Impellers and pumps

Abstract

To provide an impeller capable of preventing blockage of a pump due to foreign matter.SOLUTION: An impeller 4 comprises a rotary projection 55 connected to a liquid inlet of a blade 52, and a groove 56.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an impeller and a pump.

Background Art

[0002] A pump is used to transfer a liquid such as sewage flowing through a sewer pipe.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Such sewage may contain foreign matters such as fibrous substances and solid substances. If such foreign matters adhere to and accumulate on the blades of the impeller, the pump may be blocked by the foreign matters.

[0005] Therefore, an object of the present invention is to provide an impeller and a pump that can prevent the pump from being blocked by foreign matters.

Means for Solving the Problems

[0006] In one aspect, a closed-type impeller is provided. The impeller includes a main plate and a side plate, blades disposed between the main plate and the side plate, a rotating protrusion connected to a liquid inlet of the blades, and a groove formed on an outer peripheral surface of the side plate and extending radially outward from the rotating protrusion toward the side plate.

[0007] In one aspect, the groove has a blade shape extending spirally from a base end portion of the rotating protrusion to an outermost peripheral surface of the side plate. In one embodiment, the angle between a first reference line perpendicular to the line segment connecting the axis of the impeller and the starting end of the groove, and the tangent to the starting end, is a first angle; the angle between a second reference line perpendicular to the line segment connecting the axis of the impeller and the ending end of the groove, and the tangent to the ending end, is a second angle; and the wing shape is determined based on the first angle and the second angle. In one embodiment, the impeller is equipped with a balance weight, and the groove and the balance weight eliminate dynamic imbalances that occur in the impeller. In one embodiment, the blade is a single blade extending in a spiral shape, with the liquid inlet positioned in the axial direction of the impeller and the liquid outlet of the blade positioned in the radial direction of the impeller.

[0008] In one embodiment, a pump is provided that comprises the impeller and a pump casing housing the impeller.

[0009] In one embodiment, the pump casing is provided with a stationary projection having an upper surface facing the rotating projection, the upper surface having regions having at least two angles. In one embodiment, the region is divided into a tip-side region located on the tip side of the rotating projection and a base-side region located on the base side of the rotating projection, and the angle between the tip-side region and the rotating projection is greater than the angle between the base-side region and the rotating projection. In one embodiment, the region is divided into a tip-side region located on the tip side of the rotating projection and a base-side region located on the base side of the rotating projection, and the angle between the base-side region and the rotating projection is greater than the angle between the tip-side region and the rotating projection.

[0010] In one embodiment, the upper surface has a boundary portion that divides the region into a tip-side region located on the tip side of the rotating projection and a base-side region located on the base-side of the rotating projection, and the gap between the boundary portion and the rotating projection is smaller than the gap between the tip-side region and the rotating projection and the gap between the base-side region and the rotating projection. In one embodiment, the stationary projection has a front side surface located forward in the direction of rotation of the impeller, and a rear side surface located backward in the direction of rotation of the impeller, and the front side surface and the rear side surface are connected to the upper surface. In one embodiment, the front side surface has a planar shape. In one embodiment, the front side surface has a shape that is bent at a predetermined angle. In one embodiment, the front side surface has a curved shape. [Effects of the Invention]

[0011] An impeller equipped with rotating protrusions and grooves can push out captured foreign objects. As a result, the impeller can reliably prevent blockage of the pump by foreign objects. [Brief explanation of the drawing]

[0012] [Figure 1] This figure shows one embodiment of a pump device. [Figure 2] This is a perspective view of the impeller. [Figure 3] This is a view from the direction of line A in Figure 2. [Figure 4] This is a perspective view of the rotating protrusion and groove. [Figure 5] This diagram shows the positional relationship between the rotating protrusions and grooves. [Figure 6] This figure shows the angle between the first reference line and the tangent line at the beginning of the groove. [Figure 7] This figure shows the angle between the second reference line and the tangent to the end of the groove. [Figure 8] This diagram shows the upper surface of the stationary projection opposite the rotating projection. [Figure 9] Figures 9(a) to 9(c) illustrate the angle between the upper surface of the rotating projection and the stationary projection. [Figure 10] This figure shows the front side view of a stationary projection having a planar shape. [Figure 11] This figure shows the front side view of a stationary projection bent at a predetermined angle. [Figure 12] It is a figure showing the front side surface of a stationary protrusion having a curved surface shape. [Figure 13] Figures 13(a) to 13(c) are figures showing the angle between the upper surface of the stationary protrusion and the front side surface of the stationary protrusion.

