Multi-Plate Clutch Test Bench for Accurate Drag Torque Measurement

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Solution Overview

Problem

Existing test bench concepts for multi-plate clutches face challenges in accurately measuring torque due to variable roller bearing friction, which is influenced by speed, external load, and lubricant resistance, leading to reduced testing accuracy.

Innovation Solution

A test stand arrangement with a clutch unit featuring a first and second disk carrier, a drive section with a motor for relative movement, and a measuring unit to detect friction torque of the bearing device, allowing for precise subtraction of bearing friction from drive torque to determine drag or idling torque accurately, utilizing a fluid bearing for zero-speed friction measurement and improved damping.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If roller bearings are used to support the driven shaft, then the shaft can rotate smoothly, but the bearing friction introduces disturbance variables that reduce measurement precision

Engineering Contradiction:
Improverotation smoothnessVSAvoidtorque measurement accuracy
Core Design Contradiction:
SpeedVSMeasurement precision

Solution Approach 1:

The patent extracts the friction source (roller bearing) from the measurement system by supporting the driven shaft on frictionless magnetic bearings, eliminating the disturbance variable that compromises torque measurement precision while maintaining rotation smoothness

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical roller bearing system with magnetic bearings that provide frictionless support, substituting mechanical contact with magnetic fields to eliminate friction-induced measurement errors while preserving rotational functionality

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Adaptability or versatility

If both inner and outer disk carriers are rotated during testing, then the clutch operation is accurately simulated, but the bearing friction varies with speed and load, reducing testing accuracy

Engineering Contradiction:
Improveclutch operation simulationVSAvoiddrag torque measurement accuracy
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent removes the variable friction disturbance by extracting the roller bearing and replacing it with magnetic bearings, allowing both disk carriers to rotate for accurate clutch simulation while eliminating the speed- and load-dependent friction that compromises drag torque measurement accuracy

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the fundamental parameter of bearing friction from variable (speed- and load-dependent in roller bearings) to constant/zero (in magnetic bearings), enabling accurate drag torque measurements while maintaining the ability to simulate various clutch operating conditions

Inventive Principle:
Principle #35Parameter changes

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 setup enables high-precision measurement of small torques, significantly improving testing accuracy by isolating friction torque from drive torque, and providing enhanced operating behavior through friction-free fluid bearings.

Implementation Method 1

the driven shaft (7, 22) being supported by a fluid bearing (15) to rotate friction-free

Methodology Applied
Scientific EffectFluid bearing: Lubrication

Data Source

PatentEP3625532B1Test bench arrangement for testing a multi-plate clutch
Publication Date: 2021.07.07 ZF FRIEDRICHSHAFEN AG
  • EP3625532B1 patent drawingFigure 1
  • EP3625532B1 patent drawingFigure 2
  • EP3625532B1 patent drawingFigure 3

AI summary

Friction plate stacks for clutches and brakes are used in automatic transmissions, for instance. The friction plates are mounted in a test chamber on what are known as inner and outer plate carriers in clutch test benches for clutches of this kind. According to the invention, a test bench arrangement (1) for testing a multi-plate clutch, having a clutch unit (2), wherein the clutch unit (2) has a first clutch plate carrier (5) and a second clutch plate carrier (6), wherein the first clutch plate carrier (5) is movable relative to the second clutch plate carrier (6), having a drive section (3), wherein the drive section (3) has a driving device (10) to generate the relative movement between the first and the second clutch plate carrier (5), (6), a first driven shaft (7) and at least one first bearing apparatus (11) for mounting the first shaft (7) is proposed. The first clutch plate carrier (5) is drivingly connected to the driving device (10) through the first shaft (7), and the first shaft (7) is mounted for rotation by the first bearing apparatus (11). The test bench arrangement (1) has a measuring unit (12) for determining a first friction torque of the first bearing apparatus (11).