Submersible device

Abstract

To simplify a structure of a submersible device related to sealing of a shaft of a motor.SOLUTION: A submersible device (submersible pump 10) comprises: an impeller 21 to be submerged in water; a motor 31 comprising a shaft 313 which has a first end part 314 connected to the impeller; a casing (motor casing 32) comprising a partition wall (bottom part 323) in which a through hole 324 penetrated by the shaft is formed; a mechanical seal 6 for sealing the shaft by sucking air in the casing between sliding surfaces 611 and 621 while the shaft is rotating; and an electric cable (power supply cable 4) which has a first end 41 located in the casing, and a second end 42 located in the atmosphere outside the casing. The electric cable guides the air having flowed into the electric cable from the second end, into the casing. The casing supplies the air having flowed into the casing through the electric cable, to the sliding surfaces of the mechanical seal through the through hole.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The technology disclosed herein relates to underwater equipment.

Background Art

[0002] Patent Document 1 describes a shaft sealing device for an underwater pump. The shaft sealing device includes a mechanical seal that seals the shaft of a motor. The mechanical seal sucks air between the sliding surface of the rotating ring and the sliding surface of the stationary ring during the rotation of the shaft.

[0003] The shaft sealing device has a lower space. The lower space is located between the bearing and the through-hole of the housing within the housing of the motor. The bearing rotatably supports the shaft. The lower space is isolated from the motor by the bearing. The shaft is inserted through the through-hole. The lower space communicates with the atmospheric space via a pipe. The air that flows into the lower space through the pipe is supplied to the mechanical seal through the through-hole.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The above-described shaft sealing device deliberately forms a lower space in the housing and connects a pipe dedicated to air supply to the lower space only for supplying air to the mechanical seal. The above-described shaft sealing device complicates the structure of the underwater equipment.

[0006] The technology disclosed herein simplifies the structure of an underwater equipment related to the shaft sealing of the shaft of a motor.

Means for Solving the Problems

[0007] In conventional underwater devices, the casing that houses the motor was sealed. The sealed casing not only prevents water from entering but also prevents air from entering. When air enters the casing, the amount of moisture in the casing increases due to the moisture in the air, which has an adverse effect on the insulation performance of the motor.

[0008] The underwater device disclosed herein allows air to flow into the casing. The air that has passed through the inside of the casing is supplied between the sliding surfaces of the mechanical seal. Since the air passes through the inside of the casing, the amount of moisture in the casing does not increase. It is possible to suppress an adverse effect on the insulation performance of the motor. Further, since air is allowed to flow into the casing, the structure of the underwater device including the structure of the casing is simple.

[0009] Specifically, the underwater device disclosed herein includes an impeller immersed in water, a motor having a shaft with a first end connected to the impeller, a casing that houses the motor, the casing having a partition wall in which a through hole through which the shaft passes is formed, a mechanical seal that is interposed between the partition wall and the shaft outside the casing and sucks air in the casing between the sliding surfaces to seal the shaft during rotation of the shaft, an electric cable having a first end located inside the casing and a second end located in the atmosphere outside the casing, and the electric cable guides the air that has flowed into the electric cable from the second end into the casing, the casing supplies the air that has flowed into the casing through the electric cable to the sliding surface of the mechanical seal through the through hole.

[0010] During the rotation of the shaft, the mechanical seal sucks the air inside the casing between the sliding surfaces. The mechanical seal can significantly reduce the frictional resistance with a high lubrication function while ensuring a high shaft sealing effect. The mechanical seal is advantageous for energy conservation of underwater equipment.

[0011] The air sucked between the sliding surfaces is discharged outside the mechanical seal, that is, into the water. During the rotation of the shaft, air inside the casing is continuously supplied to the mechanical seal.

[0012] The underwater equipment is equipped with an electric cable. The electric cable may be, for example, a power cable that supplies power to a motor. The electric cable may also be a signal cable. The signal cable is connected to, for example, a sensor of the underwater equipment or a control circuit of the underwater equipment. The electric cable may be both a power cable and a signal cable. The electric cable is a cable necessary for the operation of the underwater equipment.

