JP3528517B2 - Engine exhaust gas recirculation system - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine exhaust gas recirculation device (EGR device) for improving fuel efficiency or exhaust performance by recirculating exhaust gas.

[0002]

2. Description of the Related Art In recent years, during normal operation in which no output is required, interest in the environment has increased. Therefore, part of exhaust gas is introduced into an intake system with the aim of reducing CO ₂ or NOx emissions by improving fuel efficiency. Various return exhaust gas recirculation systems (EGR systems) have been proposed.

As a conventional exhaust gas recirculation system for an engine, for example, an example of FIG. 34 (Japanese Utility Model Publication No. 3-114563), an example of FIG. 35 (Japanese Utility Model Publication No. 3-114564),
The example of FIG. 36 (Japanese Patent Laid-Open No. 8-218949) and the like are known.

In FIG. 34, EGR gas from the gas introduction passage 1 is introduced into the intake pipe 2 through two gas guide grooves 3 provided around the intake pipe 2 and two openings 4 horizontally opposed to each other. Then, the fresh air and the EGR gas are mixed. In the structure of FIG. 35, an annular passage 6 for introducing EGR gas is formed on the outer circumference of the intake pipe 5, and the EGR gas is introduced through the plurality of holes 7 connecting the wall surface of the intake pipe 5 and the annular passage 6. By introducing into the inside, fresh air and EGR gas are mixed. All of these are aimed at reducing variations in the exhaust gas recirculation rate between the cylinders.

In FIG. 36, a second surge tank 12 is provided in the intake passage 10 downstream of the first surge tank 11, and an EGR gas introducing portion 13 is arranged in the second surge tank 12. . By introducing the EGR gas into the second surge tank 13 at a position distant from the throttle valve 14 in this way, the deterioration component (deposit) of the exhaust gas is prevented from adhering to the throttle valve 14.

[0006]

However, in these conventional exhaust gas recirculation devices, the EGR to the intake pipe is
It cannot be said that the gas introduction part is in the optimum position and direction.

For example, as shown in FIG. 35, only the EGR gas is introduced through the hole 7 provided in the wall surface of the intake pipe 5, or
As shown in FIG. 4, just by introducing the EGR gas from the opening 4 facing in the horizontal direction, the EGR gas and the fresh air cannot be mixed well. Further, in the case of FIG. 35, the flow state of the fresh air by the throttle valve greatly affects the mixing of the EGR gas and the fresh air and the deposit adhesion to the throttle valve. Further, as shown in FIG. 36, in the case where the EGR gas is introduced into the second surge tank 13, it is difficult to evenly distribute the EGR gas from the surge tank 13 to each cylinder.

Therefore, when a large amount of EGR is carried out, the mixing of the EGR gas and the fresh air becomes insufficient, and as a result, the EGR rate among the cylinders varies, which deteriorates the stability of the engine and reduces emissions. It leads to increase and deterioration of fuel efficiency. Further, except for the one shown in FIG. 36, there is a concern that the control accuracy of the intake air amount may be deteriorated due to the deposit formation on the throttle valve.

The present invention has been made in view of the above-mentioned problems of the prior art, and its object is to improve the variation of the exhaust gas recirculation rate among the cylinders and prevent the engine exhaust gas recirculation device from depositing on the throttle valve. To provide.

[0010]

According to a first aspect of the present invention, an intake system having a throttle valve interposed is provided upstream of an intake pipe having a branch pipe connected to each cylinder and a collector, and an external return passage is provided from the exhaust system. In an exhaust gas recirculation device for an engine that introduces EGR gas into an intake pipe at the rear of the throttle valve of the intake system and upstream of the collector via the EGR gas, the EGR gas introduction port to the intake pipe of the external recirculation path is closed when the throttle valve Only at the rear positions of both free ends, are arranged from the circumferential tangential direction of the intake pipe cross-section to open in a cross-flow type with the inflow directions facing each other, and a predetermined downstream angle with respect to the fresh air flow direction of the intake pipe. In addition to having it , the fresh air flow of the intake pipe
The angle of the EGR gas inlet toward the downstream is
From the position where the EGR gas blows out into the pipe as a base point,
One pin of the crane winding generated inside the intake pipe at the flow direction angle
Set the C position so that it does not reach the inlet of the most upstream branch pipe.
It

A second invention is the EG according to the first invention.
A guide case for projecting the R gas inlet into the intake pipe is provided.

