Abstract: A worm reducer has: a housing having a wheel housing portion and a worm housing portion; a worm wheel; a worm, a support bearing having an inner ring externally fitted to the tip end portion of the worm and an outer ring; an elastic biasing means elastically biasing the outer ring toward the worm wheel side; and an elastic holding means elastically holding the outer ring from both sides in a direction orthogonal to a biasing direction by the elastic biasing means and to a center axis of the worm housing portion.

Abstract: A method for manufacturing a worm wheel including an inner wheel element including a side plate portion and a tubular eave portion, and an outer wheel element including a wheel tooth portion on an outer circumferential surface thereof, and coupled and fixed to the inner wheel element in a manner of covering a radially outer portion of the side plate portion and the eave portion, the method includes: molding the outer wheel element by disposing a mold around a radially outer portion of the inner wheel element, and feeding the molten synthetic resin from an annular or arc-shaped injection gate toward a pocket portion that is continuous over an entire circumference of a cavity present between an inner surface of the mold and a surface of the inner wheel element and that is present on a radially inner side of the eave portion.

Abstract: A worm reducer has: a housing having a wheel housing portion and a worm housing portion; a worm wheel; a worm, a support bearing having an inner ring externally fitted to the tip end portion of the worm and an outer ring; an elastic biasing means elastically biasing the outer ring toward the worm wheel side; and an elastic holding means elastically holding the outer ring from both sides in a direction orthogonal to a biasing direction by the elastic biasing means and to a center axis of the worm housing portion.

Abstract: An inner wheel element (15a) is embedded in an outer wheel element (16a), such that a continuous range from an inner diameter side circumferential surface configuring an inner surface of a first annular concave part (22), through an outer circumferential surface of the inner wheel element (15a), to an inner diameter side circumferential surface configuring an inner surface of a second annular concave part (38) in a surface of the inner wheel element (15a) is covered over the entire circumference. Accordingly, a structure is achieved which easily secures a holding power of the synthetic resin outer wheel element with respect to the inner wheel element.

Abstract: A first concave-convex part is formed in an outer diameter side circumferential surface of a first annular concave part provided in an axial one-side surface of an inner wheel element, and a second concave-convex part is formed in a bottom surface of a second annular concave part provided in the axial other-side surface of the inner wheel element. An outer circumferential part of the inner wheel element is embedded in an outer wheel element, and synthetic resin forming the outer wheel element partially enters into a plurality of concave parts constituting the first concave-convex part and the second concave-convex part. Thus, a configuration is achieved in which the holding power of a synthetic resin outer wheel can be secured from the metal inner wheel element, and the manufacturing error can be suppressed in the worm wheel tooth part provided in the outer circumferential surface of the outer wheel.

Abstract: An outer wheel element (16a) formed in an annular shape with a synthetic resin and having a worm wheel tooth part (19a) on an outer circumferential surface thereof embeds a radially outer end part of an inner wheel element (15a) formed in an annular shape with a metal. An outer circumferential surface of the inner wheel element (15a), which is radially superimposed with an engaging part between the worm tooth part (19a) and a the worm wheel tooth part serves as a cylindrical surface part (24). This realizes a structure capable of suppressing manufacturing error of the worm wheel tooth part engaging with the worm tooth part.

Abstract: A first concave-convex part is formed in an outer diameter side circumferential surface of a first annular concave part provided in an axial one-side surface of an inner wheel element, and a second concave-convex part is formed in a bottom surface of a second annular concave part provided in the axial other-side surface of the inner wheel element. An outer circumferential part of the inner wheel element is embedded in an outer wheel element, and synthetic resin forming the outer wheel element partially enters into a plurality of concave parts constituting the first concave-convex part and the second concave-convex part. Thus, a configuration is achieved in which the holding power of a synthetic resin outer wheel can be secured from the metal inner wheel element, and the manufacturing error can be suppressed in the worm wheel tooth part provided in the outer circumferential surface of the outer wheel.

Abstract: An outer wheel element (16a) formed in an annular shape with a synthetic resin and having a worm wheel tooth part (19a) on an outer circumferential surface thereof embeds a radially outer end part of an inner wheel element (15a) formed in an annular shape with a metal. An outer circumferential surface of the inner wheel element (15a), which is radially superimposed with an engaging part between the worm tooth part (19a) and a the worm wheel tooth part serves as a cylindrical surface part (24). This realizes a structure capable of suppressing manufacturing error of the worm wheel tooth part engaging with the worm tooth part.

Abstract: An inner wheel element (15a) is embedded in an outer wheel element (16a), such that a continuous range from an inner diameter side circumferential surface configuring an inner surface of a first annular concave part (22), through an outer circumferential surface of the inner wheel element (15a), to an inner diameter side circumferential surface configuring an inner surface of a second annular concave part (38) in a surface of the inner wheel element (15a) is covered over the entire circumference. Accordingly, a structure is achieved which easily secures a holding power of the synthetic resin outer wheel element with respect to the inner wheel element.

Abstract: The invention provides a grease composition for lubricating resins which contains a base oil, a diurea compound represented by formula (I) as a thickener: R1—NHCONH—R2—NHCONH—R3 (I) (wherein R2 represents a bivalent aromatic hydrocarbon group having 6 to 15 carbon atoms, and R1 and R3 each independently represent a straight-chain or branched alkyl group having 8 to 22 carbon atoms), and a chained hydrocarbon polymer having a weight-average molecular weight of 20,000 to 300,000.

