JP2000146063A - Fuel tube combining structure of automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure fluid adhesion properties in a mutual relation between the outer circumferential surface of a nipple, and the inner circumferential surface of a tube, and prevent the tube from falling down carelessly. SOLUTION: This combining structure comprises a tube 2 pressed in a nipple 1 with pressure, which has the plural number of peripheral projections 10a at the outer circumferential part, and its pull-out strength and sealing performance are so designed as to be secured by letting the peripheral projections 10a bite in the inner wall of the tube 2. The inner wall surface of a short pipe 3 made out of material, is in a pressure contacting condition, which is almost neither swelled nor lowered in stiffness even if it is outwardly inserted in the tube 2, and furthermore, is brought into contact with fuel high in temperature, in the outer circumferential surface area of the tube 2, which is swelled up because the peripheral projections 10a bite in the inner wall of the tube 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel tube connecting structure for an automobile.

[0002]

2. Description of the Related Art For example, FIG.
As shown in FIG. 1, there is a structure in which a tube 2 is press-fitted into a nipple 1 screwed to a fixed wall or a device and joined. In this embodiment, a plurality of peripheral projections 10a are formed on the outer peripheral surface of the nipple 1, and the presence of the peripheral projections 10a prevents the tube 2 from coming off from the nipple 1, and the nipple 1
The fluid tightness between the outer peripheral surface of the tube and the inner peripheral surface of the tube 2 is ensured.

However, when the above tube connecting structure is used for a fuel system of an automobile, the tube 2 swells,
Fluid tightness between the outer peripheral surface of the nipple 1 and the inner peripheral surface of the tube 2 cannot be secured, or the tube 2 may come off from the nipple 1. In particular,
In the use where the tube joint is immersed in the fuel, the above-mentioned situation is remarkable.

[0004] Therefore, in the automobile industry, it is possible to secure fluid tightness between the outer peripheral surface of the nipple and the inner peripheral surface of the tube, and to connect the fuel tube of the vehicle without inadvertent removal of the tube from the nipple. Development of the structure is desired.

[0005]

Therefore, according to the present invention, fluid tightness between the outer peripheral surface of the nipple and the inner peripheral surface of the tube can be ensured, and a situation in which the tube accidentally comes off from the nipple occurs. An object of the present invention is to provide a fuel tube coupling structure for an automobile.

[0006]

Means for Solving the Problems (Invention of Claim 1)
The fuel tube connecting structure for an automobile according to the present invention is formed by press-fitting a tube into a nipple having a plurality of peripheral projections on an outer peripheral portion, and the peripheral projections bite into the inner wall of the tube so that pull-out strength and sealing performance are ensured. A tube connecting structure, in which the swelling hardly occurs even when the outer peripheral surface portion of the tube raised by the biting of the peripheral protrusion into the inner wall of the tube is in contact with a fuel which is extrapolated to the tube and has a high temperature, and has a low rigidity. The inner wall surface of the short tube made of a material that does not decrease is in a pressure contact state. (Invention of Claim 2) The fuel tube connecting structure for an automobile according to the present invention is the same as that of Claim 1 except that
A cylindrical body made of a material having excellent heat resistance and fuel oil resistance. (Invention of Claim 3) The fuel tube connecting structure for an automobile according to the present invention is the same as that of Claim 1 except that
Section C made of a material with excellent heat resistance and fuel oil resistance
It is an open cylinder of a mold. (Invention of Claim 4) In the fuel tube connecting structure for an automobile according to the present invention, the short pipe is made of synthetic resin or metal in relation to the invention of Claim 2 or 3. (Invention of Claim 5) The fuel tube connecting structure for an automobile according to the present invention is the same as that of Claim 1 except that
Two metal ring bands are externally fitted and fixed to the resin cylindrical body, and the arrangement positions of the metal ring bands correspond to the positions of the circumferential projections at both ends of the nipple. (The invention according to claim 6) The fuel tube connecting structure for an automobile according to the present invention relates to the invention according to any one of claims 1 to 5, wherein the rotation of the short pipe with respect to the nipple is prevented by preventing rotation of the tube and the nipple. In order to prevent rotation
The short pipe has a detent piece.

