Liquid pump

Abstract: The invention relates to an improvement in reciprocable liquid pump construction to facilitate maintenance and repair of certain high-wear pump components without the necessity of removing the pump from the work site. The pump (30) has a threadable and removable cylinder (34), intake housing (36), piston (46) and ball check housings (48), and removable piston packing and glands (50), piston and inlet ball checks (47,52) and seats (54).

Description: The present invention relates to liquid pumps. In particular, it relates to an improved liquid pump construction for facilitating preventive maintenance and repairs to the pump, particularly at the job site. Liquid pumps of the type relating to this invention are typically used in industrial applications, where the pump may be installed at a location where access is limited, or where it is important to perform preventive maintenance operations or repairs without physically removing the pump from the job site. It is always desirable to be able to perform preventive maintenance or repair operations in the shortest possible time, to provide minimum interruption to the industrial activity in which the pump is associated. Liquid pumps of the general type disclosed herein are reciprocable pumps, comprising a piston reciprocable within a cylinder, with the piston connected to an external driving source via a piston or displacement rod. The cylinder typically has a lower intake valve and an upper discharge port, and the piston has a piston valve to selectively isolate the interior of the cylinder into two compartments. The lower portion of the cylinder is immersed into a liquid container, with the intake valve beneath the liquid level in the container. During the suction stroke the piston is raised within the cylinder, closing the piston valve and opening the intake valve, thereby drawing liquid into the cylinder below the piston and expelling liquid through the discharge port above the cylinder. During the pressure stroke the piston is forced downwardly within the cylinder, closing the intake valve and opening the piston valve, thereby forcing liquid in the lower portion of the cylinder beneath the piston to flow through the piston valve into the upper portion of the cylinder above the piston and outwardly through the discharge port. Documents US-A-3279376, US-A-5211611, US-A-3405606, DE-A-2214446, US-A-4089626, FR-A-740396 and FR-A-1572908 disclose various pumps of the general type discussed above. The component parts of the pump which are subject to wear are readily discernable, and it is these parts which require preventive maintenance and repair from time to time. For example, the piston packings and glands, the cylinder, the piston valve and the intake valve are all subject to relatively high wear. The need for periodic preventive maintenance of these parts is predictable, and the need for occasional repair is expected. Therefore, it is desirable to design the pump so that access to these parts can be made quickly, and without requiring disassembly of substantial portions of the pump to achieve this access. It is a principal object of the present invention to provide a pump construction which permits quick and efficient access to these component parts, particularly without requiring removal and disassembly of the entire pump to accomplish preventive maintenance and repair operations, and without the requirement of removing the entire pump from its mounting or application. It is another object of the present invention to provide a pump wherein the high-wear parts may be removed from the lower end of the pump without disengaging the pump from its driving source. It is a further object of the invention to provide a pump having a one-piece cylinder, a lower intake valve compartment, a piston and piston valve assembly, and piston packings and glands which are readily accessible for maintenance and repair. According to the present invention, there is provided a reciprocable liquid pump apparatus having: a) a pump housing (32); b) a reciprocable piston rod (40) extending through said pump housing along an axis; c) a cylinder (34) attached to said pump housing and arranged concentrically about said piston rod; d) an intake housing (36) attached to a lower end of the cylinder (34) having a passage therethrough; e) a piston (46) attached to said piston rod and having a passage therethrough along said axis; f) a piston packing and gland assembly (50) disposed about said piston; g) an inlet ball valve (38, 54, 52) attached to said intake housing for enabling fluid communication to said piston passage; and h) an outlet ball valve (48, 47) disposed between the piston and the piston rod for enabling fluid communication between the piston passage and an outlet port (44), wherein said cylinder and pump housing, said intake housing and said cylinder and said piston and said piston rod are all attached by way of a threaded attachment, characterised in that said inlet ball valve and intake housing are attached by way of a threaded attachment and said outlet ball valve is disposed between the piston and the piston rod by way of a threaded attachment, and in that said outlet port is disposed in said pump housing thereby facilitating access to parts b) through h) without moving said pump housing. In a preferred embodiment the present invention comprises a reciprocable pump having a one-piece removable cylinder with a separately-removable intake valve compartment, wherein the piston and piston valve are threadably removable from the piston displacement rod, and the piston packings and glands are threadably removable from the piston; wherein all