JP2002130086A - Two-stage injection fuel injection valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a two-stage injection fuel injection valve capable of forming atomization for premix combustion performance and diffusion combustion performance by use of a single fuel injection valve to minimize the mounting space around a cylinder head, freely changing the injection rate to facilitate the control, and reducing the cost. SOLUTION: Attentions are paid in this fuel injection valve to change the atomization shape depending on the lift position of a needle valve 7, changing an oil passage between initial injection of first stage and main injection of second stage to change the injection rate, and changing the oil passage volume so that the injection pressure of the main injection of second stage can be raised depending on the lift position of the needle valve 7. The oil passage 9 extending to an injection part 10 is divided to a first oil passage 9A and a second oil passage 9B, and the first oil passage 9A and the second oil passage 9B can be switched to be combined or separated according to the lift of the needle valve 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-stage injection fuel injection valve, and more particularly to a two-stage injection fuel injection valve for injecting fuel into a combustion chamber of a diesel engine or the like as a two-stage spray having different forms. Things.

[0002]

2. Description of the Related Art Conventionally, studies have been made to reduce emissions from diesel engines. However, nitrogen oxides (NOx) emitted after combustion greatly depend on the equivalence ratio of the air-fuel mixture. Initial injection for lean premixed combustion, in which injection is performed near the injection hole before compression of the piston to perform mixing with air in advance, and main injection for diffusion combustion, which is injected with a large penetration in a ignitable compressed state Research cases have been reported in which nitrogen oxides can be reduced by combustion based on the injection of the formula. However, in order to obtain the initial injection for lean premixed combustion and the main injection for diffusion combustion, for example, three fuel injection valves are required. That is, there are two side injectors for lean premixed combustion facing the left and right portions of the combustion chamber in the cylinder, and one center injector for diffusion combustion facing the central portion. Can be controlled independently. Therefore, in order to actually mount such a fuel injection valve on an engine, it is necessary to devise an installation space around the cylinder head, and control for switching the respective sprays by the three fuel injection valves. There are problems such as complicated circuits and piping.

[0003] Japanese Patent Application Laid-Open Nos. 4-41973 and 10-47206 disclose a technique for varying the injection amount or a technique for two-stage injection.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has been made in consideration of the above circumstances. Accordingly, it is possible to form a spray for a premix combustion function and a diffusion combustion function by a single fuel injection valve. It is an object to provide a stage injection fuel injection valve.

Another object of the present invention is to provide a two-stage injection fuel injection valve which requires a small space for mounting around a cylinder head, is easy to control, and can reduce the cost.

Another object of the present invention is to provide a two-stage injection fuel injection valve capable of forming sprays having different shapes and forms from each other.

Another object of the present invention is to provide a two-stage injection fuel injection valve capable of forming a two-stage spray by a lift position of a needle valve for fuel injection.

According to the present invention, the first-stage initial injection forms a spray in which a uniform flow rate is produced in the radial direction so as not to hit the inner wall of the cylinder of the engine. An object of the present invention is to provide a two-stage injection fuel injection valve capable of freely changing the injection rate by changing the spray shape and forming a spray having a penetrating force with the initial injection of the eye.

[0009]

That is, according to the present invention, the shape of the spray is made different depending on the lift position of the needle valve. The first stage initial injection and the second stage main injection change the oil passage to change the injection rate. And focus on changing the oil passage volume so that the injection pressure of the second stage main injection can be increased depending on the lift position of the needle valve, which leads to the fuel oil passage. It has a nozzle body with an injection section, and a needle valve that seats on the nozzle body and opens and closes the injection section. Fuel can be injected in two stages from the injection section with the lift of the needle valve. A two-stage injection fuel injection valve, wherein the oil passage leading to the injection unit is divided into a first oil passage and a second oil passage, and these oil passages are lifted by the needle valve. Which is the oil passage and two-stage injection fuel injection valve, characterized in that the second oil passage and a switchable confluence or to separate.

When the needle valve is at the initial lift position, the fuel from the first oil passage and the second oil passage is merged and collided and injected, and when the needle valve is at the high lift position of the needle valve. Can inject the fuel only from the first oil passage.

When the first oil passage and the second oil passage are both opened, a spray having a relatively large injection rate is formed, and when only the first oil passage is opened, the injection is performed. Sprays with relatively low rates can be formed.

The second oil passage can be closed at a branch point or a junction of the first oil passage and the second oil passage.

