Sewage pump

Abstract

To provide a sewage pump capable of preventing a foreign matter from being caught in a clearance between an outer diameter end part of an impeller and a casing, and capable of preventing reduction in pump efficiency.SOLUTION: The sewage pump according to the present invention includes a rotating shaft 2 that extends in an axial direction and rotates in a circumferential direction, the axial direction being a vertical direction and a radial direction being a direction orthogonal to the axial direction, an impeller 3 that is fixed to the rotating shaft 2 and rotates to pump up pumped liquid from an upstream side to a downstream side, and a casing 4 that faces an outer end portion of the impeller 3 in the radial direction and covers the impeller 3. A portion where the pumped liquid flows into the impeller 3 is an inlet portion 10 of the impeller 3. A portion where the pumped liquid flows out from the impeller 3 is an outlet portion 7 of the impeller 3. The casing 4 includes a groove 5 extending in the axial direction in a part in the axial direction on a surface facing the impeller 3. The groove 5 is provided with a through hole 6 communicating the inside and the outside of the casing 4 at an end part on the downstream side.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a sewage pump, and more particularly to a sewage pump that can prevent foreign matter such as sand from getting caught in it. [Background technology]

[0002] Sewage pumps are used to pump wastewater. The wastewater that a sewage pump pumps often contains solid foreign matter such as sand.

[0003] An example of a conventional sewage pump is described in Patent Document 1. The sewage pump described in Patent Document 1 has a casing that forms a concentric inner circumferential surface around a main shaft, an impeller that rotates around the axis of the main shaft inside the casing, and a plurality of grooves that face the edges of the blades on the impeller on the inner circumferential surface of the casing along the absolute velocity direction of the driven fluid, which is determined by the impeller characteristics. This sewage pump allows foreign matter introduced into the grooves to pass quickly, preventing foreign matter from getting caught and ensuring smooth rotation of the impeller. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 7-35082 Summary of the Invention [Problem to be solved by the invention]

[0005] In a sewage pump, if a foreign object (such as sand) larger than the gap between the outer diameter end (outer end in the radial direction) of the impeller and the casing enters the gap, the foreign object may become trapped and prevent the foreign object from flowing out of the gap. If the pump is operated with the foreign object trapped in the gap between the outer diameter end of the impeller and the casing, the outer diameter end of the impeller and the casing may wear abnormally, leading to a decrease in pump performance. In some cases, the impeller and the casing may become stuck, and the motor, which drives the sewage pump, may be damaged by overload.

[0006] In the invention described in Patent Document 1, multiple grooves provided on the inner peripheral surface of the casing prevent foreign matter from getting caught. Generally, when grooves are provided on the inner peripheral surface of the casing, the pumped liquid flows back from the downstream side to the upstream side through the grooves, reducing pump efficiency. Conventional technologies do not fully consider this reduction in pump efficiency.

[0007] An object of the present invention is to provide a sewage pump that can prevent foreign matter from getting caught in the gap between the outer diameter end of the impeller and the casing, and can prevent a decrease in pump efficiency. [Means for solving the problem]

[0008] The wastewater pump according to the present invention comprises a rotating shaft extending in the axial direction and rotating circumferentially, the vertical direction being the axial direction and the direction perpendicular to the axial direction being the radial direction, an impeller fixed to the rotating shaft and rotating to pump the pumped liquid from the upstream side to the downstream side, and a casing facing the radially outer end of the impeller and covering the impeller. The portion where the pumped liquid flows into the impeller is the inlet portion of the impeller. The portion where the pumped liquid flows out from the impeller is the outlet portion of the impeller. The casing has a groove extending in the axial direction on a surface facing the impeller, the groove having a through hole at the downstream end that connects the inside and outside of the casing.

