Planet carrier

Abstract

The invention relates to a planet carrier (1) comprising a first and a second cylindrical disc (2, 2'), which discs are coaxial with a shared axis of rotation (A), and the respective bases of which discs face one another, wherein: the first and the second disc (2, 2') have a plurality of axial outer bores (12, 12'); the outer bores (12, 12') extend in parallel with the axis of rotation (A); the outer bores (12, 12') of the first and the second disc (2, 2') are aligned with one another and the outer bores (12, 12') are designed to accommodate planet bearings for mounting the planetary gears or planetary shafts; spacer elements (14) are provided between the first and the second disc (2, 2'), which spacer elements are designed as elements which are separate from the first and the second disc (2, 2') and are in contact with the first and the second disc (2, 2'); and the spacer elements (14) are designed to maintain a defined spacing between the first and the second disc (2, 2').

Description

[0001] Description

[0002] planet carrier

[0003] The present invention relates to a planetary carrier according to the preamble of claim 1.

[0004] Planet carriers are used in planetary gears, especially precision gears, to support the planets within the planetary gear. The planet carriers can consist of two cylindrical disks with stiffness elements arranged between them. The stiffness elements serve to provide torsional and flexural rigidity to the planet carrier. The stiffness elements form an integral part of one or both disks, also called cheeks or jaws. The disks also contain bores into which planetary bearings can be accommodated to support the planets in the planet carrier.

[0005] Currently known planetary carriers, in which the stiffness elements are an integral part of one or both discs, require complex and expensive manufacturing. The stiffness elements must either be cut out of a material of the planet carrier or discs of the planet carrier, for example by milling, or they must be molded to the material of the discs, for example by welding. Furthermore, the stiffness elements commonly used have an approximately triangular shape, making machining complex and expensive. To ensure precisely defined and correctly adjusted preload by the planet carrier within the planetary gear set, the stiffness elements must also be the correct length. This is achieved by grinding the outer surface of the stiffness elements together with the respective disc.However, this requires complex handling and processing of the planet carrier parts, since bearing seats provided in the discs or already integrated bearing raceways must not be damaged during such a grinding process.

[0006] It is therefore an object of the present invention to provide a planetary carrier which is simple and cost-effective to manufacture.

[0007] This object is achieved by a planetary carrier according to patent claim 1.

[0008] The planet carrier comprises a first and a second cylindrical disk arranged coaxially with a common axis of rotation. The disks are spaced apart from one another and arranged with their respective base surfaces, or cover surfaces or end faces, facing one another. The first and second disks each have a plurality of axial outer bores in their respective base surfaces for supporting planetary gears, with the outer bores running parallel to the axis of rotation. The outer bores of the first and second disks are aligned with one another and are designed to accommodate planetary bearings for supporting the planetary gears or planetary axles.

[0009] Outer rings of the planetary bearings can be inserted into the outer bores. Alternatively, the outer bores can be designed as outer rings for the planetary bearings. In this case, the outer bores serve directly as outer rings, without the need for additional outer rings. The rolling elements of the planetary bearings can roll on the surface of the outer bores, which serve as a raceway, or the surface of the outer bores can serve as a counter surface for a plain bearing. Likewise, the outer bores can serve as the seat of planetary axles, on which the planets then run with their bearings.

[0010] In order to connect the first and second cylindrical disks to one another and at the same time keep them at a distance, spacer elements are provided between the first and second disks. These spacer elements are designed as elements separate from the first and second disks and are in contact with the first and second disks. The spacer elements are designed to maintain a defined distance between the first and second disks. However, the spacer elements not only serve to maintain a defined distance between the first and second disks, but also serve as rigidity elements, as was also provided in previously known planetary carriers. Such rigidity elements support the two disks and, at the same time, ensure torsional and flexural rigidity of the planetary carrier.

[0011] By designing the spacer elements as separate elements, it is thus possible to manufacture the first and second disks, as well as the spacer elements, separately. This enables simple production, as the elements, which preferably have simple geometric shapes—namely the two disks and the spacer elements—can be manufactured separately and only subsequently joined together. At the same time, the functionality of the spacer elements, which corresponds to that of the previously used stiffness elements—namely, providing the planetary carrier with torsional and flexural rigidity, is still provided.

