TECHNICAL FIELD

[0001] The present invention relates to high security fasteners of the type used to secure a member such as a vehicle wheel rim to an associated stud, and more particularly to a high security fastener having a spring shroud.

BACKGROUND ART

[0002] Locking wheel nuts and wheel bolts are commonly used to attach wheels to axel hub assemblies of automobiles and other vehicles. These fasteners are designed with security features that are intended to thwart theft by rendering the fasteners difficult to remove with conventional tools. In particular, the fasteners do not have the usual hexagonal head pattern found on conventional nuts and bolts and instead have smooth cylindrical sidewalls that cannot be gripped by standard wrenches. Fastener removal requires the use of a special security tool having a unique key pattern that matches a corresponding groove pattern formed in the fastener end face.

[0003] Additional security can be obtained by fitting a free-spinning shroud or cap over the security fasteners cylindrical sidewalls, such that the shroud is in concentric relationship therewith. The shroud discourages the use of theft devices that could otherwise be used to grip the sidewalls and remove the fastener without an authorized security tool. Because the shroud substantially surrounds all exposed surfaces of the sidewalls, no rotational purchase can be obtained in the fastener. The theft device can only engage the shroud, which freely spins under action of the theft device while the main body of the fastener remains stationary.

BRIEF SUMMARY

[0004] With parenthetical reference to corresponding parts, portions or surfaces of the disclosed embodiment, merely for the purposes of illustration and not by way of limitation, an improved security fastener assembly (15) configured to engage a corresponding threaded element (16) orientated about a central axis (x-x) and to bear against a member (18) to be secured to the threaded element is provided comprising: a fastener lock (23) orientated about the central axis; the fastener lock having a tool-engaging portion (25) to which a driving torque may be applied, a threaded fastening portion (37) configured to mate with the threaded element, and a shroud retainer portion (24) orientated about the central axis; a helical coil (20) orientated about the central axis; the helical coil having a first coil end (61), a second coil end (62), and a central coil portion therebetween; the shroud retainer portion of the fastener lock configured to directly or indirectly restrain the helical coil from movement along the central axis in an axial direction that is away from the member to be secured to the threaded element; and the helical coil configured to be supported in rotatable relationship with the fastener lock such that the helical coil will rotate relative to the fastener lock under an applied external torque prior to the fastener lock rotating when the fastener lock is engaged with the threaded element at a design installation torque.

[0005] The security fastener assembly may comprise a nut (19) configured to mate with the threaded element and having a first nut end (52), a second nut end (50), an external nut surface (53, 54, 55), and an internal threaded nut surface (51) orientated about the central axis and extending substantially through an entire axial length of the nut from the first nut end to the second nut end.

[0006] The security fastener assembly may comprise an intermediate retainer washer (22) orientated about the central axis and having a first washer end (42), a second washer end (40), an external washer surface (41), and an internal washer surface (43), the intermediate retainer washer configured to be disposed axially between the second coil end (62) of the helical coil and the shroud retainer portion (33) of the fastener lock, the intermediate retainer washer configured to be supported in rotatable relationship with the fastener lock such that the intermediate retainer washer will rotate relative to the fastener lock under the applied external torque prior to the fastener lock rotating when the fastener lock is engaged with the threaded element at the design installation torque. The shroud retainer portion of the fastener lock may comprise an outwardly extending annular shoulder (24) radially overlapping the intermediate retainer washer. The outwardly extending annular shoulder (24) of the shroud retainer portion of the fastener lock may comprise an outer circumference having an outer shoulder radius (R9) from the central axis; the internal washer surface (43) of the intermediate retainer washer may comprise an inner circumference having an inner washer radius (R6) from the central axis; the external washer surface (41) of the intermediate retainer washer may comprise an outer circumference having an outer washer radius (R8) from the central axis; the second coil end (62) of the helical coil may comprise an inner circumference having a second inner coil radius (R4) from the central axis; the second inner coil radius (R4) may be greater than the outer shoulder radius (R9); the inner washer radius (R6) may be less than the outer shoulder radius (R9); and the outer washer radius (R8) may be greater than the inner coil radius (R4). [0007] The first nut end (52) of the nut may comprise an outer circumference having a first nut outer radius (R3) from the central axis; the first coil end (61) of the helical coil may comprise an inner circumference having a first inner coil radius (R4) from the central axis; and the first inner coil radius (R4) may be greater than the first nut outer radius (R3). The first inner coil radius may be the same as the second inner coil radius.

