Axle Drive Module Test Bench Layout for Close Shaft Coupling

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Solution Overview

Problem

Existing vehicle test benches face challenges in testing electric axle drive modules due to closely spaced shafts and high rotational speeds, requiring expensive special gearboxes or integrated electric motors, which are not suitable for precise torque measurement and are costly, especially for passenger cars.

Innovation Solution

A drive unit for a test bench comprising an electric drive motor radially enclosed by a frame, with vibration-damping properties, allowing coupling to an axle drive module's input shaft through an intermediate shaft or compensating element, and featuring a torque measuring flange for precise torque measurement, without needing a gearbox.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a special gearbox with radial offset is used to couple the input shaft and output shaft, then the shafts can be connected to the test bench, but the device complexity and cost increase significantly

Engineering Contradiction:
Improvecoupling capabilityVSAvoidgearbox structure
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent introduces an intermediate shaft as a mediator between the input shaft and output shaft. This intermediate shaft enables the coupling of closely spaced shafts without requiring a complex special gearbox with radial offset, thereby reducing device complexity while maintaining the coupling capability needed for test bench operation.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Volume of moving object

If the radial distance between input shaft and output shaft is small, then the axle drive module is compact, but it becomes difficult to couple the shafts to the test bench

Engineering Contradiction:
Improveaxle drive module sizeVSAvoidshaft coupling
Core Design Contradiction:
Volume of moving objectVSEase of operation

Solution Approach 1:

The patent resolves the spatial constraint by changing the arrangement from a radial configuration to an axial configuration. The intermediate shaft is arranged axially between the input and output shafts, allowing coupling in the axial dimension rather than requiring radial offset, thus maintaining compactness while enabling test bench coupling.

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

3Speed

If high input speeds are required, then the axle drive module performance is improved, but the vibration damping properties and rigidity of the test bench must be correspondingly high

Engineering Contradiction:
Improveinput shaft speedVSAvoidtest bench rigidity
Core Design Contradiction:
SpeedVSStrength

Solution Approach 1:

The intermediate shaft acts as a vibration-damping intermediary in the power transmission path. By introducing this additional shaft between the input and output shafts, the system can achieve high input speeds while the intermediate shaft helps to dampen vibrations, reducing the rigidity requirements for the test bench structure.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP4726350A1Drive unit for a test bench for testing an electric axle drive module for a motor vehicle, and test bench
Publication Date: 2026.04.15 ZF FRIEDRICHSHAFEN AG
  • EP4726350A1 patent drawingFigure 1~5
  • EP4726350A1 patent drawingFigure 6~8
  • EP4726350A1 patent drawing

AI summary

The invention relates to a drive unit (100) for a test bench (220) for testing an electric axle drive module (240) for a motor vehicle, comprising an electric drive motor (110) and a frame (130), wherein the drive motor (110) is radially enclosed by the frame (130) and is held in the frame (130) such that it can drive an input shaft (241) of an axle drive module (240). The drive unit (100) according to the invention is characterized in that the frame (130) has at least one opening (140) which is configured to guide an output shaft (242, 243) of the axle drive module (240) through the frame (130) parallel to the drive motor (110). The invention further relates to a corresponding test bench.