Free Floating Weighing Pan Scale Using Electromagnetic Compensation
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Solution Overview
Problem
Conventional magnetic force compensation scales face inaccuracies due to additional forces in the direction of gravity, corner load forces, and sensitivity to heat, while electromagnetic force compensation systems are imprecise and bulky, limiting their suitability for high-resolution weighing.
Innovation Solution
A scale with a freely floating pan uses at least six position sensors and electromagnetic mechanisms with permanent magnets and plunger coils to generate compensating forces in six degrees of freedom, maintaining the pan's position and calculating the weighing result based on current magnitudes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional magnetic force compensation balances use linkages and flexural joints to transfer force, then the weighing mechanism can be constructed, but additional forces are generated that distort the weighing signal and reduce measurement precision
Solution Approach 1:
The patent extracts and removes the mechanical linkages and flexural joints from the force transfer path. Instead of using mechanical components to transfer the weighing pan's force to the load cell, the invention uses a magnetic field to directly compensate for gravitational force, eliminating the source of additional harmful forces that distort measurements
Solution Approach 2:
The patent replaces the mechanical force transfer system (linkages, joints, levers) with an electromagnetic field-based compensation system. The magnetic field generated by the moving coil and permanent magnet directly counteracts gravitational force on the weighing pan, substituting mechanical transmission with electromagnetic interaction to eliminate mechanical errors
2Measurement precision
If the balance is adjusted to align the load cell axis with gravity direction, then measurement precision improves, but the device complexity increases due to tilt adjustment mechanisms
Solution Approach 1:
The patent replaces mechanical tilt adjustment mechanisms with an electromagnetic field-based compensation system. The magnetic field can be dynamically adjusted to compensate for misalignment and corner load forces without requiring mechanical repositioning or adjustment of the load cell axis
Solution Approach 2:
The patent changes the approach from mechanically adjusting physical alignment parameters to dynamically adjusting magnetic field parameters. The moving coil current can be modified to compensate for alignment errors and corner loads, replacing mechanical parameter adjustment with electrical parameter control
3Measurement precision
If corner load forces are measured with additional sensors, then measurement precision improves, but the device complexity and cost increase
Solution Approach 1:
The patent makes the existing moving coil and magnetic field system multi-functional. The same electromagnetic mechanism that compensates for gravitational force also compensates for corner load forces and misalignment errors, eliminating the need for separate sensors while maintaining measurement precision
Solution Approach 2:
The patent enables the weighing system to self-correct for corner load forces and alignment errors using the existing electromagnetic components. The system automatically compensates for these errors through magnetic field adjustment without requiring external measurement devices or additional sensing infrastructure
4Ease of manufacture
If levers and bending joints are used in the weighing mechanism, then the structure can be constructed, but heat sensitivity increases and measurement precision deteriorates
Solution Approach 1:
The patent extracts and removes levers and bending joints from the weighing mechanism. The magnetic field-based compensation system eliminates mechanical components that are sensitive to thermal expansion and heat-induced deformation, preventing heat from affecting measurement precision
Solution Approach 2:
The patent replaces heat-sensitive mechanical components (levers, bending joints) with an electromagnetic field system that is inherently insensitive to thermal effects. The magnetic field compensation occurs without mechanical contact or transmission, eliminating thermal expansion and heat-induced measurement errors
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 allows precise weight measurement without bearing forces, reduces volume, and minimizes sensitivity to vibrations, enabling high-resolution weighing regardless of the item's volume and position.
Implementation Method 1
the weighing mechanism (4) is designed to generate compensating forces (Fc1-Fc6) on the weighing pan (3) in the six degrees of freedom by means of the currents flowing in the respective moving coils (7)
Implementation Method 2
at least six position sensors (8), wherein the at least six position sensors (8) are provided for measuring the position of the weighing pan (3) in all three dimensions
Data Source
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AI summary
Method for operating a balance (1) with a weighing pan (3), at least six position sensors (8) and a weighing mechanism (4), wherein the weighing mechanism (4) has at least six electromagnetic mechanisms (5) each with at least one permanent magnet (6) and at least one moving coil (7), and wherein the electromagnetic mechanisms (5) generate compensating forces (Fc1 - Fc6) on the weighing pan (3) in the six degrees of freedom during the weighing process through the currents flowing in the respective moving coils (7) and due to their respective orientation and position with respect to the weighing pan (3), comprising the following steps: - measuring the position of the weighing pan (3) in all three dimensions by means of the at least six position sensors (8);- Simultaneous control of the currents flowing in the respective moving coils (7) so that the compensating forces (Fc1 - Fc6) hold the weighing pan (3) in a predetermined free-floating and constant position with respect to translations and rotations in the six degrees of freedom by means of the sum of their respective torques; - Use of the magnitudes of the currents flowing in the respective moving coils (7) to calculate the weighing result.;