I wonder why they couldn't simplify this with a solid round cam lobe with a machined groove in the side of it. Then a single rocker arm could have a roller bearing on the side of it to follow the groove.

__________________
1985 380SE Blue/Blue - 230,000 miles
2012 Subaru Forester 5-speed
2005 Toyota Sienna
2004 Chrysler Sebring convertible
1999 Toyota Tacoma

The cam and rocker arms both open and close the valve, by pushing it open and pushing it closed. There is a nice animation here:

http://www.ducatidesmo.com/valves.htm

This push/push arrangement allows very high valve speeds without the "float" associated with valve inertia and resonant spring frequencies

we campaigned a ducati in road racing - super twins its a 175 MPH class and the the system is very very simple with never any breakage cam related, engine speed of 9500 is what they max at road racing

many race shops have tried to reinvent the wheel with no luck the key is it is simple, and requies no effort of parts having 2 small rubber belts that are used to drive the set up its all light weight and offers no resistance to motion or engine movement, power than depends on how can you pump in and out with negative wave technology -- yes - jz

I think the Jag version of the stratified charge was called the 'Fireball'. I remember seeing some press release on it.

It looked like it would work and defete Honda's patent, but I don't know enough about the make to comment on if it worked as it should (to reduce emmisions and increase fuel economy) or not.

Interesting but I'm still curious: what holds the exhaust valve shut during the intake stroke? It would be at least relatively and partially a vacuum in the cylinder while air is being drawn in through the intake. The exhaust valves would want to come open at that time unless restrained. During the other 3 strokes, I can imagine that compression would hold the intake valves (exhaust valves too, come to think of it) shut as the pressure in the cylinder is going to be somewhat greater than atmospheric pressure and probably the pressure in the exhaust manifold.
Oh. Well. Makes my question of how they keep the valve closed a bit silly. That mostly on, temporarily off lobe - looks like about 240 degrees of closed - is of course keeping them closed until wanted open.

__________________
1986 300SDL, 362K
1984 300D, 138K

Cool. 1912 it says. I'm wondering if higher rpms made it unworkable. Would be pretty demanding I'd think. Hot gasses and all.

When I was thinking rotary for the electronic brain controlled valve gear I was thinking 90 degrees of motion, back and forth, a solenoid to operate both movements. Somehow my gut tells me that the mechanism to pull that off would be highly stressed. Would be difficult to pull off with any reliability.

__________________
1986 300SDL, 362K
1984 300D, 138K

The cam lobs hold the valves shut when they need to be closed.

The problem with valve springs is they float above a certian RPM, with that set up you can run an engine up to 20k rpm without any valve float. I think their new road bike redlines around 18k!


Mercedes breifly flirted with a valve design like this before the war, its actualy a very old design. Ducati just put the effort into perfecting it.

__________________
1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

Coats did some work with spherical rotary valves, but I don't know where it really went:
http://www.coatesengine.com/

The original 7.3 PSD was supposed to be camless, but there was too much trouble with it, mostly while starting. As it is, that engine was the first automotive application of a HEUI engine, it came out in 94. The valve control was supposed to be similar, with a high pressure oil pump filling a galley and solenoid valves applying that pressure to the valves to open them when the computer said to. There's so much power potential in a system like that, I can only imagine have a butter smooth idle, phenomenal torque, and power clear to the redline all from the same engine.