JPH0222602B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pipe joint having waterproof and dustproof properties, and specifically relates to an improvement of a pipe joint for a conduit through which a cable is passed.

[Conventional technology]

When wiring equipment such as motors and measuring instruments that are used outdoors where they are exposed to wind and rain or in other environments where adverse conditions are expected, conductive wires and Conduit pipes that cover these conductors are often hung horizontally from the bottom end, and rainwater and dust can enter the inside of the equipment at the wiring outlet located below the cable duct, operation box, etc. In order to prevent the intrusion of electrical conductors and to protect the conducting wires, conduits and pipe joints such as those shown in FIG. 5 are used, for example.

To explain this, in FIG. 5, 1 is a cylindrical joint body (ground) that is tightened to the exterior of a device (not shown), 2 is a conduit connected to the joint body 1, and 3 is a conduit 2. This is a nut for coupling to the joint body 1.

The electrical conduit 2 has a tube body 2a formed by spirally winding a thin band-shaped metal plate, and a coating 2 such as vinyl.
b, and the spiral structure of the tube body 2a gives it flexibility, so that it can be bent freely according to the routing of a cable (not shown) that penetrates the inside. A bushing 4 is fitted into the end of the conduit 2, which is formed by pressing a metal plate or the like to cover the inside and outside of the tube end.
The tip of this bush 4 is connected to the large diameter opening 1 of the joint body 1.
When the nut 3 is tightened with the nut 3 inserted in
is compressed and deformed, and the tightening force of the nut 3 is applied between the joint body 1 and the annular bushing 4 to firmly connect the conduit 2 to the joint body 1, and also to tighten the connection between the nut 3 and the joint body 1. Demonstrates waterproof and dustproof sealing function between. Also, at this time, the joint body 1
Since the wire and the conduit main body 2a constitute a conductive path via the bush 4, it is possible to take measures such as grounding as necessary. (As a known example of this type of pipe joint structure, for example, Utility Model Application Publication No. 53-65593
See Japanese Utility Model Publication No. 57-8230. ) Furthermore, Japanese Utility Model Application Publication No. 47-17198 discloses an outer packing inserted between the nut and the bushing, and an outer packing inserted between the joint body and the bushing, which is placed closer to the equipment than this packing. A pipe joint is shown in which the bushing and the outer and inner packings are tightened toward the joint body by tightening the nut onto the joint body.

[Problem that the invention seeks to solve]

However, with the structure of the conventional joint pipe shown in Figure 5, rainwater, etc. that flows down the outer circumferential surface of the hanging part of the conduit between the cable duct at a high place and the equipment below is transmitted to the pipe joint. Although the rubber gasket can prevent rainwater from entering the conduit joint from the connection part provided at the hanging part of the conduit, it may prevent rainwater from entering the conduit or condensation on the inner circumferential surface of the conduit. If this occurs, this water may be guided from the hanging part to the lower end of the conduit and accumulate, entering the pipe joint, causing aging and corrosion of conductors such as conduits and cables, and various parts of the pipe joint. Otherwise, rainwater or condensation water may be led from inside the pipe joint to the equipment, causing a short circuit.

In the conventional pipe joint using the above-mentioned outer packing and inner packing, by crimping the inner circumferential surface of the inner packing to the outer circumferential surface of the cable, it accumulates at the lower end of the conduit and between the cable and the fitting. This can prevent water that has entered the gap from being led to the equipment side, but since the accumulated water cannot be drained out, the inner packing is likely to age, and since the inner packing can only be compressed in the axial direction, the outer diameter There was a problem in that a single type of pipe joint could not handle a plurality of different types of cables, and many different types of pipe joints were required.

In the conventional pipe joint as shown in FIG. 5, when the nut 3 is tightened to the joint body 1, a strong frictional force acts between the nut 3 and the conduit 2 via the rubber packing 5. The rotation of the conduit tube 2 is transmitted and the conduit tube 2 rotates together, and if the other end of the conduit tube 2 is already connected, the conduit tube 2 is twisted and the tube body 2a is damaged.
Alternatively, there was a risk that its durability would deteriorate.
Another problem is that when the tightening progresses to a certain extent, the rubber seal 5 sandwiched between the nut 3 and the bush 4 may be twisted and deformed due to the frictional force exerted on its front and rear end surfaces, resulting in a risk of deterioration of sealing performance. It was hot too.

