Magnetorheological damper with variable damping channel length for elevator falling buffering

A gland and a pressing barrel are combined into a whole, when the magneto-rheological damper is impacted and pressed downwards, the pressing barrel slides along an outer barrel end cover and the inner wall of an outer cylinder barrel, the lower bottom of the pressing barrel moves downwards, thrust is generated on magneto-rheological fluid, and then the magneto-rheological fluid is buffered; the magnetorheological fluid flows along a gap between the inner wall of the pressing cylinder and the coil column; when current is applied to the magnet exciting coil, a closed magnetic field loop can be formed at the damping channel along with downward movement of the pressing cylinder, so that damping force is generated, the magnitude of the damping force can be adjusted according to the magnitude of the current, and controllability of the damping force is achieved. The length of a damping channel can be changed in the impact process, viscous damping work is reduced, and the coulomb force control effect is enhanced; dif