JP3314224B2 - underwater pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a submersible pump used for drainage in civil engineering works, and more particularly to a pump main body which detects a water level by a capacitance type water level detection sensor and responds to the detection signal. The present invention relates to a submersible pump whose operation is controlled.

[0002]

2. Description of the Related Art A submersible pump used for drainage in civil engineering works automatically starts a draining operation when water to be drained (hereinafter referred to as "reserved water") reaches a certain level, and the water level is reduced by the drainage. It is necessary to automatically stop the draining operation when the water level decreases. For this reason, in such a submersible pump, a sensor for detecting a water level and the pump main body are configured to cooperate. There are various types of such water level detection sensors. Among them, a capacitance type sensor is particularly useful because it is not affected by oil in the storage water. As a conventional example of such a capacitance type sensor, for example, Japanese Utility Model Publication No. Sho 63-36246
And Japanese Utility Model Publication No. 47-11638. The latter (Japanese Utility Model Publication No. 47-11638) discloses a configuration in which such a sensor and a pump body are integrated.

FIG. 6A is a diagram schematically showing a principle of detecting a water level in a conventional submersible pump using such a capacitance type sensor, and a non-constituting electrode constituting both electrodes of the capacitance of the sensor. A ground electrode 101 and a ground electrode 102 (reference potential electrode) are attached to the outer surface of the pump, and the surface is waterproof-coated with an insulating layer 103 such as rubber. In this sensor, when the water level rises to a position above the non-grounded electrode 101 and the electrodes 101 and 102 both face the stored water W, the dielectric constant of water is larger than the dielectric constant of air, so that the electrodes 101 and 102 The capacitance between them increases. The change in the capacitance is converted into a change in an electric signal, and the motor of the pump body is turned on based on the change.
To When the water level drops, the motor of the pump body is turned off by the reverse operation. In addition,
A dashed line E in this figure indicates a line of electric force between the two electrodes.

There is also a facing-type electrode arrangement as shown in FIG. 6 (b), in which electrodes 101 and 102 covered with insulating layers 103a and 103b, respectively, are opposed to each other. The principle of water level detection and pump control in this case is shown in FIG.
This is the same as the case (a).

[0005]

In the conventional submersible pump, since the capacitance type water level detecting sensor has such a structure, the electric line of force E between the electrodes 101 and 102 is insulated twice. Pass through the layers. That is, FIG.
In the case of (a), once before the electric line of force E enters the reservoir water W from the non-ground electrode 101, and once after the electric line of force E returns from the reservoir water W to the ground electrode 102. Two times in total. In the case of FIG. 6B, this corresponds to the case where the electric lines of force E pass through the insulating layers 103a and 103b once. Therefore, in each case, these electrodes 10
The insulating layer 103 (10
3a, 103b), the change in capacitance value due to the water level of the storage water W becomes relatively small. As a result, in such a technique, there is a problem that the detection accuracy of the water level is low.

Further, in order to cope with such a situation where the sensitivity is low, it is conceivable to improve the gain when converting a change in capacitance value into an electric signal. However, in this case, not only the circuit configuration becomes complicated, but also noise and the like are amplified, so that there is a problem that erroneous detection is likely to occur.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to overcome the above-mentioned problems in the prior art, and to perform a reliable water level detection with a relatively simple configuration, thereby accurately controlling an operation based on a water level change. It is an object of the present invention to provide a submersible pump.

[0008]

In the present invention, attention is paid to the fact that the stored water in the drainage of civil engineering works itself is in contact with the ground at the bottom. That is, in such a case, since the ground functions as a ground electrode, if it is used, the ground electrode need not be provided on the sensor side.

In order to use the ground as a ground electrode, it is necessary to electrically connect the ground side of the sensor to the ground. This can be achieved by routing the ground wire of the sensor and connecting it to the ground around the drainage site.However, performing ground wiring at a construction site is not only troublesome, but also causes detection errors due to poor grounding. There is also the possibility of inviting.
Therefore, in the present invention, attention is paid to the fact that a commercial power line or the like for obtaining the operating power of the pump body includes a ground line, and the electric grounding of the capacitance for detecting the water level in the sensor is performed by the power supply of the pump body. Achieved by connecting to the wire side.

