JP2011058447A - Vertical shaft pump and method for monitoring submerged bearing used for vertical shaft pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vertical shaft pump including a mechanism executing reliable wear detection of a submerged bearing and accurately monitoring wear of the submerged bearing without disassembling a pump casing. <P>SOLUTION: The vertical shaft pump includes an impeller 10, a rotary shaft 6 connected to the impeller 10, the pump casing 2 accommodating the impeller 10 and the rotary shaft 6, the submerged bearing 12 rotatbly bearing the rotary shaft 6, a displacement measuring device 30 measuring the radial displacement of the rotary shaft 6, and a monitoring device 31 monitoring the wear of the submerged bearing based on measurement value of the displacement measuring device 30. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a vertical shaft pump for pumping liquids such as river water and drainage, and a submerged bearing monitoring method used for the vertical shaft pump.

  FIG. 1 is a schematic view showing a general vertical shaft pump. As shown in FIG. 1, the vertical shaft pump is installed on the pump installation floor 500 in the upper part of the water tank, and a casing 506 that houses the impeller 504 is suspended via the suspension pipe 502. Such a vertical shaft pump is operated in a state in which the underwater bearing 508 is immersed in water, and the underwater bearing 508 is gradually worn as the usage time elapses. Therefore, the vertical shaft pump is periodically inspected to check the wear state of the underwater bearing 508, and the underwater bearing 508 is repaired or replaced as necessary.

  Wear of the underwater bearing 508 causes abnormal vibration of the pump, and eventually causes a pump failure (unusable). For this reason, the inspection of the underwater bearing 508 is one of the important inspection items. Generally, the maintenance interval for underwater bearings is about 10 years. Therefore, once every 10 years, the casing 506 is disassembled to expose the underwater bearing 508, the wear amount of the underwater bearing 508 is measured using a clearance gauge or the like, and whether or not the underwater bearing 508 should be replaced is determined. to decide.

  As a method of disassembling the vertical shaft pump, there is a method of pulling up the pump using an overhead crane. However, this method is expensive and requires a long time for inspection. For example, when an upright shaft pump is lifted by using an overhead crane, a crane operator is also required, so that considerable work costs are required for the lifting. In addition, it can be said that lifting a heavy pump is dangerous work.

  In addition, after checking and maintaining the vertical pump, it is necessary to reassemble the vertical pump. This assembling work includes steps of centering the drive source and the pump rotating shaft and trial operation of the vertical shaft pump, and requires a considerable number of days. Furthermore, depending on the pump station, it is necessary to keep the necessary amount of water drained even at the time of inspection. During the inspection period, it is necessary to secure a drainage capacity by installing a temporary pump.

  Therefore, as disclosed in Patent Documents 1 to 4 below, a method for detecting the wear of the underwater bearing without pulling up the pump has been proposed. For example, in Patent Document 1, a dummy member is provided adjacent to an underwater bearing, an electric current is passed through a conductive wire embedded therein, and it is detected that the conductive wire is disconnected due to wear of the dummy member. A method for detecting wear of a bearing is disclosed. However, the life of underwater bearings is generally as long as 10 years or more, and the inside of the pump is usually filled with liquid, so that the conductor itself may corrode and break.

  Patent Documents 2 and 3 disclose techniques for estimating the wear amount of a bearing by measuring indirect physical quantities such as air flow rate, pressure, and vibration value. However, these techniques estimate the amount of wear of the bearing by calculation, and are not reliable in determining an accurate bearing replacement time. In this regard, with the method described in Patent Document 1, it is possible to quantitatively grasp the amount of wear of the underwater bearing and accurately determine the replacement time. However, the number of times the wear of the underwater bearing is detected is limited to 1 degree, and if the wear of the underwater bearing is erroneously detected for some reason, the pump is unnecessarily pulled up.

  Patent Document 4 discloses a method of detecting the wear of an underwater bearing adjacent to a conductor by electrically conducting the conductors by contact between the rotating shaft and the conductor. According to this method, when the pump is operated when the underwater bearing is worn, the conductors are electrically connected to each other due to the swing of the pump rotating shaft, so that the wear of the underwater bearing can be detected any number of times. However, since the conducting wire connected to the conductor is disposed in water, there is a possibility that the wear of the underwater bearing may not be detected due to defects such as corrosion or disconnection of the conducting wire itself.

