Electromagnetic actuator

An electromagnetic actuator and valve assembly including:

• an electromagnetic actuator;
• valve means operatively connected to said actuator and actuated thereby to control the fluid flow through said valve means;
• said actuator comprising;
• a substantially cylindrical housing, first and second exciting coils disposed in said housing in axially aligned relationship, a fixed core having first and second poles positioned radially inwardly of said first and second coils, respectively, said fixed core defining therein an axial through-hole extending through said first and second poles, an axially elongated rod extending slidably through said axial through-hole, a first movable core disposed to cooperate with said first pole to define a first air gap and fixed to said rod adjacent to one end thereof for axial movement with said rod, stop means provided on said housing adjacent to said first movable core, first biasing means for resiliently biasing said first movable core axially toward said stop means, a second movable core disposed to cooperate with said second pole to define a second air gap and mounted on said rod for axial sliding movement thereon;
• said valve means comprising;
• a valve housing connected to the end of said actuator housing adjacent to said second movable core and defining fluid inlet and outlet and a fluid passage extending between said fluid inlet and outlet, a valve seat in said fluid passage between said fluid inlet and outlet and a valve member disposed in said fluid passage and connected to said second movable core of said actuator for movement therewith to cooperate with said valve seat to control the fluid flow through said fluid passage;
• second biasing means operative to bias said second movable core in the axial direction opposite to the direction in which said first movable core is biased by said first biasing means;
• and
• means for limiting the relative movement between said rod and said second movable core away from each other;
• the arrangement being such that said valve member is positioned at a first position in contact with said valve seat when said first coil is energized, such that said valve member is positioned at a second position remote from said valve seat when said second coil is energized and such that said valve member is positioned at a third position between said first and second positions when said first and second coils are both deenergized.