JP6234690B2 - Transmitter of buried pipe detection device and induction coil for transmitter - Google Patents

Description

The present invention relates to a transmitter of a buried pipe detection device for detecting the position and depth of a buried pipe having conductivity, such as a gas pipe and a water pipe buried in the ground, and an induction coil for the transmitter .

2. Description of the Related Art Conventionally, a buried pipe detection device using electromagnetic induction has been known as a device for detecting the position and depth of a conductive buried pipe such as a gas pipe or a water pipe buried in the ground from the ground.
As a buried pipe detection method, an alternating current generated by a transmitter is passed through the buried pipe to generate a magnetic field around the buried pipe, and this magnetic field is captured by the receiver (see FIG. 8).
The AC current generated by the transmitter can be passed through the buried pipe as a direct method (see FIG. 9) or a loop method (see FIG. 10) in which the transmitter is directly connected to the buried pipe, or the transmitter output is used as an induction coil. An induction method in which a primary magnetic field is formed around a guiding induction coil, an alternating current is caused to flow through the buried pipe by the primary magnetic field, a secondary magnetic field is generated around the buried pipe, and the secondary magnetic field is captured by a receiver. (See FIG. 11), but the guidance method is widely used because of its simplicity.

In any case, the magnetic field generated around the buried pipe is captured by a receiver placed on the ground. However, when the induction method is adopted, transmission is performed so that the transmitter is not affected by the primary magnetic field. It was necessary to arrange the receiver and the receiver at a considerable distance.
In addition, when there is another buried pipe congested in the buried pipe for the purpose of exploration, an alternating current also flows in this buried buried pipe, and the disturbing magnetic field generated from this deteriorates the detection accuracy. End up.
Therefore, as an induction coil that constitutes a transmitter, a pair of coils are arranged vertically in parallel, these coils are connected in reverse polarity, a magnetic field is formed around them, and an alternating current is applied to a buried pipe located in this magnetic field. A buried pipe detection device has been proposed (see Patent Document 1).

According to this buried pipe detection device, the vertical magnetic flux density of the primary magnetic field is increased and the horizontal magnetic flux density is decreased by arranging a pair of coils vertically in parallel. Can now be closer to the vessel.
In addition, the directivity in the downward direction becomes sharp and the alternating current flowing in the buried pipe congested with the buried pipe targeted for exploration is reduced, so that the exploration accuracy can be improved.

JP-A-6-59048

However, according to the buried pipe detection device disclosed in Patent Document 1, in an induction coil in which a pair of coils are vertically arranged in parallel and are connected in reverse polarity, the magnetic fields generated by the coils cancel each other out. For this reason, the primary magnetic field is weakened, and the current flowing through the buried pipe intended for exploration is also reduced.
In such a state, a secondary magnetic field having a sufficient strength for detection by the receiver cannot be generated, and the detection accuracy of the receiver is lowered due to the influence of external noise and the like. In order to generate a secondary magnetic field having a sufficient strength for detection by the receiver, there is no doubt that the output of the transmitter is increased, and problems such as an increase in the size of the transmitter occur.

  The present invention has been made in order to solve such conventional problems, and the object of the present invention is to provide these buried pipes even if other buried pipes are present near the buried pipe. To provide a transmitter of a buried pipe detection device that does not cause a current to flow as much as possible, does not reduce the strength of a secondary magnetic field generated in a buried pipe to be searched, and does not reduce the detection accuracy of a receiver. It is in.

In order to achieve the above object, the transmitter of the buried pipe detection device of the present invention arranges two coils at a predetermined distance in the horizontal direction, and the axis of each coil intersects above the coils. The transmitter coil is configured such that the axis of each coil is tilted inward from the vertical direction so that the tilt angle θ is 5 to 20 °, and the output of each coil is connected to have a reverse polarity. To do.

Here, the distance 2l between the two coils of the transmitter induction coil is preferably 40 to 60 cm .

  According to the transmitter of the buried pipe detection device of the present invention, even when there is another buried pipe that is congested in the vicinity of the buried pipe targeted for the exploration, current is not passed through these buried pipes as much as possible. Since the strength of the secondary magnetic field generated in the target buried pipe is not reduced, the detection accuracy of the receiver is not lowered.

