US3747478A

US3747478A - Liquid sealing means for a high pressure pump

Info

Publication number: US3747478A
Application number: US00142919A
Authority: US
Inventors: R Dunn; R Rasmussen
Original assignee: Lear Siegler Inc
Current assignee: Hypro LLC
Priority date: 1971-05-13
Filing date: 1971-05-13
Publication date: 1973-07-24
Anticipated expiration: 1990-07-24
Also published as: DE2222285A1

Abstract

In a high pressure pump having reciprocating pistons each mounted in a cylinder in communication with a crankcase at the lower end thereof, a tubular bearing press fit into an opening communicating the cylinder with the crankcase with the piston stem extending therethrough. The tubular bearing extends coaxial with the piston a substantial distance into the cylinder and an inverted cup-shaped member is affixed to the bottom of the cylinder to extend coaxial with and spaced radially outwardly from the tubular bearing. The parts extend axially a sufficient distance so that the lower end of the cup-shaped member always extends a substantial distance beyond the upper end of the tubular member. A weep slot is formed in the housing in communication with the opening or portion of the cylinder surrounding the upper end of the tubular bearing. Thus, liquid leaking through seals surrounding the piston is retained outside of the tubular bearing and egresses through the weep slots, rather than passing into the crankcase.

Description

United States Patent Dunn et al.

i 1 LIQUID SEALING MEANS FOR A HIGH PRESSURE PUMP [75] lnventors: Robert H. Dunn, Bethel; Robert F.

Rasmussen, Minneapolis. both of Minn.

[73] Assignee: Lear Slegler, Inc., Santa Monica,

Calif.

[22] Filed: May 13, 1971 [21] Appl. No.: 142,919

[52] US. Cl. 92/86, 92/165 51 Int. Cl. F01b 31/20 [58] Field of Search 92/86, 157, 130, 92/208, 169, 165, 168

[56] References Cited UNITED STATES PATENTS 2,365,237 12/1944 Allen 92/86 2,801,618 8/1957 Place et al. 92186 X 3,209,772 10/1965 Atkinson et al. 92/130 X 3,073,255 l/l963 Gratzmuller' 92/86 X Primary Examiner-Martin P. Schwadron Assistant Examiner-Allen M. Ostrager Attorney-Merchant & Gould [57] ABSTRACT In a high pressure pump having reciprocating pistons each mounted in a cylinder in communication with a crankcase at the lower end thereof, a tubular bearing press fit into an opening communicating the cylinder with the crankcase with the piston stem extending therethrough. The tubular bearing extends coaxial with the piston a substantial distance into the cylinder and an inverted cup-shaped, member is affixed to the bottom of the cylinder to extend coaxial with and spaced radially outwardly from the tubular bearing. The parts extend axially a sufficient distance so that the lower end of the cup-shaped member always extends a substantial distance beyond the upper end of the tubular member. A weep slot is formed in the housing in communication with the opening or portion of the cylinder surrounding the upper end of the tubular bearing. Thus, liquid leaking through seals surrounding the piston is retained outside of the tubular bearing and egresses through the weep slots, rather than passing into the crankcase.

8 Claims, 3 Drawing Figures LIQUID SEALING MEANS FOR A HIGH PRESSURE PUMP BACKGROUND OF THE INVENTION 1. Field of the Invention In the pumping art, pumps are often constructed to pump liquid which is'compatible with the materials .forming the pumping chambers of the pump but is not compatible with the drive mechanism in the crankcase. Because most seals provided between the piston and the cylinder walls are in sliding engagement with the piston, these seals eventually wear and may leak liquid therethrough before an operator is aware of the wearing. In most of these pumps changing of the seals surrounding the piston is relatively minor maintenance but, if the liquid leaks into the crankcase, the entire pump must be overhauled and cleaned, or replaced. Thus, it is essential that some means he provided for preventing the leakage of the liquid into the crankcase.

2. Description of the Prior Art In most prior art pumps, additional sealing means are provided between the piston stem, or connecting rod, and the crankcase, which sealing means includes a sliding or wiping surface in engagement with the reciprocating stem or rod. This sliding or wiping surface is also subject to wear and, unless it is checked and replaced periodically may allow leakage therethrough. Thus, the prior art means of sealing pumps to prevent leakage of liquid into the crank case simply compounds the problem since additional packing or the like must be periodically replaced and, in the event that the periodic maintenance is prolonged leakage can and will occur.

