JP7516913B2 - Cylinder head for internal combustion engine and method for manufacturing the cylinder head for internal combustion engine - Google Patents

Description

The present invention relates to a cylinder head for an internal combustion engine and a method for manufacturing a cylinder head for an internal combustion engine.

In water-cooled internal combustion engines, a structure in which cooling water flows from the cylinder block to the cylinder head has been known for some time.

For example, Patent Documents 1 and 2 disclose a configuration in which the cooling water in the cylinder block flows from the cylinder block side to the cylinder head side along the cylinder axis.

In Patent Documents 1 and 2, the cooling water passage on the cylinder head side is formed so that the cross section along the plane including the cylinder axis of the inlet where the cooling water is introduced from the cylinder block is substantially L-shaped (crank-shaped).

Japanese Patent Application Publication No. 5-321662 Japanese Utility Model Publication No. 63-323589

However, in Patent Documents 1 and 2, the flow of cooling water introduced into the cylinder head is blocked by the L-shaped wall surface of the introduction section.

In other words, in Patent Documents 1 and 2, the cooling water collides with great force against the wall surface of the approximately L-shaped portion at the inlet of the cylinder head side cooling water passage. Therefore, in Patent Documents 1 and 2, the flow of the cooling water is disturbed at the inlet, and there is a risk of an increase in water flow resistance.

The cylinder head of an internal combustion engine according to the present invention is characterized in that a water jacket is formed inside the cylinder head, and the cooling water introduction passage of the water jacket has a curved portion that is curved at a predetermined curvature and opens into a lower deck of the cylinder head. The curved portion is curved so that the cooling water flowing along the curved portion is directed toward the upper part of the cylinder head. The cooling water introduction passage is formed to follow the shape of a bottom surface of a cavity that forms a part of the combustion chamber, and opens into the lower deck with an outer circumferential inner wall surface and an inner circumferential inner wall surface of the curved portion, which are part of the inner wall surface of the cooling water introduction passage, inclined with respect to the lower deck when viewed in the cylinder row direction of the internal combustion engine.

The cylinder head of the present invention can reduce passage resistance in the cooling water inlet passage by using the curved portion.

1 is a cross-sectional view of a main portion of a cylinder head of an internal combustion engine according to the present invention. FIG. 4 is a cross-sectional view of a cylinder head according to a comparative example of the present invention. FIG. 2 is a bottom view of a core used when casting a cylinder head of an internal combustion engine according to the present invention.

Below, one embodiment of the present invention will be described in detail with reference to the drawings.

Figure 1 is a cross-sectional view of a main part of a cylinder head 1 of an internal combustion engine according to the present invention, and is a cross-sectional view of the cylinder head 1 corresponding to a position along line A-A in Figure 3.

As shown in FIG. 1, the cylinder head 1 of an internal combustion engine has a generally rectangular cross section and has one side 2 to which exhaust parts (not shown) are attached, the other side 3 to which intake parts (not shown) are attached, a flat upper deck 4 that forms the top surface, and a flat lower deck 5 that forms the bottom surface.

The cylinder head 1 is made of, for example, an aluminum alloy. The cylinder head 1 is configured so that the exhaust from each cylinder is merged internally, and the merged exhaust flows through the exhaust components. In other words, the cylinder head 1 has an exhaust collection section (not shown) formed inside that collects the exhaust from each cylinder. The exhaust components are, for example, an exhaust turbo or a manifold catalyst. The intake components are, for example, an intake manifold. Note that the cylinder head 1 may be configured so that, for example, the exhaust from each cylinder is not merged internally, and an exhaust manifold is attached to one side surface 2 as an exhaust component.

The upper deck 4 of the cylinder head 1 is formed with a camshaft support portion 6 that rotatably supports the camshaft (not shown) together with a cam bracket (not shown).

The lower deck 5 of the cylinder head 1 has a cavity 7 that forms the upper part of the combustion chamber. The lower deck 5 is attached to the top surface of the cylinder block (not shown).

The cavities 7 form part (upper part) of the combustion chamber of the internal combustion engine, and are formed in the lower deck 5 in the same number as the number of cylinders. The cavities 7 cover the upper ends of the cylinders (not shown) of the cylinder block (not shown).

The cylinder head 1 also has a water jacket 8 formed therein through which cooling water flows. The water jacket 8 is located between the upper deck 4 and the lower deck 5 in the direction along the cylinder shaft axis C.

The water jacket 8 is formed to cover the periphery of the cavity 7, and the cooling water introduced from the cylinder block flows through it.

The water jacket 8 has a cooling water inlet passage 9 into which cooling water supplied from the cylinder block flows in from one end.

The cooling water introduction passage 9 has a curved portion 10 that is curved at a predetermined curvature. The curved portion 10 constitutes one end of the cooling water introduction passage 9 and opens into the lower deck 5 of the cylinder head 1. In other words, the cooling water introduction passage 9 opens into the lower deck 5 of the cylinder head 1.

