JP2011080396A - Egr device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To uniform the amount of EGR in each cylinder by eliminating a variation in the passage cross-sectional area of each minimum EGR passage even if an EGR distribution/supply means is provided by joining a plurality of members. <P>SOLUTION: Resin first to third members 6-8 are joined by vibration welding, thereby integrally providing an intake manifold 1 and the EGR distribution/supply means 3. The EGR distribution/supply means 3 includes a plurality of independent branch passages 5 distributing/supplying EGR gas to each branch portion 2 and communicating with each branch portion 2. The minimum EGR passage 9 for uniforming the amount of EGR with respect each cylinder is provided in the middle of each branch passage 5, and is formed by a molding die die-cut in one direction. As a result, even if the first to third members 6-8 are vibration-welded, the passage cross-sectional area of each minimum EGR passage 9 is set to a design value without change, emissions are reduced, an engine is stabilized, and fuel economy is improved. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an EGR device that returns a part of exhaust gas of an engine (an internal combustion engine that generates power by combustion of fuel) to an intake passage as EGR gas, and in particular, EGR gas that individually distributes EGR gas to a plurality of cylinders in the engine. It relates to distribution supply means.

(Conventional technology)
An EGR device is known as a technique for suppressing generation of NOx (nitrogen oxide) in engine exhaust gas.
The EGR device includes an EGR flow path that returns a part of the exhaust gas flowing through the exhaust passage to the intake passage as EGR gas, and mixes an EGR gas that is a non-combustible gas into a part of the intake air, so that the combustion temperature of the engine combustion chamber This is a technology for suppressing NOx generation and effectively suppressing the generation of NOx.

  An EGR device that individually distributes EGR gas for each of a plurality of cylinders in an engine is known. This EGR device distributes and supplies EGR gas to each of a plurality of cylinder-by-cylinder intake passages (branch portions in the case of intake manifolds) that guides intake air independently for each cylinder of the engine. EGR distribution supply means is used as means for distributing the EGR gas to be distributed to the intake passages for each cylinder (see, for example, Patent Document 1).

With reference to FIG. 3, the EGR distribution supply means disclosed in Patent Document 1 will be described. In addition, a code | symbol shows the same functional thing as the [form for inventing] and [Example] which are mentioned later.
In the technique of Patent Document 1, a plurality of branch portions 2 (an example of an intake passage for each cylinder) that guides intake air to each cylinder by joining a first member J1 made of resin and a second member J2 made of resin. An intake manifold 1 formed inside is provided, and EGR distribution supply means 3 for distributing and supplying EGR gas to each branch portion 2 is provided.

  The EGR distribution supply means 3 disclosed in Patent Document 1 includes a gas distribution passage 4 that distributes and supplies EGR gas supplied from the EGR introduction port 10 to the vicinity of each branch section 2, and the gas distribution path 4 and each branch section. 2 and the gas distribution passage 4 and the branch passage 5 are provided by an internal space formed between the first member J1 and the second member J2.

(Problems of conventional technology)
The first member J1 and the second member J2 are joined by a vibration welding technique. That is, the first member J1 and the second member J2 are bonded together by melting each other. For this reason, a welding allowance (sinking amount due to welding) is generated by vibration welding at a joint portion between the first member J1 and the second member J2.
It is difficult to make the welding allowance uniform in all the joints, the pressurization state of the first member J1 and the second member J2 at the time of welding, the warp generated in the first member J1 and the second member J2, etc. As a result, variations occur in the welding allowance at the joint between the first member J1 and the second member J2.

Here, the branch passages 5 respectively communicating with the respective branch portions 2 are provided with a minimum EGR passage 9 for equalizing the amount of EGR supplied to each branch portion 2 (passage breakage in the EGR flow path in the EGR distribution supply means 3). A passage having the smallest area) is provided.
However, since the branch passage 5 including the minimum EGR passage 9 is provided by the space between the first member J1 and the second member J2 as described above, each minimum EGR passage is caused by a variation in welding allowance. 9 has a variation in the cross-sectional area of the passage 9, and the amount of EGR supplied to each cylinder varies.

JP 2003-239816 A

  The present invention has been made in view of the above-mentioned problems, and the object of the present invention is to reduce the variation in the cross-sectional area of each minimum EGR passage even if the EGR distribution supply means is provided by joining a plurality of members. The present invention provides an EGR device that can eliminate the occurrence and make the amount of EGR supplied to each cylinder uniform.

[Means of Claim 1]
The EGR apparatus according to claim 1 employs the following technical means to achieve the above object.
The EGR device includes a gas distribution passage that guides EGR gas in the vicinity of a plurality of cylinder-specific intake passages that guide intake air independently for each of a plurality of cylinders in the engine, and the gas distribution passage and the plurality of cylinder-specific intake passages are independent of each other. EGR distribution supply means having a plurality of branch passages communicating with each other.
The EGR distribution supply means is provided by joining a plurality of members.
In the EGR flow path in the EGR distribution and supply means, the minimum EGR passage having the smallest passage cross-sectional area is provided in each branch passage.
Each minimum EGR passage is formed by a molding die cut in one direction, and each minimum EGR passage is provided through one member.

  Thus, since the minimum EGR passage is provided through one member, there is a problem that even if a plurality of members are joined to provide the EGR distribution supply means, the passage cross-sectional area of each minimum EGR passage changes due to the joining. Absent. As a result, the cross-sectional area of each minimum EGR passage can be reliably set to the design value, and variations in the amount of EGR supplied to each cylinder can be suppressed.

[Means of claim 2]
The EGR device according to the means of claim 2 is provided with EGR distribution supply means together with the intake manifold by joining a plurality of members.
For this reason, it is not necessary to separately provide an EGR distribution supply means, and the cost required for the EGR distribution supply means can be suppressed.

[Means of claim 3]
The gas distribution passage of the EGR device according to claim 3 is a branch passage that branches from the EGR introduction port to each branch passage, and the passage distance from the EGR introduction port to each branch passage is made uniform by this branch passage. At the same time, the passage distance from the EGR inlet to each branch passage is extended. Thus, by equalizing the passage distance from the EGR introduction port to each branch passage, the passage resistance from the EGR introduction port to each branch passage can be made uniform and supplied to each cylinder due to variation in passage resistance. It is possible to avoid a problem that the EGR amount varies.

Further, by extending the passage distance from the EGR introduction port to each branch passage, heat release of the EGR gas passing through the gas distribution passage (branch passage) is promoted, and the EGR gas supplied to the intake passage for each cylinder. The temperature can be lowered. As a result, the temperature rise of the intake air sucked into each cylinder can be suppressed, and the intake charging efficiency can be increased.
In order to improve the heat dissipation (cooling performance) of the EGR gas in the gas distribution passage, the EGR distribution supply means is provided so that it is exposed to the outside air (vehicle running wind, etc.), or the EGR distribution supply means is provided with heat dissipation. It is desirable to provide unevenness (such as a heat radiating fin) to promote.

(Example 1) which is sectional drawing of the intake manifold in which an EGR distribution supply means is provided. (Example 1) which is a top view of the 2nd member in which a branch passage is provided. It is a disassembled perspective view of an intake manifold (conventional example).

[Mode for Carrying Out the Invention] will be described with reference to FIGS. 1 and 2.
The EGR device includes EGR distribution supply means 3 that distributes and supplies EGR gas to each branch portion 2 of the intake manifold 1 (an example of an intake passage for each cylinder).
The EGR distribution supply means 3 is provided for each branch unit 2 and distributes the EGR gas introduced from the EGR introduction port 10 to the vicinity of each branch unit 2, and the gas distribution channel 4. And a branch passage 5 for guiding the EGR gas guided to the vicinity of the branch part 2 to the branch part 2.

The intake manifold 1 and the EGR distribution supply means 3 are provided by vibrating and welding first to third members 6 to 8 (an example of a plurality of members) made of resin.
A minimum EGR passage 9 having a minimum passage cross-sectional area in the EGR flow path in the EGR distribution supply means 3 is provided in each branch passage 5.
Each branch passage 5 including the minimum EGR passage 9 is provided in the second member 7 (one of a plurality of members). Each branch passage 5 (including the minimum EGR passage 9) of the second member 7 is formed by a molding die that is die-cut in one direction, and the minimum EGR passage 9 is provided through the second member 7. It is done.

