Floating Bush Bearing Geometry to Suppress Reverse Oil Flow
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Solution Overview
Problem
The existing floating bush bearing experiences a decrease in lubricant oil supply at high rotational shaft speeds, leading to potential seizure and damage due to eccentric forces and reverse oil flow along the oblique surfaces.
Innovation Solution
The floating bush bearing incorporates an oblique surface with a protruding portion and varying obliquity angles to suppress reverse oil flow, increasing oil supply and reducing rotational drag, featuring a cylindrical shape with an insertion hole, inner and outer peripheral surfaces, and axial end surfaces with vertical and oblique components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the rotational shaft rotates at high speed, then the power output increases, but the eccentric force acting on the floating bush body part increases causing lubricant oil supply to decrease
Solution Approach 1:
The invention introduces a protruding portion at a specific location on the oblique surface of the floating bush body part. This local structural modification creates a preferential flow path that directs lubricant oil toward the gap between the inner peripheral surface and rotational shaft, ensuring reliable lubrication even at high rotational speeds where eccentric forces are significant.
2Quantity of substance
If lubricant oil is introduced from the outer side in the axial direction, then the oil supply path is established, but the high pressure at the radially inner side causes oil to flow backward toward the outer side in the axial direction
Solution Approach 1:
The protruding portion on the oblique surface acts in advance to counteract the harmful reverse flow effect. By creating a flow separation and directing the lubricant oil along a preferred path toward the inner peripheral surface, the protruding portion prevents the oil from flowing backward along the axial direction, thus eliminating the harmful effect before it can occur.
3Ease of manufacture
If the oblique surface is made linear to simplify manufacturing, then the manufacturing ease increases, but the lubricant oil flow becomes unstable causing insufficiency in oil supply
Solution Approach 1:
Instead of making the entire oblique surface complex, the invention applies a localized protruding portion at a specific position on the oblique surface. This local modification is relatively easy to manufacture while effectively controlling the lubricant oil flow pattern, directing it toward the gap between the inner peripheral surface and rotational shaft to ensure stable and sufficient oil supply.
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 enhances lubricant oil supply to the gap between the bush and shaft, preventing seizure and damage while reducing rotational loss by effectively managing oil flow and pressure differences.
Implementation Method 1
The floating bush bearing is configured to support the rotational shaft rotatably via a liquid film formed by a lubricant oil filling the gap between the floating bush body part and the rotational shaft.
Implementation Method 2
A lubricant oil is introduced, via the above oil supply hole, to the gap between the floating bush body part and the rotational shaft, from the outer side in the radial direction.
Implementation Method 3
the lubricant oil positioned between the linear oblique surface of the floating bush body part and the outer peripheral surface of the rotational shaft has a higher pressure at the radially inner side than at the radially outer side, which generates a flow that flows toward the outer side in the radial direction
Data Source
AI summary
A floating bush bearing configured to support a rotational shaft rotatably includes: a floating bush body part formed to have a cylindrical shape having an insertion hole through which the rotational shaft is inserted. The floating bush body part includes: an inner peripheral surface; an outer peripheral surface having a greater width dimension than the inner peripheral surface in an axial direction of the floating bush body part; and an axial end surface which connects an end of the inner peripheral surface and an end of the outer peripheral surface, the axial end surface including a vertical surface extending along a direction orthogonal to the axial direction from the end of the outer peripheral surface toward a radially inner side and an oblique surface extending from a radially inner end of the vertical surface toward the end of the inner peripheral surface. The oblique surface has a protruding portion protruding from a virtual line which linearly connects the radially inner end of the vertical surface and the end of the inner peripheral surface.