GB2538251A

GB2538251A - Detachable wheel assembly

Info

Publication number: GB2538251A
Application number: GB1508051.8A
Authority: GB
Inventors: Griffin Robert
Original assignee: TOMCAT SPECIAL NEEDS INNOVATION Ltd
Current assignee: TOMCAT SPECIAL NEEDS INNOVATION Ltd
Priority date: 2015-05-12
Filing date: 2015-05-12
Publication date: 2016-11-16
Also published as: WO2016181158A1; GB201508051D0

Abstract

The assembly 10 comprises vehicle and wheel mountings 12, 14 and a releasable latch 20 for securing them together. A brake force transfer means (43, fig 2) on the vehicle mounting automatically engages a brake actuator (51, fig 2) on the wheel mounting when the mountings are latched together. The wheel mounting may have a body portion 24 and a rotatable hub 26. The brake actuator may include a disc 28 and pads (52, 52, fig 2), the disc being fixed to the rotatable hub and sharing a rotational axis with it. The releasable latch may comprise a locking ring, a lever to release the latch and a pin to prevent its release. The latch ring and cooperating parts of the mounting may have hexagonal profiles that are selectively alignable.

Description

DETACHABLE WHEEL ASSEMBLY

The present invention relates to a detachable wheel assembly, and more particularly to a quick-release detachable wheel assembly to facilitate the rapid removal and replacement of a wheel on a vehicle.

BACKGROUND TO THE INVENTION

Some vehicles, such as wheelchairs, bicycles, mobility scooters, prams, quad bikes and military vehicles, are often transported in a van, car or another vehicle, for example, and can be difficult to load due to their size, weight and shape. This may necessitate removal of the wheels and other parts to reduce the overall size and footprint of the vehicle being transported. Removal of the wheels is also desirable in certain circumstances, to immobilise the vehicle for increasing its security when left unattended.

That said, it may be disproportionately difficult or take a disproportionate amount of time to remove wheels from a vehicle. Often, wheels and wheel assemblies are not designed to be regularly removed, save for servicing and repair. It may involve removing a braking arrangement or a large number of nuts or bolts and can detract from the enjoyment of the intended activity of those concerned.

It is an object of the present invention to reduce or substantially obviate the aforementioned problems.

STATEMENT OF INVENTION

According to a first aspect of the present invention, there is provided a detachable wheel assembly comprising a vehicle mounting, a wheel mounting and a releasable latch for securing the wheel mounting to the vehicle mounting, a brake force transfer means being disposed on the vehicle mounting, and a brake actuator being disposed on the wheel mounting, wherein, when the wheel and vehicle mountings are latched together, the brake force transfer means is automatically engaged with the brake actuator.

The detachable wheel assembly makes it quick and easy to attach a wheel to and detach a wheel from a vehicle. This is particularly useful for partially deconstructing, transporting and reconstructing a vehicle such as a wheelchair or a mobility scooter, for a day out for example. The assembly is envisaged as being used for all the wheels of a vehicle, although it may be limited to a front pair or a rear pair of wheels. The brake system, in particular, is split between the detachable assembly and the vehicle chassis, but acts as a single complete system when the wheel and vehicle mountings are attached to one another. The mountings are securely connected together via the releasable latch.

The wheel mounting may include a body portion, a rotatable hub for mounting a wheel, and a releasable locking device. The locking device may be adapted to automatically lock the hub at a fixed angular position relative to the body portion when the wheel mounting is detached from the vehicle mounting.

This enables the wheel-mounting part to be re-attached to the vehicle-mounting part without independently rotating the body portion of the wheel mounting to align with the vehicle mounting. In particular, when the wheel mounting is detached from the vehicle mounting, the locking device engages and prevents the body portion of the wheel mounting from rotating relative to the hub of its own accord due to gravity, as its centre of mass may lie above the wheel's axis of rotation in use. This stops the body portion re-orienting to have the mass of the body portion hang downwardly, and so the wheel mounting is locked in substantially the correct arrangement needed to re-engage with the vehicle mounting, when it comes to re-attachment. In other words, whilst detached, the wheel mounting components are held in exactly the same arrangement as when they were initially attached, to prevent issues with re-alignment when the mountings are next connected.

The brake force transfer means may include a spring-loaded master brake piston connected to a brake cable. Displacement of the master piston from its default sprung position may be controllable via the brake cable. The brake force transfer means may be hydraulic, in which case the brake cable would be a pipe with hydraulic fluid. Alternatively, the brake force transfer means may be an electric solenoid, pneumatic piston, cable or a cable actuated rod.

The brake actuator may include a spring-loaded slave brake piston, a brake disc, and at least one brake pad. The at least one brake pad may be disposed within the body portion adjacent to a section of the brake disc. The brake actuator may be hydraulic, or one of the alternatives discussed above.

The master and slave brake pistons are spring-loaded to disengage the brakes when braking force is no longer required. In other words, when the user stops pressing the brake pedal, and pressure is no longer transmitted via the brake cable, the master piston returns to a default non-braking position, which simultaneously allows the slave brake piston to return to its default non-braking position, and releases the brake pad(s).

The brake disc may be fixedly mounted to the rotatable hub, and may share a common rotational axis with the hub. This means that the brake disc co-rotates with the hub, and hence the wheel, and so any braking force applied to the disc is thus applied to slowing rotation of the wheel.

The body portion may include a brake disc space. An edge of the brake disc may partially extend into the space when the wheel assembly is assembled. Preferably, there are two brake pads, each disposed on opposite sides of the brake disc.

