JPH0636289Y2 - Fuel injection device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a fuel supply system for an internal combustion engine.

[Prior Art] A nozzle opening that is electromagnetically controlled by a needle to inject fuel using compressed air is provided, and a compressed air passage extending from the nozzle opening along the needle is formed around the needle. The compressed air passage is connected to a compressed air source, a needle guide that is slidably guided by the inner wall surface of the compressed air passage is integrally formed on the needle near the nozzle opening, and a nozzle chamber that opens in the compressed air passage is provided. Of the fuel injection valve is arranged in the inner part of the fuel injection valve, the fuel is injected from the injection port toward the needle, and then the needle is opened to inject the injected fuel together with the compressed air from the nozzle opening. Air blast valves are known (see Japanese Patent Publication No. 63-500323). In this air blast valve, low-pressure compressed air can be used to ensure good atomization of the injected fuel.

[Problems to be Solved by the Invention] However, when the injection port of the fuel injection valve is arranged in the inner part of the nozzle chamber that opens in the compressed air passage like the above-mentioned air blast valve, when the needle opens, the compressed air nozzle chamber There is a problem that the injected fuel accumulates because the fuel adhering to the inner wall surface of the nozzle chamber cannot be carried away by the compressed air.

[Means for Solving the Problems]

According to the present invention, in order to solve the above problems, a nozzle opening is formed at one end of a needle insertion hole, and a needle having a diameter smaller than that of the needle insertion hole is inserted to electromagnetically control the needle. The valve opening formed at the tip of the needle controls the opening and closing of the nozzle opening to connect the compressed air passage connected to the compressed air source to the needle insertion hole, and to connect the compressed air passage and the needle insertion hole directly on the side opposite to the nozzle opening. An enlarged portion that closes the cross section of the needle insertion hole is formed on the needle adjacent to the portion, and the fuel injection valve is arranged in the compressed air passage.

[Action]

Since the fuel injection valve is arranged in the compressed air passage, the fuel adhering to the inner wall surface of the compressed air passage can be sent into the needle insertion hole by compressed air, and the expanded fuel needle portion causes the fuel to go deeper in the needle insertion hole. Since it can be prevented from entering and adhering to the portion, all the injected fuel is ejected from the nozzle port.

〔Example〕

Referring to FIG. 6 and FIG. 7, 1 is a cylinder block, 2 is a piston, 3 is a cylinder head, 4 is a combustion chamber,
5 is a pair of air supply valves, 6 is an air supply port, 7 is a pair of exhaust valves, 8 is an exhaust port, and 9 is an ignition plug. A mask wall 10 is formed on the inner wall surface of the cylinder head 3 to close the opening between the periphery of the air supply valve 5 on the exhaust valve 7 side and the valve seat over the entire opening period of the air supply valve 5. Therefore, when the air supply valve 5 is opened, fresh air flows into the combustion chamber 4 from the side opposite to the exhaust valve 7 as indicated by arrow A. An air blast valve 20 is arranged on the inner wall surface of the cylinder head 3 located between the pair of air supply valves 5.

FIG. 1 shows a partial cross-sectional side view of the air blast valve 20. Referring to FIG. 1, a needle insertion hole 22 that extends straight is formed in a housing 21 of the air blast valve 20, and a needle 23 having a smaller diameter than the needle insertion hole 22 is inserted into the needle insertion hole 22. A nozzle port 24 is formed at one end of the needle insertion hole 22, and the nozzle port 24 is opened and closed by a valve unit 25 formed at the tip of the needle 23. In the embodiment shown in FIG. 1, this nozzle port 24 is arranged in the combustion chamber 4. In addition, the needle 23 has a spring retainer 26
Fixed, this spring retainer 26 and housing 21
A compression spring 27 is inserted between them. The nozzle opening 24 is normally closed by the valve portion 25 of the needle 23 by the spring force of the compression spring 27. A movable core 28 is constantly brought into contact with the end of the needle 23 on the side opposite to the valve portion 25 by a spring force of a compression spring 29, and a solenoid 30 for attracting the movable core 28 and a stator in the housing 21. 31 are placed. When the solenoid 30 is energized, the movable core 28 moves toward the stator 31, and as a result, the needle 23 moves in the direction of the nozzle opening 24 against the spring force of the compression spring 27, so that the nozzle opening 24 is opened. To be

