JP2002168162A - Fuel injection nozzle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To process easily a nozzle body seat part and a nozzle needle seat part and to restrain abrasion in the nozzle body seat part and the nozzle needle seat part. SOLUTION: The nozzle needle seat part 22 has a straight shape without a ridge line. By forming a toroidal ridge line 16 for seating with the nozzle needle seat part 22 on the nozzle body seat part 12, stress in the seat part can be dispersed widely on the nozzle body seat part 12 larger in volume than the nozzle needle seat part 22 even when the nozzle needle seat part 22 sits on (collides with) the nozzle body seat part 12 for generating the stress in the seat part, accordingly the maximum stress in the seat part can be lowered. Thereby the abrasion in the nozzle needle seat part 22 and the nozzle body seat part 12 can be restrained. Since the seat part shape of a nozzle body 1 can be easily processed and the seat part shape of a nozzle needle 2 has a simple shape, manufacturing costs of a hole type fuel injection nozzle can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a fuel injection nozzle for spraying fuel into a combustion chamber of an internal combustion engine.
In particular, the present invention relates to a hall-type fuel injection nozzle for spraying fuel into a combustion chamber of a diesel engine.

[0002]

2. Description of the Related Art Conventionally, for example, in a Hall type fuel injection nozzle for spraying fuel into a combustion chamber of a diesel engine, as shown in FIG.
2 is seated. That is, the nozzle body 101
Seat 111 of the nozzle and seat 1 of the nozzle needle 102
21 collide. As a result, when wear occurs in the seat portion 111 of the nozzle body 101 and the seat portion 122 of the nozzle needle 102, the effective seat area changes, so that the valve opening pressure greatly changes and the seat portion 111 of the nozzle body 101 and the nozzle needle 102 However, there is a problem that the sealing performance with the sheet portion 122 is significantly reduced.

Therefore, the sheet portion 1 of the nozzle body 101
By providing an annular ridge line 123 on the seat portion 122 of the nozzle needle 102 for the purpose of suppressing wear of the seat portion 122 of the nozzle needle 102, the effective seat diameter is reduced due to the initial wear of the seat portion 122 of the nozzle needle 102. There is a hole type fuel injection nozzle (for example, Japanese Patent Application Laid-Open No. 9-189278) in which the seat portion 122 of the nozzle needle 102 is enlarged so as to reduce the maximum stress of the seat portion, thereby reducing the abrasion.

[0004]

However, in the conventional hole-type fuel injection nozzle, even if the abrasion of the seat portion 111 of the nozzle body 101 and the seat portion 122 of the nozzle needle 102 can be suppressed, the nozzle needle does not The shape of the sheet portion of the nozzle needle 102 is very complicated, and the shape of the sheet portion of the nozzle needle 102 cannot be easily processed. As a result, high processing accuracy is required, and the production cost of the Hall-type fuel injection nozzle becomes extremely high.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to easily process the first sheet portion of the nozzle body or the second sheet portion of the nozzle needle, to suppress the wear of the first sheet portion of the nozzle body or the second sheet portion of the nozzle needle, and It is an object of the present invention to provide a fuel injection nozzle capable of reducing manufacturing costs.

[0006]

According to the first aspect of the present invention, the first seat portion of the nozzle body is provided with an annular ridge line on which the second seat portion of the nozzle needle is seated, so that the first seat portion of the nozzle body is provided. Even when the sheet portion stress is generated in the seat portion, since the sheet portion stress is widely dispersed in the first sheet portion of the nozzle body having a larger volume than the second sheet portion of the nozzle needle, the maximum stress of the sheet portion is reduced by the conventional technology. It can be reduced in comparison.

As a result, the effect of suppressing the wear of the seat portion, which suppresses the wear of the first seat portion of the nozzle body or the second seat portion of the nozzle needle, can be improved as compared with the prior art. In addition, by providing an annular ridge line in the first sheet portion of the nozzle body, a sufficient angle difference is provided between the sheet surface on the upstream side and the sheet surface on the downstream side with respect to the ridge line of the first sheet portion of the nozzle body. Can be. Therefore, the shape of the first seat portion of the nozzle body can be easily processed, and the second seat portion of the nozzle needle is also a simple shape having a substantially conical surface shape, thereby reducing the manufacturing cost of the fuel injection nozzle. Can be.

