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36-417: These technologies allow car manufacturers to achieve a greater degree of ride quality and car handling by keeping the chassis parallel to the road when turning corners, preventing unwanted contacts between the vehicle frame and the ground (especially when going over a depression ), and allowing overall better traction and steering control. An onboard computer detects body movement from sensors throughout

72-555: A hydraulic oil pump, a hydraulic cylinder, an accumulator and damping valve, which connected two independent circuits for the front and rear strut assemblies. The system would then recover motion energy to balance the car continuously. The system was revised and is now called Hydraulic Body Motion Control System , installed on the Nissan Patrol and Infiniti QX80 . Williams Grand Prix Engineering prepared an active suspension, devised by designer-aerodynamicist Frank Dernie , for

108-481: A lower center of gravity is more ideal for handling, but low ground clearance limits suspension travel and requires stiffer springs. Ambulances have a special need for a high level of ride quality to avoid further injury to the already-ill passengers. Early vehicles, like the Ford Model T , with its leaf spring , live axle suspension design, were both uncomfortable and handled poorly. Historically, weight

144-413: A microcomputer would then interpret, combined with information from the steering, brakes, throttle, and vehicle speed sensor. The adjustment information signals would then modify the shock absorbers when a driver-controlled switch was placed in "Auto". The automatic adjustment could be limited if the switch was placed in "Soft," "Medium," or "Hard" settings. A modified version that didn't use the sonar module

180-499: A more comfortable ride. Unlike other similar systems, this does not need a power source, so there is no trade-off with fuel economy. Fluid from the two outside wheel hydraulic cylinders flows to the accumulator to raise the suspension's roll stiffness. This counteracts centrifugal force, reducing the degree of sinking on the vehicle's outer side and helps to minimize passenger fluctuation of view. The suspension for each wheel rises or drops according to road conditions, smoothly absorbing

216-628: A platform with the Infiniti QX. The system was also introduced in similar form on the 2011 Infiniti QX. An earlier version of the system was installed in the Nissan President and Infiniti Q45 called Full Active Suspension from 1990-2002. Two hydraulic systems connected by cross-link hydraulic pipes to the 4-wheel independent suspension's hydraulic cylinders absorb road bumps and help reduce body lean when cornering. This helps minimize fluctuation of view of those on board and provides

252-550: Is by using computer-controlled suspensions, such as hydraulic active suspension system (like Active Body Control ) or active anti-roll bars, but such systems are expensive because of their complexity. The main factor affecting ride quality is the stiffness of suspension components (e.g. springs , shock absorbers , anti-roll bars and bushings ). Other factors include suspension geometry, vehicle mass and weight distribution . Hydraulic Body Motion Control System The Hydraulic Body Motion Control System (HBMC) technology

288-463: Is calculated based on the value provided by an acceleration sensor installed on the body of the vehicle (see Figure 3). The dynamic elements comprise only the linear spring and the linear damper; therefore, no complicated calculations are necessary. A vehicle contacts the ground through the spring and damper in a normal spring damper suspension, as in Figure 1. To achieve the same level of stability as

324-487: Is used to calculate the optimal stiffness at that point in time. The fast reaction of the system (milliseconds) allows, for instance, making a softer passing by a single wheel over a bump in the road at a particular instant in time. By calendar year: Ride quality Ride quality refers to a vehicle's effectiveness in insulating the occupants from undulations in the road surface such as bumps or corrugations. A vehicle with good ride quality provides comfort for

360-567: The Vehicle Dynamics Control technology to modify the transmission's shift points. The settings are labeled as Normal, Comfort, or R, and can be either set in Normal for automatic adjustment or the "R" setting for high-speed driving, while "Comfort" is for touring and a more compliant ride. The "R" mode enables the vehicle to utilize the yaw angle rate with a reduced steering angle for a crisper, more communicative steering, while

396-420: The hydropneumatic suspension developed by Paul Magès at Citroën . The hydraulic pressure is supplied by a high pressure radial piston hydraulic pump . Sensors continually monitor body movement and vehicle ride level, constantly supplying the hydraulic height correctors with new data. In a matter of a few milliseconds, the suspension generates counter forces to raise or lower the body. During driving maneuvers,

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432-493: The shock absorber , and do not add energy to the suspension system. While adaptive suspensions have generally a slow time response and a limited number of damping coefficient values, semi-active suspensions have time response close to a few milliseconds and can provide a wide range of damping values. Therefore, adaptive suspensions usually only propose different riding modes (comfort, normal, sport...) corresponding to different damping coefficients, while semi-active suspensions modify

