Lock having simplified structure

1. A lock, comprising:

a lock core structure, comprising:

a restriction unit having a passage penetrating therethrough to form a first opening and a second opening on two opposite sides of the restriction unit, wherein an extension wall is formed in the passage to face the second opening;

a lock core disposed in the passage, the lock core being movable relative to the restriction unit in an axial direction and comprising:

an end face facing the extension wall; and

an extension portion disposed on one side of the lock core close to the first opening, the extension portion extending under the extension wall toward the first opening and selectively protruding outside the first opening; and

an elastic unit disposed between the end face and the extension wall, two ends of the elastic unit respectively contacting the end face and the extension wall; and

a movable unit selectively contacting the lock core and capable of performing a reciprocal rotation, rotation of the movable unit is linked to axial movement of the lock core;

wherein the elastic unit releases an elastic force to push the end face so as to drive the lock core to move relative to the restriction unit and away from the movable unit.

2. The lock of claim 1 , wherein the movable unit selectively couples with the lock core in the axial direction and has a rotation axis perpendicular to the axial direction.

3. The lock of claim 1 , wherein the restriction unit has a notch formed under the extension wall; the notch communicates with the first opening and the second opening; the extension portion of the lock core passes through the notch and reciprocally moves in the notch; the restriction unit further has a stop zone formed in the passage and on one side of the notch away from the first opening; the extension portion moves away from the movable unit and stops at the stop zone.

4. The lock of claim 3 , wherein the restriction unit comprises a first seat unit and a second seat unit connected in series; the notch is formed in the first seat unit; the stop zone is a surface of the second seat unit connected to the first seat unit.

5. The lock of claim 1 , wherein the restriction unit further has a through hole substantially crossing the axial direction and communicating with the passage; the lock core further has a groove selectively corresponding to the through hole.

6. The lock of claim 5 , wherein the lock core structure further comprises a movable pin movably disposed in the through hole; a portion of the movable pin moves into the groove corresponding to the through hole to limit movement of the lock core.

7. The lock of claim 1 , wherein the lock core has a closed outer surface.

8. The lock of claim 1 , further comprising a fixing unit disposed on one side of the lock core structure that is connected to the movable unit.

9. The lock of claim 8 , wherein the fixing unit has an indentation; the movable unit has a latch end; the movable unit reciprocally rotates to drive the latch end to move relative to the indentation; the latch end moves toward the indentation and is received in the indentation.

10. The lock of claim 8 , further comprising a shell part fitted on the lock core structure and a portion of the movable unit, wherein the fixing unit is a portion of the shell part.