TOOTHED FASTENER SYSTEM

Abstract: A system (10) of toothed fasteners (12) for fastening an object, such as a motor vehicle wheel, comprises a plurality of fasteners (12) each having a threaded portion and a head portion (16) provided integral to the threaded portion. The head portion (16) of each fastener (12) is provided with an associated toothed wheel (18) having a toothed outer periphery (20). The teeth of the toothed outer periphery (20) of each toothed wheel (18) are adapted to function like the teeth of a conventional gearwheel whereby, in use, the toothed outer periphery (20) can be engaged laterally for transmitting a torque to the associated fastener (12) of the toothed wheel (18). Each fastener (12) is provided with friction reducing means comprising a solid dry lubricant material contained with in a region between the head portion (16) of the fastener (12) and the object to be fastened whereby, in use, the solid dry lubricant material can act as a low friction bearing for the fastener (12). The fasteners (12) are arranged so that the toothed outer peripheries (20) of the associated toothed wheels (18) of at least two of the fasteners (12) can be simultaneously mechanically coupled to a gear rotating mechanism (22) whereby, in use, the at least two fasteners (12) can be tightened or loosened simultaneously by operating the gear rotating mechanism (22). A motor vehicle wheel incorporating the toothed fastener system (10) is also dscribed.

Description: TOOTHED FASTENER SYSTEM FIELD OF THE INVENTION The present invention relates to a system of toothed fasteners in which two or more of the fasteners can be tightened or loosened simultaneously using a gear rotation mechanism tool, and relates particularly, though not exclusively, to such a system incorporated in a motor vehicle wheel. BACKGROUND TO THE INVENTION Motor vehicle wheels are conventionally secured to a vehicle by a plurality of threaded wheel bolts received in threaded apertures, or wheel nuts received on threaded studs, provided in the wheel flange on the vehicle axle. A conventional wheel nut or bolt comprises a hexagon shaped head portion designed to be gripped by a wheel brace or spanner, which when tightened against the face of the wheel surrounding the fastener hole encounters a high degree of friction. As the underside of the head portion contacts the face of the wheel and the stud or bolt is tensioned to the required pre-load, a significant proportion of the torque required to turn the fastener is lost to friction. It is estimated that up to 60% of the torque used to tighten a typical motor car wheel nut is required to overcome friction. Furthermore, frequently the wheel fasteners are exposed to the elements and the contacting surfaces of the fasteners and the wheel are subject to corrosion, particularly where galling has occurred. These factors combine to make it extremely difficult to loosen the wheel fasteners, so that if the wheel must be removed, for example to change a tyre, a motorist alone may be unable to undo the wheel fasteners in order to remove the wheel. Conventionally, changing a wheel involves individually loosening and removing each of the wheel fasteners from the wheel, so that the wheel can be lifted off the wheel flange on the vehicle axle. The replacement wheel is fitted by being brought up to, and correctly aligned on, the wheel flange and each of the fasteners must then be relocated one by one and started on the thread, before being screwed down against the wheel. Apart from the problems connected with removing the fasteners in the first place, as noted above, difficulty is also often encountered in correctly locating the wheel nuts or bolts and holding the wheel while starting the wheel nut or bolt on the thread. A further problem with conventional wheel fasteners is that they are frequently incorrectly tightened due to the difficulty in judging or applying the necessary torque. For the motorist on the road the tension of the fastener can generally only be determined by feel and guess-work, sometimes resulting in the fastener being too loose or overtight. When a fastener is too loose, the wheel may work off the axle due to the cyclic loading and vibration the fastener is subject to during vehicle motion, whilst overtightening sometimes breaks the fastener or damages the thread by over-crossing (thread crossing makes the fastener unremovable by conventional tools) . SUMMARY OF THE INVENTION The present invention was developed with a view to providing a toothed fastener system which is capable of overcoming one or more of the above-noted problems common to conventional threaded f steners . Although the invention will be described with particular reference to motor vehicle wheel fasteners, it will be understood that the fastener system can be used in any application where one or more of the above-noted problems may occur. According to one aspect of the present invention there is provided a system of toothed fasteners for fastening an object, the system comprising: a plurality of fasteners each having a threaded portion and a head portion provided integral to the threaded portion, said head portion of each fastener having associated with it a toothed wheel having a toothed outer periphery, wherein the teeth of the toothed outer periphery are adapted to function like the teeth of a conventional gearwheel whereby, in use, the toothed outer periphery of each toothed wheel can be engaged laterally for transmitting a torque to its associated fastener; each fastener being provided with friction reducing means comprising a solid dry lubricant material contained within a region between the head portion of the fastener and the object whereby, in use, the solid dry lubricant material can act as a low-friction bearing for the fastener; and wherein said fasteners are arranged so that the toothed outer peripheries of the associated toothed wheels of at least two of the fasteners can be simultaneously mechanically coupled to a gear rotating mechanism whereby, in use, said at least two fasteners can be turned in a tightening or loosening direction simultaneously by operating the gear rotating mechanism. Preferably the diameter of said associated toothed wheel is between one to ten times the diameter of a head portion of a conventional fastener. In a preferred embodiment the head portion of each fastener is axially movable relative to the associated toothed wheel, there being provided engaging means for normally preventing the toothed wheel from rotating relative to the head portion. In an alternative embodiment said toothed wheel is provided integral to the head portion of the fastener, or may be formed by the head portion itself suitably modified. Advantageously said plurality of fasteners are all arranged with their axes of rotation on the circumference of a common circle whereby, in use, said gear rotating mechanism can be simultaneously mechanically coupled to the toothed outer peripheries of the toothed wheels of said at least two fasteners by rotating on an axis passing through the centre point of said circle to tighten or loosen said at least two fasteners simultaneously. In one embodiment four fasteners are arranged with their axes of rotation spaced at 90 degree intervals on the circumference of a common circle, the diameters of the four associated toothed wheels being substantially equal and selected so