JP2006291938A - Impeller for centrifugal pump and centrifugal pump having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the occurrence of vibration by eliminating the unbalance of a fluid force produced when an impeller is rotated in a fluid by a simple structure. <P>SOLUTION: Three projected parts 61 for supporting bolts are formed, at equal intervals, on the ceiling surface 30 of an impeller body 11a, and a circular cover 70 cut out at its center portion is fitted onto the projected parts 61 with bolts 60. A balance weight 80 is fitted to the rear surface (inner side) of the cover 70 with bolts, and the cover 70 is disposed so that the balance weight 80 can be disposed in a recess 33 formed in a part of the ceiling surface 30. A fluid force applied to the vanes while the impeller is rotated is canceled by a centrifugal force applied to the balance weight 80 to suppress the occurrence of vibration. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a centrifugal pump impeller and a centrifugal pump including the impeller.

  Conventionally, centrifugal pumps are often used in various facilities such as drainage facilities. The centrifugal pump is configured such that an impeller coupled to a motor shaft is accommodated in a spiral casing.

  Various types of centrifugal pump impellers are used depending on the application. For example, in applications such as discharge of sewage in a sewage tank, since solids may be contained in the sewage, an impeller that can discharge solids with less clogging is preferable. A so-called non-clog type impeller is known as such an impeller.

  The non-clog type impeller is composed of a substantially cylindrical body having a suction port formed at one end and a discharge port provided on a side surface. Inside the cylindrical body, a flow path that is formed in a spiral shape when viewed from the axial direction and connects the suction port and the discharge port is formed. This flow path is partitioned by one blade. Therefore, the blades of the non-clog type impeller have a non-axisymmetric shape with respect to the rotation axis. Therefore, if this impeller is left as it is, a static balance at rest and a dynamic balance at the time of air rotation (hereinafter referred to as mechanical balance) cannot be achieved, which causes deterioration in assembly workability and vibration during rotation. It becomes. Therefore, in general, in this type of impeller, mechanical balance is maintained by cutting a portion having a large weight.

  However, in the above impeller, even if the mechanical balance is corrected, the balance of rotation of the impeller (hereinafter referred to as hydraulic balance) may be lost as the pump is operated. That is, when the pump is operated, the impeller rotates, and the impeller blades are subjected to force by the sucked fluid such as sewage. At this time, since the blade has a non-axisymmetric shape, the distribution of force applied to the blade is also non-axisymmetric. Therefore, unlike the impeller having a plurality of blades arranged in an axially symmetrical manner, the impellers do not cancel the fluid forces acting on the blades. Therefore, in the above-described impeller, even if the mechanical balance is corrected, unbalance is caused by the fluid force during the pump operation, which may cause vibration.

  Therefore, in order to eliminate the unbalanced state of hydraulic balance as described above, a method has been proposed in which a balance weight is attached to the impeller and the fluid force is unbalanced by centrifugal force generated in the balance weight (for example, a patent) Reference 1).

In the impeller disclosed in Patent Document 1, a part of the weight is removed by providing a groove on a part of the surface. On the other hand, a protrusion having a groove is provided on the other part of the surface of the impeller, and a balance weight is attached inside the groove.
Japanese Utility Model Publication No. 45-11447

  However, if a projection is provided on the surface of the impeller to attach a balance weight as in the impeller disclosed in Patent Document 1, the fluid on the surface side of the impeller is likely to be disturbed during rotation, resulting in loss of power. It was big. Further, since the balance weight was directly attached to the surface of the impeller, the attachment position of the balance weight could not be changed unless the impeller mold itself was changed. Therefore, fine adjustment of the balance weight has been difficult after casting the impeller.

  The present invention has been made in view of the above points, and an object of the present invention is to eliminate the unbalance of the fluid force generated in the impeller during rotation with a simple configuration and effectively prevent the occurrence of vibration. It is an object of the present invention to provide an impeller capable of performing the above and a centrifugal pump including the impeller.

  The centrifugal pump impeller according to the present invention has a suction port formed at one end and a recess recessed in the axial direction at the other end, and a discharge port formed at the side. A substantially cylindrical impeller body having blades defining an internal flow path connecting the suction port and the discharge port, a lid covering at least the recess of the impeller body, and the lid Balance weight.

