Hydro-magnetic Linear Actuator for Automotive Road Load Simulation
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Solution Overview
Problem
Existing servo-hydraulic systems used in automotive testing are limited by inertia, require bulky and expensive infrastructure, consume excessive power, generate noise, and introduce unwanted resonances, making them inefficient and costly for simulating high-frequency road loads and vibrations.
Innovation Solution
A linear electrical machine (LEM) actuator with a stator and axially movable translator, incorporating fluid bearings for low friction and reduced mass, a preload chamber for balancing loads, and a magnetic circuit airgap to maintain coaxial alignment and minimize inertial mass, allowing for higher frequency operation and reduced system size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If servo-hydraulic systems are used to simulate road loads, then the system can generate high forces, but the inertia of hydraulic oil and components limits the practical frequency to approximately 150 Hz
Solution Approach 1:
The patent replaces the servo-hydraulic mechanical system with a linear electromagnetic motor (LEM) system. The LEM directly converts electrical energy to mechanical motion without requiring hydraulic fluid, eliminating the inertia associated with hydraulic oil and servo-hydraulic power pack components. This substitution enables operation at frequencies significantly higher than the 150 Hz limit of hydraulic systems.
2Force
If servo-hydraulic systems are used, then high forces can be generated, but expensive and bulky infrastructure is required that must be located close to actuators
Solution Approach 1:
The patent extracts and eliminates the bulky servo-hydraulic power pack and associated infrastructure from the system. By using electrically driven linear electromagnetic motors, the system removes the need for hydraulic reservoirs, pumps, filters, and other supporting infrastructure that must be located close to actuators. The force generation capability is maintained through the LEM while the infrastructure complexity is dramatically reduced.
3Force
If servo-hydraulic systems are used, then force control is achieved, but power consumption is excessive
Solution Approach 1:
The patent substitutes the energy-intensive hydraulic power generation system with electrically driven linear electromagnetic motors. The LEM converts electrical energy directly to mechanical force with high efficiency, eliminating the continuous power consumption required by hydraulic pumps and motors. This substitution maintains precise force control capability while dramatically reducing overall power consumption and carbon emissions footprint.
4Speed
If servo-hydraulic systems are used, then road load simulation is achieved, but extreme noise is generated that masks test subject response
Solution Approach 1:
The patent replaces the noisy hydraulic system with electrically driven linear electromagnetic motors. The LEM operates with minimal mechanical friction and no hydraulic fluid movement, eliminating the extreme noise generated by hydraulic pumps, valves, and fluid flow. This substitution enables accurate measurement of test subject response by removing the noise mask that previously made it difficult to differentiate test subject response from system noise.
5Force
If traditional actuators with springs and pneumatic cylinders are used, then static load balancing is achieved, but additional inertial mass reduces peak frequencies
Solution Approach 1:
The patent replaces mechanical spring and pneumatic cylinder systems with an electrically controlled linear electromagnetic motor system. The LEM uses electromagnetic fields to provide both static load balancing and dynamic force control without requiring physical springs or pneumatic components. This substitution eliminates the additional inertial mass that would otherwise reduce peak frequency operation, enabling the system to achieve higher frequencies while maintaining load balancing capability.
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 actuator achieves higher frequency operation with lower inertia and mechanical friction, reducing system size and cost while minimizing resonances and noise, enabling more accurate simulation of road loads and vibrations.
Implementation Method 1
a linear electrical machine (LEM) having a stator with a stator bore and a translator that is axially movable within the stator bore
Implementation Method 2
at least one fluid bearing providing a bearing gap adjacent the translator to allow the translator to move axially within the stator bore
Data Source
AI summary
An actuator comprising a linear electrical machine (LEM) having a stator with a stator bore and a translator axially movable within the stator bore and defining a magnetic circuit airgap therebetween, at least one fluid bearing journal formed on the translator, at least one fluid bearing providing a bearing gap adjacent the translator to allow the translator to move axially within the stator bore, a preload chamber for applying a preload force to the translator, wherein the preload chamber is defined by a side wall, a first end wall and a second end wall at least part of which is movable with the translator, and wherein the bearing gap and the magnetic circuit airgap are coaxial.