Power Steering Torque Sensor Segmentation
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Solution Overview
Problem
Conventional auto-steerable power steering devices face challenges in achieving high accuracy in both torque sensor detection and rotary valve control due to the differing rigidity requirements of torsion bars for these functions.
Innovation Solution
The power steering device employs separate torsion bars for torque detection and rotary valve control, allowing for optimized stiffness settings for each, along with a torque sensor system using resolvers to accurately calculate steering torque and control the rotary valve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single torsion bar is used for both torque detection and rotary valve control, then the device complexity is reduced, but the measurement precision of the torque sensor and the manufacturing precision of the rotary valve control cannot both be optimized
Solution Approach 1:
The patent divides the single torsion bar function into two separate torsion bars: a first torsion bar (12) dedicated to torque detection with optimized stiffness for the torque sensor, and a second torsion bar (14) dedicated to rotary valve control with optimized stiffness for valve opening/closing. This segmentation allows each torsion bar to be independently optimized for its specific function, resolving the contradiction between device complexity and measurement precision.
2Measurement precision
If the torsion bar stiffness is optimized for torque detection, then the measurement precision improves, but the rotary valve control precision deteriorates
Solution Approach 1:
By segmenting the torsion bar functionality into two separate components, each with independently optimized stiffness values, the patent enables the first torsion bar to be optimized for torque sensor accuracy while the second torsion bar is optimized for rotary valve control accuracy, eliminating the trade-off between these two precision requirements.
Solution Approach 2:
The patent applies different stiffness characteristics to different parts of the steering shaft system: the first torsion bar has stiffness optimized for detection purposes, while the second torsion bar has stiffness optimized for control purposes. This local differentiation of properties allows each subsystem to operate at optimal precision.
3Manufacturing precision
If the torsion bar stiffness is optimized for rotary valve control, then the manufacturing precision of valve control improves, but the measurement precision of the torque sensor deteriorates
Solution Approach 1:
The patent resolves this contradiction by creating two separate torsion bars with independently optimized stiffness values. The first torsion bar is designed with stiffness suitable for torque sensor operation, while the second torsion bar is designed with stiffness suitable for rotary valve control, allowing both precision requirements to be met simultaneously without compromise.
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 enables high accuracy detection and control of the rotary valve, improving the overall performance and reliability of the power steering system.
Implementation Method 1
a first torsion bar (12) connected to the input shaft (11) and the intermediate shaft (13)
Implementation Method 2
a second torsion bar (14) connected to the intermediate shaft (13) and the output shaft (15)
Implementation Method 3
a first rotation angle sensor (51) provided on the input shaft (11) and detecting a rotation angle of the input shaft (11), a second rotation angle sensor (52) provided on the intermediate shaft (13) and detecting a rotation angle of the intermediate shaft (13)
Implementation Method 4
a control valve (19) which selectively feeds an operating fluid into the first or second pressure chamber
Data Source
AI summary
A steering shaft 10 is constructed by an input shaft 11, an intermediate shaft 13 connected to the input shaft 11 through a first torsion bar 12 and an output shaft 15 connected to the intermediate shaft 13 through a second torsion bar 14, and around the input shaft 11, there is provided a first resolver 51 for detecting a rotation angle of the input shaft 11 and around the intermediate shaft 13, there is provided a second resolver 52 for detecting a rotation angle of the intermediate shaft 13, and the first and second resolvers 51 and 52 are arranged to constitute a torque sensor TS that detects a steering torque.