Submersible pump device

Abstract

To perform liquid level control with high accuracy while realizing space saving.SOLUTION: A submerged pump device comprises a pump, a liquid level gauge, and a control unit. The pump is provided in a housing. The liquid level gauge is arranged at the bottom part of the housing, and measures a liquid level using a semiconductor pressure sensor. The control unit controls the pump to start or stop depending on the liquid level measured by the liquid level gauge.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an underwater pump device for draining liquid.

Background Art

[0002] For underwater pump devices used for draining wastewater such as domestic sewage, there is a known technique for detecting the water level by a float switch or a submersible level gauge and controlling the start and stop of the pump (see, for example, Patent Document 1 and Patent Document 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the float switch according to Patent Document 1 and the submersible level gauge according to Patent Document 2 are separate from the pump device and are also of a certain size, so there is a problem that space for the float switch or the submersible level gauge must be secured. An object of the present invention is to achieve space saving while performing highly accurate liquid level control.

Means for Solving the Problems

[0005] According to one aspect of the present invention, an underwater pump device includes a pump, a liquid level gauge, and a control unit. The pump is provided in a housing. The liquid level gauge is disposed at the lower part of the housing and measures the liquid level of the liquid using a semiconductor pressure sensor. The control unit controls the pump to start or stop according to the liquid level measured by the liquid level gauge.

Effects of the Invention

[0006] According to the present invention, it is possible to achieve high-precision liquid level control while saving space. [Brief explanation of the drawing]

[0007] [Figure 1] A diagram showing a submersible pump device according to this embodiment. [Figure 2] This figure shows another example of a submersible pump device according to this embodiment. [Figure 3] A flowchart showing an example of the operation of the submersible pump device according to this embodiment. [Figure 4] A diagram showing an example configuration of a submersible pump system with multiple submersible pump units. [Figure 5] A sequence diagram showing an example of alternating operation of the submersible pump system according to this embodiment. [Figure 6] A sequence diagram showing an example of alternating parallel operation of the submersible pump system according to this embodiment. [Figure 7] A sequence diagram showing an example of alternating parallel operation of the submersible pump system according to this embodiment. [Modes for carrying out the invention]

[0008] The submersible pump device and submersible pump system according to the embodiment will be described below with reference to the drawings. In the following, elements that are the same or similar as those already described will be denoted by the same or similar reference numerals, and redundant explanations will be omitted in principle. For example, when there are multiple identical or similar elements, a common reference numeral may be used to describe each element without distinction, or an alphabet or sub-number may be used in addition to the common reference numeral to describe each element separately.

[0009] Figure 1 is an explanatory diagram showing the configuration of a submersible pump according to one embodiment of the present invention. The submersible pump device 10 is configured to be able to pump water stored in the water storage tank 100 toward the external piping 200.

[0010] Liquids such as water, wastewater, and sewage flow into the water storage tank 100 from the outside. The set liquid level L0 is the stop liquid level at which the submersible pump device 10 stops. The set liquid level L1 is a liquid level higher than the set liquid level L0 and is the starting liquid level at which the pump of the submersible pump device 10 starts.

[0011] The submersible pump device 10 includes a cylindrical housing 20, a pump 22 provided inside the housing 20, a motor 23 provided inside the housing 20, an electrical unit 30 provided inside the housing 20, and a liquid level gauge 50 installed in the housing 20.

[0012] The liquid level gauge 50 is composed of, for example, a semiconductor pressure sensor and is positioned on the wall surface of the housing 20, preferably at the bottom of the housing 20. The liquid level gauge 50 measures the liquid level in the water storage tank 100. Specifically, since the pressure applied to the semiconductor pressure sensor changes according to the liquid level, the corresponding liquid level is measured from the pressure value. The liquid quality of the liquid stored in the water storage tank 100 varies widely, so the contact area between the liquid level gauge and the liquid must be made of a material that does not corrode or dissolve. Therefore, a configuration is envisioned in which oil is sealed between a diaphragm made of an elastic material such as fluororubber or a thin metal film material and a semiconductor pressure sensor, and the pressure applied to the elastic material or diaphragm (water pressure due to the liquid) is transmitted to the semiconductor pressure sensor via the oil to detect the liquid level.

[0013] The pump 22 is located inside the housing 20 and draws water from the water storage tank 100 through an opening 22a located at the bottom of the housing 20, and discharges it through a discharge port 22b. The motor 23 is, for example, a three-phase permanent magnet synchronous motor, a three-phase induction motor, or a single-phase induction motor, and drives the pump 22.

[0014] The electrical unit 30 comprises a control unit 31, an inverter 32, a time measurement unit 33, a current measurement unit 34, a temperature measurement unit 35, an operating frequency measurement unit 36, a storage unit 37, an input interface 38, and a wireless communication unit 39, each connected by a system bus.

[0015] The control unit 31 performs control based on the measured value of the liquid level gauge 50, the wireless signal of the wireless communication unit 39, and the wireless propagation status according to a predetermined program. When the pressure value is measured when the liquid level reaches the set liquid level L1 (first liquid level) by the liquid level gauge 50, the control unit 31 starts the pump 22. Similarly, when the liquid reaches the set liquid level L0 (second liquid level), the control unit 31 stops the pump 22.

[0016] Note that since the liquid level gauge 50 measures the pressure value based on the atmospheric pressure around the semiconductor pressure sensor (here, the air pressure inside the motor), when the temperature inside the motor rises, the atmospheric pressure around the semiconductor pressure sensor rises, so there may be an error between the measured value of the liquid level gauge and the actual liquid level. Therefore, the control unit 31 measures the temperature inside the motor for calibration and corrects the error between the measured value and the liquid level. Note that the correction process may be implemented inside the liquid level gauge 50. In addition, the control unit 31 can switch between the "constant frequency mode" and the "constant current value mode" as needed. The program for operating the control unit 31 is to cause the underwater pump device to perform either alternating operation or alternating parallel operation as described later.

[0017] The inverter 32 variably controls the motor 23 and transmits information on the applied current to the motor 23 and the operating frequency of the motor 23 to the control unit 31. The inverter 32 may include a current measurement sensor and a temperature measurement sensor.

[0018] The time measurement unit 33 measures the integrated operation time of the pump 22, the operation time since startup, etc. The current measurement unit 34 measures the current flowing through the motor 23. The temperature measurement unit 35 measures the temperatures of the electrical equipment unit 30 and the motor 23. The operating frequency measurement unit 36 measures the operating frequency related to the operation of the motor 23.

[0019] The memory unit 37 is, for example, a ROM (Read Only Memory) or RAM (Random Access Memory), and stores pump operation information and pump operation information obtained from other submersible pump devices. The input interface 38 accepts input from external devices.

[0020] The wireless communication unit 39 is equipped with wireless communication functions such as LTE (Long Term Evolution) (registered trademark), Bluetooth (registered trademark), and Wi-Fi. The wireless communication unit 39 determines the liquid level based on whether or not it can communicate wirelessly with the outside. In other words, if the wireless communication unit 39 cannot communicate wirelessly, it indicates that the wireless communication unit is in the liquid and the radio waves are attenuated by the liquid, so the liquid level is said to be above the position where the wireless communication unit 39 is located. On the other hand, if the wireless communication unit 39 can communicate wirelessly, it indicates that the wireless communication unit is not in the liquid, so the liquid level is said to be below the position where the wireless communication unit 39 is located. In the example in Figure 1, the wireless communication unit 39 is located in the center of the housing 20, but it is not limited to this, and may be located at the top of the housing 20 or at the bottom of the housing 20.

[0021] The control unit 31 may set, via the wireless communication unit 39, the number of submersible pump devices 1 or pumps 22, whether or not they are operated in parallel, the operating order, the starting liquid level of pump 22, the stopping liquid level, the starting liquid level for parallel operation, and at least one of the disconnection liquid level for disconnecting parallel operation.

[0022] In Figure 1, the set liquid level L1 is set near the top of the housing 20 of the submersible pump device 10, and the set liquid level L0 is set near the pump 22 of the housing 20. However, the positions of the set liquid levels L0 and L1 can be appropriately set according to the drainage environment provided by the pump.

[0023] Next, another example of the submersible pump device 10 is shown in Figure 2. Figure 2 shows a submersible pump device 10 in which the electrical components 30 are located outside the housing 20, for example, on the side of the housing 20. This makes maintenance of the electrical components 30, such as the wireless communication unit 39, easier. Since the electrical components 30 will be immersed in the liquid on their own, they should be covered with a shielding material made of metal or resin. Furthermore, the electrical components 30 can be treated with resin potting to prevent condensation and provide waterproofing. The liquid level gauge 50 may be located at the bottom of the electrical unit 30, which is located outside the housing 20.

