US3648799A - Fluid supported load systems - Google Patents

Fluid supported load systems Download PDF

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Publication number
US3648799A
US3648799A US3808A US3648799DA US3648799A US 3648799 A US3648799 A US 3648799A US 3808 A US3808 A US 3808A US 3648799D A US3648799D A US 3648799DA US 3648799 A US3648799 A US 3648799A
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United States
Prior art keywords
fluid
pressure
control
fluidic
cushion
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Expired - Lifetime
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US3808A
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English (en)
Inventor
Michael A B Young
George H Dunsmuir
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British Hovercraft Corp Ltd
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British Hovercraft Corp Ltd
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Publication date
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60V—AIR-CUSHION VEHICLES
    • B60V1/00—Air-cushion
    • B60V1/04—Air-cushion wherein the cushion is contained at least in part by walls
    • B60V1/043—Air-cushion wherein the cushion is contained at least in part by walls the walls being flexible
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60V—AIR-CUSHION VEHICLES
    • B60V1/00—Air-cushion
    • B60V1/11—Stability or attitude control
    • B60V1/12—Stability or attitude control by dividing the cushion

Definitions

  • ABSTRACT A method of pressure control for fluid cushion supported load'bearing platfonns, the system comprising sensors responsive to, and transmitting signals indicative of pressure fluctuations within the fluid support cushion, as a control flow to a fluidic network, the resultant output from the fluidic network being applied to a device which regulates the flow of pressurized fluid to the support cushion, thereafter providing control of the pressure therein.
  • a pressure control system to obviate parasitic oscillations in fluid supported load bearing platforms wherein variations in pressure within a fluid pressure cushion are sensed by at least one fluidic element, the output from which is utilized to actuate means for controlling the flow of fluid to said fluid cushion, thereby effecting a control on the pressure variations within said fluid cushion.
  • the invention resides in a pure fluid supporting system comprising a load carrying platform, one or more fluid support cushions disposed beneath said platform, a conduit conveying a supply of pressurized fluid to said support cushion or cushions, valve means positioned relative -to said conduit to control flow through said conduit, sensor means positionably responsive to pressure variations occurring within said fluid support cushions, fluidic control means utilizing signals from said sensor means to control the operation of said valve means.
  • a first method of utilizing the invention is shown, by way of example only, in
  • FIG. 1 of the accompanying drawings discloses diagrammatically a simple control system for a single hover pallet.
  • FIG. 2 A second utilization ofthe invention is disclosed in FIG. 2, where a more sophisticated system is employed to control a multi-cushion hover pallet;
  • FIG. 3 shows diagrammatically a modified form of system sensitive to movement ofa sprung mass.
  • FIGS. 4, 5 and 6 show further examples of the type of air cushion vehicle to which the control system of the invention may be used to advantage.
  • FIGS. 7 and 7A disclose two of many suitable types of amplifier for use with the invention.
  • a platform I has a diaphragm 2 of flexible material attached to its underside by airtight joints at points 3 and 4. It is to be understood that only one half of an air cushion pad is illustrated in the drawing, and that the diaphragm 2 is symmetrical about a centerline 5, thus the securing point 3 is at the center of the diaphragm and the securing point 4 is at the periphery ofthe diaphragm.
  • Air at superatmospheric pressure is supplied to the space between the diaphragm 2 and the platform by way of supply pipe 11 and orifice 6.
  • An orifice 7 in the diaphragm 2 provides a passage for the air into the cushion area 8.
  • the fluidic control system shown utilizes a single proportional amplifier l3.
  • This amplifier may, of course, be of any conventional type as there are numerous suitable types availa ble, e.g., fully vented jet interaction beam deflection am plifiers (FIG. 7), vented pressure interaction beam deflection amplifiers, wall attachment devices, and vortex amplifiers (FIG. 7A),etc.
  • the initial problem to overcome originates in the pressure area defined by the platform, diaphragm and ground.
  • the fluid at a certain stage becomes active, that is, a parasitic oscillation develops within the fluid support pad.
  • the pressure at which this occurs may be dependent upon many variables, for example, weight carried by the platform, ground clearance, position of C. of 6., etc.
  • a pressure fluctuation is sensed within chamber 14 by a pressure sensor, this again may be of any convenient type, in the embodiment a pitot sensor 15 is used.
  • the fluidics are supplied with power fluid from a tapping 16 in the main supply conduit 11, the flow is first filtered at 17 before passing through supply lines 18, 19 and 20 to the fluidamplifier 13.
  • Pressure line 18 also supplies a pressure flow to pitot sensor 15 at supply pressure. This ensures that no dust or dirt particles can pass from the cushion area, back up through line 18 into the fluidic system. Any parasitic pulsing within the pressure support pad transmits pressure waves through sensor 15, line 18 and control lines 21 and 22 to control jets 23 and 24 of element 13.
  • an adjustable bias pressure is continuously fed through line 20 and variable restrictor 26, and supplies control jet 27.
  • This bias initially deflects the power stream from power nozzle 28 through outlet 29, which feeds chamber 30 in a double acting control valve 31, for the specific purpose of retaining this valve in an open condition.
  • This valve is preset such that, under normal operating conditions, element switching cannot take place, but as soon as bounce" occurs, the pressure wave through control jet 23 will overcome the bias, and switch the power stream to flow through outlet 32.
