US3904325A

US3904325A - Expeller pump

Info

Publication number: US3904325A
Application number: US444850A
Authority: US
Inventors: Sigfrid M Olofsson; Chester H Wickenberg
Original assignee: UPD IND Inc
Current assignee: UPD IND Inc
Priority date: 1974-02-22
Filing date: 1974-02-22
Publication date: 1975-09-09
Anticipated expiration: 1992-09-09

Abstract

A double acting expeller pump including an elongated hollow cylinder having a closure adjacent one end of the cylinder and inlet means communicating with the inside of the cylinder, with the closure having a bore extending therethrough. The pump has a piston received inside the cylinder for reciprocation therein, with the piston separating at least a portion of the inside of the cylinder into a first chamber intermediate the piston and the other end of the cylinder and a second chamber intermediate the piston and the closure. A hollow piston rod is slidably received in the closure bore, with the piston rod having one end connected to the piston and the other end extending out of the cylinder. Gate means is provided for establishing communication between the first chamber and the inlet means and closing the second chamber when the piston is moved toward the closure by the piston rod, and for establishing communication between the second chamber and the inlet means and closing the first chamber when the piston is moved toward the other end of the cylinder. The pump has valve means carried by the piston for establishing communication between the inside of the piston rod and the first chamber when the piston is moved toward the other end of the cylinder, and for establishing communication between the inside of the piston rod and the second chamber when the piston is moved toward the closure, in order that fluid is pumped from the inlet means through the piston rod and out of the pump when the piston is reciprocated in the cylinder.

Description

United States Patent [191 Olofsson et al.

[ l EXPELLER PUMP [75] Inventors: Sigfrid M. Ol01'sson, Munkedal,

Sweden; Chester H. Wickenberg, Elgin, Ill.

[73'] Assignee: UPD Industries, Inc., Chicago, Ill. [22] Filed: Feb. 22, 1974 [21] App]. No.: 444,850

Primary ExaminerWilliam L. Freeh Assistant ExaminerRichard E. Gluck Attorney, Agent, or Firm-Roy E. Petherbridge; Robert L. Lindgren', Edward D. Gilhooly [57] ABSTRACT A double acting expeller pump including an elongated [451 Sept. 9, 1975 hollow cylinder having a closure adjacent one end of the cylinder and inlet means communicating with the inside of the cylinder, with the closure having a bore extending therethrough. The pump has a piston received inside the cylinder for reciprocation therein, with the piston separating at least a portion of the inside of the cylinder into a first chamber intermediate the piston and the other end of the cylinder and a second chamber intermediate the piston and the closure. A hollow piston rod is slidably received in the closure bore, with the piston rod having one end connected to the piston and the other end extending out of the cylinder. Gate means is provided for establishing communication between the first chamber and the inlet means and closing the second chamber when the pis ton is moved toward the closure by the piston rod, and for establishing communication between the second chamber and the inlet means and closing the first chamber when the piston is moved toward the other end of the cylinder. The pump has valve means carried by the piston for establishing communication between the inside of the piston rod and the first chamber when the piston is moved toward the other end of the cylinder, and for establishing communication between the inside of the piston rod and the second chamber when the piston is moved toward the closure, in order that fluid is pumped from the inlet means through the piston rod and out of the pump when the piston is reciprocated in the cylinder.

20 Claims, 4 Drawing Figures PATENTEDSEP 9i975 3,904,325

SHEET 2 BF 2 EXPELLER PUMP BACKGROUND OF THE INVENTION The present invention relates to pumps, and more particularly to expeller pumps. 1

An assortment of hand pumps have been proposed which pump fluid for various purposes, such as bilge pumps which are useful in removing undesired water from a boat. Although such pumps may accomplish the result for which they are intended, it has been found desirable to often have a hand pump which ejects liquid, such as water, under a relatively high pressure. The liquid which is expelled from such a pump defines a farreaching trajectory and is deposited at considerable distance from the location where it is pumped. Thus, the expeller pump may be utilized to pump water for extinguishing fires, and is particularly useful on a boat where it also may be utilized as a bilge pump.

SUMMARY OF THE INVENTION A principle feature of the present invention is the provision of a hand pump of simplified construction which expels liquid under relatively high pressure.

