A decoupling element for a fuel-injection device has a low-noise and pivotable construction. The fuel-injection device includes at least a fuel injector and a receiving bore in a cylinder head for the fuel injector as well as the decoupling element between a valve housing of the fuel injector and a wall of the receiving bore. The decoupling element is in the form of a ring, in particular a closed ring, which has a lower end face that sits on a shoulder of the receiving bore, and which has an upper end face that rises conically from radially outside toward radially inside and is in intimate contact with a spherically curved shoulder area of the valve housing of the fuel injector. The fuel-injection device is particularly suitable for the direct injection of fuel into a combustion chamber of a mixture-compressing combustion engine having externally supplied ignition.

A method for operating an internal combustion engine having a high-pressure fuel injection system stops and starts the engine independently of an intervention by the motor vehicle operator and then restarted. A high-pressure fuel pump is used to pump fuel to a high-pressure reservoir to which at least one high-pressure fuel injector is connected in order to inject fuel into the at least one cylinder of the internal combustion engine. Fuel pressure can be adjusted on the high-pressure side using an electrically actuated pressure reduction valve (PDV).

A decoupling element for a fuel-injection device has a low-noise and pivotable construction. The fuel-injection device includes at least a fuel injector and a receiving bore in a cylinder head for the fuel injector as well as the decoupling element between a valve housing of the fuel injector and a wall of the receiving bore. The decoupling element is in the form of a ring, in particular a closed ring, which has a lower end face that sits on a shoulder of the receiving bore, and which has an upper end face that rises conically from radially outside toward radially inside and is in intimate contact with a spherically curved shoulder area of the valve housing of the fuel injector. The fuel-injection device is particularly suitable for the direct injection of fuel into a combustion chamber of a mixture-compressing combustion engine having externally supplied ignition.

An object is to suppress cavitation generated at a distal end portion of a seat face when a valve body and a seat portion collide with each other. In a relief valve of a fuel pump, an intersection between the seat face and a flow channel hole is formed at a position more distant than the seat portion formed of the valve body in a valve closing state and the seat face in order to suppress generation of cavitation bubbles when the valve body improves and releases high-pressure fuel.

A method for operating an internal combustion engine having a high-pressure fuel injection system stops and starts the engine independently of an intervention by the motor vehicle operator and then restarted. A high-pressure fuel pump is used to pump fuel to a high-pressure reservoir to which at least one high-pressure fuel injector is connected in order to inject fuel into the at least one cylinder of the internal combustion engine. Fuel pressure can be adjusted on the high-pressure side using an electrically actuated pressure reduction valve (PDV).

An object is to suppress cavitation generated at a distal end portion of a seat face when a valve body and a seat portion collide with each other. In a relief valve of a fuel pump, an intersection between the seat face and a flow channel hole is formed at a position more distant than the seat portion formed of the valve body in a valve closing state and the seat face in order to suppress generation of cavitation bubbles when the valve body improves and releases high-pressure fuel.