Further, even with conventional pipe joints that use inner and outer packings, problems such as deformation due to twisting of the packing due to co-rotation of the nut and the outer packing cannot be solved.

The present invention solves the above-mentioned problems of the conventional ones, and even if rainwater enters the gap between the cable and the joint, it is discharged to the outside without accumulating, thereby preventing aging and corrosion of various parts of the joint, such as the inner packing. It is an object of the present invention to provide a conduit joint that can be used for many types of cables having different outer diameters.

In addition to the above-mentioned object, another aspect of the present invention is to
The purpose is to prevent the outer packing from rotating together when tightening the nut, to prevent a decrease in the durability of the outer packing and conduit tubes, and to prevent poor sealing due to twisting or rotation, and to improve the ease of assembly of the joint. There is.

[Means to improve problems]

A conduit joint according to the present invention has a substantially cylindrical joint body coupled to an equipment exterior part, and an outward flange portion having a diameter larger than the outside diameter of a conduit to be connected to the joint body, An insertion portion that fits and secures to the inner diameter portion of the conduit end is formed on one side of the flange portion, and a fitting portion that removably fits into the joint body is formed on the other side. Near the facing flange part, there is a substantially cylindrical bushing with water drain holes provided at multiple locations in the circumferential direction that penetrate the fitting part in the radial direction, and a drain hole is provided from the conduit side to the outward facing flange part of this bushing. A nut that is fitted and has an inward flange facing the end face of the outward flange, and a cylindrical inner side made of an elastic material and interposed between the fitting part of the bush and the joint body. The joint body has a fitting opening portion into which the fitting portion of the bushing fits, and an annular inner step portion protruding inside the fitting opening portion, and the fitting body includes The inner packing is sandwiched between the inner packing and the end face of the fitting part, and the nut is screwed to the outer circumference, and the inner packing is fitted into the fitting opening of the joint body while restraining its diameter from expanding toward the outer circumference. When the nut is tightened into the joint body, the outward flange of the bush approaches the inner step of the joint body, and as a result, the bush is elastically compressed and deformed in the axial direction, flexing and contracting in diameter. is configured to be crimped from inside the conduit to the outer peripheral surface of the cable passing through the bushing and the fitting body, and furthermore, the water drain hole provided in the bushing is opened in an annular gap formed between the end faces of the fitting body and the bushing. It is something.

Another aspect of the present invention provides the above-mentioned electric conduit pipe joint, comprising: a cylindrical outer packing made of an elastic body and interposed between the inward flange of the nut and the outward flange of the bush; A cylindrical part on the joint body side that covers the part of the outer circumferential surface of the outer packing closer to the nut, an annular part sandwiched between the end surface of the outer packing and the inner end surface of the inward flange of the nut, and the inner circumferential surface of the inward flange of the nut and the electrical conduit. and a washer integrally formed with a cylindrical portion inserted between the outer circumferential surface of the

[Effect]

In the conduit joint according to the present invention, when the nut is tightened, the front and rear end surfaces of the inner packing come into close contact with the fitting end surfaces of the bushing and the stepped portion of the joint body, so that there is a gap between the bush and the joint body. A seal is ensured. In other words, the inner packing is
While its diameter expansion is restricted, its inward deformation is free, so when it is tightened, it compresses and deforms at the same time as it flexes and contracts in diameter, allowing it to be inserted from the conduit through the bushing and the fitting body. The axial center of the inner packing is in close contact with the outer circumferential surface of the cable, creating a seal, and even if rainwater gets into the bushing, the water will not be led to the equipment side through the inner packing. In addition, the inner packing is not simply compressed and deformed, but is bent, and the diameter decreases the most at the center in the axial direction, so the amount of deformation in the radial direction can be increased, for example, the outer diameter can be reduced by 5 mm to 8 mm. One type of inner packing is sufficient for different cables, and one type of pipe joint can be used for many types of cables with different outer diameters.