It is a block diagram of the induction coil of the buried pipe detection device of the present invention. It is explanatory drawing which shows the positional relationship of the induction coil and buried pipe shown in FIG. It is a block diagram of the transmitter of the buried pipe detection device of the present invention. It is a graph which shows the relationship between the inclination-angle of a coil, and a half value width. It is a graph which shows the relationship between the inclination-angle of a coil, and a half value width. It is a graph which shows the relationship between the inclination-angle of a coil, and a half value width. It is a graph which shows the induction efficiency of an induction coil. It is explanatory drawing which shows the principle of a buried pipe detection apparatus. It is explanatory drawing which shows a direct method as a method of flowing an alternating current through a buried pipe. It is explanatory drawing which shows a loop method as a method of flowing an alternating current through a buried pipe. It is explanatory drawing which shows the induction | guidance | derivation method as a method of flowing an alternating current through a buried pipe.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a preferred embodiment of a transmitter of a buried pipe detection device of the invention will be described with reference to the drawings.
FIG. 1 is a configuration diagram of an induction coil of the buried pipe detection device of the present invention, FIG. 2 is an explanatory diagram showing a positional relationship between the induction coil and the buried pipe shown in FIG. 1, and FIG. 3 is a buried pipe detection of the present invention. It is a block diagram of the transmitter of an apparatus.

  As shown in FIG. 3, the transmitter 1 of the buried pipe detection device of the present invention includes an induction coil 2, a voltage amplifier 3, and a transmitter 4.

As shown in FIG. 3, the induction coil 2 has two coils 2A and 2B arranged at a predetermined distance 2l in the horizontal direction, and the axes Ao and Bo of the coils 2A and 2B are set inward from the vertical direction V by a predetermined angle. It is inclined by θ.
And the output of each coil 2A, 2B is connected so that it may become reverse polarity, and an alternating current is sent from the voltage amplifier 3. FIG.

Since the induction coil 2 is positioned above the buried pipe P and generates a magnetic field in the region where the buried pipe P is located, the positional relationship between the induction coil 2 and the buried pipe P is as shown in FIG. .
Here, x represents the horizontal distance from the center of the two coils 2A and 2B to the buried pipe P, and y represents the vertical distance from the center of the two coils 2A and 2B to the buried pipe P.

  Here, the induced electromotive force e generated in the buried pipe P when an alternating current is passed through the induction coil 2, that is, the two coils 2A and 2B, can be expressed by the following equation.

First, compared to the case where the induction coil 2 is positioned directly above the buried pipe (x = 0 m), the horizontal distance x ′ at which the induced electromotive force e becomes 1/2 ^1/2 ( ^{1/2 in} power) is reduced by half. The value range was defined as a scale for evaluating the induction characteristics.
Then, 2l = 10 to 100 cm, θ = 0 to 90 °, y = 0.5, 1.0, and 2.0 m were changed, and the change of the half-value width x ′ was confirmed.

The confirmation results of the half-value width x ′ are shown in FIGS. In the case of the induction coil 11 constituted by a single coil, it corresponds to y = 0.642, 1.286, 2.574, respectively.
Here, since the half-value width x ′ is 1.2 times or less than the depth y, there is no practical problem. Therefore, for an embedded pipe having a depth of 0.5 to 2.0 m, the inter-coil distance 2l = 40 to 60 cm, It is understood that a coil tilt angle θ = 5-20 ° is suitable.

Next, x = 0 m, y = 1 m were set and 2l = 10 to 100 cm and θ = 0 to 90 ° were changed to confirm the induction coil 2 induction efficiency.

The result of confirming the induction efficiency is shown in FIG. This graph is normalized by setting the value of the induced electromotive force of the induction coil 11 composed of a single coil to 1.
Here, since there is no practical problem if the induction efficiency is 0.3 to 0.5, the distance between the coils 2l = 40 to 60 cm and the coil inclination angle θ = 5 to 5 with respect to the buried pipe having a depth of 1.0 m. It will be appreciated that 20 ° is suitable.

The transmitter of the buried pipe detection device of the present invention inclines the axis of the two coils inward by a predetermined angle from the vertical direction, and connects the outputs of the coils so as to have opposite polarities. Since the magnetic flux density in the arrangement direction has been lowered, even if there are other buried pipes converging in the vicinity of the buried pipe intended for exploration, there is almost no current flowing through these buried pipes, and the buried pipe intended for exploration. Therefore, the intensity of the secondary magnetic field generated in the receiver is not reduced, and the detection accuracy of the receiver is not lowered.

1 Transmitter 2 Induction coil 2A, 2B Coil P Buried pipe

Claims (3)

Two coils are arranged at a predetermined distance in the horizontal direction, and the axis of each coil is inclined from the vertical direction to the inside so that the inclination angle θ is 5 to 20 ° so that the axis of each coil intersects above the coil. An induction coil for a transmitter of a buried pipe detection device , wherein the coil is connected so that the output of each coil has a reverse polarity. Transmitting dexterity induction coil buried pipe detection apparatus according to claim 1, wherein a distance 2l of the two coils of the transmission dexterity induction coil is 40～60Cm. A transmitter for a buried pipe detection device, comprising the transmitter induction coil according to claim 1 .

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