Lock-up Clutch Protruded Friction Surface Judder Control
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Solution Overview
Problem
The lock-up clutch mechanism in torque converters experiences self-excited vibration known as judder, primarily due to unbalanced surface pressure distribution in the circumferential direction at the friction surface during slipping, which is not adequately addressed by existing techniques.
Innovation Solution
A lock-up clutch mechanism with a friction material having a friction surface featuring a protruded area in the axial direction, formed through a molding process, ensures uniform surface pressure distribution by maintaining high contact pressure at the apex of the protruded area, even with varying piston urging forces, thereby reducing judder.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a lock-up clutch mechanism is operated to connect drive wheel directly in order to reduce energy loss and enhance fuel consumption rate, then fuel efficiency is improved, but self-excited vibration called judder occurs which worsens vehicle comfort
Solution Approach 1:
The friction material is designed with a protruded area at the radial inner side, creating local variation in axial thickness. This local quality change ensures that the radial inner side maintains higher contact pressure with the front cover during slipping, balancing the circumferential pressure distribution and suppressing judder while maintaining lock-up clutch operation
Solution Approach 2:
The axial thickness of the friction material is varied by providing a protruded area, changing the geometric parameter of the friction material. This parameter change allows the friction material to compensate for piston urging force variations and maintain uniform pressure distribution across the friction surface in the circumferential direction
2Stability of the object's composition
If friction material is compressed to reduce density difference between radial inner side and outer side, then pressure distribution is improved, but device complexity increases
Solution Approach 1:
The friction material features a protruded area with a curved surface at the radial inner side, creating a non-uniform axial thickness profile. This curved geometry naturally guides the pressure distribution during clutch operation, maintaining contact pressure balance without requiring complex compression mechanisms or additional components
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 stabilizes friction surface pressure uniformity in the circumferential direction, reducing judder and enhancing vehicle comfort by ensuring consistent contact across the friction surface, regardless of piston force changes.
Implementation Method 1
since contact surface pressure at an apex of the protruded area is high and the friction material can be contacted with the front cover substantially uniformly in a circumferential direction due to flexibility of the friction material
Data Source
AI summary
The present invention provides a lock-up clutch mechanism for a torque converter, comprising a lock-up clutch to which a friction material having a friction surface is secured and a front cover having an engagement surface with which the friction surface is engaged when the friction surface is urged in an axial direction and in which the friction surface of the friction material has a configuration including a protruded area protruding in the axial direction.