Daf diesel technology
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• Dutch truck manufacturer Daf has been talking about its future engine plans which could Lead to radical changes to its existing 11.6-litre diesel.
Technology options under review by Daf at its Eindhoven headquarters include the adoption of significantly higher injection pressures; compound turbocharging with a variable blade primary turbine; an overhead camshaft driving the fuel injection equipment; and highly modified pistons with the skirt cut away below the ring pack. Work is also being carried out on a four-valve-per cylinder layout and particulate filters.
Speaking on the company's stand at the Brussels Show, Hans Staals. product planning manager marketing and sales, told CM that the company is also looking hard at ways of creating the optimum fuel/air swirl in the combustion chamber. Rather than use the intake port to create sufficient swirl Daf is considering using a revised piston head construction to squeeze the incoming air into the required swirl pattern which then has the fuel injected into it at high pressure.
"We don't want to disturb the air in the intake phase, we want to get it into the chamber as smoothly as possible," says Staals.
A number of the proposed engineering options were featured on the company's stand along with a cutaway drawing showing them combined into one engine.
However, Staals says that rather than launch all the improvements at the same time, Daf will have a rolling programme of testing and iniplementalion with the most advanced engine coming on to the market by the mid-1990s — although parts of it could appear earlier.
The piston design and fuel injection system — which could feature variable injection timing — will be among the first to be changed.
"The moment we can transfer the technology into the engine we will do it," says Staals, who reports that the completed power unit will be very different from the existing 11.6litre engine.
Although Daf is looking at compound turbocharging, according to Staals it is by no means committed to the twin turbine philosophy already adopted by Scania.
Some of the new Daf hardware is already being evaluated, either on single cylinder test engines or on existing 11.6-litre straight six diesels.