JP2001289116A - Cooling water passage structure for cylinder head and method for manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling water passage structure for a cylinder head, capable of improving the cooling efficiency of an on-vehicle engine with a plurality of cylinders arranged in series at a wall portion between a suction port and an exhaust port. SOLUTION: The cooling water passage for the cylinder head 1 has two parallel passages, a suction side passage 2 extending through the periphery of the suction port 5 to the longitudinal direction and an exhaust side passage 3 extending through the periphery of the exhaust port 6 to the longitudinal direction. A center passage 4 set between the suction port 5 and the exhaust port 6 is separated into upper and lower stages, an upper center passage 4a being communicated with the exhaust side passage 3 and a lower center passage 4b being communicated with the suction side passage 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling water passage structure of a cylinder head used in a vehicle-mounted engine in which a plurality of cylinders are arranged in series, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, as disclosed, for example, in Japanese Utility Model Laid-Open Publication No. 7-35741, a cooling water passage provided in a cylinder head is separately formed into an intake passage and an exhaust passage. Have been. As described above, when the cooling water passage is separated into the intake side passage and the exhaust side passage, and the cooling water is configured to flow in parallel, compared with the case of the series passage in which the cooling water passage is provided continuously, Since the distance for each passage is shortened, the pressure loss is reduced, and there is an advantage that the cooling water pump to be used can be downsized. A cylinder head having a cooling water passage having such a structure is disclosed in, for example, Japanese Patent Application Laid-Open No. 9-203346 and Japanese Utility Model Application Laid-Open No. 7-3574.
No. 1 publication.

[0003] The cooling water passage formed in the cylinder head is set so as to cool particularly around the port. FIG. 15 is a sectional view showing a cooling water passage structure around a general port. As shown in the figure, in many cases, the cooling water passage of the cylinder head 50 includes an intake side passage 53 passing around the intake port 51, an exhaust side passage 54 passing around the exhaust port 52, and a connection between the intake port 51 and the exhaust port 52. It has three passages with a central passage 55 passing through an intermediate portion (above the center of the combustion chamber). The central passage 55 passing between the ports is generally formed in a substantially inverted triangular shape as shown in FIG.
Then, when a passage structure in which the cooling water flows in parallel with being separated into the intake side passage 53 and the exhaust side passage 54 is adopted, it is dependent (communicated) on one of the intake side passage 53 and the exhaust side passage 54.

[0004]

By the way, when cooling the cylinder head 50, the vicinity 56 of the lower end between the ports where the intake port 51 and the exhaust port 52 are closest to each other.
Is a place that is easily affected by thermal fatigue and cracks due to thermal fatigue because of its thin wall thickness, and is therefore a place that needs the most cooling. However, in the case of the above-described cooling water passage structure, since the cross-sectional shape of the central passage 55 is set to a substantially inverted triangle, the cooling water flow does not depend on the flow rate but on the upper U side and the lower L side. Imbalance occurs. That is, while the upper side U flows easily, the lower side L does not easily flow. For this reason, there is a problem in that the flow of the cooling water in the passage passing through the vicinity 56 at the lower end between the intake port 51 and the exhaust port 52 that requires the most cooling is stagnant or slow, and it is difficult to obtain sufficient cooling efficiency.

The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide an in-vehicle engine in which a plurality of cylinders are arranged in series. It is an object of the present invention to provide a cylinder head cooling water passage structure and a manufacturing method which are effective in increasing the cooling efficiency of the wall between the cylinder heads.

[0006] In order to achieve the above object, the present invention has a configuration as described in the claims. Therefore, according to the first and second aspects of the invention, the central passage passing between the intake port and the exhaust port is formed in two stages, upper and lower, so that the upper central passage and the lower central passage are formed. Imbalance is unlikely to occur in the flow amount regardless of the flow amount. For this reason, if the same amount of cooling water as that of the central passage constituted by the above-described conventional single passage is made to flow through the upper and lower central passages, the flow rate of the cooling water flowing through the lower central passage is reduced by the conventional central passage. It is possible to increase the amount compared to the amount flowing on the lower side of the passage. As a result, the cooling efficiency of the lower end between the ports in the cylinder head can be improved. In addition, since the central passage is divided into upper and lower stages, the partition wall helps to improve the rigidity of the cylinder head.

