Ball Joint Rotation Sensor for Compact Z-Axis Angle Measurement
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Solution Overview
Problem
Existing ball joints face challenges in accurately measuring the angle of rotation around the Z axis due to complex structures, assembly difficulties, and excessive dimensions, which are critical for applications like self-driving vehicles.
Innovation Solution
A compact ball joint design with integrated angular measurement capabilities, utilizing a pin with a spherical end enclosed by covering elements and a magnetic encoder, allowing for precise rotation control around the Z axis while maintaining simplicity and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an external bearing element is added to allow rotation around the Z axis, then the rotation measurement capability is improved, but the overall dimensions and device complexity increase
Solution Approach 1:
The patent combines the bearing function and rotation measurement function into a single integrated structure. The bearing element with internal cavity houses both the rotational movement mechanism and the angular sensor, eliminating the need for separate external bearing elements and reducing the total number of components while maintaining measurement capability
Solution Approach 2:
The pin with spherical end is nested within the bearing element's internal cavity, which itself is nested within the body. This nested arrangement allows multiple functions (rotation support, rotation restriction, angular measurement) to be compactly integrated without increasing overall dimensions, resolving the contradiction between measurement capability and device complexity
2Measurement precision
If a conical cavity is created in the spherical section for drive shaft insertion, then the rotation measurement function is added, but the spherical section strength is weakened
Solution Approach 1:
The patent extracts the drive shaft function from the spherical section by providing a separate cylindrical cavity in the pin body. This separates the measurement function from the spherical section, allowing the spherical section to maintain its full strength while the pin provides the necessary interface for the drive shaft and angular sensor
Solution Approach 2:
The pin is segmented into distinct functional zones: the spherical end for rotation support, the cylindrical cavity for drive shaft insertion, and the longitudinal cavity for angular sensor placement. This segmentation allows each component to be optimized for its specific function without compromising the strength of the spherical section
3Measurement precision
If tight tolerances are applied to the coupling between joint, drive shaft, and sensor, then the angular measurement accuracy is improved, but the manufacturing difficulty and cost increase
Solution Approach 1:
The pin serves multiple functions simultaneously: it provides the spherical end for rotation support, contains the cylindrical cavity for drive shaft insertion, and houses the longitudinal cavity for the angular sensor. This multi-functionality reduces the number of separate components and their associated coupling interfaces, thereby reducing the cumulative tolerance requirements while maintaining measurement 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 provides accurate and continuous rotation angle measurement around the Z axis, enhancing integration with existing mechanical structures and reducing wear, while maintaining compact dimensions.
Implementation Method 1
a magnetic encoder, allowing for precise rotation control around the Z axis
Data Source
AI summary
A ball joint contains a body and a pin having a first threaded end and a second spherical end which is rotatably arranged within a seat of the body. The pin cooperates with a first spherical-cap-shaped element inserted within a further seat having a corresponding shape of a second spherical-cap-shaped element cooperating with a covering element to close the spherical end of the pin within the body. The second spherical end of the pin and the first and second spherical-cap-shaped elements include pairs of recesses and ridges in the contact areas for reciprocally compenetrating, the pairs of recesses and ridges being arranged at 90° to each other to allow rotation of the pin along all axes in the body. An angular movement sensor integral with the body of the joint cooperates with the second spherical-cap-shaped element to detect rotation of the pin.