Tech Briefs
February 2002
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Volvo goes all out
 The new Volvo S60 AWD is the first Volvo with electronically controlled all-wheel drive (AWD). The Active-On-Demand system was developed in collaboration with the Swedish company Haldex Group. |
The Volvo S60 AWD, the first Volvo with electronically controlled all-wheel drive (AWD), was introduced at the Frankfurt Motor Show in September. The Active-On-Demand (AOD) AWD system was developed in collaboration with the Swedish company Haldex Group and provides "nearly instantaneous" power distribution between the front and rear wheels, says Volvo Car Corp.
As with Volvo's previous AWD systems, the new AOD system operates automatically, independent of the driver. According to the automaker, its advantages are the "speed and sophistication" with which it operates. "The speed of the system gives (the) car exceptionally good road handling," said Hans Gustavsson, Senior Vice President of Research, Development, & Purchasing at Volvo Car Corp. "After all, the owner of a sedan does not use all-wheel-drive for off-road accessibility but for optimal road-holding and stability."
 The system's differential electronic module communicates with the engine control module and brake control module via the control area network (CAN) to determine loss of traction and to anticipate different driving situations. Click to enlarge |
In normal driving conditions, the S60 AWD has a front-wheel-drive bias for fuel-efficiency benefits. The AWD system selectively delivers power to the rear wheels when it detects that the front wheels have lost traction and have begun to spin. When a speed difference occurs between the front and rear wheels, power is distributed to the rear wheels via a mechanical pump and a wet multiplate clutch. The pump forces oil to a clutch piston, which compresses the wet clutch plates in the rear differential to transfer power, consequently reducing the speed difference. The oil pressure on the plates determines the torque that can be transferred to the rear wheels. A small electrical pump is used to "pre-pressurize" the system to ensure expeditious power transfer; pressure is reduced when both axles are rotating at the same speed, bringing the drive wheels into equilibrium.
The system is electronically controlled through a module mounted on the rear differential, which forms a unit with the stepper motor and the control valve. The differential electronic module (DEM) communicates with the engine control module and brake control module via the control area network to determine loss of traction and to anticipate different driving situations. The DEM uses sensor signals to control oil pressure on the wet clutch plates by adjusting the control valve. According to Volvo, the system can react to as little as a quarter turn difference between the input shaft and output shaft of the differential.
The electronically controlled AWD system is "intelligent"; by measuring front wheel spin, throttle position, and other data, the system can determine how quickly to distribute power and how much power to distribute. When accelerating on a difficult surface such as gravel, the rear wheels can be engaged quickly with maximum power transfer. Conversely, when cornering or parking at lower engine speeds, the system knows that the difference in speed between the wheels does not require engagement. As a result, the inertia experienced with other systems in similar situations is avoided, according to the company. In addition, it does not require special consideration in specific situations such as towing and tire changing, which can be carried out as normal.
 The S60 AWD's electronically controlled coupling/differential unit. Click to enlarge |
The AWD is connected to the vehicle's multiplex computer system. As a result, it is integrated with other systems in the car—including the ABS, the traction control system, and the optional Dynamic Stability Traction Control system—to optimize AWD during all driving situations.
Volvo says the AWD system did not affect the S60's trunk and fuel tank in terms of space.
- Ryan Gehm
Johnson Controls shows vision of luxury
 Interior view showing a conventional presentation—meaning a visible steering wheel—in the Ariston concept from Johnson Controls. |
An interior concept from Johnson Controls grabs attention by what is not seen: no instrument panel clutter, no immediate steering wheel sighting, no one-size fits all mentality. First shown at the Frankfurt Auto Show, the concept Ariston reveals the interior-system provider's vision of future generation luxury. "What we're trying to do is experiment with creating systems that leverage the senses to communicate information and to allow the consumer to control and interact with the environment more effectively," said Bill Fluharty, Vice President of New Product Strategy and Industrial Design for Johnson Controls.
The immediate sense of "something different" begins upon entering the vehicle. "There's no visual icon that says 'go-go-go'," said Fluharty, referencing the retractable steering wheel, which folds up and slides into the instrument panel horizontally whenever a driver exits the vehicle. The system returns the steering wheel to its functional position with a tug of an exposed steering wheel section.
Interior lighting via multi-colored LEDs within the headliner and door panels conveys both mood and performance perceptions. The HVAC system, which is linked to illumination settings, uses color—red for heat, blue for cool—to confirm that the heating and cooling system has registered the desired temperature. Personal color preferences can be dialed-in to establish mood lighting. "The headliner has metallic fibers woven into it, so the whole headliner surface actually looks like it's glowing," said Fluharty.
The gauge cluster zone on the instrument panel uses ultraviolet light. "It doesn't match how it would be in production, which would be an electro-luminescent display," said Fluharty, noting that the presentation (whether UV light or electroluminescent) conveys a flatter gauge package. Other lighting sources include the headliner's map/task lights. The driver or passenger need only rub their hand over a headliner bezel, "so you don't have to look up," said Fluharty.
Access to the vehicle's infotainment system follows a concept theme of less being more. At the base of the windshield is a vertical surface that functions as a display zone and links to a multi-controller in the armrest. "The idea is to have a clean surface to calm down the interior and create a sculpture with the (instrument panel)," said Fluharty, noting that the armrest controller bypasses the need for having "within reach" controls on the center stack.
Ariston's overall interior avoids visual technology overload. "Even though the technology is still there, it's integrated into the interior aesthetic," said Fluharty. The interior concept, representing technology likely eight to ten years from production, spanned a roughly six month interval involving four Johnson Controls industrial designers. "We've innovated the interior to compliment the innovations in exterior architecture," said Fluharty. "The interior has to fulfill the promise of the exterior that a car is really unique."
- Kami Buchholz
