Pump Shaft Sealing with Abradable Protrusion Clearance Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing multi-stage pump assemblies face challenges in sealing between the rotor and stator, leading to leakage issues due to unsuitable seal arrangements that often expand the radial separation, creating a circumferential leakage path.
Innovation Solution
The implementation of a protrusion extending radially into the bore between the rotor shaft and stator, formed from different hardness materials, which abrades to create a close seal by wearing away the softer material, maintaining tight tolerances to prevent fluid leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing seal arrangements are used between rotor and stator, then the seal structure is provided, but the radial separation between rotor and stator expands, creating a circumferential leakage path
Solution Approach 1:
The seal arrangement is segmented into multiple functional elements: a seal member with sealing surfaces, a protrusion element extending from the rotor or stator, and a corresponding recess or groove. This segmentation allows each element to perform its specific function while maintaining tight tolerances and preventing circumferential leakage without requiring excessive radial separation.
Solution Approach 2:
The seal member acts as an intermediary element between the rotor and stator, providing a dedicated sealing interface. The protrusion element and corresponding recess work together as intermediary features that guide and maintain the seal, enabling effective sealing while minimizing the radial space required between rotating and stationary components.
2Reliability
If tight tolerances are maintained to prevent leakage, then sealing is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The seal arrangement applies local quality by concentrating sealing functionality at specific localized interfaces (sealing surfaces, protrusion-recess interfaces) rather than requiring tight tolerances across the entire rotor-stator interface. This allows tight tolerances to be applied only where critical for sealing, while other areas can be manufactured with more relaxed tolerances.
Solution Approach 2:
The protrusion element and corresponding recess are designed to preliminarily establish the correct positioning and alignment of the seal member before final assembly. This preliminary action ensures that the sealing surfaces engage properly, reducing the need for extremely tight manufacturing tolerances across all components.
3Strength
If the protrusion and bore portion are formed from different hardness materials, then wear resistance is enhanced through abrasion, but manufacturing complexity increases
Solution Approach 1:
The seal arrangement utilizes parameter changes by selecting materials with different hardness properties for the protrusion element and bore portion. This creates a deliberate hardness differential that controls wear patterns during operation, with the harder material resisting wear while the softer material can be replaced if needed, enhancing overall wear resistance of the seal system.
Solution Approach 2:
The seal arrangement employs composite material selection, combining materials with different properties (different hardness) in the protrusion element and bore portion. This composite approach allows each material to be optimized for its specific function, with the harder material providing wear resistance and the softer material providing ease of manufacture or replaceability.
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 effectively reduces axial and circumferential leakage by maintaining a close seal between the rotor and stator, enhancing the sealing mechanism and allowing for smaller stage sizes in multi-stage pumps, thereby reducing power consumption.
Implementation Method 1
contact between the protrusion and the one of the bore portion and the rotor shaft portion abrades the softer material
Implementation Method 2
the softer material may be worn away by the harder material to provide a close, rotatable seal
Data Source
Figure 1
Figure 2a
Figure 2b~3
AI summary
A pump assembly is disclosed. The pump assembly comprises: a rotor (50) having a rotor shaft portion (80); a stator (100) having a bore portion defining a bore for receiving the rotor shaft portion; and a circumferential protrusion extending radially into the bore between the bore portion and the rotor shaft portion, wherein at least one of the protrusion and a corresponding surface of the rotor shaft portion or the bore portion is configured to be abraded by the other upon experiencing contact therewith. In this way, the gap between the bore portion and the rotor shaft portion may be at least partially filled by the circumferential protrusion in order to provide a seal. The protrusion and one of the bore portion and the rotor shaft portion may be formed from different hardness materials. Providing different hardness materials enables any contact between the protrusion and the bore portion or the rotor shaft portion to cause wear between the two in order to enhance the seal.