JPH11141434A - Fuel injection nozzle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection nozzle capable of suppressing jumping of a needle 2 and easily adjusting a dump distance and checking valve performance without being limited by a nozzle size. A large-diameter hole (36) for accommodating a piston (18) at an upper end of a needle (2) is formed below a tip packing (7) between a nozzle body (3) and a nozzle holder (6). A second damper chamber 36b is formed above the chamber 36a. The chip packing 7 includes a communication passage 35 for opening and closing the first damper chamber 36a, and an upper opening of the communication passage 35 is open to the chamfered portion 42,
It is opened and closed by the spring seat 31. The spring seat 31 includes a spring seat pressing member 32. When the movement amount of the piston 18 is larger than the pre-lift amount PL, the spring seat 31 is pushed up by the spring seat pressing member 32 to open the communication passage 35. Conversely, if the movement amount of the piston 18 is smaller than the pre-lift amount PL, the spring seat 31 closes the communication passage 35 by the action of the second spring 33, and a damper effect occurs.

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 for injecting fuel pumped from a fuel pump into an internal combustion engine, and more particularly to a technique for suppressing jumping of a needle which occurs when the needle closes the fuel injection port. Things.

[0002]

2. Description of the Related Art JP-A-59-19 discloses a technique for suppressing jumping of a needle which occurs when the needle is seated on a nozzle body so that the needle closes a fuel injection port.
A technique disclosed in Japanese Patent No. 0472 is known. In this technique, as shown in FIG. 7, a large-diameter piston J2 is provided at the upper end of a needle J1 (an end on a side different from the fuel injection port), and a nozzle body J3 is provided with an outer diameter substantially equal to the outer diameter of the piston J2. A sliding wall J4 of the same size is provided, and a damper chamber J5 (chamber filled with fuel) for dumping the movement of the piston J2 is provided in the sliding wall J4 below the piston J2 (fuel injection side). is there. And below the side of piston J2,
A notch J6 communicating with the damper chamber J5 is provided, and a large diameter portion J7 for forming a gap between the sliding wall J4 and the piston J2 is provided above the sliding wall J4.

[0003] In the conventional fuel injection nozzle provided as described above, when the piston J2 moves upward (in the direction of opening the fuel injection port) by a predetermined amount or more together with the needle J1, the upper end of the notch J6 on the outer periphery of the piston J2 has a diameter. The damper chamber J5 is opened to communicate with the gap of the large part J7, and the dump of the piston J2 is released. Conversely, when the needle J1 moves downward (to close the fuel injection port), During the movement of the piston J2, the notch J6 of the piston J2 and the large diameter J
7, the communication with the gap is interrupted, and the movements of the needle J1 and the piston J2 are dumped. As a result, when the needle J1 closes the fuel injection port, the movement of the needle J1 is dumped just before the needle J1 is seated on the nozzle body J3.
Jumping that occurs when seating 1 is reduced.

[0004]

In the above-described conventional fuel injection nozzle, the dump release position and the start position are set by the upper end position of the notch J6 and the lower end position of the large-diameter portion J7. However, it is necessary to measure the distance to the upper end of the notch J6 and the distance to the lower end of the large-diameter portion J7 based on the seating portion of the needle J1, and adjust the difference between the distances. It is difficult to measure the distance to the upper end of the notch J6 and the distance to the lower end of the large-diameter portion J7 easily and with high accuracy based on the seating portion of the needle J1, and it is difficult to adjust the dump distance. Met.

Further, the fuel injection nozzle is required to have high-precision valve performance. However, in the prior art, the damper effect of the needle J1 is always added to the valve performance. For this reason, it is difficult to check the valve performance required for the fuel injection nozzle, and the valve performance tends to vary.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above circumstances, and has as its object to suppress the jumping of the needle when the needle is seated closing the fuel injection port, and to dump the fuel without being limited by the nozzle size. It is an object of the present invention to provide a fuel injection nozzle that can easily adjust a distance and check valve performance.

