Leaf-Spring Friction Clutch for Self-Reinforcing Torque Transfer

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Solution Overview

Problem

Existing friction clutches require high actuation forces to achieve large contact forces necessary for transmitting high engine torques, which can be impractical and inefficient, especially in applications like motorcycles where torque transfer needs to be balanced between tension and thrust.

Innovation Solution

A friction clutch design utilizing leaf springs that are connected to a pressure plate and a clutch cover, allowing for self-reinforcement by amplifying contact force through a transmission ratio, with leaf springs arranged in pressure plate cams and connected to tongues of a plate spring, enabling engagement in the pulling direction and disengagement in the thrust direction, thereby reducing the maximum transferable thrust torque.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If high clamping forces are used to transmit high engine torques, then torque transmission reliability is improved, but actuation force requirements increase

Engineering Contradiction:
Improvetorque transmission reliabilityVSAvoidactuation force
Core Design Contradiction:
ReliabilityVSForce

Solution Approach 1:

The friction clutch utilizes self-reinforcement where the clutch cover and pressure plate work together to amplify the actuation force. During engagement, the clutch cover moves relative to the pressure plate, and the leaf springs convert this relative motion into amplified contact force between the friction surfaces, allowing the system to generate its own reinforcing force without requiring proportionally high actuation forces

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The leaf springs provide dynamic force amplification through their elastic deformation characteristics. As the clutch engages and the clutch cover moves relative to the pressure plate, the leaf springs deflect and generate increasing contact force, creating a dynamic self-reinforcing effect that enhances torque transmission capability while maintaining moderate actuation force requirements

Inventive Principle:
Principle #15Dynamics

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 design enhances the self-reinforcement mechanism to increase contact force while reducing the maximum transferable thrust torque, allowing for efficient torque transmission with lower actuation forces, particularly beneficial in motorcycle applications.

Implementation Method 1

The leaf springs extend between a first end and a second end at least along a circumferential direction and along an axial direction... exert a force on the tongues of the disc spring engaging the friction clutch during acceleration of the internal combustion engine

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

The clamping force of modern dry clutches is typically generated by a disc spring or compression spring... The force exerted by the disc spring or compression spring on the pressure plate correlates with the clutch actuation force

Methodology Applied
Scientific EffectElastic compression: Spring

Implementation Method 3

the pressure plate is provided for frictionally pressing a clutch disc between the counter plate and the pressure plate

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3665397B1Self-reinforcing friction clutch having leaf springs
Publication Date: 2023.11.01 SCHAEFFLER TECHNOLOGIES AG & CO KG
  • EP3665397B1 patent drawingFigure 1~2
  • EP3665397B1 patent drawingFigure 3~4
  • EP3665397B1 patent drawingFigure 5~6

AI summary

The invention relates to a friction clutch (1) having a plate spring (2), which engages with the friction clutch (1), a clutch cover (3), and a displaceable pressing plate (6), which is limited in the axial direction (4) and is attached by leaf springs (5) to the clutch cover (3) for conjoint rotation, wherein the leaf springs (5) are permanently attached to tabs (7) of the plate springs (2) in the axial direction (4).