Volkswagen to implement cylinder deactivation in 4-cylinder 1.4 TSI engines in 2012

Volkswagen will debut cylinder deactivation (cylinder shut-off) technology in the new 1.4-liter TSI turbocharged, direct-injection engine beginning in 2012. Volkswagen is the first carmaker to implement this technology in a turbocharged four-cylinder engine in large-scale production.

The primary goal of the system is to reduce significantly fuel consumption by temporarily shutting off two of the four cylinders (cylinders 2 and 3) during low to mid loads; Volkswagen says that cylinder shut-off reduces fuel consumption of the 1.4 TSI by 0.4 liter per 100 km in the NEDC driving cycle. When the Stop/Start functionality is integrated, which deactivates the engine in neutral gear, the savings effect adds up to about 0.6 liter per 100 km.

The greatest benefits of the technology are realized while driving at constant moderate speeds. At 50 km/h (31 mph), in third or fourth gear, savings amount to nearly one liter per 100 km. Even when running on two cylinders, the 1.4 TSI—with its excellent engine balance—is still very quiet and low in vibration, Volkswagen says.

Cylinder shut-off is active whenever the engine speed of the 1.4 TSI is between 1,400 and 4,000 rpm and its torque is between 25 and 75 N·m (18–55 lb-ft). This applies to nearly 70% of the driving distance in the EU fuel economy driving cycle. As soon as the driver presses the accelerator pedal sufficiently hard, cylinders 2 and 3 are reactivated unnoticed.

Under the deactivation process, the combustion chambers are filled with air—this entrapped fresh air leads to minimal cylinder pressure and therefore to lower energy consumption. Afterwards, the system closes the intake and exhaust valves of cylinders 2 and 3; engine ignition only occurs once per crankshaft revolution. The pistons of the deactivated cylinder are now dragged by the crankshaft. On the other hand, efficiency increases in the two active cylinders, because their operating points are shifted to higher loads.

The valves are closed using a complex set of actuators: on both the intake camshaft and the exhaust camshaft, there are two adjustable sleeves (cam pieces) that are placed on special tooth systems. They are responsible for the eight valves of the second and third cylinders. At the ends of each cam piece, there are two different profiles adjacent to one another: a conventional full profile and a so-called zero-lift cam. The full profiles actuate the roller cam followers, which in turn actuate the valves in four-cylinder operation; that is, they behave like very conventional cams. However, the zero-lift cams rotate over the followers—i.e. they do not actuate them—and the valve springs hold the valves shut. Engine management simultaneously shuts off fuel injection.

Spiral-shaped slots are milled in the outer surfaces of the rotating cam pieces; these slots permit shifting the sleeves a few millimeters along the shafts very quickly; when electromagnetic actuators in the valve cover get a signal from the engine controller, two integrated metal pins engage the slots from outside and move them to their end positions. Finally, the cam pieces are locked in place by spring-loaded balls. As soon as the driver presses the accelerator pedal sufficiently, cylinders 2 and 3 are reactivated.

All mechanical switch-over processes are executed within one-half camshaft revolution; they last between 13 and 36 milliseconds, depending on engine speed. These processes are smoothed by accompanying interventions in ignition and throttle valve control.

Volkswagen utilizes information from the gas pedal sensor to detect the driver’s mode of driving. If the driving exhibits a non-uniform pattern—e.g. while driving in roundabout traffic or in a sporty style on a country road—shut-off functionality is suppressed.

The components for cylinder shut-off weigh a total of just over 3 kilograms. Their actuators, the camshafts and their bearing carriers are integrated in the valve cover. Two roller bearings reduce the friction of the shafts.

mmm interesting stuff! should have the same power as the twincharger, but much better fuel economy and emmisions! is this confirmation of the death of the twincharger engine too?

I understand the concept, but not sure how it works in the above.

realistically the valves need to stay open while the deactivated cylinder is on its compression stroke to minimise losses.. the current prius has something similar going on in its engine, where the intake valves are still open at the start of the compression stroke to reduce the energy taken to compress the intake charge - called the atkinson cycle.

although with a turbo in the mix too i guess it would have to be one of those twin-port types to avoid loosing pressure in the exhaust manifold.

of course the above means itll need a f**K heavy flywheel to keep NVH low - the days of responsive revvy engines are gone :(

Sounds great. Yet expensive if goes wrong out of warranty....

