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Delphi will supply its "MagneRide" system in the first production application of magneto-rheological [MR] shock absorbers. The 2002 Cadillac Seville will be fitted with four suspension displacement sensors, a lateral accelerometer, a steering wheel angle sensor, and the MR dampers that make up the MagneRide system. What makes this technology unique is its reliance on iron particles suspended in synthetic fluid to control vehicle ride motions.

Non-MR shock absorbers use engineered orifices to adjust the speed of the fluid inside the unit, and thus control ride motions along a predefined curve. Electronically controlled versions expand the performance envelope by rotating a rod containing multiple orifices to change the damping Force. Unfortunately, each damping curve is fixed, and the electronic switching slow enough to limit effectiveness.

Less costly "passive" adjustable units, on the other hand, rely upon grooves Formed in the shock's inner walls to alter the damping curve. Oil flows Freely along these channels at slow wheel speeds [For a smooth ride], while Fast wheel movements use oil pressure to block the passages and increase the damping Force. There is no harsh switchover between the damping curves, but damping options are limited.

Magneto-rheological dampers use an electromagnetic coil inside the damper's piston to increase the fluid's viscosity by aligning the magnetic particles when a current is applied.

This on-off process can be controlled with great accuracy, allowing the creation of a near-infinite number of damping curves within the limits of the system. Developing a synthetic fluid capable of keeping the iron particles from clumping together was a distinct challenge, especially when the vehicle sits for extended periods. Delphi engineers say the work was worth the effort given the technology's advantages. It can be used to adjust the vehicle's dive, squat, and roll rates by adjusting the shock absorbers' damping rates individually, or in pairs.

Delphi says the shock absorbers are adjusted every millisecond based on readings From displacement sensors at each wheel, though it is not the "active" system the company claims it to be. A fully active suspension moves each wheel up and down independently, usually by way of high-pressure hydraulic rams. MagneRide adjusts the damping force at each corner of the vehicle in reaction to inputs from the road. Look For it to be bundled with Delphi's Traxxar stability system in future applications.
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Title Annotation:Delphi shock absorbers
Comment:MAGNETIC PERSONALITY FOR THE CTS?(Delphi shock absorbers)
Author:Sawyer, Christopher A.
Publication:Automotive Design & Production
Article Type:Brief Article
Geographic Code:1USA
Date:Oct 1, 2001
Next Article:Powering Up Fuel Cells.

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