JPS59231164A - Cylinder head and manufacture thereof - Google Patents

Abstract

PURPOSE:To restrain deformation of suction valve seat by a method wherein a reinforcing ring is fitted forcibly into a hole for an ignition plug to resist against the inflating tendency of the suction valve seat toward the side of the ignition plug by utilizing outwardly expanding internal stress generated in the ring. CONSTITUTION:The reinforcing ring 10, made of a highly rigid material such as cast iron, cast steel or the like, is forcibly fitted into the hole 8 for the ignition plug 8 at the side of a combustion chamber so as to exist the sufficient expanding internal stress by providing it with a proper interference. In case the reinforcing ring 10 is inserted into the hole for the ingition plug, the holes for inserting suction and exhaust valve seats and the hole for inserting the reinforcing ring 10 are machined at the same time or sequentially, thereafter, the suction and exhaust valve seats 14, 16 and the reinforcing ring 10 are inserted simultaneously or sequentially by means of cold-fitting, shrink-fitting or the like to effect force-fitting.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to an improvement in a cylinder head for an internal combustion engine and a method for manufacturing the same. The present invention relates to a cylinder head that prevents deformation and a method of manufacturing the same.

[Technical Background of the Invention] (1) The cylinder head of an internal combustion engine has an intake hole, an exhaust hole, a spark plug hole, etc., and also has an intake/exhaust valve, a spark plug, a valve mechanism, a cooling section, etc. The cylinder head structure has a very complex shape and structure, and while the inside of the cylinder becomes extremely hot during engine operation, the cooling section cools this down, so the temperature gradient inside the cylinder head structure is large and the temperature distribution is complicated.

In particular, since aluminum has a high coefficient of thermal expansion, aluminum cylinder heads are prone to large internal stress and deformation due to heat during operation, so consideration must be given to structural strength and mitigation of thermal gradients. There is.

[Problems with the background art] However, the intake valve seat is a structurally weak part due to its large opening, and while the part near the outer periphery is cooled by the intake air and is relatively low temperature, the part near the center of the cylinder is high temperature. Particularly in the case of a four-valve cylinder head, the intake valve seat portion near the center of the cylinder bulges and deforms in the direction of the spark plug hole in the center due to thermal expansion. As a result, a gap is created between the intake valve and the valve seat (2), causing gas leakage and deteriorating engine performance.

In conventional cylinder heads, the valve seat material is press-fitted into the aluminum base material around the intake and exhaust holes, and it has been difficult to prevent the deformation.

Furthermore, Japanese Utility Model Publication No. 48-25923 proposes a cast iron cylinder head in which dissimilar metals are cast for reinforcement in parts that require particularly high strength, such as around the intake and exhaust ports. Although it is difficult to manufacture and expensive, it is not sufficient to solve the above problems.

[Object of the Invention] Therefore, the object of the present invention is to press-fit a reinforcing ring into the spark plug hole, and utilize the expandability, that is, the internal stress that tends to expand outward, generated inside the reinforcing ring. The purpose is to suppress the deformation of the intake valve seat by counteracting the tendency of the intake valve seat to bulge toward the spark plug side.

[Structure of the Invention] To achieve this object, the present invention provides a cylinder head for an internal combustion engine and a method for manufacturing the same, in which a reinforcing ring is tightly fitted into the ignition hole, and an expandable reinforcing ring is fitted into the reinforcing ring. It is characterized by preventing thermal deformation of the intake valve seat by incorporating internal stress.

[Embodiments of the Invention] Examples of the present invention will be specifically described below based on the drawings.

The figure shows two intake holes 4 and two exhaust holes 6 (11i1).
A pulp cylinder head 2 is shown.

1 and 2 are plan views of the cylinder head viewed from the cylinder side, and FIG. 3 is a sectional view taken along the line 1--2 in FIG. 2.

As described above, as the internal combustion engine operates, the inside of the cylinder becomes high temperature due to the high temperature combustion gas, and in particular, the cylinder head becomes extremely high temperature as it comes into direct contact with the high temperature gas during combustion. However, since the intake hole portion is cooled by intake air, the portion near the outside of the cylinder head, that is, the outer portion 4a
is relatively low temperature, but the inner part (4) 4b, which is the part near the center of the cylinder, is high temperature because it is close to the combustion center and no heat is dissipated. Therefore, the area around the intake hole cannot be uniformly thermally deformed (expanded), and the inner part 4b of the intake hole, which is heated to a high temperature and tries to stretch, is prevented from stretching, so it bulges and deforms as shown by the dotted line. That will happen.