[0009] The sewage pump according to the present invention can also be configured as follows. That is, the sewage pump according to the present invention includes a rotating shaft extending in the axial direction and rotating circumferentially, the vertical direction being the axial direction and the direction perpendicular to the axial direction being the radial direction, an impeller fixed to the rotating shaft and rotating to pump the pumped liquid from the upstream side to the downstream side, and a casing facing the radially outer end of the impeller and covering the impeller. The portion through which the pumped liquid flows into the impeller is the inlet portion of the impeller. The portion through which the pumped liquid flows out of the impeller is the outlet portion of the impeller. The casing has a plurality of through holes between a position corresponding to the inlet portion and a position corresponding to the outlet portion. The through holes are conical in shape and connect the inside and outside of the casing. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a sewage pump that can prevent foreign matter from getting caught in the gap between the outer diameter end of the impeller and the casing, and can prevent a decrease in pump efficiency. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram showing the configuration of a sewage pump according to a first embodiment of the present invention. [Figure 2] 3 is a diagram showing a part of the inner surface of the casing, a groove, and a through hole in the first embodiment. FIG. [Figure 3] FIG. 10 is a diagram showing the configuration of a sewage pump according to a second embodiment of the present invention. [Figure 4] FIG. 10 is a diagram showing the configuration of a sewage pump according to a third embodiment of the present invention. [Figure 5] 10 is a diagram showing a part of the inner surface of the casing, a groove, and a through hole in the third embodiment. FIG. [Figure 6] FIG. 10 is a diagram showing the configuration of a sewage pump according to a fourth embodiment of the present invention. [Figure 7] 10 is a diagram showing a part of the inner surface of a casing, vertical grooves, horizontal grooves, through holes, and other through holes in Example 4. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0012] A sewage pump according to the present invention comprises an impeller and a casing that covers the outer diameter end of the impeller. The casing has a groove extending in the axial direction on a surface facing the impeller, along part of the axial direction. The groove has a through-hole that penetrates the casing at its downstream end. When foreign matter (e.g., sand) larger than the gap flows into the gap between the outer diameter end of the impeller and the casing, the sewage pump according to the present invention expels the foreign matter to the outside of the casing via the groove and the through-hole.

[0013] The wastewater pump according to the present invention may not have this groove, but may have a plurality of conical through holes penetrating the casing.

[0014] A sewage pump according to an embodiment of the present invention will be described below with reference to the drawings. In the following embodiment, an example will be described in which the foreign matter contained in the liquid pumped by the sewage pump is sand. Note that in the drawings used in this specification, the same or corresponding components are designated by the same reference numerals, and repeated description of these components may be omitted. [Example]

[0015] A sewage pump according to a first embodiment of the present invention will be described.

[0016] FIG. 1 is a diagram showing the configuration of a sewage pump 1 according to a first embodiment of the present invention. The sewage pump 1 according to this embodiment is a sewage pump having an open-type impeller. The sewage pump 1 pumps liquid from the bottom to the top of FIG. 1. That is, in FIG. 1, the upstream side is the bottom side and the downstream side is the top side. In the following description, the upstream end (the bottom end in FIG. 1) is also referred to as the upstream end, and the downstream end (the top end in FIG. 1) is also referred to as the downstream end.

[0017] The sewage pump 1 includes a rotating shaft 2, an impeller 3, and a casing 4.

[0018] The rotation shaft 2 extends in the vertical direction and is installed so as to be rotatable around the vertical direction.

[0019] Hereinafter, the extension direction of the rotating shaft 2 will be referred to as the axial direction, the rotation direction of the rotating shaft 2 will be referred to as the circumferential direction, and the radial direction of the rotating shaft 2 will be referred to as the radial direction. The axial direction is the vertical direction, i.e., the up-down direction. The radial direction is perpendicular to the axial direction.

[0020] The impeller 3 is fixed to the upstream end of the rotating shaft 2. The portion at the axial end of the impeller 3 where the pumped liquid flows into the impeller 3 is the inlet portion 10. The inlet portion 10 is located at the upstream end of the impeller 3. The portion at the axial end of the impeller 3 where the pumped liquid flows out from the impeller 3 is the outlet portion 7. The outlet portion 7 is located at the downstream end of the impeller 3.

[0021] The rotating shaft 2 and the impeller 3 form a rotating body that rotates together. As the impeller 3 rotates, it pumps the liquid from the upstream side (the lower side in Fig. 1) to the downstream side (the upper side in Fig. 1).

[0022] The casing 4 is installed so as to face the radially outer end (outer diameter end) of the impeller 3. The casing 4 covers the outer diameter end of the impeller 3 from below the impeller 3, and in the axial direction, exists below the inlet portion 10 of the impeller 3 and above the outlet portion 7 of the impeller 3. The interior of the casing 4 forms a flow path for the pumped liquid.

