JPH089424Y2 - Fuel injection nozzle with dodge plunger - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a fuel injection nozzle having a dodge plunger.

[Prior Art] As a conventional fuel injection nozzle of this type, for example, there is one described in Japanese Utility Model Laid-Open No. 1-71171. The fuel injection nozzle described in this publication is constructed as schematically shown in FIG.

That is, the needle valve b is arranged on the lower end side of the nozzle spring a, and the dodge plunger c is arranged on the upper end side thereof. The needle valve b and the dodge plunger c are biased in opposite directions by the nozzle spring a, and are seated on the first valve seat d and the second valve seat e, respectively. On the other hand, the needle valve b
The fuel pumped through the first passage f lifts the nozzle spring a against the biasing force of the nozzle spring a, and the dodge plunger c is pumped by the fuel pumped through the second passage g. It is designed to be lifted against the biasing force of the spring a.

Here, the diameter of the needle valve b is D _N , the seating diameter is d _N ,
If the diameter of the dodge plunger c is D _D and the seating diameter is d _D ,
Pressure receiving area when the needle valve b is seated and lifted
The pressure receiving areas S _D1 and S _D2 of S _N1 and S _N2 and of the dodge plunger c when seated and lifted are as follows.

S _N1 = π ・ (D _N ² −d _N ² ) S _N2 = π ・ D _N ² S _D1 = π ・ d _D ² S _D2 = π ・ D _D ² These pressure receiving areas are S _D1 <S _N1 < Each size is determined so as to satisfy S _N2 <S _D2 .

Therefore, in the fuel injection nozzle having the above-described structure, as shown in FIG. 3 (A), the needle valve b and the dodge plunger c are seated when the fuel is not being pumped, but the fuel is pumped and the When the pressure reaches a predetermined pressure, since S _D1 <S _N1 , the needle valve b first lifts as shown in FIG. 3 (B). When the fuel pressure further rises, the dodge plunger c is lifted as shown in FIG. 3 (C). Then, the biasing force of the nozzle spring a increases, so that the needle valve b is seated. Initial fuel injection is performed before this seating. When the fuel pressure further rises, the needle valve b lifts again against the biasing force of the nozzle spring a, and the main injection is performed.

After that, when the pressure feeding of the fuel ends and the pressure decreases, since S _N2 <S _D2 , the needle valve b is first seated and the state shown in FIG. 3 (C) is obtained. Next, dodge plunger c
Is seated and returns to the original state shown in FIG.

As described above, the fuel injection nozzle with the dodge plunger can inject fuel into the initial fuel injection and the main fuel injection separately, and the nozzle spring a is compressed by the dodge plunger c when the needle valve 2 is closed. The valve closing pressure can be increased because
As a result, it is possible to improve the fuel injection shortage.

[Problems to be Solved by the Invention] However, although the conventional fuel injection nozzle with a dodge plunger has an effect that fuel can be injected separately into initial fuel injection and main fuel injection, Had a problem that it could not be improved as expected.

That is, the dodge plunger c is arranged on the upper end side of the fuel injection nozzle, and the needle valve b is arranged on the lower end side. Moreover, the fuel inlet h is arranged on the upper end side of the fuel injection nozzle. As a result, the length of the second passage g is significantly shorter than the length of the first passage f. When the length of the second passage g is significantly shorter than the length of the first passage f, the fuel pressure decreases rapidly on the side of the dodge plunger c and slows on the side of the needle valve b at the end of the pressure feeding of the fuel. For this reason, the dodge plunger c may be seated almost at the same time as the needle valve b is seated, or the dodge plunger c may start seated while the needle valve b is seated. Therefore, the nozzle spring a extends due to the seating or movement of the dodge plunger c, and the valve closing pressure of the needle valve b decreases. Therefore, the fuel injection could not be improved to the extent expected.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a fuel injection nozzle with a dodge plunger that can improve shortage of fuel injection.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention provides a needle valve and a dodge plunger by means of a nozzle spring arranged between them to provide a first valve seat and a second valve seat. Each of them is seated, and the needle valve is lifted against the nozzle spring by the fuel pumped through the first passage, and the dodge plunger is resisted by the fuel pumped through the second passage. And the needle valve is pushed by the fuel, and the pressure receiving areas of the seated valve and the lifted valve are S _N1 and S _N2 , respectively, and the pressure receiving area of the dodge plunger pressed by the fuel is the seated area. when respectively with the S _D1, S _D2 between time _{lift, S D1 <S N1 <S} N2 < the fuel injection nozzle with Dodge plunger satisfying S _D2, the second passage, As the length of the longer, it is characterized in that it has formed a plurality of holes through sequentially communicated.

In this case, the length of the second passage is appropriately determined according to the difference between the pressure receiving areas of the needle valve and the dodge plunger when seated, and preferably the first passage.
Equalized to the length of the passage.

