Radial bearing and electric motor

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, having at least one harmonic wave type reduction stage, and comprising 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 technology]

[0002] Radial bearings having concentric rings of interleaved rolling elements are used to accommodate radial loads while allowing rotational movement of the rotating parts about a common central axis of the bearing. Gearboxes are also known which reduce the rotational speed of a rotating member at the input of the gearbox to a slower rotation at the output of the gearbox. In this application this is referred to as reduction action.

[0003] Known gearboxes are usually used in combination with external or additional radial bearings, since they cannot or are not suitable for bearing radial loads by themselves. Many technical applications require speed reduction operations, but the problem is that known gearboxes in combination with bearings are prohibitively large. One such technical field is robotics, where there is a particular demand for miniaturization and robust and precise rotation reduction. Another technical field in which the present invention can be used is automotive, in particular electric vehicles and electric wheels.

[0004] EP 3135954 A1 discloses a reduction bearing with integrated reduction motion in a radial bearing. The reduction bearing has at least three concentric rings configured as bearing raceways for two concentric rings of rolling elements, so that the three concentric rings can rotate freely relative to one another under radial load. In the extension of the at least three concentric rings, a harmonic wave reduction stage is integrated, which is based on the known harmonic wave reduction principle. The harmonic wave motion is made possible by radial displacement of the rolling elements between the inner and outer circumferential surfaces of a specially designed outer and inner ring.

[0005] More recently, EP 3366937 A1 discloses a ring-shaped reduction bearing with an inner ring, a center ring, an outer ring, a first ring of rolling elements and a second ring of rolling elements, which are axially aligned with each other and are located between the inner ring and the outer ring. The inner ring and the outer ring are configured to have a bearing raceway in the radial direction with respect to both of the two rings of rolling elements, and the reduction bearing is configured to transmit a wave-shaped reduction movement between the center ring and either the inner ring or the outer ring via an axial displacement of at least one of the rolling elements of the two rings of rolling elements. Some of the bearings disclosed in EP 3366937 A1 have radial-axial bearing properties, which means that they act as radial bearings and at the same time as axial bearings. Summary of the Invention

[0006] The object of the present invention is to improve upon these known bearings, thereby providing a more compact bearing with speed reduction and radial bearing properties.

[0007] In a first aspect of the invention, the object is to provide a radial bearing having a cylindrical configuration around a central axis, comprising at least one harmonic wave type reduction stage, comprising three or more rings and a first ring-shaped arrangement of rolling elements, each of which is centred on the central axis, the three or more rings being arranged such that the ring-shaped arrangement of rolling elements is a) the innermost ring has raceways that contact the rolling elements from the radially inner side, the outermost ring has raceways that contact the rolling elements from the radially outer side, and the third ring, and possibly the fourth ring, have raceways that contact the rolling elements from both axial sides, or b) Three or more rings enclose four raceways in contact with the rolling elements in a rectangular box shape, the box shape being oriented diagonally between 0° and 360° with respect to a central axis; This is achieved by a radial axial bearing in which two radially or axially opposed raceways have structures with different spatial frequencies designed to force the rolling elements into a harmonic wave type vibration between the structured raceways and convert the high speed rotation of the ring with the structured raceway having a low spatial frequency into a low speed rotation of the ring with the raceway having a high spatial frequency during operation of the bearing, the ring or one of the rings having raceways oriented perpendicular to the structured raceways has a separator separating adjacent rolling elements from each other, and at least one of the structured raceways is configured to vibrate in a direction perpendicular to the direction of the rolling elements 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 various amounts.

[0008] The solution of replacing one or both of the solid structure raceways with a raceway structured to form an obstacle that contacts the rolling elements off-center allows the structured raceway to be constructed in less space, since the rolling elements protrude or project beyond the obstacle into the ring with the structured raceway and thus share part of the space with the ring. If the movement of the rolling elements, in particular balls, in the vibration direction is prohibited, the raceway may have a vibration curve only on one side. The raceway may also have two vibration curves whose vibrations are mirror images of each other, i.e. with a relative phase shift of 180° to each other, and contact the rolling elements on the opposite side to the central part of the surface of the rolling elements that protrudes beyond the obstacle. Instead of ball-shaped rolling elements, rolling elements of approximately cylindrical shape may be used, in particular with rounded end faces.

