JP6523917B2 - Centrifugal pump - Google Patents

Description

  The present invention relates to a centrifugal pump.

Conventionally, in a centrifugal pump having a closed type impeller in a casing, as a measure to reduce the axial thrust generated in the impeller, the inner wall surface of the casing facing the side plate of the impeller radially from the rotating shaft side of the impeller in the centrifugal direction There is known one having an extending groove and a fixed blade (see, for example, Patent Documents 1 and 2).
In such a centrifugal pump, the speed of the swirling flow of the fluid flowing in the gap (leak flow path) formed between the side plate of the impeller and the inner wall surface of the casing is reduced by the groove and the fixed blade. Thereby, the centrifugal pump reduces the axial thrust by increasing the pressure in the gap, and reduces the load on the thrust bearing.

JP-A-9-317685 U.S. Pat. No. 5,320,482

However, in the axial thrust countermeasure in the conventional centrifugal pump (for example, see Patent Documents 1 and 2), the above-mentioned grooves and fixed blades increase the frictional resistance between the fluid in the gap (leakage flow path) and the rotating impeller. Let That is, in the conventional countermeasure against axial thrust, since the axial power of the impeller is increased, the pump efficiency obtained by dividing the product of the fluid flow rate and the head by the axial power is reduced.
Moreover, in the conventional centrifugal pump (for example, refer patent documents 1, 2), a manufacturing process becomes complicated by formation of a radial groove, attachment of a fixed blade, etc.

  Therefore, an object of the present invention is to provide a centrifugal pump having a simple structure as compared with the prior art and capable of reducing axial thrust while maintaining good pump efficiency.

The present invention, which solves the above problems, has an impeller having a fluid pressure rising channel between a main plate and a side plate, a casing for housing the impeller inside, and a fluid discharge port of the pressure channel on the outer peripheral side of the impeller. A centrifugal pump having a main flow path of fluid formed in the casing so as to face, formed between a plate surface of the side plate and a first opposing surface of the casing facing the plate surface Gap between the side chamber and the second opposing surface of the casing that faces the outer peripheral end face of the side plate and the outer peripheral end face so as to surround the entire outer peripheral end face, When provided with, on the second opposing surface of the casing that forms the gap, the side chamber with the groove so as to extend between the main flow path is formed, the groove is circumferential of the second opposing surface Equally spaced along the direction Formed with a plurality, in the radial direction of the outside of the impeller, comprising a diffuser having a plurality of guide vanes, the groove has a feature that it is formed so as to be adjacent in the radial direction of the inner end of the guide vanes Do.

  According to the present invention, it is possible to provide a centrifugal pump which has a simple structure as compared with the prior art and can reduce axial thrust while maintaining good pump efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS It is a cross-sectional view which shows roughly the whole structure of the centrifugal pump which concerns on embodiment of this invention. It is the partial expansion longitudinal cross-sectional view which partially expanded the impeller vicinity of the centrifugal pump which concerns on embodiment of this invention. It is the III-III fragmentary sectional view of FIG. It is a graph which shows the relationship between the position of the axial direction from the entrance of the 1st crevice of the centrifugal pump shown in Drawing 2 to the exit of the 1st crevice, and the turning speed of the leak flow in the 1st crevice. It is a graph which shows the relationship of the position of the radial direction from the inlet of the 1st side chamber of the centrifugal pump shown in FIG. 2 to the exit of a 1st side chamber, and the pressure of a 1st side chamber. It is the partial expansion longitudinal cross-sectional view which partially expanded the impeller vicinity of the multistage centrifugal diffuser pump which concerns on other embodiment of this invention. It is VII-VII partial sectional drawing of FIG. It is a graph which shows the relationship between the position of the axial direction from the entrance of the 1st crevice of a centrifugal pump shown in Drawing 6 to the exit of the 1st crevice, and the turning speed of the leak flow in the 1st crevice. It is structure explanatory drawing of the centrifugal pump which a groove | channel inclines. It is structure explanatory drawing which shows the modification of a groove | channel. It is structure explanatory drawing which shows the modification of a groove | channel. It is structure explanatory drawing which shows the other modification of a groove, and is a figure corresponding to the partial expanded sectional view of the groove | channel vicinity in the centrifugal pump of FIG. It is a XIII-XIII fragmentary sectional view of FIG. It is structure explanatory drawing which shows the other modification of a groove | channel, and is a figure corresponding to FIG.

