Braking control system comprising a force-control simulator

Brake control system for a motor vehicle comprising a brake pedal (1), a brake booster (4) which comprises a front chamber (40) and a rear chamber (41) which are separated by a booster piston (42), said booster (4) supplying an amplified braking command dependent on the pressure difference between the two said chambers, a brake master cylinder (5) receiving the amplified braking commands from the brake booster (4), characterized in that it comprises a simulator (3) coupled pneumatically or hydraulically to the piston (42) of the brake booster (4), said simulator (3) receiving at least one braking command from the brake pedal (1) and in return establishing or controlling a pressure difference between the front chamber (40) and the rear chamber (41) of the brake booster so as to control the movement of the piston (42), characterized in that it comprises a pneumatic servomotor for controlling a pneumatic brake booster or brake servo, characterized in that said control servomotor comprises a space (8) comprising a first bore (89) in which there slides a three-way valve piston (30) equipped with a three-way valve capable of:

• placing the rear chamber (41) in communication with the front chamber (40);
• or of isolating the rear chamber (41) from the front chamber (40);
• or of placing the rear chamber (41) in communication with a pressure source that establishes a pressure difference between the front chamber and the rear chamber, characterized in that a first region (89A) of the first bore (89) lying on one side of the three-way valve piston (30) is substantially at the same pressure as the front chamber, and in that a second region (89B) of this bore (89), lying on the opposite side of the rear chamber (41) to the three-way valve piston (30) is substantially at the same pressure as the rear chamber, characterized in that said space (8) has a first end lying in the rear chamber (41) of the booster, near to said booster piston (42), and a second end lying on the opposite side of the booster wall (46) to the side to which the brake master cylinder is attached, and in that the first region (89A) of the first bore (89) lies between said three-way valve piston (30) and the first end, while the second region (89B) of the first bore (89) lies between the three-way valve piston (30) and the second end, characterized in that said space (8) is held against the rear wall (46) of the brake booster by a retaining spring (323) and by the pressure obtaining in the brake master cylinder when the axial force exerted on the control piston (34) is below a threshold value, and in that it can move axially when this force exceeds this threshold value.

Brake control system for a motor vehicle comprising a brake pedal (1), a brake booster (4) which comprises a front chamber (40) and a rear chamber (41) which are separated by a booster piston (42), said booster (4) supplying an amplified braking command dependent on the pressure difference between the two said chambers, a brake master cylinder (5) receiving the amplified braking commands from the brake booster (4), characterized in that it comprises a simulator (3) coupled pneumatically or hydraulically to the piston (42) of the brake booster (4), said simulator (3) receiving at least one braking command from the brake pedal (1) and in return establishing or controlling a pressure difference between the front chamber (40) and the rear chamber (41) of the brake booster so as to control the movement of the piston (42), characterized in that it comprises a pneumatic servomotor for controlling a pneumatic brake booster or brake servo, characterized in that said control servomotor comprises a space (8) comprising a first bore (89) in which there slides a three-way valve piston (30) equipped with a three-way valve capable of:

• placing the rear chamber (41) in communication with the front chamber (40);
• or of isolating the rear chamber (41) from the front chamber (40);
• or of placing the rear chamber (41) in communication with a pressure source that establishes a pressure difference between the front chamber and the rear chamber, characterized in that the three-way valve comprises:
• a valve body (30) having a first valve seat (309),
• a valve shutter (303) capable of moving axially and intended, by pressing against the first valve seat (309), to close off a first passage of the three-way valve and thus isolate the front (40) and rear (41) chambers from one another,
• an axially movable sensor (302) having a second valve seat intended to press against the valve shutter (303) and to open a second passage between the rear chamber and a source of raised pressure by moving away from the valve shutter (303), characterized in that said space (8) comprises a second bore (31) situated on the same side as the first end of the chamber (8) and in which there slides a control piston (34) which is controlled by the brake pedal (1) and which controls the axial movement of the sensor (302) of the three-way valve, this second bore also comprising an elastic element (310) which offers elastic resistance to the movement of the control piston (34), characterized in that the second bore (31) contains a fluid, characterized in that the second bore is supplied with fluid from a brake fluid reservoir.