JPS593144A - Manufacture of cylinder head - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a cylinder head for an internal combustion engine, and more particularly to a method of manufacturing a cylinder head in which a heat-resistant plate for preventing cracks between valves is cast and attached.

The cylinder head is attached to the cylinder block so as to close one end of the cylinder, and together with the piston, forms a combustion chamber consisting of a sealed space. The cylinder head has an intake bow 1 and an exhaust bow opening on the surface facing the combustion chamber.
An intake valve and an exhaust valve are attached to these spaces [1]. The area between the intake boat and the exhaust boat where these pair of valves are installed, the area between the Zunawara valves, receives a large heat load due to combustion explosion, and this area is said to be prone to cracking due to the heat load. There's a problem.

In order to prevent such intervalve cracks, it is conceivable to form the entire cylinder head from a heat-resistant metal, but such a measure would significantly increase the cost of the cylinder head. So, for example, Jikko Sho 47-220
No. 06 discloses a cylinder head in which a heat-resistant plate is integrally cast between the valves. This heat-resistant plate is embedded in the base material forming the cylinder head so as not to be exposed on the surface facing the combustion chamber between the pair of valves. Therefore, with this configuration, the heat-resistant plate is not exposed on the surface facing the combustion chamber, so the heat-resistant effect is not sufficiently exhibited, and the heat-resistant plate is embedded in the base material, which causes problems in casting. It has the disadvantage that positioning and holding of the heat-resistant plate during actual use is extremely difficult.

Therefore, for example, a flat heat-resistant plate is placed on the upper surface of the sand mold support that forms the cylinder head, and the cylinder head is cast by casting the heat-resistant plate into the cylinder head. It becomes possible to expose it to the facing surface. However, with this method, the temperature locally drops at the boundary between the top surface of the sand mold receiver and the edge of the heat-resistant plate, which impairs the flow of the molten metal, and as a result, the heat-resistant plate and cylinder This results in the disadvantage that the connection with the head cannot be achieved reliably.

The present invention has been made in view of these problems.The heat-resistant plate and the base material of the cylinder head are reliably bonded, and the heat-resistant plate is exposed on the surface facing the combustion chamber. It is an object of the present invention to provide a method for manufacturing a cylinder head that provides high heat resistance, particularly to the portion between the valves.

The present invention will be explained below with reference to an illustrated embodiment.

FIG. 1 shows a heat-resistant plate 1 that is incorporated into the cylinder head of this embodiment. This heat-resistant plate 1 is made of a material that is highly compatible with casting into a cylinder head made of cast iron and has excellent heat resistance, such as It is constructed from rolled steel such as 5841. Both side surfaces of the heat-resistant plate 1 are cut out in an arc shape so as to match the opening edges of the intake boat and the exhaust boat, and a stepped portion 2 is formed at the lower end as required. Further, this heat-resistant plate 1 is formed with a small hole 3 into which the tip of a fuel injection nozzle is inserted. Further, a pair of leg portions 4 are formed at both ends of the lower surface of the heat-resistant plate 1. Note that the leg portions 4 do not necessarily have to be integral with the heat-resistant plate 1, and may be formed by combining a separate member with the heat-resistant plate 1.

Such a heat-resistant plate 1 is placed on a mounting surface 6 on the side 5 of a sand mold for casting a cylinder head, as shown in FIG. At this time, since the legs 4 of the heat-resistant plate 1 come into contact with the mounting surface 6, a space 7 is formed between the heat-resistant plate 1 and the mounting surface 6.

By pouring molten cast iron into the sand mold in this state, the heat-resistant plate 1 is cast by the cylinder head 8.

Moreover, molten cast iron flows into the space 7 below the heat-resistant plate 1, so that the heat-resistant plate 1 is completely encased in cast iron except for the lower end surface of the leg portion 4. The cylinder head 8, which has been cast by casting the heat-resistant plate 1 in this way, is machined on its lower surface, that is, the surface side facing the combustion chamber, and is thereby removed to the position shown by the chain line 9 in FIG. Become. As a result, the legs 4 of the heat-resistant plate 1 and a portion of the lower surface of the heat-resistant plate 1 are removed at the same time.

