JP3367215B2 - Fuel injection nozzle and method of assembling the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fastening structure between a holder body and a connecting pipe in a fuel injection nozzle for an internal combustion engine and a method for assembling the fuel injection nozzle.

[0002]

2. Description of the Related Art In a fuel injection nozzle for an internal combustion engine, a nozzle is attached to one end of a holder main body, and a hole for taking out leaked fuel from a spring chamber of the holder main body is provided at the other end of the holder main body. A connecting pipe forming a fuel passage is attached, a high-pressure fuel passage in the connecting pipe communicates with a high-pressure fuel passage in the holder body, and a low-pressure fuel passage in the connecting pipe leaks from the spring chamber of the holder body to remove the fuel. Communicate with the hole. The fuel from the high-pressure fuel passage is injected from the nozzle when the valve opens due to the fuel pressure against the spring. Fuel leaking into the spring chamber is taken out of the adapter via the low pressure fuel passage.

The connection between the connecting pipe and the holder body is performed by screwing the connecting pipe into the holder body. In this case, the connecting pipe is arranged so as to intersect with the low pressure fuel passage from the spring chamber to the adapter, and it is necessary to seal the high pressure fuel passage in the connecting pipe and the low pressure fuel passage in the holder body. In view of this, in Japanese Patent Publication No. 57-38783, an O-ring is provided at the threaded connection portion of the connecting pipe to the holder body so as to sandwich the low pressure fuel passage, and the high and low fuel passages are oil-tight.

[0004]

Recently, four valves are the mainstream of internal combustion engines, but with this, there is no room in the mounting space, and there is a demand for smaller nozzles. Due to the miniaturization of the nozzle, it becomes difficult to secure the nozzle diameter for obtaining the required tightening torque. Therefore, there is a possibility that fuel may leak from the seal portion due to a decrease in tightening torque due to loosening. Further, the nozzle is mounted in the cylinder head with the shift to four valves, but in this case, the seal portion is exposed to a high temperature atmosphere in the cylinder head, and there is a possibility that leakage may occur in the seal portion due to deterioration of the O-ring. .

In order to solve this problem, it is conceivable that the holder main body and the connecting pipe are made into an integral structure by forging or the like, but in this case, it is necessary to process the fuel hole by two axes of the holder main body and the connecting pipe. There is
There is a problem in workability. In view of the above-mentioned problems of the prior art, the present invention ensures the strength of the joint portion with the connecting pipe with respect to the downsizing of the holder body, and does not deteriorate the sealing property even in a high temperature atmosphere, and An object of the present invention is to provide a structure of a fuel injection nozzle in which a fuel hole can be easily processed and an assembling method thereof.

[0006]

According to the first aspect of the invention, a nozzle is attached to one end of the holder body, and a hole for taking out leaked fuel from the spring chamber of the holder body is provided at the other end. A connecting pipe having a passage for high pressure fuel is attached to the main body, the high pressure fuel passage in the connecting pipe communicates with the high pressure fuel passage in the holder body, and the low pressure fuel passage in the connecting pipe defines the spring chamber of the holder body. In the fuel injection nozzle communicating with the leaked fuel extraction hole, the high-pressure fuel passage in the holder main body to the high-pressure fuel passage of the connecting pipe is extended from the lower end surface of the holder main body in parallel with the axis of the holder main body,
A fuel injection nozzle is provided, wherein the low-pressure fuel passage of the connecting pipe extends between the spring chamber and the adapter along an axial direction of the holder body.

According to the second invention, the nozzle is attached to one end of the holder main body, and the hole for taking out the leaked fuel from the spring chamber of the holder main body is provided at the other end. A connecting pipe having a passage is attached, a high-pressure fuel passage in the connecting pipe communicates with a high-pressure fuel passage in the holder body, and a low-pressure fuel passage in the connecting pipe communicates a spring chamber of the holder body with the adapter. In the nozzle, at least the high-pressure fuel passage of the high-pressure fuel passage of the connecting pipe and the low-pressure fuel passage of the low-pressure fuel passage is drilled from the end face of the holder main body by a drilling tool after joining the connecting pipe to the holder main body. An assembly method is provided.

