JPH11280562A - Exhaust gas refluxing device of engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a dispersion of EGR(exhaust gas reflux) ratio between each cylinder and to prevent a deposit formation on a throttle valve. SOLUTION: In an exhaust gas refluxing device of an engine 20 in which an EGR gas is introduced to a downstream of a throttle valve 27 of an intake system and to an intake pipe 23 at an upstream of a collector 24, the device is provided with a guide pipe 32 which is connected to an outer reflux passage 31 and inserted into an intake pipe 23 from a predetermined position of a wall of the intake pipe 23 and of which a tip end is projected to a neighborhood of a predetermined position of an inner peripheral surface of the intake pipe 23; and an EGR gas introducing openings 33a, 33b which are formed on a tip end and a base end of a projection in the intake pipe 23 of the guide pipe 32 and opened to an approximately peripheral-tangent direction of a sectional area of the intake pipe 23, respectively. Thereby, a spiral flow of a downstream direction of an inner periphery of the intake pipe 23 is formed and a reduction of a dispersion of an EGR ratio between each cylinder and a prevention of a deposit formation can be compatible.

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 system (EGR system) for improving fuel efficiency or exhaust performance by recirculating exhaust gas.

[0002]

2. Description of the Related Art In recent years, due to the growing interest in the environment,
Reduction of CO ₂ emissions by improving fuel efficiency during normal operation when high output is not required, or N by reducing combustion temperature
Various exhaust gas recirculation devices (EGR devices) that return a part of the exhaust gas to the intake system with the aim of reducing the amount of Ox emission have been proposed.

As a conventional exhaust gas recirculation device, for example, an example shown in FIG. 21 (Japanese Utility Model Laid-Open No. 3-114563), an example shown in FIG. 22 (Japanese Utility Model Application Laid-Open No. 3-114564), and an example shown in FIG. -218949) and the like.

In FIG. 21, the EGR gas from the gas introduction passage 1 is supplied to the intake pipe 2 from two horizontally opposed openings 4 via gas guide grooves 3 provided around the intake pipe 2.
And fresh air and EGR gas are mixed. Also,
22, the fresh air and the EGR gas are mixed by forming an annular path 6 around the intake pipe 5 where the EGR gas is introduced and introducing the annular path 6 into the intake pipe 5. These are all aimed at reducing the variation in the EGR rate between the cylinders.

In FIG. 23, a second surge tank 12 is provided in the intake passage 10 downstream of the first surge tank 11, and the EGR gas introduction unit 1 is provided in the second surge tank.
3 are arranged. By introducing the EGR gas at a position distant from the throttle valve 14 in this manner, a deteriorated portion (deposit) of the exhaust gas is prevented from adhering to the throttle valve 14.

[0006]

[Problems to be solved by the invention]
In a conventional exhaust gas recirculation device, EGR to an intake pipe is performed.
The gas introduction part cannot be said to be at the optimum position and direction, and the following problems occur.

For example, as shown in FIG. 21, only by introducing EGR gas from the opening 4 opposed in the horizontal direction,
Mixing of gas and fresh air cannot be performed well. Also,
22 in which the EGR gas is introduced from the hole 7 provided in the wall of the intake pipe 5 has the EGR gas and the fresh air depending on the operating conditions, that is, the flow of the fresh air and the state of the reverse flow area when the opening of the throttle valve is changed. Is insufficient, or the EGR gas enters the reverse flow region and the deposit increases.
In addition, as shown in FIG.
In the case of introducing gas, it is difficult to distribute the EGR gas from the surge tank 12 evenly to each cylinder.

For this reason, in the conventional apparatus, when a large amount of EGR is performed, mixing of the EGR gas and fresh air becomes insufficient.
As a result, variations occur in the EGR rate between the cylinders, causing deterioration in engine stability, increase in emissions, and deterioration in fuel efficiency. In addition, there is a concern that the formation of the deposit on the throttle valve may cause the throttle valve to stick or the control accuracy of the intake air amount to decrease.

