Crosslinked Fluororesin Coated Rotor for Internal Gear Pump
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Solution Overview
Problem
Existing internal gear pumps face instability in pump performance due to difficulties in accurately managing the clearance between the external and internal teeth of the rotor surfaces when coating with crosslinked fluororesin, leading to potential seizure and performance issues.
Innovation Solution
A crosslinked fluororesin-coated rotor manufacturing method that selectively coats the side surfaces of the outer and inner rotors with crosslinked fluororesin, using masking jigs to ensure precise application and prevent coating on critical surfaces, thereby stabilizing the tip clearance and preventing seizure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the side clearance is made small to increase discharge amount, then the leak amount decreases and discharge amount increases, but seizure easily occurs between the side surface and housing
Solution Approach 1:
The patent applies different surface treatments to different parts of the rotor. The sliding surface (side surface) is coated with crosslinked fluororesin to provide low friction and prevent seizure, while the tooth surfaces are left uncoated to maintain accurate meshing and clearance. This local differentiation allows the side clearance to be reduced for higher discharge amount while the coated sliding surface prevents seizure.
2Reliability
If the entire rotor surface is coated with crosslinked fluororesin to prevent seizure, then seizure is prevented, but the tip clearance between teeth becomes unstable and pump performance becomes unstable
Solution Approach 1:
The patent selectively coats only the sliding surface (side surface) of the rotor with crosslinked fluororesin, while leaving the tooth surfaces (inner peripheral surface of outer rotor and outer peripheral surface of inner rotor) uncoated. This ensures that the tip clearance between meshing teeth remains stable and predictable, while the coated sliding surface provides seizure prevention. The masking jig with positioning fitting tooth portion enables precise application of the coating only where needed.
3Reliability
If the side clearance is set to several tens of micrometers or more to prevent seizure, then seizure is prevented, but the leak amount increases and discharge amount decreases
Solution Approach 1:
The patent changes the surface properties of the sliding surface by coating it with crosslinked fluororesin, which has low friction coefficient and high wear resistance. This parameter change in surface characteristics allows the side clearance to be reduced to a few micrometers or less, thereby reducing leak amount and increasing discharge amount, while the coated surface continues to prevent seizure.
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
The method allows for the manufacture of internal gear pumps with stable performance and long-term prevention of rotor seizure by ensuring accurate fluororesin application, maintaining efficient operation even with small clearances.
Implementation Method 1
irradiating the fluororesin with radiation in a state where the outer masking jig is removed from the outer rotor, to crosslink the fluororesin
Data Source
AI summary
A crosslinked fluororesin-coated rotor manufacturing method is a method for manufacturing an annular outer rotor of an internal gear pump including the outer rotor, and an inner rotor, a side surfaces of the outer rotor being coated with a crosslinked fluororesin, an inner peripheral surface of the outer rotor not being coated with the crosslinked fluororesin, the method including: using an outer masking jig for covering the inner peripheral surface in a state where the side surfaces of the outer rotor are exposed; coating the outer rotor with an uncrosslinked fluororesin in a state where the outer masking jig is mounted to the outer rotor; and then irradiating the fluororesin with radiation in a state where the outer masking jig is removed from the outer rotor, to crosslink the fluororesin.