US3672794A - Injection pump - Google Patents

Abstract

A PISTON TYPE JUNCTION PUMP, HAVING MEANS FOR ADJUSTMENT OF THE VOLUME FOR EACH STROKE, BEING POWDERED SYNCHRONOUSLY BY A RECIPROCATING PUMP TO INJECT A FLUID IN A SET RATIO BY VOLUME WITH THE EFFUENT OF THE RECIPROCATING PUMP.

Description

June 27, 1972 s. REED, JR, ETAL 3,672,794

INJECTION PUMP 3 Sheets-Sheet 1 Filed Oct. 12, 1970 H l w H IF .N@ L w! i q m 0:

mm 1 QN V: o9 ON ON 0 3a. NS 3 mm. 9: WH oN NN m9 0Q 09 Q m9 om mmfl INVENTORS STNLEY E.REED,JR DONALD c. RUBY JFw. MW

ATTORNEYS June 27, 1972 s. E. REED, JR., ETAL 3,672,794

INJECTION PUMP Filed Oct. 12, 1970 3 Sheets-Sheet 2 United States Patent 01 Bee Patented June 27, 1972 3,672,794 INJECTION PUMP Stanley E. Reed, In, Haslett, and Donald C. Ruby, Lansing, Mich., assignors to FMC Corporation, San Jose,

Calif.

Filed Oct. 12, 1970, Ser. No. 79,849 Int. Cl. F04b 17/00, 35/00 (1.5. C]. 417382 3 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION The present invention relates to pumps and more particularly to means for injecting a fluid in a set ratio with the effluent of a reciprocating pump.

In many applications, such as car washes, agricultural and industrial spraying, it is desired to mix one fluid, which shall be called a solute, directly with a second fluid which shall be called a solvent, and then to spray the resulting solution without a separate mixing operation. For such applications a system employing two pumps is used. The solvent, which for most applications is Water, is pumped by the larger of the two pumps and the solute, which might be a soap, insecticide or a fertilizer, is injected into the diluent of the larger pump by a smaller pump that is keyed to the operation of the larger pump.

One system currently in use utilizes a diaphragm pump to inject the solute into the efliuent stream of a reciprocating pump to which it is connected. The diaphragm pump, however, is not entirely satisfactory for this purpose. One disadvantage of the diaphragm pump is that it has a fixed discharge rate for any given speed of the main pump and no adjustment can be made to vary the proportion of injected fluid t the etfluent of the reciprocating pump. Also, the volume discharged is dependent upon the flexibility of the diaphragm and the volume discharged by a diaphragm pump is not consistent over an extended period of use.

SUMMARY OF THE INVENTION The present invention is directed to an injection pump which, in the preferred form of the invention, is installed in one cylinder of a triplex pump for synchronous operation of the injection pump by the triplex pump. The injection pump is comprised of a tubular body with one end designed to mate in a fluid-tight seal with the cylinder of the triplex pump. A sleeve inserted in the end of the tubular body that mates with the triplex pump forms a chamber for reciprocation of a piston. The piston of the injection pump is reciprocated through one complete cycle of suction and discharge strokes for each cycle made by the triplex pump. As the piston moves through the suction stroke, fluid is drawn into the injection pump from an injection fluid supply tank. On the discharge stroke a predetermined volume of the injection fluid is injected into an effluent line from the triplex pump.

The volume of fluid injected by the injection pump during each cycle, and consequently the ratio by volume of injection fluid to triplex pump eflluent, can be adjusted as desired. Adjustment is accomplished by an adjustment hub by which an operator can manually adjust the length of the stroke of the piston of the injection pump.

Accordingly it is an object of the present invention to provide an improved means for injecting one fluid stream into another fluid stream.

Another object of the present invention is to provide a device for injecting one fluid into a second fluid in a set ratio by volume.

