Axial fixing of planetary gear bolts in a planet carrier

Abstract

Planet carrier of a planetary gear set (1, 21) which includes different planet sets integrated in a planet carrier (5, 25) of at least two parts, wherein each planet set comprises several planet gear bolts (2, 22) positioned circumferentially in the planet carrier (5, 25) and having a central bore (16, 36), which are inserted into bores (13, 15; 33, 35) of opposite wall sections of the planet carrier (5, 25) and on which at least one planet gear (9, 10; 29, 30) is rotatably mounted on each planet gear bolt (2, 22), wherein prior to assembly of the planet gear bolt (2, 22) the bores (13, 15; 33, 35) in an intermediate wall (12, 32) and in a differential cover (7, 27) of the planet carrier (5, 25) are designed such that that the planet gear bolt (2, 22) is permanently axially fixed after assembly without any rework, characterized in that - the planet gear bolt (2, 22) is axially fixed in the installed state with a first end face to at least two formed sections (14, 34) produced by means of a local plastic deformation of the differential cover (7, 27) which are radially aligned into the bore (13, 33) and - the planet gear bolt (2, 22) is axially fixed in the installed state with a second end face in a bore (15, 35) designed as a blind bore in the intermediate wall (12, 32) of the planet carrier (5, 35) and - lubricant flows into the central bore (36) of the planet gear bolt (22) via an oil collection tray (38).

Description

[0001] The invention relates to a planet carrier of a planetary gear unit, which includes different sets of planets integrated in a planet carrier constructed of at least two parts, wherein each set of planets comprises several planet gear bolts positioned circumferentially in the planet carrier, having a central bore, which are inserted into bores in opposing wall sections of the planet carrier and at least one planet gear is rotatably mounted on each planet gear bolt.

[0002] Planetary gear sets are used particularly in the transmissions of motor vehicles. Due to their compact design, they offer a high power density compared to other gear types, high torque transmission in a very small installation space, and the ability to change the gear ratio under load without interrupting the power flow. The simplest form of a planetary gear set, a so-called single-stage planetary gear set, basically consists of a sun gear, a number of planet gears, a planet carrier, and a ring gear. The sun gear is positively connected to the internally toothed ring gear via each of the planet gears. In principle, either the sun gear, the planet carrier, or the ring gear can be driving, driven, or fixed. Depending on the required gear ratio, the planetary gear set can include one or more sets of planet gears, also called planetary stages.

[0003] German patent application DE 10 2017 112 341 A1 discloses a planetary gear unit comprising multiple planetary gear sets. The planetary gear unit features a planet carrier with several planet gear pins on which the planet gears of the different planetary gear sets are mounted. The planet carrier has three axially spaced, disc-like sheet metal components forming support sides: two outer walls and an intermediate wall, which axially define the installation spaces for the individual planetary gear sets. The wall sections, the outer walls, and the intermediate wall are firmly connected to one another by force-fit and / or form-fit anchoring of the planet gear pins. The planet gear pins can be fastened by an interference fit, a bolted connection, or a material-bonded connection such as welding.

[0004] From EP 2 821 672 A1, a planetary gear set, described as a transmission device, is known, intended for an electric drive unit and consisting of a spur gear differential and a reduction stage. The reduction stage is a planetary drive whose sun gear is assigned to a rotor shaft of the electric motor. In the spur gear differential, the planet gears form the differential gears and the sun gears assigned to an output shaft form the output gears. The torques applied via the input shaft or rotor shaft are introduced into the spur gear differential via the reduction stage and then distributed to the output shaft and thus to the driven vehicle wheels.

[0005] DE 10 2016 214 015 A1 discloses a planetary gear set designed as a spur gear differential, which includes several planet gears arranged circumferentially in a planet carrier. The planet gears are rotatably mounted, for example via rolling bearings, on associated planet gear bolts, which are rotationally fixed in receptacles in side walls or housing sections of the planet carrier.

[0006] DE 10 2012 208 799 A1 discloses a planetary gear unit with at least one sun gear and at least one planet carrier arranged coaxially and rotatably to this, wherein a bearing sleeve is inserted between the at least one sun gear and the planet carrier in such a way that it acts axially and / or radially on the sun gear relative to the planet carrier.

[0007] EP 2 821 672 A1 shows a planetary gear bolt, one end of which is inserted into a blind hole.

