Inflator and airbag device

An inflator comprising:

• an inflator case that is configured from a bottomed cylindrical upper case and a bottomed cylindrical lower case that closes an opening in an end portion of the upper case, with the inflator case having an upper combustion chamber, in which a gas generant that generates gas by combustion is accommodated and which is positioned on the upper case side, and a lower combustion chamber, in which a gas generant that generates gas by combustion is accommodated and which is positioned on the lower case side, the upper combustion chamber and the lower combustion chamber being partitioned by a partition wall, and with the inflator case having a peripheral wall in which a plurality of upper gas discharge holes corresponding to the upper combustion chamber and a plurality of lower gas discharge holes corresponding to the lower combustion chamber are formed;
• a first inner cylinder member that is disposed on a bottom wall portion side of the lower case inside the inflator case, with flash holes communicated with the lower combustion chamber being formed in the first inner cylinder member, and with a transfer charge for combusting the gas generant inside the lower combustion chamber being accommodated inside the first inner cylinder member;
• a second inner cylinder member that is disposed on the bottom wall portion side of the lower case inside the inflator case, the second inner cylinder member having an upper end portion that penetrates the partition wall and is positioned in a lower portion of the upper combustion chamber, with flash holes communicated with the upper combustion chamber being formed in the upper end portion, and with a transfer charge for combusting the gas generant inside the upper combustion chamber being accommodated inside the second inner cylinder member;
• a first igniter that is disposed on the bottom wall portion side of the lower case and is configured to be capable of igniting the transfer charge inside the first inner cylinder member;
• a second igniter that is disposed on the bottom wall portion side of the lower case and is configured to be capable of igniting the transfer charge inside the second inner cylinder member;
• and
• a cylindrical heat-insulating material that is disposed on a radial direction outer side of the second inner cylinder member.