Brake system apparatuses, methods, and arrangements

A brake system for actuating a plurality of wheel brakes in a normal non-failure braking mode and in a backup braking mode, the brake system comprising:

• an MC power transmission unit having a first electric motor for at least partially pressurizing hydraulic fluid;
• first and second output lines for routing the pressurized hydraulic fluid from the MC power transmission unit;
• an iso/dump control valve arrangement associated with each wheel brake of the plurality of wheel brakes;
• a first traction control iso valve hydraulically interposed between the MC power transmission unit and at least one iso/dump control valve arrangement via the first output line;
• a second traction control iso valve hydraulically interposed between the MC power transmission unit and at least one iso/dump control valve arrangement via the second output line;
• a pump piston associated with at least one wheel brake of the plurality of wheel brakes, the pump piston being driven by a second electric motor for selectively providing pressurized hydraulic fluid to the iso/dump control valve arrangement of the at least one associated wheel brake;
• a reservoir hydraulically connected to the MC power transmission unit and each of the iso/dump control valve arrangements;
• at least one electric brake motor, each electric brake motor being operative to selectively drive a selected wheel brake;
• a first electronic control unit operative to selectively control the electric motor of the MC power transmission unit;
• a second electronic control unit operative to selectively control the second electric motor, at least one of the iso/dump control valve arrangements, and at least one of the first and second traction control iso valves;
• and
• a third electronic control unit operative to control the at least one electric brake motor,
• the MC power transmission unit having:
• a ball screw,
• a ball nut selectively driven by the ball screw for longitudinal motion relative thereto,
• a primary piston operatively coupled to the ball nut;
• a secondary piston operatively coupled to the primary piston,
• a primary chamber at least partially defined by a surface of the primary piston, the primary chamber being configured to contain hydraulic fluid and selectively pressurized by reciprocal motion of the primary piston driven directly by longitudinal motion of the ball nut,
• a secondary chamber at least partially defined by a face of the secondary piston, a backside of the secondary piston at least partially defining the primary chamber, the secondary chamber being configured to contain hydraulic fluid and selectively pressurized by reciprocal motion of the secondary piston driven indirectly by longitudinal motion of the ball nut,
• a first output channel selectively placing the primary chamber in fluid communication with the first output line,
• a second output channel selectively placing the secondary chamber in fluid communication with the second output line, and
• the first electric motor selectively drives the ball screw to responsively reciprocate at least one of the primary and secondary pistons within a corresponding primary or secondary chamber.