Rotational Angle Detection Device Using Overlapping Gears
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Solution Overview
Problem
Conventional rotational angle detection devices have complex structures due to the need for multiple detectors to accurately detect multiple-rotation rotational angles of 360 degrees or more, which complicates their design and functionality.
Innovation Solution
A rotational angle detection device featuring a first gear with overlapping teeth and a second gear with a higher tooth count, where the second gear rotates orthogonally to the first gear, allowing the first gear to rotate 360 degrees or more while the second gear rotates a single 360-degree cycle, simplifying the configuration and enabling detection of multiple rotations with a single second gear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple detectors are used to detect multiple-rotation rotational angles, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The detection function is segmented between two gears: the first gear with fewer teeth handles the multiple-rotation counting, while the second gear with more teeth provides precise angular position detection. This segmentation allows a single detector to effectively perform the work of multiple detectors by utilizing the gear ratio relationship.
Solution Approach 2:
The first gear acts as an intermediary mechanism that converts the rotational motion of the object into a form that can be accurately measured by the second gear and single detector. The gear interaction mediates between the object's rotation and the detection system, enabling precise measurement without requiring multiple detectors.
2Device complexity
If a single second gear is used for detection, then device complexity is reduced, but the ability to detect multiple-rotation angles is limited
Solution Approach 1:
The system combines two gears with different tooth counts (first gear with fewer teeth, second gear with more teeth) to create a composite mechanical detection system. This composite structure leverages the gear ratio to simultaneously achieve multiple-rotation detection capability and precise angular measurement with a single detector.
Solution Approach 2:
The solution adds a mechanical dimension through the gear interaction, where the first gear's rotation is transferred to the second gear through meshing teeth. This mechanical dimension allows the system to detect multiple rotations by counting the rotations of the second gear, which rotates multiple times for each rotation of the first gear.
3Measurement precision
If the tooth count of the second gear is increased, then measurement precision is improved, but manufacturing complexity increases
Solution Approach 1:
The system changes the tooth count parameter of the gears to achieve the desired measurement precision. By selecting appropriate tooth counts for the first and second gears (with the second gear having more teeth), the system achieves high angular resolution while keeping the manufacturing complexity manageable through standard gear manufacturing processes.
Data Source
AI summary
A rotational angle detection device includes a first gear that rotates about a first rotation axis and that has a main surface having an annular shape that crosses the first rotation axis and a plurality of first teeth provided on the main surface; a second gear that rotates about a second rotation axis in engagement with the first gear and that has a larger number of second teeth than the first teeth; and a sensor that detects a rotational angle of the second gear. The second rotation axis extends in a direction orthogonal to both of a virtual line that connects a center of the first gear and a position where the first gear and the second gear are engaged with each other, and the first rotation axis. Each of the first teeth extends so as to shift from an outer side toward an inner side in a radial direction of the main surface as it shifts along a circumferential direction of the main surface. Adjacent two of the first teeth are disposed so as to overlap each other in the radial direction.