Telescopic compensator for sleeve

The utility model discloses a telescopic compensator for a casing pipe. The device comprises a telescopic central pipe, an inner pipe, a first connecting sleeve, a shear pin, a protective pipe and a reducing sleeve, the inner wall of the telescopic central pipe is slidably connected with an inner pipe; the outer side of the telescopic central pipe is sleeved with a first connecting sleeve; threaded holes are symmetrically formed in one end of the first connecting sleeve; shear pins are in threaded connection with the inner walls of the threaded holes; a limiting groove is formed in the end, close to the shear pin, of the telescopic center pipe. The shear pin is clamped with the limiting groove; the outer side of the telescopic central pipe is sleeved with a protective pipe; internal threads are formed in the inner wall of one end of the protective tube close to the first connecting sleeve; external threads are arranged at the end, close to the protective tube, of the first connecting sleeve, the first connect