Planet carrier for planetary gears

Abstract

The invention relates to a planet carrier (1) for a planetary gear (2) for transmitting torque from planet gears (3) mounted on the planet carrier (1), comprising a bearing section (4) for mounting the planet gears (3), a toothed section (5) for transmitting a torque introduced into the planet carrier (1) by the planet gears (3), and a sealing section (6) for receiving a sealing ring (7), wherein the planet carrier (1) has a main body (8) made of a single piece of material, which forms the bearing section (4) and the toothed section (5), and a ring component (9) formed separately from the main body (8) and placed on the main body (8), which forms the sealing section (6).

Description

[0001] The invention relates to a planet carrier for a planetary gear set, for transmitting torque from planet gears mounted on the planet carrier, in particular for a (preferably electrically operated) motor vehicle drive train.

[0002] A planetary gear set typically contains several planet gears, which are rotatably mounted on a planet carrier and rotate around a central axis. The planet gears mesh with both a central sun gear and a coaxially arranged ring gear. When the ring gear is stationary, torque applied by the sun gear is transmitted via the rotating planet gears to the planet carrier, which thus transmits torque and serves as the central output element.

[0003] Known planetary carriers are constructed in two parts, with one section, particularly cast, serving as a support for the planetary carriers and an associated section, particularly formed as a (steel) insert, serving as the drive interface. This combination of cast planetary carrier and steel insert represents a robust and solid solution, but is associated with relatively high costs, especially due to the steel insert.

[0004] In contrast, a one-piece, cost-effective planetary carrier made of cast iron cannot be used, as cast iron cannot withstand environmental conditions such as salt spray, does not form a suitable raceway for a radial shaft seal to seal against the housing, has a strong tendency to corrode in the absence of oil lubrication, has relatively thick geometries due to manufacturing processes, and is difficult to coat, among other things, due to corrosion protection.

[0005] The object of the invention is therefore to avoid or at least mitigate the disadvantages of the prior art. In particular, it aims to provide a planetary carrier that meets the requirements of its operating conditions and is also cost-effective to manufacture.

[0006] This problem is solved by a planet carrier having the features of claim 1. Advantageous further developments are the subject of the dependent claims.

[0007] According to the invention, this problem is solved by the planet carrier having a bearing section for supporting the planet gears, a toothed section for transmitting a torque introduced into the planet carrier by the planet gears, and a sealing section, in particular a sealing running surface, for receiving a (radial shaft) sealing ring. The planet carrier has a main body formed from a single piece of material, which forms the bearing section and the toothed section, and a ring component formed separately from the main body and mounted on the main body (firmly connected to the main body), which forms the sealing section. This means that the planet carrier, with the exception of the ring component, is formed in one piece; in particular, the output interface, i.e.,The gear section on the inner circumference of the planet carrier is not designed as a separate output insert (made of steel), but is part of the main body.

[0008] This has the advantage of enabling cost-effective manufacturing of the planet carrier by eliminating the need for a complex and expensively manufactured output insert. Simultaneously, the main body can remain without contact with the environment, as the sealing surfaces that come into contact with the environment are formed (exclusively) by the ring component.

[0009] According to a preferred embodiment, the main body can be formed as a single cast component. In other words, by specifically forming the output interface / gear section as a single piece with the bearing section, the output interface is also cast. Thus, the planet carrier is almost entirely made of cast iron.

[0010] According to one embodiment, the main body can have a substantially tubular (end) section, on the inner circumference of which the toothed section is formed. Preferably, the main body has two parallel-spaced disks that form the bearing section and between which the planet gears can be rotatably received, as well as the hollow body section / tubular section extending from one of the disks along an axis of rotation / longitudinal axis of the planet carrier / planetary gear set.

[0011] Preferably, the tubular section of the main body can be internally stepped. In particular, the tubular section can have a larger inner diameter in a first inner tube section than in a second inner tube section, with the first inner tube section being located closer to the bearing section for the planet gears than the second inner tube section. This means that the inner diameter of the tubular section tapers in a stepped fashion in one direction away from the bearing section. This allows for manufacturability by casting and enables the provision of functional surfaces at different diameters.

[0012] According to a preferred embodiment, the main body can form a (first) bearing raceway on its inner circumferential surface for supporting the planet carrier, in particular on the sun gear. Preferably, the (first) bearing raceway can be formed on the tubular section of the main body, particularly in the region of the first inner tube section.

