GB2190423A - Fastener - Google Patents

Abstract

The fastener, specifically for small access panels and doors on exterior surface of aircraft, comprises a receptacle 24 attached to a surround structure (4, Figure 4) and having a lip 27 for seating a cam plate 28 slidably retained within the receptacle 24, but urged into contact with the seating by a spring 29. A stud 23 includes a transverse pin 13 for engaging cam surfaces 18 and recesses 19 of the cam plate 28. A clearance hole 30 in the surround structure will allow insertion of the stud 23 through receptacle 24 such that pin 13 will be located relative to surfaces 18 - quarter turn of stud 23 will draw plate 28 from its seating 27, pin 13 engaging recess 19 to maintain spring loading clearance of e.g. the access panel. As shown receptacle 24 and cam plate 28 are elliptical to prevent rotation - in Figure 6 lugs (31) protruding from the cam plate engage longitudinal slots in walls of receptacle. <IMAGE>

Description

SPECIFICATION Panel fasteners This invention relates to quick release panel fasteners. More particularly, though not exclusively, it relates to quick release panel fasteners for use with small access panels and doors which are located within and are required to conform to the exterior surface of an aircraft.

Small access panels and doors are widely used on aircraft to provide ready access, for numerous reasons, to internal structure, systems and mechanisms, etc. In orderto effect such ready access the panels are frequently located to the aircraft structure by quick release fasteners which must be capable of positive engagement to ensure inflight integrity but ready disengagement when access is required. Furthermore, the panels must preferably lie within apertures such that their outer skin surfaces conform to the aircraft skin profiles.

Certain known panel fasteners achieve this by spring loading means but these known arrangements are such that due to a combination of the spring loading arrangement which they employ and tolerances in the panel installation assembly for example, the head of the fastener may protrude slightly above the skin surface. This is an undesirable feature since, apart from what may be an unsightly appearance, the protrusion may be unacceptable aerodynamically.

It is the object of the present invention to overcome this shortcoming.

According to one aspect of the present invention there is provided a quick release panel fastener comprising a fastener body and a fastener stud portion said body portion including a receptacle, cam plate means and spring means, said receptacle including attachment means, cam plate seating means and spring retaining means, said cam plate means slidably retained within said receptacle and urged into contact with cam plate seating means by said spring means, said cam plate including cam surface means and stud retaining recess means, said fastener stud including a head portion, a shank portion and a protruding pin extending transversely through said shank portion for engaging said cam surface means and said recess means when said stud portion engages said body portion.

Preferably said receptacle, cam plate means and spring means are elliptical such that said cam plate means is restrained against significant rotational movement within said receptacle.

According to a further aspect of the invention there is provided a quick release access panel installation arrangement, said arrangement including a surface panel, an access opening in said panel, an access panel for closing off said access opening and quick release panel fastener means for retaining said access panel in closed position, said panel fastener comprising a fastener body portion located to said surface panel and stud means located to said access panel, said fastener body portion including a receptacle, cam plate seating means and spring retaining means, said cam plate, including cam surface means and stud retaining recess means, being slidably retained within said receptacle and urged into contact with cam plate seating means by said spring means, said stud means including a shank having a protruding pin extending transversely therethrough, the arrangement being such that when the access panel is in closing position with respect to said access opening said stud lies in engagement with said fastener body portion, rotation of said stud causes said pin to move in rising engagement along said cam surface into locking engagement in said stud retaining recess means, the action simultaneously drawing said cam plate from said cam plate seating means against said spring to maintain the access panel in spring loaded locking engagement. One embodiment of the invention will now be described by way of example, with reference to the following drawings in which: Figure lisa plan view on a typical hinged access panel secured by quick release panel fasteners.

Figure 2 is a schematic section through one known arrangement of quick-release panel fastener installation along a line Il-Il in Figure 1.

Figure 3 is a schematic section through one embodiment of a quick-release panel fastener installation in accordance with the present invention.

Figure 4 is a pictorial part sectional arrangement of a known quick-release panel fastener installation.

Figure 5 is a pictorial part sectional arrangement of a quick-release panel fastener installation according to the invention.

Figure 6 is a pictorial arrangement illustrating an alternative anti-rotation device to that described with reference to Figure 4.

Although Figure 2 is indicated as being a section along a line Il-lI in Figure 1, Figures 3, 4, and 5, although not so indicated, are cross-sections through the same fastener position. However, as indicated, Figures 3 and 4 are schematic only.

Figures 4 and 5 are furthermore drawn inverted merely to enable Figure 5 in particular to more clearly disclose this embodiment of the present invention.

Referring to the drawings, Figure 1 illustrates a typical small hinged access panel illustration 1 comprising an access panel 3 lying within an access opening 3a in an aircraft skin panel 33. The panel is secured to the skin panel at one end by means of a piano-type hinge 34 and at the remote end by means of two quick-release panel fastener assemblies 2. The installation includes a surround structure 4 on to which the access panel seats.

Figures 2 and 4 illustrate an arrangement of one known quick release panel fastener, Figure 2 being schematically illustrated in simplified form. Figure 4 illustrates an access panel assembly local to a single quick-release fastener assembly 2 although it will be appreciated that a typical access panel may include a multiplicity of fastenings depending upon design requirements.

The panel installation 1 includes an access panel 3 seated upon a surround structure 4 said surround structure providing the boundary to an access hole in the aircraft skin. The surround structure is inset to a depth 5 substantially equivalent to the overall panel thickness thus ensuring the panel outer surface 5a conforms to that of the aircraft outer profile 6.

In the known arrangement of Figure 4, the fastener assembly comprises a grommet 7 located within the access panel 3 and in which is positioned a retainer 8 seating upon an annular lip 9, the retainer including a flared portion 10 corresponding to the head form 11 of a stud 12 which passes through the retainer as illustrated and includes near to its lower extremity a transverse pin 13 which protrudes to each side of the stud shank 14. The shank diameter is slightly less than the underside of the head form 11 to provide a shoulder 15 for engaging a compression spring 16 positioned as shown and which seats on the lower inside face of the retainer 8.

The fastener assembly further comprises a body portion 17 located concentrically with respect to the stud 12 when the panel is located in position. The body portion 17 includes a cam surface portion 18 for engaging the pin 13 when the stud 12 passes through the said body portion. This cam surface/pin relationship is more clearly illustrated with reference to Figure 5 since that feature is substantially common to both the prior art and present arrangements. The cam surfaces 18 include small recesses 19 substantially semi-circular to conform to the diameter of the pin 13. As the stud is rotated through one quarter of a turn the pin will ride up the face of the cam surface to engage the recesses 19.

Operation of the prior art arrangement is effected by means of a screwdriver engaging the slot 20 in the stud head rotation causing compression of the spring 16 by means of the cam action and spring loading of the door in the closed position maintained by engagement of the pin 13 in the recesses 19.

The shortcoming of this prior art arrangement is that whilst it may be possible in theory to select a nominal stud length to give a flush surface finish, in practice this may be more difficult to achieve because the cam surface 18 and thus the recess 19 forming an integral part of the body portion 17 will be a predetermined height from the undersurface of the surround structure 4. Whilst the spring may ensure positive clamping, material tolerances in the panel assembly may result in slight head protrusion.

That is, the stud is sensitive to the thickness of the surround structure; as indicated in Figure 2 the protrusion ranging from 0--.030 inches. Figure 2 being diagrammatic only, indicates a pan headed stud as distinct from a countersunk head although the protrusion effects are the same.

The arrangement of the present invention overcomes this problem as shown in Figures 3 and 5 which are shown inverted from the arrangement of Figure 4 so that Figure 5 in particular more clearly illustrates the concept. Where relevant, like reference numbers are used. Whilst a grommet 21 is located as shown it is not necessarily an essential feature merely providing a bearing surface for the countersink-head 22 of a stud 23. This stud including a transverse pin 13 for engaging the cam surface 18 and the recesses 19 as appropriate in the arrangement now to be described.

