JPH0426685Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an improvement in a cylinder head having an exhaust gas recirculation passage formed therein for recirculating part of the exhaust gas to the intake system.

[Conventional technology and its problems]

Generally, in internal combustion engines, the exhaust gas contains
In order to reduce NOx, part of the exhaust gas is recirculated to the intake system. Conventionally, the exhaust gas recirculation passage was provided outside the cylinder head, which caused the internal combustion engine to become larger. It was hot.

Therefore, as a prior art, Japanese Utility Model Application Publication No. 59-49755 aims to downsize internal combustion engines by forming an exhaust gas recirculation passage inside the cylinder head to recirculate part of the exhaust gas to the intake system. We are proposing to do so.

The exhaust gas recirculation passage in this prior art was provided so as to open in a tangential direction to a bent portion of the exhaust port at a portion of the ceiling surface within the exhaust port.

However, the exhaust gas from the combustion chamber flows out while bending along the curved part of the exhaust port, and as it curves along the exhaust port, carbon particles in the exhaust gas are moved around the outer circumference of the curved part by centrifugal force. Due to the tendency of the exhaust gas to be blown out to the side, the exhaust gas at the ceiling surface in the exhaust port contains a large amount of carbon particles. Opening the exhaust gas recirculation passage may cause a large number of carbon particles to enter the exhaust gas recirculation passage together with the exhaust gas, leading to frequent blockages of the exhaust gas recirculation passage, or reducing the amount of exhaust gas recirculation in the intake system from the internal combustion engine. The operation of the exhaust gas recirculation control valve, which controls the exhaust gas recirculation according to the load, etc., was frequently obstructed.

Moreover, opening the exhaust gas recirculation passage inside the cylinder head at the ceiling surface inside the exhaust port means that the exhaust gas recirculation passage is located further away from the meat part that forms the combustion chamber. In the cooling water jacket, it is necessary to provide a long built-up part for forming the exhaust gas recirculation passage, which increases the weight of the cylinder head and, by extension, the weight of the internal combustion engine. It turns out.

The present invention aims to solve this problem.

[Means for solving problems]

For this reason, the present invention provides a cylinder head in which an exhaust gas recirculation passage is formed that connects an intake port from the combustion chamber to one longitudinal side and an exhaust port from the combustion chamber to the other longitudinal side. A concave groove extending in the axial direction of the exhaust gas recirculation passage is formed on the inner bottom surface of the exhaust port, and the exhaust gas recirculation passage is opened in the concave groove.

[Functions and effects of the idea]

Exhaust gas from the combustion chamber flows out while curving along the curved part of the exhaust port, and as it curves along this exhaust port, carbon particles in the exhaust gas are pushed toward the outer periphery of the curved part by centrifugal force. Due to the tendency to be blown out, the exhaust gas at the inner bottom surface of the exhaust port contains less carbon particles, so a concave groove is formed on the inner bottom surface of the exhaust port as described above, By opening the exhaust gas recirculation passage to the intake system in the recessed groove, it is possible to introduce exhaust gas containing few carbon particles into the exhaust gas recirculation passage.

Furthermore, by opening the exhaust gas recirculation passage into the recessed groove provided on the inner bottom surface of the exhaust port, the exhaust gas recirculation passage approaches the meat part that forms the combustion chamber. The length of the built-up portion for forming the passage is shorter than that in the case where the exhaust gas recirculation passage is opened on the ceiling surface of the exhaust port as in the prior art.

Furthermore, by configuring the recessed groove to extend in the axial direction of the exhaust gas recirculation passage, the recessed groove can be used when forming the exhaust gas recirculation passage by drilling after the cylinder head is cast. Since this is a recess for the drill, it is extremely easy to form an exhaust gas recirculation passage that opens at the inner bottom of the exhaust port by drilling with a drill.

Therefore, according to the present invention, when the exhaust gas is recirculated through the exhaust gas recirculation passage formed in the cylinder head, the exhaust gas recirculation passage is prevented from being blocked by carbon particles, and the exhaust gas recirculation control valve is prevented from being blocked by carbon particles. It is possible to reliably reduce the operational obstruction due to
Moreover, the cost required for drilling the exhaust gas recirculation passage so that it opens at the inner bottom of the exhaust port after the cylinder head is cast can be reduced.