[0012] Since the spacers are manufactured separately from the discs, no bearing seats or integrated bearing raceways, which may be provided in the discs, are affected during the production of the spacers, as was the case with planetary carriers used previously.

[0013] According to one embodiment, the spacer elements are detachably attached to the first and second discs. This attachment can be achieved, for example, by means of adhesive or the like. Alternatively, the spacer elements can be coupled to the first and second discs by means of fastening means. These fastening elements can be screws or bolts or the like, but can also be any other type of clamping mechanism. Preferably, the fastening elements can be passed through the spacer elements and through the discs, thus connecting them to one another. For this purpose, the spacer elements can, for example, have an internal bore, wherein the fastening means extend through the respective internal bore of the spacer elements and corresponding axial bores in the base surfaces of the first and second discs. The bores in the two discs can be through-bores.Alternatively, the holes in one of the discs can be blind holes. Some of the holes in one disc can also be through holes and others can be blind holes, with two corresponding holes in the first and second discs each being a through hole and a blind hole, allowing a fastening element to be inserted through a through hole in one disc, through the corresponding spacer element, and into the blind hole in the other disc. Furthermore, the holes, or some of the holes, can be provided with threads that can interact with the corresponding threads of the fastening elements.

[0014] The fastening elements make it possible to connect the two discs to each other and to the spacers. Furthermore, the fastening elements exert a desired clamping force on the discs and spacers, thereby creating a corresponding planet carrier preload.

[0015] According to a further embodiment, the fastening means are subjected to tensile loads, and the spacer elements are subjected to compressive loads. This creates a defined preload state in the planet carrier, which counteracts operating loads.

[0016] As already explained, the spacer elements, or stiffener elements, reduce the rotation of the two discs relative to each other and increase the stiffness of the planetary carrier. In addition, the coupling of the discs achieves preload through the fastening elements, such as screws, by clamping the discs together via the spacer elements.

[0017] The spacers can be cylindrical. Especially when the planet carrier is used in a planetary gear, where the carrier carries a lower torque, such cylindrical spacers can be used, as these have lower torsional rigidity requirements.

[0018] Such a cylindrical shape has the advantage that the spacers can be easily manufactured, for example, by cutting them from a rod or hollow tube. This enables simple production in large quantities. Instead of cutting the spacers from a rod or hollow tube, they can also be manufactured by extrusion or similar processes. To make the spacers the same length for use in the planetary carrier, several spacers can be clamped together in a machine and ground to the same length.

[0019] The two discs each have a smooth, dimensionally stable surface at least on the mutually facing base surfaces, preferably on both base surfaces. If the spacer elements, manufactured to the same length, are then arranged between the discs, a precisely defined and uniform distance can be achieved between the two discs.

[0020] In another embodiment, the spacer elements can have a polygonal shape, for example a triangular shape, as is also provided for in previously known planetary carriers. Such a polygonal shape, e.g. a triangular shape, has the advantage that more material can be present in the outer region, thereby further increasing the torsional and flexural rigidity of the planetary carrier. In contrast to previously known planetary carriers, however, the planetary carrier proposed here has the advantage, even with a polygonal or polygonal shape of the spacer elements, that the disks and the spacer elements are separate elements and can be manufactured separately, thus enabling simpler and more cost-effective production.

[0021] The spacer elements can be made of various materials, such as metal (e.g., steel, aluminum, etc.), plastic (e.g., polymer), or ceramic. The appropriate material can be selected depending on the application and the associated requirements. For example, ceramic has the advantage of allowing high preloads, as it is a very resilient material. Using plastic, in particular, can reduce the weight of the planet carrier, compared to metal, for example.

[0022] Furthermore, manufacturing the planetary carrier from separate parts has the advantage that different materials can be used for the discs and spacers. The material of the spacers can therefore be selected separately from the material of the discs and can be optimized according to the required functionality. For a planetary carrier used in a planetary gear with high torque, a material such as steel can be selected, which can withstand higher forces. While for a planetary carrier used in a planetary gear in a hot environment, a material such as ceramic can be selected, which can withstand high temperatures.

[0023] The spacers themselves can also be made of different materials, for example, some of the spacers can be made of metal and others of plastic.

[0024] According to a further embodiment, each disc has an outer surface and an inner surface, the inner surface defining a central inner bore, with the outer bores arranged between the inner and outer surfaces. A sun gear of the planetary gear can, for example, be guided through such a central inner bore.

