System for diagnosing and controlling high-pressure fuel system for in-cylinder fuel injection engine

A system for controlling an in-cylinder fuel injection engine, wherein a low pressure fuel fed from a low pressure pump is regulated to a predetermined fuel pressure by a low pressure regulator to be fed to a high pressure pump, the pressure of said fuel being raised by said high pressure pump and regulated to a predetermined controlled fuel pressure by a high pressure regulator to feed a high pressure fuel to an injector, and wherein during low engine speeds with low loads, a stratified combustion based on a late injection is selected to set a fuel injection quantity, a fuel injection timing and an ignition timing, which are adapted to the stratified combustion, on the basis of the engine operating condition, and during high engine speeds with high loads, a uniform premixed combustion based on an early injection is selected to set a fuel injection quantity, a fuel injection timing and an ignition timing, which are adapted to the uniform premixed combustion, on the basis of the engine operating condition, said injection quantity of fuel being injected directly into a cylinder by the injector to ignite the injected fuel by a spark plug at said ignition timing to achieve the stratified combustion or the uniform premixed combustion, said system control comprising:

• opening/closing valve means provided in a fuel by-pass passage provided for by-passing said high pressure regulator to establish a communication between a high-pressure fuel system and a low-pressure fuel system;
• diagnosing means for monitoring at least one of the behavior of a fuel pressure of said high-pressure fuel system and the relationship between an air-fuel ratio and a fuel injection pulse width for the injector, said diagnosing means determining that said high-pressure fuel system is abnormal when meeting at least one of conditions that said behavior of the fuel pressure is abnormal and that said air-fuel ratio is incompatible with said fuel injection pulse width;
• opening/closing valve control means for closing said opening/closing valve means when said high-pressure fuel system is normal and for opening said opening/closing valve means when said high-pressure fuel system is abnormal;
• and
• combustion system selecting means for selecting the stratified combustion based on the late injection during low engine speeds with low loads, and the uniform premixed combustion based on the early injection during high engine speeds with high loads, on the basis of the engine operating condition;
• fuel injection control means for setting a fuel injection pulse width for the injector, which defines a fuel injection quantity adapted to the stratified combustion, on the basis of the engine operating condition in accordance with the controlled fuel pressure regulated by said high pressure regulator and for setting a fuel injection timing in a compression stroke of a cylinder to be injected when said high-pressure fuel system is normal and when the stratified combustion is selected, said fuel injection control means setting a fuel injection pulse width for the injector, which is adapted to the uniform premixed combustion, on the basis of the engine operating condition in accordance with the controlled fuel pressure regulated by said high pressure regulator and setting a fuel injection timing in an exhaust stroke end or intake stroke of a cylinder to be injected when said high pressure fuel system is normal and when the uniform premixed combustion is selected, and said fuel injection control means setting a fuel injection pulse width adapted to the uniform premixed combustion on the basis of said engine operating condition in accordance with the pressure of a low pressure fuel regulated by said low pressure regulator and setting a fuel injection timing adapted to the uniform premixed combustion when said high-pressure fuel system is abnormal;
• and
• ignition timing control means for setting an ignition timing adapted to the stratified combustion on the basis of the engine operating condition when said high-pressure fuel system is normal and when the stratified combustion is selected, and for setting an ignition timing adapted to the uniform premixed combustion on the basis of the engine operating condition when said high-pressure fuel system is normal and when the uniform premixed combustion is selected or when said high-pressure fuel system is abnormal.