[0013] In addition to power supply and / or signal transmission and reception, the electric cable has a function of guiding air from the second end in the atmosphere into the casing. The air supply using the electric cable simplifies the structure of the underwater equipment related to the shaft seal of the motor shaft.

[0014] Different from conventional underwater equipment, the underwater equipment disclosed here allows air to flow into the casing that houses the motor. Specifically, the casing supplies the air that has flowed into the casing through the electric cable to the sliding surface of the mechanical seal through the through hole. Since air is stably supplied to the sliding surface of the mechanical seal, the mechanical seal can achieve both high shaft sealing performance and low frictional resistance.

[0015] Also, although air flows into the casing, air is constantly supplied to the mechanical seal during the rotation of the shaft. Different from the conventional sealed casing, a flow of air passing through the inside of the casing occurs. This air flow discharges the moisture in the casing to the outside of the casing. Since the amount of moisture in the casing does not increase, a decrease in the insulation performance of the motor is suppressed.

[0016] The underwater device disclosed herein is a space isolated from the motor, and a dedicated space for supplying air to the mechanical seal is not required. The structure of the casing of the underwater device related to the shaft seal of the motor shaft is also simple.

[0017] Also, the air sucked between the sliding surfaces from inside the casing is discharged outside the mechanical seal, so the pressure inside the casing decreases. Due to the pressure difference between the atmosphere and inside the casing, air is introduced into the casing through the electric cable. The underwater device does not require a structure that forcibly sends air into the casing using power. Also in this regard, the structure of the underwater device related to the shaft seal of the motor shaft is simple.

[0018] The casing includes a second partition wall that rotatably supports the second end portion of the shaft and separates the inside of the casing into a side of the motor and a side opposite to the motor, and a head cover that provides a space between the second partition wall on the side opposite to the motor and covers the second partition wall. The first end of the electric cable may be located in the space between the second partition wall and the head cover.

[0019] The electric cable can introduce air into the space between the second partition wall and the head cover.

[0020] Even in conventional underwater devices, an electric cable may be connected to a motor or a control circuit inside the casing through an insertion hole formed in the head cover. The structure in which the first end of the electric cable is located in the space between the second partition wall and the head cover is basically the same as the arrangement structure of the electric cable in conventional underwater devices. Regarding the arrangement structure of the electric cable, the structure of the underwater device disclosed herein is simple.

[0021] The second partition wall may have a ventilation hole that communicates the side of the motor with the side opposite to the motor.

[0022] The air introduced into the space between the second partition wall and the head cover through the electric cable enters the side of the motor from the ventilation hole, passes through the motor, and reaches the through hole. The air is supplied between the sliding surfaces of the mechanical seal through the through hole. For example, a lead wire connected to the motor may pass through the ventilation hole. Even if the casing has a simple structure, it can stably supply air to the sliding surface of the mechanical seal.

[0023] The underwater device includes a bearing that is held by the partition wall inside the casing and rotatably supports the shaft. The casing may supply the air flowing into the casing through the electric cable to the sliding surface of the mechanical seal through the bearing and the through hole.

[0024] The air flowing into the casing through the electric cable is supplied to the sliding surface of the mechanical seal through the bearing and the through hole. The bearing may be, for example, a rolling bearing. Since the rolling bearing has a gap, a necessary amount of air can be supplied to the sliding surface of the mechanical seal through the rolling bearing. The casing that supplies air to the sliding surface of the mechanical seal through the bearing has a simple structure.

[0025] The electric cable has a conductor and a sheath. The sheath is open at the first end and the second end of the electrical cable. The electrical cable may guide air into the casing through a gap between the conductor and the sheath.

[0026] The electrical cable has a gap between the conductor and the sheath. The gap between the conductor and the sheath can be used to introduce air into the casing. The supply of air using the electrical cable simplifies the structure of the underwater device related to the shaft seal of the motor shaft.

[0027] Another underwater device disclosed herein has an impeller immersed in water, a motor having a shaft with a first end connected to the impeller, a casing for housing the motor, the casing having a partition wall formed with a through hole through which the shaft passes, a mechanical seal interposed between the partition wall and the shaft outside the casing and sealing the shaft by sucking air in the casing between sliding surfaces during rotation of the shaft, a tubular member having a first end opening into the casing, a second end opening into the atmosphere outside the casing, and guiding air flowing in from the second end into the casing, The casing includes a second partition wall that rotatably supports the second end portion of the shaft and separates the inside of the casing into a side of the motor and a side opposite to the motor, and a head cover that provides a space between the second partition wall on the side opposite to the motor and covers the second partition wall. The first end of the tubular member is located in the space between the second partition wall and the head cover. The casing supplies air flowing into the casing through the tubular member to the sliding surfaces of the mechanical seal through the through hole.

[0028] The tubular member guides air from the atmosphere into the casing. The casing supplies the air that has flowed into the casing through the tubular member to the sliding surface of the mechanical seal through the through hole. Since air is stably supplied to the sliding surface of the mechanical seal, the mechanical seal can achieve both high shaft sealing performance and low frictional resistance. Also in this underwater device, the structure related to the shaft seal of the motor shaft is simple.

Effect of the Invention

[0029] The underwater device disclosed herein can simplify the structure related to the shaft seal of the motor shaft.

Brief Description of the Drawings

[0030]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0031] Hereinafter, embodiments of the underwater device will be described with reference to the drawings. The underwater device described here is an example.

[0032] (First Embodiment) FIG. 1 shows an underwater pump 1 according to the first embodiment. The underwater pump 1 is an example of an underwater device. The underwater pump 1 is used while being immersed in water. WL in FIG. 1 indicates the water surface. Note that, for ease of understanding, the position of the water surface WL in FIG. 1 is drawn at a relatively low position.

[0033] The submersible pump 1 includes a pump section 2 and a motor section 3. The submersible pump 1 is a vertical-axis pump. The pump section 2 and the motor section 3 are arranged vertically, and the pump section 2 is located below the motor section 3.

[0034] The pump section 2 includes an impeller 21. The first end 314 of the shaft 313 of the motor 31, which will be described later, is connected to the impeller 21. The first end 314 of the shaft 313 is the lower end of the shaft 313 that extends in the vertical direction in FIG. 1.

[0035] The pump section 2 includes a pump casing 22. The pump casing 22 houses the impeller 21. The pump casing 22 has a suction port 23. The suction port 23 opens downward at the bottom of the pump casing 22. When the impeller 21 rotates, water flows into the pump casing 22 through the suction port 23. The pump casing 22 has a discharge port 24. The discharge port 24 opens upward at the side of the pump casing 22. The discharge port 24 is connected to a pipe (not shown). When the impeller 21 rotates, the water that has flowed into the pump casing 22 is discharged from the discharge port 24.

[0036] The motor section 3 includes a motor 31. The motor 31 is, for example, a three-phase motor. The motor 31 is not limited to a three-phase motor. The motor 31 has a stator 311, a rotor 312, and a shaft 313. The shaft 313 extends in the vertical direction. The lower end of the shaft 313, that is, the first end 314, protrudes downward from the lower end of the rotor 312, and the upper end of the shaft 313, that is, the second end 315, protrudes upward from the upper end of the rotor 312.

[0037] The motor unit 3 includes a motor casing 32. The motor casing 32 houses the motor 31. The motor casing 32 has a main body 321 and a motor cover 322. The main body 321 is substantially cylindrical. The lower end of the main body 321 is closed by a bottom portion 323. The upper end of the main body 321 is open. The motor cover 322 is attached to the upper end of the main body 321. The motor cover 322 closes the opening of the main body 321.

[0038] The bottom portion 323 of the main body 321 is an example of a partition wall that separates the inside and outside of the motor casing 32. The bottom portion 323 has a through hole 324 (see also FIG. 4). The through hole 324 penetrates the bottom portion 323 vertically. The first end portion 314 of the shaft 313 projects downward from the motor casing 32 through the through hole 324.

[0039] The bottom portion 323 holds a first bearing 33. The first bearing 33 is located in the vicinity of the through hole 324 inside the motor casing 32. The first bearing 33 rotatably supports the shaft 313. The first bearing 33 is, for example, a rolling bearing. The first bearing 33 may be a ball bearing.

[0040] The motor cover 322 holds a second bearing 34. The second bearing 34 rotatably supports the second end portion 315 of the shaft 313. The second bearing 34 is, for example, a rolling bearing. The second bearing 34 may be a ball bearing. The motor cover 322 is an example of a second partition wall. The second partition wall separates the inside of the motor unit 3 into the side of the motor 31 and the side opposite to the motor 31.

[0041] The motor unit 3 includes a head cover 35. The motor casing 32 and the head cover 35 are examples of a casing. The head cover 35 is attached to the upper part of the motor casing 32. The space between the head cover 35 and the motor casing 32 is sealed.

[0042] The head cover 35 is substantially cylindrical. The upper end of the head cover 35 is closed. The lower end of the head cover 35 is open. When the head cover 35 is attached to the motor casing 32, an accommodation space 36 is formed between the head cover 35 and the motor casing 32. Electrical components (not shown) are accommodated in the accommodation space 36. The accommodation space 36 formed by the head cover 35 and the motor cover 322 is sealed against water. Also, the internal space of the motor unit 3 formed by the head cover 35 and the motor casing 32 is sealed against water.

[0043] The submersible pump 1 includes a power cable 4. The power cable 4 connects the submersible pump 1 and the control panel 40 to each other. The control panel 40 is located in the atmosphere above the water surface WL. The second end 42 of the power cable 4 is connected to the control panel 40.

[0044] As shown in FIG. 1 or FIG. 2, the first end 41 of the power cable 4 is connected to the submersible pump 1 via a cable boot 5.

[0045] FIG. 2 is an enlarged cross-sectional view of the cable boot 5. The cable boot 5 has a function of introducing the power cable 4 into the motor unit 3 while maintaining the sealed state of the motor unit 3.

[0046] The cable boot 5 is made of rubber and has an insertion portion 51 and a fixing portion 52. The insertion portion 51 is inserted into an insertion hole 351 formed in the head cover 35. The insertion hole 351 penetrates the head cover 35 in the vertical direction. The fixing portion 52 is a flange. The fixing portion 52 is fixed to the upper end surface of the head cover 35 by, for example, bolts.

[0047] Figure 3 is a cross-sectional view of the power cable 4. The power cable 4 has a core wire 43 and a sheath 44. The power cable 4 in the illustrated example is a cable for a three-phase power supply and has three core wires 43. The core wire 43 has a conductor 431 and an insulator 432. The insulator 432 coats the conductor 431. The power cable 4 has a gap 401 between the conductor 431 and the insulator 432. The gap 401 is continuous from the first end 41 to the second end 42 of the power cable 4. The sheath 44 coats the three core wires 43 together. The sheath 44 is the outer skin of the power cable 4. The power cable 4 has a gap 402 between the core wire 43 and the sheath 44. The gap 402 is continuous from the first end 41 to the second end 42 of the power cable 4.

[0048] As shown in Figure 2, the core wire 43 is exposed by peeling off the sheath 44 at the first end 41 of the power cable 4. Inside the cable boot 5, the insulator 432 is partially removed, and solder is poured into the gap of the conductor 431 to prevent moisture from entering through the gap of the conductor 431. A waterproof type heat shrinkable tube 54 is wound around each core wire 43 at the portion where the insulator is removed. The core wire 43 exposed in the accommodation space 36 is electrically connected to the lead wire 53 on the side of the submersible pump 1 in the accommodation space. The cable boot 5 closes the opening of the gap 401 between the conductor 431 and the insulator 432 of the power cable 4 and the opening of the gap 402 between the core wire 43 and the sheath 44. The cable boot 5 not only prevents water from entering the motor unit 3 through the insertion hole 351, but also prevents air from entering the motor unit 3 through the power cable 4. The use of the cable boot 5 is basically the same as that of a conventional submersible pump. Preventing the inflow of air in a conventional submersible pump is because if air enters the motor unit, moisture in the air may accumulate in the motor casing, which may adversely affect the insulation of the motor.

[0049] The water pump 1 is provided with a mechanical seal 6. The mechanical seal 6 seals the shaft 313. The mechanical seal 6 is interposed between the through-hole 324 of the motor casing 32 and the shaft 313 outside the motor casing 32.

[0050] Figure 4 is a cross-sectional view of the mechanical seal 6. The mechanical seal 6 has a mating ring 61 and a seal ring 62. The mating ring 61 is fixed to the bottom 323 of the motor casing 32 so as to surround the through-hole 324. The seal ring 62 is attached to the shaft 313 while being externally inserted into the shaft 313, and is pressed against the mating ring 61 by a compression spring 63. The seal ring 62 rotates integrally with the shaft 313. The sliding surface 611 of the mating ring 61 and the sliding surface 621 of the seal ring 62 face each other in the vertical direction.

[0051] Although not shown in the figure, a dynamic pressure generating groove is formed in the sliding surface 611 of the mating ring 61. When the sliding surface 621 of the seal ring 62 rotates relative to the sliding surface 611 of the mating ring 61 as the shaft 313 rotates, the dynamic pressure generating groove exhibits a function of sucking air in the motor casing 32 between the sliding surfaces 611 and 621 (see the arrow in Figure 4). By the interposition of air between the sliding surfaces 611 and 621, the friction between the sliding surfaces 611 and 621 is reduced, and the intrusion of water between the sliding surfaces 611 and 621 is suppressed. Note that a dynamic pressure generating groove may be formed in the sliding surface 621, or dynamic pressure generating grooves may be formed in both the sliding surface 611 and the sliding surface 621.

[0052] The air supplied between the sliding surfaces 611 and 621 is discharged into the water. During the rotation of the shaft 313, it is necessary to constantly supply the air in the motor casing 32 between the sliding surfaces 611 and 621.

[0053] Here, in the conventional submersible pump, as described above, in order to maintain the insulation of the motor, entry of air into the motor section was suppressed. Also in the submersible pump 1 of FIG. 1, the cable boot 5 suppresses entry of moisture and air into the motor section 3 through the power cable 4.

[0054] The submersible pump 1 of FIG. 1 is different from the conventional submersible pump in that it includes a tubular member 7. The tubular member 7 is a member for supplying air between the sliding surfaces 611 and 621 of the mechanical seal 6. The first end 71 of the tubular member 7 penetrates the head cover 35 in the vertical direction and is located in the accommodation space 36 between the head cover 35 and the motor casing 32. The second end 72 of the tubular member 7 is located in the atmosphere outside the motor casing 32. The first end 71 of the tubular member 7 is the lower end of the tubular member 7, and the second end 72 is the upper end of the tubular member 7. In FIG. 1, the tubular member 7 is a straight circular tube, but the tubular member 7 only needs to have a function of guiding the air flowing into the tube from the second end 72 in the atmosphere to the accommodation space 36. The tubular member 7 is not limited to a straight tube. Also, the tubular member 7 is not limited to a circular tube.

[0055] The motor cover 322 of the motor casing 32 has a ventilation hole 325. The ventilation hole 325 penetrates the motor cover 322 in the vertical direction. The accommodation space 36 and the inside of the motor casing 32 communicate with each other through the ventilation hole 325. The lead wire 53 extending from the motor 31 is drawn into the accommodation space 36 through the ventilation hole 325 and is connected to the core wire 43. In FIG. 1, for ease of understanding, only one lead wire 53 is connected to the core wire 43. As will be described later, the ventilation hole 325 not only allows air to pass from the accommodation space 36 to the inside of the motor casing 32, but also functions as a passage hole for the lead wire 53. Note that the passage hole for the lead wire 53 may be formed in the motor cover 322 separately from the ventilation hole 325. Also, in FIG. 1, the ventilation hole 325 is drawn relatively large. The size of the ventilation hole 325 can be an appropriate size. The ventilation hole 325 is not limited to being formed in the motor cover 322.

[0056] The air that flows into the accommodation space 36 through the tubular member 7 enters the motor casing 32 through the ventilation holes 325 as indicated by the arrows in FIG. 1 or FIG. 4, and passes through the gap between, for example, the stator 311 and the rotor 312 of the motor 31 in the vertical direction. The air that has passed through the motor 31 reaches between the sliding surfaces 611 and 621 of the mechanical seal 6 through the first bearing 33 and the through hole 324. Here, since the first bearing 33 is a rolling bearing, it has a gap. The air flowing along the shaft 313 can pass through the first bearing 33. During the rotation of the shaft 313, air is stably supplied between the sliding surfaces 611 and 621 of the mechanical seal 6. The mechanical seal 6 can achieve both high shaft sealing performance and low frictional resistance.

[0057] Since the dynamic pressure generating grooves suck air from inside the motor casing 32 between the sliding surfaces 611 and 621, the pressure inside the motor casing 32 decreases. Due to the pressure difference between the atmosphere and inside the motor casing 32, air is automatically supplied into the motor casing 32 through the tubular member 7. For example, there is no need to forcibly send air into the motor casing 32 using power.

[0058] In the submersible pump 1, air flows into the motor casing 32. However, unlike the conventional sealed motor casing, air is constantly supplied to the mechanical seal 6 during the rotation of the shaft 313. A flow of air passing through the inside of the motor casing 32 is generated. Due to this air flow, the moisture inside the motor casing 32 is discharged outside the motor casing 32. Since the amount of moisture inside the motor casing 32 does not increase, a decrease in the insulation performance of the motor 31 is suppressed.

[0059] The submersible pump 1 can supply air between the sliding surfaces 611 and 621 of the mechanical seal 6 simply by substantially adding the tubular member 7. A dedicated space for supplying air to the mechanical seal 6 is not required in the motor casing 32. The structure of the submersible pump 1 related to the shaft seal of the shaft 313 of the motor 31 is simple.

[0060] (Second Embodiment) FIG. 5 shows a submersible pump 10 according to the second embodiment. The submersible pump 10 supplies air between the sliding surfaces 611 and 621 of the mechanical seal 6 without using the tubular member 7. The submersible pump 10 supplies air between the sliding surfaces 611 and 621 of the mechanical seal 6 using the power cable 4.

[0061] As shown in FIG. 3, the power cable 4 has a gap 402 between the core wire 43 and the sheath 44. The power cable 4 also has a gap 401 between the conductor 431 and the insulator 432. The insulator 432 is an example of a sheath.

[0062] The submersible pump 10 does not include the cable boot 5. The first end 41 of the power cable 4 is located in the accommodation space 36 through the insertion hole 351 of the head cover 35. Here, the head cover 35 has a recess 352 around the insertion hole 351. The recess 352 is filled with a packing 353. The packing 353 seals the motor unit 3 by closing the gap between the sheath 44 of the power cable 4 and the insertion hole 351. Note that reference numeral 354 is a packing retainer 354 that presses the packing 353. The connection structure of the power cable 4 using the packing 353 is simpler than the conventional connection structure of the power cable 4 using the cable boot 5. The core wire 43 of the power cable 4 is connected to the lead wire 53 drawn into the accommodation space 36 through the ventilation hole 325 in the accommodation space 36.

[0063] The first end 41 of the power cable 4 is open in the accommodation space 36. The second end 42 of the power cable 4 connected to the control panel 40 is open in the atmosphere. The air flowing into the power cable 4 from the second end 42 reaches the inside of the accommodation space 36 from the first end 41 through the gaps 401 and 402 of the power cable 4 (see the arrow in FIG. 5).

[0064] The air flowing into the accommodation space 36 through the power cable 4 enters the motor casing 32 through the ventilation holes 325 as indicated by the arrows in Fig. 5, passes through the motor 31 in the vertical direction, and reaches between the sliding surfaces 611 and 621 of the mechanical seal 6 through the first bearing 33 and the through hole 324. During the rotation of the shaft 313, air is stably supplied between the sliding surfaces 611 and 621 of the mechanical seal 6. The mechanical seal 6 can achieve both high shaft sealing performance and low frictional resistance.

[0065] The submersible pump 10 does not include the tubular member 7 and the cable boot 5. The air supply structure using the power cable 4 simplifies the structure of the submersible pump 10 related to the shaft seal of the shaft 313. The power cable 4 can be regarded as an example of a tubular member that guides air into the pump section 3.