that, in use, the toothed outer peripheries of each toothed wheel engage with a toothed outer periphery of a gear rotating mechanism which rotates on an axis passing through the centre point of the circle. Typically the toothed wheels associated with a first pair of diametrically opposed fasteners are axially displaced with respect to the second pair of diametrically opposed fasteners whereby, in use, the toothed wheels of the first pair can partly overlap the toothed wheels of the second pair of diametrically opposed fasteners. Advantageously the gear rotating mechanism can be designed so that the toothed outer peripheries of the toothed wheels of said first pair of fasteners can be engaged separately or simultaneously with the toothed outer peripheries of the toothed wheels of the second pair of fasteners. Preferably each of said toothed wheels have a composite structure comprising an inner wheel portion of a first material and an outer peripheral portion of a second material. Advantageously said outer peripheral portion is adapted to slip in one direction only relative to the inner wheel portion when a torque applied to the outer peripheral portion, relative to the inner wheel portion, exceeds a predetermined value. A stainless steel ring member may be provided on either side to retain a teflon annulus therein. According to another aspect of the present invention there is provided a motor vehicle wheel incorporating a system of toothed fasteners as hereinbefore described. Preferably said system of toothed fasteners is housed within the wheel and remains in the wheel even when it is removed from a vehicle axle. Advantageously the wheel is provided with an outer cover having a central aperture provided therein through which a toothed fastening tool can be inserted to be mechanically coupled to the toothed outer peripheries of said toothed wheels of the toothed fastener system. Typically the motor vehicle wheel further comprises a locking device adapted to be received in locking engagement with the toothed outer peripheries of said toothed wheels by insertion through said central aperture whereby, in use, said toothed wheels are prevented from turning by the locking device. Preferably the locking device is provided with a key operated latch means, said latch means preventing the device from being removed from the wheel through said central aperture when in a locked position. Preferably the friction reducing means is in the form of a fastener bearing assembly similar to that described in copending International Application No. PCT/AU92/00586 (FASTENER BEARING ASSEMBLY) or friction reducing means similar to that incorporated in the toothed fasteners described in International Application No. PCT/AU92/00393 (TOOTHED FASTENER) . The provision of friction reducing means greatly reduces the torque required to tighten or loosen the fasteners which facilitates a reduction in the diameter and strength of the toothed wheels and/or the number of fasteners required in a particular application, for example, a motor vehicle wheel, thereby making the use of gear wheels a more technically feasible and successful solution. Advantageously, all toothed surfaces of the system can be coated with an anti-corrosion, friction-reducing material, such as, for example, a Teflon based material. BRIEF DESCRIPTION OF THE DRAWINGS In order to facilitate a better understanding of the nature of the invention, a preferred embodiment will now be described, by way of example only, with particular reference to the accompanying drawings in which: Figure 1 is a plan view of one embodiment of the system of toothed fasteners according to the invention; Figure 2 is a side view of the system of toothed fasteners illustrated in Figure 1 with one of the fasteners and its associated toothed wheel removed for clarity; Figure 3 illustrates a motor vehicle wheel incorporating the system of toothed fasteners of Figure 1; Figure 4 illustrates the wheel of Figure 3 with an outer cover applied and a locking device inserted; Figure 5 is an enlarged view of one embodiment of the locking device employed in the wheel of Figure 4; Figure 6 is a modified version of the wheel illustrated in Figure 4; Figures 7, 8 and 9 illustrate the steps involved in threading a wheel fastener in one embodiment of the invention into the wheel flange of a motor vehicle; Figure 10 is a plan view of another embodiment of the system of toothed fasteners according to the invention; Figure 11 is a plan view of a still further embodiment of the toothed fastener system according to the invention; and, Figure 12 is a section view through an embodiment of a motor vehicle wheel incorporating a toothed fastener system according to the invention. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Figures 1 and 2 illustrate an embodiment of the toothed fastener system 10 according to the invention, which comprises a plurality of fasteners 12 each having a threaded portion 14 and a head portion 16 provided integral to the threaded portion. In the illustrated embodiment the fasteners are in the form of bolts 12, although in an alternative embodiment the fasteners may be in the form of nuts. The head portion 16 of each fastener 12 has associated with it a toothed wheel 18 having a toothed outer periphery 20. In this embodiment, the toothed wheels 18 are slidably received on the head portion 16 of the fasteners, the head portion and the toothed wheel being provided respectively with external and internal matching splines which engage to prevent the toothed wheels 18 from rotating relative to the respective head portions 16 of the fasteners 12. In an alternative embodiment (not illustrated) the toothed wheels 18 may be provided integral to the head portion of each fastener, or may be formed by the head portion itself suitably modified. For example, the head portion of the fasteners may be of enlarged diameter and provided with a toothed outer periphery so as to form a toothed wheel. The teeth on the toothed outer periphery 20 of the toothed wheels 18 are adapted to function like the teeth of a conventional gear wheel. Each of the fasteners 12 illustrated in Figures 1 and 2 are arranged so that the toothed outer peripheries 20 of the associated toothed wheels 18 of at least two of the fasteners can be simultaneously engaged, in use, by a gear rotating mechanism in the form of a toothed fastening tool 22. In the illustrated embodiment the toothed fastening tool 22 is shown engaging the toothed outer peripheries of all four of the toothed wheels 18 simultaneously, so that by rotating the fastening tool 22 all four fasteners can be tightened or loosened simultaneously. In this embodiment, the diameter of each of the toothed wheels 18 is approximately three times the diameter of the head portion 16 of the fastener, which is of a similar diameter to a conventional hexagon fastener of comparable size. Typically the diameter of each of the associated toothed wheels is between one to ten times the diameter of the head portion of a conventional fastener so that substantial mechanical advantage can be achieved using the toothed fastening tool 22 in view of the additional leverage and the large gear ratio. It is partly the mechanical advantage provided by the toothed wheels which enables two or more of the fasteners to be tightened or loosened simultaneously, without the torque required to turn the fastening