U.S. patent number 3,811,717 [Application Number 05/336,932] was granted by the patent office on 1974-05-21 for latch bolt stop lever for fire door lock sets.
This patent grant is currently assigned to Sargent and Company, Division of Walter Kidde & Co. Inc.. Invention is credited to Lars E. Erickson, Alfred E. Floyd.
United States Patent |
3,811,717 |
Floyd , et al. |
May 21, 1974 |
LATCH BOLT STOP LEVER FOR FIRE DOOR LOCK SETS
Abstract
This specification discloses a fire door lock set incorporating
a latch bolt having a latch bolt stop lever which is normally
maintained in an ineffective position by a fusible pin, but which
drops into a position holding the head of the latch bolt in door
closing position when the pin melts at a predetermined temperature
caused by a fire condition. The present invention relates to the
lock set incorporating a latch bolt and associated mechanism in a
fire door and is concerned primarily with a latch bolt stop lever
which is under the control of a fusible pin.
Inventors: |
Floyd; Alfred E. (North
Guilford, CT), Erickson; Lars E. (Clinton, CT) |
Assignee: |
Sargent and Company, Division of
Walter Kidde & Co. Inc. (New Haven, CT)
|
Family
ID: |
23318343 |
Appl.
No.: |
05/336,932 |
Filed: |
March 1, 1973 |
Current U.S.
Class: |
292/92; 49/1;
292/DIG.66; 16/48.5; 292/153 |
Current CPC
Class: |
E05B
65/104 (20130101); Y10T 292/1031 (20150401); Y10S
292/66 (20130101); Y10T 292/0908 (20150401); Y10T
16/22 (20150115) |
Current International
Class: |
E05B
65/10 (20060101); E05f 015/20 () |
Field of
Search: |
;292/92,153,DIG.66
;70/DIG.10 ;49/1,7,8 ;16/48.5 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Wolfe; Robert L.
Attorney, Agent or Firm: Schellin; Eric P. Hoffman; Martin
P.
Claims
1. In a fire door lock set including a housing presenting a wall
structure, a latch bolt having a bolt head presenting a top face
and a rear face, spring means normally biasing said bolt head into
door closing position and a handle pivotally mounted on the wall
structure and operatively connected to the latch bolt to retract
the same against the influence of said spring means, the
improvement consisting of a lock set comprising:
a. a latch bolt stop lever pivotally mounted at one end on said
wall structure and having a notch at its other end;
b. a fusible pin mounted on said wall structure and received in
said notch to normally maintain said lever in an upraised
ineffective position in which it does not interfere with movement
of said bolt head, and
c. means for limiting downward swinging movement of said lever when
said
2. The lock set of claim 1 in which the means for limiting downward
swinging movement of the latch bolt stop lever consists of a tab
formed on said lever and extending beyond said notch and which
engages the upper face of the bolt head when the lever swings
downwardly, and an end portion below said notch which engages the
rear face of the bolt head after the lever has swung downwardly and
reaches its lowermost position as
3. The lock set of claim 1 in which the means for limiting downward
swinging movement of the latch bolt stop lever consists of an
abutment
4. The lock set of claim 3 together with an optional torsion spring
associated with the pivotal mounting of the latch bolt stop lever
which
5. The lock set of claim 3 in which the latch bolt stop lever is
formed with a tab below the notch which engages the rear face of
the bolt head
6. The lock set of claim 1 in which the fusible pin is of zinc or
other suitable element or alloy of suitably low temperature melting
characteristics.
Description
BACKGROUND OF THE INVENTION
At the present time, fire doors are included in many structures and
are provided for the purpose of maintaining an exit closed during a
fire for the purpose of preventing the spread of the fire. Lock
sets incorporating latch bolts are employed to maintain the fire
doors in closed position and it is, of course, necessary to provide
a mechanism to retract the latch bolt when the door is to be
opened. One type of lock set incorporating a latch bolt for fire
doors which is now meeting with widespread usage includes springs
which bias the head of the latch bolt into the door closing
position. They also include a horizontally disposed handle which is
depressed and through mechanical connections retracts the bolt head
from closing position. It has been found that in the event of a
fire, temperatures reach the point where the springs are annealed
and thus lose their holding power. Under these conditions, the
weight of the handle will retract the bolt head because the latter
is no longer held in door closing position by the springs. The
present invention is founded on the concept of providing a lock set
incorporating a latch bolt stop lever which is maintained in
ineffective position under normal conditions by a fusible pin, but
which will drop into effective position maintaining the bolt head
in door closing position when the pin melts.
OBJECTS OF THE INVENTION
With the foregoing conditions in mind, the present invention has in
view the following objectives:
1. To provide a lock set incorporating a latch bolt mechanism for a
fire door which includes a latch bolt having a bolt head, spring
means normally biasing the bolt head into door closing position and
a pivotally mounted handle which assumes an upraised horizontal
position when the bolt head is in door closing position, with a
latch bolt stop lever that is held in ineffective position by a
fusible pin under normal conditions, but which falls into effective
position engaging the bolt head to maintain the latter in door
closing position when the pin melts.