[0024] Next, an example of the operation of the submersible pump device 10 according to this embodiment will be described with reference to the flowchart in Figure 3. In step SA1, after the user powers on the submersible pump device 10, the control unit 31 puts the submersible pump device 10 into a stopped state.

[0025] In step SA2, the liquid level gauge 50 measures the liquid level in the water storage tank 100 and obtains the measured liquid level. From this point onward, it is assumed that the liquid level is rising. In step SA3, the control unit 31 determines whether or not the starting liquid level has been reached. Specifically, if the liquid level measured by the liquid level gauge 50 has reached the set liquid level L1, the process proceeds to step SA4; if the measured liquid level has not reached the set liquid level L1, the process returns to step SA2 and repeats.

[0026] In step SA4, the control unit 31 starts the pump 22 to discharge the liquid from the water storage tank 100 because the liquid level has risen to the starting liquid level. From this point onward, it is assumed that the liquid level is decreasing. In step SA5, the control unit 31 determines whether the liquid level has reached the stop level. Specifically, if the liquid level measured by the liquid level gauge 50 has reached the set liquid level L0, the process proceeds to step SA6. If the measured liquid level has not reached the set liquid level L0, the determination process in step SA5 is repeated until the liquid level reaches the stop level.

[0027] In step SA6, the control unit 31 determines whether the stop condition is met. Here, the control unit 31 may determine that the stop condition for the pump 22 is met because the liquid level has reached the stop liquid level, based on the determination process using the liquid level gauge 50 measured in step SA5, or it may use other conditions for determination. For example, the stop condition may be determined using at least one of the current value and temperature. Specifically, when determining using the current value, the stop condition is determined based on the so-called "sounding water operation," which alternates between a dry running state where air enters the pump and an operation state where return water is drawn up from the discharge pipe during a drought. In the dry running state, the current value is lower than when water is being drawn up, and in the "sounding water operation," the current value changes periodically, resulting in a pulsating current. Therefore, based on the current value measured by the current measurement unit 34, the control unit 31 determines that the liquid level has reached the set liquid level L0 if a pulsating current is generated or if the current is below a predetermined value, and thus determines that the stop condition for the pump 22 is met.

[0028] Furthermore, when using temperature for determination, the current value remains high during pump operation. However, if the liquid level is above a certain level, the housing 20 and pump 22 are cooled by the liquid, maintaining the temperature within a predetermined range. The temperature rise after a preset period of time, used for measuring temperature changes, is also within a predetermined range. However, as the liquid level decreases, the housing 20 and pump 22 are no longer cooled by the liquid, and the temperature rises. Therefore, if the temperature of the motor 23 or electrical equipment 30 measured by the temperature measurement unit 35 exceeds a threshold, or if the temperature rise calculated from the temperature at the first point in time and the temperature at the second point in time after a preset period of time exceeds a threshold, the control unit 31 determines that the liquid level has reached the set liquid level L0, and thus determines that the conditions for stopping the pump 22 are met. If it is determined that the stopping conditions are met as described above, the process proceeds to step SA7. If it is determined that the stopping conditions are not met, the process returns to step SA5 and repeats the same process.

[0029] In step SA7, the control unit 31 controls the pump 22 to stop. Then, it returns to SA2 and continues to control the operation of the pump 22 using the liquid level gauge 50.

[0030] Alternatively, instead of the current measurement unit 34 and the temperature measurement unit 35, the current measurement sensor and temperature measurement sensor included in the inverter 32 may perform the same measurement processing, respectively. Furthermore, the wireless communication unit 39 may receive user instructions and perform a trial run to start or stop the pump 22. This allows the operation of the submersible pump device 1 to be confirmed even when there is no liquid in the water storage tank 100.

[0031] Next, Figure 4 shows an example configuration of a submersible pump system in which multiple submersible pump devices 10 exist. The submersible pump system shown in Figure 4 includes two submersible pump devices 10A and 10B located inside the water storage tank 100. While Figure 4 shows two submersible pump devices 10A and 10B, the system is not limited to this; three or more submersible pump devices 10 may be installed inside the water storage tank 100. The configurations of the submersible pump device 10A and the submersible pump device 10B are the same as those of the submersible pump device 10 shown in Figure 1. For the sake of explanation, they are distinguished by assigning the designations "A" and "B" to their symbols.