On the other hand, a cylindrical nozzle chamber 32 is formed in the housing 21. The one end 32a of the nozzle chamber 32 has a compressed air inflow passage 33.
And the other end 32b of the nozzle chamber 32 is connected to the compressed air source 34 via the compressed air outflow passage 35.
It is possible to communicate within 2. The fuel injection valve 3 is installed in the nozzle chamber 32.
Six nozzles 37 are arranged, and the nozzles 37 are located in the nozzle chamber 32 between one end 32a and the other end 32b. As shown in FIG. 1, the compressed air outflow passage 35 extends straight.
The nozzle 37 is arranged on the axis of the compressed air outflow passage 35,
From 37, fuel having a small spread angle is injected along the axis of the compressed air outflow passage 35. The compressed air outflow passage 35 extends obliquely toward the nozzle opening 24 with respect to the needle insertion hole 22, and is obliquely connected to the needle insertion hole 22 at an angle of 20 to 45 degrees with respect to the needle insertion hole 22. Needle insertion hole 22
It is possible to communicate in the inside. As shown in FIGS. 1 and 2, the compressed air outflow passage 35 is provided on the side opposite to the nozzle port 24.
On the needle 23 adjacent to the communicating portion of the needle insertion hole 22, a pair of enlarged portions 40 for closing the cross section of the needle insertion hole 22 are formed. In the embodiment shown in FIGS. 1 and 2, the enlarged portion 40 has a substantially cylindrical shape, and both end portions 40a, 40b thereof are formed in a conical shape. In FIG. 2, the solid line shows the needle 23 in the valve closed state, and the broken line shows the needle 23 in the valve opened state. Therefore, as can be seen from FIG. 2, when the needle 23 is closed, the enlarged portion 40
The lower end of the compressed air outflow passage for the needle insertion hole 22
When the needle 23 is opened, the lower end of the expanded portion 40 is located at the upper line of the communication opening 35 and covers a part of the communication opening. The enlarged portion 40 serves to hold and guide the needle 23 at a predetermined position in the needle insertion hole 22, and as will be described later, the inner portion of the needle insertion hole 22, that is, the needle insertion hole above the enlarged portion 40 in FIG. It plays the role of preventing the fuel from entering and adhering to the inside of 22.

Needle insertion hole 22, nozzle chamber 32 and compressed air outflow passage
35 communicates with a compressed air source 34 via a compressed air inflow passage 33. Therefore, the needle insertion hole 22, the nozzle chamber 32 and the compressed air outflow passage 35 are filled with compressed air. Fuel is injected into the compressed air from the injection port 37 into the compressed air outflow passage 35 along the axis. As shown in FIG. 1, the compressed air outflow passage 35 is obliquely connected to the needle insertion hole 22, and the injected fuel is prevented from entering the inner portion of the needle insertion hole 22 by the enlarged needle portion 40. Most of the injected fuel reaches the needle insertion hole 22 around the needle 23 near the valve portion 25. At this time, a part of the fuel adheres to the inner wall surface of the compressed air outflow passage 35 and the inner wall surface of the nozzle chamber 32. Then when the solenoid 30 is energized, the needle 23
Opens the nozzle port 24. At this time, since the injected fuel is gathered near the valve portion 25, as soon as the needle 23 opens the nozzle opening 24, both the fuel and the compressed air are discharged from the nozzle opening 24 into the fuel chamber 4.
Gush out inside. Further, at this time, since the expanded needle portion 40 is also moved toward the nozzle opening 24, the fuel attached to the inner wall surface of the needle insertion hole 22 near the expanded needle portion 40 is scraped off by the conical end 40a of the expanded needle portion 40. .
Further, when the needle 23 opens the nozzle port 24, the compressed air flows into the nozzle chamber 32 from the compressed air inflow passage 33, and then passes through the compressed air outflow passage 35 toward the nozzle port 24, so that the compressed air outflow passage 35 The fuel adhering to the inner wall surface and the inner wall surface of the nozzle chamber 32 is carried away by the compressed air flow and ejected from the nozzle port 24. Therefore, as soon as the needle 23 opens, all of the injected fuel is ejected from the nozzle port 24, and when the ejection of all the injected fuel is completed, only compressed air is ejected from the nozzle port 24. Next, the solenoid 30 is deenergized and the needle 23 closes the nozzle port 24. Therefore, just before the needle 23 is closed, only the air is ejected from the nozzle port 24. If the fuel is still ejected from the nozzle opening 24 immediately before the needle 23 is closed, the fuel is not atomized when the opening area of the nozzle opening 24 is reduced and the flow velocity of the compressed air is reduced when the needle 23 is closed. The liquid fuel adheres around the nozzle opening 24. When the liquid fuel adheres to the periphery of the nozzle opening 24 as described above, carbon is deposited around the nozzle opening 24, which hinders the fuel injection action. However, in the embodiment shown in FIG. 1, only the compressed air is ejected immediately before the needle 23 is closed, so that liquid fuel does not adhere to the vicinity of the nozzle opening 24, and therefore carbon is deposited around the nozzle opening 24. There is no danger.

3 and 4 show another embodiment of the expanded needle portion. In this embodiment, the enlarged needle portion 41 is the needle insertion hole.
It is arranged so as to cover the communication opening of the compressed air outflow passage 35 with respect to 22, and a notch 41a is formed on the outer peripheral surface of the expanded needle portion 41 facing this communication opening. In this embodiment, since the injected fuel collides with the surface of the notch 41a having a small surface area, the amount of the adhered fuel around the communication opening is reduced, and the fuel fed into the needle insertion hole 22 near the needle valve portion 25 is accordingly reduced. There is an advantage that the amount can be increased.

FIG. 5 shows a case where the compressed air outflow passage 35 'is connected to the needle insertion hole 22 at a right angle.

FIG. 7 shows a case where the air blast valve 20 is applied to a two-cycle engine, and fuel injection from the air blast valve 20 is started just before the air supply valve 5 is closed. During engine low load operation, the flow velocity of the fresh air A flowing into the combustion chamber 4 is slow, so the injected fuel gathers around the spark plug 9, and thus good ignition is performed. On the other hand, during high engine load operation, the flow velocity of the fresh air A is high, so strong loop scavenging is performed,
Moreover, since the injected fuel is carried along the inner wall surface of the combustion chamber 4 by the new air flow A flowing in a loop, a uniform air-fuel mixture is formed in the combustion chamber 4. As a result, high engine output can be secured.

[Effect of device]

The fuel injection valve is arranged in the compressed air passage, and an enlarged portion is formed in the needle, and the enlarged portion prevents the injected fuel from entering the inner portion of the needle insertion hole. All fuel can be ejected with compressed air. As a result, the injected fuel amount does not vary, and thus stable combustion can be ensured.

[Brief description of drawings]

1 is a partial sectional side view of an air blast valve, FIG. 2 is an enlarged sectional view of a portion indicated by an arrow K in FIG. 1, FIG. 3 is an enlarged sectional view showing another embodiment, and FIG. 3 is a side view taken along the arrow IV in FIG. 3, FIG. 5 is an enlarged sectional view showing still another embodiment, FIG. 6 is a bottom view of the inner wall surface of the cylinder head, and FIG. 7 is a side sectional view of a two-cycle engine. It is a figure. 20 ... Air blast valve, 22 ... Needle insertion hole, 23 ... Needle, 24 ... Nozzle port, 30 ... Solenoid, 32 ... Nozzle chamber, 33 ... Compressed air inflow passage, 34 ... Compressed air source, 35 ... Compressed air outflow passage, 36 ... Fuel injection valve, 37 ... Nozzle port, 40, 41 ... Enlarged part.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takataka Cho Nao, 1-1, Showa-cho, Kariya city, Aichi Nihon Denso Co., Ltd. (56) References Special table Sho 63-500323 (JP, A)

Claims (1)

[Scope of utility model registration request] A nozzle opening is formed at one end of a needle insertion hole, a needle having a diameter smaller than that of the needle insertion hole is inserted into the needle insertion hole, and the needle is electromagnetically controlled to be formed at the needle tip. The valve opening and closing is controlled by the valve portion to connect the compressed air passage connected to the compressed air source to the needle insertion hole and the needle adjacent to the communication portion between the compressed air passage and the needle insertion hole on the side opposite to the nozzle opening. A fuel injection device for an internal combustion engine, in which an enlarged portion that closes a cross section of a needle insertion hole is formed above and a fuel injection valve is arranged in the compressed air passage.