Piston With Replaceable Inserts For Pump Wear Reduction
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Solution Overview
Problem
Positive-displacement pumps face issues with wear and galling due to close fits between pistons and housing, leading to potential damage and high costs from using non-galling materials, which are expensive and wear rapidly in abrasive applications.
Innovation Solution
A piston design featuring replaceable and adjustable outer surfaces with inserts made of non-galling materials, coupled to a hub portion using fasteners and shims for adjustability, allowing for a close fit without the need for expensive materials across the entire piston.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a relatively close fit is provided between the piston and housing, then semi-solids and solids are prevented from accumulating and pump pressure is improved, but wear and galling of the piston and housing surfaces occur
Solution Approach 1:
The piston is divided into a hub portion and replaceable insert portions. The insert portions are separable components that can be independently replaced when worn, while the hub portion remains. This segmentation allows the sealing surface to be renewed without replacing the entire piston, resolving the contradiction by enabling sustained close-fit operation while providing a cost-effective replacement mechanism for worn surfaces.
Solution Approach 2:
The invention allows adjustment of the distance between the hub portion center and the outer surface of inserts using shims. This parameter adjustment capability enables optimization of the fit between piston and housing to prevent accumulation of materials while maintaining appropriate clearance to reduce wear and galling effects.
2Object-affected harmful factors
If non-galling materials are used for the piston, then galling of surfaces is prevented, but the cost increases and wear in abrasive applications occurs
Solution Approach 1:
Instead of making the entire piston from expensive non-galling materials, the invention applies non-galling material properties only to the insert portions that contact the housing. The hub portion can be made from less expensive materials. This local application of special material properties reduces overall cost while still preventing galling at the critical contact surfaces.
Solution Approach 2:
The insert portions are designed as replaceable components that can be economically replaced when worn or galled, rather than replacing the entire expensive piston. This allows use of non-galling materials in the inserts to prevent surface damage while providing a cost-effective maintenance strategy through selective replacement of only the worn insert portions.
3Power
If a relatively close fit is provided between the piston and housing, then the pump becomes self-priming and higher pressure is achieved, but the piston and housing surfaces gall
Solution Approach 1:
The invention provides adjustability of the fit between piston and housing through shims, allowing the system to adapt to different operating conditions. The distance between the hub portion center and insert outer surface can be adjusted to optimize the balance between achieving sufficient seal for high pressure and self-priming operation, while preventing excessive clearance that would cause galling.
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
A piston for a pump includes a hub portion defining opposing outer surfaces and concave lateral portions between the opposing outer surfaces. The piston also includes inserts configured to provide a replaceable surface, the inserts being coupled to each of the opposing outer surfaces. A pump includes a housing having an inlet and an outlet, and at least two pistons having a hub portion and inserts. The pump may be a positive-displacement, rotary pump, and the pistons may be circumferential pistons.