JP2000186646A - Variable nozzle type fuel injection nozzle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a variable nozzle type fuel injection nozzle to have a control valve for a needle valve to have a nozzle variable mechanism and improve the degree of freedom of spray and be applicable for a pressure storage type fuel injection device having a common rail, and perform control of a needle valve, and control opening and closing of a leak hole communicated with a back pressure chamber and be constituted in a compact manner. SOLUTION: This fuel injection nozzle is provided with a hydraulic command piston 18 to control a needle valve 5 and a control valve 28 for a needle valve. It is noticed that the drive shaft 24 of a rotary valve 25 leads to a rotary valve 25 through the control valve 28 for a needle valve. The control valve 28 for a needle valve is provided to control the back pressure of the hydraulic command piston 18 to energize the needle valve 5 in a closing direction, and a drive shaft 24 is extended to the rotary valve 25 through the control valve 28 for a needle valve, the hydraulic command piston 18, and its back pressure chamber 20.

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 injection.

[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, JP-A-8-93601, JP-A-9-280134 or JP-A-10-1106
No. 61 etc.

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 which has an injection hole variable mechanism and can increase the degree of freedom of spraying.

Further, the present invention comprises a needle valve control valve for performing a lift control of the needle valve, which is a two-way valve,
An object of the present invention is to provide a variable injection hole type fuel injection nozzle which realizes a compact configuration by controlling the opening and closing of a leak hole communicating with the back pressure chamber.

[0007]

That is, the present invention provides a hydraulic command piston for controlling a needle valve and a control valve for a needle valve. Further, a drive shaft of the rotary valve is connected to a rotary valve via a control valve for a needle valve. Focus on getting to
A nozzle body having an injection hole having a predetermined injection hole cross-sectional area and a sheet surface connected to the injection hole; a nozzle body provided reciprocally in the nozzle body; and a fuel from the injection hole by being lifted from the sheet surface. A needle valve capable of injecting, a rotary valve capable of adjusting a relative position of the injection hole, an actuator for rotating the rotary valve, a drive shaft for transmitting a driving force of the actuator to the rotary valve, A variable injection hole type fuel injection nozzle having a rotary shaft that is rotated by the actuator via the drive shaft to change the injection hole cross-sectional area of the injection hole, wherein the needle valve Command piston that urges the hydraulic command piston in the valve closing direction, and controls the back pressure of this hydraulic command piston. A control valve for a needle valve, and wherein the drive shaft extends to the rotary valve via the control valve for the needle valve, a back pressure chamber of the hydraulic command piston, and the hydraulic command piston. This is a variable injection hole type fuel injection nozzle.

In the back pressure chamber of the hydraulic command piston,
Fuel is supplied from the pressure source through the orifice, and the fuel in the back pressure chamber can be discharged to the low pressure side through the leak hole along the drive shaft, through the seat portion of the needle valve control valve. There can be.

[0009] The actuator may be a rotary solenoid and a rotation angle detector capable of detecting the rotation angle of the rotary solenoid.

The above-mentioned actuator can be used as a stepping motor.

The control valve for a needle valve may be a solenoid valve for a needle valve, and the drive shaft may extend to the rotary valve via an electromagnetic core and an armature of the solenoid valve for a needle valve. .

The control valve for a needle valve may include a piezoelectric element, and the drive shaft may extend to the rotary valve via the piezoelectric element.

In the variable injection hole type fuel injection nozzle according to the present invention, a rotary valve and a drive shaft for driving the rotary valve are adopted as a variable injection hole mechanism, and a hydraulic command piston and a needle valve control valve are provided to provide a needle valve. And the drive shaft extends from the actuator to the rotary valve through the needle valve control valve, the back pressure chamber of the hydraulic command piston, and the hydraulic command piston. In addition, it is possible to change both the opening degree and the opening degree, and it is possible to obtain a compact configuration as a whole.

Therefore, even a fuel injection system having a common rail or the like can have an injection hole variable function, and can select a spray characteristic with a high degree of freedom, and can also perform pilot injection and multi-stage injection. Engine performance can be improved. Of course, the present invention is applicable not only to the common rail type fuel injection device but also to the jerk type fuel injection device.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A variable injection hole type fuel injection nozzle 1 according to a first 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.
It has a nozzle housing 2, a nozzle body 3 and a solenoid housing 4 attached to the nozzle housing 2, a needle valve 5 that reciprocates in the nozzle body 3, and an injection hole variable mechanism 6.

