JP2020063715A - Impeller used in pump - Google Patents

Abstract

To provide an impeller which can reduce thrust force.SOLUTION: A double-star type impeller 50 includes a plurality of blades 61, star-type main plate 64 having a hole 62 in which a rotation shaft 52 of a pump 3 is fitted, and a star-type side plate 67 having a fluid inlet 65. An outer diameter of the main plate 64 is smaller than an outer diameter of the side plate 67.SELECTED DRAWING: Figure 10

Description

  The present invention relates to an impeller used in a pump for transferring a liquid.

  Generally, the impeller used for a pump is a semi-open type impeller that does not have a side plate (also called a front shroud), or a full open type that does not have a side plate and has a smaller main plate (also called a back shroud). It is an impeller. However, these types of impellers have poor assemblability and poor pump performance. Therefore, a reverse-open type impeller having relatively good pump performance may be used for the pump. The reverse-open type impeller is an impeller having no main plate and wings fixed to the side plates.

US Pat. No. 5,605,444

  However, since a large thrust force toward the motor acts on this type of impeller, the pump needs to include a bearing having a large allowable load capable of receiving not only the radial force but also the thrust force. For example, angular ball bearings are generally expensive, and at least two angular ball bearings need to be arranged opposite to each other in order to receive thrust forces in both directions. This not only increases the overall cost of the pump, but also increases the size of the pump itself to build a robust bearing system. Furthermore, a device for cooling the bearing is required, which increases the cost of the pump.

  Therefore, the present invention provides an impeller that can reduce the thrust force.

In one aspect, a double star impeller used for a pump, comprising a plurality of blades, a star-shaped main plate having a hole into which a rotation axis of the pump is fitted, and a star-shaped main plate having a fluid inlet. There is provided a side plate, and 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 recessed inward in the radial direction of the double star impeller. The main plate includes a plurality of protrusions that are in contact with the plurality of blades, respectively, and the protrusions have a shape protruding outward in the radial direction of the double star impeller. .
In one aspect, the double star impeller is a centrifugal impeller having no balance hole.

In one aspect, a single star impeller used for a pump, wherein a plurality of blades, a circular main plate having a hole into which a rotating shaft of the pump is fitted, and a star-shaped side plate having a fluid inlet are provided. And a single star impeller in which 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 recessed inward in the radial direction of the single star impeller. ing.
In one aspect, the single star impeller is a centrifugal impeller having no balance hole.

In one aspect, a circular impeller used for a pump, comprising a plurality of blades, a circular main plate having a hole into which a rotating shaft of the pump is fitted, and a circular side plate having a fluid inlet, A circular impeller is provided in which an outer diameter of the main plate is smaller than an 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 circular impeller is a centrifugal impeller having no balance hole.

  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 of the liquid pushing the side plate toward the main plate and the force of the liquid pushing the main plate toward the side plate is small. As a result, the thrust force transmitted from the impeller to the bearing can be reduced. Further, according to the present invention, it is not necessary to provide a balance hole in the impeller, and it is possible to prevent a decrease in pump efficiency.

It is a schematic diagram which shows one Embodiment of the pump group containing three pumps. It is sectional drawing which shows the pump which has 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. It is sectional drawing which shows the pump which has a single star type impeller. It is the figure which looked at the single star impeller shown in FIG. 5 from the suction side. It is the figure seen from the discharge side of the single star impeller shown in FIG. It is sectional drawing which shows the pump which has a double star type impeller. It is the figure which looked at the double star type impeller shown in FIG. 8 from the suction side. It is the figure seen from the discharge side of the double star impeller shown in FIG. It is a schematic diagram of a circular impeller, a single star impeller, and a double star impeller, which were compared under the same discharge flow rate condition. It is a graph explaining the relationship between the specific force of three pumps which have a circular impeller, a single star impeller, and a double star impeller, respectively, and the thrust force applied to the bearing of each pump. FIG. 13 is a pump selection graph in which the first specific speed range, the second specific speed range, and the third specific speed range shown in FIG. 12 are represented by a pump head and a discharge flow rate. It is a schematic diagram which shows the pump selection apparatus which selects and displays one pump from a pump group.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic diagram showing an embodiment of a pump group 100 including a pump 1, a pump 2, and a pump 3. Each of these three pumps 1, 2, 3 comprises three different types of impellers and has different specific speeds. More specifically, the specific speed of the pump 1 is higher than the specific speed of the pump 2, and the specific speed of the pump 2 is higher than the specific speed of the pump 3.

