Steering Column Belt Drive With Releasable Motor Coupling

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Solution Overview

Problem

The existing auxiliary power drives for motor vehicle steering systems are difficult to repair, particularly when replacing the motor, as the drive wheel must be removed and reinstalled, leading to undefined belt tension due to manufacturing and assembly tolerances, making the process laborious and time-consuming.

Innovation Solution

A releasable coupling between the motor shaft and drive wheel allows for spatial separation of the drive connection, enabling the motor to be removed without dismantling the drive wheel, maintaining the center distance and simplifying belt tension readjustment, with adjustable coupling elements and a positioning device for easy motor replacement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the drive wheel is permanently connected to the motor shaft, then the motor can be securely mounted in the housing, but the motor replacement becomes labor-intensive and time-consuming requiring disassembly and reassembly of the drive wheel

Engineering Contradiction:
Improvemotor mounting securityVSAvoidmotor replacement effort
Core Design Contradiction:
ReliabilityVSEase of repair

Solution Approach 1:

The permanent connection between the motor shaft and drive wheel is divided into two separable parts: a mounting portion on the motor shaft and a corresponding reception portion on the drive wheel. This segmentation allows the motor to be detached and replaced independently while the drive wheel remains in place, resolving the contradiction between secure mounting and ease of repair.

Inventive Principle:
Principle #1Segmentation

2Ease of repair

If the drive wheel is removed from the housing for motor replacement, then the motor can be replaced, but the belt tension becomes undefined due to manufacturing and assembly tolerances

Engineering Contradiction:
Improvemotor accessibilityVSAvoidbelt tension consistency
Core Design Contradiction:
Ease of repairVSManufacturing precision

Solution Approach 1:

The drive wheel is extracted from the motor assembly process and kept permanently mounted in the housing. Only the motor is removed and replaced, while the drive wheel remains in its precise position. This eliminates the need to deal with belt tension adjustments during motor replacement, as the drive wheel's position relative to the housing remains constant.

Inventive Principle:
Principle #2Taking out (Extraction)

3Ease of repair

If the center distance is altered during motor replacement, then the motor can be reinstalled, but the belt tension must be readjusted to ensure smooth operation

Engineering Contradiction:
Improvemotor reinstallabilityVSAvoidbelt tension adjustment
Core Design Contradiction:
Ease of repairVSEase of operation

Solution Approach 1:

The drive wheel is pre-positioned and securely mounted in the housing before motor replacement occurs. This preliminary positioning ensures that when the motor is reinstalled, the center distance between the drive wheel and output wheel remains consistent, eliminating the need for belt tension readjustment and ensuring smooth operation from the start.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3898381B1Power assistance drive for a steering column, and steering column for a motor vehicle
Publication Date: 2024.02.07 THYSSENKRUPP PRESTA AG
  • EP3898381B1 patent drawingFigure 1
  • EP3898381B1 patent drawingFigure 2~3
  • EP3898381B1 patent drawingFigure 4~6

AI summary

The invention relates to a power assistance drive (6) for a steering column (1) of a motor vehicle, comprising a belt drive arranged in a housing, having an input pulley (63), which is coupled to the motor shaft (62) of a motor (61) so as to be rotationally drivable about an input axis (A) and which is drivingly connected to an output pulley (64) by means of a driving belt (65), which output pulley is mounted for rotation about an output axis (S) in the housing (31). The aim of the invention is to enable a repair-friendly design and easier replacement of the motor. This aim is achieved, according to the invention, in that the motor (61) is releasbly attached to the housing (31) and the motor shaft (62) is connected to the input pulley (63) by means of a releasble clutch (7).