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 pump 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;
- first and second accumulator assemblies, with each accumulator assembly including
- a medium pressure accumulator, including
- an MPA cavity including at least one brake-side passage adjacent a first end thereof and including at least one pump-side passage adjacent the first end thereof,
- an MPA piston for reciprocal longitudinal motion within the MPA cavity responsive to a predetermined amount of hydraulic fluid flow through at least one of the pump-side passage and the brake-side passage, and
- an MPA biasing spring for urging the MPA piston toward the first end of the MPA cavity;
- a nonpowered MPA fill valve interposed fluidically between the pump-side passage of the MPA cavity and a source of pressurized hydraulic fluid;
- and
- a powered MPA one-way valve interposed fluidically between the brake-side passage of the MPA cavity and the at least one corresponding wheel brake, the MPA one-way valve being a powered solenoid valve including
- a valve cavity placing an input port, configured to accept hydraulic fluid from the brake-side passage of the MPA cavity, and an output port, configured to supply hydraulic fluid to the at least one corresponding wheel brake, in selective fluid communication via a one-way valve fluid path,
- a valve seat located along the one-way valve fluid path and at least partially defined by an interior wall of the valve cavity, and
- a valve poppet configured for reciprocal motion between a poppet open position and a poppet closed position wherein, when the valve poppet is in the poppet closed position, a valve poppet shoulder selectively contacts the valve seat to substantially occlude fluid flow therepast along the one-way valve fluid path, the valve poppet having a valve poppet body,
- wherein the valve poppet shoulder includes a resilient annular seal contained within a sealing groove extending circumferentially around the valve poppet shoulder, the sealing groove being cooperatively defined at least partially longitudinally between a distal valve poppet flange of the valve poppet body and an annular poppet collar;
- and
- an electronic control unit for controlling at least one of the secondary brake module and the master cylinder responsive to at least one braking signal.