Asymmetrical Cavity Rotary Vane Pump Design
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Solution Overview
Problem
Rotary vane pumps face efficiency and vane life issues at higher vacuum and pressure duties due to limited angular distance for fluid compression, leading to increased noise, heat, and reduced performance.
Innovation Solution
The elliptical cavity shape is altered to shift the angle of maximum vane extension closer to the inlet, increasing the angular distance between the inlet and outlet, and optimizing the inner wall curvature to reduce vane tip load and prevent skipping, resulting in a quieter, cooler, and more efficient pump with longer vane life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the pump uses a standard elliptical cavity with 180° rotation cycle, then the pump achieves greater flow in smaller package size and eliminates side loading, but the angular distance for fluid compression is insufficient leading to increased noise, heat, and reduced efficiency at higher vacuum and pressure duties
Solution Approach 1:
The patent applies asymmetry by modifying the standard elliptical cavity into an asymmetrical cavity where the inlet and outlet ports are positioned at different angular locations. This creates unequal angular distances for the expansion and compression phases, allowing the compression phase to have sufficient angular distance for effective fluid compression while maintaining the compact 180° rotation cycle for high productivity.
2Stress or pressure
If the pump operates at higher vacuum and pressure duties with standard cavity design, then the pump handles higher pressure differentials, but the limited angular distance causes increased noise, heat generation, and reduced efficiency
Solution Approach 1:
The asymmetrical cavity design allows the compression phase to occupy a larger angular portion of the rotation cycle compared to the expansion phase. This provides sufficient angular distance for gradual and effective fluid compression even at high pressure differentials, reducing sudden pressure changes that cause noise and heat generation.
3Device complexity
If the vane extension angle is positioned at the major axis of the ellipse, then the pump follows the standard design, but the angular distance between inlet and outlet is limited restricting internal compression capability
Solution Approach 1:
The patent positions the vane extension angle and port locations asymmetrically within the cavity, shifting them from the standard major axis alignment. This asymmetrical positioning increases the angular distance between inlet and outlet ports, creating larger compression volume while maintaining a relatively simple elliptical-based cavity shape.
4Ease of manufacture
If the inner wall curvature is not optimized, then the cavity follows the standard elliptical shape, but the vane tip load increases and vane skipping occurs reducing vane life
Solution Approach 1:
The patent optimizes the inner wall curvature locally at critical regions where the vanes interact with the cavity wall. By adjusting the curvature radius and profile in these specific areas rather than changing the entire cavity shape, the design reduces vane tip loads and prevents skipping while maintaining ease of manufacture for the overall cavity structure.
Data Source
AI summary
Rotary vane pumps include casings having asymmetrical cavities that accommodate a rotor. For a single pump chamber, one portion of the rotor abuts or nearly abuts the inner wall of the cavity at a single location while one portion of the rotor and the inner wall are not in contact with each other thereby defining a pump chamber. For a dual pump chamber embodiment, two diametrically opposed portions of the rotor abut or nearly abut the inner wall of the cavity while two portions of the rotor and inner wall are not in contact with each other thereby defining the two pump chambers. The two pump chambers are disposed on opposite sides of the minor axis of the cavity. The cavities of each pump are skewed so each pump chamber is larger in volume at the inlet end than at the outlet end.