Patent ID: 8544766

Claim:
A scent dispenser, comprising: a piston cylinder having a sidewall and a pair of opposed ends, one of which is closed and the other of which is open, said sidewall surrounding an interior of said piston cylinder; a piston positioned in said piston cylinder for reciprocating movement relative thereto between a depressed position and an extended position, said piston including an imperforate peripheral wall surrounding an internal chamber which is in pneumatic communication with said interior of said piston cylinder, a first open end and a second open end opposite said first open end, said second open end of said piston being mounted within said interior of said piston cylinder and being positioned proximate said one end of said piston cylinder when said piston is in its said depressed position and distal from said one end of said piston cylinder when said piston is in its said extended position, and said first open end of said piston being positioned proximate said other end of said piston cylinder when said piston is in its said depressed position and distal from said other end of said piston cylinder when said piston is in its said extended position; a cover for closing said first open end of said piston; a ventilation port located proximate said first open end of said piston, said ventilation port being in pneumatic communication with said internal chamber of said piston and with the atmosphere when said piston is in its said depressed position and in its said extended position; an ambient air modification material received within said internal chamber of said piston; and urging means for urging said piston from its said depressed position into its said extended position, whereby air is drawn from the atmosphere into said scent dispenser through said ventilation port, then through said ambient air modification material into said interior of said piston cylinder, and wherein movement of said piston from its extended position to its depressed position forces air from said interior of said piston cylinder through said ambient air modification material then through said ventilation port to the atmosphere, a position-limiting mechanism for limiting movement of said piston, said position-limiting mechanism including a projecting member projecting from said sidewall of said piston cylinder toward said piston and a first groove in the external surface of said peripheral wall of said piston for slidably receiving said projecting member such that said first groove guides said piston toward its extended position with said projecting member slidably received in said first groove, said first groove having an end arranged to catch said projecting member so as to stop movement of said piston at its extended position.