JP2008095649A - Multistage diffuser pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multistage diffuser pump capable of reducing noise without deteriorating pump efficiency. <P>SOLUTION: The multistage diffuser pump comprises an impeller 5 mounted to a rotary shaft 4 in an axial direction in multi stages, a cylindrical casing 8 for forming a flow passage to the impeller 5, a guide vane 6 for guiding fluid flowing from the outer periphery of the impeller 5 outward, a return vane 7 for guiding the fluid flowing from the outer periphery of the guide vane 6 to an inner periphery side, and a disk-shaped partition 9 for partitioning the flow passage of the guide vane 6 and the flow passage of the return vane 7. The disk-shaped partition 9 is arranged so as to move within a minute range in an axial direction with respect to the cylindrical casing 8. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a multistage diffuser pump, and is particularly suitable for a multistage diffuser pump provided with a disk-like partition that partitions a guide vane flow path and a return vane flow path.

  As a technique for reducing the vibration noise of the multistage diffuser pump, reducing the fluid excitation force acting on the casing can be mentioned. As a method of reducing the fluid excitation force, a method of reducing vibration noise by increasing the gap between the exit of the impeller and the entrance of the guide vane (conventional technique 1), or skewing the impeller exit in three dimensions. A technique (prior art 2) is known that reduces vibration noise by twisting, relieving interference between guide vanes and impellers.

  Further, as another method for reducing the fluid excitation force, as disclosed in Japanese Patent Laid-Open No. 5-14120 (Patent Document 1), a method of reducing vibration noise by shifting the blade pitch of the impeller. (Prior Art 3).

Japanese Patent Publication No. 5-14120

  However, in the prior arts 1 and 2 described above, the fluid excitation force that causes the multistage diffuser pump to vibrate is reduced, and if the vibration noise is greatly reduced, the pump efficiency decreases. was there. That is, in the prior art 1, when the gap between the guide vane inlet and the impeller outlet is increased, vibration noise can be reduced, but the pump efficiency may be reduced. Moreover, in the prior art 2, if the impeller outlet is excessively skewed three-dimensionally, the pump efficiency may be lowered.

  Further, in the prior art 3, the radial fluid excitation force that causes the multistage diffuser pump to vibrate is reduced, and no consideration is given to reducing the axial fluid excitation force.

  The inventors of the present invention conducted a fluid-structure interaction analysis of the multistage diffuser pump, and it was not the radial fluid excitation force but the axial fluid excitation force that most affected the noise. I understood that. That is, a turbulent flow is generated in the fluid flowing out from the outer peripheral end face opening of the impeller 5, and this turbulent flow flows so as to cover the disc-shaped partition 9 sandwiched between the guide vane 6 and the return vane 7. Therefore, it is understood that a non-uniform pressure difference is generated in the axial direction with the disk-shaped partition 9 as a boundary, and a large axial fluid excitation force is generated on the disk-shaped partition 9 due to the non-uniform pressure difference. It was.

  However, in the conventional general multi-stage diffuser pump, the side plate, the guide vane, the disc-shaped partition and the return vane are integrally formed to form a vane assembly, and this vane assembly is centered. The side plate of the assembly and the cylindrical casing were joined. For this reason, the disk-shaped partition is restrained in the axial direction with respect to the cylindrical casing, and the large axial fluid excitation force generated in the disk-shaped partition is directly transmitted to the cylindrical casing, causing the cylindrical casing to vibrate and generating large noise. Had occurred.

  An object of the present invention is to provide a multi-stage diffuser pump capable of reducing noise without reducing pump efficiency.

  In order to achieve the above-described object, the present invention provides an impeller mounted in multiple stages in the axial direction on a rotating shaft, a cylindrical casing forming a flow path to the impeller, and an outer periphery of the impeller. Guide vanes that guide the fluid flowing outward, return vanes that guide the fluid flowing out from the outer circumference of the guide vanes to the inner circumference, and a disc that partitions the guide vane channel and the return vane channel In the multistage diffuser pump provided with a partition, the disk-shaped partition is configured to be installed so as to be movable in a small range in the axial direction with respect to the cylindrical casing.

