Door latching mechanism

A single swing door is at least temporarily converted to a double swing door by providing means for withdrawing the latch bolt sufficiently out of the latching recess in the door frame so it is beyond striking either edge of the strike plate in the door frame so that the door can be swung open in either direction.

BACKGROUND OF THE INVENTION 
While in general it is desirable, and sometimes even required, that in most 
buildings the room doors swing only one way, usually inward, there are 
many instances when it is desirable and even mandatory to be able to 
convert a single swing door at least temporarily into a double swing door. 
A typical example is in the case of toilet doors in a hospital or in a 
public building in which generally, for ambulatory cases, the doors need 
only swing one way, preferrably inward, yet should be made to accommodate 
nonambulatory cases, such as wheelchair patients, by having the doors 
possible to swing outward. This is to make it easier for a wheelchair 
patient to gain access to the room and manipulate the wheelchair. There 
are doors which have mechanical stops along the door frame which, when 
desired to convert to a double swing door, are pushed back with one hand 
and the door swung outward. These are generally awkward to operate 
especially by wheelchair patients and, in the case of the elderly, might 
be difficult to operate. Other devices for converting to double swing 
action are usually lacking in their ability to maintain the privacy that 
the party still wants to have after he enters the room. In other words, 
some of the mechanisms for double swing operation are such that the door 
can be swung open outwardly even though someone is inside the room. 
SUMMARY OF THE INVENTION 
The instant invention provides for at least temporarily operating a single 
swing door in a double swing fashion utilizing mechanisms and operating 
knobs or turnpieces in their usual fashion so as not to require any extra 
fanciful or any complex operating instructions. The strike plate in the 
door frame has one edge offset from the other so that in the normal 
operating fashion the latch bolt is withdrawn out of the opening in the 
strike plate just far enough to pass beyond the offset edge, usually 
towards the inside of the room, so that the door can be swung in that 
direction only. The latch bolt is prevented from being withdrawn or 
retracted past the other edge of the strike plate so any attempt to swing 
the door in the opposite direction is frustrated. When needed, however, 
mechanism is provided to at least temporarily remove the limitation on the 
retraction of the latch bolt so that it can be withdrawn beyond the other 
edge of the strike plate opening to permit the door to be swung out in the 
other direction. As a special feature of the invention, more than a single 
turn piece can be provided to make the double swing action possible. This 
serves as a safety feature in the event it is necessary to gain access to 
the room when there is a problem to open the door by swinging it inward. 
As another feature, in general, the invention provides for the conversion 
to double swing action to be on a one shot basis so that after the latch 
mechanism is operated to swing the door in the other than usual direction, 
it automatically returns to a single swing action and the user must again 
selectively convert it back to double swing action, if desired. 
DESCRIPTION OF THE INVENTION 
FIG. 1 is a simplified cutaway plan view illustrating the general operation 
and function of the invention; 
FIG. 2 is a cutaway view showing the various mechanisms used in the 
preferred embodiment of the invention; and 
FIG. 3 is a simplified somewhat detailed illustration of a push button 
mechanism.

