US2233979A - Pump - Google Patents

Description

A. G. HORVATH PUMP Filed Feb. 8

March 4, 1941 1940 2 Sheets-Sheet 1 LEE? luvau-row 'Amuom (1. Hum my AnoRuEYg March 4, 1941. A. G. HORVATH 2,233,979

PUMP

Filed Feb. a, 1940 2 Sheets-Sheet 2 [NVENTOR ANTHONY C1. HORVATH ATTQRNEYS Patented Mar. 4, 1941 UNITED STATES PATEN OFFICE PUMP Application February 8, 1940, Serial No. 317,909

2 Claims.

This invention relates to a variable delivery pump.

It is an object of this invention to provide a constant speed variable delivery pump.

It is a further object of this invention to provide a pump wherein the capacity is varied directly by the pressure in the tank and indirectly by the quantity of fluid in the tank.

It is a further object of this invention to provide such a pump wherein starting and stopping is reduced to a minimum and wherein there is a constant pressure on the delivery end of the pump irrespective of the variation in the quantity of fluid supplied by the pump.

It is a further object of this invention to provide by-pass means between the pressure chamber and the air chamber.

It is a further object of this invention to provide such by-passmeans as will connect the air chamber and one of the pressure chambers of a double acting pump having twochambers.

It is a further object of this invention to provide such by-pass means as will connect the air chamber with one of the pressure chambers of the double acting pump having two such chambers and to provide pressure responsive means between the air chamber and the other pressure chamber which will vary the capacity of the air chamber during the operation of the pump.

It is a further object of this invention to provide such means which will vary the fluid delivery inversely with the delivery pressure.

Lt is a further object of this invention to provide pressure responsive means between the air chamber and both pressure chambers in order to vary the capacity of the air chamber of a double acting pump having two pressure chambers.

It is a further object of this invention to provide such means which will periodically vary the capacity of the pump, which means is responsive to the pressur diiferential between the air chamber pressure and the respective pressure chamber pressures in order to vary the fluid delivery of the pump inversely with the delivery pressure.

It is a further object to provide means whereby a part of the fluid from a pressure chamber to the air chamber is by-passed to the other pres sure chamber and the return of this by-passed fluid is controlled or varied according to, the amount of air pressure in the air chamber whereby, when the pressure in the air chamber is decreased, the amount of this by-passed fluid is decreased and vice versa.

It is a further object of this invention to provide means for varying the capacity of the air chamber directly with the pressure at the pump delivery whereby the quantity of fluid delivered by the pump will be varied inversely with the pressure at the pump delivery.

It is a further object of this invention to provide a pump wherein the amount of fluid returned from the air chamber to the pressure chamber on the suction stroke varies according to the pressure in the tank.

It is a further object of this invention to provide a pump adapted for constant operation during delivery with a minimum of starting and stopping and with a wide range of supply without starting or stopping and a high gallonage of delivery per hour per horsepower.

It is a further object of this invention to provide an air cushion, a combined air and water cushion and means of relieving the fluid pressure delivery and the starting and stopping operations with a consequent saving on the pump and motor.

These and other advantages will appear from the following description taken in connection with the drawings.

In the drawings:

Figure 1 is a side elevational view, partly broken away, of a pump according to my invention;

Figure 2 is an end elevational view of the pump shown in Figure 1;

Figure 3 is a sectional view of the air chamber of the pump, but with all of the removable parts unscrewed from the casting;

Figure 4 is a cross sectional view taken along line 4-4 in Figure 6 and looking up into the pump in the direction of the arrows;

Figure 5 is a sectional View taken along line 5-5 in Figure 6;

Figure 6 is a fragmentary sectional view of the structure shown in Figure 1 with the parts in one of the operating positions.

Referring to the drawings in detail, and in particular to Figures 1 and 2, I designates a pump sub-base upon which is secured a pump casting 2, in which is integrally formed at one end thereof crankcase 3, motor platform 4 and cro-sshead guide cylinder 5. At .the other end of the casting, integrally formed therein, is a suction inlet chamber 6 having a pair of intermediate chambers l and la disposed at opposite sides thereof. Provision is made for the attachment of suction inlet 8 at one side of the suction chamber 6. The suction inlet is also attached to a primer vacuum chamber 9 which is equipped with suitable interior suction strainer screen (not shown) and at the top with a priming plug and at the bottom with a cleanout plug H.

