Motor pump

Abstract

A motor pump comprises: an impeller (1); a motor rotor (2) that is fixed to the impeller (1); a motor stator (3) that is disposed adjacent to the motor rotor (2); a bearing (5) that rotatably supports the impeller (1); a pump casing (7) that accommodates the impeller (1), the motor rotor (2), the motor stator (3), and the bearing (5); and a sliding contact member (50) that is removably attached to a main plate (29) of the impeller (1) and that is provided to the center of the impeller (1). The sliding contact member (50) protrudes toward an inner wall surface (60) that is positioned inside the pump casing (7).

Description

motor pump

[0001] The present invention relates to a motor pump for transporting a liquid.

[0002] A motor pump has an impeller and an electric motor that rotates the impeller. Liquid is sucked into the impeller by the rotating impeller, and the pressure is increased by the rotation of the impeller. A motor pump is a pump that can operate without leakage because the motor and pump are integrated into a single structure, eliminating the need for a shaft seal and sealing the liquid. Such motor pumps are used to transport various types of liquids (e.g., water, chemicals, refrigerants, etc.).

[0003] International Publication No. 2022 / 201731 International Publication No. 2023 / 032366 Japanese Patent Application Laid-Open No. 2010-48162

[0004] When a motor pump starts, liquid may temporarily flow into the motor pump at a high flow rate. This flow of liquid may push the impeller of the motor pump against the wall behind the impeller, causing wear or damage to the impeller. In particular, when the motor pump sucks in liquid containing slurry (for example, liquid containing ice particles) or liquid with a high specific gravity at start-up, the impeller is pushed hard against the wall.

[0005] This phenomenon can occur not only when the motor pump is started, but also when the flow rate of the liquid changes suddenly while the motor pump is running. For example, immediately after the shutoff valve connected to the discharge port of the motor pump opens, the liquid flows into the motor pump with great force, forcing the impeller against the wall on the back side.

[0006] Therefore, the present invention provides a motor pump that can prevent the impeller from being pressed against the wall surface on the rear side thereof due to a sudden inflow of liquid that may occur at the time of start-up or during operation.

[0007] In one aspect, a motor pump is provided, comprising an impeller, a motor rotor fixed to the impeller, a motor stator arranged adjacent to the motor rotor, a bearing that rotatably supports the impeller, a pump casing that houses the impeller, the motor rotor, the motor stator, and the bearing, and a sliding member that is detachably attached to a main plate of the impeller and is provided in the center of the impeller, the sliding member protruding toward an inner wall surface located within the pump casing.

[0008] In one aspect, the motor pump further includes a center cap attached to the center of the main plate of the impeller, and the sliding contact member is detachably held by the center cap. In one aspect, the main plate has a through hole formed in its center, and the center cap is inserted into the through hole. In one aspect, the inner wall surface has a recess, and a portion of the sliding contact member is located within the recess. In one aspect, the sliding contact member is held directly by the main plate of the impeller. In one aspect, the motor pump further includes a return vane arranged on the back side of the impeller and a side plate fixed to the return vane, and the inner wall surface is a surface of the side plate facing the impeller. In one aspect, the inner wall surface is a surface of the pump casing facing the impeller.

[0009] When a motor pump starts up or operates, if liquid flows into the motor pump with force, the impeller is pushed by the flow of liquid and moves toward the inner wall surface. At this time, the sliding member attached to the back surface (main plate) of the impeller comes into contact with the inner wall surface, thereby preventing the back surface of the impeller from colliding with the inner wall surface. As a result, excessive wear and damage to the impeller can be prevented.

[0010] 1. A cross-sectional view showing an embodiment of a motor pump.

[0023] FIG. 1 is an enlarged cross-sectional view of the impeller, center cap, and sliding contact member shown in FIG. 1.

[0024] FIG. 2 is a view showing a state when the sliding contact member attached to the back surface of the impeller comes into contact with an inner wall surface.

[0025] FIG. 3 is a cross-sectional view showing another embodiment of the center cap.

