JPS5882045A - Structure of cylinder head for engine - Google Patents

Abstract

PURPOSE:To concentrate the tightening force of head bolts uniformly, by shaping the upper wall of a cylinder head surrounded by the head bolts disposed around the circumference of cylinders, into a spherical structure curved in a concave manner toward combustion chambers in the vicinity of the head bolts. CONSTITUTION:The upper wall 2 of a cylinder head 1 is surrounded by a side wall 3, and boss portions 5 having respectively a bolt hole are formed at positions corresponding to each corner of a rectangle defining each cylinder. The head bolts are extended through respective bolt holes of the boss portions 5 and clamp the cylinder head 1 to the cylinder block. Here, the upper wall 2 is shaped to have a spherical surface 10 curved downward over the entire region thereof for each cylinder, and the boss portions 5 are connected to the spherical surface 10 at the regions where the spherical surface is raised upward. Resultantly, the clamping force of the head bolts is distributed substantially uniformly around the boss portions 5, so that it is acted uniformly around the combustion chambers.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in the structure of an engine cylinder head, and in particular to the support structure of the lower wall of the cylinder head that contacts the cylinder block body via a gasket.

Generally, a cylinder head has an earthen wall and a lower wall, and between the earthen wall and the lower wall, there is a holding wall that holds the valve stems of the intake and exhaust valves, and a port wall or port that forms the intake and exhaust ports. It has a wall structure in which the walls are connected alone, and is fixed to the cylinder block body via a gasket by fastening the earthen walls with a plurality of head bolts.

In this case, the cylinder head is subjected to pressure within the combustion chamber, especially excessive combustion pressure during the explosion stroke, and this pressure causes the lower wall to deform upward by an angle, creating a gap between the cylinder head and the cylinder block. However, there was a problem in that the sealing performance of the gasket interposed between the two deteriorated and the leakage of engine cooling water and combustion gas was induced.

Conventionally, in order to increase the support rigidity for the lower wall, it is known that the earthen wall is curved convexly downward in the width direction of the cylinder head (see Japanese Utility Model Application No. 52-32614).
.

Such an earthen wall structure is certainly effective in increasing the support rigidity of the earthen wall, but when considered in relation to the tightening force of the head bolts installed around the combustion chamber shield, the downward direction of the head bolts Although the tightening force acts on the top wall in the round direction, it does not actually act on the uncurved longitudinal direction because the earth wall and the head bolt are perpendicular to each other. There was a drawback that the force could not be evenly and effectively concentrated on the lower wall portion at the center of the combustion chamber, and upward deformation of the lower wall could not be sufficiently prevented.

The present invention has been made in view of such problems, and includes:
The supporting rigidity of the earthen wall can be further increased, and the tightening force of the head bolt can be evenly concentrated in the combustion chamber part of the lower wall, thus reliably preventing upward deformation of the lower wall. The basic objective is to provide a cylinder head structure that can effectively maintain sealing performance with a gasket. □ Therefore, in the present invention, the earthen wall portion surrounded by a plurality of head bolts, usually four, arranged around the combustion chamber has a spherical shape that is convex downward to the vicinity of the head bolts. It is a basic feature.

With such an upper wall structure, the tightening force of each head bolt is
Through the spherical structure of the earthen wall, it can be applied centripetally and uniformly toward the center of the combustion chamber, and through, for example, a port wall that connects the upper and lower walls near the center of the combustion chamber. The lower wall is pressed and held with a large supporting force, and as a result,
This makes it possible to reliably prevent upward deformation of the lower wall.

Hereinafter, the present invention will be described in more detail based on illustrated embodiments.

In FIG. 1, 1 is a cylinder head, 2 is an earthen wall surrounded by a side wall 3, and 4 to . -..., 4 corresponds to each rectangular corner part that partitions each cylinder, and penetrates into the bolt hole (not shown) of each boss part 5 provided on the upper wall 2 to connect the cylinder head 1 to the cylinder block. A head bolt 6.7 is fixed through a gasket, and 6.7 is a retaining wall for holding the valve shafts of the intake and exhaust valves, which is formed approximately midway between adjacent head bolts 4.4 in the longitudinal direction of the cylinder head 1. 81
. . , 8 is a holding base that is located between each pair of head bolts 4.4 facing each other in the width direction of the cylinder head 1, and forms a shaft hole 9 for a camshaft, as shown in FIG.

The upper wall 2 is formed as a downwardly convex spherical part 10 over almost the entire area of each cylinder, as shown by the hatching in Figure 1. Each pair of holding stands 8 facing each other in the longitudinal direction of
．． 8, and the side walls 31 on both sides are continuous in the width direction of the cylinder head 1, and the above-mentioned holding base 6.7 is continuously formed in the spherical part 10.

As shown in FIG. 3, the spherical portion 10 is attached to the lower wall of the cylinder head 1 which is attached to the cylinder block 14 via a gasket 15 by a port wall 13 defining intake and exhaust ports 11 and 12. As a result, the tightening force of each head bolt 4 is transmitted from the spherical portion 10 continuous to each boss portion 5 to the lower wall 16 via the port wall 13.