[0023] The casing 4 has grooves 5 extending from the upstream side to the downstream side on the surface (inner surface) facing the impeller 3. The casing 4 may have grooves 5 at a plurality of positions in the circumferential direction.

[0024] The groove 5 is provided on the surface of the casing 4 facing the impeller 3 and extends in the axial direction. The groove 5 does not extend all the way in the axial direction on the inner surface of the casing 4, but exists only in part of the axial direction. For example, one end (lower end) of the groove 5 in the axial direction is located at the upstream end (upstream end) of the casing 4, and the other end (upper end) is located at a position corresponding to the outlet 7 of the impeller 3, i.e., a position radially opposite the outlet 7 of the impeller 3. The groove 5 has a through hole 6 at its downstream end.

[0025] The through-hole 6 is provided in the groove 5 at a position corresponding to the outlet 7 of the impeller 3, and connects the inside and outside of the casing 4.

[0026] FIG. 2 is a view showing a part of the inner surface of the casing 4, the groove 5, and the through-hole 6, taken along the line AA in FIG.

[0027] As described above, the groove 5 is provided on the surface of the casing 4 facing the impeller 3, and extends in the axial direction from the upstream end of the casing 4 to a position on the casing 4 corresponding to the outlet 7 of the impeller 3. The through hole 6 is provided in the groove 5 and is located in the axial direction at a position corresponding to the outlet 7 of the impeller 3, and connects the inside and outside of the casing 4.

[0028] The sewage pump 1 of this embodiment is a sewage pump equipped with an open-type impeller 3, and has a groove 5 on the surface of the casing 4 facing the impeller 3, and a through-hole 6 in the groove 5 that connects the inside and outside of the casing 4. In the sewage pump 1 of this embodiment, when sand larger than this gap becomes stuck in the gap between the outer diameter end of the impeller 3 and the casing 4, the rotation of the impeller 3 moves the sand into the groove 5. Furthermore, the flow of the pumped liquid inside the casing 4 moves the sand that has moved into the groove 5 along the groove 5 to the through-hole 6. The sand that reaches the through-hole 6 is discharged to the outside of the casing 4 through the through-hole 6 due to the centrifugal force of the pumped liquid inside the casing 4 and the pressure difference between the inside and outside of the casing 4.

[0029] In the sewage pump 1 of this embodiment, this configuration makes it possible to prevent sand from getting caught in the gap between the outer diameter end of the impeller 3 and the casing 4 when sand larger than this gap becomes stuck in this gap.

[0030] Normally, if a groove is provided on the surface of the casing 4 facing the impeller 3, the pumped liquid inside the casing 4 will flow back through the groove from the downstream side of the impeller 3, where the pressure is high, to the upstream side, where the pressure is low, reducing the pump efficiency.

[0031] In the sewage pump 1 according to this embodiment, the grooves 5 do not extend along the entire axial direction of the inner surface of the casing 4 facing the impeller 3, but are present only along a portion of the axial direction, extending from the upstream end of the casing 4 to a position on the casing 4 corresponding to the outlet 7 of the impeller 3. The pressure is higher downstream of the outlet 7 of the impeller 3 (above the downstream end of the impeller 3) than on the upstream side (below). If the downstream end (upper end) of the grooves 5 is positioned corresponding to the outlet 7 of the impeller 3 (downstream end of the impeller 3), the grooves 5 do not reach the position of high pressure. Therefore, in the sewage pump 1 according to this embodiment, even though the casing 4 is provided with the grooves 5, it is possible to suppress backflow of the pumped liquid inside the casing 4 due to pressure, and to prevent a decrease in pump efficiency.

[0032] Furthermore, in the sewage pump 1 according to this embodiment, the through-hole 6 is provided in the groove 5 at a position corresponding to the outlet 7 of the impeller 3, and is located downstream of the impeller 3, close to the position where the pumped liquid is under high pressure. Therefore, the through-hole 6 can effectively discharge sand that has moved into the groove 5 to the outside of the casing 4 by utilizing not only the pressure difference between the inside and outside of the casing 4, but also the radial centrifugal force that is generated by the rotation of the impeller 3 and acts on the pumped liquid inside the casing 4. [Example]

[0033] A sewage pump according to a second embodiment of the present invention will be described below. The following mainly describes the differences between the sewage pump according to the second embodiment and the sewage pump according to the first embodiment.

