JPS603332Y2 - Exhaust recirculation device in engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates primarily to exhaust gas recirculation systems for automobiles and other engines that use lean mixtures.

Recently, in this type of engine, in order to prevent the generation of NOx during combustion as much as possible, a lean mixture has been used that is close to the flammability limit or ignition limit. In order to further suppress the occurrence of air pollution, part of the exhaust gas is recirculated to the intake side, but conventionally, this type of device returns the exhaust gas to the upstream side of the intake passage to ensure that it mixes well with the air-fuel mixture in the passage. In general, the air-fuel mixture has a disadvantage in that its ignitability is further reduced and misfires are likely to occur during engine operation.

The purpose of the present invention is to obtain a device that reduces such inconveniences as much as possible. An intake passage having an auxiliary intake passage communicating with a auxiliary carburetor that forms air is connected to a combustion chamber having a spark plug via a valve boat whose opening and closing is controlled by an intake valve, and an exhaust passage within the main intake passage. In an exhaust gas recirculation device for an engine, the exhaust gas recirculation passage is provided with an exhaust gas recirculation passage branching from and communicating with the main intake passage, wherein the auxiliary intake passage is opened toward the spark plug, and the exhaust recirculation passage is extended in contact with an inner wall of the main intake passage. and the tip of the recirculation passage is opened toward the opposite side of the spark plug.

In the drawing, 1 is the engine body, 2 is the piston inside, 3
indicates a combustion chamber on its upper surface; a relatively lean air-fuel mixture, for example, a lean air-fuel mixture close to the ignition limit, is fed into the combustion chamber 3 from an external carburetor 4 through a main intake passage 5 and an intake valve 6 at its downstream end.
It is supplied via a valve boat 7 whose opening and closing is controlled by a valve boat 7, and is ignited by a spark plug 8 on one downstream side (on the left side in the drawing).

In the drawings, reference numeral 9 indicates an exhaust gas recirculation passage branched from an exhaust passage (not shown) leading to the combustion chamber 3, separating the passage 9 from the inside of the main intake passage 5) and passing the valve boat 7 along it. and its tip 9a opens on the opposite side of the boat 7 from the plug 8 (on the right side in the drawing).

The above-mentioned valve boat has the above-mentioned carburetor 4 as a dual-type main carburetor, and the sub-carburizer 10 for generating a relatively rich air-fuel mixture is arranged in parallel on the negative side of the main carburetor, and this is connected via the sub-intake passage 11. 7
The spark plug 8 described above is guided near the tip 11a of the spark plug 8.
The rich air-fuel mixture supplied through the auxiliary intake passage 11 is diluted by the lean air-fuel mixture on the side of the spark plug 8, improving ignition performance and subsequent combustibility. I did it like that.

FIG. 2 shows a plan view of the main parts thereof, and numeral 12 in the figure indicates an exhaust valve at the upstream end of the exhaust passage.

Although not shown, a known control valve is provided on the upstream side of the exhaust gas recirculation passage 9.

According to the present invention, the intake passage has a main intake passage that supplies a relatively lean air-fuel mixture and a sub-intake passage that supplies a relatively rich air-fuel mixture. Since the combustion chamber is connected to the combustion chamber having the ignition plug, the formation of the combustion chamber is simplified, and since the auxiliary intake passage that supplies a relatively rich air-fuel mixture is opened toward the ignition plug, the ignition is ignited by the ignition plug. The combustion speed of a combustion fire of a rich mixture is slowed down by the relatively lean mixture on the surrounding surface, thereby suppressing the generation of NOx. Since the exhaust gas recirculation passage is extended in contact with the spark plug and its tip is opened toward the opposite side from the spark plug, the exhaust gas recirculation passage can be easily installed without disturbing the flow of the air-fuel mixture in the main intake passage, and the exhaust gas recirculation can be carried out near the spark plug. The ignited air-fuel mixture is supplied to form a three-layer stratified air supply condition, with a relatively rich air-fuel mixture layer on the outside and a relatively thin air-fuel mixture layer on its outer periphery, and the ignited air-fuel mixture undergoes combustion propagation in stages. As a result, it has effects such as being able to significantly reduce the generation of NOx.

[Brief explanation of drawings]

FIG. 1 is a cutaway side view of an example of the device of the present invention, and FIG. 2 is a plan view of the main parts thereof. DESCRIPTION OF SYMBOLS 1... Engine body, 3... Combustion chamber, 5... Main intake passage, 6... Intake valve, 7... Valve boat,
8...Spark plug, 9...Exhaust recirculation passage 9a...
・Tip opening.

Claims (1)

[Scope of utility model registration request] An intake valve controls the opening and closing of the intake passage, which has a main intake passage that communicates with the main carburetor that forms a relatively lean air-fuel mixture, and a sub-intake passage that communicates with the auxiliary carburetor that forms a relatively rich air-fuel mixture. In an exhaust gas recirculation device for an engine, in which an exhaust recirculation passage is provided in the main intake passage, the exhaust gas recirculation passage is connected to a combustion chamber having a spark plug through a valve boat that is connected to the combustion chamber, and the exhaust passage is branched from an exhaust passage and communicated with the main intake passage.
opening toward the spark plug, and extending the exhaust gas recirculation passage in contact with an inner wall of the main intake passage;
An exhaust gas recirculation device for an engine, characterized in that the tip of the recirculation passage is opened toward the opposite side of the spark plug.