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Camless Internal Combustion and the Digital Age (hackaday.com)
szczys writes: The internal combustion engine is amazing, and it continues to evolve. Carburetors gave way to fuel injection, and a computer now monitors all kinds of sensors to ensure these engines operate at peak efficiency. But there is one thing that has remained largely unchanged: the cam shaft. This is a device responsible for mechanically timing the operation of the cylinders. It's possible to build an engine that uses digitally controlled actuators instead of a camshaft to decide when each cylinder should fire. These exist as prototypes — we have the technology, so why aren't we building with it? The answer is that change is hard, and as with the carburetor it could take an outside force (in that case mandatory efficiency benchmarks) to get automobile manufacturers to wager a bet on new technology.
The fundamental parts of the engine are all mechanical. They work without a battery.
Resilience to electrical failure is important.
Camshaft hooked up to my Raspberry Pi. Ruby on Rails controlled Iot webserver platform with home automation built in. Insteon X10 platform protocols provide robust social media sharing.
rumor is the hydraulics used a ton of power. The thing was much less efficient than a traditional cam driven engine. Sure, the valve timing and lift was perfect, but it was otherwise a nightmare.
Ever break a timing belt on an interference engine? Very bad.
One of our competitors trademarked the term "hypothesis". From now on, we will call them "boneheaded ideas".
It's possible to build an engine that uses digitally controlled actuators instead of a camshaft to decide when each cylinder should fire.
Camshafts don't control when cylinders should fire, that's an already replaced component called the distributor. Camshafts control the timing of inlet and outlet valves, and there are already formula one and other engines using electronically actuated pneumatic valve lifters.
The problem is that cam shafts are very reliable, and a single fault in valve timing, in an interference engine especially, results in catastrophic engine damage, so the software and hardware has a very high bar to meet for it to replace mechanical cams.
Also firstpost.
-puddingpimp
One of the big limiting issues in this field (BTDT) is energy consumption by the actuators and associated circuit components. Valve are heavy relative to the accelerations needed by the motion profiles. This results in ferocious energy use and dissipation.
If this power consumption is more than the engine power/efficiency gains from tinkering with profiles, the answer is an easy No.
My only relevant direct experience was for an R&D engine to test different cam profiles without having to grind sets of camshafts. It used plant electrical power, can't remember exactly how much but the equivalent horsepower was in the teens.
Bent, folded, spindled, and mutilated.
Seriously. If the technology is mature (regularly survives a 500 mile race) while providing tangible benefits (more horsepower meaning a faster car with better fuel economy which means fewer pit stops) customers will demand it.
Otherwise, it's of no perceived value to customers and might be seen as just another piece of electronic junk that is being foisted upon them (like anti-lock brakes for those of us who remember people who couldn't see their value).
Mimetics Inc. Twitter
Here is an example of a cam-less engine that has been in development for over 10 years.
http://www.dukeengines.com/
46137
No, wait... We're already talking about cars... Hmm, where does one go to for an analogy when the subject is already cars?
Don't be a wankel. Nobody likes a wankel.;)
Not likely. Why? Most likely scenario is that the valve is opened via electronics and closed via a spring. Failure == closed valve. No permanent damage.
The real "Libtards" are the Libertarians!
Lucas was working on this 36 years ago.
The real "Libtards" are the Libertarians!
http://www.motorauthority.com/news/1101737_video-shows-inner-workings-of-koenigseggs-camless
They call it a "Digital Cam" because when you graph valve lift vs time it literally looks like a square wave. The ramps really are that steep!
This compares to a conventional cam with a sudo-sinusoidal shaped wave lift profile (neglecting the effects of high RPM valve float).
Criticize as much as you want, but a truly functional electronically controlled camless engine would be the holy grail of internal combustion engine design. You can easily pick up 20 horsepower on many engines just by swapping to a performance cam, but you often compromise efficiency. But with a camless engine, in theory, you could have cylinder deactivation, low compression starts, the elimination of throttle plates (lower pumping losses), "full race-cam" profiles for performance, a cam profile for smooth idling, low emissions, etc....
