Abstract:
An intruder-resistant latch useful for latching an aircraft flight deck door includes a damper for reducing noise while the latch is in operation. The latch also includes a driver member having coated pins that reduce noise while the latch is in operation.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims the benefit of U.S. Provisional Application No. 60/393,594, filed Jul. 3, 2002, which is hereby incorporated by reference in its entirety. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention relates generally to aircraft door latches and, more particularly, to an intruder-resistant aircraft door latch having a damper for reducing noise while the door is being operated.  
         BACKGROUND OF THE INVENTION  
         [0003]    There is presently a heightened interest to provide for the personal safety of aircraft passengers and flight crews during air travel. Thus it is desirable to configure flight deck doors and door latches on aircraft so as to minimize opportunities for unauthorized persons to enter an aircraft flight deck. In order to meet Federal Aviation Administration (FAA) regulations for commercial aircraft, cockpit doors, including latches and structures surrounding such doors, should be strong enough to withstand ballistic impact and unwanted intruder entry.  
           [0004]    Door structures that meet such specifications, however, tend to be heavy and to produce undesirable noise during operation. For example, when such a door is closed, the sound of a latch bolt snapping into place to bolt the door can be sufficiently loud to distract crew members who are operating the aircraft. Such noises also have a tendency to awaken crew members sleeping in nearby crew rest areas. It would be desirable, then, to provide cockpit door latches that are resistant to intruders and ballistic impact but are quiet during operation.  
         SUMMARY OF THE INVENTION  
         [0005]    The present invention, in one preferred embodiment, is directed to an intruder-resistant latch useful for latching an aircraft flight deck door. The latch includes a damper for reducing noise while the door is being operated. The latch also includes a driver member having pins coated, for example, with a urethane coating that reduces noise while the latch is in operation. The latch allows a flight deck door to be operated with minimal disturbance to a flight crew at work and/or crew members who may be resting. The latch is fabricated of ballistic impact-resistant material(s).  
           [0006]    Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:  
         [0008]    [0008]FIG. 1 is an exploded perspective of an embodiment of a door latch according to principles of the present invention;  
         [0009]    [0009]FIG. 2 is a cross-sectional view of the door latch shown in FIG. 1;  
         [0010]    [0010]FIG. 3 is an exploded perspective of the latch shown in FIG. 1;  
         [0011]    [0011]FIG. 4 is a longitudinal view of the latch shown in FIG. 1; and  
         [0012]    [0012]FIG. 5 is a frontal view of the latch shown in FIG. 1. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0013]    The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. Embodiments of the present invention are described herein relative to an aircraft cockpit door. Embodiments are described as having one handle so as to allow such a door to be opened only from inside the cockpit. The invention, however, is not so limited. Embodiments also are contemplated having more than one handle and/or configured for use with openings other than cockpit doors.  
         [0014]    An embodiment of a door latch useful for latching an aircraft cockpit door is indicated generally by reference number  10  in FIG. 1. The latch  10  includes a latch body  14  having a hollow  18  for accommodating a bolt member  22 . The latch body  14  and bolt member  22  are installed together in a recess at an edge of the door (not shown), as is widely known. The bolt member  22  can be moved relative to the latch body  14  and the door as further described below. Movement of the bolt member  22  allows a bolt  26  extending from a proximal wall  30  of the bolt member  22  to be extended through a slot  34  in a proximal wall  38  of the latch body  14  and into a bolt receptacle or strike in the door frame (not shown). The terms “proximal” and “distal” are used herein with reference to a door edge at which the latch  10  is configured to be installed.  
         [0015]    The latch body hollow  18  is defined generally by the proximal wall  38 , a driver mount  40  extending proximally from a distal wall  42 , an upper wall  46 , and a lower wall  50  extending from a plate  54 . An upper wall  58  and lower wall  62  of the bolt member  22  extend distally from the proximal wall  30  and terminate in a pair of abutments  66   a  and  66   b . A plate  70  extending from the proximal, upper and lower walls  30 ,  58  and  62  has a slot  74  defined between the abutments  66  for accommodating a driver member as further described below. The upper and lower walls  58  and  62 , abutments  66  and slotted plate  70  together form two opposed arms  78   a  and  78   b  of the bolt member. The bolt  26  has a beveled tip  82 .  
         [0016]    A door handle  86  is mounted, for example, on the flight deck side of the door, over a decorative escutcheon plate  88 . The handle  86  is fixedly connected to a shaft  92 . The shaft  92  extends rotatably through a hole  96  in the escutcheon plate  88 , through a partial section (not shown) of the door, and into the driver mount  40  via a hole  98 . An end groove  102  of the shaft  92  is fixedly connected to a driver member  106  via a tongue  108 . The driver member  106  has a pair of arms  110   a  and  110   b  that include a pair of pins  112 . The pins are preferably integral to the driver member  106  and padded with a urethane or plastic coating. Other coatings comparably effective for sound dampening may be used. The driver and pins shall be further described below.  
