Ballistic Unipolar Bistable Actuator Design
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Solution Overview
Problem
Existing electromagnetic actuators with two stable positions without current either require complex and expensive bipolar power supplies or suffer from assembly challenges and mechanical instability when using unipolar power supplies.
Innovation Solution
An actuator design incorporating a ferromagnetic mobile mass, a stator with an electrically controlled wire coil, and at least two ferromagnetic poles, utilizing a permanent magnet to achieve stable positions with unidirectional magnetic flux control, allowing bidirectional movement without polarity change in the electrical supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If bipolar power supply is used to achieve two stable positions without current, then the actuator maintains stable positions without energy input, but the electronic architecture becomes more complex and expensive requiring H-bridge switching transistors
Solution Approach 1:
The patent inverts the conventional approach by using a unipolar power supply instead of bipolar, and uses a permanent magnet to provide the holding force in both stable positions rather than relying on electromagnetic coils in both positions. This inversion allows simple unipolar electronics to control bidirectional movement while maintaining bistability.
Solution Approach 2:
The permanent magnet acts as an intermediary element that enables the unipolar power supply to achieve bistable operation. The permanent magnet provides the necessary magnetic field to create two stable positions without requiring complex bipolar switching electronics, mediating between the simple unipolar supply and the bistable mechanical function.
2Device complexity
If unipolar power supply is used with mechanical elements like snap springs to achieve two stable positions, then the electronic control is simplified, but the actuator suffers from assembly challenges and mechanical instability
Solution Approach 1:
The patent replaces the mechanical snap spring system with a magnetic field-based system using a permanent magnet and ferromagnetic armature. This substitution eliminates the mechanical instability and assembly challenges of snap springs while maintaining the ability to achieve two stable positions with simple unipolar electronic control.
Solution Approach 2:
The patent changes the fundamental operating parameter from mechanical elasticity (snap springs) to magnetic field interaction (permanent magnet and ferromagnetic armature). This parameter change maintains the bistable function while improving reliability and eliminating mechanical instability issues.
3Reliability
If continuous current is supplied to keep the magnetic armature in the switched position, then the actuator maintains its position, but energy is continuously lost and heating occurs
Solution Approach 1:
The permanent magnet provides a self-sustaining magnetic field that holds the armature in stable positions without requiring continuous energy input. The system serves itself by using the permanent magnet's inherent magnetic properties to maintain position, eliminating the need for continuous current supply and associated energy losses.
Solution Approach 2:
Instead of continuous current supply, the system uses periodic or pulsed current only when switching between positions is required. The permanent magnet maintains the position during intervals between switching events, creating a periodic rather than continuous energy consumption pattern that eliminates steady-state energy loss and heating.
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 solution provides a compact, integrated, and less sensitive actuator design that maintains stable positions using a single unipolar power supply, improving assembly ease and mechanical stability while minimizing energy consumption.
Implementation Method 1
The actuator also comprises at least one permanent magnet which attracts the mobile mass in order to achieve the two stable positions
Implementation Method 2
The electrical control controls the at least one coil to generate a magnetic flux in a single direction (one way/unidirectional)
Data Source
AI summary
An actuator for controlling the movement of an element between two stable positions with pulsed electrical control without a change in polarity comprises: a ferromagnetic mobile mass, at least one electrically controlled wire coil that is fixed with respect to the mobile mass, at least two ferromagnetic poles that are fixed with respect to the mobile mass and on either side of the mobile mass. The actuator comprises at least one permanent magnet that attracts the mobile mass in order to achieve the two stable positions. The mobile mass defines, with the ferromagnetic poles, at least two variable air gaps during the movement of the mobile apparatus. The magnetic flux of the permanent magnet opposes the magnetic flux generated by the at least one coil regardless of the position of the mobile mass.