JPS6327093Y2 - - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to a fuel injection device for an internal combustion engine.

For example, in internal combustion engines such as diesel engines that inject fuel into the combustion chamber, the swirl strength and the number of nozzles in the fuel injection nozzle greatly affect the mixing of the fuel spray and intake air. When the number of nozzles is small, it is preferable to strengthen the swirl in order to obtain good mixing and improve combustibility.

However, the strength of the swirl is not constant over the entire engine speed range, but tends to become stronger as the engine speed increases, so if you adjust the swirl amount to one of the low, medium, and high engine speed ranges, , matching is not possible in other engine speed ranges. For example, if matching is done in the middle engine speed range, the swirl will be too strong in the high speed range and the sprayed fuel will overlap, while in the low speed range the swirl will be weak and the sprayed fuel will not be sufficiently diffused, resulting in optimal combustion. was not obtained.

For this reason, variable swirl mechanisms have been proposed that change the amount of swirl according to the engine speed to obtain the optimum swirl over the entire rotation range (Jikkosho).
No. 51-7365, etc.), but in this case, the throttle device in the intake passage not only reduces the air filling efficiency and causes output loss, but also makes the device complicated and difficult to put into practical use. In addition, an injection nozzle has been proposed that has a plurality of needle valves with different set pressures and a plurality of nozzle groups that inject fuel only by the lift of the corresponding needle valves. (Sho 51-582165, etc.)

In this invention, a fuel injection nozzle having two fuel passages in which different fuel injection openings communicate through a needle valve is installed in the engine combustion chamber, and when the engine is running at low speeds, the fuel injection nozzle with many fuel injection openings is placed on the side of the fuel passage where there are many fuel injection openings. The purpose of this invention is to solve the conventional problems by switching and supplying fuel to the fuel passage side where there are fewer fuel injection ports during rotation, thereby making the number of injection ports substantially variable.

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

In FIG. 1, 1 is a cylinder head, 2 is a cylinder block, 3 is a piston, and 4 is a combustion chamber. 5 is a fuel injection nozzle installed in the combustion chamber 4;
Fuel supplied from the fuel injection pump 6 is supplied to the combustion chamber 4.
Inject inside. The configuration of the injection nozzle 5 will be explained in detail later. Reference numeral 7 denotes a rotation speed sensor as an engine rotation speed detection means for detecting and outputting the engine rotation speed, and the output from this sensor 7 switches a switching valve 8 as a fuel supply switching means, which is installed in the injection nozzle 5. One of the two fuel passages is connected to a fuel injection pump 6.

The structure of the fuel injection nozzle 5 is shown in FIGS. 2 and 3.
This will be explained based on the diagram.

In the figure, a nozzle holder 11 and a nozzle body 12 of a fuel injection nozzle 5 are tightened and fixed together by a nozzle nut 13. Nozzle body 1
A plurality of fuel injection ports 14 are formed at the tip of the nozzle body 12. As shown in FIG. 4 on the outside, 5 on the outside
The two injection ports 14 are located at approximately equal intervals. A first needle valve 15 that opens and closes the five outer injection ports 14A is fitted into the nozzle holder 11 and nozzle body 12, and a second needle valve 15 that opens and closes the inner injection ports 14B is inserted into the first needle valve 15. A needle valve 16 is inserted.

On the other hand, a first adjuster screw 17 having upper and lower recesses 17A and 17B is screwed into the upper end of the nozzle holder 11. The inner wall of the lower recess 17B of the adjusting screw 17 and the first needle valve 15
A first spring 18 is interposed between the first needle valve 15 and the top wall of the first needle valve 15 to always bias the first needle valve 15 in the valve closing direction. Further, a second adjusting screw 19 is screwed into the upper recessed portion 17A of the first adjusting screw 17 and fixed with a nut 20. A spring seat 21 is fitted to the upper outer periphery of the second needle valve 16 that passes through the first and second adjusting screws 17 and 19, and the spring seat 21 and the inner wall of the top of the second adjusting screw 19 are fitted. A second spring 23 is interposed between the second needle valve 16 and a spring seat 22 fixed to the second needle valve 16 to always bias the second needle valve 16 in the valve closing direction. Incidentally, on the outer periphery of the second needle valve 16, there is a ring-shaped member 2 that forms a locking portion for locking the spring seat 21.
4 is integrally attached to the second needle valve 16.

Further, the nozzle holder 11 has a first and a second two.
Two fuel inlet ports 25 and 26 are formed, and the first fuel inlet port 25 connects the first needle valve 15 and the nozzle body 1 shown in FIG.
This fuel reservoir 28 communicates with the outer fuel injection port 14A via the fuel passage 31 and the first needle valve 15. On the other hand, the second fuel inlet 26 is connected to the first needle valve 15 and the second needle valve 1 through a fuel passage 29 as shown in FIG. 3A.
The fuel reservoir 30 communicates with the inner fuel injection port 14B via the fuel passage 32 and the second needle valve 16.

Next, the effect will be explained.

When the engine rotation speed is low, the rotation speed sensor 7
detects this and outputs it, and this output drives the switching valve 8 to communicate the fuel injection pump 6 and the first fuel inlet 25 of the fuel injection nozzle 5. Thereby, fuel from the injection pump 6 is supplied into the fuel injection nozzle 5 via the first fuel inlet 25 and guided to the fuel reservoir 28 via the fuel passage 27. The fuel pressure in this fuel reservoir 28 is the first spring 1
When the load exceeds the set load of 8, the first needle valve 15
It moves upward against the spring 18 and injects fuel into the combustion chamber 4 from the five outer fuel injection ports 14A.

On the other hand, when the engine rotational speed becomes medium or high, the switching valve 8 is switched according to the output from the rotational speed sensor 7, and the fuel injection pump 6 and the second fuel inlet 26 are communicated with each other. Therefore, the fuel from the injection pump 6 passes through the second fuel inlet 26 to the fuel injection nozzle 5.
supplied to Fuel supplied from the second fuel inlet 26 is introduced into a fuel reservoir 30 between the first needle valve 15 and the second needle valve 16 via the fuel passage 29.
When the fuel pressure in this fuel reservoir 30 reaches the set load of the second spring 23 or more, the second needle valve 16
moves upward against the second spring 23, and fuel is injected into the combustion chamber 4 from the four inner fuel injection ports 14B.

In this way, at low engine speeds with weak swirl, fuel is injected from many injection ports to compensate for the lack of swirl and make it easier to spread the atomized fuel, resulting in better mixing of fuel and air, resulting in better combustion. It will be done. On the other hand, when the swirl is too strong, such as when the engine is running at high speed, the number of injection ports for injecting fuel is reduced to reduce the overlap of the atomized fuel and efficiently diffuse the fuel, resulting in good combustion. Furthermore, since there is no need to reduce the cross-sectional area of the passage in the intake system, it goes without saying that a sufficient amount of air can be secured without impairing air filling efficiency.

Note that the number of fuel injection ports is not limited to that of this embodiment.

As described above, according to the present invention, the actual number of injection ports of the fuel injection nozzle is made variable according to the engine rotation speed, and fuel is injected from more injection ports at low speeds than at medium and high speeds. Even when the swirl is weak at low speeds, the atomized fuel can be sufficiently diffused and good combustion can be achieved. Therefore, there is no need to provide a throttling device to enhance swirl, and optimum combustion can be obtained in the entire rotational speed range of the engine without impairing air filling efficiency.

[Brief explanation of drawings]

FIG. 1 is a simplified configuration diagram showing one embodiment of the present invention;
Figure 2 is a partial cross-sectional configuration diagram of the fuel injection nozzle;
Figure A is an enlarged sectional view showing the tip of the nozzle in Figure 2;
FIG. 3B is a view taken along arrow A in FIG. 5...Fuel injection nozzle, 6...Fuel injection pump, 7...Rotational speed sensor, 8...Switching valve, 14
...Fuel injection port, 15...First needle valve, 16...Second needle valve, 25...First fuel inlet, 26...Second
Fuel inlet, 27, 29... fuel passage.

Claims (1)

[Scope of utility model registration request] a fuel injection nozzle provided in an engine combustion chamber and having two fuel passages through which different numbers of fuel injection ports communicate via needle valves; an engine rotation speed detection means for detecting and outputting an engine rotation speed; a fuel supply switching means for switching a fuel passage through which fuel is supplied from the injection pump according to the output of the detection means;
The switching means switches to the fuel passage side with many fuel injection ports when the detection means detects a low engine speed, and switches to the fuel passage side with fewer fuel injection ports when the detection means detects a middle/high engine speed. A fuel injection device for an internal combustion engine, characterized in that the fuel injection device is configured to switch to the passage side.