JPH03117670A - Fuel injection device - Google Patents

Abstract

PURPOSE:To achieve reliable joining as a bearing is reduced by a method wherein the joint of the end part of an injection pipe is contact-bonded and connected to the connection part of a fuel injection nozzle or a fuel injection pump by means of a retainer. CONSTITUTION:In connection between an injection pipe 15 and a connection part 20 of a fuel injection nozzle or a fuel injection pump, a flangeform protrusion 21 is formed on the tip part of the injection pie 15. A protection ring 22 is located at the shoulder part of the protrusion part 21, a retainer 23 is fastened against a male screw 24 of the connection part 20, and by means of the fastening force, a tip joint 25 of an injection pipe 15 is contact-bonded to the bottom surface of a recessed part 26 of the connection part 20. This constitution achieves reliable joining as a bearing is reduced and prevents deformation and wear of the connection part on the tip side of the injection pipe.

Description

[Detailed description of the invention]

TECHNICAL FIELD The present invention relates to a fuel injection device, and in particular to a fuel injection device, in which fuel is pressurized by a fuel injection pump, the pressurized fuel is supplied to a fuel injection nozzle through an injection pipe, and the fuel is injected from the injection port of the fuel injection nozzle. A device configured to inject fuel,
This invention relates to an improvement in the joint structure of the injection pipe.

[Summary of the invention]

A joint surface is formed at the end of the injection pipe that is substantially perpendicular to its axial direction, and this joint surface is crimped to the joint surface of the connection part of the fuel injection nozzle or fuel injection pump using a retainer to perform the connection. It has a connection structure that can withstand high-pressure injection.

[Conventional technology]

In a diesel engine, fuel is pressurized by a fuel injection pump, and the pressurized fuel is supplied to a fuel injection nozzle by an injection pipe. The fuel injection nozzle has its injection port opened by fuel pressure, and a spray of fuel is injected into the cylinder. As shown in FIG. 3, the injection pipe 1 interposed between the fuel injection pump and the fuel injection nozzle is connected to the connection part 2 of the fuel injection nozzle or the fuel injection pump by a retainer 3. The retainer 3 presses the shoulder of the protrusion 5 through the protective ring 4, so that the conical part 6 on the distal end side of the injection pipe 1 is pressed into the tapered hole 7 of the connecting part 2. KProblems to be Solved by the Invention In order to achieve high-pressure injection by increasing the fuel pressure by the fuel injection pump, it is necessary to supply high fuel pressure to the fuel injection nozzle through the injection pipe 1. Therefore, in such a case, the retainer 3 must be tightened with a high force to prevent leakage. However, when a large force is applied to the shoulder of the protrusion 5 on the tip side of the injection tube 1 by the retainer 3, the conical portion 6 on the tip side of the protrusion 5 becomes stepped, as shown in FIG. This will cause wear. This causes fuel leakage during high pressure injection. In addition, the tightening indicated by the arrow causes the distal end portion of the injection pipe 1 to be deformed so as to be compressed by the tapered hole 7 due to the force 8, and the opening on the distal end side of the injection pipe 1 is narrowed. . Therefore, the fuel pressure will drop at the throttled portion, resulting in a problem that high pressure injection will not be performed. The present invention has been made in view of these problems, and it is possible to prevent wear and deformation of the injection pipe at the connection between the injection pipe and the fuel injection nozzle or fuel injection pump, and to prevent liquid leakage. The object of the present invention is to provide a fuel injection device that can withstand high-pressure injection. Means for Solving Problem K] The present invention pressurizes fuel with a fuel injection pump, supplies the pressurized fuel to a fuel injection nozzle through an injection pipe, and injects the fuel from the injection port of the fuel injection nozzle. In the apparatus, a joint surface that is substantially perpendicular to the axial direction of the injection pipe is formed at the end of the injection pipe and the connection part with the fuel injection nozzle or the fuel injection pump, and the joint surface is formed by a retainer. The connection is made by being press-fitted to the joint surface of the connection portion of the fuel injection nozzle or the fuel injection pump. K effect] Therefore, even if the joint formed at the end of the injection pipe is strongly tightened with a retainer to withstand high-pressure injection, the joint surface is almost perpendicular to the axial direction, so it will not wear out or deform. This makes it possible to reliably connect with a large surface pressure.

