JPH10122038A - Cylinder head structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sufficiently cool a cylinder head involving a recession defining a combustion chamber, an intake port and an exhaust port especially around the exhaust port. SOLUTION: A cylinder head 10 is formed with a first cooling passage 21 in the central portion thereof in the width direction above a recession 15, and a second cooling passage 221 laid therethrough from a second side face 10b to the first cooling passage 21. The second cooling passage 221 is arranged so as to adjoin an exhaust port at least its portion situated aside of the second side face 10b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder head having a recess forming a combustion chamber, an intake port and an exhaust port, and more particularly to a cooling structure using a cooling medium such as cooling water.

[0002]

2. Description of the Related Art As a cooling structure for a cylinder head, for example, there is one disclosed in Japanese Utility Model Publication No. Hei 1-118814. In this structure, a cooling structure is provided above a concave portion provided on the lower surface of the cylinder head to form a combustion chamber. A first cooling passage, a second cooling passage surrounding the recess, and a third cooling passage connecting the first and second cooling passages are provided in the cylinder head.

[0003]

In the vicinity of the exhaust port of the cylinder head during operation of the engine, the amount of heat transfer from the exhaust gas discharged is relatively large.
It is desired to efficiently cool the vicinity of the exhaust port. However, in the above-described conventional apparatus, no cooling passage is provided in the vicinity of the exhaust port, and if the vicinity of the exhaust port is sufficiently cooled. Is hard to say.

The present invention has been made in view of the above circumstances, and has as its first object to provide a cylinder head structure capable of sufficiently cooling the vicinity of an exhaust port.

Further, when a cooling passage through which a cooling medium flowing from the cylinder block side is provided in a cylinder head formed by die casting, machining after die casting is reduced as much as possible to reduce the number of processing steps. It is desired to reduce it.

Accordingly, the present invention is to provide a cylinder head structure in which a cooling passage can be easily formed by minimizing machining after die casting in a cylinder head formed by die casting. This is the second purpose.

[0007]

In order to achieve the first object, according to the first aspect of the present invention, there is provided a structure in which a piston is slidably fitted to a cylinder provided on a cylinder block. A recess forming a combustion chamber therebetween is provided on a lower surface of the cylinder head, and an intake port for passing an inner end through the recess and opening an outer end to a first side surface on one side in the width direction of the cylinder head. In a cylinder head structure provided with a cylinder head and an exhaust port for opening an outer end to a second side surface on the other side in the width direction of the cylinder head, a second portion located above the recess at the center in the width direction of the cylinder head. A first cooling passage and a second cooling passage penetrating from the second side surface of the cylinder head to the first cooling passage are provided in the cylinder head, and the second cooling passage is provided at least. It is formed close to the exhaust port in the portion of the second side surface closer.

Here, the term "close to the exhaust port" means a distance which can promote heat transfer between the cylinder head around the exhaust port and the cooling medium flowing through the second cooling passage. This refers to a state in which the second cooling passage is disposed between the second cooling passage and the exhaust port.

According to the first aspect of the present invention, the second cooling passage close to the exhaust port at least at a portion near the second side surface of the cylinder head communicates with the first cooling passage. The heat transfer between the cooling medium flowing through the second cooling passage and the cylinder head in the vicinity of the exhaust port is promoted, and the cooling air flowing through the first and second cooling passages when the engine is started. Synthetic resin is used to warm up the medium quickly and warm up the engine in a relatively short time, to efficiently cool the exhaust side valve seat, and to cool the vicinity of the high temperature exhaust manifold. It is possible to mitigate the thermal effect on the head cover made of the steel and the gasket between the head cover and the cylinder head.

According to the second aspect of the present invention, a bottomed screw hole for fastening the exhaust manifold is provided on the second side surface of the cylinder head, and the second cooling passage is located close to the screw hole. By being provided on the cylinder head,
It is possible to prevent the cylinder head from becoming excessively high in the vicinity of the screw hole, to alleviate fatigue of the material due to repeated low and high temperatures, and to prevent a decrease in fastening strength in the screw hole accordingly.

