Harmonic drive and bearing element for the harmonic drive

Abstract

The invention relates to a harmonic drive and a bearing element for a harmonic drive. The harmonic drive is used for a robot drive and comprises at least one bearing element (1) having an inner ring (2) and an outer ring (3), wherein the inner ring (2) or the outer ring (3) is constructed in sections and wherein two axially adjacent axially inclined needle roller cages (4a, 4b) are arranged spatially between the inner ring (2) and the outer ring (3), in which needle rollers (5) are guided. Furthermore, the bearing element (1) comprises an inner ring (2) and an outer ring (3), wherein the inner ring (2) or the outer ring (3) is constructed in sections and wherein two axially adjacent axially inclined needle roller cages (4a, 4b) are arranged spatially between the inner ring (2) and the outer ring (3), in which needle rollers (5) are guided.

Description

Technical Field

[0001] The invention relates to a harmonic drive for a robot transmission, comprising at least one bearing element with an inner ring and an outer ring, wherein at least one bearing cage is spatially arranged between the inner ring and the outer ring, and rolling bodies are circumferentially guided in the bearing cage. The invention also relates to a bearing element for a harmonic drive. Background Art

[0002] DE 10134191191A1 discloses a transmission unit, which includes an annular housing and a reduction mechanism accommodated in the housing. In addition, the transmission unit includes a rolling bearing for rotatably supporting an output element of the reduction mechanism at the housing, wherein the rolling bearing has an outer ring fixed at the housing, an inner ring present at the output element, and a plurality of rolling bodies. The outer ring is provided with an external thread section on its outer circumference, and an internal thread section matching the external thread section is constructed on the inner circumference of the housing, and the outer ring is screwed to the housing. Summary of the invention

[0003] The object of the present invention is to improve a harmonic drive and a bearing element for a harmonic drive in such a way that they achieve high tilting stiffness and low friction moments while being simple to assemble.

[0004] The harmonic drive for a robot transmission according to the invention comprises at least one bearing element having an inner ring and an outer ring, wherein the inner ring or the outer ring is constructed in sections and wherein two axially adjacent axially inclined needle roller cages are arranged spatially between the inner ring and the outer ring, in which needle rollers are guided. In other words, the bearing element has two axially spaced axially inclined needle roller bearing rows, wherein each axially inclined needle roller bearing row is composed of an axially inclined needle roller cage with needle rollers guided therein. With the aid of a bearing element constructed in this way, large forces can be transmitted in the radial and axial directions, wherein low friction torques and relatively high tilting stiffness can be achieved. In particular, the assembly of the harmonic drive or the bearing element is simplified.

[0005] The bearing element is preferably configured as a driven bearing of a harmonic drive or as part of a driven bearing. Preferably, the bearing element is configured as a double-row self-retaining axially inclined needle roller bearing, wherein a plurality of needle rollers are spatially arranged spaced apart from each other by an axially inclined needle roller cage and roll between the outer circumference of the inner ring and the inner circumference of the outer ring. In other words, two symmetrical rows of inclined needle rollers are axially spaced apart from each other and arranged within the bearing element, wherein the double-row axially inclined needle roller bearing can withstand high radial loads and bidirectional axial loads. The high rigidity of the bearing element is achieved by the double-row axially inclined needle roller bearing.

[0006] The term “segmented inner ring” or “segmented outer ring” is to be understood as meaning that the inner ring is composed of a plurality of inner ring segments or that the outer ring is composed of a plurality of outer ring segments.

[0007] According to one embodiment, the inner ring is composed of a first inner ring segment and a second inner ring segment, wherein the two axially inclined needle roller cages are arranged in an O-type arrangement with respect to one another. In particular, the inner ring segments are axially adjacent and arranged coaxially with respect to one another. In this case, when assembling the bearing element, the axially inclined needle roller cage is first inserted into the one-piece outer ring and then the inner ring segments, i.e. the inner ring halves, are assembled. For example, the inner ring segments can be screwed together.

[0008] According to another embodiment, the outer ring is composed of a first outer ring segment and a second outer ring segment, wherein the two axially inclined needle roller cages are arranged in an X-type arrangement with respect to each other. In particular, the outer ring segments are axially adjacent and arranged coaxially with respect to each other. In this case, when assembling the bearing element, the axially inclined needle roller cage is first inserted into the one-piece inner ring and then the outer ring segments, i.e. the outer ring halves, are assembled. Similar to the O-type arrangement, the outer ring halves can be fixed in their position by tightening.

