Patent Document ID: 10113500
Application ID: 12766030
Patent Flag: 1

Claim One:
1. A fuel-pressure controller for a direct injection engine having a low-pressure pump and a high-pressure pump, the low-pressure pump pumping up a fuel in a fuel tank and supplying the fuel to the high-pressure pump, the high-pressure pump pressurizing the fuel and discharging a high-pressure fuel toward a fuel injector, the fuel-pressure controller comprising: a low pressure fuel control means for controlling the low-pressure pump in such a manner that a fuel pressure in a low pressure fuel passage agrees with a target low fuel pressure; a pressure regulator returning the fuel in the low pressure fuel to the fuel tank when the fuel pressure in the low pressure fuel passage becomes greater than or equal to a specified value; an open-valve detection sensor detecting that the pressure regulator returns the fuel to the fuel tank; a learning means for executing the low pressure fuel control in a case that a specified learning execution condition is satisfied when the target low fuel pressure is set to the specified value, the learning means for gradually correcting a control amount of the low pressure fuel control so that a fuel pressure in the low pressure fuel passage is increased from a value lower than the specified value, the learning means for learning a control error in the low pressure fuel control based on a correction amount at a time when the open-valve detection sensor detects that the pressure regulator returns the fuel to the fuel tank; and a correction means for correcting the control amount of the low pressure fuel control based on the control error learned by the learning means, wherein the low pressure fuel control means varies the target low fuel pressure within a fuel pressure range which is lower than the specified value according to a driving condition of the engine.