Talk:Camless piston engine

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Above undated message substituted from Template:Dashboard.wikiedu.org assignment by PrimeBOT (talk) 16:36, 16 January 2022 (UTC)

Desmodromic not "camless".
Desmodromic systems are not "camless", I don't know what that's doing in here. TomRawlinson 15:07, 5 May 2007 (UTC)

"Sliding friction between the surface of the cam and the cam follower which rides upon it is considerable. In addition to mechanical friction, considerable force is required to overcome the valve springs used to close the engine's valves. This can amount to an estimated 25% of an engine's total output at idle, reducing overall efficiency. A roller follower valvetrain has significantly less friction and allows for concave cam lobes. Two approaches have been tried to reclaim this 'wasted' energy of the valve spring, but have proven difficult to implement:"

I don't know where this info came from but it is very misleading. Considerable force is not required to overcome the springs. When a spring is compressed it is holding the energy used to compress it and will release that energy back to the valvetrain when it is uncompressed. This is why there is no negligible harm in using slightly heavier springs in a valvetrain than required. 25% seems very overexaggerated.LrngCrv (talk) 05:29, 11 January 2008 (UTC)

Camless engines already in production
MAN B&W Diesel are already producing engines which make use of electrohydraulic valve control rather than camshafts, rocker arms and pushrods.

http://www.mandiesel.com/files/news/filesof2810/p412-0503.pdf

The current article is so exclusively car-focused that I don't know how to slide this in. Anyone else care enough? --Joffeloff (talk) 00:10, 17 March 2008 (UTC)

Lots to do
Lots of work to do. This article as it stands is mainly WP:OR, there are many good references but they don't support most of the claims made in the content.

But it's interesting and mainly needs cleaning up. Andrewa (talk) 17:42, 6 March 2013 (UTC)

Want to know that free valve is compulsory for camless engine.
I am Engineering student and doing my project on camless engine. So I want your help to get me free valve that Koenigsegg use in its camless engine. My project has too simpler way to get timing of engine intake and exhaust valves. I hope you support new innovative ideas. Mech. Engineer Student India Deshmane Akash (talk) 16:24, 27 July 2017 (UTC)

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"Free valve"?
Maybe I'm mixing something up here, but I thought a "free valve" engine was an old-fashioned sort of camless engine, where the valves are held in place by very weak springs, and operated by the airflow itself. The springs are very light duty, so when the piston starts its intake stroke the suction/air pressure lifts the valve off the seat, allowing the air to flow in; when the piston starts the compression stroke, it forces the valve shut and the pressure of the compressed mixture, and then the combustion, keeps the valve tight on the seat. I think this only works for the intake valves, meaning the exhaust still needs a cam to operate. I think they used this system on WWI-era rotary aircraft engines (not to be confused with Wankel rotaries). The downside to this system, is that it only operates in relatively slow engines, since the valve cannot be operated fast enough without a strong spring or other system to operate it, and you loose some of the mixture back into the intake before the valve can close, effectively reducing the working displacement of the engine (sort of like an Atkinson cycle, I guess). Anyway, that's what I thought a "free valve" engine was. A free valve engine may be a form of camless engine, but not all camless engines are free valve. If the valve is actuated by some power source, it's not actually a free valve; it's just a camless valve. These engines literally have valves that are not actuated by anything, and which just slide freely back and forth with the intake flow of the engine. That's "free valve".

Idumea47b (talk) 04:11, 27 May 2020 (UTC)

：Freevalve is a trade name used by the eponymous company, a sister of Koenigsegg. As far as I know, their use of the word "freevalve" is unrelated to the systems you describe. — Preceding unsigned comment added by I5-X600K (talk • contribs) 03:13, 18 December 2020 (UTC)