Structure for cooling internal combustion engine

Abstract

Exhaust ports and an exhaust gas gathering portion are formed within a cylinder head. A main passage is formed within an 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 exhaust valves, flows in portions near intake valves and portions near intake ports toward a side wall face of the cylinder head in the lateral direction of the engine body, and then flows into the cylinder block. A portion of the coolant, which is introduced into the portions near the exhaust valves, is caused to flow in portions near the exhaust ports toward a side wall face of the cylinder head, and then flows along the side wall face toward a coolant outlet.

1 . A structure for cooling an internal combustion engine which includes multiple cylinders that are arranged in line along a 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, comprising:
 a main passage which is formed within the engine body, and through which a coolant is introduced from an inside of a cylinder block into an 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 a lateral direction of the engine body, and then flows into the cylinder block,   wherein 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 a direction, which is opposite to a 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 a direction of the longitudinal axis.   
   
   
       2 . The structure according to  claim 1 , wherein:
 a pair of the intake valves and a pair of the exhaust valves are arranged around each of ignition plugs;   the coolant, which flows along the main passage, flows from the inside of the cylinder block into the inside of the cylinder head, flows in portions between the paired exhaust valves, reaches outer peripheral faces of cylindrical walls that surround holes in which the ignition plugs are fined, and then flows in the portions near the intake valves and the portions near the intake ports toward the first side wall face in the lateral direction; and   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 diverted, on the outer peripheral faces of the cylindrical walls, from the coolant that flows along the main passage, and flows in the direction which is opposite to the direction of the coolant flow along the main passage.   
   
   
       3 . The structure according to  claim 1 , wherein:
 the exhaust ports of the respective cylinders meet each other within the cylinder head at an exhaust gas gathering portion that is shared by all the exhaust ports, and the exhaust gas gathering portion opens on the second side wall face;   a flat upper water jacket is formed above the exhaust ports of the cylinders and the exhaust gas gathering portion, and a flat lower water jacket is formed below the exhaust ports of the cylinders and the exhaust gas gathering portion;   a portion of the coolant, which flows in the direction opposite to the direction of the coolant flow along the main passage, flows within the upper water jacket toward the second side wall face in the lateral direction and then flows along the second side wall face toward the coolant outlet in the direction of the longitudinal axis; and   another portion of the coolant, which flows in the direction opposite to the direction of the coolant flow along the main passage, flows within the lower water jacket toward the second side wall face in the lateral direction and then flows along the second side wall face toward the coolant outlet in the direction of the longitudinal axis.   
   
   
       4 . The structure according to  claim 3 , further comprising:
 an air-bleed passage,   wherein the upper water jacket is connected to the coolant outlet via the air-bleed passage, at an end portion on a coolant outlet side in the direction of the longitudinal axis of the engine body.   
   
   
       5 . The structure according to  claim 3 , further comprising:
 an air-bleed passage,   wherein the lower water jacket is connected to the coolant outlet via the air-bleed passage at an end portion on a coolant outlet side in the direction of the longitudinal axis of the engine body.   
   
   
       6 . The structure according to  claim 1 , wherein:
 a water jacket formed within the 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; and   the coolant, which flows along the main passage, flows from the exhaust port-side water jacket, flows within the cylinder head, and flows toward the intake port-side water jacket.   
   
   
       7 . The structure according to  claim 1 , wherein:
 a coolant inlet to the engine body is formed at an end portion of the exhaust port-side water jacket in the direction of the longitudinal axis; and   the coolant outlet is formed in the cylinder head at a corner portion that is diagonally opposite to the coolant inlet when the engine body is viewed from above.   
   
   
       8 . The structure according to  claim 1 , further comprising:
 a coolant inlet,   wherein the coolant is supplied through the coolant inlet, and   wherein the coolant outlet is at a position that is higher than the coolant inlet.   
   
   
       9 . A structure for cooling an internal combustion engine that includes multiple cylinders which are arranged in line along a longitudinal axis of an engine body, intake ports that open at a portion of a cylinder head, which is on one side of the longitudinal axis, and exhaust ports that open at another portion of the cylinder head, which is on the other side of the longitudinal axis, comprising:
 an exhaust port-side water jacket that is formed in an exhaust port-side portion of a cylinder block;   an intake port-side water jacket that is formed in an intake port-side portion of the cylinder block;   a coolant inlet;   a main passage through which a coolant, which is introduced into the exhaust port-side water jacket through the coolant inlet, flows into the cylinder head at portions near exhaust valves, flows in portions near the intake ports, and then flows into the intake port-side water jacket formed within the cylinder block;   a passage through which the coolant, which is introduced from the exhaust port-side water jacket into the cylinder head at the portions near the exhaust valves, flows in portions near the exhaust ports in a direction opposite to a direction of a coolant flow along the main passage, and then flows in a direction of the longitudinal axis; and   a coolant outlet through which the coolant flows out of the engine body.   
   
   
       10 . The structure according to  claim 9 , wherein:
 ignition plugs are provided in the cylinder head;   a pair of the intake ports and a pair of the exhaust ports are formed around each ignition plug;   the main passage is formed so that the coolant flows from an inside of the cylinder block into an inside of the cylinder head, flows in portions between the paired exhaust ports within the cylinder head, reaches outer peripheral faces of cylindrical walls that surround holes in which the ignition plugs are fitted, and flows in portions near intake valves and the portions near the intake ports toward the intake port-side water jacket; and   the passage is formed so that a portion of the coolant, which is introduced from the exhaust port-side water jacket into the cylinder head at the portions near the exhaust valves, is diverted, on the outer peripheral faces of the cylindrical walls, from the coolant that flows along the main passage, and flows in the direction opposite t 6  the direction of the coolant flow along the main passage.   
   
   
       11 . The structure according to  claim 9 , further comprising:
 an exhaust gas gathering portion that is formed within the cylinder head, and that is shared by the exhaust ports of all the cylinders;   an upper water jacket that is formed above the exhaust ports of the cylinders and the exhaust gas gathering portion;   a lower water jacket that is formed below the exhaust ports of the cylinders and the exhaust gas gathering portion;   a passage through which a portion of the coolant, which flows in the direction opposite to the direction of the coolant flow along the main passage, flows within the upper water jacket toward the coolant outlet in the direction of the longitudinal axis; and   a passage through which another portion of the coolant, which flows in the direction opposite to the direction of the coolant flow along the main passage, flows within the lower water jacket toward the coolant outlet in the direction of the longitudinal axis.   
   
   
       12 . The structure according to  claim 11 , further comprising:
 an air-bleed passage,   wherein the upper water jacket is connected to the coolant outlet via the air-bleed passage, at an end portion on a coolant outlet side in the direction of the longitudinal axis of the engine body.   
   
   
       13 . The structure according to  claim 11 , further comprising:
 an air-bleed passage,   wherein the lower water jacket is connected to the coolant outlet via the air-bleed passage, at an end portion on a coolant outlet side in the direction of the longitudinal axis of the engine body.   
   
   
       14 . The structure according to  claim 9 , wherein:
 the coolant inlet is formed at an end portion of the exhaust port-side water jacket in the direction of the longitudinal axis; and   the coolant outlet is formed at a corner portion of the cylinder head, which is diagonally opposite to the coolant inlet, when the engine body is viewed from above.   
   
   
       15 . The structure according to  claim 9 , wherein the coolant outlet is at a position that is higher than the coolant inlet.