KR100412018B1 - Intake line structure of internal combustion engine equipped with egr apparatus - Google Patents

Abstract

The intake system of an internal combustion engine with an EGR device is provided. In order to enable the smooth change of the EGR rate in the cylinder for each stroke, the intake openings 23 of the exhaust from the exhaust passages are formed in each of the intake paths. A flow path is formed at an upstream side of the branch portion 13 branching to each of the cylinders 3A to 3D, and flows from the introduction hole 23 to the intake holes 4A to 4D of the respective cylinders 3A to 3D for each cylinder. The inlet path 9 is formed so that the flow path length of the flow path is inequality in at least two cylinders, and the flow volume is equal or approximately equal between all the cylinders 3A to 3D. do.

Description

Intake system structure of internal combustion engine with EG device {INTAKE LINE STRUCTURE OF INTERNAL COMBUSTION ENGINE EQUIPPED WITH EGR APPARATUS}

The present invention relates to an intake structure of an internal combustion engine with an EGR device.

BACKGROUND ART An exhaust recirculation device (EGR device) for recirculating a part of the exhaust gas from the exhaust to the intake air is known. By providing the EGR apparatus in the internal combustion engine (engine "engine"), it is possible to lower the combustion temperature in the combustion chamber and reduce the production of nitrogen oxides (NOX). However, if the amount of recycled exhaust gas is too large, the amount of air for combustion is insufficient, and graphite is generated in a diesel engine "diesel", and unburned gas is generated in a gasoline engine "gasoline engine".

For this reason, for example, in the case of a diesel engine "diesel engine", during the acceleration, the EGR valve is closed in accordance with the amount of fuel for acceleration, thereby reducing the exhaust rate (EGR rate) in the mixer, and conversely, The ratio is increased to prevent graphite.

However, there is a considerable time delay from the operation of the EGR valve until the EGR rate in each cylinder actually decreases. This time delay is until the response delay from the output of the control signal to the EGR valve until the EGR valve is operated, or until the air (mixer of intake and exhaust) reaches the respective cylinders from the installation position of the EGR valve. Although the delay of the EGR rate is delayed in this manner, the amount of air for combustion is insufficient with respect to the injected fuel amount, and graphite is generated.

Therefore, a technique for calculating the EGR rate of the mixer sucked into the cylinder and limiting the amount of fuel to be injected in accordance with the calculated EGR rate has been proposed.

However, as shown in FIG. 5, the intake air 30 of the general diesel engine "diesel engine" (here, the in-line four-cylinder engine "engine") communicates with the air cleaner "air cleaner" not shown in the drawing and throttles ". throttle " intake pipe 32 "

an intake port "port" (37A to 37D) formed in the "cylender head" 34 and communicating with the intake holes 38A to 38D of the cylinders 39A to 39D, the intake pipe 32 and the intake port "port" It is formed by the intake manifold "manifold" 33 which connects 37A-37D. The intake manifold " manifold " 33 is branched from the cylindrical surge tank " surge tank " 35 and connected to the respective intake ports " ports " 37A-37D. It is formed of branch pipes 36A-36D.

In addition, an EGR device 42 is provided to recycle the exhaust gas from the exhaust passage not shown in the drawing to the intake passage 30. The EGR device 42 is composed of an EGR pipe 44 for communicating the exhaust path and intake air 30, not shown, and an EGR valve 41 disposed in the EGR pipe 44 to control the amount of recirculation of the exhaust gas. The EGR pipe 42 is connected to an EGR guide hole 43 formed downstream of the excretion portion of the throttle "throttle" valve 40 of the intake pipe 32.

According to the above configuration, the air (intake) sucked into the intake pipe 32 via the air cleaner "air cleaner" (not shown) is mixed with the exhaust in the excretion portion of the EGR introducing hole 43 to become a mixer. Flows into the surge tank " surge tank " 35 from the intake pipe 32, and is sucked into each of the cylinders 39A to 39D via the intake ports " PORT " 37A to 37D from the branch pipes 36A to 36D. Done. Therefore, when the EGR valve 41 is operated to change the EGR rate, the EGR rate in each of the cylinders 39A to 39D is equal to the flow volume of the passage from the EGR introducing hole 43 to the intake holes 38A to 38D. Change will be delayed.

At this time, the mixer passes through the passage 45A to the first cylinder 39A, passes through the passage 45B to the second cylinder 39B, passes through the passage 45C to the third cylinder 39C, and The fourth cylinder 39D flows in through the flow passage 45D, but the lengths of the flow passages 45A to 45D are not the same, and the flow volume is not the same. 5, the flow volume of the flow paths 45B and 45C is smaller than the flow paths 45A and 45D.

