Asymmetric Piston Ring Opening for Blowby and Oil Control
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Solution Overview
Problem
Existing piston rings with V-shaped openings face issues with inconsistent sizing leading to excessive friction, blowby quantity, and engine oil consumption, as they require precise matching with cylinder liners, and any mismatch results in reduced sealing effectiveness.
Innovation Solution
A piston ring with a trapezoidal opening design featuring varying thicknesses on either side of the opening, with a trapezoidal boss and groove configuration, allowing for a single-side seal that reduces blowby and oil consumption by ensuring consistent contact with the ring groove.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a V-shaped opening is used in the piston ring, then the sealing effect is improved when sizes match perfectly, but any size mismatch causes excessive blowby quantity and reduced sealing effectiveness
Solution Approach 1:
The piston ring employs an asymmetric trapezoidal opening design where the two sides of the opening have different thicknesses. The thicker side provides a larger sealing surface area that can accommodate size variations and maintain effective sealing, while the thinner side allows for proper fit within the cylinder liner. This asymmetric configuration resolves the contradiction by making the sealing performance less sensitive to size mismatches compared to a symmetric V-shaped design.
2Reliability
If the piston ring size is increased to reduce blowby, then the sealing capability is improved, but the friction with the cylinder liner becomes excessive
Solution Approach 1:
The piston ring features non-uniform thickness distribution around its circumference, with the opening area having varying thickness (thicker on one side, thinner on the other). This local quality variation allows the ring to provide adequate sealing pressure where needed while reducing contact pressure and friction in other areas, thus resolving the contradiction between sealing capability and friction.
3Force
If the piston ring size is decreased to reduce friction, then the friction with the cylinder liner is reduced, but the opening becomes excessively large causing excessive blowby quantity
Solution Approach 1:
By implementing varying thickness at the opening with the thicker side providing enhanced sealing surface area, the design maintains adequate sealing capability even when the overall ring size is reduced to minimize friction. The local thickness variation compensates for the reduced overall size, ensuring the opening does not become excessively large.
4Device complexity
If a closed-end design with vertical closed channel is used, then the structural simplicity is maintained, but gas and engine oil can easily pass through causing high blowby quantity
Solution Approach 1:
The trapezoidal opening with asymmetric thickness distribution creates an uneven sealing geometry that effectively blocks the passage of gas and engine oil. The thicker side of the opening provides a longer sealing path that prevents blowby, while maintaining the relatively simple closed-end structure without requiring complex additional components.
Data Source
AI summary
A piston ring includes a piston ring main body with an opening, at least one trapezoidal boss disposed at one end of the opening on the piston ring main body, and at least one groove disposed at other end of the opening on the piston ring main body, the groove being shaped to correspond with the trapezoidal boss. A height of the trapezoidal boss is not greater than a depth of the groove. The piston ring main body has a width on one side of the opening that is different from a width on the opposite side of the opening, such that during engine operation, only one side surface of the trapezoidal boss contacts a corresponding side surface of the groove.