Bi-modal air assist injection system

A bimodal air-assist fuel injection system for an internal combustion engine comprising:

• a primary air passage including a throttle valve for controlling a volume of air passing therethrough and an idle air duct bypassing said throttle valve;
• an idle air pintle disposed in said idle air duct for controlling a volume of air passing therethrough;
• a secondary air passage for directing assist air to at least one fuel injector tip;
• an air assist solenoid variable between an open mode to permit air flow therethrough and a closed mode to prevent air flow therethrough disposed on said secondary air passage;
• a plurality of shrouds including at least one passage therein interconnecting a plurality of fuel injectors and said secondary air passageway;
• an air bypass circuit coupled at a first end upstream of said air assist solenoid and coupled at a second end downstream of said air assist solenoid to provide an alternate air channel independent of said air assist solenoid to said plurality of fuel injectors;
• an engine controller electronically communicating with said air assist solenoid for varying said air assist solenoid between said open mode and said closed mode;
• an idle air control motor electronically communicating with said engine controller for varying a volume of idle speed control air introduced at a throttle housing;
• and
• a coolant temperature sensor electronically communicating with said engine controller for prompting said engine controller to vary said air assist solenoid between said open mode and said closed mode, said variation to said open mode including ramping up a pulse width modulated signal sent to said air assist valve by a calibrated percentage of duty cycle as a function of a predetermined amount of time to controllably move said air assist valve from said closed mode to said open mode and ramping out a position of said idle air pintle a preselected number of position steps of offset over a second predetermined amount of time to compensate for an additional volume of air passing through said secondary air passage, and said variation to said closed mode including ramping out said pulse width modulated signal sent to said air assist valve by a second calibrated percentage of duty cycle as a function of a third predetermined amount of time to controllably move said air assist valve from said open mode to said closed mode and ramping in said position of said idle air pintle a second preselected number of position steps of offset over a fourth predetermined amount of time to compensate for a reduced volume of air passing through said secondary air passage.

A method of controlling air flow in an internal combustion engine comprising:

• detecting a coolant temperature;
• converting a secondary air passage communicating with a plurality of fuel injectors to an open mode by varying a volume of air permitted to flow through a solenoid disposed on said secondary air passage a calibrated amount over a preselected period of time if said coolant temperature is less than or equal to a predetermined temperature;
• said variation to said open mode including ramping up a pulse width modulated signal sent to said air assist valve by a calibrated percentage of duty cycle as a function of a predetermined amount of time to controllably move said air assist valve from said closed mode to said open mode and ramping out a position of said idle air pintle a preselected number of position steps of offset over a second predetermined amount of time to compensate for an additional volume of air passing through said secondary air passage;
• converting said secondary passage to a closed mode by varying a volume of air permitted to flow through said solenoid disposed on said secondary air passage a predetermined amount over a second calibrated period of time if said coolant temperature is greater than a given temperature;
• said variation to said closed mode including ramping out said pulse width modulated signal sent to said air assist valve by a second calibrated percentage of duty cycle as a function of a third predetermined amount of time to controllably move said air assist valve from said open mode to said closed mode and ramping in said position of said idle air pintle a second preselected number of position steps of offset over a fourth predetermined amount of time to compensate for a reduced volume of air passing through said secondary air passage;
• and
• adjusting a volume of air permitted to pass through a throttle housing bypass disposed on a primary air passage communicating with at least one combustion chamber a known amount over a third calibrated period of time when said secondary air passage is converted to one of said open and closed modes.