IMPROVEMENTS IN ROTARY PUMPS, METERS AND MOTORS
Year: 1884

page_text: I. EMIL OEHLMANN, Engineer of 70 Dresdenerstrasse, Berlin S Prussia German
Empire do hereby declare the nature of said invention for "IMPROVEMENTS IN
ROTARY PUMPS, METERS AND MOTORS" to be as follows:-
The object of this invention is to provide a machine of such construction as
to serve as pump, meter or motor, and in which two pistons revolve together in a
drum each piston consisting of several wings, of which each one of the one piston
works with the corresponding one of the other piston, the two pistons oscillating
in each other. By the turning of the driving axle once each piston is periodically
revolved faster forwards, and the other piston during this quicker movement corrc-
spondingly slower. Hereby contractions and enlargements of the spaces between
the single wings of the pistons take place, so that at as many places in the drum
as where there are wings in, if the apparatus is used as a pump, for instance, it
sucks in and forces out fluids in a much better manner than those of previous or
ordinary construction.
Both pistons are alike, and the individual wings of both pistons pass in between
each other. The wings of both pistons revolve close to the inner walls of the drum
or cylinder and are connected on the one side with a disc which however may also
be omitted. Both the pistons are by suitable gearing made to move during their
revolution alternately faster and slower. Whilst one (say four winged) piston, the
other (four winged) piston moves slower. If for instance the drum serves as a water
pump the water entering by four inlet ports in the circumference of the drum which
communicate with an annular inlet passage around the cylinder or drum flows into
the four smaller sector shaped intermediate spaces between the wings whilst the
water which had previously been sucked into the other four sector shaped spaces, the
contents of which during the quicker revolving of the wings of one piston, are now
reduced, will be forced out through other similar outlet ports into another annular
passage next to the first named annular passage. These annular passages are pro-
vided with pipes for the suction and delivery. When the wings of the one piston
come up to those of the other piston the latter begin to move quicker, whilst the
first piston lags behind, the previously filled spaces empty themselves and the
emptied spaces are again filled. During this however both pistons always move so
far forward that the following inlet or outlet ports let the water in or out for the
spaces required. These openings are set somewhat out of a line with each other.
The described alternately quicker and slower movement of the pistons during their.
Price 1

page_text: revolution produces a continual suction and delivery of the water by a continuous
revolution of the driving axle or shaft. This shaft revolves in bearings or standards,
and each end of the shaft may be provided with a pulley by means of which motion
is communicated to the shaft.
From this continued revolution of the shaft the described periodical slower and
quicker revolving motion of the winged pistons is attained by means of gearing on
each side of the cylinder (or it may be only on one side). On each side of the drum
the shaft is provided with an internally toothed wheel which each gear with a
pinion which is inovably fixed on the crank pin of a crank which is fastened to
the piston shaft and connected by means of a crank or eccentric on the same crank
pin and by a connecting rod from the said crank or eccentric to a crank which is
secured to the hollow nave or boss of a rotating winged piston. The tooth pinion
on the left side is in its highest position when the corresponding tooth pinion, on
the right of the drum is in its lowest position. When one crank is moved to the
right, the axle of the tooth pinion fixed on to the crank (while the pinion rolls
along and gears into the teeth of the internally toothed cog wheel) goes to the
left. Every point of the pitch-line of the pinion therefore describes a hypocycloid
and the pin of the crank moving there with makes a similar curve. The connecting
rod thereby swings on pin at the outer end of the crank on piston nave and as now
the movement of the crank pin tallies tolerably with the swing curve of the con-
necting rod, it will be seen that during the first periods of the movement of the
pinion and crank of the same, the revolution of which was communicated from one
crank to the other is retarded. If, on the other hand the crank is in the opposite.
position the crank on the piston nave will turn quicker and it follows that during
one half of the revolution of the pinion a retardation takes place, and during the
other half an acceleration. The amount of the retardation or acceleration alters
at every point, so that the before described periodical different movement of both
pistons takes place. The accelerating or retarding motion of the one piston towards
the other takes place four times during one revolution of the driving shaft. Whilst
the progressive crank pin is in the first half of the cycloidic path, the piston remains
behind while the other piston moves on ahead. And on the contrary whilst the
crank pin is on the second half of the cycloidic path the one pistou goes on ahead
and the piston remains behind.
