US3182599A - Two-stage pump with internal washing system - Google Patents

Description

May 11, 1965 H. N. BLAKESLEE 3,182,599

TWO-STAGE PUMP WITH INTERNAL WASHING SYSTEM Filed May 27, 1963 2 Sheets-Sheet 1 Cemmfn Flan 62 m livl I ff; l2 11g 7 /ILV IIL '70 Salaam* n JNVENTOR MMA y /vELsaA/zAA/fszff B Q//mz/ ffm( y @aga WM 956eme/n* 0m* AT ToRN EYs May 11, 1965 H. N. BLAKESLEE 3,82,599

TWO-STAGE PUMP WITH INTERNAL WASHING SYSTEM Filed May 2'7, 1963 2 Sheets-Sheet 2 FIG. 2 64 99 68 j 74 FIG. 3

66 64 t 3i V V"l 164' \74 68\ y 9,94 50 Bni- 49 @9 42 y? W l INVENTUR. #Amy Nasa/v mA/aff BY Jawa@ VQ/ @ff/4Q ATTORNEYS United States Patent Oilce 3,182,599 TWG-STAGE PUMP WITH INTERNAL WASHING SYSTEM Harry Nelson Blakeslee, Barrington, Ill., assigner to American Can Company, New York, N.Y., a corporation of New Jersey Filed May 27, 1963, Ser. No. 283,391 Claims. (Cl. 103w50) This invention relates to a pump for a viscous material and more particularly it relates to a two-stage pump having capabilities of effectively transferring adhesive cement products which have a tendency to solidify within the pump thereby rendering the movable parts immovable and thus inoperative.

In fastening plastic fittings to various hardware items by means of epoxy cements, it is often necessary to apply small quantities of the cement into deep slots. Hypodermic needles have proved tobe particularly suited for introducing such small deep slots, but due to the minute orifice of the needle and the extreme viscosity of the cement, it was found that it was necessary to exert an extremely high pressure to force the cement through the orifice. This can be most easily accomplished by utilizing a pump employing the design of the present invention wherein a differential piston arrangement is provided, and in which line air pressure is applied to the large piston portion which in turn applies pressure to a smaller piston portion which exerts pressure directly upon the adhesive material. By using such a construction, the present invention provides a means whereby nominal line pressure can be magnified many times, depending upon the ratio of the cross-sectional areas of the large and small pistons.

The problem with further complicated by the fact that the cements tend to work their way up the cylinder walls while the pump is operating, and they gradually harden in place, thus freezing the pistons in place and rendering the pump inoperative. Solvents can be used to wash away unhardened cement which tends to work itself between the pistons and the cylinder walls, but such solvents cannot be allowed to combine with the cement being pumped lest it become diluted.

An object of this invention therefore is to overcome the above-mentioned problems associated with pumps for viscous adhesive products.

Another object of this invention is to provide a novel pump construction having means for internal distribution of a solvent which prevents the material being pumped from solidifying Within the pump and rendering the movable parts thereof inoperative.

A further object of the present invention is to provide a pump construction which allows internal lubrication by a solvent while preventing such a solvent from intermixing with and thus diluting the material being pumped.

Still another object of the present invention is to provide a pump which can be operated by nominal line pressure but which will discharge the material being pumped at substantially higher pressures.

A yet further object of this invention is to provide a two-stage pump which applies two separate forces to the material Ibeing pumped to thus discharge the same at increased pressures. Y

Numerous other objects and advantages of the invention will be apparent as it is better understood from the following description, which, taken in connection with the accompanying drawings, discloses a preferred embodiment thereof.

The above objects are' achieved by providing a device havinga central tube communicating between an inlet quantities of cement into such pumping such adhesive cements is f' 3,182,599 Patented May 11, 1965 and an outlet and a differential piston concentrically surrounding the tube. The differential piston includes an enlarged central disc having a stem portion extending away from each of its faces. Thus, when nominal line pressure is applied to the central disc, the stem portions magnify that pressure and apply it to the adhesive material or cement to pump the same. The cement enters the device through a check valve at the upper end 0f the central tube and accumulates in an upper annular cavity which surrounds the central tube when the piston is in the down or pump position. When the piston retracts to an up position, it applies a pressure which forces the cement from the upper annular cavity, through the central tube, past a lower check valve, and into a lower annular cavity. When the piston again moves to a down or pump position, it applies a second pressure which forces the cement from the lower annular cavity and out through a minute discharge orifice. Passages are provided for circulating a solvent between the piston and the central tube to wash away the cement which might harden and prevent piston movement. The solvent, however, is internally distributed in such a manner that it is prevented from diluting the main body of cement which is being pumped by the device.

