WO2006130837A2

WO2006130837A2 - High pressure rotary pump

Info

Publication number: WO2006130837A2
Application number: PCT/US2006/021490
Authority: WO
Inventors: Jose P. Munoz; Dieter A. Tischler
Original assignee: Kmt Waterjet Systems, Inc.
Priority date: 2005-06-02
Filing date: 2006-06-02
Publication date: 2006-12-07
Also published as: WO2006130837A3

Abstract

A rotary pump includes a rotatable shaft, a rotary drive member connected with the shaft and having an angled drive surface centered about a shaft drive axis. One or more pumping units each include a piston linearly displaceable along a pump axis, spaced from and extending parallel with the drive axis, a and having a working end for pressurizing a fluid and an opposing driven end. A coupler assembly is configured to operably couple the piston driven end with the angled drive surface such that rotation of the rotary member linearly displaces the piston along the pump axis and configured to substantially reduce sliding contact between the piston and any portion of the rotating pump component. Each piston is disposed within a bore through a drive base and a removably connected pressurizing base and is formed of drive and pressurizing portions, the pressurizing portion being separately removable from the pump.

Description

TITLE OF THE INVENTION High Pressure Rotary Pump

The present invention relates to fluid machinery, and more particularly to pumps used to pressurize fluids, such as water, to relatively high pressures.

Pumps are commonly used to move fluids from one place to another and to pressurize fluids for storage or use. Many different types of pumps are suited to pumping fluids, including reciprocating plunger pumps that employ one or more plungers that reciprocate within a bore or cylinder to move or pressurize the working fluid. In some applications, pumps capable of delivering high-pressure fluid are required. For example, water-jet cutting may require fluid that is pressurized to a working pressure in excess of 10,000 pounds per square inch. Typically, pumps for water cutting applications have generally been either intensifier pumps or direct drive crank pumps. Intensifier pumps use hydraulic fluid to actuate a piston or "plunger" that pressurizes the water, whereas direct drive pumps use a rotating drive shaft to drive one or more plungers by means of separate crank-slider mechanisms.

SUMMARY OF THE INVENTION In one aspect, the present invention is a high-pressure rotary pump comprising a shaft rotatable about a central drive axis and a rotary drive member connected with the shaft. The rotary drive member has an angled drive surface, the drive surface being generally centered about and extending at a skewed angle with respect to the drive axis. At least one pumping unit includes a piston linearly displaceable along a pump axis, the pump axis being spaced from and extending generally parallel with respect to the drive axis. The piston has a working end configured to pressurize a fluid and an opposing driven end. Further, a coupler assembly is configured to operably couple the piston driven end with the rotary member drive surface such that rotation of the rotary member linearly displaces the piston along the pump axis. The coupler assembly is further configured to at least substantially reduce sliding contact between the piston and any portion of the pump angularly displacing about the drive axis.

In another aspect, the present invention is a pumping unit for a high-pressure rotary pump, the pump having a housing, a drive shaft disposed at least partially within the housing and being rotatable about a drive axis, and a rotary drive member connected with the shaft. The pumping unit comprises a drive base coupled with the pump housing and having at least one bore providing at least a portion of a drive chamber and a pump axis extending longitudinally through bore. A pressurizing base has bore and is removably connected with the drive base such that the pressurizing base bore is coaxially aligned with the at least one drive base bore and the pump axis extends longitudinally through the pressure bore. The pressurizing base bore at least partially provides a pressure chamber. Further, a piston is disposed at least partially within the drive bore and at least partially within the pressurizing bore so as to be linearly displaceable along the pump axis. The piston includes a drive portion disposed at least partially within the drive chamber, the drive portion having a first, driven end operably engaged with the rotary drive member, a second opposing end. A pressurizing portion disposed at least partially within the pressure chamber and has a first end configured to pressurize fluid within the pressure chamber and an opposing second end connected with the drive portion second end.

In a further aspect, the present invention is again a high pressure rotary pump. The pump comprises a housing, a drive shaft disposed at least partially within the housing and being rotatable about a drive axis, and a rotary drive member connected with the shaft and having an angled drive surface. A drive base is coupled with the pump housing and has a plurality of drive bores spaced circumferentially about the drive axis. Each drive base bore provides a portion of a separate drive chamber and a plurality of pump axes each extend longitudinally through a separate one of the bores. A plurality of pressurizing bases each have a bore and is removably connectable with the drive base. As such, each pressurizing base bore is coaxially aligned with a separate one of the drive base bores such that one pump axis extends longitudinally through the pressurizing bore. Each pressurizing base bore at least partially provides a pressure chamber. Further, a plurality of pistons are each disposed at least partially within a separate one of the drive bores and at least partially within the pressurizing bore aligned with the one drive bore so as to be linearly displaceable along the associated pump axis. Each piston includes a drive portion disposed at least partially within the associated drive chamber, the drive portion having a first, driven end operably engaged with the rotary drive member, a second opposing end. Each piston also includes a pressurizing portion disposed at least partially within the associated pressure chamber, the pressurizing portion having a first end configured to pressurize fluid within the pressure chamber, an opposing second end connected with the drive portion second end. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS The foregoing summary, as well as the detailed description of the preferred embodiments of the present invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there is shown in the drawings, which are diagrammatic, embodiments that are presently preferred. It should be understood, however, that the present invention is not limited to the precise arrangements and instrumentalities shown. In the drawings:

Fig. 1 is a perspective view of a rotary pump in accordance with the present invention; Fig. 2 is an exploded view of interior portions of the pump;

Fig. 3 is an enlarged exploded view of drive shaft, rotary drive member, and bearing portions shown in Fig. 2;

Fig. 4 is an enlarged, exploded view of the rotary drive member, bearing components, transfer member and drive pin portions shown in Fig. 2; Fig. 5 is an enlarged, exploded view of the transfer member, drive pins and a coupler assembly shown in Fig.2;

