JPH08338341A - Nozzle hole switching type fuel injection nozzle - Google Patents

Abstract

PURPOSE: To switch-over a nozzle hole without changing its injection direction in the circumferential direction by providing a rotary valve capable of being slidably rotated in the inside of the hole, and concurrently providing a band shaped shielding part provided with an inclination with respect to a valve stem. CONSTITUTION: A plurality of nozzle holes 35 are disposed over the wall of a tip end part 32 enclosing a hole 34 at specified intervals in its circumferential direction while being, furthermore disposed over different circumferences. A rotary valve 7 is provided with a band shaped shielding part 72 having an inclination with respect to its axial line, and a plurality of fuel passages 73 opened in the vertical direction are disposed at specified intervals in a disc shaped member provided integrally with a stem part 71 at its center. Positioning in the stem axial direction is made by letting the lower end of the stem part 71 be brought into contact with the bottom of the hole 34, under the aforesaid condition, large nozzle holes 35a are covered by the disc shaped member, on the other hand, small nozzle holes 35b are not covered so as to be communicated with the inside of the hole 34. Therefore, fuel can thereby be injected out of the different nozzle holes in the nozzle axial direction, and a reduction in NOx and improvement in fuel consumption can thereby be materialized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection nozzle, and more particularly to an injection hole switching type fuel injection nozzle.

[0002]

2. Description of the Related Art In a diesel engine or the like, a fuel injection nozzle is generally used as a means for supplying fuel in an atomized state.
As disclosed in Japanese Patent Application Laid-Open No. 200063, a needle valve is accommodated in a nozzle body so as to be slidable in an axial direction, and a tapered pressure receiving surface is formed on a tip end side of the needle valve to apply a fuel pressure. As a result, the valve is opened, and the structure is such that injection is performed from the injection hole formed at the tip of the nozzle body. However, in this structure, the fuel injection pressure, injection amount, injection speed, etc. are normally determined by the oil pump, and the number of injection holes is fixed, and the total area of injection holes cannot be increased or decreased. . As a result, the fuel injection pressure becomes low at low engine speeds, and the injection time becomes short at low engine load, which makes it impossible to maintain a good combustion state, promoting combustion, and improving output and fuel efficiency. However, the problem of reduction of combustion noise and NOx could not be dealt with.

As a countermeasure against this, in Japanese Patent Laid-Open No. 4-76266, a plurality of injection holes communicating with the internal holes are formed at the tip of the nozzle body at intervals in the circumferential direction, and the rotary valve is rotated in the holes. It has been proposed that the rotary valve is freely attached and the opening of the injection hole is adjusted by rotation of the rotary valve. In this prior art, it is possible to set a desired injection hole area by controlling the rotation of the rotary valve. However, in the above-mentioned prior art, since the injection holes are switched in the circumferential direction, when the injection holes are switched, the injection direction changes in the circumferential direction as shown in FIGS. Therefore, inconvenience may occur depending on the mounting position of the fuel injection nozzle and the shape of the combustion chamber. For example, when the fuel injection nozzle is obliquely inserted into the hole-shaped combustion chamber, in the prior art, the injection direction in the circumferential direction changes, so the spray balance may be lost.

[0004]

SUMMARY OF THE INVENTION The present invention was made by research to solve the above problems, and its purpose is to change the injection direction in the circumferential direction with a simple structure. An object of the present invention is to provide a fuel injection nozzle of the injection hole switching type, which can switch the injection holes without having to do so, and which meets the requirements such as the injection nozzle mounting position and the shape of the combustion chamber.

In order to achieve the above object, the present invention forms a hole for introducing pressurized fuel at the tip of the nozzle body,
A needle valve that opens and closes at a predetermined fuel pressure is arranged on the inlet side of this hole, and a plurality of injection holes having different diameters are arranged at intervals on the peripheral wall of the hole, while a rotary rotary that can slide and rotate in the hole. A valve is arranged, and the rotary valve has a band-shaped shielding portion having an inclination angle with respect to the valve axis. The strip-shaped shield may be made of a disc-shaped member having a fuel passage in the vertical direction. Alternatively, it may be composed of a spiral member.