A more preferable specific configuration example of the present invention is as follows.
(1) The cylindrical casing is divided into a plurality corresponding to each stage of the impeller, and the divided cylindrical casing, the return vane, and the guide vane are configured as a casing assembly formed integrally. The disk-shaped partition is installed between the casing assemblies independently with a minute gap in the axial direction.
(2) The divided cylindrical casing has a cylindrical wall and a partition wall, and the return blade and the guide blade are integrally formed on both sides of the partition wall of the divided cylindrical casing, and the disk-shaped partition Is installed with a small gap in the axial direction independently between one return blade and the other guide blade of the adjacent casing assembly.
(3) Provided with means for preventing rotation of the disk-shaped partition in the circumferential direction.
(4) Means for preventing radial movement of the disk-shaped partition was provided.
(5) Means for preventing rotation of the disk-shaped partition in the circumferential direction and means for blocking radial movement of the disk-shaped partition are arranged circumferentially on the inner peripheral surface of the cylindrical wall of the divided cylindrical casing. A plurality of engaging projections formed on the outer peripheral edge of the disk-shaped partition and engaged with each other so as to be immovable in the circumferential direction and the radial direction and movable in the axial direction. Configured.
(6) The engaging protrusion is formed so as to be integrally connected to a cylindrical wall of the divided cylindrical casing and an outer peripheral end portion of the return blade.
(7) The phase of the circumferential mounting position of at least one pair of impellers is deviated within a range of 0.47 pitch or more and 0.53 pitch or less in the front and rear.

  ADVANTAGE OF THE INVENTION According to this invention, the multistage diffuser pump which can reduce noise can be provided, without reducing pump efficiency.

Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings. The same reference numerals used in the embodiments indicate the same or equivalent.
(First embodiment)
A multi-stage diffuser pump 50 according to a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a longitudinal sectional view of a multistage diffuser pump 50 according to a first embodiment of the present invention, FIG. 2 is an enlarged view of a main part of FIG. 1, and a casing assembly 60 and a disk-shaped partition 9 of the multistage diffuser pump 50 of FIG. FIG. 4 is a diagram showing the effect of reducing the noise level of the multistage diffuser pump 50 of FIG.

  The multistage diffuser pump 50 of the present embodiment includes an outer cylindrical casing 1, a rotating shaft 4, an impeller 5, an inner cylindrical casing 8, a side plate 10, a guide vane 6, a return vane 7, a disc-shaped partition 9, an engagement protrusion 11, and the like. It is configured with.

  The outer cylindrical casing 1 forms the suction flow path 2 and the discharge flow path 3 of the multistage diffuser pump 50. The suction flow path 2 communicates with the suction side of the first stage impeller 5, and the discharge flow path 3 communicates with the discharge side of the final stage impeller 5. The rotating shaft 4 is horizontally disposed in the outer cylindrical casing 1 and is rotatably supported. The multistage diffuser pump 50 of the present embodiment is a horizontal pump.

  The impeller 5 is attached to the rotary shaft 4 in multiple stages in the axial direction. In the illustrated example, the impellers 5 are installed in five stages, but the present invention can be applied with more or less than that. The impeller 5 is configured to suck fluid from the central opening and to flow outward in the radial direction from the outer peripheral end face opening.

  The inner cylindrical casing 8 is disposed between the impeller 5 and the outer casing 1 to form a suction flow path and a discharge flow path to the impeller 5, and corresponds to each stage of the impeller 5. It is divided into multiple stages in the axial direction. The divided inner cylindrical casing 8 has a cylindrical wall 81 and a partition wall 82.

