JPS5855335B2 - Exhaust gas recirculation device for multi-cylinder engines - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exhaust gas recirculation device for a multi-cylinder engine,
In particular, the present invention relates to an exhaust gas recirculation system for a multi-cylinder engine that has a plurality of independent intake passages each communicating with different cylinders, and in which some of the intake passages are provided with shutter valves.

Generally, in operating conditions where the intake negative pressure is high, such as when the engine is idling or decelerating, the air-fuel mixture filling efficiency becomes low, combustion becomes unstable, and misfires are more likely to occur, resulting in torque fluctuations and There is a problem that a large amount of unburned components such as , HC, etc. are discharged.

As one of the countermeasures for the above-mentioned problems, in a multi-cylinder engine, as disclosed in Japanese Utility Model Publication No. 18342/1983, it is necessary to cut off the air-fuel mixture to some cylinders during operating conditions such as idling or deceleration. However, a shutter valve system has been proposed in which the blocked air-fuel mixture is additionally supplied to other cylinders, thereby increasing the filling efficiency of that cylinder and improving the ignition rate.

By the way, a multi-cylinder engine equipped with such a shutter valve system has a plurality of independent intake passages that communicate with different cylinders, and a part of the exhaust gas from the exhaust system is recirculated to the intake system so that some of the exhaust gas remains in the exhaust gas. When equipping a vehicle with an exhaust gas recirculation system designed to suppress the generation of nitrogen oxides (NOx), there are various problems that need to be solved in order to put it into practical use.

The present invention addresses these problems to be solved, and in particular aims at matching the shutter valve system and the exhaust gas recirculation system, thereby ensuring smooth functioning of the shutter valve system and suppressing NOx in the exhaust gas. The object of the present invention is to provide an exhaust gas recirculation device for a multi-cylinder engine.

That is, when part of the exhaust gas is recirculated to the intake system through the exhaust gas recirculation passage, if the opening of the exhaust gas recirculation passage is opened to the intake passage downstream of the shutter valve, even if the shutter valve is closed, The intake passage downstream of the shutter valve and the other intake passage communicate with each other via the exhaust gas recirculation passage, and the air-fuel mixture collected in the other intake passage passes through the exhaust gas recirculation passage again to the intake passage downstream of the shutter valve. Since the air-fuel mixture flows into the intake passage and is supplied to each cylinder, it fulfills the original function of the shutter valve system, which cuts off the air-fuel mixture to some cylinders and burns the air-fuel mixture only in other cylinders. The problem arises that it is no longer profitable.

For this reason, the present invention provides a communication passage that communicates each intake passage downstream of the throttle valve of a plurality of independent intake passages that communicate with each other, and also provides a shutter downstream of the communication passage of some of the intake passages. In a multi-cylinder engine that is equipped with a valve, and the shutter valve is closed during idling or deceleration, the air-fuel mixture to some cylinders is cut off and the air-fuel mixture is combusted in the remaining cylinders. The exhaust gas recirculation passage for recirculating a part of the exhaust gas of the system is characterized in that the opening of the exhaust gas recirculation passage is opened to the intake passage upstream of the shutter valve.

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

FIG. 1 shows a first embodiment of the present invention, which is an example applied to a two-cylinder engine.

In FIG. 1, 1 and 1B are first and second cylinders, 2 and 2B are independent first and second intake passages that communicate with the first and second cylinders IA and IB, respectively,
In both intake passages 2A, 2B, vents 1J3A, 3B and throttle valves 4A, 4B are arranged in order from upstream, respectively.

Throttle valves 4A and 4 of both intake passages 2A and 2B mentioned above
A communication passage 5 is provided downstream of B for communicating the two first intake passages with the second intake passage 2B, and a first intake passage is provided near the downstream of the communication passage 5 of the two first intake passages. A shutter valve 6 that opens and closes is provided, and the shutter valve 6 is fully opened during normal operation and closed during idling or deceleration.
By closing the first valve downstream of the shutter valve 6,
The two intake passages are blocked to cut off the air-fuel mixture to the first cylinder, and the blocked air-fuel mixture is additionally supplied to the second intake passage 2B via the communication passage 5, so that the air-fuel mixture is completely supplied to the second cylinder. It is configured to combust an air-fuel mixture, and constitutes a so-called shutter valve system.

7 is an exhaust passage connected to the first and second cylinders IA and IB.

Further, reference numeral 8 denotes an exhaust gas recirculation passage that recirculates part of the exhaust gas from the exhaust passage 7 to the intake system, and one end opening 8a of the exhaust gas recirculation passage 8 is opened in the middle of the exhaust passage 7. The other end is the first and second branch passages 9, 10.
The other end opening 9b of the first branch passage 9 opens upstream of the two shutter valves 6 of the first intake passage and preferably downstream of the throttle valve 4A, while the second
The other end opening 10b of the branch passage 10 opens downstream of the throttle valve 4B of the second intake passage 2B.

Reference numeral 11 denotes an exhaust gas recirculation control valve interposed in the middle of the exhaust gas recirculation passage 8 (on the upstream side of the branching part), which is opened during operation that requires exhaust gas recirculation, and controls the exhaust gas recirculation. During unnecessary operation (this is the one that closes).

