Pump casing and pump

Abstract

To provide a pump casing that can prevent a pump from being clogged with foreign substances.SOLUTION: A pump casing 5 comprises a cutter 30 comprising an upper surface 35 opposed to a front edge part 20 of an impeller 4 when the impeller 4 is housed in the pump casing 5. The upper surface 35 comprises a region having at least two angles.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a pump casing and a pump. [Background technology]

[0002] 2. Description of the Related Art Pumps (particularly centrifugal pumps) are used to transport liquids such as sewage flowing through sewer pipes. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-143630 Summary of the Invention [Problem to be solved by the invention]

[0004] Such wastewater may contain foreign matter such as fibrous or solid matter, which may adhere to and accumulate on the impeller blades, causing the pump to become clogged.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a pump casing and a pump that can prevent the pump from being clogged by foreign matter. [Means for solving the problem]

[0006] In one aspect, a pump casing capable of housing an impeller is provided, the pump casing including a cutter having an upper surface facing a leading edge of the impeller when the impeller is housed in the pump casing, the upper surface having at least two angled regions.

[0007] In one aspect, the region is divided into an inner end region located on the inner end side of the leading edge portion and an outer end region located on the outer end side of the leading edge portion, and the angle between the inner end region and the leading edge portion is greater than the angle between the outer end region and the leading edge portion. In one aspect, the region is divided into an inner end region located on the inner end side of the leading edge portion and an outer end region located on the outer end side of the leading edge portion, and the angle between the outer end region and the leading edge portion is greater than the angle between the inner end region and the leading edge portion. In one aspect, the upper surface has a boundary portion that divides the region into an inner end region located on the inner end side of the leading edge portion and an outer end region located on the outer end side of the leading edge portion, and the gap between the boundary portion and the leading edge portion is smaller than the gap between the inner end region and the leading edge portion and the gap between the outer end region and the leading edge portion.

[0008] In one embodiment, the boundary portion has a curved shape that smoothly connects the inner end region and the outer end region. In one embodiment, the boundary portion has a corner shape that connects the inner end region and the outer end region at a predetermined angle. In one aspect, the pump casing includes a casing body that can be disposed around the impeller, and a casing liner that is connected to the casing body and has the cutter fixed thereto.

[0009] In one embodiment, the cutter is constructed from a member different from the casing liner. In one aspect, the cutter is an integral part of the casing liner. In one aspect, the cutter has a front side surface that is located forward in the direction of rotation of the impeller when the impeller is housed in the pump casing, and a rear side surface that is located rearward in the direction of rotation of the impeller when the impeller is housed in the pump casing, and the front side surface and the rear side surface are connected to the upper surface.

[0010] In one aspect, the front side has a planar shape. In one embodiment, the front side surface has a shape that is bent at a predetermined angle. In one aspect, the front side has a curved shape.

[0011] In one aspect, the pump casing has an inlet and an outlet, and the cutter is disposed on the opposite side of the outlet with respect to the center of the inlet. In one aspect, the pump casing has a groove formed in an inner surface thereof, the groove being located adjacent to the cutter.

[0012] In one aspect, a pump is provided comprising an impeller and the above-described pump casing housing the impeller. [Effects of the Invention]

[0013] The pump casing is provided with a cutter that faces the leading edge of the impeller. Therefore, even if foreign matter contained in the liquid is sucked into the pump casing, the cutter cuts (and / or grinds) the foreign matter. As a result, the pump casing can prevent the pump from being clogged by foreign matter. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 illustrates an embodiment of a pump device. [Figure 2] FIG. 2 is a cross-sectional view taken along line AA in FIG. [Figure 3] FIG. 10 is a view of the cutter as seen from diagonally above. [Figure 4] FIG. 10 is a view of the cutter as seen from diagonally below. [Figure 5] 10A and 10B show another embodiment of a cutter. [Figure 6] FIG. 4 is a diagram showing the positional relationship between a discharge port and a cutter. [Figure 7] FIG. 10 shows the top surface of the cutter opposite the leading edge. [Figure 8]8(a) to 8(c) are diagrams illustrating the angle between the leading edge of the blade and the upper surface of the cutter. [Figure 9] FIG. 10 is a view showing a plurality of grooves formed on the inner surface of the pump casing. [Figure 10] FIG. 10 is a view showing the front side of a cutter having a planar shape. [Figure 11] FIG. 10 is a view showing the front side of the cutter bent at a predetermined angle. [Figure 12] FIG. 10 is a view showing the front side of a cutter having a curved surface. [Figure 13] 13(a) to 13(c) are diagrams showing the angle between the top surface of the cutter and the front side surface of the cutter. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, embodiments will be described with reference to the drawings. Fig. 1 is a diagram showing one embodiment of a pump device. As shown in Fig. 1, the pump device PA includes a pump 1 that transfers a liquid and a motor 2 that drives the pump 1. In the embodiment shown in Fig. 1, the pump 1 is a centrifugal pump for transferring a liquid such as sewage flowing through a sewer pipe.

