Radial bearings and electric motors

Abstract

A radial axial bearing having a cylindrical configuration about a central axis, with at least one harmonic wave type reduction stage, comprising three or more rings and a first ring-like arrangement of rolling elements, each centered on the central axis, the three or more rings arranging the ring-like arrangement of the rolling elements in such a way that: a) an innermost ring has a raceway contacting the rolling elements from the radially inner side, an outermost ring has a raceway contacting the rolling elements from the radially outer side, and a third ring, and possibly a fourth ring, have raceways contacting the rolling elements from both axial sides; or b) the three or more rings have four raceways contacting the rolling elements in a rectangular box shape. The bearing includes a ring having a box shape encircling the rolling elements such that it is oriented in an oblique direction between 0° and 360° with respect to the central axis, two opposing raceways having structures with different spatial frequencies designed to force the rolling elements to vibrate in a harmonic wave type between the structured raceways and to convert, during operation of the bearing, a high speed rotation of the ring with the structured raceway with a low spatial frequency into a low speed rotation of the ring with the raceway with a high spatial frequency, the ring or one of the raceways having raceways oriented in a direction perpendicular to the structured raceways has a separator separating adjacent rolling elements from each other and is attached to an electric motor. According to the invention, at least one of the structured raceways is configured to vibrate in a direction perpendicular to the direction of the rolling elements and to form an obstacle having at least one curve that contacts the rolling elements off-center such that the rolling elements partially protrude beyond the obstacle by various amounts.

Description

[Technical Field]

[0001] The present invention relates to a radial bearing having a cylindrical shape centered on a central axis, which includes at least one harmonic wave speed reduction stage, three or more rings, and rolling elements each in a first ring-shaped arrangement centered on the central axis, and to an electric motor. [Background Art]

[0002] Radial bearings having concentric rings with rolling elements interposed between the concentric rings are used to bear radial loads while allowing rotational movement of rotating components about the common central axis of the bearing. Gearboxes that reduce the rotational speed of a rotating member at the input of the gearbox to a slower rotation at the output of the gearbox are also known. In the present application, this is referred to as speed reduction operation.

[0003] Generally known gearboxes cannot themselves withstand radial loads or are not suitable for this purpose, so they are usually used in combination with external or additional radial bearings. Many technical applications require speed reduction operation, but generally known gearboxes combined with bearings face the problem of being excessively large. One such technical field is robotics, in which there is a strong demand particularly for miniaturization, robustness, and accurate rotational speed reduction. Another technical field where the present invention can be used is automobiles, particularly electric vehicles and electric wheels.

[0004] European Patent Application Publication No. 3135954 discloses a reduction bearing that integrates reduction action into a radial bearing. This reduction bearing has at least three concentric rings configured as bearing raceways for two concentric rings of rolling elements, and the three concentric rings are able to rotate freely relative to each other while under radial load. This incorporates a harmonic wave reduction stage based on a known harmonic wave reduction principle into an extension of the at least three concentric rings. Harmonic wave action is enabled by the radial displacement of the rolling elements between the inner and outer surfaces of a special structure of the outer and inner rings.

[0005] More recently, European Patent Application Publication No. 3366937 discloses a ring-shaped reduction bearing comprising an inner ring, a central ring, an outer ring, a first ring of rolling elements, and a second ring of rolling elements, with a rotationally symmetric central axis. The first and second rings of rolling elements are axially aligned with each other and located between the inner and outer rings. The inner and outer rings are configured to have radial bearing raceways with respect to both rings of rolling elements, and the reduction bearing is configured to transmit a wave-like reduction motion between the central ring and either the inner or outer ring via the axial displacement of at least one of the two rings of rolling elements. Some of the bearings disclosed in European Patent Application Publication No. 3366937 have radial bearing characteristics, meaning they act as both radial and axial bearings simultaneously. [Overview of the project]

[0006] The object of the present invention is to improve upon these known bearings and thereby provide a smaller bearing that has a reduction function and radial bearing characteristics.

[0007] In a first aspect of the present invention, the object is a radial bearing having a cylindrical configuration centered on a central axis, having at least one harmonic wave type reduction stage, and having three or more rings, each centered on the central axisMultiple ring-shaped arrangement Rolling body and It is equipped with three or more rings that roll body , a) The innermost ring has a track that contacts the rolling element from the radially inward side, the outermost ring has a track that contacts the rolling element from the radially outward side, and the third ring, and possibly the fourth ring, has a track that contacts the rolling element from both axial sides, or b) Three or more rings have four tracks in contact with the rolling element in a rectangular box shape, and that box shape One of its aspects However, it surrounds the central axis, oriented diagonally between 0° and 360°. Two opposing tracks, either radially or axially, force harmonic wave-shaped vibrations between the tracks structured on the rolling element. Radiaxial A bearing has a structure having different spatial frequencies, and one of the rings or rings having tracks oriented perpendicular to the structured tracks, designed to convert the high-speed rotation of a ring having a structured track with a low spatial frequency to the low-speed rotation of a ring having a track with a high spatial frequency during bearing operation, and having separators that separate adjacent rolling elements from each other, and at least one of the structured tracks is a rolling element Radial and circumferential directions Perpendicular to the direction shaft This is achieved by radial bearings configured to vibrate in a directional manner and form an obstacle having at least one curve that contacts the rolling elements off-center, such that the rolling elements partially protrude beyond the obstacle by varying amounts.

