JPH06249059A - Cylinder head structure of internal combustion engine - Google Patents

Abstract

PURPOSE:To provide a structure of a cylinder head made of magnesium alloy which has sufficient strength for high temperature and corrosion resistance, and is very light in weight. CONSTITUTION:A member 20 made of aluminum alloy to form a cylinder 4, a combustion chamber 5, a suction port 6, and an exhaust port 7 is cast in the base material of magnesium alloy, constituting a cylinder head 1 integrated with a cylinder block. A flange part 27 having the screw boss to tighten an exhaust manifold is integrated with an exhaust port part 26 of the member 20 made of aluminum alloy. Similarly, a screw boss 23 to mount an ignition plug is provided on a combustion chamber part 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a magnesium alloy cylinder head for an internal combustion engine.

[0002]

2. Description of the Related Art When an internal combustion engine is mounted on a vehicle to power the vehicle, the weight of the vehicle greatly affects the fuel consumption of the engine. It is effective to reduce the weight of the vehicle to improve fuel efficiency, and it is also important to reduce the weight of the engine itself.

In conventional automobile internal combustion engines, the cylinder block and the cylinder head have been made of aluminum alloy to reduce the weight. In order to further reduce the weight, it is possible to use a magnesium alloy having a specific gravity much smaller than that of the aluminum alloy. However, the magnesium alloy has lower corrosion resistance than the aluminum alloy, and it cannot be said that the magnesium alloy has sufficient durability against corrosion of a portion exposed to combustion heat or exhaust heat.

In Japanese Patent Laid-Open No. 55-98632, the port liner 1 is attached to the exhaust port 102 as shown in FIG.
A method of manufacturing the cylinder head 101 in which 03 is cast is disclosed. Further, Japanese Utility Model Laid-Open No. 62-175254 discloses a method of manufacturing a cylinder head 111 in which a combustion chamber wall member 113 made of a steel plate is cast into a combustion chamber 112 as shown in FIG. Applying such a technology to a magnesium alloy cylinder head, if a metal liner that is heat resistant and resistant to corrosion is cast in the combustion chamber exposed to combustion gas and the exhaust port exposed to exhaust gas, it can be used under high temperature environment. The problem of corrosion resistance of can be solved.

[0005]

The current magnesium alloy is also inferior to the aluminum alloy in terms of high temperature strength, and its strength is significantly reduced at about 200 [° C.] as compared with the aluminum alloy. The cylinder head is partially 200
Since the temperature is higher than [° C.], it is necessary to make the structure of such a portion thick and to suppress the temperature rise by cooling.

However, when other members are attached to the cylinder head by bolts or the like, it is difficult to secure the strength of the thread of the screw boss provided on the cylinder head side due to the structure, and the stress at the time of fastening and the fastening object. A screw thread that receives a force due to vibration may be deformed at a high temperature when the strength is reduced.

Further, the magnesium alloy has a coefficient of thermal expansion which is twice as high as that of iron materials used for bolts and the like, and during repeated operation, the threads of the screw boss are fatigued by thermal stress, and high temperature strength is further increased. It may be lowered.

The conventional liner structure cannot solve the above problems.

An object of the present invention is to provide a structure of a magnesium alloy cylinder head which has sufficient high temperature strength and corrosion resistance and is extremely lightweight.

[0010]

In order to solve the above problems, a first invention provides an exhaust port member comprising an exhaust port portion forming an exhaust port and a flange portion having a screw boss for fastening an exhaust manifold. It is characterized in that it is integrally cast from an aluminum alloy, and the exhaust port member is cast into a base material of a magnesium alloy to form a cylinder head.

Next, a second invention is that a combustion chamber member having a screw boss for attaching a spark plug and forming a combustion chamber is cast from an aluminum alloy, and the combustion chamber member is made of a magnesium alloy. A casting cylinder head is formed in the material.

[0012]

The operation of the first invention will be described based on the above construction.

The exhaust port member made of an aluminum alloy forms the exhaust port to prevent the hot exhaust gas from directly contacting the magnesium alloy base material. Thereby, the corrosion resistance of the inner wall of the exhaust port in a high temperature environment can be secured.

