Torque Sensor Coil Bobbin Axial Pressing Mechanism

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Solution Overview

Problem

Conventional torque detection devices cause deformation of detection coils when held in yokes, leading to variations in electrical characteristics due to bending of coil bobbins.

Innovation Solution

The torque detection device uses radially projecting pressing portions on the flange portion of coil bobbins to axially press the coils into yokes, stabilizing their position without direct deformation, thereby reducing coil deformation and maintaining consistent electrical characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the end faces of coil bobbins are bent and held by protrusions formed on the peripheral edge portions of these end faces, then the coil bobbins can be held in the yokes, but the electrical characteristics of the detection coils change and vary due to deformation of the detection coils upon the bending

Engineering Contradiction:
Improveholding stabilityVSAvoidelectrical characteristic consistency
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent introduces an intermediary structure (pressing portion with lug portion) between the holding mechanism and the coil bobbin end face. The lug portion of the pressing portion presses the coil bobbin from the side, preventing direct contact and deformation between the protrusions and the end face, thus maintaining electrical characteristic consistency while achieving stable holding

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent divides the holding function into two separate components: the protrusions provide the holding function, while the pressing portions with lug portions provide the pressing function. This segmentation allows each component to perform its specific function without causing deformation to the coil bobbin end face

Inventive Principle:
Principle #1Segmentation

2Stability of the object's composition

If protrusions are formed on the peripheral edge portion of the end face of coil bobbins to hold the coil bobbins between yokes and a cover yoke, then the coil bobbins can be secured in position, but the end faces of the coil bobbins bend causing deformation of detection coils

Engineering Contradiction:
Improvepositional stabilityVSAvoidcoil bobbin end face shape
Core Design Contradiction:
Stability of the object's compositionVSShape

Solution Approach 1:

The pressing portion acts as an intermediary that presses the coil bobbin from the side through its lug portion, preventing the protrusions from directly contacting and deforming the end face of the coil bobbin. This intermediary mechanism maintains both positional stability and shape integrity

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

Instead of pressing the coil bobbin from the end face (which causes deformation), the patent inverts the pressing direction by using the lug portion to press from the side of the coil bobbin, thereby achieving the same holding effect without deforming the end face

Inventive Principle:
Principle #13The other way round (Inversion)

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 allows for highly reliable steering assist control in electric power steering devices and vehicles by minimizing coil deformation and maintaining stable electrical characteristics.

Implementation Method 1

pressing portions formed in the flange portion of each coil bobbin to project radially outwards from the radial outer end portion of this flange portion

Methodology Applied
Scientific EffectRadial projection and axial pressing mechanism: Mechanical Force

Data Source

PatentEP3242117B1Torque detecting device, electric power steering device, and vehicle
Publication Date: 2020.06.17 NSK LTD
  • EP3242117B1 patent drawingFigure 1
  • EP3242117B1 patent drawingFigure 2
  • EP3242117B1 patent drawingFigure 3

AI summary

To provide a torque detection device which allows less deformation of detection coils than in the conventional techniques in axially pressing and holding in yokes, coil bobbins around which the detection coils are wound. A torque sensor (TS) includes a pair of coils (13a, 13b), coil bobbins (18Aa, 18Ab) around which the coils (13a, 13b) are respectively wound, yokes (15a, 15b) which respectively hold the coil bobbins (18Aa, 18Ab), one yoke cover (14) fitted by pressing into inner diameters of the yokes (15a, 15b), and pressing portions (18c) which are formed to project radially and outward at a plurality of circumferential positions of a radial outer end portion of respective flange portions (18b) of the coil bobbins (18Aa, 18Ab), and act between the coil bobbins (18Aa, 18Ab) to axially press the coil bobbins (18Aa, 18Ab) during assembly.