Seal structure of spline axis and gasket null for spline axis

摘要

PROBLEM TO BE SOLVED: To ensure the good sealing performance over the whole periphery of a spline shaft. SOLUTION: A U packing 5 is provided with lips 9, 10 on both inner and outer sides. On the inner peripheral side of the inner peripheral side lip 10, a projected sealing part 12 which has about the same width W2 as the groove width W1 of a spline groove 7, and which has a larger radius R2 of curvature than the radius R1 of curvature of the spline groove 7, is formed. A rib 13, the width W3 of which is smaller than the groove width M1, is formed between both the inner and outer lips 9, 10 which correspond to the projected sealing part 12. Then, in state where the packing 5 is loaded in a spline shaft 6, a gap is produced between the spline groove 7 and the projected sealing part 12 due to the difference in their radiuses of curvature, but the gap is closed by the force transmitted to only the projected sealing part 5 toward the inner peripheral side through the narrower rib 13. Thus, the force from the rib 13 is not transmitted to the inner peripheral lip 10 other than the projected sealing part 12, and the outer peripheral surface of the spline groove 7 and the outer periplaeral surface of the spline shaft 6 are positively sealed.