Axial fixation of planet gear bolts in a planet carrier

Abstract

The invention relates to a planet carrier (5) of a planetary gear (1) comprising different planet sets integrated in a planet carrier (5) which is composed of at least two parts, wherein each planet set comprises a plurality of planet bolts (2) distributed peripherally, located in the planet carrier (5) and having a central bore (16), the planet bolts (2) being inserted in bores (13, 15) of opposite wall sections of the planet carrier (5) and at least one planet gear (9, 10) being rotatably supported on each planet bolt (2), the bores (13, 15) in the planet carrier (5) web (12) and in the differential cover (7) being designed accordingly before the planet bolts (2) are installed, so that the planet bolts (22) are permanently axially fixed after installation without any finishing work.

Description

Technical Field

[0001] The present invention relates to a planetary gear carrier of a planetary gear transmission device, comprising different planetary gear sets integrated in a planetary gear carrier consisting of at least two parts, wherein each planetary gear set includes a plurality of peripherally distributed planetary gear bolts located in the planetary gear carrier and having a central hole, the planetary gear bolts being inserted into holes in opposite wall sections of the planetary gear carrier, and at least one planetary gear being rotatably supported on each planetary gear bolt. Background Technology

[0002] Planetary gear transmissions are particularly used in the transmissions of motor vehicles. Due to their compact structure, they achieve higher power density compared to other transmission configurations, high torque transmission with minimal structural space, and the ability to change the gear ratio under load without interrupting power. The simplest form of a planetary gear transmission, the so-called single-stage planetary gear transmission, generally consists of a sun gear, multiple planet gears, a planet carrier, and an internal ring gear. The sun gear is rigidly connected to the internally meshing internal ring gear through each planet gear used. In principle, the sun gear, planet carrier, or internal ring gear can all be driven, either directly or indirectly. Depending on the required gear ratio or reduction ratio, a planetary gear transmission may include one or more planetary gear sets, also known as planetary gear stages.

[0003] DE 10 2017 112 341 A1 describes a planetary gear transmission device comprising multiple planetary gear sets. The device has a planetary gear carrier with multiple planetary gear bolts, on which planetary gears of different planetary gear sets are arranged. The planetary gear carrier has three axially spaced, disc-shaped metal plate components forming bracket cheeks, two outer walls, and one partition wall, which axially define the mounting space for each planetary gear set. The wall regions, outer walls, and partition wall are fixedly connected to each other by force transmission and / or rigid anchoring of the planetary gear bolts. The planetary gear bolts can be fastened by press fit, bolted connection, or material fit connection, such as welding.

[0004] A planetary gear transmission device, referred to as a gearbox, is known from EP 2 821 672 A1. This planetary gear transmission device is used in an electric drive unit and consists of a cylindrical gear differential and a reduction stage. The reduction stage is a planetary gear transmission mechanism whose sun gear is distributed to the motor rotor shaft. In the cylindrical gear differential, the planetary gears constitute the differential gears, while the sun gear distributed to the output shaft constitutes the driven gear. The torque transmitted via the input shaft or rotor shaft is transmitted through the reduction stage to the cylindrical gear differential, then distributed to the output shaft, and subsequently to the driven wheels.

[0005] DE 10 2016 214 015 A1 discloses a planetary gear transmission designed as a cylindrical gear differential, comprising a plurality of planetary gears arranged peripherally in a planetary gear carrier. The planetary gears are rotatably mounted on their respective planetary gear bolts, for example via rolling bearings, which are inserted into mounting slots in the sidewalls or housing portion of the planetary gear carrier in a torsion-resistant manner. Summary of the Invention

[0006] The objective of this invention is to permanently and axially fix the planetary gear bolt in the planetary gear carrier. This permanent axial fixation requires no adjustment after installation, can be achieved simply and at low cost, and requires minimal assembly work.

[0007] This task is accomplished by a planetary gear carrier having the features of claim 1. Other preferred embodiments of the invention can be found in the dependent claims, drawings, and related descriptions.

[0008] According to the present invention, the purpose is to arrange the holes in the planetary gear carrier wall and the differential cover in such a way that the planetary gear bolts are permanently axially fixed after installation without any adjustments.

