JP6504232B1 - Engine intake system - Google Patents

Abstract

An object of the present invention is to lengthen an intake duct 6 while suppressing an increase in intake resistance. An intake duct (6), a surge tank (7), and a plurality of independent intake passages (8) are provided. The intake duct 6 includes a tank-side passage 6 b extending along the surge tank 7. At the downstream end of the intake duct 6, a downstream end introduction passage 13 for introducing the intake air into the surge tank 7 is provided. A short-circuit communication passage 14 for introducing a part of the intake air from the tank passage 6b to the surge tank 7 is provided on the partition wall 10 separating the tank passage 6b upstream from the downstream end introduction passage 13 and the surge tank 7 ing. [Selected figure] Figure 3

Description

  The present invention relates to an intake system of an engine.

  With regard to the intake passage of the engine, Patent Document 1 discloses a structure in which a surge tank elongated in the cylinder row direction of a multi-cylinder engine and each cylinder are connected by an independent intake passage and an intake inlet is provided at one end of the surge tank. The thing is described. In this structure, intake air is introduced into the surge tank from the intake inlet at one end of the surge tank and distributed to the cylinders.

Patent 4420064

  In general, an intake duct is connected to an intake inlet at one end of the surge tank, and a throttle valve is provided in the intake duct. In the case where the duct length from the throttle valve to the surge tank becomes long, there is a concern that the intake resistance will increase during engine operation where the intake amount increases, as when the throttle is fully opened. With regard to the duct length, for example, when introducing a secondary gas (blow-by gas or EGR gas) downstream of the throttle valve portion of the intake duct, the duct length is increased in order to enhance the mixing property of the intake gas and the secondary gas. It is preferable to make the

  Therefore, the present invention provides an intake system capable of suppressing an increase in the intake resistance of the intake duct, in other words, making the intake duct longer while suppressing an increase in the intake resistance.

  According to the present invention, in order to solve the above problems, the intake duct is provided with a passage along the tank extending along the surge tank, and a communication passage is provided in the partition wall between the passage along the tank and the surge tank.

The engine intake system disclosed herein includes an intake duct, a surge tank into which intake air is introduced from the intake duct, and a plurality of independent intake passages connecting the surge tank and cylinders arranged in parallel in a multi-cylinder engine. Equipped with
The intake duct comprises a tank passage extending along the surge tank,
A downstream end introduction passage provided at the downstream end of the intake duct for introducing intake air from the intake duct to the surge tank;
The tank passage and the surge tank are provided on the upstream side of the downstream end introduction passage, and the partition wall for dividing the surge tank is short-circuited between the tank passage and the surge tank so that part of the intake air flows from the tank passage. A shorting communication passage for introduction into the tank ;
And a secondary gas inlet for introducing a secondary gas into each of the cylinders, which is provided on the upstream side of the communication path for short circuit in the intake duct.
The short circuit communication passage is characterized in that the cross-sectional area of the flow passage is smaller than that of the downstream end introduction passage .

According to this, since the intake duct is provided with the passage along the tank extending along the surge tank, it is easy to secure the duct length necessary for mixing the secondary gas and the intake while avoiding the upsizing of the intake device become. That is, when the intake amount is small, the intake air is more likely to be introduced into the surge tank from the downstream end introduction path by passing through the passage along the tank by inertia rather than dropping to the surge tank from the short circuit communication path having a small flow passage cross section. , Ensuring the mixing of the secondary gas and the intake air is facilitated. Thus, in the engine operating range where the intake amount increases, intake air is introduced from the downstream end introduction passage of the intake duct to the surge tank, and a part of intake air is a communication passage for short circuit upstream of the downstream end introduction passage. Since it is introduced into the surge tank through, the increase in intake resistance is suppressed.

  In one embodiment, the short circuit communication passage is provided with a slit extending in the longitudinal direction of the tank passage formed in the partition wall.