[0026] FIG. 4 is a cross-sectional view showing another embodiment of the sliding contact member.

[0027] FIG. 5 is a view showing an embodiment in which the center cap shown in FIG. 4 is combined with the sliding contact member shown in FIG. 5.

[0028] FIG. 6 is a cross-sectional view showing another embodiment of the sliding contact member.

[0029] FIG. 7 is a view showing an embodiment in which the center cap shown in FIG. 4 is combined with the sliding contact member shown in FIG. 7.

[0029] FIG. 7 is a cross-sectional view showing another embodiment of the center cap.

[0030] FIG. 9 is a view showing an embodiment in which the center cap shown in FIG. 9 is combined with the sliding contact member shown in FIG. 5.

[0031] FIG. 10 is a cross-sectional view showing another embodiment of the center cap and the sliding contact member.

[0032] FIG. 11 is a view showing an embodiment in which the center cap shown in FIG. 11 is combined with a disc-shaped sliding contact member.

[0033] FIG. 12 is a cross-sectional view showing another embodiment of the center cap and the sliding contact member.

[0034] FIG. 13 is a cross-sectional view showing another embodiment of the center cap and the sliding contact member.

[0035] FIG. 14 is a cross-sectional view showing another embodiment of the center cap and the sliding contact member.

[0036] FIG. 15 is a view showing an embodiment of the inner wall surface.

[0037] FIG. 16 is a view FIG. 1 is a cross-sectional view showing an embodiment of an axial gap type motor pump.

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Fig. 1 is a cross-sectional view showing one embodiment of a motor pump. As shown in Fig. 1, the motor pump includes an impeller 1, a motor rotor 2 fixed to the impeller 1, a motor stator 3 arranged adjacent to the motor rotor 2, a bearing 5 supporting the impeller 1, and a pump casing 7 accommodating the impeller 1, the motor rotor 2, the motor stator 3, and the bearing 5. In the embodiment shown in Fig. 1, the motor stator 3 is arranged radially outward of the motor rotor 2. Such a motor pump is a radial gap type motor pump.

[0012] The motor rotor 2 and the motor stator 3 constitute an electric motor 10 for rotating the impeller 1. The motor stator 3 is connected to a power cable 4. In the embodiment shown in FIG. 1 , the motor pump is a rotary machine equipped with a permanent magnet motor, but the type of motor pump is not limited to this embodiment. In one embodiment, the motor pump may be equipped with an induction motor or a reluctance motor. When the motor pump is equipped with a permanent magnet motor, the motor rotor 2 has a plurality of permanent magnets. When the motor pump is equipped with an induction motor, the motor rotor 2 is a squirrel-cage rotor.

[0013] The pump casing 7 has a liquid suction port 12 and a liquid discharge port 15. The suction port 12 and the discharge port 15 are arranged in a straight line and are located on the suction side and the discharge side of the impeller 1. In other words, the direction in which the liquid flows into the motor pump is the same as the direction in which the liquid flows out of the motor pump. This type of motor pump is also called an in-line pump.

[0014] The pump casing 7 includes a suction casing 18 having a suction port 12, a discharge casing 19 having a discharge port 15, a cylindrical partition wall 21 disposed between the motor rotor 2 and the motor stator 3, and a stator casing 22 disposed radially outside the cylindrical partition wall 21. The cylindrical partition wall 21 and the stator casing 22 are sandwiched between the suction casing 18 and the discharge casing 19. The suction casing 18 and the discharge casing 19 are connected to each other by a plurality of through bolts (not shown). A motor stator chamber 27, which is an enclosed space, is formed between the cylindrical partition wall 21 and the stator casing 22. The motor stator 3 is disposed within the motor stator chamber 27.

[0015] The cylindrical partition wall 21 is located radially outside the impeller 1 and is disposed between the motor rotor 2 and the motor stator 3. The cylindrical partition wall 21 serves to prevent the liquid discharged from the impeller 1 from entering the motor stator chamber 27. On the other hand, the motor rotor 2 comes into contact with the liquid. This type of motor pump is also called a canned motor pump.