Embodiments of the present invention will be described in detail with reference to the drawings as appropriate.
The centrifugal pump according to the present embodiment is different from the axial thrust measures of the conventional centrifugal pump (see, for example, Patent Documents 1 and 2), and the fluid in the leakage flow channel is not provided without the radial grooves and the fixed blades. It was configured to suppress the turning of the That is, the axial thrust countermeasure of the centrifugal pump according to the present embodiment is between the leakage flow passage (first side chamber described later) and the main flow passage (hereinafter simply referred to as “main flow passage”) facing the discharge port of the fluid of the impeller. The main feature is that the inner wall surface of the casing has a groove so as to extend in

  In this embodiment, an example in which the present invention is applied to a centrifugal pump having a volute (spiral casing) will be described. In addition, about the diffuser pump which has a guide blade, a multistage centrifugal diffuser pump is demonstrated to an example by the column of other embodiment.

FIG. 1 is a cross-sectional view schematically showing an overall configuration of a centrifugal pump 100 according to an embodiment of the present invention. In FIG. 1, the side plate 13 (see FIG. 2) of the impeller 10 is omitted for convenience of drawing.
FIG. 2 is a partially enlarged longitudinal sectional view in which the vicinity of the impeller 10 of the centrifugal pump 100 according to the present embodiment is partially enlarged, and shows the upper half side bordering on the center line of the main shaft 17.
Note that the front and back directions in the following description correspond to the side plate 13 (see FIG. 2) described later, also referred to as a front shroud, and the main plate 11 (see FIG. 2) described hereinafter as a rear shroud. Based on the front and back direction shown by the arrow.

As shown in FIG. 1, the centrifugal pump 100 in the present embodiment has a main shaft 17 rotated by a prime mover (not shown), an impeller (centrifugal impeller) 10 rotationally driven by the main shaft 17, and an impeller 10 inside. And a casing 20 housed in the housing.
In FIG. 1, reference numeral 11 is a main plate of the impeller 10, reference numeral 12 is a blade of the impeller 10, reference numeral 23 is an inlet of fluid in the centrifugal pump 100, and reference numeral 25 is fluid of the centrifugal pump 100. It is an outlet, code 24 is volute, code R is the rotation direction of impeller 10.

  As shown in FIG. 2, the impeller 10 in the present embodiment is a closed type, and includes a main plate 11, blades 12 and side plates 13 (not shown in FIG. 1).

  The main plate 11 is formed of a substantially disk-shaped disk disposed concentrically with the main shaft 17 and formed so as to rotate in synchronization with the main shaft 17. The main plate 11 is also referred to as a rear shroud as described above. A side plate 13 to be described later is disposed on the main plate 11 so as to be opposed to the main plate 11, and between the side plate 13 and the side plate 13, a pressure-rising flow path 14 of fluid to be pumped is formed.

The main plate 11 in the present embodiment divides the inlet of the pressurizing flow passage 14 opened in the extension direction of the main shaft 17, that is, the suction port 15 of the fluid of the impeller 10 together with the main shaft 17 and the side plate 13, and opens in the centrifugal direction. And the discharge port 16 of the fluid of the impeller 10 is partitioned. The fluid discharge port 16 corresponds to the "fluid discharge port" in the claims.
The surface on the side plate 13 side in the main plate 11 of the present embodiment is a curved surface that gradually approaches the centrifugal direction of the impeller 10 as it goes rearward from the suction port 15 on the front side.

The side plate 13 is composed of a substantially annular member disposed concentrically with the main shaft 17 and disposed concentrically with the main shaft 17 so as to face the main plate 11 as described above.
The opposing surface of the side plate 13 with the main plate 11 is a curved surface that gradually approaches the centrifugal direction of the impeller 10 as it goes rearward from the suction port 15 so as to correspond to the above-described curved surface of the main plate 11.
As described above, the side plate 13 and the main plate 11 form a pressure increasing flow path 14 of the fluid in the impeller 10. Further, as described above, the side plate 13 forms a fluid suction port 15 between the main shaft 17 and the main plate 11 on the front side of the impeller 10, and the fluid discharge port 16 between the main plate 11 and the outer periphery of the impeller 10. Form. The side plate 13 is also referred to as a front shroud as described above, and holds the blades 12 between itself and the main plate 11.

As shown in FIG. 1, the blades 12 are formed of a plate extending radially outward from the axial center side, and a plurality of the blades 12 are arranged at equal intervals in the circumferential direction.
The impeller 10 in the present embodiment assumes that the six blades 12 curved in the length direction are disposed in a spiral shape, but the number of the blades 12 is not limited to this. It may be 5 or less, 7 or more. By the way, although it is assumed that the blade 12 is curved so that the middle portion becomes convex in the rotational direction of the impeller 10 shown by the arrow R in FIG. 1, it is also possible to use a blade 12 which is not curved .
The vanes 12 divide the space between the main plate 11 (see FIG. 2) and the side plate 13 at equal intervals in the circumferential direction to form a pressurizing flow passage 14.

