Water-cooled internal combustion engine

Abstract

A water-cooled internal combustion engine has a cylinder head 21 provided with a cylinder head water jacket Jh through which cooling water flows. The cylinder head water jacket Jh includes a combustion chamber water jacket 70 surrounding combustion chambers 26 and an exhaust passage water jacket 71 around an exhaust manifold passage 38. The exhaust gas discharged from the combustion chambers 26 through exhaust ports 28 flows through the exhaust manifold passage. The exhaust passage water jacket 71 is divided into an upstream water jacket 72a and a downstream water jacket 72b by a partition wall 75. The cooling water flows from both the upstream water jacket 72a and the downstream water jacket 72a into the combustion chamber water jacket 70. Equality in temperature between a combustion chamber wall and an exhaust passage wall is improved and the cylinder head 21 is heated in a uniform temperature distribution.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevation of an outboard motor provided with a water-cooled internal combustion engine in a preferred embodiment of the present invention taken from the right-hand side of the outboard motor;

FIG. 2 is a view taken in the direction of the arrow II in FIG. 1 showing an essential part of a cylinder block included in the water-cooled internal combustion engine;

FIG. 3 is a view taken in the direction of the arrow III in FIG. 1 showing an essential part of a cylinder head included in the water-cooled internal combustion engine;

FIG. 4 is a sectional view taken on the line IV-IV in FIG. 3;

FIG. 5 is a sectional view taken on the line V-V in FIG. 3;

FIG. 6 is a schematic sectional view taken on the line VI-VI in FIG. 9;

FIG. 7 is a schematic sectional view taken on the line VII-VII in FIG. 3;

FIG. 8A is a view taken in the direction of the arrow VIIIa in FIG. 2;

FIG. 8B is a view taken on the line VIIIb-IIIb in FIG. 2;

FIG. 8C is a view taken in the direction of the arrow VIIIc in FIG. 2;

FIG. 8D is a sectional view taken on the line d-d in FIG. 8C;

FIG. 9 is a view taken in the direction of the arrow IX in FIG. 3;

FIG. 10 is a sectional view taken on the line X-X in FIG. 9, in which a cover is held in place;

FIG. 11A is a view taken in the direction of the arrow XI in FIG. 3;

FIG. 11B is a sectional view taken on the line b-b in FIG. 11A;

FIG. 11C is a view taken in the direction of the arrow c in FIG. 11A; and

FIG. 12 is a typical view of a cooling system included in the water-cooled internal combustion engine shown in FIG. 1.

Claims

1. A water-cooled internal combustion engine comprising: a cylinder block provided with a plurality of cylinders aligned in a row; anda cylinder head defining combustion chambers respectively corresponding to the cylinders, and provided with an exhaust manifold passage into which exhaust gas discharged from the combustion chambers through exhaust ports flows, and a cylinder head water jacket for cooling water including a combustion chamber water jacket surrounding the combustion chambers and an exhaust passage water jacket around the exhaust manifold passage;wherein the exhaust passage water jacket is divided into an upstream water jacket and a downstream water jacket by a flow restricting means, and a part on the upstream side of the flow restricting means of the upstream water jacket is connected to the combustion chamber water jacket to make the cooling water flow from the upstream water jacket into the combustion chamber water jacket.

2. The water-cooled internal combustion engine according to claim 1, wherein the downstream water jacket is connected to the combustion chamber water jacket so that the cooling water flowing through the downstream water jacket flows from a part on the downstream side of the flow restricting means of the downstream water jacket into the combustion chamber water jacket.

3. The water-cooled internal combustion engine according to claim 1, wherein the cylinder head is provided with a connecting passages through which part of the cooling water flowing in the upstream water jacket flows into the downstream water jacket.

4. The water-cooled internal combustion engine according to claim 1, wherein the cylinder head is provided with a bypass water jacket through which part of the cooling water flowing in the upstream water jacket flows into the downstream water jacket, the bypass water jacket serving also as the exhaust passage water jacket.

5. The water-cooled internal combustion engine according to claim 3, wherein the exhaust passage water jacket has an inlet, the upstream water jacket has an inlet, and those inlets coincide with each other.

6. The water-cooled internal combustion engine according to claim 1, wherein an inlet of the cylinder head water jacket serves as inlets of the exhaust passage water jacket, and an outlet of the cylinder head water jacket serves also as an outlet of the combustion chamber water jacket.

7. A water-cooled internal combustion engine comprising: a cylinder block provided with a plurality of cylinders; anda cylinder head defining combustion chambers respectively corresponding to the cylinders, the cylinder head having an exhaust manifold passage into which exhaust gas discharged from the combustion chambers flows, and a cylinder head water jacket including an exhaust passage water jacket around the exhaust manifold passage, the cylinder head being formed by casting in a mold;wherein the exhaust passage water jacket and the exhaust manifold passage are ones formed by cores, respectively, in the mold, the exhaust passage water jacket includes a first exhaust passage water jacket farther from the combustion chambers and a second exhaust passage water jacket nearer to the combustion chambers, the first and the second exhaust passage water jacket extend on opposite sides, with respect to a direction parallel to axes of the cylinders, of the exhaust manifold passage, respectively, the cylinder head is provided with an outlet of the exhaust manifold passage and a through hole spaced part from the outlet of the exhaust manifold passage and opening into the exhaust manifold passage, and the through hole is formed between the first exhaust passage water jacket and the second exhaust passage water jacket.

8. The water-cooled internal combustion engine according to claim 7, wherein the first exhaust passage water jacket farther from the combustion chambers and the second exhaust passage water jacket nearer to the combustion chambers do not overlap the exhaust manifold passage and the through hole entirely as viewed from a position farther from a center plane including axes of the cylinders than the exhaust manifold passage.

9. The water-cooled internal combustion engine according to claim 7, wherein the outlet of the exhaust manifold passage and the through hole are at opposite end parts of the exhaust manifold passage with respect to a direction parallel to the row of the cylinders, respectively.

10. The water-cooled internal combustion engine according to claim 7, wherein the outlet of the exhaust manifold passage opens in a joining surface of the cylinder head to be joined to the cylinder block, and the through hole extends through the cylinder head parallel with the joining surface.

11. The water-cooled internal combustion engine according to claim 1, wherein the through hole holds therein any one of measuring devices including an exhaust gas measuring device for measuring properties of the exhaust gas or any one of tubular members including a sampling tube for sampling the exhaust gas, a tube opening into the atmosphere and a secondary air supply tube for supplying secondary air for exhaust emission control.