vvt, cylinder deactivation etc.
vvt, cylinder deactivation etc.
(OP)
I am familiar with some of the types of VVT conceptually, but how are they really being implemented in production vehicles? Also what method are the manufacturers using to deactivate cylinders? It seems like you could just turn off injectors selectively but I'm guessing it is not that simple.





RE: vvt, cylinder deactivation etc.
DOD = displacement on demand or cylinder deactivation. In this case solinoids open the intake and exhaust valves in a sequence where exhaust gases are trapped in the cylinder and just recirculate.
RE: vvt, cylinder deactivation etc.
Most other manufacturers use a simple advance retard mechanism on the cam/s at the cam drive pulley and call it something like vtec, like vvtt or whatever.
Regards
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips Fora.
RE: vvt, cylinder deactivation etc.
DOD isn't quite as simple as just cutting fuel to the cylinder. Of course, that must be done, but there is also a valve control component as well. There are greater losses to be minimized by stopping the pumping action. So, the intake valve ceases to open, and the exhaust valve is always closed. Hence, no throughput of gasses.
It's much more efficient to let the piston compress the air, and then let the compressed air in turn push the piston back down. Work in = work out - frictional losses
By pumping air, less energy is conserved, and pumping losses (intake stroke and exhaust stroke) are added to frictional losses.
RE: vvt, cylinder deactivation etc.
RE: vvt, cylinder deactivation etc.
Regards
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips Fora.
RE: vvt, cylinder deactivation etc.