JP2002364462A - Egr device in multicylinder internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To equalize an EGR rate at respective cylinders in a multicylinder internal combustion engine. SOLUTION: In this multicylinder internal combustion engine, a part of exhaust gas is supplied to an intake port through an EGR passage 13. The EGR passage 13 is communicated so that the EGR passage 13 opens at the respective intake ports of the respective cylinders. Valve devices 14a, 14b, 15a, 15b, 16a, 16b, 17a and 17b are provided for controlling opening and closing of respective communication parts. The distribution degree of the respective valve devices is set so that the distribution degree is in proportion to the intake efficiency of the respective cylinders.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in an EGR device for reducing NOx of exhaust gas and suppressing black smoke in a multi-cylinder internal combustion engine.

[0002]

2. Description of the Related Art In internal combustion engines such as gasoline engines and diesel engines, NOx contained in exhaust gas
EGR in order to reduce emissions and suppress the generation of black smoke
(Exhaust gas recirculation) is commonly performed. This is because NOx is likely to be generated when the combustion temperature in the combustion chamber is too high, and black smoke is likely to be generated when the combustion temperature is too low. To control. That is, the combustion temperature in the combustion chamber is controlled by both suppressing the combustion reaction by reducing the amount of oxygen by mixing the exhaust gas and lowering the combustion gas temperature by increasing the heat capacity of CO2 contained in the exhaust gas. can do.

[0003] When the internal combustion engine is a multi-cylinder engine, for example, as disclosed in Japanese Utility Model Laid-Open Publication No. Sho 62-67951, EGR gas inlets to each of the cylinders are set to E.
There has been proposed a technique in which the diameter of the GR gas supply path is configured to gradually increase as the distance from the entrance to the entrance of the GR gas supply path increases, thereby uniformly distributing and supplying the EGR gas amount to each cylinder.

[0004]

However, in a multi-cylinder internal combustion engine, the intake efficiency differs depending on the shape of the intake / exhaust system, and the intake air amount differs for each cylinder. Even if the EGR gas amount is evenly distributed and supplied, the so-called EGR rate, which is the ratio of the EGR gas to the total intake air amount (fresh air + EGR gas), is different. As a result, the NOx of the multi-cylinder internal combustion engine as a whole is There is a disadvantage that the reduction and the suppression of the generation of black smoke cannot be controlled.

An object of the present invention is to equalize the EGR rate for each cylinder in a multi-cylinder internal combustion engine.

[0006]

In order to achieve the above object, according to the first aspect of the present invention, a part of the exhaust gas is converted into EG.
In a multi-cylinder internal combustion engine configured to supply to an intake port via an R passage, the EGR passage is communicated so as to be opened for each intake port of each cylinder, and a valve device that controls opening and closing of each communicating portion is provided. The flow rates of these individual valve devices are set in proportion to the intake efficiency in each cylinder. In the present invention, the flow rate refers to the ratio of the amount of EGR gas flowing through the valve device, and the larger the flow rate, the larger the amount of EGR gas flowing when the valve device is opened. Further, the suction efficiency in the present invention is determined by the shape of the suction and exhaust system,
It refers to the ease with which intake air is introduced from the intake port into the cylinder, and the higher the intake efficiency, the greater the amount of intake air introduced from the intake port into the cylinder.

According to the present invention, since the EGR rate for each cylinder becomes constant, the control for reducing NOx and suppressing the generation of black smoke in the entire internal combustion engine can be performed accurately.

[0008] In the second aspect of the invention, among the valve devices, those which are closer to the intake opening of the intake manifold are set to have a larger flow rate than the other devices.

According to the present invention, a large amount of EGR gas is introduced into a cylinder having a relatively large amount of intake air to introduce an EGR gas.
It is intended to prevent the rate from decreasing and prevent an increase in NOx.

[0010] According to a third aspect of the present invention, in the first aspect of the present invention, the flow rate is set by the size of the opening area of the valve seat.

According to the present invention, the flow rate of each valve device is adjusted by making the size of the opening area of the valve seat proportional to the intake efficiency of each cylinder, so that the adjustment can be performed relatively easily. be able to.

According to the fourth aspect of the invention, the first to third aspects are provided.
In the invention described in any one of the above, all of the valve devices are 1
Opening / closing control is performed simultaneously by two actuators.

According to the present invention, since all the valve devices are connected and controlled to be simultaneously opened and closed by one actuator, the structure is simple and the operation amounts and operation timings of all the valve devices can be made uniform.

According to a fifth aspect of the present invention, in the first aspect of the present invention, the flow rate is set by a magnitude of an opening / closing stroke of the valve.

According to the present invention, the flow rate of the valve device is set by the magnitude of the opening / closing stroke of the valve.
This enables highly accurate control.

According to the sixth aspect of the present invention, the first to fifth aspects are provided.
In the invention described in any one of the above, the number of intake ports per cylinder is plural, and the flow rates of valve devices provided corresponding to the intake ports are different from each other.