Therefore, it is not necessary to provide a portion corresponding to the ground electrode among the electrodes forming the capacitance in detecting the water level, and it is also necessary to provide an insulation for electrically insulating the ground electrode from the stored water. A coating layer is not required, and a decrease in sensitivity due to the presence of such an insulating coating layer can be prevented.

On the other hand, in such grounding improvement, if the sensor and the pump body are spatially separated, the wiring for connecting the grounding level of the sensor to the power supply line becomes long. Therefore, in the present invention, a sensor is attached to the pump main body, and the ground connection of the sensor to the power supply line side of the pump main body as described above is performed. This eliminates the need for a separate long wiring for the ground connection of the sensor, simplifies the configuration, and prevents a reduction in reliability due to the long wiring.

[0012]

【Example】

<1. FIG. 1 is a schematic external view of a submersible pump 1 for drainage according to an embodiment of the present invention. The submersible pump 1 is roughly divided into a pump main body 10 and a sensor section 20, and the pump main body 10 is provided with the sensor section 20 and integrated therewith. The pump body 10 accommodates a pump 12 in a main casing 11, and when the submersible pump 1 is disposed in water to perform a draining operation, the pump body 10 sucks stored water from the lower part of the pump body 10 as indicated by an arrow IN. Water is drained from the drain port 13 as indicated by an arrow OUT. A hose (not shown) is connected to the drain 13, and the hose extends to the drain.

On the other hand, the sensor section 20 is a section including a capacitance type water level sensor. In this sensor, a non-grounded electrode (detection electrode) 22 of a capacitor which should produce a change in capacitance according to the water level is formed by a casing 21. Is provided on the outer surface of the device and faces the outside. This ungrounded electrode 22 corresponds to the sensor head of this sensor. A control circuit 30, which will be described in detail later with reference to FIG. The sub-casing 21 is covered with an insulating layer 23 of rubber or the like for waterproofing and electrical insulation, and this covering also covers the surface of the non-grounded electrode 22. Also,
A power cable 50 connected to a commercial power line or the like enters from above, passes through the sensor unit 20, and is connected to a motor in the pump body 10.

<2. Electrical Configuration of the Embodiment> FIG. 2 is a circuit diagram showing an electrical configuration around a control circuit 30 built in the sensor section 20 of FIG. The control circuit 30 is roughly divided into a power supply circuit PC and a sensor control circuit SC. First, in the power supply circuit PC, the power supply cable 50 described with reference to FIG.
1,52, and a power supply circuit P
A rectifying step-down circuit 38 in C and a series circuit of capacitors C4 and C5 are connected in parallel. The rectifying step-down circuit 38 includes a transformer, a diode, and the like, and generates and supplies DC operation power to circuit elements such as an inverting amplifier 32 and a flip-flop 33, which will be described later. The wiring to is omitted.) The selection of the capacitance values of these capacitors C4 and C5 will be described later.

One of the power supply lines 51, 52
Is also connected to the pump 12 via a triac 37. A phototriac 36 is connected between one main electrode of the triac 37 and the control electrode via a resistor R5 for ON / OFF control of the triac 37. The pump 12 is connected to the power supply line 51 (A-phase power supply line) via the triac 37 as described above, and is also connected to the other power supply line 52 (B-phase power supply line). Therefore, when the triac 37 is ignited by the operation described later, AC power from these power supply lines 51 and 52 flows through the pump 12, and the motor in the pump 12 starts rotating. When the triac 37 is extinguished, the rotation of the motor stops.

On the other hand, an oscillation circuit 31 including a CMOS inverting amplifier 32 having a Schmitt trigger function and a feedback resistor R1 is provided at the first stage (left side in FIG. 2) of the sensor control circuit SC. The oscillation circuit 31 generates a repetitive pulse at a period determined by the circuit constants of these components. In addition,
This oscillation circuit 31 is connected to a ground line GL via a capacitor C1.
Connected to the wire.

