Liquid Dispenser Pump Void Detection and Compensation
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Solution Overview
Problem
Existing dispensers for non-Newtonian liquids like tinting pastes face issues with high flow resistance due to viscosity changes over time, leading to vacuum voids and air entrainment, resulting in aberrant paint colors and reduced accuracy in dispensing amounts.
Innovation Solution
A method that uses controlled pump strokes and encoder measurements to detect and differentiate between vacuum and air voids, allowing for adjustments in pumping speed and operator warnings to prevent aberrant tinting, and calculates air content to compensate for entrapped air in the liquid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the pump operates at set pumping speeds to dispense tinting paste, then the dispensing speed is maintained, but vacuum voids form in the pump chamber due to high flow resistance
Solution Approach 1:
The system performs preliminary actions by detecting voids (vacuum or air) in the pump chamber before dispensing occurs. The control unit monitors piston movement during suction and pressure strokes to identify void formation early, allowing corrective actions to be taken before aberrant tinting results
2Measurement precision
If the pump chamber contains entrapped air, then the pumped amount includes air voids, but detecting and compensating for air content requires additional measurement steps
Solution Approach 1:
The system uses the existing pump mechanism and control unit to perform self-diagnosis for air content detection. The control unit monitors piston movement characteristics during normal operation to identify air voids, eliminating the need for separate external detection devices while maintaining measurement precision
3Reliability
If the viscosity of tinting paste increases over time due to pigment settlement and evaporation, then flow resistance increases, but the pump speed cannot be reduced without affecting productivity
Solution Approach 1:
The system dynamically adjusts operation based on real-time viscosity conditions. By monitoring piston movement and void formation, the control unit can optimize pump speed for current paste viscosity, maintaining dispensing accuracy while maximizing productivity. The system adapts to changing rheological properties rather than operating at fixed parameters
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 ensures accurate dispensing by identifying and addressing viscosity issues and air content, reducing the risk of aberrant paint colors and improving the reliability of the dispensing process.
Implementation Method 1
The present disclosure relates to a method for operating a liquid dispenser comprising at least one liquid container and at least one positive displacement pump
Implementation Method 2
A liquid dispenser and encoder, in particular a dispenser and encoder combination as described in EP 3 192 782 B1
Data Source
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AI summary
Liquid dispenser and method for operating such a liquid dispenser, such as a dispenser for tinting pastes. The dispenser comprises at least one liquid container and at least one reciprocating pump. First, a suction stroke is carried out at a set pump speed. After the suction stroke, the pump is closed off. Then, a pressure stroke is started while the pump is closed.