Electric motor assisted super- or turbocharger?

[Max Kallio]

2-stroke diesels need compressed air for starting the engine, so the
turbo (exhaust driven centrifugal supercharger) is out of a guestion
and it produces very little boost at low rpm anyhow.

How about supplementing a centrifugal turbocharger with a high speed
electric motor to create boost needed for starting and to enhance
boost at low rpm?

This would pretty much eliminate the turbo lag and actually help suck
the exhaust out of the cylinder at low rpm.

When the rpm rises, the electric motor could disengage or perhaps even
work as an auxilary generator.

Also, if the turbo has some problems, the electric motor could be used
at full power to help the turbo to spin and create boost at least for
the time it takes to land safely. Of course, the engine should be
able to have enough power to stay airborne at least at low altitudes
(if the load is not exeeded) even when the turbo fails completely.

Links...

www.turbodyne.com

[Don Stauffer]

Why not just have a small compressed air pump driven by gears from
crankshaft or camshaft, with a tank to store a few "starts" full of
compressed air? Seems like an easier fix than an electric driven
compressor.

Max Kallio wrote:
> 2-stroke diesels need compressed air for starting the engine, so the
> turbo (exhaust driven centrifugal supercharger) is out of a guestion
> and it produces very little boost at low rpm anyhow.
>
> How about supplementing a centrifugal turbocharger with a high speed
> electric motor to create boost needed for starting and to enhance
> boost at low rpm?
>
> This would pretty much eliminate the turbo lag and actually help suck
> the exhaust out of the cylinder at low rpm.
>
> When the rpm rises, the electric motor could disengage or perhaps even
> work as an auxilary generator.
>
> Also, if the turbo has some problems, the electric motor could be used
> at full power to help the turbo to spin and create boost at least for
> the time it takes to land safely. Of course, the engine should be
> able to have enough power to stay airborne at least at low altitudes
> (if the load is not exeeded) even when the turbo fails completely.
>
> Links...
>
> www.turbodyne.com

"Max Kallio" > wrote in message
om...
> 2-stroke diesels need compressed air for starting the engine, so the
> turbo (exhaust driven centrifugal supercharger) is out of a guestion
> and it produces very little boost at low rpm anyhow.

Unfortunately, I avoided the opportunity to learn about these engines. My
father ran some
3 cylinder 2 stroke diesels in earth moving equipment some years ago and was
very happy with them. I believe they were turbocharged, but am not certain.
They may have started with a pony engine but again am not certain.

Can you fill me in on the details?

[Pete Schaefer]

The DeltaHawk uses both an electrically driven supercharger for starting and
low-rpm operation, plus a turbocharger for the usual stuff.

"Max Kallio" > wrote in message
om...
> How about supplementing a centrifugal turbocharger with a high speed
> electric motor to create boost needed for starting and to enhance
> boost at low rpm?

[Heywood]

Nope, the Deltahawk uses a traditional Roots belt-driven blower for
starting and low-rpm operation.

[Bill Daniels]

This actually makes sense. Electric motors have become much more powerful
for their weight. In the case of a two stroke diesel, electric boost would
only be used to get the engine running on the turbocharger. Thereafter,
it's unlikely to be needed except for an emergency air-start. Since the
power of the exhaust turbine exceeds what is needed for the compressor at
cruise power, the electric motor could become a generator. This rig is
likely to be simpler and lighter than a blower/turbocharger in series.

Bill Daniels

"Max Kallio" > wrote in message
om...
> 2-stroke diesels need compressed air for starting the engine, so the
> turbo (exhaust driven centrifugal supercharger) is out of a guestion
> and it produces very little boost at low rpm anyhow.
>
> How about supplementing a centrifugal turbocharger with a high speed
> electric motor to create boost needed for starting and to enhance
> boost at low rpm?
>
> This would pretty much eliminate the turbo lag and actually help suck
> the exhaust out of the cylinder at low rpm.
>
> When the rpm rises, the electric motor could disengage or perhaps even
> work as an auxilary generator.
>
> Also, if the turbo has some problems, the electric motor could be used
> at full power to help the turbo to spin and create boost at least for
> the time it takes to land safely. Of course, the engine should be
> able to have enough power to stay airborne at least at low altitudes
> (if the load is not exeeded) even when the turbo fails completely.
>
> Links...
>
> www.turbodyne.com

[Matt Whiting]

Max Kallio wrote:
> 2-stroke diesels need compressed air for starting the engine, so the
> turbo (exhaust driven centrifugal supercharger) is out of a guestion
> and it produces very little boost at low rpm anyhow.

Why do two-stroke airplane diesels need compressed air for starting?
The Detriot two-stroke diesels used in trucks and off-road equipment
have never needed that.


Matt

[Pete Schaefer]

Yup, yer right. Just checked. Must be confusing the DH with another engine.

"Heywood" > wrote in message
ups.com...
> Nope, the Deltahawk uses a traditional Roots belt-driven blower for
> starting and low-rpm operation.
>

[Steve]

Max Kallio wrote:
> 2-stroke diesels need compressed air for starting the engine, so the
> turbo (exhaust driven centrifugal supercharger) is out of a guestion
> and it produces very little boost at low rpm anyhow.

Modern large 2-stroke Diesels (EMD 710 series for example) have a
mechanical drive to the turbocharger which spins it at low power
settings and it acts as a mechanical blower. As power settings come up
and exhaust volume increases, the turbine takes over and operates the
supercharger. Much more efficient than converting mechanical power to
electrical then back to mechanical again.