[0006]

In the present invention, since a plurality of injection holes having different diameters are arranged on the peripheral wall of the hole, and the rotary valve has a band-shaped shield portion that has an angle with respect to the valve axis on the outer surface, the rotary valve is If rotation is controlled by the actuator in the intake stroke and / or the exhaust stroke of the engine,
Since the position of the shielding part moves by the function y = sinx depending on the rotation angle, the inside of the hole and the injection hole are selectively communicated with each other, fuel is injected only from the selected injection hole, and the other injection holes are strip-shaped. It is not ejected because it is shielded by the shielding part of. Therefore, the size of the injection hole is switched in the direction of the rotation axis, and the injection hole area is changed.

[0007]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 to 5 show a first embodiment of the present invention. In FIG. 1, 1 is a nozzle holder body, 2 is a drive head that is oil-tightly fitted and fixed to the upper end of the nozzle holder body 1 through an O-ring, and 3 is connected to the lower end of the nozzle holder body 1. , A nozzle body 4 connected to the nozzle holder body 1 by a retaining nut 5, and needle valves (nozzle needles) 4 inserted in the nozzle body 3. The nozzle holder body 1 has a first hole 100a through a third hole 100a whose diameters gradually increase from the lower end to the upper end of the shaft center.
A hole 100c is provided, and the first hole 100a to the second hole 100a are formed.
A push rod 101 is slidably inserted in a region reaching the hole 100b. Also, from the third hole 100c to the second
An adjusting screw 102 screwed into the female screw of the third hole 100c is fitted in the region reaching the hole 100b,
A nozzle spring 103 is interposed between the adjusting screw 102 and the push rod 101.

The nozzle body 3 has a step portion 30 fitted in the bottom of the retaining nut 5 at the middle portion in the longitudinal direction of the outer surface, and a main portion 31 extending below the step portion 30 through the retaining nut 5. Is provided, and the main portion 31 has a tip portion 32 for a nozzle hole formed through a tapered portion. on the other hand,
On the axis of the nozzle body 3, from the upper end to the lower end,
A guide hole 300 concentric with the first hole 100a of the nozzle holder body 1 and an oil sump 301 having a diameter larger than that of the guide hole 300 are formed, and further below the oil sump 301, relative to the guide hole 300. A small diameter guide hole 30
2, a conical seat surface 303 is formed at the lower end of the guide hole 302 as shown in FIG. 2, and a bottomed hole 34 through which the pressurized fuel is guided subsequent to the seat surface 303. Are formed. The hole 34 has a cylindrical shape as shown in FIG. 2, and the lower end is closed by an end wall. A pressurized fuel port 104 connected to an inlet connector is provided at one side of the nozzle holder body 1, and the pressurized fuel port 104 has passage holes 105 and 305 formed in the nozzle holder body 1 and the nozzle body 3. Through the oil sump 30
1 to communicate with the pressurized fuel.

The needle valve 4 has an engaging portion 41 for the push rod 101 at the upper end, a guide portion 40 slidably contacting the guide hole 300 on the outer periphery, and an oil sump 301 at the end of the guide 40. A pressure receiving portion 42 for receiving the fuel pressure in the inside is provided.
As described above, the thin shaft portion 43 for forming the cylindrical fuel passage A with the guide hole 302 is provided, and the lower end of the thin shaft portion 43 has a conical shape that comes in contact with and separates from the seat surface 303. A seat surface 44 is formed.

As shown in FIGS. 2 and 3, a plurality of injection holes 35 communicating with the hole 34 are formed on the wall of the tip portion 32 surrounding the hole 34 at predetermined intervals in the circumferential direction and are different. Each is arranged on the circumference. In this example, the injection holes 35 are the large injection holes 35a and the small injection holes 3 at intervals of 90 ° on the circumference.
5b are alternately drilled, and on the circumference different from this, small nozzle holes 35b and large nozzle holes 35a are alternately drilled at the same position in the axial direction, contrary to the above arrangement. The injection hole 35 may have a circular cross section or a polygonal cross section perpendicular to the axis. In the latter case, the change amount of the injection hole area per unit rotation angle can be increased.

