I have to be a bit skeptical of this. Sure it may do well from a
mechanical standpoint, but what about airflow? I can't see how you can get
the airflow you want from air trying to make it through a spinning ball
like that. That means the air would basically be spinning as it entered
the combustion chamber, and would be aimed at different points as the ball
spins. Maybe good for some engines, but not a lot... I know our Winston
Cup engines like nice laminar airflow. You would have to be able to draw
the air through the ball in a very tiny amount of time, even tinier as the
revs go up. I just don't see that happening. Also, how do you seal
against combustion chamber pressure with a spinning ball? Even if you got
the mating surfaces between the ball and the head nice and smooth with very
small clearances, you have to have clearance for oil, which lets out
cylinder pressure. And remember it will change temperatures rapidly as
well, and will have a large temperature gradient in the ball itself. Also,
how would you oil it to keep the oil out of the combustion chamber?
-Matt
>Date: Fri, 22 Aug 2003 08:25:38 -0700
>From: "Mike Clements" <mikec@actional.com>
>Subject: interesting cylinder head design
>
>Anyone ever heard of this before? Looks really cool to me.
>
>http://www.coatesengine.com/eGallery/pages/RotaryValveSystem.htm
>
>As I understand the picture, there's a hole in the top of the combustion
>chamber. You stick a ball over the hole. The ball has channels bored into
>its circumferance. The ball spins around on the overhead camshaft. As the
>ball spins around, it alternately seals the chamber or the channels line
>up and it allows mixture in (for the intake ball) or exhaust out (for the
>exhaust ball).
>
>So the "valve" is just a ball spinning around. No springs, no lifters, no
>back and forth motion of any kind. You still have dual overhead chain
>driven cams, but with no springs and no back & forth motion, there is
>almost no resistance at all and almost no limit to how fast it can spin.
>
>Plus you get to set the valve timing / duration / lift any way you want
>with none of the current limitations about hitting the pistons on a high
>compression engine, or about getting enough lift at high RPM without valve
>float.
>
>They claim some impressive improvements to power output and lower
>emissions. They're talking about doubling the engine's RPM range. Of
>course you'd have to modify the intake, ignition etc. to handle the revs
>and use a big differential ratio but basically what they're saying is that
>the revs will no longer be mechanically limited by the valvetrain, and the
>valvetrain will have almost no mechanical losses.
>
>Neat stuff!
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