  The casing 20 rotatably supports the main shaft 17 via a plurality of bearings (not shown). A sealing member (not shown) such as a mechanical seal is provided between the casing 20 and the main shaft 17 in order to prevent fluid leakage.

  Further, the casing 20 is formed with a supply passage 21 for supplying a fluid to the impeller 10 through the suction port 15 and the above-mentioned main flow passage 22 for delivering the fluid discharged from the discharge port 16 of the impeller 10 . Incidentally, in the centrifugal pump 100 (swirl pump) in the present embodiment, the supply path 21 is in communication with the inlet 23 (see FIG. 1) of the centrifugal pump 100. Further, the main flow passage 22 communicates with the outlet 25 (see FIG. 1) through the volute 24 of the centrifugal pump 100.

The casing 20 also has an opposing surface 20 a that faces the plate surface of the side plate 13 of the impeller 10. The facing surface 20a corresponds to the "first facing surface" in the claims.
The facing surface 20 a forms a first side chamber 30 between itself and the plate surface of the side plate 13 of the impeller 10. The first side chamber 30 corresponds to the "side chamber" in the claims.
Further, the casing 20 forms a second side chamber 31 between itself and the plate surface of the main plate 11 of the impeller 10.

The casing 20 also has an opposing surface 20 b that faces the outer peripheral end surface of the side plate 13 of the impeller 10. The facing surface 20 b corresponds to the “second facing surface” in the claims.
The facing surface 20 b forms a first gap S <b> 1 between it and the outer peripheral end face of the side plate 13 of the impeller 10.
The first side chamber 30 communicates with the main flow path 22 via the first gap S1. The casing 20 also has a cylindrical portion 36 surrounding the suction port 15 around the main shaft 17 and internally fitting the front outer peripheral portion of the side plate 13. The first side chamber 30 communicates with the supply passage 21 via a second gap S2 formed between the front outer periphery of the side plate 13 and the cylindrical portion 36 of the casing 20.

  The second side chamber 31 communicates with the main flow passage 22 via a third gap S3 formed between the outer peripheral end face of the main plate 11 of the impeller 10 and the casing 20.

And the centrifugal pump 100 of this embodiment has the groove part 33 in the opposing surface 20b of the casing 20 so that it may extend between the 1st side chamber 30 and the main flow path 22 as mentioned above. The groove 33 in the present embodiment is formed on the facing surface 20 b along the extending direction of the main shaft 17.
In FIG. 2, the arrow indicated by reference numeral 34 a indicates the flow of fluid from the supply passage 21 to the suction port 15, and the arrow indicated by reference numeral 34 b indicates the flow of fluid from the pressurizing passage 14 to the main passage 22. The arrow indicated by reference numeral 34 c represents the “leakage flow” that flows through the first side chamber 30 described later.

FIG. 3 is a III-III partial cross-sectional view of FIG. In FIG. 3, reference numeral 12 is a blade of the impeller 10, reference numeral 13 is a side plate, and reference numeral 20 is a casing.
As shown in FIG. 3, the groove 33 in the present embodiment has a rectangular shape in a cross-sectional view, and the groove width is set to be longer than the depth of the groove 33.
A plurality of grooves 33 are formed at equal intervals along the circumferential direction of the facing surface 20 b (second facing surface) of the casing 20 which is separated from the end face of the outer peripheral portion of the side plate 13 via the first gap S1. In the present embodiment, the casing 20 is assumed to have nine grooves 33. However, the present invention may be configured to have eight or less or ten or more grooves 33.

  The centrifugal pump 100 as described above can be manufactured by attaching the impeller 10 to the casing 20 having the groove 33. At this time, for example, the groove 33 can be integrally formed with the groove 33 and the casing 20 by casting or the like, or can be formed in the predetermined casing base by cutting or the like by additional processing.

Next, the function and effect of the centrifugal pump 100 according to the present embodiment will be described mainly with reference to FIG.
In the centrifugal pump 100, when the impeller 10 is rotationally driven via the main shaft 17 by a prime mover (not shown), energy is applied to the fluid in the pressure raising flow path 14 to pressure the fluid. The main flow path 22 is a stationary flow path and reduces the velocity of the fluid provided by the impeller 10 to restore the pressure.

