Variable damping shock absorber

A variable damping shock absorber, provided to be quickly installed into a slide rail, for buffering when the slide rail retracts inward under a force, comprising:

• a housing, being a round tubular thin shell structure, and having two ends recessed inwards to form a ring rim provided for installing two stop blocks, and each of the stop blocks having a through hole formed at the center thereof;
• a piston rod, having two ends defined as a first end and a second end respectively, and the first end being movably installed in the housing, and the second end being extended to and exposed from the housing for purpose of an external connection;
• two piston blocks, including a first piston block and a second piston block, and the first piston block having the first end disposed at the piston rod, and the second piston block disposed on the piston rod and spaced apart from the first piston block, and a first piston rubber ring being installed between the first piston block and inner wall of the housing to form an airtight seal, and a second piston rubber ring being installed between the second piston block and the inner wall of the housing to form an airtight seal;
• a first elastic element, installed between an end of the housing and the first piston block, such that the piston rod when not being forced will be extended to the outside by resilience of the first elastic element;
• a conical seat, movably installed between the first piston block and the second piston block, and having a conical surface formed at middle part of the conical seat and corresponding to the moving direction of the piston rod, at least a third piston rubber ring movably sheathed on the conical surface, such that the third piston rubber ring moves on the conical surface with the relative displacement of the piston rod;
• and
• a second elastic element, installed between the conical seat and the second piston block, for abutting the conical seat against the first piston block by resilience of the second elastic element;
• thereby, when an exerted pressure increases, the third piston rubber ring moves to a position where a surface of the conical seat is closest to the inner surface of the housing, and squeezes the inner surface of the housing to increase friction and achieve the effect of enhancing a damping effect.