US Patent 10212968 Smoking article with a valve

A smoking article is provided, including a combustible heat source having opposed front and rear faces; one or more airflow channels extending from the front face to the rear face of the combustible heat source; an aerosol-forming substrate downstream of the rear face of the combustible heat source; and a thermostatic bimetal valve located between the rear face of the combustible heat source and the aerosol-forming substrate, wherein the thermostatic bimetal valve is arranged to deform from a first position, in which the valve substantially prevents or inhibits fluid communication between the one or more airflow channels and the aerosol-forming substrate, to a second position, in which the one or more airflow channels and the aerosol-forming substrate are in fluid communication, when the thermostatic bimetal valve is heated to above a threshold temperature.