BUMPER RUBBER FOR SHOCK ABSORBER

1 . A bumper rubber for a shock absorber, comprising:

a body portion in which a cylindrical coupling hole vertically penetrates such that a piston rod is connected thereto;

one or more inner grooves formed concavely along a circumferential direction of the coupling hole and arranged in a vertical direction; and

an inner protrusion protruding from an inner peripheral surface of the inner groove radially inward, wherein a laterally protruding end of the inner protrusion comes into close contact with an outer surface of the piston rod when the body portion is vertically compressed.

2 . The bumper rubber according to claim 1 , wherein the inner grooves are continuously formed along the circumferential direction of the coupling hole, and

a plurality of inner protrusions are arranged along a circumferential direction of the inner grooves.

3 . The bumper rubber according to claim 2 , wherein the inner groove is formed to have a concavely curved surface along a vertical direction of the coupling hole.

4 . The bumper rubber according to claim 2 , wherein the protruding end of the inner protrusion forms a convexly curved surface in the vertical direction and the circumferential direction of the coupling hole.

5 . The bumper rubber according to claim 4 , wherein the inner protrusion is formed to have an oval surface with a length along the vertical direction of the coupling hole.

6 . The bumper rubber according to claim 2 , wherein the protruding end of the inner protrusion further protrudes radially inward than upper and lower ends of the inner groove.

7 . The bumper rubber according to claim 2 , wherein the inner protrusion is inclined in the circumferential direction of the coupling hole so as to form a helical shape along the vertical direction of the coupling hole.

8 . The bumper rubber according to claim 1 , wherein outer grooves are continuously formed on the outer surface of the body portion along the circumferential direction, and

the outer grooves are disposed in a section between the upper end and the lower end of the inner groove.

9 . The bumper rubber according to claim 1 , wherein an air passage is concavely formed at the upper end of the body portion such that air inside the coupling hole is ventilated to the outside,

one end of the air passage communicates with the coupling hole, and

the other end of the air passage communicates with the outside of the body portion.

10 . The bumper rubber according to claim 10 , wherein the air passage comprises:

a horizontal portion formed concavely at the upper end of the body portion, one end of the horizontal portion communicating with the coupling hole, the other end of the horizontal portion communicating with the outside of the body portion; and

a vertical portion extending to be bent downward from the one end of the horizontal portion, and formed concavely on the outer surface of the body portion.

11 . The bumper rubber according to claim 8 , further comprising one or more upper protrusions on the inner peripheral surface of the coupling hole,

wherein the one or more upper protrusions are spaced apart from each other in an upper portion of the inner groove and come into contact with the outer surface of the piston rod, and

the upper protrusions are disposed on the same line as the air passage with respect to a vertical central line of the coupling hole.

12 . The bumper rubber according to claim 1 , further comprising a contact end in a lower side of the body portion,

wherein the contact end is curvedly bent toward a central axis of the coupling hole,

a lower portion of the contact end comes into close contact with an upper end of the cylinder, and

a plurality of outer protrusions are arranged on an outer surface of the contact end along a circumferential direction so as to come into close contact with the upper end of the cylinder when the bumper rubber is compressed.

13 . The bumper rubber according to claim 12 , wherein the outer surface of the contact end is formed to have a convexly curved surface in the vertical direction, and

the outer protrusion forms a convexly curved surface in the vertical direction and the circumferential direction.