Abstract: An internal combustion engine wherein an exhaust pipe is connected to an exhaust outlet opening of an integral exhaust manifold-type cylinder head and a sensor having a sensing part liable to be damaged by deposition of moisture is arranged at an exhaust inlet part of the exhaust pipe. Exhaust ports of a cylinder positioned at the center are formed so that the sensing part of the sensor is not contained in the extended tubular shaped surfaces of the openings of the exhaust ports of the cylinder positioned at the center to the exhaust merging portion.

Abstract: A core portion (47) that is used to hold an upper water jacket-forming core (45) and a lower water jacket-forming core (46) with a predetermined distance maintained therebetween includes holding core portions (48) and distance maintaining core portions (50). The upper water jacket-forming core (45) and the lower water jacket-forming core (46) are split from each other at the holding core portions (48). Communication passages that provide communication between an upper water jacket and a lower water jacket are formed by the distance maintaining core portions (50).

Abstract: In an internal combustion engine, one end of a cylinder head (1) in a longitudinal direction is provided with a cooling water inflow port (19) leading to the inside of the cylinder head (1), while the other end of the cylinder head (1) in the longitudinal direction is provided with an outflow port (20) of main cooling water flow (X) flowing through the center inside the cylinder head (1). Further, an outflow port (21) of sub cooling water flows (Y) branched from the main cooling water flow (X) and flowing around the merged part of the exhaust port (5) is provided. An adapter (23) communicated with the main cooling water outlet (20) and sub cooling water outlet (21) and combining these outflow ports (20, 21) into a single cooling water outlet (22) is fixed to the outer wall surface of the cylinder head (1).

Abstract: A cylinder head in which a partition wall for separating exhaust ports of adjoining cylinders extends from between these adjoining cylinders to an exhaust merging portion and the partition wall is formed with a head bolt insertion hole inside it, an oil passage is formed in the partition wall between the front end of the partition wall facing the exhaust merging portion and the head bolt insertion hole, and a heat insulating layer is formed inside the partition wall between the front end of the partition wall and the oil passage.

Abstract: An in-line four-cylinder internal combustion engine wherein exhaust ports (8, 9) of a pair of cylinders positioned at the center are connected to a single merged exhaust port (11) and this merged exhaust port (11) is connected through a first exhaust pipe (19) to a catalytic converter (18). On the other hand, exhaust ports (7, 10) of pairs of cylinders positioned at the two ends are connected through a second exhaust pipe (21) to a catalytic converter (18). A length of the first exhaust pipe (19) from the merged exhaust port (11) to the catalytic converter (18) is made shorter than the length of the second exhaust pipe (21) from the exhaust ports (7, 10) to the catalytic converter (18).

Abstract: An internal combustion engine wherein an exhaust pipe is connected to an exhaust outlet opening of an integral exhaust manifold-type cylinder head and a sensor having a sensing part liable to be damaged by deposition of moisture is arranged at an exhaust inlet part of the exhaust pipe. Exhaust ports of a cylinder positioned at the center are formed so that the sensing part of the sensor not contained in the extended tubular shaped surfaces of the openings of the exhaust ports of the cylinder positioned at the center to the exhaust merging portion.

Abstract: A core portion (47) that is used to hold an upper water jacket-forming core (45) and a lower water jacket-forming core (46) with a predetermined distance maintained therebetween includes holding core portions (48) and distance maintaining core portions (50). The upper water jacket-forming core (45) and the lower water jacket-forming core (46) are split from each other at the holding core portions (48). Communication passages that provide communication between an upper water jacket and a lower water jacket are formed by the distance maintaining core portions (50).

Abstract: In an internal combustion engine, one end of a cylinder head (1) in a longitudinal direction is provided with a cooling water inflow port (19) leading to the inside of the cylinder head (1), while the other end of the cylinder head (1) in the longitudinal direction is provided with an outflow port (20) of main cooling water flow (X) flowing through the center inside the cylinder head (1). Further, an outflow port (21) of sub cooling water flows (Y) branched from the main cooling water flow (X) and flowing around the merged part of the exhaust port (5) is provided. An adapter (23) communicated with the main cooling water outlet (20) and sub cooling water outlet (21) and combining these outflow ports (20, 21) into a single cooling water outlet (22) is fixed to the outer wall surface of the cylinder head (1).

Abstract: Exhaust ports (8 and 9) of paired middle cylinders (#2 and #3) in which respective power strokes take place with one intervening power stroke therebetween are joined together in a cylinder head (1) to form a joint exhaust port (11). Exhaust ports (7 and 10) of paired end cylinders (#1 and #4) in which respective power strokes take place with one intervening power stroke therebetween extend from the respective cylinders (#1 and #4) toward the joint exhaust port (11). Then, on the respective sides of the joint exhaust port (11), the exhaust ports (7 and 10) extend along the joint exhaust port (11) to a side wall face (5) of the cylinder head (1) while the exhaust ports (7 and 10) and the joint exhaust port (11) are separated from each other by respective thin walls (12 and 13).

Abstract: A cylinder head in which a partition wall for separating exhaust ports of adjoining cylinders extends from between these adjoining cylinders to an exhaust merging portion and the partition wall is formed with a head bolt insertion hole inside it, an oil passage is formed in the partition wall between the front end of the partition wall facing the exhaust merging portion and the head bolt insertion hole, and a heat insulating layer is formed inside the partition wall between the front end of the partition wall and the oil passage.