JP2014199227A - Receiver of underground-pipe detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the receiver of an underground-pipe detection device, capable of avoiding influence of an interfering magnetic field as much as possible and sufficiently improving detection accuracy.SOLUTION: The receiver 1 of an underground-pipe detection device includes a receiver coil 1 connected so that the outputs of two coils 2A and 2B arranged in a horizontal direction at a predetermined distance 2l and having axis lines Ao and Bo inclined at a predetermined angle θ inside from a perpendicular direction V are oppositely polar. The two coils 2A and 2B have preferably a distance 2l of 20-40 cm and an inclination angle θ of 5-20°.

Description

  The present invention relates to a receiver of a buried pipe detection device that detects the position and depth of a buried pipe having conductivity, such as a gas pipe and a water pipe buried in the ground, from the ground.

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 method of detecting the buried pipe, an alternating current generated by the transmitter is caused to flow through the buried pipe so that a magnetic field is generated 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 induced. A primary magnetic field is formed around the induction coil, guided to the coil, an alternating current is passed through the buried pipe by the primary magnetic field to generate a secondary magnetic field around the buried pipe, and the secondary magnetic field is captured by the receiver. There is a guidance method or the like (see FIG. 11).

In any case, the magnetic field generated around the buried pipe is captured by a receiver placed on the ground, but this receiver also captures the primary magnetic field from the transmitter and the disturbing magnetic field in the surrounding environment. Therefore, it is difficult to perform accurate detection.
Therefore, a buried pipe detection device has been proposed in which a plurality of coils are arranged in parallel and connected to each other in reverse polarity, and the magnetic field generated around the buried pipe is captured as a detector constituting the receiver. (See Patent Document 1).

  According to this buried pipe detection device, the influence of the primary magnetic field and the disturbing magnetic field is canceled by connecting a plurality of coils in reverse polarity, so that the magnetic field generated around the buried pipe is output as much as possible. It was possible to improve the detection accuracy.

Japanese Patent Publication No.49-9388

  According to the buried pipe detection device disclosed in Patent Document 1, the detection accuracy could be improved, but this method also has sensitivity in the lateral direction of the coil, for example, connection in the case of implementing the loop method The detection accuracy is not sufficient because a disturbance magnetic field generated from a long metal object such as a cable or a guard rail is detected in the lateral direction.

  The present invention has been made to solve such a conventional problem, and the object thereof is, for example, in the lateral direction such as a connection cable or a guard rail when the loop method is performed. An object of the present invention is to provide a receiver of a buried pipe detection device that can sufficiently improve the detection accuracy by avoiding the influence of a disturbing magnetic field generated from a long metal object as much as possible.

  In order to achieve the above object, the receiver of the buried pipe detection device of the present invention arranges two coils at a predetermined distance in the horizontal direction, and inclines the axis of each coil inward from the vertical direction by a predetermined angle, A reception coil is configured in which the outputs of the coils are connected to have opposite polarities.

  Here, the distance 2l between the two coils is preferably 20 to 40 cm, and the inclination angle θ of each coil is preferably 5 to 20 °.

  According to the receiver of the buried pipe detection device of the present invention, for example, the influence of a disturbing magnetic field generated from a long metal object existing in a lateral direction, such as a connection cable or a guard rail when the loop method is performed, is avoided as much as possible. Thus, the detection accuracy can be sufficiently improved.

It is a block diagram of the receiving coil of the buried pipe detection device of the present invention. It is explanatory drawing which shows the positional relationship of the receiving coil and buried pipe shown in FIG. It is a block diagram of the receiver of the buried pipe detection device of the present invention. It is a graph which shows the directivity of a receiving coil. It is a graph which shows the relationship between the inclination-angle of a coil, and a half value angle. It is a graph which shows the relationship between the inclination-angle of a coil, and a half value angle. It is a graph which shows the relationship between the inclination-angle of a coil, and a half value angle. 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 receiver of a buried pipe detection device of the invention will be described with reference to the drawings.
FIG. 1 is a configuration diagram of a receiving coil of the buried pipe detection device of the present invention, FIG. 2 is an explanatory diagram showing a positional relationship between the receiving coil and the buried pipe shown in FIG. 1, and FIG. 3 is a buried pipe detecting of the present invention. It is a block diagram of the receiver of an apparatus.