A high-pressure fuel from a common rail 9 in which high-pressure fuel is accumulated from a fuel tank 7 by a fuel pump 8 can be supplied to the variable injection hole type fuel injection nozzle 1 from a fuel introduction unit 10. That is, a fuel introduction portion 10 for introducing the fuel to be pumped from the common rail 9 is formed in the housing body 4, a fuel passage 11 is formed to the nozzle body 3, and pressure can be applied to the needle valve 5 in the fuel accumulation chamber 12. .

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

The needle valve 5 has a seat portion 15 that seats on a seat surface 16 connected to the injection hole 14 of the nozzle body 3, thereby blocking the fuel passage 11 from the fuel introduction portion 7 and the injection hole 14. . Fuel reservoir 12 (FIG. 1)
The pressure receiving portion 17 of the needle valve 5 receives the fuel pressure. The needle valve 5 abuts a hydraulic command piston 18 at an upstream end thereof, and the hydraulic command piston 18 seats the needle valve 5 on the seat surface 16 of the nozzle body 3 by the urging force of a valve spring 19. When the needle valve 5 is lifted against the urging force of the valve spring 19, fuel can be injected from the injection hole 14.

The hydraulic command piston 18 forms a back pressure chamber 20 at the upper end with the inner wall surface of the nozzle housing 2, and the back pressure chamber 20 is formed between the back pressure chamber 20 and the fuel passage 11 by an orifice 21 having a small diameter. Is in communication. The upper end surface of the hydraulic command piston 18 is a pressure receiving surface 22, and a pressure receiving area 22 S of the pressure receiving surface 22 is larger than a pressure receiving area 17 S of the pressure receiving portion 17 of the needle valve 5.

As shown in FIG. 1, the injection hole variable mechanism 6 includes a rotary solenoid 23 (rotary valve actuator) and a drive shaft 24 attached to the rotary solenoid 23 and extending to the tip of the needle valve 5.
And a rotary valve 25 facing the injection hole 14 in the hole 13 of the nozzle body 3, and a control circuit 26. The rotary solenoid 23 is connected to the drive shaft 2
A rotary angle detector 27 is provided for rotating the rotary valve 25 to a predetermined angle via the control unit 4. The control circuit 26 controls the drive of the rotary angle detector 27.

The solenoid housing 4 between the rotary solenoid 23 and the nozzle housing 2 is provided with a needle valve solenoid valve 28 (needle valve control valve) as a two-way valve. The needle valve solenoid valve 28 controls the back pressure of the hydraulic command piston 18 (the pressure in the back pressure chamber 20), and includes a linear solenoid 29 (needle valve actuator), a solenoid valve core 30, and a two-way valve. Valve shaft 31 (armature) and valve spring 32
And a control circuit 26 in the injection hole variable mechanism 6.

The tip seat portion 33 of the two-way valve shaft 31 seats on the seat portion 35 at the outlet of the leak hole 34 communicating with the back pressure chamber 20 of the nozzle housing 2 so that the leak hole 34 can be opened and closed. That is, the linear solenoid 2 based on the control signal from the control circuit 26
9 excites the two-way valve shaft 31 against the biasing force of the valve spring 32 toward the solenoid valve core 30 (FIG. 1).
When the suction is lifted (middle upward), the leak hole 34 is opened, and the fuel in the back pressure chamber 20 is returned to the low pressure portion (fuel tank 7) through the leak hole 34 and the leak passage 36. The drive shaft 24 at the leak hole 34
Is larger than the cross-sectional area of the orifice 21, and when the leak hole 34 is opened, the pressure of the back pressure chamber 20 is reduced through the leak hole 34 and the leak passage 36. And the needle valve 5 from the fuel passage 11
The pressure receiving section 17 is maintained in a high pressure state.

The drive shaft 2 of the injection hole variable mechanism 6
4 passes (penetrates) through the rotary solenoid 23, the solenoid valve core 30 of the linear solenoid 29, the two-way valve shaft 31, the leak hole 34, the back pressure chamber 20, and the hydraulic command piston 18 from the top of the nozzle housing 2.
And it is inserted into the through shaft hole 37 of the needle valve 5 and reaches the rotary valve 25 below it.