According to the present invention, for example, when the flow rates at a plurality of intake ports for each cylinder are different from each other so as to be suitable for forming a swirl, the flow rate of the valve device is correspondingly changed. They can be different from each other.

[0018]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a conceptual diagram showing a configuration of a multi-cylinder internal combustion engine provided with an EGR valve according to the present embodiment. In this embodiment, an example of a four-cylinder internal combustion engine is shown. Each cylinder 1,
A pair of intake ports 1a, 1b, 2a, 2b, 3a, 3b, 4b
a, 4b and exhaust ports 1c, 1d, 2c, 2d, 3
c, 3d, 4c, and 4d are open. Of course, these intake / exhaust ports are provided with valves that are opened and closed at appropriate timings. In the base of the intake manifold 5, in this embodiment, an inflow opening 6 is provided at a deviated position adjacent to the cylinder 1, and the distal end thereof has branched branches 7 a, 7 b, 8 a, 8 b, 9 a, 9 b, 10 a, 1 a.
0b is the intake port 1a, 1b, 2a, 2b, 3a,
3b, 4a, and 4b, respectively. Further, the exhaust manifold 11 has the branched distal end portions at the exhaust ports 1c, 1d, 2c, 2d, 3c, 3d, 4d.
An outlet opening 12 is provided at a position slightly adjacent to the cylinder 2 at the base thereof. An EGR passage 13 is provided between the exhaust manifold 11 and the intake manifold 5 so that a part of the exhaust gas discharged to the exhaust manifold 11 is returned to the intake manifold 5. EGR passage 1
The intake manifold 5 side of 3 has branch pipes 7a, 7b, 8
a, 8b, 9a, 9b, 10a, 10b. And these branch pipes 7a, 7b, 8a, 8b,
Valve devices 14a, 14b, 15a, 15 for opening and closing these communication portions are provided in communication portions to 9a, 9b, 10a, 10b.
b, 16a, 16b, 17a, and 17b are provided. These valve devices 14a, 14b, 15a, 15b, 1
Each of 6a, 16b, 17a, and 17b has a configuration as shown in FIG. 2 in which the region A in FIG. 1 is enlarged. That is, a conical valve seat 19 is formed in the opening 18 that communicates the EGR passage 13 with the branch pipe 7a.
The valve 20 that fits into the valve 9 is arranged to be movable in the direction of arrow B. These valve devices 14a, 14b, 15a, 15
b, 16a, 16b, 17a, 17b each valve 2
Numerals 0 are connected to each other by a connecting rod 21, and an actuator 22 is provided at an end of the connecting rod 21. The opening area S of the valve seat 19 (the opening area of the opening 18) is proportional to the characteristics of each of the cylinders 1, 2, 3, and 4, that is, the intake efficiency that varies depending on the shape of the intake / exhaust system. (Valve device 1
4a, 14b, 15a, 15b, 16a, 16b, 17
a, 17b). In the illustrated embodiment, the intake efficiency of the cylinder 1 closest to the inflow opening 6 is the highest, the intake efficiency of the cylinder 4 which is a dead end where the inflow air is likely to accumulate is the next highest, and the order of the cylinder 2 and the cylinder 3 is higher. Therefore, the opening area S of the valve seat 19 is
Is set. In this embodiment, the opening areas of the two valve devices for each cylinder are set to be equal to each other.

The operation of the present apparatus will be described below. When the internal combustion engine is in operation, the intake air introduced into the intake manifold 5 from the inflow opening 6 is supplied to the branch pipes 7a, 7b, 8
a, 8b, 9a, 9b, 10a, and 10b, are fed into the combustion chambers of the cylinders 1, 2, 3, and 4 via the intake ports 1a, 1b, 2a, 2b, 3a, 3b, 4a, and 4b. Is done. Exhaust gas after combustion is discharged to exhaust port 1
c, 1d, 2c, 2d, 3c, 3d, 4c, 4d, are sent out to the exhaust manifold 11 and the outflow opening 12
Is released to the atmosphere through silencers. Part of the exhaust gas in the exhaust manifold 11 is returned to the intake manifold 5 via the EGR passage 13 (this is referred to as E
GR gas). Here, the stroke amount of the actuator 22 is determined according to the operation state of the internal combustion engine, and the opening degree of the valve 20 corresponding thereto is obtained. EGR passage 13
From the respective valve devices 14a, 14b, 15a, 15b, 16
a, 16b, 17a, and 17b, each branch pipe 7a, 7
The EGR gas introduced into b, 8a, 8b, 9a, 9b, 10a, 10b is sent into the combustion chamber while being mixed with the intake air therefrom. At this time, each valve device 14a, 14
b, 15a, 15b, 16a, 16b, 17a, 17b
The opening area S of the valve seat 19 is proportional to the intake efficiency of each of the cylinders 1, 2, 3, and 4, that is, the valve devices 14a, 14b, 15a, 15b, 16a, 16b,
Since the flow rate of each of the cylinders 17a and 17b is proportional to the intake efficiency of each of the cylinders 1, 2, 3, and 4, even if the intake air amount is different for each cylinder, an EGR amount corresponding to the intake air quantity is appropriate.
Gas is introduced, and EGR is performed between all cylinders.
The ratio (the ratio of the EGR gas amount to the intake amount) becomes equal. Note that, in response to a change in the operating state of the internal combustion engine, EG
Even if the R rate changes, the EGR rates among all cylinders are always equal. Therefore, it is possible to reduce NOx and suppress the generation of black smoke without any difference between the cylinders, whereby the control of the reduction of NOx and the suppression of the generation of black smoke in the entire internal combustion engine can be performed accurately.

