Hydraulic brake apparatus for vehicle

摘要

A hydraulic brake apparatus for a vehicle is provided. The hydraulic brake apparatus includes a master cylinder, a high hydraulic pressure source, a brake assist mechanism, a liquid reservoir, an electronic control device, a hydraulic control device and is configured such that the master cylinder is actuated by a force assisted by the brake assist mechanism to generate a hydraulic pressure and a braking force according to the hydraulic pressure is applied to a wheel of the vehicle. The hydraulic brake apparatus further includes driving pressure reducing valve which is configured such that when a hydraulic pressure in a master pressure input port is higher than that in the driving pressure input port by a predetermined value, the hydraulic brake apparatus is actuated based on the pressure difference to open a hydraulic pressure discharge path extending from a driving hydraulic pressure chamber to the liquid reservoir.

主权项

1. A hydraulic brake apparatus for a vehicle comprising:
a brake assist mechanism which includes a power piston and a driving hydraulic pressure chamber, and which is driven by a hydraulic pressure introduced into the driving hydraulic pressure chamber; a master cylinder which includes a master hydraulic pressure chamber and a master piston, wherein the mater piston is actuated by a force assisted by the brake assist mechanism to generate a hydraulic pressure in the master hydraulic pressure chamber; an electronic control device which is configured to determine whether a braking force control is necessary and output a control command when necessary; a hydraulic control device which includes a power driven pump, and which is configured to apply braking force to a wheel of the vehicle based on the hydraulic pressure of the master cylinder under a control of the electronic control device; a hydraulic pressure source which is configured to supply a hydraulic pressure to the driving hydraulic pressure chamber; a liquid reservoir which has an inner pressure lower than the hydraulic pressure of the hydraulic pressure source; a driving pressure regulating valve mechanism which is configured to respectively switch a communication/interrupting state between the hydraulic pressure source and the driving hydraulic pressure chamber and a communication/interrupting state between the driving hydraulic pressure chamber and the liquid reservoir according to an operation amount of a brake operating member so as to regulate the hydraulic pressure in the driving hydraulic pressure chamber to a value corresponding to the operation amount of the brake operating member; and a driving pressure reducing valve which includes:
a valve body;a master pressure input port which is formed in the valve body and is connected with the master hydraulic pressure chamber;a driving pressure input port which is formed in the valve body and is connected with the driving hydraulic pressure chamber; anda valve main body which receives a hydraulic pressure in the master pressure input port and a hydraulic pressure in the driving pressure input port in opposite directions; wherein the valve main body open and closes a hydraulic pressure discharge path extending from the driving hydraulic pressure chamber to the liquid reservoir, wherein the valve main body opens and closes the hydraulic pressure discharge path at a position between the driving hydraulic pressure chamber and the liquid reservoir; and wherein when the hydraulic pressure in the master pressure input port is higher than the hydraulic pressure in the driving pressure input port by a predetermined value, the valve main body opens the hydraulic pressure discharge path at the position between the driving hydraulic pressure chamber and the liquid reservoir such that the pressure in the driving hydraulic pressure chamber is reduced.