JP3229216U - Flow sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flow sensor capable of confirming whether water is surely flowing in a distribution path by a method that is inexpensive, has no mechanical moving parts, and is easy to maintain. SOLUTION: Two rod-shaped metal detection electrodes (detection electrode anode 2a, detection electrode cathode 2b) and a water temperature sensor are attached to an electrode fixing substrate to detect whether water is flowing in a water distribution path. Therefore, a metal detection electrode (anode 2a, cathode 2b) and a temperature correction water temperature sensor 1 are inserted into the water distribution path. The anode 2a is energized, the charging time of the capacitor 4 connected to the cathode 2b side is measured by the increment counter 9, and the measured time value is measured by the temperature correction unit 11 after the temperature correction by the temperature correction unit 11, and the flow velocity calculation unit 12 is based on the difference over time. The flow velocity is obtained with, and the water flow determination unit 13 determines whether or not water is flowing. [Selection diagram] Fig. 1

Description

The present invention is for constantly confirming whether or not the water supply device reliably supplies water to the distribution route.

Conventionally, ultrasonic type, impeller type, electromagnetic induction type, Karman vortex type, and other flowmeters, paddle type, and area type flow switches have been used to check the flow of water distribution paths. Impeller-type and Karman vortex-type flowmeters and paddle-type and area-type flow switches have structures that are larger than the cross-sectional area of the water distribution path, so malfunctions due to dust clogging are likely to occur. The ultrasonic flowmeter is simple because the transmitter and receiver are attached without cutting the distribution path, and there is no concern about malfunction due to dust clogging in the distribution path, but installation space is required to some extent for the diameter of the distribution path. Therefore, it is not compact. Since the electromagnetic induction type flowmeter has a structure that is relatively small with respect to the cross-sectional area of the water distribution path, malfunctions due to clogging with dust are unlikely to occur, but it consumes a large amount of power during operation and can be operated with dry batteries or small-capacity storage batteries. difficult.

"Type of flow meter (https://www.keyence.co.jp/ss/products/process/flowmeter/type/)" in "Flow knowledge.COM" on the KEYENCE CORPORATION website "Flow switch for water (https://www.smcworld.com/products/pickup/ja-jp/switch_sensor/f_liquid.html)" in "Product Information" on the SMC Corporation website Showa Kikai Keiso Co., Ltd. website "Product List (https://www.showa-kk.com/product.html)"

Flow meters and flow sensors that insert a structure larger than the cross-sectional area of the conventional water distribution path do not have a problem of clogging for dust-free water such as tap water, but water can be drawn from rivers and irrigation canals. Water mixed with garbage and mud may flow into the distribution route in the pumped agricultural water. As a result, there is a risk of malfunction due to clogging of both, and maintenance is troublesome.

Since this sensor has two metal detection electrodes with a diameter of 2-3 mm and a length of about 15-30 mm with respect to the cross-sectional area of the water distribution path, and a temperature sensor with a diameter and length of about 3-5 mm, it operates due to dust clogging. Defects are unlikely to occur. In addition, since there are no mechanically moving parts, maintenance is not required.

A case where this sensor is attached to the water distribution path of the resin pipe (15) will be described (FIG. 3). A resin pipe (15) with a metal detection electrode (16) (detection electrode anode (2a), detection electrode cathode (2b), both made of stainless steel) and a water temperature sensor (18) attached to an electrode fixing substrate (17). ), And the signal line from the electrode fixing substrate (17) is connected to the signal processing system (3)-(14) (FIG. 1).

The principle of this sensor is that when the detection electrode anode (2a) and the detection electrode cathode (2b) are in water, electricity flows to the cathode (2b) when electricity is passed from the anode (2a). When electricity is passed from the anode (2a) while the capacitor (4) is discharged, the capacitor (4) is charged via the cathode (2b). With the start of energization of the anode (2a) as t0, the time tCR until the voltage between the capacitor (4) and GND reaches the threshold value Vth is measured (FIG. 1). Vth is 63.22% of the voltage applied to the anode (2a). Capacitor (4) Charging time tCR is considered to be equivalent to the electrical resistance between the two electrodes of the anode (2a) and cathode (2b), and the longer the charging time, the greater the electrical resistance. The electrical resistance becomes infinite when water is not in the resin pipe (15), but decreases when it flows. Whether the water is stagnant or flowing is determined by obtaining the flow velocity from the difference in the change over time of tCR.

As the operation of the signal processing system (3)-(14), first, the measurement condition setting unit (10) sets the output voltage value of the digital analog converter (6) for outputting the threshold voltage Vth of the comparator (5). To do. The electrode control unit (8) resets the increment counter (9), energizes the anode (2a), and then starts adding the increment counter (9). The operating clock 1 MHz of the increment counter (9) is generated by the counter clock generator (3). The voltage between the capacitor (4) and GND connected to the cathode (2b) side and the threshold voltage Vth of the output of the digital analog converter (6) are compared by the comparator (5), and if it becomes Vth or more, it is added. Turn off the energization of the anode (2a).