FIGS. 3 and 4 show a cylinder head 8 cast in this manner, and an intake boat 10 and an exhaust boat 11 are formed on both sides of the heat-resistant plate 1 of this cylinder head 8, respectively. Valve seats 12, 13 are respectively cast into the opening edges of these intake boats 10 and exhaust boats 11. J3 valve seat 12.1
3 is engaged with a stepped portion 2 formed on the side surface of the heat-resistant plate 1. Further, the intake boat 10 and the exhaust boat 11 have through holes 14 for supporting intake valves and exhaust valves, respectively.
15 are connected. Note that when the lower surface of the cylinder head 8 is removed to the position indicated by the chain line 9, the lower surfaces of the valve seats 12 and 13 are also removed together.

As described above, according to the cylinder head 8 of this embodiment, the leg portions 4 are formed on the heat-resistant plate 1, and the leg portions 4 are placed on the mounting surface 6 of the receiving side 5 of the sand mold as shown in FIG. The heat-resistant plate 1 is held in a floating state as shown, and thereby the heat-resistant plate 1 is cast into the cylinder head 8. Therefore, no special positioning and holding means for holding the heat-resistant plate 1 in a floating state is required.

In addition, since the heat-resistant plate 1 is floated by the legs 4 and placed in a sand mold, melting during pouring occurs at a point 16 where the chain line 9 intersects the heat-resistant plate 1 shown in FIG. The casting material flows sufficiently without locally decreasing in temperature, thereby providing a strong bonding force between the heat-resistant plate 1 and the cylinder head 8. In addition, in this embodiment, with the heat-resistant plate 1 cast into the cylinder head 8, the lower part of the chain line 9 in FIG. Since the heat-resistant plate 1 is machined by cutting, dimensional accuracy such as the installation position and size of the heat-resistant plate 1 is not required so much, which brings about the advantage that the manufacturing cost is also reduced.

As shown in FIGS. 3 and 4, the cylinder head 8 thus obtained has a heat-resistant plate 1 in the portion between the intake boat 10 and the opening of the exhaust port 11, that is, the portion between the pair of valves. Because of this arrangement, it is possible to effectively prevent cracks particularly in the intervalve portion where the heat load is high. Furthermore, this heat-resistant plate 1 has the above-mentioned frontage 10.
．． Since the tip of the chain line 17 connecting the peripheral edge of the cylinder 11 extends outward to a portion where the heat load is low, the cylinder is No thermal cracks will occur in the head 8. Further, in this cylinder head 8, since the heat-resistant plate 1 is directly exposed on the lower surface of the cylinder head 8 between the pair of valves, the heat-resistant effect of the heat-resistant plate 1 can be reliably obtained.

As described above, according to the present invention, legs are formed on the heat-resistant plate cast between the valves of the cylinder head, and the cylinder head is formed with the legs forming a space below the heat-resistant plate. Since the molten metal is injected into the mold, the holding and positioning of the heat-resistant plate is ensured. In addition, heat-resistant plates are cast in a floating state by the legs,
Since the legs are removed after this, the molten metal that makes up the cylinder head flows to the edge of the heat-resistant plate after the removal process without a drop in temperature. The bonding state becomes extremely good. Furthermore, according to the present invention, since the surface of the cylinder head facing the combustion chamber and the cast heat-resistant plate are removed together, the dimensional accuracy of the heat-resistant plate does not need to be low, which reduces costs. This makes it possible to reduce the

[Brief explanation of drawings]

FIG. 1 is a perspective view of a heat-resistant plate cast into a cylinder head according to the method of an embodiment of the present invention; FIG. 3
The figure shows a bottom view of the cylinder head obtained in this way.
FIG. 4 is a sectional view taken along the line IV-IV in FIG. 3. In addition, in the reference numerals used in Drawing 1, 1... Heat-resistant plate 4... Leg portion 8... Cylinder head. Applicant Hino Motors Co., Ltd. Figure 1 Figure 2 Figure 3 Figure 11 21213 Procedure ``L Format (Method) % Formula %] 1. Indication of the case 1982 Patent Application No. 113389 2. Name of the invention Cylinder Head manufacturing method 3. Relationship with the case of the person making the amendment Patent applicant 3-1-1 Hinodai, Hino-shi, Tokyo September 28, 1980 (Shipping port) 5. Specification subject to amendment 6. Amendment Content

Claims (1)

[Claims] In a method of manufacturing a cylinder head in which a heat-resistant plate for preventing cracks between valves is cast and attached, a leg portion is formed on the heat-resistant plate, and the leg portion creates a space on the combustion chamber side of the cylinder head of the heat-resistant plate. molten metal forming the cylinder head is formed into this space, and after casting, at least the metal that has entered the space and the leg are removed, so that the heat-resistant plate faces the combustion chamber. A method for manufacturing a cylinder head, characterized in that the cylinder head is exposed on the surface.