  The guide vane 6 is located between the disk-shaped partition 9 and the side plate 10 and guides the fluid flowing out from the outer periphery of the impeller 5 to the outside. The guide vane 6 extends outside the outer periphery of the impeller 5 and is installed so as to be concentric with the rotary shaft 4 and the impeller 5. The outer diameter of the guide vane 6 is smaller than the inner diameter of the cylindrical wall 81 of the inner cylindrical casing 8.

  The side plate 10 is installed between the partition wall 82 of the inner cylindrical casing 8 and the guide vane 6, and guides the fluid flowing out from the outer periphery of the impeller 5 to the outside.

  The return blade 7 is located between the partition wall 82 of the inner cylindrical casing 8 and the disk-shaped partition 9 and guides the fluid flowing out from the outer periphery of the guide blade 6 to the suction side of the next stage impeller 5. is there. The return blade 7 is located on the back side of the guide blade 6 and the impeller 5 (next impeller side) and extends from the outer peripheral side to the inner peripheral side, and is concentric with the rotating shaft 4, the impeller 5 and the guide blade 6. It is installed to become. The outer diameter of the return blade 7 is smaller than the inner diameter of the cylindrical wall 81 of the inner cylindrical casing 8. In the illustrated example, both the guide blades 6 and the return blades 7 are seven, but the present invention can be applied even if there are more or fewer than seven.

  The inner cylindrical casing 8, the side plate 10, the guide vane 6, the return vane 7, and the engagement protrusion 11 are integrally formed of a casting or the like to constitute a casing assembly 60. The side plate 10 is formed integrally with one side of the partition wall 82 of the inner cylindrical casing 8, and the guide blade 6 is formed integrally with the side plate 10. The return blade 7 is integrally formed on the other side of the partition wall 82 of the inner cylindrical casing 8. In other words, the guide vane 6 and the return vane 7 are integrally formed on both sides of the partition wall 82 of the inner cylindrical casing 8. By adopting the integrated configuration, the accuracy of the centering of the side plate 10, the guide blade 6 and the return blade can be improved while improving the strength of the partition wall 82 of the inner cylindrical casing 8.

  The casing assembly 60 is connected and installed in the axial direction by fitting the inner peripheral surface of the cylindrical wall 81 of the inner cylindrical casing 8 to the outer peripheral surface of the side plate 10. Thereby, the centering accuracy of the inner cylindrical casing 8 can be improved.

  The disc-shaped partition 9 divides the flow path of the guide vane 6 and the flow path of the return vane 7 and is installed so as to be movable in a minute range in the axial direction with respect to the inner cylindrical casing 8. That is, the disk-shaped partition 8 has a small gap in the axial direction independently between each casing assembly 60, specifically, one return blade 7 of the adjacent casing assembly 60 and the other The guide blades 6 are independently provided with a minute gap in the axial direction.

  The outer diameter of the disk-shaped partition 9 is smaller than the inner diameter of the cylindrical wall 81 of the inner cylindrical casing 8, and the outer space outside the guide vane 6 and the outer space outside the return vane 7 are discs. It communicates through a space outside the outer periphery of the partition 9. As a result, the fluid that has flowed out of the impeller 5 flows outward along one surface of the disk-shaped partition 9, passes through the communicating portion, and then flows along the other surface of the disk-shaped partition 9. Flowing inward.

  A plurality of engaging protrusions 11 are formed in the circumferential direction on the inner peripheral surface of the cylindrical wall 81 of the inner cylindrical casing 8, and an inner shape engagement that matches the outer shape of the engaging protrusion 11 is formed on the outer peripheral edge of the disc-shaped partition 9. A plurality of joint grooves 12 are formed. The engagement protrusion 11 and the engagement groove 12 are engaged so as not to move in the circumferential direction and the radial direction and to be movable in the axial direction, and prevent the disk-shaped partition 9 from rotating in the circumferential direction. And means for preventing radial movement.