[0008] The threaded fastening portion of the fastener lock may comprise an internal threaded fastener surface orientated about the central axis and extending substantially through an entire axial length of the fastener lock from a first fastener end to a second fastener end. The helical coil may be configured to be supported concentrically with the nut about the central axis. The helical coil may comprise an internal coil surface between the first coil end and the second coil end, and the internal coil surface of the coil may face the external nut surface of the nut. The first nut end (52) of the nut may be configured to face the member (18) to be secured to the threaded element, the first coil end (61) of the helical coil may be configured to face the member (18) to be secured to the threaded element, the second coil end (62) of the helical coil may be configured to face the first washer end (42) of the intermediate retainer washer, and the helical coil may be configured to be in compression between the member (18) to be secured to the threaded element and the first washer end (42) of the intermediate retainer washer.

[0009] The security fastener assembly may comprise an intermediate spacer ring (21) orientated about the central axis and having a first spacer end (47), a second spacer end (45), an external spacer surface (48), and an internal spacer surface (46), the intermediate spacer ring configured to be disposed axially between the second nut end (50) of the nut and the first washer end (42) of the intermediate retainer washer, and the intermediate spacer ring configured to be disposed radially between an external fastener surface (34) of the fastener lock and an internal coil surface (63) of the helical coil. The intermediate spacer ring may be configured to be supported in rotatable relationship with the fastener lock such that the intermediate spacer ring will rotate relative to the fastener lock under the applied external torque prior to the fastener lock rotating when the fastener lock is engaged with the threaded element at the design installation torque.

[0010] The threaded element may comprise a threaded stud, the member to be secured to the threaded element may comprise a wheel rim, and the fastener lock may comprise a lock nut. The tool-engaging portion of the fastener lock may comprise a tapered outer surface (31) and a plurality of circumferentially spaced longitudinally extending key-receiving grooves (25) in the tapered outer surface arranged in a lock pattern to which a driving torque may be applied. The external nut surface of the nut may comprise a hexagonal portion (56) to which a driving torque may be applied.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIG. 1 is a perspective view of a first embodiment of an improved security fastener assembly securing a wheel rim to a threaded stud.

[0012] FIG. 2 is a longitudinal vertical sectional view the security fastener assembly shown in FIG. 1.

[0013] FIG. 3 is an exploded view of the security fastener assembly shown in FIG. 1.

[0014] FIG. 4 is an exploded sectional view of the security fastener assembly shown in FIG. 2.

[0015] FIG. 5 is an enlarged perspective view of the fastener lock and shroud assembly shown in FIG. 1.

[0016] FIG. 6 is a side elevational view of the fastener lock and shroud assembly shown in FIG. 5.

[0017] FIG. 7 is a right elevational view of the fastener lock and shroud assembly shown in FIG. 6.

[0018] FIG. 8 is an enlarged sectional view of the fastener lock and shroud assembly shown in FIG. 2.

[0019] FIG. 9 is an enlarged sectional view of the fastener lock shown in FIG. 8.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] At the outset, it should be clearly understood that like reference numerals are intended to identify the same structural elements, portions or surfaces consistently throughout the several drawing figures, as such elements, portions or surfaces may be further described or explained by the entire written specification, of which this detailed description is an integral part. Unless otherwise indicated, the drawings are intended to be read (e.g., crosshatching, arrangement of parts, proportion, degree, etc.) together with the specification, and are to be considered a portion of the entire written description of this invention. As used in the following description, the terms“horizontal”, “vertical”,“left”,“right”,“up” and “down”, as well as adjectival and adverbial derivatives thereof (e.g., “horizontally”, “rightwardly”,“upwardly”, etc.), simply refer to the orientation of the illustrated structure as the particular drawing figure faces the reader. Similarly, the terms “inwardly” and “outwardly” generally refer to the orientation of a surface relative to its axis of elongation, or axis of rotation, as appropriate.

[0021] Referring now to FIGS. 1-9, an improved multiple piece safety fastener is provided, a first embodiment of which is generally indicated at 15. Fastener 15 generally includes fastener lock 23, helical coil helical coil shroud 20, which rotates about axis x-x relative to fastener lock 23, intermediate retainer washer 22, which is rotatable about axis x-x relative to both fastener lock 23 and helical coil shroud 20, and spacer ring 21, which is rotatable about axis x-x relative to both fastener lock 23, helical coil shroud 20 and intermediate retainer washer 22.