of the foregoing components may be removed from the pump without disturbing the mounting position of the pump, or requiring removal of the pump from the job site. The piston check valve and the intake check valve can both be serviced upon removal of the intake valve compartment and the piston. All of the components are removable and accessible from the lower end of the pump without removing the piston displacement rod or disconnecting it from the driving source. The foregoing and other objects, advantages and features will become evident from the following specification and claims, and with reference to the drawings, of which:- Figure 1 shows a cross-section view of a prior art liquid pump; Figure 2 shows an elevation view of a pump of the present invention; and Figure 3 shows a cross-section view of a pump of the present invention, showing advantageous features described herein. Referring first to Figure 1, there is shown a cross-section view of a prior art pump, illustrating the features relating to assembly and disassembly of the high-wear parts in the pump. The pump 10 has a cylinder housing 12 which is affixed to a mounting bracket 14. Mounting bracket 14 may be attached to a driving motor, which is attached to a wall or floor mounting base. A discharge port 16 is attached to cylinder housing 12, providing access into the interior of the cylinder. An intake compartment 18 is threadably attached to the lower end of cylinder housing 12, and is threadably secured to clamp an intake valve assembly 20 and a cylinder sleeve 17 within the cylinder housing 12. Cylinder sleeve 17 is necessarily very tightly fitted against the interior surface of cylinder housing 12. An intake ball check 19 is movable in a chamber between a seat 13 and a ball stop 15. Piston 22 is threadably secured to piston rod 24, and piston ball check 23 is confined within a passage in the end of piston rod 24. A bolt 25 is threaded into piston rod 24 at the bottom of the passage, to provide an adjustable stop to limit the movement of ball check 23. The piston packing and gland assembly 26 is clamped between an outer shoulder 11 of piston 22 and a spacer 27, which abuts against the lower end of piston rod 24. The removal of the piston 22, piston ball check 23, packing and gland assembly 26, and cylinder sleeve 17 requires removal and disassembly of pump 10. For example, the piston 22, packing and gland assembly 26 and piston ball check 23 can only be removed by removal of piston rod 24 through the bottom of cylinder housing 12. Cylinder sleeve 17 can only be removed and replaced by disassembly of the entire pump 10, so that a removal punch can be inserted through the top opening of the cylinder housing 12 and sleeve 17 can be forced out through the bottom opening of cylinder housing 12. These operations are major maintenance operations, completely disabling the pump during the maintenance down time. Figure 2 shows an elevation view of a pump 30 constructed according to the teachings of the present invention. A pump housing 32 may be affixed to a driving motor or other suitable mounting base. A cylinder 34 is threadably attached to pump housing 32, and an intake housing 36 is threadably attached to cylinder 34. An inlet ball seat assembly 38 is threadably attached to intake housing 36. A piston rod 40 extends upwardly from pump housing 32, and is connectable to a suitable reciprocable driving source. Figure 3 shows a cross-section view of pump 30. An interior cylinder chamber 42 is formed in the space between piston rod 40 and pump housing 32 and cylinder 34, and chamber 42 communicates with an outlet passage to a discharge port 44. Cylinder 34 is preferably made from a material such as stainless steel, with an interior surface machined smoothly for guiding a piston 46. An O-ring 35 is preferably fitted about the upper end of cylinder 34 to sealably engage against pump housing 32. The lower end of cylinder 34 is threadably engaged into an intake housing 36, and an O-ring 37 is preferably fitted about the lower end of cylinder 34 to sealably engage against intake housing 36. A piston 46 is threadably attached to a ball check housing 48, and ball check housing 48 is threadably attached to the end of piston rod 40. Piston packing and gland assembly 50 is clamped between an outer shoulder of piston 46 and ball check housing 48. A piston ball check 47 is contained between piston 46 and the end of piston rod 40, to selectively open and close a passage 49 leading between the lower end of piston 46 and the interior of ball check housing 48. Four tabs 45 extend upwardly from piston 46 to confine ball check 47, with spaces between the respective tabs 45 to permit liquid flow therebetween. At least one cross passage 51 leads between the interior of ball check housing 48 and chamber 42. Therefore, liquid flow through piston passage 49 and cross passages 51 is possible when ball check 47 is raised from its seat on piston 46. The packing and gland assembly 50 is preferably made from a stacked arrangement of ring-shaped components. A male gland member 57, preferably made from stainless steel, abuts against the lower edge of ball check housing 48. A female gland member 59, preferably made from stainless steel, abuts against a lower shoulder of piston 46. A stacked arrangement of alternating layers of plastic seals 58 and leather packings 60 is clamped between male and female gland members 57 and 59. Each of the plastic seals 58 and the leather packings 60 has a V-shaped cross section, and the lower side of male gland 57 and the upper side of female gland member 59 are each complementary-shaped to engage the V-shaped cross-section. An intake