US2450751A - Constant flow pump - Google Patents

Description

C. A. ELWOOD CONSTANT FLOW PUIIP Oct. 5, 1948.

Filed larch 7, 1946 2 Shoots-Sheet 1 INVENTOR A'ITORNEYfi CALVIN A ELWOOD Oct. 5, 1948. c. A. ELWOOD cons'mu r FLOW PUMP 2 Sheets-Sheet 2 Filed March 7, 1946 D. m w m. mm 0 M m A m z. .W .m c B. 3 o Z :4 m M U2 1 0 J .o& 2 d W I. "Q I H w proved patent vention;

Patented on. s. 194.8

Calvin A. Elwood, Rochester, N. 'y., assignor 'to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey Application mmll '1, ms, Serial No. osasos This invention relates to pumps, and particularly to pumps designed to deliver-a substantially constant flow of fluid. One object of invention is .to provide a pump by which fluid may be moved at a substantially uniform rate and in which the usual pulsations are reduced to a minimum or are eliminated. Another object of my invention is to provide a pump in which one cylinder is arranged to deliver fluid in surges to a chamber to which a second cylinder is connected in such amanner th t the pulsating'st'rokes of the flrst strokes of the second cylinder to deliver a subcylinder ar offset by the pulsating stantially constant flow oi'fluid. A still further objectof my invention is to provide a simple type I of hydraulically-operated pump particularly adapted for use in feeding fluids which must'not' be contaminated through contact with lubricated pump part other objects will appear from the following specification, the novel features being particularly pointed out in the claims atthe end thereof.

My pump is for an improvement over the me- 8Glaims. (01. 103 -44) i 2 -Flgrais a section taken on line 3-3 of Fig. '1, parts being shown in elevation; 4

Fig. 4 is a schematic part-section and partelevation view illustrating the principle of my improved pump, and I Fig. 5 is a diagram illustrating the results obtained with my two-cylinder pump in terms of fluid pumped. Y

' My invention comprises broadly a hydraulically-operated pump in which a main cylinder is arranged to deliver surges of fluid in a pulsator as a piston moves pulsating fluid to and from a cylinder-while moving with asimple harmonic motion. At the same time a second pulsator. which includes a cam-operated piston, causes pulsating fluid to move to and from a flow chamber in such a manner that the fluid delivered from the flow chamber is moved at a substantially constant rate. If it were not for the limitations but in order to produce a cam-driven pulsator tering' pump shown in U. 8. Patent 2,313,551,1Hurlbut, granted March 9.1943, and a portion of my pump closely resembles, in, many respects, thepump shown in this patent. However, my imform of pump diflers from the Hurlbut that the fluid delivered in surges by one cylinder is turned into a substantially constant delivery flow through the use of a second cylinder con- I nected into the system.

I am aware that it is not broadly new to pro- V168 relation, since such a pump is shown'in British two hydraulic cylinders operating in timedin that I utilize twocylinders so arranged Patent 7,172, Carruthers, May 8, 1890. This patv ent shows a two-cylinder hydraulic pump of the general type I am using, but in this patent one cylinder delivers a surge of fluid during one stroke, and the second cylinder delivers a. second surge oi-ii'uid during a second stroke. The two cylinders are not arranged as the surge of one cylinder is oflset by the surge in thesecond cylinder.

Coming now to the drawings whereinlike reierence characters denote like parts throughout:

Fig. i isa side elevation of a pump, certain details being omitted, constructed in accordance with and embodying a=preferred form of my in- Fig. 2 is a top plan view of the pump shown in Fig. 1 with certain parts in section and shown somewhat diagrammatically;

E my invention. so that imposed'by mechanical designs of, cams. a perfectly even delivery of fluid could be obtained,

which will withstand wear, a pump can be produced in which there is a scarcely noticeable pulsation at-one point and for most purposes this can be considered an even delivery of fluid.. Valve design also enters into this problem as an instantly closing valve is generally not obtainable, so that minute variations in flow may result from differential time lag in'valve operation. It is comparatively diflicult from the practical stand-.

point to detect the slight variation in flow which may occur with the pump which will now be more fully described.-

