Submerged pump

Abstract

To provide a submerged pump capable of removing liquefied gas remaining in the motor chamber. [Solution] The submerged pump 1 according to the present invention has a housing 2 that houses a rotating shaft 4 and an impeller 6. The housing includes a motor chamber 21, a pump chamber 20, a recess 24 located in the motor chamber, first passages 23, 52, 7 located below the motor 3 and communicating between the motor chamber and the pump chamber, a second passage 25 located above the motor and communicating between the motor chamber and the external space S of the housing, and a third passage 26 communicating between the recess and the external space. The third passage opens into the lowest part 24a of the inner surface of the recess. When the submerged pump is discharging the handling fluid, a portion of the handling fluid discharged from the impeller passes through the first passage and is introduced from the pump chamber to the motor chamber. The handling fluid introduced into the motor chamber passes through the motor, the second passage, and the third passage and is led out of the motor chamber to the external space.

Description

Technical Field

[0001] The present invention relates to a submerged pump.

Background Art

[0002] A submerged pump is used to extract liquefied gas (e.g., liquefied natural gas, etc.) from a storage tank in which the liquefied gas is stored (see, for example, Patent Document 1). The submerged pump is immersed in the liquefied gas stored in the storage tank. The submerged pump includes a pump chamber in which an impeller is accommodated, and a motor chamber in which a motor is accommodated. The impeller sucks and discharges the handling liquid from a suction port disposed at the lower end of the pump chamber. A part of the handling liquid discharged from the impeller is used for lubrication and cooling of the bearing, and also passes through an introduction path (e.g., bearing, etc.) and is introduced into the motor chamber, and is also used for cooling the motor.

[0003] The submerged pump is taken out of the storage tank, for example, for maintenance. When the operation of the submerged pump stops, the inside of the submerged pump is filled with the remaining liquefied gas. When the submerged pump is pulled upward above the liquid level, the liquefied gas remaining in the pump chamber is discharged from the suction port, and the liquefied gas remaining in the motor chamber passes through the introduction path and the pump chamber and is discharged from the suction port.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] A portion of the housing that partitions the motor chamber functions as a bearing bracket that holds the bearing. The bearing bracket is formed, for example, in a cylindrical shape to hold the outer ring and holder of the bearing. The housing also has a structure that allows accessories (for example, bearing vibration sensors) to be attached to the motor chamber. Thus, the housing that partitions the motor chamber has irregularities formed on it. As a result, some of the liquefied gas remaining in the motor chamber remains in the recesses formed by these irregularities. In this state, liquefied and vaporized gases leak to the outside during maintenance of the submerged pump. Much of the residual gas is flammable and toxic. Therefore, when the submerged pump is lifted above the liquid level, it is necessary to remove the liquefied gas remaining in the motor chamber (recesses).

[0006] The present invention aims to provide a submerged pump capable of removing liquefied gas remaining in the motor chamber. [Means for solving the problem]

[0007] A submerged pump in one embodiment of the present invention is a submerged pump that is immersed in a handling fluid, and comprises a motor, a rotating shaft attached to the motor, an impeller attached to the rotating shaft, and a housing that houses the rotating shaft and the impeller, wherein the housing comprises a motor chamber in which the motor is housed, a pump chamber located below the motor chamber in which the impeller is housed, a recess located in the motor chamber and concave downwards, a first flow path located below the motor and communicating with the motor chamber and the pump chamber, and above the motor The submerged pump is provided with a second flow path that is arranged in the direction and communicates with the motor chamber and the external space of the housing, and a third flow path that is communicated with the recess and the external space, wherein the third flow path opens to the lowest part of the inner surface of the recess, and when the submerged pump is discharging the handling fluid, a portion of the handling fluid discharged from the impeller passes through the first flow path and is introduced from the pump chamber to the motor chamber, and the handling fluid introduced into the motor chamber passes through the motor, the second flow path and the third flow path and is led out from the motor chamber to the external space. [Effects of the Invention]

[0008] The present invention provides a submerged pump capable of removing liquefied gas remaining in the motor chamber. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic cross-sectional view showing the usage state of the submerged pump according to the present invention. [Figure 2] Figure 1 is a cross-sectional view of a submerged pump. [Figure 3] This is a partially enlarged cross-sectional view of section A in Figure 2. [Figure 4] Figure 1 is a schematic diagram showing the flow of the liquid being handled when the submerged pump is discharging the liquid. [Figure 5] Figure 1 is a partially enlarged schematic cross-sectional view of a submerged pump, showing a portion of the flow of the liquid being handled when the submerged pump is discharging the liquid. [Figure 6] Figure 1 is a schematic diagram showing the flow of the handled fluid when the submerged pump is pulled up above the liquid surface. [Figure 7] Figure 1 is a partially enlarged schematic cross-sectional view of a submerged pump showing the flow of a portion of the handled fluid when the submerged pump is pulled up above the liquid surface. [Modes for carrying out the invention]

[0010] Embodiments of the submerged pump according to the present invention are described below. In the following description, the drawings are referenced as appropriate. In the drawings, the same reference numerals are used for the same members and elements, and redundant descriptions are omitted. In addition, the dimensional ratios of each element may be exaggerated for the sake of explanation and are not limited to the ratios shown in the drawings.

[0011] ●Submerged pump● ● Submerged pump configuration Figure 1 is a schematic cross-sectional view showing the usage state of the submerged pump according to the present invention.

[0012] The submerged pump 1 (hereinafter referred to as "pump 1") is located inside the storage tank T where the handling liquid is stored, and it pumps the handling liquid from the storage tank T to the outside. Pump 1 is immersed in the handling liquid.

[0013] "Handling liquid" refers to the liquid handled (transported) by this pump 1. Examples of handling liquids include liquefied gases such as liquefied natural gas and liquefied ammonia.

[0014] Figure 2 is a cross-sectional view of the pump 1. In the following explanation, Figure 1 will be referred to as appropriate, along with Figure 2.

[0015] This pump 1 comprises a housing 2, a motor 3, a rotating shaft 4, bearings 5, an impeller 6, and a thrust balance mechanism 7.

[0016] In the following description, the "radial direction" is the radial direction of the rotation axis 4. The "circumferential direction" is the circumferential direction of the rotation axis 4.

[0017] The housing 2 houses the motor 3, the rotation axis 4, the bearings 5, the impeller 6, and the thrust balance mechanism 7. The shape of the housing 2 is a substantially cylindrical shape along the vertical direction. The housing 2 includes a peripheral wall portion 2a, an upper wall portion 2b, a lower wall portion 2c, a partition wall portion 2d, a pump chamber 20, a motor chamber 21, two bearing brackets 22, 23, a recess 24, a lead-out hole 25, a drain hole 26, an orifice member 27, a suction port 28, a discharge flow path 29, and a discharge port (not shown; the same applies hereinafter).

[0018] In the following description, the "upstream side" is the upstream side in the flow of the handling liquid flowing inside the housing 2, and the "downstream side" is the downstream side in the flow of the handling liquid flowing inside the housing 2.

[0019] The peripheral wall portion 2a is a substantially cylindrical wall. The peripheral wall portion 2a partitions the internal space (pump chamber 20 and motor chamber 21) of the housing 2 and the external space S of the housing 2.

[0020] The "external space S" is the space outside (around) the housing 2 (this pump 1). In the present embodiment, the external space S is the internal space of the storage tank T. When this pump 1 is operating, at least the periphery of the external space S is filled with the handling liquid.

[0021] The upper wall portion 2b is a wall disposed above the peripheral wall portion 2a. The upper wall portion 2b partitions the motor chamber 21 and is disposed above the motor 3.

[0022] The lower wall portion 2c is a wall disposed below the partition wall portion 2d. The lower wall portion 2c partitions the pump chamber 20.

[0023] The partition wall 2d is located below the peripheral wall 2a and is positioned between the pump chamber 20 and the motor chamber 21. The partition wall 2d separates the pump chamber 20 and the motor chamber 21. The partition wall 2d is positioned below the motor 3. The partition wall 2d has an upper surface 2e and a retaining hole 2f (see Figure 3 for both; the same applies hereinafter). The retaining hole 2f is located in the center of the partition wall 2d and is a through hole that penetrates the partition wall 2d in the vertical direction. The partition wall 2d is an example of a partition wall in the present invention.

[0024] The pump chamber 20 houses the impeller 6. The pump chamber 20 is located in the lower half of the housing 2.

[0025] The motor room 21 houses the motor 3. The motor room 21 is located in the upper half of the housing 2. In other words, the motor room 21 is located above the pump room 20.