  Each pump 1, 2, 3 included in the pump group 100 is used for the purpose of transferring a liquid. The user can select the most suitable one of the three pumps 1, 2, 3 based on the required specific speed. In the present 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 the three pumps 1, 2, and 3. It may be included, or in addition to the three pumps 1, 2 and 3, one or more pumps having different specific speeds may be further included.

  FIG. 2 is a sectional view showing the pump 1. The pump 1 of this embodiment is a single-stage centrifugal pump. The pump 1 includes a circular impeller 10, a pump casing 11 accommodating 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. The 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 rotary shaft 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 a function of sealing the gap between the rotary shaft 12 and the pump casing 11 while allowing the rotary 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 rotary shaft 12 is fixed to the circular impeller 10, and the circular impeller 10 and the rotary shaft 12 can rotate integrally. The other end of the rotary 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, the liquid is sucked into the circular impeller 10 through the suction port 11A. Velocity energy is applied to the liquid by the rotating circular impeller 10, and the velocity energy is converted into pressure when the liquid flows through the volute chamber 11C. The pressurized liquid is discharged from the discharge port 11B.

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

  As can be seen from FIGS. 2 and 3, the circular impeller 10 is a centrifugal impeller having no balance hole. Therefore, the circular impeller 10 can improve the pump efficiency. Further, since the circular impeller 10 does not have a balance hole, it is suitable for transferring a slurry containing particles. If the circular impeller 10 has a balance hole, when the slurry passes through the balance hole, the balance hole is worn, the balance hole gradually expands, and the pump efficiency decreases. Further, the slurry may block the balance hole, and in this 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 including the circular impeller 10 having no balance hole 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 24a of the main plate 24 is smaller than the area of the outer surface 27a of the side plate 27. The outermost ends 21 a of the plurality of blades 21 are on the outer peripheral edge 27 b of the side plate 27. The outer peripheral edge 24b of the main plate 24 is located inward of the outer peripheral edge 27b of the side plate 27 and the outermost ends 21a of the blades 21 in the radial direction. That is, as shown in FIG. 4, the blade 21 projects radially outward from the outer peripheral edge 24 b of the main plate 24.

  When the pump 1 including the circular impeller 10 is transferring liquid, the liquid pressure is applied to the outer surface 27a of the side plate 27 and the outer surface 24a of the main plate 24 of the circular impeller 10. 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 in the direction from the side plate 27 toward the main plate 24 is generated. This thrust force is transmitted by the rotating shaft 12 shown in FIG.

  The thrust force transmitted from the circular impeller 10 to the bearing 15 can change depending on 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. 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 predetermined so that the thrust force is less than the allowable load limit of the bearing 15. 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 make it unnecessary to use a bearing having a large allowable load in the pump 1.

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

  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 can rotate integrally. The other end of the rotary 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 given to the liquid by the rotating single star impeller 30, and the velocity energy is converted into pressure when the liquid flows through the volute chamber 31C. The pressurized liquid is discharged from the discharge port 31B.

  6 is a view of the single star impeller 30 shown in FIG. 5 as viewed from the suction side, and FIG. 7 is a view of the single star impeller 30 shown in FIG. 5 as viewed from the discharge side. The single star impeller 30 includes a plurality of blades 41, a circular main plate 44 having a hole 42 into which the rotary shaft 32 fits, and a star-shaped side plate 47 having a fluid inlet 45. The plurality of blades 41 are arranged at equal intervals around the hole 42 (that is, around the rotary shaft 32). The plurality of blades 41 are arranged between the side plate 47 and the main plate 44, and are fixed to both the side plate 47 and the main plate 44. As can be seen from FIGS. 6 and 7, the single star impeller 30 is a centrifugal impeller having no balance hole. Therefore, the single star impeller 30 is not only suitable for transferring the slurry, but also can improve the pump efficiency. The pump 2 provided 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 44a of the main plate 44 is smaller than the area of the outer surface 47a of the side plate 47. The outermost ends 41 a of the blades 41 are on the outer peripheral edge 47 b of the side plate 47. The outer peripheral edge 44b of the main plate 44 is located inward of the outer peripheral edge 47b of the side plate 47 and the outermost ends 41a of the blades 41 in the radial direction. That is, as shown in FIG. 7, the blade 41 projects radially outward from the outer peripheral edge 44 b of the main plate 44.