[0008] DE 10 2016 222 444 A1 discloses an assembly for a drive with at least one planet carrier, with a first planet set, wherein the first planet set comprises a plurality of first planet gears, wherein the first planet gears are rotatably arranged on the planet carrier in a first pitch circle diameter, with an oil collection tray for collecting and conveying oil, wherein the oil collection tray is arranged on the planet carrier, wherein a second planet set, wherein the second planet set comprises a plurality of second planet gears, wherein the second planet gears are rotatably arranged on the planet carrier in a second pitch circle diameter, the oil collection tray comprising at least first elements for conveying the oil to the first planet gears and second elements for conveying the oil to the second planet gears.

[0009] DE 10 2011 087 570 A1 discloses a generator differential combination for a motor vehicle, comprising a generator having a rotor which interacts electromagnetically with a stator, and a differential comprising two sun gears between which torque can be transmitted via at least one connecting gear and the connecting gear is mounted in a support component such that the torque can be transmitted from the rotor to at least one sun gear and the differential is designed as a spur gear differential.

[0010] DE 10 2015 214 035 A1 discloses an electronic drive unit for a motor vehicle, comprising an electric motor and an associated transmission arrangement, wherein the transmission arrangement has a transmission input stage and a differential connected to it via a common planet carrier, wherein the differential has a first and a second planet set, wherein the first planet set combs with a first sun and the second planet set with a second sun, and wherein the two planet sets of the differential comb with each other in pairs.

[0011] The object of the invention is to create a durable axial fixation for planetary gear bolts in planet carriers, which requires no rework after the planetary gear bolt has been installed and which can be implemented simply and cost-effectively with little assembly effort.

[0012] This problem is solved by a planet carrier with the features of claim 1. Further preferred embodiments of the invention can be found in the dependent claims, the figures, and the accompanying description.

[0013] According to the invention, it is provided that, prior to mounting the planet gear bolt, the bores in an intermediate wall and in a differential cover of the planet carrier are designed in such a way that the planet gear bolt is permanently axially fixed after mounting without any rework.

[0014] The concept of the invention provides for preparing the components or the elements intended to receive the planetary gear bolt to such an extent that no rework such as riveting or material deformation is required after assembly or mounting of the planetary gear carrier.

[0015] According to this measure, all components of the planet carrier that interact with the planet gear bolt are prepared so that the planet gear bolt is axially pre-tensioned and permanently fixed in position with the required pre-tension, determined for example by a simulation, when installed.

[0016] Advantageously, the concept according to the invention ensures axial fixation of the planet gear bolt, which withstands all occurring loads such as interactions of static and sliding friction and / or twisting of the planet gear carrier during the operating state of the planetary gear. Thus, the invention provides an effective anti-movement device for the planet gear bolt.

[0017] Previously known axial fixings of planetary gear bolts were often achieved using orbital riveting, which requires relatively large geometric dimensions. In comparison, the fixing method according to the invention ensures a durable axial fixing of the planetary gear bolt even in smaller installation conditions.

[0018] The inventive axial securing of the planetary gear bolt, which does not require any loose securing elements such as rivets or screws, advantageously reduces the number of components and the assembly effort of the planetary gear. Furthermore, the inventive concept is advantageously applicable to all planetary carriers, including combined planetary carriers, regardless of their design, and can be transferred to all planetary gears, such as spur gear differentials, symmetrical or asymmetrical differentials, reduction gears, or reduction stages. In addition, the application of the inventive concept offers a cost advantage, since all measures required for axial fixation can be manufactured during the individual component production process. After the planetary carrier has been assembled, preferably automatically, the...No rework is required for the axial fixing of the planet gear bolts in the planetary gear, which is particularly advantageous for planetary gears with combined planet carriers that are manufactured in large quantities.

[0019] According to the invention, to ensure improved axial fixation of the planet gear bolt, it is axially secured in the installed state with a first end face to at least two formed sections radially aligned into the bore, produced by means of a local plastic material deformation of the differential cover.

[0020] These forming sections ensure reliable protection even under high mechanical demands, such as vibrations, during the operating state of the planetary gearbox.

[0021] The forming sections, also known as through-holes or rivets, produced by partial plastic deformation of the material, effectively anchor the planet gear bolt in the differential cover. This measure effectively prevents axial movement and / or relative rotation, as well as tangential play in the differential cover bore. Depending on the material of the differential cover or other boundary conditions, the forming sections can be designed in geometrically different shapes, for example, triangular, rectangular, semicircular, or oval.

[0022] To ensure further optimized axial fixation of the planet gear bolt, it is advantageous to provide several forming sections. A larger number of forming sections is particularly beneficial for planet carriers that are subjected to greater forces and / or deformations. Preferably, an optimized axial fixation includes four forming sections, which are positioned, for example, offset from each other by 90°.

