Clutch Pressure Plate Stroke Limiting via Angular Rotation

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Solution Overview

Problem

Existing clutches with axial stops for limiting the axial stroke of the pressure plate relative to the driven member are limited in their ability to effectively manage excessive engine braking effects, leading to potential coupling loss and operational inefficiencies.

Innovation Solution

A clutch design incorporating an angular stroke limiter, comprising slots and columns, limits the relative rotation between the driven member and pressure plate, preventing excessive axial movement without the need for axial stops, allowing controlled slipping to reduce engine braking effects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If axial stops are used to limit the axial stroke of the pressure plate, then the axial movement is constrained, but coupling loss occurs and operational efficiency decreases

Engineering Contradiction:
Improveaxial stroke of pressure plateVSAvoidcoupling functionality
Core Design Contradiction:
Length of moving objectVSReliability

Solution Approach 1:

The patent transitions from limiting axial movement (one dimension) to limiting rotational movement (another dimension). The angular stroke limiter restricts the relative rotation between driven member and pressure plate, which indirectly controls the axial stroke without requiring axial stops. This dimensional change eliminates coupling loss while maintaining operational efficiency.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

Instead of directly limiting the axial stroke of the pressure plate through axial stops, the invention inverts the approach by limiting the rotational stroke angularly. The angular stroke limiter prevents excessive rotation, which in turn prevents excessive axial movement, achieving the same goal through an opposite mechanism.

Inventive Principle:
Principle #13The other way round (Inversion)

2Length of moving object

If axial stops are used to limit pressure plate movement, then movement is constrained, but device complexity increases

Engineering Contradiction:
Improveaxial stroke of pressure plateVSAvoidclutch structure
Core Design Contradiction:
Length of moving objectVSDevice complexity

Solution Approach 1:

The patent replaces axial stopping mechanisms with an angular stroke limiting mechanism. By controlling rotation in the angular dimension rather than directly controlling linear movement in the axial dimension, the structure is simplified while achieving the same functional outcome of limiting pressure plate movement.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The angular stroke limiter serves multiple functions: it limits the axial stroke of the pressure plate, prevents coupling loss, and maintains operational efficiency. This single component achieves what previously required separate axial stops and other mechanisms, reducing overall device complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Length of moving object

If the pressure plate axial stroke is limited by axial stops, then the axial load increases due to impact, but this adds to the elastic member load and reduces reliability

Engineering Contradiction:
Improveaxial stroke of pressure plateVSAvoidaxial load capacity
Core Design Contradiction:
Length of moving objectVSStrength

Solution Approach 1:

The patent eliminates impact loads in the axial dimension by controlling movement through the rotational dimension. The angular stroke limiter prevents the pressure plate from striking axial stops, thereby eliminating impact loads and reducing the total axial load on elastic members, which improves reliability.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The angular stroke limiter acts as a preventive mechanism that stops excessive rotation before it can cause excessive axial movement and impact. By anticipating and preventing the harmful condition beforehand, the system avoids impact loads and protects the elastic members from excessive stress.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

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 angular stroke limiter ensures controlled slipping and prevents coupling loss, maintaining clutch functionality while reducing engine braking effects, enhancing operational efficiency and reliability.

Implementation Method 1

a first cam profile integral with the driven member, and coacting with a second cam profile integral with the pressure plate. The first cam profile and the second cam profile are configured so that, if a torque is transferred from the driven member toward the drive input member, the driven member rotates relative to the pressure plate about the axis of the clutch and the rotation movement between the driven member and the pressure plate generates, by means of the first cam profile and the second cam profile, an axial thrust on the pressure plate

Methodology Applied
Scientific EffectCam mechanism: Cam

Implementation Method 2

The pressure plate is elastically stressed toward the driven member to compress the first discs and the second discs against one another

Methodology Applied
Scientific EffectElastic stress: Elasticity

Implementation Method 3

a pressure plate mounted on the driven member and axially movable relative thereto parallel to the rotation axis of the clutch, the pressure plate being elastically stressed toward the driven member to compress the first discs and the second discs against one another, so that they transmit the torque from the drive input member to the driven member by friction

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 4

To limit the axial movement of the pressure plate relative to the driven member, an angular stroke limiter is provided, which limits the relative rotation between the driven member and the pressure plate and thereby limits the movement of the pressure plate away from the driven member

Methodology Applied
Scientific EffectMechanical constraint:

Data Source

PatentEP4121664B1clutch
Publication Date: 2025.08.20 PIAGGIO & C SPA
  • EP4121664B1 patent drawingFigure 1
  • EP4121664B1 patent drawingFigure 2
  • EP4121664B1 patent drawingFigure 3

AI summary

The clutch (1) comprises a housing (3) connected to a drive input member(5). First friction discs (7) are mounted in the housing (3) and rotate therewith. Second friction discs (9) are mounted on a driven member (11). A pressure plate (13) is elastically stressed toward the driven member (11) to compress the first and the5second friction discs (7, 9) against one another. Cam profiles (31, 33) integral with the driven member (11) and with the pressure plate (13), generate a thrust to move the driven member and pressure plate away from each other when it is necessary to reduce the pressure exerted by the pressure plate (13) on the first and second friction discs (7, 9). An angular stroke limiter limits the relative rotation between the driven 10member (11) and the pressure plate (13) and thereby limits the movement of thepressure plate (13) away from the driven member (11).