JP2003139016A - Sliding part wear reducing structure for fuel injection valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sliding part wear reducing structure for a fuel injection valve for reducing the aging effect of a fuel injection amount to permit the reduced wear of a nozzle needle 4 in a clearance hole 18 in a nozzle body 3, in particular, by preventing the turn-down of the nozzle needle 4 and a valve piston 15 from their axial directions to their radial directions. SOLUTION: A focal point is that a sleeve 24 is provided on a joint 22 between a valve piston 15 and the nozzle needle 4 for connecting the valve piston 15 and the nozzle needle 4 to be guided. The sleeve 24 is provided on the joint 22 between the nozzle needle 4 and the valve piston 15 for preventing the turn- down of the nozzle needle 4 and the valve piston 15 from their axial directions following the lift and seat of the nozzle needle 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for reducing sliding portion wear in a fuel injection valve, and more particularly to a slide in a fuel injection valve for injecting high pressure fuel supplied from a pressure accumulator (common rail) or the like at a predetermined timing. The present invention relates to a moving part wear reduction structure.

[0002]

2. Description of the Related Art A conventional fuel injection valve will be outlined with reference to FIGS. FIG. 3 is a vertical cross-sectional view of the fuel injection valve 1, and FIG. 4 is an enlarged cross-sectional view of the same. FIG. 4 is a cross-sectional view of the fuel injection valve 1.
And a nozzle needle 4 and a back pressure control unit 5.

A nozzle body 3 is attached to the tip of the injector housing 2 by a nozzle nut 6, and a back pressure control section 5 is provided above the nozzle body 3. The high-pressure fuel is supplied to the fuel injection valve 1 from the common rail 7 (pressure accumulator) that stores the high-pressure fuel. That is, the fuel passage 8 is formed across the injector housing 2 and the nozzle body 3, and the fuel reservoir chamber 9 is formed facing the pressure receiving portion 4A (FIG. 4) of the nozzle needle 4, and the fuel reservoir chamber 9 and the nozzle body 3 are separated from each other. High pressure fuel from the common rail 7 can be constantly supplied to the tip portion.

An arbitrary number of fuel injection holes 10 are formed at the tip of the nozzle body 3, and the tip of the nozzle needle 4 seats on the seat portion 11 connected to the injection hole 10 to close the injection hole 10. The nozzle needle 4 is seated on the seat 1.
By lifting from 1, the injection hole 10 is opened and fuel can be injected.

A spring chamber 12 is provided in the center of the injector housing 2 above the nozzle needle 4.
(First sliding hole) is formed to contact the intermediate 13 as a spring seat, the nozzle spring 14 for urging the nozzle needle 4 toward the seat 11 in the seat direction, and the intermediate 13 from above. And a valve piston 15.

The valve piston 15 has a spring chamber 12
A long rod-shaped member extending from the portion to the upper portion of the injector housing 2, and is inserted into the central hole 16 in the injector housing 2 with a gap between the inner wall surface and the central hole 16 and the uppermost portion thereof is used for back pressure control. It is guided in the valve body 17 of the portion 5, and the lowermost portion thereof is in contact with the intermediate 13 as described above. By controlling the valve piston 15 by the back pressure control unit 5, that is, by controlling the back pressure of the nozzle needle 4, the seat and lift of the nozzle needle 4 are controlled via the intermediate 13.

The upper portion of the nozzle needle 4 is slidable in the clearance seal hole 18 (second sliding hole) of the nozzle body 3. The nozzle body 3 has a clearance seal hole 18 separating the high pressure side (fuel storage chamber 9) and the low pressure side (spring chamber 12).

In the fuel injection valve 1 having such a structure, the valve piston 15 driven and controlled by the back pressure control unit 5 lifts or seats the nozzle needle 4 through the intermediate 13, and the fuel injection amount from the injection hole 10 And the injection timing is controlled,
As a result of each injection, the intermediate 13 slightly falls in the spring chamber 12 of the injector housing 2 in the axial direction, and the nozzle needle 4 slightly falls in the clearance seal hole 18 of the nozzle body 3 in the axial direction. There is a problem that friction occurs between the injector housing 2 and the inner wall surfaces of the nozzle body 3, and the sliding portions of the injector housing 2 and the nozzle body 3 are worn to cause changes in the injection characteristics of the fuel injection valve 1 over time. In FIG. 4, a clearance hole 1 in the injector housing 2 between the spring chamber 12 and the intermediate 13 and in the nozzle body 3
8 and the nozzle needle 4 have a sliding portion where wear occurs along the dotted line in the figure (first around the intermediate 13).
19A and a second sliding portion 19B) around the nozzle needle 4 are shown. Intermediate 13
Alternatively, when the nozzle needle 4 falls down from the respective axial directions, the first sliding portion 19A and the second sliding portion 19B cause pressure contact with the spring chamber 12 and the inner wall surface of the clearance hole 18, and the respective sliding portions 19A and 19B are brought into contact with each other. There is a problem that abrasion occurs between them.

