A tire-pressure control apparatus includes an air pump driven by a rotating wheel to supply compressed air to a tire air chamber, a mechanical control valve that permits and prohibits supply of compressed air from the air pump to the tire air chamber, a valve-state detection sensor that detects the state...http://www.google.com.tw/patents/US7882733?utm_source=gb-gplus-share專利 US7882733 - Tire-pressure control apparatus