The pump of the present invention includes an elongated hollow cylinder having a closure adjacent one end of the cylinder and inlet means communicating with the inside of the cylinder, with the closure having a bore extending therethrough. The pump has a piston received inside the cylinder for reciprocation therein, with the piston separating at least a portion of the inside of the cylinder into a first chamber intermediate the piston and the other end of the cylinder and a second chamber intermediate the piston and the closure. The hollow piston rod is slidably received in the closure bore, with the piston rod having one and connected to the piston and the other end extending out of the cylin dcr. Gate means is provided for establishing communication between the first chamber and the inlet means and closing the second chamber when the piston is moved toward the closure by the piston rod, and for establishing communication between the second chamher and the inlet means and closing the first chamber when the piston is moved toward the other end of the cylinder. The pump has valve means carried by the piston for establishing communication between the inside of the piston rod and the first chamber when the piston is moved toward the other end of the cylinder, and for establishing communication between the inside of the piston rod and the second chamber when the piston is moved toward the closure.

A feature of the present invention is that the gate means permits filling of the first chamber from the inlet means when the piston is moved toward said closure.

Another feature of the invention is that fluid is pumped from the closed first chamber through the piston and piston rod out of the pump when the piston is moved toward the other end of the cylinder.

A further feature of the invention is that the gate means permits filling of the second chamber from the inlet means when the piston is moved toward the other end of the cylinder.

A further feature of the invention is that fluid is pumped from the closed second chamber through the piston and piston rod out of the pump when the piston is moved toward the closure.

Thus, a feature of the present invention is that fluid is pumped from both chambers and expelled from the pump under relatively high pressure irrespective of which direction the piston is moved in the cylinder.

. Further features will become more fully apparent in the following description of the embodiments of this invention and from the appended claims.

DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a fragmentary sectional view of the pump of the present invention, illustrating the configuration of the pump during an inward stroke of a piston in the FIG. 2 is a sectional view of the pump of FIG. I, illustrating the configuration of the pump during an outward stroke of the piston;

FIG. 3 is a perspective view of a portion of the piston in the pump of FIGS. 1 and 2; and

FIG. 4 is a sectional view taken substantially as indicated along the line 4-4 of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIGS. I and 2, there is shown a high pressure expeller pump, generally designated I0, having an elongated hollow cylinder 12. The cylinder 12 has a closure 14 adjacent one end 16 of the cylinder and a nozzle or conduit 18 secured to the other end 20 of the cylinder, such as by threads, as shown. The closure 14 has a bore 22 extending therethrough, and the nozzle 18 defines inlet means 24 communicating with the inside of the cylinder 12 for passage of fluid through the nozzle I8 into the cylinder.

The pump 10 has a circular flexible base member 26 supported adjacent the other end 20 of the cylinder 12. The outside diameter of the base member 26 is less than the inside diameter of the cylinder 12, and the space between the base member 26 and the inside of the cylinder I2 defines passage means 27 communicating between the inside of the cylinder and the inlet means 24. The base member 26 may be supported in the cylinder by an annular screen 28 which filters debris from fluid passing from the inlet means 24 through the passage means 27 into the inside of the cylinder. The base member 26 has an annular, outwardly directed, flexible flange 30 and a cylindrical flange 32 directed toward the closure 14, the purposes for which will be described below.

The pump 10 has an elongated tubular section or gate means 34 received in the cylinder 12. The tubular section or gate 34 has an outside diameter less than the inside diameter of the cylinder and has a length less than the distance between the closure 14 and base member 26, with the spacing between the gate 34 and cylinder 12 defining channel means 37. The gate 34 is movable between a first position with one end 36 en gaged against the base member 26 and the other end 38 spaced from the closure 14, as shown in FIG. I, and a second position with the other end 38 of the gate 34 engaged against the closure 14 and the one end 36 of the gate spaced from the base member 26, as shown in FIG. 2. The gate 34 includes an annular curled extension 40 to sealingly engage against the base member 26 when the gate 34 is in its first position, as shown in FIG. 1. The closure 14 has a flexible sealing member 42 on the inside of the cylinder 12 to sealingly engage against the other end 38 of the gage 34 when the gate is in its second position, as shown in FIG. 2. The sealing member 42 has flexible flange means 44 which sealingly engage against the outside of an elongated hollow piston rod 46 to prevent passage of fluid between the inside and the outside of the cylinder between the flange means and piston rod.

