JPH0640892Y2 - Cylinder head oil sump structure - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a structure of an oil sump formed in a cylinder head of an internal combustion engine for holding lubricating oil.

[Conventional technology]

In an engine having an overhead camshaft (OHC) structure and each cylinder having, for example, three intake valves, the cylinder head slides on a valve lifter attached to the upper ends of the valve stems of the three intake valves. Lifter guide holes for supporting freely are formed in close proximity to each other, and thin partition walls are formed between these lifter guide holes. In the cylinder head having such a structure, conventionally, the oil for lubricating the outer peripheral surface of the valve lifter and the inner peripheral surface of the lifter guide hole has been disclosed in JP-A-61-118901 or JP-A-60-192208. As disclosed in (1), the side portion of the lifter guide hole, that is, the lifter guide is held in an oil reservoir (formed at a portion J in FIG. 2) formed on the side receiving the thrust force.

[Problems to be solved by the device]

In the above-described conventional configuration, since the partition wall between the lifter guide holes is thin, there is a risk that strength may be reduced or cracks may occur due to stress concentration. In addition, the area of the inner peripheral surface of the lifter guide hole that supports the sliding surface of the valve lifter is reduced by the amount of the oil sump formed on the side of the lifter guide hole that receives the thrust force, which makes it easier for the valve lifter to be damaged. There's a problem.

[Means for Solving the Problems]

According to the present invention, in a cylinder head of an internal combustion engine in which a plurality of lifter guide holes are provided close to one cylinder, an upper end of a partition wall formed between the lifter guide holes has an arc-shaped cross section. It is characterized by forming an oil sump.

[Action]

Since the upper end of the partition wall is notched in a concave shape, stress concentration is eliminated. Further, since the oil sump is formed at the upper end of the partition wall, it is not necessary to form the oil sump on the side of the lifter guide hole that receives the thrust force, and the area of the support surface for the valve lifter becomes large.

〔Example〕

 The present invention will be described below with reference to the illustrated embodiments.

2 and 3 show a cylinder head 11 of an internal combustion engine to which an embodiment of the present invention is applied. This internal combustion engine is a so-called five-valve engine, and one cylinder 12 is provided with three intake valves and two exhaust valves. That is, the intake port 13 is divided into three at its tip, and the exhaust port 14 is divided into two at its tip.

The valve stem (not shown) of the intake valve is slidably supported by the stem guide 15, and the valve lifter (not shown) attached to the upper end of the valve stem has lifter guide holes 21,2.
It is slidably supported by 2,23. Similarly, the valve stem (not shown) of the exhaust valve is slidably supported by the stem guide 16, and the valve lifter (not shown) has a lifter guide hole.
It is slidably supported by 24 and 25. Each lifter guide hole 21,2
2, 23 are provided substantially along the axis of the camshaft (not shown), and the openings 13a, 13 for the intake port cylinder 12 are formed.
The b and 13c are arranged in an arc along the inner wall surface of the cylinder 12. Therefore, as understood from FIG. 2, the axes of the lifter guide holes 21 and 23 on both sides have the center lifter guide hole 22.
It is more inclined than the axis of. In addition, 17a, 17b, 17
C and 17d are cylinder head bolt mounting holes, and 18 is a spark plug hole. Further, 19a is a cam cap lower, and 19b is a cam cap upper.

FIG. 1 is an enlarged view of the lifter guide holes 21, 22, 23 and the vicinity thereof, and FIG. 4 is an enlarged view of a portion indicated by a symbol P in FIG. FIG. 5 is a vertical sectional view obtained by cutting the cylinder head 12 along a plane passing through the axis of the central lifter guide hole 22.

In these figures, partition walls 31 and 32 are formed between the lifter guide holes 21, 22 and 23. In the sectional view of FIG. 5, the thickness of these partition walls 31 and 32 is the same as the lifter on both sides. Since the guide holes 21 and 23 are more inclined than the lifter guide hole 22 in the center, they are larger toward the bottom. Oil reservoirs 33, 34 having an arcuate cross section are formed at the upper ends of the partitions 31, 32. The opening ends of the lifter guide holes 21, 22 and 23 are slightly expanded in diameter and are larger than the inner diameters of the lifter guide holes 21a, 22a and 23a.
It has become. The inner diameter of the lifter guide hole is determined by specifications such as the valve spring, the cam shaft, and the valve lift amount, and the inner diameter of the guide holes 21a, 22a, 23a is larger than the inner diameter of the lifter guide hole by about 1 mm.

The oil sumps 33 and 34 are part of a cylindrical surface or a spherical surface, and the center of curvature C thereof is located above the upper ends of the partition walls 31 and 32.
On the other hand, the center of rotation O of the camshaft is located at the intersection of the axis 22c of the lifter guide hole 22 and the axis 23c of the lifter guide hole 23, and the center of curvature C of the oil sumps 33, 34 is below this intersection O. It is located between the axes 22c and 23c. Oil sump 31
The upper end of 32 is formed deeper than the guide holes 21a, 22a, 23a. Therefore, as can be understood from FIG. 5, the plate thickness t of the oil reservoirs 33, 34 of the partition walls 31, 32 is thicker, which is about 1 mm thicker than when the oil reservoirs are not provided. The oil sump 33,
34 is molded by cutting or casting.

As described above, according to this embodiment, since the oil sumps 33, 34 are formed, the plate thickness of the upper ends of the partition walls 31, 32 is increased, and the oil sumps 33, 34 have a cylindrical surface or a spherical shape. For,
Stress concentration at the upper ends of the partition walls 31, 32 is prevented, and the strength performance of the partition walls is improved. Further, since the plate thickness of the upper end portion is increased, it is not necessary to reduce the diameter of the lifter guide hole or the guide hole, and therefore it is not necessary to increase the spring force of the valve spring to obtain a predetermined valve performance. Further, since the oil sumps 33 and 34 are formed on the upper ends of the partition walls 31 and 32 and not on the side of the lifter guide hole that receives the thrust force of the valve lifter, the inner peripheral surface of the lifter guide hole that supports the sliding surface of the valve lifter. The area of the valve is increased, and the valve lifter is prevented from being scratched. Further, the oil sump can hold a proper amount of lubricating oil for lubrication between the valve lifter and the lifter guide hole.

Although the oil sump is provided in the vicinity of the intake valve lifter guide hole in the above embodiment, it may be provided on the exhaust valve lifter guide hole side.

[Effect of device]

As described above, according to the present invention, since the upper end portion of the partition wall between the lifter guide holes has a large plate thickness and the oil sump, there is no risk of strength reduction or cracking due to stress concentration. Also, since it is not necessary to form an oil reservoir on the side of the lifter guide hole that receives the thrust force, the area of the inner peripheral surface of the lifter guide hole that supports the sliding surface of the valve lifter is increased, which prevents the valve lifter from being damaged. can do.

[Brief description of drawings]

FIG. 1 is a plan view showing a main part of a cylinder head to which an embodiment of the present invention is applied, FIG. 2 is a plan view showing an appearance of the cylinder head of FIG. 1, and FIG. FIG. 4 is a sectional view taken along line III, FIG. 4 is an enlarged view of a portion indicated by reference sign P in FIG. 3, and FIG. 5 is a sectional view taken along line VV in FIG. 11 …… Cylinder head 12 …… Cylinder 21,22,23 …… Lifter guide 31,32 …… Differential wall 33,34 …… Oil sump

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hideshi Hashizume, Toyota Town, Toyota City, Aichi Prefecture, Toyota Aichi (1) Toyota Motor Corporation (72) Inventor, Go Yamamura, Toyota City, Aichi Prefecture, Toyota City (1) 56) References: Open 63-75548 (JP, U) Open 60-41504 (JP, U)

Claims (1)

[Scope of utility model registration request] 1. A cylinder head of an internal combustion engine in which a plurality of lifter guide holes are provided close to each other for one cylinder, and an arc-shaped cross section is formed at an upper end portion of a partition wall formed between the lifter guide holes. The oil sump structure of the cylinder head is characterized by forming the oil sump.