  Even if a variation in welding margin occurs at the joint portion of the first to third members 6 to 8 by vibration welding the first to third members 6 to 8, each minimum EGR passage 9 attaches the second member 7 to each other. Since it is provided penetrating, there is no problem that the passage cross-sectional area of each minimum EGR passage 9 changes due to variations in welding allowance. As a result, the cross-sectional area of each minimum EGR passage 9 can be reliably set to the design value, and variations in the amount of EGR supplied to each cylinder can be suppressed.

The EGR apparatus according to the first embodiment will be described with reference to FIGS. 1 and 2. In the following embodiments, the same reference numerals as those in the above-mentioned [Mode for Carrying Out the Invention] denote the same functional objects.
[Outline of EGR device]
Before describing the characteristic technology of the first embodiment, a schematic configuration of the EGR apparatus will be described.
An engine is an internal combustion engine for driving a vehicle (gasoline engine, diesel engine, etc.) that generates rotational output by combustion of fuel, an intake passage that guides intake air into each cylinder, and exhaust gas generated in each cylinder to the atmosphere. And an exhaust passage for discharging inside.

The intake passage is constituted by internal passages of the intake pipe, the intake manifold 1 and the intake port.
The intake pipe is a passage member that forms an intake passage from the outside air intake to the intake manifold 1. The intake pipe is an air cleaner that removes dust and dirt contained in the intake air sucked into the engine, and is sucked into the cylinder. A throttle valve or the like is provided for adjusting the intake flow rate.
The intake manifold 1 is an intake pipe that distributes the intake air supplied from the intake pipe to each cylinder of the engine, and a specific structure thereof will be described later.
The intake port is formed for each cylinder in the cylinder head of the engine and guides the intake air distributed by the intake manifold 1 into the cylinder.

The exhaust passage is constituted by internal passages of an exhaust port, an exhaust manifold, and an exhaust pipe.
Similar to the intake port, the exhaust port is formed for each cylinder in the cylinder head of the engine, and guides exhaust gas generated in the cylinder to the exhaust manifold.
The exhaust manifold is a collecting pipe for exhaust gas discharged from each exhaust port. The exhaust pipe is a passage member that discharges exhaust gas toward the atmosphere. The exhaust pipe is provided with a catalyst for purifying exhaust or a DPF for collecting particulates contained in the exhaust gas. .

In the cylinder head in which the intake port and the exhaust port are formed as described above, an intake valve that opens and closes an outlet end of the intake port (a boundary portion between the intake port and the cylinder) and an inlet end of the exhaust port (for each cylinder) An exhaust valve that opens and closes a boundary portion between the cylinder and the exhaust port is provided.
Each cylinder of the engine repeats the steps of suction, compression, explosion, and exhaust sequentially. Then, the intake valve is opened at the start of intake (when the cylinder internal volume increases as the piston descends), and the intake valve closes at the end of intake (when the cylinder internal volume increases after the piston descends). It is done. As a result of the intake operation of the engine, an intake air flow flows from the outside air intake into the cylinder of the engine in the intake passage.
Similarly, the exhaust valve is opened at the start of exhaust (when the cylinder internal volume decreases as the piston moves up), and the exhaust valve is opened at the end of exhaust (when the cylinder internal volume decreases after the piston increases). Closed. As a result of the exhaust operation of the engine, an exhaust gas flow is generated in the exhaust passage from the cylinder of the engine toward the atmospheric discharge portion (exhaust outlet).

An engine intake / exhaust system is provided with at least a high-pressure EGR device (a device generally called an EGR device conventionally).
The high-pressure EGR device has a high exhaust pressure range (a range where high exhaust pressure is generated on the exhaust side upstream of the catalyst or the DPF) and a high intake negative pressure generation range (on the intake downstream side of the throttle valve). This is an exhaust gas recirculation device that is good at returning a large amount of EGR gas to the engine by connecting it to the inside of the intake passage in a range where intake negative pressure is generated). A high-pressure EGR flow path returning to the intake downstream side of the passage is provided.