[0032] Here, the wireless communication unit 39A of the submersible pump device 10A communicates wirelessly with the wireless communication unit 39B of the other submersible pump device 10B, transmitting status signals (operating / stopped status, liquid level information, timer value, etc.) and instruction information for each other to allow or prohibit operation.

[0033] Furthermore, the wireless communication unit 39A of the submersible pump device 10A and the wireless communication unit 39B of the submersible pump device 10B exchange pump operation information. The pump operation information includes at least one of the following: operation mode, operation order, operation information, liquid level information, cumulative operation time, cumulative number of starts, identification number, failure history, and sensor information. The operation mode indicates which mode it is, for example, single operation mode, alternating operation mode, or alternating parallel operation mode. The operation order indicates whether it is the main unit that operates first or the slave unit that operates later, if the operation mode is alternating operation mode or alternating parallel operation mode. If three or more submersible pump devices 10 are configured, the operation order can be set even within the slave units, such as slave unit 1, slave unit 2, etc.

[0034] The operating information indicates the operating status of the submersible pump device 10, for example, whether the submersible pump device 10 is operating, stopped at low water level, stopped due to a malfunction, or an alarm is sounding. The liquid level information is the liquid level measured by the liquid level gauge 50. The identification number is a number that uniquely identifies the submersible pump device 10. The failure history shows information such as the location and date and time of the failure when the submersible pump device 10 failed. The sensor information is, for example, sensor information at the time of the failure of the submersible pump device 10, such as the temperature measured by the temperature measurement unit 35, the current value measured by the current measurement unit 34, and the operating frequency value measured by the operating frequency measurement unit 36. Based on the pump operation information, for example, the liquid level information detected by liquid level meter 50A and the liquid level information detected by liquid level meter 50B are exchanged. The acquired pump operation information of the other party is stored together with the own pump operation information in, for example, the storage unit 37.

[0035] The following describes the drainage operation performed by the submersible pump systems 10A and 10B configured as described above. First, the alternating operation will be explained according to the flow chart in Figure 5. The alternating operation is the operation in which only one of the submersible pump systems 10A or 10B is operated.

[0036] First, when the user turns on the power, the control unit 31A and control unit 31B start up. In step SB1, the control unit 31A confirms that the pump 22A has stopped operating, and the control unit 31B confirms that the pump 22B has stopped operating. In step SB2, the wireless communication unit 39A and the wireless communication unit 39B exchange pump operation information and set the assignment of the main and slave units. Methods for determining the main and slave units include, for example, exchanging information on cumulative operating time or cumulative start-up counts, and setting the one with the shorter cumulative operating time or fewer cumulative start-up counts as the main unit. Alternatively, they can randomly determine values, and the one with the larger determined value is set as the main unit. In this case, the submersible pump device 10A is set as the main unit, and the submersible pump device 10B is set as the slave unit. Note that, for example, a user may directly assign the main and slave units via wireless communication between a mobile terminal and the wireless communication unit 39A and the wireless communication unit 39B.

[0037] In step SB3, the liquid level meter 50A measures the liquid level. In step SB4, the control unit 31A determines whether the starting liquid level has been reached. That is, if the liquid level measured by the liquid level gauge 50 has reached the set liquid level L1, the process proceeds to step SB5; if the measured liquid level has not reached the set liquid level L1, the process returns to step SA3 and the same process is repeated.

[0038] In step SB5, when the liquid level reaches the starting liquid level, the control unit 31A starts the pump 22A. Information that the pump 22A is starting is transmitted from the wireless communication unit 39A to the control unit 31B of the submersible pump device 10B. In the following, we will assume that the liquid level drops because the pump 22A has been started.

[0039] In step SB6, the control unit 31A determines whether the liquid level has reached the stop level. If the liquid level has reached the stop level, it can be determined that the liquid level in the water storage tank 100 has decreased. If the liquid level has reached the stop level, the process proceeds to step SB7; otherwise, the pump continues draining and the determination process in step SB6 is repeated. Note that if the pump 22 is operated, the liquid level should decrease and eventually reach the stop level. However, if the liquid level does not decrease even when the pump 22 is operating, the control unit 31 may increase the operating frequency of the motor 23A and rotate it at high speed to increase the drainage capacity of the pump 22.