Referring to the drawings:

FIG. l is a transverse sectional view embodiment of a pump invention;

p FIG. 2 is a fragmentary sectional view of the discharge end of the pump with the piston in a pump position; and

FIG. 3 is a fragmentary sectional view similar to FIG. 2 but with the piston in a retracted position.

As a preferred or exemplary embodiment of .the invention, FiG. l illustrates a pump generally designated 10 and comprising a hollow casing member 12 and a pair of end members 14 and 16 having stem portions 18 and 24B, respectively, extending Within said casing member. The stem 18 has internal threads 24 upper or inlet end.

of a preferred in accordance with the present on the interior of the casing 12 at its In a like manner, the stem 20 has external threads 26 which mate with internal threads 2,8 on the interior of the lower or outlet end of the casing 12. A lock nut 3@ is vthreaded onto the stem 18 and is interposed between the end member 14 and the inlet end of the casing 12, thus regulating the distance which the stem 18 extends into the ing the length of the stroke of the pump piston, in a manner which will be presently described.

A differential piston generally designated 32 is mounted within the casing 12 and is comprised of an enlarged central disc portion 3.4i and a pair of stem portions 36 and 3S, preferably extending normally from the faces of the disc 34. The stem 36 extends toward the inlet end of the pump and partially Vinto a Vbore 40 which extends completely through the end member `14. The stem 38 extends toward the outlet end of the pump and into a bore 42 which extends partially through the end member 16. An annular O-ring, or other suitable sealing means d4, seals the interface between the edge of the disc 34 and the interior walls of the casing 12. `In a like manner, an annular O-ring 46 seals the interface between the stem 35 and the bore (if) and annular O-rings 48 and `Stir Vseal the interface between the stem 38 and the bore 42.

A raised shoulder 52 exten-ds inward beyond the end of the end member stem portion 2t? to provide a seat for one face of the centr-al disc 34 of the piston. The other face of the disc 34 seats against the bottom end of the end member stem portion 18. Thus, the effective distance between the innermost ends of the stem 18 and the shoulder 52 determines the stroke of the piston 32. Since the distance the stem portion 13 extends into the casing 12 external threads 22 which mate With.

casing and thus also determin-l can be threadably adjusted by means of the lock nut 3f), the stroke can be varied accordingly.

The bore 40 is provided with threads 53 at its upper end to accommodate a plug 54 having a stem 56 with threads 58 which mate with the bore threads 53 to mount the plug. A bore 60, partially threaded at 62, extends through the plug 54. Within the bore 60, one end of an elongated central tube 64 is suitably attached, as by shrink fitting or the like. A central bore 66 extends axially through the -tube 64. The tube itself projects into and through an axial bore 68 extending through the piston 32. An annular O-ring 70 surrounds the lower end of the tube 64 to seal the interface between the lower end of the tube and the piston bore 68. Additionally, an annular O-ring 72 mounted within the upper end of the piston bore 68 serves to seal the interface between the central tube 64 and the upper end of the piston 32.

An inlet fitting 74 having an internal bore '76 is mounted at the upper or inlet end of the pump and is adapted to be suitably connected to a source of adhesive or cementitious material which is to be introduced into the pump. The fitting 74 includes a threaded stem 78 which screws into the threaded bore 62 of the plug 54. An inlet check valve is mounted between the lower end of the stem 7S and the upper end of the central tube 64, and while the check valve can be of any suitable conventional construction, it is illustrated as a spherical ball element 80 and a coil compression spring S2. The ball seats against a valve seat 84 formed in the lower end of the stem 78.

An outlet check valve assembly is provided at the lower end of the central tube 64, and is mounted at the base of the end member bore 42. The outlet check valve is comprised of a spherical ball element 86, a coil compression spring S8, and a sleeve or collar 90 having a plurality of apertures 92 therein. The collar 90 confines the ball and spring to a linear movement without limiting the fluid flow of the material. The ball 86 seats against a valve seat 94 formed in the lower end of the central tube 64.

