Amphibious vehicles

Abstract

An amphibious vehicle comprising a body, at least one rotor carried by the body for contributing to the support and for propelling the vehicle over land and water, and drive element for rotating the rotor, the rotor including a pair of laterally spaced end members, restraining element located between the end members adjacent to the periphery of the end members, a fluid impermeable flexible membrane extending between the end members, and an element for securing the membrane to the end members in fluid-tight relation thereto, the membrane between the end members being secured to the restraining element at circumferentially spaced locations, whereby the membrane is radially deformable between the locations, device for internally pressurizing the membrane to a pressure such that portions of the membrane between the locations when in contact with water will present a concave driving surface, a centrally located buoyancy chamber within the rotor, and wherein each end member has a peripheral surface for land travel.

Parent Case Text

This application is a continuation of applicants co-pending now abandoned application U.S. Ser. No. 240,351 filed April 3, 1972 entitled AMPHIBIOUS VEHICLES.

Description

This invention relates generally to amphibious vehicles of the type which are propelled through water or over land by rotors. More specifically, the invention relates to the rotors themselves.

In a preferred embodiment, the rotors are also designed to provide the total or major buoyancy of the vehicle. Preferably, therefore, when the vehicle is in water, the payload is supported totally clear of the water. It is envisaged, however, that the rotors could be used on a vehicle in which the payload is only partly clear of the water surface or is even submerged. In many respects, the preferred embodiment of amphibious vehicle of the present invention bears similarities to an air cushion vehicle and in fact, in one embodiment, it is envisaged that the buoyancy of the vehicle may be assisted by means of an air cushion.

The inventive vehicle has all the advantages of an air cushion vehicle namely, the ability to travel on land or water, with the result tht no expensive docking facilities are required, and maintenance is simple, the vehicle can operate regardless of the state of the tide, water depth and natural obstructions, drive on/drive off loading is possible, and turnaround is rapid. One of the disadvantages of air cushion vehicles, however, is their noise in operation, due largely to the air propellers necessary to propel the vehicle, and another disadvantage is the spray or dust thrown up by the air escaping from beneath the skirt of the vehicle. The present invention, however, seeks at least partially to overcome these problems. This is partly achieved by reducing water-wetting drag on the vehicle by reducing the relative velocity of the craft surface and the water through which it is moving.

According to the broadest aspect of the present invention, I provide a rotor for an amphibious vehicle, comprising a pair of horizontally spaced end members provided with a peripheral surface for land travel, a plurality of peripheral tie members extending at spaced peripheral points around said end members, between said end members, and a fluid impermeable membrane extending in fluid tight manner between the peripheries of said end members, whereby, when said outer membrane is subjected to an internal fluid pressure, the configuration of said membrane will be controlled, and drive means for rotating said rotor.

Preferably, the rotor is mounted on a central shaft which preferably is driven by the drive means.

Preferably, a buoyancy chamber is provided within the rotor, and surrounding the central shaft. Preferably, the buoyancy chamber comprises an inflatable member of annular cross section.

Preferably, the shaft is hollow and one or more passages extend from the inside of the hollow shaft to the space defined by said outer membrane. The drive means may comprise a hydraulic motor which may be located axially within one of the end members.

Preferably, each end member is a disc and is comprised of an inner and outer annular plate spaced apart and stiffened by a plurality of radially disposed diaphragm plates, the diaphragm plates and plates being connected to a circumferential rim plate and being connected at their radially innermost ends to a suitable circular plate which defines a housing for a hydraulic wheel motor. There are thus formed a plurality of hollow segment-like cavities which preferably are filled with a low density filler.

Because the end discs are mounted on a common shaft, their peripheries are connected together by the tie members, and they are spaced apart by the pressurised chamber, drive from the hydraulic motor mounted in one of the end discs is transferred right across the rotor without there being noticeable relative rotation between the end discs.

Preferably, end portions of the outer membrane are sandwiched between the circumferential plate of each end disc and a mild steel rim plate, the said rim plate being connectible to the circumferential plate by means of nuts and bolts. Preferbly, a tread is mounted in said rim plate to provide said peripheral surface, the tread permitting a vehicle to which the rotor is fitted to be used on dry land.

The outer membrane may be formed around its periphery with pockets, the circumferential spacing of which corresponds with that of the tie members, in which pockets the tie members are located, for radially confining the membrane.

Preferably, internal sleeves are provided within said pockets to reduce wear between the tie members and the pockets.

According to a further feature of the present invention, I provide an amphibious vehicle provided at each of its ends with a rotor as described above. Preferably the vehicle is generally rectangular in plan and is provided with four such rotors, one at each corner, said rotors being located beneath an upper housing and supported upon a main frame of the vehicle.

