Variable-length induction antenna for controlling thrust direction in small-diameter tunneling method

Abstract

To provide an inductive antenna used for propulsion direction control in a propulsion method with a variable spacing between left and right coils to improve a measurement accuracy.SOLUTION: A width in a horizontal direction of left and right coils 5 provided on a horizontal fixing frame 1 supported by leg bodies 2 is configured to be variable. Arms 4 provided on tip ends of the coils 5 are rotatably provided along a frame front surface of the fixing frame at left and right of the fixing frame 1. Each of the arms 4 can be rotated from a position projecting from both ends of the fixing frame 1 to the upper inner side of the fixing frame 1 and is freely fixed.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a receiving antenna for controlling the direction of thrust in a small-diameter underground tunneling method, and more particularly to a variable-length induction antenna and a method of controlling the direction of thrust using said antenna. [Background technology]

[0002] As shown in Figures 9 and 10, the horizontal position measurement for directional control of the thrust head in the small diameter thrusting method utilizes the principle of electromagnetic induction, receiving electromagnetic waves from a transmitter in the thrust head with two coils on the left and right of an induction antenna installed at right angles on the ground thrust baseline (thrust planning line), estimating which side of the two coils the transmitter (thrust head) is on from the strength of the electromagnetic waves, and correcting the thrust direction of the thrust head according to this result. Therefore, the orientation of the induction antenna relative to the thrust baseline is extremely important, and there is a drawback in that measurements are not possible if the head's traveling direction deviates between the two coils.

[0003] The device disclosed in Patent Document 1 also controls the direction of thrust in a similar manner to that described above, but has been improved to improve measurement accuracy.

[0004] The device described in Patent Document 1 is a receiving device for controlling propulsion direction, which emits electromagnetic waves from a transmitting coil that is mounted at the tip of a propulsive body that can be propelled through the ground in a freely changeable direction and has an axis along the longitudinal direction of the body, and is mounted on the ground to freely receive the electromagnetic waves.A pair of receiving coils are arranged on the left and right of a fixing frame, with two receiving coils arranged on the left and right sides of a vertical plane that includes the propulsion plan line to the planned destination of the propulsive body in the middle, and the fixing frame is supported on a pan head having a tripod, and the depression angle that the axis of the left and right receiving coils make with the horizontal plane can be freely changed and the fixing frame can be fixed to any depression angle. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 9-273385 DISCLOSURE OF THEINVENTION [Problem to be solved by the invention]

[0006] However, conventional devices and methods, including that of Patent Document 1, have the following problems. Measurement accuracy is vague and difficult to understand, resulting in poor accuracy. Although position measurement using an induction antenna utilizes the principle of electromagnetic induction, it does not indicate the amount of deviation from the propulsion planned line in length, but rather displays it as numerical data of magnetic field strength, and only indicates on which side of the left or right coil the source (propulsion head) is located.

[0007] In addition, even if the difference in magnetic field strength between the left and right coils is reduced, it is not necessarily proportional to the amount of deviation, and as a result, in many cases, accuracy cannot be ensured. Technically, it is possible to indicate the amount of deviation from the planned baseline in terms of length, but since the electromagnetic induction method produces measurement results with errors due to various factors, for ease of use, such measurement results are displayed in terms of magnetic field strength.

[0008] In addition, this measurement system is designed so that if the transmitter in the thrust head is displaced from between the left and right coils, it becomes impossible to measure. Although this measurement method is easy to understand, it is impossible to predict how far it has displaced, which leads to a deterioration in the accuracy and instability of the reached position in short-distance construction.

[0009] In addition, it cannot be used for construction of a duct that rises up the wall of a house. Because the induction antenna has a total width of 1,172 mm, the minimum distance from the wall when constructing a duct that rises up the wall of a house is large at 586 mm, so the axial head must reach just before the part that rises up the wall on the side of the house, and then excavation must be carried out to bury the duct and connect it.

[0010] In order to solve the above-mentioned problems, the present invention aims to provide an induction antenna and a method of controlling thrust direction using the same, which can increase measurement accuracy by varying the distance between the left and right coils of an induction antenna used for thrust direction control in a thrusting method, and which can also be used in narrow spaces and for construction of pipelines close to the walls of houses, etc., by narrowing the distance between the left and right coils. [Means for solving the problem]

[0011] The invention of claim 1 is an induction antenna that is placed on a ground propulsion line and receives electromagnetic waves emitted from a propulsion head that propels underground, and has a horizontal width of left and right coils attached to a horizontal fixing frame supported by a leg body that is variable. The configuration in which the horizontal width of the left and right coils is variable is such that arms with coils at their tips are rotatably provided on the left and right sides of the fixing frame along the front surface of the fixing frame, and each arm is rotatable and fixable from a position protruding substantially horizontally from both ends of the fixing frame to the upper inside of the fixing frame. It is a variable-length induction antenna for controlling the thrust direction in small-diameter thrust construction methods.

