Fastener

[0001] 1. Field of the Invention

[0002] This invention relates to a fastener for fastening two planar objects together. In particular, the invention relates to a fastener comprising an anchor and a push pin that is particularly useful for fastening automotive body panels to sheet metal.

[0003] 2. The Prior Art

[0004] Anchor type fasteners having a central pin are known. For example, U.S. Pat. No. 4,571,134 to Seglinger et al. shows a two-piece plastic fastener comprising an anchor and a central pin. The anchor comprises a closed V-shaped insertion portion and a top plate. The anchor is placed through two (or more) planar items to be fastened together. A central pin extends down between the arms of the V and causes the arms to spread when the pin is fully depressed. This spreading anchors the fastener in the rear item and prevents the fastener from coming out. The plate prevents the front item from coming away from the rear item. While this type of fastener is widely used, the closed V-shape of the anchor makes it difficult to install. This is because a large amount of force is required to cause the arms of the V to bend inward sufficiently to pass through an aperture in the item to be mounted, and outward sufficiently enough to let the pin extend to its fully inserted position and retain the anchor in the item. The anchor must bend enough during insertion of the pin so as to prevent the anchor from being inadvertently pulled out by a counter force acting on the items.

[0005] Other fasteners using the same concept are shown in U.S. Pat. Nos. 6,533,515, 6,074,144 and 5,775,860 all to Meyer, as well as U.S. Pat. No. 6,045,309 to LeVey. These fasteners all suffer the same drawback as Beglinger: the closed V formation of the anchor is so resistant to bending that a large amount of force is required to insert the fastener, and bring it into a locked position.

[0006] A plastic fastener having a different configuration is shown in U.S. Pat. No. 4,085,651 to Koscik. In this fastener, the anchor consists of two parallel legs that extend below the plate. Depressing the center pin forces the legs to bend outwards and retain the fastener in the item. This fastener suffers the drawback that the parallel legs are more difficult to insert into a small aperture in the item, as they must often be squeezed together by the operator's fingers in order for the anchor to be inserted.

[0007] In large capacity use, such as automobile assembly lines, it is imperative that the fasteners used to attach body panels to the automobile frame be quick and easy to install in large quantities. Since the fasteners are inserted by hand, they should not require undue force to complete the insertion, due to operator fatigue. They should also be able to be installed using a minimum number of steps.

[0008] It is therefore an object of the invention to provide a fastener that is simple to install with a low amount of force.

[0009] It is another object of the invention to provide a fastener that is strong and reliable.

[0010] It is another object of the invention to provide a fastener that does not require assembly prior to use.

[0011] It is yet another object of the invention to provide a fastener that is simple and inexpensive to manufacture.

[0012] These and other objects are accomplished by a fastener comprising an anchor and a central pin. The anchor comprises a top plate to which a central leg is connected. The central leg extends perpendicularly down from the top plate. At the free end of the central leg are two anchor arms that extend up and outward from the free end, forming an arrowhead shape. Each anchor arm has a free end facing upward. The anchor arms are flexible and can flex inward as the anchor is placed through a hole in an item to be fastened.

[0013] Connected to the top surface of the top plate is a push pin assembly. The push pin assembly is integrally molded with the top surface of the top plate via small connection areas. This way, only a single mold is required for molding the fastener. Depressing the push pin breaks the connection areas to create a two-piece anchor from the single part. The push pin comprises a push button and a pin connected to the underside of the push button. The pin consists of a vertical post having a channel therein for accommodating the central leg of the anchor. Pushing the push button downward causes the pin to slide along the central leg until the end of the pin abuts the inner surface of the anchor legs. This causes the anchor arms to be pushed outward and to anchor the fastener into the items to be fastened.

[0014] Extending down from the top plate on either side of the central leg are two retaining arms. Each retaining arm has a structure that interacts with a corresponding structure on the anchor legs as they are forced outward to prevent the anchor arms from extending beyond a predetermined limit. This prevents the anchor arms from being bent entirely back by a sudden force and breaking. The interacting structures could be interacting hooks, protrusions or any other structure that would prevent the anchor arms from moving beyond the retaining arms. The outside surfaces of the retaining arms are suited to center the fastener within the hole of the panel.

[0015] Preferably, there are guide flanges located on an inner surface of the anchor arms, that guide the pin and keep it aligned with the central leg as it slides down toward the bottom of the anchor. The flanges extend out around one side of the anchor, on the opposite face of the pin from the channel, to prevent the pin from moving laterally beyond a predetermined limit. The pin has a notch cut into its lower end. When the bottom of the pin contacts the guide flange, the flange snaps into the notch and prevents upward movement of the pin. An additional notch and flange arrangement is located higher up on the pin and anchor assembly and also snaps closed to provide further insurance against upward movement of the pin after the fastener is in its fully locked position.

[0016] Preferably, the fastener can be set to a pre-loaded state prior to insertion into the items to be fastened. When the fastener is first molded, the pin is integrally formed with the anchor and extends up though an aperture in the top plate. The aperture is preferably U-shaped to accommodate the channel-containing pin structure. Pressing the push button down slightly causes the connections to the anchor to break and causes the pin to slide through the aperture into a partially inserted position. In this pre-loaded state, the fastener can be easily inserted into the items to be fastened, and then only a small pressing motion on the push pin can move the fastener into a fully locked position. Prior to achieving the fully locked position, the pin can freely move up and down within the anchor. There are preferably grooves on the pin that lock into protrusions located underneath the top plate after the pin has been fully inserted in the top plate, to prevent the pin from sliding back up out of the apertures after full insertion into the anchor.

[0017] The open V-shape of the anchor arms gives them extra flexibility so that insertion of the pin into apertures in the items to be fastened is simple and does not require a lot of force. Similarly, pressing the push pin into the anchor legs does not require a lot of force for the legs to extend outward and lock the fastener to the items to be fastened.

[0018] Because the fastener is molded with the pin and anchor already together, it does not require any assembly to use. Traditional two-piece anchor systems require assembling of the pin and anchor prior to use, requiring additional time and causing additional operator fatigue. In the present invention, all that is required to use the anchor is depressing the pin enough to break the connections and pre-load the fastener. This can be done on the manufacturing end or on the assembly line.

[0029] Referring now in detail to the drawings, FIGS. 1-6 show the fastener 10 according to the invention as it goes from an initially molded state (FIG. 1) into a fully locked position (FIG. 6) FIGS. 1 and 2 show the fastener 10 according to the invention in an initial molded state. Fastener 10 comprises an anchor 20 and a push pin assembly 30. Anchor 20 has a top plate 21 connected to a central leg 23. Central leg 23 extends substantially perpendicular to the bottom surface of top plate 21. There are two flexible anchor arms 24 connected to the free end of central leg 23. Each anchor arm 24 extends up and away from central leg 23, and each anchor arm 24 has a free end 25 that is not connected to anything. Anchor arm 24 has a tapered top portion 28 that widens as arm 24 extends from its free end 25 back toward the tip of central leg 23, creating a slanted wall facing central leg 23.

[0030] Push pin assembly 30 comprises a push button 31 and a pin 32 connected to and extending downward from the bottom surface of push button 31. Pin 32 is adapted to fit through an aperture 22 in top plate 21, such that pushing push button 31 causes pin 32 to extend through the aperture 22 and slide along the slanted wall of anchor arm 24 as push button 31 is depressed to force anchor arms 24 to bend away from central leg 23 and away from each other. (See FIGS. 4-6).