[0034] 3 is a diagram showing the configuration of a sewage pump 1 according to a second embodiment of the present invention. Similar to the sewage pump 1 according to the first embodiment, the sewage pump 1 according to this embodiment is a sewage pump having an open impeller, and includes a rotating shaft 2, an impeller 3, and a casing 4.

[0035] The casing 4 has a plurality of through holes 9 on the surface (inner surface) facing the impeller 3. Unlike the casing 4 in the first embodiment, the casing 4 does not have grooves 5. The casing 4 may have through holes 9 at a plurality of positions in the circumferential direction.

[0036] The multiple through holes 9 are present in the casing 4 in the axial direction between a position corresponding to the inlet 10 of the impeller 3 (i.e., a position radially opposite the inlet 10 of the impeller 3) and a position corresponding to the outlet 7 of the impeller 3. Each through hole 9 communicates between the inside and outside of the casing 4. Preferably, the through holes 9 are conical in shape and gradually taper from the inner surface of the casing 4 to the outer surface of the casing 4 (i.e., the cross-sectional area gradually decreases).

[0037] The sewage pump 1 of this embodiment is a sewage pump equipped with an open-type impeller 3, and the surface of the casing 4 facing the impeller 3 is provided with a plurality of through-holes 9 that connect the inside and outside of the casing 4. In the sewage pump 1 of this embodiment, when sand larger than this gap becomes clogged in the gap between the outer diameter end of the impeller 3 and the casing 4, the rotation of the impeller 3 moves the sand to the position of the through-holes 9. Furthermore, the sand that has moved to the position of the through-holes 9 is discharged to the outside of the casing 4 through the through-holes 9 due to the centrifugal force of the pumped liquid inside the casing 4 and the flow velocity distribution of the pumped liquid inside the through-holes 9.

[0038] In the sewage pump 1 of this embodiment, this configuration makes it possible to prevent sand from getting caught in the gap between the outer diameter end of the impeller 3 and the casing 4 when sand larger than this gap becomes stuck in this gap.

[0039] In this embodiment, the through-hole 9 has a conical shape, and the cross-sectional area decreases from the inner surface of the casing 4 toward the outer surface of the casing 4. Therefore, the flow rate of the pumped liquid flowing inside the through-hole 9 gradually increases from the inner surface of the casing 4 toward the outer surface of the casing 4. Due to this flow rate distribution of the pumped liquid inside the through-hole 9, a flow of the pumped liquid is formed from the inner surface of the casing 4 toward the outer surface of the casing 4, and the sand that has moved to the position of the through-hole 9 is sucked into the through-hole 9 and discharged outside the casing 4.

[0040] Furthermore, a plurality of through holes 9 are present in the casing 4 in the axial direction between a position corresponding to the inlet 10 of the impeller 3 and a position corresponding to the outlet 7 of the impeller 3. Therefore, the through holes 9 can effectively discharge sand to the outside of the casing 4 by utilizing not only the flow generated by the flow velocity distribution of the pumped liquid inside the through holes 9, but also the radial centrifugal force generated by the rotation of the impeller 3 and acting on the pumped liquid inside the casing 4. [Example]

[0041] A sewage pump according to a third embodiment of the present invention will be described below. The following mainly describes the differences between the sewage pump according to the third embodiment and the sewage pump according to the first embodiment.

[0042] 4 is a diagram showing the configuration of a sewage pump 1 according to a third embodiment of the present invention. Similar to the sewage pump 1 according to the first embodiment, the sewage pump 1 according to this embodiment is a sewage pump having an open impeller, and includes a rotating shaft 2, an impeller 3, and a casing 4.

[0043] The casing 4 has a plurality of grooves 12 extending from the upstream side to the downstream side on the surface (inner surface) facing the impeller 3.

