Paul
Reading through Garrett's material and other sources on the NET I came
across an old project they were doing called "hydraturbine" or hydraulically
assisted turbocharger (HTA)in the late 90s.
The technology was developed by Kapich Engineering, and "improves boost
response, especially at lower rpms. It also allows the turbocharger to be
designed with less backpressure, thus improving efficiency across the
operating range. The amount of hydraulic assist can be varied to suit the
application; a separate controller and special lubrication system are also
needed."
You probably know it was concept of incorporating a small efficient "25 cent
piece diameter size hydraulic turbine" into the back side of a centrifugal
air compressor.
The HVA concept was and is being used now in large diesel applications that
have two sequential turbos chargers. The HTA system replaces one of the
turbo chargers and eliminates turbo lag. Now we are seeing the big diesels
moving on to the next step of electric motor assisted turbos. We have
already throughly covered the disadvantageous of electrical motor driven
compressors..
The HVA compressor however can be downsized and located as part of the
Intercooler and also take advantage of some rammed air and wouldn't have the
heat soak problems of residing next to a hot turbo. Of course the hydraulic
motor would have to derive its energy ultimately from the power shaft via a
hydraulic oil pump. Francious' engine could run it off one of their PTOs on
the front housing. The pump would be a smaller than a normal sized power
steering pump and as mentioned above have its own close loop oil supply.
..but......
Looking at the HVA technology as part of a turbo compound system: What are
your thoughts on using it for providing the engine boost and then using a
turbo and the planetary gearbox for recovering energy for the compound? This
lightens things up considerably and allows us to hone in on all the
components designed point of use. As an added project moral 'boost' (sorry)
the turbo/gear box could bolt up easily and be moved to an more convenient
engine location to allow connection to the drive belt.
I think plumbing weight savings justify some of the hydraulic driven losses
because the HVA drive mechanism is not as efficient as a turbo driven
compressor. However looking at it from the total system point of view, the
gains and advantages are definitely there. Supposedly the HVA technique
would be much more efficient than a belt driven Roots supercharger and a
heck of a lot easier and lighter to control boost. Perhaps a miniature servo
motor driving a needle valve interfaced to the manifold pressure sensor with
manual override functions would work on the prototype.
I haven't looked into sizing hydraulic pumps lately but I would venture to
say it could be small and compact. Another crazier and lighter idea is to
to use freon to drive the micro turbine and a small air cooled heat
exchanger condenser to let the liquid drain back to the flash
heater/compressor on the exhaust. Similar freon flows are used on camper
propane refrigerators albeit with a different goal.
Cheers
Doug in Japan
PS Thanks for the replies on suggested A&P mechanics. Placerville is
probably the safest and nearest at this time.
Yes I have a SAE paper on that hydraulic turbine assisted
turbo charger. The whole idea is to allow the diesel engine
to accelerate faster without generating a lot of black smoke.
Soon to be an essential feature here in California.
I don't see any applications for turbo compound but that is just
me.
Paul Lamar
Paul
I wonder if I am missing something. Perhaps I misunderstood the articles I
read. Was the hydraulic connection simply an addition to the already
assembled turbo/compressor unit? A system to eliminate turbo lag only?
Somehow I got the impression from some articles that the oil driven
compressor was driven 100% by oil via a hydraulic motor. Sort of like a
hydraulically driven supercharger.
Hmmm.
doug in Japan
Yes on your question.
The paper I have is IMechE C41/82 1982 "Power transfer to improve
transient response of a turbocharged diesel engine."
Some engineers at Garrett California wrote the paper.
Hydraulic HP is used to accelerate the the turbo charger
and provide additional combustion air to allow the diesel to accelerate
faster. Diesels have no air throttles. All engine acceleration is
accomplished by enriching the mixture. There is a limit to how
fast you can enrich the mixture. If done too fast black
smoke comes out of the exhaust. This is referred to as the
smoke limit. If you have ever seen a tractor pull contest on television
or in person you will appreciate this fact. The entire stadium is darkened
by a huge cloud of dense black smoke. Thousands of people are
exposed to a huge douse of carcinogens in one fell swoop :)
I digress.
The draw back of course is this HP comes out of the engine
and a bit more overall fuel is burned to generate it.
Same goes for the electric assisted turbo charger.
Paul Lamar
BTW we are dropping all people on AOL in one week. We are still
getting too many bounces.
Paul Lamar
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