[0011] Here, "in the vicinity of the screw hole" means
This is a state in which the second cooling passage is arranged with a distance enough to prevent the cylinder head from becoming excessively hot near the screw hole with the exhaust port.

According to the third aspect of the present invention, a combustion chamber is formed between the cylinder and a top of a piston slidably fitted to a cylinder provided in the cylinder block. A recessed portion provided on the lower surface of the cylinder head, an intake port for passing the inner end through the recess and opening an outer end to a first side surface on one side in the width direction of the cylinder head; An exhaust port for opening the outer end to the second side surface on the other side in the width direction of the cylinder head is provided in the cylinder head formed by die casting. A first cooling passage formed at the time of die casting by a first core extending in the middle is provided above the concave portion at the center in the width direction of the cylinder head, and the first cooling passage is provided. A second cooling passage formed at the time of mold casting by a second core extending linearly substantially along the width direction from the second side surface of the second side surface is provided to penetrate from the second side surface to the first cooling passage, A plurality of third cooling passages formed by a third core extending linearly in a direction substantially orthogonal to the first and second cores at the time of die casting are formed from the mating surface of the cylinder head with the cylinder block. The cooling passage or the second cooling passage is provided so as to penetrate therethrough.

According to the configuration of the third aspect of the present invention, the first, second, and third cooling passages connected to each other are formed in the first and second cooling passages respectively corresponding to the cooling passages at the time of die casting of the cylinder head. It can be formed simultaneously by the first, second and third cores, and it becomes unnecessary to perform machining for forming the cooling passage on the cylinder head after casting the mold.

Further, according to the present invention, the portion of the exhaust port near the second side surface of the cylinder head can be pulled out in a direction parallel to the second core at the time of die casting of the cylinder head. Since the fourth core is formed into a shape that allows the fourth core to be formed, a part of the exhaust port can be simultaneously formed by the fourth core at the time of die casting, and the number of processing steps can be further reduced. it can.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below based on one embodiment of the present invention shown in the accompanying drawings.

FIGS. 1 to 6 show an embodiment of the present invention. FIG. 1 is a side view of a cylinder head viewed from the direction of arrow 1 in FIG. 2, and FIG. 2, FIG. 3 is a vertical sectional view of the cylinder head taken along line 3-3 in FIG. 2, FIG. 4 is a vertical sectional view of the cylinder head taken along line 4-4 in FIG. 2, and FIG. FIG. 6 is a plan view showing the arrangement of cores during die casting.

First, in FIGS. 1 to 4, this cylinder head 10 is formed for a four-cylinder internal combustion engine by die casting of an aluminum alloy, for example.
First to fourth cylinders 12 ₁ to 12 ₄ are fastened to the upper surface of the cylinder block 11 provided in parallel.

Each cylinder is provided with a cylinder
Da 12₁~ 12_FourSlidably fitted to each other
Recess forming a combustion chamber 14 with the top of the ton 13
15 are provided. Each cylinder head 10 has
Cylinder 12₁~ 12_FourFor example one by one
Corresponding intake ports 16 and each cylinder 12₁~ 12 _Four
For example, one exhaust port 17 corresponding to each one ...
Are provided. Thus, each intake port 16 is connected to each serial port.
12₁~ 12_FourCylinder head orthogonal to the array direction
Inside the recesses 15 in a plane along the width direction of the
And one side in the width direction of the cylinder head 10
Formed so as to open the outer end on the first side surface 10a
And each exhaust port 17 is located within a plane along the width direction.
Through the recesses 15 and the cylinder
An outer end is opened on the second side surface 10b on the other side in the width direction of the head 10.
It is formed in such a way that
12₁~ 12_FourAt the intake port 16 and the exhaust port
Ports 17...₁~ 12_FourIn the array direction
The inner ends are connected to the recesses 15 at positions shifted from each other along
It is arranged so that.

