Pumping device

Abstract

The present invention provides a pump device that can suppress the intrusion of foreign matter into the sealed box housing the rotating body that rotates the impeller. [Solution] A pump device comprising an impeller housed in a volute chamber within a pump casing, which sucks in liquid from an inlet provided in the pump casing 4 and discharges it from the volute chamber, and a seal box 5 joined to the pump casing and housing a rotating body that rotates the impeller, characterized in that a trap section is formed at the bottom of the volute chamber to suppress the flow of liquid in the direction of flowing into the liquid inflow path of the liquid flowing into an opening provided at the joint between the pump casing and the seal box.

Description

Technical Field

[0001] The present disclosure relates to a pump device.

Background Art

[0002] The pump device is, for example, a canned motor pump including a pump section and a motor section that drives the pump within the pump section. A centrifugal impeller disposed within the pump casing of the pump section rotates to impart pressure and velocity to the liquid supplied to the suction port of the pump section, and is a rotary machine that transfers the liquid. The liquid to be transferred circulates within a sealed space in which the pump section and the motor section are housed, and is configured to cool the motor within the motor section and to cool and lubricate the sliding bearings.

[0003] However, if foreign matter is mixed in the liquid to be transferred, there is a risk that the foreign matter will clog the gaps formed in the storage container that houses the pump section and the motor section that form the sealed space. For example, in the motor chamber that houses the motor section, if foreign matter clogs between the rotor that rotates the motor and the wall of the seal box that houses the stator, the rotation of the rotor may be inhibited, and as a result, the pump device may stop. In order to avoid such clogging of foreign matter, it is known to provide filters at each of the inlet and outlet of the liquid flowing through the motor chamber to prevent clogging by foreign matter (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Since foreign matter captured by foreign matter traps (e.g., filters, confinement passages, return holes, etc.) located inside the motor chamber remains within the motor chamber, if these traps become clogged with captured foreign matter, there is a risk that the captured foreign matter will scatter into the motor chamber. For this reason, regular maintenance of the foreign matter traps is necessary. If the pump system continues to operate with clogged foreign matter traps, problems such as insufficient cooling of the motor leading to burnout and insufficient lubrication of the sliding bearings resulting in abnormal wear may occur.

[0006] This disclosure was made to solve the above-mentioned problems and aims to provide a simple foreign matter trap that can prevent foreign matter from entering the sealed box containing the rotating body that rotates the impeller. [Means for solving the problem]

[0007] The pump device relating to this disclosure is The pump comprises a pump casing, an impeller housed in a volute chamber within the pump casing which draws in liquid from an inlet provided in the pump casing and discharges it from the volute chamber, and a seal box joined to the pump casing which houses a rotating body that rotates the impeller. The pump is characterized by having a trap section formed at the bottom of the volute chamber which suppresses the flow of liquid in the direction of the liquid flowing into the liquid inflow path through an opening provided at the joint between the pump casing and the seal box. [Effects of the Invention]

[0008] The pump device according to this disclosure has a simple configuration in which a trap section is formed at the bottom of the vortex chamber to suppress the flow of liquid into the liquid inflow path, thereby achieving an unprecedented and remarkable effect of suppressing the intrusion of foreign matter into the sealed box housing the rotating body that rotates the impeller. [Brief explanation of the drawing]

[0009] [Figure 1] This is an axial cross-sectional view of the pump device according to Embodiment 1. [Figure 2]This diagram illustrates the flow of the pump circulation according to Embodiment 1. [Figure 3] The cross-sectional view AA in Figure 2 illustrates the flow of the pump circulation. [Figure 4] This diagram illustrates the flow of the circulating flow inside the motor according to Embodiment 1. [Figure 5] This is an enlarged cross-sectional view of the pump section according to Embodiment 1. [Figure 6] This figure illustrates that a foreign object trap is provided in the cross-sectional view AA of Figure 2 according to Embodiment 1. [Figure 7] This is a diagram illustrating the structure of a foreign object trap according to Embodiment 1. [Figure 8] This figure illustrates that a foreign object trap is provided in the cross-sectional view AA of Figure 2 according to Embodiment 1. [Figure 9] This is an enlarged cross-sectional view of the pump section illustrating the foreign object trap according to Embodiment 2. [Figure 10] This is an enlarged cross-sectional view of the pump section illustrating the foreign object trap according to Embodiment 3. [Modes for carrying out the invention]

[0010] Hereinafter, preferred embodiments of the pump device according to the present application will be described with reference to the drawings. The same parts and components are denoted by the same reference numerals, and their detailed descriptions are omitted. Similarly, in subsequent embodiments, redundant descriptions of components denoted by the same reference numerals are omitted.

