Steering Wheel Rotation Sensor Using Gear Rack Displacement
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Solution Overview
Problem
Conventional steering wheel rotation angle sensors, particularly those based on Giant Magneto Resistive (GMR) technology, require high precision and numerous components, making them complex and costly to implement effectively.
Innovation Solution
A device comprising a linear motion transforming element, such as a gear and rack system connected to the steering column, which converts steering wheel rotation into linear movement, and a processing element to determine the rotation angle based on the rack's distance and direction of movement relative to an engagement origin, utilizing various sensing units like elastic elements, pressure sensors, or capacitive grating displacement sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GMR-based direction sensor is used for measuring steering wheel rotation, then measurement precision is improved, but device complexity increases due to many components and high precision requirements for the gear
Solution Approach 1:
The patent replaces the complex GMR-based magnetic sensing system with a mechanical rack displacement sensing system. The gear rack's linear displacement is directly measured using simple mechanical sensors (potentiometer, LVDT, or optical encoder), eliminating the need for complex magnetic sensors and their associated signal processing circuits while maintaining measurement accuracy.
Solution Approach 2:
The patent extracts only the essential measurement function from the complex GMR sensor system. By using a simple gear rack mechanism connected to the steering shaft, it isolates the core measurement task (converting rotational motion to linear displacement) and measures it directly, removing unnecessary magnetic field detection components and complex signal processing requirements.
2Measurement precision
If GMR-based direction sensor with many components is used, then measurement precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent employs inexpensive mechanical sensing components (potentiometers, LVDTs, or optical encoders) to replace expensive GMR sensors and their supporting infrastructure. These simple mechanical sensors are cost-effective, easily manufactured, and require minimal calibration, significantly reducing overall system manufacturing costs while maintaining adequate measurement precision for steering angle detection.
Solution Approach 2:
The substitution of complex magnetic sensing technology with simple mechanical displacement sensing reduces manufacturing costs. The mechanical rack and sensor assembly can be produced using conventional manufacturing processes, avoiding the need for specialized magnetic material processing and complex electronic circuit fabrication required by GMR sensors.
3Measurement precision
If high precision gear is used in GMR-based sensor, then measurement precision is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent uses a gear rack with standard, easily manufactured tooth profiles rather than high-precision gears. The rack only needs to convert rotational motion to linear displacement adequately, not with extreme precision. The measurement is achieved by directly sensing the rack's linear position, which tolerates greater manufacturing variations in the rack teeth compared to the precise rotational encoding required by GMR sensors.
Solution Approach 2:
By replacing the precision gear mechanism with a simple gear rack and direct linear displacement sensor, the patent eliminates the need for high-precision gear manufacturing. The rack can be produced using standard machining processes, and the measurement accuracy depends on the linear sensor's precision rather than the rack's tooth precision, significantly easing manufacturing requirements.
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 solution simplifies the structure, reduces component complexity, and lowers costs while maintaining high precision, offering an efficient method for determining steering wheel rotation information compared to traditional GMR-based sensors.
Implementation Method 1
an elastic element whose elastic end is connected to the rack in a manner of expanding and contracting with the movement of the rack
Implementation Method 2
a pressure sensor which is combined with the elastic element in a manner of being able to sense an elastic force of the elastic element
Implementation Method 3
a gear connected to the steering column; a rack engaged with the gear, wherein the steering column is driven to rotate by the steering wheel to make the gear connected to said steering column rotate, and rotation of the gear drives the rack engaged therewith to move relative to an engagement origin along a rack length direction
Data Source
AI summary
A device for determining steering wheel rotation information, which comprises a linear motion transforming element connected to a steering column of a steering wheel for transforming rotation of the steering wheel into a linear movement, and a processing element electrically connected to the linear motion transforming element for determining steering wheel rotation information based on the linear movement transformed by the motion transforming element.