Methods and systems for fixed and variable pressure fuel injection

Abstract

Methods and systems are provided for operating a high pressure injection pump to provide each of high fixed fuel pressure at a first direct injection fuel rail and high variable fuel pressure at a second direct injection fuel rail. The direct injection fuel rail pressure can be raised above a pressure provided with a lift pump via a fuel system configuration that includes various check valves, pressure relief valves, and a spill valve positioned between an inlet of the high pressure injection pump and the port injection fuel rail. Fixed and variable high pressure direct injection may be advantageously used to provide learn the ballistic region of each direct injector.

Description

technical field [0001] The present description relates to systems and methods for adjusting the operation of fuel injectors of an internal combustion engine. These methods may be particularly applicable to engines including fixed high pressure direct fuel injectors and variable high pressure direct fuel injectors. Background technique [0002] Direct fuel injection (DI) systems offer several advantages over port fuel injection systems. For example, direct fuel injection systems can improve cylinder charge cooling so that engine cylinders can be operated at higher compression ratios without incurring adverse engine knock. However, at higher engine speeds and loads, direct fuel injectors cannot deliver the desired amount of fuel to the cylinders because the amount of time the cylinder takes to stroke is shortened, leaving insufficient time to inject the desired amount of fuel. Therefore, at higher engine speeds and loads, the engine may produce less power than desired. Addi...

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Problems solved by technology

Also, at very low pulse widths, the injector may not even open

These operating conditions can lead to large fuel supply errors

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