Vehicle brake system with secondary brake module

A brake system having first and second wheel brakes and being operable under a non-failure normal braking mode and a manual push-through mode, the system comprising:

• a master cylinder operable by a brake pedal during the manual push-through mode, wherein the master cylinder includes
• a master cylinder housing defining a bore,
• a first piston slidably disposed in the bore, and wherein the first piston is operable during the manual push-through mode to pressurize a first pressure chamber providing fluid flow at a first output for actuating the first wheel brake, and
• a second piston slidably disposed in the bore, and wherein the second piston is operable during the manual push-through mode to pressurize a second pressure chamber providing fluid flow at a second output for actuating the second wheel brake;
• a pedal simulator in selective fluid communication with the master cylinder;
• a simulator valve selectively permitting fluid communication between the master cylinder and the pedal simulator;
• a first plunger assembly providing fluid pressure for actuating the first and second wheel brakes under the normal braking mode;
• and
• a secondary brake module (“SBM”) including
• a second plunger assembly for generating brake actuating pressure in a SBM pressure chamber for actuating the first and second wheel brakes under the manual push-through mode, wherein the SBM pressure chamber of the plunger assembly is in fluid communication with the first pressure chamber of the master cylinder such that an increase in pressure within the SBM pressure chamber of the plunger assembly, via forward movement of an SBM piston within the secondary brake module, causes an increase in pressure within the first and second pressure chambers of the master cylinder and such that a decrease in pressure within the SBM pressure chamber of the plunger assembly, via a rearward movement of the SBM piston within the secondary brake module, causes a decrease in pressure within the first and second pressure chambers of the master cylinder when the brake pedal is released,
• a pressure sensor for sensing the pressure within the pressure chamber of the second plunger assembly, and
• a single fluid conduit connecting the SBM pressure chamber of the second plunger assembly with a remaining portion of the brake system;
• a first electronic control unit for controlling the first source of pressurized fluid disposed in a primary brake module;
• and
• a second electronic control unit, separate from the first electronic control unit, for controlling the secondary brake module, and wherein the second electronic control unit is connected with the pressure sensor of the secondary brake module.