[Operation] At the end of the pressure feeding of the fuel, the pressure drop of the fuel on the side of the dodge plunger is delayed by the length of the second passage, and the seating time of the dodge plunger is delayed accordingly. In other words, the seating timing of the needle valve becomes relatively early, which prevents the dodge plunger from seating at about the same time as seating of the needle valve or starting seating movement during the seating movement of the needle valve.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 shows an embodiment of the present invention. This fuel injection nozzle is fixed to a nozzle holder 1 having a cylindrical shape, and a nut 2 on a lower end surface of the nozzle holder 1 via a spacer 3. The nozzle portion 4 and the plug 6 fixed to the upper end surface of the nozzle holder 1 by a nut 5 are provided.

Inside the nozzle holder 1, a cylinder member 7 is inserted on the upper end side and fixed by bolts 8. A pressure oil introduction chamber 9 is formed between the contact surfaces of the cylinder member 7 and the bolt 8. The pressure oil introduction chamber 9 includes the inner peripheral surface of the nozzle holder 1, the lower end surface of the plug 6, and the bolt 8
The closed space 10 defined by the upper end surface of the bolt 8 is communicated with the bolt 8 through a through hole 8a. Further, a dodge plunger 11 is slidably provided inside the cylinder member 7. The dodge plunger 11 is adapted to be seated / separated from a valve seat (second valve seat) 7a formed inside the upper end side of the cylinder member 7.

A nozzle spring 12 is inserted and arranged inside the lower end of the nozzle holder 1. The nozzle spring 12 allows the dodge plunger 11 to be seated on the valve seat 7a. The inner space of the nozzle holder 1 in which the nozzle spring 12 is inserted is connected to a fuel tank (not shown) via a spill passage 13 formed over the nozzle holder 1 and the plug 6.
It is connected to the.

The nozzle portion 4 has a nozzle body 41 and a needle valve 42 slidably provided therein as main components. Inside the lower end of the nozzle body 41, the valve seat (first
A valve seat) 43 is formed, and further below that, an injection hole 44 that opens to the lower end surface of the nozzle body is formed. on the other hand,
The needle valve 42 is biased downward by the nozzle spring 12 and seated on the valve seat 43. The injection hole 44 is closed by sitting on the valve seat 43, and opened by lifting from the valve seat 43.

The needle valve 42 and the dodge plunger 11 are lifted by the fuel pumped from a fuel injection pump (not shown).

That is, a fuel inlet 61 connected to a fuel injection pump via a high-pressure pipe (not shown) is formed on the upper end surface of the plug 6, and the fuel inlet 61 extends from the fuel inlet 61 to the nozzle holder 1 inside. A passage 62 is formed which extends to the recess 14 formed between the contact surfaces with the plug 6. Further, a first passage 15 extends downward from the recess 14, and the first passage 15 penetrates the nozzle holder 1 and the spacer 3 and forms a fuel reservoir 45 formed in the nozzle body 41.
Has reached. The needle valve 42 is lifted when the pressure of the fuel pumped from the fuel inlet 61 to the fuel reservoir 45 through the passage 62 and the first passage 15 reaches a predetermined valve opening pressure.

In addition, the plug 6 is provided with a second passage 16 that communicates the recess 14 with the closed space 10 and further with the pressure oil introduction chamber 9. When the fuel pressure-fed to the pressure oil introduction chamber 9 through the second passage 16 reaches a predetermined valve opening pressure, the dodge plunger
11 lifts.

Here, the pressure receiving areas of the needle valve 42 when seated and when lifted are S _N1 and S _N2 respectively, and the dodge plunger is
The pressure-receiving areas of 11 when seated and lifted are S _D1 , S
_{If it is D2} , S _D1 <S _N1 <S _N2 <S _D2 is set.

The second passage 16 has a hole 16a extending from the recess 14 toward the upper end of the plug 6, and a hole extending downward from the upper end of the hole 16a and opening at the lower end surface of the plug 6 facing the closed space 10. It consists of 16b and. These two holes 16a, 1
The total length of 6b is set to satisfy the following relationship.

That is, the respective pressures of the fuel pool 44 and the pressure oil introduction chamber 9 at the end of the pressure feed of the fuel from the fuel injection pump are
If P ₁ and P ₂ (P ₁ ≧ P ₂ if the length of the second passage 16 is equal to or less than the length of the first passage 15), the pressing force of the fuel against the needle valve 42 is P ₁ It becomes S _N2 , and the pressing force against the dodge plunger 11 becomes P ₂ · S _D2 . These pressing force P
As _{1 · S N2, P 2 ·} S D2 satisfies _{P 1 · S N2 <P 2} · S D2, the total length of the second passage 16 is defined.

In the fuel injection nozzle having the above-described structure, the needle valve 42 is lifted by the fuel that is pressure-fed to the fuel reservoir 45 through the first passage 14, while it is pressure-fed to the pressure oil introduction chamber 9 through the second passage 15. Dodge plunger by fuel
11 is lifted.

At this time, since S _D1 <S _N1 <S _N2 <S _D2 is set, when the pressure feeding of the fuel is started, the needle valve 42 is first lifted and the initial fuel injection is performed from the injection hole 44. After that, when the dodge plunger 11 is lifted, the needle valve 42 moves to the valve seat.
Seat 43 and finish the initial fuel injection. After that, the needle valve 42 is lifted again, and the main fuel injection is performed.