[0022] With reference to FIG. 9, fastener lock 23 is a specially configured ring-like member elongated along axis x-x and is generally bounded by rightwardly-facing vertical annular surface 30, rightwardly and outwardly-facing frusto-conical surface 31, outwardly- facing horizontal cylindrical surface 32, leftwardly-facing annular vertical surface 33, outwardly-facing horizontal cylindrical surface 34, leftwardly-facing annular vertical surface

35, leftwardly and inwardly-facing frusto-conical surface 26, inwardly-facing horizontal threaded cylindrical surface 37, rightwardly and inwardly-facing frusto-conical surface 38, and inwardly-facing horizontal cylindrical surface 39, joined at its right edge to the inner edge of surface 30.

[0023] As shown, fastener lock 23 includes inner through-bore 26, defined by surfaces

36, 37, 38 and 39, extending from left end face 35 of fastener lock 23 to right end face 30 of fastener lock 23, and thus extending the entire axial length of fastener lock 23. Threaded surface 37 defines an internally threaded fastening portion of fastener lock 23 having radius R1 from axis x-x, which corresponds to the outer radius of threaded surface 58 of stud 16. While in this embodiment only surface 37 of bore 26 is internally threaded, through-bore 26 may be alternatively configured to be internally threaded over an alternative portion or over all of its length. As a further alternative, fastener lock 23 could have a closed right end such that bore 26 extends only partially through fastener lock 23.

[0024] Surface 31 and grooves 25 therein generally define an outer tool engaging portion of fastener lock 23. In this embodiment, surface 31 is tapered or sloped from outer surface 32 to the right and inwards towards longitudinal axis x-x at a tapered angle. Frusto-conical surface 31 provides an outer tapered surface that serves as a security feature in that it is difficult to grip using an unauthorized tool. Should an attempt be made to rotate fastener lock 23 by griping on surface 31 using an unauthorized tool, such tool will tend to slide on tapered surface 31 and it will tend to be difficult to find an attack point on fastener lock 23. [0025] The right side of lock fastener 23 has a specially configured external profile to which a drive torque may be applied. In this embodiment, this profile comprises a key receiving pattern that may be implemented as a set of circumferentially spaced externally facing longitudinally extending key-receiving grooves 25 in tapered surface 31 arranged in a lock pattern to which a drive torque may be applied. Lock pattern configurations that use formations of other than grooves could potentially also be used. Each lock pattern groove 25 is formed by a generally arcuate surface extending radially inwards towards longitudinal axis x-x from tapered surface 31. This arcuate surface thereby intersects and forms an edge at its respective junction with tapered surface 31. In order to impart lock pattern uniqueness, lock pattern grooves 25 may be patterned in any suitable manner, such as by employing a selected number of grooves and/or by varying other features thereof, such as the spacing between grooves and/or the width, length, depth, profile or other configuration or feature thereof. Such grooves are configured so that a corresponding drive key tool (no shown) may be used to engage lock pattern grooves 25.

[0026] The key tool includes a socket and a drive portion. The entrance to the socket is formed with a key pattern that may be implemented as a set of circumferentially arranged key pattern lobes. The key pattern lobes are configured and arranged to engage lock pattern grooves 25 when the socket is placed over the right end of fastener lock 23. Behind the key pattern lobes, the socket is substantially cylindrical and sized to accommodate the right end of fastener lock 23. The drive portion of the key may be formed with a conventional hex (or other) configuration for engagement by a standard wrench or drive tool. Thus, a key having a matching set of key pattern lobes may be used to engage lock pattern grooves 25 to actuate fastener lock 23 about axis x-x. Other tools either will not fit or will not be able to properly engage and rotate fastener lock 23 when it is installed at its intended design installation torque on threaded stud 16.

[0027] Surfaces 34, 33 and 32 generally define outwardly extending annular shoulder 24 of fastener lock 23. Surface 34 of fastener lock 23 has radius R7 from axis x-x that is slightly less than inner radius R6 of both spacer ring 21 and retainer washer 22. Surface 32 of fastener lock 23 has radius R9 from axis x-x that is greater than inner radius R6 of both spacer ring 21 and retainer washer 22. Spacer ring 21 and retainer washer 22 are each rotationally and concentrically supported on cylindrical surface 34 of fastener lock 23 adjacent shoulder 24. Radially overlapping annular surface 33 of shoulder 24 of fastener lock 23 retains spacer ring 21 and retainer washer 22 from moving axially along axis x-x in a direction away from rim 18 when fastener lock 23 is threaded onto stud 16. Spacer 21 and retainer washer 22 are sized to spin about axis x-x on surface 34 relative to fastener lock 23.