[0011] Embodiment 1. <Outline explanation of pump system configuration> Figure 1 is an axial cross-sectional view of a pump device according to Embodiment 1, and Figure 2 is a diagram illustrating the flow of liquid (pump circulation flow) within the pump device 1. The pump device 1 is a rotating machine that pumps liquids such as water by the rotation of an impeller located inside a pump casing 4. Embodiment 1 is described as a fixed-shaft canned motor pump in which, for example, a stator 13 is housed in a sealed space formed between a motor frame 40 and a seal box 5.

[0012] The pump device 1 consists of a pump unit 2 that generates a pump circulation flow 19, as indicated by the arrow in Figure 2, and a motor unit 3 that drives the pump unit 2. The pump circulation flow 19 that transfers liquid flows through the pump unit 2, and the motor unit 3 has a structure in which a motor chamber circulation flow 22 (shown in Figure 4, which will be explained later) flows inside the motor unit 3 for cooling the motor unit 3 and for cooling and lubricating the sliding bearing 10.

[0013] <Explanation of the internal chamber (liquid flow section) of the motor device> As shown in Figure 1, the impeller 6 is fixed to one end of the rotor 7 by a fixing member 31 (see Figure 3) within the inner chamber of the pump device 1, which is enclosed by the pump casing 4 and the seal box 5. The impeller 6 comprises a disc-shaped impeller main plate 29 and a plurality of blades 30 that are fixed upright on the impeller main plate 29. The plurality of blades 30 are formed as shown in Figure 3 and extend radially in the outer diameter direction of the rotor 7 from the fixing member 31. The blades 30 are formed in an arc shape to suppress losses during the conversion of liquid pressurization and acceleration. The impeller 6 may be integrally molded with the rotor 7.

[0014] The inner chamber of the pump device 1 is composed of a pump chamber 8 on the side of the impeller 6 and a motor chamber 9 on the side of the rotor 7, with the upper surface 5a of the seal box 5 as the boundary. A sliding bearing 10 for rotatably supporting the rotor 7 is fixed to the inner peripheral side of the rotor 7 in the motor chamber 9, and a shaft 11 is disposed inside the sliding bearing 10 with a gap therebetween. Since one end of the shaft 11 is supported by the shaft support 5b of the seal box 5 and the other end is supported by the shaft support 4a of the pump casing 4, the rotor 7 can rotate around the shaft 11 via the sliding bearing 10. A liquid-resistant magnet 12 is fixed to the outer peripheral portion of the rotor 7.

[0015] <Description of the stator disposed outside the liquid flow path> The stator 13 is disposed in a sealed space formed between the motor frame 40, the end cover 41, and the seal box 5 via the seal box 5 on the outer periphery of the magnet 12. The stator 13 is formed by winding a plurality of stator coils 15 around a stator core 14 laminated with electromagnetic steel sheets. The stator coil 15 is electrically connected to a power supply and a control circuit (not shown). With such a structure, the stator 13 is disposed on the outer diameter side of the seal box 5 and is isolated from the liquid in the motor chamber 9 by the seal box 5.

[0016] An annular seal member 42 is disposed between the pump casing 4 and the seal box 5. The seal member 42 prevents the liquid from flowing out of the pump device 1 through these gaps.