Further, near the outward facing flange of the fitting part provided on the bushing, water drain holes passing through the fitting part in the radial direction are provided at multiple locations in the circumferential direction, and these drain holes are connected to the joint body and the bushing. Since the opening is made in the annular gap between the ends of the cable duct, the connection part of the hanging part of the conduit that connects the cable duct, etc. located at a high place outdoors, and the pipe fitting attached to the equipment located below. Even if rainwater enters the conduit or condenses on the inner circumferential surface of the conduit, and this water is led to the lower end of the conduit, it will pass through the gap between the conduit and the conductor such as a cable, and then enter the bushing. guided by the water drain hole;
It is quickly discharged outside the pipe fitting from a position close to the inner packing through the annular gap and does not accumulate inside the pipe fitting, thereby preventing premature aging of the cable and inner packing and corrosion of the bushing. .

And, another conduit pipe joint according to the present invention is as follows:
When the fitting part of the bushing to which the conduit is fixed is inserted into the fitting opening of the joint body and the nut is tightened, the outer packing sandwiched between the inward flange part of the nut and the outward flange part of the bushing, The inner packing sandwiched between the end face of the fitting portion of the bush and the stepped portion of the joint body simultaneously receives the axial tightening force acting between the nut and the joint body, and is compressed and deformed together.

At this time, the outer packing is in direct contact with the outward flange of the bushing and in close contact with the inward flange of the nut via the annular part of the washer, and is also deformed in the radial direction to tighten the outer surface of the conduit. and is also crimped onto the inner circumferential surface of the cylindrical portion of the joint body side of the washer. Therefore, the gaps between the conduit, nut, and bushing are sealed. In addition, the presence of the annular washer, particularly its annular portion, reduces the frictional force between the end face of the outer packing and the inner flange of the nut, so that the rotation of the nut during tightening is directly transmitted to the outer packing, causing the tightening of the nut. There is no risk of twisting or co-rotation, and ease of assembly is improved. Furthermore, since the bush and the joint body do not rotate relative to each other when tightening the nut, there is no risk of twisting and deforming the inner packing, and the reliability of the seal provided by this packing is increased.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

1A and 1B, 11 is a joint body, 12 is a conduit, 13 is a nut, 14 is a bushing, 15 is an outer packing, 16 is a washer, and 17 is an inner packing. The joint body 11, the nut 13, the bush 14, and the washer 16 are all made of metal materials, and the outer packing 15 and the inner packing 17 are made of metal materials.
is made of an elastic body with relatively high elasticity, such as rubber. Further, the electric conduit 12 is a general type having flexibility by applying a coating 2b of vinyl chloride or the like to a metal tube main body 12a having a spiral structure, similar to the one shown in FIG.

To explain the individual parts in detail, the joint body 11
A small outer diameter portion 11b is located on the left side of the figure across the collar portion 11a on which a tool such as a spanner is applied during tightening.
It has a stepped cylindrical shape with a large outer diameter portion 11c protruding from the right side, and the small outer diameter portion 1c has a stepped cylindrical shape.
1b has a first male threaded portion 11d screwed onto the outer peripheral surface of the device (not shown), and a large outer diameter portion 11c.
A second externally threaded portion 11e into which a nut 13 (to be described later) is screwed is formed on the outer circumferential surface of each of the two. Further, the inner circumferential surface of the main body 11 has a through hole 11f having an inner diameter approximately the same as that of a bush 14 described later on the side of the small outer diameter portion 11b, and an opening 11f having approximately the same inner diameter as the outer diameter of the fitting portion of the bush 14 on the side of the large outer diameter portion 11c. A fitting opening 11g is formed, and an annular step 11h corresponding to the inner diameter difference between the two is formed at the end of the fitting opening 11g on the side of the opening 11f.

