| 摘要 |
The invention concerns a power braking system for a motor vehicle, comprising a master cylinder provided with a main hydraulic piston (30) for generating an increase in pressure (P1) of the brake fluid, and a pneumatic booster servo motor capable of being controlled by the application of an input force (F2) on a control rod (26) secured to a plunger (28) controlling the opening of a three-way valve (24), the servo motor comprising a rigid outer cover (10) sealingly divided into at least two chambers (12, 14) by a mobile partition (16), capable of being stressed by a difference in pressure between the two chambers (12, 14) resulting from the opening of the three-way valve (24) and of driving a pneumatic piston (22) bearing the three-way valve (24) and contributing at least in transmitting a boost force (F1) to the main hydraulic piston (30) of the master cylinder (200) which itself includes a hollow mobile cylinder (32) and inside which slides, sealingly and along the axial direction, a reaction piston (34) capable of receiving at least the input force (F2). The invention is characterised in that the reaction piston (34) is secured to the plunger (28) and defines in the mobile cylinder (32) a reaction chamber (36) communicating with the internal volume (V) of the master cylinder (200) by means of a pressure equalising device (50, 64).
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