Mortise lock resistant to blunt force attacks

1 . A lockset comprising:

a lockset body;

a bolt constrained to move between retracted and projected positions along a bolt axis;

a slot through a bottom side of the bolt, the slot having a closed end proximal to a front face of the bolt, the front face of the bolt extending over the closed end of the slot, and the slot extending backwardly from the front face of the bolt in a direction parallel to the bolt axis;

at least one lever housed within the bolt slot; and

a locking catch formed in or mounted to the lever;

a retract slide that carries the bolt between the retracted and projected positions;

a thumbturn that, when operated, forces the retract slide to move into the projected position to lock a door in which the lockset is installed, or to move into the retracted position to unlock the door;

a tail of the thumbturn coupling the thumbturn to the retract slide; and

a channel formed in the retract slide into which an end of the thumbturn tail resides throughout all positions between retracted and projected of the bolt;

wherein when the bolt is projected, the locking catch is forced to extend out of the slot at a top, bottom, or side of the bolt;

wherein when the bolt retracts from the projected position, the locking catch withdraws into the slot so that it can clear a strike plate aperture and a scalp plate aperture;

wherein when the bolt is fully projected, the thumbturn tail is placed in opposition to a forward side of the channel;

wherein when an attempt is made to card the lockset, the thumbturn tail resists the attempt by counteracting pressure from a forward side of the channel to the thumbturn tail.

2 . The lockset of claim 1 , wherein:

the locking catch is an ear, a tab and/or a hook; and

the lever is pivotally mounted to the bolt.

3 . The lockset of claim 1 , wherein:

the lockset is a mortise lockset; and

wherein when the bolt is projected into a door frame or another door that provides a complementary recess for the locking catch, the locking catch extends into the complementary recess and, when a blunt impact force is exerted against the lockset to force the bolt to retract, the locking catch presses against a strike plate of the door frame or other door, thereby preventing retraction of the bolt.

4 . The lockset of claim 1 , wherein the lockset further comprises:

stationary posts that are mounted within the mortise body and that are stationary with respect to the mortise body;

wherein the lever has an edge, and the edge has a curvingly contoured section that cams against the stationary posts to lift and lower the lever between a withdrawn position where the locking catch is withdrawn into the bolt slot and a lockingly engaged position in which the locking catch extends out of the bolt slot.

5 . The lockset of claim 1 , wherein one or more cams are used to control the movement of the locking catch relative to the bolt and no spring is used to bias the lever or the locking catch.

6 . The lockset of claim 1 , wherein the channel has left and right sides whose upper portions diverge from a low midpoint on the retract slide to a top of the retract slide, and whose lower portions diverge from the low midpoint on the retract slide to a bottom of the retract slide;

wherein when the bolt is projected, the thumbturn tail is adjacent to the lower portion of a frontmost side, which is either the left side or the right side, closest to the bolt;

wherein a blunt force against the lockset to force the bolt to retract is impeded by the thumbturn tail against the lower portion of the frontmost side.

7 . A lockset for a sliding door or a double door, the lockset comprising:

a lock body with a cam post and a scalp plate;

a bolt movable between retracted and projected positions with respect to the lock body;

a catch incorporated into or carried by a lever that is at least partially housed within the bolt and that, when the bolt approaches the projected position, automatically extends out of the bolt to lockingly engage a door frame or an opposite door of a sliding double door; and

a contour along the lever, the contour comprising a glide edge segment and a first convex section forward of a concave section which itself is forward of a second convex section, wherein:

as the bolt is just beginning to retract from the projected position, the first convex section cams against the cam post, forcing a withdrawal of the catch from its lockingly engaged position;

as the bolt retracts further, the glide edge segment comes into contact with an upwardly facing edge of a scalp plate aperture, which supports the catch from drooping due to gravity; and

as the bolt retracts even further, the glide edge segment retreats behind the scalp plate aperture and comes into contact with the cam post, so that the cam post replaces the upwardly facing edge of the scalp plate aperture as a support for the catch to prevent it from drooping low enough to potentially cause the lever to jam against the scalp plate when an attempt is made to project the bolt;

as the bolt projects into a bolt receptacle of a door frame or opposite door, the concave section and/or the second convex section cams against the cam post, forcing the catch into locking engagement with the door frame or opposite door.