A rotary valve 7 is installed in the hole 34. The rotary valve 7 is rotated at a predetermined rotation angle by a drive shaft system 8 penetrating the needle valve 4, the adjusting screw 102, and an actuator 9 attached to the drive head 2. Specifically, a first hole 45a is formed in the axial direction from the lower end of the needle valve 4 to an intermediate position, a second hole 45b thinner than the first hole 45a is formed from the end of the first hole 45a, and the end of the second hole 45b is formed. To the upper end of the push rod 101, a third hole 45c having the same diameter as the first hole 45a is formed, and the adjusting screw 102 is provided with a fourth hole 45d from the lower end to the upper end. Fourth hole 45
In order to prevent the drive shaft from being shaken, the diameter d is appropriately smaller in the upper end region than in other regions. The drive shaft system 8 is provided with a drive shaft main body 8a reaching the drive head 2, a joint shaft 8b, and a coupling 10 in this embodiment. The drive shaft main body 8a has a length reaching from the fourth hole 45d to the lower end region of the third hole 45c, and the diameter thereof is appropriately smaller than that of the third hole 45c. Since the joint shaft 8b functions as a seal portion, it has a large-diameter portion (face seal portion) 80 rotatably and precisely fitted in the first hole 45a, and a second hole is provided above the end of the large-diameter portion 80. A small-diameter portion 81 that is loosely fitted to the 45b is continuously provided. Therefore, a stopper step portion 82 is formed at the boundary portion between the small diameter portion 81 and the large diameter portion 80, and this is the first hole 45.
By contacting the upper end surface of a, the needle valve 4 can be moved up and down integrally. And the small diameter portion 81
Is connected to the lower end of the drive shaft main body 8a by joint parts 811 and 801 of an Oldham type or the like which allows axial play.

The rotary valve 7 has a large-diameter portion 8 of the joint shaft 8b via a coupling 10 which allows axial play.
Connected to 0. The coupling 10 allows rotational torque and holding torque to the rotary valve 7 while allowing misalignment between the rotor valve 7 and the joint shaft 8b and axial play of the rotary valve 7 caused by axial dimension processing error and needle valve lift. The Oldham coupling is used in the embodiment. The coupling 10 has an outer diameter smaller than the hole diameter of the first hole 45a, and a projection piece 800 extending from the lower end of the large diameter portion of the joint shaft 8b is fitted in the groove 10a of the upper half portion, and is 90 degrees with the groove 10a. A projecting piece 70 formed at the upper end of the rotary valve 7 is fitted in the groove 10b in the lower half of which the phase is shifted. Of course, the relationship between the protrusion and the groove may be reversed. Further, in the coupling, both the upper half and the lower half may be projections or grooves, and in this case, the joint shaft 8b and the rotary valve 7 are provided with corresponding grooves or projections.

The actuator 9 is fixed to a space 200 provided in the driving head 2. Actuator 9
Is arbitrary as long as it has a characteristic capable of rotating (preferably reversible rotation) and holding at a predetermined rotation position, and for example, a stepping motor or a servo motor is used. The output shaft and the upper end of the drive shaft body 8a are connected by a transmission element 90 such as an eccentric pin or a gear.

The rotary valve 7 is slidably fitted on the straight cylindrical wall of the hole 34 in the same manner as a conventional rotary valve, but in the present invention, the rotary valve 7 has an inclination angle α with respect to the axis. Band-shaped shield 7 having
Have two. In this embodiment, the shielding portion 72 is configured by providing a disc-shaped member having a predetermined inclination angle integrally with the central shaft portion 71, and the disc-shaped member is opened in the vertical direction. A plurality of fuel passages 73 are provided at predetermined intervals. In FIG. 4A, the fuel passage 73 is obtained by forming a notch on the outer periphery of the disk-shaped member.
In (b), the fuel passage 73 is obtained by a through hole penetrating the thickness of the disk-shaped member. The disc-shaped member is positioned in the axial direction by the lower end of the shaft portion 71 contacting the bottom of the hole 34, and in this state, the large injection hole 35a is shielded by the disc-shaped member as the shield portion 72. Meanwhile, the small injection hole 35b
Is not blocked by the disk-shaped member and communicates with the inside of the hole. At this time, the fuel passages 73 are out of alignment with the large injection holes 35a and the small injection holes 35b, that is, in the case of four injection holes on one circumference, they are out of phase with each other by 90 degrees on the circumference. It is preferably provided in a position.