[0007]

[Means for Solving the Problems] [Means of Claim 1] By adopting claim 1, the following actions and effects can be obtained. (Operation at the time of increase in fuel supply pressure) When the injected fuel is supplied to the fuel injection nozzle, a force is generated in the direction in which the fuel injection opening opens to the needle due to the fuel supply pressure. When the supply pressure force applied to the needle and the piston becomes larger than the urging force of the first urging means as the supply pressure rises, the needle and the piston close the fuel injection port by overcoming the urging force of the first urging means. Move in the open direction.

When the moving amount reaches the pre-lift amount, the urging force of the second urging means in addition to the urging force of the first urging means is applied to the needle and the piston via the spring seat and the spring seat pressing member. Added. Then, the supply pressure further increases, and the force of the supply pressure applied to the needle and the piston is
When the urging force is larger than the urging force of the first urging means and the second urging means, the needle and the piston further move in a direction to open the fuel injection port.

Here, when the needle and the piston move in the direction to open the fuel injection port, the communication passage is closed by the spring seat until the movement amount reaches the pre-lift amount. The damper chamber becomes closed with the outside and dumps the movement of the piston and needle,
Since the range in which the damper effect occurs is the rising portion of the needle and the piston, the damper effect given to the piston and the needle is small. When the movement amount of the needle and the piston becomes larger than the pre-lift amount, the piston presses the spring seat pressing member, and the spring seat separates from the tip packing. That is, the communication passage is opened. As a result, the first damper chamber is opened, and the damper effect of the piston by the first damper chamber is lost.

When the needle and the piston move in the direction to open the fuel injection port, the second damper chamber is always in communication with the spring chamber in the nozzle holder through the escape hole. The damper effect of the piston by the two damper chambers can be varied, and the rising characteristics of the nozzle lift can be changed.

(Operation at the time of decrease in fuel supply pressure) When the supply pressure of fuel decreases and the needle and piston move in the direction to close the fuel injection port, the movement of the needle and piston decreases to the pre-lift amount. During this period, the needle and the piston move in the direction to close the fuel injection port by the urging forces of the first and second urging means. At this time,
The spring seat is separated from the tip packing by the spring seat pressing member, and the communication passage is opened. As a result, the first
The damper chamber is opened, and the needle and the piston move in the direction to close the fuel injection port without being hindered by the damper effect.

When the movement amount of the needle and the piston becomes smaller than the pre-lift amount, the urging force of the second urging means is lost. Further, the spring seat comes into contact with the chip packing, and the communication path is closed. For this reason, the first damper chamber generates a damper effect, and dumps the movement of the piston and the needle at the moving speed. As a result, the speed at which the needle sits on the nozzle body is suppressed, and jumping of the needle is suppressed.

(Effect of Claim 1) As described above, jumping when the needle is seated on the nozzle body is suppressed. The dump distance can be measured only by measuring the pre-lift amount. That is, since the dump distance can be adjusted only by adjusting the pre-lift amount, the adjustment of the dump distance becomes easier as compared with the related art.

At the time of checking the valve performance, the damper effect can be easily prevented from being generated. As a specific example, the damper effect does not occur between the nozzle body alone and the needle alone. As described above, since the valve performance can be checked without being affected by the damper effect, the valve performance can be checked with high accuracy, and a fuel injection nozzle having excellent valve performance and less variation in valve performance can be produced.

Here, for example, when the communication path is opened at the end face of the chip packing, in order to increase the opening area of the communication path for releasing the pressure of the first damper chamber, the cross-sectional area of the communication path must be increased. Therefore, it is necessary to secure the chip packing, and the applicable chip packing diameter is limited. However, according to the first aspect of the present invention, the communication passage is provided on the spring seat side so as to open to the chamfered portion. For this reason, the opening area of the communication passage for releasing the pressure of the first damper chamber can be sufficiently secured as (outer diameter of the chamfered portion) × π × (maximum lift amount−prelift amount), and the limitation of the applicable nozzle size Will not receive. That is, even if the chip packing diameter is small, the opening area of the communication passage for releasing the pressure in the first damper chamber can be increased. That is, the above effects can be obtained from the small diameter fuel injection nozzle to the large diameter fuel injection nozzle.