[0028] With reference to FIG. 4, retainer washer 22 is a specially configured ring-like member elongated along axis x-x and is generally bounded by rightwardly-facing vertical annular surface 40, outwardly-facing horizontal cylindrical surface 41, leftwardly-facing annular vertical surface 42, and inwardly-facing horizontal cylindrical surface 43, joined at its right edge to the inner edge of surface 40. Inner facing surface 43 of washer 22 has inner radius R6 from axis x-x, and outer facing surface 41 of retainer washer 22 has outer radius R8 from axis x-x. Retainer washer 22 is sized to spin about axis x-x on surface 34 relative to fastener lock 23.

[0029] With reference to FIG. 4, spacer ring 21 is a specially configured ring-like member elongated along axis x-x and is generally bounded by rightwardly-facing vertical annular surface 45, outwardly-facing horizontal cylindrical surface 48, leftwardly-facing annular vertical surface 47, and inwardly-facing horizontal cylindrical surface 46, joined at its right edge to the inner edge of surface 45. Inner facing surface 46 of spacer 21 has inner radius R6 from axis x-x, and outer facing surface 48 of spacer 21 has outer radius R2 from axis x-x. Spacer 21 is sized to spin about axis x-x on surface 34 relative to fastener lock 23.

[0030] With reference to FIG. 4, nut 19 is a specially configured ring-like member elongated along axis x-x and is generally bounded by rightwardly-facing vertical annular surface 50, inwardly-facing horizontal threaded cylindrical surface 51, leftwardly-facing annular vertical surface 52, outwardly-facing horizontal cylindrical surface 53, rightwardly and outwardly-facing frusto-conical surface 54, rightwardly-facing vertical annular surface 55, and outwardly -facing horizontal hexagonal surface 56, joined at its right edge to the outer edge of surface 50.

[0031] As shown, nut 19 includes inner through-bore 28, defined by threaded surface 51 extending from left end face 52 of nut 19 to right end face 50 of nut 19, and thus extending the entire axial length of nut 19. Inner through-bore 28 has radius R1 from axis x-x, which corresponds to the outer radius of threaded surface 58 of stud 16. Nut 19 also includes a skirt portion defined by surfaces 53, 54 and 55, with nut 19 having maximum radius R3 from axis x-x to surface 53 at end 52. External surface 56 is a conventional hexagonal head profile found on conventional nuts and bolts and generally defines an outer tool engaging portion of nut 19 for engagement by a standard wrench or drive tool such that nut 19 may be threaded onto stud 16 and driven about axis x-x to tighten or loosen nut 19 against rim 18 on stud 16 with a standard wrench or hexagonal socket. [0032] With reference to FIGS. 4, 6 and 8, shroud 20 is a specially configured ring-like member elongated along axis x-x and is generally formed of solid metal wire bent into a spiraling coiled shape having multiple coiled turns 60 to form a helical coiled spring. In this embodiment, helical coil 20 has a wire diameter of between about 2.5 mm and about 3.5 mm, a pitch of between about 8 mm and 10 about mm, and a compressed length of between about 28 mm to 35 mm. Coiled shroud 20 has inner coil radius R4 from axis x-x and outer coil radius R5 from axis x-x and extends axially along axis x-x from left coil end 61 to right coil end 62.

[0033] As shown in FIGS. 2 and 8, surface 48 of spacer 21 has outer radius R2 slightly less than inner radius R4 of coiled shroud 20. In this embodiment, radius R2 is the same as radius R2 of nut 19. Spacer 21 is disposed radially between inner surface 63 of coil shroud 20 adjacent end 62 and surface 34 of fastener lock 23. Spacer 21 thereby maintains the concentric alignment of coil shroud 20 about axis x-x at end 62. Coiled shroud 20 is sized to spin about axis x-x on surface 48 of spacer 21 relative to fastener lock 23. Similarly, surface 53 of nut 19 has outer radius R3 slightly less than inner radius R4 of coiled shroud 20. Nut 19 thereby maintains the concentric alignment of coil shroud 20 about axis x-x at end 61. Coiled shroud 20 is sized to spin about axis x-x on surface 53 of nut 19 relative to fastener lock 23.

[0034] In FIGS. 1-4, the improved fastener assembly 15 is shown in conjunction with automotive wheel rim 18 on which a tire is mounted. Rim 18 is attached to the axle by means of a plurality of nuts 19 and fastener locks 23, all of which are threaded onto associated threaded studs 16. Rim 18 is positioned on each threaded stud 16 with end 59 of stud 16 extending through opening 17 in rim 18. Fastener lock 23 and nut 19 are sized and installed such that the interior threads of inner bores 28 and 26, respectively, engage the corresponding exterior threads of surface 58 of stud 16.

