JP4503283B2 - Casing and multistage pump equipped with the casing - Google Patents

Description

  The present invention relates to a casing and a multistage pump, and particularly to a casing manufactured by casting and a multistage pump including the casing.

  Conventionally, a multistage pump has been widely used as a fluid machine for transferring a liquid. The multistage pump includes a plurality of impellers arranged along a drive shaft and a casing that accommodates the impeller. When these impellers are rotated, the liquid introduced from the suction port is boosted. And discharged from the discharge port. This type of multistage pump is disclosed in, for example, Patent Documents 1 and 2.

  FIG. 1 is a cross-sectional view showing the structure of a conventional multistage pump. As shown in FIG. 1, the casing 5 includes a suction casing 1, an intermediate casing 2, and a discharge casing 3. The suction casing 1 has a suction port (not shown) for introducing liquid into the casing 5, and the discharge casing 3 has a discharge port 3d for discharging the liquid in the casing 5 to the outside. Yes. A plurality of impellers 4 fixed to the drive shaft 7 are accommodated in the casing, and these impellers 4 are rotationally driven via the drive shaft 7 by a drive source (not shown).

  The fluid discharged from the first stage impeller 4 passes through the volute passage 2a formed inside the intermediate casing 2, and further passes through the return passage 2b formed inside the intermediate casing 2, to the second stage. It is guided to the impeller inlet 4 a of the impeller 4. Inside the discharge casing 3, a volute passage 3 a and a discharge passage 3 b are integrally formed in the same manner as the intermediate casing 2.

  In such a casing structure, the volute passage 2 a and the return passage 2 b are integrally formed inside the intermediate casing 2, and the volute passage 3 a and the discharge passage 3 b are integrally formed inside the discharge casing 3. For this reason, the internal shape of the casing 5 becomes complicated. In particular, sufficient molten metal (hereinafter referred to as “hot water”) is supplied in the vicinity of the partition wall 2c that partitions the volute passage 2a and the return passage 2b and the partition wall 3c that partitions the volute passage 3a and the discharge passage 3b. This is a major cause of casting defects. In particular, a material such as stainless steel having poor fluidity of hot water has a problem that it is difficult to form the casing 5 by casting.

Japanese Patent Laid-Open No. 11-324964 JP 2003-184778 A

  The present invention has been made to solve the above-described conventional problems, and includes a casing that can be molded without causing casting defects even with a material having poor fluidity of hot water such as stainless steel, and the casing. An object is to provide a multi-stage pump provided.

In order to solve the above-described problems, one aspect of the present invention is a casing for a multistage pump that houses a plurality of impellers arranged along a drive shaft, and the casing is liquid by rotation of the impeller. A suction casing and a guide casing, each of which is integrally formed with guide vanes for converting the velocity energy applied to the pressure, and the liquid guided by the guide vanes to the impeller inlet of the next stage impeller The return vane is integrally formed with a return casing and a discharge casing having a discharge port. The suction casing and the guide casing are formed separately from the return casing, and the guide vane and the return vane to either one of, the partitions the return passage formed between the back vanes and the guide path formed between the guide vanes The partition wall integrally molded, characterized in that the end of the other axial direction of said guide vanes and the return blades in contact with the partition wall.

  Another aspect of the present invention is a multi-stage pump including a plurality of impellers, a drive shaft to which the impeller is fixed, and the casing.

  According to the present invention, the guide passage and the return passage that are conventionally formed in one intermediate casing are divided and formed inside the suction casing and the return casing, or the guide casing and the return casing, respectively. The structure of can be simplified. As a result, the hot water is smoothly supplied during casting, and even a material such as stainless steel having poor fluidity of the hot water can be molded without causing casting defects.

Hereinafter, a multistage pump according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 2 is a cross-sectional view showing a multistage pump according to an embodiment of the present invention. As shown in FIG. 2, the multistage pump includes a plurality of (three stages in the present embodiment) impellers 4 fixed to the drive shaft 7 and a casing 5 that houses these impellers 4. . The drive shaft 7 is connected to an electric motor 30 as a drive source, and the impeller 4 is rotationally driven by the electric motor 30 via the drive shaft 7.

  The casing 5 includes a suction casing 11, a return casing 13, a guide casing 12, and a discharge casing 14, which are fixed to each other by bolts 25 and nuts 26. The suction casing 11 has a suction port 11 a that opens in the axial direction of the drive shaft 7, and liquid is introduced into the casing 5 from the suction port 11 a. The discharge casing 14 has a discharge port 14a that opens radially outward, and the liquid in the casing 5 is discharged to the outside via the discharge port 14a.

  When the impeller 4 is rotated by the electric motor 30, the liquid is sucked into the casing 5 from the suction port 11a, and after being pressurized by the impeller 4 at each stage, is discharged to the outside from the discharge port 14a. A shaft seal device 31 for preventing the pressurized liquid from entering the electric motor 30 is disposed at a portion where the drive shaft 7 discharges and penetrates the casing 14. The shaft seal device 31 is accommodated in a flange 14 b formed on the upper wall of the discharge casing 14.