FIG. 5 shows the relationship between the shielding portion 72 and the injection holes when fuel is injected from the four injection holes in an expanded state.
90 small jet holes 35b and large jet holes 35a are formed on the basic circumferential line L _1.
The small injection holes 35a and the small injection holes 35b are arranged alternately at an interval of 1/4 circle and above the basic circumferential line L ₁ at 360 ° intervals. 35b and the large injection hole 35a are arranged on the same axis, and a large injection hole 35a and a small injection hole 35b are provided at a position lower than the basic circumference line L ₁ and 180 degrees apart from the upper injection hole 35a. The small injection holes 35b and the large injection holes 35a are arranged on the same axis. A fuel passage 73 is provided in the shielding portion 72 so that the shielding portion 72 is always located at the position of the small injection hole or the large injection hole and at a position displaced from the injection hole position by 45 degrees.

6 to 10 show another embodiment of the rotary valve 7 used in the present invention. In the embodiment of FIG. 6, a plurality of strip-shaped shield portions 72 (two in the drawing) having an inclination angle α with respect to the axis are provided above and below. That is,
The shield portion 72 is configured by integrally providing two disk-shaped members having a predetermined inclination angle in parallel with the central shaft portion 71, and the disk-shaped members have a notch that opens in the vertical direction. Alternatively, a plurality of fuel passages 73 formed of grooves are provided at intervals in the circumferential direction. In the embodiment shown in FIG. 7, a strip-shaped shield 72 having an inclination angle α with respect to the axis is spirally provided. That is, the shield portion 72 is configured by spirally providing a disk-shaped member having a predetermined inclination angle (lead) integrally with the central shaft portion 71. In this embodiment, a plurality of fuel passages 73 opening in the vertical direction are provided at intervals in the circumferential direction, but this is not always necessary. FIG.
In this embodiment also, the strip-shaped shield portion 72 having an inclination angle α with respect to the axis is provided in the shape of a spoiler, but in this embodiment, the shield portion is composed of a shaft-like body, and a spiral groove is formed on the peripheral surface thereof. 7
4 are formed.

6 to 8, the injection holes 35 having different diameters, for example, the large injection holes 35a and the small injection holes 3 are formed in the hole wall.
5b are alternately arranged at predetermined intervals in the circumferential direction, and large injection holes 35a and small injection holes 35b are alternately provided at predetermined intervals on the circumference different from this. are doing. The relationship between the position of the injection hole and the position of the shielding portion is illustrated as a development view in FIG. 10, and the arrangement of the injection hole is the same as that in the embodiment of FIG. Then, while the rotary valve 7 is located in the hole 34, for example, all the large injection holes 35a, 3
The thickness and the inclination angle of the shielding portion are set so that 5a or the small injection holes 35b, 35b are opened.

In the embodiment, the injection hole 35 is formed on the basic circumference line.
Is composed of two large injection holes 35a and two small injection holes 35b, but it is not limited to this, and there may be three large injection holes or four small injection holes. In these cases, the size of the injection hole may be large, medium or small. Further, the shielding portion 72 may have three or more stages instead of two stages.

