Background Art Numerous pumps have been developed in the past for pumping fluids. For instance, U. S. Patent Nos. 3,244,109 and 4,802,817 disclose centrifugal pumps having housings, which define volute chambers, diffusers, which are mounted in the volute chambers, and impellers which are surrounded by the diffusers in the volute chambers. In these pumps, the housings directly form the volute chambers, while the diffusers are either integrally formed with the housings or are positioned therein in such a manner that their removal is rendered extremely difficult. As a result, the volute chambers and/or the diffusers are not adapted for selective and independent replacement with, for instance, those having different pumping specifications so as to accommodate the changing operational requirements associated with the pumps. Moreover, because various components of the pumps are connected to their associated parts by threads, bolts or the like, assembly and disassembly of the pumps are rendered time-consuming and thus inefficient.

In the foregoing circumstances, there is a need for a pump that is designed

for quick and easy assembly and disassembly and for selective and independent replacement of its components to suit changing operational requirements.

Disclosure of the Invention The present invention overcomes the disadvantages and shortcomings of the prior art discussed above by providing a new and improved apparatus for pumping fluids. More particularly, the apparatus includes a housing having a pump chamber therein. The pump chamber has an opening formed in one end of the housing. An impeller is rotatably mounted in the pump chamber, while a diffuser is mounted in the pump chamber through the opening of the housing and has a portion which radially surrounds the impeller. The apparatus also includes a forming structure, mounted in the pump chamber through the opening, for forming a volute chamber in the pump chamber. The impeller and the diffuser are removably mounted in the volute chamber. The diffuser and the forming structure are discrete from one another and removably mounted in the pump chamber such that the diffuser and the forming structure are independently and selectively replaceable.

The apparatus also includes a connecting pipe for connecting a fluid inlet or outlet of the housing to an external pipe. More particularly, the

connecting pipe includes a body having an inlet end, which is sized and shaped so as to be connected to an external pipe, and an outlet end which is located opposite the inlet end and which is sized and shaped so as to be removably connected to the inlet or outlet of the housing. The inlet and outlet ends includes inlet and outlet openings, respectively, which lie in planes substantially parallel to each other. The inlet opening is radially offset from the outlet opening such that the inlet opening can be positioned at one of an infinite number of different positions, whereby the inlet opening can be connected to an external pipe located at a position different from the position of the inlet or outlet of the housing.

Brief Description of the Drawings For a more complete understanding of the present invention, reference is made to the following detailed description of an exemplary embodiment considered in conjunction with the accompanying drawings, in which: FIG. 1 is an exploded perspective view of a pump constructed in accordance with the present invention; FIG. 2 is a partial cross-sectional view of the pump shown in FIG. 1;

FIG. 3 is a perspective view of a diffuser of the pump shown in FIGS. 1 and 2; FIG. 4 is a cross-sectional view, taken along section line 4-4 and looking in the direction of the arrows, of the diffuser shown in FIG. 3; FIG. 5 is a perspective view of a seal plate unit of the pump shown in FIGS. 1 and 2; FIG. 6 is a cross-sectional view, taken along section line 6-6 and looking in the direction of the arrows, of the seal plate unit shown in FIG. 5; FIGS. 7 and 8 are schematic views of the pump shown in FIGS.

1 and 2, illustrating assembly of the pump.

FIG. 9 is a cross-sectional view of a front end of the pump shown in FIGS. 1 and 2 and equipped with a modified inlet connecting pipe; and FIG. 10 is a schematic view of the pump shown in FIG. 9, illustrating different orientations of the inlet connecting pipe.

Best Mode for Carrying Out the Invention FIG. 1 shows a centrifugal pump 10 constructed in accordance with the present invention. The pump 10 includes a base plate 12 and a housing 14 supported on the base plate 12. The housing 14 is provided with an inlet 16 adjacent a front end 18 thereof and an outlet 20 adjacent a rear

end 22 thereof opposite the front end 18. Each of the inlet 16 and the outlet 20 is provided with an annular projection 24 and an array of locking members 26 arranged in annular fashion on the annular projection 24. Inlet and outlet connecting pipes 28,30, each of which includes a flange 32 adjacent one end thereof, are removably coupled to the inlet 16 and the outlet 20, respectively.