[0026] A portion of the upper wall 2b protrudes downward in a cylindrical shape, forming a bearing bracket 22. The bearing bracket 22 holds the bearing 51 (described later).

[0027] The bearing bracket 23 holds the bearing 52 (described later). The bearing bracket 23 has a two-stage cylindrical shape. The bearing bracket 23 has an upper part 23a and a lower part 23b (see Figure 3 for both; the same applies hereafter). The inner diameter of the upper part 23a is smaller than the inner diameter of the lower part 23b. The bearing bracket 23 is held in the partition wall 2d (holding hole 2f). The bearing bracket 23 is positioned below the motor 3. The upper part 23a protrudes upward from the partition wall 2d.

[0028] In the radial direction, a recess 24 is defined on the outer side of the bearing bracket 23 by the housing 2 (partition wall 2d, upper part 23a, and peripheral wall 2a). The shape of the recess 24 is a ring groove that is concave downwards. In a vertical view, the shape of the recess 24 is ring-shaped. That is, the recess 24 is open only upwards and has a shape that allows liquid to remain. In other words, a part of the housing 2 (near the partition wall 2d) is concave downwards, forming the recess 24. The recess 24 is located in the motor chamber 21 radially outward from the bearing bracket 23 and below the motor 3. The recess 24 has a bottom surface 24a.

[0029] The shape of the bottom surface 24a is a flat plane parallel to the horizontal direction. The bottom surface 24a is located at the lowest point of the recess 24. The bottom surface 24a is formed by the upper surface 2e of the partition wall portion 2d.

[0030] The outlet hole 25 is a through-hole that penetrates the peripheral wall portion 2a in the radial direction. The outlet hole 25 communicates with the motor chamber 21 and the external space S of the housing 2. The outlet hole 25 is located at the upper part of the peripheral wall portion 2a. In the vertical direction, the outlet hole 25 is located above the motor 3. The outlet hole 25 is an example of a second flow path in the present invention.

[0031] Figure 3 is a partially enlarged schematic cross-sectional view of section A in Figure 2. In the following explanation, Figures 1 and 2 will be referred to together with Figure 3 as appropriate.

[0032] The drain hole 26 is a through-hole that penetrates the partition wall 2d. The drain hole 26 opens to the upper surface 2e (bottom surface 24a of the recess 24) of the partition wall 2d and to the outer peripheral surface 2g of the partition wall 2d. That is, the drain hole 26 is located in the partition wall 2d and communicates with the recess 24 (motor chamber 21) and the external space S. In radial view, the shape of the drain hole 26 is approximately "L-shaped". The drain hole 26 comprises a first drain hole 26a, a second drain hole 26b, and two openings 26c and 26d. The cross-sectional area "A1" of the drain hole 26 is smaller than the cross-sectional area "A2" of the outlet hole 25. The "cross-sectional area" is the area of ​​a virtual cross-section (cross-section) perpendicular to the direction of flow of the liquid being handled inside each hole. The drain hole 26 is an example of a third flow path in the present invention.

[0033] The first drain hole 26a is the portion of the drain hole 26 that runs vertically. The second drain hole 26b is the portion of the drain hole 26 that runs radially (horizontally). The second drain hole 26b is located downstream (at the lower end) of the first drain hole 26a and is adjacent to the first drain hole 26a. The opening 26c opens into the bottom surface 24a and is located at the upstream end (upper end) of the first drain hole 26a. The opening 26d opens into the peripheral wall portion 2a and is located at the downstream end (outer radial end) of the second drain hole 26b.

[0034] The orifice member 27 restricts the flow rate of the liquid being handled through the drain hole 26. The orifice member 27 is, for example, a plug that is screwed into the drain hole 26 (first drain hole 26a). The shape of the orifice member 27 is, for example, cylindrical. The orifice member 27 has a restricting hole 27a. The orifice member 27 is detachably attached to the 26c end of the drain hole 26.

[0035] The aperture hole 27a is a through hole that penetrates the orifice member 27 in the vertical direction. The aperture hole 27a communicates with the recess 24 (motor chamber 21) and the portion of the drain hole 26 downstream of the aperture hole 27a. The cross-sectional area "A3" of the aperture hole 27a is smaller than the cross-sectional area "A1" of the drain hole 26. Here, the ratio of the cross-sectional area "A3" of the aperture hole 27a to the cross-sectional area "A2" of the outlet hole 25 (A3 / A2) is preferably "0.3" or less, and more preferably designed to be "0.1" or less. The aperture hole 27a is an example of a communication passage in the present invention.

[0036] In the following explanation, the drawing primarily referred to will be Figure 2. The lower part of the lower wall 2c is tapered in diameter, forming the suction port 28. That is, the suction port 28 is located at the lower end of the housing 2.

[0037] The discharge channel 29 is the channel through which the liquid being handled, discharged from the impeller 6, flows. The discharge channel 29 is located inside the peripheral wall 2a and the partition wall 2d.

[0038] Motor 3 is driven under predetermined operating conditions to rotate the impeller 6. Motor 3 is a known motor comprising a rotor 31 and a stator 32.

[0039] The rotating shaft 4 rotates due to the rotation of the motor 3 and transmits rotational power to the impeller 6. The shape of the rotating shaft 4 is cylindrical, extending in the vertical direction. The rotating shaft 4 is attached to the rotor 31. The lower half 4a of the rotating shaft 4 extends downward from the motor 3 into the pump chamber 20.

[0040] The bearing 5 rotatably supports the rotating shaft 4. The bearing 5 is, for example, a rolling bearing. The bearing 5 comprises bearings 51 and 52. Bearing 51 is held in the bearing bracket 22. Bearing 52 is held in the upper part 23a of the bearing bracket 23.

[0041] The impeller 6 is attached to the lower half 4a of the rotating shaft 4 and discharges the liquid being handled, which is drawn in from below, radially outward. The impeller 6 is housed in the pump chamber 20 and is positioned above the suction port 28 in the vertical direction.

[0042] The thrust balance mechanism 7 reduces the thrust force (the force pushing the impeller 6 downwards) caused by the pressure difference between the downward and upward sides of the impeller 6. The thrust balance mechanism 7 is a known thrust balance mechanism used in known pumps. The thrust balance mechanism 7 is mounted on the rotating shaft 4 and is housed in the lower part 23b of the bearing bracket 23.

[0043] ● Flow of the fluid being handled in a submerged pump Next, the flow of the liquid being handled in pump 1 when pump 1 is discharging the liquid (when pump 1 is operating) and when pump 1 is pulled up above the liquid surface will be described below. Figures 1 to 3 will be referred to as appropriate in the following description.

[0044] ● Flow of the fluid being handled when the submerged pump is discharging the fluid Figure 4 is a schematic diagram showing the flow of the liquid being handled when the pump 1 is discharging the liquid. Figure 5 is a partially enlarged schematic cross-sectional view of the pump 1 showing a portion of the flow of the liquid being handled when the pump 1 is discharging the liquid.

[0045] When the pump 1 is discharging the liquid being handled (when the pump 1 is operating), the liquid being handled in the external space S (the internal space of the storage tank T) is drawn into the pump 1 through the suction port 28 (flow F1). The liquid being handled that is drawn into the suction port 28 is drawn into the impeller 6 and discharged to the downstream side of the pump chamber 20 from the impeller 6. Most of the liquid being handled that is discharged from the impeller 6 is discharged through the discharge channel 29 to the destination (not shown) from the discharge port (flow F2).

[0046] A portion of the fluid discharged from the impeller 6 passes through the thrust balance mechanism 7 and the bearing 52 inside the bearing bracket 23 and is introduced into the motor chamber 21 (flow F3). That is, the bearing bracket 23, the thrust balance mechanism 7, and the bearing 52 form a flow path that introduces a portion of the fluid discharged from the impeller 6 from the pump chamber 20 to the motor chamber 21. The bearing bracket 23, the thrust balance mechanism 7, and the bearing 52 are an example of the first flow path in the present invention. At this time, the fluid functions as a lubricant and coolant for the bearing 52.

[0047] Most of the fluid being handled, introduced into the pump chamber 20, passes through the motor 3 and is introduced upwards (flow F4). At this time, the fluid being handled functions as a coolant for the motor 3. After passing through the motor 3, the fluid being handled passes through the outlet hole 25 and is discharged into the external space S (flow F5).

[0048] A portion of the liquid being handled, introduced into the pump chamber 20, passes through the recess 24, the throttling hole 27a of the orifice member 27, and the drain hole 26, and is led out to the external space S (flow F6).

[0049] A portion of the fluid handled that flows through the discharge channel 29 passes through the bearing 51 and is introduced into the motor chamber 21 (flow F7). At this time, the fluid handled functions as a lubricant and coolant for the bearing 51.

[0050] Thus, flows F1, F3, F4, and F5 form a circulating flow Fc that lubricates and cools the bearing 52 and the motor 3. On the other hand, flow F6 does not contribute to the cooling of the motor 3 and is a flow that does not occur in conventional pumps that do not have a drain hole 26 (hereinafter referred to as "conventional pumps"). If the flow rate of flow F6 becomes large and the circulating flow Fc is obstructed or greatly disturbed by flow F6, the performance of this pump 1 will decrease. Therefore, flow F6 is essentially an unnecessary flow. For this reason, the flow rate of flow F6 (in other words, the flow rate of the handled fluid flowing through the drain hole 26 restricted by the throttling hole 27a "Q1") is designed to be sufficiently smaller than the flow rate of the circulating flow Fc (in other words, the flow rate of flow F5 "Q2").

[0051] As mentioned above, the cross-sectional area "A3" of the throttling hole 27a is smaller than the cross-sectional area "A1" of the drain hole 26 and the cross-sectional area "A2" of the outlet hole 25. The cross-sectional area "A1" of the drain hole 26 is smaller than the cross-sectional area "A2" of the outlet hole 25. Therefore, the internal resistance of the throttling hole 27a (drain hole 26) is greater than the internal resistance of the outlet hole 25. As a result, the flow rate "Q1" of the handled fluid (flow F6) flowing through the drain hole 26, which is restricted by the throttling hole 27a, is smaller than the flow rate "Q2" of the handled fluid (flow F5) flowing through the outlet hole 25. This pump 1 uses this difference in internal resistance to limit the flow rate "Q1". Specifically, the difference in internal pipe resistance is designed such that the ratio of flow rate "Q1" to flow rate "Q2" (Q1 / Q2) is preferably "0.1" or less (for example, "0.01" to "0.05"). As a result, in this pump 1, the flow rate "Q1" is suppressed to an acceptable range that does not degrade the performance of this pump 1. Therefore, even if flow F6 occurs during the operation of this pump 1, the performance of this pump 1 does not degrade (even if the performance does degrade, the degradation is suppressed to an acceptable range).

[0052] ● Flow of the handled fluid when the submerged pump is lifted above the liquid level Figure 6 is a schematic diagram showing the flow of the handled liquid when the pump 1 is pulled up above the liquid surface. Figure 7 is a partially enlarged schematic cross-sectional view of the pump 1 showing the flow of a portion of the liquid being handled when the pump 1 is pulled up above the liquid surface.

[0053] Pump 1 is removed from the storage tank T, for example, for maintenance. At this time, the operation of pump 1 is stopped. When the operation of pump 1 is stopped, the inside of pump 1 is filled with residual handling fluid. When pump 1 is lifted above the liquid level, the handling fluid remaining in the pump chamber 20 is discharged downward (to the external space S) from the suction port 28 (flow F11). Also, the handling fluid remaining in the motor chamber 21 is discharged into the pump chamber 20 through the bearing bracket 23, bearing 52, and thrust balance mechanism 7 (flow F12), and then discharged downward (to the external space S) through the suction port 28 (flow F11) after passing through the pump chamber 20.

[0054] As mentioned above, the recess 24 is recessed downwards. Therefore, some of the handling fluid remaining in the motor chamber 21 remains in the recess 24. The handling fluid remaining in the recess 24 is discharged into the external space S through the throttling hole 27a and the drain hole 26 (flow F13). In this way, when the pump 1 is pulled up above the liquid level, the handling fluid remaining in the motor chamber 21 (recess 24) is removed. Therefore, during maintenance of the pump 1, the handling fluid and its vaporized gas do not leak to the outside of the pump 1.

[0055] Thus, the pump 1 does not have an opening / closing mechanism that closes the drain hole 26 when the pump 1 is operating and opens the drain hole 26 only when discharging the handling liquid remaining in the recess 24. In other words, in the pump 1, the drain hole 26 is always in communication with the recess 24 and the external space S. The handling liquid of the pump 1 is mostly cryogenic liquefied gas. When the pump 1 is operating, the pressure of the handling liquid introduced into the motor chamber 21 is increased by the impeller 6. Therefore, if an opening / closing mechanism for opening and closing the drain hole 26 were to be attached to the pump 1, the mechanism would need to be liquid-tight to prevent leakage of the cryogenic and high-pressure handling liquid into the external space S, and to operate normally and reliably at cryogenic temperatures. Consequently, the manufacture of such an opening / closing mechanism is not easy, and the man-hours and processing required to attach the mechanism to the pump 1 would be considerable, resulting in high manufacturing costs. In this pump 1, the handling fluid remaining in the recess 24 can be discharged simply by forming a through hole in the housing 2 (partition wall 2d) that communicates with the recess 24. Therefore, this pump 1 does not require any additional work or processing for the installation of an opening / closing mechanism. As a result, in this pump 1, the flow rate "Q1" of the flow F6 when the pump 1 is operating is limited, so there is no decrease in the performance of the pump 1, and the handling fluid remaining in the motor chamber 21 is easily discharged into the external space S without the need for the aforementioned opening / closing mechanism.

[0056] Furthermore, the orifice member 27 is detachable from the drain hole 26. Therefore, the internal resistance of the throttling hole 27a (drain hole 26) (flow rate "Q1" of flow F6) can be easily adjusted simply by replacing the orifice member 27 with one of a different size throttling hole 27a.

[0057] ●Summary According to the embodiment described above, the pump 1 comprises a bearing bracket 23, a recess 24, an outlet hole 25, a drain hole 26, a bearing 52, and a thrust balance mechanism 7. The recess 24 is located in the motor chamber 21. The shape of the recess 24 is a downwardly concave ring groove. The bearing bracket 23, the bearing 52, and the thrust balance mechanism 7 are located below the motor 3 and function as a first flow path communicating between the motor chamber 21 and the pump chamber 20. The outlet hole 25 is located above the motor 3 and functions as a second flow path communicating between the motor chamber 21 and the external space S. The drain hole 26 functions as a third flow path communicating between the recess 24 and the external space S. The drain hole 26 opens into the bottom surface 24a, which is the lowest part of the inner surface of the recess 24. When the pump 1 is discharging the handling fluid (operating), a portion of the handling fluid discharged from the impeller 6 is introduced into the motor chamber 21 through the thrust balance mechanism 7 and the bearing 52 (first flow path) inside the bearing bracket 23. The handling fluid introduced into the motor chamber 21 is then discharged from the motor chamber 21 to the external space S through the motor 3, the outlet hole 25, and the drain hole 26. With this configuration, the drain hole 26 is always in communication with the recess 24 and the external space S. When the pump 1 is operating, at least the flow F5 in the outlet hole 25 is ensured, and the circulating flow Fc is also ensured. Furthermore, when the pump 1 is pulled up above the liquid level, any handling fluid remaining in the motor chamber 21 (recess 24) is removed. Therefore, during maintenance of the pump 1, the handling fluid and its vaporized gases do not leak to the outside of the pump 1.

[0058] Furthermore, according to the embodiment described above, the flow rate "Q1" of flow F6 is smaller than the flow rate "Q2" of flow F5. With this configuration, it is easy to secure the circulating flow Fc, and the deterioration of the performance of the pump 1 is suppressed.

[0059] Furthermore, according to the embodiment described above, the ratio of the flow rate "Q1" of flow F6 to the flow rate "Q2" of flow F5 (Q1 / Q2) is designed to be "0.1" or less. With this configuration, the flow rate "Q1" is suppressed to within an acceptable range that does not degrade the performance of the pump 1. Therefore, even if flow F6 occurs during the operation of the pump 1, the performance of the pump 1 will not degrade (even if the performance does degrade, the degradation will be suppressed to an acceptable range).

[0060] Furthermore, according to the embodiments described above, the housing 2 is equipped with an orifice member 27. The orifice member 27 is detachably attached to the drain hole 26 and restricts the flow rate of the drain hole 26. With this configuration, the internal resistance of the drain hole 26 (flow rate "Q1" of flow F6) can be easily adjusted by attaching or detaching the orifice member 27.

[0061] Furthermore, according to the embodiments described above, the orifice member 27 is provided with a throttling hole 27a that communicates with the pump chamber 20 and the drain hole 26. The cross-sectional area of ​​the throttling hole 27a is smaller than the cross-sectional area of ​​the drain hole 26. With this configuration, the internal resistance of the throttling hole 27a (drain hole 26) (flow rate "Q1" of flow F6) can be easily adjusted simply by replacing the orifice member 27 with an orifice member 27 having a throttling hole 27a of a different size.

[0062] Furthermore, according to the embodiment described above, the housing 2 includes a partition wall 2d that separates the pump chamber 20 and the motor chamber 21. The recess 24 and the drain hole 26 are located in the partition wall 2d. With this configuration, the drain hole 26 can be formed simply by forming a through hole in the partition wall 2d. In other words, the formation of the drain hole 26 does not require the installation of an opening / closing mechanism or complex processing.

[0063] ●Other embodiments In this invention, the pump 1 may be housed in a cylindrical pump column located in the internal space of the storage tank T.

[0064] Furthermore, in the present invention, the configuration of the first flow path (bearing bracket 23, bearing 52, and thrust balance mechanism 7) is not limited to this embodiment.

[0065] Furthermore, in the present invention, the number of recesses 24 is not limited to "1". In this case, the housing 2 may be provided with a drain hole 26 for each recess 24.

[0066] Furthermore, in the present invention, the position of the recess 24 is not limited to the radially outward direction of the bearing bracket 23.

[0067] Furthermore, in the present invention, the housing 2 may be provided with a flow path (outlet flow path) located inside the housing 2 instead of the outlet hole 25. In this case, the outlet flow path communicates with the motor chamber 21 and the external space S. The outlet flow path is an example of a second flow path in the present invention.

[0068] Furthermore, in the present invention, the number of outlet holes 25 is not limited to "1".

[0069] Furthermore, in the present invention, the number of drain holes 26 is not limited to "1".

[0070] Furthermore, the shape of the drain hole 26 in a radial view is not limited to an "L" shape. That is, for example, the second drain hole 26b does not have to be arranged along the radial direction. That is, for example, the second drain hole 26b may be inclined with respect to the radial direction such that the opening 26d is at the lowest end of the drain hole 26.

[0071] Furthermore, in the present invention, the aperture hole 27a is not limited to a through hole. That is, for example, the aperture hole 27a may be formed by a groove arranged on the outer circumferential surface of the orifice member 27.

[0072] Furthermore, in the present invention, if the pipe resistance of the drain hole 26 exceeds the required value, the housing 2 does not need to be equipped with the orifice member 27.

[0073] Furthermore, in the present invention, the orifice member 27 may be attached to the end of the drain hole 26 on the opening 26d side.

[0074] Furthermore, in the present invention, the ratio of flow rate "Q1" to flow rate "Q2" is not limited to "0.1" or less, as long as the flow F6 does not significantly disturb the circulating flow Fc (i.e., the performance degradation of the pump 1 is kept within an acceptable range).

[0075] Furthermore, in the present invention, the number of impellers 6 is not limited to "1".

[0076] ●Embodiments of the present invention● Next, embodiments of the present invention as understood from the embodiments described above will be described below, with reference to the terms and reference numerals described in each embodiment.

[0077] A first embodiment of the present invention is a submerged pump (e.g., submerged pump 1) immersed in a handling fluid, comprising: a motor (e.g., motor 3); a rotating shaft (e.g., rotating shaft 4) attached to the motor; an impeller (e.g., impeller 6) attached to the rotating shaft; and a housing (e.g., housing 2) housing the rotating shaft and the impeller, wherein the housing comprises: a motor chamber (e.g., motor chamber 21) housing the motor; a pump chamber (e.g., pump chamber 20) located below the motor chamber and housing the impeller; a recess (e.g., recess 24) located in the motor chamber and concave downwards; and a first flow path (e.g., bearing bracket 23, bearing 52) located below the motor and communicating with the motor chamber and the pump chamber. The submerged pump comprises a thrust balance mechanism 7), a second flow path (e.g., outlet hole 25) positioned above the motor and communicating with the motor chamber and the external space of the housing (e.g., external space S), and a third flow path (e.g., drain hole 26) communicating with the recess and the external space, wherein the third flow path opens to the lowest part of the inner surface of the recess (e.g., bottom surface 24a), and when the submerged pump is discharging the handling fluid, a portion of the handling fluid discharged from the impeller passes through the first flow path and is introduced from the pump chamber to the motor chamber, and the handling fluid introduced into the motor chamber passes through the motor, the second flow path, and the third flow path and is led out from the motor chamber to the external space. With this configuration, when the pump is raised above the liquid level, any remaining liquid in the motor chamber (recess) is removed.

[0078] A second embodiment of the present invention is a submerged pump in which, in the first embodiment, the flow rate of the third channel (e.g., flow rate "Q1") is smaller than the flow rate of the second channel (e.g., flow rate "Q2"). This configuration makes it easy to ensure circulating flow and suppresses the degradation of the pump's performance.

[0079] A third embodiment of the present invention is a submerged pump in which, in the second embodiment, the ratio of the flow rate of the third channel to the flow rate of the second channel is 0.1 or less. With this configuration, the performance of the pump will not deteriorate even if a flow occurs while the pump is operating.

[0080] A fourth embodiment of the present invention is a submerged pump in which, in the second embodiment, the housing comprises an orifice member (for example, an orifice member 27) that is detachably attached to the third flow path and restricts the flow rate of the third flow path. With this configuration, the internal resistance of the drain hole can be easily adjusted by attaching or detaching the orifice member.

[0081] A fifth embodiment of the present invention is a submerged pump in which, in the fourth embodiment, the orifice member comprises a communication passage (e.g., a throttling hole 27a) communicating with the pump chamber and the third flow path, wherein the cross-sectional area of ​​the communication passage (e.g., cross-sectional area "A3") is smaller than the cross-sectional area of ​​the third flow path (e.g., cross-sectional area "A1"). With this configuration, the internal resistance of the diaphragm (drain hole) can be easily adjusted simply by replacing orifice members with different diaphragm sizes.

[0082] A sixth embodiment of the present invention is a submerged pump in which, in the first embodiment, the housing comprises a partition wall (for example, partition wall portion 2d) separating the pump chamber and the motor chamber, and the recess and the third flow path are arranged in the partition wall. With this configuration, drain holes can be formed simply by creating through holes in the partition wall. [Explanation of symbols]

[0083] 1. Submerged pump 2 cabinets 2d Partition wall (partition wall) 20 Pump Room 21 Motor Room 23. Bearing bracket (first flow path) 24 recesses 24a Bottom (part) 25 Outlet hole (second channel) 26 Drain hole (third channel) 27 Orifice component 27a Aperture opening (communication passage) 3 motors 4 rotation axes 52 Bearing (first flow path) 6 impellers 7. Thrust balance mechanism (first channel) S External space

Claims

1. A submerged pump that is immersed in the handling fluid, Motor and, A rotating shaft attached to the motor, An impeller attached to the aforementioned rotating shaft, A housing that houses the rotating shaft and the impeller, It has, The aforementioned enclosure is A motor chamber in which the motor is housed, A pump chamber is located below the motor chamber and houses the impeller, Arranged in the motor chamber, with a recessed area facing downwards, A first flow path is positioned below the motor and communicates with the motor chamber and the pump chamber, A second flow path is positioned above the motor and communicates with the motor chamber and the external space of the housing, A third channel communicating with the recess and the external space, Equipped with, The third channel opens to the portion of the inner surface of the recess that is located in the lowest direction, When the submerged pump is discharging the fluid being handled, A portion of the fluid being handled, discharged from the impeller, passes through the first passage and is introduced from the pump chamber to the motor chamber. The fluid being handled, introduced into the motor chamber, passes through the motor, the second flow path, and the third flow path, and is then led out of the motor chamber to the external space. Submerged pump.

2. The flow rate of the third channel is smaller than the flow rate of the second channel. The submerged pump according to claim 1.

3. (Further restricting the relationship between flow rate) The ratio of the flow rate in the third channel to the flow rate in the second channel is 0.1 or less. The submerged pump according to claim 2.

4. The aforementioned enclosure is An orifice member that is detachably attached to the third flow path and restricts the flow rate of the third flow path, Equipped with, The submerged pump according to claim 2.

5. The orifice member is, A connecting passage that communicates with the pump chamber and the third flow path, Equipped with, The cross-sectional area of ​​the aforementioned passage is smaller than the cross-sectional area of ​​the third flow path. The submerged pump according to claim 4.

6. The aforementioned enclosure is A partition wall separating the pump room and the motor room, Equipped with, The recess and the third flow channel are arranged in the partition wall. The submerged pump according to claim 1.

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