As shown in FIG.
The drive shaft 24 and the rotary valve 25 are connected by a rotation connection concave portion 38 at the tip end thereof and a rotation connection projection 39 of the rotary valve 25, and the drive shaft 24 and the rotary valve 25 are connected to each other. The drive shaft 24 is connected to the rotary valve 25 so as to be movable in the axial direction (with play) and to transmit the rotational movement of the drive shaft 24 to the rotary valve 25. A connection portion between the drive shaft 24 and the rotary valve 25, specifically, a coil spring 42 is provided between a tip end face 40 of the drive shaft 24 and an upper end face 41 of the rotary valve 25.
(Elastic member), the rotary valve 2
5 is urged in the axial direction of the drive shaft 24, specifically, in the direction of the seat surface 16 of the nozzle body 3, and the rotary valve 25 is pressed against the injection hole 14 so that its relative position can be fixed. Instability due to play between the moving connecting concave portion 38 and the rotating connecting convex portion 39 is avoided.

The rotary valve 25 is located below the needle valve 5 and can seat on the seat surface 16 in the hole 13, has a substantially conical shape tapered downstream, and can close the injection hole 14. And a variable groove portion 44 between the seat circular arc portion 43 and the communication hole 41.
(In the illustrated example, five each).

When the needle valve 5 is seated or lifted, the rotary valve 25 can rotate around its axis independently of the needle valve 5.
5 is closed when the seat circular arc portion 43 is opposed to the injection hole 14, and when the variable groove portion 44 faces the injection hole 14, the fuel passage 11 and the injection hole 14 are changed by the lift of the needle valve 5. Communication becomes possible via the groove 44.

As shown in FIG.
By rotating the nozzle clockwise or counterclockwise, the relative position of the variable groove portion 44 of the rotary valve 25 with respect to the injection hole 14 in the hole 13 of the nozzle body 3 is changed, and the opening degree (opening) of the injection hole 14 is changed. (Cross-sectional area) is variable.

In the variable injection hole type fuel injection nozzle 1 and the injection hole variable mechanism 6 having such a configuration, the fuel from the fuel introduction section 7 and the fuel passage 11 acts on the pressure receiving section 17 of the needle valve 5 in the fuel accumulation chamber 12. The needle valve 5 is urged in the lift direction, and the pressure receiving surface 22 of the hydraulic command piston 18 is pressed downward in the back pressure chamber 20 through the orifice 21 on the upstream side in the figure, thereby urging the needle valve 5 in the seat direction. I do. In the demagnetized state of the linear solenoid 29, the front seat portion 33 of the two-way valve shaft 31 seats on the seat portion 35 and closes the leak hole 34 by the urging force of the valve spring 32. 20 is high pressure, and due to the difference between the pressure receiving area of the pressure receiving surface 22 and the pressure receiving area of the pressure receiving portion 17 (the former is larger),
The needle valve 5 remains seated on the seat surface 16 of the nozzle body 3, and the injection from the injection hole 14 is not performed.

When the drive shaft 24 is rotated by a predetermined angle by the rotary solenoid 23 in the injection stop state, the relative positions of the variable grooves 44 and the seat circular arc portion 43 of the rotary valve 25 and the injection holes 14 are adjusted. The injection hole cross-sectional area of the injection hole 14 can be made variable.

The excitation of the linear solenoid 29 causes the two-way valve shaft 31 to leak through the leak hole 34 (seat portion 35).
From the fuel introduction section 7 to the orifice 21
The fuel that has reached the back pressure chamber 20 via the leak hole 34 and the leak passage 36 is leaked to the low pressure side through the leak hole 34 and the leak passage 36. 3 is lifted from the seat surface 16 and fuel injection from the injection holes 14 is performed. Note that even in this fuel injection state, the rotary solenoid 23
By operating the drive shaft 24, the rotary valve 25 is rotated with respect to the injection hole 14 to change the injection hole cross-sectional area, and the spray characteristics can be adjusted even during injection.