[0016] Pump 1 includes a rotating shaft 3 connected to motor 2, an impeller 4 fixed to the end of the rotating shaft 3, and a pump casing 5 that houses the impeller 4. The rotating shaft 3 is rotated by 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 liquid sucked into the pump 1 from entering the motor 2.

[0017] The pump casing 5 includes a casing body 10 arranged 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 its central portion. The casing body 10 has a volute chamber 13 formed therein, and a discharge port 14 connected to the volute chamber 13. The volute chamber 13 has a shape that surrounds the impeller 4.

[0018] 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, liquid is sucked in through the suction port 12. The rotation of the impeller 4 imparts velocity energy to the liquid, and as the liquid passes through the volute chamber 13, the velocity energy is converted into pressure energy, and the liquid is pressurized. The pressurized liquid is discharged from the discharge port 14. The blades 15 of the impeller 4 face the inner surface 11a of the casing liner 11, and a gap of a predetermined size is formed between the blades 15 and the inner surface 11a.

[0019] Fig. 2 is a cross-sectional view taken along line AA in Fig. 1. As shown in Fig. 2, the impeller 4 includes a plurality of blades 15 (two in this embodiment) and a boss portion 16 to which the blades 15 are fixed. The blades 15 rotate together with the rotary shaft 3 around the boss portion 16 (see the solid arrow in Fig. 2).

[0020] As shown in Figure 2, the pump casing 5 has a tongue portion 25 that forms the beginning of the spiral of the volute chamber 13. The volute chamber 13 extends circumferentially around the impeller 4, and the liquid flowing through the volute chamber 13 is divided by the tongue portion 25. Therefore, most of the liquid flows to the discharge port 14, while a portion of the liquid circulates through the volute chamber 13 (see the dotted arrows in Figure 2).

[0021] 2, the wing 15 is a swept-back wing. More specifically, the wing 15 has a leading edge 20 that extends spirally from the boss 16 and a trailing edge 21 that extends spirally from the leading edge 20. The leading edge 20 and the trailing edge 21 are connected to each other and are integrally formed.

[0022] The leading edge portion 20 is disposed radially inward of the suction port 12. The trailing edge portion 21 faces the inner surface 11a of the casing liner 11 (see FIG. 1). Therefore, when the casing liner 11 is viewed from the direction of the axis CL of the rotating shaft 3, the leading edge portion 20 is disposed so as to be exposed from the casing liner 11, and the trailing edge portion 21 is disposed on the back side of the casing liner 11.

[0023] As described above, the pumped liquid of the pump device PA may contain foreign matter such as fibrous matter and solid matter. The leading edge portion 20 of the blade 15 is located radially inward of the suction port 12. Therefore, when the pumped liquid is sucked into the suction port 12 by the rotation of the impeller 4, the foreign matter may adhere to and accumulate on the leading edge portion 20. When the impeller 4 rotates in this state, the foreign matter may become trapped in the gap between the trailing edge portion 21 and the inner surface 11a of the casing liner 11, which may result in the pump 1 being clogged.

[0024] Therefore, in order to prevent the pump from being clogged by foreign matter, the pump 1 (more specifically, the pump casing 5) is provided with a cutter 30 that cuts (and / or grinds) the foreign matter. The configuration of the cutter 30 will be described below with reference to the drawings.

[0025] Fig. 3 is a view of the cutter as viewed obliquely from above. Fig. 4 is a view of the cutter as viewed obliquely from below. The shape of the cutter 30 is not particularly limited, but in the embodiment shown in Figs. 3 and 4, the cutter 30 has a tapered shape when viewed from the direction of the axis CL. The cutter 30 is fixed to the casing liner 11 of the pump casing 5 and protrudes from the suction port 12 so as to obstruct the flow path of liquid passing through the suction port 12. The cutter 30 has a length that covers the leading edge portion 20.