Embodiment for Carrying out the Invention

[0013] Hereinafter, embodiments will be described with reference to the drawings. FIG. 1 is a diagram showing an embodiment of a pump device. As shown in FIG. 1, a pump device PA includes a pump 1 for transferring a liquid and a motor 2 for driving the pump 1. In the embodiment shown in FIG. 1, the pump 1 is a pump for transferring a liquid such as sewage flowing through a sewer pipe.

[0014] The pump 1 includes a rotating shaft 3 connected to the motor 2, an impeller 4 fixed to an end of the rotating shaft 3, and a pump casing 5 for housing the impeller 4. The rotating shaft 3 is rotated by the motor 2, and the impeller 4 rotates together with the rotating shaft 3 inside the pump casing 5. A mechanical seal 6 attached to the rotating shaft 3 is disposed between the motor 2 and the impeller 4. The mechanical seal 6 prevents the liquid sucked into the pump 1 from entering the motor 2.

[0015] The pump casing 5 includes a casing body 10 disposed around the impeller 4 and a casing liner 11 connected to the casing body 10. The casing liner 11 has a suction port 12 formed in the central portion thereof. The casing body 10 has a volute chamber (scroll chamber) 13 formed inside thereof and a discharge port 14 connected to the volute chamber 13. The volute chamber 13 has a shape surrounding the impeller 4.

[0016] The impeller 4 is fixed to the end of the rotating shaft 3 by fasteners 7. When the impeller 4 rotates due to the drive of the motor 2, the liquid is drawn in through the suction port 12. The liquid is given kinetic energy by the rotation of the impeller 4, and as the liquid passes through the volute chamber 13, the kinetic energy is converted into pressure energy, and the liquid is pressurized. The pressurized liquid is discharged from the discharge port 14.

[0017] Figure 2 is a perspective view of the impeller. Figure 3 is a view from the direction of line A in Figure 2. As shown in Figures 1 to 3, the impeller 4 is a closed-type impeller. More specifically, the impeller 4 comprises a main plate 50 and side plates 51, and blades 52 positioned between the main plate 50 and the side plates 51.

[0018] The liquid inlet 53 of the blade 52 is in communication with the suction port 12 of the pump casing 5, and the liquid outlet 60 of the blade 52 is in communication with the discharge port 14 of the pump casing 5. In this embodiment, the blade 52 is a single blade that extends in a spiral shape, with the liquid inlet 53 positioned in the axial direction of the impeller 4 (i.e., in the CL direction of the axis of rotation 3), and the liquid outlet 60 of the blade 52 (see Figure 1) positioned in the radial direction of the impeller 4.

[0019] The impeller 4 has an internal flow path 61 formed inside it, and an external flow path 62 connected to the internal flow path 61 and extending to surround the blades 52. The liquid inlet 53 communicates with the internal flow path 61, and the external flow path 62 connected to the internal flow path 61 communicates with the liquid outlet 60.

[0020] The internal flow path 61 extends spirally along the axial direction of the impeller 4, while the external flow path 62 extends perpendicular to the axial direction of the impeller 4 (i.e., perpendicular to the axis CL of the rotation shaft 3). The external flow path 62 of the impeller 4 corresponds to the volute chamber 13 of the pump casing 5.

[0021] The white arrows in Figure 1 and Figure 2 indicate the flow direction of the liquid drawn into the pump casing 5. The liquid drawn in from the suction port 12 and the liquid inlet 53 passes through the internal flow path 61 along the axis of the impeller 4, and then passes through the external flow path 62 (i.e., the volute chamber 13) in a direction perpendicular to the axis of the impeller 4. The liquid that has passed through the external flow path 62 is discharged to the outside from the liquid outlet 60 and the discharge port 14.

[0022] As mentioned above, wastewater may contain foreign matter. Semi-open pumps have higher clogging properties compared to closed pumps, and are therefore sometimes used as drainage pumps for wastewater. However, semi-open pumps are less efficient than closed pumps. In other words, there is a trade-off relationship between pump clogging properties and pump efficiency.