SUMMARY OF THE INVENTION The present invention has been made in view of such conventional problems, and an engine exhaust gas recirculation system for improving the EGR rate variation between cylinders and preventing the formation of a deposit on a throttle valve. To provide.

[0010]

According to a first aspect of the present invention, there is provided an intake system having a throttle valve interposed upstream of an intake pipe provided with a branch pipe and a collector connected to each cylinder. In an exhaust gas recirculation system for an engine, which introduces EGR gas into the intake pipe behind the throttle valve of the intake system and upstream of the collector through the intake pipe, the exhaust gas recirculation device is connected to the external recirculation path and enters the intake pipe from a predetermined position on the intake pipe wall. One guide pipe having a distal end protruding to a predetermined position on the inner peripheral surface of the intake pipe, and formed near the distal end and the proximal end of the projecting portion of the guide pipe in the intake pipe, and open in a direction substantially tangential to a circumferential line of the intake pipe cross section. An EGR gas inlet is provided.

According to a second aspect of the present invention, in the first aspect, the guide pipe is inserted into the intake pipe from an intake pipe wall downstream of the free end of the throttle valve and extends in a direction substantially perpendicular to the throttle axis in a diameter direction of the intake pipe. , The tip of which protrudes to the vicinity of the inner peripheral surface of the intake pipe downstream of the other free end.

According to a third aspect, in the first aspect, the guide pipe enters the intake pipe from an intake pipe wall downstream of a free end of the throttle valve, and a tip of the guide pipe is substantially flush with the throttle shaft. It is characterized by protruding to the vicinity.

According to a fourth aspect, in the first or third aspect, the guide pipe has a shape curved along the inner peripheral surface of the intake pipe.

According to a fifth aspect of the present invention, in the second aspect, the guide pipe is inclined downstream by a predetermined angle from downstream of the forward tilt free end to downstream of the rear tilt free end of the throttle valve. It is.

In a sixth aspect based on the third aspect, the opening area of the EGR gas inlet formed near the distal end of the projection inside the intake pipe of the guide pipe is formed near the base end of the projection inside the intake pipe. Is smaller than the opening area of the EGR gas inlet.

According to a seventh aspect, in the first to sixth aspects, the EGR gas inlet is opened by a predetermined angle in a downstream direction.

An eighth invention is characterized in that, in the first to seventh inventions, the guide pipe has a streamline with a small resistance in a flow direction in the intake pipe.

[0018]

According to the first aspect of the invention, the EGR gas ejected from the EGR gas inlet in the circumferential tangential direction of the cross section of the intake pipe is pressed by the flow of the intake air into the intake pipe in a spiral flow in the inner peripheral downstream direction. (Spiral flow). This allows
Mixing of EGR gas and fresh air is promoted. For this reason, even if the EGR rate is large, the variation in the EGR rate between the cylinders can be reduced, and the fuel efficiency and the exhaust performance can be improved. Further, since the EGR gas is introduced from the circumferential tangential direction of the cross section of the intake pipe, the EGR gas does not directly enter the reverse flow region generated downstream of the back of the throttle valve, thereby suppressing the formation of a deposit on the throttle valve.

According to the second aspect of the present invention, since the EGR gas is introduced into the intake pipe downstream of the free end of the throttle valve, the EGR gas can be carried in the main flow of fresh air having a high flow rate, and the EGR gas and the fresh air can be mixed. Mixing is promoted. Further, since the backflow area becomes smaller downstream of the free end of the throttle valve, the amount of EGR gas flowing into the backflow area can be suppressed, and the formation of deposit can be suppressed.

According to the third aspect, the spiral flow in the downstream direction of the inner circumference of the intake pipe is doubled and strengthened,
Mixing of fresh air and EGR gas is promoted. Also, since the volume of the guide pipe occupying in the intake pipe is reduced, the EGR
The intake resistance at the gas inlet can be reduced.

A high flow velocity is generated at the center of the intake pipe when the throttle valve is fully opened. However, according to the fourth aspect, the guide pipe does not pass through the center of the intake pipe, so that the intake resistance at the EGR gas introduction portion is reduced. The output and the torque at the time of high load can be improved.

According to the fifth aspect of the present invention, the distance from the EGR gas inlet downstream of the free forward end of the throttle valve to the most upstream branch pipe is extended, the residence time of the EGR gas is lengthened, and the EGR gas and fresh air are increased. Is promoted.

The EGR gas introduced from the downstream end of the throttle shaft easily flows into the reverse flow region. However, according to the sixth invention, the opening area of the EGR gas inlet provided downstream of the throttle shaft end is reduced. E introduced from there
The flow rate of the GR gas increases. As a result, high-speed EGR gas is introduced in the circumferential tangent direction of the cross section of the intake pipe.
Gas can be prevented from flowing into the backflow area.

According to the seventh aspect of the present invention, the EGR gas introduction port is opened at a predetermined angle in the downstream direction to prevent the EGR gas from flowing toward the upstream side. Can be suppressed from flowing into the reverse flow region, and thus deposit formation on the throttle valve can be suppressed.

According to the eighth aspect of the present invention, since the guide pipe is streamlined, the intake resistance at the EGR gas introduction section is reduced, and the output and torque of the engine are improved.

[0026]

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

1 to 3 show a first embodiment of the present invention, in which 20 is an engine, 21 is an intake manifold,
22 is an exhaust manifold.

The intake manifold 21 includes an intake pipe 23,
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 20, and a throttle body 26 connected to the upstream side of the intake pipe 23 is supplied to the engine 20. A throttle valve 27 for controlling the amount of air is provided. The throttle valve 27 rotates around the throttle shaft 27c, and the free end that tilts downstream (toward the engine) is the rearward free end 2
7a, and on the contrary, the one inclined to the upstream side is defined as a forward inclined free end 27b.

The exhaust manifold 22 is composed of a branch pipe 28 connected to each cylinder of the engine 20 and an exhaust pipe 30 where the branch pipes 28 are gathered.
An EGR passage 31 (external recirculation passage) for recirculating a part of the exhaust gas of No. 0 to the intake system is branched and formed.

In this embodiment, in this embodiment, a cylindrical guide pipe 32 having a closed end is connected to the EGR passage 31 or is formed integrally with the EGR passage 31, and the guide pipe 32 is inclined forward. Downstream of the free end 27b, the air enters the intake pipe 23 vertically through a hole 34 formed in the intake pipe 23, and its tip protrudes to the vicinity of the inner peripheral surface of the intake pipe 23 downstream of the rearwardly inclined free end 27a. Guide pipe 3
2 is an intake pipe 23 substantially orthogonal to the throttle shaft 27c.
Are arranged in the diametric direction.

Further, as shown in FIG. 3, an EGR gas inlet 33a which opens in the circumferential tangential direction of the cross section of the intake pipe 23 is formed on the side surface near the tip of the guide pipe 32, Guide pipe 3
E that also opens on the two sides in the circumferential tangent direction of the cross section of the intake pipe 23
The GR gas inlet 33b is formed. These EGR gas inlets 33a and 33b are opened in opposite directions at a position approximately 180 ° apart, and are of a cross-flow type in which the directions of the EGR gas flowing into the intake pipe 23 are opposed to each other.

Next, the operation will be described with reference to FIGS.

FIGS. 4 and 5 show the flow of fresh air and EGR gas downstream of the throttle valve 27. FIG. EG introduced into the intake pipe 23 from the EGR gas introduction ports 33a, 33b
R gas is supplied to both free ends 2 of the throttle valve 27.
While being swept away by the high-velocity fresh air main flow (upstream main flow and lower main flow) passing through the gap between 7a, 27b and the intake pipe 23, it is mixed as a spiral flow in the downstream direction along the inner peripheral surface of the intake pipe 23. .

