WO2017056441A1

WO2017056441A1 - Centrifugal pump

Info

Publication number: WO2017056441A1
Application number: PCT/JP2016/004221
Authority: WO
Inventors: 寛正清水; 孝尚橘木; 晃政沖添
Original assignee: 新明和工業株式会社
Priority date: 2015-09-30
Filing date: 2016-09-15
Publication date: 2017-04-06
Also published as: JP6434641B2; JPWO2017056441A1

Abstract

A casing (11), which has a housing chamber (110) for a centrifugal impeller (2), also has a bottom surface (117) in which a communication port (111) leading into the housing chamber (110) is formed. Fixed to the bottom surface (117) is a wearing plate (3) that faces an upright end surface of a blade (22) across a gap. The wearing plate (3) is provided with a connecting port (33) that connects to the communication port (111) and integrates with the communication port (111) to constitute an intake port (4) leading into the housing chamber (110), and through-holes (341), (342) forming concave grooves (61), (62) that are recessed away from the wearing plate (3) when the wearing plate (3) is fixed to the bottom surface (117).

Description

Centrifugal pump

The technology disclosed herein particularly relates to a centrifugal pump provided with a semi-open centrifugal impeller.

As a centrifugal pump impeller suitable for conveying sewage or the like, a semi-open centrifugal impeller configured by standing a blade with respect to a rear shroud is known. For example, Patent Document 1 discloses a configuration in which a centrifugal pump including such a semi-open centrifugal impeller includes a casing having a storage chamber for the centrifugal impeller. The casing according to Patent Document 1 is configured such that a bottom lid in which a suction port is formed is separate and detachable from the casing body, and a part of the storage chamber is partitioned by the upper surface of the bottom lid. A concave groove is recessed on the upper surface of the bottom lid according to Patent Document 1, and foreign matter that has entered the concave groove is crushed by a blade that moves relative to the upper surface of the bottom lid. As a result, foreign matter may be caught between the standing end of the blade (that is, the lower end surface) and the upper surface of the bottom cover, causing the centrifugal pump to be overloaded and hindering the start of the intermittently driven centrifugal pump. This prevents the occurrence of the problem.

International Publication No. 2014/073140

However, in the configuration of Patent Document 1, when the upper surface of the bottom lid is worn due to contact with the blade and the concave groove becomes shallow, or when the concave groove is worn by foreign matter that has entered, the bottom lid needs to be replaced. Therefore, there is a disadvantage that the running cost increases.

The technology disclosed herein has been made in view of such a point, and an object thereof is to reduce running costs in a centrifugal pump including a semi-open centrifugal impeller.

The technology disclosed herein includes a semi-open centrifugal impeller having a disk-shaped shroud and blades erected in the direction of the rotation center axis with respect to the shroud, and a housing for housing the centrifugal impeller. The present invention relates to a centrifugal pump including a casing having a chamber.

In this centrifugal pump, the casing has a bottom surface in which a communication port communicating with the storage chamber is formed, and the bottom surface is disposed between the bottom surface and the standing end surface of the blade, and A wear plate having a predetermined relative clearance with respect to the standing end surface in the direction of the rotation center axis is fixed, and the wear plate is continuous with the communication port and integrated with the communication port. A continuous port constituting a suction port to the storage chamber and a recess that penetrates the wear plate in the thickness direction and is recessed from the relative surface of the wear plate when the wear plate is fixed to the bottom surface. And at least one through hole is provided.

Here, “the standing end surface of the blade” means an end surface on the side away from the shroud in the blade standing on the shroud.

According to this configuration, in a centrifugal pump equipped with a semi-open centrifugal impeller, a wear plate facing the standing end surface of the blade is fixed to the bottom surface of the casing. When the wear plate is fixed, the continuous opening of the wear plate constitutes a suction port into the storage chamber, while the through hole of the wear plate forms a recess. Therefore, the centrifugal pump can crush foreign matter that has entered the storage chamber by the recess formed by the through hole while flowing water from the suction port into the storage chamber. Specifically, the foreign matter that has reached the vicinity of the gap between the standing end face of the blade and the relative surface of the wear plate is carried into the recess as the centrifugal impeller rotates, and moves relative to the wear plate. When the blade to be passed passes over the recess, the blade is sandwiched between the blade and the recess and crushed. In this way, the reduced foreign matter is discharged out of the casing together with water.

