IMPROVEMENTS IN FLUID PRESSURE
Year: 1883

page_text: LETTERS PATENT to Henry Coppinger of Tivoli, Cork, in the County of
Cork, Ireland, for an Invention of IMPROVEMENTS IN FLUID PRESSURE
PROVISIONAL SPECIFICATION left by the said Henry Coppinger at the
Office of the Commissioners of Patents on the 31st October 1883.
"IMPROVE-
HENRY COPPINGER of Tivoli, Cork, in the County of Cork, Ireland,
MENTS IN FLUID PRESSURE ENGINES, APPLICABLE ALSO AS PUMPS OR METERS
"
My invention relates to rotary engines to be worked by pressure of fluid such
as steam, water, gas, or air, and which engines, instead of being employed as motors
can be used as pumps or fluid meters.
Within a cylinder fitted with cylinder covers each having a central stuffing box
or its equivalent I provide a rotatable part I call a piston; resembling in form
two half turns of a helical screw thread, the one half being a "half turn" of a
right hand thread, and the other a half turn of a left hand thread. Theso two half
turns or half discs are united at their radial edges in such a way as to form one
piece having a circular circumference surrounding an axis common to both halves.
Thus the piston may be described as a double helical plate having two undulating
surfaces and a continuous periphery. This double helical plate or piston is
mounted by means of a central boss on a central shaft which passes through the
stuffing boxes in the cylinder covers. The periphery of the said piston is turned
accurately to fit the cylinder and is fitted with metallic or other packing when
necessary. The right and left hand screw blade surfaces are "
got up" truly at
right angles with the axis of the shaft, and the surfaces of the piston, where tho
right and left hand screw blades meet, are faced (and packed when necessary) so
as to fit steam tight against the cylinder covers.
In a plane parallel to the axis of the shaft are formed two apertures in the
cylinder covers extending from the trued surface of the boss of the piston to the
circumference of the cylinder. These apertures are provided with suitablo
external casings or jackets in which slide-abutments work to and fro passing fluid
tight through the apertures in the cylinder covers fitting accurately between the

page_text: circumference of the cylinder and the piston boss, and forming a fluid tight joint
with the piston surfaces by being kept continuously pressed against thom
The slido-abutments pass the one through the one cylinder cover, and the other
through the other cylinder cover on opposito sides of the piston, and are so arranged
that when the one advances the other retires, their ends maintaining perfect
contact with the respective faces of the piston
Fluid ports are provided in the cylinder covers close to the slides in corresponding
positions and the exhaust ports are provided in corresponding positions on
the other sides of the slides, these ports becoming either exhaust or admission
ports according to which way the engine may be running.
Engines having helical surfaces such as I have above referred to operating
in conjunction with sliding abutments according to my invention may be con-
structed in various forms. Thus, for example, the piston may be much thickened
and may have correspondingly curved surfaces at either end, or may be curved
only at one end, one slide only being thon used; or the cylinder covers may be
curved and the slides be placed in a rovolving cylindrical block arranged in the
cylinder so that the slides shall form the piston or pistons.
The pitch of the screw blades may be altered near where they meet, so that the
motion of the slides need not be abruptly reversed. The slides, also, may be
joined through an aperture in the side of the cylinder, thus forming one piece.
The engine is so arranged that at no time shall steam or fluid pass through it
without turning the piston. This may be effected in the above described arrange-
ment by making each of the faces where the right and left hand screw blades
meet large enough to close steam and exhaust ports at the instant of its passing
them; but any other suitable arrangement for the purposo may be employed.
The slide edges prossing against the piston are so arranged as to provide more
than a mere line of contact

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Henry Coppinger in the Patent Office on the 26th April 1884.
HENRY COPPINGER, of Tivoli, Cork in the County of Cork, Ireland, IMPROVE-
MENTS IN FLUID PRESSURE ENGINES APPLICABLE ALSO AS PUMPS OR METERS.
My invention relates to rotary engines to be worked by pressure of fluid such as
steam water gas or air and which engines instead of being employed as motors can
be used as pumps or fluid meters.
Within a cylinder fitted with cylinder covers each having a central stuffing box
or its equivalent I provide a rotatable part I call a piston resembling in form two
half turns of a helical screw thread the one half being a "half turn" of a right
hand thread and the other a half turn of a left hand thread. Those two half
turns or half discs are united at their radial edgos in such a way as to form one
piece having a circular circumference surrounding an axis common to both halves,
Thus the piston may be described as a double helical plate having two undulating
surfaces and a continuous periphery. This double helical. plate or piston is
mounted by means of a central boss on a central shaft which passes through the
stuffing boxes in the cylinder covers-The periphery of the said piston is turned
accurately to fit the cylinder and is fitted with metallic or other packing when
necessary. The right and left hand screw blade side surfaces are "got up" truly
and by preferance at right angles with the axis of the shaft and the surfaces of the
piston where the right and left hand screw blades meet are faced (and packed
when necessary) so as to fit steam tight against the cylinder covers and pass over.
the slide apertures mentioned below steam tight and without obstruction.
:
In a plane parallel to the axis of the shaft are formed two apertures in the
cylinder covers extending from the trued surface of the boss of the piston to the
circumference of the cylinder. These apertures are provided with suitable external
casings or jackets in which slide-abutments work to and fro passing fluid tight
through the apertures in the cylinder covers fitting accurately between the
circumference of the cylinder and the piston boss and forming a fluid tight joint
with the piston surfaces by being continuously pressed against them.
The slide-abutments pass the one through the one cylinder cover and the other
through the other cylinder cover on opposite sides of the piston and are so arranged.
or connected that when the one advances the other retires their ends maintaining
perfect contact with the respective faces of the piston.
:
Fluid ports are provided in the cylinder covers close to the slides in corresponding
positions and the exhaust ports are provided in corresponding positions on the:
other sides of the slides these ports becoming either exhaust or admission ports
according to which way the engine may be running.
Engines having helical surfaces such as I have above referred to operating in
conjunction with sliding abutments according to my invention may be constructed
in various forms. Thus for example the piston may be much thickened and may
have corresponding curved surfaces at either end as above oxplained or may bo
curved only at one end one slide only being then used: or the cylinder covers may.
be curved and the slides be placed in a revolving cylindrical block arranged in tho -
cylinder so that the slides shall form the piston or pistons.
The pitch of the screw blades may be altered near where they meet so that the
motion of the slides need not be abruptly reversed-The slides also may be joined
through an aperture or channel in the side of the cylinder thus forming one piece. :
The engine is so arranged that at no time shall the steam or fluid pass through
it without turning the piston. This may be effected in any suitable way such
88