The timing of rotating the rotary valve 7 by the actuator 9 is preferably a period during which no axial force is applied to the drive shaft 8 by the internal cylinder pressure, that is, during the intake stroke or exhaust stroke of the engine.
In this rotation timing control, the actuator 9
It is electrically connected to a controller composed of U, etc., and a signal from the rotation speed detection sensor (or rotation angle detection sensor) of the engine or the fuel injection pump is input to the input part of this to determine that the engine is in the above stroke. The drive signal may be output to the actuator 9 when this is done. Then, a signal from a load detection sensor such as a rack sensor of the fuel injection pump is input to the controller at the same time, and a predetermined drive amount (driving rotation angle) to the actuator by a predetermined map formed in advance from the data of the load and the rotational speed, for example, Large injection hole 35 at low speed and low load
It is preferable to provide a driving amount such that the position where the shielding portion 72 contacts a is switched to the position where the shielding portion 72 contacts the small injection hole 35b at high speed and under high load.

[0020]

Next, the operation of the embodiment of the present invention will be described. The pressurized fuel is sent from the fuel injection pump (not shown) to the pressurized fuel port 104 through the pipe, is pushed into the oil sump 301 through the passage holes 105 and 305, and then descends from the annular fuel passage A. At the same time, this fuel pressure acts on the pressure receiving surface 42 of the nozzle needle 4 located in the oil sump 301, and when the fuel pressure reaches a pressure exceeding the setting force of the spring 103, the needle valve 4 is lifted and the lower end of the needle valve 4 is lifted. The seat surface 44 separates from the seat surface 303 of the nozzle body 3 and opens the valve. As a result, the pressurized fuel flows into the holes 34. When the needle valve 4 is lifted, the joint shaft 8b
Also moves integrally with the needle valve 4. When the fuel pressure decreases, the needle valve 4 is pushed down and closed by the urging force of the spring 103, fuel injection ends, and the joint shaft 8b descends together with the needle valve 4.

To control the rotational position of the rotary valve 7, that is, to select the injection hole 35, a drive signal is sent from the controller to the actuator 9 at the timing of the intake stroke or the exhaust stroke, for example, the rotation speed of the engine or the fuel injection pump.
(Or rotation angle) and the load, the output shaft is driven to the required rotation angle, which is transmitted through the transmission element 90 to the drive shaft main body 8a.
It is carried out by being transmitted to. For example, in the embodiment shown in FIGS. 2 to 4, the shielding portion 72 of the rotary valve 7 is arranged at the low load when the engine is started and at the low rotation speed as shown in FIG.
It is located at the position (a), so that a total of four large injection holes 35a on the basic circumference line and above and below the basic circumference line are covered by the shielding portion 7.
Since it is blocked by 2, the pressurized fuel is injected from the four small injection holes 35b communicating with the hole 34. Since the rotary valve 7 has the fuel passage 73 in the vertical direction, the pressurized fuel does not close in the axial direction and smoothly flows into the lower side of the rotary valve 7 and is injected in a pressure equalized state.

Further, when the engine is under high load and high rotation, the rotary valve 7 is rotated by a quarter circumference, and in this way, the shielding portion 72 changes from the state shown in FIG. As shown in (b), the small fuel holes 35b on the basic circumference and on the upper and lower sides thereof are shielded by the shielding portion 72, so that the pressurized fuel is pressurized by the fuel passage 73.
It is ejected only from the large injection hole 35a that communicates with the hole 34 via the. Further, if the rotary valve 7 is further rotated from this position by 1/4 circumference, the large injection hole 35a on the basic circumference is closed as shown in FIG. The lower large injection hole 35a is not shielded. Therefore, in this case, two large injection holes 35a and four small injection holes 3 are formed.
Injection is performed simultaneously from 5b. This FIG.5 (c) is
When used in a low load, low rotation to high load, medium load range between high rotation and medium rotation, an ideal spray state can be obtained.

When the rotary valve 7 of the embodiment shown in FIGS. 6 to 8 is used, all the large injection holes 3 are formed by the upper and lower shielding portions 72, 72 as shown in FIG. 10 (a).
Since the 5a and 35a are shielded, the small injection holes 35b and 35b
When the rotary valve 7 is rotated by 1/4 circumference length from this state, pressurized fuel is injected from the shielding portions 72, 72.
Move in parallel, and as shown in FIG.
Since all the small injection holes 35b, 35b are shielded by, the pressurized fuel is injected from the large injection holes 35a, 35a.

