Rotational Angle Sensor Gear Biasing With Magnetic Shield

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Solution Overview

Problem

Existing rotational angle sensor devices for vehicles experience increased torque requirements due to friction generated when pressing the main driving gear and driven gears together to reduce backlash, which affects the steering feel and stability.

Innovation Solution

A sensor device configuration that includes a main driving gear, driven gears, a biasing member, a support member, a rotational angle sensor, and a magnetic shield, where the biasing member biases the driven gear toward the main driving gear via the magnetic shield, reducing sliding resistance and maintaining suitable meshing while minimizing torque requirements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the main driving gear and driven gears are pressed against each other by the biasing member, then backlash is reduced and meshing precision is improved, but friction is generated and torque required for steering is increased

Engineering Contradiction:

Improvemeshing precisionVSAvoidtorque

Core Design Contradiction:

Manufacturing precisionVSForce

Solution Approach 1:

The magnetic shield acts as an intermediary component between the biasing member and the driven gear. The biasing member biases the magnetic shield toward the main driving gear, and the magnetic shield in turn biases the driven gear toward the main driving gear. This intermediary arrangement reduces direct friction between the biasing member and the driven gear, thereby reducing the torque required for steering while maintaining meshing precision.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the biasing member directly biases the driven gear toward the main driving gear, then meshing is secured, but sliding resistance increases and torque requirement increases

Engineering Contradiction:

Improvemeshing stabilityVSAvoidsteering operation

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The magnetic shield serves as a mediator that transmits the biasing force from the biasing member to the driven gear indirectly. This reduces the sliding resistance between the biased component and the biasing member, making steering operation easier while maintaining reliable meshing between the gears.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Force

If the magnetic shield is introduced between the biasing member and driven gear, then sliding resistance is reduced and torque requirement is suppressed, but device complexity increases

Engineering Contradiction:

ImprovetorqueVSAvoidstructure complexity

Core Design Contradiction:

ForceVSDevice complexity

Solution Approach 1:

The magnetic shield performs multiple functions simultaneously: it acts as a magnetic shield to protect the rotational angle sensor from magnetic interference, serves as a biased component to transmit force from the biasing member, and reduces sliding resistance to lower torque requirements. By combining multiple functions into a single component, the overall device complexity is minimized.

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Object-affected harmful factors

If the magnetic shield rotatably surrounds the shaft portion, then magnetic shielding is provided for the rotational angle sensor, but sliding resistance between magnetic shield and driven gear must be minimized

Engineering Contradiction:

Improvemagnetic interferenceVSAvoidrotation smoothness

Core Design Contradiction:

Object-affected harmful factorsVSEase of operation

Solution Approach 1:

The magnetic shield is designed with specific local properties: it rotatably surrounds the shaft portion to provide magnetic shielding where needed, while its interaction surfaces are optimized to minimize sliding resistance. The biasing force is applied in a specific direction to maintain meshing precision without excessive friction, ensuring smooth rotation while protecting the sensor.

Inventive Principle:

Principle #3Local quality

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 solution effectively suppresses the increase in torque required to rotate the rotary shaft, ensuring suitable meshing between the main driving gear and driven gears while improving the precision of rotational angle detection and reducing the number of parts in the sensor device.

Implementation Method 1

The biasing member biases the driven gear toward the main driving gear by biasing the magnetic shield toward the main driving gear

Methodology Applied

Scientific EffectMagnetic biasing: Magnetism

Implementation Method 2

The rotational angle sensor is configured to generate an electric signal based on rotation of the driven gear

Methodology Applied

Scientific EffectMagnetic field detection: Magnetic Field

Data Source

PatentUS11180193B2Sensor device

Publication Date: 2021.11.23 JTEKT CORP

AI summary

A sensor device includes a main driving gear, a driven gear, a biasing member, a support member, a rotational angle sensor, and a magnetic shield. The driven gear includes a gear portion and a shaft portion. The shaft portion is provided with a permanent magnet. The biasing member is configured to bias the driven gear toward the main driving gear. The support member supports the driven gear and the biasing member. The magnetic shield rotatably surrounds the shaft portion. The biasing member biases the driven gear toward the main driving gear by biasing the magnetic shield toward the main driving gear. The sliding resistance between the magnetic shield and the driven gear is lower than the sliding resistance between the magnetic shield and the biasing member.