TW201502380A - Centrifugal pump - Google Patents

Abstract

The centrifugal pump of the present invention can achieve at least one of the following goals: a centrifugal pump that can function more stably, a centrifugal pump that can suppress power degradation, and suppress the amount of dissolvable gas within fluid. The centrifugal pump 1 of the present invention comprises of an inlet 13 for withdrawing fluids; an impeller 5 having a plurality of blades 51 which is provided at the side of the inlet 13 and rotates around a specific axis 3 that passes through the inlet 13. such that the fluid which is withdrawn into the inlet 13 is ejected out along a direction perpendicular to the axis 3; a pump head 6 which is equipped with the inlet 13 and received with the impeller 5; a first opening 10 which opens toward the pump head 6 opposite to the plurality of blades 51 at the side of the inlet 13; a second opening 11 which is arranged in a direction perpendicular to the axis 3 and opens toward at least one pump head 6 in a direction opposite to the side of the inlet 13; and a pathway 12 which connects the first opening 10 with the second opening 11.

Description

Centrifugal pump

The present invention relates to a centrifugal pump.

Usually, a centrifugal pump is used to circulate a liquid such as a coolant required for cooling of a working machine. The centrifugal pump sucks liquid by the differential pressure inside the pump chamber and the outside due to the rotation of the impeller, and is ejected by imparting centrifugal force generated by the rotation of the impeller to the liquid. That is, the centrifugal pump system can realize the suction and discharge of the liquid by the rotation of the impeller and the centrifugal force generated by the rotation.

However, in the centrifugal pump, if the gas is mixed into the liquid, the internal liquid moves to the outside of the impeller, and the centrifugal separation of the gas staying in the center portion of the impeller is generated. Therefore, if the centrifugal pump is continuously mixed with the gas, the gas remaining in the center portion grows with the passage of the operation time due to the influence of the centrifugal separation, and the grown gas closes the suction port and the vicinity of the center portion of the impeller. The reason for the decline in the ability to become a pump.

As a method for solving this problem, there is known a case where a through hole is formed in a center portion of the movable impeller, and gas is retained on the back side of the movable impeller, and is discharged by a vacuum device. Further, the in-tank type vertical centrifugal pump is a two-stage impeller structure in which a moving impeller for pressurizing a pump suction port is provided, and a method is known in which a gas retaining portion is set to a positive pressure, thereby a pump The outdoor part emits gas. However, such methods are a necessity to add new devices or parts, resulting in an increase in cost.

On the other hand, in the work machine industry, in recent years, for the purpose of environmental considerations and cost reduction, there is a tendency to reduce the amount of use of the coolant, and a centrifugal pump is provided. The capacity of the box tends to become smaller. Therefore, in the tank, the number of cycles of the coolant increases, and the gas generated in the circulation of the coolant increases, so that the gas sucked into the centrifugal pump increases. As a result, a large amount of air bubbles are trapped inside the centrifugal pump, and as described above, it is further important to discharge the gas remaining in the center portion of the movable impeller to the outside of the pump chamber.

Environmental considerations and cost reductions are not limited to the working machinery industry, but are common to any industry, especially for working machines that require coolant cooling and need to suppress pumps caused by gas retention inside the pump. The ability to decline.

As a method for solving this problem, Patent Document 1 describes an inner region including a movable impeller, a pump chamber formed by a suction sleeve covering the periphery of the impeller, and a passage from the inner region to the suction port side. The centrifugal separation pump of the suction sleeve of the external exhaust pipe. According to the centrifugal separation pump, it is described that the gas in the gas and liquid sucked from the suction port can be discharged to the outside from the inner region by the exhaust pipe provided in the suction sleeve.

[Advanced technical literature] [Patent Literature]

[Patent Document 1] German Patent Application Publication No. 4325549

According to the centrifugal separation pump described in Patent Document 1, the gas can be discharged to the outside from the internal region of the pump without causing an increase in cost, thereby suppressing a decrease in pump capacity. However, the discharge port of the discharge pipe is only on the suction port side, so that a large amount of discharged gas is caught by the suction of the pump and flows into the inner region again. As a result, the pump gas stays in the internal region, so the frequency of occurrence of suction failure increases. That is, there are many cases where the pump system cannot stably perform its function. In recent years, the working machinery industry has been hoping for a centrifugal pump with reduced capacity, but it is more strongly expected to have a more stable centrifugal pump. Further, there is a case where it is necessary to suppress the amount of a gas (for example, oxygen or the like) dissolved in the liquid according to the type of the liquid to be treated by the centrifugal pump.

Accordingly, it is an object of the present invention to achieve at least one of the following aspects: providing a centrifugal pump that more stably functions, preferably a centrifugal pump that suppresses a decrease in pump capacity; and suppressing a gas dissolved in a liquid the amount.

In order to achieve the object of solving the above problems, a centrifugal pump according to the present invention includes: a suction port that sucks a fluid; and an impeller having a plurality of blades at least on the suction port side and rotating around a specific axis passing through the suction port Thereby, the fluid is sucked from the suction port to discharge the fluid in a direction orthogonal to the shaft; the pump head has a suction port and houses the movable impeller; and the first opening portion faces the plurality of blades on the suction port side. a portion of the pump head that is open; a second opening that opens at a portion of the pump head that is present in a direction orthogonal to the axis and a direction opposite to the suction port; and a passage that opens the first opening Connected to the second opening.

The centrifugal pump of the present invention comprises: a suction port that sucks a fluid; and a moving impeller having a plurality of blades at least on the suction port side and rotating around a specific axis passing through the suction port, thereby sucking the fluid from the suction port And discharging the fluid in a direction orthogonal to the axis; the pump head has a suction port and houses the movable impeller; and the first opening is opened at a portion of the pump head opposite to the plurality of blades on the suction port side; The opening is opened at a portion of the pump head that is present in a direction orthogonal to the axis, and the passage is connected to the first opening and the second opening.

Preferably, the number of passages is two or more and ten or less.

Preferably, when the diameter of the circle connecting the end portions on the inner diameter side of the blade of the impeller is Ds and the diameter of the impeller is D, the first opening is centered on the axis at 1.0. ‧Ds open above 1.0‧D.

Preferably, the cross section of the passage orthogonal to the direction in which the passage extends is circular, and the diameter of the cross section is 10% or more and 50% or less with respect to the diameter of the discharge port of the discharge fluid.

The centrifugal pump of the present invention can realize at least one of the following situations: more stably exerting ability, preferably suppressing a decrease in the capacity of the pump; and suppressing the gas dissolved in the liquid. the amount.

1, 1A‧‧‧ centrifugal pump

2‧‧‧Electric motor

2a‧‧‧Flange

3‧‧‧Axis

3a‧‧‧through hole

3b‧‧‧ Body Department

3c‧‧‧End

3d‧‧‧screws

3e‧‧‧ lock key

4‧‧‧ Protective cover

5‧‧‧moving impeller

6, 6A, 6B, 6C, 6D, 6E‧‧ ‧ pump head

6F‧‧‧ pump head

7‧‧‧ end face

7a‧‧‧1st end

7b‧‧‧2nd end

8‧‧‧ side

8a‧‧‧1st side

8b‧‧‧2nd side

9‧‧‧ pump room

9a‧‧‧Area

10, 10a‧‧‧ first opening

11, 11b‧‧‧ second opening

11c‧‧‧2nd opening

12‧‧‧ pathway

Vents 12a, 12b, 12c, 12d, 12e, 12f, 12g, 12h, 12i‧‧

13‧‧‧Inhalation

14‧‧‧Spray outlet

14b‧‧‧ Groove

15‧‧‧Support components

16, 16a‧‧‧L type piping

17, 17a‧‧‧ piping

18‧‧‧Connecting components

19a, 19b‧‧‧ screw

20a, 20b‧‧‧ nuts

21‧‧‧ moving impeller nut

22‧‧‧through holes

24‧‧‧Sink box

25‧‧‧ Fluid

26‧‧‧Pipe (for recycling)