page_text: (in the above described arrangement) by making each of the faces where the right
and left hand screw blades meet large enough to close steam and exhaust ports at
the instant of its passing them.
The slide edges pressing against the piston are so arranged as to provide for
more than a mere line of contact.
To enable my invention to be fully understood and readily carried into practice
I proceed to describe a construction of engine according thereto by reference to the
accompanying drawings whereof Fig 1 is a part section of the engine in a plane
passing through the axes of the rotating piston shaft and of the rods actuating the
abutment slidos.
Fig 2 is an end view of the engine showing in section one of the abutment slido
jackets on the lino . y. of Fig. 1. A is a short working cylinder in which revolves
the right and left handed helical piston B carried by the central boss B' mounted'
on and keyed to the driving shaft B which is carried in suitable steam tight
bearings (or stuffing boxes) as shown. At the radial junctions of their curved sides
the pistons are turned truly so as to form steam tight joints with the cylinder
covers the width of these surfaces being sufficient to just cover the steam and
exhaust ports F. F. as the said surfaces pass over these ports. as shown by the
dotted lines o. c* in Fig 2. C. O' are the cylinder covers D. D¹ the slide-
abutments working in their respective jackets E E' and steam tight through the
cylinder covers C. C' against the cylinder A and against the boss B¹ and the curved
faces of the piston B.
The action of tho engine is as follows:-When actuating fluid which I will
assume to be steam is admitted through the port F (Fig 2) it will press against the
abutment-slide D¹ and against the oblique right hand surface of the piston Fig 1.
causing it to rotate in the direction of the arrow until half a revolution has been
made when the exhaust steam from this side of the piston has escaped through the
exhaust port F' (Fig 2) the left hand side of the piston (Fig 1) will have its surface
acted upon by the full force of the steam which will have been admitted by the
left hand steam port immediately opposite the port F in the left hand cylinder
cover.
The slide abutments are by suitable means such as the rods d. d kept close up
to the piston surfaces and caused to advance or recede as required so as to form
steam tight abutments. From this it will be understood that the steam acts on
both sides of the piston and that when it has ceased to act on the one side it will
be acting with its fullest effect upon the other side and so on alternately permitting
no dead point in the working of the engine. I also propose to introduce rings on
each side of the central boss, or some other suitable thrust bearings (not shown
in the drawing) for the purpose of preventing end play in the piston.
It will be evident that if the shaft carrying the piston be rotated by some force
applied externally of the cylinder the engine can be used as a pump also that if
non-elastic fluids be caused to pass through the cylinder so as to rotate the piston
and the shaft be made to actuate suitable registering mechanism the apparatus will
serve as a meter.
Having described the nature of my said invention and in what manner it is to
be carried into practical effect I hereby declare that what I claim as secured to
me under the Letters Patent first hereinabove in part recited is:-
1. The improved fluid pressure rotary engine constructed arranged and operating
substantially as hereinabove described with reference to the drawings.
2. The use as a pump of apparatus constructed arranged and operating substantially
as hereinabove described with reference to the drawings.
3. The use as a meter of apparatus constructed arranged and operating substantially
as heroinabove described with reference to the drawings.
4. In a rotary apparatus applicable as a motor or pump or meter as hereinbefore
set forth the construction with a sliding abutment or abutments in a cylinder of a
rotatable part resembling in form two half turns of a helical screw thread
respectively right handed and left handed united at thoir radial edges in such a

page_text: way as to form one piece having a circular circumference surrounding an axis
common to both halves as and for the purpose specified.
5. As a modification of the arrangement referred to in claim 4 the use in
combination of slides in a cylindrical block able to rotato in a cylinder provided
with ends curved and for the purposes specified such curved ends corresponding to
the curved portions of the rotary piston in the arrangement mentioned in claim 4.
In witness whereof I the said Henry Coppinger have hereunto set my hand and
seal this twenty fourth day of April in the year of Our Lord One thousand eight
hundred and eighty-four.
HENRY COPPINGER (L.S.)