Abstract: An electrically driven type low-pressure fuel pump whose flow rate can be set draws fuel from a fuel tank and discharges it at a prescribed pressure commonly to a low-pressure fuel supply system including intake manifold injectors and a low-pressure delivery pipe and to a high-pressure fuel supply system including in-cylinder injectors, a high-pressure delivery pipe and a high-pressure fuel pump. The discharge flow rate of the low-pressure fuel pump is set based on required supply quantities to the low-pressure fuel supply system and to the high-pressure fuel supply system obtained according to the engine operation conditions. The discharge quantity of the fuel pump in the internal combustion engine can be set as appropriate, and thus, deterioration in fuel efficiency due to excessive flow rate setting and operation failure due to insufficient fuel supply can be prevented, whereby reliability is improved.

Abstract: The engine ECU executes a program including the step of detecting an engine coolant temperature, the step of detecting an engine speed and an engine load, the step of estimating a temperature at a tip end of an in-cylinder injector based on the engine coolant temperature, the engine speed and the engine load, and, when the temperature at the tip end is greater than a guaranteed temperature, the step of calculating a drive duty of a high-pressure fuel pump that ensures a decrease of the temperature at the tip end of the in-cylinder injector to the guaranteed temperature, and the step of controlling the high-pressure fuel pump using the drive duty.

Abstract: A fuel injector for an internal combustion engine including an in-cylinder fuel injection valve and an intake port fuel injection valve. An ECU controls an electromagnetic valve to keep a fuel inlet of a high pressure pump closed during an intake port injection mode during which fuel is injected only from an intake port fuel injection valve. As a result, even if the plunger reciprocates in the high pressure pump, fuel does not flow between the high pressure pump and a low pressure fuel path. Thus, pressure pulsation that would be caused by the operation of the high pressure pump does not occur in low pressure fuel.

Abstract: An ECU calculates the difference between the fuel pressure in a high-pressure distribution pipe and a target pressure when fuel is injected only from an air-intake passage injector. The ECU determines the bulk modulus of fuel that is associated with the coolant temperature. The ECU determines the amount of fuel that is to be discharged from a high-pressure pump based on the pressure difference and the bulk modulus. Then, the ECU actuates the high-pressure pump in accordance with the determined discharge amount.

Abstract: A fuel supply system according to the present invention includes a first delivery pipe for intake passage injection and a second delivery pipe for cylinder injection. The second delivery pipe is provided with a relief valve. A fuel discharge section of the relief valve is connected to the first delivery pipe via a relief passage.

Abstract: An ECU calculates the difference between the fuel pressure in a high-pressure distribution pipe and a target pressure when fuel is injected only from an air-intake passage injector. The ECU determines the bulk modulus of fuel that is associated with the coolant temperature. The ECU determines the amount of fuel that is to be discharged from a high-pressure pump based on the pressure difference and the bulk modulus. Then, the ECU actuates the high-pressure pump in accordance with the determined discharge amount.

Abstract: An ECU for an internal combustion engine predicts change in the driving state of the engine when switching from port injection mode to in-cylinder injection mode. In accordance with the prediction, the ECU actuates a high-pressure pump before entering the in-cylinder injection mode to pressurize the fuel supplied to an air-intake passage injector.

Abstract: A fuel injector for an internal combustion engine including an in-cylinder fuel injection valve and an intake port fuel injection valve. An ECU controls an electromagnetic valve to keep a fuel inlet of a high pressure pump closed during an intake port injection mode during which fuel is injected only from an intake port fuel injection valve. As a result, even if the plunger reciprocates in the high pressure pump, fuel does not flow between the high pressure pump and a low pressure fuel path. Thus, pressure pulsation that would be caused by the operation of the high pressure pump does not occur in low pressure fuel.

Abstract: The amount of fuel ejected from a high-pressure fuel pump that ejects fuel toward a delivery pipe is adjusted by controlling the valve closure start timing of an electromagnetic spill valve. In this manner, the fuel pressure in the delivery pipe is controlled. The duty ratio DT used for controlling the valve closure start timing of the electromagnetic spill valve is calculated based on a valve closure start timing that provides a maximum amount of fuel ejection. The actual fuel ejection characteristic of a high-pressure fuel pump may deviate from a designed state due to individual differences of the pump. However, the valve closure start timing of the electromagnetic spill valve that provides the maximum amount of fuel ejection in accordance with the actual fuel ejection characteristic is learned as a maximum ejection timing. Based on the maximum ejection timing, the duty ratio DT is calculated.

Abstract: The amount of fuel ejected from a high-pressure fuel pump that ejects fuel toward a delivery pipe is adjusted by controlling the valve closure start timing of an electromagnetic spill valve. In this manner, the fuel pressure in the delivery pipe is controlled. The duty ratio DT used for controlling the valve closure start timing of the electromagnetic spill valve is calculated based on a valve closure start timing that provides a maximum amount of fuel ejection. The actual fuel ejection characteristic of a high-pressure fuel pump may deviate from a designed state due to individual differences of the pump. However, the valve closure start timing of the electromagnetic spill valve that provides the maximum amount of fuel ejection in accordance with the actual fuel ejection characteristic is learned as a maximum ejection timing. Based on the maximum ejection timing, the duty ratio DT is calculated.