[0025] According to a further embodiment, the spacer elements are arranged between the outer bores, in particular as close as possible to or adjacent to the outer surface. Such an arrangement has the particular advantage that the planet carrier is supported and stiffened by the spacer elements in its outer region, i.e., on the base surface in the direction of the outer surface.

[0026] The planet carrier can have any number of outer bores, e.g., both an even and an odd number. Preferably, a spacer element is always arranged between two outer bores, although other arrangements are also possible, for example, two spacer elements between each two outer bores or two outer bores between each one spacer element. Furthermore, the number of outer bores, and thus the number of planets that can be accommodated, as well as the number of spacer elements, can be scaled as required.

[0027] According to a further embodiment, the planet carrier has additional fastening elements which are designed to couple the first and second disks to one another. The additional fastening elements extend through corresponding bores in the base surfaces of the first and second disks. In particular, the additional fastening elements can be arranged adjacent to or as close as possible to the spacer elements. Such additional fastening elements make it possible to improve the connection between the two disks. Furthermore, such additional fastening elements can also be arranged in a central region around the axis of rotation, in particular within the outer bores. In this way, an additional coupling of the two disks can be achieved in their center, which improves the coupling of the two disks to one another and increases the overall stability.The additional fastening elements can actually be positioned centrally in the middle section. An off-center arrangement, e.g., to compensate for an imbalance, is also possible.

[0028] Furthermore, it is possible to connect the additional fastening elements with spacer elements and to provide not only the fastening elements at the respective positions, but also spacer elements through which the fastening elements run.

[0029] According to a further embodiment, the first and second disks are designed to be identical to one another. This not only simplifies the manufacture of the spacer elements, but also the manufacture of the disks, since only one type of disk needs to be manufactured and these can then be arranged in a mirror image of one another. Furthermore, the spacer elements can be designed to be identical to one another, as already explained above, which also simplifies manufacture. In particular, the individual elements can be produced in large quantities in this way. Furthermore, it is possible to combine different individual elements as required, particularly with regard to material, number of bores, e.g. external bores, etc. The same spacer elements can thus be combined with different disks in order to produce different types of planetary carriers.

[0030] Thus, the planet carrier described here can be used for any type of planetary gear unit in which planets are to be guided and supported in planetary bearings within a planet carrier, or in which planetary axles are to be guided through the planet carrier or pressed into it. Such a planet carrier can be used in a planetary gear unit with a sun gear, in which case the discs have a central inner bore, but can also be used in a planetary gear unit without a sun gear, in which case such a central inner bore can be omitted. Furthermore, the number of outer bores, the number of spacers, the material used, the length of the spacers, etc., can be adapted depending on the desired functionality.

[0031] Further advantages and advantageous embodiments are set forth in the description, the drawings, and the claims. In particular, the combinations of features set forth in the description and the drawings are purely exemplary, so the features may also be present individually or in other combinations.

[0032] The invention will be described in more detail below with reference to exemplary embodiments illustrated in the drawings. The exemplary embodiments and the combinations shown in the exemplary embodiments are purely exemplary and are not intended to define the scope of the invention. This scope is defined solely by the appended claims.

[0033] They show:

[0034] Fig. 1 : an exploded view of a planet carrier according to an embodiment;

[0035] Fig. 2: a plan view of a disc of the planet carrier of Fig. 1;

[0036] Fig. 3: a perspective view of a disk of the planet carrier of Fig. 1 according to another embodiment; and

[0037] Fig. 4-6: Top views of a disc of the planet carrier of Fig. 1 according to further embodiments.

[0038] In the following, identical or functionally equivalent elements are identified by the same reference symbols.

[0039] Fig. 1 shows a planet carrier 1 which consists of two cylindrical disks 2, 2'. The first and the second disk 2, 2' have a common axis of rotation A and their base surfaces or cover surfaces face each other. The two disks 2, 2' are preferably identical, which is why only one of the disks 2, 2' is described in detail below. A plan view of one of the disks 2 is shown in Fig. 2. The described features apply analogously to the two disks 2, 2', the reference numerals of the first disk 2 for the second disk 2' being marked with a ".

