Continuous variable valve duration apparatus and engine provided with the same

An engine comprising:

• a continuous variable valve duration apparatus, the apparatus comprising:
• a cam unit;
• a cam formed on the cam unit;
• a camshaft inserted into the cam;
• a guide bracket;
• a guide shaft mounted on the guide bracket and disposed perpendicular to the camshaft, wherein a guide screw thread is formed on the guide shaft;
• a wheel housing disposed within the guide bracket;
• an inner wheel rotatably inserted into the wheel housing and movable perpendicular to the camshaft, the inner wheel configured to transmit rotation of the camshaft to the cam unit;
• a worm wheel disposed within the wheel housing, wherein an inner screw thread configured to engage with the guide screw thread is formed inside the worm wheel and an outer screw thread is formed on the worm wheel;
• a control shaft;
• a control worm formed on the control shaft and configured to engage with the outer screw thread;
• and
• a wheel elastic portion mounted to the wheel housing and configured to push the worm wheel toward the guide shaft and the control shaft.

A continuous variable valve duration apparatus comprising:

• a cam on a cam unit;
• a camshaft inserted into the cam;
• a guide bracket;
• a guide shaft mounted on the guide bracket and having a guide screw thread on an outer surface of the guide shaft;
• a wheel housing disposed within the guide bracket;
• a sliding shaft fixed to the guide bracket, the sliding shaft configured to guide movement of the wheel housing;
• an inner wheel rotatably inserted into the wheel housing and movable perpendicular to the camshaft, the inner wheel configured to transmit rotation of the camshaft to the cam unit;
• a worm wheel disposed within the wheel housing, wherein an inner screw thread configured to engage with the guide screw thread is formed inside the worm wheel and an outer screw thread is formed on the worm wheel;
• a control shaft;
• a control worm formed on the control shaft and configured to engage with the outer screw thread;
• and
• a wheel elastic portion mounted to the wheel housing and configured to push the worm wheel toward the guide shaft and the control shaft, the wheel elastic portion including a flat spring and a flat spring guide, the flat spring guide including guide coupling portions and a guide connecting portion formed between the guide coupling portions, wherein a gap is formed between the flat spring guide and the flat spring.