[0044] The grooves 12 are provided on the surface of the casing 4 facing the impeller 3 and extend in the axial direction. The grooves 12 do not extend all the way in the axial direction on the inner surface of the casing 4, but exist only in part of the axial direction. A plurality of grooves 12 exist on the casing 4 between a position corresponding to the inlet 10 of the impeller 3 and a position corresponding to the outlet 7 of the impeller 3. The plurality of grooves 12 are positioned at different axial and circumferential positions. Each of the grooves 12 has a through hole 13.

[0045] The through hole 13 is provided at the downstream end of the groove 12 and connects the inside and outside of the casing 4.

[0046] FIG. 5 is a view showing a part of the inner surface of the casing 4, the groove 12, and the through-hole 13, taken along the arrow BB in FIG.

[0047] As described above, the axial positions and circumferential positions of the multiple grooves 12 are different from one another. It is preferable that the axial position of the upstream end of each groove 12 is the same as the axial position of the downstream end of the circumferentially adjacent groove 12. It is also preferable that the axial position of the downstream end of each groove 12 is the same as the axial position of the upstream end of the circumferentially adjacent groove 12.

[0048] As described above, the through holes 13 are provided at the downstream ends of the respective grooves 12, and connect the inside and outside of the casing 4.

[0049] The sewage pump 1 of this embodiment is a sewage pump equipped with an open-type impeller 3, and is provided with a plurality of grooves 12 on the surface of the casing 4 facing the impeller 3, and each groove 12 is provided with a through-hole 13 that connects the inside and outside of the casing 4. In the sewage pump 1 of this embodiment, when sand larger than the gap between the outer diameter end of the impeller 3 and the casing 4 becomes clogged, the rotation of the impeller 3 moves the sand into the grooves 12. Furthermore, the flow of pumped liquid inside the casing 4 moves the sand that has moved into the grooves 12 along the grooves 12 to the through-holes 13. The sand that reaches the through-holes 13 is discharged to the outside of the casing 4 through the through-holes 13 due to the centrifugal force of the pumped liquid inside the casing 4 and the pressure difference between the inside and outside of the casing 4.

[0050] In the sewage pump 1 of this embodiment, this configuration makes it possible to prevent sand from getting caught in the gap between the outer diameter end of the impeller 3 and the casing 4 when sand larger than this gap becomes stuck in this gap.

[0051] In the wastewater pump 1 of this embodiment, the multiple grooves 12 do not extend all the way in the axial direction on the inner surface of the casing 4 facing the impeller 3, but are present only in part of the axial direction, and are present on the casing 4 between a position corresponding to the inlet 10 of the impeller 3 and a position corresponding to the outlet 7 of the impeller 3. Therefore, in the wastewater pump 1 of this embodiment, the grooves 12 do not reach a position of high pressure, and even if the casing 4 has grooves 12, it is possible to prevent the pumped liquid inside the casing 4 from flowing back due to pressure from the downstream side of the impeller 3 to the upstream side of the impeller 3, thereby preventing a decrease in pump efficiency.

[0052] Furthermore, in the sewage pump 1 according to this embodiment, the grooves 12 are positioned at different axial and circumferential positions, and the through holes 13 are provided at the downstream end of each groove 12. Therefore, the through holes 13 can effectively discharge sand that has moved into the grooves 12 to the outside of the casing 4 by utilizing not only the pressure difference between the inside and outside of the casing 4, but also the radial centrifugal force that is generated by the rotation of the impeller 3 and acts on the pumped liquid inside the casing 4. [Example]

[0053] A sewage pump according to a fourth embodiment of the present invention will be described below. Differences between the sewage pump according to the fourth embodiment and the sewage pump according to the first embodiment will be mainly described below.

[0054] 6 is a diagram showing the configuration of a sewage pump 1 according to a fourth embodiment of the present invention. Similar to the sewage pump 1 according to the first embodiment, the sewage pump 1 according to this embodiment is a sewage pump having an open impeller, and includes a rotating shaft 2, an impeller 3, and a casing 4.

[0055] The casing 4 has longitudinal grooves 15 that extend in the axial direction and lateral grooves 16 that extend in the circumferential direction on the surface (inner surface) facing the impeller 3. The casing 4 may have longitudinal grooves 15 and lateral grooves 16 at multiple positions in the circumferential direction.

