Oil chamber monitoring device, underwater pump, and oil chamber monitoring method

Abstract

To provide an oil chamber monitoring device which can properly monitor the inside of an oil chamber, a submerged pump and an oil chamber monitoring method.SOLUTION: An oil chamber monitoring device comprises: a pressure sensor 110 for detecting the pressure of an oil chamber 13; a space temperature sensor 120 for detecting a space temperature of the oil chamber 13; an oil temperature sensor 130 for detecting an oil temperature of the oil chamber 13; and calculation means for calculating an oil leakage amount VW or a water immersion amount VW of the oil chamber 13 from displacements of space volumes V1, V1' and oil volumes V2, V2' of the oil chamber at a first time point and a second time point on the basis of first pressure P, a first space temperature T1 and a first oil temperature T2 at the first time point, and second pressure P', a second space temperature T1' and a second oil temperature T2' at the second time point.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to an oil chamber monitoring device, a submersible pump, and an oil chamber monitoring method.

Background Art

[0002] Conventionally, there are submersible pumps used for various purposes such as sewage and drainage. A submersible pump sucks up water and discharges it by rotating a main shaft with a motor, and a mechanical seal (shaft sealing device) is attached to the main shaft to prevent water from entering the motor. Further, an oil chamber filled with oil is provided near the main shaft, and the oil is supplied to the mechanical seal to lubricate its sliding surface, contributing to the quality and reliability of the submersible pump.

[0003] Generally, if oil leakage or the like occurs, it may lead to problems with the submersible pump, so it is important to monitor the amount of oil enclosed in the oil chamber. For example, in Patent Document 1, a technique related to a pump diagnosis method for detecting a pump failure or its sign is disclosed by measuring the temperature of the lubricating oil flowing through the mechanical seal after the pump operation is stopped and estimating the filling amount of the lubricating oil based on the measured temperature change trend.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the pump diagnosis method described in Patent Document 1, only the filling amount of the lubricating oil is estimated after the pump operation is stopped, and there is a problem that the situation of the oil chamber including oil leakage and flooding in the oil chamber cannot be appropriately monitored.

[0006] Therefore, the present invention has been made in view of the above problems, and one of the objects of the present invention is to provide an oil chamber monitoring device, a submersible pump, and an oil chamber monitoring method capable of appropriately monitoring an oil chamber.

Means for Solving the Problems

[0007] An oil chamber monitoring device according to an aspect of the present invention is an oil chamber monitoring device that monitors an oil chamber in which oil supplied to a mechanical seal of a submersible pump is enclosed, and includes a pressure sensor that detects the pressure of the oil chamber, a space temperature sensor that detects the space temperature of the oil chamber, an oil temperature sensor that detects the oil temperature of the oil chamber, a first pressure that is the pressure, a first space temperature that is the space temperature, and a first oil temperature that is the oil temperature at a first time point, and a second pressure that is the pressure, a second space temperature that is the space temperature, and a second oil temperature that is the oil temperature at a second time point, and calculation means for calculating an oil leakage amount or a water intrusion amount of the oil chamber from displacements of the space volume and the oil volume of the oil chamber at the first time point and the second time point.

[0008] In the above aspect, the calculation means may calculate the space volume of the oil chamber at the second time point with respect to the first time point using the first pressure and the first space temperature, and the second pressure and the second space temperature, and calculate the oil volume of the oil chamber at the second time point with respect to the first time point using the first oil temperature and the second oil temperature.

[0009] In the above aspect, the calculation means may calculate an oil leakage amount or a water intrusion amount of the oil chamber based on the space volume of the oil chamber at the second time point with respect to the first time point, the oil volume of the oil chamber at the second time point with respect to the first time point, and the volume of the oil chamber.

[0010] In the above aspect, the space volume of the oil chamber may be calculated using Boyle's law.

[0011] In the above aspect, the oil volume of the oil chamber may be calculated based on the oil expansion coefficient of the oil.

[0012] In the above aspect, the first time point may be when the submersible pump is stopped, and the second time point may be when the submersible pump is operating.

[0013] In the above aspect, an actual oil filling amount calculating means for calculating the actual oil filling amount actually enclosed in the oil chamber based on the pressure detected by the pressure sensor on the assumption that a predetermined amount of oil is enclosed in the oil chamber may be further provided for the oil volume of the oil chamber.

[0014] In the above aspect, the actual oil filling amount may be calculated according to a predetermined temperature change.

[0015] In the above aspect, the actual oil filling amount may be calculated while the submersible pump is stopped.

[0016] The submersible pump according to one aspect of the present invention includes the above oil chamber monitoring device, a motor, a rotating shaft that rotates by driving the motor, and an impeller that rotates in a pump chamber as the rotating shaft rotates, draws liquid from a suction port, and generates a flow toward a discharge port.

[0017] An oil chamber monitoring method according to one aspect of the present invention is an oil chamber monitoring method executed by an oil chamber monitoring device that monitors an oil chamber in which oil supplied to a mechanical seal of a submersible pump is enclosed, and includes obtaining the pressure of the oil chamber detected by a pressure sensor, obtaining the space temperature of the oil chamber detected by a space temperature sensor, obtaining the oil temperature of the oil chamber detected by an oil temperature sensor, the first pressure that is the pressure, the first space temperature that is the space temperature, and the first oil temperature that is the oil temperature at a first time point, and the second pressure that is the pressure, the second space temperature that is the space temperature, and the second oil temperature that is the oil temperature at a second time point, and calculating an oil leakage amount or a water ingress amount of the oil chamber from the displacement of the space volume and the oil volume of the oil chamber at the first time point and the second time point.

Effect of the Invention

[0018] According to the present invention, it is possible to provide an oil chamber monitoring device, a submersible pump, and an oil chamber monitoring method capable of appropriately monitoring an oil chamber.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Modes for Carrying Out the Invention

[0020] Hereinafter, preferred embodiments of the present invention will be specifically described with reference to the accompanying drawings. It should be noted that each of the embodiments described below is merely a specific example for carrying out the present invention and does not limit the interpretation of the present invention. Also, for ease of understanding of the description, the same reference numerals are attached to the same components in each drawing as much as possible, and duplicate descriptions may be omitted.

[0021] <First Embodiment> [Regarding the Structure of the Submersible Pump] Figure 1 is a structural diagram showing an overview of the underwater pump 10 according to the first embodiment of the present invention. As shown in Figure 1, the underwater pump 10 has a motor 11, a rotating shaft 12, an oil chamber 13, a mechanical seal (shaft sealing device) 14, a pump chamber 15, and an impeller 16. Other members such as bearings and oil lifters are also included, but here, the description of the detailed configuration is omitted.

[0022] The motor 11 is configured to rotationally drive the impeller 16 connected to the tip of the rotating shaft 12 via the rotating shaft 12. For example, the motor 11 has a stator (coil) and a rotor, and rotates the rotor by the magnetic field generated in the stator.

[0023] The rotating shaft 12 is arranged so as to extend from the motor 11 through the oil chamber 13 to the pump chamber 15, and the impeller 16 is arranged at the tip thereof. When the motor 11 is driven, the rotating shaft 12 is configured to transmit the driving force (torque) of the motor 11 to the impeller 16.

[0024] The oil chamber 13 is arranged between the motor 11 and the pump chamber 15, and oil is enclosed in the oil chamber 13. A mechanical seal 14 is arranged in the oil chamber 13, and the mechanical seal 14 is annularly attached so as to surround the outer periphery of the rotating shaft 12 passing through the oil chamber 13.

[0025] The mechanical seal 14 has an oil film forming portion on the sliding surface, thereby suppressing the ingress of water from the pump chamber 15 into the oil chamber 13 and suppressing the oil in the oil chamber 13 from flowing into the motor 11 (motor chamber). Also, the sliding surface is lubricated by the oil filled in the oil chamber 13 and cooled so as not to seize.

[0026] In the pump chamber 15, an impeller 16 is arranged. When the motor 11 is driven, the impeller 16 connected to the tip of the rotating shaft 12 via the rotating shaft 12 is rotationally driven. Then, with the rotational drive of the impeller 16, the pump chamber 15 is configured such that liquid flows in from the suction port and liquid flows out from the discharge port.