6 (a) to 6 (h) schematically show changes in the EGR rate in the intake passage 30 from the intake pipe 32 to each of the cylinders 39A to 39D in FIG. It is indicated by. 6 (a) to 6 (h) sequentially show the first to eighth strokes, firstly intake into the first cylinder 39A in the first stroke, and then the third cylinder 39C and the fourth stroke. It is assumed that the cylinder 39D and the second cylinder 39B are sequentially inhaled. Here, the EGR valve 41 is operated so that the flow rate ratio of the exhaust to the total flow rate is 50% in the first stroke, and the EGR valve 41 is operated so that the flow rate ratio of the exhaust is 25% in the second stroke, After the third stroke, the case where the EGR valve 41 is completely closed is indicated. In addition, in the intake air 30 of FIGS. 6 (a) to 6 (h), the black portion represents the exhaust, that is, the EGR rate is 100%, whereas the white portion represents the intake, that is, the EGR rate is 0%. have. In addition, the dark gray portion represents a mixer having an EGR rate of 50%, and the light gray portion represents a mixer having an EGR rate of 25%.

As shown in Figs. 6 (a) to 6 (n), in the second cylinder 39B and the third cylinder 39C having a small flow volume, the EGR rate in the cylinder is controlled by the closing operation of the EGR valve 41. Falls quickly. However, in the first cylinder 39A and the fourth cylinder 39D having a large flow volume, time delay occurs as much as the amount coagulated in the flow path, and the decrease in the EGR rate in the cylinder is slowed down. For this reason, the change of the EGR rate in the case of the whole engine "engine" does not become a smooth change, As shown in FIG. 7, after falling once in the 4th stroke, it rises again in the 5th stroke, After falling from the 6th stroke, it becomes an awkward change rising again from the 7th stroke.

In the case where the EGR rate varies from stroke to stroke, if the amount of fuel to be injected is limited in accordance with the EGR rate in the cylinder as described above, the emission of graphite can be suppressed, but the fuel injection amount also changes, and smooth acceleration cannot be obtained. . On the other hand, in the case of controlling the fuel injection amount so that smooth acceleration can be obtained, graphite is generated in the fifth and seventh strokes in which the EGR ratio rises due to lack of air.

As described above, in the intake system of the conventional engine "engine", even if the EGR rate of the mixer sucked in the cylinder is calculated and the amount of fuel injected is limited according to the EGR rate, the EGR rate does not change smoothly, so smooth acceleration is obtained. There was problem that we could not. In addition, if smooth acceleration is to be obtained without generating graphite, the fuel injection amount must be increased in accordance with the EGR rate of the stroke (the fifth and seventh strokes in the case shown in Fig. 7) where the EGR rate rises. There has been a problem that the acceleration of the fuel is delayed and rapid acceleration cannot be obtained. This problem includes not only the intake system structure of the configuration as illustrated in FIG. 5, but also the type of introducing the exhaust directly into the surge tank "surge tank" so that the flow volume of each cylinder differs between the cylinders. Structure It is a common problem in general.

In addition, Japanese Unexamined Patent Application Publication No. 3-29572 discloses a technique of connecting an EGR pipe to each port " port " However, this technique has a new problem in that the distance from the EGR valve to the EGR introduction hole becomes long, and a time delay occurs in the change of the EGR rate by that amount, or the EGR loss becomes large. In addition, there is a problem that the production cost rises because of a complicated structure. Therefore, it is aimed at making it possible to smoothly change the EGR rate in the cylinder for every stroke, without generating the above-mentioned new subject.

An object of the present invention is to provide an intake system structure of an internal combustion engine with an EGR device, which makes it possible to smoothly change the EGR rate in a cylinder for each stroke.

1 is a schematic diagram showing an intake system structure of an internal combustion engine with an EGR device according to an embodiment of the present invention.

2 is a cross-sectional view showing the configuration of a junction portion between an EGR pipe and an intake pipe according to an embodiment of the present invention.

Fig. 3 is a diagram showing a change in the EGR rate distribution in the intake air for each stroke at the time of acceleration, and shows a change for each stroke in the order of (a) to (h).

Fig. 4 is a diagram showing a change in each stroke of the fuel injection amount corresponding to a change in each stroke of the EGR rate in the cylinder.

5 is a schematic diagram showing an intake system structure of a conventional internal combustion engine with an EGR device.

