Thrust Bearing Top Foil Fixed Edge Design
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Solution Overview
Problem
In thrust foil bearings, the edge on the trailing side of the top foil piece can easily contact the thrust collar, leading to damage, reduced useful life, and potential seizure due to insufficient bearing clearance under high loads.
Innovation Solution
The design ensures the edge on the trailing side of the top foil piece remains approximately parallel to the thrust collar by adjusting the fixed edge's length and orientation, reducing the difference in movement between the outer and inner edges, and incorporating a thin part near the fixed edge to decrease rigidity and facilitate smooth movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the top foil piece is arranged with an inclination angle to form a wedge-shaped bearing clearance, then the load capability of the bearing is improved, but the edge on the trailing side may contact the thrust collar under high load
Solution Approach 1:
The patent changes the geometric parameters of the top foil piece, specifically making the leading edge longer than the trailing edge. This parameter modification allows the foil to pivot around the fixed leading edge while maintaining an optimal inclination angle, preventing the trailing edge from contacting the thrust collar under high load conditions while preserving load capability
Solution Approach 2:
The patent creates a dynamic system where the top foil piece can pivot and adjust its inclination angle in response to varying loads. By fixing only the leading edge and allowing the trailing edge to remain free, the foil dynamically adapts its position to maintain the wedge-shaped clearance and prevent contact, resolving the contradiction between load capability and reliability
2Adaptability or versatility
If the outer circumferential edge of the top foil piece is longer than the inner circumferential edge, then the foil can accommodate radial movement, but the difference in movement between outer and inner edges causes the trailing edge to contact the thrust collar
Solution Approach 1:
The patent applies asymmetry by making the leading edge of the top foil piece longer than the trailing edge. This asymmetric configuration creates a pivot point at the leading edge that allows controlled movement while preventing the trailing edge from contacting the thrust collar, resolving the contradiction between radial movement accommodation and contact prevention
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 design prevents contact between the top foil piece and the thrust collar, thereby extending the bearing's useful life, reducing the risk of seizure, and improving load capability by maintaining optimal inclination angles and fluid pressure.
Implementation Method 1
when the thrust collar rotates from the large side (the leading side) toward the small side (the trailing side) of the bearing clearance, a lubricating fluid flows into a narrow part of the wedge-shaped bearing clearance, and the load capability of the bearing is obtained
Implementation Method 2
The bearing surface of the thrust foil bearing is formed of a flexible foil (metal thin sheet) in order to accept movement of the rotary shaft (movement in the axial direction of or inclination of the thrust collar) which occurs due to vibration or to impact
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
A thrust bearing (3, 3A, 3B) disposed facing a thrust collar (4) provided on a rotary shaft (1) includes: a top foil (10) disposed facing the thrust collar; a back foil (20) supporting the top foil; and an annular shaped base plate (30) supporting the back foil. The back foil includes back foil pieces (21), and the top foil includes top foil pieces (11). An area on the leading side of a top foil piece in the rotation direction of the rotary shaft is provided with a fixed part (13) fixed to the base plate. A fixed edge (12) positioned on the trailing side of the fixed part in the rotation direction linearly extends such that the separation between a straight line extending in the radial direction of the base plate and the fixed edge positioned on the trailing side of the straight line in the rotation direction gradually increases outward from inside in the radial direction.