Submersible pump

Abstract

To provide a submerged pump which can detect liquid leakage from a shaft seal device at multiple steps.SOLUTION: A submerged pump includes: a motor chamber 3 which houses a motor 2 having a motor shaft 2a; a pump chamber 5 which houses an impeller 4 attached to the motor shaft 2a; a shaft seal device 6 which is provided between the motor chamber 3 and the pump chamber 5 and seals the motor shaft 2a; an oil chamber 7 which is disposed between the motor chamber 3 and the pump chamber 5 to store a lubrication oil of the shaft seal device 6; an overflowing water reservoir part having multiple leaking liquid reservoir parts 8a, 8b provided so that a liquid leaking from the shaft seal device 6 to the motor chamber 3 side sequentially flows thereinto to be stored; and overflowing water detectors 9a, 9b which are respectively provided at the multiple leaking liquid reservoir parts 8a, 8b and detect, at the leaking liquid reservoir parts 8a, 8b, the liquids flowing into the liquid leakage parts 8a, 8b.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a submersible pump for use in fields such as wastewater treatment and civil engineering. [Background technology]

[0002] Conventionally, as an example of this type of submersible pump, as shown in Figure 25, there is known a submersible pump 1 which comprises a motor chamber 3 accommodating a motor 2 having a motor shaft 2a, a pump chamber 5 accommodating an impeller 4 attached to the motor shaft 2a, a shaft seal device 6 which seals the motor shaft 2a and an oil chamber 7 which accommodates seal oil L, a water submersion chamber 8 which is provided between the oil chamber 7 and the motor chamber 3 and which collects liquid (seal oil, water, or a mixture thereof) that leaks from the shaft seal device 6, and two water submersion detectors 9a, 9b which detect liquid that has entered the water submersion chamber 8 from the shaft seal device 6 in two stages (Patent Document 1, etc.).

[0003] The shaft seal 6 prevents water from entering the motor chamber 3 from the pump chamber 5. If water enters the motor chamber 3 from the shaft seal 6 due to aging or other reasons of the shaft seal 6, which is a sliding part, the liquid leaking from the shaft seal 6 is stored in the water flooding chamber 8, and the stored liquid can be detected in two stages by the upper and lower water flooding detectors 9a, 9b. In Fig. 25, the lower water flooding detector 9a is composed of an electrode rod, and the upper water flooding detector 9b is composed of a float switch. The float switch detects the liquid level of the liquid that has entered the water flooding chamber 8, and the electrode rod detects the intrusion of conductive water by measuring the insulation resistance.

[0004] By providing two upper and lower water flooding detectors 9a, 9b, preparations for replacement of the shaft seal device 6 can be made as soon as the lower water flooding detector 9a detects water flooding, and as soon as the upper water flooding detector 9b detects water flooding, the submersible pump can be immediately stopped and the replacement work of the shaft seal device 6 can begin. This enables the shaft seal device 6 to be replaced quickly and the downtime of the submersible pump 1 to be kept as short as possible (Patent Document 1, etc.). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Registered Utility Model No. 3213159 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the conventional submersible pumps described above, the submersible pump requires space in the vertical direction of the submersion chamber in order to detect water submersion at two levels, one above the other, and therefore the submersible pump must be made longer in the vertical direction, making the submersible pump bulky.

[0007] In addition, when flood detection is limited to two stages, it is not possible to detect the changing rate of flooding, and only a warning and shutdown are issued. If the time between the warning and shutdown is short, preparations for part replacement may not be made in time, and the submersible pump may not be able to operate for a long period of time.

[0008] Furthermore, providing multiple water submersion detectors requires wiring to send signals to each water submersion detector, which makes the pump cable thicker, increases costs, makes it harder to handle, and reduces workability. [Means for solving the problem]

[0009] In order to achieve the above-mentioned object, one embodiment of an underwater pump according to the present invention comprises a motor chamber accommodating a motor having a motor shaft, a pump chamber accommodating an impeller attached to the motor shaft, a shaft seal device provided between the motor chamber and the pump chamber and sealing the motor shaft, an oil chamber provided between the motor chamber and the pump chamber and for storing lubricating oil for the shaft seal device, a water submersion reservoir chamber having a plurality of leakage reservoirs arranged so that liquid leaking from the shaft seal device into the motor chamber side flows in sequentially and is stored therein, and a water submersion detector provided in each of the plurality of leakage reservoirs and detecting the liquid that has flowed in each of the plurality of leakage reservoirs.

[0010] An overflow wall may be interposed between the plurality of leakage reservoirs.

[0011] The flooded reservoir chamber may include an annular groove surrounding the motor shaft, and the plurality of leakage reservoirs may be provided in communication with the annular groove.

[0012] The submerged reservoir chamber can be divided by the overflow walls to form the plurality of leakage reservoirs.

[0013] A plurality of the overflow walls may be provided, and three or more of the leakage reservoirs may be provided.

[0014] The overflow walls may have different heights.

[0015] The plurality of leakage reservoirs may be spaced apart from one another and connected to one another by flow paths.

[0016] The plurality of leakage reservoirs may be arranged in series in a radial direction about the motor shaft.

[0017] The plurality of leakage reservoirs may be arranged consecutively in a circumferential direction around an axis of the motor shaft.

[0018] The submersible pump further includes a detection circuit that detects the detection signal of the water submersion detector, and the detection circuit may include a parallel circuit that connects each of the water submersion detectors in parallel, a resistor of known resistance value connected in series to each of the water submersion detectors within the parallel circuit, and a measurement unit arranged outside the submersible pump that measures the electrical characteristics at both ends of the parallel circuit.

[0019] The submersible pump further includes a detection circuit that detects the detection signal of the water submersion detector, and the detection circuit may include a parallel circuit that connects each of the water submersion detectors in parallel, a resistor of known resistance value connected in series to each water submersion detector other than the last water submersion detector in the parallel circuit, and a measurement unit arranged outside the submersible pump that measures the electrical characteristics at both ends of the parallel circuit.

[0020] The submersible pump may further include a detection prediction circuit that calculates an approximation function of the relationship between the operating time of the submersible pump and the volume of a leakage reservoir based on the time until each of the two or more submersion detectors detects flooding in its respective leakage reservoir and the known volume of each of the flooded leakage reservoirs, and calculates a predicted time until the next submersion detector detects flooding based on the approximation function.

[0021] The detection prediction circuit can calculate a predicted time at which the final stage water submersion detector will detect water submersion. Effect of the Invention

[0022] The present invention provides a water flooding chamber with multiple leakage reservoir sections that are connected together so that liquid that leaks from the shaft seal device into the motor chamber flows in succession and is stored therein, and by providing a water flooding detector in each liquid flooding chamber, the height dimension of the water flooding chamber can be reduced, and the height dimension of the underwater pump can be reduced.

[0023] Furthermore, according to the present invention, the detection prediction circuit having the above configuration can predict the time when the water submersion detector will make detection.

[0024] Furthermore, according to the present invention, the detection circuit having the above-described configuration allows the wiring of the water submersion detector to be used as a common wiring, thereby reducing the number of wires in the pump cable drawn from the submersible pump and making the pump cable thinner. [Brief description of the drawings]