tool becoming excessive. As can be seen most clearly in Figure 1, all four fasteners 12 are arranged with their axes of rotation spaced at 90 degree intervals on the circumference of a common circle 24, with the diameters of the four associated toothed wheels 18 being substantially equal and selected so that, in use, the toothed outer peripheries of each toothed wheel 18 engage with a toothed outer periphery 26 of the fastening tool 22 which rotates on an axis passing through the centre point 28 of the circle 24. Furthermore, in this embodiment the toothed wheels 18 associated with a first pair 30 of diametrically opposed fasteners are axially displaced with respect to the toothed wheels 18 associated with the second pair 32 of diametrically opposed fasteners, so that the toothed wheels 18 of the first pair 30 partly overlap the toothed wheels 18 of the second pair 32 of diametrically opposed fasteners. This arrangement means that the diameters of the toothed wheels 18 can be maximised without decreasing the number of fasteners or enlarging the diameter of the common circle 24, either of which may be unacceptable in some applications. A further advantage of this arrangement is that the toothed outer peripheries 20 of the toothed wheels 18 associated with the first pair of fasteners 30 can be engaged separately from the toothed outer peripheries of the toothed wheels of the second pair 32 of fasteners. Hence, if the torque required to tighten or loosen all four fasteners simultaneously is too great, the fastening tool 22 can be axially displaced to engage the toothed outer peripheries of the toothed wheels associated with one pair of fasteners prior to engagement with the toothed outer peripheries of the toothed wheels associated with the second pair. In an alternative embodiment all four toothed wheels 18 are axially displaced with respect to each other so that any one of the respective outer peripheries 20 of the toothed wheels can be engaged separately by the toothed outer periphery 26 of the tool 22. Obviously the fasteners 12 need not be arranged with their axes of rotation on the circumference of a common circle. Thus, for example, the diameter of the toothed wheels associated with the first pair of fasteners may be the same, with the first pair of fasteners having their axes of rotation on a first common circle, and the second pair of fasteners may have their axes of rotation on the circumference of a second common circle and have associated toothed wheels of a different diameter. Other possible combinations and arrangements will be obvious when it is remembered that there may be any suitable number of fasteners (at least two) , and that it is not necessary for the fastening tool to be able to always engage the outer peripheries of the toothed wheels on all of the fasteners simultaneously. Furthermore, a degree of freedom of travel in an axial direction of the toothed wheels, as well as the fasteners, may be incorporated in the system. In this embodiment of the invention, each of the toothed wheels 18 has a composite structure comprising an inner wheel portion 34 of plastics material and an outer peripheral portion 36 of metal. The composite structure of the toothed wheels 18 means they are relatively light-weight which may be importance in certain applications, for example, in motor vehicle wheels. Furthermore, the outer peripheral portion 36 can be adapted to slip in the tightening direction relative to the inner wheel portion 34 when a torque applied to the outer peripheral portion 36, relative to the inner wheel portion 34, exceeds a predetermined value. The minimum torque required to cause the outer peripheral portion 36 to slip can be set to equal the torque required to correctly pre-load or tension the fasteners 12 during tightening. If during tightening the applied torque exceeds the torque required to correctly tension the fasteners 12, continued rotation of the fastening tool 22 only causes the outer peripheral portions 36 of the toothed wheels 18 to slip relative to the inner wheel portion, thus preventing overtightening of the fasteners 12. The outer peripheral portions 36 of the toothed wheels 18 can slip in the direction of tightening only, and remain locked to the inner wheel portion 34 when the applied torque is in the loosening direction. In an alternative embodiment (not illustrated) a slip torque setting mechanism similar to that described above may be incorporated between the toothed wheels 18 and the head portion 16 of the fasteners, for example, by friction reducing means similar to that described in co-pending PCT/AU92/00393. An application of the embodiment of the toothed fastener system 10 illustrated in Figures 1 and 2 to a motor vehicle wheel will now be described with reference to Figures 3, 4, 5, 6, 7, 8 and 9. Figure 3 illustrates a motor vehicle wheel 40 incorporating a system 10 of four toothed fasteners as described above. In this embodiment the toothed fastener system 10 is housed within the wheel and is designed to remain in the wheel even when it is removed from a vehicle axle. The illustrated embodiment of the motor vehicle wheel 40 is of the modern cast alloy kind, and is provided with four fasteners having their axes of rotation arranged on the circumference of a common circle, in a manner substantially identical to the system 10 illustrated in Figures 1 and 2. The system 10 is housed within a circular recess 42 provided within the wheel 40 and has a cover 44 for enclosing and sealing the system 10 of toothed fasteners within the circular recess 42 of the wheel. The toothed wheels 18 are provided with a support plate 38 (see Figure 2) for rotatably supporting the wheels within the housing. Cover 44 is fastened to the wheel by means of fasteners which can only be accessed from the back or inner side of the wheel when the wheel is removed. A resilient material is provided between the edges of cover 44 and circular recess 42, for example a rubber O-ring, to seal the space within the circular recess 42 from both air and water. Cover 44 also provides security against theft since it cannot be removed without first removing the wheel, and the wheel cannot be removed without having the correct fastening tool. Cover 44 may be provided with a central aperture 46 as illustrated in Figure 4 to enable a suitable fastening tool to be inserted for engaging the toothed outer peripheries of the toothed wheels 18 of the toothed fastener system 10 housed within the wheel. Advantageously each of the fasteners 12 are provided with left-hand threads so that rotation of the fastening tool 22 in the normal tightening directions produces a counter-rotation of the fasteners also in the tightening direction. The fastening tool may be similar to the toothed fastening tool 22 illustrated in Figures 1 and 2 and may be provided with a handle similar to a conventional wheel brace to enable the tool to be rotated manually. The toothed head of the fastening tool may be separate from the handle and adapted to remain in the wheel with it's toothed outer periphery engaging the toothed outer peripheries 20 of the toothed wheels 18. When it is required to tighten or loosen the wheel fasteners the shaft of the fastening tool is inserted through aperture 46 and is adapted to engage in a central aperture provided in the toothed head of the tool to enable the latter to be rotated by the handle (not illustrated) . This arrangement has the advantage that the toothed head of the fastening tool can act as a locking device for the wheel by preventing the toothed wheels 18 of the fastener system 10 from loosening in use. Alternatively, as illustrated in Figures 5 and 6 the wheel can be provided with a locking device 48 which is received in locking engagement with the toothed outer peripheries of the toothed wheels 18 by insertion through the central aperture 46 so that, in use, the toothed wheels 18 are prevented from turning by the locking device 48. As can be seen most clearly in Figure 5 the locking device of this embodiment is in the form of a square- profile block 48 provided with two parallel splines 50 on each of it's side faces adapted to engage with the toothed outer peripheries 20 of the toothed wheels 18. The locking device 48 is provided with a key-operated latch means, (not shown) which prevents the device from being removed from the wheel through the central aperture 46 when in a locked condition. The latch means may be in the form of a pair of pivotally mounted lugs or palls provided in the locking device 48 and adapted to engage with the underside of the cover 44 in the locked condition. Advantageously the latch means is actuated by a key-operated lock 52 which is accessed by a key (not shown) through keyhole 54. When it is desired to remove the wheel the operator inserts a key into keyhole 54 and turns the lock 52 so that the latch means releases the locking device 48, which can then be removed through aperture 46 in the cover 44. A suitable fastening tool can then be inserted through aperture 46 to loosen the wheel fasteners. The provision of key-operated locking device 48 also enhances the security of the wheel against theft. The upper face of the locking device 48 may be shaped to fit snugly in the central aperture 46, and may be provided with an O-ring to provide a seal between the upper face of the locking device 48 and the central aperture 46 to prevent the ingress of water and other contaminants into the housing provided within circular recess 42. Advantageously the fasteners 12 and their associated toothed wheels 18 housed within the wheel are rotatably retained and correctly positioned in alignment with the respective wheel studs or holes provided in the wheel flange of the brake drum on the vehicle axle. Thus, for example, if each of the wheel fasteners 12 is in the form of a wheel bolt as illustrated in Figures 7 to 9, the floor of the circular recess 42 is provided with a suitable aperture 58 through which the threaded portion 14 of the fastener protrudes, and the underside of cover 44 is provided with four boss means (not shown) for rotatably receiving the upper side of the head portions of the respective fasteners. The toothed wheel 18 is slidably received on the head portion 16 of the fasteners, as illustrated in Figures 7 to 9, so that the fastener can be axially displaced relative to the wheel 40. In this way the wheel can be pushed onto a wheel flange 56 of the vehicle axle prior to starting the wheel fasteners on their respective threads 59 in the wheel flange 56. Advantageously, the wheel fasteners may be biased towards the inner side of the wheel so that, in the case of wheel bolts, the threaded portions 14 normally protrude from the inner side 66 of the wheel, but may be pushed in against the force of the biasing means. The means for biasing the wheel fasteners may be, for example, a coil spring 64 provided between a separate cone part 62 and the underside of the toothed wheel 18 of the fastener. This arrangement seals the fastener apertures 58 in the inner side of the wheel and prevents the ingress of water and other contaminants when the wheel is not in use. A similar arrangement can be achieved using wheel fasteners in the form of capped wheel nuts . The provision of biasing means simplifies alignment of the fasteners and starting on the threads when fitting the wheel to the wheel flange. Figures 7 through 9 illustrate the steps involved in correctly aligning a motor vehicle wheel 40 onto the wheel flange 56 of a motor vehicle, and subsequently starting the thread of the fastener on the thread 59 of the fastener aperture provided in the wheel flange 56. Figure 7 illustrates the wheel 40 having the threaded portion 14 of the fastener 12 protruding from the inner side 66 of the wheel. The threaded portion 14 protrudes due to the action of coil spring 64 in biasing the cone part 62 of the fastener, which is rotatably fixed on the spindle of the wheel bolt 12, against the cone shaped surface 68 of the fastener aperture 58 provided in the wheel. Incidently, in this embodiment the fastener aperture 58 is formed in a separate bush 72, which is press-fit into the wheel 40 and is made of a different material. In this condition, the head portion 16 of the wheel bolt 12 does not protrude beyond the inner support plate 38. Fastening ' tool 22 is provided with a central lug 74 which is rotatably received in a corresponding spigot or hole 76 in the wheel 40. Figure 8 shows how the wheel 40 is pushed against the wheel flange 56 with a central recess 78 of the wheel aligned with the axle hub 80 on the wheel flange 56. The threaded portion 14 of the wheel bolt 12 is aligned with the thread 59 in the wheel flange. In this condition, the threaded portion 14 is pushed back into the wheel 40 against the force of the spring 64. As rotation of fastening tool 22 commences the threaded portion 14 starts on the thread 59 in the wheel flange. The head portion 16 of the wheel bolt now protrudes beyond the inner support plate 38. If necessary, the head portion 16 may even extend beyond the outer cover 44 which can be provided with appropriate sealing means to prevent the ingress of dirt and water in use. Figure 9 illustrates the wheel bolt 12 in its tightened condition with its threaded portion 14 screwed into the thread 59 of the wheel flange. Coil spring 64 is now back in it's extended condition between the cone part 62 and the toothed wheel 18. The toothed fastener system 10 of the present invention is greatly enhanced by incorporating means for reducing friction between the head portion of the fasteners and the object to be fastened (eg. the wheel) , for example, a fastener bearing assembly similar to that described in copending International Application No. PCT/AU92/00586 (FASTENER BEARING ASSEMBLY), the contents of which are hereby incorporated by reference. PCT/AU92/00586 described a bearing assembly comprising a first part having a first pressure transmitting surface, and a second part having a second pressure transmitting surface adapted to rotatably receive the first pressure transmitting surface of the first part in facing relation thereto. Located between the first and second pressure transmitting surfaces is provided a solid dry lubricant material, typically in the form of an annulus of plastics material having a low coefficient of friction, such as teflon or a composite material containing teflon. The first part of the assembly is located with an upper face abutting against a lower face of the head of the fastener so that it can rotate with the head of the fastener, whereas the second part is located with a lower face abutting against the surface of the object to be fastened and can therefore be held stationary relative to the fastened object. The solid dry lubricant