[0040] The disc 2 has an outer surface 4, which can be connected, for example, to a housing via a main bearing (not shown). Alternatively, the planet carrier 1 can also be used without such a main bearing, i.e., with a floating bearing. In the embodiment shown here, a flange 6 is provided on the outer surface 4. The flange 6 can be used, on the one hand, to connect a drive, for example, a further gear stage or an electric motor, or to connect an output, for example, a further gear stage or a robot arm.

[0041] In the embodiments shown in Figures 1 to 5, the disc 2 also has an inner surface 8 defining a central inner bore 10. A sun gear (not shown) of a planetary gear can be positioned in the inner bore 10.

[0042] On the base surface of the disk 2, in the embodiment shown in Fig. 1 around the inner bore 10, outer bores 12 are arranged. As an example, four outer bores 12 are shown here, but more or fewer outer bores 12 can also be provided. Planetary gears (not shown) can be accommodated in the outer bores 12. For this purpose, planetary bearings (not shown) can be arranged in the outer bores 12, which support the planetary gears in the planet carrier 1. Outer rings of the planetary bearings can be accommodated in the outer bores 12, or the outer bores 12 can themselves serve as outer rings. It should be noted that the two disks 2, 2' and their outer bores 12, 12' are aligned with one another. Furthermore, the outer bores 12 can serve as the seat of axles on which the planetary bearings and the planets are mounted.

[0043] Spacer elements or stiffening elements 14 are provided between the two base surfaces of the discs 2, 2'. These spacer elements 14 serve, on the one hand, to keep the two discs 2, 2' at a distance from each other, and on the other hand, they serve to stiffen the two discs 2, 2' or the entire planet carrier 1. The spacer elements 14 are designed as separate elements. By designing them as separate elements, both the discs 2, 2' and the spacer elements 14 can be manufactured easily, since each element can be manufactured individually. For example, the spacer elements 14 can be designed as cylindrical hollow bodies, as shown in Fig. 1, which can be manufactured, for example, by cutting off a hollow tube. It should be noted, however, that the design as a hollow cylinder, as shown in Fig.1 is only one possibility and the spacer elements 14 can also be designed as a solid cylinder or in another shape.

[0044] The spacer elements 14 can be coupled to the two discs 2, 2' via any type of clamping mechanism. For example, the spacer elements 14 can be connected to the two discs 2, 2' via fastening means (not shown), such as screws or bolts, that extend through bores 16, 16' in the two discs 2, 2'. As shown in Fig. 1 by the dashed line 20, the bores 16, 16' and the bores 18 in the spacer elements 14 are aligned with each other to enable fastening between the discs 2, 2' and the spacer elements 14.

[0045] It should be noted that, although four spacers and four outer bores 12, 12' are shown in Fig. 1, any other number of spacers 14 and bores 12, 12' is possible. Furthermore, the inner bore 10 can be omitted, and the planet carrier 1 can be used in a planetary gear without a sun gear.

[0046] The spacer elements 14 and the corresponding bores 16 in the base surfaces of the discs 2, 2' are preferably arranged in the edge region of the base surfaces. This has the advantage that the two discs 2, 2' can be supported against each other by the spacer elements 14, evenly distributed across their base surfaces. It is particularly preferred if the spacer elements 14 are arranged between the outer bores 12.

[0047] As already explained above, the spacer elements 14 can also have a shape other than the cylindrical shape shown in Figures 1, 2, 4 to 6. As shown in Fig. 3, the spacer elements 14 can, for example, have a triangular shape. The spacer elements 14 are arranged with their wide side 24 towards the outside and with their narrow side 22 towards the inner bore 10. This has the advantage that more material is present in the outer area in order to provide better support there and thus better torsional and flexural rigidity. In Fig. 3, the spacer elements 14 are shown as already connected to the disk 2 and the second disk 2' (not shown) is also connected to the spacer elements 14.

[0048] To provide a better connection between the two panes 2, 2', it is also possible to provide additional fastening means in addition to the spacer elements 14 and the associated fastening means. As shown, for example, in Fig. 4, additional fastening means can be guided through holes 26 provided on both sides of the spacer elements 14 in Fig. 4. This improves the coupling of the two panes 2, 2' and thus leads to a secure connection between the two panes 2, 2'.

[0049] Instead of only providing additional fastening means via the bores 26, further spacer elements 28 can also be provided, as shown in Fig. 5. In this case, the bores 26 are used not only for fastening means, but also additionally for spacer elements 28, wherein, as already described with regard to the spacer elements 14 and the bores 16, the fastening means run through the bores 26 in the two discs 2, 2' and through the spacer elements 28, or a bore through the spacer elements 28.

