JPH029087Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to the structure of a cylinder head, and more particularly to a rib structure on a top deck portion of a cylinder head of a multi-cylinder engine.

[Prior art]

In engines such as automobiles, a cylinder head is attached to the cylinder block, and in addition to forming intake passages and exhaust passages in the head, hollow spaces such as tappet insertion holes, water jackets, and even oil passages are formed in the head. It is formed into an extremely complex shape. Such a cylinder head is further formed with a plug boss section for attaching the spark plug and a bolt boss section for the head bolt, but the above-mentioned water jacket is formed between the top deck and the bottom deck inside the head, and Both decks are formed so as to connect the upper and lower portions between the bolt boss portions. The lower surface of the lower deck is a mating surface with the cylinder block, and is integrated with the cylinder block by a head bolt inserted into the insertion hole of the bolt boss portion with a gasket etc. in between.

Incidentally, since such cylinder heads are required to be lightweight, their rigidity tends to be low, but in order to increase the rigidity, continuous ribs are provided inside the head. −
It is described in Publication No. 89841. This is a rib that connects bolt bosses provided on the cylinder head around one cylinder bore and is approximately annular when viewed from above. By strongly pressing the installed gasket through its ribs, it is possible to maintain a high degree of airtightness.

Although such a cylinder head has the advantage of increasing the rigidity around the bore, it cannot suppress deformation of the cylinder head due to combustion heat in the engine. That is, in a multi-cylinder engine in which a plurality of cylinders are arranged, the cylinder head is also elongated in the direction in which the cylinders are arranged, and deformation due to combustion heat appears conspicuously in that direction. In such a case, the above-described rib structure does not exhibit a reinforcing effect in the arrangement direction, and cannot resist the deformation. Moreover, the exhaust passage side of the cylinder bore is heated more than the intake passage side due to the passage of combustion exhaust gas, and it is not possible to cope with thermal deformation in the direction perpendicular to the direction in which the cylinder bores are arranged. .

If the cylinder head is not reinforced to cope with the deformation of the head due to combustion heat, cracks will occur in the top deck part, which has a thin wall structure due to prioritizing weight reduction and creating space. A problem arises in that the engine cannot withstand long-term use and the reliability of the engine decreases.

[Purpose of invention]

The present invention was developed in view of the above-mentioned problems, and its purpose is to increase the rigidity of the cylinder head, which is subject to more severe thermal deformation than the cylinder block, in the direction of the bore arrangement and in the direction approximately perpendicular thereto. Therefore, it is possible to suppress the deformation of the upper deck portion, which has a relatively thin structure, and to prevent the occurrence of cracks at that portion. In addition, it also protects against localized impact on the cylinder head during the explosion stroke of each cylinder.
An object of the present invention is to provide a structure of a cylinder head that can increase its strength.

[Structure of the idea]

The cylinder head structure of the present invention is a cylinder head for a multi-cylinder engine in which a spark plug is placed almost in the center of the cylinder bore, and each plug boss part forming a spark plug insertion hole is connected in the arrangement direction of the cylinder bore. A first rib that intersects the first rib substantially orthogonally and connects each bolt boss portion, which has a mounting hole for a head bolt that fastens the cylinder head to the cylinder block, is attached to the upper deck portion. It is being formed.

〔Example〕

Hereinafter, the present invention will be described in detail based on examples thereof. FIG. 1 is a plan view of a cylinder head 1 to which the cylinder head structure of the present invention is applied, in which four cylinder bores 2 are arranged in a row in the left-right direction of the figure. In this example, two camshafts for opening and closing intake valves and exhaust valves (not shown) provided for each bore are attached, and bearing surfaces 3 and 4 are formed for each. . A tappet insertion hole 5 into which a tappet that is moved up and down by a cam of a camshaft is inserted is formed between the respective bearing surfaces 3 and 4.
In an engine in which two camshafts are arranged in this manner, due to the arrangement space within the cylinder head 1, the plug boss portion 7 in which the insertion hole 6 for attaching the spark plug for each cylinder is formed is It is installed approximately at the center of each cylinder bore 2. The plug boss portion 7 is connected to a cylindrical wall 8 forming a tapepet insertion hole 5 arranged in parallel to the plug boss portion 7 through a continuous hole 9 at the upper part of the head 1 as shown in FIG. has been done.

Between the cylinder bores 2 described above, there is a bolt boss portion 12 to which a head bolt 11 for fastening the cylinder head 1 to the cylinder block 10 is attached.
are arranged in parallel to the arrangement direction of the plug boss portions 7 as shown in FIG. Further, a cover retaining seat 13 for fixing a head cover (not shown) to the cylinder head 1 is provided between bolt bosses 12 that face each other in a direction perpendicular to the arrangement direction of the cylinder bores 2, as necessary. It is being Note that such a cylinder head 1 has an intake passage 14 (see Fig. 2) and an exhaust passage 15.
In addition, hollow spaces such as the above-mentioned tappet insertion hole 5, water jacket 16, and an oil passage (not shown) are formed, resulting in an extremely complicated shape. Then, a mating surface 18 is formed, which connects the lower part of the bolt boss part 12 described above and sandwiches the gasket 17 between the lower surface and the cylinder block 10.
There is a lower deck part 19 that forms a lower deck part 19, and a top deck part 20 that connects the upper part of the bolt boss part 12 and the lower part of the plug boss part 7 is formed above the lower deck part 19 so as to form a space for the water jacket 16 and the like.