When the pressure feeding of the fuel is completed and the pressure of the fuel is reduced, the needle valve 42 is seated on the valve seat 43, the dodge plunger 11 is seated on the valve seat 7a, and the fuel injection is completed.

Here, if the length of the second passage 16 is significantly shorter than the length of the first passage 15, the pressure drop in the pressure oil introduction chamber 9 due to the completion of the pressure feeding becomes faster than the pressure drop in the fuel pool 45. As a result,
Although the pressure receiving area S _N2 when the needle valve 42 is lifted and the pressure receiving area S _D2 when the dodge plunger 11 is lifted are set so that S _N2 <S _D2 , the dodge plunger 11 is connected to the needle valve 42. Seated at about the same time or needle valve
There is a risk that the seat will start to move while the seat is moving.

In this respect, in the present invention, the second passage 16 is provided with a plurality of holes.
Since the length of the second passage 16 is lengthened by the construction of 16a and 16b, it is possible to delay the pressure decrease timing of the pressure oil introduction chamber 9. Moreover, since the length of the second passage 16 is determined so that P ₁ · S _N2 <P ₂ · S _D2 , the seating timing of the dodge plunger 11 can be delayed from the seating timing of the needle valve 42. Therefore, when the needle valve 42 is seated, the nozzle spring 12 is in a state of being compressed by the dodge plunger 11, and the needle valve 42 is seated by the nozzle spring 12 that is compressed and has a large biasing force. Therefore, it is possible to improve the fuel injection shortage.

In particular, in this embodiment, since the length of the second passage 16 is set to be substantially the same as the length of the first passage 15, the seating timing of the dodge plunger 11 is surely delayed from the seating timing of the needle valve 42. The dodge plunger 11 remains compressed for some time after the needle valve 42 is seated. Therefore, the needle valve 42 is continuously pushed strongly by the nozzle spring 12 even after it is seated. Therefore,
It is possible to prevent a so-called jump in which the needle valve 42 is seated on the valve seat 43 and then lifts again, so that it is possible to prevent the phenomenon of the fuel drooping.

The present invention is not limited to the above-described embodiments, but can be modified as appropriate without departing from the spirit of the invention.

For example, although one end of the second passage 16 is communicated with the recess 14 in the above-described embodiment, it may be communicated with the fuel inlet 61 as in the embodiment shown in FIG. That is, the third
In the embodiment shown in the drawing, the second passage 17 is provided with a hole 17a extending downward from the fuel inlet 61, a hole 17b extending upward from a lower end portion of the hole 17a, and a closed space 10 extending from an upper end portion of the 17b. And a hole 17c extending to the lower end surface of the plug 6 which faces.

In addition, in this embodiment, the first passage 15 includes the passage 62. Therefore, it is desirable that the second passage 17 has a length equal to the total length of the first passage 15 and the passage 62.

The number of holes forming the second passage may be four or more.

[Advantages of the Invention] As described above, according to the fuel injection nozzle with a dodge plunger of the present invention, the second passage for pressure-feeding the fuel to the dodge plunger side is formed by a plurality of holes that are successively communicated with each other. , Because I increased the length,
It is possible to prevent the dodge plunger from sitting at almost the same time as the needle valve, or to start the seating movement during the seating movement of the needle valve. The effect that the valve jump can be prevented can be obtained.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of the present invention, FIG. 2 is a vertical sectional view showing an essential part of another embodiment of the present invention, and FIG. 3 is a schematic view of a conventional fuel injection nozzle with a dodge plunger. FIG. 3 (A) is a view showing a configuration, in which both the needle valve and the dodge plunger are seated, and FIG. 3 (B).
Shows a state in which the needle valve is lifted and the dodge plunger is seated, FIG. 3 (C) is a diagram in which the needle valve is seated and the dodge plunger is lifted, and FIG. 3 (D) is a needle valve It is a figure which shows the state which both the Dodge plunger lifted. 1 ... Nozzle holder, 4 ... Nozzle part, 6 ... Plug, 7a ... Valve seat (second valve seat), 9 ... Pressure oil introduction chamber, 11 ... Dodge plunger, 12 ... Nozzle spring, 15 ... First passage, 16 ... 2nd passage, 16
a, 16b ... hole, 17 ... second passage, 17a, 17b, 17c ... hole, 42 ... needle valve, 43 ... valve seat (first valve seat).

Claims (1)

[Scope of utility model registration request] 1. A needle valve and a dodge plunger are respectively seated on a first valve seat and a second valve seat by means of a nozzle spring arranged between them, and by the fuel pumped through a first passage, A needle valve is lifted against the nozzle spring, fuel is forced through the second passage to lift the dodge plunger against the nozzle spring, and the needle valve is pressed by the fuel. The areas are S _N1 and S _N2 for seating and lifting, respectively, and the pressure receiving areas where the dodge plunger is pressed by the fuel are respectively for seating and lifting.
When the _{S D1, S D2, S D1} <S N1 <S N2 < The fuel injection nozzle with Dodge plunger satisfying S _D2, the second passage, such that its length becomes longer, a plurality of through successively communicated A fuel injection nozzle with a dodge plunger, which is formed by a hole.