[0023] Therefore, in this embodiment, the pump 1 is equipped with an impeller 4 that has high blockage resistance and high pumping efficiency, and reliably prevents blockage of the pump by foreign matter. The structure of the impeller 4 will be described below.

[0024] Figure 4 is a perspective view of the rotating projection and groove. As shown in Figures 1 to 4, the impeller 4 includes a rotating projection 55 connected to the liquid inlet 53 of the blade 52, and a groove (impeller side groove) 56 formed on the outer peripheral surface 51a of the side plate 51 and extending radially outward from the base end 55a of the rotating projection 55 to the side plate 51.

[0025] The rotating projection 55 is connected to the lowest end of the side plate 51 and protrudes radially inward from the side plate 51. In other words, the rotating projection 55 protrudes from the liquid inlet 53 in such a way that it obstructs the flow path of the liquid passing through the liquid inlet 53.

[0026] The rotating projection 55 may be integrally molded with the side plate 51, or it may be made of a different material from the side plate 51. By making the rotating projection 55 from a different material from the side plate 51, even if the rotating projection 55 wears out, the worker can easily replace it.

[0027] Figure 5 shows the positional relationship between the rotating projection and the groove. As shown in Figure 5, the groove 56 is connected to the rotating projection 55. The groove 56 has a spirally extending wing shape to move foreign matter that enters the groove 56 to the liquid outlet 60 of the wing 52. More specifically, the groove 56 forms a flow that moves the liquid containing foreign matter from the liquid inlet 53 to the liquid outlet 60 as the impeller 4 rotates.

[0028] Figure 6 shows the angle between the first reference line and the tangent to the starting end of the groove. Figure 7 shows the angle between the second reference line and the tangent to the ending end of the groove. As shown in Figures 6 and 7, the groove 56 has a starting end 56a adjacent to the rotating projection 55 and an ending end 56b adjacent to the outermost circumferential surface 51b of the side plate 51.

[0029] The outer peripheral surface 51a of the side plate 51 faces the casing liner 11, and the outermost peripheral surface 51b of the side plate 51 is located on the outermost side of the outer peripheral surface 51a. In this embodiment, the groove 56 extends from the liquid inlet 53 to the outermost peripheral surface 51b, and when the impeller 4 is viewed from its axial direction (i.e., the axial direction CL), the groove 56 has a boomerang shape that extends in an arc. More specifically, the area of ​​the groove 56 gradually increases from the starting end 56a and gradually decreases towards the ending end 56b.

[0030] As shown in Figure 6, the angle θa between the first reference line RL1, which is perpendicular to the line segment connecting the axis of the impeller 4 and the starting end 56a of the groove 56, and the tangent line TL1 to the starting end 56a, is the first angle. In this embodiment, the first angle θa is acute.

[0031] As shown in Figure 7, the angle θb between the second reference line RL2, which is perpendicular to the line segment connecting the axis of the impeller 4 and the end portion 56b of the groove 56, and the tangent line TL2 of the end portion 56b, is the second angle. In this embodiment, the second angle θb is acute.

[0032] As described above, the groove 56 has an airfoil shape that moves the liquid from the liquid inlet 53 to the liquid outlet 60. Such an airfoil shape is determined based on a first angle θa and a second angle θb. The first angle θa and the second angle θb are determined based on various conditions such as the size of the impeller 4 and the properties of the liquid being handled.

[0033] In conventional pumps, a liner ring (not shown) is attached to the suction port 12 side to prevent backflow of liquid. In this embodiment, since the groove 56 has a structure (i.e., a vane shape) that prevents backflow of liquid, there is no need to attach a liner ring to the pump casing 5. As a result, the number of parts can be reduced, and the overall cost of the pump device PA can be reduced.

[0034] Returning to Figure 1, the pump casing 5 is equipped with a stationary projection (i.e., a cutter) 30 for cutting (and / or grinding) foreign matter. The stationary projection 30 is fixed to the casing liner 11 and protrudes from the suction port 12 so as to obstruct the flow path of liquid passing through the suction port 12.

[0035] In this embodiment, the stationary projection 30 is made of a different material from the casing liner 11 and is fixed to the casing liner 11 by fasteners 32. With this configuration, even if the stationary projection 30 wears out, the worker can easily replace it. In one embodiment, the stationary projection 30 may be an integrally molded member with the casing liner 11.

