PDA

View Full Version : Valve Force



Pinter
02-03-2008, 01:47 PM
Hey guys, I'm doing some work on redesigning valve control but I'm a bit stumped. Does anyone know how much force it takes to open the valves during normal operation in a CBR?

Pinter
02-03-2008, 01:47 PM
Hey guys, I'm doing some work on redesigning valve control but I'm a bit stumped. Does anyone know how much force it takes to open the valves during normal operation in a CBR?

Chuckster
02-03-2008, 01:58 PM
How fast do want them to open? :->

Pinter
02-03-2008, 02:47 PM
well i am looking at modifying for electromagnetic valve control. it might be a bit aggressive but i would hope i could hit similar opening times to the normal mechanical operation, even say just at idle so 3000 rpm on the race engine. then ill address solenoid speed for 10 000rpm plus later. i want to get some base stuff down so that i can see if the concept works before taking it right up.

Chuckster
02-03-2008, 03:59 PM
You could look at cam profiles and weigh parts to get a feel for acceleration and valve/ mass to get a starting point. Digital video pics of a running engine may be the easy way to get some data. Be aware that your video sample rate may well alias the true action to a lower frequency.

My opinion is that you actually need to look at your max operating RPM first to see if you have any hope of success.
That will set your actuator size and power consumption.

You may not like how much electical power you need to supply!

This is an electrical/mechanical engineering control feedback systems exercise. Possibly someone in your robotics dept may be already be very familiar with this sort of problem and put it into perspective for you.

Kirk Feldkamp
02-03-2008, 04:10 PM
Yikes. Talk about getting off track for the purposes of FSAE!

If you're looking for a monster project to get yourself busy with, yes, that could be a good one. I've been involved with an electromagnetic valve actuation project before, and it's not even a remotely simple task. My advice if you're *really* wanting to do that project is to start with a single cylinder engine and get it working on that first. You're going to find that the packaging requirements probably dictate an entirely different top end geometry, which means making your own head.

For FSAE, there is absolutely no potential points gain at comp to be had from implementing that project. Think about it.

-Kirk

Pinter
02-04-2008, 01:14 PM
We are actually looking at doing it on a single cylinder engine made by honda with aspirations of proving the concept before working on the full size engine. I do greatly appreciate the feedback though and will consider your advice before investing too much into this.

drivetrainUW-Platt
02-04-2008, 01:49 PM
Are you going to run a 42v electric system on your fsae car for your valves?

Seems like quiiiite the project.

screwdriver
02-04-2008, 02:24 PM
If you're doing this, don't waste the effort, either try to sell it or at least do it as a final year project.

To answer your original question: I think, you should start by measuring the spring-rates of the valve springs.
That should give you an idea of the performance of your proposed actuator.