Also, as in the invention described in claim 2,
When one of the central passages is configured to communicate with the intake-side passage and the other central passage is communicated with the exhaust-side passage, the core used to form the cooling water passage when the cylinder head is manufactured by casting. Only two tubes are required, and the handling becomes easy. Further, when the upper and lower central passages are provided independently of each other on the intake side passage and the exhaust side passage as in the invention described in claim 3, the cooling water is appropriately distributed to each passage. The options for setting the cross-sectional area so as to satisfy the requirements can be expanded.

Further, according to the invention described in claim 4,
A method for manufacturing a cylinder head having a cooling water passage capable of increasing the cooling efficiency of the lower end portion between the ports can be provided. According to this manufacturing method, a stepped wall can be set between the opposed surfaces of the intake-side passage forming core and the exhaust-side passage forming core, that is, between the intake-side passage and the exhaust-side passage. . In other words, the stepped wall has a structure in which two vertical ribs spaced apart from each other at a predetermined interval are arranged between the intake port and the exhaust port. It is possible to improve the rigidity of the cylinder head in the vertical direction without particularly reducing the size.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. In the present embodiment, a plurality of cylinders are arranged in series, and one cylinder is provided with two intake valves and two exhaust valves.
The present invention is applied to a valve DI (direct injection) engine, and an outline of a cooling water passage structure according to the present embodiment will be described based on a schematic diagram shown in FIG. However, the schematic diagram shows one cylinder (combustion chamber).

A cooling water passage formed in the cylinder head 1 includes an intake passage 2 extending longitudinally along the intake port 5, an exhaust passage 3 extending longitudinally along the exhaust port 6, and an intake port 5. And an exhaust port 6, that is, a central passage 4 passing above a center of a cylinder 7 (hereinafter also referred to as a combustion chamber). And the central passage 4
Is divided into two upper and lower passages. One (lower) central passage 4 b is communicated with the intake passage 2, and the other (upper) central passage 4 a is communicated with the exhaust passage 3. Thus, the cooling water passage of the cylinder head 1 is separated into two independent passages in parallel with the intake passage 2 having the lower central passage 4b and the exhaust passage 3 having the upper central passage 4a. . Further, the respective passage entrance areas are set such that the amounts of cooling water flowing through the intake side passage 2 and the exhaust side passage 3 are respectively distributed appropriately.

The cooling water sent from a water pump (not shown) is divided into the intake side passage 2 and the exhaust side passage 3 of the cylinder head 1 through the cooling water passage of the cylinder block. After flowing out of the passage 3, they are merged and sent to the radiator. By configuring as described above, even if the cross-sectional area at a certain location is reduced, the increase in pressure loss accompanying the cross-sectional area is smaller than in the case of a series passage in which the intake passage and the exhaust passage are continuous. It does not become large, and it becomes possible to use a small water pump for cooling water supply.

By the way, in a diesel 4-valve DI engine in which cylinders are arranged in series, when an intake valve 11 and an exhaust valve 12 are arranged as shown in FIG.
The wall thickness of the valve sandwiching portion 13 sandwiched between 1 and 12 is as follows.
It is difficult to set thick. And the valve gap 1
Since No. 3 is also the most thermally affected portion, thermal fatigue cracks are liable to occur in the valve sandwiching portion 13. Therefore, it is desirable that the valve sandwiching portion 13 be strongly cooled by cooling water.

Therefore, in this embodiment, in order to meet such a demand, as described above, the cooling water passage of the cylinder head 1 is provided with the intake passage 2 having the central passage 4a and the exhaust passage having the central passage 4b. It is divided into two independent passages parallel to the side passage 3 and the central passage 4 is formed vertically. Hereinafter, a specific structure of the cooling water passage will be described with reference to FIGS. FIG. 2 is a plan view of the cylinder head as viewed from above, and FIG. 3 is a plan view of the same cylinder head as viewed from below. 4 to 6 are sectional views showing the cooling water passage, and FIG.
5 is a sectional view taken along line BB of FIGS. 1 and 2, and FIG. 6 is a sectional view taken along line CC of FIGS. 1 and 2. FIG. 7 is a plan view of the cylinder head gasket.

The cooling water flows from the passage on the side of the cylinder block (not shown) through the flow holes 21 and 22 of the gasket 8 shown in FIG.
2 and flows into the intake side passage 2 and the exhaust side passage 3 of the cylinder head 1 in parallel. Flow holes 2 on intake side and exhaust side
1 and 22 are set so that the cooling water is distributed to the intake passage 2 and the exhaust passage 3 in an appropriate amount.

