Segmented Linear Electrical Machine for Low-Friction High-Frequency Actuation
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Solution Overview
Problem
Existing linear electrical machines used as actuators in automotive testing face limitations such as reduced peak frequencies due to inertia, potential for undesirable resonances, increased complexity and cost, and inefficiencies in power consumption and noise levels compared to servo-hydraulic systems.
Innovation Solution
A linear electrical machine (LEM) design featuring a two-section central core, fluid bearings, and a preload chamber, which reduces cantilever length, minimizes translator mass, and enhances coaxial location precision, thereby increasing specific force and operational efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single central core is used in the linear electrical machine, then the structure is simpler, but the cantilever length increases causing reduced precision in coaxial location and increased mechanical friction
Solution Approach 1:
The central core is divided into two separate sections mounted on opposite sides of the translator. This segmentation reduces the cantilever length of each core section compared to a single long core, thereby improving coaxial location precision and reducing mechanical friction while maintaining structural simplicity through symmetric design
2Force
If the translator mass is increased, then the machine can handle higher loads, but the specific force and frequency operation capability decreases
Solution Approach 1:
Traditional mechanical support structures are replaced with magnetic bearing fields generated by the stator and central core. This substitution eliminates the need for heavy mechanical support components in the translator, significantly reducing translator mass while maintaining load handling capability through electromagnetic forces, thereby improving specific force and frequency operation
3Reliability
If mechanical bearings are used for translator support, then the structure is more robust, but mechanical friction and wear increase reducing operational efficiency
Solution Approach 1:
Mechanical bearing contacts are replaced with non-contact magnetic bearing fields. The stator and central core generate magnetic fields that levitate and position the translator without physical contact, eliminating mechanical friction and wear while maintaining structural robustness through the strength of the magnetic field
4Force
If servo-hydraulic systems are used for actuation, then high force output is achieved, but the system becomes bulky and consumes excessive power
Solution Approach 1:
The servo-hydraulic system is replaced with a linear electrical machine using electromagnetic induction. The stator coils generate a moving magnetic field that directly induces current in the translator, producing high force output without the need for bulky hydraulic components, excessive power consumption, or complex fluid delivery infrastructure
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 LEM design achieves higher specific force and frequency operation with reduced mechanical friction and wear, leading to improved test subject input signal quality and increased power density, while also reducing the overall size and complexity of the machine.
Implementation Method 1
A linear electrical machine (LEM) comprises: at least one stator mounted in a housing, the housing and at least one stator defining a working cylinder; a two-section central core within the working cylinder... an exterior magnetic circuit airgap between the respective translator and stator
Implementation Method 2
The LEM design achieves higher specific force and frequency operation with reduced mechanical friction and wear
Implementation Method 3
A linear electrical machine (LEM) design featuring a two-section central core, fluid bearings, and a preload chamber
Data Source
AI summary
A linear electrical machine (LEM) comprising: at least one stator mounted in a housing, the housing and stator defining a working cylinder; a two-section central core within the working cylinder, wherein the two sections of the core are co-axial, separate and cantilever mounted within the working cylinder, a cylindrical stator bore cavity between the working cylinder and the two central core sections; and one or more hollow translators, each translator being axially movable within the stator bore cavity, such that each section of the central core is traversed by part of the one or more translators, thereby forming an exterior magnetic circuit airgap between the respective translator and stator.