Preferably, the two rotors at each end of the vehicle are mounted in axial alignment, and a common dry bearing supports the inner ends of the shafts, the dry bearing being carried by the frame of the vehicle and being constructed to allow passage of air to the interior of the shafts.

Preferably, the air within each rotor is supplied by a fan on the vehicle driven by an internal combustion engine.

Preferably, a hydrofoil is associated with each rotor, the hydrofoil being located on that side of the rotor which is downstream when the vehicle is moving in a forward direction, the angle of incidence of the hydrofoils preferably being adjustable. Preferably the hydrofoils are retractable.

A preferred embodiment of the present invention is now described with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view, with parts broken away, and parts in section, of one particular embodiment of amphibious vehicle,

FIG. 2 is a section of an end disc of one of the rotors shown in the vehicle of FIG. 1,

FIG. 3 is a detail of the section shown in FIG. 2,

FIG. 4 is a further section of the end disc, showing the method of connection of a tie member to the end disc, and a membrane and tread fixed in position,

FIG. 5 is a section on the line V--V of FIG. 4, and

FIG. 6 is a schematic sectional view through a rotor and its associated hydrofoil.

Referring to the drawings, the amphibious vehicle is indicated generally at 1 and has a main frame constructed for example of aluminium alloy sections 3 on which is supported a passenger compartment indicated generally at 5. The vehicle is powered by a conventional internal combustion engine 7 which drives a hydraulic pump 9 and a compressor 11. All the expected fittings are provided in the passenger compartment 5 and there is no need for these to be described in detail.

A pair of front rotors, 13, 15 is supported by the frame 3 at its front end and a pair of rear rotors 17, 19 is supported on the frame adjacent its rear end. A front hydrofoil 21 is supported from the frame 3 immediately to the rear of the front rotors 13 and 15 and an aft hydrofoil 23 is likewise supported at the rear end of the frame immediately behind the rear rotors 17 and 19. Suitable incidence control jacks 22 and 24 control the pitch of the hydrofoils 21 and 23 respectively, and the hydrofoils are retractable by linkages 25 and 27 respectively under the control of retraction jacks 29 and 31 respectively.

The floor of the passenger compartment 5 is made of buoyant materials, and as shown comprises polystyrene foam 26 sandwiched between two wooden ply layers 28 and 30. To protect the craft from damage, a rubber bumper 33 is secured to the side members of frame 3.

Each of the rotors 13, 15, 17 and 19 is substantially identical and accordingly, only one will be described in detail. The rotors, in the preferred embodiment, give the vehicle its total buoyancy and provide its sole means of travel, whether on land, sea or swamp land. The front rotors 13 and 15 are mounted on hollow shafts 35 supported at one end in a common dry bearing 37, the rotors being arranged one on each side of the bearing 37. At the other end of each hollow shaft 35, a hydraulic motor 38 provides a journal for the shaft, the motor itself being supported in suitable manner on the frame 3.

Each rotor is comprised of a pair of end discs 39, 41, the discs 39 and 41 being fixed for rotation with the shaft 35 either by welding or by splining, for example, and the disc 41 has a central aperture 43 (see FIG. 2) for the motor 38 and is connected to the shaft 35 by a plate 45 closing off the inner end of the aperture 43. The general cross section of the discs is apparent from FIG. 2 and these are constructed from a plurality of radially dispersed diaphragm plates 47 of a trapezoidal shape, their non-parallel sides being connected to inner and outer disc shaped plates 49 and 51 respectively, the former having a peripheral flange 50 abutting the latter. The spaces between adjacent diaphragm plates 47 are filled with a low density filler such as polystyrene granules in an epoxy matrix, thereby imparting buoyancy to the end discs.

A plurality of parallel circumferentially spaced tie members 53 extend between the end discs of each rotor, each of the tie members being parallel to the shaft 35. The tie members may for example be made of half-inch hollow Dural tube, or metal or plastics sections or they could even be in the form of wire ropes but they must be capable of withstanding considerable forces at right angles to their longitudinal axis, as well as considerable tensile force.

Within each rotor, a buoyancy chamber 55, as shown, for high pressure gas, preferably air, surrounds the shaft 35, and as shown, this pressure chamber 55 is provided by an inflatable inner bag 57 of annular cross section. The fluid pressure (e.g. of air or other gas) within the bag should be constant, but could be controlled from a control console within the passenger compartment through an air line communicating with the chamber 55 and the compressor 11 via the shaft 35 and a hollow duct 59 supporting the bearing 37.