[0009] In particular, if the bearing element is constructed from a one-piece inner ring and a segmented outer ring, the bearing element must be protected from undesired lubricant leakage due to the centrifugal forces occurring during operation.

[0010] For this purpose, an O-ring is arranged between the first outer ring section and the second outer ring section. The O-ring is, for example, at least partially accommodated in a circumferential groove on the first outer ring section and / or the second outer ring section in order to achieve a sealing effect.

[0011] Alternatively or additionally, a liquid seal is provided between the first outer ring section and the second outer ring section. The liquid seal has the same function as an O-ring, or can additionally assist or improve the sealing function.

[0012] Furthermore, alternatively or additionally, a caulking profile is constructed at the first outer ring segment and / or the second outer ring segment, and the caulking profile abuts against a matching profile correspondingly constructed at the opposite first outer ring segment or the second outer ring segment. The caulking profile extends substantially axially or parallel to the axis of rotation of the bearing element and prevents radial oil leakage between the outer ring segments. If the caulking profile is constructed at the first outer ring segment, the caulking profile abuts against a matching profile formed at the second outer ring segment. Conversely, if the caulking profile is constructed at the second outer ring segment, the caulking profile abuts against a matching profile formed at the first outer ring segment.

[0013] The caulking profile is designed in particular such that it deforms elastically and / or plastically during assembly or during the tightening of the two outer ring segments in order to achieve a sufficient sealing effect at the contact surface between the caulking profile and the mating profile. For this purpose, the caulking profile has, for example, an acute-angled contact tip that deforms elastically and / or plastically during assembly. In other words, the caulking profile is preferably designed to be softer than the mating profile. Therefore, the caulking profile contains a material that has a lower resistance to elastic and / or plastic deformation than the mating profile.

[0014] Alternatively, the mating profile is designed to be softer than the caulking profile. In this case, the mating profile is elastically and / or plastically deformed during assembly or during the tightening of the two outer ring segments in order to achieve a sufficient sealing effect at the contact surface between the caulking profile and the mating profile. For this purpose, the caulking profile, for example, penetrates with its contact tip into the surface of the mating profile, which is elastically and / or plastically deformed during assembly. In addition, the mating profile can already be provided with a recess or groove for accommodating and guiding the caulking profile. In this case, the contact surfaces between the mating profile and the caulking profile are designed to correspond to each other.

[0015] Furthermore, it is conceivable, as an alternative, that both the caulking contour and the fitting contour are embodied in a flexible manner, so that corresponding sealing surfaces for sealing are produced by elastic and / or plastic deformation of the caulking contour and the fitting contour.

[0016] According to an alternative or supplementary design, a lubricant mixture is spatially arranged between the inner ring and the outer ring, and the lubricant mixture is composed of at least a lubricant and a polymer. The lubricant mixture makes it possible to omit additional components or materials for achieving a sealing effect. The lubricant mixture is preferably arranged in the area of ​​the axially inclined needle roller cage, the area of ​​the raceway of the needle roller and / or in the area of ​​the sealing surface where a caulking profile and a matching profile are provided. The lubricant mixture particularly satisfies a dual function. On the one hand, lubrication is improved during the swing operation of the harmonic transmission device, and on the other hand, radial leakage of the lubricant is effectively prevented. The lubricant mixture is also called a lubricant compound, which is usually composed of a porous polymer and a lubricant. Alternatively, grease, lubricating oil or solid lubricant can also be used instead of this lubricant mixture.

[0017] The bearing element for a harmonic drive according to the invention comprises an inner ring and an outer ring, wherein the inner ring or the outer ring is constructed in segments, and wherein two axially adjacent axially inclined needle roller cages are spatially arranged between the inner ring and the outer ring, in which needle rollers are guided. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Other measures for improving the present invention are described in more detail below based on four drawings in combination with the description of three preferred embodiments of the present invention, wherein the same or similar components are provided with the same reference numerals. Herein, it is shown:

[0019] Figure 1 2 shows a simplified schematic sectional view of a bearing element according to the invention for a harmonic drive according to a first embodiment,

[0020] Figure 2 shows a simplified schematic sectional view of a bearing element according to the invention according to a second embodiment,

[0021] Figure 3 Show according to Figure 2 a simplified schematic detail sectional view of a bearing element according to the invention, and

[0022] Figure 4 A greatly simplified schematic detailed sectional view is shown for illustrating two mutually abutting outer ring segments of a bearing element according to the invention according to a third exemplary embodiment. DETAILED DESCRIPTION