  3 is a cross-sectional view showing the suction casing 11 of FIG. 2, and FIG. 4 is a cross-sectional view showing the guide casing 12 of FIG. As shown in FIGS. 3 and 4, a plurality of guides for converting velocity energy applied to the liquid by rotation of the impeller 4 (see FIG. 2) on the inner surfaces of the suction casing 11 and the guide casing 12. Each blade 16 is provided. These guide vanes 16 extend in a spiral shape, and a guide passage 21 is formed between the adjacent guide vanes 16.

  The guide vane 16 and the suction casing 11 shown in FIG. 3 are integrally formed by casting. Similarly, the guide vane 16 and the guide casing 12 shown in FIG. 4 are integrally formed by casting. In any of the suction casing 11 and the guide casing 12, the axial end 16a of the guide vane 16 is not provided with a partition wall that divides the guide passage 21, so that one end side of the guide passage 21 in the axial direction is It is open.

  FIG. 5 is a cross-sectional view showing the return casing 13 of FIG. As shown in FIG. 5, a plurality of return vanes 17 are provided on the inner surface of the return casing 13 for rectifying the liquid introduced into the impeller inlet 4 a (see FIG. 2) of the next stage impeller 4. A return passage 22 is formed between the adjacent return blades 17. A substantially disc-shaped partition wall 20 is fixed to the end portions of the return blades 17 in the axial direction, and the return passage 22 is defined by the return casing 13, the adjacent return blades 17, and the partition walls 20. . The return casing 13, the return blade 17, and the partition wall 20 are integrally formed by casting. As shown in FIG. 2, a partition wall 27 and a return blade 28 that are integrally formed with each other are disposed inside the discharge casing 14.

  FIG. 6 is a cross-sectional view showing a state in which the suction casing 11 (or the guide casing 12) and the return casing 13 are combined. As shown in FIG. 6, the suction casing 11 (or the guide casing 12) and the return casing 13 are fixed to each other in a state of being arranged along the axial direction (the direction in which the drive shaft 7 extends). The partition wall 20 provided in the return casing 13 abuts on the end 16 a of the guide vane 16, whereby the guide passage 21 is defined by the suction casing 11 (or the guide casing 12), the adjacent guide vane 16, and the partition wall 20. Made.

  In the conventional casing structure, the guide passage and the return passage are integrally formed in one intermediate casing. However, in this embodiment, the guide passage 21 is formed on the suction casing side (or the guide casing side) and the return passage is formed. A passage 22 is formed on the return casing side. Thus, the structure of the casing 5 can be simplified by dividing the guide passage 21 and the return passage 22. As a result, the hot water is smoothly supplied during casting, and the casing 5 can be formed without causing casting defects even if the material is stainless steel or the like having poor hot fluidity.

  In the present embodiment, the partition wall 20 is formed integrally with the return blade 17 of the return casing 13, but the partition wall 20 may be formed integrally with the suction casing 11 and the guide blade 16 of the guide casing 12. Even in this case, the guide passage 21 can be formed on the suction casing side (or the guide casing side), and the return passage 22 can be formed on the return casing side. Thereby, the structure of a casing can be simplified and it becomes possible to shape | mold a casing, without producing a casting defect.

It is sectional drawing which shows the structure of the conventional multistage pump. It is sectional drawing which shows the multistage pump which concerns on one Embodiment of this invention. It is sectional drawing which shows the suction casing of FIG. It is sectional drawing which shows the guide casing of FIG. It is sectional drawing which shows the return casing of FIG. It is sectional drawing which shows the state which combined the suction casing (or guide casing) and the return casing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Suction casing 2 Intermediate casing 3 Discharge casing 4 Impeller 5 Casing 7 Drive shaft 11 Suction casing 12 Guide casing 13 Return casing 14 Discharge casing 16 Guide vanes 17 and 28 Return vanes 20 and 27 Partition 21 Guide passage 22 Return passage 25 Bolt 26 Nut 30 Electric motor 31 Shaft seal device

Claims (2)

A casing for a multi-stage pump that houses a plurality of impellers arranged along a drive shaft,
The casing includes a suction casing and a guide casing, each of which is integrally formed with guide vanes for converting velocity energy imparted to the liquid by rotation of the impeller into pressure,
A return casing integrally formed with return vanes for guiding the liquid guided by the guide vanes to the impeller inlet of the next stage impeller;
A discharge casing having a discharge port;
The suction casing and the guide casing are formed separately from the return casing,
To either one of said guide vanes and said return vanes, a partition wall for partitioning a return passage formed between the back vanes and the guide path formed between the guide vanes formed integrally,
A casing for a multistage pump , characterized in that the other axial end of the guide vane and the return vane is in contact with the partition wall . Multiple impellers,
A drive shaft to which the impeller is fixed;
A multi-stage pump comprising the casing according to claim 1.

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