[Means of Claim 2] By adopting claim 2 and providing the spring seat pressing member integrally with the spring seat, the number of parts is reduced and the assembly is facilitated. Therefore, the manufacturing cost of the fuel injection nozzle can be reduced.

According to the third aspect of the present invention, the spring seat pressing member is provided integrally with the piston, so that the pre-lift amount can be reduced by the tip packing seat surface with which the spring seat contacts, and the spring seat pressing member. And can be measured by the difference. That is, the measurement of the pre-lift amount becomes easy.

[0018]

Next, embodiments of the present invention will be described based on three examples and modifications. First Embodiment FIGS. 1 to 4 show a first embodiment, and FIG. 2 is a sectional view of a fuel injection nozzle. The fuel injection nozzle 1 of this embodiment is of a direct injection type that is attached to each cylinder of a diesel engine (not shown) and injects fuel pumped from a fuel pump (not shown) directly into the combustion chamber in a mist state. 2, a nozzle holder 6 that accommodates the first and second urging means 4, 5, a chip packing 7 disposed between the nozzle body 3 and the nozzle holder 6, and via the chip packing 7. And a retaining nut 8 for fixing the nozzle body 3 and the nozzle holder 6 to each other.

The nozzle body 3 has a tip (lower side in the figure).
And one or more fuel injection ports 11 for injecting fuel. Inside the nozzle body 3, a sliding hole 12 for slidably holding the rod-shaped needle 2 is formed. An oil reservoir 13 having an enlarged hole diameter is provided at an intermediate portion of the sliding hole 12. Further, the nozzle body 3 is provided with a fuel delivery path 14 extending from the upper end face in the figure (the contact face with the chip packing 7) to the oil sump 13. The fuel delivery path 14 communicates with a fuel supply path 15 (described later) of the nozzle holder 6 and a fuel relay path 16 (described below) of the chip packing 7 to form a fuel passage.

The needle 2 has a sliding hole 1 in the nozzle body 3.
2 is slidably held in the nozzle body 2, and the tip (lower side in the figure) is seated in and detached from the nozzle body 3.
The fuel injection port 11 is closed and opened. The needle 2 is provided with a small diameter on the lower side of the oil reservoir 13 (on the side of the fuel injection port 11) in the figure and on the upper side of the oil reservoir 13 (on the side of the nozzle holder 6) with a larger diameter. Oil pool 13
In the upper part of the figure, a pressure receiving portion 17 is formed by a step. Then, when the pressure of the fuel supplied to the oil sump 13 increases, the increased pressure is received by the pressure receiving portion 17 and converted into a force for moving the needle 2 upward in the drawing.

The outer diameter of the small-diameter portion 2 a of the needle 2 (below the pressure receiving portion 17 in the figure) is determined by the sliding hole 12
The sliding hole 12 and the small-diameter portion 2
a is provided so that the supplied fuel can easily flow there between. The outer diameter of the large diameter portion 2b of the needle 2 (above the pressure receiving portion 17 in the drawing) is provided slightly smaller than the inner diameter of the sliding hole 12, and the needle 2 slides without sliding in the sliding hole 12. It is provided to move.

On the side of the needle 2 different from the fuel injection port 11 (upper end in the figure), a piston 18 having a larger diameter than the outer diameter of the needle 2 is integrally provided. The piston 18 has a large-diameter hole (described later) of the chip packing 7.
And the first and second urging means 4, 5
Is transmitted to the needle 2 and the movement of the needle 2 is suppressed by the damper effect of the first and second damper chambers (described later).

