Drainage pump control device, drainage device, and drainage pump control method

Abstract

A drainage pump control device, a drainage device, and a drainage pump control method that can reduce power consumption. [Solution] The drainage pump control device 101 comprises a first sensor 26 that detects a first water level state in which the water level of the water to be discharged is equal to or higher than a first water level, an inverter circuit 23 that supplies AC power to a motor 22 that drives a pump 21 that discharges water, and a control unit 33 that, when the first water level state is detected by the first sensor 26, starts control to supply AC power of a first frequency to the inverter circuit 23, and when the detection of the first water level state continues for a first predetermined time after starting control, the control unit 33 causes the inverter circuit 23 to supply AC power of a second frequency that is higher than the first frequency and lower than the rated frequency that rotates the motor at the rated rotational speed.

Description

[Technical Field]

[0001] The present invention relates to a drainage pump control device, a drainage device, and a drainage pump control method. [Background technology]

[0002] There is an operation control method for performing drainage work using a drainage pump whose rotation speed is controlled by an inverter (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-13912 Summary of the Invention [Problem to be solved by the invention]

[0004] In the operation control method for a drainage pump for equipment described in Patent Document 1, the inverter operates the pump at a speed slower than the rated rotation speed to save energy, and when the water level rises due to an abnormal increase in water in the tank, a detection signal from a water level detector is input to the inverter, causing the pump to speed up to the rated rotation speed and operate at a more powerful speed so that the amount of drainage increases. There is a demand for technology that goes beyond this operation control method and reduces power consumption.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a drainage pump control device, a drainage device, and a drainage pump control method that are capable of reducing power consumption. [Means for solving the problem]

[0006] A drainage pump control device according to one embodiment of the present invention comprises a first sensor that detects a first water level state in which the water level of the water to be discharged is equal to or higher than a first water level, an inverter circuit that supplies AC power to a motor that drives a pump that discharges water, and a control unit that, when the first water level state is detected by the first sensor, starts control to supply AC power of a first frequency to the inverter circuit, and when the detection of the first water level state continues for a first predetermined time after starting control, the control unit causes the inverter circuit to supply AC power of a second frequency that is higher than the first frequency and lower than a rated frequency that rotates the motor at a rated rotational speed.

[0007] In the above aspect, when the detection of the first water level state continues for a second predetermined time, the control unit may cause the inverter circuit to supply AC power at a third frequency that is higher than the second frequency and lower than the rated frequency.

[0008] In the above aspect, the drainage pump control device may further include a second sensor that detects a second water level state in which the water level is at or above a second water level that is higher than the first water level, and the control unit may supply AC power of the rated frequency to the inverter circuit when the second water level state is detected by the second sensor.

[0009] In the above aspect, the control unit may end control of supplying AC power to the inverter circuit when the first water level state is no longer detected by the first sensor.

[0010] In the above aspect, when the first water level state is detected again by the first sensor, the control unit may start control to supply AC power of the first frequency to the inverter circuit.

[0011] In the above aspect, the drainage pump control device further includes a memory unit, and the control unit is capable of controlling the inverter circuit to supply AC power of at least one frequency higher than the second frequency and lower than the rated frequency, in addition to the second frequency, and when controlling the inverter circuit to supply AC power of a fourth frequency higher than the second frequency and lower than the rated frequency, when the first water level state is no longer detected by the first sensor, information indicating the fourth frequency may be stored in the memory unit and the control to supply AC power to the inverter circuit may be terminated.

[0012] In the above aspect, when the first water level state is detected again by the first sensor, the control unit may start control to supply AC power of the fourth frequency to the inverter circuit based on the detected information.

[0013] In the above aspect, the control unit may terminate control of supplying AC power to the inverter circuit when the first water level state is no longer detected by the first sensor before a third predetermined time has elapsed since starting control of supplying AC power of the fourth frequency to the inverter circuit, and store information in the memory unit indicating a fifth frequency that is lower than the fourth frequency and equal to or greater than the first frequency.

[0014] In the above aspect, the control unit may cause the inverter circuit to supply AC power of a sixth frequency that is higher than the fourth frequency but lower than the rated frequency when detection of the first water level state continues for a third predetermined time after starting control to supply AC power of a fourth frequency to the inverter circuit.

[0015] In the above aspect, the drainage pump control device further includes a memory unit, and the control unit is capable of controlling the inverter circuit to supply AC power of at least one frequency higher than the second frequency and lower than the rated frequency, in addition to the second frequency, and when controlling the inverter circuit to supply AC power of a fourth frequency higher than the second frequency and lower than the rated frequency, when the first water level state is no longer detected by the first sensor, information indicating the fourth frequency or a fifth frequency lower than the fourth frequency and higher than the first frequency may be stored in the memory unit, and the control to supply AC power to the inverter circuit may be terminated.

[0016] In the above aspect, when the first water level state is detected again by the first sensor, the control unit may start control to supply AC power of the fifth frequency to the inverter circuit based on the detected information.

[0017] In the above aspect, the control unit may terminate the control of supplying AC power to the inverter circuit after a fourth predetermined time has elapsed when the first water level state is no longer detected by the first sensor.

[0018] A drainage device according to one aspect of the present invention includes a drainage pump control device, a motor, and a pump.

