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

Claim 2:
3. A strain wave gearing, comprising:
an input shaft;
a wave gear mechanism that reduces in speed of rotation of the input shaft and output reduced-speed rotation;
a device housing to support the input shaft in a rotatable state via a bearing;
a lubricant sealing structure that prevents a lubricant from leaking out, from an interior to an exterior of the gearing, through a gap portion formed between an inner peripheral surface potion of the device housing and an outer peripheral surface portion of the input shaft;
an oil seal that is secured to the inner peripheral surface portion of the device housing and that seals the gap portion while slidably being in contact with the outer peripheral surface potion of the input shaft;
an oil-repellent surface that is formed on at least one of the inner peripheral surface portion and the outer peripheral surface portion, and that is positioned at a side of the interior with respect to the oil seal and is apart from the oil seal so as not to come into contact therewith; 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 outer peripheral surface portion and a site on the outer peripheral 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,
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 side of the interior with respect to the first gap portion in which the oil seal is accommodated;
in at least one of the inner peripheral surface portion and the outer peripheral surface portion, the oil-repellant surface is formed on a section extending from a position located at a side further toward the interior than the second gap portion to the second gap portion and is formed on a section forming second gap portion; and
wherein
the first fine grooves extend in a circumferential direction centered on a central axis of the gearing: and
the second fine grooves extend in a direction along the central axis.