[0013] Preferably, the tubular section of the main body can be stepped on its outer surface. In particular, the tubular section can have a larger outer diameter in a first outer tube section than in a second outer tube section, with the first outer tube section being located closer to the bearing section for the planet gears than the second outer tube section. This means that the outer diameter of the tubular section tapers in a stepped fashion in one direction away from the bearing section. This allows for manufacturability by casting and enables the provision of functional surfaces at different diameters.

[0014] According to one embodiment, the main body can form a (second) bearing raceway on its outer circumferential surface for supporting the planet carrier, particularly in the gearbox housing. Preferably, the (second) bearing raceway can be formed on the tubular section of the main body, particularly in the area of ​​the first outer tube section.

[0015] Preferably, the bearing raceways are arranged at essentially the same height along the axis of rotation / longitudinal axis. This improves stability.

[0016] According to a preferred embodiment, the main body can form a receiving surface on its outer circumferential surface for receiving the ring component. Preferably, the receiving surface can be formed on the tubular section of the main body, particularly in the region of the second outer tube section.

[0017] Preferably, the tubular section of the main body can have a significantly greater wall thickness (i.e., at least twice as much) in the area of ​​the first outer tube section than in the area of ​​the second outer tube section. This provides sufficient stability in the area of ​​the bearing raceways, while high stability is not required in the area of ​​the receiving surface for the ring component.

[0018] According to a preferred embodiment, the ring component can be designed as a metal ring. This makes it particularly easy to design the ring component without any twisting, which is especially relevant for sealing.

[0019] According to a preferred embodiment, the ring component can have a coating, particularly applied to its outer circumferential surface, and / or be heat-treated. This allows the material properties of the ring component to be further modified and, for example, to be particularly effectively protected against external environmental influences and / or corrosion.

[0020] According to one embodiment, the ring component can have an annular cross-section. Preferably, the annular cross-section is essentially constant over the entire axial / longitudinal extent of the ring component. This means that the ring component preferably has no steps on the outer and inner circumferences or any significant changes in cross-section. Due to its simple shape, the ring component can be manufactured particularly cost-effectively.

[0021] According to a preferred embodiment, the ring component can be pressed onto the main body, in particular onto the tubular section, especially in the area of ​​the second outer tube section. This allows a secure connection between the ring component and the main body to be created in a simple manner.

[0022] According to a preferred embodiment, an outer surface of the ring component can be substantially flush with an outer surface of the main body. This means that the outer surfaces merge into each other in a virtually seamless manner. This allows for efficient use of the installation space. Furthermore, it ensures axial contact between the ring component and the main body, thus forming an axial stop.

[0023] According to a preferred embodiment, the ring component can form a (first) sealing surface for the first sealing ring, in particular a radial shaft seal, on its outer circumferential surface. This means that the (first) sealing surface is not formed on the (cast) main body, so that the main body neither has to meet the requirements for a sealing surface nor comes into contact with the environment separated by the sealing ring. This has the advantage that the main body can be optimized for torque transmission.

[0024] According to a preferred embodiment, the ring component can form a (second) sealing surface for a second sealing ring, in particular an O-ring, on its inner circumferential surface. This means that the (second) sealing surface is not formed on the (cast) main body, so that the main body neither has to meet the requirements for a sealing surface nor comes into contact with the environment separated by the sealing ring. This has the advantage that the main body can be optimized for torque transmission.

[0025] According to a preferred embodiment, the ring component can be designed as a flow-formed part. This allows the ring component to be manufactured particularly cost-effectively.

[0026] The object of the invention is also achieved by a planetary gear system. The planetary gear system comprises a gear housing, a central sun gear rotatably mounted in the gear housing (i.e., coaxial to the axis of rotation / longitudinal axis of the planet carrier / planetary gear system), a planet carrier rotatably mounted in the gear housing, a ring gear fixedly connected to the gear housing and arranged coaxially to the sun gear, several planet gears mounted on the planet carrier and meshing with the sun gear and the ring gear, and a central output element (i.e., coaxial to the axis of rotation / longitudinal axis of the planet carrier / planetary gear system) connected to the planet carrier in a torque-transmitting manner.

