IMPROVEMENTS IN AIR COMPRESSORS AND APPARATUS FOR TUMPING OR FORCING FLUIDS.
Year: 1881

page_text: LETTERS PATENT to Herbert Fletcher, of Bolton-le-Moors, in the County of
Lancaster, Colliery Proprietor, for an Invention of IMPROVEMENTS IN AIR
"
LETTERS PATENT to Herbert Fletcher, of Bolton-le-Moors, in the County of
Lancaster, Colliery Proprietor, for an Invention of "IMPROVEMENTS IN AIR
COMPRESSORS AND APPARATUS FOR TUMPING OR FORCING FLUIDS.
PROVISIONAL SPECIFICATION left by the said Herbert Fletcher at the
Office of the Commissioners of Patents on the 21st May 1881.
HERBERT FLETCHER, of Bolton-le-Moors, in the County of Lancaster, Colliery
Proprietor. "IMPROVEMENTS IN AIR COMPRESSORS AND APPARATUS FOR PUMPING
OR FORCING FLUIDS."
My Invention relates to such apparatus employed in the exhausting, forcing, or
compressing of fluids as have valves which move with the pistons, and is particularly
applicable in cases wherein the pistons move at high rates of speed. In a form of
air compressor to which I have applied my Invention the inlet valve is carried by
the compressing piston, and as a consequence the said valve moves to and fro with
such piston, thus acquiring a momentum, due to its weight and velocity, which
tends to close it before the completion of the out stroke of the piston, thereby
causing a partial vacuum in the cylinder at the commencement of the in stroke.
The inertia of the valve also causes destructive shocks or haminering of the parts.
The object of my Invention is to obviate these defects, and for this purpose I
attach to each valve which is carried by the piston, or to several valves so carried,
a counterbalance weight, which also moves with the piston, but is so arranged as
that its inertia and acquired momentum shall neutralise the inertia and acquired
momentum of the valve. In an air compressor having horizontal cylinders, each of
the said valves is connected to one extremity of a lever, the fulcrum of which is
secured to the piston, or to a part which moves therewith, and the other extremity
of the said lever is provided with a weight, the said fulcrum being situated between
the said weight and the point of connection with the valve. The said weight is
made to be about equal in gravity to the valve and any parts which there may be
(Dmine Rd71

page_text: moving therewith, or the weight may be of less or of greater gravity than the
valve, the lever being suitably proportioned to enable the said weight to counter-
balance the valve. prefer to arrange for the weight to be adjustable by means of
a screw, so that by moving it nearer to or further from the fulcrum of the lever
the best results may be obtained. I have found that the employment of the said
counterbalance-weight in connection with the said valves, or with each valve,
enables me to run the "compressor" at a higher speed than could otherwise be
obtained without shock, noise, and loss from a partial vacuum. The arrangement
may be varied to suit the varying requirements of different cases, so long as the
counterbalance weights are employed to neutralise the momentum and inertia of
the valves.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Herbert Fletcher in the Great Seal Patent Office on the 19th
November 1881.
HERBERT FLETCHER, of Bolton-le-Moors, in the County of Lancaster, Colliery
Proprietor. "IMPROVEMENTS IN AIR COMPRESSORS AND APPARATUS FOR PUMPING
OR FORCING FLUIDS."
My Invention relates to such apparatus employed in the exhausting, forcing, or
compressing of fluids as have valves which move with the pistons, and is particularly
applicable in cases wherein the pistons move at high rates of speed. In a form of
air compressor to which I have applied my Invention the inlet valve is carried by
the compressing piston, and as a consequence the said valve moves to and fro with
such piston, thus acquiring a momentum, due to its weight and velocity, which
tends to close it before the completion of the outstroke of the piston, thereby
causing a partial vacuum in the cylinder at the commencement of the in stroke.
The inertia of the valve also causes destructive shocks or "hammering" of the parts
at its opening. The object of my Invention is to obviate, these defects, and for this
purpose I counterbalance the valve, or each valve, in such a manner as that the
inertia and momentum do not interfere with the right action of the valve.
In order that my Invention may be fully understood, I will refer to a Drawing
which I have attached hereto, and which represents a vertical section of the air
cylinder of an air compressor constructed on the principal of Sturgeon's Patent
trunk compressor. In the said Drawings a, a, are the two inlet valves, which are
mounted within the trunk pistons b, b, and c, c, are the ordinary outlet valves.
Each inlet valve is connected by means of a link d with one end of a lever e, which
is mounted upon a fulcrum f which is carried by the trunk piston. The other end
of the lever is provided with a weight g, which is adjustable upon the lever in
order that the momentum of the valve may be correctly balanced. The said weight
is made to be equal in gravity to the valve and any parts which there may be
moving therewith, or the weight may be of less or of greater gravity than the said
valve and moving parts, the lever e being suitably proportioned to enable the said
weight to counterbalance the valve. The dotted lines at l indicate a link which I
may use to connect together the two counterbalance-weight levers.
By the
employment of such a connecting link I can dispense with the use of the separate
weights g, g, the said links serving as a counterbalance for both valves, and I also
thus cause the inlet valve which is in compression to control the movement of the
inlet valve which is admitting fresh air. When the apparatus is at work the inertia
and acquired momentum of the counterbalance neutralise the inertia and acquired
momentum of the valve. I have found that the employment of the said counter-
balance enabes me to run the " compressor" at a higher speed than could
otherwise be obtained without shock, noise, and loss from a partial vacuum. The
arrangement may be varied, as by placing the counterbalance, or the link connecting
the levers and acting as the counterbalance, in any other position with regard to the
centre line of compressing piston, so long as the counterbalance is employed to
neutralise the momentum and inertia of the valves.
Having now fully set forth and indicated the nature of my said Invention, and
the manner in which the same may be carried into effect, I would state in conclusion
that what I claim is,―
Firstly. The employment of a balance weight and lever for counterbalancing the
piston carried valves of air compressors.
Secondly. The coupling together, whero two pistons are used to compress
alternately, the piston carried valves of one piston with the piston carried valves

page_text: of the other piston by levers and one or more connecting rods, so that the con-
necting rods counterbalance the valves to the desired extent.
In witness whereof, I, the said Herbert Fletcher, have hereunto set my hand
and seal, this Eighteenth day of November, One thousand eight hundred
and eighty-one.
Signed, sealed, and delivered
in the presence of
EDWARD K. DUTTON,
41, John Dalton St.,
Manchester
(Agent for the Patentee).
HERBERT FLETCHER. (L.S.)