JPH0612239Y2 - Cylinder head structure for sub-chamber engine - Google Patents

Description

The present invention relates to a sub-type cylinder head structure, and more particularly to a sub-chamber type cylinder head structure in which the periphery of the sub-chamber is surrounded by a water jacket.

(Prior Art) In a so-called sub-chamber engine in which a small sub-combustion chamber is provided above the engine combustion chamber, for example, from the viewpoint of improving the thermal stress distribution of the sub-chamber wall and suppressing the radiated sound from the outer wall of the combustion chamber, As disclosed in Japanese Laid-Open Patent Publication No. 60-54720, it has been proposed to provide a water jacket all around the sub chamber.

FIG. 5 is a vertical cross-sectional view showing a main part of a conventional vehicle sub-chamber cylinder head having the above-described structure. 1 is a cylinder head, 2 is a cylinder block, 3 is a cylinder bore,
Reference numeral 4 is a gasket interposed between the cylinder head 1 and the cylinder block 2. Lower surface 1 of cylinder head 1
In a, a sub chamber 5 is formed from this lower surface upward,
Further, a water jacket 6 is formed around the sub-chamber 5, and the sub-chamber 5 is in contact with the water jacket 6 through the peripheral wall 7 on the entire circumference. 8
Is a fuel injection nozzle mounting hole, and 9 is a glow plug mounting hole.

By the way, in the sub-chamber engine including the cylinder head 1 in which the water jacket 6 is formed all around the sub-chamber 6 as described above, in terms of strength of the core used when casting the cylinder head 1, Due to productivity problems, the width of the core cannot be made too narrow (if the width of the core is made too narrow, seizure of sand will occur), so the width of the water jacket 6 can be made smaller than a certain limit. could not.

For this reason, a large amount of cooling water flows into the water jacket portion 6a on the side opposite to the center side of the cylinder bore 3 with respect to the sub-chamber 5, thereby cooling the sub-chamber 5 more than necessary.
There is a problem that the cooling performance of the engine is deteriorated due to a shortage of the flow rate of the cooling water to the combustion chamber wall and the exhaust port wall on the center side of the cylinder bore 3 that requires sufficient cooling.

Further, in the cylinder head 1, a head bolt insertion hole for fastening and fixing the cylinder head 1 to the upper surface of the cylinder block 2 is provided at a position which faces the sub chamber 5 with the water jacket 6 interposed therebetween. Although the head bolt boss is formed, when the water jacket 6 is formed all around the sub-chamber 5, a part of the axial force of the head bolt passes through the transmission path that bypasses the ceiling wall of the water jacket 6. Moreover, most of them are transmitted as bending resistance of the ceiling wall. For this reason, the transmission efficiency of the axial force of the head bolt is low, the pressing force against the gasket 4 cannot be sufficiently obtained, and as a result, the sealing property at the mating surface of the cylinder head 1 and the cylinder block 2 is the portion where the sub chamber 5 is formed. There was also the problem of a decrease in.

(Purpose of the Invention) In view of the above situation, the present invention suppresses the flow rate of the cooling water flowing through the water jacket portion on the side opposite to the center side of the cylinder bore with respect to the sub chamber to cool the cylinder bore with a sufficient amount of cooling water. An object of the present invention is to provide a cylinder head structure for a sub-chamber engine, which is capable of supplying water so as to improve the cooling performance and the sealing performance at the mating surface between the cylinder head and the cylinder block.

(Structure of the Invention) The cylinder head structure of the sub-chamber engine according to the present invention is
A portion of the water jacket, which is formed so as to surround the sub chamber, on the side opposite to the center of the cylinder bore with respect to the sub chamber, a throttle wall for suppressing the flow rate of the cooling water passing through this portion is provided at the bottom of the water jacket portion. That is, on the cylinder block side, the head bolt boss, which faces the sub chamber close to the sub chamber with the water jacket in between, and the peripheral wall of the sub chamber are connected to each other, and a fuel injection nozzle mounting hole is provided near the upper portion of the water jacket. It is characterized by being provided.

