Latching mechanism

An aircraft latch utilizes a spindle in combination with an over-center linkage assembly to impart linear motion to a hook member, causing the hook member to either disengage or engage a keeper member on the adjacent structure. The over-center linkage and the spindle are operated by different and independent operations of a handle member. Specifically, the over-center linkage is moved from a stored position, in which the two link members are in end-to-end axial alignment, to a position in which the two link members are no longer in end-to-end axial alignment. This movement is caused by pivoting the handle member from a position in which the longitudinal axis of the handle member is parallel to the axis of the aligned link members, to a second position in which the handle member is pivoted at least ninety degrees. This pivoting motion, which may be accompanied by other actions, such as releasing a trigger, causes the two link members to pivot with respect to each other, or “break”. Once the two link member have broken from the over-center position, the handle is then rotated, causing the spindle to rotate, and thereby imparting a generally linear motion to the hook member, causing the hook to disconnect from the keeper member. The hook member is caused to engage the keeper member by reversing these steps.

BACKGROUND OF THE INVENTION

The invention relates to latches; and more particularly, to aircraft latches. Latches are used on the exterior surfaces of aircraft where it is important that the latch present a flush surface with the aircraft body and indicate when the latch is in a locked or unlocked position. Such latches normally cooperate with a keeper or locking pin on an opposing surface for engaging the latch. It is important that such latches be securely and tightly latched especially when subjected to high vibrations and rattling. This is particularly true when the latch must draw together larger structures over longer distances, and the latch is subjected to higher loads.

SUMMARY OF THE INVENTION

It is an object of this invention to provide an aircraft latch which has the capability of drawing together larger structures over relatively long distances, securely closing and locking so the aircraft latch cannot be opened accidentally during service or the like and which meets requirements for high loading, spatial limitations and meets kinematic requirements. These objects are met by combining an over-center link mechanism with a worm-gear drive mechanism. The apparatus comprises a handle member which both opens the latch but which also drives a gearing system to complete the latch opening process to achieve the large take-up requirements. The presently disclosed device draws larger structures together over longer distances, preloads the system to higher loads, and carries higher loads.

An embodiment of the apparatus utilizes a spindle utilized in connection with over-center linkage to impart linear motion to a hook member, which cause the hook member to either disengage or engage a keeper member on the adjacent structure. The over-center linkage and the spindle are operated by different and independent operations of a handle member. Specifically, the over-center linkage is moved from a closed position, in which the two link members are in end-to-end axial alignment, to a position in which the two link members are no longer in end-to-end axial alignment, by pivoting the handle member from a position in which the longitudinal axis of the handle member is parallel to the axis of the aligned link members, to a second position in which the handle member is pivoted at least ninety degrees. This pivoting motion, which may be accompanied by other actions, such as releasing a trigger, causes the two link members to pivot with respect to each other, or “break”. Once the two link member have broken from the over-center position, the handle is then rotated, causing the spindle to rotate, and thereby imparting a generally linear motion to the hook member, causing the hook to disconnect from the keeper member.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Referring now to the Figures, an embodiment of the disclosed latching mechanism10is depicted inFIG. 1. The latching mechanism10generally comprises two components, being a latch assembly12and a handle member14. Latch assembly12generally comprises a gear housing16, an over-center link assembly18, a latch body20, cam member22, and a spindle24. Referring toFIG. 3, in indicating various directions within the following description, the front of the latching mechanism10is indicated as F, the rear is indicates as R, the bottom is indicated as B, and the top indicated as T. However, it is to be appreciated that the latching mechanism10is operational in any relative position and the above designations are provided for reference purposes only.

Gear housing16comprises a pair of intermeshing bevel gears26,28which are generally mounted at right angles to one another. The first bevel gear26has means for engagement with the spindle24, such as a rearward facing opening30. First bevel gear is mounted within the gear housing16in such a manner as to allow the rotation of the gear, such as mounting the gear within a bearing32. First bevel gear26has means for engaging the spindle24. For example, first bevel gear26may have rearward facing opening30for engaging the front34of spindle24. Rearward facing opening30will be configured in such a manner to provide a positive engagement, such as a hexagonal configuration. Second bevel gear28is attached to housing cover36and is mounted to rotate within bearing38. Second bevel gear28has an upward facing opening40which will, similar to rearward facing opening30, be configured for positive engagement with a male member. Gear housing16further comprises side plates42. Mounted on pins disposed between side plates42are rollers44.