[0012] The invention of claim 2 is as follows: The fixing frame is made of a member having an upwardly facing U-shaped cross section, and the base end of each of the arms is attached to an axis penetrating the front and rear plates of the fixing frame, and a plurality of pairs of through holes are provided in the front and rear plates of the fixing frame on an arc centered on each axis. When each arm is bent from the fixing frame, each arm is supported at that position by a rod inserted into one of the plurality of pairs of through holes. This variable-length induction antenna for thrust direction control in the small-diameter jacking method described in claim 1 is configured as follows. .

[0013] The invention of claim 3 is as follows: In an induction antenna that is placed on a ground propulsion plan line and receives electromagnetic waves emitted from a propulsion head that propels underground, the horizontal width of the left and right coils provided on a horizontal fixing frame supported on a leg body is variable, The configuration in which the horizontal width of the left and right coils is variable is such that the fixing frame is an upwardly facing U-shaped member, the left and right coils are supported by arms, the lower part of each arm is fitted into the fixing frame so as to be freely slidable along the longitudinal direction of the fixing frame, the coils protrude beyond the upper edge of the fixing frame, and the coils can protrude outward from both ends of the fixing frame. It is a variable-length induction antenna for controlling the thrust direction in small-diameter thrust construction methods. Effect of the Invention

[0017] According to the invention of claim 1 By changing the horizontal width of the left and right coils, it is possible to find the position where the received electromagnetic waves are strongest, and the position of the propulsion head, which is the source of the waves, can be more accurately estimated, improving the accuracy of propulsion direction control. Also, if the horizontal width of the left and right coils is set to a width slightly shorter than the maximum length to search for the position of the propulsion head, if the propulsion head is out of position in that state, the width of the left and right coils can be expanded to capture the position of the propulsion head. On the other hand, if the horizontal width of the left and right coils is kept narrow, it can be used in construction in narrow spaces between houses, which was not possible with the conventional method.

[0018] Furthermore, when erecting a pipeline close to the side wall of a house or the like, the left and right coils can be erected vertically or tilted inward to narrow the gap between these coils, and one of the coils can be brought closer to the wall, allowing the propulsion head to be erected with the end point being right next to the wall of the house or the like.

[0019] Also, The invention of claims 1 and 2 According to the above, the horizontal width of the left and right coils can be changed by a simple structure in which arms with coils at their tips are rotatably attached to the left and right ends of the fixing frame. In particular, claim 2 allows the arms to be easily fixed at a bent position relative to the fixing frame.

[0020] Also, The invention of claim 3 According to this, the supports for the left and right coils are fitted into the fixing frame, and each of these supports can slide, rotate and be fixed freely along the fixing frame, making it possible to vary the horizontal width of the left and right coils with a simple structure. [Brief description of the drawings]

[0022] [Figure 1] 1 is a front view of a variable length induction antenna according to a first embodiment of the present invention. [Diagram 2] 1 is a top front view of a variable length induction antenna according to a first embodiment of the present invention, with left and right arms standing vertically. FIG. [Diagram 3] 1 is a partial vertical cross-sectional side view of an upper portion of a variable length induction antenna according to a first embodiment of the present invention, in which left and right arms are set vertically. FIG. [Figure 4] 1 is a top front view of a variable length induction antenna according to a first embodiment of the present invention with left and right arms tilted diagonally inward. FIG. [Diagram 5] 1 is a top front view of a variable length induction antenna according to a first embodiment of the present invention with left and right arms tilted diagonally outward. FIG. [Figure 6] FIG. 1 is a side view showing a method for controlling a propulsion direction using a variable-length induction antenna according to a first embodiment of the present invention. [Figure 7] FIG. 1 is a front view of a variable length induction antenna according to a second embodiment of the present invention. [Figure 8] 1 is a side view of a vertical cross-sectional view of an upper portion of a variable-length induction antenna according to a second embodiment of the present invention. [Figure 9] FIG. 1 is a vertical cross-sectional image diagram showing a method of controlling the thrust direction in a conventional small-diameter jacking method. [Figure 10] FIG. 1 is an image diagram of position measurement of a thrust head in a thrust direction control method in a conventional small-diameter thrusting method. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] (Embodiment Example 1) A variable length inductive antenna A according to a first embodiment of the present invention will be described with reference to Figs.

