IMPROVEMENTS IN ROTARY ENGINES
Year: 1883

page_text: LETTERS PATENT to Thorsten Nordenfelt of 53 Parliament Street in the
City of Westminster for an Invention of "IMPROVEMENTS IN ROTARY
ENGINES the result partly of a communication made to him from abroad by
George William Garrett of Stockholm in the Kingdom of Sweden and partly
"
PROVISIONAL SPECIFICATION left by the said Thorsten Nordenfelt at the
Office of the Commissioners of Patents on the 7th June 1883.
"
THORSTEN NORDENFELT of 53 Parliament Street in the City of Westminster
"IMPROVEMENTS IN ROTARY ENGINES [the result partly of a communication
made to him from abroad by George William Garrett of Stockholm in the Kingdom
of Sweden and partly of invention and discovery made by himself]
This Invention has for its object improvements in rotary engines and relates to
an improved design of rotary engine for making use of the power of steam air
gases or other fluids under pressure more economically and in cheaper machines
than has heretofore been done.
In general the motor consists of a cylindrical drum which when acted on by
pressure revolves eccentrically within a cylinder. The drum is so attached to an
axle which passes through the centre of the cylinder that when the drum revolves
the axle must also revolve. The ratio of the diameter of the drum to the diameter
of the cylinder is about as 4 to 5. The inlet stream is separated from the exhaust
by means of a plate moving radially in a sheath attached to the cylinder so as
always to remain in contact with the revolving drum. The motion of this divider
is controlled preferably by the motion of the revolving drum in a duplicate
machine. The breadth of the divider at the top where the drum comes into
contact with it should bear a definite proportion to the eccentricity of the drum
and with the proportions above given should be about one half of the radius of the
cylinder. The stroke of the divider is equal to the diameter of the circle described
by the centre of the drum. The drum sits radially loose upon the axle so that
the centrifugal force generated by its speed of revolution acts to ensure close
contact between the drum and the cylinder

page_text: The pressure between the surfaces is controlled by approximately balancing the
drum about the axle.
A complete motor may consist of four drums revolving in four cylinders arranged
in two pairs. In each pair the drums are similarly situated on the axle as regards
the position of their centres but the eccentricity of one pair of drums is
diametrically opposed to the eccentricity of the other pair of drums so that the
motion given to one divider by its respective drums may control the motion of the
other divider so that at all times the dividers shall remain in contact with their
respective drums. This is the design more especially denoted by the term
Nordenfelt compound rotary motor and may be more particularly described as
follows:-
The motor consists of two parts which are alike except in the position of the
centres of the revolving drums which are situated on opposite sides of the axle.
The reason for this arrangement of the two drums is that one drum whilst
descending forces its divider down which being connected by a reversing lever
with the other divider forces the latter up and keeps it in contact with its
respective drum. The bearings of the lever are adjustable in order to set the
divider up to the drum. The dividers therefore have their motions from the
revolving drums and are in no way dependent on the axle which is an advantage.
No spring is used in connection with the dividers by which means much friction
between the divider and the drum is avoided and they are held in continual
contact.
Each of the two parts of the motor consists of:-Two cylinders which for
convenience may be cast in one piece but be separated by a wall which is cut so as
to allow one divider to rest upon the two revolving drums which as before stated
are placed radially loose upon the axle which passes through the centre of the
cylinders. An advantage of this is that as the cylinders or drums or both may be
worn the drum can move out radially in the direction of its eccentricity and so
always remain in contact with the cylinder.
Of the two cylinders the one is the high pressure and the other the low pressure.
The low pressure cylinder is say 10 times as long and its contents 10 times that
of the high pressure cylinder and the areas on which the steam acts are in the
same proportion.
Passages with valves which are stationary when the engine is at work admit
steam on one or other side of the divider as required.
The pressure on the drum causes it to revolve and the revolution being completed
the steam from the high pressure cylinder is allowed to expand into the low
pressure cylinder whence it escapes either into the air or into a condensor. The
centres of the revolving drums in the high and low pressure cylinders have the
same position as regards the centre of the cylinder.