JP 2006-161790 A JP 2004-218578 A Japanese Patent No. 3567140 JP 2008-75625 A

  The present invention has been made in view of the above-described conventional problems, and can detect wear of a submerged bearing with high reliability without disassembling the pump casing and accurately monitor the wear of the submerged bearing. It is an object of the present invention to provide a vertical shaft pump having a mechanism capable of doing this. Moreover, an object of this invention is to provide the monitoring method of the underwater bearing used for this vertical shaft pump.

  In order to achieve the above-described object, one embodiment of the present invention includes an impeller, a rotating shaft connected to the impeller, a pump casing that houses the impeller and the rotating shaft, and the rotating shaft. A submersible bearing that is freely supported, at least one displacement measuring device that measures a radial displacement of the rotating shaft, and a monitoring device that monitors wear of the submerged bearing based on a measurement value of the displacement measuring device. This is a vertical shaft pump characterized by that.

In a preferred aspect of the present invention, the monitoring device is configured such that the number of times the measured value exceeds a predetermined threshold within a predetermined unit time, or the accumulated time that the measured value exceeds the threshold is a predetermined time. It is characterized by determining whether it exceeded the reference value.
In a preferred aspect of the present invention, the monitoring device is configured to issue an alarm when the number of times or the accumulated time exceeds the predetermined reference value.

In a preferred aspect of the present invention, the threshold is operated with the temporary bearing worn or imitating the worn state attached to the vertical pump instead of the submersible bearing, and the vertical pump installed in the suction water tank. It is sometimes a radial displacement of the rotating shaft measured by the displacement measuring device.
In a preferred aspect of the present invention, the monitoring device stores a radial displacement of the rotating shaft measured when the underwater bearing is not worn as a normal value.

In a preferred aspect of the present invention, the monitoring device stores the measurement value and an operation time of the vertical pump when the measurement value is acquired, and an approximate curve from the plurality of the stored measurement values and operation time. And the operation time for the radial displacement of the rotating shaft to reach a predetermined threshold value is estimated from the approximate curve.
In a preferred aspect of the present invention, an outer bearing that rotatably supports the rotating shaft is disposed outside the pump casing, and the rotating shaft is supported only by the underwater bearing and the outer bearing, The underwater bearing is arranged below the impeller.

  Another aspect of the present invention includes an impeller, a rotating shaft coupled to the impeller, a pump casing that houses the impeller and the rotating shaft, a submerged bearing disposed below the impeller, An outer bearing disposed outside the pump casing, wherein the rotating shaft is supported by the submersible bearing and the outer bearing alone, and is a method for monitoring the submerged bearing of a vertical shaft pump, which is worn or A temporary bearing imitating the worn state is attached to the vertical pump instead of the submersible bearing, and the displacement in the radial direction of the rotary shaft is measured with a displacement measuring instrument when the vertical pump is installed in the suction water tank. The measured radial displacement of the rotary shaft is stored as a threshold value, and the radial displacement of the rotary shaft when supported by the underwater bearing is measured by the displacement measuring instrument. Characterized by monitoring the wear of the water bearing by comparing the measured value of the displacement measuring device and the said threshold value.

  The radial displacement of the rotating shaft during rotation increases with wear of the underwater bearing. Accordingly, the wear of the underwater bearing can be accurately monitored by directly measuring the displacement in the radial direction of the rotating shaft supported by the underwater bearing (that is, the magnitude of the swinging of the rotating shaft). Further, based on the obtained displacement of the rotating shaft, it is possible to estimate the tendency of wear of the underwater bearing, the replacement time of the underwater bearing, and the like.

