JP2017227131A - Pump device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pump device capable of removing foreign substances blocked in a clearance between a slide bearing and a rotary shaft.SOLUTION: A pump device is equipped with a canned motor pump which is equipped with an impeller 1 for transporting liquid, a rotary shaft 2 to which the impeller 1 is fixed, a pump casing 4 storing the impeller 1, slide bearings 21 and 22 which rotatably support the rotary shaft 2, and a motor 10 rotating the rotary shaft 2; and an inverter device 40 which supplies a current to the motor 10. The canned motor pump has a structure which leads a part of liquid sucked into the pump casing 4 into a space 23 in which the slide bearings 21 and 22 are disposed, and lubricates the slide bearings 21 and 22 with the liquid led into the space 23. The inverter device 40 makes the motor 10 to perform inverse rotating action for rotating the impeller 1 in an inverting direction, when the current exceeds a threshold value during normal rotations of the impeller 1.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a pump device for transferring a liquid.

  There are flammable and toxic liquids in the pump equipment used in the oil refining, petrochemical, and chemical industries, and it is very dangerous if such liquid leaks to the outside. The pump device is a rotating machine that pumps liquid by rotating an impeller disposed in a pump casing. A pump device having a motor outside the pump includes a shaft seal device such as a mechanical seal or a gland packing in order to seal a gap between the rotary shaft and the pump casing. However, when the pump device is operated for a long period of time, the shaft seal device deteriorates, and as a result, dangerous liquid may leak to the outside from the gap between the rotating shaft and the pump casing.

  Since the canned motor pump in which the motor and the pump are integrally configured does not require the shaft seal device as described above, liquid leakage does not occur. Accordingly, the canned motor pump is widely used in the field of handling dangerous liquids.

JP 2001-153085 A JP-A-2015-59480 JP-A-2015-218586

  The canned motor pump has a structure in which a liquid circulates inside the canned motor pump, and the circulated liquid functions as a lubricant for a slide bearing that supports the rotating shaft. Therefore, if foreign matter is mixed in the circulating liquid, the foreign matter may be clogged in the gap inside the canned motor pump.

  Foreign objects can be mixed into the liquid for various reasons. Therefore, it is a common practice to provide a filter for removing foreign substances from the liquid. However, when a very fine filter (for example, the opening is several μm) is used, a pressure loss of the liquid is generated in the filter, and the canned motor pump cannot satisfactorily exhibit its performance. For these reasons, a filter with a relatively coarse mesh (for example, an opening of about 100 μm) is usually used.

  Since most of the gaps inside the canned motor pump are larger than 100 μm, foreign matters are not clogged in such gaps. However, since the size of the gap between the slide bearing and the rotary shaft is several μm to several tens of μm, there is a possibility that foreign matter that has passed through the filter is clogged in the gap between the slide bearing and the rotary shaft. In order to prevent such clogging of foreign matters, if the size of the gap between the slide bearing and the rotating shaft is made larger than 100 μm, the dynamic pressure necessary for supporting the rotating shaft is not generated, and the bearing Since the function is impaired, it is difficult to increase the gap.

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide a pump device that can remove foreign substances clogged in a gap between a slide bearing and a rotary shaft.

  In order to achieve the above-described object, according to one aspect of the present invention, an impeller for transferring a liquid, a rotating shaft to which the impeller is fixed, a pump casing that houses the impeller, and the rotating shaft A canned motor pump including a plain bearing that rotatably supports the motor, a motor that rotates the rotating shaft, and an inverter device that supplies current to the motor. The canned motor pump is sucked into the pump casing. A part of the liquid is guided to a space where the slide bearing is disposed, and the slide bearing is lubricated by the liquid guided to the space. When the current exceeds a threshold value during rotation, the motor performs a reverse rotation operation for rotating the impeller in the reverse direction. It is a device.

In a preferred aspect of the present invention, the rotation of the impeller in the reverse direction is within one rotation.
In a preferred aspect of the present invention, a filter is provided at the suction port of the pump casing.
In a preferred aspect of the present invention, the size of each opening of the filter is larger than the gap between the sliding bearing and the rotating shaft and smaller than the gap between the impeller and the pump casing. It is characterized by.

In a preferred aspect of the present invention, the inverter device stops the rotation of the impeller when the current exceeds the threshold value, and then causes the motor to perform the reverse rotation operation. And
In a preferred aspect of the present invention, after the reverse rotation operation is performed and the current exceeds the threshold value when the impeller is rotating in the forward direction, the inverter device is The reverse rotation operation is performed again by the motor.
In a preferred aspect of the present invention, after the reverse rotation operation is performed a predetermined number of times, and when the current exceeds the threshold value when the impeller is rotating in the forward direction, The inverter device generates an alarm.

  Another aspect of the present invention is an impeller for transferring a liquid, a rotary shaft to which the impeller is fixed, a pump casing that houses the impeller, and a slide bearing that rotatably supports the rotary shaft. And a canned motor pump comprising a motor that rotates the rotating shaft, and an inverter device that supplies current to the motor, wherein the canned motor pump is configured to remove a portion of the liquid sucked into the pump casing. The sliding bearing is guided to the space where the sliding bearing is disposed, and the sliding bearing is lubricated by the liquid guided to the space, and the inverter device calculates the rate of change of the current per predetermined period, When the rate of change of current is greater than a predetermined set value, the pump device is characterized in that the motor performs a reverse rotation operation for rotating the impeller in the reverse direction. That.

In a preferred aspect of the present invention, the rotation of the impeller in the reverse direction is within one rotation.
In a preferred aspect of the present invention, a filter is provided at the suction port of the pump casing.
In a preferred aspect of the present invention, the size of each opening of the filter is larger than the gap between the sliding bearing and the rotating shaft and smaller than the gap between the impeller and the pump casing. It is characterized by.

In a preferred aspect of the present invention, the inverter device newly calculates a change rate of the current per predetermined period after the reverse rotation operation is performed, and the newly calculated change rate of the current is When it is larger than a set value, the reverse rotation operation is caused to be performed again by the motor.
In a preferred aspect of the present invention, the inverter device updates the current change rate by calculating the current change rate per predetermined period after the reverse rotation operation is performed a predetermined number of times. When the change rate of the current that is generated is greater than the set value, the inverter device issues an alarm.

  When the foreign matter is clogged in the gap between the slide bearing and the rotary shaft, the current supplied to the motor increases. According to the present invention, when the current exceeds the threshold value or when the rate of change of the current exceeds the set value, the impeller rotates in the reverse direction. The rotating shaft that rotates in reverse with the impeller can remove foreign substances clogged in the gap between the slide bearing and the rotating shaft.

It is a figure which shows one Embodiment of a pump apparatus. It is a figure which shows the flow of the liquid in a pump apparatus. It is a flowchart which shows one Embodiment of the order of the process for removing the foreign material performed when the electric current to a motor rises. It is a flowchart which shows one Embodiment of the order of the process for removing the foreign material performed when the rate of change of an electric current rises.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram showing an embodiment of a pump device. In the present embodiment, the pump device includes a canned motor pump. The canned motor pump has a structure in which a liquid circulates inside. As shown in FIG. 1, the canned motor pump includes a pump P and a motor unit M for driving the pump P. The pump P includes an impeller 1 for transferring liquid, a rotating shaft 2 to which the impeller 1 is fixed, a liner ring 3 disposed so as to surround a liquid inlet of the impeller 1, the impeller 1 and the liner. And a pump casing 4 for housing the ring 3.

  A casing cover 5 is fixed to the opening on the high pressure side of the pump casing 4. The rotating shaft 2 extends through the casing cover 5, and the impeller 1 is fixed to the tip of the rotating shaft 2 by a fastener 6. In the casing cover 5, a flow hole 5 a for guiding a part of the liquid sucked into the pump casing 4 to the motor portion M, more specifically, to the gap between the slide bearings 21, 22 and the rotary shaft 2. Is formed. A part of the liquid pressurized by the rotation of the impeller 1 is guided to the motor part M through the flow hole 5a.

  The pump device includes a motor 10 that rotates the rotary shaft 2, slide bearings 21 and 22 that rotatably support the rotary shaft 2, and a motor frame 12 that houses the rotary shaft 2, the motor 10, and the slide bearings 21 and 22. It has. The motor 10 includes a motor rotor 15 fixed to the rotary shaft 2 and a motor stator 16 disposed around the motor rotor 15. In the present embodiment, the motor rotor 15 is fixed to the central portion of the rotating shaft 2. The motor stator 16 includes a stator core 16a and a plurality of coils 16b wound around the stator core 16a. Although only one coil 16 b is shown in FIG. 1, the plurality of coils 16 b are arranged so as to surround the motor rotor 15.

  The rotating shaft 2 is rotatably supported by slide bearings 21 and 22 disposed on both sides of the motor rotor 15. The slide bearing 21 includes a radial bearing 21a that supports the radial load of the rotating shaft 2, a thrust bearing 21b that supports the thrust load of the rotating shaft 2 (more specifically, a thrust plate 25 fixed to the rotating shaft 2), and It is composed of Similarly, the slide bearing 22 includes a radial bearing 22a and a thrust bearing 22b. The thrust plates 25, 25 have an annular shape and are fixed to the rotary shaft 2 at positions on both sides of the motor rotor 15. The thrust plates 25, 25 rotate integrally with the rotary shaft 2.

  A cylindrical can 18 is disposed between the motor rotor 15 and the motor stator 16 so as to surround the motor rotor 15. The motor stator 16 is disposed between the motor frame 12 and the can 18. The motor stator 16 is in contact with the inner surface of the motor frame 12 and the outer surface of the can 18. The motor rotor 15, the motor stator 16, and the can 18 are arranged concentrically. An annular frame side plate 13 is provided adjacent to the motor stator 16. The outer surface of the frame side plate 13 is fixed to the motor frame 12, and the inner surface of the frame side plate 13 is fixed to the can 18. The motor stator 16 is disposed in the stator chamber 11 formed by the motor frame 12, the frame side plate 13, and the can 18.

  The casing cover 5 is disposed between the frame side plate 13 and the pump casing 4. Between the casing cover 5 and the pump casing 4 and between the casing cover 5 and the frame side plate 13, annular seal members 17 and 17 are arranged, respectively. These seal members 17 and 17 prevent liquid from flowing out of the pump device through these gaps. An end cover 19 is disposed on the opposite side of the casing cover 5, and the opening on the end side of the motor frame 12 is closed by the end cover 19.

  The cylindrical radial bearing 21a is disposed between the rotating shaft 2 and the casing cover 5, and a slight gap is formed between the outer peripheral surface of the rotating shaft 2 and the inner peripheral surface of the radial bearing 21a. . Similarly, the cylindrical radial bearing 22a is disposed between the rotary shaft 2 and the end cover 19, and a slight gap is formed between the outer peripheral surface of the rotary shaft 2 and the inner peripheral surface of the radial bearing 22a. Has been.

  The annular thrust bearing 21 b is disposed between the thrust plate 25 and the casing cover 5. The annular thrust bearing 22 b is disposed between the thrust plate 25 and the end cover 19.

  When a current is passed through the coil 16b of the motor stator 16, a magnetic field is formed in the motor stator 16, and the motor rotor 15 is rotated by this magnetic field. The rotation of the motor rotor 15 rotates the impeller 1 through the rotating shaft 2. When the impeller 1 rotates together with the rotating shaft 2, the liquid is sucked into the pump casing 4 from the suction port 4a, and after the pressure is increased by the rotation of the impeller 1, the liquid is discharged from the discharge port 4b.

  FIG. 2 is a diagram showing the flow of liquid in the pump device. As shown by the arrow in FIG. 2, a part of the liquid sucked into the pump casing 4 is guided to the motor unit M, that is, the space 23 in which the slide bearings 21 and 22 are arranged through the flow hole 5a. The liquid flows through the gap between the thrust bearing 21b and the casing cover 5 and the gap between the thrust bearing 21b and the thrust plate 25, and further rotates with the slide bearing 21 (that is, the radial bearing 21a and the thrust bearing 21b). It flows through the gap between the shaft 2. In this way, the liquid cools and lubricates the rotating shaft 2 and the slide bearing 21, and further cools the motor 10.

  The impeller 1 is formed with a through hole 1a extending in the axial direction thereof. The liquid supplied to the gap between the slide bearing 21 and the rotary shaft 2 is returned into the impeller 1 through the through hole 1 a of the impeller 1. Since the stator chamber 11 is sealed, the liquid does not contact the motor stator 16 in the stator chamber 11.

  A part of the liquid guided to the motor unit M is guided to the space 23 in which the slide bearing 22 is disposed through a slight gap between the motor rotor 15 and the can 18. The liquid flows through the gap between the thrust bearing 22b and the end cover 19 and the gap between the thrust bearing 22b and the thrust plate 25, and further rotates with the slide bearing 22 (that is, the radial bearing 22a and the thrust bearing 22b). It flows through the gap between the shaft 2. In this way, the liquid cools and lubricates the rotating shaft 2 and the sliding bearing 22.

  A shaft through hole 2 a penetrating in the axial direction is formed inside the rotary shaft 2, and the shaft through hole 2 a is open at both ends of the rotary shaft 2. The liquid that has flowed through a slight gap between the slide bearing 22 and the rotary shaft 2 is returned into the pump casing 4 through the shaft through hole 2a.

  As described above, the canned motor pump according to the present embodiment guides a part of the liquid sucked into the pump casing 4 to the space 23 in which the slide bearings 21 and 22 are disposed, and the liquid guided to the space 23 causes the slip. The bearings 21 and 22 are lubricated (and cooled).

  As shown in FIGS. 1 and 2, a filter 27 is provided in the suction port 4 a of the pump casing 4. A large number of openings are formed in the filter 27, and the filter 27 is configured to capture foreign substances in the liquid. The size of the opening of the filter 27 is larger than the gap between the slide bearings 21 and 22 and the rotary shaft 2 and smaller than the gap between the impeller 1 and the pump casing 4. The reason is as follows. The clearance between the slide bearings 21 and 22 and the rotating shaft 2 is very small, and is usually several μm to several tens of μm. If the opening of the filter 27 is smaller than the gap between the slide bearings 21 and 22 and the rotary shaft 2, a pressure loss of the liquid occurs in the filter 27, and the pump device cannot exhibit its performance satisfactorily. On the other hand, if the opening of the filter 27 is larger than the gap between the impeller 1 and the pump casing 4, foreign matter that has passed through the filter 27 may be clogged in the gap between the impeller 1 and the pump casing 4. .

  Since each opening of the filter 27 is larger than the gap between the slide bearings 21 and 22 and the rotary shaft 2, foreign matter that has passed through the filter 27 may be clogged into the gap between the slide bearings 21 and 22 and the rotary shaft 2. There is. Furthermore, foreign matter may be clogged in the gap between the thrust bearing 21 b and the thrust plate 25 and / or the gap between the thrust bearing 21 b and the casing cover 5. Similarly, foreign matter may be clogged in the gap between the thrust bearing 22 b and the thrust plate 25 and / or the gap between the thrust bearing 22 b and the end cover 19. The pump device according to the present embodiment is configured to be able to remove foreign substances clogged in these gaps.

  As shown in FIG. 1, the pump device further includes an inverter device 40 that supplies current to the motor 10. The inverter device 40 supplies current to the motor 10 to rotate the motor 10 at a preset speed. The torque of the motor 10 depends on the magnitude of the current supplied to the motor 10. As long as the load applied to the motor 10 is constant, the current supplied to the motor 10 is generally constant while the motor 10 and the impeller 1 are rotating at a predetermined speed.

  If the current exceeds the threshold value when the impeller 1 is rotating in the forward direction, the inverter device 40 causes the motor 10 to perform a reverse rotation operation that rotates the impeller 1 in the reverse direction. That is, the inverter device 40 reverses the rotation direction of the motor 10, whereby the motor 10 rotates the impeller 1 in the reverse direction. In this specification, the rotation direction of the impeller 1 when the liquid is transferred from the suction port 4a to the discharge port 4b is defined as the forward direction, and the rotation direction opposite to the forward direction is defined as the reverse direction.

  When foreign matter in the liquid is clogged in the gap between the rotary shaft 2 and the slide bearing 21 or the slide bearing 22, the load applied to the motor 10 increases, and the current supplied from the inverter device 40 to the motor 10 increases. When the current supplied to the motor 10 exceeds a predetermined threshold value, the inverter device 40 is configured to stop the supply of current to the motor 10 and stop the rotation of the impeller 1.

  Further, the inverter device 40 causes the motor 10 to perform the reverse rotation operation after stopping the rotation of the impeller 1. By this reverse rotation operation, a force in the direction opposite to that when the impeller 1 rotates in the forward direction acts on the foreign matter, and the foreign matter is released from the gap between the rotary shaft 2 and the slide bearing 21 or the slide bearing 22. As a result, foreign matter is removed.

  According to this embodiment, it is possible to remove foreign substances clogged in the gap between the rotary shaft 2 and the slide bearing 21 and / or the slide bearing 22. Further, the gap between the thrust bearing 21b and the thrust plate 25 and / or the gap between the thrust bearing 21b and the casing cover 5, the gap between the thrust bearing 22b and the thrust plate 25, and / or the thrust bearing 22b and the end. Foreign matter clogged in the gap between the cover 19 and the cover 19 can be removed.

  FIG. 3 is a flow chart illustrating one embodiment of the sequence of steps for removing foreign matter performed when the current to the motor 10 increases. As described above, when foreign matter in the liquid is clogged in the gap between the rotary shaft 2 and the slide bearing 21 or the slide bearing 22, and the current supplied to the motor 10 exceeds a predetermined threshold (step 1), The inverter device 40 stops the supply of current to the motor 10 and stops the rotation of the impeller 1 (step 2). Thereafter, the inverter device 40 causes the motor 10 to perform the reverse rotation operation, and rotates the rotary shaft 2 and the impeller 1 in the reverse direction (step 3). In order to prevent the sliding bearings 21 and 22 from being damaged, it is preferable that the rotation of the impeller 1 in the reverse direction is within one rotation.

  The inverter device 40 causes the motor 10 to perform the reverse rotation operation, then stops the supply of current to the motor 10 and stops the rotation of the impeller 1 (step 4). Thereafter, the inverter device 40 reverses the rotation direction of the motor 10 and rotates the impeller 1 in the forward direction (step 5). Thereafter, the inverter device 40 determines whether or not the current supplied to the motor 10 exceeds the threshold value when the impeller 1 is rotating in the forward direction (step 6). If the current does not exceed the threshold value, the inverter device 40 continues to rotate the impeller 1 in the positive direction (step 7).

  If the current supplied to the motor 10 exceeds the threshold value after the reverse rotation operation described above is performed and the impeller 1 is rotating in the forward direction, the inverter device 40 The motor 10 is caused to rotate again. As shown in step 8 of FIG. 3, the reverse rotation operation is performed a predetermined number of times. The inverter device 40 determines whether or not the number of reverse rotation operations is within a predetermined number. If the number of reverse rotation operations is within a predetermined number, the inverter device 40 stops the rotation of the impeller 1 and The motor 10 is caused to perform the reverse rotation operation again. The number of reverse rotation operations is arbitrarily determined. For example, the number of reverse rotation operations is five. The inverter device 40 is configured to count the number of reverse rotation operations and store the counted number.

  After the reverse rotation operation is performed again, the inverter device 40 stops the supply of current to the motor 10 and stops the rotation of the impeller 1. Thereafter, the inverter device 40 rotates the motor 10 in the forward direction and rotates the impeller 1 in the forward direction again. When the current supplied to the motor 10 does not exceed the threshold value, the inverter device 40 continues to rotate the impeller 1 in the positive direction.

  When the reverse rotation operation is performed a predetermined number of times and the current supplied to the motor 10 exceeds the threshold value when the impeller 1 is rotating in the forward direction, the inverter device 40 is The supply of current to the motor 10 may be stopped, the rotation of the impeller 1 may be stopped (step 9), and an alarm may be issued (step 10). In one embodiment, the inverter device 40 includes a display unit, and the inverter device 40 displays error information indicating that the operation of the pump device cannot be resumed on the display unit.

  The inverter device 40 may prevent the motor 10 from performing reverse rotation before the rotation of the impeller 1 is stopped in order to prevent the impeller 1 from stopping. Hereinafter, other embodiments of the reverse rotation operation will be described.

  When the foreign matter is clogged in the clearance between the slide bearing 21 or the slide bearing 22 and the rotary shaft 2, the load applied to the motor 10 increases, and the current supplied from the inverter device 40 to the motor 10 increases. The inverter device 40 is configured to monitor the current supplied to the motor 10 and calculate the rate of change of current per predetermined period (for example, one month). In one embodiment, the inverter device 40 calculates the rate of change of current per predetermined period (for example, one month).

  As long as the load on the motor 10 does not change, the current supplied from the inverter device 40 to the motor 10 is constant, and therefore the rate of change of current per predetermined period is substantially zero. The inverter device 40 causes the motor 10 to perform a reverse rotation operation when the rate of change of current per predetermined period is greater than a predetermined set value. The predetermined set value is arbitrarily determined. In one embodiment, the predetermined set value is 10%.

  FIG. 4 is a flowchart showing an embodiment of a sequence of steps for removing foreign matter that is executed when the rate of change in current increases. As shown in step 1 of FIG. 4, the inverter device 40 calculates the rate of change of current per predetermined period (step 1) and compares the calculated rate of change of current with a predetermined set value (step 1). 2). If the calculated rate of change of current is greater than the set value, the inverter device 40 stops supplying current to the motor 10 and stops the rotation of the impeller 1 (step 3). Thereafter, the inverter device 40 causes the motor 10 to perform a reverse rotation operation (step 4), and rotates the rotary shaft 2 and the impeller 1 in the reverse direction. Also in this embodiment, the rotation of the impeller 1 in the reverse direction is preferably within one rotation.

  After the reverse rotation operation is performed, the inverter device 40 stops the supply of current to the motor 10 and stops the rotation of the impeller 1 (step 5). Thereafter, the inverter device 40 reverses the rotation direction of the motor 10 and rotates the impeller 1 in the forward direction (step 6). Thereafter, the inverter device 40 newly calculates a current change rate per predetermined period (step 7), and compares the newly calculated current change rate with the set value (step 8). When the newly calculated current change rate is smaller than the set value, the inverter device 40 continues to rotate the impeller 1 in the positive direction.

  When the newly calculated current change rate is larger than the set value, the inverter device 40 causes the motor 10 to perform the reverse rotation operation again. As shown in step 9 of FIG. 4, the reverse rotation operation is performed a predetermined number of times. The inverter device 40 determines whether or not the number of reverse rotation operations is within a predetermined number. If the number of reverse rotation operations is within a predetermined number, the inverter device 40 stops the rotation of the impeller 1 and The motor 10 is caused to perform the reverse rotation operation again.

  After the reverse rotation operation is performed, the inverter device 40 stops the rotation of the impeller 1 and rotates the impeller 1 in the forward direction. Thereafter, the inverter device 40 calculates the rate of change of current per predetermined period, updates the rate of change of current, and compares the updated rate of change of current with the set value. When the updated rate of change in current is smaller than the set value, the inverter device 40 continues to rotate the impeller 1 in the positive direction.

  When the reverse rotation operation is performed a predetermined number of times, the inverter device 40 recalculates the current change rate per predetermined period to update the current change rate, and the updated current change rate and the above setting Compare the value. If the updated current change rate is larger than the set value, the inverter device 40 may stop the rotation of the impeller 1 (step 10) and issue an alarm (step 11). In one embodiment, the inverter device 40 includes a display unit, and the inverter device 40 displays information indicating that maintenance of the pump device is necessary on the display unit.

  You may combine the element of embodiment shown in FIG. 3, and the element of embodiment shown in FIG. That is, the inverter device 40 can cause the motor 10 to perform a reverse rotation operation when the current supplied to the motor 10 exceeds a predetermined threshold value when the impeller 1 is rotating in the forward direction. Further, when the rate of change of current per predetermined period is larger than a predetermined set value, the motor 10 can be caused to perform a reverse rotation operation.