The wear plate is a member interposed between the bottom surface of the casing and the standing end surface of the centrifugal impeller. The casing itself is constituted by another member. The wear plate can be constituted by a thin plate, for example.

And if the relative surface of the wear plate wears due to contact with the blade or the through hole wears due to foreign matter entering the recess, only the wear plate needs to be replaced, reducing the replacement cost Is done. As a result, the running cost of the centrifugal pump is suppressed.

Furthermore, according to the above configuration, the wear resistance of the concave portion can be easily adjusted by changing the material of the wear plate according to the operating environment and application of the centrifugal pump, the material of the centrifugal impeller, and the like. it can. For example, by forming the wear plate from a material having higher hardness such as stainless steel, wear of the concave portion can be reduced without changing the material of the casing. Conversely, if the wear plate is made softer than the centrifugal impeller, it is possible to suppress wear of the centrifugal impeller.

Furthermore, according to the above-described configuration, it is possible to selectively use wear plates having different numbers and shapes of through holes according to the operating environment of the centrifugal pump. As a result, foreign matter can be prevented from being caught and the centrifugal pump can be operated stably.

Furthermore, according to the above configuration, since it is possible to form a recess by performing a process of providing a through hole in a plate-like wear plate, a recess is formed in the bottom surface of the casing as described in Patent Document 1. The processability of the centrifugal pump is improved as compared with the process of providing.

Further, at least one of the through holes may extend linearly.

According to this configuration, the recess formed by the through hole extends in a groove shape. If it does so, it will become easy to carry the foreign material which reached the wear board vicinity by the part which the recessed part extended. Moreover, the foreign material which became small by crushing may move in the recessed part extended in groove shape by the pressure difference in a casing. In this case, the crushed foreign matter is transported along the relative surface of the wear plate by moving in a recess extending in a groove shape. In this way, a recess suitable for crushing foreign matter that has entered the storage chamber or transporting the crushed foreign matter is formed.

Further, at least one of the through holes may extend outward in the radial direction from the vicinity of the continuous port.

According to this configuration, the groove-like recess formed by the through-hole extends from the inside in the radial direction to the outside, so that the recess is arranged over a wide radial range. As a result, the foreign matter is easily carried into the recess and crushed.

The relatively small foreign matter that has flowed into the casing may be carried inward in the radial direction due to a pressure difference in the casing.

The concave portion extending from the inside in the radial direction to the outside is effective for smoothly conveying the foreign matter in the concave portion from the outside in the radial direction to the inside.

Further, at least one of the through holes may extend in a direction in which the centrifugal impeller rotates as the distance from the continuous port increases.

As a result of repeated studies by the inventors of the present invention on recesses of various shapes, it was found that such a configuration is effective in crushing foreign matters carried to the recesses.

Further, at least one of the through holes may extend in a direction against the rotation of the centrifugal impeller as the distance from the continuous port increases.

Similarly, according to the knowledge of the inventors of the present application, it has been found that such a configuration is effective in stably operating the centrifugal pump because it can suppress biting of foreign matter.

The through hole may extend in a spiral shape.

Also, the number of the through holes may be one.

Further, the through hole may be connected to the continuous port. The through hole may not be connected to the continuous port.

As described above, according to the centrifugal pump described above, the wear plate provided with the through hole is fixed to the bottom surface of the casing, so that the recess formed by the through hole realizes the crushing of the foreign matter, and the relative wear plate When the surface or the through-hole is worn, the running cost is reduced because only the wear plate needs to be replaced instead of replacing the casing.

It is a longitudinal cross-sectional view of a centrifugal pump. It is a longitudinal cross-sectional view which expands and shows the structure of a casing periphery. It is the perspective view which looked at the centrifugal impeller from the rear surface shroud side. It is the perspective view which looked at the centrifugal impeller from the blade side. It is a disassembled perspective view which shows the structure around a wear plate in detail. It is a top view of a wear plate. It is explanatory drawing which shows the various modifications of a wear plate.