[0023] The forming sections of the differential cover can be manufactured precisely and cost-effectively using a punch. A tool whose number of punches advantageously corresponds to the number of forming sections is suitable for this purpose, allowing the material of the differential cover to be plastically deformed simultaneously for all forming sections in a single manufacturing step. Alternatively, the forming sections can be produced, for example, by rolling, magnetic pulse forming, or using a die.

[0024] In its installed state, the planet gear bolt is also axially fixed, according to the invention, by a second end face in a blind bore in an intermediate wall of the planet carrier. This fixation, together with the fixation to the formed sections of the differential cover, ensures a durable axial positional retention of the planet gear bolt. Furthermore, this improves the torsional stiffness of the planet carrier, which, for example, positively influences the bearing of the planet gears and reduces the gear meshing forces. Consequently, the axial fixation of the planet gear bolt is an important component for ensuring the trouble-free operation of the entire planetary gear set.

[0025] Lubrication of the planet gear bearing, which is designed as a sliding bearing, is simultaneously achieved via the planet gear bolt, which is axially fixed in the planet carrier according to the invention. For this purpose, the lubricant, in particular oil, flowing into the central bore of the planet gear bolt, is supplied to the bearing via at least one radial bore of the planet gear bolt. Due to the arrangement of the planet gear bolt in a blind bore of the intermediate wall, the central bore of the planet gear bolt is closed on one side.

[0026] The planet gears are mounted as plain bearings, with at least one of the sliding surfaces having a manganese phosphate coating. To increase the lubricant flow to the bearing, an oil collection tray is provided for the planet gear pin, directing the collected lubricant into the central bore. This oil collection tray, preferably formed from sheet metal without machining, is preferably pressed into the central bore with a tubular extension.

[0027] The axial fixing of the planet gear bolt according to the invention is advantageously transferable to planet carriers whose individual components are made of different or identical materials. For example, to planet carriers whose individual parts comprise a housing produced by extrusion or a casting process, which is combined with a differential cover stamped from a sheet of steel.

[0028] The planetary gear, whose planetary gear pin is axially secured by the measures according to the invention, can be coupled with an electric motor for use in a so-called e-axle of a motor vehicle. The e-axle is a solution for the electric drive of battery-electric vehicles or for hybrid applications. In the e-axle, components such as the motor, axle, and gearbox, which are used separately in conventional designs, are combined into a single unit.

[0029] The invention is described in more detail below with reference to two figures showing two exemplary embodiments. However, the invention is not limited to the two illustrated embodiments. The figures show: Fig. 1: a planetary gear with a first embodiment of a planet gear bolt axially secured according to the invention without the illustration of the oil collection tray according to the invention; Fig. 2: a planetary gear with a second embodiment of a planet gear bolt axially secured according to the invention, showing the oil collection tray according to the invention.

[0030] The following description of the figures of an exemplary embodiment is intended to facilitate a better understanding of the invention. Identical components are identified by corresponding reference numerals.

[0031] The Fig. Figure 1 shows a planetary gear set 1 with a first preferred embodiment of a planet gear pin 2 axially fixed according to the invention. The planetary gear set 1 includes different planet sets assigned to a spur gear differential 3 and a reduction stage 4, which are jointly integrated in a planet carrier 5. A housing 6 is provided for the reduction stage 4, and a receiving space 8, axially limited by the housing 6 and a differential cover 7, is provided for the spur gear differential 3. The multi-part planet carrier 4 comprises a housing 6 designed as a casting and a differential cover 7 made of sheet steel, preferably stamped. The spur gear differential 3, as well as the reduction stage 4, include several planet gears 9, 10 distributed around the circumference of the planet carrier 5, each of which is meshed internally with a central sun gear (not shown) and externally with a ring gear (not shown).

[0032] The planet gears 9 and 10, assigned to the separate planetary gear sets, differ from one another in their installation position and their width or axial extent. The planet gear 9 of the spur gear differential 3 is rotatably positioned on the planet gear pin 2 via a bearing 11 designed as a sliding bearing. The planet gear pin 2 is inserted into a bore 15 (designed as a blind bore) in an intermediate wall 12 and a bore 13 in the differential cover 7. Formed sections 14 of the differential cover 7 ensure an axially fixed installation position for the planet gear pin 2. These sections project radially into the bore 13 by means of targeted material deformation and are thereby positively supported at their end face by the planet gear pin 2.

[0033] The bore 15 in the partition wall 12 and the formed sections 14 of the differential cover 7 are manufactured as part of the individual part production and consequently before the assembly of the planetary gear carrier 4.