[0009] The oscillating nature of the obstacle curve has the effect of pushing the rolling element out in narrower parts of the obstacle and allowing the rolling element to protrude further through the obstacle in wider parts of the obstacle. As the rolling element moves along the obstacle, it is alternately received within and pushed out of the obstacle, thereby exhibiting an oscillatory motion perpendicular to the plane spanned by the oscillatory curve. This oscillatory motion of the rolling element will result in a radial vibration if the obstacle is part of a raceway that contacts the rolling element from the radially inward or outward, and will vibrate in the axial direction of the bearing if the raceway with the obstacle is located axially towards the rolling element.

[0010] The fact that the rings of rolling elements are in contact radially and axially on both sides results in the bearing functioning as a radial-axial bearing, capable of withstanding radial and axial forces.

[0011] In a second aspect of the invention, the object of the invention is also achieved by a radial axial bearing having a cylindrical configuration centered on a central axis, which has at least one harmonic wave type reduction stage and comprises three or more rings and a first ring-shaped arrangement of rolling bodies, each centered on the central axis, the three or more rings surrounding the ring-shaped arrangement of rolling bodies such that the innermost ring has a raceway in contact with the rolling bodies from the radial inside, the outermost ring has a raceway in contact with the rolling bodies from the radial outside, and a third ring and possibly a fourth ring have raceways in contact with the rolling bodies from both axial sides, the two radially or axially opposed raceways being designed to impose radial harmonic wave type vibrations on the rolling bodies between the raceways structured, operation of the bearing wherein the ring or one of the rings has a structure with a different spatial frequency and has a track oriented orthogonally to the structured tracks, which converts a high speed rotation of a ring with a track with a low spatial frequency into a low speed rotation of a ring with a track with a high spatial frequency, the ring or one of the rings has a separator separating adjacent rolling elements from each other, in particular wherein at least one of the structured tracks is configured to vibrate in a direction perpendicular to the direction of the rolling elements and form an obstacle with at least one curve that contacts the rolling elements off-center such that the rolling elements partially protrude beyond the obstacle by various amounts, the radial axial bearing being further developed to be a multi-row bearing with two or more rows of rolling elements in one reduction stage, or a multi-stage bearing with two or more reduction stages each with one or more rows of rolling elements.

[0012] Providing two or more rows of rolling elements in one reduction stage enhances the bearing capacity of the bearing and allows smooth deceleration operation under large forces, especially if the two rows of rolling elements are provided with structured raceways with the same deceleration coefficient.

[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 the respective vibrations helps to better distribute the load acting on the bearing and the reduction stage.

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

[0015] In an embodiment, the two opposing structured raceways are radially inner and radially outer contact raceways and the harmonic wave type vibration is a vibration of the rolling elements in the radial direction. In another embodiment, the two opposing structured raceways are axially opposing contact raceways and the harmonic wave type vibration is a vibration of the rolling elements in the axial direction. Both configurations are according to configuration a) of the radial axial bearing and can provide good stability and deceleration. The first option with radially oscillating rolling elements is preferred when an axially compact design is required, while the second option with axially oscillating rolling elements can be designed with a small diameter. Furthermore, it is up to the individual design which ring is used as input, which is used as output or as a fixed ring that is attached to another structure or to a motor. Also, it is design dependent which of the two rings with structured raceways has a structure with a higher vibration frequency. When the rotational speed is to be reduced, the input side will have a ring with fewer peaks or vibrations, the output side will have a ring with a higher number of vibrations or a ring equipped with separators for the rolling elements, and the other rings will be fixed rings.

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

[0017] In a radial bearing embodiment, the rim of the vibratory obstacle that contacts the rolling elements off-center is configured as either: - the opposing edges of the gap between the two parts of each ring, - the edges of each ring, and - Vibrationally bent wire.

[0018] Preferably, the two portions of the ring and / or the vibrationally bent wire are held together by a recess in the ring.

[0019] The gap may exist between two parts of one ring, connected directly to each other or through another ring that holds the two parts together. The gap is defined by two vibration curves with the same frequency in the circumferential direction but opposite in phase, so that the gap opens and closes tightly again simultaneously on both sides.