[0019] A drainage pump control method according to one embodiment of the present invention is a drainage pump control method in a drainage pump control device that includes a first sensor that detects a first water level state in which the water level of the water to be discharged is equal to or higher than a first water level, and an inverter circuit that supplies AC power to a motor that drives a pump that discharges water, and includes the steps of: when the first water level state is detected by the first sensor, starting control to supply AC power of a first frequency to the inverter circuit; and when detection of the first water level state continues for a first predetermined time after the start of control, causing the inverter circuit to supply AC power of a second frequency that is higher than the first frequency and lower than a rated frequency that rotates the motor at a rated rotational speed. [Effects of the Invention]

[0020] According to the present invention, it is possible to provide a drainage pump control device, a drainage device, and a drainage pump control method that are capable of reducing power consumption. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a schematic diagram showing a drainage device 11 according to a first embodiment of the present invention. [Figure 2] 2 is a functional block diagram showing each function of a microcomputer 25 according to the first embodiment of the present invention. FIG. [Figure 3] 3 is a flowchart showing a drainage pump control method executed by the drainage pump control device according to the first embodiment of the present invention. [Figure 4] 3 is a flowchart showing a control switching process in the drainage pump control device 101 according to the first embodiment of the present invention. [Figure 5] 4 is a time chart showing an example of changes over time in the level of a first signal, the level of a second signal, the operating frequency, the impeller rotation speed, and the water level according to the first embodiment of the present invention. [Figure 6] 6 is a time chart showing another example of changes over time in the level of the first signal, the level of the second signal, the operating frequency, the impeller rotation speed, and the water level according to the first embodiment of the present invention. [Figure 7] FIG. 10 is a functional block diagram showing each function of a microcomputer 125 according to a second embodiment of the present invention. [Figure 8] 6 is a flowchart showing a drainage pump control method executed by a drainage pump control device according to a second embodiment of the present invention. [Figure 9] 10 is a flowchart showing a control switching process in a drainage pump control device 101 according to a second embodiment of the present invention. [Figure 10] 10 is a flowchart showing a modified example of the drainage pump control method executed by the drainage pump control device according to the second embodiment of the present invention. [Figure 11] 10 is a flowchart showing a modified example of the control switching process in the drainage pump control device 101 according to the second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Note that the embodiment described below is merely a specific example for carrying out the present invention and is not intended to limit the present invention. Furthermore, to facilitate understanding of the description, the same components in each drawing will be assigned the same reference numerals as much as possible, and duplicate descriptions may be omitted.

[0023] First Embodiment [Outline of drainage system] Fig. 1 is a schematic diagram showing a drainage device 11 according to a first embodiment of the present invention. As shown in Fig. 1, the drainage device 11 includes a housing 20, a pump 21, a motor 22, an inverter circuit 23, a DC power generation circuit 24, and a drainage pump control device 101. The drainage pump control device 101 includes a microcomputer 25, a lower water surface detection electrode 26, and an upper water surface detection electrode 27.

[0024] The drainage device 11 is installed, for example, on the bottom 201a of a tank 201 for temporarily storing construction water 211 to be discharged. The pump 21, the motor 22, the inverter circuit 23, and the DC power generation circuit 24 are housed, for example, in a housing 20.

[0025] The drainage device 11 may be completely submerged when the water level rises. For this reason, the housing 20 and the microcomputer 25 are waterproof. The lower water surface detection electrode 26 and the upper water surface detection electrode 27 are exposed, so they come into contact with the construction water 211 when the water level rises.

[0026] The pump 21 has a water intake port and a drain port (not shown). The drain port of the pump 21 is connected to the outside of the tank 201 through a pipe member (not shown). The pipe member is, for example, a Sunny Hose (registered trademark). The pump 21 is driven by the motor 22 to discharge the construction water 211 out of the tank 201.

[0027] The motor 22 drives the pump 21 using AC power supplied from the inverter circuit 23. Specifically, the motor 22 is, for example, an induction motor. The rotating shaft of the motor 22 is connected to the impeller of the pump 21 and rotates at a rotation speed corresponding to the frequency of the AC power (hereinafter, sometimes referred to as the operating frequency). In other words, when the rotation speed reaches a steady state, the rotation speed of the impeller of the pump 21 when the operating frequency is low is lower than the rotation speed of the impeller of the pump 21 when the operating frequency is high.

[0028] The DC power generation circuit 24 includes, for example, a rectifier circuit and a converter circuit, and converts single-phase or three-phase AC power into DC power and outputs it to the inverter circuit 23.

[0029] The inverter circuit 23 supplies AC power to the motor 22 under the control of the microcomputer 25. In particular, the inverter circuit 23 generates AC power based on DC power supplied from the DC power generation circuit 24, and outputs the generated AC power to the motor 22. The operating frequency of the AC power generated by the inverter circuit 23 is variable under the control of the microcomputer 25.

[0030] The lower water surface detection electrode 26 (an example of a "first sensor") detects a first water level state in which the water surface 211a of the construction water 211 is equal to or higher than the water level WL1 (an example of a "first water level"). In detail, the lower water surface detection electrode 26 outputs to the microcomputer 25, for example, a first signal having a level corresponding to whether or not the water level of the construction water 211 is equal to or higher than the water level WL1.

[0031] When the water level of the construction water 211 is equal to or higher than the water level WL1, the level of the first signal is, for example, the ON level. On the other hand, when the water level of the construction water 211 is lower than the water level WL1, the level of the first signal is, for example, the OFF level. In other words, when the level of the first signal is the ON level, it is in the first water level state. In this embodiment, the water level is the depth from the water surface 211a of the construction water 211 to the bottom 201a of the tank 201.

[0032] The upper water surface detection electrode 27 (an example of a "second sensor") detects a second water level state in which the water surface 211a of the construction water 211 is equal to or higher than the water level WL2 (an example of a "second water level"). Here, the water level WL2 is higher than the water level WL1. In detail, the upper water surface detection electrode 27 outputs to the microcomputer 25, for example, a second signal having a level corresponding to whether or not the water level of the construction water 211 is equal to or higher than the water level WL2.

[0033] When the water level of the construction water 211 is equal to or higher than the water level WL2, the level of the second signal is, for example, the ON level. On the other hand, when the water level of the construction water 211 is lower than the water level WL2, the level of the second signal is, for example, the OFF level. In other words, when the level of the second signal is the ON level, it is in the second water level state. In the example shown in FIG. 1, the water level WL3 of the construction water 211 is higher than the water level WL2, so it is in the second water level state.

[0034] [Configuration of drainage pump control device] 2 is a functional block diagram showing each function of the microcomputer 25 according to the first embodiment of the present invention. The drainage pump control device 101 is configured, for example, by causing a processor in the microcomputer 25 to execute a drainage pump control program, which is an example of a program.

[0035] As shown in FIG. 2, the microcomputer 25 includes an inverter circuit control unit 33 and a timer unit 34 as functional blocks.

[0036] When the first water level state is detected by the lower water surface detection electrode 26, the inverter circuit control unit 33 starts control to supply AC power of frequency F1 (an example of the "first frequency") to the inverter circuit 23.

[0037] In detail, the inverter circuit control unit 33 monitors the level of the first signal received from the lower water surface detection electrode 26. When the level of the first signal transitions from the off level to the on level, the inverter circuit control unit 33 recognizes that the first water level state has been detected by the lower water surface detection electrode 26, and starts control (hereinafter, sometimes referred to as control C1) to supply AC power of frequency F1 to the inverter circuit 23.

[0038] When the detection of the first water level state continues for a first predetermined time after starting control C1, the inverter circuit control unit 33 supplies AC power to the inverter circuit 23 at a frequency F2 (an example of a "second frequency") that is higher than frequency F1 and lower than the rated frequency that rotates the motor 22 at the rated rotational speed.

[0039] Specifically, the inverter circuit control unit 33 sets a first predetermined time in the timer unit 34 at the timing of starting the control C1. The first predetermined time is, for example, about 5 to 20 seconds.

[0040] The timer unit 34 operates according to a setting value of the inverter circuit control unit 33, and notifies the inverter circuit control unit 33 of expiration when the first predetermined time has elapsed since the first predetermined time was set by the inverter circuit control unit 33.

[0041] The inverter circuit control unit 33 monitors the level of the first signal from the timing when the first predetermined time is set in the timer unit 34, and when the on level of the first signal continues until it receives a notification of expiration from the timer unit 34, it performs control (hereinafter sometimes referred to as control C2) to supply AC power of frequency F2 to the inverter circuit 23.

[0042] When the detection of the first water level state continues for a second predetermined time, the inverter circuit control unit 33 causes the inverter circuit 23 to supply AC power at a frequency F3 (an example of a "third frequency") that is higher than the second frequency and lower than the rated frequency.

[0043] Specifically, the inverter circuit control unit 33 sets a second predetermined time in the timer unit 34 at the timing when control C1 is switched to control C2. The second predetermined time is, for example, about 5 to 20 seconds. The second predetermined time may be the same as or different from the first predetermined time.

[0044] When the second predetermined time has elapsed since the second predetermined time was set by the inverter circuit control unit 33, the timer unit 34 notifies the inverter circuit control unit 33 of expiration.

[0045] The inverter circuit control unit 33 monitors the level of the first signal from the timing when control C1 is switched to control C2, i.e., the timing when the second predetermined time is set in the timer unit 34. When the on level of the first signal continues until the inverter circuit control unit 33 receives a notification of expiration from the timer unit 34, the inverter circuit control unit 33 performs control (hereinafter, sometimes referred to as control C3) to supply AC power of frequency F3 to the inverter circuit 23.

[0046] When the upper water level detection electrode 27 detects the second water level state, the inverter circuit control unit 33 causes the inverter circuit 23 to supply AC power at the rated frequency.

[0047] In detail, when the inverter circuit control unit 33 is performing control C1, C2, or C3, it monitors the level of the second signal received from the upper water surface detection electrode 27. When the level of the second signal transitions from the off level to the on level, the inverter circuit control unit 33 switches from the currently performed control C1, C2, or C3 to control that supplies AC power of the rated frequency to the inverter circuit 23 (hereinafter, sometimes referred to as control Cr).

[0048] When the first water level state is no longer detected by the lower water surface detection electrode 26, the inverter circuit control unit 33 ends the control of supplying AC power to the inverter circuit 23.

[0049] In detail, when the inverter circuit control unit 33 is performing control C1, C2, C3 or Cr, when the level of the first signal transitions from an on level to an off level, it recognizes that the first water level state is no longer detected by the lower water surface detection electrode 26.

[0050] Then, the inverter circuit control unit 33 ends the currently executed control C1, C2, C3, or Cr, thereby stopping the supply of AC power from the inverter circuit 23 to the motor 22.

[0051] In addition, when the first water level state is no longer detected by the lower water surface detection electrode 26, the inverter circuit control unit 33 may set a predetermined time in the timer unit 34 and terminate C1, C2, C3 or Cr when it receives a notification of expiration from the timer unit 34.

[0052] After ending control C1, C2, C3 or Cr, the inverter circuit control unit 33 starts control C1 when the first water level state is detected again by the lower water surface detection electrode 26.

[0053] The lower the operating frequency, the more effective it is in reducing power consumption. Therefore, by configuring the system to resume control C1 as described above when the water level rises again, power consumption can be effectively reduced.

[0054] [Drainage pump control method] Next, a drainage pump control method according to the first embodiment of the present invention will be described in detail. Fig. 3 is a flowchart showing the drainage pump control method executed by the drainage pump control device according to the first embodiment of the present invention. As shown in Fig. 3, the drainage pump control method includes steps S102 to S108, and each step is executed by a processor included in the microcomputer 25.

[0055] First, the drainage pump control device 101 monitors the level of the first signal received from the lower water surface detection electrode 26, and if the level is the off level, continues monitoring (NO in step S102).

[0056] Next, when the level of the first signal transitions from the OFF level to the ON level (YES in step S102), the drainage pump control device 101 starts controlling the inverter circuit 23 (step S104).

[0057] Next, the drainage pump control device 101 performs a control switching process (step S106). The control switching process will be described in detail later.

[0058] Next, the drainage pump control device 101 ends the control of the inverter circuit 23 (step S108).

[0059] Next, the drainage pump control device 101 monitors the level of the first signal received from the lower water surface detection electrode 26, and continues monitoring if the level is the off level (NO in step S102).

[0060] 4 is a flowchart showing the control switching process in the drainage pump control device 101 according to the first embodiment of the present invention. FIG. 4 shows details of the operation in step S106 in FIG.

[0061] As shown in FIG. 4, first, the drainage pump control device 101 starts the control C1 (step S202).

