JP2000179424A - Variable nozzle hole type fuel injection nozzle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a variable nozzle hole type fuel injection nozzle which can be adapted to an accumulation type fuel injection system adopting a common rail, prevent fuel leakage from a solenoid valve for a needle valve for lifting the needle valve, and improve processability of a precisely processed part. SOLUTION: A hydraulic command piston 19 and a solenoid valve 28 for a needle valve are arranged for controlling a needle valve 6. A rotary valve 26 is rotated by a drive shaft 25 for varying a sectional area of an injection hole 15. In such a variable injection hole type fuel injection nozzle, the hydraulic command piston 19 is operated for energizing the needle valve 6 in a closing direction, and the solenoid valve 28 is operated for controlling the back pressure of the hydraulic command piston 19. An armature of the solenoid valve 28 for the needle valve and the drive shaft 25 are made of an integrated member, that is, a valve shaft 33 of a two-way valve.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable injection hole type fuel injection nozzle, and more particularly to a fuel injection nozzle for supplying fuel to a diesel engine or other internal combustion engines in an atomized state. The present invention relates to a variable injection hole type fuel injection nozzle capable of making the injection hole area variable for each nozzle.

[0002]

2. Description of the Related Art A fuel injection nozzle for a fuel injection device having a pressure accumulation pipe (common rail) used for a diesel engine or other internal combustion engines, or a fuel for a jerk type fuel injection device for pumping fuel by the number of combustions of the engine. A fuel that improves engine performance by providing a variable injection hole variable mechanism of the rotary valve type in the injection nozzle, making the opening cross-sectional area (injection hole cross-sectional area) of the injection hole variable in the nozzle body, and realizing appropriate spray characteristics. Injection systems are being developed. For example, there are JP-A-9-280134 and JP-A-10-110661.

However, there has not yet been any of the above-mentioned common rail type fuel injection nozzles provided with an injection hole variable mechanism. That is, in the case of the conventional common rail fuel injection system, the fuel injection amount is determined mainly by only the two parameters of the injection pressure from the common rail and the injection period. There is a problem that can not be performed. Here, by making the injection hole area variable and increasing the control parameters, more detailed injection amount control can be performed. In addition, even when the injection amount is low, the injection holes can be narrowed, so that high-pressure fuel injection with a long injection period can be performed, and a spray pattern suitable for engine combustion can be formed. There is a problem that an appropriate configuration for providing an actuator for controlling the opening and closing of the fuel injection valve and an electromagnetic valve for driving the injection hole variable mechanism in the fuel injection nozzle portion has not been developed.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems and provides a variable injection hole type fuel injection nozzle applicable to a pressure accumulating type fuel injection system employing a common rail. That is the task.

Another object of the present invention is to provide a variable injection hole type fuel injection nozzle capable of preventing fuel leakage from a solenoid valve portion for a needle valve which performs lift control of a needle valve for opening and closing an injection hole. I do.

Further, the present invention improves the workability of the precision machining section by forming the back pressure chamber for controlling the lift of the needle valve and the seat portion of the solenoid valve for the needle valve as an integral part (housing body). It is an object to provide a variable injection hole type fuel injection nozzle that can be used.

[0007]

That is, the present invention provides a hydraulic command piston for controlling a needle valve and a solenoid valve for a needle valve, and further comprises an armature for the solenoid valve for a needle valve and a drive shaft for a rotary valve. It focuses on integrating into a single drive shaft as a valve body. The nozzle body has a nozzle hole having a predetermined nozzle hole cross-sectional area and a seat surface connected to the nozzle hole. A needle valve that is provided so as to be able to reciprocate and is capable of injecting fuel from the injection hole by lifting from the seat surface, and a rotary valve that can adjust a relative position of the injection hole,
An actuator such as a rotary solenoid for rotating the rotary valve; and a drive shaft for transmitting a driving force of the actuator to the rotary valve. The rotary valve is rotated by the actuator via the drive shaft. A variable injection hole type fuel injection nozzle capable of changing the injection hole cross-sectional area of the injection hole, the hydraulic command piston for urging the needle valve in a valve closing direction, and a back of the hydraulic command piston. A solenoid valve for a needle valve having, for example, a linear solenoid for controlling the pressure, and wherein the armature of the solenoid valve for the needle valve and the drive shaft are formed as an integral member. It is a hole-type fuel injection nozzle.

An orifice communicating with a back pressure chamber capable of applying fuel pressure to the hydraulic command piston, a leak hole through which the drive shaft passes, and a seat portion of the needle valve solenoid valve seated by the armature are simply provided. It can be formed in one housing body.

