JPS646356B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multi-stage pump, particularly to a pump structure.

FIG. 1 shows the structure of a conventionally proposed multistage pump, particularly a cantilever type multistage pump. The multistage pump shown in Fig. 1 has impellers 1 and 2 of the same diameter arranged on the same rotating shaft 3 facing the same direction. A volute chamber 4 is formed on the inner surface, and a volute chamber 7 is formed on the inner surface, and a suction casing 6 with a suction port 5 and a volute chamber 7 that covers the discharge surface of the second stage (final stage side) impeller 2 are formed on the inner surface. An intermediate casing 10 is sandwiched between a discharge casing 9 having a discharge port 8 and an intermediate casing 10 that guides water discharged from the first stage impeller 1 through the volute chamber 4 to the suction port of the second stage impeller 2. It is an accumulation of.
To explain further, the suction casing 6, the intermediate casing 10, and the discharge casing 9 are assembled together by tightening the bolt seats provided in the suction casing 6 and the discharge casing 9, respectively. Reference numeral 11 denotes a connecting bracket which connects the electric motor 12 and the discharge casing 9. At the lower part of this connecting bracket 11, legs 14 are provided for attaching and fixing to the bed 13.

In the multistage pump configured in this way, the electric motor 12
During the operation, the water sucked into the suction casing 6 through the suction port 5 is pressurized by the first stage impeller 1, and then pumped into the second stage by the intermediate casing 10.
The air is guided to the impeller 2 in the third stage, where the pressure is increased again, and then it is discharged from the discharge port of the discharge casing 9 to the outside of the discharge casing 9.

Now, in such a multistage pump, disassemble the multistage pump while leaving the piping in each casing,
In recent years, it has been said that it is necessary to perform maintenance on this. However, in the multistage pump having the structure explained in FIG. Because they are not integrated with casings 6 and 9, each casing 6 and
There are many disadvantages such as the inability to support the pipes connected to 9.

In order to solve this problem, recently, the pump casing has a suction flange and a discharge flange with a suction port and a discharge port connected to the piping, and also a foot for attaching to the bed. A multistage pump having a structure in which two impellers are arranged back to back and an intermediate casing is arranged between these impellers has been proposed in U.S. Pat. However, the arrangement in which the impellers are arranged back to back has the disadvantage that the structure of the interstage passage connecting the two impellers is complicated.

Therefore, in order to make the structure of the inter-stage passage relatively simple, a method in which the impellers are arranged in the same direction was also proposed.
No. 52-81701. However, even if such a structure is adopted, parts with a complicated structure still remain, and a proposal for a multistage pump with a further improved structure has been desired.

In particular, in such pumps, most of the main parts are made of cast products, so the most important issue is that each part has a simple structure and one that allows for easy casting work. becomes.

Therefore, the present invention provides a multistage pump with a new structure that allows maintenance to be performed with the piping connected, and also facilitates the manufacture of each part.

That is, the present invention includes a rotating shaft, an impeller having a suction port facing the same direction on the rotating shaft, a small diameter impeller on the front stage side, and a large diameter impeller on the final stage side,
A pump casing that houses these impellers, has a suction flange with a suction port, a discharge flange with a discharge port, and has an opening that opens the rear shroud side of the impeller on the final stage side. In a multi-stage pump equipped with a casing cover that closes an opening, a volute surface that is housed in the pump casing and faces the entire circumference of the discharge surface of the impeller that constitutes the volute chamber of the impeller on the front stage side, and a volute surface on the final stage side. a volute surface that faces approximately half the circumference of the discharge surface of the impeller constituting the volute chamber of the impeller; and a water return passageway that guides the discharge flow of the impeller on the preceding stage to the suction port of the impeller on the final stage. and a pump casing having a volute surface constituting a volute chamber following the volute surface constituting the volute chamber of the impeller on the final stage side of the intermediate casing, and fitting with the outer peripheral surface of the intermediate casing. The present invention provides a multi-stage pump with the following features.