[0020] Another example of one edge on each ring means that there is only one vibrating edge restricting the movement of the rolling element, and the rolling element is held in any position transverse to the vibration direction which may otherwise change with the progression of the rolling element around the central axis.

[0021] Another example of a wire bent to oscillate, held in place using another ring, provides a simple and cost-effective solution for producing a vibration curve that facilitates the concept of an obstacle with a vibration amplitude.

[0022] In an embodiment, the or one of the rings having raceways oriented orthogonally to the structured raceways has separators that separate adjacent rolling elements from each other.

[0023] In an embodiment, one or more rings with raceways oriented orthogonally to the structured raceways have cylindrical openings that accommodate the rolling bodies so that they can move along the axis of the openings, the walls of the openings constituting the separators and the raceways oriented orthogonally to the structured raceways. The cylindrical openings ensure a firm hold of the rolling bodies, which in the simplest configuration are configured as balls, allowing them to move in the direction of the orientation of the cylindrical openings, but with no or negligible play in all lateral directions. In this case, it is sufficient to provide a vibration curve only on one side of the structured raceways, since the lateral movement of the rolling bodies away from the vibration curve is prevented by the walls of the cylindrical openings. The amplitude of the oscillation of the rolling bodies is thus confined so that they do not protrude out of the cylindrical openings.

[0024] In one embodiment, when the rolling elements vibrate radially, one of the radially inner structured raceway and the radially outer structured raceway is formed by a pair of rings or wires having a radially eccentric profile with one or two peaks, each of which contacts the rolling elements off-center.

[0025] In another embodiment, when the rolling elements oscillate axially, a ring having a radially oscillating curve is constructed from two or more members assembled in a manner fixed against axial displacement within the circumferential openings of one or more rings having orbits perpendicular to the structured orbits.

[0026] In another embodiment, when the rolling elements oscillate in the axial direction, the structured track opposite to the other structured track with a curve oscillating in the radial direction is configured as a surface, the surface being configured as a flat surface with an inclination with respect to a plane perpendicular to the central axis, or as a surface with a wave structure with two or three peaks that provides an axial displacement of the rolling elements during the rotation of the surface about the central axis. The plane inclined with respect to the central axis has one peak in the axial direction. In this case, the wave structure can provide multiple peaks. [Brief description of the drawings]

[0027] Other features of the invention will become apparent from the description of the embodiments according to the invention in the light of the claims and the attached drawings, which can embody individual features or a combination of several features.

[0028] The present invention is described below on the basis of exemplary embodiments, without limiting the general content of the invention, and explicit reference is made to the drawings for the disclosure of all details according to the invention not described in more detail in the text.

[0029] [Figure 1] 1 is a schematic perspective view of a known harmonic wave reduction stage; [Figure 2.1] FIG. 2 is a schematic longitudinal section showing the principal arrangement of the rings of a radial bearing with radial oscillation of the rolling elements; [Figure 2.2] FIG. 2 is a schematic diagram showing the principal arrangement of the rings of a radial bearing with axial oscillation of the rolling elements. [Diagram 3] FIG. 1 is a schematic perspective view showing a first embodiment of a radial bearing reduction stage; [Figure 4] FIG. 11 is a schematic vertical cross-sectional view showing a second embodiment. [Diagram 5] FIG. 13 is a schematic perspective view showing a third embodiment of a radial bearing reduction stage; [Figure 6] FIG. 11 is a schematic vertical cross-sectional view showing a third embodiment. [Figure 7]FIG. 11 is a schematic exploded perspective view showing a fourth embodiment of a radial bearing reduction stage; [Figure 8] FIG. 13 is a schematic exploded vertical cross-sectional view showing a fourth embodiment. [Figure 9] FIG. 11 is a schematic longitudinal sectional view of the fourth embodiment in an assembled state. [Figure 10] FIG. 11 is a schematic perspective view showing a fifth embodiment of a radial bearing reduction stage; [Figure 11] FIG. 13 is a schematic vertical cross-sectional view showing a fifth embodiment. [Figure 12] FIG. 13 is a schematic vertical cross-sectional view showing a sixth embodiment. [Figure 13] FIG. 13 is a schematic vertical cross-sectional view showing a seventh embodiment. [Figure 14] FIG. 13 is a schematic vertical cross-sectional view showing an eighth embodiment. [Figure 15] FIG. 13 is a schematic longitudinal sectional view showing a ninth embodiment. [Figure 16] A schematic longitudinal cross-sectional view showing a tenth embodiment of a radial bearing. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] In the drawings, components of the same or similar types or corresponding parts are given the same reference numbers to avoid redundant introduction of items.

