Bevel gear differential with a star-shaped bearing plate

Abstract

A device (1) is proposed comprising a bevel gear differential (2), wherein the bevel gear differential (2) has at least one compensating gear (3) and two output gears (4), and the at least one compensating gear (3) has a bevel gear pin (5) for supporting the at least one compensating gear (3), wherein the supporting of the at least one compensating gear (3) with its bevel gear pin (5) is formed by a star-shaped bearing plate (6), the wall (7) of which is smaller in the axial direction than the diameter of the bevel gear pin (5), and the bearing plate (6) supports the end (8) of the bevel gear pin (5) oriented towards the axis of rotation of the bevel gear differential (2).

Description

The invention relates to a bevel gear differential with a star-shaped bearing plate. DE 10 2007 040 479 A1 discloses a differential gear with a sum shaft for distributing torques to a first differential member and to a second differential member via at least one planetary bevel gear, wherein the planetary bevel gear is operatively connected in such a way that the planetary bevel gear is in tooth mesh with a first toothing on the first differential member and with a second toothing on the second differential member, wherein the axis of rotation of the planetary bevel gear is perpendicular to the axis of rotation of the sum shaft and the axis of rotation of each differential member, wherein the sum shaft is designed as a spur gear in which the at least one planetary bevel gear is mounted. WO 2020 069 692 A1 discloses a differential with differential gears, a drive gear and at least one cover, wherein the drive gear has external circumferential toothing around an axis of rotation and is provided with bearing points on the inside, the differential gears are mounted at the bearing points in the drive gear and the differential is closed on one side with the cover, wherein the differential gears are held in the drive gear by means of the cover and that the cover and the drive gear are attached to each other without the effect of any further fastening means only by at least one material-fit connection in such a way that at least the differential formed from the differential gears, the drive gear and the cover is a self-supporting unit. DE 10 2023 121 334 A1 shows a bevel gear bolt star in a one-piece design. DE 30 00 128 A1 discloses a differential reduction gear with double reduction for a drive axle of a motor vehicle, in particular for trucks, comprising a carrier rigidly connected to the axle shaft housings, a bevel pinion driven by the vehicle transmission output shaft, a sleeve rotatable about the axis of the two drive wheels and supported by the carrier, a first bevel gear crown attached to the outside of the sleeve and meshing with the bevel pinion, a second bevel gear crown attached to the inside of the sleeve, a third bevel gear crown arranged opposite these and attached to the carrier, a two-part satellite carrier rotatable inside the sleeve, two rows of cylindrical journals with common axes orthogonal to the axes of the drive wheels, wherein the journals of each row are formed integrally with an inner carrier body and both inner carrier bodies are positively connected to each other, and each is connected on the outside to second and third bevel gears respectively.The internal structure comprises conical planetary gears meshing with conical satellite gears. The conical planetary gears mesh with conical planetary gear carriers mounted on the axle shafts. A differential bolt in bevel gear differentials with one-piece, three-armed bevel gear bolts is known in the prior art. The task is to improve the existing bevel gear differential. The problem is solved according to the invention by a device with a bevel gear differential, wherein the bevel gear differential has at least one differential gear and two output gears and the at least one differential gear has a bevel gear pin for bearing the at least one differential gear, in that the bearing of the at least one differential gear with its bevel gear pin is formed by a star-shaped bearing plate, the wall of which is smaller in the axial direction than the diameter of the bevel gear pin and the bearing plate supports the end of the bevel gear pin oriented towards the axis of rotation of the bevel gear differential. At least one compensating gear comprises exactly one or more compensating gears, each compensating gear having its own bevel gear pin. The bevel gear pin can be rotationally fixed to the compensating gear, or the compensating gear can be rotatably mounted on the bevel gear pin. The bevel gear bolt - and thus indirectly also its compensating gear - is received at least at one end of the bevel gear bolt by the bearing plate through a specially provided receptacle. The wall thickness of the bearing plate (in the axial direction of the bevel gear differential, i.e., along the axis of rotation of the bevel gear differential) is smaller than the diameter of at least one bevel gear pin. This saves axial installation space according to the invention. The