MagneRide
MagneRide is an automotive adaptive suspension with magnetorheological damper system developed by the Delphi Automotive corporation, during a period when the company was a subsidiary of General Motors (GM), that uses magnetically controlled dampers, or shock absorbers, for a highly adaptive ride. As opposed to traditional suspension systems, MagneRide has no mechanical valves or even small moving parts that can wear out. 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. 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 effective 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. 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. History. The first generation was created by Delphi Corporation during a period when it was a subsidiary of General Motors (GM), and debuted on the 2002.5 Cadillac Seville STS. The first sports car to use the technology was the 2003 C5 Corvette. The piston inside  these dampers contained a single electromagnetic coil. Improvements. Generation II MagneRide continued to use a single electromagnetic coil inside the damper piston. Changes from the previous generation include uprated seals and bearings to extend its application to heavier cars and SUV's. The most notable improvements in the new system are the ECU and coils. A smaller, lighter, more capable ECU debuted with GenII 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. It also has greater tuneability. Dual coils. The third generation introduced a second electromagnetic coil in the piston of each damper, improving turn-off response. 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. BWI greatly reduced this delay with its dual coil system. The two coils are wound in opposite  directions to each other, cancelling out the eddy currents. 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 (2002.5) sedan, first used in a sports car in the 2003 C5 Corvette, 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 Holden Special Vehicles, Ferrari, Ford and Audi vehicles. Specific Applications: