Damper and vehicle seat equipped with the damper

A damper comprising:

• a vessel for accommodating a viscous fluid in its interior;
• a partitioning member provided in the interior of said vessel linearly movably in an axial direction with respect to said vessel to partition the interior of said vessel for accommodating the viscous fluid into at least first and second chambers in the axial direction, said axial direction having a first direction from the second chamber to the first chamber, and a second direction from the first chamber to the second chamber opposite to the first direction;
• at least one communicating hole formed in said partitioning member so as to allow the first and second chambers in the interior of said vessel to communicate with each other through a variable passage whose passage cross-sectional area changes;
• flow limiting means for limiting the flow of the viscous fluid in the first chamber into the second chamber through said communicating hole when an internal pressure of the viscous fluid accommodated in the first chamber has exceeded a fixed value on the basis of the linear movement of said partitioning member in the first direction with respect to said vessel,
• wherein said flow limiting means includes:
• a variable passage forming member which has a through hole which, in a first end face in the axial direction of said variable passage forming member, is open to the first chamber, said variable passage forming member being fitted to said partitioning member linearly movably in such a manner as to oppose, at a second end face in axial direction of said variable passage forming member, a side face in the axial direction of said partitioning member, so as to form the variable passage communicating with, on one side, the through hole and, on another side, said communicating hole in cooperation with the side face in the axial direction of said partitioning member;
• and an annular elastic member surrounding the variable passage and disposed between the second end face in the axial direction of the said variable passage forming member and the side face in the axial direction of said partitioning member, so as to brake the relative linear movement in the axial direction of said partitioning member with respect to said vessel.

A damper comprising:

• a vessel for accommodating a viscous fluid in its interior;
• a partitioning member provided in the interior of said vessel linearly movably in an axial direction with respect to said vessel to partition the interior of said vessel for accommodating the viscous fluid into at least first and second chambers in the axial direction, said axial direction having a first direction from the second chamber to the first chamber, and a second direction from the first chamber to the second chamber opposite to the first direction;
• at least one communicating hole formed in said partitioning member so as to allow the first and second chambers in the interior of said vessel to communicate with each other through a variable passage whose passage cross-sectional area changes;
• flow limiting means for limiting the flow of the viscous fluid in the first chamber into the second chamber through said communicating hole when an internal pressure of the viscous fluid accommodated in the first chamber has exceeded a fixed value on the basis of the linear movement of said partitioning member in the first direction with respect to said vessel,
• wherein said flow limiting means includes:
• a variable passage forming member which is movably fitted to said partitioning member and has, in a first end face of the variable passage forming member in the axial direction facing a side face in the axial direction of said partitioning member, a communicating groove which is open at a first end portion of the communicating groove to said first chamber and is open at a second end portion of the communicating groove to said communicating hole;
• and an annular elastic member which is located between the first end portion and the second end portion of the communicating groove in a radial direction and fitted to the side face in the axial direction of said partitioning member, such that the variable passage for effecting mutual communication between the first and second chambers in the interior of said vessel by means of said communicating hole by allowing said first chamber and said communicating hole to communicate is formed by the annular elastic member and the first end face in the axial direction of said variable passage forming member having the communication groove, so as to brake the relative linear movement in the axial direction of said partitioning member with respect to said vessel.