Inward-Biased Piston Ring Assembly for Engine Sealing
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Solution Overview
Problem
Internal combustion engines face challenges in maintaining a stable seal between the piston and cylinder wall, particularly at the bottom dead center position, where traditional piston rings may compromise the skirt length and be susceptible to blow-by due to their radial outward bias.
Innovation Solution
A piston ring assembly with a plurality of stacked rings and a circumferentially surrounding spring that biases the rings radially inward, creating a stationary seal within a channel in the cylinder wall, maintaining a gas and fluid tight seal without compromising the skirt length and resisting blow-by.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional piston rings are used with radial outward bias, then sealing force is provided, but the skirt length is compromised and blow-by susceptibility increases
Solution Approach 1:
The patent inverts the conventional bias direction of piston rings from radially outward to radially inward. The spring mechanism applies force in the opposite direction of traditional designs, pushing rings inward against the piston skirt rather than outward against the cylinder wall. This inversion resolves the contradiction by maintaining sealing effectiveness while allowing the skirt to extend longer into the crankcase, eliminating blow-by susceptibility.
Solution Approach 2:
The patent employs a dynamic spring-based biasing mechanism that adapts to varying operating conditions. The spring force dynamically adjusts the radial position of the piston rings based on combustion pressure and engine operation, allowing the rings to maintain optimal sealing contact while accommodating the extended skirt length without compromising sealing reliability.
2Reliability
If piston rings are positioned to seal against cylinder wall, then sealing is provided, but stability during reciprocation is reduced
Solution Approach 1:
The patent introduces a stationary sealing element positioned in a channel within the cylinder wall as an intermediary between the piston and cylinder. This mediator provides the sealing function without requiring traditional piston rings that move with the piston, thereby maintaining piston stability during reciprocation while still achieving effective sealing through the stationary element's interaction with the piston skirt.
3Stability of the object's composition
If skirt length is extended for stability, then piston stability improves, but sealing at bottom dead center is compromised
Solution Approach 1:
By inverting the bias direction to radially inward, the patent ensures that the sealing force is maintained even when the skirt extends longer. The inward-biased rings press against the piston skirt with sufficient force during bottom dead center position, preventing blow-by while accommodating the extended skirt length required for optimal piston stability.
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 solution provides increased stability and effective sealing throughout the piston's range of travel, preventing oil and gas leakage while allowing the skirt to extend into the crank case at the bottom dead center position, enhancing engine performance.
Implementation Method 1
The piston ring assembly also includes a spring which substantially circumferentially surrounds the stacked rings and abuts the outer faces of the rings. The spring biases the stacked rings in a radially inward direction for sealing the inner faces of the rings against the piston body.
Data Source
AI summary
A piston ring assembly for sealing a cylinder wall to a piston body is provided. The piston ring assembly includes a plurality of rings stacked in an axial direction one in abutment with another. Each ring has an inner face and an outer face. The piston ring assembly also includes a spring which substantially circumferentially surrounds the stacked rings and abuts the outer faces of the rings. The spring biases the stacked rings in a radially inward direction for sealing the inner faces of the rings against the piston body. The spring may be of a strip of material bent into a serpentine pattern when in an at rest condition to apply the biasing force against the piston body.