Camless engines

[adsm08]

Yes, might need pre-heater to get gas vapor on cold days and then open the other cylinders exhaust valves slightly at this time so no compression resistance in crank, just might work

All very true. But who cares? With the system in question that would all be EXTREMELY possible.

Also, if you use large solenoids you could eliminated the valve, the valve seal, and it would be 150% non-interference.

 

[RonD]

Well valves are a pretty hardy and cheap solution to seal and survive the explosions inside cylinders.
It is just their timing that could be improved.

Not sure solenoids could survive that, quite a bit of explosive pressure pushing up on the valves when cylinder fires.
The "open in" valve design is like an "open out" door, very very hard to kick one of those doors in, lol.

Direct Fuel injection does have it's own set of issues by being IN the combustion chamber.

There is a patent for rotating "valves" in the head.
Basically a wheel/cylinder with a hole thru it
Same setup for timing and alignment as a cam shaft, but wheel rotates to allow air in and then seals for firing as hole rotates past cylinder
Could use same wheel for exhaust with second hole drilled thru at different location, wider wheel, or just use a second shaft.

Not sure how well that would hold up as carbon builds up, rotating should scrape it clean I guess, like rings do with cylinder walls.
Interesting idea I thought

But doesn't change valve timing possibilities afforded by the camless design

 

[don4331]

You're just talking camshaft-less poppet valved engine; cam-less engines have been around for ?100 years - Charles Knight patented the sleeve valve in 1908. And by correctly positioning ports on sleeve, one sleeve will provide both intake and exhaust.* But as Ron alludes, it doesn't provide the endless possibilities of camshaft-less design.

In order to start, engine needs air under compression and fuel as vapour (not liquid). Rings don't seal tight enough to maintain compression indefinitely and fuel will condense on cylinder walls/head/piston, so you can't get stopped engine to start without a little assistance. So, you still need a starter motor. But because you could hold valves open on all but one cylinder, the starter could be much smaller (motorcycle sized).

And you can flow the exhaust from that one cylinder into remaining cylinders, quickly heating them to operating temperature - minimizing cold start emissions (EGR on steroids).

The first challenge is getting rid of the valve springs: Renault's pneumatic valves work fine in racing engines but don't have the longevity to work in consumer automobiles. Until we see pneumatic valves in a production engine, doing the whole camshaft-less is probably too risky for an automotive manufacture. (Until we see a pneumatic valve consumer motorcycle, it still vapourware to me).

The historic problem with camshaft-less poppet valves - the power to run the hydraulic/pneumatic system was enormous (10X the power to run a camshaft). So, while it improved performance and was OK for racing engines where using 10hp to drive valves for 50hp to wheels was acceptable; it wasn't OK for where the 10hp to drive the valves was double the power required to drive the car, so halved fuel economy...

Personally, I am more of a fan of additional power recovery via turbine driving generator (I really like Mercedes F! packaging). Getting more power out of the fuel I put in, beats putting additional fuel in.

*Sleeveless valves scrape carbon away very similar to how it is done with Wankel - similar oil control and thermal issues on exhaust port.

 

[85_Ranger4x4]

In order to start, engine needs air under compression and fuel as vapour (not liquid). Rings don't seal tight enough to maintain compression indefinitely and fuel will condense on cylinder walls/head/piston, so you can't get stopped engine to start without a little assistance. So, you still need a starter motor. But because you could hold valves open on all but one cylinder, the starter could be much smaller (motorcycle sized).

A modern gear reduction starter is already tiny.

When we first got the starter for dad's '96 F-250 we thought they gave us the wrong one. It is the same size as a lawn mower starter. But because it is a gear reduction it whips over that 460 like nobody's business.

 

[stmitch]

Until we see pneumatic valves in a production engine, doing the whole camshaft-less is probably too risky for an automotive manufacture. (Until we see a pneumatic valve consumer motorcycle, it still vapourware to me).

It's coming to a Chinese road near you very soon: http://koenigsegg.com/qoros-debuts-driveable-freevalve-qamfree-engine-at-2016-guangzhou-motor-show/

If you look at the FreeValve videos, it looks like they still use a valve spring of sorts, although it might be smaller than traditional valve springs.

 

[don4331]

85_Ranger4x4:

I gotta laugh - the starters on late 60s/early 70s, Dodge were small gear reduction motors, and were the worst pieces of junk on market. I replaced more Dodge starters then Ford and Chev combined and Dodge didn't have 10% of market locally. I hope yours lasts.

stmitch:

In same time period as the Renault pneumatic valve debuted, Lotus produced a car with active suspension. And it was said to be right around corner for production cars. Yet, since '85, we have yet to see full active suspension in cars. They are getting close but they have baby stepped their way through the technology.

Koenigsegg might move this technology through quicker but I'm not holding my breath that it will be in next generation Ranger.

 

[85_Ranger4x4]

85_Ranger4x4:

I gotta laugh - the starters on late 60s/early 70s, Dodge were small gear reduction motors, and were the worst pieces of junk on market. I replaced more Dodge starters then Ford and Chev combined and Dodge didn't have 10% of market locally. I hope yours lasts.

They are all over, the one that was on the truck was an ancient Napa one. I know John Deere has been using them for over 20 years on their big diesel tractors.

The one on my F-150 is factory original and knocking on wood works perfect after 14 years and 150k miles.

 

[adsm08]

They are all over, the one that was on the truck was an ancient Napa one. I know John Deere has been using them for over 20 years on their big diesel tractors.

The one on my F-150 is factory original and knocking on wood works perfect after 14 years and 150k miles.

Keep knocking on that wood. Those 5.4L starters are a PAIN.

Ford really screwed the pooch on that one. They should have put the bolts in from the back, like Jeep does. Instead they put them in from the front like they normally do and made them all but inaccessible.