JP7240130B2 - impeller used in pump - Google Patents

Description

The present invention relates to impellers used in pumps for transferring liquids.

In general, impellers used in pumps are semi-open impellers that do not have side plates (also called front shrouds), or full-open impellers that do not have side plates and have a smaller main plate (also called back shrouds). is the impeller of However, these types of impellers are difficult to assemble and have poor pump performance. Therefore, a reverse-open impeller with relatively good pump performance is sometimes used for the pump. A reverse-open impeller is an impeller that does not have a main plate and has blades fixed to side plates.

U.S. Pat. No. 5,605,444

However, since this type of impeller is subjected to a large thrust force directed toward the motor, the pump must be provided with a bearing having a large allowable load capable of receiving not only the radial force but also the thrust force. For example, angular contact ball bearings are generally expensive and require at least two opposite angular contact ball bearings to receive thrust forces in both directions. This not only increases the cost of the overall pump, but also makes the pump itself bulky in order to build a robust bearing system. Furthermore, a device is required to cool the bearings, increasing the cost of the pump.

Accordingly, the present invention provides an impeller capable of reducing thrust force.

In one aspect, there is provided a double star impeller used in a pump, comprising a plurality of blades, a star-shaped main plate having a hole in which a rotating shaft of the pump is fitted, and a star-shaped fluid inlet. the outer diameter of the main plate is smaller than the outer diameter of the side plate, the main plate includes a plurality of protrusions that contact the plurality of blades, respectively, and the protrusions are provided in the double A double star impeller is provided having a shape projecting outward in the radial direction of the star impeller, wherein the plurality of projections are adjacent to each other.
In one aspect, the area of the outer surface of the side plate is larger than the area of the outer surface of the main plate.
In one aspect, the side plate has a plurality of recesses located between the plurality of blades, and the recesses have a shape that is recessed inward in the radial direction of the double star impeller. are doing .
In one aspect, the double star impeller is a centrifugal impeller without balance holes.

In one aspect, a single star-shaped impeller used in a pump, comprising a plurality of blades, a circular main plate formed with a hole into which the rotating shaft of the pump is fitted, and a star-shaped side plate having a fluid inlet. wherein the outer diameter of the main plate is smaller than the outer diameter of the side plate.
In one aspect, the area of the outer surface of the side plate is larger than the area of the outer surface of the main plate.
In one aspect, the side plate has a plurality of recesses located between the plurality of blades, and the recesses have a shape that is recessed inward in the radial direction of the single star impeller. ing.
In one aspect, the single star impeller is a centrifugal impeller without balance holes.

In one aspect, a circular impeller used in a pump, comprising a plurality of blades, a circular main plate having a hole for fitting the rotating shaft of the pump, and a circular side plate having a fluid inlet, The plurality of blades protrude radially outward from the outer peripheral edge of the main plate, the outer diameter of the main plate is smaller than the outer diameter of the side plate, and the area of the outer surface of the side plate is equal to the outer surface area of the main plate. A circular impeller is provided that is larger than the area .
In one aspect, the circular impeller is a centrifugal impeller without balance holes.

According to the present invention, since the diameter of the main plate is smaller than the diameter of the side plate, the difference between the force with which the liquid pushes the side plate toward the main plate and the force with which the liquid pushes the main plate toward the side plate becomes small. As a result, the thrust force transmitted from the impeller to the bearing can be reduced. Moreover, according to the present invention, it is not necessary to provide a balance hole in the impeller, and a decrease in pump efficiency can be prevented.