[0034] To supply the bearing 11 of the planet gear 9 with a lubricant, lubricant such as oil enters a central bore 16 of the planet gear bolt 2 during the operating state of the planetary gear 1 and from there via radial bores 17 directly to the bearing 11. Due to the bore 15 in the intermediate wall 12, which is designed as a blind bore or blind hole, the central bore 16 is closed at the end when the planet gear bolt 2 is inserted.

[0035] In the Fig. Figure 2 shows a further embodiment of an axially fixed planetary gear bolt 22, wherein in Fig. 2 all components that are connected to Fig. 1, with reference numbers increased by 20. The following description is largely limited to components and parts that differ from the Fig. 1. Differentiate.

[0036] According to Fig.2 The planet gear pin 22 is arranged in the planet carrier 25 of the planetary gear 21 and axially fixed in position by means of formed sections 34 of the differential cover 27. To supply the bearing 31 with a larger flow of lubricant, an oil collection tray 38 is associated with the planet gear pin 22. The oil collection tray 38, preferably formed from a sheet metal part, is inserted into the central bore 36 with a tubular extension 40, with an opening 39 oriented radially to a rotation axis 41 of the planetary gear 21. During operation, splash oil is collected via the oil collection tray 38, directed by centrifugal force into the central bore 36, and from there supplied to the bearing 31 via the radial bores 37 of the planet gear pin 22. Reference symbol list 1 planetary gear 2 planetary gear bolts 3 Spur gear differential 4 Reduction stage 5 planetary carriers 6 cases 7 Differential cover 8 Recording room 9 planetary gear 10 planetary gear 11 Storage 12 Partition wall 13 bore 14 Forming section 15 bore 16 Central bore 17 radial bore 21 planetary gears 22 planetary gear bolts 23 Spur gear differential 24 Reduction stage 25 planetary carriers 26 cases 27 Differential cover 28 Recording room 29 planetary gear 30 planetary gear 31 Storage 32 Partition wall 33 bore 34 Forming section 35 bore 36 Central bore 37 radial bore 38 Oil collection tray 39 Opening 40 Approach 41 axis of rotation

Claims

[1] Planet carrier of a planetary gear set (1, 21) which includes different planet sets integrated in a planet carrier (5, 25) of at least two parts, wherein each planet set comprises several planet gear bolts (2, 22) positioned circumferentially in the planet carrier (5, 25) and having a central bore (16, 36), which are inserted into bores (13, 15; 33, 35) of opposite wall sections of the planet carrier (5, 25) and on which at least one planet gear (9, 10; 29, 30) is rotatably mounted on each planet gear bolt (2, 22), wherein, prior to assembly of the planet gear bolt (2, 22), the bores (13, 15; 33, 35) in an intermediate wall (12, 32) and in a differential cover (7, 27) of the planet carrier (5, 25) are such that are designed so that the planet gear bolt (2, 22) is permanently axially fixed after assembly without any rework, characterized by , that - the planet gear bolt (2, 22) is axially fixed in the installed state with a first end face to at least two formed sections (14, 34) produced by means of a local plastic deformation of the differential cover (7, 27) which are radially aligned into the bore (13, 33) and - the planet gear bolt (2, 22) is axially fixed in the installed state with a second end face in a bore (15, 35) designed as a blind bore in the intermediate wall (12, 32) of the planet carrier (5, 35) and - lubricant flows into the central bore (36) of the planet gear bolt (22) via an oil collection tray (38). [2] Planetary carrier according to claim 1, characterized by , that a punch or die is used to produce the forming sections (14, 34) of the differential cover (7, 27). [3] Planetary carrier according to any one of the preceding claims, characterized by, that the planet gear bolt (2, 22) for the application of lubricant to a bearing (11, 31) of the planet gear (9, 29) includes at least one radial bore (17, 37) connecting the central bore (16, 36) with the bearing (11, 31). [4] Planetary carrier according to claim 3, characterized by , that the bearing (11, 31) is designed as a sliding bearing, wherein at least one of the sliding surfaces of the sliding bearing has a manganese phosphate coating. [5] Planetary carrier according to claim 1, characterized by , that the oil collection tray (38) formed without machining from a sheet metal material is pressed into the central bore (36) with a tubular extension (40). [6] Planetary carrier according to any one of the preceding claims, characterized by , that the individual components of the planet carrier (5, 25) such as the housing (6, 26) and the differential cover (7, 27) are made of different or identical materials. [7] Planetary carrier according to any one of the preceding claims, characterized by , that the planetary gear (1, 21) is coupled with an electric motor for an e-axle of a motor vehicle.

Images