Internal Gear Pump Rotor Tooth Profile Design
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Solution Overview
Problem
Internal gear pumps with trochoidal tooth profiles face challenges in reducing noise and preventing addendum abrasion while increasing discharge performance, as the narrow addenda lead to increased noise and abrasion issues.
Innovation Solution
The tooth profile of the inner rotor is formed by a rolling circle along a base circle with a changing diameter of the locus circle from the addendum to the dedendum point, ensuring a larger diameter at the dedendum point than at the addendum point, and the rotors are designed with a specific ratio and angle configuration to reduce noise and abrasion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the tooth height of the rotors is increased to increase pump chamber capacity and discharge performance, then the discharge rate is improved, but noise caused by gear rattling increases
Solution Approach 1:
The invention applies different radii of curvature to different portions of the tooth profile. Specifically, the addendum portion has a larger radius of curvature than the dedendum portion, creating local quality variations that reduce stress concentration and gear rattling noise while maintaining the increased tooth height needed for higher discharge performance
2Ease of manufacture
If the tooth profile is formed with a trochoidal curve using a constant diameter locus circle, then the manufacturing is simplified, but the addendum becomes narrow leading to addendum abrasion
Solution Approach 1:
The invention varies the radius of curvature locally along the tooth profile, with the addendum portion having a larger radius than the dedendum portion. This local quality differentiation widens the addendum area, improving resistance to addendum abrasion while maintaining manufacturability through a controlled variation in the locus circle diameter
3Reliability
If the diameter of the locus circle is changed from the addendum to dedendum point, then the addendum width is increased to reduce abrasion, but the manufacturing complexity increases
Solution Approach 1:
The invention changes the parameter of the locus circle diameter along the tooth profile generation process. The diameter varies from a first value at the addendum point to a second value at the dedendum point, creating a continuous parameter change that widens the addendum while maintaining a systematic and controllable manufacturing process
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 configuration increases the pump chamber capacity, reduces noise, and suppresses addendum abrasion, enhancing the discharge performance and operational stability of the internal gear pump.
Implementation Method 1
when a rolling circle having a diameter d1 is rolled along a base circle having a diameter d without slipping and a trochoidal curve is drawn
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
A tooth profile of an inner rotor 2 is formed by an envelope of a group of circular arcs of a locus circle C having a center on a trochoidal curve TC. The envelope of the group of circular arcs is formed by rolling a rolling circle having a predetermined diameter along a base circle without slipping and drawing the trochoidal curve TC based on a point distant from the center of the rolling circle by a distance equivalent to an amount of eccentricity between the two rotors. A diameter d2 of the locus circle C is constant until one point between an addendum point and a dedendum point of the inner rotor and changes from the one point such that a diameter d2B at the dedendum point becomes larger than a diameter d2T at the addendum point of the inner rotor.