  In the impeller, a concave portion is formed in the impeller body, and the mechanical balance of the impeller body is maintained by the concave portion. Moreover, the impeller according to the present invention includes a lid provided with a balance weight. Since the recess of the impeller body is covered with the lid, the fluid disturbance in the recess is suppressed. Therefore, it is possible to suppress the occurrence of vibration due to fluid disturbance. Further, when the impeller rotates, a centrifugal force acts on the balance weight, and this centrifugal force cancels the unbalance of the fluid force acting on the blade. Therefore, the hydraulic balance can be maintained, and the vibration and shaft runout of the impeller can be prevented. According to the present invention, the above-described vibration damping effect can be obtained by a simple configuration in which the lid with the balance weight attached is attached to the impeller body. Further, by finely adjusting the balance weight and the lid, the hydraulic balance can be finely adjusted without changing the mold of the impeller body.

  The impeller body protrudes outward along the outer peripheral surface from the suction port side portion with respect to the discharge port on the outer peripheral surface, and separates the suction port side from the discharge port side, and the flange portion A secondary blade that is formed in a shape such that a part of the outer peripheral portion on the discharge port side is scraped inward, and that defines an external flow path that is continuous with the internal flow path and circulates along the outer peripheral surface; The internal flow path is preferably formed in a spiral shape.

  In the impeller, the fluid sucked from the suction port flows in the spiral internal flow path, and then flows in the external flow path along the outer peripheral surface of the impeller body. Therefore, the performance of the pump is improved. Although the blades that define the internal flow path and the entire secondary blade have a non-axisymmetric shape, the mechanical balance and hydraulic balance of the impeller are maintained as described above.

  The balance weight is preferably disposed in the recess.

  In the impeller according to the present invention, a balance weight is disposed in the recess. As a result, it is possible to save space without requiring a new space for the balance weight in order to exert the vibration damping effect as described above. Further, since the balance weight is accommodated in the recess, it is possible to prevent power from being lost due to extra force from the fluid outside the impeller.

  The balance weight is preferably formed integrally with the lid.

  This eliminates the need for attaching the balance weight to the lid and facilitates the assembly of the impeller provided with the balance weight. Moreover, it is possible to prevent the balance weight from falling off the lid due to the rotation of the impeller.

  It is preferable that the balance weight is detachably attached to the lid by a fastener.

  Thus, the balance weight can be easily attached, and the impeller with the balance weight can be easily assembled.

  The lid is preferably detachably attached to the impeller body by a fastener.

  Thus, the lid can be easily attached to the impeller body, and the impeller can be easily assembled.

  The centrifugal pump according to the present invention includes the centrifugal pump impeller.

  Thereby, generation | occurrence | production of a vibration etc. is prevented and the centrifugal pump provided with the highly durable impeller is obtained.

  As described above, according to the present invention, an impeller having a mechanical balance and a hydraulic balance can be obtained with a simple configuration. That is, according to the present invention, based on a simple configuration, it is possible to suppress fluid turbulence caused by the concave portion of the impeller, and to prevent the unbalance of fluid force generated in the blades when the impeller is rotated. This can be eliminated, and the occurrence of vibration and shaft runout can be suppressed.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 1, the centrifugal pump according to the embodiment is a turbo centrifugal pump 10 for sewage treatment. The pump 10 includes an impeller 11, a pump casing 12 that covers the impeller 11, and a sealed submersible motor 13 that rotates the impeller 11.

  The underwater motor 13 includes a motor 16 including a stator 14 and a rotor 15, and a motor casing 17 that covers the motor 16. A drive shaft 18 extending in the vertical direction is provided at the central portion of the rotor 15. The drive shaft 18 is rotatably supported by bearings 19 and 20. The lower end portion of the drive shaft 18 is connected to the impeller 11, and the rotational driving force of the submersible motor 13 is transmitted to the impeller 11.

  The pump casing 12 covers the impeller 11 and forms a flow path 50 for discharging sewage discharged from the impeller 11 to the outside of the pump. Inside the pump casing 12, a pump chamber 26 is formed that is surrounded on the outer peripheral side by a side wall 12 a that is curved in a semicircular shape in a sectional view. In the pump chamber 26, a discharge portion 28 (see FIG. 3) of the impeller 11 is accommodated. As shown in FIG. 1, a part of the pump chamber 26 constitutes the flow path 50 in a state where the impeller 11 is disposed in the pump casing 12.

  As shown in FIG. 1, a suction portion 21 that protrudes downward is formed in the lower portion of the pump casing 12. The suction portion 21 is formed with a suction port 22 that opens downward. The suction port 22 communicates with the suction port 29 of the impeller 11. On the other hand, a discharge portion 23 protruding to the side is formed on the side of the pump casing 12. The discharge portion 23 is formed with a discharge port 24 that opens to the side. The discharge port 24 is an outlet of the flow path 50, and the sewage discharged from the impeller 11 is discharged from the discharge port 24 to the outside of the pump.