27‧‧‧ pressure gauge

28‧‧‧Valves

29‧‧‧Export

30‧‧‧ Plug

31‧‧‧ screw section

50‧‧‧ disc

50a‧‧‧ Central Department

50b‧‧‧Lock keyway

50c‧‧‧through hole

50d‧‧‧ outer edge

51‧‧‧ blades

52‧‧‧Seat

53‧‧‧Circle

60, 600‧‧‧ shell

60a, 60b, 61b‧‧‧ inside

60c‧‧‧ inside

60d‧‧‧ inside

60e‧‧ plane

61, 610‧‧ ‧ suction hood

61a‧‧‧ Plane

61c‧‧‧ surface

61d‧‧‧ plane

62‧‧‧ recess

62a‧‧‧ recess

63‧‧‧ convex

64‧‧‧Face Parts

65A‧‧‧ parts

65B‧‧‧ parts

65C‧‧‧ parts

65D‧‧‧ parts

65E‧‧‧ parts

70‧‧‧2nd exit

C1, C2, C3, C4, C5‧‧‧ Center

CL‧‧‧ center line

CL1‧‧‧ center line

CP‧‧‧ central area

Dp‧‧‧depth

D1‧‧‧diameter

D, D1, D2, D3, D4‧‧‧ diameter

Db‧‧‧ box diameter

Ds‧‧‧ diameter

H, Hb, h1, h2, h3, h4, h5‧‧‧ height

L1, L2, L3, L4, L5, L6, L7‧‧‧ length

LH‧‧‧ length

LW‧‧‧ length

P1, P2‧‧‧ dotted line

R‧‧‧ distance

R1‧‧‧ distance

S‧‧‧Scope

Α1, α2‧‧‧ angle

Fig. 1 is an external view showing a partial cross section of a centrifugal pump according to an embodiment of the present invention.

Fig. 2 is a plan view showing a movable impeller shown on the suction side of the embodiment of the present invention.

Fig. 3 is a schematic cross-sectional view showing a pump head according to an embodiment of the present invention.

Fig. 4 is a plan view of a suction cover according to an embodiment of the present invention.

Fig. 5 is a plan view showing the region of the convex portion of the region of the diameter of the movable impeller of the embodiment of the present invention.

Fig. 6 is a schematic cross-sectional view showing a first modification of the pump head according to the embodiment of the present invention.

Fig. 7 is a schematic cross-sectional view showing a second modification of the pump head according to the embodiment of the present invention.

Fig. 8 is a schematic cross-sectional view showing a third modification of the pump head according to the embodiment of the present invention.

Fig. 9 is a schematic cross-sectional view showing a fourth modification of the pump head according to the embodiment of the present invention.

Fig. 10 is a perspective view showing a test apparatus of a centrifugal pump according to an embodiment of the present invention.

Fig. 11 is a graph showing the results of a first performance test of the centrifugal pump according to the embodiment of the present invention.

Fig. 12 is a schematic cross-sectional view showing a pump head applied to a second performance test of the centrifugal pump according to the embodiment of the present invention.

Fig. 13 is a graph showing the results of a second performance test of the centrifugal pump according to the embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail based on the drawings. Furthermore, the present invention is not limited to the embodiment.

Fig. 1 is an external view showing a partial cross section of a centrifugal pump according to an embodiment of the present invention. Fig. 2 is a plan view showing a movable impeller according to an embodiment of the present invention. Fig. 3 is a schematic cross-sectional view showing a pump head according to an embodiment of the present invention. Fig. 4 is a plan view of a suction cover according to an embodiment of the present invention. Fig. 5 is a plan view showing the region of the convex portion of the region of the diameter of the movable impeller of the embodiment of the present invention. In the present embodiment, the motor of the centrifugal pump 1 is described as an example of the motor, but the prime mover of the centrifugal pump is not limited thereto. For example, a centrifugal pump can also be used as a prime mover.

The centrifugal pump 1 includes a motor 2, a shaft 3 connected to the motor 2, a movable impeller 5 connected to the end portion 3c of the shaft 3, and a pump head 6 accommodating the movable impeller 5. Further, the centrifugal pump 1 includes a protective cover 4 that is disposed on the outer circumference of the shaft 3 to protect the shaft 3, and a support member 15 that is coupled to the protective cover 4 and the motor 2 to support the motor 2. Further, the protective cover 4 is coupled to the support member 15 and the pump head 6. The pump head 6 has a casing 60 and a suction cover 61, and is formed with a suction port 13 for sucking a fluid and a discharge port 14 for discharging a fluid. Further, the outer casing 60 and the suction cover 61 are fixed by a screw 19b and a nut 20b. The pump head 6 is formed with a first opening 10 at a portion 65A of the suction cover 61. Further, the pump head 6 is formed with a second opening portion 11 at a portion 65B of the suction cover 61. A passage 12 that connects the first opening 10 and the second opening 11 is formed in the suction cover 61 of the pump head 6. An L-shaped pipe 16 is connected to the discharge port 14 toward the drive side of the pump. Further, a pipe 17 and a connecting member 18 are connected to the L-shaped pipe 16.

The centrifugal pump 1 rotates the shaft 3 by driving electric motor 2 from the outside, and the moving impeller 5 fixed to the end portion 3c of the shaft 3 is centered on the center line CL of the specific shaft passing through the suction port 13. Rotation is performed to thereby suck the fluid and eject it in a direction orthogonal to the center line CL.

The motor 2 is a prime mover (drive source) that rotates the shaft 3. The motor 2 is provided with a flange 2a on the support member 15 (on the side of the suction port 13 of the centrifugal pump 1). The flange 2a is provided by the screw 19a and The nut 20a is fixed to the support member 15.

The shaft 3 includes a body portion 3b of a metal round rod extending from the motor 2 toward the pump head 6 side, and an end portion 3c fixed to one end of the body portion 3b. The body portion 3b is connected to the motor 2 and is protected by a protective cover 4. A lock key 3e is attached to the end portion 3c, and a screw portion 3d is formed in front of the end portion 3c. The protective cover 4 is fixed to the support member 15 by, for example, welding, and supports the support member 15.

The moving impeller 5 has a plurality of blades and has a diameter D. Specifically, as shown in FIG. 2, the movable impeller 5 has a disk 50 and a plurality of blades 51. The movable impeller 5 is integrally formed with six blades 51 by a disc 50 made of a resin having a diameter D. Further, although not shown, six blades are integrally formed in the same manner on the back side of the disk 50. A boss portion 52 is formed in the center portion 50a of the disk 50. The boss portion 52 is formed with a through hole 50c including a lock groove 50b. As shown in Fig. 1, the movable impeller 5 is fitted to the lock key groove 50b to screw the movable impeller nut 21 to the screw portion 3d of the shaft 3, thereby being fixed to the end portion 3c of the shaft 3.

The movable impeller 5 is formed in a central region CP between the boss portion 52 and the circumference 53 of the end portion on the inner diameter side of the blade 51 that connects the movable impeller 5 with a diameter Ds. The movable impeller 5 is provided with six blades 51 on the outer side in the diameter direction of the center region CP. The blades 51 are formed so as to be curved from the circumference 53 toward the outer edge 50d of the disk 50 in the reverse rotation direction of the movable impeller 5, and are disposed at equal intervals toward the circumferential direction of the disk 50. Further, the disk 50 is not limited to a resin, and may be made of a metal such as stainless steel. Here, the movable impeller 5 may not integrally form the disk 50 and the blade 51. For example, the impeller 5 can also be mounted on the disc 50 to form the blade 51.

As shown in FIG. 3, the pump head 6 has a cylindrical shape, and has a through hole 3a and a suction port 13 centered on the center line CL, and accommodates the movable impeller 5. The pump head 6 has a cylindrical outer casing 60, a flange-shaped suction cover 61, and a screw 19b and a nut 20b that fix the outer casing 60 and the suction cover 61.

The outer casing 60 is formed so that the first end surface 7a of the end surface of the pump head 6 in the central axis CL direction (the surface which becomes the end in the central axis CL direction) 7 is perpendicular to the center line CL. In the outer casing 60, a through hole 3a centering on the center line CL is formed from the first end surface 7a toward the concave portion 62a. Insert shaft 3 into Through hole 3a.