It is a schematic diagram which shows a general vertical shaft pump. It is sectional drawing which shows the whole structure of the vertical shaft pump which concerns on one Embodiment of this invention. It is a typical top view which shows arrangement | positioning of two displacement sensors. It is a schematic diagram explaining the motion of the rotating shaft currently supported by the outer bearing and the underwater bearing. FIG. 5A is a graph showing the displacement of the rotating shaft measured when the underwater bearing is not worn or less worn, and FIG. 5B is a state where the underwater bearing is worn to an allowable limit. It is a graph which shows the displacement of the measured rotating shaft. FIGS. 6A and 6B are waveform graphs showing only the displacement in the X direction or Y direction of the rotation axis along the time axis. It is a schematic diagram which shows the alerting | reporting apparatus of a monitoring apparatus. It is a flowchart for demonstrating the alerting | reporting operation | movement of a monitoring apparatus. FIG. 9A shows a Lissajous figure representing a normal state obtained when the underwater bearing is not worn, and FIG. 9B shows the wear obtained when the underwater bearing is worn. The Lissajous figure showing a state is shown, and FIG.9 (c) shows the Lissajous figure acquired during the drainage operation of the vertical shaft pump. It is a figure which shows the preferable arrangement position of an underwater bearing. It is a graph which shows the relationship between the displacement of the rotating shaft memorize | stored in the monitoring apparatus, and the operation time of a vertical shaft pump.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 2 is a cross-sectional view showing the overall configuration of a vertical shaft pump according to an embodiment of the present invention.
As shown in FIG. 2, the vertical shaft pump includes an impeller casing 1 having a suction bell mouth 1 a and a pump bowl 1 b, a suspension pipe 3 that suspends the impeller casing 1 in a suction water tank 5, and an upper end of the suspension pipe 3. A discharge curved pipe 4 to be connected, an impeller 10 accommodated in the impeller casing 1, and a rotating shaft (vertical axis) 6 to which the impeller 10 is fixed are provided. The suspension pipe 3 extends downward through an insertion hole 24 formed in the pump installation floor 22 at the upper part of the suction water tank 5, and is connected to the pump installation floor 22 via an installation base 23 provided at the upper end of the suspension pipe 3. Fixed. The rotary shaft 6 extends in the vertical direction through the discharge curved pipe 4, the suspension pipe 3, and the impeller casing 1. The pump casing 2 includes an impeller casing 1, a suspension pipe 3, and a discharge curved pipe 4.

  The suction bell mouth 1a opens downward, and the upper end of the suction bell mouth 1a is fixed to the lower end of the pump bowl 1b. The impeller 10 is fixed to the lower end of the rotating shaft 6, and the impeller 10 and the rotating shaft 6 rotate integrally. A plurality of guide vanes 14 are arranged above the impeller 10 (discharge side). These guide vanes 14 are fixed to the inner peripheral surface of the pump bowl 1b. The rotating shaft 6 is rotatably supported by an outer bearing 11 and an underwater bearing 12. The underwater bearing 12 is accommodated in the pump bowl 1 b and is located above the impeller 10. The support member 7 that supports the underwater bearing 12 is fixed to the inner surface of the bowl bush 13, and the bowl bush 13 is supported by the impeller casing 1 via a guide vane 14. The outer bearing 11 is a rolling bearing such as a ball bearing, and the underwater bearing 12 is a so-called sliding bearing that is provided in the water contact portion and slides into contact with the rotating shaft 6. Reference numeral 19 denotes a handhole.

  The rotary shaft 6 protrudes upward from the discharge curved pipe 4 and is connected to a drive source 18. When the impeller 10 is rotated by the drive source 18 via the rotating shaft 6, the water (handling liquid) in the suction water tank 5 is sucked from the suction bell mouth 1 a, and the pump bowl 1 b, the suspension pipe 3, and the discharge curved pipe 4. And then transferred to the discharge pipe 20. During operation of the vertical shaft pump, the impeller casing 1 that houses the impeller 10 is positioned below the liquid level.

  The outer bearing 11 is arranged outside the discharge curved pipe 4. A bearing casing 25 is fixed to the outer surface of the discharge curved pipe 4, and the outer bearing 11 is disposed in the bearing casing 25. A notch 25a is formed in the bearing casing 25, and two displacement sensors 30, 30 are provided close to the notch 25a (only one displacement sensor 30 is shown in FIG. 2). FIG. 3 is a schematic plan view showing the arrangement of the two displacement sensors 30, 30. As shown in FIG. 3, the displacement sensors 30, 30 are arranged so as to be orthogonal to each other. That is, one of the displacement sensors 30 and 30 measures the displacement of the rotating shaft 6 in the X direction, and the other measures the displacement of the rotating shaft 6 in the Y direction. The displacement sensors 30, 30 are non-contact type displacement measuring instruments, and measure the radial displacement of the rotating shaft 6 exposed through the notch 25a. The positions of the displacement sensors 30 and 30 are below the outer bearing 11 and above the pump installation floor 22.