  According to this, since the intake air is gradually introduced into the surge tank from the upstream end side (the upstream end side along the tank passage in the longitudinal direction) of the slit toward the downstream end side, it is advantageous for suppressing the increase in intake resistance. . Further, in the case of the slit, for example, the channel cross-sectional area per unit length in the longitudinal direction becomes smaller even if the total channel cross-sectional area is the same as compared with the short channel communication channel of the round hole. Therefore, according to the slit, it is easy to prevent the intake air from unintentionally dropping into the surge tank, that is, it becomes easy to set the amount of withdrawal of the intake air from the middle of the intake duct to the surge tank.

In one embodiment, the upper northern link along path extends straight in the cylinder row direction,
The short circuit communication passage extends straight from the passage along the tank toward the surge tank.

  According to this, since the passage along the tank is extended in the cylinder row direction, it becomes easy to secure the necessary duct length while avoiding the enlargement of the intake system. And since the passage along the tank is straight, the intake resistance is reduced. Therefore, the intake air passes through the passage along the tank by inertia and is more easily introduced into the surge tank from the downstream end introduction passage than through the short-circuit communication passage. Accordingly, since the intake air (fresh air) is mixed with the secondary gas while flowing along the tank passage, the mixing property is improved.

  On the other hand, when the engine is operating at high speed or high load, the amount of intake air increases, and a portion of the intake air is introduced from the communication passage for short circuit into the surge tank. In this case, since the short circuit communication passage extends straight from the tank passage to the surge tank, the intake air can pass through the short circuit communication passage, and therefore, the increase in intake resistance is suppressed.

  In one embodiment, a circulation communication passage is provided on the upstream side of the short circuit communication passage for circulating a part of the intake air from the surge tank to the air intake duct.

  According to this, a part of the intake air introduced into the surge tank is circulated to the intake duct, so even if the intake air is introduced into the surge tank without being sufficiently mixed with the secondary gas, the intake air is released by the circulation. It is possible to mix the secondary gas.

  In one embodiment, the circulation communication passage obliquely intersects the intake duct so as to approach the intake duct from the surge tank as it approaches the intake duct.

  According to this, when intake air flows through the intake duct by inertia, it becomes difficult to deviate toward the circulation communication passage. That is, the intake air is prevented from flowing into the surge tank from the recirculation communication passage, which is advantageous for the intake air recirculation.

  In one embodiment, the opening along the tank side of the communication path for short circuit and the secondary gas inlet of the secondary gas inlet are separated in the longitudinal direction of the air intake duct, but the air intake duct When viewed in the longitudinal direction, the intake ducts are arranged to face each other in the radial direction of the intake duct.

  In other words, the short circuit communication passage is opened in the wall surface of the passage along the tank at a portion of the wall surface of the intake duct opposite to the secondary gas inlet of the intake duct and straight down to the downstream side in the intake flow direction.

  According to this, when the secondary gas introduced into the intake duct from the secondary gas introduction part flows along the wall surface of the intake duct, it reaches the opening of the short circuit communication path. Therefore, the intake air introduced into the surge tank from the communication passage for short circuit has a shorter moving distance (mixing distance) from the secondary gas introduction part than the intake air introduced into the surge tank from the downstream end introduction path. By setting the positional relationship between the secondary gas inlet and the opening of the short circuit communication path, it is easy to be introduced into the surge tank together with the secondary gas. That is, even if the intake air flows into the surge tank from the short circuit communication path without being sufficiently mixed with the secondary gas, the intake air tends to contain the secondary gas.

  Therefore, it is possible to prevent intake air with a low secondary gas concentration from flowing into the surge tank from the short circuit communication passage, and in turn, introduction of intake air with a low secondary gas concentration from the surge tank into each cylinder. For example, when introducing the EGR gas into the intake air as the secondary gas, it is possible to avoid that the EGR gas concentration of the air-fuel mixture in the cylinder becomes unstable (combustion control by EGR, trouble with exhaust gas purification) .

  In one embodiment, the short circuit communication passage is formed in the partition wall such that intake air is introduced to the surge tank in a direction away from the opening of the independent intake passage opened to the surge tank. .