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

  The pump 2 with the single star impeller 30 has a lower specific speed than the pump 1 with the circular impeller 10. Generally, under the same discharge flow rate, the outer diameter of the impeller increases as the specific speed decreases. As a result, the thrust force transmitted from the impeller to the bearing becomes large. 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 recessed portions 49 located between the plurality of wings 41. Each recess 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 recesses 49 contribute to reduce the area of the outer surface 47a of the side plate 47. As described above, under the same discharge flow rate, the outer diameter of the impeller increases as the specific speed decreases. Therefore, in the present embodiment, the outer diameter of the single star impeller 30 is larger than the outer diameter of the circular impeller 10, but the outer peripheral edge 47b of the side plate 47 has the plurality of recesses 49 formed therein. The pressure receiving area of the outer surface 47a 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 may change depending on 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. 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 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. is there. The single star impeller 30 having the star-shaped side plate 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. The pump 3 of this embodiment is a single-stage centrifugal pump. This pump 3 includes a double star impeller 50, a pump casing 51 accommodating the double star impeller 50, a rotary shaft 52 to which the double star impeller 50 is fixed, and a rotary shaft 52. It has two bearings 55 for supporting. The two bearings 55 are held by a bearing housing 56 fixed to the pump casing 51. The two bearings 55 are arranged apart from each other along the rotating shaft 52. Each bearing 55 is composed of a ball bearing. A mechanical seal 57 as a shaft sealing device is arranged on the back side of the double star impeller 50. The mechanical seal 57 has a function of sealing the gap between the rotary shaft 52 and the pump casing 51 while allowing the rotary 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 rotary shaft 52 is fixed to the double star impeller 50, and the double star impeller 50 and the rotary shaft 52 can rotate integrally. The other end of the rotary shaft 52 is connected to a prime mover (for example, an electric motor) not shown. When the double star impeller 50 and the rotary 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 applied to the liquid by the rotating double star impeller 50, and the velocity energy is converted into pressure when the liquid flows through the volute chamber 51C. The pressurized liquid is discharged from the discharge port 51B.

  9 is a view of the double star impeller 50 shown in FIG. 8 viewed from the suction side, and FIG. 10 is a view of the double star impeller 50 shown in FIG. 8 viewed from the discharge side. . The double star impeller 50 includes a plurality of blades 61, a star-shaped main plate 64 having a hole 62 into which the rotating shaft 52 fits, and a star-shaped side plate 67 having a fluid inlet 65. The plurality of blades 61 are arranged around the hole 62 (that is, around the rotating shaft 52) at equal intervals. The plurality of blades 61 are arranged between the side plate 67 and the main plate 64, and are fixed to both the side plate 67 and the main plate 64. As can be seen from FIGS. 9 and 10, the double star impeller 50 is a centrifugal impeller having no balance hole. Therefore, the double star impeller 50 is not only suitable for slurry transfer, but can also improve pump efficiency. The pump 3 equipped 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 64a of the main plate 64 is smaller than the area of the outer surface 67a of the side plate 67. The outermost ends 61 a of the plurality of blades 61 are on the outer peripheral edge 67 b of the side plate 67. The outer peripheral edge 64b of the main plate 64 is located inward of the outer peripheral edge 67b of the side plate 67 and the outermost ends 61a of the blades 61 in the radial direction. That is, as shown in FIG. 10, the blade 61 projects radially outward from the outer peripheral edge 64 b of the main plate 64.

  When the pump 3 equipped with the double star impeller 50 is transferring liquid, the liquid pressure is applied to the outer surface 67 a of the side plate 67 and the outer surface 64 a of the main plate 64 of the double star impeller 50. 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 transmitted by the rotating shaft 52 shown in FIG.

  The pump 3 with the double star impeller 50 has a lower specific speed than the pump 2 with the single star impeller 30. As described above, generally, under the same discharge flow rate, the outer diameter of the impeller increases as the specific speed decreases. As a result, the thrust force transmitted from the impeller to the bearing becomes large. 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 recessed portions 69 located between the plurality of wings 61. Each recess 69 is located between two adjacent blades 61, and has a shape recessed inward in the radial direction of the double star impeller 50. These recesses 69 contribute to reducing the area of the outer surface 67a of the side plate 67. That is, since the plurality of recesses 69 are formed on 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, and as a result, the thrust force transmitted from the double star impeller 50 to the bearing 55 is reduced. Is reduced. However, since the outer diameter itself of the side plate 67 is large, it is difficult to make the thrust force less than the allowable load limit of the bearing 55 only by forming the recess 69.

