Piston Pump Leakage Compensation via Hall Sensor Feedback
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Solution Overview
Problem
Double-acting, pneumatically driven piston pumps used for conveying heated adhesives face challenges in accurately determining the volume of adhesive delivered due to leakage, which affects the precision of adhesive application and quality control, especially when dealing with small volumes and varying viscosity.
Innovation Solution
A method that measures leakage time and calculates the effectively delivered volume by determining the quotient between theoretically pumped volume and leakage time for each stroke direction, allowing for precise calculation of adhesive mass with an accuracy of ±7%, using Hall sensors to track piston position and density correction factors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If a piston pump is designed without sealing to minimize wear and maintenance, then service life is extended, but leakage occurs between piston and cylinder reducing measurement precision
Solution Approach 1:
The patent implements a feedback mechanism by measuring the actual piston position using Hall sensors and comparing it with the theoretical position. The system continuously monitors the piston rod position and uses this feedback to calculate and compensate for leakage effects, thereby maintaining measurement precision despite the intentional lack of sealing for extended service life.
Solution Approach 2:
The patent changes the operational parameters by measuring leakage time and using it to calculate correction factors. The system adjusts the volume calculation based on measured leakage parameters (leakage time, piston speed, pressure) rather than relying on fixed theoretical values, enabling accurate measurement despite variable leakage conditions.
2Productivity
If leakage is allowed between piston rod and guide for continuous operation, then productivity is maintained, but leakage volume flow increases with varying viscosity and speed
Solution Approach 1:
The system continuously monitors piston position and speed, and uses this real-time data to calculate the actual leakage volume flow. By feedback control, the system adjusts the effective volume calculation based on current operating conditions (viscosity, speed, pressure), maintaining productivity while accurately accounting for variable leakage.
Solution Approach 2:
The patent transitions from static leakage assumptions to dynamic leakage measurement. The system adapts to changing operating conditions (varying viscosity, piston speed, pressure) by continuously measuring leakage time and recalculating correction factors, enabling accurate volume determination under dynamic production conditions.
3Productivity
If check valves are used for double-acting operation to deliver adhesive in both stroke directions, then productivity increases, but flow loss occurs during reversing process at dead centers
Solution Approach 1:
The system performs preliminary measurement of leakage time during non-delivery periods (when piston moves without conveying adhesive to consumer). By measuring leakage characteristics in advance during the reversing process, the system prepares correction factors that compensate for the inevitable flow loss during dead center transitions, maintaining productivity while accounting for substance loss.
4Device complexity
If piston position is detected using only switching position sensors, then device complexity is reduced, but manufacturing precision of adhesive volume is insufficient
Solution Approach 1:
The patent replaces complex mechanical position measurement systems with magnetic field-based Hall sensors. This substitution provides continuous, high-resolution electrical measurement of piston rod position without mechanical contact, achieving superior manufacturing precision (±7% adhesive volume accuracy) while maintaining relatively simple device architecture.
Solution Approach 2:
The system transitions from discrete position detection (switching positions only) to continuous position measurement along the entire piston stroke. By measuring position as a continuous variable rather than discrete states, the system achieves higher precision in adhesive volume determination while using simple Hall sensor technology.
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
Enables precise determination of adhesive volume and mass applied per product, improving accuracy and reducing maintenance needs, with the ability to adapt to changes in temperature and pressure without recalibration, ensuring consistent quality and efficiency in adhesive application.
Implementation Method 1
In principle, the piston position can be detected by two Hall sensors
Data Source
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AI summary
The invention proposes a method for determining the volume Veff of a liquid medium, in particular a heated adhesive, effectively delivered to a consumer by a double-acting, pneumatically driven piston pump, wherein the piston pump is subject to leakage, with the following features: when a constant pressure is applied to a drive of the piston pump and at least one double stroke of the piston pump is performed from one dead center to its other dead center and back to the first dead center: a. without the piston pump being able to deliver the medium to the consumer, a leakage time tL is measured for one stroke of the piston pump from its lower dead center to its upper dead center; b. without the piston pump being able to deliver the medium to the consumer, a leakage time tL is measured for one stroke of the piston pump from its upper dead center to its lower dead center; c.For the stroke of the piston pump from bottom dead center to top dead center, a quotient is determined between the theoretically leak-free volume of the medium Vauf of the piston pump and the leakage time tL auf. For the stroke of the piston pump from top dead center to bottom dead center, a quotient is determined between the theoretically leak-free volume Vab of the piston pump and the leakage time tL ab. When pumping the medium to the consumer, the time tauf is measured for the stroke of the piston pump from bottom dead center to top dead center, and the time tab is measured for the stroke of the piston pump from top dead center to bottom dead center. The effectively pumped volume Veff is determined according to Veff = Vauf − VauftL auf × tauf + Vab − VabtL ab × tab multiplied by the number of double strokes. The invention further proposes a piston pump (3) for carrying out the method.