JP2006291937A - Impeller for centrifugal pump and centrifugal pump having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent vibration from occurring by discharging all air inside the partitioned chamber of an impeller to avoid the loss of mechanical balance produced by the buoyancy of air. <P>SOLUTION: A circular cover 70 cut out at its center portion is fitted to the ceiling surface of the impeller 11 with bolts 60. The partitioned chamber is formed of the cover 70 and the ceiling surface 30 with a recess. A balance weight is fitted to the rear surface (partitioned chamber side) of the cover 70 with bolts 83. A plurality of holes 81 passed between the inside and the outside of the partitioned chamber are formed at the inner end part of the cover 70 around the rotating axis thereof. As the impeller 11 is rotated, air is discharged through one hole 81 and water is taken in through the other holes 81 to discharge all air inside the partitioned chamber. <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.

The groove portion thus scraped is usually provided with a lid in order to reduce power loss due to fluid disturbance. Therefore, the lid forms a hollow compartment in the groove portion. However, if this compartment is covered with a lid in an airtight manner and external water is blocked, a large pressure is applied to the lid, so the strength of the lid must be set high. For this reason, an impeller has been proposed in which a hole is provided so that a large pressure is not applied to the lid and water is introduced into the compartment to make the internal and external pressure uniform (see, for example, Patent Document 1).
JP-A 49-105046

  However, even if a water introduction hole is provided in the lid and water is introduced into the compartment through the introduction hole, bubbles often remain in the compartment. That is, all the air inside the compartment is not discharged, and a part is left in the compartment.

  However, if air is left inside the compartment, the air exerts buoyancy on the impeller. For this reason, this buoyancy causes the impeller to lose mechanical balance and cause vibration during rotation. In addition, with the rotation of the impeller, the remaining air frequently moves in the compartment, causing a problem of further amplifying the vibration.

  The present invention has been made in view of such a point, and an object of the present invention is to provide an impeller that prevents the residual air from remaining in the compartment and prevents the vibration caused by the residual air, and the impeller. It is to provide a centrifugal pump.

  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, a discharge port formed laterally, and the suction port and the above A partition chamber is formed between the substantially cylindrical impeller body in which an internal flow path connecting the discharge port is partitioned and the other end of the impeller body so as to cover the recess. And a lid that rotates together with the impeller body, and two or more holes that communicate the inside and outside of the compartment are formed at a position that is 1/2 or less of the radius from the center of rotation of the lid. It is.

  According to the impeller, two or more holes are formed on the rotation center side of the lid. When the impeller rotates, water receives centrifugal force and moves outward from the center of rotation inside the compartment formed by the lid and the recess, and conversely, air having a lower density than water moves inward. . Therefore, the air in the compartment moves to the vicinity of the hole. Here, since two or more holes are provided, water is introduced into the compartment from at least one hole, air is pushed out from the other holes, and the air in the compartment is smoothly discharged. become. Therefore, the mechanical balance of the impeller is not lost due to buoyancy, and the occurrence of vibration can be suppressed.

  It is preferable that at least two of the holes are formed at positions shifted from each other in the circumferential direction.

  As a result, the air in the compartment is discharged smoothly.

  It is preferable that at least two of the holes are formed at positions apart from each other by 90 ° or more around the center of rotation.

  As a result, the air in the compartment is discharged smoothly.

  The holes are preferably provided on one end side and the other end side in the circumferential direction of the recess.

  As a result, air is smoothly discharged throughout the compartment.

  The lid may cover substantially the entire other end of the impeller body.

  This simplifies the configuration of the impeller. If substantially the entire other end of the impeller body is covered with a lid, air tends to remain in the compartment, but according to the present impeller, air can be prevented from remaining as described above.

  The impeller may include a balance weight disposed on the concave side of the lid, and at least one of the holes may be formed closer to the center of rotation than the balance weight in the radial direction.

  According to the impeller, since the balance weight is provided, the mechanical balance and the balance during the underwater rotation of the impeller (hereinafter referred to as hydraulic balance) can be easily maintained. Since the balance weight is disposed inside the compartment, it does not protrude outward. Therefore, power loss due to fluid disturbance can be prevented. If a balance weight is provided inside the compartment, bubbles may stay in the vicinity of the balance weight. However, according to the impeller, since at least one of the holes is formed inside the balance weight, the bubbles are smoothly discharged through the hole. Therefore, it is possible to prevent the air from staying in the compartment even though the balance weight is arranged in the compartment.