  According to this, even if the intake air does not sufficiently mix with the secondary gas and flows into the surge tank from the communication passage for short circuit, it flows in the direction away from the opening of the independent intake passage. You can earn the flow distance until it flows into the Thus, it is advantageous for mixing of the intake air and the secondary gas.

According to the present invention, the intake duct includes a tank passage extending along the surge tank, and a downstream end introduction passage for introducing intake air from the downstream end of the intake duct to the surge tank, and an upstream side of the downstream end introduction passage. And a shorting communication passage for introducing a part of the intake air from the tankside passage into the surge tank, provided on the partition wall separating the surge tank and the passage along the tank, and upstream of the shorting communication passage in the intake duct. Since the short circuit communication passage has a flow passage cross-sectional area smaller than that of the downstream end introduction passage, it is necessary for mixing the secondary gas and the intake while avoiding the enlargement of the intake device. This makes it easy to secure a proper duct length, and in the engine operating range where the intake quantity increases, the increase in intake resistance is suppressed by the short circuit communication path, which is advantageous for suppressing the deterioration of fuel consumption.

The figure which shows the drive system of FR car typically. The front view which looked at the intake system of the engine from the engine side. The front view which removes the inner member which forms the same intake device, and shows the same intake device. AA sectional view taken on the line of FIG. 2. BB sectional drawing of FIG. CC sectional view taken on the line of FIG. The DD sectional view taken on the line of FIG. The EE sectional view taken on the line of FIG.

  Hereinafter, an embodiment for carrying out the present invention will be described based on the drawings. The following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the invention, its applications or its uses.

  In the drive system of an FR vehicle (front engine / rear drive vehicle) schematically shown in FIG. 1, 1 is a multi-cylinder engine, 2 is a transmission, and 3 is a propeller shaft. The engine 1 is a multi-cylinder engine having a plurality of cylinders arranged in parallel, and includes an intake device 4 for supplying intake air to each cylinder.

  The present embodiment relates to an intake system of an engine of an FR vehicle, but the present invention can also be applied to an FF vehicle (vehicle of front engine and front drive).

<Configuration of Intake Device>
As also shown in FIG. 2, the intake system 4 includes a plurality of intake ducts 6 each having a throttle valve 5, a surge tank 7 into which intake air is introduced from the intake duct 6, and a plurality of surge tanks 7 connecting the cylinders of the engine 1. The independent intake passage pipe 9 which forms the independent intake passage 8 of An EGR valve 21 described later is fixed at the upper center of the independent intake passage pipe 9. An EGR pipe 22 is connected to the EGR valve 21 for circulating a part of the exhaust gas of the engine 1 as an EGR gas (secondary gas) to the intake system.

  As shown in FIG. 3, the intake duct 6 extends from the side of the surge tank 7 straight toward the cylinder in the cylinder row direction from the side of the surge tank 7, and continues to the surge from the upstream passage 6a. A downstream tank passage 6b is provided, which extends straight along the upper side of the tank 7 in the same direction. The passage 6 b along the tank and the surge tank 7 are separated by the partition wall 10.

  As shown in FIG. 4, the intake duct 6, the surge tank 7, and the independent intake pipe 9 of the intake system 4 basically have three members, that is, an inner member 11A, an intermediate member 11B and an intermediate member disposed on the engine body side. It is formed by joining the outer member 11C.

  The inner member 11A, as shown in FIG. 5, forms the upstream side passage 6a of the intake duct 6, and also forms the tip of the independent intake passage pipe 9 joined to the cylinder head of the engine 1. Further, the inner member 11A together with the intermediate member 11B forms the tank side passage 6b which is the downstream side passage of the intake duct 6, and also forms the surge tank 7 together with the intermediate member 11B.

  The intermediate member 11B, as described above, forms the tank passage 6b and the surge tank 7 together with the inner member 11A, and the independent intake passage pipe 9 extending from the surge tank 7 to the distal end of the independent intake passage pipe 9 The main pipe portion is formed together with the outer member 11C.

  As shown in FIGS. 3 to 5, the partition wall 10 for partitioning the tank passage 6b and the surge tank 7 has an inner side wall 10a projecting outward from the inner member 11A and an outer side wall 10b projecting inward from the intermediate member 11B. It is composed of

  As shown in FIGS. 3 and 5, a downstream end introduction passage 13 for introducing the intake air from the intake duct 6 to the surge tank 7 is provided at the downstream end of the intake duct 6 (the end downstream of the partition wall 10). There is. The downstream end introduction passage 13 is an upper end surface of the downstream side of the partition wall 10 and a side wall of the surge tank 7 on one side in the cylinder row direction (a wall of the inner member 11A and the intermediate member 11B on the downstream end side of the intake duct 6). It is formed between.

  As shown in FIGS. 4 and 5, the tank passage 6b and the surge tank 7 are short-circuited between the inner wall 10a and the outer wall 10b constituting the partition wall 10 so that part of the intake air is surged from the tank passage 6b. A short circuit communication passage 14 for introduction into the tank 7 is formed. The short-circuit communication passage 14 has a flow passage cross-sectional area smaller than that of the downstream end introduction passage 13.

  In the present embodiment, the shorting communication passage 14 is a slit extending in the longitudinal direction of the passage 6b along the tank. Further, the inner side wall 10a and the outer side wall 10b are not connected, and the short circuit communication path 14 extends over the entire length of the partition wall 10 (the entire length in the longitudinal direction of the passage along the tank). Further, as shown in FIG. 4, the short-circuiting communication passage 14 extends straight from the tank passage 6 b toward the surge tank 7, and is a direction away from the opening 8 a of the independent intake passage 8 opened to the surge tank 7. It extends in the direction of

  The inner side wall 10a and the outer side wall 10b may be joined. In this case, a short circuit communication passage may be provided in a part of the partition wall in the longitudinal direction of the passage 6b along the tank. Moreover, the communication path for short circuit is not limited to the slit shape, but may be formed by one or more holes. When the shorting communication passage is formed by a plurality of holes, it is preferable that the plurality of holes be aligned in the longitudinal direction of the passage 6b along the tank.

  As shown in FIGS. 3 and 5, on the upstream side of the short circuit communication passage 14, a circulation communication passage 15 for circulating a part of the intake air from the surge tank 7 to the air intake duct 6 is provided. The recirculation communication passage 15 is formed between the upstream end face of the partition wall 10 and the upper portion of the side wall (the wall of the inner member 11A and the intermediate member 11B) of the surge tank 7 on the other side in the cylinder row direction. .

  The upstream end surface of the partition wall 10 and the upper portion of the side wall of the surge tank 7 on the other side are inclined toward the downstream side of the intake duct 6 as the intake tank 6 is approached from the surge tank 7. That is, the recirculation communication passage 15 obliquely intersects the intake duct 6 so as to approach the downstream side of the intake duct 6 as it approaches the intake duct 6 from the surge tank 7. The circulating communication passage 15 has a flow passage cross-sectional area smaller than that of the downstream end introduction passage 13.

  As shown in FIG. 3, in order to introduce the EGR gas into each cylinder of the engine 1 on the upstream side of the communication passage 14 for short circuit in the intake duct 6 and further on the upstream side of the communication passage 15 for reflux. The EGR gas introduction unit (secondary gas introduction unit) 23 is provided. The EGR passage from the EGR valve 21 to the EGR gas introduction unit 23 will be described.

  The EGR passage is, as shown in FIG. 6, a first passage 24 extending from the EGR valve 21 through the center two independent intake passages to the intake duct 6, and as shown in FIG. A second passage 25 extends upstream along the outer wall of the intake duct 6, and an EGR gas introduction portion 23 is provided at an end of the second passage 25. The EGR gas introduction portion 23 protrudes into the intake duct 6.

