Patent ID: 11913552
Assignee: NOK CORPORATION
Field: Mechanical elements (Mechanical engineering)
Classification: CPC F | IPC F

Claim 3:
4. A gear reducer comprising:
a housing having an internal space in which a grease is stored;
a rotational shaft that is disposed in a hole in the housing and that bi-directionally rotates; and
a bi-directional sealing device acting to seal a gap between the housing and the rotational shaft, the bi-directional sealing device separating the internal space of the housing from an atmosphere side,
the bi-directional sealing device comprising:
an outer cylindrical portion mounted on the housing;
an inner cylindrical portion located radial inside the outer cylindrical portion;
a connecting circular annular portion connecting an atmosphere-side end of the outer cylindrical portion and an atmosphere-side end of the inner cylindrical portion in radial directions;
a main seal lip protruding radially inward from an inner peripheral surface of the inner cylindrical portion and having an internal-side inclined surface disposed on a side of the internal space and an atmosphere-side inclined surface disposed on the atmosphere side, the main seal lip being in slidable contact with an outer peripheral surface of the rotational shaft;
an auxiliary seal lip protruding radially inward and toward the internal space and extending from and contiguous with the internal-side inclined surface of the main seal lip, the auxiliary seal lip being in slidable contact with the outer peripheral surface of the rotational shaft;
multiple first spiral structures formed on the atmosphere-side inclined surface of the main seal lip and/or an inner peripheral surface of the auxiliary seal lip and extending obliquely; and
multiple second spiral structures formed on the atmospheric inclined surface of the main seal lip and/or the inner peripheral surface of the auxiliary seal lip and extending obliquely and symmetrically to the first spiral structures.