  The engaging protrusion 11 is formed so as to integrally connect the cylindrical wall 81 of the inner cylindrical casing 8 and the outer peripheral end of the return blade 6. Thereby, the strength of the engaging protrusion 11 and the guide blade 6 can be increased.

  When the multi-stage diffuser pump 50 having such a configuration is operated, the fluid passes through the suction flow path 2 of the outer cylindrical casing 1 and the suction side of the inner cylindrical casing 8 and is sucked into the central opening of the first stage impeller 5 to be impeller. 5 flows out to the guide vane 6 from the outer peripheral end face opening. The fluid that has flowed out flows through the flow path of the guide vane 6 along the surface on one side of the disk-shaped partition 9 and communicates between the cylindrical wall 81 of the inner cylindrical casing 8 and the disk-shaped partition 9. After passing through, the flow of the return blade 7 flows inward along the other surface of the disk-shaped partition 9. After the fluid flowing through the flow path of the return vane 7 is sucked into the impeller 5 from the central opening of the second stage impeller 5, the same operation is performed as shown by the arrows in FIG. Then, it is discharged from the discharge flow path 3 of the outer cylindrical casing 1.

  As described in the section of the prior art, turbulent flow is generated in the fluid that flows out from the outer peripheral end face opening of the impeller 5, and the turbulent flow is sandwiched between the guide blade 6 and the return blade 7. By flowing so as to cover the partition 9, a non-uniform pressure difference is generated in the axial direction at the boundary of the disk-shaped partition 9, and a large fluid pressure in the axial direction is applied to the disk-shaped partition 9 by the non-uniform pressure difference. Vibration force is generated.

  In the present embodiment, since the disk-shaped partition 9 is installed so as to be movable in a minute range in the axial direction with respect to the inner cylindrical casing 8, the axial fluid excitation force for the disk-shaped partition 9 is disk-shaped. It can be absorbed by the movement of the partition 9 in the axial direction. Accordingly, the axial vibration of the inner cylindrical casing 8 is suppressed without directly transmitting the axial fluid exciting force to the inner cylindrical casing 8, and noise can be reduced.

  The vibration analysis of the multistage diffuser pump 50 of this embodiment is performed, and the results of evaluating the noise level reduction effect will be described with reference to FIG. The horizontal axis of FIG. 4 represents the frequency at which the noise level in the multistage diffuser pump 50 is dominant. N is the pump rotation frequency, and Z is the number of pump blades. On the contrary, the noise level slightly increases at the NZ frequency, but the noise level is greatly decreased at other frequency components, and it can be seen that the noise level is greatly decreased in total.

  Further, even if the disk-like partition 9 can be moved independently as in the present embodiment, the guide blade 6 and the inner cylindrical casing 8 are maintained in a fixed relationship, so the outer peripheral end surface of the impeller 5 and the guide The gap with the inner peripheral end face of the blade 6 can be narrowed, and sufficient pump efficiency can be ensured.

  If the disk-shaped partition 9 rotates in the circumferential direction during operation of the multistage diffuser pump 50, the flow path of the guide vane 6 and the return vane 7 may be affected, and the pump performance may be deteriorated. In this embodiment, since the means for preventing the rotation of the disk-shaped partition 9 in the circumferential direction is provided with a simple configuration, the performance of the pump can be ensured while suppressing an increase in cost.

Further, if the disk-shaped partition 9 moves in the radial direction during the operation of the multistage diffuser pump 50, the clearance gap between the disk-shaped partition 9 and the impeller 5 increases to increase leakage loss, and the pump performance. May deteriorate. In this embodiment, since the means for preventing the disc-shaped partition 9 from moving in the radial direction is provided with a simple configuration, the performance of the pump can be ensured while suppressing an increase in cost.
(Second Embodiment)
Next, the multistage diffuser pump 50 according to the second embodiment of the present invention will be described. The second embodiment is different from the first embodiment in the points described below, and the other points are basically the same as those in the first embodiment, and thus redundant description is omitted.

