Electronic Valves?
01-15-2003, 10:33 AM
#31
Racer
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"Wasn't there someone experimenting with rotary valves? "
I believe Yamaha uses them in thier 125 and 250 GP 2 strokes.
"Stop at the stop light and the engine will shut down. tap the gas pedal and off you go with instant start"
Honda already has this in the Civic Hybrid and the Insight. It's actually kinda cool. You turn the key and the engine is just running, no start, just running and when you come to a stop it's just off, step on the gas and it's running again. Pretty neat stuff.
doyle
I believe Yamaha uses them in thier 125 and 250 GP 2 strokes.
"Stop at the stop light and the engine will shut down. tap the gas pedal and off you go with instant start"
Honda already has this in the Civic Hybrid and the Insight. It's actually kinda cool. You turn the key and the engine is just running, no start, just running and when you come to a stop it's just off, step on the gas and it's running again. Pretty neat stuff.
doyle
01-16-2003, 09:33 AM
#32
Instructor
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One things to remember here is that when you have a mass (the valve) connected to a spring (the valve spring) the natural frequency of the system is the square root of K/M where K is the spring rate and M is the mass. You start to get problems when the freqency that the cams are turning approaches the natural frequency of the valve system. You can play a couple of dirty tricks by using two springs with different spring rates on each valve, but that only helps so much. Obviously, if you want a fast spinning engine and you've already reduced M as much as you can, you need a spring with a big K value. This means that the forces imparted by the spring will be huge, causeing all kinds of engineering challenges.
Tom
Tom
01-16-2003, 12:30 PM
#33
Drifting
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The problem with most of the hydraulic/pneumatic operated valve systems has been the transfer time between stopping the opening valve, and then getting it to close quickly because of the need to reverse the gas/air flow direction. Hence the reason that most of the systems still use a spring to close the valve. The systems just open the valve, and then shut off, allowing the spring to close it.
An electrical system SHOULD overcome that as the time taken to reverse/divert electrical charge is almost instantaneous. As I said though, the problem with the electronic valve so far,has been that is unreliable. This is mostly down to the physical exerts demanded on it by revving upto 15000rpm. Once a more rugged valve becomes available, then watch this space!
An electrical system
An electrical system SHOULD overcome that as the time taken to reverse/divert electrical charge is almost instantaneous. As I said though, the problem with the electronic valve so far,has been that is unreliable. This is mostly down to the physical exerts demanded on it by revving upto 15000rpm. Once a more rugged valve becomes available, then watch this space!
An electrical system
01-16-2003, 07:38 PM
#34
Burning Brakes
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i think electronic valve actuation sounds like a really cool thing. less mechanical parts is a good thing in my book.
one thing that would be very important would be redundancy. you would need duplicates of the computers that control the valves and really good quality wiring for both. if you didn't have this and the computer went down or shorted out and blew a fuse, it'd be the same thing as our timing belt breaking cause nothing would be moving the valves anymore.
one thing that would be very important would be redundancy. you would need duplicates of the computers that control the valves and really good quality wiring for both. if you didn't have this and the computer went down or shorted out and blew a fuse, it'd be the same thing as our timing belt breaking cause nothing would be moving the valves anymore.
01-16-2003, 09:09 PM
#35
Drifting
Thread Starter
</font><blockquote><font size="1" face="Verdana,Tahoma,Arial,Helvetica,Geneva">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Originally posted by dualblade:
<strong>i think electronic valve actuation sounds like a really cool thing. less mechanical parts is a good thing in my book.
one thing that would be very important would be redundancy. you would need duplicates of the computers that control the valves and really good quality wiring for both. if you didn't have this and the computer went down or shorted out and blew a fuse, it'd be the same thing as our timing belt breaking cause nothing would be moving the valves anymore.</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Not if you had the valves default to close (i.e.: no power = closed). Or if there is a sudden power failure there will be no force keeping them from being forced closed by the piston (no camshaft in the way), so you would be less likely to see bent valves.
<strong>i think electronic valve actuation sounds like a really cool thing. less mechanical parts is a good thing in my book.
one thing that would be very important would be redundancy. you would need duplicates of the computers that control the valves and really good quality wiring for both. if you didn't have this and the computer went down or shorted out and blew a fuse, it'd be the same thing as our timing belt breaking cause nothing would be moving the valves anymore.</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Not if you had the valves default to close (i.e.: no power = closed). Or if there is a sudden power failure there will be no force keeping them from being forced closed by the piston (no camshaft in the way), so you would be less likely to see bent valves.