The intake side passage 2 passing through the outside of the intake port 5 in the longitudinal direction and the intake side (lower side) central passage 4b
As shown in FIGS. 4 and 5, a portion corresponding to the intake port 5 and the adjacent intake ports 5 are separated from each other as shown in FIGS.
Are joined as shown in FIG.

On the other hand, the exhaust-side passage 3 extending outside the exhaust port 6 is connected to the exhaust port 6 with respect to one cylinder 7.
And between the adjacent exhaust ports 6
As shown in FIGS. 4 and 5, it is divided into two upper and lower passages with the exhaust port 6 interposed therebetween. In addition, the central passage 4a on the exhaust side (upper side) is set between the exhaust port 6 and the intake port 5 at a portion corresponding to the exhaust port 6, as shown in FIG. As shown in FIG. 6, it is joined to the upper passage of the exhaust passage 3. Further, the exhaust-side passage 3 and the central passage 4a merge with the exhaust port 6 of the adjacent cylinder 7 as shown in FIG. 6 (one passage).
Have been.

The central passage 4b on the intake side and the central passage 4a on the exhaust side are set so as to overlap each other as shown in FIG. 4, so that the central passage 4b on the intake side and the exhaust passage As a result, a partition wall 9 that defines the central passage 4a on the side connects the walls on the intake port 5 side and the exhaust port 6 side. The intake-side central passage 4b and the exhaust-side central passage 4a have substantially the same sectional area.

As described above, in the present embodiment, the central passage 4 set between the intake port 5 and the exhaust port 6 is divided into upper and lower parts, so that the upper central passage 4a
It is difficult for the flow rate of the cooling water to be unbalanced between the cooling water flow and the lower central passage 4b. Therefore, if it is assumed that the same amount of cooling water as that of the above-described conventional single passage 55 is formed in the upper and lower central passages 4a and 4b, the amount of cooling water flowing through the lower central passage 4b Can be increased as compared with the conventional amount flowing on the lower side of the central passage 55. For this reason, it is possible to increase the cooling efficiency of the lower end portion between the ports in the cylinder head 1, that is, the valve interposition portion 13 interposed between the intake valve 11 and the exhaust valve 12 shown in FIG. This is effective in preventing thermal fatigue failure.

In this case, when it is desired to increase the flow rate of the cooling water flowing through the central passages 4a and 4b, the sectional areas of the intake side passage 2 and the exhaust side passage 3 flowing outside the port are respectively determined by the sectional areas of the central passages 4a and 4b. It becomes possible by setting it smaller. With such a setting, the pressure loss increases, but the increase is formed by dividing the cooling water passage into the intake passage 2 and the exhaust passage 3 as in the present embodiment. With the configuration in which the cooling water flows in parallel, it is not necessary to be so large as compared with a serial passage structure in which the passages on the intake side and the exhaust side are continuous.

Further, in the present embodiment, by dividing the central passage 4 into upper and lower portions, the port walls are connected by the plate-shaped partition wall 9 between the upper and lower passages 4a and 4b, so that the rigidity between the ports is reduced. It is possible to increase.

The cylinder head 1 having the cooling water passage structure configured as described above is manufactured by setting a core in a mold formed in a predetermined shape and then pouring a molten metal into the mold. That is, the cylinder head 1 is manufactured by casting.
It is manufactured using a core as shown in FIGS.

FIG. 8 is a perspective view showing an intake-side passage forming core, FIG. 9 is a perspective view showing an exhaust-side passage forming core, and FIG.
FIG. 11 is a perspective view of a state in which an intake-side passage forming core and an exhaust-side passage forming core are combined, and FIG. 11 is a schematic front view of the same. FIG. 12 is a perspective view of a state cut from a part corresponding to the cross-sectional view of FIG. 3, FIG. 13 is a perspective view showing a state of cut from a part corresponding to the cross-sectional view of FIG. 4, and FIG. It is a perspective view showing the state where it cut | disconnected from the site | part corresponding to a figure.

As shown in FIG. 8, the intake-side passage forming core 31 includes an intake-side passage forming portion 31a and a central passage forming portion 31.
b, and is formed in a substantially L-shaped cross section. On the other hand, as shown in FIG. 9, the exhaust-side passage forming core 32 includes an exhaust-side passage forming portion 32a and a central passage forming portion 32b, and is formed to have a substantially L-shaped cross section. As shown in FIGS. 10 and 14, the cores 31 and 32 formed as described above are mutually central passage forming portions 31b and 32b.
Are set in a mold in a state where they are arranged at predetermined intervals so as to overlap in the vertical direction.