【Example】

FIG. 2 shows a diesel engine 10 equipped with a fuel injection device according to an embodiment of the present invention, and a fuel injection pump 11 is attached to the side surface of the cylinder block of the engine 10. As shown in FIG. The fuel injection pump 11 is provided with a camshaft 12, and a timer 13 is attached to the camshaft 12 to adjust the timing of injection. The fuel injection pump 11 is also equipped with a mechanical governor 14, which adjusts the amount of fuel injected at one time. Each pump unit of the fuel injection pump 11 is connected to a fuel injection nozzle 16 via an injection pipe 15. Therefore, when the camshaft 12 is driven by the output of the engine 10 via the timer 13, the fuel injection pump 11
Each pump unit will periodically pressurize the fuel. The amount of pressurized fuel supplied is adjusted by a mechanical governor 14. The pressurized fuel is then supplied to the fuel injection nozzle 16 through the injection pipe 15, and a spray of fuel is injected into the cylinder from the injection port of the nozzle 16. The intake air taken into the cylinder is pressurized by the piston and becomes hot.
The fuel spray is spontaneously ignited and combusted by the heat of the intake air, thereby causing the engine 10 to generate output. Next, the structure of the connection between the injection pipe 15 and the fuel injection nozzle 16 or the connection between the injection pipe 15 and the fuel injection pump 11 will be explained. FIG. 1 shows the structure of the connection between the injection pipe 15 and the connection part 20 of the fuel injection nozzle 16,
Seven flange-like protrusions 21 are formed at the tip of the injection pipe 15. Then, the shoulder part of this protrusion 21 is covered with a protective ring 2.
2 and is pressed by a retainer 23. The retainer 23 has a female thread on its inner peripheral surface,
It is adapted to be screwed into the male thread 24 of the connecting portion 20. This tightening is performed so that the joint surface 25 on the distal end side of the injection pipe 15 is pressed against the bottom surface of the recess 26 by force. That is, in the fuel injection device according to this embodiment, the structure of both ends of the high-pressure injection pipe 15 is changed from a conical projection 6 to a cylindrical projection as shown in FIG. A surface perpendicular to the axial direction is used as a joint surface 25 to achieve precise finishing. The contact between the connecting portion 20 and the concave portion 26 is made of metal to improve airtightness against fuel, and the tightening by the retainer 23 provides rigidity against force. According to such a structure, the surface pressure of the joint surface 25 is reduced, deformation is prevented, and wear is also reduced. In addition, when tightening the retainer 23, the force acts on the joint surface 25 perpendicular to the axial direction, so the tip of the injection pipe 15 is not narrowed toward the center in the radial direction, and the fuel pressure passing through the injection pipe 15 is reduced. There will be no descent. High-pressure injection of fuel is a suitable technology for improving diesel engine exhaust emissions. In this case, the injection pipe 15
Leakage from the tube 15 and increased stiffness of the tube 15 become important overages. In line with this purpose, as shown in FIG. By using force to press the joint surface 25 into the recess 26 of the connection part 20, increasing rigidity and preventing leakage, problems such as fuel leakage, deformation of the injection pipe, and wear of the connection part, which are conventional, are avoided. becomes possible to eliminate.

【Effect of the invention】

As described above, the present invention forms a joint surface substantially perpendicular to the axial direction of the injection pipe at the end of the injection pipe and the connection part with the fuel injection nozzle or fuel injection pump, and this joint surface is connected to the fuel injection pipe using a retainer. The connection is made by pressing onto the joint surface of the connection part of the injection nozzle or fuel injection pump. Therefore, according to such a structure, the tightening by the retainer becomes a pressing force that presses the joint surface of the end of the injection pipe, which is substantially perpendicular to the axial direction, to the joint surface of the connection part of the fuel injection nozzle or fuel injection pump. , it is possible to achieve reliable joining while reducing the surface pressure, and it is possible to prevent deformation and wear of the connection portion on the tip side of the injection pipe.

[Brief explanation of drawings]

FIG. 1 shows a jet engine according to an embodiment of the present invention. 2 is a side view showing the overall structure of a diesel engine; FIG. 3 is an enlarged vertical sectional view of main parts showing a conventional injection pipe connection structure; FIG. 4 is an enlarged front view showing the behavior of deformation due to force when tightening a conventional injection pipe. The names of the main parts in the drawings are as follows. DESCRIPTION OF SYMBOLS 11...Fuel injection pump 15...Injection pipe 16...Fuel injection nozzle 20...Connection part 21...7 Lunge-like projection 22...Protection ring 23...Retainer 24... Male thread 25...Joint surface 26...Concave part

Claims (1)

[Claims] 1. Pressurize the fuel with a fuel injection pump, and
In a device that supplies pressurized fuel to a fuel injection nozzle through an injection pipe and injects the fuel from a nozzle of the fuel injection nozzle, an end portion of the injection pipe that is connected to the fuel injection nozzle or the fuel injection pump is provided. A joint surface that is substantially perpendicular to the axial direction of the injection pipe is formed at the connection part of the fuel injection nozzle or the fuel injection pump, and the joint surface is crimped to the joint surface of the connection part of the fuel injection nozzle or the fuel injection pump using a retainer to perform the connection. A fuel injection device characterized by: