Control System and Method for Isolating High Pressure Pilot Fuel in Dual-Fuel HPDI System

摘要

An improved fuel system for a dual-fuel internal combustion engine. During normal operation, the primary fuel passes through a pressure regulator before arriving at a primary fuel rail. Further, pressurized secondary fuel is delivered to both a secondary fuel rail and to the pressure regulator for purposes of regulating the output pressure of the primary fuel that is delivered to the primary fuel rail. When the pressure at the primary fuel supply or between the primary fuel supply and the pressure regulator drops below a minimum operating pressure, the pressure regulator is isolated from the secondary fuel and the secondary fuel continues to be pressurized until it reaches a suitable pressure for operating in a limp mode. Then, the secondary fuel, which is pressurized to greater than a normal operating pressure, may be injected at the higher pressure for improved performance of the engine in the limp mode.

主权项

1. A fuel system for an internal combustion engine, the fuel system comprising:
a primary fuel supply in communication with a primary chamber of a pressure regulator, the primary chamber of the pressure regulator in communication with a primary fuel rail, the primary fuel supply in communication with a primary pressure sensor, the primary pressure sensor linked to a controller, a secondary fuel supply in communication with a secondary fuel pump, the secondary fuel pump in communication with a secondary fuel isolation valve and a secondary fuel rail, the secondary fuel pump linked to the controller, the secondary fuel pump in communication with a secondary pressure sensor disposed downstream of the secondary fuel pump, the secondary fuel isolation valve in selective communication with a secondary chamber of the pressure regulator, the secondary fuel isolation valve linked to the controller, the secondary fuel isolation valve having a normal operating position where the secondary fuel pump is in communication with the secondary chamber through the secondary fuel isolation valve, the secondary fuel isolation valve also having a limp mode position where the secondary fuel isolation valve isolates the secondary fuel pump from the secondary chamber, wherein the controller is configured to command the secondary fuel pump to deliver secondary fuel to the secondary fuel isolation valve and the secondary fuel rail at a first pressure and to shift the secondary fuel isolation valve to its normal operating position when the primary pressure sensor detects that a pressure of the primary fuel supply is above a predetermined minimum operating pressure, and wherein the controller is configured to command the secondary fuel pump to deliver secondary fuel to the secondary fuel rail at a second pressure and to shift the secondary fuel isolation valve to its limp mode position when the primary pressure sensor detects that the pressure of the primary fuel supply is below the predetermined minimum operating pressure, the second pressure of the secondary fuel rail being greater than the first pressure.