MagneRide

MagneRide is an automotive suspension system owned by Beijing World Industries Group that utilizes magnetically controlled dampers, or shock absorbers, for a highly adaptive ride. As opposed to traditional suspension systems, MagneRide has no mechanical valves or small moving parts that can wear out. ^[1]This system consists of four monotube dampers, one on each corner of the vehicle, a sensor set, and an ECU (Electronic Control Unit) to maintain the system.

Background

The dampers are filled with magnetorheological fluid, a mixture of easily magnetized iron particles in a synthetic hydrocarbon oil. In each of the monotube dampers is a piston containing two electromagnetic coils and two small fluid passages through the piston. The electromagnets are able to create a variable magnetic field across the fluid passages. When the magnets are off, the fluid travels through the passages freely. However, when the magnets are turned on, the iron particles in the fluid create a fibrous structure through the passages in the same direction of the magnetic field. The strength of the bonds between the magnetized iron particles causes the viscosity of the fluid to increase resulting in a stiffer suspension. Altering the strength of the current results in an instantaneous change in force of the piston.^[2] If the sensors sense any body roll, they communicate the information to the ECU. The ECU will compensate for this by changing the strength of the current to the appropriate dampers.

Differentiating Features

• Low-velocity damping control
• Ability to ‘draw’ Force-Velocity curve
• Fast response

Ride and Handling Performance: Easier to drive on challenging surfaces; “Blend of balance and grip is near perfect”.^[3]

History

The current application of MagneRide is the third generation. The first generation was created by Delphi Corporation and debuted on the Cadillac Seville STS. Previous generations of MagneRide were made of more primitive dampers. The piston inside these dampers contained a single, large electromagnetic coil. The ECU was made of lead and had reached the limit of its potential.

Improvements

The previous generations were used as a basis for BWI's newest version of Magneride. Changes from the previous generation include uprated seals and bearings to extend its application to heavier cars and SUV's.^[4] The most notable improvements in the new system are the ECU and coils.

Improved ECU

The legislative requirement for lead-free ECU's caused BWI to redesign their control unit for the third generation. Because they could not use lead, BWI designed their new ECU from scratch. The new and improved ECU has three times the computing capacity as the previous edition as well as ten times more memory.^[5] It also has greater tuneability.

Dual Coils

As opposed to the previous generation's single coil, the third generation brought two smaller coils in each damper. With the single electromagnetic coil, there was a small delay from when the ECU turned off the current to when the damper lost its magnetic field. This was caused by a temporary electric current, or eddy current, in the electromagnet. This phenomenon resulted in a 20ms delay in reaction time of the dampers. BWI eliminated this delay with its dual coil system. The two coils are wound in opposite directions to each other, cancelling out the eddy currents.^[6] The dual coil system effectively eliminated the delay, causing a quicker responding suspension system.

Applications

MagneRide was first used by General Motors in the Cadillac Seville STS (2002) and is now used as a standard suspension or an option in many models for Cadillac, Buick, Chevrolet, and other GM vehicles. It can also be found on some non-US vehicles such as: Holden Special Vehicles, Ferrari, and Audi.

Specific Applications:

• Chevrolet Corvette C5
• Chevrolet Corvette C6: optional in coupe trim starting in 2005 model year and in hardtop (Z06) trim starting in 2012 model year; standard equipment in ZR1
• Chevrolet Camaro in ZL1 trim (2012-)
• Cadillac CTS-V (2009-)^[7]
• Ferrari 599
• Ferrari California
• Audi TT
• Audi R8 ^[8]
• Acura MDX^[9]
• Acura ZDX^[10]
• Range Rover Evoque^[11]

Disadvantages

• Due to its high price, MagneRide is only available on higher end vehicles and sports cars.
• MR fluid can thicken after continual use and need replacing.

References

1. ^ Economist, Vol. 371 Issue 8379
2. ^ http://www.bwigroup.com/static/suspension_magneride/
3. ^ "MagneRide Performance and Challenges". Vehicle Dynamics Exop PDF. http://www.vehicledynamics-expo.com/08vdx_conf/pdf/day_1/olivierraynauld.pdf. 
4. ^ Professional Engineering, "Smooth Ride"
5. ^ Automotive Engineer, "Core Technology"
6. ^ http://www.automotive-electronicspecifier.com/Chassis-and-Steering/Third-Generation-Of-Bwi-Magneride-Ride-Control-Technology-Debuts-In-New-Range-Rover-Evoque.asp
7. ^ http://jalopnik.com/5834845/cadillac-disses-ferrari-in-new-ad?utm_medium=referral&utm_source=pulsenews
8. ^ http://www.dailymotion.com/video/x7epd9_audi-r8-magnetic-ride_auto
9. ^ http://www.acura.com/VideoGallery.aspx?model=MDX&modelYear=2011&context=photos-videos#/video1
10. ^ http://www.acura.com/VideoGallery.aspx?model=MDX&modelYear=2011&context=photos-videos#/video1
11. ^ http://www.topgear.com/uk/car-news/land-rover-evoque-driven-2011-03

External links

• [1]
• [2]