[0062] Next, the drainage pump control device 101 sets a first predetermined time in the timer unit 34 and activates the timer unit 34 (step S204).

[0063] Next, when the level of the first signal is at the on level and the level of the second signal is at the off level (YES in step S206 and NO in step S208), the drainage pump control device 101 monitors the level of the first signal and the level of the second signal until the timer unit 34 expires (NO in step S210).

[0064] Next, when the timer unit 34 expires while the level of the first signal is at the on level and the level of the second signal is at the off level (YES in step S206, NO in step S208, and YES in step S210), if control C1 is being performed (YES in step S212), the drainage pump control device 101 switches control C1 to control C2 (step S214).

[0065] Next, the drainage pump control device 101 sets a second predetermined time in the timer unit 34 and activates the timer unit 34 (step S204).

[0066] On the other hand, when the timer unit 34 expires while the level of the first signal is at the on level and the level of the second signal is at the off level (YES in step S206, NO in step S208, and YES in step S210), the drainage pump control device 101 switches from control C2 to control C3 (step S216) while performing control C2 (NO in step S212).

[0067] Next, the drainage pump control device 101 monitors the level of the first signal and the level of the second signal (YES in step S218 and NO in step S220) until the level of the first signal transitions from the on level to the off level or the level of the second signal transitions from the off level to the on level (NO in step S218 or YES in step S220).

[0068] In addition, the drainage pump control device 101 terminates the control switching process when the level of the first signal transitions to the off level before the timer unit 34 expires (NO in step S206, NO in step S208, and NO in step S210), or when the level of the first signal transitions to the off level while control C3 is being performed (NO in step S218 and NO in step S220).

[0069] In addition, when the level of the second signal transitions to the on level before the timer unit 34 expires (YES in step S206, YES in step S208, and NO in step S210), or when the level of the second signal transitions to the on level while control C3 is being performed (YES in step S218 and YES in step S220), the drainage pump control device 101 switches control C1, C2, or C3 to control Cr (step S222).

[0070] Next, the drainage pump control device 101 continues the control Cr while the level of the first signal is at the on level (YES in step S224), and ends the control switching process when the level of the first signal transitions to the off level (NO in step S224).

[0071] In this way, when the drainage device 11 starts operating, the motor 22 is not suddenly operated at the rated frequency Fr, but the rotation speed of the motor 22 is increased in stages, thereby making it possible to reduce power consumption.

[0072] [Example 1] FIG. 5 is a time chart showing an example of changes over time in the level of the first signal, the level of the second signal, the operating frequency, the impeller rotation speed, and the water level according to the first embodiment of the present invention.

[0073] 5, the level of the first signal transitions from the OFF level to the ON level at timing t1 when the water level reaches or exceeds WL1. The microcomputer 25 starts control C1 at timing t1. In control C1, instead of suddenly supplying AC power of frequency F1 to the inverter circuit 23, the frequency of the AC power supplied by the inverter circuit 23 may be increased linearly from zero to frequency F1 over a predetermined time. The same applies to controls C2, C3, and Cr.

[0074] In accordance with control C1, inverter circuit 23 linearly increases the frequency of AC power supplied to motor 22 to frequency F1 over a predetermined time from time t1. The rotational speed of the shaft of motor 22, i.e., the rotational speed of the impeller of pump 21, becomes R1 in a steady state after the predetermined time has elapsed from time t1.

[0075] As the impeller of the pump 21 rotates at the rotation speed R1, the water level decreases, and at timing t2 when the water level becomes lower than WL1, the level of the first signal transitions from the ON level to the OFF level. The microcomputer 25 ends control C1 at timing t2.

[0076] The level of the first signal transitions from the OFF level to the ON level at timing t3 when the water level again becomes equal to or higher than WL1. The microcomputer 25 starts control C1 at timing t3.

[0077] In accordance with control C1, inverter circuit 23 linearly increases the frequency of AC power supplied to motor 22 to frequency F1 over a predetermined time from time t3. The rotation speed of the impeller of pump 21 reaches R1 in a steady state after the predetermined time has elapsed from time t3.

[0078] Since the water level continues to rise even though the impeller of the pump 21 rotates at the rotation speed R1, the microcomputer 25 switches from control C1 to control C2 at time t4, which is when the first predetermined time P1 has elapsed since time t3.

[0079] In accordance with control C2, inverter circuit 23 linearly increases the frequency of AC power supplied to motor 22 to frequency F2 over a predetermined time from time t4. The rotation speed of the impeller of pump 21 reaches R2, which is greater than R1, in a steady state after the predetermined time has elapsed from time t4.

[0080] As the impeller of the pump 21 rotates at the rotation speed R2, the water level decreases, and at timing t5 when the water level becomes lower than WL1, the level of the first signal transitions from the ON level to the OFF level. The microcomputer 25 ends control C2 at timing t5.

[0081] The level of the first signal transitions from the OFF level to the ON level at timing t6 when the water level reaches or exceeds WL1 three times. The microcomputer 25 starts control C1 at timing t6.

[0082] In accordance with control C1, inverter circuit 23 linearly increases the frequency of AC power supplied to motor 22 to frequency F1 over a predetermined time from time t6. The rotation speed of the impeller of pump 21 reaches R1 in a steady state after the predetermined time has elapsed from time t6.

[0083] Since the water level continues to rise even though the impeller of the pump 21 rotates at the rotation speed R1, the microcomputer 25 switches from control C1 to control C2 at time t7 when the first predetermined time P1 has elapsed since time t6.

[0084] In accordance with control C2, inverter circuit 23 linearly increases the frequency of AC power supplied to motor 22 to frequency F2 over a predetermined time from time t7. The rotation speed of the impeller of pump 21 reaches R2, which is larger than R1, in a steady state after the predetermined time has elapsed from time t7.

[0085] Since the water level continues to rise even when the impeller of the pump 21 rotates at the rotation speed R2, the level of the second signal transitions from the OFF level to the ON level at timing t8 when the water level reaches or exceeds WL2. At timing t8, the microcomputer 25 switches from control C2 to control Cr.

