Steering Actuator Magnetic Sensing for Lower-Complexity SBW
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Solution Overview
Problem
Existing Steer By Wire (SBW) systems face challenges with increased sensor costs and reduced mass production due to the use of linear variable differential transformer (LVDT) sensors, and high assembly costs due to the complex pinion and rack bar structure.
Innovation Solution
A steering actuator apparatus with a simplified coupling structure that includes a housing, a driving unit, a transmission shaft, a measurement unit, and rotation prevention units, which integrates a pinion made of spur gear and manufactured by insert injection, reducing assembly complexity and costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If LVDT sensors are used to detect rack bar position, then steering angle measurement is achieved, but sensor size increases and unit price increases
Solution Approach 1:
The patent replaces the LVDT sensor (a complex mechanical/electrical sensing device) with a simpler magnetic field-based detection system using a magnet attached to the rack bar and a magnetic sensor on the pinion. This substitution eliminates the need for the complex LVDT structure while achieving the same steering angle measurement function, thereby reducing sensor size and unit price.
2Strength
If heat treatment is applied to pinion and rack bar, then structural strength is improved, but manufacturing cost increases excessively
Solution Approach 1:
The patent employs composite material construction for the pinion and rack bar, combining different materials with complementary properties to achieve the required structural strength without heat treatment. This approach allows cost-effective manufacturing while maintaining the necessary mechanical properties for reliable operation.
3Manufacturing precision
If clearance compensation structure is added to pinion assembly, then assembly precision is improved, but the number of assembly parts increases
Solution Approach 1:
The patent integrates the clearance compensation function directly into the pinion assembly structure itself, merging multiple functions into a single component design. This eliminates the need for separate clearance compensation parts, reducing the total number of assembly parts while maintaining the required assembly precision.
4Stability of the object's composition
If rack bar is supported in housing, then positional stability is achieved, but rotational movement may occur within housing
Solution Approach 1:
The patent introduces a rotation prevention mechanism as an intermediary element between the rack bar and housing. This intermediary structure specifically addresses rotational movement while maintaining the positional stability provided by the housing support, thereby improving overall system reliability without compromising positional accuracy.
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 stabilizes the rack bar support, optimizes packaging, reduces manufacturing costs, and prevents rotational movement within the housing, enhancing the SBW system's efficiency and cost-effectiveness.
Implementation Method 1
The transmission shaft may include a ball screw configured to convert the driving force generated from the driving unit into a straight line motion
Data Source
AI summary
A steering actuator apparatus for a vehicle may include: a housing, a driving unit configured to be supported by the housing and generates a driving force, a transmission shaft, which is installed inside the housing to be movable, moves back and forth by receiving the driving force from the driving unit, and varies a steering angle of a wheel, a measurement unit configured to measure the steering angle of the wheel in conjunction with a movement of the transmission shaft, a first rotation prevention unit provided between the housing and the transmission shaft and fixed to the transmission shaft and a second rotation prevention unit, which is detachably coupled to an outside of the housing and interferes with the first rotation prevention unit to prevent relative rotation of the housing and the transmission shaft.