JPH0311402Y2 - - Google Patents

Description

[Detailed explanation of the idea] Technical field The present invention relates to an intake system for an internal combustion engine.

BACKGROUND OF THE INVENTION Exhaust gas recirculation (EGR) devices are known in which a portion of exhaust gas is recycled into intake air. In such an EGR device, an EGR passage is integrally formed in the surge tank in order to guide exhaust gas to intake air. Conventionally, the discharge opening of the EGR passage was opened in a direction perpendicular to the direction of intake air flow, and it was believed that this was suitable for evenly distributing the recirculated exhaust gas to each cylinder. Even so, the amount of recirculated exhaust gas varied between cylinders. When the throttle valve suddenly opened from fully closed, a whistling sound was sometimes generated at the discharge opening.

Purpose of the invention The purpose of the invention is to improve the distribution of the recirculated exhaust gas and to eliminate the above-mentioned whistling noise.

Structure of the invention The intake system for an internal combustion engine according to the invention includes a surge tank equipped with a branch pipe that distributes intake air to each cylinder, and an EGR passage that is integrally formed with the surge tank and receives a part of the engine exhaust gas. and the above
At least a portion of the EGR passage, whose wall surface protrudes into the inner surface of the intake air passage at the inlet of the surge tank, intersects with the direction of flow of the intake air and forms a flow path of the intake air passage at the inlet. a specific portion of the EGR passage forming a diaphragm that narrows the cross-sectional area; a discharge opening for the exhaust gas that opens in a part of the downstream side of the wall surface constituting the specific portion of the EGR passage; The engine is characterized in that it includes a protrusion that protrudes from the inner surface of the intake air passage near the exhaust gas discharge opening in the vicinity of the inlet of the tank and has a hole therein for crankcase ventilation.

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

FIG. 1 is a front view of the surge tank 1. FIG. The surge tank 1 is connected to a throttle body (not shown) in which a throttle valve is disposed on the right end surface in FIG. Therefore, the intake air flows from right to left as shown by arrow F. A surge tank 1 shown in FIG. 1 is applied to a four-cylinder internal combustion engine, and branch pipes 2, 3, 4, and 5 are arranged in parallel with respect to the air flow direction. The branch pipe 2 is connected to the NO1 cylinder, and then sequentially to the NO4 cylinder.

The right end portion of FIG. 1 is shown in cross section.
This section is a vertical longitudinal section taken along the line - of FIG. 2, which is a transverse section taken along the line - of FIG. The EGR passage extended from the exhaust pipe via a well-known valve device is connected to the surge tank 1.
It is integrally formed in the surge tank 1 at.
The EGR passage 6 is a hole that opens at the left end in FIG. 1, and this opening can be connected to an exhaust pipe through ducts. The EGR passage 6 extends horizontally from the left end to the right end, and curves vertically upward 6' slightly to the right of the branch pipe 2 in FIG. 1, that is, on the intake air inlet side. The surge tank 1 has, at least in this part, an approximately rectangular external contour as shown in FIG. It is provided along the vertical inner surface of the profiled wall and protrudes inward in a vertical cylindrical shape between the top and bottom of the wall. These walls 7, 8, 9 are integrally molded with the surge tank wall. Discharge opening 10 of EGR passage 6'
is opened toward the downstream side in the intake air flow direction near the top bottom.

On the opposite side of the opening 10 of the EGR passage 6', a hole 11 for crankcase ventilation is formed along the upper bottom of the intake air passage, and the wall forming the hole 11 has a downwardly protruding protrusion. 12. For this reason, the intake air passage along the upper base is narrowed.

Figures 3 and 4 show the results of testing the amount of exhaust gas distributed to each cylinder, and Figure 3 shows the number of rotations.
2000rpm, 180mmHg, Figure 4 is 2400rpm, 120mm
This figure shows the EGR rate depending on Hg conditions.
In the conventional technology, the opening of the EGR passage is indicated by arrow D in Figure 2.
As shown in the figure, a surge tank is used which is opened toward the center of the intake air passage at right angles to the flow direction of the intake air. As seen in FIGS. 3 and 4, the present invention improves the distribution of exhaust gas between cylinders. This has walls 7, 8, 9 on the inner surface of the intake air passage at the entrance part of the intake air passage.
Since the EGR passage 6' and the protrusion 12 having the crankcase ventilation hole 11 therein protrude into the passage at a relatively close position, the intake air passage at the inlet of the surge tank 1 is The EGR passage 6' is narrowed at that point to form a constriction part, and the flow velocity is increased here, and the EGR passage 6' is formed in the intake air flow where turbulence is generated by vortices behind these protruding parts. Exhaust gas flows out in the direction of the flow of intake air from an opening 10 provided in the downstream wall 7, which is one of the walls where the exhaust gas flows. This is thought to be due to the fact that the gas and intake air are better mixed, and the exhaust gas is distributed evenly to all branch pipes instead of having a large amount of exhaust gas flowing only into the airflow towards the branch pipes of a specific cylinder. It will be done.

If there are no protruding parts such as the EGR passage 6' or the protruding part 12, and the exhaust gas is discharged upward and at right angles to the intake air flow as shown by arrow D in FIG. The concentration of exhaust gas in the branch pipe 5 is higher than that in other cases because the air flowing along the upper wall contains a large amount of the exhaust gas. The EGR passage 6' that protrudes into the intake passage and the vortices of the intake air flow generated behind the protrusion 12 that has a hole 11 for crankcase ventilation inside, diffuse into the intake air flow, and each branch pipe. Smoothly adapting to the suction forces from 2, 3, 4, 5, the airflow containing exhaust gas is evenly distributed and the exhaust gas concentration in all branches is averaged.

Effects As explained above, the distribution of EGR exhaust gas between cylinders has improved, and at the same time, the whistling noise has been eliminated. The present invention is characterized in that the constriction part is formed by using the EGR passage that protrudes into the intake air passage in the surge tank and the protrusion for crankcase ventilation. Since it is made of a material, it is advantageous in terms of cost and space.

[Brief explanation of the drawing]

Figure 1 is a front view including a partial cross section of the surge tank according to the present invention, Figure 2 is a cross-sectional view taken along the line - in Figure 1, and Figures 3 and 4 are for different operating conditions. It is a graph of the EGR rate in . 1... Surge tank, 2, 3, 4, 5... Branch pipe, 6, 6'... EGR passage, 10... Discharge opening.

Claims (1)

[Scope of utility model registration request] a surge tank equipped with a branch pipe that distributes intake air to each cylinder; an EGR passage that is integrally formed with the surge tank and receives a portion of engine exhaust gas;
At least a portion of the EGR passage has a wall surface that protrudes into the inner surface of the intake air passage at the inlet of the surge tank, thereby intersecting the flow direction of the intake air and directing the flow of the intake air passage at the inlet. a specific portion of the EGR passage forming a diaphragm that narrows the cross-sectional area of the EGR passage; a discharge opening for the exhaust gas that opens in a part of the downstream side of the wall surface constituting the specific portion of the EGR passage; an internal combustion engine comprising: a protrusion protruding from the inner surface of the intake air passage near the exhaust gas discharge opening in the vicinity of the inlet of the surge tank and having a hole therein for crankcase ventilation; intake device.