GB2170548A

GB2170548A - Latch safety lock

Info

Publication number: GB2170548A
Application number: GB08601379A
Authority: GB
Inventors: Warren C Bross
Original assignee: Rexnord Inc
Current assignee: Rexnord Inc
Priority date: 1985-01-31
Filing date: 1986-01-21
Publication date: 1986-08-06
Also published as: FR2576960B3; DE8601523U1; FR2576960A3; GB8601379D0

Abstract

A safety lock for a tension latch is provided which positively locks the latch in a closed position relative to the panel in which the latch is installed and allows the user to visually determine when the lock is in its locked position. The lock includes a sliding member (16), a guide (17), and an actuating mechanism for the sliding member (16). The guide (17) is mounted to the underside of the latch handle (15). The actuating mechanism comprises a push-button (30) spring biased by a spring washer (31). The actuating mechanism extends through the latch handle (15), as well as the guide (17). A portion (32) of the button (30) engages the sliding member (16). When the actuating mechanism is in its normal or first position, the sliding member (16) is in a retracted position relative to the latch handle (15) and panel and thus does not positively lock the latch closed. When the actuating mechanism is moved into its second position, such movement simultaneously causes the sliding member (16) to move to its extended position resulting in a portion of the member underlying the panel adjacent the latch handle (15). In this position the sliding member (16) positively locks the latch against outward movement from the panel. <IMAGE>

Description

SPECIFICATION Latch safety lock The present invention relates to latches and in particular to a safety lock mechanism which maintains the latch in a secured, closed condition relative to the panel in which the latch is installed.

In the aircraft industry tension latches are required to secure access panels and engine cowls on aircraft. Despite their usefulness, such latches have caused a number of recurring problems which, until the present invention, were unsolved over a period of years.

The problems centered around inadvertent opening or unlocking of the tension latches which subjected the aircraft to possible loss of the panel or cowl, as well as to severe, costly damage. For example, on certain engine cowl applications, latches are installed in relatively close proximity to the aircraft's propeller blades. If the latch swings outward from its flushed locked or closed position, it is subject to being hit by the rotating blades causing damage as well as endangering the safety of the aircraft in flight.

Attempts have been made to provide a safety lock for such latches but such attempts have been unsuccessful and not well received by the industry. The industry does not wish to modify or rework its existing aircraft design in order to accommodate complex or bulky safety lock mechanisms for the latches for a variety of reasons. Thus the present invention has been developed to meet the specific design demands of the industry while at the same time successfully accomplishing the goal of providing a safety lock which is adapted for installation on existing latch handles. Further, the present invention satisfies another need of the industry which is the capability of visually determining when and if the safety lock is in its locked position.

The present invention is a safety lock mechanism which prevents aircraft latches from inadvertently opening or swinging outward from the latch's normally flush installed position. Three basic components are provided to achieve the desired results, i.e., a sliding member which positively engages beneath the panel surface adjacent to the installed latch, a guide for directing the movement of the sliding member between locked and unlocked positions, and a mechanism for actuating movement of the sliding member relative to the latch.

The invention is installed on a portion of the latch handle with the actuating mechanism clearly visible to the operator for convenient use, as well as visual inspection. Preferably the sliding member is relatively flat and the guide is secured directly to the underside of the latch handle. The latch handle is provided with an opening directly above the guide for installation of the actuating mechanism. The actuating mechanism may be an eccentric cam arrangement or a stepped, spring biased button. Regardless of the particular selected structure, the invention is inexpensive to manufacture as it has only a few parts, and it is easily assembled for quick installation and reliable operation.

These and other details and advantages of the present invention are explained further in the detailed description which follows.

A more thorough understanding of the present invention will be gained by reading the following description of the preferred embodiments with reference to the accompanying drawings in which: Figure 1 is an exploded view in perspective of a first embodiment of the present invention.

Figure 2 is a top plan view of the first embodiment shown installed and in an unlocked condition.

Figure 3 is a top plan view of the first embodiment shown installed and in a locked condition relative to the latch and the panel.

Figure 4 is a side elevational view of what is shown in Fig. 3.

Figure 5 is an exploded view in perspective of a second embodiment of the present invention.

Figure 6 is a top plan view of the second embodiment shown installed and in an unlocked condition.

Figure 7 is a bottom plan view of what is shown in Fig. 6.

Figure 8 is a top plan view of the second embodiment shown installed and in a locked condition.

Figure 9 is a bottom plan view of what is shown in Fig. 8.

Figure 10 is a side elevational view of what is shown in Fig. 8.

In the drawings the illustrated latch is a conventional tension latch typical of a type of latch to which the present invention is directed. For reader reference the illustrated latch is completely described in U.S. Patent 3,259,411 for a "Drawhook Toggle Latch" which issued July 5, 1966, to E. G. Griffiths.

Turning now to Fig. 1, a first embodiment of the present invention may be described.

The invention is installed at one end of a latch handle 15. The three basic components of the invention are: a sliding member or tongue 16, a guide means 1 7 for directing the movement of the sliding member 16, and an actuating mechanism. In the first embodiment the actuating mechanism is embodied in a stepped button and spring washer arrangement.

The sliding member 16 is a flat, rectangular shaped piece of metal having a top surface 18, a bottom surface 19 and a centrally located opening 20 therein. The opening 20 is of a size and shape comparable to a portion of the stepped button to be explained herein after. The guide means is a C-shaped piece of metal of a size to accommodate the sliding member therein for free movement of the sliding member into and out of the guide 17. The guide 17 has a top surface 21 and a- pair of downwardly extending side walls 22, 23, each of which terminates in a flange 24, 25, respectively, which extends a predetermined distance inwardly towards the other flange and substantially parallel to the top surface 21 of the guide. The distance between the bottom side of the top surface 21 and the top side of the flanges 24, 25 cannot be less than the thickness of the sliding member 16.A sufficient portion of the guide top surface 21 is cut away to provide an opening 26 for installation of the actuating mechanism. Also provided on the top surface 21 are a pair of oppositely positioned rivet holes 27, 28 to facilitate the securing of the guide 17 to the underside of the latch handle 15.

The actuating mechanism comprises a button 30 and a spring washer 31. In the illustrated embodiment the button 30 is a threestep configuration with a downwardly extending lug 32. The uppermost step 33 of the button has a first diameter. A screw driver slot 34 is provided, allowing the use of a tool to slide the button 31. The second or intermediate step 35 has a second diameter greater than the diameter of the uppermost step 33. The lowermost or bottom step 36 has a diameter greater than that of the intermediate step 35. From the underside of the lowermost step 36 the lug 32 extends a predetermined distance and preferably has a square cross-section. The lug 32 must be long enough to be received in the sliding member opening 20. The spring washer 31 is of contentional design and has an outer diameter substantially equal to the diameter of the button lowermost step 36.A centrally located opening 38 is provided in the washer 37 for passage of the button lug 32 therethrough. It will be appreciated by those skilled in the art that a conventional helical spring may be used rather than a spring washer.

The latch handle 15 has a surface portion 40 which is provided with a pair of partially overlapping openings 41, 42. The first or rearward opening 41 has a diameter corresponding to the diameter of the button uppermost step 33. The second or forward opening 42 has a diameter corresponding to the diameter of the intermediate step 35. Thus, the opening 41 allows only the uppermost step 33 of the button 31 to protrude therethrough while the other adjacent opening 42 allows both the uppermost and intermediate button steps 33, 35 to protrude therethrough, but prevents the lowermost step 36 from doing so. The latch handle 15 is provided with an opposing pair of rivet holes 43, 44 which are located so as to be aligned with the rivet holes 27, 28, respectively, in the guide 17.

To install the first embodiment the spring washer 37 is slipped onto the lug 32 of the button 31 and the button is then inserted into the opening 41 with the uppermost step protruding therethrough and above the top surface 40 of the handle. The sliding member 16 having been inserted into the guide 17, the button lug 32 may then be inserted into the sliding member opening 20 and the rivet holdes 27, 28 of the guide aligned with the rivet holes 43, 44, respectively, of the latch handle 15. A conventional rivet 45 is then installed in aligned opening 27, 43. To allow a second rivet 46 to be installed in aligned openings 28, 44 a second opening 47 is provided in the sliding member of sufficient size to allow the rivet 46 to pass therethrough without securing the sliding member 16 to the guide 17.The resulting installed mechanism appears as shown in Fig. 2 and is in an unlocked or retracted state. This embodiment may be modified to eliminate the second opening 47 in the sliding member in the following manner. The guide 17 may first be riveted to the handle. The sliding member 16 is then inserted into the guide 17. The lowermost step 36 may be eliminated from the button. The button lug 32 is formed with a circular cross-section. The modified button and underlying spring are positioned in place, and the button is riveted to the sliding member 16 through a circular opening rather than the square opening 20.

To use the safety lock mechanism of the first embodiment, the user need only apply a forward sliding force to the button 31. A sufficient force moves the button out of its first position in the smaller opening 41 forward into the larger opening 42. The forward movement of the button 31 simultaneously causes the lug 32 to move the sliding member 16 forwardly. When the button 31 is situated completely in the larger opening 42 it may be released. The upwardly biased button 31 moves upwardly by spring force and is held in this position by the lowermost step 36 being pressed into contact with the underside of the latch handle with the uppermost and intermediate button steps 33, 35 protruding through the opening. (See Figs. 3 and 4). Thus, the safety lock is now in its locked position with a portion of the sliding member protruding or extending forward of the latch handle so as to lie beneath the immediately adjacent portion 48 of the panel or cowl. It is this extending portion which prevents the latch from inadverently opening and swinging outwardly from its desired flush position in the panel. The user may readily determine if the safety lock is engaged or not with the panel by merely noting whether the button is in the smaller, rearward opening 41 or in the larger, forward opening 42. Accordingly, all of the needs of the aircraft industry with respect to the problems of maintaining certain tension latches in a closed, flush position are answered by the present invention and its three basic components.

A second embodiment of the present invention is illustrated in Figs 5-10. As with the first embodiment all three basic components are present, and the latch handle is identical to that shown in Figs. 1-4. In the second embodiment an eccentric cam and spring-finger are used for the actuating mechanism. The guide and the sliding member are modified accordingly.

In Fig. 5 the sliding member 50 is formed from a relatively flat, rectangular piece of metal. The member has a top surface 51 as well as a bottom surface 52. In the rearward half of the sliding member 50 a portion of the member is cut out to leave a finger 53 of material extending within the cut out area and integral with the remaining portion of the sliding member. At the tip or forward end 54 of the finger along the top side 55 a protrusion 56 is provided for reasons to be explained hereinafter. Forward of the finger a short distance a transverse slot 57 is cut into the member. The slot 57 is located closer to one edge 58 of the member than to the opposing edge 59.

The guide means 60 for containing the sliding member and directing its movement between a locked and an unlocked position is, as in the first embodiment, a substantially Cshaped piece of metal having a top surface 61 and a pair of opposing side walls 62, 63 extending downwardly from the top surface 61.

Each side wall 62, 63 terminates in a flange 64, 65, respectively, directed towards each other and lying in a plane parallel to the top surface 61. Again, the distance between the top surface 61 and the flanges 64, 65 must be greater than the thickness of the sliding member 50 to allow movement of the sliding member 50 relative to the guide 60. On the top surface 61 a circular opening 66 is provided. The opening 66 is situated directly above the slot 57 and the spring-finger protrusion 56 when the sliding member is within the guide 60. To the rear of the opening 60 a rivet hole 67 is provided for securing the guide to the underside of the latch handle 70.

A like rivet hole 68 is provided in the latch handle at a location such that the rivet holes 67, 68 may be aligned and the guide fixed to the latch handle by means of a rivet 64 of conventional design.

The sliding member actuator for this invention is a button 72. However, instead of a spring-biased stepped button, the button 72 is provided with an eccentric cam 73 and detent 74. The button 72 has a head portion 75 of given diameter and a body portion 76 extending below the head portion 75. The body portion has an outer diameter which is less than the outer diameter of the head portion but not greater than the diameter of the opening 66 in the guide 60. The button 72 includes a bore into which the cam or plug 73 is installed to provide the eccentric cam for this embodiment. The plug 73 includes a lowermost end having a head 77 which protrudes from the bottom of the button body portion 76. The plug 73 has a shaft outer diameter which does not exceed the width of the sliding member slot 57. The outer diameter of the head 77, however, is greater than the width of the slot 57.Opposite the bore in the button a recessed area or detent 74 is provided for receiving the sliding member protrusion 56 therein when the invention is in a locked position. To assist the user a screw driver slot 78 is provided in the head portion 75 of the button which allows rotation of the button.

For installation purposes the larch handle 70 is provided with an opening 79 which is substantially equal in size to the opening 66 in the guide and located so as to be aligned with the opening 66 when the guide 60 is secured to the handle.

To install the second embodiment of the invention the button 72 is inserted from above the handle into the openings 79 and 66. The guide rivet hole 67 is aligned with the handle rivet hole 68 and the two are riveted together. The sliding member 50 is then inserted into the guide 60 and the button is turned until the detent 74 is on the opposite side of the slot 57 from the finger protrusion 56 and the bore in the button is aligned with the slot 57. After the proper alignments have been achieved, the plug 73 is fixed by any conventional manner within the bore leaving the head 77 protruding beyond the slot 57.