[0007] The function of the fuel tube connecting structure of the vehicle according to the present invention will be clarified in the following embodiments of the present invention.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. [Embodiment 1] FIG. 1 shows a fuel tube connecting structure for an automobile of this embodiment. (About the whole structure of the fuel tube connecting structure) As shown in FIG. 1, the fuel tube connecting structure is formed by press-fitting the tube 2 into a nipple 1 having three peripheral protrusions 10a on the outer peripheral portion. The pull-out strength and the sealing property are secured by biting into the inner wall of the tube 2, and the outer peripheral surface portion of the tube 2 that is raised by the biting of the circumferential projection 10 a into the inner wall of the tube 2 is attached to the tube 2. The inner wall surface of the short tube 3 made of a material that hardly swells even when it is inserted and comes into contact with a high-temperature fuel and does not decrease in rigidity is brought into a pressed state. (Configuration of each member for forming fuel tube connection structure
1 ) As shown in FIGS. 1 and 2, the nipple 1 includes a tube connecting portion 10 having the circumferential protrusion 10a formed on one end and a male screw portion 12 formed on the other end. As shown in FIG. 1, the circumferential projection 10a has an inclined surface on the front side in the tube insertion direction and a vertical surface on the back side in the tube insertion direction, as shown in FIG. It is formed in a certain triangular cross section. Note that the nipple 1 is made of PBT (polybutylene terephthalate resin) containing a reinforcing material,
The outer diameter of 10a is set to 8.90 mm.

The tube 2 is made of a PBN elastomer (polybutylene naphthalate-based elastomer) and has an outer diameter of 8.15 mm and an inner diameter of 6.15 mm.

The short tube 3 is made of PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer resin), and has an outer diameter of 12 mm and an inner diameter of 10 mm. The length of the short tube 3 is, as shown in FIG.
a is set so that it can be surrounded. (About the connection method of the fuel tube) As shown in FIG. 2, the connection of the nipple 1 and the tube 2 is carried out by inserting the short tube 3 into the end of the tube 2 gripped by the chuck T, and in this state, the tube 2 At the end of the nipple 1 tube connection
This is done by pressing 10 in.

The nipple 1 is press-fitted into the end of the tube 2 in a state where the short pipe 3 is not inserted into the end of the tube 2, and then the short pipe 3 is press-fitted into the end of the tube 2. You may. (About the function of this fuel tube connection structure) In this connection state, as described above, the outer peripheral surface of the tube 2 raised by the biting of the circumferential projection 10a into the inner wall of the tube 2 The inner wall surface of the short pipe 3 made of PFA hardly swells even when it comes into contact and the rigidity is not reduced. For example, the joint between the nipple 1 and the tube 2 is made of sour gasoline or alcohol-mixed fuel. Even when immersed in a highly corrosive fuel, the tube 2 swells, but the short tube 3 hardly swells, as shown in FIG. Thus, the tube 2 is pressed into contact with the tube insertion portion and the short tube 3, so that the pull-out strength and the sealing property are secured. This effect becomes more remarkable as the number of the peripheral protrusions 10a between the positions AA increases.