The toothed wheel mechanism can be modified for driving the multiple winged
piston in several ways. In one arrangement for instance the driving axle or shaft
turns a star wheel and this sets a tooth pinion (half the size of the preceding)
into a velocity double as great as that of the star wheel. On the axle of the pinion
there is fixed a star wheel of double the diameter of the pinion which latter com-
municates motion to tooth wheels of like diameter which are mounted on a common
boss and are revolved round the driving axle at double as many revolutions as
the wheel which drives them.
Naturally the transmitting gearing of the wheels may be varied.
Instead of four wings to each piston any other number of wings may be used
without altering the nature of the invention, only the relative diameters of the
wheels and the length of levers or cranks will have to be varied accordingly.
The apparatus may also instead of working as a pump act as a motor, by letting
compressed air or other fluid under pressure enter the annular passage for the
-pressure side, and without using any slide or other valves. As the oscillating
notions of both pistons are quite similar, one piston may be worked from the
working mechanism of the other as long as the phases of the motions change
properly.
According to such a modification a lever is fixed on the engine shaft and
carries a pinion which can turn freely on a fulcrum pin and rolls on the outside
of a tooth wheel (like the so called sun and planet notion). The tooth wheel is
fixed on the shaft bearing. For a four-winged piston the pinion is one fourth
of the diameter of the wheel. Each part of the pitch line of the pinion describes
four epicycloids with the circumference of the wheel as basis. A short crank is

page_text: fixed on the pinion fulcrum and its crank pin likewise describes four such
epicycloids. A connecting rod from the crank pin to a block which works in guides
on the lever, causes the block to work four times inwards and four times outwards
for each revolution of the lever. To each side of the block is jointed a link which
links are jointed each to a lever respectively fixed on the shaft or shaft sleeve of the
two pistons, so that these latter are caused to swing backwards and forwards in
each other as in the previous cases, and so that the liquid is drawn in and forced
out at four different points of the circumference of the drum.
Or again, according to a modification a lever is also fixed on the shaft which is
driven by a strap pulley. The lever carries a pinion which as before rolls round a
four times larger tooth wheel fixed to the bearing of the shaft and describes four
epicycloids and so also a crank on the pinion's fulcrum pin. A connecting rod from
the crank pin transmits oscillating motion to a triangular piece which turns on a
fulcrum pin on the lever and from one pin transmits oscillating motion to a crank
or lever on the shaft of one of the pistons, and from another pin transmits
motion by a link to a lever or crank on the nave sleeve of the other piston, so
that these two cranks swing backwards and forwards and the pistons accordingly
also.
i

page_text: I, EMIL OEHLMANN, Engineer of 70 Dresdenerstrasse, Berlin S Prussia German
Empire do hereby declare the nature of said invention for "IMPROVEMENTS IN
'ROTARY PUMPS METERS AND MOTORS" and in what manner the same is to be
performed to be particularly described and ascertained in and by the following
statement:
The object of this invention is to provide a machine of such construction as to
serve as pump, meter or motor and in which two pistons revolve together in a
drum each piston consisting of several wings, of which each one of the one piston
works with the corresponding one of the other piston. By the turning of the
driving axle once each piston is periodically revolved faster forwards, and the
Hereby con-
other piston during this quicker movement correspondingly slower.
tractions and enlargements of the spaces between the single wings of the pistons
take place, so that at as many places in the drum as where there are wings in, if
the apparatus is used as a pump, for instance, it sucks in and forces out fluids in a
much better manner than those of previous or ordinary construction.
