rotation of the second cam ring (54) relative to the first cam ring (52) varies a height of the adjustment mechanism (40). A torsion spring (60) applies a biasing force to the second cam ring (54). A back drive prevention assembly (70) includes a back drive spring (80) attached to the pressure plate and first cam ring (52) to prevent back drive of the second cam ring (54) through a baffle (62) including a plurality of cam teeth (72) formed on a bottom surface of the baffle (62). The cam teeth (72) are formed at an angle A relative to a bottom surface of the baffle (62) decreasing displacement and loads of the back drive spring (80).