FIG. 3 is a schematic diagram illustrating one embodiment of a pump group including three pumps; FIG. 2 is a cross-sectional view showing a pump with a circular impeller; It is the figure which looked at the circular impeller shown in FIG. 2 from the suction side. It is the figure which looked at the circular impeller shown in FIG. 2 from the discharge side. FIG. 3 is a cross-sectional view showing a pump with a single star impeller; FIG. 6 is a view of the single star impeller shown in FIG. 5 as viewed from the suction side; It is the figure which looked at the single star type impeller shown in FIG. 5 from the discharge side. FIG. 3 is a cross-sectional view showing a pump with double star impellers; FIG. 9 is a view of the double star impeller shown in FIG. 8 as seen from the suction side; FIG. 9 is a view of the double star impeller shown in FIG. 8 viewed from the discharge side; FIG. 3 is a schematic diagram of a circular impeller, a single star impeller, and a double star impeller compared under the same discharge flow rate condition. Fig. 2 is a graph illustrating the relationship between the specific speed of three pumps, each having a circular impeller, a single star impeller, and a double star impeller, and the thrust force applied to the bearings of each pump; 13 is a pump selection graph showing the first specific speed range, the second specific speed range, and the third specific speed range shown in FIG. 12 by pump head and discharge flow rate. FIG. 3 is a schematic diagram showing a pump selection device that selects and displays one pump from a pump group;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic diagram illustrating one embodiment of a pump group 100 including pump 1, pump 2, and pump 3. As shown in FIG. These three pumps 1, 2, 3 each have three different types of impellers and have different specific speeds. More specifically, the specific speed of pump 1 is higher than the specific speed of pump 2 , and the specific speed of pump 2 is higher than the specific speed of pump 3 .

Each pump 1, 2, 3 included in the pump group 100 is used for transferring liquid. The user can select the optimum one from the three pumps 1, 2, 3 based on the required specific speed. In this embodiment, the pump group 100 includes three pumps 1, 2, and 3 having different specific speeds, but the pump group 100 includes only two of these three pumps 1, 2, and 3. or, in addition to the three pumps 1, 2, 3, one or more pumps with different specific speeds may be further included.

FIG. 2 is a sectional view showing the pump 1. FIG. The pump 1 of this embodiment is a single-stage centrifugal pump. This pump 1 includes a circular impeller 10, a pump casing 11 housing the circular impeller 10, a rotary shaft 12 to which the circular impeller 10 is fixed, and two bearings 15 that support the rotary shaft 12. there is Two bearings 15 are held in a bearing housing 16 fixed to the pump casing 11 . The two bearings 15 are arranged apart from each other along the axis of rotation 12 . Each bearing 15 is composed of a ball bearing. A mechanical seal 17 as a shaft sealing device is arranged on the back side of the circular impeller 10 . The mechanical seal 17 has the function of sealing the gap between the rotating shaft 12 and the pump casing 11 while allowing the rotating shaft 12 to freely rotate.

The pump casing 11 has a suction port 11A communicating with the circular impeller 10, a volute chamber 11C surrounding the circular impeller 10, and a discharge port 11B connected to the volute chamber 11C. One end of the rotating shaft 12 is fixed to the circular impeller 10 so that the circular impeller 10 and the rotating shaft 12 can rotate integrally. The other end of the rotating shaft 12 is connected to a prime mover (for example, an electric motor) not shown. When the circular impeller 10 and the rotary shaft 12 are rotated by the prime mover, liquid is sucked into the circular impeller 10 through the suction port 11A. Velocity energy is imparted to the liquid by the rotating circular impeller 10, and the velocity energy is converted to pressure as the liquid flows through the volute chamber 11C. The pressurized liquid is ejected from the ejection port 11B.

3 is a view of the circular impeller 10 shown in FIG. 2 as seen from the suction side, and FIG. 4 is a view of the circular impeller 10 shown in FIG. 2 as seen from the discharge side. The circular impeller 10 includes a plurality of blades 21 , a circular main plate 24 formed with a hole 22 into which the rotating shaft 12 is fitted, and a circular side plate 27 having a fluid inlet 25 . A plurality of blades 21 are arranged at regular intervals around the hole 22 (that is, around the rotating shaft 12). A plurality of blades 21 are arranged between side plate 27 and main plate 24 and fixed to both side plate 27 and main plate 24 .

2 and 3, the circular impeller 10 is a centrifugal impeller without balance holes. Therefore, the circular impeller 10 can improve pump efficiency. In addition, the circular impeller 10 has no balance holes and is therefore suitable for transporting slurries containing particles. If the circular impeller 10 has a balance hole, the balance hole will be worn when the slurry passes through the balance hole, the balance hole will gradually enlarge, and the pump efficiency will decrease. Also, the slurry may clog the balance hole, in which case the thrust force increases and the bearing 15 is damaged. Since the circular impeller 10 does not have a balance hole, such a problem does not occur. Therefore, the pump 1 having the circular impeller 10 without balance holes can be suitably used as a slurry pump.

