Sensorless Metering Pump Control via Motor Electrical Parameters
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Solution Overview
Problem
Existing metering pumps require position sensors for precise control, which can be cumbersome and prone to dosing errors due to calibration issues, especially under varying working pressures, and do not effectively detect wear or blockages without complex mechanisms.
Innovation Solution
A method that calculates and compares actual motor torque and magnetic flux with predetermined reference values to adjust motor speed and voltage, allowing for precise control without a position sensor, enabling detection of wear and blockages, and maintaining accurate dosing across a range of pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a position sensor is used to scan the reference element for precise control of the displacement member, then dosing accuracy can be improved, but the device complexity increases and calibration issues arise under varying working pressures
Solution Approach 1:
The patent replaces the mechanical position sensor system with an electrical measurement system. Instead of using a position sensor to physically scan the reference element, the invention measures electrical parameters (current, voltage, frequency) of the drive motor and calculates displacement member position from these electrical characteristics, thereby eliminating the position sensor and reducing device complexity while maintaining dosing accuracy
Solution Approach 2:
The drive motor serves dual functions: it both drives the displacement member and provides the measurement signal for position detection. The motor's electrical parameters inherently contain information about the displacement member's position, eliminating the need for separate measurement devices. The system uses the motor's own operational characteristics for self-monitoring and control
2Measurement precision
If calibration measurements are performed to account for diaphragm deformation under working pressure, then dosing accuracy improves within a pressure range, but the process becomes time-consuming and recalibration is needed when pressure changes
Solution Approach 1:
The system continuously monitors the drive motor's electrical parameters during operation and uses this real-time feedback to dynamically adjust control signals. By measuring current, voltage, and frequency throughout the stroke cycle, the system automatically compensates for pressure-induced deformations without requiring manual calibration, eliminating calibration time while maintaining accuracy across varying pressures
Solution Approach 2:
The patent transitions from static calibration (fixed pressure range) to dynamic compensation (real-time adjustment). The control system continuously adapts to changing working conditions by processing electrical measurements during each stroke cycle, allowing the pump to maintain dosing accuracy across a wide pressure range without recalibration
3Productivity
If the drive motor is switched on continuously for continuous dosing, then productivity increases, but energy consumption increases and start-up/braking times must be considered for individual strokes
Solution Approach 1:
The patent employs periodic switching of the drive motor on and off, synchronized with the dosing requirements. By precisely controlling the motor's operation cycles based on real-time position feedback from electrical measurements, the system achieves continuous dosing output while minimizing motor runtime, thereby reducing energy consumption without sacrificing productivity
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 approach enhances dosing accuracy and reliability by eliminating the need for position sensors, allowing for real-time adjustment of motor parameters to maintain consistent dosing volume and detect potential issues like wear and blockages, ensuring precise control and reduced errors across varying pressures.
Implementation Method 1
a drive motor with a shaft driven by the motor
Implementation Method 2
the generally continuous rotary motion of a drive motor is converted by a gear unit into an oscillating motion of the displacement member
Implementation Method 3
These dosing pumps work according to the volumetric principle, i. That is, the dosing process is carried out by displacing a closed chamber volume with the aid of a displacement element
Data Source
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Figure 3a
AI summary
The present invention relates to a method for controlling and/or regulating a metering pump having a drive motor having a shaft driven by the motor, and a displacement member disposed in a metering head, wherein the rotary motion of the shaft is converted into an oscillating motion of the displacement member, wherein the displacement member interacts with an outlet and inlet valve, leading to a pump stroke (pressure stroke) and an intake stroke and thus to delivering a metered medium. In order to disclose a method for controlling and/or regulating a metering pump operating principally without a position sensor on the pushrod, and that can highly precisely determine the metering behavior of the pump, according to the invention at least one motor operating parameter, preferably a motor voltage U or a motor current I, is measured, at least one control parameter is calculated from the measured motor operating parameters and optionally further known motor characteristics are calculated, the at least one control parameter is compared to a predetermined guide parameter, and a comparison signal depending on the result of the comparison is output and can be used as a status, actuating, and/or regulating signal.