[0040] In step SB7, the control unit 31A determines whether the stop condition is met. Here, it is assumed that the liquid level has reached the stop liquid level, so the stop condition is met and the process proceeds to step SB8. In addition, the stop condition may be determined by performing a threshold determination based on the measured current or temperature as described in the explanation of Figure 3. For example, the control unit 31A may determine that the stop condition is met if a pulsating current is generated.

[0041] In step SB8, the control unit 31A stops the pump 22A. In step SB9, the wireless communication unit 39A and the wireless communication unit 39B communicate with each other to set up the main and slave units to switch roles. After the pump 22A stops, the control unit 31A sets itself as the slave unit and transmits stop information indicating that the pump 22A has stopped from the wireless communication unit 39A to the wireless communication unit 39B. Upon receiving the stop information of the pump 22A from the wireless communication unit 39B, the control unit 31B sets its own submersible pump device 10B as the main unit.

[0042] Subsequently, the control unit 31B performs the role of the main unit of the submersible pump device 10A from step SB1 to step SB9. In this way, alternating operation of multiple submersible pump devices 10A can be achieved through the use of float switches and wireless communication.

[0043] In this way, when the submersible pump system, including submersible pump unit 10A and submersible pump unit 10B, is operated alternately, the set liquid level L1, which is the starting liquid level for submersible pump unit 10A and submersible pump unit 10B, can be appropriately measured by the liquid level gauge 50. Furthermore, by alternating the starting operations, the operating time can be leveled out, thereby reducing maintenance costs.

[0044] Next, an example of alternating parallel operation of the submersible pump device 10 according to this embodiment will be described with reference to the flowcharts in Figures 6 and 7. Alternating parallel operation is a method in which, when the set liquid level L1 is exceeded, one of the submersible pumps 10A or 10B is started first, and if the liquid level does not fall below the set liquid level L1 after some time has passed, both pumps are operated.

[0045] First, when the user turns on the power, the control unit 31A and control unit 31B start up. Steps SB1 through SB5 are the same as those shown in Figure 5, and this is the case when the submersible pump device 10A is operating independently.

[0046] In step SC1, the control unit 31B determines whether the liquid level remains above the starting liquid level after a predetermined time has elapsed since the pump of the submersible pump device 10A started. The time can be measured by the time measurement unit 33, and the liquid level can be measured by the liquid level gauge 50B. If the liquid level remains above the starting liquid level after the predetermined time has elapsed, the process proceeds to step SC2; otherwise, the alternating operation of the submersible pump device 10A and the submersible pump device 10B shown in Figure 5 can be performed.

[0047] In step SC2, the control unit 31B starts the submersible pump device 10B. That is, simply starting the pump of the submersible pump device 10A would not reduce the liquid level, and if the pump of the submersible pump device 10A were to continue operating alone, there is a possibility that the water would overflow from the storage tank 100. Therefore, parallel operation is performed in which the submersible pump device 10B is also operated at the same time.

[0048] In step SC3, the control unit 31B determines whether the liquid level has reached the stop level. If the liquid level has reached the stop level, the process proceeds to step SB9. If the liquid level has not reached the stop level, the determination process in step SC3 continues while the pump operation continues. Note that if parallel operation continues, the liquid level should decrease. However, if the liquid level does not decrease even in parallel operation, the control units 31A and 31B may increase the operating frequency of motors 23A and 23B respectively, causing them to rotate at high speed, thereby increasing the drainage capacity of pumps 22A and 22B.

[0049] In the example shown in Figure 7, it is assumed that the liquid level decreases due to parallel operation, enabling wireless communication by the wireless communication unit 39, and that the submersible pump device 10A stops as the stop conditions are met. Subsequently, in step SB9, the main and slave pumps are switched between the submersible pump devices 10 through communication between the wireless communication unit 39A and the wireless communication unit 39B.

[0050] In step SC4, the control unit 31B determines whether the stopping conditions for the pump 22B are met. The stopping conditions can be determined using the same criteria as in step SB7. If the stopping conditions are met, the process proceeds to step SC5. If the stopping conditions are not met, the process proceeds to the steps shown in Figure 7.

[0051] In step SC5, the control unit 31B stops the pump 22B. After that, the submersible pump device 10B performs the operation of the main unit, and the submersible pump device 10A performs the operation of the slave unit, and the same process is repeated alternately.

