JP2000161131A - Cylinder head structure for multiple-cylinder engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a cylinder head structure to stably supply EGR gas, although it has a compact structure with small number of parts items. SOLUTION: A collecting exhaust port 18 provided in a cylinder head 12 is composed of exhaust ports 46 extending from exhaust valve holes 35 of respective cylinders and an exhaust collecting part 47 in which the exhaust ports 46 are gathered. A rib 68 is provided to be projected from the side wall 121 of a projecting part 49 of the cylinder head 12 in which the exhaust collecting part 47 is formed, and a first EGR gas passage 66 formed in the rib 68 is connected to a second EGR gas passage 67 formed along the end face of the cylinder head 12. Since an inlet 661 of the first EGR gas passage 66 is opened in the exhaust collecting part 47 which is hard to be affected by inertia or pulsation of exhaust gas, EGR gas can be stably supplied.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention includes a collective exhaust port in which exhaust ports extending from a plurality of combustion chambers arranged along a row of cylinders are integrally collected by an exhaust collecting section formed inside a cylinder head. A cylinder head structure of a multi-cylinder engine.

[0002]

2. Description of the Related Art In general, an exhaust port formed in a cylinder head of a multi-cylinder engine performs only collection of exhaust gas discharged from a plurality of exhaust valve holes of the same cylinder inside a cylinder head, and is discharged from each cylinder. The collection of exhaust gases takes place in a separate exhaust manifold coupled to the cylinder head.

On the other hand, Japanese Patent No. 27098 discloses a system in which exhaust gas discharged from each cylinder is collected inside a cylinder head without using a separate exhaust manifold.
No. 15 publicly known. This cylinder head is
In order to ensure the durability even if a material having poor heat resistance is used, the entire circumference of a collective exhaust port that is integrally formed inside the cylinder head is surrounded by a water jacket to enhance cooling efficiency.

In order to reduce NOx contained in exhaust gas, an EGR device (exhaust gas recirculation device) that recirculates a part of the exhaust gas to an intake system is disclosed in, for example, Japanese Utility Model Publication No. 64-508.
No. 1 is known.

[0005]

In the above-mentioned conventional EGR system, the inlet of the EGR gas passage is opened at one of the exhaust ports of the multi-cylinder engine. There is a problem that it is difficult to supply the EGR gas at a stable pressure due to the inertia and the pulsation of the flowing exhaust gas. Further, since the EGR gas is taken out from the exhaust port upstream of the exhaust collecting portion in the exhaust manifold, there is a problem that the exhaust gas flows backward in the exhaust port depending on the flow rate of the EGR gas, thereby lowering the exhaust efficiency. Also, when extracting EGR gas from the exhaust manifold separate from the cylinder head, it is necessary to provide an EGR gas passage composed of a pipe for returning the EGR gas to the intake system. There was a problem that the score increased.

The present invention has been made in view of the above circumstances, and has a compact structure with a small number of parts.
It is an object of the present invention to provide a cylinder head structure of a multi-cylinder engine capable of stably supplying EGR gas.

[0007]

According to the first aspect of the present invention, an exhaust port extending from a plurality of combustion chambers arranged along a row of cylinders is provided inside a cylinder head. In a cylinder head structure of a multi-cylinder engine provided with a collective exhaust port formed integrally by an exhaust collecting portion formed in the cylinder head, an EGR gas passage for returning exhaust gas to an intake system is formed inside the cylinder head. A cylinder head structure for a multi-cylinder engine is proposed, wherein an inlet of a gas passage is opened to the exhaust collecting portion.

[0008] According to the above configuration, the inlet of the EGR gas passage is opened in the exhaust collecting portion where the exhaust ports extending from the plurality of combustion chambers are collected, so that the influence of inertia and pulsation of the exhaust gas is eliminated to remove the EGR gas. It can be supplied stably. In addition, since the EGR gas passage is formed inside the cylinder head, the E
The space and the number of parts can be reduced as compared with the case where the GR gas passage is provided.

According to the invention described in claim 2,
In addition to the configuration of claim 1, the exhaust collecting portion is formed inside a projecting portion projecting sideways from the cylinder head, and an EGR gas passage is formed in a rib provided along a side wall of the projecting portion. A cylinder head structure of a multi-cylinder engine characterized by being formed is proposed.

