US3444951A - Plural cushion load transporter device - Google Patents

Description

May 20, 1969 L A. HOPKINS PLURAL CUSHION LOAD TRANSPORTER DEVICE I Filed June 7. 1967 .x I I ll M II JNVENTOB L. A HOPKINS A TTOMYS' C diz/10%, M14,

United States Patent r 3,444,951 PLURAL CUSHION LOAD TRANSPORTER DEYICE Leslie Arthur Hopkins, Dihden Pnrlien, England, assignor to Hovercraft Development Limited, London, England, a British company Filed June 7, 1967, Ser. No. 644,182 Claims priority, application Great Britain, June 15, 1966, 26,745/ 66 Int. Cl. B60v 1/02 US. Cl. 180-121 4 Claims ABSTRACT OF THE DISCLOSURE A load transporter comprises a platform supported by a series of ground-following air-cushioned units of plenum chamber form, the cushion of each unit being contained by an inwardly tapering flexible skirt. The units are urged towards the ground by constant load springs and in normal operation the downward loading of a spring is balanced by the upward thrust of a cushion, the bottom of each skirt being collapsed against the ground.

If an air cushion unit encounters a depression in the ground which allows the collapsed bottom portion of its skirt to extend, as the cushion area is then decreased the downward loading of the spring overrides the reduced upward thrust of the cushion so that the unit is moved down to follow the ground. Should the unit encounter a ground protuberence whereby the skirt bottom portion is further collapsed, as this results in an increase in cushion area the increased upward thrust of the cushion overrides the spring to move the unit away from the ground.

This invention relates to gas-cushion load-carrying devices and is particularly applicable to any of the gascushioned load-carrying devices described and illustrated in copending U.K. application 20,897/ 66.

Copending U.K. application 20,897/ 66 discloses a gascushioned load-carrying device comprising a load-carrying-structure having on its bottom surface a plurality of flexible inflatable wall structures of annular form each defining within its periphery a gas-cushion space which is closed at its upper part, bounded around its sides by the wall structures and open at its lower part, and means for introducing pressurised gas into each cushion space to form a gas-cushion therein to produce a ground-effect support for the vehicle, each wall structure comprising a succession of separate, flexible wall members each defining a concavity, the hollow of which is presented towards the cushion space, side portions of each wall member being contiguous with the adjacent side portions of a neighbouring wall member, the side portions serving as tie means for constraining the wall members against deflection away from the cushion space by cushion pressure, the arrangement being such that cushion gas enters the concavities of the Wall members to inflate the wall members and in so doing urge the contiguous side portions of neighbouring wall members towards each other.

In a preferred embodiment of UK. application 20,897/ 66, at least the bottom portions of the wall members defining the concavities thereof are inclined inwardly towards their associated cushion space and it has been observed that because of this inward inclination, should the bottoms of the flexible wall members be made to collapse slightly by lowering the cushion pressure so that compressive forces are applied to the wall member bottoms as a result of contact with the ground surface, the upwardly acting force applied to the load-carrying structure by the cushion is increased slightly due to the increase in the effective area of the cushion.

The present invention makes use of this observation and provides a gas-cushioned load-carrying device adapted to negotiate ground surface irregularities of substantial size.

According to the invention, a gas-cushioned load-carrying device comprises a load-carrying structure provided with a plurality of gas-cushion support units each of which has a flexible, cushion-bounding wall structure of inflatable construction and of annular form which, in operation, defines a gas-cushion space open to the ground surface beneath the device, at least the bottom of each wall structure inclining inwardly towards the cushion spaced defined by the wall structure so that downward movement of a wall structure beyond initial contact with the ground surface increases the effective area of its cushion space, the units being provided with means responsive to changes in the upwardly-acting thrusts exerted by the gas-cushions of the units whereby a decrease in the elfective area of the cushion space of a unit results in the associated wall structure being moved downwardly towards the ground surface, and an increase in said effective area results in the wall structure being moved upwardly away from the ground surface.

