Gear Pump Tooth Profile Design for Noiseless Operation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing positive displacement gear pumps face issues with noise, pressure ripple, and limited displacement due to discontinuous fluid delivery and fluid compression, which affect efficiency and operational reliability.
Innovation Solution
A tooth profile design for gear pumps with involute stub-tooth profiles and circular segments for inactive tooth profiles, optimized with specific contact ratios and pressure angles to ensure continuous motion and minimize interference, reducing noise and pressure oscillations, and increasing displacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If involute profiles are used for gear teeth, then conjugate profiles and constant velocity ratio are ensured, but fluid compression and pressure ripple occur due to volume trapped during meshing
Solution Approach 1:
The tooth profile is segmented into three distinct sections: an active right-handed flank with involute stub-tooth profile, an active left-handed flank with involute stub-tooth profile, and inactive portions with circular segments. This segmentation allows the active sections to provide conjugate profiles for constant velocity ratio while the inactive circular sections prevent fluid compression by ensuring proper meshing clearance.
Solution Approach 2:
Different portions of the tooth profile are assigned different geometric qualities: the active flanks use involute profiles for conjugate action and constant velocity ratio, while the inactive tooth top and bottom use circular segments with specific radii to prevent fluid trapping. This local differentiation resolves the contradiction by optimizing each section for its specific function.
2Ease of manufacture
If standard tooth profiles with circular tooth top and bottom are used, then manufacturing is simplified, but discontinuous fluid delivery causes pressure oscillations and limits displacement
Solution Approach 1:
The invention changes the geometric parameters of the tooth profile by using involute stub-tooth profiles with specific contact ratios (εt=0.4-0.5) instead of standard full-depth involute profiles. The inactive portions use circular segments with radii specifically calculated to ensure continuous meshing. This parameter optimization enables both ease of manufacture and continuous fluid delivery.
Solution Approach 2:
The involute stub-tooth profiles are designed with contact ratios that ensure continuous engagement between gear teeth throughout the meshing cycle. This continuity eliminates the discontinuous fluid delivery and pressure oscillations associated with standard tooth profiles, while maintaining manufacturability through well-established gear manufacturing processes.
3Reliability
If minimum number of gear teeth is increased to avoid interference, then cutting and operating non-interference is ensured, but pump displacement and total delivery are limited
Solution Approach 1:
The invention uses involute stub-tooth profiles with reduced contact ratios (εt=0.4-0.5) and specific pressure angles (αt=25°-40°) that allow operation with fewer teeth (z=6-8) without interference. The inactive circular portions with properly calculated radii prevent interference while enabling lower tooth counts, thereby increasing pump displacement and delivery capacity.
Data Source
AI summary
The present invention deals with the analytical definition of a tooth profile for rotors used in gear pumps. The purpose is to obtain a pump characterized by noiseless operation, minimization of vibrations and pressure overoscillations generated in operating conditions at the beginning and end of life, and high specific displacement, in such a way to increase the delivery of the pump in given volume conditions. This profile is characterized by an active profile of the tooth flanks with involute stub-tooth with transverse contact ratio (εt) comprised in the range from 0.4 to 0.45, helical teeth with helical contact ratio (εβ) comprised in the range from 0.6 to 0.85, circular inactive tooth bottom and top profiles, with center (Of, Ot) and radius (rf, rt) defined by a non-dimensional parameter ζ in the range from 1.1 to 1.6.