[0026] In the embodiment shown in Fig. 4, the casing liner 11 has a cutter mounting portion 31 connected to the suction port 12. The cutter mounting portion 31 is a recess extending radially outward from the suction port 12, and the cutter 30 is fixed to the cutter mounting portion 31 by two fasteners 32. The number of fasteners 32 is not limited to this embodiment. When the impeller 4 is housed in the pump casing 5, a gap of a predetermined size is formed between the cutter 30 and the leading edge portion 20.

[0027] In this embodiment, the cutter 30 is made of a member different from the casing liner 11. With this configuration, even if the cutter 30 wears out, an operator can easily replace the cutter 30. Furthermore, by placing a spacer (not shown) between the cutter 30 and the casing liner 11, an operator can adjust the size of the gap between the cutter 30 and the leading edge 20. In one embodiment, the cutter 30 may be a member integrally molded with the casing liner 11.

[0028] The cutter 30 has an upper surface 35 that faces the leading edge portion 20 of the blade 15 when the impeller 4 is housed in the pump casing 5, a front side surface 36 that is located forward in the rotation direction of the impeller 4 (see the arrow in FIG. 4), a rear side surface 37 that is located rearward in the rotation direction of the impeller 4, and a lower surface 38 that is located opposite the upper surface 35. In this embodiment, the front side surface 36 and the rear side surface 37 are connected to the upper surface 35 and the lower surface 38, and the vertical cross-sectional shape of the cutter 30 is rectangular.

[0029] Figure 5 shows another embodiment of the cutter. In the embodiment shown in Figure 5, the cutter 30 does not have a lower surface 38, and the vertical cross-sectional shape of the cutter 30 is triangular. In this way, the vertical cross-sectional shape of the cutter 30 may be rectangular or triangular.

[0030] When the impeller 4 is rotated by the drive of the motor 2, foreign matter contained in the liquid is captured by the cutter 30 arranged at the suction port 12. The captured foreign matter is cut by the cutter 30. A portion of the cut foreign matter is received by the front side surface 36 of the cutter 30 and moved to the volute chamber 13 by the rotating impeller 4. The foreign matter is then discharged to the outside through the discharge port 14.

[0031] The remaining part of the cut foreign matter enters the gap between the upper surface 35 and the leading edge portion 20 and is cut (crushed) by the cutter 30. More specifically, while sandwiched between the upper surface 35 and the leading edge portion 20, the foreign matter moves toward the trailing edge portion 21 while being crushed by the rotating leading edge portion 20. The foreign matter then moves into the volute chamber 13 and is discharged to the outside through the discharge port 14.

[0032] 4 and 5, the cutter 30 has a different structure. The liquid containing foreign matter is forcefully sucked into the pump casing 5. Therefore, the cutter 30 can cut the captured foreign matter regardless of its longitudinal cross-sectional shape (see FIGS. 4 and 5).

[0033] FIG. 6 is a diagram showing the positional relationship between the discharge port and the cutter. As shown in FIG. 6, the cutter 30 is disposed on the opposite side of the discharge port 14 with respect to the center CP of the suction port 12. The center CP of the suction port 12 coincides with the direction of the axial line CL. The tongue portion 25 is disposed adjacent to the discharge port 14. With this arrangement, foreign matter is released into the volute chamber 13 at a position opposite the tongue portion 25. The foreign matter is then subjected to centrifugal force and moves through the volute chamber 13 by the flowing liquid. Therefore, the foreign matter is discharged to the outside from the discharge port 14 without getting caught on the tongue portion 25. As a result, foreign matter is prevented from getting caught on the tongue portion 25.

[0034] FIG. 7 is a diagram showing the upper surface of the cutter facing the leading edge portion. As shown in FIG. 7, the upper surface 35 of the cutter 30 has regions having at least two angles (inclination angles). In this embodiment, the upper surface 35 of the cutter 30 has an inner end region 35A located on the inner end side of the leading edge portion 20, an outer end region 35B located on the outer end side of the leading edge portion 20, and a boundary region 35C located between the inner end region 35A and the outer end region 35B. The inner end region 35A is located on the distal end side of the cutter 30 and may therefore be referred to as the distal end region. Similarly, the outer end region 35B is located on the proximal end side of the cutter 30 and may therefore be referred to as the proximal end region. Note that the black dot indicating the boundary region 35C is a virtual point used to clearly indicate the position of the boundary region 35C.