Embodiments of the present invention will be described below with reference to FIGS. 2 and 3. FIG. 2 is a partial cross-sectional view showing a two-stage cantilever pump directly connected to an electric motor according to an embodiment, and FIG. 3 is a partial cross-sectional view showing an enlarged main part of FIG. 2. To explain this, 15 is a pump casing having a cylindrical shape as a whole, a suction flange 55 having a suction port 16 at the center of one end surface of the cylinder, and an opening 1 with an open end surface facing the suction port 16.
7. Outlet 18 on the opening 17 side at the top of the cylinder surface
A discharge flange 53 with a cylindrical surface is provided with legs 21 at the bottom of the cylindrical surface for installation on the bed 20. Further, the pump casing 15 has an inner wall whose inner diameter gradually increases from the suction side toward the opening 17, and is integrally constructed. 22 and 23 are impellers that are attached to a rotating shaft 26 that extends from the motor 25 side with the sleeve 24 in between, with the suction ports facing in the same direction. The diameter of the first impeller 23 (on the final stage side) is configured to be large. 27 is the pump casing 15
This is an intermediate casing that is housed in the inner casing, and this intermediate casing is the discharge surface 22c of the first stage impeller 22.
It has an inner wall surface that faces the entire circumference of the impeller 22, and forms a part of the volute chamber 28 of this impeller 22, and also has an inner wall surface that faces the entire circumference of the impeller 22.
The impeller 23 has inner wall surfaces facing each other over approximately half the circumference of the impeller 23, and constitutes a part of the volute chamber 29 of the impeller 23. Further, the intermediate casing 27 has a water return passage 30 that guides water discharged from the first stage volute chamber 28 to the suction port of the second stage impeller 23.
Equipped with. The structure of the intermediate casing 27 will be further explained with reference to FIG.
The front side 27a (first stage impeller 22 side) is 1
It covers the entire circumference of the discharge surface 22c of the impeller 22 in the first stage and the rear shroud side 22d, and constitutes a part of the volute chamber 28 of the impeller 22 in the first stage. The front shroud 22b side of the impeller 22 is surrounded by the inner wall surface of the pump casing 15, and the end surface 27b of the front side 27a of the intermediate casing 27 is attached to this inner wall surface.
By abutting against each other, the volute chamber 28 of the impeller 22 is completed. The rear surface side 27c (second-stage impeller 23 side) of the intermediate casing 27 covers approximately half the circumference of the discharge surface 23c of the second-stage impeller 23 and the front shroud 23b, and covers the volute chamber 29 of the second-stage impeller 23. constitute a part. Then, by covering the rear shroud 23d side of the impeller 23 with a casing cover 40, which will be described later, the impeller 23 is
The third volute chamber 29 is completed. Reference numeral 31 indicates a water return blade provided between the front and rear surfaces 27a and 27c of the intermediate casing 27. This is for efficiently guiding water to the suction port 23a of the second stage impeller 23. That is, the water flowing from the first stage volute chamber 28 into the water return passage 30a on the front side 27c side of the intermediate casing 27 flows through the front and rear sides 27a, 2.
After passing through the water return passage 30b provided between the
It is supplied to the suction port 23a of No. 3. In addition, 3
4, 35, 35, and 37 are liner rings, which are respectively arranged on the inner wall surface of the pump casing 15, the inner diameter end of the front side 27a of the intermediate casing 27, the inner diameter end of the rear surface side 27c of the intermediate casing 27, and the inner wall surface of the end cover 40. Installed on the first stage impeller 22
, the mouth portion of the first stage impeller 22 near the rotation axis on the rear shroud 22d side, the mouth portion of the second stage impeller 23, and the back mouth portion of the second stage impeller 23. Further, a pilot face 32 is provided at the outermost diameter portion of the intermediate casing 27, and the pilot face 32 is connected to the inner wall through the opening 17 provided on the rear shroud 23d side of the second stage impeller of the pump casing 15. Inro surface 33 to be stretched along
It fits into the Reference numeral 38 designates a connecting ring that fits and attaches to the opening 17 of the pump casing 15, including a first contact surface 38a that contacts the end surface 17a of the opening 17 of the pump casing 15, and an end surface of the rear surface side 27c of the intermediate casing 27. A second abutting surface 38b that abuts with 27d is provided. Further, this connection ring 38 is provided with a third contact surface 38c and a pilot surface 38d for a casing cover 40 attached to close the rear shroud 23d side of the second stage impeller 23. 38e is a screw hole provided in the second contact surface 38b, and a bolt 39 is screwed into this screw hole 38e through a through hole 27e provided in the rear surface side 27c of the intermediate casing 27. 38f is a screw hole provided on the third contact surface 38c side, and this screw hole 38f has a through hole 41 formed in a bolt seat 41 provided in the casing cover 40.
A bolt 42 is screwed through a. Further, a bolt seat 43 is provided on the outer cylindrical surface of the connecting ring 38. This connecting ring 38 passes through a through hole 43a provided in a bolt seat 43, and the bolt 45 is inserted into a screw hole 44a of a bolt seat 44 provided in the pump casing 15.
It is fixed to the opening 17 of the pump casing 15 by screwing it into the opening 17 of the pump casing 15. The casing cover 40 is provided with a through hole 46 in the center thereof through which the rotating shaft 26 passes, and further includes a mating surface 40a and a fitting surface 40b for fitting with the connecting ring 38. 47 is the through hole 4 of the casing cover 40
6 and the rear shroud 23d of the second stage impeller 23
A shaft sealing device, such as a mechanical seal, is placed between the shaft and the shaft. Further, one side of the casing cover 40 constitutes a connection frame 49 which also serves as an end bracket 48 of the electric motor 25.