The cooling water introduction passage 9 opens between one side surface 2 of the cylinder head 1 and the cavity 7. The cooling water introduction passage 9 opens at a position adjacent to the cavity 7.

The cooling water inlet passage 9 is connected to a cooling water passage that opens into the upper deck of the cylinder block (not shown) and is the inlet for the cooling water that flows into the water jacket 8 from the cylinder block side. The opening 9a of the cooling water inlet passage 9 formed in the lower deck 5 of the cylinder head 1 faces the opening of the cooling water passage formed in the upper deck (not shown) of the cylinder block (not shown).

As shown in FIG. 1, the cooling water introduction passage 9 is formed to follow the shape of the bottom surface 7a of the cavity 7. More specifically, the cooling water introduction passage 9 is curved from one side surface 2 of the cylinder head 1 toward the other side surface 3. Furthermore, the cooling water introduction passage 9 is formed to be curved with a predetermined curvature on a plane perpendicular to the cylinder row as shown in FIG. 1.

As shown in FIG. 1, the curved portion 10 is formed so that the outer circumferential inner wall surface 10a on the outer circumferential side (outside) of the curved portion 10 and the inner circumferential inner wall surface 10b on the inner circumferential side (inside) of the curved portion 10 each have a predetermined curvature.

As shown in FIG. 1, the inner wall surface 11 of the cooling water introduction passage 9 is formed so as to be smooth and continuous along the direction in which the cooling water flows, without any sharp edges. In the present specification, the inner wall surface 11 includes the inner wall surfaces 10a and 10b of the curved portion 10.

The cooling water introduction passage 9 opens with a portion of the inner wall surface 11 tilted relative to the lower deck 5. That is, the cooling water introduction passage 9 opens with the outer circumferential inner wall surface 10a and the inner circumferential inner wall surface 10b of the curved portion 10 tilted relative to the lower deck 5.

The curved portion 10 is formed so that the center of curvature of the curved portion is located below (on the cylinder block side) the lower deck 5. In other words, as shown in FIG. 1, the curved portion 10 is formed so that the center of curvature of the curved wall surfaces, the outer circumferential inner wall surface 10a and the inner circumferential inner wall surface 10b, is located below (on the cylinder block side) the lower deck 5.

In addition, reference numeral 12 in FIG. 1 denotes an ignition plug insertion hole into which an ignition plug is inserted. Also, reference numeral 13 in FIG. 1 denotes a fuel injection valve insertion hole into which a fuel injection valve is inserted.

Figure 2 is a cross-sectional view of a cylinder head 21 in a comparative example. For convenience, the same components as those in the above-described embodiment of the present invention are given the same reference numerals, and duplicated explanations will be omitted.

The comparative cylinder head 21 has substantially the same configuration as the cylinder head 1 of the embodiment of the present invention described above, but the cooling water inlet passage 22 of the water jacket 8 is bent in a crank shape.

As a result, in the cylinder head 21 of the comparative example, the cooling water flowing in from the cylinder block side collides with great force against the inner wall surface 23 of the cooling water inlet passage 22 at the crank-shaped bend.

If the cooling water inlet passage 22 has a crank-shaped bend, as in this comparative example, the flow lines of the cooling water will be disrupted at this portion, obstructing the flow of the cooling water and increasing the water flow resistance (passage resistance).

On the other hand, in the cylinder head 1 of the above-mentioned embodiment, the curved portion 10 of the cooling water inlet passage 9 is formed to have a predetermined curvature, and it is possible to form the angle of the wall surface of the cooling water inlet passage 9 at an inclined angle so as to follow the flow of the cooling water.

As a result, the cylinder head 1 can reduce passage resistance in the cooling water inlet passage 9.

The cylinder head 1 can increase the flow rate and flow velocity of the cooling water introduced into the water jacket 8 by reducing the passage resistance in the cooling water inlet passage 9.

In addition, the cylinder head 1 can improve cooling of the entire cylinder head 1 and the combustion chamber of the internal combustion engine by increasing the flow rate and flow speed of the cooling water.

The cooling water introduction passage 9 opens with the outer circumferential inner wall surface 10a and the inner circumferential inner wall surface 10b of the curved portion 10 inclined relative to the lower deck 5.

This allows the cooling water inlet passage 9 to reduce passage resistance and more smoothly introduce the cooling water from the cylinder block into the cylinder head 1.

The cooling water inlet passage 9 has an inner wall surface 11 formed so that it is smoothly continuous along the direction of the cooling water flow, which reduces the passage resistance in the cooling water inlet passage 9 and increases the flow rate and flow velocity of the cooling water introduced into the water jacket 8.

Figure 3 is a bottom view of the core 31 used when casting the cylinder head 1 of the internal combustion engine according to the present invention.