  Unlike the centrifugal pump 100 according to the present embodiment shown in FIG. 2, a centrifugal pump (not shown) of Comparative Example 1 having no groove 33 is assumed here. The centrifugal pump of Comparative Example 1 is configured in the same manner as the centrifugal pump 100 according to the present embodiment, except that the groove portion 33 is not provided. The centrifugal pump of Comparative Example 1 described below will be described with reference to FIG. 2 in which the groove 33 is not provided.

  In the centrifugal pump of Comparative Example 1, the fluid sucked through the suction port 15 is discharged from the discharge port 16 to the main flow path 22 by the impeller 10 which is rotationally driven. At this time, a part of the discharged fluid flows into the first side chamber 30 through the first gap S1 as a leak flow 34c.

  Then, the leaked flow 34 c flows from the first side chamber 30 toward the main shaft 17, flows into the supply passage 21 through the second gap S 2, and is sucked into the impeller 10 through the suction port 15 again. That is, the first gap S1, the first side chamber 30, and the second gap S2 form a fluid leak flow path from the main flow path 22 to the supply path 21. In the centrifugal pump of Comparative Example 1 as described above, the fluid having a high speed of the swirling flow in the vicinity of the discharge port 16 of the impeller 10 flows into the first side chamber 30 as described above. In the first side chamber 30, the swirling speed of the fluid (leakage flow 34c) significantly increases, and the pressure in the first side chamber 30 decreases.

  On the other hand, in the centrifugal pump 100 according to the present embodiment, the fluid having a high speed of the swirling flow in the vicinity of the discharge port 16 flows into the first gap S1, and then a part of the fluid flows in the groove 33 and the other A portion of the fluid flows across the groove 33. Thus, the groove 33 acts as a resistance to turning, so that turning of the fluid flowing into the first gap S1 is suppressed. As a result, the swirling speed of the fluid (leakage flow 34 c) in the first side chamber 30 is reduced, and the pressure in the first side chamber 30 is increased.

Next, verification of the operation and effect performed on the centrifugal pumps 100 of Example 1 and Comparative Example 1 will be described.
In this verification, in the axial direction of the first gap S1 shown in FIG. 2, the swirling speed of the leaked flow 34c from the inlet A _IN to the outlet A _OUT of the leaked flow 34c was determined by fluid analysis. The results are shown in FIG.
4 shows an inlet A _IN of the first gap S1 of the centrifugal pump 100 shown in FIG. 2 (referred to as a gap inlet A _{IN in} FIG. 4) to an outlet A _OUT (shown as a gap outlet A _{OUT in} FIG. 4) It is a graph which shows the relationship between the position of an axial direction, and the turning speed (it is described as turning speed in FIG. 4) of the leakage flow 34c in 1st clearance gap S1.

Further, in the fluid analysis, the pressure of the first side chamber 30 from the inlet B _IN of the leakage flow 34 c to the outlet B _OUT was obtained in the radial direction of the first side chamber 30 shown in FIG. The results are shown in FIG.
5 shows an inlet B _IN of the first side chamber 30 of the centrifugal pump 100 shown in FIG. 2 (referred to as a side chamber inlet B _{IN in} FIG. 5) to an outlet B _OUT of the first side chamber 30 (in FIG. 5 a side chamber outlet B _OUT 5 is a graph showing the relationship between the position in the radial direction up to) and the pressure of the first side chamber 30 (described as the pressure in the side chamber in FIG. 5).

As shown in FIG. 4, in Comparative Example 1 (without a groove) indicated by a broken line, the swirling speed of the leakage flow 34 c from the inlet A _IN of the first gap S1 toward the outlet A _OUT of the first gap S1 is high. Further, the turning speed tends to increase as it goes to the first side room 30 (as it goes to the outlet A _OUT ).
On the other hand, in Example 1 (with a groove) shown by a solid line, the swirling speed of the leak flow 34c is slower than that of Comparative Example 1 (without a groove). Specifically, the swing speed of Example 1 in the vicinity of the first side chamber 30 (near the outlet A _OUT ) is 65% or less of that in Comparative Example 1.

Further, as shown in FIG. 5, the pressure of the first side chamber 30 in the first embodiment (dovetail groove) indicated by a solid line, as compared with Comparative Example 1 (no groove), the outlet from the inlet B _IN of the first side chamber 30 B It has been verified to increase throughout _OUT .
That is, the centrifugal pump 100 of the present embodiment increases the pressure of the first side chamber 30 by having the groove 33 on the inner wall surface of the casing 20 forming the first gap S1, and the impeller 10 is on the suction port 15 side (front side). Reduce the axial thrust that is biased by
According to the centrifugal pump 100 of the present embodiment, the load on the thrust bearing can be reduced.

