Stepper Motor Torque Weighing for Precise Powder Mass Delivery
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Solution Overview
Problem
Existing weighing systems for food products, particularly milk powder, are inaccurate due to variations in granulometry, density, and rheology, leading to inconsistent mass delivery, and are either complex or unreliable, with systems like endless screws or plate-based measurements failing to account for these factors.
Innovation Solution
A weighing system using an electric stepping motor with a receiving member that applies a static torque to an output shaft, detecting precise mass by losing synchronism when a resistive torque equals the static torque, allowing for accurate and economical measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If an endless screw is used to deliver food product, then the system can continuously deliver product, but the mass delivery accuracy deteriorates due to density and granulometry variations
Solution Approach 1:
The patent replaces the mechanical endless screw delivery system with a weighing scale-based control system. Instead of relying on mechanical volumetric delivery, the system uses a weighing scale to measure the actual mass of food product delivered and adjusts the delivery process accordingly, substituting mechanical assumptions with direct mass measurement.
Solution Approach 2:
The patent implements a feedback mechanism where the actual mass of food product delivered is measured by a weighing scale and fed back to the control system. The control system then adjusts the delivery parameters based on the actual mass measured, creating a closed-loop system that compensates for density and granulometry variations.
2Measurement precision
If a plate-based weighing system is used to measure precise mass, then measurement precision improves, but device complexity and cost increase
Solution Approach 1:
The patent extracts the essential weighing function from a complex plate-based mechanical weighing system and implements it using a simpler, more direct weighing scale mechanism. This extraction allows the system to achieve precise mass measurement without the complexity of multi-component mechanical weighing apparatus.
3Productivity
If the endless screw stops, then product delivery should cease, but powder escapes and is delivered after the motor stops
Solution Approach 1:
The patent uses a weighing scale to provide real-time feedback on the actual mass of product delivered. This feedback mechanism allows the control system to precisely control the delivery timing and stop the delivery process at the exact moment the target mass is reached, preventing post-stop product escape.
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
The system provides precise and reliable measurement of food product mass, adapting to variations in granulometry and density, while being compact and cost-effective.
Implementation Method 1
the receiving member and the food product that it contains or retains, apply a static torque to the output shaft, and the electronic control unit being configured so as to apply a resistive torque, for a predetermined mass of the food product, to the output shaft so that, when the static torque is at least equal to the resistive torque, the output shaft changes position
Implementation Method 2
the value of the desired mass when reached induces a static load torque which causes loss of synchronism of the motor
Data Source
AI summary
The invention relates to a system (10) for weighing a predetermined mass of a food product, comprising an electric stepping motor (30) supported by a chassis (11) and having an output shaft, a food-product receiving member (22) which is able to move along the axis of travel between a position for receiving and a position for tipping out the food product, and an electronic control unit for controlling the electric motor. According to the invention, the receiving member is unable to move independently of the output shaft and the weighing system is configured so that, in the receiving position, the receiving member and food product apply a static torque to the output shaft, and that the electronic control unit is configured to apply a resistive torque, for a predetermined mass of the food product, to the output shaft so that when the static torque is at least equal to the resistive torque, the output shaft changes position.