Piston Pump Diaphragm Amplification for Pulsation-Free Metering
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Solution Overview
Problem
Conventional metering discharge pumps experience pulsations during fluid discharge due to the expanding and contracting actions of bellows, which can lead to inaccurate flow rate control, especially in high-cost applications like semiconductor production where precise fluid flow is critical.
Innovation Solution
A metering discharge pump design featuring a piston with a flexible, elliptical diaphragm and a non-compressive indirect medium, where the piston's displacement is amplified by the diaphragm's larger displacement, ensuring constant fluid discharge without pulsations, using pilot pressure to control the flow rate accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a bellows is used to generate suction and discharge pressures, then the pump can achieve metering discharge function, but pulsations occur in the discharged fluid
Solution Approach 1:
The patent introduces a pilot pressure control system as an intermediary mechanism between the bellows and the main fluid flow. The pilot pressure, generated by a separate piston-cylinder system, controls the timing and magnitude of the bellows expansion, thereby mediating the transmission of mechanical energy to the fluid and eliminating direct pulsations.
Solution Approach 2:
The patent employs dynamic control of the bellows expansion through pilot pressure regulation. The bellows is allowed to expand and contract dynamically under controlled pilot pressure, enabling smooth transition between suction and discharge phases while maintaining stable fluid flow characteristics.
2Productivity
If the bellows expands and contracts to generate discharge pressure, then liquid can be discharged from the pump chamber, but flow rate control accuracy deteriorates
Solution Approach 1:
The patent implements a feedback control mechanism where the pilot pressure is regulated based on the actual pump chamber pressure and flow conditions. This feedback system ensures that the bellows expansion is precisely controlled to maintain accurate flow rate discharge, compensating for any variations in fluid viscosity or pressure conditions.
Solution Approach 2:
The patent changes the control parameter from direct mechanical displacement control to pilot pressure-based control. By regulating the pilot pressure parameter, the system achieves precise control over the bellows expansion characteristics, thereby improving flow rate control accuracy while maintaining discharge capability.
3Productivity
If the bellows is used for fluid discharge, then the pump can maintain metering function, but the high cost of coating liquid makes any flow rate variation unacceptable
Solution Approach 1:
The patent applies beforehand cushioning by using the pilot pressure system to pre-regulate the bellows expansion before the main fluid discharge occurs. This preliminary control mechanism cushions against any potential flow rate variations, ensuring consistent and reliable fluid discharge even under varying operating conditions.
Solution Approach 2:
The patent replaces direct mechanical displacement control with a pressure-based control system. The pilot pressure mechanism substitutes for direct mechanical control of the bellows, providing more reliable and consistent flow rate control that is less sensitive to mechanical tolerances and wear, thereby improving reliability for high-value applications.
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 ensures high-accuracy, pulsation-free discharge of a constant fluid amount, eliminating the need for feedback control of pilot pressure and preventing fluid adhesion, thus maintaining precise flow rates in applications like semiconductor coating.
Implementation Method 1
a piston (24) displaceable in an axial direction, and an indirect medium (28) charged in a space between the piston (24) and the diaphragm (48), wherein the piston (24) is displaced in an axial direction under the action of a pilot pressure, and the diaphragm (48) is flexibly bent by the indirect medium (28) displaced by the piston (24)
Implementation Method 2
the diaphragm (48) is flexibly bent by the indirect medium (28) displaced by the piston (24)
Data Source
AI summary
A pump apparatus comprises a piston, which is provided displaceably along a first chamber formed in a body under the action of a pilot pressure, an indirect medium composed of a non-compressive fluid and which is to be pressed by the piston, and a diaphragm that is flexibly bendable in cooperation with the indirect medium. When the fluid is discharged from a discharge port, a change in volume caused by the displacement of the piston in the axial direction is identical to the change in volume caused by the displacement of the diaphragm in the axial direction.