[0023] according to Figures 1 to 3 The bearing element 1 for a harmonic drive device (not shown here) according to the present invention comprises an inner ring 2 and an outer ring 3, wherein two axially adjacent axially inclined needle roller cages 4a, 4b are arranged spatially between the inner ring 2 and the outer ring 3, and needle rollers 5 are guided in the axially inclined needle roller cages 4a, 4b. In other words, the bearing element 1 is configured as a double-row axially inclined needle roller bearing and has two rolling element rows 12a, 12b arranged axially offset from each other, wherein the needle rollers 5 of the first rolling element row 12a are arranged symmetrically with respect to the needle rollers 5 of the second rolling element row 12b. In addition, the bearing element 1 has a sealing element 10 for axially sealing the bearing element 1.

[0024] According to Figure 1 In the first embodiment, the outer ring 3 is formed in one piece, wherein the inner ring 2 is formed in sections, i.e., by a first inner ring section 2a and a second inner ring section 2b. In this case, the two axially inclined needle roller cages 4a, 4b are arranged in an O-type arrangement relative to each other in order to simplify the assembly of the bearing element 1 and to increase the tilting stiffness of the bearing element 1. To this end, the axially inclined needle roller cages 4a, 4b are first inserted into the one-piece outer ring, and then the two inner ring sections 2a, 2b are assembled, for example, screwed to each other. In this design of the bearing element 1, it is advantageous that the lubricant does not leak radially outward due to centrifugal forces.

[0025] according to Figures 2 to 4The inner ring 2 is formed in one piece and the outer ring 3 is formed in sections, namely by a first outer ring section 3a and a second outer ring section 3b. In this case, in order to simplify assembly, two axially inclined needle roller cages 4a, 4b are arranged in an X-shaped arrangement with each other.

[0026] According to Figure 2 and Figure 3 In the second embodiment, an O-ring 6 is arranged between the first outer ring segment 3a and the second outer ring segment 3b. The two outer ring segments 3a and 3b respectively have axial guide segments 11a and 11b, which are arranged to overlap each other in the radial direction. In this embodiment, the axial guide segment 11a of the first outer ring segment 3a radially surrounds the axial guide segment 11b of the second outer ring segment 3b. The O-ring is radially arranged between the two guide segments 11a and 11b, and is accommodated at the guide segment 11a of the first outer ring segment 3. Alternatively or in addition, it is conceivable that a liquid seal (not shown here) is provided between the first outer ring segment 3a and the second outer ring segment 3b to replace or improve the sealing effect. In addition, it is conceivable that, instead of the O-ring 6, a press fit is provided between the two guide segments 11a and 11b of the outer ring segments 3a and 3b or between the two outer ring segments 3a and 3b.

[0027] Here, a lubricant mixture 7 consisting of at least a lubricant and a porous polymer is spatially arranged between the inner ring 2 and the outer ring 3. The lubricant mixture (also called lubricant compound) can be used simultaneously with other seals, such as O-rings, or can be used alone without additional seals, thereby reducing manufacturing and maintenance costs. The bearing element 1 lubricated with the lubricant mixture has the same load capacity as a standard greased bearing and operates essentially maintenance-free. The lubricant mixture forms an additional barrier to prevent contamination of the rolling contact between the rolling elements and the raceways. In addition, the lubricant mixture is better integrated into the bearing element 1, thereby reducing the risk of lubricant leakage.

[0028] According to Figure 4In the third embodiment, a caulking profile 8 configured as a contact tip is configured at the second guide section 11b of the second outer ring segment 3b, and the caulking profile abuts against the matching profile 9 configured at the opposite first outer ring segment 3a. Alternatively, the caulking profile 8 can also be configured at the first guide section 11a of the first outer ring segment 3a, and the matching profile 9 is correspondingly configured at the second outer ring segment 3b. Here, the matching profile 9 is configured softer than the caulking profile 8. This means that when the bearing element 1 is assembled, the caulking profile 8 axially enters the matching profile 9, and the matching profile 9 is plastically deformed again to achieve the desired sealing effect. Alternatively, the caulking profile 8 can be configured softer than the matching profile 9, so that the caulking profile 8 is plastically deformed relative to the matching profile 9. In addition, alternatively, the matching profile 9 can be configured complementary to the caulking profile 8. In other words, the matching profile 9 and the caulking profile can have corresponding contact surfaces, which can be formed substantially flat or curved. For example, the mating profile 9 may have a convex curvature and the caulking profile 8 may have a corresponding concave curvature.

