JPH0452409Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to internal combustion engines, and in particular, to an internal combustion engine that is equipped with a direct-acting valve mechanism in which intake and exhaust valves are driven directly via a valve lifter using a dedicated camshaft. This invention relates to cylinder head structures for internal combustion engines.

[Conventional technology and problems]

In general, in internal combustion engines, in order to increase the amount of intake air for the purpose of achieving high speed and high output, a valve mechanism consisting of a plurality of intake valves and exhaust valves per cylinder is known. For example, three intake valves are arranged in an arc shape. A mechanism has been proposed.

Due to the special arrangement of three intake valves, the valve lifters located at the ends of these intake valves have to be installed in close proximity to each other in the cylinder head, and there is no space between the valve lifters of adjacent cylinders and the cylinder head member thickness. The thickness of the cylinder head member between the three valve lifters in one cylinder cannot be made large enough to provide sufficient strength, which tends to result in insufficient strength. Conversely, in order to ensure the strength of the cylinder head, the diameter of the valve lifter itself must be limited, and the cam profile on the camshaft that contacts the valve lifter is limited by design, making it impossible to secure a sufficient amount of valve lift, making it necessary to increase the number of intake valves. Therefore, the purpose of increasing the amount of intake air is not achieved, and this also causes a problem of a decrease in output. In response to this problem, for example, in the specification of Japanese Utility Model Application No. 62-95110, a valve train structure was developed in which the center of the valve lifter and the center of the intake valve were offset to ensure cylinder head strength while increasing the diameter of the valve lifter as much as possible. Although it has been proposed, if the offset amount is made too large, the contact area between the cam and the valve lifter will be concentrated on the periphery of the valve lifter, so the offset amount will naturally be limited and the current situation is that the valve stroke amount will not be improved that much. be.

In view of the current situation, the present invention has been developed to provide a cylinder head that spans the entire cylinder head without sacrificing its strength.
It is an object of the present invention to provide a compact cylinder head structure for an internal combustion engine by arranging valve lifters as large as possible over all cylinders.

[Means for solving problems]

According to the present invention, three intake valves per cylinder are arranged in an arc shape when viewed from above the cylinder head,
In an internal combustion engine having a camshaft that drives the intake valve via a valve lifter connected to the valve end, and another camshaft that drives the exhaust valve, among the three intake valves constituting the one cylinder,
The two intake valves located at both ends are arranged so as to be inclined in the camshaft axial direction and in a direction perpendicular to the camshaft axial direction so that their respective axes move away from the bore axis as they approach the camshaft, and It has a valve operating mechanism in which a valve lifter that engages two intake valves is inclined with respect to the valve axis so that its axis is perpendicular to the camshaft axis, and the distance between the valve lifters is substantially reduced over all cylinders of the engine. A structure of an internal combustion engine is provided, characterized in that the structure of the internal combustion engine is equal to .

[Effect]

Taking advantage of the fact that the distance between the valve lifters increases by arranging the intake valves with respect to the bore axis, slanting both in the direction perpendicular to the camshaft axis and in the direction of the camshaft axis, the cylinder head can be built with the necessary wall thickness for strength. By arranging the intake valve lifters of two cylinders at a distance, the cylinder head part between the valve lifters of adjacent cylinders, which conventionally used to be a dead space, can be effectively used, and a compact cylinder head can be provided.

〔Example〕

Before explaining the cylinder head structure according to the present invention, the valve arrangement of the valve train that makes it possible to provide the cylinder head structure will be explained with reference to the drawings.

FIG. 1 is a bottom view of the cylinder of the cylinder head 10 of the present invention, showing the positional relationship of the intake and exhaust ports.

In this diagram, 1, 2, 3 are intake ports, 4, 5
6 indicates an exhaust port, 6 indicates a spark plug hole, and 7 indicates a combustion chamber. In addition, the dashed-dotted lines 8a and 9a in the figure indicate the respective camshafts 8 and 9 for driving the intake and exhaust valves (Fig. 2).
The axis of the figure is shown, and intake/exhaust valves and valve lifters are omitted.

Figures 2 and 3 are the - and - lines in Figure 1.
FIG. 3 is a sectional view of the cylinder head 10 along a line;
That is, FIG. 2 is a cross section of the intake port 2 located at the center of the three intake ports 1, 2, and 3, and shows the arrangement structure of the intake valve 12 that opens and closes the port 2 and the valve lifter 22. ing.

In the viewing direction shown in FIG. 1, the center of the intake port 2 is the axis 8 of the intake valve driving camshaft 8.
Therefore, the intake valve 12 is arranged approximately parallel to the bore axis A in FIG.
It is arranged coaxially with respect to a. According to the present invention, the valve axis 12a is positioned so that the center of the camshaft 8 is located on its extension, and this positional relationship is the same for other intake valves and exhaust valves to be described later.

FIG. 3 shows the intake valve 11 surrounding the above-mentioned intake valve 12, one exhaust valve 14 corresponding to the intake port 1, one exhaust valve 14 corresponding to the exhaust port 4, and valve lifters 21 and 24 that engage with the respective stem parts. FIG. 3 is a cross-sectional view showing the arrangement structure.

That is, according to this figure, as is clear from the positional relationship between the camshaft axes 8a and 9a and the respective ports 1 and 4 shown in FIG. The distance from the bore axis A increases as the distance from the bore axis A increases as the distance from the bore axis A increases. In other words, the intake valve 11 and the exhaust valve 14 are inclined in a direction perpendicular to the camshaft axis indicated by arrow B. Further, valve lifters 21 and 2 provided at the ends of each valve 11 and 14
4 is arranged coaxially with the valve axes 11a and 14a when viewed in the direction shown in FIG. 3, that is, in the camshaft axis direction.