[0008] A solution involving replacing one or both of the solid-structured track with a structured track that forms an obstacle that contacts the rolling element off-center allows the structured track to be constructed in less space, as the rolling element jumps or protrudes beyond the obstacle into the ring having the structured track, and thus shares part of the space with the ring. The track may have an vibration curve on only one side, provided that movement of the rolling element, especially the ball, in the direction of vibration is prohibited. Alternatively, the track may have two vibration curves that are mirror images of each other, i.e., have a relative phase difference of 180° from each other, and contact the rolling element on the opposite side of the central portion of the surface of the rolling element that protrudes beyond the obstacle. Instead of ball-shaped rolling elements, substantially cylindrical rolling elements, especially those with rounded end faces, may be used.

[0009] The oscillating nature of the obstacle's curve has the effect of pushing the rolling elements out in the narrower parts of the obstacle and allowing them to protrude further through the obstacle in the wider parts. As the rolling elements move along the obstacle, they are alternately taken in and pushed out of the obstacle, thereby exhibiting an oscillating motion perpendicular to the plane that extends due to the oscillating curve. This oscillating motion of the rolling elements becomes a radial oscillation if the obstacle is part of a track that contacts the rolling elements from the radially inward or outward direction, and the rolling elements oscillate in the axial direction of the bearing if the track with the obstacle is oriented axially toward the rolling elements.

[0010] The fact that the rolling element rings make contact from both the radial inside and outside, as well as from both axial sides, results in the bearing functioning as a radial bearing, capable of withstanding radial and axial forces.

[0011] In a second embodiment of the present invention, the object of the present invention is also achieved by a radial bearing having a cylindrical configuration about a central axis, the bearing having at least one harmonic wave reduction stage, and comprising three or more rings and a first ring-shaped arrangement of rolling elements, each about a central axis, wherein the three or more rings surround the ring-shaped arrangement of rolling elements such that the innermost ring has a raceway in which the rolling elements contact the rolling elements from the radially inward side, the outermost ring has a raceway in which the rolling elements contact the rolling elements from the radially outward side, and the third ring and possibly the fourth ring have raceways in which the rolling elements contact the rolling elements from both axial sides, and the two raceways facing each other radially or axially are designed to force radial harmonic wave vibrations between the structured raceways of the rolling elements, thereby enabling the operation of the bearing The radial bearing further develops to be 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, each having one or more rows of rolling elements. The radial bearing has structures having different spatial frequencies, and the rings or one of them has races oriented perpendicular to the structured races, and a separator that separates adjacent rolling elements from each other, and in particular, at least one of the structured races is configured to form an obstacle having at least one curve that is off-center and in contact with the rolling elements, such that the rolling elements vibrate perpendicular to the direction of the rolling elements and the rolling elements partially protrude beyond the obstacle by varying amounts.

[0012] By providing two or more rows of rolling elements in a single reduction stage, the bearing capacity of the bearing is enhanced, and in particular, if the two rows of rolling elements have structured raceways with the same reduction coefficient, smooth reduction operation under large forces becomes possible.

[0013] In one embodiment of a radial bearing having at least one reduction stage with two or more rows of rolling elements, the obstacles of the two or more rows of rolling elements have vibration curves with the same spatial frequency but different phases. This offset due to the phase shift of each vibration helps to better distribute the load acting on the bearing and the reduction stage.

[0014] Similarly, by providing two or more reduction stages, each having one or more rows of rolling elements, the versatility of such radial bearings can be increased in terms of both bearing strength and achievable reduction ratios. Such multi-row or multi-stage bearings may be equipped with vibration curve limiting obstacles according to the first aspect of the present invention.

[0015] In one embodiment, the two opposing structured raceways are radially inward and radially outward contact raceways, and the harmonic wave vibration is the radial vibration of the rolling element. In another embodiment, the two opposing structured raceways are axially opposing contact raceways, and the harmonic wave vibration is the axial vibration of the rolling element. Both configurations follow the configuration a) of a radial bearing and can provide good stability and deceleration. The first option of radially vibrating the rolling element is preferred when a compact axial design is required, while the second option of axially vibrating the rolling element allows for a smaller diameter design. Furthermore, it is up to the individual design which ring is used as input, output, or as a fixed ring attached to another structure or motor. Also, it is up to the design which of the two rings with structured raceways has the higher vibration frequency structure. To reduce the rotational speed, the input side will have a ring with fewer peaks or vibrations, the output side will have a ring with a higher vibration number or a ring equipped with a separator for the rolling elements, and the other rings will be fixed rings.

[0016] Instead of radial or axial vibrations (i.e., 0°, 90°, 180°, 270°, 360°), another embodiment states that the harmonic wave-type vibration is the vibration of the rolling elements in a direction having an oblique angle of option b) with respect to the central axis, in which case the purely radial or axial vibration of option a) is excluded. Although this configuration of the radial axial bearing according to option b) may be more difficult to manufacture, it is suitable for combining the functions of axial and radial bearings by providing the bearing raceway and vibration at an oblique angle, and for balancing the capabilities of axial and radial bearings according to the design needs, depending on the magnitude of the radial and axial forces that are expected to be absorbed by the bearing.