The piston rod 46 is slidably received in the bore 22 of the closure 14, and has one end 47 received in the cylinder 12 and connected to a piston 48, and has its other end 50 extending out of the cylinder. The piston rod 46 defines a passageway 52 extending from the piston 48 to the outside of the pump 10, and has an outer sleeve 54 adjacent its other end 50 to facilitate manipulation of the piston rod 46 in reciprocating the piston 48 in the cylinder 12.

The piston 48 is received for reciprocation inside the gate 34, and separates the inside of the gate into a first chamber 56 intermediate the piston 48 and base member 26 and a second chamber 58 intermediate the piston 48 and the closure 14. As best illustrated in FIG. 3. the piston 48 includes an end member 60 having a first outwardly directed flange 62 and a plurality of vanes 64 projecting from a central portion of the end member 60. The first flange 62 has a plurality of apertures or first aperture means 66 extending through the first flange, with the apertures being disposed around the flange intermediate its periphery and central portion. The vanes 64 of the end member 60 are received in the passage 52 of the piston rod 46 at its one end 47, as shown in FIGS. 1 and 2, such that the first flange 62 faces toward the first chamber 56.

As shown in FIGS. 1. 2, and 4, the piston 48 also includes an annular second flange 68 which is mounted on the end member 60 adjacent the one end 47 of the piston rod 46. The second flange 68 faces toward the second chamber 58, and has a plurality of apertures or second aperture means 70 extending through the second flange 68, with the apertures 70 being disposed around the second flange intermediate its periphery and central portion. As illustrated in FIGS. 1 and 2, the first and

second flanges

62 and 68 are spaced from each other to define a space 72 between the flanges, and the vanes 64 of the end member 60 define opening means 74 communicating between the space 72 and the inside of the piston rod 46. The peripheries of the first and

second flanges

62 and 68 are spaced slightly from the inside of the gate 34 to permit movement of the piston 48 inside the gate. The first aperture means 66 of the first flange 62 communicates between the first chamber 56 and the space 72, whereas the second aperturc means 70 of the second flange 68 communicates between the second chamber 58 and the space 72. The end member 60 also has a cylindrical flange 76 directed toward the base member 26, which abuts against the cylindrical flange 32 of the base member 26 to prevent damage to the base member or piston 48 when the piston engages the base member.

An annular flexible valve element 78 is slidably received on the piston 48 in its space 72 between the first and

second flanges

62 and 68. The valve element 78 has an outer diameter such that it fr'ctionally engages against and seals with the inside of the gate 34. Thus, the valve element 78 moves between and separately en gages against the first and second flanges when the piston is moved in opposite directions in the gate 34. It is noted that the spacing between the first and

second flanges

62 and 68 is sufficiently large, the thickness of the valve element 78 is sufficiently small, and the length of the opening means 74 is sufiiciently large to prevent blockage of the opening means 74 by the valve element as the valve element slides on the piston 48.

In operation of the pump 10, when the piston 48 is moved toward the base member 26, as shown in FIG. I, the valve element 78 engages against and urges the gate 34 into sealing engagement with the outwardly directed flange 30 of the base member 26 to close the first chamber. In addition, friction between the valve element 78 and the gate 34, as well as pressure from the first chamber 56, causes the valve element 78 to seat against the second flange 68 of the piston 48 to close and seal the second aperture means 70. As shown, the valve element 78 in this position is spaced from the first aperture means 66 of the first flange 62. Accordingly, with the valve element 78 and the gate 34 in this configuration, as the piston 48 moves toward the base member 26, fluid is forced from the first chamber 56 through the first aperture means 66 and opening means 74 into the passageway 52 of the piston rod 46 and out of the pump under relatively high pressure, as indicated by the direction of the arrows in FIG. 1. Further, as indicated by the arrows in FIG. 1, fluid is withdrawn from the inlet means 24 through the channel means 37 and the spacing between the other end 38 of the gate 34 and the closure [4 into the second chamber 58 to fill the second chamber. This configuration of the pump, in pumping fluid from the first chamber 56 and filling the second chamber 58, continues until the piston 48 engages against the base member 26.