FIG. 6 is a diagram showing a change in the EGR rate distribution in the intake air for each stroke at the time of the conventional acceleration, and a diagram showing the change for each stroke in the order of (a) to (h). FIG.

Fig. 7 is a diagram showing a change in each stroke of a fuel injection amount corresponding to a change in each stroke of an EGR rate in a conventional cylinder.

For this reason, in the intake system structure of the internal combustion engine with EGR apparatus of this invention, the introduction hole of the exhaust gas from an exhaust path is formed in the upstream of the branch part which the intake path branches for every cylinder, A flow path leading to the intake hole is formed independently for each cylinder, the flow path length of the flow path is made into an unequal length in at least two cylinders, and the flow path volume is made equal or approximately equal in volume between the cylinders. To form.

As a result, the time until the air (mixer with the intake exhaust) near the inlet hole is sucked into each cylinder is approximately the same between the cylinders, and in the mixer in each cylinder when the valve of the EGR device is closed. The rate of exhaust (EGR rate) changes smoothly every stroke.

Also preferably, a plurality of the introduction holes are formed around the intake passage. As a result, the exhaust gas and the intake air are surely mixed without any non-uniformity.

Further, the smaller the flow volume of the passage from the introduction hole to the intake hole of each cylinder, the more preferable. As a result, the time delay until the air near the inlet hole is sucked into each cylinder is reduced, and the EGR rate in each cylinder also changes rapidly with respect to the closing operation of the valve of the EGR device.

Embodiment of the Invention

EMBODIMENT OF THE INVENTION Hereinafter, the Example of this invention is described with reference to drawings.

Example

1 to 4 show the intake system structure of an internal combustion engine with an EGR device according to one embodiment of the present invention. First, the structure of the intake system structure of the internal combustion engine which concerns on a present Example based on FIG. 1, FIG. 2 is demonstrated. In addition, the internal combustion engine which concerns on a present Example shall be comprised as a diesel engine "diesel engine" of a four-cylinder series diesel engine.

As shown in FIG. 1, four cylinders 3A-3D are arranged in series in the engine "engine" (internal combustion engine) 1. The engine "engine" 1 according to the present embodiment is configured as a diesel engine "diesel engine" of a four-cylinder series engine, and the fuel in the cylinders 3A to 3D is provided at the top of each cylinder 3A to 3D. An injector " injector " not shown for directly injecting is provided.

Intake holes 4A to 4D are formed near the tops of the cylinders 3A to 3D, and cylinder cylinders "cylinder head" 2 of the engine "engine" 1 communicate with the intake holes 4A to 4D. Intake ports " ports " (5A to 5D) are provided. In addition, near the top of each of the cylinders 3A to 3D, exhaust holes are formed along with the intake holes 4A to 4D, and the cylinder head " cylinder head " 2 also drills an exhaust port " port " Although installed, the illustration is omitted.

An intake manifold "manifold" 10 is connected to the intake port "port" (5A to 5D). The intake exhaust fold " manifold " 10 is branched from the collecting pipe 11 to which one end is connected to the intake pipe 6 on the upstream side and from the other end (branch) 13 of the collecting pipe 11 to each intake port. It consists of the branch pipes 12A-12D connected to "port" (5A-5D). Each branch pipe 12A-12D is formed so that the length may not be the same but internal volume may be the same. In addition, the intake pipe 6 communicates with an air cleaner " air cleaner " shown in the upstream side, and a throttle " throttle " valve 7 for adjusting the air flow rate is disposed therein. Then, the intake pipe 6, the intake manifold " manifold " 10, and the intake ports " port " 5A to 5D allow air to be introduced into the respective cylinders 3A to 3D. Is formed.

The engine " engine " 1 is provided with an EGR device 20 for recycling the exhaust gas from the exhaust passage not shown in the drawing to the intake passage 9 above. The EGR device 20 is composed of an EGR pipe 24 for communicating the exhaust passage and the intake passage 30, and an EGR valve 21 disposed in the EGR tube 24 to control the amount of recycle of the exhaust gas. The EGR pipe 24 is joined to the downstream side of the excretion portion of the throttle "throttle" valve 7 of the intake pipe 6. As shown in FIG. 2, the EGR tube 24 is formed in the annular shape so that the edge part may enclose the intake pipe 6. As shown in FIG. At the junction between the intake pipe 6 and the EGR pipe 24, a plurality of EGR introduction holes 23 communicating with the inside of the intake pipe 6 and the inside of the EGR pipe 24 are formed.