[0025] [Figure 1] 1 is a front view showing a first embodiment of a submersible pump according to the present invention. [Diagram 2] FIG. 2 is a plan view of the submersible pump of FIG. 1. [Diagram 3] 4 is a longitudinal sectional view of the submersible pump of FIG. 1, and is an expanded longitudinal sectional view taken along line AA of FIG. [Figure 4] FIG. 2 is a cross-sectional view taken along line BB in FIG. [Diagram 5] FIG. 4 is a partially enlarged view of FIG. [Figure 6]8 is an enlarged vertical cross-sectional view of a submerged reservoir chamber, which is a component of the submersible pump of FIG. 1, taken along line AA of FIGS. 4 and 7. FIG. [Figure 7] FIG. 7 is a plan view of the submerged reservoir chamber of FIG. 6. [Figure 8] FIG. 7 is a perspective view of the submerged reservoir chamber of FIG. 6. [Figure 9] 9 is a perspective view of the submerged reservoir chamber of FIG. 8, seen from a different direction. [Figure 10] FIG. 4 is a central vertical cross-sectional view showing a second embodiment of a submersible pump according to the present invention. [Figure 11] 11 is a cross-sectional view of the submersible pump shown in FIG. 10 taken along line AA. [Figure 12] FIG. 11 is a partially enlarged vertical cross-sectional view of the submersible pump of FIG. 10. [Figure 13] FIG. 2 is a circuit diagram for detecting a submersion detection signal of the submersible pump according to the present invention. [Figure 14] FIG. 11 is a circuit diagram showing a submersion detection circuit of another embodiment of a submersible pump according to the present invention. [Figure 15] 1 is a graph plotting the relationship between the detection time of a water submersion detector for a submersible pump according to the present invention and the volume of a leakage reservoir in a water submersion reservoir. [Figure 16] 1 is a graph plotting the relationship between the detection time of a water submersion detector for a submersible pump according to the present invention and the volume of a leakage reservoir in a water submersion reservoir. [Figure 17] 19 is a partially enlarged longitudinal sectional view showing a modified embodiment of the submersible pump according to the present invention, which corresponds to the cross section taken along line BB in FIG. 18. FIG. [Figure 18] 18 is a cross-sectional view of the submersible pump shown in FIG. 17 taken along line AA. [Figure 19] 21 is a partially enlarged longitudinal sectional view showing a third embodiment of the submersible pump according to the present invention, which corresponds to the cross section taken along line BB in FIG. 20. [Figure 20] 20 is a cross-sectional view taken along line AA in FIG. 19. [Figure 21] FIG. 23 is a partially enlarged longitudinal sectional view showing a fourth embodiment of the submersible pump according to the present invention, which corresponds to the cross section taken along line BB in FIG. 22. [Figure 22]22 is a cross-sectional view taken along line AA in FIG. 21. [Figure 23] FIG. 25 is a partially enlarged longitudinal sectional view showing a fifth embodiment of the submersible pump according to the present invention, which corresponds to the cross section taken along line BB in FIG. 24. [Figure 24] 24 is a cross-sectional view taken along line AA in FIG. 23. [Diagram 25] FIG. 1 is a central vertical cross-sectional view showing a conventional submersible pump. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] BEST MODE FOR CARRYING OUT THE DISCLOSURE OF THE DISCLOSURE The present invention relates to a submersible pump and an embodiment thereof.

[0027] First, a submersible pump according to a first embodiment of the present invention will be described with reference to Figures 1 to 9. The submersible pump 1 according to the first embodiment of the present invention includes a motor chamber 3 accommodating a motor 2 having a motor shaft 2a, a pump chamber 5 accommodating an impeller 4 attached to the motor shaft 2a, a shaft seal device 6 provided between the motor chamber 3 and the pump chamber 5 to seal the motor shaft 2a, an oil chamber 7 provided between the motor chamber 3 and the pump chamber 5 to accommodate lubricating oil L for the shaft seal device 6, a water-filled reservoir chamber 8 having a plurality of leakage reservoirs 8a, 8b provided so that liquid leaking from the shaft seal device 6 to the motor chamber 3 side flows in and is stored therein, and water-filled detectors 9a, 9b for detecting the liquid that flows in each of the plurality of leakage reservoirs 8a, 8b.

[0028] The submersible pump 1 is a vertical submersible pump in which a motor shaft 2a is installed vertically. A rotor 2b is fixed to the motor shaft 2a, and a stator 2c is fixed inside a motor chamber 3.

[0029] Referring to Figure 3, the casing 10 of the submersible pump 1 is composed of multiple casing segments 10a, 10b, 10c, 10d, and 10e connected in the vertical direction. A strainer 11 is connected to the bottom of the submersible pump 1. The casing segment 10a houses the impeller 4. The casing segment 10b is provided with an oil chamber 7 surrounding the motor shaft 2a, and the oil chamber 7 houses a shaft seal device (mechanical seal) 6 and stores lubricating oil.

[0030] The oil chamber 7 of the casing segment 10b accommodates a submerged water chamber 8. The casing segment 10c supports and accommodates a bearing 16 that receives the motor shaft 2a. The oil chamber 7 of the casing segment 10b is closed by the casing segment 10c.

[0031] The flooded reservoir chamber 8 includes an annular groove 8c that fits into the upper portion of the shaft seal device 6 and surrounds the motor shaft 2a, and multiple leakage reservoirs 8a, 8b that communicate with the annular groove 8c. The inner periphery of the annular groove 8c fits into the upper portion of the shaft seal device 6 in a liquid-tight manner via a seal packing. The leakage reservoir 8a communicates with the annular groove 8c through an inlet 8a1 that opens into the bottom surface of the annular groove 8c. Meanwhile, the leakage reservoir 8b communicates with the annular groove 8c through an inlet 8b2 that is surrounded by an overflow wall 8b1 that rises from the bottom surface of the annular groove 8c.

[0032] The leakage reservoirs 8a, 8b are arranged apart from each other in the circumferential direction of the annular groove 8c, but they can also be connected to be integrally configured. In addition, although not shown, the overflow wall can be omitted by opening the inlet 8b2 to the outer peripheral wall 8c1 of the annular groove 8c and locating the inlet 8b2 at a higher position than the inlet 8a1.

[0033] By arranging the leakage reservoirs 8a, 8b side by side in this manner, two-stage detection is possible even if the water submersion detectors 9a, 9b are at the same height position, making it possible to reduce the height dimension of the submersible pump 1 compared to conventional methods.

[0034] When the shaft seal device 6 deteriorates, water seeps in from the pump chamber 5 to the oil chamber 7, and then from the oil chamber 7 to the motor chamber 3 along the motor shaft 2a. The liquid that seeps in along the motor shaft 2a flows into the annular groove 8c and into the leakage reservoir 8a. At the beginning of the inflow, the liquid that flows into the annular groove 8c does not flow into the leakage reservoir 8b because of the overflow wall 8b1. When the leakage reservoir 8a is filled with water and the level of the liquid flowing into the annular groove 8c exceeds the overflow wall 8b1, the liquid starts to flow into the leakage reservoir 8b.

[0035] In this way, liquid flows into the leakage reservoir 8b after the leakage reservoir 8b becomes full, so that the flooding detector 9b in the reactor liquid reservoir 8b detects flooding with a time lag after the flooding detector 9a in the leakage reservoir 8a detects flooding.

[0036] According to the submersible pump 1 configured as described above, by providing water flood detectors 9a, 9b in the leakage reservoirs 8a, 8b, into which liquid that has leaked from the shaft seal device 6 into the motor chamber 3 sequentially flows, it is possible to reduce the height dimension compared to the conventional case in which water flood detectors are provided above and below, and the submersible pump 1 can be made smaller.

[0037] Next, a submersible pump 1 according to a second embodiment of the present invention will be described with reference to FIGS. The underwater pump 1 of the second embodiment, like the first embodiment, comprises a motor chamber 3 accommodating a motor 2 having a motor shaft 2a, a pump chamber 5 accommodating an impeller 4 attached to the motor shaft 2a, a shaft sealing device 6 provided between the motor chamber 3 and the pump chamber 5 for sealing the motor shaft 2a, an oil chamber 7 provided between the motor chamber 3 and the pump chamber 5 for accommodating lubricating oil for the shaft sealing device 6, a water flooding chamber 8 having a number of leakage reservoirs 8a, 8b arranged so that liquid leaking from the shaft sealing device 6 to the motor chamber 3 side flows in and is stored in sequence, and water flooding detectors 9a, 9b for detecting the liquid that has flowed in each of the multiple leakage reservoirs 8a, 8b.

[0038] The casing 10 of the submersible pump 1 is composed of multiple casing segments 10a, 10b, 10c, 10d, and 10e connected in the vertical direction. A strainer 11 is connected to the bottom of the submersible pump 1. The casing segment 10a houses the impeller 4. The casing segment 10a and the casing segment 10b are separated by a plate 12. The casing segment 10b is provided with a shaft seal device (mechanical seal) 6 in an oil chamber 7 closed by a cover plate 13, in which lubricating oil is stored. The casing segment 10b is formed with a recess that forms a submerged reservoir chamber 8. The casing segment 10c supports and houses a bearing 16 that receives the motor shaft 2a, and the top and bottom of the bearing 16 are closed by cover plates 17 and 18.

[0039] Due to deterioration or the like of the shaft seal device 6, water floods from the pump chamber 5 into the oil chamber 7, and then from the oil chamber 7 to the motor chamber 3 along the motor shaft 2a. A gap is formed between the casing segment 10b and the cover plate 18, and liquid leaking from the shaft seal device 6 (a mixture of water in the pump chamber 5 and the lubricating oil in the oil chamber 7) flows into the water flooding chamber 8 from the oil chamber 7 to the motor chamber 3 through the gap.

[0040] The flooded reservoir chamber 8 has a doughnut shape surrounding the motor shaft 2a, is fitted liquid-tightly to the upper part of the shaft seal device 6 via a seal, and is divided into two leakage reservoirs 8a and 8b by a concentric overflow wall 8s centered on the motor shaft 2a. The multiple leakage reservoirs 8a and 8b are connected horizontally and radially centered on the motor shaft 2a. The bottom height positions of the leakage reservoirs 8a and 8b can be set to the same height position. The liquid that flows into the flooded reservoir chamber 8 flows into the leakage reservoir 8a on the side closer to the motor shaft 2a, i.e., the upstream side, and when the amount of flooding increases and the liquid level of the leakage reservoir 8a rises, it overflows the overflow wall 8s and flows into the leakage reservoir 8b on the side farther from the motor shaft 2a, i.e., the downstream side. Water flood detector 9a detects the intrusion of liquid into upstream leakage reservoir 8a, and then water flood detector 9b detects the intrusion of liquid into downstream leakage reservoir 8b. Water flood detectors 9a and 9b are preferably float switches, although other water flood detectors capable of detecting the inflow of liquid into water flood reservoir 8 may also be used.

[0041] Due to deterioration or the like of the shaft seal device 6, water floods from the pump chamber 5 into the oil chamber 7, and then from the oil chamber 7 to the motor chamber 3 along the motor shaft 2a. A gap is formed between the casing segment 10b and the cover plate 18, and liquid leaking from the shaft seal device 6 (a mixture of water in the pump chamber 5 and the lubricating oil in the oil chamber 7) flows into the water flooding chamber 8 from the oil chamber 7 to the motor chamber 3 through the gap.

[0042] By detecting flooding in two stages using water flood detectors 9a, 9b provided in horizontally connected leakage reservoirs 8a, 8b as in the second embodiment described above, it is possible to reduce the height dimension compared to the conventional case in which water flood detectors are provided above and below, and the submersible pump 1 can be made smaller.

[0043] FIG. 13 shows a circuit diagram showing the detection circuit 19 of the water submersion detectors 9a, 9b in the first and second embodiments. Float switches are used as the water submersion detectors 9a, 9b. The water submersion detectors 9a, 9b are connected in parallel, and a resistor R1 with a known resistance value is connected in series to the water submersion detector 9a in the front stage (upstream side) close to the motor shaft 2a, and no resistor is connected to the water submersion detector 9b in the rear stage. A measuring unit 19b is provided to measure the electrical characteristics of both ends of the parallel circuit 19a in which the water submersion detectors 9a, 9b are connected in parallel. The measuring unit 19b is provided in a control panel 24 installed outside the submersible pump 1.

[0044] The measurement unit 19b may include, for example, a constant current circuit that passes a constant current through the detection circuit 19, and a resistance measurement circuit that measures the resistance value between both ends of the parallel circuit 19a. Since the resistance value between both ends of the parallel circuit 19a measured by the measurement unit 19b differs between when the float switch of the water flood detector 9a is on and when the float switches of both water flood detectors 9a, 9b are on, the on / off state of the float switches of the water flood detectors 9a, 9b can be determined from the resistance value. When the resistance value of the known resistor R1 is r, when the water flood detector 9a is on, the resistance value between both ends of the parallel circuit 19a is r, and when both water flood detectors 9a, 9b are on, the resistance value between both ends of the parallel circuit 19a is close to zero.

[0045] When the water submersion detector 9b detects water submersion and turns on after the water submersion detector 9a, the control unit 20 receives an ON signal (resistance value close to zero) from the measurement unit 19b, and the control unit 20, which controls the drive current of the submersible pump 1, turns off the magnet switch 21, cuts off the power supply to the submersible pump 1, and stops the submersible pump 1. In order to reliably pick up the signal that the water submersion detector 9b in the last stage (the most downstream side) is turned on, it is preferable that the resistance value between both ends of the parallel circuit 19a indicates a value close to zero, which maximizes the difference in the detected resistance value between when only the water submersion detector 9a is on and when both the water submersion detectors 9a and 9b are on, thereby increasing the detection accuracy. Of course, it is also possible to connect known resistances in series to all the water submersion detectors connected in parallel. The measurement unit 19b, which measures the electrical characteristics between both ends of the parallel circuit 19a, may be equipped with a voltage measurement circuit or a current measurement circuit instead of a resistance measurement circuit.