The outer casing 60 is formed with a through hole 3a centering on the center line CL, a recess 62, and a recess 62a. The concave portion 62 is formed on the surface of the suction cover 61 side (the surface on the suction port 13 side), and is formed to be convex toward the through hole 3a side. The recess 62 includes an inner surface 60d that intersects the plane 61d and is parallel to the center line CL, and an inner surface 60c that is perpendicular to the center line CL. The depth of the concave portion 62 from the surface on the suction cover 61 side (the surface on the suction port 13 side) to the inner surface 60c is dp. The recessed portion 62 is formed on the side of the through hole 3a of the recessed portion 62, that is, the inner surface 60c. The recess 62a includes an inner surface 60b that is parallel to the center line CL, and an inner surface 60a that is perpendicular to the center line CL. The concave portion 62a is formed in a cross section passing through the central axis CL, and the distance between the inner faces 60b becomes shorter than the distance between the inner faces 60a.

A first side surface 8a which is a side surface of the pump head 6 (an end surface orthogonal to the central axis CL of the pump head 6) 8 is formed in the outer casing 60. The casing 60 is formed with a discharge port 14 that is opened from the first side face 8a and that is open to the inner face 60b of the recess 62a. The diameter of the end portion of the discharge port 14 on the inner surface 60a side is D3. That is, the diameter of the opening at the position where the discharge port 14 communicates with the space inside the recess 62a is D3. The outer casing 60 is formed with a recessed portion 14b formed in the discharge port 14, and the recessed portion 14b is recessed from the first side surface 8a toward the recessed portion 62, and is connected to the pipe. Further, the groove portion 14b is provided to facilitate insertion of the pipe, but is not limited thereto. For example, the groove portion 14b may not be provided as long as the pipe can be connected to the discharge port 14.

As shown in FIG. 3, the suction cover 61 is formed with a flat surface 60e perpendicular to the center line CL, and a curved surface portion 64 including a second side surface 8b and a second end surface 7b which are parallel to the center line. CL becomes the side surface 8 of the pump head 6, and the second end surface 7b is perpendicular to the center line CL and becomes the end surface 7 of the pump head 6. Further, the suction cover 61 is provided with a convex portion 63 having a height H which is formed by a curved surface 61c parallel to the center line CL and a plane 61a perpendicular to the center line CL, and protrudes from the curved surface portion 64 toward the outer casing 61. The suction cover 61 is formed with a through hole that serves as a suction port 13 that penetrates from the second end surface 7b toward the flat surface 61a and is centered on the center line CL.

The pump head 6 is attached to the suction port 13 side of the suction cover 61 and is connected to the plurality of blades of the movable impeller 5 The 51 facing portion 65A has a first opening 10 in the opening. The first opening 10 is formed on the side of the suction port 13 of the suction cover 61 and opens to a plane 61a opposite to the plurality of blades 51 of the movable impeller 5 having a diameter D.

Further, the pump head 6 is formed in a portion 65B that is present in a direction orthogonal to the center line CL, and has a second opening portion 11 opened. Specifically, the second opening portion 11 is opened in the direction orthogonal to the center line CL and on the second side surface 8b. That is, in the present embodiment, the second side face 8b corresponds to the portion 65B of the pump head 6 that exists in the direction orthogonal to the center line CL. The center C1 of the first opening portion 10 is formed on the circumference of the diameter D1 centering on the center line CL. Further, the first opening 10 is opened in the vicinity of the central region CP of the movable impeller 5. The second opening 11 is opened in a direction orthogonal to the center line CL. The center C2 of the second opening portion 11 is formed at a position R from the second end surface 7b. Further, a screw portion 31 is formed in the second opening portion 11.

A vent hole 12a and a vent hole 12b are formed in the suction cover 61. The cross section of the vent hole 12a and the vent hole 12b orthogonal to the extending direction is circular. The suction cover 61 is in communication with the exhaust hole 12b and communicates with the exhaust hole 12b to form the passage 12. The vent hole 12a is a hole having a length L1 and a diameter d1 extending from the first opening portion 10 toward the second end surface 7b. The vent hole 12b is a hole having a length L2 and a diameter d1 extending from the second opening portion 11 toward the suction port 13. An end portion of the exhaust hole 12a opposite to the first opening portion 10 and an end portion of the exhaust hole 12b opposite to the second opening portion 11 are connected to the suction cover 61 at an angle α1. Thereby, the exhaust hole 12a and the exhaust hole 12b are in communication passage 12, and the first opening 10 exposed in the recess 62a communicates with the second opening 11 exposed on the side surface 8b. The length L1 of the vent hole 12a is shorter than the length LH from the plane 61a to the second end face 7b, and the length L2 of the vent hole 12b is shorter than the length LW from the second side face 8b to the inner face 61b. Further, in the present embodiment, the diameter d1 of the exhaust hole 12a and the exhaust hole 12b are the same size, but the shape is not limited thereto, and may be different diameters. Further, the angle α1 is connected at 90°, but is not limited thereto, and may be, for example, an acute angle or an obtuse angle.

As shown in FIG. 4, in the suction cover 61, eight through holes 22 and a suction port 13 are formed in order to penetrate the screw 19b. Further, the first opening 10, the second opening 11, the exhaust hole 12a, and Each of the vent holes 12b is four, and is formed at an interval of an angle α2. Here, the angle α2 refers to a central angle based on the center line CL1 and is an angle formed by the adjacent exhaust holes 12b. Further, in the present embodiment, the angle α2 is 90°, but is not limited thereto. For example, the first opening 10, the second opening 11, the exhaust hole 12a, and the exhaust hole 12b may be one to three. Further, the first opening 10, the second opening 11, the exhaust hole 12a, and the exhaust hole 12b may be five or more, and the angle α2 may be formed at 60 or 30 degrees.

As shown in FIG. 3, the pump head 6 is formed by inserting the convex portion 63 of the suction cover 61 into the concave portion 62 of the outer casing 60. Specifically, the concave portion 62 and the convex portion 63 are in contact with the inner surface 60d of the concave portion 62 and the curved surface 61c of the convex portion 63, and the flat surface 61d of the concave portion 62 is in contact with the flat surface 60e of the curved surface portion 64. The height H of the convex portion 63 of the suction cover 61 is formed lower than the depth dp of the concave portion 62 of the outer casing 60. Therefore, when the convex portion 63 of the suction cover 61 is inserted into the concave portion 62 of the outer casing 60 to form the pump head 6, the pump chamber 9 which is the internal space is formed.

The pump chamber 9 is formed by the suction port 13, the region 9a, and the discharge port 14. The region 9a is a space surrounded by the inner surface 60a, the inner surface 60b, the inner surface 60c, the inner surface 60d of the outer casing 60, and the plane 61a of the convex portion 63 of the suction cover. One of the regions 9a to the flat surface 61a is connected to the suction port 13, and a portion of the inner surface 60d is connected to the discharge port 14. That is, the pump chamber 9 is a region from the suction port 13 to the discharge port 14 via the region 9a. As shown in FIG. 1, the flow system discharged from the discharge port 14 is discharged to the outside through the L-shaped pipe 16, the pipe 17 connected to the L-shaped pipe 16, and the connecting member 18 connected via the support member 15. Further, the pump chamber 9 is a combination of the outer casing 60 and the inner portion of the suction cover 61, but is not limited thereto. For example, even if the pump head 6 is one processed product or a molded product, the pump chamber 9 may be formed with a region that serves as a flow path.

