Patent ID: 7322392

Claim:
A tire pump comprising a single-stage passive air pump attachable to a tire valve stem which is devoid of a tire valve and which is attached to a vehicle wheel supporting a tire containing a gas, wherein the passive air pump has an air inlet in direct fluid communication with the atmosphere and has an air outlet in direct fluid communication with the gas in the tire, wherein the passive air pump is operable by transient pressure pulses of the gas in the tire to suck in an air volume from the atmosphere through the air inlet after a present one of the transient pressure pulses and to pump at least some of the sucked-in air volume through the air outlet into the tire during a next-in-time one of the transient pressure pulses to the present one of the transient pressure pulses, and wherein the passive air pump includes first and second check valves and includes a piston assembly having a piston and having a piston rod attached to the piston with the piston rod having a free end, wherein the passive air pump includes a gas path containing air and fluidly connecting together the air inlet and the air outlet, wherein the first check valve is disposed in the gas path toward the air inlet, wherein the second check valve is disposed in the gas path toward the air outlet, wherein the free end of the piston rod is movable to compress and suction the air in the gas path between the first and second check valves, and wherein the piston is in direct fluid communication with the gas in the tire.