TITLE
WHEELS AND TYRES FOR WATER-BORNE CRAFT FIELD OF THE INVENTION This invention concerns transportation. More particularly, it concerns wheel structures and tyres which provide both flotation and means to propel a vehicle that is adapted to be driven on water (and sometimes also on land). BACKGROUND ART
Various forms of amphibious craft have been known for some time. These incl'αde vehicles having both wheels for driving on land and a motor-driven propeller for propulsion when the vehicle is travelling over water. In addition, there are non- amphibious craft of various kinds which use floats for support in water and paddles for propulsion.
The present invention concerns wheels which are adapted both to support a vehicle (that is, to provide flotation) and to provide a means for propelling a vehicle over water (and sometimes also over land). DISCLOSURE OF THE INVENTION
It is an objective of the present invention to provide new forms of wheel and tyre construction which will provide efficient propulsion of water-borne craft over or through the water. Another objective of the present invention is to enable the physical dimensions of water craft to be reduced,
thus permitting easier transportation of the craft over land when such transportation is necessary.
These objectives are achieved by three improvements, two of which may be adopted separately or simultaneously. In discussing these improvements, reference will be made to water tricycles, for the production of a new form of water tricycle was a catalyst in the conception of the present invention. It will be appreciated, however, that the basic forms of the present invention are not limited to water-borne craft which resemble tricycles. The first improvement is the fabrication of an inflatable tyre out of a flexible rubber or like compound, which is adapted to fit over a simple rim, the tyre having formed therein or bonded thereto a plurality of protrusions, which extend across the outermost part of the side regions of the tyre. Such a tyre can be readily deflated for removal from the rim to facilitate transport of the water vehicle such as a water tricycle, while the extensions of the protrusions around the tyre provide additional "driving fin area" as the water craft's wheels sink further into the water with a heavier rider of the water craft.
Thus, according to one aspect of the present invention, a tyre for use on a recreational craft that is adapted to float on water comprises: (a) an inflatable toroidal structure, of substantially elliptical cross-sectional shape when inflated, constructed of a flexible, resilient sheet material; and
(b) a plurality of fin-like protrusions from the general toroidal surface, in spaced apart location around the toroid, each protrusion being formed in or bonded on to the structure and extending substantially transversely over the region of the surface thereof that constitutes the outermost surface of the toroid and terminating in the regions of the surface of the structure that constitute the generally opposed side surfaces of the toroid.
Typically, the material of the tyre is a synthetic rubber compound or sheet neoprene. It will also be appreciated that an ellipse includes within its definition a circle and, in the context of this specification, oval shapes of any suitable major or minor axis ratio.
The second improvement is the provision of a wheel structure comprising:
(a) a hub having a first plurality of radial slots f-ormed therein; and
(b) a first plurality of spokes adapted to be fitted into said slots, said spokes being generally lamellar and having their outermost regions shaped to encircle part of a tyre adapted to be fitted to the wheel structure.
The spokes of the hub may be constructed of any suitable material, but a plastics material or a reinforced fibreglass material is preferred as such materials are strong and light-weight and do not corrode or chemically decompose in water or in a high humidity environment.
The spokes may be flat or curved. They will usually be equi-spaced around the hub. The thi.rd improvement, aimed solely at increasing the efficiency of operation of the water craft, is the formation of a moulded wheel, having a hub region and tyre region, as a single unit, from a substantially rigid material, with fins formed integrally with the tyre region, the fins being formed on at least one side of the tyre region and extending towards the hub xegion- With this form of substantially rigid construction, the proportion of the fin surface area which becomes submerged when the water craft is "driven" by rotation of the wheel depends on the weight being carried by the
water craft. Thus a heavier user of the water craft has a greater fin area for propulsion of the vehicle than a light-weight user of water craft equipped with this type of wheel. The present invention also includes, within its scope, a water tricycle or similar recreational water craft constructed to include tyres and/or wheel structures of the type defined above. Embodiments, of the present invention will now be described, by way of example, together with a preferred water tricycle constructed, with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a general side view, partly detailed, of a tyre constructed in accordance with the first aspect of the invention.
Figure 2 is a schematic cross-sectional view of a tyre of the type shown in Figure 1, mounted on a central wheel structure of a water tricycle or similar recreational craft.
