Improvements in Rotary Engines and Pumps.
Year: 1896

page_text: Improvements in Rotary Engines and Pumps.
I, BENOIT DEMONT, of 21 Boulevard Poissonnière, Paris, in the Republic of
France, Engineer, 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 a rotary engine device which I have designed with the
object to ensure a reliable action and especially to increase its efficiency.
The rotary engine in question belongs to the class of engines, in which a
diaphragm or piston freely traverses the diametrical mortise of a shaft and moves
in a cylinder of a more or less elliptical or oval section. In motors of this kind the
shaft in question, placed eccentrically relatively to the cylinder is so arranged as
to be tangential to the said cylinder along one of its generatrices, and the orifices
for the admission and the exhaust are placed at each side and very close to this
point of tangency. These arrangements result in a strong counterpressure,
detrimental to the action of the engine and greatly reducing its useful effect.
Motors of this kind therefore have never proved a success by reason of the excessive
amount of steam required.
According to my invention and to avoid this defective condition the arrange-
ment of the shaft relatively to the cylinder, also the general form of the section
have been modified; moreover the admission and exhaust orifices have been
removed from the shaft and a particular form has been given them; finally a
mechanism for distributing the motor fluid has been added in such a manner as
to allow of the expansion of this fluid under special conditions.
Owing to these modifications or improvements the rotary engine device above
explained has a far higher efficiency than that formerly yielded. This has on the
other hand been proved by comparative experiments made with two motors (the
original system and the improved system) of equal dimensions.
In order to afford a clear understanding as to the nature of the modifications
applied and the industrial result of which is unquestionable, the following des-
cription is given with reference to the accompanying drawings.

page_text: Figure 1 is a vertical section of a rotary engine constructed according to my
invention.
Figure 2 a horizontal section on the line 2-2 of Figure 1.
In the same way as heretofore the machine thus represented, comprises a
cylinder A, an eccentric and mortised shaft B and a flat piston C engaging with
the mortise of the shaft and displaced therein according to the different positions
it occupies in the cylinder under the influence of the motor-fluid.
The essential differences are the following:
1. Modification of the place of the mortised shaft and different section of the
cylinder.
2. Modification of the place for the admission and exhaust orifices for the motor
fluid.
3. Distribution of this fluid by the aid of a simple cock actuated by the shaft
and producing a more or less prolonged expansion of the said motor fluid.
The shaft B, instead of being tangential to the interior surface of the cylinder A
enters this latter more or less, as indicated in Figure 1. From this fact results a
more or less extensive contact a b which ensures a tighter closure for the joint
between the shaft and the cylinder. This contact according to the extension a b
has for its result to render a corresponding and opposite portioned of the
cylinder concentrical to the shaft and counteract upon this extension any sliding
motion of the piston C in the mortise of the shaft. The sliding motion of this
piston can only take place between the points be and d a. In short, it is evident
that the primitive shape, which is more or less oval or elliptical, is reduced to that
of two concentrical differential arcs a b and c d connected by the curves be and da,
which compel the piston, when in motion in the direction of the arrow .r, to be
displaced longitudinally in the mortise, first in direction of the arrow 2, and
then in the opposite direction.
The orifices for the admission (e) and the exhaust (f) are no longer arranged near
the point of contact between the shaft and the cylinder but at such a point that
the exhaust of the motor fluid which has just produced its effect, commences to take
place at the same moment when the introduction of a fresh quantity of the said
motor fluid commences. This arrangement corresponds to the initial position of the
diaphragm or piston r, that is to say to the position which this latter occupies when
its two extremities are symmetrical relatively to the shaft B, as represented in
Figure 1 of the drawing. In this figure it is seen, in fact, that the inlet orifice e
is on the point of being uncovered by the piston C turning in the direction of the
arrow, and that this is the same with regard to the exhaust orifice f. It results
therefrom that no back pressure whatever is possible in the cylinder and that the
admitted steam produces all its useful effect."
It will be observed that the inlet orifice e is slightly curved toward the piston
that is to say in the rotary direction of the latter so as to better utilize its force of
expansion, the vis viva which it possesses. It will be likewise remarked that tho
exhaust orifice f extends into the cylinder by an incision g the object of which is
to ensure the communication between the said orifice and the cylinder portion
which is situated beneath the piston, when this latter has passed the orifice. In
this manner this cylinder portion continues to be exhausted until the piston arrives
at the point a of the cylinder and at the time when the cylinder portion above the
piston is already in communication with the exhaust orifice f.
When the piston C occupies the horizontal position (Figure 1), the cylinder A is
divided into three compartments. The compartment 1, in which the motor fluid
is about to be admitted as soon as the piston C has uncovered the orifice e; the
compartment 2, in which the previously introduced motor fluid acts: and the com-
partment 3 representing the exhaust chamber. These three compartments exist
up to the moment when the piston takes up the position indicated in dotted lines.
From this moment that is to say during the time when the piston passes from
the point a to the point b or from the point e to the point d, there are only two