Hereinafter, the centrifugal pump will be described with reference to the drawings. The description of the following embodiment is an example. FIG. 1 shows a centrifugal pump 1 provided with a centrifugal impeller 2 (hereinafter also simply referred to as an impeller 2). FIG. 2 shows an enlarged view of the vicinity of the casing 11 of the centrifugal pump 1. This centrifugal pump 1 is a submersible pump for wastewater treatment. Foreign matter is contained in the water. The centrifugal pump 1 includes an impeller 2, a casing 11 that covers the impeller 2, and a sealed submersible motor 12 that rotates the impeller 2.

The underwater motor 12 includes a motor 15 including a stator 13 and a rotor 14, and a motor casing 16 that covers the motor 15. A drive shaft 17 of the motor 15 is fixed to the center of the rotor 14. The upper bearing 18 and the lower bearing 19 rotatably support the drive shaft 17 extending in the vertical direction along the rotation center axis X. An impeller 2 is attached to the lower end portion of the drive shaft 17. The drive shaft 17 transmits the rotational driving force of the motor 15 to the impeller 2.

The casing 11 has a storage chamber 110 for storing the impeller 2 therein. The casing 11 has a substantially bottomed cylindrical main body 114 disposed with the opening facing upward, and an upper lid 115 that closes the opening of the main body 114. The housing chamber 110 has an inner periphery of the main body 114. The upper surface (hereinafter also referred to as a bottom surface) 117 of the bottom portion 116 of the main body 114 and the lower surface of the upper lid 115 are partitioned. In the example of the casing 11, a bottom portion 116 that is conventionally separated as a bottom lid is also integrally formed. In addition, a casing is good also as a structure which attaches and fixes to a casing main body by making a bottom cover into a different body like the past.

A communication port 111 communicating with the storage chamber 110 is formed in the bottom portion 116 so as to penetrate in the thickness direction so as to be on the rotation center axis X. The communication port 111 is formed in a circular shape in a cross-sectional view (see also FIG. 5), and constitutes the suction port 4 into the storage chamber 110. On the other hand, the discharge part 112 is formed integrally with the main body 114 so as to protrude laterally from the side part of the casing 11. The discharge unit 112 communicates with the storage chamber 110 and has a discharge port 113 that opens to the side.

The impeller 2 is a semi-open type impeller as shown in FIGS. In other words, the impeller 2 includes a rear shroud 21 formed in a substantially disk shape, and a single blade (hereinafter referred to as a blade) 22 erected in the rotation center axis X direction with respect to the rear shroud 21. ing. The shroud 21 has a hub 23 at its center position. The lower end portion of the drive shaft 17 is inserted into the hub 23 and fixed. The impeller 2 is rotationally driven by the motor 15, thereby sucking water through the suction port 4 and discharging water through the discharge port 113 of the discharge unit 112.

The blade 22 is erected on the rear shroud 21 so as to be perpendicular to the shroud surface 210 of the rear shroud 21. As shown in FIG. 4, the blade 22 is disposed so as to have a spiral shape from the radially inner side to the outer side of the impeller 2, and the rear edge thereof is the impeller 2 (in other words, the rear surface It is located near the outer periphery of the shroud 21). The winding angle of the blade 22 is set to be less than 360 °, whereby the blade outlet 24 in which the blade 22 is not formed in the circumferential region of the impeller 2 is set to a relatively large width. Further, the height of the blade 22 is also set to be relatively high, like the width of the blade outlet 24, whereby the impeller 2 ensures a relatively large passing particle diameter. The shape of the blade 22 shown in the figure is an example, and the shape is not limited to this shape.

The blade 22 is made of cast iron (particularly FC250). The material of the blade 22 can be changed as appropriate. For example, it may be made of stainless steel.

Thus, in the centrifugal pump 1, the wear plate 3 is fixed to the bottom surface 117 of the main body 114 as shown in FIG. The wear plate 3 has a continuous port 33 that is continuous with the communication port 111 of the bottom portion 116 and forms the suction port 4 into the housing chamber 110 integrally with the communication port 111, and a plurality of through

holes

341 and 342. is doing. As shown in FIG. 5, the plurality of through

holes

341 and 342 form

concave grooves

61 and 62 that are recessed from the upper surface 31 of the wear plate 3 when the wear plate 3 is fixed to the bottom surface 117. This prevents foreign matter sucked from the suction port 4 from being caught between the standing end (that is, the lower end surface) of the blade 22 and the bottom surface 117. The upper surface 31 of the wear plate 3 is an example of a “relative surface”, and the

concave grooves

61 and 62 are examples of a “concave portion”.