On the other hand, as shown in FIG. 2, the bushing 14 has a fitting portion 1 on the left side of the outward flange portion 14a that is removably fitted into the fitting opening portion 11g of the joint body.
4b has a substantially cylindrical shape with an insertion portion 14c that fits into the inner diameter portion of the tube end of the electric conduit 12 on the right side. The outer diameter of the flange portion 14a is approximately the same as the large outer diameter portion 11c of the joint body, and is large enough to fit loosely into the inner diameter portion of the nut 13, and the outer diameter of the insertion portion 14c is approximately the same as the inner diameter of the conduit 12. It is as follows. Furthermore, a protrusion 14d is formed on the outer circumferential surface of the insertion portion 14c at the same pitch as the helical groove 12c of the tube body 12a of the electric conduit 12, and this protrusion 14d and the helical groove 1
2c, the bushing 14 and the conduit 12 are firmly connected. Furthermore, 18 is an outward flange portion 1 of the fitting portion 14b.
These drain holes are formed so as to penetrate in the radial direction near the base portion 4a, and in this embodiment, they are provided in three locations at equal intervals in the circumferential direction.

The nut 13 connects the bush 14 onto which the conduit 12 is screwed as described above to the joint body 11, and has an inward flange portion 13a on the right end side in the figure, through which the conduit 12 passes. At the same time, a female threaded portion 13b is formed on the inner peripheral portion to be screwed into the second male threaded portion 11e of the joint body 11.

The outer packing 15 is approximately cylindrical and is formed to fit around the outer periphery of the conduit 12 without any gaps.
It is interposed between the inward flange 13a of the nut 13 and the outward flange 14a of the bush 14. The cross-sectional shape of the outer packing 15 is a pentagon with a middle height as shown in the figure. The washer 16 is attached to the annular portion 16 as also shown in FIG.
The first cylindrical portion 16b is continuous on the left side of the outer periphery of a,
The respective parts are integrally formed so that the second cylindrical part 16c is continuous on the right side of the inner circumference of the annular part. The right end face and tapered face of the outer packing 15 are connected to the annular part 16a of the washer 16 and the first cylindrical part 16.
b, and the annular portion 16a abuts against the inward flange portion 13a of the nut 13. In addition, this outer packing 15 and nut 13
, before screwing on the bushing 14,
The second cylindrical portion 16c of the washer 16
is the inward flange portion 1 of the conduit 12 and nut 13
3a.

On the other hand, the inner packing 17 has a stepped cylindrical shape as shown in FIG. It is formed by surfaces 17b and 17c and a stepped outer peripheral surface 17d, and the outer peripheral surface 17d
is a small diameter cylindrical surface 17e that has approximately the same outer diameter as the inlet of the main body fitting port 11g and is adjacent to one end surface 17c.
, a large-diameter cylindrical surface 17f having a larger diameter than this and adjacent to the other end surface 17b, and a tapered surface 1 that gradually reduces in diameter from the large-diameter cylindrical surface 17f to a small-diameter cylindrical surface 17e.
7g. This inner packing 17
In this case, the end surface 17b on the large diameter cylindrical surface side is the joint body 1.
The joint body 1 is seated on the inner step 11h of the joint body 1.
1 into the fitting opening 11g. For this purpose, the shape of the fitting opening 11g near the stepped portion 11h is stepped to match the inner packing 17. Further, the inner diameter of the inner circumferential surface 17a of the inner packing 17 in a free state is made as small as possible within a range that does not interfere with the insertion of the cable 19.

FIG. 1A shows the fitting part 14b of the bush 14 to which the conduit 12 is fixed to the joint body 1 as a pre-coupling step.
The nut 13 is inserted into the fitting opening 11g of No. 1 and lightly tightened. When the nut 13 is further tightened from this state, the outer packing 15 sandwiched between the inward flange 13a of the nut 13 and the outward flange 14a of the bush 14
The inner packing 17 sandwiched between the end surface of the fitting portion 14b of the bush 14 and the stepped portion 11h of the joint body 11 absorbs the axial tightening force acting between the nut 13 and the joint body 11. They are simultaneously affected and deformed together, resulting in the state shown in FIG. 1B.

