JPS60252154A - Suction device for engine - Google Patents

Abstract

PURPOSE:To reduce variations in the distribution of exhaust gas recirculation gas between cylinders so sharply a range, by leading the EGR gas into space between the top of a surge tank and the circumferential surface of an upstream suction passage as well as between the bottom of the surge tank and the said circumferential surface of the upstream suction passage. CONSTITUTION:Plural downstream suction passages 3a-3d are opened in series to a bottom surface 2 of a surge tank 1. An upstream suction passage 5 is projected from a side face 4 of the surge tank 1 to the inside of the tank 1 at the center of a line of these downstream suction passages 3a-3d. An opening of a first EGR passage 7 is set up in a remote spot away from each opening of these downstream suction passages. An opening of a second EGR passage 8 being smaller in a passage area than the first EGR passage 7 is set up in a nearby spot. Thus, variations in the distribution of EGR gas between cylinders are sharply reducible.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an intake system for an engine.

[Prior art]

In recent years, in vehicle engines, from the perspective of exhaust gas countermeasures,
Some of the exhaust gas is returned to the intake system as EGR gas to lower the combustion temperature of the engine and reduce NOx components in the exhaust gas. If the EGR gas is directly refluxed to the intake flow, the EGR gas will be introduced at a relatively high flow velocity in a specific direction within the intake passage, which will impede intake air distribution and cause the EGR gas to be biased against the intake flow. However, there is a problem in that the distribution of EGR gas to each cylinder becomes uneven.

Therefore, conventionally, in order to solve the above-mentioned problems, as shown in, for example, Japanese Utility Model Application Publication No. 55-119346,
A chamber is provided at the BGR opening of the intake passage, and the EG
Some systems have been designed to reduce the flow velocity and directionality of R gas and then use the flow of intake air to distribute EGR gas to each cylinder.

However, in the device described in the above-mentioned conventional publication, because of its structure, the EGR gas was distributed simply by utilizing the intake air flow, and therefore the EGR gas was distributed between the cylinder near the opening of the EGR passage and the cylinder far from the opening. There was still a risk that the distribution of EGR gas would vary.

[Purpose of the invention]

In view of these problems, the present invention aims to provide an engine intake system that can significantly reduce variations in EGR gas distribution between cylinders.

[Structure of the invention]

As a result of intensive research to develop an intake device that can significantly reduce variations in EGR gas distribution, the inventor of the present invention found that
We discovered the following. That is, a surge tank is usually provided at the joint part of the intake manifold from the viewpoint of reducing intake pulsation. In this surge tank, if the openings of each intake manifold with respect to the tank are arranged in series and the intake pipe is made to protrude into the surge tank perpendicularly to the row direction at the sub-center of the intake manifold, the surge There are two narrow spaces between the inner surface of the tank and the outer surface of the intake pipe protrusion, but the flow velocity of the intake air is extremely low at these narrow spaces, so if EGR gas is introduced there, It is believed that the EGR gas can be distributed evenly to both the left and right sides of the intake pipe protrusion, and the inventor of the present invention also confirmed this through experiments.

However, in this case, due to layout considerations, if EGR gas is introduced only into one of the narrowly spaced locations, a problem arises in that the distribution of EGR gas varies between the plurality of intake manifolds on the left or right side. Ta. In other words, if the EGR gas is introduced into the narrowly spaced locations near the opening row of the intake manifold, the distance between the EGR passage opening and the intake manifold opening will have a large effect on the distribution of EGR gas (eg, EGR gas Most of it is introduced into the central intake manifold, and almost none of it is introduced into the outer intake manifolds.On the other hand, contrary to the above, among the narrowly spaced places, there are places far from the opening row of the intake manifold. ) If EGR gas is introduced into the flll and tl, the influence of the intake pipe protrusion on the EGR force distribution will be large, and in the above case, a large amount of EGR gas will be introduced into the outer intake manifold. As a result, the amount introduced into the center intake manifold has decreased.