[0050] An increase in torsional and flexural rigidity can also be achieved by providing additional spacer elements in the center of the disks 2, 2'. As shown in Fig. 6, the planet carrier 1 as a whole can also be provided without an inner bore 10, in which case additional spacer elements 32 can be arranged in the center around the axis of rotation A. As already described with reference to the spacer elements 14 and 28, bores 30 are also provided in the disks 2, 2' and the spacer elements 32 are connected to the two disks 2, 2' via fastening means through the bores 30. Although no inner bore 10 is shown in Fig. 6, it is also possible to provide a smaller inner bore 10 and / or to arrange the spacer elements 32 around the inner bore 10.The planetary carrier described here makes it possible to produce the individual parts of the planetary carrier simply and cost-effectively, while still providing sufficient torsional and flexural rigidity of the planetary carrier for use in planetary gears.

[0051] List of reference symbols

[0052] 1 planet carrier

[0053] 2, 2' disc

[0054] 4, 4' outer surface

[0055] 6, 6' flange

[0056] 8, 8' inner surface

[0057] 10, 10' inner bore

[0058] 12, 12' outer bore

[0059] 14 spacer element

[0060] 16, 16' bore

[0061] 18 through hole

[0062] 20 Alignment line

[0063] 22 narrow side

[0064] 24 wide side

[0065] 26 holes

[0066] 28 spacer elements

[0067] 30 holes

[0068] 32 spacer element

[0069] A axis of rotation

Claims

P a t e n t a n s p r ü c h e Planet carrier Planet carrier (1) comprising a first and a second cylindrical disk (2, 2') arranged coaxially to a common axis of rotation (A), wherein the first and the second disk (2, 2') have a plurality of axial outer bores (12, 12'), wherein the outer bores (12, 12') run parallel to the axis of rotation (A), wherein the outer bores (12, 12') of the first and the second disk (2, 2') are aligned with each other and wherein the outer bores (12, 12') are designed to accommodate planetary bearings for supporting the planet gears or planetary axles, characterized in that spacer elements (14) are provided between the first and the second disk (2, 2'), which are designed as elements separate from the first and the second disk (2, 2') and are in contact with the first and the second disk (2, 2'), wherein the spacer elements (14) are designed toto maintain a defined distance between the first and the second disc (2, 2'). Planetary carrier according to claim 1, wherein the spacer elements (14) are detachably fastened to the first and the second disc (2, 2'), wherein the spacer elements (14) are coupled to the first and the second disc (2, 2') in particular by means of fastening means. Planetary carrier according to claim 2, wherein the fastening elements are loaded in tension and wherein the spacer elements (14) are loaded in compression, whereby a de-, a prestressed state is present in the planet carrier (1), the prestressed state counteracting operating loads and stresses. Planet carrier according to one of the preceding claims, wherein the spacer elements (14) each have an inner bore (18), wherein the fastening means extend through the respective inner bore (18) of the spacer elements (14) and corresponding axial bores (16, 16') in the first and second disks (2, 2'). Planet carrier according to one of the preceding claims, wherein the spacer elements (14) have a cylindrical shape or a polygonal shape, in particular a triangular shape. Planet carrier according to one of the preceding claims, wherein the spacer elements (14) are arranged between the outer bores (12, 12'), in particular adjacent to an outer circumferential surface (4, 4') of the first and second disks (2, 2').Planet carrier according to one of the preceding claims, wherein the planet carrier (1) has additional fastening elements which are designed to couple the first and the second disk (2, 2') to one another, wherein the additional fastening elements extend through corresponding bores (26, 30) in the first and the second disk (2, 2'), wherein the additional fastening elements are arranged in particular adjacent to the spacer elements (14). Planet carrier according to claim 7, wherein the additional fastening elements are arranged in a central region around the axis of rotation (A). Planet carrier according to one of the preceding claims, wherein the spacer elements (14) are made of metal, in particular steel, plastic, in particular polymer, and / or ceramic.Planet carrier according to one of the preceding claims, wherein the first and the second disc (2, 2') are formed identically to one another and / or wherein the spacer elements (14) are formed identically to one another.

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