The cylinder head 10 has a plurality of plug mounting holes 18 for mounting the spark plugs (not shown) so that the tips of the spark plugs (not shown) can be inserted into the recesses 15 from the first side surface 10a of the cylinder head 10. , A plurality of press-fit holes 1 for press-fitting a guide cylinder for an intake valve which can be seated on a valve seat member 36 provided at the inner end of each intake port 16.
9 and a plurality of press-in holes 20 for press-fitting a guide cylinder for an exhaust valve which can be seated on a valve seat member 37 provided at the inner end of each exhaust port 17.
, 19 ..., 20 ... are perforated by machining after die casting of the cylinder head 10.

Referring also to FIG. 5, the cylinder head 1
The 0, to allowed to flow a cooling medium such as cooling water, the extending linearly substantially along the direction in the direction i.e. the arrangement direction of the cylinders 12 ₁ to 12 ₄ substantially orthogonal to the width direction of the cylinder head 10 1 a cooling passage 21, a plurality of second cooling passages 22 ₁ ... extending linearly in a direction substantially along the width direction of the cylinder head 10, and 22 _2, the first cooling passage 21 and the second cooling passage 22 ₁ ..., 22 ₂ There plurality of third cooling passage 23 ₁ ... extending substantially perpendicular to the direction i.e. the vertical direction to the extending direction, respectively, 23 ₂ ..., 23 ₃ ..., 23 ₄ ... and are provided.

The first cooling passage 21 is provided in the cylinder head 10
Width direction in each recess 15 ... upper at the center are those formed to extend along the arrangement direction of the cylinders 12 ₁ to 12 _4, the cylinder head along the arrangement direction of the cylinders 12 ₁ to 12 ₄ 10 at both ends of the first cooling passage 21
Are open at both ends. Thus, the cylinder head 10
Lid member for closing one end of the first cooling passage 21 (not shown)
And an outlet pipe (not shown) communicating with the other end of the second cooling passage 21 is connected.

Second cooling passage 22₁…, 22_TwoIs a shirin
The first cooling passage 21 from the second side surface 10b of the
The second cooling
Passage 22₁... are the first and second cylinders 12₁, 12
_TwoBetween the exhaust ports 17, 17 corresponding to
And third cylinder 12_Two, 12_ThreeCorresponding to each
Between the air ports 17, 17 and the third and fourth syringes
Da 12_Three, 12_FourExhaust ports 17 respectively corresponding to
17 and the second cooling passage 22 _TwoIs the
1 cylinder 12₁The exhaust port 17 at the
Reception passage 22₁And is located at a position sandwiched therebetween. And the second
2 cooling passage 22₁…, 22_TwoThe outer end to the cylinder
To open the second side surface 10b of the pad 10
However, at least in the portion near the second side surface 10b,
Each exhaust port so that it goes under the air port 17.
G are formed in a shape close to 17. As a result,
Cylinder head 10 and second cooling around air port 17.
Reception passage 22₁…, 22_TwoThe contact surface with the cooling medium flowing through
The cylinder around the exhaust port 17 ...
The head 10 can be cooled more effectively.

By the way, the second side surface 10b of the cylinder head 10, an exhaust manifold 25 communicating with the exhaust ports 17 ... ₁ ... second cooling passages 22 are fastened so as to close the outer end opening of 22 ₂ The exhaust manifold 25 is provided on the second side surface 10 b of the cylinder head 10.
A plurality of bottomed screw holes 26 ... are provided for allowing fastening the second cooling passage 22 ₁ ..., 22 ₂ are formed so as to be closer to those of the screw holes 26 ....

The third cooling passages 23 ₁ , 23 ₂ , 23 ₃
, 23 ₄ ... are provided so as to penetrate from the mating surface 24 of the cylinder head 10 to the cylinder block 11 to the first cooling passage 21 or the second cooling passages 22 ₁ ... 22 ₂ . Third cooling passages 23 ₁ ..., 2
3 ₂ …, 23 ₃ …, 23 ₄ …
Open end of the 4 so as to surround the respective cylinder 12 ₁ to 12 ₄ are arranged so as to communicate the upper end of the cooling passage 27 provided in the cylinder block 11.

