GB2518170A

GB2518170A - A turnbutton fastener

Info

Publication number: GB2518170A
Application number: GB1316206.0A
Authority: GB
Inventors: Dietmar Jochum
Original assignee: MINI CAM Ltd
Current assignee: MINI CAM Ltd
Priority date: 2013-09-11
Filing date: 2013-09-11
Publication date: 2015-03-18
Anticipated expiration: 2033-09-11
Also published as: GB2518170B; GB201316206D0

Abstract

A turnbutton fastener comprises a non-cylindrical shaft 5, a latch 9 rotatably mounted on an end of the shaft 5, and a helically threaded fastener 11 securing the latch 9 to the shaft 5. The threaded fastener 11 is adjustable between a loosened position and a tightened position. In the loosened position the threaded fastener 11 is in frictional engagement with the latch 9 so that the latch 9 rotates when the threaded fastener 11 is turned. In the tightened position, the latch 9 engages directly or indirectly with the shaft 5 to prevent relative rotation between the latch and the shaft.

Description

A TURNBUTTON FASTENER

Technical Field of the Invention

The present invention relates to quick-release fasteners suitable for coupling a wheel to an axle.

Background to the Invention

The wheels of land vehicles, such as road vehicles and unmanned inspection vehicles, are commonly attached to a hub or ax'e using screws. Repbcing a wheel therefore typically entails removal and re-insertion of multiple screws, which is time consuming and can result in removed screws, washers, or other small parts becoming lost. In certain applications, such as unmanned pipework inspection vehides and off-road vehicles, wheel replacement may be required when the component parts are already coated in sludge such as sewage, oil, or mud, and are therefore slippery and visually indistinct, so small parts such as screws and washers may be particularly difficult to handle, easily dropped or misplaced, and virtually impossible to then locate in a sludgy andlor hazardous environment. There are of course many other applications where removable fasteners of any sort, such as screws, may be difficult to handle and easy to lose. In any such cases, it may be preferable to provide a suitably strong and reliable fastening means which is operable as simply and quicldy as possible and without the removal of screws or other small parts.

Quick-rdease levers, such as those commonly used to secure a wheel to the frame of a bicycle, are an example of such a fastening means. However, they may be unsuited to many uses. For example, such a quick-release fastener prevents removal and replacement of parts in an axial direction; rather, a bicycle wheel must be inserted to the frame in a radial direction, which may not be appropriate in other applications, such as attaching a wheel to a motor or drive axle. Furthermore, such a fastening means may be too bulky or insufficiendy robust for many uses, may prevent a hazard or snagging risk such as when protruding from the wheel of a motor vehicle, and may require dexterity, skill, and judgement to ensure that it is adequately tightened.

Accordingly, objects of embodiments of the present invention therefore include the provision of a robust and secure fastener that is quiclc, easy, and intuitive to fasten and unfasten, even under slippery and/or low-visibility conditions, and that is operable without the removal or detachment of its parts.

Summary of the Invention

According to a first aspect of the invention, there is provided a latch for a turnbutton fastener, the latch comprising a latch body with a non-cylindrical cross section. a helically threaded fastener for rotatably fastening the latch to an object, a resilient member, and friction member, wherein the threaded fastener comprises a head that is constrained between the resilient member and the friction member.

The head may be constrained on opposite sides by the resilient member and the friction member, and may be constrained in an axial direction by the resilient member and the friction member.

The resilient member may be a spring, which may be a spring washer such as a split ring washer, a conical washer, or a curved-disc or wave washer, and may be interposed between the threaded fastener and the latch body.

The friction member may be a resilient, high-friction pad, may be interposed between the threaded fastener and the latch body, may comprise an elastomer such as a natural or synthetic rubber, and may comprise an annular ring, such as an 0-ring.

The threaded fastener may comprise a substantially domed or frusto-conical surface portion, and may be a screw, such as a socket-head cap-screw. For example, the threaded fastener may be a button-head screw or a tapered-head screw.

