Internal Gear Pump Rotor Tooth Profile Design
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Solution Overview
Problem
Existing pump rotors face challenges in increasing discharge amount and durability without increasing the outer diameter or axial thickness, leading to issues like increased noise, reduced durability, and pumping loss due to the limitations in tooth profile design and eccentricity.
Innovation Solution
The pump rotor features a tooth profile formed by combinations of elliptical or true-circular tooth-profile formation circles, allowing for increased tooth count without altering the addendum or dedendum diameters, which enhances discharge efficiency, reduces noise, and improves durability by distributing force more evenly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of teeth is increased to increase discharge amount, then the discharge amount increases, but the rotor size must be increased which deteriorates frictional properties
Solution Approach 1:
The invention changes the tooth profile parameters by using elliptical curves instead of traditional circular arcs, allowing the number of teeth to be increased from 6 to 8 without increasing the rotor outer diameter or axial thickness. This parameter change enables higher discharge amount (12.5 cm³/rev vs 11.9 cm³/rev) while maintaining the same rotor size, thus resolving the contradiction between discharge amount and rotor size.
2Productivity
If the amount of eccentricity is increased to increase discharge amount, then the discharge amount increases, but the rotor size increases which deteriorates frictional properties
Solution Approach 1:
The invention optimizes the eccentricity parameter by precisely controlling the elliptical tooth profile parameters (a=2.4mm, b=1.2mm, c=1.8mm) to achieve the optimal eccentricity value of 3.4mm. This allows the discharge amount to be increased to 12.5 cm³/rev while maintaining the rotor outer diameter at φ60.0mm and axial thickness at 15mm, thus resolving the contradiction between discharge amount and rotor size.
3Productivity
If the tooth height is increased to increase discharge amount, then the discharge amount increases, but the connecting portion between addendum and engagement becomes abrupt which reduces durability
Solution Approach 1:
The invention applies elliptical curves with carefully designed curvature radii to the tooth profile, particularly at the connecting portion between the addendum and engagement portions. The engagement portion uses an elliptical curve with radius of curvature that smoothly transitions from the addendum portion, eliminating abrupt changes. This curved transition improves the durability by reducing stress concentration while maintaining the increased tooth height for higher discharge amount.
Solution Approach 2:
The invention changes the curvature radius parameter of the elliptical tooth profile to resolve the contradiction. By setting specific curvature radius values for different portions of the tooth profile (addendum, engagement, dedendum), the design achieves both increased tooth height for higher discharge amount and smooth transitions for improved durability and reduced noise.
4Productivity
If the rotor size is increased to increase discharge amount, then the discharge amount increases, but frictional properties deteriorate and noise increases
Solution Approach 1:
The invention changes the tooth profile geometry parameters using elliptical curves to increase the number of teeth from 6 to 8 while maintaining the same rotor outer diameter and axial thickness. This parameter change increases the discharge amount to 12.5 cm³/rev without increasing the rotor size, thus avoiding the deterioration of frictional properties and reduction of noise that would otherwise occur with larger rotor dimensions.
Data Source
AI summary
A pump rotor is an inner rotor of an internal gear pump, the inner rotor having a tooth profile, wherein a half-tooth portion of the tooth profile is formed of three tooth-profile formation circles that are elliptical or true-circular. Two of the tooth-profile formation circles are a combination of a small tooth-profile formation circle and a large tooth-profile formation circle in which the small tooth-profile formation circle is inscribed and is entirely included. A portion of the small tooth-profile formation circle forms an addendum portion of the half-tooth portion. A portion of the large tooth-profile formation circle in which the small tooth-profile formation circle is inscribed and is entirely included forms an engagement portion of the half-tooth portion. A portion of another tooth-profile formation circle that circumscribes the large tooth-profile formation circle forms a dedendum portion of the half-tooth portion.