Hard to tell from the state ment if this is only going to be applied to the lower power turbo only 1.4 or all of the 1.4 including the twin charge version.

The only way to replace the twincharger is a Variable vane turbo which there is no mention of. Everone keep saying the twincharge engine is going out of production but I've still not seen any real evidence

Bearing in mind that they have trouble getting Exhaust Gas Recirculation valves or Euro 4 throttle dampening to work properly, yet another thing to go wrong.

Nick

Hard to tell from the state ment if this is only going to be applied to the lower power turbo only 1.4 or all of the 1.4 including the twin charge version.

The only way to replace the twincharger is a Variable vane turbo which there is no mention of. Everone keep saying the twincharge engine is going out of production but I've still not seen any real evidence

This x1000

This shows the engine will be around for a while yet

What happens to any small amount of engine oil that escapes past the rings - can this build-up and then burn when the cyls. are firing normally leading to excessive coking of valve stems etc ? Engine might be fine for a long time and then after considerable mileage might be "smoky" ( MOT failure). Can this feature be turned-off ? Does the engne provide engine braking going down hill ? I'm sure VAG has considered all these questions but this mechanism does sound a little complicated and with yet another ECU aspect to control. The metalurgical control ( hardness, toughness etc) of the added parts would need to be perfect.VAG have made a few mistakes in the past in this area ( simple oil pump drives etc). Look what happened to Toyota with the early VVT mechanisms. I seem to remember some American V8s that could be switched to 4 cyl. operation a long time ago - what happened to them ? I also seem to remember that VAG announced a new factory to be built in Wales to produce the PD injectors - the injectors were put into production about 10 years later !

Would take a brave man to order 1st production model !

I would imagine the re-sale value would plumet after the warranty expired until reliabilty was proven.

Edited 3 September, 201114 yr by vwcabriolet1971

Looks like a lot of VAG engines will get this the new S6, 7 and 8 all feature a V8 which can switch to 4 cylinder mode maybe as a test bed but does sound very interesting. Think Mercedes will be annoyed as I read somewhere they planned to be the first to have this technology in mainstream car ranges starting with s-class. Wonder if the Bugatti's will get this technology lol. Also could they put it onto diesel engines?

Looks like a lot of VAG engines will get this the new S6, 7 and 8 all feature a V8 which can switch to 4 cylinder mode maybe as a test bed but does sound very interesting. Think Mercedes will be annoyed as I read somewhere they planned to be the first to have this technology in mainstream car ranges starting with s-class. Wonder if the Bugatti's will get this technology lol. Also could they put it onto diesel engines?

Bugatti Veyron would benefit more than most cars. It is the demand for CO2 improvements that is partly driving this more than actual fuel consumption.

EU demanded each car producer lowered the average CO2 to 120 g/km or so hence Aston Martin giving away a reworked Toyota Aygo thing with each supercar.

There is some improvements on the diesels being launched at Franfurt that can improve fuel consumption on the diesel by a few grams of CO2 and an mpg or 2. Also the 7 speed wet DSG, DQ500, and at some point a move to 8 speed boxes like the other prestige manufacturers are using will further reduce CO2 and consumption as well as dropping cylinders.

You actually only need one cylinder running as to run at 70 mph you only need about 15Kw / 20hp. Twice the speed takes roughly 8 times the power. My car 160 hp = 140 mph , 70 mph = 20 hp, each cylinder capable of 40 hp but I imagine temperature gradients come in to it and it is best to have outer cylinder running and the inner cylinders snuggled between them receiving conducted heat.

Edited 4 September, 201114 yr by lol

There was a big american car on Fifth Gear (Chrysler 300C i think) that had this technology years ago. Maybe not a turbo, but its still had the tech.

Yeah forgot about the Chrysler hemi engines not sure they were all that clean or economical though. Your right about combining it with ever sophisticated auto boxes maybe it would be most economical on a 3cylinder engine which reduces the friction and would be balanced when running on 2 cylinders but allow for better acceleration when on all cylinders could combine it with direct injection and turbo charging?