Double Rotor Stepper Motor for High Angular Resolution
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Solution Overview
Problem
Stepper motors used in aerospace applications face challenges in achieving high angular resolution while maintaining a simple mechanical design, limited size, and the ability to hold position without power consumption, as finer resolutions often require mechanical reducers that increase weight, size, and energy inefficiency, or more complex electronics that lose holding torque when powered off.
Innovation Solution
A double-rotor stepper motor design with differential movement, featuring a stator and two rotors with teeth distributed according to specific pitches, allowing for precise alignment and magnetic field circulation to achieve small angular movements between supply phases without the need for mechanical reducers or constant power supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a mechanical reducer is added to achieve finer angular resolution, then angular resolution is improved, but weight and size increase
Solution Approach 1:
The rotor is segmented into two independent rotors (first rotor with teeth of pitch p1, second rotor with teeth of pitch p2) that can move differentially relative to each other and the stator. This segmentation allows each rotor to contribute to angular resolution independently, achieving fine resolution without requiring a mechanical reducer that would increase weight.
2Measurement precision
If a mechanical reducer is added to achieve finer angular resolution, then angular resolution is improved, but device complexity increases
Solution Approach 1:
The patent merges the functions of multiple rotors and differential movement into a single integrated motor structure. The two rotors with different tooth pitches work together with the stator to achieve fine angular resolution through electromagnetic interaction alone, eliminating the need for separate mechanical reducer components and simplifying the overall mechanical design.
3Measurement precision
If microstep control is used to achieve finer angular resolution, then angular resolution is improved, but holding torque is lost when power is off
Solution Approach 1:
The patent employs dynamic control of the two rotors through independent electromagnetic actuation. By controlling the relative positions of the two rotors with respect to the stator through electromagnetic fields alone (without mechanical reducers), the system achieves fine angular resolution while maintaining the inherent holding torque capability of stepper motors when power is applied.
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 precise control in full step mode with minimal angular movement between supply phases, reducing size, weight, and energy consumption while maintaining holding torque without power, thus addressing the limitations of existing stepper motors.
Implementation Method 1
the N stator pads comprising a plurality a of teeth distributed according to the pitch p1, the N stator pads being distributed over the stator according to a third pitch equal to p1(a+1/N)... the teeth of the first set being capable of coming into alignment individually with one of the stator studs
Implementation Method 2
allowing for precise alignment and magnetic field circulation to achieve small angular movements between supply phases
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The double rotor stepping motor (30) has stator (31) having stator contacts, first rotor (32) having first set of teeth distributed at first pitch, and second set of teeth distributed at second pitch, and second rotor (33) having rotor contacts. The stator contacts are distributed at third pitch. The rotor contacts are distributed on second rotor at fourth pitch, and are aligned with teeth of second set, such that passage from one alignment to consecutive alignment causes second rotor to move in direction opposite movement of first rotor with respect to first rotor by predetermined pitch.