Metering Pump Air Detection via Position Monitoring
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Solution Overview
Problem
Existing methods for venting delivery units for liquid additives in the motor vehicle sector face challenges with air accumulation, leading to reduced delivery capacity and uncertainty in additive delivery, resulting in potential disruptions to exhaust gas treatment processes.
Innovation Solution
A method involving a metering pump with a movable pump element and a delivery line, where pressure is built up, a test pressure is determined, and the pump element position is monitored to detect air, initiating a flushing process if air is present, ensuring precise delivery and maintaining operational integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a vent valve is opened to remove air from the line system, then air is flushed out of the delivery unit, but the pressure in the line system drops and precise delivery of liquid additive cannot take place
Solution Approach 1:
The patent detects air in the delivery line before it significantly impacts delivery precision by monitoring pump element position against a limit position. The flushing process is initiated proactively when air is detected, rather than waiting for delivery problems to occur, allowing air removal while maintaining pressure control.
Solution Approach 2:
The control device continuously monitors the pump element position and compares it to a predetermined limit position to detect air presence. This feedback mechanism allows the system to automatically initiate flushing when needed and restore normal operation when air is removed, maintaining delivery precision throughout the process.
2Measurement precision
If the pump element position is monitored to detect air, then conveying accuracy is enhanced, but the system complexity increases
Solution Approach 1:
The system uses existing pump components (the pump element and its position indicators) to detect air presence. The pump element's own position serves as the detection mechanism, eliminating the need for separate sensors or complex detection systems. The control device simply monitors whether the pump element reaches its normal position, which is information already available from the pump's operation.
3Productivity
If a flushing process is initiated to remove air, then delivery capacity is restored, but time is lost during the flushing operation
Solution Approach 1:
The flushing process is executed as a brief, intensive operation rather than a prolonged gradual process. The control device opens the vent valve and activates the pump specifically for flushing, then quickly closes the valve and resumes normal operation once air is detected to be removed. This minimizes the time lost to flushing while effectively restoring delivery capacity.
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 method reliably detects air in the delivery unit without pressure drops, enhancing conveying accuracy and allowing uninterrupted dosing, thus preventing disruptions to exhaust gas treatment processes.
Implementation Method 1
the pump element changes the volume of the pump chamber between a minimum pump chamber volume and a maximum pump chamber volume. Two pump valves are adjoined to the pump chamber, by means of which liquid additive can be drawn into the pump chamber during an intake phase of the pump and pushed out of the pump chamber during a delivery phase of the pump
Data Source
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Figure 3~4
Figure 5
AI summary
The method involves determining whether a predetermined test pressure in a delivery line (4) is reached. A position of a movable pumping element is determined when the test pressure is reached. The determined pumping element position is compared with a predetermined limit position such that air (7) in the delivery line is determined when the pumping element position exceeds the predetermined limit position. A rinsing procedure is initiated for a part of the delivery line when the air in the delivery line is determined. Independent claims are also included for the following: (1) a supply unit for a liquid additive (2) a motor vehicle.