A damper apparatus includes a stationary housing defining a cavity. A damper body rotatablely installed in the cavity has a head protruding to form a cylindrical guiding portion and a pushing portion defining two side ends apart from each other and rotatable sheets and stationary sheets are respectively...http://www.google.fr/patents/US7509710?utm_source=gb-gplus-shareBrevet US7509710 - Damper apparatus
