T_K

iTrader: (5)

I just went through the Nissan PDF explaining VVEL, and up until now I was under the impression that at least some part of the valvetrain still used a rotating camshaft. After looking through it, if I'm understanding it correctly, the DC motor just goes back and forth to open the valves, which also makes sense. A static rotating camshaft, would still have problems with controlling duration. Pretty nifty little feature, then I started to think, how fast the motor must have to oscillate back and forth to keep up with engine speed. I did some basic calculations using the 7500rpm redline, and the motor had to go back and forth over 60x per second, although I could have understood it all wrong, then the calculations would mean nil.

Anyone know any more about how the VVEL system works? I think I may be understanding the diagrams wrong. They are all just static pictures, so it's hard to really see how it works. From looking at the rocking nature of the entire valvetrain assembly based on the motor having to move the assembly back and forth by the bolt looking thing attached to it, it seems like there would be an upper RPM limit, where the motor just wouldn't be able to move back and forth fast enough.

TK

FAIRLADYZ_MANnE

iTrader: (2)

there needs to be more research done on the vvel system.

there is alota potential
shops, get to work on this engine

Hoooper

iTrader: (5)

A rocker arm and two types of links close the intake-valves by transferring the rotational movement of a drive shaft with an eccentric cam to the output cam. The movement of the output cam can be varied by rotating the control shaft within the DC motor and changing the fulcrums of the links. This makes a continuous adjustment of the valve lift amount possible. C-VTC and VVEL together control the valve phases and its valve events and lifts, allowing free-control of the valve timing and lift. This results in more efficient airflow through the cylinder and significantly improves responsiveness, optimizing the balance between power and environmental performance.

Credit: wikipedia

it seems that it does have a rotating camshaft. i think it operates something like a worm gear

T_K

iTrader: (5)

I attached the PDF file. Look at the operating diagram. Based on the connections from one device to another, the only thing that can rotate freely is the dc motor and the bolt that its attached to.

TK

EDIT: Nevermind the file is too large. Heres the link instead.

http://www.nissan-global.com/EN/DOCU...0713VVEL-e.pdf

Hoooper

iTrader: (5)

the dc motor drives the variable lift, but the cam itself is driven by the motor. the dc motor only turns the what looks like eccentric cam which makes the arms extend to increase lift from the lower cam? really hard to tell on those drawings. i read a really good article explaining it not too long ago but by now i have forgotten most of it

T_K

iTrader: (5)

The oscillating cam seems to be attached to link A and link B, which would make rotation impossible. Here's a pic:

http://www.motor-talk.de/images/News...4pix4hires.jpg

From that image, look at the shape of the lobe on the oscillating cam, based on that, if that was rotating, it would cause an abrupt closing of the valve.

TK

Hoooper

iTrader: (5)

The VVEL system
A rocker arm and two types of links close the intake-valves by transferring the rotational movement of a drive shaft with an eccentric cam to the output cam. The movement of the output cam can be varied by rotating the control shaft within the DC motor and changing the fulcrums
of the links. This makes a continuous adjustment of the valve lift amount possible.

Resolute

iTrader: (2)

The system has a camshaft driven by the timing chain, just as any other VQ engine. The difference lies in the profile and linkage. Where a DE or HR engine has a cam profile ground into the camshaft to determine valve lift and duration, the VVEL uses a DC motor to adjust the linkage acting on the valve from the camshaft input. The cams still activate when the valve is opened, hence the use of variable valve timing on the front of the camshaft like any other VQ engine. However, the cam is not profiled to have duration or lift characteristics, it is simply an eccentric cam that acts on the VVEL linkage. The cam lobe, which is simply a round eccentric cam, rotates inside the control shaft which is connected to the rocker arm. The rocker arm position is varied by the DC motor. Depending on where the rocker arm is positioned, the amount of lift is varied. As the cam rotates, the control shaft acts on the rocker arm, which in turn pushes down on the output cam and the valve lifter.

Will

Resolute

iTrader: (2)

It makes sense if you know that the cam rotates inside the control shaft (the big polished arm that connects to the rocker assembly)

Will

T_K

iTrader: (5)

Makes sense now. For some reason I had it drilled in my head that the polished cam didn't rotate. I kept focusing on the cam that was in contact with the valves. How does the system go about adjusting duration, or does it not vary that?

TK

Hoooper

iTrader: (5)

its gets more duration when the valve is at higher lift, but i dont think it can directly change duration ie: large duration at low lift and low duration at high lift

T_K

iTrader: (5)

So aside from higher lift generating longer duration due to the longer distance the valve has to travel to open and close, theres no adjustments of duration at a set lift?

TK

Hoooper

iTrader: (5)

dont think so. vvel is variable valve event and lift, with even being the cam advance and lift being lift obviously, so it seems that it doesnt have variable duration. not sure how one would even do that though (variable duration)

T_K

iTrader: (5)

120V battery and a really strong magnet. heh.

TK