| 摘要 |
<p>1. Brake booster comprising a housing (1), a piston structure (4) dividing the housing internally into two chambers (5, 6), a distribution valve means arranged in a valve body (8) integral with the piston structure (4) and actuable by means of an input member (16) to generate a pressure differential selectively between the chambers, the valve means comprising a plunger (114) mounted axially slideably in a central bore (15) of the valve body (8) and connected to the input member (16), the plunger having at least one first peripheral shoulder (21) and defining, at one of its ends, a first flap seat (12), and a second flap seat (13) formed in the valve body (8) concentrically relative to the first flap seat (12), and a flap means (11) mounted in the valve body and stressed elastically towards the first and second flap seats, a restoring spring (17) bearing in the valve body and stressing the input member (16) in the opposite direction to the flap seats, and means of positioning the plunger which are arranged in the valve body and which interact with the plunger to assign to it at least two separate specific positions relative to the valve body, characterized in that the positioning means consist of the combination of a first positioning member (23) fastened in the valve body (8) and having an inner end (26) capable of interacting with a first zone of the first shoulder (21) of the plunger (14), to position the latter in a specific position of retraction relative to the valve body (8), and of a second positioning member (30; 30') mounted pivotally in the valve body (8) and having a first portion (29; 29') capable of interacting with a second zone of the first shoulder (21) of the plunger, and a second portion (31; 31') capable of interacting, in the vicinity of the position of rest of the booster, with a stationary element (9; 10) connected to the housing (1), in order, at least in this position of rest, to place the second positioning the plunger (14), via its first portion (29; 29'), in a specific position of rest relative to the valve body (8).</p> |