  Therefore, in order to increase the force with which the liquid pushes the outer surface 64a of the main plate 64, the main plate 64 also has a star shape. More specifically, the star-shaped main plate 64 has a plurality of protrusions 71 that are in contact with the plurality of wings 61, respectively. Each protrusion 71 protrudes outward in the radial direction of the double star impeller 50. Unlike the recesses 69 formed on the side plates 67, these protrusions 71 contribute to increasing the area of the outer surface 64a of the main plate 64. 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 protruding portion 71 to increase the pressure receiving area of the main plate 64. Most of the force that the liquid pushes the outer surface 67 a of the side plate 67 is canceled by the force that the liquid pushes the main plate 64. As a result, the thrust force applied from the double star impeller 50 to the bearing 55 can be less than the allowable load limit of the bearing 55.

  The thrust force transmitted from the double star impeller 50 to the bearing 55 may change depending on the ratio of 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. 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 predetermined so that the thrust force is less than the allowable load limit of the bearing 55. 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 having the star-shaped side plate 67 and the star-shaped main plate 64 can reduce the thrust force applied to the bearing 55 while achieving a low specific speed.

  A pump group 100 including at least a pump 1 having a circular impeller 10, a pump 2 having a single star impeller 30 and a pump 3 having a double star impeller 50 has a thrust force bearing 15, 35, 55. It is possible to cover a wide range of specific speeds while keeping the allowable load limit below.

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

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

  The thrust forces Δ1, Δ2, Δ3 are received by the bearings 15, 35, 55, respectively. The thrust forces Δ1, Δ2 and Δ3 are all less than the allowable load limit of the bearings 15, 35 and 55. In other words, the side plates 27 and the main plate 24 of the circular impeller 10 and the side plates 47 and the main plate 44 of the single star impeller 30 are set so that the thrust forces Δ1, Δ2 and Δ3 are less than the allowable load limits of the bearings 15, 35 and 55. The shapes and sizes of the side plate 67 and the main plate 64 of the double star impeller 50 are determined.

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

  In the first specific speed range R1, the pump 1 including the circular impeller 10 is used. As described with reference to FIGS. 3 and 4, in the circular impeller 10, both the side plate 27 and the main plate 24 are circular. The circular side plate 27 and the circular main plate 24 have a size such that the pump 1 can 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, before the thrust force exceeds the allowable load limit L of the bearing 15, the pump 1 including the circular impeller 10 is switched to the pump 2 including the single star impeller 30. In the single star impeller 30, the side plates 47 are star-shaped and the main plate 44 is circular, as described with reference to FIGS. 6 and 7. The star-shaped side plate 47 and the circular main plate 44 have such a size and shape that the pump 2 can 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, before the thrust force exceeds the allowable load limit L of the bearing 35, the pump 2 including the single star impeller 30 is switched to the pump 3 including the double star impeller 50. In the double star impeller 50, both the side plate 67 and the main plate 64 are star-shaped, as described with reference to FIGS. 9 and 10. The star-shaped side plate 67 and the main plate 64 have such a size and shape that the pump 3 can achieve a specific speed within the third specific speed range R3.

  As described above, the pumps 1, 2, and 3 including the three different types of impellers 10, 30, and 50 suppress the thrust force to be less than the predetermined allowable load limit L, and the first specific speed range R1 and the second specific speed range R1. A specific speed that covers the entire specific speed range R2 and the third specific speed range R3 can be realized. The user can select the optimum one from the three pumps 1, 2, 3 with three different types of impellers 10, 30, 50, based on the specific speed required.

  FIG. 13 is a pump selection graph in which the first specific speed range R1, the second specific speed range R2, and the third specific speed range R3 are represented by the lift and discharge flow rates of the pumps 1, 2, and 3. Points a, b, and c shown in FIG. 13 indicate operating points of three pumps 1, 2 and 3 having the same discharge flow rate, and the circular impeller 10 and the single star impeller 30 shown in FIG. , And the double star impeller 50, respectively.

  The above-mentioned three pumps 1, 2 and 3 having the same discharge flow rate are examples, and the lift and discharge flow rates are the first specific speed range R1, the second specific speed range R2, and the third ratio shown in FIG. As long as it is within the speed range R3, the three pumps with the three different types of impellers 10, 30, 50 may have different delivery flow rates. That is, a pump having a circular impeller is a pump having an operating point in the first specific speed range R1, and a pump having a single star impeller is a pump having an operating point in the second specific speed range R2. A pump having a double star impeller is a pump having an operating point in the third specific speed range R3.

