Stretcher of elastic material, air filter unit capable of controlling air permeability including same, and mask including the air filter unit

An air filter unit capable of adjusting permeability comprising:

• a filter configured to filter particles contained in passing air by pores and a stretcher capable of expanding or contracting the filter in at least one direction, wherein:
• the filter is formed of an elastic material and has pores, sizes of which vary according to an operation of the stretcher;
• the stretcher comprises:
• a membrane in which the filter is installed;
• and
• a variable part installed around the membrane and configured to pull at least one side of the membrane and expand the elastic material,
• wherein the variable part comprises:
• a first wall connected to the membrane and having elasticity;
• a second wall constituting a hollow hole together with the first wall;
• a partition wall configured to partition the hollow hole into a first space and a second space;
• one or more connection holes formed in the partition wall so that air is able to move between the first space and the second space;
• and
• a sealing member installed in the first space and configured to seal the first space and the second space from an outside,
• wherein the first wall is extended toward the hollow hole as air escapes from the hollow hole, the first wall expands the membrane as the first wall is extended toward the hollow hole, and the pores of the filter are expanded depending on an expansion of the membrane, and
• wherein at least a portion of the second space is formed by the first wall, the first wall is extended toward the second space by injection of air from the second space to the first space according to a movement of the sealing member in one direction, and the first wall expands the membrane as the first wall is extended toward the second space.

A mask comprising:

• a mask body configured to cover the nose and mouth of a wearer;
• an air filter unit installed to the mask body;
• and
• a fixing member formed on both sides of the body and configured to fix the body to a face of the wearer,
• wherein:
• the air filter unit comprises a filter configured to filter particles contained in passing air by pores and a stretcher capable of expanding or contracting the filter in at least one direction, the filter,
• the filter is formed of an elastic material and has pores, sizes of which vary according to an operation of the stretcher,
• the stretcher comprises:
• a membrane in which the filter is installed;
• and a variable part installed around the membrane and configured to pull at least one side of the membrane and expand the elastic material,
• the variable part comprises:
• a first wall connected to the membrane and having elasticity;
• a second wall constituting a hollow hole together with the first wall;
• a partition wall configured to partition the hollow hole into a first space and a second space;
• one or more connection holes formed in the partition wall so that air is able to move between the first space and the second space;
• and
• a sealing member installed in the first space and configured to seal the first space and the second space from an outside,
• the first wall is extended toward the hollow hole as air escapes from the hollow hole, the first wall expands the membrane as the first wall is extended toward the hollow hole, and the pores of the filter are expanded depending on an expansion of the membrane, and
• at least a portion of the second space is formed by the first wall, the first wall is extended toward the second space by injection of air from the second space to the first space according to a movement of the sealing member in one direction, and the first wall expands the elastic material as the first wall is extended toward the second space.