Abstract: Provided is a worm wheel formed by combining a metal part and a synthetic resin part to realize a reduction in weight. The worm wheel (4a) is formed by combining an inner wheel element (15a) and an outer wheel element (16a). The inner wheel element (15a) includes a metal core (24) made of metal and formed in an annular shape, and a resin core (25) made of a synthetic resin and formed in an annular shape to surround an outer circumference of the metal core (24). The outer wheel element (16a) is made of a synthetic resin and formed in an annular shape, includes a worm wheel tooth part (19a) on an outer circumferential surface, and surrounds an outer circumference of the resin core (25).

Abstract: The invention provides a grease composition for lubricating resins which contains a base oil, a diurea compound represented by formula (I) as a thickener: R1—NHCONH —R2—NHCONH—R3 (I) (wherein R2 represents a bivalent aromatic hydrocarbon group having 6 to 15 carbon atoms, and R1 and R3 each independently represent a straight-chain or branched alkyl group having 8 to 22 carbon atoms), and a chained hydrocarbon polymer having a weight-average molecular weight of 20,000 to 300,000.

Abstract: Worm wheel construction that is able to sufficiently increase the strength of the connecting portion between a hub 11a and a gear portion 12a, and to maintain sufficient durability even when applied to an electric power steering apparatus that applies a large auxiliary torque, is achieved. A synthetic resin gear portion 12a is molded and formed in the end portion on the outer-diameter side of a metal hub 11a. A first annular concave portion 15 is provided on one surface side in the axial direction of the hub 11a, and a second annular concave portion 22 is provided on the other surface side in the axial direction thereof. Part of the synthetic resin of the gear portion 12a is fed into the portions near the outer diameter of the first annular concave portion 15 and the second annular concave portion 22 to form a first restraining portion 18 and a second restraining portion 23.

Abstract: A core of a worm wheel has an axial end surface formed with a first annular recess, another axial end surface formed with a second annular recess, and a third annular recess formed in a radially outer region of the first annular recess. A rim portion has a first inner circumferential portion fixed to the first annular recess, a second inner circumferential portion fixed to the second annular recess, and a protrusion engaged with the third annular recess.

Abstract: A core of a worm wheel has an axial end surface formed with a first annular recess nad and another axial end surface formed with a second annular recess. An outer circumferential wall surface of a radially outer region of the second annular recess has a tapered surface extending from a bottom surface of the second annular recess to form an obtuse angle relative to the bottom surface, and a third annular recess formed radially outside the tapered surface. A cross-section of the third annular recess is a right-angled triangle having, as two sides, a surface parallel to the bottom surface of the second annular recess and a surface perpendicular to the bottom surface of the second annular recess. A rim portion has a first inner circumferential portion fixed to the first annular recess and a second inner circumferential portion fixed to the second annular recess.

Abstract: A core of a worm wheel has an axial end surface formed with a first annular recess and another axial end surface formed with a second annular recess. A rim portion has a first inner circumferential portion fixed to the first annular recess and a second inner circumferential portion fixed to the second annular recess. An outer circumferential wall surface of the second annular recess extends from a bottom surface of the second annular recess so as to be perpendicular to the bottom surface. A depth of the second annular recess is at least 0.1 mm but not deeper than half of a gate thickness.

Abstract: A power assist apparatus includes an electric motor, a speed reducer, an annular torque sensor, a housing in which the speed reducer and the torque sensor are arranged, and an annular center aligning bracket. The housing includes a first housing element and a second housing element, and one of the first housing element and the second housing element is made of a synthetic resin. The center aligning bracket is fixed to the one of the first housing element and the second housing element by insert molding such that the center aligning bracket is concentric to the one of the first housing element and the second housing element. The first housing element and the second housing element are joined such that the first housing element and the second housing element are engaged with each other in an axial direction of the torque sensor via the center aligning bracket.

Abstract: A core of a worm wheel has an axial end surface formed with a first annular recess, another axial end surface formed with a second annular recess, and a third annular recess formed in a radially outer region of the first annular recess. A rim portion has a first inner circumferential portion fixed to the first annular recess, a second inner circumferential portion fixed to the second annular recess, and a protrusion engaged with the third annular recess.

Abstract: A core of a worm wheel has an axial end surface formed with a first annular recess nad and another axial end surface formed with a second annular recess. A rim portion has a first inner circumferential portion fixed to the first annular recess and a second inner circumferential portion fixed to the second annular recess. An outer circumferential wall surface of the second annular recess extends from a bottom surface of the second annular recess so as to be perpendicular to the bottom surface. A depth of the second annular recess is at least 0.1 mm but not deeper than half of a gate thickness.

Abstract: A core of a worm wheel has an axial end surface formed with a first annular recess nad and another axial end surface formed with a second annular recess. An outer circumferential wall surface of a radially outer region of the second annular recess has a tapered surface extending from a bottom surface of the second annular recess to form an obtuse angle relative to the bottom surface, and a third annular recess formed radially outside the tapered surface. A cross-section of the third annular recess is a right-angled triangle having, as two sides, a surface parallel to the bottom surface of the second annular recess and a surface perpendicular to the bottom surface of the second annular recess. A rim portion has a first inner circumferential portion fixed to the first annular recess and a second inner circumferential portion fixed to the second annular recess.