Figure 3 is a schematic front view of a tyre of the first aspect of the present invention.
Figure 4 is a schematic side view of a hub of a wheel structure of the second aspect of the present invention.
Figure 5 is a section AA of Figure 1; Figure 6 illustrates one form of spoke of the wheel structure of the second aspect of the present invention.
Figure 7 is a view similar to that of Figure 5, with spokes and a tyre fitted
to the hub of Figure 4.
Figure 8 illustrates how non-planar spokes can be fitted to a hub to form the wheel structure of the present invention. Figure 9 shows how the wheel structure of the second aspect of the present invention may be used with the inflatable tyre of the first aspect of the present invention.
Figure 10 is a schematic side view of a water tricycle incorporating the first aspect of the present invention.
Figure 11 is a perspective sketch of one form of wheel constructed in accordance with the third aspect of the present invention. DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENT To assist in the understanding of the first aspect of the present invention, it should be noted that the following terms have
been given the meaning that is now indicated:-
(a) outer tyre surface:- that is the annular region of the surface of the tyre contained between the points A and B shown in Figure 2;
(b) side surfaces of the tyre:- these are the annular surfaces contained between points B and C and between points A and D of the tyre illustrated in Figure 2, and indicated as dashed lines A and D in Figure 1; and
(c) inner surface of the tyre:- that is the inner surface contained between the points C and D of the tyre shown in Figure 2.
Referring now to Figures 1, 2 and 3, there is shown a toroidal structure 10 which has been inflated (in Figure 2, after it has first been located around the curved rim 12 of a wheel section 11 of a water tricycle or like recreational vehicle). As indicated earlier in this specification, the structure 10 is constructed of a flexible, resilient sheet material, such as a synthetic rubber material or neoprene. On the outer tyre surface, a plurality of fin-like protrusions or ribs 13 are located. These protrusions or ribs 13 may be moulded in the material of the toroidal structure 10, so that they stand out therefrom when the tyre is inflated. Alternatively, as indicated above, the ribs 13 may be bonded to the toroidal structure 10 by any suitable adhesive or by a vulcanizing process.
As shown particularly in Figures 1 and 3, the ribs or protrusions 13 extend transversely of the outer surface of the tyre and are continued over the side surfaces of the tyre. This feature ensures that when an adult is using a water tricycle fitted with a tyre constructed in accordance with the present invention, as the tyre sinks further into the water (compared to the situation when a child rides the water tricycle) the surface area of the submerged parts of the ribs 13 increases. Thus the adult is provided with larger "paddles" on the driving wheels of the water tricycle than a child, and the adult obtains correspondingly better propulsion with one rotation of the wheel. Hence the present invention will provide a more uniform efficiency of operation of the tricycle or similar craft when light and heavy riders use it.
For convenience, the inflation nozzles for the tyres have been omitted from the drawings, but those familiar with tyre constructions will recognise that the fitting of inflation nozzles is a standard practice and requires no novel skills.
Figure 3 shows that it is not essential for the ribs or protrusions 13 to extend linearly over the outer surface of the tyre. The ribs or protrusions 13 may be curved, or have a zig-zag, sine curve, or any required "tread" pattern as they traverse the outer surface of the tyre.
Figure 2 shows that this form of tyre may be used with a simple wheel structure for a water tricycle. The wheel structure 11 of Figure 2 may be conveniently moulded out of a rigid plastics material, or may be of fibreglass. If required, a band 15 of a suitable material may be positioned around the rim 12 to separate the inner surface of the tyre from rim 12. The wheel structures 11 could be made of metal, but metal wheel structures are not preferred because they are usually heavier than plastic constructions and are more prone to corrosion in a watery environment. Referring now to Figure 4, a hub 40 is constructed with a central aperture 41, adapted to be fitted to an axle (not shown). The hub 40 has a plurality of slots 42 extending radially to the outer periphery of the hub, on each side of the hub. As shown clearly in Figures 4 and 5, the slots 42 preferably extend across the outer peripheral edge surface 43 of the hub, which, as shown in Figure 5, may be a concave surface.