' Referring to Fig. 1, the. pump may include a base i from which a frame -plate 2 extends upwardly, this frame-plate carrying a cylinder 3,

in which a'piston 4 may be moved back and forth with a simple, harmonic motion by cans of a crank 5. This crank is pivoted at 8 to the piston sand driven-by an eccentric 1 carried and driven by a power-driven shaft 8. While mechanism including set screw l2, handwheel l3 and bevel gears 9 and III are provided for altering the position of eccentric I relative-to shaft 8 to vary its stroke, this is only a factory adjust- ,ment and the stroke will always remain the same with any given cam. l8. Gear Ill turns screw it carrying the eccentric 1., v

The shaft 8 is connected by means of spiral gears l4 and I! to a vertical shaft it. A similar pair of gears It and i 5' driyes a shaft ii to which a cam i8. is keyed, as shown in Fig. 3. From Fig. 1 it will'be noted thatthe cam i8 is provided with a cam slot is in which a roller 20, carried reciprocating link may drive a piston 22 enter-' ing the cylinder 23. 'The reciprocating link 21 may move in a suitable guideway 24, as best shown in Fig. 3; this guideway being carried by bracket 25 attached to a base plate 26, this plate in turn being preferably attached by screws or bolts 21 to the frame plate 2. The vertical shaft it may be driven by any suitable source of power such as motor .56. The two pistons are therefore driven in synchronism by the same power drive.

. The cylinder 3 is provided with a fluid outlet' 30, this fluid outlet, as indicated more or less diarammatically in Fig. 4, being connected by means of a pipe 3| to a pulsating chamber'32. This pulsating chamber is provided with a flexible diaphragm 33, a fluid-inlet means consisting "A? continuing upwardly along the lines al, a2, a3, and ending at B, this area designating the displacement of fluid due to the piston stroke in one direction. The return stroke of the cylinder may be designated as "B," bl, b2, b3, and C. Thus, if the single cylinder 3 were used as a pulsator, the pumped fluid would be delivered-in the surge designated broadly as B during its stroke from A" to B" and, of course, the inlet and outlet of a valve 34 and a fluid-outlet means consisting of a valve 35. These two valves are one-way valves and they may be conveniently made of sheets of perforated flexible material, the perforations 38 and 31 being positioned to lie'against valve seats 38 and 33 which are apertured at '40 and H to permit surges of the fluid being pumped to pass through the pumping chamber. The inlet opening 40 is connected by a pipe 42 to a supply of fluid 43 and this supply should be positioned to eliminate any appreciable head of fluid enter-' ing the pipe 42.

At the end of the outlet valve 35 there is a flow chamber 44 in which there is a flexible wall 45. This flexible wall is positioned in accordance with the flow of pulsating fluid to and from the chamber 44 through the opening 46, pipe 41, and the fluid exit 48 of the cylinder 23. This backand-forth pulsating flow is caused by the piston 22 which, as above described, is moved by a cam path l3 and a roller as above described.

From the flow chamber above valve 35 a delivery tube 49 leads, in this instance, to a tray 50 so that the fluid 5| being pumped may be maintained substantially at the desired level L. In the present valves would be closed and no fluid would be delivered between its stroke from "B" to "C."

. To even out this flow, the equalizing cylinder 23 is provided with a cam drive which moves the piston 22 differentially with respect to the piston 4 to offset the surge of the cylinder 3 to such an extent that an even, or substantially even, flow is delivered from the flow chamber through the pipe 49. The cam i3 is so designed that the cylinder 23 may deliver pulsating fluid to the flow chamber 44 above the flexible diaphragm as indicated in the diagram, Fig. 5, as follows: Starting at D, the stroke of the piston 22 will displace fluid as shown by the line dl, d2, d3, ending at "E," and continuing along the line el to "F. The volume of the roughly triangular area V2 is equal in area to the volumeof the roughly triangular section V3 so that the first twenty degrees of the two strokes are equalized. The volume V is greater than the volume VI by an amount equal to the area, H, I, J, and K. Thus, the stroke invthe main cylinder delivers a quantity of pulsating fluid which is even because the surge is offset by the compensating cylinder 23 altering the size of the flow chamber 44.

The roughly triangular areas V4 and V6 oflset each other, and the areaVb indicates an even quantity of pulsating fluid delivered by the cylinder 23 during the time of the return stroke of the main cylinder 4, the volume being delivered from the flowchamber 44 due to movement of flexible wall 45. In order to indicate the timing of the Table of function as it passes through the pump. It should also be noticed that the pulsating fluid, which is oscillated by the pistons and cylinders, is kept entirely separate from the fluid being pumped, and that the two cylinders operating in timed relation will oscillate the pulsating fluid in the pump and flow chambers as will be hereinafter more fully described. As-shown in Fig. 4, the vertical shaft l3 may be driven through a gear reduction contained in the housing from a motor 56.

