Internal Gear Pump With Blind Pockets for Lower Startup Friction
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Solution Overview
Problem
Rotary pumps with a radially mounted outer rotor face start-up issues due to high friction and viscous friction, leading to inefficiency and potential damage, and require costly high-precision machining to minimize these forces.
Innovation Solution
The rotary pump design features an eccentric inner and outer rotor with blind pockets on the peripheral bearing wall and outer rotor, reducing friction by fluidically separating the pockets and minimizing contact areas, thus reducing drive power and manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If high-precision machining is applied to the outer rotor and peripheral bearing wall surfaces, then adhesive and frictional forces are minimized, but manufacturing cost and time increase significantly
Solution Approach 1:
The peripheral bearing wall is segmented into multiple blind pockets that are radially open towards the outer rotor. This segmentation creates discrete lubrication zones that reduce the need for high-precision continuous surface machining, thereby lowering manufacturing costs while maintaining low friction through localized fluid reservoirs
Solution Approach 2:
A lubricating fluid is introduced as an intermediary substance between the outer rotor and peripheral bearing wall surfaces. The fluid fills the blind pockets and reduces direct contact friction, allowing the use of less precisely machined surfaces while still achieving low adhesive and frictional forces
2Loss of energy
If the lubrication gap between outer rotor and peripheral bearing wall is minimized, then viscous friction is reduced, but manufacturing precision requirements and costs increase
Solution Approach 1:
The blind pockets in the peripheral bearing wall are designed with specific dimensional parameters (radial opening towards outer rotor, controlled depth) that optimize fluid retention and distribution. These parameter changes allow for a larger, more tolerant lubrication gap while maintaining effective lubrication and minimizing viscous friction through proper fluid management in the pockets
3Device complexity
If conventional radial mounting is used for the outer rotor, then structural simplicity is maintained, but start-up performance is poor due to high friction
Solution Approach 1:
The blind pockets are pre-filled with lubricating fluid before operation begins. This preliminary action ensures that when the pump starts up, the outer rotor immediately encounters reduced friction conditions rather than dry startup conditions, significantly improving start-up performance while maintaining the simple radial mounting structure
Solution Approach 2:
A lubricating fluid system is implemented using hydraulic principles, where the fluid is supplied to and retained in the blind pockets of the peripheral bearing wall. This hydraulic lubrication system reduces friction during startup and operation without requiring complex structural changes to the radial mounting arrangement
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 design enhances start-up performance, reduces drive power consumption, and lowers manufacturing costs by minimizing friction and the need for precise machining.
Implementation Method 1
the blind pockets are fluidically separated from one another in the region of the sliding contact between the outer rotor and the peripheral bearing wall
Implementation Method 2
the fluid in the lubrication gap between the outer peripheral surface of the outer rotor and the inner peripheral surface of the peripheral bearing wall can generate viscous friction, especially at high speeds
Implementation Method 3
the viscous friction results primarily from the adhesion of the fluid to the stationary inner peripheral surface of the peripheral bearing wall and the moving outer peripheral wall of the outer rotor
Implementation Method 4
The rotary pump comprises a housing with a conveying chamber, which the housing surrounds and axially delimits at the end faces. The conveying chamber has at least one inlet for the fluid on a low-pressure side of the rotary pump and one outlet for the fluid on the high-pressure side of the rotary pump
Data Source
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AI summary
Rotary pump comprising: a housing (1) with a pumping chamber (5) which the housing (1) surrounds and axially delimits at its end faces and which has an inlet (6) for the fluid on a low-pressure side of the rotary pump and an outlet (7) for the fluid on a high-pressure side of the rotary pump, an inner rotor (4) rotatable in the pumping chamber (5), an outer rotor (3) rotatable in the pumping chamber (5) about a pump axis of rotation (R3) and forming pumping cells with the inner rotor (4), and a circumferential bearing wall (2) formed by or arranged in the housing (1), which surrounds the outer rotor (3) and rotatably supports it in a radial sliding contact about the pump axis of rotation (R3), wherein the circumferential bearing wall (2) has several blind pockets (21, 22, 23, 24) radially open to the outer rotor (3) and/or the outer rotor (3) has several blind pockets (21, 22, 23, 24) radially open to the circumferential bearing wall (2). 22, 23, 24) shows,which are fluidically separated from each other in the area of the sliding contact between the outer rotor (3) and the circumferential bearing wall (2).