As shown in the accompanying drawings Figure 1 is a side elevation and in
Figure 2 a cross section of the drum and as an example the pistons u and vas
shown provided with four wings, however the number of wings is not limited to
four. Figure 3 shows the piston u in detail, the other piston v is exactly like it,
and the individual wings of both pistons u and v pass in between each other as
shown at Figure 2. The wings of both pistons revolve close to the inner walls of
the drum or cylinder and are connected on the one side with a disc u² which
however may also be omitted. Both the pistons are by suitable gearing made to
Whilst the four
move during their revolution alternately faster and slower.
winged piston Figures and 3 moves quicker, the other four winged piston v
moves slower in the direction of the arrows (Figure 2). If for instance in this
case the drum serves as a water pump the water entering by four inlet ports ( in
the circumference of the drum Figures 1 and 2 which communicate with an
annular inlet passage d2 Figure 1. around the cylinder or drum d, flows in the
direction of the arrows into the four smaller sector shaped intermediate spaces
between the wings whilst the water which had previously been sucked into the
other four sector shaped spaces II, the contents of which during the quicker
revolving of the wings of one piston are now reduced, will be forced out through
other similar outlet ports O Figures 1 and 2 into another annular passage d' next
to the first named annular passage. These annular passages and d² are provided
with pipes d³ and d Figure 1 for the suction and delivery. When the wings of
the one piston comes up to those of the other piston u the latter begin to move
quicker, whilst the first piston v lags behind, the previously filled spaces I empty
themselves and the emptied spaces II are again filled. During this however both
pistons always move so far forward that the following inlet or outlet ports o o¹ let
the water in or out for the spaces (I and II) required. These openings o o¹ are, as
shown in Figure 1 set somewhat out of a line with each other. The described
alternately quicker and slower movement of the pistons during their revolution

page_text: produces a continual suction and delivery of the water by a continuous revolution
of the driving axle or shaft a². This shaft revolves in the bearings or standards a
and each end of the shaft may be provided with a pulley a' by means of which
motion is communicated to the aforesaid shaft a².
From this continued revolution of the shaft a the described periodical slower
and quicker revolving motion of the winged pistons and v is attained by means
of gearing on each side of the cylinder d (or it may be only on one side). In
Figure 1 the internally toothed wheels b are situated on the shaft a² which wheels
each gear with a pinion 6' which is movably fixed on the crank pin of a crank b²
which is fastened to the piston shaft a² and connected by means of a crank c or
eccentric on the same crank pin and by a connecting rod c¹ from the said crank or
eccentric to a crank c² which as shown in Figure 3 is secured to the hollow nave
or boss u¹ or v¹ of a rotating winged piston u and v. The toothed pinion 61 on the.
left side is in its highest position, Figure 6 when the corresponding tooth pinion b¹,
on the right of the drum, Figure 7 is in its lowest position. When the crank b²
Figure 6 is moved in the direction of the arrow to the right, the axle of the tooth
pinion b¹ fixed on to the crank b² (while the pinion b¹ rolls along and gears into
the teeth of the internally toothed cog wheel b) goes as shown by the arrows; to
the left. Every point of the pitch-line of the pinion 6' therefore describes a hypo-
cycloid and the pin i of the crank c moving therewith makes a similar curve as
shown in dotted lines x, x1, x2, 3. The connecting rod c¹ thereby swings on pin at
the outer end of the crank c² on piston nave and as now the movement of the
crank pin tallies tolerably with the swing curve of the connecting rod c¹ it will
be seen easily, that during the first periods of the movement of pinion 61 and
crank c of the same the revolution of communicated from the crank 62 to the other
crank c² by means of crank c and rod c¹ is retarded. If, on the other hand, the
crank c is in the opposite position shown at Figure 7, by further turning of the
crank 62, the crank c² on the piston nave will turn quicker and it follows that
during one half of the revolution of the pinion 61 by the crank c a retardation
takes place and during the other half an acceleration of the crank c² The amount
of the retardation or acceleration alters at every point, so that the before described,
periodical different movement of both pistons takes place. The accelerating or
retarding motion of the one piston towards the other takes place four times during
one revolution of the driving shaft a². Whilst the progressive crank pin i is in the
first half of the Cycloidic path x, x1, x2, x³, the piston u remains behind while the
other piston moves on ahead. And on the contrary whilst the crank pin i is on
the second balf of the cycloidic path the piston u goes on ahead and the piston v
remains behind.
