JP3010189B2 - The mating surface shape of the cylinder head and cylinder block of a multi-cylinder engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-cylinder engine, and more particularly to an improvement in the shape of a mating surface between a cylinder head and a cylinder block of a multi-cylinder engine.

[Conventional technology]

A force that expands and contracts the gap between the deck surfaces around the combustion chamber acts on the mating surface of the cylinder head and the cylinder block of the internal combustion mechanism due to the pressure of the combustion gas during combustion. For this reason, conventionally, the sealing performance of the joint surface between the cylinder head and the cylinder block has been improved by bolting via a metal gasket having a bead formed on the mating surface of the cylinder head and the cylinder block. .

[Problems to be solved by the invention]

However, when the cylinder head and the cylinder block are bolted through the metal gasket as described above, a reaction force against the bolt fastening force is generated between the bolt fastening portions, and the cylinder head is warped up between the bolt fastening portions. Is deformed.

In particular, in the case of a multi-cylinder engine, a reaction force that warps a central portion in a cross-sectional direction perpendicular to the cylinder hole arrangement direction acts greatly, and a gap is formed that becomes larger from the bolted portion toward the center of the side surface to be removed.

FIG. 5 (a) to FIG. 5 (d) show the situation.

FIG. 5 (a) is a plan view of the deck surface of the cylinder block, in which the arrangement direction of the cylinder holes P1 to P4 is the X direction, and the direction orthogonal to this direction is the Y direction. And the fifth
FIG. 5B shows the gap amount on the cross section AA and the gap amount on the cross section BB in FIG. 5A corresponding to each other. FIG. 5 (c) shows the gap amount in the cross section CC of FIG. 5 (a), and FIG. 5 (d) shows the gap amount in the cross section DD and cross section EE of FIG. 5 (a). It is.

The cause of such a gap is caused by bending in the cylinder head, and since the shape of the cylinder head itself is a box-shaped structure, it is more perpendicular to the cylinder hole arrangement direction than to the rigidity in the cylinder hole arrangement direction. This is because the rigidity in the cross-sectional direction is inferior, and the reaction force in the cross-sectional direction strongly acts between the bolted portions of the cylinder head. For this reason, the gasket surface pressure at the location is reduced, and the sealing performance of the gasket is reduced.Also, the bead of the metal gasket is caused by the alternating load during combustion, and the sealing effect of the metal gasket is further reduced. The disadvantage that gas leaks occurs.

To solve such a problem, for example, Japanese Patent Application Laid-Open
As described in JP-155376, a sub-plate is laminated on a bead-formed substrate, and the sub-plate is folded back to the non-bead forming side of the substrate edge, and a superposed portion having a larger thickness than other laminated portions is provided. Is formed so that the gap between the cylinder head and the cylinder block around the cylinder hole is filled by the overlapping portion.

However, in such a gasket, a portion or a gap portion having a different surface pressure is generated between a portion where the overlapped portion is formed and another portion, so that the heat conductivity is partially different, causing distortion in the engine, In addition, rust is generated due to the intrusion of moisture from places and gaps where the surface pressure is low, and the gasket surface itself is deformed due to thermal distortion, alternating load, etc., and the gasket surface pressure is reduced and the sealing performance is reduced. There's a problem.

In contrast to the above-described conventional metal gasket having an overlapped portion, the gap created between the mating surfaces around the cylinder hole is compensated for by improving the gasket itself, whereas the present invention provides a bolt fastening unique to a multi-cylinder engine. To provide a mating surface shape of a cylinder head and a cylinder block of a multi-cylinder engine formed so as to eliminate a gap itself that warps a central portion in a cross-sectional direction orthogonal to a cylinder hole arrangement direction generated in a mating surface of a cylinder head at the time of the operation. The purpose is to:

[Means for solving the problem]

In order to achieve the above object, the mating surface shape of the cylinder head and the cylinder block of the multi-cylinder engine of the present invention is such that the mating surface shape of the cylinder head and the cylinder block in the multi-cylinder engine is such that the cylinder head and the cylinder The cross-section of one or both of the blocks, which is orthogonal to the cylinder hole arrangement direction, has a semi-cylindrical shape that smoothly rises toward the center.

[Action]

In the present invention having the above structure, the cylinder head, the cylinder block, or both the cylinder head and the cylinder block have a cross-sectional shape orthogonal to the cylinder hole arrangement direction in a semi-cylindrical shape that smoothly rises along the center.

