Brake systems with motor-driven master cylinders and bypass valves

A brake system for actuating a plurality of wheel brakes comprising first and second pairs of wheel brakes, the system comprising:

• a reservoir;
• a motor-driven master cylinder operable during a normal non-failure braking mode by actuation of an electric motor of the master cylinder to generate brake actuating pressure at first and second MC outputs for hydraulically actuating the first and second pairs of wheel brakes, respectively;
• a secondary brake module configured for selectively providing pressurized hydraulic fluid at first and second pump outputs for actuating the first and second pairs of wheel brakes in at least one of a normal non-failure braking mode and a backup braking mode, the secondary brake module including an electric PTU motor configured to selectively pressurize the hydraulic fluid by transmitting rotary motion to at least two pump pistons, each pump piston providing pressurized hydraulic fluid to a corresponding one of the first and second pump outputs, each of the first and second pump outputs providing fluid to a corresponding one of the first and second pairs of wheel brakes;
• a first traction control iso valve hydraulically interposed between the motor-driven master cylinder and the first pair of wheel brakes via the first MC output;
• a second traction control iso valve hydraulically interposed between the motor-driven master cylinder and the second pair of wheel brakes via the second MC output;
• a first bypass iso valve hydraulically interposed between the first traction control iso valve and a front brake of the first pair of wheel brakes;
• a second bypass iso valve hydraulically interposed between the second traction control iso valve and a front brake of the second pair of wheel brakes;
• and
• an electronic control unit for controlling at least one of the secondary brake module and the master cylinder responsive to at least one brake pressure signal.