  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 An outer blade that is formed in a shape such that a part of the outer peripheral portion on the discharge port side is shaved 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 may be formed in a spiral shape.

  In the impeller, the fluid sucked from the suction port flows through the spiral internal flow path, and then flows through the external flow path along the outer peripheral surface of the impeller body. Therefore, the performance of the pump is improved.

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

  As a result, it is possible to prevent the occurrence of vibration and the like due to the air in the impeller, and to obtain a high-performance centrifugal pump.

  As described above, according to the present invention, the air in the compartment of the impeller can be discharged smoothly. Therefore, it is possible to avoid the mechanical balance from being lost due to the buoyancy of the residual air of the impeller, and it is possible to prevent the residual air from frequently moving in the compartment. Therefore, it is possible to prevent the vibration of the impeller due to the residual air.

  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 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 has three protrusions 61 formed with bolt holes at regular 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, 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 compartment 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 provided on the center of rotation of the lid 70 (which is also the axis center of the drive shaft 18). It has been. The hole 81 is particularly preferably formed in the vicinity of the center of rotation of the lid 70, and may be formed, for example, at a position 2/5 or less of the radius or 1/3 or less of the radius from the center of rotation.

  Further, these holes 81 are formed on the inner side in the radial direction than the balance weight 80. These holes 81 are formed at positions shifted from each other in the circumferential direction, and are located on both sides of the balance weight 80 in the circumferential direction. At least two of these holes 81 are formed at positions apart from each other by 90 ° or more around the center of rotation. The holes 81 may be provided on both sides (substantially point symmetrical positions) across the center of rotation.

  In the present embodiment, all the holes 81 are arranged in a circumferential shape, but at least two holes 81 may be arranged in the radial direction. In the present embodiment, five holes 81 are formed from one end in the circumferential direction of the recess 33 of the impeller body 11a to the center. However, as shown in FIG. 19, the holes 81 may be formed on one end side and the other end side in the circumferential direction of the recess 33. Of course, the hole 81 may be provided from one end to the other end of the recess 33 in the circumferential direction. The holes 81 may be formed uniformly from one end of the recess 33 in the circumferential direction to the other end.

  Through these holes 81, the inside and the outside of the compartment 51 communicate with each other (see FIG. 10 and the like), and water and air enter and exit from the holes 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).

  Although the shape of the hole 81 is not limited at all, in the present embodiment, the hole 81 is formed in a circular shape. The plurality of holes 81 may be holes having different shapes or dimensions, or may be holes having the same shape or dimensions.

  As shown in FIGS. 7, 9, 10, and 12, the discharge port 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 extending from the suction port 29 of the suction portion 27 to the discharge port 34 is partitioned and formed inside the impeller 11. Yes. 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. ).

  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.

  When the pump 10 is immersed in water, water flows into the compartment 51 of the impeller 11, and most of the air in the compartment 51 is pushed out by the water that has flowed in. However, some bubbles may remain inside the compartment 51 even after the pump 10 is immersed in water.

  That is, when the pump 10 is immersed in water, the specific gravity of the air inside the compartment 51 is small, so that air gradually escapes through the hole 81 of the lid 70 or from the gap between the impeller body 11a and the lid 70. On the other hand, as the air in the compartment 51 decreases, external water flows into the compartment 51 from the hole 81 or the gap. By such movement of water and air, the air in the compartment 51 is replaced with water. However, all of the air in the compartment 51 is not discharged and a part of the air is left in the compartment 51.

  However, in the present embodiment, as will be described below, the residual air is discharged through the hole 81 as the impeller 11 rotates (in other words, the operation of the submersible pump 10). That is, when the rotation of the impeller 11 is started, water inside the compartment 51 receives centrifugal force and moves outward from the center of rotation, and air having a specific gravity smaller than that of water moves toward the inside of the center of rotation. The air left in the compartment 51 is discharged to the outside through the hole 81 when it reaches the hole 81 provided on the rotation center side of the lid 70. On the other hand, with the discharge of air in the compartment 51, water flows into the compartment 51 from the other hole 81, and smooth replacement of air and water is performed. The air discharged from the compartment 51 of the impeller 11 passes through the gap between the impeller 11 and the pump casing 12 and is discharged out of the pump 11 through the discharge port 24 or the air vent valve 85 (see FIG. 1). It will be.

  As described above, according to the present embodiment, all the air inside the compartment 51 is discharged and the compartment 51 is filled with water. Therefore, according to the impeller 11 which concerns on this embodiment, the mechanical balance of the impeller 11 is not destroyed by the buoyancy of air, and generation | occurrence | production of a vibration can be prevented. Further, air does not frequently move in the compartment 51 with the rotation of the impeller 11, and the occurrence of vibration can be prevented in this respect.