The principle of the centrifugal pump 1 is as follows: By rotating the impeller 5, a negative pressure is generated at the inlet portion of the impeller 5, and the fluid is sucked from the suction port 13. Further, the centrifugal pump 1 is required to discharge the gas remaining in the inner region of the pump chamber 9 to the passage 12 which is connected to the pressure side of the pressure lower than the central region CP of the impeller 5 . For example, if the centrifugal pump 1 immersed in the water tank is not present when the pump is used alone, it is generated to be lower than the central portion of the impeller 5 The portion of the pressure generated by the pressure generated by the domain CP is also unable to generate a pressure which is lower than the pressure generated in the central region CP of the impeller 5 . Therefore, in the blade portion 51 of the movable impeller 5, there is a function of pressurization, so that it is close to the central region CP of the movable impeller 5, and the portion 65A of the pump head 6 opposed to the blade 51 of the movable impeller 5 is opened from the pump chamber. 9 leads to the external path 12. Therefore, the gas can be discharged to the outside of the pump chamber 9 by the differential pressure between the central region CP of the impeller 5 and the outside of the pump chamber 9. Further, the second opening portion 11 is provided in the portion 65B of the pump head 6 which is present in the direction orthogonal to the center line CL, whereby the gas system discharged is subdivided by the pressurization of the impeller 5 The bubbles rise to the fluid in the sink. Moreover, it is possible to suppress the bubble from entering again from the suction port 13. In other words, when the gas remaining in the central region CP is discharged as a bubble only to the suction port 13 side, a large number of air bubbles are sucked from the suction port 13. Moreover, the bubble that is inhaled is discharged again into the water tank. That is, the bubbles circulate in the water tank and in the pump. In the present embodiment, a large number of bubbles are discharged in a direction orthogonal to the center line CL and rise in the water tank. Therefore, the centrifugal pump 1 can suppress the bubble from entering again from the suction port 13. As a result, the amount of gas remaining in the central region CP is reduced, so that the centrifugal pump 1 can suppress the occurrence of suction failure and discharge failure and stably exhibit the ability. Further, since the centrifugal pump 1 has a small amount of gas remaining in the central region CP, it is possible to suppress a decrease in the ability.

If the bubble is in contact with the liquid, there is a case where a gas forming a bubble is dissolved in the liquid. In this case, the longer the bubble stays in the liquid, the more the amount of gas dissolved in the liquid. In the present embodiment, the distance in which the bubble is discharged in the direction orthogonal to the center line CL and floats up to the water surface in the water tank is shorter than the distance which is discharged from the suction port 13 side and floats up to the water surface in the water tank. Therefore, the time during which the bubble stays in the liquid becomes shorter than the case where it is discharged only from the side of the suction port 13. As a result, the centrifugal pump 1 can suppress the amount of gas dissolved in the liquid.

The number of the passages 12 is preferably two or more and ten or less. Here, the number of the passages 12 refers to the number of paths through which the bubbles are discharged. When the number of the passages 12 is two or more, it is possible to discharge the bubbles in a well-balanced manner as long as they are equally distributed with respect to the center line CL. another On the other hand, by setting the number of the passages 12 to 10 or less, it is possible to realize efficient exhaust gas without discharging the liquid which is a reduced amount of the pump. More preferably, the passage 12 is four or more and eight or less.

When the diameter of the start end of the blade 51 of the movable impeller 5 (the circle connecting the end of the center line CL side) is Ds and the diameter of the movable impeller 5 is D, the first opening portion 10 is preferably The center line CL is centered and opens in a range S of 1.0‧Ds or more and 1.0‧D or less. In other words, the first opening portion 10 is preferably formed in a range S surrounded by a circle having a diameter of 1.0‧Ds centered on the center line CL and a circle of 1.0‧D centered on the center line CL. Here, as shown in FIG. 5, the range S is shown in the suction cover 61, and is surrounded by a broken line P2 indicating 1.0‧Ds and a broken line P1 indicating 1.0‧D, and includes broken lines P1 and P2.

The centrifugal pump 1 can be opened by the first impeller 5 by the opening of the first impeller 10 on the outer side (including the boundary) having a diameter of 1.0‧Ds centered on the center line CL. The opening 10 discharges the gas of the central area CP. On the other hand, the centrifugal pump 1 can suppress the pressurization of the impeller 5 by opening the first opening 10 on the inner side (including the boundary) of the circle having a diameter of 1.0‧D centered on the center line CL. The caused liquid flows out from the first opening portion 10, thereby suppressing a decrease in the capacity of the pump.

Further, the first opening portion 10 is preferably opened on the outer side of a circle having a diameter of 1.05‧Ds centered on the center line CL and a circle having a diameter of 1.0‧Ds+7 mm. Here, 1.0‧Ds+7mm means that the length LW and the length L2 shown in Fig. 3 are considered in addition to the diameter Ds of the start end of the blade 51 of the impeller 5 (the circle connecting the end of the center line CL side). The difference is the minimum wall thickness and the value of the smallest diameter of the passage 12. Further, it is preferable that the minimum wall thickness is 1 mm (2 mm in diameter), and the minimum diameter of the passage is 5 mm. The first opening 10 is formed on the outer side of a circle having a diameter of 1.05 ‧ Ds or a circle having a diameter of 1.0 ‧ Ds + 7 mm, so that the minimum thickness can be ensured, and the processing of the first opening 10 is facilitated. On the other hand, the first opening portion 10 is more preferably an inner opening of a circle having a diameter of (D-Ds) / 2 + Ds. Here, the circle having a diameter of (D-Ds) / 2 + Ds means a circle passing through the center of the range S. If the first opening portion 10 is inside the circle having a diameter of (D-Ds) / 2 + Ds, The discharge of the bubbles by the pressurization of the impeller 5 becomes advantageous.

The diameter d1 of the passage 12 is preferably 10% or more and 50% or less with respect to the diameter D3 of the discharge port 14. By setting the diameter d1 to 10% or more with respect to the diameter D3 of the discharge port 14, it is possible to discharge bubbles which are substantially equal to the gas continuously sucked. On the other hand, by setting the diameter d1 to 50% or less with respect to the diameter D3 of the discharge port 14, the discharge of the liquid to the discharge port 14 can be suppressed. Further, specifically, the diameter d1 is preferably 5 mm or more and 20 mm or less. Further, it is preferably 8 mm or more and 12 mm or less.

Fig. 6 is a schematic cross-sectional view showing a first modification of the pump head according to the embodiment of the present invention. The first modification is the same as the above-described embodiment, but differs in that the second opening portion 11 is opened in the portion 65B of the pump head 6A, and the second discharge port 70 is also opened in the portion 65C of the pump head 6A. In the description of the first modification, the description of the configuration similar to the above-described embodiment will be omitted in principle, and the description will be focused on the different configurations.

The pump head 6A is provided on the suction port 13 side of the suction cover 61, and has a first opening portion 10 at a portion 65A opposite to the plurality of blades 51 of the movable impeller 5. The first opening portion 10 is provided on the suction port 13 side of the suction cover 61, and is open to the plane 61a opposite to the plurality of blades 51 of the movable impeller 5.

Further, the pump head 6A is formed in a portion 65B that is present in a direction orthogonal to the center line CL, and has a second opening portion 11 opened. Specifically, the second opening portion 11 is opened in the direction orthogonal to the center line CL and on the second side surface 8b. Further, the pump head 6A is attached to the portion 65C of the suction cover 61, and the second discharge port 70 is opened. That is, in the present modification, the second side face 8b corresponds to the portion 65B of the pump head 6A existing in the direction orthogonal to the center line CL. Further, the second end face 7b corresponds to the portion 65C of the pump head 6A.

The center C1 of the first opening portion 10 is formed on the circumference of the diameter D1 centering on the center line CL. Further, the first opening 10 is opened in the vicinity of the central region CP of the movable impeller 5. The second opening 11 is opened in a direction orthogonal to the center line CL. The center C2 of the second opening portion 11 is formed at a position R from the second end surface 7b. Further, the second discharge port 70 is opened on a circumference concentric with the first opening portion 10 and having a diameter D1. Also, in the second opening The mouth portion 11 and the second discharge port 70 are formed with a screw portion 31.

The suction cover 61 is formed with a vent hole 12c and a vent hole 12b. The cross section of the vent holes 12c and 12b orthogonal to the direction in which they extend is circular. The suction cover 61 is connected to the exhaust hole 12c through the exhaust hole 12b to form the passage 12. The vent hole 12c is a hole having a length LH and a diameter d1 extending from the first opening portion 10 toward the second end surface 7b. Further, the exhaust hole 12c penetrates from the first opening portion 10 to the second end surface 7b. The vent hole 12b is a hole having a length L2 and a diameter d1 extending from the second opening portion 11 toward the suction port 13. Further, the width of the end portion of the exhaust hole 12b opposite to the second opening portion 11 and the width of the exhaust hole 12c are in the suction cover 61, and are connected at an angle α1. Thereby, the passage 12 in which the exhaust hole 12b and the exhaust hole 12c communicate with each other is exposed to the first opening 10 of the recess 62a, the second discharge port 70 exposed to the second end surface 7b, and the second side surface 8b. The second opening 11 is in communication. The length L2 of the vent hole 12b is shorter than the length LW from the second side face 8b to the inner face 61b. Further, in the present embodiment, the diameter d1 of the exhaust hole 12b and the exhaust hole 12c are the same size, but the shape is not limited thereto, and may be different diameters. Further, the angle α1 is connected at 90°, but is not limited thereto, and may be, for example, an acute angle or an obtuse angle.