According to a second aspect of the invention, there is provided a tumbutton fastener comprising a non-cylindrical shaft, a latch rotatably mounted on an end of the shaft, and a helically threaded fastener securing the latch to the shaft, wherein the threaded fastener is adjustable between a loosened position, in which the threaded fastener is in frictional engagement with the latch so that the latch rotates when the threaded fastener is turned, and a tightened position, in which the latch engages directly or indirectly with the shaft to prevent relative rotation between the latch and the shaft.

A turnbutton fastener may be easy and intuitive to operate, and may be securely fastened by the helically threaded fastener such as a locking screw. Furthermore, the frictional engagement between the turnbutton latch and the threaded fastener causes the latch to turn with the threaded fastener so that the operator need not turn the threaded fastener any further than necessary to rotate the latch between an openlunfastened and a closed/fastened position and back again. The rotation-limiting engagement between the shaft and latch permits the threaded fastener to be securely tightened without causing further rotation of the latch relative to the shaft, so that when the turnbutton fastener is securely fastened, any torque acting on the shaft and/or latch would not induce loosening of the helical fastener, and slight loosening of the helical fastener would not induce rotation of the latch relative to the shaft.

When the threaded fastener is in said tightened position, the latch may be resiliently biased against the threaded fastener towards the shaft, and may engage directly or indirectly with the shaft via interlocking contact. In said tightened position, the threaded fastener may be released from said frictional engagement with the latch, and may clamp the latch agal list the shaft.

The tumbutton fastener may comprise a resilient member, such as a spring, arranged to bias the latch towards the shaft. This may be a spring washer, such as a split ring washer, a conical washer, or a curved-disc or wave washer. The resilient member may be interposed between the threaded fastener and the body of the latch.

When the threaded fastener is in said loosened position, the latch may be resiliently biased against the threaded fastener away from the shaft.

The turnbutton fastener may comprise a resilient, high-friction pad arranged to bias the latch away from the shaft, which may be interposed between the threaded fastener and the latch, may comprise an elastomer such as a natura' or synthetic rubber, and may comprise an annular ring, such as an 0-ring.

Respective cross sections of the shaft and the latch may share an identica' shape or substantially the same shape, and may be bounded by an identica' outline or by substantially the same outline. One or both of the latch and the shaft may have a rotationally symmetric cross section, may have a cross section substantially defined by a regular polygon, may have a cross section substanfially defined by a regular polygon with rounded-off corners. may have a cross section substantially defined by a plurality of circular arcs spanning and extending continuously from alternate sides of an even-sided regular polygon, and may have a cross section substantially defined by an outline of the form cos(nO) r=a+b (n+fl(n-1) where r and 0 are radial and angular positions about the central axis of the shaft, n is an integer greater than or equal to 2, and b/a is non-zero with a magnitude preferably between 0,5 and 4, more preferably between 0.7 and 3, more preferably between 0.9 and 2, and more preferably between 1.0 and 1.5.

In a preferred embodiment, each of the latch and the shaft has a cross section with rotational symmetry, substantially defined by an equilateral triangle with rounded-off corners, by three circular arcs extending between alternate sides of a regular hexagon, IS and approximately by an outline of the form described above where n = 3 and b/a has a value of about 1.2.

The turnbutton fastener may be arranged to Umit relative rotation between the latch and the shaft by a predefined angle. The shaft and latch may each have a rotationally symmetric cross section with a rotation symmetry angle which is twice said predefined angle to which relative rotation is limited.

The latch and the shaft may overlap one another by an area substantially defined by an even-sided regular polygon when the threaded fastener is in its tightened position, and may overlap one another by an area substantially equal to a cross section of at least one of the latch and the shaft when the threaded fastener is in its loosened position.

The shaft may form part of an axle to which a rotating part is attachable, may form part of a wheel axle of a motor vehicle, such as a remote-controlled pipe inspection vehicle.

According to a third aspect of the invention, there is provided an eye for use with such a turnbutton fastener, the eye comprising a through-hole having a non-circular bore shape and one or more shallow recesses in a suiface of the eye, the one or more recesses being arranged to captively engage an object having a footprint substantially the same size and shape as the non-circular bore.