page_text: square in section in such manner as admits of the drums moving upon the axis
radially. The centres of the revolving drums in the high and low pressure
cylinders have the same position as regards the centre of the cylinder.
e¹. e. are moveable partitions or dividers they are enclosed in spaces provided for
them between the castings a. a. The breadth of the divider at the top where the
drum comes into contact with it should bear a definite proportion to the eccentricity
of the drum and with the proportions shown should be about one half of the radius
of the cylinder. The stroke of the divider is equal to the diameter of the circle
described by the centre of the drum. The divider e¹ is supported by a rod fl
from the rocking lever g¹ and similarly the divider e³ is supported by the rod f
from the rocking lever g². These parts are so adjusted that whilst the axis c
rotates and the drums with it the motion given to one divider by its drum controls
the motion of the other divider so that at all times the dividers are actuated by
two drums and remain in contact with their respective drums; one drum whilst
descending forces its divider down which being connected by a reversing lever
with the other divider forces the latter up and keeps it in contact. The parts are
adjustable in order to set the divider up to the drum. The dividers therefore have
their motions from the revolving drums and are independent of the exact position
of the axle which is an advantage. No spring is used in connection with the
dividers by which means much friction between the dividers and the drums is
avoided and they are held in continual contact.
Passages with valves which are stationary when the engine is at work admit
steam on one or other side of the divider as required.
h. i. k. and and h¹. . . and are these valves which are provided for the
purpose of reversing the engine. In the case of a motor running always in the
same direction the valves are not required. m is the inlet pipe by which the
steam or other fluid to work the engine is admitted is the exit pipe. When the
valves are set as indicated in the drawing the steam or fluid entering at m finding
the valve open passes by a channel formed in the divider e¹ into the part of the
cylindrical space around the drum d. This is the smaller of the two drums and
that against which the steam or fluid at the full pressure at which it is admitted
at m operates. The steam or fluid is unable to pass the lines of contact of the
drum with the wall of the cylinder and with the divider and efficient packing is
also provided as the drawing indicates at x. x. x. to prevent its finding its way past
the ends of the drum and the divider. Hence the steam can only pass forward by
compelling the drum and axis to rotate. When in this way the steam or fluid
passes to the other side of the divider it finds the valve ¹ open and enters the
pipe o. The pipe o is connected by a pipe o which may be of large capacity and
be steam jacketted as may be also the cylinder or either of them; the pipe o'
passes over the top of the cylinder to the pipe o¹ and leads the steam or fluid over
to the opposite side of the low pressure cylinder which it enters by the open
valve k. The steam or fluid now expands into the larger space provided for it
operating against the larger drum d' as previously against the smaller drum d¹.
Finally the steam or fluid escapes by the open valve into the exit pipe n and
into the atmosphere or into a condenser.
An air pump and cold water pump may be connected with the motor by suitable
machinery so that the motor may act as a complete high pressure expansive and
condensing engine.
•
The revolving drums as before stated are placed radially loose upon the axle
which passes through the centre of the cylinders and centrifugal action regulates
the contact between drum and cylinder. An advantage of mounting the drum
loosely on the axis is that as the cylinders or drums or both may become worn the
drum can move out radially in the direction of its eccentricity and so always
remain in contact with the cylinder.
The weight of the drum is so distributed as to give any degree of preponderance
on either side of the axis as may be required, but by preference I make the drum,
to preponderate slightly on the sideaway from the cylinder-I then have

page_text: studs c*. c*. fixed in the axis and so adjusted in length as to allow just a clearance
between their ends and the interior of the drums when this is in contact with the
cylinder.
I arrange coiled springs also around these studs to press the drum up to the
cylinder but this pressure is regulated by the centrifugal action and become less
effective as the speed increases. The adjustment may be such that at high speeds
the drum recedes into contact with the studs cx and then there will be no friction
between the drum and the cylinder.
For reversing the direction of rotation the valves are all shifted simultaneously
by means of the sliding bars p. p. which receive an endwise movement from a hand
lever. The bars are slotted and small rollers upon the valve rods are received into
the inclined slots. It will be observed that when the valves h. . k and are open
as described above the other valves h¹. i. k. and are closed. To change the
direction of rotation of the motor the position of all the valves is reversed.
In a single machine or motor one end of the reversing lever is acted upon by the
drum of the motor and the other end by an eccentric exactly like a portion of the
drum but fixed on the opposite side of the axle beyond the cylinder of the motor.
Having thus described the nature of the said invention and the manner of
performing the same I would have it understood that I claim :-
First A compound rotary motor substantially as described.
Second-The combination in a rotary engine substantially as described of a
cylinder an eccentric drum capable of radial motion on the axle and a divider
worked by the eccentric drum and a similar eccentric.
Third The combination in a rotary engine substantially as described of two
cylinders two eccentric drums diametrically opposite on the same axis and two
dividers the said dividers being coupled so that one controls the other substantially
as described.
Fourth The combination of cylinder eccentric drum and divider forming a
rotary engine in which the drum is loose on the axis and free to be moved by
centrifugal action which thereby regulates the contact with the walls of the
cylinder substantially as described.
Fifth The combination substantially as described of a cylinder divided into two
compartments high and low pressure two eccentric drums and dividers, the wholo
composing a compound rotary engine.
Sixth-The combination substantially as described of a pair of such compound
rotary motors constituting the Nordenfelt compound rotary motor.
In witness whereof I the said Thorsten Nordenfelt have hereunto set my hand
and seal this fourth day of December in the year of our Lord One thousand eight
hundred and eighty three.
MHN