Piston Sealing Device with Floating Cup and Pressure-Actuated Skirt
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Solution Overview
Problem
Existing piston sealing technologies face challenges in achieving a robust and durable seal under high pressure while minimizing friction losses and maintaining mechanical efficiency, especially in high-pressure oil pumps, where leakage and material stress issues are prevalent.
Innovation Solution
The piston sealing device incorporates a sliding skirt with a pressure transmission channel, an extendable continuous segment, and a sliding skirt spring to maintain a seal with low friction, using a mandrel and elastic washer for mechanical connection and centering rings to manage pressure and leakage, ensuring effective sealing across varying pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a small clearance is provided between the piston and cylinder to achieve sealing, then sealing effectiveness is improved at low pressure, but under very high pressure the cylinder diameter increases causing the clearance to increase significantly and leading to high oil leakage rates
Solution Approach 1:
The patent employs a floating cup piston body that can dynamically adjust its position and deformation under pressure. The cup-shaped piston body deforms elastically under high pressure to maintain constant contact with the cylinder wall, adapting to the changing clearance conditions rather than relying on a fixed small clearance that becomes ineffective under pressure.
Solution Approach 2:
The invention changes the operational parameters of the piston by allowing it to deform under pressure. The floating cup structure transitions from a rigid fixed clearance design to a flexible design where the piston body's shape and position change with pressure, maintaining sealing effectiveness across the full pressure range.
2Reliability
If a seal is provided in a groove on the piston periphery to achieve sealing, then sealing is achieved, but under very high pressure the seal deforms in its groove, exerts strong pressure on the cylinder, and generates high friction losses
Solution Approach 1:
Instead of a static seal in a groove that deforms under pressure, the patent uses a dynamic floating cup piston that moves and deforms elastically. This eliminates the need for a groove-mounted seal and reduces friction by allowing the piston to adapt its position rather than forcing a rigid seal against the cylinder wall.
Solution Approach 2:
The floating cup piston body acts as a flexible structure that can deform under pressure to maintain sealing. This flexible shell approach replaces the rigid groove-mounted seal, allowing the piston to conform to the cylinder wall while reducing contact pressure and friction losses.
3Manufacturing precision
If the piston body is made rigid to maintain small clearance under pressure, then clearance is maintained, but this leads to excessive stresses in the material of both the piston and cylinder
Solution Approach 1:
The patent replaces the rigid piston structure with a dynamic floating cup design that can deform under pressure. This eliminates the need for excessive material strength to maintain rigidity, as the flexible cup naturally adapts to pressure conditions while maintaining effective clearance control through elastic deformation.
Solution Approach 2:
The invention changes the mechanical properties of the piston from rigid to flexible. By allowing the piston body to deform elastically under pressure, the system maintains effective clearance control without requiring high-strength materials that would be needed for a rigid structure under the same conditions.
4Reliability
If cut segments are used for piston sealing, then sealing is provided, but the flow rates of oil leakage at the cut are excessive and the pressure exerted by the segment on the cylinder wall increases friction losses
Solution Approach 1:
The patent divides the piston sealing function into multiple segments or zones along the floating cup piston body. This segmentation allows different portions of the piston to handle different pressure conditions, with the ability to maintain sealing effectiveness while reducing leakage compared to a single cut segment design.
Solution Approach 2:
The floating cup piston segments can dynamically adjust their position and contact pressure under varying pressure conditions. This dynamic behavior reduces leakage flow rates by maintaining optimal sealing contact without the excessive pressure exertion that characterizes rigid cut segment designs.
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 solution provides a robust and durable seal with low to moderate friction losses, even at pressures up to 2000 bars, maintaining mechanical efficiency and reducing material stress, while being cost-effective and applicable to various piston types and machines.
Implementation Method 1
At least one sliding skirt spring which tends to bring the sliding skirt closer to the fixed skirt, and to compress the continuous stretchable segment axially
Implementation Method 2
At least one pressure transmission channel arranged inside the sliding skirt and crossing the latter right through in the axial direction
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The sealing device (1) for a piston (2) the fixed skirt (5) of which moves in a cylinder (8), comprises a sliding skirt (6) through which there passes axially a pressure-transmitting duct (10) and which is connected to the fixed skirt (5) by an inter-skirt mechanical connection (7) while an extendable continuous piston ring (9) is interposed in a sealed manner between said skirts (5, 6) and can come into contact with the cylinder (8) when the piston-ring internal cylindrical face (12) thereof is subjected to the pressure of a fluid (36) via the pressure-transmitting duct (10), a sliding-skirt spring (16) tending to bring said skirts (5, 6) together and to compress the extendable continuous piston ring (9) axially between said skirts (5, 6).