Membrane Pump Outlet Valve Mechanical Negative Feedback
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Solution Overview
Problem
Membrane pumps in medical technology face challenges in achieving accurate fluid metering at low flow rates, particularly for citrate anticoagulation in dialysis, where maintaining a constant fluid mass flow is crucial but difficult due to oscillation issues in membrane valve systems.
Innovation Solution
The membrane pump device incorporates a membrane valve with a valve seat arrangement that provides a 'mechanical negative feedback' mechanism, utilizing a spring-loaded ram to regulate fluid flow by varying the effective area of the membrane, preventing oscillation and ensuring consistent flow rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a membrane valve is used in the membrane pump device, then the drive unit is separated by a membrane from the fluid to be conveyed, but the system tends to oscillate and regulating properties are poor
Solution Approach 1:
The patent applies feedback by creating a mechanical negative feedback mechanism where the outward flow path includes a first outward flow channel connecting the pump chamber to the valve chamber and a second outward flow channel connecting the valve channel to the exit connection. This configuration ensures that the effective area of the membrane is varied in response to flow conditions, preventing oscillation and improving regulating properties while maintaining the separation benefit of the membrane valve.
2Measurement precision
If the cross-section area of the outlet valve seat is made smaller than the cross-section area of the region surrounding the valve seat, then mechanical negative feedback is achieved for regulating fluid flow, but the device complexity increases
Solution Approach 1:
The patent segments the outward flow path into two distinct channels: a first outward flow channel connecting the pump chamber to the valve chamber, and a second outward flow channel connecting the valve channel to the exit connection. This segmentation allows the valve seat cross-section area to be smaller than the surrounding region cross-section area, creating mechanical negative feedback for accurate fluid flow regulation while maintaining manageable device complexity through clear functional separation.
3Ease of operation
If a spring-loaded ram is used to apply pressing pressure to the membrane, then the membrane closes the valve channel in rest position, but the device complexity increases
Solution Approach 1:
The patent implements self-service by using a spring-loaded ram that automatically applies pressing pressure to the membrane to close the valve channel in the rest position. The spring mechanism provides automatic resetting and maintains the closed state without requiring external control, simplifying operation while the integrated design keeps the overall device complexity manageable.
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 configuration enhances the regulating properties of the membrane pump, preventing oscillation and ensuring accurate, constant fluid mass flow even at low flow rates, thereby improving the precision of fluid metering in medical applications such as dialysis.
Implementation Method 1
the membrane sits on the valve seat so that the outlet valve is closed
Implementation Method 2
the system tends to oscillate. A prerequisite of the invention is that in the rest position a pressing pressure is applied to the membrane of the outlet valve by an actuating device so that the membrane closes the valve channel. For example, the pressure can be applied by a spring-loaded ram.
Implementation Method 3
the outward flow path comprises a first outward flow channel which connects the outlet opening of the pump chamber to an inlet opening of the valve chamber of the outlet valve, and comprises a second outward flow channel which connects the outlet valve channel to the exit connection, wherein the cross-section area of the outlet valve seat is smaller than the cross-section area of the region of the outlet valve chamber surrounding the outlet valve seat. This arrangement effects a 'mechanical negative feedback'
Data Source
AI summary
The invention relates to a membrane pump device 2 for conveying fluids, in particular medical liquids for blood treatment. The invention furthermore relates to a membrane pump with a membrane pump device 2 and an actuating device 1 for the membrane pump device 2. The membrane pump device 2 has a pump chamber body 253 in which a recess, which is closed by an elastic membrane 201 to form a pump chamber 252, is constructed. The membrane pump device 2 moreover comprises an inward flow path 219 which connects an entry connection 204 to an inlet opening 215 of the pump chamber 252, and an outward flow path 223 which connects an outlet opening 216 of the pump chamber 252 to an exit connection 205. An inlet valve 202 is provided in the inward flow path 219 and an outlet valve 203 is provided in the outward flow path 223. The outlet valve 203 is a membrane valve which has a valve body 254A in which a recess is constructed which is closed by an elastic membrane 201 to form a valve chamber 218 in which a valve seat 225 is arranged, the front face of which faces the membrane and in the open position of the outlet valve is arranged at a distance from the valve seat, wherein a valve channel 240 passes through the valve seat. The outward flow path 223 comprises a first outward flow channel 214 which connects the outlet opening 216 of the pump chamber 252 to the outlet valve chamber 218, and a second outward flow channel 214A which connects the outlet valve chamber 240 to the exit connection 205, wherein the cross-section area of the outlet valve channel 240 is smaller than the cross-section area of the region of the valve chamber 218 surrounding the outlet valve seat 225.