Abstract:
A rotary latch including a hook arm joined to a drive sleeve having an end flush with a surrounding surface, the sleeve having a tool receiving socket; the socket also receiving a reciprocal signal shaft occupying a flush position when the latch is secured but automatically movable to an extended position or retracted position to signal that the latch is not secured.

Description:
BACKGROUND AND SUMMARY 
     Flush type rotationally driven latches are used extensively on aircraft; however, as the driving means remains in a flush or recessed condition, whether or not the latch is in its locked or unlocked position, observation of the exposed portions of the latch gives no indication as to the condition of the latch. 
     The present invention and the following copending applications are directed to rotary latches which offer solutions to this problem. 
     FLUSH TYPE ROTARY DRIVE FOR LATCHES 
     Inventor: L. Richard Poe 
     Ser. No. 856,504 filed Dec. 1, 1977 
     ROTARY LATCH AND METHOD OF OPERATION 
     Inventor: L. Richard Poe; William R. Bourne 
     Ser. No. 11,193 filed Feb. 12, 1979 
     More particularly, the present invention is summarized in the following objects: 
     First, to provide a rotary latch having a hook arm and an integral drive sleeve, the sleeve having an outer end disposed flush with a surrounding surface and a tool receiving socket, the socket having a reciprocable signal shaft occupying a position flush with the outer end of the drive sleeve when the latch is locked, one embodiment occupying an extended position and another embodiment occupying a retracted position when the latch is not secured, the position of the signal shaft being readily observable. 
     Second, to provide a rotary latch wherein the signal shaft is secured in its flush condition or its signal position against release due to shock or vibration. 
     Third, to provide a rotary latch of the type indicated in the other objects, wherein the signal shaft is secured against rotation with respect to the body of the latch, and the drive sleeve is provided with a captive ball or roller movable to lock the signal shaft in its flush position or signal position. 
     Other and additional objectives will become apparent upon a reading of the entire specification, drawings and claims. 
    
    
     BRIEF DESCRIPTION OF THE FIGURES 
     FIG. 1 is a plan view of the rotary latch shown secured to a keeper loop. 
     FIG. 2 is a longitudinal sectional view of the latch taken through 2--2 of FIG. 1 showing the latch in its secured position. 
     FIG. 3 is a longitudinal sectional view corresponding to FIG. 2, showing the latch in its released position. 
     FIG. 4 is a fragmentary longitudinal sectional view, corresponding to FIG. 2, showing the latch on initial depression of the signal shaft from its flush position. 
     FIG. 5 is a fragmentary longitudinal sectional view, corresponding to FIG. 2, showing the signal shaft fully depressed by a tool prior to rotation to release the hook latch. 
     FIG. 6 is a fragmentary sectional view taken through 6--6 of FIG. 1, showing means for restraining the signal shaft against rotation. 
     FIG. 7 is a fragmentary transverse sectional view also showing the restraining means. 
     FIG. 8 is an end view of a modified signal shaft wherein the shaft occupies a depressed position as a signal that the latch is in its released position. 
     FIG. 9 is a side view thereof, with adjacent portions of the rotary latch shown fragmentarily. 
     FIG. 10 is a fragmentary longitudinal sectional view, taken through 10--10 of FIG. 11, showing a modified signal shaft utilizing a cylindrical roller. 
     FIG. 11 is a transverse sectional view taken through 11--11 of FIG. 10. 
     FIG. 12 is an end view of the signal shaft as modified to utilize a roller. 
     FIGS. 13 and 14 are side views of the modified signal shaft. 
    