468-496: The suspension settings via electronically controlled dampers . The 1999 Mercedes-Benz CL-Class (C215) introduced Active Body Control , where high pressure hydraulic servos are controlled by electronic computing, and this feature is still available. Vehicles can be designed to actively lean into curves to improve occupant comfort. Active anti-roll bar stiffens under command of the driver or suspension electronic control unit (ECU) during hard cornering. First production car

504-405: The "Comfort" setting produces less vertical G-loading in comparison to the "Normal" or computer determined suspension setting. Another method incorporates magnetorheological dampers with a brand name MagneRide . It was initially developed by Delphi Corporation for GM and was standard, as many other new technologies, for Cadillac STS (from model 2002), and on some other GM models from 2003. This

540-501: The Skyhook theory, the vehicle must contact the ground through the spring, and the imaginary line with the damper, as in Figure 2. Theoretically, in a case where the damping coefficient reaches an infinite value, the vehicle will be in a state where it is completely fixed to the imaginary line, thus the vehicle will not shake. Active suspensions, the first to be introduced, use separate actuators which can exert an independent force on

576-495: The computer with new data. As the computer receives and processes data, it operates the hydraulic servos, mounted beside each wheel. Almost instantly, the servo-regulated suspension generates counter forces to body lean, dive, and squat during driving maneuvers. In 1990, Nissan installed a hydraulic supported MacPherson strut based setup, called Full-Active Suspension that was used in the Nissan Q45 and President. The system used

612-567: The control algorithm (usually the so-called "Sky-Hook" technique). This type of system is used in Cadillac's Computer Command Ride (CCR) suspension system. The first production car was the Toyota Soarer with semi-active Toyota Electronic Modulated Suspension , from 1983. In 1985, Nissan introduced a shock absorber using a similar version, called "Super Sonic Suspension," adding an ultrasonic sensor that would provide information that

648-453: The damping in real time, depending on the road conditions and the dynamics of the car. Though limited in their intervention (for example, the control force can never have different direction than the current vector of velocity of the suspension), semi-active suspensions are less expensive to design and consume far less energy. In recent times, research in semi-active suspensions has continued to advance with respect to their capabilities, narrowing

684-495: The driver and the passengers. Good ride quality provides comfort for the people inside the car, minimises damage to cargo and can reduce driver fatigue on long journeys in uncomfortable vehicles, and also because road disruption can impact the driver's ability to control the vehicle. Suspension design is often a compromise between ride quality and car handling because cars with firm suspension can result in greater control of body movements and quicker reactions. Similarly,

720-709: The encased nitrogen compresses instantly, offering six times the compressibility of the steel springs used by vehicles up to this time. In practice, the system has always incorporated the desirable self-levelling suspension and height adjustable suspension features, with the latter now tied to vehicle speed for improved aerodynamic performance, as the vehicle lowers itself at high speed. This system performed remarkably well in straight ahead driving, including over uneven surfaces, but had little control over roll stiffness. Millions of production vehicles have been built with variations on this system. Colin Chapman developed

756-412: The gap between semi-active and fully active suspension systems. This type is the most economic and basic type of semi-active suspensions. They consist of a solenoid valve which alters the flow of the hydraulic medium inside the shock absorber , therefore changing the damping characteristics of the suspension setup. The solenoids are wired to the controlling computer, which sends them commands depending on

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792-425: The left and right sides of the vehicle through passive weight transfer during normal driving. It also helps reduce bump shock by setting bounce and roll damping forces separately. In off-road conditions, HBMC activates when it senses that a wheel has dropped. The hydraulic Body Motion Control System was first available on the new model year 2010 Nissan Patrol, a sport utility vehicle that is sold worldwide, and shares

828-419: The onboard computer, the dampers' compliance characteristics are controlled by an electromagnet . Essentially, increasing the current flow into the damper magnetic circuit increases the circuit magnetic flux. This in turn causes the metal particles to change their alignment, which increases fluid viscosity thereby raising the compression/rebound rates, while a decrease softens the effect of the dampers by aligning

864-426: The original concept of computer management of hydraulic suspension in the 1980s to improve cornering in racing cars. Lotus fitted and developed a prototype system to a 1985 Excel with electro-hydraulic active suspension, but never offered it for sale to the public, although many demonstration cars were built for other manufacturers. Sensors continually monitor body movement and vehicle ride level, constantly supplying

