Motor vehicles – Surface effect vehicles – Having propulsion or control means
Patent
1995-07-19
1997-08-12
Hurley, Kevin
Motor vehicles
Surface effect vehicles
Having propulsion or control means
180118, B60V 111
Patent
active
056556160
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a surface effect vehicle, in particular a waterborne vehicle, with a plurality of lift fans for generating an air cushion, each fan having a drive with a motor and a regulating circuit with corresponding sensors and actuators for acting on the air cushion. Further, the invention is directed to a process for regulating an air cushion in a surface effect vehicle with a plurality of lift fans whose drives have regulators and motors which are operated at a determined speed for generating an air cushion of a determined pressure or height and deliver a corresponding output, the behavior of the lift fans conforming to a determined characteristic curve.
A surface effect vehicle of this type is known, for example, from DT 36 38 785. The waterborne vehicle described therein has a plurality of lift fans for generating an air cushion, each fan having a drive with a motor and a regulating circuit which is linked with a computer and has sensors for influencing the air cushion.
The control can respond in various ways by suitable programming depending on the aim of optimization. However, this reference does not explain the precise way in which the drives are to be regulated as a function of the selected optimizing criterion.
The vertical fluctuations resulting from fluctuations in pressure cannot be eliminated by the known regulating devices of lift fans, especially when a plurality of lift fans are operated in parallel. This is because oscillations which can destroy the lift fans and other components occur constantly during parallel operation of the lift fans.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a hovercraft which avoids the disadvantages of the prior art.
More particularly, it is an object of the present invention to provide a surface effect vehicle and a process for operating lift fans which enables economical operation and an improved performance of the vehicle.
This object is met according to the invention by a surface effect vehicle in which each drive has an associated regulating circuit and the drive of a first lift fan is operated as a guiding drive or master drive while the rest of the lift fans are operated as follower drives.
The oscillations of the drives observed when lift fans are operated in parallel are prevented in this way. Every additional lift fan has its own drive with associated regulating circuits and the drive of the first lift fan is operated as a master drive, while the rest of the lift fans are operated as follower drives. The regulators are operated in such a way that one or more of the other fans is so regulated, depending on the output of the master drive, that the ventilator speed is adjusted in proportion to the square of the difference of the total volume flow of all parallel lift fans divided by the number of lift fans in parallel operation minus the volume flow of the regulated fan. More simply, the volume flow is measured and regulated. This essentially corresponds to a regulation of output, since the product of volume flow and air cushion pressure corresponds to output.
The measured output signal or speed signal or volume flow signal of the first lift fan is applied to the follower drives as a guide signal. The master regulating circuit is preferably a pressure regulating circuit or position regulating circuit and the follower regulating circuits are preferably speed regulating circuits or output regulating circuits or volume flow regulating circuits. The signal for the volume flow is preferably transmitted over a certain period of time which corresponds to a filtering. In so doing, the measured signal is not filtered directly, but rather the results of the regulating signal obtained after squaring are filtered.
Very brief disturbances, e.g., in the form of an individual wave, can be eliminated by regulation and ride quality can be increased when an additional pressure regulating circuit having a time component smaller than a time constant of a follower regulating cir
REFERENCES:
patent: 3889775 (1975-06-01), Luscher
patent: 4103755 (1978-08-01), Tattersall
Allison et al., Navy Technical Disclosure Bulletin, vol. 5, No. 5, pp. 51-54 May 1980.
Witt Hans
Witt Henrik
Witt Karsten
Hurley Kevin
Striker Michael J.
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