JP2544959Y2 - Cylinder head structure of internal combustion engine - Google Patents

Description

[Detailed description of the invention] [Object of the invention] <Industrial application field> The invention relates to a cylinder head structure of an internal combustion engine, in particular, a side wall and an upper deck are connected by a rib, and lubricating oil is provided on the upper deck. The present invention relates to a cylinder head structure of an internal combustion engine in which a return passage is open.

<Conventional technology> The cylinder head of an internal combustion engine is
A valve mechanism for controlling the flow of exhaust gas is provided, and a hollow portion such as a water jacket and a passage for lubricating oil is formed, and the structure is extremely complicated.

In such a cylinder head, it is customary to provide ribs at important points in order to ensure rigidity or to increase the efficiency of running the molten metal during casting (see Japanese Utility Model Application Laid-Open No. 61-181844).

On the other hand, the lubricating oil that has lubricated the valve mechanism is collected in the oil pan via a return passage formed in the cylinder head. However, the amount of the lubricating oil is substantially reduced, and the service life of the lubricating oil is extended. Furthermore, it is preferable that the lubricating oil can be recovered as quickly as possible.

<Problem to be solved by the invention> However, depending on the structure of the rib, the inside of the cylinder head may be partitioned into several small rooms. In such a case, in order to prevent the lubricating oil from staying in the cylinder block partitioned by the ribs, it is necessary to provide a return passage for each partitioned portion, which complicates the structure and complicates the machining process. Forced to.

The present invention has been devised in order to solve such inconveniences, and its main purpose is to lubricate both sides of the partition ribs without complicating the structure and complicating the processing steps. An object of the present invention is to provide a cylinder head structure of an internal combustion engine improved so as to be able to communicate an oil return passage.

Configuration of the Invention <Means for Solving the Problems> In order to solve the above problems, a cylinder head structure of an internal combustion engine according to the present invention has a cam bearing portion formed between adjacent cylinders and a cylinder. A cylinder head structure of an internal combustion engine in which a return passage for lubricating oil is formed to communicate with a side wall of a head and a valve mechanism chamber surrounded by an upper deck, and between each side wall facing each other in a cylinder row direction, Reinforcing ribs connecting the respective side walls to the cam bearing portion and the upper deck are erected in a wall shape on the upper deck, and adjacent valve operating mechanism chambers partitioned by the ribs are respectively formed on the upper deck. A communication passage for communication is formed below the rib, and a single common hole for a return passage of the lubricating oil having an upper end opened in the communication passage immediately below the rib. It was made.

It is preferable that the ribs protrude upward from the upper deck and connect the opposing head bolt bosses, and also connect the head bolt bosses and the side walls.

<Embodiments> Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIGS. 1 and 2 show a cylinder head for a four-cylinder engine constructed according to the present invention. The cylinder head 1 is configured for a so-called DOHC engine in which an exhaust valve and an intake valve are driven by separate camshafts. A lower cam for supporting a camshaft is provided at the top of the cylinder head 1. Two rows of caps 2a and 2b are arranged along the cylinder row direction. These two rows of lower cam caps 2a and 2b
Bolt holes 3 and 4 for fixing the upper cam cap are formed on both sides of the journal portion 5 on the upper surface of the journal portion 5, respectively.

An insertion hole 6 for supporting a rocker shaft pivotally supporting a rocker arm is formed in an inner portion below the journal portion 5 of both lower cam caps 2a and 2b in parallel with the center line C in the cylinder row direction. Have been.

A valve stem guide 8 is fitted to the center of the upper deck 7 defining the bottom wall of the valve mechanism chamber so that two intake valves and exhaust valves can be attached to each cylinder. Are formed adjacent to each other with the center of the cylinder bore interposed therebetween. A spark plug mounting hole 10 is provided at a position corresponding to the center of each cylinder bore (FIG. 2).

Head bolt bosses 12a and 12b formed with a bolt hole 11 for inserting a head bolt for fastening the cylinder head 1 to the cylinder block are provided between the plug mounting holes 10 on the upper surface of the upper deck 7. It is provided immediately below the center of the journal section 5. And both lower cam caps
A through hole 13 for inserting a bolt fastening tool from the journal portion 5 toward the head bolt bosses 12a and 12b is provided coaxially with each of the bolt holes 11 at the center of the 2a and 2b.

A water jacket 15 is formed between the lower deck 14 and the upper deck 7, which form a joint surface with the cylinder block, between the first and second cylinders, and between the third and fourth cylinders. Between them, there is formed an extraction hole 17 for core sand closed by a sealing bolt 16.

Further, an oil passage 18 for supplying lubricating oil to the journal portion 5 is formed between the second cylinder and the third cylinder.

Now, in order to stabilize the operation of the valve operating mechanism, it is preferable that the rigidity of the cylinder head 1 be as high as possible.
On the other hand, there is a strong demand for thinner walls while promoting weight reduction. Therefore, in the present embodiment, the head bolt bosses 12a and 12b opposed to each other with the cylinder line direction center line C interposed therebetween are provided with two ribs 19 at appropriate intervals in the cylinder line direction.
a ・ 19b and head bolt bosses 12a ・ 12b
And the side wall 1a of the cylinder head 1 is also connected by a rib 20.

In this way, the head bolt bosses 12 facing each other
By connecting a and 12b to each other with two ribs, a portion having a box-shaped cross section is formed at the same portion, and high rigidity can be obtained in the torsion direction as well as in the cylinder row direction in particular. At the same time, the above-mentioned core sand extraction hole 17 and lubricating oil path 18 are provided on the center line in the cylinder row direction, but these are sandwiched between the two ribs 19a and 19b, and the rigidity is increased. It is possible to easily balance the securing of the layout with the degree of freedom in layout.