SUMMARY OF THE INVENTION I The present invention pertains to liquid sealing means for a high pressure pump wherein a tubular bearing member is sealingly engaged in an opening between the. crankcase and the cylinder with the piston stern engaged therein, the tubular member extending a substantial distance coaxially along the piston stem into the cylinder, an inverted cup-shaped member is coaxially positioned in downwardly extending relationship at the bottom of the piston so that the lower edge thereof extends a substantial distance beyond the upper edge of the tubular member and is spaced radially outwardly therefrom. A weep slot is provided in the housing in communication with the area surrounding the tubular bearing inv the cylinder so that liquid leaking from the outer surface of the cup-shaped member into the area egresses through the weep slot. Y

It is an object of the present invention .to provide an improved lower seal for high pressure pumps to prevent liquid leaking around the piston from entering the crankcase.

It is a further object of the present invention to provide an improved seal which'does not depend upon wiping or frictionally engaged sliding surfaces to prevent leakage and, therefore, is greatly improved in operating characteristics.

These and other objects of this invention will become apparent to those skilled in the art upon consideration of the accompanying specification, claims and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Referring to the drawings, wherein like characters indicate like parts throughout the figures:

FIG. 1 is a view in side elevation of a multi-piston FIG. 2 is an enlarged sectional view as seen from the line 22 in FIG. 1, illustrating the improved liquid sealing means; and

FIG. 3 is a view as seen from the line 3-3 in FIG. 2;

DESCRIPTION OF THE PREFERRED EMBODIMENT In the figures the numeral 10 generally designates a housing having a lower portion or base 11 and an upper portion vor head 12. The base 11 defines a crankcase 13 having a shaft 14 rotatably mounted therein and adapted to be driven by a motor or the like. A plurality of disks 15 are eccentrically affixed to the shaft 14 for rotation therewith and each disk 15 has a piston stem 16 (only one illustrated) associated therewith. The piston stems 16 are slidably engaged with the outer periphery of the disks l5 and reciprocate in response to rotation of the shaft 14 and disks 15.

The base 11 further defines an upwardly directed circular opening positioned to receive each of the piston stems l6 concentrically therethrough. The circular openings communciate with an elongated chamber 17 having a generally rectangular-shaped cross section and extending parallel with the crankcase 13. In the present embodiment, three openings are formed in the upper wall of the base 11 and three coaxially aligned cylindrical openings are defined in the head 12, which openings cooperate to define cylinders extending vertically upwardly from the chamber 17. In the illustrations, only one cylinder 18 is illustrated but it should be understood that the present sealing means might be utilized with pumps having any number of cylinders and a disclosure of a three-cylinder pump and the operation thereof is made in the copending application of Robert F. Rasmussen, Ser. No. 22,176, filed Mar. 24, 1970, and entitled Improved Pump.

A pumping chamber 20 and valve mechanism, generally designated 21, are illustrated at the upper end of the cylinder 18 and will not be discussed in detail since the operation thereof is standard and a typical example may be found in the above-described copending application. A,piston 22 is mounted in the cylinder 18 for reciprocating movement and packing 23 is positioned in encircling engagement therewith to form a high pressure seal and prevent the leakage of fluid from the upper portion. of the head 12 into the base 11. The packing 23 is held in place by a retainer ring 24, which is positioned in the cylinder 18 within'the head 12 and bears against the upper surface of the base 11 to maintain the packing 23 and other parts of the pump fixedly in position.

The piston 22 has an axially extending opening 30 therethrough designed to receive a bolt 31 therein. The opening 30 is designed to allow the bolt 31 to extend outwardly through the bottom of the piston 22 a short distance. An inverted cupshaped member 32 is positioned in abutting engagement with the bottom of the piston 22 so that an opening therethrough is axially aligned with the opening 30 through the piston 22. The piston stem 16 has a threaded opening formed in the upper end thereof and is threadedly engaged on the lower end of the bolt 31 to fix the piston stem 16 coaxially within the cup-shaped member 32. The cup-shaped member 32 has a radially outwardly directed flange 33 at the lower edge thereof and a compression spring-34 is positioned between the flange 33 and the lower surface of the retainer ring 24 to bias the entire assembly of the piston 22, cup-shaped member 32 and piston stem 16, downwardly into engagement with the periphery of the associated disk 15. In some embodiments the piston stem 16 will be engaged on the disk so that the compression spring 34 can be eliminated. In these embodiments the flange 33 on the cup-shaped member 32 may also be eliminated. It should be understood that the present embodiment of the cup-shaped member 32 is illustrated for simplicity and many other embodiments might be utilized to perform the functions of the present invention.