[0056] Like the grooves 5 in Example 1, the longitudinal grooves 15 are provided on the surface of the casing 4 facing the impeller 3 and extend in the axial direction. The longitudinal grooves 15 do not extend all the way in the axial direction on the inner surface of the casing 4, but exist only in part of the axial direction. One end (lower end) of the longitudinal grooves 15 in the axial direction is located at the upstream end (upstream end) of the casing 4, and the other end (upper end) is located at a position corresponding to the outlet portion 7 of the impeller 3. The longitudinal grooves 15 have a through hole 17 at their downstream end.

[0057] The through hole 17 is provided in the longitudinal groove 15 at a position corresponding to the outlet portion 7 of the impeller 3, and connects the inside and outside of the casing 4.

[0058] The lateral groove 16 is provided on the surface of the casing 4 facing the impeller 3, and is connected to the longitudinal groove 15. The axial position of the lateral groove 16 corresponds to the outlet portion 7 of the impeller 3, and the lateral groove 16 is connected to the downstream end (downstream end) of the longitudinal groove 15, and extends from the longitudinal groove 15 on both sides in the circumferential direction. The lateral groove 16 does not extend all the way around the circumferential direction on the inner surface of the casing 4, but exists only in a part of the circumferential direction. The lateral groove 16 has two through holes 18.

[0059] The through holes 18 are provided at both circumferential ends of the lateral groove 16 and connect the inside and outside of the casing 4.

[0060] FIG. 7 is a view showing a part of the inner surface of the casing 4, the vertical groove 15, the horizontal groove 16, the through-hole 17, and the through-hole 18, and is a view taken along the arrow CC in FIG.

[0061] As described above, the longitudinal groove 15 and the lateral groove 16 are provided on the surface of the casing 4 facing the impeller 3. The longitudinal groove 15 extends in the axial direction from the upstream end of the casing 4 to a position of the casing 4 corresponding to the outlet 7 of the impeller 3. The lateral groove 16 is located in the axial direction corresponding to the outlet 7 of the impeller 3, is connected to the downstream end (downstream end) of the longitudinal groove 15, and extends from the longitudinal groove 15 to both sides in the circumferential direction. The through hole 17 is provided in the longitudinal groove 15 and is located at a position in the axial direction corresponding to the outlet 7 of the impeller 3. The through hole 18 is provided in the lateral groove 16 and is located at both ends in the circumferential direction of the lateral groove 16. The through hole 17 and the through hole 18 communicate the inside and outside of the casing 4.

[0062] The lateral grooves 16 do not extend over the entire circumferential direction on the inner surface of the casing 4, and it is preferable that the circumferential length is approximately the same as the axial length of the longitudinal grooves 15.

[0063] The axial position of the lateral groove 16 is preferably the same as the axial position of the through hole 17. That is, the through hole 17 is preferably located at the connection between the longitudinal groove 15 and the lateral groove 16. One through hole 18 is provided at each end of the lateral groove 16 in the circumferential direction.

[0064] The sewage pump 1 of this embodiment is a sewage pump equipped with an open-type impeller 3. The surface of the casing 4 facing the impeller 3 is provided with vertical grooves 15 and horizontal grooves 16, and through-holes 17 and 18, which connect the inside and outside of the casing 4, are provided in the vertical grooves 15 and horizontal grooves 16, respectively. In the sewage pump 1 of this embodiment, when sand larger than this gap becomes clogged in the gap between the outer diameter end of the impeller 3 and the casing 4, the rotation of the impeller 3 moves the sand into the vertical grooves 15. Furthermore, the flow of pumped liquid inside the casing 4 moves the sand moved into the vertical grooves 15 along the vertical grooves 15 to the through-holes 17. The sand that reaches the through-holes 17 is discharged to the outside of the casing 4 through the through-holes 17 due to the centrifugal force of the pumped liquid inside the casing 4 and the pressure difference between the inside and outside of the casing 4.

[0065] Sand that is not completely discharged from through-hole 17 moves along horizontal groove 16 to through-hole 18 due to the rotation of impeller 3 and the flow of the pumped liquid inside casing 4. The sand that reaches through-hole 18 is discharged to the outside of casing 4 through through-hole 18 due to the centrifugal force of the pumped liquid inside casing 4 and the pressure difference between the inside and outside of casing 4.

