Piston Flat Depth Coordination with Liner Port Diameter
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Solution Overview
Problem
Positive displacement pumps face limitations in achieving high fluid flow rates due to arbitrary selection of liner port diameters and piston flat depths, leading to increased flow resistance and cavitation, especially when trying to exceed specified flow limits within constrained spaces.
Innovation Solution
The design optimizes the relationship between liner port diameters and piston flat depths by using a hydraulic diameter calculation (Dh = 4A/P) to match flow resistance across the fluid path, ensuring the distance from the piston centerline to the flat surface is at least half the port diameter, thereby reducing pressure changes and cavitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the pump speed and stroke are increased to achieve high flow rates, then the fluid output increases, but the pump size and constraints are exceeded
Solution Approach 1:
The patent changes the geometric parameters of the piston flat and liner port to optimize fluid flow. Specifically, it defines the piston flat depth as a function of the liner port diameter (depth ≥ 0.5 × port diameter) and matches the hydraulic diameter of the D-shaped channel to the port diameter, thereby improving flow rates within the same pump size constraints.
2Ease of manufacture
If the liner port diameter is arbitrarily chosen for manufacturing convenience, then the ease of manufacture increases, but the flow resistance increases and high-flow performance is limited
Solution Approach 1:
The patent establishes a specific relationship between the liner port diameter and piston flat depth (depth ≥ 0.5 × port diameter) to optimize flow characteristics. This parameter coordination allows selecting convenient port diameters while ensuring the piston flat depth is sufficient to maintain low flow resistance and prevent cavitation.
3Reliability
If the piston flat depth is made as deep as possible to prevent blow-by, then the reliability increases, but the flow resistance increases and cavitation occurs
Solution Approach 1:
The patent defines an optimal range for piston flat depth as a function of liner port diameter (depth ≥ 0.5 × port diameter), which prevents blow-by conditions while avoiding excessive depth that would cause flow resistance and cavitation. This coordinated parameter design balances reliability and flow performance.
4Productivity
If the hydraulic diameter of the cut-out portion is matched to the inlet bore diameter, then the flow resistance is reduced, but the manufacturing precision requirements increase
Solution Approach 1:
The patent establishes a clear mathematical relationship between the hydraulic diameter of the D-shaped cut-out (Dh = 4A/P) and the liner port diameter, requiring Dh to equal the port diameter. This provides a precise design criterion that guides manufacturing while minimizing flow resistance.
Data Source
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AI summary
A liquid pump having a pump liner and a pump piston, wherein the pump liner defines a central longitudinal bore and a transverse inlet bore communicating with the central bore for conveying a liquid. The pump piston has a centerline intersecting with a centerline of the transverse inlet bore, and further has a flat surface formed parallel with the piston centerline at a distal end of the piston. The flat surface defines a cut-out portion of the piston, wherein the cut-out portion has a hydraulic diameter equal to the diameter of the transverse inlet bore of the liner, and a distance from the centerline of the piston to the flat surface defining the cut-out portion is greater than or equal to 1/2 of the diameter of the transverse inlet bore of the liner.