JP2021136800A - Drill pipe multi-stage connector - Google Patents

Abstract

To provide a drill pipe multi-stage connection body, which can increase a transmission efficiency of power and expands a frequency band which can transmit the power.SOLUTION: In a drill pipe multi-stage connection body in which a drill pipe provided with a power reception coil 4 and a power transmission coil 5 connected by a rail track 6 each other to end parts 3a and 3b of a drill pipe body 3 forming the drill pipe is multi-stage connected, the power reception coil 4 and the power transmission coil 5 are spiral coils, and are arranged in annular grooves 3aa and 3ba formed in the end parts 3a and 3b of the drill pipe main body 3. High conductivity metal bodies 4A and 5A having an electric conductivity higher than that of the drill pipe main body 3 are arranged between a bottom surface and both side surfaces of the grooves 3aa and 3ba and the power reception coil 4 or the power transmission coil 5. Magnetic bodies 4B and 5B are arranged between the high conductivity metal bodies 4A and 5A and the power reception coil 4 or the power transmission coil 5, and are arranged on an open side of the grooves 3aa and 3ba of the power reception coil 4 or the power transmission coil 5.SELECTED DRAWING: Figure 2

Description

The present invention relates to a drill pipe multi-stage connector capable of transmitting electric power.

When performing submarine scientific drilling, a long multi-stage drill pipe connection body in which a number of drill pipes of about 10 m are connected is used. The replenishment work is carried out on a research vessel floating on the sea. If various sensors for detecting the excavation point or the stratum, a camera for photographing, etc. are attached to the tip or the like in association with this excavation work, a great result can be obtained by one excavation work. However, it is very difficult to secure the operating power of various measuring instruments and the like attached to the drill pipe multi-stage connector.

The main reason for the difficulty in securing the operating power of such a device is that the distance from the power source to the device is long. At the seams of the drill pipes, the wires and cables cannot be connected in the usual way due to structural problems. Therefore, a special method is required. For example, in Patent Document 1, an electric contact is formed at both ends of a drill pipe and they are connected by a line in the drill pipe. A multi-stage drill pipe connector is disclosed that allows contact of electrical contacts at the ends.

Further, in Patent Document 2, a power receiving coil is provided at one end of the drill pipe so that power can be transmitted more stably than the electrical contacts disclosed in Patent Document 1 at the joint of the drill pipe. Disclosed is a drill pipe multi-stage connector capable of non-contact power transmission at a joint of a drill pipe by providing a power transmission coil at the other end and connecting them with a line in the drill pipe. There is.

In Patent Document 2, in order to reduce a decrease in transmission efficiency at the joint of the drill pipe, in the vicinity of the power receiving coil and the power transmitting coil, between the metal drill pipe main body and the power receiving coil and between the drill pipe main body and the power transmitting coil. Discloses a structure in which a cylindrical sheet made of a copper-based metal or an aluminum-based metal and a cylindrical sheet made of ferrite, which have a higher conductivity than that of a drill pipe body, are provided.

Special Table 2003-53132 No. JP-A-2018-148784

However, in a multi-stage drill pipe connection, it is desirable to increase the power transmission efficiency or widen the frequency band in which power can be transmitted so that many drill pipes can be connected in multiple stages.

The present invention has been made in view of the above circumstances, and an object of the present invention is to increase the power transmission efficiency in a drill pipe multi-stage connection capable of transmitting power in a non-contact manner at a joint of the drill pipes. Another object of the present invention is to provide a drill pipe multi-stage connector in which a frequency band in which power can be transmitted is widened.

In order to achieve the above object, the drill pipe multi-stage connection according to claim 1 is provided with a power receiving coil at one end of the drill pipe main body forming the drill pipe and a power transmitting coil at the other end. In a drill pipe multi-stage connection body in which the power receiving coil and the power transmitting coil are connected by a line and the drill pipe is connected in multiple stages, the power receiving coil is a spiral coil and is attached to the one end of the drill pipe body. A high conductivity metal body which is arranged in the formed annular groove and whose conductivity is higher than that of the drill pipe body is arranged between the bottom surface and both side surfaces of the groove and the power receiving coil, and the magnetic body is the magnetic material. Arranged between the high conductivity metal body and the power receiving coil and on the opening side of the groove of the power receiving coil, the power transmitting coil is a spiral coil and is formed at the other end of the drill pipe body. A high conductivity metal body arranged in the annular groove and having a higher conductivity than that of the drill pipe body is arranged between the bottom surface and both side surfaces of the groove and the transmission coil, and the magnetic body has the high conductivity. It is arranged between the metal body and the power transmission coil and on the opening side of the groove of the power transmission coil.

The drill pipe multi-stage connection according to claim 2 is the drill pipe multi-stage connection according to claim 1, wherein the magnetic material in the groove formed at the one end of the drill pipe main body is a magnetic material. The power receiving coil is embedded so as to be hermetically sealed, and the magnetic material in the groove formed at the other end of the drill pipe body is embedded so as to hermetically seal the power transmitting coil.

The drill pipe multi-stage connection according to claim 3 is the drill pipe multi-stage connection according to claim 1. In the drill pipe multi-stage connection, the magnetic material in the groove formed at the one end of the drill pipe main body is It is a box-shaped object with a lid, and the magnetic material in the groove formed at the other end of the drill pipe body is a box-shaped object with a lid.

The drill pipe multi-stage connection according to claim 4 is the drill pipe multi-stage connection according to claim 3, wherein the magnetic material in the groove formed at the one end of the drill pipe main body is a magnetic material. Further, it is also provided between the lines of the power receiving coil, and the magnetic material in the groove formed at the other end of the drill pipe body is further provided between the lines of the power transmitting coil. There is.

According to the drill pipe multi-stage connector of the present invention, in a device capable of transmitting power in a non-contact manner at a joint of drill pipes, the power transmission efficiency can be improved and the frequency band in which power can be transmitted is widened. Can be done.

It is a side view sectional view which shows the drill pipe multi-stage connection body which concerns on embodiment of this invention, (a) shows one drill pipe and a part of the drill pipe on both sides, (b) is one drill. It shows only the pipe. It is a side view cross-sectional view which shows the vicinity of the joint of the drill pipe of the above-mentioned drill pipe multi-stage connection body, (a) is enlarged and (b) is further enlarged, and shows the aspect in a magnetic material. .. It is a side view cross-sectional view which shows another aspect in the magnetic body of the drill pipe of the same-mentioned drill pipe multi-stage connection body, (a) is a box-shaped magnetic material with a lid, (b) is a magnetic material. Further, it is also provided between the wires of the coil. The configuration of the simulation of the drill pipe multi-stage connection body as described above is shown, where (a) is a side sectional view and (b) is a circuit block diagram. It is a characteristic graph of the result of the simulation of the drill pipe multi-stage connection body of the same as above, and the mode of the magnetic material is changed. It is a side view sectional view which shows the aspect of the comparative example of the simulation in the magnetic body of the drill pipe of the same-mentioned drill pipe multi-stage connection body. It is a characteristic graph of the result of the simulation of the drill pipe multi-stage connection body of the same as above, and the relative magnetic permeability is changed.

Hereinafter, modes for carrying out the present invention will be described. As shown in FIG. 1A, the drill pipe multi-stage connection body 1 according to the embodiment of the present invention is a multi-stage connection of the drill pipe 2.

As shown in FIGS. 1 (a) and 1 (b), the drill pipe 2 is formed of a hard drill pipe main body 3. For example, the drill pipe multi-stage connector 1 is controlled by a machine installed on a research vessel floating in the ocean or the like, and the drill pipe main body 3 serves as a power transmitter for excavating the bottom of the water. The drill pipe main body 3 is made of metal, for example, and is usually made of iron-based metal. Further, the drill pipe main body 3 has a hollow hole 30 in the longitudinal direction (vertical direction in the drawing) through which seawater or the like flows. In addition, in FIGS. 1A, 1B, etc., the drill pipe main body 3 is shown by enlarging the radial direction as compared with the longitudinal direction for convenience of illustration, but for example, the longitudinal direction is about 10 m in diameter. Can be about 15 cm to 20 cm.

The drill pipe 2 is typically connected to the other drill pipe 2 by forming a screw at one end 3a and the other end 3b of the drill pipe body 3. In the present embodiment, a female screw is formed on one end 3a and a male screw is formed on the other end 3b, but a male screw may be formed on one end 3a and a female screw may be formed on the other end 3b. Further, the shape and size of the screw can be appropriately determined according to the usage environment of the drill pipe multi-stage connector 1 and the like.