The portion where the exhaust manifold is fastened by bolts or the like is the portion where the temperature easily rises due to exhaust heat, but the screw boss on the cylinder head side is
Since it is provided on the flange part of the aluminum alloy, it is easy to secure the strength of the screw thread.

The flange portion to which the exhaust manifold is attached is formed integrally with the exhaust port portion and cast into the cylinder head, so that the exhaust manifold can be supported with high strength.

Next, the operation of the second invention will be described.

A combustion chamber member made of an aluminum alloy forms a combustion chamber to prevent high temperature combustion gas from directly contacting a magnesium alloy base material. Thereby, the corrosion resistance of the inner wall of the combustion chamber in a high temperature environment can be secured.

Although the periphery of the combustion chamber is a portion where the temperature becomes high due to combustion heat, the screw boss for attaching the spark plug is provided in the aluminum alloy combustion chamber member, so that the strength of the screw thread can be easily secured.

The combustion chamber member forming the entire combustion chamber is securely supported and fixed in the base material.

Aluminum alloy is a lightweight material among those satisfying the corrosion resistance and high temperature strength required for the material of the cylinder head.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment according to the present invention will be described with reference to FIGS.
Will be described with reference to.

FIG. 1A is a view showing a cross section at the center of the intake / exhaust port, and FIG. 1B is a view showing a cross section at the center of a spark boss mounting screw boss.

Reference numeral 1 is a cylinder head integrated cylinder head made of magnesium alloy. Reference numeral 2 is a cylinder head portion, 3 is a cylinder block portion, 4 is a cylinder, 5 is a combustion chamber, 6 is an intake port, and 7 is an exhaust port.

Reference numeral 8 is an oil passage for cooling the cylinder portion.
Magnesium alloy causes corrosion when it is constantly in contact with water containing sodium or chlorine, and cannot be dealt with only by general rust prevention treatment. Therefore, in this embodiment, each part is cooled by oil. In oil cooling, the lubricating oil and the cooling liquid are common, it is not necessary to provide a water jacket on the cylinder head portion 2, and a core is not required when casting the cylinder head portion 2.

Reference numeral 9 is a camshaft mounting hole, 10 is a crankshaft mounting hole, and 11 is a crankcase.

Reference numeral 12 is a support member for suppressing lateral vibration of the cylinder 4. The support member 12 has a small hole that connects the oil passage 8 for cooling the cylinder portion and the crankcase 11. Further, the support member 12 is an after-installed member, and when the cylinder block part 3 is cast, the cylinder part cooling oil passage 8 and the crankcase 11 may be formed as a continuous space, and a core is required. Not.

The valve guide 13 and the valve seat 14 are
After each mounting hole is machined, it is attached by press fitting.

Reference numeral 20 denotes a member made of an aluminum alloy (hereinafter,
It is called an aluminum member. ), The outer peripheral surface of which has been subjected to heat-resistant electrical insulation treatment is cast into a magnesium alloy base material forming the cylinder block-integrated cylinder head 1. As the above-mentioned treatment, plasma sprayed ceramics, alumite treatment, other anodic oxidation treatment and the like can be considered. Since the magnesium alloy has low corrosion resistance and electrolytic corrosion occurs in a portion in contact with a dissimilar metal, the outer peripheral surface of the aluminum member 20 needs to be electrically insulated. Further, by making this electric insulation treatment heat resistant, it is possible to suppress the deformation of the aluminum member 20 during casting into the base material. If the outer peripheral surface of the aluminum member 20 before surface treatment is provided with small irregularities, good adhesion and heat transfer with the base material can be obtained.

The details of the aluminum member 20 will be described. The cylinder portion 21 forms the cylinder 4. Combustion chamber part 22
Form a combustion chamber 5. Further, the combustion chamber portion 22 is provided with a screw boss 23 for attaching a spark plug. The intake port portion 24 forms the intake port 6.
Further, the intake port portion 24 is integrally formed with a flange portion 25 provided with a screw boss for fastening the intake manifold. The exhaust port portion 26 forms the exhaust port 7. Further, the exhaust port portion 26 is integrally formed with a flange portion 27 provided with a screw boss for fastening the exhaust manifold.

In the aluminum member 20, the exhaust port member consisting of the exhaust port portion 26 and the flange portion 27, and the combustion chamber portion 22 as the combustion chamber member are integrally cast with the cylinder portion 21 and the intake port portion 24. It is a thing.