[0046] By using a detection circuit 19 including a parallel circuit 19a as shown in Figure 13, there is no need to pull the wiring for each of the water immersion detectors 9a, 9b from the casing 10 of the submersible pump 1, and it is sufficient to pull two common wires 19c, 19d at both ends of the parallel circuit 19a from the submersible pump 1, so that the pump cable 22 (Figures 1 and 10) can be made thinner. Making the pump cable 22 thinner makes it easier to handle the pump cable 22 and also reduces costs.

[0047] In the above first and second embodiments, examples have been shown in which the water flooding reservoir chamber 8 is provided with two liquid leakage reservoirs 8a, 8b, but three or more liquid leakage reservoirs can also be provided. As a modification of the second embodiment, two overflow walls can be provided concentrically to partition the reservoir into three or more liquid leakage reservoirs. When three or more liquid leakage reservoirs are provided, a water flood detector is provided in each liquid leakage reservoir, and the respective water flood detectors are connected in parallel.

[0048] For example, as shown in FIG. 14, when the leakage reservoirs 8a, 8b, and 8c are divided by overflow walls 8s and 8t, water ingress detectors 9a, 9b, and 9c are provided in the leakage reservoirs 8, 8b, and 8c, respectively. The water ingress detectors 9a, 9b, and 9c are connected in parallel, and resistors R1 and R2 with known resistance values ​​r are connected in series to the water ingress detectors 9a and 9b of the leakage reservoirs 8a and 8b closer to the motor shaft 2a, respectively, and no resistance is connected to the water ingress detector 9c in the last stage (most downstream side). The detection circuit 19 detects the resistance value between both ends of the parallel circuit 19a. The measurement unit 19b measures the resistance value r when only the water ingress detector 9a is turned on, measures the resistance value 1 / 2r when the water ingress detectors 9a and 9b are turned on, and measures a resistance value close to zero when all the water ingress detectors 9a, 9b, and 9c are turned on. When the final water flood detector 9c turns on (detects water flooding), the control unit 20 receives an on signal (resistance value close to zero) from the measurement unit 19b, and the control unit 20 turns off the magnetic switch 21, cutting off the power supply to the submersible pump 1 and stopping the submersible pump 1. It is also possible to connect known resistors in series to all of the water flood detectors connected in parallel.

[0049] The graphs in Figures 15 and 16 show the relationship between the volume v (horizontal axis) of the liquid leakage reservoirs 8a, 8b, 8c and the operating time (vertical axis) of the water flooding detectors 9a, 9b, 9c when three stages of water flooding detectors 9a, 9b, 9c are provided. The known volumes va, vb, vc of the liquid leakage reservoirs 8a, 8b, 8c are all 200cc. The known volumes are the volumes at the time of detection by the water flooding detectors. The operating time from when the submersible pump 1 starts operating to when water flooding is detected by the two upstream water flooding detectors 9a, 9b is plotted on the time axis (vertical axis).

[0050] Using the times ta, tb until the two upstream flood detectors 9a, 9b detect flooding in the respective leak reservoirs 8a, 8b and the known volumes va, vb of the flooded leak reservoirs 8a, 8b, the relationship between the operating time t of the submersible pump and the volume v of the leak reservoir can be expressed as an approximate function t = f(v). The least squares method, for example, can be used to calculate the approximate function. The predicted time tc until the next flood detector detects flooding can be calculated based on the approximate function t = f(v).

[0051] In the graph of Figure 15, the time ta from when the submersible pump 1 starts operating until the topmost (most upstream) water flooding detector 9a detects water flooding is 1000 hours, and the time tb from when the submersible pump 1 starts operating until the next water flooding detector 9b detects water flooding is 1200 hours. In Figure 15, the predicted time until detection by the last water flooding detector 9c is 1250 hours.

[0052] In the graph of Figure 16, the time ta from when the submersible pump 1 starts operating until the topmost (most upstream) water flooding detector 9a detects water flooding is 300 hours, and the time tb from when the submersible pump 1 starts operating until the next water flooding detector 9b detects water flooding is 1000 hours. In Figure 16, the predicted time until the last water flooding detector 9c detects water flooding is 2000 hours.

