Brake apparatus using electric booster and control method thereof

Abstract

A brake apparatus using an electric booster may include: an electric booster connected to a master cylinder and configured to pressure a push rod by pressurizing a reaction disk using an electromotive force of a motor with a pedal stepping force of a driver who steps on a brake pedal, and pressurize a piston of the master cylinder through the push rod; and a control unit configured to compare required brake pressure by the pedal stepping force of the driver and current brake pressure by the motor control to set pressure, and perform cooperation control through an ESC (Electronic Stability Control) and cooperation control through the electric booster.

What is claimed is: 
     
         1 . A brake apparatus using an electric booster, comprising:
 an electric booster connected to a master cylinder and configured to pressure a push rod by pressurizing a reaction disk using an electromotive force of a motor with a pedal stepping force of a driver who steps on a brake pedal, and pressurize a piston of the master cylinder through the push rod,   wherein the reaction disk has such stiffness that a pedal force, which is varied according to deformations in a central portion and an edge portion of the reaction disk by a change in pedal stepping force of the driver who pressurizes the central portion of the reaction disk through the operating rod and a change in electromotive force of the motor which pressurizes the edge portion of the reaction disk through a bolt screw, and a pedal force which is varied according to a change in brake pressure offset each other.   
     
     
         2 . The brake apparatus of  claim 1 , wherein the reaction disk has such hardness and stiffness that a force of less 3 kgf is required to pressurize the reaction disk when only the central portion is pressurized only by the driver's force and compressed by 1 mm. 
     
     
         3 . The brake apparatus of  claim 1 , wherein the reaction disk has a thickness of at least 10 mm or more. 
     
     
         4 . The brake apparatus of  claim 1 , wherein the reaction disk has stiffness that satisfies the following equation: 
       
         
           
             
               
                 C 
                 1 
               
               < 
               
                 
                   
                     C 
                     5 
                   
                   a 
                 
                 + 
                 
                   
                     C 
                     2 
                   
                   × 
                   
                     C 
                     4 
                   
                   × 
                   
                     C 
                     5 
                   
                 
               
             
           
         
         where C 1  represents the stiffness of the reaction disk, C 2  represents the reciprocal of (booster reaction ratio×pedal ratio), C 4  represents the cross-sectional area of the master cylinder, C 5  represents a change in pressure value depending on a piston displacement difference of 1 mm based on a required amount of liquid, and a represents a pressure change during the regenerative brake cooperation control.