900-493: The particles in the opposite direction. If we imagine the metal particles as dinner plates then whilst aligned so they are on edge - viscosity is minimised. At the other end of the spectrum they will be aligned at 90 degrees so flat. Thus making the fluid much more viscous. It is the electric field produced by the electromagnet that changes the alignment of the metal particles. Information from wheel sensors (about suspension extension), steering, acceleration sensors - and other data,

936-420: The suspension to improve the riding characteristics. The drawbacks of this design are high cost, added complication and mass of the apparatus, and the need for frequent maintenance on some implementations. Maintenance can require specialised tools, and some problems can be difficult to diagnose. Hydraulically actuated suspensions are controlled with the use of hydraulics . The first example appeared in 1954, with

972-494: The team's Formula 1 cars in 1992, creating such successful cars that the Fédération Internationale de l'Automobile decided to ban the technology to decrease the gap between Williams F1 team and its competitors. Computer Active Technology Suspension (CATS) co-ordinates the best possible balance between ride quality and handling by analysing road conditions and making up to 3,000 adjustments every second to

1008-424: The vehicle and, using that data, controls the action of the active and semi-active suspensions. The system virtually eliminates body roll and pitch variation in many driving situations including cornering , accelerating and braking . When used on commercial vehicles such as buses , active suspension can also be used to temporarily lower the vehicle's floor, thus making it easier for passengers to board and exit

1044-466: The vehicle. Skyhook theory is that the ideal suspension would let the vehicle maintain a stable posture, unaffected by weight transfer or road surface irregularities, as if suspended from an imaginary hook in the sky continuing at a constant altitude above sea level, therefore remaining stable. Since an actual skyhook is obviously impractical, real active suspension systems are based on actuator operations. The imaginary line (of zero vertical acceleration)

1080-399: Was Mitsubishi Mirage Cyborg in 1988. In fully active electronically controlled production cars, the application of electric servos and motors married to electronic computing allows for flat cornering and instant reactions to road conditions. The Bose Corporation has a proof of concept model. The founder of Bose, Amar Bose , had been working on exotic suspensions for many years while he

1116-497: Was also used, allowing the settings to be manually selected. This implementation is currently used industry-wide by a number of manufacturers, provided by Monroe Shock Absorbers called CVSAe, or Continuously Variable Semi-Active electronic. In 2008, with the introduction of the Nissan GT-R , "DampTronic" was jointly developed by Nissan and Bilstein. DampTronic provides three selectable driver settings that can also interact with

Active suspension - Misplaced Pages Continue

1152-406: Was an MIT professor. Electromagnetic active suspension uses linear electromagnetic motors attached to each wheel. It provides extremely fast response, and allows regeneration of power consumed, by using the motors as generators. This nearly surmounts the issues of slow response times and high power consumption of hydraulic systems. Electronically controlled active suspension system (ECASS) technology

1188-511: Was an upgrade for semi-active systems ("automatic road-sensing suspensions") used in upscale GM vehicles for decades. It allows, together with faster modern computers, changing the stiffness of all wheel suspensions independently. These dampers are finding increased usage in the US and already leases to some foreign brands, mostly in more expensive vehicles. This system was in development for 25 years. The damper fluid contains metallic particles. Through

1224-569: Was employed initially in the Nissan Patrol , and subsequently the Infiniti QX . The system was invented and developed by Nissan Motors and was tested on the Nissan Patrol in the Middle East. The system helps reduce body lean while turning for a more comfortable ride. Utilizing hydraulic cylinders located at the shock absorbers (connected via cross piping and two accumulators), it adjusts roll stiffness by allowing transfer of fluid between

1260-708: Was key to allowing cars such as the Rolls-Royce Silver Cloud and the Cadillac in the 1950s and the 1960s to have a more comfortable ride quality. However, there are various drawbacks to heavier cars, including poor fuel efficiency , acceleration, braking, cornering and additional stresses on components. Over time, technology has shifted the curve outward and so it is possible to offer vehicles that are extremely comfortable and still handle very well or vehicles with excellent handling that are also reasonably comfortable. One technical solution for offering both excellent comfort and reduced or eliminating body roll

1296-481: Was patented by the University of Texas Center for Electromechanics in the 1990s and has been developed by L-3 Electronic Systems for use on military vehicles. The ECASS-equipped Humvee exceeded the performance specifications for all performance evaluations in terms of absorbed power to the vehicle operator, stability and handling. Adaptive or semi-active systems can only change the viscous damping coefficient of

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