Pneumatic Stepper Motor with Offset Teeth for MRI-Safe Positioning
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Solution Overview
Problem
Conventional stepper motors using electromagnetic forces are unsuitable for environments with strong magnetic fields, such as MRI scanners, and hazardous chemical plants due to interference and safety concerns, as they can malfunction or cause sparks.
Innovation Solution
A stepper motor design utilizing cylindrical translators with triangular asymmetric teeth that rotate via pressurized gas or fluid, allowing the rotor to rotate without translating axially, eliminating the need for electromagnetic forces and ensuring safety in sensitive or hazardous environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electromagnetic forces are used to drive the stepper motor, then the motor can achieve reliable rotation and positioning, but the motor cannot be used in environments with strong magnetic fields (such as MRI scanners) or hazardous chemical plants due to interference and safety concerns
Solution Approach 1:
The patent replaces the electromagnetic driving system with a purely mechanical pneumatic system. Compressed gas acts on diaphragms to create mechanical motion that is transmitted through gears and shafts to rotate the rotor, eliminating all electromagnetic components and making the motor safe for use in MRI scanners and hazardous environments
Solution Approach 2:
The motor uses compressed gas (pneumatics) as the driving medium. Gas pressure acts on flexible diaphragms to generate mechanical force, which is then transmitted through a train of gears and shafts to produce controlled rotation of the rotor, providing a safe alternative to electromagnetic actuation in sensitive environments
2Measurement precision
If electromagnetic coils are used in the stepper motor, then precise control and positioning can be achieved, but sparks may be generated that can lead to dangerous situations in chemical plants with highly flammable gases or liquids
Solution Approach 1:
The patent eliminates electromagnetic coils and replaces them with a mechanical pneumatic actuation system using diaphragms, gears, and shafts, thereby removing the source of sparks while maintaining precise positioning control through mechanical feedback and controlled gas pressure
3Measurement precision
If strong magnetic fields are applied during MRI scanning, then detailed imaging can be obtained, but electromagnetic stepper motors will malfunction or interfere with the scanning process
Solution Approach 1:
The patent replaces electromagnetic motor components with a mechanical pneumatic system that uses compressed gas to actuate diaphragms and drive the rotor through mechanical linkages, eliminating electromagnetic interference with MRI scanners while maintaining precise positioning capability
Solution Approach 2:
The motor uses compressed inert gas (such as nitrogen or filtered air) as the driving medium, creating an electromagnetically inert environment that does not interfere with MRI scanning while still providing the mechanical force needed for precise rotor positioning
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
Enables reliable and safe operation of stepper motors in MRI scanners and chemical plants by using a non-ferromagnetic material and pressurized gas to rotate the rotor, minimizing interference and preventing sparks, thus maintaining system integrity and safety.
Implementation Method 1
The translators can be moved by a pressure difference between the part of the cylindrical space between the housing of the one or the other of the translators and the part of the cylindrical space between that translator and the rotor
Implementation Method 2
the translator then exerts a normal axial force and a rotational tangential force on the rotor so that the rotor rotates until the teeth on both surfaces fit into each-other, i.e. interlock
Data Source
AI summary
Stepper motor with a housing 1,2,4,6,16, in which a cylindrical rotor 11,15 fixed on a central shaft 12 can rotate but not translate along an axial direction. There are cylindrical translators 9, 14 on both sides of the rotors 11, 15, where the translators 9, 14 are sealed fit in a cylindrical space within the housing 6 and around the central shaft 12 and where the translators 9, 14 can only translate in an axial direction, where in one axial position of a translator 9, 14 a set of triangular asymmetric teeth 20 located on the translator 9, 14 can interact and fit into a set of triangular asymmetric teeth 21 on the rotor 11, 15, where the shape of the teeth 21 on both sides of the rotor 11, 15 is symmetric and where one of the sets of teeth 20, 21 between one translator 9 (14) and the rotor 11 (15) and a set of teeth 20, 21 between the other translator 9 (14) and the rotor 11 (15) are tangentially shifted, i.e. offset over a length equal to half the width of a tooth 20, 21 and where the translators 9, 14 can be moved by a pressure difference between the part of the cylindrical space between the housing 6 and a translator 9, 14 and the part of the cylindrical space between the translator 9, 14 and the rotor 11, 15.