Fig. 6 is an axial cross-sectional view of the pump; Fig. 7 is an enlarged view of a section 7 in Fig. 6; Fig. 8 is an enlarged view of section 8 of Fig. 6; Fig. 9 is a greatly enlarged view of section 9 of Fig. 8, showing the preferred seal structure;

Fig. 10 is a greatly enlarged view of a section of a pumping unit similar that shown in Fig. 9, but depicting an alternative seal construction;

Figs. 1 IA-I ID, collectively Fig. 11, are top plan views of the transfer member and piston driven ends, each showing the movement thereof at 90° increments of rotation of the drive member; and

Figs. 12A-12D, collectively Fig. 12, are axial cross-sectional views corresponding to each one of Figs. 1 IA-I ID, showing the tilting movement of a single transfer member cross-section in a plane Pc indicated in Figs. 1 IA-I ID.

DETAILED DESCRIPTION OF THE INVENTION Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of "including," "comprising," or "having" and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms "mounted," "connected," "supported," and "coupled" and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, "connected" and "coupled" are not restricted to physical or mechanical connections or couplings.

Referring now to the drawings in detail, wherein like numbers are used to indicate like elements throughout, there is shown in Figs. 1-12 a high pressure rotary pump 10 in accordance with the present invention, which is particularly suited for pressurizing water or other pumping fluid to very high pressures (e.g., over 10,000 psi) for "waterjet" cutting applications. The high pressure rotary pump 10 basically comprises a drive shaft 12 rotatable about a central drive axis 13, a rotary drive member 14 connected with the shaft and having an angled drive surface 15, at least one and preferably a plurality of pumping units 18 spaced circumferentially about the drive axis 13, and a coupler assembly 20 operably coupling all of the pumping units 18 with the rotary drive member 14. The pump 10 includes a housing 11, which is preferably formed of two connected, generally cylindrical body halves 11a, 1 Ib, and the drive shaft 12 has first, exterior end 12a extending from the housing 11 and a second, interior end 12b disposed within the housing 11. The shaft exterior end 12a is operably connected with a "prime mover" such as a motor or engine (neither shown), either directly or through a transmission (e.g., a gear train, belt-and-pulley device, chain-and sprocket mechanism, etc.) (none shown). The rotary drive member 14 is mounted to the drive shaft second end 12b and has drive surface 15 generally centered about and extending at a skewed angle As with respect to the drive axis 13. As such, the rotary drive member 14 functions generally similarly to a "wobble plate", as discussed in further detail below. Preferably, the rotary drive member 14 includes a generally cylindrical block 17 with a circumferential outer surface 17a and opposing first and second axial ends 17b, 17c, the first block end 17b being connected with the drive shaft 12 and the second end 17c having an angled face providing the rotary drive surface 15. Further, each pumping unit 18 includes a base 19 having a bore 21, a piston 22 disposed at least partially within the bore 21, and a pump axis 23 extending longitudinally through the bore 21. The bore 21 has a drive chamber section 25 and a pressure chamber section 27 and the piston 22 is linearly displaceable along the pump axis 23, each pump axis 23 being spaced from and extending generally parallel with respect to the drive axis 13. The pistons 22 each have a working end 24 configured to pressurize a pumping or "working" fluid, preferably water, a peroxide solution, or similar fluid suitable for "waterjet" cutting operations (discussed below), located within the pressure chamber 27, and an opposing driven end 26. Preferably, the pumping unit base(s) 19 are formed of a single drive base portion or "drive base" 19a coupled (e.g., connected or integrally formed) with the pump housing 11 and at least one and preferably a plurality of pressurizing base portions or "pressurizing bases" 19b connected with the drive base 19a. The drive base 19a has at least one and preferably a plurality of bores 43 each providing at least a portion of one drive chamber 25 and each pressurizing base 19b has a bore 45 providing at least a portion of one pressure chamber 27. When each pressurizing base 19b is connected with the drive base 19a, the pressuring bore(s) 45 are each coaxially aligned with a separate one of the drive bore(s) 43 such that the associated pump axis 23 extends longitudinally and centrally through the aligned bores 43, 45. Preferably, each pressurizing base 19b is removably connected with the drive base 19 for reasons described below, but may be fixedly connected, or even integrally formed, with the drive base/base portion 19a. Most preferably, the pump 10 includes a pressure block 29 mounted to the pump upper housing half 11a, the pressure block 29 providing the drive base 19a, and thus at least a portion of the bores 21 of all the pumping units 18, as described in detail below. Further, the coupler assembly 20 is configured to operably couple each of the piston driven ends 26 with the rotary member drive surface 15 such that rotation of the rotary member 14 linearly displaces the each piston 22 along the associated pump axis 23. Specifically, as the rotary drive member 14 rotates about the drive axis 13, preferably at speed between zero (0) and eight hundred (800) rotations per minute (rpm), a "high point" 15a and a "low point" 15b on the drive surface 15 each rotate within a separate circular path p_a, p_b (see Figs. 1 IB and 11C) about the axis 13. As such, the drive surface high and low points 15a, 15b each pass sequentially generally beneath, although preferably offset radially-outwardly from, each piston driven end 26 (see Figs. 11 and 12). When the drive surface 15 is positioned with respect to a particular piston 22 such that the piston driven end 26 is disposed against/proximal to the drive surface low point 15b, rotation of the drive member 14 causes the piston 22 to linearly displaced in a first direction I₁ along the pump axis 23, thereby advancing the working end 24 into the pressure chamber 27 to pressurize fluid therein. The piston 22 continues displacing in the first direction Ii until the drive surface high point 15a passes generally beneath the driven end 26. Thereafter, the piston 22 is displaced in a second direction I₂ along the axis 23, withdrawing the working end 24 from the pressure chamber 27 to "draw" fluid therein, until the drive surface low point 15b again passes beneath the driven end 26.

