Patent ID: 6871633
Filing Date: 2005-03-29
Classification: F02D,F02M

Abstract:
1. An abnormality diagnosis apparatus for a high pressure fuel system of a cylinder injection type internal combustion engine, comprising: an accumulator for storing a fuel in a high pressure state; a high pressure fuel pump for taking in the fuel supplied from a fuel tank to thereby feed under pressure said fuel to said accumulator; a spill valve for opening/closing a fuel relief passage which communicates a pressure increasing chamber of said high pressure fuel pump to a low pressure side thereof; injectors for supplying directly through injection into individual cylinders of said internal combustion engine the fuel of high pressure stored in said accumulator; a fuel pressure sensor for detecting as a fuel pressure the pressure of the fuel supplied to said injector; and fuel pressure control means for variably setting a target value of said fuel pressure while setting said fuel pressure to said target value, wherein a control period of said high pressure fuel pump validated by means of said fuel pressure control means includes a fuel intake period for taking in the fuel and a fuel discharge period for discharging the fuel, said fuel discharge period including a spill valve closing control period for close-controlling said spill valve for feeding the fuel under pressure to said accumulator from said pressure increasing chamber, and a spill valve opening control period for open-controlling said spill valve for releasing the fuel to said low pressure side from said pressure increasing chamber, and wherein said fuel pressure control means includes spill valve control period setting means for adjusting said spill valve closing control period and said spill valve opening control period; abnormality decision enable period detecting means for detecting as an abnormality decision enable period said spill valve opening control period with falls within said fuel discharge period in the course of operation of said internal combustion engine; fuel pressure change arithmetic means for arithmetically determining change of said fuel pressure on the basis of said abnormality decision enable period; and abnormality diagnosing means for making decision as to abnormality of said spill valve on the basis of the change of said fuel pressure.