Anti-friction helical spring assembly to prevent one end of a spring from rotating during expansion or compression of the spring

A spring assembly for an electromagnetic actuator, the actuator having an armature mounted for movement between two electromagnets and a shaft operatively associated with said armature, said spring assembly comprising:

• a housing having a surface feature and coupled to the actuator the housing defining an interior space,
• a helical spring having a longitudinal axis and being disposed in at least a portion of the interior space of said housing so as to be compressed and allowed to expand, said spring having first and second ends with said second end biasing the shaft, a spring retainer engaging said first end of said spring, said spring retainer having a surface feature therein, and
• a ball bearing received by said surface feature of said housing and said surface feature of said spring retainer so as to be disposed on said longitudinal axis,
• wherein, when said spring is compressed and then expanded, torque produced by said spring is transferred to said ball bearing which rotates with respect to said housing, permitting said first end of said spring to rotate freely while substantially preventing torque from being transferred from said spring to the shaft and armature.

An electromagnetic actuator comprising:

• a housing,
• an upper electromagnet in said housing,
• a lower electromagnet in said housing and spaced from said upper electromagnet,
• an armature mounted for movement between said upper and lower electromagnets,
• shaft structure operatively associated with said armature for movement therewith, and
• a helical spring assembly biasing said shaft structure, said spring assembly comprising:
• an adjusting screw threadedly coupled with said housing and having a surface feature therein,
• a helical spring having a longitudinal axis and being disposed in said adjusting screw so as to be compressed and allowed to expand, said spring having first and second ends, said second end engaging said shaft structure,
• a spring retainer engaging said first end of said spring, said spring retainer having a surface feature therein, and
• a ball bearing received by said surface feature of said adjusting screw and said surface feature of said spring retainer so as to be disposed on said longitudinal axis,
• wherein, when said spring is compressed and then expanded, torque produced by said spring is transferred to said ball bearing which rotates with respect to said adjusting screw, permitting said first end of said spring to rotate freely while substantially preventing torque from being transferred from said spring to said shaft structure and armature.