Paul
  I ran across this patent "Internal combustion engine with compounded
air compression"
what caught my eye was the application of the idea to a rotary engine in
Fig 3.  in the patent they are using a turbo charger and a rotary
compressor which is mechanically linked to the rotary engine.  Very
interesting and maybe a good approach as maybe the smaller rotary
compressor could be directly linked to the main engine and therefore no
need for a clutch assembly?  Anyway, wanted to see what you thought.

Mike C.

Looks interesting but I don't see how we can use it in an aircraft.
As a compressor it will suck more HP than a turbo charger.

Paul Lamar
--

I agree with that but I think the claim was that

"unexpected results were obtained when both sides of the rotary
Wankel-type unit were used as a compressor and driven by power from the
engine shaft.  At lower speeds of operation, the turbocharger delivers
no compression and all of the compression is provided by the rotary
compressor operating as a blower.  At mid-range speeds both turbocharger
and the rotary compressor contributed and develop an enormous
compression.  At High speeds, the turbocharger develops sufficient
compressed air to not only power the engine, but drive the rotary
compressor which operates as an air motor."

It was the last sentence that got me thinking about direct coupled
rotary compressors to the e-shaft with a set up like this.  Since we
operate mostly at higher speeds... do you think there is anything to this?

Mike C

I don't really know. I think it would need to be built to test it.


Paul Lamar

If I understood this right, on high speed, the rotary compressor acts as
a pneumatic turbo-compound transmission, fed by turbocharger turbine.

Direct coupling with friction planetary and proper impulse turbine
should yield better results on exhaust energy recovery. Interesting
note, though!

Cheers,
Petri

The trick of efficiency improvement of the turbo compound consists of having additional expansion of the gas transformed into mechanical power.
The exhaust gas turbine is doing the additional expansion. Quite classical.
The energy of the detent is used for compression in the case of a turbocharger.
The energy of the detent is used directly as mechanical power in the case of a turbo-compound.
It is usually interesting to do this with 2 expanders to combine power density and efficiency, hence Scania, Detroit Diesel and Volvo layouts.

Interesting to notice in this layout that the reversal of function from compressor to 'pneumatic motor' can arrange for power to flow from air intake compression to engine crankshaft.
I can agree with the philosophy.

So how is the rotary device giving in its compression function to have a detent function? That means that the curve in the PV diagram of the rotary machine rotates opposite directions for each configuration.

I wonder how something particular is done on the rotary 'compressor/motor' to change its function.
Is that rotary device equipped with controllable valves so that the amount of air going in is limited?
The patent does not describe this.

Anyone have an idea about this?

Randolph in Paris


For the new subscribers we have several videos on the subject.

http://www.rotaryeng.net/turbo-compound.html
http://www.rotaryeng.net/Oxford-640-4802.wmv
http://www.youtube.com/watch?v=6Po5jsrYMK4
http://www.youtube.com/watch?v=bkWbsO0C8x8

Paul Lamar