(Effect of the Invention) According to the present invention, the auxiliary chamber is opposite to the center side of the cylinder bore without changing the width of the core used when casting and molding the cylinder head, that is, without sacrificing the productivity. Since it is possible to suppress the amount of water passing through the water jacket portion on the side, it is possible to secure the required amount of cooling water on the center side of the cylinder bore and prevent overcooling of the sub chamber. It is possible to improve efficiency.

Further, since the throttle wall is provided below the water jacket portion and by connecting the head bolt boss and the peripheral wall of the sub chamber, the tightening axial force of the head bolt is applied to the lower surface side of the cylinder head through the throttle wall. It is also possible to improve the sealing performance at the mating surface between the cylinder head and the cylinder block by transmitting the power.

Further, according to the present invention, the throttle wall is formed in the lower portion of the water jacket portion, and the cooling water is configured to pass above the throttle wall, so that the cooling water is provided near the upper portion of the water jacket portion. Since it flows near the fuel injection nozzle mounting hole provided, it is possible to prevent deterioration of the material on the fuel injection nozzle side near the mounting hole due to heat.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a cross-sectional view of a main part of a sub-chamber engine having a cylinder head structure according to an embodiment of the present invention, and FIGS. 2 and 3 are lines II-II and III-III in FIG. 5 is a vertical cross-sectional view in FIG. 5, and the portions corresponding to those in FIG. 5 are designated by the same reference numerals.

As is apparent from FIG. 1, the auxiliary chamber 5 is in contact with the water jacket 6 through the cylindrical peripheral wall 7 over the entire circumference thereof. Water jackets 6 are provided on both sides of the sub-chamber 5.
A head bolt boss 10 is formed so as to sandwich it. The head bolt boss 10 has a head bolt 1 at its axial center.
1 (see FIG. 2) is provided with a head bolt insertion hole 12 and an upper end surface thereof is a seat surface 13 for the head bolt 11. Therefore, the cylinder head 1 is fastened and fixed to the cylinder block side by the head bolt 11 attached to the head bolt boss 10 via the gasket. In addition, 14 is an exhaust port and 15 is an intake port.

Further, with respect to the sub chamber 5, in the water jacket portion 6a opposite to the center side of the cylinder bore, that is, in the water jacket portion 6a formed between the peripheral wall 7 of the sub chamber 5 and the outer wall 16 of the cylinder block 1, this portion is formed. A throttle wall 17 is provided for suppressing the flow rate of the cooling water passing through 6a. The throttle wall 17 is formed by connecting the head bolt boss 10 and the peripheral wall 7 of the sub chamber 5 on the line connecting the head bolt insertion holes 12 (in the cylinder row direction), and is clear from FIG. Thus, the throttle wall 17 is provided in the lower part of the water jacket portion 6a, and
The upper edge 17a of the diaphragm wall 17 is the lower surface 1a of the cylinder head 1.
It is formed so as to form an inclination angle of about 45 ° with respect to the center O of the upper sub chamber 5. The cooling water is configured to pass above the throttle wall 17. The fuel injection nozzle mounting hole 8 is provided near the upper portion of the water jacket portion 6a.

The reason why the diaphragm wall 17 is provided at the above-mentioned position is as follows. That is, when the cylinder head 1 is fastened and fixed to the upper surface of the cylinder block 2, the sub chamber 5 is arranged so as to straddle the cylinder bore in the radial direction. Therefore,
In order to secure a high level of sealability at the mating surface of the cylinder head 1 and the cylinder block 2 over the entire circumference of the cylinder bore, even in the portion where the sub chamber 5 is formed, the head bolt 11 is formed in the same manner as the other portions. A predetermined gasket pressing force needs to be applied by the fastening force. However,
When the cylinder head 1 is fastened to the cylinder block 2 with the head bolts 11 in the water jacket 6 formed around the sub-chamber 5 like the cylinder head 1, the sub-chamber 5 is formed around the sub-chamber 5 at the periphery thereof. Since the water jacket 6 serving as a hollow portion that inhibits the load transmission is formed, a part of the axial force of the head bolt 11 passes through the transmission path that bypasses the ceiling wall 18 of the water jacket 6 and most of the above. The bending resistance of the ceiling wall 18 is transmitted. Therefore, the axial force of the head bolt 11 directly acts as a compressive force on the cylinder head 1.
The axial force transmission efficiency is lower than that in the case of linear transmission to the lower surface 1a side of the cylinder, and a sufficient gasket pressing force cannot be obtained, resulting in a seal at the mating surface between the cylinder head 1 and the cylinder block 2. The property deteriorates in the portion where the sub chamber 5 is formed.