  The first passage 24 is formed by the intermediate member 11B and the outer member 11C. The second passage 25 is formed by a bulging portion having a semicircular cross section and bulging outward, which is formed on the intermediate member 11B, and a lid member 26 fitted to the opening of the bulging portion. The cover member 26 is provided with an EGR gas introduction unit 23.

  As shown in FIG. 8, the EGR gas introducing portion 23 is an EGR gas introducing port 23 a, 23 b opened vertically on the upper surface and the lower surface of the tip end portion positioned at the central portion (central portion in the radial direction) of the intake duct 6. Is provided. As described above, the EGR gas introduction unit 23 is disposed upstream of the short-circuit communication passage 14 in the intake duct 6. Therefore, the opening 14a on the tank passage 6b side of the short-circuit communication passage 14 and the EGR gas inlets 23a and 23b are separated in the longitudinal direction of the intake duct. However, as shown in FIG. 8, the downward EGR gas inlet 23 b and the opening 14 a of the short-circuit communication passage 14 are mutually up and down in the radial direction of the intake duct 6 when viewed in the longitudinal direction of the intake duct 6. They are arranged to face each other.

  As shown in FIG. 3, FIG. 5 and FIG. 8, the throttle valve 5 is a butterfly type, and the shaft 5b of the valve body 5a is horizontal.

<Operation and effect of the embodiment>
Since the EGR gas introducing portion 23 is separated from the throttle valve 5 on the downstream side of the intake duct 6, dew condensation on the throttle valve 5 and freezing of the valve body 5a can be avoided.

  If this point is explained, if the EGR gas introduction part 23 is provided immediately downstream of the throttle valve 5, since the negative pressure is large immediately downstream, moisture in the EGR gas tends to condense on the valve body, the valve body 5a, etc. When the outside temperature is low, it tends to cause freezing. If the valve body is warmed with engine cooling water in order to avoid freezing, the intake air is constantly heated, which is disadvantageous for improving the fuel efficiency.

  On the other hand, in the embodiment, since the EGR gas introducing portion 23 is provided at a portion distant from the throttle valve 5 on the downstream side, dew condensation on the valve body 5 and the like can be avoided, Because the pressure also decreases, condensation on the inner wall surface of the intake duct 6 is also suppressed. Further, since it is not necessary to heat the throttle valve 5, the fuel consumption can be improved.

  As described above, when the intake duct 6 is directly connected to the side wall of the surge tank 7 without providing the passage 6b along the tank when the EGR gas introducing portion 23 is separated from the throttle valve 5 downstream, the EGR gas introducing portion The distance from the point 23 to the surge tank 7 becomes short, and the mixing property of the EGR gas and the intake air is deteriorated. On the other hand, it is conceivable to increase the distance from the EGR gas introduction portion 23 to the surge tank 7, that is, to increase the mixing distance of the EGR gas, by separating the throttle valve 5 from the surge tank. However, in that case, the entire intake system becomes large, and the layout of the engine and engine-related parts in the engine room of the automobile becomes difficult.

  On the other hand, in the embodiment, since the passage 6b along the tank is provided in the intake duct 6, it is easy to secure an appropriate mixing distance from the EGR gas introduction unit 23 to the surge tank 7. In this case, although the combined volume of the surge tank 7 and the passage 6b along the tank is somewhat increased in order to secure the necessary capacity of the surge tank 7, the intake duct 6 is greatly protruded from the surge tank 7 to secure the mixing distance. Also, the layout of engine related parts etc. is good.

  On the other hand, by providing the passage 6b along the tank in the intake duct 6 as described above, the distance through which the intake air flows from the throttle valve 5 to the surge tank 7 becomes long, so there is a concern about an increase in intake resistance. In particular, when the intake air amount increases due to the change in the engine operating condition, the large intake resistance is disadvantageous for the improvement of the engine output.

