Linear Electrical Machine With Fluid Bearing for High-Frequency Actuation
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Solution Overview
Problem
Existing linear electromagnetic actuators for automotive testing suffer from increased inertia due to mechanical connections and compliant members, leading to reduced peak frequencies, complexity, and increased size and cost, while servo-hydraulic systems are inefficient, noisy, and require specialized infrastructure.
Innovation Solution
A linear electrical machine (LEM) with a fluid bearing between the central core and translator, eliminating the need for additional translator length and mass, and incorporating a preload chamber to balance the test subject weight, reducing friction and system resonances, and using a labyrinth seal to maintain coaxial alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If spring and pneumatic cylinder are provided to enable static load application, then the actuator can balance test subject weight and adjust force component, but the inertia of the mechanical connection increases and peak frequency is reduced
Solution Approach 1:
The patent removes the spring and pneumatic cylinder components from the actuator system. Instead, it uses a linear electromagnetic actuator to provide both static and dynamic force components, eliminating the mechanical connections that caused increased inertia and reduced peak frequency while maintaining the ability to balance test subject weight
Solution Approach 2:
The patent replaces the mechanical spring and pneumatic cylinder system with an electromagnetic force generation system. The linear electromagnetic actuator uses electromagnetic fields to generate force, substituting mechanical compliance with electromagnetic control, thereby eliminating the inertial effects of mechanical connections while maintaining force adjustment capability
2Reliability
If translator length is increased to remain engaged with external fluid bearing, then bearing support is provided, but translator mass increases
Solution Approach 1:
The patent nests the fluid bearing system within the actuator housing rather than requiring external support. The bearing is integrated into the actuator structure, allowing the translator to remain compact while still receiving bearing support from the integrated fluid bearing system
Solution Approach 2:
The patent changes the spatial arrangement by providing bearing support in a different dimensional configuration. Instead of requiring axial extension of the translator to reach external bearings, the fluid bearing provides support through a different spatial relationship, eliminating the need for increased translator length
3Speed
If servo-hydraulic system is used to generate high frequency displacement, then road surface simulation is achieved, but system inertia limits practical frequency to approximately 150Hz
Solution Approach 1:
The patent replaces the servo-hydraulic system with a linear electromagnetic actuator system. This substitution eliminates the heavy hydraulic oil and associated infrastructure, dramatically reducing system inertia and enabling operation at frequencies远高于150Hz while maintaining the capability to generate high frequency displacements for road surface simulation
4Speed
If preload chamber is provided to balance translator weight, then friction is reduced, but device complexity increases
Solution Approach 1:
The patent merges the preload chamber function with the working chamber. The same chamber serves dual purposes: containing the working fluid that drives the translator and providing the preload necessary to balance translator weight and reduce friction. This integration eliminates the need for separate preload and working chambers, reducing device complexity
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 achieves higher frequency operation with lower inertia, reduced mechanical friction, and compact size, improving test subject input function integrity and reducing operational costs and noise.
Implementation Method 1
at least one fluid bearing between the central core and the translator provides coaxial location of the translator within the stator bore cavity
Implementation Method 2
a linear electrical machine (LEM) comprising a stator mounted in a housing, the housing and stator defining a working cylinder
Implementation Method 3
incorporating a preload chamber to balance the test subject weight
Implementation Method 4
using a labyrinth seal to maintain coaxial alignment
Data Source
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AI summary
A linear electrical machine (LEM) comprising a stator mounted in a housing, the housing and stator defining a working cylinder, a central core within the working cylinder and defining a cylindrical stator bore cavity therebetween, a hollow translator axially movable within the working cylinder, extending into the stator bore cavity and forming an exterior magnetic circuit airgap between the translator and the stator, at least one fluid bearing between the central core and the translator providing a bearing gap, wherein the central core is axially fixed in relation to the stator, wherein the at least one fluid bearing provides coaxial location of the translator and central core.