[0017] In an embodiment of a radial bearing, the rim of a vibrating obstacle that contacts the rolling element off-center is configured as one of the following: - Opposing edges of the gap between the two parts of each ring, - The edges of each ring, and - A wire that has been bent in a vibrating manner.

[0018] Preferably, the two parts of the ring and / or the vibratingly bent wire are held together by the recess of the ring.

[0019] The gap may exist between two parts of a single ring, may be directly connected to each other, or may be connected via another ring that holds the two parts together. The gap is defined by two vibration curves that have the same frequency in the circumferential direction but opposite phases, and the gap opens simultaneously on both sides and then closes tightly again.

[0020] Another example of having one edge on each ring is that there is only one vibrating edge that restricts the movement of the rolling element, and the rolling element is held in any lateral position with respect to the direction of vibration, which otherwise could change as the rolling element progresses around the central axis.

[0021] Another example of an oscillating bent wire held in place using other rings provides a simple and cost-effective solution for producing an oscillation curve that facilitates the concept of an obstacle having an oscillation width.

[0022] In an embodiment, the ring or one of the rings having a race oriented in a direction perpendicular to the structured race comprises a separator that separates adjacent rolling elements from each other.

[0023] In an embodiment, one or more rings having a race oriented in a direction perpendicular to the structured race have a cylindrical opening, the opening accommodates the rolling element so that the rolling element can move along the axis of the opening, and the wall of the opening forms the separator and the race oriented in the direction perpendicular to the structured race. In the simplest configuration, the cylindrical opening ensures firm retention of the rolling element, which is configured as a ball, allowing the rolling element to move in the direction of the orientation of the cylindrical opening, with no or negligible play in all lateral directions. In this case, lateral movement of the rolling element away from the oscillation curve is blocked by the wall of the cylindrical opening, so it is sufficient to provide the oscillation curve on only one side of the structured race. Therefore, the amplitude of rocking movement of the rolling element is maintained such that the rolling element does not protrude from the cylindrical opening.

[0024] In one embodiment, when the rolling element oscillates radially, one of the radially inner structured race and the radially outer structured race is constituted by a pair of rings or wires having a radially eccentric profile with one or two crests, each of which eccentrically contacts the rolling element.

[0025] In another embodiment, when the rolling element oscillates axially, the ring having a radially oscillating curve is constituted by two or more members assembled to be fixed against axial displacement within a circumferential opening of one or more rings having a race perpendicular to the structured race.

[0026] In another embodiment, when the rolling elements vibrate in the axial direction, the structured raceway opposing another structured raceway having a curve that vibrates in the radial direction is configured as a surface, and the surface is configured as a flat surface having an inclination with respect to a plane perpendicular to the central axis, or a surface having a wave structure with two or three peaks that causes axial displacement of the rolling elements during rotation of the surface about the central axis. A plane inclined with respect to the central axis has one peak in the axial direction. In this case, the wave structure can provide a plurality of peaks. [BRIEF DESCRIPTION OF THE DRAWINGS]

[0027] Other features of the present invention will become apparent from the description of embodiments according to the present invention, using the claims and the accompanying drawings. Embodiments according to the present invention can satisfy individual features or a combination of several features.

[0028] The present invention is described below based on exemplary embodiments without limiting the general scope of the present invention, and for the disclosure of all details according to the present invention that are not described in more detail herein, reference is expressly made to the drawings.

[0029] [Figure 1] It is a schematic perspective view of a known harmonic wave reduction stage. [Figure 2.1] It is a schematic longitudinal sectional view showing the main arrangement of a ring of a radial-axial bearing with radial vibration of rolling elements. [Figure 2.2] It is a schematic diagram showing the main arrangement of a ring of a radial-axial bearing with axial vibration of rolling elements. [Figure 3] It is a schematic perspective view showing a first embodiment of a reduction stage for a radial-axial bearing. [Figure 4] It is a schematic longitudinal sectional view showing a second embodiment. [Figure 5] It is a schematic perspective view showing a third embodiment of a reduction stage for a radial-axial bearing. [Figure 6] It is a schematic longitudinal sectional view showing the third embodiment. [Figure 7]This is a schematic exploded perspective view showing a fourth embodiment of a reduction stage for a radial bearing. [Figure 8] This is a schematic exploded longitudinal cross-sectional view showing a fourth embodiment. [Figure 9] This is a schematic longitudinal cross-sectional view showing the fourth embodiment in its assembled state. [Figure 10] This is a schematic perspective view showing a fifth embodiment of the reduction phase of a radial bearing. [Figure 11] This is a schematic longitudinal cross-sectional view showing a fifth embodiment. [Figure 12] This is a schematic longitudinal cross-sectional view showing the sixth embodiment. [Figure 13] This is a schematic longitudinal cross-sectional view showing the seventh embodiment. [Figure 14] This is a schematic longitudinal cross-sectional view showing the eighth embodiment. [Figure 15] This is a schematic longitudinal cross-sectional view showing the ninth embodiment. [Figure 16] This is a schematic longitudinal cross-sectional view showing a tenth embodiment of a radial bearing. [Modes for carrying out the invention]

[0030] In the drawings, identical or similar types of components or their corresponding parts are given the same reference number to avoid redundant entries.

[0031] Figure 1 is a schematic perspective view showing a known three-ring harmonic wave type reduction stage of radial bearing B1, which is shown primarily to illustrate the mechanism of harmonic wave type reduction operation.

[0032] The reduction stage comprises three concentrically arranged rings R1, R3, and R4. The intermediate ring R1 has 19 cylindrical openings, each accommodating one rolling element 5, in this case ball-shaped. The radially outward-facing surface of the inner ring R3 forms an elliptical track 3 with two peaks 7. The radially inward-facing surface of the outer ring R4 forms a track 4 with curves 8 having a larger number (20 each in this case) of peaks 9 and valleys. The precise curvature of the structured tracks 3 and 4 is calculated and designed so that the rolling elements 5 are always in contact with both tracks.

[0033] When the inner ring R3 is driven to rotate, its elliptical orbit 3 displaces the rolling elements 5 radially, pushing them into the valleys of the opposing orbit 4 each time they pass over a peak 7 of orbit 3, thereby inducing circumferential movement of the rolling elements 5. Since the number of rolling elements 5 is not equal to the number of valleys of orbit 4, each time a rolling element 5 passes over a peak 7 of the inner orbit 3, it is forced into the next consecutive valley of orbit 4, thereby executing a combination of radial oscillation and slow circumferential movement. This causes the entire rolling element 5 to move in a harmonic wave pattern. The large difference in the number of peaks 7, 9 and valleys between the inner ring R3 and the outer ring R4, respectively, and the fact that the number of rolling elements 5 is only slightly different from the number of peaks 9 and valleys of ring R4, is typical of a harmonic wave type deceleration orbit. The reduction ratio of the deceleration stage is equal to the ratio of the number of peaks 7 and 9 between the innermost ring R3 and the outermost ring R4. In the case shown in Figure 1, this reduction ratio is 10:1. Instead of two peaks 7, track 3 may have an eccentric shape with only one peak, or a small number of peaks, but this number is considerably less than the number of peaks 9 and valleys of the opposing track 4, in particular less than half or one-third of that number. The practical limit on the ratio of peaks of the opposing structured track is given by the small manufacturable size of the rolling elements 5 and track 4.

[0034] Based on the configuration shown in Figure 1, there are two possible configurations. In both configurations, the innermost ring R3 is rotationally driven by an external drive source, such as the drive shaft of an electric motor. In the first configuration, the outer ring R4 is fixed, and the intermediate ring R1 constitutes the reduction output. In the second configuration, the intermediate ring R3 is fixed, and the outer ring R4 is used as the output. In these two configurations, the rotation direction of the output rings is reversed.

[0035] A harmonic wave reduction stage with multiple concentric rings almost always has one of two basic design options, schematically shown in the simplified longitudinal section views in Figures 2.1 and 2.2. Common to both design options is that each rolling element 5 is completely confined within the cage between the raceways 1, 2, 3, 4 and the separator 6, without any play in the radial, axial, and circumferential directions of the reduction stage. The separator 6 separates adjacent rolling elements 5 from each other in the circumferential direction. The separator 6 is part of the rings R1, R2, or both if rings R1, R2 are a common unit. The other raceways 1, 2 of rings R1, R2 are flat and unstructured. The raceways 1, 2 and the separator 6 may be realized as a cylindrical opening in ring R1, as shown in Figure 1.

[0036] The other two raceways of rings R3 and R4 are structured raceways 3 and 4, which impart harmonic wave-type vibrations to the rolling element 5 as they rotate relative to each other. The two configurations shown in Figures 2.1 and 2.2 are different. In Figure 2.1, the structured raceways 3 and 4 of rings R3 and R4 are positioned radially inward and outward of the rolling element, and the harmonic wave-type vibrations are directed radially with respect to the central axis 12. This is the same orientation as shown in bearing B1 in Figure 1. In contrast, in the configuration shown in Figure 2.2, the structured raceways 3 and 4 of rings R3 and R4 are positioned axially with respect to the rolling element 5, thereby imparting axial vibrations without a radial component to the rolling element 5. The radially abutting raceways 1 and 2 are unstructured.

[0037] Figure 3 is a schematic perspective view showing a first embodiment of a reduction gear of a radial bearing B1. In its basic configuration, it is a radially oscillating reduction gear as shown in Figure 2.1, and is very similar to the known reduction gear shown in Figure 1. The innermost ring R3 again has an elliptical orbit 3 with two peaks 7, and the intermediate ring R1 has a cylindrical opening for the rolling elements 5. However, the outermost ring R4 is basically a flat ring, divided into two parts, with a gap between the two parts. In the circumferential direction of ring R4, the gap has an oscillating width defined by the curves 8 of the opposing sides or rims of the gap, which have regularly spaced peaks 9 that narrow the gap width, and the gap width widens between the peaks 9. The maximum gap width is smaller than the total diameter of the ball-shaped rolling elements 5 so that the ball-shaped rolling elements 5 are held in their respective cages.

