JPS61163769U - - Google Patents

Description

[Brief explanation of drawings]

FIG. 1 is a front sectional view of a hydraulic brake booster that is an embodiment of the present invention, and is also a system diagram showing a hydraulic brake system equipped with the hydraulic brake booster. FIG. 2 is an enlarged front sectional view of the hydraulic brake booster, and FIG. 3 is a graph showing its boosting characteristics. FIG. 4 is a front sectional view showing a hydraulic brake booster according to another embodiment of the present invention. FIG. 5 is a front sectional view showing a hydraulic brake booster according to yet another embodiment of the present invention, and FIG. 6 is a graph for explaining its operation. 10: Master cylinder, 40: Booster (hydraulic brake booster), 50: Housing, 52
: Piston (output piston), 56: Piston (
input piston), 58: hydraulic pressure chamber (first hydraulic pressure chamber),
60: Hydraulic pressure chamber (second hydraulic pressure chamber), 62: Valve, 80
: Switching valve, 82...Liquid passage (first liquid passage), 84:
Control valve, 86: Valve element, 88: Valve piston, 9
0: Back pressure chamber, 98: Liquid passage (second liquid passage), 10
0: Electromagnetic on-off valve (electromagnetic valve), 108: Solenoid, 110: Damper, 120: Control device, 122:
Load cell, 124: Vehicle speed detection head, 150:
Switching valve, 152, 154: Valve seat, 156, 158
: Valve, 170: Electromagnetic hydraulic control valve (electromagnetic valve), 1
72: Solenoid.

Claims (1)

[Claims for Utility Model Registration] (1) The input piston and the output piston are fluid-tightly and slidably fitted in the housing to form a first hydraulic chamber between the two pistons, and A switching valve is provided for switching the first hydraulic pressure chamber into at least two states, a state in which the first hydraulic pressure chamber is communicated with the hydraulic pressure source and a state in which the first hydraulic pressure chamber is communicated with the tank, according to the relative movement;
A hydraulic brake booster that doubles the operating force input from the brake operating member to the input piston with the aid of hydraulic pressure in the first hydraulic pressure chamber and outputs it from the output piston, the input piston and the housing a second hydraulic pressure chamber formed between the first hydraulic pressure chamber and the second hydraulic pressure chamber, which communicates with the first hydraulic pressure chamber through a first liquid passage and applies hydraulic pressure to the input piston in the same direction as the operating force; and a first pressure receiving surface. receives the liquid pressure in the first liquid passage, and receives the liquid pressure in the back pressure chamber on the second pressure receiving surface opposite to the first pressure receiving surface, so that the liquid pressure in the first liquid passage is applied to the liquid in the back pressure chamber. a control valve that controls the hydraulic pressure in the second hydraulic pressure chamber to be lower than the hydraulic pressure in the first hydraulic pressure chamber by including a valve piston that shuts off the first liquid passage when the pressure is overcome; and the back pressure chamber; a solenoid valve provided in a second liquid passage connecting the first liquid pressure chamber or the liquid pressure source and controlling the liquid pressure in the back pressure chamber by controlling the current supplied to the solenoid; A hydraulic brake booster characterized in that boost characteristics can be changed by controlling a solenoid valve. (2) the second liquid passage connects the back pressure chamber and the first hydraulic pressure chamber, and the solenoid valve connects the second liquid passage according to supply/stop of electric current; The hydraulic brake booster according to claim 1, which is an electromagnetic on-off valve that shuts off. (3) The solenoid valve is an electromagnetic hydraulic pressure control valve that selectively communicates the back pressure chamber with the tank and the first hydraulic pressure chamber or a hydraulic pressure source to control the hydraulic pressure of the back pressure chamber. A hydraulic brake booster according to claim 1 of the utility model registration claim.