Clutch System Fluidic Actuation Ratio Optimization

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Solution Overview

Problem

Current clutch systems lack an optimal design that balances the transmission ratio of the pressure plate assembly and the actuating device, leading to inefficiencies and increased path losses due to separate development of these components.

Innovation Solution

A clutch system with a fluidic actuating device featuring a slave cylinder and master cylinder, along with a plate spring that increases the transmission ratio of the pressure plate assembly to greater than 5, and a clutch cover made of thin sheet metal, optimized for reduced material usage and increased stiffness, which reduces path losses and pedal force requirements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the transmission ratio of the pressure plate assembly is increased to greater than 5, then the path losses are reduced and the clutch system efficiency is improved, but the release force required from the actuating device increases

Engineering Contradiction:
Improvepath lossesVSAvoidrelease force
Core Design Contradiction:
Loss of energyVSForce

Solution Approach 1:

The patent employs a hydraulic actuating device with a master cylinder and slave cylinder to generate and transmit force fluidically. The hydraulic system amplifies the release force through the ratio of piston surface areas, compensating for the increased force requirement resulting from the high transmission ratio of the pressure plate assembly. This allows the clutch system to maintain high efficiency with minimal path losses while requiring only moderate actuating force from the driver.

Inventive Principle:
Principle #29Pneumatics and hydraulics

2Loss of substance

If the clutch cover is made of thin sheet metal to reduce material usage and installation space, then the manufacturing cost is reduced and installation space is minimized, but the stiffness and strength of the clutch cover decrease

Engineering Contradiction:
Improvematerial usageVSAvoidclutch cover stiffness
Core Design Contradiction:
Loss of substanceVSStrength

Solution Approach 1:

The patent utilizes a thin-walled sheet metal clutch cover that achieves sufficient structural strength and stiffness through optimized geometric design and appropriate material selection, rather than relying on increased material thickness. This approach minimizes material usage and installation space while maintaining the necessary mechanical properties to withstand operating loads.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The patent changes material parameters by selecting appropriate sheet metal materials with optimized mechanical properties and adjusting geometric parameters such as wall thickness, rib configurations, and support structures to achieve the required stiffness and strength. This allows the clutch cover to be made thinner and lighter while still meeting performance requirements.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If the clutch device and actuating device are optimized independently with separate development, then each component can be optimized for its specific function, but the overall system efficiency is compromised due to mismatched transmission ratios

Engineering Contradiction:
Improvecomponent optimizationVSAvoidsystem efficiency
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The patent merges the optimization of the clutch device and actuating device into a unified system design process. The transmission ratio of the pressure plate assembly is specifically optimized in conjunction with the actuating device parameters to achieve minimal path losses and maximum overall system efficiency. This integrated approach ensures that the release force requirements of the high-ratio pressure plate assembly are properly matched with the capabilities of the hydraulic actuating device, eliminating the inefficiencies that arise from independent optimization.

Inventive Principle:
Principle #5Merging (Combining)

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 efficiency of the clutch system by minimizing path losses and reducing the driver's effort to disengage the clutch, while allowing for cost-effective manufacturing and reduced installation space.

Implementation Method 1

a fluidic actuating device (3) for engaging and/or disengaging the clutch device (2), with the fluidic actuating device (3) having at least one slave cylinder (20) with a slave piston (21) and at least one master cylinder (24) with a master piston (25), which is fluidly connected to the slave cylinder (20)

Methodology Applied
Scientific EffectHydraulic pressure transmission: Hydraulic Press

Implementation Method 2

at least one plate spring (8), which can be actuated by the actuating device (3), and at least one pressure plate (5), which can be displaced to a limited extent in the axial direction (A) of the clutch device (2) by the plate spring (8), for frictionally locking a clutch disc (6)

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Implementation Method 3

for frictionally locking a clutch disc (6) between the pressure plate (5) and the counter-pressure plate (4)

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3247918B1Clutch system
Publication Date: 2019.09.18 SCHAEFFLER TECHNOLOGIES AG & CO KG
  • EP3247918B1 patent drawingFigure 1
  • EP3247918B1 patent drawingFigure 2
  • EP3247918B1 patent drawing

AI summary

The invention relates to a clutch system (1) comprising a clutch device (2) and a fluidic actuation device (3) for engaging and/or disengaging the clutch device (2), said clutch device (2) having at least one counter-pressure plate (4), at least one clutch cover (7) with at least one diaphragm spring (8) pivotally mounted on a pivoting radius (17), and at least one pressure plate (5) for frictionally clamping a clutch disk (6) between the pressure plate (5) and the counter-pressure plate (4), said pressure plate being movably mounted, limited in an axial direction (A) of the clutch device (2) by the diaphragm spring (8). The diaphragm spring (8) acts upon the contact plate (5) in an active radius (19) which is outside the pivoting radius (17) in the radial direction (R) of the clutch device (2) and can be actuated by the actuation device (3) in an actuation radius (18) which is inside the pivoting radius (17) in the radial direction (R), with iDP = (pivoting radius - actuation radius) / (active radius - pivoting radius) >= 5. The fluidic actuation device (3) has at least one slave cylinder (20) having a slave piston (21), which slave cylinder acts directly or indirectly upon the diaphragm spring (8), and at least one master cylinder (24) having a master piston (25), which master cylinder is fluidically connected to the slave cylinder (20), the following applying for the piston areas: iH = (area slave piston) / (area master piston), with 1.5 <= iH <= 3.5.