The cylinder head 1 of the above-mentioned embodiment is cast using a core 31 as shown in FIG. 3. The core 31 forms the water jacket 8 inside the cylinder head 1. The core 31 shown in FIG. 3 is used when casting a cylinder head when the present invention is applied to an in-line three-cylinder internal combustion engine. The recessed portion of the core 31 shown in FIG. 3 becomes a protruding portion in the cylinder head 1.

The core 31 has a main body 32 that forms the water jacket 8, a cooling water inlet passage forming portion 33 that forms the cooling water inlet passage 9, an extension portion 34 that is continuous with the cooling water inlet passage forming portion 33 and is located below the lower deck 5 of the cylinder head 1 (on the cylinder block side), and an outlet portion 35 that forms the outlet for the cooling water in the water jacket 8.

The extension 34 is formed such that the portion 34a that is continuous with the outer periphery (outside) of the curve of the cooling water introduction passage forming portion 33 protrudes further outward than the outer periphery of the curve of the cooling water introduction passage forming portion 33. This is because the cooling water introduction passage 9 formed by the cooling water introduction passage forming portion 33 opens into the lower deck 5 of the cylinder head 1 midway through the curve, and the portion 34a that is continuous with the outer periphery (outside) of the curve of the cooling water introduction passage forming portion 33 protrudes relatively outward.

By casting the cylinder head 1 using such a core 31, a water jacket 8 having a curved cooling water inlet passage 9 can be formed.

In other words, the core 31 has an extension 34 that protrudes toward the outer periphery of the curve relative to the cooling water inlet passage forming portion 33, making it possible to set a curved portion 10 for forming the cooling water inlet passage 9.

During casting, the portion of the cylinder head 1 that is formed by the extension 34 and protrudes from the lower deck 5 is removed, for example, by machining after casting.

1... cylinder head 4... upper deck 5... lower deck 6... camshaft support portion 8... water jacket 9... cooling water introduction passage 9a... opening 10... inner wall surface 10a... outer peripheral side inner wall surface 10b... inner peripheral side inner wall surface

Claims (5)

In a cylinder head of an internal combustion engine having a water jacket formed therein,
The water jacket has a cooling water inlet passage formed so as to conform to the shape of a bottom surface of a cavity that constitutes a part of the combustion chamber, and into which cooling water supplied from the outside flows from one end side of the water jacket.
The cooling water introduction passage has a curved portion curved at a predetermined curvature,
the curved portion constitutes one end of the cooling water introduction passage, opens into a lower deck of the cylinder head, and is curved so that the cooling water flowing along the curved portion is directed toward an upper portion of the cylinder head ,
a cylinder head for an internal combustion engine, characterized in that, when viewed in the cylinder row direction of the internal combustion engine, the cooling water inlet passage opens to the lower deck with an outer circumferential inner wall surface and an inner circumferential inner wall surface of the curved portion, which are part of the inner wall surface of the cooling water inlet passage, inclined with respect to the lower deck . The cylinder head of an internal combustion engine according to claim 1, characterized in that the cooling water introduction passage has an inner wall surface formed to be smoothly continuous along the direction in which the cooling water flows. The cylinder head of an internal combustion engine according to claim 1 or 2, characterized in that the cooling water introduction passage opens with a portion of its inner wall surface inclined relative to the lower deck. A cylinder head for an internal combustion engine as described in any one of claims 1 to 3, characterized in that the center of curvature of the curved portion is located below the lower deck. A method for manufacturing a cylinder head for an internal combustion engine having a water jacket formed therein, comprising the steps of:
The water jacket has a cooling water inlet passage formed so as to conform to the shape of a bottom surface of a cavity that constitutes a part of the combustion chamber, and into which cooling water supplied from the outside flows from one end side of the water jacket.
The cooling water introduction passage has a curved portion curved at a predetermined curvature,
the curved portion constitutes one end of the cooling water introduction passage, opens into a lower deck of the cylinder head, and is curved so that the cooling water flowing along the curved portion is directed toward an upper portion of the cylinder head,
the cooling water introduction passage opens into the lower deck in a state in which an outer circumferential side inner wall surface and an inner circumferential side inner wall surface of the curved portion, which are part of an inner wall surface of the cooling water introduction passage, are inclined with respect to the lower deck when viewed in a cylinder row direction of the internal combustion engine ,
The water jacket is formed using a core during casting,
the core has a cooling water introduction passage forming portion that forms the cooling water introduction passage, and an extension portion that is continuous with the cooling water introduction passage forming portion and forms a portion located below the lower deck,
a cooling water introduction passage forming portion having a curved outer periphery and a portion of the curved outer periphery that is continuous with the curved outer periphery of the cooling water introduction passage forming portion, the portion of the curved outer periphery being protruding further toward the outer periphery of the curved outer periphery than the portion of the curved outer periphery of the cooling water introduction passage forming portion.

Images