A door frame 10 contains a recess 11 covered over in part by a strike plate 
12 having an opening 13 to receive a latch bolt 14 carried by door 15. One 
edge 12A of the strike plate opening is offset inward into the door frame 
from the other edge 12B. In normal operation, the latch bolt 14 is being 
urged by spring action into recess 11 through strike plate opening 13. To 
open the door the latch bolt is withdrawn by a turn piece, such as a knob, 
not shown, out of the recess 11 beyond edge 12A but not beyond edge 12B. 
The door can then be swung inward past edge 12A and the latch bolt 14 
rides over hump 12C on the strike plate. The door cannot be swung outward 
because the latch bolt 14 strikes the other edge 12B of the strike plate 
opening. 
Turning next to FIG. 2, the latch bolt 14 is urged by spring 16 around the 
latch bolt rod 17 towards the latching recess 11 through the strike plate 
opening 13. In conventional fashion, a turn piece such as a door knob, not 
shown, having a suitably structured rod inserted in the opening 18A of 
knob hub 18 when turned causes retractor lever arm 19 to swing about its 
pivot point 20 by shoulder 18B of knob hub 18 pushing against the 
extension 19A. Near its upper edge retractor lever arm 19 rests against 
the latch bolt rod shoe 21 which is attached rigidly to the rear of latch 
bolt rod 17. The retractor lever arm 19 swinging counterclockwise about 
its pivot point 20 retracts or withdraws the latch bolt 14 against the 
action of the spring 16. The limit of travel of the retractor lever arm 19 
and correspondingly the latch bolt 14 is reached when the top end 19B 
strikes against stop 22. The design is such that this will be far enough 
to allow the latch bolt 14 to go beyond the offset edge 12A of the strike 
plate opening but not beyond edge 12B. This then permits the door to be 
swung conventionally in a single direction. 
Another turn piece, not shown, with a suitably designed shaft to mate with 
the opening 25A of turn piece hub 25 is normally located on the outside or 
corridor side of the door. When it is turned, it causes its associated 
turn piece retractor lever arm 26 to pivot about the hub 25 so that its 
lower end 26A pushes against the latch bolt rod shoe 21 to retract the 
latch bolt 14. In this instance, however, the retractor lever arm 26 is 
designed so that the end arm 26A avoids engaging or striking the stop 
member 22 so that the latch bolt 14 can be withdrawn beyond the edge 12B 
of the strike plate and the door can be swung outward into the corridor. 
It is contemplated by this invention that a turn piece can be located to be 
operated from either the inside or outside, or both, at hub 25 and 
similarly a turn piece such as a knob or the like can be located inside or 
outside, or both, to operate knob hub 18. Ordinarily, a turn piece may be 
mounted on the inside of the door concentric with an outside turn piece at 
hub 25 for the purpose of locking the door from the inside for privacy. It 
is contemplated that the same turn piece can be used by being spring 
loaded so that it can be pushed to engage the opening 25A and then to be 
operated in the same fashion as described above to withdraw the latch bolt 
far enough past strike plate edge 12B to enable the door to be swung 
outward. 
To allow the turn piece at knob hub 18 to be used to swing the door 
outward, a push button 30 (FIG. 3) which is normally urged outward by 
spring 31 is inserted so that its plunger 32 slides into slot 33. The 
tapered end 32A of the plunger 32 pushes against the top of the forward 
end of restrictor lever arm 34 to move it downward about its pivot point 
34A. The stop member 22 is mounted on the far end of restrictor lever arm 
34 so that as the latter pivots about its pivot point 34A the former is 
lifted upward far enough so that it is avoided by the upper section 19B of 
retractor lever arm 19 when it is moved by turning the turn piece mounted 
in the opening 18A. In this fashion then, the turn piece can be turned far 
enough to withdraw latch bolt 14 out of the latching recess 11 beyond edge 
12B of the strike plate so that the door can be swung outward into the 
corridor. 
When the latch bolt 14 is withdrawn in this fashion, the latch bolt kickoff 
40 attached to the rear of the latch bolt 14 strikes the restrictor lever 
arm 34 at 34C causing the restrictor lever arm 34 to pivot in the opposite 
direction about pivot point 34A so that stop member 22 is swung back 
toward its stop location so that when the latch bolt is released and 
allowed again to insert into the recess 11 the latching mechanism will now 
be reset to limit the door to single swing action. The push button will 
again have to be depressed in order to return it temporarily to a double 
swing operation by use of the turn plate at hub 18. 
In order to permit the push button 30 to be momentarily depressed and then 
released and still permit double swing action with the turn piece at hub 
18 so that the operator can use the same hand to depress the button and 
then move the turn piece, a mechanism is provided to temporarily latch 
restrictor lever arm 34 into the position where stop 22 is not in play. A 
link 41 pivots about pivot point 41A by the action of pin 35 riding in the 
slot 34B so that the lower part of link 41 swings counterclockwise. A pin 
41B carried by link 41 rides against spring 42 which is shaped to hold or 
latch link 41 in one of two positions. When the push button 30 is 
depressed, the link 41 acting against the spring 42 will be held in the 
position whereby the stop 22 is out of the way. When the latch bolt 
kickoff 40 strikes the restrictor arm 34, the link 41 acting against 
spring 42 is caused to return to the other condition where stop 20 is back 
in its stop location. 
It should be recognized that the invention contemplates that the push 
button and associated mechanisms can be located on the inside or the 
outside of the door or both. It is also contemplated that suitable 
linkages can be provided to cause the mechanism to operate in the fashion 
described whether the turn pieces are turned clockwise or 
counterclockwise. 
The elongated bar 43 shown in FIG. 2 is used to lock the latching mechanism 
to provide privacy. It is not part of the invention but is shown merely to 
illustrate that the double swing action, as described above, can be 
achieved and privacy can still be provided.