Further, as shown in FIG. 2A, the drill pipe 2 has an annular groove 3aa formed at one end 3a of the drill pipe main body 3 and an annular groove 3ba formed at the other end 3b. The annular grooves 3aa and 3ba are formed around the hollow hole 30 of the drill pipe main body 3. A part of the drill pipe main body 3 3ab and 3bb is annular between the annular grooves 3aa and 3ba and the hollow hole 30.

As shown in FIG. 2A, the drill pipe 2 is provided with a power receiving coil 4 at one end 3a of the drill pipe main body 3 and a power transmission coil 5 at the other end 3b. The power receiving coil 4 and the power transmitting coil 5 are connected by a line 6.

Both the power receiving coil 4 and the power transmitting coil 5 are spiral coils. A spiral coil is a coil formed by winding an electric conducting wire in a flat spiral shape.

The power receiving coil 4 is arranged in the annular groove 3aa formed in one end 3a of the drill pipe body 3, and the power transmission coil 5 is formed in the other end 3b of the drill pipe body 3. It is arranged in the annular groove 3ba.

Further, in the vicinity of the power receiving coil 4, as shown in FIG. 2B, a highly conductive metal body 4A is arranged between the bottom surface and both side surfaces of the annular groove 3aa and the power receiving coil 4. The magnetic body 4B is arranged between the high conductivity metal body 4A and the power receiving coil 4 and on the opening side of the groove 3aa of the power receiving coil 4. Further, in the vicinity of the power transmission coil 5, a high conductivity metal body 5A is arranged between the bottom surface and both side surfaces of the annular groove 3ba and the power transmission coil 5, and the magnetic body 5B is a high conductivity metal body 5A. It is arranged between the power transmission coil 5 and the opening side of the groove 3ba of the power transmission coil 5. The high conductivity metal bodies 4A and 5A have higher conductivity than the drill pipe main body 3. The high conductivity metal bodies 4A and 5A are made of, for example, a copper-based metal or an aluminum-based metal. The magnetic bodies 4B and 5B are made of ferrite, for example.

As a specific embodiment, the magnetic body 4B can embed the power receiving coil 4 as shown in FIG. 2 (b). In this case, the magnetic material 4B can be manufactured by putting the raw material in a mold and sintering the power receiving coil 4 in a state of being embedded in the mold. Similarly, the magnetic body 5B can also embed the power transmission coil 5 as a specific embodiment. In this case, the magnetic body 5B can also be manufactured in the same manner as the magnetic body 4B.

As a specific alternative aspect, the magnetic material 4B can be made into a box shape with a lid as shown in FIG. 3 (a). Similarly, the magnetic material 5B can be made into a box-shaped one with a lid as a specific alternative aspect. Further, in addition to being a box-shaped magnetic material 4B with a lid, as shown in FIG. 3B, the magnetic material 4B is also provided between the lines of the power receiving coil 4 (between the electric conducting wires), and the magnetic material 5B is provided. Can be provided between the lines of the power transmission coil 5 in addition to the box shape with a lid.

The line 6 is usually composed of two conductors as schematically shown in FIGS. 1 (a) and 1 (b), and for example, one end of one conductor is attached to one end of the power receiving coil 4 and the other. Is connected to one end of the power transmission coil 5, one end of the other conductor is connected to the other end of the power receiving coil 4, and the other end is connected to the other end of the power transmission coil 5 (FIG. 2 (FIG. 2). a) See). A shielded cable such as a coaxial cable can be used for the line 6. The wiring method in the drill pipe 2 is not particularly limited in the line 6, but for example, in one end 3a and the other end 3b of the drill pipe main body 3, from the groove 3aa and the groove 3ba. A passage (not shown) having an inner diameter corresponding to the line 6 is formed inside the drill pipe main body 3 up to the hollow hole 30 and is passed through the passage, and most of the rest is along the inner wall of the hollow hole 30. be able to. It is also possible to form a linear groove into which the line 6 enters the inner wall of the hollow hole 30. Alternatively, for example, at one end 3a and the other end 3b of the drill pipe body 3, the line 6 is inside the drill pipe body 3 until it reaches the outer surface of the drill pipe body 3 from the groove 3aa and the groove 3ba. A passage having a narrow inner diameter can be formed according to the above, and most of the other passages can be made along the outer surface of the drill pipe main body 3. It is also possible to form a linear groove into which the line 6 enters on the outer surface of the drill pipe main body 3. If necessary, the inner wall of the narrow passage and the line 6 are sealed so as not to allow seawater or the like to pass therethrough.