This lower wall 16 has an upwardly convex concave portion 18 (corresponding to the cylinder bore of the cylinder 17 of the cylinder block 14).
2), which together with the cylinder 17 form a combustion chamber 19, and which are held in the shaft holes of the retaining wall 6.7 via valve guides 20.21 by opening and closing operations of the intake valves 22 and exhaust valves 23. , intake air is supplied to the combustion chamber 19 from the intake port 11, or exhaust gas is discharged to the outside from the exhaust port 12.

In addition, in FIGS. 2 and 3, 24 and 25 are cooling water passages provided in the cylinder head 1 and cylinder block 14, respectively, and as shown in FIG. Here, they are communicated with each other via a communication hole 26 provided in the gasket 15, so that cooling water is continuously circulated.

When the upper wall 2 is formed as a spherical part 10 as described above, the boss part 5 is continuous with the spherical part 10 at the raised part 1 of the spherical surface, and the head bolt 4 The tightening force is transmitted to the spherical part 101 via the boss part 5. In this case, the tightening force is distributed almost equally around the boss portion 5, or considering the center of the spherical portion 10, the tightening force is uniformly distributed from the boss portions 5 at the four corners to this center. As a result, a large clamping force acts uniformly distributed in the circumferential direction of the combustion chamber 19, and this large clamping force acting on the center area acts on the lower wall 16 via the port wall 13. Therefore, the lower wall 16 is held so as not to be displaced against the high combustion pressure generated in the combustion chamber 19 during explosion and combustion of each cylinder, and the lower wall 16 is held so as not to be displaced against the high combustion pressure generated in the combustion chamber 19 during explosion and combustion of each cylinder. The sealing performance of the gasket 15 can be improved by evenly pressing the gasket 15 around the gasket 15, and leakage of combustion gas and cooling water from the communication port 26 will not occur.

Furthermore, as described above, if the upper wall 2 is configured with a plurality of spherical parts 10, the rigidity of the upper wall 2 is greatly improved in all directions 1, so the upper wall 2 can be made thin. , it is also advantageous as a vibration damping structure.In particular, if the spherical portion 10 is connected to the side wall 3 in one direction of the cylinder head 1, the support rigidity for the side wall 3 can be increased, and the cylinder head 1
The structure can be extremely advantageous for damping the vibration of the rocker cover attached to the upper side of the rocker cover.

Furthermore, the spherical portion 10 can be used as an oil reservoir,
It can be used to lubricate a camshaft (not shown) disposed along the longitudinal direction of the cylinder head 1.

In the above embodiment, the radius of curvature is the same over the entire surface of the spherical part 10, but for example, the radius of curvature may be slightly different in the longitudinal direction and the width direction of the cylinder head 1, so that the spherical part 10 is completely spherical. There's no need.

Further, in the above embodiment, the present invention is applied to the cylinder head 1 in which the upper wall 2 and the lower wall 16 are connected by the port wall 13. Needless to say, the present invention can also be applied to a structure that connects the earthen wall and the lower wall of the cylinder head with port walls forming intake and exhaust ports.

As is clear from the above description, the present invention provides an engine characterized in that the upper wall of the cylinder head is formed into a spherical surface with a single downward convexity extending to the vicinity of the head bolts arranged around the cylinder for each cylinder. This provides a cylinder head structure.

According to the present invention, the tightening force of each head bolt disposed around each cylinder can be uniformly applied to the lower wall around the combustion chamber and the gasket, so that the sealing performance of the gasket can be improved. Not only that, but the rigidity of the earthen wall itself can be increased, so the earthen wall can be made thinner, and the weight can be reduced by 7 dahes, making it advantageous as a vibration damping structure. You can get the advantage of being able to

[Brief explanation of drawings]

FIG. 1 is a partial plan view of a cylinder head according to an embodiment of the present invention, and FIGS. 2 and 3 are lines AA and B in FIG. 1, respectively.
FIG. 4 is a cross-sectional view in the direction of line -B, and is a perspective explanatory view of the main part of the cylinder head, showing a structure for distributing the tightening force of the head bolt. DESCRIPTION OF SYMBOLS 1... Cylinder head, 2... Upper wall, 4... Head bolt, 5... Boss part, 6.7... Retaining wall, 10
... Spherical part, 11.12 ... Suction, exhaust port, 13
...Port wall, 14...Cylinder block, 15.
...Gasket, 16...Lower wall, 19...Combustion chamber. Patent applicant: Toyo Kogyo Co., Ltd. Agent: Patent attorney: Aohaku Ao and two others Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] (1) The upper wall of the cylinder head is connected to the lower wall of the cylinder head that forms the combustion chamber by a holding wall that holds the valve stems of the intake and exhaust valves and a port wall that forms the intake and exhaust ports or the port wall. In the cylinder head structure of the engine, the earthen wall of the cylinder head, which is substantially concave by a plurality of head bolts arranged around the outer periphery of the cylinder, is concave toward the combustion chamber to the vicinity of each of the head bolts. An engine cylinder head structure characterized by a curved spherical structure.