Waterfall detection device, waterfall detection method, and drainage system

Abstract

To provide a device and a method of detecting fall of water from an operating pump more accurately, and to provide a draining system including such the device of detecting fall of water.SOLUTION: A draining system includes: a pump with an impeller; a drive source for rotatably driving the impeller of the pump; a thermometer for measuring a temperature of an exhaust gas discharged from the drive source; and a detector for fall of water that detects fall of water on the basis of a rate of increase in temperature of the exhaust gas per unit time.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a drainage system, a water-drop detection device, and a water-drop detection method, and particularly to a drainage system having a water-drop detection function for detecting that liquid has dropped from a pump during operation.

Background Art

[0002] Even during steady operation, water-drop may occur in a pump due to certain causes. When water-drop occurs, there is a risk that the impeller rotates idly and the underwater bearing is damaged. In view of such a situation, a device for detecting water-drop in an operating pump has been developed.

[0003] For example, Patent Document 1 discloses a pump device. According to this technology, it is possible to detect whether there is liquid in the pump during steady operation.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

[0007] The water drop detection unit may detect water drop based on the rate of increase in the exhaust gas temperature per unit time until a predetermined time has elapsed after the rotation speed of the impeller reaches a specified speed, and after the predetermined time has elapsed after the rotation speed of the impeller reaches a specified speed, it may detect water drop based on the temperature of the exhaust gas.

[0008] The water drop detection unit may detect water drop based on a comparison between the rate of increase in the exhaust gas temperature per unit time and a first specified value until a predetermined time has elapsed after the rotation speed of the impeller reaches a specified speed, and after the predetermined time has elapsed after the rotation speed of the impeller reaches a specified speed, it may detect water drop based on a comparison between the exhaust gas temperature and a second specified value.

[0009] The water drop detection unit may perform water drop detection based on the rate of increase per unit time of the exhaust gas temperature when the rotation speed of the impeller reaches a specified speed.

[0010] According to another aspect of the present invention, a drainage system is provided comprising: a pump having an impeller; a drive source for rotating the impeller of the pump; a thermometer for measuring the temperature of exhaust gas discharged from the drive source; and a water drop detection unit for detecting water drop based on the temperature of the exhaust gas after a predetermined time has elapsed since the rotation speed of the impeller reached a specified speed.

[0011] The water drop detection unit may measure time based on the point in time when the rotation speed of the impeller reaches a specified speed, and after the predetermined time has elapsed, detect water drop based on the temperature of the exhaust gas.

[0012] The system may also suppress false detections due to a delay in the rise of the exhaust gas temperature by detecting water falling based on the temperature of the exhaust gas after a predetermined time has elapsed since the rotation speed of the impeller reached a specified speed. [Effects of the Invention]

[0013] According to the drainage system, control device for the drainage system, and control method for the drainage system of the present invention, it is possible to detect water leaking from inside the pump during operation and to prevent false detection of water leaks. [Brief explanation of the drawing]

[0014] [Figure 1] A diagram showing the schematic configuration of a drainage system in an embodiment of the present invention. [Figure 2] A graph schematically illustrating how exhaust gas temperature rises. [Figure 3] A flowchart illustrating an example of a procedure for detecting water leakage based on the rate of increase in exhaust gas temperature per unit time. [Figure 4] A flowchart illustrating an example of a procedure for detecting water leakage based on exhaust gas temperature. [Figure 5] A flowchart illustrating an example of a procedure for detecting water leakage based on exhaust gas temperature and its rate of increase per unit time. [Modes for carrying out the invention]

[0015] Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.

[0016] (First Embodiment) Figure 1 is a diagram showing the schematic configuration of the drainage system 1 in an embodiment of the present invention.

[0017] The drainage system 1 includes a pump 10 that transfers liquid from a suction tank 11 to a discharge tank 18, a suction pipe 13 that connects the pump 10 to the suction tank 11, a discharge pipe 15 that connects the pump 10 to the discharge tank 18, and a prime mover 5 that serves as a drive source to drive the pump 10.

[0018] The pump 10 includes an impeller (not shown) housed in the pump 10. The impeller is connected to the speed reducer 6 via a rotating shaft, and the speed reducer 6 is connected to the prime mover 5. This pump 10 is a so-called horizontal shaft pump in which the rotating shaft extends in the horizontal direction. When the prime mover 5 rotationally drives the impeller, exhaust gas is discharged from the internal combustion engine of the prime mover 5. The exhaust gas is released into the atmosphere from an exhaust gas pipe 5a connected to the prime mover 5. The higher the load on the prime mover 5, the higher the temperature of the exhaust gas.

