JP2002070783A - Backflow detecting system with its detecting method for gate pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a backflow detecting system to remove foreign material from a flap valve at a discharge side by detecting the backflow from the dis charge side during shutdown period of a submersible pump. SOLUTION: In a pump, equipped with a submersible pump in a water shutoff gate 2, provided with a flap valve at discharge side, and forced drainage at closing condition of the water shutoff gate 2, reverse electromotive force generated by the rotation of a rotor 12 or frequency level is detected by the backflow detecting device 18 during the shutdown period of magnetic motor 7 of the submersible pump. This detecting signal is in contrast with the set value of the comparator 19 of control circuit 16 and judged the backflow of the submersible pump and then backflow determination signal is sent to a controller 20 of the control circuit 16. A current circuit 14 connected to the backflow detecting device 18 is switched over the main circuit by the signal of the control controller 20, the magnetic motor 7 is droved at predetermined period and then foreign material in the flap valve is washed out to the discharge side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gate pump in which a submersible pump is mounted on a water stop gate. More specifically, when a submersible pump is stopped, a reverse flow from the discharge side of the submersible pump is detected and the flap valve is engaged. The present invention relates to a backflow detecting method and a backflow detecting system for washing out a foreign substance that has entered.

[0002]

2. Description of the Related Art Conventionally, there is well known a gate pump in which a submersible pump is disposed at a water stop gate which is supported by an irrigation or drainage sluice gate so as to be able to move up and down, and forced drainage is performed in a closed state.
As the gate pump, a vertical shaft type or horizontal axis type submersible pump is used, and a device in which a flap valve is arranged in the submersible pump to prevent backflow of water from the discharge side to the intake side is disclosed in, for example, Patent No. It is publicly known as described in U.S. Pat. No. 2,644,864.

[0003]

A conventional submersible pump provided with a flap valve on the drain side can prevent backflow from the discharge side. However, when the pump stops, a gap is formed in the flap valve. Occurs, and water flows in from the discharge side. When this backflow phenomenon occurs, inundation occurs in the upstream region, and if the downstream region is seawater, salt damage occurs in the upstream region.
To prevent this, there is a method of installing an on-off valve inside the gate to prevent backflow.This method not only increases the weight of the gate-integrated pump, but also opens the inside of the pump during natural flow. Since it flows down, there is a point that it is difficult to open and close the on-off valve at the time of backflow.
In addition, there is a method in which a position detector such as an encoder is mounted on the motor body to detect the rotation direction of the motor shaft, and the pump is operated at the time of reverse rotation, that is, at the time of reverse flow. However, there are problems such as an increase in size, an increase in the number of wirings for position detection, and accuracy due to dew condensation of the position detector in the underwater sealed portion inside the motor. In addition, the backflow is detected by measuring the inside and outside water levels and the flow velocity in the channel,
The method of operating the submersible pump involves problems such as an increase in cost, such as the location and wiring of the current meter and maintenance over time. SUMMARY OF THE INVENTION An object of the present invention is to provide a method and a system for detecting a backflow phenomenon in a gate pump that removes a flow-down substance caught in a flap valve on a discharge side of a gate pump and prevents a backflow to an upstream side. .

[0004]

In order to achieve the above object, a submersible pump is arranged at a water stop gate supported so as to be able to move up and down, and a flap valve is provided on the drain side of the submersible pump, so that the water stop gate is provided. In a pump that performs forced drainage in a closed state, a control circuit is provided between the submersible pump and a power supply device,
This control circuit is equipped with an electromagnetic contactor that supplies power to the drive unit of the submersible pump, and a backflow detector that detects the backflow of the submersible pump.When the submersible pump is stopped, connect the backflow detector to the power supply unit. When the backflow detection device detects backflow from the discharge side to the submersible pump, it activates a timer based on the detection signal and connects the current circuit to the motor of the submersible pump,
This is a method for detecting a backflow in a gate pump in which a submersible pump is driven for a predetermined period of time to flush foreign substances caught in the flap valve to the drainage side. Specifically, this backflow detection method uses the motor of the submersible pump as a motor with a built-in magnet, and when the motor with a built-in magnet is stopped, the back electromotive force generated in the stator winding by the permanent magnet due to the rotation of the built-in permanent magnet of the rotor. Alternatively, there is a backflow detection method in which the level of the frequency is detected by a backflow detection device, and the backflow is determined by a submersible pump that is rotated by the backflow water.

