Seal structure for internal combustion engine

A seal structure for an internal combustion engine at a junction of three members including an engine main body section including a cylinder block and a cylinder head;

• a chain casing assembled onto one end surface of a periphery of the engine main body section via a seal member;
• and at least one cover member assembled via another seal member so as to extend on upper surface sides or lower surface sides of both of the engine main body section and the chain casing, the seal structure comprising:
• a cover side seal member arranged in a closed loop shape, which extends on upper surface sides or lower surface sides of both of the engine main body section and the chain casing, and which is pressed and held against the at least one cover member;
• a casing side seal member arranged at a left or right end section of one end surface of the engine main body section onto which the chain casing is attached, and which is pressed and held against the chain casing;
• a receiving concavity formed to extend on a surface where the chain casing meets the engine main body section and another surface where the chain casing meets the at least one cover member, the receiving concavity including a receiving surface parallel to the another surface where the chain casing meets the at least one cover member;
• and
• a connection block section formed integrally on one end section of the casing side seal member in an elongate direction of the casing side seal member, and fitted into and retained by the receiving concavity, and which is projected more toward a side of the at least one cover member than the another surface where the chain casing meets the at least one cover member in a free state, an end surface of the connection block section opposing against the at least one cover member so as to provide a flat abutting surface, and, in a state in which the three members of the engine main body section, the chain casing, and the at least one cover member are joined and assembled together, the cover side seal member is contacted on the abutting surface of the connection block section under pressure to interconnect both of the cover side and casing side seal members.