A further object of the present invention is to provide a. device wherein the ratio by volume of one fluid stream to be injected into a second fluid stream can be simply and accurately adjusted.

Another object of the present invention is to provide a system wherein one fluid stream is injected into a larger fluid stream, both streams being impelled by the same power source.

A still further object of the present invention is to provide a device for injecting highly corrosive fluids into the eflluent of a reciprocating pump without contaminating or fouling of the reciprocating pump.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of a spraying system embodying the present invention.

FIG. 2 is a side elevation of the injection pump operatively coupled to a triplex pump with parts being broken away for clarity.

FIG. 3 is an enlarged fragmentary central section of the injection pump.

FIG. 4 is a graphical illustration showing the discharge of the injection pump and the triplex pump as a function of the length of the injection pump stroke.

DESCRIPTION OF THE INJECTION PUMP In a preferred embodiment the apparatus of the present invention includes (FIG. 1) an injection pump or fluid metering device 10 operatively installed in one cylinder 12 (FIG. 2) of a triplex pump 14. Suitable piping connects an injection pump supply tank 16 to the injection pump 10 and connects the injection pump 10 to a discharge conduit 18 that carries the eflluent of the triplex pump 14. A spray gun 19 is attached at the end of the discharge line by means of a hose 19a. In brief, a measured amount of one fluid is drawn from the supply tank 16 and injected by the injection pump into the efiluent stream of the triplex pump.

With reference to FIG. 3 the injection pump or fluid injection device 10 comprises a generally tubular body 20, that is symmetric about axis A, a piston or reciprocable element 22 mounted for reciprocation within the body 20, a chamber 24 for pressurizing the volume of fluid to be injected, an inlet 26 to the chamber and an outlet 28 from the chamber, and a metering adjustment member or adjustable stop 30 for adjustment of the volume of fluid delivered with each stroke of the injection pump 10. More specifically the left end of the body 20 is designed to mate with the cylinder 12 (FIG. 2) of the triplex pump 14 to form a fluid-tight connection. To insure a proper fit of the injection pump 10 in the cylinder 12, the left end of the body has been machined to a diameter slightly smaller than that of the cylinder 12 and a flange 32 of larger diameter has been formed thereon for interengagement with a stepped section 34 of increased diameter at the end of the cylinder. A gasket 35 sandwiched between the flange 32 and a radially extending wall 34a of the stepped section creates a fluid-tight seal between the injection pump .10 and the cylinder 12. A pair of O-rings 36 are also installed in a groove 37 near the left end of the injection pump. When the injection pump is installed in the cylinder, the O-rings 36 are aligned with a common axis B of an intake ball check valve 12a and a discharge ball check valve 12b of the cylinder 12. The O-rings 36 serve as a bumper to limit movement of the ball of the intake valve 12a to preclude air from entering the cylinder and to reduce the noise from the valve 12a.

A cylinder or sleeve 38 is disposed within the left end of the body to form the chamber 24 for reciprocation of the piston 22. Internally the cylinder 38 is comprised of two sections, the first section 40 having a diameter D1 and the second section 42 having a larger diameter D2 and being separated from the first by a radial wall 43. A shoulder 44 near the right end of the sleeve 38 interengages a radial wall 46 of the body 20 to maintain the position of the sleeve 38 with respect to the body. A snap ring 48 installed in a groove 50 in the body 20 at the other end of the sleeve 38 holds the sleeve in this position and allows for easy removal of the sleeve from the body. The interstices between the sleeve and body are sealed against fluid leakage by an Oring S2 retained in a groove 54 in the shoulder 44 on the sleeve 38.

Referring again to FIG. 3 the piston or plunger element 22 is a solid cylindrical member comprised of an inner portion 56 of reduced diameter, a central portion 58 having a diameter that is slightly less than the diameter D1 of the first section 40 of the sleeve 38, and an outer portion 60 having a diameter that is slightly less than the diameter D2 of the second section 42 of the sleeve. The inner end 56 of the piston is internally threaded along axis A for connection to one end of the externally threaded shaft 62.

