Variable valve timing mechanism with intermediate locking mechanism and fabrication method thereof

A variable valve timing mechanism with an intermediate lock mechanism, the variable valve timing mechanism varying a rotational phase of a camshaft relative to a crankshaft between a most advanced phase and a most retarded phase, and comprising a first rotary body, a second rotary body, and an intermediate lock mechanism, the first rotary body rotating synchronously with one of the crankshaft and the camshaft, the second rotary body rotating synchronously with the other one of the crankshaft and the camshaft, having a coaxial axis with the first rotary body, and accommodating the first rotary body in a relatively rotatable manner, the second rotary body being formed by fastening a first member and a second member to each other, and the intermediate lock mechanism locking rotation of the first rotary body relative to the second rotary body at an intermediate lock phase between the most advanced phase and the most retarded phase, wherein the intermediate lock mechanism includes:

• a first lock pin and a second lock pin that are arranged in the first rotary body, the first and second lock pins being projectable and retractable independently from each other;
• an advancement restricting groove arranged in the first member, the advancement restricting groove being formed in such a manner as to, when the first lock pin is projected, become engaged with the first lock pin to lock, at the intermediate lock phase, rotation of the first rotary body to an advancing side and permit, at the intermediate lock phase, rotation of the first rotary body to a retarding side;
• and
• a retardation restricting groove arranged in the second member, the retardation restricting groove being formed in such a manner as to, when the second lock pin is projected, become engaged with the second lock pin to lock, at the intermediate lock phase, rotation of the first rotary body to the retarding side and permit, at the intermediate lock phase, rotation of the first rotary body to the advancing side,
• wherein when the advancement restricting groove engages with the first lock pin to lock, at the intermediate lock phase, rotation of the first rotary body to the advancing side, the retardation restricting groove engages with the second lock pin to lock, at the intermediate lock phase, rotation of the first rotary body to the retarding side.