[0035] The inner end of the leading edge 20 is defined as the portion of the leading edge 20 adjacent to the boss portion 16, and the outer end of the leading edge 20 is defined as the portion of the leading edge 20 adjacent to the trailing edge 21. In this embodiment, the area formed on the upper surface 35 of the cutter 30 is divided into an inner end region 35A and an outer end region 35B by a boundary portion 35C. The outer end region 35B slopes downward from the base end side toward the tip end side of the cutter 30, and the inner end region 35A slopes downward from the outer end region 35B toward the tip end side of the cutter 30.

[0036] Figures 8(a) to 8(c) are diagrams illustrating the angle between the leading edge of the blade and the upper surface of the cutter. Note that in Figures 8(a) to 8(c), the angle is exaggerated to make the drawings easier to see.

[0037] 8(a), when the impeller 4 is housed in the pump casing 5, the boss portion 16 extends parallel to the horizontal line HL, and the leading edge portion 20 extends at an upward incline relative to the horizontal line HL. In other words, the leading edge portion 20 has a tapered shape that extends obliquely upward with the boss portion 16 as the center.

[0038] 8(b), the angle θ1 between the inner end region 35A and the leading edge portion 20 is larger than the angle θ2 between the outer end region 35B and the leading edge portion 20 (θ1>θ2). Because the angle θ1 is larger than the angle θ2, foreign matter contained in the liquid actively enters the gap between the inner end region 35A of the upper surface 35 and the leading edge portion 20. The rotation of the leading edge portion 20 moves the foreign matter that has entered the gap from the inner end region 35A to the outer end region 35B.

[0039] 8(b), the gap between the boundary portion 35C and the leading edge portion 20 is smaller than the gap between the inner end region 35A and the leading edge portion 20 and the gap between the outer end region 35B and the leading edge portion 20. In other words, the boundary portion 35C is closest to the leading edge portion 20 on the upper surface 35 of the cutter 30. Therefore, foreign matter moving from the inner end region 35A to the outer end region 35B is crushed by the leading edge portion 20 and the boundary portion 35C and cut into smaller pieces.

[0040] The boundary portion 35C may have a curved shape that smoothly connects the inner end region 35A and the outer end region 35B, or may have an angular shape that connects the inner end region 35A and the outer end region 35B at a predetermined angle (more specifically, an obtuse angle). The shape of the boundary portion 35C may be determined based on factors such as the material, size, and length of the foreign matter contained in the liquid.

[0041] In this embodiment, the inner end region 35A and the outer end region 35B each have a planar shape. In one embodiment, at least one of the inner end region 35A and the outer end region 35B may have a curved surface shape that extends in an arc shape in a direction approaching the leading edge 20 (i.e., a convex shape). In another embodiment, at least one of the inner end region 35A and the outer end region 35B may have a curved surface shape that extends in an arc shape in a direction away from the leading edge 20 (i.e., a concave shape). The inner end region 35A and the outer end region 35B may have curved surface shapes with the same curvature or different curvatures.

[0042] In this embodiment, boundary 35C is located adjacent to the central portion of leading edge 20 (see FIG. 7). In one embodiment, boundary 35C may be located closer to the inner end than the central portion of leading edge 20, and in another embodiment, boundary 35C may be located closer to the outer end than the central portion of leading edge 20.

[0043] As described above, angle θ2 is smaller than angle θ1. Therefore, foreign matter passing through boundary portion 35C is actively crushed by outer end region 35B and leading edge portion 20. The crushed foreign matter is released into volute chamber 13 together with the liquid.

[0044] The pump casing 5 may have a groove 40 formed on its inner surface (see FIG. 3 ). The groove 40 is disposed upstream of the cutter 30 in the rotation direction of the impeller 4 and is adjacent to the cutter 30. More specifically, the groove 40 is formed on the inner surface 11 a of the casing liner 11 and extends from the suction port 12 toward the volute chamber 13. The front side surface 36 of the cutter 30 is connected to the starting end 40 a of the groove 40, and the ending end 40 b of the groove 40 is connected to the volute chamber 13.

