Constant-Force Transducer Using Repulsive Magnetic Weight Compensation
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Solution Overview
Problem
Existing constant force transmitters based on attractive magnetic forces are limited by the directionality of the force, requiring the rotor to protrude through the stator, which increases installation space requirements and limits the maximum force and stroke, while also being inefficient in counteracting weight forces in linear drive systems.
Innovation Solution
A constant force transmitter utilizing a tubular design with a stator and rotor having permanent magnetic regions magnetized perpendicular to the longitudinal axis, generating a repulsive net force component that counteracts weight forces, allowing for a more compact design and increased force and stroke capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If an attractive magnetic force constant force sensor is used, then the weight force can be compensated, but the rotor must protrude through the stator which increases installation space requirements
Solution Approach 1:
The patent inverts the conventional attractive magnetic force approach by using repulsive magnetic force between like poles. The rotor and stator are both magnetized in the same direction, creating repulsion that pushes the rotor away from the stator, enabling force transmission without the rotor protruding through the stator, thus reducing installation space requirements
Solution Approach 2:
The patent changes the magnetization direction from perpendicular to the longitudinal axis (conventional) to parallel with the longitudinal axis (new dimension). This dimensional change in magnetization orientation enables the repulsive force mechanism that eliminates the need for rotor protrusion, solving the space constraint problem
2Force
If an attractive magnetic force constant force sensor is used, then the weight force can be compensated, but the maximum force and stroke are limited
Solution Approach 1:
By inverting from attraction to repulsion, the patent enables both rotor and stator to be magnetized in the same direction along the longitudinal axis. This configuration allows the magnetic fields to interact over a longer distance without requiring the rotor to protrude, thereby increasing both the maximum force capability and the stroke length
3Force
If a linear motor is continuously energized to counteract weight, then the mass can be kept at rest, but additional electrical power is required causing losses
Solution Approach 1:
The constant force sensor uses permanent magnets that generate magnetic fields without requiring external power supply. The repulsive magnetic force between the magnetized rotor and stator automatically compensates for weight forces, eliminating the need for continuous electrical power consumption and associated losses
Solution Approach 2:
The patent replaces the electromechanical linear motor system with a passive magnetic field-based constant force sensor. This substitution eliminates electrical power requirements by using permanent magnetic fields to generate the necessary repulsive force for weight compensation
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 repulsive constant net force component enables efficient counteraction of weight forces without the need for continuous electrical power, reducing mechanical loads and enhancing the design flexibility and performance of linear drive systems.
Implementation Method 1
The permanent magnetic stator region and at least partially also the permanently magnetic rotor region are each magnetized in a magnetization direction that is perpendicular to the direction of the longitudinal axis... the first sub-region which has a magnetization which has a net magnetization component in a direction opposite to the magnetization direction of the permanent-magnetic stator region
Implementation Method 2
a magnetic force acting between the permanent magnetic stator region and the permanently magnetic rotor region has a constant net force component in the direction of the longitudinal axis
Data Source
Figure 1~3
Figure 4~6
Figure 7~9
AI summary
A constant force encoder comprises: - a stator (2) having a longitudinal axis (22) and a permanent magnet stator section (20); and - a rotor (1) arranged to be movable relative to the stator in the direction of the longitudinal axis, which has a permanent magnet rotor section (7). The permanent magnet stator section (20) and the permanent magnet rotor section (7) are each magnetized in a magnetization direction perpendicular to the direction of the longitudinal axis (22). The permanent magnet stator section (20) and the permanent magnet rotor section (7) are arranged only partially overlapping in the direction of the longitudinal axis, such that a magnetic force acting between the permanent magnet stator section (20) and the permanent magnet rotor section (7) has a net force component in the direction of the longitudinal axis (22).The permanent magnet rotor area (7) has a first sub-area (71) which has a magnetization having a net magnetization component in a direction (30) opposite to the magnetization direction (31) of the permanent magnet stator area (20), so that in the case of a only partially overlapping arrangement of the first sub-area (71) and the permanent magnet stator area (20) the net force component includes a repulsive net force component (50) which repels the rotor away from the stator (2) in the direction of the longitudinal axis (22).