[0016] In the embodiment shown in FIG. 1 , the impeller 1 is a centrifugal impeller. The impeller 1 may be made by casting, or may be composed of a combination of pressed metal plates, or may be made of resin. The impeller 1 has a liquid inlet 1a, a plurality of blades 28, a main plate 29 to which the plurality of blades 28 are fixed, and a liquid outlet 1b. The liquid inlet 1a faces the suction port 12 of the pump casing 7. The plurality of blades 28 are arranged around the rotational axis of the impeller 1. A plurality of permanent magnets constituting the motor rotor 2 are held by a motor rotor holder 8, which is fixed to the impeller. The motor rotor 2 and the motor rotor holder 8 rotate integrally with the impeller 1. The relative positions of the motor rotor 2 and the motor rotor holder 8 with respect to the impeller 1 are not limited to those in the embodiment shown in FIG. 1 . Furthermore, the structure for fixing the motor rotor holder 8 to the impeller 1 is not limited to those in the embodiment shown in FIG. 1 . For example, the motor rotor holder 8 may be fixed to the impeller 1 by welding, or the motor rotor holder 8 and the impeller 1 may be an integral structure.

[0017] The motor pump of this embodiment does not have a rotating shaft to which the impeller 1 is fixed. The impeller 1 is rotatably supported by a bearing 5. The bearing 5 is a plain bearing. That is, the bearing 5 has a rotating-side bearing body 5A fixed to the motor rotor holder 8 and a stationary-side bearing body 5B fixed to the pump casing 7 (more specifically, the suction casing 18). The rotating-side bearing body 5A rotates integrally with the impeller 1, whereas the stationary-side bearing body 5B does not rotate. The bearing 5 of this embodiment is configured to be able to support both the radial load and the axial load of the impeller 1.

[0018] The pump casing 7 has a suction passage 31 that communicates with the suction port 12 and the liquid inlet 1a of the impeller 1, and a discharge passage 32 that communicates with the liquid outlet 1b of the impeller 1. The suction passage 31 and the discharge passage 32 are located inside the pump casing 7. The suction passage 31 is formed by the suction casing 18. The suction passage 31 extends from the suction port 12 of the pump casing 7 to the liquid inlet 1a of the impeller 1. The discharge passage 32 has a shape that surrounds the periphery of the impeller 1.

[0019] The motor pump has a plurality of return vanes 40 arranged on the back side of the impeller 1 and a side plate 42 fixed to these return vanes 40. The return vanes 40 are fixed to the inner surface of the discharge casing 19. The side plate 42 is arranged on the back side of the impeller 1 and is located between the impeller 1 and the discharge port 15. The discharge flow path 32 communicates with the discharge port 15 via the plurality of return vanes 40.

[0020] When the impeller 1 rotates, liquid is sucked into the motor pump through the suction port 12, flows through the suction flow path 31, and enters the impeller 1 through the liquid inlet 1a. The liquid pressurized by the rotating impeller 1 is discharged from the liquid outlet 1b of the impeller 1 to the discharge flow path 32. The pressurized liquid in the discharge flow path 32 passes through the return impeller 40 and flows to the discharge port 15, and is discharged from the motor pump through the discharge port 15.

[0021] A portion of the pressurized liquid present in the discharge flow path 32 is sent to the bearing 5 through the gap between the motor rotor holder 8 and the cylindrical partition wall 21. The liquid then flows through the gap between the rotating-side bearing body 5A and the stationary-side bearing body 5B of the bearing 5 and returns to the liquid inlet 1a of the impeller 1. When the motor pump is in operation, the liquid pressurized by the rotation of the impeller 1 pushes the impeller 1 toward the suction side, and the axial load of the impeller 1 is borne by the bearing 5.

[0022] The motor pump further includes a sliding contact member 50 detachably attached to the main plate 29 of the impeller 1. This sliding contact member 50 is disposed in the center of the impeller 1. The main plate 29 forms the back surface of the impeller 1, and the sliding contact member 50 is disposed in the center of the main plate 29. In this embodiment, the motor pump further includes a center cap 52 attached to the center of the main plate 29 of the impeller 1, and the sliding contact member 50 is held in a detachable manner by the center cap 52.