[0038] The raceways 4 of ring R4 are formed from gap rims that contact the rolling elements 5 symmetrically and at offset positions from the center. The rolling elements 5 protrude into the gaps according to the gap width at each rolling element 5's position. As the rolling elements 5 move circumferentially, they encounter the changing gap width, thereby causing the rolling elements 5 to vibrate radially in the reduction stage. The vibrating structure of the sub-rings of ring R4 is easier to manufacture than the peaks and valleys on the inside of ring R4 in Figure 1.

[0039] Figure 4 is a schematic longitudinal section view showing a second embodiment of the reduction stage of the radial bearing B1, which is a modification of the first embodiment shown in Figure 3. In the second embodiment of Figure 4, intermediate rings constitute rings R1 and R2, and separator 6 acts as a bridge between the two sides. The rolling elements 5 are held between separator 6 and raceways 1 and 2 so as to be able to move radially according to the radial contact points. The innermost ring R3 and the outermost ring R4 are each divided into two parts held by retaining rings, with gaps of different widths between the two parts. The contact points of the rims of the ring components define a curve 8, and the rolling elements 5 are designed to always contact at four points off-center and protrude into the respective gaps. By widening the gap on one side and narrowing the gap on the other side, the rolling elements move radially. In Figure 4 and most of the following figures, the axial and vertical centerlines of the rolling elements 5 are shown with thin dashed lines. The contact points of structured tracks are always off-center with respect to the associated axial and / or vertical centerlines.

[0040] Figure 5 is a schematic perspective view of a third embodiment of a reduction stage for a radial bearing with radially harmonic wave-type vibration, which differs from previous embodiments in the features defining the contact curves 8 of the innermost ring R3 and the outermost ring R4. Instead of a split ring with varying gaps as in the second embodiment, the outer ring has two wires 10 bent into the shape of the curve 8. The innermost ring has other variations in which two identical rings are offset axially and surround a gap between them. The gap width is constant, but the thickness of the wires 10 or tracks varies circumferentially, each showing two peaks 7 on opposite sides of each other.

[0041] Figure 5 does not fully show the innermost and outermost rings because it would obstruct the display of the guiding wire 10. Figure 6 is a schematic longitudinal section view of the third embodiment of Figure 5, showing a more complete setup. As can be seen from Figure 6, the wire 10 of the innermost ring R3 and the wire 10 of the outermost ring R4 are held in place by the solid rings R3 and R4. Suitable means for connecting the wire 10 to the solid rings R3 and R4 include soldering, welding, or clamping. Bending the wire 10 and soldering or welding the wire 10 to the solid rings is far less work than creating the known crests and valleys of the reduction stages in Figure 1.

[0042] Figure 7 is a schematic exploded perspective view of a fourth embodiment of the reduction stage of a radial bearing, in which the reduction stage vibrates the rolling elements 5 in the axial direction. Figures 8 and 9 are schematic exploded cross-sectional views and longitudinal cross-sectional views of the assembled state, respectively, showing the fourth embodiment of Figure 7. The arrows in Figure 8 indicate the direction of movement of the various components of the reduction stage during assembly.

[0043] The four rings R1 to R4 are again aligned on the central axis 12. From left to right, ring R3 has a surface that forms a raceway 3 facing axially inward. Raceway 3 has one or more peaks 7. In the fourth embodiment, raceway 3 has one peak 7 because it is a flat surface inclined obliquely with respect to a plane perpendicular to the central axis 12 of the bearing. Thus, each time ring R3 rotates, the axial position of the contact point of raceway 3 changes to oscillate with an amplitude defined by the diameter and inclination angle of raceway 3.

[0044] The outer ring R1 has a cylindrical inner surface that constitutes an unstructured raceway 1. As shown in Figure 9, the inner diameter of raceway 1 is larger than the outer diameter of ring R3, and in the assembled state, ring R3 is housed inside ring R1. Ring R2, which is axially opposite to ring R3, is introduced into ring R1 in a orientation such that the rings of the rolling elements 5 face the raceway 3. Each rolling element 5 is housed in a cylindrical opening within ring R2, and the portion separating the cylindrical openings of ring R2 constitutes a separator 6. The cylindrical openings are oriented axially so that the rolling elements 5 can move axially within the cylindrical openings. The ring configuration of the rolling elements 5 is such that the outer diameter is equal to the inner diameter of raceway 1 of ring R1, thereby stabilizing the radial rotation of the assembly. When in contact with raceway 3 of ring R3, the rolling elements 5 are moved axially within each cylindrical opening in ring R2 with the same amplitude of axial movement as provided by one or more peaks 7 of raceway 3.