Over-center link assembly18comprises two front links46. Pivotally attached to each front link46is a rear link48such that the front links and rear links are attached in an end-to-end configuration, and front link-rear link assembly is disposed on either side of latch body20. The over-center link assembly18has a first position in which each front link46/rear link48pair are in axial alignment, as shown inFIG. 5. The over-center link assembly18is defined to have a second position which may be any position in which the front link46and rear link48are not in axial alignment. One example of the second position is shown inFIG. 10. InFIG. 10, the over-center link assembly may said to be “broken”, meaning the over-center configuration has been altered.

As best shown inFIG. 5, the latch body20has a front portion50and a rear portion52. The front portion20terminates with a hook member54which engages a keeper (not shown) of an adjacent structure. The rear portion52of the latch body20has a spindle attachment member56, which has internal threads matching the threads of spindle24. As shown in the figures, the spindle attachment member56may be integral to the latch body20. The rear portion52also has means for pivotal attachment of the over-center link assembly18. As shown inFIG. 5, the means for pivotal attachment may comprise integral pin members58which fit into apertures60of rear link48. However, it is to be appreciated that other means for pivotal attachment may be utilized, such as openings in spindle attachment member56which receive male members extending from rear link48. Latch body20further comprises integral pins62which are engaged by slot64in trigger66. Trigger66is biased in the closed position by biasing means, such as a torsion spring (not shown). Safety68is mounted at the front of latch body20with rivet70. Safety68is biased by a torsion spring (not shown) which rotates safety into the opening of hook member54unless handle member14is in the downward (closed) position, as shown inFIGS. 1-3.

Cam member22is attached by mounting bushing72to front links46and to gear housing16. In addition, handle member14is pivotally attached to the upper side of cam member22with pin74. Trigger66is pivotally attached to the back of cam member22. Cam member22further comprises guide plate76which has an opening78which, cam member22is rotated into the opening position by handle member14, will provide access to the upward facing opening40in second bevel gear28.

Spindle24comprises a threaded shaft. A single start class 3G Acme thread per ASME/BSNI B1.5-1988 is an acceptable thread. Spindle24has a rear end80which threads through the spindle attachment member56of the latch body. Stop pin82is attached to the rear end80. Spindle24has a front34which is operationally attached to the handle member14with a gear means, such that rotation of the handle member causes rotation of the spindle. For example, front34may comprise a male extension which is configured to lockingly engage rearward facing opening30of first bevel gear26. Once the over-center link assembly18has been “broken” from an axially aligned configuration from rotation of the handle member14as described in greater detail below, rotation of the spindle24causes the front links46and rear links48to collapse together as spindle attachment member56is pulled forward on the threads of the spindle, such that latch body20, including hook member54, is moved forward, thereby unlocking the hook member from the keeper Likewise, rotation of the handle member14in the opposite direction moves the hook member54of the latch body to move back to the locked position.

FIG. 6shows an exploded view of handle member14. Handle member14comprises handle84and inner tube86which collapses inside of the handle when the handle member14is in the locked position as shown inFIGS. 1-3. An end of inner tube86is attached to bracket90by the insertion of bushing92into end88. Hex rod94is partially inserted within rod tube96, with rod collar98stopped and retained within the rod tube by bushing100, such that portions of the hex rod will slide into and out of the rod tube without the hex rod coming completely out of the rod tube. Bushing100has a hexagonal profile which engages hex rod94when rod tube96is rotated. Handle84is attached to collar102. Collar102slides over the end88of inner tube86and is held in place by lock rings until manually pulled free by an operator, causing handle84to telescope outward. When handle84is telescoped outwardly, rod tube96inside of handle84telescopes outwardly as well.