[0017] <Drive of the motor> A current controlled from the power supply via a control circuit energizes the stator coil 15 wound around the stator core 14, generating a rotating magnetic field that causes the rotor 7, equipped with a magnet 12, to rotate around the shaft 11. The impeller 6, which is fixed to and integrated with the rotor 7, or molded integrally with the rotor 7, rotates, transferring liquid as shown in Figure 2 and generating a pump circulation flow 19. A portion of the pump circulation flow 19 flows into the motor chamber 9, becoming a motor chamber circulation flow 22 that flows within the motor chamber 9, contributing to the cooling of the motor section 3 and the lubrication of the sliding bearing 10.

[0018] <Explanation of liquid flow 1. Pump circulation flow> The pump circulation flow 19 and its path will be explained with reference to Figures 2 and 3. When the impeller 6 rotates, liquid is drawn in from the pump casing inlet 16 and flows into the interior of the impeller 6 from the upper opening 17 of the impeller. Inside the impeller 6, the pump circulation flow 19 of liquid, which has gained energy from the rotation of the impeller 6, is sent from the side of the impeller 18 to the vortex chamber 20 surrounded by the outer circumference of the impeller 6 and the pump casing 4. By passing through the vortex chamber 20, a portion of the kinetic energy of the liquid is converted into pressure energy, becoming a swirling flow 33, and the liquid is discharged outside the pump device 1 from the pump casing outlet 21. For example, if the pump device 1 is used as a circulation pump for a hot water heating system, the hot water discharged from the pump casing outlet 21 of the pump device 1 circulates within the hot water heating system and returns to the pump casing inlet 16 again.

[0019] <Explanation of liquid flow 2. Circulating flow inside the motor> Figure 4 illustrates the flow of the motor chamber circulation flow 22. A portion of the pump circulation flow 19 flows into the motor chamber 9 through the motor chamber circulation inlet 23, which is the gap between the bottom outer circumference of the impeller 6 and the seal box 5. This liquid that flows into the motor chamber 9 is the motor chamber circulation flow 22. As indicated by the arrows of the motor chamber circulation flow 22 in Figure 4, the motor chamber circulation flow 22 passes through the motor chamber circulation inlet 23 and flows into the motor chamber space 24. Subsequently, it flows through the gap between the magnet 12, which is located on the outer circumference of the rotor 7, and the seal box 5, and flows into the motor chamber space 25. Subsequently, it is returned to the inside of the impeller 6 through the small gap between the sliding bearing 10 and the shaft 11, through which the pump circulation flow 19 flows. In this way, the motor chamber circulation flow 22 recirculates the liquid into the motor chamber 9, thereby cooling the motor section 3 and cooling and lubricating the sliding bearing 10.

[0020] <Effects of foreign objects> In the piping that constitutes the paths other than the pump device 1, there is a risk that foreign matter such as rust (iron powder) and sand may be mixed into the pump circulation flow 19. If the pump circulation flow 19 contaminated with these foreign matter flows into the motor chamber space as the motor chamber circulation flow 22, the foreign matter may clog the gap between the magnet 12 and the seal box 5, or the gap between the sliding bearing 10 and the shaft 11, hindering the rotation of the rotor 7 and potentially causing the pump device 1 to stop. Furthermore, if foreign matter clogs the motor chamber circulation inlet 23, which is the path through which the motor chamber circulation flow 22 flows into the motor chamber spaces 24 and 25, the flow rate of the incoming motor chamber circulation flow 22 will decrease, potentially leading to insufficient cooling of the motor section 3 and subsequent burnout, or insufficient lubrication of the sliding bearing 10 and subsequent abnormal wear.

[0021] <Background to the placement of foreign object trap 26> Figure 5 is an enlarged cross-sectional view of the pump section 2 of the pump device 1 according to Embodiment 1. The pump section 2 is equipped with a foreign matter trap 26 in the vortex chamber 20 outside the pump chamber 8. The pump circulation flow 19 is accelerated and pressurized by the impeller 6 and discharged from the outer circumference of the impeller 6. Most of the liquid discharged from the impeller 6 becomes a swirling flow 33 that flows through the vortex chamber 20 of the pump casing 4 and heads toward the pump casing outlet 21 as shown in Figure 3. Of this, a portion of the liquid flows into the motor chamber space 24 from the motor chamber circulation inlet 23, which is the gap between the bottom outer circumference of the impeller 6 and the seal box 5, and becomes the motor chamber circulation flow 22.

[0022] Most of the liquid flowing into the motor chamber circulation inlet 23 is due to backflow 28. That is, a portion of the liquid discharged from the outer circumference of the impeller 6 is affected by the velocity strain in the width direction of the impeller 6 or by the impact of the inner wall 35 of the pump casing 4, causing a backflow 28 to flow from the upper surface 5a of the seal box 5 towards the motor chamber circulation inlet 23. This backflow 28 results in pump losses. Therefore, in order to prevent foreign matter that may be mixed into the backflow 28 from entering the motor chamber space 24, a foreign matter trap 26 should be provided on the upper surface 5a of the seal box 5, which constitutes the bottom of the vortex chamber 20, to prevent the flow of backflow 28 that may contain foreign matter from entering the motor chamber circulation inlet 23.

[0023] <Formation location and shape of foreign object trap 26> The foreign matter trap 26 is positioned in the vortex chamber 20, which is the path of the pump circulation flow 19, and extends upward from the upper surface 5a of the seal box 5 toward the vortex chamber 20, forming an annular protrusion as shown in Figure 6. The cross-section of the protrusion of the foreign matter trap 26 is preferably triangular, as shown in Figure 5 or Figure 7. The side facing the impeller 6 (the side facing the motor chamber circulation inlet 23) is formed as a vertical wall perpendicular to the upper surface of the seal box 5, and the side facing the inner wall 35 of the pump casing 4, opposite to the impeller 6 side (the side facing the motor chamber circulation inlet 23), is an inclined wall 27 that slopes upward from the upper surface of the seal box 5 toward the vertical wall, for example, so that the annular outer diameter decreases toward the vertical wall. The inclination angle of the inclined wall is preferably an angle that can guide the inflow direction of the liquid flowing into the motor chamber circulation inlet 23 toward the flow of the liquid discharged from the vortex chamber. The annular foreign matter trap 26 having such an inclined wall 27 may be molded integrally with the seal box 5, or it may be fixed to the seal box 5 by adhesive or the like.

[0024] <Effects of Foreign Object Trap 26> The foreign matter trap 26 prevents foreign matter from entering the motor chamber space 24 from the motor chamber circulation inlet 23 by using the convex foreign matter trap 26 to suppress the flow of foreign matter that has entered the backflow 28 toward the motor chamber circulation inlet 23 that has occurred on the upper surface 5a of the seal box 5. Furthermore, by forming the side surface of the convex portion as an inclined wall 27, it is easier to guide the flow of liquid to the pump casing discharge port 21 on the outer peripheral side surface of the impeller 6 and return it to the pump circulation flow 19, thereby preventing foreign matter from entering the motor chamber space 24 from the motor chamber circulation inlet 23. Moreover, it is possible to obtain a foreign matter trap structure that does not require maintenance such as removing foreign matter clogging that is required for foreign matter traps of filters.

[0025] <Height limit for foreign object trap 26> The upper limit of the height of the foreign matter trap 26 will be explained using Figure 7. The upper limit of the foreign matter trap height 32 must be lower than the upper surface 29a of the impeller main plate 29 so as not to obstruct the pump circulation flow 19 discharged from the outer circumference of the impeller 6. The lower limit of the height should be a height that can suppress the flow in the direction of liquid flowing into the inflow path of the liquid flowing into the motor chamber circulation inlet 23, and it is desirable that the height be such that an inclined wall 27 that slopes upward from the top surface can be formed. This is expected to have the effect of guiding the backflow 28 containing foreign matter to the pump casing outlet 21 on the outer side of the impeller 6.

[0026] <Radial position of foreign object trap 26> The radial position of the foreign matter trap 26 must be outside the outer diameter of the impeller so as not to obstruct the rotation of the impeller 6. However, if the height 32 of the foreign matter trap is lower than the lower surface 29b of the impeller main plate, it may be placed inside the motor chamber circulation inlet 23, which is inside the outer diameter of the impeller 6. In this case, the effect of guiding the flow direction of the liquid flowing into the motor chamber circulation inlet 23 to the flow of the liquid discharged from the vortex chamber will be reduced, but the motor chamber circulation inlet 23 will be narrowed, which will have the effect of making it more difficult for foreign matter to enter the motor chamber. Furthermore, it is desirable that the gap dimension 36 between the outer circumference of the impeller 6 and the foreign matter trap 26 be smaller than the distance dimension 37 from the foreign matter trap 26 to the inner wall 35 of the pump casing 4. Also, if the gap dimension 36 is smaller than the gap A between the upper surface of the seal box 5 and the lower surface 29b of the impeller main plate, it is possible to avoid the accumulation of foreign matter between the outer circumference of the impeller main plate 29 and the foreign matter trap 26. This is because if the distance dimension 36 is smaller than the gap A, then any foreign objects that can pass through the gap of distance dimension 36 will be smaller than the gap A, thus reducing the likelihood of foreign objects getting stuck between the lower surface 29b of the impeller main plate and the upper surface 5a of the seal box. By setting the distance dimension 36 to a small size, only small foreign objects can pass through this gap, so they do not accumulate in the gap A and the foreign objects flow without clogging.

[0027] <Other shapes of foreign object trap 26> In the above description, the foreign matter trap 26 was formed from the seal box 5, but the foreign matter trap 26 may be formed from a separate part from the seal box 5. Also, although the foreign matter trap 26 was described as an annular wall with a triangular cross-section, the cross-section does not have to be triangular as long as it is a shape that can guide foreign matter to the pump casing discharge port 21 on the outer circumference side of the impeller 6.

[0028] Furthermore, the foreign matter trap 26 does not need to be annular; as shown in Figure 8, it may be an arc shape with a portion of the annular part cut off. In areas where the distance between the inner wall 35 of the pump casing 4 and the outer circumference of the impeller 6 is wide, particularly in the circumferential range P at the position opposite the discharge port of the pump casing 4, foreign matter will be discharged from the pump casing discharge port 21 due to the strong straight-line flow of the swirling flow 33 of the pump circulation flow 19, even without the foreign matter trap 26. Therefore, the annular shape of the foreign matter trap 26 does not need to be formed in that range P.

[0029] <Adjustment of motor chamber circulation flow 22> By adjusting the cross-sectional shape, height, and position of the foreign matter trap 26, as well as the length of the cut in the annular portion, the flow rate of the motor chamber circulation flow 22 can also be adjusted. By adjusting the flow rate of the motor chamber circulation flow 22, the functions of cooling the motor section 3, cooling and lubricating the sliding bearing 10 by the motor chamber circulation flow 22, and the function of suppressing the effects of foreign matter mixed into the motor chamber circulation flow 22 can be optimized. For example, if the cooling of the motor section 3 or the cooling and lubrication of the sliding bearing 10 is excessive, the shape and position of the foreign matter trap 26 can be adjusted to reduce the motor chamber circulation flow 22, thereby reducing the circulation speed of the liquid. This further suppresses the flow in the direction of liquid flowing into the liquid inflow path of the motor chamber circulation inlet 23, and thus further suppresses the intrusion of foreign matter.

[0030] Embodiment 2. Figure 9 is an enlarged cross-sectional view of the pump section 2 of the pump device 1 according to Embodiment 2. The pump section 2 is provided with a groove 34 that forms a recess, which is a foreign matter trap, in the vortex chamber 20 outside the motor chamber 9. As described in Embodiment 1, the pump circulation flow 19 is accelerated and pressurized by the impeller 6 and discharged from the outer circumference of the impeller 6. Most of the liquid discharged from the impeller 6 becomes a swirling flow 33 of the pump circulation flow 19 flowing through the vortex chamber 20 of the pump casing 4 and heads toward the pump casing outlet 21 (see Figure 3). However, a portion of the liquid becomes a backflow 28 and flows into the motor chamber space 24 from the motor chamber circulation inlet 23, which is the gap between the bottom outer circumference of the impeller 6 and the seal box 5, becoming the motor chamber circulation flow 22.

[0031] A groove 34 is formed on the upper surface 5a of the seal box 5 through which the backflow 28 flows, acting as a foreign matter trap. The groove 34 provides resistance to the flow of the backflow 28 compared to the smooth surface of the upper surface 5a of the seal box 5, causing the flow of the backflow 28 to become turbulent and altered, and, as in Embodiment 1, a portion of it reaches the height of the pump circulation flow 19. In addition, foreign matter mixed in the backflow 28 that collides with the side walls of the groove 34 is captured within the groove 34. Furthermore, because the groove 34 reduces the velocity of the backflow 28, relatively large foreign matter is not carried away from the backflow 28 but is captured within the groove 34. The foreign matter captured in the groove 34 is carried toward the pump casing outlet 21 by the swirling flow 33 flowing through the vortex chamber 20, which has a higher velocity and flow pressure than the pump circulation flow 19. This suppresses the intrusion of foreign matter from the motor chamber circulation inlet 23 into the motor chamber space 24. Moreover, a foreign matter trap structure is obtained that does not require maintenance such as removing foreign matter clogging, which is necessary for foreign matter traps in filters.

[0032] The groove 34, like the foreign matter trap 26, is formed in an annular shape on the upper surface 5a of the seal box 5 that forms the vortex chamber 20, and the captured foreign matter is easily discharged from the pump casing outlet 21 as the swirling flow 33 flows through the groove 34. The annular shape may also be partially missing. In other words, in areas where the distance between the inner wall 35 of the pump casing 4 and the outer circumference of the impeller 6 is wide, particularly in the circumferential range at the position facing the outlet of the pump casing 4, the foreign matter trap groove 34 is not necessary because the straight-line flow of the swirling flow 33 of the pump circulation flow 19 is strong, and the foreign matter is discharged from the pump casing outlet 21. Therefore, the annular shape of the foreign matter trap groove 34 does not need to be formed in that range (see circumferential range P in Figure 8).

[0033] Embodiment 3. Figure 10 is an enlarged cross-sectional view of the pump section 2 of the pump device 1 according to Embodiment 3. Both the foreign matter trap 26 described in Embodiment 1 and the groove 34 of the foreign matter trap described in Embodiment 2 are formed on the upper surface 5a of the seal box 5. This provides the respective effects described in Embodiment 1 and Embodiment 2, and also allows foreign matter mixed in the backflow 28 to be sifted into the groove 34 by the backflow 28 colliding with the inclined wall 27. As shown in Figure 10, a shorter distance between the foreign matter trap 26 and the groove 34 makes it easier to capture foreign matter in the groove 34, but even if there is some distance between them, the sifted-out foreign matter is pushed in the direction of the groove 34 by the backflow 28 and captured in the groove 34.

[0034] While this disclosure describes various exemplary embodiments and examples, the various features, aspects, and functions described in one or more embodiments are not limited to the application of a particular embodiment, but can be applied individually or in various combinations to the embodiments. Accordingly, countless variations not illustrated are conceivable within the scope of the technology disclosed in the specification. These include, for example, modifying, adding or omitting at least one component, or even extracting at least one component and combining it with components of other embodiments.

[0035] The various aspects of this disclosure are summarized below as an appendix.