A lift control means capable of driving the needle valve is provided, a first-stage piston receiving a drive pressure from the lift control means with a larger pressure-receiving area, and a second-stage piston having a smaller pressure-receiving area than the first-stage piston. A stage piston,
And the second stage piston can be used as the needle valve.

[0014] The needle valve initial lift position regulating member and the needle valve high lift position regulating member may be provided.

In the two-stage injection fuel injection valve according to the present invention, the single fuel injection valve opens and closes so as to diverge or merge the oil passage depending on the lift position of the needle valve. Since the injection rate is changed by changing the oil path of the second stage main injection, the shapes of the first stage initial spray and the second stage main spray are different from each other, and the spray according to the operating state of the piston To improve combustion characteristics and reduce nitrogen oxides. Therefore, it is not necessary to attach a plurality of fuel injection valves to the cylinder head of the engine, so that the installation space can be saved and the control circuit can be prevented from becoming complicated.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A two-stage fuel injection valve 1 according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view of the two-stage injection fuel injection valve 1 in a non-injection state. The two-stage injection fuel injection valve 1 includes a nozzle holder 2, a nozzle body 3, a retaining nut 4,
Lift control means 5, first stage piston 6 (initial lift position regulating member), needle valve 7 (second stage piston),
Having.

The nozzle holder 2 is formed with a fuel supply port 8 for high-pressure fuel, and communicates with the fuel supply port 8 from the nozzle holder 2 to the tip of the nozzle body 3.
An oil passage 9 for fuel is formed.

The nozzle body 3 includes a retaining nut 4
This is fixed to the nozzle holder 2 to form the injection unit 10 facing the tip of the oil passage 9.

The lift control means 5 is constituted by an arbitrary member such as a piezo element, a giant magnetostrictive element, an electromagnetic valve or a hydraulic pressure amplifying device, and is driven by a drive control circuit 11. The tip of the working pressure chamber 12 faces the working pressure chamber 12, and the first stage piston 6 and the needle valve 7 can be driven by increasing the pressure in the working pressure chamber 12.

The first-stage piston 6 is slidably housed inside the nozzle holder 2 and is provided with a needle valve through a spring seat 14 (high-lift-position regulating member) by a first spring 13 for rattling. This is urged in seven directions (downward in the figure).

The needle valve 7 is a poppet type (open-out type) valve body, and is slidably engaged with the first stage piston 6 via the spring seat 14 integrated therewith. The return second spring 15 seated on the spring seat 14 urges the spring in the seat direction (upward in the figure).

The first stage piston 6 has a slight gap (initial lift amount L1) between its tip 6A and the stopper 3A of the nozzle body 3. The spring seat 14 has a slight gap (high lift amount L2) between its tip portion 14A and the stopper portion 3A of the nozzle body 3.

The first stage piston 6 receives the driving pressure from the lift control means 5 in the working hydraulic chamber 12 with a larger pressure receiving area, and the needle valve 7 has a smaller pressure receiving area than the first stage piston 6.

The needle valve 7 has an upstream axial through passage 1
6 and a downstream axial passage 17, and a central through passage 18 communicating the upstream axial passage 16 and the downstream axial passage 17. The poppet portion 7A located at the tip of the needle valve 7 has an upstream axial passage 1
6. After the downstream axial passage 17 and the central through passage 18 are formed, they are closed with blind plugs (plugs). The poppet portion 7A is seated on the seat portion 3B of the nozzle body 3 in the ejection portion 10. I have.

An oil sump chamber 19 is formed in the middle of the oil passage 9, and a part of the fuel sump chamber 19 is connected to a branch point 20.
(FIG. 2) and the downstream axial through-passage 1 facing the injection unit 10
The outlet of 7 is a junction 21 (FIG. 3). However,
In the state shown in FIG. 1, since the fuel reservoir 19 is disconnected from the upstream axial passage 16 by the outer peripheral surface of the needle valve 7, the first oil passage 9 </ b> A and the second oil passage 9
B is in a cutoff state. The oil passage 9 can be divided into a first oil passage 9A and a second oil passage 9B at a branch point 20, and can be merged at a junction 21. That is, the first
The oil passage 9A extends from the branch point 20 (fuel pool 19) to the junction 21 via the upstream axial passage 16, the central passage 18 and the downstream axial passage 17. Second oil passage 9
B passes from the branch point 20 to the junction 21 through between the nozzle body 3 and the outer periphery of the needle valve 7.

