Steering Torque Sensor Using Magnetic Flux Modulation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing vehicle steering systems face challenges in accurately sensing torque applied to the steering wheel independently of its rotational position, which affects the precision of steering assist provided by power steering systems.
Innovation Solution
A torque sensor apparatus is designed with an input and output shaft connected by an elastically deformable torsion bar, featuring a magnet and a magnetic field varying member that moves within the magnetic field of a sensor to provide an analog output voltage indicative of torque applied, allowing for accurate torque measurement regardless of the steering wheel's rotational position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a Hall effect sensor with ferromagnetic collectors is used to sense steering column torsion, then torque sensing capability is provided, but the measurement becomes dependent on the rotational position of the steering wheel
Solution Approach 1:
A magnetic field varying member (magnetic flux modulator) is introduced as an intermediary element between the steering shaft and the Hall effect sensor. This member translates the rotational position information into magnetic flux variations that independently encode torque information, allowing the sensor to measure torque without being affected by the steering wheel's angular position
Solution Approach 2:
The patent replaces direct mechanical coupling between the steering shaft and sensor with a magnetic field-based interaction system. The magnetic field varying member converts mechanical rotation into magnetic flux variations, eliminating the need for direct mechanical connection and enabling position-independent torque measurement
2Measurement precision
If an elastically deformable member is used to connect input and output shafts, then relative rotation indicative of torque is enabled, but the structural complexity increases
Solution Approach 1:
The magnetic field varying member serves multiple functions simultaneously: it acts as a torque transmission element, a magnetic flux modulator, and a position-independent sensing enabler. This multi-functionality reduces the need for separate components and simplifies the overall sensor apparatus structure
Solution Approach 2:
The patent combines the magnetic field varying member with the sensor housing and mounting structures, integrating multiple functions into a unified component assembly. This merging approach reduces the number of discrete parts and simplifies the overall device structure 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
The solution enables precise and independent measurement of torque applied to the steering wheel, enhancing the accuracy of steering assist in vehicle power steering systems by providing a proportional and linear voltage output corresponding to torque changes, thereby improving the overall steering performance.
Implementation Method 1
a magnetic field varying member positioned in a magnetic field of the magnet, where the magnetic field varying member is movable in a longitudinal direction generally parallel to the rotational axis to vary a magnetic flux between the magnet and the sensor
Implementation Method 2
A magnet is located adjacent and in radially spaced relation to the sensor... A sensor provides an analog output voltage in response to a sensed magnetic field
Data Source
AI summary
A sensor apparatus for a power steering system on a vehicle, where the apparatus includes an input shaft for receiving a steering input and for rotating about a rotational axis. An output shaft is provided for transmitting the steering input from the input shaft to a steered wheel assembly of the vehicle. A torque transmitting member connects between the input shaft and the output shaft for transmitting a torque from the input shaft to the output shaft. A sensor provides an analog output voltage in response to a sensed magnetic field. A magnet is located adjacent and in radially spaced relation to the sensor, and a magnetic field varying member is positioned in a magnetic field of the magnet, where the magnetic field varying member is movable in a longitudinal direction generally parallel to the rotational axis to vary a magnetic flux between the magnet and the sensor in response to relative movement between the input shaft and the output shaft.