Abstract: There is provided a differential device including a differential case, side gears, two or more pinion gears, and oil introduction channels. In the differential device (D), an inner surface (Ci) of the differential case (C) includes pinion gear support surfaces (P1, P2) supporting back sides of the respective two or more pinion gears (22), inner surface oil grooves (Gi1, Gi2) provided in the inner surface at positions outward of the respective pinion gear support surfaces and communicating with the oil introduction channels (15, 16), pinion gear lubricating oil grooves (Gp) provided to the pinion gear support surfaces and having one ends opened to the inner surface oil grooves, and discharge channels (O1, O2) making the other ends of the pinion gear lubricating oil grooves communicate with an internal space (17) of the differential case.

Abstract: A differential device includes a differential case having an inner surface with an oil introducing part. The oil introducing part is located between, in an axial direction, a corresponding one side gear support surface and at least a part of a circumferential rim of a window in a circumferential direction. The oil introducing part at least partially protrudes from the inner surface toward a first axial line so as to guide oil such that the oil deviates from a flow direction from the corresponding one side gear support surface to the window along the inner surface and flows around the window.

Abstract: In a power transmission device in which a hub portion of a ring gear is fixed by a weld portion to a flange portion on an outer periphery of a transmission member, a positioning outer peripheral part of an outer periphery of the flange portion has a radial direction positioning face that positions the hub portion in a radial direction with respect to the flange portion, and an axial direction positioning face that positions in an axial direction, a first annular recess part is provided in the positioning outer peripheral part, the first annular recess part alleviating stress caused by a pushing load via which the positioning projecting part pushes the radial direction positioning face due to the hub portion receiving a tensile force inward in the radial direction accompanying thermal shrinkage of the weld portion between a first outer peripheral part and the hub portion.

Abstract: A power transmission device has a hub portion of a ring gear is fixed by a weld portion to a flange portion on an outer periphery of a transmission member, an annular groove that is recessed in the inner side of the axial direction is formed in a side face of the hub portion for making 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 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 alleviates 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.

Abstract: To maintain smooth rotation of a pinion gear, a differential device includes: a differential case including a case main body and a bearing boss protruding from the case main body and rotatably supported about a first rotation axis; a side gear; and a pinion gear. An introduction groove for introducing lubricating oil into the case main body is formed on the bearing boss. An inner surface groove communicating with the introduction groove and extending toward the pinion gear is formed on the case main body. The inner surface groove includes a first groove portion and a second groove portion positioned radially outward from the first groove portion in the radial direction. The shape of at least a part of the first groove portion is a shape over which the lubricating oil is hard to climb during vehicle forward movement as compared with the shape of the second groove portion.

Abstract: To maintain smooth rotation of a pinion gear, a differential device includes: a differential case including a case main body and a bearing boss protruding from the case main body and rotatably supported about a first rotation axis; a side gear; and a pinion gear. An introduction groove for introducing lubricating oil into the case main body is formed on the bearing boss. An inner surface groove communicating with the introduction groove and extending toward the pinion gear is formed on the case main body. The inner surface groove includes a first groove portion and a second groove portion positioned radially outward from the first groove portion in the radial direction. The shape of at least a part of the first groove portion is a shape over which the lubricating oil is hard to climb during vehicle forward movement as compared with the shape of the second groove portion.

Abstract: In a power transmission device in which a hub portion of a ring gear is fixed by a weld portion to a flange portion on an outer periphery of a transmission member, an annular groove that is recessed in the inner side of the axial direction is formed in a side face of the hub portion for making 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 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 alleviates 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.

Abstract: In a power transmission device in which a hub portion of a ring gear is fixed by a weld portion to a flange portion on an outer periphery of a transmission member, a positioning outer peripheral part of an outer periphery of the flange portion has a radial direction positioning face that positions the hub portion in a radial direction with respect to the flange portion, and an axial direction positioning face that positions in an axial direction, a first annular recess part is provided in the positioning outer peripheral part, the first annular recess part alleviating stress caused by a pushing load via which the positioning projecting part pushes the radial direction positioning face due to the hub portion receiving a tensile force inward in the radial direction accompanying thermal shrinkage of the weld portion between a first outer peripheral part and the hub portion.

Abstract: The differential device measuring tool measures an inflow amount of lubricating oil flowing into a housing space through a communication hole during the rotation of a differential case having a case main body in which the housing space and the communication hole are formed and a bearing boss having a through-hole protruding from the case main body and communicating with the housing space. The measuring tool has a collecting portion and a deriving portion. The collecting portion does not interfere with the rotating differential case in the housing space in which the differential gear mechanism is not housed, and has a recess opening and collects the lubricating oil flowing into the housing space through the communication hole. The deriving portion is inserted through the through-hole of the bearing boss and have a deriving flow channel. The deriving flow channel communicates with the recess, and extends to the outside.

Abstract: The differential device measuring tool measures an inflow amount of lubricating oil flowing into a housing space through a communication hole during the rotation of a differential case having a case main body in which the housing space and the communication hole are formed and a bearing boss having a through-hole protruding from the case main body and communicating with the housing space. The measuring tool has a collecting portion and a deriving portion. The collecting portion does not interfere with the rotating differential case in the housing space in which the differential gear mechanism is not housed, and has a recess opening and collects the lubricating oil flowing into the housing space through the communication hole. The deriving portion is inserted through the through-hole of the bearing boss and have a deriving flow channel. The deriving flow channel communicates with the recess, and extends to the outside.