IMPROVEMENTS IN ROTATORY STEAM ENGINES
Year: 1877

page_text: PROVISIONAL SPECIFICATION left by Joseph Cougnet at the Office of
the Commissioners of Patents on the 24th September 1877.
JOSEPH COUGNET, of Brussels, in the Kingdom of Belgium, Civil Engineer.
"IMPROVEMENTS IN ROTATORY STEAM ENGINES."
My Invention consists in the emprovements herein-after described in the con-
struction of rotatory steam engines.
Upon a suitable frame is mounted or formed a metal cylinder, the ends of which
are closed by suitable covers provided in the centre with stuffing boxes, through
which passes a rotatory shaft which traverses the said cylinder. Upon the said
shaft and within the cylinder is keyed or affixed the nave of a rotatory piston which
extends from the said nave to the inner surface, and from end to end of the said
cylinder, a tight joint between the piston and the ends and inner surface of the
cylinder being maintained by metallic packing consisting of blades or strips of
brass or other suitable antifriction metal let into slots formed in the sides and end
of the said rotatory piston, which blades or strips of metal are forced outwards
against the surface of the cylinder and cylinder covers by steam introduced into the
slots through suitable holes in the said piston. A tight joint is also maintained
between the nave of the piston and the cylinder covers by annular blades or strips
of antifriction metal let into annular slots formed in the ends of the said nave;
the said annular packing being pressed outwards in contact with the cylinder
covers by steam admitted into the said annular slots through suitable holes. The
face of the said rotatory piston is curved, and the rear part of the said piston is
curved from the top to the nave, being prolonged so as to form a cam surface to
act upon two obturating sliding plates which divide the steam cylinder into two
parts or chambers. The said obturating sliding plates which radiate from the centre
of the cylinder move in grooves or guides formed in the cylinder covers, and at
certain times retire into chambers formed to receive them on the outside of the
cylinder. Steam is admitted to the cylinder through a suitable channel formed by
a steam jacket round the upper part of the cylinder, and the steam is discharged
from the cylinder by channels formed by the steam jacket round the lower part of
the cylinder. On each side of the said cylinder is a steam chest with a steam port,
governed by a slide valve or other suitable means, and the cut off may be regulated

page_text: by any suitable means. The steam in the steam chests passes partly through
a channel to behind the obturating sliding plates so as to press them inwards. In
some cases, instead of there being. only one rotatory piston in the engine, two of the
said pistons may be used, one projecting from each side of the nave upon the
rotatory shaft. The steam is then admitted and discharged on each side of the
cylinder simultaneously.
The action of the engine is as follows:-The obturating sliding plates being both
closed, dividing the cylinder into two parts, steam is admitted between the face of
the piston and one of the said plates, and forces forward the said piston towards the
second obturating plate; meanwhile, the cam surface forming the back part of the
said piston in its rotation forces out the second obturating plate and causes it
gradually to retire into its chamber; the cam surface gradually filling the space
between the said plate and itself, and expelling any steam behind it through the
exhaust channel. When the piston has passed the second obturating plate the said
plate returns into position in the cylinder, and steam being admitted between it and
the piston, the same effect is produced as herein-before described, and the piston con-
tinuing its rotation, the same action is repeated.