Furthermore, the coupler assembly 20 is also configured to at least substantially reduce, and preferably to almost completely prevent, sliding contact between the pistons 22 and any portion of the pump 10 that angularly displaces or rotates about the drive axis 13. Such sliding contact may cause premature wear to the piston driven ends 26 and/or generate excessive lateral loading on the pistons 22 (i.e., generally perpendicular to the pump axis 23), either of which may cause the pistons 22, particularly the radially-smaller plunger portions (described below), to fracture or otherwise fail, as discussed in further detail below. Preferably, the coupler assembly 20 includes a transfer member 28 disposed generally against the rotary member drive surface 15, most preferably indirectly through a bearing assembly 30 (described below), and each piston driven end 26 is disposed generally against the transfer member 28 to thereby operably couple the pump units 18 with the rotary drive member 14. The coupler assembly 20 is configured to at least substantially reduce angular displacement of the transfer member 28 about the drive axis

13 during rotation of the rotary drive member 14.

As such, the transfer member 28 generally oscillates about a center point Cx located generally on the drive axis 13 to linearly displace the piston along the pump axis 23, as best shown in Figs. 12A-12B. However, the transfer member 28 remains generally axially fixed with respect to the drive axis 13 (e.g., at an angle Ac); in other words, the member 28 preferably does not rotate or pivot about the axis 13 (or at least rotates at a substantially lesser speed than the drive shaft 12), to at least minimize relative motion between the transfer member 28 and the driven ends 26 of the one or more pistons 22, as indicated in Figs. 1 IA-I IB. The transfer member 28 is preferably generally "free- floating", such that member 28 is capable of angularly displacing relative to the piston driven ends 26, which can also prevent transverse or side loading (i.e., perpendicular to the pump axes 23) on the pistons 22, but is not intended to rotate with the rotary drive member

14 about the drive axis 13. Preferably, the transfer member 28 has a first, "upper" contact surface 31A facing generally toward the pumping units 18, the piston driven ends 26 each being disposed generally against the contact surface 3 IA, and an opposing second or "lower" contact surface 3 IB facing generally toward the rotary member drive surface 15. An axis 28a extends through the center point C_T and generally perpendicularly with respect to the upper surface 3 IA, such that when the transfer member 28 oscillates about the center point C_T, the surface axis 28a rotates about the drive axis 13 (as shown in Figs. 11 and 12). Further, any cross-section Sc of the transfer member 28 within a plane Pc containing the drive axis 13 (i.e., "axial" cross-sections) generally pivots or "tilts" about an axis Tc extending perpendicularly to the drive axis 13 as the rotary drive member 14 rotates about the axis 13, as depicted in Figs. 12A-12D.

More specifically, Fig. 12 depicts the motion of one randomly-selected, exemplary transfer member cross-section Sc, against which is disposed the center point of contact Cc of the driven end 26 of one selected piston Ps, as the rotary drive member 14 displaces one revolution about the drive axis 13 in a designated direction D_R, as indicated in Fig. 11. Figs. 1 IA and 12A show the rotary drive member 14 at a reference position P_R or initial angular position A_R0 (e.g., 0°), with the drive surface low point 15b being disposed generally beneath the designated piston contact point Cc. In this configuration, the selected transfer member cross-section Sc is arranged in a "downwardly-tilted" orientation about the center point C_T, such that the selected piston Ps is at lower or "bottom-stroke" position L_B along the piston axis 23. As the rotary drive member 14 angularly displaces about 90° from the initial or reference position P_R, SO as to be located at a first angular position A_RI (Fig. 1 IB), the drive surface high point 15a displaces toward the designated contact point Cc such that the transfer member cross-section Sc pivots in a first tilt direction ti about the center point C_T, or section tilt axis Tc, toward a generally "level" orientation (Fig. 12B). Such movement of the transfer member 28 causes the selected piston P₅ to displace in the first linear direction I₁ along the piston axis 23 until reaching about a "mid-stroke" position L_M (see Fig. 12B), while the contact point Cc and designated cross-section Sc remain at about the fixed angular position Ac (see Fig. 1 IB). Thereafter, the rotary drive member 14 continues angularly displacing about drive axis 13 by another 90° to a second angular position A_R2 until the drive surface high point 15a becomes disposed generally beneath the designated contact point Cc (Fig. 11C), causing the transfer member cross-section Sc to continue pivoting in the first tilt direction ti about the center point C_τ/axis Tc until becoming disposed in an "upwardly-tilted" orientation (Fig. 12C). This movement of the transfer member 28 causes the piston Ps to continue displacing in the first linear direction I₁ until reaching an upper or "top-stroke" linear position L_T (see Fig. 12C). Furthermore, continued movement of the rotary drive member 14 through another

90° to a third angular position A_R3 causes the drive surface high point 15a to move generally away from, and the drive surface low point 15b to move generally toward, the designated piston contact point Cc (Fig. 1 ID). Such drive member movement causes the transfer member cross-section Sc to pivot in a second, opposing tilt direction t₂ about the center point Gp/tilt axis Tc until again being disposed at the generally level orientation, while the selected piston Ps displaces in an opposing, second linear direction I₂ along the axis 23 until again reaching the mid-stroke position L_M (see Fig. 12D). Finally, movement of the rotary drive member 14 through another 90° returns the drive member 14 to the initial angular position A₀ (Fig. 1 IA), such that the drive surface low point 15b is again located generally beneath the designated contact point Cc (Fig. 12A). During such drive member movement, the designated transfer member cross-section Sc continues pivoting in the second tilt direction t₂ until returning to the downwardly-tilted orientation, while the selected piston Ps displaces in the second linear direction I₂ until reaching the bottom- stroke position L_B, as shown in Fig. 12 A. As discussed above and indicated in Figs. 1 IA-I ID, the designated contact point

Cc ideally remains at a generally fixed angular position Ac with respect to the drive axis 13, and thus no other points on the transfer member 28 rotatably displace about the axis 13, while the rotary drive member 14 revolves thereabout. Although some angular displacement of the transfer member 28 about the drive axis 13 may occur, such movement is significantly lesser than would be the case were the piston driven ends 26 instead disposed directly against the rotary drive surface 15, as is found with previously known "wobble plate" pumps. Further, it must be noted that the transfer member cross- section Sc and piston contact point Cc, depicted in Figs. 11 and 12, and discussed above were selected for purposes of illustration only, and that all transfer member cross-sections taken axially through the drive axis 13 behave/move in a generally identical manner as the described above.

Referring now to Figs.2-4, 6 and 7, the coupler assembly 20 preferably further includes a thrust bearing 32 disposed between the transfer member 28 and the rotary drive member 14, most preferably between the transfer member 28 and an adapter plate 34 mounted on the drive surface 15, as discussed below. The thrust bearing 32 is configured to enable the transfer member 28 to remain generally angularly fixed with respect to the drive axis 13 as the drive member 14 rotates about the axis 13. Preferably, the thrust bearing 32 includes a cage plate 36 and a plurality of rollers 38 rotatably attached to the cage plate 36 so as to be spaced circumferentially about the drive axis 13. Each roller 38 is configured to roll simultaneously generally against the transfer member surface 3 IB and against the rotary member drive surface 15, i.e., indirectly through the preferred adapter plate 34. As such, when the rotary drive member 14 rotates about the drive axis 13, the movement of the adapter plate 34 with respect to the rollers 38 cause the rollers 38 to roll upon the plate 34, thereby causing the cage plate 36 to also rotate about the axis 13, but at an angular velocity substantially lesser than that of the drive member 14. In turn, the bearing rollers 38 also roll against the transfer plate lower surface 3 IA, but such roller motion preferably causes little or no rotation of the transfer member 28 about the drive axis 13, for the reasons described above. As best shown in Figs. 3, 4 and 7, the transfer member 28, the thrust bearing 32, and the adapter plate 34 form the bearing assembly 30 as referenced above. Preferably, the transfer member 28 includes a generally circular plate 40 having a central opening 41 and the bearing assembly further includes a generally cylindrical hub 42 attached to the rotary drive member drives surface 15. The adapter plate 34 and the cage plate 36 each preferably have a central opening 35, 37, respectively, and the hub 42 extends through the aligned openings 35, 37 to mount the bearing assembly 30 onto the drive surface 15 (see Fig. 7). However, the central openings 37, 41 of the bearing cage plate 36 and transfer plate 40 each fit about the hub 42 with sufficient clearance to permit the hub 42 to rotate relative to the plates 36, 40 as the drive member 14 rotates about the drive axis 13. Referring to Figs.2, 5 and 7, the coupler assembly 20 also preferably includes a biasing subassembly 46 configured to bias the driven end 26 of each piston 22 generally toward the rotary member drive surface 15, to thereby operably couple each piston 22 with the rotary drive member 14. Preferably, the biasing subassembly 46 includes an engagement member 48 coupled with each one of the pistons 22 and a biasing member 50. The biasing member 50 is configured to bias the engagement member 48 generally toward the rotary member drive surface 15 so as to maintain the piston driven ends 26 coupled with the rotary drive member 14, preferably through the transfer member 28 as described above. Specifically, the biasing member 50 biases the engagement member 48 generally toward the transfer member 28 so as to maintain the piston driven ends 26 disposed against the transfer member upper contact surface 3 IA. Preferably, the engagement member 48 includes a generally circular plate 52 with a central opening 53 and at least one and preferably a plurality of engagement openings 54 spaced circumferentially about the plate 52. A portion of each piston 22 is disposed within a separate one of the engagement openings 54 to thereby movably couple the engagement member 48 with all of the pistons 22.

Further, the biasing subassembly 46 preferably further includes a pivot joint 56 connecting the engagement member 48 with the biasing member 50. The pivot joint 56 is configured to permit the engagement member 48 to pivot about a center point C_E on the drive axis 13 spaced from the transfer member center point C_T (see Fig. 7). As such, the engagement member 48 oscillates with the transfer member 28 to maintain the driven ends 26 of all of the pistons 22 disposed against the transfer member upper surface 3 IA, thereby ensuring that movement of the rotary drive member 14 linearly displaces the pistons 22 as described above. As best shown in Fig. 7, the pivot joint 56 preferably includes a generally cylindrical socket member 58 coupled to the engagement member 48 and having a generally spherical cavity 59 and a ball member 60 disposed at least partially within the cavity 59 and coupled with the biasing member 48. The ball member 60 preferably has a central opening 61 and the biasing subassembly 46 further includes a generally circular cylindrical post 62 attached to the pump pressure block 29, the post 62 extending through the ball central opening 61 to movably couple the pivot joint 56 with the block 29.