The output of the oscillation circuit 31 is input to two delay circuits in parallel. The first delay circuit includes a resistor R2
Variable delay circuit VDy constituted by a combination of a resistor R3 and a capacitor C3. An RC fixed delay circuit CD constituted by a combination of a resistor R3 and a capacitor C3.
y.

The equivalent capacitor C2 of the RC variable delay circuit VDy is a capacitor formed between the ungrounded electrode 22 described with reference to FIG. 1 and the ground at the drainage site (the ground at the bottom of the storage water) GND. The output is the data input D of the flip-flop 33 of FIG. However, the ground GND at the drainage site is not provided with a ground line, but the ground GND is at the ground level in a natural state. This is because the stored water W is physically in contact with the ground GND. The ground line GL is connected to the power lines 51 and 52 via the capacitors C4 and C5 according to the characteristics of the present invention. One of these power lines 51 and 52 is a commercial power generation facility (or substation facility) 40. (Ground 41 in FIG. 2). This ground 41 is at the same potential as the ground GND at the bottom of the stored water through the ground. Therefore, the ground line GL has the same potential as the ground GND via the power supply line 51 or 52, and the ground GND functions as a ground electrode of the equivalent capacitor C2 in the sensor control circuit SC. Therefore, only the non-ground electrode 22 needs to be provided for the equivalent capacitor C2 from the actual device configuration, and the ground electrode need not be provided on the sensor side. The capacitor C2 is called an "equivalent" capacitor because the device does not have a pair of electrodes like a normal capacitor, but functions equivalently as a capacitor when considering the ground GND.

Generally, the delay time of an RC delay circuit is proportional to the product of the capacitance value and the resistance value.
The delay time of the variable delay circuit VDy is also proportional to the product: “C2 × R2”. Further, when the level of the stored water rises, the surface of the stored water approaches the non-grounded electrode 22, which is equivalent to an increase in the ground-side electrode area of the equivalent capacitor C 2,
Thereby, the capacitance value of the equivalent capacitor C2 increases. Therefore, when the water level rises, the RC variable delay circuit VDy
Is longer. Conversely, when the water level decreases, the capacitance value of the equivalent capacitor C2 decreases, and the delay time of the RC variable delay circuit VDy decreases.

On the other hand, in RC fixed delay circuit CDy, resistor R3 and capacitor C3 are fixed, and therefore, the delay time is also fixed. The output after receiving the fixed delay is the clock input CK (sampling timing input) of the flip-flop 33.

The flip-flop 33 functions as a phase comparator or a phase discriminator.
An output Q corresponding to the result is generated by comparing the phase with K. Although an example of this phase comparison operation will be described later, the output Q thus obtained is connected to the ground level line GL via a series connection of the inverting amplifier 34, the phototriac 35 and the resistor R4.

<3. Operation of Embodiment> The water level detection and pump control by such a configuration will be described below with reference to FIG. 3 which is a timing chart of the sensor control circuit SC and FIG. 4 showing the water level and the pump 1. Become like

<3-1. When the water level is low>
When the water level is low as illustrated in FIG. 3A, the capacitance value of the equivalent capacitor C2 is small, so that the delay time T1 in the RC variable delay circuit VDy is R as illustrated in FIG.
This is shorter than the delay time T2 in the C fixed delay circuit CDy. However, these delay times are based on the rising time t0 of the oscillation pulse (not shown) of the oscillator 31. When there is a relationship of T1 <T2, FIG.
As shown in (a), the data input D of the flip-flop 33 rises to "H (High Level)" before the clock CK. Then, the flip-flop 33 outputs the clock CK
When the data input D is sampled at the rising point t of the data, the data input D is already "H" and the output Q
Becomes "H" and is latched at this "H" level. This has the same result as long as the water level remains low. This output Q (= “H”) is amplified and inverted by the inverting amplifier 34 in FIG. 2 to become “L (Low Level)”. For this reason, the photo triac 35 is OFF and does not emit light, the triac 37 is also OFF, and the pump 12 is stopped.