The outer diameter of the main plate 24 is smaller than the outer diameter of the side plate 27 , and the area of the outer surface 24 a of the main plate 24 is smaller than the area of the outer surface 27 a of the side plate 27 . Outermost ends 21 a of the plurality of blades 21 are on outer peripheral edges 27 b of side plates 27 . The outer peripheral edge 24b of the main plate 24 is located radially inward of the outer peripheral edge 27b of the side plate 27 and the outermost ends 21a of the plurality of blades 21 . That is, as shown in FIG. 4, the blade 21 protrudes radially outward from the outer peripheral edge 24b of the main plate 24. As shown in FIG.

When the pump 1 equipped with the circular impeller 10 is transferring liquid, the outer surface 27a of the side plate 27 and the outer surface 24a of the main plate 24 of the circular impeller 10 are under liquid pressure. Since the area of the outer surface 24a of the main plate 24 is smaller than the area of the outer surface 27a of the side plate 27, a thrust force that pushes the entire circular impeller 10 from the side plate 27 toward the main plate 24 is generated. This thrust force is received by the bearing 15 through the rotating shaft 12 shown in FIG.

The thrust force transmitted from the circular impeller 10 to the bearing 15 can vary depending on the ratio of the area of the outer surface 27 a of the side plate 27 and the area of the outer surface 24 a of the main plate 24 . A ratio between the area of the outer surface 27a of the side plate 27 and the area of the outer surface 24a of the main plate 24 is predetermined so that the thrust force is less than the allowable load limit of the bearing 15. FIG. In other words, the ratio of the area of the outer surface 27a of the side plate 27 to the area of the outer surface 24a of the main plate 24 is such that the thrust force transmitted from the circular impeller 10 to the bearing 15 is less than the allowable load limit of the bearing 15. The circular impeller 10 having such a shape can reduce the thrust force applied to the bearing 15 and eliminate the need to use a bearing with a large allowable load in the pump 1 .

FIG. 5 is a sectional view showing the pump 2. As shown in FIG. The pump 2 of this embodiment is a single-stage centrifugal pump. This pump 2 includes a single star impeller 30, a pump casing 31 housing the single star impeller 30, a rotating shaft 32 to which the single star impeller 30 is fixed, and a 2 that supports the rotating shaft 32. It has two bearings 35 . Two bearings 35 are held in a bearing housing 36 fixed to the pump casing 31 . The two bearings 35 are arranged apart from each other along the rotation axis 32 . Each bearing 35 is composed of a ball bearing. A mechanical seal 37 is arranged as a shaft sealing device on the back side of the single star impeller 30 . The mechanical seal 37 has the function of sealing the gap between the rotating shaft 32 and the pump casing 31 while allowing the rotating shaft 32 to rotate freely.

The pump casing 31 has a suction port 31A communicating with the single star impeller 30, a volute chamber 31C surrounding the single star impeller 30, and a discharge port 31B connected to the volute chamber 31C. One end of the rotating shaft 32 is fixed to the single star impeller 30, and the single star impeller 30 and the rotating shaft 32 are rotatable together. The other end of the rotating shaft 32 is connected to a prime mover (for example, an electric motor) not shown. When the single star impeller 30 and the rotating shaft 32 are rotated by the prime mover, the liquid is sucked into the single star impeller 30 through the suction port 31A. Velocity energy is imparted to the liquid by the rotating single star impeller 30, and the velocity energy is converted to pressure as the liquid flows through the volute chamber 31C. The pressurized liquid is ejected from the ejection port 31B.

