An Improved Rotary Engine, Adapted also for Use ás a Pump for Liquids and Gases, Blowing Purposes, and as a Meter for Liquids.
Year: 1888

page_text: An Improved Rotary Engine, Adapted also for Use ás a Pump
for Liquids and Gases, Blowing Purposes, and as a Meter for
Liquids.
[, JOHANNES SELWIG of Braunschweig in the German Empire, Engineer, do hereby
declare the nature of said invention for "AN IMPROVED ROTARY ENGINE, ADAPTED
ALSO FOR USE AS A PUMP FOR LIQUIDS AND GASES, BLOWING PURPOSES, AND AS A
METER FOR LIQUIDS," and in what manner the same is to be performed to be
particularly described and ascertained in and by the following statement :-
The rotary engine or apparatus of this invention is shewn in the accompanying
drawing, Figs. 1 and 2 being vertical sections thereof taken through the engine at
right angles to one another through lines wx and y respectively. It consists
mainly of three parts, viz.: the working body A which rotates with its shaft a through
which power is transmitted; the obturator B capable of turning freely on the fixed
axis band driven direct without any intermediate outside gearing by the working
body A; and the casing C which hermetically closes the two other said parts on all
sides in the plane y- of their axes of revolution.
The working body A has the form of a so called crown wheel, its teeth d being on
the front side of, and in one pieco with the cylindrical disc s connected to the shaft a,
the outer circle being the root circle and the inner circlothe point circle of, the
teeth..
The obturator B has the form of a spur pinion wheel of similar pitch and width
of teeth but with a smaller number of teeth than the crown wheel A in which it
engages. The fixed axis b on which it turns is in one piece with the front side c¹ of
the casing C or is fixed to the same. The said wheels may have any suitable number
and form of teeth, probably the best proportion would be that A should have from
five to seven and B three to four teeth. The teeth e of the obturator or pinion B are
of such a depth that when the wheels are working there will always be one, if only
a small portion of one tooth point situate at the sides on the outer wheel circle of
the wheel A or path of the root surface of the teeth d. In order that this may be the
case the distance f of the two points of intersection of the outer wheel circle of the
wheel B with the outer wheel circle must be greater than the distance i of the outer
edges of two proximate teeth e of the wheel B.
The casing C which hermetically encloses on all sides the wheels A B in the
plane y consists of the two outer parts c¹, c²; of an internal part c³ and of the
two side parts c, c, which parts are collectively fixed together. The part c¹ encloses

page_text: the path of the outer points of the teeth d of wheel A for the length on the side
opposite to the wheel B, which length is greater than the distance between the two
nearest outer edges of two proximate teeth d; the opposite part ² encloses that part
of the path of the front surfaces or points of the teeth e which lies outside the wheel
circle for the length falready referred to. The part c³ forms a prismatic projection
penetrating from the front side part of the casing to the inside of the wheel A,
which projection encloses with its upper surface the internally situated part of the
path of the front surfaces or points of the teeth e for the length i, which length is
greater than the distance ; on its lower convex surface, it, on the other hand
encloses the path of the inner surfaces of the teeth d for a length g' which must be
greater than the distance between the inner edges of the teeth d. The front side
part of the casing is touched by the front side surfaces of the teeth d as well as
by the wheel B. and it serves simultaneously as a support for the axis and pro-
jection the back part of the casing comes against the back of the disc its
circular central orifice having the shaft a of the wheel A mounted in it.
9
It will now be clear that the two spaces M, N, respectively on the left and right
hand of the wheels are not in direct communication with each other, in whatever
position they may happen to be. They are perfectly separated from each other, the
wheel B (the obturator) effecting the closure between the parts c², c³, c, of the casing
and of the disc s, whilst the space between the parts c¹, c³, c, and disc s is filled up by
one or more of the teeth d of wheel A. Supposing now the spaces M, N, to be
charged with a liquid and that in one of them, M for instance a higher pressure is
present than in the other N, there will then no doubt be a pressure exercised against
the wheel B in the direction of from M to N but not such as to cause it to revolve as
its resultant always passes through the geometrical axis of the wheel B. On the
contrary, those of the teeth d of the wheel A which are in, or pass the circular space
between the parts c and e³ of the casing are subjected on one side to a pressure
from M towards N, all the others being perfectly counterbalanced, especially also the
tooth which partly filling up the clearance between two teeth of the wheel B returns.
from the space N to the space M. The wheel B receives the pressure which it would
otherwise receive in the direction of from M to N. By reason of the said one sided
pressure against the teeth d, the wheel A (working body) and with it the wheel B
will now be caused to revolve in the direction shewn by the arrows. Power may be
given off from its shaft a, that is to say, the machine would then work as a motor.
The volume of liquid which upon each revolution of the wheel A will pass out of the
space M into the space N is equal to the volume or capacity of the space, travelled
through by one tooth of the wheel A upon one revolution of this latter.
The machine is therefore also adapted for use as a meter for liquids upon the shaft a
being placed in connection with a counting or numerating apparatus. Inversely when
the wheel A by turning its shaft a in the direction of the arrows, is set in motion, the
aforesaid quantity of liquid will, at each revolution of the wheel A, be delivered
from fe space M into the space N, however high the pressure in these spaces
may be.
The machine may also be used as a pump for liquids, gases and as a blower.
The advantages it presents, and which probably none of the known rotary engines
or machines collectively possess, are as follows :-
1. The direct transmission of the power to and from the working body whereby
loss of power by friction is diminished.
2. The perfect relief from load of the obturator revolving without any expenditure,
of power, as well as the method of driving the same direct by the working body,
rendering outside gearing unnecessary.
3. The closing in of the several working parts by their contact surfaces in the
manner described which allows of the machine being worked under very high pressure,
and has for result a very high useful effect.
4. The non-existence of a dead point; the capability of working the machine in
either desired direction, together with the perfectly regular velocity of the liquid
in the delivery and discharge pipes, rendering unnecessary the use of air vessels.