Accordingly, a substantially N-shaped facing gap S is formed between the facing surfaces of the intake-side passage forming core 31 and the exhaust-side passage forming core 32 arranged as described above. Therefore,
A stepped wall is set between the intake side passage 2 and the exhaust side passage 3 in the cylinder head 1 after casting. In other words, the stepped wall has a structure in which two vertical ribs spaced apart from each other with a predetermined interval are arranged between the intake port 5 and the exhaust port 6. Therefore, the rigidity of the cylinder head 1 in the vertical direction can be improved without particularly reducing the cross-sectional area of the cooling water passage by such a rib structure.

It should be noted that the present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist of the present invention. For example, the central passage 4a,
4b may be set in a form completely independent of the intake side passage 2 and the exhaust side passage 3. That is, the cooling water passage
Intake-side passage 2, exhaust-side passage 3, and upper and lower central passages 4a, 4
It may be a four-part structure parallel to b. When such a configuration is adopted, options for setting the cross-sectional area so that the cooling water is distributed to each passage in an appropriate amount can be expanded. Instead of flowing through the cooling holes 21 and 22 provided in the gasket 8, pipes may be used for inflow of the cooling water into the intake side passage 2 and the exhaust side passage 3.

[0026]

As described in detail above, according to the present invention,
In a vehicle-mounted engine in which a plurality of cylinders are arranged in series, it is possible to efficiently perform cooling particularly on the wall between the intake port and the exhaust port.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating an outline of a cooling water passage structure according to the present embodiment.

FIG. 2 is a plan view of the cylinder head as viewed from above.

FIG. 3 is a plan view of the cylinder head as viewed from a lower surface side.

FIG. 4 is a sectional view taken along line AA of FIGS. 1 and 2;

FIG. 5 is a sectional view taken along line BB of FIGS. 1 and 2;

FIG. 6 is a sectional view taken along line CC of FIGS. 1 and 2;

FIG. 7 is a plan view of a cylinder head gasket.

FIG. 8 is a perspective view showing an intake-side passage forming core.

FIG. 9 is a perspective view showing an exhaust-side passage forming core.

FIG. 10 is a perspective view showing a state where an intake-side passage forming core and an exhaust-side passage forming core are combined.

FIG. 11 is a schematic front view of the same.

FIG. 12 is a perspective view of a state cut from a portion corresponding to the cross-sectional view of FIG. 3;

FIG. 13 is a perspective view showing a state cut from a portion corresponding to the cross-sectional view of FIG. 4;

FIG. 14 is a perspective view showing a state cut from a portion corresponding to the cross-sectional view of FIG. 5;

FIG. 15 is a cross-sectional view showing a conventional general cooling water passage structure around a port.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Cylinder head 2 ... Intake side passage 3 ... Exhaust side passage 4 ... Central passage 4a ... Exhaust side central passage 4b ... Intake side central passage 5 ... Intake port 6 ... Exhaust port

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) F02F 1/38 F02F 1/38 B

Claims (4)

[Claims] 1. A cooling water passage structure for a cylinder head for an engine in which a plurality of cylinders are arranged in series, wherein the cooling water passage structure extends longitudinally around an intake port and passes around an exhaust port. And a central passage passing between the intake port and the exhaust port. The central passage is formed in two stages, upper and lower, for cooling the cylinder head. Water passage structure. 2. The cooling water passage structure for a cylinder head according to claim 1, wherein one of the upper and lower central passages is communicated with an intake passage, and the other central passage is an exhaust passage. A cooling water passage structure for a cylinder head. 3. The cooling water passage structure for a cylinder head according to claim 1, wherein the upper and lower central passages are provided independently of the intake-side passage and the exhaust-side passage, respectively. Characteristic cooling water passage structure of cylinder head. 4. When a cylinder head of an engine in which a plurality of cylinders are arranged in series is cast using a mold having a predetermined shape, the cylinder head extends in a longitudinal direction around an intake port, and is formed between an intake port and an exhaust port. An intake-side passage-forming core formed in a substantially L-shaped cross-section for forming an intake-side passage having a central passage passing therethrough, and a longitudinally extending through an exhaust port periphery; and An exhaust-side passage forming core having a substantially L-shaped cross section for forming an exhaust-side passage having a central passage passing between the exhaust port and the exhaust-side passage forming core; And injecting a molten metal into the mold.