In the variable injection hole type fuel injection nozzle according to the present invention, the drive shaft of the rotary valve and the armature of the solenoid valve for the needle valve are integrated into a single drive shaft to transmit the operating force from the actuator to the rotary valve. To make the injection hole variable,
Since the needle valve is operated to be opened and closed by the solenoid valve for the needle valve, it is possible to have both the opening and closing function of the injection hole and the variable mechanism of the injection hole cross-sectional area, and the fuel injection system has a pressure accumulator such as a common rail. Even
The fuel injection nozzle itself can open and close the injection hole, and can vary the cross-sectional area of the injection hole to obtain spray characteristics suitable for engine combustion.

Further, if an orifice communicating with the inlet of the back pressure chamber of the hydraulic command piston, a leak hole through which the drive shaft passes, and a seat portion of the solenoid valve for a needle valve are formed in a single housing body, These precision processing parts can be easily made, and this housing body can be separated from the nozzle holder (nozzle housing) part and processed independently. Only the solenoid valve part for the needle valve is separated and prototyped. Therefore, the specification change of the fuel injection nozzle can be achieved in a short time.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A variable injection hole type fuel injection nozzle 1 according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a sectional view of a variable injection hole type fuel injection nozzle 1. The variable injection hole type fuel injection nozzle 1 includes a nozzle housing 2, a nozzle body 3, a housing body 4, and a solenoid housing attached to the nozzle housing 2. 5, a needle valve 6 that reciprocates in the nozzle body 3, and an injection hole variable mechanism 7.

A high-pressure fuel from a common rail 10 in which high-pressure fuel is accumulated from a fuel tank 8 by a fuel pump 9 can be supplied to the variable injection hole type fuel injection nozzle 1 from a fuel introduction unit 11. That is, the fuel introduction unit 11 for introducing the fuel to be pumped from the common rail 10 is connected to the housing body 4.
And a fuel passage 12 extending to the nozzle body 3.
Is formed, and pressure can be applied to the needle valve 6 in the fuel storage chamber 13.

FIG. 2 is an enlarged sectional view of a part II of FIG.
FIG. 3 is an enlarged cross-sectional view taken along line III-III of FIG. 2, in which the variable injection hole type fuel injection nozzle 1 is a hole nozzle type, in which a hole 14 is formed at a tip end of a nozzle body 3; A plurality of (for example, five) injection holes 15 are formed at equal angular intervals.

The needle valve 6 has a seat portion 16 which seats on a seat surface 17 which is connected to the injection hole 15 of the nozzle body 3.
And the injection hole 15 are shut off. The pressure receiving portion 18 of the needle valve 6 receives the fuel pressure in the fuel storage chamber 13 (FIG. 1). The needle valve 6 abuts a hydraulic command piston 19 at its upstream end, and the hydraulic command piston 19 causes the needle valve 6 to seat on the seat surface 17 of the nozzle body 3 by the urging force of a valve spring 20. When the needle valve 6 is lifted against the urging force of the valve spring 20, fuel can be injected from the injection hole 15.

The hydraulic command piston 19 forms a back pressure chamber 21 at the upper end thereof with the housing body 4, and the back pressure chamber 21 communicates with the fuel passage 12 through a small diameter orifice 22. It is. The upper end surface of the hydraulic command piston 19 is a pressure receiving surface 23, and the pressure receiving surface 23 has a pressure receiving area 23 S larger than the pressure receiving area 18 S of the pressure receiving portion 18 of the needle valve 6.

As shown in FIG. 1, the variable injection hole mechanism 7 has a rotary solenoid 24 (rotary valve actuator), a drive shaft 25 attached to the rotary solenoid 24, and a rotary valve 26. The rotary solenoid 24 is for rotating the rotary valve 26 to a predetermined angle via the drive shaft 25, and is provided with a rotation angle detector 27.

A solenoid valve 28 for a needle valve is provided in the solenoid housing 5 between the rotary solenoid 24 and the housing body 4 as a two-way valve. The needle valve solenoid valve 28 controls the back pressure of the hydraulic command piston 19 (the pressure in the back pressure chamber 21), and is a linear solenoid 29 (needle valve actuator).
An electromagnetic valve core 30, the drive shaft 25,
A valve spring 31.

The drive shaft 25 includes an actuator-side shaft portion 32 penetrating the rotary solenoid 24 and the linear solenoid 29, and a two-way valve shaft portion 33 (the armature of the needle valve solenoid valve 28).
And a drive shaft portion 34 extending to the rotary valve 26, so as to be integrally formed. The rotary valve 26 is integrally formed by a rotary connecting portion 35 extending long to the drive shaft portion 34 and a rotary valve portion 36 which is a conical main body.