A system for implementing the above-described method for detecting a backflow phenomenon of a gate pump includes a control circuit provided between a submersible pump and a power supply device, an electromagnetic contactor for supplying power to the submersible pump, and a submersible pump. A backflow detection device that detects the backflow of the pump is provided side by side, and the motor of the submersible pump is a motor with a built-in magnet, and when the motor with a built-in magnet is stopped,
The back electromotive voltage or frequency level generated in the stator winding by the permanent magnet due to the rotation of the rotor built-in permanent magnet is detected by a backflow detecting device, and this detection signal is detected at a preset frequency level or back electromotive voltage. The phase sequence is compared with the comparator of the control circuit to determine the backflow of the submersible pump, and a backflow determination signal of the comparator is transmitted to the controller of the control circuit, and is connected to the backflow detection device by the command signal of the controller. The current circuit is switched to the main power system, and the motor with a built-in magnet is driven for a predetermined period of time to flush foreign substances caught in the flap valve to the drainage side, or the current circuit connected to the backflow detection system The current circuit connected to the backflow detecting device may be connected to the alarm device by switching to the system.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The detection system for a backflow phenomenon of a gate pump according to the present invention is configured as described above. When the submersible pump is stopped, the electromagnetic contactor is disconnected from the main power system, and the backflow detection device is powered. Connect to the device. When foreign matter is caught in the flap valve and backflow water flows into the pump from the drain side, the impeller mounted on the pump rotates in the reverse direction. The rotation of the impeller rotates the permanent magnet with a built-in rotor of the motor with a built-in magnet, and the backflow detection device detects the level of the back electromotive voltage or frequency generated in the stator winding. This backflow detection system performs backflow determination by measuring the level of the back electromotive voltage or frequency and examining the phase sequence of the back electromotive voltage as a detection result. The controller transmits a backflow determination signal to the controller of the control circuit, and switches the current circuit connected to the backflow detection system to the main power system by a command signal of the controller to drive the motor with a built-in magnet for a predetermined time, The foreign matter caught in the flap valve is flushed to the drain side. Alternatively, the current circuit connected to the backflow detection system may be switched to the main power system, and the current circuit connected to the backflow detection system may be connected to the alarm device.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail with reference to the accompanying drawings. First, FIG. 1 is a conceptual diagram of a gate pump. A horizontal shaft type submersible pump 3 is supported on the water stop gate 2. FIG. 2 is a longitudinal sectional side view of the submersible pump 3, in which an impeller 5 is disposed inside a blade casing 4, and an impeller boss 6 to which the impeller 5 is fixed is connected to a motor 7 with a built-in magnet. It is. The motor 7 with a built-in magnet is supported by guide blades 9 fixed to a discharge casing 8 connected to the rear end of the blade casing 4. The suction port 4a of the blade casing 4 and the discharge port 8a of the discharge casing 8 are disposed in the axial direction, and the discharge port 8a of the discharge casing 8 is connected to a discharge pipe 22 penetrating the inside of the water stop gate 2. . In the submersible pump 3, since the flow direction in the pump is parallel to the flow of the river, when water flows into the pump, the impeller 5 of the submersible pump 3 rotates freely under natural flow. When the external water level a on the drain side is higher than the internal water level b on the water collecting side, the impeller 5 of the submersible pump rotates in reverse by the backflow water. In addition, even in the vertical shaft type submersible pump, the impeller freely rotates under natural flow, and the impeller rotates reversely by the backflow water. The submersible pump supported on the water stop gate 2 is a vertical shaft type submersible pump. Is also good. A flap valve 10 is pivotally connected to the discharge side of the discharge pipe 22 connected to the discharge casing 8 so that the outer water level a on the discharge side becomes higher than the inner water level b on the water collection side. The discharge pipe 22 is closed by the flap valve 10 to prevent backflow from the discharge side.

FIG. 3 shows the principle of the motor 7 with a built-in magnet. The motor 7 with a built-in magnet has a stator winding 11 provided with three-phase windings, and a permanent magnet with a built-in rotor inside the stator winding 11. 1
When a rotating magnetic field generated by a three-phase winding is generated in the stator winding 11, the magnetic poles are attracted and the rotor built-in permanent magnet 12 rotates to rotate the impeller 5. ing. Then, the electromotive voltages U, V, and W at the terminals of the three-phase winding of the stator winding 11 can be measured. As shown in FIG. 1, a submersible pump 3 and a three-phase power supply 1
3 is connected by a current circuit 14 so as to supply electric power to the motor 7 with a built-in magnet.
Between 3, a control panel 15 is provided. The control panel 15 will be described in detail with reference to FIG. 4. The control panel 15 is provided with a control circuit 16.
An electromagnetic contactor 17 that operates to supply and stop electric power to the motor 7 with a built-in magnet, and a backflow detection device 18 that detects the rotation of the impeller 5 of the submersible pump 3 are provided side by side. When the motor 7 with built-in magnet is stopped, the backflow detecting device 18 is connected to the terminal of the stator winding 11 so that the electromotive voltages U, V, and W generated by the three-phase windings have the voltage phases at the time of natural flow and the voltage phases at the time of reverse flow. The voltage phase is detected. The control circuit 16 includes a comparator 19 for comparing the level of the frequency determined to be a backflow or the back electromotive voltage with a preset numerical value and the level of the back electromotive voltage or the frequency detected by the backflow detecting device 18, and a flap valve. 10
When it is determined that the backflow water flows into the submersible pump 3 from the drainage side and the impeller 5 is rotating in the reverse direction, the electromagnetic contactor 1 to the magnet built-in motor 7 of the submersible pump 3
7, a controller 20 for driving the submersible pump 3 for a predetermined time is provided. Reference numeral 21 denotes an earth leakage breaker.

The operation procedure of the backflow detection system will be described with reference to the flowchart of FIG. 5. When the submersible pump 3 is stopped with the water stop gate closed, that is, at the time of natural flow, the electromagnetic contactor 17 is connected to the main power system. Disconnect from the circuit 14 and connect the backflow detector 18 to the three-phase power supply 13.
The backflow detecting device 18 detects the presence or absence of the back electromotive voltage or frequency due to the flow, and compares the level of the preset frequency or the back electromotive voltage, and if the detection signal becomes NO, the flap valve 10 is caught by the foreign material. Judge that there is no
Feed back to the previous stage. If the counter electromotive voltage due to the flow or the frequency is detected and the result is YES, the level is compared with the level of the preset frequency or the counter electromotive voltage,
When the phase sequence of the voltage is lower than the phase sequence of the backflow voltage, it is determined that the amount of water flowing into the submersible pump is small, and feedback is performed to the preceding stage. When the phase sequence of the voltage exceeds the phase sequence of the backflow voltage, it is determined that foreign matter has caught in the flap valve 10 and backflow water has flowed into the submersible pump 3 from the drainage side, and the connection to the backflow detection device 18 has been made. The switched current circuit 14 is switched to the main power system and connected to the alarm device. Next, the current circuit 14 connected to the backflow detecting device 18 is switched to the main power system, and the motor 7 with a built-in magnet is driven for a predetermined time to flush the foreign matter caught in the flap valve 10 to the drainage side. Feedback when the submersible pump 3 stops. When the trapping of foreign matter by the flap valve 10 is not eliminated, the submersible pump 3 is driven again.

[0010]

The present invention is constructed as described above, and when the submersible pump is stopped, the back electromotive voltage or the frequency level at which the stator winding generates due to the rotation of the rotor built-in permanent magnet of the magnet built-in motor. Is detected by the backflow detecting device, so that the backflow from the discharge side of the submersible pump can be detected, and the foreign matter caught in the flap valve can be washed away.
That is, the gate pump of the conventional device provided with the on-off valve has a disadvantage that it is difficult to adjust the on-off valve at the time of backflow. Also,
The method of mounting a position detector such as an encoder to detect the rotation direction of the motor shaft requires a large pump body, and has problems such as accuracy due to dew condensation of the position detector in a sealed portion underwater inside the motor. Further, the method of detecting the backflow by measuring the inside and outside water levels and the flow velocity in the water channel has a problem that costs are high, such as a place where the current meter is installed, wiring, and maintenance over time. According to the present invention, when the submersible pump is stopped, the back electromotive voltage or frequency level generated by the rotor built-in permanent magnet of the magnet built-in motor is detected by the back flow detecting device, and this detection signal is detected at a predetermined frequency. The control circuit determines the level or the phase sequence of the back electromotive voltage, switches the current circuit connected to the backflow detection system to the main power system, drives the submersible pump for a predetermined time, and removes foreign matter that has caught in the flap valve. It is flushed to the drainage side and can prevent backflow to the upstream side. The back electromotive voltage can be detected by measuring the instruments in the control panel, and back flow can be detected. A separately installed detector is unnecessary, and the back electromotive voltage can be detected without being affected by the surrounding environment.
In addition, since the rotation of the impeller is used, the backflow can be quickly detected.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a backflow detection system in a gate pump according to the present invention.

