The disclosure of Japanese Patent Application No. 2007-165058 filed on Jun. 22, 2007 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
1. Field of the Invention
The invention relates to a structure for cooling an internal combustion engine.
2. Description of the Related Art
In a cylinder head of an internal combustion engine, the temperature of portions near exhaust valves and the temperature of portions near ignition plugs become considerably high. Therefore, these portions need to be cooled intensively. Accordingly, Japanese Examined Utility Model Application Publication No. 05-17373 (JP-UM-B-05-17373) describes the following structure of an internal combustion engine, which is applied to a multi-cylinder internal combustion engine in which multiple cylinders are arranged in line along the longitudinal axis of an engine body, intake valves and intake ports are arranged on one side of the longitudinal axis, and exhaust valves and exhaust ports are arranged on the other side of the longitudinal axis. In the structure described in JP-UM-B-05-17373, a water jacket formed within a cylinder block is partitioned into an intake port-side water jacket, which is on one side of the longitudinal axis, and an exhaust port-side water jacket, which is on the other side of the longitudinal axis. With the structure, a coolant in the exhaust port-side water jacket is introduced into a cylinder head at portions near exhaust valves and portions near ignition plugs, whereby these portions are cooled. Next, the coolant is caused to flow in portions near the intake valves and portions near the intake ports within the cylinder head in the lateral direction, that is, the direction perpendicular to the longitudinal axis. Then, the coolant flows into the intake port-side water jacket.
However, in the internal combustion engine described in JP-UM-B-05-17373, it is not possible to sufficiently cool portions near the exhaust ports where the temperature becomes considerably high.
The invention provides a structure with which portions near exhaust ports are cooled.
An aspect of the invention provides a structure for cooling an internal combustion engine which includes multiple cylinders that are arranged in line along the longitudinal axis of an engine body, and in which intakes ports are open on a first side wall face of a cylinder head, the first wall face being on one side of the longitudinal axis on which intake valves are arranged, and exhaust ports are open on a second wall face of the cylinder head, the second wall face being on the other side of the longitudinal axis on which exhaust valves are arranged. The structure includes a main passage which is formed within the engine body. Through the main passage, a coolant is introduced from the inside of a cylinder block into the inside of the cylinder head at portions near the exhaust valves, flows in portions near the intake valves and portions near the intake ports toward the first wall face in the lateral direction of the engine body, and then flows into the cylinder block. A portion of the coolant, which is introduced from the inside of the cylinder block into the inside of the cylinder head at the portions near the exhaust valves, is caused to flow in portions near the exhaust ports in the direction, which is opposite to the direction of a coolant flow along the main passage, toward the second side wall face in the lateral direction, and then flows along the second side wall face toward a coolant outlet from the engine body in the direction of the longitudinal axis.
A portion of the coolant, which is introduced into the portions near the exhaust valves, is caused to flow in the portions near the exhaust ports in the lateral direction and then flow toward the coolant outlet from the engine body in the direction of the longitudinal axis of the engine body. With this structure, it is possible to cool the portions near the exhaust ports sufficiently.
The foregoing and further features and advantages of the invention will become apparent from the following description of an example embodiment with reference to the accompanying drawings, wherein the same or corresponding portions will be denoted by the same reference numerals and wherein:
Hereafter, an embodiment of the invention will be described with reference to the accompanying drawings.
As shown in
In the internal combustion engine shown in
As shown in
The actual shapes of the water jackets are more complicated than the shapes of the water jackets WJ1 and WJ2 shown in
The water jacket WJ1 formed within the cylinder block 2 is partitioned into an intake port-side water jacket 20 and an exhaust port-side water jacket 21. The intake port-side water jacket 20 is positioned on one side of the longitudinal axis K-K of the engine body 1, and the exhaust port-side water jacket 21 is positioned on the other side of the longitudinal axis K-K. As shown in
As shown in
As described above, in the cylinder head 3 of the internal combustion engine, the temperature of portions near the exhaust valves 10 and the temperature of portions near the ignition plugs 7 become considerably high. Therefore, the portions near the exhaust valves 10 and the portions near the ignition plugs 7 need to be cooled intensively. Accordingly, a main coolant passage is formed within the engine body 1 so that the coolant flows in the following manner. As indicated by arrowed lines X2 in
The flow of the coolant along the main passage according to the embodiment of the invention will be described in more detail below. The coolant is introduced from the exhaust port-side water jacket 21 formed within the cylinder block 2 into the cylinder head 3, flows in portions between the paired exhaust valves 10, reaches the outer peripheral faces 17 of the cylindrical walls 16 that surround the ignition plug fitting holes 15, and then flows in the portions near the intake valves 8 and the portions near the intake ports 9 toward the side wall face 12 in the lateral direction. Because the coolant is caused to flow in the portions between the paired exhaust valves 10 toward the outer peripheral faces 17 of the cylindrical walls 16 that surround the ignition plugs 7, it is possible to sufficiently cool the portions near the exhaust valves 10 and the portions near the ignition plugs 7 where the temperature becomes considerably high.
In order to cause the coolant to flow in the portions between the paired exhaust valves 10 toward the outer peripheral walls 17 of the cylindrical walls 16 that surround the ignition plugs 7, each of the cylinders #1 to #4 is provided with a coolant passage 27. Each coolant passage 27 extends from the inside of the exhaust port-side water jacket 21 upward, curves toward the ignition plug 7, and then extends toward the outer peripheral wall 17 of the cylindrical wall 16. In the embodiment of the invention, the entire or most of the coolant that is supplied from the exhaust port-side water jacket 21 into the cylinder head 3 flows through the coolant passages 27.
In the embodiment of the invention, the coolant, which flows along the main passage, flows within the cylinder head 3, and then flows into the intake port-side water jacket 20. Next, as indicated by an arrowed line X3 in
As shown in
In order to cool portions near the exhaust ports 11, a portion of the coolant, which is introduced from the inside of the cylinder block 2 into the inside of the cylinder head 3 at the portions near the exhaust valves 10, is caused to flow in the portions near the exhaust ports 11 in the direction opposite to the direction of the coolant flow along the main passage indicated by the arrowed lines X2 (hereinafter, referred to as “main passage X2” where appropriate), toward the side wall face 13 in the lateral direction. Then, the coolant is caused to flow along the side wall face 13 toward the coolant outlet 28 in the direction of the longitudinal axis K-K of the engine body 1. That is, a portion of the coolant is diverted, on the outer peripheral faces 17 of the cylindrical walls 16, from the coolant that flows along the main passage X2, and then flows in the direction opposite to the direction of the coolant flow along the main passage X2.
In the embodiment of the invention, a flat upper water jacket 29 is formed above the exhaust ports 11 of the cylinders #1 to #4 and the exhaust gas gathering portion 14, and a flat lower water jacket 30 is formed below the exhaust ports 11 of the cylinders #1 to #4 and the exhaust gas gathering portion 14. A portion of the coolant, which is diverted from the coolant that flows along the main passage, flows within the upper water jacket 29 as indicated by arrowed lines Y1 toward the side wall face 13 in the lateral direction, and then flows along the side wall face 13 as indicated by an arrowed line Y2 toward the coolant outlet 28 in the direction of the longitudinal axis K-K of the engine body 1. At the same time, another portion of the coolant, which is diverted from the coolant that flows along the main passage, flows within the lower water jacket 30 as indicated by arrowed lines Z1 toward the side wall face 13 in the lateral direction, and then flows along the side wall face 13 as indicated by an arrowed line Z2 toward the coolant outlet 28 in the direction of the longitudinal axis K-K of the engine body 1.
That is, as indicated by the arrowed lines Y1 in
The upper water jacket 29 is connected to the coolant outlet 28 via an air-bleed passage 31, at an end portion on the coolant outlet 28 side in the direction of the longitudinal axis K-K of the engine body 1. The lower water jacket 30 is connected to the air-bleed passage 31, at an end portion on the coolant outlet 28 side in the direction of the longitudinal axis K-K of the engine body 1. Therefore, the lower water jacket 30 is also connected to the coolant outlet 28 via the air-bleed passage 31.
When the water jackets 29 and 30 are connected to the coolant outlet 28 via the air-bleed passage 31, as indicated by the arrowed lines Y2 and Z2 in
When the exhaust manifold integrated cylinder head 3 as shown in
The embodiment of the invention that has been described in the specification is to be considered in all respects as illustrative and not restrictive. The technical scope of the invention is defined by claims, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
Number | Date | Country | Kind |
---|---|---|---|
2007-165058 | Jun 2007 | JP | national |