JPH027258Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a high-pressure fuel injection pipe for a diesel engine or the like, and particularly relates to an improvement in the end structure connected to a fuel injection pump or a fuel injection nozzle.

For example, in the case of a diesel engine, as shown in FIG. High pressure fuel is supplied to the injection nozzle 2. Figure 2 shows
The above fuel injection pump 1 or fuel injection nozzle 2
This figure shows a conventional end structure of the fuel injection pipe 3 that is detachably connected to the fuel injection pipe 3, and a head 4 is formed at the tip of the fuel injection pipe 3 to have a larger diameter than the general part of the injection pipe 3. At the same time, this head 4 is fastened to the fuel injection pump 1 etc. via a sleeve 5 with an annular fixing screw 6. That is, the head 4
has a tapered surface 4a that can be tightly fitted to the fuel outlet of the fuel injection pump 1 or the fuel inlet of the fuel injection nozzle 2, and has a shoulder portion 4b for positioning the sleeve 5. The flange portion 5a at the tip of the sleeve 5, which is rotatably fitted onto the outer periphery of the pipe 3, abuts and engages with the shoulder portion 4a, and the fixing screw 6, which is rotatably fitted onto the outer periphery of the sleeve 5, is attached to the fuel injection pump. 1 or the fuel injection nozzle 2, the head 4 is firmly crimped through the flange 5a.

In such a conventional end structure, when focusing on the bending rigidity of the fuel injection pipe 3, even if the pipe diameter is the same, the bending rigidity is high in the area _l1 reinforced by the sleeve 5, and In the exposed range _l2 , the bending rigidity is much lower than this, and an extreme difference in rigidity occurs at the boundary A between the two. Therefore, when the fuel injection pipe 3 resonates due to vibration input from the engine body (not shown) or pressure fluctuations within the fuel injection pipe 3, stress concentrates on the boundary A, causing damage due to repeated fatigue. There were fears that this would lead to

In addition, in order to prevent damage due to such stress concentration, conventionally, as shown in Fig. 3, the pipe diameter _D1 at the end of the fuel injection pipe 3 is made one step larger than the pipe diameter _D2 at the general part. There is an example in which the pipe diameter is changed smoothly at a position slightly protruding from the sleeve 5 to avoid an extreme difference in bending rigidity that would cause stress concentration, but in reality, machining is difficult. It was difficult and difficult to put it into practical use in terms of cost.

This idea was devised in view of the conventional problems mentioned above, and its purpose is to reliably prevent damage caused by the stress concentration mentioned above without performing complicated processing on the fuel injection pipe itself. An object of the present invention is to provide an end structure for a fuel injection pipe.

That is, the end structure of the fuel injection pipe according to this invention is such that the tip of the fuel injection pipe has a bulge having a larger diameter than the general part of the injection pipe, and is fitted into the fuel inlet/outlet of the fuel injection pump or the fuel injection nozzle. a sleeve that is fitted into the fuel injection pipe and whose tip flange engages with the head; and a sleeve that is rotatably fitted onto the outer circumference of the sleeve and screwed onto the fuel injection pump or fuel injection nozzle. an annular fixing screw; and a plurality of slits that are formed along the axial direction of the sleeve at the proximal end of the sleeve extending so as to protrude from the fixing screw, and that are open at the proximal end of the sleeve. It is characterized by the fact that it is equipped with

A specific embodiment of this invention will be described below with reference to the drawings.

