US Patent 10974681 Vehicle occupant restraint system

It is provided a vehicle occupant restraint system comprising an airbag module and a backrest of a vehicle seat, wherein the airbag module is arranged on the backrest. The airbag module comprises an inflatable gas bag main chamber and an inflatable gas bag secondary chamber, wherein in the inflated condition the gas bag main chamber has a larger volume than the gas bag secondary chamber and wherein the gas bag main chamber and the gas bag secondary chamber are fluidically connected to each other via an overflow opening. The airbag module is arranged at the backrest of the vehicle seat such that in the inflated condition the gas bag secondary chamber is supported at the backrest of the vehicle seat.