2. To provide, in a fire door a lock set incorporating a latch bolt
mechanism of the type noted, a latch bolt stop lever which falls
into effective position solely by gravity action and which includes
an abutment for limiting its falling movement to assure of its
proper engagement with the bolt head.
3. To provide, in a fire door a lock set incorporating a latch bolt
mechanism of the character aforesaid, a latch bolt stop lever which
is moved into effective position engaging the bolt head by gravity
action and as may be supplemented by a spring together with an
abutment element for limiting such movement.
4. To provide, in a fire door a lock set incorporating a latch bolt
mechanism of the kind described, a latch bolt stop lever which is
pivotally mounted at one end on the housing which encases the lock
set and which has a notch at the other end which receives the
fusible pin which is also secured to the housing.
5. To provide, in a fire door lock set of the type noted, a
pivotally mounted latch bolt stop lever having a tab projecting
from the notched end which functions as an abutment that engages
the bolt head when the latch bolt stop lever falls into effective
position.
6. To provide, in a fire door lock set of the character aforesaid,
an abutment pin which is secured to the housing below the latch
bolt stop lever to limit its downward swinging movement.
Various other more detailed objects and advantages of the
invention, such as arise in connection with carrying out the above
ideas in a practical embodiment, will, in part, become apparent
and, in part, be hereafter stated as the description of the
invention proceeds.
SUMMARY OF THE INVENTION
The foregoing objects are achieved by two embodiments. In one
embodiment, a latch bolt stop lever is pivotally mounted at one end
to a wall of the housing which encases the latch bolt mechanism.
The other end of this lever is formed with a notch and a tab
extending therefrom on the upper side thereof. The notch receives
the fusible pin which is secured to the housing wall and when this
pin melts the lever drops until the tab engages the upper surface
of the bolt head. In this position, the end portion of the lever
below the notch engages the inner surface of the bolt head to
securely hold it in door closing position.
In a second embodiment, a latch bolt stop lever is pivotally
mounted at one end of the housing wall and its other end is formed
with a notch that receives the fusible pin. When this pin melts,
the lever will exhibit a tendency to fall under gravity action, but
this tendency may be supplemented and the required movement further
assured by a spring that is coiled about the pivotal pin on which
the lever is mounted. An abutment for limiting downward movement of
the lever is provided as an element separate from the lever and
takes the form of a pin secured to the housing wall.
For a full and more complete understanding of the invention,
reference may be had to the following description and the
accompanying drawings wherein:
FIG. 1 is a vertical section through the housing for a fire door
lock set incorporating a latch bolt mechanism with door closing
position of the latch bolt being illustrated in full lines and a
retracted position by broken lines;
FIG. 2 is a detailed view depicting the latch bolt stop lever in
effective position;
FIG. 3 is a detailed perspective illustrating the effective
position of the latch bolt stop lever in full lines and the
ineffective position in broken lines;
FIG. 4 is a side view of a modified form of the fire door lock set
and the latch bolt stop lever with the latter in ineffective
position;
FIG. 5 is a detailed view in side elevation of the latch bolt stop
lever in effective position, and
FIG. 6 is a detailed perspective of the latch bolt stop lever in
effective position.
DESCRIPTION OF THE FIRST EMBODIMENT
Referring now to the drawings, wherein like reference characters
denote corresponding elements throughout the several views, and
more particularly to FIGS. 1, 2 and 3, a fire door is represented
at 9 and the outer plate 10 and the inner plate 14 of the lock set
are formed with an opening at 11 through which a bolt head 12
extends when the fire door is closed. It will be understood that
the bolt head 12 is received in a strike in the door jamb or frame
to maintain the door closed.
Lock bolt mechanism housing is represented generally at 13. It
comprises an outer decorative plate 10 and an inner plate 14 which
is secured to the outer plate 10 in any preferred manner and from
which tabs 15 are struck. The housing proper comprises an upper
wall 16 secured to one of the tabs 15 by screws 17 and a lower wall
18 secured to the other tab 15 by a screw or pin (not illustrated
which passes through openings 19. Housing 13 also includes a rear
wall 20 remote from plate 14 and a pair of side walls, one of which
is shown at 21.
A latch bolt tail 22 has one end secured to bolt head 12 and its
other end is formed with a tail-piece 23. It passes through a guide
24 secured to the wall structure. A light expansion coil spring 25
is coiled about latch bolt tail 22 and biases the bolt head 12 into
door closing position.
A handle 26 is drivably connected to shaft 27 rotatably supported
in the wall structure 21. It projects from the surface of the fire
door and is pivotally movable by hand and is supported in a bearing
mounted on the surface of the fire door (not illustrated). The
inner end of handle 26 is attached to a hub which is formed with an
upstanding tongue 28 which engages a stop 29 secured to wall
structure 21 to limit upward swinging movement of handle 26. The
hub which engages the inner end of handle 26 is also formed with a
downwardly extending tongue 30 which is engaged by a plunger 31
which is biased by an expansion coil spring 32 mounted on wall
structure 21 to rotate the handle upwardly.
