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, leading to a compromised steering feel for the driver.
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 magnetic shields, where the biasing member biases the driven gear toward the main driving gear via the magnetic shield, reducing sliding resistance and friction, allowing for suitable meshing without increasing torque requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the main driving gear and driven gears are pressed against each other by the biasing member to reduce backlash, then measurement precision is improved, but torque required for operation increases due to friction
Solution Approach 1:
A magnetic shield is introduced as an intermediary component between the biasing member and the driven gear. The biasing member biases the magnetic shield, which in turn biases the driven gear toward the main driving gear. This intermediary structure reduces direct friction contact while maintaining the necessary meshing pressure for precise rotational angle detection.
Solution Approach 2:
The patent replaces direct mechanical contact between the biasing member and driven gear with a magnetic field-based biasing mechanism. The biasing member generates a magnetic field that acts on the magnetic shield, which then exerts a biasing force on the driven gear. This substitution reduces sliding resistance and friction while maintaining the required meshing pressure for accurate backlash elimination and rotational angle measurement.
2Reliability
If the biasing member directly biases the driven gear toward the main driving gear, then suitable meshing is achieved, but sliding resistance increases
Solution Approach 1:
The magnetic shield serves as a mediator that transmits the biasing force from the biasing member to the driven gear. This intermediary structure allows the driven gear to be reliably biased toward the main driving gear for suitable meshing, while the magnetic field-based interaction reduces direct mechanical friction and sliding resistance between the biasing member and driven gear.
Solution Approach 2:
The patent substitutes direct mechanical biasing with a magnetic field-based biasing system. The biasing member generates a magnetic field that acts on the magnetic shield, which then biases the driven gear. This replacement of direct mechanical contact with magnetic field interaction reduces sliding resistance and energy loss while maintaining reliable gear meshing.
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, maintaining suitable meshing between the main driving gear and driven gears while reducing the coefficient of friction, thereby enhancing steering feel and precision in rotational angle detection.
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
Implementation Method 2
The rotational angle sensor is configured to generate an electric signal based on rotation of the driven gear
Data Source
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AI summary
A sensor device includes a main driving gear (52), a driven gear (53, 54), a biasing member (85), a support member (55), a rotational angle sensor (62, 63), and a magnetic shield (75, 76). The driven gear includes a gear portion (71, 73) and a shaft portion (72, 74). The shaft portion is provided with a permanent magnet. The biasing member (85) 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.