[0023] The sliding contact member 50 protrudes toward an inner wall surface 60 located inside the pump casing 7. This inner wall surface 60 is the surface of the side plate 42 fixed to the return blade 40 that faces the impeller 1. The inner wall surface 60 faces the back side of the impeller 1, i.e., the main plate 29 of the impeller 1. The center cap 52, sliding contact member 50, and impeller 1 rotate together.

[0024] FIG. 2 is an enlarged cross-sectional view of the impeller 1, center cap 52, and sliding contact member 50 shown in FIG. 1 . The main plate 29 has a through-hole 62 formed in its center, and the center cap 52 is inserted into the through-hole 62. More specifically, the center cap 52 is inserted into the through-hole 62 from the suction side of the impeller 1 and fixed to the impeller 1 by a retaining ring 65 (e.g., a C-shaped retaining ring) provided on the back side of the impeller 1. The center cap 52 has an opening 70 that opens toward the inner wall surface 60, and the sliding contact member 50 is press-fitted into this opening 70. The sliding contact member 50 protrudes toward the inner wall surface 60 from the back side of the impeller 1 (i.e., from the back side of the main plate 29). The center cap 52, the through-hole 62 of the main plate 29, and the sliding contact member 50 are aligned on the rotational axis CL of the impeller 1.

[0025] 2, there is a gap between the sliding contact member 50 and the inner wall surface 60 of the side plate 42. In other words, the sliding contact member 50 is not in contact with the inner wall surface 60 of the side plate 42 while the motor pump is operating.

[0026] When the motor pump is started or when a suction valve or a discharge valve (not shown) is opened, and liquid flows into the motor pump with force, the impeller 1 is pushed by the flow of liquid and moves toward the inner wall surface 60, as shown in Figure 3. At this time, the sliding contact member 50 attached to the back surface (main plate 29) of the impeller 1 comes into contact with the inner wall surface 60, thereby preventing the back surface of the impeller 1 from colliding with the inner wall surface 60. As a result, excessive wear and damage to the impeller 1 can be prevented.

[0027] In particular, since the sliding contact member 50 is disposed in the center where the peripheral speed of the impeller 1 is low, the sliding contact member 50 is less likely to wear when it comes into sliding contact with the inner wall surface 60. Furthermore, even if the sliding contact member 50 itself is small, it can achieve its intended purpose of preventing contact between the impeller 1 and the inner wall surface 60. Moreover, since the sliding contact member 50 is disposed in the center where the peripheral speed of the impeller 1 is low, it is not necessary to use a highly wear-resistant material for the sliding contact member 50.

[0028] The sliding contact member 50 is detachably attached to the impeller 1, and therefore no adhesive is used to secure it to the impeller 1. Therefore, the material of the sliding contact member 50 does not need to be the same material as the impeller 1, which widens the range of material options. In one embodiment, the sliding contact member 50 is made of synthetic resin. However, ceramics such as alumina may also be used as the material of the sliding contact member 50.

[0029] In this embodiment, as shown in Fig. 2, the sliding contact member 50 has a cylindrical shape with a flange portion 56. The sliding contact member 50 has an annular contact surface 57 facing the inner wall surface 60, and this contact surface 57 comes into contact with the inner wall surface 60 as shown in Fig. 3. The sliding contact member 50 has a diameter smaller than the liquid inlet 1a of the impeller 1. Furthermore, the sliding contact member 50 is located radially inward of the plurality of blades 28 of the impeller 1. The sliding contact member 50 arranged with such dimensions and at such a position can reduce the peripheral speed of the contact surface 57 when rotating integrally with the impeller 1.

