Continuous variable valve duration apparatus and engine provided with the same

An engine comprising:

• a camshaft;
• a slider mounted to the camshaft and having a camshaft sliding key;
• a cam portion having a cam and a cam sliding key, into which the camshaft is inserted, and having a variable relative phase between the cam and the camshaft;
• a roller ring connected with the camshaft sliding key and the cam sliding key;
• a roller ring guider to which the roller ring is rotatably inserted, the roller ring guider slidably inserted into a cylinder head, and roller ring having a first sliding pin hole and a second sliding pin hole;
• a first pin of which a sliding key slot for the camshaft sliding key to be slidably inserted is formed thereto, and the first pin rotatably inserted into the first sliding pin hole;
• a second pin of which a sliding key slot for the cam sliding key to be slidably inserted is formed in the opposite direction of the sliding key slot of the first pin, and the second pin rotatably inserted into the second sliding pin hole;
• and
• a control portion selectively changing a position of the roller ring guider to control a rotation center position of the roller ring.