page_text: 5. The perfectly equal distribution of the weights of the two rotating parts around
the axes of rotation, thus allowing of the use of very high velocities.
G. The extremely simple construction of the machine and the easy and inexpensive
production of the working and obturator bodies by reason of their small number of
teeth.
Figs. 3 to 7 shew the machine in its application as a pump or hydraulic motor,
Fig. 3 being a section crosswise thereof through line u- of Fig. 4. The wheels
are here in the position where the middle of a tooth e touches the middle of part c³
of casing. Fig. 5 is a section taken parallel to that of Fig. 3 through line u'-v²,
the wheels being in the position where the part of of casing is touched by two teeth
of the obturator between which, one tooth of the working bo ly is entered. It
corresponds to the position shewn in Fig. 1. Fig. 4 is a longitudinal vertical
section taken through line of Fig. 3, that is, through the middle of the
axes a, b, and casing C. Figs. 6 and 7 aro perspective views of the working body A
and obturator B.
The same letters of reference indicate the same parts as those used in Figs. 1
and 2.
In order that the teeth d, e, may be very simple and of easily made shape, the
wheel A has twice as many teeth as the wheel B, namely the one six and the other
three; they are of a pointed shape, the cross section of the teeth e being as shewn
in Fig. 5 in the form of a circle cut off on the outer side, so that their flanks form
cylindrical surfaces, whilst the cross section of the teeth dis oblique at the sides,
curved at the base and truncated at the point, their sides or flanks therefore being
perfectly plane surfaces.
As the turning of the obturator by the working body, requires theoretically none
at all, and practically only very little power, it is not necessary for the teeth d, e, to
gear into each other in the whole of their width; it is sufficient if they are of the full
cross section (as shown in Fig. 5) for a portion only, say from one quarter to one
third of their width, and preferably so at both ends, for which purpose they are formed
with recesses o or p (Figs. 3, 6, 7) so that at this part the teeth e are tee-shaped and
the teeth d somewhat after the same form.
This reduction of the cross sectional area of the teeth has further an important
object, namely, to reduce the frictional resistance when liquids are being passed through
the machine, especially at high velocities.
The casing C of the machine consists of a cylinder c³, c², closed at both ends by two
covers screwed or bolted thereto. The suction and delivery pipo M, N, aro in commu-
nication with the upper part c² of this cylinder sidewise, which part is bored out to
the size of the outer diameter of the working body; the upper part c² being bored
out to the diameter of the obturator and alway in contact with this latter by one
or two of its teeth. The front cylinder cover e carries the shaft 6 of the obturator
and also the prismatic projecting part 3 of sickle or crescent shaped form, the lower
convex side of which, comes in contact with the inner surfaces of the teeth d. The
back cylinder cover is provided with a stuffing box through which passes the
shaft a of the working body, carrying on its outer end, a belt pulley K for the
transmission of power. The obturator B, instead of turning round a fixed axis b
like the working body, may have an axis or shaft turning with it which would then
be mounted in the cover and pass through a stuffing box. It could be employed
for the transmission of power instead of the shaft a, but such a method of construction
is not recommended as the friction resistance in the machine is thereby augmented.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim, is :-
In rotary engines or machines of the kind referred to :-
1. The working body A in the form of a crown wheel with internal teeth revolving
in the axis of a, for the purpose specified substantially as described and shewn.
2. The obturator B having external teeth for gearing into the working body A and

page_text: turning on an axis eccentric to that of A for the purpose specified substantially as
described and shewn.
3. The casing C which, in the plane y perfectly encloses the two bodies or
wheels A, B, on all sides, and having a projecting part c³ and axis b for the purpose
specified substantially as described and shewn.
4. The combination of wheels A B with their number of teeth in the proportion
of 21 and of the cross sectional form shewn in Fig. 5, the sides or flanks of tho
teeth d being flat or even planes and those of the teeth e cylindrical surfaces, for the
purpose specified substantially as described and shewn.
5. The use in wheels A, B, of teeth having in one portion of their width or length
the full cross section for working purposes and in another portion of their width or
length a smaller cross sectional area for the purpose specified substantially as described
with reference to Figs. 3, 6, and 7 of the drawing.
6. The general construction and combination of parts constituting the engine or
machine for the purposes specified substantially as described and shown.
D: 104
T
1. 1000
CAPITAINE & VON HERTLING,
89, Chancery Lane, London, W.C.,
•
Agents for the Applicant