Electric motor assisted super- or turbocharger?

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

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?

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?

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

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

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

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.

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.

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.