FIG. 2 is a vertical sectional side view of a submersible pump provided with a main part built-in motor according to the present invention.

FIG. 3 is a diagram showing the principle of rotation of a motor with a built-in magnet.

FIG. 4 is a wiring diagram of a control panel.

FIG. 5 is a flowchart of the backflow detection system.

[Explanation of symbols]

 2 Water stop gate 3 Submersible pump 7 Motor with built-in magnet 10 Flap valve 12 Permanent magnet with built-in rotor 13 Three-phase power supply 14 Current circuit 16 Control circuit 17 Magnetic contactor 18 Backflow detector 19 Comparator 20 Controller

Claims (5)

[Claims] 1. A submersible pump (3) is arranged at a water stop gate (2) that can be raised and lowered, and a flap valve (10) is provided at a drain side of the submersible pump (3). In a pump for forcibly draining water in a closed state, a control circuit (16) is provided between the submersible pump (3) and a power supply (13), and the control circuit (16) includes a drive unit (7) for the submersible pump (3). ), And a backflow detecting device (18) for detecting the backflow of the submersible pump (3). When the submersible pump (3) is stopped, the backflow detecting device (18) is provided. ) Is connected to a power supply device (13), and when the backflow detecting device (18) detects a backflow from the discharge side to the submersible pump (3), the detection signal sends a current to the electric motor (7) of the submersible pump (3). The circuit (14) is connected, the submersible pump (3) is driven for a predetermined time, and the A method for detecting a backflow in a gate pump, comprising washing foreign matter caught in the lap valve (10) to a drainage side. 2. The motor of the submersible pump (3) is a motor with a built-in magnet (7), and when the motor with a built-in magnet (7) is stopped, the back electromotive voltage or frequency generated by the permanent magnet (12) with a built-in rotor. 2. The method according to claim 1, wherein the reverse flow is detected by a reverse flow detecting device, and the reverse flow is determined by a submersible pump rotating by the reverse flow water. 3. A submersible pump (3) is arranged at a water stop gate (2) that can be raised and lowered, and a flap valve (10) is provided at a drain side of the submersible pump (3). In a pump that performs forced drainage in a closed state, a control circuit (16) is provided between the submersible pump (3) and a power supply (13), and power is supplied to the submersible pump (3) to the control circuit (16). An electromagnetic contactor (17) and a backflow detecting device (18) for detecting the backflow of the submersible pump (3) are arranged side by side, and the motor of the submersible pump (3) is a motor with a built-in magnet (7), and the built-in magnet is When the motor (7) is stopped, the back electromotive voltage or frequency level generated in the stator winding (11) by the rotation of the rotor built-in permanent magnet (12) is detected by the backflow detection device (18). , This detection signal is set to a preset frequency level Alternatively, a backflow detection system in a gate pump, wherein the backflow of the submersible pump (3) is determined by comparing the phase sequence of the back electromotive voltage with the comparator (19) of the control circuit (16). 4. A backflow judging signal of the comparator (19) is transmitted to a controller (20), and a current circuit (1) connected to a backflow detecting device (18) is transmitted by a command signal of the controller (20).
4. The gate pump according to claim 3, wherein the step (4) is switched to a main power system, and the motor with a built-in magnet (7) is driven for a predetermined period of time to flush foreign substances caught in the flap valve (10) to a drain side. Backflow detection system. 5. The system according to claim 3, wherein the current circuit (14) connected to the backflow detecting device (18) is connected to an alarm device.