  The displacement sensors 30, 30 are connected to the monitoring device 31, and the measured values of the displacement sensors 30, 30 (that is, the radial displacement of the rotating shaft 6) are sent to the monitoring device 31. The monitoring device 31 stores the measurement values from the displacement sensors 30 and 30 and monitors the wear amount of the underwater bearing 12 based on the measurement values. FIG. 4 is a schematic diagram for explaining the movement of the rotary shaft 6 supported by the outer bearing 11 and the underwater bearing 12. In FIG. 4, only one of the two displacement sensors 30, 30 is shown. In this embodiment, only one underwater bearing 12 is provided in the pump casing 2, and the rotating shaft 6 is supported by the underwater bearing 12 and the outer bearing 11 provided outside the pump casing 2. Yes. As shown in FIG. 4, when the underwater bearing 12 is worn, the rotating shaft 6 swings according to the amount of wear. The magnitude of the swing around the rotary shaft 6 can be expressed as a radial displacement of the rotary shaft 6. Therefore, the radial displacement of the rotating shaft 6 is a value that directly reflects the degree of wear of the underwater bearing 12.

  The monitoring device 31 stores the measured values of the displacement sensors 30 and 30 and creates a graph representing the displacement of the rotating shaft 6 based on the measured values. FIG. 5A is a graph showing the displacement of the rotating shaft measured when the underwater bearing is not worn or less worn, and FIG. 5B is a state where the underwater bearing is worn to an allowable limit. It is a graph which shows the displacement of the measured rotating shaft. In the graphs shown in FIGS. 5A and 5B, the horizontal axis is the displacement in the X direction of the rotating shaft 6, the vertical axis is the displacement in the Y direction of the rotating shaft 6, and the X direction and Y that are orthogonal to each other. The Lissajous figure obtained by synthesizing the vibration of the rotating shaft 6 in the direction is shown. The X direction and the Y direction are directions perpendicular to the rotation axis 6. From the Lissajous figures shown in FIGS. 5A and 5B, it can be seen that the rotating shaft 6 is greatly displaced when the underwater bearing 12 is worn. One displacement sensor may be installed, or the displacement in the radial direction of the rotating shaft 6 may be measured by one displacement sensor 30. In this case as well, a graph representing the displacement of the rotating shaft 6 is similarly created by the monitoring device 31. FIGS. 6A and 6B are waveform graphs showing only the displacement in the X direction or the Y direction of the rotating shaft 6 measured by one displacement sensor along the time axis. Thus, the waveform graph represented along the time axis may be created to determine the progress of the wear state of the underwater bearing 12.

  As can be seen from the schematic diagram of FIG. 4, the displacement sensors 30 and 30 (only one displacement sensor 30 is shown in FIG. 4) must be installed between the outer bearing 11 and the underwater bearing 12. However, it is preferable not to submerge the displacement sensors 30 and 30 from the viewpoint of guaranteeing the operation of the displacement sensors 30 and 30. As shown in FIG. 2, in this embodiment, the displacement sensors 30, 30 are arranged outside the pump casing 2 and above the pump installation floor 22. Since the displacement sensors 30, 30 are disposed above the pump installation floor 22, the displacement sensors 30, 30 can be easily inspected, calibrated, and repaired. If the displacement sensor is disposed below the pump installation floor 22 and is submerged in the water, it is necessary to pull up the vertical shaft pump for inspection or repair of the sensor. Such a lifting operation can be eliminated, and a state where the vertical pump becomes inoperable can be avoided, so that a highly reliable vertical pump can be obtained.

  Since the magnitude of the vibration of the rotating shaft 6 changes according to the amount of wear of the underwater bearing 12, the radial displacement of the rotating shaft 6 can be said to be a value that directly reflects the amount of wear of the underwater bearing 12. Therefore, the wear of the underwater bearing 12 can be accurately detected and monitored by directly measuring the radial displacement of the rotary shaft 6 by the displacement sensors 30 and 30. Moreover, according to this embodiment, it is possible to monitor the amount of wear of the underwater bearing 12 without pulling up the vertical shaft pump from the suction water tank 5, and an economical monitoring system for the underwater bearing 12 can be constructed. In addition, the displacement measurement of the rotating shaft 6 and the wear monitoring of the underwater bearing 12 are performed by closing the discharge valve (not shown) provided in the discharge pipe 20 when the vertical shaft pump is actually performing the drainage operation. Or any operation pattern when performing a dry operation without draining.

  As shown in FIG. 7, the monitoring device 31 includes a notification device 32, and is configured to issue an alarm based on the measured values of the displacement sensors 30 and 30 (displacement in the radial direction of the rotating shaft 6). . A predetermined common threshold value is set in advance for the measurement values of the displacement sensors 30, 30, and the number of times the measurement value exceeds the threshold value within a predetermined unit time, or the measurement value exceeds the threshold value. When the accumulated time exceeds a predetermined reference value, an alarm (alarm sound and / or warning display) is issued from the alarm device 32. The threshold value is a value corresponding to the allowable limit of wear of the underwater bearing 12, and is a value indicating the replacement time of the underwater bearing 12.

  FIG. 8 is a flowchart for explaining the reporting operation of the monitoring device 31. When the operation of the vertical shaft pump is started, the displacement in the radial direction of the rotary shaft 6 is measured by the displacement sensors 30 and 30 (step 1). The measured value is sent from the displacement sensors 30, 30 to the monitoring device 31. The monitoring device 31 compares the measured value with a predetermined threshold value and determines whether or not the measured value is larger than the threshold value (step 2). If the measured value is less than or equal to the threshold value, the process flow returns to step 1. On the other hand, when the measured value is larger than the threshold value, the count is incremented by one, or the time when the measured value exceeds the threshold value is integrated (step 3). The monitoring device 31 determines whether the measured value exceeds the threshold value within a unit time (count) or whether the accumulated time exceeds a predetermined reference value (step 4). When the number of times per unit time or the accumulated time exceeds the reference value, an alarm is issued (step 5). On the other hand, when the number of times per unit time or the accumulated time is equal to or less than the reference value, the processing flow returns to step 1.

  Since the number of times the measured value exceeds the threshold value within the unit time is counted, even if the rotary shaft 6 is momentarily displaced due to dust or the like, no alarm is issued. Therefore, a highly reliable vertical shaft pump can be obtained. Further, according to the present embodiment, it is possible to prevent the vertical shaft pump from being operated in a state where the underwater bearing 12 is worn beyond an allowable limit. Therefore, the underwater bearing 12 can be replaced before a serious failure occurs, so that a more reliable vertical shaft pump is obtained.

  Generally, the vibration mode of the vertical shaft pump varies depending on the amount of pumped water, the total head, the length of the rotary shaft 6, the position and number of bearings, and the installation state of the vertical pump. For this reason, it is difficult to set the above-mentioned threshold appropriately. Therefore, it is preferable that the vertical pump is operated in a state where the vertical pump is actually installed in the suction water tank 5, and the threshold value is determined from the displacement of the rotating shaft 6 during operation. Specifically, a temporary bearing (not shown) that is worn or imitates wear is prepared, this temporary bearing is attached to the vertical pump installed in the suction water tank 5 in place of the submerged bearing 12, and the vertical pump To measure the radial displacement of the rotating shaft 6. The amount of wear of the temporary bearing prepared is an allowable limit for the amount of wear for safely operating the vertical shaft pump. Therefore, the radial displacement of the rotating shaft 6 measured when supported by the temporary bearing is a displacement corresponding to the allowable limit of the wear amount of the underwater bearing 12, and is a value indicating the replacement timing of the underwater bearing 12. is there. Although there is a method of estimating the displacement of the rotating shaft 6 when the underwater bearing 12 is worn by calculation or analysis, the rigidity (deflection) of the rotating shaft 6, the elasticity of the underwater bearing 12, the rattling of the outer bearing 11, It is difficult to accurately reflect various influencing factors such as the installation state of the vertical shaft pump, and it is practically impossible to obtain a satisfactory threshold value.

  The monitoring device 31 registers and stores the measurement value acquired when the temporary bearing is attached as the threshold value described above. The threshold value determined in this way can be said to be an allowable limit of wear of the underwater bearing 12 reflecting a state in which the vertical shaft pump is installed in the suction water tank 5. That is, the determined threshold value is a value reflecting a vibration mode that changes depending on the pumping amount of the vertical shaft pump, the total head, the length of the rotary shaft 6, the position and number of bearings, and the installation state of the vertical pump. Therefore, the replacement time of the underwater bearing 12 can be accurately determined by comparing the radial displacement of the rotary shaft 6 measured by the displacement sensors 30 and 30 with the threshold value.

  In addition to the threshold value obtained using the temporary bearing, it is preferable to measure the displacement in the radial direction of the rotating shaft 6 supported by the underwater bearing 12 when not worn by the displacement sensors 30 and 30. The displacement of the rotating shaft 6 obtained in a state where the underwater bearing 12 is not worn is registered and stored in the monitoring device 31 together with the threshold value as a normal value. Then, the degree of progress of wear of the underwater bearing 12 is determined by comparing the measured values (actual values) of the displacement sensors 30, 30 acquired during operation of the vertical shaft pump with both normal values and threshold values. Can do.

  FIG. 9A shows a Lissajous figure representing a normal state obtained when the underwater bearing is not worn, and FIG. 9B shows the wear obtained when the underwater bearing is worn. The Lissajous figure showing a state is shown, and FIG.9 (c) shows the Lissajous figure acquired during the drainage operation of the vertical shaft pump. In FIG. 9C, a range surrounded by a Lissajous figure indicating a normal state and a Lissajous figure indicating a worn state is a range indicating that the underwater bearing 12 is normal. Therefore, when the measured value (indicated by the dotted line) of the displacement of the rotating shaft 6 represented as the Lissajous figure is within the range surrounded by the Lissajous figure indicating the normal state and the Lissajous figure indicating the worn state, the underwater bearing 12 wear is determined to be within the normal range.

  The monitoring device 31 creates a Lissajous figure shown in FIG. 9C from the measured values of the displacement sensors 30 and 30, and displays the created Lissajous figure on a display unit (not shown). The administrator can determine the degree of wear of the underwater bearing 12 from the displayed Lissajous figure, and can estimate the replacement time of the underwater bearing 12. Instead of the Lissajous figure, as shown in FIGS. 6 (a) and 6 (b), the monitoring device 31 is a waveform graph in which only the displacement of the rotating shaft 6 in the X direction or Y direction is represented along the time axis. May be created.

  FIG. 10 is a diagram showing a preferred arrangement position of the underwater bearing. In the vertical shaft pump described above, the submersible bearing 12 is accommodated in the pump bowl 1b. However, in the example shown in FIG. 10, the submersible bearing 12 is not provided in the pump bowl 1b and is disposed below the impeller 10. Has been. That is, as shown in FIG. 10, the tip portion of the rotating shaft 6 protruding downward from the impeller 10 is supported by the underwater bearing 12. The underwater bearing 12 is supported by a plurality of support members 15 fixed to the inner peripheral surface of the bell mouth 1a, and the underwater bearing 12 is disposed near the suction port of the bell mouth 1a. No other underwater bearing is provided inside the pump casing 2 other than the underwater bearing 12, and the rotary shaft 6 is supported by only two bearings, that is, the outer bearing 11 and the underwater bearing 12 below the impeller 10. ing.

  In this example, the underwater bearing 12 is disposed outside the pump bowl 1b, and further disposed close to the suction port, so that an operator can easily access the underwater bearing 12 from the suction port. Therefore, the underwater bearing 12 can be quickly replaced without pulling up and disassembling the pump casing 2. Specifically, the work time, which was conventionally about one week, can be reduced to about 2-3 hours. Furthermore, since the bearing replacement time can be shortened, the above-described provisional bearing installation and threshold value acquisition operations can be performed during the trial operation when the vertical shaft pump is installed.

  The monitoring device 31 is configured to store the measurement value from the displacement sensor 30 in association with the operation time. Specifically, the monitoring device 31 stores the measurement value of the displacement sensor 30 and the operation time when the measurement value is acquired. The measured value of the displacement sensor 30 stored can be the average of the measured values of the two displacement sensors 30, 30 or the measured value of either of the displacement sensors 30, 30. Furthermore, the monitoring device 31 is configured to create an approximate curve from the obtained plurality of measured values and the corresponding operation time, and to estimate the time when the measured value reaches the above-described threshold value from the approximate curve. FIG. 11 is a graph showing the relationship between the displacement of the rotary shaft 6 stored in the monitoring device 31 and the operation time of the vertical pump. In the graph of FIG. 11, the vertical axis represents the measured value (that is, the radial displacement of the rotating shaft 6), and the horizontal axis represents the operation time of the vertical pump. Since the measured value of the displacement sensor 30 reflects the wear of the underwater bearing 12, the measured value of the displacement sensor 30 increases with the operation time as shown in FIG.