[0052] Next, Figure 7 shows an example of operation of the submersible pump device 10 when the stopping conditions are not met in step SC4. Here, we assume that, as a result of the process in step SB9, the submersible pump device 10A is set as a slave unit via wireless communication after it has stopped, and the submersible pump device 10B is set as the main unit via wireless communication while it is running, after which parallel operation is canceled. However, we assume that the drainage is not sufficient with only one submersible pump device 10B, the liquid level continues to rise, wireless communication between the wireless communication unit 39A and the wireless communication unit 39B becomes impossible, and the liquid level rises again to the starting liquid level.

[0053] In step SD1, the control unit 31A determines whether the liquid level remains above the starting liquid level even after a predetermined time has elapsed since the pump of the submersible pump device 10B started. If the liquid level remains above the starting liquid level after the predetermined time has elapsed, the process proceeds to step SD2; otherwise, the alternating operation of the submersible pump device 10A and the submersible pump device 10B shown in Figure 5 is performed.

[0054] In step SD2, the control unit 31A starts the submersible pump device 10A and performs parallel operation of the submersible pump device 10A and the submersible pump device 10B. After that, the roles of the submersible pump devices 10A and 10B are reversed, so a detailed explanation is omitted.

[0055] In addition, depending on the actual operating environment, if the main and slave units are switched between the two submersible pump systems 10 each time the pump stops, the cumulative operating time and cumulative number of starts may not be averaged, and a bias may occur where one submersible pump system has a shorter operating time. In this case, instead of switching the main and slave units alternately, the cumulative operating time or cumulative number of starts can be transmitted and received between the wireless communication units 39 at the start of operation, and the submersible pump system 10 with the shorter cumulative operating time or cumulative number of starts can be started as the main unit. As a result, one submersible pump system 10 may operate as the main unit continuously, but the timing of maintenance for multiple submersible pump systems 10 can be synchronized, enabling efficient operation.

[0056] Furthermore, in the case of multiple submersible pump devices 10, it is conceivable that the switching between main and slave units may not be properly configured, resulting in multiple submersible pump devices 10 being configured as main units and starting simultaneously, or in some cases, none of the submersible pump devices 10 being configured as main units and none starting. In such cases, the memory unit 37 can be used to store that one of the submersible pump devices 10 is the "priority unit," and if multiple units are configured as main units or if no main units are configured, the control unit 31 can perform a reset operation between the submersible pump devices 10 via wireless communication, so that the "priority unit" is configured as the main unit and the other submersible pump devices 10 are configured as slave units.

[0057] Although an example has been described in which the operating order of the main and slave pumps is determined by exchanging pump operation information between multiple submersible pump devices 10, the method is not limited to this. Each submersible pump device 10 may receive instructions to switch between alternating operation mode and alternating parallel operation mode from an external terminal capable of sending user instructions, and the control unit 31 of each submersible pump device 10 may switch between the alternating operation mode and the alternating parallel operation mode in accordance with the switching instructions.

[0058] Furthermore, a determination of the liquid level may be performed depending on whether or not wireless communication is possible by the wireless communication unit 39. As described above, if wireless communication is possible between the wireless communication units 39 of the multiple submersible pump devices 10, it can be determined that the liquid level is lower than the location where the wireless communication unit 39 is located, and if wireless communication is not possible, it can be determined that the liquid level is higher than the location where the wireless communication unit 39 is located. Therefore, for example, in Figure 6, if it can be determined that wireless communication is possible by the wireless communication unit 39 at a stage before step SB5, it can be determined that the liquid level is lower than the location where the wireless communication unit 39 is located, and this can be used as reinforcing evidence for the liquid level determination by the liquid level gauge 50 that the liquid level has reached the stop liquid level. By also performing liquid level determination by the wireless communication unit 39 in this manner, the accuracy of liquid level determination can be improved.

[0059] As shown in Figures 5 to 7, when installing multiple submersible pump devices 10, in this case two submersible pump devices 10A and submersible pump device 10B, the configurations of submersible pump devices 10A and 10B can be made identical, which also reduces the manufacturing cost per pump device.

[0060] Furthermore, although it was explained that control units 31A and 31B switch between "constant frequency mode" and "constant current value mode" as needed, it is also possible to set both "constant frequency mode" and "constant current value mode" simultaneously.