A tubular bearing memberfgenerally designated 40, is sealingly engaged in the opening between the crankcase 13 and the chamber 17. The bearing member 40 is positioned coaxial with the piston stem 16 and receives the piston stem 16 therethrough. In the present embodiment the axially extending opening through the bearing member 40 has a constant diameter throughout. The bearing member 40 extends vertically upwardly coaxial with the piston stem 16 into the chamber 17*and a substantial distance above the lower edge of the cup-shaped member 32 in all operating positions of the cup-shaped member 32. The portion of the bearingmember 40 which is engaged in the opening between the crankcase 13 and the chamber 17 is substantially larger than the outer diameter of the portion of the bearing member 40 which extends upwardly into the chamber 17. The outer diameter of the portion of the bearing member 40 extending into the chamber 17 is substantially smaller than the inner diameter of the cup-shaped member 32 so that the upper edge of the bearing member 40 is positioned within the cup-shaped member 32 and free relative movement therebetween is allowed. The juncture between the portion extending into chamber 17 with a smaller diameter and the larger diameter portion of the bearing member 40 is slanted generally downwardly and radially outwardly in a generally conically-shaped surface 41. The surface 41 extends outwardly beyond the vertical opening into the crankcase 13 to form a radially outwardly extending skirt 42. The skirt 42 overlies the junction between the housing 10 (defining the vertical opening into the crankcase l3) and the outer diameter of the bearing member 40. In the present embodiment, the bearing member 40 is press fit into the vertical opening defined by the housing 10 and a liquid sealant is utilized to sealingly engage the bearing member 40 in the opening defined by the housing 10 and prevent any leakage therebetween.

The outer diameter of the piston stem 16 is substantially smaller than the inner diameter of the bearing member 40, except for a portion 45 adjacent the lower end of the piston stem 16. The portion 45 extends axially from the lower end of the piston stem 16 a distance approximately equal to two-thirds of the axial length of the bearing member 40 and has an outer diameter slightly smaller than the inner diameter of the bearing member 40 so as to allow relative sliding movements therebetween. The portion 45 of the piston stem 16 has axially extending grooves 46 in the surface thereof to provide communication between the crankcase 13 and the chamber 17 for preventing the build-up of pressure in either the crankcase 13 or the chamber 17 during reciprocating movements of the piston 22, cup-shaped member 32 and piston stem 16. It should be understood that either the outer surface of the piston stem 16 or the inner surface of the bearing member 40 might have grooves formed therein to provide axially extending openings for communication between the crankcase l3 and the chamber 17, or other configurations may be devised by those skilled in the art to perform the functions of the present invention.

Thus, any fluid which leaks through the packing 23 and retainer ring 24 will flow along the outer surface of the cup-shaped member 32 and drop into the lower portion of the chamber 17 surrounding the bearing member 40. Since the upper edge of the bearing member 40 is positioned well above the lower edge of the cup-shaped member 32, the liquid flowing along the outer surface of the cup-shaped member 32 cannot enter the axial opening through the bearing member 40. Further, the sealing engagement of the bearing member 40 in the opening defined by the housing 10 and the overlying skirt 42 prevent the leakage of the liquid between the bearing member 40 and the housing 10. Weep holes or slots 50 are formed in the housing 10 and extend from the lowermost surface defining the chamber 17, adjacent the outer edge of the skirt 42, downwardly through the wall of the housing to the atmosphere. In the present embodiment, the weep holes 50 are positioned approximately centrally along the chamber 17 and only one weep hole 50 is provided on each side of the housing 10, but it should be understood that more or less weep holes 50 might be provided if desired. Thus, fluid leaking through the packing 23 and flowing downwardly along the outer surface of the cupshaped member 32 drops to the lower surface of the chamber 17 and egresses from the housing 10 through the weep holes 50.

An improved liquid sealing means is disclosed which prevents liquid, which leaks through the high pressure packing of the pump, from flowing into the drive mechanism of the crankcase. The sealing means does not require wiping or sliding engagement between moving parts to prevent the leakage therebetween and, thus, the sealing ability of the sealing means is not impaired by wear of the parts. Because the wear of the parts does not affect the sealing ability thereof, the life and reliability of the liquid sealing means is greatly improved. Further, maintenance and installation costs and problems are greatly reduced.

While I have shown and described a specific embodiment of this invention, further modifications and improvements will occur to those skilled in the art. I desire it to be understood, therefore, that this invention is not limited to the particular form shown and I intend in the appended claims to cover all modifications which do not depart from the spirit and scope of this invention.

What is claimed is:

1. Liquid sealing means for a high pressure pump having a housing, a cylinder formed within said housing and having a pumping chamber at one end thereof and a crankcase at the other end thereof, a reciprocating piston with a stem coupled thereto mounted in said cylinder and extending between said pumping chamber and said crankcase within said housing and with said piston stem extending between a rotating member in said crankcase and the lower end of said piston, said sealing means comprising:

a. a generally annular tubular member sealingly engaged in the housing coaxial with said piston stem, being disposed generally between the lower end of said cylinder and said crankcase and extending upwardly into said cylinder, and with at least a portion of the inner periphery of said annular tubular member operating as a bearing for the piston stem;

b. a weep slot formed in the housing in communication with the lower end of the cylinder and dis charging externally of the housing; and

c. a generally inverted cup-shaped member affixed to the lower end of the piston and movable therewith, said cup-shaped member being disposed in radially outwardly spaced coaxial relationship around said piston stem and the upwardly extending portion of said annular tubular member, said cup-shaped member extending downwardly beyond the upper end of said tubular member in all operating positions of the piston.