From the foregoing it will be seen without further explanation, why the crank c
Figure 7 must move in an altered direction for the turning of the piston v, to the
inside teeth of the fixed toothed wheel b, so that it (the crank c) is in the middle
parts of the path 2 Figure 7, when the crank c serving to turn the piston u stands
at the beginning of the path x Figure 6.
The diameter of the pitch line of the toothed wheels b¹ is exactly the same as the
fourth part of the diameter of the pitch line of the toothed portion of the fixed
wheel b so that by once turning the crank 62 the accompanying crank pin i exactly
describes four cycloidic bows x, x², x², x³.
The toothed wheel mechanism can be modified for driving the multiple winged
piston u and vin several ways. In the arrangement shown in Figures 4, 5 and 8
the driving axle or shaft a² running continuously and turned by the pulley a¹ fixed
thereto in the standards a turns the tooth wheel 1, Figure 5 and this sets the tooth
pinions 2.(half the size of the preceding and turning in standards a³) into a velocity
double as great as that of the star wheel 2. On the axle of the pinion 2 there is
fixed a tooth wheel 3 of double the diameter of the pinion which wheel (3) com-
municates motion to tooth wheels 4 and 5 of like diameter which are mounted on
a common boss n and are revolved round the driving axle a² at double as many
revolutions. as .the wheel 3 which drives them, and therefore the wheels: 4 and 8

page_text: revolve at four times the rate in the same direction as shown by the arrows in
Figure 5 as the first named wheel 1.
Naturally the transmitting gearing of the wheels may be varied as long as the
wheel 5 has the described proportionate speed to shaft a².
By means of the double armed lever w turning in the direction of the arrow
with shaft a² see Figures 4 and 8 the two tooth wheels b and b¹ having their axes
turning in the ends of the lever ware caused to turn in the same direction
But
at the same time the wheels b and bare turned round their axes in the direction of
the arrows Figure 8 by reason of their gearing with the wheel 5 which turns in
the same direction but four times quicker. The diameter of the latter wheel is to
that of the two equal sized wheels b and b¹ as four to three so that when the
lever with the wheels b and b¹ makes a quarter of a turn then the pin i of the
crank con the spindle of the wheel b¹ will describe the path x and the pin i¹ of
the crank e on the spindle of the wheel b will describe the path y in the direction
of the arrows
As the pin i is at the beginning of its path when the pin is about
half way of its path the already described operation of the arms c² and e² connected
by rods c¹ and e¹ to i or i¹ namely a periodically quicker and slower turning of the
same is here again repeated. The arm c² is as shown in Figure 4 on the hollow
nave u¹ of one piston u (not shown) and the arm e² is on the spindle at which can
turn in the nave of the lever w; on the spindle a is also fixed the piston v (not
shown) by means of its nave v¹. In accordance with the arms c² and e² the pistons
connected therewith will also turn so that simultaneously at four different points
of the circumference of the casing d a suction and a delivery of water or other
fluid (air gases &°) will take place as in the previously described case.
Instead of four wings to each piston any other number of wings may be used
without altering the nature of the invention, only the relative diameters of the
wheels and the length of levers or cranks will have to be varied accordingly.
The apparatus may also instead of working as a pump, act as a motor, by letting
compressed air or other fluid under pressure enter the annular passage for the
pressure side and without using any slide or other valves. As the oscillating
motions of both pistons are quite similar, one piston may be worked from the
working mechanism of the others as long as the phases of the motions change
properly.