[0036] As shown in Figure 3, the stationary projection 30 has an upper surface 35 facing the rotating projection 55, a front side surface 36 located forward in the direction of rotation of the impeller 4 (see arrow in Figure 3), a rear side surface 37 located backward in the direction of rotation of the impeller 4, and a lower surface 38 located opposite the upper surface 35. The front side surface 36 and the rear side surface 37 are connected to the upper surface 35 and the lower surface 38.

[0037] In this embodiment, when transferring a liquid that does not contain foreign matter, the pump device PA can drain the liquid through the internal passage 61 and the external passage 62 by rotating the impeller 4, which has high pumping efficiency. When transferring a liquid that contains foreign matter, when the impeller 4 rotates due to the drive of the motor 2, the foreign matter contained in the liquid is captured by the rotating projection 55. Meanwhile, the liquid is discharged from the discharge port 14 through the internal passage 61 and the external passage 62.

[0038] Foreign matter captured by the rotating projection 55 enters the gap between the rotating projection 55 and the stationary projection 30 due to the rotation of the impeller 4, and is cut (crushed) by the stationary projection 30. More specifically, the foreign matter is pressed into the groove 56 while being crushed by the rotating projection 55, while being sandwiched between the upper surface 35 of the stationary projection 30 and the rotating projection 55. The foreign matter pressed into the groove 56 moves along the groove 56 due to the rotation of the impeller 4, and is discharged into the volute chamber 13 (i.e., the external flow path 62) at the end portion 56b of the groove 56. The wing-shaped groove 56 can prevent not only the backflow of liquid but also the backflow of foreign matter.

[0039] According to this embodiment, the impeller 4 is equipped with a rotating projection 55 and a groove 56 formed on the outer peripheral surface 51a of the side plate 51. Therefore, the pump 1 can move foreign matter through a passage located outside the internal passage 61 of the blade 52 (i.e., the gap between the casing liner 11 and the outer peripheral surface 51a of the side plate 51). As a result, the impeller 4 can prevent foreign matter from passing through the internal passage 61. With this configuration, the impeller 4 can reliably prevent blockage of the pump by foreign matter.

[0040] In one embodiment, the pump casing 5 may have a groove (pump casing side groove) 40 formed on its inner surface (see Figures 2 and 3). The groove 40 is located upstream of the stationary projection 30 in the rotational direction of the impeller 4 and is adjacent to the stationary projection 30.

[0041] More specifically, the groove 40 is formed on the inner surface 11a of the casing liner 11 (see Figures 1 and 2) and extends from the suction port 12 toward the volute chamber 13. The groove 40 can more actively move foreign matter that has entered between the impeller 4 and the pump casing 5 toward the volute chamber 13.

[0042] As shown in Figure 1, the impeller 4 is equipped with a balance weight 80. The groove 56 and the balance weight 80 eliminate the dynamic unbalance that occurs in the impeller 4. Dynamic unbalance is a combination of static unbalance that occurs when the impeller 4 is stationary and even unbalance that occurs when the impeller 4 is rotating.

[0043] In this embodiment, the groove 56 is a recess formed in the outer circumferential surface 51a of the side plate 51. Therefore, the impeller 4 with the groove 56 can eliminate its static imbalance. More specifically, the operator can eliminate the static imbalance by determining the position where the groove 56 is formed based on the static imbalance occurring in the impeller 4.

[0044] The impeller 4 experiences not only static unbalance but also even unbalance. Therefore, in this embodiment, the impeller 4 is equipped with a balance weight 80 embedded in the main plate 50. The position in which the balance weight 80 is embedded is determined based on the position of the even unbalance, which is measured by rotating the impeller 4.

[0045] According to this embodiment, by forming the groove 56 in the impeller 4, static unbalance can be eliminated without embedding a new balance weight (not shown). By embedding the balance weight 80, even unbalance can be eliminated. In this way, the groove 56 and the balance weight 80 can eliminate dynamic unbalance that occurs in the impeller 4. As a result, the impeller 4 does not need to have more balance weights than necessary, and therefore the cost of the impeller 4 can be reduced.