  • the power stream then passes through line 33 feeding chamber 34 of valve M, which, tending now to close, reduces the flow of pressurized fluid through conduit 11.
  • This partial drop in supply pressure is sufficient to substantially eliminate this bounce" characteristic and, thereafter assists in controlling the support pad pressure at an operational level.
  • the system is vented at 35 and 36 through restrictors 37 and 38. This prevents back pressures from decreasing the efficiency of element 13.
  • Restrictors 39 and 40 are positioned in control lines 2ll and 22 to adjust the control stream, but it will be obvious that these may be dispensed with, or others introduced throughout the circuit, as required.
  • FIG. 2 Whilst it is envisaged that on a multi-pad arrangement, one such system, effective on one of the support pads, may be sufficient to overcome bounce," a more sophisticated arrangement can be seen in FIG. 2.
  • the first element 45 of a three-stage proportional amplifier is permitted to sense pressure fluctuations from pads 41 and 42 in a similar manner to that previously described in relation to element 13 of FIG. 1. Pressure fluctuations occurring in either pads 43 or 44 are sensed by elements 46 and 417 respectively.
  • the preset bias pressure is, for convenience, effective on element 47, thus maintaining the valve 31 in the open condition.
  • a third embodiment is shown in FIG. 3, and utilizes a single fluidic element 48.
  • the element does not sense pressure change from within the fluid cushion, but senses the movement of a sprung mass 49 in relation to vertical oscillations of the platform 1 caused by pressure variations within the supporting cushion.
  • Additional stages of amplification incorporating feedback circuits, resistors, and extra accumulators, may be added as required.
  • the valve 31 is shown separate from the main supply control valve (not shown) which is operated generally by the pallet operator. This, however, need not be the case, the signals from the amplifier could be fed directly into the main supply control valve, carrying out the necessary control without the requirement of an additional valve.
  • FIGS. 4, and 6 are introduced to show that the control system of the present invention can be utilized in other than a simple load pallet arrangement.
  • FIG. 4 an air cushion vehicle is shown where the supporting cushion is bounded by a flexible skirt 70 and divided into a number of separate compartments 7] by longitudinally and laterally extending wall members 72 and 73.
  • the control system preferably would employ a pressure sensor positioned in each compartment, and the fluidic arrangement would be similar to that disclosed in FIG. 2.
  • FIG. 5 a I-Iovercraft having a multiplicity of support cushions is disclosed. Pressurized fluid is supplied to each air cushion 74, which is bounded by a skirt member. Sensors may be employed within each cushion area, as previously described.
  • FIG. 6 a tracked air cushion vehicle is shown which utilizes the hover pallet principle.
  • support is achieved by diaphragm type pallets 75; these could extend the entire length of the vehicle, on either side, or the support system could include a large number of such supporting diaphragms.
  • the control system of the invention would substantially stabilize the vehicle and maintain an even distribution of fluid to each support cushion.
  • a power stream is fed into power nozzle 65 and control streams are fed into control jets 66 and 67.
  • Items 68 and 69 are vents and 70 and 71 are outlets.
  • Variable deflection of the power stream from power nozzle 65 is achieved within the amplifier in response to changes in control stream energies. When there is a difference of pressure between the control streams, deflection will cause more of the power stream to flow into one of the outlets than the other. Vents 68 and 69 vent the power stream under maximum and overload conditions and when the load is zero.
  • the vortex amplifier or valve shown in FIG. 7A also suitable for use in the invention, operates as follows:
  • the power stream 72 is introduced through power nozzle 73 at the outer wall of the vortex chamber, and is orientated to flow radially inwards towards the center outlet 74.
  • the control jet 75 is located near the power nozzle 73 and the control stream is directed perpendicularly against the power stream 72.
  • control stream If no control stream is present the power stream flows directly to the outlet, giving maximum output.
  • a control stream When a control stream is introduced it deflects the power stream 72 away from its radial path to establish a spiral pattern as shown. The deflection of the power stream, and subsequent formation of the vortex, lengthens the flow path and increases the acceleration of the power stream, which increases the pressure drop, the output being a variable factor decreasing with the increase of control pressure.
  • a pressure control system to obviate parasitic oscillations in the supporting cushion comprising sensor means responsive to pressure variations in said supporting cushion for emitting output signals in accordance with such pressure variations, and fluidic control means responsive to signals from said sensor means for reducing the supply of pressurized fluid to said supporting cushion in response to predetermined signals from said sensor means, said fluidic control means comprising, in combination, fluid amplifier means and pneumatically operated valve means, said fluid amplifier means being responsive to signals from said sensor means and providing pneumatic control outputs to operate said valve means, said fluid amplifier means includes a fluidic element having a power nozzle for emitting a power stream, at least one outlet aperture, and at least one control jet for emitting a control stream to interact with the power stream and vary its path relative to said at least one outlet aperture so as to vary the output therefrom.
  • said sensor means comprises means for sensing vertical oscillations of said platform caused by pressure variations in said supporting cushion.