This tendency is noticeable in the case of aluminum cylinder heads because of their large coefficient of thermal expansion.

The valve seat 14 is fitted into the suction/JJI hole, but the valve seat 1
4t) Both bulge and deform, resulting in poor contact with the valve, creating a gap, causing gas leakage, and lowering the compression ratio.
This will cause adverse effects such as unstable idling and reduced output.

Therefore, as a means for preventing deformation of the intake hole according to the present invention,
A reinforcing ring 10 made of a highly rigid material such as cast iron or cast steel is press-fitted into the combustion chamber side of the ignition plug hole 8, and an appropriate tightening margin is provided to prevent the ring from expanding. Make sure there is enough stress. The extensible internal stress inherent in this reinforcing ring 10 is used to counter the bulging deformation of the inner part 4b of the intake hole and prevent the deformation.
5) This aims to obtain the above-mentioned effects.

The normal manufacturing process for inserting the reinforcing ring 1o according to the present invention into the spark plug opening is to cut the hole for inserting the intake/exhaust valve seat and the hole for inserting the reinforcing ring 1o at the same time or sequentially, and then - It is a process of simultaneously or sequentially inserting and tightly fitting the exhaust valve seat 14, 16 and the reinforcing ring 10 by means such as cold shrinking, shrink fitting, or a combination thereof,
The cost increase is not large.

As a manufacturing process for further fully demonstrating the function and effect of the reinforcing ring 1o according to the present invention, first, the fitting portion of the valve seat 14.16 of the intake/exhaust hole is cut, and the valve seat 14.1 is
6 is tightly fitted by the means described above. Thereafter, the insertion part of the reinforcing ring 10 in the spark plug hole is cut, and the reinforcing ring 1o is tightly fitted by the above-described means. According to this process order, it is possible to more reliably incorporate the desired internal stress into the reinforcing ring than in the above-mentioned normal manufacturing process, and to more reliably exhibit the effects of the reinforcing ring according to the present invention.

(6) If the reinforcing ring 10 is tight-fitted, the outer diameter of the reinforcing ring 10 and the inner diameter of the hole should be cut so that there is a sufficient tightness, and after inserting the reinforcing ring 10, The LJ must be processed and attached so that the internal stress that tends to expand in the ring 10 is appropriately and sufficiently contained therein.

Although the above embodiments have been described with respect to a four-valve cylinder head, the technical idea of the present invention is unrelated to the number of valves. Moreover, it goes without saying that if similar measures are taken, it is also effective in preventing thermal deformation of the exhaust hole 6. Furthermore, the reinforcing ring 10 is press-fitted not only in the spark plug hole, but also in places such as the fuel injection valve hole of a diesel engine, as long as the relative positions are the same, of course the same effect can be obtained. .

[Effects of the Invention] As explained in detail above, according to the present invention, thermal deformation of the intake hole of the cylinder head is prevented during operation of an internal combustion engine, thereby preventing gas leakage due to the generation of a gap near the valve seat. This prevents deformation, maintains the compression ratio normally, stabilizes idling operation, prevents low output (7), and improves engine performance.Furthermore, by preventing deformation, it prevents cracks from forming in the core. This can also be prevented, and the effect of extending the life of the engine can be expected.

[Brief explanation of the drawing]

1 and 2 are views of the cylinder head viewed from the cylinder side, FIG. 1 is a plan view of a conventional cylinder head, and FIG. 2 is a plan view of a cylinder head provided with a reinforcing ring according to the present invention. FIG. 3 is a sectional view taken along line mm in FIG. 2. In the figure, 4 is an intake hole, 6 is an exhaust hole, 8 is a spark plug hole,
10 is a reinforcing ring, 14 is an intake valve seat, and 16 is an exhaust valve seat. Agent Patent Attorney Yoshimi Saigo (8)

Claims (1)

[Scope of Claims] 1. A cylinder head for an internal combustion engine, characterized in that a reinforcing ring is tightly fitted into a spark plug hole, and the reinforcing ring has internal expandable internal stress. 2. After tightly fitting the valve seat into the intake/exhaust hole, cut a hole for inserting the reinforcing ring into the ignition plug hole, tightly fit the reinforcing ring into the hole, and apply expandable internal stress to the reinforcing ring. A method of manufacturing a cylinder head for an internal combustion engine, characterized in that a cylinder head is incorporated therein.