JPH085319Y2 - Engine cylinder head structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a cylinder head structure of an engine in which an exhaust gas recirculation passage is formed in a side wall of the cylinder head.

(Prior Art) Exhaust gas recirculation for returning a part of exhaust gas to an intake system in a so-called cross-flow type engine in which intake air is introduced from one end side of a cylinder head and exhaust gas is exhausted from the other end side When a passage (hereinafter, referred to as an EGR passage) is provided, if the EGR passage that connects the exhaust system and the intake system is formed by a pipe that is arranged so as to straddle the cylinder head, the passage length becomes long, In addition, the structure around the cylinder head becomes complicated. Further, a cooling device for cooling the high-temperature exhaust gas introduced from the exhaust system (hereinafter referred to as EGR gas) before being introduced into the intake system needs to be provided in the EGR passage, so a space for that is also required. . Moreover, if the EGR passage is provided through the water jacket of the cylinder head to cool the exhaust gas by the cooling water in the water jacket, the structure inside the cylinder head is complicated and the fabrication process is difficult. There is also a problem of blocking a part of.

Therefore, conventionally, as described in, for example, Japanese Utility Model Laid-Open No. 51-94321, there has been proposed one in which an EGR passage is formed along the water jacket on the side wall of the cylinder head. Since the side wall of the cylinder head has a relatively large space, the internal structure of the cylinder head will not be so complicated even if the EGR passage is formed here.
There is no problem of blocking the water jacket.

By the way, when the EGR passage is formed on the side wall of the cylinder head simply along the water jacket as described above, the wall area shared by the EGR passage and the water jacket is relatively small, and therefore the temperature of the exhaust gas is sufficient. There is a problem that it does not go down. Therefore, in order to enhance the cooling effect, it is conceivable that not only the EGR passage is arranged along the water jacket, but also the water jacket is bulged to actively increase the contact area between the water jacket and the EGR passage. , If you bulge the water jacket beyond the head bolt boss part,
The rigidity of the seal surface of the cylinder head is reduced around the bulge portion position, and the inconvenience that the required surface pressure cannot be obtained occurs.

(Purpose of Invention) The present invention has been made in view of the above problems,
An object of the present invention is to form an exhaust gas recirculation passage along the water jacket on the side wall of the cylinder head, to increase the cooling effect of the EGR gas as much as possible and to secure the sealing performance of the cylinder head sealing surface. .

According to the present invention, when the EGR passage is formed along the water jacket at the side wall position of the cylinder head, the passage wall of the EGR passage and the position of the core support hole boss come close to each other, and the core support hole is formed. Focusing on the fact that the boss can be used for reinforcement, even if the water jacket bulges beyond the head bolt boss to improve the cooling effect of EGR gas, the rigidity of the bottom wall of the cylinder head does not decrease and seals. We have found a concrete means that can ensure the security, and its structure is as follows. That is, in the cylinder head structure of the engine according to the present invention, the exhaust gas recirculation passage is formed on the side wall of the cylinder head so as to pass along the water jacket and above the cylinder support hole boss, and the water jacket is formed. Along the exhaust gas recirculation passage, the cylinder head is bulged below the cylinder support hole boss to the outside of the head bolt boss, and the bulged portion of the cylinder head bottom wall and the exhaust gas recirculation It is characterized in that the wall portion of the circulation passage is connected by the core supporting hole boss.

(Function) EGR gas is taken out from the exhaust system of the engine, cooled in the EGR passage formed in the side wall of the cylinder head by the cooling water flowing through the water jacket and its bulging portion, and then introduced into the intake system.

Since the EGR passage is close to the water jacket and its bulging portion in a wide range, a large amount of heat is taken from the EGR gas by the cooling water, so that the temperature drop of the EGR gas is large.

In addition, the bottom wall of the cylinder head is a core support hole boss with high rigidity at the bulging portion of the water jacket,
Since it is connected to the wall of the passage, the rigidity of the sealing surface on the bulging portion side is high. Therefore, the sealing performance of the cylinder head sealing surface by tightening the head bolt is secured.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

1 and 2 are a bottom view and a side view of a cylinder head of an engine according to an embodiment of the present invention.

The engine of this embodiment is a four-valve cross-flow type engine having two intake valves and two exhaust valves in each cylinder, and as shown in FIG. 2 is formed, and two intake ports 3a, 3b are formed in the combustion chamber recess 2 toward one end of the cylinder head 1.
Is open, and the two exhaust ports 4a and 4b are open toward the other end side. Further, a spark plug mounting hole 5 is opened at a central position of the combustion chamber recess 2.

