JPS62298659A - Fuel injection nozzle of direct injection type diesel engine - Google Patents

Abstract

PURPOSE:To decrease the amount of fuel injection at the initial period of combustion with the fuel kept in properly mixed condition with the air, by furnishing a nozzle body with a plurality of jets in positions dislocated in circumferential direction from the lift direction of a needle valve, and putting the jets one after another in communication with the fuel supply passage. CONSTITUTION:When a needle valve 6 is lifted, No.1 and No.3 jets 5a, 5c at the foremost of a sack part 4 are put in communication with a fuel supply passage 2 via an injection passage 9, while No.2 and No.4 jets 5b, 5d at the tail of the sack part 4 are shut from communication by a seal 10. Accordingly a small amount of fuel is injected from No.1 and No.3 jets 5a, 5c, and put in pre-mixed combustion. If the needle valve 6 is further lifted, the No.2 and No.4 jets 5b, 5d are put in communication with the fuel supply passage 2 via the injection passage 9, while the No.1 and No.3 jets 5a, 5c are shut from communication by the seal 10. Thus a greater amount of fuel is injection from No.2 and No.4 jets 5b, 5d to be put in diffused combustion.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a fuel nozzle for a direct injection diesel engine, which has a plurality of nozzle holes at 1q, and from each of the nozzle holes. This relates to a fuel that does not have a time difference in j&l tFJ.

(Prior Art) Conventionally, as a fuel injection tA device for a direct injection diesel engine, for example, as disclosed in Japanese Utility Model Application Publication No. 60-8468, each cylinder of the engine is equipped with a pyrower 1 for injection and for primary control. Two fuel injection nozzles are arranged, the pilot injection nozzle is connected to the fuel injection pump via a short fuel supply pipe, and the main injection nozzle is connected to the fuel injection pump via a long fuel supply pipe. Due to the time difference between the pressure waves propagating through fuel supply pipes of different lengths, the timing of fuel injection from the pilot injection nozzle and the timing of fuel injection from the main injection nozzle are shifted back and forth, and pilot injection ( By injecting fuel only from the nozzle for (g), the amount of fuel injected at the initial stage of combustion is reduced, premix combustion is suppressed, and the generation of noise and nitrogen oxide is suppressed. It is known that this was done.

(Problem to be solved by the invention) However, in such a fuel injection device, two fuel supply pipes are branched from the same fuel injection pump, and pressure waves between the two fuel supply pipes are complicated. Therefore, it is extremely difficult to accurately set the fuel injection timing of the pilot injection nozzle and the main injection nozzle.

Furthermore, since two fuel injection nozzles are arranged in each cylinder, the fuel injection nozzle cannot be arranged in the center of the cylinder, and swirl and injected fuel are mixed smoothly.

Therefore, as a fuel injection device that solves this problem, for example, as disclosed in Japanese Utility Model Application Publication No. 59-135377, a buffer chamber is provided in the middle of the fuel supply pipe connecting the fuel injection nozzle and the fuel injection pump. At the same time, when the pressure of the fuel supply pipe exceeds a predetermined value, a valve is provided to listen for communication with the fuel supply pipe of the buffer chamber, and the valve is opened when the fuel pressure rises after fuel injection in the early stage of combustion to release the fuel. A method has been proposed in which the amount of fuel injected at the initial stage of combustion is reduced by lowering the pressure and interrupting fuel injection. According to this, it is possible to suppress premixed combustion while preventing interference of pressure waves in the fuel supply pipe and poor mixing of swirl and injected fuel, such as in the case of (1) stopping.

However, in proposal-C, since the fuel injected at the beginning of combustion is further injected into the burning area, the fuel after being injected into the flame is prevented from mixing with fresh air, and the fuel is injected into the flame. A large amount of smoke (soot) is generated due to the shortage (
In this case, there is a problem in that the engine output decreases.

By the way, as a fuel injection nozzle for a direct injection diesel engine as described above, a nozzle body is provided with a fuel supply passage and a plurality of nozzle holes communicating with the fuel supply passage, and the nozzle holes are connected to the fuel supply passage. Generally, communication is opened and closed by lifting a needle valve.

The present invention has been made in view of the above points, and its purpose is to provide a time difference in the injection timing of fuel from each nozzle hole provided in the nozzle body, thereby reducing the interference of pressure waves and preventing swirl and injection. The object of the present invention is to reduce the amount of fuel stagnation at the initial stage of combustion without causing poor mixing with the fuel and while supplying sufficient air to the injected fuel from each nozzle hole.

(Means for Solving the Problems) In order to achieve the above object, the solving means of the present invention includes a fuel supply passage in a nozzle body and communication with the fuel supply passage. !
The present invention is based on a fuel injection nozzle for a direct injection diesel engine, which is provided with a nozzle hole and whose communication with the fuel supply passage is opened and closed by lifting a needle valve. The nozzle holes are arranged to be offset in the lift direction of the needle valve and in the circumferential direction, and the needle valve has one end communicating with the fuel supply passage and the other end in the lift position of the needle valve. The structure is such that an injection passage communicating with the corresponding injection hole is provided.