In the first modification of the present invention, the pump head 6A is formed with the passage 12 that communicates the second opening 11 and the second discharge port 70 from the first opening 10, whereby the centrifugal pump 1 is exhausted from the pump chamber 9 The holes 12b and 12c discharge the gas remaining in the central region CP of the movable impeller 5 to the outside of the pump head 6A. The centrifugal pump 1 of the first modification is also formed with a discharge port on the suction port 13 side of the portion 65C of the pump head 6A. Further, the bubble is discharged from the direction orthogonal to the center line CL and the suction port side. Therefore, when the bubble is discharged only to the suction port side, the first variation may be such that the bubble is discharged from the direction orthogonal to the center line CL, so that the amount of the bubble floating in the water tank increases. Further, in the first modification, the amount of air bubbles sucked from the suction port can be suppressed. As a result, the centrifugal pump 1 according to the first modification can suppress the occurrence of suction failure and discharge failure and stably exhibit the ability. Further, in the first variation, the amount of gas remaining in the central region CP is small, so that the ability of the pump can be suppressed from being lowered.

In addition, when the air bubbles are discharged from the suction port side, the air bubbles are discharged from the second opening portion 11 and the second discharge port 70, so that the amount of air bubbles rising to the water surface in the water tank is increased. As a result, in the first variation, the amount of the gas dissolved in the liquid can be suppressed as compared with the case where the bubble is discharged only from the suction port side.

Fig. 7 is a schematic cross-sectional view showing a second modification of the pump head according to the embodiment of the present invention. The second modification is the same as the embodiment shown in FIG. 3, but differs in that the second opening 11b is opened in the portion 65D of the pump head 6B. In the description of the second modification, the description of the configuration shown in FIG. 3 will be omitted in principle, and the description will be focused on the different configurations.

The pump head 6B is attached to the suction port 13 side of the suction cover 61, and has a first opening 10 opened to a portion 65A opposite to the plurality of blades 51 of the movable impeller 5. The first opening portion 10 is provided on the suction port 13 side of the suction cover 61, and is open to the plane 61a opposite to the plurality of blades 51 of the movable impeller 5.

Further, the pump head 6B is formed in a portion 65B that is present in a direction orthogonal to the center line CL, and has a second opening portion 11 opened. Specifically, the second opening portion 11 is opened in the direction orthogonal to the center line CL and on the second side surface 8b. Further, the pump head 6B is attached to the portion 65D of the outer casing 60, and the second opening portion 11b is opened. That is, in the present modification, the second side face 8b corresponds to the portion 65B of the pump head 6B which is present in the direction orthogonal to the center line CL. Further, the first end face 7a corresponds to the portion 65D of the pump head 6B.

The center C1 of the first opening portion 10 is formed on the circumference of the diameter D1 centering on the center line CL. Further, the first opening 10 is opened in the vicinity of the central region CP of the movable impeller 5. The second opening 11 is opened in a direction orthogonal to the center line CL, and the center C2 of the second opening 11 is formed at a position R from the second end surface 7b. Further, the center C3 of the second opening portion 11b is formed on the circumference of the diameter D2 centering on the center line CL. Further, a screw portion 31 is formed in the second opening portion 11 and the second opening portion 11b.

The suction cover 61 is formed with an exhaust hole 12a, an exhaust hole 12b, an exhaust hole 12d, and an exhaust hole 12e. The vent hole 12a, the vent hole 12b, the vent hole 12d, and the vent hole 12e extend and extend The cross section of the direction is circular. The suction cover 61 is a passage 12 through which the exhaust hole 12a, the exhaust hole 12b, the exhaust hole 12d, and the exhaust hole 12e communicate. The vent hole 12a is a hole having a length L1 and a diameter d1 extending from the first opening portion 10 toward the second end surface 7b. The vent hole 12b is a hole having a length L2 and a diameter d1 extending from the second opening portion 11 toward the suction port 13. The vent hole 12d is a hole having a length L3 and a diameter d1 extending from the second opening portion 11b toward the flat surface 61d. Further, the exhaust hole 12d penetrates from the second opening portion 11b to the flat surface 61d. The vent hole 12e is a hole having a length L4 and a diameter d1 extending from the plane 60e toward the second end surface 7b. An end portion of the vent hole 12a opposite to the first opening portion 10 and an end portion of the vent hole 12b opposite to the second opening portion 11 are attached to the suction cover 61, and are connected at an angle α1. Further, an end portion of the exhaust hole 12d opposite to the second opening portion 11b is connected to an end portion of the exhaust hole 12e opposite to the second end surface 7b. Further, the second end face 7b side of the exhaust hole 12e is connected to the suction cover 61, and is connected to the exhaust hole 12b at an angle α1. Thereby, the exhaust hole 12a, the exhaust hole 12b, the exhaust hole 12d, and the exhaust hole 12e serve as the passage 12 that communicates. Further, the first opening 10 exposed in the concave portion 62a, the second opening 11b exposed to the first end surface 7a, and the second opening 11 exposed to the second side surface 8b communicate with each other. Further, in the present embodiment, the diameter d1 of the exhaust hole 12a, the exhaust hole 12b, the exhaust hole 12d, and the exhaust hole 12e are the same size, but the shape is not limited thereto, and may be different diameters from each other. . Further, the angle α1 is connected at 90°, but is not limited thereto, and may be, for example, an acute angle or an obtuse angle.

In the second modification of the present invention, the first opening 10, the second opening 11, the second opening 11b, the exhaust hole 12a, the exhaust hole 12b, the exhaust hole 12d, and the exhaust are formed in the pump head 6B. The hole 12e, whereby the centrifugal pump 1 can be discharged from the pump chamber 9 to the center of the movable impeller 5 via the exhaust hole 12a, the exhaust hole 12b, the exhaust hole 12d, and the exhaust hole 12e to the outside of the pump head 6B. CP gas. The pump-based second opening portion 11b of the second modification is formed on the opposite side of the suction port of the portion 65D of the pump head 6B. Further, the bubble is discharged in a direction orthogonal to the center line CL and in a direction opposite to the suction port. Therefore, in comparison with the case where the air bubbles are discharged only toward the suction port side, the second modification can more preferably suppress the amount of air bubbles sucked into the centrifugal pump 1 again. As a result, the pump including the second modification can suppress the occurrence of suction failure and discharge failure, and can more stably exhibit the ability. Further, in the first modification, since the amount of gas remaining in the central region CP is small, the ability of the pump can be suppressed from being lowered.

Further, in the second variation, the distance from which the air bubbles are discharged from the second opening portion 11b and floated to the water surface is shorter than the distance at which the air bubbles are discharged from the suction port side and rise to the water surface. Further, the distance from which the air bubbles are discharged from the second opening portion 11b and floated to the water surface is shorter than the distance at which the air bubbles are discharged from the second opening portion 11 and rise to the water surface. Therefore, the centrifugal pump 1 of the second modification can shorten the time during which the bubble stays in the liquid, so that the time during which the bubble stays in the liquid is less. Therefore, in the second variation, the amount of the gas dissolved in the liquid can be preferably suppressed as compared with the case where the bubble is discharged only in the direction orthogonal to the center line CL.

Here, the second variation is an example in which bubbles are discharged from a direction orthogonal to the center line CL and in a direction opposite to the suction port side, but a row of bubbles may be formed only in a direction opposite to the suction port side. Export. That is, the second opening portion 11b is formed only in the portion 65D of the pump head 6B.

