Planetary gear with cover arrangement

Abstract

Planetary gear (1) with a planet carrier (3), wherein the planet carrier (3) has a first side disk section (10) and a sleeve section (11), wherein the first side disk section (10) and the sleeve section (11) form a receiving space (12) and wherein the planet carrier (3) defines a main axis of rotation (H), with a plurality of first planet gears (6), wherein the first planet gears (6) are arranged in a first axial region (4) of the planet carrier (3) in the receiving space (12), wherein the planet carrier (3) has first windows (15) in the sleeve section (11) in the first axial area (4), wherein the first windows (15) form passages for and / or to the first planet gears (6), wherein the planetary gear (1) has a cover arrangement (18) comprising a plurality of cover elements (19) for covering the first windows (15), characterized by the fact that the planet carrier (3) has a second window (16) as a blank window in a second axial area (5) in the sleeve section (11), and The lid elements (19) each cover a first and a second window (15, 16).

Description

[0001] The invention relates to a planetary gear unit with the features of the preamble of claim 1.

[0002] Planetary gear sets are known in a variety of designs, typically featuring a sun gear arranged coaxially to a main shaft that meshes with a plurality of planet gears. Depending on the application, the planetary gear set can also include two sun gears, several sets of planet gears, and / or a ring gear that meshes with the planet gears.

[0003] The publication DE 10 2010 024 597 A1, which probably represents the closest prior art, discloses a planetary gear with a protective cover, wherein the protective cover is placed on an axial side of the planetary gear.

[0004] DE 38 10 169 C2 describes a planetary gear unit whose planet carrier has a side disc section and a sleeve section with windows which are covered by a cover arrangement.

[0005] US 1 389 580 A also describes a planetary gear system whose planet carrier has a side disc section and a sleeve section with windows that are covered by cover elements.

[0006] DE 10 2015 214 035 A1 describes an electronic drive unit with a differential whose planet carrier has pockets arranged on several circumferential lines for receiving several sets of planets.

[0007] It is an object of the present invention to propose a planetary gear unit which exhibits improved operating characteristics. This object is achieved by a planetary gear unit with the features of claim 1. Preferred or advantageous embodiments of the invention will become apparent from the dependent claims, the following description, and the accompanying figures.

[0008] The invention relates to a planetary gear set, as is particularly preferably used in a vehicle, especially in a vehicle's drivetrain. In general, the planetary gear set serves to distribute, combine, increase, and / or reduce drive torque for the vehicle.

[0009] The planetary gear set is specifically designed as a spur gear planetary gear set, wherein the gears of the planetary gear set are particularly preferably designed as continuously toothed gear wheels and / or spur gears. The gears can have spur or helical teeth.

[0010] The planetary gear unit comprises a planet carrier, the planet carrier defining a main axis of rotation of the planetary gear unit with its axis of rotation. From a structural perspective, the planet carrier has a first side disk section and a sleeve section, which together form a receiving space. The first side disk section preferably extends in a radial plane to the main axis of rotation. The sleeve section is preferably arranged coaxially and / or concentrically to the main axis of rotation.

[0011] The first side disc section and the sleeve section form a common receiving space, the receiving space being limited in the axial direction by the first side disc section and in the radial direction by the sleeve section.

[0012] The planetary gear set comprises a plurality of first planet gears. Preferably, the axes of rotation of the first planet gears are arranged in a first pitch circle around the main axis of rotation. Axially, the first planet gears are positioned in a first axial region of the planet carrier. The first planet gears are arranged at least partially or completely within the receiving space.

[0013] Optionally, the planetary gear set includes a first sun gear, which meshes with the first planet gears. The first sun gear is arranged coaxially to the main axis of rotation.

[0014] The planet carrier has first windows which are incorporated into the sleeve section. The first windows can also be referred to as radial-circumferential windows. In particular, the first windows are incorporated into a wall of the sleeve section and preferably extend with a longitudinal edge in the direction of rotation around the main axis of rotation and / or with a transverse edge parallel to the main axis of rotation.

[0015] Such windows can be provided, for example, to reduce the weight of the planetary gear set, particularly the planet carrier. Furthermore, such windows can serve as recesses for additional components, especially the first planet gears.

[0016] Within the scope of the invention, it is proposed that the planetary gear unit has a cover arrangement for covering the first windows. In particular, the cover arrangement is designed such that the planet carrier, specifically the sleeve section in the first axial region, is closed at the outer circumference. The cover arrangement is particularly designed as a separate component or assembly from the sleeve section.

[0017] It is a consideration of the invention that such planetary gears, in particular such planet carriers, are typically used in a receiving chamber containing gear oil and / or in an oil atmosphere for lubrication. Thus, such planetary gears are arranged in a gear chamber in which the gear oil is also provided for lubricating the gears of the planetary gear and other components. When the planetary gear, in particular the planet carrier, rotates, it or sections thereof splash in the gear oil, which leads to increased resistance and thus to a reduced efficiency of the planetary gear. According to the invention, the cover arrangement covers the first windows and the second windows or openings, so that it acts as an oil baffle and reduces the resistance of the planetary gear, in particular the planet carrier.Preferably, the cover arrangement has a flow-optimized contour, so that the gear oil no longer flows against any disruptive contours of the planetary gear, in particular the planet carrier, but is guided around these contours. This improves the efficiency of the planetary gear and optimizes its operating behavior. Furthermore, the amount of gear oil that is flung out of the planetary gear due to centrifugal force is reduced, since the cover arrangement retains the gear oil.

[0018] According to the invention, the first windows form passages for and / or to the first planet gears. In particular, the first windows are arranged in the first axial region of the planet carrier, especially the sleeve section. Alternatively or additionally, the first windows are arranged in the direction of rotation around the main axis of rotation in the same position or at least in an overlapping position as the first planet gears. The first planet gears can be set back radially from the main axis of rotation relative to the sleeve section, so that the first planet gears and their teeth have a common outer circumference which is smaller than the free inner circumference of the sleeve section.In an alternative embodiment, the first planet gears, particularly their teeth, can extend into or even through the first windows, so that the common outer circumference of the teeth of the first planet gears is larger than the outer circumference of the sleeve section in the first axial area. In this embodiment, the diameter of the sleeve section, particularly its outer diameter, can be smaller than the common outer diameter of the first planet gears, allowing the sleeve section to be manufactured in a weight-optimized and / or space-optimized manner.

[0019] In a preferred embodiment of the invention, the cover assembly has hood sections for covering the first planet gears. Preferably, the cover assembly comprises base sections and hood sections, the base sections having a smaller outer diameter than the hood sections. The outer diameter of the base sections is particularly adapted to the outer diameter of the sleeve section, such that it is only slightly larger than the outer diameter of the sleeve section. This preferred embodiment is particularly useful when the first planet gears are almost flush with, or flush with, the outer diameter of the sleeve section in the radial direction relative to the main axis of rotation, or project beyond the outer diameter of the sleeve section. In particular, the first planet gears extend through the first windows and project beyond the outer circumference of the sleeve section.In this design, the entire interference contour of the planetary gear, particularly in the area of ​​the sleeve section, is only enlarged by the cover arrangement to the extent absolutely necessary. Thus, the interference contour is kept small.

[0020] In an optional configuration, the planetary gear set features a plurality of second planet gears arranged in the axial region of the first planet gears, i.e., in the first axial region. The first windows are designed as double windows, forming passages for and / or to the first and second planet gears. The cover assembly is designed to cover the first windows, which are configured as double windows. Preferably, the first planet gears and the second planet gears mesh with each other in pairs and / or are designed as compensating gears.

[0021] According to the invention, the planet carrier has second windows in the sleeve section, the second windows being arranged in a second axial region of the planet carrier. In particular, the second windows are axially offset from the first windows. In other words, the windows are arranged in at least or exactly two rows, with a first row being formed by the first windows and a second row by the second windows. According to the invention, the cover assembly additionally covers the second windows. According to the invention, the second windows are designed as empty windows and serve in particular to reduce weight.

[0022] In a possible further development of the invention, the planetary gear set comprises a plurality of third planet gears, wherein the third planet gears are preferably arranged in the second axial region of the planet carrier within the receiving space. Third windows are associated with the third planet gears, wherein the third windows are preferably arranged in a row with the second windows. According to the application, the third planet gears are designed to mesh with a ring gear, such that the third windows and / or the third planet gears are recessed by the cover assembly. These planet gears partially protrude from the windows.

[0023] According to the invention, the cover assembly comprises a plurality of cover elements. Preferably, the cover elements are each attached to the planet carrier independently of one another. This design has the advantage that the individual cover elements can be of a comparatively simple design and / or easier to assemble. Preferably, each individual cover element has at least or exactly one hood area and at least or exactly one base area.

[0024] In principle, the cover elements can be made of metal, especially sheet metal. For example, they are implemented as sheet metal components. However, it is preferred that the cover elements are made of plastic. In this configuration, they can be manufactured in freeform shapes, allowing them to be optimally adapted to the windows and / or the sleeve section.

[0025] According to the invention, each cover element covers a first and a second window. The first window can also be configured as a double window. For example, the cover elements are T-shaped in plan view, with the transverse leg covering the first window, in particular the double window, and the vertical leg covering the second window.

[0026] In a preferred embodiment of the invention, the first side disc section and the sleeve section are designed as a common, in particular one-piece, cup. In a possible further development, the planet carrier has a second side disc section, which is arranged opposite the first side disc section and forms a lid for the common cup. The lid elements can each have interfaces, in particular threaded sections, for attaching the lid elements to the side disc sections.

[0027] The cover arrangement incorporates an oil baffle and / or oil guide plate, which specifically covers the planet gears that project radially into or even beyond the sleeve section. The cover arrangement is designed to utilize a flow-optimized contour, ensuring that the transmission oil no longer flows against the planet gears but is instead guided around the planet carrier.

[0028] In a particularly preferred embodiment of the invention, the planetary gear set is designed as a differential device, wherein the first and second planet gears mesh with each other in pairs and form differential gears in the differential device. Furthermore, the first planet gears mesh with the first sun gear and the second planet gears mesh with a second sun gear.

[0029] In a preferred embodiment of the invention, the third planet gears form part of a reduction gear section. The third planet gears are driven via a ring gear. Optionally, the ring gear forms part of the planetary gear set.

[0030] Preferably, the planetary gear set is configured as a distribution gearbox for an electric motor in a vehicle with the planetary gear set as described above and / or according to one of the preceding claims. Preferably, the distribution gearbox and the electric motor form an electric axle for the vehicle. Preferably, a drive torque is introduced from the electric motor via the third planet gear set and distributed via the planet carrier and the first and second planet gear sets to the first and second sun gear sets, which form outputs to driven wheels of the vehicle. The advantages of the invention are particularly evident in the field of application of electrically powered vehicles, since these are characterized by higher rotational speeds of the components.

[0031] Further features, advantages, and effects of the invention will become apparent from the following description of a preferred embodiment of the invention and the accompanying figures. These show: Fig. 1 a schematic three-dimensional representation of a planetary gear as an embodiment of the invention; Fig. 2 the planetary gear from the Fig. 1 with attached lid elements; Fig. 3 a schematic, three-dimensional representation of a cover element for the planetary gear of the preceding figures; Fig. 4 in the same representation as in the Fig. 3 Another view of the lid element.

[0032] The Fig. Figure 1 shows a schematic, three-dimensional representation of a planetary gear 1, which is designed as a distribution gearbox for an electric motor 2 (only schematically indicated). The planetary gear 1 and the electric motor 2, optionally supplemented by an intermediate gearbox between the planetary gear 1 and the electric motor 2, form an electric axle in a vehicle.

[0033] The planetary gear set 1 has a planet carrier 3, which comprises a first axial section 4 and a second axial section 5. In the first axial section 4, first planet gears 6 and second planet gears 7 are rotatably mounted on the planet carrier 3. The first and second planet gears 6 and 7 mesh with each other in pairs. Furthermore, the first planet gears 6 mesh with a first sun gear, and the second planet gears 7 mesh with a second sun gear. The two sun gears each form an output from the planetary gear set 1 and transmit a drive torque to the driven wheels of the vehicle. In the second axial section 5, third planet gears 8 are rotatably mounted on the planet carrier 3. The third planet gears 8 mesh with a ring gear 9 (shown only schematically), which is driven directly or indirectly by the electric motor 2.

[0034] Functionally, a drive torque is introduced from the electric motor 2 via the ring gear 9 and the third planet gears 8 into the planetary gear set 1. This causes the planet carrier 3 to rotate. The rotation of the planet carrier 3 is transmitted to the sun gears. To compensate for angular velocities of the sun gears, they are coupled to each other differentially via the second and third planet gears 6, 7, with the second and third planet gears 6, 7 forming compensating gears within the differential.

[0035] From a structural perspective, the planet carrier 3 comprises a first side disc section 10 and a sleeve section 11, wherein the first side disc section 10 and the sleeve section 11 form a common receiving space 12. The common receiving space 12 can be subdivided by at least one or exactly one partition 13. The first side disc section 10 and the sleeve section 11 are formed in one piece and are made from a common semi-finished product. A second side disc section 14 is arranged on the opposite axial side of the sleeve section 11 and connected to the sleeve section 11, in this embodiment by screws. The two side disc sections 10 and 14 extend in a radial plane to a main axis of rotation H of the planetary gear 1. The sleeve section 11 has a straight cylindrical surface as its outer circumference, which is perforated in several areas.

[0036] The sleeve section 11 has four windows 15 in the first axial area, which are designed as double windows and are open towards the first and second planet gears 6, 7. In particular, the first planet gears 6 project into the first window 15, partially penetrate it, and can even project radially beyond the outer circumference and / or outer diameter of the sleeve section 11.

[0037] In the second axial area 5, second windows 16 are provided, which are designed as empty windows and which significantly contribute to a weight reduction of the sleeve section 11.

[0038] Also in the second axial area 5, third windows 17 are provided through which the third planet gears 8 project to engage with the ring gear 9. The outer diameter and / or outer circumference of the sleeve section 11 is dimensioned such that the third planet gears 8 project sufficiently far radially to engage with the ring gear 9. This, along with space and weight requirements, limits the outer diameter of the sleeve section 11. Consequently, the other planet gears 6, 7 project into or through the first window 15.

[0039] From a functional perspective, only the third windows 17 are necessary to enable a functional connection between the third planet gears 8 and the ring gear 9. The other windows 15, 16, however, as well as the first and second planet gears 6, 7, represent disruptive contours that cause the gear oil to splash when the planet carrier 3 rotates. This leads to an increase in resistance during rotation of the planet carrier 3 and consequently to a reduction in the efficiency of the planetary gear 1. A further problem can arise from the displacement of gear oil from the interior of the planet carrier 3, as the gear oil is then distributed uncontrollably under pressure within the planetary gear housing.

[0040] The Fig. Figure 2 shows the planetary gear 1 in the same representation as in Figure 1, with the difference that a cover assembly 18 is placed on the sleeve section 11 and covers the first windows 15 and the second windows 16. The cover assembly 18 closes the windows 15 and 16, so that, from a fluid dynamics perspective, they offer less resistance than in the uncovered state. The cover assembly 18 is formed by a plurality of cover elements 19, which are placed independently of one another on the planet carrier 3. The cover elements 19 can be made of sheet metal. In the present embodiment, they are made of plastic. The cover elements 19 are connected on both axial end faces to the first side plate section 10 and to the second side plate section 14, respectively, via a screw connection. The Fig. The cover element 19 shown in Figure 2 completely covers the first window 15 and rests adjacent to the sleeve section 11 in the direction of rotation. Furthermore, the cover element 19 also completely covers the second window 16 and rests on the sleeve section 11 in the second axial area 5 in the direction of rotation. In a radial plan view of the cover element 19, it is T-shaped, with the transverse leg of the T covering the first window 15 and thus the first and second planet gears 6, 7. The vertical leg of the T, on the other hand, covers the second window 16. The third window 17 remains uncovered so as not to interrupt the operative connection between the third planet gear 8 and the ring gear 9.

[0041] The cover element 19 can be divided into a base section 20 and a hood section 21. The hood section 21 covers the first planet gear 6, which projects into the first window 15 or even extends radially beyond the outer circumference of the sleeve section 11. The hood section 21 is convexly curved radially outwards. The base section 20 is formed by the remaining area of ​​the cover element 19 and has a cylindrical surface whose outer diameter is slightly larger, in particular by the material thickness of the cover element 19, than the outer diameter of the sleeve section 11. The base section 20 surrounds the hood section 21 in a U-shape. The transition between the base section 20 and the hood section 21 is formed by a curved flank, so that the flow resistance of the cover element 19 in this area is kept as low as possible.

[0042] The Fig. Figure 3 shows a radial top view of the cover element 19, which Fig. Figure 4 shows a radial bottom view of the cover element 19. The radial top view again shows the base area 20 and the hood area 21. At its axial end, the hood area 21 is closed off by a wall in the axial direction. Threaded blocks 22 are visible in the bottom view, providing threaded openings for screwing the cover element 19 to the planet carrier 3, in particular to the side disc sections 10, 14, with axially aligned screws. Reference symbol list 1 planetary gear 2 electric motors 3 planetary carriers 4 first axial area 5 second axial area 6 first planetary gears 7 second planetary gears 8 third planetary gears 9 Ring gear 10 first side window section 11 Sleeve section 12 Recording room 13 Partition wall 14 second side window section 15 first windows 16 second windows 17 third windows 18 Lid arrangement 19 Cover element 20 Basic area 21 Hood area 22 threaded blocks

Claims

[1] Planetary gear (1) with a planet carrier (3), wherein the planet carrier (3) has a first side disk section (10) and a sleeve section (11), wherein the first side disk section (10) and the sleeve section (11) form a receiving space (12) and wherein the planet carrier (3) defines a main axis of rotation (H), with a plurality of first planet gears (6), wherein the first planet gears (6) are arranged in a first axial region (4) of the planet carrier (3) in the receiving space (12), wherein the planet carrier (3) has first windows (15) in the sleeve section (11) in the first axial area (4), wherein the first windows (15) form passages for and / or to the first planet gears (6), wherein the planetary gear (1) has a cover arrangement (18) comprising a plurality of cover elements (19) for covering the first windows (15), characterized by , that the planet carrier (3) has a second window (16) as a blank window in a second axial area (5) in the sleeve section (11), and The lid elements (19) each cover a first and a second window (15, 16). [2] Planetary gear (1) according to claim 1, characterized by , that the cover arrangement (18) has hood areas (21) for covering the first planetary gears (6). [3] Planetary gear (1) according to any one of the preceding claims, characterized by , that the planetary gear (1) has a plurality of second planet gears (7), wherein the second planet gears (7) are arranged in the first axial region (4) of the planet carrier (3) in the receiving space (12), and that the first windows (15) are designed as double windows. [4] Planetary gear (1) according to any one of claims 1 to 3, characterized by , that the cover elements (19) are made of plastic or of sheet metal. [5] Planetary gear (1) according to any one of the preceding claims, characterized by , that the first side disc section (10) and the sleeve section (11) form a common pot and that the planet carrier (3) has a second side disc section (14), wherein the second side disc section (14) closes off the receiving space (12), wherein the cover elements (19) are each connected to both side disc sections (10,14). [6] Planetary gear (1) according to any one of the preceding claims, characterized by that this is designed as a differential device or as a distribution gear for an electric motor (2) in an electric axle for a vehicle.

Images