The fuel tube connecting structure shown in FIGS. 8 and 1 using the nipple 1, the tube 2, and the short tube 3 is heat-aged (170 ° C. × 2 hours) and immersed in a fuel such as sour gasoline (65). ° C x 500 hours)
When a test for confirming pull-out strength and sealability was actually performed, it was found that the joint structure of FIG. 1 can maintain pull-out strength and sealability. [Other Embodiments of Short Tube 3] A. The following modes can be adopted provided that the material is excellent in heat resistance and fuel oil resistance, and hardly swells due to contact with fuel oil and hardly decreases in rigidity. A short tube 3 made of metal can be employed. As shown in FIGS. 4 and 5, a short cylinder 3 made of a synthetic resin or metal and having a C-shaped cross section and having a narrow slit 30 formed therein can be employed. B. Next, as shown in FIG. 6, two synthetic resin or metal ring bands 32 (a synthetic resin ring band 32)
In this case, the short pipe 3 may be formed integrally with the resin cylindrical body 31). In this case, the arrangement position of the synthetic resin or metal ring band 32 is
Although it is necessary to correspond to the position of 10a, the same function can be exerted even if the rigidity of the resin cylindrical body 31 is somewhat reduced. C. Subsequently, in order to prevent the rotation of the short pipe 3 with respect to the nipple 1, a short pipe 3 provided with a detent piece 33 can be employed as shown in FIG. The rotation of the short tube 3 is prevented by rotating the rotation preventing piece 33 with the flat portions 11a, 11a of the tool corresponding portion 11.
a (see FIG. 2). [Others] The nipple 1 of the above embodiment has the male screw portion 12 connected to another member, but the nipple 1 is not limited to this form.

[0013]

Since the present invention has the above-described configuration, it has the following effects.

From the contents described in the embodiments of the invention, fluid tightness between the outer peripheral surface of the nipple and the inner peripheral surface of the tube can be ensured, and a situation in which the tube is accidentally pulled out of the nipple may occur. A fuel tube connection structure for an automobile that does not cause the problem can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a fuel tube coupling structure of an automobile according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a method of connecting the fuel tubes.

FIG. 3 is a sectional view for explaining the function of the fuel tube coupling structure.

FIG. 4 is a perspective view of a short pipe of another embodiment used for the fuel tube coupling structure.

FIG. 5 is a perspective view of a short pipe of another embodiment used for the fuel tube coupling structure.

FIG. 6 is a perspective view of a short pipe of another embodiment used for the fuel tube coupling structure.

FIG. 7 is a perspective view of a short pipe of another embodiment used for the fuel tube coupling structure.

FIG. 8 is a sectional view of a conventional tube coupling structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Nipple 2 Tube 3 Short pipe 10 Connection part 10a Peripheral projection 11 Tool corresponding part 11a Flat part 12 Male thread part 30 Slit 31 Resin cylindrical body 32 Metal ring band 33 Detent piece

Claims (6)

[Claims] 1. A tube coupling structure comprising a tube press-fitted into a nipple having a plurality of peripheral projections on an outer peripheral portion, wherein a pull-out strength and a sealing property are secured by biting the peripheral projections into the inner wall of the tube. A short pipe made of a material that is hardly swelled even when it comes into contact with a high-temperature fuel and is hardly reduced in rigidity when the outer peripheral surface of the tube is raised due to the protrusion of the peripheral protrusion into the inner wall of the tube. A fuel tube coupling structure for an automobile, wherein an inner wall surface of the vehicle is in a pressure contact state. 2. The fuel tube coupling structure for an automobile according to claim 1, wherein the short pipe is a cylindrical body made of a material having excellent heat resistance and fuel oil resistance. 3. The fuel tube coupling structure for an automobile according to claim 1, wherein the short pipe is a C-shaped cross-section cylindrical body made of a material having excellent heat resistance and fuel oil resistance. 4. The structure according to claim 2, wherein the short pipe is made of synthetic resin or metal. 5. A short pipe, wherein two metal ring bands are externally fitted and fixed to a resin cylindrical body, and the disposition position of the metal ring band is determined by the positions of circumferential projections at both ends of the nipple. The fuel tube coupling structure for an automobile according to claim 1, wherein the structure is adapted to: 6. The short pipe is provided with a detent piece for preventing rotation of the tube and the nipple by preventing rotation of the short pipe with respect to the nipple. A fuel tube coupling structure for an automobile according to any one of the above.