JPS621388Y2 - - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to a fuel-injected internal combustion engine.

In so-called simultaneous injection internal combustion engines, in which the fuel injection valves installed in the intake passages of each cylinder are activated simultaneously, the fuel injection timing and the intake stroke do not match, so the fuel injected from the fuel injection valves is injected into the intake passage. When the intake valve opens, the accumulated fuel flows into the combustion chamber all at once. On the other hand, after the accumulated fuel flows into the combustion chamber, there is no more fuel in the intake passage, so only air is supplied into the combustion chamber. When an internal combustion engine has a structure that forms an intake swirl, the fuel that has flowed into the combustion chamber is retained while swirling on the top surface of the piston from the intake stroke to the compression stroke, so that the fuel is concentrated on the top surface of the piston. The mixture gathers, and a lean mixture gathers above the combustion chamber. Normally, in an internal combustion engine, an ignition plug is installed at the top of the combustion chamber in order to shorten the propagation distance of the ignition flame as much as possible and increase the combustion speed, but as mentioned above, the lean mixture gathers above the combustion chamber, making it difficult to ignite. The problem is that it is bad. Such problems become particularly noticeable when a lean mixture is supplied to the combustion chamber.

The object of the present invention is to provide an internal combustion engine in which two spark plugs are provided in a combustion chamber and these spark plugs are operated selectively to increase the combustion speed while ensuring good ignition performance. .

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIGS. 1 and 2, 1 is a cylinder block, 2 is a piston, 3 is a cylinder head fixed onto the cylinder block 1 via a spacer 4, and 5 is formed between the cylinder head 3 and the piston 2. 6 is an intake valve, 7 is a helical intake port, 8 is an exhaust valve, and 9 is an exhaust port. A fuel injection valve 10 is disposed within the intake port 7 , and fuel is injected from the fuel injection valve 10 toward the back surface of the intake valve 6 . On the other hand, combustion chamber 5
A first ignition plug 11 is arranged at the top of the spacer 4, and a second ignition plug 12 is arranged inside the spacer 4. Fuel injection valve 10, first spark plug 11, and second spark plug 1
2 is connected to an electronic control unit 13 that controls fuel injection amount and ignition timing.

A fuel injection valve 10 is provided for each cylinder and is operated simultaneously by an output signal from an electronic control unit 13. The fuel injection amount is determined according to the operating state of the engine based on output signals from an air flow meter for measuring intake air (not shown) and an engine speed sensor. For example, when the amount of intake air is small, the fuel injection amount is controlled so that a lean mixture is supplied into the combustion chamber 5, and when the amount of intake air is large, a rich mixture is supplied into the combustion chamber 5, or a mixture at a stoichiometric air-fuel ratio. The fuel injection amount is controlled so that air is supplied. fuel injection valve 1
Generally, the injection timing of 0 and the opening timing of the intake valve 6 do not coincide with each other. Therefore, part of the fuel injected from the fuel injection valve 10 collides with the back surface of the intake valve 6 and evaporates, and the remaining fuel is attached on the inner wall surface of the intake port 7. Next, when the intake valve 6 opens, the intake air flows into the combustion chamber 5 together with the fuel, generating a swirling flow within the combustion chamber 5. Since the fuel in the intake port 7 flows into the combustion chamber 5 at the beginning of the intake stroke, only air flows into the combustion chamber 5 at the latter half of the intake stroke. Therefore, the swirling rich mixture gathers on the top surface of the piston 2, while the mixture above the combustion chamber 5 becomes thinner than the rich mixture on the top surface of the piston 2. If the air-fuel mixture formed by the fuel injected from the fuel injection valve 10 is a lean air-fuel mixture, the air-fuel mixture above the combustion chamber 5 will be quite lean, but the air-fuel mixture will be relatively rich above the top surface of the piston 2. be done. In this case, the second spark plug 12 is actuated by the output signal of the electronic control unit 13, and the relatively rich air-fuel mixture on the top surface of the piston 2 is ignited. Therefore, ignitability is improved. On the other hand, when the air-fuel mixture formed by the fuel injected from the fuel injection valve 10 is a rich air-fuel mixture or has a stoichiometric air-fuel ratio, the air-fuel mixture above the combustion chamber 5 does not become very lean, and therefore, at this time, the first spark plug 11 is activated and the mixture flows to the first spark plug 11.
ignited by. In the case of ignition by the first spark plug 11, the flame propagation distance is short, thus increasing the combustion speed. A rich air-fuel mixture is supplied into the combustion chamber 5 when the amount of intake air is large or when high engine output is required, such as during high-load operation. 11 to ignite the air-fuel mixture to increase the combustion speed and ensure high engine output.

As described above, according to the present invention, good ignitability can be ensured even if the air-fuel mixture supplied into the engine cylinder is a lean mixture, while the air-fuel mixture supplied into the engine cylinder is rich. At the time of a high amount of intake air forming a mixture, or during high load operation, the combustion speed can be increased to ensure high engine output. Further, even when the mixture supplied into the combustion chamber 5 becomes a lean mixture due to the supply of EGR gas, it is necessary to ignite the mixture using the second ignition plug.

[Brief explanation of the drawing]

FIG. 1 is a bottom view of the cylinder head, and FIG. 2 is a side view of the internal combustion engine. 6... Intake valve, 7... Helical intake port,
8... Exhaust valve, 10... Fuel injection valve, 11... First spark plug, 12... Second spark plug.

Claims (1)

[Scope of utility model registration request] In an internal combustion engine equipped with a fuel injection valve in the intake passage, a first spark plug is placed at the top of the combustion chamber, and a second spark plug is placed at the bottom of the combustion chamber to control the air-fuel mixture supplied into the combustion chamber. When the mixture is a lean mixture, the mixture is ignited by the second ignition plug, and when the mixture supplied into the combustion chamber has a stoichiometric air-fuel ratio or a rich mixture, the mixture is ignited by the first ignition plug. A fuel-injected internal combustion engine.