Sliding-Vane Pump Rotor Mounting Without Oldham Coupling
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Solution Overview
Problem
Existing sliding-vane pumps require complex and expensive Oldham couplings to compensate for tolerances between the conveyor rotor and drive shaft, leading to a costly and intricate structure.
Innovation Solution
A simplified structure is achieved by directly mounting the conveyor rotor on the drive shaft, utilizing a bearing concept that eliminates the need for a coupling and incorporates a plastic housing and conveyor rotor with different thermal expansion coefficients to manage friction and leakage across temperature variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an Oldham coupling is used to compensate for tolerances between the conveyor rotor and drive shaft, then concentricity precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The invention extracts and eliminates the Oldham coupling from the pump structure. Instead of adding a compensation mechanism, the patent directly mounts the conveyor rotor on the drive shaft, accepting the inherent tolerance limits of direct mounting. This removal of the coupling simplifies the structure while maintaining sufficient concentricity for low-pressure applications.
Solution Approach 2:
The invention accepts limited concentricity precision as tolerable for low-pressure pump applications, eliminating the need for expensive precision compensation mechanisms. The design prioritizes cost-effectiveness and simplicity over high-precision concentricity, using standard manufacturing tolerances that are sufficient for the intended application range.
2Ease of manufacture
If plastic materials are used for housing and conveyor rotor, then manufacturing cost is reduced, but friction and leakage increase under certain conditions
Solution Approach 1:
The invention exploits temperature-dependent parameter changes in plastic materials. The different thermal expansion coefficients of the conveyor rotor and housing materials are leveraged to dynamically adjust the clearance between these components. At operating temperatures, the plastic conveyor rotor expands relative to the housing, reducing clearance to prevent leakage while maintaining acceptable friction levels through the lubricating effect of the conveyed fluid.
3Device complexity
If the conveyor rotor is directly mounted on the drive shaft, then device complexity is reduced, but tolerance compensation capability is lost
Solution Approach 1:
The invention employs self-compensation through thermal expansion. The plastic conveyor rotor automatically adjusts its dimensional parameters in response to temperature changes, self-regulating the clearance with the housing without requiring external compensation mechanisms. This self-service approach maintains functional precision despite the simplified direct mounting structure.
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 design results in a more stable, low-cost, and efficient sliding-vane pump with reduced friction and leakage, allowing for compact construction and high volume flow without the need for additional compensation elements.
Implementation Method 1
the conveyor rotor is formed from a material which has a higher coefficient of thermal expansion than the material from which the housing is formed. At low temperatures, when the conveyed medium is more viscous, the conveyor rotor has a greater distance from the housing than at high temperatures, whereby friction of the conveyor rotor on the housing is reduced. Leakage at low temperatures is prevented by the viscosity of the fluid or is only so low that this does not adversely affect the function of the sliding-vane pump. At high temperatures, when the conveyed medium is less viscous, the conveyor rotor lies against the housing with less play and thus reliably prevents leakage
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A sliding-vane pump (10) is described, with a housing (16) in which a cylindrical fluid chamber (14) is formed, a conveyor rotor (28) which is rotatable in the fluid chamber (14) and is guided on a circumferential wall (30) of the fluid chamber (14), wherein in the fluid chamber (14), the conveyor rotor (28) delimits at least one conveyor chamber (32, 33, 34, 35, 36) having a volume which is variable by rotation of the conveyor rotor (28), and with a drive motor (22) having a rotor (24) which is attached rotationally fixedly on a drive shaft (26), wherein the conveyor rotor (28) is arranged positionally fixedly on the drive shaft (26) and the drive shaft (26) is radially mounted in the housing (16) by means of the conveyor rotor (28).