JPH0611084A - Tube joint for double tube - Google Patents

Abstract

PURPOSE:To improve strength and safety by installing packings on a base part and end face of a male screw of a joint main body for screwing and tightening a box nut on the fitting main body, reducing a diameter of a sleeve by means of a tapered port of the box nut for holding an outer tube, and simultaneously reducing a diameter of a biting projection part of the sleeve for holding an inner tube. CONSTITUTION:A tube joint is composed of a joint main body 1, a box nut 2, a sleeve 3, and O rings 4a to 4d. The sleeve 3 has a waved inner peripheral surface 3a which is engaged with a wavy outer peripheral surface of an outer tube 6 while crossing the O ring 4a, and a biting projection part 3b whose diameter is smaller than an outer diameter of an inner tube 5 on its front end. The O rings 4c and 4d are respectively installed on a base part and end face of a male screw part 1a of the fitting main body, for screwing and fastening the fitting main body 1 to the box nut 2. When the fitting main body and the box nut are fastened, the diameter of the sleeve 3 is reduced by a tapered port 2b of the box nut for holding the outer tube 6. At the same time, the diameter of the biting projection part 3 is reduced for holding the inner tube 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is particularly used for a pipe system for delivering liquefied petroleum gas in a liquid state, and a pipe used for a double pipe in which an inner pipe is a straight pipe and an outer pipe is a bellows pipe. It concerns a joint.

[0002]

2. Description of the Related Art In recent years, in the field of household propane gas and the like, a method of making flexible piping using a metal bellows tube has become widespread. For example, several bellows pipes are drawn from a header connected to a pipe on the supply side and then piped to each room. As an example of a pipe joint used for this piping, Japanese Patent Publication No. 3-3837
There is one shown in FIG. 3 disclosed in Japanese Patent Publication. Explaining this pipe joint here, the joint body 10 has a pipe screw 10a at one end of the outer periphery thereof, a through hole 10b inside thereof, a parallel male screw 10c at the other end thereof, and an inner periphery thereof. It has a taper hole portion 10d that is reduced in diameter toward the back. A sleeve 12 having a cap nut 11 that is screwed into the external thread 10c of the joint body 10 and a corrugated inner peripheral surface that engages with the corrugated outer peripheral surface of the bellows tube 15 and is notched in the axial direction is formed. As shown in FIG. 3, the end portion of the bellows tube 15 is protruded by about 2 to 3 peaks to break the notch of the sleeve 12, and this is wrapped around the outer peripheral surface of the bellows tube 15, and this sleeve is When 12 is fitted into the tapered hole portion 10d of the joint body 10 and the cap nut 11 is tightened, the cap nut 11 and the bellows pipe 15
The sleeve 12 does not rotate together with the tapered hole portion 1
The outer surface of the bellows tube 15 is tightened by reducing the diameter while moving to the back of 0d. Then, the peak of the pipe end is crimped and connected to the gasket 13 provided on the wall portion of the joint body 10.

On the other hand, recently, there is a movement to use butane gas as fuel gas for home use instead of propane gas. The main sources of liquefied petroleum gas are propane and butane, respectively.
It accounts for nearly 0% and is produced at the same ratio. Both produce approximately the same amount of fuel calories, but in terms of supply and demand, butane has the advantage of being extremely cheap, about 1/7 that of propane. However, since propane has a boiling point of -42.0 ° C, which is significantly lower than -0.5 ° C of butane, it does not liquefy at atmospheric pressure even in winter, so it can always be gasified and supplied as household fuel. . However, despite the low cost of butane as described above, butane does not vaporize in the winter when the temperature decreases because its boiling point is as high as −0.5 ° C. That is, there is a problem that butane gas is not generated from the container. Therefore, butane, which is below -0.5 ° C in winter in most regions, cannot be used as domestic fuel in Japan,
In reality, it is only used as a fuel for taxis as industrial gas by the forced vaporization method or as auto gas by mixing propane.

From the above, when it is attempted to use butane as a household fuel from now on, a pipe system is used in which it is transported in a liquefied state up to the front of the end combustion equipment and vaporized by a vaporizer in front of the equipment. It is safe to adopt. However, the liquefied gas has not been conventionally conveyed by using the above-described conventional bellows pipes or pipes for joints, and pipes and pipe joints therefor are not available in the current market.

