Camless V8 Engine

[Ed S.]

This is not "Corvette" related but an interesting development none the less. If I it is the opinion of others that this post is inappropriate for this forum I will respectfully delete it.

Apparently Koenigsegg of Sweden has developed an technological approach to a traditional valve-in-head internal combustion engine that has no camshaft. Valves are operated by pneumatic / solenoid type devices (I'll call them lifters) that are computer controlled. The article claims the valve timing is infinitely variable and provides other advantages - no friction from the cam gear being one. But I wonder if the devices that open and close the valves can operate as fast as a cam pushing on a lifter can operate them. Consider an engine running at 5000 rpm, the cam is rotating at 2500 rpm. Any given lobe raises and lower its assigned valve 2500 times per minute or roughly 41 times a second. Can a solenoid actuated pneumatically operated "switch" operate that fast? Don't know. The other issue is how fast or slow does it open or close - wonder if that action can be "controlled", same with how much a valve opens or closes. I guess one benefit is that a "tuner" should probably be able to modify the computer program that operates the lifters so a car will sound like it has a 30-30 cam in it.

http://www.foxnews.com/leisure/2016/01/07/inner-workings-koenigseggs-camless-engine-revealed/?intcmp=hpff

[Thad L.]

Re: Camless V8 Engine

Sounds like old F1 technology 👍🏻

[Douglas L.]

Re: Camless V8 Engine

People have been trying to put camless engines in production for awhile now. Along with the ability to have the perfect cam timing/lift for every possible operation conditions, combined with COP ignition and DI fuel injection, has the potential to start the engine without a starter motor. Ideally the system would be purely electrical but as I understand it power consumption is really a problem going that route so I would imagine thats the reason they used to electric/pneumatic (similar to a modern diesel fuel injector)route.

[Duke W.]

Re: Camless V8 Engine

As stated, the idea of eliminating mechanical valve trains has been around for a long time - decades, in fact - solenoid actuated, computer controlled valves that would allow infinitely variable timing and lift, and, in fact, eliminate the throttle valves on spark ignition engines - what's called "intake valve throttling". Many prototypes have been built over the years, but apparently none have achieved a combination of function, low power consumption, cost, and reliability to make them viable for high volume production, high speed automotive engines.

These systems take a lot of power to operate - likely more than a mechanical valve train, which has less friction that you may think because most of the spring energy stored at full lift is returned to drive the cam on closing except on very high speed valve trains. Most of these systems have a light spring to keep the valve normally seated, and then the solenoid overcomes the spring to both open and close the valve, so power is required for both directions because the spring doesn't have enough energy to close the valve rapidly.

This pneumatic system would require high pressure pumps and high frequency switching valves, so it likely has no shortage of complexity and cost, and as the article states, there are issues to overcome before it could be considered "production ready". Don't hold your breathe. Also, it takes a lot of power to compress air, so I question the claim that their pneumatic system would require less power to operate than a conventional, simple mechanical valve train, which are actually pretty efficient for the reasons I described above. Remember sleeve valves?

When spring cycling frequency gets to a very high value the springs get very hot (known as "hysteresis") and have to be cooled, which is a loss of energy. This is where the "pneumatic" part of F1 valve trains comes in. It's conventional other than using pneumatic (air) valve springs rather than conventional mechanical valve springs.

Something similar happened with 42 volt electrical systems, which were all the rage and "right around the corner" ten years ago. Actually, I think they were 14/42V systems, which retained a conventional 12V battery for the starter and low load systems, but high load systems such as electrically driven a/c compressors and electric power steering would run on 42v. Alternators would have both 14 and 42V output.

For a given power requirement, tripling the voltage reduces current by two thirds, so smaller wire gauges could be used to reduce cost and weight. Modern cars probably have something on the order of at least 50 pounds of wiring. The whole idea died, suddenly. Apparently the industry could not come up with a set of common standards, and one of the issues was protecting operators, passengers, and mechanics from electrical shock.

As I said and gave examples in one of the opening charts of my 2012 San Diego National Convention, not much of the basic guts of the automotive engine has changed in well over 100 years, and I don't expect that to change anytime soon. Also, many have been predicting the demise of the IC engine for decades, but it just keeps trucking along with continuous incremental improvements in the basic technology, especially the control system, and I won't bet that will change anytime soon, either.

Duke

[John H.]

Re: Camless V8 Engine

Valves are operated by pneumatic / solenoid type devices (I'll call them lifters) that are computer controlled. The article claims the valve timing is infinitely variable and provides other advantages - no friction from the cam gear being one. But I wonder if the devices that open and close the valves can operate as fast as a cam pushing on a lifter can operate them. Consider an engine running at 5000 rpm, the cam is rotating at 2500 rpm. Any given lobe raises and lower its assigned valve 2500 times per minute or roughly 41 times a second. Can a solenoid actuated pneumatically operated "switch" operate that fast? Don't know. The other issue is how fast or slow does it open or close - wonder if that action can be "controlled", same with how much a valve opens or closes. I guess one benefit is that a "tuner" should probably be able to modify the computer program that operates the lifters so a car will sound like it has a 30-30 cam in it.

Formula 1 engines have used this technology for almost 20 years, using a closed-loop 2500-psi air system operating air actuators to open and close the valves with electronic controls; their engines routinely ran up to 20,000 rpm with the air system as the enabler until the recent turbo V-6 formula reduced maximum rpm to 16,000. This is a horrendously expensive solution to avoidance of valve float, but it's peanuts to a typical Formula 1 engine design budget.

[Douglas L.]

Re: Camless V8 Engine

I was under the impression that Formula 1 engine simply used a pneumatic spring in place of a coil spring to close the valve and the opening was still done by a conventional cam, is this incorrect?

[John H.]

Re: Camless V8 Engine

I was under the impression that Formula 1 engine simply used a pneumatic spring in place of a coil spring to close the valve and the opening was still done by a conventional cam, is this incorrect?

Doug -

That's correct - a direct-acting cam lobe opens the valve, and a high-pressure air-operated actuator closes it. Ducati pioneered the Desmodromic valvetrain decades ago that both opened and closed the valve via cams and followers on production motorcycles (and Mercedes-Benz used it on some race cars), but hysteresis and harmonics plagued the mechanical system over 10,000 rpm.