page_text: compartments; one receiving the motor fluid, the other allowing of the exhaust
of the fluid which has previously acted.
The distributing cock D is arranged transversely to the orifice for the admission
of the motor fluid; the rod h of its plug is connected to the shaft B to which it is
parallel by means of a crank i keyed to the said rod, of a connecting rod j and
of a crank disc k keyed on the said shaft. This connection transforms the circular
novement of the shaft 3 into an angular alternating movement of the plug of
the cock D so that the aperture through said plug is alternately set in and out of
line with the conduit or admission orifice e. In this very simple manner, the
motor fluid is introduced only during a fraction of the active course of the flat
piston, and an expansion results therefrom, the duration of which can be more or
less prolonged. For this purpose it is sufficient to either vary the radius of the
crank i or that of the crank disc k, and this in any suitable manner.
I have hereinbefore described a single acting machine but I may obtain a double
acting apparatus by grouping two cylinders similar to A upon the same shaft,
but reversing the admission and exhaust orifices.
I may also obtain the reversing motion of the machine by joining to each side
of this latter an admission orifice and an exhaust orifice and by arranging upon
each orifice stop valves which would be capable of being so connected as to act
thereon by the aid of a single operation, and so as to set in action one or the other
set of admission and exhaust orifices.
It is clear that the motor may he provided with a foundation or platform
arranged at any appropriate place and which would serve to fix it to the ground
or to a vertical wall. The direction of the nozzles of the admission and exhaust
orifices may likewise be of any kind. A governor of any kind and suitably
actuated by the shaft B may act upon the distributing valve for the motor fluid.
The machine may finally he constructed in all sizes and of any suitable metals. It
may also be worked by any motor fluid (steam, compressed air, water, gas and
the like) or it may also be utilized as a pump for sucking and forcing fluids of
all kinds.
Having now particularly described and ascertained the nature of my said invon-
tion and in what manner the same is to be performed, I declare that what I
claim is:-
1. An improved rotary engine capable of serving as a pump, comprising: a
cylinder, au eccentrically arranged and mortised shaft and a flat piece forming a
piston engaging with the mortise, of the said shaft, and the characteristic points
of which are: (a) the shape of the cylinder formed by the aid of two concentric
differential ares arranged opposite one another and connected by curves fixed by
the successive positions which the piston can occupy from one are to the other:
(b) by the entering of the shaft into one cylinder portion; (e) by the position of
the admission and exhaust orifices, which position is such that the steam which
has just produced its effect, is exhausted at the precise moment when a fresh quan-
tity of steam is introduced so as to avoid any back pressure; (d) by an incision
prolonging the exhaust orifice for completing the action of exhausting, without
hack-pressure, the compartment of the cylinder which lies beneath the piston when
this latter has passed beyond the exhaust orifice: by the method of distribution of
the fluid by the aid of a simple cock so actuated by the motor shaft as to produce
an expansion adjustable at will. The whole arranged as has been specified with
reference to the drawing.
2. In rotary engines comprising a piston engaging with the mortise of a shaft
eccentrically arranged relatively to the cylinder of a more or less elliptical or
oral shape and in which the said shaft is tangential to the cylinder, the special
arrangement of admission and exhaust orifices in such a manner that the exhaust
of the fluid which has just produced its effect, commences at the precise moment
when a fresh quantity of motor fluid is admitted, and that by an incision of the

page_text: exhaust orifice the said exhaust continues until the piston has arrived at the point
of tangency. This arrangement having for its object to avoid back-pressure and
to ensure a higher efficiency than that attained up to the present, as hereinbefore
specified.
Dated th: 10th dom
1900
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.