Magnetic Shape-Memory Pulsed Drive for Low-Vibration Actuation
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Solution Overview
Problem
Existing electric linear repetitive drives face limitations in achieving high velocities and strokes with low repetition frequencies while minimizing noise, vibrations, and heating, especially in applications like body care devices, due to their continuous-time energy output and structural constraints.
Innovation Solution
An electric linear repetitive pulsed drive utilizing a magnetic shape-memory adjustment element within a magnetic circuit, where a current pulse expands the element, and an inverse current pulse resets it back to its original position using a reset unit, allowing for discrete-time energy output and adjustable parameters to optimize performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If electromagnetic pull/push magnets or rotating motors with gearing are used to achieve high velocities, then working velocity is improved, but repetition frequency must be increased which leads to heating up, noise production, and vibrations
Solution Approach 1:
The patent employs periodic pulsed actuation of the magnetic shape-memory alloy instead of continuous operation. Each pulse generates a high-velocity stroke, followed by a rest period that allows thermal dissipation and prevents cumulative heating. This periodic on-off cycling maintains high working velocities while eliminating the continuous heat generation and associated harmful effects of traditional motors operating at high repetition frequencies
Solution Approach 2:
The patent replaces traditional electromagnetic motors and mechanical gearing systems with a magnetic shape-memory alloy actuator. This substitution eliminates the need for rotating components, bearings, and gear trains that generate friction, noise, and vibrations. The solid-state SMA actuator achieves high velocities through phase transformation without mechanical contact, thereby eliminating the harmful effects inherent in conventional mechanical drive systems
2Speed
If electric tilt armatures or flat-armature magnets are used to achieve high velocities and strokes, then working velocity and stroke are improved, but impact noise is generated when the armature impacts the stator
Solution Approach 1:
The patent replaces the mechanical impact-based reset mechanism of tilt armatures with a controlled magnetic field reversal process. Instead of allowing the armature to physically impact the stator and requiring mechanical damping, the magnetic field is reversed to actively pull the armature back to its starting position. This eliminates impact noise by substituting a controlled magnetic reset process for a violent mechanical impact
Solution Approach 2:
The patent employs a return spring that is pre-loaded to cushion the armature's return journey. The spring gradually decelerates the armature before it reaches the starting position, preventing any potential impact. This beforehand cushioning ensures that even if the magnetic field reversal is interrupted, the armature will gently contact the starting position without generating impact noise
3Object-generated harmful factors
If damping materials or springs are used to reduce impact noise, then noise production is reduced, but the stroke is limited to approximately 0.5 to 1.5 mm and velocity is drastically reduced
Solution Approach 1:
The patent replaces the passive mechanical damping approach with an active magnetic field control system. Instead of relying on damping materials that physically absorb impact energy and limit stroke, the magnetic field is actively reversed to control the armature's motion. This allows for large strokes and high velocities because the magnetic force can be precisely controlled throughout the entire range of motion without the physical constraints of damping materials
Solution Approach 2:
The patent employs dynamic control of the magnetic field strength and direction throughout the armature's stroke. The current through the coil is modulated to provide optimal force at each position, maintaining high velocity throughout the entire stroke distance. This dynamic control eliminates the need for fixed damping characteristics that would limit stroke and velocity, allowing the system to adapt in real-time to maintain optimal performance
4Duration of action of stationary object
If continuous-time energy output is used in electromagnetic drives, then continuous operation is achieved, but concentration of input energy into short time periods with high velocity is not possible
Solution Approach 1:
The patent employs periodic pulsed actuation of the magnetic shape-memory alloy instead of continuous operation. Each pulse generates a high-velocity stroke, followed by a rest period that allows the system to reset and prepare for the next pulse. This periodic on-off cycling enables concentration of energy into short time periods, achieving peak velocities that are impossible with continuous-time drives while still providing sustained operation through repeated pulses
Solution Approach 2:
The patent utilizes phase transformation in the magnetic shape-memory alloy as the operating mechanism. By changing the magnetic field parameters (strength, duration, frequency), the alloy undergoes reversible phase transformations that produce discrete high-velocity strokes. This parameter-based control allows energy to be concentrated into specific time periods for high-velocity output, rather than being distributed continuously over time as in traditional electromagnetic drives
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 solution enables higher working velocities with lower repetition frequencies, reducing noise, vibrations, and heating, while maintaining consistent energy output per pulse, thus enhancing the performance and efficiency of body care devices like shavers and toothbrushes.
Implementation Method 1
a magnetic shape-memory adjustment element that is situated in an air gap of a magnetic circuit, by said adjustment element being brought into a fast expansion by a current pulse in the coil of the magnetic circuit
Implementation Method 2
the magnetic energy, which has been stored in the ferromagnetic material of the magnetic circuit by said current pulse
Data Source
AI summary
An electric linear repetitive pulsed drive for an operation of apparatuses, in particular for an operation of apparatuses for improving an efficiency of which a working energy that is output in a pulsed manner, with at the same time low repetition frequencies, is advantageous, includes a magnetic circuit with an air gap and an electric coil, a magnetic shape-memory adjustment element and a reset unit, and a control electronics unit, wherein the electric linear repetitive pulsed drive outputs its energy in discrete-time fashion, bundled in short time intervals, that is in pulses.