Radiaxial bearing and electric motor
Radiaxial bearing having a cylindrical configuration centered on a central axis, the bearing having at least one harmonic wave-type reduction stage and including three or more rings and a first ring-shaped arrangement of rolling elements, each being centered on the central axis, the three or more rings enclosing the ring-shaped arrangement of rolling elements such that a) an innermost of the rings has a race in contact with the rolling elements from radially inward, an outermost of the rings has a race in contact with the rolling elements from radially outward, and a third ring, and possibly a fourth ring, has or have a race or races in contact with the rolling elements axially from both sides, or b) the three or more rings have four races contacting the rolling elements in a rectangular box formation, the box formation being oriented at an oblique angle with respect to the central axis of between 0° and 360°, wherein two opposed races have structures with different spatial frequencies that are designed to force the rolling elements into a harmonic-wave type oscillation between the structured races and translating a fast rotation of a ring with a structured race having a low spatial frequency into a slow rotation of a ring having a race with a high spatial frequency during operation of the bearing, wherein the ring or one of the rings that has or have the races that are oriented perpendicular to the structured races has separators separating adjacent rolling elements from one another, and to an electric motor. At least one of the structured races is structured such as to form an obstruction having at least one curve oscillating in a direction perpendicular to the direction of the rolling elements and contacting the rolling elements off-center such that the rolling elements partially protrude beyond the obstruction by varying amounts.
1 . A radiaxial bearing having a cylindrical configuration centered on a central axis, the bearing having at least one reduction stage comprising:
three or more rings; and
a first ring-shaped arrangement of rolling elements;
wherein each of the three or more rings and the first ring-shaped arrangement of rolling elements are centered on the central axis,
wherein the three or more rings enclose the ring-shaped arrangement of rolling elements such that
a) an innermost of the three or more rings has a race in contact with the rolling elements radially inward toward the central axis, an outermost of the three or more rings has a race in contact with the rolling elements radially outward away from the central axis, and a third ring of the three or more rings has a race in contact with the rolling elements axially from both sides, or
b) the three or more rings have four races contacting the rolling elements in a rectangular box formation, the box formation being oriented at an oblique angle with respect to the central axis of between 0° and 360°,
wherein either two radially opposed races or two axially opposed races are provided with structures with different spatial frequencies, respectively, such that the rolling elements are forced into oscillation between the two radially opposed races or the two axially opposed races during operation of the bearing thereby slowing rotation of one of said three or more rings including the race provided with structures having a lower spatial frequency as compared to rotation of another one of said three or more rings including the race provided with structures having a higher spatial frequency,
wherein at least one of said three or more rings has or have races that are oriented perpendicular to the either two radially opposed races or the two axially opposed races that are provided with structures with different spatial frequencies,
wherein the at least one of said three or more rings that has or have races that are oriented perpendicular to the either two radially opposed races or the two axially opposed races that are provided with structures with different spatial frequencies has or have separators separating adjacent rolling elements from one another, and
wherein at least one of the races is provided with a structure that forms an obstruction having at least one curve oscillating in an axial direction perpendicular to a radial direction and a circumferential direction of the bearing thereby contacting the rolling elements off-center such that the rolling elements partially protrude beyond the obstruction by varying amounts.
2 . The radiaxial bearing according to claim 1 , wherein the bearing includes at least four rings, and wherein the at least four rings enclose the ring-shaped arrangement of rolling elements such that an innermost of the at least four rings relative to the central axis has a race in contact with the rolling elements radially inward toward the central axis, an outermost of the at least four rings has a race in contact with the rolling elements radially outward away from the central axis, and at least a third ring and a fourth ring have races in contact with the rolling elements axially from both sides.
3 . The radiaxial bearing according to claim 1 , wherein the bearing is a multi-row bearing having two or more rows of rolling elements in one reduction stage or a multi-stage bearing having two or more reduction stages with one or more rows of rolling elements each.
4 . The radiaxial bearing according to claim 3 , wherein the bearing has at least one reduction stage with two or more rows of rolling elements, and wherein the obstructions for the two or more rows of rolling elements have oscillating curves with the same spatial frequency but different phases.
5 . The radiaxial bearing according to claim 1 , wherein the two opposing races provided with structures with different spatial frequencies are radially inward and radially outward contacting races, and wherein the oscillation is an oscillation of the rolling elements in the radial direction.
6 . The radiaxial bearing according to claim 1 , wherein the two opposing structured races are axially opposed contacting races and the oscillation is an oscillation of the rolling elements in the axial direction.
7 . The radiaxial bearing according to claim 1 , wherein the oscillation is an oscillation of the rolling elements in a direction having the oblique angle with respect to the central axis.
8 . The radiaxial bearing according to claim 1 , wherein a rim or rims of the structure that forms the obstruction having at least one curve oscillating in the direction perpendicular to the direction of rotation of the rolling elements thereby contacting the rolling elements off-center is or are constituted as one or more of:
opposing edges of a gap between two parts of the respective ring;
an edge of the respective ring; and
oscillatingly bent wires.
9 . The radiaxial bearing according to claim 8 , wherein the two parts of the respective ring and/or the oscillatingly bent wires are held together by a holding ring.
10 . The radiaxial bearing according to claim 1 , wherein the ring or one of the rings that has or have the races that are oriented perpendicular to the structured races has cylindrical openings housing the rolling elements such that the rolling elements are able to move along axes of the opening, walls of the openings constituting the separators and the races oriented perpendicular to the structured races.
11 . The radiaxial bearing according to claim 1 , wherein in a case of oscillation of the rolling elements in the radial direction, one of the radially inward structured race and the radially outward structured race is constituted of a pair of rings or wires with a radially eccentric outer shape having one or two peaks, each contacting the rolling elements off-center.
12 . The radiaxial bearing according to claim 1 , wherein in a case of oscillation of the rolling elements in the axial direction, the ring having the curve oscillating in the radial direction is constituted of two or more parts that are assembled in a circumferential opening of the ring or rings having the races perpendicular to the structured races such as to be secured against axial displacement.
13 . The radiaxial bearing according to claim 1 , wherein in a case of oscillation of the rolling elements in the axial direction, a structured race opposing another structured race having the curve oscillating in the radial direction is constituted as a surface with a flat plane having an inclination with respect to a plane perpendicular to the central axis or with a wave structure with two or three peaks resulting in axial displacement of the rolling elements during rotation of the surface around the central axis.
14 . An electric motor, wherein at least one radiaxial bearing according to claim 1 is integrated with or into the electric motor, wherein a casing of the electric motor forms a supporting structure for the radiaxial bearing, and a rotor of the electric motor is drivingly connected to or integral with an input of the radiaxial bearing.