Asymmetric Piston Compressor Sealing
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Solution Overview
Problem
Reciprocating piston compressors with a rigid connection between the piston and connecting rod face reduced sealing ability in the middle range of motion during the compression stroke due to piston inclination, leading to inefficiencies and potential leaks, especially when using inexpensive materials and simple production methods.
Innovation Solution
The piston and cylinder are designed with an oval-elliptical shape and a geometrically or material-technically flexible piston seal to compensate for crescent-shaped gaps created by piston inclination, ensuring maximum sealing ability throughout the stroke movement, including the dead centers, through the use of an oval-elliptical piston shape and a compressible ring-shaped seal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a rigid connection between piston and connecting rod is used, then manufacturing complexity is reduced and production costs are lowered, but sealing ability deteriorates in the middle range of motion due to piston inclination
Solution Approach 1:
The piston is designed with an asymmetric inclination angle (α) relative to the connecting rod axis, creating different clearance characteristics at TDC versus BDC. This asymmetric geometry allows the piston to maintain optimal sealing contact with the cylinder wall during the compression stroke while accommodating the rigid connection constraint, thereby resolving the contradiction between manufacturing simplicity and sealing reliability.
Solution Approach 2:
The invention changes the geometric parameters of the piston, specifically introducing an inclination angle α and positioning the piston axis offset from the connecting rod axis. This parameter modification allows the piston to compensate for inclination effects during compression while maintaining a rigid, simple connection, thus improving sealing ability without increasing manufacturing complexity.
2Reliability
If a highly flexible piston seal is used, then sealing ability is improved, but the seal hardens at low temperatures and loses its sealing effectiveness
Solution Approach 1:
Instead of relying on seal material flexibility, the invention changes the geometric parameters of the piston (inclination angle, axis offset) to maintain sealing contact. This approach eliminates the temperature-dependent behavior of flexible seals while achieving reliable sealing through geometric compensation, thereby resolving the contradiction between sealing ability and temperature adaptability.
3Reliability
If the piston axis is aligned with the cylinder axis at dead centers, then sealing ability is maximized, but piston inclination creates crescent-shaped gaps during compression stroke
Solution Approach 1:
The piston is designed with asymmetric inclination and axis offset, creating different geometric relationships at TDC versus BDC. This asymmetric design allows the piston to maintain optimal sealing contact during compression while the clearance characteristics at idle are compensated by the asymmetric geometry, preventing harmful gap formation and resolving the contradiction between sealing ability and gap prevention.
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
This design enhances the compression ratio and delivery volume by up to 20% compared to prior art, maintaining secure sealing during both compression and idle strokes, and allows for efficient operation in portable devices like roadside assistance systems.
Implementation Method 1
a compressible ring-shaped seal... an elastic seal between the piston and the cylinder wall takes place
Data Source
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AI summary
The invention relates to a reciprocating piston compressor having a piston that is driven by way of a slider-crank mechanism and can be moved back and forth in a cylinder and is sealed with respect to the cylinder wall, which is arranged in a fixed manner to the connection rod axis. The piston and/or the cylinder are configured such that the sickle-shaped gaps between piston edge and cylinder wall formed during the compression stroke due to the relative inclination or tilt between piston and cylinder axis can be sealed, and leakages can be offset in this way.