According to the above construction, the exhaust collecting portion is formed inside the projecting portion provided on the side surface of the cylinder head, and the EGR gas passage is formed in the rib provided along the side wall of the projecting portion. Further, the rigidity of the overhanging portion can be increased by the effect of reinforcing the ribs to reduce the vibration, and also increase in the size of the cylinder head can be suppressed.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on embodiments of the present invention shown in the accompanying drawings.

1 to 6 show an embodiment of the present invention. FIG. 1 is a longitudinal sectional view of a head portion of an engine, FIG. 2 is a sectional view taken along line 2-2 of FIG. 1, and FIG. 4 is a sectional view taken along line 4-4 of FIG. 2, FIG. 5 is a sectional view taken along arrow 5 in FIG. 2, and FIG. 6 is a sectional view taken along line 6-6 of FIG.

As shown in FIG. 1, an in-line three-cylinder engine E
Has a cylinder head 12 coupled to an upper surface of a cylinder block 11, and a head cover 13 is coupled to the upper surface of the cylinder head 12. A piston 15 is provided inside three cylinders 14 formed in the cylinder block 11.
Are slidably fitted, and a combustion chamber 16 is formed on the lower surface of the cylinder head 12 facing the upper surface of the piston 15. The intake ports 17 connected to the combustion chambers 16 are opened on the intake side of the cylinder head 12, and
A collective exhaust port 18 connected to the combustion chamber 16 is opened on the exhaust side of the cylinder head 12, and an exhaust pipe 19 is connected to this opening. An ignition plug insertion cylinder 21 for attaching and detaching the ignition plugs 20 is integrally formed with the cylinder head 12. Spark plug insertion tube 21 ... are inclined to the upper end collecting exhaust port 18 side with respect to the cylinder axis L _1, the thigh and the spark plug 20 is mounted to face the combustion chamber 16 at its lower end, to the upper end The ignition coil 22 is mounted.

A valve operating chamber 23 formed above the cylinder head 12 and covered by the head cover 13 has a camshaft 2 having an intake cam 24 and an exhaust cam 25.
6 and a rocker arm shaft 29 for swingably supporting the intake rocker arms 27 and the exhaust rocker arms 28.

The valve stems 32, 32 of the intake valves 31, 31, which open and close the two intake valve holes 30, 30 facing each combustion chamber 16, project into the valve operating chamber 23 and are mounted on the projections. The intake valves 31, 31 are urged by the valve springs 33, 33 in the valve closing direction. A roller 34 is provided at one end of each intake rocker arm 27 to contact the intake cam 24, and the other end contacts the upper ends of the valve stems 32, 32 of the intake valves 31, 31. Further, the valve stems 37, 37 of the exhaust valves 36, 36 for opening and closing the two exhaust valve holes 35, 35 facing the respective combustion chambers 16 project into the valve operating chamber 23, and the valves mounted on the projecting portions thereof. The exhaust valves 36, 36 are urged in the valve closing direction by the springs 38, 38. Each exhaust rocker arm 28
Is provided at one end thereof with a roller 39 which is in contact with the exhaust cam 25, and the other end is provided with a valve stem 37 of the exhaust valves 36, 36.
37 contacts the upper end.

Each of the intake ports 17 is provided with an injector 40 for injecting fuel into the intake valve holes 30, 30.
Is provided.

As shown in FIGS. 2 and 3, the three intake ports 17 extending from the three combustion chambers 16 are formed in a Y-shape, respectively.
Are cylinder heads 1 independently without assembling with each other
2 is opened on the side surface on the intake side. On the other hand, the collective exhaust port 18 is composed of a total of six exhaust ports 46 extending from the three combustion chambers 16 and an arched exhaust collecting part 47 in which the six exhaust ports 46 collectively. An exhaust outlet 48 to which the exhaust pipe 19 is coupled is formed at the center of the exhaust collecting part 47.

The cylinder head 12 facing the exhaust collecting part 47
The side wall 12 ₁ of the exhaust side and projecting outward curved in an arch shape, the side wall 11 ₁ of the cylinder block 11
And a projecting portion 49 protruding by a distance d. Therefore, the collective exhaust port 1 formed inside the overhang portion 49
8 is provided with an overhanging portion 49 which is curved in an arch shape.
It faces directly without going through the water jacket on the side wall 12 _1.

