JP2015014251A - Pump blade for submersible pump and submersible pump including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pump blade for a submersible pump that can cancel or reduce a radial load.SOLUTION: A pump blade for a non-clog type submersible pump comprises: a nearly cylindrical body part; a suction port 15 provided at the center of a lower end surface of the body part; discharge ports 17A and 17B opened in a side surface of the body part; and flow passages 13A and 13B that allow the suction port to communicate with the discharge ports inside the body part. The number of the flow passages 13A and 13B is two or more, and the dimensions, shapes, and positions of the flow passages are set so as to reduce fluid imbalance with respect to a rotation axis C.

Description

  The present invention relates to a pump blade for a submersible pump, and more particularly to a pump blade for a submersible pump used for sewage waste and a submersible pump equipped with the same.

  Conventionally, there has been a submersible pump for wastewater filth as shown in FIG. In this submersible pump, pump blades 111 as shown in FIG. 9 are used (see Patent Document 1). The pump blade 111 has a suction port 129 formed at one end and a discharge port 134 formed laterally on the other end side, and a spiral flow path 135 that connects the suction port 129 and the discharge port 134 is defined inside. This is a substantially cylindrical pump blade 111 formed. Further, a flange portion 140 that protrudes outward along the outer peripheral surface from the suction port side portion of the outer peripheral surface of the pump blade 111 from the suction port side and partitions the suction port side and the discharge port side is provided. Yes.

  The pump blade 111 is accommodated in a pump casing 112 and is connected to a sealed submersible motor 113 for rotationally driving the pump blade 111. The underwater motor 113 includes a motor 116 including a stator 114 and a rotor 115, and a motor casing 117 that covers the motor 116. A drive shaft 118 extending in the vertical direction is provided at the center of the rotor 115. The upper end portion of the drive shaft 118 and the middle portion on the slightly lower side are rotatably supported by bearings 119 and 120, respectively. The pump blade 111 is connected to the lower end portion of the drive shaft 118.

  Inside the pump casing 112 is formed a pump chamber 126 defined by an inner wall 125 having a semicircular cross section. The discharge part 138 of the pump blade 111 is accommodated in the pump chamber 126. A suction portion 121 that protrudes downward is formed in the lower portion of the pump casing 112. A suction port 122 that opens downward is formed in the suction part 121. On the side of the pump casing 112, a discharge portion 123 protruding sideways is formed. The discharge part 123 is formed with a discharge port 124 that opens to the side.

  The pump blade 111 is provided with a suction part 127 and a discharge part 128 in order from the lower side to the upper side in the axial direction. The suction part 127 and the discharge part 128 are both formed in a substantially cylindrical shape, and the discharge part 128 is configured to have a larger diameter than the suction part 127. The discharge part 128 and the suction part 127 are partitioned by a flange part 140 protruding outward from the outer peripheral surface of the pump blade 11. A suction port 129 that opens downward is provided at the lower end of the suction portion 127 of the pump blade 111. The upper side of the discharge part 128 is covered with an upper end wall. That is, the upper side of the pump blade 111 is sealed by the upper end wall. A hole into which the tip of the drive shaft 118 is inserted is formed at the center of the upper end wall, and a peripheral portion of the hole constitutes an attachment portion 131 for attaching the drive shaft 118. Reference numeral 137 represents a secondary flow path, and reference numeral 138 represents a secondary blade.

Japanese Patent No. 4713066

However, the above prior art has problems that cannot be avoided. That is, in the conventional pump blade, a large radial load is generated when rotating. This point will be described in detail below.

  In the pump blade 111 according to the invention disclosed in Patent Document 1, the number of flow paths from the suction port 129 to the discharge port 134 is one. That is, sewage filth is sucked from the suction port 129 that is coaxial with the drive shaft 118 and opens downward, and the sewage filth is discharged from the discharge port 134 through one spiral channel. Yes. Here, since the part in which the spiral flow path is formed is a space, there is no weight. On the other hand, the part which forms the wall of the pump blade | wing 111 has weight. For this reason, with respect to the axis (rotation center) of the drive shaft 118, the weight of the pump blade 111 is greatly deviated along the circumferential direction. When such a pump blade 111 rotates, the deviation of the weight of the fluid with respect to the rotation center also increases, and a radial load is likely to be generated.

