Brake stroke simulator and a vehicle hydraulic brake apparatus provided with the same

A vehicle hydraulic brake apparatus comprising:

• a wheel cylinder operatively mounted on a vehicle wheel for applying a brake force to the vehicle wheel;
• a master cylinder operatively connected to a brake pedal for generating master cylinder hydraulic pressure in response to an operational force applied to the brake pedal;
• a hydraulic pressure generating device different from the master cylinder;
• a hydraulic pressure control valve disposed between the hydraulic pressure generating device and the wheel cylinder for adjusting brake hydraulic pressure of the wheel cylinder by applying hydraulic pressure outputted from the hydraulic pressure generating device;
• a first opening and closing valve for selectively connecting and disconnecting the master cylinder and the wheel cylinder;
• a brake stroke simulator operatively connected to the master cylinder to provide a brake pedal operational feeling with the first opening and closing valve under a closed condition;
• a second opening and closing valve for selectively connecting and disconnecting the master cylinder and the brake stroke simulator;
• a brake operating amount detecting means for detecting an operational amount of the brake pedal;
• and
• control means for closing the first opening and closing valve and opening the second opening and closing valve during operation of the hydraulic pressure generating device, and for controlling the hydraulic pressure control valve in response to an output detected by the brake operating amount detecting means;
• the brake stroke simulator comprising:
• a housing;
• a first movable member freely slidably disposed in the housing in a fluid-tight manner and defining a hydraulic pressure chamber in the housing at one side of the first movable member which is adapted to receive hydraulic pressure corresponding to the operational force applied to the brake operating member;
• a second movable member disposed in the housing at an opposite side of the first movable member and movable together with the first movable member in response to sliding movement of the first movable member in a direction for increasing a volume of the hydraulic pressure chamber;
• a first spring biasing the first movable member in a direction for reducing the volume of the hydraulic pressure chamber;
• a second spring biasing the second movable member in said direction, the first and second springs having different spring constants;
• and
• a shock absorbing elastic member compressed by the first movable member upon sliding movement of the first movable member at a predetermined stroke against the biasing force of the first spring and compressed by the second movable member upon sliding movement of the second movable member at a predetermined stroke against the biasing force of the second spring.