The slave brake piston may be substantially aligned with and engaged with the master brake piston when the wheel mounting is attached to the vehicle mounting.

When displaced by the master brake piston, the slave brake piston may engage the or each brake pad against the brake disc, exerting a braking force to slow rotation of the brake disc, hub and wheel, in turn slowing the vehicle travelling by virtue of the wheel(s).

The locking device may include a plunger and a spring-loaded locking arm, and the locking arm may control engagement of the plunger with the brake disc. Preferably, the plunger is adapted to automatically engage with the brake disc when the wheel mounting is detached from the vehicle mounting, substantially preventing rotation of the body portion relative to the hub. More preferably, the plunger may be adapted to automatically disengage from the brake disc when the wheel mounting is attached to the vehicle mounting, allowing the hub and wheel to rotate substantially freely relative to the body portion.

The plunger and locking arm advantageously control the orientation of the body portion with respect to the hub when the wheel mounting is detached from the vehicle mounting. This can be achieved by inserting the plunger into one of a plurality of apertures through the external region of the brake disc, preventing rotation of the brake disc and therefore of the body portion relative to the disc, hub and wheel. This can occur automatically as the wheel mounting is detached from the vehicle mounting, substantially preventing any rotation which would cause misalignment of the components in the wheel mounting with those of the vehicle mounting. Consequently, the wheel mounting can be re-attached to the vehicle mounting without needing to manually re-align the body portion first. Additionally, the plunger can disconnect from the brake disc automatically on re-attachment for convenience, mitigating the need to remember to release the plunger prior to using the relevant vehicle.

The releasable latch may include a locking ring to maintain a complementary part of the body portion of the wheel mounting in engagement with the vehicle mounting, a lever for rotating the ring to release the latch, and a locking pin to substantially prevent release of the latch. The locking ring may be spring-loaded to automatically latch the wheel mounting to the vehicle mounting.

The locking ring is advantageous because it substantially prevents the wheel mounting from inadvertently detaching from the vehicle mounting during use. In order to permit detachment, the locking ring must be purposefully rotated via its lever to correctly align for the removal of the wheel mounting. The locking pin prevents the ring being rotated to such a position unless the pin is deliberately removed, preventing accidental disengagement of the locking ring. Using a spring-loaded latch ensures that the latch returns to a locked position by default, being convenient and sewing as a back-up mechanism for substantially maintaining the ring in a misaligned orientation with respect to the body portion of the wheel mounting.

The locking ring may have a substantially non-circular interior, and the complementary part may have a substantially non-circular exterior. The exterior may have a recessed channel inset from an edge of the complementary part to receive the locking ring. The locking ring may bear against the channel when the wheel mounting is attached to the vehicle mounting. The interior of the ring may be shaped to substantially match the exterior of the complementary part in at least one orientation. The interior and exterior sections may have complementary shapes. The interior and exterior sections may be hexagonal.

Using complementary non-circular shapes for the respective interior and exterior sections ensures that at least one orientation of the locking ring will lock the wheel mounting to the vehicle mounting for safety, i.e. when the interior and exterior sections are not rotationally aligned, they cannot slide past one another. This is facilitated by the recessed channel, which seats the ring and allows it to assume a new orientation relative to the exterior section. This in turn causes one or more portions of the ring to bear against one or more sidewalls of the recessed channel, thereby preventing detachment of the wheel mounting from the vehicle mounting. The interior and exterior sections are the same shape and closely matched in size to prevent the ring from sliding over the exterior section in any orientation except the one(s) designed. Using hexagonally shaped sections is a compromise between the number of bearing surfaces when the ring is located within the channel, and the maximum angle through which the ring must pass to move from a completely anti-phase alignment to a position in which it can slide over the exterior section of the complementary part.

The wheel mounting may include an alignment bolt, and the vehicle mounting may include a bolt receiving portion. The bolt may be aligned with the receiving portion when the wheel mounting is correctly oriented for attachment to the vehicle mounting.

The bolt and receiving portion provide a simple and robust means of initially orienting the wheel mounting prior to attaching it to the vehicle mounting. When the bolt is received by the receiving portion (i.e. when the mountings are connected together), it also helps to absorb any transverse shocks (perpendicular to the rotational axis of the wheel) to the mountings during use, which might otherwise damage the connection between the mountings.

The vehicle mounting may include a first axle portion and the wheel mounting may include a second axle portion. Each portion may be adapted to align and interlock with the other to form a complete axle when the wheel and vehicle mountings are attached to one another.

The vehicle mounting may include a drive system, in which the first axle portion may be a master driveshaft controlled by the drive system, and the second axle portion may be a slave driveshaft fixedly mounted to the rotatable hub. The master driveshaft may rotate the slave driveshaft when the master driveshaft is itself driven by the drive system.

This allows the detachable wheel to be a driven wheel (i.e. motorised), rather than a trailing wheel. This is useful where the vehicle is to be driven, as in a quad bike or powered wheelchair, rather than manually pushed or pulled. The drive systems of vehicles are typically complex, and the ability to quickly remove and replace a driven wheel without the need for complete disassembly is highly advantageous; for example, to rapidly repair a broken component of said wheel. The two-part structure of the driveshaft (with respect to a single wheel) is important in this respect, providing a slave portion of the driveshaft which simply attaches and detaches from the master portion of the driveshaft housed within the vehicle mounting, rather than a single piece driveshaft.