ball check 52 is movable in a chamber 53 formed between seat 54 and ball stop 56. Ball stop 56 is preferably formed by casting and machining several radial ribs in intake housing 36, each rib extending inwardly sufficiently far to confine ball check 52 within chamber 53, while permitting liquid flow from the lower inlet 39 to freely pass ball check 52 by flowing through the spaces between the several radial ribs which form ball stop 56. Intake housing 36 is preferably formed of stainless steel, as is inlet ball seat assembly 38. Inlet ball seat assembly 38 is threadably attached to intake housing 36, and an O-ring 41 is sealably confined between the upper edge of ball seat assembly 38 and intake housing 36. Seat 54 is preferably made from tungsten carbide having superior wear characteristics. Inlet 39 may be threaded to receive a screen assembly or other inlet attachment, depending upon the particular application or work site configuration for pump 30. During the suction stroke of piston 46, ball check 52 is raised from seat 54, and liquid is drawn into the chambers 52 and 42 in the region within and below piston 46. Ball check 47 is held against its seat on piston 46. Liquid in the upper portion of cylinder chamber 42 (above piston 46) is forced outwardly through discharge port 44. During the pressure stroke of piston 46 the ball check 52 is held against seat 54, and ball check 47 is raised from its seat. Liquid is transferred from the lower portion of cylinder chamber 42, through passage 49 in piston 46, into the upper portion of cylinder chamber 42 via cross passages 51. Ball check 52 and seat 54 may be removed for service by threadably removing inlet ball seat assembly 38. Piston 46 may be removed for service by threadably removing cylinder 34, and then threadably removing piston 46 from ball check housing 48; packing and gland assembly 50 may be removed for service at the same time. Ball check 47 may also be removed for service by threadably removing piston 46 from the lower end of ball check housing 48. Cylinder 34 may be removed for service by threadably removing it from intake housing 36. It should be noted that all of the foregoing component parts may be removed for service without disconnecting pump housing 32 from its motor and mounting base, and without disconnecting piston rod 40 from its reciprocable drive source. Therefore, maintenance and repair of all the foregoing component parts may be accomplished while the pump 30 remains at the job site, and remains connected to its driving source and to the liquid delivery conduits connected to discharge port 44. The aforegoing description has been given by way of example only and it will be appreciated by a person skilled in the art that modifications can be made without departing from the scope of the present invention.

Claims: A reciprocable liquid pump apparatus having: a) a pump housing (32); b) a reciprocable piston rod (40) extending through said pump housing along an axis; c) a cylinder (34) attached to said pump housing and arranged concentrically about said piston rod; d) an intake housing (36) attached to a lower end of the cylinder (34) having a passage therethrough; e) a piston (46) attached to said piston rod and having a passage therethrough along said axis; f) a piston packing and gland assembly (50) disposed about said piston; g) an inlet ball valve (38, 54, 52) attached to said intake housing for enabling fluid communication to said piston passage; and h) an outlet ball valve (48, 47) disposed between the piston and the piston rod for enabling fluid communication between the piston passage and an outlet port (44), wherein said cylinder and pump housing, said intake housing and said cylinder and said piston and said piston rod are all attached by way of a threaded attachment, characterised in that said inlet ball valve and intake housing are attached by way of a threaded attachment and said outlet ball valve is disposed between the piston and the piston rod by way of a threaded attachment, and in that said outlet port is disposed in said pump housing thereby facilitating access to parts b) through h) without moving said pump housing. An apparatus as claimed in claim 1 wherein an inlet ball check (52) is provided in said intake housing (36). An apparatus as claimed in claim 2, wherein said intake housing further comprises a ball stop means (56) for limiting the movement of said inlet ball check (52) along said axis. An apparatus as claimed in any preceding claim, wherein said cylinder (34) comprises a one-piece construction made from stainless steel. An apparatus as claimed in any preceding claim, wherein a piston ball check (47) is provided in said outlet ball valve (48). An apparatus as claimed in claim 5, wherein said piston (46) further comprises a plurality of upstanding tabs (45) positioned to confine said piston ball check (47). An apparatus as claimed in any preceding claim, where said piston packing and gland assembly (50) comprises a stacked arrangement of alternating leather packing (60) and plastic seals (58), confined between an upper (57) and lower gland (59). An apparatus as claimed in claim 7, where each of said leather packing (60) and said plastic seals (58) have a V-shaped cross section, and said upper (57) and lower (59) glands have respective complementary cross sections to engage said V-shaped cross section. An apparatus as claimed in claim 8, where said upper (57) and lower (59) glands are each constructed of stainless steel material.

Inventors: HANDZEL JAMES J, HANDZEL, JAMES J.
Applicants: GRACO INC, GRACO INC.
Application year: 1995
Main classification: F04B53
IPC codes: F04B53, F04B19