Therefore, this invention provides an EG
Focusing on the difference in EGR power distribution when R gas is introduced, we opened multiple downstream intake passages in series on the bottom of the surge tank, and installed a surge tank (■) in the sub-center of the downstream intake passage. 1] A first flow intake passage is projected into the surge tank from the surface, and the Im distance between the outer circumferential surface of the upstream intake passage and the inner surface of the surge tank is the narrowest,
The first EGRiJl is located far from the opening force of the downstream intake passage.
The opening of the second EGR J passage, which is smaller than the first EGR passage and has a passage area larger than that of the first EGR passage, is placed close to the opening of the second EGR passage. Introducing this, it is distributed evenly to the left and right by 1-4), and the distribution variation of η between the downstream intake passages on the left or right side is corrected with the EGR gas from the second EGR passage. This is how it was done.

〔Example〕

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

1 to 3 show an intake system for an engine according to an embodiment G of the present invention. The figure shows a roughly rectangular parallelepiped surge tank, and the bottom surface 2 of the surge tank 1
The upstream ends of the first to fourth downstream intake passages 3a to 3d are connected in communication with each other, and are disposed directly in front of each opening IJ, that is, on a straight line extending in the length direction, and the downstream intake passages 3a to 3d are arranged in a straight line extending in the length direction. 3
The downstream end of d is the combustion chamber of each of the first to fourth cylinders (not shown)
will be communicated to).

In addition, the downstream end of the flow intake passage 5 is blindly connected to the center of one side surface 4G of the surge tank 1,
The downstream end of the upstream intake passage 5 is connected to the downstream intake 1Jli[? 3 each
At the sub-centers of a to 3d, the surge tank is parallel to the bottom surface 2 of the surge tank and protrudes toward the surge tank from a direction perpendicular to the direction of the downstream intake passages 3a to 3d.

Further, the surge tank 1 is provided with six EGR passages. The EGR passage 6 is connected to a first EGR passage 7 in the surge tank 1, and a second EGR passage 7 whose minimum area is smaller than the first EGR passage 7. The lower end a of the first EGR passage 7 is located at a position where the distance between the -F surface 9 of the surge tank 1 and the outer peripheral surface of the upstream intake passage 5 is minimum. while the second EGR
The tip opening 8a of the passage 8 is arranged at a position where the distance between the bottom surface 2 of the surge tank 1 and the outer peripheral surface of the upstream intake passage 5 is minimum.

Next, the effect will be explained.

In this device, when the intake air in the upstream intake passage 5 is introduced into the surge tank 1, the intake air is temporarily stored there and then equally distributed to the downstream intake passages 3a to 3d for each cylinder. is introduced into the combustion chamber (see arrow A in Figure 3).

On the other hand, part of the exhaust gas is converted to EGR gas in the EGR passage 6.
When the EGR gas is introduced into the surge tank 1, most of the EGR gas passes through the first EGR passage 7 and reaches the upper surface 9 of the surge tank 1 in the surge tank 1.
and the outer peripheral surface of the upstream intake passage 5, where the flow velocity and directionality are reduced, and then the downstream intake passages 3a to 3d are introduced into the surge tank 1 by the action of the intake air (see arrow A in FIG. 3). This E is then inhaled.
The GR gas is guided to the outer peripheral surface of the upstream intake passage 5 and passes through the first.
There are many downstream intake passages 3a and 3d (see arrow B in FIGS. 1 to 3), and a second downstream intake passage 3a, 3d. a third downstream intake passage 3b;
3c (see arrow C in FIGS. 1-3).

Further, the remaining EGR gas is introduced into the surge tank 1 through the second EGR passage 8, and the opening 8a of the second EGR passage 8 and the second. The distance between the openings of the third downstream intake passages 3b and 3c is the same as the distance between the opening 8a of the second EGR passage 8 and the opening of the first. Fourth
downstream intake passage 3a.

Since it is short compared to the distance between the 3d opening and the 2nd E
EGR gas from the GR passage 8 is mainly distributed and sucked into the second and third downstream intake passages 3b and 3c (see arrows in FIGS. 1 and 2).

