Welded Sensor Gear for Electromechanical Power Steering

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Solution Overview

Problem

Existing electromechanical power steering systems face challenges in attaching sensor elements securely and efficiently, requiring significant installation space and processing effort due to the need for separate fastening devices and complex surface preparation.

Innovation Solution

The gear wheel and sensor element are made of plastic and welded together at their contact surfaces, forming a direct, integral, and durable connection that eliminates the need for separate fastening devices and reduces installation space and manufacturing effort.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the sensor element is attached to the steering shaft using a press fit with plastic fasteners, then the sensor element can be securely attached, but the installation space required is limited and the attachment reliability is insufficient

Engineering Contradiction:
Improveattachment reliabilityVSAvoidinstallation space
Core Design Contradiction:
ReliabilityVSArea of stationary object

Solution Approach 1:

The sensor element is integrated directly into the gear structure, merging two previously separate components (sensor element and gear) into a single unified component. This eliminates the need for separate fastening devices and reduces installation space while maintaining secure attachment through the material bond between the sensor element and gear

Inventive Principle:
Principle #5Merging (Combining)

2Ease of manufacture

If the sensor element is bonded to the steering shaft using UV-curable adhesive, then the sensor element can be attached, but the process is labor-intensive and time-consuming

Engineering Contradiction:
Improvemanufacturing effortVSAvoidbonding time
Core Design Contradiction:
Ease of manufactureVSLoss of time

Solution Approach 1:

The chemical bonding process (UV-curable adhesive) is replaced with a welding process that joins the sensor element and gear through localized melting and fusion. This substitution eliminates the need for adhesive application, curing time, and associated labor-intensive steps, significantly reducing manufacturing time and effort

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

3Reliability

If a plastic part is attached to the steering shaft and the sensor element is then bonded to it, then the sensor element can be secured, but the installation space and manufacturing complexity increase

Engineering Contradiction:
Improveattachment securityVSAvoidmanufacturing complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The sensor element is integrated directly into the gear structure, merging two previously separate components (sensor element and gear) into a single unified component. This eliminates the need for intermediate plastic parts and multiple attachment steps, reducing both installation space requirements and manufacturing complexity while maintaining secure attachment

Inventive Principle:
Principle #5Merging (Combining)

4Ease of manufacture

If the sensor element is thermally shrunk onto the steering shaft, then the sensor element can be attached, but additional machining steps are required

Engineering Contradiction:
Improveattachment processVSAvoidmachining steps
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The sensor element is integrated directly into the gear structure during the gear manufacturing process, merging the attachment step with the existing gear production. This eliminates the need for separate thermal shrinking operations and additional machining steps, simplifying the overall manufacturing process

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 solution enables a reliable, secure, and compact attachment of the sensor element to the gear wheel, reducing manufacturing costs and effort while ensuring a durable connection, allowing for efficient integration into the power steering system.

Implementation Method 1

the gear and the sensor element are each made of plastic, at least in the area of the contact surface, and the gear is welded to the sensor element

Methodology Applied
Scientific EffectWelding: Welding

Data Source

PatentEP3250440B1Apparatus for introducing an auxiliary torque into a steering shaft of an electromechanical power steering system
Publication Date: 2021.04.21 THYSSENKRUPP AG
  • EP3250440B1 patent drawingFigure 1~4
  • EP3250440B1 patent drawingFigure 5~11

AI summary

The present invention relates to an apparatus (2) for introducing an auxiliary torque and/or an additional steering angle into a steering shaft (1) of an electromechanical power steering system (100), comprising a gear (20) which is attached to the steering shaft (1) in a rotationally fixed manner and which is operatively connected to a drive element (22) of a drive motor (24) and can be driven in a rotational manner by said drive element, and a sensor element (51) which is connected to the steering shaft (1) in a rotationally fixed manner. In order that a sensor element (51) can be fitted with a low level of expenditure and such that it takes up as little installation space as possible, it is proposed according to the invention that the sensor element (51) and the gear (20) are connected to one another at contact areas (57, 211).