US 3433163 A
Description (OCR text may contain errors)
March 18, 1969 H. E. SHEETS ET AL 3,433,163
Filed Nov. '7. 1966 ENQ United States Patent O U.S. Cl. 103-87 Int. Cl. F0441 .73/02, 29/06 4 Claims ABSTRACT F THE DISCLOSURE A multi-stage, axial flow liquid pump with a selfcontained, floodable drive motor. In inside-out motor arrangement, the motor stator is mounted concentrically within the contines of the rotor. Cooling and lubrication are provided by the liquid being pumped.
This invention relates in general to fluid pumps. It deals particularly with a motor-pump arrangement especially suited for pumping a liquid such as a chemical or water or the like.
It is an object of the present invention to provide a new and improved axial flow, motor-pump arrangement.
It is another object to provide a new and improved variable speed, multi-stage, floodable, axial ilow motorpump arrangement.
It is still another object to provide a multi-stage axial flow motor-pump arrangement of the aforedescribed character which is more compact and lighter in weight than presently known centrifugal motor-pumps presently m use.
It is yet another object to provide an axial flow, motorpump arrangement of the aforedescribed character which eliminates the necessity of providing shaft sealing between the motor and pump.
It is a further object to provide a new and improved motor-pump arrangement which generates minimal vibration and ilow noise.
It is a further object to provide a new and improved variable speed, multi-stage, floodable, axial How motorpump arrangement which achieves comparatively high pressures with low operating speeds.
It is another object to provide a slotted blade multistage motor-Huid pump which achieves comparatively greater pumping efficiency.
It is yet a further lobject to provide a motor-pump arrangement of the aforedescribed character which employs the liquid being pumped as a bearing lubricant.
It is another object to provide a motor-pump arrangement wherein the center of gravity of the motor and the pump are at approximately the same point.
The foregoing and other objects are realized in accord with the present invention by providing a multi-stage, axial ow liquid pump with a self-contained variable speed, oodable, drive motor. No shaft connection between the motor and pump is required, eliminating all shaft sealing problems. This is highly advantageous in many applications, such as a chemical pumping system, for example. The motor and pump are substantially coextensive with virtually common centers of gravity.
The motor-pump arrangement is radially compact, having a small diameter. The small diameter of `the pump rotors minimizes unbalanced mechanical forces. The axial flow design produces no unbalanced loads at offdesign conditions. Both aid in keeping the vibra-tion and fluid noise level very low. In addition, particularly when utilized 4with slotted rotor and/or stator blades, the lower operating speeds made possible produce higher pressure ratios while further minimizing self-noise.
3,433,163 Patented Mar. 18, 1969 ice The interface between stages can be yanalyzed to determine the cause of increased efficiency. It is well known that wake effects between sequential blade rows affect performance. Width of the wake is a function of drag co-ecient. It has been discovered that the slotted blade arrangement will reduce drag co-ellicient in highly loaded profile sections and increase pumping eihciency. The consequent reduction in width of the wake for slotted blades will therefore reduce the non-homogeneous flow pattern entering the next blade row. An additional factor indicates that at a low Reynolds number (1.l l05) the loss co-eicients are highly dependent upon profile thickness. The slotted blade arrangement provides for an inherently thinner prole conguration and the presence of two blades of short chord and therefore thin sections further reduce loss co-efiicients 'and therefore provides substantially less non-homogeneous ow into the next blade row. Laminar flow separation is also reduced by the slotted blade grouping and its detrimental effects on later blade rows is reduced. In addition, the cumulative boundary layer thickness is removed 1by the slot and the resultant wake is reduced to two substantially smaller wake areas of turbulence. All the above factors result in an increase in pumping efficiency.
In a preferred form of the motor-pump arrangement embodying features of the present invention, an inside-out motor configuration is employed. This arrangement includes a motor stator mounted within the contines of a rotor. The motor rotor carries rotor blades on its periphery while the inside of the housing mounts corresponding stator blades. Lubrication is provided by the liquid being pumped. This construction is approximately 70 percent lighter and 80 percent smaller in volume than centrifugal pumps of a comparable capacity.
A motor-pump arrangement embodying features of the present invention is also constructed with the motor stator encircling the rotor, and an inside-out pump configuration. This multi-stage, axial ow version of the invention is approximately 40 percent lighter and 4S percent `smaller in volume than comparable centrifugal motor pumps, however.
