Lubricant sealing structure, strain wave gearing, and actuator

A lubricant sealing structure which prevents lubricant from leaking out, from an interior of a device provided with a first member and a second member that rotate relative to one another about a central axis, through a gap portion between the first and second members, the lubricant sealing structure comprising:

• a labyrinth seal for sealing the gap portion, the labyrinth seal being formed between a first surface portion on a first-member side and a second surface portion on a second-member side, the first and second surface portions facing each other;
• oil-repellent surfaces provided with oil repellency with respect to the lubricant, the oil-repellent surfaces being formed on each of the first and second surface portions;
• and
• an upstream-side oil-repellent surface provided with oil repellency, the upstream-side oil-repellent surface being formed on at least one of a first upstream-side surface portion and a second upstream-side surface portion, the first upstream-side surface portion being connected to the first surface portion and located on an upstream side in a leaking direction in which the lubricant leaks, and the second upstream-side surface portion being connected to the second surface portion and located on an upstream side in the leaking direction,
• wherein each of the oil-repellent surfaces and the upstream-side oil-repellent surface is provided with surface texturing in which grooves are formed in a prescribed groove array pattern so as to achieve oil repellency;
• the grooves are provided with a groove width and a groove depth so as to achieve oil repellency;
• and
• the groove array pattern is such that the grooves are arrayed at spacings so as to achieve oil repellency.