[0035] Nut 19 is threaded on the portion of stud 16 extending from end face 65 of rim 18. Nut 19 is tightened against end face 65 of rim 18 such that leftwardly-facing annular end face 52 of nut 19 abuts against rightwardly-facing annular end face 65 of rim 18 to hold rim 18 on stud 16. Helical coil shroud 20 is the positioned to extend over and around nut 19 such that leftwardly-facing end 61 of coiled shroud 20 abuts against rightwardly-facing annular end face 65 of rim 18. Washer 22 is positioned on and around surface 34 of fastener lock 23 such that rightwardly-facing end 40 of washer 22 abuts against leftwardly-facing annular shoulder 33 of fastener lock 23. Spacer 21 is positioned on and around surface 34 of fastener lock 23 such that rightwardly-facing end 45 of spacer 21 abuts against leftwardly-facing annular end face 42 of washer 22. Fastener lock 23 is then threaded on the portion of stud 16 extending from end face 50 of nut 19, with spacer 21 position interior to end 62 of coiled shroud 20, such that that portion of leftwardly-facing annular surface 42 that extends radially beyond surface 48 of spacer 21 of washer 22 abuts against rightwardly-facing end 62 of coiled shroud 20. Thus, the exterior right end portion of stud 16 is threaded and fastener lock 23 is sized and installed such that the interior threads of inner bore 26 engage the exterior threads of end portion of stud 16. In this installation, fastener lock 23 is arranged so that end 59 of stud 16 is not exposed outside bore 26 and end face 30 of fastener lock 23 when fastener lock 23 is rotationally installed on wheel stud 16. To provide appropriate axial spacing, coiled spring shroud 20 may be compressed or expanded to provide appropriate axial length and to cover nut 19 so as to restrict access to nut 19 on stud 16. By using a helical coil as the shroud, the axial length of shroud 20 is variable. Fastener lock 23 can only be turned by a proper mating key, and thus fastener lock 23 together with shroud 20 restrict unauthorized access to nut 19 and removal of rim 18 from stud 16.

[0036] The ability of helical coil shroud 20 and retainer washer 22 to spin relative to fastener lock 23 and nut 19 provides a security feature that protects shroud 20 or washer 22 from being used as a purchase point for unauthorized tools. Should an attempt be made to rotate fastener assembly 15 by gripping an exposed part, shroud 20 and retainer washer 22 will tend to spin without any rotation being imparted to fastener lock 23 or nut 19.

[0037] As shown, coiled shroud 20 may be compressed axially between rightwardly- facing surface 65 of rim 18 and leftwardly-facing annular surface 33 of shoulder 24 of fastener lock 23, with the amount of compression in coil 20 controlled by rotation of fastener lock 23 about axis x-x on shaft 59 of stud 16. Thus, when installed, shoulder 24 of fastener lock 23, defined by annular surface 33 and having outer radius R9, radially overlaps retainer washer 22 having inner radius R6. Retainer washer 22 having outer radius R8 radially overlaps coiled end 62 of helical coil shroud 20 having inner radius R4, thereby retaining helical coil shroud 20 from moving axially to the right relative to surface 65 of rim 18. So helical coil shroud 20 is free to rotate about center axis x-x relative to rim 18, nut 19 and fastener 23, but is restrained from moving axially to the right off nut 19 and stud 16. In the other direction, surface 65 of rim 18 retains helical coil shroud 20 such that helical coil shroud 20 is free to rotate about center axis x-x but is restrained from moving axially to the left. Accordingly, coiled shroud 20 is axially bounded at one end by shoulder 24, defined by annular surface 33, and axially bounded at the other end by rim 18. Helical coil shroud 20 is thereby both mounted concentrically on stud 16 such that it does not move axially off surface 53 of nut 19 but is substantially free to rotate about axis x-x relative to nut 19 and fastener lock 23.

[0038] While in this embodiment shoulder 24 prevents axial movement of helical coil shroud 20 indirectly via the expanded radius of retainer washer 22, such axial restraint may be provided directly as an alternative by changing the radial dimensions of the fastener key. Also, the shape and profile of washer 22 may be varied.

[0039] The components of the embodiments of the fastener assembly may be formed of various different materials. For example, and without limitation, steel, stainless steel, brass, aluminum and titanium may be used. As another alternative, and without limitation, non- metallic materials may be used in some applications.

[0040] The present invention contemplates that many changes and modifications may be made. Therefore, while forms of the improved fastener assembly have been shown and described, and a number of alternatives discussed, persons skilled in this art will readily appreciate that various additional changes and modifications may be made without departing from the scope of the invention, as defined and differentiated by the following claims.