  In consideration of the above problems, it is also conceivable to add a weight that cancels the radial load after balancing the weight balance (dynamic balance) of the pump blades. That is, after removing the balance of the wall of the pump blade so as to eliminate the unbalance of the weight along the circumferential direction of the pump blade, A weight that cancels the load is applied in the opposite direction. However, even if the device is used, there is a limit. This is because sewage filth flows in the spiral flow path of the pump blade, and the weight of the sewage filth itself is added to the pump blade. I can't. Furthermore, even if the weight of the sewage filth itself is taken into account in advance, the mixing ratio of the sewage sewage that flows from time to time also changes, so in conventional pump blades with one spiral channel, the radial load can be eliminated or reduced Impossible. In view of the above problems, it is desirable that the fluid balance is balanced.

  Here, the above-described dynamic balance is defined as a deviation of the center of gravity and the center of moment with respect to the rotation axis when the impeller is rotated in the air. The dynamic balance can be removed by the correction work such as the above-described meat removal. The fluid balance refers to the balance when the fluid is flowing in the flow path with the rotation of the pump blade. Even if the above-mentioned dynamic balance is optimal (weight unbalance is 0), when the pump blade is rotated in water, the water (sewage waste) region in the pump blade is biased with respect to the rotation axis. For this reason, fluid imbalance arises and force (this is called radial load) acts on a pump blade through wall pressure. Since large radial load fluctuations can cause vibrations, some devices have been devised to add weights to offset them. In this regard, in the multi-channel as in the present invention, the mass distribution in the water region is less likely to be non-axisymmetric as compared with the single channel, so that the radial load can be greatly reduced. In view of the above points, specific means for solving the problems are as follows.

  The present invention has been made in view of the above problems, and in the first means, a substantially cylindrical main body portion, a suction port provided at the center of the lower end surface of the main body portion, and an opening on the side surface of the main body portion. A non-clog type pump blade for a submersible pump comprising a discharge port and a flow channel communicating from the suction port to the discharge port inside the main body, and there are a plurality of flow channels. The configuration is such that the size, shape and position of the flow path are set so as to reduce the fluid imbalance with respect to the rotation axis.

  By adopting such a configuration, the sewage filth sucked from the suction port flows in each flow path. At this time, since the flow path is set so as to reduce the fluid imbalance, it is difficult for the fluid imbalance to occur with respect to the rotation axis, and the generation of the radial load accompanying the rotation of the pump blade can be significantly suppressed.

  Further, the second means employs a configuration in which the number of flow paths is two or more. By adopting such a configuration, discharge of sewage filth during one rotation of the pump blade is distributed a plurality of times, and pressure fluctuation during discharge is suppressed.

  Moreover, in the 3rd means, the flow path has taken the structure that a cross-sectional area changes between a suction inlet and a discharge outlet. In the pump blade according to the present invention, when sewage filth is separated from the surface of the flow path near the discharge port, the sewage filth cannot be sucked from the suction port. For this reason, a cross-sectional area changes with places so that the pressure more than predetermined may be maintained.

  Moreover, in the 4th means, the flow path has taken the structure that a cross-sectional shape changes between a suction inlet and a discharge outlet. In the fifth means, the cross-sectional shape of the flow path is changed from a circular shape to a substantially rectangular shape or an elliptical shape from the suction port toward the discharge port. The suction port is circular, and the upstream portion of the flow path is also circular, whereas the outer peripheral surface of the pump blade is close to the shape of the outer peripheral surface of the cylinder. For this reason, in order to ensure a constant cross-sectional area, it is necessary to change the cross-sectional shape near the discharge port.

  Moreover, in the 6th means, the said flow path has taken the structure that the inner wall surface is formed in the continuous curved surface. By adopting such a configuration, the foreign matter in the sewage filth flows smoothly through the flow path, and the occurrence of clogging by the foreign matter can be prevented.

  In the seventh means, the inner wall in the vicinity of the branch portion of at least two flow paths has a different surface roughness. Under such a configuration, a long fibrous foreign matter may flow in two flow paths at a branch portion near the suction port. However, if the surface roughness is different between the flow paths, the frictional resistance on the flow path side having a smooth surface is low, and there is a high possibility that foreign matter flows on that side.