[0030] As the sliding contact member 50 comes into contact with the inner wall surface 60, the sliding contact member 50 gradually wears. When the sliding contact member 50 wears beyond an allowable limit, it is replaced with a new one. That is, the motor pump is disassembled, and the sliding contact member 50 is removed from the center cap 52. Alternatively, the retaining ring 65 may be removed to remove both the center cap 52 and the sliding contact member 50 from the impeller 1, and then the sliding contact member 50 may be removed from the center cap 52. Because no adhesive is used to fix the sliding contact member 50 to the center cap 52, the sliding contact member 50 can be removed from the center cap 52.

[0031] The sliding contact member 50 and the center cap 52 may have other configurations as long as they can achieve the intended purpose of the sliding contact member 50, which is to prevent contact between the impeller 1 and the inner wall surface 60. Other embodiments of the sliding contact member 50 will be described below. In the embodiments described below, configurations that are not particularly described are the same as those in the embodiment described with reference to Figures 1 to 3, and therefore redundant description will be omitted.

[0032] 4 is a cross-sectional view showing another embodiment of the center cap 52. In FIG. 4, a retaining ring 65 is not provided, and the center cap 52 is fixed to the main plate 29 of the impeller 1 by welding or adhesive. The method of fixing the center cap 52 to the main plate 29 varies depending on the materials of the main plate 29 and the center cap 52. The sliding contact member 50 is press-fitted into an opening 70 of the center cap 52. When replacing the sliding contact member 50, the sliding contact member 50 is removed from the center cap 52.

[0033] Fig. 5 is a cross-sectional view showing another embodiment of the sliding contact member 50. In Fig. 5, the sliding contact member 50 has a cylindrical shape without a flange portion 56. The sliding contact member 50 is press-fitted into an opening 70 of a center cap 52. Fig. 6 shows an embodiment in which the center cap 52 shown in Fig. 4 is combined with the sliding contact member 50 shown in Fig. 5.

[0034] Fig. 7 is a cross-sectional view showing another embodiment of the sliding contact member 50. The sliding contact member 50 has a disk shape. The sliding contact member 50 is press-fitted into an opening 70 of a center cap 52. A contact surface 57 of the sliding contact member 50 is a circular flat surface. Fig. 8 shows an embodiment in which the center cap 52 shown in Fig. 4 is combined with the sliding contact member 50 shown in Fig. 7.

[0035] 9 is a cross-sectional view showing another embodiment of the center cap 52. The center cap 52 has a flange portion 71 located on the rear side of the impeller 1. The center cap 52 is inserted into the through-hole 62 of the main plate 29 from the rear side of the impeller 1 until the flange portion 71 contacts the main plate 29. The center cap 52 is fixed to the main plate 29 of the impeller 1 by welding or adhesive. The method of fixing the center cap 52 to the main plate 29 varies depending on the materials of the main plate 29 and the center cap 52.

[0036] The center cap 52 has a protruding portion 72 that protrudes from the flange portion 71 toward the inner wall surface 60. The sliding contact member 50 is the same as the embodiment shown in Fig. 2. The sliding contact member 50 is fitted into the protruding portion 72 of the center cap 52. Fig. 10 shows an embodiment in which the center cap 52 shown in Fig. 9 is combined with the sliding contact member 50 shown in Fig. 5.

[0037] 11 is a cross-sectional view showing another embodiment of the center cap 52 and the sliding contact member 50. The center cap 52 has a flange portion 71 located on the rear side of the impeller 1 and a retaining protrusion 75 protruding from the flange portion 71 toward the inner wall surface 60. In one embodiment, the retaining protrusion 75 is annular. The center cap 52 is inserted into the through-hole 62 of the main plate 29 from the rear side of the impeller 1 until the flange portion 56 contacts the main plate 29. The center cap 52 is fixed to the main plate 29 of the impeller 1 by welding or adhesive. The method of fixing the center cap 52 to the main plate 29 varies depending on the materials of the main plate 29 and the center cap 52.

[0038] The sliding contact member 50 is detachably held by the holding protrusion 75. The sliding contact member 50 has a ring shape. The diameter of the sliding contact member 50 is larger than the diameter of the through hole 62 of the main plate 29 but smaller than the diameter of the liquid inlet 1 a of the impeller 1. Figure 12 shows an embodiment in which the center cap 52 shown in Figure 11 is combined with a disk-shaped sliding contact member 50. The diameter of the disk-shaped sliding contact member 50 is larger than the diameter of the through hole 62 of the main plate 29 but smaller than the diameter of the liquid inlet 1 a of the impeller 1.