  Moreover, the centrifugal pump 100 of this embodiment can be manufactured by forming the groove part 33 with respect to the centrifugal pump (For example, centrifugal pump like said comparison 1) of basic structure. Therefore, the centrifugal pump 100 of the present embodiment can be manufactured without making a major design change with respect to the basic structure centrifugal pump.

  Further, since the groove 33 of the centrifugal pump 100 is formed on the facing surface 20b of the casing 20 along the extending direction of the main shaft 17, unlike the radial groove of the conventional centrifugal pump 100, it is by a simple cutting tool It can be easily formed. Therefore, according to the centrifugal pump 100 of the present embodiment, the manufacturing process can be simplified, and the manufacturing cost can be reduced.

  Further, in the method of manufacturing the centrifugal pump 100 described above, one in which the groove portion 33 is formed by additional processing can be applied also as a method of adjusting the axial thrust. In other words, the centrifugal pump 100 of the present embodiment has an adjustable structure of axial thrust.

As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, It can implement with a various form.
Although the said embodiment demonstrated the spiral pump which has a volute (volute casing) of a spiral type, the diffuser pump which has guide vanes next is demonstrated. Here, a multistage centrifugal diffuser pump will be described as an example. In the following other embodiments, the same components as those of the above-described embodiment are denoted by the same reference numerals and the detailed description thereof will be omitted.

FIG. 6 is a partially enlarged longitudinal sectional view partially enlarging the vicinity of the impeller 10 of a centrifugal pump 100 (multistage centrifugal diffuser pump) according to another embodiment of the present invention.
As shown in FIG. 6, the centrifugal pump 100 has an outer casing (not shown) provided with an inlet and an outlet for fluid and an inner casing 20 disposed inside the outer casing. The inner casing 20 corresponds to a "casing" in the claims. Hereinafter, the inner casing 20 is simply referred to as a "casing 20".

  The centrifugal pump 100 also has a main shaft 17 disposed to penetrate the casing 20 and a plurality of stages of impellers 10 fixed to the main shaft 17. Although only a part of the impeller 10 is partially shown in FIG. 6 and the impeller 10 in this embodiment is assumed to have about six stages, it is not limited to this. Absent.

The casing 20 is provided with an internal space in which the diameter reduction and the diameter increase are repeated according to the arrangement of the impeller 10.
Further, in the casing 20, a communication passage 40 connecting the discharge port 16 and the suction port 15 of the adjacent impellers 10 is formed. Incidentally, the suction port 15 of the impeller 10 located most upstream among the impellers 10 having a plurality of stages communicates with the fluid inlet (not shown) in the centrifugal pump 100 and discharges the impeller 10 located most downstream. The outlet 16 is in communication with the outlet (not shown) of the fluid in the centrifugal pump 100.

  The communication passage 40 includes a supply passage 21 for introducing a fluid into the pressurizing passage 14 formed between the side plate 13 of the impeller 10 and the main plate 11, and a diffuser passage 41 into which the fluid is introduced from the pressurizing passage 14. It has a return flow channel 42 for allowing the fluid to flow from the diffuser flow channel 41 side to the supply flow channel 21 side, and a water return blade 50 provided in the return flow channel 42.

The supply path 21 is a flow path which changes the direction of the fluid in the axial direction immediately before the impeller 10 after flowing the fluid from the outer side in the radial direction toward the inner side in the radial direction.
The diffuser channel 41 communicates with the pressurizing channel 14 on the radially inner side, and circulates the fluid pressurized by the impeller 10 radially outward. A plurality of guide vanes 43 are arranged at equal intervals in the circumferential direction around the main shaft 17 in the diffuser flow path 41. The guide vanes 43 are so-called diffuser vanes and constitute a diffuser. Incidentally, the inclination of the guide vanes 43 arranged in the circumferential direction is opposite to the inclination of the vanes 12 of the impeller 10 as described later (see FIG. 7).
One end side of the return flow path 42 communicates with the diffuser flow path 41, and the other end side communicates with the supply path 21 via the water return blade 50.

The impeller 10 is a closed type, and includes a main plate 11, blades 12 and a side plate 13.
The first side chamber 30 communicates with the main flow passage 22 via a first gap S1 formed between the outer peripheral end face of the side plate 13 of the impeller 10 and the casing 20. Further, the first side chamber 30 communicates with the supply passage 21 via a second gap S2 formed between the front outer periphery of the side plate 13 and the cylindrical portion 36 of the casing 20.
And this centrifugal pump 100 has the groove part 33 in the opposing surface 20b (2nd opposing surface) of the casing 20 so that it may extend between the 1st side chamber 30 and the main flow path 22 as mentioned above.
The groove 33 is formed in the facing surface 20 b of the casing 20 along the extending direction of the main shaft 17.
In FIG. 6, the arrow indicated by reference numeral 34a indicates the flow of fluid from the supply passage 21 to the suction port 15, and the arrow indicated by reference numeral 34c indicates “leakage” flowing from the main flow passage 22 to the first side chamber 30. Represents the flow.