The vehicle mounting may include a second body portion and a second releasable locking device. The second locking device may be adapted to automatically lock the first axle portion at a fixed angular position relative to the second body portion when the wheel mounting is detached from the vehicle mounting.

This locks the rotatable axle or driveshaft of the vehicle mounting in position as the wheel mounting is detached. This substantially prevents any rotation which would cause misalignment of the components in the wheel mounting with those of the vehicle mounting, when re-connected. Consequently, the wheel mounting can be re-attached to the vehicle mounting without needing to first manually re-align the driveshaft portions.

The second locking device may include a spring-loaded latch on the second body portion and a collar fixedly mounted to the first axle portion. The collar may have a plurality of notches disposed about its periphery, and each notch may be adapted to receive the spring-loaded latch. Preferably, the spring-loaded latch automatically engages one or more notches in the collar as the wheel mounting is detached from the vehicle mounting, substantially preventing rotation of the first axle portion. More preferably, the spring-loaded latch may automatically disengage from the collar as the wheel mounting is attached to the vehicle mounting, leaving the first axle portion free to rotate. This may be facilitated by the alignment bolt entering the bolt receiving portion.

The latch physically locks the axle or driveshaft in place by engaging a notch (or multiple notches) in the collar. As the collar is integral to the axle or driveshaft, rotation is prevented. As the latch is spring-loaded, it can automatically deploy and latch into the collar as the wheel mounting is detached, avoiding any possibility of further rotation and mitigating the need to manually engage the latch. Furthermore, the latch is adapted to disengage automatically as the wheel mounting is re-attached, mitigating the need to remember to disengage the latch.

Both releasable locking devices may disengage substantially simultaneously when the wheel and vehicle mountings are detached from one another. Similarly, both releasable locking devices may engage substantially simultaneously, when the wheel and vehicle mountings are attached to one another.

This ensures that neither of the axle portions has opportunity to rotate during or after disconnecting the wheel mounting from the vehicle mounting, as the collar (and hence first axle portion) and the brake disc (and hence second axle portion) are both locked at substantially the same time.

According to another aspect of the present invention, there is provided a vehicle including at least one detachable wheel assembly. The or each detachable wheel assembly may include any feature or combination of features described in relation to the first aspect of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, and to show more dearly how it may be carried into effect, reference will now be made by way of example only to the accompanying drawings, in which: Figure 1 shows a perspective view of a first embodiment of a detachable wheel assembly separated into a wheel mounting and a vehicle mounting; Figure 2 shows an exploded perspective view of the detachable wheel assembly of Figure 1; Figure 3 shows a cross-sectional view of the detachable wheel assembly of Figure 1; Figure 4 shows an exploded perspective view of a second embodiment of a detachable wheel assembly; Figure 5 shows a perspective view of a third embodiment of a detachable wheel assembly from one side when assembled; Figure 6 shows a perspective view of the detachable wheel assembly of Figure 5 from the opposite side when assembled; Figure 7 shows a perspective view of the detachable wheel assembly of Figure 5 from one side when disassembled; Figure 8 shows a perspective view of the detachable wheel assembly of Figure 5 from the opposite side when disassembled; Figure 9 shows an exploded perspective view of selected portions of the detachable wheel assembly of Figure 5 from one side; and Figure 10 shows an exploded perspective view of selected portions of the detachable wheel assembly of Figure 5 from the opposite side.

DESCRIPTION OF PREFERRED EMBODIMENTS

Referring firstly to Figures 1 to 3, a first embodiment of a detachable wheel assembly is indicated generally at 10. The assembly 10 is split into a vehicle mounting, indicated generally at 12, and a wheel mounting, indicated generally at 14.

The vehicle mounting 12 includes a first body portion 16, suspension arms 18a, 18b, a releasable latch 20, and a receiving port 22. The first body portion 16 has a female connecting portion 16a in its centre. The suspension arms 18a, 18b form a double wishbone arrangement and are connected about opposing sides of the first body portion 16. One wishbone 18a is mounted about a first hinge pin near the top of the first body portion 16, and the other wishbone 18b is mounted about a second hinge pin near the bottom of the first body portion 16. The wishbones 18a, 18b are further connected to a vehicle chassis (not shown) at their other ends, which may include other suspension components.

The wheel mounting 14 includes a second body portion 24, a rotatable hub 26, a brake disc 28, and a locator pin 30. The rotatable hub 26 is fixedly mounted to the brake disc 28, e.g. bolted through a plurality of holes in each of the hub and disc. The hub 26 and disc 28 share a common rotational axis. A wheel (not shown) is fixedly mounted to the hub 26. The body portion 24 includes a brake actuator (indicated generally at 51) with brake pads 52, 54 disposed either side of a space 32 sized to fit the brake disc 28. The brake disc 28 can extend into and rotate within the space 32 in a conventional manner, when the wheel mounting 14 is attached to the vehicle mounting 12.

The second body portion 24 includes into a male connecting portion 24a, designed to complement the shape of the female connecting portion 16a of the first body portion 16, both being hexagonally shaped. The male connecting portion 24a further includes a recessed channel or groove 24b running around its circumference, offset from the end of the portion 24a. In this embodiment, both connecting portions 16a, 24a have substantially regular hexagonal cross-sections. However, connecting portions with alternative cross-sectional shapes may be provided in alternate embodiments within the scope of the claims. The locator pin 30 is fixed to the body portion 24, being offset from the common rotational axis of the hub 26 and brake disc 28. The locator pin 30 extends away from the second body portion 24 on the opposite side of the brake disc 28 to the hub 26, substantially parallel with the common rotational axis.

