JPH0350994B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides for transporting fluids such as gas, tap water, etc.
The present invention also relates to a device for preventing damage to metal pipes buried underground to protect power lines and the like.

Such metal underground pipes are generally galvanically protected. In order to check the operating status of this electrolytic corrosion protection, it is necessary to drill a hole in the ground near the underground pipe, insert an electrode into the drilled hole, and check the corrosion protection status. The hole to be drilled using this electrode is placed close to the underground pipe, for example, up to 10 cm, and therefore, when drilling with the drill, the drill may damage the underground pipe. There is a risk of destruction. When excavating soft soil with a drill, the operator may be able to relatively easily tell by feel when the tip of the drill comes into contact with an underground pipe. However, when an underground pipe is laid beneath a concrete layer and the concrete layer is being excavated with a drill, even if the tip of the drill comes into contact with the underground pipe, the worker may not be able to feel the contact. Therefore, the underground pipe may be destroyed.

An object of the present invention is to provide a device that can reliably prevent damage to underground pipes.

The present invention provides an AC power supply 9 and a first output terminal connected to one output terminal of the AC power supply 9.
an electric drill 5 driven by power supplied through the line 10 and a second line 18 connected to the other output terminal of the AC power source 9; and rectifying the power from the output terminal of the AC power source 9. a pair of third rectifier circuits for deriving the rectified output of the rectifier circuit 19;
and the fourth line 20, 21, and the first line, which performs the conduction/cutoff operation in conjunction with each other.
The latching relay 16 has the second and third switches 12, 22, 27, the first and second windings 31, 32, and the relay switch 17, the first and second windings 31, 32 are commonly connected to the third line 20, and the excitation of the first winding 31 keeps the relay switch 17 in the cut-off state, and the excitation of the second winding 32 keeps the relay switch 17 in the cut-off state. It includes such a latching relay 16 to maintain conduction, and a buzzer 8 connected between the third line 20 and the third switch 27, and the other output terminal of the AC power source 9 and the second line 18. A first switch 12 is interposed between the two, a relay switch 17 is interposed between the second line 18, a second switch 22 is interposed between the fourth line 21 and the second winding 32, and the second switch 22 is interposed between the fourth line 21 and the second winding 32. A starting switch 33 is interposed between the first winding 31 and the second winding 32 to temporarily conduct electricity and excite the second winding 32, and the other end of the first winding 31 and the third switch 27 are connected. Further, the connection point between the buzzer 8 and the third switch 27 is connected to either the underground metal pipe 3 or the electric drill 5 via a fifth line 29, and the connection point between the second switch 22 and the starting switch 33 is connected to either the electric drill 5 or the underground metal pipe 3 via the sixth line 34, which is an underground pipe damage prevention device.

FIG. 1 is a sectional view showing a working state of an embodiment of the present invention. A metal pipe 2 for supplying city gas is buried in the ground 1. The gas from the pipe 2 is passed from the pipe 3 to the gas meter 4 and is used in each household. In order to check the corrosion-protected state of the pipes 2 and 3, a hole 6 is drilled near the pipe 3 using an electric drill 5. During this excavation, the tip 7 of the electric drill 5 may come into contact with the pipe 3 and damage the pipe 3. In order to prevent the tip 7 of the electric drill from damaging the tube 3, according to one embodiment of the invention, an alarm sound is generated when the tip 7 of the electric drill 5 contacts the tube 3.

FIG. 2 is an electrical circuit diagram of one embodiment of the present invention. Electric power from the commercial AC power supply 9 is supplied via a first line 10 and from a line 11 to the first line 10.
The latching relay 16 is connected from the line 15 via the contact 13 of the switch 12 to the contact 14.
Power is supplied via a relay switch 17 and via a second line 18.
The AC power from this power source 9 is rectified by a rectifier circuit 19, and its DC output is led out to lines 20 and 21, which are the third and fourth lines. The line 20 is connected to one end of a buzzer 8 as an alarm display means. Line 21 is connected to an individual contact 23 of a second switch, changeover switch 22.
A common contact 24 of the switch 22 is connected to an individual contact 25. Individual contacts 25 are connected to one end of a portable power source 26, such as a battery. The other end of power supply 26 is connected to line 20. A contact 28 of another switch 27, which is a third switch, is connected to the other end of the buzzer 8, and is connected to the above-mentioned exposed part 3a of the metal underground pipe 3 through a line 29, which is a fifth line. connected to.

A contact 30 of the switch 27 is connected to one relay coil 31, which is the first winding of the latching relay 16. Another coil 32, which is the second winding of the latching relay 16, is connected to a starting switch 33.
It is connected to the common contact 24 of the changeover switch 22 via. Coils 31 and 32 are commonly connected to line 20. The latching relay 16 switches the relay switch 17 when the relay coil 31 is energized.
Even if the relay coil 31 is subsequently demagnetized, the relay switch 17 remains in the cut-off state. Furthermore, when the relay coil 32 is excited, the relay switch 17 becomes conductive, and then the relay coil 3
Even when the relay switch 2 is demagnetized, the conductive state of the relay switch 17 is maintained.

The switches 12, 22, and 27 change their switching modes in conjunction with each other. Common contact 2 of switch 22
4 is connected to the electric drill 5 via a line 34, which is a sixth line. The electric drill 5 is made of metal, and when its tip 7 contacts the pipe 3, the lines 29 and 34 are electrically connected.