The device may include means for introducing pressurised gas into each cushion space to form a gas-cushion therein at suflicient pressure to produce ground-effect support for the structure, but such as to provide initial collapse of the wall structure bottom portion against the ground surface, the means responsive to changes in the upwardly-acting thrusts exerted by the gas-cushions of the units may comprise a substantially constant load resilient connection between the load-carrying structure and each gas-cushion support unit arranged to urge the units downwardly, to balance the upwardly-acting thrusts exerted by the gas-cushions whereby, in the event of a reduction in the effective area of a cushion space, the downward force applied by the associated resilient connection overrides the upwardly-acting thrust exerted by the gas-cushion so as to move the associated wall structure downwardly against said thrust and, in the event of an increase in said effective area, the upwardly-acting thrust exerted by the gas-cushion overrides the downwardly acting force applied by the connection so as to move the wall structure upwardly against said downwardly-acting force.

An embodiment of the invention will now be described by way of example with reference to the accompanying drawings wherein:

FIGURE 1 is a side view of a gas-cushioned loadcarrying device,

FIGURE 2 is an enlargement of the box II of FIGURE 1 with added detail, and

FIGURE 3 is a detail illustrating one operating condition of an inflatable wall structure.

With reference to FIGURES 1 and 2, a gas-cushioned load-carrying device in the form of a transporter 1 comparts enclosed by prises a load-carrying structure or body 2 carrying a large, heavy load 3, connected by a demountable coupling to the cab 4. The body 2 and cab 4 have road wheels 5 but these are provided only for traction and stability, substantially the whole of the load 3 being taken by a plurality of air-cushion support units 25 disposed in five spaced rows (four units 25 to a row) beneath the body 2 with each unit 25 resiliently connected thereto by a substantially constant load hydraulic spring unit 7. As explained hereinafter, the hydraulic spring units 7 are responsive to changes in the upwardly-acting thrusts exerted by the air-cushions of the units 25. Each air-cushion support unit 25 has a cushion-containing flexible wall structure 6 of the form described and illustrated in copending U.K. application 20,897/66. copending coassigned US. application Ser. No. 566,948, filed July 21, 1966, also gives details of wall structures similar to the wall structure 6 and should also be referred to.

Briefly, each of the wall structures 6 is of annular form, each defining within its periphery an air-cushion space 8 which is closed by a base 9 at its upper part, bounded around its sides by the wall structure itself and open to the ground surface 10 at its lower part. Pressurised air is fed to the cushion space 8 to produce ground-effect support for the transporter body 2 by a flexible hose 11 connecting the space 8 with one of a pair of air supply ducts 12 extending lengthwise along the sides of the body 2. The ducts 12 are connected to an air supply unit 13 mounted in the body 2 and comprising a casing 14 housing a fan 15 driven by a variable speed motor 16.

Each wall structure 6 comprises a succession of flexible wall members 17 each attached along its upper edge 18 to the associated base 9. The wall members 17 are separate from each other so as to be deflectable relative to each other. Each wall member 17 comprises a single fold of thin, light, sheet material defining a concavity, the hollow of which is presented to the associated cushion space 8.

The side portions 19 of a wall member 17 are contiguous with the adjacent side portions of a neighbouring wall member to form a cushion seal and serve as tie means for constraining the wall member against deflection away from the cushion space 8 by cushion pressure which inflates the wall members. The whole of the outer portions 20 of the wall members incline inwardly towards the cushion space 8. The resultant of the inflation loads acting on the outer portions 20 passes between the extremities of the upper edges 18, i.e. the extremities of the attachment points between the wall members 17 and the bases 9. Thus the inflation loads apply only substantially tensile loads to the thin, light, wall members 17. However, as will be understood from the teachings of copending US. application Ser. No. 566,948, providing the side portions 19 fulfill their functions in providing constraint, the whole of each outer portion 20 need not incline inwardly.

With reference now to FIGURE 2, under normal conditions, the air supply unit 13 supplies cushion air at substantially constant pressure sufiicient to produce groundefi'ect support for the body 2. The setting of the constant load hydraulic spring units 7 and the cushion pressures in the spaces 8 are such that the air-cushion units are held in positions wherein the bottom portions of the wall members are urged downwardly, towards the surface 10 beyond initial contact and are thus initially collapsed by compressive forces applied to the bottoms by contact with the surface 10. In these positions, the upwardly-acting thrusts exerted by the air-cushions in the spaces 8 are balanced by the downwardly-acting forces applied by the spring units 7. The degree of collapse and thus the positions of equilibrium can be varied by controlling the speed of the motor 16.

