Patent ID: 7614373

Claim:
An oil passage construction for an internal combustion engine that includes a variable valve operating mechanism which can vary an operational characteristic of at least one of an intake valve and an exhaust valve, the oil passage construction, comprising: a first member, which is a die-cast formed product, and which has a first oil passage, of which a predetermined range upon its inner surface is a molded surface; and a second member, having a second oil passage which is communicated with the first oil passage, which is linked to the first member, wherein a surface of the first member, which is linked to the second member, is formed by a cutting process, and at least a range of the inner surface of the first oil passage being of a predetermined length from its opening end towards the inside thereof is a molded surface wherein the opening end is provided at the surface formed by the cutting process, wherein the first member is a cam housing for supporting a cam shaft which is provided upon a cylinder head of the internal combustion engine, and the second member is an auxiliary unit which is attached to the cam housing, and wherein the variable valve operating mechanism includes: a rocker shaft located on a cylinder head which is fixedly supported parallel to the cam shaft; and a control shaft which is inserted into a central axial hole of the rocker shaft so as to be displaceable in an axial direction therein, wherein the first oil passage is provided between the cylinder head and the control shaft.