[0025] In Thus, the third cooling passage 23 ₁ ... are their upper end the second cooling passage 22 ₁ ..., as providing communication respectively 22 _2, the second side surface of the cylinder head 10 10b and the recesses 15 ... it is located between, is formed in each cylinder 12 ₁ to 12 ₄ and an arc shape with the same central. ₂ ... The third cooling passage 23, as establishing communication respectively their upper both ends of the first cooling passage 21, provided in pairs at both ends of the cylinder head 10 along the arrangement direction of the cylinders 12 ₁ to 12 ₄ Can be Third cooling passage 23
₃ ... is as establishing communication respectively their upper to the first cooling passage 21, is disposed in three places of the portion of the first side surface 10a side of the cylinder head 10 between the recesses 15 ... mutually. Further, the third cooling passages 23 ₄ are formed such that their upper ends communicate with the first cooling passages 21 and their side portions communicate with the second cooling passages 22 ₁ . Head 1
0 are disposed at three places near the second side surface 10b.

In FIG. 6, when the cylinder head 10 is cast into a mold, the first cooling passage 21 is formed of a pair of first cores 31 ₁ , 31 extending linearly in a direction substantially orthogonal to the width direction of the cylinder head 10. ₂ and the first cores 31 ₁ and 31 ₂ are formed by these 31 ₁ and 31 2
_{The two} inner ends are arranged to contact each other. Moreover, the concave portion 38 ₁ and the convex portion 3 are provided at the inner end of the first core 31 _1.
9 ₁ is provided in the first inner end of the core 31 ₂ recesses 38 ₂
And the projecting portion 39 ₂ is provided, the convex portion 39 ₂ of the first core 31 ₂ is fitted into the recess 38 of the _first core 31 _1,
The first core 31 _{and second} recesses 38 ₂ to the first core 31 _{of the} projecting portion 3
9 ₁ is fitted. Thus, both first cores 31 ₁ , 3
By projection fitting a _second inner end portion, it is possible to exert a labyrinth effect during die casting of the cylinder head 10, Ya burrs at the inner end contact portion of both the first core 31 _1, 31 ₂ The occurrence of insertion can be prevented.

Further the outer end portions of the first core 31 _1, 31 _2, ampulla 40 ₁ overhanging on both sides in the width direction of the cylinder head 10, 40 is formed as a _2, these ampulla 40 _1, 40 ₂ makes it possible to the flow area of the cooling medium in the cylinder head 10 as much as possible to increase further facilitate cooling of the cylinder head 10. In particular, the first cylinder 1
The exhaust port 17 corresponding to the 2 ₁ is disposed between the second cooling passage 32 _2, 32 ₁ on both sides thereof, the second and third cylinder 12 _2, 12 ₃ to the exhaust port corresponding 17 ...
The second cooling passage 32 of their sides _1, 32 while being disposed respectively between _1, an exhaust port 17 corresponding to the fourth cylinder 12 _4, the second cooling passage 3 on one side
2 ₁ is only are arranged, the fourth cylinder 12 ₄
There is a possibility that cooling is insufficient exhaust ports 17 corresponding to, by ampulla 40 ₂ of the first core 32 ₂ is located at the other side of the exhaust port 17 corresponding to the fourth cylinder 12 ₄ , it is possible to compensate for the cooling by the cooling medium of the exhaust port 17 corresponding to the fourth cylinder 12 _4. Thus to ampulla 40 _1, 40 _2, both the first core 3 during die casting completion
1 _1, 31 ₂ may be formed to allow the shape to be pulled out from the mold in a direction away from each other a.