The wear plate 3 is formed in a circular thin plate shape having a smaller diameter than the inner peripheral surface of the main body 114, as shown in FIGS. Six stud bolts 5 are erected on the lower surface of the wear plate 3 at an angular interval of about 60 ° so as to surround the center portion thereof. On the other hand, six bolt holes 118 penetrating in the plate thickness direction are provided in the bottom portion 116 of the main body 114 at positions corresponding to the stud bolts 5. As shown in FIGS. 1 and 2, the wear plate 3 is placed on the bottom surface 117 with each stud bolt 5 inserted through the bolt hole 118. The wear plate 3 is fixed to the bottom surface 117 by fastening the stud bolt 5 inserted through the bolt hole 118 with a nut. When the wear plate 3 is attached to the casing 11, the wear plate 3 is inserted into the casing 11 from the upper end opening of the casing 11, each stud bolt 5 is inserted into the bolt hole 118, and each stud bolt protruding from the lower surface of the casing 11. 5, a nut is fastened from the lower surface side of the casing 11. With this configuration, the wear plate 3 can be fixed to the casing 11 without providing a member protruding from the upper surface 31 of the wear plate 3. Instead of the stud bolt 5, it may be fixed with a flat head screw. That is, although not illustrated, the wear plate 3 is formed with a countersunk through-hole through which a countersunk screw is inserted, while the countersunk screw is screwed into the bottom 116 of the casing 11. Make a screw hole. By doing so, the wear plate 3 is put into the casing 11 from the upper end opening of the casing 11, and the flat plate screw inserted through the wear plate 3 from above is fastened to the screw hole of the casing 11, so that the wear plate 3 is It becomes possible to fix to the casing 11.

The wear plate 3 is disposed between the bottom surface 117 and the standing end surface of the blade 22 as shown in FIGS. The upper surface 31 of the wear plate 3 is opposed to the lower end surface of the blade 22 in the casing 11 with a predetermined gap in the direction of the rotation center axis X, and the centrifugal pump 1 is driven to rotate the impeller 2. As a result, the blade 22 relatively moves on the upper surface 31 of the wear plate 3 along the surface.

The wear plate 3 is made of stainless steel in consideration of wear resistance and corrosion resistance. About the material of the wear plate 3, it is possible to change suitably according to the operating environment and use of the centrifugal pump 1, the material of the impeller 2, etc. It is possible to make the wear plate 3 harder than the impeller 2, and conversely, the wear plate 3 can be made softer than the impeller 2. For example, the wear plate 3 can be made of titanium or the like. The wear plate 3 is not limited to being made of metal, and the wear plate 3 may be made of a synthetic resin such as an acrylic resin. Various coatings may be applied to the surface of the wear plate 3.

As shown in FIGS. 1 to 2 and 5 to 6, the continuous port 33 is formed through the wear plate 3 in the thickness direction, and has a circular shape with the same diameter as the communication port 111. ing. When the wear plate 3 is fixed to the bottom surface 117, the continuous port 33 overlaps with the communication port 111 in the direction of the rotation center axis X, and is integrated with the communication port 111 so as to suck into the storage chamber 110. 4 is configured.

As shown in FIGS. 5 to 6, each through hole is formed to penetrate in the thickness direction of the wear plate 3 and extends linearly outward from the vicinity of the continuous port 33 in the radial direction. More specifically, as shown in FIG. 6, the through

holes

341 and 342 extend in an arc shape along the direction in which the impeller 2 rotates (clockwise in FIG. 6) as the distance from the continuous port 33 increases. There are two through holes 341 and three through holes 342 extending linearly along the direction (counterclockwise in FIG. 6) against the rotation of the impeller 2 as the distance from the continuous port 33 increases. . Note that the number and form of the through holes can be set as appropriate.

Among these, as shown in FIG. 6, the three through holes 341 extending in an arc shape are arranged around the rotation center axis X with an angular interval of about 120 °, while the three through holes 341 extending linearly are arranged. The through holes 342 are arranged between the through holes 341 extending in an arc shape, and are arranged with an angular interval of about 120 ° from each other. Further, the through

holes

341 and 342 are respectively disposed between the stud bolts 5 provided on the lower surface of the wear plate 3.