When the piston 48 is moved toward the closure 14, as illustrated in FIG. 2, the valve element 78 slides from the second flange 68 to the first flange 62 due to the friction between the valve element 78 and the gate 34, as well as pressure exerted against the valve element 78 from the second chamber 58. Accordingly, the valve element 78 seats against the first flange 62 to seal and close the first aperture means 66. At the same time, valve element 78 engages and urges the gate 34 into sealing engagement with the sealing member 42 of closure 14 to close the second chamber, and, in this position of the gate, the one end 36 of the gate 34 is spaced from the base member 26. In this configuration of the pump. the valve element 78 is spaced from the second flange 68, and fluid is pumped through the second aperture means 70, the opening means 74, the passageway 52 of the piston rod 46 and out of the pump under relatively high pressure as indicated by the direction of the arrows in FIG. 2. As also indicated by the arrows in FIG. 2, as the piston 48 moves toward the closure I4 fluid is withdrawn from the inlet means 24 through the spacing between the one end 36 of the gate 34 and the base member 26 into the first chamber 56 to fill the first chamber. This configuration of the pump, in pumping fluid from the second chamber 58 and filling the first chamber 56, continues until the piston 48 engages against the closure 14, after which the piston is again moved in the opposite direction.

Thus, fluid is pumped from the inlet means 24 and expelled from the piston rod 46 under a relatively high pressure irrespective of the direction in which the pisten 48 is moved in the pump. During operation of the pump, the gate or gate means 34 serves to establish communication between the first chamber 56 and the inlet means 24 and to close the second chamber 58 when the piston 48 is moved toward the closure 14. The gate means 34 also serves to establish communication between the second chamber 58 and the inlet means 24 and to close the first chamber 56 when the piston 48 is moved toward the base member 26. In ad dition, the valve element or valve means 78 carried by the piston 48 serves to establish communication between the inside of the piston rod 46 and the first chamber 56 when the piston is moved toward the base member 26. The valve means also serves to establish communication between the inside of the piston rod and the second chamber 58 when the piston is moved toward the closure 14.

As noted above. the pump of the present invention ejects liquid from the other end 50 of the piston rod 46 irrespective of which direction the piston is being moved inside the cylinder. The force of the ejected stream of liquid is such that the liquid is cast a considerable distance from the pump 10, and the steam ofliquid may be utilized for such purposes as extinguishing fires. It is apparent that the pump of the present invention may also be utilized as a bilge pump, or swabbing ship decks, as well as a fire extinguisher.

The foregoing detailed description is given for clearness of understanding only, and no unnecessary limitations should be understood therefrom as modifications will be obvious to those skilled in the art.

What is claimed is:

l. A double acting expeller pump. comprising:

an elongated hollow cylinder having a closure adjacent one end of the cylinder. with said closure having a bore extending therethrough;

inlet means communicating with the inside of the other end of the cylinder;

passage means communicating between the inlet means and the inside of the cylinder;

a piston received inside the cylinder for reciprocation therein. said piston separating at least a portion of the inside of the cylinder into a first chamber intermediate the piston and the other end of the cylinder and a second chamber intermediate the piston and said closure;

a hollow piston rod slidably received in the closure bore. said piston rod having one end connected to said piston and the other end extending out of the cylinder;

a base member located adjacent the other end of the cylinder, said base member being spaced from the inside of the cylinder, with the spacing between the base member and the cylinder defining said passage means;

a screen extending between the base member and the inner wall of the cylinder to support the base member and to filter debris from fluid passing from the inlet means to the inside of the cylinder;

gate means for establishing communication between the first chamber and the inlet means and closing the second chamber from communication with the inlet means when the piston is moved toward said closure by the piston rod, and for establishing communication between the second chamber from communication with the inlet means and the inlet means and closing the first chamber when the piston is moved toward the other end of the cylinder; and

valve means carried by the piston for establishing communication between the inside of the piston rod and the first chamber when the piston is moved towards the other end of the cylinder, and for establishing communication between the inside of the piston rod and the second chamber when the piston is moved toward said closure, whereby fluid is pumped from the inlet means through the piston rod and out of the pump when the piston is reciprocated in the cylinder.

2. The pump of claim I wherein said inlet means comprises a conduit secured to the other end of the cylinderv 3. The pump of claim 1 wherein said closure includes flexible flange means engaging against the outside of the piston rod to prevent passage of fluid between the inside and outside of the cylinder.

4. The pump of claim 1 including a sleeve on the outside of the piston rod adjacent its other end to facilitate manipulation of the piston rod in reciprocating said piston.

5. The pump of claim 1 wherein said piston com prises a pair of longitudinally spaced flanges adjacent the one end of the piston rod, said flanges being di rected outwardly from the piston rod toward the cylinder. said piston having opening means communicating between the inside ofthe piston rod and the spacing between the flangcs. and each of said flanges having aperture means extending through the flanges and communicating between said chambers and the spacing between the flanges.