A third aspect of the invention is the fuel cell system according to the first or second aspect of the invention, in which the EGR gas inlet is formed in an oval cross section.

According to a fourth aspect of the present invention, in the first to third aspects, the cross-sectional area of the EGR gas introducing port on the forward tilting free end side of the throttle valve is smaller than that of the EGR gas introducing port on the rearward tilting free end side. Enlarge.

In a fifth aspect based on the first to fourth aspects, auxiliary air is introduced instead of EGR gas from the EGR gas introduction port on the rearward tilted free end side of the throttle valve.

[0015]

According to a sixth aspect of the present invention, in the first to fifth aspects, the opening area of the EGR gas introduction port is set to the maximum velocity of the fresh air passing through the throttle valve and the EG from the throttle valve axis.
It is set according to the distance to the R gas inlet and the EGR gas blowing speed corrected by the opening shape of the EGR gas inlet.

In a seventh aspect based on the first to sixth aspects, when the intake pipe including the throttle chamber has a bend along a plane orthogonal to the throttle valve axis with respect to the collector, The position of the EGR gas inlet is corrected according to the bending angle.

[0018]

According to the first aspect of the invention, the main flow of fresh air and the EGR gas passing through both free end sides of the throttle valve are mixed by the spiral flow (spiral flow) in the circumferential downstream direction of the intake pipe. Promotes mixing, and a large amount of EGR
Even in the case of the rate, the variation in the EGR rate among the cylinders can be sufficiently reduced, and the fuel efficiency and the exhaust performance can be improved. In addition, the EGR gas does not enter the reverse flow region downstream of the throttle valve, and deposit formation on the throttle valve can be prevented. Spa from the gas inlet to the most upstream branch pipe inlet
A certain distance of the air flow is secured, and the entire intake pipe circumference
Mixing of fresh air and EGR gas facilitates mixing
Even if a large amount of EGR rate is advanced, EGR between each cylinder is advanced.
It is possible to sufficiently reduce the variation in the rate. In addition, the throttle bar
It is possible to sufficiently prevent the formation of deposits on the lube.

According to the second aspect of the invention, the main flow passing through both the free end sides of the throttle valve in the guide case is guided to the spiral flow in the circumferential downstream direction of the intake pipe, so that the fresh air and the EGR gas are mixed. Since the mixing can be strengthened, the mixing can be further promoted, and the variation in the EGR rate among the cylinders can be sufficiently reduced even under a large amount of EGR rate. Further, since the bending of the flow toward the center of the intake pipe due to the collision between the fresh air and the EGR gas is eliminated and the EGR gas does not enter the reverse flow region, the deposit formation on the throttle valve can be sufficiently prevented.

According to the third aspect of the invention, since the gas inlet can be arranged near the throttle valve where the reverse flow region in the intake pipe is large and the main flow regions on both free end sides of the throttle valve are narrow, the branch pipe inlet of the uppermost flow can be arranged. Since the spiral flow up to is extended and the mixing time of fresh air and EGR gas can be extended, its mixing is promoted and even under a large amount of EGR rate,
It is possible to sufficiently reduce the variation in the EGR rate between the cylinders. In addition, it is possible to sufficiently prevent deposit formation on the throttle valve.

According to the fourth aspect of the present invention, since the area of the gas introduction port of the larger main flow region is increased, the EGR gas does not enter the reverse flow region and the deposit formation on the throttle valve can be sufficiently prevented. .

According to the fifth aspect of the present invention, the spiral flow for mixing the fresh air and the EGR gas is strengthened and the mixing thereof is further promoted. Therefore, even under a large amount of EGR rate, the EGR rate between the cylinders is increased. Can be sufficiently reduced. Further, since the auxiliary air is introduced from the gas introduction port on the rearward free end side of the throttle valve, EGR gas does not enter the reverse flow region from the narrow main flow region, and deposit formation on the throttle valve can be sufficiently prevented.

[0023]

According to the sixth aspect of the present invention, the EGR gas blowing speed is prevented from stalling due to the collision between the fresh air main flow and the EGR gas, and the spiral flow can be stably ensured. Therefore, the fresh air and the EGR gas can be secured. Mixing is promoted and a large amount of E
Even under the GR rate, it is possible to sufficiently reduce the variation in the EGR rate among the cylinders. In addition, the bending of the EGR gas flow toward the center of the intake pipe due to the collision is eliminated, and the EGR gas is discharged to the reverse flow region.
Since gas does not enter, deposit formation on the throttle valve can be sufficiently prevented.

According to the seventh aspect of the invention, since the gas inlet can be arranged in the intake pipe having the bent portion in accordance with the shape of the reverse flow region in the intake pipe, the same as in the first to seventh aspects of the invention. ,
The mixing of the fresh air and the EGR gas is promoted, and the variation in the EGR rate among the cylinders can be sufficiently reduced even when the EGR rate is large. Further, the EGR gas does not enter the reverse flow region, and the deposit formation on the throttle valve can be sufficiently prevented.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.
However, the underlying technology will be explained first.

1 to 3 show a technology as a premise , 20 is an engine, 21 is an intake manifold, and 22 is an exhaust manifold.

The intake manifold 21 includes an intake pipe 23,
A throttle valve 27 is provided in a throttle body 26 connected to the upstream side of the intake pipe 23, which is composed of a collector 24 having a predetermined volume following the intake pipe 23 and a branch pipe 25 connected from the collector 24 to each cylinder of the engine. It

The exhaust manifold 22 comprises a branch pipe 28 connected to each cylinder of the engine, and an exhaust pipe 30 in which the branch pipes 28 are assembled.

An EGR passage (exhaust gas recirculation passage) for recirculating a part of engine exhaust gas to the intake system from the exhaust pipe 30.
31 is branched, and the EGR passage 31 is branched into two passage portions 32 and 33 from the middle and is connected to the intake pipe 23 behind the throttle valve 27 of the intake system and upstream of the collector 24.

The gas inlet 34 of one of the passage portions 32 has a rearward tilted free end 2 of the throttle valve 27 in the closed state.
At the rear position of 7a, the gas inlet 35 of the other passage portion 33 is also in the closed state when the throttle valve 2 is closed.
7 is opened at the rear position of the forward tilted free end 27b.

In this case, the gas inlets 34 and 35 are provided in the circumferential tangential direction of the cross section of the intake pipe 23 and are opened in a cross-flow type with the inflow directions facing each other, as shown in FIGS. Is formed downstream of a predetermined angle θ (lead angle) with respect to the fresh air flow direction of the intake pipe 23.

The gas inlets 34 and 35 may be formed in opposite directions.

Next, the operation will be described.

FIG. 4 shows a normal operating range and an EGR range represented by the engine speed and the throttle opening. The region in which the EGR is used in the normal operation region is a region excluding a high load region near full throttle opening and a low load region near idle.

FIGS. 5 and 6 show the flow downstream of the throttle valve 27 in the intake pipe 23. In contrast to the main flow passing through the opening of the throttle valve 27, the reverse flow region where the flow circulates on the back surface of the throttle valve 27. Exists. The size of this backflow region depends on the throttle opening, as shown in FIG. The backflow forms of the high load region and the low load region are shown in FIGS. 8 and 9.

The influence of the EGR introduction position A on the physical phenomenon in the intake pipe 23 will be described with reference to FIGS.

First, as shown in FIG. 10, from the downstream side of the backflow region, E
When GR is introduced horizontally, the EGR gas is sandwiched by the main flow that passes through both free end sides of the throttle valve 27 and cannot diffuse, and is allowed to flow downstream in the shortest time, so deposits can be prevented, but mixing with fresh air The condition is bad. When EGR is horizontally introduced into the reverse flow region near the throttle valve 27 as shown in FIG. 11, the EGR gas directly hits the throttle valve 27, which causes deposit formation.

As shown in FIG. 12, EGR is provided near the tip of the reverse flow region.
When the engine is horizontally introduced, it is easily affected by the fluctuation of the engine load state due to the throttle opening, and the mixed state of the EGR gas and the fresh air and the deposit prevention are not stable. Especially in the case of a large amount of EGR, the phenomenon becomes remarkable.

When EGR is introduced into the intake pipe 23 from above and below as shown in FIGS. 13 and 14, the mixed state of EGR gas and fresh air due to the influence of the backflow region, and the performance relating to the deposit prevention are shown in FIGS. It is similar to horizontal introduction. In the case of FIG. 13, the EGR gas becomes a nonuniform flow, and the mixed state with fresh air deteriorates. In the case of FIG. 14, it easily changes depending on the magnitude of the EGR flow velocity.
In the case of a strong flow velocity across the main flow passing through both free end sides, the deposit formation becomes strong, and in the case of a weak flow velocity, the flow becomes uneven and the mixed state with fresh air deteriorates.

The relationship between the mixed state of EGR gas and fresh air and the formation of deposits for these reverse flow regions is shown in FIG.

From the above knowledge, the requirements for satisfying both promotion of mixing of EGR gas and fresh air and prevention of deposit are as follows.

No backflow basin is used.

Maintain a sufficient residence time of EGR gas.

The mainstream of fresh air that causes uneven flow, that is, the entire mainstream that passes through both free end sides of the throttle valve 27, is mixed.

From this point of view , as shown in FIGS. 15 to 17, the EGR gas is supplied to both free ends 2 of the throttle valve 27.
Mixing is performed with the main flow (upper main flow, lower main flow) passing through the 7a, 27b side and the spiral flow in the circumferential downstream direction of the intake pipe 23.

That is, the throttle valve 27 is in a position rearward of the rearward-reclined free end 27a of the throttle valve 27 when one gas inlet port 34 is closed, and the throttle valve 27 when the other gas inlet port 35 is also closed. Are provided at positions rearward of the forward tilted free ends 27b of the intake pipe 23 in the circumferential tangential direction of the cross-section and have a cross-flow type opening that faces the inflow direction and a predetermined angle θ with respect to the fresh air flow direction of the intake pipe 23. Since it is formed downstream, the mainstream velocity of fresh air is the highest,
Both free ends 2 of the throttle valve 27 where no backflow region occurs
The fresh air and the EGR gas are merged at the rear positions of 7a and 27b, and the fresh air and the EGR gas form a spiral flow in the circumferential downstream direction of the intake pipe 23 and are mixed.

As a result, the residence time of the EGR gas becomes much longer than that of the conventional one. Further, due to the union of the fresh air with the main flow, the non-uniform flow factor is eliminated, and the spiral flow to the downstream promotes the diffusion from the outer periphery to the center of the intake pipe 23.

Further, the EGR gas does not enter the reverse flow region downstream of the throttle valve 27, and the deposit formation on the throttle valve 27 is prevented.

Therefore, the mixing of the EGR gas and the fresh air can be promoted, the variation of the EGR rate between the cylinders can be improved, and the prevention of deposit can be achieved at the same time.

18 and 19, the moving distance (residence time) of EGR gas to the inlet of the most upstream branch pipe 25 and EGR
When indicating the cylinders distribution variation rate rate for conventional, the moving distance of the EGR gas by scan Pairaru flow becomes remarkably long, cylinder distribution variation rate of the EGR rate becomes sufficiently small.

[0052] Further, FIG. 20, by the showing a state of the EGR introduction location and deposits formation, introducing the E GR from both free ends 27a of the throttle valve 27, 27b side (upper and lower) in FIG. 21, deposit Formation is sufficiently prevented.

As a result, even under a large amount of EGR rate, variations in the EGR rate among the cylinders can be sufficiently reduced, and fuel consumption and exhaust performance can be improved. Further, it is possible to prevent the influence of the formation of the deposit on the control accuracy of the intake air amount.

FIG . 28 illustrates the first embodiment.
The EGR gas guide in the direction of the fresh air flow in the intake pipe 23.
The downstream angle θ (lead angle) of the inlet (see Fig. 2)
Based on the EGR gas blowing position into the trachea 23,
Cranes generated on the inner circumference of the intake pipe 23 at the downstream angle θ
Winding 1 pitch (lead) position is the most upstream branch pipe 25 pieces
It is set so that it does not reach the mouth. Therefore,
Spiral from the gas inlet to the most upstream branch pipe 25 inlet
A certain distance of flow is secured, and the entire circumference of the intake pipe 23
Mixing of fresh air and EGR gas facilitates mixing
Even if a large amount of EGR rate is advanced, EGR between each cylinder is advanced.
It is possible to sufficiently reduce the variation in the rate. Also, of course,
Sufficiently prevent deposit formation on the rottle valve 27
Wear. 22 to 24 show the second embodiment, in which the gas inlet ports 34 and 35 of the EGR are connected to the guide case 40.
Is projected into the intake pipe 23.

