I should qualify my last statement by adding that I'm talking about reducing lift from the possible maximum. Of course, the maximum lift can have a significant effect on engine behaviour.
Jean
Electronic valve control project
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GartnerProspect
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Re: Electronic valve control project
I really think the gains could be tremendous accross the power band given the ability to dynamically adjust lift and duration, independantly. It would open up an entirely new world of possibilities.
The dynamics inside an engine are so complex I can't even pretend to understand it even for a bit. I don't really think most people do have a firm grasp, honda engineers aside
After all, they were rocking 50mpg cars in the 80s. Most companies still can't do that today, though in their defense it has a lot more to do with emissions than technology...
I'd love to see completley programmable lift, duration and per-cylinder shut down. So somebody find the magic electronic actuators and get it done.
I had a dream last night about a linear actuator that worked like a stepper motor, with multiple steps to define a number of lifts very absolutely. Problem being, the total availible force would naturally be very low as the airgap would be huge, as well as the throw... Solenoids suck. The force curve is backwards from what is idea. We need a bizzaro solenoid.
The dynamics inside an engine are so complex I can't even pretend to understand it even for a bit. I don't really think most people do have a firm grasp, honda engineers aside
After all, they were rocking 50mpg cars in the 80s. Most companies still can't do that today, though in their defense it has a lot more to do with emissions than technology...I'd love to see completley programmable lift, duration and per-cylinder shut down. So somebody find the magic electronic actuators and get it done.
I had a dream last night about a linear actuator that worked like a stepper motor, with multiple steps to define a number of lifts very absolutely. Problem being, the total availible force would naturally be very low as the airgap would be huge, as well as the throw... Solenoids suck. The force curve is backwards from what is idea. We need a bizzaro solenoid.
Re: Electronic valve control project
i have no idea what the answer to that is.. I just sort of assumed that you would need variable lift to throttle back, but i suppose shortening the intake time should have the same effect.
another thing to consider is that partially opening the valve could let you maximize the opening time, where 100% open the cylinder would be too close.
i think you are right that just controlling the current may not be accurate enough.. will think about that some more. i originally just figured on a calibration table. maybe temperature compensating it would help? I would still like to avoid the added complexity of closed-loop control on the lift.
another thing to consider is that partially opening the valve could let you maximize the opening time, where 100% open the cylinder would be too close.
i think you are right that just controlling the current may not be accurate enough.. will think about that some more. i originally just figured on a calibration table. maybe temperature compensating it would help? I would still like to avoid the added complexity of closed-loop control on the lift.
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GartnerProspect
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Re: Electronic valve control project
Hmm... I get it!
It never clicked that with an e-camless system you could do away with the pesky throttle all together...
I can see the desire for variable lift now very clearly.
It never clicked that with an e-camless system you could do away with the pesky throttle all together...
I can see the desire for variable lift now very clearly.
Re: Electronic valve control project
I would at least try to see if you get good results from that before going to all the trouble of having variable lift. You can also deactivate cylinders if you really need to "throttle" back (which is actually the extreme of shortening the intake time).Wiglaf wrote:i have no idea what the answer to that is.. I just sort of assumed that you would need variable lift to throttle back, but i suppose shortening the intake time should have the same effect.
Jean
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shameem
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Re: Electronic valve control project
Instead of an electromagnetic actuator could a pneumatic muscle or a Nitinol based electric muscle be used as an actuator?
http://en.wikipedia.org/wiki/Pneumatic_ ... al_muscles
Also can a simple electro-hydraulic actuator be designed and used (the control signals are electric and hydraulic pressures are used to control the valves) - this has the advantage high power density with a low overhead....
http://en.wikipedia.org/wiki/Pneumatic_ ... al_muscles
Also can a simple electro-hydraulic actuator be designed and used (the control signals are electric and hydraulic pressures are used to control the valves) - this has the advantage high power density with a low overhead....
Re: Electronic valve control project
The electro-hydraulic is what I've seen used in the one commerical system out on the market. It does seem to be the easist method to help deal with power efficency and packaging requirements.
Re: Electronic valve control project
howdy, long time no post.
my main distraction is back on the road! aside from the other distractions, mainly the lemon race in about a month, I'm back on this.
I'm not found of pneumatic, it is very on/off, not controllable. hydraulic is definitely a possibility but would like to avoid the complication if possible. we will see.
my main distraction is back on the road! aside from the other distractions, mainly the lemon race in about a month, I'm back on this.
I'm not found of pneumatic, it is very on/off, not controllable. hydraulic is definitely a possibility but would like to avoid the complication if possible. we will see.
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shameem
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Re: Electronic valve control project
The electro hydraulic system would be very good powerwise but somewhat bad in terms of response speed. Also AFAIK systems dont exist for such "small" power requirements - so you cannot buy off the shelf components and customize - you will have to build one from scratch.
The pneumatic system would be a good starting point - especially when you can cannibalize a light impact wrench and basically have a pre-made valve driver - also pneumatic systems handle PWM schemes much better for positional control - not just on/off control.....
The pneumatic system would be a good starting point - especially when you can cannibalize a light impact wrench and basically have a pre-made valve driver - also pneumatic systems handle PWM schemes much better for positional control - not just on/off control.....
Re: Electronic valve control project
I don't have creditable references, but when I first started reading this thread, I was remembering some claims I've heard about tractor trailer trucks and trains. I've heard they use a hydraulic valve with electronic variation. Perhaps someone should go down to the local truck stop and start flipping those hoods open. Does anyone know of credible a reference for this?rsafier wrote:The electro-hydraulic is what I've seen used in the one commerical system out on the market. It does seem to be the easist method to help deal with power efficency and packaging requirements.