As described above, the exhaust collecting portion 47 of the collective exhaust port 18 formed inside the overhang portion 49 is
Since the side wall 12 ₁ of the faces directly without going through the water jacket, it is possible to compact cylinder head 12 as compared with the water jacket is interposed between the exhaust collecting section 47 and the side wall 12 _1. Moreover, since the side wall 12 ₁ is formed in an arch shape, not only allows more compact width of longitudinal end portions of the cylinder head 12 is reduced, contributing to the improved rigidity of the cylinder head 12 can do.

As apparent from FIGS. 2 and 4, the cylinder head 12 is formed with four bolt holes 50 on the intake side and the exhaust side, respectively. eight cylinder head fastening bolts 51 ₁ to 51 ₈ inserted from the cylinder block 1
The cylinder head 12 is fastened to the cylinder block 11 by screwing into the bolt holes 52 formed in the cylinder block 11.

Inside the collective exhaust port 18, two walls 53, 54 extend so as to partition between the center cylinder 14 and the cylinders 14, 14 on both sides. , 54 ₂ two cylinder head fastening bolts 51, 51 ₃ penetrates respectively. Two walls 53,
54 front end side of, i.e., two cylinder heads fastening bolt 51 _2, 51 exhaust collector 47 side than the _third, the oil return passage 55 _1, respectively, 55 ₂ passes.

The two walls 53 and 54 are provided at the collective exhaust port 1
8 is curved along the direction of the exhaust flowing through it, i.e. pointing towards the centrally located exhaust outlet 48, so that the two oil return passages 55 ₁ , 55 ₂ have two adjacent oil return passages 55 ₁ , 55 2. Bolts 51 ₂ , 5 for fastening cylinder heads
It is offset to the exhaust outlet 48 side relative to 1 _3. The above arrangement of the oil return passage 55 _1, 55 ₂ and the cylinder head fastening bolts 51 _2, 51 _3, a cylinder head 1
The exhaust resistance can be reduced by allowing the exhaust gas to flow smoothly in the collective exhaust port 18 while avoiding an increase in the size of the exhaust gas.

Also, three bosses 58 ₁ , 58 ₂ , 5 into which three bolts 57 for connecting the mounting flange 56 of the exhaust pipe 19 are screwed into the exhaust outlet 49 of the cylinder head 12.
8 ₃ but is formed, spaced cylinder bank L ₂ Direction 2
The two oil return passages 55 ₁ and 55 ₂ are deviated by a distance α in the direction of the cylinder row L _{2 with} respect to the boss portions 58 ₁ and 58 ₂ . Thus, another to approximate the wall portion 53 and the boss portion 58 _1, and the wall portion 54 and the boss portion 5
By increasing the rigidity of the vicinity of the exhaust outlet 49 of the cylinder head 12 by making the nozzles 8 and ₂ closer to each other, it is possible to prevent the cross-sectional area of the flow passage of the exhaust collecting part 47 from becoming small and to prevent an increase in exhaust resistance. it can.

Since the number of exhaust pipes 19 is one,
The two boss portions 58 ₁ and 58 ₂ on the lower side as viewed from above are not hidden below the exhaust pipe 19 and the two boss portions 5 1
8 _1, 58 ₂ fastening operation of the bolt 57 relative to can be performed easily. Further, by providing one boss portion 58 ₃ also on the upper side of the exhaust pipe 19, the exhaust pipe 19 can be fixed at three places and the mounting rigidity can be increased while securing the fastening workability of the bolts 57.

A cam drive chain chamber 59 for accommodating a cam drive chain (not shown) is formed at one longitudinal end of the cylinder head 12, and the cylinder head located on the opposite side of the cam drive chain chamber 59 is formed. the third oil return passage 55 ₃ is formed in the vicinity of the fastening bolt 51 _4. These two oil return passages 55 ₁ , 55 ₂ , 5
5 _3, the valve chamber 23 provided in the cylinder head 12, an oil return passage 60 formed in the cylinder block 11 ... through to communicate with the oil pan (not shown).