Furthermore, the socket member 58 is preferably disposed within the engagement plate central opening 53 and is preferably fixedly attached thereto by one or more fasteners (e.g., screws none shown), as shown in Figs. 6 and 7, or may alternatively by be movably coupled with the plate 52, such as by means of a clip 64 (see Figs. 2 and 5). In either case, linear displacement of the socket 58 causes the socket 58 push or pull the engagement member 48, such that each piston 22 is displaced along its respective axis 23. With the movable structure shown in Figs. 2 and 5, the socket member 58 is capable of angularly displacement about the drive axis 13 while the engagement member 48 remains generally at a fixed angular position with respect to the axis 13. Therefore, a torque applied to the pivot joint 56 will not be transferred through the engagement member 48 to the pistons 22. Alternatively, the socket 58 may be formed having an upper, radially smaller section 58a and a lower, radially larger portion 58b, such that an annular shoulder 58c is formed therebetween, as indicated in Fig. 7. With this structure, the upper socket section 58a extends through the engagement plate opening 53, and the engagement plate 52 is attached to the socket shoulder 58c, preferably by means of threaded fasteners (none shown), to thereby fixedly connect the engagement member 48 with the pivot joint 56. Additionally, the biasing member 50 preferably further includes a collar 66 slideably disposed upon the post 62 and a coil spring 68 disposed about the post 62. The coil spring 68 has a first end 68a disposed generally against the pressure block 29 and a second end 68b disposed generally against the collar 66, such that the spring 68 generally biases the collar 66 against the ball member 60. In turn, the socket member 58 biases the engagement plate 48, through clip 64 pushing against the plate upper surface 52a or the fixed connection between the plate 48 and the socket 58, generally toward the transfer plate 28 to maintain the piston driven ends 26 against the upper contact surface 3 IA.

Referring now to Figs. 5-8, the piston 22 of each pumping unit 18 preferably includes a drive portion 70 disposed at least partially within the associated bore drive chamber 25 and a pressurizing portion 72 disposed at least partially within the pressure chamber 27. The piston drive portion 70 has a first, driven end 70a providing the piston driven end 26, as described above, a second opposing end 70b, and a diameter D_d extending generally perpendicularly with respect to the bore axis 23. The piston pressurizing portion 72 has a first end 72a providing the piston working end 24, as described above, an opposing second end 72b connected with the drive portion second end 70b, and having a diameter Dp extending generally perpendicularly with respect to the bore axis 23. The drive portion diameter D_d is substantially larger than the pressurizing portion diameter Dp, such that the ratio of the drive diameter D_d to the pressurizing diameter Dp is preferably at least two to one (2:1), for the following reasons.

By having a diametrically larger drive portion 70, the pistons 22 are capable of supporting relatively larger lateral forces F_L (see Fig. 8), which are greatest at the unsupported lower, driven end 26 of each piston 22. Further, the pressurized fluid within each pressure chamber 27 exerts an axial force F_A on the associated piston 22, which must be supported by the thrust bearing 32 (see Fig. 8). The axial force F_A is proportional to the surface area of the working end 24 (i.e., Force = Pressure x Area), such that reducing the diameter Dp of the pressurizing portion 72 reduces the magnitude of the force F_A. Therefore, constructing each piston 22 having the drive portion 70 substantially diametrically larger than the pressurizing portion 72 provides a piston structure with sufficient lateral stiffness and which does not experience an excessive force F_A, such that the thrust bearing 32 may sized relatively smaller. In other words, by having a relatively lesser axial force F_A on each piston 22, the minimum size of the thrust bearing 32 necessary to support the pistons 22 is reduced.

Preferably, the drive portion 70 and pressurizing portion 72 of each piston 22 are two separate parts connected together in any appropriate manner. Specifically, each piston 22 preferably includes first and second generally circular cylindrical rods 74, 76 each having an outside diameter dd, dp that is substantially constant about the perimeter of the particular rod 74, 76, the drive rod diameter d_d being substantially larger than the pressurizing rod diameter dp. The first rod or "drive pin" 74 provides the drive portion 70 and has opposing ends 74a, 74b, the first end 74a including a joint ball 73 and the second end 74b having a connective cavity 75. The piston 22 further includes a contact shoe 78 with a spherical socket 79 configured to receive the drive pin ball 73, so to pivotally connect the shoe 78 with the pin 74, and a contact surface 80. The shoe contact surface 80 is disposed generally against the transfer member upper contact surface 3 IA to couple the piston 22 with the rotary drive member 14, and the shoe 78 pivots upon the ball 73 to maintain contact with the transfer member 28. Further, the piston second rod or "plunger" 76 has opposing ends 76a, 76b, the first end 76a providing the piston working end 24, as discussed below, and second end 76b having a connective head 82 sized radially larger than the rod 76. The plunger connective head 82 is receivable within the drive pin connective cavity 75, and is preferably retained therein to releasably connect the plunger 76 with the drive pin 74. By having the removably connected drive and pressurizing portions 70, 72, the one or more plungers 76 may be removed from the pump 10 for servicing or replacement without removing the associated drive pins 74 therefrom. That is, the drive ρin(s) 74 remain connected with the coupler assembly 20, as described above, while the associated plunger 76 is disengaged from the pin second end 74b and thereafter removed from the pump 10.

This feature is particularly beneficial as the plungers 76 and associated components (e.g., liner sleeves, etc.) experience much greater stresses, and are thus more likely to fail, than the drive pins 74.

Alternatively, the drive pin 74 and the plunger 76 may be fixedly connected, such as by welding or braising, or the drive portion 70 and the pressurizing portion 72 may be integrally formed, such that the piston 22 is generally of one-piece construction. Further, the drive portion 70 and/or the pressurizing portions 72 may alternatively be formed of bars or elongated members with cross-sections that are generally square, elliptical, hexagonal, etc., that have thicknesses which taper along the length thereof, or have any other desired structure which still permits the pump 10 to function generally as described herein. Furthermore, although the ratio of the drive portion diameter D_d to the pressurizing portion diameter Dp is preferably about two to one (2:1), the diameter ratio may be greater (e.g., over 3:1) or lesser (e.g., 1.1:1), or even generally equal (i.e., 1:1), as desired for a particular application.