[0024] This variable-length induction antenna A has a horizontal fixing frame 1 supported on legs 2 consisting of a tripod 2a. This fixing frame 1 is composed of a member with a U-shaped cross section with the opening facing upwards. One end of an arm 4 is attached to each of shafts 3 that penetrate the front and rear plates at the left and right ends of this fixing frame 1, and each arm 4 is freely rotatable around shaft 3.

[0025] A coil 5 for receiving electromagnetic waves is provided at the tip of each of these arms 4. A plurality of through holes 6 are provided in the front and rear plates of the fixing frame 1 centered on each of the shafts 3, and one through hole (not shown) is also provided at a corresponding position of each of the arms 4. Thus, each of the arms 4 is fixed by aligning one of the plurality of through holes 6 with the through hole of the arm 4, passing a bolt through the through hole 6, and tightening the bolt end with a nut. Note that an appropriate rod may be fitted instead of the bolt passing through the through hole. Furthermore, although a through hole is provided in each of the arms 4 as described above, a configuration may also be used in which a through hole is not provided in each of the arms 4, and a rod is passed through a pair of through holes 6 in the front and rear plates of the fixing frame 1, and one side of the arm 4 is abutted against the rod to support it.

[0026] Therefore, the left and right arms 4 can be extended horizontally outward from the fixing frame 1 (as shown in FIG. 1) and fixed in this state. Also, as shown in FIG. 2, each arm 4 can be bent at a right angle to the fixing frame 1 and fixed. Also, as shown in FIG. 4, if the left and right arms 4 are fixed at an angle inward from the fixing frame 1, the length between the left and right coils 5 will be the shortest.

[0027] Furthermore, as shown in FIG. 5, the left and right arms 4 can be fixed at various positions, such as tilting diagonally upward outward from the left and right ends of the fixing frame 1, thereby changing the spacing between the antennas 5 at the tips of the arms 4.

[0028] Next, FIG. 6 shows a method of thrust direction control using this variable-length induction antenna A.

[0029] A propulsion head 10 with an electromagnetic wave transmitter at its tip and the following propulsion pipe are propelled into the ground by a propulsion device 9 installed in the starting shaft 8. Meanwhile, a variable-length induction antenna A is installed at the midpoint on the ground on the propulsion baseline from the starting shaft 8 to the arrival shaft 11. At that time, the left and right arms 4 are bent at right angles to the fixing frame 1 and fixed.

[0030] As a result, if the thrust head 10 is shifted to the outside of the left and right coils 5, the left and right arms 4 can be spread outward to capture the thrust head 10. As a result, the direction of the thrust head 10 can be corrected. In this way, the positional shift of the thrust head 10 is reduced.

[0031] In addition, when propelling from the intermediate point to the destination point, i.e., the destination shaft 11, the left and right arms 4 are inclined toward the inside of the fixing frame 1 as shown in Fig. 6, or the left and right arms 4 are bent at right angles to the variable-length induction antenna A'. This allows the propelling head 10 to reach the destination shaft 11 within a narrow range from the propelling baseline.

[0032] By using the variable-length induction antenna A in this manner, the position of the propulsion head 10 can be detected more accurately by changing or narrowing the spacing between the left and right coils 5 and detecting the difference in strength of the received electromagnetic waves.

[0033] (Embodiment Example 2) Next, a variable length induction antenna B according to a second embodiment of the present invention will be described with reference to FIGS.

[0034] In this variable-length induction antenna B, a horizontal fixing frame 13 is supported on legs 14 consisting of a tripod 14a. This fixing frame 13 is composed of a member with a U-shaped cross section with an opening facing upward. The lower end of a plate-shaped arm 15 is slidably fitted into a groove 13a of this fixing frame 13, and an electromagnetic wave receiving coil 16 is fixed to the upper end of the arm 15. This coil 16 is located above the upper end of the fixing frame 13.

[0035] Two of these arms 15 and coils 16 are provided on the left and right sides of the fixing frame. Further, a long hole 17 is provided in the front plate and back plate of the fixing frame 13 in the longitudinal direction of the fixing frame 13. Further, a hole 18 is provided in one end of each of the arms 15 at a position corresponding to each of the long holes 17, and a bolt 19 is passed through the long hole 17 and the hole 18, and a wing nut 20 is screwed onto the end of the bolt 19.

[0036] As a result, when each wing nut 20 is loosened, each arm 15 becomes slidable within the groove 13a of the fixing frame 13, and when the wing nut 20 is tightened, the support body 15 is fixed. Also, a scale 21 is provided along the edge of the long hole 17 in the front plate of the fixing frame 1, and this scale 21 is graduated symmetrically on the left and right sides with the center point of the fixing frame 13 as the center.

[0037] 7, the left and right coils 16 can be fixed by laying the arms 15 sideways at both ends of the fixing frame 1 so that the left and right coils 16 protrude to the sides of the fixing frame 1. This allows the left and right coils 16 to have a spacing greater than the left and right width of the fixing frame 13.

[0038] With this configuration, the width of the gap between the left and right coils 16 can be easily changed, thereby making it possible to grasp the position where the received electromagnetic wave is strong and to accurately detect the position of the propulsion head 10.

[0039] In the variable-length induction antenna B of the second embodiment, the support 15 is fixed by passing a bolt 19 through the long hole 17 and the hole 18 of the support 15 and tightening it with a wing nut 20. However, if each support 15 is structured to fit snugly into the groove 13a, these long holes 17 etc. are not necessary, and each support 15 may be freely slidable and fixed within the groove.

[0040] The fixing frame 13 may be a single plate instead of a U-shaped member. In that case, a bolt 19 may be passed through one long hole 17 of the fixing frame 13 and through a hole 18 of each arm 15, and the end of the bolt 19 may be tightened with a wing nut 20.

[0041] The variable length induction antenna of the present invention is not limited to the configurations of the above-mentioned first and second embodiments, but may include other configurations as long as the horizontal gap between the left and right coils can be changed.

[0042] Further, the method of controlling the propulsion direction using the variable-length induction antennas A and B is not limited to that shown in FIG. 6, and any other suitable method can be applied. [Explanation of symbols]

[0043] A Variable-length Inductive Antenna A´ Variable length induction antenna Same as A B Variable length induction antenna 1 Fixing frame 2 Legs 2a tripod 3 axis 4 Arms 5 Coils 6 Through holes 8 Starting shaft 9 Propulsion device 10 Thrust head 11 Arrival shaft 13 Fixing frame 13a Groove 14 Legs 14a Tripod 15 Arm 16 Coil 17 long hole 18 hole 19 bolts 20 wing nut 21 scale

Claims

1. An induction antenna is placed on the ground on a propulsion line and receives electromagnetic waves emitted from a propulsion head propelling the ground. The horizontal width of the left and right coils mounted on a horizontal fixing frame supported by the legs is variable. The configuration in which the horizontal widths of the left and right coils are variable is characterized in that arms with coils at their tips are rotatably provided along the front surface of the fixing frame on the left and right sides of the fixing frame, and each arm is rotatable and fixable from positions protruding approximately horizontally from both ends of the fixing frame to the upper inside of the fixing frame. This variable-length induction antenna for thrust direction control in a small-diameter thrusting method is characterized in that

2. A variable-length induction antenna for controlling thrust direction in a small-diameter thrust construction method as described in claim 1, characterized in that the fixing frame consists of a member with an upward U-shaped cross-section, the base ends of each of the arms are respectively attached to an axis that passes through the front and rear plates of the fixing frame, and multiple pairs of through holes are provided in the front and rear plates of the fixing frame on an arc centered on each axis, and when each arm is bent from the fixing frame, each arm is supported in that position by a rod body inserted into a pair of these multiple pairs of through holes.

3. An induction antenna that is placed on a ground propulsion line and receives electromagnetic waves emitted from a propulsion head that propels the ground, The horizontal width of the left and right coils mounted on a horizontal fixing frame supported by the legs is variable. A variable-length induction antenna for thrust direction control in a small-diameter tunneling method, characterized in that the configuration in which the horizontal widths of the left and right coils are variable is configured such that the fixing frame is an upwardly facing U-shaped member, the left and right coils are supported by arms, the lower part of each arm is fitted into the fixing frame so as to be slidable along the longitudinal direction of the fixing frame, the coils protrude beyond the upper edge of the fixing frame, and the coils can protrude outward from both ends of the fixing frame.

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