By switching the injection holes, the fuel injection pressure is increased as the area of the injection holes is reduced when the load is low.
The injection period becomes longer. This promotes atomization of the spray,
An increase in the excess air ratio of the spray can be expected, and NOx will be reduced. Further, at the time of high load, the fuel injection pressure is lowered with the increase of the injection hole area, and the injection period is shortened. As a result, the spray having a required flow rate can be uniformly dispersed and supplied as a whole under high load, and stable high-power combustion can be performed.

In the present invention, even if the injection holes are switched by rotating the rotary valve 7 as described above, the injection direction is always constant in the nozzle circumferential direction and changes only in the nozzle axial direction. Therefore, even when the injection nozzle is attached to the ball-shaped combustion chamber at an oblique angle, the spray direction does not change, so the positional relationship with the center of the cylinder does not shift, and the dead zone does not occur. Can be formed.

[0026]

According to the present invention described above, a plurality of injection holes having different diameters are arranged at intervals on the peripheral wall of the hole for guiding the pressurized fuel to the tip of the nozzle body, while sliding in the hole. Since a rotary valve that can be dynamically rotated is arranged and the rotary valve has a band-shaped shielding portion that has an inclination angle with respect to the valve axis, rotating the rotary valve results in different hole diameters in the nozzle axis direction. Since the fuel can be injected from the injection hole, and the fuel injection position in the circumferential direction is always constant, NOx can be injected with proper spraying even if there are restrictions on the installation position of the injection nozzle and the shape of the combustion chamber.
It has the excellent effect of reducing smoke and smoke and improving fuel efficiency.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional side view showing a first embodiment of the present invention.

FIG. 2 is a partially enlarged view of FIG.

FIG. 3 is a front view of the tip portion in FIG.

FIG. 4 is a perspective view of a rotary valve applied to FIG.

FIG. 5 is an explanatory view showing the relationship between the injection holes and the shielding portion of FIG. 1 in a developed state.

FIG. 6 is a perspective view showing another embodiment of the rotary valve according to the present invention.

FIG. 7 is a perspective view showing another embodiment of the rotary valve according to the present invention.

FIG. 8 is a perspective view showing another embodiment of the rotary valve according to the present invention.

FIG. 9 is a cross-sectional view of a nozzle tip portion using the rotary valve of FIGS. 6 and 7.

FIG. 10 is an explanatory view showing a developed state of the relationship between the injection hole and the shielding part when the rotary valve of FIGS. 6 to 8 is used.

FIG. 11 is an explanatory view showing a cross section of a conventional injection hole switching type injection nozzle and a state at the time of switching the injection hole.

[Explanation of symbols]

 3 Nozzle body 4 Needle valve 7 Rotary valve 34 Hole 35 Injection hole 35a Large injection hole 35b Small injection hole 72 Strip-shaped shield 73 Fuel passage

Continued Front Page (72) Inventor Masanori Amamori 3-13-26, Yasumicho, Higashimatsuyama, Saitama Stock Company XXEL Higashimatsuyama Factory (72) Takashi Kobayashi 3--1326, Yasumimachi, Higashimatsuyama, Saitama Ceremony Company Zexel Higashi Matsuyama Factory

Claims (3)

[Claims] 1. A hole for introducing pressurized fuel is formed at the tip of a nozzle body, a needle valve which is opened and closed by a predetermined fuel pressure is arranged at the inlet side of the hole, and a plurality of holes having different diameters are provided on the peripheral wall of the hole. While arranging the injection holes at intervals, a rotary valve capable of sliding rotation is arranged in the hole, and the rotary valve has a band-shaped shield portion having an inclination angle with respect to the valve axis. Fuel injection nozzle with switchable injection holes. 2. The injection hole switching type fuel injection nozzle according to claim 1, wherein the strip-shaped shield portion is made of a disk-shaped member having a fuel passage in the vertical direction. 3. The injection hole switching type fuel injection nozzle according to claim 1, wherein the strip-shaped shield portion is made of a spiral member.