[0066] Note that the electrical cable that can be used for air supply to the mechanical seal 6 is not limited to the power cable 4. For example, air may be supplied to the submersible pump 10 using a signal cable. The signal cable is, for example, a cable connected to a sensor of the submersible pump or a control circuit of the submersible pump. Also, air may be supplied to the mechanical seal 6 using both the power cable 4 and the signal cable.

[0067] The submersible pump to which the technology disclosed herein is applicable is not limited to the submersible pumps 1 and 10 having the structures illustrated in Fig. 1 or Fig. 5. The technology disclosed herein can be applied, for example, to a submersible pump with a horizontal shaft.

[0068] Also, the technology disclosed herein is not limited to application to submersible pumps. The technology disclosed herein can be widely applied to underwater devices having a mechanical seal that sucks air in the casing, such as an underwater mixer, an agitator, and an aerator.

Description of Reference Numerals

[0069] 1 Submersible pump (underwater device) 10 Submersible pump (underwater device) 21 Blades 31 Motor 313 Shaft 314 First End 315 Second End 32 Motor Casing (Casing) 322 Motor Cover (Second Partition) 323 Bottom (Partition) 324 Through-Hole 325 Vent Hole 33 First Bearing 35 Head Cover (Casing) 36 Accommodation Space (Space) 4 Power Cable (Electrical Cable) 401 Gap 402 Gap 41 First End (of Power Cable) 42 Second End (of Power Cable) 43 Core Wire 431 Conductor 432 Insulator (Sheath) 44 Sheath 6 Mechanical Seal 611 Sliding Surface 621 Sliding Surface 7 Tubular Member 71 First End (of Tubular Member) 72 Second End (of Tubular Member)

Claims

1. An impeller immersed in water, a motor having a shaft with a first end connected to the impeller, a casing for housing the motor, the casing having a partition wall formed with a through-hole through which the shaft passes, a mechanical seal interposed between the partition wall and the shaft outside the casing and sealing the shaft by sucking air in the casing between sliding surfaces during rotation of the shaft, an electric cable having a first end located inside the casing and a second end located in the atmosphere outside the casing, the electric cable guiding air flowing into the electric cable from the second end into the casing, the casing being an underwater device that supplies air flowing into the casing through the electric cable to the sliding surface of the mechanical seal through the through-hole.

2. The underwater device according to claim 1, wherein the casing includes a second partition wall that rotatably supports a second end portion of the shaft and separates the inside of the casing into a side of the motor and a side opposite to the motor, and a head cover that provides a space between the second partition wall on the side opposite to the motor and covers the second partition wall, wherein the first end of the electric cable is located in the space between the second partition wall and the head cover.

3. The underwater device according to claim 2, wherein the second partition wall has a vent hole that communicates the side of the motor and the side opposite to the motor.

4. The underwater device according to claim 1, comprising a bearing held by the partition wall inside the casing and rotatably supporting the shaft, wherein the casing supplies air flowing into the casing through the electric cable to the sliding surface of the mechanical seal through the bearing and the through-hole.

5. The underwater device according to any one of claims 1 to 4, wherein the electric cable has a conductor and a sheath, the sheath being open at the first end and the second end of the electric cable, the electric cable guiding air into the casing through a gap between the conductor and the sheath.

6. An impeller immersed in water, a motor having a shaft with a first end connected to the impeller, A casing that houses the motor, the casing having a partition wall formed with a through-hole through which the shaft passes; A mechanical seal that is interposed between the partition wall and the shaft outside the casing and that seals the shaft by sucking air in the casing between sliding surfaces during rotation of the shaft; A tubular member having a first end opening into the casing, a second end opening into the atmosphere outside the casing, and guiding air flowing in from the second end into the casing; and The casing includes a second partition wall that rotatably supports a second end portion of the shaft and separates the inside of the casing into a side of the motor and a side opposite to the motor, and a head cover that provides a space between the second partition wall on the side opposite to the motor and covers the second partition wall; The first end of the tubular member is located in the space between the second partition wall and the head cover; The casing is an underwater device that supplies air flowing into the casing through the tubular member to the sliding surface of the mechanical seal through the through-hole.

Images