In this case, the guide case 40 is fitted into the pilot hole of the gas inlet provided in the intake pipe 23, and the tip side thereof is projected to near the center line of the intake pipe 23 orthogonal to the gas inflow direction of the guide case 40. It

By this guide case 40, the main flow (upper main flow, lower main flow) passing through both free ends 27a, 27b of the throttle valve 27 is guided to the spiral flow in the circumferential downstream direction of the intake pipe 23.

Therefore, since the mixing of the fresh air and the EGR gas can be strengthened, the mixing thereof is further promoted, and the variation in the EGR rate among the cylinders can be sufficiently reduced even under the large EGR rate. Further, since the flow of the flow toward the center of the intake pipe 23 due to the collision between the fresh air and the EGR gas is eliminated and the EGR gas does not enter the reverse flow region, the deposit formation on the throttle valve 27 can be sufficiently prevented.

FIGS. 25 and 26 show the third embodiment, in which the EGR gas inlets 45 and 46 are formed in an oval cross section. Further, the cross-sectional area of the gas inlet port 46 on the side of the forward tilt free end 27b of the throttle valve 27 is made larger than the cross-sectional area of the gas inlet port 45 on the side of the rear tilt free end 27a.

In this way, the reverse flow region in the intake pipe 23 is large, and the free ends 27a, 2 of the throttle valve 27 are
Since the gas inlets 45 and 46 can be arranged near the throttle valve 27 where the main flow area on the 7b side becomes narrow, the spiral flow up to the inlet of the most upstream branch pipe 25 is extended, and the fresh air and E
The mixing time of the GR gas can be lengthened, so that the mixing thereof is promoted, and the E between the cylinders is increased even under a large amount of EGR rate.
It is possible to sufficiently reduce variations in GR rate. Further, since the shape of the gas inlets 45 and 46 is changed according to the shape of the reverse flow region and the area of the gas inlet port 46 of the larger main flow region is increased, the EGR gas does not enter the reverse flow region and the throttle It is possible to sufficiently prevent deposit formation on the valve 27.

FIG. 27 shows the fourth embodiment.
The EGR gas is introduced from the gas introduction port 51 on the forward tilt free end 27b side of the throttle valve 27, and the auxiliary air is introduced from the gas introduction port 50 on the rear tilt free end 27a side of the throttle valve 27. is there.

In this case, the passage of the gas inlet 50 is connected to the air cleaner upstream of the throttle valve 27.

By doing so, the spiral flow for mixing the fresh air and the EGR gas is strengthened, and the mixing thereof is further promoted. Therefore, even when the EGR rate is large, the variation in the EGR rate among the cylinders is large. Can be sufficiently reduced. Also,
Since the auxiliary air is introduced from the gas introduction port 50 on the side of the rearward tilted free end 27a of the throttle valve 27, EGR gas does not enter the reverse flow region from the narrow main flow region, and deposit formation on the throttle valve 27 is sufficiently prevented. it can.

[0063]

[0064]

FIG. 29 illustrates the fifth embodiment, in which the opening areas of the gas inlets 55 and 56 of the EGR are determined from the maximum passage speed of the fresh air throttle valve 27 and the axis of the throttle valve 27. E corrected by the distance to the gas inlets 55 and 56 and the opening shape of the gas inlets 55 and 56
It is set according to the GR gas blowing speed (inflow speed into the intake pipe 23).

That is, as shown in FIG. 29, the flow velocity of the main stream of fresh air decreases as it goes downstream, but the gas inlets 55, 5
The opening area of the gas introduction ports 55 and 56 including the opening shape is set so that the EGR gas blowing speed from the gas introduction ports 55 and 56 is always higher than the flow velocity of the main flow around 6.

