Ultralow-frequency nonlinear quasi-zero stiffness vibration isolator

The utility model discloses an ultralow frequency non-linear quasi-zero stiffness vibration isolator, which relates to the technical field of vibration isolators and comprises a bottom shell, a top plate is arranged at the top of the bottom shell, connecting cylinders are fixedly connected to the interiors of the two ends of the bottom shell, limiting cavities are formed in the interiors of the tops of the connecting cylinders, and connecting columns are arranged in the limiting cavities. A limiting ring is fixedly connected to the outer side of the bottom of the connecting column, the top of the connecting column is fixedly connected to the bottom face of the top plate, a first spring is arranged on the outer side of the connecting cylinder, one end of the first spring is fixedly connected to the bottom face in the bottom shell, and the other end of the first spring is fixedly connected to the bottom face of the top plate; two symmetrically-arranged negative stiffness assemblies are fixedly connected into th