Caged roller assembly and reduction gear unit using the same

A caged roller assembly which comprises:

• a cage including outer and inner members;
• and
• a circumferential array of rollers movably retained by the cage, said circumferential array of the rollers defining a pitch circle diameter and having inscribed and circumscribed circle diameters;
• said outer member being of an annular shape having a diameter greater than the pitch circle diameter of the circumferential array of the rollers and also having pockets defined therein in circumferentially spaced relation to each other;
• said inner member including an annular body of a diameter smaller than the pitch circle diameter of the circumferential array of the rollers and annular collars each formed by bending one of opposite end portions of the annular body so as to extend radially outwardly therefrom, said inner member having pockets defined in the annular body in circumferentially spaced relation to each other;
• said rollers being movably supported by the cage while received in part within the corresponding pockets in the annular body of the outer member and in part within the corresponding pockets in the inner member;
• said outer member having a capability of being deformed to a diameter greater than the circumscribed circle diameter of the circumferential array of the rollers;
• said outer member being provided with a slit therein, creating ends of said outer member opposite to each other;
• and
• said inner member not being provided with a slit therein.

A planetary gear reduction unit, which comprises:

• an internally or externally threaded sun gear;
• a carrier disposed rotatably in a coaxial relation with the sun gear;
• a crankshaft supported rotatably by the carrier and having a plurality of neighboring crank pins positioned eccentrically with an axis of the crankshaft;
• and
• a plurality of planetary gears mounted rotatably on the respective crank pins of the crankshaft through corresponding caged roller assemblies and meshed with the sun gear;
• each of said caged roller assemblies comprising,
• a cage including outer and inner members, and
• a circumferential array of rollers movably retained by the cage, said circumferential array of the rollers defining a pitch circle diameter and having inscribed and circumscribed circle diameters, said rollers being capable of undergoing a rolling motion between the corresponding planetary gear and the corresponding crank pin of the crankshaft;
• each of said outer and inner members having respective annular bodies of diameters greater and smaller than the pitch circle diameter of the circumferential array of the rollers;
• said outer member also having annular collars each formed by bending one of opposite end portions of the annular body of the outer member so as to extend radially inwardly therefrom;
• said outer member having pockets defined in the annular body in circumferentially spaced relation to each other;
• said inner member having pockets defined therein in circumferentially spaced relation to each other;
• said rollers being movably supported by the cage while received in part within the corresponding pockets in the annular body of the outer member and in part within the corresponding pockets in the inner member;
• said inner member having a capability of being deformed to a diameter smaller than the inscribed circle diameter of the circumferential array of the rollers;
• said inner member being provided with a slit therein, creating ends of the inner member opposite to each other;
• and
• said outer member not being provided with a slit therein.

A planetary gear reduction unit, which comprises:

• an internally or externally threaded sun gear;
• a carrier disposed rotatably in a coaxial relation with the sun gear;
• a crankshaft supported rotatably by the carrier and having a plurality of neighboring crank pins positioned eccentrically with an axis of the crankshaft;
• and
• a plurality of planetary gears mounted rotatably on the respective crank pins of the crankshaft through corresponding caged roller assemblies and meshed with the sun gear;
• each of said caged roller assemblies comprising,
• a cage including outer and inner members, and
• a circumferential array of rollers movably retained by the cage, said circumferential array of the rollers defining a pitch circle diameter and having inscribed and circumscribed circle diameters, said rollers being capable of undergoing a rolling motion between the corresponding planetary gear and the corresponding crank pin of the crankshaft;
• each of said outer and inner members having respective annular bodies of diameters greater and smaller than the pitch circle diameter of the circumferential array of the rollers;
• said inner member also having annular collars each formed by bending one of opposite end portions of the annular body of the inner member so as to extend radially outwardly therefrom;
• said inner member having pockets defined in the annular body in circumferentially spaced relation to each other;
• said outer member having pockets defined therein in circumferentially spaced relation to each other;
• said rollers being movably supported by the cage while received in part within the corresponding pockets in the annular body of the outer member and in part within the corresponding pockets in the inner member;
• said outer member having a capability of being deformed to a diameter greater than the circumscribed circle diameter of the circumferential array of the rollers;
• said outer member being provided with a slit therein, creating ends of said outer member opposite to each other;
• and
• said inner member not being provided with a slit therein.

A cage for a caged roller assembly having a circumferential array of rollers, the cage comprising:

• outer and inner members,
• wherein one of the outer and inner members is provided with a slit therein, creating engageable ends opposite to each other,
• the remaining one of the outer and inner members is not provided with a slit therein, and
• the member with the provided slit is elastically deformable to a diameter greater than a circumscribed circle diameter of the circumferential array of rollers if the member is the outer member, and elastically deformable to a diameter smaller than an inscribed circle diameter of the circumferential array of rollers if the member is the inner member.