Bearing Carrier Radial Stiffness Axial Flexibility Scroll Pump
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Solution Overview
Problem
Existing scroll pumps experience damage and frequent bearing replacement due to axial and radial loading, which increases the cost of ownership, especially when not lubricated and under thermal expansion variations.
Innovation Solution
A bearing assembly with a carrier that is stiff radially to maintain scroll alignment and flexible axially to accommodate thermal expansion, featuring a bearing carrier with a radial outer portion fixed to the housing and an inner portion fixed to the bearing, allowing axial movement while resisting radial movement, thereby reducing fretting damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the bearing carrier is made rigid to prevent radial movement, then radial alignment between scrolls is maintained, but axial movement is restricted causing fretting damage
Solution Approach 1:
The bearing carrier transitions from a static rigid structure to a dynamic structure that can adapt its stiffness characteristics. The resilient element allows the carrier to be flexible axially to accommodate thermal expansion while remaining stiff radially to maintain scroll alignment, resolving the contradiction between maintaining precision and preventing damage.
Solution Approach 2:
The patent changes the mechanical parameter of the bearing carrier from completely rigid to selectively flexible by introducing a resilient element. This allows the carrier to exhibit different stiffness characteristics in different directions (radial vs axial), enabling it to simultaneously maintain radial alignment while accommodating axial movement.
2Adaptability or versatility
If the bearing carrier is made flexible axially to accommodate thermal expansion, then thermal variations are accommodated, but radial stability is reduced causing misalignment
Solution Approach 1:
The bearing carrier is designed with non-uniform structural properties - the resilient element provides flexibility specifically in the axial direction while the overall carrier structure maintains radial stiffness. This local differentiation of mechanical properties allows the carrier to be flexible where needed (axial) while remaining stable where required (radial).
3Device complexity
If conventional rigid bearing carriers are used, then structural simplicity is maintained, but frequent bearing replacement is required increasing operational costs
Solution Approach 1:
The bearing carrier incorporates a resilient element (such as a rubber or polymer component) combined with rigid structural elements. This composite construction provides both the flexibility needed to accommodate thermal expansion and the radial stiffness required to maintain alignment, while significantly reducing fretting damage and extending bearing life.
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 solution extends the bearing replacement intervals by maintaining precise axial and radial clearances between scrolls, reducing the risk of misalignment and damage from thermal expansion, thus lowering operational costs.
Implementation Method 1
a resilient element (144) allowing axial movement of the bearing (38, 40) to accommodate thermal expansion of the shaft (14)
Implementation Method 2
The preloaded bearing carrier is flexible in an axial direction to allow axial movement of the bearing
Data Source
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AI summary
The present invention relates to a pump (10) comprising a shaft (15) supported for rotation by a bearing (38) carried by a bearing carrier (48), said bearing carrier having a generally outer radial portion (52) which is fixed relative to a pump housing (12) and a generally inner radial portion (54) which is fixed relative to the bearing, wherein the carrier is stiff in a radial direction between said inner and outer portions and flexible in an axial direction for restraining radial movement of the bearing and allowing axial movement.