Further, as shown in FIG. 6, the through hole 341 extending in an arc shape has an inner end positioned near the opening edge of the continuous port 33, and an outer end positioned near the outer peripheral edge of the upper surface 31. It extends longer than the through hole 342 extending linearly. In addition, the through hole 342 extending linearly has an inner end positioned near the inner end of the arc-shaped through hole 341 in the vicinity of the opening edge of the continuous port 33, while the outer end thereof is It is located near the outer periphery of the upper surface 31. In the illustrated example, the inner end of the arc-shaped through hole 341 and the inner end of the linearly extending through hole 342 are not connected to the opening edge of the continuous port 33.

As described above, the through

holes

341 and 342 form

concave grooves

61 and 62 that are recessed from the upper surface 31 of the wear plate when the wear plate 3 is fixed to the bottom surface 117, respectively. Each groove is defined by the inner wall of the through hole and the bottom surface 117, and is recessed from the upper surface 31 of the wear plate 3 in the plate thickness direction. Each concave groove has a shape corresponding to the shape of the through hole. Specifically, the three through holes 341 extending in an arc shape form three concave grooves 61 extending in an arc shape, and the three through holes 342 extending linearly are three concave grooves 62 extending in a linear shape. Is forming. In addition, the number and form of a ditch | groove can be suitably set by changing the number and form of a through-hole.

The centrifugal pump 1 can crush foreign matter that has entered the storage chamber 110 by the

concave grooves

61 and 62 formed by the through

holes

341 and 342. As a result, foreign matter may be caught between the lower end surface of the blade 22 and the upper surface 31 of the wear plate 3 and the centrifugal pump 1 may be overloaded, or the centrifugal pump 1 may be activated. Such a situation is avoided. In other words, the foreign matter that has entered the gap between the lower end surface of the blade 22 and the upper surface 31 of the wear plate 3 is carried into the

concave grooves

61 and 62 by the blade 22, and relatively moves along the upper surface 31 there. When the blade 22 passes over the

concave grooves

61 and 62, it is crushed. As a result, the foreign matter is reduced, so that the foreign matter is prevented from being caught between the lower end surface of the blade 22 and the upper surface 31 of the wear plate 3. The crushed and reduced foreign matter is discharged out of the casing 11 together with water.

Here, as the centrifugal pump 1 is used, the lower end surface of the blade 22 comes into contact with the upper surface 31 of the wear plate 3, the blade 22 rotates while being in contact with the wear plate 3, and foreign matter is worn on the wear plate 3. The upper surface 31 of the wear plate 3 may be worn by moving the upper surface 31 of the wear plate 3. In addition, the through

holes

341 and 342 may wear due to the foreign matter entering the

concave grooves

61 and 62 coming into contact with the through

holes

341 and 342. When the upper surface 31 and the through

holes

341 and 342 of the wear plate 3 are worn like that, the user may remove the main body 114 of the casing 11 from the centrifugal pump 1 and replace the wear plate 3. In other words, conventionally, the lid configured separately from the casing body has been replaced. According to the above configuration, when the upper surface 31 of the wear plate 3 and the through

holes

341 and 342 are worn, Since only the thin plate-like wear plate 3 fixed to 117 needs to be replaced, the replacement cost is reduced compared to the conventional case of replacing the lid. As a result, the running cost of the centrifugal pump 1 is suppressed.

Furthermore, by providing the wear plate 3 attached and fixed to the casing 11, the material of the wear plate 3 can be changed according to the operating environment and use of the centrifugal pump 1, the material of the impeller 2, and the like. it can. This makes it possible to easily adjust the wear resistance of the

concave grooves

61 and 62 without changing the material of the casing 11.

Furthermore, the centrifugal pump 1 can use different wear plates with different numbers and forms of through holes according to the operating environment. As a result, foreign matter can be prevented from being caught and the centrifugal pump 1 can be operated stably.

Furthermore, the centrifugal pump 1 is provided with a plurality of types of casings according to the specifications such as the diameter of the centrifugal pump 1, but the wear plate 3 is provided for all or some of the plurality of types of casings. It can also be shared.