  Moreover, the lid 70 of the impeller 11 according to the present embodiment has two or more holes 81. Thereby, the discharge of air and the introduction of water can be performed through separate holes 81. Therefore, unlike the case where there is only one hole 81, the discharge of air is not hindered by the inflow of water, and air and water can be smoothly replaced.

  Furthermore, in this embodiment, all the holes 81 of the lid 70 are provided at the inner end, and no holes 81 are provided outside the half of the radius from the center of rotation of the lid 70. Therefore, the water that has been subjected to the centrifugal force and moved to the outside of the rotation is not discharged from the compartment 51. Therefore, the water in the compartment 51 tends to gather outside, and conversely, the air in the compartment 51 tends to gather inside. Therefore, air can be concentrated inside the compartment 51, and the air in the compartment 51 can be efficiently discharged through the holes 81 provided inside.

  A balance weight 80 is attached to the lid 70 of 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 unbalance of the fluid force that the impeller 11 receives. Therefore, the hydraulic balance of the impeller 11 can be maintained, and the occurrence of vibration of the impeller 11 can be prevented.

  Moreover, according to the impeller 11 which concerns on this embodiment, the balance weight 80 is arrange | positioned at the back side of the lid | cover 70, ie, the hollow 33 side of the impeller main body 11a. Therefore, there is no protrusion due to the balance weight 80 on the front side of the lid 70, and power loss due to fluid disturbance can be suppressed. In the present embodiment, the hole 81 is provided inside the balance weight 80. The hole 81 is provided in the vicinity of the balance weight 80. Therefore, air does not stay near the balance weight 80 and the air is efficiently discharged.

  According to this embodiment, the single hollow 33 is provided in the end of the axial direction of the impeller main body 11a, and the lid | cover 70 has covered the substantially whole end of the impeller main body 11a. The lid 70 is made of a single member. Therefore, the configuration of the impeller 11 is simplified. If substantially the entire end of the impeller body 11 a is covered with the lid 70, air may easily remain in the compartment 51. However, according to the present embodiment, as described above, the air in the compartment 51 is smoothly discharged. Accordingly, vibrations caused by residual air in the impeller 11 can be prevented, and the configuration of the impeller 11 can be simplified.

  In addition, although the primary flow path 35 of the impeller 11 which concerns on this embodiment was helical, it should just be a spiral shape seeing from a rotating shaft direction, and is not limited to a spiral shape.

  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 the impeller of the state which removed the cover. 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. FIG. 6 is a view corresponding to FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Centrifugal pump 11 Impeller 11a Impeller main body 27 Suction part 28 Discharge part 29 Suction port 33 Depression 34 Discharge port 35 Primary flow path 36 Primary blade 37 Secondary flow path 38 Secondary blade 40 Flange 51 Compartment room 70 Lid 80 Balance weight 81 holes

Claims (8)

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 an internal flow path that connects the suction port and the discharge port is formed inside A substantially cylindrical impeller body,
A partition chamber is formed between the impeller body and the recess by being attached to the other end of the impeller body so as to cover the recess, and includes a lid that rotates together with the impeller body,
An impeller for a centrifugal pump, in which two or more holes communicating with the inside and the outside of the compartment are formed at a position of ½ or less of the radius from the center of rotation of the lid.   The impeller for a centrifugal pump according to claim 1, wherein at least two of the holes are formed at positions shifted from each other in the circumferential direction.   The impeller for a centrifugal pump according to claim 2, wherein at least two of the holes are formed at positions apart from each other by 90 ° or more around the center of rotation.   The impeller for a centrifugal pump according to any one of claims 1 to 3, wherein the hole is provided on one end side and the other end side in the circumferential direction of the recess.   The centrifugal pump impeller according to any one of claims 1 to 4, wherein the lid covers substantially the entire other end of the impeller body. A balance weight disposed on the concave side of the lid;
The impeller for a centrifugal pump according to any one of claims 1 to 5, wherein at least one of the holes is formed closer to a center of rotation than the balance weight in the radial direction. 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;
An outer blade that is formed in a shape in which a part of the outer peripheral portion on the discharge port side than the flange portion 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 And comprising
The centrifugal pump impeller according to any one of claims 1 to 6, wherein the internal flow path is formed in a spiral shape. The centrifugal pump provided with the impeller for centrifugal pumps as described in any one of Claims 1-7.

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