6 is a view of the single star impeller 30 shown in FIG. 5 as seen from the suction side, and FIG. 7 is a view of the single star impeller 30 shown in FIG. 5 as seen from the discharge side. The single star impeller 30 includes a plurality of blades 41 , a circular main plate 44 formed with a hole 42 into which the rotating shaft 32 is fitted, and a star-shaped side plate 47 having a fluid inlet 45 . A plurality of blades 41 are arranged at regular intervals around the hole 42 (that is, around the rotating shaft 32). A plurality of blades 41 are arranged between side plate 47 and main plate 44 and fixed to both side plate 47 and main plate 44 . As can be seen from FIGS. 6 and 7, the single star impeller 30 is a centrifugal impeller without balance holes. Therefore, the single star impeller 30 is not only suitable for transferring slurry, but also can improve pump efficiency. The pump 2 equipped with the single star impeller 30 can be suitably used as a slurry pump.

The outer diameter of the main plate 44 is smaller than the outer diameter of the side plate 47 , and the area of the outer surface 44 a of the main plate 44 is smaller than the area of the outer surface 47 a of the side plate 47 . Outermost ends 41a of the plurality of blades 41 are on the outer peripheral edge 47b of the side plate 47. As shown in FIG. The outer peripheral edge 44b of the main plate 44 is located radially inside the outer peripheral edge 47b of the side plate 47 and the outermost ends 41a of the plurality of blades 41 . That is, as shown in FIG. 7, the blade 41 protrudes radially outward from the outer peripheral edge 44b of the main plate 44. As shown in FIG.

When the pump 2 with the single star impeller 30 is transferring liquid, the outer surface 47a of the side plate 47 and the outer surface 44a of the main plate 44 of the single star impeller 30 are under pressure of the liquid. Since the area of the outer surface 44 a of the main plate 44 is smaller than the area of the outer surface 47 a of the side plate 47 , a thrust force is generated that pushes the entire single star impeller 30 in the direction from the side plate 47 toward the main plate 44 . This thrust force is received by the bearing 35 through the rotating shaft 32 shown in FIG.

Pump 2 with single star impeller 30 has a lower specific speed than pump 1 with circular impeller 10 . Generally, under the same discharge flow rate condition, the lower the specific speed, the larger the outer diameter of the impeller. As a result, the thrust force transmitted from the impeller to the bearing increases. If this thrust force exceeds the allowable load limit of the bearing, the bearing will be damaged. Therefore, the single star impeller 30 has a star-shaped side plate 47 in order to reduce the thrust force.

As shown in FIGS. 6 and 7 , the star-shaped side plate 47 has a plurality of depressions 49 positioned between the plurality of wings 41 . Each recessed portion 49 is located between two adjacent blades 41 and has a shape recessed inward in the radial direction of the single star impeller 30 . These recessed portions 49 contribute to reducing the area of the outer surface 47 a of the side plate 47 . As described above, under the same discharge flow rate condition, the outer diameter of the impeller increases as the specific speed decreases. Therefore, in this embodiment, the outer diameter of the single star impeller 30 is larger than the outer diameter of the circular impeller 10. The pressure receiving area of the outer surface 47 a of the side plate 47 is reduced, and as a result, the thrust force transmitted from the single star impeller 30 to the bearing 35 can be made less than the allowable load limit of the bearing 35 .

The thrust force transmitted from the single star impeller 30 to the bearing 35 can vary depending on the ratio of the area of the outer surface 47 a of the side plate 47 and the area of the outer surface 44 a of the main plate 44 . A ratio of the area of the outer surface 47 a of the side plate 47 to the area of the outer surface 44 a of the main plate 44 is predetermined so that the thrust force is less than the allowable load limit of the bearing 35 . In other words, the ratio of the area of the outer surface 47a of the side plate 47 to the area of the outer surface 44a of the main plate 44 is such that the thrust force transmitted from the single star impeller 30 to the bearing 35 is less than the allowable load limit of the bearing 35. be. The single star impeller 30 with the star-shaped side plates 47 can reduce the thrust force applied to the bearing 35 while achieving a low specific speed.