Furthermore, since this structure performs the process of penetrating and forming the through

holes

341 and 342 in the thin plate-shaped wear plate 3, it is easier to process than performing the process of forming a concave groove in the bottom surface 117 of the casing 11, and It will be cheaper.

In the above-described configuration, the through

holes

341 and 342 extend linearly, and the through

holes

341 and 342 form

concave grooves

61 and 62 extending in a groove shape. In this case, since the

concave grooves

61 and 62 extend over the wide radial range in which the lower end surface of the blade 22 moves relative to the extent that the

concave grooves

61 and 62 extend, the wear plate 3 is positioned. The foreign matter that reaches the vicinity is easily carried to the

concave grooves

61 and 62. Further, the crushed and reduced foreign matter is discharged out of the casing 11 together with water through the discharge port 113, or moves in the

concave grooves

61 and 62 due to a pressure difference in the casing 11. become. In the latter case, the foreign matter moving in the

concave grooves

61 and 62 is conveyed along the upper surface 31 of the wear plate 3 in the direction in which the

concave grooves

61 and 62 extend. Thus, the

concave grooves

61 and 62 suitable for crushing the foreign matter that has entered the storage chamber 110 or transporting the crushed foreign matter are formed.

In the above-described configuration, the through

holes

341 and 342 extend from the vicinity of the opening edge of the continuous port 33 on the upper surface 31 to the vicinity of the outer peripheral edge in the radial direction, and the through

holes

341 and 342 extend from the inner side in the radial direction to the outer side.

Grooves

61 and 62 extending in the direction are formed. In the casing 11, the pressure is relatively low at the inside in the radial direction and the pressure is relatively high at the outside in the radial direction, so that the foreign matter that has flowed into the casing 11 has a diameter due to the pressure difference. It may be carried inward in the direction. In this case, since the

concave grooves

61 and 62 extend from the inner side in the radial direction to the outer side, it is effective for smoothly conveying the foreign matter in the

concave grooves

61 and 62 from the outer side in the radial direction to the inner side. become.

In the above-described configuration, the concave groove 61 formed by the arc-shaped through hole 341 extends along the rotational direction of the impeller 2 from the radially inner side toward the outer side. Thereby, it becomes effective in crushing the foreign material carried to the concave groove 61.

In the above-described configuration, the concave groove 62 formed by the linearly extending through hole 342 extends along the direction against the rotation of the impeller 2 from the inner side to the outer side in the radial direction. . Thereby, since the biting of the foreign matter can be suppressed, it is effective in stably operating the centrifugal pump 1.

<Deformation example of wear plate>
In the embodiment, the wear plate 3 fixed to the bottom surface 117 has the three through holes 341 extending in an arc shape and the three through holes 342 extending in a straight line shape. However, the present invention is not limited to this. Absent. As described above, it is possible to change the arrangement and shape of the through holes, change the number, and combine the through holes having different arrangements and shapes as much as possible.

FIG. 7 shows various modifications of the wear plate 3.

FIG. 7 shows a first modification M1 of the wear plate 3 in the first row from the top and the first row from the left. The first modification M1 has three through holes arranged at an angular interval of about 120 ° around the rotation center axis. Each through-hole has a substantially C-shape between the vicinity of the opening edge and the outer periphery of the continuous port, and the direction in which the impeller 2 rotates as it moves away from the continuous port (clockwise in FIG. 7). Direction).

FIG. 7 shows a second modification M2 of the wear plate 3 in the first row from the top and the second row from the left. The second modification M2 has three through holes arranged at an angular interval of about 120 ° around the rotation center axis. Each through-hole extends linearly outward from the vicinity of the opening edge of the continuous port in the radial direction, and counteracts the rotation of the impeller 2 as it moves away from the continuous port (counterclockwise in FIG. 7). Direction).

FIG. 7 shows a third modification M3 of the wear plate 3 in the first row from the top and the third row from the left. The third modified example M3 has six through holes arranged at an angular interval of about 60 ° around the rotation center axis. Each through hole has the same shape as the through hole in the second modified example 2.

7 shows a fourth modification M4 of the wear plate 3 in the first row from the top and the fourth row from the left. The fourth modified example M4 has six through holes arranged at an angular interval of about 60 ° around the rotation center axis. Each through-hole extends in a circular arc shape from the vicinity of the opening edge of the continuous port toward the outside in the radial direction, and extends along the direction against the rotation of the impeller 2 as the distance from the continuous port increases.