The arrangement of the intake valve 11 (including the valve lid 21) and the exhaust valve 14 (including the valve lifter 24) described above in the cylinder head 10 is based on the intake port 3 (first port 3) hidden behind the figure.
Figure) Intake valve that opens and closes, and exhaust port 5
The same applies to the exhaust valve that opens and closes (FIG. 1).

FIG. 4 is a schematic view of the valve mechanism seen from the direction of the arrow in FIG. 1, in which the camshaft and intake and exhaust valves are shown along their respective axes.

According to the present invention, three intake valves 11, 1
The two intake valves 11 and 13 located at both ends of the intake valves 11 and 13 move closer to the bore axis A, that is, the intake valve in this figure, as their axes 11a and 13a approach the camshaft 8 (or the camshaft axis 8a). The axis 12a of the valve 12 is arranged to be inclined in the direction of the camshaft axis 8a so as to be further away from each other. In addition, the valve lifters 21 and 23 that engage the intake valves 11 and 13, when viewed from this direction,
The valve lifter axes 21a and 23a are disposed not coaxially with the intake valve axes 11a and 13a, but parallel to the bore axis A, specifically, so that the valve lifter axes 21a and 23a are perpendicular to the camshaft axis 8a, respectively.
Therefore, the intake valve axes 11a and 13a and the valve lifter axes 21a and 23a do not coincide when viewed from this direction, but are arranged at an angle. this is,
Intake valves 11a, 13a and valve lifter 2
Expected when 1 and 23 are arranged coaxially,
In addition to preventing point contact between the cam (not shown) on the camshaft 8 and the top surfaces of the valve lifters 21 and 23 and the resulting uneven wear, the distance between the adjacent valve lifter 22 is kept constant over the entire length of the lifter. By doing so, the intention is to reduce restrictions on the design of the cylinder head intervening in this part, to set the cylinder head wall thickness to a value required for strength, and to make the diameter of the valve lifter 22 as large as possible.

(If they are arranged coaxially, the distance between adjacent lifters will be the smallest at the bottom of the lifter and the largest at the top of the lifter. In designing the cylinder head, emphasis must be placed on ensuring the wall thickness on the former, and the distance between adjacent lifters is the same. In the case of cylinder head length, the lifter diameter has to be made smaller.) In other words, the intake valves 11 and 13 are connected to the camshaft axis direction from the intake ports 1 and 3 at both ends.
Furthermore, by extending radially in a direction perpendicular to the camshaft axis direction, the limited overall length of the cylinder block can be used effectively. Fifth
The figure is a top view of a cylinder head in which the above-described valve train is applied to an in-line four-cylinder internal combustion engine.
According to the present invention, all the intake valve lifters 21, 22, and 23 are arranged at substantially equal intervals as shown in the figure, with a wall thickness that does not pose a problem in terms of the strength of the cylinder head (Fig. 5a). This makes it possible to ensure strength throughout the cylinder head 10.

This arrangement of valve lifters is achieved for the first time by the above-mentioned valve train, and simply tilting the camshaft in a direction perpendicular to the axis will not ensure the cylinder head wall thickness a between the valve lifters per cylinder. In this case, the valve lifter diameter would have to be smaller than the valve lifter diameter shown in FIG.

〔effect〕

As explained above, according to the present invention, each exhaust valve lifter is arranged at substantially equal intervals by effectively utilizing the cylinder head portion between the valve lifters of adjacent cylinders, which conventionally used to be a dead space. The cylinder head strength is not locally impaired, the overall structure is compact, and the cylinder head rigidity is ensured. Further, the arrangement structure of the valve train adopted in the present invention makes it possible to arrange the valve lifters at equal intervals by changing the inclination angle of which intake valve, regardless of the arc arrangement of the intake ports. It is possible to set a valve lifter with a diameter as large as possible, and therefore it is possible to increase the amount of intake air as the amount of valve lift increases.

[Brief explanation of the drawing]

Figure 1 is a bottom view of a cylinder head showing an example of the arrangement of ports in an internal combustion engine, which is the subject of the present invention;
The figure is a cross-sectional view of the cylinder block along the line in Figure 1; Figure 3 is a cross-sectional view of the cylinder block along the line in Figure 1; Figure 4 is a valve lifter and intake/exhaust valves seen from the direction of the arrow in Figure 1. FIG. 5 is a top view showing the cylinder head structure of the present invention. 10... Cylinder head, 11, 12, 13...
...Intake valve, 14, 15...Exhaust valve, 2
1, 22, 23... Valve lifter, 8, 9... Camshaft, A... Bore axis.

Claims (1)

[Scope of utility model registration request] Three intake valves per cylinder are arranged in an arc shape when viewed from above the cylinder head, and a camshaft drives the intake valves via a valve lifter connected to the end of the valve, and another camshaft drives the exhaust valve. In an internal combustion engine having a camshaft, the two intake valves located at both ends of the three intake valves constituting one cylinder are moved away from the bore axis as their respective axes approach the camshaft. The valve lifter is arranged to be inclined in the axial direction and in a direction perpendicular to the camshaft axis direction, and the valve lifter that engages with the two intake valves is inclined with respect to the valve axis so that its axis is perpendicular to the camshaft axis. 1. A cylinder head structure for an internal combustion engine, comprising a valve operating mechanism and having substantially the same distance between the valve lifters over all cylinders of the engine.