The latch 20 includes a locking ring 34 connected to a spring 36, making the latch 20 spring-loaded. The locking ring has a substantially regular hexagonal internal shape to complement the shapes of the male and female connecting portions above. Alternative internal shapes of the ring will be provided to complement the shapes of the connecting portions if their shapes vary in alternate embodiments.

The locking ring 34 further includes a lever 38 disposed on the ring 34 for rotating it, an interlock pin 40 to lock the ring against rotation, and an aperture 42 in the ring to receive the interlock pin 40. A further aperture (not shown) is provided through the body portion 16, for receiving the interlock pin 40. If the interlock pin 40 is engaged through the apertures, the ring 34 cannot be rotated via the lever 38. The male connecting portion 24a is also prevented from exiting the female connecting portion 16a, locking the mountings 12, 14 together for safety until the pin 40 is manually disconnected.

A braking system is provided in the assembly 10, split between the vehicle and wheel mountings 12, 14. The braking system includes brake force transfer means (indicated generally at 43) on the vehicle mounting 12 and the brake actuator 51 on the wheel mounting 14. At one end of the system, the force transfer means 43 includes a brake cable 44 connected to a brake pedal or hand lever (not shown). At the other end of the cable 44 is a plunger 46. The plunger 46 is connected to one end of a lever 48 and is displaceable by applying braking force to the brake pedal or lever. The brake force transfer means 43 controls actuation of the lever 48, and is in turn controlled by the brake pedal or lever.

The lever 48 is hingedly mounted to the first body portion 16, so that it pivots when braking force is applied. The middle of the lever 48 is adjacent to a piston 50. The piston 50 is mounted for displacement through an aperture in the body portion 16. The lever 48 is substantially not in contact with the piston 50 at rest, but does contact the piston 50 when the plunger 46 is displaced and the lever 48 pivots. One end of the piston 50 lies slightly proud of the vehicle mounting 12 to facilitate this, and limit its displacement accordingly. The arrangement shown provides a mechanical link between the lever 48 and piston 50, so that the piston 50 is itself displaced when any substantial force is applied to the brakes. The clearance reduces the risk of someone wearing out the brake pads by 'riding' the brake pedal or lever. The piston 50 includes a return spring 50a, to return the piston 50 to its default position when the brake pedal or hand lever is released.

As previously mentioned, the wheel mounting 14 includes first and second brake pads 52, 54 within the body portion 24. The pads 52, 54 are disposed on either side of the brake disc 28. Magnets 56, 58 are provided outside the respective brake pads 52, 54. Each magnet 56, 58 holds its respective brake pad 52, 54 away from the brake disc 28 when the brakes are disengaged, in conjunction with a steel circlip and backplate (not shown). For example, in this embodiment the magnet 58 is magnetically attracted towards the piston 50, and the other magnet 56 is magnetically attracted in the opposite direction, i.e. both away from the brake disc 28. This prevents wear and chattering of the brake pads 52, 54 against the brake disc 28 when the brakes are not engaged.

The brake actuator 51 includes a first adjustment means 60 and locking nut 60a disposed to the hub side of the brake disc 28, and a second adjustment means 62 and screw portion 62a to the other side of the brake disc 28. The locking nut 60a is provided to secure the first adjustment means 60 in a fixed position. The screw portion 62a can be adjusted to vary the position of the second adjustment means 62 relative to the piston 50.

The vehicle mounting 12 has a first driveshaft portion 63 rotatably mounted within the female connecting portion 16a. The first driveshaft portion 63 is grooved (or splined) at one end, nearest the vehicle mounting 12. The wheel mounting 14 has a second driveshaft portion 64 fixedly mounted through its male connecting portion 24a, the brake disc 28 and the hub 26. The hub 26 is secured to the outermost end of the second driveshaft portion 64 by means of a nut 70. The hub 26 has a set of holes 26a which are used to fixedly engage a wheel (not shown) using bolts or nuts and studs. The hub 26 has a further set of holes 26b which are used to fix the hub to the brake disc using similar means. Thus the hub 26, wheel and brake disc 28 all rotate together in use.

The end of the second driveshaft portion 64 facing the vehicle mounting portion is approximately square in cross-section (as seen in Figure 7 for the third embodiment) to engage a correspondingly-shaped aperture in the first driveshaft portion 63. This allows the driveshaft portions 63, 64 to be securely coupled together, bearing against one another in use to transmit a driving force from an engine and gearbox arrangement (not shown), for example. Alternative shapes may be used, including those where splines are provided to engage corresponding grooves, to maximise the efficiency of power transfer and prevent one portion of the driveshaft slipping relative to the other. The driveshaft portions 63, 64 have bearings 66a, 66b, 66c and spacers 68a, 68b disposed along their length to minimise friction when the portions 63, 64 are rotating. Alternatively, the driveshaft portions 63, 64 may not be driven, merely acting as a free axle for the wheel.

In use, it is a straightforward procedure to mount the wheel mounting 14 and wheel to the vehicle mounting 12. The correct orientation of the wheel mounting 14 with respect to the vehicle mounting 12 is determined by aligning the locator pin 30 with the receiving port 22. When oriented correctly, the male and female connecting portions 24a, 16a also align with each other for mutual engagement in conjunction with the releasable latch 20. The wheel mounting 14 can then be moved towards and engaged with the vehicle mounting 12, allowing the mountings 12, 14 to act together as a complete wheel assembly in use. This functionally connects the brake actuator 51 to the brake force transfer means 43.

The releasable latch 20 is adapted to allow the wheel mounting 14 to be automatically retained by the vehicle mounting 12, when the mountings 12, 14 are engaged in the manner just described. The latch 20 can thereafter be released manually to allow to the wheel mounting 14 to be quickly decoupled from the vehicle mounting 12.

When engaging the wheel mounting 14 with the vehicle mounting 12, the male connecting portion 24a bears against the locking ring 34. When the locking ring 34 is manually rotated to extend the spring 36, the male connecting portion 24a can intrude sufficiently to allow the locking ring 34 to enter the groove 24b. Once the locking ring 34 is no longer borne against by the male connecting portion 24a, releasing the locking ring 34 allows the locking ring 34 to return to its default sprung position. In an alternate embodiment, the locking ring 34 can automatically latch onto the wheel mounting 14, rotating by itself as the male connecting portion 24a bears against it.

The hexagonal internal shape of the locking ring 34 in the groove 24b is purposefully misaligned (or out of phase) with the hexagonal cross-section of the connecting portions 16a, 24a when engaged. Each apex of the internal hexagon of the locking ring 34 is substantially aligned with the centre of an edge of the hexagonal cross-section of the male connecting portion 24a. Jolts or attempted removal of the wheel mounting 14 whilst the locking ring 34 is engaged causes the misaligned hexagonal portion of the connecting portion 24a to bear against the edges of the locking ring 34. Only when the locking ring 34 is rotated via the lever 38 can it align sufficiently with the male connecting portion 24a to exit the groove 24b.

Once attached, the component parts of the braking system on each of the vehicle and wheel mountings 12, 14 operate as a single system. To activate the brakes, the pedal is pressed and braking force is applied to the transfer means 43, which in turn transfers it to the actuator 51. In other words, when braking force is applied, the piston 50 is displaced towards the wheel mounting 14 by the lever 48. The piston 50 in turn applies a force to the screw portion 62a. This causes both brake pads 52, 54 to engage the brake disc 28, thereby slowing rotation of the wheel. As the piston 50 is spring-loaded, it returns to its default position when the braking force is removed, thus releasing the brake pads 52, 54 from the disc 28.

Although the above description considers assembly where the wheel mounting 14 connects to the vehicle mounting 12 via a substantially axial approach, other embodiments are also considered to lie within the scope of the claims. For example, the wheel mounting may connect to the vehicle mounting via a substantially radial approach, i.e. approaching perpendicularly to the rotational axis of the hub, or by a combined radial and axial approach vector.

Referring now to Figure 4, a second embodiment of a detachable wheel assembly is indicated generally at 110. Many of the features of the second embodiment are the same as those of the first embodiment discussed with reference to Figures 1 to 3. Those features that are new in the second embodiment are discussed in detail below, with reference to features that are similar between this embodiment and the first embodiment as needed. Except as described, the embodiment described below otherwise functions in substantially the same way as the first embodiment.

The detachable wheel assembly 110 includes a vehicle mounting and a wheel mounting. The vehicle mounting has a first body portion 112, suspension arms 114a, 114b, and brake force transfer means indicated generally at 116. The wheel mounting includes a second body portion 118, a brake disc 120, a hub 122, and a brake actuator indicated generally at 124. The second body portion 118 has a space 126 into which the brake disc 120 fits when the wheel mounting is assembled. The brake actuator 124 is mounted within the body portion 118 about the space 126.

The braking in this embodiment is hydraulic. The force transfer means 116 includes a brake pipe 119 filled with hydraulic fluid. The brake pipe 119 is connected to a brake pedal or hand lever (not shown) at one end, and to a spring-loaded master piston 128 at the other end. The connection between the piston 128 and the pipe 119 includes a seal 130 to mitigate loss of hydraulic fluid. The piston 128 is mounted through an aperture in the body portion 112.

The brake actuator 124 includes first and second brake pads 132, 134 within the second body portion 118. The pads 132, 134 are disposed on either side of the brake disc 120. First and second gaskets 136, 138 are provided outside the respective brake pads 132, 134 along with first and second slave pistons 140, 142. There is also a third slave piston 144 mounted within the body portion 118 on the side facing the vehicle mounting. The third piston 144 is spring-loaded and has a gasket 146. A screw 148 is provided on the body portion 118 (through a hole or vent in the portion 118) to allow the level of hydraulic fluid to be topped up, whilst substantially preventing leakage of the same fluid when screwed into the body portion 118.

In use, the brake force transfer means 116 activates the brake actuator 124 when braking force is applied to the transfer means 116 via brake pedal or lever is applied. The piston 128 is thus displaced towards the third slave piston 144, which is in turn displaced. The hydraulic fluid transfers the applied force to engage the brake pads 132, 134 with the brake disc 120. The piston 128 can return to its default position when braking force is removed as it is spring-loaded. Furthermore, releasing the braking force removes the applied pressure from the hydraulic fluid, and the brake pads 132, 134 and related pistons return to their default positions, no longer in contact with the brake disc 120.

