JP2022143035A - engine intake manifold - Google Patents

Abstract

The present invention provides an intake manifold excellent in the function of treating moisture contained in EGR gas.
An intake branch passage (18) of an intake manifold (5) has an upward portion (24), a vertex portion (25) and a downward inclined portion (26). It is composed of a portion 26 a and a single passage portion 26 b on the upstream side of the partition wall 27 . The EGR gas outlet 33 opens toward a portion of the single passage portion 26b that is closer to the vertex portion 25 than the partition wall 27 is. Even if condensed water is generated in the EGR distribution passage 32, the condensed water does not accumulate in the surge tank 14, but is atomized by the intake air and scattered downstream, so that no problem occurs. Since the EGR gas outlet 33 is offset so as to approach the vertex 25, the EGR gas and the intake air can be dispersed more evenly, and the EGR gas concentrations at the two intake ports 28 can be equalized.
[Selection drawing] Fig. 4

Description

The present invention relates to an intake manifold having an EGR distribution passage.

2. Description of the Related Art In an engine for an automobile or the like, part of the exhaust gas is recirculated as EGR gas to the intake system in order to improve fuel efficiency and purification performance of the exhaust gas. A simple recirculation mode of EGR gas is to jet it into the surge tank of the intake manifold, but in this mode, there are problems such as poor uniform dispersion to each cylinder, and condensed water tends to accumulate inside the surge tank. Alternatively, there is a problem that the inner surface of the intake branch passage branched from the surge tank is easily soiled with carbon or the like.

Therefore, various proposals have been made to improve the dispersibility of EGR gas and countermeasures against condensed water. As an example, Patent Literature 1 discloses that an EGR gas recirculation passage is formed in a cylinder head, and EGR gas is jetted out to an intake port formed in the cylinder head.

Patent Document 1 incorporates an EGR gas recirculation passage in the cylinder head, so it has the advantage of evenly distributing the EGR gas to each intake port, and the EGR pipe can be eliminated or shortened, contributing to a more compact engine. There are advantages such as the advantage of being able to prevent or significantly suppress the generation of condensed water, and the advantage of being able to prevent the intake manifold from being contaminated with EGR gas.

Japanese Unexamined Patent Application Publication No. 2020-51361

Although Patent Literature 1 has the above advantages, there are also problems to be solved. For example, since many passages must be formed in the cylinder head, there is a problem that the processing of the cylinder head may be time-consuming. In addition to the intake port, the cylinder head has a cooling water jacket, a fuel injector, etc., and the EGR gas passage must be opened so as not to interfere with these, so the structure is undeniably complicated.

In particular, when two intake ports are formed independently corresponding to one cylinder and an injector is provided for each intake port, it is necessary to communicate the EGR gas passage with each intake port. There is a risk that the structure will become more complicated.

The invention of the present application was conceived in light of the current situation, and it is an object of the present invention to provide an intake manifold with an EGR distribution passage that is excellent in the function of treating condensed water.

The intake manifold of the present invention is
"A hollow structure is formed by overlapping and joining a plurality of shell-shaped members, and includes a surge tank, a plurality of intake branch passages branched from it and arranged in the direction of the cam axis, and EGR gas for each of the intake branch passages. and an EGR distribution passage for reflux,
Each of the intake branch passages has an upward portion where intake air flows upward, a vertex portion where the intake air changes direction, and a downward inclined portion where the intake air flows diagonally downward from the vertex portion toward the cylinder head. The downward inclined portion is composed of a twin passage portion located on the downstream side and divided into two by a partition wall, and a single passage portion located upstream of the twin passage portion,
The EGR distribution passage has a main distribution passage arranged at a position higher than the vertex of each of the branch passages and elongated in the cam axis direction, and branch distribution passages branched from the main distribution passage. The end of the main distribution passage and the end of the branch distribution passage serve as EGR gas outlets, and one EGR gas outlet opens into one intake branch passage from above.”
This is the basic configuration.