[0086] In accordance with the control Cr, the inverter circuit 23 linearly increases the frequency of the AC power supplied to the motor 22 to the rated frequency Fr over a predetermined time from time t8. The rotation speed of the impeller of the pump 21 reaches Rr, which is larger than R2, in a steady state after the predetermined time has elapsed from time t8.

[0087] As the impeller of the pump 21 rotates at the rotation speed Rr, the water level decreases, and the level of the second signal transitions from the ON level to the OFF level at time t9 when the water level falls below WL2. The level of the first signal transitions from the ON level to the OFF level at time t10 when the water level falls below WL1. The microcomputer 25 ends control Cr at time t10.

[0088] [Example 2] FIG. 6 is a time chart showing another example of changes over time in the level of the first signal, the level of the second signal, the operating frequency, the impeller rotation speed, and the water level according to the first embodiment of the present invention.

[0089] In Example 1 shown in Figure 5, a configuration has been described in which the microcomputer 25 suddenly sets the frequency of the AC power supplied by the inverter circuit 23 to zero at times t2, t5, and t10 when the water level becomes lower than WL1, but this is not limited to this.

[0090] 6, the microcomputer 25 may maintain the operating frequency until a predetermined delay time Td (an example of a "fourth predetermined time") has elapsed from time t2 when the water level becomes lower than WL1, and then linearly reduce the frequency of the AC power supplied by the inverter circuit 23 to zero over a predetermined time. The same applies to times t5 and t10.

[0091] In this way, by continuing operation at the operating frequency from times t2, t5 and t10 when the water level drops below WL1 until the delay time Td has elapsed, operation can be stopped when the water level has dropped sufficiently.

[0092] The delay times Td for the timings t2, t5, and t10 may be the same or different from each other.

[0093] [effect]

[0094] The flow rate of the pump 21 is proportional to the rotation speed of the impeller of the pump 21, i.e., the frequency of the AC power supplied to the motor 22. The power consumption of the motor 22 is proportional to the cube of the rotation speed of the motor 22, i.e., the cube of the frequency of the AC power supplied to the motor 22.

[0095] If the frequency of the AC power supplied to the motor 22 is made lower than the rated frequency Fr, the flow rate of the pump 21 decreases and the time required for draining increases, but the power consumption of the motor 22 is significantly reduced. Therefore, when AC power having a frequency lower than the rated frequency Fr is supplied, the power consumption of the motor 22 is significantly reduced compared to when the motor 22 operates at the rated frequency Fr, thereby achieving a significant energy-saving effect.

[0096] In other words, when the water level rises, instead of immediately rotating the impeller of pump 21 at the rated rotational speed to drain the water, the amount of power consumed can be reduced by rotating the impeller of pump 21 at a rotational speed slower than the rated rotational speed and corresponding to frequency F1 to drain the water.

[0097] On the other hand, if the flow rate of the construction water 211 flowing into the tank 201 is large, the drainage device 11 cannot keep up with the drainage, and the construction water 211 overflows from the tank 201.

[0098] In response to this, the inverter circuit control unit 33 is configured to perform control C1, which causes the inverter circuit 23 to supply AC power of frequency F2, which is higher than frequency F1 and lower than the rated frequency Fr that rotates the motor at the rated rotation speed, when the detection of the first water level state continues for a first predetermined time after starting control C1, thereby reducing the possibility of construction water 211 overflowing from the tank 201 while also reducing power consumption.

[0099] In the present embodiment, the inverter circuit control unit 33 is configured to switch between three frequencies, F1, F2, and F3, to increase the operating frequency before increasing the operating frequency to the rated frequency Fr, but the present invention is not limited to this. The inverter circuit control unit 33 may be configured to switch between two or four or more frequencies to increase the operating frequency before increasing the operating frequency to the rated frequency Fr.

[0100] In addition, in the present embodiment, the configuration has been described in which the discharge target of the drainage device 11 is the construction water 211, but this is not limited thereto. The discharge target of the drainage device 11 may be sewage.

[0101] Second Embodiment A drainage pump control device 101 according to a second embodiment will be described. From the second embodiment onwards, descriptions of matters common to the first embodiment will be omitted, and only differences will be described. In particular, similar actions and effects resulting from similar configurations will not be mentioned in each embodiment.

[0102] The drainage pump control device 101 of the second embodiment differs from the drainage pump control device 101 of the first embodiment in that when a first water level state is detected by the lower water surface detection electrode 26, it is possible to start control to supply AC power of a frequency higher than frequency F1 to the inverter circuit 23.

[0103] 7 is a functional block diagram showing the functions of a microcomputer 125 according to the second embodiment of the present invention. As shown in Fig. 7, the microcomputer 125 further includes a storage unit 35 compared to the microcomputer 25 shown in Fig. 2.

[0104] The storage unit 35 is a volatile storage device that can be read and written, such as a random access memory (RAM). Note that the storage unit 35 may be a non-volatile storage device that can be read and written, such as a flash memory, a hard disk drive (HDD), or a solid state drive (SSD).

[0105] In this embodiment, the storage unit 35 holds a count value i indicating the number of times the timer unit 34 has expired, and information indicating the operation start frequency.

[0106] When the inverter circuit control unit 33 is controlling the supply of AC power to the inverter circuit 23 at a frequency (hereinafter sometimes referred to as the end frequency) that is higher than frequency F1 and lower than the rated frequency Fr (an example of the "fourth frequency"), when the first water level state is no longer detected by the lower water surface detection electrode 26, the inverter circuit control unit 33 stores information indicating the end frequency as the operation start frequency in the memory unit 35 and terminates the control of supplying the AC power to the inverter circuit 23.

[0107] Then, when the first water level state is detected again by the lower water surface detection electrode 26, the inverter circuit control unit 33 starts control to supply AC power at the end frequency to the inverter circuit 23.

