Load-Cell Gravimetric Refilling Control for Bulk Material Dosing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Gravimetric metered dispensing units face challenges during refilling, as they become blind to mass flow changes due to weight disturbances, leading to uncontrollable mass flow and significant dispensing errors, especially when bulk materials are compacted or experience fluidization, which can result in quality issues in pharmaceuticals and color mixing applications.
Innovation Solution
A metered dispensing unit with a controller that uses load cells to measure the weight of bulk material during refilling, compensates for disturbances by calculating the actual mass flow from the difference in weight, and applies a correction factor to the volumetric control model to maintain target mass flow, even during refilling, using sensors to account for momentum, pressure, and compaction effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If gravimetric control is used during refilling, then measurement precision is improved, but device complexity increases due to additional sensors and compensation mechanisms
Solution Approach 1:
The patent introduces an intermediary calculation method that uses the relationship between refilling weight and discharged weight to determine actual mass flow during refilling. Instead of directly measuring mass flow during refilling, the system uses load cell weight measurements as intermediaries to calculate the actual mass flow through mathematical relationships, thereby achieving precise measurement without requiring complex direct flow sensors during the refilling phase.
Solution Approach 2:
The patent replaces mechanical direct flow measurement systems with a computational approach using load cell weight measurements and mathematical calculations. By substituting complex mechanical flow sensors with simpler weight-based calculations, the system achieves precise mass flow measurement during refilling while reducing overall device complexity.
2Device complexity
If volumetric control is used during refilling, then device complexity is reduced, but manufacturing precision deteriorates due to unaccounted compaction and fluidization
Solution Approach 1:
The patent implements feedback by continuously monitoring load cell weight measurements during refilling and using this information to calculate actual mass flow. The system compares the calculated actual mass flow with the target mass flow and adjusts the volumetric control parameters accordingly, thereby compensating for compaction and fluidization effects and maintaining manufacturing precision without requiring complex direct flow measurement systems.
Solution Approach 2:
The patent changes the control parameter from direct volumetric measurement to weight-based calculation. By using load cell weight measurements as the primary parameter and calculating mass flow through mathematical relationships, the system adapts to varying material properties during refilling, compensating for compaction and fluidization effects while maintaining simplicity in the control system.
3Productivity
If refilling is performed during metered dispensing, then productivity is improved, but measurement precision deteriorates due to weight disturbances from bulk material momentum
Solution Approach 1:
The patent applies preliminary action by detecting the start of refilling through load cell weight changes before the bulk material flow significantly disturbs the measurement. The system proactively switches to the alternative calculation method in advance, using the relationship between refilling weight and discharged weight to determine actual mass flow, thereby avoiding measurement errors before they occur and maintaining continuous productive operation.
Solution Approach 2:
The patent implements dynamic control by continuously monitoring load cell weight measurements and automatically switching between different calculation methods based on the operational state. The system dynamically adjusts its measurement approach between normal gravimetric control and the alternative refilling calculation method, maintaining measurement precision throughout the entire refilling and dispensing cycle without interrupting 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 solution enables precise control of mass flow during refilling, minimizing dispensing errors and ensuring consistent quality by accurately determining and compensating for disturbances, thereby maintaining target mass flow and reducing errors in pharmaceutical and color mixing applications.
Implementation Method 1
The metered dispensing unit is positioned on a load cell, so that the weight registered by the load cell is the gross weight, i.e. the known and constant weight of the components of the metered dispensing unit (tare) plus the variable weight of the bulk material currently present in the storage hopper (net weight)
Implementation Method 2
A refilling station then fills the hopper with bulk material as soon as a predetermined lower fill level is detected in it by gravimetric means
Data Source
AI summary
The method according to the invention provides a way to continue gravimetric weighing of bulk material during refilling of a gravimetric metered dispensing unit, and to determine the mass of the refilled bulk material using a refilling container during the filling operation material and so determine the actual mass flow discharged during refilling in real time or on average in order to adjust it to a target mass flow.