The second opening portion 11b, which is a discharge port for forming a bubble in the opposite direction to the suction port side, is discharged only from the second opening portion 11b. That is, the bubbles are discharged from a direction closer to the water surface in the water tank. Further, if the air bubbles are compared with the example in which only the direction perpendicular to the center line CL is discharged, the distance from the floating surface to the water surface is also shortened, and the time for staying in the liquid is also shortened. As a result, in the second modification, the amount of the gas dissolved in the liquid can be more preferably suppressed. Further, since the amount of the gas dissolved in the liquid can be more preferably suppressed, it is particularly preferable in the case of treating a liquid in which the gas is dissolved.

Fig. 8 is a schematic cross-sectional view showing a third modification of the pump head according to the embodiment of the present invention. The third modification is the same as the embodiment shown in FIG. 3, but differs in that the second opening 11c is opened in the portion 65E of the pump head 6C. In the description of the third modification, the description of the configuration shown in FIG. 3 will be omitted in principle, and the description will be centered on different configurations.

The pump head 6C is attached to the suction port 13 side of the suction cover 61 and has a first opening 10 opened in a portion 65A opposed to the plurality of blades 51 of the movable impeller 5. Specifically, the first opening portion 10 is formed on the suction port 13 side of the suction cover 61 and is open to the plane 61a opposite to the plurality of blades 51 of the movable impeller 5 .

Further, the pump head 6C is formed in a portion 65E that is present in a direction orthogonal to the center line CL, and has a second opening portion 11c. Specifically, the second opening portion 11c is opened in the first side surface 8a in the direction orthogonal to the center line CL. In the present modification, the first side face 8a corresponds to the portion 65E of the pump head 6C existing in the direction orthogonal to the center line CL.

The center C1 of the first opening portion 10 is formed on the circumference of the diameter D1 centering on the center line CL. Further, the first opening 10 is opened in the vicinity of the central region CP of the movable impeller 5. The second opening 11c is opened in a direction orthogonal to the center line CL, and the center C4 of the second opening 11c is formed at a position R1 from the first end surface 7a. Further, a screw portion 31 is formed in the second opening portion 11c.

A vent hole 12f is formed in the outer casing 60. Further, in the suction cover 61, an exhaust hole 12g and an exhaust hole 12h are formed. The cross section of the exhaust hole 12f, the exhaust hole 12g, and the exhaust hole 12h orthogonal to the extending direction is circular. The outer casing 60 communicates with the suction cover 61 through the exhaust hole 12f, the exhaust hole 12g, and the exhaust hole 12h to form the passage 12. The vent hole 12f is a hole having a length L6 and a diameter d1 extending from the second opening portion 11c toward the inner surface 60d. Further, the exhaust hole 12f penetrates from the second opening portion 11c to the inner surface 60d. The vent hole 12g is a hole having a length L5 and a diameter d1 extending from the first opening portion 10 toward the second end surface 7b. The vent hole 12h is a hole having a length L7 and a diameter d1 extending from the curved surface 61c toward the suction port 13. An end portion of the exhaust hole 12f opposite to the second opening portion 11c is connected to an end portion of the exhaust hole 12h opposite to the suction port 13. An end portion of the vent hole 12g opposite to the first opening portion 10 and an end portion of the vent hole 12h opposite to the curved surface 61c are attached to the suction cover 61 and connected at an angle α1. Thereby, the exhaust hole 12f, the exhaust hole 12g, and the exhaust hole 12h serve as the communication passage 12, and the first opening 10 exposed in the recess 62a communicates with the second opening 11c exposed on the first side surface 8a.

The length L5 of the vent hole 12g is shorter than the length LH from the plane 61a to the second end face 7b, and the length L7 of the vent hole 12h is shorter than the length LW from the second side face 8b to the inner face 61b. Further, the length L5 of the vent hole 12g is shorter than the length L1 of the vent hole 12a shown in FIG. Further, the length of the length L6 of the exhaust hole 12f and the length L7 of the exhaust hole 12h are the same as the length L2 of the exhaust hole 12b shown in Fig. 3 . Further, in the present modification, the diameter d1 of the exhaust hole 12f, the exhaust hole 12g, and the exhaust hole 12h are the same size, but the shape is not limited thereto, and may be different diameters. Further, the angle α1 is connected at 90°, but is not limited thereto, and may be, for example, an acute angle or an obtuse angle.

The first opening 10, the second opening 11c, the exhaust hole 12f, the exhaust hole 12g, and the exhaust hole 12h are formed in the pump head 6C, whereby the centrifugal pump 1 is exhausted from the pump chamber 9 through the exhaust hole 12f and exhausted The hole 12g and the vent hole 12h discharge the gas remaining in the central region CP of the movable impeller 5 to the outside of the pump head 6C. In the third variation, the length L5 of the exhaust hole 12g is shorter than the length L1 of the exhaust hole 12a shown in FIG. Therefore, the distance at which the bubble is discharged becomes short, and the resistance at the time of discharge becomes small. Therefore, the bubbles become easier to discharge. Further, in the third variation, when the air bubbles are discharged only to the side of the suction port 13, the amount of air bubbles to be sucked again can be suppressed. As a result, the centrifugal pump 1 according to the third modification can suppress the occurrence of suction failure and discharge failure and stably exhibit the ability. Further, in the third modification, the amount of gas remaining in the central region CP can be reduced, so that the ability of the pump can be suppressed from being lowered.

Fig. 9 is a schematic cross-sectional view showing a fourth modification of the pump head according to the embodiment of the present invention. The fourth variation is the same as that of the above embodiment, but differs in that a plurality of first openings 10 and 10a are provided. In the description of the fourth modification, the description of the configuration similar to the above-described embodiment will be omitted in principle, and the description will be focused on the different configurations.

The pump head 6D is attached to the suction port 13 side of the suction cover 61, and has a first opening 10 and a first opening 10a opened to a portion 65A opposite to the plurality of blades 51 of the movable impeller 5. The first opening portion 10 and the first opening portion 10a are provided on the suction port 13 side of the suction cover 61, and are open to the plane 61a opposite to the plurality of blades 51 of the movable impeller 5.

Further, the pump head 6D is located at a portion 65B that is present in a direction orthogonal to the center line CL, and has a second opening portion 11 opened. Specifically, the second opening portion 11 is opened in the direction orthogonal to the center line CL and on the second side surface 8b. That is, in the present modification, the second side face 8b corresponds to the portion 65B of the pump head 6D that exists in the direction orthogonal to the center line CL.

The center C1 of the first opening portion 10 is formed on the circumference of the diameter D1 centering on the center line CL. Further, the center C5 of the first opening portion 10a is formed on the circumference of the diameter D4 centering on the center line CL. Further, the first opening 10 is opened in the vicinity of the central region CP of the movable impeller 5. The second opening 11 is opened in a direction orthogonal to the center line CL, and the center C2 of the second opening 11 is formed at a position R from the second end surface 7b. Further, a screw portion 31 is formed in the second opening portion 11.

The suction cover 61 is formed with an exhaust hole 12a, an exhaust hole 12b, and an exhaust hole 12i. The cross section of the exhaust hole 12a, the exhaust hole 12b, and the exhaust hole 12i orthogonal to the extending direction is circular. The suction cover 61 is connected to the exhaust hole 12a, the exhaust hole 12b, and the exhaust hole 12i to form the passage 12. The vent hole 12a is a hole having a length L1 and a diameter d1 extending from the first opening portion 10 toward the second end surface 7b. The vent hole 12b is a hole having a length L2 and a diameter d1 extending from the second opening portion 11 toward the suction port 13. The vent hole 12i is a hole having a length L1 and a diameter d1 extending from the first opening portion 10a toward the second end surface 7b. An end portion of the vent hole 12a opposite to the first opening portion 10 and an end portion of the vent hole 12b opposite to the second opening portion 11 are attached to the suction cover 61, and are connected at an angle α1. Further, the end portion of the exhaust hole 12i opposite to the first opening portion 10a and the exhaust hole 12b are connected to the suction cover 61, and are connected at an angle α1. Thereby, the exhaust hole 12a, the exhaust hole 12b, and the exhaust hole 12i are connected to each other, and are exposed to the first opening 10 and the first opening 10a of the recess 62a and the second surface 8b exposed. The opening portion 11 is in communication.