Spokes 44 are adapted to be fitted to the hub- 40 by locating them within the slots 42 and securing them in the slots by any suitable means, including by a press-fit or drive-fit arrangement. As shown in Figures 6 and 1 , the spokes 44 are shaped so that the portion of a spoke mounted on a hub which is not surrounded by a slot 42 (that is, the portion of the spoke which lies outside the
dashed line 45 shown in Figure 6) acts as a paddle when the hub is rotated. The outer surface 46 of the illustrated spokes is shaped to provide a recess, so that a tyre - for example, an inflatable rubber tyre - may be supported within the recess.
If a wheel should be constructed using spokes of the type illustrated in Figure 6, the tyre would be supported by the spokes to be clear of the hub 40. Preferably, however, the spokes 44 and the slots 42 will be so dimensioned that the innermost part of the outer surface 46 of each spoke lies within, or is at the edge of, a slot 42- in the hub 40. With this preferred arrangement, the tyre of the wheel will be in contact with the hub 40 at surface 43, and this contact, with the support provided by the spokes of the wheel, results in a very stable wheel being produced for, for example, a water tricycle.
The spokes 44 have already been shown to be of lamellar construction. However, the spokes need not be planar, but may be curved, and mounted on a hub as shown schematically in Figure 8.
It will be appreciated that any suitable number of spokes may be fitted to a hub. Clearly, if the spokes have a configuration similar to that shown in Figure 6, they will need to be more numerous than if the spokes have the configuration illustrated in Figure 7, to properly support a tyre on the wheel structure formed by the hub and the spokes.
As shown in Figure 9, the wheel structure of the present invention can, with advantage, be used with the ribbed tyre structure of the first aspect of the present invention, described above, for the ribs 48 on the tyre 49 provide a surface upon which the spokes of the present wheel structure can bear, thus ensuring that the tyre 49 moves with the spokes and hub when the entire wheel assembly is rotated.
Varations of the wheel structure of the second aspect of the present invention are, of course, possible, without departing from the present inventive concept. For example, the slots 42 may extend to the central aperture 41. Also, the slots 41 may be radially tapered, so that they become shallower as they approach the centre of the hub 40. The simple water tricycle illustrated in Figure 10 has a main frame comprising a single tubular frame 20, on which is mounted a seat 21 and a handlebar/fork assembly 22. The front wheel 23 of the water tricycle preferably has an inflatable tyre on it, without the ribs or protrusions 13 of the tyre of the first aspect of the present invention. The two "driving" wheels 24 of the water tricycle are constructed to incorporate tyres in accordance with the first aspect of the present invention, and preferably comprise a structure of the type illustrated in Figure 9. These driving wheels are driven by a conventional pedal and chain arrangement 25.
Such a water tricycle is easy to use, robust, and easily transported.
A wheel constructed in accordance with the third aspect of the present invention as illustrated in Figure 11. Figure 11 is a sketch of one form of moulded fibreglass wheel that has been constructed by the present inventors and effectively used in water tricycles. The wheel of Figure 11 consists of two half-wheel units 50, 50A, which are moulded separately and brought together and joined by any suitable means at the rim 55 of the wheel. The wheel itself has a tyre region 51 and a hub region 52. The hub region 52 is adapted to be fitted to an axle at aperture 54. The tyre region 51, which is used to provide buoyancy for the water craft, carries fins 53 which are used to propel the water craft through and over water when the wheel is rotated.
It will be clear that the extent to which the fins 53 at the lower part of the wheel of Figure 11 are submerged when the wheel is used in a water craft must depend on the weight that is being supported by the wheel. Consequently, the fins of a water craft that is being used by a child will not be submerged to the same extent as the fins of the same water craft that is being used by an adult.
Although fibreglass construction of the wheel of Figure 11 has been referred to above, any suitable, substantially rigid,
material may be used. A particular advantage of this type of structure is that the water craft using this type of wheel construction can be truly amphibious. The user may even wear a suit to ride a water tricycle fitted with this type of wheel from a sandy beach into a lake or sheltered harbour without the user getting his clothes wet.
Other shapes of fin 53 may be used, instead of the illustrated shape, without departing from the inventive concept of this aspect of the present invention. Also, if required, the fins 53 may be formed in both sides, of the tyre region of the wheel. INDUSTRIAL APPLICABILITY
The main use of the present invention is in the production of pleasure craft for use on inland lakes, large swimming pools, harbours, bays, and similar environments.