Dual Rotation Angle Sensor Layout With Electromagnetic Decoupling

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Solution Overview

Problem

Existing sensor arrangements with rotational angle sensors face issues of complex signal evaluation due to gear-based motion transmission, which is error-prone and requires a large installation space, and suffer from interference between inductive and magnetoresistive or Hall sensors, leading to limited accuracy and potential damage.

Innovation Solution

A compact sensor arrangement where the magnetoresistive element or Hall sensor is positioned within a circular disk, and the modulator within a circular ring, with a designated zone for electromagnetic decoupling to prevent interference, using a printed circuit board to minimize signal interference and reduce spatial requirements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If a gear mechanism is used to transmit rotary motion between rotors, then the rotational speed can be increased, but the device complexity and reliability deteriorate due to error-prone motion transmission and potential mechanical failure

Engineering Contradiction:
Improverotational speedVSAvoidreliability
Core Design Contradiction:
SpeedVSReliability

Solution Approach 1:

The patent replaces the mechanical gear transmission system with an electromagnetic field-based sensor system. The first rotational angle sensor uses an antenna and modulator to detect rotor position, while the second sensor uses a magnet and magnetoresistive element or Hall sensor. This substitution eliminates mechanical gears, teeth, and associated transmission components, thereby eliminating mechanical failure modes such as dirt blocking, wear, and damage while maintaining the ability to achieve different rotational speeds through electronic signal processing.

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

Solution Approach 2:

The patent extracts and removes the gear mechanism from the sensor arrangement, eliminating the intermediate mechanical transmission component. By directly mounting both rotors to the same shaft, the design extracts the unnecessary complexity of motion transmission while retaining the functional requirement of measuring rotational position and speed through electromagnetic sensing.

Inventive Principle:
Principle #2Taking out (Extraction)

2Adaptability or versatility

If two rotors are accommodated in the sensor arrangement, then the functional requirements are met, but the installation space increases

Engineering Contradiction:
Improvefunctional capabilityVSAvoidinstallation space
Core Design Contradiction:
Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The patent merges the two rotors into a single common rotor structure that is directly coupled to the drive shaft. Both the first rotational angle sensor (with antenna and modulator) and the second rotational angle sensor (with magnet and magnetoresistive element or Hall sensor) share the same rotor body and rotation axis. This consolidation eliminates the need for separate rotors, gear mechanisms, and associated mounting spaces, thereby significantly reducing the overall installation footprint while maintaining the ability to independently measure rotational position for both sensor systems.

Inventive Principle:
Principle #5Merging (Combining)

3Measurement precision

If inductive sensor and magnetoresistive or Hall sensor are combined, then the measurement accuracy is improved, but electromagnetic interference between sensors increases

Engineering Contradiction:
Improvemeasurement accuracyVSAvoidelectromagnetic interference
Core Design Contradiction:
Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The patent introduces a magnetically permeable material as an intermediary element positioned between the inductive sensor components (antenna and modulator) and the magnetoresistive element or Hall sensor. This intermediary material serves as a magnetic shield that directs and contains the magnetic field generated by the magnet, preventing it from interfering with the inductive sensor's electromagnetic field. Simultaneously, it ensures that the magnetic field reaches the magnetoresistive element or Hall sensor for accurate position detection, thereby resolving the electromagnetic interference issue while maintaining measurement accuracy for both sensor types.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 effectively prevents mutual disturbances between sensors, ensuring accurate measurement while reducing the overall size and vulnerability to errors, thereby enhancing the reliability and compactness of the sensor assembly.

Implementation Method 1

the first rotational angle sensor having an antenna (12) comprised by the stator and a modulator (22) comprised by the rotor

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

the second rotational angle sensor having a magnet (23) and a magnetoresistive element (13) or a hall sensor comprised by the stator

Methodology Applied
Scientific EffectMagnetoresistance: Magnetoresistance

Implementation Method 3

the second rotational angle sensor having a magnet (23) and a magnetoresistive element (13) or a hall sensor comprised by the stator

Methodology Applied
Scientific EffectHall effect: Hall Effect

Data Source

PatentEP3894791B1Sensor arrangement comprising two rotation angle sensors of different types
Publication Date: 2024.06.05 HELLA GMBH & CO KGAA
  • EP3894791B1 patent drawingFigure 1
  • EP3894791B1 patent drawingFigure 2
  • EP3894791B1 patent drawingFigure 3~4

AI summary

The invention concerns a sensor assembly comprising two rotational angle sensors of different type, the sensor assembly having a rotor (2) and a stator (1), the first rotational angle sensor having a antenna (12) comprised by the stator (1) and a modulator (22) comprised by the rotor (2), and the second rotational angle sensor having a magnet (23) comprised by the rotor (2) and a magnetoresistive element (13) or a hall sensor comprised by the stator (1).