A helical sector gear having a body and a gear segment having a plurality of helical teeth. The gear segment has a toothed sector, on which all of the helical teeth are formed, and spacing segments on the opposite circumferential ends of the toothed sector. Each of the spacing segments has a circumferential surface, which is longer than a pitch of the helical teeth, and a radial surface that is formed in a helical manner that conforms to the helix angle of helical teeth. A die set for forming the helical sector gear and a related method are also provided.

An intersecting-axes gear type mechanism includes two gears configured to rotate in mesh with each other. Respective axes of rotation of the two gears being disposed in an intersecting-axes manner, and at least one of the gears has teeth each of which includes a tooth trace extending substantially in a radial direction and a radially inner end face. A chamfered portion is formed on a meeting portion where the radially inner end face and a tooth face of the each of the teeth meet, so as to extend over an overall length of the meeting portion. At least an entirety of an area where the chamfered portion and the radially inner end face meet and an entirety of an area where the chamfered portion and the tooth face meet are each composed of a curved surface in overall length.

The present invention relates to a harmonic gear device in which a first similarity curve obtained by similarly transforming a reference curve representing a moving locus of an external tooth with respect to an internal tooth in a non-deflected state and a second similarity curve generated by similarly transforming the first similarity curve are used as a criterion for generating a tooth profile, wherein the present invention may provide the harmonic gear device that enlarges a first curve represented by a moving locus of positive deflection located above the apex of the reference curve among the moving loci of positive deflection of the external teeth on the basis of the reference curve to approximate an approximate reference point arranged on the second similarity curve to create a second curve, and uses the second curve as the top of the tooth profile of the external tooth.

The present invention relates to a harmonic gear device in which a first similarity curve obtained by similarly transforming a reference curve representing a moving locus of an external tooth with respect to an internal tooth in a non-deflected state and a second similarity curve generated by similarly transforming the first similarity curve are used as a criterion for generating a tooth profile, wherein the present invention may provide the harmonic gear device that enlarges a first curve represented by a moving locus of positive deflection located above the apex of the reference curve among the moving loci of positive deflection of the external teeth on the basis of the reference curve to approximate an approximate reference point arranged on the second similarity curve to create a second curve, and uses the second curve as the top of the tooth profile of the external tooth.

There is provided a technique capable of increasing support rigidity of a bearing when a support member expands due to moisture absorption. A power transmission device includes: a rotary shaft; a support member disposed outside the rotary shaft in a radial direction; a bearing disposed between the rotary shaft and the support member; and a fitting member fitted to an outer peripheral portion of the support member. The fitting member is made of a material having lower hygroscopicity than hygroscopicity of a material of the support member.

A bearing including a bearing ring having an annular base and a plurality of gear teeth integrally formed with the annular base. Each gear tooth of the plurality of gear teeth includes a first flank surface extending substantially radially from the annular base, a top land surface extending substantially in the axial direction, and a chamfered surface between the top land surface and first flank surface. The chamfered surface includes a first arc with a first radius in a range of 0.1 to 0.15 times the gear module of the bearing ring. The first arc has a point of tangency with the first flank surface. The chamfered surface has length P extending in the radial direction between the point of tangency and the top land surface, and P is in the range of 0.1 to 0.15 times the gear module of the bearing ring.

A vehicle drive device uses a parallel shaft gear reducer (30) in which a gear is composed of helical gear, as a speed reducer part (B) that decelerates and outputs a rotation of an electric motor part (A). In the vehicle drive device, of meshing parts of the gears formed in the speed reducer part (B), two gears form a meshing part in which the amount of misalignment that occurs between the tooth surfaces of the two gears meshing with each other is different during driving and during coasting of a vehicle. A first tooth surface (S1) meshing with a mating tooth surface during driving is subjected to tooth surface modification, and a second tooth surface (S2) meshing with a mating tooth surface during coasting is subjected to tooth surface modification of an amount different from an amount of the tooth surface modification to the first tooth surface (S1).

A vehicle drive device uses a parallel shaft gear reducer (30) in which a gear is composed of helical gear, as a speed reducer part (B) that decelerates and outputs a rotation of an electric motor part (A). In the vehicle drive device, of meshing parts of the gears formed in the speed reducer part (B), two gears form a meshing part in which the amount of misalignment that occurs between the tooth surfaces of the two gears meshing with each other is different during driving and during coasting of a vehicle. A first tooth surface (S1) meshing with a mating tooth surface during driving is subjected to tooth surface modification, and a second tooth surface (S2) meshing with a mating tooth surface during coasting is subjected to tooth surface modification of an amount different from an amount of the tooth surface modification to the first tooth surface (S1).

A differential gear mechanism in which when a plurality of contact lines between a gear tooth and a pinion tooth is defined on either a tooth surface of the gear tooth of a crown gear or a tooth surface of the pinion tooth of a pinion gear at a predetermined angle around an axis of the pinion gear, and the plurality of contact lines and a center line of a pinion tooth bottom surface of the pinion gear are projected onto a plane, including an axis of a pair of the crown gears, around the axis of the pinion gear, the center line of the pinion tooth bottom surface projected onto the plane includes an inclined line passing through a range between two of the contact lines which are selected from the plurality of contact lines projected onto the plane and by which a contact ratio is 1.0 or higher.

A differential gear mechanism in which when a plurality of contact lines between a gear tooth and a pinion tooth is defined on either a tooth surface of the gear tooth of a crown gear or a tooth surface of the pinion tooth of a pinion gear at a predetermined angle around an axis of the pinion gear, and the plurality of contact lines and a center line of a pinion tooth bottom surface of the pinion gear are projected onto a plane, including an axis of a pair of the crown gears, around the axis of the pinion gear, the center line of the pinion tooth bottom surface projected onto the plane includes an inclined line passing through a range between two of the contact lines which are selected from the plurality of contact lines projected onto the plane and by which a contact ratio is 1.0 or higher.