For
Figures 9 to 12 represent such a modification; as shown at Figures 9 and 10
a lever e¹ is fixed on the engine shaft a² and carries a pinion b¹ which can turn
freely on a fulcrum pin and rolls on the outside of a tooth wheel b (like the so-called
sun and planet motion). The tooth wheel is fixed on the shaft bearing a.
a four winged piston the pinion is one fourth of the diameter of the wheel.. Each
part of the pitch line of the pinion describes four epicycloids with the circumference
of the wheel as basis. A short crank u is fixed on the pinion fulcrum and its
crank pin likewise describes four such epicycloids. A connecting rods from the
crank pin to a block t which works in guides n on the lever e¹ causes the block to
work four times inwards and four times outwards for each revolution of the lever et
To each side of the block t is jointed a link e² and f2 which links are jointed each
to a lever e³ and f³ the latter oscillate round the shaft a² whereby the shafts a*
and u¹ upon which the levers e³ and f³ Figure 9 are fastened likewise oscillate
whilst they at the same time rotate continuously upon a circle with the said
lever e¹ The shaft u¹ however carries a piston u and the shaft u¹ carries a piston v
which pistons oscillate four times to and fro at the rotation of lever e¹ in con-
sequence of the described motions of the levers e³ and ƒ³ so that the liquid is
drawn in and forced out at 4 different points of the circumference of the drum.
Or again according to a modification shown in Figures 11 and 12 a lever e¹ is
also fixed on the shaft a² which is driven by a strap pulley a¹. The lever carries
a pinion b which as before rolls round a four times larger tooth wheel fixed to the
bearing a of the shaft and describes four epicycloids and so also a crank c on the
pinions fulcrum. pin. A. connecting rod c¹ from the crank pin transmits oscillating
motion to a triangular piece e which turns on a fulcrum pin o on the lever e¹ and

page_text: from one pin o transmits oscillating motion to a crank or lever on the shaft a¹ of
one of the pistons, and from another pin o' transmits motion by a link e' to a lever
or crank e³ on the nave sleeve of the other piston so that these two cranks swing
against and from each other and the pistons accordingly also.
Instead of pistons with four wings I may of course employ more than four.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is
:-
First In rotary piston pumps, meters, and motors the application of two
multiple wing pistons u and v each on a separate shaft, in such manner that the
pistons by one turn of the driving shaft obtain a more than twofold change from
quick to slow or vice versa at certain points of the circumference of the casing, for
instance by tooth wheels b 61 rolling on each other, for the purpose of enabling the
casing to draw in or force out fluids by the narrowing or widening of the spaces
between the wings.
Second-The mechanism described with reference to Figures 1 to 3 and 6 to 7
for driving the pistons u and v viz the fixed inside or outside tooth wheels b and
the cranks 62 fixed on the driving shaft a² and having smaller tooth wheels b¹
which roll around the wheels b and are provided with cranks or eccentrics c which
by rods c are connected to cranks c² fixed on the naves bosses u¹ and v¹ of the
pistons for the purpose of accomplishing the aforesaid firstly claimed periodical
unequal turning of the two pistons while the driving shaft a² revolves con-
tinuously.
Third: The modification for driving the pistons u and v described with
reference to Figures 4. 5 and 8 viz the wheel gearing 1, 2, 3, 4 worked from the
driving shaft a for driving the tooth wheel 5 also the double armed lever w fixed
on the shaft a2 and provided with tooth wheels b¹ and b gearing with the wheel 5
and having cranks or eccentrics c and e which by rods c¹ and e¹ move the levers c²
and e2 to which respectively the shaft a¹ with nave v₁ of the piston or the hollow
nave u¹ of the piston u are fixed.
Fourth-The modification described with reference to Figures 9 and 10 for
working the arms e³ and f³ viz the crank u connecting rod 5 sliding piece t and
rods e² and f² whereby the shaft u¹ for the wing piston u and the shaft at for the
wing piston vare turned forward alternately periodically quicker,
Fifth The modification described with reference to Figures 11 and 12 for
moving the pistons u and v viz the crank c and rod c¹ for oscillating the triangular
piece e which by means of the rod e² turns the lever es on the hollow shaft u¹ of
one piston u periodically quicker forward and by means of the pin o² turns the
lever fs on the shaft at of the other piston vin a similar manner.
Dated this Twenty first day of January 1885