FUEL INJECTION DEVICE FOR INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To solve such problems that abnormal fuel pressure results from impossibility to fully discharge fuel in a common rail and that excess fuel pressure drop and not intended engine stall result from excessive fuel discharge the other way around if an electric control relief valve and a mechanical relief valve are not cooperatively controlled well when a method compensating flow rate shortage by the mechanical relief valve is employed in a structure in which flow rate of the electric control relief valve is short with respect to whole delivery flow rate of a high pressure fuel pump.

SOLUTION: In a high pressure fuel system including the mechanical relief valve and the electric control relief valve, operation of the electric control relief valve is started after pressure reaches the value at which the mechanical relief valve starts operation or higher so as to make the mechanical relief valve sufficiently operate at full delivery of the high pressure fuel pump. Discharge is done by using both of the mechanical relief valve and the electric control relief valve thereby. Flow rate of the electric control relief valve is controlled based on pressure characteristics of a case that only the mechanical relief valve is operated in full delivery of the high pressure fuel pump during operation of the electric control relief valve.

COPYRIGHT: (C)2011,JPO&INPIT