bearing plate supports the end of the bevel gear pin oriented towards the axis of rotation of the bevel gear differential. If several bevel gear pins are supported by the bearing plate with their ends oriented towards the axis of rotation, the bearing plate advantageously replaces the bevel gear pin star known from the prior art and, due to its plate-like design, provides more axial installation space, allowing the bevel gear differential to be built smaller in the axial direction. The freed-up installation space can, for example, optimize the lubricant flow, especially at low temperatures. Thus, a single assembly consisting of the bevel gear pin and the bearing plate is formed. In addition to the space savings achieved by the invention, the bevel gear pin bearing becomes more economical thanks to the bearing plate, since the bearing plate can be designed as a stamped or fine-blanked sheet metal part. Particularly when combining a bevel gear differential with a planetary gear set featuring stepped planets, a further advantage arises in the mounting of the bevel gear differential. When integrating bevel gear differentials with such planetary gear sets, the use of three compensating bevel gears leads to the maximum possible axial nesting, since at least one compensating gear can be positioned circumferentially between two planets of the planetary gear set. Therefore, the bevel gear differential should, in this context, be at least partially positioned within the smaller step of the stepped planet. Furthermore, according to the invention, it is advantageous with regard to power transmission that the torque is introduced directly into the center of the bevel gear differential and that the bearing plate according to the invention allows the use of three simple, cylindrical bevel gear bolts, preferably of identical design. The circumferential power transmission from one bevel gear bolt to another advantageously occurs via the area of ​​the radially projecting tip of the star-shaped bearing plate. The radially projecting tip(s) can be designed differently. The design of a simple cylindrical bevel gear bolt, made possible by the bearing plate and advantageously inserted into a recess in the bearing plate, eliminates the need to construct the planet carrier of the planetary gear and / or the housing part of the bevel gear differential in multiple parts to axially fix the bevel gear bolt using two components. Closed receptacles for the bevel gear bolt can be incorporated into the planet carrier or the housing part of the bevel gear differential, thereby improving the force transmission from the planet carrier or housing part to the bevel gear bolt. The cylindrical portion of the bevel gear bolt can thus preferably be inserted in a bore. The fully enclosed relocation of the cylindrical portion of the bevel gear bolt within the bore by a single component allows for the creation of a bore bearing, enabling higher load capacities or smaller dimensions. The planet carrier of the planetary gear set and / or the housing part of the bevel gear differential no longer need to be designed as a single unit or in two parts to accommodate the bevel gear pin. This can now be accomplished by a single component consisting of a bearing plate and a bevel gear pin. Due to its plate-like design, the bearing plate according to the invention has the advantage that the applied torque can be supported closer to the force application point in the planet carrier / housing part on the bevel gear pin - with an almost constant mass of the assembly consisting of bevel gear pin and bearing plate compared to the one-piece bevel gear pin star from the prior art. The invention advantageously enables a simple bore for receiving the bevel gear pin in the planet carrier / housing part instead of milling and the higher torque transmission performance through the closed geometry formed by a component on the bevel gear pin. According to the invention, the bearing plate and the bevel gear pins engage with each other via a bearing receptacle and form a demountable assembly. This facilitates the installation of the bevel gear pins in fully cylindrical receptacles, for example radial bores, of a planetary gear carrier. In a first embodiment of the invention, the bearing receptacle is designed as a slot in the bearing plate. Torque in the circumferential direction can be transmitted between the bevel gear pin and the bearing plate via a line contact through the slot in the bearing plate. In a second embodiment of the invention, the bearing receptacle is designed as a slot in the bevel gear pin. The bevel gear pin thus rides on the bearing plate. Torque transmission is now preferably introduced into the bevel gear differential only via the star-shaped bearing plate from a planetary gear set. Preferably, the bevel gear pins are inserted into a fully cylindrical recess in the planet carrier. Thus, in contrast to the slot-shaped recess known in the prior art, an idealized line contact is no longer formed, but rather a surface contact, which reduces the load at this contact point and allows either the