With the vehicle travelling in the direction of the arrow 22, should an air-cushion support unit 25 encounter a concavity 23 in the ground surface 10, the bottom portions of the wall members 17 of the unit will be freed of contact with the surface 10 and so are extended by cushion pressure. The balance between the upwardly-acting thrust of cushion pressure in the cushion space 8 (which pressure remains substantially constant) and the downwardly-acting force applied to the unit 7 is therefore upset by the resulting decrease in the elfective area of the cushion space, whereby the downwardly-acting force applied by the constant-load spring unit 7 overrides the upwardly-acting thrust exerted by the gas-cushion in the space 8. This results in the air-cushion support unit 25 being moved downwardly, towards the surface 10, and against said thrust until an equilibrium position is reached wherein the bottom portions of the wall members 17 are again collapsed by contact with the ground surface 10, and to substantially the same extent as before.

With reference now to both FIGURES 2 and 3, should the vehicle encounter the ground surface protuberence 24, the bottom portions of the wall members 17 will be further collapsed by contact with the surface of the protuberence 24, as the hydraulic spring unit 7 initially attempts to hold the wall structure 6 in the same position as before. This results in an increase in the effective area of the cushion space 8 and, as the pressure of the cushion therein is substantially constant, the upwardly-acting thrust exerted by the cushion overrides the downwardly-acting force applied by the hydraulic spring unit 7 whereby the wall structure 6 is moved upwardly, away from the ground surface 10, and against said force, until a new position of equilibrium is reached.

The invention provides a ground following wall struc ture enabling the load-carrying device to which it is attached to negotiate ground-surface irregularities of substantial size.

I claim:

1. A load-carrying device comprising a load-carrying structure, means for mounting a plurality of gas-cushion support units beneath said structure for vertical move ment relative to each other and relative to said structure, each of said units comprising a base and a depending peripheral wall structure defining a gas-cushion space beneath said base open to the surface over which the device is to operate, at least the bottom portion of each wall structure being inclined inwardly towards the cushion space defined thereby and being vertically collapsible so as to collapse progressively upon contact with said surface, so that the operative plan area of the cushion varies in dependence on the degree of collapse of the wall structure, being progressively increased as the wall structure is collapsed, and means for supplying gas under pressure to the cushion spaces of said units wherein the pressure in said spaces remains substantially constant, saidmounting means comprising means for applying to each of said units a substantially constant downward bias irrespective of the vertical movement of each said unit relative to said load carrying structure, the load applied by the biasing means to each unit being such as to be balanced by the upwardly acting force exerted by the cushion of said unit when the wall structure containing the cushion is in a predetermined position in relation to said surface.

2. A device as claimed in claim 1 wherein the predetermined position of the wall structure of each unit is that in which the wall structure is partially collapsed by contact with the surface over which the device is to operate.

3. A device as claimed in claim 1 wherein said biasing means comprises a constant load hydraulic spring unit interposed between the load-carrying structure and each of the gas-cushion support units.

4. A device as claimed in claim 1 wherein the wall structures each comprise a succession of inflatable wall members defiectable relative to each other, each wall member defining a concavity, the hollow of which is presented to the associated gas-cushion space, the wall members having side portions contiguous with the adjacent side portions of a neighbouring wall member and serving as tie means for constraining the wall member against deflection away from the cushion space by pressure of the gas-cushion therein.

References Cited UNITED STATES PATENTS Cockerell 180-1 18 Eggington et a] 180121 Guienne 180121 X Bertin et a1 180127 6 3,353,617 11/1967 Hopkins 180127 3,385,390 5/1968 Guienne 1804-116 FOREIGN PATENTS 1,338,368 8/1963 France.

A. HARRY LEVY, Primary Examiner.

US. Cl. X.R. 1801 19

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