The invention, both as to its organization and method of operation, taken with further objects and advantages thereof, ywill best be understood by reference to the following drawings in which:
FIGURE 1 is a longitudinal sectional view, in diagrammatic form, through a motor-pump arrangement embodying features of -a first and preferred form of the invention; FIGURE 2 is a View taken along line 2-2 of FIGURE 1;
FIGURE 3 is a longitudinal sectional view, in diagrammatic form, through a motor-pump arrangement embodying features of a second form of the invention;
FIGURE 4 is a View taken along line 4 4 of FIG- URE 3; and
FIGURE 5 is an enlarged inset view of a portion of the lubrication system in the pump illustrated in FIGURES 1 and 2.
Referring now to the drawings, and particularly to FIGURES l and 2, .a preferred form of the motor-pump arrangement embodying features of the present invention is seen diagrammatically at 10. The motor-pump arrangement 10 illustrated is ideally suited for use in pumping chemicals or the like as well as in other applications. For ease of explanation, it will be described here generally in terms of a liquid pump.
The motor-pump arrangement 10 is designed to pump liquid from the inlet pipe 11 of a system to the outlet pipe 12 thereof, through a pump housing 15.'The housing 15 of the motor-pump 10 is joined to the inlet pipe 11 and the outlet pipe 12 at conventional liquid tight joints 16.
The housing comprises a central circular cylindrical section and somewhat conical end sections 21. The central section 20 is joined to the end sections 21 at liquid tight joints 22. The end sections 21 are, in turn, joined to the inlet pipe 11 and the outlet pipe 12 at the liquid tight joints 16 referred to above.
Inside the housing 15 of the motor-pump arrangement 10y is a completely floodable electric drive motor Z5. The drive motor 25 is co-axial with the housing 15 and extends from inside one conical end section 21 thereof to the opposite end of the housing inside the other conical end section 21. The motor 25 is supported from the end sections 21 and is effective to drive the pump 26 of the motor-pump arrangement 10 at a selected, variable speed, to pump liquid in the aforementioned system.
The -oodable motor 25, which might be characterized as an inside-out motor, comprises a central core having spools 32, 33 on its opposite ends. The spools 32, 33 are identical in construction, each being generally conical or bullet shaped. The end sections 21 of the housing 15 are similarly shaped to conform to the shape of the spools 32, 33, leaving a flow path for the liquid between the outer surface 35 of each spool 32, 33, and a corresponding inner surface 36 in each end section 21.
The core 30 and spools 32, 33 are mounted within the housing 15 on radially disposed struts 37 extending between the outer spool surfaces 35 and the inner housing surface 36 of corresponding end sections 21. The struts `37 are airfoil shaped in cross-section to provide minimal impedance of liquid flow through the motorpump arrangement 16.
The core 30 includes a stator armature winding 45 which extends between the opposite end spools 32, 33. The winding 45 is generally conventional in construction, with armature slot number and size, as well as winding configuration, chosen in keeping with various factors, including the characteristics of the supply voltage. The core 30 is suitably encapsulated or canned in liquid impervious plastic or the like to protect it from the liquid being pumped. Mounted co-axially with the core 30, for rotation outside of it, is a cylindrical rotor 49. The rotor 49 is supported for rotation on identical bearing assemblies 50 mounted on corresponding spools 32, 33. In the motorpump arrangement 10 the rotor 49 is a non-corrosive, alloy steel cylinder. However, this solid cylinder construction is merely exemplary and the rotor might also be constructed as a cage assembly or the like.
The cylinder rotor 49 has identical bearing seats 55 machined from its inside surface 56 immediately adjacent its opposite end faces 57. The bearing seats 55'- are adapted to ride in bearing relationship on corresponding journal .bearings 60 of the ybearing assemblies 50. The journal bearings `60 are preferably fabricated of a polymer plastic which utilizes the liquid being pumped as a lubricant, in a manner hereinafter described in detail.
The journal bearings 60 are generally cylindrical in configuration, as will be noted, and each has a radially extending iange 61 formed at its outer end. The flange 61 and corresponding -outer end of each bearing 60 seat snugly against the backing of a corresponding spool 32, 33.
In addition to the journal Ibearings 60, annular thrust bearings 65 are provided. Each thrust bearing 65 is seated snugly around a corresponding journal bearing 60 and is seated against its flange 61. The thrust bearings 65 limit longitudinal motion of the cylinder rotor 49 and support the thrust exerted by liquid pressure acting upon the rotor during operation of the motor-pump arrangement 10. The thrust Ibearings 65 are similar in construction to the journal bearings 60 in that they are fabricated of a polymer plastic which is lubricated by the liquid being pumped in a manner hereinafter described.
Mounted on the outer surface of the rotor cylinder 39 in a conventional manner are la plurality of rotor blades 70. The rotor cylinder 49 and the blades 70 thus define .4 the rotor of the pump 26. The rotor blades 70l are arranged in a series of evenly spaced stages 71. In the present illustration there are nine of these stages, each of which contains eleven rotor blades.
The rotor blades 70 are identical in construction. They are airfoil shaped and, in addition, are radially slotted from hub to tip in the manner disclosed in Sheets U.S. Patent No. 3,075,743, assigned to the same assignee as the present invention.
Arranged in stages which alternate with the stages 71 of rotor blades 70, and secured to the inner surface of the central housing section 2t)y in a similarly conventional manner, are a plurality of stator blades 81. The stator blades 81 are preferably identical in construction to the rotor blades 70. However, in the motor-pump arrangement 10l described herein, there are nineteen stator 'blades 81 in each stage 80.
The blade 70, 81 arrangement hereinbefore described is an identical stage arrangement. More specifically, there are eleven rotor blades 70 in each stage 71 of rotor blades and nineteen stator blades 81 in each stage 80 of stator blades. However, the blade 70, 81 arrangement .might also be of the mixed stage type. In such case, the even stages might contain ten vblades in the rotor and seventeen blades in the stator, while odd stages have eleven blades in the rotor and nineteen blades in the stator (the same as the identical stage arrangement).
It is primarily because of the inside-out arrangement of the motor-pump arrangement 10 that its diameter is extremely small, namely, about 50 percent larger than the pipe diameter. The motor-pump housing 15, for example, has an outside diameter of only six inches against a pipe diameter of about four inches. The rotor blades 70 are also extremely small, of course. Their hub diameter is of the nature of 4.25 inches while their tip diameter is only 5.64 inches. The motor-pump arrangement 10 is, in fact, 8O percent smaller than comparable capacity centrifugal motor-pumps and 70 percent lighter, all while providing increased eiciency over such centrifugal pumps.
The small diameter of the motor-pump arrangement 10 achieved' with the aforedescribed construction embodying features lof the present invention engenders a rvery low level of vibration noise. As pointed out, unbalanced mechanical forces are minimized and no unbalanced loads are aifected at off-design conditions.
Furthermore, -by the use of the slotted blades disclosed in the aforementioned Sheets U.S. patent, higher turning angles are permitted in the blade 70, 81 arrangement, thus developing a higher pressure rise in each stage with lower rotational speeds and lower ow velocities. This further minimizes iow noise. The motor-pump arrangement 10 effects a noise level of from ten to thirty decibels less than a corresponding centrifugal motor-pump arrangement, for example.
In operation of the motor-pump arrangement 10, the rotation of the cylindrical rotor 49 and the rotor blades 70 `mounted thereon draws liquid into the motor-pump housing 15 and forces it through to the outlet pipe `12. The construction and capacity of the motor-pump arrangement 10 hereinbefore described is such that a pumping rate of 600 gallons per minute -is achieved with a pressure `rise or head of sixty-seven feet.
Rotation of the rotor cylinder 49 is accomplished in a conventional manner by torque induction in the cylinder from the motor stator armature winding 45. The motor 25 is designed and constructed so that a design speed of 1100 r.p.m. is achieved. Current for operation of the motor 25 is supplied from a suitable outside source. Otherwise, the motor-pump arrangement 10 is completely self-contained.
Since there is no shaft connection between a driving motor 25 and a pump 26, there is no shaft sealing problem. This makes the motor-pump arrangement 10 ideal for use in pumping highly corrosive chemicals and the like, and for many other applications.
The motor stator winding 45 is cooled by a cooling system 90 according to the present invention. The cooling system 90 includes a cooling conduit 91 formed through the core 30 and spools 32, 33 on their common axis. The conduit 91 extends from an axial inlet opening 92 in the spool 33 adjacent the outlet pipe 12 to an axial outlet opening 93 in the spool 32 adjacent the inlet pipe 11.