Referring now to Figures 5 to 10, a third embodiment of a detachable wheel assembly is indicated generally at 210. Many of the features of the third embodiment are the same as those of the first and second embodiments discussed with reference to Figures 1 to 3 and Figure 4. Those features that are new in the third embodiment are discussed in detail below, with reference to features that are similar between this embodiment and the first or second embodiments as needed. Except as described, the embodiment described below otherwise functions in substantially the same way as the first embodiment.

The assembly 210 includes a vehicle mounting and a wheel mounting. The vehicle mounting has a first body portion 212, suspension arms 214a and 214b (not shown), and brake force transfer means (certain components not shown). The vehicle mounting also includes a master driveshaft 213 mounted through the first body portion 212. The master driveshaft 213 has a collar 215 inset from its distal end, on the opposite side of the body portion 212 to that which connects to the wheel mounting. The collar 215 is fixedly mounted to the driveshaft 213. Alternatively the collar 215 may be formed integrally with the driveshaft 213. The collar 215 has a plurality of notches 215a spaced around its circumference. The distal end of the master driveshaft 213 also has splines 213a, to engage with the remainder of the drive system (not shown).

The wheel mounting includes a second body portion 216, a brake disc 218, a hub 220, and a brake actuator (certain components not shown). The wheel mounting also includes a slave driveshaft 221 (see Figure 10) mounted through its body portion 216, aligning with and engaging with the master driveshaft 213 in use. The brake disc 218 has a set of apertures 218a spaced around its periphery. The second body portion 216 has a space 222 into which the brake disc 218 fits when the wheel mounting is assembled. The brake actuator is mounted within the body portion 216 about the space 222.

A first locking device, indicated generally at 224, is mounted to the wheel mounting. The first locking device 224 includes a locking arm 226 and a plunger 228. The arm 226 includes a nub 226a at one end, a central aperture 226b, and a further elongate aperture 226c at its other end; these components are formed integrally. As a whole, the arm 226 is non-linear, with the portion of the arm between the nub 226a and central aperture 226b lying along a different vector to that of the portion of the arm between the central aperture 226b and the elongate aperture 226c.

The arm 226 is pivotally mounted to a bracket 230 on the second body portion 216 via a pin through its central aperture 226b. The plunger 228 has a bracket 228a at one end, and is mounted at that end to the elongate aperture 226c via a further pin, such that pivoting of the arm 226 moves the plunger 228. The other end 228b of the plunger 228 has a reduced diameter, substantially matching the diameter of each of the apertures 218a of the brake disc 218. The arm 226 is spring-loaded (spring not shown), so that its default resting position as mounted to the body portion 216 puts the end 228a of the plunger 228 through one of the apertures 218a in the brake disc 218. The plunger 228 passes through a cylinder 232, as seen in Figure 5. The cylinder 232 has a central aperture or bore substantially matching the diameter of the plunger 228, thus preventing the plunger 228 from approaching the aperture 218a non-perpendicularly. The bore can be lubricated to ensure that the plunger 228 can move within it smoothly. Alternatively, the surfaces of the bore and the cylinder may have low coefficients of friction to mitigate the likelihood of the plunger 228 seizing or sticking within the cylinder 232.

The arm 226 is sprung such that the portion of the arm 226 between the central aperture 226b and the elongate aperture 226c is substantially perpendicular to the axis of rotation of the hub 226 and wheel. Consequently, the portion of the arm 226 between the central aperture 226b and the nub 226a extends outwardly at an angle from the body portion 216. The plunger 228 is engaged with an aperture 218a in the brake disc 218, and thi s prevents the body portion 216 rotating relative to the wheel.

A second locking device, indicated generally at 234, is mounted to the vehicle mounting. The locking device 234 includes a spring-loaded latch 236 (spring mechanism not shown), and operates in conjunction with a bolt 238 on the wheel mounting. The latch 236 includes a rounded nub 236a, a central aperture 236b and a notch-engaging head 236c. The latch 236 is mounted to a bracket 237 on the body portion 212 of the vehicle mounting using a pin 237a.

The head 236c of the latch 236 connects with one of the notches 215a on the collar 215 in the default spring-loaded position of the latch 236, substantially preventing the driveshaft 213 from rotating. The thickness of the latch 236 substantially matches the width of each notch 215a provided on the collar 215 to ensure there is no unintentional rotation of the collar 215 and master driveshaft 213 when the latch 236 is engaged.

The bolt 238 is fixedly mounted to the body portion 216 of the wheel mounting. The bolt 238 has a tapered end 238a, and passes through a bolt receiving portion 240 when the wheel mounting is attached to the vehicle mounting. An aperture 240a is provided in the receiving portion 240 to enable this. The aperture 240a is substantially similar in diameter to the diameter of the bolt, ensuring that the bolt 238 is held securely within the receiving portion, and that it always approaches the nub 236a of the latch 236 at the correct angle.

The rotational symmetry of the ends of the driveshafts 213, 221 governs the angles at which the driveshafts 213, 221 can engage. In this embodiment, the ends of the driveshafts 213, 221 have complementary four-fold rotational symmetry, meaning that the slave driveshaft 221 can notionally engage with the master driveshaft 213 in four possible orientations. A given notch 215a is paired with a given aperture 218a by matching their angular positions on the collar 215 and brake disc 218, ensuring that both locking devices 224, 234 can engage when disengaging the mountings from one another.

