Rolling Bearing Encoder Cover Non-Contact Section Design
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Solution Overview
Problem
Conventional rolling bearing units with encoders suffer from deformation issues due to the inward radial force applied to the cover, leading to inaccurate positioning and fluctuations in magnetic flux density, affecting the reliability of rotational speed detection.
Innovation Solution
A non-contact section is formed around the inside end section of the cover, with a smaller outer diameter than the inner diameter of the outer ring, to reduce the inward radial force and prevent strain deformation, ensuring precise positioning and maintaining magnetic flux density reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cover is fitted inside and fastened to the outer ring with an interference fit to protect the encoder, then the encoder is protected from damage, but the flat plate section deforms due to inward radial force
Solution Approach 1:
The cover is segmented into three distinct sections along its axial length: a first section that fits inside the outer ring, a second intermediate section, and a third section that covers the encoder. This segmentation allows the first section to bear the interference fit load while isolating the third section from deformation forces, thereby protecting both encoder protection and positioning precision.
Solution Approach 2:
The second section acts as an intermediary element between the first section (which experiences inward radial force from the interference fit) and the third section (which covers the encoder). This intermediate structure transmits and distributes the mechanical load, preventing direct force transmission to the encoder-covering section and thus maintaining its positioning precision while still providing protection.
2Manufacturing precision
If the cover is made rigid to maintain positioning precision, then the flat plate section position is stable, but the inward radial force causes strain deformation
Solution Approach 1:
By dividing the cover into multiple axial sections, the structure can simultaneously exhibit different mechanical properties in different regions. The first section can be designed to accommodate and distribute the interference fit forces, while the third section maintains rigidity for positioning precision, and the second section provides transitional stability.
Solution Approach 2:
Different sections of the cover are designed with different structural characteristics tailored to their specific functions. The first section has structural features suitable for interference fit accommodation, the second section has features for force distribution and transition, and the third section has features optimized for encoder protection and positioning stability, allowing each local region to have the quality needed for its specific role.
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 effectively suppresses strain deformation and maintains the precision of the flat plate section's position, ensuring reliable rotational speed detection by reducing the inward radial force and maintaining the magnetic flux density.
Implementation Method 1
the inside surface in the axial direction of the encoder being a detected surface on which a magnetic flux alternately changes in the circumferential direction
Data Source
Figure 1
Figure 2~3
Figure 4(A)~4(B)
AI summary
Construction is achieved that is able to prevent strain deformation in the axial direction of a flat plate section 21 of a cover 19a when a cylinder section 20 of the cover 19a, which covers the opening on the inside end in the axial direction of an internal space where an encoder 1 is located, is fitted into and fastened to the inside end section in the axial direction of an outer ring 7. A non-contact section 26a is formed all the way around the inside end section in the axial direction of the cylinder section 20 such that the outer diameter is smaller than the inner diameter of the inside end section in the axial direction of the outer ring, and the dimension L26 in the axial direction is two times or more the thickness dimension t19 of a plate member of the cover 19a. With the cover 19a fitted into the inside end section in the axial direction of the outer ring 7, only the portion of the cylinder section 20 that is nearer the outside in the axial direction than the non-contact section 26a is substantially fitted into the inside end section in the axial direction of the outer ring 7 with an interference fit.