US3179056A - Variable capacity positive displacement pump - Google Patents

Description

E- F. WRIGHT A ril 20, 1965 VARIABLE CAPACITY POSITIVE DISPLACEMENT PUMP s Sheets-sheaf 1 Filed Dec. 19, 1963 I NVEN TOR.

Z/ ///////l////II/// ELLIOTT F. WRIGHT FIG. 9

ELLIOTT F. WRIGHT NNNNNN O R.

April 20, 1965 F. WRlGHT-. 3,179,056

VARIABLE CAPACITY POSITIVE DISPLACEMENT PUMP Filed Dec. 19, 1963 3 Sheets-Sheet 5 PLUNGER VELOCITY K(l C05 FOR sMoo-rn FLow DUPLE! PUMP PLUNGER DISPLACEMENT K (ex-Sm 2a.) OPTIMUM VALVE SEATING mo creams 0 2O 6O 80 I00 120 Ma I I 7,00 220 :40 7.60 210 :00 31.0 340 360 EQUIVALENT cmux ANGLE-DEGREES (on TIME FOR cYcLE) PLUNGER DISPLACEMENT I.

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E uw ALEu'r CRANK ANGLE neensss (on TIME FOR CYCLE) ELLIOTT F. WRIGHT BY$0MQQ W United States Patent 3,179,056 VALE CAPACITY POSITIVE DIS- PLACEMENT PUMP Elliott F. Wright, Warren Township, Somerset County, N.J., assignor to Worthington Corporation, Harrison, NJ a corporation of Delaware Filed Dec. 19, 1963, Ser. No. 331,696 7 Claims. (Cl. 103-49) This invention relates to variable capacity positive displacement pumps and more particularly to a valve and throttle arrangement which facilitates obtaining optimum piston velocity throughout the working cycle or stroke of the pump.

Prior art concepts devoted to providing variable output from a constant speed power source such as magnetic drives, fluid couplings and stroke varying devices are costly and lack eifective means for reducing the cyclical flow variations and resulting pressure fluctuations inherent in pumps using a relatively small number of plungers or the like driven by a crank and connecting rod or their equivalent.

These pressure fluctuations are particularlyharmful to the valving of the pump. Specifically one of the results is slamming of the valves in opening and closing and accordingly very slow crank speeds are necessary.

There are also other reasons necessitating slow rotative speeds with conventional pumps. Another of these is due to the large variations in rate of flow of the combined cylinders. With any single reciprocating plunger the rate of flow is zero at each end of the stroke. To even out the combined fiow, multicylinder arrangements are used and in general the more cylinders used, the smoother the flow or the smaller the variations in flow. Another important speed limitation is caused by the need for keeping the piston accelerations down to values low enough to allow the liquid from the suction line to follow it on the' suction stroke. Where only atmospheric pressure is available in the suction line to provide acceleration of the liquid coming therefrom, which must work against the suction lift and other elements slowing it down, very little pressure remains for accelerating the liquid to follow the piston. As a consequence, voids in the cylinder result and destructive impacts caused by cavitation occur. I

Various prior art concepts have been devised to overcome the above mentioned defects in pumps of the type contemplated herein; for example, in United States Patent 2,528,131, the patentee has devised an unusual duplex valving arrangement with both valves driven by the rod on one side of the pump. He has insured full stroke of this side by using a spring biased snap action connection to the valve which is released only after the desired stroke length is reached. Through an entirely different mechanism the valve for the opposite side is moved quickly from full open one way to full open the other way just as the controlling piston passes mid-stroke.

Since there is no throttling past mid-stroke of the power fluid, it is believed that the moving piston would continue to move at constant velocity practically to the end of the stroke, stopping quickly while the other piston would accelerate to full velocity just as quickly. Accordingly, while certain of the defects mentioned above are overcome by applying the concepts disclosed in US. Patent 2,528,131, it is obvious that slow speeds are still necessary to limit the slamming caused by cyclical flow variations and the resulting pressure fluctuation.