Referring now to Fig. 5, the pulsating flow of the main pulsating cylinder 3, which as above explained is driven in a simple, harmonic motion, is shown in the diagram by the area starting at Pump 3 $3 Diaphragm 33 Inlet Valve 36 Outlet Valve 36 Diaphragm 45 Outlet 49 0-20 Pressure Pressure" Contracts (Shown) Closed (Shown)... Open (Shown)- Pressure (Shown).-- Uniform Flow. 20-l60 Pressure Suction.-. Contracts Closed Open Suction. .i.. D0. l60i80. Pressure Pressure" ..do. -.do .do Pressure. Do.

' l80-369- Suction.-. do Exp n Open Closed Do.

I have illustrated by the diagram of Fig. 5 and the above Table of function the relationship of the two cylinders when one is driven by a simple, harmonic motion since I prefer this construction because, in addition to furnishing the fluid to the mainpulsating chamber 32 and to the flow cham- 80 her 44,the construction of the pump must be such that-the inlet valve 34 and the outlet valve 35 will open and close smoothly in the proper relation. It is obvious, particularly from the Chart of function." oflset in such a manner that when the material being pumped passes too rapidly into the flow chamber 44, the size of this chamber will be increased, and when the fluid is pumped either too slowly, or is not pumped into the flow chamber, the diaphragm 45 will be moved by the cam-operated piston 22 from the chamber in.an even flow through the pipe 49. It is obvious to one skilled in the art that other means of operating the istons may be designed and each piston-may be driven by a that the strokes of the two cylinders areto expel the fluid being pumped i cam instead of having ,-simple, harmonic motion although I prefer this one piston moved with a later motion because oi its desirable action upon the inlet and outlet valve.

WhereI- refer to a "constant or even flow in the specification and claims, I mean this term to be considered as including a substantially con-- starit or substantially even flow as there are liable to be slight deviations from an exact or precise even or constant flow, which may be due to either valve operations or cam design, or both. Nevertheless, the flow is such that an extremely uniform delivery of the pumped fluid may be maintained and for practical purposes it is constant. The fluid being pumped never comes in contact with parts of the pump which need to be lubricated and, therefore, cannot become contaminated.

While I-have described a preferred embodiment of my invention, it is obvious that'various changes can be readily made therefrom without departing from my invention as defined in the following claims.

outlet end communicating with the outlet means of the suction chamber, a, delivery pipe leading from the flow chamber, a flexible wall in the'flow chamber, pistons and cylinders for moving a pulsating fluid to and from the pulsating chamber to exert pressure upon the flexible suction chamber and to and from the flow chamber to exert pressure on the flexible wall in the flow chamber, and means for correlating the respective strokes of the pistons to deliver a constant even flow or fluid through the delivery pipe.

2. A hydraulically driven pump, comprising, in

inlet and outlet means leading to and from the flexible suction chamber, a flow chamber at the outlet end communicating with the outlet means of the suction chamber, a deliverypipe leading i'rom the flow chamber, a flexible wall in the flow chamber, pistons and cylinders for moving a pulsating fluid to and from the pulsating chamber to exert pressure on the flexible suction chamber and to and from the flow chamber to exert pressure on the flexible wall therein, and means for correlating the respective strokes of the pistons to deliver a constant even flow of fluid through the delivery pipe, said means comprising a source of power, and means for diflerentially driving one piston with respect to the other to offset the :surges produced by the other piston.

8. A hydraulically driven pump, comprising, in combination, a flexible suction chamber, a hollow pulsating chamber carrying the suction chamber, inlet and outlet means leading to and from the piston with respect to theother and a general- 1y opposite direction and to a difleren't extent whereby the surges of one piston stroke may be ofiset by the surges oi the other piston stroke. 4. A hydraulically driven pump, comprising, in combination, a flexible suction chamber, a hollow pulsating chamber carrying the suction chamber, .inlet and outlet means leading to and from the flexible suction chamber, a flow chamber at the outlet end communicating with the outlet means .of the suction chamber, a delivery pipe leading from the flow chamber, a flexible wall in the flow chamber, pistons and cylinders for moving a pulsating fluid to and from.- the pulsating chamber to exert pressure on the flexible suction chamber and to and from the flow chamber to exert pressure on the flexiblewall therein, and means for correlating the respective strokes of the pistons to deliver a constant even flow oi fluid through the delivery pipe, said means comprising a source of power, and means for differentially driving one piston with-respect to the other, the/stroke of one v piston being substantially twice that of the other piston and in an opposite direction thereto.

