Patent ID: 9523333
Filing Date: 2016-12-20
CPC Classification: F02D,F02M

Claim Text:
1. An actuator unit for injecting a fuel into a combustion chamber of an internal combustion engine, comprising: an electrically conductive excitation winding disposed in a housing, a first ferromagnetic circuit loop including a return through a projection of the housing, a second ferromagnetic circuit loop through the housing without passing through the return an armature configured to move along an axis between: wherein the armature is biased along the axis toward the idle position by a spring holding force of a spring element, wherein a current flowing through the excitation winding produces a magnetic field that provides (a) a magnetic holding force acting on the armature in the same direction as the spring holding force provided by the spring element, and (b) a magnetic motive force acting on the armature in the opposite direction as the magnetic holding force and spring holding force, wherein when the current flowing through the excitation winding is less than or equal to a predetermined current value, the current produces a magnetic holding force which, in combination with the spring holding force, is greater than the magnetic motive force, thereby holding the armature in the idle position as magnetic flux passes through the first ferromagnetic circuit loop, and wherein when the current flowing through the excitation winding exceeds the predetermined current value, the magnetic motive force produced by the current exceeds the magnetic holding force combined with the spring holding force, which produces an air gap in the region of the surface segment, breaking the first ferromagnetic circuit loop and, resulting in the magnetic holding force decreasing with a steep gradient and the armature moving toward the working position.