JP3234984U - Antenna and manhole remote monitoring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna and a manhole remote monitoring device capable of transmitting radio waves in a manhole to the outside of the manhole without replacing a manhole cover. An antenna 4 that radiates data output from a data transmission device installed in a manhole as an electromagnetic wave, and a permanent magnet 4a that is closely fixed to the back side of a cast iron manhole lid 1b that closes the manhole. The permanent magnet has an antenna body 4c fixed to the permanent magnet via an insulator 4b, and the permanent magnet has a disk shape having a diameter of λ / 21 to λ / 19 with respect to the wavelength λ of the electromagnetic wave. [Selection diagram] FIG. 6

Description

The present invention relates to, for example, an antenna and a manhole remote monitoring device for transmitting information such as a water level and a flow rate in a manhole to the outside of the manhole by radio waves.

Conventionally, as a method of transmitting radio waves in a manhole to the outside of a manhole, there is a method in which the manhole cover itself is processed so that radio waves can pass through (see Patent Document 1).

JP-A-2002-54167.

However, in order to replace the conventional manhole cover with a manhole cover processed as described above, it is often necessary to replace the lid frame (reception frame) accompanied by road excavation.

The present invention has been made in consideration of the above-mentioned matters, and an object thereof is to provide an antenna and a manhole remote monitoring device capable of allowing radio waves in the manhole to be sent out of the manhole without replacing the manhole cover. To do.

In order to achieve the above object, the antenna according to the present invention is an antenna that radiates data output from a data transmission device installed in a manhole as an electromagnetic wave, and is located on the back side of a cast iron manhole lid that closes the manhole. It has a permanent magnet that is closely fixed and an antenna body that is fixed to the permanent magnet via an insulator, and the permanent magnet has a diameter of λ / 21 to λ / 19 with respect to the wavelength λ of the electromagnetic wave. It has a disk shape (claim 1).

On the other hand, in order to achieve the above object, the manhole remote monitoring device according to the present invention includes a sensor installed in the manhole, a data transmission device installed in the manhole and input with the measured value obtained by the sensor. It is equipped with an antenna that radiates data output from this data transmission device as an electromagnetic wave, and the antenna is a permanent magnet that is closely fixed to the back side of a cast iron manhole lid that closes the manhole, and an insulator to the permanent magnet. The permanent magnet has an antenna body fixed via the above, and the permanent magnet has a disk shape having a diameter of λ / 21 to λ / 19 with respect to the wavelength λ of the electromagnetic wave (claim 2).

In the manhole remote monitoring device, the cable connecting the data transmission device and the antenna may be shorter than the distance from the data transmission device to the bottom of the manhole (claim 3).

According to the present invention, an antenna and a manhole remote monitoring device capable of allowing radio waves in the manhole to be sent out of the manhole without replacing the manhole cover can be obtained.

That is, in the antenna devised according to each claim of the present application, a virtual antenna is generated on the upper part of the manhole cover by bringing the antenna into close contact with the back side of the manhole cover, and the antenna is external to the manhole even though it is inside the manhole. Communication is possible. Moreover, since it is only necessary to bring the antenna into close contact with the back side of the manhole cover and it is not necessary to replace the manhole cover, it is not necessary to replace the lid frame (reception frame) accompanied by road excavation, and it can be carried out extremely easily.

Further, in the antenna of the present invention, a magnetic field is concentrated by using a disk-shaped permanent magnet having a diameter of λ / 21 to λ / 19 (about λ / 20) with respect to the wavelength λ of the radiated electromagnetic wave, and a manhole is generated. It is possible to increase the amount of electromagnetic waves emitted from the lid.

In the manhole remote monitoring device according to claim 3, even if the antenna is unexpectedly removed from the manhole cover, the antenna is prevented from falling to the bottom of the manhole.

It is explanatory drawing which shows schematic structure of the manhole remote monitoring apparatus which concerns on one Embodiment of this invention. It is a photograph which shows the structure of the main part of the manhole remote monitoring apparatus. (A) to (C) are photographs of the antenna used in the manhole remote monitoring device. It is a table which shows the content and result of the experiment performed under various conditions. (A) and (B) are photographs showing an example of insulation treatment. It is explanatory drawing of the antenna used for the manhole remote monitoring apparatus.