The electric drill 5 is powered by the power from the AC power source 9.
To energize, switches 12 and 27 are brought into conduction, and common contact 24 of switch 22 remains conductive to individual contact 23. When the relay switch 17 of the latching relay 16 is disconnected, the starting switch 33 is temporarily turned on to excite the relay coil 32, thereby keeping the relay switch 17 conductive. Thus line 1
Power is supplied to the electric drill 5 from 0,18,
It is possible to drill a hole 6.

When the tip 7 of the electric drill 5 comes into contact with the pipe 3, the lines 29 and 34 become electrically connected. As a result, the buzzer 8 has a line 21 and an individual contact 2 of the switch 22.
3. Electric power is supplied through the common contact 24, the line 34, the electric drill 5 and its tip 7, the pipe 3 and the line 29, and the buzzer 8 sounds. In this way, the buzzer 8 sounds only while the tip 7 of the electric drill 5 is in contact with the pipe 3.

When the tip 7 of the electric drill 5 comes into contact with the pipe 3, the power from the rectifier circuit 19 is transferred from the relay coil 31 of the latching relay 16 to the contacts 30 and 28 of the switch 27, the line 29, the pipe 3, and the electric drill 5. A current flows through the tip 7, the line 34, the common contact 24 of the switch 22, the individual contacts 23, and the line 21, and the relay coil 31 is energized.
This shuts off the relay switch 17.
Even after the tip 7 of the electric drill is separated from the pipe 3, the latching relay 16 remains in contact with the relay switch 17.
maintain the cut-off state. In this way, electric drill 5
Once the tip 7 of the electric drill 5 contacts the pipe 3, the electric drill 5 immediately remains deenergized and drilling is no longer possible. The pipe 3 is thus prevented from being damaged by the electric drill 5.

The present invention is applicable not only to metal underground pipes for transporting city gas, but also to metal underground pipes transporting other fluids, and metal underground pipes protecting power lines, etc. It is also possible to implement the above.

In this embodiment, the line 29 is connected to the pipe 3 and the line 34 is connected to the electric drill 5, but the line 29 is connected to the electric drill 5 and the line 34 is connected to the pipe 3. Of course, it is possible.

As described above, according to the present invention, when the electric drill 5 comes into contact with the underground metal pipe 3 during excavation work, the buzzer 8 is activated and the power supply to the electric drill 5 is cut off. , the work can be stopped immediately to prevent damage to underground metal pipes.

Further, according to the present invention, the latching relay 16,
Rectifier circuit 19, first to third switches 12, 22,
27, the simple configuration including the start switch 33 and the first to sixth lines 10, 18, 20, 21, 29, 34, etc. can prevent damage to the underground metal pipe. Since such a configuration does not include an electronic circuit that is susceptible to noise or the like, there is little risk of malfunction even when used with the electric drill 5.

Further, according to the present invention, (a) the buzzer 8 is activated only when the electric drill 5 is in contact with the underground metal pipe 3, and (b) power is supplied to the electric drill 5 from the underground metal pipe 3. If the electric drill 5 contacts 3 even once, it will be stopped. As a result, underground metal pipe 3
The presence or absence of contact between the electric drill 5 and the electric drill 5 can be confirmed even after the electric drill 5 has stopped, without increasing the damage, only by hearing from the buzzer 8, without visual inspection.

In addition, the first to third switches 12, 22,
27 can control the power supply to each of the electric drill 5, the buzzer 8, and the first winding 31 of the latching relay 16 by simultaneously turning on/off the electric power. With this, when using the electric drill 5, it is possible to simply switch the first to third switches 12, 22, 2.
By operating 7, it is possible to reliably prevent damage.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a state in which a hole 6 is drilled in the ground 1 by an electric drill 5, and FIG. 2 is an electric circuit diagram of an embodiment of the present invention. 2, 3... Metal underground pipe, 3a... Exposed part, 5... Electric drill, 6... Hole, 8... Buzzer, 12, 27, 22... Switch, 16... Latching relay, 19... Rectifier circuit, 33... Start switch.

Claims (1)

[Claims] 1 AC power supply 9; a first terminal connected to one output terminal of the AC power supply 9;
an electric drill 5 driven by power supplied through the line 10 and a second line 18 connected to the other output terminal of the AC power source 9; and rectifying the power from the output terminal of the AC power source 9. a pair of third rectifier circuits for deriving the rectified output of the rectifier circuit 19;
and the fourth line 20, 21, and the first line, which performs the conduction/cutoff operation in conjunction with each other.
The latching relay 16 has the second and third switches 12, 22, 27, the first and second windings 31, 32, and the relay switch 17, the first and second windings 31, 32 are commonly connected to the third line 20, and the excitation of the first winding 31 keeps the relay switch 17 in the cut-off state, and the excitation of the second winding 32 keeps the relay switch 17 in the cut-off state. It includes such a latching relay 16 to maintain conduction, and a buzzer 8 connected between the third line 20 and the third switch 27, and the other output terminal of the AC power source 9 and the second line 18. A first switch 12 is interposed between the two, a relay switch 17 is interposed between the second line 18, a second switch 22 is interposed between the fourth line 21 and the second winding 32, and the second switch 22 is interposed between the fourth line 21 and the second winding 32. A starting switch 33 is interposed between the first winding 31 and the second winding 32 to temporarily conduct electricity and excite the second winding 32, and the other end of the first winding 31 and the third switch 27 are connected. Further, the connection point between the buzzer 8 and the third switch 27 is connected to either the underground metal pipe 3 or the electric drill 5 via a fifth line 29, and the connection point between the second switch 22 and the starting switch 33 is connected to the other of the electric drill 5 or the underground metal pipe 3 via a sixth line 34.