The nozzle holder 6 has the first urging means 4 therein.
A cylindrical spring chamber 21 for accommodating the second urging means 5 is provided. The inner diameter of the spring chamber 21 on the lower side in the figure from the intermediate step 22 is larger than the inner diameter on the upper side in the figure. Further, the nozzle holder 6 is provided with a connection portion 23 for receiving the supply of the fuel pumped from the fuel pump. Inside the connection portion 23 and around the spring chamber 21, the supplied fuel is supplied to a sump 13 through a fuel relay passage 16 (described later) of the chip packing 7 and a fuel delivery passage 14 of the nozzle body 3. A fuel supply path 15 is provided for sending the fuel to the fuel tank. Further, the nozzle holder 6
A fuel release passage 24 for returning the fuel guided to the spring chamber 21 to a fuel tank (not shown) is provided on the upper side of the drawing.

The first biasing means 4 always biases the needle 2 in the direction in which the fuel injection port 11 closes.
5 and a pressure pin 26. First spring 2
Reference numeral 5 denotes a compression coil spring disposed above the step 22 of the spring chamber 21 in the drawing, and the biasing force thereof is adjusted by the thickness of the first shim 27 disposed in the drawing. Pressure pin 2
Reference numeral 6 denotes a rod for transmitting the urging force of the first spring 25 to the needle 2 via the piston 18, and has a flange 28 at the upper end in the figure for receiving the urging force of the first spring 25. The pressure pin 26 is slidably held on the upper side in the figure by a spacer 29 provided in the spring chamber 21, and has a lower end in the figure as a spring seat 31 (described later) and a spring seat pressing member 3.
2 (described later) is slidably held inside. In addition,
The spacer 29 is arranged in the spring chamber 21 while being pressed against the step 22 by the action of a second spring 33 (described later) of the second urging means 5.

The second biasing means 5 controls the fuel injection port 1 when the amount of movement of the needle 2 in the direction of opening the fuel injection port 11 is larger than a preset lift amount (described later).
The spring 2 biases the needle 2 in a direction to close the spring 1 and includes a second spring 33, a spring seat 31, and a spring seat pressing member 32 provided integrally with the spring seat 31. Second spring 33
Is a compression coil spring disposed below the step 22 of the spring chamber 21 in the drawing, and the biasing force thereof is adjusted by the thickness of the second shim 34 disposed above the second spring 33 in the drawing.

The spring seat 31 is a ring member that is disposed below the second spring 33 in the drawing and receives the urging force of the second spring 33.
The pressure pin 26 is inserted inside. As shown in FIG. 1, the spring seat 31 closes a communication passage 35 (described later) formed in the chip packing 7 with its lower surface illustrated in contact with the illustrated upper surface of the chip packing 7.

The spring seat pressing member 32 is provided integrally with the spring seat 31 in this embodiment, as described above. As shown in FIG. 1, the spring seat pressing member 32 is provided at a distance from the lower end of the drawing to the piston 18 with the needle 2 closing the fuel injection port 11.
The distance from the lower end of the drawing to the upper end of the drawing of the piston 18 is
It becomes the pre-lift amount PL. That is, when the needle 2 and the piston 18 move upward in the figure and the movement amount reaches the pre-lift amount PL, the piston 18 is moved to the spring seat pressing member 32.
And the urging force of the second spring 33 is transmitted to the needle 2 via the piston 18. When the needle 2 and the piston 18 move upward in the drawing with the piston 18 in contact with the spring seat pressing member 32, the spring seat 31 also moves upward in the drawing with the movement of the spring seat pressing member 32, and the spring seat 31 Is separated from the upper surface of the chip packing 7 in the figure.

