Patent ID: 6889666

Claim:
A fuel pressure control apparatus for a cylinder injection type internal combustion engine, comprising: fuel injection valves for injecting fuel directly into combustion chambers of individual cylinders, respectively, of said internal combustion engine; a fuel rail connected to said fuel injection valves for containing the fuel of a high pressure; a fuel pressure sensor for detecting the pressure of said fuel contained within said fuel rail as a fuel pressure; an intake air temperature sensor for detecting a temperature of intake air of said internal combustion engine or alternatively an ambient temperature thereof as an intake air temperature; a water temperature sensor for detecting a temperature of cooling water of said internal combustion engine as a water temperature; a high pressure fuel pump for supplying said fuel of high pressure to said fuel rail; fuel pressure control means for variably controlling said fuel pressure so that said fuel pressure coincides with a desired fuel pressure which conforms to an operation state of said internal combustion engine; and fuel pressure increase estimating means for estimating an increment of said fuel pressure after stoppage of operation of said internal combustion engine on the basis of said intake air temperature and said water temperature detected during operation of said internal combustion engine, wherein said fuel pressure control means includes desired fuel pressure limiting means for limiting a maximum value of said desired fuel pressure so that a sum value of said desired fuel pressure and said increment of said fuel pressure does not exceed a critical actuation pressure of the fuel injection valve beyond which a failure of fuel injection may occur.