JP2518278Y2 - Fuel injection device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a fuel injection device for an internal combustion engine.

[Conventional technology]

JP-A-60-501963 discloses that a nozzle port is formed at one end of an injection chamber and a compressed air passage is connected to the other end, and a fuel supply passage is connected between one end and the other end of the injection chamber. , A solenoid valve that is opened by energizing a solenoid that is normally spring-biased in the valve closing direction is provided in the nozzle port, and at the same time when this solenoid valve is opened, the fuel supplied from the fuel supply passage into the injection chamber is A fuel injection device is disclosed in which compressed air supplied from a compressed air passage into the injection chamber is injected from a nozzle port.

In this fuel injection device, when the solenoid valve opens, the compressed air flows through the injection chamber, and the fuel adhering to the inner wall surface of the injection chamber can be carried away by the compressed air.

[Problems to be solved by the device]

However, in this fuel injection device, compressed air hardly flows in the fuel supply passage when the solenoid valve is opened,
Thus, the fuel adhering to the inner wall surface of the fuel supply passage cannot be carried away by the compressed air. Therefore, there is a problem in that the measured amount of fuel is not entirely injected and the accuracy of the injected fuel amount is reduced.

Particularly, when the fuel injection amount is small, the variation of the injected fuel becomes large.

[Means for solving the problem]

In order to solve the above-mentioned problems, a fuel injection device for an internal combustion engine according to the present invention is a first compressed air passage having a nozzle opening formed at its tip, and a driving means arranged at its end inside thereof. A first compressed air passage extending from the nozzle opening / closing means connected to the first compressed air passage, and the first compressed air passage is obliquely communicated with the first compressed air passage toward the nozzle opening, and the other end is provided with a fuel injection valve. Fuel supplied from the fuel supply passage and the fuel injection valve into the first compressed air passage through the fuel supply passage is injected from the nozzle opening by the compressed air supplied to the first compressed air passage. A second compressed air passage that connects a compressed air source near the other end of the fuel supply passage, and a bypass passage that communicates between the other end of the fuel supply passage and the end of the first compressed air passage. Must be equipped with The features.

[Action]

In the above-described fuel injection device for an internal combustion engine, the compressed air supplied from the compressed air source is supplied to the other end of the fuel supply passage where the fuel injection valve is arranged, after passing through the second compressed air passage, and then the fuel supply passage. The fuel that is injected from the fuel injection valve and adheres to the fuel supply passage because it is injected through the nozzle opening of the first compressed air passage through the nozzle is ejected from the nozzle opening together with the compressed air without remaining there, and A part of the compressed air flows from the other end of the fuel supply passage through the bypass passage to the first
Since the compressed air passage goes from the end to the nozzle port, the fuel does not flow backward from the fuel supply passage communicating portion to the drive means side in the first compressed air passage.

〔Example〕

2 and 3, 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, and 7 is a pair of exhaust valves. 8 is an exhaust port, and 9 is a spark 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, the housing 21 of the air blast valve 20.
A needle insertion hole 22 that extends straight inside is formed,
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.
Opening and closing is controlled by the valve portion 25 formed at the tip of the.
In the embodiment shown in FIG. 1, this nozzle port 24 is arranged in the combustion chamber 4. The needle 23 has a spring retainer.
26 is fixed, and this spring retainer 26 and housing
A compression spring 27 is inserted between 21. 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 nozzle chamber 32 has a compressed air source 34 on a peripheral portion 32a thereof via a compressed air inflow passage 33 which is a second compressed air passage.
The nozzle chamber 32 is communicated with the needle insertion hole 22 via the bypass air passage 40 on the peripheral portion 32b opposite to the peripheral portion 32a. Furthermore, the nozzle chamber 32
The needle insertion hole 2 through the fuel supply passage 35 at the top 32c.
It is possible to communicate within 2. The distance from the nozzle opening 24 to the opening position of the fuel supply passage 35 into the needle insertion hole 22 is
From the nozzle port 24 to the needle insertion hole of the bypass air passage 40
It is about 1/2 of the distance to the opening position inside 22. The needle insertion hole 22 constitutes a first compressed air passage. An injection port 37 of a fuel injection valve 36 is arranged in the nozzle chamber 32, and further, this injection port 37
Is located between the peripheral portions 32a, 32b and the top portion 32c in the nozzle chamber 32. As shown in FIG. 1, the fuel supply passage 35 extends straight. The nozzle 37 is arranged on the axis of the fuel supply passage 35, and the fuel having a small spread angle is injected from the nozzle 37 along the axis of the fuel supply passage 35. The fuel supply 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. The bypass air passage 40 extends straight and extends obliquely with respect to the needle insertion hole 22 toward the nozzle opening 24, and forms 30 degrees to 70 degrees with respect to the needle insertion hole 22.
22 diagonally connected.

The needle insertion hole 22, the nozzle chamber 32, the fuel supply passage 35, and the bypass air passage 40 communicate with the compressed air source 34 via the compressed air inflow passage 33. Therefore, the needle insertion hole 22, the nozzle chamber 32, the fuel supply passage 35, and the bypass air passage 40 are filled with compressed air. Fuel is injected from the injection port 37 into the compressed air along the axis of the fuel supply passage 35. As shown in FIG. 1, since the fuel supply passage 35 is obliquely connected to the needle insertion hole 22, most of the injected fuel is located around the needle 23 near the valve portion 25.
Reach in. At this time, a part of the fuel adheres to the inner wall surface of the fuel supply passage 35. Next, when the solenoid 30 is energized, the needle 23 opens the nozzle port 24. When the nozzle port 24 is opened, compressed air flows from the compressed air inflow passage 33 to the nozzle chamber 32.
Into the nozzle and then through the bypass air passage 40
Go to 24. At this time, since the injected fuel is collected in the vicinity of the valve portion 25, as soon as the needle 23 opens the nozzle port 24, both the fuel and the compressed air are ejected from the nozzle port 24 into the combustion chamber 4. Further, the compressed air flowing into the nozzle chamber 32 goes through the fuel supply passage 35 to the nozzle port 24, so that the compressed air flows into the fuel supply passage.
The fuel adhering to the inner wall surface of 35 is carried away by the compressed air flow and ejected from the nozzle port 24. Therefore, as soon as the needle 23 is opened, all of the injected fuel is ejected from the nozzle port 24, and when the ejection of all these injected fuels is completed, only the compressed air is ejected from the nozzle port 24. In the present embodiment, fuel is supplied from the fuel supply passage 35 into the needle insertion hole 22, and compressed air is supplied to the nozzle port 24 from a position upstream of the fuel supply position into the needle insertion hole 22 via the bypass air passage 40. Since it is made to flow in toward the solenoid, the fuel can be prevented from entering the solenoid 30 and the stator 31 on the upstream side of the needle insertion hole 22. The solenoid 30 is then de-energized and the needle 23
Opens 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. In this way, liquid fuel
If it adheres to the surrounding area, carbon will accumulate around the nozzle opening 24,
This hinders the fuel injection action. However the first
In the embodiment shown in the figure, since only the compressed air is ejected immediately before the needle 23 is closed, the liquid fuel does not adhere to the periphery of the nozzle opening 24, and therefore the risk of carbon deposition around the nozzle opening 24 is reduced. Absent.

FIG. 3 shows a case where the air blast valve 30 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 low engine load operation, the injected fuel collects around the spark plug 9 because the flow rate of the fresh air A flowing into the combustion chamber 4 is low, and thus good ignition is performed. On the other hand, at the time of engine high load operation, a strong loop scavenging is performed because the flow velocity of the fresh air A is high, and the injected fuel is carried along the inner wall surface of the combustion chamber 4 by the fresh air flow A flowing in a loop shape. Inside, a homogeneous mixture is formed. As a result, high engine output can be secured.

The diameter of the bypass air passage 40 is made smaller than the diameter of the fuel supply passage 35, and for example, the diameter of the bypass air passage is 1 mm.
The diameter of the fuel supply passage 35 may be 3.5 mm.

[Effect of device]

Since all the fuel injected from the fuel injection valve is ejected together with the compressed air, the injected fuel amount does not vary,
Thus, stable combustion can be ensured.

[Brief description of drawings]

1 is a partial cross-sectional side view of an air blast valve, FIG. 2 is a bottom view of an inner wall surface of a cylinder head, and FIG. 3 is a side cross-sectional view of a two-cycle engine. 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 ... fuel supply passage, 36 ... fuel injection valve, 37 ... injection port, 40 ... bypass air passage.

Claims (1)

(57) [Scope of utility model registration request] 1. A first compressed air passage (22) having a nozzle opening (24) formed at a tip thereof, in which a nozzle opening opening / closing means connected to a driving means arranged at the end thereof is provided. The extending first compressed air passage (22) and the first compressed air passage (22) communicate with each other obliquely in the direction of the nozzle port (24), and the fuel injection valve (36) is arranged at the other end. The fuel supply passage (35), and the first compressed air passage (2) from the fuel injection valve (36) via the fuel supply passage (35).
2) the fuel supplied into the first compressed air passage (2
The compressed air supplied to 2) causes the nozzle mouth (2
4) A second compressed air passage (33) connecting a compressed air source (34) near the other end of the fuel supply passage (35) for injecting the fuel, and the other end of the fuel supply passage (35) A fuel injection device for an internal combustion engine, comprising: a bypass passage (40) communicating with a vicinity of an end of the first compressed air passage (22).