[0066] In the sewage pump 1 of this embodiment, this configuration makes it possible to prevent sand from getting caught in the gap between the outer diameter end of the impeller 3 and the casing 4 when sand larger than this gap becomes stuck in this gap.

[0067] The sewage pump 1 of this embodiment is provided with lateral grooves 16 in the casing 4, which are connected to the downstream end of the longitudinal groove 15 and extend circumferentially from the longitudinal groove 15 on both sides. The lateral grooves 16 are provided with through holes 18 at both circumferential ends. In the unlikely event that sand accumulates in the longitudinal groove 15 without being able to be completely discharged through the through holes 17 of the longitudinal groove 15, the sewage pump 1 of this embodiment can move this sand to the lateral groove 16 and discharge it from the through holes 18. Therefore, in addition to achieving the effects described in the first embodiment, the sewage pump 1 of this embodiment can more reliably prevent sand from getting caught in the gap between the outer diameter end of the impeller 3 and the casing 4.

[0068] Furthermore, the axial position of the lateral grooves 16 corresponds to the outlet portion 7 of the impeller 3, and is not located downstream of the impeller 3. This makes it possible to prevent the pumped liquid, which is under high pressure downstream of the impeller 3, from flowing back through the lateral grooves 16 to the upstream side of the impeller 3, and to prevent a decrease in pump efficiency.

[0069] The present invention is not limited to the above-described embodiments, and various modifications are possible. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to embodiments including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment. It is also possible to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to delete part of the configuration of each embodiment, or to add or replace other configurations. [Explanation of symbols]

[0070] 1...sewage pump, 2...rotating shaft, 3...impeller, 4...casing, 5...groove, 6...through hole, 7...outlet section, 9...through hole, 10...inlet section, 12...groove, 13...through hole, 15...longitudinal groove, 16...horizontal groove, 17...through hole, 18...through hole.

Claims

1. The vertical direction is the axial direction, and the direction perpendicular to the axial direction is the radial direction, a rotating shaft extending in the axial direction and rotating in a circumferential direction; an impeller fixed to the rotary shaft and rotating to pump the liquid from the upstream side to the downstream side; a casing that faces the radially outer end of the impeller and covers the impeller; Equipped with a portion where the pumped liquid flows into the impeller is an inlet portion of the impeller; a portion from which the pumped liquid flows out of the impeller is an outlet portion of the impeller, the casing has a groove extending in the axial direction in a surface facing the impeller, the groove extending in the axial direction in a part of the axial direction; The groove has a through hole at the downstream end thereof that communicates the inside and outside of the casing. A sewage pump characterized by:

2. The groove extends from the upstream end of the casing to a position corresponding to the outlet portion of the casing, and the through hole is provided at a position corresponding to the outlet portion. The wastewater pump according to claim 1.

3. the casing includes a plurality of the grooves between a position corresponding to the inlet portion and a position corresponding to the outlet portion, The plurality of grooves are positioned in the axial direction and in the circumferential direction differently from one another. The wastewater pump according to claim 1.

4. the casing has, on a surface facing the impeller, longitudinal grooves that extend in the axial direction and lateral grooves that extend in the circumferential direction, the lateral groove is connected to the downstream end of the longitudinal groove, extends from the longitudinal groove to both sides in the circumferential direction, and has through holes at both ends in the circumferential direction that communicate between the inside and the outside of the casing; The wastewater pump according to claim 2.

5. The vertical direction is the axial direction, and the direction perpendicular to the axial direction is the radial direction, a rotating shaft extending in the axial direction and rotating in a circumferential direction; an impeller fixed to the rotary shaft and rotating to pump the liquid from the upstream side to the downstream side; a casing that faces the radially outer end of the impeller and covers the impeller; Equipped with a portion where the pumped liquid flows into the impeller is an inlet portion of the impeller; a portion from which the pumped liquid flows out of the impeller is an outlet portion of the impeller, the casing has a plurality of through holes between a position corresponding to the inlet portion and a position corresponding to the outlet portion; The through hole is conical and communicates the inside and outside of the casing. A sewage pump characterized by:

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