Patent ID: 8516657

Claim:
A hinge device comprising: a case ( 11 , 41 , 51 ); a shaft body ( 12 , 52 ) that is at least partially inserted into the case, and is rotatable relative to the case; first and second chambers ( 14 a - 14 b , 43 a - 43 b , 54 a - 54 b ) formed between the case and shaft body; viscous fluid that is filled in the first and second chambers formed between the case and the shaft body; an orifice ( 44 , 48 , 57 ) that narrows a flow passage of the viscous fluid flowing to the second chamber ( 14 b , 43 b , 54 b ) from the first chamber ( 14 a , 43 a , 54 a ) so as to resist relative rotation of the shaft body when the shaft body is rotated relative to the case; a first valve ( 16 , 56 ) interposed between the shaft body and the case; and a second valve ( 28 , 78 ) that is disposed in a space ( 26 , 76 ) without the viscous fluid formed in the case or the shaft body, the second valve movable in the space and facing the viscous fluid filled in the first chamber, wherein, when the shaft body rotates in a first direction relative to the case, the first chamber on a high-pressure side and the second chamber on a low-pressure side are compartmentalized by the first valve ( 16 , 56 ) so that the viscous fluid flows to the second chamber on the low-pressure side from the first chamber on the high-pressure side via the orifice and thereby creates a damping force, wherein, when the shaft body rotates in a second direction opposite to the first direction relative to the case, the first chamber is reversely positioned on the low-pressure side and the second chamber is positioned on the high-pressure side, the first valve ( 16 , 56 ) not compartmentalizing the first chamber on the low-pressure side and the second chamber on the high-pressure side from each other so that the viscous fluid flows to the first chamber on the low-pressure side from the second chamber on the high-pressure side without the damping force being generated or with the damping force being reduced, and wherein, when a pressure in the first chamber reaches the predetermined pressure, the second valve ( 28 , 78 ) moves in the space so that a volume of the first chamber increases and a bypass flow passage ( 38 , 81 ) connecting the first chamber with the second chamber is formed.