Particularly, the fuel injection valve 1 of the type having the common rail 7 is different from the conventional jerk type fuel injection valve or its nozzle body in the high pressure portion (fuel passage 8).
Further, since the rail pressure from the common rail 7 is applied to the fuel storage chamber 9), there is a problem that the nozzle needle 4 and the intermediate 13 are worn more severely than before when the high pressure injection is performed.

A fuel injection valve of this type is disclosed in Japanese Patent Laid-Open No. Hei 9
-32681 and the like.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and provides a sliding portion wear reducing structure in a fuel injection valve capable of reducing a change with time of the fuel injection amount. The challenge is to provide.

Another object of the present invention is to provide a sliding part wear reducing structure in a fuel injection valve which can reduce wear of a nozzle needle, especially in a clearance hole in a nozzle body or the like.

Further, the present invention prevents the nozzle needle and the valve piston from falling in the radial direction from the axial direction,
An object of the present invention is to provide a sliding part wear reducing structure in a fuel injection valve capable of reducing wear of a nozzle needle and an intermediate.

[0014]

That is, the present invention provides a sleeve for connecting and guiding the valve piston and the nozzle needle at a contact portion or a joint portion of the valve piston and the nozzle needle, and by the sleeve, an axial direction of the nozzle needle. It focuses on suppressing the tilt of the nozzle to reduce wear and suppress changes in the injection performance over time.The nozzle body has injection holes that connect to the fuel passage and the axial direction in the nozzle body. A nozzle needle that lifts and seats to open and close the injection hole, and a valve piston that is movable integrally with the nozzle needle in the axial direction are provided, and fuel is ejected from the injection hole with the lift of the nozzle needle. A structure for reducing wear of sliding parts in a fuel injection valve that is capable of injecting, A slide in a fuel injection valve, characterized in that a sleeve is provided at a joint portion with a valve piston, and it is possible to prevent the lift of the nozzle needle and the nozzle needle and the valve piston due to the seat from falling in the axial direction. This is a structure for reducing the wear of moving parts.

An intermediate capable of adjusting the lift of the nozzle needle may be interposed between the nozzle needle and the valve piston.

A part of the valve piston can be a small diameter portion in the length direction.

As a control means for driving the valve piston and the nozzle needle in the axial direction, a back pressure control section capable of controlling the back pressure of the nozzle needle can be adopted.

In the structure for reducing wear of the sliding portion in the fuel injection valve according to the present invention, since the sleeve is provided at the contact portion between the valve piston and the nozzle needle, the valve piston and the nozzle needle having the sliding portion are provided by this sleeve. It is possible to fix in the radial direction to prevent the radial displacement, to prevent the sliding in the axial direction, to reduce the wear of the sliding portion, and to suppress the change in the injection performance over time.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Next, a fuel injection valve 20 having a sliding portion wear reducing structure according to an embodiment of the present invention will be described with reference to FIGS. However, FIG. 3 and FIG.
The same reference numerals are given to the same portions as, and the detailed description thereof will be omitted. 1 is a vertical cross-sectional view of the fuel injection valve 20, and FIG.
FIG. 3 is an enlarged cross-sectional view of a main part of a sliding portion wear reducing structure 21 portion of the fuel injection valve 20, wherein the sliding portion wear reducing structure 21 is
Joint 22 between nozzle needle 4 and valve piston 15
In the above, the intermediate 23 is interposed between both members, and the sleeve 24 is provided.

At the joint portion 22, the head portion 4B of the nozzle needle 4 is fitted in the skirt portion 24A located at the lowermost portion of the sleeve 24 with a sliding clearance left, and the top surface 4C of the nozzle needle 4 is formed by the intermediate surface. The bottom surface 23A of the wheel 23 and the inner step portion 24B of the sleeve 24 are in contact with each other. The top surface 23B of the intermediate 23 is
It is in contact with the arcuate bottom surface 15A of the valve piston 15.
The lowermost part of the valve piston 15 and the intermediate 23 are also fitted in the sleeve 24 leaving a sliding clearance. By selecting the thickness of the intermediate 23, the lift amount of the nozzle needle 4 can be adjusted.

The sleeve 24 can integrally guide the nozzle needle 4 and the valve piston 15 at the joint portion 22 and further the intermediate 23 in the axial direction, that is, in the lift and seat directions of the nozzle needle 4, and in the radial direction. It has a length that prevents the displacement and suppresses the inclination from the axial direction to the radial direction. The outer peripheral surface of the sleeve 24 itself does not slide in the spring chamber 12 and is spaced apart from the inner wall surface of the spring chamber 12 by a predetermined distance.

In particular, as shown in FIG. 1, the valve piston 15 has a small-diameter portion 25 at its upper portion in the lengthwise direction and has a radial deflection during movement in the axial direction (vertical direction). Can be absorbed in the small diameter portion 25.

In the fuel injection valve 20 and the sliding portion wear reducing structure 21 having such a structure, the valve needle 15 and the nozzle needle 4 are lifted and seated in the axial direction by the control of the back pressure control unit 5. Along with this, fuel is injected from the injection hole 10, but the sleeve 24 axially guides the lower portion of the valve piston 15, the intermediate 23 and the head portion 4B of the nozzle needle 4, and prevents the radial tilt from the axial direction. Since this is prevented, the wear of the nozzle needle 4 in the clearance hole 18 is reduced. Therefore, it is possible to suppress the change in the injection amount due to the wear of the nozzle needle 4, stabilize the fuel injection amount, and improve the reliability of the fuel injection valve 20. Further, it is possible to remove the coating for the wear prevention on the nozzle needle 4 portion, and it is possible to make this a rough tolerance in managing the clearance hole 18, so that it is possible to expect a cost reduction. Since the intermediate member 23 is arranged in the skirt portion 24A of the sleeve 24 that operates integrally with the intermediate member 23, this portion is less likely to be worn as compared with the conventional configuration (FIGS. 3 and 4). .

Further, since the valve piston 15 has the small diameter portion 25 formed in a part of its length, the bending of the valve piston 15 in the radial direction is absorbed by the bending of the small diameter portion 25. Therefore, it is possible to ensure the lift and the seat in the clearance hole 18 of the nozzle needle 4 along the axial direction.

[0025]

As described above, according to the present invention, since the sleeve is provided at the joint between the lower portion of the valve piston and the upper portion of the nozzle needle so that these can be guided, wear of the nozzle needle is reduced. However, it is possible to suppress changes in the performance of the fuel injection valve with time, thereby contributing to improved reliability and cost reduction.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a fuel injection valve 20 including a sliding portion wear reduction structure 21 according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of an essential part of a sliding portion wear reduction structure 21 portion of the same.

FIG. 3 is a vertical sectional view of a conventional fuel injection valve 1.

FIG. 4 is an enlarged cross-sectional view of the main part of the same.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Fuel injection valve (FIGS. 3 and 4) 2 Injector housing 3 Nozzle body 4 Nozzle needle 4A Pressure receiving part of nozzle needle 4 (FIGS. 2 and 4) 4B Head of nozzle needle 4 (FIG. 2) 4C Nozzle needle 4 Top surface (FIG. 2) 5 Back pressure control unit 6 Nozzle nut 7 Common rail (accumulator) 8 Fuel passage 9 Fuel reservoir chamber 10 Injection hole 11 Seat portion 12 Spring chamber (first sliding hole) 13 Intermediate (spring seat) ) 14 nozzle spring 15 valve piston 15A arcuate bottom surface of valve piston 15 (Fig. 2) 16 center hole of injector housing 2 valve body 18 of back pressure control unit 5 clearance hole (second sliding hole) 19A of intermediate 13 First sliding portion around (FIG. 4) 19B Second sliding portion around nozzle needle 4 Sliding part (FIG. 4) 20 Fuel injection valve (FIG. 1) 21 Sliding part wear reduction structure in fuel injection valve 20 (embodiment, FIG. 2) 22 Joint part 23 between nozzle needle 4 and valve piston 15 Intermediate 23A Bottom surface of intermediate 23 (FIG. 2) 23B Top surface of intermediate 23 (FIG. 2) 24 Sleeve 24A Skirt portion of sleeve 24 (FIG. 2) 24B Inner step portion of sleeve 24 (FIG. 2) 25 Valve piston 15 Small diameter part (Fig. 1)

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kazutaka Iioka             3-13-26, Yumichocho, Higashimatsuyama City, Saitama Prefecture             Expression company Bosch Automotive System             Higashi Matsuyama Factory F term (reference) 3G066 AA07 AB02 AD07 BA49 CC08T                       CC08U CC53 CE12 CE13                       CE31 CE34 CE35 CE37

Claims (3)

[Claims] 1. A nozzle body having an injection hole connected to a fuel passage, a nozzle needle that lifts and seats in the nozzle body in the axial direction to open and close the injection hole, and is integrally formed with the nozzle needle in the axial direction. And a sliding valve wear reducing structure in a fuel injection valve capable of injecting fuel from the injection hole with lift of the nozzle needle, the nozzle needle and the valve A sleeve is provided at a joint with a piston, and it is possible to prevent the nozzle needle and the valve piston associated with the lift of the nozzle needle and the seat from collapsing in the axial direction. Part wear reduction structure. 2. A sliding part in a fuel injection valve according to claim 1, wherein an intermediate capable of adjusting the lift of the nozzle needle is interposed between the nozzle needle and the valve piston. Wear reduction structure. 3. The sliding part wear reducing structure for a fuel injection valve according to claim 1, wherein a part of the valve piston has a small diameter portion in a length direction thereof.