The effects that can be expected from the above embodiment will be described below. (1) Since the size of the opening area of the valve seat is set in proportion to the intake efficiency in each cylinder, the EGR rates among all the cylinders are always equal. It is possible to accurately control the suppression of black smoke generation, which can greatly contribute to pollution prevention. (2) Since the valve device is provided at a position where the EGR passage opens at each branch pipe of the intake manifold, that is, at a position which opens at each intake port, responsiveness in a transient state such as when the internal combustion engine is accelerated or decelerated. Is good. (3) All valves of the valve device are connected to each other by connecting rods and are operated simultaneously by one actuator, so that accurate operation is possible and the structure is simplified to reduce costs. Becomes

The present invention is not limited to the above embodiment, but can be implemented as follows. ○ In order to set the flow rate of the valve device, in the above embodiment, it was performed by changing the size of the opening area of the valve seat, but under the condition that the size of the opening area of the valve seat is constant, The operation may be performed by changing the magnitude of the opening / closing stroke amount of each valve so that each valve can be operated independently. This has a feature that the accuracy can be easily increased. In this case, the accuracy can be further changed by adjusting the inclination angle of the valve seat. In the above embodiment, two intake ports and two exhaust ports are provided for each cylinder. However, the number of intake ports and the number of exhaust ports do not need to be the same.
It is also possible to implement even if there are three or more. In the above-described embodiment, the opening areas of the two valve devices for each cylinder are equal to each other. However, more strictly, the opening areas corresponding to the intake efficiencies of the two intake ports of each cylinder are adjusted. The areas may be different, and the flow rates of the valve devices may be different from each other. ○ For example, in order to favor the formation of swirl, when the flow rates at the plurality of intake ports per cylinder are made different from each other, the flow rates of the valve devices are made different from each other correspondingly. Is also good.

[0023]

As described above, according to the present invention, even in a multi-cylinder internal combustion engine having different intake characteristics between the cylinders, the EGR rates in all the cylinders can be always equalized. It is possible to reduce NOx and suppress the generation of black smoke without any difference, and thereby control the reduction of NOx and the suppression of black smoke generation in the internal combustion engine as a whole.
Can be done accurately.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a configuration according to the present invention.

FIG. 2 is an enlarged view of an area A shown in FIG.

[Explanation of symbols]

1, 2, 3, 4 cylinders 5 Intake manifold 6 Inlet openings 7a, 7b, 8a, 8b, 9a, 9b, 10a, 10b
Branch pipe 11 Exhaust manifold 12 Outflow opening 13 EGR passage 14a, 14b, 15a, 15b, 16a, 16b, 17a, 17b
Valve device 19 Valve seat 20 Valve 22 Actuator

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02D 21/08 F02D 21/08 L

Claims (6)

[Claims] 1. A multi-cylinder internal combustion engine in which a part of exhaust gas is supplied to an intake port via an EGR passage.
The EGR passage is communicated so as to be opened for each intake port of each cylinder, and a valve device for controlling the opening and closing of each communication portion is provided. The flow rate of each valve device is proportional to the intake efficiency of each cylinder. An EGR device in a multi-cylinder internal combustion engine, characterized in that the EGR device is set in such a manner. 2. The multi-cylinder internal combustion engine according to claim 1, wherein, among the valve devices, a valve device which is closer to the intake opening of the intake manifold has a larger flow rate than the other devices. EGR device. 3. The EGR device in a multi-cylinder internal combustion engine according to claim 1, wherein the flow rate is set by a size of an opening area of a valve seat. 4. The apparatus according to claim 1, wherein all of said valve devices are simultaneously opened and closed by one actuator.
An EGR device for a multi-cylinder internal combustion engine according to any one of the above. 5. The EGR device in a multi-cylinder internal combustion engine according to claim 1, wherein the flow rate is set by a magnitude of an opening / closing stroke amount of a valve. 6. The system according to claim 1, wherein the number of intake ports per cylinder is plural, and the flow rates of valve devices provided corresponding to the intake ports are different from each other. An EGR device for a multi-cylinder internal combustion engine according to Claim 1.