A slender discharge passage 96 communicates with the bore 42 from beneath the outlet check valve. The end member 16 can be provided with a lower threaded stem portion 98 to which can be mounted a suitable fiow directing assembly such as the hypodermic needle previously mentioned.

The casing 12 is provided with a pair of apertures 100 and 102 on opposite sides of the piston central disc 34. Line pressure, such as air pressure or the like, is introduced through a selector valve 104 to one or the other of the casing apertures to thus move the piston either to an up or retract position or to a down or pump position. It can be seen that when air is introduced through the aperture 100 and the piston 32 moves to a down position, an upper annular cavity 106 is formed within the upper end member bore 40 between the upper end of the piston stem 36 and the lower end of the end member stem 56. When air is introduced through the aperture 102 to move the piston 32 to an up position, the upper cavity 106 is filled by the piston and a lower annular cavity 108 (FIG. 3) is formed within the lower end member bore 42 beneath the end of the piston stem 38. The line pressure thus serves as a piston driving means.

In operation, cementitious material is introduced into the pump through the inlet fitting 74, and it flows past the upper check valve and fills the bore 66 of the central tube 64. When the piston is in the down position, as shown in FIG. 1, this incoming material will also flow into and fill the upper annular cavity 106 by virtue of the provision of at least one, but preferably a plurality of slots or openings 110 in the portion of the central tube 64 which` is surrounded by the cavity 106. When line pressure is introduced through the easing aperture 102 and applied to lower face of the enlarged piston disc 34, the piston raises and the end of the upper piston stern 36, by virtue of its small area in comparison to the area of the central disc 34, applies a magnified pressure to the cement within the upper cavity 106, thus forcing this cement back through the openings 110 and through the bore 66 of the central tube 64.

At this point, the piston will have moved to the position illustrated in FIG. 3, and a lower annular cavity 10S will have been created. Due to the increased pressure resulting from the expulsion of the cement from the upper cavity 166, the lower check valve will open as shown, and cement will fill the sleeve and will flow through the apertures 92 therein to fill the lower cavity 108. Because of the narrowness of the discharge passage 96, and the high viscosity of the cement material, very little, if any, of the cement will flow through the discharge passage 96. However, when line pressure is introduced through the casing aperture to move the piston 32 to `a down or pump position, the lower piston stem 33 will exert a high pressure on the cement within the cavity 168 to cause that cement, as well as some of the cement within the interior of the sleeve 90, to be discharged through the passage 96 at extremely high pressure.

When the line pressure is again introduced through the casing aperture 102, the piston 32 raises again and the foregoing cycle is repeated. It can thus be seen that the pump of the present invention actually has two separate pressure stages, the first of which is applied to cement in the upper cavity to fill the lower cavity, and the second of which is applied to cement in the lower cavity to discharge the same.

The constant reciprocating movement of the piston 32 tends to cause a small amount of the cement being pumped to work its way between the outside of the central tube 64 and the piston bore 68. If this cement were allowed to remain trapped therein, it would harden-with some cernents quite rapidly-and prevent the piston from moving, thus rendering the pump inoperative. To prevent this from occurring, a solvent distribution system is provided. The system includes an inlet passage 112 in the end member 16 which supplies solvent to an enlarged port 114 in communication with the end member bore 42. An inlet port 116 in the piston stem 38 is juxtaposed to the enlarged port 114 for permitting the solvent to be introduced into the interior of the piston 32. An outlet port 113 is provided on the piston stem 36 for exhausting the solvent from the piston 32. Between the ports 116 and 118, the piston bore 68 is enlarged slightly to provide a narrow annular cavity 120 in which the solvent can circulate to wash the exterior of the central tube 64 and the interior of the piston 32. The spent solvent passes out the outlet port 118 into an enlarged port 122 and from there through an outlet passage 124 in the end member 14. The enlarged ports 114 and 122 ensure that solvent will continually flow to the cavity 120 regardless of whether the piston 32 is in the up position, the down position, or any position therebetween. The solvent itself is supplied to the pump from a reservoir (not shown) by any suitable means such as a conventional positive displacement pump. The spent solvent can be filtered or otherwise purified, if desired, to permit it to be returned to the reservoir to be recirculated.

