start/stop technology in cars with automatic gearbox

[Ben]

Volvo Car Corporation now makes it possible for customers to combine fuel-cutting start/stop technology with an automatic gearbox.
The new start/stop technology, which initially is available together with the 2.0-litre D3 turbo diesel, cuts CO2 emission with 10 g/km - translated into 0.4 litres less fuel consumption per 100 km.


From early September 2011, the six-speed automatic gearbox with start/stop becomes available in the D3 versions of four Volvo models: S60, V60, V70 and S80.


"Continuously reducing CO2 emissions from conventional powertrains is an important part of our DRIVe Towards Zero emissions. It is the most effective way to cut CO2 throughout our model range in the short term. This work is running parallel with our innovative focus on electrification technologies," says Peter Mertens, Senior Vice President Research and Development at Volvo Car Corporation.


Combining start/stop with automatic gearbox is a larger technology challenge than the manual start/stop version already available in most Volvo models. The engine must restart instantly when the driver moves the right foot from the brake pedal to the accelerator.


Agile response
"We have focused on achieving the same agile feeling as you get with today's conventional automatic. The response is so seamless that it feels like the car starts accelerating immediately when the engine restarts," explains Peter Mertens.


The technology uses brake pressure measurement to trigger when to stop and start the engine. The start/stop system is programmed to shut down the engine immediately when the car reaches a standstill (0 km/h).
An electric pump keeps oil pressure up in the automatic gearbox while the engine is stopped. The system also includes an improved starter engine.


Downsized five-cylinder engine
The two-litre D3 produces 163 hp and 400 Nm of torque. The five-cylinder 2-litre turbo diesel was introduced 2010 in the all-new Volvo S60. It is now available throughout Volvo Car Corporation's model range.
The five-cylinder D3 is in principle the same engine as the well-established 2.4-litre diesel, but its displacement has been reduced with a shorter stroke to optimise fuel consumption.


The piezoelectric fuel injectors minimise consumption with exceptionally rapid and precise injection pulses under high pressure. This promotes extremely efficient combustion. In order to give the car better driving properties, the turbocharger has been fine-tuned to provide high torque from low revs.


Lower fuel consumption
Fuel consumption and CO2 emissions (EU Combined) with automatic gearbox and start/stop is now down to:


S60 5,4 l/100 km 142 g/km

V60 5,7 l/100 km 149 g/km

V70 5,7 l/100 km 149 g/km

S80 5,6 l/100 km 148 g/km

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