    
     DETAILED DESCRIPTION 
     Referring to FIGS. 1 through 7, the rotary latch here illustrated includes a circular housing 1 having a flat cylindrical chamber 2 from which extends a sleeve 3. The chamber is provided with a cover plate 4. Mounting means 5 is provided to secure the rotary latch to an appropriate structure, not shown, having a surface flush with the extremity of the sleeve 3. The housing 1 and cover plate 4 have a radial keeper slot 6 which receives a keeper 7. 
     The chamber 2 receives a latch unit 8 having a drive sleeve 9 journalled in the sleeve 3 which is integrally joined by a connecting web 10 to an arcuate latch arm 11 conforming to the periphery of the chamber 2. The latch arm 11 tapers toward its extremity 12 which is dimensioned to receive the keeper 7 and as the latch arm is rotated, the keeper is drawn to the position indicated in FIGS. 1 and 2. 
     The drive sleeve is provided adjacent its extended or flush end with an internal flange 13 having a polygonal bore 14. Inwardly of the internal flange, the drive sleeve is provided with a perforation 15 which receives a key ball 16. The housing sleeve is provided with a pair of diametrically disposed main and minor detent perforations 17 and 18 which are positioned to align radially with the perforation 15. 
     The bore 14 of the internal flange 13 slidably receives a signal shaft 19, the inner end of which is provided with a flange 20, the outwardly facing side of which is conical. The diameter of the signal shaft is such that the key ball 16 is retained in the perforation 20. The signal shaft is provided adjacent the flange 19 with an axial as well as a rachet cam web 21 having a radially inner cam surface 22, and a radially outer cam surface 23, separated by an axially extending stop shoulder 24. The signal shaft 19 is restrained from rotation but is free to move axially. This is accomplished by a plate 25 secured to the cover plate 4 and a portion of the flange 20 which is flattened as indicated by 26. 
     The signal shaft 19 is provided with a socket which receives a spring 27 which engages the cover plate 4 and urges the signal shaft axially outward. 
     Operation of the rotary latch, as shown in FIGS. 1 through 7, is as follows: 
     When the latch is secured, its parts are disposed as shown in FIGS. 1 and 2. The base end of the latch arm 11 has drawn the keeper 7 radially inward. The exposed end of the signal flag 19 is flush with the exposed end of the drive sleeve 9 which is permanently flush with the sleeve 3 and surrounding surface. The axes of the perforations 15, 17 and 18 are coplanar. The key ball 16 bears against the shoulder 24 and cam face 23 as well as the margins of the major detent perforation 17 which is in radial alignment with the key ball. Under these conditions, the latch arm 11 is in its secured or latched engagement with the keeper 7. 
     To open or release the rotary latch a poligonal shaft 28, forming a part of a drive tool, is inserted in the poligonal bore 14, depressing the signal flag 19, as shown in FIGS. 4 and 5, causing the cam web 21 to clear the key ball 16. Upon depressing the signal shaft 19, the drive sleeve 9 may be turned counter clockwise, as viewed in FIG. 1, to withdraw the latch arm 11. Initial rotary movement of the drive sleeve 9 forces the key ball 16 from the detent perforation 17 and into contact with the signal shaft 19. Such initial movement of the drive sleeve 9 causes the key ball 16 to clear the cam web 21 so that, unless restrained by the tool shaft 20, the signal shaft 19 is movable outwardly under force of the spring 27 to a protruding or signal position, as shown in FIG. 1. 
     Protrusion movement of the signal shaft 19 is limited by its conical flanged end 20. The conical surface applies a radially outer force on the key ball 16 so that when the perforation 15 aligns with the detent perforation 18, as occurs when the latch is fully open, the latch is retained in such open position. 
     To re-secure the latch, the shaft 28 depresses the signal shaft 19, then a clockwise turning force is applied causing the latch arm 11 to engage the keeper 7, and also causing the key ball 16 to be forced from the detent perforation 17 whereupon withdrawal of the shaft 28, permits the signal shaft to return to its flush position. 
     Referring to FIGS. 8 and 9 which illustrate a modified signal shaft 29 dimensioned to occupy a depressed signalling position. This is accomplished by providing a longitudinally extending end flange 30 having a locking pocket 31 which receives the key ball 16. When the key ball retainer perforation 15, locking pocket 31 and detent perforation 17 are in registry, the signal shaft 19 is flush and the rotary latch is received in its locked position. 
     Referring to FIGS. 10 through 14, wherein a signal shaft 19a is substituted for the signal shaft 19 and a key cylinder 16a is substituted for the key ball 16. Also essentially square or rectangular slots 15a and 17a are substituted for the circular perforations. Further the signal shaft 19a is provided with a flat flanged end 20a is provided with a radial raised detent 18a which performs the function of the detent perforation 18. A web 21a is substituted for the web 21, which provided with a peripheral cam face 22a above the axial shoulder 24, and a rachet shoulder 23 in place of the cam face 23 in order to accomodate the cylindrical shape of the key 16a. 
     Operation is essentially the same as the embodiment shown in FIG. 1 through 7. With regard to the detent 18a, its surface is rounded so that the engaging end of the key cylinder 16a may be forced over the detent in either direction. The detent 18a may be provided on the conical surfaces of the flanged ends 20 or 30 in place of the detent perforation 18. 
     Having fully described my invention, it is to be understood that I am not to be limited to the details herein set forth, but that my invention is of the full scope of the appended claims.