Ball Nut Absolute Position Sensing Without Complex Steering Gears
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Solution Overview
Problem
Existing vehicle steering systems face challenges in accurately determining the absolute position of the steering system without relying on complex gear mechanisms and sensors, particularly in systems without an input/pinion shaft.
Innovation Solution
The implementation of an absolute position sensor system that includes a first gear with a plurality of teeth, a rotational position sensor, and a second gear with a spiral tooth, which is engaged with the first gear to detect the rotational position and accurately determine the absolute position of the ball nut and rack in the steering system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex gear mechanisms and sensors are used to determine absolute position, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts the absolute position sensing function from complex external gear mechanisms and integrates it directly into the ball nut structure. The spiral groove on the ball nut surface serves as the encoding track, eliminating the need for separate gear wheels and sensors, thereby reducing device complexity while maintaining measurement precision.
Solution Approach 2:
The ball nut structure is given multiple functions: it provides mechanical support for the ballscrew, guides the recirculating balls, and simultaneously serves as the encoding element for absolute position sensing through its spiral groove. This multi-functionality eliminates the need for dedicated sensing components, reducing overall system complexity.
2Measurement precision
If additional gears are added to the sensor system, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent merges the ballscrew nut with the encoder disk by forming the spiral groove directly on the ball nut surface. The read head reads positions directly from this integrated structure, eliminating the need for additional gear wheels that would otherwise be required to transfer motion from the ball nut to the sensor.
Solution Approach 2:
The patent replaces complex mechanical gear transmission systems with a direct optical or magnetic reading system. The read head directly reads the spiral groove pattern on the ball nut, substituting mechanical gear intermediaries with a direct sensing mechanism that reduces component count while maintaining 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
This solution allows for precise detection of the absolute position of the steering system, enabling accurate steering control and eliminating the need for additional gears, thus simplifying the system architecture and enhancing its reliability.
Implementation Method 1
a rotational position sensor operatively coupled to the first gear to be configured to detect a rotational position of the first gear
Data Source
AI summary
An absolute position sensor includes a first gear having a plurality of teeth, a rotational position sensor operatively coupled to the first gear to be configured to detect a rotational position of the first gear, and a second gear including a spiral tooth engaged with the plurality of teeth of the first gear to rotate with the first gear, and having a first end with a first distance from a center of the second gear, and an opposite second end with a second distance from the center of the second gear, the second distance being less than the first distance.