FIG. 8 is a sectional view showing the pump 3. As shown in FIG. The pump 3 of this embodiment is a single-stage centrifugal pump. The pump 3 includes a double star impeller 50, a pump casing 51 housing the double star impeller 50, a rotating shaft 52 to which the double star impeller 50 is fixed, and a rotating shaft 52. It has two supporting bearings 55 . Two bearings 55 are held in a bearing housing 56 fixed to the pump casing 51 . The two bearings 55 are arranged apart from each other along the rotation axis 52 . Each bearing 55 is composed of a ball bearing. A mechanical seal 57 is arranged as a shaft sealing device on the back side of the double star impeller 50 . The mechanical seal 57 has the function of sealing the gap between the rotating shaft 52 and the pump casing 51 while allowing the rotating shaft 52 to freely rotate.

The pump casing 51 has a suction port 51A communicating with the double star impeller 50, a volute chamber 51C surrounding the double star impeller 50, and a discharge port 51B connected to the volute chamber 51C. . One end of the rotating shaft 52 is fixed to the double star impeller 50, and the double star impeller 50 and the rotating shaft 52 are rotatable together. The other end of the rotating shaft 52 is connected to a prime mover (for example, an electric motor) not shown. When the double star impeller 50 and the rotating shaft 52 are rotated by the prime mover, the liquid is sucked into the double star impeller 50 through the suction port 51A. Velocity energy is imparted to the liquid by the rotating double star impeller 50, and the velocity energy is converted to pressure as the liquid flows through the volute chamber 51C. The pressurized liquid is ejected from the ejection port 51B.

9 is a view of the double star impeller 50 shown in FIG. 8 as seen from the suction side, and FIG. 10 is a view of the double star impeller 50 shown in FIG. 8 as seen from the discharge side. . The double star impeller 50 includes a plurality of blades 61 , a star-shaped main plate 64 formed with a hole 62 into which the rotating shaft 52 is fitted, and a star-shaped side plate 67 having a fluid inlet 65 . A plurality of blades 61 are arranged at regular intervals around the hole 62 (that is, around the rotating shaft 52). A plurality of wings 61 are arranged between side plate 67 and main plate 64 and are fixed to both side plate 67 and main plate 64 . As can be seen from FIGS. 9 and 10, the double star impeller 50 is a centrifugal impeller without balance holes. Therefore, the double star impeller 50 is not only suitable for transferring slurry, but also can improve pump efficiency. The pump 3 with the double star impeller 50 can be suitably used as a slurry pump.

The outer diameter of the main plate 64 is smaller than the outer diameter of the side plate 67 , and the area of the outer surface 64 a of the main plate 64 is smaller than the area of the outer surface 67 a of the side plate 67 . Outermost ends 61 a of the plurality of blades 61 are on outer peripheral edges 67 b of side plates 67 . The outer peripheral edge 64b of the main plate 64 is positioned radially inward of the outer peripheral edge 67b of the side plate 67 and the outermost ends 61a of the plurality of blades 61 . That is, as shown in FIG. 10, the blade 61 protrudes radially outward from the outer peripheral edge 64b of the main plate 64. As shown in FIG.

When the pump 3 with the double star impeller 50 is transferring liquid, the outer surface 67a of the side plate 67 and the outer surface 64a of the main plate 64 of the double star impeller 50 are under pressure of the liquid. Since the area of the outer surface 64a of the main plate 64 is smaller than the area of the outer surface 67a of the side plate 67, a thrust force that pushes the entire double star impeller 50 in the direction from the side plate 67 toward the main plate 64 is generated. This thrust force is received by a bearing 55 through a rotating shaft 52 shown in FIG.

Pump 3 with double star impeller 50 has a lower specific speed than pump 2 with single star impeller 30 . As described above, generally, under the same discharge flow rate condition, the lower the specific speed, the larger the outer diameter of the impeller. As a result, the thrust force transmitted from the impeller to the bearing increases. Therefore, the double star impeller 50 has a star-shaped side plate 67 and a star-shaped main plate 64 in order to reduce the thrust force.