A flexible outer membrane 61 extends peripherally around each rotor, the ends of the membrane 61 being connected to the end discs preferably in the manner shown in FIG. 3. The membrane 61 is made of an air impermeable wear-resistant material such as nylon, rubber or PVC suitably reinforced if necessary (such as that used in the "skirt" of commercial air cushion vehicles) and in a preferred arrangement (see FIGS. 4 and 5), a plurality of pockets 40 peripherally spaced around the membrane 61, and extending between opposite ends of the membrane, are provided, the spacing of the pockets corresponding with that of the tie members 53. These pockets 40 are lined with a wear-resistant sleeve-like member 42 and the tie members 53 are then located within the lined pockets 40 so that the membrane 61 is confined to the general shape of the rotor by means of the tie members 53.

The outer periphery of each end disc 39, 41 is preferably strengthened by an annular plate 63 of L-shaped cross section, welded to the disc-like plates 49 and 51 and overlying the flange 50. The plate 63 and the flange 50 are apertured at circumferentially spaced intervals to enable a tread or tire for overland travel to be fitted to the periphery of the disc. The edge portion of the membrane 61 is folded upon itself as shown at 65 and is then located over the annular plate 63 and is then sandwiched between the plate 63 and an annular rim plate 67 provided with a radially disposed flange 69 and on which is mounted a solid tread 71. Suitable nuts and bolts secure the tread 71 and plate 67 to the plate 63 on the periphery of the end disc, at the same time securely holding the membrane 61 in position. If desired, the solid rubber tread 71 may be replaced by a pneumatic tire (not shown).

For the purpose of connecting the tie members 53 to the end discs 41, the latter are provided with a plurality of circumferentially spaced passages 44 in each of which is located an inwardly directed flange 46 (see FIG. 4). The end of each tie rod 53 is formed with an internal screw thread 48 and is located within the respective pasage 44, against the flange 46 and held in position by an Allen screw 50, which also seats against flange 46. The outer end of each passage 44 is blanked off with a grub screw 52, a spacer 54 being located between the grub screw 52 and the Allen screw 50. The tie rods 53 can thus be withdrawn through the passages 44 when required.

The space between the outer membrane 61 and the radially outermost wall of the inner bag 57 is in communication with the compressor 11 via a radial passageway 73, the hollow shaft 35 and the duct 59, and the pressure of air in the chamber 75 formed by the membrane 61 and outer wall of the inner bag 57 is controllable from the driver's console within the passenger compartment 5. It will be appreciated that the inner bag, when inflated, improves the torsion transmitting characteristics of the rotor, gives the rotor buoyancy, and also reduces the volume of the chamber 75, thereby making the control of pressure within the chamber easier.

Each portion of outer membrane 61 between any two adjacent tie members 53 will hereinafter be referred to as a rotor blade. It will be appreciated that the surface shape of the rotor blades will be controlled by the pressure of air in the chamber 75. For example, if the pressure is slightly greater than atmospheric, those blades presented to the atmosphere will take up a convex shape when viewed from outside. On the other hand, if the vessel is floating in water, it is probable that those blades in contact with the water will take up varying concave shapes, depending upon the relationship between the pressure in the chamber 75 and the weight of the vehicle, the speed of rotation of the rotor and the precise location of the blade. Because the shape of the rotor blades beneath the water can be finely controlled by altering the pressure of air within the chamber 75, the propulsion characteristics of a rotor which is being rotated by the hydraulic motor can be chosen for optimum performance. Furthermore, characteristics of the blades can be altered by different tailoring of the membrane 61. Because of the shape of each blade beneath the water, the rotors can be used as the sole means of propulsion for the vehicle as well as giving the vehicle the necessary buoyancy. Also, the rotors can be used to alter the stiffness and damping of the vehicle's suspension. It will be appreciated however, that buoyancy could be assisted or totally provided in other ways. For example, the vessel could have a displacement hull and float like a traditional boat and it is even envisaged that an air cushion could be used for buoyancy purposes. If an air cushion is used, buoyancy hulls could be provided along each side of the vessel, and these, together with the rotors, could perform the task of confining the air cushion, in place of the more conventional flexible skirt. Alternatively, hydrofoils could be used for this purpose.

In fact, if the water over which the rotor is rolling were unyielding, the action of the rotor would be analogous to that of a pinion on a rack and the advance per revolution would be equal to the circumference of the pitch circle of the blades of the rotor. The water does however yield to the pressure of the blades and the amount by which the actual advance differs from the circumference of the pitch circle per unit time is known as slip and is a measure of the state of operation of the rotor. The torque or couple resisting rotation, experienced by the rotor gives a horizontal thrust components in a direction parallel to the plane of rotation of the rotor. This thrust component and torque are functions of the rotor speed of rotation, forward speed and diameter.

