Rotary Torque Sensor Using Non-Ferromagnetic Coils
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Solution Overview
Problem
Conventional rotary-angle and rotary-torque sensing devices for steering shafts in automobiles are prone to errors in sensing rotary torque due to foreign matter attachment, such as iron powders, affecting accuracy.
Innovation Solution
The proposed rotary-angle and rotary-torque sensing device incorporates a design with a first rotator and second rotator connected via a coupler, featuring a rotary torque sensor and rotary angle sensor, along with a controller that utilizes both sensors to accurately detect rotary torque and angle, employing magnetic sensing elements and gears with specific pole arrangements to minimize errors, and includes a mechanism to detect sensor defects by comparing signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a rotary torque sensor uses magnetic sensing elements and ferromagnetic bodies to detect rotary torque, then the sensing capability is improved, but foreign matter such as iron powders can attach to these components causing measurement errors
Solution Approach 1:
The patent extracts the harmful ferromagnetic materials (magnet and ferromagnetic bodies) from the torque sensing mechanism and replaces them with non-ferromagnetic alternatives. The torque sensor now uses a non-ferromagnetic rotor and stator with winding coils, eliminating the attraction of iron powders and foreign matter while maintaining torque detection capability through electromagnetic induction rather than magnetic attraction.
Solution Approach 2:
The patent employs a simpler, more robust sensor design that is less sensitive to contamination. By using non-ferromagnetic materials and a wound-coil-based detection system, the sensor becomes more resilient to foreign matter attachment, effectively treating the sensing components as durable elements that maintain performance even in contaminated environments.
2Measurement precision
If the sensing device uses multiple sensors and complex signal processing to improve accuracy, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent makes the rotary torque sensor multi-functional by enabling it to detect both rotary torque and rotary angle simultaneously through a single integrated structure. The non-ferromagnetic rotor with winding coils serves dual purposes: detecting torque through electromagnetic induction and detecting angle through the position of the magnetic poles, eliminating the need for separate sensors and reducing overall device complexity.
Solution Approach 2:
The patent merges the torque sensing and angle sensing functions into a single integrated sensor unit. The controller processes signals from the winding coils to derive both torque and angle information, combining multiple sensing capabilities in one device rather than using separate sensors, thereby reducing structural complexity while maintaining measurement precision.
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 design achieves accurate detection of rotary torque with reduced errors, approximately 0.1 degree, and rotary angle with 0.7 degree accuracy, enabling effective control of power steering and braking devices, and can compensate for sensor defects by using the rotary angle sensor to provide torque data, ensuring reliable operation.
Implementation Method 1
magnetic sensing elements 16B and 17B such as AMR (anisotropic magnetic resistance) at places confronting magnets 16A and 17A respectively
Implementation Method 2
magnetic sensing elements 16B and 17B such as AMR (anisotropic magnetic resistance)
Implementation Method 3
magnet 3 is shaped like a cylinder where multiple N-poles and S-poles are alternately and adjoiningly arrayed
Implementation Method 4
magnetisms emitted from magnets 16A and 17A vary due to the rotation, magnetic sensing elements 16B and 17B sense the varying magnetisms
Implementation Method 5
Coupler 12, e.g. torsion bar, is made of steel and shaped like a pole
Implementation Method 6
coupler 12 is provided such that an upper section of coupler 12 adheres to rotator 1 and a lower section thereof adheres to rotator 4
Implementation Method 7
Third rotator 13 includes a spur gear at its underside. First and second sensors 14, 15 include spur gears on their outer walls
Implementation Method 8
Magnetic sensing element 9 includes a Hall element
Data Source
AI summary
A rotary-angle and rotary-torque sensing device includes a first rotator rotating together with a steering shaft, a second rotator rigidly mounted to the first rotator, a rotary torque sensor for sensing rotary torque generated between the first rotator and the second rotator, a first sensor rotating together with the first rotator, a second sensor rotating together with the second rotator, a rotary angle sensor for sensing rotary angles of the first sensor and the second sensor, and a controller for detecting rotary torque by using the rotary torque sensor and the rotary angle sensor.