According to the second aspect of the present invention, the first seat portion of the nozzle body has a two-stage substantially frustoconical seat surface, and the second seat portion of the nozzle needle has one or more stages. The seat surface has a substantially conical shape. According to the third aspect of the present invention, the angle of the sheet surface on the injection hole side of the nozzle body with respect to the ridge line of the first sheet portion is α, and the nozzle body is on the side opposite to the injection hole with respect to the ridge line of the first sheet portion of the nozzle body. When the sheet surface angle of the nozzle seat is β and γ is the sheet surface angle of the second seat portion of the nozzle needle, α <
β, 0 ° <γ−α ≦ 5 ° or 0 ° <β−γ ≦ 5 ° is satisfied. As a result, the larger the contact area of the nozzle body with the first sheet portion, that is, the smaller the seat angle difference, the more the effect of reducing the stress concentration of the seat portion can be improved.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [Structure of Embodiment] FIGS. 1 to 3 show an embodiment of the present invention.
FIG. 2 is a view showing a hall-type fuel injection nozzle used for a diesel engine. The other parts of the Hall-type fuel injection nozzle have a well-known structure, so that illustration and description are omitted.

The Hall type fuel injection nozzle of the present embodiment is
A cylinder head (not shown) and a piston are attached to each cylinder head of a direct injection diesel engine so that better ignition and combustion of fuel pressurized by a fuel injection pump (not shown) can be obtained. A fuel injection nozzle for an internal combustion engine that sprays into a combustion chamber (not shown) formed between the fuel injection nozzle and the combustion chamber (not shown). The Hall-type fuel injection nozzle includes a nozzle body 1 and a nozzle body 1.
And a nozzle needle 2 slidably housed therein.

The nozzle body 1 is formed in a substantially cylindrical shape. A nozzle holder (not shown) is connected to a rear end of the nozzle body 1 using a retaining nut (not shown) or the like. Inside the nozzle body 1, an axial hole 11 drilled in the axial direction of the nozzle body 1, and a sheet portion 1 formed so as to be connected to the tip of the axial hole 11.
2 and a suck hole 13 communicating with the seat portion 12 are provided. In addition, the axial direction hole 11, the sheet part 12,
The suck hole 13 is substantially coaxial.

The nozzle body 1 has a suck hole 1 inside.
A plurality of (in this example, two to eight) injection holes (in this example, two or more injection holes) are formed in the hemispherical rounded portion 14 where the nozzle hole 3 is formed so as to connect the suck hole 13 side and the combustion chamber side of the diesel engine. ) 15 are drilled on the same circumference. These injection holes 15 are provided in a fuel injection passage (opening diameter is, for example, φ0.1 to φ0.3) for spraying fuel into a combustion chamber of a diesel engine.
It is.

The seat portion 12 of the nozzle body 1 is a portion corresponding to the first seat portion of the present invention, and has a two-stage frustoconical seat surface. An annular ridgeline (valve seat, edge portion) 16 on which the tip of the nozzle needle 2 is seated or separated is formed on the seat portion 12. For this reason, a flat sheet surface 17 is provided on the injection hole 15 side (downstream in the fuel flow direction) of the ridgeline 16 of the seat portion 12, and the injection hole 15 is located closer to the injection hole 15 than the ridgeline 16 of the seat portion 12. On the other side (upstream side in the fuel flow direction), a flat sheet surface 18 is provided.

The nozzle needle 2 is formed in a substantially round bar shape, and is constantly urged in a direction to close the plurality of injection holes 15 by a coil spring or the like (urging means) (not shown) housed in the nozzle holder. . This nozzle needle 2
Has a cylindrical axial portion 21 and a simple conical seat portion 22, and has a predetermined clearance (fuel reservoir) 23 between the axial hole 11 and the axial portion 21 of the nozzle body 1. It is housed so that it can be moved back and forth freely. Although not shown, the rear end of the nozzle needle 2 is slidably held in the nozzle body 1.

As is well known, the clearance 23 is a fuel passage for passing fuel supplied through a path (not shown). Further, when the nozzle needle 2 is separated (lifted) from the ridgeline 16 of the nozzle body 1, a fuel passage from the clearance 23 to the plurality of injection holes 15 through the suck holes 13 (for example, a clearance of 0.25 mm)
０．３0.30 mm).

The seat portion 22 of the nozzle needle 2 is a portion corresponding to the second seat portion of the present invention, has a single-stage conical seat surface (conical surface), has no ridges (lines), and has a straight shape. The fuel passage can be blocked by bringing the seat portion 22 of the nozzle needle 2 into liquid-tight contact (seating) with the ridge line 16 of the nozzle body 1. In addition, the movement (lift) of the nozzle needle 2 in the valve opening direction causes the seat portion 22 to move.
Is released (lifted) from the ridge line 16 of the nozzle body 1, the fuel passage is opened, and the clearance 23
The fuel supplied from the side is passed to the plurality of injection holes 15.