[0031] As shown in FIG. 1, and in greater detail in FIG. 8, pin portion 32 has a channel 33 cut therein. Channel 33 corresponds in shape to central leg 23 of anchor 20, so that depressing push button 31 causes pin 32 to slide along central leg 23 with the central leg 23 fitting at least partially within channel 33 (See FIG. 8). This way, central leg 23, in addition to supporting anchor arms 24, acts as a guide for pin 32. Channel 33 is not shown in FIGS. 2-6, as it is facing away in those views.

[0032] There are two retaining arms 40 extending down from the bottom surface of top plate 21 As shown in FIGS. 5 and 6, retaining arms 40 contact the free end 25 of anchor arms 24 when push button 31 is fully depressed and prevent anchor arms 24 from extending out beyond a predetermined limit.

[0033] As shown in FIGS. 1-4, there is a latching mechanism comprising a hook 42 on free end 25 of retaining arms 40, as well as a corresponding hook 43 (shown in FIG. 1) on the free ends 25 of anchor arms 24. Hooks 42 and 43 engage each other when push button 31 is fully depressed to prevent anchor arms 24 from escaping beyond retaining arms 40. There is a flange 41 located on an edge of retaining arms 40 (shown in detail in FIG. 7), which prevents any lateral movement of the anchor arms 24 when arms 24 are in the fully extended position push button.

[0034] As shown in FIG. 1, there is a transversely extending guide flange 26 on an inside surface of anchor arms 24. Guide flange 26 guides pin 32 as it extends down toward anchor arms 24 and keeping pin 32 oriented parallel to central leg 23. Preferably, one end of guide flange 24 extends outwardly and around toward central leg 23 and prevents lateral pivoting of pin 32, to prevent central leg 23 from coming out of channel 33 when push button 31 is depressed.

[0035] FIGS. 1 and 2 show fastener 10 in its initially molded state. Push pin assembly 30 is integrally molded with anchor 20 via connection points 36 connecting top plate 21 with a bottom section of pin 32. As shown in FIG. 3, downward pressure on push button 31 causes connection points 36 to break and pin 32 to extend through aperture 22 in top plate 21. This action can be easily done at either the manufacturing level or at the installation site, prior to installation of fastener 10.

[0036] FIGS. 4-6 show the installation of fastener 10 on two flat items 50 and 60. Typically, items 50 and 60 would be an automobile body panel and sheet metal, respectively, but any substantially flat item could be fastened with fastener 10. As push button 31 is depressed and anchor arms are forced outwardly, this outward extension of anchor arms 24 retains anchor 20 securely within items 50 and 60 (see FIGS. 5 and 6).

[0037] There is a locking mechanism to lock fastener 10 in a locked position on items 50 and 60, which comprises notches 35 in pin 32. The bottom of guide flange 26 on anchor arms 24 catch notches 35 to prevent upward movement of pin 32 once push button 31 is fully depressed. There is a further set of notches 34 in pin 32, and a pair of flanges 48 extending underneath the bottom surface of top plate 21. Depressing push button 31 completely causes flanges 48 to snap into notches 35 and further prevent upward movement of push pin assembly 30.

[0038] It should be noted that enough vertical clearance must be allowed between hook 43 on arm 24 and flange 48, so that pressing legs 24 together to force them through a hole in a panel causes the vertical extension of legs 24 to increase, and their width to narrow. Flange 48 is positioned so as not to interfere with this movement of legs 24 as fastener 10 is inserted into an item to be fastened. In addition, hook 43 is fashioned so that while it prevents further horizontal extension of arms 24, it does not prevent arms 24 from being further compressed, if necessary. For example, as fastener 10 is placed into a pre-locked position shown in FIG. 5, hook 43 engages hook 24, but releasing push button 31 prior to final locking may still allow legs 24 to be compressed and disengaged from hook 43.

[0039] The fastener according to the present invention requires no assembly, is simple to install, does not cause extensive operator fatigue and allows for reliable fastening of two or more planar items together.

[0040] Accordingly, while only a single embodiment of the present invention has been shown and described, it is obvious that many changes and modifications may be made there unto without departing from the spirit and scope of the invention.