Relatively small inexpensive variable capacity pumps with a large enough number of plungers or vanes, so the cyclical variations in flow are small enough to be negligible under most service conditions, are known in the art for use in applications wherein a clean hydraulic fluid is to be circulated, and it is an object of the present invention to use the hydraulic power available from such a pump to drive a direct acting pump at a variable speed from zero to maximum.

It is a further object to incorporate such a variable capacity pump with a direct acting pump so as to obtain overlapping of strokes and piston velocities essentially corresponding to the ideal pattern defined by The foregoing objects are accomplished by the present teaching of a variable capacity positive displacement pump including variable capacity driving means supplying power fluid to the pump at a desired pressure and further incorporating a control which interconnects the variable capacity regulating means to the pump and the control serves to maintain the motion of the piston of the pump in essentially a desired relation. This is accomplished by causing the motion of each piston to open the port to the opposite piston to an area portional to the velocity desired of that piston; and the total port area to the two pistons, like the desired sum of the velocities of the two pistons, remains constant. Additionally, a throttling means is also provided for obtaining an increase in pressure to start the movement of the piston that is affected by the influence of unbalance fluid valve area, static friction and inertia.

Other objects and advantages of the invention including the basic design and the nature of the improvements thereon will appear from the following descriptions taken in conjunction with the following drawings, in which:

FIGURE 1 is a diagrammatic view of a variable capacity positive displacement pump showing the present invention.

' FIGURE 2 is a view showing the valve of the control means.

FIGURE 3 is an end view of the valve of the control means.

FIGURE 4 is an enlarged fragmentary view of a portion of the valve and to clearly outline the shape of the valve which coacts to provide the desired position velocity.

FIGURE 5 is a partial section taken along lines 5-5 of FIGURE 4.

FIGURE 6 is a partial section taken along lines 6-5 of FIGURE 4.

FIGURE 7 is a partial section along lines 7-7 of FIGURE 4.

FIGURE 8 is a partial section taken along lines 8-8 of FIGURE 4.

FIGURE 9 is a partial section taken along lines 9--9 sin 2A As indicated hereinabove the ports of the valve included in the control means are designed to take care of the velocity relation of the piston, but it will be hereinafter.

evident to one skilled in the art that the desired velocity relation will be achieved by shaping the valve bodies such that they open or pass power fluid to the power means thru an area portional to the velocity desired of the piston.

The drawings are to be understood to be more or less of a diagrammatic character for the purpose of illustrating and disclosing a typical or preferred form of the improvements contemplated herein and in the drawings like reference characters identify the same parts in the several views. 1

Referring to the exemplaryembodiment of the invention in FIGURE 1 there is shown a variable capacity positive displacement pump comprising plural cylinders and 15', each housing plungers or pistons 16 and 16 which are reciprocated in the cylinders to pump fluid through the delivery ports 17. An intake supply is provided to the cylinders from a source through the intake ports 18. Suitable valves not shown are disposed in the valve housings 19 to regulate the inflow and outflow of the fluid to and from the cylinders 15 and 15. A variable capacity driving means 29, which is preferably awellknown variable capacity pump, is connected to the power means 21 and 21 through a control means designated I 22. Each pair of plungers 16' and 16 are disposed coaxially and on opposite sides of the power means 21 Thus the ports are shaped to obtain essentially the following relation of area to displacement:

and connected respectively to a piston 23 and 23' through shafts designated 25 and 25'.

with a plurality of admission valves 28 and 28 which selectively direct power fluid through either line 29 or 39 to chamber 31 or 32 of the power means 21 to urge the power meansto move the plungers in the desired direction. Obviously power fluid is also directed to power means 21' through lines 29 and '30; The specific function of the admission valves 28 will be described in detail Additionally, the shape of the admission valves 28 and 28' or the ports 33 and 33 will take care .of the velocity relations desired. In order to overcome the efiect that is exerted on the plungers at reversal due to unbalanced fluid valve area, static friction and inertia,

through lines 35 and 35' to selectively increase the pressure to either chamber 31 or 32 to provide the increased pressure needed to start the plunger or piston.

The operation of the valves 23 and 28 and 34, 34 are "tied respectively to the operation of the plungers 16, 16.

-More particularly valve 28 is connected to shaft 25' through levers as and 37. Valve 34' is connected to shaft 25' through levers 38 and 39.

In this fashion, it is readily apparent from the drawings that the motion of each plunger opens the valveto regulate the flow of power fluid at reversal of the plungers to the opposite power means. Accordingly, valve 28 is connected through levers 40 and 41 to shaft 25 and valve34 is connected to the shaft 25 through levers 42 and 43.

It is also apparent from the drawings that return of power fluid to the reservoir through line 44 is accomplished through conduits or lines 30 and 29 and 3t? and 29 depending on the particular direction of movement .of the piston 23 and 23'.

As was mentioned hereinabove, by providing a special shape to either the port 33, or as is shown in FIGURES 1 through 9 to the valve 28, as at 45, it is possible to regulate the admission of power fluid to either chamber 31 or 32 of the power means 21 to obtain the desired velocity for plungers .16 throughout the stroke. As long as the motion of the pistons 16 and 16' is maintained in essentially the desired relation, the motion of each piston'or plunger opens the valve to the opposite piston to an area portional to the velocity desired of the opposite piston and the total port area to the combined pistons.

Manufacturing limitations of the port shape preclude development of the valve or port shape such that the power fluid is passed to the particular power means at enough pressure to overcome the influence of the forces acting on the plunger. Specifically, in the particular arrangement wherein the control is achieved through a special shape in the valve, a lip 46 results which precludes throttling as is necessary as was mentioned above. This specific aspect is accomplished by movement of the valves 34 and 34 into or out of association'with the conduit 35 and 35' to thereby throttle (as isshown in FIGURE 1 by theposition of valve 34 relative conduit 35') flow of fluid through conduit 35. As a consequence, pressure to piston 23 is increased to provide the initial impetus to piston 16' to start the stroke of the piston in operation since piston 16' of the bottom'set shown in FIGURE 1 is at the start of the stroke.

Shaft 25 and the position of piston 16 which are at midstroke will have positioned valve 34 to throttle pressure fluid -topower means 23 and thereby increase pressure fluid flowingthrough conduit 35 through valve 28 to chamber 31 through line 30' to provide the impetus to piston 16'. As the bottom set of pistons 16'--16 move, pistons 16-16 of the top .set will be adjusting valve 34 to eliminate the throttle effect mentioned above. The opposite valves 28 and 28 will be positionedthrough their lever connections to shafts 25 and 25' to provide power fluid in accordance with the table outlined hereinabove. 5

By controlling thetfiowiof power fluid to the respective power means 23 and-23' with an arrangement of port or valve configuration it is readily apparent that the problems inherent .in prior art positive displacement plunger pumps is overcome and while a four plunger pump is-s-hown ittis readily apparent that the concepts mentioned above could be incorporated intoan arrangement .with twodouble acting pistons.

Although the invention has been described with reference to specific apparatus it will be appreciated that a :wide variety of changes may be made within the ,ability of one skilled inthe art .withoutdepartingfrom the scope of this invention. For example, some of the components of the apparatus maybe reversed, certain featuresbf the invention may be .used independently of others and equivalents may be substituted for the apparatus, all within the spirit and scope of the invention as defined in the appended claims.- a

What is .claimed is: a V V v 1. A variable capacity positive displacement pump of the reciprocating type comprising a pair of pumping cylinders each including reciprocating. plunger-like means, power means connected to each ,of the. plunger means, variable capacity regulating means for the power means totsupply power fluid to said power means at a desired pressure to cause said power means to .drive said plungerlike means to provide a desired output, conduit means connecting said variable capacity regulating means to each of said power means, a first valve means disposed in said conduit means connected to one of said power means, a second valve means disposed in the conduit connected to said other power means, both of said valve means operative to selectively pass said power fluid to said power means and to permit return of said power fluid to said variable capacity regulating means, means connecting said first valve means to one of said plunger-like means and means connecting said second valve means to sai other plunger-like means whereby both of said valve means are actuated by said plunger-like means to selectively control the flow of power fluid to both of said power means, said one plunger-like means operative to actuate said second valve means to open to permit power fluid to pass to said power means connected to said other plunger-like means and said second valve means opening to an area proportional to the velocity desired of said other plunger-like means, and said other plunger-like means operative to actuate said first valve means to open to permit power fluid to pass to said power means connected to said one plungerlike means and said first valve means opening to an area proportional to the velocity desired of said one plunger-like means.

2. A variable capacity positive displacement pump of the reciprocating type comprising a pair of pumping cylinders each including reciprocating plunger-like means, power means connected to each of the plunger means, variable capacity regulating means for the power means to supply power fluid to said power means at a desired pressure to cause said power means to drive said plungerlike means to provide a desired output, conduit means connecting said variable capacity regulating means to each of said power means, a first valve means disposed in said conduitmeans connected to one of said power means, a second valve means disposed in the conduit connected to said other power means, both of said valve means operative to selectively pass said power fluid to said power means and to permit return of said power fluid to said variable capacity regulating means, means connecting said first valve means to one of said plunger-like means and A means connecting said second valve means to said other plunger-like means whereby both of said valve means are actuated by said plunger-like means to selectively control the flow of power fluid to both of said power means, said one plunger-like means operative to actuate said second valve means to open to permit power fluid to pass to said power means connected to said other plungerlike means and said second valve means opening to an area proportional to the velocity desired of said other plunger-like means, said other plunger-like means operative to actuate said first valve means to open to permit power fluid to pass to said power means connected to said one plunger-like means and said first valve means opening to an area proportional to the velocity desired of said one plunger-like means, and a throttling means disposed in each of said conduit means and said throttling means to selectively throttle flow to one of said power means to thereby cause an increase in pressure of the power fluid being passed to said other power means.

3. The combination claimed in claim 2 wherein a second pair of plunger-like means is connected to each of the power means and each of said plunger-like means is disposed opposite to and in alignment with the plungerlike means of said first pair of plunger-like means,

4. A variable capacity positive displacement pump of the reciprocating type comprising a pair of pumping cylineach of said power means and to permit return of said power fluid to said variable capacity regulating means, actuating means connected to said valve means and op erative to actuate said valve means to selectively permit power fluid to pass to either said power means connected to one of said plunger-like means or to said power means connected to said other plunger-like means, and a throttling means connected ot said control means to selectively throttle flow to one of said power means to thereby cause an increase in pressure of the power fluid being passed to one of said power means.

5. The combination claimed in claim 4 wherein a second pair of plunger-like means is connected to the power means and each or said plunger-like means is disposed opposite to and in alignment with a plungerlike means of said first pair of plunger-like means.

6. A valve arrangement adapted for use with a variable capacity positive displacement pump of the reciprocating type comprising a pair of pumping cylinders each including reciprocating plunger-like means, power means connected to each of the plunger means, variable capacity regulating means for the power means to supply power fluid to said power means at a desired pressure to cause said power means to drive said plunger-like means to provide a desired output, conduit means connecting said variable capacity regulating means to each of said power means, said valve arrangement comprising a first valve means disposed in said conduit means connected to one of said power means, a second valve means disposed in the conduit connected to said other power means, both of said valve means operative to selectively pass said power fluid to said power means and to permit return of said power fluid to said variable capacity regulating means, means connecting said first valve means to one of said plunger-like means and means connecting said second valve means to said other plunger-like means whereby both of said valve means are actuated by said plungerlike means to selectively control the flow of power fluid to both of said power means, said one plunger-like means operative to actuate said second valve means to open to permit power fluid to pass to said power means connected to said other plunger-like means and said second valve means opening to an area proportional to the velocity desired of said other plunger-like means, and said other plunger-like means operative to actuate said first valve means to open to permit power fluid to pass to said power means connected to said one plunger-like means and said second valve means opening to an area proportional to the velocity desired of said one plunger-like means.

7. A valve arrangement adapted for use with a variable capacity positive displacement pump of the reciprocating type comprising a pair of pumping cylinders each including reciprocating plunger-like means, power means connected to each of the plunger means, variable capacity regulating means for the power means to supply power 'fluid to said power means at a desired pressure to cause said power means to drive said plunger-like means to pro vide a desired output, conduit means connecting said variable capacity regulating means to each of said power means, said valve arrangement comprising a first control means including a valve means operative to pass said power fluid to each of said power means and to permit return of said power fluid to said variable capacity regulating means, actuating means connected to said valve means and operative to actuate said valve means to selectively permit power fluid to pass to either said power means connected to one of said plunger-like means or to said power means connected to said other plunger-like means, and a throttling means connected to said control means to selectively throttle flow to one of said power means to thereby cause an increase in pressure of the power fluid being passed to one of said power means.

(References on following page) References Cited by the Examiner 3,019,735 2/62 Mueller et a1. 11;; 103-49 .UNITED STATES PATENTS 3,022,738 2/62 K-fll'te 193-49 12/38 Wolfrom et a1. 103-49 FOREIGN PATENTS 10/50 Garretson 10349 5 862,348 3/61 Great' Britain.

7/59 Bowers et al-. 60--53 1 5/60 Gerpen LAURENCE V. EFNER, Primary Examiner. 12/60 Bussche 103-49 ROBERT M. WALKER, Examiner.

Claims (1)

1. A VARIABLE CAPACITY POSITIVE DISPLACEMENT PUMP OF THE RECIPROCATING TYPE COMPRISING A PAIR OF PUMPING CYLINDERS EACH INCLUDING RECIPROCATING PLUNGER-LIKE MEANS, POWER MEANS CONNECTED TO EACH OF THE PLUNGER MEANS, VARIABLE CAPACITY REGULATING MEANS FOR THE POWER MEANS TO SUPPLY POWER FLUID TO SAID POWER MEANS AT A DESIRED PRESSURE TO CAUSE SAID POWER MEANS TO DRIVE SAID PLUNGERLIKE MEANS TO PROVIDE A DESIRED OUTPUT, CONDUIT MEANS CONNECTING SAID VARIABLE CAPACITY REGULATING MEANS TO EACH OF SAID POWER MEANS, A FIRST VALVE MEAND DISPOSED IN SAID CONDUIT MEANS CONNECTED TO ONE OF SAID POWER MEANS A SECOND VALVE MEANS DISPOSED IN THE CONDUIT CONNECTED TO SAID OTHER POWER MEANS, BOTH OF SAID VALVE MEANS OPERATIVE TO SELECTIVELY PASS SAID POWER FLUID TO SAID POWER MEANS AND TO PERMIT RETURN OF SAID POWER FLUID TO SAID VARIABLE CAPACITY REGULATING MEANS, MEANS CONNECTING SAID FIRST VALVE MEANS TO ONE OF SAID PLUNGER-LIKE MEANS AND MEANS CONNECTING SAID SECOND VALVE MEANS TO SAID OTHER PLUNGER-LIKE MEANS WHEREBY BOTH OF SAID VALVE MEANS ARE ACTUATED BY SAID PLUNGER-LIKE MEANS TO SELECTIVELY CONTROL THE FLOW OF POWER FLUID TO BOTH OF SAID POWER MEANS, SAID ONE PLUNGER-LKE MEANS OPERATIVE TO ACTUATE SAID SECOND VALVE MEANS TO OPEN TO PERMIT POWER FLUID TO PASS TO SAID POWER MEANS CONNECTED TO SAID OTHER PLUNGER-LIKE MEANS AND SAID SECOND VALVE MEANS OPENING TO AN AREA PROPORTIONAL TO THE VELOCITY DESIRED OF SAID OTHER PLUNGER-LIKE MEANS, AND SAID OTHER PLUNGER-LIKE MEANS OPERATIVE TO ACTUATE SAID FIRST VALVE MEANS TO OPEN TO PERMIT POWER FLUID TO PASS TO SAID POWER MEANS CONNECTED TO SAID ONE PLUNGER-LIKE MEANS AND SAID FIRST VALVE MEANS OPENING TO AN AREA PROPORTIONAL TO THE VELOCITY DESIRED OF SAID ONE PLUNGER-LIKE MEANS.

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