[0027] The impeller 16 is attached to the tip of the rotating shaft 12 and is arranged in the pump chamber 15. As described above, when the motor 11 is driven, the impeller 16 is rotationally driven via the rotating shaft 12, draws in liquid from the suction port, generates a flow toward the discharge port, and is configured such that liquid flows out from the discharge port.

[0028] Furthermore, in the submersible pump 10, as an oil chamber monitoring device for monitoring the oil chamber 13, a pressure sensor 110, a space temperature sensor 120, and an oil temperature sensor 130 are arranged, and a control unit (calculation means) for processing the data detected by them is configured.

[0029] [Regarding the oil chamber monitoring device] Next, the configuration and function of the oil chamber monitoring device will be described. FIG. 2 is a diagram schematically showing the state of the oil chamber. In FIG. 2, the oil chamber is shown in two states, for example, (A) when the submersible pump 10 is stopped (stopped state) and (B) when the submersible pump 10 is operating (operating state).

[0030] At these two time points (states), the pressure sensor 110 detects the pressure in the oil chamber, the space temperature sensor 120 detects the space temperature in the oil chamber, and the oil temperature sensor 130 detects the oil temperature in the oil chamber. Then, based on the data detected respectively, for example, the control unit (calculation means) in the oil chamber monitoring device calculates the oil leakage amount or water ingress amount in the oil chamber from the displacement of the space volume and oil volume in the oil chamber at the time of stop and operation. The calculation process will be described in detail below.

[0031] (A) At the stop (the first point in time), the first pressure P which is the pressure in the oil chamber, the first space temperature T which is the space temperature in the oil chamber 1 , and the first oil temperature T which is the oil temperature in the oil chamber 2 . Further, the oil chamber volume V, the first space volume V 1 and the first oil volume V 2 .

[0032] (B) During operation (the second point in time), the second pressure P' which is the pressure in the oil chamber, the second space temperature T 1 ' and the second oil temperature T 2 ' which is the oil temperature in the oil chamber. Further, the oil chamber volume V, the second space volume V 1 ' and the second oil volume V 2 '.

[0033] For example, by operating the underwater pump 10, the temperature in the oil chamber may rise and the oil enclosed in the oil chamber may expand. However, at (A) the stop and (B) during operation, the oil chamber volume V is constant and satisfies the following (Equation 1) and (Equation 2). Generally, the amount of oil enclosed in the oil chamber is defined, for example, as 80% of the oil chamber volume V at a predetermined oil temperature, and it is advisable to enclose it in accordance with this regulation.

Equation

Equation

[0034] Here, regarding the two points in time (states), using Boyle's law, the following (Equation 3) is satisfied.

Equation

[0035] Also, the second oil volume V 2’ can be obtained using the oil expansion coefficient α. The oil expansion coefficient α is predefined according to factors such as the type of oil enclosed in the oil chamber. Since the oil volume changes in response to temperature changes, for example, the oil volume expands as the temperature rises, here, the oil expansion coefficient α is determined using the first oil temperature T at stop 2 and the second oil temperature T during operation 2 ’ and is expressed as shown in the following (Equation 4).

Equation

[0036] Assuming that the temperature of the oil chamber rises and the oil enclosed in the oil chamber expands from the stop to the operation of the water pump 10, the second oil volume V at operation relative to the stop 2 ’ can be expressed as shown in the following (Equation 5) using the oil expansion coefficient α and the first oil volume V 2 .

Equation

[0037] Substituting the second space volume V 1 ’ (the above (Equation 3)) and the second oil volume V 2 ’ (the above (Equation 5)) into the above (Equation 2), the oil chamber volume V can be expressed as shown in the following (Equation 6).

Equation

[0038] The oil chamber volume V satisfies the relationship of the above (Equation 6) using the first pressure P, the first space temperature T 1 , the first oil temperature T 2 , and the second pressure P’, the second space temperature T 1 ’, the second oil temperature T 2 ’ detected by the pressure sensor 110, the space temperature sensor 120, and the oil temperature sensor 130 at the stop and operation of the water pump 10.

[0039] [Regarding Oil Leakage and Water Ingress in the Oil Chamber] FIG. 3 is a diagram schematically showing the state of the oil chamber to explain monitoring of oil leakage and water ingress in the oil chamber. In FIG. 3, similar to FIG. 2, the oil chamber shows two states, for example, (A) when the submersible pump 10 is stopped (stopped state), and (B) when the submersible pump 10 is operating (operating state).

[0040] Here, assuming that water ingress (ingress water volume V W ) occurs into the oil chamber during (B) operation, the oil chamber volume V will satisfy the following relationship (Equation 7). [Equation]

[0041] Solving the above (Equation 7) for the water ingress volume V W can be shown as follows (Equation 8). [Equation]

[0042] Here, regarding the second space volume V 1 ’ and the second oil volume V 2 ’, similar to the explanation using FIG. 2, substituting the above (Equation 3) and the above (Equation 5) using Boyle's law and the oil expansion coefficient α, the water ingress volume V W can be shown as follows (Equation 9). [Equation]

[0043] And since the oil chamber volume V is preset and constant, as shown in the above (Equation 9), the water ingress volume V W is the first pressure P, the first space temperature T 1 detected by the pressure sensor 110, the space temperature sensor 120, and the oil temperature sensor 130 when the submersible pump 10 is stopped and operating, and the first oil temperature T2 and the second pressure P', the second space temperature T 1 ', and the second oil temperature T 2 ' can be calculated using them.

[0044] Note that when the water ingress volume V W > 0 (the water ingress volume V W is positive), it indicates that there is water ingress into the oil chamber. When the water ingress volume V W < 0 (the water ingress volume V W is negative), it indicates that there is oil leakage from the oil chamber.

[0045] [Regarding the oil chamber monitoring method] Next, the oil chamber monitoring method executed by the oil chamber monitoring device for monitoring the oil chamber of the submersible pump 10 will be specifically and in detail described.

[0046] FIG. 4 is a flowchart showing the processing flow of the oil chamber monitoring method M100 executed by the oil chamber monitoring device included in the submersible pump 10 according to the first embodiment of the present invention. As shown in FIG. 4, the oil chamber monitoring method M100 includes steps S110 to S140, and each step is executed by a control unit (processor) included in the oil chamber monitoring device.

[0047] In step S110, when the submersible pump 10 is stopped (the first time point), the pressure sensor 110 detects the pressure in the oil chamber (the first pressure), the space temperature sensor 120 detects the space temperature in the oil chamber (the first space temperature), and the oil temperature sensor 130 detects the oil temperature in the oil chamber (the first oil temperature).

[0048] In step S120, when the submersible pump 10 is operating (the second time point), the pressure sensor 110 detects the pressure in the oil chamber (the second pressure), the space temperature sensor 120 detects the space temperature in the oil chamber (the second space temperature), and the oil temperature sensor 130 detects the oil temperature in the oil chamber (the second oil temperature).

[0049] Here, during the operation of the submersible pump 10 (the second time point), it may be the timing when a predetermined temperature change (for example, a 10°C rise, etc.) has occurred after the submersible pump 10 starts operating. Here, the predetermined temperature change may be a temperature change in the space temperature of the oil chamber, a temperature change in the oil temperature, or even a combination of these.

[0050] In step S130, the control unit (calculation means) calculates the space volume of the oil chamber at the second time point with respect to the first time point based on the first pressure and the first space temperature detected in step S110 and the second pressure and the second space temperature detected in step S120. As a specific example, the control unit calculates the second space volume V 1 ’ using the ideal gas law according to the above (Equation 3).

[0051] Also, the control unit (calculation means) calculates the oil volume of the oil chamber at the second time point with respect to the first time point based on the first oil temperature detected in step S110 and the second oil temperature detected in step S120. As a specific example, the control unit calculates the second oil volume V 2 ’ using the oil expansion coefficient related to the oil temperature change according to the above (Equation 5).

