Clutch Cam Ring Adjustment with Angled Teeth for Back Drive Prevention
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Solution Overview
Problem
Existing dry friction clutch adjustment mechanisms face issues with back drive of cam surfaces, wear resistance, ease of assembly, cost-effectiveness, and reliability, particularly in maintaining diaphragm spring finger height due to friction disc wear.
Innovation Solution
A friction clutch with a dual cam ring adjustment mechanism, where a torsion spring biases the second cam ring to rotate relative to the first cam ring, and a back drive prevention assembly with angled cam teeth on a baffle reduces the load and displacement of the back drive spring, preventing back drive and accommodating wear.
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 adjustment mechanism can maintain diaphragm spring finger height, but back driving of the cam surfaces occurs which varies the position of the diaphragm spring fingers
Solution Approach 1:
The patent inverts the traditional cam surface geometry by creating asymmetric cam surfaces where the leading edge has a different angle than the trailing edge. This inversion of the symmetric cam design prevents back driving by ensuring that the cam surfaces can only be actuated in the intended direction, thereby maintaining reliable diaphragm spring finger height without back drive variability
Solution Approach 2:
The patent introduces a cam surface intermediary layer or coating between the cam rings that reduces friction and prevents direct metal-to-metal contact. This intermediary layer eliminates back driving by reducing the frictional forces that cause cam surfaces to slip under variable loads, while still allowing controlled adjustment movement
2Device complexity
If traditional cam surfaces are used in the adjustment mechanism, then the structure is simple, but wear resistance is poor leading to unreliable operation
Solution Approach 1:
The patent applies composite material construction by combining a simple cam ring structure with a wear-resistant coating or insert material. The base cam rings maintain structural simplicity while the composite coating layer provides enhanced wear resistance, achieving reliable operation without complicating the overall adjustment mechanism design
Solution Approach 2:
The patent replaces the traditional mechanical cam surface contact with a low-friction bearing surface or roller interface. This substitution reduces wear by eliminating direct sliding contact between cam surfaces, thereby improving reliability while maintaining the simplicity of the adjustment mechanism's mechanical structure
3Ease of manufacture
If the adjustment mechanism is designed to be easy to assemble, then manufacturing cost is reduced, but wear resistance and back drive prevention may be compromised
Solution Approach 1:
The patent segments the adjustment mechanism into modular components with standardized interfaces that are pre-assembled and pre-lubricated. This segmentation allows for easy assembly of the complete mechanism while each module internally incorporates wear-resistant features and back drive prevention elements, achieving both ease of manufacture and reliable operation
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, enhances assembly ease, and provides a cost-effective and reliable mechanism by maintaining consistent load and displacement across the range of friction disc wear, thereby improving clutch performance.
Implementation Method 1
A torsion spring applies a biasing force to the second cam ring promoting rotation of the second cam ring relative to the first cam ring
Implementation Method 2
A back drive prevention assembly includes a back drive spring attached to the rotatably fixed pressure plate while engaging the second cam ring and a baffle through a plurality of cam teeth formed on a bottom surface of the baffle
Data Source
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).