Steering Angle Sensor Elastic O-Ring Absorbs Shaft Inclination
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Solution Overview
Problem
Existing steering angle sensors for electric power steering systems suffer from detection errors due to the direct connection of the first gear to the steering shaft, which causes transmission issues when the steering shaft is inclined, leading to inaccurate steering angle measurements.
Innovation Solution
A steering angle sensor design that includes a first gear with an annular body and toothed portion, a second gear with a magnetic member, and a third gear with a magnetic member, where the elastic O-ring is compressed between the steering shaft and the first gear to absorb inclination, ensuring stable rotation transmission and reducing detection errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the first gear is directly connected to the steering shaft to rotate together, then the rotation transmission is simple and reliable, but when the steering shaft is inclined, the first gear is inclined following the steering shaft, which deteriorates the transmission manner of rotation and causes detection error
Solution Approach 1:
The patent introduces an elastic member as an intermediary element between the steering shaft and the first gear. This elastic member acts as a mediator that decouples the direct mechanical connection, allowing the first gear to maintain its rotational function while filtering out the inclination effects from the steering shaft. The elastic member absorbs the inclination displacement, preventing it from being transmitted to the gear system and causing detection errors.
Solution Approach 2:
The patent changes the mechanical connection parameter from a rigid direct connection to an elastic flexible connection. By introducing the elastic member, the system transitions from a rigid coupling where inclination is directly transmitted to a flexible coupling where the elastic member can deform to absorb inclination effects. This parameter change allows the first gear to rotate accurately relative to the steering shaft even when the shaft itself is inclined.
2Productivity
If the first gear is directly connected to the steering shaft, then the rotation transmission is efficient, but the transmission manner is considerably affected when the steering shaft is inclined, generating detection error
Solution Approach 1:
The elastic member serves as a mediator that maintains efficient rotation transmission while protecting against inclination-induced errors. It allows the first gear to receive rotational motion from the steering shaft efficiently but blocks the transmission of inclination effects, thus maintaining both productivity and reliability under varying operating conditions.
Solution Approach 2:
The elastic member provides beforehand cushioning by being pre-installed in a compressed state between the steering shaft and the first gear. This pre-compression creates a cushioning effect that absorbs inclination displacements before they can affect the gear transmission, preventing detection errors before they occur.
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 detection errors and enhances the accuracy of steering angle measurements by maintaining the first gear's stability and precise rotation transmission, even when the steering shaft is inclined, thereby improving the overall detection precision.
Implementation Method 1
an elastic member (23) compressed in the given annular clearance (t1) between the steering shaft (6) and the first gear (24), a thickness of the elastic member (23) in a non-compressed condition being larger than a thickness of the given annular clearance (t1)
Implementation Method 2
a first MR element (31A) detecting a change of a magnetic field produced by the magnetic member of the second gear (25) for obtaining a first rotation angle of the second gear (25); a second MR element (31B) detecting a change of a magnetic field produced by the magnetic member of the third gear (26) for obtaining a second rotation angle of the third gear (26)
Data Source
AI summary
A steering angle sensor 17 is provided which can minimize a detection error even when a steering shaft 6 is inclined. In an annular clearance t1 defined between the steering shaft 6 and an inner cylindrical wall of a first gear 24, there is compressed an elastic O-ring 23. Due to provision of the elastic O-ring 23, inclination of the steering shaft 6, which tends to occur during handling of a steering wheel 1, is suitably absorbed by the elastic O-ring 23, and thus, generation of detection error caused by inclination of the first gear 24, which would follow the inclination of the steering shaft 6, is suppressed or at least minimized.