Half Thrust Bearing Recesses for Oil Retention
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Solution Overview
Problem
The reduction in lubrication oil supply due to downsized oil pumps in internal combustion engines leads to increased friction and vibration in crankshafts, causing seizure issues in half thrust bearings, especially near the circumferential center portion, where the thrust collar directly contacts the sliding surface.
Innovation Solution
A semi-annular-shaped half thrust bearing with a sliding surface featuring a plurality of recesses and grooves, where the recesses are convex towards the back surface and the grooves extend along the center line direction, providing enhanced oil retention and pressure distribution to prevent seizure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the oil pump is downsized to improve fuel economy, then the amount of lubrication oil supplied to the bearings is reduced, but the retainability of lubrication oil on the sliding surface deteriorates
Solution Approach 1:
The sliding surface is formed with multiple recesses that have convex curved surfaces, creating a porous-like structure that captures and retains lubrication oil. The grooves within each recess further enhance oil retention by providing additional storage spaces. This allows the bearing to maintain adequate lubrication even when the overall oil supply from the downsized pump is reduced.
Solution Approach 2:
The invention transitions from a flat sliding surface to a three-dimensional structure with recesses having convex curved surfaces and internal grooves. This dimensional change creates multiple oil storage zones and flow paths, significantly increasing the oil retention capacity without adding external components or increasing the pump size.
2Weight of moving object
If the crankshaft shaft diameter is reduced to reduce engine weight, then the rigidity of the crankshaft deteriorates, but the amount of material and complexity are reduced
Solution Approach 1:
The invention applies local quality enhancement by creating recesses with convex curved surfaces at specific locations on the sliding surface. These localized structural modifications provide enhanced oil retention and pressure distribution precisely where needed to compensate for the reduced overall rigidity of the thinner crankshaft, without increasing the overall shaft diameter.
3Weight of moving object
If the crankshaft has lower rigidity due to reduced shaft diameter, then deflection and vibration of the crankshaft increase, but the weight reduction is achieved
Solution Approach 1:
The invention converts the harmful effect of increased vibration and deflection into a beneficial outcome. The recesses with convex curved surfaces are strategically positioned to provide enhanced oil retention and pressure distribution precisely in the regions where the crankshaft experiences maximum stress and vibration. This compensates for the reduced rigidity by ensuring adequate lubrication under dynamic loading conditions, preventing seizure despite the increased vibration.
4Ease of manufacture
If conventional groove configurations are used on the sliding surface, then manufacturing is simpler, but seizure prevention is insufficient when crankshaft deflection occurs
Solution Approach 1:
The invention employs convex curved surfaces for the recesses instead of flat or simple linear grooves. This curvature is specifically designed to enhance oil retention by creating capillary action and pressure zones that keep lubrication oil in contact with the sliding surface during crankshaft rotation and vibration. The curved geometry provides better seizure prevention while remaining manufacturable using conventional machining processes.
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 described configuration effectively reduces the likelihood of seizure by maintaining high oil pressure and guiding oil flow towards the center line direction, ensuring adequate lubrication even during crankshaft deflection and vibration, thus preventing direct contact and damage.
Implementation Method 1
The recess surface is convex toward the back surface in a cross-sectional view in a direction along a center line of the half thrust bearing. The recess surface includes a plurality of grooves along a center line.
Implementation Method 2
The described configuration effectively reduces the likelihood of seizure by maintaining high oil pressure and guiding oil flow towards the center line direction
Implementation Method 3
The grooves extend along the center line direction V of the half thrust bearing so that smooth surfaces and the grooves are alternately arranged on the recess surface in a horizontal direction H of the half thrust bearing.
Data Source
AI summary
Provided is a semi-annular shaped half thrust bearing. The half thrust bearing has a sliding surface and a back surface opposite to the sliding surface. The sliding surface includes a plurality of recesses. Each recess has a recess surface recessed from the sliding surface toward the back surface. The recess surface is convex toward the back surface in cross-sectional view in a center line direction of the half thrust bearing. The recess surface includes a plurality of grooves. The grooves are recessed from the recess surface toward the back surface. The grooves extend in the center line direction so that smooth surfaces and the grooves are alternately arranged on the recess surface in a horizontal direction of the half thrust bearing.