Yoke Assembly Positioning via Intermediary Pin for Torque Detection

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Solution Overview

Problem

The existing manufacturing method for yoke assemblies in torque detecting devices often results in molding defects due to radial displacement of yoke rings, leading to inaccurate detection of steering torque, as the positioning of yoke rings in the mold is prone to error, causing the pole claws to be covered by the resin, which interferes with magnetic flux change detection.

Innovation Solution

The method involves positioning yoke rings with specific axial holes for precise alignment using a common positioning pin, ensuring the pole claws are alternately arranged, and integrating them with a resin retaining cylinder to prevent radial displacement during molding, thus maintaining concentricity and exposing all pole claws for accurate torque detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a gauge is inserted between pole claws to position yoke rings in the mold, then the interval between pole claws can be secured, but the yoke rings may be pushed radially causing displacement and molding defects

Engineering Contradiction:
Improvepositioning accuracy of yoke ringsVSAvoidconcentricity of yoke assembly
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

A positioning pin is introduced as an intermediary tool to position the yoke rings. The positioning pin fits into positioning holes formed in the yoke rings, providing a reliable reference that prevents radial displacement during molding while maintaining concentricity between the yoke rings and the retaining cylinder.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

Positioning holes are pre-formed in the yoke rings before molding. These positioning holes are created at specific locations to receive the positioning pin, ensuring that the yoke rings are correctly positioned in the mold before the resin is injected, thereby preventing radial displacement during the molding process.

Inventive Principle:
Principle #10Preliminary action

2Manufacturing precision

If yoke rings are positioned using a gauge inserted from above, then the circumferential interval can be controlled, but radial displacement occurs causing pole claws to be covered by resin

Engineering Contradiction:
Improvecircumferential positioning of pole clawsVSAvoidmolding process reliability
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The positioning pin serves as a mediator that simultaneously controls both the circumferential interval and radial position of the yoke rings. By fitting into positioning holes at predetermined locations, it ensures proper spacing while preventing the yoke rings from being pushed radially during molding, thus avoiding coverage of pole claws by resin.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The conventional gauge insertion method is replaced with a positioning pin system that uses pre-formed positioning holes. This substitution eliminates the mechanical pushing action that causes radial displacement while maintaining precise circumferential positioning, thereby improving molding process reliability.

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

3Manufacturing precision

If positioning holes are formed in yoke rings for pin insertion, then accurate positioning is achieved, but the device complexity increases

Engineering Contradiction:
Improvepositioning accuracy of yoke ringsVSAvoidyoke assembly structure
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The positioning function is segmented into distinct positioning holes formed in the yoke rings, separated from the main body structure. This allows the positioning features to be created independently during manufacturing and simplifies the overall assembly process, as the positioning holes are integrated into the yoke ring fabrication rather than requiring additional separate components.

Inventive Principle:
Principle #1Segmentation

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 approach ensures accurate positioning of yoke rings, preventing molding defects and enhancing the accuracy of torque detection by maintaining the concentricity of the yoke assembly, allowing for precise measurement of rotational torque applied to the shafts.

Implementation Method 1

a cylindrical magnet having a plurality of magnetic poles arranged on an outer circumference

Methodology Applied
Scientific EffectMagnetic field: Magnetic Field

Implementation Method 2

the magnetic flux generated in the two yoke rings changes according to this positional change, it is possible to find the steering torque by detecting the change in the magnetic flux

Methodology Applied
Scientific EffectMagnetic flux change: Magnetic Field

Data Source

PatentEP1870684B1Torque detecting device and manufacturing method of yoke assembly
Publication Date: 2009.08.26 JTEKT CORP
  • EP1870684B1 patent drawingFigure 1
  • EP1870684B1 patent drawingFigure 2
  • EP1870684B1 patent drawingFigure 3

AI summary

A yoke assembly (5) is constructed by retaining integrally a yoke ring (50) having positioning holes (54, 54) aligned with pole claws (51, 51 ...) arranged equally on the inner circumference and a yoke ring (50) having positioning holes (55, 55) aligned with the space between pole claws (51, 51...) arranged equally on the inner circumference by a retaining cylinder (52) made of a resin. The retaining cylinder (52) has a pin hole (56) remaining after pulling out a common positioning pin inserted into the positioning holes (54, 55) during molding.