US 11,841,069 B2
Power transmission device
Akihiro Uchida, Toyohashi (JP); Akuto Sekiguchi, Toyohashi (JP); and Tetsuya Okabe, Toyohashi (JP)
Assigned to Musashi Selmitsu Industry Co., Ltd., Aichi (JP)
Appl. No. 17/617,162
Filed by MUSASHI SEIMITSU INDUSTRY CO., LTD., Toyohashi (JP)
PCT Filed Jun. 26, 2020, PCT No. PCT/JP2020/025282
§ 371(c)(1), (2) Date Dec. 7, 2021,
PCT Pub. No. WO2020/262626, PCT Pub. Date Dec. 30, 2020.
Claims priority of application No. 2019-122190 (JP), filed on Jun. 28, 2019.
Prior Publication US 2022/0260147 A1, Aug. 18, 2022
Int. Cl. F16H 48/40 (2012.01); F16H 48/08 (2006.01); F16H 48/38 (2012.01)
CPC F16H 48/40 (2013.01) [F16H 48/08 (2013.01); F16H 2048/385 (2013.01)] 2 Claims
OG exemplary drawing
 
1. A power transmission device comprising a transmission member that has a radially outward facing flange portion on an outer periphery thereof and is rotatable, and a ring gear that has on an inner periphery thereof a hub portion surrounding the flange portion, an outer peripheral face of the flange portion having at least a first outer peripheral part that extends further inward in an axial direction than a side face, on one side in the axial direction, of the flange portion and that has fitted and welded thereto an inner peripheral face of the hub portion, and a second outer peripheral part that is adjacent to an axially inner end of the first outer peripheral part, an annular cavity part being formed between mutually opposing faces of the second outer peripheral part and the inner peripheral face of the hub portion, an axially inner end of a weld portion between the first outer peripheral part and the hub portion facing the cavity part, and the cavity part extending further at least outward in a radial direction than the weld portion,
wherein an annular groove is recessed in a side face, on said one side in the axial direction, of the hub portion so as to make axial positions of the annular groove and the cavity part partially coincide with each other,
the hub portion is narrowed partway along a part sandwiched between the cavity part and the weld portion and the annular groove when viewed in a cross section transecting the annular groove, and a narrowed portion is set to have a thickness that can alleviate residual stress produced around the weld portion of the flange portion by the force with which the flange portion and the hub portion pull each other in response to thermal shrinkage of the weld portion, and
the narrowed portion has a minimum thickness that is no greater than an axial length of the weld portion.