Stroke Sensor Coil Ferromagnetic Collar Gain

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Solution Overview

Problem

Conventional stroke sensor systems experience a decrease in sensor gain at the end of the stroke, leading to inaccurate measurement of the stroke amount due to a high fitting ratio between the conductor and the coil, which limits the accuracy of the stroke sensor's function.

Innovation Solution

Incorporating a ferromagnetic collar positioned on the opposite side of the coil, maximally fitted to the conductor, increases the sensor gain by enhancing the magnetic field interaction, thereby improving the stroke sensor's performance at the end of the stroke.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If the fitting ratio between the coil and the conductor is increased, then the structural integration is improved, but the sensor gain deteriorates

Engineering Contradiction:
Improvestructural integrationVSAvoidsensor gain
Core Design Contradiction:
Stability of the object's compositionVSMeasurement precision

Solution Approach 1:

A ferromagnetic body is introduced as an intermediary element between the coil and the conductor. This ferromagnetic body enhances the magnetic coupling and flux density in the air gap region, thereby improving sensor gain without requiring a reduction in the fitting ratio between the coil and conductor. The ferromagnetic body acts as a magnetic mediator that amplifies the magnetic interaction while maintaining the structural integration benefits of high fitting ratio.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Volume of moving object

If the fitting ratio between the coil and the conductor is increased, then the device compactness is improved, but the stroke measurement accuracy deteriorates

Engineering Contradiction:
Improvedevice compactnessVSAvoidstroke measurement accuracy
Core Design Contradiction:
Volume of moving objectVSMeasurement precision

Solution Approach 1:

The ferromagnetic body serves as a magnetic intermediary that compensates for the reduced magnetic coupling caused by high fitting ratio. By placing the ferromagnetic body in the air gap region, it concentrates and enhances the magnetic flux, ensuring sufficient magnetic interaction for accurate stroke measurement while maintaining the compact device structure enabled by high fitting ratio.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the magnetic properties parameter by introducing a ferromagnetic material with high permeability into the magnetic circuit. This parameter change enhances the magnetic flux density and coupling efficiency, thereby improving measurement accuracy without altering the physical fitting ratio or device dimensions.

Inventive Principle:
Principle #35Parameter changes

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 configuration significantly increases the sensor gain at the end of the stroke, allowing for more accurate measurement of the stroke amount, overcoming the limitations of conventional systems.

Implementation Method 1

a ferromagnetic body which is arranged on an end position side of the coil when a position of an end portion on one end side of the conductor in a state where a fitting ratio between the conductor and the coil is maximized is defined as the end position, where the ferromagnetic body is located on an opposite side to the conductor with the coil interposed therebetween

Methodology Applied
Scientific EffectMagnetic field interaction: Electromagnetic Induction

Data Source

PatentEP3699451B1Stroke sensor system and shock absorber
Publication Date: 2022.10.12 ASTEMO LTD
  • EP3699451B1 patent drawingFigure 1
  • EP3699451B1 patent drawingFigure 2
  • EP3699451B1 patent drawingFigure 3

AI summary

A stroke sensor system which can detect a change amount of stroke even at an end of the stroke is realized. The stroke sensor system (101) includes a cylinder (10), a coil (81) which is fitted to an axle side of the cylinder, and a collar (95) which is arranged on an end position side of the coil when a position of an axle-side end portion of the cylinder in a state where a fitting ratio between the cylinder and the coil is maximized is defined as the end position, where the collar is located on an opposite side to the cylinder with the coil interposed therebetween.