Patent ID: 9545904
Date: 2017-01-17
CPC Classifications: B60T

Claim:
1. A braking control device for a vehicle adapted to a vehicle brake device comprising: a master cylinder having an input piston which is slidable in a cylinder portion in cooperation with an operation of a brake operating member and an output piston which is slidable in the cylinder portion by contacting with or separating from the input piston by the operation of the brake operating member; a driving hydraulic pressure adjusting device connected to a driving hydraulic pressure chamber formed in the master cylinder for adjusting a driving hydraulic pressure in the driving hydraulic pressure chamber so as not to exceed a predetermined assisting limit hydraulic pressure wherein a master hydraulic pressure in a master hydraulic pressure chamber formed in the master cylinder varies when the output piston slidably moves within the cylinder portion by the driving hydraulic pressure under a state that the input piston is separated from the output piston and the master hydraulic pressure varies when the input piston and the output piston slidably move within the cylinder portion in cooperation with the operation of the brake operating member under a state that both input and output pistons are in contact with each other and wherein the driving hydraulic pressure adjusting device is controlled to adjust the driving hydraulic pressure so that the output piston is separated from the input piston when the driving hydraulic pressure is below the predetermined assisting limit hydraulic pressure; a brake operating amount detecting portion for detecting an operating amount of the brake operating member; and a driving hydraulic pressure control means for performing an ineffective operating amount reducing servo performance which controls the driving hydraulic pressure by the driving hydraulic pressure adjusting device based on a first servo performance which is a predetermined value of an increased amount of the driving hydraulic pressure relative to an increased amount of a brake operating amount when the brake operating amount which is the operating amount of the brake operating member detected by the brake operating amount detecting means is below a predetermined servo performance change operating amount and controls the driving hydraulic pressure by the driving hydraulic pressure adjusting device based on a second servo performance in which the increased amount of the driving hydraulic pressure relative to the increased amount of the brake operating amount is smaller than the first servo performance, until the driving hydraulic pressure becomes the predetermined assisting limit hydraulic pressure before the input piston is brought into contact with the output piston when the brake operating amount is equal to or more than the servo performance change operating amount, so as to reduce an ineffective operating amount which is an increase of the operating amount of the brake operating member from a point where the driving hydraulic pressure reaches the predetermined assisting limit hydraulic pressure to a contact brake operating amount where the input piston is brought into contact with the output piston in the ineffective operating amount reducing servo performance, wherein the servo performance change operating amount is a smaller operating amount than an assisting limit operating amount, wherein the assisting limit operating amount is a braking operating amount of the brake operating member at which the driving hydraulic pressure becomes the predetermined assisting limit hydraulic pressure if the driving hydraulic pressure is controlled based on the first servo performance without changing to the second servo performance at the servo performance change operating amount.