Suitable bearings are provided in the crankcase portion of the casting 2 for support of crankshaft l2 which is operatively connected by means of connecting rod l3 to the crosshead I 4 which is mounted for reciprocation in the crosshead guide cylinder 5. Disposed on the motor platform 4 is a motor l or other suitable prime mover, which is operatively connected to the pulley l6 which is rigidly attached at one end of the crankshaft I2. By this means the crosshead I4 is caused to reciprocate in the crosshead guide cylinder 5 during operation of the prime mover;

Attached at one end to the crosshead I4 and disposed axially thereof is a piston rod I1, which passes through a fluid deflector l8 at the end of the crosshead guide cylinder 5, which deflector prevents the entry of fluid on the piston rod l1 into the crosshead guide cylinder 5 and thence to the crankcase. Extending across the suction chamber 6 is an open ended cylinder 20 which has its opposite ends opening into the respective intermediate chambers I and la. A stufling box 2| is threadedly attached to the outer wall of the intermediate chamber 1 and. the piston rod l1 which is axially disposed with respect to the stuffing box 2| and the cylinder 29 extends through the stuffing box and has the piston assembly 22, which is adapted to reciprocate in the cylinder 24!], attached to the threaded end thereof. The casting 2 terminates above the suction chamber 6 and intermediate chambers 1 and 1a in a flat wall, to which is attached the casting 23 forming the pressure chamber as a whole, which is divided into two parts or pressure chambers 25 and 25a respectively by the dividing wall 24. The pressure chamber 25 is connected by means of port 26 with the intermediate chamber 1 and the pressure chamber 25a is connected by means of port 26a with intermediate chamber Ja. A piston plug 28 equipped with a "Schrader valve 21 and of a diameter suitable to provide easy access 'to the cylinder and piston assembly is threaded into the outer wall of the intermediate chamber 1a. The pressure chamber 25 is connected by means of suction valve assembly 29 with the suction chamber 6. The pressure chamber 25a is connected by means of suction valve assembly 290. with the suction chamber 6. The casting 23 has a top wall upon which is. suitably secured a casting forming an air chamber 30 having a priming plug 3| screw-threadedly attached at the top thereof and having a delivery outlet 32 offset therefrom, which is adapted to be connected to a conventional tank in a fluid system in which the pump is connected.

Screw-threaded in the air chamber 30 and disposed above the outlet 32 is a choker nipple 33 which supports a conventional pressure switch 34, which is connected by means of cable 35 with motor [5 and which responds to pressure in the air chamber to stop and start the motor l5 in a known manner. The interior of the air chamber 30 is equipped with a horizontal wall 36 having a constricted port 31 therein. The air chamber 39 is connected to the pressure chamber 25 by means of discharge valve assembly 39. The air chamber 30 is connected to the pressure chamber 2511. by means of discharge valve assembly 39a and by-pass orifice 38a. 7

The valve assemblies 29, 29a, 39 and 39a are identical comprising apertured plates cooperating with resilient valve plate members resiliently urged thereagainst by means of springs, the resilient valve plates being guided by vertical posts attached at one end to the apertured plates and having the upper headed end thereof adapted for abutment with the upperend of the spring which has its lower end in contact with the resilient valve plate. Suitable gaskets are provided between the air chamber and the casting 23 and between the casting 23 and the casting 2 as well as between the stufling box '2land the latter casting and between the piston plug 28 and the latter casting so that the escape of fluid at all joints is effectively prevented.

The suction chamber is connected through the primer vacuum chamber 9 to a source of fluid supply and fluid is pumped from the suction chamber 6 through the suction valves 29 and 29a to the pressure chambers 25 and 25a and thence through orifice 38a and discharge valves 39 and 39a to the air chamber 30 and thence through outlet 32 to a suitable tank, or, if desired, directly to the fluid system. While an electric motor is shown and described as the prime mover, it is, of course, to be understood that the principles of my invention may be practiced by the use of other desired prime movers and that the principles thereof may be incorporated in pumps of other constructions than that shown and described, the constructions of which may vary widely and it is, therefore, to be understood that the description and illustration of the particular pump is made for purpose of illustration only and it is in no wise to be considered as limiting.

