| 摘要 |
PROBLEM TO BE SOLVED: To suppress fluctuation in stress to a rotary shaft in an oil seal so as to suppress increase of a contact area to the axial displacement of the rotary shaft by forming an inner circumference seal face of the oil seal into a polygon in a diameter directional vision. SOLUTION: An oil seal 10 is constructed of an elastically deformable ring type lip part 11 made of rubber, a steel back up ring 13 provided with a J- shaped cross section, and a rubber ring part 14 connected to one end of the lip part 11. In the lip part 11, a taper type inner circumference seal face S1 and a taper type relief face S2 are formed in the axial direction on the inner circumference side of a ring type space R which is formed between the lip part 11 and the back up part 13 and can store hydraulic oil of the predetermined oil pressure. In the taper type inner circumference seal face S1, toward the inside of a valve housing, approximately 2/3 of the axis directional dimension on the small diameter side is formed into a right dodecagon in the diameter directional cross section vision. In the taper type relief face S2, toward the inside of the valve housing, a large diameter side axial directional dimension is formed into a steep inclination with a length shorter than the axis directional dimension of the taper type inner circumference seal face S1. |