The second cooling passages 22 _1, ..., 22 ₂ are provided with a second core 32 extending along the width direction of the cylinder head 10.
₁ …, 32 ₂ , respectively.
The second core 32 ₁ ... inner ends of are arranged so as to be fitted respectively in the recess 41 ₁ ... provided in the first core 31 _1, 31 _2, a second inner end of the core 32 ₂ is possible to pull out from the first arranged manner is fitted in the recess 41 ₂ provided in the core 31 _1, the mold toward the other side at the time of die casting completion along the width direction of the cylinder head 10 The shape is formed as follows. Thus the second core 32 ₁ ... and 32 by the inner end and the two first cores 31 ₁ of _2, 31 and _second side concave-convex fitting, labyrinth effect during die casting of the cylinder head 10 And the second core 32 ₁ …,
It is possible to prevent the occurrence of burrs and insertions at the contact portion between the _second core 32 ₂ and the first cores 31 ₁ and 31 ₂ .

The third cooling passages 23 ₁ , 23 ₂ , 23 ₃
..., 23 ₄ ..., the third core 33 extending vertically ₁ ...,
33 ₂ ..., 33 ₃ ..., 33 ₄ ... are formed respectively by a third core 33 ₁ ... the upper second core 32 ₁ ..., 32
₂ and the third core 33
₂ ..., 33 ₃ ... are arranged so as to contact the upper end to the first core 31 _1, 31 _2, third core 33 ₄ ... along with contacting the upper end to the first core 31 _1, 31 ₂ It is arranged so that the side surface may contact the second cores 32 ₁ . Moreover, all the third cores 33 ₁ …, 33 ₂ …, 33 ₃ …, 3
3 ₄ ... is formed to allow the shape to be pulled out from the mold downward of the cylinder head 10 during mold casting ended.

Paying particular attention to FIG. 4, each exhaust port 17.
The portion of the cylinder head 10 close to the second side surface 10b is the second core 32 during the die casting of the cylinder head 10.
₁ ..., fourth that made it possible to pull the 32 ₂ parallel direction
The fourth core 34 is formed by the core 34 and is not limited to a linear shape, and may be any shape as long as the fourth core 34 can be pulled out from the mold.

Next, the operation of this embodiment will be described.
And each recess 15 at the center in the width direction of the cylinder head 10.
Cooling passage 21 located above the cylinder head, and a cylinder head
10 from the second side surface 10b to the first cooling passage 21
Second cooling passage 22₁…, 22 _TwoAnd cylinder head 1
0, the second cooling passage 22₁…, 22_TwoIs a small
At least in the portion near the second side surface 10b, the exhaust port 17
Are formed in a shape close to. Therefore, the second cold
Reception passage 22₁…, 22_TwoThrough the cooling medium and exhaust port
Heat transfer with the cylinder head 10 around the
To quickly raise the temperature of the cooling medium when the engine starts.
The engine can be warmed up in a relatively short time
In addition, the exhaust side valve seat member 37 is efficiently cooled.
Exhaust manifold that is capable of high temperature
In addition to cooling the vicinity of
Head cover and head cover and cylinder head
To reduce the heat effect on the gasket between
Can be.

A screw hole 26 with a bottom for fastening the exhaust manifold 25 is provided in the second side face 10b of the cylinder head 10, and the second cooling passages 22 ₁ .
₂ is formed in a shape close to the screw holes 26..., Thereby avoiding the cylinder head 10 becoming excessively high in the vicinity of the screw holes 26. Can be alleviated, and accordingly, a decrease in fastening strength in the screw holes 26 can be prevented.