8 . The lockset of claim 7 , further comprising:

a recessed linear section of the lever that rests upon and is long enough to bridge both the scalp plate and a strike plate when the bolt is in the projected position and is deep enough to enable the catch to lockingly engage a doorframe or an opposite door of a double door.

9 . A mortise lockset for a sliding door or a double door, the mortise lockset comprising:

a mortise body;

a thumbturn;

a cam post;

a bolt with a slot; and

a lever incorporating or carrying a catch configured for movement between an inactive position withdrawn into the bolt slot and an active position extending out of the bolt slot and into a complementary aperture of a door frame or of a second door;

a retract slide that carries the bolt between the retracted and projected positions and that is operatively connected to the thumbturn;

a tail of the thumbturn coupling the thumbturn to the retract slide; and

a channel formed in the retract slide into which an end of the thumbturn tail resides throughout all positions between retracted and projected of the bolt, wherein:

the thumbturn, when operated, forces the retract slide to move into the projected position to lock a door in which the lockset is installed, or to move into the retracted position to unlock the door;

when the bolt is fully projected, the thumbturn tail end is placed in opposition to a forward side of the channel; and

when a blunt force attack is made against the lockset to force the fully projected bolt to retract, the attack is impeded by the thumbturn tail end against a wall of the channel.

10 . The mortise lockset of claim 9 , wherein the lever is not spring biased into a catch-withdrawing or catch-extending position with respect to the bolt.

11 . The mortise lockset of claim 9 , wherein an edge of the lever comprises a first convex camming contact region that is configured to cam against the cam post as the bolt, when fully projected, begins to be retracted, creating a camming action that lifts the catch up into a withdrawn position within the bolt, clearing a strike plate of a door frame or second door that provides a bolt and catch receptacle for receiving the bolt and the catch.

12 . The mortise lockset of claim 11 , wherein the lever edge comprises a second convex camming contact region and a concave span between the first and second convex camming contact regions;

wherein when the bolt is being projected and after it has cleared the strike plate, the concave span and/or the second convex camming contact region cams against the cam post, forcing the catch to extend out of the bolt slot and into the bolt and catch receptacle.

13 . The mortise lockset of claim 11 , wherein the lever edge comprises a recess forward of the first convex camming contact region that extends far enough to span a scalp plate of the mortise lockset and the strike plate of a door frame or second door when the door or doors are closed.

14 . The mortise lockset of claim 13 , wherein the lever edge comprises a glide edge segment that is configured to ride across a lower edge of the scalp plate of the mortise lockset at least part of the bolt's travel between retracted and projected positions.

15 . The mortise lockset of claim 14 , wherein:

the glide edge segment includes a rearmost glide edge point; and

movement of the bolt between retracted and extended positions defines a travel profile for the rearmost glide section point.

16 . The mortise lockset of claim 15 , wherein the travel profile, generated from a transition from a retracted bolt to a projected bolt, comprises a substantially linear first section, a substantially linear second section elevated above the first section, and a third section that descends from the second section.

17 . The mortise lockset of claim 16 , wherein the first section of the travel profile delineates the position of the rearmost glide edge point as the bolt travels from a position at or proximate its most retracted position to a position in which a leading glide edge point is proximate to the strike plate of a door frame or corresponding double door.

18 . The mortise lockset of claim 16 , wherein the second section of the travel profile corresponds to the position of the rearmost glide edge point as the bolt traverses the strike plate of the door frame or corresponding double door.

19 . The mortise lockset of claim 16 , wherein the travel profile includes a curved fourth section intermediate the first and second sections reflecting the camming action of the lever's edge against the cam post to raise the catch farther up into the bolt slot to ensure that the bolt clears the strike plate as the bolt continues to travel toward a completely extended position.

20 . The mortise lockset of claim 16 , wherein the third section of the travel profile is an elliptical section whose downward steepness illustrates the sharp downward turn that the catch makes very shortly after the rearmost glide edge point clears the strike plate.