JPH0510203A - Cylinder head made of aluminum - Google Patents

Abstract

PURPOSE:To prevent a coolant passage from corrosion such as scale formation rusting, etc., enhance the heat radiation effect and preclude risk of heat cracking of a bulkhead. CONSTITUTION:A coolant passage 6 is bored straight in a bulkhead 5 between a suction and an exhaust port 3, 4, and in this passage 6 a heat radiation fin 11 is fitted which is made of a material humbler than Al in terms of potential and which has a greater surface area than the passage 6. The sacrifice anode action of this fin 11 prevents the inner surface 6a of the passage 6 from corrosion such as scale formation, rusting, etc., for a long period of time, while the cooling effect of the fin 11 precludes risk of heat cracking of the bulkhead 5, and thus the durability and reliability of a cylinder head 1 are enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum cylinder head, and more particularly to an aluminum cylinder head provided with an antiseptic anode material on an inner surface of a cooling water passage of the cylinder head.

[0002]

2. Description of the Related Art The lower surface of a cylinder head is thermally harsh, and in particular, the partition wall formed between the intake port and the exhaust port is thinner than the other parts of the cylinder head. It is placed in an environment where high thermal stress is generated when it is subjected to intense heating, and thermal cracks easily occur. Therefore, conventionally, a cooling water passage for circulating cooling water is formed in the partition wall, and the partition wall is cooled to protect the partition wall from thermal cracks. In addition, if this cooling water passage is used without rustproofing, corrosion scale or rust is generated on the inner peripheral surface of the cooling water passage, heat conduction is impeded, and effective cooling of the partition wall becomes impossible. Since it is a major obstacle to high output, it has been used in actual practice
As disclosed in No. 28, there has been studied a technique of forming a corrosion-resistant metal coating on the inner peripheral surface of a cooling water passage to prevent corrosion scale, rusting, etc., and to maintain thermal conductivity. However, when a cylinder head is made of aluminum that is electrically base due to the recent demand for smaller size and lighter weight, contact corrosion occurs between the aluminum and the corrosion resistant metal coating depending on the material of the corrosion resistant metal coating, Due to the problem that the strength of the partition wall is impaired, a proposal has been made to install the inner peripheral surface of the cooling water passage by inserting a pipe made of a metallic material that is a base material (No. 57-31544). ..

[0003]

However, by inserting the pipe, the distance between the cooling water channel and the partition wall becomes longer, so that the cooling efficiency is lower than when the pipe is not inserted, and the partition wall portion is excessively large. There is a risk that the thermal stress of (3) will be applied and a thermal crack will occur. In addition, the area of the characteristic anode of a material that is electrically base is limited to the inner surface of the pipe, so there is a limit to its capacity in the environment inside the drill hole where corrosion is accelerated and temperature is severe. , Has become a problem to be solved.

An object of the present invention is to provide a scale for cooling water passages,
It is to prevent corrosion such as rusting, improve the heat dissipation effect, and prevent thermal cracks in the partition walls.

[0005]

In order to solve the above-mentioned problems, the present invention perforates a partition wall between intake and exhaust ports to form a straight cooling water passage in the partition wall, and the cooling water passage is made of aluminum. Radiating fins that are more base in terms of electric potential and have a surface area larger than the surface area of the cooling water passage are fitted and provided.

[0006]

The partition formed between the intake and exhaust ports is thinner than the other parts of the cylinder head, and thermal cracks are likely to occur due to the thermal stress generated by the high temperature. Therefore, the partition wall is bored to form a linear cooling water passage in the partition wall, and a radiating fin that is more base than aluminum and has a surface area larger than the surface area of the cooling water passage is fitted into the cooling water passage. When the cooling water is circulated in the cooling water passage, the radiation fin serving as the sacrificial anode material prevents the inner surface of the passage from being corroded by the sacrificial action of positively flowing electrons to the low potential side (reference potential side). Further, since the surface area of the radiation fins, that is, the sacrificial anode area is larger than the surface area of the cooling water passage, its anticorrosion effect is better than in the conventional case, and the oxide film formation rate is also moderated. On the other hand, the radiating fins increase the cooling area, increase the cooling efficiency of the partition wall and the surrounding area of the partition wall, and lower the temperature of the partition wall and its surroundings, thus protecting from thermal cracks.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the accompanying drawings.

As shown in FIGS. 1 and 2, the cylinder head 1
Has an intake port 3 and an exhaust port 4 which are opened independently on the lower surface 2 of the cylinder head 1, and a partition wall 5 is provided between the intake port 3 and the exhaust port 4.
Are formed. As shown in FIG. 2, a cooling water passage 6 is formed in the partition wall 5 by linearly connecting one side and the other side of the cylinder head 1, and the cooling water passage 6 is formed in the cylinder head 1. The portion opened to the side is closed by a plug member 7 formed as a separate member. Further, a communication port 8 is formed on the lower surface 2 of the cylinder head 1 so as to communicate with the cooling water passage 6 on one side of the formation position of the intake port 3 and the exhaust port 4 on the cylinder head 1 side. There is. As shown in FIG. 2, the other end of the cooling water passage 6 communicates with a water jacket 9 defined in the cylinder head 1 through a port 10. Therefore, by connecting the communication port 8 to a cooling water circulation port (not shown) formed by opening in the upper surface of the cylinder body (not shown), the cooling water passage 6
The cooling water circulates between the cylinder body (not shown) and the water jacket 9 of the cylinder head 1 via the cooling water so that the partition wall 5 is effectively cooled by the cooling water flowing through the cooling water passage 6. become.

Such a cooling water passage 6 is shown in FIGS.
As shown in FIG. 5, in order to prevent scale, generated rust, etc., and maintain good cooling efficiency of the cooling water passage 6, a heat radiation fin 11 made of a sacrificial anode material is fitted and provided.