(For f'f'') With the above configuration, in the present invention, as the needle valve lifts, the nozzle holes communicate with the fuel supply passage via the injection passage in the order in which the needle valves are arranged. Since the fuel is injected with a time lag, the number of fuel nozzles in the early stages of combustion is reduced, and premix combustion is suppressed.

Furthermore, since the fuel supply passage is a single passage, no pressure wave interference occurs.

Moreover, since only one fuel injection nozzle is required for each cylinder, it is possible to arrange the fuel injection nozzle at the center of the cylinder, and the swirl and the injected fuel can be mixed well.

Roughly speaking, since there is a time difference in fuel injection for each nozzle hole, and fuel 1 is injected from each nozzle hole in a direction specific to each nozzle hole, the air utilization rate is improved, and smoke generation and A decrease in engine output is prevented.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows a subscript I injection nozzle of a direct injection diesel engine according to a first embodiment of the present invention, and 1 is a nozzle body whose tip is arranged facing the combustion chamber of each cylinder of the direct injection diesel engine. A fuel supply passage 2 is formed inside the nozzle body 1, and a fuel pressure chamber 3 is provided at the tip of the fuel supply passage 2, and high pressure is supplied from the fuel injection pump through the fuel supply passage 2. of fuel will be supplied.

At the tip of the nozzle body 1, a sack portion 4 is formed which has a smaller diameter than the fuel pressure chamber 3 and communicates with the fuel pressure chamber 3. At the tip of the nozzle body 1, first to fourth injection holes 5a to 5d, which communicate with the knuck portion 4 and inject fuel into the combustion chamber, are provided so as to be offset in the circumferential direction of the nozzle.

Further, the fuel pressure chamber 3 is provided with a needle valve 6 that opens and closes communication with the fuel pressure chamber 3 (fuel supply passage 2) of the injection holes 5a to 5d. It is fitted so that it can move freely and is biased toward the tip of the nozzle body by a spring. The needle valve 6 is formed with a pressure receiving part 7 that receives the oil pressure of the fuel pressure chamber 3, and a piston part 8 that fits into the sack part 4 in a liquid-tight manner. It is designed to lift toward the rear end of the nozzle body.

As a feature of the present invention, FIGS. 1 and 3(a)
As shown in the figure, the two nozzle holes 5a to 5d are arranged offset in the direction toward the needle valve 6 71. That is, the first and third nozzle holes 5a and 5c are provided on the tip side of the sack portion 4, whereas the second and fourth nozzle holes 5b and 5d are provided on one end side of the sack portion. Further, as shown in FIG. 2, the first and third nozzle holes 5a and 5c and the second and fourth nozzle holes 5b and 5d are formed at symmetrical positions with respect to the center of the nozzle body, and the second and fourth nozzle holes Nozzle holes 5b, 5d
is formed at a position deviated from the center of the nozzle body by more than 90 degrees in the direction of swirl rotation than the first and third nozzle holes 5a and 5c. Furthermore, the first and third nozzle holes 5a and 5c are formed to have a smaller diameter than the second and fourth nozzle holes 51) and 5d.

The needle valve 6 is provided around the piston portion 8 so that one end communicates with the fuel pressure chamber 3 (fuel supply passage 2) and the other end communicates with the nozzle holes 5a to 5d corresponding to the relief position of the needle tP6. The injection passage 9 that opens to the injection passage 9 is spaced by -2, and the piston portion 8 near the injection hole side opening of the 111tA passage 9 has an injection o1 supply passage of the injection hole other than the injection hole that communicates with the injection passage 9. A seal portion 10 is formed to close communication with 2.

Next, to explain the operation of the above embodiment, when the oil pressure in the fuel pressure chamber 3 rises and the needle valve 6 lifts, the first and third nozzle holes 5a and 5c on the front end side of the sack portion first open the injection passage 9. The second and fourth nozzle holes 5b and 5d on the rear end side of the sack part communicate with the fuel supply passage 2 through the seal part 1.
0, and as shown by diagonal lines in Fig. 3(b) and (C), from the first and third injection holes 5a and 5c a small amount of fuel according to the gn rule is mainly premixed combustion. served.

When the needle valve 6 further lifts, the second and fourth nozzle holes 5b and 5d communicate with the fuel supply passage 2 via the injection passage 9, and the first and third nozzle holes 5a and 5c communicate with each other through the seal portion. 10, and a large amount of fuel is injected from the second and fourth nozzle holes 5b and 5d according to the nozzle hole diameter, as shown in white in FIGS. 3(b) and 3(c), and is mainly subjected to diffusive combustion. Ru.