The EGR passage 6 is integrally formed by expanding the rear side wall 7 of the cylinder head 1. The rear side wall 7 of the cylinder head 1 has the bulging portion at the EGR passage 6
To the bottom wall 8 of the cylinder head 1,
As a result, the water jacket 10 that bulges to the outside of the head bolt boss portions 9a, 9b on the side end side along the EGR passage 6
To form a bulging portion 10a.

Therefore, the EGR passage 6 comes into contact with the water jacket 10 and its bulging portion 10a over a wide range, and
The effect of gas cooling is great. Further, at the one end side and the other end side of the cylinder head 1 through which the intake ports 3a, 3b and the exhaust ports 4a, 4b penetrate, the water jacket 10 originally has the head bolt boss portions 9a, 9b, as shown in FIG. 9
Although it is formed so as to extend to the outside of c and 9d, the water jacket 10 is further bulged to the rear side of the cylinder head 1 to surround the rear end head bolt boss portions 9a and 9b. Since the water jacket 10 is connected as described above, the flow of the cooling water becomes smooth, which also promotes the cooling of the EGR gas. Further, the effect of cooling the cylinder head 1 itself is enhanced by improving the flow of water in the water jacket 10.

In addition, a core support hole 11 used during casting is provided in the center of the lower portion of the side wall 7 of this bulging portion, and the EGR passage 6
Is curved upward so as to bypass the boss portion 12 of the core support hole 11 on the way, and at the curved position, the wall portion 13 of the EGR passage 6 is connected to the cylinder head bottom wall 8 by the core support hole boss portion 12. It is connected. The core support hole 11 is closed by driving a blind plug.

In this way, since the cylinder head bottom wall 8 and the wall portion 13 of the EGR passage 6 are connected by the core support hole boss portion 12, the head bolt boss portions 9a, 9 on the rear side of the cylinder head 1 are formed.
The rigidity of the bottom wall 8 and the sealing surface 14 of the portion protruding outward from b is increased, and the required sealing surface pressure is obtained.

A blow-by passage 15 is formed in the cylinder head 1 from the sealing surface 14 side, and three oil galleries are formed penetrating the upper part of the cylinder head 1 in the cylinder row direction.
16,17,18 are provided. These oil galleries 1
The open ends of 6, 17, and 18 are closed by plugs (not shown), and the first of them is close to the exhaust side end surface of the cylinder head 1.
The oil gallery 16 is communicated with an oil inlet 19 projecting from the rearmost end of the exhaust side end face. Also, the oil inlet 19
The oil passage 20 provided on the extension of the first oil gallery 16 and extending orthogonally to the first oil gallery 16 passes through the reservoir chamber 21 formed at the top of the cylinder head 1 and the second and third oil passages in the central portion.
It is connected to the oil galleries 17 and 18. Oil inlet 1
The lubricating oil from 9 to the first oil gallery 16 is supplied to the cam journal (not shown) on the exhaust side, and the oil sent from the oil inlet 19 to the oil passage 20 is the second oil gallery. The oil is supplied from 17 to a hydraulic end pivot for an exhaust valve (not shown), and from a third oil gallery 18 to a hydraulic end pivot for an intake valve and a cam journal (neither shown).

Needless to say, the present invention is not limited to the above-described oil supply structure.

Further, the present invention is not limited to the four-valve type engine as in the above embodiment, and can be naturally applied to a two-valve type engine and the like.

Furthermore, the present invention can be applied to engines other than the cross flow type.

(Effect of the Invention) Since the present invention is configured as described above, it is possible to enhance the effect of cooling the EGR gas by the EGR passage formed on the side wall of the cylinder head and to secure the sealing property of the cylinder head sealing surface. .

[Brief description of drawings]

FIG. 1 is a bottom view of a cylinder head according to an embodiment of the present invention, and FIG. 2 is a rear side view of the cylinder head. 1: Cylinder head, 6: Exhaust gas recirculation passage, 7: Side wall, 9
a, 9b, 9c, 9d: head bolt boss portion, 10: water jacket, 10a: bulge portion, 12: core support hole boss portion, 13: wall portion, 14:
Sealing surface.

Continuation of front page (72) Inventor Noriko Kaneda 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd. (56) References: 57-31560 (JP, U)

Claims (1)

[Scope of utility model registration request] 1. An exhaust gas recirculation passage is formed on a side wall of the cylinder head so as to pass along the water jacket and above the cylinder support hole boss above the cylinder head, and the water jacket is provided along the exhaust gas recirculation passage. On the cylinder head lower side of the core support hole boss to the outside of the head bolt boss portion, and the bulged portion of the cylinder head bottom wall and the exhaust gas recirculation passage wall portion are An engine cylinder head structure characterized by being connected by a core support hole boss.