  In the eighth means, all the flow paths have the same size and shape and are arranged at equiangular intervals with respect to the rotation axis. By adopting the configuration as described above, the sewage filth sucked from the suction port flows in each flow path. At this time, since each flow path has the same size and shape and is arranged at an equiangular interval with respect to the rotation axis, there is no weight imbalance with respect to the rotation axis, and the radial load associated with the rotation of the impeller is not generated. Occurrence can be minimized.

  Further, a submersible pump comprising the pump blade according to any one of means 1 to 8, a pump casing for housing the pump blade, and a motor for driving the pump blade. Adopted. By adopting the above-described configuration, when assembled and operated as a pump, a pump with excellent fluid balance is realized, and problems such as noise and vibration do not occur.

According to the present invention, by taking the above-described means, the following effects can be obtained as an example.
1. Since the fluid balance of the pump blade can be taken with respect to the rotation axis, the average value of the radial load during operation can be reduced.
2. With the reduction of the radial load described above, noise and vibration during operation are reduced. Moreover, it is possible to change a bearing to a thing with a small capacity | capacitance, and even when using the conventional bearing as it is, the rated rotation speed of a pump blade can be increased.
3. Moreover, since there are a plurality of discharge ports and the discharge of sewage filth during one rotation of the pump blade is distributed multiple times, fluctuations in the discharge pressure are reduced.
4). The suction flow path in the vicinity of the suction port is a straight flow path that coincides with the rotation axis, so that the flow path length at the inlet portion is shortened, the flow smoothly flows in, loss is reduced, and hydraulic efficiency is improved. Improvement can be expected.

It is a figure which shows one flow path, FIG. 1 (A) is the perspective view which showed the shape of the flow path, and FIG. 1 (B) is a top view. It is a figure which shows the two flow paths used for the pump blade | wing which concerns on one Embodiment of this invention, FIG. 2 (A) is the perspective view which showed the shape of the flow path, FIG.2 (B) is a plane. FIG. It is a figure of a pump blade provided with a channel indicated in Drawing 2, Drawing 3 (A) is a perspective view seen from the suction mouth side, and Drawing 3 (B) is a side view. FIG. 4 is a view of the pump blade disclosed in FIG. 3, FIG. 4 (A) is a plan view, FIG. 4 (B) is a side view, and FIG. 4 (C) is a bottom view (suction port side). FIG. 5A is a cross-sectional view of a pump blade desired to be disclosed in FIG. 4, FIG. 5A is a cross-sectional view taken along line 5A-5A in FIG. 4A, and FIG. 5B is 5B-5B in FIG. It is sectional drawing in a line. It is a figure which shows the three flow paths used for the pump blade | wing which concerns on the 2nd Embodiment of this invention, FIG. 6 (A) is the perspective view which showed the shape of the flow path, FIG. 6 (B) Is a plan view. It is sectional drawing of a pump blade | wing provided with the flow path disclosed in FIG. FIG. 8A is a cross-sectional view showing pump blades when the size and shape of each flow path are different. FIG. 8A is a combination of one thin flow path and two thick flow paths, and FIG. This is a case where the angular intervals of the respective flow paths are different. It is sectional drawing which shows the structural example of the submersible pump provided with the pump blade | wing concerning one Embodiment of this invention. It is a side view which shows the conventional pump blade | wing. It is sectional drawing which shows a submersible pump provided with the pump blade disclosed in FIG.

  Next, a pump blade according to an embodiment of the present invention will be described with reference to FIGS.

[overall structure]
The pump blade according to the present embodiment includes a plurality of flow paths that allow the suction port coaxial with the rotation axis to communicate with the discharge port on the outer peripheral portion, and the flow paths are arranged in a logical sum at equal angular intervals with respect to the rotation axis. . The number of flow paths is not particularly limited, but those shown in FIGS. 3 to 5 are embodiments with two flow paths, and those shown in FIGS. 6 to 8 have three flow paths. It is an embodiment. The flow path is formed in a curved shape between the suction port and the discharge port. This pump blade is manufactured by casting as an example. However, other metals or non-metallic materials can be used as long as strength and corrosion resistance are ensured.