[0053] The calculation of the predicted time tc is performed in the detection prediction circuit 23. The detection prediction circuit 23 may include a computer, a storage device, a clock generation circuit, a counter circuit, etc., and may receive a signal from the measurement unit 19b, calculate the times ta and tb in the counter circuit using a clock from the clock generation circuit, store the times ta and tb and the volumes va, vb, and vc of the leakage reservoir, and an approximation calculation program in the storage device, calculate an approximation function t=f(v) in a calculation device in the computer, and output the predicted detection time of the final stage water inundation detector 9c calculated using the approximation function. The predicted detection time may be output to, for example, a monitor. The detection prediction circuit 23 may be mounted in the control panel of the submersible pump 1, but may also be mounted in another location.

[0054] When there are three or more water submersion detectors, it is possible to predict the timing of maintenance of the submersible pump 1 by calculating the predicted time when the last water submersion detector will detect water submersion.

[0055] Furthermore, the shape of the flood water chamber 8 is not particularly limited as long as it is configured so that the liquid leaking from the shaft seal device 6 to the motor chamber 3 side flows in and is stored sequentially at time intervals. For example, as a modification of the flood water chamber having a circular shape in plan view in the second embodiment, as shown in Figures 17 and 18, the flood water chamber 8 may have a sector shape in plan view (the shape in Figure 18) and the overflow wall 8s may have a concentric arc shape.

[0056] 19 and 20 show a submersible pump 1 according to a third embodiment of the present invention. The submersible pump 1 of the third embodiment differs from the first and second embodiments in the form of the submerged reservoir chamber 8. The submerged reservoir chamber 8 of the third embodiment includes a leakage reservoir section 8a communicating with the shaft seal device 6, and a leakage reservoir section 8b connected to the leakage reservoir section 8 via an overflow wall 8s so as to be aligned in the circumferential direction around the axis of the motor shaft 2a, and a water flood detector 9a, 9b is provided in each of the leakage reservoir sections 8a, 8b. In the third embodiment, two leakage reservoir sections 8a, 8b are provided, but three or more leakage reservoir sections may be connected in the circumferential direction of the motor shaft 2a via an overflow wall, and a water flood detector may be provided in each leakage reservoir section. The leakage reservoir sections 8a, 8b are connected to each other in the horizontal direction, and the height of the bottom surface of each of them may be set to the same height.

[0057] 21 and 22 show a submersible pump 1 according to a fourth embodiment of the present invention. The submersible pump 1 of the fourth embodiment is a modification of the third embodiment, and differs from the second embodiment in that the leakage reservoirs 8a, 8b are connected by a pipe-shaped or groove-shaped flow path 8p, rather than an overflow wall, and are connected in series in the circumferential direction around the axis of the motor shaft 2a. In the fourth embodiment, two leakage reservoirs 8a, 8b are provided, but it is also possible to connect three or more leakage reservoirs in the circumferential direction of the motor shaft 2a via the flow path 8p, and provide a water intrusion detector in each leakage reservoir.

[0058] 23 and 24 show a submersible pump 1 according to a fifth embodiment of the present invention. The submerged reservoir chamber 8 of the fifth embodiment is a hybrid type of the third and fourth embodiments. The submerged reservoir chamber 8 of the fifth embodiment has a sector shape in a plan view, and is divided into three leakage reservoir chambers 8a, 8b, and 8c by an overflow wall 8s in a concentric arc shape centered on the motor shaft 2a and an overflow wall 8u in an L-shape in a plan view. Water intrusion detectors 9a, 9b, and 9c are disposed in the respective leakage reservoir chambers 8a, 8b, and 8c. The height of the overflow wall 8s is set lower than the height of the overflow wall 8u. Therefore, the liquid leaking from the shaft seal device 6 overflows the overflow walls 8s and 8u in the order of the leakage reservoir chamber 8a, the leakage reservoir chamber 8b, and the leakage reservoir chamber 8c, and is stored therein.

[0059] The present invention should not be construed as being limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the present invention. [Explanation of symbols]

[0060] 1. Submersible pump 2a Motor shaft 2 Motors 3. Motor Room 4 Impeller 5. Pump Room 6 Shaft sealing device 7 Oil chamber 8 Flooding chamber 8a, 8b, 8c Leakage reservoir 8s, 8t, 8u overflow wall 8p flow channel 9a, 9b Water ingress detector 19 Detection circuit 19a parallel circuit 23 Detection and prediction circuit