[Steve]

Don Stauffer wrote:

> Why not just have a small compressed air pump driven by gears from
> crankshaft or camshaft, with a tank to store a few "starts" full of
> compressed air? Seems like an easier fix than an electric driven
> compressor.
>


People should really study up on some of the things that have been done
with turbo- and super-chargers for the past 60 years before getting
carried away. For the last 20 years, for example, virtually all EMD
locomotive engines (2-stroke diesels) have used a hybrid
mechanical/turbo supercharger. At low power settings and during
starting, a sprag (overrunning clutch) spins the turbocharger from the
engine's own gear train, just like the old Roots blowers used to be
turned. But when the power is increased, the turbine takes over and
spins the compressor faster than the engine's drive, so the overrunning
sprag releases and the turbo is fully powered by exhaust.

Proven, simple, no silly mechanical-electrical-mechanical conversions to
go through. But the 2-stroke diesel is dead anyway. Conventional
4-stroke turbo-diesels are the present (except for ever-decreasing
production of EMD 710 engines) and the future of diesel power.

[Steve]

wrote:

> "Max Kallio" > wrote in message
> om...
>
>>2-stroke diesels need compressed air for starting the engine, so the
>>turbo (exhaust driven centrifugal supercharger) is out of a guestion
>>and it produces very little boost at low rpm anyhow.
>
>
> Unfortunately, I avoided the opportunity to learn about these engines. My
> father ran some
> 3 cylinder 2 stroke diesels in earth moving equipment some years ago and was
> very happy with them. I believe they were turbocharged, but am not certain.
> They may have started with a pony engine but again am not certain.
>

Almost certainly Detroit Diesel 3-71 engines. There are millions of X-71
series engines still in use (X denotes the number of cylinders, and
there may also be a "V" in the designation: a V-12-71 denotes a V-12
with each cylinder displacing 71 cubic inches; a V-6-92 denotes a V6
with 92 cubic inch cylinders). Detroit Diesel is no longer producing any
of the 2-stroke series new, but they still support them and probably
will for another 20-30 years because there were so many built from ~1930
to ~2000.

In most earthmoving applications, the 3-71 was not turbocharged, but all
x-71 engines were supercharged with a roots blower (they won't run
without it, being 2-stroke engines). Pony engine start was common on
equipment made in the 40s and 50s, but electric start was almost
universal by the 60s, with compressed-air start being common on marine
and fixed engines.

[Bob]

Why is the 2 stroke diesel dead?
I know little about diesels, just the obvious, like no sparkplug.

Bob

[Steve]

Bob wrote:

> Why is the 2 stroke diesel dead?
> I know little about diesels, just the obvious, like no sparkplug.
>
> Bob
>

High emissions and lower fuel efficiency compared with competitive
4-stroke diesels

In order to get emissions down, a 2-stroke diesel engine has to be
"overblown" so that an excess of fresh air is pushed through the
cylinder to drive out the exhaust gasses fully, but doing that wastes
mechanical power. So solving the emissions problem aggravates the
efficiency problem and vice-versa. And also, 2-stroke diesels have a
lot higher lubricating oil consumption rate than similar 4-strokes, and
that aggravates emissions too.

The EMD 710 is the only remaining locomotive 2-stroke, and is being
phased out by the EMD 4-stroke "H-series" engine. Detroit Diesel was the
biggest maker of 2-strokes for trucks, earthmovers, yachts, etc. and
they stopped 2-stroke production several years ago. And its been over 20
years since many 18-wheelers used Detroit 2-strokes anyway.
Fairbanks-Morse still builds their opposed-piston 2-strokes for a few
Navy applications and for stationary applications (flood control pumps,
backup generators, etc.) and will probably continue to do so, but that's
a pretty small market segment.

Since 2 NGs are aviation related, that is one area where the 2-stroke
*might* hang on longer because of its weight savings, but its ultimately
probably doomed there also.

[Kevin Bottorff]

Steve > wrote in :

> Bob wrote:
>
>> Why is the 2 stroke diesel dead?
>> I know little about diesels, just the obvious, like no sparkplug.
>>
>> Bob
>>
>
> High emissions and lower fuel efficiency compared with competitive
> 4-stroke diesels
>
> In order to get emissions down, a 2-stroke diesel engine has to be
> "overblown" so that an excess of fresh air is pushed through the
> cylinder to drive out the exhaust gasses fully, but doing that wastes
> mechanical power. So solving the emissions problem aggravates the
> efficiency problem and vice-versa. And also, 2-stroke diesels have a
> lot higher lubricating oil consumption rate than similar 4-strokes, and
> that aggravates emissions too.
>
> The EMD 710 is the only remaining locomotive 2-stroke, and is being
> phased out by the EMD 4-stroke "H-series" engine. Detroit Diesel was
the
> biggest maker of 2-strokes for trucks, earthmovers, yachts, etc. and
> they stopped 2-stroke production several years ago. And its been over
20
> years since many 18-wheelers used Detroit 2-strokes anyway.
> Fairbanks-Morse still builds their opposed-piston 2-strokes for a few
> Navy applications and for stationary applications (flood control pumps,
> backup generators, etc.) and will probably continue to do so, but
that's
> a pretty small market segment.
>
> Since 2 NGs are aviation related, that is one area where the 2-stroke
> *might* hang on longer because of its weight savings, but its
ultimately
> probably doomed there also.
>
>

exspecially since they are testing at least one rotary diesel, very much
lighter and quieter for unmaned small reconasinst planes. KB
--
ThunderSnake #9 Warn once, shoot twice
460 in the pkup, 460 on the stand for another pkup
and one in the shed for a fun project to yet be decided on