Conveyor Mass Flow Control via Gravimetric Feedback
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Solution Overview
Problem
Conventional mass flow metering systems in conveyor systems, particularly in applications like asphalt processing and agriculture, face inaccuracies due to variations in material density, belt coverage, and transport speed, leading to inaccuracies in volumetric estimates and potential obstructions like bridging, which existing technologies fail to adequately address.
Innovation Solution
A system that incorporates a load transducer to sense the total weight of material in a bin, a tachometer to measure conveyor speed, and a compensator to calculate and adjust the mass flow rate based on gravimetric measurements, intercepting and correcting volumetrically estimated mass flow rates to ensure accurate mass flow control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If volumetric mass flow estimation is used based on belt speed and fixed material density, then the system is simple to operate, but measurement precision deteriorates due to variations in material density, belt coverage, and transport speed
Solution Approach 1:
The system implements feedback by continuously monitoring actual mass flow using a load cell and comparing it with the volumetrically estimated mass flow. The compensator uses this feedback to calculate a correction factor that adjusts the tachometer output, ensuring accurate mass flow control despite variations in material properties and belt conditions.
Solution Approach 2:
The invention replaces the purely mechanical volumetric measurement system with a hybrid system that incorporates gravitational measurement through a load cell. This substitution allows direct measurement of mass flow by monitoring the weight change of the material bin, eliminating the need to rely on assumptions about material density and belt coverage.
2Measurement precision
If gravimetric mass flow measurement is implemented using a load transducer and compensator, then measurement precision improves, but device complexity increases
Solution Approach 1:
The load cell serves multiple functions: it monitors the weight of the material bin for gravimetric mass flow measurement, detects when the bin is empty to prevent damage to the belt, and provides data for calculating the correction factor. This multi-functionality reduces the need for separate dedicated components for each task.
Solution Approach 2:
The compensator acts as an intermediary device that processes signals from both the load cell and tachometer, calculates the correction factor, and adjusts the motor control signal. This intermediary component integrates the gravimetric and volumetric measurement systems without requiring complete system redesign.
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 the accuracy of mass flow metering by accounting for variations in material density and belt coverage, effectively mitigating issues like bridging and human error, thereby improving the reliability and precision of material processing systems.
Implementation Method 1
a load transducer configured to sense total weight of the bin and retained material
Implementation Method 2
a tachometer configured to produce a tachometer output reflecting conveyor speed
Data Source
AI summary
A material feed system includes a conveyor powered by a motor, a bin disposed to retain and deposit the material on the conveyor, a load transducer configured to sense total weight of the bin and retained material, a tachometer configured to produce a tachometer output reflecting conveyor speed, a motor controller configured supply the motor with a motor control command driving the motor to a volumetrically estimated mass flow rate based on the tachometer, and a compensator configured to compute a gravimetric mass flow rate based on change in total weight sensed by the load transducer. The compensator is disposed to intercept and adjust either the motor control command or the tachometer output, so as to correct for differences between the volumetrically estimated mass flow rate and the gravimetric mass flow rate.