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Variable valve timing is simple

 Rock the follower for simple VVT that is robust
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Real VVT can be robust. Consider a 4 cylinder twin cam 4 valve per cylinder engine. Enclose each portion of the cam (4 per cam) in a thick tube mounted on bearings on the cam or the cam supports. Bore two large holes in the side of the tube to house the cam followers (sliding with radiused outer surface). Lock the tube in place and the engine can run as normal. Rock the tube back and forth by +/- 10 degrees in phase with the cam. A change in valve period of plus 40 crank angle degrees (a bit less in practice) is achieved. Reverse the phase of the rocking, and a change in valve period of minus 40 crank angle degrees is achieved. Vary the phase and amplitude of the rocking for total valve timing control. You have turbo boost control, engine braking control, emissions optimisation, boy racer or granny mode option. No large forces are seen by the adjusting mechanism or oscillating drive. Why do the manufacturers persist with all their whacky half effective solutions? Because they would have no further developments to sell.
—MeWeBe, Apr 24 2007

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       So are you trying to move the lifter assembly back and forth a few thousand times a minute, essentially having the lifter follow the cam peak on its rotation? If so, that's a lot of motion and a lot of mass. I doubt it will feasible.   

       If your goal was to alter the cam timing, I suppose this could work, but the systems thay have for this now are just as good or better.
—Hunter79764, Apr 24 2007
   

       Haven't you just moved the complexity to another system? It now needs to be capable of oscillating precisely, at up to 3,500-4000rpm (half crank speed).   

       Also, can you provide a diagram to show how you are managing to alter the behaviour of the valves without the valve springs exerting any forces on the mechanism?   

       (On a separate note, the "big manufacturers are all conspiring against us" tends, to my limited mind at least, to make people seem a bit wide-eyed-zealot-ish... I wouldn't presume to meddle with your personal opinions, but I might suggest that you'd be better received without it. Up to you.)
—david_scothern, Apr 24 2007
   

       Not stupid, so much as overly focussed. And as for whom - well, THEM, of course? Can't you see? They're all around us. You'll see them when you look. Are you one of them?
—david_scothern, Apr 24 2007
   


 

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