Failure diagnosis apparatus of brake system and failure diagnosis method of brake system

Abstract

A failure diagnosis apparatus of brake system includes a determination unit to determine functional normality of an electric vacuum pump based on a detection result of at least one of a booster internal pressure detection unit for detecting internal pressure of a negative pressure chamber of a booster and a current value detection unit for detecting an operating electric current value of the pump and a detection result of a pipe internal pressure detection unit for detecting internal pressure of a pipe communicated with a discharge port of the pump.

1 . A failure diagnosis apparatus of a brake system including:
 a first passage connected to a negative pressure chamber of a brake booster and an intake system of an engine;   a second passage branching off from the first passage;   an electric vacuum pump provided in the second passage;   a first check valve for preventing a fluid from flowing from the intake system to the negative pressure chamber through the second passage; and   a second check valve for preventing the fluid from flowing from the intake system to the negative pressure chamber through the first passage and preventing a fluid from flowing the intake system and a discharge port of the electric vacuum pump toward an suction port of the electric vacuum pump through the first passage; and   a determination unit configured to determine functional normality of the electric vacuum pump based on a detection result of at least one of a booster internal pressure detection unit for detecting internal pressure of the negative pressure chamber and a current value detection unit for detecting an operating electric current value of the electric vacuum pump and a detection result of a pipe internal pressure detection unit for detecting internal pressure of a pipe communicated with the discharge port of the electric vacuum pump.   
     
     
         2 . The failure diagnosis apparatus of a brake system according to  claim 1 ,
 wherein the brake system further includes a changeover unit to change a connection target of the discharge port of the electric vacuum pump to either one of an intake-system-side passage communicated with the first passage and blocked off from atmosphere and an atmosphere-side passage blocked off from the first passage and communicated with atmosphere, and   wherein the pipe internal pressure detection unit is used to detect internal pressure of a pipe between the electric vacuum pump and the changeover unit.   
     
     
         3 . A failure diagnosis method of a brake system including:
 a first passage connected to a negative pressure chamber of a brake booster and an intake system of an engine;   a second passage branching off from the first passage;   an electric vacuum pump provided in the second passage;   a first check valve for preventing a fluid from flowing from the intake system to the negative pressure chamber through the second passage; and   a second check valve for preventing the fluid from flowing from the intake system to the negative pressure chamber through the first passage and preventing a fluid from flowing the intake system and a discharge port of the electric vacuum pump toward an suction port of the electric vacuum pump through the first passage; and   wherein the method includes determining functional normality of the electric vacuum pump based on a detection result of at least one of internal pressure of the negative pressure chamber and an operating electric current value of the electric vacuum pump and a detection result of internal pressure of a pipe communicated with the discharge port of the electric vacuum pump.   
     
     
         4 . The failure diagnosis method of a brake system according to  claim 3 ,
 wherein the brake system further includes a changeover unit to change a connection target of the discharge port of the electric vacuum pump to either one of an intake-system-side passage communicated with the first passage and blocked off from atmosphere and an atmosphere-side passage blocked off from the first passage and communicated with atmosphere, and   wherein the detection result of internal pressure of the pipe communicated with the discharge port of the electric vacuum pump is a detection result of internal pressure of a pipe between the electric vacuum pump and the changeover unit.