[0052] In step S140, the control unit (calculation means) calculates the oil leakage amount or the water intrusion amount in the oil chamber based on the space volume and the oil volume of the oil chamber at the second time point calculated in step S130. As a specific example, the control unit calculates the oil leakage amount V W (when <0) or the water intrusion amount V W (when >0) in the oil chamber from the first time point to the second time point using the above (Equation 9).

[0053] As described above, according to the underwater pump 10 according to the first embodiment of the present invention, the oil chamber monitoring device detects the pressure of the oil chamber by the pressure sensor 110, the space temperature of the oil chamber by the space temperature sensor 120, and the oil temperature of the oil chamber by the oil temperature sensor 130 when the underwater pump 10 is stopped and operating. Then, based on the respectively detected data, for example, the control unit (calculation means) in the oil chamber monitoring device calculates the oil leakage amount or the water intrusion amount of the oil chamber from the displacement of the space volume and the oil volume of the oil chamber when stopped and when operating, and can appropriately monitor the inside of the oil chamber.

[0054] In addition, in this embodiment, the data was respectively detected by the pressure sensor 110, the space temperature sensor 120, and the oil temperature sensor 130 with the stop time of the underwater pump 10 as the first time point and the operation time as the second time point, but the detection timing is not limited to this. For example, with two timings at the stop time of the underwater pump 10 as the first time point and the second time point, the oil leakage and water intrusion of the oil chamber before the operation of the underwater pump 10 may be confirmed, or with two timings during the operation of the underwater pump 10 as the first time point and the second time point, the oil leakage and water intrusion of the oil chamber at any point during the operation of the underwater pump 10 may be confirmed. Also, if the first time point and the second time point are continuously set, the oil leakage and water intrusion of the oil chamber can also be continuously monitored.

[0055] <Second Embodiment> Next, in the second embodiment of the present invention, calculating the actual amount of oil enclosed in the oil chamber will be described. The basic configuration of the underwater pump according to this embodiment is the same as that of the underwater pump 10 described in the first embodiment of the present invention, and here, mainly, the differences from the first embodiment of the present invention will be described.

[0056] Generally, the amount of oil enclosed in the oil chamber is defined, for example, as about 80% of the oil chamber volume V at a predetermined oil temperature, and is enclosed in accordance with this regulation. However, it is conceivable that an appropriate amount of oil is not enclosed, or that even when an appropriate amount of oil is enclosed, there is actually an error.

[0057] In the oil chamber monitoring device included in the underwater pump 10 according to the second embodiment of the present invention, an oil actual filling amount calculating means (not shown) for calculating the actual amount of oil filled in the oil chamber is further provided.

[0058] The oil actual filling amount calculating means calculates the actual amount of oil filled based on the pressure in the oil chamber detected by the pressure sensor 110, assuming that a preset fixed amount of oil has been filled in the oil chamber with respect to the oil volume of the oil chamber.

[0059] [Regarding the actual amount of oil filled] FIG. 5 is a diagram schematically showing the state of the oil chamber in order to explain the calculation of the actual amount of oil filled in the oil chamber. In FIG. 5, the oil chamber is shown in two states, for example, (A) when the underwater pump 10 is stopped (stopped state), and (B) when the underwater pump 10 is operating (operating state).

[0060] (A) At the stop (first point in time), the first pressure P which is the pressure in the oil chamber, the first space temperature T which is the space temperature in the oil chamber 1 , and the first oil temperature T which is the oil temperature in the oil chamber 2 . Further, it is the oil chamber volume V. And as the actual amount of oil filled in the oil chamber, it is the first oil volume X, and the first space volume V X at that time.

[0061] (B) During operation (second point in time), the second pressure P which is the pressure in the oil chamber X , the second space temperature T which is the space temperature in the oil chamber 1 ’, and the second oil temperature T which is the oil temperature in the oil chamber 2 ’. Further, it is the oil chamber volume V. And it is assumed to be the second space volume V X ’ and the second oil volume X’.

[0062] FIG. 6 is a graph showing the transition of the pressure in the oil chamber detected by the pressure sensor 110 in the case of the actual oil filling amount actually enclosed in the oil chamber and the pressure in the oil chamber assuming that a predetermined amount of oil is enclosed in the oil chamber.

[0063] In FIG. 6, as shown in FIG. 5, the measured pressure 601 detected by the pressure sensor 110 in the case of the first oil volume X enclosed in the oil chamber at the first time point, and as shown in FIG. 2, the first oil volume V enclosed in the oil chamber at the first time point 2 is shown, assuming a case (for example, taking 80% of the volume V of the oil chamber as a predetermined amount), the theoretical pressure 602 calculated in advance.

[0064] Also, the first space temperature T at the time of stopping the underwater pump 10 (first time point) 1 and the first oil temperature T 2 are such that when starting the operation of the underwater pump 10 and at the time of temperature change (here, a 10 ° C rise) from the first space temperature T 1 or the first oil temperature T 2 taking the time of temperature change as the operation time of the underwater pump 10 (second time point), the measured pressure 601 at that time is the second pressure P X and the theoretical pressure 602 is the second pressure P'.

[0065] In other words, since the actual oil filling amount actually enclosed in the oil chamber has an error from, for example, the oil amount taking 80% of the volume V of the oil chamber as a predetermined amount, there is a difference between the measured pressure detected by the pressure sensor 110 and the theoretical pressure. The differential pressure ΔP between the measured pressure (second pressure P X ) at the second time point and the theoretical pressure (second pressure P') can be expressed as shown in the following (Equation 10).

Equation

[0066] Furthermore, regarding the two time points (states) shown in FIG. 2, using the Boyle's law, the second pressure P' in the theoretical pressure 602 satisfies the following (Equation 11). [Number]

[0067] Also, regarding the two time points (states) shown in FIG. 5, using Boyle's law, the second pressure P at the measured pressure 601 X satisfies the following (Equation 12). [Number]

[0068] Substituting the second pressure P' as the theoretical pressure (the above (Equation 11)) and the second pressure P as the measured pressure into the above (Equation 10), the differential pressure ΔP can be expressed as the following (Equation 13). X (The above (Equation 12)), the differential pressure ΔP can be shown as the following (Equation 13). [Number]

[0069] Furthermore, regarding the two time points (states) shown in FIG. 5, taking the displacement of the space volume of the oil chamber as the above (Equation 13), and solving for the first space volume V X / the second space volume V X ', it can be shown as the following (Equation 14). [Number]

[0070] Thus, as the displacement of the space volume of the oil chamber, the first space volume V X / the second space volume V X ' is the first space temperature T detected by the space temperature sensor 120 at the two time points (states) shown in FIG. 5 1 , the second space temperature T 1 ', and the first pressure P detected by the pressure sensor 110. Furthermore, assuming that 80% of the volume V of the oil chamber is filled with oil as a predetermined amount at the two time points (states) shown in FIG. 2, the first space volume V 1 and the second space volume V1 can be calculated using

[0071] Then, the oil filling amount calculating means calculates the actual oil filling amount X filled in the oil chamber shown in FIG. 5.

[0072] First, at the first point in time, since the oil in the oil chamber is before expansion, the oil chamber volume V satisfies the following (Equation 15).

Equation

[0073] Next, when the operation of the submersible pump 10 is started, the temperature of the oil chamber rises and the oil filled in the oil chamber expands. The oil chamber volume V at the second point in time can be expressed as the following (Equation 16) using the second space volume V X ’ and the second oil volume X’. Note that the second oil volume X’ can be expressed using the oil expansion coefficient α.

Equation

[0074] Solving the above (Equation 15) for the first space volume V X yields the following (Equation 17).

Equation

[0075] Solving the above (Equation 16) for the second space volume V X ’ yields the following (Equation 18).

Equation

[0076] From the above (Equation 17) and (Equation 18), the displacement of the space volume of the oil chamber, the first space volume V X / the second space volume V XSolving for ’, it can be shown as in the following (Equation 19). [Equation]

[0077] Then, from the above (Equation 19), the actual oil filling amount X actually filled in the oil chamber can be shown as in the following (Equation 20). [Equation]

[0078] Here, substituting (V X / V X ’) shown in the above (Equation 14) into the above (Equation 20), the actual oil filling amount X can be calculated.