[0045] In the fourth embodiment shown in Figures 7-9, ring R2 has a second member further axially separated from the track 3 of ring R3. This second member is connected to a portion of ring R2 with a cylindrical opening for the rolling elements 5 by a radially extending central connecting member, thereby creating an axial gap between the two members of ring R2. This axial gap is used to accommodate ring R4, which has a radially oscillating shape that forms a curve 8 with more peaks 9 and valleys (in this case, 9 peaks and 9 valleys each). In this case as well, the number of rolling elements 5 is slightly less than the number of peaks 9 and valleys, i.e., 8. Given that there is one peak in the track 3, the reduction ratio of the reduction stage shown in Figure 7 is 9:1.

[0046] The inner rim of ring R4 constitutes the track 4 of the reduction stage. In this embodiment, there is only one curve 8 that contacts the rolling element off-center. However, lateral movement relative to the axial direction is prohibited by the cylindrical opening of ring R2 that houses the rolling element 5. In this case, there is no gap of varying width, but this configuration serves the same purpose as in known methods of harmonic wave reduction stages, which is to restrict the axial movement of the rolling element 5. The radial direction of the vibration of the curve 8 of track 4 is perpendicular to the axial direction of the vibration of the rolling element 5. This is the opposite direction to that in the previous embodiment, where the axial direction of the vibration of each curve 8 of track 4 is perpendicular to the radial direction of the vibration of the rolling element 5.

[0047] In the fourth embodiment, ring R4 is housed in the gap between the two members of ring R2 and held in a predetermined axial position within that gap, so ring R4 may comprise two halves or two circumferential members that are joined together after the two members are inserted into the axial gap of ring R2. The assembly of the reduction stage shown in Figure 7 is shown in a schematic exploded longitudinal section view of the fourth embodiment in Figure 8. An additional member used to secure the assembly is a fixing ring 14 that abuts against both the inner surfaces of ring R4 and ring R1.

[0048] Figure 9 shows a schematic longitudinal section of the assembled state of the fourth embodiment, illustrating the reduction stage. As seen in both Figures 8 and 9, the outer ring R1 has two continuous portions separated by a step in the inner diameter of the opening. The smaller diameter opening inside ring R1 faces ring R3 and is the portion that houses the rolling elements 5, which contact the raceway 1. The larger diameter portion of ring R1 houses ring R4, which is fixed axially on one side by abutting against the step between the two portions of ring R1 and clamped on the opposite side by a fixing ring 14. Ring R2 houses ring R4 without axial play within its axial gap, so ring R4 is fixed axially between the step in ring R1 and the fixing ring 14, and therefore ring R2 is also fixed axially. Relative circumferential movement of rings R2 and R4 is guaranteed.

[0049] Figures 10 and 11 show schematic perspective and longitudinal section views of a fifth embodiment of the reduction stage of a radial bearing. This fifth embodiment is based on the fourth embodiment shown in Figures 7 to 9. In contrast to the fourth embodiment, the fifth embodiment is an example of a two-stage reduction bearing in which two essentially identical single-row reduction stages are connected in series. The input is provided by a ring R3.1, which is driven by an external motor (not shown) and rotates around a central axis 12. The raceway 3.1 of ring R3.1 is a flat surface inclined obliquely with respect to a plane perpendicular to the central axis 12. Thus, the raceway 3.1 of ring R3.1 has one peak in the axial direction.

[0050] Since ring R1 is fixed to an external structure (not shown), the first and second stage rings R4.1 and R4.2 are also fixed. The first stage ring R2.1 is driven at a reduced rotational speed given by the ratio of the peaks of rings R4.1 and R3.1, by the axial movement of the rolling element 5, which is facilitated by the rotation of ring R3.1. In this embodiment, this reduction ratio is 9:1, meaning that when ring R3.1 rotates 9 times, ring R2.1 rotates 1 time.

[0051] The input to the second stage is ring R3.2, which is connected to and rotationally driven by ring R2.1, the output of the first stage. Figure 10 shows that rings R4.1 and R4.2 have the same spatial orientation. The reduction ratio of the second stage is also 9:1, and its output is ring R2.2. In other words, when ring R3.1 rotates 81 times, ring R2.2 rotates once. The trajectories 3.1 of ring R3.1 and 3.2 of ring R3.2 are flat surfaces inclined at the same oblique angle and have structural symmetry. However, the inclination angles of trajectories 3.1 and 3.2 may be different, as may the number of peaks in curves 8.1 and 8.2, and in either case, they may have any arbitrary phase relationship.

[0052] Figure 12 is a schematic longitudinal cross-sectional view showing a sixth embodiment of a radial reduction bearing B2 comprising a single-stage, two-row reduction stage. Each of the two rows is constructed similarly to the wire 10-based single-stage reduction bearing B1 in Figure 6. A phase shift between the two rows is again realized to ensure smooth operation of the bearing. In the longitudinal cross-section shown in Figure 12, it can be seen that the two rolling elements 5 are in different radial positions due to the phase shift between the two stages, provided by the difference in the phase of the raceways of rings R3 and R4. This phase shift ensures proper load distribution and smooth operation of the reduction stage of bearing B2.

[0053] The radial bearing B2 has reinforcing bearings B5, B6, and B7 to enhance stability and load capacity in both radial and axial directions, and is driven by a motor shaft 15 that inputs radial movement around the central axis 12 to ring R3. The rolling elements 5 are held in their respective openings or cages within the intermediate rings, which are the combined rings R1 and R2. If rings R1 and R2 are fixed to an external structure, the output may be ring R4, or vice versa.