That is, the outer packing 15 is in direct contact with the flange portion 14a of the bushing 14 and is also deformed in the radial direction so as to come into close contact with the inner surface of the first cylindrical portion of the washer 16 and the outer surface of the electric conduit 12. Therefore, the gaps between the electric conduit 12, the nut 13, and the bush 14 are sealed, and rainwater and the like are reliably prevented from entering from outside the joint pipe. Also, the outer packing 15 and the nut 1 are connected by the annular portion 16a of the washer 16.
Since the frictional force between the nut 13 and the inwardly directed flange portion 13a of the nut 13 is reduced, there is no risk that the rotation of the nut 13 during tightening will be directly transmitted to the outer packing 15 and cause it to twist or rotate together. Therefore, the above-mentioned excellent sealing performance is reliably guaranteed regardless of the skill of the connection work, and damage to the electric conduit 12 due to twisting is also eliminated.

On the other hand, when the inner packing 17 is in a tightened state, its front and rear end surfaces 17c and 17b are in close contact with the end surface of the bushing fitting portion 14b and the stepped portion 11h, respectively, so that a secure seal is created between the bushing 14 and the joint body 11. will be done. In this case, as described above, the bush 14 and the joint body 11 do not rotate relative to each other during tightening, so the inner packing 1
7 is not likely to be twisted and deformed, and therefore the reliability of the seal is high. In addition, while the inner packing 17 is restricted from expanding its diameter, it is free to deform inwardly, so when it is tightened, it is compressed and deformed and at the same time bends and contracts in diameter. The inner circumferential portion of the axially central portion of the inner packing 17 is crimped onto the outer circumferential surface of the cable 19 inserted through the joint body 11 to form a seal.
Therefore, rainwater or the like that has entered the electric conduit 12 is blocked and there is no possibility of it entering the outlet 11f, and it is possible to prevent short circuits inside the device due to rainwater or the like. Also, in case the cable 19
Even if the cable becomes corroded by rainwater, it is possible to replace the cable, and this is less of a problem than accidents caused by contact failures caused by rainwater intrusion. Incidentally, in this embodiment, since the inner packing 17 has a stepped cylindrical shape, the inner circumferential surface 17 is deformed with the axial center near the tapered surface 17g as the center of deformation during compressive deformation due to tightening as shown in the figure.
Since a bends and contracts so as to draw a smooth arc, and at the same time the amount of inner diameter reduction becomes large relative to the amount of compression,
The allowable range of cable outer diameter that can be sealed is expanded,
One type of inner seal is sufficient for cables with diameters of 5 mm to 8 mm, and even more reliable sealing performance can be expected.

By the way, as mentioned above, according to this pipe joint,
Excellent waterproof and dustproof performance is obtained, but due to piping design and construction reasons, the connection part installed at the hanging part of the conduit 12 from a cable duct installed at a high place outdoors, an operation box, etc. If the conduit 12 is left exposed and rainwater enters the connection, or if it is used in a humid environment, the conduit 12
If dew condensation occurs on the inner circumferential surface of the conduit 12, water in the conduit 12 flows down the hanging part and accumulates near the bush 14, which may cause rust or cable corrosion. However, in this embodiment, the bush 14
Since the drain hole 18 is provided in the drain hole 18, there is no possibility that water will accumulate and cause any inconvenience as described above.
That is, the water drain hole 18 is formed between the large diameter end surface of the joint body 11 and the bushing flange portion 14 in the tightened state.
Together with the annular gap 20 that occurs between the annular gap 20 and the back crush that occurs between the male threaded portion 11e of the joint body and the female nut threaded portion 13b, a water drainage path that communicates the internal space of the bush 14 and the conduit 12 with the outside is configured. However, it has a function of draining water accumulated near the bush 14 from a portion close to the inner packing 17 to the outside of the pipe joint via this water drain path.
In addition, in this case, since the drain holes 18 are provided at three cylindrical locations at equal intervals, even if the conduit pipes 12 are used in a horizontal position where they are connected horizontally as shown in the figure, either Since the water drain hole 18 is located below, water can be drained reliably.