The apparatus of this embodiment as described above can provide the following effects.

(i) EGR gas is introduced between the top of the surge tank and the outer circumferential surface of the upstream intake passage, and between the bottom of the surge tank and the outer circumference of the upstream intake passage, so ECR gas is introduced at a location away from the flow of intake air. The flow velocity and directionality of the EGR gas can be reduced by introducing the fuel into the cylinder, and as a result, the EGR gas can be supplied to each cylinder without inhibiting the flow of intake air.

(ii) Since EGR gas is introduced into the sub-center of the first to fourth downstream intake passages, F, GR gas is introduced into the first to fourth downstream intake passages.
．． a second left downstream intake passage; and a third left downstream intake passage. It can be evenly distributed to the fourth right downstream intake passage.

(iii) Since most of the EGR gas is guided and distributed by the outer circumferential surface of the old method intake passage, this also allows the EGR gas to be evenly distributed to the left and right.

(iv) Most of the EGR gas is distributed to the left and right, and this is distributed between the first and second . Or, when distributing to the third and fourth downstream intake passages, the second. The amount of EGR gas introduced into the third downstream intake passage is influenced by the outer peripheral surface of the upstream intake passage. Although the amount introduced into the fourth downstream intake passage is small, since this is corrected by a small amount of EGR gas introduced into the bottom side of the surge tank, all of the first to fourth downstream intake passages The amount of EGR gas introduced can be made equal.

Note that the present invention is not limited to the above embodiments,
Various modifications and changes are possible; for example, the number of downstream intake passages may be a plurality other than four.

〔Effect of the invention〕

As described above, according to the engine intake system according to the present invention, a plurality of downstream intake passages are opened in series at the bottom of the surge tank, and at the sub-center of the downstream intake passage, an upstream passage is opened from the side of the surge tank into the surge tank. The intake passage is made to protrude, and the opening of the first EGR passage is located at a location farthest from the opening of the downstream intake passage among the locations where the distance between the outer circumferential surface of the upstream intake passage and the inner surface of the surge tank is the narrowest, and the opening of the first EGR passage is located at a location close to the opening of the downstream intake passage.
The opening of the second EGR passage is arranged to have a passage area smaller than that of the EGR passage, and most of the IEGR gas is introduced from the first EGR passage and distributed evenly to the left and right, and the distribution that occurs between the downstream intake passage on the left or right side is Since the variation in EGR gas is corrected by the EGR gas from the second EGR passage, the variation in EGR gas distribution can be significantly reduced compared to the conventional device.

[Brief explanation of drawings]

FIG. 1 is a schematic perspective view of an engine intake device according to an embodiment of the present invention, FIG. 2 is a sectional front view of the device, and FIG. 3 is a sectional plan view of the device. 1... Surge tank, 2... Bottom, 3a to 3d...
・Downstream intake passage, 5... Upstream intake passage, 7, 8...
1st ° 2nd EGR passage, 9...Top surface. Patent applicant Ken Hayase, Mazda Motor Corporation agent and patent attorney - Figure 3

Claims (1)

[Claims] (1) A surge tank is provided with a bottom surface in which downstream intake passages that communicate with each of a plurality of combustion chambers are opened in series, and the surge tank is parallel to the bottom surface of the surge tank at the center of the row of downstream intake passages, and An upstream intake passage is provided that protrudes toward the inside of the surge tank from a direction perpendicular to the row direction of the intake passages, and the upper surface of the surge tank parallel to the bottom of the surge tank and the outer periphery of the protruding upstream intake passage are provided. The opening of the first EGR passage is arranged at a position in the surge tank at which the distance between the opening and the first EGR passage is minimum, and the distance between the bottom of the surge tank and the outer peripheral surface of the protruding first flow intake passage is An intake system for an engine, characterized in that an opening of a second EGR passage whose minimum area is smaller than the +-EGR passage is disposed at a minimum position in the surge tank.