Piston Groove Geometry for Oil Wiper Ring Guidance
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Solution Overview
Problem
Existing piston designs for internal combustion engines face challenges in effectively wiping off oil from the shaft walls and ensuring optimal guidance and discharge of oil, particularly due to the reduced support surface and impaired lubrication caused by the smaller upper edge diameter of the oil wiper ring recess.
Innovation Solution
A piston design featuring a groove for the oil wiper ring with a larger lower flank diameter than the recess, along with a recess configured as a cylindrical blind hole or through-bore intersecting the groove, ensures efficient oil discharge and guidance by maintaining a larger support surface and preventing oil flow into the piston.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the upper edge of the recess has a smaller diameter than the lower edge (conventional design), then oil can be wiped off more effectively from the shaft walls, but the support surface for the oil wiper ring is reduced and guidance is worsened
Solution Approach 1:
The recess is designed with different diameters at its upper and lower edges, creating local quality variations. The lower edge has a larger diameter than the upper edge, providing enhanced support surface for the oil wiper ring at the critical guidance area while maintaining effective oil wiping capability at the shaft wall interface.
2Reliability
If the lower edge of the groove has a larger diameter than the recess (invention), then good guidance of the oil wiper ring is ensured, but the complexity of production increases
Solution Approach 1:
The invention changes the geometric parameters of the recess by specifying that the lower edge diameter is larger than the upper edge diameter by at least 0.08 mm. This parameter modification optimizes the support surface for the oil wiper ring, ensuring reliable guidance without significantly complicating the manufacturing process.
3Productivity
If a continuous bore is provided to the inside of the piston, then oil discharge is enhanced, but oil flows from the inside to the outside increasing oil consumption
Solution Approach 1:
The invention extracts or removes the harmful continuous bore connection to the piston interior. Instead, a blind hole configuration is used that terminates before reaching the piston inside, thereby preventing oil from flowing into the piston and subsequently leaking to the outside, while still maintaining effective oil discharge from the groove area.
4Productivity
If the bore extends deep to the bottom of the groove, then free flow cross-section for oil discharge is ensured, but the risk of oil flowing into the piston increases
Solution Approach 1:
The bore is designed to extend partially deep toward the groove bottom, providing sufficient flow cross-section for effective oil discharge, but deliberately stops before reaching the piston interior. This partial depth is optimal - deep enough to ensure free oil flow from the groove, but not so deep as to create a direct pathway for oil to enter the piston.
Data Source
AI summary
A piston (10) for an internal combustion engine includes a groove (16) for an oil wiper ring and a recess (18) between the groove (16) and at least one shaft wall (20). A lower edge of the groove (16), which is closer to the shaft wall (20), has a larger diameter than a lower edge of the recess (18).