2. Liquid sealing means as set forth in claim 1 wherein the tubular member includes a radially outwardly extending skirt overlying the junction of the tubular member and the housing.

3. Liquid sealing means as set forth in claim 1 wherein the cup-shaped member includes a radially outwardly extending flange affixed to the outer surface thereof for receiving a compression spring in engagement therewith to bias the piston downwardly in the cylinder.

4. Liquid sealing means as set forth in claim 1 wherein the piston, cup-shaped member and piston stem are assembled into a unit by means of an axially extending bolt.

5. Liquid sealing means as set forth in claim 1 wherein the pump includes a plurality of pistons and cylinders, a transversely extending opening in the housing is in communication with and forms the lower end of each of the cylinders, and a pair of weep slots are provided, one on each side of the housing.

6. Liquid sealing means as set forth in claim 1 wherein a portion of the piston stem adjacent the lower end thereof has an outer diameter slightly smaller than the inner diameter of the tubular member and the diameter of the remainder of the stem is substantially smaller, the axial length of the portion having a larger diameter is substantially less than the axial length of the tubular member so that the bearing surface between the piston stem and the tubular member is substantially less than the overall coaxial surfaces therebetween.

7. Liquid sealing means as set forth in claim 1 wherein the piston stem has axially extending grooves in the periphery thereof adjacent the lower end to allow communication between the crankcase and the lower portion of the cylinder.

8. Liquid sealing means for a pump having a housing, a cylinder formed within said housing and having a pumping chamber at one end thereof and a crankcase at the other end thereof, a reciprocating piston with a stem coupled thereto mounted in said cylinder and extending between said pumping chamber and said crankcase within said housing, and with said piston stem extending between reciprocating means disposed in said crankcase and the lower end of said piston, said sealing means comprising:

a. a stationary generally annular tubular member sealingly engaged in said housing between said cylinder and crankcase and extending upwardly into said cylinder;

b. a weep slot formed in the housing in communication with the lower end of said cylinder and discharging externally of said housing; and

c. an inverted cup-shaped member affixed to the lower end of the piston and movable therewith, said cup-shaped member being disposed in radially outwardly spaced coaxial relationship around said piston stem and the upwardly extending portion of said annular tubular member, said cup-shaped member extending downwardly beyond the upper end of said tubular member in all operating positions of the piston.

Claims

1. Liquid sealing means for a high pressure pump having a housing, a cylinder formed within said housing and having a pumping chamber at one end thereof and a crankcase at the other end thereof, a reciprocating piston with a stem coupled thereto mounted in said cylinder and extending between said pumping chamber and said crankcase within said housing and with said piston stem extending between a rotating member in said crankcase and the lower end of said piston, said sealing means comprising: a. a generally annular tubular member sealingly engaged in the housing coaxial with said piston stem, being disposed generally between the lower end of said cylinder and said crankcase and extending upwardly into said cylinder, and with at least a portion of the inner periphery of said annular tubular member operating as a bearing for the piston stem; b. a weep slot formed in the housing in communication with the lower end of the cylinder and discharging externally of the housing; and c. a generally inverted cup-shaped member affixed to the lower end of the piston and movable therewith, said cup-shaped member being disposed in radially outwardly spaced coaxial relationship around said piston stem and the upwardly extending portion of said annular tubular member, said cup-shaped member extending downwardly beyond the upper end of said tubular member in all operating positions of the piston.

8. Liquid sealing means for a pump having a housing, a cylinder formed within said housing and having a pumping chamber at one end thereof and a crankcase at the other end thereof, a reciprocating piston with a stem coupled thereto mounted in said cylinder and extending between said pumping chamber and said crankcase within said housing, and with said piston stem extending between reciprocating means disposed in said crankcase and the lower end of said piston, said sealing means comprising: a. a stationary generally annular tubular member sealingly engaged in said housing between said cylinder and crankcase and extending upwardly into said cylinder; b. a weep slot formed in the housing in communication with the lower end of said cylinder and discharging externally of said housing; and c. an inverted cup-shaped member affixed to the lower end of the piston and movable therewith, said cup-shaped member being disposed in radially outwardly spaced coaxial relationship around said piston stem and the upwardly extending portion of said annular tubular member, said cup-shaped member extending downwardly beyond the upper end of said tubular member in all operating positions of the piston.