And in the above basic configuration,
"The EGR gas outlet of the EGR distribution passage is located at a portion closer to the top than the partition wall in the single passage portion of the downwardly inclined portion, and is open facing the partition wall."
It has the characteristics of

In the present invention, since the EGR distribution passage is formed integrally with the intake manifold, there is no manufacturing problem and it is highly practical. By appropriately setting the shapes and lengths of the EGR main passage and the EGR branch passages, the distribution amounts to the respective intake branch passages can be equalized, contributing to the stabilization of engine operation.

Since the EGR gas outlet opens toward the downward slope of the intake branch passage, even if condensed water is generated, it will not accumulate in the surge tank, and a large amount of water will flow into the cylinder at the time of starting, causing trouble. There will be no problems that cause Similarly, since the EGR gas does not enter the surge tank, the solid components contained in the EGR gas become a deposit in the surge tank together with the moisture, which separates due to vibration etc. and flows into the cylinder. There will be no problems that cause trouble.

Even if condensed water is mixed in the EGR gas, the condensed water is atomized by the flow of intake air on its way to the cylinder via the downward inclined portion of the intake branch passage and the intake port, and is discharged together with the exhaust gas. be done. Therefore, there is no problem in running the engine.

In addition, since the EGR gas ejected from the EGR gas outlet rides on the intake air, it is divided by the partition wall and directed to the twin passage, so a pair of intake ports formed in the cylinder head are provided with injectors. Injector type engines can also be handled without increasing the number of EGR gas outlets.

The fact that the EGR gas outlet is biased (offset) from the partition wall to the vertex side means that the EGR gas outlet is as far away from the intake port as possible. Even if exhaust gas blows back when the valve is open, the influence of the blow back can be suppressed to ensure the recirculation of EGR gas, and the solid components contained in the EGR gas can blow back. It is possible to prevent or greatly suppress the formation of deposits due to the heat of the exhaust gas and the adhesion and contamination of the inner surface of the downward slope portion. That is, it is possible to improve the distribution of EGR gas while maintaining the clean state of the downward inclined portion (and the intake port).

In addition, since the EGR gas outlet is as far away from the partition wall as possible, the EGR gas can be dispersed as much as possible into the intake air before the partition wall. be.

FIG. 2 is a view of an engine to which the intake manifold of the embodiment is attached, viewed substantially from the side; It is the figure which looked at the intake manifold from the substantially side. It is the figure which looked at the 1st shell-shaped member from the substantially side. FIG. 2 is a sectional view taken along line IV-IV of FIG. 1;

Next, embodiments of the present invention will be described based on the drawings. This embodiment is applied to an intake manifold for a three-cylinder engine for automobiles. The engine is installed in the engine room in a horizontal position with the crankshaft facing the vehicle width direction. Also, the engine faces the exhaust side in the forward direction of the automobile. Therefore, the engine is of the lateral, front exhaust type. The cylinder bore axis is tilted forward by a slight angle toward the forward direction of the vehicle.

In the following, the terms front-rear, left-right, and up-down are used to specify the direction, but the front-rear direction is the cam axis direction (crank axis direction), the left-right direction is a substantially horizontal direction orthogonal to the cam axis direction, and the up-down direction is the vertical direction. and Regarding front and rear, the side of the engine on which the timing chain is arranged is the front, and the side on which the transmission is arranged is the rear. Directions are clearly indicated in each figure as needed.

In FIG. 1, the engine is viewed from the intake side, and the engine comprises a cylinder block 1 and a cylinder head 2 fixed on its upper surface. A head cover 3 is fixed to the upper surface of the cylinder head 2 . A chain cover (front cover) 4 is fixed to the front surfaces of the cylinder block 1 , the cylinder head 2 and the head cover 3 .

An intake manifold 5 is fixed to the intake side surface 2 a of the cylinder head 2 . A throttle valve (throttle body) 6 is fixed to the rear end of the intake manifold 5 , and an intake duct 7 is connected to the throttle valve 6 . Reference numeral 8 in FIGS. 1 and 4 denotes a fuel delivery pipe that supplies fuel to the injector 9 (see FIG. 4).

(1). Basic structure of the intake manifold Although only a part is shown in FIG. 10, a second shell-shaped member 11, and a third shell-shaped member 12. By joining the overlapping shell-shaped members 10 to 12 by vibration welding or the like, an intake manifold having a hollow structure is formed. 5 is formed. Accordingly, each of the shell-shaped members 10 to 12 is an injection molded product of synthetic resin.

2 shows the entire intake manifold 5 viewed from the side, and FIG. 3 shows the entire first shell member 10 viewed from the side. In FIG. 2, the portion indicated by hatching sloping to the left is part of the first shell-shaped member 10, and therefore most of FIGS. The third shell-shaped member 12 and the second shell-shaped member 11 have almost the same outer shape.

Reference numeral 10 a shown in FIGS. 2 and 3 denotes a flange-like fastening portion provided on the first shell-like member 10 for fixing to the cylinder head 2 , and is exposed from the third shell-like member 12 . Reference numeral 13 in FIG. 2 denotes a negative pressure take-out port for the brake booster, and this negative pressure take-out port is formed in the second shell-shaped member 11 .

Although the first shell-shaped member 10 is shown in FIG. 3, the hatched portion in FIG. 2 It is joined with the shell-like member 11 . Accordingly, the second shell-shaped member 11 also has a superposed surface having the same shape as that of the first shell-shaped member 10 . Although FIG. 3 shows the overlapped surface as a simple flat surface, in reality, an annular groove is formed in the overlapped surface.

As can be understood from FIG. 3 , a recess constituting a surge tank 14 is opened in the first shell-shaped member 10 toward the side opposite to the cylinder head 2 . A receiving seat 16 to which the throttle valve 6 is fixed protrudes from a rear wall 15 of the first shell-shaped member 10 . Therefore, an intake inlet 17 is opened in the receiving seat 16 , and the intake air is jetted forward from the intake inlet 17 toward the surge tank 14 .

The surge tank 14 of the first shell-shaped member 10 extends downward, and the lower portion of the first shell-shaped member 10 has three lower outer grooves 19 for forming inlets of three intake branch passages 18. is shaped. On the other hand, an upper portion of the first shell-shaped member 10 located on the opposite side of the lower outer groove 19 across the recess is formed with a front-rear longitudinal flange 20 overlapping the intake side surface 2a of the cylinder head. In addition, three air intake outlet holes 21 are opened side by side in the cam axis direction.

As shown in FIGS. 1 and 4, the third shell-shaped member 12 has three outward-facing gutter-shaped portions 22 for forming the intake branch passages 18. The three outward-facing gutter-shaped portions 22 bulge toward the opposite side of the surge tank 14 and extend in the direction of the cam axis. are formed side by side. 4, the second shell-shaped member 11 has three inward gutter-shaped portions 23 overlapping with the outward gutter-shaped portion 22 to form the intake branch passage 18. They are formed side by side in the axial direction.

As indicated by the dotted line in FIG. 1 and the one-dot chain line in FIG. Three lower communicating holes 18a are formed to overlap with the lower portion of the shaped portion 22 .

As can be understood from the above description, the three intake branch passages 18 are formed by the first shell-shaped member 10, the second shell-shaped member 11, and the third shell-shaped member 12 at their inlets. , the outlet portion is mainly formed by the first shell-shaped member 10, and the portion between the inlet portion and the outlet portion is formed by the second shell-shaped member 11 and the third shell-shaped member 12. As shown in FIG. Therefore, the intake air that has flowed into the surge tank 14 mainly flows from the rear to the front, changes its direction downward at the front wall portion, and then flows into the lower communicating holes 18a of the respective intake branch passages 18. As shown by the dotted line arrow in , the direction is changed upward to reach the intake outlet hole 21, and as shown in FIG.