[0031] FIG. 1 is a schematic perspective view of a known three-ring harmonic wave type reduction stage of a radial bearing B1, shown here mainly for the purpose of explaining the mechanism of harmonic wave type reduction operation.

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

[0033] When the inner ring R3 is driven in rotation, its elliptical orbit 3 displaces the rolling elements 5 in the radial direction, and each time it passes a peak 7 of the orbit 3, it pushes the rolling elements 5 into the valley of the opposing orbit 4, thereby also inducing a circumferential movement of the rolling elements 5. Since the number of rolling elements 5 is not equal to the number of valleys of the orbit 4, each time it passes a peak 7 of the inner orbit 3, it is forced into the next successive valley of the orbit 4, thereby performing a combination of radial vibration and slow circumferential movement. This causes the entire rolling elements 5 to move in a harmonic wave-like manner. It is typical of a harmonic wave-type reduction orbit that there is a large difference between the number of peaks 7, 9 and valleys of the inner ring R3 and the outer ring R4, respectively, and that the number of rolling elements 5 differs only slightly from the number of peaks 9 and valleys of the ring R4. The reduction ratio of the reduction stage is equal to the ratio of the number of peaks 7, 9 of the innermost ring R3 to the outermost ring R4. In the case shown in Fig. 1, this reduction ratio is 10:1. Instead of two peaks 7, the raceway 3 can have an eccentric shape with only one peak or a small number of peaks, but this number is significantly less than the number of peaks 9 and valleys of the opposing raceway 4, in particular not more than half or a third of that number. The practical limit to the ratio of peaks of the opposing structured raceway is given by the small manufacturable sizes of the rolling elements 5 and the raceway 4.

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

[0035] Harmonic wave type reduction stages with several concentric rings most often have one of two basic design options, which are shown diagrammatically by simplified longitudinal sections in Fig. 2.1 and Fig. 2.2. What is common to both design options is that each rolling element 5 is completely confined without play in the cage in the radial, axial and circumferential directions of the reduction stage, between the raceways 1, 2, 3, 4 and the separator 6. 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 of both rings R1, R2 if they are a common unit. The other raceways 1, 2 of the rings R1, R2 are flat, without structure. The raceways 1, 2 and the separator 6 may be realized as cylindrical openings in the ring R1, as shown in Fig. 1.

[0036] The other two raceways of the rings R3, R4 are structured raceways 3, 4, which impart harmonic wave type vibrations to the rolling element 5 when rotating relative to each other. The two configurations shown in Fig. 2.1 and Fig. 2.2 are different: in Fig. 2.1, the structured raceways 3, 4 of the rings R3, R4 are arranged radially inside and outside the rolling element, and the harmonic wave type vibrations are oriented radially relative to the central axis 12, which is the same as the orientation shown for the bearing B1 in Fig. 1. In contrast, in the configuration shown in Fig. 2.2, the structured raceways 3, 4 of the rings R3, R4 are arranged axially relative to the rolling element 5, which imparts axial vibrations to the rolling element 5 that have no radial component. The radially impinging raceways 1, 2 are not structured.

[0037] FIG. 3 shows a schematic perspective view of a first embodiment of a reduction stage for a radial axial bearing B1. In its basic configuration, it is a radially oscillating reduction stage as shown in FIG. 2.1 and strongly resembles the known reduction stage shown in FIG. 1. The innermost ring R3 again has an elliptical raceway 3 with two peaks 7, while the intermediate ring R1 has a cylindrical opening for the rolling elements 5. The outermost ring R4, however, is essentially a flat ring, divided into two parts with a gap between the two parts. In the circumferential direction of the ring R4, the gap has an oscillating width defined by curves 8 of the opposing sides or rims of the gap, which curves 8 have regularly spaced peaks 9 that narrow the gap width and between which the gap width opens. 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 the ring R4 are formed of gap rims which contact the rolling elements 5 symmetrically and at off-center positions. The rolling elements 5 protrude into the gaps depending on the gap width at the position of the respective rolling element 5. During their circumferential movement, the rolling elements 5 encounter a varying gap width, which causes them to vibrate in the radial direction of the reduction stage. The vibrating structure of the partial rings of the ring R4 is easier to manufacture than the peaks and valleys on the inside of the ring R4 of FIG. 1.