By the way, as shown in FIG. 6, a backflow area in which fresh air flows backward from the downstream to the upstream exists as shown in FIG.
When the distance L between the EGR gas and the EGR gas inlet is short, the EGR gas flows into the reverse flow region, and when the distance L is long, the EGR gas flows as it is as a deflected flow downstream. When the EGR gas flows into the reverse flow region, mixing with the fresh air is promoted. However, the EGR gas hits the throttle valve 27 and deposits on the throttle valve 27 increase. Further, if the gas flows in a downstream direction due to the drift, the EGR gas does not flow into the reverse flow region and the deposit formation can be prevented. However, mixing with fresh air does not proceed, and the variation in the EGR rate among the cylinders increases. That is, the amount of deposit formation and E
There is a trade-off relationship between the GR rate and the inter-cylinder variation as shown in FIG. 7, and it has conventionally been difficult to achieve both reduction in the EGR rate inter-cylinder variation and prevention of deposit formation.

On the other hand, in the present embodiment, as described above, the fresh air and the EGR gas are merged downstream of the free ends 27a and 27b of the throttle valve 27 where the flow velocity of the fresh air main stream is high and the size of the backflow area is small. Since the mixing is performed by forming a spiral flow in the inner circumferential downstream direction of the intake pipe 23, the mixing of the EGR gas and fresh air can be promoted without flowing the EGR gas into the reverse flow area downstream of the throttle valve 27.
The inter-cylinder variation of the GR rate can be reduced, and the formation of a deposit on the throttle valve 27 can be sufficiently prevented. FIG. 8 shows the effect of the present embodiment, and it can be seen from the figure that both the reduction of the EGR rate variation between cylinders and the reduction of the deposit formation, which were difficult in the present embodiment, are compatible.

In the present embodiment, EGR gas inlets 33a and 33b are formed on the guide pipe 32 and are not formed directly in the intake pipe, unlike the conventional apparatus. Since the EGR gas introduction portion is formed by inserting from the hole 34 formed in the EGR 23, the EGR gas introduction portion is formed.
The formation of the gas introduction section is facilitated, and the number of assembling steps and costs can be reduced.

Here, the guide pipe 32 is inserted into the intake pipe 23 from the downstream side of the forward free end 27b. However, the guide pipe 32 enters the intake pipe 23 from the downstream side of the rear free end 27a instead of the forward free end 27b. You may make it enter.

Next, a second embodiment of the present invention will be described.

FIG. 9 shows the EGR gas introduction section. EGR gas inlets 33a, 33b as in the first embodiment
The guide pipe 32 with the hole 3 at the downstream of the free end 27b is tilted forward.
4 is inserted into the intake pipe 23. In order to enhance the effect of improving the EGR performance due to the spiral flow, the EGR gas inlet 33a downstream of the rearward free end 27a is connected to the EGR gas inlet downstream of the frontward free end 27b. The rearward free end 2 is located downstream of the forward free end 27b so as to be downstream of the port 33b.
The guide pipe 32 is inclined in the downstream direction toward the downstream side 7a, and has a predetermined inclination angle φ with respect to a direction perpendicular to the inner wall of the intake pipe 23.

As a result, as shown in FIG. 10, the distance Lb from the throttle shaft 27c of the EGR gas inlet port 33b downstream of the forward leaning free end 27b increases to E downstream of the backward leaning free end 27a.
The distance La is shorter than the distance La of the GR gas inlet 33a from the throttle shaft 27c. As a result, as shown in FIG. 11, the distance from the EGR gas inlet 33b downstream of the free forward end 27b to the most upstream branch pipe 25 is extended, so that the time for mixing the EGR gas and fresh air can be increased, and the collector 24 EGR within
The gas concentration distribution can be made more uniform.

