Tech.-Question for experts: Diesel engines in US fleet boats..

[Catfish]

Hello,
i am no expert, however i came about an info there were a lot of two-stroke Diesels built and used for ship engines, and Diesel submarines.

As far as i know the Gato and Balao class had four of those, where some of them would either charge the batteries, or drive the boat.

Now those engines had roots blowers, and

(i am not sure about the following - just asking)

a special injection technique, where the injection pump and the injection jet were combined to one system, called "injector". So there was one injector for every cylinder. Maybe one could call such an injector a pump-jet or whatever.

Does anyone know when this system was invented, and whether there is a patent/license for this kind of injector system ?

Thanks and greetings,
Catfish

[Fish40]

You may find your answer here: http://www.maritime.org/fleetsub/diesel/index.htm

[AVGWarhawk]

I believe the injectors were worked much like todays diesels and that was off a camshaft. Look for Fair Banks diesels. I'm also thinking the Germans were first in the engineering of injection. Specifically in the Bf109. Not sure on that but a good place to start.

[Catfish]

Hello,
AVG Warhawk, thanks a lot ! I think i found it in the Fleet boat manual.

@Fish40 thanks but i only meant Diesel injection systems - but then there was a Junkers Diesel plane engine - ok, will look for info on this, too.

Seems the Detroit engines used such a kind of injection system. Astonishing, since the Volkswagen company claimed the invention of this a bit later lol

Thanks and greetings,
Catfish

[Lt Cmdr. Duke E. Gifford]

All diesel engines are fuel injected, that's the only way a diesel works. There is no throttle on a diesel, RPM and power output are controlled by the fuel injection system. A diesel does not even generate vacuum like a gasoline, LPG, CNG, or alcohol fueled engine, because there is nothing to control the amount of air entering the engine. For a diesel, fuel injection not only replaces the carburetor on a gasoline engine, but also the ignition system, because it is the injection of fuel directly into the cylinder full of hot compressed air that causes combustion to occur.

The two stroke diesel with a "roots" type positive dispalcement crank driven supercharger is most typified by the older (pre series 60) Detroit Diesel engines. Two stroke diesels, much like two stroke gasoline engines, run at a higher RPM than their four stroke counterparts, and make less low speed torque. Once very common, especially in fleet type trucks, as well as some marine applications, the two stroke has fallen out of favor, as it is dirtier as a general rule than a four stroke, and again, it makes less low speed torque, requiring a higher RPM range.

The supercharged diesel, be it crank driven positive displacement supercharging or exhaust powered turbo supercharging, doesn't require a different TYPE of injector. However, it does require either a larger injector or a higher volume injector pump, or both, to supply the additional diesel fuel required by supercharging. The higher the fuel pressure, at least to a certain extent, the better the burn in a diesel, creating more power for a given volume of fuel. Modern diesels have much higher fuel pressure than their predecessors.

[DaveyJ576]

It is important to understand that the Fleet Boats (with the exception of a few Salmon/Sargo boats) all used a "Diesel-Electric" arrangement for propulsion. That is, none of the engines were connected to the propeller shafts. The engine's only purpose in life was generating electricity. The electricity produced was then used as needed for ship's systems, charging the battery, or propulsion through the motors that were connected to the shafts. The big diesels simply drove generators and nothing else. This was a tremendous advantage mechanically and operationally.

It allowed the engines to be run at a fairly constant, fuel efficient speed and reduced stress on the engines from constant speed changes. It eliminated clutches from the drive train, providing a rapid and trouble free method of backing down, a real advantage while maneuvering in harbor. The engines could also be located more efficiently within the boat, eliminating the necessity of aligning their crankshaft directly with the propeller shafts.

As mentioned before, all but the last four of the Salmon/Sargo boats had what was called "Composite Drive", a complicated and cramped combination of Diesel-Direct and Diesel-Electric. While generally successful, the arrangement of the aft two diesels inboard of the shaft but aft of the reduction gears made the engine room very cramped and made working on these engines difficult. This un-needed complication was done away with on the Seadragon, Sealion, Searaven, and Seawolf and these four boats reverted to the standard Diesel-Electric drive, as did all subsequent Fleet Boats.

Dave

http://pigboats.com

[Catfish]

Hello,
first thanks for the history !

Driving an older small Diesel (1984) myself, i know you need a fuel injection for those engines. I have converted mine to also run with pure rape seed oil, with pre-warming, other glow plugs, advanced injection timing and other injectors (and higher injection pressure) it even runs better with this oil than with Diesel. Next thing will be an intercooler for the exhaust-driven charger ;).

Now what interested me is who invented the not-central Diesel fuel injection, not via one central pump (rotary or piston-driven), but the system where every cylinder has its own "pump-jet" - and it seems it was definitely NOT Volkswagen, but Detroit in the 1930ies.
VW claims to have invented the pump-jet system, and is currently giving it up for the (cheaper) common rail Diesel system and even higher injection pressure of up to 2000 bar (my old 1984 one has some 185 injection pressure). However it seems they were indeed not the first ...


