http://www.google.com/patents/US7753036

This is a comprehensive web site on the rotary turbo compound.
Most of the recent patents are assigned to Pratt & Whitney.
 One of the persons named as an inventor was on the news letter
for years back in the late 90's and early 2000's. That is Jonathan Lauter.

I suspect this is an attempt to keep somebody from making
them, certifying  them and selling them competing with the PT6 :-)
Some of the patents run out in 2017.

You can use http://www.pat2pdf.org/ to get free copies
of the patents

Here is a short list. You can cut and paste them into pat2pdf

5471834
7753036
7775044
20090007882
04074655

Attached is the most relevant patent.
Also a screen capture of some of the patent text
mentioning the Mazda rotary :-)

Much of this was before the Iannetti silicon nitride seals increased
the apex seal life to 20,000 hours.

Paul Lamar

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