Patent ID: 11885403
Assignee: HARMONIC DRIVE SYSTEMS INC.
Field: Mechanical elements (Mechanical engineering)
Classification: CPC F | IPC F

Claim 5:
6. An actuator, comprising:
a motor;
a strain wave gearing that is coaxially attached to a mounting flange provided on a front end of the motor;
a motor shaft that penetrates through the mounting flange and extends into an interior of the strain wave gearing;
an input shaft that is coaxially linked with a distal-end portion of the motor shaft inside the strain wave gearing;
a lubricant sealing structure that prevents a lubricant from leaking out, from the strain wave gearing to an interior of the gearing, through a gap portion formed between a first surface portion of an inner peripheral edge part of the mounting flange and portions where the first surface portion faces, the portions including a motor shaft and a second surface portion of the input shaft;
an oil seal that is secured to the first surface portion and that seals the gap portion while slidably being in contact with the second surface potion;
an oil-repellent surface that is formed on at least one of the first surface portion and the second surface portion, and that is positioned further toward the strain wave gearing than is the oil seal so as not to come into contact with the oil seal; and
an oil film formation surface formed on at least one of a distal-end surface portion of the oil seal that comes into contact with the second surface portion and a site on the second surface portion with which the distal-end surface portion comes into contact,
the oil-repellent surface being provided with a surface texture in which first fine grooves having a groove width and a groove depth are formed at prescribed intervals so as to achieve an oil-repelling effect with respect to the lubricant, and
the oil film formation surface being provided with a surface texture in which second fine grooves having a groove width and a groove depth are formed at prescribed intervals so as to achieve an oil film formation effect,
wherein
the gap portion has a first gap portion and a second gap portion, the second gap portion being narrower than the first gap portion;
the second gap portion is located at a site further toward the strain wave gearing than the first gap portion in which the oil seal is accommodated;
in at least one of the first and second surface portions, the oil-repellent surface is formed on a section extending from a position located further toward the strain wave gearing than the second gap portion to the second gap portion and is formed on a section forming the second gap portion; and
wherein
the first fine grooves extend in a circumferential direction centered on a central axis of the actuator; and
the second fine grooves extend in a direction along the central axis.