Torque Detector Magnetic Shield Fixation Without Backlash

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Solution Overview

Problem

Existing torque detectors with magnetic shields face issues of backlash due to dimensional deviations between the magnetic shield and holder, and require additional components like screws for fixation, increasing costs and complexity.

Innovation Solution

A torque detector design where the magnetic shield is fixed without additional components, utilizing engaging members that restrict movement in the counter-insertion direction, ensuring no backlash between the magnetic shield and holder, by using tapered surfaces and elastic engaging members within the engagement grooves.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the magnetic shield is fitted onto the holder by increasing the distance between opposite end portions against spring force, then the magnetic shield can be assembled onto the holder, but dimensional deviations cause backlash after fitting

Engineering Contradiction:
Improveassembly easeVSAvoidbacklash
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The magnetic shield is designed with elastic deformation capability, allowing it to dynamically adjust during assembly. The shield can be elastically expanded to fit over the holder and then automatically returns to its original shape, creating a tight fit that compensates for dimensional variations without causing backlash.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The physical state of the magnetic shield is temporarily changed during assembly by elastically increasing the distance between its end portions. This parameter change allows the shield to be mounted onto the holder, after which it returns to its normal state, ensuring precise positioning without backlash.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If screws or other fastening members are used to fix the magnetic shield to the holder, then the magnetic shield is securely fixed, but the number of components increases resulting in cost increase

Engineering Contradiction:
Improvefixation reliabilityVSAvoidnumber of components
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The magnetic shield serves its own fixation function through its elastic properties. By utilizing the inherent elastic deformation capability of the shield itself, the design eliminates the need for separate fastening components like screws, clips, or adhesives, thereby reducing component count while maintaining secure fixation.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The fixation function is merged with the magnetic shield structure itself. The elastic deformation capability that allows easy assembly also provides the fixation mechanism, combining the mounting and securing functions into a single integrated solution without requiring additional fastening components.

Inventive Principle:
Principle #5Merging (Combining)

3Ease of operation

If the distance between opposite end portions of the magnetic shield is increased for fitting, then assembly is possible, but backlash is caused due to dimensional deviation

Engineering Contradiction:
Improveassembly feasibilityVSAvoidalignment precision
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The elastic deformation capability acts as a cushioning mechanism that anticipates and compensates for dimensional deviations. By allowing controlled elastic expansion during assembly, the system absorbs dimensional variations before they can cause misalignment or backlash, ensuring precise final positioning.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

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

The solution effectively fixes the magnetic shield to the holder without additional components, preventing backlash and reducing costs, while maintaining precise alignment and functionality.

Implementation Method 1

The magnetic shield blocks external magnetic field noises that affect the torque detector

Methodology Applied
Scientific EffectMagnetic shielding: Magnetic Field

Implementation Method 2

The inserting portion has an engaging member that is always engaged with an inner surface of the insertion portion to restrict movement of the inserting portion in a counter-insertion direction

Methodology Applied
Scientific EffectElastic engagement: Elasticity

Data Source

PatentEP3239678B1Torque detector
Publication Date: 2019.01.23 JTEKT CORP
  • EP3239678B1 patent drawingFigure 1
  • EP3239678B1 patent drawingFigure 2~3
  • EP3239678B1 patent drawingFigure 4

AI summary

There is provided a torque detector configured such that a magnetic shield is fixed to a holder without the need for a component for fixation of the magnetic shield, and no backlash is caused between the magnetic shield and the holder after the magnetic shield is fixed to the holder. The torque detector has engagement grooves (50, 51) into which a magnetic shield (40) is to be inserted when the magnetic shield (40) is fitted onto outer peripheral surfaces of a first holder (20A) and a second holder (20B). The magnetic shield (40) has end portions (40a) to be inserted into the engagement grooves (50, 51), and each of the end portions (40a) is provided with engaging members (41a, 41b) that are always engaged with inner surfaces of the engagement grooves (50, 51), respectively, while being inserted into the engagement grooves (50, 51), to restrict movement of the end portions (40a) in the counter-insertion direction.