To explain the details further, 50 is an air vent provided on the pump casing 15 so as to communicate with the upper part of the water return passage 30, and 51 and 52 are air vent holes provided on two sides of the discharge flange 53 of the pump casing 15 for mounting gauges. Mounting hole, 54
56 and 57 are mounting holes for attaching a gauge provided in the suction flange 55, and 56 and 57 are the discharge flange 53.
Reinforcement ribs 58 and 59 are provided between the pump casing 15 and the leg 21, respectively. 6
0 is a drain hole provided in the pump casing 15 so as to communicate with the lower part of the water return passage 30, and 61 is a drain hole that is partially extended larger than the other bolt seats 44, and is between this and the bolt seat 43 of the connecting ring 38 that faces this hole. The bolt seat is provided with a thin wall portion 61a to create a slight gap in which a disassembly tool can be inserted during disassembly.

Furthermore, as shown in FIG. 5, the structure of the volute chamber 29 of the second stage impeller 23, especially the inner wall portion facing the discharge surface 23c of the impeller 23, is connected to the rear surface side 27c of the intermediate casing 27 and the pump casing 15.
This will be explained in detail since it is divided into parts on the inner wall surface. That is, the discharge surface 2 of the impeller 23 on the rear surface side 27c of the intermediate casing 27
The volute surface 27g facing the impeller 23 starts from the tongue portion 27f near the outlet 18.
It is arranged to end approximately halfway around the volute chamber 29 along the direction of rotation. After this, the inner wall surface of the pump casing 15 facing the discharge surface 23c of the impeller 23 is gradually expanded to form a volute surface 15g, which is configured to be connected to the discharge port 18. In this way, the discharge surface 23c of the impeller 23
The volute surfaces 27g and 15g facing the intermediate casing 27 and pump casing 15 respectively
If the volute chamber is divided into two parts, the outer diameter of the intermediate casing 27 can be made smaller than when the volute chamber is composed of only the intermediate casing, and the diameter of the pump can be made smaller. Moreover, when the intermediate casing 27 is made of a cast metal, the strength of the core can be increased by reducing the thin wall portion of the cast metal, and the castability can be improved.

In other words, with some explanation, it is possible to provide the volute chamber of the impeller on the final stage side on the pump casing side, but if such a structure is adopted, the entire circumference of the inner wall surface on the opening side of the pump casing It becomes necessary to provide a concave structure over a period of time, which complicates the structure of the pump casing and impairs its castability. It is also conceivable to provide all the volute chambers of the impeller on the final stage side in the intermediate casing, but this would increase the outer diameter of the intermediate casing, making it difficult to miniaturize the pump. This is because if the outer diameter of the intermediate casing is limited, there will be an extremely thin wall at the end of the volute chamber, which cannot be accommodated by cast products.In the end, in order to ensure the strength of the intermediate casing, the outer diameter becomes larger. For reference, the shape of the water return blade 31 provided in the water return flow path 30b is shown by a dotted line in FIG.

Continuing the explanation further, the pump of the embodiment can be driven by an electric motor having a structure similar to the electric motor 12 already explained in FIG. 1, but in this case, the conventional foot 14 is provided on the electric motor side. There will be no need. Now, to explain the structure of the electric motor 25 side adopted in the embodiment in FIG. 2, 62 is an air suction port provided on the end bracket 63, and 64 is an air suction port provided on the lower side of the cylindrical surface of the end bracket 48 on the connection frame 49 side. Air outlet, 65 is rotation axis 2
6 and is supported by bearings provided on end brackets 48 and 63. A stator 66 faces the rotor 65 and is housed within a rib 67 protruding from the inner surface of the housing 68 that connects the end brackets 48 and 63. 69 is a fan guide provided between the housing 68 and the end bracket 63, and 70 is a support bolt provided between the bed 20 for supporting the lower part of the housing 68 with its own head. 71 is a slinger provided on the rotating shaft 26 outside the end bracket 48 to prevent water from the pump from entering the electric motor 25 side; 72 is a vent provided in the connection frame 49.

Next, the assembly procedure of a multistage pump having this structure will be briefly explained. First, the assembly of the electric motor 25 side is well known in the art, so a description thereof will be omitted. After the connecting frame 49 is assembled to the electric motor 25 side, the connecting ring 38 is attached to the connecting frame 49 with bolts 42. Next, the shaft sealing device 47
is placed on the rotating shaft 26, and the second stage impeller 23 is keyed to the rotating shaft 26. After this, the intermediate casing 27 is fixed to the connecting ring 38 with bolts 39. Next, after the sleeve 24 is placed over the rotating shaft 26, the first stage impeller 22 is key-coupled, and the rotating shaft 26 is
6 is tightened to fix both impellers 22 and 23 to the rotating shaft 26. Finally, the pump casing 15 is placed over these assemblies, and the pump casing 15 is fixed to the connecting ring 38 with bolts 45 to complete the multi-stage pump. In addition,
The bed 20 can be fixed to the foot 21 of the pump casing 15 at the beginning or at the final stage of the assembly operation.

Now, if such a structure is adopted, when maintenance of the pump is performed after it has been installed, it is possible to maintain the pump by loosening the bolts 45 and pulling out the motor 25 part, for example, to the right in FIG. , the main parts of the multistage pump can be removed from the pump casing. These disassembly procedures are almost the opposite of the assembly procedure described above, so their explanation will be omitted. Since the multistage pump can be maintained while the piping remains on the pump casing 15 side, such a structure greatly facilitates maintenance work.

In the embodiment described, a coupling ring 38 is provided, to which the intermediate casing 27 and the coupling frame 4 are connected.
9 is connected, but this connecting ring 38
can be constructed integrally with the intermediate casing 27 or with the connecting frame 49. In the embodiment, the connection ring 38 is made as a separate member because
This is to simplify the structure of the intermediate casing 27 or the connecting frame 49. Moreover, if the connecting ring 38 is constructed as a separate member, a multistage pump with different characteristics or capacity can be obtained by simply preparing and replacing the intermediate casing 27 with another shape. Furthermore, by selecting an appropriate shape for the connecting frame, electric motors or internal combustion engines of different structures can be assembled. To change the capacity of a multi-stage pump, i.e. to reduce the capacity, it is possible to incorporate an impeller with a smaller diameter and, if necessary, to modify the inner wall to accommodate the smaller diameter impeller. An intermediate casing with smaller dimensions is prepared and assembled. At this time, a two-stage pump can be constructed by combining impellers of the same diameter and different diameters, but
When combining impellers with different diameters, it is advantageous to arrange a small diameter impeller in the first stage and a large diameter impeller in the second stage. The reason for this is that, first, impellers tend to be selected with large specific speeds in the first stage, which is the water inlet side, and impellers with small specific speeds and large diameters tend to be selected in the second stage. Assembling the car is
This is because cavitation performance is improved and characteristics are advantageous. Secondly, by reducing the diameter of the first-stage impeller and configuring the volute chamber therein to be small, it is possible to provide flexibility in the design of the water return passage placed in front of the impeller. Thirdly, by arranging a large-diameter impeller with a large amount of work on the side closer to the bearing, it is possible to reduce the vibration of the rotating shaft 26 and raise the operating speed limit. As described above, in the multistage pump of the embodiment, by simply preparing several types of replacement parts, multistage pumps having a considerable variety of characteristics and capacities can be manufactured by combining these parts.

