Indirect Torque Sensor via Bearing Force Detection

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Solution Overview

Problem

Existing torque sensors for rotating shafts are costly and application-specific, making them impractical for widespread use due to their complex design and the need for custom integration with the shaft, limiting their application and cost-effectiveness.

Innovation Solution

A sensor arrangement that indirectly measures torque by detecting bearing forces using piezoresistive sensor elements, which can be compactly designed and produced inexpensively, allowing for integration into existing systems with minimal structural changes, and featuring a sensor body with a sensor element pressed into a supporting structure to record material expansion or compression caused by bearing forces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If co-rotating sensors are integrated into the drive shaft to measure torsion directly, then measurement precision is improved, but device complexity and manufacturing cost increase significantly

Engineering Contradiction:
Improvetorque measurement precisionVSAvoidsensor integration complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent introduces bearing forces as an intermediary measurement target. Instead of measuring shaft torsion directly, the sensor measures the bearing forces that result from torque transmission. This intermediary approach allows indirect torque measurement using a simpler sensor configuration mounted on the housing rather than integrated into the rotating shaft, thereby reducing device complexity while maintaining measurement capability.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent creates a simplified sensor arrangement that copies the measurement function of complex co-rotating sensors. By measuring bearing forces that are proportional to torque, the system achieves torque measurement without requiring the full complexity of integrated co-rotating sensor systems, including their strain gauges, transformers, and signal processing electronics.

Inventive Principle:
Principle #26Copying

2Measurement precision

If magnetoelastic sensors are integrated into the shaft, then torque measurement capability is improved, but adaptability to different applications decreases due to custom design requirements

Engineering Contradiction:
Improvetorque detection capabilityVSAvoidapplication-specific design requirement
Core Design Contradiction:
Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent separates the measurement function from the shaft structure. The sensor arrangement is divided into independent components: bearing force sensors mounted on the housing and a separate torque calculation unit. This segmentation allows the sensor to be designed as a standalone module that can be applied to different shaft systems without custom integration, significantly improving adaptability while maintaining torque measurement capability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The sensor arrangement is designed to be universally applicable to different shaft systems. By measuring bearing forces that are generated in any torque-transmitting shaft-bearing system, the same sensor design can be used across multiple applications and industries, eliminating the need for application-specific custom design while preserving accurate torque detection.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Ease of manufacture

If static transducers are used for torque measurement, then manufacturing cost is reduced, but the sensor arrangement cannot measure torque on rotating shafts

Engineering Contradiction:
Improvemanufacturing costVSAvoidrotating shaft measurement capability
Core Design Contradiction:
Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The patent replaces the need for rotating mechanical sensor systems with a stationary sensor arrangement. By measuring bearing forces on the stationary housing rather than using co-rotating sensors, the system achieves rotating shaft torque measurement capability using static, non-rotating components. This substitution maintains low manufacturing costs while extending measurement capability to rotating shafts.

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

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

Enables cost-effective and flexible measurement of torque on rotating shafts without the need for complex design modifications, allowing for use in various applications with precise calculation of torque from bearing forces, and accommodating different positions and angles for enhanced accuracy.

Implementation Method 1

The sensor has at least one sensor body 20 with an outer contour 24, which carries a corresponding sensor element 30 and is pressed into a receiving bore 12, the sensor element 30 having a predetermined distance and a predetermined angle for bearing 7 has

Methodology Applied
Scientific EffectPiezoresistive effect: Piezoresistive Effect

Data Source

PatentEP3250896B1Sensor arrangement for indirect detection of a torque of a rotatably mounted shaft
Publication Date: 2019.11.27 ROBERT BOSCH GMBH
  • EP3250896B1 patent drawingFigure 1
  • EP3250896B1 patent drawingFigure 2~3
  • EP3250896B1 patent drawingFigure 4

AI summary

The invention relates to a sensor arrangement (1) for indirect detection of a torque of a rotatably mounted shaft (5), having a sensor (10) which comprises at least one sensor element (30) arranged in the surroundings of a bearing (7) of the shaft (5), said bearing being linked to a supporting structure (3), and which sensor element detects a proportion of a bearing force (FL) acting in a predetermined direction, from which the torque of the shaft (5) can be calculated. According to the invention, the sensor (10) has at least one sensor body (20) with an outer contour which supports a corresponding sensor element (30) and is pressed into a receiving hole (12), wherein the sensor element (30) has a predetermined distance and a predetermined angle to the bearing (7).