[0054] Figure 13 is a schematic longitudinal cross-sectional view of a seventh embodiment showing a single-stage, two-row reduction gear configured around an electric motor 30 having a stator 32 and a rotor 34. The design principle of harmonic wave vibration is the same as that shown in the embodiments of Figures 7 to 11, which involve axial vibration of the rolling elements 5. In this embodiment, the electric motor 30 is centrally located, with the innermost ring R2 attached to the stator 32, and two rings R3.1 and R3.2 attached to one side of the rotor 34, respectively. This fixes ring R2 together with the stator 32 of the motor 30. Rings R3.1 and R3.2 have inclined tracks with one peak per revolution, offset 180° from each other. Two rings R4.1 and R4.2 are positioned axially opposite to rings R3.1 and R3.2, respectively, and are fixed to ring R2 by a fixing ring 14. Rings R3.1 and R3.2 may have a structure such as that shown in Figure 7, for example. However, in the embodiment shown in Figure 13, the outer rims of the rings R4.1 and R4.2 facing the rolling element 5 are used as the trajectory for the harmonic wave-shaped vibration action of the rolling element 5, instead of the inner rims.

[0055] The outermost ring R1 is equipped with separators 6 between adjacent rolling elements 5 in the circumferential direction, thereby representing the output of the reduction stage. In this case as well, a 180° phase shift between the two rows ensures load balancing and smooth operation of the reduction stage.

[0056] Figure 14 shows an eighth embodiment in a schematic longitudinal section view. The eighth embodiment combines the radial bearing B3 of a two-stage radial vibration type reduction stage with reinforcing bearings B5, B6, B7 that provide further stability and load-bearing capacity. The structured raceways of rings R3, R4 in this embodiment are composed of wires 10 in the manner shown in Figures 5, 6, and 12. The motor shaft 15 drives the input 16, which is ring R3.1 of the first reduction stage. Ring R4 is common to both reduction stages and is fixed to an external structure, for example, the housing of an electric motor (not shown) that drives the motor shaft 15. The first-stage rings R1.1, R2.1 are connected via separators 6 between the rolling elements 5 and function as the output of the first stage, and are connected to the input ring R3.2 of the second reduction stage. Ring R1.2 is the output of the second reduction stage and is the harmonic wave type reduction section of bearing B3.

[0057] Figure 15 is a schematic longitudinal cross-sectional view showing the ninth embodiment. The ninth embodiment is a radial bearing B3 of a two-stage radial vibration type reduction gear, as shown in the fifth embodiment in Figures 10 and 11. In the ninth embodiment, ring R3.1 functions as input 16, and the stator 32 is mounted on the rotor 34 of an electric motor 30, to which ring R1 is fixed, and ring R1 is fixed in common to the two reduction gears. The rotating part is the rotor of the electric motor 30. 34 These are ring R3.1 attached to the rotor, ring R2.1 which uses ring R3.1 as the output of the first stage and the input of the second stage, and ring R2.2 which is the output 18 of the second stage.

[0058] Figure 16 is a schematic longitudinal section showing a tenth embodiment of the radial bearing B4, which is essentially a reduction stage of the bearing B1 of the third embodiment shown in Figure 6, and includes additional reinforcing bearings B5, B6, B7 that provide further stability and bearing load capacity, with the innermost ring R3 functioning as an input 16 driven by a motor shaft 15 of an electric motor (not shown). Ring R4 is a fixed component 20, and ring R1 with separator 6 functions as an output 18, driven by the circumferential motion of rolling elements 5 in radial harmonic wave-type vibrations about a central axis 12.

[0059] All listed characteristics, including those taken solely from the drawings, and any individual characteristics disclosed in combination with other characteristics, are considered important to the present invention, both individually and in combination. Embodiments of the present invention can be realized by individual characteristics or combinations of multiple characteristics. Features combined with the expressions "particularly" or "especially" are treated as preferred embodiments. [Explanation of Symbols]

[0060] 1 orbit 2 orbits 3,3.1,3.2 Bearing raceway 4. Bearing raceway 5 Rolling element 6 Separators 7 mountains 8,8.1,8.2 curve 9 mountains 10 wires 12 Center axis 14 Retaining ring 15 Motor shaft 16 inputs 18 Outputs 20 Fixing parts 30 motors 32 stata 34 rotors B1 bearing B2 multi-row bearing B3 Multi-stage bearing B4 Reinforced bearing B5~B7 Reinforced bearings R1, R1.1, R1.2 Rings R2, R2.1, R2.2 Ring R3, R3.1, R3.2 Rings R4, R4.1, R4.2 Ring