So the later U.S. fleet boats used a completely diesel-electric system, and did not have a direct-driven propshaft, but electric motors powered with electricity, provided by the Diesels. Seems they were indeed different from the german subs with "composite drive" during WW2, only the latest german types (IX DII, and certainly XXI) were directly constructed to use diesel-electric propulsion.

Thanks Mr. Gifford and Dave :up: and for the pigboat link,
Catfish

[Mr.O'Bannon]

What is the cost of pure rape seed oil per gallon/litre?

[SteamWake]

and here I thought rapeseed was a typo :lol:

http://www.cogeneration.net/rapeseed_biodiesel.htm

[Sailor Steve]

:rotfl:

I was wondering about that myself, but didn't think to look.

Lt Cmdr. Duke E. Gifford and DaveyJ576, thanks for your explanations, and to you and Mr.O'Bannon, WELCOME ABOARD!:sunny:

[Catfish]

Hello,
well as non-native speaker i wondered how i should have to translate this :oops:
:lol:
But it's not even "Biodiesel", but pure plant oil made from rape seed - no conditioners, or anything. "Biodiesel" is esthered, and a bit agressive towards normal rubber and some plastics; while pure oil is inert. Only poblem is it is thicker/has a higher viscosity than Diesel fuel, so you have to warm it to appx. 75 degrees Celsius. Until normal temperature of the engine is reached, you warm it with an electric heater, until the radiator's cooling liquid is hot enough to pre-warm it via a heat exchanger. It currently costs 90 Eurocent per litre, and Diesel is only bit more expensive - now. ;)

Anyway thanks a lot for the explanation, and greetings,
Catfish

[Urge]

So, what model 1984 VW do you drive? I'm driving a 1982 diesel Rabbit pickup 40-50 MPGs. I love it. If I could afford it I would convert to used veggie oil, its free and your vehicle goes down the road smelling like french fries.

Urge

[Catfish]

Hello,
it is a 1984 Quantum station wagon, Turbodiesel, 1.6 litre, 73 hp, but no Synchro. Engine is a CY type.
It is not necessary to change anything if you use half Diesel and half Veggie oil.
If you build a two-tank solution (Diesel for starting and 100 percent Veggie for driving), you do not need to change anything either. Just start the engine with Diesel and switch to Veggie oil when it's warm, and remember to switch back to Diesel before you stop the engine for better starting. This is quite simple, a small tank with Diesel, and the built-in for Veggie oil. Switching is via a cheap electro-magnetical valve.

For 100 percent vegetable oil in a one-tank car you better change some things:

- Fuel lines tank-engine with a larger diametre (against the thick, viscous oil)
- A switchable, or temperature controlled electrical heater, best to insert before the Diesel filter, for cold starts
- A heat exchanger heated by radiator cooling liqid for driving when engine is warm.
- Other spark plugs (longer, more sturdy, e.g. Bosch Duratherm Chromium 23mm)
- Another pre glow relais, for longer glowing after engine start
- Other fuel injectors (so-called pre-spray ones, set to a higher opening pressure at 175 bar)
- You have to advance the injector timing a bit (rotate the injection pump), but not too much !! 0,97mm to 1.1mm should be enough with the Turbodiesel engine - the latter is too much for pure Diesel - do not run the engine at full speed with pure Diesel and this setting (the upcoming piston will get the explosion before it's at the upper dead end, thus causing damage to the big end bearings sooner or later).

Disadvantages of one-tank system:
- You have to hold engine revolutions well below 2500 rpm in the first 3 minutes after starting, the car will not be very responsive directly after starting.
- If the injection pump begins to leak, you will have to change one or two seals. If you renew it with Viton rings it should also be able to run with aggressive Biodiesel without problem - if you ever use it ...
(Diesel and Biodiesel have some conditioners which make rubber swell, so the missing Diesel will probably make some rubber sealings shrink - the pump may leak)
- Tanking pure Diesel the car will suffer a definite lack of performance, do not run it at full revs until re-adjusting the injector pump for pure Diesel again.
- Because of the possible polymerisation of Veggie oil with motor oil the oil-change intervals should be shorter - say every 3000 miles to be at the safe side.

Advantages:
The car will perform a bit better/more responsive with rape seed oil
You will get better mpg, if only a bit
You do not blow absorbed CO2 into the atmosphere
It was cheaper than Diesel a year ago, but now ...
You will only have to buy grease and motor oil from the oil industy ;)

Greetings,
Catfish

[Aramike]

and here I thought rapeseed was a typo :lol:

http://www.cogeneration.net/rapeseed_biodiesel.htm
LOL! Me too...:lol: