Hybrid Friction Clutch Spring Layout for Stable Torque Modulation

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Solution Overview

Problem

Current friction clutch devices in hybrid modules for motor vehicles face challenges in starting a coupled combustion unit efficiently and controlling clutch torque, particularly when engaged in overrun mode, due to uneven axial force application and potential wear issues.

Innovation Solution

A friction clutch device with a spring device arranged to apply axial forces radially symmetrically, using a ring-shaped or segmented spring design that is fixed to the force transmission device, allowing for controlled modulation of contact pressure and torque transmission, ensuring reliable engagement and disengagement without tipping or wear.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional disc spring is used to generate clamping force, then the clutch can transmit torque, but the axial force is applied unevenly causing misalignment and wear

Engineering Contradiction:
Improveclutch operation reliabilityVSAvoidcomponent wear and misalignment
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The disc spring is segmented into multiple independent spring elements (typically 3-6 segments) arranged radially around the clutch assembly. Each segment independently applies axial force to the friction pack, distributing the load evenly and preventing misalignment. This segmentation resolves the contradiction by maintaining reliable torque transmission while eliminating the harmful uneven force distribution that causes wear and misalignment in conventional single-disc spring designs.

Inventive Principle:
Principle #1Segmentation

2Ease of operation

If the clutch is engaged in overrun mode to start the combustion engine, then the combustion unit can be started, but the clutch torque must be precisely controlled within a specific range

Engineering Contradiction:
Improvecombustion engine starting capabilityVSAvoidtorque control complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The spring elements are designed with specific elastic properties and pre-load characteristics that automatically adjust the clamping force based on the operational state. During overrun mode, the dynamic response of the spring segments provides inherent torque control within the required range, enabling reliable combustion engine starting without requiring complex external control systems. This dynamic design resolves the contradiction by achieving ease of operation while minimizing device complexity.

Inventive Principle:
Principle #15Dynamics

3Ease of manufacture

If the spring device is positioned asymmetrically, then the structure may be simpler, but the axial force vectors are at different radial positions causing tilting and uneven wear

Engineering Contradiction:
Improvespring device positioningVSAvoidtilting and uneven wear
Core Design Contradiction:
Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

While individual spring segments are positioned asymmetrically around the clutch assembly to simplify manufacturing and assembly, their collective arrangement creates a balanced force distribution. The segments are strategically positioned at specific angular intervals (e.g., every 60 degrees for 6 segments) so that their combined axial force vectors converge at the same radial position, preventing tilting and uneven wear. This controlled asymmetry resolves the contradiction by maintaining ease of manufacture while eliminating harmful effects through geometric balancing.

Inventive Principle:
Principle #4Asymmetry

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

Enables efficient and low-wear starting of a coupled combustion unit by modulating contact pressure and controlling clutch torque, reducing the risk of component misalignment and wear, while maintaining torque transmission efficiency.

Implementation Method 1

a spring device (50), arranged axially between the force transmission device (10) and the friction pack (30), with which a spring force can be applied to the friction pack (30) in the axial direction, depending on the axial spring travel of the spring device (50)

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

A friction clutch device for a motor vehicle for the frictional transmission of torque between a coupled internal combustion engine and a coupled transmission

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3788272B1Friction clutch unit, hybrid module, and drive arrangement for a motor vehicle
Publication Date: 2023.01.04 SCHAEFFLER TECHNOLOGIES AG & CO KG
  • EP3788272B1 patent drawingFigure 2~3

AI summary

The invention relates to a friction clutch unit, a hybrid module and a drive arrangement for a motor vehicle. The friction clutch unit comprises a force-transmitting unit (10) and a diaphragm spring (20), wherein the force-transmitting unit (10) is configured to transfer a substantially axially oriented compressive force (21), which is or can be exerted by the diaphragm spring (20), and further comprises a friction pack (30) which has a plurality of fins (31, 32) and by which torque can be transferred frictionally by means of an axially acting force (40) when the fins are pressed together, wherein a spring unit (50) is arranged axially between the friction pack (30) and the force-transmitting unit (10), with which spring unit (50) a spring force (61) can be applied to the friction pack (30) subject to the axial spring path (51) of the spring unit (50) in the axial direction, wherein the spring unit (50) is arranged and configured such that when the spring unit (50) is loaded with the compressive force (21), the vectors of the force pair (60) generated by the spring unit (50) in the axial direction have substantially the same radial position. With the friction clutch unit proposed here, a unit is provided that, with modulation of the pressing force acting on the friction pack, enables a coupled combustion engine to be started by means of a connected electrical machine.