[0027] According to a preferred embodiment, the ring component can have contact with an environment outside the gearbox housing. According to another preferred embodiment, the main body can have no contact with the environment outside the gearbox housing. This means that only the ring component (and not the main body) has contact with the environment when installed. In this way, the ring component can be optimized for contact with the environment, and the main body can be designed independently.

[0028] According to a preferred embodiment, the planetary gear can have a radial shaft seal arranged between the gear housing and the ring component, in particular on the (first) sealing surface. This ensures the tightness of the gear housing.

[0029] According to a preferred embodiment, the planetary gear can have a sealing ring (O-ring) arranged between the ring component and the output element, in particular on the (second) sealing running surface. This ensures the tightness of the gear housing.

[0030] According to a preferred embodiment, the planetary gear can have a bearing that supports the main body on the sun gear, in particular arranged on the (first) bearing raceway, and in particular designed as a 4-point bearing / axial bearing. This ensures the support of the planet carrier.

[0031] According to a preferred embodiment, the planetary gear can have a bearing that supports the main body in the gear housing, in particular arranged on the (second) bearing raceway, and in particular designed as an angular contact ball bearing. This ensures the support of the planet carrier.

[0032] In other words, the invention relates to a planetary carrier made entirely of cast iron. This means that the splined connection is also made of cast iron. Only the raceway for the radial shaft ring is designed as a pressed-on metal ring. In the installed state, only the metal ring has contact with the environment, not the planetary carrier or the cast iron part of the planetary carrier. The complex insertion geometry is completely integrated within the metal ring, and only the metal ring makes contact with the O-ring in the installed state. This allows the planetary carrier, or the cast iron part of the planetary carrier, to be optimized for torque transmission, for example, through material selection and / or heat treatment, and the metal ring can be optimized for the raceway and environmental conditions, for example, through coating or heat treatment.

[0033] Advantageously, the metal ring can be manufactured particularly cost-effectively, for example, as a flow-formed part. The one-piece planet carrier, or the one-piece design with the cast iron portion of the planet carrier (previously formed by a separate steel insert), eliminates the need for a second splined connection (between the steel insert and the cast planet carrier), thus allowing for greater design flexibility. Furthermore, the metal ring can easily be manufactured without twisting.

[0034] The invention is explained below with the aid of a drawing. It shows: Fig. 1 a longitudinal section view of a planet carrier according to the invention.

[0035] The figure is purely schematic and serves solely to illustrate the invention. The same elements are labelled with the same reference symbols.

[0036] Fig.Figure 1 shows a planet carrier 1 for a planetary gear 2. The planet carrier 1 serves to transmit torque from planet gears 3 mounted on the planet carrier 1. The planetary gear 2 is designed in particular for use in a (preferably electrically operated) motor vehicle drivetrain.

[0037] The planet carrier 1 has a bearing section 4 for supporting the planet gears 3, a toothed section 5 for transmitting a torque introduced into the planet carrier 1 by the planet gears 3, and a sealing section 6 for receiving a (radial shaft) sealing ring 7.

[0038] According to the invention, the planet carrier 1 has a main body 8 made of a single piece of material, which forms the bearing section 4 and the toothed section 5, and a ring component 9 formed separately from the main body 8 and placed on the main body 8 (firmly connected to the main body 8), which forms the sealing section 6.

[0039] In particular, the main body 8 can be designed as a cast component. This means that both the bearing section 4 and the gear section 5 are cast (in one piece). The ring component 9 can, in particular, be designed as a metal ring.

[0040] The main body has two parallel spaced-apart disks 10, which form the bearing section 4 and between which the planet gears 3 can be rotatably received, as well as a substantially tubular (end) section / hollow body section 11 extending from one of the disks 10 along an axis of rotation / longitudinal axis of the planet carrier / planetary gear, on the inner circumference of which the toothed section 5 is formed.

[0041] Preferably, the tubular section 11 can be internally stepped. In particular, the tubular section 11 can have a larger inner diameter in a first inner tube section 12 than in a second inner tube section 13, wherein the first inner tube section 12 is arranged closer to the bearing section 4 than the second inner tube section 13. This means that the inner diameter of the tubular section 11 tapers in a stepped manner in a direction away from the bearing section.

