Arc extinguishing chamber for direct-current circuit breaker and use method of arc extinguishing chamber

The invention provides an arc extinguishing cover for a direct-current circuit breaker and a using method, the arc extinguishing cover comprises a shell and arc extinguishing grid sheets uniformly arranged on the inner side of the shell, the shell is provided with a protection assembly, the protection assembly comprises an air leakage box which is arranged on one side of the shell and corresponds to the arc extinguishing grid sheets, an air outlet hole is formed in the position, corresponding to the air leakage box, of the shell, and the air outlet hole is communicated with the air leakage box. An inner box is movably connected to the inner side of the air leakage box, a first through hole is formed in the side wall of the inner box, a second through hole is formed in the side wall of the air leakage box, a heat expansion and cold contraction piece is arranged between the inner wall of the inner box and the side wall of the shell, and the first through hole and the second through hole are in a staggered state