[0045] Fig. 9 is a diagram showing a plurality of grooves formed on the inner surface of a pump casing. As shown in Fig. 9, the pump casing 5 may have a plurality of grooves 40 formed on its inner surface. In the embodiment shown in Fig. 9, the plurality of grooves 40 are arranged along the circumferential direction of the suction port 12, and the cutter 30 is arranged adjacent to one of the plurality of grooves 40. The cutter 30 shown in Fig. 9 has the same structure as the cutter 30 according to the embodiment shown in Fig. 5, but may also have the same structure as the cutter 30 according to the embodiment shown in Fig. 3.

[0046] In the embodiment shown in FIG. 8(b), the angle θ1 is greater than the angle θ2. However, as shown in FIG. 8(c), the angle θ1 may be smaller than the angle θ2 (θ1<θ2). In other words, the angle θ2 between the outer end region 35B and the leading edge 20 is greater than the angle θ1 between the inner end region 35A and the leading edge 20. With this structure, foreign matter that enters the gap between the inner end region 35A and the leading edge 20 is actively crushed by the inner end region 35A and the leading edge 20. In the embodiment shown in FIG. 8(c), the boundary 35C is also closest to the leading edge 20 on the upper surface 35 of the cutter 30. Therefore, the foreign matter is cut into smaller pieces by the leading edge 20 and the boundary 35C.

[0047] By making the angle θ2 larger than the angle θ1, the leading edge 20 can actively move the ground up foreign matter toward the trailing edge 21. If the pump casing 5 has a groove 40, the leading edge 20 can actively push the foreign matter into the groove 40. Once inside the groove 40, the foreign matter moves along the groove 40 and is released into the volute chamber 13 at the end 40b of the groove 40. The foreign matter received by the front side surface 36 of the cutter 30 is guided into the groove 40 through the front side surface 36, and is released from the groove 40 into the volute chamber 13 by the rotation of the impeller 4.

[0048] FIG. 10 is a view showing the front side of a cutter having a flat shape. FIG. 11 is a view showing the front side of a cutter bent at a predetermined angle. FIG. 12 is a view showing the front side of a cutter having a curved shape. In the embodiment shown in FIG. 10, the front side 36 of the cutter 30 has a planar shape parallel to a reference line RL extending perpendicular to the axis CL. In the embodiment shown in FIG. 11, the front side 36 extending parallel to the reference line RL has a shape that is bent partway in the rotation direction of the impeller 4 (see the arrow in FIG. 11). In the embodiment shown in FIG. 12, the front side 36 has a curved shape that extends in an arc in the rotation direction of the impeller 4 (see the arrow in FIG. 12).

[0049] The operator may select the shape of the front side surface 36 of the cutter 30 based on factors such as the material, size, and length of the foreign matter contained in the liquid. In particular, if the cutter 30 has a structure that allows it to be removed from the casing liner 11, the operator can change the cutter 30 having a different front side surface 36 as appropriate depending on the installation situation of the pump device PA.

[0050] 13(a) to 13(c) are diagrams showing the angle between the top surface of the cutter and the front side surface of the cutter. As shown in FIGS. 13(a) and 13(c), the angle θa between the top surface 35 and the front side surface 36 may be an acute angle, or as shown in FIG. 13(b), the angle θa may be a right angle (90 degrees). When the angle θa is an acute angle, the angle θa may be 45 degrees to 58 degrees. Although not shown, the angle θa may also be an obtuse angle as long as the above-mentioned effects can be achieved.

[0051] In the embodiment shown in Figure 13(c), the cutter 30 does not have a lower surface 38, and the vertical cross-sectional shape of the cutter 30 is triangular. As shown in Figures 13(a) to 13(c), the vertical cross-sectional shape of the cutter 30 may be rectangular or triangular.

[0052] In the above-described embodiment, the upper surface 35 of the cutter 30 has been described as having two regions (i.e., the inner end region 35A and the outer end region 35B), but the number of regions on the upper surface 35 of the cutter 30 is not limited to two. In one embodiment, the upper surface 35 of the cutter 30 may have regions with three or more angles (inclination angles).

