Ultra-heavy chain type window opening and closing device

The utility model discloses an ultra-heavy chain type window opening and closing device. The speed reducer comprises a shell, the shell comprises end covers, the end covers are arranged at the two ends of the shell, a chain box is arranged in an inner cavity of the shell, a chain is installed on the chain box, a speed reducer gear set is arranged in an inner cavity of the shell, and the speed reducer gear set is used in cooperation with the chain. According to the utility model, the chain sheet structure is redesigned; the precision of the chain sheet is ensured by using primary punching and secondary fine punching; the chain sheets are changed into surface contact when being stressed; therefore, the chain has enough strength; a large-modulus gear is used as the gear modulus, gear specialsteel and tooth surface high-frequency quenching are selected to guarantee the service life of the speed reducer part, a chain head structure is designed, an angle larger than 90 degrees is formed between the center of a chai