The fastener assembly principally comprises in addition to stud 23 an elliptically cross-sectioned receptacle 24 and a correspondingly elliptical retaining plate 24A sized to form an attachment flange for location to the underside 25 of the surround structure 4. The receptacle incorporates an elliptical opening 26 forming a lip 27 for seating a correspondingly elliptical cam plate 28, whose cam surface portion protrudes through the opening 26.

The cam surface portion includes two diagonally opposed cam surfaces 18 each terminating in pin engaging recesses 19. A compression spring 29 is sandwiched between the cam plate 28 and the retaining plate 24A.

With the panel located in position the clearance hole 30 in the surround structure 4 will allow the insertion of the stud through the receptacle such that the pin 13 will be located in position relative to the cam surface 18. A quarter turn of the stud 23 will cause the pin to ride up the cam surface drawing the cam plate from its seating to compress the spring 29, the pin 13 engaging the recesses 19 to maintain spring loading closure ofthe access panel.

The benefit of this arrangement is clearly illustrated schematically in Figure 3 from which it will be noted that with the pin 13 engaged in the recesses 19 the cam plate 28 will be offset from its seating 27 to give a clearance 30, this 'float' accommodating dimensional tolerances of the assembly whilst maintaining the head 22 flush with the access panel.

The elliptical arrangement as described is intended to prevent rotation of the cam plate within the receptacle. However non-elliptical arrangements can equally apply and one alternative is shown in Figure 6 whereby lugs 31 protruding from the cam plate 28 engage longitudinal slots 32 in the walls of the receptacle 24.

Claims (7)

1. A quick-release panel fastener comprising a fastener body portion and a fastener stud portion said body portion including a receptacle, cam plate means and spring means, said receptacle including attachment means, cam plate seating means and spring retaining means, said cam plate means slidably retained within said receptacle and urged into contact with cam plate seating means by said spring means, said cam plate including cam surface means and stud retaining recess means, said fastener stud including a head portion a shank portion and a protruding pin extending transversely through said shank portion for engaging cam surface means and recess means when said stud portion engages said fastener body portion.

2. Afastener according to Claim 1 in which said receptacle, cam plate means and spring means are of generally elliptical form.

3. A fastener according to Claim 1 in which said receptacle, cam plate means and spring means are of generally circular cross-sectional form the cam plate means being slidably retained within said receptacle for movement in a lengthwise direction but including restraining means to prevent rotation within said receptacle.

4. A fastener according to Claim 3 in which said restraining means comprises at least one projection extending edgewise from said cam plate means and engaging a lengthwise slot in said receptacle wall, said slot extending over the required range of cam plate lengthwise movement.

5; A quick release access panel installation arrangement, said arrangement including a surface panel, an access opening in said panel, an access panel for closing off said access opening and quick release panel fastener means for retaining said access panel in closed position, said panel fastener comprising a fastener body portion located to said surface panel and stud means located to said access panel, said fastener body portion including a receptacle, cam plates means and spring means, said receptacle including cam plate seating means, and spring retaining means, said cam plate, including cam surface means and stud retaining recess means, being slidably retained within said receptacle and urged into contact with cam plate seating means by said spring means, said stud means including a shank having a protruding pin extending transversely therethrough, the arrangement being such that when the access panel is in closing position with respect to said access opening said stud lies in engagement with said fastener body portion, rotation of said stud causes said pin to move in rising engagement along said cam surface means into locking engagement in said stud retaining recess means, the action simultaneously drawing said cam plate from said cam plate seating means against said spring to maintain the access panel in spring loaded locking engagement.

6. A quick release fastener as hereinbefore described with reference to the accompanying drawings.

7. A quick release access panel installation arrangement as hereinbefore described with reference to the accompanying drawings.