Pump Shaft Sealing via Interference Fit Inserts
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Solution Overview
Problem
Challenges in remanufacturing machine components, such as hydraulic pumps, arise from difficulties in maintaining tight geometric and dimensional tolerances during repair processes, particularly when multiple machines and tools are involved, leading to issues in returning components to a commercially and technically acceptable state.
Innovation Solution
The use of interference fitting inserts with cylindrical inner surfaces within the pump casing bores to precisely position and seal the pump shaft, ensuring effective sealing mechanisms are placed with tolerances similar to those in new parts, achieved through a method involving machining and finish machining of the inserts to maintain coaxial alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If multiple machines and tools are used for machining during remanufacturing, then the repair process can be completed, but maintaining tight geometric and dimensional tolerances becomes difficult
Solution Approach 1:
The pump casing is segmented into modular components with separate bearing chambers that can be independently machined and assembled. This allows each segment to be processed on different machines while maintaining overall tolerance requirements through precision interface design and controlled assembly procedures.
Solution Approach 2:
Precision locating features and reference surfaces act as intermediaries between different machining operations and machines. These intermediary elements transfer and maintain geometric relationships across multiple machining cells, ensuring tight tolerances are preserved even when parts are moved between different machines for processing.
2Ease of repair
If the pump casing is machined on multiple different machines, then the repair can be performed, but locating and controlling the machines becomes difficult
Solution Approach 1:
Reference surfaces and locating features are prepared in advance on the pump casing before machining operations begin. These pre-established geometric references simplify subsequent machining by providing fixed, known positions for tooling and fixtures, reducing the complexity of locating and controlling multiple machines during the repair process.
3Reliability
If sealing mechanisms are positioned in newly formed bores, then sealing integrity can be achieved, but precise positioning and alignment must be maintained
Solution Approach 1:
The sealing mechanisms are designed to self-align within the newly formed bores through interference fits and geometric constraints. The sealing surfaces and bearing surfaces are integrated such that the act of installing the seal automatically positions it correctly, reducing the need for separate precision alignment operations and maintaining tight tolerances through the design itself rather than complex positioning procedures.
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 approach enables the remanufactured pumps to maintain sealing integrity and prevent leakage, ensuring the pump operates effectively with minimal deviation from original specifications, even under harsh conditions, by precisely locating and aligning sealing mechanisms within the pump casing.
Implementation Method 1
a first insert held fast within the first bore via an interference fit, and having a first cylindrical inner surface, and a second insert held fast within the second bore via an interference fit
Data Source
AI summary
A remanufactured pump includes a casing and a pumping mechanism positioned within the casing having a rotatable pump shaft and an impeller mounted upon the pump shaft and rotatable within a pumping chamber in the casing. A first insert is held fast within a first bore in the casing, and a second insert is held fast within a second bore in the casing, each via an interference fit. Sealing mechanisms are positioned within the first and second inserts to form a first seal about the pump shaft to prevent leakage of a working fluid from the pumping chamber, and a second seal about the pump shaft to prevent leakage of a lubricating fluid from a bearing chamber in the casing. Related methodology is also disclosed.