Turning now to Figs. 6-10, the locked and unlocked conditions of a second embodiment may be appreciated. After the lock is installed and in its unlocked condition, it will appear as illustrated in Figs. 6 and 7. To place the safety lock in its locked condition relative to the panel 80 the user merely turns the button 72 approximately 180 degrees clockwise. The rotation of the button 72 causes the cam, i.e., plug and head 73, 77, to move relative to the slot 57 which movement is in turn translated into forward linear movement of the sliding member 51. Accordingly, at the conclusion of the approximate one-half turn, the detent 74 in the bottom of the button 72 is situated over the finger protrusion 56 at which point the protrusion springs up and is caught in the detent and maintains the safety locked in a locked condition.Figs. 8-10 illustrate the appearance of the installed second embodiment in the locked condition. As with the first embodiment, only a portion of the sliding member extends beneath the panel portion 80. This amount, however, is sufficient to prevent the latch from inadvertently opening outwardly. To unlock the safety lock the user need only rotate the button approximately 180 degrees counterclockwise and thus moves the protrusion 56 out of the detent 74. The but ton and sliding member may then return to their unlocked positions relative to each other as shown in Figs. 6 and 7.

From the foregoing it can be appreciated that the present invention in both embodiments provides a reliable safety lock for panel latches. The invention positively locks the latch so that it does not inadvertently open as a result of normal aircraft operating and vibration forces. Further, the invention provides the user with visual indicators so that the user may readily appreciate when the safety lock is in the locked or unlocked condition. The aircraft panel need not be modified to accommodate the invention. The latch does not require any significant modification. The user must merely provide an appropriate opening in the latch handle for receiving the actuator button of the invention. The invention has low manufacturing costs because of the few number of parts which must be used in the invention. It is easy to install and equally foolproof to use.

Of course, modifications in structure from what is shown and described for the two embodiments may be possible to those skilled in the art. Thus, the invention is limited in scope only by the claims which follow.

Claims

1. A device for positively locking a tension latch relative to an opening in which the latch is installed and providing visual inspection as to the locked or unlocked condition of the latch, said device comprising: a sliding member having a first retracted position and a second extended position; guide means for containing said sliding member during movement of said sliding member between said first and said second positions, said guide means being adapted for securement to a portion of a latch; and means for actuating said sliding member for movement of said sliding member relative to the latch, said actuating means being operatively connected to said sliding member and having a first position corresponding to said sliding member first position and a second position corresponding to said sliding member second position, said actuating means including means for manually moving said sliding member from said first position to said second position whereby when said sliding member is in said second position the latch is positively maintained in a closed position as a result of said sliding member engaging an underlying surface of the panel containing the latch.

2. The device of Claim 1 wherein said actuating means comprises a spring-biased, stepped button, said button having a lowermost portion which cooperatively engages said sliding member and an uppermost portion which cooperatively engages the latch when said actuating means is in said first and second positions.

3. The device of Claim 1 wherein said actuating means comprises a button having an eccentric cam therein and said sliding member includes a portion with a slot therein for receiving said eccentric cam, said button being rotatable between said actuating means first and second positions with said slot captivating said eccentric cam and said sliding member being moved between said first retracted position and said second extended position by said button rotation.

4. A device for positively locking a tension latch relative to an opening in which the latch is installed and providing visual inspection as to the locked or unlocked condition of the latch, said device comprising: a sliding member having a first retracted position and a second extended position; guide means for containing said sliding member during movement of said sliding member between said first and said second positions, said guide means being adapted for securement to an installed latch handle; and means for actuating said sliding member for movement of said sliding member relative to the latch, said actuating means inciuding a button positioned so as to engage said sliding member and the latch, and means for biasing said button in a first position when said sliding member is in said respective first position, with the latch being adapted to include an opening in a portion thereof for confining said button in said first position and in a said second position whereby movement of said button between said positions causes simultaneous movement of said sliding member from said retracted position into said extended position with said sliding member engaging a portion of an adjacent panel when in said extended position positively locking the latch.

5. A device for positively locking a tension latch relative to an opening in which the latch is installed and providing visual inspection as to the locked or unlocked condition of the latch, said device comprising: a sliding member having a first retracted position, a second extended position, and a portion having a transverse opening therein; guide means for containing said sliding member during movement of said sliding member between said first and said second positions, said guide means being adapted for securement to a portion of an installed latch; and means for actuating said sliding member for movement of said sliding member relative to the latch, said actuating means including a button having an upper head portion, a lower body portion, and cam means for engaging said sliding member within said transverse opening, said button extending through the latch and said guide means and constructed and arranged for rotational movement relative thereto, said cam means having a first position and a second position within said transverse slot with movement of said cam means being effected by rotation of said button, when said cam means is in said first position said sliding member is in said first retracted position, when said cam means is moved into said second position said sliding member is moved into said second extended position with said sliding member engaging a portion of an adjacent panel and thereby positively locking the latch relative to the panel.

6. The device of Claim 5 wherein said sliding member includes a finger member adjacent said transverse slot, said finger member including a free end portion having a protrusion thereon, with said button further including a detent constructed and arranged to receive and securley retain said protrusion therein when said cam means is in said second position and said sliding member is in said extended position.