Field of Search:
292/207,226,228,244,DIG.26
Claims:
I claim
1. A door latch comprising:
2. The door latch of claim 1 wherein said handle is formed with two of said axial slots spaced 180° from each other and said latch bolt is formed with two of said camming surfaces spaced 180° from each other, one said camming surface being aligned with each said axial slot.
3. The door latch of claim 1 including a manual locking button secured to said locking slide and extending through an elongate aperture in said casing for manual movement of said locking slide.
Description:
FIELD OF THE INVENTION
The present invention relates to a door latch having a latch bolt pivotally mounted on a rotatable handle.
BACKGROUND OF THE INVENTION
The prior art, as exemplified by U.S. Pats. Nos. 2,707,121; 2,801,869; 2,851,871; 2,950,137; and 3,100,388, has recognized the primary advantage of a door latch in which the interior handle is rotatable and has the latch bolt pivotally mounted thereon. In such a latch it is not necessary to rotate the handle when closing the door since the latch bolt is pivoted by the strike until it passes thereby whereupon it is resiliently urged into engagement with the strike. However, in many of such latches the latch bolt may be pivoted back into engagement with the strike while the locking mechanism restraining the handle against rotation remains engaged. It is thereby possible for one to inadvertently engage the locking mechanism when the door is open and, when the door closes, to find himself locked outside. To guard against this possibility the structures disclosed in U.S. Pat. Nos. 2,801,869; 2,950,137; and 3,100,388 have utilized mechanisms for automatically disengaging the locking mechanism when the latch bolt is pivoted by the strike. However, such mechanisms have generally been complex and they have not permitted the use of a single door latch construction for both right and left hand opening doors.
SUMMARY OF THE INVENTION
According to the present invention there is provided a door latch comprising a casing for mounting on the interior of a door and having a handle rotatably supported thereby, the handle being formed with an axial slot extending from its periphery inward toward its axis of rotation. A locking slide is supported on the interior face of the casing for sliding movement perpendicular to the axis of rotation of the handle, the locking slide being formed with a locking and camming tongue extending parallel to the axis of the handle and through a slot formed in the casing adjacent the handle for insertion into the axial slot in the handle to lock the handle against rotation. A latch bolt is mounted on the handle for rotation with the handle and for pivotal movement relative thereto, the latch bolt being resiliently urged to a strike engaging position and being formed with a camming surface adjacent the handle to cam the locking and camming tongue out of the slot in the handle upon pivotal movement of the latch bolt against the resilient urging force. The door latch of the present invention is extremely simple in construction and a single mechanism may be used on either a right or a left hand opening door.
THE DRAWING
In the drawing:
FIG. 1 is an elevation view of a door latch constructed in accordance with the present invention and mounted on a door;
FIG. 2 is an edge elevation view of the latch of FIG. 1 illustrating its assembly with an outside door knob;
FIG. 3 is a top view of the latch;
FIG. 4 is a rear elevation view of the latch; and
FIG. 5 is a partial view similar to that of FIG. 1 showing the latch in the locked position.
The door latch of the present invention, generally designated 10, comprises a casing 12 for mounting on the interior of a door 13, a handle 15 rotatably supported by the casing 12, a locking slide 17 supported on the interior face of the casing 12 and a latch bolt 19 mounted on the handle 15 for rotation with the handle and for pivotal movement relative thereto.
The inner casing 12 is molded of metal and it has a rectangular shape with a rim 21 projecting from its interior face around its periphery. A pair of similar hollow cylindrical projections 22 and 23 also project from its interior face and a short, hollow cylindrical projection 24 projects from its exterior face between the interior projections 22 and 23. As illustrated in FIG. 2, the interior projections 22 and 23 serve to locate mounting holes drilled through the door 13 and align with threaded cylindrical projections 28 extending from an exterior casing 27 having the same general configuration as the interior casing 12. The interior casing 12 and the exterior casing 27 are secured together by a pair of screws 29 inserted through the projections 22 and 23 and threaded into the projections 28 of the exterior casing 27.
The door handle 15 extends from the outer face of the interior casing 12 perpendicular thereto for a short distance and it then turns through a 90° angle to facilitate grasping and rotating of the handle about an axis perpendicular to the face of the casing 12. The handle 15 extends through the exterior projection 24 in the caisng 12 and on the inner face of the casing 12 it is flared to permit free rotation of the handle 15 relative to the casing 12 without permitting axial movement thereof. At its connection to the interior casing 12 the handle 15 is formed with a square axially extending cavity 33 for receiving a square spindle 34. The spindle 34 extends through the door 13 and is similarly coupled to a door knob 30 supported for rotation by the exterior casing 27. A pair of opposed compression springs (not shown) coupled between the door knob 30 and the exterior casing 27 always urge the knob 30 and the handle 15 coupled therewith to a predetermined position, as is conventional.
Adjacent the exterior projection 24 of the casing 12 the handle 15 is formed with a locking disk 36 which is coaxial with the axis of rotation of the handle. The locking disk 36 is formed with a pair of axial slots 37 and 38 extending from its periphery inward toward its axis of rotation and spaced 180° from each other.
The locking slide 17 is supported for sliding movement perpendicular to the axis of rotation of the handle 15. The major portion thereof lies against the inner face of the casing 12 and it is formed with an elongate aperture 39 fitting over the cylindrical projection 23 to guide the movement of the locking slide. The locking slide is formed with a locking and camming tongue 40 extending parallel to the axis of the handle 15 and through a rectangular slot 41 formed in the interior casing 12. The slot 41 extends into the projection 24 at the outer face of the casing 12 to permit insertion of the locking and camming tongue into an axial slot 37 or 38 of the handle locking disk 36 upon alignment thereof with the slot 41.
A manual locking button 43 is formed with a shaft that extends through an elongate aperture 45 in the interior casing 12 and is riveted to the locking slide 17 for manual sliding movement thereof. The locking button 43 is resiliently biased outward by compression spring 46 thereby maintaining the locking slide 17 against the inner face of the interior casing 12.
The latch bolt 19 is mounted on the handle by a pivot pin 51 for rotation with the handle and for pivotal movement relative thereto. The latch bolt 19 is resiliently urged to a strike engaging position by a compression spring 52 captured between the handle 15 and the inner surface of the latch bolt 19. A pair of stops 54 projecting from the locking disk 36 of the handle 15 normally engage stepped portions at the trailing edge of the latch bolt 19 to prevent the compression spring 52 from urging the latch bolt away from the handle beyond its strike engaging position.
Adjacent the locking slots 37 and 38 in the handle locking disk 36 the latch bolt 19 is turned inward against the handle to define camming surfaces 56 and 57, one aligned with each of the locking slots 37 and 38, respectively. The camming surfaces 56 and 57 extend axially from adjacent the locking disk 36 to be aligned in a direction perpendicular to the handle axis with the locking and camming tongue 40 when it is inserted in the associated handle locking slot 37 or 38, respectively.
In use, the door latch 10 is assembled on a door 13 with the door knob 30 as aforedescribed. In the illustrated embodiment the door hinges are to the right as viewed in FIG. 1 and the latch bolt 19 is urged outward to engage a strike 59 on a door frame. With the locking slide 17 in the positioned illustrated in FIGS. 1 through 4 the door is unlocked and the handle 15 and the knob 30 freely rotate together upon turning to disengage the latch bolt 19 from the strike 59 to permit opening of the door. Upon closing of the door the nose of the latch bolt 19 contacts the strike 59 which urges it inward against the compression spring 52 until it passes the strike 59 whereupon it is urged outward to its strike engaging position.
To lock the door it is only necessary that the locking button 43 be moved upward in FIGS. 1 and 2 to move the locking and camming tongue 40 thereof into the aligned slot 38 in the handle locking disk 36. This locks the handle 15 and the knob 30 against rotation as illustrated in FIG. 5. However, if the door 13 is open at the time the lock is engaged the door cannot close with the latch 10 remaining in the locked position. For, when the nose of the latch bolt 19 contacts the strike 59 and is moved against the force of compression spring 52 its camming surface 57 engages the locking and camming tongue 40 and urges it downward as viewed in FIG. 5 out of the slot 38 in the locking disk 36.
It can also readily be seen that if the door 13 were to hinge in the opposite direction such that the strike 59 would be to the right of the interior casing 12 as viewed in FIG. 1, it is only necessary that in assembly and prior to coupling the handle 15 to the knob 30 by the spindle 34, the handle be rotated 180° from the position illustrated in FIG. 1. In this case the locking slot 37 in the disk 36 will normally align with the locking and camming tongue 40 and the camming surface 56 will act to cam the locking and camming tongue 40 out of the locked position if the door 13 attempts to close with the latch 10 in the locked position.