Operation With reference particularly to Figure 6, it will be seen that fluid enters the suction chamber 6 from the suction inlet 8 and from thence the path of the fluid is as follows: when the piston is moving toward the left in the cylinder 20, compression is placed upon the fluid in intermediate chamber and it travels thence through pressure chamber 25 and through discharge valve 39 which is opened by the fluid into the air chamber 30, from whence the main part of the fluid is discharged through outlet 32,v a part thereof passing through the by-pass orifice 38a. to the chamber 25a which is then under suction. The amount of this fluid passing through by pass orifice 38a varies directly with the difference in pressure between the air chamber 30 and the chamber 25a. Simultaneously, fluid is drawn into chamber 25a through suction valve 29a because of the suction in intermediate chamber la caused by the leftward movement of the piston in the cylinder 20.

When the piston is traveling in the reverse or rightward direction, compression is placed upon the fluid in chamber la and in pressure chamber 25a and the fluid flows from chamber 25a into the air chamber 30 through valve 390, and also through the by-pass orifice 38a. The by-pass orifice, on this stroke of the pump, thus aids the valve 39a.

The pressure in the air chamber 30 is equal to the pressure in the tank to which the outlet 32 is connected. The pressure switch 34 is responsive to this pressure. As will be clear from the above description of the operation, the difference between the pressure in the air chamber 30 and the pressure in the chamber 25a, during leftward travel of the piston in cylinder 29, determines how much fluid will be returned from the air chamber 30 through the by-pass orifice 38a during operation of the pump. Thus, when the pressure in the air chamber 39 is relatively low, the proportion of the fluid pumped from a pressure chamber to the air chamber on a particular leftward piston stroke will be greater than when the pressure is relatively higher. The effectiveness of the by-pass orifice to reduce the rate of delivery varies, therefore, directly with the pressure in the air chamber 30. Thus it will be seen that, when a relatively large quantity of fluid is being drawn from the tank, the pressure in the air chamber will be correspondingly reduced and a relatively greater proportion of the total fluid pumped per stroke from the pressure chamber to the air chamber will flow out through the delivery outlet 32. Likewise, when a relatively small quantity of fluid is being drawn from a sys tern, the reduction in pressure in the air chamher will be correspondingly less and a correspond ingly smaller proportion of the fiuid pumped per piston stroke from the pressure chambers to the air chamber will flow through the outlet 32.

It is therefore apparent that the function of the orifice 38a is to permit a circulation of water from the air chamber 30 to the pressure chamber 25a. In accordance with the pressure of the airin the air chamber, the greater this pressure the more will be the quantity of water passing through the orifice 38a. It is therefore necessary that the orifice shall be of such size as to accommodate as much water as is necessary to by-pass determined by the air pressure in the air chamber 3%. The orifice should not be any larger than is necessary to serve this purpose. Since when the volume of the discharge is practically equal to the total capacity of the pump, little or no water should be by-passed through the orifice, because the water re-circulating under these conditions would represent a loss in efficiency of the pump. It should be noted in this connection that the area of the delivery outlet 32 is so much greater than the area of the orifice 38a and is presented more directly to the water in the air chamber 30 that the tendency would be to cause practically all of the water to flow through the outlet 32 under these conditions, and little or no water will flow through the orifice 38a to be re-oirculated. On the other hand, when the delivery of the pump has been severely curtailed, thus tending to build up a sufficiently high pressure in the air chamber 38 the orifice 38a must be suificiently large to accommodate all of the water that is necessary to be by-passed in order to maintain the air pressure in the air chamber at a predetermined constant value. This air pressure acts directly on the volume of water between the air chamber and the orifice, so as to force water through the orifice in a quantity determined by that pressure.

The size of the orifice 38a will vary in accordance with the size and capacity of the pump and also in accordance with the pressure that is desired to maintain in the air chamber within a predetermined range of variation in the quantity of fluid being drawn from the outlet 32.