         [0017]    A damper member  118  is housed in a recess  122  in the latch body upper wall  46 . The damper member  118  includes a base  124  shaped to fit the recess  122 , and a viscous damper  128 . The damper is, for example, a rotary damper, part number ACE-RD301, fabricated by Ace Controls Inc. of Farmington Hills, Mich., and contains silicone grease. Other dampers could be used so as to provide damping action as described further below. A lever  132  is mounted on a movable shaft  134  extending from the damper  128 . As shall be described more clearly below, the lever  132  extends generally downwardly into a slot  138  in the upper wall  58  of the bolt member  22 .  
         [0018]    The bolt member abutments  66  are disposed against a pair of generally parallel springs  142   a  and  142   b  lodged in channels  144  terminating at the distal wall  42  of the latch body as further described below. A cover  146  covers the latch body  14 . The cover  146 , bolt member  22 , springs  142 , driver member  106  and pins  112  integral to the driver member  106  are fabricated, for example, of heat treated stainless steel having a strength of about 190,000 pounds per square inch. In other embodiments, other ballistic-impact-resistant materials could be used. The handle  86 , escutcheon plate  88  and latch body  14  are fabricated, for example, of aluminum. The damper  128  and lever  132  are fabricated, for example, of plastic.  
         [0019]    [0019]FIG. 2 is a cross sectional view of the latch  10  in a normal state, i.e. wherein the bolt  26  is extended relative to the latch body  14  and the door. The springs  142  are slightly compressed in the channels  144  so as to press the bolt member  22  against the proximal wall  38  of the latch body  14 . The driver pins  112  rest upon the bolt member arms  78 . The damper lever  132  extends through the slot  138  in the bolt member upper wall  58 , generally in the direction of the bolt  26 .  
         [0020]    [0020]FIG. 3 is an exploded perspective view of the latch  10 . FIG. 4 is a longitudinal view of the latch  10 . FIG. 5 is a frontal view of the latch  10 .  
         [0021]    To close the door, a user preferably pushes the door to a closed position without turning the handle  86 . The beveled tip  82  of the bolt thus is pressed, for example, against a strike plate (not shown) on the door frame, as known in the art. The door closes as the strike plate causes the bolt member  22  to compress the springs  142 , and the bolt  26  retracts into the latch body  14 . The damper lever  132  is pushed distally by the moving bolt member  22 , and the damper  128  thus is activated to slow the movement of the lever  132  and the bolt member  22 . As the bolt member  22  is pushed toward the springs  142 , the urethane coating on the driver pins  112  tends to dampen noise generated by contact between the pins and the plate  70  as the plate  70  is shifted distally underneath the pins  112 .  
         [0022]    As the door is closed, the slot  34  comes into alignment with the bolt receptacle, e.g., an electrically powered strike. The springs  142  push the bolt  26  through the slot  34  into the receptacle as the springs return to their normal state. As the bolt member  26  is pushed by the springs, the damper  128 , via the lever  132 , retards the proximal movement of the bolt member  22 . The urethane coating on the pins  112  tends to dampen noise generated by the bolt member arms  78  moving beneath the driver pins  112 . The user alternatively can move the door to a closed position while turning the handle and moving the door in the desired direction. Turning the handle activates the driver member  106 , as shall now be described.  
         [0023]    To open the door, the user rotates the handle  86  in either a clockwise or counterclockwise direction while moving the door toward an open position. As the driver member  106  is rotated via the shaft  92 , one of the driver arms  110  is pressed against a corresponding abutment  66 . For example, as the driver member is rotated clockwise as shown in FIG. 2, the lower driver arm  110   b  is pushed against the lower abutment  66   b . As the lower abutment is pushed, the springs  142  are compressed. As the bolt member  22  moves distally, the bolt  26  is retracted from the receptacle, and the door can be moved to an open position.  
         [0024]    The two springs  142  provide a spring force that can be felt by a user while operating the latch  10 . Should one of the springs  142  fail to operate in the intended manner such that the spring force is reduced, the difference in the spring force also can be felt by the user while operating the latch. Thus a need for repair can be determined before the latch  10  becomes inoperable.  
         [0025]    Although the above described latch is ballistic-impact-resistant, it closes quietly, even when installed on a door representing a load as heavy as 2,000 pounds. As the door is closed, the damper retards the springing of the bolt member while the coating on the driver pins reduces noise. Thus the latch can be operated without unduly distracting the flight crew and without disturbing nearby sleeping passengers and/or resting crew members. Because the above latch can be retrofitted onto existing aircraft cockpit doors, costs of configuring aircraft to meet safety specifications can be reduced.  
         [0026]    The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.