JPH0523824Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an exhaust gas recirculation device for an engine.

(Prior art) In engines, especially automobile engines,
EGR (exhaust gas recirculation) is commonly used to control exhaust gas.

By the way, in some engines, a long first intake passage and a short second intake passage are provided for each cylinder in order to increase the intake inertia effect as much as possible over the entire engine speed range. There is one that switches the passage (Japanese Patent Publication No.
55-29078). That is, in order to obtain the intake inertia effect, the intake passage is required to be long when the engine is running at low speeds, and it is required to be short when the engine is at high speeds.

Due to the above-mentioned intake inertia effect, there are some devices in which the length of the intake passage is determined by a surge tank defining a chamber. In other words, the surge tank (chamber) is used as an intake pressure wave inversion part, and the length of the intake passage on the downstream side of the surge tank is determined as the length of the intake passage for the intake inertia effect. be.

(Problems to be solved by the invention) As mentioned above, in the case where each cylinder has two intake passages, long and short, and two surge tanks, the first and the second, it is necessary to It is conceivable to curve the long first intake passage and place a surge tank for the second intake passage inside it and cast it in one piece, but the first intake passage may be made longer in order to emphasize low speed. In addition, the chamber volume of the surge tank for the second intake passage is determined by performance, so in the case of integral casting, the surge tank for the first
The partition wall at the intersection of the intake passage and the two surge tanks becomes partially thick, resulting in poor castability. In addition, when performing EGR, it is necessary to reduce the exhaust gas temperature.
Although the EGR passage is long, the surge tank occupies a considerable amount of space, making it quite difficult to install the EGR passage, so some kind of countermeasure is desired in this regard.

Therefore, the purpose of the present invention is to improve the compactness of the intake system for engines that have two long and short intake passages for each cylinder and two surge tanks corresponding to the long and short intake passages. transformation,
It is an object of the present invention to provide an exhaust gas recirculation device for an engine that is easy to manufacture and allows easy and simple routing of passage piping for EGR.

(Means and effects for solving the problem) In order to achieve the above-mentioned object, in the present invention, the first and second surge tanks are integrally molded, and the first and second surge tanks are integrally molded. A partition wall defining both chambers is made to extend in the cylinder arrangement direction, and an EGR passage is formed within this partition wall.

With this configuration, the thick wall portion can be eliminated to equalize the wall pressure, and only one pipe is needed from the exhaust system to the integrally molded surge tank, and this surge tank is connected to each cylinder. Since the surge tank serves as a collection point for the intake passages for the cylinders, the surge tank can distribute and supply EGR gas to each cylinder.

(Embodiments) Examples of the present invention will be described below with reference to the attached drawings.

In FIGS. 1 and 2, reference numeral 1 indicates an in-line four-cylinder engine body. This engine body 1
are each intake port 2 that opens to each cylinder (not shown)
is opened on one side 1a of the engine body 1, and each exhaust port (not shown) is opened on the other side of the engine body 1, which is a so-called cross-flow type.

A surge tank 3 is disposed on one side 1a of the engine body 1. This surge tank 3
extends entirely in the cylinder arrangement direction (direction perpendicular to the plane of the paper in FIG. 1), and is an integrally molded product of the first surge tank 4 and the second surge tank 5. That is,
The surge tank 3, which is made of this integrally molded product, has a partition wall 3a extending in the direction of the cylinder arrangement.
The first chamber 4A for the first surge tank 4 and the second chamber 4A for the first surge tank 4
A second chamber 5 for a surge tank 5 is defined. The second surge tank 5 is arranged at a position slightly lower than the first surge tank 4 and slightly offset in a direction away from the engine body 1.

The first surge tank 4 is connected to each intake port 2 via long first intake passages 6 that are independent from each other. Further, the second surge tank 5 is
It is connected to each intake port 22 via short second intake passages 7 that are independent from each other. The first intake passage 6 includes a passage portion 3b integrally formed with the surge tank 3, and an intake pipe 8 connecting the passage portion 3b and the intake port 2. and,
The first intake passage 6 as a whole extends from the first surge tank 4 in a direction away from one side 1a of the engine main body 1, and then curves downward and is reversed approximately 180 degrees to form the first surge tank 3. The shape is such that it passes through the lower part and reaches the intake port 2, thereby ensuring a sufficient length.

