| 摘要 |
A brake system using a pair of brake apply and release force units, the units having electric motors with non-backdriveable mechanical output members to supply the needed brake apply force to limit of capability of the motors. Piezoelectric elements that generate high forces with low expansion during rapid rates of change of applied voltage are positioned in brake apply force-transmitting series with the motor output members. These elements are alternately energerized with applied voltage and deenergized, in opposite phase relation. The piezoelectric expansion effect of each energized element is mechanically captured in each energization cycle by the motor unit having the deenergized element so that the brake apply forces actually applied to actuate the brake are increased well beyond the maximum output of the motors. This is obtained by the alternating energization of the piezoelectric elements and the alternating follow-up actions of the motors, with the non-backdrivable arrangements acting to store the mechanical force increases so attained. Wheel lock control may be attained. When actuated, this feature sets the output force generated by the motors, deenergizes the piezoelectric elements, and then concurrently energizes and deenergizes them to obtain a brake pumping action while preventing excessive wheel slip.
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