6. The pump of claim 5 wherein the aperture means in each of said flanges comprises a plurality of apertures extending through the flanges and being disposed around the flanges intermediate the periphery and cen tral portion of the flanges.

7. The pump of claim 5 wherein the piston valve means comprises a flexible annular member slidably received on the piston intermediate the flanges, said annular member separately seating against each of said flanges to cover and seal the associated aperture means in the flanges.

8. The pump of claim 7 wherein the spacing between the flanges is sufficiently large. the thickness of the annular member is sufficiently small and the length of the opening means is sufficiently large to prevent blockage of the opening means by the annular member as the annular member slides on said piston.

9. A double acting cxpeller pump, comprising:

inlet means communicating between the inside and outside of the cylinder;

a base member adjacent the other end of the cylinder;

an elongated tubular gate received in the cylinder and having an outside diameter less than the inside diameter of the cylinder and a length less than the distance between said closure and base member, with the spacing between the gate and cylinder defining channel mcans communicating with said inlet means. said gate being movable between a first position with one end of the gate sealingly engaged against the base member and the other end of the gate spaced from said closure, and a second position with the other end of the gate sealingly engaged agaist said closure and the one end of the gate spaced from the base member;

a hollow piston rod slidably received in the closure bore, said piston rod having one end received in the cylinder and the other end extending out of the cylinder;

a piston received inside said gate and connected to the piston rod adjacent its one end for reciprocation of the piston in the gate by movement of the piston rod, said piston having first and second longitudinally spaced flanges directed outwardly from the piston rod toward said gate, said flanges separating the inside of the gate into a first chamber intermediate the first flange and said base member and a second chamber intermediate the second flange and said closure, said piston having opening means communicating between the inside of the piston rod and the spacing between said flanges, said first flange having first aperture means communicating between the first chamber and the spacing between said flanges, and said second flange having second aperture means communicat ing between the second chamber and the spacing between said flanges; and

an annular flexible valve element slidably received on the piston between said flanges, said valve element frictionally engaging against and sealing with the inside of said gate, with said valve element sealing against the second flange when the piston is moved toward the base member to close the second aper turc means and prevent passage of fluid between the second chamber and piston rod, with the valve element opening the first aperture means to permit passage of fluid from the first chamber to the piston rod through said opening means, and with the valve element engaging and urging the gate against the base member, whereby fluid is pumped from the first chamber through the piston rod and out of the pump, and fluid is received in the second chamber from the inlet means through the spacing between the gate and closure, and said valve element sealing against the first flange when the piston is moved toward said closure to close the first aperture means and prevent passage of fluid between the first chamber and piston rod, with the valve ele ment opening the second aperture means to permit passage of fluid from the second chamber to the piston rod through said opening means, and with the valve element engaging and urging the gate against the closure, whereby fluid is pumped from the second chamber through the piston to the piston rod and out of the pump, and fluid is received in the first chamber from the inlet means through the spacing between the gate and base member.

10. The pump of claim 9 wherein the inlet means communicates with the other end of said cylinder, and including passage means intermediate the base member and the cylinder communicating between the inlet means and channel means.

11. A double acting expeller pump, comprising:

an elongated hollow cylinder having a closure adjacent one end of the cylinder, with said closure having a bore extending therethrough;

inlet means communicating with the inside of the cylinder;

a piston received inside the cylinder for reciprocation therein, said piston separating at least a portion of the inside of the cylinder into a first chamber im mediate the piston and the other end of the cylinder and a second chamber intermediate the piston and said closure;

a hollow piston rod slidably received in the closure bore, said piston rod having one end connected to said piston and the other end extending out of the cylinder;

a base member located adjacent the other end of the cylinder;

gate means for establishing communication between the first chamber and the inlet means and closing the second chamber from communication with the inlet meants when the piston is moved toward said closure by the piston rod, and for establishing communication between the second chamber and the inlet means and closing the first chamber from communication with the inlet means when the pis ton is moved toward the other end of the cylinder;

said gate means comprising an elongated tubular section received in said cylinder and surrounding the piston, with the length of the tubular section being less than the distance between the closure and base member, the outer diameter of the tubular section being less than the inside diameter of the cylinder to define channel means between the tubular section and cylinder, said tubular section being movable responsive to the movement of the piston between 21 first position with one end of the tubular section engaged against the base member and the other end of the section spaced from the closure, and a second position with the other end of the tubular section engaged against the closure and the one end of the section spaced from the base member; and

valve means carried by the piston for establishing communication between the inside of the piston rod and the first chamber when the piston is moved towards the other end of the cylinder, and for establishing communication between the inside of the piston rod and the second chamber when the piston is moved towards said closure, where by fluid is pumped from the inlet means through the piston rod and out of the pump when the piston is reciprocated in the cylinder.