In the drill pipe multi-stage connection body 1 in which the drill pipes 2 having the above-described configuration are connected in multiple stages, the power receiving coil 4 of the drill pipe 2 does not physically contact the power transmission coil 5 of the adjacent drill pipe 2 and magnetically. Join. As a result, electric power is also transmitted at the joint between the drill pipes 2 in the drill pipe multi-stage connection body 1.

Since the drill pipe main body 3 is usually made of iron-based metal, the magnetic flux generated around the power receiving coil 4 and the power transmitting coil 5 causes a large loss due to current flowing. The high conductivity metal bodies 4A and 5A can prevent the magnetic flux from leaking to the drill pipe main body 3. In the high conductivity metal bodies 4A and 5A, even if a current is induced near the surface of the power receiving coil 4 or the power transmission coil 5, the loss is small due to the high conductivity.

The magnetic bodies 4B and 5B can reduce the magnetic flux leaking to the high conductivity metal bodies 4A and 5A by attracting the magnetic flux, and can further reduce the loss due to the high conductivity metal bodies 4A and 5A.

Further, the magnetic bodies 4B and 5B are arranged on the opening side of the groove 3aa of the power receiving coil 4 and the opening side of the groove 3ba of the power transmission coil 5, respectively (details are shown in FIGS. 2B and 5B of the magnetic bodies 4B and 5B). A mode in which the power receiving coil 4 and the power transmitting coil 5 are embedded as shown in FIG. 3, a mode in which the magnetic bodies 4B and 5B are shaped like a box with a lid as shown in FIG. As shown in FIG. 3B, the shape is a box with a lid, and the power receiving coil 4 and the power transmitting coil 5 are provided between the lines of the power receiving coil 4 and the power transmitting coil 5). The magnetic flux generated around the coil 5 is increased to increase the transmission efficiency of the power transmitted in the drill pipe multi-stage connector 1 as shown in the simulation described later, and the frequency band in which the power can be transmitted is increased. It can be made to spread.

Further, the influence on the power transmission efficiency and the frequency band when seawater or the like flows through the hollow hole 30 of the drill pipe main body 3 is that the above-mentioned drill pipe main body 3 is between the hollow hole 30 and the magnetic materials 4B and 5B. Since there are a part of 3ab and 3bb and high conductivity metal bodies 4A and 5A, the amount is greatly reduced.

Further, although it is possible to use a solenoid coil for both the power receiving coil 4 and the power transmitting coil 5, it is easy to form grooves 3aa and 3ba and it is easy to obtain a large magnetic coupling with each other, as described above. It is preferable to use a spiral coil.

Further, the power receiving coil 4, the magnetic body 4B, and the high conductivity metal body 4A can be unitized into a power receiving unit, and the power transmission coil 5, the magnetic body 5B, and the high conductivity metal body 5A can be unitized into a unit. It can be a power transmission unit. Further, the magnetic body 4B and the high conductivity metal body 4A can be provided with an insulating protective layer on the side facing the magnetic body 5B and the high conductivity metal body 5A, and the magnetic body 5B and the high conductivity metal body 4A can be provided with an insulating protective layer. The metal body 5A can be provided with an insulating protective layer on the side facing the magnetic body 4B and the high conductivity metal body 4A.

Next, a simulation performed by the inventor of the present application of power transmission in the drill pipe multi-stage connector 1 will be described. An electromagnetic field simulator and a circuit simulator were used for the simulation. In this simulation, as shown in FIG. 4A, the drill pipe multi-stage connection 1 has three joints of the drill pipe 2. As the drill pipe main body 3, a 10 m iron one was used. As the power receiving coil 4 and the power transmitting coil 5, the electric conducting wire was made of copper and had a diameter of 0.5 mm, the distance between the wires was 0.1 mm, and 6 turns were used. The high conductivity metal bodies 4A and 5A were made of aluminum having a thickness of 0.5 mm, and were separated from the power receiving coil 4 and the power transmission coil 5 by 0.25 mm. The magnetic materials 4B and 5B used were made of ferrite (specific magnetic permeability μ'is 130 or 500, loss coefficient tan δ is 0.01). Line 6 used a 3D2V coaxial cable.