〔Effect of the invention〕

As explained above, the pipe joint according to the present invention is
By tightening the nut, a seal is reliably formed between the bushing and the joint body so that the front and rear end faces of the inner packing come into close contact with the fitting end face of the bush and the stepped portion of the joint body, respectively. In other words, while the inner packing is restricted from expanding its diameter, it is free to deform inwardly, so when it is tightened, it is compressed and deformed and at the same time bends and contracts in diameter. The axial center of the inner packing is in close contact with the outer peripheral surface of the cable inserted through the bushing, creating a seal, and even if rainwater gets into the bushing, the water will not be led to the equipment side through the inner packing. In addition, the inner packing is not simply compressed and deformed, but is bent, and the diameter decreases the most at the center in the axial direction, so the amount of deformation in the radial direction can be increased, for example, the outer diameter can be reduced by 5 mm to 8 mm. One type of inner packing is sufficient for different cables, and one type of pipe joint can be used for many types of cables with different outer diameters.

Further, near the outward facing flange of the fitting part provided on the bushing, water drain holes passing through the fitting part in the radial direction are provided at multiple locations in the circumferential direction, and these drain holes are connected to the joint body and the bushing. Since the opening is made in the annular gap between the ends of the cable duct, the connection part of the hanging part of the conduit that connects the cable duct, etc. located at a high place outdoors, and the pipe fitting attached to the equipment located below. Even if rainwater enters the conduit or condenses on the inner circumferential surface of the conduit, and this water is led to the lower end of the conduit, it will pass through the gap between the conduit and the conductor such as a cable, and then enter the bushing. guided by the water drain hole;
It is quickly discharged outside the pipe fitting from a position close to the inner packing through the annular gap and does not accumulate inside the pipe fitting, thereby preventing premature aging of the cable and inner packing and corrosion of the bushing. .

And, another conduit pipe joint according to the present invention is as follows:
When the fitting part of the bushing to which the conduit is fixed is inserted into the fitting opening of the joint body and the nut is tightened, the outer packing sandwiched between the inward flange part of the nut and the outward flange part of the bushing, The inner packing sandwiched between the end face of the fitting portion of the bush and the stepped portion of the joint body simultaneously receives the axial tightening force acting between the nut and the joint body, and is compressed and deformed together.

At this time, the outer packing is in direct contact with the outward flange of the bushing and in close contact with the inward flange of the nut via the annular part of the washer, and is also deformed in the radial direction to tighten the outer surface of the conduit. and is also crimped onto the inner circumferential surface of the cylindrical portion of the joint body side of the washer. Therefore, the gaps between the conduit, nut, and bushing are sealed. In addition, the presence of the annular washer, especially its annular portion, reduces the frictional force between the end face of the outer packing and the inner flange of the nut, so that the rotation of the nut during tightening is directly transmitted to the outer packing, causing the tightening of the nut. There is no risk of twisting or co-rotation, and ease of assembly is improved. Furthermore, since the bush and the joint body do not rotate relative to each other when the nut is tightened, there is no risk of twisting and deforming the inner packing, and this has the effect of increasing the reliability of the seal provided by the packing.

[Brief explanation of drawings]

FIG. 1A is a longitudinal sectional side view of the upper half of an embodiment of the present invention showing the state before tightening, FIG. 1B is a longitudinal sectional side view of the upper half showing the state after tightening, and FIGS. The figures are longitudinal sectional side views of the upper half of the bush, washer, and inner packing of the above embodiment. FIG. 5 is a longitudinal cross-sectional side view of the upper half of the conventional example. 11...Joint body, 11g...Fitting opening portion of the coupling body, 11h...Same step section, 12...Electrical conduit, 13
...Nut, 13a...Inward flange part of nut, 14...Bushy, 14a...Outward flange part of bushing, 14b...Fitting part, 14c...
...Insertion part, 15...Outer packing, 16...Washer, 16a...Annular part, 16b, 16c...Cylindrical part, 17...Inner packing, 17a...Inner peripheral surface of inner packing, 17b, 17c ...Same both end faces, 1
7d... Same outer peripheral surface, 18... Drain hole, 19...
Cable, 20... annular gap.