As described above, the two oil return passages 5
Since 5 ₁ and 55 ₂ are arranged in a region surrounded by the exhaust ports 46 of the adjacent cylinders 14 and the exhaust collecting portion 47, the oil is returned to the exhaust side of the cylinder head 12 without interfering with the collective exhaust port 18. Passages 55 ₁ , 5
5 ₂ it is possible to form the cylinder head 12
The oil in the valve operating chamber 23 can be reliably returned to the oil pan. Moreover, at low temperatures, the oil return passages 55 ₁ , 55
_Since the oil passing through ₂ can be heated by the exhaust gas passing through the collective exhaust port 18, it is possible to raise the temperature of the oil without providing a special oil heater and reduce the frictional resistance of each lubricating portion.

As is apparent from FIGS. 5 and 6, the three spark plug insertion cylinders 21 arranged at an angle on the exhaust side of the cylinder head 12 and the upper surface of the overhanging portion 49 are reinforced with a triangular cross section. Each is connected by walls 61. The rigidity of the overhang portion 49 is increased by the reinforcing walls 61, and the vibration of the overhang portion 49 during operation of the engine E can be effectively suppressed.

As shown in FIGS. 1 to 4, the interior of the cylinder head 12 water jacket J ₁ along the cylinder bank L ₂ is formed. Further, the cylinder head 12 which is heated to a high temperature by exhaust gas passing through the collective exhaust port 18
Are provided with water jackets J ₂ and J ₃ that respectively cover the upper and lower surfaces of the collective exhaust port 18. Portions that do not interfere with the exhaust ports 46, ie, 3
The upper and lower water jackets J ₂ and J ₃ near the three spark plug insertion cylinders 21 are three water jackets J.
₄ ... communicate with each other.

Thus, the area around the collective exhaust port 18 is
Water jacket J₁, J_Two, J _Three, J_FourCover with ...
As a result, the exhaust side of the cylinder head 12 that is likely to become hot
Can be cooled efficiently. In particular, auxiliary equipment that is sensitive to heat
As the ignition coil 22 and collective exhaust port
Water jacket J between 18_TwoIntervenes,
Effectively suppresses heat transfer to the ignition coil 22 ...
(See FIG. 6).

[0030] As is apparent from FIGS. 3 and 6, the outer portion of the collecting exhaust port 18, since the directly opposite side walls 12 ₁ of the protrusion 49 without passing through the water jacket, the casting of the cylinder head 12 Sometimes, the structure of the core for forming the water jackets J ₂ , J ₃ , J ₄ ... And the collective exhaust port 18 can be simplified.

First, a core for forming the water jackets J ₂ , J ₃ , J ₄ ... Is inserted into the mold in the direction of arrow A, and then a core for forming the collective exhaust port 18 is removed. In the same manner, the core is inserted in the mold in the direction of arrow A. At this time, an opening 62 exists between the upper and lower water jackets J ₂ and J _3. Can be inserted. The upper and lower water jackets J ₂ and J ₃ are connected to each other by _three water jackets J ₃ .
Since the cores corresponding to the three water jackets J ₄ alternately mesh with the portions corresponding to the six exhaust ports 46 of the core forming the collective exhaust port 18, interference between both cores is reduced. Avoided (see FIG. 2).

As described above, the water jackets J ₂ , J
_Since the core for molding ₃ , J ₄ ... Or the core for molding the collective exhaust port 18 can be assembled to the mold without dividing, the cost can be reduced when the cylinder head 12 is cast. Can be.

As is apparent from FIG. 2, a first EGR gas passage 66 and a second EGR gas passage 67 are formed in the cylinder head 12. Overhang 4 of cylinder head 12
9 of the arcuate side wall 12 _1, two ribs 6 extending in the longitudinal direction of the cylinder head 12 across the exhaust outlet 48
8, 69 are formed, and the first EGR gas passage 66 is formed inside one of the ribs 68 (see FIG. 3). First
The EGR gas passage 66 is formed on the side wall 12 of the arch-shaped overhang 49.
Since it is formed along ₁ , it is possible to suppress an increase in the size of the cylinder head 12 and an increase in vibration. Note that the other rib 69 does not include the EGR gas and functions simply as a reinforcing rib.