[Flow path]
FIG. 1 (A) is an image produced by computer graphics showing the flow path 3 used in the pump blade. When the shape of the flow path 3 is described from the suction port 5 toward the discharge port 7, the flow path is coaxial with the rotation axis C in the vicinity of the suction port 5. That is, the central axis of the flow path 3 in the vicinity of the suction port 5 is parallel to and coincides with the rotation axis C. On the downstream side, the central axis of the flow path 3 goes downward in the radial direction with respect to the rotation axis C while proceeding downward. The transition portion from the rotational axis direction to the radially outer side is formed by a continuous curve.

Furthermore, the central axis of the flow path 3 is also directed in the circumferential direction with respect to the rotation axis C while being directed radially outward. For this reason, the center axis of the flow path 3 goes outward in a spiral shape by combining the radially outer component and the circumferential component. The cross-sectional shape of the flow path 3 is a perfect circle in the vicinity of the suction port 5, but is a rectangle in the vicinity of the discharge port 7. For this reason, the transition region from the suction port 5 toward the discharge port 7 continuously changes so that the circle gradually becomes a rectangle. However, even if it is a rectangle, the corner portion is not a complete right-angle surface, but is formed by a curved surface with a small radius of curvature. This is to prevent foreign matters from clogging the corners.

  In FIG. 1A, the theoretical shape of the flow path 3 is shown, but when actually applied to the pump blade, the outer edge of the pump blade is circular with the rotation axis C as the center. Specifically, the ellipse shown in FIG. 1A defines the outer edge of the pump blade. For this reason, the actual flow path 3 formed in the pump blade has such a shape that the discharge port 7 is formed over a wide angular range, as shown in FIG. The above is the shape of the flow path 3 used for the pump blades, but this only explains the case where there is only one flow path 3. As described below, this embodiment is characterized by combining two flow paths, and a specific example thereof will be described.

  In FIG. 2A, two flow paths 13A and 13B are provided, and these flow paths 13A and 13B are configured by taking a logical sum with reference to the rotation axis C (suction port). . Each flow path 13A, 13B has completely the same size and shape, and is arranged at a point-symmetrical position with respect to the central axis C. In other words, the flow path 3 of FIG. 1 is rotationally copied and arranged at equiangular intervals. Therefore, as shown in FIG. 2 (B), the regions where the flow paths 13A and 13B are directed radially outward from the suction port 15 extend in directions (opposite directions) that are 180 ° apart from each other. Here, the logical sum means that the two flow paths are simply combined with the suction port in common.

  FIG. 2B is a diagram showing the actual flow paths 13A and 13B by the outer edges (indicated by dotted lines) of the pump blades, as in FIG. 1B. As shown in this figure, each of the flow paths 13A and 13B is completely point-symmetric with respect to the rotation axis C, and forms a generally S-shaped flow path as a whole. In the vicinity of the outer edge of the pump blade, discharge ports 17A and 17B are formed over a wide angular range, as in the example of FIG.

  FIG. 3 is a diagram in which the pump blade 11 according to the present embodiment is produced by computer graphics. In particular, FIG. 3 (A) is a view seen obliquely from the suction port 15 side, and FIG. 3 (B) is a view seen from the side. The flow paths formed inside the pump blade 11 shown in this figure are the flow paths 13A and 13B shown in FIG. As apparent from FIG. 3B, the cross-sectional shape of the flow path is close to a circle on the right side (upstream side) of the rotation axis C, and forms a part of a rectangle on the left side (downstream side) of the rotation axis. It has become a shape.

  FIG. 4 shows the pump blade 11 of the present embodiment, FIG. 4 (A) is a top view, FIG. 4 (B) is a side view, and FIG. 4 (C) is a bottom view. As shown in FIGS. 4 (A) and 4 (B), a cylindrical hub 14 is formed in the region of the central axis C, and a drive shaft (not shown) of a drive motor is provided on the hub 14. It is supposed to be inserted. The pump blade 11 rotates at a rotational speed of about 1500 rpm, for example. However, if the efficiency is improved, it can be rotated at a rotational speed lower than 1500 rpm or higher.