Further, a reverse flow area generated downstream of the back surface of the throttle valve 27 has a rearwardly inclined free end 27 as shown in FIG.
a, the EGR gas does not enter the reverse flow area even if the EGR gas inlet 33b downstream of the forward leaning free end 27b is moved to the upstream side. Deposit formation can be sufficiently suppressed.

Next, a third embodiment will be described.

FIG. 12 shows the EGR gas introduction section. The guide pipe 32 is moved forward from the free end 27b to the intake pipe 23.
The first embodiment is similar to the first embodiment in that the guide pipe 32 is inserted into the inside and the tip thereof protrudes to the downstream of the rearwardly inclined free end 27a. The intake pipe 23 is different in that it has a curved shape (J-shape) along the inner peripheral surface of the intake pipe 23.

At this time, the end of the guide pipe 32 opens in the tangential direction of the cross section of the intake pipe 23 and the EGR gas introduction port 33a
To form An EGR gas inlet 33b is formed on the side surface of the guide pipe 32, which is open in the circumferential tangent direction of the cross section of the intake pipe 23 near the position where the guide pipe 32 enters the intake pipe 23. Therefore, the EGR gas inlet 33
a to the downstream of the rearward free end 27a of the throttle valve 27,
The EGR gas inlets 33b are provided downstream of the free front end 27b at a position approximately 180 ° away from the EGR gas inlets 33b, and the inflow directions of the EGR gas introduced from the respective EGR gas inlets 33a, 33b are opposite to each other. It becomes a flow method.

As a result, as shown in FIG. 13, the EGR gas introduced into the intake pipe 23 becomes a spiral flow, and the mixing of the EGR gas and fresh air is promoted, and the variation in the EGR rate between cylinders is reduced. be able to. Also, since the EGR gas does not directly enter the reverse flow area, the throttle valve 27
The formation of a deposit on the substrate is suppressed.

Further, when the throttle valve 27 is fully open, the flow velocity increases at the center of the intake pipe 23 as shown in FIG. 14, and decreases at the vicinity of the inner peripheral surface of the intake pipe 23, as shown in FIG. By forming the guide pipe 32 in a J-shape along the inner peripheral surface of the intake pipe 23, the intake resistance at the EGR introduction portion can be reduced, and the output and torque under a high load can be improved.

Next, a fourth embodiment will be described.

FIG. 15 shows the EGR introduction section. The third embodiment is different from the third embodiment in that the guide pipe 32 is inserted from the circumferential tangent direction of the cross section of the intake pipe 23 downstream of the forward inclined free end 27b, and has a shape (J shape) along the inner peripheral surface of the intake pipe 23. Although common, the length of the portion of the guide pipe 32 that is curved along the inner peripheral surface of the intake pipe 23 (the protruding portion in the intake pipe) is shorter than in the third embodiment, and the tip of the guide pipe 32 is The difference is that the protruding portion extends substantially on the same plane as the throttle shaft 27c, that is, a position approximately 90 ° away from the insertion position.

At this time, the end of the guide pipe 32 is opened to form an EGR gas inlet 33a. The EGR gas inlet 3 opens in the circumferential tangent direction of the cross section of the intake pipe 23 near the position where the guide pipe 32 enters the intake pipe 23.
3b is formed. Therefore, the EGR gas inlet 33
b to the downstream of the forward tilt free end 27b of the throttle valve 27,
The EGR gas inlet 33a is provided downstream of the throttle shaft 27c at a position approximately 90 ° away therefrom.

Further, since the EGR gas introduced from the EGR gas inlet 33a located downstream of the end of the throttle shaft 27c easily enters a reverse flow region formed downstream of the throttle valve 27, the present embodiment employs a throttle shaft. 2
The opening area of the EGR gas inlet 33a downstream of the end 7c is smaller than that of the EGR gas inlet 33b downstream of the free forward end 27a.