[0029] Reference numerals list

[0030] 1 Bearing element

[0031] 2 Inner ring

[0032] 2a, 2b Inner ring section

[0033] 3 Outer ring

[0034] 3a, 3b Outer ring section

[0035] 4a, 4b Axially inclined needle roller cage

[0036] 5 Roller needle

[0037] 6 O-ring

[0038] 7 Lubricant mixture

[0039] 8 Filling profile

[0040] 9 Fitting contour

[0041] 10 Sealing element

[0042] 11a, 11b Guide section

[0043] 12a, 12b Rolling element rows

Claims

1. A harmonic drive for a robot transmission, comprising at least one bearing element (1) having an inner ring (2) and an outer ring (3), wherein: The inner ring (2) or the outer ring (3) is constructed in sections, and two axially adjacent axially inclined needle roller retainers (4a, 4b) are spatially arranged between the inner ring (2) and the outer ring (3), and needle rollers (5) are guided in the axially inclined needle roller retainers, wherein the inner ring (2) is composed of a first inner ring segment (2a) and a second inner ring segment (2b), and is divided in the axial direction from the center of the rotating shaft to the end where the needle rollers are guided, and the two axially inclined needle roller retainers (4a, 4b) are arranged in an O-type arrangement with each other, and the first inner ring segment (2a) and the second inner ring segment (2b) are arranged in an O-type arrangement with each other. a) and the second inner ring segment (2b) respectively have an axial guide segment, and the axial guide segments are arranged to overlap each other in the radial direction, or the outer ring (3) is composed of a first outer ring segment (3a) and a second outer ring segment (3b), and is divided in the axial direction from the end where the needle roller is guided to the outer peripheral end, and the two axially inclined needle roller retainers (4a, 4b) are arranged in an X-shaped arrangement with each other, and the first outer ring segment (3a) and the second outer ring segment (3b) respectively have an axial guide segment (11a, 11b), and the axial guide segments (11a, 11b) are arranged to overlap each other in the radial direction.

2. The harmonic drive device according to claim 1, characterized in that: An O-ring (6) is arranged between the first outer ring section (3a) and the second outer ring section (3b).

3. The harmonic drive device according to claim 1 or 2, characterized in that: A liquid seal is provided between the first outer ring section (3a) and the second outer ring section (3b).

4. The harmonic drive device according to claim 1 or 2, characterized in that: A caulking contour (8) is formed on the first outer ring section (3a) and / or the second outer ring section (3b), which contacts a mating contour (9) formed respectively on the opposite first outer ring section (3a) or second outer ring section (3b).

5. The harmonic drive device according to claim 4, characterized in that: The filling contour (8) is designed to be softer than the fitting contour (9).

6. The harmonic drive device according to claim 4, characterized in that: The fitting contour (9) is designed to be softer than the caulking contour (8).

7. The harmonic drive device according to claim 1, 2, 5 or 6, characterized in that: A lubricant mixture (7) is spatially arranged between the inner ring (2) and the outer ring (3), the lubricant mixture consisting of at least a lubricant and a polymer.

8. A bearing element (1) for a harmonic drive, the bearing element comprising an inner ring (2) and an outer ring (3), wherein: The inner ring (2) or the outer ring (3) is constructed in sections, and two axially adjacent axially inclined needle roller retainers (4a, 4b) are spatially arranged between the inner ring (2) and the outer ring (3), and needle rollers (5) are guided in the axially inclined needle roller retainers, wherein the inner ring (2) is composed of a first inner ring segment (2a) and a second inner ring segment (2b), and is divided in the axial direction from the center of the rotating shaft to the end where the needle rollers are guided, and the two axially inclined needle roller retainers (4a, 4b) are arranged in an O-type arrangement with each other, and the first inner ring segment (2a) and the second inner ring segment (2b) are arranged in an O-type arrangement with each other. a) and the second inner ring segment (2b) respectively have an axial guide segment, and the axial guide segments are arranged to overlap each other in the radial direction, or the outer ring (3) is composed of a first outer ring segment (3a) and a second outer ring segment (3b), and is divided in the axial direction from the end where the needle roller is guided to the outer peripheral end, and the two axially inclined needle roller retainers (4a, 4b) are arranged in an X-shaped arrangement with each other, and the first outer ring segment (3a) and the second outer ring segment (3b) respectively have an axial guide segment (11a, 11b), and the axial guide segments (11a, 11b) are arranged to overlap each other in the radial direction.

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