[0046] Figure 8 shows the upper surface of a stationary projection facing a rotating projection. As shown in Figure 8, the upper surface 35 of the stationary projection 30 has regions with at least two angles (inclination angles). In this embodiment, the upper surface 35 of the stationary projection 30 has a tip-side region 35A located on the tip side of the rotating projection 55, a base-side region 35B located on the base-side of the rotating projection 55, and a boundary portion 35C located between the tip-side region 35A and the base-side region 35B. The black dot indicating the boundary portion 35C is a hypothetical point to clearly show the position of the boundary portion 35C.

[0047] The region formed on the upper surface 35 of the stationary projection 30 is divided by a boundary portion 35C into a tip-side region 35A and a base-side region 35B. The base-side region 35B slopes downward from the base end to the tip end of the stationary projection 30, and the tip-side region 35A slopes downward from the base-side region 35B towards the tip end of the stationary projection 30.

[0048] Figures 9(a) to 9(c) illustrate the angle between the upper surface of the rotating projection and the stationary projection. Note that in Figures 9(a) to 9(c), the angles are exaggerated for clarity. As shown in Figure 9(a), the rotating projection 55 extends inclined upward with respect to the horizontal line HL. As shown in Figure 9(b), the angle θ1 between the tip-side region 35A and the rotating projection 55 is greater than the angle θ2 between the base-side region 35B and the rotating projection 55 (θ1 > θ2). Because angle θ1 is greater than angle θ2, foreign matter actively enters the gap between the tip-side region 35A of the upper surface 35 and the rotating projection 55.

[0049] As shown in Figure 9(b), the gap between the boundary portion 35C and the rotating projection 55 is smaller than the gap between the tip-side region 35A and the rotating projection 55 and the gap between the base-side region 35B and the rotating projection 55. In other words, the boundary portion 35C is closest to the rotating projection 55 on the upper surface 35 of the stationary projection 30. Therefore, foreign matter moving from the tip-side region 35A to the base-side region 35B is crushed and cut into smaller pieces by the rotating projection 55 and the boundary portion 35C.

[0050] As shown in Figure 9(c), angle θ1 may be smaller than angle θ2 (θ1 < θ2). In other words, the angle θ2 between the base region 35B and the rotating projection 55 is larger than the angle θ1 between the tip region 35A and the rotating projection 55. With this structure, foreign matter that enters the gap between the tip region 35A and the rotating projection 55 is actively ground up by the tip region 35A and the rotating projection 55. In the embodiment shown in Figure 9(c), the boundary portion 35C is closest to the rotating projection 55 on the upper surface 35 of the stationary projection 30. Therefore, foreign matter is more finely cut by the rotating projection 55 and the boundary portion 35C.

[0051] Figure 10 shows the front side view of a stationary projection having a planar shape. Figure 11 shows the front side view of a stationary projection bent at a predetermined angle. Figure 12 shows the front side view of a stationary projection having a curved shape.

[0052] In the embodiment shown in Figure 10, the front side surface 36 of the stationary projection 30 has a planar shape parallel to the vertical line VL that extends perpendicular to the axial line CL. In the embodiment shown in Figure 11, the front side surface 36 that extends parallel to the vertical line VL has a shape that bends in the direction of rotation of the impeller 4 (see arrow in Figure 11). In the embodiment shown in Figure 12, the front side surface 36 has a curved shape that extends in an arc in the direction of rotation of the impeller 4 (see arrow in Figure 12).

[0053] Figures 13(a) to 13(c) show the angle between the upper surface of the stationary projection and the front side surface of the stationary projection. As shown in Figures 13(a) and 13(c), the angle θΔ between the upper surface 35 and the front side surface 36 may be acute, or as shown in Figure 13(b), the angle θΔ may be a right angle (90 degrees). If the angle θΔ is acute, it may be between 45 and 58 degrees. Although not shown, the angle θΔ may be obtuse if the above-mentioned effects can be achieved.

[0054] In the embodiment shown in Figure 13(c), the stationary projection 30 does not have a lower surface 38, and the vertical cross-sectional shape of the stationary projection 30 is triangular. As shown in Figures 13(a) to 13(c), the vertical cross-sectional shape of the stationary projection 30 may be square or triangular.

[0055] In the embodiment described above, a closed-type impeller 4 having one blade 52 was described, but the number of blades 52 is not limited to this embodiment. In one embodiment, the impeller 4 may be a closed-type impeller having multiple blades. Even in this case, the impeller 4 having the rotating projection 55 and groove 56 can achieve the same effects as the impeller 4 according to the embodiment described above.