As shown in FIGS. 9 and 10 , the star-shaped side plate 67 has a plurality of depressions 69 positioned between the plurality of wings 61 . Each recess 69 is positioned between two adjacent blades 61 and has a shape recessed inward in the radial direction of the double star impeller 50 . These recessed portions 69 contribute to reducing the area of the outer surface 67 a of the side plate 67 . That is, since a plurality of recessed portions 69 are formed in the outer peripheral edge 67b of the side plate 67, the pressure receiving area of the outer surface 67a of the side plate 67 is reduced. decreases. However, since the outer diameter of the side plate 67 itself is large, it is difficult to reduce the thrust force below the allowable load limit of the bearing 55 only by forming the recessed portion 69 .

Therefore, the main plate 64 also has a star shape in order to increase the force with which the liquid pushes the outer surface 64a of the main plate 64 . More specifically, the star-shaped main plate 64 has a plurality of protruding portions 71 contacting the plurality of wings 61 respectively. Each protrusion 71 protrudes outward in the radial direction of the double star impeller 50 . These protrusions 71 contribute to increasing the area of the outer surface 64 a of the main plate 64 , unlike the recessed portions 69 formed in the side plate 67 . That is, in order to cancel most of the force of the liquid applied to the side plate 67 having a relatively large pressure receiving area, the main plate 64 is provided with the protrusion 71 to increase the pressure receiving area of the main plate 64 . Most of the force of the liquid pushing the outer surface 67 a of the side plate 67 is canceled by the force of the liquid pushing the main plate 64 . As a result, the thrust force exerted by the double star impeller 50 on the bearing 55 can be less than the allowable load limit of the bearing 55 .

The thrust force transmitted from double star impeller 50 to bearing 55 can vary depending on the ratio of the area of outer surface 67a of side plate 67 to the area of outer surface 64a of main plate 64 . A ratio between the area of the outer surface 67a of the side plate 67 and the area of the outer surface 64a of the main plate 64 is predetermined so that the thrust force is less than the allowable load limit of the bearing 55. FIG. In other words, the ratio of the area of the outer surface 67a of the side plate 67 to the area of the outer surface 64a of the main plate 64 is such that the thrust force transmitted from the double star impeller 50 to the bearing 55 is less than the allowable load limit of the bearing 55. is. The double star impeller 50 with the star-shaped side plates 67 and the star-shaped main plate 64 can reduce the thrust force applied to the bearings 55 while achieving a low specific speed.

A pump group 100 comprising at least a pump 1 with a circular impeller 10, a pump 2 with a single star impeller 30, and a pump 3 with a double star impeller 50 absorbs the thrust force through the bearings 15,35,55. It is possible to cover a wide range of specific speeds while staying below the allowable load limit of

FIG. 11 is a schematic diagram of a circular impeller 10, a single star impeller 30, and a double star impeller 50 compared under the same discharge flow rate condition. The specific speed of the pump 1 with the circular impeller 10 is higher than the specific speed of the pump 2 with the single star impeller 30, and the specific speed of the pump 2 with the single star impeller 30 is higher than that of the double star impeller. Higher than pump 3 specific speed with wheel 50 . As can be seen from FIG. 11, under the same discharge flow rate condition, the outer diameter of the impeller increases as the specific speed decreases.

A force F1 and a force F2 are respectively applied from the liquid to the side plate 27 and the main plate 24 of the circular impeller 10 (F1>F2). A difference Δ1 between the force F1 and the force F2 corresponds to the thrust force pushing the circular impeller 10 in the axial direction. A force F3 and a force F4 are applied from the liquid to the side plate 47 and the main plate 44 of the single star impeller 30 (F3>F4). A difference Δ2 between the force F3 and the force F4 corresponds to the thrust force pushing the single star impeller 30 in the axial direction. Side plate 67 and main plate 64 of double star impeller 50 are subjected to force F5 and force F6 from the liquid, respectively (F5>F6). The difference Δ3 between force F5 and force F6 corresponds to the thrust force pushing the double star impeller 50 in the axial direction.

Thrust forces Δ1, Δ2, Δ3 are received by bearings 15, 35, 55, respectively. All of the thrust forces Δ1, Δ2, Δ3 are below the allowable load limits of the bearings 15, 35, 55. In other words, the side plate 27 and the main plate 24 of the circular impeller 10, the side plate 47 and the main plate 44 of the single star impeller 30 are arranged so that the thrust forces Δ1, Δ2, Δ3 are less than the allowable load limits of the bearings 15, 35, 55. , the shape and size of the side plate 67 and the main plate 64 of the double star impeller 50 are determined.

FIG. 12 shows the specific speed of the three pumps 1, 2, 3 with a circular impeller 10, a single star impeller 30 and a double star impeller 50 respectively, and the bearings 15 of each pump 1, 2, 3. , 35, 55 and the thrust force applied thereto. The specific speed of the pump 1 with the circular impeller 10 is within a first specific speed range R1 and the specific speed of the pump 2 with the single star impeller 30 is in a second ratio lower than the first specific speed range R1. Within the speed range R2, the specific speed of the pump 3 with the double star impeller 50 is within a third specific speed range R3 which is lower than the second specific speed range R2.

Within the first specific speed range R1, a pump 1 with a circular impeller 10 is used. Both the side plate 27 and the main plate 24 of the circular impeller 10 are circular, as described with reference to FIGS. 3 and 4 . The circular side plate 27 and the circular main plate 24 have sizes that allow the pump 1 to achieve a specific speed within the first specific speed range R1. However, as shown in the graph of FIG. 12, as the specific speed decreases, the thrust force increases and exceeds the allowable load limit L of the bearing 15 (see FIG. 2).

Therefore, the pump 1 with the circular impeller 10 is switched to the pump 2 with the single star impeller 30 before the thrust force exceeds the allowable load limit L of the bearing 15 . As described with reference to FIGS. 6 and 7, the single star impeller 30 has a star-shaped side plate 47 and a circular main plate 44 . The star-shaped side plate 47 and the circular main plate 44 have sizes and shapes that allow the pump 2 to achieve a specific speed within the second specific speed range R2. However, as shown in the graph of FIG. 12, as the specific speed decreases, the thrust force increases and exceeds the allowable load limit L of the bearing 35 (see FIG. 3).

Therefore, the pump 2 with the single star impeller 30 is switched to the pump 3 with the double star impeller 50 before the thrust force exceeds the allowable load limit L of the bearing 35 . Both the side plate 67 and the main plate 64 of the double star impeller 50 are star-shaped, as described with reference to FIGS. 9 and 10 . The star-shaped side plates 67 and main plate 64 have sizes and shapes that allow the pump 3 to achieve a specific speed within the third specific speed range R3.

Thus, the pumps 1, 2, 3 with the three different types of impellers 10, 30, 50 can keep the thrust force below the predetermined allowable load limit L, A specific speed that covers the entire specific speed range R2 and the third specific speed range R3 can be realized. The user can choose the most suitable one among the three pumps 1, 2, 3 with three different types of impellers 10, 30, 50 based on the required specific speed.

FIG. 13 is a pump selection graph showing the first specific speed range R1, the second specific speed range R2, and the third specific speed range R3 by the pump head and discharge flow rate of the pumps 1, 2, and 3. FIG. Points a, b, and c shown in FIG. 13 indicate operating points of the three pumps 1, 2, and 3 having the same discharge flow rate. , correspond to the double star impeller 50, respectively.

The three pumps 1, 2, and 3 described above having the same discharge flow rate are an example, and the head and discharge flow rate are the first specific speed range R1, the second specific speed range R2, and the third ratio Three pumps with three different types of impellers 10, 30, 50 may have different discharge flow rates as long as they are within the speed range R3. That is, a pump with a circular impeller has an operating point within the first specific speed range R1, and a pump with a single star impeller has an operating point within the second specific speed range R2, A pump with a double star impeller is a pump with an operating point within the third specific speed range R3.

The user can select the optimum one among the three pumps 1, 2, 3 based on the required head and discharge flow rate. If the required specific speed, that is, the required discharge flow rate and head are within the first specific speed range R1, the second specific speed range R2, and the third specific speed range R3, the thrust force is applied to the bearings 15, 35. , 55 is less than the allowable load limit L. Therefore, an inexpensive pump can be provided to the user.

The specific speed required by the user may be covered only by the first specific speed range R1 and the second specific speed range R2, or by only the second specific speed range R2 and the third specific speed range R3. Therefore, in one embodiment, the pump group 100 may consist only of the pump 1 with the circular impeller 10 and the pump 2 with the single star impeller 30 . Alternatively, in other embodiments, pump group 100 may consist only of pump 2 with single star impeller 30 and pump 3 with double star impeller 50 .

FIG. 14 is a schematic diagram showing a pump selection device 81 that selects and displays one pump from the pump group 100 described above. This pump selection device 81 includes an input device 82 , a processing device 83 , a storage device 84 , a screen display device 85 and a printer 86 . The pump selection device 81 is composed of a dedicated computer, a general-purpose computer, a tablet computer, or the like.

Input device 82 includes a keyboard, a mouse, and the like. The user uses the input device 82 to input the required head and/or discharge flow rate to the pump selection device 81 . The input lift and/or discharge flow rate are stored in the storage device 84 . The processing device 83 includes a CPU (Central Processing Unit) or GPU (Graphic Processing Unit) that performs calculations according to programs stored in the storage device 84 . Storage device 84 includes primary storage (eg, random access memory) accessible by processing unit 83 and secondary storage (eg, hard disk drive or solid state drive) for storing data and programs.

The storage device 84 stores in advance a pump selection graph shown in FIG. 13 and a graph showing the relationship between specific speed and thrust load shown in FIG. Processor 83 selects the pump corresponding to the lift and/or discharge flow rate entered by the user. The selected pump is a pump that has an operating point within at least one of a first specific speed range R1, a second specific speed range R2, and a third specific speed range R3 shown in FIG. For example, if the user's required head and discharge flow rate are in the first specific speed range R1, the processor 83 selects a pump with a circular impeller. If the information entered by the user was only the lift, then processor 83 selects a plurality of pumps corresponding to that lift.

The pump selected by processor 83 is displayed on screen display 85 . The pump selection device 81 can also display the graph shown in FIG. 12 and the pump selection graph shown in FIG.

The above-described embodiments are described for the purpose of enabling a person having ordinary knowledge in the technical field to which the present invention belongs to implement the present invention. Various modifications of the above embodiments can be made by those skilled in the art, and the technical idea of the present invention can be applied to other embodiments. Accordingly, the present invention is not limited to the described embodiments, but is to be construed in its broadest scope in accordance with the technical spirit defined by the claims.

1, 2, 3 Pump 10 Circular impeller 11 Pump casing 12 Rotating shaft 15 Bearing 16 Bearing housing 17 Mechanical seal 21 Blade 22 Hole 24 Circular main plate 25 Fluid inlet 27 Circular side plate 30 Single star impeller 31 Pump casing 32 Rotation Shaft 35 Bearing 36 Bearing housing 37 Mechanical seal 41 Blade 42 Hole 44 Circular main plate 45 Fluid inlet 47 Star side plate 49 Recess 50 Double star impeller 51 Pump casing 52 Rotating shaft 55 Bearing 57 Mechanical seal 61 Blade 62 Hole 64 star-shaped main plate 65 fluid inlet 67 star-shaped side plate 69 depression 71 protrusion 81 pump selection device 82 input device 83 processing device 84 storage device 85 screen display device 86 printer 100 pump group

Claims (4)

A double star impeller used in a pump, comprising:
a plurality of wings;
a star-shaped main plate having a hole into which the rotating shaft of the pump is fitted;
having a star-shaped side plate with a fluid inlet,
The outer diameter of the main plate is smaller than the outer diameter of the side plate,
The main plate has a plurality of protrusions that are in contact with the plurality of blades, and the protrusions have a shape that protrudes outward in the radial direction of the double star impeller,
A double star impeller, wherein the plurality of protrusions are adjacent to each other. 2. The double star impeller of claim 1, wherein the area of the outer surface of the side plates is greater than the area of the outer surface of the main plate. The side plate has a plurality of recesses located between the plurality of blades, and the recesses have a shape recessed inward in the radial direction of the double star impeller. Double star impeller according to claim 1 or 2. The double star impeller according to any one of claims 1 to 3, wherein the double star impeller is a centrifugal impeller without balance holes.

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