It is well known that in all air compressors and water pumps the
pressure in cylinder of air compressors or in working barrel or cylinder
of pumps is much greater at the point of opening the delivery valves
than the actual pressure in the air receivers of compressors or in water
column of pumps because of the difference in area between the top and
bottom of delivery valves. In some air compressors a hundred and
twenty-five pounds pressure to the square inch is required in the
cylinder to eighty pounds in the receiver, and in some instances a
hundred pounds pressure is required in the cylinder to eighty pounds
pressure in the receiver or column.
The engraving shows an invention designed to remedy this defect in air
compressors and pumps, to provide a device which will enable the
compressors and pumps to operate with equal pressure on both sides of
the delivery valve.
The invention consists of an auxiliary valve arranged outside of the
cylinder, where it is not subjected to back pressure, and connected with
the delivery valve by a hollow valve stem.
In the engraving, which is a sectional view, the cylinder of an air
compressor is represented, on the end of which there is a ring
containing delivery ports, through which the air from the cylinder is
forced into a receiver or conducting pipe. This ring is provided with an
inner flange or valve seat on which rests the delivery valve. These
parts are similar to those seen in some of the air compressors in common
use, and with this construction and arrangement one hundred pounds
pressure to the square inch in the cylinder is required to open the
valve against eighty pounds pressure in the receiver or in the
conducting pipes.
[Illustration: AUTOMATIC BALANCE ATTACHMENT FOR DELIVERY VALVES OF AIR
COMPRESSORS AND WATER PUMPS.]
A drum having an open end is connected with the cylinder head by
inclined standards, and contains a piston connected with the valve by
means of a rod that extends centrally through the cylinder head. On the
outer end of this rod is screwed an adjusting nut, by means of which the
piston may be adjusted. This rod is bored longitudinally, establishing
communication between the compressor cylinder and the drum containing
the piston.
It will be seen that the upper face of the piston is exposed so as to be
subjected to atmospheric pressure only, and when the compressor is in
operation a portion of the air in the compressor cylinder passes through
the hollow rod into the space beneath the piston, and there exerts
sufficient pressure, in combination with the pressure on the inner face
of the valve, to open the valve against an equal pressure in the
receiver or conducting pipes, so that when the pressure in the cylinder
equals the pressure in the receivers the valve is opened and held in
place until the piston in the cylinder starts on the return stroke, when
the pressure under the piston is immediately relieved through the hollow
rod and the main valve closes.
The space between the valve and its seat is made as shallow as possible,
so that the space may be quickly filled and exhausted. The piston may be
adjusted to regulate this space. This invention was recently patented by
Messrs. Samuel B. Connor and Henry Dods, of Virginia City, Nevada.
* * * * *