Since the chip packing 7 is disposed between the nozzle body 3 and the nozzle holder 6, the tip packing 7 communicates the fuel delivery path 14 of the nozzle body 3 with the fuel supply path 15 of the nozzle holder 6. Are provided. The chip packing 7 has a large-diameter hole 36 formed therein for accommodating the piston 18 on the lower side in the drawing, and a small-diameter hole 37 for inserting the pressure pin 26 and the spring seat pressing member 32 on the upper side in the drawing. Have been.

The axial dimension of the large-diameter hole 36 is
Is larger than the dimension in the axial direction. The maximum lift amount ML is determined by the step between the large-diameter hole 36 and the small-diameter hole 37.
Is determined. With this arrangement, the regulating surface 38 and the piston 18 are provided apart from each other with the needle 2 closing the fuel injection port 11, and the distance between the regulating surface 38 and the upper end of the piston 18 in the drawing is reduced. , The maximum lift amount ML. That is, needle 2
And the piston 18 move upward in the figure,
When the abutment 8 comes into contact with the regulating surface 38 of the tip packing 7, the movement amount of the needle 2 has reached the maximum lift amount ML.

The inner diameter of the large-diameter hole 36 is slightly larger than the outer diameter of the piston 18, and is provided between the large-diameter hole 36 and the piston 18 so that fuel does not easily pass through. Have been. Therefore, the first damper chamber 36a formed below the piston 18 in the large-diameter hole 36 in the drawing.
When the communication path 35 described later is closed, the volume inside cannot easily change, and as a result, acts to dump the movement of the piston 18. On the other hand, the inside of the second damper chamber 36b formed in the large-diameter hole 36 above the piston 18 in the drawing is always in communication with the spring chamber 21 through the relief hole 41. It is provided to discharge the fuel accumulated in the chamber 36b.

The first and second damper chambers 36a, 36b
The inside is filled with fuel. This is because the fuel pressure in the oil sump 13 is higher than the pressure on the side of the fuel release passage 24, and the fuel in the oil sump 13 passes between the needle 2 and the sliding hole 12 and passes through the large-diameter hole 36, It is transmitted to the fuel release passage 24 through the small diameter hole 37 and the spring chamber 21. As a result, the first and second damper chambers 36a and 36b are always filled with fuel.

The corner between the small diameter hole 37 and the seating surface of the chip packing 7 on which the spring seat 31 is seated is chamfered to form a chamfered portion 42. The chip packing 7 is provided with a communication passage 35 that connects the chamfered portion 42 and the first damper chamber 36a. This communication passage 3
5 is a communication hole 35a extending in the vertical direction, and a communication hole 35a and a first damper chamber 36a on the lower side of the chip packing 7 in the drawing.
And a communication groove 35b (see FIG. 3) that connects When the spring seat 31 is seated on the chip packing 7, the chamfered portion 42, which is the upper outlet in the drawing, of the communication passage 35 is closed by the spring seat 31, and the volume of the first damper chamber 36 a cannot be easily changed. Thus, the movement of the piston 18 is dumped. Further, in a state where the spring seat 31 is separated from the chip packing 7, the chamfered portion 42, which is an outlet opening on the upper side in the drawing of the communication path 35, is opened, and as a result, the volume of the first damper chamber 36a can be easily changed. The damping effect of the piston 18 by the first damper chamber 36a is eliminated. Reference numeral 43 in FIG. 3 denotes a pin hole through which a knock pin (not shown) for preventing positioning and rotation of the nozzle body 3, the chip packing 7, and the nozzle holder 6 is inserted.