FIG. 16 shows the flow of fresh air and EGR gas downstream of the throttle valve 27.
The EGR gas introduced from a and 33b forms a double spiral flow in the inner circumferential downstream direction of the intake pipe 23. For this reason, the spiral flow is strengthened, the mixing of fresh air and EGR gas is promoted, and the variation in the EGR rate between cylinders is reduced.

Further, since the opening area of the EGR gas inlet 33a is smaller than the opening area of the EGR gas inlet 33b, E that is introduced from the EGR gas inlet 33a is reduced.
The flow rate of the GR gas increases, and the high-speed EGR gas
3 is introduced in the circumferential tangential direction. As a result, the amount of EGR gas entering the reverse flow area can be suppressed, and the throttle valve 2
7 can be sufficiently suppressed.

Further, by reducing the length of the guide pipe 32, the volume occupied by the guide pipe 32 in the intake pipe 23 can be reduced, so that the intake resistance at the EGR gas introduction portion can be suppressed, and the engine output and torque can be reduced. The effect of increasing the number is also obtained.

Next, a fifth embodiment will be described.

FIGS. 17 and 18 show the EGR introduction section. This corresponds to the EGR gas inlet 3 in the first embodiment.
3a and 33b are opened at a predetermined downstream angle θ with respect to the tangential direction of the cross section of the intake pipe 23.

Thus, the EGR gas inlets 33a, 3
The EGR gas introduced from 3b forms a spiral flow in the downstream direction of the inner circumference of the intake pipe 23 and is mixed with fresh air as shown in FIG. 18, but the EGR gas introduction ports 33a and 33b are opened downstream. As a result, the EGR gas does not flow toward the upstream, and does not easily enter a reverse flow region formed downstream of the throttle valve on the back side, so that deposit formation can be suppressed.

As described above, since it becomes difficult for the EGR gas to enter the backflow region, the EGR inlets 33a and 33b can be provided further upstream. EGR gas inlet 3
If the 3a and 33b are provided on the upstream side, the distance from the EGR gas inlets 33a and 33b to the most upstream branch pipe 25 becomes longer, and the mixing of fresh air and EGR gas is promoted.
It is possible to suppress the variation in the rate between cylinders.

Here, in the first embodiment, E
Although the GR gas inlets 33a and 33b have the downstream angle θ, the same effect can be obtained by providing the EGR gas inlets 33a and 33b with the downstream angle θ in other embodiments.

Next, a sixth embodiment will be described.

FIGS. 19 and 20 show the EGR gas introduction section. In the first embodiment, the cross-sectional shape of the guide pipe 32 protruding into the intake pipe 23 is streamlined with a small air resistance in the flow direction in the intake pipe 23 in the first embodiment. In FIGS. 19 and 20, the cross-sectional shape of the guide pipe 32 is long in the intake air flow direction in which the upstream side and the downstream side are sharp. However, other shapes may be used as long as the air resistance is small. By making the guide pipe 32 streamlined in this way, the intake resistance at the EGR gas introduction section can be reduced, and the output and torque of the engine can be improved.

Although the guide pipe 32 is streamlined in the first embodiment, the same effect can be obtained by setting the guide pipe 32 streamlined in other embodiments.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a first embodiment.

FIG. 2 is an explanatory diagram of the EGR gas introduction unit.

FIG. 3 is an explanatory diagram of the EGR gas introduction unit.

FIG. 4 is an explanatory diagram of a spiral flow generated downstream of a throttle valve.

FIG. 5 is an explanatory diagram of a spiral flow.

FIG. 6 is an explanatory diagram of a reverse flow region generated downstream of the back surface of the throttle valve.

FIG. 7 is a characteristic diagram showing a relationship between a variation in an EGR rate between cylinders and an amount of deposit formation.

FIG. 8 is a diagram illustrating effects of the first embodiment.

FIG. 9 is an explanatory diagram of an EGR gas introduction unit according to the second embodiment.

FIG. 10 is an explanatory diagram of an EGR gas introduction unit according to the second embodiment.