As one typical example of the size of the orifice compared to the other major dimensions of the pump which has been found to operate extremely satisfactory, the following dimensions are cited:

Approximately 60 volume of the cylinder 2% and the inlet chamber 6) cubic inches Approximately 13 Size of the orifice 38a square inches" .0123

(one-eighth of an inch in diameter) Expressed in still another Way and based on the proportion of the by-pass opening and the volume of the air and pressure chambers, the volume of the Air chamber is 4860 X the area of the bypass orifice and the volume of the Pressure chamber is approximately 1050 x the area of the orifice.

The size dimensions on which the above figures are based, are given in the patent drawings in case it is desirable to work out any other proportions between the size of the orifice Ella and the air or pressure chamber.

From the above it will be appreciated that the size of the orifice is quite substantial and is adapted to pass considerable quantities of recirculating fiuid particularly when the pressure in the air chamber is considerable. The pressure in a pump of the dimensions given above may range from between 25 and 451bs.per square inch, may be set at an average value of approximately 25 lbs. per square inch, depending on the size of the orifice 38a and the speed of the pump, etc., and it will be noted that as this pressure tends to rise to say 45 lbs-- per square inch due to a less demand for water at the delivery outlet 32, a very considerable quantity of water will be caused to flow through the orifice 38a until the pressure is restored to 25 lbs. per square inch or any other predetermined value.

It will be understood that the orifice 38a operates most effectively to by-pass water within the pump when the rate of flow at the delivery outlet is varied within particular limits. It is not intended that the orifice 38a should accommodate enough by-pass fluid to maintain a considerable pressure in the outlet, when the outlet 32 is completely shut Oil. For this reason the pressure switch 34 is provided to stop the motor when the pressure in the air chamber reaches such a value as cannot be accommodated by the orifice 38a by way of increased recirculating flow of water.

The maintenance of a considerable pressure in the air chamber, notwithstanding a variation in the rate of discharge, is obtained by a continual operation of the pump. It will also be understood that whereas an orifice of one-eighth of an inch in diameter in a pump having the dimensions given above, will adequately take care of a 1b. differential in the air chamber. It is apparent that a larger size orifice may be provided to accommodate even greater changes in excess pressure. Inasmuch as the size of the orifice determines, at least in part, the air pressure in the chamber 30, the orifice also determines the maximum out-put or capacity of the pump, but in this connection it will be noted that within this capacity and regardless of the amount of water being withdrawn the pressure in the delivery outlet 32 will be substantially constant notwithstanding the fact that the pump is being continually operated.

It will be evident that, besides producing a variable capacity in a constant speed pump, I have produced a new method of operation, by which the starting and stopping of the pump is reduced to the minimum which amounts to a great savings in power consumed and in wear upon the respective parts due to the well recognized fact that frequent starting and stopping produces a relatively greater amount of wear than does uniform operation. It will further appear that by the incorporation of the principles of this invention in a pump, the capacity thereof will be substantially increased whereby a smaller pump may be used for a predetermined load than has hithertcbeen possible and likewise a more economical operation may be achieved due to the fact that a smaller prime mover will be necessary than otherwise.

It will be understoodthat the above described structure is merely illustrative of the manner in which my invention may be carried out and that I desire to comprehend within my invention such modifications as come within the scope of the claims and the invention.

Having thus fully described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In a water pump having an air chamber and a pumping chamber adapted to supply fluid thereto, constantly operative means for maintaining the pressure at the discharge of the pump substantially constant regardless of the 'rate of discharge, said means including a by-pass opening between the air and pumping chambers, said opening being of such size as to prevent a substantial change in pressure in the air chamber as the rate of discharge is substantially changed, said opening having an area of approximately .0123 square inch when the air chamber has a volume of approximately 60 cubic inches and the pressure chamber has a volume of approximately 13 cubic inches.

2. In a water pump having an air chamber and a pumping chamber adapted to supply fluid thereto, constantly operative means for maintaining the pressure at the discharge of the pump substantially constant regardless of the rate of discharge, said means including a by-pass opening between the air and pumping chambers, said air chamber and pumping chamber having the following proportional volumes and the by-pass opening having the following proportional area:

Air chamber 4860 Pressure chamber 1050 By-pass opening 1 ANTHONY G. HORVATH.

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