Dry-running Piston Rod Sealing with Radial Gap Control
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Solution Overview
Problem
Existing dry-running piston rod sealing arrangements face issues with wear, frictional heat, and limited service life due to direct contact with the piston rod, restricting maximum pressure difference and piston speed.
Innovation Solution
A dry-running sealing arrangement with a sealing ring, actuator, and sensor system that allows for controlled radial displacement of the sealing surface relative to the piston rod, maintaining a minimal gap and avoiding direct contact to reduce wear and frictional heat, using a regulating device to manage the position based on measurable values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sealing surface contacts the piston rod to form a rubbing contact seal, then sealing action is achieved, but wear increases and service life is reduced
Solution Approach 1:
A film of gas or lubricant is introduced as an intermediary between the sealing surface and piston rod, allowing sealing to occur through the film rather than direct contact. This mediator reduces wear while maintaining sealing effectiveness.
Solution Approach 2:
The patent utilizes a film of gas (pneumatic principle) between the sealing surfaces to enable sealing without direct solid contact. The gas film acts as a cushion that maintains separation while providing sealing action.
2Reliability
If direct contact sealing is used, then sealing effectiveness is maintained, but frictional heat generation increases
Solution Approach 1:
The gas or lubricant film serves as a thermal intermediary that reduces frictional heat generation by preventing direct metal-to-metal or solid-to-solid contact, while still maintaining sealing effectiveness.
Solution Approach 2:
The patent replaces the mechanical rubbing contact system with a fluid film-based sealing system, substituting mechanical friction with fluid dynamics to reduce heat generation.
3Reliability
If sealing elements are subjected to high mechanical and thermal loading, then sealing capability is maintained, but maximum pressure difference and mean piston speed are restricted
Solution Approach 1:
The patent changes the fundamental operating parameters by transitioning from contact-based sealing to film-based sealing. This parameter change allows the system to operate at higher speeds and pressure differences without excessive wear or heat generation.
Solution Approach 2:
The sealing system becomes dynamic by utilizing the relative motion between the piston rod and sealing element to maintain the film. The system adapts to varying speeds and pressures through the dynamic behavior of the film rather than static contact.
Data Source
AI summary
The invention relates to a dry-running piston rod sealing arrangement (1) for sealing a piston rod (2) mounted in a longitudinally displaceable manner. The sealing arrangement comprises at least one sealing ring (5) having a sealing surface (5a), an actuator (7), a sensor (8), and a chamber ring (3) containing the sealing ring (5). The actuator (7) comprises an active connection in relation to the sealing ring (5), such that the sealing surface (5a) can be radially displaced in relation to the piston rod (2). The actuator (7) can be controlled according to a measuring value detected by the sensor (8).