Radial Foil Bearing Back Foil Retention Without Welding
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Solution Overview
Problem
In radial foil bearings, the back foil may come off from the housing due to weak pressing force before the rotary shaft is inserted, affecting the load capacity and dynamic characteristics of the bearing.
Innovation Solution
A radial foil bearing design featuring an engagement member with a first part overlapping the back foil and a second part attached to the bearing housing, including an engagement groove and claw portions to securely engage the back foil, along with a preload mechanism to ensure the back foil remains attached.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If welding (spot welding) is used to attach the back foil to the housing, then the back foil is secured to the housing, but the back foil or the housing may deform and distortion may occur in the top foil
Solution Approach 1:
The patent replaces the welding (thermal/mechanical) system with a mechanical engagement system consisting of engagement protrusions and engagement notches. The back foil has engagement notches at its side peripheral edge portions, and the housing has engagement protrusions on both side end portions of the inner peripheral surface. This mechanical interlocking provides secure attachment without the deformation and distortion problems caused by welding.
2Reliability
If engagement protrusions and engagement notches are used to prevent the back foil from coming off, then the back foil is secured, but before the rotary shaft is inserted the pressing force is weak and the engagement notch may come off from the engagement protrusion
Solution Approach 1:
The patent implements preliminary action by providing engagement protrusions and engagement notches that are designed to be securely engaged even before the rotary shaft is inserted. The engagement structure is configured so that the engagement notches fit onto the engagement protrusions in advance, creating a pre-engaged state that prevents the back foil from coming off during the insertion process or before operational pressing forces are applied.
3Reliability
If the back foil is secured with engagement structures, then the back foil remains attached to the housing, but the complexity of the housing and back foil structures increases
Solution Approach 1:
The patent applies segmentation by dividing the attachment function into distinct components: engagement protrusions on the housing and engagement notches on the back foil. This segmentation allows each component to have a simple, focused geometry optimized for its specific function, rather than requiring a complex integrated attachment mechanism. The modular nature of the engagement structures simplifies manufacturing and assembly.
Data Source
AI summary
A radial foil bearing includes a bearing housing which has an insertion hole through which a shaft is inserted, a back foil which is disposed on an inner peripheral surface of the insertion hole, and an engagement member which includes a first part and a second part, the first part being disposed to overlap the back foil in a radial direction of the insertion hole and engaged with the back foil, and the second part being attached to the bearing housing, in which the first part has an engagement groove which extends to an end edge of the first part in an axial direction of the insertion hole, and the back foil is disposed in the engagement groove.