[0061] According to the embodiment described above, a liquid level meter using a semiconductor pressure sensor measures the liquid level in the tank and controls the starting and stopping of the pump. By using this liquid level meter, there is no need to reserve space for a float switch or a submersible water level meter, enabling high-precision liquid level control while saving space. Furthermore, a wireless communication unit is provided, allowing the pump to be started and stopped wirelessly, and by exchanging operating information about the pumps between multiple submersible pump devices, it is possible to switch between main and slave pumps during alternating operation and alternating parallel operation. In this way, simple and diverse liquid level control can be performed.

[0062] It should be noted that the present invention is not limited to the embodiments described above, and can be modified in various ways during implementation without departing from its essence. Furthermore, each embodiment may be combined as appropriate, and in that case, the combined effects can be obtained. Moreover, the above embodiments include various inventions, and various inventions can be extracted by selecting combinations from the multiple constituent elements disclosed. For example, if the problem can be solved and effects obtained even if some constituent elements are deleted from all the constituent elements shown in the embodiment, then the configuration with these deleted constituent elements can be extracted as an invention. [Explanation of Symbols]

[0063] 10... Submersible pump device, 20... Housing, 22... Pump, 22a... Opening, 22b... Discharge port, 23... Motor, 30... Electrical unit, 31... Control unit, 32... Inverter, 33... Time measurement unit, 34... Current measurement unit, 35... Temperature measurement unit, 36... Operating frequency measurement unit, 37... Memory unit, 38... Input interface, 39... Wireless communication unit, 50... Liquid level meter, 100... Water storage tank, 200... External piping.

Claims

1. A pump located inside the enclosure, A motor is provided inside the housing to drive the pump, A liquid level meter is provided in the housing and positioned at the bottom of the housing, which measures a pressure value based on the air pressure inside the motor, which is the atmospheric pressure around the semiconductor pressure sensor, and measures the liquid level from the pressure value. A control unit that controls the pump to start or stop according to the liquid level measured by the liquid level meter, The housing is provided with an electrical component unit including the control unit, It is equipped with, The electrical unit includes a temperature measuring unit for measuring the temperature inside the housing, The control unit corrects the liquid level measured by the liquid level meter according to the temperature measured by the temperature measuring unit. Submersible pump device.

2. The aforementioned liquid level meter has oil sealed between an elastic material or diaphragm and the semiconductor pressure sensor. The submersible pump device according to claim 1, wherein the pressure applied to the elastic material or the diaphragm is transmitted to the semiconductor pressure sensor via the oil, thereby measuring the pressure.

3. The system further comprises a current measuring unit for measuring the current flowing through the motor, The submersible pump device according to claim 1, wherein the control unit controls the pump to stop when the current measuring unit measures that the current is pulsating or that the current value is below a predetermined value.

4. The inverter further includes a current measuring sensor that controls the motor at a variable speed and measures the current flowing through the motor, and a temperature measuring sensor that measures the temperature of at least one of the electrical components, including the motor and the control unit. The submersible pump device according to claim 1, wherein the control unit controls the pump to stop if the current measurement sensor detects that the current is pulsating or is below a predetermined value, or if the temperature measurement sensor detects that the temperature is above a first threshold, or if the temperature rise calculated from the temperature at a first time point and the temperature at a second time point after a predetermined time has elapsed from the first time point is above a second threshold.

5. The submersible pump device according to claim 4, wherein the electrical component including the control unit is located on the side of the housing, and the liquid level meter is located below the electrical component.

6. It is further equipped with a wireless communication unit for wireless communication with the outside world, The submersible pump device according to claim 1, wherein, during pump operation, if the liquid reaches a stop level for stopping the pump or a disconnection level for canceling the multi-unit control operation, but the wireless communication unit is unable to continuously transmit wireless communication for a predetermined time, the control unit switches to a single-unit operation mode in which the multi-unit control operation is not performed.

7. It is further equipped with a wireless communication unit for wireless communication with the outside world, The submersible pump device according to claim 1, wherein the control unit sets at least one of the following liquid levels based on instructions from the outside via wireless communication: a starting liquid level for starting the pump, a stopping liquid level for stopping the pump, a starting liquid level for starting parallel operation of multiple pumps, and a disconnection liquid level for discontinuing the parallel operation.

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