VVT & rewriting history - Page 2 - Alfa Romeo Bulletin Board & Forums
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post #16 of 23 (permalink) Old 09-07-2006, 09:16 AM
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Originally Posted by alfavirusnz
I remember reading in the `70s or thereabouts (when the cars were current )that Alfa was experimenting with VVT in the `70`s when the Alfetta Berlinas came out and that there were Alfetta Taxi`s in Milan that were used as a quiet proving ground for some of this technology.

Richard J
Well, that was another experiment, and I don't remember it included VVT. The Milan taxis you refer to were fitted with a "modular" engine controlled by Alfa's own electronic management system called "CEM" (controllo elettronico motore). Actually, at idle and low revs, low charge, only two cylinders were active. To avoid heat distorsion, at each switch of the system, a different couple of cylinders was turned off. This worked pretty well, a bit rough on the transistion between 2 and 4 cyl. cycles, but at an acceptable level. Even a GTV6 with an atmo bank and a a turbocharged one was developped in 1984 on the same principle of modularity, the 3 atmo cyl. running all the time, and the turbo one switching on when power was needed.

Tubolarespider: a 6C2500 with "Ala spessa" body ran the 1940 Mille Miglia with the fuel injection system. It's described in Angelo Tito Anselmi's book "6C2500". Remember that the Daimler Benz 601 engine on the Messerschmitt fighters (and the license-built Alfa Romeo RA1000 RC41) featured direct injection during WWII.

Ferrari had also developped a variable timing-variable lift system in the 70s, for racing use, where the cams had a conic shape, so that the whole camshaft was moved fore and aft, and the cam followers thus were driven by a different profile. Too fragile and too complicated. BMW doesn't move the camshaft, AFAIK, with its valvetronic system. It acts on the cam follower instead. Fiat is developping the "famous" Uniair system that will dispense with the air manifold butterfly (as does the BMW system), but it has another principle: it's an hydraulic system between the cam follower and the valve. Let's see when it will be introduced. Basically all those systems, including the Alfa CEM tried to address the losses by "pumping" vacuum at low charge

Spica was lso an Alfa subsidiary, and I would be interested in the documentation you quote
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post #17 of 23 (permalink) Old 09-07-2006, 09:25 AM
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The SAE paper for the CEM is 850290, I had to order from our library, since it was not part of the normal annual archive from SAE. Good stuff. Thankfully, my employer is good at getting technical documents...

Here's some extra stuff Don sent me:

Quote:
AlfaRomeo was granted patents in 1975 for a method of changing valve timing to suit load conditions. This system was presented to EPA for 1980 certification in 1978, at which time this writer coined the acronym “VVT”. The 1980 M.Y. AlfaRomeo 4-cylinder engine family was the first ever production application of VVT. Today, we see other VMs touting “VVT: (or their market-speak equivalent) as “new”, “innovative”, “Leading edge technology”. Now we are in 2003, so how “new” is VVT? Further, some of this market speak is mis-“leading”, as in the buzz phrase “leading edge technology”. How can this be, when only airfoils have a leading edge? Are they using aero speak for a vehicle that never leaves the ground? Next they will be using Reynolds numbers to describe the efficiency of their HVAC outlet grilles? AlfaRomeos VVT was a concept of Ing. G. P. Garcea, my long time mentor and chief of AlfaRomeo’s think tank. The concept was developed in the experimental engine department, DIPRE ESMO. Now there is an acronym for you – which I will not explain – subject for another article. Of interest is that Ing. Garcea was an aeronautical engineer who paid his dues in Via Avio at Portello. Interestingly, he never used the word “leading edge”.
I'll see if I can remember to get some more of this from home- including the document about the early EFI.

I know the DB development on DI, which was basically a derivative of a diesel system. Which was also what they used on the 300SLR.

Interestingly enough, knowing what I know about direct injection, the SPICA was more than capable of doing DI, if they wanted to. I wonder if they ever tried....

Eric
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post #18 of 23 (permalink) Old 09-07-2006, 10:01 AM
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Quote:
Originally Posted by turbolarespider
The SAE paper for the CEM is 850290, I had to order from our library, since it was not part of the normal annual archive from SAE. Good stuff. Thankfully, my employer is good at getting technical documents...

Here's some extra stuff Don sent me:



I'll see if I can remember to get some more of this from home- including the document about the early EFI.

I know the DB development on DI, which was basically a derivative of a diesel system. Which was also what they used on the 300SLR.

Interestingly enough, knowing what I know about direct injection, the SPICA was more than capable of doing DI, if they wanted to. I wonder if they ever tried....

Eric
Spica was bought by Alfa (actually IRI, the state holding) in 1940 since, with diesel trucks and aero engines being 95% of Alfa's activity, the construction of fuel pumps was strategic. So Spica indeed also built under license the pumps and injectors for DI. But the 6C2500 had instead an indirect injection.
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post #19 of 23 (permalink) Old 09-07-2006, 05:58 PM
 
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Quote:
Originally Posted by gtv2000
Spica was bought by Alfa (actually IRI, the state holding) in 1940 since, with diesel trucks and aero engines being 95% of Alfa's activity, the construction of fuel pumps was strategic. So Spica indeed also built under license the pumps and injectors for DI. But the 6C2500 had instead an indirect injection.

I've always wondered why the 6c2500s went back to carbs rather than develop the F.I., and even the 6c2500 book doesn't make the reason totally clear
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post #20 of 23 (permalink) Old 09-08-2006, 05:40 AM
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The US patent mentioned appears to be 4,231,330 (November 4, 1980) which is derived from Italian patent 21650 A/78 (Mar 24, 1978).

Abstract:

"This invention relates to a timing variator for the timing system of a reciprocating internal combustion engine of the type having a camshaft for the intake valves and another camshaft for the exhaust valves. At least one of said camshafts is coupled to a driving gear through an annular piston housed in a cavity connected to the outside through a slide valve. The latter includes a valve element provided with an eccentric mass, which is able to overcome the force of a preloaded spring and to move the valve element from open to closed position when the rotational speed of the engine is higher than a predetermined value."

All patents cited by this one refer to variable ignition or fuel injection (but not valve) timing. No reference to General Motors is made (although they could have invented but not patented their ideas).

Go to:
http://patft.uspto.gov/netahtml/PTO/search-bool.html
and type in the patent number.

Last edited by MALDI; 09-08-2006 at 05:47 AM.
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post #21 of 23 (permalink) Old 09-19-2006, 05:06 PM
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Some Knight sleeve valve engines used a system of gears to alter the duration of the exposed ports in relation to crankshaft speed. Some time in the 1920s!
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post #22 of 23 (permalink) Old 09-20-2006, 02:02 PM
 
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and even before that, cars used a system without valves in which the cylinder , anving an intake and exhaust port, rotated. The problem was the more gass applied, the faster the rotation, and the shorter time the ports were actually open.
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post #23 of 23 (permalink) Old 09-20-2006, 07:53 PM
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Quote:
Originally Posted by dretceterini
and even before that, cars used a system without valves in which the cylinder , anving an intake and exhaust port, rotated. The problem was the more gass applied, the faster the rotation, and the shorter time the ports were actually open.
That sounds like a linear relation, no?
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