[Operation of Embodiment] Next, the operation of the above embodiment will be described with reference to FIG. (Operation at the time of increasing the supply pressure of fuel) When the fuel pump pumps fuel for fuel injection, the pumped fuel flows through the fuel supply passage 15, the fuel relay passage 16, and the fuel delivery passage 14 into an oil sump 13. Supplied to Then, the pressure receiving portion 17 of the needle 2 receives the pressure of the fuel supplied to the oil sump 13,
A force is generated in the needle 2 in a direction in which the fuel injection port 11 opens. When the force applied to the needle 2 and the piston 18 becomes larger than the urging force of the first urging means 4 (see FIG. 4A) with the increase of the supply pressure, the urging force of the first urging means 4 is overcome. The needle 2 and the piston 18 move in a direction to open the fuel injection port 11 (see FIG. 4A to FIG. 4B). As a result, the fuel injection port 11 starts to open, and the fuel pumped to the oil sump 13 is injected from the fuel injection port 11 into the combustion chamber.

When the movement amount of the needle 2 reaches the pre-lift amount PL (see FIG. 4B), the needle 2 and the piston 18 have the second urging means 5 in addition to the urging force of the first urging means 4. Is applied via the spring seat 31 and the spring seat pressing member 32. Then, the supply pressure further increases, and the force of the supply pressure applied to the needle 2 and the piston 18 becomes
When the urging force of the first urging means 4 and the second urging means 5 becomes larger than the urging force (see FIG. 4C), the needle 2 and the piston 18 further move in a direction to open the fuel injection port 11 (FIG. 4). C to d). As a result, the fuel injection port 11 is further opened, and the amount of fuel injected from the fuel injection port 11 into the combustion chamber increases.

When the movement amount of the needle 2 reaches the maximum lift amount ML, the end of the piston 18 comes into contact with the regulating surface 38 of the large-diameter hole 36 (see FIG. 4D). For this reason, even if the fuel pressure supplied to the oil sump 13 further increases, the lift of the needle 2 and the piston 18 is stopped (see d to e in FIG. 4). As a result, the opening of the fuel injection port 11 becomes constant, and a constant (maximum) fuel is injected from the fuel injection port 11 into the combustion chamber.

Here, the communication passage 35 is closed by the spring seat 31 until the movement amount of the needle 2 and the piston 18 reaches the pre-lift amount PL (see FIGS. 4A to 4B). Therefore, the first damper chamber 36a is closed with the outside, and the movement of the piston 18 is dumped. However, since the range where the damper effect occurs is the rising portion of the needle 2 and the piston 18, the damper effect given to the piston 18 and the needle 2 is small.
When the movement amount of the needle 2 and the piston 18 becomes larger than the pre-lift amount PL (see FIG. 4B and thereafter), the piston 18 presses the spring seat pressing member 32,
The spring seat 31 separates from the chip packing 7 and the communication path 3
5 is opened. As a result, the first damper chamber 36a is opened, the damping effect of the piston 18 by the first damper chamber 36a is eliminated, and the needle 2 and the piston 18 can quickly move to the maximum lift amount ML.

When the needle 2 and the piston 18 move in the direction to open the fuel injection port 11, the second damper chamber 3
6b is always in communication with the spring chamber 21 through the relief hole 41, so that the second damper chamber 36b depends on the diameter of the relief hole 41.
, The damper effect of the piston 18 can be varied. In the first embodiment, the diameter of the escape hole 41 is provided to be larger than that of the second embodiment described later, and the needle 2 rises quickly as shown in FIG.

(Operation at the time of decrease in fuel supply pressure) When the pressure of the fuel supplied to the oil sump 13 decreases and the needle 2 and the piston 18 move in the direction to close the fuel injection port 11, the needle 2 and the piston Until the movement amount of No. 18 decreases to the pre-lift amount PL (from e to f in FIG. 4).
Reference), the first and second urging means 4, 5
The fuel injection port 11 moves in the closing direction. In the initial stage of lowering, the spring seat 31 is separated from the chip packing 7 by the spring seat pressing member 32, and the communication passage 35 is opened. Therefore, the first damper chamber 36a is in an open state, the damper effect on the piston 18 by the first damper chamber 36a does not occur, and the needle 2 and the piston 18
Moves in the direction in which the fuel injection port 11 is closed by the urging forces of the first and second urging means 4 and 5.