[0008]

In the structure of the fuel injection nozzle of the present invention,
The high-pressure fuel passage and the low-pressure fuel passage are formed by joining the connecting pipe to the holder body at the time of assembly and then introducing a drilling tool from the lower end surface of the holder body to perform the drilling work.

[0009]

EXAMPLE In FIG. 1, a nozzle body 2 is attached to the lower end of a substantially columnar holder body 1. The holder main body 1 has a high-pressure fuel passage 3 formed therein in parallel to and spaced from the center line thereof.
To a fuel pressure chamber (not shown) formed in the nozzle body, and the fuel pressure in the fuel pressure chamber urges the needle (not shown) in the nozzle body 2 to open. A spring chamber 4 is formed along the center line in the holder body 1, and a coil spring 5 is arranged in the spring chamber 4, and the coil spring 5 biases the needle to close the valve.
When the fuel pressure in the fuel pressure chamber overcomes the set force of the spring, the needle opens and the fuel is injected from the nozzle 6 at the tip of the nozzle body 2.

The holder body 1 has a horizontal through hole 7 formed above the spring chamber 4, and a substantially cylindrical connecting pipe 10 is inserted into the through hole 7 for high sealing performance such as roasting. Moreover, they are firmly joined by a joining means having high heat resistance. The connecting pipe 10 has a filter mounting hole 12 extending from one end thereof in the direction of the center line, and a bar filter 14 (a filter is not always necessary) is mounted in the filter mounting hole 12. The filter mounting hole 12 is connected to a pipe for receiving high-pressure fuel pumped from a fuel injection pump (not shown), and the bar filter 14 removes foreign matters in the supplied fuel. From the bottom surface of the filter mounting hole 12, a high-pressure fuel passage 16 having a small diameter is provided.
Extend part way along the center line, and from there, a part 16 ′ of the high pressure fuel passage 16 is formed so as to be orthogonal to the center line.
Turns to reach the outer peripheral surface of the connecting pipe 10. On this outer peripheral surface, the high pressure fuel passage 16 of the connecting pipe 10 is connected to the high pressure fuel passage 3 of the holder body 1.

A low-pressure fuel passage 20 extends from the spring chamber 4 of the holder main body 1 along the center line thereof, and the passage 20 intersects with the through hole 7 for attaching the connecting pipe,
It reaches the adapter mounting hole 22 at the upper end of the holder body 1. The leaked fuel extraction adapter 2 is inserted into the adapter mounting hole 22.
4 is attached by screwing. The adapter 24 has a hole 26 formed therein for taking out leaked fuel. On the other hand, the connecting pipe 10 forms a low-pressure fuel passage 28 in a direction orthogonal to the center line thereof, and the low-pressure fuel passage 28 in the connecting pipe 10 and the low-pressure fuel passage 20 in the holder body 1 form a single unit. A passage is formed so that fuel leaking into the spring chamber 4 can be taken out from the adapter 24 to the outside.

FIG. 2 shows a method of assembling the fuel injection nozzle of FIG. The connecting pipe 10 is inserted into the through-hole 7 of the holder body 1, and the connecting pipe 10 is joined to the holder body 1 by a joining means having a strong sealing property such as rotting. Whether or not the filter material is securely attached can be judged by visually observing whether the filter material is permeating from the surface on the opposite side of the filter material. At this stage, the portions of the high-pressure fuel passages 3 and 16 'and the portions of the low-pressure fuel passages 20 and 28 in FIG. 1 are unformed and remain intact.

After the completion of the joining by the filter material, the holder body 1
1. The portions of the high pressure fuel passages 3 and 16 'of FIG. That is, the boring tool D is used to perforate the holder body 1 to the path 16 of the connecting pipe. In addition, the drilling tool D is introduced into the spring chamber 4 along the center line m of the holder body, and the hole is drilled up to the adapter mounting hole 22 including the holder body 1 and the portion of the connecting pipe 10 inserted therein. . As a result, the passages 20 and 28 of FIG. 1 are formed. Since the holder body 1 and the connecting pipe have a substantially cylindrical shape, they can be mounted on a lathe to easily perform the working operation.

