Internal Gear Pump Arc Tooth Profile for Slippage Reduction
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Solution Overview
Problem
Internal gear pumps face challenges in size reduction while maintaining discharging capability due to fixed tooth height, which affects efficiency and resistance, and existing solutions do not effectively address slippage issues for improved efficiency.
Innovation Solution
The internal gear pump design features inner and outer teeth with specific arc shapes, allowing adjustable tooth height and reduced slippage, with the relationship between arc radii and pitch circle diameter optimized to minimize slippage and interference, enabling size reduction without compromising discharging capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the size of the internal gear pump is reduced, then weight reduction is achieved, but the discharging capability is reduced
Solution Approach 1:
The patent changes the geometric parameters of the teeth by introducing specific arc shapes with defined radius relationships. The first arc shape on inner teeth and second arc shape on outer teeth, with radius ratios satisfying 0.5 < ro/ri < 2.0, optimize the meshing geometry to reduce slippage and improve discharge efficiency, allowing size reduction without compromising productivity
Solution Approach 2:
The patent applies different arc shapes to specific local regions of the teeth. The first arc shape is applied to the inner teeth while the second arc shape is applied to the outer teeth, creating locally optimized contact surfaces that reduce slippage and improve overall pump performance, enabling weight reduction while maintaining discharging capability
2Object-affected harmful factors
If cycloid curve is used to define tooth shapes, then sliding resistance and rattling are reduced, but the height of teeth cannot be adjusted when the number of teeth is fixed
Solution Approach 1:
The patent segments the tooth profile into distinct arc-shaped portions. The first arc shape and second arc shape are defined as separate geometric entities with independent radius parameters (ro and ri), allowing the tooth height to be adjusted by changing these radius values while maintaining the beneficial sliding resistance characteristics of curved contact surfaces
3Loss of energy
If slippage between outer tooth of inner gear and inner tooth of outer gear is reduced, then efficiency is improved, but specific means for improvement is not available in conventional designs
Solution Approach 1:
The patent reduces slippage loss by optimizing the geometric parameters of the tooth contact surfaces. By defining specific arc shapes with radius relationships (0.5 < ro/ri < 2.0) and positioning constraints (intersecting point location), the design minimizes relative sliding between meshing teeth, thereby reducing energy loss while maintaining manufacturability through clear geometric definitions
Data Source
Figure 2A~2C
Figure 3A~3C
Figure 4A~4D
AI summary
In an internal gear pump that includes an inner gear (10) having outer teeth and an outer gear (20) having inner teeth, either the inner or outer teeth have a shape based on a tooth shape that is respectively formed from a generating curve of the outer or inner teeth. The inner teeth are arc-shaped, the outer teeth are curved-shaped, and both end sections of the curved shape are arc-shaped. If a radius of the arc shape of the inner teeth is set as ro, a radius of the arc shape of each of the corner sections is set as ri, a diameter of a pitch circle (Co) of the inner teeth is set as dp, and the number of the inner teeth is set as z, the inner gear (10) and the outer gear (20) each has a shape that satisfies a relationship established by following equations: 1.6 > ro/(dp/z) > 1.0; and ro/(dp/z) > ri/(dp/z) ≥ 0.13. Each of the inner teeth is provided so that an intersecting point (P1) between one (Cro) of arcs that follow the arc shapes of the adjacent inner teeth and the pitch circle (Co) of the inner teeth and in proximity to the other arc is located outside of the other arc (Cro).