The operation of the two-stage injection fuel injection valve 1 having such a configuration will be described with reference to FIGS. FIG.
2 is a cross-sectional view of the needle valve 7 at the seat position, FIG. 3 is a cross-sectional view of the initial lift position, FIG. 3 is an enlarged cross-sectional view of a main part of the injection unit 10 at the initial lift position, and FIG. 5 and FIG. 5 show the injection unit 10 at the high lift position.
Are enlarged cross-sectional views of main parts of FIG. As shown in FIG. 1, when the needle valve 7 is seated on the nozzle body 3, the fuel reservoir 19 and the upstream axial through passage 16 in the oil passage 9 are not in communication with each other. In addition, since the poppet portion 7A of the needle valve 7 is seated on the seat portion 3B of the nozzle body 3 in the ejection portion 10, it is in a non-ejection state.

As shown in FIG. 2, when the lift control means 5 is driven by a drive signal from the drive control circuit 11 to increase the pressure in the working pressure chamber 12, the lift control means 5 resists the urging force of the second spring 15. Then, the first-stage piston 6 and the needle valve 7 are slightly lifted downward in the drawing, and the distal end portion 6A of the first-stage piston 6 as the initial lift position regulating member comes into contact with the stopper portion 3A of the nozzle body 3. Further movement is prevented (initial lift amount L1). In addition, since the pressure in the working pressure chamber 12 is received in a larger area including the pressure receiving areas of the first stage piston 6 and the needle valve 7,
The operation is started relatively slowly as the initial lift. As described above, the first-stage lift (initial lift) employs the lift control means 5 using a piezo element or the like, and an arbitrary initial lift position can be obtained by precise control.

At this initial lift position, as shown in an enlarged view in FIG. 3, the first oil passage 9A and the second oil passage 9B of the oil passage 9 merge at the junction 21 of the injection unit 10, The fuel injected from the downstream axial passage 17 and the fuel injected from the second oil passage 9B collide with each other and are relatively mixed, and the injection hole between the poppet 7A and the seat 3B is formed. Injected from 10. Therefore, as shown in FIG. 2 in particular, the shape of the spray is a spray having a large hydraulic flow rate that does not reach the inner wall surface of the cylinder, and has a small so-called penetration, and has a relatively large injection rate and a lean injection rate. Injection suitable for premix combustion.

When pressure is further applied to the working pressure chamber 12 from the initial lift state shown in FIGS. 2 and 3, the first stage piston 6 remains stopped with respect to the nozzle body 3, and only the needle valve 7 receives a smaller pressure. Since the pressure is received by the area, the lift is performed at a higher speed than at the time of the initial lift, and the lift is further lifted together with the spring seat 14 as a high lift position restricting member so that the tip portion 14A comes into contact with the stopper portion 3A of the nozzle body 3, and Movement is prevented (high lift L
2).

That is, in the high lift state shown in FIG.
At the branch point 20, the oil passage 9 (the second oil passage 9B) is closed by the outer peripheral surface of the needle valve 7, is separated from the first oil passage 9A, and fuel is injected only from the first oil passage 9A. It reaches the part 10. Therefore, as shown in an enlarged manner in FIG. 5, a spray having a large penetration and a relatively small injection rate is formed only from the first oil passage 9A without supplying the fuel from the second oil passage 9B. Thus, a spray suitable for diffusion combustion is injected. As described above, the second-stage main lift can open the injection unit 10 at the high lift position and spray the spray having the penetrating power.

FIG. 6 is a graph showing the relationship between the lift rate of the needle valve 7 and the injection rate. As shown by the dotted line, in the conventional general fuel injection valve, the injection rate is low in the initial lift state. As shown by the solid line, in the two-stage injection fuel injection valve 1 according to the present invention, it is possible to obtain a higher injection rate and to realize fuel injection capable of improving the combustion characteristics in the combustion chamber. Therefore, conventionally, the mixed injection combustion and the hydrocarbon (CH) of the side injection by the two side injectors were reduced and the hydrocarbon (CH) was reduced by relying on the offset spray that does not apply the spray to the inner wall surface of the cylinder. During mass production, there is a concern that there is a variation in the control of equal injection and simultaneous injection by the two side injectors, but the single two-stage injection fuel injection valve 1 according to the present invention solves such a problem.

In addition, conventionally, there are two types of fuel injection valves, ie, two fuel injection valves for side injection lean premix combustion.
And one fuel injection valve for center injection diffusion combustion, which required a total of three fuel injection valves,
This makes it possible to simplify the engine layout and reduce the cost. Furthermore, the injection rate of the first stage initial injection is increased as much as possible, and the conventional injection hole is the same, but the groove area (width and radius) of the needle valve 7, that is, the upstream axial through passage 16 By uniformly selecting the cross-sectional area of the downstream axial through-passage 17, the central through-passage 18, the second oil passage 9B, and the like, and by increasing and decreasing the injection rate, uniform injection around the inside of the engine cylinder is achieved. Can be possible. In the second-stage main injection, the combination of the minimum injection holes can be made possible by designing the downstream axial through-passage 17 with an arbitrary number or diameter.

