JPS6332358Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cylinder head with improved strength and reduced weight.

FIG. 1 is a schematic vertical cross-sectional view of a conventional diesel engine. As shown in FIG. 1, a cylinder head 1 has an annular portion 2 on the bottom wall seated on the upper end surface of a cylinder block 3 via a head packing (not shown). In this state, it is fastened to the cylinder block 3 by, for example, six head bolts 5. However, the head bolt 5 is located on the radially outer side of the cylindrical cylinder head outer circumferential wall 6, whereas the annular portion 2 supported by the cylinder block 3 is located on the radially inner side of the outer circumferential wall 6. Therefore, in the conventional product, there is a gap in the cylinder radial direction (the first If a large distance difference occurs in the left-right direction (in the left-right direction in the figure), and therefore high pressure is applied to the cylinder head 1 from the combustion chamber 7, or if thermal deformation occurs in the cylinder head 1, the area between the annular portion 2 and the outer circumferential wall 6 A large moment is applied to the portion 9, and there is a risk that the portion 9 may crack. In addition, in conventional products, in order to prevent the above-mentioned cracks, the outer peripheral wall 6
As a result, the cylinder head 1 is heavy.

In order to solve the above-mentioned conventional problems, the present invention improves the shape of the outer peripheral wall of the cylinder head and the boss for the head bolt, and is constructed as follows.

That is, in the present invention, the outer circumferential wall of the cylinder head is formed into a cone shape whose diameter becomes smaller toward the cylinder block, and the seating portion that seats on the cylinder block is formed at the tip of the outer circumferential wall. bosses for head bolt insertion are integrally formed at a plurality of locations spaced apart from each other in a state that projects outward in the radial direction of the outer circumferential wall, and bolt insertion holes are formed in the bosses on the radially outer side of the seating portion; The cylinder head is fixed to the cylinder block by a head bolt parallel to the cylinder center line inserted into the bolt insertion hole, and the outer peripheral surface of the boss is inclined so as to approach the cylinder center line as it goes toward the cylinder block side. There is.

Next, embodiments will be described with reference to the drawings.

Figure 2 shows a cylinder head 1 according to an embodiment of the present invention.
0, 11 is an air supply port, 12 is an exhaust port, and 13 is a fuel injection valve mounting hole. The cylinder head outer circumferential wall 15 has a generally annular cross section, and a boss 16 for inserting a head bolt is formed integrally with the outer circumferential wall 15 in a shape that projects radially outward from the outer circumferential wall 15. A total of six bosses 16 are provided at intervals in the circumferential direction of the outer peripheral wall 15, and each boss 16 has a circular cross section.

In FIG. 3, which is a schematic cross-sectional view of FIG. ing. A head packing 19 is interposed between the upper end surface of the cylinder block 20 and the outer peripheral portion 23 of the bottom wall of the cylinder head 10. As is clear from FIG. 3, the outer circumferential wall 15' of the cylinder head 10' before the head bolt is tightened is formed into a cone shape that becomes smaller in diameter toward the cylinder block 20, and even after the head bolt is tightened, the outer peripheral wall 15' of the cylinder head 10' The wall 15 bulges smoothly outward in the radial direction by a very small amount at the middle part in the vertical direction (in a direction parallel to the cylinder centerline O-O), and has a cone shape that is almost the same as before the head bolt is tightened. There is. The outer peripheral wall 15' has a substantially uniform thickness t (for example, 16 mm) over the entire area, and is thinner than the conventional product.

As shown in FIG. 4, which is a schematic cross-sectional view of FIG. The outer circumferential surface 22 of the boss 16 is inclined so as to approach the cylinder center line OO as it goes toward the cylinder block 20 side, and the center line T of the outer circumferential surface 22 is at a distance l (for example, 5 mm) on the side of the head packing 19. The cylinder center line is deviated toward the cylinder center line OO side.

According to the structure of the present invention described above, since the cylinder head outer circumferential wall 15 is formed into a cone shape as shown in FIG.
The direction of the clamping load applied to the cylinder head 5 is inclined along the outer circumferential wall 15, so that the clamping load is applied to the cylinder head 1.
The cylinder block 20 acts toward the head packing mounting portion 23 of the head packing 1.
There is almost no difference in distance between the supporting force applied to the cylinder head portion 23 via the cylinder head 9 and the tightening load. Therefore, no large local moment is applied to the cylinder head 10, and there is no risk that the cylinder head 10 will crack.

Also, conventionally, as shown in FIG.
However, in the present invention, since the outer peripheral wall 15 is cone-shaped, the lower end of the outer peripheral wall 15 forms the part 23 (seating part), and there is no bent part between them. Not formed. Therefore, in the present invention, cracks do not occur near the lower end of the outer peripheral wall 15 unlike in the conventional case.

As shown by the broken line in FIG. 5, the cylinder head 10'' is greatly deformed by the pressure from the combustion chamber, but as described above, the outer circumferential wall 15' remains cone-shaped (without the bend) at the portion 23. Since the slope is continuous with the slope wall 15'', local stress concentration will not occur in the inclined wall 15'' during deformation due to an explosion, and there is no risk of cracking.

Furthermore, according to the present invention, as shown in FIG.
Since it is inclined toward the cylinder center line O-O side as it goes to the side, the tightening load applied from the head bolt 17 to the boss 16 also acts in a direction inclined in a direction close to the direction of inclination of the outer circumferential surface 22. Therefore, the tightening load on the boss 16 is also applied toward the head packing attachment portion 23, and a large local moment is not applied to the boss 16, thereby preventing damage to the boss 16 and its vicinity.

Also, the head bolt 17 is aligned with the cylinder center line O-O.
Therefore, the threaded hole formed in the cylinder block 20 for screwing the head bolt does not need to be inclined with respect to the cylinder center line O--O, and therefore, the processing of the threaded hole is easy.

In this way, in the present invention, the cylinder head outer peripheral wall 1
5 and the outer circumferential wall of the head bolt boss 16 are inclined to increase the strength of the entire cylinder head 10, so the outer circumferential wall 15, etc. can be made thinner than conventional products, and the weight of the cylinder block 10 can be reduced. I can do it.

[Brief explanation of the drawing]

Fig. 1 is a schematic vertical cross-sectional view of a conventional diesel engine, Fig. 2 is a cross-sectional view of a cylinder head according to the present invention, Figs. 3 and 4 are schematic cross-sectional views of - and -, respectively, of Fig. 2, and Fig. The figure is a partial cross-sectional view corresponding to FIG. 3 for showing the deformed state at the time of explosion. 10...Cylinder head, 15...Outer peripheral wall, 1
6...Boss, 17...Head bolt, 20...Cylinder block, 22...Boss outer circumferential surface, O-O...
...Cylinder center line.

Claims (1)

[Scope of utility model registration request] The outer circumferential wall of the cylinder head is formed into a cone shape whose diameter becomes smaller toward the cylinder block, and a seating portion for seating on the cylinder block is formed at the tip of the outer circumferential wall, spaced apart in the circumferential direction of the outer circumferential wall. Bosses for head bolt insertion are integrally formed at a plurality of locations in a state that projects outward in the radial direction of the outer circumferential wall, bolt insertion holes are formed in the bosses on the radial outside of the seating portion, and bolt insertion holes are formed in the bosses in the radial direction outside the seating portion. A cylinder head characterized in that the cylinder head is fixed to a cylinder block by a head bolt parallel to the cylinder center line inserted through the cylinder head, and the outer circumferential surface of the boss is inclined so as to approach the cylinder center line as it goes toward the cylinder block side.