  As shown in FIG. 2, the impeller body 11a of the impeller 11 is provided with a suction portion 27 and a discharge portion 28 in order from the lower side in the axial direction toward the upper side. The suction part 27 and the discharge part 28 are both formed in a substantially cylindrical shape, and the discharge part 28 is configured to have a larger diameter than the suction part 27. And between the discharge part 28 and the suction part 27, the flange part 40 is formed over the perimeter. As shown in FIG. 1, the flange portion 40 partitions the discharge portion 28 and the suction portion 27 of the impeller 11 vertically. That is, the impeller 11 is a closed type impeller in which the suction portion 27 and the discharge portion 28 are partitioned by the flange portion 40.

  As shown in FIG. 2, a suction port 29 that opens downward is provided at the lower end of the suction portion 27. On the other hand, a ceiling surface 30 (see FIG. 4) is formed at the upper end of the discharge portion 28.

  As shown in FIG. 4, the ceiling surface 30 is provided with three protrusions 61 formed with bolt holes at equal intervals. On a part of the ceiling surface 30 (here, the three-quarters of the ceiling surface 30 when viewed from the axial direction and on the side where the weight of the impeller 11 is large), a depression 33 that is recessed downward is formed. Yes. By this recess 33, the impeller 1 is reduced in weight, mechanically balanced, and rotational stability is improved. However, the size and shape of the recess 33 in the ceiling surface 30 are not limited at all. Further, as long as the mechanical balance is maintained, the recess 33 is not necessarily required, and the shape of the ceiling surface 30 is not particularly limited.

  As shown in FIG. 3, on the ceiling surface 30 of the impeller body 11 a, a circular lid 70 with a center portion cut out is attached by a bolt 60. An attachment portion 31 for attaching the drive shaft 18 is formed at the center of the impeller body 11a, and the attachment portion 31 is inserted into a notch portion at the center of the lid 70. An insertion hole 32 for inserting the tip of the drive shaft 18 is formed in the center of the mounting portion 31. The lid 70 covers the recess 33 of the impeller body 11a, and a chamber 51 is formed by the lid 70 and the ceiling surface 30 (see FIGS. 9 to 16).

  As shown in FIGS. 12 and 16, a balance weight 80 is attached to the back surface (inner side) of the lid 70 with bolts 83. The balance weight 80 cancels out the unbalance of the fluid force generated when the impeller 11 rotates, and suppresses the occurrence of vibration. In the present embodiment, the balance weight 80 is located at a place where the depression 33 is most depressed, but the position of the balance weight 80 is not limited at all. Further, the number, size, and shape of the balance weight 80 are not limited at all.

  As shown in FIG. 3, a plurality of holes 81 are formed in the inner end portion of the lid 70. These holes 81 are formed on the inner side of the balance weight 80 in the radial direction. These holes 81 are located on both sides of the balance weight 80 in the circumferential direction. Through the hole 81, the inside and the outside of the chamber 51 communicate with each other (see FIG. 10 and the like), and water and air enter and exit from the hole 81. The air discharged from these holes 81 passes through the gap between the impeller 11 and the pump casing 12 and is discharged out of the pump 10 through the discharge port 24 or the air vent valve 85 (see FIG. 1).

  On the other hand, as shown in FIGS. 7, 9, 10, and 12, the discharge portion 28 of the impeller 11 is formed with a discharge port 34 that opens to the side. As shown in FIGS. 6, 7, and 9 to 18, a spiral primary flow path 35 (spiral flow path) extending from the suction port 29 of the suction portion 27 to the discharge port 34 is disposed inside the impeller 11. ) Are formed. That is, as shown in FIG. 17, the discharge port 34 opens toward the extending direction of the spiral primary flow path 35. In the present specification, a partition wall that partitions the primary flow path 35 is referred to as a primary blade 36.

  As shown in FIGS. 2 and 5 to 18, a secondary flow path 37 that is recessed inward so as to extend along the outer peripheral surface is formed in a part on the outer peripheral surface of the discharge unit 28. As shown in FIG. 17, the secondary flow path 37 is continuous with the downstream side of the primary flow path 35 formed in the impeller 11 at the discharge port 34. And the secondary flow path 37 circulates the discharge part 28 over the length more than the semicircle of the impeller 11. The downstream end of the secondary flow path 37 extends to the vicinity of the discharge port 34. The length of the secondary flow path 37 is preferably not less than one half and less than one turn, but is not particularly limited.