[0108] When the first water level state is no longer detected by the lower water surface detection electrode 26 before a third predetermined time has elapsed since the inverter circuit control unit 33 started controlling the supply of AC power at the termination frequency to the inverter circuit 23, the inverter circuit control unit 33 terminates control of supplying the AC power to the inverter circuit 23, and stores in the memory unit 35 information indicating a frequency that is lower than the termination frequency and greater than or equal to frequency F1 (hereinafter sometimes referred to as the deceleration frequency) (an example of the ``fifth frequency'') as the operation start frequency.

[0109] When the detection of the first water level state continues for a third predetermined time after starting control to supply AC power at the end frequency to the inverter circuit 23, the inverter circuit control unit 33 causes the inverter circuit 23 to supply AC power at a frequency (hereinafter sometimes referred to as the acceleration frequency) (an example of the "sixth frequency") that is higher than the end frequency and lower than the rated frequency Fr.

[0110] [Drainage pump control method] Next, a drainage pump control method according to the second embodiment of the present invention will be described in detail. Fig. 8 is a flowchart showing a drainage pump control method executed by a drainage pump control device according to the second embodiment of the present invention. As shown in Fig. 8, the drainage pump control method includes steps S302 to S318, and each step is executed by a processor included in the microcomputer 125.

[0111] In this embodiment, the rotation speed of the motor 22 in the drainage device 11 can be changed in N stages, where N is an integer equal to or greater than 3. The rotation speed increases in the order of the first stage to the Nth stage.

[0112] The motor 22 rotates at a rotation speed that corresponds to the frequency of the AC power supplied to the motor 22 from the inverter circuit 23. That is, the N rotation speed stages correspond to N frequencies, respectively. Specifically, the first, second, and N rotation speed stages correspond to frequency F1, frequency F2, and rated frequency Fr, respectively.

[0113] The time set in the timer unit 34 may be different for each frequency, or may be common to the N frequencies.

[0114] First, the inverter circuit control unit 33 in the drainage pump control device 101 monitors the level of the first signal received from the lower water surface detection electrode 26, and continues monitoring if the level is the off level (NO in step S302).

[0115] Next, when the level of the first signal transitions from the OFF level to the ON level (YES in step S302), the inverter circuit control unit 33 sets the count value i held in the storage unit 35 to zero (step S304).

[0116] Next, the inverter circuit control unit 33 acquires the operation start frequency stored in the storage unit 35 and sets the acquired operation start frequency as the operation frequency (step S306). The operation start frequency stored in the storage unit 35 is updated by a method described later. The default value of the operation start frequency is, for example, frequency F1. In detail, for example, when the main switch is turned off or when the power supply to the drainage pump control device 101 is stopped, the operation start frequency stored in the storage unit 35 is set to the default value.

[0117] Next, the inverter circuit control unit 33 starts controlling the inverter circuit 23 (step S308).

[0118] Next, the inverter circuit control unit 33 performs a control switching process (step S310).

[0119] Next, the inverter circuit control unit 33 ends the control of the inverter circuit 23 (step S312).

[0120] Next, when the count value i held in the memory unit 35 is zero (YES in step S314), the inverter circuit control unit 33 stores in the memory unit 35 the frequency corresponding to the rotation speed of the motor 22 at the stage one stage lower than the stage stage immediately before the end of control as the operation start frequency when the inverter circuit 23 is next controlled (step S318).

[0121] When the frequency corresponding to the rotation speed of the motor 22 immediately before the control is terminated is frequency F1, the inverter circuit control unit 33 may store frequency F1 in the storage unit 35 as the operation start frequency.

[0122] On the other hand, when the count value i stored in the memory unit 35 is 1 or greater (NO in step S314), the inverter circuit control unit 33 stores in the memory unit 35 the frequency corresponding to the rotational speed of the motor 22 at the stage number just before the control ends as the operation start frequency when the inverter circuit 23 is next controlled (step S316).

[0123] Next, the inverter circuit control unit 33 monitors the level of the first signal received from the lower water surface detection electrode 26, and continues monitoring if the level is the off level (NO in step S302).

[0124] 9 is a flowchart showing the control switching process in the drainage pump control device 101 according to the second embodiment of the present invention. FIG. 9 shows details of the operation in step S310 in FIG.

[0125] As shown in FIG. 9, first, the inverter circuit control unit 33 starts control to supply AC power at the set operating frequency to the inverter circuit 23 (step S402).

[0126] Next, the inverter circuit control unit 33 sets a predetermined time corresponding to the operating frequency in the timer unit 34, and activates the timer unit 34 (step S404).

[0127] Next, when the level of the first signal is at the on level and the level of the second signal is at the off level (YES in step S406 and NO in step S408), the inverter circuit control unit 33 monitors the level of the first signal and the level of the second signal until the timer unit 34 expires (NO in step S410).

[0128] Next, when the timer unit 34 expires while the level of the first signal is at the on level and the level of the second signal is at the off level (YES in step S406, NO in step S408, and YES in step S410), the inverter circuit control unit 33 increases the count value i held in the memory unit 35 by one, i.e., increments i (step S412).

[0129] Next, the inverter circuit control unit 33 increases the rotation speed of the motor 22 by one step and controls the inverter circuit 23 to supply AC power having an operating frequency corresponding to the increased rotation speed of the motor 22 (step S414).

[0130] Next, when the operating frequency after the speed increase is lower than the rated frequency Fr (NO in step S416), the inverter circuit control unit 33 sets a predetermined time according to the operating frequency after the speed increase in the timer unit 34 and operates the timer unit 34 (step S404).

[0131] On the other hand, when the operating frequency after the speed increase is the rated frequency Fr (YES in step S416), the inverter circuit control unit 33 continues to control the inverter circuit 23 to supply AC power at the operating frequency after the speed increase while the level of the first signal is at the on level (YES in step S420), and terminates the control switching process when the level of the first signal transitions to the off level (NO in step S420).

[0132] Furthermore, when the level of the first signal transitions to the off level before the timer unit 34 expires (NO in step S406, NO in step S408, and NO in step S410), the inverter circuit control unit 33 ends the control switching process.