It should be noted that certain embodiments may have a greater number of notch/aperture pairs than the rotational symmetry of the driveshaft ends. For example, there may be eight notches and corresponding apertures, with the driveshaft ends having four-fold rotational symmetry. In such an embodiment, whilst there are eight possible orientations in which a given notch could lock to any of the eight apertures, only four of these will allow engagement of the driveshafts 213, 221. The number of notch/aperture pairs, and their angular positions relative to the rotational symmetry of the driveshaft ends, should be taken into account to avoid locking one driveshaft at an angle where it cannot engage the other driveshaft, particularly where the locking devices are engaged manually and may have rotated out of alignment before having been locked in place.

It will be appreciated that any number of notches may be provided in the collar 215. In this embodiment, the notches 215a are equally as numerous as the apertures 218a in the brake disc 218, but the notches may be more or less numerous than the apertures in alternate embodiments. Each notch 215a also preferably lies at the same angular position as one of the apertures 218a when the driveshafts 213, 221 are engaged, so that the locking devices 224, 234 can both engage at a given driveshaft angle.

In use, when attaching the wheel mounting to the vehicle mounting, both the first and second locking devices 224, 234 are in engaged (i.e. locked) states. This means that both driveshafts 213, 221 are locked to prevent rotation before assembly is begun. In other words, the plunger 228 is fully engaged with the aperture 218a in the brake disc 218, and the latch 236 is engaged with a notch 215a on the collar 215, preventing rotation of the driveshafts 213, 221. This may require that one of the driveshafts 213, 221 be released and turned to the relevant position prior to attaching the wheel mounting to the vehicle mounting, either manually or by motorised means.

As the wheel mounting engages the vehicle mounting, the body portion 212 of the vehicle mounting bears against the outstretched nub 226a of the arm 226. This moves the nub 226a towards the body portion 216 of the wheel mounting, against its spring-loaded mechanism. This in turn retracts the plunger 228 out of its aperture 218a in the brake disc 218, releasing the disc 218 for rotation. For the second locking device 234, the bolt 238 must be aligned with the aperture 240a when attaching the wheel mounting to the vehicle mounting. During attachment, the tapered end 238a of the bolt 238 bears against the nub 236a of the spring-loaded latch 236, causing it to rotate about the pin 237a. The angle of the tapered end 238a ensures that a component of the applied force displaces the latch 236 against its spring-loaded mechanism, retracting its head 236c from the collar 215 as the bolt 238 continues to enter the aperture 240a. Thus, both locking devices 224, 234 disengage simultaneously, or almost simultaneously, as part of the connection procedure.

Furthermore, although both locking devices 224, 234 are in the process of being disengaged, the adjacent ends of the master and slave driveshafts 213, 221 interconnect (i.e. engage) prior to either locking device being fully released. Thus, all of the relevant components are unable to rotate until the driveshafts 213, 221 have already re-connected. Once the locking device 234 on the vehicle mounting has been released, the master driveshaft 213 is free to rotate, and hence drive the wheel through its connection with the slave driveshaft 221. The braking system is substantially similar to that described in the first embodiment in structure and in function, although a hydraulic brake system as described for the second embodiment may be used instead.

Having latched the mountings together, the nub 226a is held against the body portion 216 by the other body portion 212. In detaching the wheel mounting from the vehicle mounting (as indicated by arrow A in Figure 7), the spring-loaded mechanism of the arm 226 returns the arm 226 to its default position, moving the plunger 228 (as indicated by arrow B in Figure 7) towards and into one of the apertures 218a in the brake disc 218. There are seven apertures in the embodiment shown, but it will be appreciated that any number of apertures may be provided at the relevant radius from the centre of the brake disc 218 to meet the plunger 228.

Furthermore, disengaging the mountings (as indicated by arrow C in Figure 8) causes the bolt 238 to be withdrawn at the same time as the arm 226 returns to its default position, gradually ceasing to bear against the latch 236. The spring-loaded mechanism of the latch 236 therefore returns the latch 236 to its default position as the tapered end 238a of the bolt moves away from the nub 236a. Consequently, the head 236c of the latch 236 moves towards and engages one of the notches 215a of the collar 215 (as indicated by arrow D in Figure 8). There are seven notches in the embodiment shown, but it will be appreciated that any number of notches may be provided as previously discussed.

Other embodiments are also considered to lie within the scope of the claims. The detachable wheel assembly is suitable for use with all kinds of wheels, including bicycle wheels, car wheels and wheelchair wheels, amongst others. The braking system may be electronically or pneumatically operated, rather than a direct hydraulic or mechanical system. Other components such as mud guards and a drive system may be provided.

For example, the drive system may be incorporated into the wheel mounting, for independently driving the wheel, being detachable with the wheel mounting. Other arrangements or types of locking devices not described herein may be used to maintain mutually compatible rotational arrangements of each mounting, within the scope of the claims.

The embodiments described above are provided by way of example only, and various changes and modifications will be apparent to persons skilled in the art without departing from the scope of the present invention as defined by the appended claims.

Claims

CLAIMS 1.
2.
3.
4.
5.
6.A detachable wheel assembly comprising a vehicle mounting, a wheel mounting and a releasable latch for securing the wheel mounting to the vehicle mounting, a brake force transfer means being disposed on the vehicle mounting, and a brake actuator being disposed on the wheel mounting, wherein, when the wheel and vehicle mountings are latched together, the brake force transfer means is automatically engaged with the brake actuator.

A detachable wheel assembly as claimed in claim 1, in which the wheel mounting includes a body portion, a rotatable hub for mounting a wheel, and a releasable locking device, the locking device being adapted to automatically lock the hub at a fixed angular position relative to the body portion when the wheel mounting is detached from the vehicle mounting.