  That is, the secondary flow path 37 is a non-spiral flow path, and the flow path center is located on an orthogonal plane orthogonal to the axis of the impeller 11. When the partition wall that partitions the secondary flow path 37 is referred to as a secondary blade 38, the secondary blade 38 is a so-called radial flow blade, and sewage is discharged to the outer peripheral side (radially outer side) by the secondary blade 38. ).

  The above is the configuration of the pump 10 according to the present embodiment. Next, a method for manufacturing the impeller 11 will be described.

  First, the impeller body 11a is cast using a metal material such as stainless steel. At this time, in order to reduce the weight and ensure the mechanical balance, the impeller body 11a is provided with a depression 33 in advance. That is, by providing the recess 33, a portion that is not particularly necessary in terms of strength is eliminated, and further, the mechanical balance of the impeller body 11a having a non-axisymmetric shape is achieved.

  On the other hand, a lid 70 is manufactured separately from the impeller body 11a. The balance weight 80 is attached to the lid 70 with bolts 83. Next, the bolt hole of the lid 70 and the bolt hole of the protrusion 61 of the impeller body 11a are aligned, and the lid 70 is bolted to the impeller body 11a. That is, the lid 70 is placed on the ceiling surface 30 of the impeller 11 and fixed with the bolts 60. As a result, the balance weight 80 is disposed at a predetermined position in the recess 33 (a position where the fluid force generated during the rotation of the impeller 11 is canceled).

  In this pump 10, sewage is conveyed as follows. That is, the impeller 11 is rotated by the submersible motor 13, and the primary blade 36 of the impeller 11 sucks sewage upward from the lower suction port 29 by this rotation. The sucked sewage passes through the spiral primary flow path 35 in the impeller 11 and is discharged to the outer peripheral side by the discharge port 34 and the secondary blade 38. The discharged sewage is received by the pump casing 12 that covers the impeller 11, flows through the flow path 50, and then is discharged from the discharge port 24 to the outside of the pump.

  As described above, according to the impeller 11 according to this embodiment, the recess 33 is provided in the ceiling surface 30 of the impeller body 11a. Thereby, the weight reduction of the impeller 11 can be achieved and a mechanical balance can be taken together.

  Further, according to the present embodiment, the recess 33 of the impeller body 11 a is covered with the lid 70. Therefore, the fluid flow is prevented from being disturbed by the recess 33, and the efficiency of the pump can be improved. In addition, vibration caused by flow disturbance can be suppressed.

  In the impeller 11 of the present embodiment, the primary blade 36 and the secondary blade 38 are continuous, and form a single blade that is spiral when viewed from the axial direction. In such a single blade impeller 11, the blades have a non-axisymmetric shape. For this reason, the force of the fluid (sewage) applied to the blades is different on one side and the other side of the blades, and is an unbalanced force as a whole. Therefore, the fluid force does not cancel out like an impeller having axisymmetrically shaped blades, and vibrates the impeller. However, a lid 70 to which a balance weight 80 is fixed is attached to the impeller 11 according to the present embodiment. Therefore, when the impeller 11 rotates, a centrifugal force acts on the balance weight 80, and this centrifugal force acts so as to cancel the fluid force. Therefore, according to the impeller 11 which concerns on this embodiment, not only mechanical balance but hydraulic balance can be taken, and generation | occurrence | production of a vibration can be prevented effectively.

  In the impeller 11 according to the present embodiment, the balance weight 80 is attached to the lid 70 and the lid 70 is attached to the impeller 11 main body, instead of attaching the balance weight to the impeller main body 11a. Therefore, the balance weight 80 can be appropriately installed regardless of the shape of the impeller body 11a (for example, without being influenced by the unevenness of the ceiling surface 30). Therefore, the balance weight 80 can be easily installed at a position suitable for preventing vibration.

  Further, when it is necessary to finely adjust the mounting position of the balance weight 80, etc., it is sufficient to improve a part of the lid 70, and it is not necessary to improve the impeller body 11a. Therefore, there is no need to change the mold of the impeller body 11a, and fine adjustment of the balance can be easily performed.

  Further, in the impeller 11 according to the present embodiment, the balance weight 80 is provided in the above-described recess 33. Therefore, it is not necessary to secure a new space for installing the balance weight 80 as in the prior art. Therefore, vibration of the impeller 11 by the balance weight 80 can be realized while saving space and weight.