In the present invention, as a sacrificial anode material, a metal material which has a potential lower than that of aluminum (AC2B), such as zinc (Zn) or zinc-aluminum (Zn-Al JIS: 707).
S) is selected and the sacrificial anode material is molded to form, for example, a cross section as shown in FIG. 4, an N-shaped section as shown in FIG. 5, an M-shaped section as shown in FIG. It is formed with a water wheel cross section. For this molding method, extrusion molding or press molding is used, and the contour of the heat radiating fin 11 is processed into a size that can be press-fitted into the cooling water passage 6. Cooling fin 1
Press-fitting 1 includes shrink fitting by heating the cylinder head 1 and cooling fitting by cooling the fins 11 of the sacrificial anode material, and any one of the methods is adopted.

With the above structure, the heat radiation fin 11 press-fitted into the cooling water passage 6 causes electrons to flow to the low potential side (reference potential side), specifically, the ground side of the engine, and is itself entirely corroded. However, the inner peripheral surface 6a of the cooling water passage 6
Prevents the contact corrosion and prevents the scale, rust, and oxide film from growing in the portion in contact with the cooling water by the sacrificial anode function of the radiation fin 11 having the sacrificial anode working area larger than the inner peripheral surface 6a. On the other hand, the partition walls 5 are cooled well by the cooling from the heat radiation fins 11, and thermal cracks of the partition walls 5 are prevented, so that the durability and reliability of the cylinder head 1 are maintained.

By the way, in the above embodiment, the radiation fin 1
We explained that 1 is made of a metal material that is more electrically conductive than aluminum (AC2B) and has better thermal conductivity than aluminum, but as shown in Fig. 8, methods such as plating, thermal spraying, and press fitting of pipes are used. First, on the inner peripheral surface 6a of the cooling water passage 6, a sacrificial anode material (eg, zinc (Zn), zinc-aluminum (Zn-Al JIS: 707), which is lower in electric potential than aluminum, is formed.
5)) coating 12 is formed to a uniform thickness, and thereafter, aluminum or a material that is electrically baser than aluminum and has excellent heat conduction (for example, zinc (Zn),
The radiating fins 11 made of zinc-aluminum (Zn-Al JIS: 7075) may be integrally fitted.

When the surface area for performing the sacrificial anode action is increased by the coating film 12 and the cooling fins 11 as described above, the scale, rust, and oxide film on the portion contacting the cooling water grows as the surface area increases. Is effectively prevented over a long period of time, and at the same time, the partition wall 5 and the periphery of the partition wall 5 are well cooled by the cooling action of the heat radiation fins 11 and protected from thermal cracks. Therefore, the durability of the cylinder head,
Reliability is greatly improved.

The sacrificial anode material (eg, zinc (Zn) or zinc-aluminum (potentially zinc), which is lower in potential than aluminum, is first formed on the inner peripheral surface 6a of the cooling water passage 6 by a method such as plating, thermal spraying, and press fitting of a pipe. Zn-Al JIS: 7075)) Coating 1
2 may be formed to have a uniform thickness, and then the radiation fins 11 made of a material having excellent heat conduction such as aluminum may be integrally fitted in the cooling water passage 6. In addition to the N-shaped cross section and the water wheel-shaped cross section, the radiation fins 11 can be formed in various cross sections such as W, L, V, S, and Z. The contact area (surface area) with is larger than that of the inner peripheral surface 6a of the cooling water passage 6, and the shape is not particularly specified as long as it does not cause an extreme passage resistance to the cooling water passage.

[0015]

As is clear from the above description, according to the present invention, the following excellent effects are exhibited.

(1) The sacrificial anode action of the heat radiation fins can prevent corrosion such as scale and rust on the inner peripheral surface of the cooling water passage for a long period of time.

(2) Due to the cooling effect of the radiation fins, thermal cracking of the partition walls can be prevented and the durability and reliability of the cylinder head can be greatly improved.

[Brief description of drawings]

FIG. 1 is a sectional view of a cylinder head according to the present invention.

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

FIG. 3 is a detailed cross-sectional view of an essential part of the present invention.

FIG. 4 is a perspective view showing a cooling fin having a cross section according to the present invention.

FIG. 5 is a perspective view showing a cooling fin having an N-shaped cross section according to the present invention.

FIG. 6 is a perspective view showing a cooling fin having an M-shaped cross section according to the present invention.

FIG. 7 is a perspective view showing a cooling fin having a water turbine type cross section according to the present invention.

FIG. 8 is a detailed cross-sectional view of an essential part showing another embodiment according to the present invention.

[Explanation of symbols]

 3 Intake port 4 Exhaust port 5 Partition wall 6 Cooling water passage 6a Inner surface of cooling water passage 11 Radiating fin

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hirohito Eto, 3-25-1 Tonomachi, Kawasaki-ku, Kawasaki-shi, Kanagawa Isuzu Motors Co., Ltd. Kawasaki Plant (72) Inventor, Moriko 3 Tono-cho, Kawasaki-shi, Kawasaki, Kanagawa No.25-1 Isuzu Motors Co., Ltd. Kawasaki Plant (72) Inventor Masato Oguro 3-25-1 Tonomachi, Kawasaki-ku, Kawasaki City, Kanagawa Isuzu Motors Co., Ltd. Kawasaki Plant

Claims (1)

Claim: What is claimed is: 1. A partition between an intake port and an exhaust port is perforated to form a linear cooling water passage in the partition, and the passage has a lower potential than aluminum and a surface area of cooling water. A cylinder head made of aluminum, characterized in that radiating fins larger than the surface area of the passage are fitted and provided.