| 摘要 |
959,825. Air cushion vehicles. HOVERCRAFT DEVELOPMENT Ltd. Sept. 30, 1960 [Oct. 2, 1959], No. 33535/59. Heading B7K. A vehicle for travelling over a surface and which, in operation, is supported above that surface, at least in part, by a cushion of pressurized gas formed and contained beneath the vehicle, comprises means for reducing the variations in vertical thrust exerted by the supporting gas cushion in the underside of the vehicle which would otherwise occur from variations in volume of the cushion as a result of variations in the height of the vehicle above the surface from a predetermined value. In its simple form, wherein the supporting cushion is formed in a space 1 by pressure air discharged from a duet 8, the end walls 6 are formed with apertures 11 normally closed by flap valves 11, the front one opening inwards and the rear one outwards, the doors being loaded to maintain the cushion pressure at an optimum value. If as the result of the vehicle passing over a surface trough whereby the cushion pressure is reduced below atmospheric pressure, the forward valve 9 will open to admit air to the cushion and thereby reduce the loss of lift. Similarly if the cushion pressure should exceed the predetermined value the rearward valve 10 will be forced open to restore the cushion pressure to normal. To dispense with walls 6 the valves may be located in upwardly and outwardly curving ducts which connect the bottom wall with the vertical walls (Fig. 4, not shown). An alternative embodiment (Figs. 5 and 6, not shown), employs a vertical central duct connection the cushion chamber with atmosphere and formed with transverse flaps which may pivot upwardly or downwardly in response to changes in cushion pressure against the restraint provided by centralizing springs. Instead of spring-biased valves, the cushion pressure may be used to control fluid pressure apparatus for adjusting the valves (Fig. 8, not shown). In the arrangement of Fig. 10 the annular supply port 43 is provided with a plurality of slide valves 44, each operated by an actuator 47. By this means the curtain may be thickened or attenuated with consequent variation in cushion pressure. Other embodiments disclose pivoted flap valves or slide valves associated with concentric annular supply ports in a recirculating curtain system and in still further embodiments, the area of the cushion may be varied as the height of the vehicle varies. Apart from cushion pressure adjustment may be in response to vertical velocity or accleration. Specifications 893,715, 919,350, 935,824 and 935,826 are referred to. |