Here, the ridge line 16 formed on the sheet portion 12 of the nozzle body 1 is aligned with the sheet portion 12 of the nozzle body 1.
The angle of the sheet surface 17 on the side of the injection hole 15 with respect to the ridge line 16 of the nozzle body 1 (for example, the angle around the point A of the central axis of the nozzle body 1) is α °, and the injection hole 15 is larger than the ridge line 16 of the sheet portion 12 of the nozzle body 1. The angle of the sheet surface 18 on the opposite side (eg, an angle centered on the point B of the central axis of the nozzle body 1) is β °, and the seat surface angle centered on the tip of the seat portion 22 of the nozzle needle 2 is γ. Then α ° <β
°, 0 ° <γ ° -α ° ≦ 5 ° or 0 ° <β ° -γ ° ≦
It is formed so as to satisfy the relationship of 5 °.

[Operation of Embodiment] Next, the operation of the Hall-type fuel injection nozzle of this embodiment will be briefly described with reference to FIGS.

When fuel pressurized to a high pressure from the fuel injection pump is supplied into a fuel hole (not shown) of the hole type fuel injection nozzle through the injection pipe, the axial end of the hole type fuel injection nozzle Clearance to the side (fuel pool) 2
3, and the supply pressure in the clearance 23 increases quickly.

When the supply pressure of the fuel in the clearance 23 becomes higher than the valve opening pressure determined by the urging force of the coil spring or the like, the nozzle needle 2 lifts up and separates from the ridge line 16 of the nozzle body 1 (seating). I do.
When the nozzle needle 2 is lifted, the fuel in the clearance 23 of the nozzle body 1 passes through the fuel passage between the seat portion 12 and the seat portion 22 and passes through the suck hole 13.
, And sprayed into the combustion chamber of the diesel engine from the plurality of injection holes 15 to start injection of high-pressure fuel.

After that, when the fuel pumping is completed, the fuel pressure in the Hall-type fuel injection nozzle is reduced, and the nozzle needle 2 is lowered (in a common rail system, when the valve is forcibly closed), the nozzle needle 2 is moved. The fuel injection ends when the seat body 12 of the nozzle body 1 is impacted and seated.
Therefore, in the conventional nozzle for preventing abrasion of the seat portion (STD: see FIG. 5), the nozzle needle 1
In the hall type fuel injection nozzle (nozzle for preventing abrasion of the seat portion) according to the present invention, the seat portion 122 having the maximum stress on the seat portion 122 side emerges on the seat portion 12 side of the nozzle body 1 (see FIG. 2). ). Here, in FIG. 2, a solid line on the data indicating the sheet part stress with respect to the sheet part position represents the sheet part stress of the nozzle bodies 1 and 101,
The dashed line represents the sheet stress of the nozzle needles 2 and 102.

In the product of the present invention, the sheet portion 22 of the nozzle needle 2 has no ridge line, the shape of the sheet portion is straight, and the annular ridge line 16 for the sheet with the sheet portion 22 of the nozzle needle 2 is formed by the nozzle body 1. Seat part 12
To the nozzle body 1
Of the seat portion 12. Therefore, the nozzle needle 2
Even if the seat portion 22 of the nozzle needle 2 seats (collides) with the seat portion 12 of the nozzle body 1 and a seat portion stress is generated, the nozzle body 1 having a larger volume than the seat portion 22 of the nozzle needle 2
The sheet portion stress can be dispersed over a wide range of the sheet portion 12.

As a result, the stress concentration relief function of the seat portion acts, and as shown in FIG. 2, the maximum stress of the seat portion is reduced as compared with the non-wear nozzle for the seat portion (STD: see FIG. 5). Wear of the seat portion 12 and the seat portion 22 of the nozzle needle 2 can be suppressed. Accordingly, the hole-type fuel injection nozzle (nozzle for preventing abrasion of the seat portion), which is a product of the present invention, can improve the effect of suppressing and promoting abrasion as compared with the nozzle for preventing abrasion of the seat portion (STD: see FIG. 5).

Further, the angle (upper angle) α ° of the sheet surface 17 on the injection hole 15 side with respect to the ridge line 16 of the sheet portion 12 of the nozzle body 1 and the ridge line 16 of the sheet portion 12 of the nozzle body 1
Since there is a sufficient difference (for example, about 4 °) between the angle (lower angle) β ° of the seat surface 18 on the opposite side to the injection hole 15 than
Edge line 16 of sheet portion 12 of nozzle body 1, sheet surface 1
The shapes 7 and 18 can be easily processed. Moreover, since the seat portion 22 of the nozzle needle 2 also has a simple shape (conical surface shape), the Hall-type fuel injection nozzle can be manufactured at very low cost.

Here, the optimum sheet angle difference considered to be effective for relieving the stress of the sheet portion of the nozzle body 1 is 0 ° <
γ ° -α ° ≦ 5 ° or 0 ° <β ° −γ ° ≦ 5 °
Is desired. It is not necessary to satisfy both at the same time, and either one of them is effective in relieving the stress of the sheet portion of the nozzle body 1.

