Electromagnetic Actuator Same Polarity Magnet Arrangement
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Solution Overview
Problem
The challenge is to create an electromagnetic actuator for surgical or medical instruments, such as endoscopes, that can be switched reliably despite the stringent space constraints and high demands on accuracy and precision, where slight variations in permanent magnet dimensions can affect the magnetic field and focusing ability of the lens.
Innovation Solution
The actuator employs permanent magnets with the same polarity arranged around the sliding tube to minimize the impact of dimensioning variations, and coils with opposite winding directions to ensure stable rotor positioning, along with diodes for efficient electrical line management and a cylindrical yoke to enhance magnetic field concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the permanent magnets are arranged with opposite polarity to generate strong magnetic fields for reliable rotor switching, then the magnetic field strength is improved, but manufacturing precision requirements increase because slight variations in magnet dimensions negatively affect the field lines and switching behavior
Solution Approach 1:
Instead of arranging permanent magnets with opposite polarity (north facing south) to create strong magnetic fields, the patent inverts this approach by arranging magnets with the same polarity (north facing north, south facing south). This inversion creates a magnetic field configuration where the fields of adjacent magnets partially cancel each other, resulting in a more uniform and stable magnetic field that is less sensitive to dimensional variations in the magnets, thereby maintaining reliable switching behavior despite manufacturing tolerances.
2Volume of moving object
If the actuator components are miniaturized to fit within the limited space of the endoscope shaft, then the space utilization is improved, but the accuracy requirements for coils and rotor arrangement increase
Solution Approach 1:
The patent changes the magnetic field configuration parameter by using permanent magnets with the same polarity arrangement instead of opposite polarity. This parameter change creates a more tolerant magnetic field environment that allows for reliable actuator operation with reduced precision requirements for coil and rotor arrangement, enabling miniaturization while maintaining functional accuracy within the constrained endoscope shaft space.
3Ease of manufacture
If the permanent magnets are made slightly larger or smaller due to production variations, then manufacturing ease is improved, but the end positions of the slider become unstable and the lens can no longer be properly focused
Solution Approach 1:
The patent inverts the conventional magnet arrangement by using the same polarity for adjacent permanent magnets instead of opposite polarity. This inversion creates a magnetic field configuration where field interactions are less sensitive to magnet size variations. The resulting uniform field distribution ensures that slight production variations in magnet dimensions do not significantly affect the magnetic field strength or the stability of the slider's end positions, maintaining reliable focusing capability.
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 configuration allows for a more reliable and stable switching of the actuator, reducing the effect of manufacturing deviations in magnet dimensions and enabling precise focusing of the lens within the limited space of the endoscope shaft.
Implementation Method 1
the two magnetic fields are at least partially superimposed and thus interact
Implementation Method 2
The stator has at least two ring-like, axially magnetized permanent magnets
Implementation Method 3
By energizing the coils, the rotor is moved from one end position to the other end position by the induced magnetic field of the coils
Implementation Method 4
each coil is preceded by a diode which is oriented differently, so that the conduction directions of the diodes are reversed with respect to the coils
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
Electromagnetic actuators (10) are used, for example, to focus a lens in an endoscope (10). Actuators (10) of the type in question are very small. Even very small, production-caused variations in the dimensioning of the permanent magnets (20, 21) of the actuator (10) have a negative effect on the field line pattern of the magnets (20, 21) and therefore on the switching behavior of the actuator (10). The invention relates to an actuator (10) that can be switched particularly reliably. This is achieved in that the permanent magnets (20, 21) are arranged in such a way that a magnetic south pole (25) of the one permanent magnet (20, 21) faces a magnetic north pole (24) of the other permanent magnet (20, 21).