Therefore, in J3 of the first embodiment, fuel is injected from the first and third nozzle holes 5a and 5c and the second and fourth nozzle holes 5b and 5d with a time difference, so that the The fuel injection amount is reduced, premix combustion is suppressed, and the generation of noise and nitrogen oxides can be suppressed.

Further, since the fuel supply passage 2 is a single passage, interference of pressure waves of the fuel does not occur.

Moreover, since only one fuel injection nozzle is required for each cylinder, it is possible to place the fuel tent nozzle in the center of the cylinder, and the swirl and injection) 1 fuel rl can be mixed well, resulting in an excellent Flammability can be reduced to 17.

Furthermore, since a time difference is provided in the fuel injection Oj for each nozzle hole 5a to 5d, and the fuel is injected from each nozzle hole 5a to 5d in a direction unique to each nozzle hole and mixed with air, air utilization is improved. It is possible to improve the efficiency and prevent the occurrence of smoke and a decrease in engine output.

L 7'+1 mo, m 2 and U 411n 7t,
5b, 5d C first and third nozzle holes 5a, 5
It is formed at a position more than 90 degrees away from the center of the nozzle body in the direction of swirl rotation than in Figure 3 (c).
As shown in b), the fuel can be injected from the second and fourth nozzle holes 5b and 5d so as not to be affected by the flame caused by the injected fuel from the first and third nozzle holes 5a and 5c riding on the swirl (arrow). This makes it possible to further improve the combustibility of the injected fuel.

Further, FIGS. 4(a) to 4(C) show a second embodiment of the present invention, in which first to fourth nozzle holes 5'a of small diameter are provided on the tip side of the sack portion 4.
5'd to 5'd, and large-diameter fifth to eighth nozzle holes 5'e to 5'b are provided on the rear end side of the sack portion 4. It is located between the two. According to this fuel injection nozzle, in addition to the effects of the first embodiment, the fuel injection amount at full load can be set to a larger amount due to the larger number of injection holes.

Furthermore, FIGS. 5(a) to 5(C) show a third embodiment of the present invention.
Fourth nozzle holes 5''a to 5''d are provided, and the diameters of the nozzle holes become larger in the order in which they are arranged. According to this fuel gn injection nozzle, in addition to the effects of the first embodiment, fuel injection characteristics similar to those of throttle injection can be obtained as shown in FIG. 5(C).

(Effects of the Invention) As explained above, according to the fuel injection nozzle for a direct injection diesel engine of the present invention, a plurality of nozzle holes are provided in the nozzle body and are shifted in the lift direction of the needle valve and in the circumferential direction, and the needle As the valves move toward the rift L, the nozzle holes communicate with the fuel supply passage in the order in which the needle valves are arranged.
The amount of fuel injected at the beginning of combustion (moon) is reduced to suppress premix combustion and reduce noise while ensuring good mixing of fuel with air and without interference of fuel pressure waves or poor mixing between swirl and injected fuel. and nitrogen oxides.

[Brief explanation of the drawing]

1 to 3 show a first embodiment of the present invention, in which FIG. 1 is a longitudinal sectional view of the tip of a fuel injection nozzle, FIG. 2 is a view of the fuel injection nozzle seen from the tip side, and FIG. Figure (a) is a diagram showing the height of each injection hole, Figure (b) is an explanatory diagram showing the distribution of fuel injected from each injection hole in the combustion chamber, and Figure (C) is a diagram showing the fuel injection characteristics. It is a diagram. 4(a) to 4(C) are views corresponding to FIG. 3 in the second embodiment of the present invention, and FIG. 5 is a view corresponding to FIG.
FIG. 3 is a diagram corresponding to FIG. 3 in the embodiment. 1... Nozzle body, 2... Fuel supply passage, 5a~
5d... Nozzle hole, 6... Needle valve, 9... Injection passage, 10... Seal portion. <-11 Figure 3 (G) Figure 3 (b) Figure 4 (C
I) Figure 4 (b) Figure 5 (Q)
Figure 5 (b) Gezoku suburban circular surface direction - RF + q - Figure 3 (C) Figure 4 (C) Figure 5 (C time

Claims (1)

[Claims] (1) A direct-injection diesel engine in which a nozzle body is provided with a fuel supply passage and a plurality of nozzle holes communicating with the fuel supply passage, and the communication between the nozzle holes and the fuel supply passage is opened and closed by lifting a needle valve. In the fuel injection nozzle of the engine, the injection holes are arranged to be offset in the lift direction and circumferential direction of the needle valve, and the needle valve has one end communicating with the fuel supply passage and the other end communicating with the needle valve. A fuel injection nozzle for a direct injection diesel engine, characterized in that an injection passage is provided that communicates with an injection hole depending on the lift position of a valve.