That is, this Kamaboko shape is measured by measuring the gap width of the warpage that occurs in the cross section orthogonal to the cylinder hole arrangement direction by connecting the cylinder head and the cylinder block having a normal flat deck surface with each other and fastening them with bolts. The corresponding height is raised on the cylinder head, the cylinder block, or both of the cylinder head and the cylinder block, or the rigidity against the combustion gas pressure that opens the mating surface around the cylinder hole is measured in accordance with the above measurement result. It can be formed by adding a height of plus alpha to the cylinder head and raising the corresponding height to the cylinder head, the cylinder block, or both the cylinder head and the cylinder block. In the case where the raised portions are formed on both the cylinder head and the cylinder block, the total surface height of the raised portions may correspond to the gap width of the measured value.

Therefore, for example, the section of the cylinder block deck surface perpendicular to the cylinder hole arrangement direction is made into a semi-cylindrical shape that is smoothly raised according to the center, and when the cylinder head is flush with this, the cylinder along the cylinder block side of this mating surface Although a gap in the direction of the hole arrangement occurs, this gap is adjusted to the amount of warpage when the cylinder head is fastened with bolts. I can do it.

Also, in the case where the above-mentioned raised portion is formed on the cylinder head side to form a semi-cylindrical shape, a gap in the cylinder hole arrangement direction along both sides is generated on the cylinder head side, and when this is tightened with a bolt, the cylinder head is similar to the above case. Warpage occurs, and uniform bonding is achieved over the entire mating surface.

Furthermore, in the case where the raised portions are formed on both the cylinder head and the cylinder block to form a semi-cylindrical shape, a gap is generated in the cylinder hole arrangement direction along both sides on both the cylinder head side and the cylinder block side. Similarly, the cylinder head is warped by bolting, and the entire mating surface is uniformly joined.

Incidentally, as a conventional technique, there is a technique in which a portion between bolt fastening portions on a gasket mating surface of a cylinder head or a cylinder block is raised, but this aims at improving sealing performance between bolt fastening portions at the time of bolt fastening. It was done. On the other hand, the present invention has a cross-sectional shape orthogonal to the cylinder hole arrangement direction, regardless of the bolt fastening portion,
It has a semi-cylindrical shape that is raised smoothly along the center as a whole. With such a configuration, the cylinder head and the cylinder head are warped due to the entirety of the cross section that is particularly caused by the bolt fastening especially in the cross section orthogonal to the cylinder hole arrangement direction. The gap formed on the gasket mating surface with the cylinder block is eliminated so that the mating surfaces abut uniformly.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 (a) shows a perspective view of a cylinder block according to the present invention. As shown in this drawing, the deck surface 2 of the cylinder block 1 has a central portion smoothly raised by a height h in a cross section orthogonal to the arrangement direction of the cylinder holes 3, that is, the longitudinal direction of the cylinder block 1, as a whole. It is formed in a kamaboko shape.

FIG. 1 (b) is a schematic cross-sectional view showing the shape of the mating surface of the cylinder head according to the present invention. In this cylinder head 4, it is assumed that the cylinder head 4 corresponds to the cylinder block 1 described above. In the center part of the cross section orthogonal to the arrangement direction of the cylinder holes 3, a height h is smoothly raised to form a kamaboko shape.

In order to form the above-mentioned kamaboko shape into, for example, a cylinder block, as shown in FIG. 2 (a), a cylinder head 21 having a normal flat deck surface and a cylinder block 21 are used.
The maximum height h 'of the warp generated at the center of the cross section orthogonal to the arrangement direction of the cylinder holes 24 is measured by tightening the bolts 23 with the specified torque by aligning the surfaces 22 and opening the mating surface around the cylinder holes. The maximum height h of the cross section protuberance 25 of the cylinder block 22 'shown in FIG. 2 (b) can be determined by adding a height of plus alpha that gives the cylinder head 21 a rigidity against the combustion gas pressure. .

Since the warpage of the cylinder head caused by the bolt fastening is not a flat surface but a smooth curved surface, the raised portion 25 also needs to be formed into a smooth curved surface according to the measurement result shown in FIG. 2 (a). is there. This curved surface processing can be performed, for example, by molding by die casting, or by cutting with a milling machine and grinding with a grindstone.

When the cylinder head 21 having a flat surface is brought into surface contact with the cylinder block 22 'having the maximum height h of the raised portion 25 obtained as described above, as shown in FIG. A gap 30 in the cylinder hole arrangement direction is formed on both sides of the cylinder head 21. As shown in FIG. 3B, when the cylinder head 21 is fastened with bolts 23, the gap 30 is corrected by warpage of the cylinder head 21 when the bolt is fastened. Thus, the mating surface between the cylinder head 21 and the cylinder block 22 'can form a uniform joint surface.