Further, the first cooling passage 21 or the second cooling passage 22 is formed in the cylinder head 10 from the mating surface 24 of the cylinder head 10 with the cylinder block 11.
₁ ..., a plurality of third cooling passage 23 penetrating to the 22 _2
1 ..., 23 ₂ ..., 23 ₃ ..., 23 ₄ ... are provided, the second cooling passage 22 a cooling medium which has been circulated from the cooling passage 27 from the third cooling passage 23 ₁ ... of the cylinder block 11 ₁ ..., 22 or ₂ through the circulating in the first cooling passage 21, the third cooling passage 23 ₁ ..., 23 ₂ ..., 23 ₃ ...,
It is possible to cool the cylinder head 10 from 23 ₄ ... so as to flow into the first cooling passage 21. Moreover, such cooling passages 21, 22 ₁ ..., 22 ₂ , 23 ₁ ...,
23 ₂ ..., 23 ₃ ..., 23 ₄ ..., the cylinder head 10
Cores 31 ₁ , 31 ₂ , 32 ₁ … 3
2 _2, 33 ₁ ..., 33 ₂ ..., 33 ₃ ..., 33 ₄ ... are those formed by the respective cooling passages 21, 22 ₁ ..., 2
2 _2, 23 ₁ ..., 23 ₂ ..., 23 ₃ ..., 23 ₄ ... communicating portion includes cores 31 _1, 31 _2, 32 ₁ ..., 32 _2, 33 ₁
..., 33 ₂ ..., 33 ₃ ..., 33 ₄ ... so are those formed by the mutual contact of the cooling passages 21, 22 ₁ ..., 2
2 _2, 23 ₁ ..., 23 ₂ ..., 23 ₃ ..., the cylinder head 10 machined to form a 23 ₄ ... after die casting
It is not necessary to perform this process, and the number of processing steps can be reduced.

[0034] In yet an exhaust port 17 ..., which second side surface 10b side of the portion of the cylinder head 10, second core 32 ₁ ... are formed as enabling 32 ₂ and formed by the fourth core 34 parallel By forming a part of the exhaust ports 17 at the time of die casting, the number of processing steps can be further reduced.

Although the embodiments of the present invention have been described in detail, the present invention is not limited to the above embodiments, and various design changes can be made without departing from the present invention described in the appended claims. It is possible to do.

For example, the present invention is not limited to a cylinder head for a multi-cylinder internal combustion engine, but is also applicable to a cylinder head for a single cylinder internal combustion engine. It may be formed by a core, and furthermore, an intake port 16 and an exhaust port 17
Can also be applied to a cylinder head provided with a plurality of cylinders.

[0037]

As described above, according to the first aspect of the present invention, heat transfer between the cooling medium flowing through the second cooling passage and the cylinder head near the exhaust port is promoted, and At the time of startup, the temperature of the cooling medium flowing through the first and second cooling passages can be quickly raised to warm up the engine in a relatively short time, and the exhaust-side valve seat can be efficiently cooled. At the same time, by cooling the vicinity of the exhaust manifold where the temperature becomes high, it is possible to reduce the thermal influence on the head cover made of synthetic resin, the head cover, and the gasket of the cylinder head.

According to the second aspect of the present invention, it is possible to prevent the cylinder head from becoming excessively high in the vicinity of the screw hole, thereby alleviating the fatigue of the material due to the repetition of low and high temperatures. A decrease in fastening strength at the hole can be prevented.

According to the third aspect of the present invention, the first, second, and third cooling passages connected to each other are formed into the first, second, and third cooling passages corresponding to the cooling passages at the time of die casting of the cylinder head. By forming the cooling passages at the same time by the third core, it is not necessary to perform machining for forming the cooling passage on the cylinder head after casting the mold, and the number of working steps can be reduced.

Further, according to the present invention, a part of the exhaust port is simultaneously formed by the fourth core at the time of die casting, so that the number of processing steps can be further reduced.

[Brief description of the drawings]

FIG. 1 is a side view of a cylinder head as viewed from a direction indicated by an arrow 1 in FIG.

FIG. 2 is a bottom view as viewed in the direction of arrow 2 in FIG.

FIG. 3 is a longitudinal sectional view of the cylinder head taken along line 3-3 in FIG. 2;

FIG. 4 is a longitudinal sectional view of the cylinder head taken along line 4-4 in FIG. 2;

FIG. 5 is a sectional view taken along line 5-5 of FIG. 3;

FIG. 6 is a plan view showing an arrangement of cores during die casting.