[0039] FIG. 13 is a cross-sectional view showing another embodiment of the center cap 52 and the sliding contact member 50. The center cap 52 has basically the same configuration as the embodiment described with reference to FIG. 7, but has a smaller opening 70 than the center cap 52 shown in FIG. 7. The sliding contact member 50 has an overall cylindrical shape and is press-fitted into the opening 70 of the center cap 52. The contact surface 57 of the sliding contact member 50 has a spherical shape. The spherical contact surface 57 reduces the contact area 57 between the sliding contact member 50 and the inner wall surface 60 of the side plate 42. As a result, the sliding contact member 50 is less susceptible to wear, and the effect of contact between the sliding contact member 50 and the inner wall surface 60 of the side plate 42 on the rotation of the impeller 1 can be minimized. In one embodiment, the center cap 52 may be fixed to the main plate 29 by welding or adhesive without providing a retaining ring 65, as in the embodiment shown in FIG. 4.

[0040] FIG. 14 is a cross-sectional view showing another embodiment of the center cap 52 and the sliding contact member 50. The basic configuration of this embodiment is the same as the embodiment described with reference to FIG. 13, but the contact surface 57 of the sliding contact member 50 has a conical shape. The conical contact surface 57 can reduce the contact area 57 between the sliding contact member 50 and the inner wall surface 60 of the side plate 42. As a result, the sliding contact member 50 is less susceptible to wear, and the effect of contact between the sliding contact member 50 and the inner wall surface 60 of the side plate 42 on the rotation of the impeller 1 can be minimized. In one embodiment, the center cap 52 may be fixed to the main plate 29 by welding or adhesive without providing a retaining ring 65, as in the embodiment shown in FIG. 4.

[0041] Figure 15 is a cross-sectional view showing another embodiment of the center cap 52 and the sliding contact member 50. The center cap 52 has basically the same configuration as the embodiment described with reference to Figure 7. The sliding contact member 50 has a disk shape as a whole and is press-fitted into an opening 70 of the center cap 52. The contact surface 57 of the sliding contact member 50 has a spherical shape. In one embodiment, as in the embodiment shown in Figure 4, the center cap 52 may be fixed to the main plate 29 by welding or adhesive without providing a retaining ring 65.

[0042] Figure 16 is a cross-sectional view showing another embodiment of the center cap 52 and the sliding contact member 50. The center cap 52 has basically the same configuration as the embodiment described with reference to Figure 7. The sliding contact member 50 has a disk shape as a whole and is press-fitted into an opening 70 of the center cap 52. The contact surface 57 of the sliding contact member 50 has a conical shape. In one embodiment, as in the embodiment shown in Figure 4, the center cap 52 may be fixed to the main plate 29 by welding or adhesive without providing a retaining ring 65.

[0043] FIG. 17 is a diagram showing one embodiment of the inner wall surface 60. The sliding contact member 50 and the center cap 52 are the same as those in the embodiment described with reference to FIG. 9. The inner wall surface 60 has a recess 80 facing the contact surface 57 of the sliding contact member 50. A portion of the sliding contact member 50, including the contact surface 57, is located within the recess 80. The contact surface 57 is located within the recess 80. This recess 80 is provided to reduce the gap between the impeller 1 and the inner wall surface 60. In other words, because a portion of the sliding contact member 50 is located within the recess 80, the impeller 1 can be positioned closer to the inner wall surface 60. Positioning the impeller 1 closer to the inner wall surface 60 can improve pump performance.

[0044] 17 , during normal operation of the motor pump, the sliding contact member 50 is not in contact with the recess 80. The axial gap G1 between the contact surface 57 of the sliding contact member 50 and the recess 80 is smaller than the axial gap G2 between the rear surface (main plate 29) of the impeller 1 and the inner wall surface 60. Therefore, when liquid flows into the impeller 1 with force, such as when the motor pump is started, the contact surface 57 of the sliding contact member 50 comes into contact with the recess 80 of the inner wall surface 60, and the impeller 1 does not come into contact with the inner wall surface 60.

