Methods and systems for fixed and variable pressure fuel injection

摘要

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.

主权项

1. A fuel system, comprising:
a first direct injector receiving fuel from a first fuel rail and delivering fuel to an engine cylinder; a second direct injector receiving fuel from a second fuel rail and delivering fuel to the engine cylinder; a high pressure mechanical fuel pump providing fuel at a variable high pressure to the first fuel rail and at a fixed high pressure to the second fuel rail, the high pressure fuel pump including no electrical connection to a controller, the first fuel rail coupled to an outlet of the high pressure fuel pump, the second fuel rail coupled to an inlet of the high pressure fuel pump; a solenoid activated pressure control valve positioned upstream of the inlet of the high pressure fuel pump for varying a pressure of fuel delivered by the pump to the first fuel rail; and a mechanical pressure relief valve coupled upstream of the high pressure fuel pump, between the pressure control valve and the second fuel rail, the pressure relief valve configured to maintain the fixed pressure at the second fuel rail.