[0039] FIG. 4 is a schematic longitudinal section of a second embodiment of the reduction stage of the radial axial bearing B1, which is a variant of the first embodiment shown in FIG. 3. In the second embodiment of FIG. 4, an intermediate ring constitutes the rings R1, R2, and a separator 6 is a bridge between the two sides. The rolling elements 5 are held between the separator 6 and the raceways 1, 2 so that they can move radially according to the radial contact points. The innermost ring R3 and the outermost ring R4 are divided into two parts, each held by a retaining ring, with gaps of different widths between the two parts. The contact points of the rims of the ring parts define a curve 8, which is designed so that the rolling elements 5 always make contact at four off-center points and protrude into the respective gaps. By opening the gap on one side and narrowing the gap on the other side, the rolling elements move radially. FIG. 4 and most of the following figures show the axial and vertical centerlines of the rolling elements 5 with thin dashed lines. The contact points of a structured track are always off-center relative to the associated axial and / or vertical centerline.

[0040] FIG. 5 is a schematic perspective view of a third embodiment of a radial axial bearing reduction stage with radial harmonic wave type vibration, which differs from the 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 a varying gap as in the second embodiment, the outer ring has two wires 10 bent in the shape of a curve 8. The innermost ring has another variation of the shape of two identical rings offset axially and enclosing a gap between them. The width of the gap is constant, but the thickness of the wires 10 or tracks, respectively, varies in the circumferential direction and presents two peaks 7 opposite each other.

[0041] FIG. 5 does not show the innermost and outermost rings in full, since it would interfere with the view of the guiding wire 10. FIG. 6 is a schematic longitudinal section of the third embodiment of FIG. 5, showing a more complete setup. As can be seen in FIG. 6, the wire 10 in the innermost ring R3 and the wire 10 in the outermost ring R4 are held in place by solid rings R3, R4. Suitable means for connecting the wire 10 to the solid rings R3, R4 include soldering, welding or clamping. Bending the wire 10 and soldering or welding the wire 10 to the solid rings is much less processing than creating the peaks and valleys of the known reduction stage of FIG. 1.

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

[0043] Four rings R1-R4 are again aligned on the central axis 12. From left to right, ring R3 has a surface constituting raceway 3 facing axially inwards. Raceway 3 has one or more crests 7. In the fourth embodiment, raceway 3 has one crest 7, since it is a flat surface inclined obliquely with respect to a plane perpendicular to the central axis 12 of the bearing. Thus, with each rotation of ring R3, the axial position of the contact point of raceway 3 changes so as to oscillate with an amplitude defined by the diameter of raceway 3 and the angle of inclination.

[0044] The outer ring R1 has a cylindrical inner circumferential surface constituting an unstructured raceway 1. As shown in FIG. 9, the inner diameter of the raceway 1 is greater than the outer diameter of the ring R3, which is received inside the ring R1 in the assembled state. The axially opposite ring R2 of the ring R3 is introduced into the ring R1 in such an orientation that the ring of rolling elements 5 faces the raceway 3. Each rolling element 5 is received in a cylindrical opening in the ring R2, the part of the ring R2 separating the cylindrical openings constituting the separator 6. The cylindrical openings are axially oriented so that the rolling elements 5 can move axially in the cylindrical openings. The ring of rolling elements 5 is configured such that the diameter of the outer circumference is equal to the diameter of the inner circumference of the raceway 1 of the ring R1, which stabilizes the radial rotation of the assembly. When the ring R3 comes into contact with the raceway 3, the rolling elements 5 are moved axially in their respective cylindrical openings in the ring R2 with the same amplitude of axial movement as provided by the crest or crests 7 of the raceway 3.