[0019] The suction pipe 13 extends vertically, and its suction port 12 is located in the liquid in the suction water tank 11. The pump 10 is disposed above the liquid level position in the suction water tank 11 and is installed on an installation floor 20 constituting the upper part of the suction water tank 11 via a pedestal 21. The downstream portion of the suction pipe 13 is a bent pipe portion, whereby the suction pipe 13 and the pump 10 are smoothly connected.

[0020] The discharge pipe 15 has a discharge port 16 that opens in the discharge water tank 18. This discharge port 16 is located at a position lower than the pump 10 and higher than the suction port 12. A flap valve 17 for preventing the backflow of the liquid transferred to the discharge water tank 18 is provided at the discharge port 16.

[0021] As can be seen from FIG. 1, the suction pipe 13, the pump 10, and the discharge pipe 15 as a whole form a siphon-type passage. A full water detector 30 having an electrode rod inside is provided above the pump 10, and this full water detector 30 detects whether the inside of the pump 10 is filled with liquid. Further, the inside of the pump 10 communicates with a vacuum pump 31 via the full water detector 30.

[0022] In such a configuration, when starting the drainage system 1, first, after fully closing the discharge valve 14, the inside of the pump 10 is evacuated by the vacuum pump 31 to form a negative pressure, and the liquid level position in the suction pipe 13 is raised. When the full water detector 30 detects that the inside of the pump 10 is filled with liquid, the prime mover 5 causes the impeller to rotate and the discharge valve 14 to open, whereby the liquid is transferred from the suction water tank 11 to the discharge water tank 18.

[0023] As described above, the pump 10 is located at a higher position than the liquid level in the suction tank 11. Therefore, if water falls during operation of the drainage system 1, the pump 10 may become unable to drain water or may be damaged. In this embodiment, water falls are detected by the water fall detection unit 2.

[0024] In detail, the drainage system 1 includes a thermometer 3, a speedometer 4, and a water drop detection unit 2. The thermometer 3 and the water drop detection unit 2 constitute a water drop detection device.

[0025] The thermometer 3 is installed, for example, inside the exhaust gas pipe 5a and measures the temperature of the exhaust gas discharged from the prime mover 5. The measured exhaust gas temperature is notified to the water fall detection unit 2. The speedometer 4 measures the rotational speed of the prime mover 5. Since the rotational speed of the impeller is the rotational speed of the prime mover 5 reduced by a predetermined ratio by the reduction gear 6, it can also be said that the speedometer 4 measures the rotational speed of the impeller. The measured rotational speed is notified to the water fall detection unit 2.

[0026] As shown in Figure 1, the water drop detection unit 2 is connected to the thermometer 3 and the speedometer 4. The water drop detection unit 2 detects water drop based on the acquired exhaust gas temperature and, if necessary, also takes into account the rotation speed of the prime mover 5 (impeller). If the water drop detection unit 2 determines that water drop has occurred, it may issue a command to the discharge valve 14 to close the discharge valve 14, stop the prime mover 5 to stop the operation of the drainage system 1, or issue an alarm.

[0027] Figure 2 is a schematic graph illustrating the rise in exhaust gas temperature as described above.

[0028] As shown in Figure 2, during normal operation as indicated by curve C1, i.e., when no water leakage occurs, water is drawn into the pump 10 when the pump 10 is started, increasing the load on the prime mover 5. Consequently, the exhaust gas temperature rises to approximately 450 degrees. As shown by curve C2, when the prime mover 5 is started while cold, the initial temperature of the exhaust gas is low, so it takes time, but eventually the exhaust gas temperature rises to approximately 450 degrees.

[0029] On the other hand, when water falls, as shown by curve C3, water is not drawn into the pump 10, so the load on the prime mover 5 does not increase significantly. Therefore, the exhaust gas temperature only rises to about 150 degrees Celsius.

[0030] Therefore, it is conceivable to detect water spillage based on the exhaust gas temperature when the impeller rotation speed reaches a specified speed. For example, it is conceivable to determine that water spillage has occurred when the exhaust gas temperature falls below a specified temperature (for example, 200 degrees in Figure 2).

[0031] However, if the prime mover 5 is started while cold, the rate at which the exhaust gas temperature rises is slow. For example, even if the impeller rotation speed reaches the specified speed at time T1 in Figure 2, the exhaust gas temperature may not have risen to the specified temperature. In such a case, there is a risk of false detection of water falling even if no water has actually fallen.

[0032] Therefore, in this embodiment, water drop detection is performed based on the rate of increase in exhaust gas temperature per unit time. As shown in Figure 2, during normal operation, especially during a predetermined period from the start of the pump 10, the rate of increase in exhaust gas temperature per unit time (ΔT / dt) is a relatively large value, regardless of whether the prime mover 5 is cold at the time of start-up or not. On the other hand, during water drop, even during the same predetermined period, the rate of increase in exhaust gas temperature per unit time (ΔT / dt) is not such a large value. No.

[0033] In other words, the rate of increase in exhaust gas temperature per unit time (ΔT / dt) during normal operation is, This is greater than the rate of increase in exhaust gas temperature per unit time (ΔT / dt) when using water. This property is then used to detect water leakage. The unit time can be set arbitrarily, but for example, it can be set to about 5 seconds. The specified value for the rate of increase in exhaust gas temperature per unit time, which is the criterion for determining water leakage, should preferably be set to a value that clearly indicates water leakage.

[0034] Figure 3 is a flowchart illustrating the detection of water leakage based on the rate of increase in exhaust gas temperature per unit time, as described above.

[0035] First, the prime mover 5 starts (step S1). Then, when the rotational speed measured by the speedometer 4 reaches the specified speed (YES in step S2), the water drop detection unit 2 detects that the rate of increase of the exhaust gas temperature per unit time (ΔT / dt) is less than the specified value (ΔT0 / dt). If this occurs (YES in step S3), it is determined that the vehicle has fallen into the water (step S4), and the rate of ascent (ΔT / d If t) is greater than or equal to the specified value (ΔT0 / dt) (NO in step S3), it is determined that there is no water leakage. Do it (Step S5).

[0036] Thus, in the first embodiment, water leakage is detected based on the rate of increase in exhaust gas temperature. Therefore, even when the pump 10 is started while the prime mover 5 is cold, water leakage can be detected with high accuracy.

[0037] (Second Embodiment) The first embodiment described above is particularly effective because, within a predetermined period from the start of the prime mover 5, the rate of increase of the exhaust gas temperature per unit time differs significantly between normal operation and when the water has fallen. However, as shown in Figure 2, after a certain amount of time has elapsed since the start of the prime mover 5, the difference in the rate of increase of the exhaust gas temperature per unit time between normal operation and when the water has fallen becomes smaller (in both cases, the exhaust gas temperature hardly rises at all), and water fall detection based on the rate of increase may become difficult.

[0038] On the other hand, as shown in Figure 2, once sufficient time has elapsed (for example, time T2 in Figure 2, about 60 seconds), even if the pump 10 is started with the prime mover 5 cooled down, the exhaust gas temperature will be high during normal operation, and low when the water is being drained. The second embodiment focuses on this point.

[0039] Figure 4 is a flowchart illustrating the detection of water leakage based on the exhaust gas temperature described above.

[0040] First, the prime mover 5 starts (step S11). Then, when the rotational speed measured by the speedometer 4 reaches the specified speed (YES in step S12), the water drop detection unit 2 starts timing based on that point in time (step S13). The water drop detection unit 2 determines that water has fallen in if the exhaust gas temperature is below the specified temperature (YES in step S15) at or after a specified time has elapsed since the rotational speed reached the specified speed (YES in step S14), or determines that there has been water drop (step S16), and determines that there has been no water drop if the exhaust gas temperature is above the specified temperature (NO in step S15).

[0041] Thus, in the second embodiment, water leakage is detected based on the exhaust gas temperature after a specified time has elapsed since the rotational speed reached a specified speed. In other words, water leakage detection based on the exhaust gas temperature is not performed until a specified time has elapsed since the rotational speed reached a specified speed. Therefore, even if the pump 10 is started when the prime mover 5 is cold, false detections due to the delayed rise in exhaust gas temperature can be suppressed, and water leakage can be detected with high accuracy.

[0042] (Third embodiment) In the second embodiment described above, the water drop detection based on exhaust gas temperature is performed after a specified time has elapsed since the rotation speed reached a specified speed, and water drop detection is not performed until the specified time has elapsed.

[0043] Therefore, the third embodiment described below combines the first embodiment with the second embodiment described above, enabling water fall detection both before and after the specified time has elapsed.

[0044] Figure 5 is a flowchart illustrating the detection of water leakage based on the exhaust gas temperature and its rate of increase per unit time.

[0045] First, the prime mover 5 starts (step S21). Then, when the rotational speed measured by the speedometer 4 reaches the specified speed (YES in step S22), the water fall detection unit 2 starts timing based on that point in time (step S23).

