Half Bearing Recess Design for Oil Flow Guidance
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Solution Overview
Problem
Conventional half bearings with minute recesses on the sliding surface of crankshafts in internal combustion engines experience turbulence in oil flow, leading to increased friction loss due to reduced oil pressure and premature contact between the shaft and the bearing surface.
Innovation Solution
A half bearing design featuring a semi-cylindrical shape with recesses that have a smooth convex curve and circumferential grooves extending from the recess surface towards the outer diameter, guiding oil flow in the same direction as the shaft rotation to minimize turbulence and maintain oil pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If minute recesses are formed on the sliding surface of the half bearing, then friction loss during sliding is reduced, but turbulence occurs in the oil flow near the recess causing increased friction loss and reduced oil pressure
Solution Approach 1:
The recess is segmented into a central recess portion and a groove portion with multiple circumferential grooves. This segmentation allows the oil flow to be organized into orderly patterns within the grooves, preventing turbulence while maintaining low friction through the recessed structure.
Solution Approach 2:
The recess surface is designed with a convex curved shape rather than a flat or sharp configuration. This curvature promotes smooth oil flow patterns and prevents turbulent eddies from forming, thereby maintaining oil pressure while reducing friction loss.
2Loss of energy
If the sliding surface is made smooth, then friction loss is reduced, but the shaft surface comes into contact with the bearing surface increasing friction loss
Solution Approach 1:
The bearing surface has different local properties: the recess area provides oil retention and pressure maintenance, while the surrounding sliding surface maintains smoothness for low friction. This local differentiation allows the system to achieve both low friction and adequate oil pressure to prevent shaft contact.
Solution Approach 2:
The recess structure pre-establishes oil pressure zones before the shaft contacts the bearing surface. By having the recesses in place beforehand, the oil is positioned to maintain separation between the shaft and bearing, preventing harmful contact.
3Reliability
If circumferential grooves are added to the recess, then oil flow is guided effectively reducing turbulence, but the device complexity increases
Solution Approach 1:
The circumferential grooves are merged into the recess structure as an integrated feature rather than separate components. The grooves form part of the recess itself, creating a unified structure that guides oil flow while maintaining manufacturing simplicity and avoiding additional device complexity.
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 design reduces friction loss by maintaining oil pressure and guiding oil flow effectively, preventing premature contact between the shaft and the bearing surface, thus enhancing the operational efficiency of the crankshaft.
Implementation Method 1
The groove forming zone includes a plurality of circumferential grooves which recess from the recess surface toward the outer diameter side of the half bearing. The circumferential grooves extend from the peripheral edge of the recess along the circumferential direction of the half bearing.
Implementation Method 2
The recess surface is smooth and is recessed from the sliding surface toward an outer diameter side of the half bearing. The recess surface forms a convex curve toward the outer diameter side of the half bearing, in cross-sectional view in a direction parallel to a circumferential direction of the half bearing.
Data Source
Figure 1~2
Figure 3~5
Figure 6~7
AI summary
Provided is a semi-cylindrical shaped half bearing (31, 32; 41, 42). The half bearing has an inner surface forming a sliding surface and including a plurality of recesses (71). Each recess (71) has a smooth recess surface and a peripheral edge. The recess surface forms a convex curve toward the outer diameter side of the half bearing in cross-sectional view in a direction parallel to a circumferential direction of the half bearing. The recess (71) includes a groove forming zone (73) adjacent to the peripheral edge of the recess. The groove forming zone includes a plurality of circumferential grooves (731). The circumferential grooves (731) extend from the peripheral edge of the recess (71) along the circumferential direction of the half bearing. The present invention also provides a cylindrical sliding bearing including the above half bearing.