A latch bolt actuating member 33 is swingably mounted on a pivot
pin 34 mounted on wall structure 21. Member 33 has an upper end
portion 35 which engages latch bolt tail-piece 23.
Under normal conditions, springs 25 and 32 bias the bolt head 12
into door closing position. However, handle 22 may be depressed
against the influence of these springs to cause tongue 28 to engage
member 33 and retract the bolt head 12 under the influence of the
pressure exerted by end portion 35 against tail-piece 23.
The influence of spring 32 may be supplemented or replaced by a
torsion spring 36 coiled about a pin 37 secured to wall structure
21 and having one end 38 secured to an anchorage 39 on the wall
structure 21 and a second end 40 which is received in a recess in
end portion 35 of member 33.
The structure above described is more or less conventional and well
known in fire door lock set mechanisms. In accordance with the
present invention, a latch bolt stop lever 41 is pivotally mounted
at one end on a pin 42 secured to wall structure 21. Lever 41 is
formed with a notch 43 at the end remote from pivot pin 42 and
received in notch 43 is a fusible pin 44. Pin 44 is of a metal
which will melt at a predetermined required temperature. Zinc is
one example of such a metal. Midway its extremities, lever 41
carries a spring abutment 45 against which may be engaged by the
end of a torsion spring 46 which is coiled about pivot pin 42. The
other end of spring 46 may be engaged against pin 39 mounted on
wall structure 21. At an appropriate point below lever 41 is an
abutment element 47 mounted on wall structure 21. It will be noted
that lever 41 has a tab 48 which projects beyond the lower side of
notch 43.
OPERATION OF FIRST EMBODIMENT
Under normal conditions of usage of the fire door lock set above
described, the latch bolt stop lever 41 assumes the horizontal
ineffective position illustrated in FIG. 1 in which the tab 48 is
disposed above bolt head 12 and in no way interferes with the
operation either of retracting bolt head 12 into door opening
position or of having it move into door closing position under the
influence of the springs above described. Should a fire occur, any
of the springs 25, 32 or 36 may become annealed, in which event
they lose their holding power and the weight of handle 26 would
cause the bolt head 12 to be retracted. However, when the
temperature generated by the fire is sufficiently great, the
fusible pin 44 melts and the lever 41 falls downwardly under
gravity action and as may be supplemented by spring 46 until it
engages abutment element 47. In this position, tab 48 on the end of
lever 41 engages the rear face of bolt head 12 and thus prevents
its retraction.
SECOND EMBODIMENT
This embodiment which is illustrated in FIGS. 4, 5 and 6, is shown
as mounted on door 9 the outer plate 10 and the inner plate 50 of
the lock set both of which have an opening for a bolt head 49 which
is generally similar to bolt head 12. The plate 50 is secured to
outer plate 10 in any preferred manner and secured to plate 50 and
is a housing designated generally 51 comprising top wall 52, bottom
wall 53 and side walls, one of which is shown at 54. Secured to
bolt head 49 is a tail 55 formed with a slot 56 which receives a
guide pin 57 mounted on wall structure 54. Tail 55 is formed with
an end flange 58 which is engaged by one end of an expansion coil
spring 59, the other end of which engages a spring abutment 60
mounted on wall structure 54. A handle 61 is drivably mounted on a
shaft 62 which is pivoted on wall structure 54 and to which is also
drivably connected an actuator 63, the upper end portion of which
engages flange 58 on tail 55. Actuating member 63 is also formed
with a projection 64 which is engaged by one end of a coil spring
65, the other end of which is secured to an anchor 66 secured to
wall structure 54. The tendency of the springs 59 and 65 is to bias
the bolt head 49 into door closing position. As in the case of the
embodiment of FIGS. 1, 2 and 3, the lock set mechanism above
described is another type which is meeting with widespread use.
In accordance with the present invention, a latch bolt stop lever
67 is pivotally mounted on a pin 68 secured to wall structure 54.
At the end remote from pivotal mounting 68, lever 67 is formed with
a notch 69, a tab 70 on the upper side of the notch and an end
portion 71 on the lower side. A fusible pin 72 is received in notch
69 and is secured to wall structure 54.
OPERATION OF SECOND EMBODIMENT
Under normal conditions, latch bolt stop lever 67 assumes the
horizontal position depicted in FIG. 4 in which end portion 71 is
above and clear of bolt head 49 and does not interfere with
movement thereof. Thus, handle 61 may be depressed to retract bolt
head 49 against the influence of springs 59 and 65 or permit it to
be moved into door closing position by these springs.
Should a fire occur, the springs 59 and 65 might become annealed as
above pointed out and lose their holding power. When the
temperature generated by the fire becomes sufficiently high, pin 72
melts and latch bolt stop lever 67 swings downwardly under gravity
action. This downward swinging movement is continued until tab 70
engages the upper surface of bolt head 49 in which position end
portion 71 engages the rear face of bolt head 49 to positively
inhibit retraction of the bolt head and maintain it in door closing
position.
While preferred specific embodiments are herein disclosed, it is to
be clearly understood that the invention is not to be limited to
the exact constructions, mechanisms and materials illustrated and
described because various modifications of these details may be
provided in putting the invention into practice.
* * * * *