25 October 2011

Mazda announced it will progressively introduce clean diesel vehicles to the Japanese market, beginning with the new Mazda CX-5 crossover SUV in spring 2012. The vehicle—powered by Mazda’s next-generation SKYACTIV-D 2.2 liter diesel engine—will be showcased at the 42nd Tokyo Motor Show in December.

The SKYACTIV-D 2.2 is the world’s first passenger vehicle diesel engine to meet Japan’s 2009 emission standards (“Post New Long-Term Emissions Regulations”) without NOx aftertreatment. SKYACTIV-D diesel engines will also meet Euro 6 and US Tier 2 Bin 5 emission regulations without NOx aftertreatment, said Mazda. A particulate filter is expected to be used for PM emission control.

The CX-5 delivers 129 kW (173 hp) of power, maximum torque of 420 Nm—more than some 4.0 liter V6 gasoline engine vehicles—and the best fuel economy of any SUV on the Japanese market at 18.6 km/L = 5.38 L/100 km = 43.8 mpg (JC08 cycle; front wheel drive, automatic transmission models).

The SKYACTIV-D diesel engine technology features a low compression ratio of 14:1 for NOx and PM emission control via optimized combustion timing. The low compression ratio also allowed for a 25 kg engine weight reduction (compared to the current Mazda diesel) thanks to the use of an aluminum cylinder block, thinner cylinder head walls and lighter pistons. The engine utilizes multi-hole piezo injectors capable of up to nine injection events per cycle. Variable valve actuation (VVA) is used for rapid engine warm-up, to recirculate some of the hot exhaust gas into the intake port to increase the air temperature. The engine also uses a two-stage turbocharger.

The CX-5 is fitted with a six-speed automatic SKYACTIV-DRIVE transmission. A redeveloped idling stop system, i-stop, is used with the SKYACTIV-D 2.2 engine. Unlike other diesel engine stop-start systems that require two engine cycles to restart combustion, i-stop restarts in a single cycle by careful positioning of the pistons as the engine stops. At less than 0.4 s, i-stop achieves the world’s fastest diesel engine restart time, according to Mazda.

While diesel cars have been uncommon in the Japanese market, Mazda expects to have a competitive advantage by avoiding the expensive NOx aftertreatment system. The vehicle is promoted based on the high torque (approximately twice as much as similar sized gasoline vehicles), as well as on the price advantage of diesel fuel over gasoline and 30% better fuel economy. With these advantages, Mazda expects that its clean diesel vehicles will become a core part of its product lineup in Japan.

At the Tokyo Motor Show, Mazda will also present the TAKERI midsize sedan concept powered by a SKYACTIV-D diesel engine, as well as several new SKYACTIV-G gasoline models, including Mazda Denio and Axela. The compact Demio is powered by the SKYACTIV-G 1.3 liter engine which delivers a fuel economy of 25 km/L = 4 L/100 km = 59 mpg (JC08). The Axela features the SKYACTIV-G 2.0 engine, with a fuel economy of 17.5 km/L = 5.68 L/100 km = 41.4 mpg (JC08).

Source: Mazda (SKYACTIV-D Engine)