As was aforementioned, it is important that the solvent be prevented from mixing with the cement being pumped and thus diluting the same. Such mixing is prevented by the use of sealing rings adjacent each end of the annular cavity 126. The sealing ring 70 on the lower end of the central tube 64 is located just below the inlet port 116 to provide an effective seal between the central tube 64 and the piston bore 68 and thus prevent downward solvent leakage. Similarly, the sealing ring 72 in the upper end' of the piston stern 36 is located just above the outlet port 118 to prevent upward solvent leakage. It is thus seen that the solvent liow is confined to the annular cavity 120 and the solvent is thus prevented from contacting the cement being pumped.

The material contemplated for use with the pump of the present invention has been alternately referred to as a cement or an adhesive and, while other high viscosity materials could be pumped by the device described herein, the preferred materials are those high viscosity twocomponent, `short pot-life reactive organic adhesives which generally comprise a mixture o-f an epoxy resin and an amine or amide resin. An example of such an adhesive is that described in United States Patent No. 2,986,539, issued to L. E. Schniepp et al. A solvent suitable for use with an epoxy two-component adhesive is methyl ethyl ketone.

It is thought that the invention and many of its attendant features will be understood from the foregoing description, and it will be apparent that various changes may be made in the form, construction and arrangement of parts without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the form hereinbefore described being merely a preferred embodiment thereof.

I claim:

1. A two-stage pump for viscous material comprising a casing; an end member assembly mounted at each end of said casing and having an aperture therein, one of said apertures deiining an inlet and the other of said apertures dening an outlet; valve means at said inlet and outlet; a central tube extending between said end member assemblies and having an axial bore which directs the flow of material between said inlet and said outlet; a piston concentrically surrounding said central tube; said piston being movable to a pump position in which it is at the end of its stroke in the outlet direction, and also being movable to a retracted position in which it is at the end of its stroke in the inlet direction; a first cavity being formed between said inlet end member assembly and said piston when said piston is in its pump position; said central tube having lateral passage means therein in the region of said Iirst cavity to permit iiow between said axial bore and said first cavity; a second cavity being formed below the outlet end of said central tube between said outlet end member assembly and said piston when said piston is in its retracted position; and means for selectively moving said piston to a pump position whereat material from said inlet will I'ill said iirst cavity and simultaneously material from said second cavity will be discharged under pressure through said outlet; said means also selectively operable for moving said piston to a retracted position whereat material from said lirst cavity will be forced under pressure into said central tube axial bore andsimultaneously material from said central tube axial bore will be forced under pressure into said second cavity.

2. A pump as delined in cla-im 1 wherein said valve means includes a ball check valve located at each end of said central tube.

3. A pump as defined in claim 1 wherein said end member assemblies are adjustable axially of said pump to vary the stroke of said piston.

4. A pump as delined in claim 1 wherein said piston is a dilferential piston having an enlarged central disc which receives the pressure from said selective moving means and transmits it to the smaller piston portions which extend into said cavities.

5. A pump as deiined in claim 1 but further characterized by an annular passage between the interior of said piston and the exterior of said central tube and means for circulating solvent through said annular passage while preventing such solvent from intermixing with and diluting the material being pumped.

6. Apparatus for pumping a viscous adhesive material comprising: -a hollow casing having an inlet end and an outlet end; valve means adjacent said inlet and outlet ends; an inlet end member mounted at the inlet end of the casing, having an aperture extending therethrough adapted to communicate with a source of material to be pumped, and having a stem portion extending into said casing; an outlet end member mounted at the outlet end of the casing, having an aperture extending partially therethrough and terminating into a discharge passage, and having a stem portion extending into said casing; a differential piston within said casing having an enlarged central disc reciprocable between the innermost ends of said stem portions and having a pair of reduced portions extending into the apertures in said end members; said piston also having a central bore extending axially therethrough; means mounting a central tube within said inlet end member aperture; said central tube extending substantially through said piston central bore, having at least one lateral opening therein adjacent to said mounting means to provide for communication between :said inlet end member aperture and the interior of said central tube, and terminating short of the terminus of said outlet end member aperture; a iirst cavity being formed between one of said piston reduced portions and said central tube mounting means when said piston central disc contacts said outlet end member; a second cavity being formed between the other of said piston reduced portions and the terminus of said outlet end member aperture when said piston central disc contacts said inlet end member; selective piston drive means `operable to move the one piston reduced portion into said first cavity to force the adhesive material therein through said central tube lateral opening and into the interior of said central tube while simultaneously forcing some adhesive material out of the intube lateral opening; and a solvent distribution system for continuously passing solvent between the exterior of `said central tube and the interior of said piston to prevent any of the adhesive material from hardening therein; said solvent distribution system including means -to prevent any of said solvent from intermixing with and diluting the adhesive material being pumped.

