Negative pressure type booster device

Abstract

In the negative pressure booster device, one second passage communicated directly with atmosphere is formed between the inner surface of the sliding column of the valve piston and the outer surface of the silencer, and one communication unit is set for the control to alter the passage area based the forward amount of the input rod when the input rod goes forward and exceeds the preset distance relative to the valve piston. Therefore, when the brake pedal is treaded, atmosphere air may pass through the communication unit and the second passage to the variable pressure cavity, and this can raise the response characteristic of the braking operation based on the treading mode.

Description

technical field [0001] The present invention relates to a negative pressure booster device for vehicles, in particular to a negative pressure booster device capable of high response when the brake pedal is stepped on hard. Background technique [0002] Generally, in a negative pressure booster device, when the brake pedal is stepped on to advance the input rod, and thus advance the plunger relative to the valve piston, the negative pressure valve is in contact with the negative pressure valve seat so as to block the pressure in the variable pressure chamber. The communication between the chamber and the constant pressure chamber. As the plunger advances further, the atmospheric valve seat disengages from the atmospheric valve, directing atmospheric air from the surrounding atmosphere through the muffler and filter element to the variable pressure chamber. Therefore, the valve piston moves forward according to the pressure difference between the variable pressure chamber and...

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Problems solved by technology

However, since there is no muffler arranged in the additional air passage for the rapid entry of atmospheric air, the throttling noise is likely to Leakage

[0007] Furthermore, in the device of the aforementioned patent, since the relative displacement between the sleeve and the valve member slightly increases after opening the valve member causing a sharp increase in output power, the responsiveness exhibits two modes of operation, including the normal operation state and the response There is a problem that the responsiveness characteristic of the booster that changes according to the depression state of the brake pedal cannot be obtained.

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