Next, the embodiment shown in FIG. 6 will be described. This embodiment is a multi-stage pump that is coupled to a driving machine. In this embodiment, a connecting frame 76 including a bearing box 75 that supports a rotating shaft 74 is provided, and this connecting frame 76 is fixed to a casing cover 77 attached to the connecting ring 38. That is, the casing cover 77 is provided with a through hole 78 in the center through which the rotating shaft 74 passes, a packing storage portion 79 connected to the through hole 78, and a mating surface 77a for fitting and connecting with the connecting ring 38. It is provided with an inlay surface 77b. Reference numeral 80 denotes a shaft sealing device, such as a gland packing, arranged between the packing storage portion 79 and the rotating shaft 74. This gland packing 80 is pushed into the packing storage portion 79 by a packing presser 81 and stored. Bearings 82 and 83 are attached to the bearing box 75 and support the rotating shaft 74. 84
is a coupling attached to the shaft end of the rotating shaft 74, through which a driving machine such as an electric motor or an internal combustion engine is connected. 85 is an auxiliary leg for supporting the bearing box 75. The structure on the suction side of the connecting ring 38 is the same as that of the previously described embodiments, so a description thereof will be omitted.

In the embodiments described above, if necessary, an O-ring or a conventionally known sealing member can be inserted between the abutting surfaces of the various members or before fitting. In the embodiment, the inner diameter of the inner wall increases from the suction side of the pump casing 15 toward the opening 17, which improves castability when it is made of cast metal. At the same time, the intermediate casing 27 can be easily assembled. Further, although the suction port 16 is provided on the end face of the cylindrical pump casing 15 in the embodiment, the suction port 16 may be arranged on the cylindrical surface, and may be of a so-called in-line type. Further, in the embodiment, a multistage pump having two stages has been described, but in the present invention, a multistage pump having three or more stages can be constructed by further stacking impellers and intermediate casings.

In this way, the present invention comprises a rotating shaft, an impeller on which the suction port is oriented in the same direction, a small diameter on the front stage side and a large diameter on the final stage, and these impellers. A pump casing that has a suction flange with a suction port, a discharge flange with a discharge port, and an opening that opens the rear shroud side of the impeller on the final stage side, and a casing that closes the opening of the pump casing. a volute face that is housed in the pump casing and faces the entire circumference of the discharge face of the impeller that constitutes the volute chamber of the impeller on the front stage side; and a volute face of the impeller on the final stage side; an intermediate casing having a volute surface facing approximately half the circumference of the discharge surface of the impeller constituting the chamber, and a water return passageway that guides the discharge flow of the impeller on the preceding stage to the suction port of the impeller on the final stage; , a multi-stage pump having a volute surface constituting a volute chamber of an impeller on the final stage side of the intermediate casing and a volute surface constituting a volute chamber following the volute surface constituting the volute chamber of the impeller on the final stage side of the intermediate casing, and a pump casing that fits with the outer peripheral surface of the intermediate casing. According to the present invention, it is possible to obtain a multistage pump that can be maintained while the piping is connected and is easy to manufacture.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional view for explaining the structure of a conventional multi-stage pump, FIG. 2 is a partial cross-sectional view for explaining the structure of one embodiment of the present invention, and FIG. 3 is a partial cross-sectional view for explaining the structure of an embodiment of the present invention. 4 is a partial sectional view further illustrating the essential parts of FIG. 3, and FIG. 5 is a schematic diagram showing the AA cross section of FIG. 3. FIG. 6 is a partially sectional view showing another embodiment of the present invention. 15... Pump casing, 15g... Volute surface of pump casing, 16... Suction port, 17... Opening, 18... Outlet port, 2
2, 23... Impeller, 22a, 23a... Suction port of impeller, 22c, 23c... Discharge surface of impeller, 23d... Rear shroud of impeller on final stage side, 26... Rotating shaft, 27 ...Intermediate casing, 27g...Volume surface of intermediate casing,
28, 29... Volute chamber, 40, 77... Casing cover, 53... Discharge flange, 5
5...Suction flange.

Claims (1)

[Scope of Claims] 1. A rotating shaft, an impeller with suction ports facing the same direction on the rotating shaft, small diameter ones on the front stage side and large diameter ones on the final stage side, and these impellers. A pump casing that has a suction flange with a suction port, a discharge flange with a discharge port, and an opening that opens the rear shroud side of the impeller on the final stage side, and a casing that closes the opening of the pump casing. a volute surface that is housed in the pump casing and faces the entire circumference of the discharge surface of the impeller that constitutes the volute chamber of the impeller on the front stage side, and an impeller on the final stage side; a volute surface facing approximately half the circumference of the discharge surface of the impeller constituting the volute chamber of the vehicle; and a water return passage that guides the discharge flow of the impeller on the front stage side to the suction port of the impeller on the final stage side. an intermediate casing having a volute surface constituting a volute chamber of the impeller on the final stage side of the intermediate casing; A multistage pump characterized by comprising a casing.