  In this second embodiment, in addition to the first embodiment, in order to further reduce the axial vibration exciting force, the phase of the circumferential mounting position of at least one set of impellers 5 is 0.47 pitch or more in the front and rear directions. It is shifted within a range of 0.53 pitch or less. Thereby, as shown in FIG. 5, the axial fluid exciting force can be further reduced. This reduction method is irrelevant to the capacity and rotation speed of the pump, and can be applied to a multistage diffuser pump.

It is a longitudinal cross-sectional view of the multistage diffuser pump of 1st Embodiment of this invention. It is an enlarged view of the principal part of FIG. It is a disassembled perspective view which shows the relationship between the casing assembly of the multistage diffuser pump of FIG. 1, and a disk-shaped partition. It is a figure showing the reduction effect of the noise level of the multistage diffuser pump of FIG. It is a characteristic view of the fluid exciting force of the axial direction of the multistage diffuser pump of 2nd Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Outer cylindrical casing, 2 ... Suction flow path, 3 ... Discharge flow path, 4 ... Rotating shaft, 5 ... Impeller, 6 ... Guide vane, 7 ... Return vane, 8 ... Inner cylindrical casing, 9 ... Disc shape Partition 10, side plate 11, engagement protrusion 12, engagement groove 50, multi-stage diffuser pump 60, casing assembly 81, cylindrical wall 82, partition wall

Claims (8)

An impeller mounted on the rotary shaft in multiple stages in the axial direction;
A cylindrical casing forming a flow path to the impeller;
Guide vanes for guiding the fluid flowing out from the outer periphery of the impeller to the outside;
A return blade that guides the fluid flowing out from the outer periphery of the guide blade to the inner periphery,
In a multistage diffuser pump comprising a disk-shaped partition that partitions the flow path of the guide blade and the flow path of the return blade,
The disk-shaped partition is installed so as to be movable in a minute range in the axial direction with respect to the cylindrical casing.   2. The cylindrical casing according to claim 1, wherein the cylindrical casing is divided into a plurality of parts corresponding to the respective stages of the impeller, and the divided cylindrical casing, the return blade, and the guide blade are formed as a single-piece casing assembly. The multi-stage diffuser pump is characterized in that the disk-like partition is installed between the casing assemblies independently with a minute gap in the axial direction.   3. The disk according to claim 2, wherein the divided cylindrical casing includes a cylindrical wall and a partition wall, and the return blade and the guide blade are integrally formed on both sides of the partition wall of the divided cylindrical casing, The multi-stage diffuser pump is characterized in that the partition is installed with a small gap in the axial direction independently between the one return blade and the other guide blade of the adjacent casing assembly.   4. The multistage diffuser pump according to claim 2, further comprising means for preventing rotation of the disk-shaped partition in the circumferential direction.   5. The multistage diffuser pump according to claim 4, further comprising means for preventing movement of the disk-shaped partition in the radial direction.   The means for preventing circumferential rotation of the disk-shaped partition and the means for blocking radial movement of the disk-shaped partition according to claim 5 are provided on an inner peripheral surface of a cylindrical wall of the divided cylindrical casing. A plurality of engagement protrusions formed in the circumferential direction and a plurality of engagement grooves formed in the outer peripheral edge of the disc-shaped partition are engaged so as to be immovable in the circumferential direction and the radial direction and movable in the axial direction. A multi-stage diffuser pump characterized by being combined.   7. The multistage diffuser pump according to claim 6, wherein the engaging protrusion is formed so as to be integrally connected to a cylindrical wall of the divided cylindrical casing and an outer peripheral end portion of the return blade.   2. The multistage diffuser pump according to claim 1, wherein a phase of at least one pair of impellers in a circumferential direction is shifted in a range of 0.47 pitch or more and 0.53 pitch or less in the front-rear direction.

Images