Cam Mechanism Torque Detection for Power Steering
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Solution Overview
Problem
Existing torque detection devices for power steering are complex in structure and susceptible to external factors and bending forces, with limitations in accuracy and susceptibility to lost motion during torsional deformation.
Innovation Solution
A torque detection device utilizing a cam mechanism to convert torque into thrust force, which is then detected by a pressure sensor, eliminating the need for planetary gear mechanisms and sensing coils, and utilizing an incompressible fluid to reduce susceptibility to external factors and lost motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a planetary gear mechanism is used for torque detection, then torque can be detected, but the structure becomes complicated
Solution Approach 1:
The patent replaces the planetary gear mechanism with a cam mechanism that converts rotational torque into linear thrust force, which is then detected by a pressure sensor. This substitution simplifies the overall structure by eliminating complex gear components while maintaining accurate torque detection capability through the cam mechanism's geometric transformation.
Solution Approach 2:
The patent introduces an incompressible fluid as an intermediary medium between the cam mechanism and the pressure sensor. The fluid transmits the thrust force generated by the cam mechanism to the pressure sensor, enabling indirect torque measurement while isolating the detection system from mechanical complexity and external factors.
2Measurement precision
If a magnetostrictive type torque sensor is used, then torque can be detected, but the device is susceptible to bending force influences
Solution Approach 1:
The patent replaces the magnetostrictive sensing system with a purely mechanical cam mechanism coupled to a pressure sensor. This substitution eliminates sensitivity to bending forces by using a cam profile that converts only rotational torque into measurable thrust force, while the incompressible fluid transmission further isolates the detection from external mechanical disturbances.
Solution Approach 2:
The incompressible fluid serves as a mediator that transmits force while filtering out the effects of bending forces and external disturbances. The fluid's incompressibility ensures that only true thrust force from the cam mechanism is transmitted to the pressure sensor, eliminating false readings from bending forces.
3Measurement precision
If a torsion bar is used to detect torque, then torque can be measured, but lost motion occurs during torsional deformation
Solution Approach 1:
The patent replaces the torsion bar-based detection system with a cam mechanism that converts torque to linear motion. This substitution eliminates lost motion by using the cam's geometric profile to ensure positive, continuous force transmission to the pressure sensor, avoiding the elasticity and energy loss associated with torsional deformation.
Solution Approach 2:
The incompressible fluid acts as an intermediary that transmits force without energy loss or lost motion. Unlike the torsion bar which undergoes elastic deformation, the fluid transmission system maintains constant force transmission, eliminating the lost motion problem while preserving 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 provides a compact, accurate, and robust torque detection system that is less influenced by external factors and bending forces, reducing structural complexity and lost motion, while ensuring precise torque measurement for power steering assistance.
Implementation Method 1
a cam mechanism which is provided between the input shaft and the output shaft and by which the torque generated between the input shaft and the output shaft is converted into a thrust force
Implementation Method 2
a pressure sensor for detecting the thrust force into which the torque is converted by the cam mechanism
Implementation Method 3
utilizing an incompressible fluid to reduce susceptibility to external factors and lost motion
Data Source
AI summary
A torque detection device for a power steering which is less liable to be influenced by external factors or by a bending force exerted on a shaft. In the torque detection device, a torque is generated between an input shaft, which is turned interlockedly with a steering handle for operating the traveling direction of a vehicle, and an output shaft turned interlockedly with the input shaft so as to steer the vehicle. An assisting force is exerted on the output shaft by an assisting unit that is determined based on the detection result. The torque detection device is provided between the input shaft and the output shaft and includes a cam mechanism by which a torque generated between the input shaft and the output shaft is converted into a thrust force, and a pressure sensor for detecting the thrust force into which the torque is converted by the cam mechanism.