An inlet 66 at one end of the first EGR gas passage 66
Reference numeral ₁ denotes an opening near the exhaust outlet 48 of the exhaust collecting part 47, and the other end opens to the end face of the cylinder head 12 and is closed by a stopper 70. One end of the second EGR gas passage 67 formed along the end face of the cylinder head 12 is the first EGR gas passage 67.
Open to the other end near the GR gas passage 66 and the other end opened to the side wall 12 ₂ of the intake side of the cylinder head 12. The 2EGR opening into the side wall 12 ₂ of the intake side of the cylinder head 12
The gas passage 67 is connected to each of the three intake ports 17 via an EGR valve 71 that controls the flow rate of the EGR gas. The exhaust gas taken out from the collective exhaust port 18 is returned to the intake system through the first and second EGR gas passages 66 and 67 and the EGR valve 71, so that generation of NOx due to combustion is suppressed, and NO
x can be reduced.

As described above, the inlet 661 of the _first EGR gas passage 66 is opened in the exhaust collecting portion 47 which is hardly affected by inertia and pulsation of the exhaust gas because the plurality of exhaust ports 46 are gathered. EGR gas can be supplied stably while eliminating the effects of inertia and pulsation of the gas.
Further, since the first and second EGR gas passages 46 and 47 are formed integrally with the cylinder head 12, the space and the number of parts can be reduced as compared with the case where the EGR gas passage is provided by a separate member outside the cylinder head 12. . Two more
Because of this ribs 68 and 69 is protruded from the side wall 12 ₁ of the protrusion 49, it is possible to reduce vibration by increasing the rigidity of the projecting portion 49 at their ribs 68, 69. In particular, since the two ribs 68 and 69 connect the bosses 58 ₁ and 58 ₂ for attaching the exhaust pipe 19 to the end of the cylinder head 12, the rigidity of the exhaust pipe 19 can be improved. Has contributed.

Although the embodiments of the present invention have been described in detail above, various design changes can be made in the present invention without departing from the gist thereof.

For example, in the embodiment, the in-line three-cylinder engine E
However, the present invention can be applied to each bank of other in-line engines and V-type engines having different numbers of cylinders.

[0038]

As described above, according to the first aspect of the present invention, the inlet of the EGR gas passage is opened at the exhaust collecting portion where the exhaust ports extending from the plurality of combustion chambers are collected. EGR gas can be supplied stably while eliminating the effects of inertia and pulsation. Moreover, since the EGR gas passage is formed inside the cylinder head, the space and the number of parts can be reduced as compared with the case where an EGR gas passage made of a pipe is provided outside the cylinder head.

According to the second aspect of the present invention,
An exhaust collecting portion is formed inside the overhang provided on the side surface of the cylinder head, and an EGR gas passage is formed within the rib provided along the side wall of the overhang. By increasing the rigidity of the cylinder head, vibration can be reduced, and at the same time, the size of the cylinder head can be suppressed from increasing.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a head portion of an engine.

FIG. 2 is a sectional view taken along line 2-2 of FIG.

FIG. 3 is a sectional view taken along line 3-3 in FIG.

FIG. 4 is a sectional view taken along line 4-4 of FIG. 2;

5 is a view in the direction of arrows in FIG. 2;

FIG. 6 is a sectional view taken along line 6-6 in FIG. 5;

[Explanation of symbols]

12 Cylinder head 12 ₁ Side wall 16 Combustion chamber 18 Collective exhaust port 46 Exhaust port 47 Exhaust collecting part 49 Overhang 66 First EGR gas passage (EGR gas passage) 66 ₁ Inlet 68 Rib L ₂ Cylinder row

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3G024 AA09 AA11 BA01 BA25 DA01 DA03 DA06 DA09 DA18 DA19 DA20 FA00 FA01 FA14 GA04 3G062 AA03 ED13 ED14

Claims (2)

[Claims] An exhaust port (46) extending from a plurality of combustion chambers (16) arranged along a cylinder row (L ₂ ) is integrated with an exhaust collecting part (47) formed inside a cylinder head (12). Collecting exhaust port (1
8) In a cylinder head structure of a multi-cylinder engine provided with 8), an EGR gas passage (66) for recirculating exhaust gas to an intake system.
Is formed inside the cylinder head (12), and this EGR
A cylinder head structure for a multi-cylinder engine, characterized in that an inlet (66 ₁ ) of a gas passage (66) is opened to the exhaust collecting part (47). 2. The exhaust collecting portion (47) is formed inside a projecting portion (49) projecting sideways from a cylinder head (12), and a side wall (1) of the projecting portion (49) is formed.
2. The cylinder head structure for a multi-cylinder engine according to claim 1, wherein an EGR gas passage (66) is formed in a rib (68) provided along 2 ₁ ). 3.