  The balance weight 80 of the impeller 11 according to the present embodiment is detachably attached to the lid 70 by a bolt 83. The lid 70 is detachably attached to the impeller 11 with a bolt 60. This eliminates the need for time-consuming work such as welding as in the prior art, and facilitates the attachment work. In addition, it is possible to reduce the running cost from the reduction of the manufacturing cost and the ease of maintenance.

  Although the primary flow path of the impeller 11 according to the present embodiment has a spiral shape, it may be spiral when viewed from the rotation axis direction, and is not limited to a spiral shape.

  In the impeller 11 according to the present embodiment, the balance weight 80 is attached to the lid 70 with the bolt 83, but the fastener for detachably attaching the balance weight 80 is not limited to the bolt 83. Things (for example, screws) may be used. Moreover, the fastener which attaches the lid | cover 70 to the impeller main body 11a so that attachment or detachment is possible is not restricted to the volt | bolt 60, Another thing may be used.

  In the above embodiment, the balance weight 80 and the lid 70 are coupled by the bolt 60, but the balance weight 80 may be formed integrally with the lid 70. As a result, the work of attaching the balance weight 80 to the lid 70 becomes unnecessary, and the impeller 11 can be easily assembled. Further, it is possible to prevent the balance weight 80 from dropping from the lid 70 due to the rotation of the impeller 11. The balance weight 80 and the lid 70 may be formed of the same or different materials and integrated by joining them. Even in this case, the balance weight 80 can be prevented from falling off from the lid 70.

  As described above, the present invention is useful for an impeller for a centrifugal pump and a centrifugal pump including the impeller.

It is sectional drawing of a centrifugal pump. It is the perspective view which looked at the impeller from the downward direction. It is the perspective view which looked at the impeller from the upper part. It is a top view of an impeller body. It is an A direction arrow directional view of FIG. It is a B direction arrow directional view of FIG. It is a C direction arrow directional view of FIG. It is a D direction arrow directional view of FIG. It is the NN sectional view taken on the line of FIG. It is MM sectional view taken on the line of FIG. FIG. 5 is a sectional view taken along line LL in FIG. 4. It is the KK sectional view taken on the line of FIG. It is JJ sectional view taken on the line of FIG. It is the II sectional view taken on the line of FIG. It is the HH sectional view taken on the line of FIG. It is the GG sectional view taken on the line of FIG. It is the EE sectional view taken on the line of FIG. FIG. 6 is a sectional view taken along line FF in FIG. 5.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Centrifugal pump 11 Impeller 11a Impeller body 27 Suction part 28 Discharge part 29 Suction port 33 Dimple (recessed part)
34 Discharge port 35 Primary flow path (internal flow path)
36 Primary blade 37 Secondary flow path (external flow path)
38 Secondary blade 40 Flange (flange)
51 rooms 60 bolts (fasteners)
70 Lid 80 Balance weight 83 Bolt (fastener)

Claims (7)

A suction port is formed at one end and a recess recessed in the axial direction is formed at the other end, a discharge port is formed at the side, and is formed in a spiral shape when viewed from the axial direction. The suction port and the discharge port A substantially cylindrical impeller body having blades that divide the internal flow path connecting
A lid covering at least the recess of the impeller body;
A balance weight provided on the lid;
An impeller for a centrifugal pump. The impeller body is
A flange portion that protrudes outward along the outer peripheral surface from the suction port side portion than the discharge port on the outer peripheral surface, and partitions the suction port side and the discharge port side;
A secondary part that is formed in a shape in which a part of the outer peripheral part on the discharge port side than the flange part is cut inward, and that defines an external flow path that is continuous with the internal flow path and circulates along the outer peripheral surface. A feather, and
The impeller for a centrifugal pump according to claim 1, wherein the internal flow path is formed in a spiral shape.   The centrifugal pump impeller according to claim 1 or 2, wherein the balance weight is disposed in the recess.   The impeller for centrifugal pumps according to any one of claims 1 to 3, wherein the balance weight is formed integrally with the lid.   The impeller for a centrifugal pump according to any one of claims 1 to 3, wherein the balance weight is detachably attached to the lid by a fastener.   The centrifugal pump impeller according to any one of claims 1 to 5, wherein the lid is detachably attached to the impeller body by a fastener.   The centrifugal pump provided with the impeller for centrifugal pumps of Claims 1-6.

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