[0045] In the fourth embodiment shown in Figs. 7 to 9, the ring R2 has a second member further axially away from the raceway 3 of the ring R3. This second member is connected by a radially extending central connecting member with the part of the ring R2 with a cylindrical opening for the rolling elements 5, whereby an axial gap is provided between the two members of the ring R2. This axial gap is used to receive the ring R4, which has a radially oscillating shape constituting a curve 8 with more peaks 9 and valleys (in this case nine peaks and valleys respectively). Again, the number of rolling elements 5 is slightly less than the number of peaks 9 and valleys, i.e. eight. Considering that the raceway 3 has one peak, the reduction ratio of the reduction stage shown in Fig. 7 is 9:1.

[0046] The inner rim of the ring R4 constitutes the raceway 4 of the reduction stage. In this embodiment, there is only one curve 8 that contacts the rolling elements off-center. However, any movement transverse to the axial direction is prohibited by the cylindrical opening of the ring R2 that accommodates the rolling elements 5. In this case, there is no gap of varying width, but this arrangement serves the same purpose of limiting the axial movement of the rolling elements 5 in the known manner of harmonic wave type reduction stages. The radial direction of vibration of the curves 8 of the raceway 4 is transverse to the axial direction of vibration of the rolling elements 5. This is the opposite direction to that in the previous embodiment, where the axial direction of vibration of each curve 8 of the raceway 4 is transverse to the radial direction of vibration of the rolling elements 5.

[0047] In the fourth embodiment, the ring R4 is received in the gap between the two members of the ring R2 and is held in axial position inside said gap, so that the ring R4 may comprise two halves or two circumferential members that are assembled after inserting the two members into the axial gap of the ring R2. The assembly of the reduction stage shown in FIG. 7 is shown in a schematic exploded longitudinal section of the fourth embodiment in FIG. 8. An additional member used to fix the assembly is a fixing ring 14 that abuts both the inner faces of the ring R4 and the ring R1.

[0048] In FIG. 9, the reduction stage is shown by a schematic longitudinal section in the assembled state of the fourth embodiment. As can be seen both in FIG. 8 and in FIG. 9, the outer ring R1 has two successive parts separated by a step in the inner diameter of the opening. The opening inside the ring R1 with the smaller diameter faces the ring R3 and is the part that accommodates the rolling elements 5 and brings them into contact with the raceway 1. The part with the larger inner diameter of the ring R1 accommodates the ring R4, which is fixed axially on one side against the step between the two parts of the ring R1 and is clamped on the other side by the fixed ring 14. The ring R2 accommodates the ring R4 in its axial gap without axial play, so that the ring R4 is also fixed axially, since it is fixed axially between the step of the ring R1 and the fixed ring 14. The relative circumferential movement of the rings R2 and R4 is guaranteed.

[0049] 10 and 11 show a schematic perspective view and a schematic longitudinal section of a fifth embodiment of a reduction stage of a radial axial bearing. This fifth embodiment is based on the fourth embodiment shown in Figs. 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 the ring R3.1 is a flat surface inclined at an angle to a plane perpendicular to the central axis 12. Thus, the raceway 3.1 of the ring R3.1 has one crest in the axial direction.

[0050] The ring R1 is fixed to an external structure (not shown), so are the first and second stage rings R4.1, R4.2. The first stage ring R2.1 is driven by the axial movement of the rolling elements 5 driven by the rotation of the ring R3.1 at a reduced rotational speed given by the ratio of the peaks of the rings R4.1 and R3.1. In this embodiment, this reduction ratio is 9:1, meaning that nine revolutions of the ring R3.1 result in one revolution of the ring R2.1.

[0051] The input of the second stage is the ring R3.2, which is connected to the output of the first stage, the ring R2.1, and is driven to rotate. Figure 10 shows that the 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 the ring R2.2. That is, when the ring R3.1 rotates 81 times, the ring R2.2 rotates once. The orbit 3.1 of the ring R3.1 and the orbit 3.2 of R3.2 are flat surfaces inclined at the same oblique angle, and are structurally symmetrical. However, the inclination angles of the orbits 3.1 and 3.2 may be different, as may the number of peaks of the curves 8.1 and 8.2, and in any case may have any phase relationship.

