Shaft Torque Sensor Holder with Elastic Traction

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Solution Overview

Problem

Existing torque measurement systems for shafts in vehicles face static and dynamic errors due to misalignment and manufacturing tolerances, leading to inaccurate sensor readings.

Innovation Solution

A measuring arrangement with a sensor holder and force element that securely attaches to the shaft's outer peripheral surface, minimizing air gaps and compensating for errors in concentricity and alignment, using elastic force elements and holding legs to maintain stable position and orientation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the sensor is mounted on a sensor holder outside the shaft with a certain distance, then the sensor can be protected and easily mounted, but static measurement deviations occur due to air gap variations

Engineering Contradiction:
Improvesensor mounting easeVSAvoidtorque measurement accuracy
Core Design Contradiction:
Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent applies the dynamics principle by making the sensor holder movable relative to the shaft through an elastic element (spring). The sensor holder can dynamically adjust its position to maintain optimal alignment with the shaft during rotation, compensating for centrifugal forces and alignment errors. This dynamic adjustment resolves the contradiction by allowing easy initial mounting while maintaining measurement precision during operation.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the physical state and position parameters of the sensor holder by using an elastic element that allows the holder to move radially and axially. This parameter change enables the sensor to maintain a consistent air gap with the shaft despite rotational forces, thereby improving measurement accuracy while preserving ease of mounting.

Inventive Principle:
Principle #35Parameter changes

2Stability of the object's composition

If the sensor holder is fixedly mounted, then the structure is simple and stable, but dynamic errors occur due to errors in concentricity and coaxiality during shaft rotation

Engineering Contradiction:
Improvesensor holder stabilityVSAvoidsensor signal accuracy
Core Design Contradiction:
Stability of the object's compositionVSMeasurement precision

Solution Approach 1:

The patent transforms the fixed sensor holder into a dynamic system where the holder can move relative to the shaft. The elastic element enables the sensor holder to automatically compensate for centrifugal forces and maintain proper alignment during rotation, eliminating dynamic errors while preserving structural stability through the elastic connection.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent replaces the rigid mechanical fixed mounting system with an elastic mechanical system. The spring element substitutes for rigid constraints, allowing the sensor holder to flex and adjust its position dynamically, thereby eliminating alignment errors caused by fixed mounting imperfections.

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

3Manufacturing precision

If a large air gap exists between sensor and shaft, then manufacturing tolerances are easier to accommodate, but measurement accuracy decreases due to enlarged air gap

Engineering Contradiction:
Improveassembly tolerance toleranceVSAvoidmagnetic field measurement accuracy
Core Design Contradiction:
Manufacturing precisionVSMeasurement precision

Solution Approach 1:

The patent uses the dynamic capability of the elastic element to maintain a consistently small air gap between the sensor and shaft during rotation. The sensor holder can dynamically adjust its position to compensate for manufacturing tolerances, thereby maintaining both ease of assembly and high measurement accuracy.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the air gap parameter from a fixed large value to a dynamically maintained small value. The elastic element enables continuous adjustment of the sensor holder position, keeping the air gap minimal despite manufacturing variations, thus improving measurement accuracy without compromising assembly ease.

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

This configuration ensures accurate and reproducible torque measurements by maintaining a consistent air gap and correcting for angular errors, resulting in improved measurement reliability and precision.

Implementation Method 1

The effect of magnetostriction, magnetoelasticity, or inverse magnetostriction or magnetoelasticity can be utilized for this purpose. This effect is based on the deformation of magnetic, especially ferromagnetic, materials as a result of an applied magnetic field.

Methodology Applied
Scientific EffectInverse magnetostriction: Magnetostriction

Implementation Method 2

The effect of magnetostriction, magnetoelasticity, or inverse magnetostriction or magnetoelasticity can be utilized for this purpose.

Methodology Applied
Scientific EffectMagnetoelasticity: Magnetoelastic Effects

Implementation Method 3

In an advantageous embodiment of the measuring arrangement according to the invention, the at least one force element is designed as an elastic force element, especially as a spring element or the like.

Methodology Applied
Scientific EffectElastic force: Elasticity

Data Source

PatentEP3325930B1Measuring assembly for measuring the torque on a shaft, crank drive and vehicle
Publication Date: 2020.07.29 ROBERT BOSCH GMBH
  • EP3325930B1 patent drawingFigure 1
  • EP3325930B1 patent drawingFigure 2~3
  • EP3325930B1 patent drawingFigure 4~5

AI summary

The present invention relates to a measuring assembly (100) for measuring the torque (M) on a shaft (16) and in particular the torsional moment of the shaft (16). Said measuring assembly comprises a sensor device (30), designed to measure a magnetic field (H) sustained or generated by the shaft (16), a sensor holder (20) for holding the sensor device (30) and for arrangement of the sensor device (30) in relation to a region (17a) of an outer peripheral surface (17) of the shaft (16), and at least one force element (41), designed to hold the sensor holder (20) in place in relation to the region (17a) of the outer peripheral surface (17) of the shaft (16) by a force applied thereto. The at least one force element (41) is designed to exert a traction force onto the sensor holder (20) such that the shaft (16) is used to the region (17a) of the outer peripheral surface (17) due to the traction force of the sensor holder (20).