The through-h&e may have a rotationally symmetric bore shape, may have a bore shape section substantially defined by a regular polygon, may have a bore shape substantially defined by a regular polygon with rounded-off corners, may have a bore shape substantially defined by a p'urality of circular arcs spanning and extending continuously from alternate sides of an even-sided regular polygon, and may have a bore shape substantially defined by an outline of the form cos(nG) r=a+b (n+1)(n-1) where rand 0 are radial and angular positions about a central axis of the through-hole, n is an integer greater than or equal to 2, and h/a is non-zero with a magnitude preferably between 0.5 and 4. more preferably between 0.7 and 3, more preferably between 0.9 and 2, and more preferably between 1.0 and 1.5.

In a preferred embodiment, the through-hole has a bore shape with rotational symmetry, substantially defined by an equilateral triangle with rounded-off corners, by three circular arcs extending between alternate sides of a regular hexagon, and approximately by an outline of the form described above where n = 3 and h/a has a value of about 1.2.

The eye may form part of a rotating part attachable to an axle. may form part of a wheel, and may form the hub of a wheel for a motor vehicle, such as a remote-controlled pipe inspection vehicle.

According to a fourth aspect of the invention, there is provided a vehicle having a wheel axle that comprises a turnbutton fastener as described above. The vehicle may also include a wheel comprising an eye as described above and secured to the wheel axle by the turnbutton fastener.

According to a fifth aspect of the invention, there is provided a method of unfastening a turnbutton fastener as described above, the method induding the step of turning the threaded fastener, wherein turning the threaded fastener is effective to unclamp the latch from the shaft, to engage the latch in frictional contact with the threaded fastener, and to rotate the atch with the threaded fastener from a locked position into an unlocked position.

According to a sixth aspect of the invention, there is provided a method of fastening a turnbutton fastener as described above, the method including the step of turning the threaded fastener such that the latch rotates with the threaded fastener from an unlocked position into a locked position, disengages from frictional contact with the

S

threaded fastener, and engages directly or indirectly with the shaft to exert a clamping force.

Features of any aspect of the invention may be combined interchangeably with any other aspect of the invention.

Detailed Description of the Invention

In order that the invention may be more clearly understood, an embodiment thereof will now be described, by way of example only, with reference to the accompanying drawings. of which: Figure 1 is a perspective view of a wheel and a wheel connector according to the present invention; Figure 2 is a cut-away perspective view of the wheel and connector of Figure I engaged in a locked position; Figure 3 is an exploded cross-section of the wheel and connector of Figure 1; Figure 4 is an end elevation of the connector of Figure 1; FigureS shows an end elevation and a perspective view of a shaft forming part of the connector of Figure i; and Figure 6 shows a number of elevations and perspective views of an end cap forming another part of the same connector.

A preferred embodiment of the present invention is illustrated in Figures ito 6, in which a locking wheel connector I forms part of a motor-driven wheel axle 2 of a remote-control pipe inspection vehicle. The wheels of a pipe inspection vehicle must be readily replaceable to allow use of a range of modular wheel sizes in different diameters of pipe, so it is useful to provide a simpiy operable, quick-release connector that remains intact during removal and replacement of a wheel.

The connector 1 has a prism-shaped shaft portion 5 which is slidably engageable with a correspondingly shaped opening 7 bored through the centre of the wheel 3. The shaft and matching opening are non-cylindrical and close-fitting, since the axle 2 must transfer torque to the wheel 3. Mounted on the end of the prism-shaped shaft portion 5 is an end cap 9 which also has the same cross-section shape as the prism-shaped shaft portion 5. The end cap 9 is rotatable relative to the shaft and is fastened to the shaft by a central screw 11, the head of which is set within a recess 13 in the end cap 9.

The matching cross sections of the shaft portion 5. the end cap 9, and the opening 7 in the wheel 3 allow the end cap and shaft to be rotationally aligned so that the wheel can be freely slid on and off the shaft, as illustrated in Figure 1. The end cap 9 can then be twisted out of rotational alignment with the shaft portion 5 so that the wheel is secured to the shaft. Thus, the end cap 9 forms the latch of a turnbutton fastener and the hub of IS the wheel 3 functions as an eye fastenable to the turnbutton fastener.

The construction of the connector can be seen more clearly in Figure 3, and the shapes of the shaft portion and end cap are further illustrated in Figures 5 and 6 respectively. The shaft portion S has a threaded bore 15 to receive the screw 11 and a non-circular counter-bore i 7 forming a recess in its end face 19 to receive a protruding part 2lof the end cap. The recess 17 and protruding part 21 engage with one another to form a rotation-limiting stop that permits relative rotation of the shaft and end cap within a predefined angular range only. In one embodiment, the recess 17 has the general shape of a cylinder 23a with a minor segment 25a removed, as illustrated in FigureS. As can be seen in Figure 6, the protrusion 21 has the general shape of the same-sized cylinder 23b with the same-sized minor segment 25b removed at two angular positions 27 about the cylinder and at all intervening angular positions therebetween, the two angular positions being spaced by the predefined angle 29 to which rotation is to be limited. However, any suitaNe shapes and engaging parts may be provided to form such a rotation-I imiting stop.

Rotation is limited between an open or unlocked position as shown in Figure 1 and a closed or locked position as shown in Figure 2 and 4, where the open and closed positions are separated by the predefined angle 29 which is preferably equal to half of the angle of rotational symmetry 31 of the prism-shaped shaft portion 5.

In the embodiment illustrated, the shaft portion 5, end cap 9, and wheel opening 7 each has cross-section shape that can be viewed as an equilateral triangle with rounded-off corners or, as can more clearly be seen in Figure 4, as a regular hexagon 33 with circular arcs 35 extending from alternate sides of the hexagon. The outline of the cross-section shape can be approximated by a curve having the polar equation cos(38) r=a+b 8 where h/a has a value of approximately 1.2. The angle of rotational symmetry 31 of the cross section is 120 degrees, and the permitted range of relative rotation 29 is 60 degrees.

The screw 11 rests against a conical spring washer 37 interposed between the screw head 39 and a surface of the recess 13 in the end cap 9, so that the end cap is biased against the screw head towards the shaft 5 when the screw is sufficiently tightened. A circumferential channel 41 in the recess 13 of the end cap 9 accommodates a rubber 0-ring 43 which can be inserted thereto when the screw is sufficiently tightened.

When the screw is fully tightened, the spring washer is fully compressed and the screw head 39 does not contact the 0-ring 43. As the screw is retracted, the spring washer 37 continues to urge the end cap 9 towards the shaft 5, so that the 0-ring is brought into contact with the screw head 39 to establish frictional contact between the screw and the end cap. Once the screw is sufficiendy retracted, its pressure against the 0-ring lifts the end cap from the end of the shaft, and its frictional contact with the 0-ring causes the end cap to rotate with the screw as far as permitted by the rotation-limiting stop. Thus, rotation of the end cap to the open position, i.e. unlocking the turnbutton fastener, happens automatically as the screw is loosened and serves as a clearvisual indicator that the screw is sufficiently loose and need not be turned any further in order to install or remove a wheel.

The wheel 3 is provided with shallow, crescent-shaped recesses 45 conforming to the regions 47 of the end cap that overhang the shaft in the locked configuration. Since the wheel is rotationally constrained relative to the axle by close-fitting engagement with its non-cylindrical portion 5. the end cap 9 is similarly constrained while it is engaged with the shallow recesses 45 in the wheel. Thus, while the screw is sufficiently tightened that the end cap remains engaged with the crescent-shaped recesses 45, the end cap cannot be rotated by tightening or loosening the screw. This prevents the latch from opening even when the screw is not quite fully tightened, and prevents any external loading to the end cap from acting to loosen the screw.

To protect the end cap from external loading, whether from a harsh environment or from a misguided attempt to manually tighten it with a spanner or wrench, its external shape comprises a generally frusto-conical or domed surface Si. Moreover, the end cap sits within a protective well or rim 53 on the wheel. These features help to minimise external protruding edges that could snag or jam against an obstacle, and reduces the likelihood of the end cap being mistaken for a tightenable nut.

