Abstract:
A pump includes a pump housing having an impeller recess therein and a pump outlet and an impeller disposed in the impeller recess. First and second separate volute passages are disposed in the pump housing and are further disposed in fluid communication between the impeller recess and the pump outlet. Motive power and fluid are supplied to the impeller recess, thereby inducing fluid flow therein. The fluid flow is divided into the separate volute passages and the divided flow is recombined in a convergence passage before exiting the pump outlet.

Description:
This application claims the benefit of prior provisional patent application Serial No. 60/349,997 filed Nov. 9, 2001. 
    
    
     TECHNICAL FIELD 
     The present invention relates generally to pumps, and more particularly to a pump driven by an engine. 
     BACKGROUND 
     Internal combustion engines utilize one or more fluid pumps that circulate cooling fluid in cooling passages. Often, these pumps are gear-driven for reliability. In recent years, the ratings of engines have been increased, leading to the need for increased pump capacity so that adequate cooling can be accomplished. This increased capacity can be achieved by increasing the driving speed of the pump and/or increasing pump size. 
     The location and diameter of the pump driving gear, together with the diameter of the driven pump gear, determine the possible mounting location(s) of the pump along the arc of the driving gear. Efforts to increase pump capacity by increasing the gear-driven speed of the pump have proved problematic, in that the space available for the pump is extremely limited. Specifically, pump speed can be increased through a reduction in the diameter of the driven pump gear. However, such a solution requires the pump to be moved toward the engine block to maintain the gear mesh. In some installations, the engine block or other engine components may interfere with the pump body to an extent that such a design solution is not possible. 
     Centrifugal pumps with radial volutes have been manufactured for many years. An axial volute scroll pump is utilized on a tractor engine manufactured and sold by John Deere under part number RE53538. 
     In addition, turbochargers have been designed having a divided housing for a turbine. See, for example, U.S. Pat. Nos. 2,444,644 and 3,941,104 and other patents cited during the prosecution of the latter patent. These types of housings have multiple inlets that receive exhaust gases from separate engine cylinders, multiple volute passages that converge into a single main turbine recess and a single outlet. The multiple inlets and volute passages permit the extraction of energy from the exhaust gas flow paths from the cylinders. 
     The present invention is directed to overcoming one or more of the problems or disadvantages associated with the prior art. 
     SUMMARY OF THE INVENTION 
     In accordance with one aspect of the present invention, a pump includes a pump housing having an impeller recess therein and a pump outlet. An impeller is disposed in the impeller recess and first and second separate volute passages are disposed in the pump housing in fluid communication between the impeller recess and the pump outlet. 
     In accordance with a further aspect of the present invention, an engine system includes an engine and a pump operatively coupled to the engine, wherein the pump includes a housing having an impeller recess therein and a pump outlet. An impeller is disposed in the impeller recess and first and second separate volute passages are disposed in the pump housing in fluid communication between the impeller recess and the pump outlet. 
