Patent ID: 7204354
Filing Date: 2007-04-17
Classification: F16F

Abstract:
1. A rotary damper comprising: a casing; a rotor having a shaft portion pivoted to a boss portion of said casing and a vane formed in an outer periphery of the shaft portion; a first oil chamber and a second oil chamber sectioned in both sides of the vane of said rotor within said casing, an outer lid attached to an outer side surface of said casing, a first oil passage and a second oil passage respectively communicating said first oil chamber and the second oil chamber provided in parallel between an outer side surface of said casing and an inner side surface of said outer lid, each of said first oil passage and the second oil passage has an outer lid side oil passage portion formed between a groove formed in the inner side surface of said outer lid and the outer side surface of said casing, a casing side oil passage portion formed between a groove formed in the outer side surface of said casing and the inner side surface of said outer lid, and a connection portion communicating said outer lid side oil passage portion with the casing side oil passage portion, said first oil passage being provided with a first check valve allowing a flow only from the first oil chamber to the second oil chamber, said second oil passage being provided with a second check valve allowing a flow only from the second oil chamber to the first oil chamber, an orifice plate being movably provided so as to face both the connection portion of said first oil passage and the connection portion of the second oil passage, wherein said orifice plate has a first orifice hole group having a plurality of orifice holes in correspondence to said oil passage so as to connectt the outer lid side oil passage portion of the first oil passage with the casing side oil passage portion, and a second orifice hole group constituted by a plurality of orifice holes in correspondence to said oil passage so as to connect the outer lid side oil passage portion of the second oil passage with the casing side oil passage portion, at each of a plurality of movement stop positions.