The length L1 of the vent hole 12a and the vent hole 12i is shorter than the length LH from the plane 61a to the second end face 7b. The length L2 of the vent hole 12b is shorter than the length LW from the second side face 8b to the inner face 61b. In the present embodiment, the diameter d1 of the exhaust hole 12a, the exhaust hole 12b, and the exhaust hole 12i are the same size. However, the diameter d1 is not limited thereto, and may be different diameters. Further, the angle α1 is connected at 90°, but is not limited thereto, and may be, for example, an acute angle or an obtuse angle.

The first opening 10, the first opening 10a, the exhaust hole 12a, the exhaust hole 12b, and the exhaust hole 12i are formed in the pump head 6D, whereby the centrifugal pump 1 is exhausted from the pump chamber 9 through the exhaust hole 12a and the exhaust hole 12a. The hole 12b and the vent hole 12i discharge the gas remaining in the central region CP of the movable impeller 5 to the outside of the pump head 6D. Further, it is possible to suppress the air bubbles discharged from the second opening portion 11 from entering the suction port 13 again. As a result, the centrifugal pump 1 according to the fourth modification can stably exhibit the ability by suppressing the suction failure and the discharge failure. Moreover, in the fourth variation, the discharge amount of the air bubbles can be increased as compared with the case where only one first opening portion is opened. As a result, in the fourth modification, the amount of gas remaining in the central region CP can be reduced, so that the ability of the pump can be more preferably suppressed. Further, in the fourth variation, when the bubble is discharged only from the suction port side, the amount of bubbles that rise to the surface of the water increases. Therefore, in the fourth modification, the amount of the bubbles remaining in the liquid can be made small, so that the amount of the gas dissolved in the liquid can be suppressed.

[Examples]

In order to evaluate the performance of the centrifugal pump of the present invention, an air injection test was performed as the first performance test and the second performance test. Fig. 10 is a view showing the appearance of the apparatus in the first and second performance tests of the centrifugal pump of the present invention. As shown in Fig. 10, the performance test of the centrifugal pump 1A is carried out by immersing the pump head 6E of the centrifugal pump 1A in a fluid (clean water) 25 accumulated in the acrylic tank tank 24. The fluid 25 circulates in the tank tank 24, thereby forcibly injecting air into the centrifugal pump 1A, whereby the ability of the centrifugal pump 1A is measured to decrease. The centrifugal pump 1A has a discharge amount of 250 L/min, a total head of 23 m, a rotation speed of 2900 min ^-1 , and a motor output of 3.7 kW. Further, the tank box 24 has a box diameter Db of 780 mm and a box height Hb of 470 mm. Further, air is connected to the centrifugal pump 1A from the water by connecting a hose to an air compressor (not shown) having an adjustable air amount.

The positional relationship between the tank box 24 and the centrifugal pump 1A is high from the bottom of the tank to the liquid level. The degree h1 is 370 mm, the height h2 from the second end face 7b of the pump head 6E to the liquid surface is 170 mm, the height h3 from the liquid surface to the upper end of the tank is 100 mm, and the height h4 from the bottom of the tank to the pump head 6E The height h5 of 200 mm from the second end face 7b of the pump head 6E to the upper end of the tank is 270 mm. Further, the circulation of the fluid 25 is performed by connecting the piping 26 to the connecting member 18 of the centrifugal pump 1A and returning to the tank tank 24 again. Further, in the pipe 26, the pressure gauge 27 is attached to measure the discharge pressure of the pump, and the valve 28 is attached to adjust the flow rate of the pump. Further, when the pipe 26 is returned to the fluid 25, the return port of the pipe 26 is moved away from the suction port so as not to affect the pump performance as much as possible, and the intrusion of air due to the influence of the cycle is excluded as much as possible.

The shape and structure of the suction cover 61 used in the first performance test are the same as those of the suction cover 61 shown in FIG. Therefore, the description is omitted. In the suction cover 61, there are four passages for discharging air bubbles from the first opening portion 10 to the second opening portion 11, and four passages for discharging air bubbles from the first opening portion 10 to the second discharge port 70. The diameter D1 of the center C1 of the first opening portion 10 is 90 mm, and the diameter d1 of the passage 12 is 11 mm. Further, the diameter D of the movable impeller 5 is 166 mm, and the diameter Ds of the start end of the blade 51 of the movable impeller 5 (the circle connecting the end on the center line CL side) is 70 mm. In the first embodiment, the second discharge port 70 is closed, and only the air bubbles are discharged from the second opening portion 11. The second embodiment is an example in which bubbles are discharged from both the second opening portion 11 and the second discharge port 70. The comparative example is an example in which the second opening portion 11 and the second discharge port 70 are closed. Further, in the first embodiment, the second embodiment, and the comparative example, the closing of the second opening portion 11 and the second discharge port 70 is performed by screwing the plug 30 into the screw portion 31.

The air injection test was carried out by operating the centrifugal pump 1A at 50 Hz and adjusting the valve 28 so that the flow rate became 50 L/min, and then fixing the valve 28 from 30 Hz to 50 Hz by the inverter. Up to this, the number of revolutions of the motor is adjusted at intervals of 5 Hz, and air is injected through the air compressor via the air flow meter. The result is shown in Fig. 11. The discharge pressure (m) in the figure indicates before the injection of air and after the injection of the maximum air injection amount (L/min). Furthermore, the discharge pressure (m) is the ratio of the reading of the pressure gauge 27 to the proportion of the clean water used in the test. And the value of the meter conversion.

In the first performance test, since the centrifugal pump 1A is operated based on the frequency (rotation speed), the discharge pressure (m) changes depending on the presence or absence of the passage. Therefore, the performance evaluation of the centrifugal pump of the present invention investigates the decrease in the discharge pressure (m) with respect to the maximum air injection amount (L/min). In other words, the larger the maximum air injection amount (L/min) and the smaller the decrease in the discharge pressure (m), the more effective, and the decrease in the discharge pressure (m) is 1.0 (m) or less. In the first embodiment and the second embodiment of the embodiment of the present invention, even when the maximum air injection amount (L/min) is at most 10.0 (L/min), the discharge pressure (m) is decreased by 1.0 (m) or less. On the other hand, in the comparative example in which all of the second openings were closed, even if the maximum air injection amount (L/min) was 0.4 (L/min), the drop in the discharge pressure (m) exceeded 1.0 (m). Therefore, it can be seen that the first embodiment and the second embodiment are effective as compared with the comparative example.

Further, in the first embodiment, when the air bubbles are discharged from the second opening portion 11, it is possible to visually confirm the rise to the liquid surface. In the second embodiment, when the air bubbles are discharged from the second discharge port 70, it is possible to visually recognize the rise to the liquid surface and the suction from the suction port 13. In other words, in the first embodiment and the second embodiment, air bubbles are discharged in a direction orthogonal to the center line CL, and the air bubbles rise in the water tank, so that the amount of gas sucked into and dissolved from the suction port 13 is suppressed. Therefore, it is possible to suppress the inhalation failure and stably exert the ability of the pump. In the comparative example, all of the second openings 11 are clogged, so that one of the bubbles is discharged from the discharge port 14. Further, in the first embodiment, as compared with the comparative example, it is understood that even if air is injected about 10 times, the ability of the pump is suppressed from being lowered. Further, in the comparative example, if the maximum air injection amount (L/min) exceeds 0.8 (L/min), the discharge pressure (m) is largely lowered.

Next, the second performance test will be described. The second performance test was carried out by a centrifugal pump having a discharge amount of 100 L/min, a total head of 10 m, a rotation speed of 2900 min ^-1 , and a motor output of 3.7 kW. The result is shown in FIG. In the air injection test, the size of the tank, the arrangement of the tank and the centrifugal pump, and the connection method of the piping are the same as those of the example shown in FIG. 10 described above, and thus the description thereof is omitted.

