US Patent 8984717 Floor hinge

A self-returning hinge assembly utilizing a spring disposed along a linearly displaceable guide shaft element mounted through a polymeric guide plate disposed in substantial alignment with an aperture supporting an elongated proximal portion of the guide shaft. Upon displacement of the door from a pre-established set point, the spring is compressed thereby generating a biasing force along the guide shaft to bring the door back to the pre-established set point. The linear travel path of the guide shaft element is maintained by the guide plate.