On the other hand, the second intake passage 7 is substantially constituted by a branch pipe 8a branched from the upstream end of the intake pipe 8, and a second surge tank 5 opens downward.
is connected to the lower end surface of. That is, the second surge tank 5 (second chamber 5A) and the branch pipe 8a are configured by effectively utilizing the dead space formed by the first surge tank 4 and the first intake passage 6. .

A shutter valve 9 serving as passage switching means is disposed within the branch pipe 8a. This shutter valve 9 is opened and closed according to the engine speed, and when the engine speed is low, it is closed as shown by the solid line in Figure 1, and when the engine speed is high, it is opened as shown by the dashed line in Figure 1. It is said that

Here, in the embodiment, the intake air is supplied only to the first surge tank 4, and therefore, although not shown, a throttle body incorporating a throttle valve for adjusting the amount of intake air is used. is connected to the end of the first surge tank 4 on the back side in FIG. 1 (the end on the top side in FIG. 2). In addition,
In the figure, 10 is a fuel injection valve, and 11 is a delivery pipe.

Inside the bulkhead 3a of the surge tank 3, there is EGR.
A passage 12 is formed. This EGR passage 12
The partition wall 3a extends along the cylinder arrangement direction because the partition wall 3a extends in the cylinder arrangement direction. And EGR
The exhaust gas is introduced from an inlet 12a formed at the end opposite to the connection end of the throttle body.
The exhaust gas introduced into the EGR passage 12 is supplied into the first surge tank 4 from the throttle body connection side end.

Next, the operation of the above configuration will be explained. First, all intake air is supplied from the first surge tank 4 through the first intake passage 6 and from the intake port 2 to each cylinder. At this time, since the shutter valve 9 is closed when the engine speed is low,
The intake inertia effect occurs because the pressure wave of the intake air is reversed by the first surge tank 4, that is, through the long first intake passage 6.
It is said to be effective in matching at low engine speeds. On the other hand, at high engine speeds, the shutter valve 9 opens, so the inversion part of the intake pressure wave becomes the second surge tank 5 for the second intake passage 7, which has a short passage length. Also, the intake inertia effect will be effective.

Here, the exhaust gas for EGR is from the surge tank 3.
After passing through the EGR passage 12 in the partition wall 3 of
It is supplied via a surge tank 4 and a long first intake passage 6. When passing through the partition wall 3a, the air is sufficiently cooled by the intake air in the surge tank 4 or 5.

In the above embodiments, the case where the second surge tank 5 is configured simply as an intake pressure wave inversion section has been described, but the second surge tank 5 is also connected to the first surge tank 4.
It may also be of a type that supplies intake air separately and independently.

(Effects of the invention) As is clear from the above, the invention has the following effects:
Since a surge tank is provided in each of the long and short intake passages, an effective intake inertia effect can be obtained in both the low and high engine speed ranges, while the two surge tanks are integrally molded. Since the EGR passage is formed in the partition wall portion, it is possible to simplify and facilitate piping for EGR while achieving compactness and improving castability.

In particular, since the two surge tanks are integrally molded, it is easy to install the surge tank itself in the intake passage, and the EGR gas is also sufficiently cooled by the intake air in the surge tank. play.

[Brief explanation of drawings]

FIG. 1 is a side sectional view showing an embodiment of the present invention;
FIG. 2 is a plan view of FIG. 1. 1...Engine body, 2...Intake port, 3...
...Surge tank (integral molded product), 4...First surge tank, 4A...First chamber, 5...Second surge tank, 5A...Second chamber, 6...First
Intake passage, 7...second intake passage, 9...shutter valve, 12...EGR passage.

Claims (1)

[Utility Model Claims] Each cylinder of the engine is connected to a first surge tank that defines a first chamber via a long first intake passage, and is connected to a second surge tank that defines a second chamber via a short second intake passage.
an exhaust gas recirculation device for an engine, characterized in that the exhaust gas recirculation device is connected to a second surge tank defining a chamber, and a passage switching means is provided for closing the second intake passage when the engine is rotating at low speed and opening the second intake passage when the engine is rotating at high speed, the first and second surge tanks are integrally molded with each other, a partition wall defining the first and second chambers is formed to extend in the cylinder arrangement direction, and an EGR passage is formed within the partition wall.