Scroll Pump Axial Compliance Flexure Seal Life
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Solution Overview
Problem
Non-energized tip seals in scroll pumps require precise axial positioning to ensure effective sealing, but this can lead to overloading and damage if the gap is too small, and maintaining narrow tolerances is challenging, limiting their useful life and assembly flexibility.
Innovation Solution
Incorporating an axial compliance system with a flexure and springs that allows for axial movement between the eccentric drive mechanism and bearings, enabling the tip seals to maintain an effective seal across a wider range of axial dimensions without overloading or damaging components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If non-energized tip seals are used in scroll pumps, then the seal life is extended compared to spring-biased seals, but the axial positioning precision must be maintained within narrow ranges to prevent overloading and damage
Solution Approach 1:
The patent introduces a spring mechanism that provides axial compliance, allowing the tip seal to dynamically adjust its position along the axial direction. This dynamic adjustment capability enables the seal to accommodate variations in axial positioning while maintaining effective sealing, thus resolving the contradiction between extended seal life and the requirement for narrow axial positioning tolerances
Solution Approach 2:
The spring mechanism changes the axial position parameter of the tip seal dynamically, allowing it to adapt to different axial gaps. By varying the axial position within a certain range, the system maintains optimal sealing contact without requiring precise fixed positioning, thereby extending seal life while relaxing manufacturing precision requirements
2Reliability
If the axial gap between tip seal and opposing scroll plate is reduced to improve sealing, then sealing performance is enhanced, but the risk of overloading and damaging components increases
Solution Approach 1:
The spring provides dynamic axial compliance that allows the tip seal to maintain optimal contact pressure with the opposing scroll plate. This dynamic adjustment ensures reliable sealing while preventing excessive contact pressure that could lead to overloading and component damage, thus resolving the contradiction between sealing performance and component durability
Solution Approach 2:
The spring mechanism acts as a cushioning element that prevents the tip seal from making rigid, high-stress contact with the opposing scroll plate. By providing elastic compliance beforehand, the spring cushions against potential overloading conditions, ensuring both effective sealing and protection of components from damage
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 axial compliance system ensures optimal sealing performance while allowing for assembly with less precise axial positioning, reducing the risk of overloading and extending the life of the tip seals by accommodating variations in axial dimensions, thus enhancing the reliability and durability of the scroll pump.
Implementation Method 1
a spring element (e.g., a disc spring or Belleville washer) biased between the orbiting plate scroll and the stationary plate scroll in the axial direction
Implementation Method 2
an axial compliance system including at least one spring and a flexure having compliance in the axial direction of the pump
Data Source
AI summary
A scroll pump includes a frame, a stationary plate scroll, an orbiting plate scroll, a non-energized type of tip seal or seals, an eccentric drive mechanism assembled to and supported by the frame and to which the orbiting plate scroll is assembled so as to be drivable by the eccentric drive mechanism in an orbit about a longitudinal axis of the pump, and an axial compliance system including a flexure. The flexure is interposed between a bearing of the eccentric drive mechanism and a flexure-locating surface of the eccentric drive mechanism. The flexure allows the orbiting plate scroll to move away from the stationary plate scroll in the case of an assembly process which would otherwise result in the tip seal(s) being too forcefully engaged with the plate of the opposing plate scroll.