JPS6254985B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a cylinder head for an internal combustion engine having multiple cylinders.

[Conventional technology]

Regarding the temperature distribution of the cylinder head, the exhaust hole and spark plug are generally higher in temperature than other parts. In particular, when the exhaust holes of a plurality of adjacent cylinders are grouped together inside the cylinder head, the exhaust hole portion becomes even hotter, and when the cylinder head is made of aluminum or its alloy, the thermal expansion of the material is large. In such an internal combustion engine, when the engine is put into operation from a cold state, the area around the exhaust hole 2 of the cylinder head 1 becomes hotter than the area around the cylinder head 1, as shown in FIG. The distribution can result in temperature differences of more than 150°C for several minutes. In this state, due to thermal expansion around the exhaust hole 2, the tightening bolt 3 around the cylinder head 1, which is in a cold state, is subjected to tensile force and
The cold state shown by the solid line in the figure changes to the state shown by the chain line, and even though the cylinder head 1 and the cylinder block 5 are tightened with the tightening bolt 3 via the gasket 4, the surface pressure of the gasket 4 increases. This has the drawback that the performance of the engine is reduced, which adversely affects its function and causes leakage of exhaust gas, etc. However, an example of prior art that is considered to be helpful in solving this drawback is described in Japanese Utility Model Publication No. 52-30402, which states that two exhaust ports are merged within the cylinder head. In order to prevent the exhaust gas temperature from decreasing, install an exhaust port liner with a bifurcated tip that opens at the combustion chamber wall at the inlet of each exhaust port and gathers at the downstream side of the exhaust port liner. The supporting piece is press-fitted into the large diameter part of the exhaust port, and supports the exhaust port so that the gap between the gathering part and the inner wall of the exhaust port becomes large.

[Problems to be solved by the invention]

However, according to the above prior art example, the exhaust port liner having a bifurcated tip is supported within the merging exhaust port with a gap between it and the inner wall of the exhaust port to prevent the exhaust gas temperature from decreasing. Although deformation of the cylinder head due to thermal expansion is suppressed as much as possible, there is a problem in that the structure is complicated and uneconomical due to the provision of an exhaust port liner.

[Means to solve the problem]

The present invention has been made in view of the above-mentioned circumstances, and in a cylinder head of an internal combustion engine in which the exhaust holes of a plurality of adjacent cylinders are gathered together inside the cylinder head, the area surrounding the gathering part of the exhaust holes is Along the axial direction of the collecting part from the upstream to the downstream opening end of the collecting part, parallel to the mating surface of the cylinder head to the cylinder block, which is joined by the tightening bolt via the gasket, and of the collecting part. The present invention is characterized in that slits are formed symmetrically on both sides of a plane that includes the axis and is orthogonal to a plane where the cylinder head is fitted to the cylinder block, and that communicates with the gathering portion.

【Example】

Hereinafter, one embodiment of the present invention will be specifically described with reference to the drawings. In FIGS. 2 and 3, the cylinder head 6
is made of aluminum or its alloy material, and the combustion chambers 7 and exhaust valves 8 of the two adjacent cylinders A and A are
The branch portions 9a, which communicate with each other through the cylinder head 6, are provided with exhaust holes 9 that are gathered together inside the cylinder head 6, and the gathering portion 9b of the exhaust holes 9 is open to the outer surface of the cylinder head 6 at the downstream end. Further, the cylinder head 6 is tightened to the cylinder block 5 by a tightening bolt 3 via a gasket 4. A cylinder is provided around the collecting part 9b of the exhaust hole 9 along the axial direction of the collecting part from the upstream to the downstream opening end of the collecting part 9b, and is joined by a tightening bolt 3 via a gasket 4. A surface that is parallel to the mating surface 6a of the head 6 to the cylinder block 5, includes the axis of the collecting portion, and is perpendicular to the mating surface of the cylinder head to the cylinder block, is symmetrical on both sides and communicates with the collecting portion. A slit 10 is formed in the cylinder head 6, and the slit 10 is connected to the collecting portion 9 of the cylinder head 6.
It is formed to have a width and length that absorbs the difference in thermal expansion between the peripheral portion of b and the portion away from it. In addition, in the figure, reference numeral 11 is a suction valve, 12 is a suction hole,
13 is a push rod hole. When the cylinder head configured as described above is put into operation from a cold state, it is heated by the high temperature exhaust gas that is alternately discharged from the surrounding area of the exhaust hole 9, especially from the exhaust holes 9, 9, and reaches a high temperature. Even if the surrounding portions of the collecting portion 9b are heated to a higher temperature than the surrounding portions of the cylinder head 6 that are further away from the collecting portion 9b, deformation due to thermal expansion of these portions will cause the surrounding portions of the collecting portion 9b of the cylinder head 6 to The third part
As shown in the figure, since it can be absorbed by the slit 10, the tensile force generated on the tightening bolt 3 that is distant from the gathering portion 9b is reduced, and therefore the surface pressure distribution of the gasket 4 can be maintained almost uniformly. Therefore, the sealing function of the gasket 4 is improved.

【Effect of the invention】

As explained above, the cylinder head of the internal combustion engine according to the present invention has a gasket around the collecting part of the exhaust holes along the axial direction of the collecting part from the upstream to the downstream opening end of the collecting part. Symmetrical on both sides with respect to a plane that is parallel to the mating surface of the cylinder head to the cylinder block and that includes the axis of the gathering part and is orthogonal to the mating surface of the cylinder head and the cylinder block, which are joined by tightening bolts through the cylinder block. Since we formed a slit that communicates with the collecting part at the target, the difference in thermal expansion between the surrounding part of the collecting part and the part away from it due to exhaust heat can be
This can be absorbed by the deformation of the slit section provided in the surrounding area, thereby making the surface pressure distribution of the gasket uniform and improving its sealing function, thereby reducing exhaust gas from the tightening section between the cylinder head and cylinder block. leakage can be prevented. Therefore, the present invention provides a gap in the combined exhaust port of the cylinder head in order to prevent the temperature of the exhaust gas from decreasing as in the prior art example and to prevent the surrounding area of the combined exhaust port of the cylinder head from being heated by the exhaust heat. Since the structure is simpler than that in which an exhaust port liner is installed for heat insulation, it has the effect of reducing the cost of forming the cylinder head.

[Brief explanation of the drawing]

Fig. 1 is a schematic side view for explaining the operation of a conventional cylinder head, Fig. 2 is a partially cutaway bottom view of a cylinder head showing an embodiment of the present invention, and Fig. 3 is an illustration of Fig. 2. FIG. 3 is a schematic side view of the cylinder head seen from the direction; 1... Cylinder head, 2... Exhaust hole, 3...
Tightening bolt, 4...Gasket, 5...Cylinder block, 6...Cylinder head, 7...Combustion chamber, 8...Exhaust valve, 9...Exhaust hole, 9a...Branch part, 9b...Collection part , 10...slit, 11...
...Suction valve, 12...Suction hole, 13...Push rod hole, A...Cylinder.

Claims (1)

[Claims] 1. In a cylinder head of an internal combustion engine in which the exhaust holes of a plurality of adjacent cylinders are gathered together inside the cylinder head, the axis of the gathering part extends from the upstream of the gathering part to the downstream opening end of the gathering part in the peripheral part of the gathering part of the exhaust holes. along the direction, parallel to the mating surface of the cylinder head to the cylinder block which is joined by the tightening bolt through the gasket, and including the axis of the gathering part and the mating surface of the cylinder head to the cylinder block. A cylinder head for an internal combustion engine, characterized in that slits are formed symmetrically on both sides of orthogonal planes and communicate with the gathering portion.