Therefore, each intake branch passage 18 is composed of an upward portion 24 where intake air flows upward, an apex portion 25 where the intake air changes direction, and a downward inclined portion 26 where the intake air flows obliquely downward. The downward sloping portion 26 is composed of a twin passage portion 26a positioned downstream and divided into two front and rear portions by a partition wall 27, and a single passage portion 26b positioned upstream of the twin passage portion 26a.

As shown in FIG. 4, the cylinder head 2 is formed with a pair of front and rear intake ports 28 corresponding to each cylinder. A pair of intake ports 28 are partitioned by a partition wall 29, and the partition wall 29 of the cylinder head 2 and the partition wall 27 of the intake manifold 5 are aligned in a straight line. Reference numeral 30 in FIG. 4 is a gasket.

A starting end portion of the partition wall 27 of the intake manifold 5 facing the single passage portion 26b is V-shaped in plan view in cross section. Therefore, the intake air is divided into the two twin passage portions 26a without resistance (without generating a swirl). The aforementioned intake air outlet hole 21 almost overlaps the downward slope 26 of the intake branch passage 18 .

Reference numeral 31 shown in FIG. 3 denotes a PCV recirculation passage 31 for recirculating the blow-by gas. An outlet 31 a of the PCV passage 31 opens downward generally toward the front-rear intermediate portion of the surge tank 14 . On the other hand, the inlet 31b of the PCV circulation passage 31 opens at a portion of the flange 20 of the first shell-shaped member 10 between the downwardly inclined portion 26 at the front end and the downwardly inclined portion 26 in the middle. Therefore, blow-by gas is supplied to the PCV circulation passage 31 from the PCV intermediate passage formed in the cylinder head 2 .

(2) EGR gas distribution structure As shown in FIGS. 1 and 2 (see also FIG. 4), an EGR distribution passage 32 is formed at a portion where the upper portions of the second shell-shaped member 11 and the third shell-shaped member 12 overlap. formed. In this case, the EGR distribution passage 32 is formed by forming a bulging groove in the third shell-shaped member 12, but it is also possible to form a groove in the second shell-shaped member 11 or to Both the member 11 and the third shell-shaped member 12 may be grooved.

The EGR distribution passage 32 is composed of an EGR main passage 32a extending from rear to front and two EGR branch passages 32b and 32c branching downward from the EGR main passage 32a. The EGR main passage 32a opens rearward, and is connected to an EGR valve or an EGR pipe (both not shown).

The end of the EGR main passage 32a and the end of the EGR branch passages 32b, 32c form an EGR gas outlet 33. The EGR gas outlet 33 at the front end opens in the downwardly inclined portion 26 at the front end, and the EGR gas outlet 33 at the rear end opens. is opened at the downward inclined portion 26 at the rear end, and the EGR gas outlets 33 at the front and rear intermediate portions are opened at the downward inclined portion 26 at the intermediate portion.

The relationship between the EGR gas outlet 33 and the intake branch passage 18 (downward inclined portion 26) is clearly shown in FIG. That is, the EGR gas outlet 33 opens from above the downward slope portion 26 on the downstream side of the vertex portion 25 of the intake branch passage 18 . It is arranged in a state that is greatly deviated to the side. Further, as schematically shown in FIG. 3, the EGR gas outlet 33 is arranged to face the partition wall 27 .

4 shows the cylinder bore in a vertical position. In this case, the vertical line passing through the vertex 25 is indicated by the dotted line 34. However, as described above, the present embodiment is applied. Since the engine has a slant type in which the exhaust side surface is tilted slightly forward, the vertical line passing through the vertex portion 25 actually becomes a one-dot chain line indicated by reference numeral 35 .

Also, condensed water may drop from the EGR gas outlet 33. In this case, when the cylinder bore is in a vertical position, the condensed water drops as indicated by the dotted arrow 36. Water falls as shown by the dashed-dotted arrow 37 (however, during operation, the condensed water is blown downstream along with the flow of intake air).

