A.Technology Invented.

PSA Peugeot Citroën.

According to Wikipedia 11 april 2012 state that PSA Peugeot Citroën (officially Peugeot S.A., informally PSA) is a French multinational manufacturer of automobiles and motorcycles sold under the Peugeot and Citroën marques. Headquartered in the 16th arrondissement of Paris, PSA is the second-largest Europe-based automaker (after Volkswagen Group) and the eighth-largest in the world measured by 2011 unit sales. PSA is listed on the Euronext Paris stock exchange and is a constituent of the CAC 40 index.

Hydractive.

Hydractive Suspension is a new automotive technology introduced by the French manufacturer(PSA PEUGEOT CITROEN) in 1990. It describes a development of the 1954 hydropneumatic  suspension design using additional electronic sensors and driver control of suspension performance. The driver can make the suspension stiffen (sport mode) or ride in outstanding comfort (soft mode). Sensors in the steering, brakes, suspension, throttle pedal and gearbox feed information on the car's speed, acceleration, and road conditions to on-board computers. Where appropriate, and within milliseconds, these computers switch an extra pair of suspension spheres in or out of the circuit, to allow the car a smooth supple ride in normal circumstances, or greater roll resistance for better handling in corners. This development keeps PSA in the forefront of suspension design, given the widespread goal in the auto industry of an active suspension system. All auto suspension is a compromise between comfort and handling. Auto manufacturers try to balance these aims and locate new technologies that offer more of both (Wikipedia May 2009).

Hydractive 1 and Hydractive 2.

Hydractive 1 suspension systems had two user presets, Sport and Auto. In the Sport setting the car's suspension was always kept in its firmest mode. In the Auto setting, the suspension was switched from soft to firm mode temporarily when a speed-dependent threshold in accelerator pedal movement, brake pressure, steering wheel angle, or body movement was detected by one of several sensors( Wikipedia May 2009).

In Hydractive 2, the preset names were changed to Sport and Comfort. In this new version the Sport setting would no longer keep the suspension system in firm mode, but instead lowered the thresholds significantly for any of the sensor readings also used in Comfort mode, allowing for a similar level of body firmness during cornering and acceleration, without the sacrifice in ride quality the Sport mode in Hydractive 1 systems had caused (Wikipedia May 2009).

Whenever the Hydractive 1 or 2 computers received abnormal sensor information, often caused by malfunctioning electrical contacts, the car's suspension system would be forced into its firm setting for the remainder of the ride (Wikipedia May 2009).

Hydractive 3.

As stated by Wikipedia  May 2009,hydractive 3 uses a new, incompatible orange LDS fluid, rather than the familiar green LHM mineral oil used in millions of hydropneumatics vehicles.

The hydractive 3 hydraulic suspension has 2 automatic modes:

§  Motorway position (lowering by 15 mm of the vehicle height above 110 km/h)

§  Poor road surface position (raising by 13 mm of the vehicle height below 70 km/h)

The BHI of the hydractive 3 suspension calculates the optimum vehicle height, using the following information:

§  Vehicle speed

§  Front and rear vehicle heights

The 3+ hydractive hydraulic suspension has 3 automatic modes:

§  Motorway position (lowering by 15 mm of the vehicle height above 110 km/h)

§  Poor road surface position (raising by 13 mm of the vehicle height below 70 km/h.

Comfort or dynamic suspension (variation of suspension firmness)

The BHI of the 3+ hydractive suspension calculates the optimum vehicle height, using the following information (Wikipedia may 2009) :

§  Vehicle speed

§  Front and rear vehicle heights

§  Rotation speed of steering wheel

§  Angle of rake of steering wheel

§  Vehicle's longitudinal acceleration

§  Vehicle's lateral acceleration

§  Speed of suspension travel

§  Movement of the accelerator throttle

    (Picture show by Lakshmi Anand k,2008)

History of the technology.

In World War II, Paul Magès, with no formal training in engineering, secretly develops the concept of an oil and air suspension to combine a new level of softness with vehicle control and self-levelling.

1989 -Citroën XM: Hydractive Suspension, electronic regulation of the hydropneumatic system; sensors measure acceleration and other factors.

1990 -Peugeot 405 Mi16x4: first Peugeot equipped with rear hydropneumatic suspension.

1990 -JCB Fastrac high speed agricultural tractor uses this system for its rear suspension.

1993 -Citroën Xantia: Optional Activa (active suspension) system, eliminating body roll by acting on torsion bars. A Xantia Activa was able to reach more than 1g lateral acceleration.

2001 -Citroën C5: Hydractive 3 removes the need for central hydraulic pressure generation; combined pump/sphere unit for the suspension only and with electric height adjustment sensors.

2005 -Citroën C6: An improved version of the C5 system known as Hydractive 3+ (also fitted to some C5 models).

2008- JCB Fastrac high speed 7000 series agricultural tractors now use this system for front and rear     suspension (Wikipedia May 2009) .