When the movement amount of the needle 2 and the piston 18 becomes smaller than the pre-lift amount PL (from f to g in FIG. 4).
Reference), the urging force of the second urging means 5 disappears. Further, the spring seat 31 comes into contact with the chip packing 7 and the communication path 35 is closed. For this reason, the first damper chamber 36a generates a damper effect, and dumps the movement of the piston 18 whose moving speed has increased between f and e in FIG. Therefore, the speed at which the needle 2 is seated on the nozzle body 3 together with the piston 18 is suppressed (see the broken line α in FIG. 4). As a result, when the needle 2 is seated on the nozzle body 3 and the needle 2 closes the fuel injection port 11 (see g in FIG. 4), the needle 2 does not jump as shown by the solid line β in the reference example.

[Effects of the Embodiment] As described above, when the needle 2 moves in the direction to close the fuel injection port 11, the amount of movement of the fuel injection nozzle 1 of this embodiment is smaller than the pre-lift amount PL. When the distance becomes smaller, the first damper chamber 36a generates a damper effect, dumps the movement of the piston 18, and reduces the seating speed of the needle 2. As a result, the needle 2
Can be suppressed to almost zero when sitting on the nozzle body 3.

The dump distance can be measured only by measuring the pre-lift amount PL. That is, in the present embodiment, the pre-lift amount PL is determined by the axial dimension A of the tip packing 7, the axial dimension B of the spring seat pressing member 32, and the projection dimension C of the piston 18 from the nozzle body 3 (the needle 2 is the fuel injection port). 1
1) with a dial gauge, etc.
PL = ABC. As described above, in the present embodiment, since the pre-lift amount PL can be easily obtained, the adjustment of the dump distance can be easily performed as compared with the related art. In the first embodiment, since the spring seat pressing member 32 is provided integrally with the spring seat 31, the number of components is reduced, and the assembly is easy. Therefore, the manufacturing cost of the fuel injection nozzle 1 can be reduced.

By checking the valve performance between the single needle 2 and the single nozzle body 3, the valve performance can be checked without being affected by the damper effect. That is, the valve performance can be checked so that the damper effect does not easily occur as compared with the related art. For this reason, the valve performance can be checked with high accuracy, and the fuel injection nozzle 1 having excellent valve performance and less variation in valve performance can be produced.

The communication passage 35 is provided in the beveled portion 42 on the spring seat 31 side. Therefore, the first
The opening area of the communication hole 35a for releasing the pressure of the damper chamber 36a can be sufficiently secured as (outer diameter of the chamfered portion 42) × π × (maximum lift amount ML-prelift amount PL), and the applicable chip packing 7 can be used. Eliminates restrictions on outer diameter. That is, even if the tip packing 7 has a small diameter, the first damper chamber 3
The opening area for releasing the pressure of 6a can be increased.
That is, the present invention can be applied from the small-diameter fuel injection nozzle 1 to the large-diameter fuel injection nozzle 1, and the above effects can be obtained.

[Second Embodiment] FIG. 5 shows a second embodiment, and is a time chart for explaining the lift amount of the needle 2 (refer to the first embodiment for reference numerals). In this second embodiment,
The diameter of the escape hole 41 is made sufficiently smaller than that of the first embodiment. By providing in this way,
The same effect as in the above embodiment can be obtained, and the damping effect on the piston 18 by the second damper chamber 36b when the needle 2 and the piston 18 move in the direction to open the fuel injection port 11 can be increased. As shown by the solid line 5 in FIG. 5, the needle 2 slowly rises, so that noise can be reduced and exhaust gas can be purified.

