I'm planing on actuating a valve in the exhaust port using a linear actuator.
The distance traveled is roughly 4 cm and the frequency of actuating the valve is around 3300 times per minute. the linear actuator pushes down the valve and pushes it back up the approximate weight will be within 13-20 grm at maximum.
Any ideas for the actuator?
it would be nice if the actuator can handle high temperature also. ]
Nothing but a solenoid can go that fast I'd have thought....
4cm sinusoidal oscillation at 55Hz is an approx acceleration of 2000 m/s^2, which
with 20g mass needs 40N force, power levels are 360W or so in the absence of
return spring.
This is serious engineering.
yup this is serious engineering and if i dont get it done within a week or so my teachers will be serious ]
Is there a commercially available solenoid which can do this if so link me.
thanks MarkT
"Failure is merely recognition that a solution has yet to be found" 
That should ward him off
thanks for the reply 
If you want any kind of efficiency then a mechanically resonant system is required, with
a narrow frequency range and high Q value. Otherwise its a massive voice-coil style
actuator as used on washing-machine-sized disk drives of the 1960's...
MarkT:
If you want any kind of efficiency then a mechanically resonant system is required, with
a narrow frequency range and high Q value. Otherwise its a massive voice-coil style
actuator as used on washing-machine-sized disk drives of the 1960's...
I worked on those kinds of drives in the 70's performing field servicing of minicomputer systems. The drives were the size of a refrigerator with two large drawers containing the two drives. Voice coil magnets were the size men's shoe box with voice coils a good 6-8" in diameter. These actuators drove a tower with 20 magnetic pick-up heads that traversed the ten platter disk cartridges. A blank disk cost over $1,000 in 70s dollars, had maybe 50 megabyte capacity per drive.
Those that are old enough have seen a tremendous evolution in computer systems over the 45 years or so.
yup this is serious engineering and if i dont get it done within a week or so my teachers will be serious
Is there a commercially available solenoid which can do this if so link me.
The voice coil linear actuator that your teachers asked you to find on the net can be purchased, if you have $5,000-20,000 to spare. Seems like a silly assignment, but surely you have found companies like this one: Voice Coil Actuator - H2W Technologies
Possibly something in the realm of electronic fuel injectors might could be utilized.
But they are tiny little solenoids opening and closing little valves - not moving 4cm !
A diesel injector from a container ship's engine, maybe!
A diesel injector from a container ship's engine, maybe!
Those size engines only run maybe 450 rpm.
There is a good reason why, in 150 years of automobile engineering, nobody has driven an exhaust valve this way. It won't work.
If I had to solve this, I would get a regular electric motor which can be driven at 3300 rpm, connect a flywheel to it, a connecting rod, and then some kind of framework to constrain the end of the connecting rod to move in a linear fashion. If you look at a diagram of an 1850's ship propulsion steam engine, and then scale it down, and drive the flywheel with the electric motor, and then put your valve where the piston of the steam engine is, then you get the idea.
The reason I would do this, instead of a solenoid arrangement, is that the requirement to overcome the inertia of pushing your exhaust valve in, and then out again, is considerable and hard to control. Using a flywheel, evens out the power required to do this. Also, electric motors are available in any size and speed and controlling them is a well-handled problem.
The other thing to consider, is how you want your valve to open and shut.
An ideal exhaust valve is going to open and shut very quickly, compared to the time it spends open, and the time it spends shut. An ideal exhaust valve is going to have a position vs time sequence that looks as much like a square wave, as possible.
Whereas the reciprocating system I suggested is going to have a valve position versus time graph that looks more sinusoidal.
And a conventional linear actuator is going to look more like a triangular wave.
If the periodic cycle of your valve is about 18 milliseconds, and you want to open in in 2 ms, and keep it open for 7 ms, and then close it in 2 ms, and keep it closed for 7 ms, then you would actually be needing an acceleration in excess of 20000 ms/sec to actually shift the valve from one state to the other.
The other thing you need to ponder, is why most valve arrangements use a big spring to provide the movement in one direction.
If you don't know what desmodromic valves are, you can look them up on wikipedia. They don't seem to be very popular in the real world, but maybe right for you.
what if the initial requirements change and that now the lift is only 3.2 cm and the no of lifts per minute is 800 only. is it possible to lift this valve with a linear actuator ?
Is the "linear" set in stone? I mean, could some machine work be done to change the mechanism of exhaust from a linear valve to maybe rotary or slide (transverse linear)? I'm not sure how practical such things are when it comes to the frequency you need, just tossing it out there. The mechanical cam mechanism still reigns in this area for a reason.
Since the use of linear actuator is not feasible i have an other idea please tell me if this will work:
http://forum.arduino.cc/index.php?topic=224412.0
and the main reason for not using camshaft is that then professors will say that this is not much different from using an ordinary camshaft why do you need to electronically control it ?
Not that i care about what they say ]
It would be like not doing justice to my project that's all
any ways Thanks to all the awesome people who put up with my endless quires :*