The water temperature sensor (1,18) and the water temperature measuring unit (7) measure the water temperature in the vicinity of the detection electrodes (2a, 2b, 16). The temperature correction unit (11) corrects the tCR added by the increment counter (9) (Equation 1).
The flow velocity calculation unit (12) divides the absolute value of the difference between the previous sample and the current K25 by the sampling interval to obtain the flow velocity (Equation 2). In order to moderate the fluctuation on the flow side, a simple moving average of the flow velocity is calculated (Equation 3). The number of moving averages was set to 5. If the spMA is equal to or greater than the threshold value spth, the water flow determination unit (13) determines that water is flowing. If it is less than the threshold value, it is determined that the signal is not flowing, and the result output unit (14) outputs an alarm signal.

In irrigation such as paddy fields, water from rivers, irrigation canals and wells is pumped by a portable engine pump (20) or an electric pump or a pump installed in a pumping station and supplied to the field (23). In the case of the engine pump (20), the water supply is stopped when the fuel runs out, so a means for notifying the user of the stop is required. In the embodiment of FIG. 4, the resin pipe (15) of FIG. 3 with this sensor attached is installed on the discharge side. The resin pipe (15) used a VP for general use with a nominal diameter of 50 mm, the condenser (4) used 0.1 μF, and the water temperature sensor (1,18) used a thermistor. The detection electrodes (2a, 2b, 16) were inserted 20 mm into the tube. When a wireless modem is connected to the result output unit (14) and the water supply is stopped, an alarm is transmitted wirelessly to the user.

In the embodiment of FIG. 5, a cut view of the discharge portion (25) ((24) of a commercially available paddy field faucet (24) (the water discharge portion is shown in a cut diagram for easy understanding) as viewed from above. ), The detection electrode (2a, 2b, 16), the electrode fixing substrate (17), and the water temperature sensor (1,18) are attached to this sensor part set. This makes it possible to detect water supply interruptions.

In recent years, the number of white immature grains of paddy rice has been increasing due to the tendency of high summer temperature, and it is said that nighttime irrigation, which has a lower water temperature than daytime, is effective as a countermeasure. However, if water is supplied at night, it is necessary to patrol the fields and pumping stations at night. There are commercially available automatic water faucets that can automatically supply and stop water at the set time and can also be operated wirelessly from a remote location, but when the water faucet is closed, dust such as dead leaves and tree branches is buried and it closes completely. It may not be there. These automatic faucets are equipped with a sensor for preventing motor overload and a lower limit of the ball screw, and can detect the biting of dust in the faucet when it is closed. On the contrary, even if the automatic faucet is opened as set, the water supply status cannot be detected if the water supply is interrupted due to a problem with the pumping station or the water distribution route. Some of them can be connected to a water level gauge, but it takes time to raise the water level in a wide field, which causes a large time lag in detecting supply abnormalities. Since the water level gauge is installed in the field, it may be clogged with mud or dust and may not operate normally depending on the structure.

By attaching this sensor to the outlet of an automatic faucet (also commercially available) equipped with a motor and a control device on a faucet shaped as shown in Fig. 5, water can be supplied due to problems with the pumping station or water distribution route. Interruption can be detected. If this sensor is attached to an automatic water faucet that does not have a wireless communication function and a wireless modem is connected to the result output unit (14), the water supply status can be transmitted wirelessly to the user.

It is a signal processing block diagram of this invention. It is a time-dependent graph of the voltage between the detection electrodes (2a, 2b, 16) of this sensor. This is an example in which this sensor is attached to one of the resin pipes of the embodiment. FIG. 3 is an example in which the sensor shown in FIG. 3 of the embodiment is used in an engine pump. This is an example in which this sensor, which is one of the embodiments, is attached to the discharge port of the faucet.

1: Water temperature sensor 2a: Detection electrode anode 2b: Detection electrode cathode 3: Counter clock generator 4: Capacitor 5: Comparator 6: Digital analog converter 7: Water temperature measurement unit 8: Electrode control unit 9: Increment counter 10: Measurement condition setting Unit 11: Temperature correction unit 12: Flow velocity calculation unit 13: Water flow determination unit 14: Result output unit 15: Resin pipe 16: Detection electrode (2a, 2b)
17: Electrode fixing substrate 18: Water temperature sensor (1)
19: Intake side piping for rivers, irrigation canals and wells 20: Engine pump 21: Discharge side piping 22: This sensor attached to the discharge side 23: Field 24: Water faucet 25: This sensor installed inside the water faucet

Claims (1)

A means of inserting two rod-shaped metal detection electrodes (2a, 2b) and a water temperature sensor (1) for temperature correction into the water distribution path to obtain the flow velocity from the change over time in the electrical resistance of water, the flow velocity and its arbitrary A flow sensor having a means for determining the flow by comparing the set threshold values of.

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