12. The pump of claim 11 wherein said tubular sec tion includes an annular extension adjacent its one end to sealingly engage against the base member.

13. The pump of claim ll wherein said closure includes a flexible sealing member on the inside of the cylinder to sealingly engage against the other end of the tubular section.

14. The pump of claim ll wherein the piston comprises a pair of longitudinally spaced first and second flanges adjacent the one end of the piston rod, said first and second flanges being directed outwardly from the piston rod toward the tubular section and facing said first and second chambers, respectively, said piston having opening means communicating between the in side of the piston rod and the space between said flanges, and each of said flanges having aperture means extending through the flanges.

15. The pump of claim 14 wherein the piston valve means comprises a flexible annular member slidably received on the piston intermediate the flanges and frictionally engaging the inside of said tubular section, said annular member seating against the first flange when the piston is moved toward said closure, with the annular member closing the aperture means in the first flange to prevent passage of fluid between the first chamber and the piston rod, with the annular member being spaced from the second flange to permit passage of fluid between the second chamber and the piston rod through said opening means, and with the annular member engaging and urging the tubular section toward said closure, and said annular member seating against the second flange when the piston is moved toward the base member, with the annular member closing the aperture means in the second flange to prevent passage of fluid between the second chamber and the piston rod, with the annular member being spaced from the first flange to permit passage of fluid between the first chamber and the piston rod through said opening means, and with the annular member engaging and urging the tubular section toward the base member.

16. The pump of claim wherein said first and second flanges are spaced slightly from the inside of the tubular section.

17. The pump of claim 1] wherein said valve means comprises an annular member slidahly received for longitudinal movement on said piston, said annular member frictionally engaging the inside of the tubular section to urge the tubular section in the direction of movement of said piston.

18. In a double acting expeller pump provided with a hollow cylinder having a closure adjacent one end of the cylinder, a piston received inside the cylinder for reciprocation therein, the piston separating the cylinder in the first and second chambers, inlet means communicating with the inside of the cylinder, a hollow piston rod having one end connected to the piston and the other end extending out of the cylinder, a base member located adjacent the other end of the cylinder, passages formed through the piston providing open communication with the hollow piston rod and the chambers, and valve means carried by the piston for selectively sealing one of the chambers against open communication with the piston rod and simultaneously permitting open communication with the other chamber, wherein the improvement comprises:

gate means for establishing communication between the first chamber and the inlet means and closing the second chamber from communication with the inlet means when the piston is moved toward said closure by the piston rod, and for establishing communication between the second chamber and the inlet means and closing the first chamber from communication with the inlet means when the piston is moved toward the other end of the cylinder; and

said gate means comprising an elgonated tubular section received in said cylinder and surrounding the piston, the length of the tubular section being less than the distance between the closure and the base member, the outer diameter of tubular section being less than the inside diameter of the cylinder to define channel means between the tubular section and the cylinder, said tubular section being movable responsive to the movement of the piston between a first position with one end of the tubular section engaged against the base member and the other end of the section spaced from the closure, and a second position with the other end of the tubular section engaged against the closure and the one end of the section spaced from the base member.

19. In a pump as claimed in claim 18, wherein said tubular section includes an annular extension adjacent its one end to sealingly engage against the base member.

20. In a pump as claimed in claim [8, wherein said closure includes a flexible scaling member on the inside of the cylinder to scalingly engage against the other end of the tubular section.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,904,325 Dated September 9, 1975 Sigfrid M. Olofsson et al.

Inventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 6, line 65, "agaist" should read against Column 7, line 34, after "the", first occurrence insert piston to the Column 8, line 10, "meants" should read means Signed and Sealed this twenty-seventh D ay of April 1 9 76 [SEAL] A ttes r.-

RUTH C. MASON C. MARSHALL DANN Arresting Officer (mnnu'sxium-r oj'luu'ms and Trademarks

Claims

1. A double acting expeller pump, comprising: an elongated hollow cylinder having a closure adjacent one end of the cylinder, with said closure having a bore extending therethrough; inlet means communicating with the inside of the other end of the cylinder; passage means communicating between the inlet means and the inside of the cylinder; a piston received inside the cylinder for reciprocation therein, said piston separating at least a portion of the inside of the cylinder into a first chamber intermediate the piston and the other end of the cylinder and a second chamber intermediate the piston and said closure; a hollow piston rod slidably received in the closure bore, said piston rod having one end connected to said piston and the other end extending out of the cylinder; a base member located adjacent the other end of the cylinder, said base member being spaced from the inside of the cylinder, with the spacing between the base member and the cylinder defining said passage means; a screen extending between the base member and the inner wall of the cylinder to support the base member and to filter debris from fluid passing from the inlet means to the inside of the cylinder; gate means for establishing communication between the first chamber and the inlet means and closing the second chamber from communication with the inlet means when the piston is moved toward said closure by the piston rod, and for establishing communication between the second chamber from communication with the inlet means and the inlet means and closing the first chamber when the piston is moved toward the other end of the cylinder; and valve means carried by the piston for establishing communication between the inside of the piston rod and the first chamber when the piston is moved towards the other end of the cylinder, and for establishing communication between the inside of the piston rod and the second chamber when the piston is moved toward said closure, whereby fluid is pumped from the inlet means through the piston rod and out of the pump when the piston is reciprocated in the cylinder.

2. The pump of claim 1 wherein said inlet means comprises a conduit secured to the other end of the cylinder.

3. The pump of claim 1 wherein said closure includes flexible flange means engaging against the outside of the piston rod to prevent passage of fluid between the inside and outside of the cylinder.

5. The pump of claim 1 wherein said piston comprises a pair of longitudinally spaced flanges adjacent the one end of the piston rod, said flanges being directed outwardly from the piston rod toward the cylinder, said piston having opening means communIcating between the inside of the piston rod and the spacing between the flanges, and each of said flanges having aperture means extending through the flanges and communicating between said chambers and the spacing between the flanges.

6. The pump of claim 5 wherein the aperture means in each of said flanges comprises a plurality of apertures extending through the flanges and being disposed around the flanges intermediate the periphery and central portion of the flanges.

8. The pump of claim 7 wherein the spacing between the flanges is sufficiently large, the thickness of the annular member is sufficiently small and the length of the opening means is sufficiently large to prevent blockage of the opening means by the annular member as the annular member slides on said piston.

9. A double acting expeller pump, comprising: an elongated hollow cylinder having a closure adjacent one end of the cylinder, with said closure having a bore extending therethrough; inlet means communicating between the inside and outside of the cylinder; a base member adjacent the other end of the cylinder; an elongated tubular gate received in the cylinder and having an outside diameter less than the inside diameter of the cylinder and a length less than the distance between said closure and base member, with the spacing between the gate and cylinder defining channel means communicating with said inlet means, said gate being movable between a first position with one end of the gate sealingly engaged against the base member and the other end of the gate spaced from said closure, and a second position with the other end of the gate sealingly engaged agaist said closure and the one end of the gate spaced from the base member; a hollow piston rod slidably received in the closure bore, said piston rod having one end received in the cylinder and the other end extending out of the cylinder; a piston received inside said gate and connected to the piston rod adjacent its one end for reciprocation of the piston in the gate by movement of the piston rod, said piston having first and second longitudinally spaced flanges directed outwardly from the piston rod toward said gate, said flanges separating the inside of the gate into a first chamber intermediate the first flange and said base member and a second chamber intermediate the second flange and said closure, said piston having opening means communicating between the inside of the piston rod and the spacing between said flanges, said first flange having first aperture means communicating between the first chamber and the spacing between said flanges, and said second flange having second aperture means communicating between the second chamber and the spacing between said flanges; and an annular flexible valve element slidably received on the piston between said flanges, said valve element frictionally engaging against and sealing with the inside of said gate, with said valve element sealing against the second flange when the piston is moved toward the base member to close the second aperture means and prevent passage of fluid between the second chamber and piston rod, with the valve element opening the first aperture means to permit passage of fluid from the first chamber to the piston rod through said opening means, and with the valve element engaging and urging the gate against the base member, whereby fluid is pumped from the first chamber through the piston rod and out of the pump, and fluid is received in the second chamber from the inlet means through the spacing between the gate and closure, and said valve element sealing against the first flange when the piston is moved toward said closure to close the first aperture means and prevent passage of fluid between the first chamber and piston rod, with the valve element opening the second aperture means to permit passage of fluid from the second chamber to the piston rod through said opening means, and with the valve element engaging and urging the gate against the closure, whereby fluid is pumped from the second chamber through the piston to the piston rod and out of the pump, and fluid is received in the first chamber from the inlet means through the spacing between the gate and base member.