In the arrangement shown, shallow recesses 45 are machined into the wheel only.

Alternatively, or in addition, a shallow recess may be machined into the end face 19 of the shaft to leave a set of slightly protruding flat lugs at the extremities of the shaft end face, each of which may have the same crescent shape as the shallow recesses 45 illustrated on the wheel surface. It is preferred that the end cap damps the wheel firmly against an opposing surface 46 of the shaft, although clamping the end cap directly to the shaft without applying any pressure to the wheel may be acceptable provided that the wheel is securely constrained in place.

The screw 11 is a button-head or taper-head screw adapted to receive a hex key, although other types of key or screwdriver head may be suitable. The domed or conical surface 49 of the screw head 39 provides a circumferential space that allows the 0-nng 43 to be easily inserted into the channel 41 in the end cap recess 13 once the screw is IS sufficiently tight. As the screw is loosened and comes into contact with the 0-ring, its domed or conical surface 49 engages gradually with the 0-ring 43 to establish an interference fIt and to progressively increase the transfer of torque to the end cap 9.

The geometry of the end cap 9 and the screw head 39, the pitch of the screw thread, the size and stiffness of the 0-ring 43 and the spring washer 37, and the depth of the shallow recesses 45 on the wheel are selected to ensure that the screw must be turned by only a minimal amount in order to fully open or close the turnbutton fastener. In a preferred arrangement. tightening the screw by just one turn is sufficient to spin the end cap 9 from the unlocked position into the locked position, compress the spring washer 37 and disengage frictional contact between the screw and the 0-ring 43, engage the end cap within the shallow recesses 45 on the wheel, and clamp the end cap securely to the axle 2 and/or the wheel 3; similarly, loosening the screw by one turn is effective to unclamp the end cap and disengage it from the shallow recesses, unload the spring washer, engage frictional contact between the screw and 0-ring, and finally spin the end cap from the locked position into the unlocked position.

Thus, the turnbutton fastener arrangement requires minimal intervention to release or install the wheel, provides a clear indication of when to stop loosening the screw, and does not require any parts to be added or removed other than the wheel itself.

It is extremely compact, having an external appearance that resembles little more than a nut or an oversized screw head.

The wheel hub, shaft, end cap, spring washer, and screw ale all preferably fabricated from stainless steel or another corrosion-resistant alloy, and the 0-ring from a synthetic rubber suitable for use in a conosive and/or hydrocarbon-rich environment, IS such as a fluoroelastomer.

Although the embodiment shown relates to a remote-controlled pipe inspection vehicle, it will be appreciated that such a turnbutton connector may be usef& in a wide variety of other applications. It may for example be used as an axial fastener for wheels or other rotating parts where torque transmission is required, or simply as a fastener that prevents relative rotation of the fastened parts, although more generally it may be useful anywhere that a simple, convenient, and robust fastener is required. Its simplicity and ease of operation provide advantages that will be apparent anywhere that speed and ease of use are important, such as in motor racing, quick-release bicycle components, temporary and deployable structures, and any parts that must be installed, adjusted, or repaired in a time-critical or hazardous environment.

The above embodiment is descnbed by way of example only. Many variations are possible without departing from the scope of the invention as defined in the appended claims.