     In accordance with yet another aspect of the present invention, a method of pumping fluid comprises the steps of providing a pump having a housing wherein the pump housing includes an impeller recess having an impeller therein and a pump outlet and supplying fluid to the impeller recess and motive power to the impeller thereby to induce fluid flow in the impeller recess. The fluid flow is divided into first and second separate flows in the pump housing and the fluid flows are recombined in a convergence passage in the pump housing adjacent the pump outlet. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a fragmentary and partially exploded front trimetric view of an engine having an engine cover removed to reveal a pump according to one aspect of the present invention; 
     FIG. 2 is a trimetric view similar to FIG. 1 with pump gearing removed; 
     FIG. 3 is a fragmentary and partially exploded rear trimetric view of the engine of FIG. 1; 
     FIG. 4 is a plan view of the pump of FIG. 1; 
     FIG. 5 is a front elevational view of the pump of FIG. 1; 
     FIG. 6 is a rear elevational view of the pump of FIG. 1 with an intake cover removed to reveal an impeller disposed in an impeller recess; 
     FIG. 7 is a rear elevational view similar to FIG. 6 with the pump impeller removed to reveal the impeller recess; 
     FIG. 8 is a side elevational view of the pump of FIG. 1 taken generally along the view lines  8 — 8  of FIG. 7; 
     FIGS. 9-13 are sectional views taken generally along the lines  9 — 9 ,  10 — 10 ,  11 — 11 ,  12 — 12  and  13 — 13 , respectively, of FIG. 8; 
     FIGS. 14-17 are sectional views taken generally along the lines  14 — 14 ,  15 — 15 ,  16 — 16  and  17 — 17 , respectively, of FIG. 7; 
     FIGS. 18 and 19 are trimetric front and rear views of assembled foundry cores for creating the recess and passages of the pump of FIGS. 1-17; 
     FIG. 20 is a trimetric view of one of the cores of FIGS. 18 and 19; and 
     FIGS. 21 and 22 are trimetric views of opposite sides of another of the cores of FIGS.  18  and  19 . 
    
    
     DETAILED DESCRIPTION 
     Referring to FIGS. 1-4 a portion of an internal combustion engine  30  is shown. The engine  30  includes an engine block  32 , an end plate  34  secured to the engine block  32  and a pump  36  according to the present invention secured to the end plate  34  by bolts  38  (one of which is shown in the FIGS.). The pump  36  includes a pump gear  40  which is engaged by and driven by a journaled engine driving gear  42 . The driving gear  42  is, in turn, driven by a crankshaft gear  44 . While the pump  36  is adapted to supply coolant under pressure to the engine  30 , it should be noted that the pump  36  may instead be adapted to pump any other fluid and/or may be associated with and/or driven by a prime mover other than the engine  30 , as desired. 
     Referring specifically to FIGS. 3,  4  and  8 , the pump  36  includes a main pump inlet  50 , a bypass pump inlet  51  and a pump outlet  52 . While not shown in the FIGS., the main pump inlet  50  is coupled to a radiator outlet and the bypass pump inlet is coupled to a bypass outlet of a bypass valve. The pump outlet  52  is coupled to an oil cooler  54  (FIGS.  1 - 4 ). A plurality of fluid ports  56  is provided on a rear intake cover  58  (FIGS. 1-4) of the pump  36  to allow heater hoses to be connected thereto. In the illustrated embodiment heater hoses are not connected to the pump, and hence, the fluid ports  56  are closed off by threaded plugs  59  (one of which is illustrated in FIG.  3 ). 
     Referring next to FIG. 5, the pump  36  is illustrated disassembled from the engine  30 . A bearing retainer  60  is bolted or otherwise secured to a pump housing  62 . The bearing retainer  60  retains bearings for a pump shaft  64  which is joined to the pump gear  40 . 
     Referring to FIG. 6, a pump impeller  66  is disposed in an impeller cavity or recess  68  and is mounted on the pump shaft  64  for rotation therewith. Referring also to FIG. 7, the impeller cavity  68  is partially defined by a base surface  70  having a depressed portion  72  that overlies a passage described in greater detail hereinafter. 
     Referring next to FIGS. 7-17, the impeller cavity  68  is disposed in fluid communication with first and second volute passages  80 ,  82 . Preferably, the first volute passage  80  is separate from the second volute passage  82 . In addition, the first volute passage  80  includes a first portion  80   a  and a second portion  80   b  wherein the first portion  80   a  ends and the second portion  80   b  begins at a knife edge  81 . Still further, as seen in FIGS.  8  and  14 - 17 , the second portion  80   b  is preferably disposed substantially axially adjacent the second volute passage  82 . Also preferably, each of the first passage portion  80   a  and the second volute passage  82  has a cross-sectional size that increases with circumferential distance toward a convergence passage  84  located in the pump housing  62  just upstream of the pump outlet  52 . Preferably, the cross-sectional sizes of the passage portion  80   a  and the passage  82  continuously and linearly increase with circumferential distance toward the convergence passage  84  and the pump outlet  52 . Still further in accordance with the preferred embodiment, the first volute passage  80  divides from the impeller cavity  68  at the knife edge  81 , wherein the latter is disposed substantially diametrically opposite the outlet  52 . Also, the cross-sectional size of the passage portion  80   b , preferably remains substantially constant throughout the length thereof. The first volute passage  80  (specifically, the passage portion  80   b ) reconverges with the second volute passage  82  at the convergence passage  84 . 