  FIG. 5A is a cross-sectional view taken along line 5A-5A in FIG. As shown in this figure, the pump blade 11 is formed with a suction port 15 that opens on one side of the central axis C, and sewage filth is sucked as the pump blade 11 rotates. . The sewage filth is transferred from the suction port 15 to the outside in the circumferential direction along the flow paths 13A and 13B, and finally discharged from the discharge ports 17A and 17B. As shown in the figure, an opening is also formed on the other end side of the central axis C. However, since the drive shaft is inserted as described above, sewage filth does not leak from this opening.

  FIG. 5B is a cross-sectional view taken along line 5B-5B in FIG. As shown in this figure, the flow paths 13A and 13B connected from the suction port 15 extend outward in the radial direction in a spiral shape, and form discharge ports 17A and 17B at the outer edge portion of the pump blade 11. For this reason, the part other than the flow path is a wall part constituting the pump blade 11. As is apparent from the drawing, the discharge ports 17A and 17B of the present embodiment are formed in an angle range of about 180 ° with respect to the central axis C. This is based on the basic idea that there are two flow paths 13A and 13B and that the discharge ports 17A and 17B are formed over as wide an angular range as possible to improve efficiency. In FIG. 5B, the pump casing 16 is also shown for convenience of explanation. The relationship between the pump blade 11 and the pump casing 16 will be described later.

  The suction port 15 is cylindrical and opens so as to be coaxial with the rotation axis C. For this reason, one suction port 15 which is substantially common is obtained by logical sum. When the suction port 15 is actually installed in a pump, the suction port 15 is arranged to open downward. The inner diameter of the suction port 15 is set based on the size of the solid matter contained in the sewage filth handled by the pump blade 11.

[Flow path branching section]
As shown in FIG. 5, the flow paths 13 </ b> A and 13 </ b> B branch from one suction port 15 into two flow paths as described above. The flow paths 13A and 13B have substantially the same cross-sectional area from the vicinity of the suction port 15 to the branch portion. On the other hand, the cross-sectional area gradually decreases from the branch portion toward the downstream side. This is because, if the cross-sectional areas of the flow paths 13A and 13B after branching are equal to the cross-sectional area of the suction port 15, the total area is doubled and the pressure of the sewage filth is reduced. This is because a sewage detachment phenomenon from the inner surfaces of the paths 13A and 13B occurs. If such a peeling phenomenon occurs, it is conceivable that the efficiency of the pump is lowered, and in some cases, the sewage filth cannot be sucked from the suction port 15. For this reason, the cross-sectional area of the flow paths 13A and 13B after branching is made smaller than the cross-sectional area of the suction port 15 as described above.

  The reduction ratio of the cross-sectional areas of the flow paths 13A and 13B after branching is variously changed depending on parameters such as the nature of the sewage filth to be handled and the rotational speed of the pump blade 11. For example, when the viscosity of sewage filth is high, the peeling phenomenon is unlikely to occur, and therefore the reduction rate of the cross-sectional area may be reduced. Further, when the rotational speed of the pump blade 11 is high, a peeling phenomenon is likely to occur, so it is desirable to increase the reduction ratio of the cross-sectional area. Regarding the specific reduction ratio of the cross-sectional area, for example, when the cross-sectional area of the suction port 15 is 1, the cross-sectional area of the flow path after branching is about 0.55 (when there are two flow paths). .

  Further, the inner wall surfaces of the flow paths 13A and 13B in the vicinity of the branch portion are formed so that the surface roughness is different from each other. This is a countermeasure when a fibrous object (long string-like object) exists in the sewage filth. For example, it is assumed that a fibrous object having a length of about several tens of centimeters exists in sewage filth. In this case, it is conceivable that both ends of the fibrous object flow separately into the two flow paths 13A and 13B. When such a state occurs, the fibrous object sticks to the branch portion and stays.

On the other hand, since the surface roughness of each of the flow paths 13A and 13B in the vicinity of the branch portion is different, the fibrous object can be smoothly flowed into the one flow path 13A or 13B. That is, the inner surface of one channel 13A is smoothed, and the inner surface of the other channel 13B is rough (for example, as cast). In such a case, the frictional resistance of the fibrous object is small on the smooth inner surface, and conversely, the friction coefficient is increased on the rough inner surface. Such a friction coefficient imbalance causes the fibrous object to flow toward the flow path having a smooth inner surface. Thus, the problem which may arise by making the flow path 13A, 13B into two by changing surface roughness dare can be solved.