〔Example〕

Hereinafter, an embodiment of the present invention will be explained with reference to the drawings.
The upper surface shows a cylinder head fastened with a plurality of bolts 3, and the lower surface of the cylinder head 1 shows the following:
A combustion chamber 4 is recessed in each cylinder, and a cylinder head cover 5 covering camshafts 11 and 12, which will be described later, is removably fastened to the upper surface.

On one side 1a of the cylinder head 1 in the longitudinal direction parallel to the crankshaft, each combustion chamber 4 is provided.
An intake port 6 from each combustion chamber 4 is opened on the other side surface 1b in the longitudinal direction, and an intake valve 8 is provided at the opening of each intake port 6 to the combustion chamber 4. However, an exhaust valve 9 is provided at the opening of each exhaust port 7 to the combustion chamber 4, and a cooling water jacket 10 is formed within the cylinder head 1.

Further, in the upper chamber surrounded by the cylinder head 1 and the cylinder head cover 5, a camshaft 11 for each of the intake valves 8 and a camshaft 12 for each of the exhaust valves 9 are pivotally supported.

Reference numeral 13 indicates an exhaust gas recirculation passage for recirculating part of the exhaust gas to the intake system, and the exhaust gas recirculation passage 13 is formed by drilling from one side 1a of the cylinder head 1. The cylinder head 1 is formed by connecting the tips of one drill hole 14 and the other drill hole 15 formed by drilling from the other side surface 1b of the cylinder head 1 with each other. In addition,
Reference numerals 16 and 17 indicate build-up portions for both the drill holes 14 and 15 in the exhaust gas recirculation passage 13.

In the exhaust port 7 where one end of the exhaust gas recirculation passage 13 opens, a recessed groove 18 is formed on the inner bottom surface thereof so as to extend in the direction of the axis 15a of the other drilled hole 15 in the exhaust gas recirculation passage 13. Then, from this recessed groove 18, the other drill hole 15 is drilled using a drill.

With this configuration, the exhaust gas recirculation passage 13
Since the opening to the exhaust port 7 is located within the recessed groove 18 provided on the inner bottom surface of the exhaust port 7, exhaust gas containing few carbon particles can be introduced into the exhaust gas recirculation passage 1. In addition, the exhaust gas recirculation passage 13 is connected to the combustion chamber 4.
Therefore, the built-up parts 16 and 17 for forming the exhaust gas recirculation passage 13 need only be provided partially. When drilling the other drill hole 15 with a drill, this becomes a relief for the drill.

Note that when the other drill hole 15 in the exhaust gas recirculation passage 13 is bored from the other side surface 1b of the cylinder head 1, the opening of the drill hole 15 into the exhaust port 7 is provided with a hole approximately perpendicular to its axis. By forming the flat surface 19, it becomes easier to drill the exhaust gas recirculation passage 13 using a drill.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a diagram showing the main parts of the present invention, and FIG. 3 is a plan sectional view taken from - in FIG. 3. FIG. Figure 4 is an enlarged sectional view of Figure 1, Figure 5 is an enlarged sectional view of Figure 1.
FIG. 3 is an enlarged cross-sectional view. 1... Cylinder head, 1a... One side of the cylinder head, 1b... Other side of the cylinder head,
2...Cylinder block, 4...Combustion chamber, 6...
Intake port, 7...exhaust port, 13...exhaust gas recirculation passage, 18...concave groove.

Claims (1)

[Scope of utility model registration request] In a cylinder head having an exhaust gas recirculation passage formed therein that connects an intake port from the combustion chamber to one side in the longitudinal direction and an exhaust port from the combustion chamber to the other side in the longitudinal direction, the inner bottom surface of the exhaust port A cylinder head for an internal combustion engine, characterized in that a recessed groove extending in the axial direction of the exhaust gas recirculation passage is formed, and the exhaust gas recirculation passage is opened in the recessed groove.