[0045] The embodiment of the inner wall surface 60 having the recesses 80 shown in FIG. 17 is applicable to the embodiments described with reference to FIGS.

[0046] 2 to 17, the sliding contact member 50 is held by the center cap 52, and the sliding contact member 50 rotates integrally with the center cap 52. Therefore, wear of the sliding contact member 50 due to friction between the sliding contact member 50 and the center cap 52 does not occur.

[0047] 2 to 17, the center cap 52 is a component separate from the impeller 1, but in one embodiment, the center cap 52 and the impeller 1 may be an integral structure. For example, as shown in Fig. 18, an opening 70 may be provided in the main plate 29 of the impeller 1, and the sliding contact member 50 may be press-fitted into the opening 70 of the main plate 29. The embodiment shown in Fig. 18 is a modified example of the embodiment shown in Fig. 8, but the center cap 52 and the impeller 1 may also be an integral structure in the embodiments described with reference to Figs. 2 to 7 and 9 to 17.

[0048] The main plate 29 of the impeller 1 in the embodiment described with reference to Figures 2 to 17 has a through hole 62 into which the center cap 52 is inserted. This through hole 62 can be used to correct the rotational balance of the rotating body including the impeller 1, motor rotor 2, motor rotor holder 8, and rotating-side bearing body 5A. This correction of the rotational balance is performed as follows before assembling the motor pump.

[0049] FIG. 19 is a diagram illustrating the process of correcting the rotational balance of a rotating body including the impeller 1. The rotating body including the impeller 1, motor rotor 2, motor rotor holder 8, and rotating-side bearing body 5A is fixed to a support shaft 90. This support shaft 90 extends through a through hole 62 formed in the main plate 29 of the impeller 1. The support shaft 90 includes a first shaft 92 having a male thread 91 at its end and a second shaft 96 having a female thread 95 at its end. As shown in FIG. 19 , the male thread 91 of the first shaft 92 is inserted into the through hole 62 from one side of the impeller 1, and the male thread 91 is screwed into the female thread 95 of the second shaft 96 located on the other side of the impeller 1. The main plate 29 of the impeller 1 is sandwiched between the ends of the first shaft 92 and the second shaft 96, and is thereby held by the support shaft 90 consisting of the first shaft 92 and the second shaft 96.

[0050] The first shaft 92 is rotatably supported by a first bearing 97, and the second shaft 96 is rotatably supported by a second bearing 98. Therefore, the support shaft 90 is supported on both sides by the first bearing 97 and the second bearing 98. The rotating body including the impeller 1 is supported by the support shaft 90 that passes through the impeller 1, and the support shaft 90 is supported by the first bearing 97 and the second bearing 98 that are arranged on both sides of the impeller 1. The support shaft 90 is connected to an electric motor (not shown) and is rotated by the electric motor. The rotating body including the impeller 1 rotates integrally with the support shaft 90.

[0051] The support shaft 90 that supports the rotor including the impeller 1 is supported by a first bearing 97 and a second bearing 98 that are arranged on both sides of the rotor, so that the support shaft 90 can stably support the rotor rotating at high speed. As a result, the rotational balance correction work can be performed accurately.

[0052] The embodiment described with reference to Figure 1 is a radial gap motor pump in which the motor stator 3 is disposed radially outside the motor rotor 2, but the present invention is not limited to radial gap motor pumps. For example, the present invention can also be applied to an axial gap motor pump shown in Figure 20.

[0053] Figure 20 is a cross-sectional view showing one embodiment of an axial gap motor pump. The same components as those described with reference to Figure 1 are designated by the same reference numerals, and redundant description thereof will be omitted. In the embodiment shown in Figure 20, the motor stator 3 is disposed axially outboard of the motor rotor 2. In other words, an axial gap is formed between the motor rotor 2 and the motor stator 3.

