JP7092817B2 - cylinder head - Google Patents

Description

The present invention relates to a cylinder head constituting an engine for automobiles and the like.

A gasoline engine or a diesel engine includes a cylinder head as a main component of the engine body. The structure of the combustion chamber varies, but in the case of a gasoline engine, a pent-roof type recess with a constriction is formed in the cylinder head as part of the combustion chamber, and a pair of intake ports are formed on the inclined surface of the recess. It is common to open the outlet and the entrance of the exhaust port.

A valve seat is mounted on the intake port and the exhaust port, but the mounting portion (mounting hole) of the valve seat is formed with high dimensional accuracy by cutting (for example, Patent Document 1), and the valve seat and the valve. By forming the guide concentrically, sealing performance and durability are ensured. Therefore, when casting the cylinder head, a cutting allowance is provided around the intake port and the exhaust port.

Japanese Unexamined Patent Publication No. 62-156265

By the way, in order to improve the intake efficiency and the exhaust efficiency in the engine, it is preferable to make the inner diameters of the intake port and the exhaust port as large as possible. The outer diameter of is also large.

A tapered surface (valve recess) for allowing the valve to escape is formed around the intake port and around the exhaust port by cutting, and the valve seat is placed in a state surrounded by this valve escape tapered surface. However, if the diameters of the intake port and the exhaust port are increased, the distance between the intake port and the exhaust port becomes narrower, so that the valve relief tapered surface of the intake port and the valve relief taper surface of the exhaust port come into contact with the intake port. A chevron is formed in the part between the exhaust port and the exhaust port.

When a chevron is formed between the intake port and the exhaust port, there is a problem that the intake air hits the chevron in the intake stroke and the compression stroke to hinder the generation of the tumble flow, and the edge portion (ridge line) formed in the chevron becomes present. There is a concern that the temperature may rise excessively and become a heat point to easily induce knocking, or that the edge portion may fall off due to melting damage and damage the engine.

The present invention is intended to increase the diameter of the intake port and the exhaust port without causing such a problem.

The cylinder head of the present invention is
"A pent-roof type recess having a sloping surface constricted toward the opposite side of the cylinder block is formed, and a pair of intake ports and exhaust ports are provided on the sloping surface of the recess from the cylinder bore axis direction. It is formed so that it is located on the opposite side of the crank axis when viewed.
Valve seat mounting holes are formed in the intake port and the exhaust port. "
It has a basic structure.

And in the above basic configuration
"On the outside of both intake ports and the outside of both exhaust ports, valve relief tapered surfaces that are reduced in diameter toward the valve seat mounting holes are formed, respectively, and a portion between the intake port and the exhaust port. In addition, a virtual chevron portion sandwiched between the valve relief tapered surface of the intake port and the valve relief tapered surface of the exhaust port is located between the valve seat mounting hole of the intake port and the valve seat mounting hole of the exhaust port. It is designed to be positioned so as to protrude from the part of
Between the intake port and the exhaust port in a state where the virtual chevron portion is cut at the same height as the opening edge of the valve seat mounting hole in the intake port and the opening edge of the valve seat mounting hole in the exhaust port. A flat surface is formed in this part, with the crank axis direction as the anteroposterior direction, and the anteroposterior symmetrical shape and the anterior-posterior end edges are arcuate in the bottom view. "
It has the feature.

In the present invention, at the stage of casting the cylinder head, a cutting allowance is provided to form the valve seat mounting hole and the valve relief tapered surface by cutting, and at the stage of forming the valve relief tapered surface, the intake port and the intake port are provided. A chevron is formed between the exhaust port and the exhaust port. However, in the present invention, the chevron portion is cut off by a cutting tool such as an end mill, and the portion between the intake port and the exhaust port is a flat surface.

Therefore, the intake air ejected from the intake port smoothly flows toward the exhaust port without causing turbulence. This makes it possible to improve the function of generating the tumble flow in the intake stroke and the compression stroke. Further, since the chevron portion and the edge do not exist, the heat point phenomenon due to the excessive temperature rise does not occur. Therefore, problems such as induction of knocking and chipping due to melting damage can be solved.

Further, if a chevron remains between the intake port and the exhaust port, the size of the chevron portion may vary and the volume of the recess may also vary. However, the present invention eliminates the chevron portion. Therefore, it is possible to stabilize the quality (compression ratio) by eliminating the variation in volume. Further, if a chevron is present, burrs may remain on the edge, and there is a problem that it takes time to remove the burrs. However, in the present invention, even if burrs are generated, the chevron itself is cut off. Therefore, there is an advantage that the trouble of deburring can be eliminated.

It is a figure which shows the embodiment, (A) is a partial bottom view, (B) is the BB vertical sectional front view of (A). Both (A) and (B) are vertical sectional front views showing a manufacturing process (cutting process).

Next, an embodiment of the present invention will be described with reference to the drawings. The basic structure of the cylinder head 1 is the same as that of the conventional one, and a recess 3 having an inclined surface 2 whose diameter is reduced upward is formed concentrically with a cylinder bore (not shown) on the lower surface thereof.

On the inclined surface 2 of the recess 3, an intake port 4 (exit) and an exhaust port 5 (entrance) are opened in pairs on opposite sides of the crank axis when viewed from the direction of the cylinder bore axis. The pair of exhaust ports 5 are gathered together on the downstream side, but the pair of intake ports 4 may remain separated or may be gathered together on the upstream side.