Further, in the second row from the top in FIG. 7 and the first row from the left, a fifth modification M5 of the wear plate 3 is illustrated. The fifth modification M5 corresponds to a configuration in which the direction in which the through hole extends is reversed on the paper surface in the first modification M1. Specifically, although the three through holes according to the fifth modification M5 are substantially C-shaped as in the first modification M1, each through hole is an impeller as it moves away from the continuous port. It extends along the direction against the rotation of the impeller 2, not the direction in which the 2 rotates.

Similarly, the sixth modification M6 shown in the second row from the top in FIG. 7 and in the second column from the left corresponds to the configuration in which the direction in which the through hole extends is reversed in the second modification M2, and the upper part in FIG. The seventh modification M7 shown in the second row from the left and in the third column from the left corresponds to the configuration in which the direction in which the through hole extends is reversed in the third modification M3, and the second and left from the top in FIG. The eighth modification M8 shown in the fourth column from the top corresponds to the configuration in which the direction in which the through hole extends is reversed in the fourth modification M4.

Furthermore, a ninth modification M9 of the wear plate 3 is shown in the third row from the top and the first row from the left in FIG. On the upper surface of the ninth modification M9, three regions in which a large number of circular holes are formed are provided. Each region has a substantially fan shape extending from the vicinity of the continuous port to the outside in the radial direction, and each circular hole formed in each region has a smaller diameter than the continuous port. The three regions are arranged at an angular interval of about 120 ° around the rotation center axis.

FIG. 7 shows a tenth modification M10 of the wear plate 3 in the third row from the top and the second row from the left. The tenth modification M10 has six through holes that extend linearly from the vicinity of the continuous opening toward the outside in the radial direction. The six through-holes include three through-holes extending along the direction in which the impeller 2 rotates and three through-holes extending along the direction against the rotation of the impeller 2 as the distance from the continuous port increases. Yes. Among these, the three through-holes extending along the direction in which the impeller 2 rotates are arranged at an angular interval of about 120 ° around the rotation center axis, while the direction against the rotation of the impeller 2 The three through-holes extending along the direction are arranged between the through-holes extending along the direction in which the impeller 2 rotates, and are arranged at an angular interval of about 120 ° from each other. Then, the outer end of the through hole extending along the direction in which the impeller 2 rotates is close to the outer end of the through hole extending along the direction against the rotation of the impeller 2 as shown in FIG. Is arranged. On the upper surface of the tenth modification M10, a through hole extending along the direction in which the impeller 2 rotates, and a through hole adjacent to the through hole and extending in a direction against the rotation of the impeller 2 are provided. Three regions extending in a substantially fan shape from the vicinity of the continuous opening toward the outside in the radial direction are partitioned. In each region, a large number of circular holes having the same shape as the ninth modification M9 are formed.

FIG. 7 shows an eleventh modification M11 of the wear plate 3 in the third row from the top and the third row from the left. As in the tenth modification M10, the eleventh modification M11 has six through-holes extending linearly from the vicinity of the continuous opening toward the outside in the radial direction. The three through holes extending along the direction in which the impeller 2 rotates and the three through holes extending along the direction against the rotation of the impeller 2 are included as the distance from the continuous port increases. The inner end of the through hole extending along the direction in which the impeller 2 rotates is disposed so as to be close to the inner end of the through hole extending along the direction against the rotation of the impeller 2. Similar to the eleventh modification, the upper surface of the tenth modification M10 has a through hole extending along the direction in which the impeller 2 rotates, and a direction adjacent to the through hole and against the rotation of the impeller 2. By the through-holes extending along the three regions, three regions extending in a substantially fan shape from the vicinity of the continuous port toward the outside in the radial direction are partitioned. A large number of circular holes having the same shape as the ninth modification M9 and the tenth modification M10 are formed in one of the three regions.