[0079] [Regarding the oil leakage amount and water ingress amount in the oil chamber] As described above, after calculating the actual oil filling amount X actually filled in the oil chamber, the procedure for calculating the oil leakage amount or water ingress amount in the oil chamber will be described.

[0080] The oil leakage amount or water ingress amount in the oil chamber is calculated as the water ingress amount V shown in the above (Equation 9) W . Here, at (A) the stop time (the first time point), the first pressure P which is the pressure in the oil chamber, the first space temperature T 1 which is the space temperature in the oil chamber, and the first oil temperature T 2 which is the oil temperature in the oil chamber, and further, the oil chamber volume V. And, as the actual oil filling amount actually filled in the oil chamber, the first oil volume X (V 2 in the above (Equation 9)), and the first space volume V X at that time (V 1 in the above (Equation 9)) can be shown as the oil chamber volume V - the first oil volume X.

[0081] At (B) the operation time (the second time point), the second pressure P which is the pressure in the oil chamber X(In the above (Equation 9), P’), the second space temperature T which is the space temperature of the oil chamber 1 ’, and the second oil temperature T which is the oil temperature of the oil chamber 2 ’. Further, it is the oil chamber volume V. And let the second space volume V X ’ and the second oil volume X’ be.

[0082] Arranging these in light of the above (Equation 9), the water ingress volume V W (oil leakage V of the oil chamber W ) can be shown as in the following (Equation 21).

Equation

[0083] And, by substituting the oil actually enclosed amount X calculated by the above (Equation 20) into the above (Equation 21), the water ingress volume V W is calculated.

[0084] As described above, according to the submersible pump 10 according to the second embodiment of the present invention, the oil actually enclosed amount calculating means calculates the oil actually enclosed amount X actually enclosed in the oil chamber, and then, in order to calculate the oil leakage amount or the water ingress amount of the oil chamber, the inside of the oil chamber can be monitored more accurately and appropriately.

[0085] Although a predetermined amount is determined as the amount of oil enclosed in the oil chamber, there may be an error in the actually enclosed amount of oil. Even when these errors occur, after calculating the oil actually enclosed amount X actually enclosed in the oil chamber, in order to calculate the oil leakage amount or the water ingress amount of the oil chamber, the inside of the oil chamber can be monitored more accurately and appropriately.

[0086] Note that, as described with reference to FIGS. 5 and 6 in this embodiment, the oil filling amount X was calculated according to a temperature increase of 10°C. However, the present invention is not limited to this, and it may be calculated according to a predetermined temperature change, for example, a temperature increase or decrease such as 5°C, 15°C, or 20°C. If a predetermined temperature change has occurred, it is possible to calculate the oil filling amount X. However, the larger the temperature change, the more appropriate the calculation result can be obtained.

[0087] In addition, in this embodiment, the time when the submersible pump 10 stops is defined as the first time point, and the time when it is operating is defined as the second time point, and the oil filling amount X is calculated when a predetermined temperature change (a temperature increase of 10°C) occurs. However, the present invention is not limited to this. For example, two timings during the stop of the submersible pump 10 may be defined as the first time point and the second time point. If a predetermined temperature change occurs between the first time point and the second time point, the oil filling amount X can be appropriately calculated.

[0088] Furthermore, if a predetermined temperature change (the temperature change between the first time point and the second time point) occurs before the start of operation of the submersible pump 10, the oil filling amount X can be calculated to calculate the oil leakage amount or the water intrusion amount in the oil chamber. As a result, it is possible to confirm whether oil leakage or water intrusion has occurred in the oil chamber before the start of operation of the submersible pump 10.

[0089] Note that, in each embodiment, the pressure in the oil chamber indicates the pressure in the space part of the oil chamber. However, in the oil chamber, the pressure of the oil part (including the liquid part in the case of water intrusion) where pressure equilibrium is achieved with the space part may be detected.