Referring specifically to Fig. 8, the base bore 21 of each pumping unit 18 preferably has an interior surface 65 extending circumferentially about the pump axis 23 and defining at least a portion of the pressure chamber 27, which is preferably provided by a sleeve member 67. Each plunger 76 preferably has an outer circumferential surface 71 extending about the axis 23 and located at, or proximal to, the piston working end 24. Each plunger outer surface 71 is spaced radially inwardly from the associated chamber inner surface 65, such that an annular clearance passage 69 is defined between the inner and outer surfaces 71, 65. As such, a portion of the pumping fluid being pressurized by each pumping unit 18 flows axially about the sides of the plunger 76, downwardly through the pressure chamber 27, and generally toward the drive chamber 25. Because of such fluid flow, each pumping unit 18 preferably further comprises at least one seal 84 configured to prevent any fluid passing through the clearance passage 69 from entering the drive chamber 25, as described below. Although such a "seal-less" plunger 76 allowing fluid flow through the clearance passage 69 is presently preferred, the pumping units 18 may alternatively include a seal (none shown) affixed to the plunger 76 and configured to prevent fluid from flowing along the sides of the plunger 76.

Referring to Figs. 8-10, the drive chamber 25 preferably contains a quantity of a lubricant fluid (e.g., oil), for reducing friction and dissipating heat generated by the slideably displacing drive pin 74, and the pressure chamber 27 is configured to contain water, a peroxide solution, or any other preferred pumping fluid being pressurized by the plunger 76. To ensure separation of these different fluids, each pumping unit 18 also preferably includes at least one seal 84 disposed within either the drive chamber 25 or/and the pressure chamber 27 and configured to generally prevent fluid flow between the drive and pressure chambers 25, 27. Thereby, water or other pumping fluid is prevented from entering the drive chamber 25 and lubricant fluid is prevented from entering the pressure chamber 27.

In a first embodiment shown in Figs. 8 and 9, each pumping unit 18 preferably includes first and second seal members 85, 86 spaced apart along the piston axis 23. The first seal member 85 is fixedly disposed generally within the drive chamber 25 and has a central opening 85a sized to receive a portion of the drive portion 70/drive pin 74, such that the pin 74 is slidable through the fixed seal member 85. The first seal member 85 is configured to retain the lubricant fluid within the drive chamber 25. Further, the second seal member 86 is disposed generally within the pressure chamber 27 and has a central opening 86a sized to receive a portion of the pressurizing portion 72/plunger 76, such that the plunger 76 is slidable therethrough. The second seal member 86 is configured to retain water or other pumping within the pressure chamber 27, so that the pumping fluid does not enter the drive chamber 27, but is preferably drained from the lower end of the pressure chamber 27 through an appropriate drain passage (not shown). In a second embodiment shown in Fig. 10, each pumping unit preferably includes a single seal 87 disposed within either the drive chamber 25 or the pressure chamber 27 and having a central opening 88. The central opening 88 is sized to receive a portion of either the drive pin 74 or the plunger 76, depending on in which chamber 25 or 27 the seal 87 is disposed. Specifically, Fig. 10 depicts the seal 87 disposed in a lower, radially-larger section of the pressure chamber 27, such that the seal opening 88 is sized to receive the plunger 76, but may alternatively be disposed in the drive chamber 25 and sized to receive a portion of the drive pin 74. Preferably, the seal is a cartridge seal having two sealing elements 89A, 89B disposed within a cylindrical body 90, each sealing element 89A, 89B being configured to prevent fluid flow into the central opening 88 from a separate side of the body 90. However, the seal 84 may be constructed in any appropriate manner capable of preventing fluid exchange between the two bore chambers 25, 27.

Referring now to Figs. 6 and 8, as discussed above, the pump 10 preferably includes a drive base 19b provided by a pressure block 29, which is preferably generally cylindrical and has opposing interior and exterior surfaces 100, 102. The block 29 has at least one and preferably a plurality of through holes 104 extending generally between the surfaces 100, 102. Each through-hole 104 provides one drive bore 43, and thus at least a portion of the drive chamber 25, and may also provide a portion of the pressure chamber 27. Further, the pressurizing base 19b of each pumping unit 18 is preferably provided by a separate, second block 106 having a bore 108 providing the pressurizing bore 45, and thus at least a portion of the pressure chamber 27. The second blocks 106 are each connectable with the pressure block 29 such that each second block bore 108 is aligned with one of the pressure block through-holes 104 generally along the pump axis 23 of one pumping unit 18. Preferably, each second block 106 includes a cylinder 110 and a generally annular mounting flange 112 attachable to the pressure block exterior surface 102 to removably mount the cylinder 110 thereto. Further, each cylinder 110 is configured to receive a separate one of the plungers 76 so as to form the pressurizing portion of each pumping unit 18. As described above, the cylinders 110 may each be separately removed from the preferred pressure block 29 such that the cylinder 110, or/and the plunger 76 contained therein, may be serviced or replaced while the associated drive pin 74 remains engaged with the rotary drive member 14. Additionally, with the structure of a plurality of separate cylinders 110, one cylinder 110 and/or the associated plunger 76 may be removed from the drive base/pressure block 29 while the other cylinders 110 remain connected with the block 29. Further, each cylinder 110 includes a fluid port 114 and a check valve assembly

116 configured to regulate fluid flow into and out of the pressure chamber 27. Most preferably, the plungers 76, cylinders 110, check valve assemblies 116 and all related components are constructed and function as described in co-pending U.S. Patent Application Serial No. 11/111,116, entitled "Close Fit Cylinder and Plunger" the entire contents of which are incorporated by reference herein. However, the pumping units 18 may be constructed such that both the drive chamber 25 and pressure chamber 27 are of provided in a single base or base block, such at the pressure block 29, or in any other alternative appropriate manner.

It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as defined in the appended claims.

