Device for locking and unlocking a cover or lid on a frame by means of a key

1. Device for locking and unlocking a cover or lid on a frame by means of a key, comprising:

a lock whose element forming the locking bolt receiver is integral with the frame, and the element forming the locking bolt is integral with the cover which has an opening for access of the key to the element forming the locking bolt, which key comprises an arm having a spur-shaped operating device disposed at one end of the arm allowing the element forming the locking bolt to be operated, when the key is inserted in the opening of the cover, from a locked position in which the element forming the locking bolt is held confined in the locking bolt receiver to an unlocked position for which the element forming the locking bolt is released from the locking bolt receiver and the key is held confined in the opening of the cover;

wherein the element forming the locking bolt comprises an elastically deformable rod protruding beneath the cover appreciably perpendicular to said cover and terminating in a hook-shaped free end suitable for engaging under a rib or rigid tab of the receiver of the frame to lock the cover to the frame;

wherein the spur-shaped operating device permits elastic movement of the rod to disengage the hook-shaped end from the rib or rigid tab when the key is inserted in the opening of the cover and turned from a specific angle around the longitudinal axis of the arm of the key so as to unlock the cover; and

wherein the spur-shaped operating device of the key has an internal concavity at a free end in which the rod of the locking bolt is held in position separated from the rib or tab when the key is in a position of unlocking the cover.

2. Device according to claim 1 , further comprising a means of positioning the key relative to the rib or tab of the locking bolt receiver when inserted into the opening of the cover to allow the spur-shaped operating device of the key to be positioned in a space between the cover and the rib or tab, and in which the spur-shaped operating device can pivot freely until coming in contact with the rod of the locking bolt in order to elastically move the spur-shaped operating device away from the rib or tab and be immobilized in rotation by the elastic return force exerted by the rod of the locking bolt to a position beneath the cover in which the spur-shaped operating device axially retains the key relative to the cover so as to confine the key in the cover.

3. Device according to claim 2 , wherein the arm of the key includes a second spur at an end opposite the spur-shaped operating device of the rod of the locking bolt and cooperating with the spur-shaped operating device in order to occupy a position holding the key in the cover transverse to the opening thereof when the key is in the unlocking position.

4. Device according to claim 2 , wherein the means of positioning the key relative to the rib or tab of the receiver comprises a hole made in the rib or tab directly below the opening of the cover and suitable for receiving a cylindrical free end of the arm of the key so that at least the operating spur extending transversely to the arm above its cylindrical end can be supported on the rib or tab.

5. Device according to claim 1 , wherein the element forming the locking bolt also comprises an appreciably U-shaped part housed in the cover parallel to the outer face thereof and at the end of one of the arms the rod of the locking bolt extending perpendicularly to the plane of the U-shaped part, the two arms of which are symmetrical to a longitudinal median plane of the opening of the cover, these two arms being separated from each other by a distance greater than that of the opening of the cover.

6. Device according to claim 5 , wherein at least one of the arms of the U-shaped part of the element forming the locking bolt comprises a means, appreciably in the middle of said part, of holding the part in a housing of the cover.

7. Device according to claim 6 , wherein the holding means is composed of an arc-shaped deformation in the arm of the U-shaped part defining an outer concavity opposite to the other arm and in which a conjugate lobe of the wall of the housing in the cover snaps in place, which lobe is situated opposite the deformed arm of the U-shaped part.

8. Device according to claim 3 , wherein the spur-shaped operating device of the arm of the key has a length that is greater than that of the second spur of this arm.

9. Device according to claim 1 , wherein the opening of the cover has a transverse cross section which creates a foolproof shape.

10. Device according to claim 1 , wherein the rib or tab of the locking bolt receiver is integral with one of the side walls of the frame and extends parallel to an upper edge of the frame that supports the cover.

11. Device according to claim 1 , wherein the key is turned about one quarter turn to unlock the cover.