Fig. 12 is a cross-sectional view showing a cross section showing one half of the width direction of the pump head in the second performance test. As shown in FIG. 12, the pump head 6F is formed by combining the outer casing 600 and the suction cover 610. A second opening 11b and an exhaust hole 12d are formed in the outer casing 600. The first cover 10, the second opening 11, the second discharge port 70, the exhaust hole 12b, the exhaust hole 12c, and the exhaust hole 12e are formed in the suction cover 610. Further, the diameters of the exhaust hole 12b, the exhaust hole 12c, the exhaust hole 12d, and the exhaust hole 12e are both d1. Further, as shown in FIG. 12, the pipe 17a and the L-shaped pipe 16a are attached to the second opening 11b, and air bubbles are discharged from the discharge port 29 of the L-shaped pipe 16a to the atmosphere. The closing of the second discharge port 70 corresponds to the insertion of the plug 30. Further, the first opening portion 10 is formed at four locations on the plane 61a, and is formed at an interval of 90° on the circumference of the diameter D1 centering on the center line CL of the shaft 3. Four vent holes 12b, vent holes 12c, vent holes 12d, and vent holes 12e are formed in each of four. In the suction cover 610, there are four passages 12 for discharging air bubbles from the first opening portion 10 to the second opening portion 11, and the passage 12 for discharging the air from the first opening portion 10 to the discharge port 29 via the second opening portion 11b is four. article. Further, there are four passages 12 for discharging air bubbles from the first opening portion 10 to the second discharge port 70. The diameter D1 of the center C1 of the first opening 10 is 90 mm, and the diameter d1 of the passage is 11 mm. Further, the diameter D of the movable impeller 5 is 135 mm, and the diameter Ds of the beginning end of the blade 51 of the movable impeller 5 (the circle connecting the end on the center line CL side) is 70 mm.

The first embodiment is an example in which bubbles are discharged only from the discharge port 29 of the L-shaped pipe 16a. The second embodiment is an example in which bubbles are discharged only from the second opening portion 11. The comparative example is an example in which the second opening portion 11, the discharge port 29, and the second discharge port 70 are closed. The previous example is an example in which only the second discharge port 70 is opened. Further, when the prior art, the comparative example, the first embodiment, and the second embodiment are implemented, the closing of the second opening portion 11, the discharge port 29, and the second discharge port 70 is performed by attaching the plug 30.

In the same manner as the air injection test of the first performance test, the air injection test of the second performance test was performed by operating the centrifugal pump 1A at 50 Hz and adjusting the valve 28 at a flow rate of 50 L/min. After that, the valve 28 is fixed by the inverter The number of revolutions of the motor is adjusted at intervals of 5 Hz from 30 Hz to 50 Hz, thereby injecting air through the air compressor via the air flow meter. Further, the measurement of the discharge pressure (m) is also the same as the measurement performed in the first performance test. The result is shown in FIG.

In the second performance test, as in the first performance test, the centrifugal pump 1A is operated based on the frequency (rotation speed). Therefore, the discharge pressure (m) changes depending on the presence or absence of the passage. Therefore, in the second performance test, similarly to the first performance test, the performance evaluation of the centrifugal pump was conducted to evaluate the decrease in the discharge pressure (m) with respect to the maximum air injection amount (L/min). In other words, the larger the maximum air injection amount (L/min) and the smaller the decrease in the discharge pressure (m), the more effective, and the decrease in the discharge pressure (m) is 1.0 (m) or less. In the first embodiment and the second embodiment of the embodiment of the present invention, even when the maximum air injection amount (L/min) is the maximum of 13.0 (L/min), the discharge pressure (m) is reduced by 1.0 (m) or less.

Further, in the first embodiment, it is possible to visually confirm that the bubble is discharged from the discharge port 29 together with the liquid. In the second embodiment, when the air bubbles are discharged from the second opening portion 11, it is possible to visually recognize the rise to the liquid surface. In the comparative example, the discharge port 29, the second opening portion 11, and the second discharge port 70 are all closed, so that one part of the bubble is discharged from the discharge port. Comparing the results of Example 1, Example 2, and Comparative Example, it is understood that the results of Examples 1 and 2 are better than those of the comparative examples. Further, it can be seen that even in the case of Example 1, the air was injected about twice as much as the comparative example, and the ability of the pump was suppressed from being lowered. Further, in the first embodiment, compared with the prior art, the discharged air bubbles are suppressed from flowing in again from the suction port. Further, the amount of the dissolved gas is released to the surface of the water and is released to the atmosphere, so that it is reduced. As a result, the ability of the pump can be stably exhibited by suppressing the suction failure. Further, in the comparative example, if the maximum air injection amount (L/min) exceeds 3.0 (L/min), the discharge pressure (m) is largely lowered.

1‧‧‧centrifugal pump

2‧‧‧Electric motor

2a‧‧‧Flange

3‧‧‧Axis

3b‧‧‧ Body Department

3c‧‧‧End

3d‧‧‧screws

3e‧‧‧ lock key

4‧‧‧ Protective cover

5‧‧‧moving impeller

6‧‧‧ pump head

7‧‧‧ end face

7a‧‧‧1st end

7b‧‧‧2nd end

8‧‧‧ side

8a‧‧‧1st side

8b‧‧‧2nd side

10‧‧‧1st opening

11‧‧‧2nd opening

12‧‧‧ pathway

13‧‧‧Inhalation

14‧‧‧Spray outlet

15‧‧‧Support components

16‧‧‧L-type piping

17‧‧‧Pipe

18‧‧‧Connecting components

19a, 19b‧‧‧ screw

20a, 20b‧‧‧ nuts

21‧‧‧ moving impeller nut

50b‧‧‧Lock keyway

60‧‧‧ Shell

61‧‧‧Intake cover

65A‧‧‧ parts

65B‧‧‧ parts

CL‧‧‧ center line

D‧‧‧diameter

Claims (10)

A centrifugal pump comprising: a suction port that sucks a fluid; and a moving impeller having a plurality of blades at least on the suction port side and rotating around a specific axis passing through the suction port, thereby sucking from the above The port sucks the fluid and ejects the fluid in a direction orthogonal to the axis; the pump head has the suction port and houses the movable impeller; and the first opening is formed by the plurality of blades on the suction port side Opening to a portion of the pump head; the second opening is open at a portion of the pump head that exists in a direction orthogonal to the axis and opposite to the suction port side; and a passage The first opening is connected to the second opening. The centrifugal pump according to claim 1, wherein the passage is two or more and ten or less. The centrifugal pump according to claim 1 or 2, wherein the diameter of the circle connecting the end portions on the inner diameter side of the vane of the impeller is Ds, and the diameter of the impeller is D, The first opening is opened in a range of 1.0‧Ds or more and 1.0‧D or less around the axis. The centrifugal pump according to claim 1 or 2, wherein the cross section of the passage orthogonal to the direction in which the passage extends is circular, and the diameter of the cross section is 10% or more and 50% or less with respect to the diameter of the discharge port from which the fluid is discharged. The centrifugal pump according to claim 4, wherein the cross section of the passage orthogonal to the direction in which the passage extends is circular, and the diameter of the cross section is 10% or more and 50% or less with respect to the diameter of the discharge port from which the fluid is discharged. A centrifugal pump comprising: a suction port that draws in fluid; The movable impeller has a plurality of blades at least on the suction port side, and rotates around a specific axis passing through the suction port, thereby sucking the fluid from the suction port and ejecting the direction in a direction orthogonal to the axis a pump head having the suction port and accommodating the movable impeller; the first opening portion is open to a portion of the pump head that faces the plurality of blades on the suction port side; and the second opening portion is Opening a portion of the pump head existing in a direction orthogonal to the axis; and a passage connecting the first opening to the second opening. The centrifugal pump according to claim 6, wherein the passage is two or more and ten or less. The centrifugal pump according to claim 6 or 7, wherein when the diameter of the circle connecting the end portions on the inner diameter side of the vane of the impeller is Ds and the diameter of the impeller is D, The first opening is opened in a range of 1.0‧Ds or more and 1.0‧D or less around the axis. The centrifugal pump according to claim 6 or 7, wherein the cross section of the passage orthogonal to the direction in which the passage extends is circular, and the diameter of the cross section is 10% or more and 50% or less with respect to the diameter of the discharge port from which the fluid is discharged. The centrifugal pump according to claim 9, wherein the cross section of the passage orthogonal to the direction in which the passage extends is circular, and the diameter of the cross section is 10% or more and 50% or less with respect to the diameter of the discharge port from which the fluid is discharged.