[0005]

By the way, in order to convey butane in a liquefied state, it is necessary to liquefy it by cooling or pressurizing it. However, cooling is considered to be difficult because of problems with equipment and the like. Therefore, the pressurization method is considered to be the usual method, but the vapor pressure for maintaining the liquefaction is ² Kgf / cm ² at 20 ° C and 4 Kgf at 40 ° C.
/ Cm ² or more, and if the maximum use condition is set to 60 ° C., a pressurized state of 6 Kgf / cm ² or more will be obtained, and the above-mentioned prior art pipe joint remains unsatisfactory in strength. In the unlikely event that butane leaks out of the piping system, the volume expansion due to vaporization is extremely large (about 230 times), and the gas is instantly spread over a wide range, which is a very dangerous state. Therefore, safe and highly reliable piping and fittings are required. An object of the present invention is to provide a reliable pipe joint in terms of strength and safety by using butane as a household fuel to balance the supply and demand of propane and butane and being used for butane liquid supply piping. And

[0006]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above object, that is, a double tube having an inner tube which is a straight tube and an outer tube which is a corrugated tube having a corrugated shape. A pipe joint for connection, having a threaded portion on the outer periphery of one end, and an inner periphery having an inner diameter substantially equal to the outer diameter of the inner pipe and forming a pipe receiving wall portion for receiving the inner pipe in the inner portion. And a female threaded portion that is screwed into the male threaded portion of the jointed body are formed at one end on the inner circumference, and a taper hole portion is formed on the inner circumferential surface that continues at a small angle toward the back. A cap nut and a corrugated inner peripheral surface that engages the packing on the corrugated outer peripheral surface of the outer tube, and a front projection that has a biting protrusion that can be smaller in diameter than the outer diameter of the inner tube. Notch having a tapered shape or a tapered outer peripheral surface having an angle smaller than the taper angle of the tapered hole portion, and capable of being divided in the circumferential direction Between the sleeve provided in the axial direction, between the male thread portion of the joint body and the female thread portion of the cap nut, and between the end surface of the male thread portion of the joint body and the end surface of the biting protrusion of the sleeve. And a packing that is respectively mounted between the sleeve nut and the outer tube, and the sleeve and the outer tube are fitted into the tapered hole by screwing the cap nut, and the biting protrusion is bited into the inner tube. It is a pipe joint for double pipes.

[0007]

[Function] The tip of the outer tube is cut off so that the tip of the inner tube projects more than the tip of the outer tube, the cap nut is inserted through the outer tube, the packing is attached to the outer circumference of the outer tube, and the notch of the sleeve is opened. Attach a sleeve so that it straddles the packing attached to the outer circumference of the pipe, and that the biting protrusion protrudes beyond the tip of the outer pipe,
When packing is attached to the base and end face of the male thread of the joint body and the joint body and cap nut are screwed together and tightened, the sleeve reduces the diameter by the tapered hole of the cap nut and grips the outer pipe. The biting protrusion of the sleeve is also reduced in diameter to grip the inner pipe, and each packing keeps the gas in the double pipe airtight.

[0008]

The present invention will be described with reference to the drawings. FIG. 1 shows an embodiment of the present invention, and this pipe joint comprises a joint body 1, a cap nut 2, a sleeve 3, and O-rings 4a to 4d. On the other hand, the double pipe to be connected using this pipe joint includes an inner pipe 5, an outer pipe 6 having a bellows shape in the axial direction, and a protective pipe 7 for protecting the outer surface of the outer pipe 6.
Consists of. First, the joint body 1 has one end (the left end in the drawing).
The male screw portion 1a is provided, and the inner circumference 1b of the portion where the male screw portion 1a is provided has an inner diameter substantially equal to the outer diameter of the inner pipe 5, and the inner pipe 1 has a distal end in the inner portion 1b. Tube receiving wall 1 for receiving
c is formed, and a circular truncated cone surface 1d is formed on the inlet side of the inner circumference 1b, the diameter of which is increased toward the inlet side. Cap nut 2
Has a female thread portion 2a that is screwed into the male thread portion 1a of the joint body at one end side (right end side in the drawing), and has a taper hole portion on the inner peripheral surface that continuously reduces in diameter at a small angle toward the back. 2b is formed. The sleeve 3 has an O-ring 4 on the corrugated outer peripheral surface of the outer tube 6.
It has a corrugated inner peripheral surface 3a that engages over a, and the front end portion has a biting protrusion 3b that can have a smaller diameter than the outer diameter of the inner pipe 5.
Is formed so that it can be divided in the circumferential direction by a notch 3c in the axial direction as shown in FIG. Further, the outer peripheral surface of the sleeve 3 of the present embodiment is formed in a cylindrical shape, but it may be a tapered outer peripheral surface having an angle smaller than the taper angle of the tapered hole portion 2b of the cap nut. The O-ring 4a is mounted inside the sleeve 3 as described above, the O-ring 4b is mounted between the inner surface of the collar 2c of the cap nut and the outer surface of the outer pipe 6, and the O-ring 4c is the external thread 1a of the joint body. And the female thread 2a of the cap nut, and the O-ring 4d is mounted between the end surface of the male thread 1a of the joint body and the end surface of the biting protrusion 3b of the sleeve.