     FIGS. 18-22 illustrate cores  100  and  102  that may be used to create the voids and passages in the pump housing  62 . In particular, the core  100  includes a portion  110  that forms the second volute passage  82 . As seen in FIG. 20, the core  100  further includes a portion  112  having a substantially flat face  114  and a portion  116  having a substantially flat face  118 . Still further, the core  100  includes a raised portion  120  that creates a passage  122  (FIG. 11) underlying the depressed portion  72 . The passage  122  is described in greater detail in U.S. Pat. No. 5,713,719, owned by the assignee of the present application and the disclosure of which is incorporated by reference herein. Specifically, the passage  122  permits cooling fluid to pass from the first volute passage  80  to the area of the seal for the pump shaft  64 . The fluid flow then passes outwardly from the pump shaft seal through holes  124   a  and  124   b  (FIG. 6) back to the pump inlet  50 . 
     If desired, a further passage  125  created by a core portion  126  (FIGS. 18 and 19) may be provided extending between the pump shaft seal and a weep hole outlet  127  (FIG.  13 ). If desired, the weep hole outlet may be plugged by a porous insert  128  to prevent insects and/or debris from entering and/or obstructing the weep hole outlet  127 . Also, the further passage  125  may be modified to create a sump well therein in accordance with the teachings of U.S. Pat. No. 5,490,762, also owned by the assignee of the present application and the disclosure of which is incorporated by reference herein. 
     The core  102  includes a portion  130  having a substantially flat face  132  and further includes a main portion  134  and an end portion  136  having a substantially flat face  138  (FIGS.  21  and  22 ). 
     Before the casting operation, the cores  100  and  102  are secured together using any suitable method such that the faces  114  and  118  are joined to the faces  132  and  138 , respectively, and so that a surface  140  abuts a surface  142 . Thereafter, during the casting process, the portions  132  and  112  create the passage portion  80   a . In addition, the portion  110  creates the second volute passage  80 , the portion  134  creates the portion  80   b  of the first volute passage  80  and the portions  116  and  136  create the convergence passage  84 . 
     Industrial Applicability 
     The pump  36  is operable when driven by the pump gear  40 , in turn causing the impeller  66  to rotate and induce rotational movement (i.e., flow) of fluid in the impeller cavity  68 . The fluid flow passes through the passage portion  80   a , and thereafter splits and proceeds through the portion  80   b  of the first volute passage  80  and the second volute passage  82 . The separate flows then rejoin one another at the convergence passage  84  and exit the pump  36  at the pump outlet  52 . 
     By dividing the pump flow into axially-displaced passages  80 ,  82 , the pump  36  can have an increased capacity, while at the same time still fit into the limited space available therefor. It should be noted that while the pump described herein may have a lower efficiency rating than conventional pumps, such a potential disadvantage is considered to be outweighed by the ability to provide a higher-capacity pump in a relatively small space. 
     Numerous modifications and alternative embodiments of the invention will be apparent to those skilled in the art in view of the foregoing description. Accordingly, this description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the best mode of carrying out the invention. The details of the structure may be varied substantially without departing from the spirit of the invention, and the exclusive use of all modifications which come within the scope of the appended claims is reserved. 
     Other aspects and features of the present invention can be obtained from a study of the drawings, the disclosure, and the appended claims.