When the fuel is injected when the needle valve 5 is lifted and when the rotary valve 25 is turned, the driving force of the drive shaft 24 is applied to the turning connection recess 3.
The rotary valve 25 received at the portion 8 and the connecting projection 39 for rotation is arranged in a state of being protruded between the distal end surface 40 of the drive shaft 24 and the hole 13 or the seat surface 16 of the nozzle body 3 by the coil spring 42. Therefore, the rotary valve 25 is stably positioned in the hole 13 in a fixed state, and the relative position between the rotary valve 25 and the injection hole 14 is stably maintained. Characteristics can be stabilized.

In the variable injection hole type fuel injection nozzle 1, the rotary valve 25 is provided separately from the drive shaft 24, but these may be integrated. That is, FIG. 4 shows an injection hole variable mechanism 45 as a modification.
FIG. 4 is an enlarged sectional view showing a main part of the nozzle hole variable mechanism 45;
The variable injection hole type fuel injection nozzle 1 incorporates a rotary valve 46 in which the drive shaft 24 and the rotary valve 25 are integrated.

The tip cone 47 of the rotary valve 46 seats on the seat surface 16 of the nozzle body 3, and the variable groove 48 formed in the tip cone 47 faces the injection hole 14, and the relative positional relationship with the injection hole 14. Thus, the aperture can be made variable.

Also in the injection hole variable mechanism 45 having such a configuration, the cross-sectional area (opening) of the injection hole 14 can be arbitrarily changed, and the drive shaft 24 and the rotary valve can be arranged as shown in FIG. There is no need to provide the coil spring 42 between the holes 25 and the fuel flow in the hole 13 can be made uniform. Further, the number of parts is small, and the degree of opening of the injection hole 14 can be variably controlled more precisely.

Thus, the variable injection hole type fuel injection nozzle 1 is provided with the injection hole variable mechanism 6 together with the solenoid valve 29 for the needle valve, and both of them are driven and controlled by the control circuit 26, whereby the lift control of the needle valve 5 is controlled. , And the opening degree of the injection hole 14 can be controlled together,
The fuel injection device having the common rail 9 and the like can also exhibit the injection hole variable function.

FIG. 5 is a sectional view of a variable injection hole type fuel injection nozzle 50 according to a second embodiment of the present invention. A stepping motor 52 is used instead of the rotary solenoid 23, and a piezoelectric element 53 is used as a needle valve control valve instead of the needle valve solenoid valve 28 (FIG. 1). Therefore, the linear solenoid 29 (needle valve actuator) of the needle valve solenoid valve 28 in the variable injection hole type fuel injection nozzle 1 according to the first embodiment is unnecessary.

That is, the front end sheet portion 5 of the piezoelectric element 53
4 is seated on the sheet portion 35 of the leak hole 34 and the leak hole 3
4 can be opened and closed.

In the variable injection hole type fuel injection nozzle 50 and the injection hole variable mechanism 51 having such a configuration, when a voltage is applied to the piezoelectric element 53 by the control signal of the control circuit 26, the piezoelectric element 53 contracts slightly, and Open the hole 34,
As described above, the needle valve 5 can be lifted. Conversely, when the application of the voltage is stopped, the piezoelectric element 53 returns to its original state, seats on the seat portion 35, closes the leak hole 34, and stops the lift of the needle valve 5. Therefore, by controlling the voltage application to the piezoelectric element 53,
Pilot injection and multi-stage injection are also possible.

The operation of the nozzle hole variable mechanism 51 itself is substantially the same as that of the previously described nozzle hole variable mechanism 6. That is, like the rotary solenoid 23 of the injection hole variable mechanism 6 (FIG. 1) in the first embodiment, the stepping motor 5
2, the rotation of the drive shaft 24 and the control of the rotary valve 25 can be performed.

In the variable injection hole type fuel injection nozzle 50 according to the second embodiment, the variable injection hole according to the first embodiment is also used for rotating the drive shaft 24, that is, for driving the rotary valve 25. Similarly to the type fuel injection nozzle 1, using the rotary solenoid 23,
It can be combined with the two-way valve using the piezoelectric element 53 described above.

[0041]

As described above, according to the present invention, the variable injection hole mechanism and the control valve for the needle valve are combined, and the drive shaft of the variable injection hole mechanism is moved from the upper part of the variable injection hole type fuel injection nozzle to the rotary valve. Since it extends to the lower part, it can have both the function of opening and closing the injection hole and the function of changing the cross-sectional area of the injection hole, and can be applied to a fuel injection system having a common rail.