Embodiments of the present invention will be described below with reference to the drawings.

The manhole remote monitoring device shown in FIG. 1 is derived from a sensor 2 installed in the manhole 1, a data transmission device 3 also installed in the manhole 1 and to which the measured value obtained by the sensor 2 is input, and the data transmission device 3. It includes an antenna 4 that emits output data (data corresponding to the measured value, etc.) as an electromagnetic wave.

Here, in addition to the data logger unit, the data transmission device 3 has a data transmission device 3 itself, a sensor 2 connected to the data transmission device 3, a power supply unit for driving the antenna 4, and the like. The data logger unit accumulates the data measured by the sensor 2, processes the data into necessary data by analyzing the data, and outputs this data at any time. Then, the output data is carried to, for example, a management computer having a communication function (for example, a personal computer having a modem that functions as a communication unit) or a cloud server located in a place desired by the user (for example, an office). It is sent via the telephone network. That is, these data can be contacted via the Internet through a mobile terminal such as a smartphone or tablet or a stationary terminal such as a PC, and remote monitoring of the manhole 1 is possible.

On the other hand, the manhole 1 has a sewage culvert 1a to be monitored and, for example, a cast iron manhole cover 1b that closes the opening thereof.

Then, in the present embodiment, as shown in FIG. 2, the antenna 4 is brought into close contact with the back side of the manhole cover 1b. Specifically, the antenna 4 has a shape as shown in FIGS. 3A to 3C, and a magnet (permanent magnet) 4a is contained in the pedestal, whereby the antenna 4 can be fixed to the back side of the manhole cover 1b. It has become.

More specifically, as shown in FIG. 6, the antenna 4 has a permanent magnet 4a for fixing to the back side of the manhole cover 1b, and an antenna body 4c fixed to the permanent magnet 4a via an insulator 4b. ..

In FIG. 6, reference numeral 6 is a cable (for example, a feeding line) connecting the data transmission device 3 and the antenna 4, and the distance (for example, the data transmission device 3) from the data transmission device 3 to the bottom of the manhole 1 is connected to this cable 6. By making the antenna 4 shorter than the installation height), even if the antenna 4 is unexpectedly removed from the manhole lid 1b, the antenna 4 is prevented from falling to the bottom of the manhole 1. In this example, the cable 6 is shorter than the cable (for example, data line) 7 (see FIG. 1) connecting the data transmission device 3 and the sensor 2.

The permanent magnet 4a has a disk shape having a diameter of λ / 21 to λ / 19 (about λ / 20) with respect to the wavelength λ of the electromagnetic wave. As a result, magnetic field concentration can be caused and the amount of electromagnetic waves radiated from the manhole cover 1b can be increased. In fact, the inventors have experimentally confirmed that when a copper plate is used instead of the permanent magnet 4a and the antenna is erected under the manhole cover 1b, the amount of electromagnetic waves emitted from the manhole cover 1b is reduced. (When the circumference of the manhole cover 1b is insulated).

Here, with respect to the manhole 1, radio waves from the outside are electromagnetically shielded by the iron manhole cover 1b. Therefore, it is extremely difficult to communicate between the equipment inside the manhole 1 and the radio base station outside by the usual method. However, in the present embodiment, by directly bringing a part of the antenna 4 into close contact with the back side of the manhole cover 1b, an electromagnetic magnetic field is applied to the manhole cover 1b from the back side of the manhole cover 1b, and an electromagnetic magnetic field is applied to the inside and the surface of the manhole cover 1b. And realize a virtual antenna on the upper part of the manhole cover 1b. That is, by bringing the feeding end of the antenna 4 close to the back side of the manhole cover 1b, a virtual antenna is generated, and communication with the outside is possible even though the antenna 4 is inside the manhole 1.

Further, by interposing an insulator 5 between the manhole cover 1b and the support portion (reception frame or hinge portion) of the manhole cover 1b to realize electrical separation between the manhole cover 1b and the ground (earth), it is virtual. The performance of the antenna will be improved. Here, as a method of interposing the insulating material 5, the insulating paint is sprayed or applied to the contact portion of the manhole cover 1b with the support portion or the contact portion of the support portion with the manhole cover 1b, or an insulating tape is applied. It is conceivable to paste it. Note that FIGS. 5A and 5B show a state in which an insulating tape (vinyl tape) is attached to the support portion to perform an insulating treatment.