[Operation of pump blade]
Next, based on FIG. 5 (B), the effect | action of the pump blade | wing 11 which concerns on this embodiment is demonstrated. The pump blade 11 rotates clockwise in FIG. At this time, centrifugal force associated with rotation acts on the sewage filth present in the (first) flow path 13A of the pump blade 11. For this reason, the sewage filth tends to move toward the radially outer side of the pump blade 11. When the discharge port 17 </ b> A of the pump blade 11 faces the discharge port 18 of the pump casing 16, sewage filth is sent out of the pump via the discharge port 17 </ b> A and the discharge port 18.

  When the pump blade 11 further rotates clockwise, the next discharge port 17B faces the discharge port 18 of the pump casing 16. The centrifugal force accompanying the rotation also acts on the sewage filth present in the (second) flow path 13B of the pump blade 11. For this reason, similarly to the above, sewage filth is sent out of the pump via the discharge port 17B and the discharge port 18. This means that sewage waste is discharged twice while the pump blade 11 rotates once. If the amount of discharged sewage filth is the same as that of a conventional pump blade having only one flow path, the discharge of sewage filth is distributed twice, so that the amount discharged per time is half. Become. For this reason, the pulsation (pressure fluctuation) at the time of discharge of sewage filth is suppressed low.

  As described above, when sewage filth is discharged from the pump blade 11, a pressure drop occurs in the flow paths 13A and 13B. As an effect of this pressure drop, sewage filth is sucked from the suction port 15. For this reason, as described above, the cross-sectional areas of the flow paths 13A and 13B are defined so that sewage filth is not separated from the inner surfaces of the flow paths 13A and 13B in the vicinity of the discharge ports 17A and 17B. The cross-sectional areas of the flow paths 13A and 13B may be gradually changed from the suction port 15 toward the discharge ports 17A and 17B. The predetermined section has a constant cross-sectional area and the other sections have different sizes. It may have a constant cross-sectional area.

  Further, in the flow paths 13A and 13B of the present embodiment, the cross-sectional shape changes from a circular shape to a rectangular shape between the suction port 15 and the discharge ports 17A and 17B. However, these cross-sectional shapes are merely examples. For example, the shape may be circular → transition region → elliptical in order from the suction port 15 to the discharge ports 17A and 17B, or a combination of circular → transition region → elliptical → transition region → rectangle. Moreover, although the rectangle of this embodiment is a square, you may make it a rectangular cross section.

  Moreover, as for the flow paths 13A and 13B, all the inner wall surfaces are formed in the continuous curved surface. This is to prevent clogging of foreign matters in the flow paths 13A and 13B. In the present embodiment, the cross-sectional shapes of the flow paths 13A and 13B are rectangular in the vicinity of the discharge ports 17A and 17B. However, the corners of the cross section are not completely right angles but connected by a continuous curved surface. In addition, the shape of the longitudinal axis of the flow paths 13A and 13B (the line connecting the cross-sectional centers of the discharge ports 17A and 17B from the suction port 15) is also continuous. For this reason, it is prevented that it catches in flow path 13A, 13B in the process in which sewage filth flows.

  FIG.6 and FIG.7 is a figure explaining the pump blade | wing 21 which concerns on 2nd Embodiment provided with three flow paths. In particular. 6A corresponds to FIG. 2A of the first embodiment, FIG. 6B corresponds to FIG. 2B, and FIG. 7 corresponds to FIG. Here, FIG. 6 is a diagram showing a state in which the three flow paths 23A, 23B, and 23C are arranged at equiangular intervals with the suction port 25 as the center.

As in the first embodiment, each of the flow paths 23A, 23B, and 23C has completely the same size and shape, and the rotational path C of FIG. They are arranged at angular intervals. Therefore, as shown in FIG. 6B, the regions where the flow paths 23A, 23B, and 23C are directed radially outward from the suction port 25 extend in directions that are 120 ° apart from each other.