A detachable wheel assembly as claimed in claim 1 or 2, in which the brake force transfer means includes a spring-loaded master brake piston connected to a brake cable, where displacement of the master piston from its default sprung position is controllable by pressure transmitted through the brake cable.

A detachable wheel assembly as claimed in any of claims 1 to 3, in which the brake actuator includes a spring-loaded slave brake piston, a brake disc, and at least one brake pad, the at least one brake pad being disposed within the body portion adjacent to a section of the brake disc.

A detachable wheel assembly as claimed in claim 4, in which the brake disc is fixedly mounted to the rotatable hub, sharing a common rotational axis with the hub.

A detachable wheel assembly as claimed in claim 4 or 5, when dependent on claim 2, in which the body portion includes a brake disc space, an edge of the brake disc partially extending into the space when the wheel assembly is assembled.
7. A detachable wheel assembly as claimed in any of claims 4 to 6, in which there are two brake pads, each being disposed on opposite sides of the brake disc.
8. A detachable wheel assembly as claimed in any of claims 4 to 7, in which the slave brake piston is substantially aligned and engaged with the master brake piston when the wheel mounting is engaged with the vehicle mounting.
9. A detachable wheel assembly as claimed any of claims 4 to 8, in which the slave brake piston, when displaced by the master brake piston, engages the or each brake pad with the brake disc, exerting a braking force to slow rotation of the brake disc and hub.
10. A detachable wheel assembly as claimed in any of claims 4 to 9, when dependent on claim 2, in which the locking device includes a plunger and a spring-loaded locking arm, the locking arm controlling engagement of the plunger with the brake disc.
11. A detachable wheel assembly as claimed in claim 10, in which the plunger automatically engages with the brake disc as the wheel mounting is detached from the vehicle mounting, substantially preventing rotation of the body portion relative to the hub.
12. A detachable wheel assembly as claimed in claim 10 or 11, in which the plunger automatically disengages from the brake disc as the wheel mounting is attached to the vehicle mounting, allowing the hub to rotate substantially freely relative to the body portion.
13. A detachable wheel assembly as claimed in any preceding claim, in which the releasable latch includes a locking ring to engage and retain a complementary part of the body portion of the wheel mounting with the vehicle mounting, a lever for rotating the ring to release the latch, and a locking pin to substantially prevent release of the latch.
14. A detachable wheel assembly as claimed in claim 13, in which the locking ring is spring-loaded to automatically latch the wheel mounting to the vehicle mounting.
15. A detachable wheel assembly as claimed in claim 13 or 14, in which the locking ring has a substantially non-circular interior, and the complementary part has a substantially non-circular exterior.
16. A detachable wheel assembly as claimed in claim 15, in which the exterior has a recessed channel inset from an edge of the complementary part to receive the locking ring, the locking ring bearing against the channel when the wheel mounting is attached to the vehicle mounting.
17. A detachable wheel assembly as claimed in claim 15 or 16, in which the interior of the ring is shaped to substantially match the exterior of the complementary part in at least one orientation.
18. A detachable wheel assembly as claimed in any preceding claim, in which the wheel mounting includes an alignment bolt, and the vehicle mounting includes a bolt receiving portion, the bolt being aligned with the receiving portion when the wheel mounting is correctly oriented for attachment to the vehicle mounting.
19 A detachable wheel assembly as claimed in any preceding claim, in which the vehicle mounting includes a first axle portion and the wheel mounting includes a second axle portion, each portion being adapted to align and interlock with the other to form a complete axle when the wheel and vehicle mountings are connected.
20. A detachable wheel assembly as claimed in claim 19, in which the vehicle mounting includes a drive system, the first axle portion being a master driveshaft controlled by the drive system, and the second axle portion being a slave driveshaft fixedly mounted to the rotatable hub, where the master driveshaft rotates the slave driveshaft when itself driven by the drive system.
21. A detachable wheel assembly as claimed in claim 19 or 20, in which the vehicle mounting includes a second body portion, and a second releasable locking device, the second locking device being adapted to automatically lock the first axle portion at a fixed angular position relative to the second body portion when the wheel mounting is detached from the vehicle mounting.
22. A detachable wheel assembly as claimed in claim 21, in which the second locking device includes a spring-loaded latch on the second body portion and a collar fixedly mounted to the first axle portion, the collar having a plurality of notches disposed about its periphery, each notch being adapted to receive the spring-loaded latch.
23. A detachable wheel assembly as claimed in claim 22, in which the spring-loaded latch automatically engages one or more notches in the collar as the wheel mounting is detached from the vehicle mounting, substantially preventing rotation of the first axle portion.
24. A detachable wheel assembly as claimed in claim 22 or 23, in which the spring-loaded latch automatically disengages from the collar as the wheel mounting is attached to the vehicle mounting, leaving the first axle portion free to rotate.
25. A detachable wheel assembly as claimed in any of claims 21 to 24, when dependent on claim 2, in which both releasable locking devices disengage substantially simultaneously when the wheel and vehicle mountings are detached from one another.
26. A detachable wheel assembly as claimed in any of claims 19 to 23, when dependent on claim 2, in which both releasable locking devices engage substantially simultaneously when the wheel and vehicle mountings are attached to one another.
27. A vehicle including at least one detachable wheel assembly as claimed in any preceding claim.
28. A detachable wheel assembly substantially as described herein, with reference to and as illustrated in Figures 1 to 10 of the accompanying drawings.