JPH07293389A - High-pressure fuel injection pipe - Google Patents

Abstract

PURPOSE:To reduce a manufacturing manhour as an outer pipe having a connecting head of conical crown formed as surface for pressing a mating seat at a connecting end, enhance productivity and improve the fitness of the outer pipe to an inner pipe by forming the outer pipe out of aluminum material and the inner pipe out of material having high strength and corrosion resistance. CONSTITUTION:An outer pipe l of aluminum material with relatively thick wall thickness and small diameter is extrusion molded from a billet and a thin-wall inner pipe 3 of high strength and corrosion resistance material such as stainless steel, inconel and titanium is internally coupled tightly to the flow hole 2 of the outer pipe 1 over the whole length thereof via a doubled alignment process. Also, a connecting head 1 of conical crown formed via a buckling process is provided on the connection end of the outer pipe 1, so as to use the external surface 1'' thereof for pressing a mating seat. According to this construction, the outer pipe 1 can be immediately formed to have the prescribed small diameter, and the manhour of a work can be remarkably reduced. Also, the fitness of the outer pipe 1 to the inner pipe 3 can be enhanced and a concern about the occurrence of a gap at the superposed peripheral surface can be eliminated, thereby providing an injection pipe well coping with an internal pressure fluctuation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high pressure fuel pipe for diesel injection (hereinafter referred to as "high pressure fuel injection") used in a pipe between a pump and a nozzle holder in a diesel internal combustion engine, a high pressure fuel pipe in which a pressure accumulating portion is interposed in the pipe, and the like. It is referred to as a "tube") and has a relatively thick and thin diameter of about 20 m / m or less.

[0002]

2. Description of the Related Art Conventionally, as this type of injection pipe, cavitation and erosion on the inner peripheral surface of a small-diameter outer pipe made of steel tubing are generated on the inner peripheral surface due to the recent increase in injection pressure of fuel. Alternatively, in connection with the prevention of corrosion (hereinafter simply referred to as erosion), an inner tube made of stainless steel is internally embedded and polymerized over its entire length, and a polymerization head is formed at both ends to connect to the mating seat. An injection pipe has been developed and tested.

[0003]

However, in such a conventional technique, the purpose of preventing erosion on the inner peripheral surface is achieved by the inner pipe provided inside the outer pipe made of steel pipe material. Although it can be obtained, since the outer pipe is formed by pressure piping carbon steel, it does not require a lot of man-hours due to the repeated pipe expanding process to reduce the diameter to a specified diameter, and at the same time, the subsequent products. As a result, a great amount of labor was required due to the rigidity of the steel pipe material during the manual bending process, and the productivity was inevitably reduced, and a large force was required to form the connection head because of the steel pipe material. In addition to increasing the weight of the product, it is not necessary to use an excessive screwing tightening force at the time of connection due to the deterioration of the adhesion at the mating seat part due to the steel surface on the pressing surface. There was a tendency that the tightness with the pipe was lacking, and a gap was generally generated in the superposed peripheral surface pipe, which caused a breakage in combination with repeated internal pressure fluctuations. Also,
Due to the low natural frequency and amplitude of the steel pipe material itself, and the tendency of deterioration of vibration resistance due to fatigue near the head of the head due to bending of the connecting head, the connection state However, problems such as cracks and breakage often occur near the neck.

The present invention has been made in view of the above problems of the prior art, and the outer tube is manufactured by extruding from a billet so as to immediately obtain a small diameter having a specified dimension, thereby extremely reducing the number of working steps. At the same time, the productivity of the product is significantly improved by the easy manual bending process after that, and the product weight is reduced, and the adhesion on the pressing surface is good, and a slight tightening force is sufficient at the time of connection. None, and increased compatibility with the inner tube inside, eliminating the fear of creating a gap on the superposed peripheral surface and being able to cope with internal pressure fluctuations sufficiently. By improving the vibration resistance by reducing the fatigue caused by the buckling process near the neck of the connecting head, cracks and breakage near the neck can be prevented, and further, it is attached to the outer peripheral surface of the outer pipe. Skin tube More simultaneously dent in the outer peripheral surface, with eliminating the anxiety produced of such scratches, it is an object to provide a high-pressure fuel injection pipe which can improve the corrosion resistance.

