Continous Variable Valve Lift

I like the single VANOS system on my Bimmer (325) - it, combined with the EFI, makes the car have a lot of smooth torque when just putting along, and still breathe nice on the top end. Not that car is a fire breather (186 HP), but it moves out fine for me, gets good gas mileage (30+ on the highway - sometimes in the high 30s if I slow down to about 70 MPH), and you can hardly stall it.

The double VANOS system (both exhaust and intake) is supposed to be even better.

I think totally electronic valve systems are probably the future - IIRC, both BMW and Mercedes have been working on those.

Ok 1000th post

what about off centre mounted rocker pin ends to do the variable bit and hydraulic lifters to take up the slack. then if the rockers were solid or curved at the ends and pushed bucket guided valve ends setup like the exhausts on a cough cough spit er um Rhonda cough it might work. the hydraulic lifters would need to be integrated into the bucket guides

it all gets complicated and heavy bah

there are some really fancy ways to make variable speed transmissions there has to be a simple way to do it for valves somewhere maybe in nature? there is an idea to be found somewhere

I like the Toyota thingy but its heavy as well. the BMW idea i need to see a pic

after a quick blast on my 700 though i think really that just more CCs can simply answer the power spread / available tourque and delivery issue. fuel ecomomy maybe not .......

bushmechanic said:

there are some really fancy ways to make variable speed transmissions there has to be a simple way to do it for valves somewhere maybe in nature? there is an idea to be found somewhere

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There is a guy (in ozland I think) who has come up with a 'revolutionary' transmission - not much more than a planetary transmission that uses electric motors to control planetary gears to engage other planetary gears. I've always like planetary gear transmissions; they are simple in concept (if not always in use), the gears are always in engagement and there are multiple points of engagement. They are usually compact and you can have multiple ratios from a single gearset depending on which gear you hold and which you let rotate.

I have often thought that if someone could just come up with an efficient and simple way to control which ratios are selected then a planetary transmission would be the future transmission. Maybe this guy has done that - but it isn't particularly 'revolutionary'.

I also think it would be nice to have the dual clutch/dual shaft gear system on a motorcycle. IIRC Honda has done this with their new VFR (which I like, but unfortunately I don't fit the bike).

pushrods are nice.. Ti is nice and light and the cam can be kept down low,

I have seen a cam, I forget where, maybe the patents sites

it was a 3D shape with a swivelling follower and the camshaft moved axially, as it comes accross it moves so the follower runs on a bigger section of the cam lobe.

heres one, not sure if that was it

searching for 3D cam on google shows a few more

another simple one

http://www.mechadyne-int.com/vva-media/ ... -animation

Smorgasbord said:

I like the dual clutch idea a lot, but it is like preemptive shifting in a way by using two gearboxes.

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Two clutches, two shafts, one gearbox. One clutch/shaft for odd gears, another shaft/clutch for even gears. One shaft runs inside the other - the outer being a quill shaft. Electronics control the shifting such that the right gear for the next engagement is selected based on your RPM, throttle, speed and current gear selection. As one gear is disengaged the other is smoothly engaged. From what I have read and heard from people who have driven the cars, it is very smooth. Would be good for a street bike, maybe for a dirt bike - you could shift with a pushbutton on the handlebars (you can now with certain kits, but it isn't the same).

In a way, it amazes me that we are still using basically the same tech that we used 100 years ago in motor vehicles; reciprocating piston engines with poppet valves and multiple shaft transmissions.

The future is probably electric bikes with a compound wound motors controlled by computers.

CodeMonkey said:

Two clutches, two shafts, one gearbox. One clutch/shaft for odd gears, another shaft/clutch for even gears. One shaft runs inside the other - the outer being a quill shaft. Electronics control the shifting such that the right gear for the next engagement is selected based on your RPM, throttle, speed and current gear selection. As one gear is disengaged the other is smoothly engaged. From what I have read and heard from people who have driven the cars, it is very smooth.

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My car has it (Dual Shift Gearbox), and it works well most of the time with very quick smooth changes. I think it's fitted to my car more for the speed of the changes so that acceleration is hardly interrupted at all during an up change, but that means it is smooth too. You can catch it out if you have to change gear the other way to what it's expecting, so it now has the wrong gear preselected on the disengaged clutch and has to change to the right gear first. It still works but it takes a bit longer to change. You can shortcut that by using the paddles on the steering wheel to ask for the new gear as soon as you know you need it rather than waiting till the computer works it out.

Smorgasbord said:

Maybe with a dual clutch gearbox, but with dogs and constant gear engagement, that bit like in a normal motorcycle not having to wait for synchronization, maybe the unexpected direction gear changes would be a lot faster so that you would never really be able to tell the difference? Except from the differnt "clonk".
Edit: And that clonk would not be that bad since the clonking dog would not be under load until the dual clutch switches over.

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I don't know enough about how that would work to know for sure, but I think the only time I really notice the delay on mine is when it's in normal mode, as it shifts up real early (presumably for fuel economy) so you can be accelerating gently and find it's in 6th gear by the time you get to around 40mph. If you then floor it, the brain works out that you probably want to be in 2nd or 3rd so it has to change down through multiple gears and possibly from an odd gear to an odd gear or even to even (e.g. 6th to 4th or 2nd), so I guess it needs to use the same clutch it's already using and for that change you lose the advantage of having two clutches, plus it has to rev the engine up quite a lot to match the speed. Doesn't happen in sport mode as it tends to hang onto each gear for much longer during acceleration so you're never 3 or 4 gears too high for a quick burst of acceleration. All this is just down to the software the brain's running to make decisions, so it wouldn't be hard to tailor that to suit a different driving/riding style or have more than two modes available.

Or you can just switch into manual and use the paddles to pretend you're an F1 driver. :mrgreen:

Smorgasbord said:

And yes, that would be a desirable thing in a competition motorcycle too where each gear change means giving a little away each time.

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I know with mine the 0-60mph time is faster on the DSG model than it is on the same model with a manual (stick shift) gearbox. That wouldn't be true for most traditional automatics where there was usually a performance penalty. Also the smooth fast changes and almost no interruption to the power are good for handling - probably would be even more so on a bike as the loading on the suspension would be constant (similar to what a quick-shifter can do for you I guess).

On mine you can use the "F1" paddles at any time and it switches into manual mode automatically and if you don't do another manual change it stays there for something like 30 seconds then drops back into full auto. Handy if you know you need to be in a different gear for a particular corner or the like. You can select manual on the gear selector of course and it then stays in whatever gear you select with the paddles, or you can push the gear selector backwards and forwards to change up and down, like a sequential box. Oh no, too many choices - I'm getting confused...