[0056] In the embodiments described above, the upper surface 35 of the stationary projection 30 having two regions (i.e., the tip-side region 35A and the base-side region 35B) was described, but the regions of the upper surface 35 of the stationary projection 30 are not limited to two. In one embodiment, the upper surface 35 of the stationary projection 30 may have regions having three or more angles (inclination angles).

[0057] The embodiments described above are intended to enable persons with ordinary skill in the art to implement the present invention. Various modifications of the above embodiments can be made naturally by those skilled in the art, and the technical idea of ​​the present invention can be applied to other embodiments as well. Therefore, the present invention is not limited to the embodiments described, but should be in the broadest scope according to the technical idea defined by the claims. [Explanation of symbols]

[0058] 1 pump 2 motors 3 rotation axes 4-blade wheel 5 Pump casing 6 Mechanical seals 7 Fasteners 10 Casing body 11 Casing Liner 11a Inner Self 12 Inlet 13 Volute Room 14 Outlet 30 Stationary projection 35 Top 35A Tip side area 35B Proximal area 35C Boundary 36 Front side 37 Rear side 38 Bottom side 40 grooves (pump casing side grooves) 50 Main plate 51 Side panel 51a Outer surface 51b Outermost surface 52 Wings 53 Liquid inlet 55 Rotating protrusions 55a Proximal end 56. Groove (Impeller side groove) 56a Starting point 56b Termination 60 liquid outlet 61 Internal flow path 62 External channel 80 Balance Weights

Claims

1. A closed-type impeller, The impeller is a main plate and a side plate; a wing disposed between the main plate and the side plate; a rotating projection connected to the liquid inlet of the vane; a groove formed on the outer peripheral surface of the side plate and extending from the rotation protrusion toward the radially outer side of the side plate.

2. The impeller according to claim 1 , wherein the groove has a blade shape that extends spirally from a base end of the rotation projection to the outermost peripheral surface of the side plate.

3. an angle between a first reference line perpendicular to a line segment connecting an axis of the impeller and a start end of the groove and a line tangent to the start end is a first angle; an angle between a second reference line perpendicular to a line segment connecting the axis of the impeller and the terminal end of the groove and a tangent to the terminal end is a second angle; The impeller of claim 2 , wherein the blade shape is determined based on the first angle and the second angle.

4. The impeller is provided with a balance weight, The impeller according to any one of claims 1 to 3, wherein the groove and the balance weight eliminate dynamic imbalance occurring in the impeller.

5. The impeller according to any one of claims 1 to 4, wherein the blade is a single blade extending in a spiral shape, with the liquid inlet being arranged in an axial direction of the impeller and the liquid outlet of the blade being arranged in a radial direction of the impeller.

6. An impeller according to any one of claims 1 to 5; a pump casing that houses the impeller.

7. the pump casing includes a stationary protrusion having an upper surface facing the rotating protrusion; The pump of claim 6 , wherein the upper surface has at least two angled regions.

8. The region is a tip side region disposed on the tip side of the rotation protrusion; a base end region disposed on the base end side of the rotation projection, 8. The pump of claim 7, wherein an angle between the distal region and the rotation projection is greater than an angle between the proximal region and the rotation projection.

9. The region is a tip side region disposed on the tip side of the rotation protrusion; a base end region disposed on the base end side of the rotation projection, 8. The pump of claim 7, wherein an angle between the proximal region and the rotation projection is greater than an angle between the distal region and the rotation projection.

10. the upper surface has a boundary portion that divides the region into a distal region disposed on the distal end side of the rotary protrusion and a proximal region disposed on the proximal end side of the rotary protrusion, A pump according to any one of claims 7 to 9, wherein the gap between the boundary portion and the rotary protrusion is smaller than the gap between the tip side region and the rotary protrusion and the gap between the base side region and the rotary protrusion.

11. The stationary protrusion is a front side surface located forward in the rotation direction of the impeller; a rear side surface located rearward in the rotation direction of the impeller, The pump according to any one of claims 6 to 10, wherein the front side surface and the rear side surface are connected to the top surface.

12. The pump of claim 11 , wherein the front side has a planar shape.

13. The pump according to claim 11, wherein the front side surface has a shape that is bent at a predetermined angle.

14. The pump of claim 11 , wherein the front side has a curved shape.

Images