JPS5852370Y2 - Pipe end head connection structure of high pressure fuel injection pipe - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in the tube end head connection structure of a relatively small-diameter high-pressure fuel injection tube with a tube diameter of about 20 mm or less, which is disposed as a fuel supply tube for a diesel internal combustion engine.

In general, the suppression sheet surface that forms the front surface of the pipe end head of a high-pressure fuel injection pipe is pressed into contact with the bottom surface of the other nozzle holder from the lower end of the suppression sheet surface to the midway point, in order to ensure pressure contact at the tip. The outside portion is configured so as not to come into contact with the open face of the nozzle holder.

By the way, as shown in FIG. 3, in the conventional pipe end head connection structure, when fastening, the back surface of the connection head 12 is brought into full contact engagement with the front surface of the flange 14 of the sleeve washer 13, and the flange 14 of the sleeve washer The structure is such that the entire back surface of the NAND is brought into contact with the tightening nut 15, so if the NAND is strongly tightened during connection, there will be a forward movement near the outer periphery of the connection head that is not in contact with the nozzle holder seating surface. In addition to causing pressure deformation, there is a tendency to generate tensile stress near the bottom of the head and neck of the tube body 11. Also, if there are variations in the bending shape or defects on the tube side as a finished product, the suppression sheet surface may be unevenly touched. Forcing the above-mentioned full-surface abutment engagement with excessive tightening, such as the It was one of the causes of this.

This invention solves this problem very effectively with a simple structure, and even if excessive tightening force is applied, pressing force is applied to the non-contact and engaged portion of the suppression sheet surface of the connection head. The present invention provides a tube end head connection structure that can eliminate complicated stress concentration near the bottom of the head and neck by preventing it from occurring.

The present invention will be described in detail with reference to the drawings below. 1 is a metal tube whose front end is a suppressing sheet surface 1' and a bulging connection head 2 is integrally formed at the end; 3 is a metal tube whose front end is connected to the back surface of the connection head. A sleeve washer 5 has a matching flange 4 and is press-fitted onto the outer peripheral surface near the bottom of the neck of the connecting head, and 5 engages with the back side of the flange of the sleeve washer to connect the connecting head 2 to the open opening of the mating nozzle holder 6. The tightening that presses against the surface is Nando.

The tube end head connection structure of the present invention is such that the front surface of the flange 4 of the sleeve washer 3 is brought into contact with the rear surface of the connecting head 2 in a direction approximately perpendicular to the tube axis, and the rear surface of the 7 lumps 4 of the sleeve washer 3 are fastened together. A minute gap I is formed along the outer circumferential side of at least one of the abutting engagement surfaces of the attached nut 5,
Thereby, the non-engaging portion is held on the outer circumferential side of one of the abutting and engaging surfaces during pressure engagement.

In the embodiment shown in FIG. 1, by tilting the outer circumferential side of the back surface of the connecting head 2 forward, a minute gap (non-engaging In the embodiment shown in FIG. 2, the outer periphery of the back surface of the sleeve one flange 4 is inclined forward, so that the outer periphery of the abutment and engagement surface between the back surface of the flange 7 and the tightening nut 5 is increased. A minute gap 7 is provided on the side.

As described above, in the present invention, the non-contact portion is held along the outer periphery of the abutment and engagement surface of at least one of the front surface of the sleeve washer and the back surface of the connection head, or the back surface of the sleeve washer and the tightening nand. Since the gap is formed, the pressing force toward the outer periphery of the connection head that is not in contact with the seat surface of the nozzle holder, that is, the outer side of the engaging end 8 with the nozzle holder is significantly reduced.

Therefore, even if the connection is excessively tightened with force, there will be no forward pressure deformation near the outer periphery of the connection head and associated tensile stress near the bottom of the head and neck. Due to variations in the side bending shape and defects,
Even if unreasonable tightening such as one-sided contact is applied to the suppression sheet surface, the connecting head engages at a relatively small diameter portion, so the complex concentration of stress on the lower part of the head and neck is significantly reduced, and these synergistic effects As a result, it is possible to effectively prevent cracks and breakage accidents caused by fatigue in the area below the head and neck.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional view showing the connection state of the tube end head connection structure of a high-pressure fuel injection pipe according to an embodiment of the present invention, FIG. 2 is a view equivalent to FIG. 1 according to another embodiment of the present invention, FIG. 3 is a diagram corresponding to FIG. 1 according to a conventional embodiment. 2... Connection head, 3... Sleeve washer, 4... Sleeve washer flange, 5
...Tighten with NAND, 7...Minute gap.

Claims (1)

[Scope of utility model registration request] The end of the metal tube has a flange that abuts and engages with the back surface of the connection head near the back neck of the connection head whose front surface is integrally formed as a sheet surface that abuts and presses against the open opening surface of the other nozzle holder. In a tube end head connection structure in which a sleeve washer is press-fitted and a tightening nut is abutted and engaged with the back surface of the flange of the sleeve washer, the back surface of the connection head 2 in a direction approximately perpendicular to the tube axis and The front surface of the flange 4 of the sleeve washer 3 and the rear surface of the flange 4 of the sleeve washer 3 are tightened in a non-engaging manner along the outer periphery of at least one of the abutment and engagement surfaces of the NAND 5. A pipe end head connection structure for a high-pressure fuel injection pipe, characterized in that a minute gap T is formed for holding a joint part.