[Explanation of symbols]

10 second side surface 11 ... cylinder block 12 of the _first side surface 10b ... cylinder head ... cylinder head 10a ... cylinder head, 12 _2, 12 _3, 12 ₄ ... cylinder 13 ...・ Piston 14 ・ ・ ・ Combustion chamber 15 ・ ・ ・ Recess 16 ・ ・ ・ Intake port 17 ・ ・ ・ Exhaust port 21 ・ ・ ・ First cooling passage 22 ₁ , 22 ₂・ ・ ・ Second cooling passage 23 ₁ , 23 ₂ , 23 _3, 23 ₄ ... third cooling passages 24 ... mating surface 25 ... exhaust manifold 26 ... screw hole 31 _1, 31 ₂ ... first core 32 _1, 32 ₂ ...・ Second core 33 ₁ , 33 ₂ , 33 ₃ , 33 ₄ ... third core 34 ... fourth core

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tamotsu Ito 1-4-1, Chuo, Wako-shi, Saitama

Claims (4)

[Claims] A combustion chamber (14) is provided between a top of a piston (13) slidably fitted to cylinders (12 ₁ , 12 ₂ , 12 ₃ , 12 ₄ ) provided in a cylinder block (11). ) Is formed in the cylinder head (1).
A suction port (16) provided on the lower surface of the cylinder head (0) and having an inner end passed through the recess (15) and having an outer end opened on a first side surface (10a) on one side in the width direction of the cylinder head (10); A cylinder head (10) provided with an exhaust port (17) for passing an inner end through the recess (15) and opening an outer end on a second side surface (10b) on the other side in the width direction of the cylinder head (10). In the structure, the first cooling passage (21) located above the recess (15) at the center in the width direction of the cylinder head (10).
And a second cooling passage (22) penetrating from the second side surface (10b) of the cylinder head (10) to the first cooling passage (21).
₁ , 22 ₂ ) are provided on the cylinder head (10),
The second cooling passage (22 _1, 22 ₂₎ is a cylinder head structure which is characterized by being formed in proximity to the exhaust port (17) at a portion of at least the second side face (10b) closer. 2. A second side face (1) of a cylinder head (10).
0b) is provided with a bottomed screw hole (26) for fastening the exhaust manifold (25), and the second cooling passage (21)
₁ , _{2 1} ) is provided in the cylinder head (10) adjacent to the screw hole (26).
The described cylinder head structure. And a cylinder block (11) provided on the cylinder block (11).
Cylinder (12₁~ 12_Four) That can be slidably fitted to
Forming a combustion chamber (14) with the top of the ton (13)
A recess (15) is provided on the lower surface of the cylinder head (10).
Through the inner end of the recess (15).
First side surface (10a) on one side in the width direction of the magnetic head (10)
An intake port (16) for opening an outer end of the intake port;
(15) Let the inner end pass through and the cylinder head
Open the outer end on the second side (10b) on the other side in the width direction of (10).
The exhaust port (17) to be opened is shaped by die casting
Cylinder provided on cylinder head (10) formed
In the head structure, the width direction of the cylinder head (10)
The first core (3) extending linearly in a direction substantially orthogonal to
1₁, 31_Two), The first cold formed during die casting
The recirculation passage (21) is located in the width direction of the cylinder head (10).
The cylinder head is provided in the center above the recess (15).
(10) substantially along the width direction from the second side surface (10b).
The second core (32₁, 32_TwoBy)
The second cooling passage (22) formed at the time of die casting₁, 22
_Two) From the second side surface (10b) to the first cooling passage (2).
1) and the first and second cores (31
₁, 31_Two; 32₁, 32_Two)
A third core (33) extending linearly₁, 33_Two, 33_Three, 33
_Four), A plurality of third cooling passages formed during die casting.
Road (23₁, 23_Two, 23_Three, 23_Four) To the cylinder
Mating surface of cylinder (10) with cylinder block (11)
(24) The first cooling passage (21) or the second cooling passage (21)
Reception passage (22₁, 22 _Two)
A cylinder head structure. 4. A portion of the exhaust port (17) near the second side surface (10b) of the cylinder head (10),
The cylinder head (10) is formed into a shape that can be formed by the fourth core (34) that can be pulled out in a direction parallel to the second cores (32 ₁ , 32 ₂ ) during die casting of the cylinder head (10). 4. The cylinder head structure according to claim 3, wherein: