| 摘要 |
PROBLEM TO BE SOLVED: To stably set a cross section of an orifice passage with a target size by forming a deformation absorbing groove opened and extended on an outer peripheral surface along a recessed groove in a state that the pocket-shaped recessed parts are not connected to one another under a condition that it is covered by at least an outer cylindrical member. SOLUTION: A pair of deformation absorbing grooves 50, 50 are formed on a rubber 44 for forming an orifice on both sides through a recessed groove 46 in the width direction of a circumferential groove 42. These deformation absorbing grooves 50 are respectively extended in the circumferential direction along the recessed groove 46 in a state that a positon separated from the recessed groove 46 by a specific distance in the width direction of the circumferential groove 42, keeps an approximately constant interval with respect to the recessed groove 46. The lengths in the circumfernetial direction of the deformation absorbing groove 50 are lengths slightly short to a window part 34. By applying this structure, the expanded deformation in the direction along an outer cylindrical fitting 14 is generated with priority to a wall surface of the deformation absorbing groove 50, and the swelling deformation amount of the wall surface of the recessed groove 46 is reduced for the expanded deformation. Accordingly the cross section of the orifice passage 72 can be effectively and stably ensured. |