Claims

We claim:

1. A high pressure rotary pump comprising: a shaft rotatable about a central drive axis; a rotary drive member connected with the shaft and having an angled drive surface, the drive surface being generally centered about and extending at a skewed angle with respect to the drive axis; at least one pumping unit including a piston linearly displaceable along a pump axis, the pump axis being spaced from and extending generally parallel with respect to the drive axis, the piston having a working end configured to pressurize a fluid and an opposing driven end; and a coupler assembly configured to operably couple the piston driven end with the rotary member drive surface such that rotation of the rotary member linearly displaces the piston along the pump axis and configured to at least substantially reduce sliding contact between the piston and any portion of the pump angularly displacing about the drive axis.

2. The rotary pump as recited in claim 1 wherein the coupler assembly includes a transfer member disposed generally against the rotary member drive surface, the piston driven end being disposed generally against the transfer member, the coupler assembly being configured to at least substantially reduce angular displacement of the transfer member about the drive axis during rotation of the rotary drive member such that the transfer member generally oscillates about a center point located generally on the drive axis to linearly displace the piston along the pump axis while at least minimizing relative motion between the transfer member and the piston driven end.

3. The rotary pump as recited in claim 2 wherein the transfer member has an upper contact surface, the piston driven end being disposed against the contact surface, and an axis extending through the center point and generally perpendicularly with respect to the upper surface, the transfer member axis rotating about the drive axis as the transfer member oscillates about the center point.

4. The rotary pump as claim 2 wherein the coupler assembly is configured such that any cross-section of the transfer member within a plane containing the drive axis generally pivots about an axis extending perpendicular to the drive axis as the rotary drive member rotates about the axis.

5. The rotary pump as recited in claim 2 wherein the coupler assembly includes a thrust bearing disposed between the transfer member and the rotary drive member and configured to enable the transfer member to remain generally angularly fixed with respect to the drive axis as the drive member rotates about the axis.

6. The rotary pump as recite in claim 5 wherein: the transfer plate has a surface facing generally toward the rotary member drive surface; and the thrust bearing includes a cage plate and a plurality of rollers rotatably attached to the cage plate so as to be spaced circumferentially about the drive axis, each roller being configured to roll simultaneously generally against the transfer member surface and against the rotary member drive surface.

7. The rotary pump as recited in claim 2 wherein the pumping unit includes a pivotable shoe attached to the piston driven end and having a contact surface, the shoe contact surface being disposed generally against the transfer member to couple the piston with the rotary drive member.

8. The rotary pump as recited in claim 1 wherein the coupler assembly includes a biasing subassembly configured to bias the piston driven end generally toward the drive surface of the rotary drive member to operably couple the piston with the rotary drive member.

9. The rotary pump as recited in claim 8 wherein the biasing subassembly includes: an engagement member coupled with the piston; and a biasing member configured to bias the engagement member generally toward the rotary member drive surface so as to maintain the piston driven end coupled with the rotary drive member.

10. The rotary pump as recited in claim 9 wherein: the coupler assembly includes a transfer member disposed generally against the rotary member, the piston driven end being disposed generally against the transfer member, the transfer member generally oscillating about a center point located generally on the drive axis during rotation of the rotary drive member to thereby displace the piston linearly along the axis; and the biasing member is configured to bias the engagement member generally toward the transfer member to maintain the piston driven end disposed against the transfer member.

11. The rotary pump as recited in claim 10 wherein the biasing subassembly further includes a pivot joint connecting the engagement member with the biasing member, the pivot joint being configured to permit the engagement member to pivot about a center point on the drive axis spaced from the transfer member center point such that the engagement member oscillates with the transfer member to maintain the piston driven end disposed against the transfer member.

12. The rotary pump as recited in claim 11 wherein the pivot joint includes a socket member coupled to the engagement member and having a generally spherical cavity and a ball member disposed at least partially within the cavity and attached to the biasing member.

13. The rotary pump as recited in claim 12 wherein the socket member is movably coupled with the engagement member such that linear displacement of the socket displaces the pumping unit along the pump axis, the socket member being angularly displaceable about the drive axis while the engagement member remains generally at a fixed angular position with respect to the axis.

14. The rotary pump as recited in claim 10 wherein the engagement member includes a generally circular plate with at least one opening, a portion of the piston being disposed within the opening so as to couple the plate with the piston.

15. The rotary pump as recited in claim 14 wherein: the pump includes a plurality of pumping units spaced circumferentially about the drive axis, each pumping unit having a piston linearly displaceable along a separate pump axis spaced from and extending generally parallel with respect to the rotation axis, each piston having a working end configured to pressurize a fluid and an opposing driven end; and the engagement plate includes a plurality of the holes spaced circumferentially about the plate, each hole being configured to receive a portion of a separate one of the pistons; and the biasing member is configured to bias the plate generally toward the transfer member to maintain all of the piston driven ends disposed against the transfer member.

16. The rotary pump as recited in claim 1 wherein the rotary drive member includes a generally cylindrical block with a circumferential outer surface and opposing first and second axial ends, the first block end being connected with the drive shaft and the second end having an angled face providing the rotary drive surface.

17. The rotary pump as recited in claim 1 wherein the piston includes: a drive pin having opposing first and second ends, the pin first end providing the piston driven end; and a plunger having opposing first and second ends, the plunger first end providing the piston working end and the plunger second end being attached to the piston second end.

18. The rotary pump as recited in claim 1 wherein: the pumping unit includes a base having a bore, the bore having a drive section with a first diameter and a pressurizing section with a second diameter, the first diameter being substantially larger than the second diameter; the drive pin is at least partially disposed in the drive section and has a diameter extending perpendicularly with respect to the pump axis; and the plunger is at least partially disposed within the pressurizing section and has a diameter extending generally perpendicularly with respect to the pump axis, the drive pin diameter being substantially larger than the plunger diameter.

19. The rotary pump as recited in claim 18 wherein one of: the base includes a block, the bore drive and pressurizing sections extending within the block; and the base includes a first block providing at least a portion of the bore drive section and a second block providing at least a portion of the bore pressurizing section, the second block being connectable with the first block such that the base bore extends through the first and second blocks.

