Bistable Electromechanical Actuator with Spring-Permanent Magnet Balance
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Solution Overview
Problem
Reversing solenoids have low electrical efficiency, limited dynamics, and high dead times, making them costly and inefficient in applications like medium-voltage switching devices and automotive systems, and they often require complex end position damping to prevent wear.
Innovation Solution
A drive design featuring an armature, soft-magnetic frame, and permanent magnets with a spring system that reduces reluctance and allows for high force generation, enabling efficient energy use and fast positioning, with the armature and frame arranged to allow partial immersion and inhomogeneous magnetic flux, and using a connecting rod for rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional reversing solenoids are used, then they can maintain a state against restoring force without power consumption, but they exhibit low electrical efficiency leading to high costs and thermal destruction at higher switching frequencies
Solution Approach 1:
The patent changes the fundamental operating parameters by introducing permanent magnets to create a bistable system where the armature can maintain positions without continuous power supply. The magnetic circuit parameters are optimized to reduce reluctance and improve flux distribution, enabling efficient operation at higher switching frequencies without thermal destruction.
Solution Approach 2:
The invention employs composite magnetic circuits combining soft magnetic materials and permanent magnets. This composite approach creates a hybrid system that leverages the advantages of both material types: soft magnetic materials for controllable flux paths and permanent magnets for stable state maintenance without continuous power consumption.
2Speed
If conventional reversing magnets are used, then they can provide force against restoring force, but they exhibit low dynamics with long dead times especially in long-stroke drives
Solution Approach 1:
The patent implements dynamic optimization by designing the magnetic circuit to provide high initial force at the start of stroke. The inhomogeneous flux distribution ensures maximum force availability when needed, reducing dead times. The geometric design of armature and frame allows rapid response while accommodating long stroke requirements.
Solution Approach 2:
The invention applies local quality optimization by creating inhomogeneous magnetic flux density distribution within the magnetic circuit. The flux density is specifically engineered to be highest where most needed during stroke initiation, providing localized force enhancement that improves overall dynamics without compromising long-stroke capability.
3Loss of energy
If bistable reversing magnets are used, then they can maintain positions without power, but they exhibit highest armature speed at end position leading to high wear and requiring expensive damping
Solution Approach 1:
The patent applies beforehand cushioning by designing the magnetic circuit to generate holding forces that naturally dampen armature motion before it reaches end positions. The inhomogeneous flux distribution creates progressive force reduction as the armature approaches its destination, cushioning the impact and reducing wear without requiring additional damping mechanisms.
Solution Approach 2:
The invention changes the force characteristic parameters throughout the stroke by optimizing the magnetic circuit geometry. The reluctance and flux density are engineered to vary position-dependent, providing strong holding forces during positioning while automatically reducing forces near end positions to prevent impact and wear.
4Ease of operation
If conventional reversing solenoids are used, then they can actuate valves and switches, but they require complex end position damping to prevent wear and limit service life
Solution Approach 1:
The patent implements self-service by designing the magnetic circuit to inherently provide end-position damping through its geometric and magnetic properties. The system serves itself by using the same permanent magnets and magnetic circuit that provide actuation force to also provide cushioning and wear protection, eliminating the need for separate damping components.
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 design achieves higher electrical efficiency, reduced dead times, and increased force generation with a compact structure, allowing for higher switching frequencies and lower wear, while maintaining stability without power.
Implementation Method 1
the magnetic flux generated by energizing the coil(s) at least partially passes through the permanent magnet(s), so that a force acts on the permanent magnet(s) which is transmitted to the armature
Implementation Method 2
the magnetic flux density generated by the coil(s) and felt by the permanent magnet(s) has a gradient perpendicular to the polarization direction of the permanent magnet(s)
Implementation Method 3
the armature is designed such that its increasing immersion in the frame during a stroke reduces the reluctance of the magnetic circuit
Data Source
Figure 1
AI summary
The invention relates to a permanent-magnet polarized reversible lifting magnet having a first and a second end-of-stroke position, and having at least one armature, characterized in that the magnet has or is operated by means of a spring system, which in each of the two end-of-stroke positions exerts a force on the armature, or armatures, in the direction of the stroke center position. According to the invention, the spring system and the reversible lifting magnet are balanced such that in both end-of-stroke positions, the armature, or the armatures, can be held permanent-magnetically against the spring force. Preferably, the spring system is to be configured such that the potential energy (elastically) stored therein due to moving the armature, or armatures, into the end-of-stroke position(s) of the armature(s) is as equal as possible in both end-of-stroke positions. If external restoring forces are present as a result of the application, the external restoring forces need to be taken into account accordingly in the configuration of the spring system.