FIG. 3 shows a second embodiment. In the second embodiment, a ring-shaped groove 100 is formed on the outer circumference of the connecting pipe 10, and the low-pressure fuel passage 20 on the holder body 1 side is opened in this groove 100 so that leaked fuel from the spring chamber 4 is directed to the adapter 24 side. Is leading. FIG. 4 shows the holder body 1 and the connecting pipe 10 before assembly in the case of the second embodiment. In this case, unlike the first embodiment, the low-pressure fuel passage 20 is already drilled before assembly. When the connecting pipe 10 is inserted into the through hole 7 of the holder body 1, the filter medium is placed in the ring-shaped groove 100. By inserting the connecting pipe 10 into the through hole 7 of the holder main body 1 and then performing a filtering operation, the filter material permeates the joint surface between the connecting pipe 10 and the holder main body 1 and permeates to flow out from the end surface to permeate. The situation can be visually confirmed. After the completion of the roasting, the drilling tool D is introduced from the lower end surface of the holder main body 1 and penetrates the holder main body 1 to pass the connecting pipe passage 16 as in the first embodiment.
Perform drilling work up to the part.

[0015]

According to the present invention, at least the high-pressure fuel passage is formed by joining the connecting pipe to the holder body and then introducing the punching tool from the end surface of the holder body to perform the punching operation. Therefore, for joining, a strong joining means such as heat-resistant brazing can be adopted, and strong joining can be obtained without fear of thermal deterioration. Therefore, sufficient bonding strength can be obtained even if the diameter of the nozzle is reduced.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a fuel injection nozzle of the present invention.

FIG. 2 is a vertical cross-sectional view showing the holder body of the fuel injection nozzle and the connecting pipe of the present invention immediately after they are joined and before they are punched.

FIG. 3 is a vertical sectional view similar to FIG. 1 but showing another embodiment.

FIG. 4 is a vertical cross-sectional view showing a holder body and a connecting pipe in a second embodiment in a state immediately after joining and before drilling.

[Explanation of symbols]

1 ... Holder body 2 ... Nozzle body 3 ... High-pressure fuel passage 4 ... Spring chamber 10 ... Connecting pipe 16 ... High-pressure fuel passage 20 ... Low-pressure fuel passage 26 ... Leakage fuel outlet 28 ... Low-pressure fuel passage 100 ... Ring groove

Front page continuation (58) Fields surveyed (Int.Cl. ⁷ , DB name) F02M 61/10 F02M 61/16 F02M 55/02 330

Claims (4)

(57) [Claims] 1. A connecting pipe in which a nozzle is attached to one end of a holder body, a hole for taking out leaked fuel from a spring chamber of the holder body is provided at the other end, and a passage for high pressure fuel is formed in the holder body. Is attached, the high pressure fuel passage in the connecting pipe is communicated with the high pressure fuel passage in the holder body, the low pressure fuel passage in the connecting pipe is a fuel injection nozzle that communicates the spring chamber of the holder body with the leakage fuel extraction hole, The high-pressure fuel passage in the holder main body to the high-pressure fuel passage of the connecting pipe extends from the lower end surface of the holder main body in parallel with the axis of the holder main body, and the low-pressure fuel passage of the connecting pipe includes a spring chamber and an adapter. The fuel injection nozzle is characterized in that it is provided along the axial direction of the holder main body. 2. The fuel injection nozzle according to claim 1, wherein the connecting pipe has a ring-shaped groove on the outer circumference thereof, and the low-pressure fuel passage of the holder main body is open to the ring-shaped groove. 3. A connecting pipe in which a nozzle is attached to one end of the holder main body, a hole for taking out leaked fuel from a spring chamber of the holder main body is provided at the other end, and a passage for high pressure fuel is formed in the holder main body. Is attached, the high-pressure fuel passage in the connecting pipe communicates with the high-pressure fuel passage in the holder body, and the low-pressure fuel passage in the connecting pipe connects the spring chamber of the holder body to the adapter in the fuel injection nozzle. At least the high-pressure fuel passages of the high-pressure fuel passage and the low-pressure fuel passage are drilled from the end face of the holder body by a punching tool after the connecting pipe is joined to the holder body. 4. The method according to claim 3, wherein the joining of the connecting pipe to the holder body is performed by rotting.