The front end seat portion 37 of the two-way valve shaft portion 33 is seated on a seat portion 39 at an outlet portion of a leak hole 38 communicating with the back pressure chamber 21 of the housing body 4 so that the leak hole 38 can be opened and closed. . That is, when the two-way valve shaft portion 33 (drive shaft 25) is attracted toward the solenoid valve core 30 (upward in FIG. 1) and lifted against the urging force of the valve spring 31 by the excitation of the linear solenoid 29, the leakage occurs. The hole 38 is opened, and the fuel in the back pressure chamber 21 flows through the leak hole 38 and the leak passage 40.
The fuel is returned to the low-pressure portion (fuel tank 8) through the passage.
The cross-sectional area of the flow passage between the portion of the leak hole 38 and the drive shaft portion 34 of the drive shaft 25 is set to be larger than the cross-sectional area of the flow passage of the orifice 22, and the back pressure chamber is opened when the leak hole 38 is opened. The pressure in the fuel passage 21 is reduced through the leak hole 38 and the leak passage 40 and
From 2 the pressure receiving portion 18 of the needle valve 6 is maintained in a high pressure state.

As shown in FIG.
The rotary valve portion 36 is located below the needle valve 6 and can seat on the seat surface 17 inside the hole 14.
5, a seat circular arc portion 41 capable of closing the seat 5;
(In the example shown, five in each case) that can communicate with the injection hole 15.

When the needle valve 6 is seated or lifted, the rotary valve portion 36 is rotatable about its axis, and the seat circular arc portion 4 of the rotary valve portion 36 is rotated.
When the nozzle 1 faces the injection hole 15, the injection hole 15 is closed. When the variable groove 42 faces the injection hole 15, the fuel passage 12 and the injection hole 15 are moved through the variable groove 42 by the lift of the needle valve 6. Communication becomes possible.

As shown in FIG.
By rotating the nozzle 6 clockwise or counterclockwise, the relative position of the variable groove portion 42 of the rotary valve portion 36 with respect to the injection hole 15 in the nozzle body 3 is changed, and the opening degree of the injection hole 15 Area) can be changed.

In the housing body 4, the fuel introduction portion 11, the orifice 22, the leak hole 38, the leak passage 40, and the back pressure chamber 21 are formed, and the outer periphery of the hydraulic command piston 15 in the nozzle housing 2 is formed. A communicating return fuel outlet 43 is formed.

FIG. 4 is an enlarged sectional view of a main part of a portion where the drive shaft 25 and the rotary valve 26 are engaged.
Of the rotary connecting portion 35 of the rotary valve 26 and the rotary connecting concave portion 45 formed at the distal end of the rotary connecting portion 35 of the rotary valve 26 to form axial play and rotational integration. And the rotation connecting portion 35.
The coil spring 47 is disposed between the tip of the hydraulic command piston 19 and the spring seat surface 46 of the hydraulic command piston 19. Thus, the rotary valve 26 is connected to the drive shaft 25.
More specifically, the rotary valve portion 36 of the rotary valve 26 can seat the hole 14 or the seat surface 17 of the nozzle body 3 with a predetermined pressing force.

In the variable injection hole type fuel injection nozzle 1 or the injection hole variable mechanism 7 having such a configuration, the drive shaft 25 is rotated by a predetermined angle by the excitation of the rotary solenoid 24. Further, the two-way valve shaft portion 33 is lifted from the seat portion 39 of the leak hole 38 by excitation of the linear solenoid 29, and the pressure in the back pressure chamber 21 is reduced through the leak hole 38 and the leak passage 40 to the low pressure side (fuel tank). 8) and lift the needle valve 6. The demagnetization of the linear solenoid 29 causes the two-way valve shaft portion 33 to seat in the seat portion 39 of the leak hole 38, the fuel pressure from the orifice 22 increases the pressure in the back pressure chamber 21, and causes the needle valve 6 to seat the seat surface 17. To terminate the fuel injection.

Thus, the drive shaft 25 for rotating the rotary valve 26, particularly the two-way valve shaft portion 33, is also used as an armature of the needle valve solenoid valve 28 for operating the needle valve 6. Therefore, both the rotary valve 26 and the needle valve 6 can be driven, and spray characteristics suitable for engine combustion can be arbitrarily obtained. In particular, common rail 10
The injection hole variable mechanism 7 can be combined with the accumulator type fuel injection device adopting the above.

Further, since the housing body 4 is divided from the nozzle housing 2 and the like into a single separate member, precision processing of the orifice 22, the leak hole 38, and the sheet portion 39 at the outlet of the leak hole 38 is required. Can be easily made.

As described above, the drive shaft 25 has at least the actuator side shaft portion 3.
2 and the two-way valve shaft portion 33, which are integrally formed, so that the sealing performance of the fuel in the seat portion 39 can be improved, and the return fuel amount can be reduced.

Since the coil spring 47 is interposed between the hydraulic command piston 19 and the rotary valve 26, the drive shaft 25 and the rotary valve 26 penetrating through the hydraulic command piston 19 are substantially displaced in the axial direction. It can be integrated, and the instability in the rotary valve 26, particularly in the hole 14 portion of the rotary valve portion 36 can be eliminated.

Further, since the coil spring 47 is not in the hole 14 of the nozzle body 3 but in the upstream portion of the tip of the rotation connecting portion 35 distant from the hole 14, the hole 1
There is no risk of turbulence that may affect the fuel flow in the space from the tip of the needle valve 4 to the injection hole 11.

[0031]

As described above, according to the present invention, the back pressure of the hydraulic command piston for urging the needle valve in the valve closing direction is controlled, and the armature of the solenoid valve for the needle valve and the drive shaft are integrated. As a result, it is possible to equip the accumulator type fuel injection device with the injection hole variable mechanism, and it is possible to improve the ease of machining the precision machining part.

[Brief description of the drawings]

FIG. 1 is a sectional view of a variable injection hole type fuel injection nozzle 1 according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a part II of FIG.

FIG. 3 is an enlarged sectional view taken along line III-III of FIG. 2;

FIG. 4 is an enlarged sectional view of a main part of a portion where the drive shaft 25 and the rotary valve 26 are engaged.

[Explanation of symbols]

Reference Signs List 1 variable injection hole type fuel injection nozzle (embodiment, FIG. 1) 2 nozzle housing 3 nozzle body 4 housing body 5 solenoid housing 6 needle valve 7 injection hole variable mechanism 8 fuel tank 9 fuel pump 10 common rail 11 fuel introduction unit 12 fuel Passage 13 Fuel reservoir 14 Hole 15 Injection hole 16 Seat portion of needle valve 6 17 Seat surface of nozzle body 3 18 Pressure receiving portion of needle valve 6 18S Pressure receiving area of pressure receiving portion 18 (18S <23S) 19 Hydraulic command piston 20 Valve spring Reference Signs List 21 back pressure chamber 22 orifice 23 pressure receiving surface of hydraulic command piston 19 23S pressure receiving area of pressure receiving surface 23 24 rotary solenoid (actuator for rotary valve) 25 drive shaft 26 rotary valve 27 rotation angle detector 28 needle Solenoid valve 29 Linear solenoid (actuator for needle valve) 30 Electromagnetic valve core 31 Valve spring 32 Actuator side shaft of drive shaft 25 33 Two-way valve shaft portion of drive shaft 25 (armature of solenoid valve 28 for needle valve) 34 Drive Drive shaft part of shaft 25 35 Rotating connection part of rotary valve 26 Rotary valve part of rotary valve 37 Tip seat part of two-way valve shaft part 33 38 Leak hole 39 Seat part at outlet part of leak hole 38 Leak 40 Passage 41 Seat arc portion of rotary valve portion 42 Variable groove portion of rotary valve portion 43 Return fuel outlet 44 Rotation connection projection of drive shaft portion 45 Rotation connection of rotation connection portion 35 Part 46 spring seat surface 47 a coil spring

Claims (2)

[Claims] An injection hole having a predetermined injection hole cross-sectional area and a nozzle body having a sheet surface connected to the injection hole; a nozzle body provided reciprocally in the nozzle body, and lifted from the sheet surface. A needle valve capable of injecting fuel from the injection hole, a rotary valve capable of adjusting a relative position with respect to the injection hole, an actuator for rotating the rotary valve, and transmitting a driving force of the actuator to the rotary valve A variable injection hole type fuel injection nozzle capable of changing the injection hole cross-sectional area of the injection hole by rotating the rotary valve by the actuator via the drive shaft. A hydraulic command piston for urging the needle valve in the valve closing direction; A solenoid valve for a needle valve for controlling the back pressure of the needle valve, and the armature of the solenoid valve for the needle valve and the drive shaft are formed as an integral member. Injection nozzle. 2. An orifice communicating with a back pressure chamber capable of applying fuel pressure to the hydraulic command piston; a leak hole through which the drive shaft passes; and a seat on which the armature of the solenoid valve for a needle valve seats. 2. The variable injection hole type fuel injection nozzle according to claim 1, wherein the fuel injection nozzle is formed in a single housing body.