In such a cylinder head 1, the wall thickness of the top deck part 20 is not very large, so on its upper surface, the first plug boss part 7 for the spark plug is connected in the arrangement direction of the cylinder bore 2. A rib 21 is formed. During the connection, the cover stopper 13 mentioned above is
If there is, it is also continuous and the first
The rib 21 extends, and the top deck portion 20 at the center of the cylinder head 1 is reinforced with one long rib. In addition, a second rib 23 is provided between each bolt boss portion 12 that intersects the first rib 21 almost perpendicularly and forms a mounting hole 22 for the head bolt 11 for fastening the cylinder head 1 to the cylinder block 10. is formed. Therefore, in the illustrated cylinder head 1, one rib in the arrangement direction of the cylinder bores 2 and a number of ribs extending in a direction perpendicular to that direction form the upper deck portion 20.
It is present on the upper surface of and reinforces the top deck portion 20 vertically and horizontally. In addition, a rib 24 parallel to the second rib 23 is provided on the upper surface of the continuous portion 9 at the top of the plug boss portion 7 of the spark plug, and the cylinder head 1 as a whole is reinforced three-dimensionally and its rigidity is improved. There is.

According to an embodiment with such a configuration, each rib resists deformation caused by combustion heat, preventing the occurrence of cracks in the head 1, and further reinforcing the ribs with each other, thereby increasing the rigidity of the cylinder head 1. be enhanced.

Thermal deformation in the cylinder head 1 first involves deformation in the direction in which the cylinder bores 2 are arranged. This deformation is caused by the fact that the cylinder block 10 is made of cast iron and has a water jacket with a large passage, so that the amount of thermal expansion is small.
The cylinder head 1, which is fastened by the cylinder head 1, is made of aluminum die-casting, which has relatively weak cooling and a high coefficient of thermal expansion. That is, even if the cylinder head 1 attempts to deform in the direction in which the bores 2 are arranged, it is restrained by the cylinder block 10, so that stress is generated in the cylinder head 1 in the direction in which the bores 2 are arranged. For such stress,
The first rib 2 on the top deck part 20
1 opposes this, and the stress burden acting on the top deck portion 20, which is formed as thin as possible, is reduced.

On the other hand, an intake passage 14 and an exhaust passage 15 are formed so as to sandwich one bore 2, but the passage is in a direction almost perpendicular to the arrangement direction of the bores 2, and the exhaust gas passing through the exhaust passage 15 is heated. The heat load acting on the head 1 is different between the exhaust passage side and the intake passage side. This deformation due to the difference in heat distribution cannot be countered by the first rib 21 described above, but is counteracted by the second rib 23 that connects the bolt boss portion 12. In this way, the thin-walled attachment part 20 is reinforced by the two intersecting ribs 21 and 23, and by mutually dispersing and sharing the force acting on the other rib, each rib is The reinforcing effect is enhanced, and the torsional strength of the cylinder head 1 is also improved.
In addition, since the plug boss portion 7 also has a rib 24 extending toward the cylindrical wall 8 of the tapepet insertion hole 5 at its upper portion, reinforcement in the direction perpendicular to the arrangement direction of the bores 2 is further enhanced.

By the way, the explosion strokes in the cylinder bores 2 are different in time. As a result, a force that pushes up the cylinder head 1 acts on each bore 2 each time there is an explosion. The above-mentioned first and second ribs 21 and 23 oppose this force in the upper deck portion 20 and function to attenuate the thrust force.

The above corresponds to the behavior based on engine operation, but from a manufacturing standpoint, it has the following advantages. That is, since the wall thickness of the upper deck portion 20 is reduced, hot water does not flow well when die-casting the cylinder head 1, and the strength of the upper deck portion 20 tends to be weaker than other parts. However, since the above-mentioned first rib 21 and second rib 23 are provided in the top decking section 20, the circulation of hot water in the top decking section 20 is improved through the portion forming the ribs, and the molding thereof is improved. It is done precisely and smoothly.
During casting, since the first ribs 21 extend in the direction in which the bores 2 are arranged, the hot water normally injected from one end can easily reach the other end.
Hot water is distributed from the second rib 23 to the peripheral area via the first rib 21, improving the flow of hot water throughout the head, resulting in a cylinder head of high quality.

[Effect of idea]

As can be seen from the description of the embodiments above, the present invention has the following features:
A first plug is attached to the top deck part of the cylinder head and connects each plug boss part in the direction in which the cylinder bores are arranged.
, and a second rib that intersects the first rib almost orthogonally and connects each bolt boss, so that the rigidity in the bore arrangement direction of the cylinder head and the direction almost orthogonal thereto is improved. is increased in the thick part. As a result, the deformation of the upper deck portion, which has a relatively thin structure, is suppressed, and the occurrence of cracks at that portion is also prevented. In addition, the damping effect against local impact on the head during each explosion stroke is enhanced, and the cylinder head can be made lightweight yet highly rigid and durable.

[Brief explanation of the drawing]

FIG. 1 is a plan view of an embodiment of a cylinder head to which the cylinder head structure of the present invention is applied;
FIG. 2 is an enlarged sectional view taken along the - line in FIG. 1. 1...Cylinder head, 2...Cylinder bore,
6...Insertion hole, 7...Plug boss section, 10...Cylinder block, 11...Head bolt, 12...
...Bolt boss part, 20...Atsupadetsuki part, 21
...First rib, 22...Mounting hole, 23...Second
ribs.

Claims (1)

[Claims for Utility Model Registration] In a cylinder head of a multi-cylinder engine in which a spark plug is disposed approximately at the center of the cylinder bore, a first head connecting each plug boss portion forming an insertion hole for the spark plug in the arrangement direction of the cylinder bore. and a second rib that intersects the first rib substantially perpendicularly and connects each bolt boss portion having a mounting hole for a head bolt for fastening the cylinder head to the cylinder block. The cylinder head structure is characterized by: