Vane Pump Asymmetric Tip Geometry for Wear Reduction
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Solution Overview
Problem
Existing vane pumps face high adhesive wear stresses between vanes and cam blocks due to excess radial pressure loads, which can lead to damage and require complex under-vane pressurization schemes, especially at low speeds where centrifugal forces are insufficient.
Innovation Solution
The vane pump design features a gap between the vane and radial slot, allowing for different angular positions and orientations of the vane tip, providing balanced or biased radial loads without the need for under-vane pressurization, and includes a channel to equalize pressure, reducing wear and pressure pulsations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If under-vane pressurization is applied to maintain seal at low speeds, then sealing is improved, but device complexity and weight increase
Solution Approach 1:
The patent removes the under-vane pressurization system entirely, extracting the harmful complexity and weight while maintaining sealing through a different mechanism - the offset vane tip geometry that creates asymmetric pressure distribution on the vane surfaces to generate outward radial load during seal arc operation
Solution Approach 2:
The vane tip is designed with asymmetric geometry where the centerline is offset from the leading surface, creating unequal surface areas on opposite sides of the vane. This asymmetry generates a net outward radial force during seal arc operation through pressure differential, eliminating the need for separate pressurization systems
2Reliability
If under-vane pressurization is used to maintain seal, then sealing is improved, but weight increases
Solution Approach 1:
The patent eliminates the under-vane pressurization system and its associated weight, replacing it with a geometry-based solution that uses the existing fluid pressure field to generate the necessary sealing force through asymmetric vane tip design
3Reliability
If excess radial pressure load is applied to maintain vane engagement, then engagement is improved, but adhesive wear increases
Solution Approach 1:
The patent creates a dynamic radial load on the vane that varies with operating conditions - the offset geometry generates outward radial force during seal arc operation to maintain engagement, while allowing reduced load during pump arc operation, thereby preventing excessive wear throughout the operational cycle
Solution Approach 2:
The asymmetric vane tip geometry changes the pressure distribution parameters on the vane surfaces, creating a net outward radial force during seal arc operation that maintains proper engagement without the excessive loads that cause adhesive wear
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 design reduces wear and pressure pulsations, maintaining desired radial loads throughout the pump's cycle, eliminating the need for complex under-vane pressurization and enhancing engagement with the cam block, especially at low speeds.
Implementation Method 1
fluid pressure acting on the larger surface 40 and the smaller surface 36 results in a net outward radial load urging the vane into engagement with the cam block inner surface 22
Implementation Method 2
centrifugal force at low operating speeds to reduce or eliminate the need for under-vane pressurization
Implementation Method 3
includes a channel to equalize pressure, reducing wear and pressure pulsations
Implementation Method 4
The tip portion has an arcuate surface that engages with the cam block inner surface to provide a fluid seal point along the arcuate surface
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
A vane pump is disclosed that includes a plurality of vanes and radial slots configured to provide a gap between the vane and the radial slot such that the vane has a different angular position relative to the direction of rotation in a radially extended position compared to an angular position in a radially-retracted position. The different angular positions provide different orientation of the arcuate surface of the vane tip portion with respect to the cam body inner surface, thus providing different fluid stop points on the vane tip portion arcuate surface.