IMPROVEMENTS IN ROTARY ENGINES
Year: 1881

page_text: LETTERS PATENT to Antoine Brossard, of Paris, in the Republic of France,
temporarily of Swansea, in the County of Glamorgan, for an Invention of
IMPROVEMENTS IN ROTARY ENGINES,"
"
PROVISIONAL SPECIFICATION left by the said Antoine Brossard at the
Office of the Commissioners of Patents on the 25th November 1881.
ANTOINE BROSSARD, of Paris, in the Republic of France, temporarily of Swansea,
in the County of Glamorgan. "IMPROVEMENTS IN ROTARY ENGINES."
These improvements consists, firstly, in a novel construction of piston, whereby
the dead point may be overcome; and, secondly, in a novel arrangement of cut off,
and in the means for working the same.
The engine consists of a cylinder provided with a central shaft, which is carried
in bearings in the cylinder ends. The cylinder is provided with the usual inlet
and outlet ports and a cylindrical valve, which is contained in a suitable valve box
arranged on the top of the cylinder.
The piston consists of a flap or plate the entire length of the cylinder and
mounted on the central shaft, and of a ring or small cylinder of corresponding
length placed outside the shaft and flap, and provided with a pin or projection at
either end, which takes into a circular groove formed excentrically of the shaft in
the cylinder ends. A portion of this ring or cylinder is cut away, so that the flap
or plate may project through it. In one of the cylinder ends passages are made,
which connect with the spaces between the opposite sides of the flap and the
interior of the ring or small cylinder.
In working the engine the steam or other fluid first enters this space and acts
on one side of the flap, driving it past the dead point and uncovering the inlet
port of the main cylinder. The steam in full force is then admitted to the main
cylinder, and acts on the flap as it becomes gradually projected through the
opening in the ring, and forces it forward. At a certain noinent the inlet port is
closed, and the steam then works expansively until the outlet is opened.
On the main shaft is keyed a mitre wheel, which gears with a similar wheel on

page_text: the spindle of the ball governor, which thus receives its motion from the main
shaft. Keyed on the spindle is an excentric, the strap of which is connected with
a vertical rocking bar. Sliding on this bar is a collar, to which is attached one
end of a connecting rod. The other end of this rod is adjustably connected with a
pendent rocking arm, which is attached to a sliding rod placed centrally of the
valve. The connecting rod is pivotted to a link in connection with the collar of
the ball governor.
On the sliding rod are mounted two pistons, between which the steam passes.
The distance between these pistons may be regulated in any convenient manner.
The amount of traverse given to the sliding rod is regulated by the rising or
lowering of the connecting rod by the balls, so that the longer the stroke the
groater will be the length of time during which steam is cut off from the cylinder,
and the speed of the engine will thereby be correspondingly reduced.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Antoine Brossard in the Great Seal Patent Office on the 25th May
1882.
ANTOINE BROSSARD, of Paris, in the Republic of France, temporarily of Swansea,
in the County of Glamorgan. "IMPROVEMENTS IN ROTARY ENGINES."
These improvements consist, firstly, in a novel construction of piston, whereby
the dead point may be overcome; and, secondly, in a novel arrangement of cut off,
and in the means for working the same.
In the accompanying Drawing Fig. 1 is a longitudinal sectional elevation of my
improved rotary engine, Fig. 2 is a plan view of the saune, Fig. 3 is an end
elevation showing the governor, and Fig. 4 is a cross section on the line x, x, of
Fig. 1.
A is a cylinder; B, B₁, are the cylinder ends, in which are formed the bearings
for a central shaft C; D is a valve chest or box containing a steam valve D', and
with which the steam inlet and outlet pipes E, F, are connected.
'
The piston consists of a blade or palette G suitably mounted on or secured to
the shaft C, and a small cylinder H enclosing the shaft C and the blade G. A
longitudinal slit or opening is formed in the cylinder H, through which the blade G
projects. The outer edges of the blade G and the edges of the cylinder on either
side of the opening or slit are provided with suitable packing to render the parts
steam tight.
'At either end of the cylinder H is a projection a, which works in a groove
formed excentric to the central shaft C in the cylinder ends B, B¹.
b
In the end B of the cylinder A are two passages (shown in dotted lines in
Fig. 1), which are in connection with annular spaces c, d, formed in the cylinder
end. Opening into these spaces are passages e, f, bored in the central shaft C

