enginehistory.org

[wallan]

First, just been checking through past issues of TM, and noticed Mr. Bompas' letter, in Volume one, Number four, and his comment about Napier being encouraged to stay in theaero-engine business. It was British policy to support four aero-engine makers, RR, Bristol, AS and Napier, in the Twenties and Thirties. This is why Richard Fairey got little support when he brought the Curtiss D-12 back from America, and Fairey weren't allowed to develop their 24 cylinder engine.

Sleeve valves have another benefit that wasn't mentioned. Due to the continual relative motion between the piston rings and sleeve valve, there is no breakdown of the oil film when the piston reaches TDC, and there is no ridge worn into the sleeve by the top piston ring. (there is a research engine that has been developed in which the cylinder liner rotates, to prevent this wear.

Finally, is there anyone out there brave enough to make a full-size Rotating Cylinder Valve (RCV) engine?

[gwhite]

I thouhgt I mentioned the lack of a wear ridge in my original article? The analogy being a surfer, as long as there is realtive movement, the rings do not pop through the oil film. As you know, Ricardo discoverd this aspect of sleeve valve engines.

[wallan]

You did mention it before, but I added it, above, in case anyone went back to Mr. Bompas' original letter, (when he was talking about the downside of sleeve-valves) and so I could mention the rotating liner engine.

[szielinski]

No offence to the guys at Texas Uni (at least we know the engine would be BIG, like everything else in Texas), but it seems the complexity of a rotating sleeve with no ports in it is a bit like having an atomic clock to boil an egg:- over-engineered and under-utilised.

(wish I was at that uni...)

[gwhite]

Another problem I see with that engine is the fact the sleeves only rotate, they do not reciprocate. Therefore, I cannot see any great advantage in this. It seems that to get the wear resistance you need both reciprocating and rotating movement. Seems to me like the guys un Texas have too much money and too much time on their hands.

[jaymerich]

Hi!: one of the questions addressed in this superb paper is the piston temperature, supposed to be higher in sleeve than in poppet valve engines. I read in the July 74 Car & Driver magazine issue, an interview with the british racing gearbox producer Mike Hewland, that during WWII worked in a "mobile labour force", with involvement in sleeve-valve engines production. In the Car & Driver report he announced he was working in the 1970's, along with his collaborator John Logan, in a single cylinder, 500 cc displacement sleeve-valve engine, aimed to improve existing Formula 1 engines, and giving 73 HP, with a torque of 47.5 lb.ft. He claimed having measured piston temperatures, that never exceeded 270º C in the center, 240º C in the edges, sleeve temperatures of 140º C, cylinder head temps of no more than 150º C and an SFC of .45 lb/HP/hr -racing version- to .39 lb/hp/hr -economy version- 170 gr/hp/hr-, the engine was run up to 10,000 rpm, with a compression ratio of 10:1 on two grades below commercially available fuel; no follow up for this work available, as far as I know

[fbarrett]

Jay:

As you probably know, piston crown temperature can be reduced, by oil squirters from below, etc. For example, Porsche began using this method in the 911 air-cooled engines in 1970. It would be interesting to know what other piston-cooling methods are effective.

Frank

[jaymerich]

Thanks for your interest: Hewland never indicated an special cooling system, it seems that simply heat had not a high tendency to accumulate in the piston, but the subject was not openly addressed in the interview, so a wide margin for doubt and guess-what exists. What I am sure of, is that he put no special oil feeding system for the sleeve, spilling from other parts of engine was enough. If you see in Youtube, search word sleeve valve, you can see some interesting images of recent work with sleeve-valve engines, although not too deeply explained, and read also some discussion on the subject. Enjoy new year, salut +

[jaymerich]

Good news for SV engines lovers!: SAE published a paper by Muhammad Hafidz Rahmat et al, entitled "Side Opening Intake Strategy Simulation and Validation for a Sleeve Valve Port Application", it has numbers
2009-32-0130/ 20097130 , and can be bought and downloaded from the SAE site, www.sae.org ,as usually. Enjoy it, give yourself a quick to enlarge the number of modern contributors to SV progress