  On the other hand, in the embodiment, since the upstream side passage 6a and the passage along the tank 6b constituting the intake duct 6 are straight, it is advantageous for suppressing the increase in intake resistance. Thus, a short circuit communication passage 14 is provided to short the tank passage 6 b and the surge tank 7. Therefore, in a scene where the intake air amount is large (a high engine speed or high load operating region), the intake air is introduced from the downstream end introduction passage 13 of the intake duct 6 to the surge tank 7 and a part of the intake is a tank It is introduced into the surge tank 7 from the passage 6b through the short circuit communication passage 14. As a result, the increase in the intake resistance is suppressed by the short circuit communication passage 14, so that the deterioration of the engine output can be avoided.

  Further, since the shorting communication passage 14 has a slit shape, intake air is gradually introduced from the upstream end side to the downstream end side in the longitudinal direction of the tank passage 6b of the shorting communication passage 14 into the surge tank 7 This is advantageous for suppressing the increase in intake resistance since the

  On the other hand, the amount of EGR gas introduced is larger in the low-low-low-load or medium-speed / medium-load operating range than in the high-speed or high-load operating range. At this time, if the amount of EGR gas which passes from the tank passage 6b to the surge tank 7 through the short circuit communication passage 14 increases, the mixing of the intake air and the EGR gas becomes disadvantageous.

  On the other hand, since the amount of intake air is not so large in the low-rotation low-load to medium-rotation middle-load operation range, the amount of EGR gas which passes from the short circuit communication passage 14 to the surge tank 7 does not increase so much. That is, since the passage 6b along the tank extends straight, the intake air is more likely to be introduced into the surge tank 7 from the downstream end introduction passage 13 through the passage 6b along the tank by inertia rather than falling into the short circuit communication passage 14. Become. Therefore, the mixing property of the EGR gas and the intake air is not significantly reduced by the short circuit communication passage 14.

  Further, in the case of the slit-like short circuit communication passage 14, it is possible to reduce the flow passage cross-sectional area per unit length in the longitudinal direction. Therefore, it is possible to prevent the intake air from unintentionally dropping into the surge tank 7 unintentionally from the short circuit communication passage 14.

  In the above embodiment, even when the intake air passes from the short circuit communication passage 14 to the surge tank 7, the intake gas tends to contain the EGR gas.

  This point will be described. As shown in FIG. 8, the downward EGR gas inlet 23 b of the EGR gas inlet 23 and the opening 14 a of the short circuit communication passage 14 are separated in the longitudinal direction of the intake duct 6 as viewed in the longitudinal direction. When you are in a relationship facing each other up and down. That is, the EGR gas inlet 23 b opens downward, and the opening 14 a of the short circuit communication passage 14 opens on the lower wall surface side of the intake duct 6. Further, the shaft 5b of the valve body 5a of the throttle valve 5 is horizontal.

  Accordingly, in the state where the valve body 5a of the throttle valve 5 is rotated by a predetermined angle and opened, the intake air mainly flows downstream along the upper wall surface and the lower wall surface of the intake duct 6. On the other hand, since the EGR gas inlets 23a and 23b are opened upward and downward, the EGR gas introduced from the EGR gas inlets 23a and 23b is an intake air flowing along the upper wall surface and the lower wall surface of the intake duct 6. It is easy to mix in

  Then, as described above, since the opening 14a of the short circuit communication passage 14 is opened on the lower wall side of the intake duct 6, it is introduced from the EGR gas inlet 23b which is directed downward, and the EGR gas is As it flows along the lower wall surface of the intake duct 6, it reaches the opening 14a of the short circuit communication passage 14. Therefore, the intake air is introduced into the surge tank 7 from the short-circuit communication passage 14 in a state where the EGR gas is mixed.

  That is, the intake air passing through the short-circuit communication passage 14 to the surge tank 7 is likely to be mixed with the EGR gas although the moving distance (mixing distance) from the EGR gas introducing portion 23 is short. In other words, it is possible to prevent intake air having a low EGR gas concentration from flowing into the surge tank 7 from the short circuit communication passage 14 and, in turn, preventing intake air having a low EGR gas concentration from being introduced from the surge tank 7 to each cylinder. Accordingly, it is possible to prevent the EGR gas concentration of the air-fuel mixture in the cylinder from becoming unstable (combustion control by EGR, trouble in exhaust gas purification).