7. Apparatus as defined in claim 6 wherein said solvent distribution system comprises a passageway in each of said end members for providing and removing said solvent, a passageway in each of said piston reduced portions communicating with said end member passageways, and an enlarged portion of sald piston central bore between said piston passageways to thus provide an annular cavity surrounding said central tube in which the solvent can continually wash the exterior of said central tube and the interior of said piston.

8. Apparatus as defined in claim 7 wherein the means for preventing the solvent from intermixing with and diluting the adhesive material being pumped comprises sealing means between said central tube and said piston bore at each end of said annular cavity.

9. Apparatus as dened in claim 6 wherein said valve means includes an inlet ball check valve at the inlet end of said central tube and an outlet ball check valve at the outlet end of said central tube.

10. Apparatus as defined in claim 6 wherein at least one of said end members is axially adjustable to permit the stroke of said piston to be varied.

References Cited by the Examiner UNITED STATES PATENTS LAURENCE V. EFNER, Primary Examiner. ROBERT M. WALKER, Examiner.

Claims (1)

1. A TWO-STAGE PUMP FOR VISCOUS MATERIAL COMPRISING A CASING; AN END MEMBER ASSEMBLY MOUNTED AT EACH END OF SAID CASING AND HAVING AN APERTURE THEREIN, ONE OF SAID APERTURE DEFINING AN INLET AND THE OTHER OF SAID APERTURES DEFINING AN OUTLET; VALVE MEANS AT SAID INLET AND OUTLET; A CENTRAL TUBE EXTENDING BETWEEN SAID END MEMBER ASSEMBLIES AND HAVING AN AXIAL BORE WHICH DIRECTS THE FLOW OF MATERIAL BETWEEN SAID INLET AND SAID OUTLET; A PISTON CONCENTRICALLY SURROUNDING SAID CENTRAL TUBE; SAID PISTON BEING MOVABLE TO A PUMP POSITION IN WHICH IT IS AT THE END OF ITS STROKE IN THE OUTLET DIRECTION, AND ALSO BEING MOVAABLE TO A RETRACTED POSITION IN WHICH IT IS THE END OF ITS STROKE IN THE INLET DIRECTION; A FIRST CAVITY BEING FORMED BETWEEN SAID INELT END MEMBER ASSEMBLY AND SAID PISTON WHEN SAID PISTON IS IN ITS PUMP POSITION; SAID CENTRAL TUBE HAVING LATERAL PASSAGE MEANS THEREIN IN THE REGION OF SAID FIRST CAVITY TO PERMIT FLOW BETWEEN SAID AXIAL BORE AND SAID FIRST CAVITY; A SECOND CAVITY BEING FORMED BELOW THE OUTLET END OF SAID CENTRAL TUBE BETWEEN SAID OUTLET AND MEMBER ASSEMBLY AND SAID PISTON WHEN SAID PISTON IS IN ITS RETRACTED POSITION; AND MEANS FOR SELECTIVELY MOVING SAID PISTON TO A PUMP POSITION WHEREAT MATERIAL FROM SAID INLET WILL FILL SAID FIRST CAVITY AND SIMULTANEOUSLY MATERIAL FROM SAID SECOND CAVITY WILL BE DISCHARGED UNDER PRESSURE THROUGH SAID OUTLET; SAID MEANS ALSO SELECTIVELY OPERABLE FOR MOVING SAID PISTON TO A RETRACTED POSITION WHEREAT MATERIAL FROM SAID FIRST CAVITY WILL BE FORCED UNDER PRESSURE INTO SAID CENTRAL TUBE AXIAL BORE AND SIMULTANEOUSLY MATERIAL FROM SAID CENTRAL TUBE AXIALLY BORE WILL BE FORCED UNDER PRESSURE INTO SAID SECOND CAVITY.

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