FIG. 11 is an explanatory diagram of a spiral flow in the second embodiment.

FIG. 12 is an explanatory diagram of an EGR gas introduction unit according to a third embodiment.

FIG. 13 is an explanatory diagram of an EGR gas introduction unit according to the third embodiment.

FIG. 14 is an explanatory diagram of a flow velocity distribution in an intake pipe.

FIG. 15 is an explanatory diagram of an EGR gas introduction unit according to a fourth embodiment.

FIG. 16 is an explanatory diagram of an EGR gas introduction unit according to the fourth embodiment.

FIG. 17 is an explanatory diagram of an EGR gas introduction unit according to a fifth embodiment.

FIG. 18 is an explanatory diagram of an EGR gas introduction unit according to the fifth embodiment.

FIG. 19 is an explanatory diagram of an EGR gas introduction unit according to a sixth embodiment.

FIG. 20 is an explanatory diagram of an EGR gas introduction unit according to the sixth embodiment.

FIG. 21 is a partial sectional view of a conventional example.

FIG. 22 is a partial perspective view of another conventional example.

FIG. 23 is a schematic configuration diagram of still another conventional example.

[Explanation of symbols]

 Reference Signs List 20 engine 23 intake pipe 24 collector 25 branch pipe 27 throttle valve 27a rearward free end 27b forward free end 27c throttle shaft 31 EGR passage (external recirculation passage) 32 guide pipe 33a, b EGR inlet

Claims (8)

[Claims] An intake system having a throttle valve is provided upstream of an intake pipe having a branch pipe and a collector connected to each cylinder, and an EGR gas is supplied from an exhaust system via an external recirculation passage to a rear side of the intake system throttle valve. And an exhaust gas recirculation device for an engine to be introduced into the intake pipe upstream of the collector, wherein the exhaust gas recirculation apparatus is connected to the external recirculation path, enters the intake pipe from a predetermined position on the intake pipe wall, and has a tip thereof near a predetermined position on the intake pipe inner peripheral surface. One protruding guide pipe; and an EGR gas inlet formed near the distal end and the proximal end of the guide pipe protruding portion inside the intake pipe, and each opening in the direction of a substantially circumferential tangent to the cross section of the intake pipe. An exhaust gas recirculation device for an engine. 2. The guide pipe is inserted into an intake pipe from an intake pipe wall downstream of a free end of a throttle valve, extends in a direction of a diameter of the intake pipe substantially perpendicular to a throttle axis, and has a distal end downstream of the other free end. 2. The exhaust gas recirculation device for an engine according to claim 1, wherein the exhaust gas recirculation device protrudes to near the inner peripheral surface of the intake pipe. 3. The intake pipe according to claim 1, wherein the guide pipe enters the intake pipe from the intake pipe wall downstream of the free end of the throttle valve, and a tip of the guide pipe protrudes near the inner peripheral surface of the intake pipe on substantially the same plane as the throttle shaft. The exhaust gas recirculation device according to claim 1. 4. An exhaust gas recirculation system for an engine according to claim 1, wherein said guide pipe is formed in a curved shape along an inner peripheral surface of an intake pipe. 5. The exhaust gas recirculation of an engine according to claim 2, wherein said guide pipe is inclined downstream by a predetermined angle from downstream of a forward leaning free end to downstream of a rearward free end of a throttle valve. apparatus. 6. An opening area of an EGR gas introduction port formed near a tip of an intake pipe projecting portion of the guide pipe is larger than an opening area of an EGR gas introduction port formed near a base end of the intake pipe projecting portion. The exhaust gas recirculation device for an engine according to claim 3, wherein the exhaust gas recirculation device is small. 7. The exhaust gas recirculation device for an engine according to claim 1, wherein the EGR gas inlet is opened by a predetermined angle in a downstream direction. 8. The exhaust gas recirculation device for an engine according to claim 1, wherein the guide pipe has a streamline shape having a small resistance in a flow direction in the intake pipe.