As a result, a sufficient blowing speed of the EGR gas is secured as shown in FIG. 30 to prevent the EGR gas blowing speed from stalling as shown in FIG. 31 due to the collision of the fresh air main flow and the EGR gas. A stable spiral flow can be secured. Therefore, the mixing of the fresh air and the EGR gas is promoted, and the EGR between the cylinders is increased even when the EGR rate is large.
It is possible to sufficiently reduce the variation in the rate. In addition, E
Since the bending of the flow of the GR gas toward the center of the intake pipe 23 is eliminated and the EGR gas does not enter the reverse flow region,
It is possible to sufficiently prevent deposit formation on the throttle valve 27.

FIG. 32 shows the sixth embodiment.
When the intake pipe 23 including the throttle chamber (throttle body 26) has a bend with respect to the collector 24 along a plane orthogonal to the axis of the throttle valve 27, the EGR of the EGR is changed according to the bend angle α. The positions of the gas inlets 60 and 61 are corrected.

In this case, as shown in FIG. 32, when the intake pipe 23 has a bending portion 62 (downward bending portion) with the forward tilted free end 27b side of the throttle valve 27 inward, FIG. As described above, the position of the gas introduction port 61 on the forward tilt free end 27b side of the throttle valve 27 is set to the downstream side,
The position of the gas introduction port 60 on the side of the rearward tilted free end 27a is corrected to the downstream side at a ratio larger than that of the gas introduction port 61.

Further, the intake pipe 23 has a throttle valve 27.
When there is a bent portion (upward bent portion) with the rearward tilted free end 27a side facing inward, as shown in FIG. 33, the gas inlet port 60 on the rearward tilted free end 27a side of the throttle valve 27 depends on the upper bent angle α. The position is corrected to the upstream side, and the position of the gas introduction port 61 on the forward tilt free end 27b side is corrected to the upstream side at a smaller ratio than the gas introduction port 60.

When the intake pipe 23 has a downward bend, the backflow region moves to the rearward tilted free end 27a side of the throttle valve 27, so that the gas introduction ports 60 and 61 are formed relatively downstream to introduce the gas. Move the mouth 60 away from the backflow area.

When the intake pipe 23 has an upward bend, the backflow region moves to the center side of the intake pipe 23. In this case, the gas inlets 60 and 61 are formed relatively upstream so that EG
Increase the moving distance of R gas.

As described above, since the gas inlets 60 and 61 can be optimally arranged for the intake pipe 23 having the bent portion in accordance with the shape of the reverse flow region in the intake pipe 23, as in the above-described respective embodiments. The mixing of the fresh air and the EGR gas is promoted, and the variation in the EGR rate between the cylinders can be sufficiently reduced even under a large amount of EGR rate. In addition, of course, EGR gas does not enter the reverse flow region, and deposit formation on the throttle valve 27 can be sufficiently prevented.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an apparatus .

FIG. 2 is a layout view of a gas inlet.

FIG. 3 is a layout view of a gas inlet.

FIG. 4 is a characteristic diagram showing an EGR region.

FIG. 5 is an explanatory diagram showing a flow downstream of a throttle valve.

FIG. 6 is an explanatory diagram showing a flow downstream of a throttle valve.

FIG. 7 is a characteristic diagram showing a relationship between a throttle opening and a reverse flow region.

FIG. 8 is an explanatory diagram showing changes in a reverse flow region depending on load conditions.

FIG. 9 is an explanatory diagram showing changes in the reverse flow region depending on load conditions.

FIG. 10 is an explanatory diagram showing an EGR gas introduction position and a diffusion state of EGR gas.

FIG. 11 is an explanatory diagram showing an EGR gas introduction position and a diffusion state of EGR gas.

FIG. 12 is an explanatory diagram showing an EGR gas introduction position and a diffusion state of EGR gas.

FIG. 13 is an explanatory diagram showing an EGR gas introduction position and a diffusion state of EGR gas.

FIG. 14 is an explanatory diagram showing an EGR gas introduction position and a diffusion state of EGR gas.

FIG. 15 is an operation explanatory view.

FIG. 16 is an operation explanatory view.

FIG. 17 is an operation explanatory view.

FIG. 18 is an explanatory diagram of an effect of improving variation in EGR rate cylinder distribution.

FIG. 19 is an explanatory diagram of an effect of improving variation in EGR rate cylinder distribution.

FIG. 20 is an explanatory diagram of an improvement effect regarding reduction of deposit formation.

FIG. 21 is an explanatory diagram of an improvement effect regarding reduction of deposit formation.

FIG. 22 is a partial configuration diagram showing a second embodiment.

FIG. 23 is a layout view of gas inlets according to the second embodiment.

FIG. 24 is a layout view of gas introduction ports according to the second embodiment.

FIG. 25 is a partial configuration diagram showing a third embodiment.

FIG. 26 is a layout view of gas inlets according to the third embodiment.

FIG. 27 is a partial configuration diagram showing a fourth embodiment.

FIG. 28 is an explanatory diagram of the first embodiment.

FIG. 29 is an explanatory diagram of the fifth embodiment.

FIG. 30 is an operation explanatory view.

FIG. 31 is an operation explanatory view.

FIG. 32 is a partial configuration diagram showing a sixth embodiment.

FIG. 33 is a characteristic diagram showing an EGR introduction position when the intake pipe is bent.

FIG. 34 is a partial cross-sectional view of a conventional example.

FIG. 35 is a partial perspective view of a conventional example.

FIG. 36 is a schematic configuration diagram of a conventional example.

[Explanation of symbols]

20 engine 23 Intake pipe 24 collectors 25 branch pipe 26 Throttle body 27 Throttle valve 27a Free tilt end 27b Forward tilt free end 30 exhaust pipe 31 EGR passage (exhaust gas recirculation passage) 32,33 passage 34,35 gas inlet 40 guide case 45,46 Gas inlet 50,51 gas inlet 55,56 Gas inlet 60,61 gas inlet 62 bend

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-8-319900 (JP, A) JP-A-8-14108 (JP, A) JP-A-6-173782 (JP, A) JP-A-6- 50216 (JP, A) JP-A-5-223016 (JP, A) Jikho 55-16138 (JP, Y1) (58) Fields investigated (Int.Cl. ⁷ , DB name) F02M 25/07 580 F02D 9/10 F02M 35/10 311

Claims (7)

(57) [Claims] 1. An intake system having a throttle valve interposed upstream of an intake pipe having a branch pipe connected to each cylinder and a collector, and an EGR gas from an exhaust system passing through an external recirculation passage behind the throttle valve of the intake system. In the exhaust gas recirculation device for the engine which is introduced into the intake pipe upstream of the collector, the EGR gas introduction port to the intake pipe of the external recirculation passage is provided only at the rear positions of both free ends of the throttle valve in the closed state. by arranging than the circumference tangential direction of the intake pipe cross-section is opened the flow direction opposite the cross flow type, and the relative fresh air flow direction of the intake pipe Ru to have a predetermined downstream direction angle
EGR gas inlet for both directions of fresh air in the intake pipe
Of the EGR gas blown into the intake pipe
Occurs at the inner circumference of the intake pipe at a downstream angle from the
The 1 pitch position of the crane winding is at the most upstream branch pipe inlet
An engine exhaust gas recirculation device characterized by being set in a range that does not reach . 2. The exhaust gas recirculation device for an engine according to claim 1, further comprising a guide case that projects the EGR gas inlet into the intake pipe. 3. The exhaust gas recirculation device for an engine according to claim 1, wherein the EGR gas introduction port has an oval cross section. 4. The EG on the forward free end side of the throttle valve
The cross-sectional area of the R gas inlet is larger than the cross-sectional area of the EGR gas inlet on the side of the rearward tilted free end.
Exhaust gas recirculation system for engine according to item 1. 5. The EG on the rearward-free end side of the throttle valve
The exhaust gas recirculation device for an engine according to any one of claims 1 to 4, wherein auxiliary air is introduced from the R gas introduction port instead of the EGR gas. 6. The opening area of the EGR gas inlet is
Throttle valve maximum speed and throttle valve shaft
Distance from core to EGR gas inlet and EGR gas inlet
EGR gas blowing speed corrected by the mouth opening shape and
The exhaust gas recirculation device for an engine according to any one of claims 1 to 5, which is set in accordance with the above. 7. An intake pipe including a throttle chamber,
On the surface orthogonal to the throttle valve axis center with respect to the collector
If you have a bend along,
The exhaust gas recirculation device for an engine according to any one of claims 1 to 6, wherein the position of the EGR gas introduction port is corrected according to the degree .