Inlet and outlet union nuts 34,36 are provided for removably attaching the inlet and outlet connecting pipes 28,30, respectively, to the inlet 16 and the outlet 20, respectively. More particularly, each of the inlet and outlet union nuts 34,36 includes an annular array of locking members 38 adapted to releasably interlock with a corresponding one of the arrays of locking members 26 of the inlet 16 and the outlet 20 in bayonet fashion. In this manner, when the inlet union nut 34 is properly interlocked with the inlet 16, the flange 32 of the inlet connecting pipe 28 is securely captured between the annular projection 24 of the inlet 16 and the inlet union nut 34. Likewise, when the outlet union nut 36 is properly interlocked with the outlet 20, the flange 32 of the outlet connecting pipe 30 is securely captured between the annular projection 24 of the outlet 20 and the outlet union nut 36.

Referring to FIGS. 1 and 2, the housing 14 also includes a strainer chamber 40 positioned adjacent to the front end 18 of the housing 14 and communicating with the inlet 16 for receiving fluid therefrom. A strainer opening 42 is formed in the housing 14 at a top end of the strainer chamber

40, while a strainer basket 44 (not shown in FIG. 2) is mounted in the stainer chamber 40 through the strainer opening 42. The strainer opening 42 is defined by a cylindrical projection 46 which extends upwardly from the housing 14 and which has locking members 48 formed thereon in annular fashion. A cover 50 closes off the strainer opening 42 in a fluid-tight manner.

More particularly, a cover lock ring 52 is removably mounted to the housing 14 for securing the cover 50 to the cylindrical projection 46. In this regard, the cover lock ring 52 includes an annular array of locking members 54 sized and shaped so as to releasably interlock with the locking members 48 of the cylindrical projection 46 in bayonet fashion.

Still referring to FIGS. 1 and 2, the housing 14 is provided with a pump chamber 56 extending from the rear end 22 towards the front end 18 and terminating at the strainer chamber 40. More particularly, the pump chamber 56 is defined by an inner wall surface 58 (see FIGS. 7 and 8) of the housing 14. A vertical wall 60 separates the pump chamber 56 from the strainer chamber 40 and has a port 62 therein for allowing flow of fluid from the strainer chamber 40 to the pump chamber 56. The port 62 is provided with a collar 64 projecting from the vertical wall 60 towards the rear end 22 of the housing 14 for purposes to be discussed hereinafter.

The rear end 22 of the housing 14 is open such that various internal components of the pump 10 to be discussed hereinafter can be

removably mounted in the pump chamber 56 through the rear end 22 (see FIG. 2). The rear end 22 has an internal annular ledge 66 (see FIGS. 2,7 and 8) and an annular array of exterior locking members 68 (see FIGS. 1 and 2). The rear end 22 is also provide with a keyway 70 (see FIGS. 2,7 and 8).

The housing 14 has a pair of drain holes 72, one of which communicates with the strainer chamber 40 and the other of which communicates with the pump chamber 56. The pump 10 is also provided with a pair of spigots 74, each of which is adapted for plugging a corresponding one of the drain holes 72 in a fluid-tight manner.

Referring back to FIGS. 1 and 2, the base plate 12 has a cradle 76. More particularly, the cradle 76 extends upwardly from an end of the base plate 12 remote from the housing 14.

The pump 10 also includes an electrical motor 78 (see FIGS. 1 and 2) which has a rotatable shaft 80 and which is supported on the cradle 76 of the base plate 12. A motor mounting plate 82 is removably attached to an end of the motor 78 adjacent the shaft 80 via a plurality of bolts, while a motor lock ring 84 is removably mounted to the rear end 22 of the housing 14 for securing the motor mounting plate 82 and hence the motor 78 to the housing 14 in removable fashion. The motor lock ring 84 includes an annular array of locking members 86 sized and shaped so as to releasably interlock with the locking members 68 of the housing 14 in bayonet fashion such that the motor

mounting plate 82 can be releasably captured between the rear end 22 of the housing 14 and the motor lock ring 84. The motor lock ring 84 also has a handle 88 projecting therefrom for facilitating mounting and dismounting of the motor lock ring 84 to and from the housing 14. Referring to FIGS. 1,2,7 and 8, the motor mounting plate 82 is provided with a key 90 and a keyway 92.

The key 90 is sized and shaped so as to be received in the keyway 70 (see FIG. 2) of the housing 14 for the purpose of facilitating proper alignment of the motor mounting plate 82 with the rear end 22 of the housing 14.