[0042] In particular, the main body 8 can form a first bearing raceway 14 on its inner circumferential surface for supporting the planet carrier 1. Preferably, the first bearing raceway 14 can be formed on the tubular section 11, particularly in the region of the first inner tube section 12. A transition between the first inner tube section 12 and the second inner tube section 13 can be designed as a step, which simultaneously serves as an axial stop surface for supporting the planet carrier 1.

[0043] Preferably, the tubular section 11 can be stepped on its outer surface. In particular, the tubular section 11 can have a larger outer diameter in a first outer tube section 15 than in a second outer tube section 16, wherein the first outer tube section 15 is arranged closer to the bearing section 4 than the second outer tube section 16. This means that the outer diameter of the tubular section 11 tapers in a stepped manner in a direction away from the bearing section 4.

[0044] In particular, the main body 8 can form a second bearing raceway 17 on its outer circumferential surface for supporting the planet carrier 1. Preferably, the second bearing raceway 17 can be formed on the tubular section 11, particularly in the region of the first outer tube section 15.

[0045] Preferably the bearing running surfaces 14, 17 are arranged essentially at the same height along the axis of rotation / longitudinal axis.

[0046] In particular, the main body 8 can form a receiving surface 18 on its outer circumferential surface for receiving the ring component 9. Preferably, the receiving surface can be formed on the tubular section 11, particularly in the area of ​​the second outer tube section 16.

[0047] Preferably, the tubular section 11 in the area of ​​the first outer tube section 15 can have a significantly larger wall thickness, for example at least twice as large, but at most 10 times as large, as in the area of ​​the second outer tube section 16.

[0048] In particular, the ring component 9 can have an annular cross-section. Preferably, the annular cross-section is substantially constant over the entire axial / longitudinal extent of the ring component 9. This means that the ring component 9 preferably has no steps on the outer and inner circumferences or any significant changes in cross-section. The wall thickness of the ring component 9 corresponds substantially to the wall thickness of the second outer tube section 16, i.e., approximately 0.5 to 2 times the wall thickness of the second outer tube section 16.

[0049] The ring component is preferably placed onto the receiving surface 18 of the main body 8. In particular, the ring component 9 can be pressed onto the main body 8, especially onto the tubular section 11, particularly in the area of ​​the second outer tube section 16.

[0050] Preferably, an outer surface of the ring component 8 can be substantially flush with an outer surface of the main body 11. That is, the outer surfaces merge into each other in a substantially planar manner. A step can be formed in the second outer tube section 16, which serves as an axial stop surface for the ring component 8.

[0051] In particular, the ring component 8 can form a first sealing running surface 19 on its outer circumferential surface for the first sealing ring 7, in particular a radial shaft seal ring.

[0052] In particular, the ring component 8 can form a second sealing running surface 20 on its inner circumferential surface for a second sealing ring 21, in particular an O-ring.

[0053] Preferably, the ring component can be designed as a flow-formed part.

[0054] The planet carrier 1 is part of the planetary gear set 2. The planetary gear set 2 has a gear housing 22. Furthermore, the planetary gear set 2 has a central sun gear 23 (sun shaft) rotatably mounted in the gear housing 22 (i.e., coaxial with the axis of rotation / longitudinal axis of the planet carrier 1 / planetary gear set 2). As described, the planetary gear set 2 has the planet carrier 1 rotatably mounted in the gear housing 22. In addition, the planetary gear set has a ring gear 24 fixedly connected to the gear housing 22 and arranged coaxially with the sun gear 23. Furthermore, the planetary gear set 2 has several planet gears 3 mounted on the planet carrier 1 and meshing with the sun gear 23 and the ring gear 24. Furthermore, the planetary gear 2 has a central output element 25 (i.e. coaxial with the axis of rotation / longitudinal axis of the planetary carrier 1 / planetary gear 2) which is connected to the planetary carrier 1 in a torque-transmitting manner.

[0055] In particular, the ring component 9 can have contact with an environment outside the gearbox housing 22 and the main body 8 can have no contact with the environment outside the gearbox housing 22.

[0056] Preferably the planetary gear 2 can have a (radial shaft) sealing ring 7 arranged between the gear housing 22 and the ring component 9, in particular arranged on the first sealing running surface 19.

[0057] Preferably the planetary gear 2 can have a sealing ring 21 (O-ring) arranged between the ring component 9 and the output element 25, in particular arranged on the second sealing running surface 20.