In any case, since the EGR gas outlet 33 is located downstream of the vertex 25 of the intake branch passage 18, the condensed water will not accumulate in the surge tank 14 regardless of whether the operation is in operation or after the operation is stopped. do not have. Therefore, the phenomenon that a large amount of condensed water accumulated in the surge tank 14 flows into the cylinder at the same time as the engine is started does not occur. Therefore, it is possible to prevent troubles at the time of starting caused by condensed water in a cold environment.

Although the EGR gas outlet 33 is located in the single passage portion 26b of the downwardly inclined portion 26, it is closer to the vertex portion 25 than the partition wall 27 in the single passage portion 26b. is open, even if the phenomenon of hot exhaust gas blowing back into the intake port occurs, the exhaust gas does not reach the EGR gas outlet 33, and therefore the solid portion contained in the EGR gas is It is possible to prevent the trouble of depositing by adhering to the inner surface of the downward inclined portion 26 due to high heat.

In addition, EGR gas travels to the intake port 28 along with the flow of intake air, but since a large distance can be secured from the EGR gas outlet 33 to the partition wall 27, the dispersibility of the EGR gas into the intake air is enhanced, and the two intake ports 28 It is possible to improve the uniform distribution of EGR gas to. As a result, the concentration of the air-fuel mixture is made uniform at the front and rear intake ports 28, and the stability of combustion can be improved.

Since the EGR distribution passage 32 is entirely located above the intake branch passage 18 , the condensed water does not accumulate in the EGR distribution passage 32 and the condensed water quickly falls to the downward slope portion 26 . Therefore, a phenomenon in which a large amount of condensed water accumulates in the EGR distribution passage 32 after the operation is stopped and flows into the cylinders at once when the engine is started does not occur. Even if condensed water is generated during operation, the condensed water is atomized on the intake air, so it does not adversely affect the operation. In other words, condensed water can be treated without problems by operation if it is little by little.

Although the embodiments of the present invention have been described above, the present invention can be embodied in various other ways. For example, the intake manifold may be a form in which two shell-shaped members are joined together. Also, the EGR distribution passage can be formed by joining dedicated members.

The present invention can be embodied in an engine intake manifold. Therefore, it can be used industrially.

2 cylinder head 5 intake manifold 6 throttle valve 10 first shell-shaped member 11 second shell-shaped member 12 third shell-shaped member 14 surge tank 18 intake branch passage 20 flange 21 intake outlet hole 24 upward portion 25 apex portion 26 downward inclined portion 26a twin passage portion 26b single passage portion 27 partition wall 28 intake port 32 EGR distribution passage 32a EGR main passage 32b, 32c EGR branch passage 33 EGR gas outlet

Claims (1)

A hollow structure is formed by overlapping and joining a plurality of shell-shaped members, and a plurality of intake branch passages branched from the surge tank and arranged in the cam axis direction, and EGR gas is recirculated to each of the intake branch passages. and an EGR distribution passage that allows
Each of the intake branch passages has an upward portion where intake air flows upward, a vertex portion where the intake air changes direction, and a downward inclined portion where the intake air flows diagonally downward from the vertex portion toward the cylinder head. The downward inclined portion is composed of a twin passage portion located on the downstream side and divided into two by a partition wall, and a single passage portion located upstream of the twin passage portion,
The EGR distribution passage has a main distribution passage arranged at a position higher than the vertex of each of the branch passages and elongated in the cam axis direction, and branch distribution passages branched from the main distribution passage. A terminal end of the main distribution passage and a terminal end of the branch distribution passage serve as EGR gas outlets, and one EGR gas outlet opens into one intake branch passage from above,
The EGR gas outlet of the EGR distribution passage is located in a portion of the single passage portion of the downwardly inclined portion that is closer to the top than the partition wall, and is open facing the partition wall.
engine intake manifold.

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