<3-2. When the water level is high> On the other hand, FIG.
When the water level rises as illustrated in FIG. 3B, the capacitance value of the equivalent capacitor C2 is large. Therefore, as illustrated in FIG. 3B, the delay time T1 in the RC variable delay circuit VDy is changed to the RC fixed delay circuit CDy. , The data input D of the flip-flop 33 rises to “H” after the clock CK. For this reason, the flip-flop 33 operates at the rising time t of the clock CK.
Data input D is still "L"
And the output Q is latched at “L”. This has the same effect as long as the water level remains high. This output Q (=
“L”) is amplified and inverted by the inverting amplifier 34 to become “H”. For this reason, the photo triac 35 is turned on,
The triac 37 is turned on in response to the light emission. In response, the pump 12 is activated and drains.

<4. By the way, as described above, in this embodiment, the sensor control circuit SC (therefore, equivalent capacitor C2) corresponds to the feature of the present invention.
Is connected to power supply lines 51 and 52 via capacitors C4 and C5. These capacitors C4,
The capacitance value of C5 is equal to the high frequency (oscillation circuit 31) generated by the sensor control circuit SC while electrically separating the sensor control circuit SC from the power lines 51 and 52 with respect to the commercial frequency from the power lines 51 and 52. (The oscillation pulse frequency) is selected so as to be in a conductive state so that the connection by ground is electrically effective.

More specifically, the capacitance of the capacitors C4 and C5 has a sufficiently large impedance with respect to the alternating current of the commercial power frequency (50 Hz or 60 Hz), and has a sufficiently small impedance with respect to the capacitance of the equivalent capacitor C2. Will be selected. In this embodiment, C4 and C5 = 1000 pF. In this case, the impedance becomes about 3 MΩ for a commercial power supply frequency of 60 Hz, for example, and the leakage current is about 70 μA or less. Therefore, there is no problem in terms of safety and power saving. Further, since the equivalent impedance C2 is usually several tens of pF, the impedance is sufficiently small.

The reason why the ground line GL is connected to both of the two power lines 51 and 52 via the capacitors C4 and C5 is that the power lines 51 and 52 are connected to a commercial power supply in an outlet form. , And which of the power supply lines 51 and 52 is on the ground side of the commercial power supply, is different. Therefore, in principle, it may be connected to the ground side of the plurality of power supply lines. For example, in the case of a pump that is provided with a switchboard that converts commercial power to DC through an AC / DC converter, and that drives a DC motor by taking DC power from the switchboard,
Since the ground side of the power supply line is clear, the ground line of the sensor control circuit may be connected only to the ground side.

On the other hand, regarding the determination of the capacitance value of the fixed-side capacitor C3 in relation to the equivalent capacitor C2, when the water level is around the non-grounded electrode 22 as shown in FIG. It is preferable that the capacitance value of the fixed-side capacitor C3 is determined in advance so that the point time is inverted. This can easily be determined by experiment. Strictly speaking, the components of the stored water W differ depending on the place where the pump is used. However, the fluctuation range of the conductivity is not as large as the difference between the conductivity of the water and the air. There is no need to adjust each time.

<5. Sensitivity and Wiring of Sensor of Example> FIG.
FIG. 3 is an explanatory diagram relating to the sensitivity of a water level detection sensor in the submersible pump 1 of the embodiment. As explained in FIG.
Since the ungrounded electrode 22 in FIG. 5 is covered with an insulating layer 23 such as rubber, the lines of electric force E from the ungrounded electrode 22 reach the stored water W via the insulating layer 23. The lines of electric force E equivalently reach the ground (ground at the bottom of the storage water) GND corresponding to the ground electrode, but do not pass through an insulating layer of rubber or the like when reaching the ground. That is,
In the case of the related art described with reference to FIG. 6, the insulating layer passes through the insulating layer twice, but in the case of this embodiment, only once.