5. A hydraulicallydriven pump, comprising, in combination, a flexible suction chamber. a hollow pulsating chamber carrying the suction chamber, inlet and outlet means leading to and from the flexible suction chamber, a flow chamber at the.

outlet end communicatinglwith the outlet means of the suction chamber, a delivery pipe leading from the flow chamber, a flexible wall in the flow chamber, pistons and cylinders for moving a pulsating fluid to andirom the pulsating chamber for exerting pressure on the flexible suction chamber and to and from the flow chamber to exert pressure on the flexible wall therein, a source of power for driving the pistons in synchronism, at

. least one piston drive comprising a cam shaped 40-to move said piston to oflsetthe suites in the combination, a flexible suction chamber, a hollow pulsating chamber carrying the suction chamber,

pumping chamber caused by the other piston whereby a substantially constant flow may be obtained from the deliverypipe. I

6. A hydraulically driven pump, comprising,,in combination, a flexible suction chamber, ahollow pulsating chamber carrying the suction chamber,

flexible suction chamber, a flow chamber at the outlet end communicating withthe outlet means 0! the suction chamber, a delivery pipe leadingfrom the flow chamber, a flexible wall in the flow chamber, pistons and cylinders for moving a pulsating fluid to and from the pulsating chamber to exert pressure on the flexible suction chamber the delivery pipe, said means comprising a source oi power, and-meansfor differentially driving one inlet and outlet means leading to and from the flexible suction chamber, a flow chamber at the outlet end communicating with the outlet means of the suction chamber, a delivery pipe leading from the flow chamber, a flexible wall in the flow chamber, pistons and cylinders for moving a pulsating fluid to and from the pulsating chamber to exert pressure on the flexible suction chamber and to and from the flow chamber to exert pres-' sure upon the flexible wall therein, a source of power, a crank driven thereby for moving the piston relative to the cylinder connected to. the pulsating chamber, a cam'driven by the source of power for moving the piston relative-to the cylinder connected tothe flow chamber to alter the position of the flexible wall therein to compensate for changes in shape oi the flexible suction cham- 'ber to reduce surges passing through the delivery pipe.

7. A hydraulically driven pump, comprising, in

combination, 'a flexible suction chamber, a hollow pulsating chamber carrying the suction chamber, inlet and outlet means leading to and from the flexible suction chambena flow chamber at the outlet end communicating with the outlet means of the suction chamber, a delivery pipe leading from the flow chamber, a flexible wall in.

the flow chamber, pistons and cylinders ior pulsating a pulsating fluid team from the pulsatin: chamber to exert pressure on the flexible suction chamber and to and irom the flow chamber to exert pressure upon the flexible wall therein. a source of power means carried thereby to dii rerentially drive the pistons to deliver difl'erential flows oi pulsating fluid to the pulsating and flow.

chambers whereby the fluid delivered from the flow chamber maysbe substantially constant.

8. A hydraulically driven pump comprising, in combination, a hollow pumping chamber. a flexible suction chamber therein, dividing the pumppiston of the first cylinder with a simple, har-. monic motion. a cam-tor drlvin: the piston oi the. I second cylinder in timed relation to the movement oi the first cylinder. Piston at varying accelerationsr-whereby the flexible wall '0! the flow chamber may be moved tooffset the surges oi the piston moved with a'simple, harmonic motion.

' and a delivery pipe loading from the pumped fluid compartment oi the flow chamber to deliver a substantially even flow oi the pumped solution therefrom.

nnrmsnces crren The toilowinu references are or record in the file of this patent:

Uurrein sums Perms Number I Nam'e Date 20 2,186,972 Hollander et a1. Jan. 18, 1940 2,204,854 Hambly June 18, 1940 2,307,566 Broune Jan. 5, 1943 2,313,551

Hurlbut Mar. 9, 194a cnnvm nnwoop. i

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