A solenoid valve moves an armature back and forth translationally between
valve open and valve closed positions without the armature having any
sliding engagement with any fixed valve part. This is accomplished by
supporting the armature with a spring having one periphery engaging a
fixed valve surface and another periphery engaging the armature so that
armature movement causes flexure of the spring, but no sliding contact.
This helps prevent generation of dirt within the valve and ensures
accurate armature movement to make the valve durable and reliable.
Springs in both washer and cylindrical helical shapes can accomplish
this, and the armatures supported by such springs can accommodate valve
closing seals of different materials and shapes.