[0058] In particular, the planetary gear 2 can have a bearing 26 which supports the main body 9 on the sun gear 23, in particular arranged on the first bearing running surface 14, and in particular designed as a 4-point bearing / axial bearing.

[0059] Furthermore, the planetary gear can have a bearing 27 which supports the main body 9 in the gear housing 22, in particular arranged on the (second) bearing running surface 17, and in particular designed as an angular contact ball bearing.

[0060] The planet gears 3 are each rotatably mounted on a bearing 28, in particular a radial needle bearing, on a bolt 29, the bolt 29 being connected to the disks 10. An oil collection tray 30 collects the oil from the bolts 29.

[0061] The sun gear 23 has an interface 31 to a drive, in particular an electric motor. A further radial shaft seal 32 is arranged between the sun gear 23 and the gearbox housing 22.

[0062] The planet carrier 1 is mounted on the gearbox housing 22 via a bearing 33, which is designed in particular as an axial needle bearing.

[0063] The gearbox housing 22 is in contact with a grounding ring 34. Reference symbol list 1 Planetary Carrier 2 planetary gears 3 planetary gear 4 Storage section 5 Gear section 6 Sealing section 7 Sealing ring 8 Main body 9 Ring component 10 slices 11 tubular section 12 first inner pipe section 13 second inner pipe section 14 first bearing surface 15 first outer pipe section 16 second outer pipe section 17 second bearing surface 18 recording area 19 first sealing surface 20 second sealing surface 21 Sealing ring 22 Gearbox housings 23 Sun wheel 24 ring gear 25 Output element 26 warehouses 27 warehouses 28 warehouses 29 bolts 30 Oil drip tray 31 Interface 32 Radial shaft seal 33 warehouses 34 Grounding ring

Claims

[1] Planet carrier (1) for a planetary gear (2), for transmitting torque from planetary gears (3) mounted on the planet carrier (1), with a bearing section (4) for supporting the planetary gears (3), a toothed section (5) for transmitting a torque introduced into the planet carrier (1) by the planetary gears (3) and a sealing section (6) for receiving a sealing ring (7), characterized by that the planet carrier (1) has a one-piece main body (8) which forms the bearing section (4) and the toothed section (5), and a ring component (9) which is formed separately from the main body (8) and placed on the main body (8) and which forms the sealing section (6). [2] Planet carrier (1) according to claim 1, characterized by that the main body (8) is designed as a cast component. [3] Planet carrier (1) according to claim 1 or 2, characterized bythat the main body (8) forms a bearing surface (14) on its inner peripheral surface for supporting the planet carrier (1). [4] Planet carrier (1) according to one of claims 1 to 3, characterized by that the ring component (9) is designed as a metal ring. [5] Planet carrier (1) according to one of claims 1 to 4, characterized by that the main body (8) has a substantially tubular portion (11) on the inner circumference of which the toothed portion (5) is formed, and that the ring component (9) is pressed onto the tubular portion (11). [6] Planet carrier (1) according to one of claims 1 to 5, characterized by that the ring component (9) forms a running surface (19) for a first sealing ring (7) on its outer peripheral surface and / or forms a running surface (20) for a second sealing ring (21) on its inner peripheral surface. [7] Planet carrier (1) according to one of claims 1 to 6, characterized bythat the ring component (9) is designed as an extruded part. [8] Planetary gear (2) with a gear housing (22), a central sun gear (23) rotatably mounted in the gear housing (22), a planet carrier (1) rotatably mounted in the gear housing (22) according to one of claims 1 to 7, a ring gear (24) fixedly connected to the gear housing (22) and arranged coaxially to the sun gear (23), a plurality of planet gears (3) mounted on the planet carrier (1) and in toothed engagement with the sun gear (23) and the ring gear (24), and a central output element (25) connected to the planet carrier (1) in a torque-transmitting manner. [9] Planetary gear (2) according to claim 8, characterized by that the ring component (9) has contact with an environment outside the gear housing (22) and the main body (8) has no contact with the environment outside the gear housing (22). [10] Planetary gear (2) according to claim 8 or 9, characterized bythat the planetary gear (2) has a sealing ring (7) arranged between the gear housing (22) and the annular component (9) and / or a sealing ring (21) arranged between the annular component (9) and the output element (25) and / or a bearing (26) supporting the main body (9) on the sun gear (23).

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