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  • Engineering & Computer Science (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Vibration Prevention Devices (AREA)
  • Fluid-Damping Devices (AREA)
  • Bridges Or Land Bridges (AREA)
  • Combined Devices Of Dampers And Springs (AREA)
  • Magnetic Bearings And Hydrostatic Bearings (AREA)
US3808A 1969-01-21 1970-01-19 Fluid supported load systems Expired - Lifetime US3648799A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB329969 1969-01-21

Publications (1)

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US3648799A true US3648799A (en) 1972-03-14

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US3808A Expired - Lifetime US3648799A (en) 1969-01-21 1970-01-19 Fluid supported load systems

Country Status (5)

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US (1) US3648799A (enrdf_load_stackoverflow)
CA (1) CA930700A (enrdf_load_stackoverflow)
DE (1) DE2001831A1 (enrdf_load_stackoverflow)
FR (1) FR2033251A7 (enrdf_load_stackoverflow)
GB (1) GB1258191A (enrdf_load_stackoverflow)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3857456A (en) * 1973-04-30 1974-12-31 Little Syst Inc Air cushion craft air supply
US3867994A (en) * 1973-09-10 1975-02-25 Sun Oil Co Surface effect vehicle control system
US3893538A (en) * 1970-08-10 1975-07-08 J Dale Thompson Ground effects vehicle and an air terminal
US4455945A (en) * 1982-07-06 1984-06-26 Airail Systems, Inc. Air bearing power and traction drive system
EP0148502A3 (en) * 1984-01-03 1986-03-05 Delu-Luftkissen-Transportgeratetechnik Gmbh Pressure air control system for an air pallet
US6530444B2 (en) * 2000-04-18 2003-03-11 Otis Elevator Company Controlled levitation vehicle

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2388756A1 (fr) * 1977-04-29 1978-11-24 Creusot Loire Grue de forte capacite equipee d'un dispositif d'equilibrage
FI69605C (fi) * 1984-06-21 1986-03-10 Solving Ky System foer automatisk tryckreglering av luftkuddeelement

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3297102A (en) * 1963-06-21 1967-01-10 Hovercraft Dev Ltd Air cushion vehicles having attitude-correcting skirts
US3340943A (en) * 1965-05-07 1967-09-12 Bertin & Cie Air cushion stability control device with adjustable plenum chamber volume
US3373837A (en) * 1965-02-01 1968-03-19 Bertin & Cie Feed systems for multiple air cushion type platforms
US3439772A (en) * 1965-12-29 1969-04-22 Bertin & Cie Surface effect devices with fluid amplifier stabilizing means
US3513935A (en) * 1967-06-01 1970-05-26 British Hovercraft Corp Ltd Air cushion supported platforms

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3297102A (en) * 1963-06-21 1967-01-10 Hovercraft Dev Ltd Air cushion vehicles having attitude-correcting skirts
US3373837A (en) * 1965-02-01 1968-03-19 Bertin & Cie Feed systems for multiple air cushion type platforms
US3340943A (en) * 1965-05-07 1967-09-12 Bertin & Cie Air cushion stability control device with adjustable plenum chamber volume
US3439772A (en) * 1965-12-29 1969-04-22 Bertin & Cie Surface effect devices with fluid amplifier stabilizing means
US3513935A (en) * 1967-06-01 1970-05-26 British Hovercraft Corp Ltd Air cushion supported platforms

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3893538A (en) * 1970-08-10 1975-07-08 J Dale Thompson Ground effects vehicle and an air terminal
US3857456A (en) * 1973-04-30 1974-12-31 Little Syst Inc Air cushion craft air supply
US3867994A (en) * 1973-09-10 1975-02-25 Sun Oil Co Surface effect vehicle control system
US4455945A (en) * 1982-07-06 1984-06-26 Airail Systems, Inc. Air bearing power and traction drive system
EP0148502A3 (en) * 1984-01-03 1986-03-05 Delu-Luftkissen-Transportgeratetechnik Gmbh Pressure air control system for an air pallet
US4607715A (en) * 1984-01-03 1986-08-26 Delu-Luftkissentransportgeratetechnik Gmbh Proportional pneumatic control system for aircushions
US6530444B2 (en) * 2000-04-18 2003-03-11 Otis Elevator Company Controlled levitation vehicle

Also Published As

Publication number Publication date
DE2001831A1 (de) 1970-10-22
FR2033251A7 (enrdf_load_stackoverflow) 1970-12-04
GB1258191A (enrdf_load_stackoverflow) 1971-12-22
CA930700A (en) 1973-07-24

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