Drive device for fuel injection device, and fuel injection system
A drive device capable of detecting individual variations of an injection quantity of a fuel injection device of each cylinder and adjusting a current waveform provided to an injection pulse width and a solenoid such that the individual variations of the fuel injection devices are reduced. The fuel injection device in the present invention includes a valve body that close a fuel passage by coming into contact with a valve seat and opens the fuel passage by separating from the valve seat and a magnetic circuit constructed of a solenoid, a fixed core, a nozzle holder a housing and a needle and when a current is supplied to the solenoid a magnetic suction force acts on the needle and the needle has a function to open the valve body by colliding against the valve body after performing a free running operation and changes of acceleration of the needle due to collision of the needle against the valve body are detected by a current flowing through the solenoid.
1. A drive device configured to drive a fuel injection device by controlling energization and non-energization of a solenoid of the fuel injection device, the fuel injection device comprising:
a valve body that is closed by being brought into contact with a valve seat, and that is opened by being separated from the valve seat,
a needle that is driven by a magnetic suction force from the solenoid and that energizes the valve body in a valve opening direction when coming into contact with the valve body, wherein
in a valve closed state, an air gap is provided between the valve body and a contact surface of the needle and is used by the needle to come into contact with the valve body after performing a free running operation by the needle due to the magnetic suction force from the solenoid, and
the drive device is configured to reduce a valve opening current which started energizing the solenoid in a state in which the valve body is closed, before the valve body starts to open.
2. The drive device according to claim 1 , wherein
the drive device reduces the valve opening current before the valve body starts to open after the free running operation of the needle toward the valve body.
3. The drive device according to claim 1 , wherein
the drive device includes a step-up circuit configured to step up a battery voltage, and
the step up voltage of the step-up circuit is applied to the solenoid to supply the valve opening current, and the applying of the step up voltage is stopped before the valve body starts to open.
4. The drive device according to claim 1 , wherein
the drive device opens the valve body in a state in which the valve opening current is reduced.
5. The drive device according to claim 4 , wherein
the drive device supplies a current smaller than the valve opening current during a period until the valve body closes after the valve body opens.
6. The drive device according to claim 1 , wherein
the needle defines a lateral protrusion, and on a first side thereof the lateral protrusion defines the air gap.