The present embodiment is configured as described above,
The tip of the protective tube 7 and the tip of the outer tube 6 are cut off so that the tip of the inner tube 5 projects about 12 to 15 cm from the tip of the outer tube 6, and the tip of the outer tube 6 is more than the tip of the protective tube 7. To project. Next, insert the cap nut 2 into the outer tube 6 and O
Notch 3c of sleeve 3 with rings 4a and 4b attached
The sleeve 3 such that the sleeve 3 is opened so as to straddle the O-ring 4a, and the protruding portion 3b projects beyond the tip of the outer tube 6.
Then, the O-rings 4c and 4d are attached to the base and the end face of the male thread 1a of the joint body, respectively, and the joint body 1 and the cap nut 2 are screwed and tightened. When the joint body and the cap nut are tightened, the sleeve 3 reduces the diameter by the tapered hole portion 2b of the cap nut to grip the outer pipe 6, and at the same time, the biting protrusion 3
b is also reduced in diameter to grip the inner tube 5. The latter, that is, the diameter-reducing action of the biting protrusion 3b, is caused by the truncated cone surface 1 formed on the joint body.
more reliably by means of d, and thus the inner pipe 5, the outer pipe 6
Both exhibit pullout prevention power. On the other hand, the O-ring 4a seals between the sleeve 3 and the outer pipe 6, the O-ring 4b seals between the cap nut 2 and the outer pipe 6, and the O-ring 4c seals between the joint body 1 and the cap nut 2. And the O-ring 4d seals between the joint body 1 and the sleeve 3, thus keeping the gas in the inner pipe 5 airtight and at the same time preventing the external fluid from entering the outer pipe 6.

After assembling the double pipe and the pipe joint,
The air pressure of 1.1 kgf / cm ² and 5 Kgf / cm ² to act for 5 minutes into the inner tube 5 was tested for leaks in water,
I confirmed that there were no leaks. 26 in the inner pipe 5
Water pressure of Kgf / cm ² was applied for 2 minutes to test for leakage, and it was confirmed that there was no leakage. Therefore, the pipe joint for this double pipe is a reliable pipe joint in terms of strength and safety.

[0011]

Industrial Applicability According to the present invention, a pipe joint for a double pipe which is mainly used in a butane liquid feed pipe and is reliable in strength and safety is provided.

[Brief description of drawings]

FIG. 1 is a front view of a lower half of an upper half section of an embodiment of the present invention.

FIG. 2 is a right side view of the sleeve of the embodiment.

FIG. 3 is a front view of a lower half of an upper half section of a conventional example.

[Explanation of Codes] 1 ... Fitting body 1a ... Male thread 1
b ... inner circumference 1c ... pipe receiving wall 1d ... truncated cone surface 2
... Cap nut 2a ... Female thread 2b ... Taper hole 2
c ... Tsuba 3 ... Sleeve 3a ... Corrugated inner peripheral surface 3
b ... bite protrusion 3c ... notch 4a-4d ... O-ring 5
… Inner tube 6… Outer tube 7… Protective tube

Claims (1)

[Claims] 1. A pipe joint for connecting a double pipe, wherein the inner pipe is a straight pipe and the outer pipe is a corrugated pipe formed in a corrugated form, and having a threaded portion on the outer periphery of one end, The inner circumference has an inner diameter approximately equal to the outer diameter of the inner pipe, and a joint main body having a pipe receiving wall portion for receiving the inner pipe in the inner portion, and a female screw portion screwed to the male screw portion of the joint main body at one inner periphery. And a cap nut having a taper hole portion formed on the inner peripheral surface that is uniformly reduced in diameter at a small angle toward the back, and a corrugated inner periphery that engages the packing on the corrugated outer peripheral surface of the outer pipe. Has a surface, has a biting protrusion that can be smaller in diameter than the outer diameter of the inner pipe, and has a cylindrical or tapered outer peripheral surface with an angle smaller than the taper angle of the tapered hole. A sleeve provided with a notch that can be divided in the circumferential direction in the axial direction, a male thread of the joint body and a female thread of the cap nut And a packing attached respectively between the end surface of the external thread portion of the joint body and the end surface of the biting protrusion of the sleeve, and the sleeve and the outer pipe by screwing the cap nut. A pipe joint for a double pipe, wherein and are fitted into the tapered hole portion, and the biting protrusion is made to bite into the inner pipe.