[0053] The above-described embodiments have been described for the purpose of enabling a person of ordinary skill in the art to practice the present invention. Various modifications of the above-described embodiments would naturally be possible for a person skilled in the art, and the technical concept of the present invention may also be applied to other embodiments. Therefore, the present invention is not limited to the described embodiments, but should be accorded the broadest scope consistent with the technical concept defined by the claims. [Explanation of symbols]

[0054] 1 pump 2 motors 3 Rotation Axis 4 impeller 5 Pump casing 6 Mechanical seal 7 Fasteners 10 Casing body 11 Casing liner 11a Inner surface 12 Intake port 13 Volute chamber 14 Outlet 15 wings 16 Boss section 20 leading edge 21 Trailing edge 25 Tongue 30 Cutter 31 Cutter attachment part 32 Fasteners 35 Top 35A Inner end area (tip side area) 35B Outer end area (proximal end area) 35C Boundary 36 Front side 37 Rear side 38 Bottom side 40 grooves 40a beginning 40b termination

Claims

1. A pump casing capable of accommodating an impeller, the pump casing is provided with a cutter having an upper surface facing a leading edge of the impeller when the impeller is housed in the pump casing; the upper surface has at least two angled regions; the cutter protrudes from the suction port of the pump casing, The region is an inner end region arranged on the inner end side of the leading edge portion; an outer end region disposed on the outer end side of the front edge portion, A pump casing, wherein an angle between the inner end region and the leading edge portion is greater than an angle between the outer end region and the leading edge portion.

2. A pump casing capable of accommodating an impeller, the pump casing is provided with a cutter having an upper surface facing a leading edge of the impeller when the impeller is housed in the pump casing; the upper surface has at least two angled regions; the cutter protrudes from the suction port of the pump casing, A pump casing, wherein when the cutter is viewed from the axial direction of the rotation shaft of the impeller, the tip of the cutter is arranged so as to intersect the rotation shaft perpendicularly.

3. The region is an inner end region arranged on the inner end side of the leading edge portion; an outer end region disposed on the outer end side of the front edge portion, The pump casing according to claim 2 , wherein an angle between the outer end region and the leading edge portion is larger than an angle between the inner end region and the leading edge portion.

4. the upper surface has a boundary portion that divides the region into an inner end region disposed on the inner end side of the leading edge portion and an outer end region disposed on the outer end side of the leading edge portion, A pump casing as described in any one of claims 1 to 3, wherein the gap between the boundary portion and the leading edge portion is smaller than the gap between the inner end region and the leading edge portion and the gap between the outer end region and the leading edge portion.

5. The pump casing according to claim 4 , wherein the boundary portion has a curved shape that smoothly connects the inner end region and the outer end region.

6. The pump casing according to claim 4 , wherein the boundary portion has an angular shape that connects the inner end region and the outer end region at a predetermined angle.

7. The pump casing comprises: a casing body that can be disposed around the impeller; The pump casing according to any one of claims 1 to 6, further comprising: a casing liner connected to the casing body and having the cutter fixed thereto.

8. The pump casing according to claim 7 , wherein the cutter is formed from a member different from the casing liner.

9. The pump casing of claim 7 , wherein the cutter is an integral part of the casing liner.

10. The cutter is a front side surface located forward in a rotation direction of the impeller when the impeller is housed in the pump casing; a rear side surface located rearward in a rotation direction of the impeller when the impeller is housed in the pump casing, The pump casing according to any one of claims 1 to 9, wherein the front side surface and the rear side surface are connected to the top surface.

11. The pump casing according to claim 10, wherein the front side has a planar shape.

12. The pump casing according to claim 10, wherein the front side surface has a shape bent at a predetermined angle.

13. The pump casing according to claim 10, wherein the front side surface has a curved shape.

14. the pump casing has a suction port and a discharge port; The pump casing according to any one of claims 1 to 13, wherein the cutter is arranged on the opposite side of the discharge port with respect to the center of the suction port.

15. The pump casing has a groove formed on its inner surface, A pump casing according to any one of claims 1 to 14, wherein the groove is arranged adjacent to the cutter.

16. A pump casing as described in any one of claims 1 to 15, wherein the cutter is fixed to a casing liner of the pump casing.

17. An impeller and A pump comprising: a pump casing according to any one of claims 1 to 16, which houses the impeller.

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