[0052] FIG. 12 is a schematic longitudinal section showing a sixth embodiment of a radial axial reduction bearing B2 constituting a single-stage two-row reduction stage. Each row of the two rows is constructed similarly to the wire 10-based single-stage reduction bearing B1 of FIG. 6. A phase shift between the two rows is again realized to ensure smooth operation of the bearing. In the longitudinal section shown in FIG. 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 phase of the raceways of the rings R3, R4. This phase shift ensures a proper distribution of the load and a smooth operation of the reduction stage of the bearing B2.

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

[0054] FIG. 13 is a schematic longitudinal section of a seventh embodiment, showing a single-stage two-row reduction stage arranged around an electric motor 30 having a stator 32 and a rotor 34. The design principle of the harmonic wave type vibration is the same as that shown in the embodiment of FIGS. 7 to 11 with axial vibration of the rolling elements 5. In this embodiment, the electric motor 30 is centrally located, the innermost ring R2 is attached to the stator 32, and the two rings R3.1, R3.2 are attached to one side of the rotor 34, respectively. This makes the ring R2 fixed together with the stator 32 of the motor 30. The rings R3.1, R3.2 have an inclined track with one crest per revolution, offset by 180° from each other. The two rings R4.1, R4.2 are located axially opposite the rings R3.1, R3.2, respectively, and are fixed relative to the ring R2 by the fixing ring 14. The rings R3.1, R3.2 may be, for example, structured as shown in FIG. 7. However, in the embodiment of FIG. 13, it is the outer rims of the rings R4.1, R4.2 facing the rolling elements 5 that are used as raceways for the harmonic wave type vibration action of the rolling elements 5, instead of the inner rims.

[0055] The outermost ring R1 is provided with separators 6 between circumferentially adjacent rolling elements 5 and is thereby the output of the reduction stage. Again, there is a 180° phase shift between the two rows, ensuring load balance and smooth operation of the reduction stage.

[0056] In FIG. 14, an eighth embodiment is shown by a schematic longitudinal section. The eighth embodiment combines the radial axial bearing B3 of the two-stage radial vibration type reduction stage with reinforcing bearings B5, B6, B7, which provide additional stability and load-bearing capacity. The structured raceways of the rings R3, R4 of this embodiment are constructed by wires 10 in the manner shown in FIG. 5, FIG. 6 and FIG. 12. The motor shaft 15 drives the input 16, which is the ring R3.1 of the first reduction stage. The ring R4 is common to both production 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 a separator 6 between the rolling elements 5, which serves as the output of the first stage and is connected to the input ring R3.2 of the second reduction stage. The ring R1.2 is the output of the second reduction stage and is the harmonic wave type reduction part of the bearing B3.

[0057] FIG. 15 is a schematic longitudinal sectional view showing a ninth embodiment. The ninth embodiment is a radial axial bearing B3 of a two-stage radial vibration type reduction stage, as shown in the fifth embodiment of FIG. 10 and FIG. 11. In the ninth embodiment, the ring R3.1 serves as the input 16, and the stator 32 is attached to the rotor 34 of the electric motor 30 fixed to the ring R1, which is fixed in common to the two reduction stages. The rotating parts are the rotor 32 of the electric motor 30, the ring R3.1 attached to the rotor, the ring R2.1 with the ring R3.1 as the output of the first stage and the input of the second stage, and the ring R2.2 as the output 18 of the second stage.

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

[0059] All listed features, including those taken only from the drawings, and individual features disclosed in combination with other features, are considered to be essential to the invention both alone and in combination. The embodiments according to the invention can be realized by any individual feature or combination of features. Features combined with the expression "especially" or "specially" 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 elements 6 Separator 7 mountains 8,8.1,8.2 curve 9 mountains 10 Wire 12 Center axis 14 Fixing ring 15 Motor shaft 16 Input 18 Output 20 Fixing parts 30 Motor 32 Stator 34 Rotor B1 Bearing B2 multi-row bearing B3 Multi-stage bearing B4 Reinforced bearing B5~B7 Reinforced bearing R1, R1.1, R1.2 Ring R2, R2.1, R2.2 Ring R3, R3.1, R3.2 Ring R4, R4.1, R4.2 Ring