A high silicon aluminum alloy such as A390 is used for the aluminum member 20, and the inner wall of the cylinder 4 is treated with an alkaline chemical to ensure wear resistance. In the past, it was necessary to perform chemical treatment after masking the outer surface of the block that was not treated, but since magnesium alloys are not strongly affected by alkali,
The cylinder block-integrated cylinder head 1 can be dipped in a chemical as it is for processing. The finishing of the inner diameter of the cylinder 4 by machining is performed after the alkaline chemical treatment.

The spark plug post 15 is made of a steel pipe, and the inner and outer peripheral surfaces thereof are electrically insulated, and the spark plug mounting screw boss 23 is provided.
It is pressed into the upper part of.

Reference numeral 16 is a stud bolt for fastening the exhaust manifold to the cylinder head portion 2 and is attached to the flange portion 27. Details of this portion are shown in FIG. Reference numeral 28 denotes a screw boss provided on the flange portion 27.

FIG. 3A is a view showing a cross section at the center of the intake / exhaust port of the aluminum member 20, and FIG. 3B is a view showing a cross section at the center of the spark boss mounting screw boss.

The operation will be described based on the above configuration.

The exhaust port 7 is formed by the exhaust port portion 26 of the aluminum member 20, so that the high temperature exhaust gas does not directly contact the magnesium alloy base material. Thereby, the corrosion resistance of the inner wall of the exhaust port 7 in a high temperature environment can be secured.

The stud bolt 16 is attached to the flange portion 27 of the aluminum member 20. Since the aluminum alloy has sufficient high-temperature strength, even if the temperature of the flange portion 27 rises due to exhaust heat from the exhaust port 7, the thread of the screw boss 28 is not deformed and the stud bolt 16 is loosened. Can be prevented.

The flange portion 27 is formed integrally with the exhaust port portion 26, and can support the exhaust manifold with high strength.

The combustion chamber 5 is the combustion chamber portion 2 of the aluminum member 20.
It is formed of No. 2 and the high temperature combustion gas does not directly contact the magnesium alloy base material. Thereby, the corrosion resistance of the inner wall of the combustion chamber 5 in a high temperature environment can be secured.

The screw boss 23 for attaching the spark plug is provided in the combustion chamber portion 22 of the aluminum member 20. Therefore, the high temperature strength of the screw boss 23 is sufficient, and even if the screw boss 23 is subjected to stress, thermal stress, or the like at the time of attachment of the spark plug, the screw thread of the screw boss 23 is not deformed and the spark plug is prevented from loosening. You can

Compared with the case where an aluminum alloy member is cast only in the screw boss 23 and only the strength of the screw thread is secured, if the member forming the entire combustion chamber 5 is cast, the cast member is supported and fixed to the base material. Will be more certain. In the case of this embodiment, the cylinder portion 21, the combustion chamber portion 22, the intake port portion 2
4. Since the aluminum member 20 in which the exhaust port portion 26 and the flange portions 25 and 27 are all integrally formed is cast in the base material, the aluminum member 20 is firmly supported and fixed in the base material. .

In the case of this embodiment, both the valve guide 13 and the valve seat 14 are press-fitted and attached to the aluminum member 20. In particular, the position where the valve guide 13 and the valve seat 14 on the exhaust side are attached is a portion where the temperature becomes high, and attachment to an aluminum alloy member is effective in securing the supporting strength at high temperatures.

Functionally, the contact surface between the screw boss 23 and the spark plug cannot be electrically insulated, and if a magnesium boss is provided with a screw boss for mounting the spark plug, electrolytic corrosion cannot be avoided. Further, the spark plug is often attached and detached for maintenance, and it is more advantageous to provide the screw boss on the aluminum alloy portion in terms of wear. However, the aluminum member 20 is electrically isolated due to the electrical insulating treatment applied to the outer peripheral surface, and some kind of grounding means must be provided. In this embodiment, the ground wire is fastened together with the stud bolt 16 when mounting the exhaust manifold.

In this embodiment, the intake port 6 is also formed by the intake port portion 24 of the aluminum member 20, and the flange portion 25 for fastening the intake manifold is formed integrally with the intake port portion 24. The portion of the intake port 6 is not a particularly high temperature portion, but it is effective when it is necessary to increase the support strength of the intake manifold.