annulus provided between the first and second pressure transmitting surfaces therefore acts as a low-friction bearing between the head of the fastener and the fastened object and greatly reduces the turning friction between the head of the fastener and the object. Thus, in the present invention such a bearing assembly would be located between the under surface of the head portion 16 of the fasteners 12 and the floor of the circular recess 42 in wheel 40. Alternatively, each of the fasteners 12 may incorporate friction reducing means similar to that incorporated in the toothed fasteners described in International Application No. PCT/AU92/00393 (TOOTHED FASTENER) , the contents of which are incorporated herein by reference. PCT/AU92/00393 describes a toothed wheel fastener comprising a head portion provided integral to the threaded portion and having a toothed outer periphery and a pressure transmitting surface formed on an annular protrusion provided coaxial with the threaded portion of the wheel fastener. The wheel fastener incorporates a friction reducing means comprising a first part having a first pressure transmitting surface adapted to rotatably receive the pressure transmitting surface of the head portion in facing relation thereto. Typically the first part is in the form of an annular member having an annular recess provided therein, the width of the annular recess being slightly larger than the width of the annular protrusion provided on the head portion of the wheel fastener. Thus the annular member is free to rotate with respect to the wheel fastener, with the annular protrusion of the head portion slidably received within the annular recess of the annular member. A solid dry lubricant material in the form of a separate annulus of plastics material having a low coefficient of friction, is contained within the annular recess of the annular member adjacent the first pressure transmitting surface. The wheel bolt illustrated in Figures 7, 8 and 9 incorporates friction reducing means similar to that described in PCT/AU92/00393. The cone part 62 of the wheel bolt 12 is provided with an annular recess (not visible) in which is contained a solid friction reducing or dry lubricant material in the form of an annulus. The head portion 16 of the fastener is provided with an annular protrusion 70 (not clearly visible) which is rotatably received in the annular recess of the cone part 62 with the annulus of friction reducing material located therebetween. Preferably the cone part 62 is provided with radially extending teeth or ridges on its outer frusto-conical surface to grip the cone shaped surface 68 of the fastener aperture 58 in the wheel whereby the cone part 62 remains stationary relative to the wheel so that the annulus of friction reducing material can act as a bearing for the head portion 16 of the fastener when the fastener is tightened or loosened by rotating the toothed wheel 18. The provision of friction reducing means in the fasteners 12 of this embodiment of the system according to the invention enables a further reduction in the size and strength of the toothed wheels 18, since the torque required to tighten or loosen the fastener whilst still achieving the necessary clamping pressure can be greatly reduced. Thus, the toothed wheels 18 can have a relatively narrow thickness dimension, which facilitates the overlapping arrangement of the toothed wheels illustrated in Figures 1 and 2 within the constraints of the space provided within the wheel to house the toothed fastener system 10 of the invention. In one embodiment the toothed wheels extend into a space between the end of the axle hub and the wheel hub, however in some wheels this is not possible. In some situations there may be a concern that individual fasteners of the toothed fastener system 10 in the wheel are insufficiently tightened, or alternatively overtightened. In order to provide a visual indication to the user of the rotation of individual fasteners, the outer cover of the wheel may be formed with a plurality of apertures through which each fastener or an extension of each fastener is visible. Preferably an extension of each fastener protrudes through each aperture and each aperture is provided with an O- ring or similar sealing arrangement to prevent the ingress of dust or water into the wheel enclosure housing the toothed fastener system. Figure 6 illustrates a variation of the wheel illustrated in Figure 4, in which the cover 44 is provided with four additional apertures 60 adapted to enable a fastening tool to be inserted to engage the toothed outer peripheries of each of the toothed wheels associated with the four fasteners individually, in addition to the central aperture 46 through which the fastening tool can be inserted to engage the toothed outer periphery of one or more of the toothed wheels simultaneously. Figure 10 illustrates another embodiment of the toothed fastener system 10, which comprises a plurality of threaded fasteners (not illustrated) , each fastener having an associated toothed wheel 61. Each toothed wheel 61 is provided in connection with its associated fastener in such a manner that rotation of the associated toothed wheel 61 results in a corresponding rotation of the fastener. For example, the toothed wheel 61 may be formed integral to the head portion of the fastener, whether it be a nut or bolt. In this embodiment there are four fasteners uniformly arranged with their axes of rotation located on the circumference of a common circle 63. The toothed fastener system 10 further comprises a gear rotating mechanism 65 adapted to be mechanically coupled to the toothed wheels 61 associated with each of the four fasteners, and wherein the toothed wheels 61 are arranged so that the gear rotating mechanism 65 can be mechanically coupled simultaneously to at least two of the toothed wheels whereby, in use, the fasteners associated with the at least two toothed wheel 61 can be tightened and loosened simultaneously by operating the gear rotating mechanism 65. In this embodiment the gear rotating mechanism 65 comprises a fastening tool (not illustrated) having an associated toothed drive wheel 67. In the illustrated embodiment, the toothed fastener system 10 further comprises four toothed idler wheels 69, each idler wheel 69 being provided to mechanically couple the toothed drive wheel 67 to a corresponding toothed wheel 61 associated with each of the four fasteners. The idler wheels 69 are also arranged with their axes of rotation on a common circle, however each of the respective axes of rotation of idler wheels 69 is circumferentially offset with respect to the axis of rotation of the corresponding toothed wheel 61. This arrangement has been designed to allow the diameter of the idler wheels 69 to be slightly enlarged The main advantage of interposing idler wheel 69 between the drive wheel 67 and toothed wheel 61 of the fastener system 10, is that it enables the diameter of the drive wheel 67 and the toothed wheels 61 to be kept to a minimum, so that the total system 10 can be accommodated within the limited wheel space. A smaller diameter drive wheel 67 also provides greater mechanical advantage. Thus, for example, the toothed fastener system 10 of Figure 10 may be readily accommodated within a hub section of a conventional alloy motor vehicle wheel. The fastening tool employed with the toothed fastener