Improvements in Air Compressing Pumps.
Year: 1891

page_text: Date of Application, 15th Sept., 1891-Accepted, 17th Oct., 1891
COMPLETE SPECIFICATION.
Improvements in Air Compressing Pumps.
A communication from abroad by LOUIS J. GENETT, of Marquette, in the County
of Marquette, State of Michigan, United States of America, Mechanic.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E. of the Agency for
Foreign Patent Solicitors, 6 Lord Street, Liverpool, and 6 Bank Street,
Manchester, both in the County of Lancaster, and 323 High Holborn in the
County of Middlesex, Civil Engineer, do hereby declare the nature of this
invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement:—
This invention consists in an improvement in air compressing pumps, hereinafter
fully described and claimed.
Figure 1 is a plan view,
Figure 2 is a section on line x-x, Figure 1, and,
Figure 3 is a central transverse sectional view.
A, represents a pump cylinder having a valve chest B on one face thereof, and
resting on the base plate R, to which it is secured by the bolt and nut r. T repre-
sents a piston rod passing through a suitable stuffing box, and engaging with the
piston within cylinder A. The piston rod T is intended to be actuated by a con-
necting rod (not shown) driven by any suitable source of power. () represents a
guide for the piston rod T, a sliding sleeve S connecting the piston rod with said
guide. M and N represent ports at the ends of the cylinder opening from the valve
chest into the cylinder A, for the entrance and exit of air into and from the cylinder.
I and J represent suction valves, which seat either by gravity as shown in the
drawings, or may be seated by springs if desired. The passages, which these
valves close, open to the outer air. C and D represent discharge valves which
control passages from the ports M and N to the outlet pipe P, which leads to a
suitable reservoir for compressed air (not shown).
Between the chambers of the valve chests into which ports M and N open, a
cylinder X is formed in which fits a tight piston E normally pressed to one end of
the cylinder by a spiral spring F. H represents a piston rod secured to piston E,
and carrying on its outer end a collar L. G G represent two oscillatory levers
pivoted at their centres to lugs on the valve chest, each of which is loosely pivoted
to pins i and j, which extend loosely into the air passages controlled by the suction
valves I and J respectively. U represents a nut which screws into cylinder X, by
means of which the tension of spring F may be regulated.
In the operation of an air compressing pump, it is desirable to have it compress
air to a determined pressure, and then to have the operation of the pump stop,
although the motion of the piston may continue, and have the pump automatically
resume operation when the pressure falls below the determined point. It is also
desirable while the pump is running but not compressing air, to avoid heating as
far as possible, and these two objects are attained by this invention, the operation
of which is as follows:-
Assuming the ports to be in position shown in Figure 2, and the piston rod T in
motion from any source of power, the motion of said piston rod to the right of
Figure 2 will draw air into the left hand of cylinder A through the ports N, the
suction valve I rising freely to permit the entrance of air to said ports. At the
same time the air in the right hand end of cylinder A is being forced out through
ports M, as shown by the arrows, into the valve chest, thus holding suction valve J
firmly to its seat, and raising discharge valve D, and causing the air to flow through
pipe P into the reservoir. The reverse motion of piston rod T will reverse this

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action, drawing external air into the cylinder through ports M, and forcing com-
pressed air through ports N and valve C into pipe P and the reservoir. The air
pressure in thetreservoir operates 'directly on piston E, and produces no effect
on said piston until the pressure of.air on said piston becomes greater than
the pressure of the spring F on the other side of piston E. When this occurs,
the piston E will be moved by the air pressure against the resistance of spring F,
and will thus move the piston rod H. and collar 1. This swings both levers G,
forcing the pins i and ; against the lower ends of the suction valves I and J
respectively, thus unseating said valves I and J, and throwing both ports M
and N into free communication with the external air, so that any air forced
out of cylinder A will pass freely out beneath valves I and J without passing
into pipe P, and this action will continue until the air pressure from the reservoir
on piston E becomes less than the pressure of spring F, when said spring will
force the piston E upwards, and permit valves I and J to fall to their seats, when
the normal action of the pump will be resumed. By this means when the pump
is doing no work, the cylinder A is constantly being filled with fresh cool air, thus
removing any tendency to heat.
Having now particularly described. and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, as communicated to me
by my foreign correspondent, I declare that what I claim is :-
1. The combination with the cylinder and the suction and discharge valve
chests of an air compressing pump, of a pair of suction valves and a pair of
discharge valves arranged in the valve chest, a cylinder located in the valve
chest between the suction and discharge valves, a piston arranged in the cylinder,
exposed to the air pressure created by the pump and held against said pressure
by a spring, and levers actuated by the piston to simultaneously unseat the two
suction valves when an excess of air pressure moves the piston against 'the tension
of the spring, substantially as described.
2. The combination with the cylinder and the suction and discharge valve
chest of an air compressing pump, of a pair of suction and a pair of discharge
valves in the valve chest, a cylinder located within the valve chest, between
the suction and discharge valves and opening at its upper portion into the ports
leading from the discharge valves to the discharge pipe, a piston arranged in
the cylinder, exposed to the air pressure created by the pump and held against
said air pressure by a spring, and oscillating levers acting at one end upon the
suction valves and at the opposite end acted upon by the piston in its downward
movement against the tension of the spring when an excess of pressure moves
the piston, substantially as described.
3. The combination with the cylinder and the discharge and suction valve
chest of an air compressing pump, of a pair of suction valves and a pair of
discharge valves in the valve chest, a cylinder located within the valve chest
between the suction and discharge valves, a nut in one end of the cylinder, a
piston arranged in the cylinder, having a piston rod passing through the nut
and exposed to the air pressure created by the pump, a spring interposed between
the piston and the nut, a collar secured to the piston below the nut and a pair
of oscillating levers pivoted to the valve chest and provided. respectively with
pivoted pins to lift the suction valves when the piston is moved. downward
against the tension of the spring by an excess of air pressure, substantially as
described.