Therefore, the equivalent capacitor C2 shown in FIG.
2 is relatively large. Therefore, the output sensitivity of the sensor is large with respect to a change in water level, and a complicated high-gain circuit is not required. Also, the noise resistance is high. Therefore, control of the pump as a whole is accurate.

In this embodiment, the sensor unit 20 shown in FIG.
Is attached to the pump body 10 and integrated, so that it is possible to connect to the power supply lines 51 and 52 without taking the ground wiring GL long. This is not only advantageous in terms of wiring, but also
Reliability has also increased.

<6. Modification> If the sensor section 20 is provided outside the pump body 10 as in the above embodiment, the pump of the present invention can be realized by adding the sensor section 20 to a pump having no sensor. There are advantages. However, it is also possible to house the pump body and the sensor unit in a single casing, and the “attachment” in the present invention includes such a case.

In the above embodiment, the sensor control circuit 30
Although the ground line GL has been described as a line, it may be a connection point (node) on a printed circuit board or the like.

In the above embodiment, the resistor R3 is a fixed resistor and the capacitor C3 is a fixed capacitor. However, if the adjustment switch is added using a variable resistor or a variable capacitor, the ON / OFF of the pump can be changed. A function for changing the water level for switching OFF can also be provided.

The pump of the present invention can be used not only for drainage at a construction site, but also for any purpose as long as drainage of stored water is in a state where there is no electrical insulation between the pump and the ground.

[0036]

As described above, according to the present invention, the ground level of the water level detecting capacitance of the sensor is changed to the power line side in accordance with the fact that the stored water is electrically grounded at the bottom. Achieved by connecting to.

For this reason, it is not necessary to provide a portion corresponding to the ground electrode among the electrodes forming the capacitance of the sensor. In addition, an insulating coating layer for electrically insulating the ground electrode from water is provided. And the sensitivity can be prevented from lowering due to the presence of such an insulating coating layer.

Further, since the sensor is attached to the pump body, a long wiring is not required to connect the ground level of the water level detection capacitance to the power supply line.

Therefore, the water level can be reliably detected with a relatively simple configuration, and the operation control based on the water level change can be accurately performed.

[Brief description of the drawings]

FIG. 1 is a schematic external view of a submersible pump according to an embodiment of the present invention.

FIG. 2 is a circuit diagram of a control circuit of the submersible pump according to the embodiment.

FIG. 3 is a waveform chart showing an example of a phase comparison operation in the control circuit of FIG. 2;

FIG. 4 is an explanatory diagram of a state of a water level in the submersible pump according to the embodiment.

FIG. 5 is an explanatory diagram of sensor sensitivity in the submersible pump according to the embodiment.

FIG. 6 is a conceptual explanatory view of a sensor used in a conventional submersible pump.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Submersible pump 10 Pump main body 11 Main casing 12 Pump 20 Sensor part 21 Sub-casing 22 Non-ground electrode 23 Insulating coating 30 Control circuit 31 Oscillation circuit 40 Commercial AC power supply 41 Grounding of commercial AC power supply 50 Power supply cable 51, 52 Power line C2 Equivalent capacitor PC Power circuit SC Sensor control circuit GL Ground line of sensor control circuit W Reservoir GND GND Ground of the bottom of the reservoir

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-3-249395 (JP, A) JP-A-54-41768 (JP, A) JP-A-61-233323 (JP, A) JP-A-54-41 104872 (JP, A) Fully open Showa 47-11638 (JP, U) Fully open show 63-36246 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F04D 13/08 F04D 15 / 00 G01F 23/26

Claims (1)

(57) [Claims] 1. A submersible pump in which operation control is performed in response to a detection signal from a capacitance type water level detection sensor, wherein the sensor is attached to a pump body, and a capacitance of the sensor for detecting a water level in the sensor is provided. A submersible pump, wherein electrical grounding is achieved by connecting the pump body to a power line side.