  6B is a diagram showing the actual flow paths 23A, 23B, and 23C by the outer edges (indicated by dotted lines) of the pump blades 23, as in FIG. 2B. In the vicinity of the outer edge of the pump blade 23, discharge ports 27A, 27B, and 27C are formed over a wide angle range (about 120 °) as in the example of FIG. FIG. 7 is a cross-sectional view showing a state where pump blades are housed in the actual pump casing 26.

  In the pump blade 21 according to the present embodiment, sewage filth is discharged from the three flow paths 23A, 23B, and 23C three times for each rotation. For this reason, when it is assumed that the discharge flow rate is the same, the pressure fluctuation at the time of discharge is suppressed to be lower than that of the pump blade 11 of the first embodiment having two flow paths.

  In the above description, all the flow paths are the same size and shape, and the pump blades are arranged at equiangular intervals around each rotation axis. However, the fluid balance can be reduced by the pump blade having the above-described configuration. That is, as shown in FIG. 8A, even when one channel is thin and the remaining two channels are thick, the fluid balance can be reduced. On the contrary, a combination of two thin channels and one thick channel is possible.

  Further, as shown in FIG. 8B, the fluid balance can be reduced even when the angular intervals between the flow paths are not equal. In this way, by changing the angular interval, the intermittent flow (pulsation) in the volute can be increased, and the foreign matter dischargeability can be improved.

  FIG. 9 is a cross-sectional view of the submersible pump 60 including the above-described pump blade 11 according to the present embodiment. The pump blade 11 is accommodated in a pump casing 62 and is connected to a sealed submersible motor 63 for rotationally driving the pump blade 11. The submersible motor 63 includes a motor 66 including a stator 64 and a rotor 65, and a motor casing 67 that covers the motor 66. A drive shaft 68 extending in the vertical direction is provided at the center of the rotor 65. The upper end portion of the drive shaft 68 and the middle portion on the slightly lower side are rotatably supported by bearings 69 and 70, respectively. The pump blade 11 is connected to the lower end portion of the drive shaft 68.

  Inside the pump casing 62 is formed a pump chamber 76 defined by an inner wall 75 whose section is recessed in a semicircular shape. The discharge part 88 of the pump blade 11 is accommodated in the pump chamber 76. A suction portion 71 protruding downward is formed at the lower portion of the pump casing 62. The suction portion 71 is formed with a suction port 72 that opens downward. A discharge portion 73 projecting sideways is formed on the side of the pump casing 62. The discharge portion 73 is formed with a discharge port 74 that opens to the side.

  The pump blade according to the present invention can be used particularly for a submersible pump for sewage waste.

1, 11, 21 Pump blade 3 Channel 5 Suction port 7 Discharge port 13A, 13B Channel 15 Suction port 17A, 17B Discharge port 23A, 23B, 23C Channel 25 Suction port 26 Pump casing 27A, 27B, 27C Discharge port C Axis of rotation

Claims (9)

A substantially cylindrical body,
A suction port provided in the center of the lower end surface of the main body,
A discharge port opening in the side surface of the main body,
A non-clog type pump blade for a submersible pump comprising a flow path communicating from the suction port to the discharge port inside the main body,
There are a plurality of the flow paths, and the dimensions, shape, and positions of the flow paths are set so that these flow paths reduce the fluid imbalance with respect to the rotation axis.   The pump blade according to claim 1, wherein the number of the flow paths is two or more.   The pump blade according to claim 1, wherein the flow path has a cross-sectional area that varies between the suction port and the discharge port.   The pump blade according to any one of claims 1 to 3, wherein a cross-sectional shape of the flow path is changed between the suction port and the discharge port.   The pump blade according to claim 4, wherein a cross-sectional shape of the flow path changes from a circular shape to a substantially rectangular shape or an elliptical shape from the suction port toward the discharge port.   The pump blade according to any one of claims 1 to 5, wherein the flow path has an inner wall surface formed of a continuous curved surface.   The pump blade according to any one of claims 1 to 6, wherein inner walls of the at least two flow paths in the vicinity of branch portions have different surface roughnesses.   The pump blade according to any one of claims 1 to 7, wherein all the flow paths have the same size and shape and are arranged at equiangular intervals with respect to the rotation axis.   A submersible pump comprising the pump blade according to any one of claims 1 to 8, a pump casing that accommodates the pump blade, and a motor that drives the pump blade.