Claims

1. A vertical submersible pump in which a motor shaft is installed in a vertical direction, a motor chamber in which a motor having the motor shaft is accommodated; a pump chamber that houses an impeller attached to the motor shaft; a shaft seal device provided between the motor chamber and the pump chamber and configured to seal the motor shaft; an oil chamber disposed between the motor chamber and the pump chamber and configured to accommodate the shaft seal device and lubricating oil; a water submersion reservoir having a plurality of leakage reservoirs arranged so that the liquid leaking from the shaft seal device to the motor chamber side sequentially flows in and is stored therein; a water ingress detector provided in each of the plurality of liquid leakage reservoirs and configured to detect liquid that has flowed into each of the plurality of liquid leakage reservoirs; Equipped with the submerged reservoir chamber includes an annular groove portion that is fitted into an upper portion of the shaft seal device and surrounds the motor shaft, The plurality of leakage reservoirs are each provided in communication with the annular groove portion via an inlet provided in the annular groove portion, and are arranged side by side.

3. The vertical submersible pump.

2. An overflow wall is interposed between the plurality of leakage reservoirs, The vertical submersible pump according to claim 1 , wherein the overflow wall is formed so as to protrude from a bottom surface of the annular groove and surround the inlet.

3. A vertical submersible pump as described in claim 1 or 2, wherein the water ingress detectors provided in each of the multiple leakage reservoirs are arranged at the same height as each other.

4. A vertical submersible pump in which a motor shaft is installed in a vertical direction, a motor chamber in which a motor having the motor shaft is accommodated; a pump chamber that houses an impeller attached to the motor shaft; a shaft seal device provided between the motor chamber and the pump chamber and configured to seal the motor shaft; an oil chamber disposed between the motor chamber and the pump chamber and configured to accommodate the shaft seal device and lubricating oil; a water submersion reservoir having a plurality of leakage reservoirs arranged so that the liquid leaking from the shaft seal device to the motor chamber side sequentially flows in and is stored therein; a water ingress detector provided in each of the plurality of liquid leakage reservoirs and configured to detect liquid that has flowed into each of the plurality of liquid leakage reservoirs; Equipped with the submerged reservoir chamber has a donut-shaped recess surrounding the motor shaft, and is fitted to an upper portion of the shaft seal device; the plurality of leakage reservoirs are partitioned by overflow walls provided in the recess, and the respective leakage reservoirs are connected in a horizontal direction; 3. The vertical submersible pump.

5. The vertical submersible pump according to claim 4 , wherein a plurality of the overflow walls are provided, and the vertical submersible pump has three or more of the leakage reservoirs.

6. The vertical submersible pump according to claim 5 , wherein the overflow walls have different heights.

7. The vertical submersible pump according to claim 1 or 4, wherein the plurality of leakage reservoirs are spaced apart from one another and connected to one another by flow paths.

8. The vertical submersible pump according to claim 4 , wherein the plurality of leakage reservoirs are arranged in series in a radial direction about the motor shaft.

9. The vertical submersible pump according to claim 1 or 4, wherein the plurality of leakage reservoirs are arranged in series in a circumferential direction around an axis of the motor shaft.

10. A detection circuit for detecting a detection signal from the water immersion detector is further provided. The detection circuit includes a parallel circuit that connects each of the water submersion detectors in parallel, a resistor of a known resistance value that is connected in series to each of the water submersion detectors in the parallel circuit, and a measurement unit that is disposed outside the submersible pump and measures electrical characteristics at both ends of the parallel circuit.

5. A vertical submersible pump according to claim 1 or 4.

11. A detection circuit for detecting a detection signal from the water immersion detector is further provided. The detection circuit includes a parallel circuit that connects each of the water submersion detectors in parallel, a resistor of a known resistance value that is connected in series to each of the water submersion detectors except for the final water submersion detector in the parallel circuit, and a measurement unit that is disposed outside the underwater pump and measures electrical characteristics at both ends of the parallel circuit.

5. A vertical submersible pump according to claim 1 or 4.

12. The vertical submersible pump of claim 1 or 4, further comprising a detection prediction circuit that calculates an approximation function of the relationship between the operating time of the submersible pump and the volume of a leakage reservoir from the time until each of the two or more submersion detectors detects submersion in its respective leakage reservoir and the known volume of each of the flooded leakage reservoirs, and calculates a predicted time until the next submersion detector detects submersion based on the approximation function.

13. The vertical submersible pump according to claim 12 , wherein the detection prediction circuit calculates a predicted time at which the final stage submersion detector will detect submersion.

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