Claims

1. A radial bearing (B1 to B4) having a cylindrical configuration centered on a central axis (12), At least one harmonic wave type reduction stage; a first ring-shaped arrangement of three or more rings (R1-R4) and rolling elements (5) each centered on said central axis (12); The three or more rings (R1 to R4) form a ring-shaped arrangement of the rolling elements (5), a) the innermost ring (R1-R4) has raceways (1-4) which contact the rolling elements (5) from the radial inside, the outermost ring (R1-R4) has raceways (1-4) which contact the rolling elements (5) from the radial outside, and a third ring (R1-R4), possibly a fourth ring (R1-R4), has raceways (1-4) which contact the rolling elements (5) from both axial sides, or b) the three or more rings (R1-R4) have four raceways (1-4) in contact with the rolling elements (5) in a rectangular box shape, the box shape being oriented in an oblique direction between 0° and 360° with respect to the central axis (12); Surrounded by two radially or axially opposed raceways (3, 4) have structures with different spatial frequencies designed to force the rolling elements (5) into a harmonic wave type vibration between the structured raceways (3, 4) and to convert a high speed rotation of a ring (R3) having a structured raceway (3) with a low spatial frequency into a low speed rotation of a ring (R4) having a raceway with a high spatial frequency during operation of the radial axial bearing (B1-B4); the or one of the rings (R1, R2) having the raceways (1, 2) oriented perpendicular to the structured raceways (3, 4) has separators (6) separating adjacent rolling elements (5) from each other, at least one of the structured tracks (3, 4) is configured to oscillate in a direction perpendicular to the direction of the rolling elements (5) and to form an obstacle having at least one curve (8) that contacts the rolling elements (5) off-center such that the rolling elements (5) partially protrude beyond the obstacle by various amounts. Radial axial 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), A radial bearing (B2, B3) according to claim 1.

3. 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) having the same spatial frequency but different phases. A radial bearing (B2, B3) according to claim 2.

4. the two opposing structured tracks (3, 4) being radially inner and radially outer contact tracks (3, 4); The harmonic wave type vibration is a vibration of the rolling element (5) in a radial direction. A radial bearing (B1 to B4) according to claim 1.

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

6. the harmonic wave type vibration is a vibration of the rolling elements (5) in a direction having an oblique angle of option b) relative to the central axis (12); A radial bearing (B1 to B4) according to claim 1.

7. one or more limbs of a vibratory obstacle in off-center contact with said rolling body (5) are configured as one of the opposing edges of a gap between two portions of each of said rings (R1-R4), an edge of each of said rings (R1-R4) and a vibratory bent wire (10); A radial bearing (B1 to B4) according to claim 1.

8. the two parts of the rings (R1-R4) and / or the vibratory bent wire (10) are held together by recesses in the rings (R1-R4), 8. A radial bearing according to claim 7.

9. the or one of the rings (R1, R2) having the raceways (1, 2) oriented perpendicular to the structured raceways (3, 4) has separators (6) separating adjacent rolling elements (5) from each other, A radial bearing (B1 to B4) according to claim 1.

10. 2. A radial axial bearing (B1-B4) according to claim 1, characterized in that one or more of the rings (R1, R2) with the raceways (1, 2) oriented perpendicular to the structured raceways (3, 4) have a cylindrical opening which accommodates the rolling elements (5) so that they can move along the axis of the opening, the walls of which constitute 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 raceway and the radially outer structured raceway is composed of a pair of rings or wires (10) having a radially eccentric profile with one or two peaks, each of which contacts the rolling element (5) off-center. A radial bearing (B1 to B4) according to claim 1.

12. the ring (R4) having a curve (8) that oscillates in a radial direction when the rolling elements (5) oscillate in an axial direction is composed of two or more parts that are assembled in a circumferential opening of one or more rings (R1, R2) having raceways (1, 2) perpendicular to the structured raceways (3, 4) so ​​as to be fixed against axial displacement; A radial bearing (B1 to B4) according to claim 1.

13. a structured raceway (3) facing another structured raceway (4) having a curve (8) that oscillates in the radial direction when the rolling elements (5) oscillate in the axial direction is configured as a surface, the surface having a flat surface with an inclination with respect to a plane perpendicular to the central axis (12) or a wave structure with two or three crests that causes an axial displacement of the rolling elements (5) during a rotation of the surface around the central axis (12); A radial bearing (B1 to B4) according to claim 1.

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

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