[0090] Each of the embodiments described above is for facilitating the understanding of the present invention and is not for limiting and interpreting the present invention. Each element included in each embodiment, as well as its arrangement, material, conditions, shape, size, etc. are not limited to those illustrated and can be appropriately changed. Also, it is possible to partially substitute or combine the configurations shown in different embodiments.

Description of Reference Numerals

[0091] 10… Water pump, 11… Motor, 12… Rotating shaft, 13… Oil chamber, 14… Mechanical seal (shaft seal device), 15… Pump chamber, 16… Impeller, 110… Pressure sensor, 120… Space temperature sensor, 130… Oil temperature sensor, M100… Oil chamber monitoring method

Claims

1. An oil chamber monitoring device for monitoring an oil chamber filled with oil supplied to a mechanical seal of a submersible pump, comprising: a pressure sensor for detecting the pressure of the oil chamber; a space temperature sensor for detecting the space temperature of the oil chamber; an oil temperature sensor for detecting the oil temperature of the oil chamber; calculating means for calculating the oil leakage amount or water intrusion amount of the oil chamber from the displacement of the space volume and the oil volume of the oil chamber at the first time point and the second time point based on the first pressure which is the pressure, the first space temperature which is the space temperature, and the first oil temperature which is the oil temperature at the first time point, and the second pressure which is the pressure, the second space temperature which is the space temperature, and the second oil temperature which is the oil temperature at the second time point; an oil chamber monitoring device.

2. The calculating means: calculates the space volume of the oil chamber at the second time point with respect to the first time point using the first pressure and the first space temperature, and the second pressure and the second space temperature; calculates the oil volume of the oil chamber at the second time point with respect to the first time point using the first oil temperature and the second oil temperature. The oil chamber monitoring device according to Claim 1.

3. The calculating means calculates the oil leakage amount or water intrusion amount of the oil chamber based on the space volume of the oil chamber at the second time point with respect to the first time point, the oil volume of the oil chamber at the second time point with respect to the first time point, and the volume of the oil chamber. The oil chamber monitoring device according to Claim 2.

4. The space volume of the oil chamber is calculated using Boyle's law. The oil chamber monitoring device according to Claim 1.

5. The oil volume of the oil chamber is calculated based on the oil expansion coefficient of the oil. The oil chamber monitoring device according to Claim 1.

6. The first time point is during the stop of the submersible pump; The second time point is during the operation of the submersible pump. The oil chamber monitoring device according to Claim 1.

7. The oil chamber monitoring device according to Claim 1, further comprising oil actual filling amount calculating means for calculating the actual oil filling amount actually filled in the oil chamber based on the pressure detected by the pressure sensor on the assumption that a preset fixed amount of oil is filled in the oil chamber with respect to the oil volume of the oil chamber. The oil chamber monitoring device according to Claim 1.

8. The actual oil filling amount is calculated according to a predetermined temperature change. The oil chamber monitoring device according to claim 7.

9. The actual oil filling amount is calculated while the underwater pump is stopped. The oil chamber monitoring device according to claim 8.

10. An oil chamber monitoring device according to any one of claims 1 to 9, a motor, a rotating shaft that rotates by driving the motor, and an impeller that rotates in a pump chamber as the rotating shaft rotates, draws in liquid from a suction port, and generates a flow toward a discharge port. An underwater pump.

11. An oil chamber monitoring method executed by an oil chamber monitoring device that monitors an oil chamber in which oil supplied to a mechanical seal of an underwater pump is enclosed, acquiring the pressure of the oil chamber detected by a pressure sensor, acquiring the space temperature of the oil chamber detected by a space temperature sensor, acquiring the oil temperature of the oil chamber detected by an oil temperature sensor, calculating an oil leakage amount or a water intrusion amount of the oil chamber from displacements of the space volume and the oil volume of the oil chamber at the first time point and the second time point based on the first pressure that is the pressure, the first space temperature that is the space temperature, and the first oil temperature that is the oil temperature at the first time point, and the second pressure that is the pressure, the second space temperature that is the space temperature, and the second oil temperature that is the oil temperature at the second time point. An oil chamber monitoring method.

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