It should be noted that the injection amount and injection timing of the initial lift of the first stage and the high lift of the second stage can be selected by an arbitrary lift position. The timing can be freely changed. Also, the diameter and number of the injection holes as the two-stage injection and the injection direction can be variously combined.

[0034]

As described above, according to the present invention, the first oil passage and the second oil passage can be switched so as to join or separate with the lift of the needle valve. Spray for function and diffusion combustion function can be formed by a single fuel injection valve, improving combustion characteristics,
This can contribute to simplification around the cylinder head and further reduction in cost.

[Brief description of the drawings]

FIG. 1 is a sectional view of a two-stage injection fuel injection valve 1 according to an embodiment of the present invention in a non-injection state.

FIG. 2 is a cross-sectional view of the same at an initial lift position.

FIG. 3 is an enlarged sectional view of a main part of the injection unit 10 at an initial lift position.

FIG. 4 is a sectional view of the same at a high lift position.

FIG. 5 is an enlarged cross-sectional view of a main part of the injection unit 10 at the high lift position.

FIG. 6 is a graph showing the relationship between the lift rate of the needle valve 7 and the injection rate.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Two-stage injection fuel injection valve (Embodiment) 2 Nozzle holder 3 Nozzle body 3A Stopper part of nozzle body 3 3B Seat part of nozzle body 3 4 Retaining nut 5 Lift control means 6 First stage piston (Initial lift position regulation 6A Tip part of first stage piston 6 7 Needle valve (second stage piston) 7A Poppet part of needle valve 7 (plug, blind plug) 8 Fuel supply port 9 Fuel oil passage 9A First oil passage 9 Oil passage 9B Second oil passage of oil passage 9 10 Injection unit 11 Drive control circuit 12 Working pressure chamber 13 First spring for rattling 14 Spring seat (high lift position regulating member) 14A Tip end of spring seat 14 15 Second spring for return 16 Upstream axial through passage 17 Downstream axial through passage 18 Central through passage 19 Fuel reservoir 20 minutes Point 21 Junction point L1 Initial lift amount between tip 6A of first stage piston 6 and stopper 3A of nozzle body 3 L2 Between tip 14A of spring seat 14 and stopper 3A of nozzle body 3 High lift

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02M 61/04 F02M 61/04 H 61/08 61/08 B H F term (Reference) 3G066 AA07 AB02 AD12 BA03 BA04 BA13 BA61 BA67 CC01 CC06T CC06U CC08T CC08U CC18 CC40 CC48 CC66 CE13 CE27 DA11 DA12

Claims (6)

[Claims] 1. A nozzle body having an injection portion connected to an oil passage for fuel, and a needle valve seated on the nozzle body and opening and closing the injection portion. A two-stage injection fuel injection valve capable of injecting fuel in a two-stage manner from an injection unit, wherein the oil passage leading to the injection unit is divided into a first oil passage and a second oil passage, and the needle valve is provided. Characterized in that the first and second oil passages can be switched to join or separate with the lift of the two-stage injection fuel injection valve. 2. When the needle valve is at an initial lift position, the fuel from the first oil passage and the second oil passage is merged and collided and injected, and the needle valve is at a high lift position of the needle valve. Sometimes, the first
2. The two-stage injection fuel injection valve according to claim 1, wherein said fuel is injected only from said oil passage. 3. When both the first oil passage and the second oil passage are opened, a spray having a relatively large injection rate is formed, and when only the first oil passage is opened. 2. The two-stage injection fuel injection valve according to claim 1, wherein the injection rate forms a relatively small spray. 4. The two-stage injection fuel according to claim 1, wherein the second oil passage can be closed at a branch point or a junction of the first oil passage and the second oil passage. Injection valve. 5. A lift control means capable of driving the needle valve, a first stage piston receiving a drive pressure from the lift control means with a larger pressure receiving area, and a pressure receiving area smaller than the first stage piston. The two-stage injection fuel injection valve according to claim 1, further comprising a second-stage piston, wherein the second-stage piston is the needle valve. 6. The two-stage injection fuel injection valve according to claim 1, further comprising an initial lift position restricting member for the needle valve and a high lift position restricting member for the needle valve.