JPS6224023Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to the cylinder head of an internal combustion engine, which is mounted on the crankcase and has intake and exhaust ports together with the combustion chamber. This invention relates to something that prevents the harmful effects of thermal expansion caused by exhaust gas.

[Prior Art] Conventionally, the engine body of an internal combustion engine has a crankcase 1 and a gasket 2, as shown in FIG.
A head body 4 of the cylinder head 3 is placed through the combustion chamber 5, and a combustion chamber 5 and an exhaust port 6 communicating therewith are formed in the head body 4, and an exhaust valve 7 is formed in the head body 4.
are provided to open and close the exhaust port 6. Also,
The intake port 8 is formed in the same manner, and a cooling water passage 9 is provided especially around the combustion chamber 5 and the exhaust port 6.

In addition, in Utility Model Application No. 50-53517, a plurality of cavities are provided near the exhaust port so as to surround the port to prevent the heat of the exhaust gas from being transferred to the water cooling jacket side. It is described that the exhaust gas is maintained at a high temperature, thereby promoting the oxidation reaction in the reactor and reducing harmful components in the exhaust gas. In addition, regarding the provision of a slit-shaped insulation zone in the cylinder head,
Although there is prior art related to Publication No. 24165,
This structure differs from the present invention in that it is formed perpendicular to the gasket mounting surface to partition adjacent combustion chambers.

[Problems to be solved by the invention] By the way, in the head body 4 of such a cylinder head 3, the area around the exhaust port 6 is always heated by high-temperature exhaust gas, and there is no difference between it and a point far away from the exhaust port 6. A uniform temperature distribution occurs, and as shown in FIG. 2, the gasket mounting surface 4b of the low-temperature section 4a, which is far away from the exhaust port 6, becomes slightly floating, as shown by the broken line, due to large thermal expansion at the exhaust port 6. There is a problem in that the surface pressure there decreases, causing water and oil leaks.

[Means for Solving the Problems] The present invention has been made to eliminate such problems, and the thermal deformation in the direction perpendicular to the gasket mounting surface causes the low-temperature part to warp around the exhaust port. In order to prevent surface pressure from decreasing, an insulating zone consisting of a slit with a rectangular or arcuate cross-section with the side substantially parallel to the gasket mounting surface being longer is installed near the exhaust port so as to sandwich the exhaust port. The present invention provides a cylinder head for an internal combustion engine in which thermal expansion of the head body in a direction perpendicular to the passage direction of the exhaust port is absorbed by the insulation zone.

[Function] By having the above-mentioned means, the present invention allows the thermal expansion of the head body in the direction orthogonal to the path direction of the exhaust port to be locally divided into two by the slit, and only the slit portion around the exhaust port is affected. Since the heat expands within the slit and is absorbed by it, thermal deformation of the gasket mounting surface of the head body is prevented, thereby ensuring the surface pressure of the head body and the sealing performance of the gasket, thereby preventing water and oil. It is possible to prevent leaks such as

[Example] Hereinafter, an example of the present invention will be specifically described with reference to the drawings. According to the first embodiment of the present invention shown in FIGS. 3 and 4, in the head body 4 of the cylinder head 3 constructed in the same manner as in FIG. Obi 1
The insulation zone 10 has two rectangular slits 11 substantially parallel to the gasket mounting surface 4b formed on both sides of the exhaust port 6 so as to sandwich the exhaust port 6 therebetween. That is, the slit 11 is
A gasket mounting surface 4b is provided near the periphery of the exhaust port 6.
The rectangular shape has a length l of the side substantially parallel to the diameter d of the exhaust port 6 and a width b smaller than the diameter d of the exhaust port 6, and a basic wall thickness of the cooling water passage 9. depth h that separates s t
The portion 4c between the exhaust port 6 and the slit 11 can be easily thermally deformed within the slit 11.

With this configuration, the area around the exhaust port 6 in the head body 4 of the cylinder head 3 is heated by high-temperature exhaust gas and expands equally, but the area around the exhaust port 6 in the head body 4 of the cylinder head 3 is equally thermally expanded. Thermal expansion near the exit of the exhaust port of the head body 4 is locally divided into two by the slit 11, and only the portion 4c around the exhaust port 6 is thermally expanded and absorbed within the slit 11 as shown by the broken line.
Therefore, thermal deformation does not occur on the gasket mounting surface 4b of the head body 4 and the surface 4d on the opposite side thereof, thereby preventing a reduction in surface pressure due to warping of the gasket mounting surface 4b of the low temperature section 4a. be.

Next, according to the second embodiment of the present invention shown in FIGS. 5 and 6, a hole 12 with a larger diameter is bored at the outlet of the exhaust port 6, and a cylinder 13 is inserted into the hole 12.
is fitted. The cylindrical body 13 has a notch 14 formed on its outer circumference at an angle θ of about 120 degrees, and has a notch 14 formed on the gasket mounting surface 4b and the opposite surface 4d, as in the first embodiment described above. A similar rectangular slit 11' is arranged almost parallel to the gasket mounting surface and sandwiching the exhaust port 6, and overlaps with the cooling water passage 9, thereby providing insulation over the entire length of the exhaust port 6. can be expected.

Thus, in this embodiment, the thermal expansion of the head body 4 in the direction perpendicular to the passage direction of the exhaust port 6 is
It is locally divided into two parts by the slit 11', and only the thin portion 13a at the notch 14 of the cylinder 13 is thermally expanded and absorbed within the slit 11' as in the first embodiment.

[Effect of the invention] As described above, according to the invention, the slit 11 or 11' around the exhaust port 6 can
Thermal expansion in the direction perpendicular to the gasket mounting surface 4b is absorbed and no thermal deformation occurs in that direction.Therefore, thermal deformation of the gasket mounting surface of the head body is prevented, and surface pressure on the gasket mounting surface can be ensured. Therefore, the sealing performance of the gasket 2 is improved and water and oil leakage can be prevented, and it becomes unnecessary to increase the number of tightening bolts. Furthermore, if the cooling water passage 9 is extended to the position of the slit 11 or 11', the core sand tends to collapse during casting, but in the case of the first embodiment of the present invention, it can be cast out using the outer peripheral mold. The slit 11 can be formed reliably.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an example of a conventional cylinder head, Fig. 2 is a side view of the same, Fig. 3 is a sectional view showing a first embodiment of the cylinder head according to the present invention, and Fig. 4 is a side view of the same. 5 is a sectional view showing a second embodiment of the cylinder head according to the present invention, and FIG. 6 is a side view of the same. 2...Gasket, 3...Cylinder head, 4
...Head body, 4b...Gasket mounting surface, 1
0...Warm zone, 11,11'...Slit.

Claims (1)

[Scope of utility model registration request] A heat insulating zone consisting of a slit having a rectangular or arcuate cross-section with the side substantially parallel to the gasket mounting surface elongated is provided near the exhaust port of the head body so as to sandwich the exhaust port, and is installed in the direction of the passage of the exhaust port. 1. A cylinder head for an internal combustion engine, characterized in that the thermal expansion near the outlet of the exhaust port of the head body in a direction orthogonal to the cylinder head is absorbed by the insulation zone.