[0009] The concept of this invention is to prepare as many components or elements as possible for fixing planetary gear bolts so that no adjustments, such as seam closing or material deformation, are required after assembling or installing the planetary gear carrier.

[0010] According to this measure, all planetary gear carrier components that work in conjunction with the planetary gear bolt carrier are prepared so that the planetary gear bolts are axially tightened in the installed state with the required pretension, for example, as determined by simulation, and permanently fixed in position.

[0011] The solution provided by this invention advantageously ensures the axial fixation of the planetary gear bolt, which can withstand all loads, such as the interaction of adhesion friction, sliding friction, and / or torsion of the planetary gear carrier during the operation of the planetary gear transmission. Therefore, this invention constitutes an effective movement lock for the planetary gear bolt.

[0012] Currently known methods for axially securing planetary gear bolts often involve oscillating riveting, which requires relatively large geometric constraints. In contrast, the fixing method provided by this invention ensures permanent axial fixation of the planetary gear bolts even under smaller installation conditions.

[0013] The axial fixing of planetary gear bolts provided by this invention, which eliminates the need to loosen locking elements (such as rivets or screws), advantageously reduces the number of components and assembly work in planetary gear drives. Furthermore, regardless of the structural form, the solution provided by this invention can be advantageously installed in all planetary gear carriers, including modular planetary gear carriers, and can be transferred to all planetary gear drives, such as cylindrical gear differentials, symmetrical or asymmetrical differentials, reducers, or reduction stages. Moreover, the solution provided by this invention offers a cost advantage, as all measures required for axial fixing can be manufactured within a single-piece production range. After successful, preferably automated, assembly of the planetary gear carrier or planetary gear drive, no finishing work is required to axially fix the planetary gear bolts, which is particularly advantageous for planetary gear drives with a large number of components, employing modular planetary gear carriers.

[0014] According to a preferred embodiment of the invention that ensures improved axial fixation of the planetary gear bolt, it is axially fixed in the installed state to a shaped portion formed by local material plastic molding of at least two radially aligned holes via a first end face.

[0015] These molded parts ensure sufficient tightness even under high mechanical requirements (such as vibration) while the planetary gear drive is in operation.

[0016] A shaped section (also known as a perforation or slit) formed by partial plastic molding of the material effectively secures the planetary gear bolts in the differential cover. This measure effectively prevents axial movement and / or relative torsion, as well as tangential clearance, within the differential cover bore. Depending on the differential cover material or considering other boundary conditions, the shaped section can be a geometrically varied structure, such as triangular, rectangular, semi-circular, or elliptical.

[0017] To ensure further optimization of the axial fixation of the planetary gear bolts, multiple forming sections can be provided. A larger number of forming sections is particularly beneficial for planetary gear carriers subjected to large forces and / or deformations. Optimized axial fixation preferably includes four forming sections, for example, each staggered from the other by 90°.

[0018] The molded portions of the differential cover can be manufactured precisely and at a low cost using male molds. For this purpose, it is advantageous to use a mold whose number of male molds corresponds to the number of molded portions, so that the differential cover material for all molded portions can be plastically deformed simultaneously in a single production stage. Alternatively, the molded portions can be made, for example, by roll forming, magnetic pulse forming, or using female molds.

[0019] Furthermore, in the installed state, the planetary gear bolts are axially fixed in the planetary gear carrier interlayer hole, which serves as a blind hole, via the second end face. This fixation, along with the fixation on the differential cover molding, ensures the permanent axial positioning of the planetary gear bolts. This also improves the torsional stiffness of the planetary gear carrier. This torsional stiffness has a positive impact, for example, on planetary gear bearings that reduce gear meshing forces. Therefore, the axial fixation of the planetary gear bolts makes a significant contribution to achieving trouble-free operation of the entire planetary gear system.

[0020] Lubricant is supplied to the planetary gear bearing, which acts as a sliding bearing, by means of a planetary gear bolt axially fixed in the planetary gear carrier according to the invention. For this purpose, the lubricant, particularly oil, flowing into the central hole of the planetary gear bolt is delivered to the bearing via at least one radial hole in the planetary gear bolt. Since the planetary gear bolt is arranged in a blind hole in the partition wall, one side of the central hole of the planetary gear bolt is closed.

[0021] The planetary gear's bearings are sliding bearings, wherein at least one sliding surface of the sliding bearing has a manganese phosphate coating. As a measure to supply a greater flow of lubricant to the bearing, an oil pan is provided to the planetary gear bolt, through which the absorbed lubricant is specifically delivered to the central bore. For this purpose, the oil pan, preferably made of sheet metal and formed without machining, is preferably pressed into the central bore via a tubular flange.

[0022] The axial fixing of the planetary gear bolts provided by this invention can be advantageously transferred to the planetary gear carrier, the various components of which are made of materially different or the same material. For example, in a planetary gear carrier whose components include a housing made by flow stamping or casting processes, the housing is combined with a differential cover made of sheet steel.

[0023] The planetary gear bolts, utilizing the axially fixed planetary gear transmission device provided by this invention, can be coupled to an electric motor for use in so-called electric vehicle axles in motor vehicles. Electric vehicle axles are a solution for electric drive or hybrid applications in battery electric vehicles. In electric vehicle axles, components that are conventionally used separately, such as the motor, axle, and transmission, are combined into a single structural unit. Attached Figure Description

[0024] The present invention will now be described in detail with reference to the two accompanying drawings showing two embodiments. However, the present invention is not limited to the two embodiments shown. Wherein:

[0025] Figure 1 A planetary gear transmission device having a first embodiment of the axially fixed planetary gear bolt provided by the present invention;

[0026] Figure 2A planetary gear transmission device having a second embodiment of the axially fixed planetary gear bolt provided by the present invention;

[0027] Explanation of reference numerals in the attached figures

[0028] 1. Planetary gear transmission 2. Planetary gear bolt 3. Cylindrical gear differential 4. Reduction stage 5. Planetary gear carrier 6. Housing 7. Differential cover 8. Receiving space 9. Planetary gear 10. Planetary gear 11. Bearing 12. Partition wall 13. Drilling hole 14. Molding part 15. Drilling hole 16. Center hole 17. Radial hole 21. Planetary gear transmission 22. Planetary gear bolt 23. Cylindrical gear differential 24. Reduction stage 25. Planetary gear carrier 26. Housing 27. Differential cover 28. Receiving space 29. Planetary gear 30. Planetary gear 31. Bearing 32. Partition wall 33. Drilling hole 34. Molding part 35. Drilling hole 36. Center hole 37. Radial hole 38. Oil pan 39. Opening 40. Flange 41. Rotation axis Detailed Implementation

[0029] The following description of the accompanying drawings is provided to better understand the present invention. Identical components are referred to by the same reference numerals.

[0030] Figure 1 This is a planetary gear transmission device 1 having a first preferred embodiment of the axially fixed planetary gear bolt 2 provided by the present invention; the planetary gear transmission device 1 includes different planetary gear sets, which are assigned to a cylindrical gear differential 3 and a reduction stage 4 jointly integrated in a planetary gear carrier 5. For this purpose, a housing 6 is provided for the reduction stage 4, and a receiving space 8 axially defined by the housing 6 and a differential cover 7 is provided for the cylindrical gear differential 3. The multi-piece planetary gear carrier 5 includes a cast housing 6 and a differential cover 7 made of sheet steel, preferably stamped. The cylindrical gear differential 3 and the reduction stage 4 include a plurality of planetary gears 9, 10 distributed and positioned along the tangential direction of the planetary gear carrier 5, which mesh with a central sun gear (not shown) on the inner side and with an internal gear ring (not shown) on the outer side, respectively.

[0031] Planetary gears 9 and 10, assigned to separate planetary gear sets, differ in their mounting positions and widths or axial extensions. Planetary gear 9 of the cylindrical gear differential 3 is rotatably positioned on planetary gear bolt 2 via bearing 11, which acts as a sliding bearing. This planetary gear bolt is inserted into hole 15 in the partition wall 12 (a blind hole) and hole 13 in the differential cover 7. The axially fixed mounting position of planetary gear bolt 2 is ensured by a molded portion 14 of the differential cover 7, which is formed radially into hole 13 by means of a targeted material and simultaneously end-face supported on planetary gear bolt 2 in a force-transmitting manner.

[0032] The holes 15 in the partition wall 12 and the molded portion 14 of the differential cover 7 are manufactured in single-piece production and therefore made before the planetary gear carrier 4 is assembled.

[0033] In order to supply lubricant to the bearing 11 of the planetary gear 9, when the planetary gear transmission 1 is in operation, the lubricant, such as oil, reaches the center hole 16 of the planetary gear bolt 2 and is then delivered directly to the bearing 11 from there via the radial hole 17. Because the hole 15 in the partition wall 12 serves as a blind hole or pocket hole, the end of the center hole 16 is closed when the planetary gear bolt 2 is installed.

[0034] Figure 2 In another embodiment of the axially fixed planetary gear bolt 22, wherein... Figure 2 In, with Figure 1 All corresponding parts are marked with an increase of 20 in the reference numerals. The following description is limited to the parts with respect to the reference numerals. Figure 1 Different components and parts.

[0035] according to Figure 2 The planetary gear bolt 22 is arranged in the planetary gear carrier 25 of the planetary gear transmission 21 and is axially fixed by means of the formed portion 34 of the differential cover 27. To supply a larger flow rate of lubricant to the bearing 31, an oil pan 38 is provided for the planetary gear bolt 22. The oil pan 38, preferably made of sheet metal, is inserted into a central bore 36 through a tubular flange 40, wherein the opening 39 is radially aligned with the axis of rotation 41 of the planetary gear transmission 21. In operation, the injected lubricating oil is received through the oil pan 38, conveyed to the central bore 36 by centrifugal force, and from there delivered to the bearing 31 via the radial holes 37 of the planetary gear bolt 22.

Claims

1. A planet carrier of a planetary gear (1, 21) comprising different planet sets which are integrated in a planet carrier (5, 25) which is composed of at least two parts, wherein Each planetary gear set comprises a plurality of peripherally distributed, centrally bored planet gear bolts (2, 22) in the planet carrier (5, 25), which are inserted in the holes (13, 15; 33, 35) of the opposite wall sections of the planet carrier (5, 25) and on each planet gear bolt (2, 22) at least one planet gear (9, 10; 29, 30) is rotatably supported, characterized in that the holes (13, 15; 33, 35) in the planet carrier (5, 25) web (12, 32) and the differential cover (7, 27) are designed accordingly before the planet gear bolts (2, 22) are installed, so that the planet gear bolts (2, 22) are permanently axially fixed after installation without any finishing work.

2. The planetary carrier of claim 1, wherein, In the installed state the planet gear bolts (2, 22) are axially fixed by the first end face on the shaped section (14, 34) of at least two radially aligned holes (13, 33), which is generated by local plastic material deformation of the differential cover (7, 27).

3. The planetary carrier of claim 2, wherein, For generating the shaped section (14, 34) of the differential cover (7, 27) a male or female mold is used.

4. The planetary carrier of claim 1, wherein, In the installed state the planet gear bolts (2, 22) are axially fixed by the second end face in the holes (15, 35) of the planet carrier (5, 25) web (12, 32), which are designed as blind holes.

5. The planet carrier according to any one of the preceding claims, characterized in that The planet gear bolts (2, 22) contain at least one radial hole (17, 37) connecting the central bore (16, 36) with the bearing (11, 31) for supplying the bearing (11, 31) of the planet gear (9, 29) with lubricant.

6. The planetary carrier of claim 5, wherein, The bearing (11, 31) is a plain bearing, wherein at least one sliding surface of the plain bearing has a manganese phosphate coating.

7. The planetary carrier of claim 5, wherein, The lubricant is supplied to the planet gear bolt (22) through the central bore (36) by an oil sump (38).

8. The planetary carrier of claim 7, wherein, The oil sump (38) which is formed without cutting from sheet metal is pressed into the central bore (36) by a tubular flange (40).

9. The planet carrier according to any of the preceding claims 1 - 4, 6 - 8, characterized in that, The housing (6, 26) of the planet carrier (5, 25) and the differential cover (7, 27) are made of different or the same material.

10. The planet carrier according to any of the preceding claims 1 - 4, 6 - 8, characterized in that, The planetary gear (1, 21) is coupled with an electric motor for an electrically driven axle of a motor vehicle.

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