[Experimental Results of the Embodiment] Next, the ridge line vertical angle (α, β) difference of the seat portion 12 of the nozzle body 1 of the hole type fuel injection nozzle of the present embodiment, that is, the seat angle difference (deg) is variously changed. Next, an experiment for investigating how the sheet stress of the nozzle body 1 changes will be described. In this experiment, the seat angle difference (deg)
Was varied and the stress in the sheet portion was investigated. The experimental results are shown in the graph of FIG.

As can be seen from the graph of FIG. 3, when the seat angle difference is larger than 0 ° and equal to or smaller than 5 °, the reduction in the stress at the seat portion (sheet surface pressure) is very remarkable. On the other hand, when the seat angle difference is> 5 °, the increase in the seat stress (seat surface pressure) is very moderate, and it is considered that the increase in the seat contact area is almost converged. The effect of suppressing the stress in the sheet portion with a difference> 5 ° cannot be expected so much.

Therefore, the smaller the difference between the ridge line vertical angles (α, β) of the seat portion 12 of the nozzle body 1 of the hole type fuel injection nozzle of the present embodiment, that is, the smaller the seat angle difference, the larger the contact area of the seat portion. It can be inferred that the larger the part contact area, the smaller the sheet part stress (sheet surface pressure) and the effect of suppressing the part stress concentration.

[Other Embodiments] In this embodiment, the seat portion 22 of the nozzle needle 2 has a simple conical surface shape. However, as shown in FIG.
If the nozzle needle 2 does not contact the sheet surface (particularly, the ridgeline 16) of the nozzle body 1, the nozzle needle 2 may have a multi-stage conical shape (conical shape and frustoconical shape). In this case, it is possible to reduce the pressure loss of the fuel by enlarging the fuel passage of the seat inlet 25, and to avoid the interference between the tip of the nozzle needle 2 and the crest 14 of the nozzle body 1. Very easy. Here, 0 ° <γ ° −α ° ≦
5 ° or 0 ° <β ° −γ ° ≦ 5 °, α ° <β
°, γ ° <δ °. Here, γ is the angle (deg) of the sheet outlet 26, and δ ° is the angle of the sheet inlet 25.

In this embodiment, the openings of the plurality of injection holes 15 are circular, but the openings of the plurality of injection holes 15 may be polygonal, oval, or elliptical. The number of the injection holes 15 may be any number as long as it is one or more. Further, in the present embodiment, the present invention is mounted on the cylinder head of the direct injection type diesel engine and the fuel is directly injected into the combustion chamber. It may be injected indoors.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a Hall-type fuel injection nozzle (Embodiment).

FIG. 2 is an explanatory diagram showing a state of occurrence of a seat stress with respect to a seat position of a hall-type fuel injection nozzle (embodiment).

FIG. 3 is a graph showing a relationship between a seat angle difference and a seat part stress (embodiment).

FIG. 4 is a sectional view showing a Hall-type fuel injection nozzle (another embodiment).

FIG. 5 is an explanatory diagram showing a state of occurrence of a stress in a seat portion with respect to a position of a seat portion of a nozzle for which a seat portion has not been worn (prior art).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Nozzle body 2 Nozzle needle 12 Nozzle body sheet part (first sheet part) 15 Injection hole (injection hole) 16 Ridge line 17 Seat surface 18 Seat surface 22 Sheet part of nozzle needle (Second sheet part)

Claims (3)

[Claims] An injection hole for injecting fuel, and a nozzle body having a first seat portion upstream of the injection hole,
A nozzle needle displaceably slidably in the nozzle body and having a nozzle seat having a substantially conical second seat portion seated on the first seat portion of the nozzle body. A fuel injection nozzle, wherein an annular ridgeline on which the second seat portion of the nozzle needle is seated is provided in the seat portion. 2. The fuel injection nozzle according to claim 1, wherein the first seat portion of the nozzle body is a two-stage substantially frustoconical seat surface, and the second seat portion of the nozzle needle is one stage or A fuel injection nozzle having a substantially conical seat surface having two or more stages. 3. The fuel injection nozzle according to claim 2, wherein an angle of a sheet surface on an injection hole side with respect to a ridge line of the first sheet portion is α, and the seat surface angle is opposite to a ridge line of the first sheet portion with respect to the injection hole. When β is the sheet surface angle of the second side and γ is the sheet surface angle of the second sheet portion, the relationship of α <β, 0 ° <γ-α ≦ 5 ° or 0 ° <β-γ ≦ 5 ° is satisfied. A fuel injection nozzle characterized by satisfying.