JPH0610092Y2 - Cylinder head valve lifter holding structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a structure of a valve lifter holding portion of a cylinder head in a valve train of an internal combustion engine.

[Prior Art] In a conventional valve train of an internal combustion engine, a valve lifter holding portion formed on a cylinder head is generally structured as shown in, for example, Japanese Utility Model Laid-Open No. 58-108206. That is, the valve lifter holding part whose inner surface is formed on the sliding surface for the valve lifter is supported by the cam journal bearing part and the wall around the valve lifter holding part. Is designed to have a minimum required length.

However, in the above structure, the wall portion that constitutes the valve lifter holding portion is separated from the peripheral wall portion that supports the valve lifter holding portion, and these portions are connected by a wall that hardly contributes to the rigidity of the valve lifter holding portion itself. Because of the structure, when the valve lifter has a large outer diameter and a large force is applied from the valve lifter to the valve lifter holding portion, the rigidity of the valve lifter holding portion becomes a problem. In particular, in the case of a direct drive type valve operating system, a large force is applied to the valve lifter in a shocking manner, and therefore it is desirable that the valve lifter holding portion has sufficient rigidity to withstand it. Further, since the lower portion of the wall portion that constitutes the valve lifter holding portion has a structural shape that is separated upward from the upper wall of the water jacket, there is a risk of casting defects such as shrinkage cavities during cylinder head casting. Further, when the cylinder length of the valve lifter holding portion is short, there is a problem that it becomes difficult to maintain the sliding posture of the valve lifter over the entire valve lifter sliding area.

With respect to such a problem, the following conventional structure is known although it is not intended to solve the above problems.

Japanese Utility Model Laid-Open No. 59-103808 discloses a structure in which the inner surface of the cylinder of the valve lifter holding portion is extended over the entire circumference and the entire length of the valve spring installation length, and no hollow portion is provided around the valve lifter holding portion. There is.

Further, in Japanese Utility Model Laid-Open No. 57-193907, a structure in which a cylindrical wall of a valve lifter holding portion is extended to be connected to a lower wall over substantially the entire circumference, and a hole is provided in a part of the extended wall It is shown.

[Problems to be Solved by the Invention] However, in the structure of Japanese Utility Model Publication No. 59-103808, the rigidity of the valve lifter holding portion and the sufficient sliding length of the valve lifter can be secured, but the inner surface of the valve lifter holding portion is Since it is formed in the shape of a bottomed container, there is a problem that the oil accumulates, and there is no escape hole for the oil, which deteriorates the oil. Further, since there is no hollow portion around the valve lifter holding portion, there is a problem that it is difficult to reduce the weight of the cylinder head and thus the entire engine.

In the structure disclosed in Japanese Utility Model Laid-Open No. 59-193907, the holes allow the oil to escape, but the wall for holding the valve lifter extends downward over substantially the entire circumference. However, there are still problems regarding weight reduction.

The present invention solves the problems in the conventional general structure as described above and the problems in the conventionally proposed technology. Therefore, the present invention is most efficient without significantly impeding the weight reduction of the engine and prevents the oil from escaping. An object of the present invention is to improve the rigidity of the valve lifter holding portion, stabilize the sliding posture of the valve lifter, and improve the hot running property of the valve lifter holding portion during casting without causing the occurrence.

[Means for Solving the Problems] A valve lifter holding structure for a cylinder head according to the present invention for this purpose is formed on a cylinder head and has a cylindrical inner surface, and the cylindrical inner surface is formed on a sliding surface for a valve lifter. In the holding portion, the lower portion of the valve lifter holding portion is partially extended in the circumferential direction so as to be continuous with the upper wall of the water jacket at a position where the diameter of the inner surface of the cylinder faces each other. A support wall is formed, and at least the valve lifter sliding area of the valve lifter side wall surface of the support wall is formed flush with the inner surface of the valve lifter holding portion.

[Operation] In this structure, the lower part of the holding part is partially extended downward only at positions where the inner surfaces of the cylinder face each other. Therefore, the extended support wall does not significantly hinder the weight reduction of the engine. Since the support wall is continuous with the lower water jacket upper wall, the valve lifter holding portion is directly supported also on the water jacket upper wall, and the rigidity is significantly increased. Further, since the support walls are extended at positions facing each other on the inner diameter of the cylinder, the valve lifter is slidably supported from both sides, and the sliding position of the valve lifter is maintained in a predetermined position. Therefore, the rigidity of the valve lifter holding portion is improved and the sliding posture of the valve lifter is stabilized while the increase in weight due to the extension of the support wall is suppressed to a minimum. Further, since the support wall is connected to the upper wall of the water jacket, the molten metal around the valve lifter holding portion during casting becomes good.

[Embodiment] Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings.

1 to 3 show a cylinder head valve lifter holding structure according to a first embodiment of the present invention. In the figure, 1 shows a part of a cylinder head of an internal combustion engine having a direct drive type valve operating mechanism, and particularly shows the vicinity of a valve lifter holding portion of the cylinder head. Reference numeral 2 denotes a valve lifter holding portion in which the inner surface 3 of the cylinder is formed as a sliding surface for the valve lifter. In this embodiment, the valve lifter holding portion 2 is formed adjacent to the cam journal bearing portion 4. A part of the valve lifter holding part 2 is continuous with the cam journal bearing part 4, and the remaining part is the peripheral wall part 5.
In succession.

The lower part of the valve lifter holding part 2 is extended partially downward in the circumferential direction so as to be continuous with the water jacket upper wall 6 at a position where they face each other on the inner diameter of the cylinder of the valve lifter holding part. Form a support wall 7 that supports the valve lifter holding portion 2. The support wall 7 is partially provided in the circumferential direction only at the position where the inner circumferential surface of the cylinder faces each other, and is not provided over the entire circumference of the inner circumferential surface of the cylinder. The wall surface of the support wall 7 on the valve lifter side is formed so that at least a portion in the valve lifter sliding region is flush with the inner surface 3 of the valve lifter holding portion 2. Therefore,
The inner surface of the support wall 7 also forms a valve lifter sliding surface.

In the embodiment apparatus configured as described above, the valve lifter holding portion, which was conventionally supported by the cam journal bearing portion and the peripheral wall portion, is also supported by the water jacket upper wall 6 via the support wall 7. By the support by the support wall 7, the rigidity of the valve lifter holding portion 2 is significantly increased, and even when a large force is applied from the valve lifter, the predetermined sliding surface shape can be sufficiently maintained. As a result, the posture of the valve lifter is also stabilized, the sliding resistance between the valve lifter and the valve lifter is reduced, and the operation of the valve operating system becomes smooth.

Further, since the support wall 7 is only partially provided in the circumferential direction, the increase in weight can be suppressed to the minimum. Since the support walls 7 are provided at diametrically opposed portions, the valve lifter slides on its sliding surface while being supported from both sides in the diametrical direction, and the posture of the valve lifter is stabilized.

Further, since the support wall 7 connects between the valve lifter holding portion 2 and the water jacket upper wall 6, the support wall 7 portion is used as a runner when the cylinder head is cast, so that the hot water satisfactorily flows.
Occurrence of casting defects such as shrinkage cavities can be suppressed.

Next, FIG. 4 shows a second embodiment of the present invention. In the second embodiment, the valve lifter holding portion 11 provided on the cylinder head 10 is formed at a position apart from the cam journal bearing portion 12. Then, the support walls 14 similar to those of the first embodiment are provided at the positions facing each other on the diameter of the inner surface 13 of the valve lifter holding portion 11 in the cylindrical direction. Other configurations and operations are similar to those of the first embodiment.

[Advantages of the Invention] According to the valve lifter holding structure of the cylinder head of the present invention, a support wall continuous with the water jacket upper wall is provided at positions circumferentially partially opposed to each other on the inner diameter of the cylinder of the valve lifter holding portion. The rigidity of the valve lifter holding part can be improved while minimizing the increase in weight.The opposite support walls guide the valve lifter from both sides, and the inner surface of the support wall is flush with the inner surface of the valve lifter holding part. By forming the valve lifter, the sliding surface of the valve lifter can be lengthened and the posture of the valve lifter can be stabilized.

Further, by directly connecting the valve lifter holding portion having a large volume to the upper wall of the water jacket by the supporting wall, it is possible to prevent the occurrence of casting defects such as shrinkage cavities.

[Brief description of drawings]

1 is a longitudinal sectional view of a valve lifter holding structure for a cylinder head according to a first embodiment of the present invention, which is a sectional view taken along the line I--I of FIG. 2, and FIG. 2 is a plan view of the apparatus of FIG. FIG. 3 is a sectional view taken along the line III-III of FIG. 2, and FIG. 4 is a plan view of a valve lifter holding mechanism of a cylinder head according to a second embodiment of the present invention. 1, 10 ... Cylinder head 2, 11 ... Valve lifter holding part 4, 12 ... Cam journal bearing part 5 ... Peripheral wall part 6 ... Water jacket upper wall 7, 14 ... Support wall

Claims (1)

[Scope of utility model registration request] 1. A valve lifter holding portion formed in a cylinder head, having a cylindrical inner surface, wherein the cylindrical inner surface is formed as a sliding surface for a valve lifter, wherein a lower portion of the valve lifter holding portion is partially circumferentially formed. A support wall for the valve lifter holding portion is formed by extending the inner surface of the cylinder so as to be continuous with the upper wall of the water jacket at positions that face each other in diameter, and at least the valve lifter sliding area of the side wall surface of the valve lifter of the support wall. Is formed flush with the inner surface of the valve lifter holding portion.