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Title: Devices for controlling carbon disc brakes, more particularly for aircraft
Claims: We claim: 1. A device for controlling the braking pressure of a carbon disc brake as for example in undercarriages of aircraft carrying a heavy load comprising at least one tachometric dynamo for determining the rotational speed of a disc of a brake, an inverted time-delay means acting to increase the pressure in the disc brake, means for applying the output of said dynamo to said delay means, a brake control means including a potentiometer with its output signal applied to the input of an operational amplifier followed by a second similar amplifier, said two amplifiers having a common negative feedback connection so as to operate as follower amplifiers for controlling braking pressure via a solenoid valve, the direct connection between the output of said first amplifier and said second amplifier comprising a diode which opposes the direct flow of current and a capacitor in parallel beyond said diode towards said second amplifier, and means controlled by voltage of said tachometric dynamo so as to modify the charging state of said capacitor if there is a variation in the input voltage of said first amplifier. 2. A device according to claim 1, wherein the tachometric dynamo voltage is applied in parallel to one input of a number of differential amplifiers whose other input if polarised in dependence on a speed threshold so as to change the sign of the output voltage of the corresponding differential amplifier when the threshold is passed, the output voltage of said differential amplifiers controlling a charge of the capacitor. 3. A device according to claim 2 wherein the means controlled by the tachometric dynamo voltage modifying the charge of the capacitor comprise a transistor controlled by the output of an operational amplifier forming a relay, one input thereof receiving a reference voltage from the tachometric dynamo and the otherinput being directly connected to the transistor output remote from the capacitor and to a ballast resistor. 4. A device according to claim 3, wherein the output voltage of the second follower amplifier is applied to a differential amplifier whose other input receives a reference voltage equal to the voltage level corresponding to a given pressure state in the braking device, the output voltage of the differential amplifier being applied to the control electrode of a transistor biased by a voltage corresponding to the maximum possible level of the rate of pressure increase, the output of the transistor being connected to the input of the operational amplifier forming a relay. 5. A device according to claim 2, wherein the output of one of the differential amplifiers controls a transistor biased by a voltage corresponding to the minimum level of the rate of pressure increase. 6. A device according to claim 2, wherein the diode providing a direct connection is shunted by a transistor whose control electrode is connected to the output of one of the differential amplifiers adjusted for a very low speed-threshold value. 7. A device according to claim 6, wherein the shunt circuit of the connecting diode comprises an additional resistor determining the rate of variation in the loading of the capacitor by the transistor. Other info: Inventors: Gentet, Pierre (Colomiers, FR) Signorelli, Louis (Toulouse, FR) Geoffroy, Alain Yves Louis Marcel (Toulouse, FR) Application Number: 500737 Filing Date: 1974-08-26 Publication_date: 1976-04-06 Assignee: Societe Nationale Industrielle Aerospatiale (Paris, FR) Primary Class(es): 303/159 244/111, 303/20, 303/126 Other Classes: US Patent Ref:
Other Refs: Primary Examiner: Blix, Trygve M. Assistant Examiner: Kunin, Stephen G. Attorney: Flocks; Karl W. |
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