Claims

1. A radial bearing (B1 to B4) having a cylindrical structure centered on a central axis (12), Having at least one harmonic wave type reduction stage, It comprises three or more rings (R1 to R4) and a plurality of rolling elements (5) each arranged in a ring shape around the central axis (12), The three or more rings (R1 to R4) move the rolling element (5) a) The innermost ring (R1 to R4) has a track (1 to 4) that contacts the rolling element (5) from the radially inner side, the outermost ring (R1 to R4) has a track (1 to 4) that contacts the rolling element (5) from the radially outer side, and the third ring (R1 to R4), and possibly the fourth ring (R1 to R4), has a track (1 to 4) that contacts the rolling element (5) from both axial sides, or b) The three or more rings (R1 to R4) have four tracks (1 to 4) in contact with the rolling element (5) in a rectangular box shape, and one of the sides of the box shape is oriented obliquely between 0° and 360° with respect to the central axis (12). Surrounding them in this way, The structure has different spatial frequencies, and is designed such that two radially or axially opposing raceways (3, 4) force harmonic wave-shaped vibrations between the structured raceways (3, 4) on the rolling element (5), and during the operation of the radial bearings (B1-B4), the high-speed rotation of the ring (R3) having the structured raceway (3) having a low spatial frequency is converted to the low-speed rotation of the ring (R4) having the raceway having a high spatial frequency. The ring (R1, R2) or one of the rings having the track (1, 2) oriented in a direction perpendicular to the structured track (3, 4) has a separator (6) that separates adjacent rolling elements (5) from each other. At least one of the structured raceways (3, 4) is configured to vibrate in an axial direction perpendicular to the radial and circumferential directions of the radial bearing, forming an obstacle having at least one curve (8) that is off-center and in contact with the rolling element (5) such that the rolling element (5) partially protrudes beyond the obstacle by varying amounts. Radial bearings (B1 to B4).

2. A multi-row bearing (B2) having two or more rows of rolling elements (5) in one reduction stage, or a multi-stage bearing (B3) having two or more reduction stages, each having one or more rows of rolling elements (5). The radial bearings (B2, B3) according to claim 1.

3. It has at least one reduction stage having two or more rows of rolling elements (5), The obstacles of the two or more rows of rolling elements (5) have vibration curves (8) that have the same spatial frequency but different phases. The radial bearings (B2, B3) according to claim 2.

4. The two opposing structured tracks (3, 4) are radially inward and radially outward contact tracks (3, 4), The harmonic wave-shaped vibration is the vibration of the rolling element (5) in the radial direction. The radial bearings (B1 to B4) according to claim 1.

5. The two opposing structured tracks (3, 4) are axially opposed contact tracks (3, 4), The harmonic wave-shaped vibration is the vibration of the rolling element (5) in the axial direction. The radial bearings (B1 to B4) according to claim 1.

6. The harmonic wave-shaped vibration is the vibration of the rolling element (5) in a direction having an oblique angle of option b) with respect to the central axis (12). The radial bearings (B1 to B4) according to claim 1.

7. One or more rims of the vibrating obstacles that contact the rolling element (5) off-center are configured as opposing edges of the gap between two parts of each ring (R1 to R4), the edges of each ring (R1 to R4), and one of the vibratingly bent wires (10). The radial bearings (B1 to B4) according to claim 1.

8. The two portions of the ring (R1 to R4) and / or the vibratingly bent wire (10) are held together by the retaining ring. The radial bearing according to claim 7.

9. A ring (R1, R2) or one of the rings having the track (1, 2) oriented in a direction perpendicular to the structured track (3, 4) has a separator (6) that separates adjacent rolling elements (5) from each other. The radial bearings (B1 to B4) according to claim 1.

10. The radial bearing (B1 to B4) according to claim 1, wherein one or more rings (R1, R2) having raceways (1, 2) oriented perpendicular to the structured raceways (3, 4) have a cylindrical opening, the opening accommodates the rolling element (5) so as to be able to move along the axis of the opening, and the wall of the opening constitutes a separator (6) and the raceways (1, 2) oriented perpendicular to the structured raceways (3, 4).

11. When the rolling element (5) vibrates radially, one of the radially inner structured track and the radially outer structured track is composed of a pair of rings or wires (10) having a radially eccentric outer shape with one or two peaks, each of which contacts the rolling element (5) off-center. The radial bearings (B1 to B4) according to claim 1.

12. When the rolling element (5) vibrates in the axial direction, the ring (R4) having a radially vibrating curve (8) is composed of two or more parts assembled to be fixed against axial displacement within a circumferential opening of one or more rings (R1, R2) having tracks (1, 2) perpendicular to the structured tracks (3, 4). The radial bearings (B1 to B4) according to claim 1.

13. When the rolling element (5) vibrates in the axial direction, a structured track (3) opposite to another structured track (4) having a radially vibrating curve (8) is configured as a surface, and the surface has a flat surface inclined with respect to a plane perpendicular to the central axis (12), or a wave structure having two or three peaks that cause axial displacement of the rolling element (5) during rotation of the surface around the central axis (12). The radial bearings (B1 to B4) according to claim 1.

14. An electric motor (30) wherein at least radial bearings (B1 to B4) described in any one of claims 1 to 13 are integrated with the electric motor (30) or incorporated into the electric motor (30), the casing of the electric motor (30) forms a support structure for the radial bearings (B1 to B4), and the rotor (34) of the electric motor (30) is connected to or integrated with the input (16) of the radial bearings (B1 to B4) to drive them.

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