system 10 may be similar to a conventional wheel brace or wrench which is adapted to be removably locatable in connection with the drive wheel 67 so as to cause the drive wheel 67 to rotate when a torque is applied to the tool. In this arrangement, the toothed drive wheel 67 is non-removable and remains rotatably mounted within the system 10. In an alternative arrangement the toothed drive wheel 67 is removable and is fixed to the end of the fastening tool and must therefore be inserted into the system 10 so that the drive wheel 67 engages each of the idler wheels 69 simultaneously. The toothed drive wheel 68 can be rotated on an axis of rotation passing through the centre of the common circle 63 in order to tighten or loosen the four fasteners simultaneously. Advantageously each of the idler wheels 69 lies in a common plane so that the entire fastener system 10 has a low profile and can be housed within a minimum space. However, it is also possible to have each of the idler wheels 69 axially displaced with respect to the other idler wheels so that one or more of the idler wheels 69 can be individually engaged without simultaneously engaging the other idler wheels 69. In this connection, the toothed drive wheel 67 may be one of several drive wheels provided on the fastening tool, each drive wheel being adapted to be mechanically coupled to a different one of the toothed wheels 61 via the idler wheels 69. In this way each of the fasteners can be tightened or loosened individually if desired. Furthermore, each drive wheel of the fastening tool may be provided with a clutch mechanism designed to cause the drive wheel to slip with respect to the tool when the torque applied to the drive wheel exceeds a predetermined maximum. Thus, torque will be transmitted from the tool to each of the fasteners via the respective drive wheels until the applied torque exceeds the predetermined maximum, and thereafter the tool slips and the respective drive wheel and fastener remain stationary while the remaining fasteners are similarly tightened. Alternatively, each fastener and its associated toothed wheel is provided with a clutch mechanism having a predetermined torque threshold before slipping, or slipping for one rotation and gripping again for subsequent tightening. Although in the illustrated embodiment, the gear rotation mechanism 65 comprises a toothed drive wheel which is located between the toothed wheels 61 associated with each of the fasteners, the gear rotation mechanism may also or alternatively comprise a ring gear located about an outer circumference of the fastener system, the ring gear having an inner peripheral toothed surface adapted to engage each of the toothed wheels 61. The ring gear may be provided with means for gripping so that it can be rotated by a suitable tool and/or manually. Figure 11 illustrates a still further embodiment of the toothed fastener system 10, in which like parts to that illustrated in Figure 10 have been given the same reference numerals. The system 10 of Figure 11 has five fasteners (not visible) on a common circle as on a conventional motor car wheel. Each fastener has an associated toothed wheel 61 with a toothed outer periphery mechanically coupled to a gear rotating mechanism 65. The gear rotating mechanism 65 comprises a large spur wheel or ring 71 which is driven by a smaller toothed drive wheel 67. One of the advantages of this embodiment is that each of the toothed wheels 61 associated with the respective fasteners will turn in the same direction as the drive wheel 67 in a tightening or loosening direction. A further advantage is the substantial mechanical advantage obtained due to the gear ratio of the drive gear 67 and the spur wheel or ring 71. In a still further embodiment, the toothed fastening means may comprise a toothed belt or chain arranged to engage the outer peripheral surfaces of the toothed wheels 61 which may be in the form of sprocket wheels. A suitable tensioning device may be provided whereby the tension on the belt or chain can be adjusted as required. In such an arrangement all of the sprocket wheels can be rotated simultaneously by rotating one of the sprocket wheels. This arrangement has the further advantage that it leaves the central hub area of the wheel free to receive the end of the axle. Each of the gear rotating mechanisms above described is adapted to be mechanically coupled to the toothed wheels associated with each of the plurality of fasteners, so that at least two of the toothed wheels can be tightened or loosened simultaneously by operating the gear rotating mechanism. A further embodiment of a motor vehicle wheel incorporating a toothed fastener system as described above, is illustrated in Figure 12. In this embodiment of a motor vehicle wheel 80, a toothed fastener system (not illustrated) is incorporated in a hub module 82 which can be fixed to a web 84 provided in connection with the rim 86 of the wheel 80. The wheel 80 is typically an alloy wheel and web 84 forms an outer cover of the vehicle wheel, and is typically in the form of a disc which radially transmits the load from the vehicle axle to the wheel rim 86. The disc 84 is provided with a central aperture 88 through which a fastening tool, as hereinbefore described, can be inserted to tighten or loosen the wheel fasteners (not illustrated) via the toothed fastener system housed within the internal space 90 of the hub module 82. The hub module 82 is fitted to the wheel disc 84 from an inner side of the wheel and is supported by a plurality of ribs 92 which extend from an inner surface of the wheel disc 84. The hub module 82 comprises a substantially cylindrical housing 94 having an outer circumferential surface 96 and a circular base portion 97. The ribs 92 extend along a substantial length of the outer circumferential surface 96 of the hub module 82, and help to transmit the load from the vehicle axle via the hub module 82 to the wheel disc 84, and hence to the wheel rim 86. The wheel disc 84 may be provided with an annular locating lip 98 for locating the cylindrical housing 94 of the hub module on the inner surface of the wheel disc 84. The cylindrical housing 94 may be fixed to the inner surface of the wheel disc 84 by suitable bolts extending through apertures provided in the wall of the housing, for example, along axes 100. When the hub module 82 is fixed to the wheel disc 84, the toothed fastener system (not shown) housed within space 90, is fully enclosed within the wheel with the only access provided by aperture 88. The cylindrical housing 94 of the hub module is provided with a plurality of apertures in the base portion 97 for the respective wheel fasteners (not illustrated) . Advantageously, the hub module is removably mounted on the wheel so that if necessary it can be removed (with the toothed fastener system housed therein) from the wheel. For example, when changing a tyre using a tyre changing machine, it is necessary to clamp the wheel to the machine. The hub module may be conveniently removed prior to clamping. The toothed fastener system located in space 90 may be in the form of any of the previously described embodiments of the fastener system, or may be specially designed for this application. Advantageously, each of the wheel fasteners housed within the hub module 82 is spring-loaded, to assist with correctly aligning and starting the fasteners on