Therefore, in the first embodiment, during normal operation of the engine, the shutter valve 6 is fully opened as shown by the solid line, so the air-fuel mixture from the first intake passage 2A flows into the first cylinder 1A. The air-fuel mixture from the second intake passage 2B is supplied to the second cylinder 1B, and the air-fuel mixture is supplied to each cylinder IA, I
Combustion of the air-fuel mixture takes place in B, and each cylinder IA, 1
A part of the exhaust gas discharged from B to the exhaust passage 7 is introduced into the exhaust gas recirculation passage 8 and then flows through the first and second branch passages 9.
, 10 respectively, the first and second intake passages 2A,
2B, and the generation of NOx in each cylinder IA and IB is suppressed.

On the other hand, when the engine is idling or decelerating,
Since the shutter valve 6 is blocked as shown by the imaginary line, the two first intake passages downstream of the shutter valve 6 are blocked, and the supply of air-fuel mixture from the two first intake passages to the first cylinder is cut off. On the other hand, this shut-off shutter valve 6
The air-fuel mixture of the two people in the first intake passage upstream is the shutter valve 6.
Since the mixture in the second intake passage 2B is additionally supplied to the second intake passage 2B via the communication passage 5 provided upstream, the entire mixture is supplied to the second cylinder 1B via the second intake passage 2B. As a result, the charging efficiency of the second cylinder 1B increases and the ignition rate improves.

Therefore, it is possible to reduce the emissions of unburned fuel during idling or deceleration, and it is also possible to reduce torque fluctuations.

At this time, by opening the other end opening 9b of the first branch passage 9, which recirculates exhaust gas to the two first intake passages, upstream of the shutter valve 6 for the two first intake passages, the second intake passage 2B The air-fuel mixture from upstream of the shutter valve 6 flows through the second branch passage 10 and the first branch passage 9 to the first intake passage 2.
Even if the air-fuel mixture is supplied to a person, it is only circulated through the communication passage 5 to the second intake passage 2B, and the air-fuel mixture is not supplied to a person in the first cylinder, ensuring the function of the shutter valve system. can do.

In addition, FIG. 2 shows a second embodiment of the present invention, and the same parts as in FIG. This is an example in which the other end opening 8'b of the opened exhaust gas recirculation passage 8 is opened in the middle of the communication passage 5 located upstream from the shutter valve 6.

In the case of this example, the first and second branch passages 9 and 10 as in the first embodiment are not required, and the exhaust gas is recirculated through the communication passage 5 in one exhaust gas recirculation passage 8'. In addition, the distribution of the recirculated exhaust gas is improved, and the structure of the exhaust gas recirculation system can be simplified.

Also in this example, since the other end opening 8'b of the exhaust gas recirculation passage 8' opens to the first intake passage 2A upstream of the shutter valve 6 via the communication passage 5, the shutter valve 6 may not be closed. That is, during idling or deceleration, the air-fuel mixture (including recirculated exhaust gas) to the first cylinder is cut off, and the air-fuel mixture is combusted only in the second cylinder 1B.

Although the above first and second embodiments have described a two-cylinder engine, the present invention is not limited to this.
The present invention is applicable to a multi-cylinder engine that has a plurality of independent intake passages communicating with different cylinders and is equipped with a shutter valve system.

As explained above, according to the present invention, in a multi-cylinder engine that has a plurality of independent intake passages each communicating with different cylinders and is equipped with a shutter valve system, part of the exhaust gas from the exhaust system is recirculated. The opening of the exhaust gas recirculation passage is opened to the intake passage upstream of the shutter valve (this completely blocks the filling of some cylinders and greatly improves the filling efficiency of other cylinders, improving combustibility. The system maintains the original function of the shutter valve system, which is to reduce unburned fuel and torque fluctuations by improving fuel efficiency, while also suppressing NOx in the exhaust gas by recirculating the exhaust gas with the exhaust gas recirculation system. It is something that can be done.

[Brief explanation of drawings]

The drawings illustrate embodiments of the present invention, and FIG. 1 is a schematic configuration diagram showing a first embodiment, and FIG. 2 is a schematic configuration diagram showing a second embodiment. 1A...first cylinder, 1B...second cylinder, 2A...first intake passage, 2B...second intake passage, 4A. 4B... Throttle valve, 5... Communication path, 6... Shutter valve, 7...
・Exhaust passage, 8, 8'...Exhaust gas recirculation passage.

Claims (1)

[Claims] 1. A communication passage is provided downstream of the throttle valve of a plurality of independent intake passages that communicate with different cylinders, and a shutter valve is provided downstream of the communication passage of some of the intake passages, By closing the shutter valve during idling or deceleration, the air-fuel mixture to some cylinders is blocked and the air-fuel mixture is combusted in the remaining cylinders. An exhaust gas recirculation device for a multi-cylinder engine, characterized in that an opening of an exhaust gas recirculation passage through which a portion of gas is recirculated is opened to an intake passage upstream of the shutter valve.