  The embodiment described above is described for the purpose of enabling the person having ordinary knowledge in the technical field to which the present invention belongs to implement the present invention. Various modifications of the above embodiment can be naturally made by those skilled in the art, and the technical idea of the present invention can be applied to other embodiments. Accordingly, the present invention is not limited to the described embodiments, but is to be construed in the widest scope according to the technical idea defined by the claims.

DESCRIPTION OF SYMBOLS 1 Impeller 1a Through-hole 2 Rotating shaft 2a Shaft through-hole 3 Liner ring 4 Pump casing 4a Suction port 4b Discharge port 5 Casing cover 5a Flowing hole 6 Fastener 10 Motor 11 Stator chamber 12 Motor frame 13 Frame side plate 15 Motor rotor 16 Motor stator 16a Stator core 16b Coil 17 Seal member 18 Can 21, 22 Slide bearing 21a, 22a Radial bearing 21b, 22b Thrust bearing 23 Space 25 Thrust plate 27 Filter 40 Inverter device

Claims (13)

An impeller for transferring liquid, a rotating shaft to which the impeller is fixed, a pump casing that houses the impeller, a slide bearing that rotatably supports the rotating shaft, and the rotating shaft. A canned motor pump comprising a motor;
An inverter device for supplying current to the motor,
The canned motor pump has a structure in which a part of the liquid sucked into the pump casing is guided to a space where the sliding bearing is disposed, and the sliding bearing is lubricated by the liquid guided to the space. ,
The inverter device causes the motor to perform a reverse rotation operation to rotate the impeller in the reverse direction when the current exceeds a threshold value when the impeller is rotating in the forward direction. A pump device characterized.   The pump device according to claim 1, wherein the rotation of the impeller in the reverse direction is within one rotation.   The pump device according to claim 1 or 2, wherein a filter is provided at a suction port of the pump casing.   The size of each opening of the filter is larger than a gap between the sliding bearing and the rotating shaft, and smaller than a gap between the impeller and the pump casing. The pump device described in 1.   The said inverter apparatus stops the rotation of the said impeller when the said electric current exceeds the said threshold value, and makes the said motor perform the said reverse rotation operation | movement after that. The pump device according to any one of the above.   After the reverse rotation operation is performed, and when the current exceeds the threshold value when the impeller is rotating in the forward direction, the inverter device performs the reverse rotation operation as described above. The pump device according to any one of claims 1 to 5, wherein the motor is re-executed.   After the reverse rotation operation has been performed a predetermined number of times, if the current exceeds the threshold value when the impeller is rotating in the forward direction, the inverter device issues an alarm The pump device according to claim 6. An impeller for transferring liquid, a rotating shaft to which the impeller is fixed, a pump casing that houses the impeller, a slide bearing that rotatably supports the rotating shaft, and the rotating shaft. A canned motor pump comprising a motor;
An inverter device for supplying current to the motor,
The canned motor pump has a structure in which a part of the liquid sucked into the pump casing is guided to a space where the sliding bearing is disposed, and the sliding bearing is lubricated by the liquid guided to the space. ,
The inverter device calculates a rate of change of the current per predetermined period, and when the rate of change of the current is larger than a predetermined set value, the inverter device performs a reverse rotation operation for rotating the impeller in the reverse direction. A pump device characterized by being made to perform.   The pump device according to claim 8, wherein the impeller rotates in the reverse direction within one rotation.   The pump device according to claim 8 or 9, wherein a filter is provided at a suction port of the pump casing.   The size of each opening of the filter is larger than a gap between the sliding bearing and the rotary shaft, and smaller than a gap between the impeller and the pump casing. The pump device described in 1. The inverter device is
After the reverse rotation operation is performed, the rate of change of the current per predetermined period is newly calculated,
The pump according to any one of claims 8 to 11, wherein when the newly calculated rate of change of the current is larger than the set value, the reverse rotation operation is performed again by the motor. apparatus. The inverter device is
After the reverse rotation operation is performed a predetermined number of times, the rate of change of the current per predetermined period is calculated to update the rate of change of the current,
The pump device according to claim 12, wherein the inverter device issues an alarm when the updated rate of change of the current is larger than the set value.

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