7 is a partial cross-sectional view taken along line VII-VII of FIG. In FIG. 7, reference numeral 12 is a blade of the impeller 10, reference numeral 13 is a side plate, reference numeral 20 is a casing, and reference numeral 43 is a guide blade.
As shown in FIG. 7, the groove 33 in the present embodiment has a rectangular shape in cross section, and the groove width is set to be longer than the depth of the groove 33.
The groove portions 33 are formed at equal intervals along the circumferential direction of the inner peripheral surface of the casing 20 which is separated from the end surface of the outer peripheral portion of the side plate 13 via the first gap S1. In the present embodiment, the casing 20 is assumed to have nine grooves 33. However, the present invention may be configured to have eight or less or ten or more grooves 33.

Further, in the relationship between the position of the guide blade 43 and the position of the groove 33, the groove 33 is preferably formed to be close to the radially inner end 43a of the guide blade 43.
In particular, it is desirable that the end 33a on the front side in the rotational direction R of the impeller 10 be formed to be close to the inner tip 43a of the guide blade 43 among both end portions in the circumferential direction of the groove 33.

Further, assuming that the angle at which the inner tips 43a of the guide vanes 43, 43 adjacent in the circumferential direction open about the rotation center (not shown) of the impeller 10 is θ, the circumferential position of the front end 33a of the groove 33 Is more preferably within the range of ± θ / 4 with respect to the position of the inner tip 43a of the guide vane 43. A more desirable circumferential position of the front end 33a of the groove 33 is a line connecting the center of rotation of the impeller 10 and the inner tip 43a of the guide vane 43, although not shown.
Further, in the relationship between the positions of the guide vanes 43, 43 adjacent in the circumferential direction and the circumferential width W of the groove 33, the width W of the groove 33 is preferably half or less of the angle θ (W ≦ θ / 2). .

  In such a centrifugal pump 100 (multistage centrifugal diffuser pump), the fluid is boosted stepwise by the impellers 10 (see FIG. 6) provided in multiple stages via the communication passage 40 and the water return vanes 50 (see FIG. 6). Ru. At this time, the centrifugal pump 100 has the groove 33 (see FIG. 7), thereby providing the guide vanes 43 in addition to the same function and effect as the centrifugal pump 100 according to the embodiment. Play an important effect.

As shown in FIG. 6, in the centrifugal pump 100, fluid is discharged from the pressure rising flow passage 14 of the rotating impeller 10 to the diffuser flow passage 41 of the casing 20. Thereafter, when operating in a low flow rate region, the fluid collides with the guide vanes 43 to cause backflow of the fluid whose swirl is suppressed.
And this back flow with slow swirling speed forms a leak flow 34c together with the flow from the main flow passage 22 toward the first gap S1. According to such a centrifugal pump 100, by causing the backflow with a slow swing speed generated by the guide vanes 43 to flow into the groove 33, the swing speed of the fluid (leakage flow 34c) in the first side chamber 30 is efficiently reduced. be able to.

  In addition, the centrifugal pump 100 causes a reverse flow with a low rotational speed generated by the guide vanes 43 to flow into the groove portion 33. As a result, the centrifugal pump 100 can improve the reduction effect of the axial thrust in an operation in a low flow rate region where backflow occurs, as compared with the one without the guide vanes 43. Further, the centrifugal pump 100 suppresses the axial thrust reduction effect near the flow rate at the highest efficiency point while securing a sufficient axial thrust reduction effect in the small flow rate region. According to such a centrifugal pump 100, by reducing the friction between the fluid in the first side chamber 30 and the impeller 10 in the vicinity of the highest efficiency point flow rate, it is possible to design that the reduction of the pump efficiency due to the axial thrust reduction can be suppressed. Become.

Next, the operation performed to Example 2 which is centrifugal pump 100 (refer to Drawing 6) which has guide blade 43, and comparative example 2 which assumed the same composition as Example 2 except not having slot 33 is carried out. The verification of the effect by fluid analysis is described. About the centrifugal pump of the comparative example 2, FIG. 6 in which the groove part 33 was not provided is referred.
In this verification, in the axial direction of the first gap S1 shown in FIG. 6, the swirling speed of the leaked flow 34c from the inlet C _IN of the leaked flow 34c to the outlet C _OUT was measured. The results are shown in FIG.
FIG. 8 shows the inlet C _IN of the first gap S1 of the centrifugal pump 100 shown in FIG. 6 (referred to as the gap inlet C _{IN in} FIG. 8) to the outlet C _OUT of the first gap S1 (in FIG. 8 the gap outlet C _OUT 8 is a graph showing the relationship between the axial position up to (noted) and the swirling speed of the leaked flow 34c in the first gap S1 (referred to as the swirling speed in FIG. 8).

As shown in FIG. 8, in Comparative Example 2 (without a groove) indicated by a broken line, the swirling speed of the leakage flow 34c from the inlet C _IN of the first gap S1 toward the outlet C _OUT of the first gap S1 is high. Further, the turning speed tends to increase as it goes to the first side chamber 30 side (as it goes to the outlet C _OUT ). That is, the leaked flow 34 c whose swirling speed is suppressed by the guide vanes 43 comes to have a quick turn again while passing through the first gap S 1.
On the other hand, in Example 2 (with a groove) shown by a solid line, it was verified that the outlet C _OUT was reached while the swirling speed of the leaked flow 34 c was slower compared to Comparative Example 2 (without a groove).

  In the above embodiment, the centrifugal pump 100 in which the groove 33 extends in the axial direction has been described, but in the present invention, the groove 33 extends so as to be inclined with respect to the axial direction. You can also.

FIG. 9 is a configuration explanatory view of the centrifugal pump 100 in which the groove 33 is inclined. 9 is a partial cross-sectional view corresponding to the IX-IX cross section of FIG.
In FIG. 9, reference numeral 20 denotes a casing, reference numeral 33 denotes a groove, and reference numeral R denotes a rotation direction of the impeller 10.
As shown in FIG. 9, in the centrifugal pump 100, the extending direction of the groove 33 is inclined with respect to the axial direction (not shown) of the centrifugal pump 100, so that The extending direction is inclined. More specifically, the groove 33 is formed such that the extending direction of the groove 33 forms an acute angle with the rotational direction R of the impeller 10.

  According to such a centrifugal pump 100, a leakage flow with a small swirl can be efficiently introduced into the first side chamber 30 (see FIG. 6) through the groove portion 33, so that the axial thrust reduction effect is more remarkable. Appear in

In addition, although the groove part 33 shown in FIG. 9 inclines so that the extension direction of the groove part 33 makes an acute angle with respect to the rotation direction R of the impeller 10, it can also be set as an inclination so as to make an obtuse angle. .
Since the angle between the vector direction of the leakage flow and the extending direction of the groove 33 is closer to a right angle as compared with an acute angle, the groove 33 having such an obtuse angle makes the leakage flow The turning speed can be further reduced. Thus, the centrifugal pump 100 can further reduce the axial thrust.

  Moreover, although the cross-sectional shape of the groove part 33 demonstrated the rectangular shape in the said embodiment, the cross-sectional shape of the groove part 33 may be made into polygonal shape other than a rectangle, or circular arc shapes, such as semicircle or semielliptic it can.

FIG.10 and FIG.11 is structure explanatory drawing which shows the modification of the groove part 33, and is a fragmentary sectional view corresponding to the VII-VII cross section of FIG.
10 and 11, reference numeral 20 denotes a casing, reference numeral 33 denotes a groove, reference numeral 12 denotes a blade of the impeller 10, reference numeral 13 denotes a side plate of the impeller 10, and reference numeral 43 denotes a guide blade.

The cross-sectional shape of the groove 33 in the centrifugal pump 100 shown in FIG. 10 is triangular, and the cross-sectional shape of the groove 33 in the centrifugal pump 100 shown in FIG. 11 is semicircular.
According to the centrifugal pump 100 having such a groove 33, the groove 33 can be easily formed by cutting the casing base (not shown) with a simple cutting tool. Incidentally, as a cutting tool, a file, a drill, etc. are mentioned, for example.

FIG. 12 is a configuration explanatory view showing another modification of the groove portion 33, and is a view corresponding to a partial enlarged cross-sectional view in the vicinity of the groove in the centrifugal pump of FIG. 13 is a partial cross-sectional view of XIII-XIII in FIG.
As shown in FIG.12 and FIG.13, the casing 20 (refer FIG. 12) has the groove part formation member 38 in which the groove part 33 was formed. The groove forming member 38 is fitted into the casing 20. In addition, the code | symbol 30 is a 1st side chamber in FIG. In FIG. 12 and FIG. 13, reference numeral 12 is a blade of the impeller 10, reference numeral 13 is a side plate of the impeller 10, and reference numeral 43 is a guide blade.

  More specifically, as shown in FIG. 12, the casing 20 includes a casing main body 20c and a ring member 20d disposed so as to surround the outer peripheral end of the side plate 13 of the impeller 10 with the first gap S1 open. Is configured.

  And the groove part formation member 38 is engage | inserted and arrange | positioned by the inner peripheral side of the ring member 20d. The groove portion forming member 38 is formed in an L shape in cross section so as to prevent the ring member 20d from coming off.

  As shown in FIG. 13, a plurality of groove forming members 38 are arranged along the circumferential direction on the inner peripheral side of the casing 20, and the groove forming members 38 having the grooves 33 are fitted independently of each other.

FIG. 14 is a configuration explanatory view showing a further modified example of the groove 33, and corresponds to FIG.
As shown in FIG. 14, the groove 33 is formed in the groove forming member 39. Unlike the groove forming member 38 separately formed for each of the plurality of grooves 33 shown in FIG. 13, the groove forming member 39 has an integral ring shape along the circumferential direction on the inner peripheral side of the casing 20. There is. Each groove 33 is formed at a predetermined position on the inner peripheral side of the groove forming member 39. Incidentally, although not shown, the groove forming member 39 is disposed on the inner peripheral side of the ring member 20d in the same manner as the groove forming member 38 shown in FIG. Further, the groove forming member 39 is formed in an L shape in a cross sectional view so as to prevent the ring member 20d from coming off.

  The centrifugal pump 100 having the grooves 33 in the groove forming members 38 and 39 includes, for example, solid matter such as sand in the fluid to be pumped, and the grooves form when the grooves 33 are worn by the solid matter. Replacement of the members 38, 39 is possible.

DESCRIPTION OF SYMBOLS 10 impeller 11 main plate 11a level difference part 12 blade | wing 13 side plate 14 pressure-rising flow path 15 suction port 16 discharge port (fluid discharge port)
17 main shaft 20 inner casing (casing)
20a first facing surface 20b second facing surface 21 supply passage 22 main flow passage 24 volute 30 first side chamber (side chamber)
31 second side chamber 33 groove portion 33a end portion 38 groove portion forming member 40 groove portion forming member 40 communication passage 41 diffuser flow passage 42 return flow passage 43 guide blade 43a inner tip 50 water return blade 100 centrifugal pump S1 first gap S2 second gap S3 Third gap

Claims (4)

An impeller having a fluid pressure rising channel between the main plate and the side plate;
A casing for housing the impeller inside;
A main flow path of the fluid formed in the casing so that the fluid discharge port of the pressure increase flow path faces the outer peripheral side of the impeller;
A centrifugal pump having
A side chamber formed between a plate surface of the side plate and a first opposing surface of the casing facing the plate surface;
A gap formed between the outer peripheral end face of the side plate and the second opposing surface of the casing facing to surround the entire outer peripheral end face, and allowing the side chamber to communicate with the main flow path,
Equipped with
It said second facing surface of the casing that forms the gap, the groove so as to extend between said main channel and said side chamber is formed,
The groove portions are formed at equal intervals along the circumferential direction of the second facing surface,
A centrifugal pump comprising: a diffuser having a plurality of guide vanes on the radially outer side of the impeller; and the groove portion is formed to be close to a radially inner end of the guide vanes . An impeller having a fluid pressure rising channel between the main plate and the side plate;
A casing for housing the impeller inside;
A main flow path of the fluid formed in the casing so that the fluid discharge port of the pressure increase flow path faces the outer peripheral side of the impeller;
A centrifugal pump having
A side chamber formed between a plate surface of the side plate and a first opposing surface of the casing facing the plate surface;
A gap formed between the outer peripheral end face of the side plate and the second opposing surface of the casing facing to surround the entire outer peripheral end face, and allowing the side chamber to communicate with the main flow path,
Equipped with
A groove is formed in the second opposing surface of the casing forming the gap so as to extend between the side chamber and the main flow path,
The said groove part is formed so that it may incline with respect to the rotation direction of the said impeller by planar view seen from radial direction outer side to radial direction inner side . The centrifugal pump according to claim 1 or 2 ,
A centrifugal pump characterized in that a cross-sectional shape of the groove portion is a polygonal shape or an arc shape. The centrifugal pump according to claim 1 or 2 ,
A centrifugal pump characterized in that the groove portion is formed by inserting a groove portion forming member separate from the casing into the casing.

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