An annular packing element 64 of suitable material is installed about the reduced inner portion 56 of the piston 22 to give a fluid-tight seal between the cylinder wall 40 and the piston. The element is held in place by a washer 66 that contacts the packing element 64 and a nut 68 that tightens against the washer 66 on the threaded portion of the shaft 62. A fluid-tight seal between the piston and the cylinder is further insured by the combination of an O-ring 70 and a back-up ring 72, installed in a groove 74 in the outer portion 60 of the piston 22 to seal against leakage between the wall of the second section 42 of the sleeve and the outer portion 60 of the piston.

The shaft 62 extends (FIG. 3) through a bushing 76. threaded into a bulkhead 78 of body 20, that supports the shaft in reciprocating movement. A spring 80 that is coiled about the shaft 62 between the bulkhead 78 and the piston 22 biases the piston to the left in FIG. 3. An O-ring 82 inserted into a groove in the bushing 76 serves to seal the interstices between the shaft 62 and the bushing 76 against fluid leakage. The outer end of the shaft projects through a circular opening 84 in the adjustment member or adjustable stop 30 and is limited in movement to the left by a snap ring 86, installed in a groove on the shaft, which abuts a surface 88 of the adjustable stop 30. The stop 30 can be moved axially relative to the piston 22 to adjust the length of the stroke of the piston.

The stop 30 which infinitely adjustable, is a hollow cylindrical member having one end closed except for the circular hole 84. The adjustable stop 30 fits into the right end of the body 20 with suitable clearance for axial movement of the adjustable stop inwardly or outwardly relative to the body. A cylindrical recess at the left end (FIG. 3) of the stop 30 provides clearance for the right end of the bushing 76. An indented thread 90 having a semicircular cross section coils about the outer surface of the stop or threaded member 30 and interengages three set screws 92 (only one being shown) having oval points. The screws 92 are spaced at 120 intervals about the body. A cylindrical cap or sleeve 94, secured to the stop 30 by means of set screws 96, presents a surface which may be gripped by hand to rotate the stop 30.

The adjustable stop 30 will normally be calibrated for quick adjustments. Calibration can be simply made by a series of scribed marks on the body 20 to designate the length of the piston stroke or the volume of the chamber, or the ratio of the volume of fluid produced by the injection pump to the volume of effluent of the triplex pump with each revolution of the adjustable stop. Alignment of a leading edge 30a of the stop 30 with a scribed mark will then designate the adjusted length of the piston stroke.

The inlet 26 to the injection pump is comprised of a ball check valve 98 that is interconnected with the body of the injection pump by a section of tubing 100. The ball check valve 98, which opens during the intake stroke and which is closed during the exhaust stroke of the injection pump, consists of a cylindrical body 102 having an intake opening 104 and a discharge opening 106 and a ball 108 biased by a spring 109 to seat against the intake opening 104. The intake opening 104 is threaded for connection to a pipe 110 (FIG. 1) that extends from the injection supply tank 16. The discharge or exhaust opening 106 is threaded for connection to the section 100 of tubing that interconnects the chamber 24 of the pump. The opposite end of the tubing is threaded into an opening 112 that communicates with the chamber 24.

The outlet 28 from the injection pump comprises a short piece of tubing 114 that is threaded at one end into an opening 116 from the chamber 24 and that is threaded at its opposite end into an intake opening 118 of a ball check valve 120. The ball check valve 120, which is identical in construction to the intake ball valve, closes during the intake stroke of the injection pump and opens during the exhaust stroke. Another section 122 (FIG. 1) of tubing, which is threaded into a discharge opening 124 of the valve, interconnects the ball check valve and the discharge line 18 from the triplex pump 14.