page_text: parallel with the axis, and which communicate by means of lateral passages, shewn
dotted in Figures 1 and 4, with the interior of the cylinder H on opposite sides of
the blade G. Each of these passages is used as either an inlet or outlet passage,
according to the direction of travel of the engine. The passages in the cylinder
end B are connected with a valve chest I by the pipes J, K. The valve chest I
contains a plug valve or cock L, in which passages are so formed that the steam
pipe E and the exhaust F may be brought into connection with either of the
pipes J, K, as required.
Suppose it is desired to drive the engine in the direction indicated by the arrow,
Fig. 4, the piston being shewn at the midway point in that Figure, steam is
admitted by moving the valve L through one or other of the pipes J, K,
say J.
into the passage e, whence it passes by the port e¹ into the space A in rear of the
blado G. The interior of the cylinder H acts as the abutment, and the blade is
moved forward beyond the inlet g' of the main cylinder by the pressure of
steam in M.
'
As the blade G moves, rotary motion is communicated to the cylinder H, and
the external periphery of the cylinder H coming in contact with the interior of
the main cylinder A makes with it a steam tight joint between the inlet and
exhaust ports, which are for the time being open.
As the rotary motion continues the blade G will be gradually projected through
the cylinder A, the position of the cylinder H in the main cylinder always
remaining the saine, and the main steam therefore will act upon a gradually
increasing surface until the blade Ģ has arrived at half stroke, when the surface
will commence to diminish.
The entrance and exit of steam to the cylinder H is continuous so long as the
engines is working, and there is consequently always the samo surface area of the
blade G being acted upon. The working of the piston will be clearly understood
from the diagram, Figures 5, 6, and 7, which shew the position of the piston at
quarter, hall, and three quarter-stroke respectively.
The steain may be cut off from the main cylinder at any portion of the stroke,
the engine working expansively for the remainder of the stroke.
The steam in the cylinder H in front of the blade G will exhaust continuously,
say through the port f into the passage f, and it will pass thence through one of
the passages in the cylinder end B₁ into the pipe K, and through the valve L to
the exhaust F.
It will be unnecessary to further describe the valve L, as any one acquainted
with the construction of steain valves will be able readily to devise such a valve,
it being always understood that when the pipe J is admitting steain K is exhausting,
and vice verad.
The inlet and exhaust passages N, O, for the main cylinder A may be cast with
the cylinder.
The steam valve D' is placed horizontally above the cylinder A, and consists of
a hollow plug or cylinder D', in and round the periphery of which suitable ports
and passages are formed. The ends of the hollow plug or cylinder are closed in
any convenient manner, and the plug contains a pair of pistons h, h, mounted on
a rod i supported by the ends of the plug D', and capable of receiving a recipro-
cating movement, as will be hereafter describo. The steam before entering the
inlet passages passes between these pistons h, h, which are capable of being set at
any distance apart on the piston rod i by means of the right and left handed
thrends with which the rod i is provided, and thus the amount of steam entering
may be varied according to requirements by turning the rod in one direction or
the other.
The plug or cylinder D is oscillated to open or close the steam inlet by means
of a bevil pinion j, which takes into teeth formed on one end of the plug or
cylinder. Keyed on the axlo of the pinion j is a crank arm j', which is connected
by a link rod with a lever k. In like manner the valve L is provided with a
crank arm, which is also connected with the lever by a link rod j', as clearly
•

page_text: shewn in Fig. 2. By simply raising or lowering this lever from the position shewn
in Fig. 1 the valves may be opened in opposite directions, so that the engine may
be driven ahead or reversed as required. "P is a ball governor, the spindle of which
is driven direct from the shaft C through the bevil wheels 1, . Keyed on this
spindle is an excentric m, the strap of which is suitably connected to a vertical
rocking rod or barn, which has its fulcrum at n¹ on a bracket extending laterally
from the cylinder end B¹. Upon this rocking barn slides a sleeve o, to which are
pivotted a pair of rods p. The other ends of these rods p are secured to a rocking
arm g pendent from a bracket secured to the cylinder A. The lower end of this
pendent arm q is pivotted to one end of the piston rod i.
It will thus be seen that as the spindle of the governor rotates the excentric m
will rock the bar n, and this through the rods p will give a reciprocating movement
to the piston rod i and pistons h, h. By this means a regular cut off is obtained,
the pistons h, h, as the excentric rotates, alternately closing or contracting the inlet
opening.
To obtain a variable cut off the rods p are connected by the links with the
collar of the ball governor. As the balls extend the rods p are drawn up, and
with them the sleeve o on the rocking bar n. A longer stroke as the bar n rocks
is thereby given to the pistons, and the inlet opening is closed or contracted for a
longer time. As the speed of the engine slackens the sleeve o descends, and the
stroke of the pistons is correspondingly diminished, and the steam is allowed to
pass more or less continuously into the cylinder.
Having now described the nature of my Invention for "Improvements in
Rotary Engines," and explained the manner of carrying the same into effect, I
claim,―
First. Constructing pistons for rotary engines, substantially as and for the
purpose herein shewn and described.
Second. The arrangement of steam cut off valve and the means for working the
same, substantially as herein shewn and described.
Third. The construction and arrangement of rotary engine, substantially as herein
shewn and described.
In witness whereof, I, the said Antoine Brossard, have hereunto set my hand
and seal, the Twenty second day of May, in the year of our Lord One
thousand eight hundred and eighty two.