Displacement Pump Backflow Channel for Gas Venting
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Solution Overview
Problem
Displacement pumps face issues with air bubbles forming in the suction line and delivery chamber, leading to disruptions in the metering process due to high gas compressibility, which prevents the pressure valve from opening, resulting in incomplete pumping of the delivery medium.
Innovation Solution
A backflow channel is introduced between the delivery chamber and pressure connection, allowing medium to flow back and gas to escape, even when the pressure valve is closed, to restore the compressibility ratio and ensure proper operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the pressure valve is designed to open only when delivery chamber pressure exceeds pressure line pressure, then delivery medium can be pumped into the pressure line, but air bubbles accumulate in the delivery chamber preventing the pressure valve from opening
Solution Approach 1:
The pressure connection is segmented into two separate pathways: a pressure valve for liquid delivery and a backflow channel for gas venting. This segmentation allows the pressure valve to maintain its pressure-dependent opening behavior for liquid pumping while the backflow channel provides a separate escape route for air bubbles, preventing accumulation and ensuring reliable metering operation.
Solution Approach 2:
The backflow channel acts as an intermediary pathway between the delivery chamber and pressure connection. It mediates the gas accumulation problem by providing a dedicated route for air bubbles to escape without interfering with the pressure valve's liquid delivery function, thus resolving the contradiction between pumping performance and metering reliability.
2Reliability
If an additional bypass line with valve and activation device is added to allow liquid re-entry and gas escape, then gas can be vented from the delivery chamber, but device complexity increases
Solution Approach 1:
The backflow channel merges the degassing function with the existing pressure connection structure. Instead of adding a separate bypass line with valve and activation device, the venting function is integrated directly into the pressure connection pathway, eliminating the need for additional components while maintaining the degassing capability.
Solution Approach 2:
The backflow channel operates passively without requiring external activation. The pressure differential between the delivery chamber and pressure line automatically controls the flow through the backflow channel, allowing the system to self-regulate gas venting without additional valves or activation devices, thus reducing device complexity.
3Reliability
If the backflow channel cross-section is made larger to improve gas escape, then degassing efficiency increases, but pumping efficiency decreases due to medium backflow
Solution Approach 1:
The backflow channel is designed with locally optimized characteristics: a small cross-section (0.01-0.1 mm²) that provides sufficient gas escape pathways while minimizing liquid backflow. The channel's geometry and positioning create local flow conditions that favor gas venting over liquid return, resolving the contradiction between degassing efficiency and pumping efficiency.
Solution Approach 2:
The backflow channel cross-section is optimized to specific parameter ranges (0.01-0.1 mm²) that balance gas venting capability with liquid backflow minimization. This parameter optimization ensures adequate degassing efficiency while maintaining pumping efficiency, avoiding the extremes of too large (excessive backflow) or too small (insufficient venting).
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 solution effectively degasses the delivery chamber, reducing downtime and improving the reliability of the pumping process while maintaining efficient performance by minimizing the impact on pumping efficiency.
Implementation Method 1
a backflow channel connects the delivery chamber and pressure connection to one another, through which delivery medium can flow back from the pressure line into the delivery chamber and/or gas can escape from the delivery chamber into the pressure line
Implementation Method 2
the displacement element is moved back and forth in an oscillating manner between the first and second position. Upon the movement of the displacement element from the first position into the second position, the volume of the delivery chamber is increased
Implementation Method 3
As soon as the pressure in the delivery chamber exceeds the pressure in a pressure line connected to the pressure connection, the pressure valve is opened so the delivery medium located in the delivery chamber can be pressed into the pressure line
Implementation Method 4
If, as a result, the pressure in the delivery chamber drops below the pressure in a suction line connected to the suction connection, the suction valve opens and medium to be delivered is sucked into the delivery chamber via the suction connection
Data Source
AI summary
A displacement pump includes a delivery chamber, connected to a pressure connection and a suction connection. A displacement element determines the volume of the delivery chamber and can be moved back and forth between a first position, in which the delivery chamber has a smaller volume, and a second position, in which the delivery chamber has a larger volume. The pressure connection is connected to the delivery chamber by a pressure valve and the suction connection is connected to the delivery chamber by a suction valve. The displacement pump is easy and economical to produce and simultaneously reliably provides a degassing function, whereby downtimes can be reduced and the reliability of the delivery process can be increased. With the pressure valve closed, a backflow channel connects the delivery chamber and pressure connection, through which medium can enter the delivery chamber and/or gas can escape from the delivery chamber.