The displacement of water by the rotors gives a bouyant lifting force. The distribution of pressure on the rotor by hydrostatic forces when the rotor is at rest is augmented by hydro-dynamic forces when the rotor is in motion. The presence of the blades on the rotor and the rotor motion control this pressure distribution. The net upthrust, or lift on the rotor system, will vary with the rotational speed.

The lift and thrust components on each rotor can be controlled, independent of the speed of rotation, either by differential pressure control of the rotors or by the variable incidence hydrofoils 21 and 23 which are arranged immediately in the wake of rotors. It will thus be appreciated that rotors which are mounted in tandem or side by side, as shown in FIG. 1, can, by applying differential hydrofoil deflections, effect stabilising and controlling moments in pitch and roll respectively, of the vehicle.

As is apparent from FIG. 6, the hyrofoils will also modify the performance of the rotor. Not only will it add to the lift and thrust or weight and drag depending on its incidence but it will also have an interference effect on the rear face of the rotor and the blades in the vicinity. It will be seen from FIG. 6 that because of the upward path of the water flow 77 after the rotor, the resultant force on a well-positioned hydrofoil 21 is capable of yielding a thrust represented by arrow 79 together with an additional lift force represented by arrow 81. The resultant force is represented by arrow 83. Alternatively, with the hydrofoil at an incidence near the normal direction to the flow (not shown), a considerable drag force can be produced.

In the illustrated construction, only one hydraulic motor is provided for each rotor. Torque is transmitted across the rotor partly by the hollow shaft 35, partly by the inner bag 57 and partly by the tie members 53. It is envisaged, however, that two hydraulic motors could be provided for each rotor. It is also envisaged that other forms of drive for each rotor could be provided.

Although the tie members 53 are shown as being parallel to each other and to the hollow shaft 35, this is not essential.

It is also envisaged that the end discs 39 and 41 need not be rigid. For example, they may be formed by a plurality of equal size S-shaped, resiliently deformable members angularly advanced and equally spaced, relative to each other about a common central point. An annular rim, also resiliently deformable, corresponding to the flange 63, would then be secured to the peripheries of the S-shaped members, and a flexible, gas impermeable membrane would then be secured to each side face, to correspond to the plates 49 and 51. A deformable end disc would result, and if a tread was secured to each such disc, the disc could act after the manner of an endless track, and could conform to a degree to the contour of land over which the vehicle was travelling. Alternatively, the end discs could be provided by a spoked wheel covered with fluid impermeable material.

Steering of the illustrated vehicle is by differential speed control and/or differential pressure control on the left and right hand pairs of rotors. It is also envisaged that steerable rotors could be used in an alternative arrangement.

Although the illustrated vehicle is rectangular in plan, it will be appreciated that plan forms other than rectangular are possible. Furthermore, instead merely of having a rotor at each of its corners, the rotors could be arranged in a different manner. For example, a large vehicle might require four or more rows of rotors along its length.

Although it is preferable that a hydrofoil be associated with each rotor, the rotor can be used without hydrofoils quite effectively.

In the preferred constructions, the rotors are gas filled to provide buoyancy for the vehicle. However, the rotors could be water filled, and used as the means of propulsion for a submarine in water and also on land, or even as the means of propulsion of a floating or otherwise supported water surface and land vessel. In this construction, it is preferred that the water pressure in the lower half of the rotors be less than that in the upper half, and this can be achieved by arranging a substantially horizontal plate across the centre of the rotors, and having a pump located in an aperture in the plate to control the pressures on either side of the plate.

Claims

What is claimed is:

1. An amphibious vehicle comprising a body, at least one rotor carried by said body for contributing to the support and for propelling said vehicle over land and water, and drive means for rotating said rotor, said rotor including a pair of laterally spaced end members, restraining means located between said end members adjacent to the periphery of said end members, a fluid impermeable flexible membrane extending between said end members, and means for securing said membrane to said end members in fluid-tight relation thereto, said membrane between said end members being secured to said restraining means at circumferentially spaced locations, whereby said membrane is radially deformable between said locations, means for internally pressurising said membrane to a pressure such that portions of said membrane between said locations when in contact with water will present a concave driving surface, a centrally located buoyancy chamber within the rotor, and wherein each end member has a peripheral surface for land travel.

2. A vehicle as claimed in claim 1 and including a central shaft connecting said end members and which rotates with the rotor, under the control of said drive means, and wherein the shaft is hollow and including at least one passage extending from the inside of the hollow shaft to the space defined by said membrane.

3. A vehicle as claimed in claim 1 in which a tread is mounted on said end members to provide said peripheral surface for travel on dry land.

4. A vehicle as claimed in claim 1 in which a controllable variable incidence hydrofoil is associated with the said at least one rotor and including means to locate said hydrofoil on that side of said rotor which is downstream when the vehicle is moving in a forward direction.