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BMW 5 Series Gran Turismo
Classic GT substance in contemporary SAV flavour
(6/9 >>>>)

 Suspension

BMW 530d Gran Turismo: front static view.

Standard air suspension on the rear axle.

The 5 Series Gran Turismo gets a suspension combining a double track control arm front axle and an Integral-V rear axle. It comes as standard with air suspension on the rear axle (optimised over the system featured on the BMW 5 Series Touring) and 18-inch light-alloy wheels  (19-inch on the BMW 550i Gran Turismo).

The air suspension calculates the slightest change in the load the car is carrying, setting off different load conditions individually on each wheel and thus minimising the need for subsequent control action in response to spring movement caused by bumpy surfaces and body roll in bends. In the event of rear tyre damage, the air suspension takes the load off the wheel involved and sets off the difference in ride height caused by the loss of pressure.

Standard 245/45 R 19 runflat safety tyres are fitted at the front and 245/40 R 19 runflat tyres at the rear of the 550i Gran Turismo. The 535i and 530d get 245/50 R 18 runflat tyres front and rear. Runflat tyres enable the driver to continue after a puncture, even if the tyre is completely empty, covering up to 250 kilometres or 155 miles. A Tyre Defect Indicator permanently monitors tyre pressure, warning the driver as soon as pressure drops by more 20 per cent of the normal level.

 Dynamic Drive Control

The standard Dynamic Drive Control adapts the suspension set-up according to current requirements and preferences. The system varies the progressive curve of the gas pedal, engine response, the steering assistance, the shift dynamics of the eight-speed automatic transmission and the response thresholds of DSC Dynamic Stability Control.

530d Gran Turismo: driving shot, side view.

Standard Dynamic Drive Control: Normal, Sport or Sport+.

From a button on the centre console directly next to the gear selector lever. the driver can choose between Normal, Sport or Sport+ modes, in each case activating a pre-configured set-up based on corresponding settings of the drivetrain and suspension components.

The SPORT mode provides a more direct steering behaviour with a more spontaneous response to the gas pedal. It allows even individual configurations. In principle, this mode gives both the drivetrain and suspension functions a sporting set-up. Through the iDrive control system the driver can also influence one of these two factors, returning in this way to the usual configuration in the NORMAL mode. This allows the driver, for instance, to get a more sporting set-up of the drivetrain components without a harder set-up of the dampers if the road conditions are bad.

Another button directly in front of the mode toggle switch serves to choose the appropriate DSC settings. The driver can activate a special traction mode facilitating the process of setting off on snow. This is done through DTC Dynamic Traction Control (one of the DSC functions), which raises the response thresholds of the driving stability system.

BMW 530d Gran Turismo, driving shot, curve approach.

The DTC function is also activated in the Sport+ mode, allowing a slight slip on the drive wheels for a controlled powerslide.

The DTC function of the DSC system is also activated in the SPORT+ mode, serving in this case to allow a slight slip on the drive wheels for taking a bend in a controlled drift or powerslide.

The DSC can be deactivated by keeping the finger on the DCS settings button somewhat longer. In this DSC-Off mode, an electronic locking function acts on the rear axle differential, enhancing dynamic driving, for example when accelerating out of a bend. To optimise traction under such conditions, a drive wheel spinning when accelerating out of a tight bend is slowed down precisely by the brakes, allowing the opposite wheel on the same axle to maintain the drive power and traction required.

  Adaptive Drive

An optional Adaptive Drive system combines electronically controlled dampers and active anti-roll stability system. Each damper has individual adjustment for inbound and rebound strokes in a continuous, independent process, adapting to road conditions and the driving style.

BMW 5 Series GT: frameless windows, front view.

BMW 5 Series GT: frameless windows, rear view.

BMW 5 Series GT: sleek, fastback-like rear end.

Frameless windows and sleek, fastback-like rear end.

The driver can adjust the damper control map through the Dynamic Drive Control, choosing between comfortable, normal or sporting settings.

The damping system has infinite and independent adjustment of the inbound and rebound strokes, with a combination of a firm suspension set-up and, at the same time, a comfortable response to bumps and unsmooth surfaces on the road.

With these dampers, the up-and-down movement of each wheel is determined by sensors and reported to the central control unit, taking these data and signals on the car's ride height to determine any movement of the body. Making allowance also for road speed and the damper setting chosen by the driver, the system then calculates the damper force required on each wheel in order to reduce body movements.

The data used for this purpose is fed to the dampers in intervals of 2.5 milliseconds, with actual and target settings being established individually on each wheel by controlling the inbound and rebound stroke valves in the dampers.

The Adaptive Drive system comes with active anti-roll stabilisation. Sensors determine the side angle of the body while swivel motors in the anti-roll bars front and rear counteract the forces recorded, improving the car's steering and load change behaviour. Side roll is also reduced with bumps on just one side of the road.

  Integral Active Steering

The standard hydraulic rack-and-pinion steering comes with a Servotronic on-demand steering assistance pump. In a straight line, the volume flow from the pump is reduced electrically, cutting back the power uptake accordingly. This reduction of energy consumption is part of the car's EfficientDynamics technologies.

As an option, the 5 Series Gran Turismo may be equipped with the Integral Active Steering. Depending on road speed, this system influences steering forces through the Servotronic function, as well as the steering angle via the additional transmission unit acting through Active Steering on the front axle.

Integral Active Steering also controls the steering angle on the rear wheels through a concentrically arranged motor with spindle drive acting on the rear axle. It varies the steering angle both front and rear through an electric motor controlled by an electronic unit receiving data on wheel speed, movements of the steering wheel, yaw rate and lateral acceleration.

The maximum steering angle on the rear wheels is 2.50. At low speeds the rear wheels turn against the steering angle on the front wheels to enhance agility, reducing the turning circle. The subsequent reduction of steering forces increases comfort.

At higher speeds, Integral Active Steering provides better response when changing lanes and in bends, with the rear wheels turning in the same direction as the front wheels.

In abrupt steering manoeuvres the 5 Series Gran Turismo again follows the driver's steering movements with precision.

Intervening at the same time on both axles, active steering also optimises steering response and reduces the movements of the steering wheel required. A further effect of rear-wheel steering is particularly significant at the rear: any change in direction under dynamic driving conditions builds up lateral acceleration without a corresponding increase in the yaw rate. The separation of these two factors gives the passengers particularly at the rear extra comfort and a smoother ride.

BMW says that the combination of Active Steering on the front axle and rear axle steering offers extra stability in fast directional manoeuvres, making braking manoeuvres smoother.

Combining Active Steering with the DSC Dynamic Stability Control sensors, the system can help prevent the car from swerving out of control when braking on different surfaces left and right, by intervening specifically in the steering as required.

  ICM

The operation and interaction of the suspension systems is handled by the Integrated Chassis Management (ICM) network, which connects the various functions with one another. This high-performance electronic management analysing the car's behaviour by evaluating a large number of sensor signals, serves to coordinate drivetrain and suspension functions within fractions of a second for maximum stability under all conditions.

Even under suddenly changing conditions for example on changing road surfaces, with spontaneous steering manoeuvres, abrupt acceleration or application of the brakes ICM intervenes immediately by adjusting the DSC actuators and, where fitted, acting on the Integral Active Steering and Adaptive Drive.

To get achieve this coordination between all systems, BMW uses FlexRay high-speed data transmission, for its data transfer capacity at a rate 20 times higher than that of a conventional transmission system.

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