Radial-Plane Sensor Arrangement for Roller Bearing Gap Stability
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Solution Overview
Problem
Conventional thin motors experience inaccurate rotation angle position detection due to tilting under moment load, which causes a significant gap change in the resolver, leading to potential misdetection, and increasing preload to mitigate this shortens the roller bearing's lifespan.
Innovation Solution
A roller bearing device with a radial-plane arrangement structure where the rotation sensor and roller bearing are on the same plane, reducing gap changes and allowing for extended bearing life by minimizing the impact of moment loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the rotation sensor is arranged away from the roller bearing to improve detection accuracy, then the gap change increases under moment load, but the detection precision deteriorates
Solution Approach 1:
The patent transitions from axial arrangement to radial-plane arrangement, placing the rotation sensor and roller bearing on the same radial plane rather than along the axial direction. This dimensional change allows the sensor to be positioned closer to the bearing while maintaining stability under moment load, as the radial positioning reduces the lever arm effect that causes gap changes during tilting.
2Reliability
If multiple cross roller bearings are used to increase rigidity and prevent gap change, then the reliability improves, but the device complexity increases
Solution Approach 1:
The patent extracts the rotation sensor from the axial arrangement and positions it on the radial plane, separating its function from the load-bearing axial structure. This allows the single roller bearing to maintain both support and sensing functions without requiring additional bearings solely for rigidity, thereby reducing overall device complexity while maintaining reliability.
3Measurement precision
If preload is increased to fix the inner and outer rings, then the measurement precision improves, but the duration of action of stationary object decreases
Solution Approach 1:
By repositioning the rotation sensor on the radial plane, the patent eliminates the need for excessive axial preload to maintain detection accuracy. The radial positioning inherently reduces gap changes under moment load, allowing the bearing to operate with appropriate preload levels that ensure both precision and extended lifespan.
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 configuration reduces the likelihood of rotation sensor misdetection and extends the life of the roller bearing by minimizing gap changes and avoiding the lifespan shortening effects of increased preload.
Implementation Method 1
a roller bearing having an inner ring and an outer ring; an inner-ring supported member supported by the inner ring; an outer-ring supported member supported by the outer ring
Implementation Method 2
a rotation sensor that is arranged between the inner-ring supported member and the outer-ring supported member and outputs a sensor signal that changes according to relative positions thereof
Data Source
AI summary
Provided is a roller bearing device, which is suitable for preventing misdetection of a rotation sensor when a moment load is applied. A thin motor 100 includes a cross roller bearing 14 having an inner ring 14a and an outer ring 14b, a stator 22 supported by the inner ring 14a, a rotor 12 supported by the outer ring 14b, a motor unit 16 that applies rotation torque to the rotor 12, and a resolver 30 that detects a rotation angle position of the rotor 12. The resolver 30, the cross roller bearing 14, and the motor unit 16 are arranged in the recited order from the radially inner side on a radially identical plane.