In a monoblock internal combustion engine in which the cylinder head portion 2 and the cylinder block portion 3 are integrally formed, it is not necessary to fasten them by head bolts. Monoblock is a magnesium alloy for which it is difficult to secure the strength of the fastening part that becomes high temperature.
This is a very advantageous structure.

Both the cylinder head portion 2 and the cylinder block portion 3 are of a structure that can be cast without using a core, and have good manufacturability. Alternatively, the aluminum member 20 may be regarded as a core, and a die may be used to manufacture the entire cylinder block-integrated cylinder head by die casting.

A second embodiment according to the present invention will be described with reference to FIGS.
Will be described with reference to.

FIG. 4A is a view showing a cross section at the center of the intake / exhaust port, and FIG. 4B is a view showing a cross section at the center of the spark boss mounting screw boss. The same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

Reference numeral 30 is a member made of an aluminum alloy (hereinafter referred to as an aluminum member). The combustion chamber section 32 forms the combustion chamber 5. Further, the combustion chamber portion 32 is provided with a screw boss 33 for attaching a spark plug. The exhaust port portion 36 forms the exhaust port 7. Also,
The exhaust port part 36 is integrally formed with a flange part 37 provided with a screw boss for fastening the exhaust manifold.

The aluminum member 30 is formed by integrally casting the exhaust port member consisting of the exhaust port portion 36 and the flange portion 37, and the combustion chamber portion 32 as the combustion chamber member.

The cylinder liner 31 is cast or press-fitted into the cylinder block portion 3 as a separate item.

Since the portion of the intake port 6 is not a particularly high temperature portion, even if this portion is formed of the magnesium alloy of the base material, there is no problem in corrosion resistance and strength.

In the case of this embodiment, since the aluminum member 30 and the cylinder liner 31 are separate bodies, different materials can be selected. For example, for the aluminum member 30 having a complicated shape, AC2A-F,
A material having excellent castability such as AC4B-F is used, and A390 alloy having excellent wear resistance is used for the cylinder liner 31. Alternatively, a method such as using a cast iron cylinder liner 31 may be considered.

[0054]

As described above, according to the present invention,
In the magnesium alloy cylinder head, cast an aluminum alloy member in the part exposed to the high temperature environment to prevent the magnesium alloy base material from directly contacting the combustion gas or exhaust gas. Sufficient high-temperature strength and corrosion resistance are secured by providing screw bosses at the fastening parts that require high-temperature strength. This makes it possible to realize a very lightweight magnesium alloy cylinder head.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment according to the present invention.

[Fig. 2] Similarly, a detailed view of the exhaust port side flange portion

[Figure 3] Similarly, a sectional view of an aluminum member

FIG. 4 is a sectional view showing a second embodiment according to the present invention.

FIG. 5 is a sectional view of the same aluminum member.

FIG. 6 is a view showing a conventional example in which a port liner is cast into an exhaust port.

FIG. 7 is a view showing a conventional example in which a combustion chamber wall member is cast into a combustion chamber.

[Explanation of symbols]

 1 Cylinder Block Integrated Cylinder Head 2 Cylinder Head Part 3 Cylinder Block Part 5 Combustion Chamber 7 Exhaust Port 20, 30 Aluminum Member 22, 32 Combustion Chamber Part (Combustion Chamber Member) 23, 33 Screw Boss 26, 36 Exhaust Port Part (Exhaust Port) Member) 27, 37 Flange part (exhaust port member)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location F02F 1/24 H 8503-3G 1/42 J 8503-3G

Claims (2)

[Claims] 1. An exhaust port member comprising an exhaust port portion forming an exhaust port and a flange portion having a screw boss for fastening an exhaust manifold is integrally cast from an aluminum alloy, and the exhaust port member is made of magnesium. A cylinder head structure for a natural engine, wherein a cast cylinder head is formed in an alloy base material. 2. A combustion chamber member having a screw boss for attaching a spark plug and forming a combustion chamber is cast from an aluminum alloy, and the combustion chamber member is cast into a magnesium alloy base material to form a cylinder head. A cylinder head structure of a natural engine, which is characterized by being formed.