Furthermore, the head bolt bosses 12a and 12b and the cylinder head 1
The ribs 20 are also connected to the side wall 1a to effectively reinforce the side wall 1a.

The cylinder head 1 is connected and fixed to the cylinder block via the head bolt bosses 12a and 12b.
Can obtain the highest rigidity in the head bolt bosses 12a and 12b. Therefore, in this embodiment, as shown in FIG. 3, the lower cam caps 2a and 2b are disposed immediately above the head bolt bosses 12a and 12b, and are connected to the head bolt bosses 12a and 12b. The ribs 19a, 19b, 20 are both connected to the lower cam caps 2a, 2b.
By doing so, the rigidity of the lower cam caps 2a and 2b can be extremely efficiently increased, in addition to the fact that the height of each of the ribs 19a, 19b and 20 can be increased.

By the way, when the ribs 19a, 19b, and 20 are provided so as to connect the upper deck 7 and the side wall 1a as described above,
Due to a, 19b, and 20, a plurality of small chambers are defined in the valve train chamber, and there is a problem in collecting the lubricating oil from each part to the oil pan.

Therefore, in the present invention, the head bolt bosses 12a and 12b
A drill hole 21 extending from the lower deck 14 side to the base end of the rib 20 is formed toward an intermediate portion of the thickness of the rib 20 connecting between the rib 20 and the side wall 1a of the cylinder head 1. At this time, by using a drill having a diameter sufficiently larger than the thickness dimension of the rib 20, a passage communicating with both sides of the rib 20 can be formed by one drill hole. In this case, as shown in FIG. 4, the drill tip P may be processed so as to slightly protrude into the base end of the rib 20, or as shown in FIG. A predetermined clearance is provided at a root portion of the rib 20 with respect to the upper deck 7 by forming a cast hole 22 in advance at the end,
The drill hole 21 may be made to penetrate from the lower deck 14 so that the tip P reaches the cast hole 22.

[Effects of the Invention] In the invention of the present invention having the above-described configuration, both side walls are reinforced by connecting the upper deck and the cam bearing portion via the ribs provided in the shape of a wall, so that the rigidity of the entire cylinder head including the cam bearing portion is reduced. It can be improved effectively.

The adjacent valve operating chambers separated by ribs are formed in a communication passage (clearance) formed below the rib and an upper deck immediately below the rib in such a manner that an upper end is opened in the communication passage. Since the lubricating oil return passage is formed by communicating with the single common hole, the lubricating oil can be moved through the single common hole without providing a separate return passage for each valve mechanism chamber. It is possible to uniformly and reliably recover from the valve mechanism chamber.

Further, even when the blow-by gas rises through the return passage, the blow-by gas collides with the bottom surface of the rib provided in the center of the upper end side of the return passage, so that an oil separating effect can be expected.

Further, according to the configuration in which the head bolt boss portions facing each other via the rib protruding upward from the upper deck and the connection between each head bolt boss portion and each of the side walls are provided, the ribs are provided on the rigid head bolt boss portions. Are connected, the rigidity of the cam bearing portion and the side wall can be greatly improved.

Further, if a predetermined clearance is provided at the base of the rib with respect to the upper deck, the opening area of the lubricating oil return passage becomes large, so that the lubricating oil can be more quickly collected.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view (a II line in FIG. 2) of a cylinder head according to the present invention cut along a cylinder bore, and FIG. 2 is a cross-sectional view along a II-II line in FIG. It is. FIG. 3 is a perspective view of a main part, partially cut away. FIG. 4 is a partial sectional view taken along the line IV-IV of FIG. 2 according to the first embodiment, and FIG. 5 is a partial sectional view similar to FIG. 4 according to the second embodiment. DESCRIPTION OF SYMBOLS 1 ... Cylinder head 2a ・ 2b ... Lower cam cap 3.4 ... Bolt hole, 5 ... Journal part 6 ... Insertion hole, 7 ... Upper deck 8 ... Valve stem guide 9 ... Valve mounting seat, 10 ... Ignition plug mounting hole 11 ... Bolt Holes 12a / 12b: Head bolt boss 13: Through hole, 14: Lower deck 15 ... Water jacket 16 ... Sealing bolt 17 ... Extraction hole, 18 ... Oil passage 19a / 19b / 20 ... Rib 21 ... Drill hole, 22 ... Cast hole

Claims (2)

(57) [Scope of request for utility model registration] An internal combustion engine having a cam bearing formed above adjacent cylinders and a lubricating oil return passage communicating with a valve mechanism chamber surrounded by a side wall of a cylinder head and an upper deck. It is a cylinder head structure, and between each side wall facing each other in the cylinder row direction,
Reinforcing ribs connecting the respective side walls to the cam bearing portion and the upper deck are erected in a wall shape on the upper deck, and adjacent valve operating chambers separated by the ribs are respectively arranged on the upper deck. A communication passage for communication is formed below the rib, and a single common hole for the lubricating oil return passage having an upper end opening in the communication passage is formed immediately below the rib. Cylinder head structure of internal combustion engine. 2. A cylinder for an internal combustion engine according to claim 1, wherein said ribs project upward from the upper deck and connect the head bolt boss portions facing each other, and connect the head bolt boss portions to the side walls. Head structure.