Fuel Pump Impeller Clearance Design for Wear Reduction
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Solution Overview
Problem
In existing fuel pumps, the impeller and case tend to wear easily due to restricted movement and inclination, resulting from contact at multiple points, which limits the impeller's ability to relieve its inclination and move freely.
Innovation Solution
The fuel pump design features an output end portion with a pair of first plane surfaces and a fitting hole with a pair of second plane surfaces, where the clearances between these surfaces are made larger in the axial direction, allowing the impeller to oscillate and relieve its inclination, reducing wear and contact-induced vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the output end portion and impeller are constructed with multiple contact points (D cut shaft and D cut hole), then the impeller is restricted in movement and cannot relieve its inclination, but the impeller and case become easily worn
Solution Approach 1:
The contact interface between the output end portion and impeller is segmented into multiple plane surfaces (first plane surfaces on the output end portion and second plane surfaces on the impeller) positioned at different circumferential locations. This segmentation allows the impeller to contact the output end portion at multiple discrete points rather than along a continuous surface, providing both stability and the ability to oscillate for relieving inclination.
Solution Approach 2:
The clearance between the first and second plane surfaces is designed to be larger from one axial side to the other, creating an asymmetric clearance distribution. This dynamic clearance design allows the impeller to oscillate within the clearance space, enabling it to relieve inclination dynamically during operation while maintaining reliable contact for power transmission.
2Stability of the object's composition
If the impeller is restricted in movement by multiple contact points, then the structural stability is improved, but the impeller cannot easily relieve its inclination and wear increases
Solution Approach 1:
Different regions of the contact interface have different clearance characteristics. The clearance between the first and second plane surfaces varies in the axial direction, with larger clearance at one end and smaller clearance at the other end. This local quality variation allows the impeller to be positioned stably while still having the freedom to oscillate locally to relieve inclination.
Solution Approach 2:
The problem of impeller inclination relief is solved by introducing movement freedom in the axial dimension through the asymmetric clearance design. While the impeller is constrained radially by the plane surfaces, it can oscillate axially within the clearance space, adding a dimensional degree of freedom that enables inclination relief without compromising radial positioning stability.
Data Source
AI summary
An outer wall surface of an output end portion includes a pair of first plane surfaces which are formed at different positions in its circumferential direction. An inner wall surface of a fitting hole includes a pair of second plane surfaces which are formed at different positions in the circumferential direction. A clearance between one of the pair of first plane surfaces and one of the pair of second plane surfaces is made larger from one side toward the other side in an axial direction in a state that a rotary shaft and an impeller are concentric with each other.