Truly the best of both worlds!! That being said, there are disadvantages....
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I read an interesting SAE paper 20+ years ago describing a working prototype camless engine. The performance gains were impressive, but as I recall, there were two main obstacles:
1) Noise, Vibration, and Harshness. (NVH)
2) The valves landed harshly leading to valve seat wear. The SAE paper suggested using a method for softer valve landings.
The OP was talking about engines that can advance or retard a single pattern cam. And when you have just one cam profile, you can only change the relative timing. The duration and lift stay fixed. Duration is the number of degrees of camshaft rotation that the valve is open. Adjusting when a camshaft opens the valve doesn't change how long it stays open, or how far it opens for that matter. Electrically controlled valves can vary all 3 of those things.
Sure, the VVT tech changes from one camshaft profile to a second one. But that's all they can choose from. You either use one or the other. You might be able to squeeze 3 profiles in there if you use a DOHC setup that splits the intake and exhaust lobes between two physical camshafts and gives you room to fit the multiple patterns. But it would be a lot more complicated to do that. And you're still limited to a few fixed profiles. Electrically controlled valves do not have this limitation.
Electrically controlled valves, in theory, have "infinite" adjustability (within certain limits). You can have dozens, hundreds, probably even thousands of profiles to choose from. All you have to do is have the computer pick the profile based on load, throttle position, etc. and it changes instantly.
I just love how it looks like a Honda B18 shoespooned into a Saab wagon.
And for all the talk of a square cam profile, their system is still not square (nor will it every be.) It takes time to open and close a valve. Their system may be fast, but it isn't perfect. And I seriously doubt it can run diesel or gas in the same engine -- the compression it takes to get diesel to burn causes gas to detonate. The engine has to be designed to burn diesel, and electronically programmed to allow gas (leave the valves open to effectively reduce the stroke) -- and they'll be instantly sued by toyota/lexus because that's how their atkins cycle engines works. Any such design will be less efficient than one specifically designed for gas.
(We've had engines that can "burn anything" for a long, long time... gas turbine. Toyota built one decades ago; it was loud and sluggish, so they scrapped it. GM did the same thing back in the 70's; recalled and destroyed every one of them. Their fuel efficiency is scary -- over 100mpg. Today, they're only found in main battle tanks.)
One more MAJOR advantage of a camless design (if not the single greatest advantage) would be the ability to have extremely canted valve angles. Retrofitting an existing cylinder head design with camless engine technology is only scratching the surface. The biggest benefits would be gained by designing the cylinder head ports around the capabilities of the valve actuators. With cylinder head differences like this, we're literally talking about the difference between NASCAR horsepower levels and streetcar horsepower because cylinder head designs are the undisputed most important factor in making horsepower.
With traditional cylinder heads (on OHV engines), valve angles are limited by the rocker arms. Rocker arm rotation about one axis is trivial, but when the valve is canted it makes the valvetrain design exponentially more complex and prone to wear due to lateral loads as the angle is increased. A camless engine design wouldn't have this limitation. That being said, the camless designs have their own challenges, namely soft valve seat landings due to a nearly perfect square-wave lift profile.
I designed some spacecraft. We were limited on what we could use for a microprocessor because we needed something with history. We almost used an 8051 variant. Same goes for engines, lets say you invent an awesome engine, it even makes you toast in the morning amongst other great things like saving you fuel. You take it to one of the manufacturers, and they love it, because it saves their customers fuel and it give them more incentive to buy their products. Then they tell you, we have these things called warranty's that we offer on all of our vehicles can you tell us the MBTF? Most of the parts are new so you go back to your lab and run it for 5-10 years.
Hope this doesn't count as a Godwin, but the germans were using fuel injection in their WWII fighters, and it proved a significant advantage over carburetted allied fighters - the FW-190 could perform a radical nose-dive which would leave a Spitfire fuel-starved.
Fuel injection has been around a LONG time - just like disc brakes - but they both took a long time to make it to mass-production motor cars.
They sentenced me to twenty years of boredom