Antiskid brake control for aircraft
First Claim
1. An antiskid control circuit for aircraft having an antiskid valve for controlling the braking of the wheels thereof by regulating the application of brake pressure, and a transducer for each wheel producing wheel speed signals indicative of the instantaneous rotational speed of the associated wheel, comprising:
- deceleration detection means connected to and receiving the wheel speed signals from the transducers for presenting an output signal when the rate of deceleration of a wheel exceeds a predetermined threshold;
a valve driver interconnected between said deceleration detection means and the antiskid valve and responsive to said output signals to release brake pressure;
a modulator interconnected between said deceleration detection means and said valve driver, responsive to said output signal to further release brake pressure and then increase brake pressure at a predetermined rate following said release; and
wherein said valve driver includes gain control circuitry responsive to said deceleration detection means and said modulator to modify the effect of the modulator and deceleration detection means on the antiskid valve as a function of the amplitude and frequency of occurrence of said output signal.
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Accused Products
Abstract
An antiskid brake control wherein sensitive deceleration detectors present output signals to a valve driver for releasing brake pressure. The deceleration detector output is also passed to a modulator which acts as a memory circuit to keep the average brake pressure near the skid level and also provides for a controlled reapplication of brake pressure following the release. A constant current discharge circuit is connected to the modulator to provide a linear discharge of the modulator capacitor. A fast recovery circuit is interconnected between the deceleration detector and modulator to rapidly discharge the modulator capacitor in the event that no outputs from the deceleration detector have been sensed for a predetermined period of time. The control system includes gain control circuitry to provide for at least three distinct system gains. Also provided as a portion of the invention is touchdown protection circuitry which holds brake pressure off when the aircraft is in the air and for a fixed time period following touchdown, unless the wheels have spun-up past a predetermined rotational speed. Such circuitry further controls reapplication of the antiskid system to the braking effort following a bounce of the braked wheels.
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Citations
35 Claims
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1. An antiskid control circuit for aircraft having an antiskid valve for controlling the braking of the wheels thereof by regulating the application of brake pressure, and a transducer for each wheel producing wheel speed signals indicative of the instantaneous rotational speed of the associated wheel, comprising:
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deceleration detection means connected to and receiving the wheel speed signals from the transducers for presenting an output signal when the rate of deceleration of a wheel exceeds a predetermined threshold; a valve driver interconnected between said deceleration detection means and the antiskid valve and responsive to said output signals to release brake pressure; a modulator interconnected between said deceleration detection means and said valve driver, responsive to said output signal to further release brake pressure and then increase brake pressure at a predetermined rate following said release; and wherein said valve driver includes gain control circuitry responsive to said deceleration detection means and said modulator to modify the effect of the modulator and deceleration detection means on the antiskid valve as a function of the amplitude and frequency of occurrence of said output signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. In an antiskid control circuit for aircraft having an antiskid valve for controlling the braking of the wheels thereof by regulating the application of brake pressure, and a transducer for each wheel producing wheel speed signals corresponding to the instantaneous rotational speed of the associated wheel, the improvement of deceleration detection means, comprising:
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a capacitor receiving the wheel speed signals and producing a deceleration signal corresponding to the deceleration rate of the associated wheel; an amplifier connected to said capacitor and receiving said deceleration signal; and threshold circuit means connected to said amplifier and operatively connected to said capacitor for establishing a predetermined threshold, said amplifier producing an output when said deceleration signal exceeds said threshold, and wherein said threshold circuit is connected between first and second voltage levels and to a first input of said amplifier, said capacitor being connected to a second input of said amplifier, and which further includes first circuit means interposed between said capacitor and said second input and interconnected between said first and second voltage levels for providing a stable voltage differential between said first and second inputs. - View Dependent Claims (28, 29)
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30. In an antiskid control circuit for aircraft having an antiskid valve for controlling the braking of the wheels thereof by regulating the application of brake pressure, a transducer for each wheel producing wheel speed signals corresponding to the rotational speed of the associated wheel, and deceleration detection means connected to each transducer and producing an output when the deceleration rate of the associated wheel exceeds a particular level, the improvement of a modulator, comprising:
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a charging capacitor; a first diode interconnected between said charging capacitor and the deceleration detection means, said first diode having a characteristic voltage drop associated therewith; and an amplifier having a second diode interconnected between an input and the output thereof, said amplifier being interconnected between said first diode and said deceleration detection means for receiving and changing the amplitude of said output signal by said characteristic voltage drop. - View Dependent Claims (31)
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32. In an antiskid control circuit for aircraft having an antiskid valve for controlling the braking of the wheels thereof by regulating the application of brake pressure, and deceleration detection means operatively connected to each wheel and producing an output signal when the deceleration rate of the associated wheel exceeds a particular level, the improvement comprising:
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a modulator including a modulator capacitor operatively connected to and receiving said output signals from the deceleration detection means; and circuit means interconnected between said modulator capacitor and said deceleration detection means for discharging said modulator capacitor when no output signals are emitted from said deceleration detection means for a particular time period, said circuit means comprising; a charging circuit connected to said deceleration detection means, receiving said output signals and charges therefrom; a discharge circuit connected to said charging circuit, providing a discharge path for said charge and tending to constantly reduce said charge; and comparator circuit means connected to said charging circuit and to said modulator capacitor for comparing said charge with a predetermined voltage level, and providing a discharge path for said modulator capacitor when said charge exceeds said predetermined voltage level. - View Dependent Claims (33, 34, 35)
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Specification