JPH048296Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an exhaust gas recirculation device for an engine that recirculates a portion of exhaust gas into an intake passage to suppress the generation of _NOx .

[Prior Art] Generally, in an automobile engine, in order to reduce _NOx in the exhaust gas, a portion of the exhaust gas is returned to the intake passage to suppress the combustion temperature. In addition, modern automobiles have a surge tank installed in the intake passage to suppress intake pulsation, and intake air is supplied from the surge tank to each cylinder through intake branch pipes that are branched into the same number of cylinders. There are some things. In this way, in an engine with a surge tank installed in the intake passage,
When exhaust gas is recirculated to the intake passage as described above, a plurality of exhaust gas discharge ports are formed on the other side wall of the surge tank facing the opening of the intake branch pipe,
Normally, a portion of the exhaust gas is distributed to each cylinder via the surge tank.

However, simply by arranging the intake port and the exhaust gas discharge port to face each other, it is difficult to uniformly distribute the exhaust gas led into the surge tank to each cylinder. Various efforts have been made to solve this problem. For example, as shown in the prior art in Japanese Utility Model Application Publication No. 170060/1983, an exhaust gas discharge port and an intake port are arranged opposite each other in a surge tank. There is also a type in which the distance between the branch pipe and the opening is changed for each opposing cylinder.

[Problems to be solved by the invention] However, as shown in the prior art, in the conventional device, the intake port is opened in a direction substantially perpendicular to the opening of the intake branch pipe. is common. In such devices, however, the intake air introduced into the surge tank is often directly supplied to each cylinder from the opening through the intake branch pipe. Therefore, the intake air and exhaust gas are not sufficiently mixed within the surge tank, in other words, the exhaust gas led into the surge tank is non-uniformly supplied to each cylinder. As a result, it becomes difficult to sufficiently suppress the generation of _NOx in each cylinder, resulting in a problem.

The present invention aims to solve the above-mentioned problems regarding the exhaust gas recirculation device.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides an intake port at one end of the surge tank interposed in the intake passage, with the intake port diagonally directed toward one side wall of the surge tank. intake branch pipes for each cylinder that guide the intake air in the surge tank to a plurality of cylinders are opened at different height positions with respect to the inlet, and these intake branch pipes are A plurality of exhaust gas discharge ports are provided on the other side wall of the surge tank facing the opening of the surge tank, and the exhaust gas discharge ports are formed to have a smaller diameter as they approach the introduction port.

[Function] With this configuration, the surge tank interposed in the intake passage has air flowing from the intake inlet opening diagonally toward one side wall of the surge tank toward the inner surface of the one side wall. Intake air will be introduced. The intake air introduced into the surge tank is guided along the one side wall from near the wall surface on the side opposite to the inlet port to near the wall surface of the other side wall facing the one side wall. The cylinders are guided to openings of intake branch pipes for each cylinder, which are opened in the one side wall at different positions.
At this time, exhaust gas is discharged from the exhaust gas discharge port opened in the other side wall, but since the discharge port is formed to have a smaller diameter as it approaches the inlet, the exhaust gas is discharged on the side opposite to the inlet. A large amount of exhaust gas is supplied to the turbulent intake flow that passes near the exit while changing direction, and is mixed with the intake flow, making it possible to distribute the exhaust gas substantially uniformly to each cylinder.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings.

In the figure, reference numeral 1 indicates a surge tank with a rectangular cross section that is installed in the intake passage on the downstream side of the throttle valve, and an inlet 3 for guiding intake air into the surge tank 1 is formed at one end 2 of the surge tank. There is. The introduction port 3 is opened in the center of the square-shaped one end 2 in an oblique direction toward the inner surface 4a of one side wall 4 adjacent to the one end 2 in a horizontal position.

The one side wall 4 is provided with intake branch pipes 5, 6, and 7 for each cylinder for guiding intake air introduced into the surge tank 1 from the introduction port 3 to a plurality of cylinders. The intake branch pipes 5, 6, 7 are integrally formed in the one side wall 4, and the openings 5a, 6a,
7a are formed at equal intervals in the lower part of one side wall 4 at different height positions with respect to the introduction port 3. Outlet ports 5b, 6b, and 7b communicating with the combustion chamber side of each cylinder are opened in an end surface 8a of a flange 8, which is a connecting portion formed at the lower end of the intake branch pipes 5, 6, and 7.