By the above configuration, air (intake) sucked into the intake pipe 6 via the air cleaner "air cleaner" (not shown) is introduced from the EGR introduction hole 23 at the junction with the EGR pipe 24. It is mixed with the exhaust to become a mixer. At this time, since a plurality of EGR introducing holes 23 are formed around the intake pipe 6, the exhaust gas and the intake air are reliably mixed without being uneven. And the mixer which flowed into the collection pipe 11 of the intake manifold "manifold" from the intake pipe 6 branches from the branch part 13 to each branch pipe 12A-12D, and intake port "port" (5A- Inhalation in each of the cylinders 3A to 3D is carried out via 5D, at which time the mixer passes through the flow passage 8A to the first cylinder 3A and the flow passage 8B to the second cylinder 3A. Via the flow path 8C to the third cylinder 3C and through the flow path 8D to the fourth cylinder 3D, but these flow paths 8A to 8D are each branch pipe. Since the internal volumes of 12A-12D are the same, they are equal.

Next, the operation of the intake system structure of the internal combustion engine with the EGR device as one embodiment of the present invention configured as described above will be described with reference to FIGS. 3 and 4.

3 (a) to 3 (h) show an example of the change in the EGR rate in the intake passage 9 and the respective cylinders 3A to 3D when the EGR valve 21 is operated. This is typical of the administration to the eighth administration. The order of intake of each of the cylinders 3A to 3D is set in the order of 1-3-4-2 cylinders, and as shown in Fig. 3A, first, the air intakes to the first cylinder 3A in the first stroke. I do it.

3 (a) to 3 (h), the black portion represents the exhaust, that is, the EGR rate 100%, while the white portion, on the contrary, represents the intake air, that is, the EGR rate%. In addition, the dark gray portion represents a mixer having an EGR rate of 50%, and the light gray portion represents a mixer having an EGR rate of 25%. Here, as shown in Fig. 3 (a), the EGR valve 21 is operated so that the flow rate ratio of the exhaust gas to the total flow rate in the first stroke is 50% (Fig. 3 (a)). The EGR valve 21 is operated so that the flow rate ratio of the exhaust is 25% [Fig. 3 (b)], and the EGR valve 21 is completely closed after the third stroke (Figs. 3 (c) to 3 (h). )].

By the closing operation of the EGR valve 21 as described above, the EGR rate of the mixer in the intake passage 9 gradually decreases for each stroke as shown in Figs. 3A to 3H. Since the flow path volumes from the inlet hole 21 to the respective cylinders 3A to 3D are substantially the same, the EGR rate of the mixer sucked into each of the cylinders 3A to 3D does not vary from stroke to stroke as in the prior art. As shown in Fig. 4, the temperature gradually decreases with each stroke.

For this reason, in order to prevent the generation of graphite, when the optimum amount of fuel determined by the EGR rate in the cylinder and the engine "engine" rotational speed is injected, the fuel injection amount gradually increases from stroke to stroke as shown in FIG. I will go. Therefore, by performing annealing control such as a filter " filter " process, a smooth fuel change amount can be obtained, whereby smooth acceleration can be obtained.

In addition, the broken line in FIG. 4 shows the EGR rate change regarding the conventional intake system structure, and the fuel injection amount change for every stroke when fuel is increased smoothly without generating graphite according to this conventional EGR rate change. However, as can be seen in contrast to the conventional fuel injection amount change, it is possible to increase the fuel injection amount more quickly, and to improve the response "response" to the acceleration demand of the driver "driver". do.

In addition, the change of the EGR rate in the intake path 9 and each cylinder 3A-3D shown to FIG. 3, FIG. 4 is an example to the last, and the intake path 9 content and the content of each cylinder 3A-3D are the same. When the relationship is changed or when the change in the opening degree of the EGR valve 21 is changed, the change state for each stroke of the EGR rate also differs from the change state shown in FIG. However, as long as the flow volume from the EGR introducing hole 23 to each of the cylinders 3A to 3D is the same or substantially the same, a smooth change in the EGR rate without variation can be ensured.

As described above, according to the structure of the intake air, the intake air flows from the EGR introducing hole 23 to the intake holes 4A to 4D of the respective cylinders 3A to 3D so that the intake volume is approximately equal between the cylinders 3A to 3D. Since the furnace 9 is formed, there is an advantage that the EGR rate of the mixer sucked into each of the cylinders 3A to 3D can be smoothly changed for each stroke in accordance with the operation of the EGR valve 21 during acceleration or deceleration. . Thereby, there is also an advantage that smooth acceleration can be obtained even when the optimum fuel amount determined by the EGR rate in the cylinder and the engine " engine " rotational speed is injected to control the generation of graphite.