However, the diaphragm wall 17 is formed by connecting the head bolt boss 10 and the peripheral wall 7 of the sub chamber 5, and
Is formed in the lower portion of the water jacket portion 6a, the throttle wall 17 not only has the function of suppressing the flow rate of the cooling water passing through the water jacket portion 6a, but also has a tightening axial force of the head bolt 11. It is transmitted as a compressive force toward the lower surface 1a side of the cylinder head 1 through the throttle wall 17, and a large gasket pressing force can be secured, and the sealing performance at the mating surface between the cylinder head 1 and the cylinder block 2 is improved accordingly. It can be done.

Further, the throttle wall 17 is formed in the lower portion of the water jacket portion 6a so that the cooling water passes above the throttle wall 17, so that the cooling water flows in the vicinity of the fuel injection nozzle mounting hole 8 accordingly. Therefore, there is also an advantage that deterioration of the material around the mounting hole 8 on the fuel injection nozzle side due to heat can be prevented.

Next, FIG. 4 is a cross-sectional view showing a second embodiment of the present invention corresponding to FIG. 1, and parts corresponding to those in FIG. In this embodiment, the diaphragm wall 17 is formed closer to the outer wall 16 side of the cylinder head 1 than that of FIG. 1, and the side wall portion 19 of the cylinder head 1 linearly extending in the cylinder row direction is left as it is. It has a configuration in which it is linearly extended and connected to the peripheral wall 7 of the sub chamber 5. Also in this case, the throttle wall 17 is formed in the lower part of the water jacket portion 6a so that the cooling water passes above the throttle wall 17, and even with such a configuration, as in the first embodiment, In addition to suppressing the flow rate of cooling water, the diaphragm wall 17
Can function to transmit the tightening axial force of the head bolt 11 to the lower surface 1a side of the cylinder head 1.

[Brief description of drawings]

FIG. 1 is a transverse cross-sectional view of a main part of a cylinder head of a sub-chamber engine according to a first embodiment of the present invention, and FIGS. 2 and 3 are vertical cross-sections taken along lines II-II and III-III of FIG. Floor plan,
FIG. 4 is a horizontal cross-sectional view of a main part of a second embodiment of the present invention, and FIG. 5 is a vertical cross-sectional view of a main part showing a cylinder head of a conventional auxiliary chamber engine. 1 ... Cylinder head, 2 ... Cylinder block 3 ... Cylinder bore, 5 ... Sub chamber 6 ... Water jacket 6a ... Water jacket part 7 ... Sub chamber peripheral wall 8 ... Fuel injection nozzle mounting hole 10 ... Head bolt boss 11 …… Head bolt, 17 …… Throttle wall

Claims (1)

[Scope of utility model registration request] 1. A sub-chamber (5) is surrounded by a water jacket (6) formed around the sub-chamber (5), and at a position near the sub-chamber (5) with the water jacket (6) interposed therebetween.
Head bolt boss (10) with head bolt insertion hole (12)
In the cylinder head structure of the sub-chamber type engine, the cooling water passing through the water jacket portion (6a) to the water jacket portion (6a) on the side opposite to the center side of the cylinder bore with respect to the sub chamber (5). Restriction wall (1
7) is formed below the water jacket portion (6a) and by connecting the head bolt boss (10) and the peripheral wall (7) of the sub chamber (5), and the water jacket portion (6a) ) Near the top of the fuel injection nozzle
A cylinder head structure for a sub-chamber engine, characterized in that (8) is provided.