A generally cone shaped flow diverter cap 94 is mounted with airfoil shaped struts 94a on the spool 32 over the outlet opening 93 of the conduit 91. Liquid drawn from the pipe 11 through the motor-pump arrangement in the manner hereinafter described is diverted from the conduit opening 93 by the diverter cap 94.
As the liquid under pressure is driven from the motorpump arrangement 10, a portion of it is caught by the diverter cap 95 similar to the diverter cap 94 and mounted in an identical manner with struts 95a over the inlet opening 92 of ythe conduit 91. The curved shape of the inner surface 98 in the conical diverter cap 95 diverts liquid from the pumps outlet ow into the conduit 91 and forces it through the conduit towards the inlet pipe 11 in cooling relationship with the stator core 30. The cooling water passes out of the conduit 91 through the outlet opening 93 of the conduit and re-enters the ow of water being pumped. Suction created around the diverter cap 94 by the passage of water being drawn into the housing and past the cap 94 enhances the flow of cooling liquid from the conduit 91 :after it has passed through the core 30.
As the cooling liquid courses through` the conduit 91 from inlet 92 to outlet 93, it passes through a restrictive orifice plate 101 placed in Ithe conduit near the inlet 92. Immediately upstream of this restrictive orifice 101, on its high pressure side, a lubrication line 102 (shown diagrammatically) is tapped out of the conduit. The line 102 extends in two branches, 102:1 and 102]), through the core 30 and spools 32, 33 to communication with lubrication ports 105 in the bearings 60. Lubrication lines 102:1 and 10211 are sized such that part of the lubrication uid is diverted to one line, 1020:, to lubricate the aft bearing assembly (journal and thrust bearing), and part into the other line 102b, to lubricate the forward bearing assembly.
Liquid under pressure is forced through the line 102 to lubricate the bearings 60 and 65 through the ports 105. Slots would be incorporated in the journal bearing and thrust bearing to permit the lubricating fluid to lubricate the bearing and then go into the main fluid stream. Spool pieces 32 and 33 are positioned so that there is a clear path through the lubricating Huid line. This lubricating liquid is then withdrawn from the bearings 60 and 65 through lubrication ports 106 and returned through lines 107 to the low pressure side of the conduit 91, downstream of the orifice 101. Preferably, the entering lubrication ports 105 are 180 displaced from the exit ports 106 circumferentially of the bearings 60 and 65.
Turning now to FIGURES 3 and 4 of the drawings, an alternative form of the motor-pump arrangement embodying features of the present invention is seen diagrammatically at 110. The motor-pump arrangement 110 differs from the motor-pump arrangement 10 hereinbefore described principally in that it employs a conventional stator armature outside, rotor inside motor 125 construction. The pump 126 arrangement is, according to the invention, however, an inside-out construction, as will hereinafter be made clear. The motor-pump arrangement 110 is 40 percent lighter and 48 percent smaller than comparable centrifugal pumps, as has been pointed out.
In the similar general context of a liquid pumping system, the motor-pump arrangement 110 pumps liquid from the inlet pipe 111 of the system to the outlet pipe 112 thereof, through the pump housing 115. The housing 115 of the motor-pump arrangement 110 is joined to the inlet pipe 111 and the outlet pipe 112 at conventional liquid tight joints 116.
The housing comprises a central circular cylindrical section and somewhat conical end section 121. The central section 120 is joined to the end of the sections 121 at liquid tight joints 122. The end sections 121 are, in turn, joined to the inlet pipe 111 and the outlet pipe 112 at the liquid tight joints 116.
Like the motor-pump arrangement 10, the completely floodable electric motor 125 drives the pump 126-, both mounted within the housing 115. The motor 125 comprises a circular cylindrical armature 130. The armature 1-30 is concentrically mounted in its protective covering 131 within the housing section, where it is suitably xed.
Rotatably mounted within the contines of the armature is a circular cylindrical tube 13'5 fabricated of noncorrosive alloy steel. The composition and conguration of the tube 135 are such that the armature 130 readily induces a magnetic eld in it to cause its rotation. At its opposite ends 136 and 137, the tube is mounted for rotation about its axis on conventional sealed roller bearings 140 and annular bearing support rings 141. The rings 141 are concentrically mounted Within opposite ends of the housing section 120. The sealed roller bearings 140 provide both axial and thrust bearing support for the rotating tube 135.
Snugly seated within the tube 135 for rotation therewith is the rotor cylinder for the pump 126. The cylinder 150 is also fabricated of a non-corrosive alloy steel.
Mounted on the inner surface of the rotor cylinder 150 are a plurality of rotor blades 151. The blades 151 are arranged in a series of evenly spaced stages 152. Like the motor-pump arrangement 10, the motor-pump arrangement 1-10 is an identical stage arrangement construction and there are nine of these stages 152, each of which contains eleven rotor blades.
Mounted co-axially of the rotor cylinder 150 within its confines (and the tips of the blades 151) and extending from one end section 121 of the housing 115 to the other end section 121 is a stator body 155. The stator body 155 has an elongated tubular shape and is generally conical or bullet shaped at its opposite ends 156. The stator body 155 is mounted on the motor-pump housing 115 on radially disposed struts 157 extending between its outer end surfaces 158 and the innerhousing surface 159 of corresponding end sections 121. Once again, the struts -157 are airfoil shaped in cross-section to provide minimal impedance of water ow through the motor-pump arrangement 10.
Mounted on the outer surface 160 of the body 155 are a plurality of stator blades 161 arranged in stages 162 which alternate with the stages 152 of rotor blades 151. The stator blades 161 are preferably identical in construction to the rotor blades 151. There are nineteen stator blades 161 in each stage 162.
In operation of the motor-pump arrangement 1-10; rot-ation of the rotor cylinder 150 and the rotor blades 151 mounted thereon draws water into the motor-pump housing 115 from the inlet pipe 111 and pumps it through the housing r115 to the outlet pipe 112.
There is no shaft connection between the driving motor 125 and pump 126, and accordingly, there is no shaft sealing problem. The liquid being pumped cools the armature 130. The motor-pump arrangement 110 is a completely self-contained unit, requiring only electrical power from an outside source for its operation. The pump 126 itself is an inside-out arrangement, the stator blades 161 being fixed within the rotor blades 151.
While the embodiment described herein is at present considered to be preferred, it is understood that various modifications and improvements may be made therein, and it is intended to cover in the appended claims all such modifications and improvements as fall within the true spirit and scope of the invention.
What is ydesired to be claimed and secured by Letters Patent of the United States is las follows:
1. A quiet, multi-stage, axial ow motor-pump arrangement for pumping a liquid, comprising: an elongated cylindrical pump housing having an inlet and an outlet, a motor stator mounted in said housing, said motor stator including an elongated armature mounted substantially on the axis of said housing, an elongated cylindrical motor rotor co-axial with said motor stator and rotatable around said armature on said axis to form a motor assembly, a plurality of pump rotor blades annularly mounted on the outer periphery of said motor rotor in an axially spaced series of stages, and a plurality of pump stator blades annularly mounted in said housing in an axially spaced alternating series of stages to form a pump yassembly for pumping liquid from said inlet to said outlet, bearing means supporting said motor rotor in said housing for rotation relative to said motor stator, a system for cooling said armature with the liquid being pumped, said system comprising cooling conduit means extending through said armature, cooling liquid from the liquid being pumped being diverted and driven through said conduit means to cool said armature, and lubrication means for carrying liquid lbeing pumped by said motor-pump arrangement to said bearing means to lubricate said bearing means.
2. The motor-pump arrangement of claim 1 further characterized by and including flow diverter means adjacent said outlet for diverting a portion of the liquid being pumped through said conduit means to cool said armature and discharge adjacent said inlet.
3. The motor-pump arrangement of claim 2 further characterized in that said lubrication means include lubrication port and line means connecting said cooling conduit to said bearing means.
4. The motor-pump arrangement of claim 3 further characterized by and including stricture means in said conduit for creating a substantially higher pressure upstream of said stricture means in said conduit means then downstream thereof, said lubricating liquid being drawn from said conduit means upstream of said stricture means. l
References Cited UNITED STATES PATENTS 1,632,357 6/1927 White.
2,256,659 9/ 1941 Thrasher.
2,171,460 8/ 1939 Thrasher.
3,075,743 l/ 1963 Sheets.
3,132,595 5/1964 Bower.
3,143,972 8/1964 Smith.
3,194,487 7/1965 Tyler et al. 230-122 2,851,956 9/1958 Lung.
3,288,075 11/1966 Lung 103-102 HENRY F. RADUAZO, Primary Examiner.
U.S. Cl. X.R.