20. A pumping unit for a high pressure rotary pump, the pump having a housing, a drive shaft disposed at least partially within the housing and being rotatable about a drive axis, and a rotary drive member connected with the shaft, the pumping unit comprising: a drive base coupled with the pump housing and having at least one bore providing at least a portion of a drive chamber and a pump axis extending longitudinally through bore; a pressurizing base having bore and being removably connected with the drive base such that the pressurizing base bore is coaxially aligned with the at least one drive base bore and the pump axis extends longitudinally through the pressure bore, the pressurizing base bore at least partially providing a pressure chamber; and a piston disposed at least partially within the drive bore and at least partially within the pressurizing bore so as to be linearly displaceable along the pump axis, the piston including: a drive portion disposed at least partially within the drive chamber, the drive portion having a first, driven end operably engaged with the rotary drive member and a second opposing end; and a pressurizing portion disposed at least partially within the pressure chamber, the pressurizing portion having a first end configured to pressurize fluid within the pressure chamber and an opposing second end connected with the drive portion second end.

21. The pumping unit as recited in claim 20 wherein the piston pressurizing portion is removably connected with the piston drive portion such that the pressurizing base and the piston pressurizing portion are each removable from the pump while the drive portion remains engaged with the rotary drive member.

22. The pumping unit as recited in claim 20 wherein: the drive bore has a first diameter and the pressurizing bore has a second diameter, the first diameter being substantially larger than the second diameter; and each one of the piston drive portion and the piston pressurizing portion has a diameter extending generally perpendicularly with respect to the pump axis, the drive portion diameter being substantially larger than the pressurizing portion diameter.

23. The pumping unit as recited in claim 20 wherein one of: the drive base includes a block having opposing surfaces, the bore extending generally between the two surfaces; and the drive base includes a first block having a through-hole, the through-hole providing at least a portion of the drive chamber, and a second block having a bore providing at least a portion of the pressure chamber, the second block being connectable with the first block such that the second block bore is coaxially aligned with the first block through hole along the pump axis.

24. The pumping unit as recited in claim 20 wherein: the drive base includes a generally cylindrical block connected with the housing and having a through hole providing at least a portion of the drive bore; and the pressurizing base includes a cylinder having a bore providing at least a portion of the pressurizing bore, the cylinder being removably connectable with the block such that the cylinder bore is aligned with the block through hole.

25. The pumping unit as recited in claim 20 wherein the drive base is one of connected with the pump housing and integrally formed with the pump housing.

26. The pumping unit as recited in claim 20 the drive portion includes a generally circular cylindrical rod having an outside diameter; and the pressurizing portion includes a generally circular cylindrical rod connected with the drive rod and having an outside diameter, the drive rod diameter being substantially larger than the pressurizing rod diameter.

27. The pumping unit as recited in claim 20 wherein a ratio of the drive portion diameter to the pressurizing portion diameter is at least about two to one.

28. The pumping unit as recited in claim 20 wherein: the rotary drive member has a drive surface extending at skewed angle with respect to the drive axis and facing generally toward the pumping unit base; and the piston drive portion driven end is operably coupled with the rotary drive surface such that rotation of the rotary drive member reciprocates the piston along the pump axis.

29. The pumping unit as recited in claim 20 further comprising a seal member fixedly disposed within the base bore and having a central opening, the pressurizing member extending through the seal opening, the seal being configured to prevent fluid flow between the compression chamber and the drive chamber.

30. The pumping unit as recited in claim 29 wherein water is disposeable within the compression chamber and a lubricant is disposeable within the drive chamber, the seal being configured to prevent water from entering the drive chamber and lubricant from entering the compression chamber.

31. The pumping unit as recited in claim 20 wherein: the pressurizing base includes an interior surface extending circumferentially about the pump axis and defining the pressure chamber and the piston pressurizing portion has an outer circumferential surface extending about the axis, the pressurizing portion outer surface being spaced radially inwardly from the chamber inner surface such that an annular clearance passage is defined between the inner and outer surfaces; and the pumping unit further comprises a seal disposed within one of the drive chamber and the pressure chamber and having a central opening, the pressure portion extending through the opening, the seal being configured to prevent any fluid passing through the clearance passage from entering the drive chamber.

32. A high pressure rotary pump comprising: a housing; a drive shaft disposed at least partially within the housing and being rotatable about a drive axis; a rotary drive member connected with the shaft and having an angled drive surface; a drive base coupled with the pump housing and having a plurality of the drive bores spaced circumferentially about the pump drive axis, each drive base bore providing a portion of a separate drive chamber, and a plurality of pump axes each extending longitudinally through a separate one of the bores; a plurality of pressurizing bases each having a bore, each pressurizing base being removably connectable with the drive base such that each pressurizing base bore is coaxially aligned with a separate one of the drive base bores such that one pump axis extends longitudinally through the pressurizing bore, each pressurizing base bore at least partially providing a pressure chamber; and a plurality of pistons each disposed at least partially within a separate one of the drive bores and at least partially within the pressurizing bore aligned with the one drive bore so as to be linearly displaceable along the associated pump axis, each piston including: a drive portion disposed at least partially within the associated drive chamber, the drive portion having a first, driven end operably engaged with the rotary drive member and a second opposing end; and a pressurizing portion disposed at least partially within the associated pressure chamber, the pressurizing portion having a first end configured to pressurize fluid within the pressure chamber and an opposing second end connected with the drive portion second end.

33. The rotary pump as recited in claim 32 wherein each piston pressurizing portion is removably connected with the associated piston drive portion such that each pressurizing base and each piston pressurizing portion is removable from the pump while the associated drive portion remains engaged with the rotary drive member.

34. The rotary pump as recited in claim 32 wherein each pressurizing base is removable from the drive base while each other pressuring base remains connected with the drive base.