Frequency sensitive shock absorber
The present disclosure relates to a frequency sensitive shock absorber, and the frequency sensitive shock absorber includes a piston rod coupled so that one side is located inside a cylinder and the other side is located outside the cylinder, a main valve coupled to the piston rod and partitioning an inner space of the cylinder into a compression chamber and a tension chamber, a sub-piston rod coupled to one side of the piston rod and interlocked with the piston rod to reciprocate along a longitudinal direction of the cylinder, and a sub-valve module coupled to the sub-piston rod and generating a damping force according to a frequency during a tension stroke.
1 . A frequency sensitive shock absorber comprising:
a piston rod coupled so that one side is located inside a cylinder and the other side is located outside the cylinder;
a main valve coupled to the piston rod and partitioning an inner space of the cylinder into a compression chamber and a tension chamber;
a sub-piston rod coupled to one side of the piston rod and interlocked with the piston rod to reciprocate along a longitudinal direction of the cylinder; and
a sub-valve module coupled to the sub-piston rod and generating a damping force according to a frequency during a tension stroke,
wherein the sub piston rod includes a working fluid discharge path formed to communicate with an inside of the sub-valve module to discharge a working fluid to adjust a pressure inside the sub-valve module when the pressure inside the sub-valve module increases due to the working fluid flowing into the sub-valve module during the tension stroke at low frequency,
wherein the sub piston rod includes
a head portion coupled to one side of the piston rod and
a rod body portion extending along a longitudinal direction of the rod body portion from a lower surface of the head portion and having a size of a cross section crossing the longitudinal direction of the rod body portion formed smaller than a size of a cross section of the head portion crossing the longitudinal direction of the head portion, and
wherein the working fluid discharge path includes
a first discharge path formed on the lower surface of the head portion and concavely formed from an external profile of the head portion to an outer circumferential surface of the rod body portion in a radial direction toward the rod body portion, and
a second discharge path formed on the outer circumferential surface of the rod body portion and formed by a set length along the longitudinal direction of the rod body portion.
2 . The frequency sensitive shock absorber of claim 1 , wherein a rod insertion groove is formed in the head portion by a set depth from an upper surface to the lower surface so that one side of the piston rod is inserted into the head portion.
3 . The frequency sensitive shock absorber of claim 1 , wherein a first fluid flow path through which the working fluid filling the inner space of the cylinder is introduced, flowed and discharged is formed when compression and tension strokes are performed along the longitudinal direction of the cylinder is formed inside the piston rod.
4 . The frequency sensitive shock absorber of claim 3 , wherein a second fluid flow path through which the working fluid delivered from the piston rod is introduced, flowed, and discharged is formed inside the sub-piston rod.
5 . The frequency sensitive shock absorber of claim 4 , wherein the sub-valve module includes
a housing coupled to the rod body portion and having pilot chambers formed at upper and lower sides to be filled with the working fluid introduced through the second fluid flow path,
a retainer located at a lower side of the housing, coupled to the rod body portion, and having a main chamber to be filled with the working fluid introduced through the second fluid flow path,
a first pilot valve located between the housing and the retainer, coupled to the rod body portion, and partitioning the pilot chamber and the main chamber, and
a second pilot valve located between the head portion and the housing, coupled to the rod body portion, and elastically deformed according to a pressure change in the pilot chamber.
6 . The frequency sensitive shock absorber of claim 5 , wherein the sub-valve module further includes an inlet disk coupled to the rod body portion to be located between the housing and the first pilot valve and having one or a plurality of first slits for causing the second fluid flow path and the pilot chamber to communicate with each other.
7 . The frequency sensitive shock absorber of claim 5 , wherein the housing includes
one surface of the housing in which a first hollow is formed, the first hollow extending in a longitudinal direction of the housing and allowing the rod body portion to penetrate,
a first outer wall protruding upward and downward from an edge of the one surface of the housing and extending in a circumferential direction of the housing, and
a first inner wall extending to protrude upward and downward at a position spaced apart in the radial direction from the first hollow on the one surface of the housing.
8 . The frequency sensitive shock absorber of claim 7 , wherein a separation space is formed between the sub-piston rod and the upper first inner wall when the housing is coupled to the sub-piston rod.
9 . The frequency sensitive shock absorber of claim 8 , wherein the sub-valve module further includes an outlet disk coupled to the rod body portion to be located between the housing and the second pilot valve and having one or a plurality of second slits for causing the working fluid discharge path, the separation space, and the upper pilot chamber to communicate with each other.
10 . The frequency sensitive shock absorber of claim 5 , wherein a hollow through which the sub-piston rod passes is formed in the retainer,
wherein the retainer includes
an outer wall protruding upwardly from an edge of one surface of the retainer facing the housing and extending in a circumferential direction of the retainer, and
inner walls formed to protrude and to be spaced apart by a set angle along a circumferential direction of the hollow at a position spaced apart from the hollow in the radial direction on the one surface of the retainer facing the housing, and
wherein the main chamber is formed between the outer wall and the inner walls.
11 . The frequency sensitive shock absorber of claim 10 , wherein the retainer further includes a plurality of protrusions formed to protrude and to be spaced apart by a set angle along the circumferential direction of the retainer on the one surface of the retainer to be located inside the main chamber.
12 . The frequency sensitive shock absorber of claim 10 , wherein a flow path is formed between one inner wall and an adjacent inner wall so that the working fluid is introduced into the main chamber.