Linear Movable Rotary Union With Compact Dual Sealing
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Solution Overview
Problem
Existing rotary unions in semiconductor equipment fail to effectively prevent fluid leakage during both rotational and axial motion, complicating sealing structures, maintenance, and requiring significant installation space.
Innovation Solution
A linear movable rotary union design featuring a driving shaft with fluid supply paths, a middle housing with first sealing members, and an outer housing with second sealing members, allowing rotational and axial motion while minimizing leakage through a simplified sealing structure and reduced size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a rotary union is designed to allow both rotational motion and axial reciprocating motion, then the functionality and versatility are improved, but the sealing structure becomes more complex and difficult to manufacture
Solution Approach 1:
The rotary union is divided into multiple functional segments: a rotating shaft assembly for rotational motion and a reciprocating piston assembly for axial motion. Each segment has its own sealing mechanism (radial seals for rotation, piston seals for reciprocation), allowing independent optimization of each sealing function rather than attempting a single complex sealed structure
Solution Approach 2:
The reciprocating piston assembly is nested within the rotating shaft assembly. The piston moves axially within the shaft while the shaft itself rotates, creating a nested configuration where one motion mechanism is contained within another. This nesting allows both motions to occur simultaneously without requiring separate housings or sealing systems
2Reliability
If traditional sealing structures are used to prevent fluid leakage during motion, then leakage prevention is improved, but the device size increases and installation space is required
Solution Approach 1:
The patent uses flexible sealing elements including O-rings, lip seals, and piston seals made from elastomeric materials. These flexible seals conform to the mating surfaces and maintain sealing contact during both rotational and reciprocating motions without requiring large sealing chambers or rigid sealing structures
Solution Approach 2:
Multiple sealing functions are merged into compact assemblies. The rotating shaft incorporates radial seals at its ends and the piston assembly integrates seals at both ends of the piston rod. This merging of sealing functions into the motion components themselves eliminates the need for separate sealing housings or chambers
3Ease of manufacture
If a simplified sealing structure is used to reduce manufacturing complexity, then ease of manufacture is improved, but fluid leakage during pressure and vacuum states increases
Solution Approach 1:
The sealing system is designed to be self-actuating and self-regulating. Lip seals use the pressure differential across the seal to maintain contact with the rotating shaft. Piston seals use spring pressure and pressure differential to maintain sealing contact during reciprocation. This self-service approach provides reliable sealing without complex adjustment mechanisms or multiple sealing layers
Solution Approach 2:
The sealing effectiveness is maintained across varying pressure conditions by designing seals with appropriate material properties and geometric parameters. The elastomeric seal materials are selected for their ability to maintain elasticity and sealing force across temperature and pressure ranges. Lip seal geometry is optimized to maintain contact pressure during rotation, while piston seal geometry accommodates the reciprocating motion and pressure differential
Data Source
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AI summary
Provided is a linear movable rotary union including a driving shaft comprising a plurality of fluid supply paths; a hollow middle housing surrounding an outside of the driving shaft and comprising a plurality of first through holes in a sidewall; a plurality of first sealing members provided between the middle housing and the driving shaft to prevent leakage of a fluid; a hollow outer housing surrounding an outside of the middle housing and comprising a plurality of second through holes in a sidewall; and a plurality of second sealing members provided between the middle housing and the outer housing to prevent leakage of the fluid, and wherein the driving shaft is installed to be capable of rotational motion in the middle housing, and the middle housing is installed to be capable of reciprocating motion in an axial direction in the outer housing.