[0005]

In order to achieve the above-mentioned object, the present invention has a connecting head having a truncated cone shape, an arc shape or an abacus bead shape, which serves as a pressing surface against a mating seat portion. In the injection pipe formed by tightly fitting a thin inner tube over the entire length on the hole circumferential surface of the small diameter outer tube,
The outer tube is made of an aluminum material having a relatively thick wall, and the inner tube is made of stainless steel, inconel, hastelloy, titanium, a titanium-based alloy or a nickel-based alloy having a high strength and a corrosion-resistant material. On the peripheral surface of the flow hole formed by the small-diameter outer pipe that has a frustoconical, arcuate, or abacus bead-shaped connecting head that forms a pressing surface against the mating seat at the fuel injection pipe and the connecting end. An injection pipe formed by tightly fitting a thin inner pipe over the entire length thereof, wherein the outer pipe is formed of an aluminum material having a relatively large thickness, and the inner pipe is made of stainless steel, Inconel, The outer tube is made of a material having high strength and high corrosion resistance, such as Hastelloy, titanium, or nickel-based alloy, and the outer surface of the outer tube is covered with stainless steel or a steel material having a plated film on the surface. All of the high-pressure fuel injection pipe configured in the above is the gist, and further, the pressing surface portion formed by the connection head is covered with a cap-shaped collar made of a metal material having a communication hole at the top surface, The abutment engagement portion formed by the hole circumference of the communication hole of the collar and the tip circumference of the inner tube is formed by welding together, or the outer tube is further extended to the back surface of the connection head. Alternatively, the connection head may be formed so as to be slightly closer to the position under the neck than the connection head.

[0006]

Since the present invention is constructed in this manner, the aluminum material as the outer pipe can extremely reduce the man-hours required for manufacturing the outer pipe, and at the same time, the subsequent molding of the connection head and the hand as a product. The productivity can be improved remarkably by the easy bending process, and the weight of the product can be reduced and the adhesion on the pressing surface can be made good, and a relatively small tightening force at the time of connection is sufficient. Even if bending is performed by increasing the compatibility with the inner tube inside, it is possible to sufficiently deal with internal pressure fluctuations without worrying about the gap between the superposed peripheral surfaces, and the outer tube itself made of aluminum material. By reducing the natural frequency of the connection head and the fatigue due to the bending process near the neck of the connection head, it is possible to improve the vibration resistance and prevent cracks and breakage near the neck. Outside adhered to the outer peripheral surface Dent in the outer peripheral surface at the same time by a pipe,
It is possible to eliminate the anxiety of scratches and improve corrosion resistance, and by attaching a cap-shaped collar to the pressing surface, the tightening force is slightly increased, but the pressing surface is eroded and corroded from fuel. It will be possible.

[0007]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a vertical cross-sectional view of a part of a high pressure fuel injection pipe of the present invention near a connecting end, and FIG. 1 equivalent to FIG. 1 according to the embodiment of the present invention, FIG. 3 is a partially cutaway sectional view of the connecting head of the embodiment of the present invention enlarged, and FIG. 4 is an enlarged view of the connecting head under the neck of another embodiment. Partial cutaway cross-section,
FIG. 6 is a view corresponding to FIG. 4 of still another embodiment, and (1) shows JIS H 40 with a pipe diameter of about 20 m / m or less.
A relatively thick and thin outer tube made of an aluminum material specified by 80 etc., extruded from a billet, and subjected to one-time pipe drawing if desired, and further if necessary. The outer peripheral surface of the outer tube (1) can be subjected to plating treatment, painting treatment or chemical conversion treatment. In addition, a stainless steel having a wall thickness of about 0.5 m / m to 1.2 m / m on the entire circumference of the hole formed by the flow holes (2) of about 4 m / m or less inside the outer pipe (1), A thin inner tube (3) made of Inconel, Hastelloy, titanium, a titanium-based alloy, a nickel-based alloy or the like and having a high strength and a high corrosion resistance is formed by fitting and fitting in a tight fit. Then, the outer circumference of the connecting end portion is a frusto-conical shape (FIG. 1), an arc shape (FIG. 5) or an abacus shape (FIG. 5) formed by buckling that forms a pressing surface (1 ") against a mating seat (not shown). 6) has a connecting head (1), and (4) is an outer tube (FIG. 2) attached to the outer peripheral surface of the outer tube (1) as another embodiment. , Stainless steel or steel material having a plated film of zinc or the like on the surface thereof, wherein the end portion of the outer tube is connected to the connecting head.
Recessed groove (1a) on the back of (1 ') (Fig. 2) or on the back
(Fig. 5), or it is formed by keeping it slightly in front of the area under the neck of the connecting head (Fig. 4, Fig. 6). And the outer tube is attached to the outer tube.
It eliminates the fear of dents, scratches, etc. on the outer peripheral surface of (1) and at the same time improves the corrosion resistance of the outer peripheral surface, and further strengthens or disperses fatigue near the head and neck. .
(5) is a further embodiment, wherein the inner tube (3) is internally provided and / or the outer tube (4) is attached, and the pressing surface (1 ') formed by the connecting head (1') is selected as desired. It is a cap-shaped collar (Fig. 3) made of a metal material attached to the 1 ") part. tube
When the tip end circumference (3 ') of (3) is in abutting engagement with the corresponding abutting engaging portion, if necessary, as shown in FIG.
As in (b), they are welded (6) to each other over the entire circumference. And not only the hole peripheral surface of the flow hole (2) but also the pressing surface
Prevents erosion at (1 ") and also prevents chemical erosion even when alcohol fuel (methanol type) or water emulsion fuel is used, and at the same time, the hole circumference and the tip circumference of the inner pipe (3).
It is designed to eliminate the fear of internal permeation of fuel from the mating surface with (3 ') and prevent chemical corrosion inside the head tip.

Reference numeral (7) is a sleeve washer fitted to the lower part of the neck of the connection head (1 '), and reference numeral (8) is a screw tightening nut for connection.

[0009]

As described above, in the high-pressure fuel injection pipe according to the present invention, the inner pipe (3), in which the outer pipe (1) is made of a thick aluminum material and is installed on the peripheral surface of the hole, or The outer tube (1) containing the inner tube is composed of the outer tube (4) adhered to the outer peripheral surface of the outer tube (1), so that the outer tube (1) is immediately manufactured to a specified size by extruding an aluminum material from a billet. Since it can be formed into a small diameter, the work man-hours can be extremely reduced, and at the same time, the subsequent forming of the connection head and hand bending as a product can be easily performed with a small force, which significantly improves the productivity. In addition, the weight of the product is light and the adhesion on the pressing surface (1 ") is good, and a slight tightening force at the time of connection is sufficient, and with the inner pipe (3). Improves habitability and eliminates the fear of gaps on the superposed peripheral surface It is possible to deal with pressure fluctuations sufficiently, and further improve the vibration resistance by increasing the natural frequency of the aluminum material itself, decreasing the amplitude, and reducing fatigue near the neck of the connecting head (1 '). It is possible to prevent cracks and breakage near the bottom, and at the same time, the outer tube (4) eliminates the fear of dents, scratches, etc. on the outer surface of the outer tube (1) at the same time. The cap-shaped collar that can improve the corrosiveness and is further applied as desired.
Due to (5), even when alcohol fuel or water emulsion fuel is used, it is possible to effectively prevent erosion or chemical erosion on the pressing surface (1 ") as well as on the peripheral surface of the flow hole (2). It is a very useful high-pressure fuel injection pipe that can be connected stably and reliably for long-term service.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a portion of a high pressure fuel injection pipe according to an embodiment of the present invention with a cutout near a connection end.

FIG. 2 is a view corresponding to FIG. 1 of the above, according to another embodiment.

FIG. 3 is a partially cutaway cross-sectional view of a connection head according to an embodiment of the present invention, which is enlarged.

FIG. 4 is a partially cutaway cross-sectional view of a connection head under neck portion of another embodiment, which is enlarged and enlarged.

FIG. 5 is a view corresponding to FIG. 4 of still another embodiment.

FIG. 6 is a view corresponding to FIG. 4 of still another embodiment.

[Explanation of symbols]

 1 Outer tube 1'Connecting head 1 "Pressing surface 2 Flow hole 3 Inner tube 3'Tip circumference 4 Outer skin tube 5 Cap collar 5'Communication hole 6 Welding

Claims (4)

[Claims] 1. A hole peripheral surface of a flow hole formed by a small-diameter outer tube having a frustoconical, arcuate or abacus bead-shaped connecting head at a connecting end which is a pressing surface against a mating seat. In the injection pipe formed by tightly fitting a thin inner pipe over its entire length, the outer pipe (1) is made of a relatively thick aluminum material, and the inner pipe (1) is 3) for stainless steel,
A high-pressure fuel injection pipe, which is made of Inconel, Hastelloy, titanium, a titanium-based alloy or a nickel-based alloy having a high strength and a high corrosion resistance. 2. A hole peripheral surface of a through hole formed by a small-diameter outer tube having a frusto-conical, arcuate or abacus bead-shaped connecting head at a connecting end which serves as a pressing surface against a mating seat. In the injection pipe formed by tightly fitting a thin inner pipe over its entire length, the outer pipe (1) is made of a relatively thick aluminum material, and the inner pipe (1) is 3) for stainless steel,
An outer tube (4) made of Inconel, Hastelloy, titanium or a nickel-based alloy with high strength and high corrosion resistance, and made of stainless steel or a steel material having a plating film on the outer surface of the outer tube (1) is coated. A high-pressure fuel injection pipe characterized by being worn. 3. A cap-like collar (5) made of a metal material having a communication hole (5 ') formed on the top surface is attached to the pressing surface (1 ") formed by the connecting head (1'). At the same time, a contact engagement portion formed by the hole circumference of the communication hole (5 ') of the collar and the tip circumference (3') of the inner pipe (3) is formed.
2. The electrodes are formed by welding (6) to each other.
Alternatively, the high-pressure fuel injection pipe according to item 2. 4. The outer skin tube (4) is attached to the connection head (1 ') by extending the connection head (1') slightly to the near side of at least under the neck,
The high-pressure fuel injection pipe according to claim 2 or 3, wherein the high-pressure fuel injection pipe is formed.