[Brief description of the drawings]

FIG. 1 is a sectional view of a variable injection hole type fuel injection nozzle 1 according to a first 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 showing a main part of an injection hole variable mechanism 45 as a modification.

FIG. 5 is a sectional view of a variable injection hole type fuel injection nozzle 50 according to a second embodiment of the present invention.

[Explanation of symbols]

Reference Signs List 1 variable injection hole type fuel injection nozzle (first embodiment, FIG. 1) 2 nozzle housing 3 nozzle body 4 solenoid housing 5 needle valve 6 injection hole variable mechanism of variable injection hole type fuel injection nozzle 1 7 fuel tank 8 fuel Pump 9 Common rail 10 Fuel introduction part 11 Fuel passage 12 Fuel reservoir 13 Hole 14 Injection hole 15 Seat part of needle valve 5 16 Seat surface of nozzle body 3 17 Pressure receiving part of needle valve 5 17S Pressure receiving area of pressure receiving part 17 (17S < 22S) 18 hydraulic command piston 19 valve spring 20 back pressure chamber 21 orifice 22 pressure receiving surface of hydraulic command piston 22 22S pressure receiving area of pressure receiving surface 22 23 rotary solenoid (actuator for rotary valve) 24 drive shaft 25 rotary valve 26 control circuit 27 times Angle detector 28 Solenoid valve for needle valve (control valve for needle valve, two-way valve) 29 Linear solenoid (needle valve actuator) 30 Solenoid valve core 31 Two-way valve valve shaft (armature) 32 Valve spring 33 Two-way valve valve Tip seat part of shaft 31 Leak hole 35 Seat part at outlet part of leak hole 34 Leak passage 37 Penetrating shaft hole of needle valve 5 38 Rotating connection concave part at tip of drive shaft 24 39 Rotation connection of rotary valve 25 Convex portion 40 Tip surface of drive shaft 24 41 Upper end surface of rotary valve 25 42 Coil spring (elastic member) 43 Seat arc portion of rotary valve 25 44 Variable groove portion of rotary valve 25 45 Injection hole variable mechanism (modification, FIG. 4) ) 46 Rotary valve 47 Tip conical part of rotary valve 46 48 Variable groove part of tip conical part 47 50 Variable injection hole type fuel injection nozzle (second embodiment,
5) 51 Injection hole variable mechanism of variable injection hole type fuel injection nozzle 50 52 Stepping motor 53 Piezoelectric element (control valve for needle valve, two-way valve) 54 Front end sheet portion of piezoelectric element 53

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) F02M 61/20 F02M 61/20 P (72) Inventor Takashi Kobayashi 3- 13-26 Yayumicho, Higashimatsuyama-shi, Saitama 3G066 AA07 AB02 AC09 AD12 BA03 BA12 BA67 CC05U CC06T CC08T CC14 CC23 CC26 CC48 CC64T CC66 CC67 CC68U CC70 CD25 CD26 CE22 CE27 DA09 DA16

Claims (6)

[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 control valve for a needle valve that controls the back pressure of the needle valve, and the drive shaft extends to the rotary valve via the control valve for the needle valve, the back pressure chamber of the hydraulic command piston, and the hydraulic command piston. A variable injection hole type fuel injection nozzle extending. 2. A back pressure chamber of the hydraulic command piston is supplied with fuel from a pressure source through an orifice, and the fuel in the back pressure chamber passes through a leak hole along the drive shaft to the needle. 2. The variable injection hole type fuel injection nozzle according to claim 1, wherein the fuel can be discharged to a low pressure side through a seat portion of the valve control valve. 3. The variable injection hole fuel injection according to claim 1, wherein said actuator is a rotary solenoid and a rotation angle detector capable of detecting a rotation angle of said rotary solenoid is provided. nozzle. 4. The variable injection hole type fuel injection nozzle according to claim 1, wherein said actuator is a stepping motor. 5. The needle valve control valve is a needle valve solenoid valve, and the drive shaft extends to the rotary valve via an electromagnetic core and an armature of the needle valve solenoid valve. The variable injection hole type fuel injection nozzle according to claim 1, wherein: 6. The control valve for a needle valve according to claim 1, further comprising a piezoelectric element, wherein the drive shaft extends to the rotary valve via the piezoelectric element.
The variable injection hole type fuel injection nozzle as described in the above.