The injection pump can be used to inject corrosive fluids into the effluent stream from the triplex pump rather than pumping a premixed solution of such fluids which would foul and corrode the triplex pump. If the injection pump is to be used to inject corrosive materials, the injection pump and its associated tubing, valves and supply tank can be made of stainless steel or other corrosion resistant material.

The triplex pump 14 of this system is similar to the pump disclosed in the US. Pat. 2,038,747 to Magnuson. The triplex pump is comprised of three in-line cylinders having piston or compression cups 126 that are disposed in the cylinders. The cups 126 are supported on rods 128 that extend from pistons 130 which are interconnected with a crankshaft 132 by means of connecting rods 134. Power is applied to the pump by a motor (not shown) which drives a countershaft 136 through a V-belt drive 138. The countershaft 136 drives the crankshaft 132 through a set of spur gears.

As stated previously the injection pump 10 is used in conjunction with the triplex pump to inject a metered amount of one fluid, such as a corrosive liquid, soap or fertilizer, into a second fluid, the effluent from the triplex pump. To perform this function, the injection pump is installed in fluid-tight engagement in one cylinder 12 of the triplex pump in place of a cylinder head and secured by a clamp 142 that encircles the outer contour of the body 20. The clamp 142 mates with a pair of threaded studs 144, that extend from the body of the triplex pump 14 and normally hold a cylinder head in place,, and is tightened against the body by clamp securing nuts 146.

The piping associated with this system includes intake conduit 148 and discharge conduit 18 for the triplex pump and the tubing that leads from the injector supply tank to the injection pump and from the injection pump to a point of injection at a T connection 150 at the end of the discharge conduit 18 from the triplex pump. The intake conduit 148 extends from an open fluid supply tank 152 to an intake orifice in the triplex pump 14. The discharge conduit 18 extends from a discharge orifice on the triplex pump to the T connection 150 and includes therebetween: a relief valve 154 which is interconnected with the triplex pump supply tank 152 by means of an overflow return conduit 155, a cutoff valve 156, an air chamber 158 to absorb pulsations and the shock caused by sudden stoppage of the flow of water in the line, and a check valve 160 to prevent the flow of injected fluid to the triplex pump supply tank.

In reference to FIG. 1 the operation of the above described spraying system including the injection pump 10 is described hereinbelow. Before commencement of normal operational use of the spraying system, an adjustment is made to the injection pump by means of the adjustable stop 30 to preset the ratio of fluid by volume produced by the injection pump as compared to the volume of eflluent of the triplex pump 14. Adjustment is made by turning the adjustable stop 30, moving the stop axially relative to the piston 22, until the leading edge 30a is aligned with a scribe mark on the body 20 that designates the desired injection pump stroke length. Once the injection pump 10 has been adjusted to deliver a desired volume of fluid as compared to the volume of eflluent of the triplex pump 14, an operator can begin a spraying operation.

With the triplex pump 14 running, the operator can control the spray by the cutoff valve 156 in the discharge line 18. And when the cutofl valve 156 is open, the injection pump operates synchronously with the triplex pump 14 to deliver a desired ratio by volume of the injected fluid to eflluent delivered by the triplex pump. That is, the injection pump makes one complete cycle for each cycle of the triplex pump. Control is also possible at the spray nozzle with a switch that would control the cutoff valve 156 by means of a solenoid.

To shut off the spray at the gun the operator will close the cutofl valve 156. The triplex pump will continue to run with the cutoff valve shut, the efiluent being diverted by the relief vlave 154 to the supply tank 152. The fluid to the injection pump is shut ed by a valve 162 in the low pressure line 110 leading from the injector supply tank 16. This valve will normally be turned off prior to the cutoff valve 156 so that any injection fluid remaining in the hose 19a and spray gun 19 are flushed with water from the pump. Flushing in this manner is especially necessary when highly corrosive fluids are injected by the injection pump.