11. A double acting expeller pump, comprising: an elongated hollow cylinder having a closure adjacent one end of the cylinder, with said closure having a bore extending therethrough; inlet means communicating with the inside of the cylinder; a piston received inside the cylinder for reciprocation therein, said piston separating at least a portion of the inside of the cylinder into a first chamber immediate the piston and the other end of the cylinder and a second chamber intermediate the piston and said closure; a hollow piston rod slidably received in the closure bore, said piston rod having one end connected to said piston and the other end extending out of the cylinder; a base member located adjacent the other end of the cylinder; gate means for establishing communication between the first chamber and the inlet means and closing the second chamber from communication with the inlet meants when the piston is moved toward said closure by the piston rod, and for establishing communication between the second chamber and the inlet means and closing the first chamber from communication with the inlet means when the piston is moved toward the other end of the cylinder; said gate means comprising an elongated tubular section received in said cylinder and surrounding the piston, with the length of the tubular section being less than the distance between the closure and base member, the outer diameter of the tubular section being less than the inside diameter of the cylinder to define channel means between the tubular section and cylinder, said tubular section being movable responsive to the movement of the piston between a first position with one end of the tubular section engaged against the base member and the other end of the section spaced from the closure, and a second position with the other end of the tubular section engaged against the closure and the one end of the section spaced from the base member; and valve means carried by the piston for establishing communication between the inside of the piston rod and the first chamber when the piston is moved towards the other end of the cylinder, and for establishing communication between the inside of the piston rod and the second chamber when the piston is moved towards said closure, whereby fluid is pumped from the inlet means through the piston rod and out of the pump when the piston is reciprocated in the cylinder.

12. The pump of claim 11 wherein said tubular section includes an annular extension adjacent its one end to sealingly engage against the base member.

13. The pump of claim 11 wherein said closure includes a flexible sealing member on the inside of the cylinder to sealingly engage against the other end of the tubular section.

14. The pump of claim 11 wherein the piston comprises a pair of longitudinally spaced first and second flanges adjacent the one end of the piston rod, said first and second flanges being directed outwardly from the piston rod toward the tubular section and facing said first and second chambers, respectively, said piston having opening means communicating between the inside of the piston rod and the space between said flanges, and each of said flanges having aperture means extending through the flanges.

16. The pump of claim 15 wherein said first and second flanges are spaced slightly from the inside of the tubular section.

17. The pump of claim 11 wherein said valve means comprises an annular member slidably received for longitudinal movement on said piston, said annular member frictionally engaging the inside of the tubular section to urge the tubular section in the direction of movement of said piston.

18. In a double acting expeller pump provided with a hollow cylinder having a closure adjacent one end of the cylinder, a piston received inside the cylinder for reciprocation therein, the piston separating the cylinder in the first and second chambers, inlet means communicating with the inside of the cylinder, a hollow piston rod having one end connected to the piston and the other end extending out of the cylinder, a base member located adjacent the other end of the cylinder, passages formed through the piston providing open communication with the hollow piston rod and the chambers, and valve means carried by the piston for selectively sealing one of the chambers against open communication with the piston rod and simultaneously permitting open communication with the other chamber, wherein the improvement comprises: gate means for establishing communication between the first chamber and the inlet means and closing the second chamber from communication with the inlet means when the piston is moved toward said closure by the piston rod, and for establishing communication between the second chamber and the inlet means and closing the first chamber from communication with the inlet means when the piston is moved toward the other end of the cylinder; and said gate means comprising an elgonated tubular section received in said cylinder and surrounding the piston, the length of the tubular section being less than the distance between the closure and the base member, the outer diameter of tubular section being less than the inside diameter of the cylinder to define channel means between the tubular section and the cylinder, said tubular section being movable responsive to the movement of the piston between a first position with one end of the tubular section engaged against the base member and the other end of the section spaced from the closure, and a second position with the other end of the tubular section engaged against the closure and the one end of the section spaced from the base member.

20. In a pump as claimed in claim 18, wherein said closure includes a flexible sealing member on the inside of the cylinder to sealingly engage against the other end of the tubular section.