[0133] Furthermore, when the level of the second signal transitions to the on level before the timer unit 34 expires (YES in step S406, YES in step S408, and NO in step S410), the inverter circuit control unit 33 switches the operating frequency to the rated frequency Fr and performs control to supply AC power of the rated frequency Fr to the inverter circuit 23 (step S418).

[0134] Next, the inverter circuit control unit 33 continues to control the inverter circuit 23 to supply AC power of the rated frequency Fr while the level of the first signal is at the on level (YES in step S420), and terminates the control switching process when the level of the first signal transitions to the off level (NO in step S420).

[0135] In the above step S316, the frequency corresponding to the rotation speed of the motor 22 at the stage number immediately before the end of the control that has expired at least once by the timer unit 34 is stored in the memory unit 35 as the operation start frequency when the inverter circuit 23 is next controlled.

[0136] With this configuration, the operation start frequency stored in the memory unit 35 can be made closer to the frequency corresponding to the rotation speed of the motor 22 that completes the drainage.

[0137] The level of the first signal transitions to the on level again (YES in step S302), and in step S308 described above, control of supplying AC power at the operation start frequency stored in memory unit 35 to motor 22 is resumed, so that AC power at a frequency higher than frequency F1 can be supplied to motor 22. This makes it possible to shorten the time until drainage is completed compared to when AC power at frequency F1 is always supplied to motor 22 when control of inverter circuit 23 is started.

[0138] In the above step S318, the frequency corresponding to the rotation speed of the motor 22 at the stage one stage lower than the stage stage immediately before the end of the control in which the timer unit 34 has not yet expired is stored in the memory unit 35 as the operation start frequency when the inverter circuit 23 is next controlled.

[0139] If control ends before timer unit 34 has even reached its expiration time, the rotation speed of motor 22 may be excessively high, potentially impairing the reduction in power consumption. With the above configuration, the rotation speed of motor 22 can be reduced by one step when control of inverter circuit 23 is resumed, thereby optimizing the rotation speed of motor 22 and effectively reducing power consumption.

[0140] In the above-described drainage pump control method, the rotation speed of the motor 22 is not increased and operation is resumed at a frequency corresponding to the rotation speed of the motor 22 at a stage one step lower than the stage immediately before the control was terminated only when the level of the first signal transitions to the off level, but this is not limited to this.

[0141] When the inverter circuit control unit 33 is controlling the supply of AC power to the inverter circuit 23 at an end frequency that is higher than frequency F1 and equal to or lower than the rated frequency Fr, and the first water level state is no longer detected by the lower water surface detection electrode 26, the inverter circuit control unit 33 may perform the following process: That is, the inverter circuit control unit 33 stores information indicating the end frequency or a deceleration frequency that is lower than the end frequency and equal to or higher than frequency F1 in the memory unit 35 as the operation start frequency, and terminates the control of the supply of AC power to the inverter circuit 23.

[0142] Then, when the first water level state is detected again by the lower water surface detection electrode 26, the inverter circuit control unit 33 starts control to supply AC power of the deceleration frequency to the inverter circuit 23.

[0143] The following describes a drainage pump control method in which operation is resumed at a frequency corresponding to the rotation speed of the motor 22 at the stage one stage lower than the stage immediately before the end of control.

[0144] 10 is a flowchart showing a modified example of the drainage pump control method executed by the drainage pump control device according to the second embodiment of the present invention. As shown in FIG. 10, the modified example of the drainage pump control method includes steps S502 to S512, and each step is executed by a processor included in the microcomputer 125.

[0145] First, the inverter circuit control unit 33 monitors the level of the first signal received from the lower water surface detection electrode 26, and if the level is the off level, continues monitoring (NO in step S502).

[0146] Next, when the level of the first signal transitions from the off level to the on level (YES in step S502), the inverter circuit control unit 33 acquires the operation start frequency stored in the memory unit 35 and sets the acquired operation start frequency as the operation frequency (step S504).

[0147] The operations in steps S506 and S510 are similar to the operations in steps S308 and S312 shown in FIG. 8, respectively.

[0148] Next, the inverter circuit control unit 33 stores in the memory unit 35 the deceleration frequency corresponding to the rotation speed of the motor 22 at the stage one stage lower than the stage stage immediately before the end of control as the operation start frequency when the inverter circuit 23 is next controlled (step S512).

[0149] When the frequency corresponding to the rotation speed of the motor 22 immediately before the control is terminated is frequency F1, the inverter circuit control unit 33 may store frequency F1 in the storage unit 35 as the operation start frequency.

[0150] Next, the inverter circuit control unit 33 monitors the level of the first signal received from the lower water surface detection electrode 26, and continues monitoring if the level is the off level (NO in step S502).

[0151] 11 is a flowchart showing a modified example of the control switching process in the drainage pump control device 101 according to the second embodiment of the present invention. FIG. 11 shows details of the operation in step S508 in FIG.

[0152] As shown in FIG. 11, the operations in steps S602 to S610 are the same as the operations in steps S302 to S310 shown in FIG.

[0153] Next, when the timer unit 34 expires while the level of the first signal is at the on level and the level of the second signal is at the off level (YES in step S606, NO in step S608, and YES in step S610), the inverter circuit control unit 33 increases the rotation speed of the motor 22 by one step and controls the inverter circuit 23 to supply AC power of an operating frequency corresponding to the increased rotation speed of the motor 22 (step S612).

[0154] The operations in steps S614 to S618 are the same as the operations in steps S416 to S420 shown in FIG.

[0155] In step S512, the frequency corresponding to the rotation speed of the motor 22 at the stage one stage lower than the stage immediately before the control is terminated is stored in the memory unit 35 as the operation start frequency when the inverter circuit 23 is next controlled.

[0156] With this configuration, the operation start frequency stored in the memory unit 35 can be made closer to the frequency corresponding to the rotation speed of the motor 22 that completes the drainage.

[0157] The level of the first signal transitions again to the on level (YES in step S502), and in the above step S506, control of supplying AC power of the operation start frequency stored in memory unit 35 to motor 22 is resumed. This allows the rotation speed of motor 22 to be reduced by one step below the rotation speed before the resumption, thereby optimizing the rotation speed of motor 22 and effectively reducing power consumption.

[0158] Although the inverter circuit control unit 33 has been described as being configured to store the deceleration frequency in the storage unit 35 as the operation start frequency in step S512 above, the present invention is not limited to this. The inverter circuit control unit 33 may be configured to store, in the storage unit 35, the end frequency corresponding to the rotational speed of the motor 22 at the stage immediately before the control is terminated as the operation end frequency. Even with this configuration, when operation is resumed, the inverter circuit control unit 33 can supply, to the inverter circuit 23, AC power at a deceleration frequency corresponding to the rotational speed of the motor 22 at the stage one stage lower than the stage immediately before the control is terminated, based on the end frequency.

[0159] The above-described embodiments are intended to facilitate understanding of the present invention and are not intended to limit the present invention. The elements of the embodiments, as well as their arrangement, materials, conditions, shapes, sizes, etc., are not limited to those illustrated and can be modified as appropriate. Furthermore, configurations shown in different embodiments can be partially substituted or combined with each other. [Explanation of symbols]

[0160] 11...Drainage device, 20...Housing, 21...Pump, 22...Motor, 23...Inverter circuit, 24...DC power generation circuit, 25...Microcomputer, 26...Lower water surface detection electrode, 27...Upper water surface detection electrode, 33...Inverter circuit control unit, 34...Timer unit, 35...Memory unit, 101...Drainage pump control device, 125...Microcomputer, 201...Tank, 201a...Bottom, 211...Construction water, 211a...Water surface

Claims

1. a first sensor that detects a first water level state in which the water level of the water to be discharged is equal to or higher than a first water level; an inverter circuit that supplies AC power to a motor that drives the pump that discharges the water; a control unit that starts control to supply the AC power of a first frequency to the inverter circuit when the first water level state is detected by the first sensor, When the detection of the first water level state continues for a first predetermined time after starting the control, the control unit causes the inverter circuit to supply the AC power of a second frequency that is higher than the first frequency and lower than a rated frequency at which the motor rotates at a rated rotation speed. Drainage pump control device.

2. When the detection of the first water level state continues for a second predetermined time, the control unit controls the inverter circuit to supply the AC power at a third frequency that is higher than the second frequency and lower than the rated frequency. The drainage pump control device according to claim 1 .

3. The drainage pump control device includes: a second sensor for detecting a second water level state in which the water level is equal to or higher than a second water level that is higher than the first water level; the control unit causes the inverter circuit to supply the AC power of the rated frequency when the second water level state is detected by the second sensor. The drainage pump control device according to claim 1 .

4. the control unit terminates control of supplying the AC power to the inverter circuit when the first water level state is no longer detected by the first sensor. The drainage pump control device according to claim 1 .

5. When the first water level state is detected again by the first sensor, the control unit starts control to supply the AC power of the first frequency to the inverter circuit. The drainage pump control device according to claim 4.

6. The drainage pump control device includes: Further comprising a storage unit, The control unit is capable of controlling the inverter circuit to supply AC power of at least one frequency higher than the second frequency and lower than the rated frequency in addition to the second frequency, and when the control unit is controlling the inverter circuit to supply AC power of a fourth frequency higher than the second frequency and lower than the rated frequency, when the first water level state is no longer detected by the first sensor, the control unit stores information indicating the fourth frequency in the storage unit and terminates the control to supply AC power to the inverter circuit. The drainage pump control device according to claim 1 .

7. When the first water level state is detected again by the first sensor, the control unit starts control to supply the AC power of the fourth frequency to the inverter circuit based on the information. The drainage pump control device according to claim 6.

8. When the first water level state is no longer detected by the first sensor before a third predetermined time has elapsed since the control unit started to supply the AC power of the fourth frequency to the inverter circuit, the control unit ends the control to supply the AC power to the inverter circuit and stores information in the storage unit indicating a fifth frequency that is lower than the fourth frequency and equal to or greater than the first frequency. The drainage pump control device according to claim 7.

9. When the detection of the first water level state continues for the third predetermined time after starting control to supply the AC power of the fourth frequency to the inverter circuit, the control unit controls the inverter circuit to supply the AC power of a sixth frequency that is higher than the fourth frequency and equal to or lower than the rated frequency. The drainage pump control device according to claim 8.

10. The drainage pump control device includes: Further comprising a storage unit, The control unit is capable of controlling the inverter circuit to supply AC power of at least one frequency higher than the second frequency and lower than the rated frequency in addition to the second frequency, and when the control unit is controlling the inverter circuit to supply AC power of a fourth frequency higher than the second frequency and lower than the rated frequency, when the first water level state is no longer detected by the first sensor, the control unit stores information indicating the fourth frequency or a fifth frequency lower than the fourth frequency and higher than the first frequency in the storage unit, and terminates the control to supply AC power to the inverter circuit. The drainage pump control device according to claim 1 .

11. When the first water level state is detected again by the first sensor, the control unit starts control to supply the AC power of the fifth frequency to the inverter circuit based on the information. The drainage pump control device according to claim 10.

12. When the first water level state is no longer detected by the first sensor, the control unit terminates control of supplying the AC power to the inverter circuit after a fourth predetermined time has elapsed. The drainage pump control device according to claim 4, 6, 8 or 10.

13. The drainage pump control device according to claim 1 ; the motor; The pump. Drainage equipment.

14. a first sensor that detects a first water level state in which the water level of the water to be discharged is equal to or higher than a first water level; an inverter circuit that supplies AC power to a motor that drives the pump that discharges water, When the first water level state is detected by the first sensor, starting control to supply the AC power of a first frequency to the inverter circuit; and when the detection of the first water level state continues for a first predetermined time after the start of the control, causing the inverter circuit to supply the AC power of a second frequency that is higher than the first frequency and lower than a rated frequency at which the motor rotates at a rated rotation speed. Sump pump control method.

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