Most of my nights lately are spent researching this damn project we have to do to graduate, it basically demands a hefty portion of everything we've learned or at least been introduced to in the past 4 years. Basically we have to come up with an invention/innovation that is within the realm of possibility but not necessarily probability. I've messed around cars a bit to know how they work so I toyed around with the idea of combining what I've learned in CNC classes, robotics, materials science, with what I know about cars.
Ultimately I came up with a few crazy things but finally settled on (and now stuck with lol) this plan: Ball-screw actuated valve train system.
If you don't know what ball screws are, they are basically the precision drivelines of linear CNC machines, they are a precision engineered screw that are used in conjunction with stepper motors to get the super accurate linear travel cnc machines are capable of...something like .0001" is not out of the question at all.

A company does indeed make ball screws with diameters as small as 3mm. My design works best with 4v per cylinder, 1 ball screw for every 2 valves with a bridge in the middle linking the 2 valves. Unfortunately this would likely be really expensive but if it was programmed correctly you could essentially have an infinite combination of "cam swaps" possible with a few quick programming strokes, possibly pre-defined from the factory like "towing, performance, economy..." It would also eliminate a lot of moving parts and lighten up the engine a bit.
Does it seem a bit far fetched?
I think this course is flawed in general because any such crazy innovation/invention someone can come up with it's nowhere near as good as it could be without collaboration...ie teamwork but alas it's what I gotta do. Please criticize away, I love hearing different opinions about this stuff.

for the too long didn't read people...yer lazy lol

 

If the ball screw system is so fine and accurate ... how would heat affect it??

Jules

 

prepare yourself for some funny terms...
the ball screw, the *****, and the nut are all made of 400 series stainless steel. temperatures at the exhaust valve(the hotter one of course) average between 140*C to 250*C...

Quote:

Steinmeyer ballscrews are also available in corrosion resistant steel. High temperatures (up to 300° C), as well as anti-magnetic properties, can be handled using copper-beryllium

 

The only thing I see is bulk, cost and complexity ... so yes, possible but not probable??

Also with that sort of complex and high precision mechanism, contamination and dirt particles would be an issue ... oil changes would be far more critical/crucial ..yes??

Jules

 

neat thing about ball screws is they use grease and require a lot less fluid changing. cost and complexity...I hear ya, that's the 1 big constraint this idea has against it

 

Thats the thing with engineering, almost anything is possible ... but all comes down to cost and complexity in the end ... I do think you are thinking outside the box though which is good :-)

Jules

 

There are quite a few VVT systems out there now too ..different manufacturers doing it their own way ... eg Honda VTEC systems

Jules

 

Heres a simple idea using a ball screw mechanism to alter valve lift for instance

 

how do you figure it would lighten it up..stepper or servo motors are heavy......you are talking 2-4 motors per cylinder and any kind of electric motor detests heat.....and like you said ..it would be stupid expensive.

also to get the timing speed you would have to have extremely low helix ballscrews and very high speed motors.....servo motors would be far superior over stepper

concept is interesting ........possibly similar to the Ducatti Desmo valve system....using a cam to open the valve...and another to close it.....eliminating the need for aspring.....thus eliminating valve float and valve lag

 

Thats kinda what I was wondering too ..the wholel thing would just be too bulky to be viable .. possible but just not viable ..

Jules