Referring now to FIGS. 1-4, the pump 10 includes a diffuser 94 removably mounted in the pump chamber 56 of the housing 14. More particularly, the diffuser 94, which has an unitary construction, includes a funnel 96 provided with an inlet end 98 and an outlet end 100 opposite the inlet end 98. The funnel 96 has a frustum-conical shape (i. e., the diameter of the inlet end 98 is greater than that of the outlet end 100). Because of its shape, the funnel 96 is adapted to create a venturi effect for optimizing the flow path therethrough, thereby reducing the overall operating noise of the pump 10. The inlet end 98 is sized and shaped so as to be received in the port 62 of the vertical wall 60. In this regard, the inlet end 98 has a flange 102 extending radially outwardly therefrom and sized and shaped so as to be fitted in the collar 64. A sealing ring 104 is positioned between the vertical wall 60 and the flange 102 for performing a sealing function.

Still referring FIGS. 1-4, the diffuser 94 has a diffuser section 106 integrally connected to the outlet end 100 of the funnel 96. The diffuser section 106 has a tubular extension 108 projecting in an axial direction (i. e., in a direction parallel to the longitudinal axis of the housing 14) from the outlet end 100 of the funnel 96 towards the rear end 22 of the housing 14. An annular plate 110 extends radially outwardly from an end of the tubular extension 108 opposite the outlet end 100 of the funnel 96. The diffuser section 106 is also provided with an array of diffuser vanes 112 axially projecting from an outer periphery of the annular plate 110 in the axial direction away from the outlet end 100 of the funnel 96. The diffuser vanes 112 are sized and shaped in such a manner that they function to reduce the velocity of fluid discharged thereto. The diffuser vanes 112 define a mounting space 114 therebetween which has an open axial end 116 opposite the annular plate 110. Each of the diffuser vanes 112 includes a finger 118 extending therefrom in the axial direction away from the outlet end 100 of the funnel 96 for purposes to be discussed hereinafter.

Referring back to FIGS. 1 and 2, an impeller 120 is removably mounted in the pump chamber 56. More particularly, the impeller 120, which is mounted on an end of the shaft 80 of the motor 78, is rotatably received in the mounting space 114 of the diffuser 94 through the open axial end 116.

The impeller 120 has an inlet tube 122 for receiving fluid from the outlet end

100 of the funnel 96. The inlet tube 122 is sized and shaped so as to be rotatably received in the tubular extension 108 of the diffuser 94. A conventional wear ring 124 is positioned between the tubular extension 108 and the inlet tube 122. The impeller 120 also has a plurality of channels 126 therein for discharging high-velocity fluid to the diffuser vanes 112, which annularly surrounds the impeller 120.

Referring now to FIGS. 1,2,5 and 6, a seal plate unit 128 is removably mounted in the pump chamber 56 of the housing 14 through the rear end 22. The seal plate unit 128 has a seal plate 130 and a volute wall 132 integrally formed with the seal plate 130. The volute wall 132 extends axially from the seal plate 130 towards the front end 18 of the housing 14.

More particularly, the volute wall 132 extends into the pump chamber 56 and cooperates with the seal plate 130 to define a volute chamber 134. The volute chamber 134 has an open axial end 136 opposite the seal plate 130 for receiving the diffuser section 106 of the diffuser 94 and the impeller 120 therethrough. The volute wall 132 has a top portion 138 and a bottom portion 140 which are adapted to engage top and bottom portions 142,144 (see FIGS. 7 and 8), respectively, of the inner surface 58 of the housing 14. The top and bottom portions 138,140 of the volute wall 132 function as a guide for the seal plate unit 128 and the various components of the pump 10 connected thereto (e. g., the diffuser 94) during their insertion into the pump

chamber 56 as will be discussed further hereinbelow. An outlet port 146, which communicates with the volute chamber 134, is formed in the top portion 138 of the volute wall 132 for discharging fluid conveyed from the diffuser 94 to the outlet 20 of the housing 14.

