Combined Sensor Bearing Assembly Linear Range Detection
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Solution Overview
Problem
Existing combined sensor and bearing assemblies face challenges in compact design due to the need for extra signal processing circuits for rotation angle detection, and magnetization techniques for sinusoidal waveform representation are unstable, leading to precision issues and mechanical friction problems.
Innovation Solution
A combined sensor and bearing assembly with a rolling bearing unit, a magnetized ring-shaped to-be-detected member, and a magnetic detector of analog output type, where only the linear range of magnetic characteristic is used for rotation angle detection, allowing for precise detection within a limited range and simplifying assembly, and a method of magnetizing using a magnetizing yoke assembly with curved end faces to achieve sinusoidal magnetic intensity distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two 90° phase offset sinusoidal outputs are used for rotation detection, then the absolute position of rotation angle can be detected, but an extra signal processing circuit is required which increases device complexity and size
Solution Approach 1:
The patent extracts and utilizes only the linear range portion of the sinusoidal magnetic characteristic for rotation detection. By taking out this specific linear portion and using it as the detection basis, the system achieves absolute position detection without requiring complex signal processing circuits to handle the full sinusoidal waveform, thus reducing device complexity while maintaining measurement precision.
Solution Approach 2:
The patent changes the parameter of magnetic characteristic utilization from the full sinusoidal waveform to only its linear range portion. This parameter change allows the system to achieve sufficient detection precision for limited rotation ranges without the need for additional signal processing circuits that would be required to process complete sinusoidal outputs.
2Ease of manufacture
If air-core coil magnetization is used for the magnet, then the magnetization process is simple, but the magnetic field lacks stability leading to precision issues
Solution Approach 1:
The patent introduces a magnetizing yoke assembly as an intermediary device between the magnetization source and the magnet. This yoke assembly with curved end faces serves as a mediator that shapes and stabilizes the magnetic field during the magnetization process, ensuring both ease of manufacture and magnetic field stability for achieving precise sinusoidal magnetic characteristics.
3Ease of operation
If the magnet and detector are mounted without precise alignment, then assembly is easier, but the gap between them varies causing detection output instability
Solution Approach 1:
The patent employs curved surfaces, specifically the curved end faces of the magnetizing yoke assembly, to ensure uniform magnetic field distribution and consistent gap maintenance between the magnet and detector. This curvature-based approach allows for easier assembly while maintaining detection output stability by naturally accommodating minor alignment variations.
4Volume of moving object
If a limited rotation range is used for detection, then the assembly can be more compact, but the detection capability is restricted to a certain angle range
Solution Approach 1:
The patent applies local quality by focusing the magnetic characteristic utilization on the specific linear range portion that corresponds to the required rotation detection range. This localized approach allows the assembly to be optimized for compact size while maintaining accurate detection within the specific angle range needed for the application.
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
Enables precise detection of absolute rotation position within a limited angle range, stabilizes detection output, and simplifies assembly by eliminating the need for additional signal processing and ensuring uniform gap size between the magnet and detector, while reducing mechanical friction.
Implementation Method 1
magnetizing the to-be-detected member (7) with a magnetizing yoke assembly (17) having a pair of yoke arms (18b) with curved end faces (18ba)
Implementation Method 2
a magnetic detector (8) including a magnetic sensor of an analog output type disposed in face-to-face relation with the to-be-detected member (7)
Data Source
AI summary
A combined sensor and bearing assembly (1) of the present invention includes a rolling bearing unit (22) and a rotation sensor unit (23). The rolling bearing unit (22) includes a rotatable raceway member (2), a stationary raceway member (3) mounted around the rotatable raceway member (2) with an annular bearing space defined between it and the rotatable raceway member (2), and a circular row of rolling elements (4). The combined sensor and bearing assembly (1) also includes a to-be-detected member (7) including a magnet secured to the rotatable raceway member (2), and a magnetic detector (8) including a magnetic sensor of an analog output type disposed in face-to-face relation with the to-be-detected member (7). Only a range in which a magnetic characteristic of the to-be-detected member (7) relative to the magnetic detector (8) exhibits linearity is used for detection of rotation angle of the rotatable raceway member (2).