[0046] Until a specified time has elapsed after the rotational speed reaches a specified speed (NO in step S24), the water drop detection unit 2 detects water drop based on the rate of increase in exhaust gas temperature per unit time, as described in the first embodiment. That is, the water drop detection unit 2 detects water drop if the rate of increase in exhaust gas temperature per unit time (ΔT / dt) is less than a specified value (ΔT0 / dt) (step S25 If the answer is YES, it is determined that the vehicle has fallen into the water (step S26), and the rate of ascent (ΔT / dt) is equal to the specified value (ΔT0 If the value is greater than or equal to / dt (NO in step S25), it is determined that there is no water leakage (step S27), and the determination is repeated until the specified time has elapsed.

[0047] After a specified time has elapsed since the rotation speed reached the specified speed (YES in step S24), the water drop detection unit 2 detects water drop based on the exhaust gas temperature, as described in the second embodiment. That is, if the exhaust gas temperature is below the specified temperature (YES in step S28), the water drop detection unit 2 determines that water has dropped (step S29), and if the exhaust gas temperature is above the specified temperature (NO in step S28), it determines that there is no water drop (step S30).

[0048] Thus, in the third embodiment, water drop is detected based on the rate of increase in exhaust gas temperature per unit time until a specified time has elapsed after the rotational speed reaches a specified speed, and after the specified time has elapsed, water drop is detected based on the exhaust gas temperature. Therefore, even if the pump 10 is started when the prime mover 5 is cold, water drop can be detected before the exhaust gas temperature rises, while suppressing false detections due to the delayed rise in exhaust gas temperature.

[0049] In addition, in step S2 of Figure 3, step S12 of Figure 4, and step S22 of Figure 5, the next step may be initiated based on a predetermined amount of time elapsed since the start of the prime mover 5, rather than the rotational speed reaching a specified speed.

[0050] The embodiments described above are intended to enable persons with ordinary skill in the art to implement the present invention. Various modifications of the above embodiments can be made naturally by those skilled in the art, and the technical idea of ​​the present invention can be applied to other embodiments as well. Therefore, the present invention is not limited to the embodiments described, but should be in the broadest scope according to the technical idea defined by the claims. [Explanation of Symbols]

[0051] 1. Drainage system 2. Waterfall detection unit 3 thermometer 4 speedometer 5. Engine 6 Reducer 10 pumps 11. Suction tank 12 Inlet 13 Suction pipe 14 Discharge valve 15 Discharge pipe 16 Outlet 17 Flap valve 18 Discharge tank 20 Installation floor 21. Stand 30. Water level detector 31 Vacuum pump

Claims

1. A pump having an impeller, A drive source that rotates the impeller of the aforementioned pump, A thermometer for measuring the temperature of exhaust gas discharged from the aforementioned drive source, A drainage system comprising: a drainage detection unit that determines that water has fallen if the rate of increase in the temperature of the exhaust gas per unit time is less than a specified value until a predetermined time has elapsed after the rotation speed of the impeller reaches a specified speed, and detects water falling based on the temperature of the exhaust gas after the predetermined time has elapsed after the rotation speed of the impeller reaches a specified speed.

2. The aforementioned water drop detection unit is From the time the rotational speed of the impeller reaches a specified speed until a predetermined time has elapsed, water leakage is detected based on a comparison between the rate of increase in the temperature of the exhaust gas per unit time and a first specified value. The drainage system according to claim 1, wherein, after the rotational speed of the impeller reaches a specified speed and a predetermined time has elapsed, water is detected to fall based on a comparison between the temperature of the exhaust gas and a second specified value.

3. The drainage system according to claim 1 or 2, wherein the water drop detection unit performs water drop detection based on the rate of increase per unit time of the exhaust gas temperature when the rotation speed of the impeller reaches a specified speed.

4. A thermometer that measures the temperature of exhaust gas discharged from the drive source that rotates the pump impeller, A water drop detection device comprising: a water drop detection unit that determines water drop if the rate of increase in the temperature of the exhaust gas per unit time is less than a specified value until a predetermined time has elapsed after the rotation speed of the impeller reaches a specified speed; and a water drop detection unit that detects water drop based on the temperature of the exhaust gas after the predetermined time has elapsed after the rotation speed of the impeller reaches a specified speed.

5. A process for measuring the temperature of exhaust gas discharged from a drive source that rotates the impeller of a pump, A method for detecting water leakage, comprising the steps of: determining water leakage if the rate of increase in the temperature of the exhaust gas per unit time is less than a specified value until a predetermined time has elapsed after the rotation speed of the impeller reaches a specified speed; and detecting water leakage based on the temperature of the exhaust gas after the predetermined time has elapsed after the rotation speed of the impeller reaches a specified speed.

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