A valve seat 6 is attached to each of the intake port 4 and the exhaust port 5. Therefore, the valve seat mounting holes 7 are formed in the intake port 4 and the exhaust port 5. Further, on the lower side (outside) of the valve seat 6, a downwardly widened valve relief tapered surface (valve recess) 10 for releasing the umbrella portions 8a and 9a of the valves 8 and 9 is formed.

Two inclined surfaces 11a and 11b having different spreading angles are formed on the inner surface of the valve seat 6, and the umbrella portions 8a and 9a of the valves 8 and 9 hit the connecting portions of the two inclined surfaces 11a and 11b and seal. It is supposed to be done. An ignition hole 12 for mounting a spark plug is opened in the central portion of the recess 3. Further, a cooling water jacket 13 is formed on the cylinder head 1.

In FIG. 1A, the intake port 4, the exhaust port 5, and the valve seat 6 are shown in a perfect circle, but since they are formed on the inclined surface 2, they are actually elliptical. The display of a perfect circle is for convenience to facilitate drawing.

By the way, the cylinder head 1 is a cast product made of aluminum, and in the intermediate product at the stage of casting, the concave portion 3 has a valve seat mounting hole 7 and a valve relief tapered surface as shown in FIG. 2 (A). A cutting allowance 14 for cutting 10 is formed. Then, as shown in FIG. 2B, first, the valve seat mounting hole 7 and the valve relief tapered surface 10 are machined by a cutting tool (not shown) such as an end mill or a milling cutter.

Then, when the diameters of the intake port 4 and the exhaust port 5 are increased, the distance between the intake port 4 and the exhaust port 5 is narrowed, and when the valve relief tapered surface 10 is machined, as shown in FIG. 2 (B). In addition, a chevron portion 15 having a ridge line 15a is formed in a region between the intake port 4 and the exhaust port 5 so as to protrude from the opening edge of the valve seat mounting hole 7. Therefore, by cutting the chevron portion 15 using the end mill 16 as shown in FIG. 2 (B), as shown in FIG. 1, the valve seat mounting hole 7 in the intake port 4 and the valve seat mounting hole in the exhaust port 5 The area between 7 and 7 is formed on the flat surface 17. The flat surface 17 has the narrowest width at the position where the distance between the intake port 4 and the exhaust port 5 is the narrowest , and spreads symmetrically in the front-rear and left-right directions when viewed from the crank axis direction. Further, since the processing is performed by the end mill 16, the front and rear edges have an arc shape when viewed from the bottom.

Then, if the chevron portion 15 remains, the intake air flows from the intake port 4 to the exhaust port 5 as shown by the dotted line in FIG. 2 (B), and the intake air collides with the chevron portion 15 to cause a flow. There are concerns about problems such as turbulence occurring and hindering the generation of tumble flow. However, if the chevron portion 15 is excised to form a flat surface 17 as in the present embodiment, the inspiratory flow is not obstructed, so that the intake air is taken in. It is possible to promote the generation of a tumble flow in the stroke and the compression stroke, and it is possible to eliminate the situation where knocking is induced or melted or dropped due to heat point formation.

Further, it is assumed that the size of the chevron portion 15 also varies due to the variation in casting and the variation in cutting. Therefore, if the chevron portion 15 remains, the volume of the recess 3 varies. However, in the present embodiment, the chevron portion 15, which is the cause of the variation, is cut off, so that the volume variation of the recess 3 can be eliminated and the quality can be stabilized. Even if burrs remain on the ridge line 15a, the chevron portion 15 disappears together with the burrs, so that the trouble of removing burrs can be saved.

Although the embodiments of the present invention have been described above, the present invention can be embodied in various ways. For example, a flat surface can be formed by cutting with a milling cutter.

The invention of the present application can be embodied in the cylinder head of an engine. Therefore, it can be used industrially.

1 Cylinder head 2 Inclined surface 3 Recessed part 4 Intake port 5 Exhaust port 6 Valve seat 7 Valve seat mounting hole 8 Intake valve 9 Exhaust valve 10 Valve relief tapered surface 14 Shaving allowance 15 chevron 16 End mill for forming a flat surface 17 Flat surface (flat part)

Claims (1)

A pent-roof type recess having a sloping surface constricted toward the opposite side of the cylinder block is formed, and a pair of intake ports and exhaust ports are viewed from the cylinder bore axis direction on the sloping surface of the recess. It is formed so that it is located on the opposite side of the crank axis.
A valve seat mounting hole is formed in the intake port and the exhaust port.
A valve relief tapered surface whose diameter is reduced toward the valve seat mounting hole is formed on the outside of both intake ports and the outside of both exhaust ports, respectively, at a portion between the intake port and the exhaust port. A virtual chevron portion sandwiched between the valve relief tapered surface of the intake port and the valve relief tapered surface of the exhaust port is located between the valve seat mounting hole of the intake port and the valve seat mounting hole of the exhaust port. It is designed to be positioned so that it protrudes from the part ,
Between the intake port and the exhaust port in a state where the virtual chevron portion is cut at the same height as the opening edge of the valve seat mounting hole in the intake port and the opening edge of the valve seat mounting hole in the exhaust port. A flat surface having a front-rear symmetrical shape and an arc-shaped front-rear edge is formed in the front -rear direction with the crank axis direction as the front-rear direction .
cylinder head.

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