  The user can select the optimum one from 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 is within the first specific speed range R1, the second specific speed range R2, and the third specific speed range R3, the thrust force is the bearing 15, 35. , 55 is less than the allowable load limit L. Therefore, an inexpensive pump can be provided to the user.

  It may be possible that the specific speed required by the user can be covered only by the first specific speed range R1 and the second specific speed range R2, or only by the second specific speed range R2 and the third specific speed range R3. Therefore, in one embodiment, the pump group 100 may include only the pump 1 including the circular impeller 10 and the pump 2 including the single star impeller 30. Alternatively, in another embodiment, the pump group 100 may include only the pump 2 including the single star impeller 30 and the pump 3 including the 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. The pump selection device 81 includes an input device 82, a processing device 83, a storage device 84, a screen display 85, and a printing machine 86. The pump selection device 81 is composed of a dedicated computer, a general-purpose computer, a tablet computer, or the like.

  The input device 82 includes a keyboard and a mouse. 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 head and / or discharge flow rate is stored in the storage device 84. The processing device 83 includes a CPU (central processing unit) or a GPU (graphic processing unit) that performs an operation according to a program stored in the storage device 84. The storage device 84 includes a main storage device (for example, a random access memory) accessible by the processing device 83 and an auxiliary storage device (for example, a hard disk drive or a solid state drive) for storing data and programs.

  The storage device 84 stores therein beforehand a pump selection graph shown in FIG. 13 and a graph showing the relationship between the specific speed and the thrust load shown in FIG. The processing device 83 selects a pump corresponding to the head and / or the discharge flow rate input by the user. The selected pump is a pump having an operating point in at least one of the first specific speed range R1, the second specific speed range R2, and the third specific speed range R3 shown in FIG. For example, if the head and discharge flow rate required by the user are within the first specific speed range R1, the processing device 83 selects a pump having a circular impeller. When the information input by the user is only the head, the processing device 83 selects a plurality of pumps corresponding to the head.

  The pump selected by the processing device 83 is displayed on the 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. 13 on the screen display 85.

  The above-described embodiment is 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-described embodiment can be naturally made by those skilled in the art, and the technical idea of the present invention can be applied to other embodiments. Therefore, the present invention is not limited to the described embodiments, but is to be construed in its broadest scope according to the technical idea 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 Dimple 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 recess 71 protrusion 81 pump selection device 82 input device 83 processing device 84 storage device 85 screen display 86 printing machine 100 pump group

Claims (11)

A double star impeller used for pumps,
Multiple wings,
A star-shaped main plate having a hole into which the rotary shaft of the pump is fitted;
With a star-shaped side plate having a fluid inlet,
A double star impeller in which the outer diameter of the main plate is smaller than the outer diameter of the side plate.   The double star impeller according to claim 1, wherein an area of an outer surface of the side plate is larger than an area of an outer surface of the main plate. The side plate has a plurality of recesses located between the plurality of blades, the recesses have a shape recessed inward in the radial direction of the double star impeller,
The main plate includes a plurality of protrusions respectively in contact with the plurality of blades, and the protrusions have a shape protruding outward in a radial direction of the double star impeller. Or the double star impeller according to 2.   The double star impeller according to any one of claims 1 to 3, wherein the double star impeller is a centrifugal impeller having no balance hole. A single star impeller used for a pump,
Multiple wings,
A circular main plate having a hole into which the rotary shaft of the pump is fitted;
With a star-shaped side plate having a fluid inlet,
A single star impeller, in which the outer diameter of the main plate is smaller than the outer diameter of the side plate.   The single star impeller according to claim 5, wherein an area of an outer surface of the side plate is larger than an area of an outer surface of the main plate.   The side plate has a plurality of recesses located between the plurality of blades, the recesses have a shape recessed inward in the radial direction of the single star impeller, Item 7. A single star impeller according to item 5 or 6.   The single star impeller according to any one of claims 5 to 7, wherein the single star impeller is a centrifugal impeller having no balance hole. A circular impeller used for a pump,
Multiple wings,
A circular main plate having a hole into which the rotary shaft of the pump is fitted;
A circular side plate having a fluid inlet,
A circular impeller in which the outer diameter of the main plate is smaller than the outer diameter of the side plate.   The circular impeller according to claim 9, wherein an area of an outer surface of the side plate is larger than an area of an outer surface of the main plate.   The circular impeller according to claim 9 or 10, wherein the circular impeller is a centrifugal impeller having no balance hole.

Images