  Moreover, the short-circuit communication passage 14 extends straight from the passage 6 b along the tank toward the surge tank 7 and in a direction away from the opening 8 a of the independent intake passage 8. Therefore, since the intake air mixed with the EGR gas flows in the direction away from the opening 8 a of the independent intake passage 8, it is possible to increase the flow distance until flowing into the independent intake passage 8 in the surge tank 7. Thus, it is advantageous for mixing of the intake air and the EGR gas.

  In the embodiment, the circulation communication passage 15 is provided upstream of the short circuit communication passage 14. Therefore, a part of the intake air introduced into the surge tank 7 is circulated to the intake duct 6 by the circulation communication passage 15. Therefore, the mixing property of the intake air and the EGR gas when the intake flow rate is small can be enhanced.

  Here, the recirculation communication passage 15 obliquely intersects the intake duct 6 so as to approach the downstream side of the intake duct 6 as the surge tank 7 approaches the intake duct 6. Therefore, when the intake air flows through the intake duct 6 by inertia, it is less likely to deviate toward the circulation communication passage 15. That is, the recirculation communication passage 15 functions effectively for the recirculation of intake air.

DESCRIPTION OF SYMBOLS 1 engine 4 intake system 5 throttle valve 6 intake duct 6b passage along tank 7 surge tank 8 independent intake passage 8a opening of independent intake passage 10 partition wall 13 downstream end introduction passage 14 communication passage 14a for short circuit opening 15 communication passage for short circuit 15 circulation Communication passage 21 EGR valve 23 EGR gas inlet (secondary gas inlet)
23b EGR gas inlet (secondary gas inlet)

Claims (7)

An intake system for an engine comprising: an intake duct; a surge tank into which intake air is introduced from the intake duct; and a plurality of independent intake passages connecting the surge tank and cylinders arranged in parallel in a multi-cylinder engine.
The intake duct comprises a tank passage extending along the surge tank,
A downstream end introduction passage provided at the downstream end of the intake duct for introducing intake air from the intake duct to the surge tank;
The tank passage and the surge tank are provided on the upstream side of the downstream end introduction passage, and the partition wall which divides the surge tank is short-circuited between the tank passage and the surge tank so that part of the intake is from the tank passage to the surge tank A shorting passage for introduction into the
And a secondary gas inlet for introducing a secondary gas into each of the cylinders, which is provided on the upstream side of the communication path for short circuit in the intake duct.
The intake system for an engine according to claim 1, wherein the communication passage for short circuit has a flow passage cross-sectional area smaller than that of the downstream end introduction passage . In claim 1,
An intake system for an engine, comprising: a slit extending in a longitudinal direction of the passage along the tank formed in the partition wall as the communication passage for short circuit. In claim 1 or claim 2,
On the northern link along the passage extends straight in the cylinder row direction,
The intake system for an engine according to claim 1, wherein said communication passage for short circuit extends straight from said passage along said tank toward said surge tank. In claim 3,
An intake system for an engine, comprising: a recirculation communication passage provided upstream of the short circuit communication passage for circulating a part of the intake air from the surge tank to the intake duct. In claim 4,
The intake air of an engine characterized in that the recirculation communication passage obliquely intersects the air intake duct so as to approach the air intake duct from the surge tank toward the downstream side of the air intake duct. apparatus. In any one of claims 3 to 5,
The opening on the passage side along the tank of the communication path for short circuit and the secondary gas introduction port of the secondary gas introduction part are separated in the longitudinal direction of the intake duct, but viewed in the longitudinal direction of the intake duct. An intake system for an engine, wherein the intake duct is disposed so as to face each other in a radial direction of the intake duct. In any one of claims 3 to 6,
The short circuit communication passage is formed in the partition wall so that intake air is introduced into the surge tank in a direction away from the opening of the independent intake passage opened in the surge tank. Engine intake system.

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