JPS5933877Y2 - Automotive engine cylinder head - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of an engine cylinder head having a Siamese exhaust port.

Harmful unburned exhaust components HC and CO emitted from engines
Oxidizing (re-burning) these in the exhaust system is an effective exhaust purification means to reduce the exhaust gas, but in this case, it is preferable to maintain the exhaust temperature at a high temperature.

In order to reduce the dissipation of exhaust heat to the cylinder head as a countermeasure against high exhaust temperature, exhaust ports between adjacent cylinders of a multi-cylinder engine may be merged within the cylinder head to form a so-called Siamese exhaust port. be.

By the way, from the point of view of the airtightness of the engine combustion chamber or the durability of the engine, as shown in Fig. 1, the head bolts 1 that connect and fix the cylinder head and the cylinder block are fixed in order to obtain an even tightening force. It is necessary to arrange them equally for each cylinder al and a2, but when forming the exhaust Siamese port 2, the head bolt 1a passes through the inside of this port 2, so conventionally the dotted line As shown, bolts 1b were provided on both sides of the port 20.

However, this will cause the above-mentioned problems, resulting in undesirable results such as an increase in the number of bolts required for the housing and a complicated tightening work.

The present invention eliminates these drawbacks and provides a cylinder head that further improves the heat retention of Siamese ports.

This invention provides two spark plugs in each cylinder of a multi-cylinder engine, an exhaust gas recirculation device that recirculates a high rate of exhaust gas to the intake system, and a plurality of cylinder head bolts that surround each cylinder. On the other hand, exhaust ports between adjacent cylinders of the engine are merged within the cylinder head body to form a Siamese exhaust port, and the merging point of the Siamese exhaust ports is crossed over one of the plurality of cylinder head bolts. A port liner is placed outside the port and is installed within the port at a constant distance from the port wall.

Examples will be described below with reference to the drawings.

In FIG. 2, 10 is the cylinder head body, 11 is the combustion chamber of each cylinder, 12 is the intake port, 13 is the exhaust port, and exhaust ports N3 and 13 are the ones between adjacent cylinders that merge in the cylinder head body 10. Then, the Siamese Mist sural air port 14 is formed.

The cylinder head main body 10 is fixed to a cylinder block (not shown) by cylinder head bolts 15 arranged at equal intervals so as to surround each cylinder.

As is clear from FIGS. 3 and 4, the merging point 14a of the Siamese Mist exhaust port 14 is located outside the bolt hole 16 of the head bolt 15, on the side of the exhaust port that exists between the housing and cylinders. One of the cylinder head bolts 15 is formed so that the merging point 14a is located on the outer head end face side of the housing, so that the head bolt 15 can be arranged in the most favorable manner and uniform tightening force can be obtained. It has become.

Inside the exhaust port 14, a port 2 inner 17 having a substantially similar shape is disposed with a certain gap from the port wall, mainly by casting.

The port liner 17 has at least its inlet end and outlet end 1.
7a is supported by the port wall, but inside the merging point 14a, a 2.
It is joined only to the protrusions 18at18b at certain locations, avoiding contact with the boss portion 18 over the entire circumference, thereby reducing the amount of heat conducted to the cylinder head body 10.

Note that the contact with the port wall at the outlet end 17a is not made all the way around, but only partially, for the same reason.

On the other hand, each combustion chamber 11 of each cylinder is provided with two spark plugs 20 that ignite simultaneously, and is also provided with an exhaust gas recirculation device (not shown) that recirculates part of the exhaust gas during intake.

This exhaust recirculation device performs a high rate of exhaust recirculation, with a maximum value of 25 to 45%. However, despite the high rate of exhaust recirculation, the rapid combustion caused by the above-mentioned two-point ignition hinders engine operating performance. This makes it possible to significantly reduce the production of nitrogen oxides (NOx) without causing any damage.

As a result of the above, by using the Siamese exhaust port 14, the surface area around the entire circumference of the port is reduced compared to an independent exhaust port, and the temperature drop in the port is reduced because the high temperature exhaust from the two cylinders flows. Therefore, the amount of heat radiated from the exhaust gas to the cylinder head is reduced, thereby preventing a drop in exhaust gas temperature.

Additionally, due to the heat insulating action of the port liner 17, the effect of maintaining the exhaust gas temperature at a high temperature is extremely high. Therefore, the oxidation efficiency of unburned HC and CO in the exhaust system can be improved.

On the other hand, since the Siamese exhaust port 14 straddles the head bolt 15 and merges with it on the outside, in order to evenly tighten the cylinder head and cylinder block, it is necessary to use the conventional Siamese ported cylinder head. There is no need to change the position of the head bolts, and it is possible to fasten the head bolts efficiently with a minimum number of head bolts.

Considering that changing the location of the head bolts would require a major design change due to the water jacket formed inside the cylinder block, there is also the risk of reducing cooling efficiency. This is not a good thing, and the present invention eliminates such concerns.

As described above, according to the present invention, two spark plugs are provided in the combustion chamber to perform a high rate of exhaust gas recirculation to reduce NOx, and the exhaust port is made into a Siamese port to prevent a drop in exhaust temperature. HC, CO generated by high rate exhaust gas recirculation
is oxidized in the exhaust system, while the exhaust ports are merged on the outside by straddling the cylinder head bolts located between the exhaust ports, so there is no need to change the arrangement of the cylinder head bolts, and the cylinder head can be tightened evenly and efficiently. This prevents distortion of the cylinder head even when the cylinder pressure rises rapidly due to two-point ignition, and does not inhibit the formation of a water jacket that does not reduce the housing or cooling efficiency.

[Brief explanation of the drawing]

Fig. 1 is a schematic plan view of the conventional device, Fig. 2 is a schematic plan view of the present invention, Fig. 3 is a cross-sectional view of the Siamese exhaust port portion, and Fig. 4 is a sectional view taken along line l-I in Fig. 3. It is. 10... Cylinder head body, 11...
・Combustion chamber, 12...Intake port, 13...
...Exhaust port, 14...Siameseed exhaust port, 14a...Siameseed exhaust port confluence, 15...Cylinder head bolt, 1
6...Head bolt hole, 17...Port liner, 18...Boss part, 18a, 18b.
...protrusion.

Claims (1)

[Scope of utility model registration request] Two spark plugs are provided in each cylinder of a multi-cylinder engine, and an exhaust gas recirculation device is provided to recirculate a high rate of exhaust gas to the intake system, and a plurality of cylinder head bolts are disposed to surround each cylinder. Exhaust ports between adjacent cylinders of the engine are merged within the cylinder head body to form a Siamese exhaust port, and the meeting point of the Siamese exhaust ports is connected to the outside by tightening one of the plurality of cylinder head bolts. A cylinder header for an automobile engine, characterized in that a port liner is mounted within the port at a constant distance from the port wall.