FIG. 4 shows the end structure of the fuel injection pipe according to this invention, and since its basic structure is substantially the same as that in FIG. 2, the same parts are given the same reference numerals. That is, the head 4 bulging at the tip of the fuel injection pipe 3 has a tapered surface 4a that can be tightly fitted to the fuel outlet of the fuel injection pump or the fuel inlet of the fuel injection nozzle, and also positions the sleeve 5. The fuel injection pipe 3 is formed to have the same diameter except for the head 4. In addition, on the outer periphery of the fuel injection pipe 3,
A sleeve 5 having a flange portion 5a that abuts the shoulder portion 4b is rotatably fitted, and an annular fixing screw 6 that can be screwed onto a fuel injection pump or a fuel injection nozzle is rotatably attached to the outer periphery of the sleeve 5. It is inserted freely. Here, the sleeve 5 is
Its base end 5b is formed to extend relatively long, and is several mm to several tens of mm from the base end of the fixing screw 6.
It protrudes to a certain extent, and at this base end 5b,
A plurality of slits 7 are formed along the axial direction of the sleeve 5. The slit 7 has a starting point at a position slightly protruding from the proximal end surface of the fixing screw 6, and the other end is open to the proximal end of the sleeve 5. A circular hole 8 is provided to prevent this from occurring.

According to the structure in which the slit 7 is formed in the sleeve 5 as described above, the bending rigidity of the sleeve 5 is weakened by the slit 7. Therefore, when focusing on the bending rigidity of the fuel injection pipe 3 combined with this sleeve 5, the part B protruding from the fixing screw 6, the starting point C of the slit 7, and the sleeve 5
The bending rigidity gradually decreases at the point D protruding from the sleeve 5, and furthermore, the bending rigidity gradually decreases in the area of the sleeve 5 having the slit 7, so that there is no place where an extreme difference in rigidity occurs. Therefore, the vibration input from the engine body causes the fuel injection pipe 3 to
Even if there is resonance vibration, local stress concentration does not occur unlike in the conventional case, and damage to the fuel injection pipe 3 due to this can be reliably prevented. In particular, in the structure in which the slit 7 is formed as described above, the sleeve 5 is divided into a plurality of pieces by the slit 7, and only some of the pieces can be deformed, resulting in large deformation. It can also exhibit good effects against low frequency vibrations. In other words, the absorption frequency band for bending resonance becomes extremely wide. Moreover, since each piece divided into a plurality of pieces can also be deformed in the circumferential direction, a vibration absorption effect can be obtained even against torsional vibration, and damage to the fuel injection pipe 3 can be more reliably prevented. Furthermore, when assembling into a fuel injection pump or the like, only a portion of the plurality of divided pieces can be deformed, so there is an advantage that assembling becomes easy.

As explained above in detail, according to the end structure of the fuel injection pipe according to this invention, damage to the fuel injection pipe due to local stress concentration can be reliably prevented, and the fuel injection pipe itself has special features. Since no processing is required, it can be implemented at low cost. In particular, the sleeve is divided into multiple pieces due to the formation of the slits, and only some of the pieces can be deformed, allowing for large deformations and preventing bending resonance in a wide vibration frequency range, including low frequencies. At the same time, it is possible to absorb torsional vibrations, and the workability during assembly is also good.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram schematically showing the main parts of the fuel system of a diesel engine, Fig. 2 is a sectional view showing the end structure of a conventional fuel injection pipe, and Fig. 3 is a sectional view showing a different conventional example. 4 are half-sectional views showing the end structure of the fuel injection pipe according to this invention. 3... Fuel injection pipe, 4... Head, 5... Sleeve, 5a... Flange portion, 5b... Base end, 6...
...Fixing screw, 7...slit.

Claims (1)

[Scope of utility model registration request] A head which is formed at the tip of the fuel injection pipe to have a larger diameter than the general part of the injection pipe and which fits into the fuel inlet/outlet of the fuel injection pump or the fuel injection nozzle; a sleeve whose flange portion engages with the head; an annular fixing screw rotatably fitted onto the outer periphery of the sleeve and screwed onto a fuel injection pump or a fuel injection nozzle;
A plurality of slits formed along the axial direction of the sleeve and open at the base end of the sleeve are provided at the base end of the sleeve extending so as to protrude from the fixing screw. End structure of fuel injection pipe.