IM- PROVEMENTS IN AND APPERTAINING TO MACHINERY OR APPARATUS FOR COM- PRESSING AMMONIACAL AND OTHER GASES, PARTS OF WHICH IMPROVEMENTS ARE ALSO APPLICABLE TO MACHINERY FOR COMPRESSING AIR, AND TO OTHER PURPOSES
Year: 1878

page_text: PROVISIONAL SPECIFICATION left by Edgar Gaylord Wheeler at the Office
of the Commissioners of Patents on the 5th April 1878.
EDGAR GAYLORD WHEELER, of the Strand, in the County of Middlesex. "IM-
PROVEMENTS IN AND APPERTAINING TO MACHINERY OR APPARATUS FOR COM-
PRESSING AMMONIACAL AND OTHER GASES, PARTS OF WHICH IMPROVEMENTS ARE
ALSO APPLICABLE TO MACHINERY FOR COMPRESSING AIR, AND TO OTHER
PURPOSES."
In engines used for compressing ammoniacal and other gases, it is of great
importance that the compressed gases should be as completely as possible expelled
from the compression cylinder at the end of each stroke of the piston. In order to
effect this it is necessary in the first place that the passages leading to and from the
valves should be so constructed as to contain as little as possible of undischarged
compressed gas when the valves are shut, and yet allow ample area for the passage
of the gases into or from the compression cylinder when the valves are open.
In carrying out my Invention, in order to effect this object I construct the inlet
and delivery valves with flat faces resting on flat seatings, and I fill up the opening
through the thickness of the metal by means of a projection or boss on the valve
below the seating of an angular or conical form, the opening in the metal being also
of angular or conical form, so that when the valve is down upon its seating the
whole space is filled up, the projection of the valve being nearly in contact with
the sides of the opening, and when the valve is lifted off its seating the sides of
the projection recede from the sides of the opening by reason of its angular form,
leaving an enlarged space for the passage of the gas or air.
I prefer to make the valves of circular form, but they may be made of rectan-
gular or any other convenient form, and the projecting ends may be made to take
the guiding pins, being hollowed out for that purpose.
It is also essential that the piston should approach the cover so closely at the end
of its stroke, in order to discharge the whole or as nearly as possible the whole of
the compressed gas, that great risk would arise of the piston coming in contact with
the cover, and so causing injury to the apparatus, or breaking the joint of the cover.
In order to prevent this, according to one arrangement, I face the piston with
india-rubber or with a.plate cushioned on india-rubber,

page_text: Another mode of effecting this object is to apply in connection with the cross head
outside the cylinder a powerful spring, the strength of which is so adjusted as to
stand rigid against the intended maximum working pressure in the compression
cylinder, but to yield or give way to any excess of pressure or undue strain.
In connection with the india-rubbor I also propose to render the piston rings self-
expanding, in proportion to the pressure in the cylinder, by bringing the inner
surfaces of the piston rings into contact with or so applied to the outer periphery of
the india-rubber discs or rings that pressure applied to the face of the latter is
transmitted radially to the piston rings, and so presses them outwards.
Considerable difficulty has been experienced with the piston working in a closed
cylinder in engines for compressing gases, especially where great pressures are used,
owing to the difficulty of maintaining the pistons perfectly tight, and the conse-
quent escape of gas from the pressure side to the intake side of the piston, which
fills up space on the intake side that should be occupied only with the new charge
of gas entering the cylinder, and thus causes a great per-centage of loss in the total
volume of gas compressed.
In order to avoid this difficulty I use, in lieu of the enclosed piston, a plain ram
or plunger working in a cylinder bored accurately to fit it, with piston rings or
packing of the description above referred to at the end of the ram, and also a gland
packing at the front end of the cylinder where the ram enters it. By this means any
leakage past the ram piston passes into the outer air, and not round to the intake
side, and can be at once detected and checked by closing in the gland.
Two rams, bolted or otherwise connected together, may be employed working in
two cylinders placed opposite one another, thus making a double-acting machine,
and the cushioning arrangements above described applied thereto, or the cushioning
may be effected by means of a thick slab of india-rubber inserted at the connection
of the two rams, or to the cross head outside the cylinders, or by applying round
the bearings of the joint pin in the cross head a thick ring or rings of india-rubber.
I also make the rains hollow, so as to receive water, glycerine, or other liquid for
keeping them cool.
In order to maintain the glands perfectly tight, and at the same time avoid the
excessive friction arising from the ordinary description of screwed-up glands, I apply
to the glands a liquid or semi-liquid packing of glycerine or other substance, which
may serve to lubricate the ram, and I apply a pressure thereto sufficient to overcome
any tendency of the gas to escape through such packing. This pressure may be
applied by means of a weighted piston or plunger working in a chamber filled with
the fluid or semi-fluid substance, so that any waste or escape of the substance
is constantly being made up or supplied by the gradual descent of the ram, the
weight upon which is rendered sufficient to keep the packing tight against any
tendency of the gas to escapo, any of the packing substance that may escape being
returned to the ram chamber, and used over again.
Any convenient number of grooves may be used in the gland, filled with the fluid
or semi-fluid substance, and for additional security an ordinary screwed-up gland may
be applied at the exterior of the whole, which, owing to the checks effected by the
liquid glands, would not require to be so tight as to cause an undue amount of
friction, or the packing grooves may be filled with a paste composed of graphite or
black lead mixed with a sufficient quantity of glycerine or other suitable substance,
or may be filled with suet, soft soap, mercury, or any other suitable substance.
I also pack the gland by means of a thin sheet of metal bent round the rod or
the ram, outside which I apply an india-rubber ring, so that by applying pressure,
by means of a screwed-up gland to the edge thereof, the india-rubber is caused to
swell out, and press the metal sheet closer round the rod or ram.