In addition, since a plurality of EGR introducing holes 23 are formed around the intake pipe 6, it is possible to reliably mix exhaust and intake air without unevenness. Therefore, the intake air of each cylinder 3A to 3D is discharged from the EGR inlet hole 23. There is also an advantage that the volume of the flow path leading to the holes 4A to 4D can be reduced, and the response delay of the change in the EGR rate with respect to the operation of the EGR valve 21 can be reduced.

Moreover, according to this intake system structure, since the EGR pipe 22 does not need to be connected to each intake port "port" (5A to 5D), the device structure can be simplified, and EGR is introduced from the EGR valve 21. There is also an advantage that the distance to the hole 23 is not long.

As mentioned above, although one Embodiment of the intake system structure of the internal combustion engine with EGR apparatus of this invention was described, this invention is not limited to the said Example, It variously deforms and implements in the range which does not deviate from the meaning of this invention. can do. For example, although each branch pipe 12A-12D of the intake manifold "manifold" 10 which concerns on a present Example is equal in length, it may be formed in equal length. In this case, the cross-sectional area of each branch pipe 12A-12D can be made the same.

In this embodiment, the internal volume of the branch pipes 12A to 12D of the intake manifold " manifold " 10 is equally assuming that the internal volumes of the intake ports " ports " 5A to 5D are the same. As a result, the flow volume of the intake holes 4A to 4D of the cylinders 3A to 3D is made the same. However, when there is a nonuniformity in the internal volume of each intake port "port" (5A to 5D), this nonuniformity The internal volume of the branch pipes 12A to 12D may be set so as to eliminate the problem.

The intake manifold "manifold" 10 has a structure which branches directly from the collecting pipe 11 to the branch pipes 12A to 12D, but surges between the collecting pipe 11 and the branch pipes 12A to 12D. You can also install a "surge tank". In this case, however, in consideration of the flow volume in the surge tank " surge tank ", the respective flow paths from the EGR introduction hole 23 to the intake holes 4A to 4D of the respective cylinders 3A to 3D are the same. The internal volume of the engine 12A-12D is set.

Moreover, the structure which integrated the intake manifold "manifold" 10 into the intake port "port" (5A-5D) may be sufficient.

In this embodiment, the EGR pipe 24 is joined to the intake pipe 6, but the inside of the collection pipe 11 and the EGR pipe 24 are joined to the collection pipe 11 of the intake manifold “manifold” 10. The plurality of EGR introduction holes 23 may be formed so as to communicate with each other. Thereby, the flow volume of the flow path from the EGR introduction hole 23 to the intake holes 4A to 4D of each of the cylinders 3A to 3D is made smaller, so that the air near the EGR introducing hole 23 is reduced to each cylinder (3A to 3D). The time delay before inhalation can be reduced.

Moreover, of course, this invention is applicable not only to a diesel engine "diesel engine" but also to a gasoline engine "gasoline engine".

As described in detail above, according to the intake system structure of the internal combustion engine with the EGR apparatus of the present invention, the intake path is formed so that the flow volume of the flow path from the introduction hole to the intake hole of each cylinder is equal or approximately equal between the cylinders. Therefore, there is an advantage that the EGR rate of the mixers sucked in each cylinder can be smoothly changed for each stroke in accordance with the operation of the valve of the EGR device during acceleration or deceleration (claim 1).

In addition, when a plurality of inlet holes are provided around the intake pipe, there is an advantage that it is possible to reliably mix the exhaust and the intake air unevenly (claim 2).

Claims (2)

In the intake system structure of an internal combustion engine with an EGR device 20 for recycling a part of the exhaust gas from the exhaust passage to the intake passage, The introduction hole 23 of the exhaust gas from the exhaust passage is formed upstream 6 of the branch portion 13 where the intake passage 9 branches into each cylinder, Flow paths 12A to 12D extending from the introduction hole 23 to the intake holes 4A to 4D of the respective cylinders 3A to 3D are formed independently for each cylinder, and the flow path length from the branch portion is at least two. Of the internal combustion engine with an EGR apparatus, characterized in that the intake passage 9 is formed so as to have an uneven length in the two cylinders, and that the flow path volume becomes the same volume or approximately the same volume in all the cylinders 3A to 3D. Intake machine structure. The method of claim 1, The intake system structure of an internal combustion engine with an EGR device, characterized in that a plurality of the introduction holes (23) are formed around the intake passages (6, 9).