Gas fuel injection valve and fuel injection system

A gas fuel injection valve that is configured to inject a gas fuel, the gas fuel injection valve comprising:

• a main body that has:
• a fuel passage which is configured to conduct the gas fuel;
• and
• an injection hole which is configured to inject the gas fuel received in the fuel passage;
• a valve element that is configured to open and close the injection hole;
• a spring member that is configured to urge the valve element in a valve closing direction;
• a stationary core that is fixed to the main body;
• a first movable core that is configured to be attracted to the stationary core at a time of fuel injection in response to generation of a drive magnetic flux and thereby lift the valve element from a valve closing position to a first lift position;
• and
• a second movable core that, subsequent to lifting of the valve element to the first lift position by the first movable core, is configured to be attracted to the stationary core by the drive magnetic flux to further lift the valve element from the first lift position to a second lift position at which a lift amount of the valve element is greater than at the first lift position, wherein:
• the first movable core is formed in a tubular shape and has a hollow portion inside the first movable core, and the second movable core is received in the hollow portion in a state in which the second movable core is movable in the hollow portion;
• a solenoid coil, which is configured to generate the drive magnetic flux, is arranged to surround the first movable core and the stationary core;
• the first movable core and the second movable core are opposed to the stationary core in a lift direction of the valve element;
• a non-magnetic portion, which is formed in a circular ring shape and is made of a non-magnetic material, is disposed between the stationary core and the first movable core;
• in a lift state of the valve element at the second lift position, the first movable core is attracted to the stationary core by a magnetic flux of a first magnetic flux path, which is located on a radially outer side of the non-magnetic portion and passes through the first movable core and the stationary core, and the second movable core is attracted to the stationary core by a magnetic flux of a second magnetic flux path, which is located on a radially inner side of the non-magnetic portion and passes through the second movable core and the stationary core;
• and
• the valve element is driven at an end of the fuel injection such that the valve element is returned from the second lift position to the first lift position by conducting the magnetic flux only through the first magnetic flux path among the first magnetic flux path and the second magnetic flux path, and is temporarily stopped at the first lift position, and is then returned to the valve closing position by an urging force of the spring member.