Still referring to FIGS. 1,2,5 and 6, the seal plate 130 is sized and shaped so as to close off the rear end 22 and hence the pump chamber 56 of the housing 14 in a fluid-tight manner. More particularly, the seal plate 130 is received in the rear end 22 of the housing 14 and has an outer periphery 148 adapted to abut against the internal annular ledge 66 of the housing 14. A sealing ring 150 is positioned between the outer periphery 148 and the internal annular ledge 66 for providing fluid-tight engagement between the housing 14 and the seal plate 130. The seal plate 130 is removably secured in the rear end 22 by the motor mounting plate 82 and the motor lock ring 84. That is, the motor mounting plate 82, which is attached to the housing 14 by the motor lock ring 84, retains the seal plate 130 in the rear end 22 of the housing 14. The seal plate 130 also includes a hole 152 through which the shaft 80 of the motor 78 extends. A bushing 154 is mounted in the hole 152 for facilitating rotation of the shaft 80 and hence the impeller 120. A key 156 is also formed at an upper end of the seal plate 130, being sized and shaped so as to be received in the keyway 92 of the motor mounting plate 82.

Referring to FIGS. 2,5 and 6, the seal plate 130 has an annular ridge 158 projecting axially towards the front end 18 of the housing 14 and sized and shaped so as to substantially close off the open axial end 116 of the diffuser 94. As a result, the impeller 120 is axially interposed between the annular plate 110 of the diffuser 94 and the seal plate 130. That is, the impeller 120 is placed in a space defined by the annular plate 110, the diffuser vanes 112 and the seal plate 130. The annular ridge 158 is sized and shaped so as to be releasably gripped by the fingers 118 of the diffuser 94 for maintaining proper orientation between the diffuser 94 and the seal plate unit 128. More particularly, the fingers 118 grip an outer periphery of the annular ridge 158 therebetween by friction fit and inhibit the seal plate unit 128 from moving radially (i. e., in a direction transverse to the longitudinal axis of the housing 14) and/or axially relative to the diffuser 94.

With reference to FIG. 7, in order to assemble the pump 10, a pre-assembly unit 160 is formed by assembling the motor 78, the motor mounting plate 82, the seal plate unit 128, the diffuser 94 and the impeller 120 with one another outside the housing 14. More particularly, after attaching the motor mounting plate 82 to the motor 78, the seal plate unit 128 is placed adjacent to the motor mounting plate 82 in abutting fashion. After mounting the impeller 120 on the shaft 80 of the motor 78 in the volute chamber 134, the diffuser 94 is mounted in the volute chamber 134 through the open axial

end 136 of the seal plate unit 128. More particularly, the fingers 118 of the diffuser 94 are caused to grip the annular ridge 158 of the seal plate unit 128.

The seal plate unit 128 is then aligned with the motor mounting plate 82 by positioning the key 156 of the seal plate unit 128 in the keyway 92 of the motor mounting plate 82.

After forming the pre-assembly unit 160, it is mounted to the housing 14. More particularly, with the seal plate unit 128 and the motor mounting plate 82 held together by the user's hands, the diffuser 94 is inserted into the pump chamber 56 of the housing 14 through the rear end 22, while the motor 78 is placed on the cradle 76 of the base plate 12 (see FIG.

8). In this regard, it should be noted that the cradle 76 is provided with a predetermined height such that the inlet end 98 of the diffuser 94 is substantially aligned with the port 62 of the vertical wall 60 in automatic fashion when the pre-assembly unit 160 is placed on the cradle 76. As a result, the inlet end 98 of the diffuser 94 is properly placed in the port 62 by simply pushing the pre-assembly unit 160 towards the front end 18 of the housing 14 (as indicated by arrow A in FIG. 8). As the pre-assembly unit 160 is pushed towards the front end 18, the top and bottom portions 138,140 of the volute wall 132 engage the top and bottom portions 142,144, respectively, of the inner surface 58 of the housing 14 so as to guide the seal

plate unit 128 and hence the diffuser 94 to their proper positions in the pump chamber 56.

After the diffuser 94 and the seal plate unit 128 have been properly positioned in the pump chamber 56, the motor mounting plate 82 and hence the seal plate unit 128 are aligned with the rear end 22 of the housing 14 by placing the key 90 of the motor mounting plate 82 in the keyway 70 of the rear end 22 (see FIG. 2). The motor lock ring 84 is then applied to the rear end 22 for securing the motor mounting plate 82 and hence the pre- assembly unit 160 to the housing 14.

In order to remove the diffuser 94 and the seal plate unit 128 from the pump chamber 56, after detaching the motor lock ring 84 from the housing 14, the diffuser 94 and the seal plate unit 128 are pulled out from the housing 14 along with the pump 78 and the motor mounting ring 82. More particularly, because the diffuser 94 and the seal plate unit 128 are coupled to each other by the fingers 118 and the annular ridge 158, the diffuser 94 is removed from the pump chamber 56 along with the seal plate unit 128.