FIG. 7 shows a twelfth modification M12 of the wear plate 3 in the third row from the top and the fourth row from the left. This twelfth modification M12 has three through-holes extending in an arc shape along the direction against the rotation of the impeller 2 as it moves away from the continuous port, similarly to the through-

holes

341 and 342 according to the embodiment, It has three through-holes extending linearly along the direction in which the impeller 2 rotates as the distance from the continuous port increases. Among these, the three through holes extending in an arc shape are arranged at an angular interval of approximately 120 ° around the rotation center axis, while the three through holes extending in a straight line each extend in an arc shape. It arrange | positions between through-holes, and is mutually arrange | positioned at intervals of about 120 degrees. Furthermore, the inner end of the through-hole extending in an arc shape is located near the opening edge of the continuous port, while the outer end is located near the outer peripheral edge of the upper surface. Further, the through hole extending linearly has its inner end positioned near the inner edge of the circular hole extending in the vicinity of the opening edge of the continuous opening, while its outer end is located on the upper surface. In the vicinity of the outer peripheral edge, it is positioned near the outer end of another through-hole extending in an arc shape.

Further, in the fourth row from the top in FIG. 7 and the first row from the left, a thirteenth modification M13 of the wear plate 3 is illustrated. The thirteenth modification M13 has one through hole. The through hole extends in a spiral shape from the vicinity of the opening edge of the continuous port toward the outside in the radial direction, and extends along the direction in which the impeller 2 rotates as the distance from the continuous port increases.

Further, a fourteenth modification M14 of the wear plate 3 is shown in the fourth row from the top and the second row from the left in FIG. The fourteenth modified example M14 includes three through-holes extending in an arc shape along the direction in which the impeller 2 rotates as the distance from the continuous port 33 increases, similar to the through-

holes

341 and 342 according to the above embodiment. It has three through-holes extending linearly along the direction against the rotation of the impeller 2 as it moves away from the continuous port 33. Unlike the inner ends of the through

holes

341 and 342 according to the embodiment, the inner ends of the through holes according to the fourteenth modification M14 are both connected to the opening edge of the continuous port.

In addition, the through holes shown in M1 to M14 in FIGS. 6 and 7 can be combined in a possible range other than shown.

<Other embodiments>
In the above-described configuration, the blade 22 of the centrifugal impeller 2 is configured by a single blade. However, the technology disclosed herein can be widely applied to centrifugal pumps including a semi-open centrifugal impeller.

DESCRIPTION OF SYMBOLS 1 Centrifugal pump 11 Casing 110 Accommodating chamber 111 Communication port 117 Bottom surface 2 Centrifugal impeller 21 Rear surface shroud (shroud)
22 Blade 3 Wear plate 31 Upper surface of wear plate (relative surface)
33 Continuous port 341 Through hole 342 Through hole 4 Suction port 61 Concave groove (concave portion)
62 Groove (concave)
X rotation center axis

Claims

A semi-open type centrifugal impeller having a shroud formed in a disk shape and a blade erected in the direction of the rotation center axis with respect to the shroud;
A casing having a storage chamber for storing the centrifugal impeller,
The casing has a bottom surface formed with a communication port communicating with the storage chamber.
A wear plate that is disposed between the bottom surface and the standing end surface of the blade and that has a relative surface facing the standing end surface with a predetermined gap in the direction of the rotation center axis is fixed to the bottom surface. And
The wear plate is continuous with the communication port, is integrated with the communication port and constitutes a suction port into the storage chamber, and passes through the wear plate in the plate thickness direction. A centrifugal pump comprising: at least one through hole that forms a recess that is recessed from the relative surface of the wear plate when fixed to the bottom surface.
The centrifugal pump according to claim 1,
At least one of the through holes extends in a linear shape.
The centrifugal pump according to claim 2,
At least one of the through holes extends from the vicinity of the continuous port toward the outside in the radial direction.
The centrifugal pump according to claim 3,
At least one of the through holes extends along a direction in which the centrifugal impeller rotates as the distance from the continuous port increases.
The centrifugal pump according to claim 3 or claim 4,
At least one of the through holes extends in a direction against the rotation of the centrifugal impeller as the distance from the continuous port increases.
The centrifugal pump according to claim 1,
The centrifugal pump, wherein the through hole extends in a spiral shape.
The centrifugal pump according to any one of claims 1 to 6,
The centrifugal pump having one through hole.
The centrifugal pump according to any one of claims 1 to 7,
The centrifugal pump, wherein the through hole is connected to the continuous port.