  The monitoring device 31 generates an approximate curve from a plurality of coordinates specified by a plurality of measured values and corresponding operation times, and the displacement of the rotating shaft 6 corresponds to a threshold value (corresponding to an allowable limit of wear of the underwater bearing 12). ) Is determined from the approximate curve. In general, the submersible bearing 12 of the vertical shaft pump is not a general-purpose product and is manufactured exclusively for the vertical shaft pump, so it may take several months to prepare a new submersible bearing. According to the present embodiment, since the replacement time of the underwater bearing 12 can be predicted, a new underwater bearing can be prepared and prepared in advance, and the worn underwater bearing 12 can be quickly replaced with a new underwater bearing. can do. Needless to say, the present invention is similarly applied to an embodiment in which only one displacement sensor is provided. Also in this case, the monitoring device 31 can operate according to the same processing flow.

  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. Therefore, the present invention should not be limited to the described embodiments, but should be the widest scope according to the technical idea defined by the claims.

DESCRIPTION OF SYMBOLS 1 Impeller casing 1a Suction bell mouth 1b Pump bowl 2 Pump casing 3 Suspension pipe 4 Discharge curved pipe 5 Suction water tank 6 Rotating shaft 7 Support member 10 Impeller 10a Impeller hub 10b Impeller 11 Outer bearing 12 Underwater bearing 13 Bowl bush 14 Guide vane 18 Drive source 17 Support member 19 Hand hole 20 Discharge piping 22 Pump installation floor 23 Installation base 24 Pump insertion hole 30 Displacement sensor 31 Monitoring device 32 Alarm device

Claims (8)

Impeller,
A rotating shaft coupled to the impeller;
A pump casing that houses the impeller and the rotating shaft;
An underwater bearing that rotatably supports the rotating shaft;
At least one displacement measuring device for measuring a radial displacement of the rotating shaft;
A vertical shaft pump comprising: a monitoring device that monitors wear of the underwater bearing based on a measurement value of the displacement measuring device.   The monitoring device determines whether the number of times the measured value exceeds a predetermined threshold value within a predetermined unit time, or whether the accumulated time that the measured value exceeds the threshold value exceeds a predetermined reference value. The vertical shaft pump according to claim 1, wherein the vertical shaft pump is configured to determine the above.   The vertical pump according to claim 2, wherein the monitoring device is configured to issue an alarm when the number of times or the accumulated time exceeds the predetermined reference value.   The threshold value is determined by the displacement measuring device when the temporary bearing that is worn or imitated is attached to the vertical pump instead of the submersible bearing, and the vertical pump is installed in the suction water tank. The vertical shaft pump according to claim 2 or 3, characterized in that the displacement is a radial displacement of the rotating shaft measured.   The vertical shaft pump according to claim 4, wherein the monitoring device stores a radial displacement of the rotating shaft measured when the underwater bearing is not worn as a normal value.   The monitoring device stores the measurement value and the operation time of the vertical pump when the measurement value is acquired, generates an approximate curve from the plurality of stored measurement values and operation time, and the approximate curve The vertical shaft pump according to claim 1, wherein an operation time for the radial displacement of the rotary shaft to reach a predetermined threshold is estimated. An outer bearing that rotatably supports the rotating shaft is disposed outside the pump casing,
The rotating shaft is supported only by the underwater bearing and the outer bearing,
The vertical shaft pump according to any one of claims 1 to 6, wherein the underwater bearing is disposed below the impeller. Impeller,
A rotating shaft coupled to the impeller;
A pump casing that houses the impeller and the rotating shaft;
An underwater bearing disposed below the impeller;
An outer bearing disposed outside the pump casing,
The rotating shaft is a monitoring method for the underwater bearing of a vertical shaft pump supported only by the underwater bearing and the outer bearing,
Displacement measurement of the radial displacement of the rotating shaft when a temporary bearing that is worn or imitated is attached to the vertical shaft pump instead of the submerged bearing and the vertical pump is installed in a suction water tank Measured by the instrument,
Storing the measured radial displacement of the rotary shaft as a threshold;
Measuring the displacement in the radial direction of the rotating shaft when supported by the underwater bearing with the displacement measuring instrument;
A method of monitoring an underwater bearing, comprising: monitoring wear of the underwater bearing by comparing a measured value of the displacement measuring device with the threshold value.

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