Patent attributes
In a cylinder block of an internal combustion engine, a water jacket in which coolant is circulated is formed around cylinder bores. In the cylinder block, an introduction passage, through which the coolant is introduced from the outside of the water jacket to the inside of the water jacket, is formed. A spacer, which extends along at least a portion of the periphery of the cylinder bores is provided in the water jacket. The spacer is disposed such that the inner wall surface of the spacer contacts the outer wall surfaces of the cylinder bores in an opening-side area of the cylinder block, where an opening of the introduction passage is formed, and the inner wall surface of the spacer does not contact the outer wall surfaces of the cylinder bores in an opposite opening-side area opposite to the opening-side area with respect to the cylinder bores.