During each cycle of the injection pump 10 a desired quantity of fluid measured by the displacement of the injection pump piston is injected into the eflluent line from the triplex pump. The compression cup 126 of the cylinder 112 of the triplex pump in which the injection pump is inserted completes one suction stroke and one discharge stroke during each cycle or revolution of the triplex pump. With each suction stroke of the compression cup 126, the piston 22 of the injection pump also undergoes a suction or intake stroke with the piston 22 being moved to the left (FIGS. 2 and 3) under the influence of the suction force created in the cylinder 12 and the bias of the spring 80. With each discharge or pressurization stroke of the compression cup 126, the piston 22 of the injection pump is urged through a discharge stroke by the pressurized column of fluid created by the discharge stroke of the compression cup 126.

The piston 22 moves to the left (FIG. 3) during the intake stroke. The length of this intake stroke is limited by the position of the adjustable stop 30. Movement of the piston 22 to the left during the intake stroke is halted as the snap ring 86 on shall 62 contacts the surface 88 of the stop 30. The discharge stroke is equal in length to the intake stroke with the piston 22 moving to the right in FIG. 3. Piston 22 is limited in movement in that direction by the radial wall 43 which serves as a fixed stop or abutment for the outer end 60 of the piston. Thus, for any given adjustment of stop 30, the piston will move through a stroke of a length determined by the adjustment of stop 30, and will therefore discharge a quantity of fluid determined by the setting of stop 30.

As the piston 22 of the injection pump 10 moves through the suction stroke, the ball check valve 98 in the inlet 26 is opened by the force of the suction, and fluid from the injection supply tank is drawn into a metering cavity comprised of the volume of the ball check valve 98, the inlet tubing 100, the outlet tubing 114 and the chamber 24 of the injection pump. The ball check valve 120 of the outlet 28 remains closed during the suction stroke. At the completion of the suction stroke, the chamber 24 of the injection pump, the tubes 100, 114 and the ball check valve 98 are filled with the injection fluid and the discharge stroke begins. With the incidence of the discharge stroke the ball check valve 98 in the inlet line closes to preclude the further entrance of injection fluid and the ball check valve in the outlet line opens as the pressure created by the discharge stroke overcomes the bias of the spring of check valve 120. During this discharge stroke a volume equal to the volume displaced by the right end of the piston 22 is impelled by the injection pump and injected into the eflluent line from the triplex pump at the T connection 150.

The injection fluid is injected under a pressure that is slightly greater than the pressure on the eflluent of the triplex pump in order to insure that the injection fluid is properly injected. The pressure of the injected fluid will always be greater than that of the triplex pump elfluent because the piston area of the injection pump is less than that of the triplex pump.

As an example of the operation of the injection pump in connection with the triplex pump consider a triplex pump having a plunger area of four (4) square inches and a plunger stroke of two (2) inches. An injection pump, identical in construction to that described above, is installed in one cylinder of the triplex pump. The injection pump of this example has a plunger area of three (3) square inches with a stroke that can be adjusted as previously related. In this example, the plunger stroke can be adjusted for any length stroke between zero (0) and two (2) inches.

The triplex pump of this example has a plunger area of four (4) square inches and a plunger stroke of two (2) inches. So the triplex pump will deliver a normal discharge per revolution, with the injection pump set for no output, of 24 cubic inches of fluid. This discharge per revolution, which is labelled V has been calculated by multiplying the plunger area of four (4) square inches by the plunger stroke of two (2) inches and then by multiplying the product of those two numbers by the number of cylinders which is three 3). Then to calculate the actual discharge volume per revolution, which is labelled V of the triplex pump with each increment of injection pump stroke, the injection pump discharge volume per revolution for each increment of injection pump stroke is substracted from the normal discharge volume per revolution V of the triplex pump. Thus the actual discharge volume per revolution V can be calculated by the formula V =V A S where A is the plunger area of the injection pump and S is the plunger stroke of the injection pump.