their respective threads. Each of the wheel fasteners may be provided with a compression and/or torsion spring, the compression spring ensuring that each of the fasteners can be started on the thread of the respective wheel bolt or stud, and the torsion springs being pretensioned in order to automatically apply a torque to each of the wheel fasteners when they have been correctly located on the wheel flange of the vehicle axle. The fastener system may be provided, for example, with a trigger mechanism whereby when the wheel has been correctly located each of the respective torsion springs can be released in order to automatically screw the fasteners onto the wheel flange of the vehicle brake drum or axle. This leaves the user's hands free to hold the wheel in an aligned position. Such a trigger mechanism may comprise, for example, a projecting pin adjacent each fastener. The concept of having each wheel fastener spring- loaded is not necessarily restricted in its application to a toothed fastener system according as described above. For example, each of the wheel fasteners on a conventional wheel could be provided with a spring to assist in correctly aligning and starting the fasteners on the threads, each fastener being individually held on the wheel by a housing or its own cage. Each of the internal surfaces of 104 of the enclosure formed by the housing 94 and the wheel disc 84, may act as bearing surfaces for the toothed wheels, threaded fasteners, bearing assemblies, idler wheels and drive wheel of the toothed fastener system housed within the space 90. Alternatively, all bearing surfaces for the fastener system may be provided in the hub module 82, which therefore functions independently from the wheel. In the illustrated embodiment of Figure 12, the base portion 97 of the hub module 82 is provided with a central recess .106 adapted to receive the end of the vehicle axle and to transmit most of the vertical load from the vehicle axle to the hub module. Therefore, the wheel fasteners are only required to withstand an axial load, providing the clamping pressure which clamps the wheel to the vehicle axle. A conventional motor vehicle wheel of comparable size normally requires at least five wheel fasteners per wheel in order to obtain the required clamping pressure on the wheel as determined by the working load and the practical limits on the size of the fasteners. The size of the fasteners in a conventional wheel is limited by the type of fastening tool and the magnitude of the torque required to tighten or loosen the fastener whilst still obtaining the necessary clamping pressure or pre-load tensioning of the fasteners. Thus, for example, if four conventional fasteners were employed on a conventional motor vehicle wheel they would need to be larger than the conventional wheel fasteners currently employed and would require significantly more torque to tighten and loosen due to the increased friction between the fasteners and the wheel and the increased torque required to achieve the increased pre¬ load. However, by incorporating friction reducing means in the fasteners of the toothed fastener system 10 in the motor vehicle wheel 40, the torque required to achieve the same pre¬ load can be reduced by at least 50% and therefore larger but fewer wheel fasteners can be employed to achieve the same hold- down or clamping pressure, together with cost and time savings. The required torque can be further reduced by coating the threads and teeth of the fasteners and toothed wheels with a friction reducing material or solid lubricating material, for example, a Teflon-based material. Thus the system employing four fasteners as illustrated in the drawings can replace a conventional wheel which employs at least five conventional wheel nuts or bolts. It will be evident from the above description of preferred embodiments of the toothed fastener system 10 and a motor vehicle wheel 40 incorporating same that the system provides significant advantages over conventional fasteners. In it's application to a motor vehicle wheel the toothed fastener system 10 facilitates rapid tightening and loosening of the wheel fasteners, and therefore simplifies the procedure for removing a wheel from the vehicle. As the fastener system advantageously remains housed in the wheel, automatic fastener alignment and positioning facilitates rapid wheel replacement. In addition, by housing the system within the wheel improved security can also be achieved due to the limited access and unique tool required to rotate the fasteners and their associated toothed wheels. The inclusion of friction reducing means further enhances the advantages of the toothed fastener system over conventional fasteners by greatly reducing the friction and therefore reducing the torque required to correctly tension the fasteners. Furthermore, and importantly, the friction reducing means enables all of the fasteners to be correctly tensions to the required pre-load. With prior art wheel fastener systems there is a danger that some fasteners remain under-tightened whilst others are over-tightened, as the frictional forces tend to vary from fastener to fastener. A wheel incorporating a toothed fastener system with friction reducing means can be fastened by one person using the same torque required to tighten or loosen a single conventional wheel fastener. It will be obvious that numerous modifications and variations may be made to the illustrated embodiments, in addition to those already described, without departing from the basic inventive concepts. For example, although the motor vehicle wheel in the illustrated embodiment is of the modern cast alloy type, the invention is equally applicable to the older pressed metal type motor vehicle wheels. With the latter type of wheel a suitable housing would be provided to cover the toothed fastener system and is securely fastened to the wheel in a similar manner to the cover 44 of the described embodiment. The illustrated embodiment is arranged with the toothed fastener system 10 located in the limited space provided between the end of the axle hub and the outer extremity of the wheel, generally defined by a plane flush with the outer edge of the tyre provided on the wheel. The head portion of the fasteners in the described embodiments are provided with splines for engaging with the toothed wheel. However, obviously the head portion of the fastener may be of any suitable configuration, for example hexagonal or with a single key and matching key-way, and the gear wheels adapted to engage with the head portion so as to normally prevent the toothed wheel from rotating relative to the head portion. Alternatively, a separate sleeve or hollow extension piece may be provided for each fastener within which the head portion is axially movable, the toothed wheel being received on an outer circumference of the hollow extension piece. With this arrangement the head portion of the fastener may be of conventional hexagonal configuration and a spring may be accommodated within the hollow extension piece to bias the fastener against the wheel. A clutch mechanism may be provided between the hollow extension piece and the associated toothed wheel. All such variations and modifications are to be considered within the scope of the present invention, the nature of which is to be determined from the foregoing description and the appended claims.

