Anti-lock brake system with piezoelectric brake actuator

An electrical braking system, comprising:

• first friction braking means comprising;
• a first piezoelectric ceramic layer having opposing first and second major faces;
• and
• a first prestress layer bonded to said first major face of said piezoelectric ceramic layer;
• wherein said first prestress layer normally applies a compressive force to said first piezoelectric ceramic layer;
• a first moveable member to be braked;
• an electric controller for generating a first electrical output signal for operating said first friction braking means in accordance with brake force demand inputs, said electric controller having an input side and an output side;
• a first electrical conductor connected on a first end to said output side of said electric controller and on a second end across said first and second faces of said first piezoelectric ceramic layer of said first friction braking means;
• actuating means for generating a first brake force demand input signal for said controlling means, said actuating means comprising;
• a mechanical input device for generating a variable mechanical signal;
• an electrical signal generator for generating a first brake force demand input signal proportional to said variable mechanical signal;
• said electrical signal generator being in mechanical communication with said mechanical input device and in electrical communication with said input side of said electric controller;
• a first wheel slip sensing means for determining a first wheel-road slippage condition, said first wheel slip sensing means comprising:
• a first wheel speed sensor for sensing a peripheral wheel speed;
• said first wheel speed sensor having an output signal proportional to said peripheral wheel speed;
• first slip computing means for computing an acceleration and a vehicle body speed;
• said first slip computing means comparing said sensed peripheral wheel speed to said computed acceleration and said computed vehicle body speed to determine if said first wheel-road slippage condition exists;
• and
• first signal generation means for generating a second brake force demand input signal indicative of said first wheel-road slippage condition;
• said first signal generation means being in electrical communication with said input side of said electric controller;
• whereby electrically energizing said first friction braking means moves said friction braking means into contact with said first moveable member;
• and whereby a first braking force is generated by moving said first friction braking means into contact with said first moveable member.