Improvement in Rotary Steam Engines.
Year: 1899

page_text: Date of Application, 6th Nov., 1899-Accepted, 16th Dec., 1899
COMPLETE SPECIFICATION.
Improvement in Rotary Steam Engines.
I, HANS THORMEYER, of Bingartesmuhle, Hersfeld, in the German Empire,
Manufacturer, do hereby declare the nature of this invention and in what manner
the same is to be performed, to be particularly described and ascertained in
and by the following statement.
This invention relates to expansive rotary steam engines with sliding piston
vanes and my improvement consists in so forming the steam chambers that the
vanes at the beginning of the admission of steam move outwards instantaneously
and present large surfaces to the live steam and maintain these surfaces uniform
to the end of the admission, and that during expansion these surfaces are in-
creased so as to present a laiger surface to the steam pressure as the latter de-
creases, and thus obtaining a uniform turning pressure during the greater part
of the stroke and utilizing the expansive power of the steam to the greatest
advantage
This improved construction of a rotary steam engine is represented on the
drawing appended hereunto, in which Figure 1 shows a longitudinal and
Figure 2 a transveise vertical section of the engine
In the casing a which is closed at the sides by the covers b containing the
shaft bearings, rotates a shaft c and a disc d fixed thereon in which the vanes e
can slide radially These vanes are pressed by any suitable usual means, for
instance by strong helical springs as shewn on Figure 1, against the outer wall
of the casing and follow the outline of the steam chambers f, of which there
are preferably two, with abutments touching the disc between them
The ports of the steam chambers in which the admission of steam takes place,
ale concentric with the disc d, by which means from the commencement to the
end of the admission period the area of the vanes or pistons subject to the stean.
pressure remains the same, and they are formed at their front ends with inclined
surfaces , on which the ends of the vanese slide outwards at once, so that
immediately at the start of the admission a larger area of the vanes is exposed
to pressure than is usual in the expansive 1otary engines of this class hitherto
made The clearance spaces are reduced to a minimum, as the shape of the
ends of the vanes can be made to correspond exactly with that of the inclined
surfaces on which they slide outwards After the vanes have passed the con-
centic part of the casing and the steam inlet is closed, the expansive force
of the steam propells the vanes further, and the steam chamber is made crescent
shaped, so that the vanes protrude further out of the disc d up to the middle
of the crescent shaped part and offer to the decreasing pressure of the steam a
continually increasing area, whereby the pressure on the vane remains vitually
uniform from the commencement of the steam admission up to this point.
Preferably two steam chambers and three vanes are arranged as shewn on the draw-
ings, so that when the vane in one chamber arrives at about the middle of the
crescent, the preceding vane in the other chamber 18 under full pressure and the
space enclosed between it and the third vane begins to open the exhaust ports.

page_text: The live steam arrives through the pipe g and passes through porta h arranged
in the casing to the cocks or their equivalent arranged in the abutments of the
casing which are governed to open and close as required by any suitable known
valve gear. Other ports m conduct the exhaust steam to the port k and pipe n
connected thereto
The length of the concentric high pressure spaces is proportioned suitably
to the initial pressure of the steam and they are made the shorter the higher
this pressure 18. The steam consumption is consequently low as the full work
begins with the moment the admission 18 opened and only ceases when the ex-
pansive power has been fully utilized The used up steam remains enclosed
between two vanes till the leading vane has passed the exhaust port and then
is expelled by the following vane. As the exhaust ports are at the ends of the
steam chambers and are made very large, there will be no back pressure
Having now particularly described and ascertained the nature of my
invention and in what manner the same is to be performed, I declare that what
I claim is:
1 In rotary expansive steam engines with sliding vanes, the formation of the
internal walls of the casing of such a shape that the area of the vanes exposed
to the steam pressure remains constant during the admission of the steam
and increases during the expansion, substantially as and for the purpose herein-
before described and illustrated by the drawings
2 In rotary expansive steam engines with sliding vanes, the formation of
the walls of the steam chambers concentre with the disc carving the vanes
for the length of stroke during which steam is admitted and crescent shaped
for the remainder of the stroke of the vanes, substantially as herein before
described and illustrated by the drawings
Dated this 2nd day of Noromho 1800
R J. URQUHART CE,
Chartered Patent Agent, Manchester & Liverpool