[0036] (Note 1) Pump casing and, An impeller is housed in a volute chamber within the pump casing, which draws in liquid from an inlet provided in the pump casing and discharges it from the volute chamber. A pump device comprising a seal box joined to the pump casing and housing a rotating body that rotates the impeller, A pump device having a trap section formed at the bottom of the vortex chamber to suppress the flow of the liquid in the direction in which the liquid flows into the inflow path of the liquid that flows into the opening provided at the joint between the pump casing and the seal box. (Note 2) The pump device according to Appendix 1, characterized in that the trap portion is a convex portion. (Note 3) The pump device according to Appendix 1, characterized in that the trap portion is a recess. (Note 4) The pump device according to Appendix 1, characterized in that the trap portion has both a convex portion and a concave portion formed on the side closer to the opening. (Note 5) The pump device according to Appendix 2 or 4, characterized in that the protrusion is of a height that does not obstruct the flow of liquid discharged from the vortex chamber. (Note 6) The pump device according to Appendix 5, characterized in that the impeller is composed of a disc-shaped impeller main plate and a plurality of blades fixed upright on the impeller main plate, and the height of the protrusion is formed to be lower than the upper surface of the impeller main plate. (Note 7) The pump device according to any one of the appendices 2, 4, 5, and 6, characterized in that the wall on the opening side of the protrusion is formed vertically from the bottom of the volute chamber, and the wall on the opposite side of the opening is an inclined wall that slopes toward the vertically formed wall from the bottom of the volute chamber. (Note 8) The pump device according to Appendix 7, characterized in that the angle of the inclined wall is such that it can guide the direction of the liquid flowing into the opening to the flow of the liquid discharged from the vortex chamber. (Note 9) The pump device according to any one of the appendices 1 to 8, characterized in that the trap portion is formed in a ring shape. (Note 10) The pump device according to any one of the appendices 1 to 8, characterized in that the trap portion is formed in an arc shape. (Note 11) The pump device according to any one of the appendices 1 to 10, characterized in that the bottom of the volute chamber is formed by the seal box. [Explanation of Symbols]

[0037] 1: Pump device, 2: Pump section, 3: Motor section, 4: Pump casing, 5: Seal box, 6: Impeller, 7: Rotor, 8: Pump chamber, 9: Motor chamber, 10: Sliding bearing, 11: Shaft, 12: Magnet, 13: Stator, 14: Stator core, 15: Stator coil, 16: Pump casing inlet, 17: Impeller upper opening, 18: Impeller side, 19: Pump circulation flow, 20: Volute chamber, 21: Pump casing 22: Outlet, 23: Motor interior circulation flow, 24, 25: Motor interior space, 26: Foreign object trap, 27: Inclined wall, 28: Backflow, 29: Impeller main plate, 29a: Upper surface of impeller main plate, 29b: Lower surface of impeller main plate, 30: Blade, 31: Fixing member, 32: Foreign object trap height, 33: Swirling flow, 34: Groove, 35: Inner wall, 36: Gap dimension, 37: Distance dimension, 40: Motor frame, 41: End cover, 42: Seal member.

Claims

1. Pump casing and, An impeller is housed in a volute chamber within the pump casing, which draws in liquid from an inlet provided in the pump casing and discharges it from the volute chamber. A pump device comprising a sealed box joined to the pump casing and housing a rotating body that rotates the impeller, A pump device having a trap section formed at the bottom of the vortex chamber to suppress the flow of the liquid in the direction in which the liquid flows into the inflow path of the liquid that flows into the opening provided at the joint between the pump casing and the seal box.

2. The pump device according to claim 1, characterized in that the trap portion is a convex portion.

3. The pump device according to claim 1, characterized in that the trap portion is a recess.

4. The pump device according to claim 1, characterized in that the trap portion has both a convex portion and a concave portion formed on the side closer to the opening.

5. The pump device according to claim 2 or 4, characterized in that the protrusion is of a height that does not obstruct the flow of liquid discharged from the vortex chamber.

6. The pump device according to claim 5, characterized in that the impeller is composed of a disc-shaped impeller main plate and a plurality of blades fixed upright on the impeller main plate, and the height of the protrusion is formed to be lower than the upper surface of the impeller main plate.

7. The pump device according to claim 2 or 4, characterized in that the wall on the opening side of the protrusion is formed vertically from the bottom of the volute chamber, and the wall on the opposite side of the opening is an inclined wall that slopes toward the vertically formed wall from the bottom of the volute chamber.

8. The pump device according to claim 7, characterized in that the inclination angle of the inclined wall is an angle that can guide the inflow direction of the liquid flowing into the opening to the flow of the liquid discharged from the vortex chamber.

9. The pump device according to any one of claims 1 to 4, characterized in that the trap portion is formed in an annular shape.

10. The pump device according to any one of claims 1 to 4, characterized in that the trap portion is formed in an arc shape.

11. The pump device according to any one of claims 1 to 4, characterized in that the bottom of the vortex chamber is formed by the seal box.

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