It should be appreciated that the present invention provides numerous advantages over the prior art discussed above. For instance, because the diffuser 94 and the seal plate unit 128 are formed as separate and independent units, they are adapted for selective and independent replacement. In this regard, it should be noted that the pump chamber 56 of

the housing 14 has an axial depth (i. e., a depth measured in the axial direction) adapted to accomodate diffusers and seal plate units having different specifications (i. e., sizes). As a result, the diffuser 94 and the seal plate unit 128 can be replaced with such diffusers and seal plate units so as to accomodate changing operational requirements. For example, in order to increase the pumping capacity of the pump 10, the diffuser 94 and/or the seal plate unit 128 can selectively and independently replaced with a diffuser having a larger mounting space (i. e., having a mounting space with an axial depth greater than that of the diffuser 94) and a seal plate unit having a larger volute chamber (e. g., having a volute wall with an axial depth greater than that of the volute wall 132 of the seal plate unit 128), respectively. In this manner, the pumping capacity of the pump 10 can be easily increased or decreased to suit changing operational requirements and/or user preference without replacing the housing 14.

It should also be appreciated that the pump 10 is provided with a construction that allows its quick and easy assembly and disassembly. For instance, because various components of the pump 10 (e. g., the diffuser 94, the impeller 120 and the seal plate unit 128) are designed for quick and easy pre-assembly outside of the housing 14, they facilitate assembly of the pump 10. For example, the diffuser 94 is adapted to be pre-assembled with the seal plate unit 128 in a quick and efficient manner, thereby facilitating the

formation of the pre-assembly unit 160. Moreover, because the motor lock ring 84 is designed to secure the pre-assembly unit 160 to the housing 14 in bayonet (i. e., quick-release) fashion, it allows the pre-assembly unit 160 to be quickly and easily removed from the housing 14 for inspection and/or replacement of various internal components of the pump 10. Further, because of the cradle 76, the diffuser 94, as well as the seal plate unit 128, can be properly positioned in the pump chamber 56 by simply pushing the pre-assembly unit 160 towards the front end 18 of the housing 14.

FIGS. 9 and 10 show a modified version of the inlet connecting pipe 28 shown in FIGS. 1 and 2. More particularly, an inlet connecting pipe 162 is coupled to the housing 14 in a manner identical to that of the inlet connecting pipe 28 of FIGS. 1 and 2. The inlet connecting pipe 162 includes an inlet opening 164 at one end thereof and an outlet opening 166 at an opposite end thereof. The outlet opening 166 of the inlet connecting pipe 162 is connected to the inlet 16 of the housing 14. Because the inlet connecting pipe 162 is provided with a gooseneck, the inlet opening 164 is radially offset relative to the outlet opening 166. That is, the inlet opening 164 has a central axis B which is radially spaced apart from a central axis C of the outlet opening 166. As a result, the inlet opening 164 is adapted to be selectively positioned at any one of an infinite number of vertical positions by rotating the inlet connecting pipe 162 about the inlet 16 of the housing 14 and, more

particulariy, about the central axis C of the outlet opening 166. That is, the outlet opening 166 can be selectively positioned at its bottommost vertical position (indicated by solid line representation of the inlet connecting pipe 162 in FIG. 10), its topmost vertical position (indicated by broken line representation of the inlet connecting pipe 162 in FIG. 10) or any one of an infinite number of positions between the bottommost and topmost positions.

In this manner, the inlet 16 of the housing 14 can be connected to an external pipe 168 located at a vertical position different from that of the inlet 16 of the pump 10 without adjusting the vertical position of the housing 14.

It should be noted that the present invention can have numerous modifications and variations. For instance, the fingers 118 of the diffuser 94 can be replaced with other mechanisms (e. g., a threaded or snap-fit connector) for removably attaching the diffuser 94 to the seal plate unit 128.

Moreover, the outlet connecting pipe 30 can be replaced with an outlet connecting pipe similar to the inlet connecting pipe 162 shown in FIGS. 9 and 10. In addition, bayonet-type mechanisms can be provided on the motor 78 and the motor mounting plate 82 for removably connecting them to one another.

It will be understood that the embodiment described herein is merely exemplary and that a person skilled in the art may make many variations and modifications without departing from the spirit and scope of the invention. All such variations and modifications are intended to be included within the scope of the invention as defined in the appended claims.