[0054] The impeller 1 is disposed in the volute chamber 99, and the discharge port 15 is located radially outward of the impeller 1. The sliding contact member 50 attached to the main plate 29 of the impeller 1 protrudes toward an inner wall surface 60 located within the pump casing 7. This inner wall surface 60 is the inner surface of the pump casing 7 that faces the impeller 1. The inner wall surface 60 faces the back side of the impeller 1, i.e., the main plate 29 of the impeller 1. In this embodiment, the return vanes 40 shown in FIG. 1 are not provided.

[0055] When the motor pump is operating, the liquid pressurized by the rotation of the impeller 1 pushes the impeller 1 toward the suction side, and the axial load of the impeller 1 is borne by the bearing 5. When the motor pump is operating, as shown in Figure 20, there is a gap between the sliding contact member 50 and the inner wall surface 60 of the pump casing 7. In other words, when the motor pump is operating, the sliding contact member 50 is not in contact with the inner wall surface 60 of the pump casing 7.

[0056] When the motor pump is started or when a suction valve or a discharge valve (not shown) is opened, and liquid flows into the motor pump with force, the impeller 1 is pushed by the flow of liquid and moves toward the inner wall surface 60. At this time, the sliding contact member 50 attached to the back surface (main plate 29) of the impeller 1 comes into contact with the inner wall surface 60, thereby preventing the back surface of the impeller 1 from colliding with the inner wall surface 60. As a result, excessive wear and damage to the impeller 1 can be prevented.

[0057] The embodiments described with reference to FIGS. 2 to 19 are applicable to the embodiment described with reference to FIG.

[0058] 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 be obvious to a person skilled in the art, and the technical concept of the present invention may be applied to other embodiments. Therefore, the present invention is not limited to the described embodiments, but is to be interpreted in the broadest scope in accordance with the technical concept defined by the claims.

[0059] The present invention can be used in a motor pump for transporting liquid.

[0060] REFERENCE SIGNS LIST 1 impeller 1a liquid inlet 1b liquid outlet 2 motor rotor 3 motor stator 5 bearing 5A rotating side bearing body 5B stationary side bearing body 7 pump casing 8 motor rotor holding portion 10 electric motor 12 suction port 15 discharge port 18 suction casing 19 discharge casing 21 cylindrical partition wall 22 stator casing 27 motor stator chamber 28 blade 29 main plate 31 suction flow path 32 discharge flow path 40 return blade 42 side plate 50 sliding contact member 52 center cap 56 flange portion 57 contact surface 60 inner wall surface 62 through hole 65 retaining ring 70 opening 72 protrusion 75 holding projection 80 recess 90 support shaft 91 male thread 92 first shaft 95 Female thread 96 Second shaft 97 First bearing 98 Second bearing 99 Volute chamber

Claims

1. A motor pump comprising: an impeller; a motor rotor fixed to the impeller; a motor stator arranged adjacent to the motor rotor; a bearing that rotatably supports the impeller; a pump casing that houses the impeller, the motor rotor, the motor stator, and the bearing; and a sliding member that is detachably attached to a main plate of the impeller and is provided in the center of the impeller, the sliding member protruding toward an inner wall surface located within the pump casing.

2. The motor pump according to claim 1, further comprising a center cap attached to the center of the main plate of the impeller, and the sliding contact member is removably held by the center cap.

3. The motor pump according to claim 2, wherein the main plate has a through hole formed in the center thereof, and the center cap is inserted into the through hole.

4. The motor pump according to claim 1, wherein the inner wall surface has a recess, and a portion of the sliding contact member is located within the recess.

5. The motor pump according to claim 1, wherein the sliding contact member is directly held on the main plate of the impeller.

6. A motor pump according to claim 1, further comprising a return vane arranged on the rear side of the impeller and a side plate fixed to the return vane, and the inner wall surface is the surface of the side plate facing the impeller.

7. The motor pump according to claim 1, wherein the inner wall surface is a surface of the pump casing facing the impeller.

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