Claims: THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS: 1. A system of toothed fasteners for fastening an object, the system comprising: a plurality of fasteners each having a threaded portion and a head portion provided integral to the threaded portion, said head portion of each fastener having associated with it a toothed wheel having a toothed outer periphery, wherein the teeth of the toothed outer periphery are adapted to function like the teeth of a conventional gearwheel whereby, in use, the toothed outer periphery of each toothed wheel can be engaged laterally for transmitting a torque to its associated fastener; each fastener being provided with friction reducing means comprising a solid dry lubricant material contained within a region between the head portion of the fastener and the object whereby, in use, the solid dry lubricant material can act as a low-friction bearing for the fastener; and wherein said fasteners are arranged so that the toothed outer peripheries of the associated toothed wheels of at least two of the fasteners can be simultaneously mechanically coupled to a gear rotating mechanism whereby, in use, said at least two fasteners can be turned in a tightening or loosening direction simultaneously by operating the gear rotating mechanism. 2. A system of toothed fasteners as claimed in claim 1, wherein the head portion of each fastener is axially movable relative to the associated toothed wheel, there being provided engaging means for normally preventing the toothed wheel from rotating relative to the head portion. 3. A system of toothed fasteners as claimed in claim 1, wherein four fasteners are arranged with their axes of rotation spaced at 90 degree intervals on the circumference of a common circle, the diameters of the four associated toothed wheels being substantially equal and selected so that, in use, the toothed outer peripheries of each toothed wheel engage with a toothed outer periphery of a gear rotating mechanism which rotates on an axis passing through the centre point of the circle. 4. A system of toothed fasteners as claimed in claim 3, wherein the toothed wheels associated with a first pair of diametrically opposed fasteners are axially displaced with respect to the second pair of diametrically opposed fasteners whereby, in use, the toothed wheels of the first pair can partly overlap the toothed wheels of the second pair of diametrically opposed fasteners. 5. A system of toothed fasteners as claimed in claim 1, wherein each of said toothed wheels have a composite structure comprising an inner wheel portion of a first material and an outer peripheral portion of a second material. 6. A system of toothed fasteners as claimed in claim 1, wherein each fastener and its associated toothed wheel is provided with a clutch mechanism having a predetermined torque threshold and designed to allow the toothed wheel to slip with respect to the associated fastener when the torque applied to the toothed wheel exceeds said predetermined torque threshold. 7. A system of toothed fasteners as claimed in claim 1, wherein said gear rotating mechanism comprises a plurality of toothed idler wheels and a single toothed drive wheel, each idler wheel being interposed between the drive wheel and a corresponding toothed wheel associated with each fastener. 8. A motor vehicle wheel within which a toothed fastener system as claimed in any one of claims 1 to 7 is incorporated, and wherein said toothed fastener system remains on the wheel even after it is removed from a vehicle axle. 9. A motor vehicle wheel as claimed in claim 8, wherein the wheel is provided with an outer cover having a central aperture provided therein, and wherein said gear rotating mechanism comprises a toothed fastening tool that can be inserted through said central aperture to be mechanically coupled to the toothed outer peripheries of said toothed wheels of the toothed fastener system. 10. A motor vehicle wheel as claimed in claim 9, further comprising a locking device adapted to be received in locking engagement with the toothed outer peripheries of said toothed wheels by insertion through said central aperture whereby, in use, said toothed wheels are prevented from turning by the locking device. 11. A motor vehicle wheel as claimed in claim 8, wherein the toothed fastener system is housed within a hub module removably mounted on the wheel. 12. A motor vehicle wheel as claimed in claim 11, wherein said wheel comprises a web forming an outer cover of the wheel and adapted to transmit a load from the vehicle axle radially to a rim of the wheel, and wherein said hub module is mounted on an inner side of the wheel and is supported by a plurality of ribs which extend from an inner surface of the web. 13. A motor vehicle wheel as claimed in claim 8, wherein said wheel is provided with an outer cover for covering an enclosure within which the toothed fastener system is housed, and wherein each fastener in the toothed fastener system is provided with an extension, each extension being visible through a corresponding aperture in the outer cover to provide a visual indication of the fasteners turning during tightening and loosening. 14. A motor vehicle wheel as claimed in claim 8, wherein each of the wheel fasteners are provided with biasing means for biasing the fastener towards an inner side of the wheel whereby, in use, each fastener can be correctly aligned and started on a corresponding thread on the vehicle axle. 15. A motor vehicle wheel as claimed in claim 14, wherein said biasing means is in the form of a coil spring provided between the associated toothed wheel and the wheel.

Inventors: MATTHEWS NORMAN LESLIE, MATTHEWS, NORMAN, LESLIE
Applicants: MATTHEWS NORMAN LESLIE, MATTHEWS, NORMAN, LESLIE
Application year: 1993
Main classification: B60B3
IPC codes: B60B3, F16B39