Claims (1)

[Claims] 1. A substantially cylindrical joint body that is coupled to the equipment exterior, and an outward flange portion having a diameter larger than the outside diameter of the conduit to be connected to the joint body, and the flange portion An insertion portion that fits and secures to the inner diameter portion of the end of the conduit is formed on one side with the two sides in between, and a fitting portion that removably fits into the joint body is formed on the other side, and the outward flange portion of this fitting portion is formed on the other side. a substantially cylindrical bushing having a plurality of drainage holes provided in the circumferential direction that penetrate the fitting part in a radial direction; and a nut having an inward flange portion facing the end face of the outward flange portion, and a cylindrical inner packing made of an elastic body and interposed between the fitting portion of the bush and the joint body. The joint body has a fitting opening portion into which the fitting portion of the bushing is fitted, and an annular inner step portion protruding inside the fitting opening portion, and the fitting portion of the bushing is fitted into the fitting portion. The inner packing is sandwiched between the inner packing and the end face of the joint, and a nut is screwed into the outer circumferential portion, and the inner packing is fitted into the fitting opening of the joint body while restraining its diameter from expanding toward the outer peripheral side. When the nut is tightened, the outward flange of the bushing approaches the inner stepped part of the joint body, and as a result, the bushing is compressed and deformed elastically in the axial direction, flexing and contracting in diameter, so that the inner circumferential surface of the central part in the axial direction becomes the same as the electric wire. The bushing is crimped from inside the pipe to the outer peripheral surface of the cable passing through the joint body, and the water drain hole provided in the bushing is opened into an annular gap formed between the end faces of the joint body and the bushing. Pipe fittings for electrical conduits. 2. The inner packing is formed of a cylindrical inner circumferential surface, both end surfaces at the front and rear thereof that are substantially parallel to each other, and a stepped outer circumferential surface, and the outer circumferential surface has an outer circumferential surface that is substantially the same as the entrance portion of the fitting opening. A small-diameter cylindrical surface that has a diameter and is adjacent to one end surface, a large-diameter cylindrical surface that has a larger diameter and is adjacent to the other end surface, and a tapered surface that gradually reduces in diameter from the large-diameter cylindrical surface to a small-diameter cylindrical surface. 2. The electrical conduit pipe joint according to claim 1, which has an outer shape in which the end face on the large diameter cylindrical surface side is seated on the inner flange surface of the joint body. 3. It has a nearly cylindrical joint body that is connected to the equipment exterior, and an outward flange part with a larger diameter than the outside diameter of the conduit to be connected to this joint body, and a flange part on one side with this flange part in between. An insertion part that fits and secures to the inner diameter part of the end of the conduit is formed on the other side, and a fitting part that removably fits into the joint body is formed on the other side, and a fitting part is formed near the outward flange part of the fitting part. a substantially cylindrical bushing having drain holes extending radially through the bushing at multiple locations in the circumferential direction, and loosely fitting into the outward flange of the bushing from the conduit side; a nut having an inward facing flange formed opposite to its end face; a cylindrical outer packing made of an elastic body interposed between the inward facing flange of the nut and the outward facing flange of the bush; A cylindrical inner packing interposed between the fitting part of the bush and the joint body and made of an elastic body, a cylindrical part on the joint main body side that covers a portion of the outer peripheral surface of the outer packing near the nut, and an outer packing. a washer integrally formed with an annular portion sandwiched between the end surface and the inner end surface of the inward flange portion of the nut, and a cylindrical portion inserted between the inner circumferential surface of the inward flange portion of the nut and the outer circumferential surface of the electric conduit; The joint body has a fitting opening portion into which the fitting portion of the bushing is fitted, and an annular inner step portion protruding inside the fitting opening portion, and the fitting portion of the bushing is fitted into the fitting portion. The inner packing is sandwiched between the inner packing and the end face of the joint, and a nut is screwed into the outer circumferential portion, and the inner packing is fitted into the fitting opening of the joint body while restraining its diameter from expanding toward the outer peripheral side. When the nut is tightened, the outward flange of the bushing approaches the inner stepped part of the joint body, and as a result, the bushing is compressed and deformed elastically in the axial direction, flexing and contracting in diameter, so that the inner circumferential surface of the central part in the axial direction becomes the same as the electric wire. The bushing is crimped from inside the pipe to the outer peripheral surface of the cable passing through the joint body, and the water drain hole provided in the bushing is opened into an annular gap formed between the end faces of the joint body and the bushing. Pipe fittings for electrical conduits.