[Third Embodiment] FIG. 6 shows a third embodiment and is a sectional view of a main part of a fuel injection nozzle 1. As shown in FIG. This third
In the embodiment, the needle 2 and the piston 18 are provided separately, and the piston 18 and the spring seat pressing member 32 are provided integrally. By providing in this way, the same effect as in the above embodiment can be obtained, and
The pre-lift amount PL can be measured by a step distance between the illustrated upper surface of the chip packing 7 and the illustrated upper surface of the spring seat pressing member 32. That is, in the third embodiment, the measurement of the pre-lift amount PL (dump distance) is further facilitated and the adjustment is further facilitated as compared with the first embodiment.

[Modification] The spring seat pressing member 32 is
1 or an example of being provided integrally with the piston 18 is shown,
The spring seat pressing member 32 may be provided separately from other members. By providing the spring seat pressing member 32 separately from the other members, the pre-lift amount can be determined by the step distance between the end surface of the chip packing 7 and the end surface of the spring seat pressing member 32, similarly to the second embodiment. PL (dump distance) can be measured.
In the above embodiment, the example in which the present invention is applied to the direct injection type fuel injection nozzle is described. However, the present invention may be applied to the sub-combustion chamber type fuel injection nozzle.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a fuel injection nozzle (first embodiment).

FIG. 2 is a sectional view of a fuel injection nozzle (first embodiment).

FIG. 3 is a bottom view of the chip packing (first embodiment).

FIG. 4 is a time chart for explaining a lift amount of a needle (first embodiment).

FIG. 5 is a time chart for explaining a lift amount of a needle (second embodiment).

FIG. 6 is a sectional view of a main part of a fuel injection nozzle (third embodiment).

FIG. 7 is a sectional view of a main part of a fuel injection nozzle (conventional example).

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 fuel injection nozzle 2 needle 3 nozzle body 4 first urging means 5 second urging means 6 nozzle holder 7 chip packing 11 fuel injection port 18 piston 21 spring chamber 22 step 31 spring seat 32 spring seat pressing member 35 communication passage 36 Large-diameter hole 37 Small-diameter hole 36a First damper chamber 36b Second damper chamber 41 Escape hole 42 Chamfered part PL Pre-lift amount

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁶ Identification code FI F02M 61/20 F02M 61/20 C

Claims (3)

[Claims] 1. A nozzle body having a fuel injection port for injecting fuel, and (b) a nozzle body movably held inside the nozzle body.
A needle that moves in a direction to open the fuel injection port by a supply pressure of fuel; (c) a nozzle holder that supports the nozzle body; and (d) a nozzle that is housed in the nozzle holder and closes the fuel injection port. First urging means for urging the needle; (e) when the amount of movement of the needle in the direction in which the fuel injection port is opened in the nozzle holder is larger than a pre-lift amount set in advance. A second urging means for urging the needle in a direction to close the fuel injection port, wherein: (f) the needle is provided on the side different from the fuel injection port in the first direction. And (g) between the nozzle body and the nozzle holder, the piston having a slightly larger diameter than the outer diameter of the piston between the nozzle body and the nozzle holder. A first damper chamber provided on the nozzle holder side with a small-diameter hole having a small diameter through the step with the large-diameter hole, and the piston accommodated in the large-diameter hole being provided on the fuel injection port side of the piston. A tip packing in which a second damper chamber is formed on a side of the piston different from the fuel injection port; (h) the second biasing means includes a spring seat pressed against the tip packing; (I) a spring seat pressing member is provided in the small diameter hole, the spring seat pressing member for transmitting the movement amount of the piston to the spring seat when the movement amount of the needle moves more than the pre-lift amount and separating the spring seat from the tip packing. (J) the chip packing includes a chamfered portion formed by chamfering a corner between the seating surface of the spring seat and the small diameter hole, and a communication passage communicating the chamfered portion with the first damper chamber. A fuel injection nozzle provided with a relief hole communicating the spring chamber in the nozzle holder with the second damper chamber. 2. The fuel injection nozzle according to claim 1, wherein the spring seat pressing member is provided integrally with the spring seat. 3. The fuel injection nozzle according to claim 1, wherein the spring seat pressing member is provided integrally with the piston.