Positive Displacement Pump Piston Sleeve Pressure Sensor Protection
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Solution Overview
Problem
Existing positive displacement pumps face challenges in minimizing dead-volume and preventing damage to pressure sensors due to the movement of the pump piston, which affects measurement accuracy in pipetting and dispensing devices.
Innovation Solution
The introduction of a piston sleeve integrated into the cylinder wall, which extends over the entire length of the pump cylinder, creates a pressure channel that minimizes the volume where pressure differs, allowing the pump piston to move without compromising the pressure sensor, thus reducing dead-volume and ensuring accurate pressure measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the pressure sensor is fluidly connected to the cylinder space through a pressure channel, then the pressure measurement is enabled, but the dead-volume increases and the pressure sensor may be damaged by the pump piston movement
Solution Approach 1:
The pressure channel is segmented into two distinct portions: a first portion extending from the cylinder space to the pressure sensor, and a second portion extending from the pressure sensor to the outlet. This segmentation allows the pressure sensor to be positioned away from the high-pressure zone near the piston while maintaining fluidic connection, thereby reducing dead-volume and preventing piston damage to the sensor.
Solution Approach 2:
The pressure channel is configured to extend the pressure sensing path in the longitudinal direction away from the piston, utilizing the longitudinal dimension of the cylinder to route the pressure channel through the piston or along the cylinder wall, thus separating the sensor from the dangerous zone while maintaining pressure measurement capability.
2Volume of stationary object
If the pressure sensor is positioned close to the cylinder outlet, then the dead-volume is reduced, but the pressure sensor may be damaged by the pump piston when it moves past the sensor position
Solution Approach 1:
The outlet acts as an intermediary element between the pressure sensor and the pump piston. The pressure channel is configured to extend through or near the outlet, allowing the outlet structure to shield the pressure sensor from direct contact with the piston while maintaining pressure measurement functionality.
3Reliability
If the pressure channel is configured to extend through the outlet, then the pressure sensor is protected from piston damage, but the device complexity increases
Solution Approach 1:
The outlet is designed to serve multiple functions: it acts as the fluid discharge pathway and simultaneously serves as a protective structure for the pressure sensor by routing the pressure channel through or near it. This multi-functionality reduces the need for additional protective components, thereby limiting the increase in device complexity.
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 design minimizes dead-volume and prevents damage to the pressure sensor, enhancing measurement accuracy and reliability in liquid handling applications by ensuring the pump piston can move freely without interfering with the pressure sensor, thereby improving the overall performance of the positive displacement pump.
Implementation Method 1
a pressure sensor (10) that is located in or outside of an orifice (11) in the cylinder wall (4) for detecting the pressure in the cylinder space (9)
Data Source
Figure 1A~3B
Figure 4A~4E
Figure 5A~5C
AI summary
A positive displacement pump (1) is equipped with a pump cylinder (2), a pump piston (7), a cylinder space (9), a pressure sensor (10), and a pressure channel (12). A main portion (13) of the pressure channel (12) extends parallel to a longitudinal axis (3) of the pump cylinder (2), for providing fluidic connection between the cylinder space (9) and the pressure sensor (10). In the improved alternative positive displacement pump (1), the cylinder wall (4) comprises a piston sleeve (14) that is located on the inner side of the cylinder wall (4) and that extends over essentially the entire length of the pump cylinder (2) to the cylinder bottom (5). The improved alternative positive displacement pump (1) is further characterized in that, the main portion (13) of the pressure channel (12) is located in the cylinder wall (4) comprising the piston sleeve (14), which is thus preventing the pump piston (7) from touching or compromising the pressure sensor (10) or an inner surface (30) of the cylinder wall (4) when moving past the position of the pressure sensor (10). Also disclosed are a liquid handling robot that comprises a single or multiple arrangement of the positive displacement pump (1) and liquid handling workstation that comprises such a liquid handling robot.