If you look through the Wikipedia article on Toyota engines, you can sort of predict the areas where the next model’s improvements will be. For example, once they got the fuel injection and ignition system working pretty good, next they move on to variable valve timing.
I got to wondering if there’s ever been an auto-engine design that does away with the rotating camshaft completely, and opens and closes the valves with electrical solenoids instead? Magnetic forces in other words, rather than mechanical pushing.
Some company (I forget whom) built a small block Chevy engine a quarter century ago that used solenoids to operate the valves.
To me anyway, it’s a fantastic concept if any reliability issues can be overcome as there would be no drag on the crankshaft, noise would be reduced, power and fuel economy upped, and valve springs with much lower tension could be used.
What I wonder about is the effect of exhaust valve heat transfer into the solenoids.
A small engineering company also developed and successfully tested a V8 engine using shafts containing rotating ball valves in place of camshafts, rocker arms, and valves. I don’t know what became of it. To me it looked extremely promising.
There have been engines without cams before. My memory is a little fuzzy on this but I think it was Williys-Knight that made a rotary sleeve valve engine, all you would need would be a mechanism to move the sleeve up and down to make this a variable valve area engine.
It seems to me that the solenoids could be actively cooled if required. The can also be made of materials that can withstand temperatures of 250F. When I say actively cooled, I mean either engine coolant or forced air cooling.
Considering the advances in roller cam followers, roller rocker arms and low rate bee-hive valve springs as well as mechanical variable cam timing and variable lift systems, it would seem like valve solenoids might not provide a much greater advantage.
This has been investigated for a long time. See this report from 1998 about testing on a Kohler engine for DARPA by a system developed by a company called Aura
The big coils would be slow to build and reverse the magnetic force. It is tough electrically to slam the coils with current to open the valve and then suck that current back out to close the valve. It must be harder than it seems or we’d have it already.
To me anyway, it's a fantastic concept if any reliability issues can be overcome as there would be no drag on the crankshaft,
The concept is absolutely fantastic. I read about it years ago. Someone built a cam-less engine over 30 years ago. The problem was reliability. That is the biggest hurdle they had to overcome.
People put aggressive racing cams in their cars for better performance…but the idle like crap. With this setup you can actually have a vehicle that idles perfectly…gets good gas mileage…and have the performance increase of a aggressive racing cam…all controlled electronically.
Cam controlled valves is a very simple and extremely reliable setup. There really isn’t much that can go wrong (OK…timing belts do break…I’ll give you that). You can get hundreds of thousands of miles on that setup without ever touching the inside of the engine.
If the cam-less engines can get to over 200k miles without needing service…I think that would make it very desirable. But if you they only last 50k miles…that would be bad.
There are always advantages with replacing a mechanical system with an electrical one. Reliability for one... I suspect the camshaft will follow the carburator and 9 track tapes into history.
The electrical components will last a long time…but as @texases pointed…this is Electro-mechanical. The mechanical part is what is likely to fail. And as I said…this is being worked on TODAY…and Reliability is their biggest issue. Right now it’s no where near as reliable as the cam system.
Things like starter motors and alternators are not especially reliable.
Last time I replaced a starter or alternator was on my 84 GMC S-15. Every vehicle we've owned since then they've lasted as long as the rest of the vehicle...that's hundreds of thousands of miles on each vehicle. Starters and alternators are far more reliable then they use to be.
To me, the thought that every component of valve operation would be managed by computers for the level of performance required would be the most powerful reason to use electric valve actuation. Now we have very complex electro-mechanical devices to alter timing and sometimes lift. We have seen amazing increases in engine output per cubic inch or cc with computerized management of spark timing, intake flow and fuel mixture delivery and I expect electric valve actuation could deliver similar gains.
True, but more reliable than the cam/timing chain? I bet a lot more starters/alternators are replaced overall than cams and timing chains.
Cams - yes…Timing chains - NO. Over time chains will stretch and then slip. But not til 250k+ miles. Chains are in stress the entire time the engine is running…Starters…and alternators…I’ve had several that lasted well over 400k miles. I do think this is an edge case…they both last a long long time. But at least if a starter or alternator break…it won’t destroy your engine.