This has been described with respect to the deck surface shape of the cylinder block. However, as shown in FIG.
When a raised portion having a maximum height h is formed on the side, a gap 30 in the cylinder hole arrangement direction is formed on both sides of the mating surface on the cylinder head side, but as shown in FIG. When 21 ′ is fastened with bolts 23, the gap 30 is corrected by the warpage of the cylinder head 21 ′,
21 'and the cylinder block 22 are evenly matched.

Further, the joining surfaces of both the cylinder block and the cylinder head may be raised from each other so that the total surface height becomes h. Although not shown in this case, as can be determined from the above two embodiments, a gap in the cylinder hole arrangement direction occurs on both sides of the mating surface between the cylinder head side and the cylinder block side. Similarly, by tightening the cylinder head with bolts, the gap is corrected, and the cylinder head and the cylinder block are evenly aligned.

FIG. 6 shows a situation in which the maximum height h of the raised portion 25 is formed on the deck surface of the cylinder block shown in FIGS. 2 (a) and 2 (b). FIG. 6 (a) is a positional change diagram of the height of the raised surface in the cross section cc showing the plane of the deck surface of the cylinder block shown in FIG. 5 (a). It is 50 μm. When a cylinder head with a flat surface is bolted to this,
As shown in FIG. 6 (b), the cylinder head has only a small gap, and it can be seen that the cylinder head is significantly reduced as compared with the conventional gap amount in the same section cc.

In the present invention, the above-mentioned kamaboko shape is used as a basic shape, and variously changing the surface of the kamaboko shape according to, for example, the tightening condition of the cylinder head, the combustion gas pressure condition in the cylinder hole, etc. It does not hinder, for example, by changing the cylindrical shape of the piston into an elliptical shape, a taper, etc. under various conditions to conform to the cylindrical shape of the cylinder, to improve the basic performance such as followability to the cylinder, oil consumption, etc. As with what is being considered, it should be considered in actual applications.

〔The invention's effect〕

As described above, the mating surface shape of one or both of the cylinder head and the cylinder block is a semi-cylindrical shape in which the cross-sectional shape orthogonal to the cylinder hole arrangement direction is smoothly raised according to the center, so that the cylinder head is formed into a cylinder block. When the bolts are tightened in a face-to-face manner, the warpage of the cylinder head caused by the bolt fastening force is matched to the shape of the facing mating face, and the face-to-face uniformity is achieved.

Accordingly, the metal gasket interposed between the cylinder head and the cylinder block is formed of a single plate in the related art, and a sufficient sealing property can be secured, and the sealing of combustion gas, moisture, oil, etc. can be reliably performed. .

In addition, the effect of equalizing the mating surface between the cylinder head and the cylinder block of the present invention improves the sealing property of the metal gasket, and there is no danger of moisture entering the mating surface. Since there is no unevenness in the performance, distortion of the engine can be prevented.

Furthermore, according to the present invention, there is no need for a metal gasket in which a conventional overlapping portion is formed around a cylinder hole, which is advantageous in terms of cost.

[Brief description of the drawings]

FIG. 1 (a) is a perspective view showing an embodiment of a cylinder block according to the present invention, FIG. 1 (b) is a perspective view showing an embodiment of a cylinder head according to the present invention, and FIGS. b)
FIG. 3 is a schematic sectional view showing a method of forming a raised portion on the deck surface of a cylinder block according to the present invention, FIG.
FIG. 4B is a schematic cross-sectional view showing a situation at the time of bolt fastening when a raised portion is formed on the cylinder block side. FIGS. 4A and 4B are bolts when a raised portion is formed on the cylinder head side. FIG. 5 is a schematic cross-sectional view showing a situation at the time of fastening, FIG. 5 is a view for explaining a gap at the time of bolt fastening by a position of a deck surface in a cylinder block of a conventional multi-cylinder engine, and FIG. FIG. 6 (b) is a diagram showing the height of the raised surface in section cc corresponding to FIG. 6 (a).
FIG. 4 is a diagram for explaining a gap at the time of bolt fastening at the position shown in FIG. 1, 21, 21 '... cylinder head, 22, 22' ... cylinder block, 23 ... bolt, 24 ... cylinder hole, 30 ...
Gap width, h: The maximum height of the ridge in the Kamaboko shape.

Claims (1)

(57) [Claims] In a multi-cylinder engine, in a mating surface shape of a cylinder head and a cylinder block, a sectional shape orthogonal to a cylinder hole arrangement direction of one or both of the cylinder head and the cylinder block becomes smoother as approaching the center. A mating surface shape of a cylinder head and a cylinder block of a multi-cylinder engine, characterized in that the shape is a raised semi-cylindrical shape.