Rod tube96is held within handle84by connector104. Connector104has an outer ring106which abuts the end of handle84. Connector104comprises end108which is attached to the end of rod tube96. End108rotates within outer ring106, allowing rotary motion to be imparted to rod tube96by attachment of a tool to the exposed end of connector104protruding from handle84. Rotation of rod tube96causes hex rod94to rotate as well. Hex rod94is biased forward within rod tube96by spring108. Hex rod94has a hex end110. When the handle14is unlocked and pivoted into the correct position, hex end110engages the upward facing opening40of second bevel gear28. It is to be appreciated that while hexagonal profiles are described for the locking engagement of various components, other locking profiles may be utilized as well without detracting from the functionality of the apparatus.

FIGS. 7 through 11depict the sequence of opening an embodiment of the disclosed latching mechanism10.FIG. 7shows an embodiment of the latching mechanism10in the closed position, with the handle member14in stored position. As shown inFIG. 7, when the latching mechanism10is in the closed position, the front links46and the back links48of the over-center link assembly18are in axial alignment. In this closed position of the latching mechanism10, the handle member14may be said to be in the stored position, i.e., the position in which it will travel. In the stored position, the axis of the handle member14is in parallel alignment with the axis of the front link46and the back link48. Handle member14is not extended when the latch mechanism10is in the closed position.

FIG. 8shows the first step in the opening sequence for this embodiment of the latch mechanism10. The first step is to pivot handle member14greater than 90 degrees from its closed position shown inFIG. 7, such that the handle member14is moved from the stored position to an unstored position. The inventor herein has found that a pivot angle of 125 degrees in the handle member14is acceptable for the embodiment depicted inFIG. 7.FIG. 9shows the next step in the opening sequence, in which handle84is pulled downward, causing it to telescope from inner tube86. Once the handle member14has been extended, trigger66is rotated, causing it to release from integral pins62.

The next step in the opening sequence is depicted inFIG. 10. Handle member14is pivoted toward its stored position, but is stopped at a position which is approximately at 90 degrees from its stored position. As shown inFIG. 10, this action causes the cam member22to rotate, breaking the axial alignment of front link46and rear link48. Once the over-center link has been broken in this manner, hex end110of hex rod94aligns with the opening40of second bevel gear28, and is urged into the opening by spring108or other biasing means.

Once hex end110has seated in opening40, a tool is attached to the exposed end of connector104protruding from handle84, and rotary motion, usually clockwise, applied to the exposed end of the connector. The rotary motion causes the rotation of rod tube96and hex rod94and causing the rotation of second bevel gear28. Second bevel gear28causes the rotation of first bevel gear26, which in turn causes the rotation of spindle24. Rotation of the spindle24pulls the latch body20forward on the threads of the spindle, until the latch body20is fully forward. As best shown inFIG. 4, latch body20may extend through the lower portion of gear housing16, between side plates42, and supported on rollers44. As shown inFIG. 11, an embodiment of the latch mechanism10may comprise a shoulder112on each rear link48which, when the latch body is fully forward, abuts extensions114on cam member22, thereby imposing a positive indication that the latch body20is fully forward.

To close the latch mechanism10, a tool is again attached to the exposed end of connector104and rotary motion again applied, in the opposite direction as for opening the latch, so the rotary motion will usually be counter-clockwise. Rotary motion is continued to be applied until the spindle attachment member56reaches the end of the threads of spindle24at stop pin82, at which point the latch mechanism10is in the configuration depicted inFIG. 12. At this point, handle member14is pivoted backward to the position indicated inFIG. 13, thereby pushing front link46and rear link48back into axial alignment. Rear link48may comprise stop member116which prevents over rotation of front link46. Once handle member14is pivoted into the position shown inFIG. 13, trigger66locks automatically. From the position shown inFIG. 13, the handle84is pushed over inner tube86and the handle member14is pivoted to the stored position shown inFIG. 14, at which point the hook member54will have re-engaged the keeper (not shown).

Latch mechanism10is fabricated from such materials as accepted within the aircraft industry, including high strength light weight alloy materials, and heat treated as required. The dimensions for each of the components of the latch mechanism10will be determined upon load requirements and spatial considerations. Fabricated components are to be inspected according to the appropriate inspection protocol per the applicable aircraft standards.

While the above is a description of various embodiments of the present invention, further modifications may be employed without departing from the spirit and scope of the present invention. Thus the scope of the invention should not be limited according to these factors, but according to the following appended claims.