  As shown in FIG. 3, the receiver 1 of the buried pipe detection device of the present invention includes a receiving coil 2, a voltage amplifier 3, a noise filter 4, a voltage amplifier 5, a detector 6, and a display 7.

As shown in FIG. 1, the receiving 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 at a predetermined angle inward from the vertical direction V. It is inclined by θ.
And the output of each coil 2A, 2B is connected so that it may become a reverse polarity, and the output is transmitted to the voltage amplifier 3. FIG.

Since the receiving coil 2 is positioned immediately above the buried pipe P to detect the position and depth of the buried pipe P, the positional relationship between the receiving coil 2 and the buried pipe P is as shown in FIG.
Here, y represents the distance from the center of the two coils 2A and 2B to the buried pipe P, and φ represents the angle obtained by rotating the two coils 2A and 2B around the horizontal axis.

  Here, the output of the receiving coil 2, that is, the induced electromotive force E of the two coils 2A and 2B can be expressed by the following equation.

First, when 2l = 20 cm, θ = 10 °, and y = 1 m, and the two coils 2A and 2B are rotated 360 ° around the horizontal axis (when φ is changed by 0 to 360 °) The directivity of the receiving coil 2 was confirmed.
The directivity of the receiving coil 12 composed of a differential coil (when 2l = 20 cm and θ = 0 °) and the receiving coil 22 composed of a single coil (when θ = 0 °) is the same as described above. It was confirmed.

The confirmation result of directivity is shown in FIG. This graph is normalized with the maximum value of the output of each of the receiving coils 2, 12, 22 as 1.
As can be seen from FIG. 3, the receiving coil 2 has high sensitivity in the downward direction but low sensitivity in the upward direction and the lateral direction. As a result, the receiving coil 2 has high directivity in the downward direction compared to the receiving coil 22 and high resolution, so that accurate position detection can be performed and lateral sensitivity is low compared to the receiving coil 22. It can be understood that it is difficult to be affected by guardrails.

Next, (1/2 power, 1/2 1/2 is the ^voltage) 1/2 as compared with the sensitivity downward is defined as half-value angle the angle φ to be the sensitivity of, and a measure for evaluating the directionality .
And it changed into 2l = 10-100cm, (theta) = 0-90 degrees, y = 0.5,1.0,2.0m, and the change of the half value angle was confirmed.

The confirmation results of the half-value angle are shown in FIGS. The half-value angle of the receiving coil 22 composed of a single coil is 90 °.
Here, since it is meaningless to have a half-value angle larger than 90 °, the distance between coils 2l = 20-40 cm and the coil inclination angle θ = 5-20 ° for a buried pipe having a depth of 0.5-2.0 m. Is understood to be appropriate.

The receiver of the buried pipe detection device of the present invention is configured such that the axes of the two coils are inclined inward from the vertical direction by a predetermined angle, and the outputs of the coils are connected to have opposite polarities. Because the sensitivity is increased and the lateral sensitivity is decreased, for example, the influence of disturbing magnetic fields generated from long metal objects such as connection cables and guard rails in the lateral direction when the loop method is implemented is avoided as much as possible. Thus, the detection accuracy can be sufficiently improved.

1 Receiving coil 2A, 2B Coil P Buried pipe

Claims (3)

A receiving coil is constructed in which two coils are arranged at a predetermined distance in the horizontal direction, the axis of each coil is inclined at a predetermined angle inward from the vertical direction, and the output of each coil is connected to have a reverse polarity. A receiver for a buried pipe detection device. The receiver of the buried pipe detection device according to claim 1, wherein an inclination angle θ of each coil of the reception coil is 5 to 20 °. The receiver of the buried pipe detection device according to claim 1 or 2, wherein a distance 21 between the two coils of the reception coil is 20 to 40 cm.

Images