Claims

CLAIMSI. A turnbutton fastener comprising a non-cylindrical shaft, a latch rotatably mounted on an end of the shaft, and a helically threaded fastener securing the latch to the shaft, wherein the threaded fastener is adjustable between a loosened position, in which the threaded fastener is in frictional engagement with the latch so that the latch rotates when the threaded fastener is turned, and a tightened position, in which the latch engages directly or indirectly with the shaft to prevent relative rotation between the latch and the shaft.
2. A turnbutton fastener according to dairn I wherein the latch is resiliently biased against the threaded fastener towards the shaft when the threaded fastener is in said tightened position.
3. A turnbutton fastener according to claim I or 2 wherein the latch engages directly or indirectly with the shaft via interlocking contact when the threaded fastener is in said tightened position.
4. A turnbutton fastener according to any preceding claim wherein, in said tightened position, the threaded fastener is released from said frictional engagement with the latch.
5. A turnbutton fastener according to any preceding claim wherein, in said tightened position, the threaded fastener clamps the latch against the shaft.
6. A turnbutton fastener according to any preceding claim comprising a spring arranged to bias the latch towards the shaft.
7. A turnbutton fastener according to claim 6 wherein the spring is a spring washer.
8. A turnbutton fastener according to any preceding claim wherein the latch is resiliently biased against the threaded fastener away from the shaft when the threaded fastener is in said loosened position.
9. A tumbutton fastener according to any preceding claim comprising a resilient, high-friction pad arranged to bias the latch away from the shaft.
10. A turnbutton fastener according to claim 9 wherein the resilient, high-friction pad is an O-nng.
II. A turnbutton fastener according to any preceding claim wherein the threaded fastener comprises a substantially domed or frusto-conical surface portion.
12. A turnbutton fastener according to any preceding claim wherein the threaded fastener is a screw.
13. A turnbutton fastener according to any preceding claim wherein respective cross secions of the shaft and the latch have substantially the same shape.
14. A turnbutton fastener according to any preceding claim wherein at least one of the latch and the shaft has a rotationally symmetric cross section.
15. A turnbutton fastener according to any preceding claim wherein at least one of the latch and the shaft has a cross section substantially defined by a regular polygon with rounded-off corners.
16. A turnbutton fastener according to any preceding claim arranged to limit relative rotation between the latch and the shaft to a predefined angular range.
17. A turnbutton fastener according claim 16, where dependent directly or indirectly on claim 14, wherein said predefined angular range is half of the rotafion angle of the rotationally symmetric cross section.
18. A turnbutton fastener according to claim 16 or 17 wherein said predefined angular range is 60 degrees.
19. A turnbutton fastener substantially as herein described with reference to the appended figures.
20. A latch for a turnbutton fastener, the latch comprising a non-cy'indrical latch body, a helically threaded fastener for rotatably fastening the latch to an object, a resilient member, and a friction member, wherein the threaded fastener comprises ahead that is constrained between the resilient member and the friction member.
21. A latch according to daim 20 wherein the resilient member is a spring.
22. A latch according to claim 20 or 21 wherein the friction member is a resilient, high-friction pad.
23. A latch according to any one of claims 20 to 22 wherein the threaded fastener comprises a substantially domed or frusto-conical surface portion.
24. A latch for a tumbutton fastener, the latch being substantially as herein described with reference to the appended figures.
25. An eye for use with a turnbutton fastener according to any one of claims ito 19, the eye comprising a through-hole having a non-circular bore shape and one or more shallow recesses in a surface of the eye, the one or more recesses being alTanged to captively engage an object having a footprint substantially the same size and shape as the through-hole.
26. An eye according to claim 25 wherein the through-hole has a bore shape substantially defined by a regular polygon with rounded-off corners.
27. An eye substantially as herein described with reference to the appended figures.
28. A vehicle wheel comprising an eye according to any one of claims 25 to 27.
29. A vehicle whed according to claim 28 wherein the eye is integrally formed with the hub of the wheel.
30. A vehide having a wheel axle that comprises a turnbutton fastener according to any one of claims 1 to 19 or that compnses a tumbutton fastener including a latch according to any one of dairns 20 to 24.
31. A method of unfastening a tumbutton fastener according to any one of claims ito 19, the method including the step of turning the threaded fastener, wherein turning the threaded fastener is effective to unclamp the latch from the shaft, to engage the latch in frictional contact with the threaded fastener, and to rotate the latch with the threaded fastener from a locked position into an unlocked position.
32. A method of fastening a tumbutton fastener according to any one of claims 1 to 19. the method including the step of turning the threaded fastener, wherein turning the threaded fastener is effective to rotate the latch with the threaded fastener from an unlocked position into a locked posifion, to disengage the latch from frictional contact with the threaded fastener, and to engage the btch directly or indirectly with the shaft to exert a clamping force.
33. A method of fastening or unfastening a turnbutton fastener substantially as herein described.