On the other hand, the lower part of the end wall 9 located on the side opposite to the inlet 3 from the upper side of the intake branch pipe 7 and the other side wall 11 facing the openings 5a, 6a, 7a of each intake branch pipe 5, 6, 7. An exhaust gas recirculation passage 12 having a circular cross section is formed in a series of thick columnar parts formed along the lower part. The exhaust gas recirculation passage 12 is connected to the exhaust passage through an exhaust gas recirculation control valve (not shown) and is for guiding a part of the exhaust gas into the surge tank 1, and is provided protruding from the upper side of one of the intake branch pipes 7. Starting end port 1 formed in the protrusion 13
2a, an end wall port 12b formed perpendicular to the tip of the start port 12a, and a terminal port 1 formed perpendicular to the tip of the end wall port 12b.
2c. The outer end of the start port 12a is opened at the end surface of the protrusion 13, and the open end is used as the exhaust gas inlet 14, while the end port 12c has two exhaust gas discharge ports 15, 16. has been formed. That is, both the exhaust gas discharge ports 15 and 16 are connected to the intake branch pipe 5,
It is provided at the lower part of the other side wall 11 facing the openings 5a, 6a, 7a of 6 and 7, and the end wall 9 side which is the upstream side of exhaust gas is a large diameter exhaust gas discharge port 15, and the intake port 3 The side has a small diameter exhaust gas discharge port 16.

According to such a configuration, during engine operation, intake air flows from the inlet 3 to the inner surface 4a of the one side wall 4.
It is introduced into the surge tank 1 toward the side. Then, the intake air introduced into the surge tank 1 gradually descends and is guided to the end wall 9 side so as to follow the inner surface 4a side of the one side wall 4, and changes direction near the corner of the inner surface 9a of the end wall 9. It is dispersed in the surge tank 1 while being disturbed, and finally the openings 5a, 6a, 7a
From there, it is supplied to the combustion chamber of each cylinder via intake branch pipes 5, 6, and 7.

On the other hand, a part of the exhaust gas from the exhaust gas inlet 14 is sequentially guided to the terminal port 12c via the starting port 12a and the end wall port 12b of the exhaust gas recirculation channel 12, and is formed in the terminal port 12c. The exhaust gas is ejected into the surge tank 1 from the exhaust gas discharge ports 15 and 16. At this time, a relatively large amount of exhaust gas is discharged from the large-diameter exhaust gas discharge port 15 opened on the end wall 9 side into the intake air which is disturbed near the inner surface 9a of the end wall 9 and is about to be dispersed into the surge tank 1. Gas is supplied. In addition, the opening 5a of the intake branch pipe 5, etc. can be relatively easily opened as the exhaust gas is discharged.
A small amount of exhaust gas is supplied into the surge tank 1 from the exhaust gas discharge port 16 on the downstream side where it is easily transported to the surge tank 1.

Therefore, with such a configuration, the intake air led into the surge tank 1 from the inlet 3 provided at one end 2 of the surge tank 1 will flow through the end wall present at the other end of the surge tank 1. 9, where it is disturbed and dispersed in the surge tank 1. Therefore, if a large amount of exhaust gas is ejected toward the intake air, which is being disturbed and is about to disperse, the intake air This makes it possible to effectively mix the exhaust gas and the exhaust gas, thereby suppressing local non-uniformity of the exhaust gas within the surge tank 1. Also, along with the discharge, one opening 5a
From the exhaust gas discharge port 16 on the downstream side where exhaust gas is easily carried directly to the side, a smaller amount of exhaust gas is spouted than the large diameter discharge port 15, so that the exhaust gas during intake is prevented from being absorbed. Equilibrium can be particularly reduced.

Note that the present invention is of course not limited to the above-mentioned embodiment. For example, in the above-mentioned embodiment, there are two exhaust gas discharge ports, but there are a plurality of exhaust gas discharge ports whose diameter gradually decreases from the end wall side to the intake port side. It is also possible to form several exhaust gas discharge ports.

[Effect of the invention] According to the invention having the above-described configuration, the intake air and exhaust gas guided into the surge tank can be effectively mixed, so that the intake air and exhaust gas inside the surge tank can be mixed effectively. It becomes possible to suppress local non-uniformity. As a result, the exhaust gas led into the surge tank can be distributed almost uniformly to each cylinder, so the engine exhaust gas recirculation system can effectively suppress the generation of _NOx in each cylinder. can be provided.

[Brief explanation of the drawing]

1 to 3 show an embodiment of the present invention,
Figure 1 is a partially sectional front view of the surge tank, Figure 2
The figure is a partially sectional plan view of the same surge tank, and FIG. 3 is a right side view of the same surge tank. DESCRIPTION OF SYMBOLS 1... Surge tank, 2... One end, 3... Inlet, 4... One side wall, 5, 6, 7... Intake branch pipe, 5a, 6a, 7a... Opening, 9... End wall ,
11...Other side wall, 12...Exhaust recirculation passage, 14...
...Exhaust gas inlet, 15, 16...Exhaust gas discharge port.

Claims (1)

[Scope of utility model registration request] An intake port is formed at one end of the surge tank interposed in the intake passage in an oblique direction toward one side wall of the surge tank, and each side wall is provided with an intake port for guiding the intake air in the surge tank to a plurality of cylinders. Intake branch pipes for each cylinder are opened at different heights relative to the inlet, and a plurality of exhaust gas discharge ports are provided on the other side wall of the surge tank facing the openings of these intake branch pipes. An exhaust gas recirculation device for an engine, characterized in that the exhaust gas discharge port is formed to have a smaller diameter as it approaches the inlet.