When the simulation configuration of the drill pipe multi-stage connector 1 is represented by a circuit block diagram, the unit circuit 7 is connected in three stages as shown in FIG. 4 (b). The unit circuit 7 is composed of a wiring unit 8, a coil coupling unit 9, and a wiring unit 8. The wiring portion 8 represents the electrical characteristics of half of the total length of the line 6 of the drill pipe 2, and the coil coupling portion 9 represents the electrical characteristics of the coupled power transmission coil 5 and power receiving coil 4. It is a part. In the figure, L ₁ and R ₁ are the inductance component and the resistance component of the power transmission coil 5, L ₂ and R ₂ are the inductance component and the resistance component of the power reception coil 4, and M is between the power transmission coil 5 and the power reception coil 4. Mutual inductance of. In the simulation, the power transmitted to the _{terminating resistor Z L} when the AC voltage E is applied to the three-stage unit circuit 7 is examined. The terminating resistor Z _L was set to 1 kΩ.

5 and 7 show the simulation results for the transmission efficiency η. The horizontal axis f is the frequency of the electric power transmitted to the drill pipe multi-stage connector 1, and the vertical axis η is the ratio of the electric power transmitted up to the _{terminating resistor Z L (that is, the transmission efficiency).}

FIG. 5 shows a simulation in which the modes of the magnetic bodies 4B and 5B are changed while the relative magnetic permeability μ'of the magnetic bodies 4B and 5B is set to a constant 130. The curve a in the figure shows a mode in which the power receiving coil 4 and the power transmitting coil 5 are embedded in the magnetic bodies 4B and 5B as shown in FIG. The curve b is an embodiment in which the magnetic bodies 4B and 5B are shaped like a box with a lid as shown in FIG. 3B, and are also provided between the lines of the power receiving coil 4 and the lines of the power transmission coil 5. belongs to. The curve c is a form in which the magnetic bodies 4B and 5B are shaped like a box with a lid as shown in FIG. 3 (a). The curve d is a comparative example, in which the magnetic bodies 4B and 5B are arranged only on the bottom surface and the inside of both side surfaces of the annular grooves 3aa and 3ba as shown in FIG.

From FIG. 5, the curve a shows the maximum transmission efficiency of about −0.32 dB when the frequency is about 0.48 MHz, and as the frequency increases from about 0.48 MHz to 1 MHz, the transmission efficiency approaches the maximum. It is gently falling. The curve b shows the maximum transmission efficiency of about -0.57 dB when the frequency is about 0.80 MHz, and as the frequency rises from about 0.80 MHz to 1 MHz, the transmission efficiency is maintained near the maximum value and then gently. It's down. The curve c maintains a frequency of about 0.80 MHz to 1 MHz with a maximum transmission efficiency of about −0.60 dB. The curve d has a maximum transmission efficiency of about −0.60 dB when the frequency is about 0.80 MHz, and the transmission efficiency drops sharply at frequencies above and below that.

Therefore, in the case where the power receiving coil 4 and the power transmitting coil 5 are embedded in the magnetic bodies 4B and 5B as shown in FIG. 2, as shown by the curve a, the electric power is applied at a frequency of about 0.48 MHz to 1 MHz. It can be seen that the transmission efficiency of electric power can be greatly increased by transmission. Further, since the transmission efficiency is close to the maximum in a wide frequency range, it can be seen that the frequency band in which electric power can be transmitted can be widened. When the frequency band in which electric power can be transmitted is widened, even if the number of stages of the drill pipe multi-stage connector 1 is increased, the frequency of the transmitted electric power fluctuates, or the characteristics of each drill pipe 2 vary. It facilitates long-distance transmission of electric power.

Further, in the case where the magnetic bodies 4B and 5B are shaped like a box with a lid as shown in FIG. 3B, and are also provided between the lines of the power receiving coil 4 and the lines of the power transmission coil 5. As shown by the curve b, it can be seen that the power transmission efficiency can be increased when the frequency is from about 0.80 MHz to about 1 MHz. Further, since the transmission efficiency is close to the maximum in a wide frequency range, it can be seen that the frequency band in which electric power can be transmitted can be widened.

Further, in the case where the magnetic bodies 4B and 5B are in the shape of a box with a lid as shown in FIG. 3A, the transmission efficiency is close to the maximum in a wide frequency range as shown by the curve c. It can be seen that the frequency band in which power can be transmitted can be expanded.

In FIG. 7, in a mode in which the power receiving coil 4 and the power transmitting coil 5 are embedded in the magnetic bodies 4B and 5B as shown in FIG. 2, the relative magnetic permeability μ'of the magnetic bodies 4B and 5B is changed to 130 and 500. This is a simulation. The curve a'in FIG. 7 is a case where the relative permeability μ'is 130. The curve e in FIG. 7 is a case where the relative magnetic permeability μ'is 500.

From FIG. 7, the curve e has a maximum transmission efficiency of about −0.16 dB when the frequency is about 0.27 MHz, and approaches the maximum as the frequency increases from about 0.27 MHz to about 0.48 MHz. The transmission efficiency is gradually decreasing. Therefore, it can be seen that when the relative magnetic permeability μ'of the magnetic materials 4B and 5B is increased, the range of the frequency band that can be transmitted is slightly reduced, but the transmission efficiency is increased when the magnetic materials 4B and 5B are shifted to the low frequency side.

Although the drill pipe multi-stage connection according to the embodiment of the present invention has been described above, the present invention is not limited to the one described in the above-described embodiment, but is within the scope of the claims. Various design changes are possible. For example, the dimensions of the power receiving coil and the power transmitting coil, the magnetic material around them, the high conductivity metal body, and the like can be set in various ways. Further, the drill pipe multi-stage connection according to the embodiment of the present invention can be used for various purposes (for example, excavation of a mine) in addition to the purpose of excavating the seabed.

1 Drill pipe multi-stage connector 2 Drill pipe 3 Drill pipe body 3a One end of the drill pipe 3 aa Circular groove formed at one end of the drill pipe 3ab Part of the ring at one end of the drill pipe 3b The other end of the drill pipe 3ba An annular groove formed at the other end of the drill pipe 3bb Part of the ring at the other end of the drill pipe 30 Hollow hole in the body of the drill pipe 4 Power receiving coil 4A Around the power receiving coil High conductivity metal body 4B Magnetic material around the power receiving coil 5 Transmission coil 5A High conductivity metal body around the power transmission coil 5B Magnetic material around the power transmission coil 6 Line 7 Unit circuit 8 Unit circuit wiring 9 Unit circuit Coil coupling part E AC voltage L ₁ Transmission coil inductance component R ₁ Transmission coil resistance component L ₂ Power receiving coil inductance component R ₂ Power receiving coil resistance component M Mutual inductance between the power transmitting coil and power receiving coil Z _L Termination resistance

Claims (4)

A power receiving coil is provided at one end of the drill pipe body forming the drill pipe, a power transmitting coil is provided at the other end, and the drill pipe in which the power receiving coil and the power transmitting coil are connected by a line is connected in multiple stages. In the drill pipe multi-stage connection
The power receiving coil is a spiral coil, and a highly conductive metal body having a higher conductivity than that of the drill pipe body is arranged in an annular groove formed at one end of the drill pipe body. The bottom surface and both side surfaces of the groove are arranged between the power receiving coil, and the magnetic material is arranged between the high conductivity metal body and the power receiving coil and on the opening side of the groove of the power receiving coil.
The power transmission coil is a spiral coil, and a highly conductive metal body having a higher conductivity than that of the drill pipe body is arranged in an annular groove formed at the other end of the drill pipe body. A drill pipe arranged between the bottom surface and both side surfaces of the groove and the transmission coil, and the magnetic material is arranged between the high conductivity metal body and the transmission coil and on the opening side of the groove of the transmission coil. Multi-stage connector. In the drill pipe multi-stage connection according to claim 1,
The magnetic material in the groove formed at the one end of the drill pipe body is embedded so as to seal the power receiving coil.
The magnetic material in the groove formed at the other end of the drill pipe main body is a drill pipe multi-stage connection body in which the power transmission coil is embedded so as to seal the transmission coil. In the drill pipe multi-stage connection according to claim 1,
The magnetic material in the groove formed at the one end of the drill pipe body is a box-shaped material with a lid.
The magnetic material in the groove formed at the other end of the drill pipe body is a box-shaped drill pipe multi-stage connection body with a lid. In the drill pipe multi-stage connection according to claim 3,
The magnetic material in the groove formed at the one end of the drill pipe body is further provided between the lines of the power receiving coil.
The magnetic material in the groove formed at the other end of the drill pipe body is a drill pipe multi-stage connection body further provided between the lines of the power transmission coil.

Images