The graph of FIG. 4 illustrates the relationships between the volume of eflluent of the triplex pump and the volume produced by the injection pump as the stroke of the injection pump is varied over the range from zero (0) to two (2) inches in length. Curve I of this graph illustrates the normal discharge volume V per revolution of the triplex pump without the injection pump in operation. Curve II of this graph shows the actual triplex pump discharge volume per revolution V as a function of the length of the injection pump stroke. And, Curve III illustrates the discharge volume per revolution of the injection pump as a function of the injection pump stroke. The last curve on the graph, Curve IV, gives the ratio by volume of the discharge of the injection pump as compared with the discharge of the triplex pump, V /V The reciprocal (V /V of this ratio could also be plotted to give the ratio by volume of the discharge of the triplex pump to the discharge of the injection pump.

With the aid of Curve IV an operator can quickly determine the length of the injection pump stroke that is necessary to give a desired ratio by volume of injection pump discharge to triplex pump discharge. And with a simple adjustment of the adjustable stop the operator can adjust the length of the injection pump stroke 50 that the desired ratio is delivered.

Thus it can be seen that the present invention presents an injection pump that will inject one fluid into a second fluid in a set ratio by volume; that can be simply and accurately adjusted to deliver a desired ratio by volume of a first fluid to be injected into a second fluid; that can be used to inject highly corrosive fluids into the efliuent of a reciprocating pump; and that maintains the same volume ratio of injected fluid t efliuent of the reciprocating pump, which runs the injection pump, at all speeds of the reciprocating pump.

Although the best mode contemplated for carrying out the persent invention has been herein shown and described, it will be apparent that modification and variation may be made without departing from what is regarded to be the subject matter of the invention.

What is claimed is:

1. A reciprocating fluid pump comprising a plurality of first pumping cylinders each having longitudinally extending axes of generation; a first piston mounted in each cylinder for reciprocal motion along the associated axes of generation; means for driving each piston; means defining a first fluid passage including a first inlet valve and a first discharge valve for each cylinder; cylinder heads closing one end of all but one of said cylinders; and an auxiliary injection pump connected to and closing one end of said one cylinder in place of a cylinder head; said injection pump comprising an adapter housing having cylinder defining means concentric with said one cylinder and having an open end communicating with said one cylinder, a plunger disposed for reciprocation in said cylinder defining means along said axis of said one cylinder, one end of said plunger communicating directly with said one cylinder and the other end of said plunger communicating with an auxiliary pumping chamber, a second inlet valve communicating with said auxiliary pumping chamber and connected to a supply of a second fluid, a second discharge valve communicating with said auxiliary pumping chamber and with said first fluid passage means downstream of all of said first discharge valves, and resilient means urging said plunger toward the piston in said one cylinder and being coaxial with the piston in said one cylinder.

2. An apparatus according to claim 1 wherein the auxiliary pumping chamber includes a rear apertured bulkhead, and additionally comprising a shaft extending completely through said auxiliary pumping chamber and said rear bulkhead and being connected to said plunger, a seal for slidably sealing said shaft to said rear bulkhead, and adjustment means outside of said bulkhead connected to said shaft for selectively adjusting the stroke of said plunger.

3. An apparatus according to claim 1 wherein said first inlet valve associated with said one cylinder includes a movable ball in a valve seat, and wherein said cylinder defining means includes a cylindrical portion projecting into said one cylinder, a pair of resilient 0- rings on said projecting portion and disposed closely adjacent to and in alignment with said inlet valve for acting as a bumper for limiting movement and reducing the noise of the ball as it raises from its seat and for precluding air from entering the open end of said cylinder means.

References Cited UNITED STATES PATENTS 1,702,649 2/1929 Gentzen 417-382 3,450,053 6/1969 McCulloch 417-382 FOREIGN PATENTS 127,951 6/1919 Great Britain 4l7382 ROBERT M. WALKER, Primary Examiner

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