IMPROVEMENTS IN THE CONSTRUCTION OF ROTARY STEAM ENGINES
Year: 1877

page_text: PROVISIONAL SPECIFICATION left by James Apperley at the Office of the
Commissioners of Patents on the 3rd March 1877.
JAMES APPERLEY, of Dudbridge House, near Stroud, in the County of Gloucester;
"IMPROVEMENTS IN THE CONSTRUCTION OF ROTARY STEAM ENGINES."
This Invention relates to rotary engines in which the steam or other elastic fluid
is superheated during its passage to and through the engine, and the impulsive force
of the elastic fluid moving with velocity is utilized. To this end the engine and
superheater are combined in one, and consist cheifly of an outer stationary casing
supported upon a suitable bed plate or foundation and an inner revolving drum or
cylinder mounted upon an axle carried from the bed plate.
The outer casing is composed of two annular or serpentine concentric channels or
chambers or passages, the inner one being the steam superheating chamber, and the
outer one forms a part of the flue for the passage of the heated combustible gases, or
it may be the chamber in which they are consumed.
The entrance pipe or passage for conducting the steam from the boiler to the
superheating chamber is commanded by a rotary or other valve operated automati-
cally. The inner periphery of the annular steam superheating chamber is formed by
a series of partitions arranged tangentially, between which are parallel passages
leading to the metal cylinder or drum, which-is so mounted as to be capable of free
rotation within this outer casing. This metal cylinder is provided with a continuous
spiral or volute passage, which is composed of a series of alternate enlargements or
contractions, triangular or pear-shaped in cross section. The opening or mouth of
this passage is at the periphery of the cylinder, and is carried around the cylinder a
sufficient number of times (approaching the centre) to obtain the desired result, viz.,
the expansion or condensation of the steam. The inner or open end of this spiral
passage, which is near the centre of the cylinder, commanded by a rotary valve or
cock, and may open out into a cooling chamber or condenser, so as to obtain the
additional aid of a vacuum. The steam entrance and exit valves are operated
automatically by means of cams or excentrics on the axle of the cylinder or drum,
or in any other suitable manner.
In starting the engine the communication between the furnace flue and the
concentric heating flue of the engine is to be opened, or when the gases of combus-
tion are burnt therein they are to be first lit, so as to heat the engine and prevent
Davies 9,71

page_text: condensation of the steam on its first admission; the ordinary saturated steam is
then to be freely admitted into the annular chamber of the case, and passing
by the tangential passages, will enter in at one or more of the ports leading to
the spiral steam passages, and in its rush through them to the condenser or open air
will impinge in succession on the heads of the triangular enlargements of the passage,
and thus impart a rotatory motion to the drum or cylinder by a rapid succession of
impulses.
When the outer case becomes heated by the passage through it of the combustible
gases or the combustion of gases therein, the entrance and exit passages to and from
the engine are to be allowed to be acted upon automatically; and the mechanism
provided for this purpose is so arranged to be capable of adjustment, both as to
the number of times the valves are to be opened during one revolution of the drum
and the duration of time they remain open, so as to obtain the maximum effect due
to the expansion of the superheated steam.
In some cases it may be desirable to provide several entrances or mouths by which
the first of the spiral passages may be fed from the tangential passages of the
superheating chamber; one way of attaining this object is to cut narrow grooves in
the periphery of the cylinder of a depth sufficient to enter or cut through some
portion of the pockets leading to the first spiral passage. These grooves are to be of
such a width as to obtain a wire drawn action of the steam in its endeavour to enter
the said spiral passages, and this frictional action of the steam will be necessarily in
the direction of the rotation of the drum.
Another manner of constructing the spiral passages is to commence at three, four,
or more points in the periphery of the drum, and carry them round spirally, these
passages being provided with four or more exit passages sideways of the cylinder.
In this case the steam superheating chamber is to be divided into three, four, or
more divisions (corresponding to the number of spiral passages), and each division
is provided with a steam admission valve. Or the spiral passage may be so formed
that its sectional area is largest at the periphery of the drum, and gradually tapering
to its end near the centre of the cylinder. The opening or mouth of this spiral
passage will thus receive the rush of highly heated elastic gases, as it moves in
succession past the mouths of the inclined partitions of the inner superheating
chamber or channels; the steam in its passage through the first portion of the
spiral passage will be caused by friction at the sides of the passage to carry round
the drum.
To further aid in effecting this object the frictional surface of the interior of this
spiral passage may be increased by placing within the same corrugated plates, stops,
studs, or supports. The steam, as it parts with its heat, becomes more dense in its
passage through the decreasing sectional area of the spiral passage, and will thus
provide itself with an elastic "pillow" and an increase of friction as it is forced
through the final coils of the spiral passage. The force of the steam will thus be
utilized before it issues from the opposite end of the passage into the exhaust or
'cooling cylinder.