A specific example of the high pressure EGR apparatus will be described.
In the middle of the high pressure EGR flow path, a high pressure EGR adjustment valve that adjusts the flow rate of the EGR gas by adjusting the opening of the high pressure EGR flow path, a high pressure EGR cooler that cools the EGR gas returned to the intake side, A high pressure cooler bypass that bypasses the EGR gas returned to the intake side from the high pressure EGR cooler, and a high pressure EGR cooler switching valve that switches between the high pressure EGR cooler and the high pressure cooler bypass are provided.

The high-pressure EGR cooler is a water-cooled gas cooler that cools high-temperature EGR gas by exchanging heat between engine cooling water that circulates and cools the engine and high-temperature EGR gas, and heat exchange between engine cooling water and EGR gas. The heat exchanger which performs is provided.
Although it is desirable that the high-pressure EGR adjustment valve, the high-pressure EGR cooler, the high-pressure cooler bypass, and the high-pressure EGR cooler switching valve are integrally provided in advance as a high-pressure EGR module, it is not limited thereto.

Each electrical component (high pressure EGR adjustment valve and high pressure EGR cooler switching valve) mounted on the high pressure EGR device is controlled by an ECU (abbreviation of engine control unit).
The ECU includes a microcomputer having a well-known structure that includes functions of a CPU that performs control processing and arithmetic processing, a storage device (memory such as ROM and RAM) that stores various programs and data, an input circuit, and an output circuit. This is an electronic control device for engine control.

This ECU performs engine operation control (fuel injection control, etc.) based on a control program stored in a storage device and various sensor signals (occupant operation signals, various detection sensor signals, etc.). The EGR control program for controlling the operation of the high-pressure EGR device is installed in the storage device of the ECU.
This EGR control program corresponds to a “cooler switching program” for switching the high-pressure EGR cooler switching valve based on the warm-up state of the engine (for example, the temperature of engine cooling water), the engine speed and the engine load (engine torque). And an “EGR flow rate control program” for controlling the opening degree of the high pressure EGR regulating valve.

[Characteristics of Example 1]
The EGR apparatus according to the first embodiment includes EGR distribution supply means 3 that returns EGR gas to each branch portion 2 of the intake manifold 1.
First, the configuration of the intake manifold 1 will be described.
1 and 2 show an intake manifold 1 attached to an inline 4-cylinder engine. The intake manifold 1 is an intake distribution pipe that distributes intake air supplied from an intake pipe to each cylinder of the engine, and a surge tank for preventing intake pulsation and intake interference that adversely affects the accuracy of the flow sensor. 11 and four branch portions 2 communicating with the respective intake ports are provided on the intake downstream side of the surge tank 11.

A flange portion that is fastened by an intake pipe and bolts (not shown) is provided at an intake upstream end (intake introduction portion) of the surge tank 11 in the intake manifold 1. Further, a flange portion that is fastened by a cylinder head of an engine and bolts (not shown) is provided at the intake downstream end (each intake port connection portion) of each branch portion 2 in the intake manifold 1.
The four branch portions 2 extending from the surge tank 11 to the connection portion of each intake port are arranged along the cylinder row of the engine, and each of them is provided in a substantially C-shaped manner in a similar manner.

The intake manifold 1 is provided by joining a plurality of (three) members including a first member 6, a second member 7, and a third member 8.
The first member 6 is a member fastened to the engine, and each branch portion 2 forms a connection portion with each intake port.
The 2nd member 7 is a member joined to the 1st member 6, and forms the half (one side) of each branch part 2 curved in the substantially C shape.
The 3rd member 8 is a member joined to the 2nd member 7, and forms the half (other side) of each branch part 2 curved in the substantially C shape.

The first to third members 6 to 8 are all made of a thermoplastic synthetic resin, and are, for example, injection-molded into a predetermined shape with a nylon resin blended with glass fibers.
A welding seal portion 12 that is welded by a vibration welding technique is provided at a joint portion between the first member 6 and the second member 7 and a joint portion between the second member 7 and the third member 8.
And by welding each welding seal part 12 by a vibration welding technique, the 1st-3rd members 6-8 are joined and the intake manifold 1 is formed.

The intake manifold 1 is integrally provided with EGR distribution supply means 3 that guides EGR gas to each branch portion 2.
The EGR distribution supply means 3 includes a gas distribution passage 4 that guides EGR gas in the vicinity of each branch portion 2 provided in the intake manifold 1, and the end of the gas distribution passage 4 and each branch portion 2 are independently connected to each other. Four branch passages 5 are provided for communication.

  The EGR distribution supply means 3 is provided integrally with the intake manifold 1 as described above, and by joining the first to third members 6 to 8 constituting the intake manifold 1 together with the intake manifold 1, EGR A distribution supply means 3 is provided.

The gas distribution passage 4 is provided at the downstream end portion of the EGR gas in the high-pressure EGR flow path, and distributes and supplies the EGR gas to each branch passage 5.
The gas distribution passage 4 is formed by the internal space of the second member 7 and the third member 8. As shown in FIG. 2, the gas distribution passage 4 is provided by a branch passage that branches from the EGR inlet 10 for introducing EGR gas into the gas distribution passage 4 toward the branch passages 5. This branch passage is provided so that the passage distance from the EGR introduction port 10 to each branch passage 5 is made uniform and the passage distance from the EGR introduction port 10 to each branch passage 5 is extended.

Specifically, as a means for extending the passage distance from the EGR introduction port 10 to each branch passage 5, the gas distribution passage 4 of the first embodiment has a three-layer passage structure in the vertical direction as shown in FIG. Are provided so as to ensure a large contact area between the EGR gas and the wall surface forming the gas distribution passage 4.
Further, an EGR introduction port 10 is provided at the end of the passage of the first layer (the upper layer in the figure) so that the flow path length from the EGR introduction port 10 to the branching portion (center portion) 4a of the first layer is gained. Is provided.
Similarly, a branch passage 5 is provided at a passage end of the third layer (lower layer in the drawing), and is provided so as to gain a flow path length from the branch portion 4b of the second layer to the branch passage 5.

Each branch passage 5 is formed by the internal space of the first to third members 6 to 8. Each branch passage 5 is an independent passage that connects each end portion of the branch passage in the gas distribution passage 4 and each branch portion 2, and an intermediate portion of each branch passage 5 is provided in the EGR distribution supply means 3. In the EGR flow path, a minimum EGR passage 9 is provided in which the passage cross-sectional area is minimum.
The minimum EGR passage 9 functions as an adjusting means for aligning the amount of EGR supplied to each branch portion 2. If the cross-sectional area of the minimum EGR passage 9 is different from the design value, each branch portion 2 has Supply unevenness occurs in the supplied EGR amount.

In the first embodiment, as a technique for providing the cross-sectional area of each minimum EGR passage 9 at a design value, each minimum EGR passage 9 is formed by a molding die that is die-cut in one direction.
Specifically, each minimum EGR passage 9 in this embodiment is formed at the downstream end portion of the EGR gas in the branch passage 5 provided in the second member 7, and the second member 7 is made of resin. At the time of injection molding, the branch passage 5 including each minimum EGR passage 9 is formed by being die-cut in one direction by a molding die for molding the second member 7.
Thereby, each minimum EGR passage 9 is provided in a structure penetrating the second member 7.

[Effect of Example 1]
Each minimum EGR passage 9 of the first embodiment is provided by being punched in one direction, and is provided through the second member 7. Therefore, even if the first to third members 6 to 8 are vibration welded and a variation in welding margin occurs in the joint portion (welding seal portion 12) of the first to third members 6 to 8, each minimum EGR Since the passage 9 is provided through the second member 7, there is no problem that the passage cross-sectional area of each minimum EGR passage 9 changes due to variation in welding allowance.
As a result, the cross-sectional area of each minimum EGR passage 9 can be reliably set at the design value, and variations in the amount of EGR supplied to each cylinder can be suppressed.

As described above, the passage cross-sectional area of each minimum EGR passage 9 is surely provided at the design value, so that the EGR amount control with high accuracy is possible, and the variation in the EGR gas between the cylinders is suppressed, thereby reducing the emission. In addition, the engine can be stabilized.
In addition, since the EGR amount control with high accuracy becomes possible, it becomes possible to give the engine an EGR amount that is close to the engine operating limit, and it is possible to suppress the emission to the limit or improve the fuel consumption. .

  In the first embodiment, the EGR distribution supply means 3 is provided together with the intake manifold 1 by joining the first to third members 6 to 8. For this reason, it is not necessary to provide the EGR distribution supply means 3 separately, and the cost of the EGR distribution supply means 3 can be suppressed.

The gas distribution passage 4 of the first embodiment is provided in the branch passage so that the passage distance from the EGR introduction port 10 to each branch passage 5 is made uniform, and the passage distance from the EGR introduction port 10 to each branch passage 5 is extended. ing.
Thus, by equalizing the passage distance from the EGR introduction port 10 to each branch passage 5, the passage resistance from the EGR introduction port 10 to each branch passage 5 can be made uniform. It is possible to avoid the problem that the amount of EGR supplied to the apparatus varies.

Further, the passage distance from the EGR introduction port 10 to each branch passage 5 is extended, so that the heat release of the EGR gas passing through the gas distribution passage 4 (branch passage) is promoted. As a result, the temperature of the EGR gas supplied to each branch section 2 can be lowered, and the temperature rise of the intake air sucked into each cylinder can be suppressed to increase the intake charging efficiency in the engine.
In addition, in order to improve the heat dissipation (cooling performance) of the EGR gas in the gas distribution passage 4, the EGR distribution supply means 3 is provided so that outside air (vehicle driving wind or the like) hits it and is supplied to each branch unit 2. The temperature of the EGR gas may be further lowered. Alternatively, the outer surface of the EGR distribution supply unit 3 may be provided with unevenness (radiation fins or the like) that promotes heat dissipation so that the temperature of the EGR gas supplied to each branch portion 2 is further lowered.

In the above-described embodiment, an example in which three members (first to third members 6 to 8) are joined has been described. However, the EGR distribution supply unit 3 may be provided by joining two members. That is, the number of members provided with the EGR distribution supply means 3 may be any number as long as it is two or more.
In the above embodiment, the example in which the EGR distribution supply means 3 is provided by the members (first to third members 6 to 8) constituting the intake manifold 1 is shown. However, the EGR distribution supply means 3 is different from the intake manifold 1. It may be provided on the body.

1 Intake manifold 2 Branch section (intake passage for each cylinder)
3 EGR distribution supply means 4 Gas distribution passage (branch passage)
5 branch passage 6 first member (one of a plurality of members)
7 Second member (one of a plurality of members)
8 Third member (one of multiple members)
9 Minimum EGR passage 10 EGR inlet

Claims (3)

A gas distribution passage (4) for guiding EGR gas in the vicinity of a plurality of cylinder-by-cylinder intake passages (2) for independently leading intake air to a plurality of cylinders in the engine;
A plurality of branch passages (5) for independently communicating the gas distribution passage (4) and the plurality of cylinder-specific intake passages (2);
In an EGR device comprising EGR distribution supply means (3) having
The EGR distribution supply means (3) is provided by joining a plurality of members (6-8),
In the EGR flow path in the EGR distribution supply means (3), the minimum EGR passage (9) having the smallest passage cross-sectional area is provided in each branch passage (5),
Each minimum EGR passage (9) is formed by a molding die cut in one direction, and each minimum EGR passage (9) is provided through one member (7). . The EGR device according to claim 1,
The plurality of members (6 to 8) are joined to form an intake manifold (1) that distributes and supplies intake air to each cylinder of the engine,
The plurality of cylinder-specific intake passages (2) are a plurality of branch portions provided in the intake manifold (1),
The EGR apparatus, wherein the EGR distribution supply means (3) and the intake manifold (1) are provided by joining the plurality of members (6 to 8). The EGR device according to claim 1 or 2,
The gas distribution passage (4) is a branch passage branched from the EGR introduction port (10) for introducing EGR gas into the gas distribution passage (4) toward the branch passages (5). It is characterized by equalizing the passage distance from the EGR introduction port (10) to each branch passage (5) by the branch passage and extending the passage distance from the EGR introduction port (10) to each branch passage (5). EGR device to do.

Images