FIG. 4 shows the contents and results of Experiments 1 to 6 in which the radio field intensity of the antenna 4 was measured outside the manhole 1 under various conditions. In Experiments 1, 3 and 4, the antenna 4 was closely fixed downward to the back side of the manhole cover 1b in the manhole 1, and the circumference of the manhole cover 1b was insulated. In Experiment 2, the antenna 4 was arranged downward from the manhole cover 1b, and the antenna 4 was directed downward. In Experiment 5, the antenna 4 was placed above the manhole cover 1b, and in Experiment 6, the antenna 4 was placed on the above-ground asphalt near the manhole cover 1b. Further, in Experiment 4, a car was placed on the manhole cover 1b, and in Experiment 5, water having a depth of 10 mm was poured on the manhole cover 1b by surrounding the manhole cover 1b with a weir (assuming rainy weather).

The radio wave intensities of the antennas 4 of Experiments 1 to 6 were -96db, non-communication (radio waves do not fly to the outside), -101db, -91db, -63db, and -76db.

As can be understood from the contents of each experiment, Experiments 1, 3 and 4 are examples of the present invention, Experiment 2 is a conventional example (when the antenna 4 is installed in the manhole 1), and Experiments 5 and 6 are reference examples. (When the antenna 4 is installed outside the manhole 1).

Then, as is clear from comparing Experiment 1 with Experiment 2, when the antenna 4 is closely fixed to the back side of the manhole cover 1b and is insulated, the radio wave strength of the antenna 4 is increased. ..

In Experiments 1 and 4, the radio field strength of the antenna 4 increases when water accumulates on the upper side of the manhole cover 1b, although the electrical resistance of the cast iron plate constituting the manhole cover 1b is large, but it is filled with water. This is because a layer that conducts electricity is added to the surface, and the electromagnetic field is strengthened. Unless it is distilled water, water conducts electricity and absorbs radio waves at the same time, but if the water layer is thin compared to the wavelength, the propagation loss is negligible. While the wavelength of the radio wave used is about 30 cm, the layer of water is 1-2 cm, so the radio wave loss is in a negligible range.
Therefore, from the results of this experiment, it can be seen that the manhole cover itself plays the role of an antenna.

Further, as shown in Experiment 3, even when the car is placed on the manhole cover 1b, the radio waves in the manhole 1 can be sent out of the manhole 1.

As described above, in the manhole remote monitoring device of the present embodiment, it is possible to send the radio waves in the manhole 1 to the outside of the manhole 1 without replacing the manhole cover 1b.

It should be noted that the present invention is not limited to the above-described embodiment, and it is needless to say that the present invention can be variously modified and implemented without departing from the gist of the present invention.

For example, the sensor 2 is not limited to measuring the flow rate, but may measure water quality, gas concentration, pressure, temperature, etc., or may measure data related to a plurality of items as described above. good.

1 Manhole 1a Sewage culvert 1b Manhole cover 2 Sensor 3 Data transmission device 4 Antenna 4a Permanent magnet 4b Insulator 4c Antenna body 5 Insulator 6 Cable 7 Cable

Claims (3)

An antenna that radiates data output from a data transmission device installed in a manhole as electromagnetic waves.
It has a permanent magnet for fixing to the back side of a cast iron manhole cover that closes the manhole, and an antenna body fixed to the permanent magnet via an insulator.
The permanent magnet is a disk-shaped antenna having a diameter of λ / 21 to λ / 19 with respect to the wavelength λ of the electromagnetic wave. It is equipped with a sensor installed in the manhole, a data transmission device installed in the manhole to input the measured value obtained by the sensor, and an antenna that emits data output from the data transmission device as an electromagnetic wave.
The antenna has a permanent magnet for fixing to the back side of a cast iron manhole cover that closes the manhole, and an antenna body fixed to the permanent magnet via an insulator.
The permanent magnet is a manhole remote monitoring device having a diameter of λ / 21 to λ / 19 with respect to the wavelength λ of the electromagnetic wave and having a disk shape. The manhole remote monitoring device according to claim 2, wherein the cable connecting the data transmission device and the antenna is shorter than the distance from the data transmission device to the bottom of the manhole.

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