dimensional design to be reduced or an increased load transmission to be achieved. In a further embodiment, the device also includes a planetary gear unit upstream of the bevel gear differential as a load stage, wherein the torque of the planetary gear unit is introduced into the bearing plate via the load stage bolts of the planetary gear unit. Continuing this design, the bearing plate has annular extensions arranged on its star-shaped base to absorb the torque. These extensions are in direct engagement with the load-stage bolts. The annular extensions, projecting radially from the star shape of the bearing plate, have an axial through-bore into which the end of the load-stage bolt can engage. One load-stage bolt is also supported by the planet carrier of the planetary gear set and carries a stepped planet. Advantageously, the force is thus transmitted directly and immediately from the load-stage bolt to the annular extension and therefore to the bearing plate. In an alternative embodiment, the device further comprises a planetary gear unit upstream of the bevel gear differential as a load stage, wherein the torque of the planetary gear unit is introduced into the bearing plate via the planet carrier of the planetary gear unit. Continuing this alternative design, the bearing plate has star-shaped extensions arranged on its star-shaped surface to absorb the torque. These extensions are in direct engagement with the planet carrier. The radial extensions projecting from the star shape of the bearing plate have an end form that engages in a recess complementary to the planet carrier. The engagement of the star extension in this recess transmits the torque from the planetary gear set to the bearing plate and thus into the bevel gear differential. Advantageously, the force is thus transmitted directly and immediately from the planet carrier to the star extension and therefore to the bearing plate. In one embodiment of the invention, the bearing plate can have a crank in the axial direction at its star-shaped ends. This allows for greater design freedom in the axial positioning of the bearing plate relative to the torque application by a planetary gear unit according to the aforementioned embodiments. Since the bearing plate is preferably made from a sheet metal part, both the outer star shape and a crank can be easily formed. Character description Further embodiments of the invention are explained in more detail with reference to the figures. These show: Fig. 1 the prior art of a combined transmission consisting of a reduction stage with planetary gears and a bevel gear nested therein; Fig. 2 a cross-section along section line AA of the transmission from Fig. 1 with a view of the bevel gear pin star; Fig. 3 a first embodiment of the assembly according to the invention, consisting of a bevel gear pin and a bearing plate, installed in a combined transmission; Fig. 4 the first embodiment according to Fig. 3 of the assembly according to the invention, consisting of a bevel gear pin and a bearing plate; Fig. 5 a cross-section along section line BB according to Fig. 3; Fig. 6 a cross-section along section line CC according to Fig. 3; Fig. 7 a second embodiment of the assembly according to the invention, consisting of a bevel gear pin and a bearing plate; and Fig. 8 a cross-section through a combined transmission from Fig.5 with the installed second embodiment according to Fig. 7 . Fig. 1 shows the prior art of a combined transmission consisting of a reduction stage with planetary gears and a bevel gear nested therein. Such a design, in particular of the one-piece bolt star 16, is known from the prior art, for example from DE 10 2023 121 334 A1 or DE 10 2023 132 367 A1. The reduction gear is designed as a planetary gear 9 with stepped planets 10, and the bevel gear is a bevel gear differential 2, both of which are enclosed by the device 1. The device 1 comprises a planet carrier 11 of the planetary gear 9 and a housing part 12 of the bevel gear differential 2. The planet carrier 11 carries several stepped planets 10. The housing part 12 is rotationally fixed to the planet carrier 11. The planet carrier 11 carries one of the output gears 4 of the bevel gear differential 2 and thus also constitutes a housing part of the bevel gear differential 2. The device 1 rotates about a pivot axis 13. The device 1 is used in electromechanical axle drive trains where the electric motor is arranged coaxially with the gearbox. Preferably, to achieve a high power density, the device 1 has three stepped planets 10 of the planetary gear set 9 and three differential gears 3 of the bevel gear differential 2, wherein the differential gears 3 and the stepped planets 10 are arranged alternately relative to each other in the circumferential direction and partially overlap in the axial direction – along the axis of rotation 13 – and thus both gearboxes (planetary gear set 9 and bevel gear differential 2) are nested within each other. The bolt star 16 is inserted into the receptacles 15 of the planet carrier 11 by being axially guided to the planet carrier 11. For this to occur, the receptacles 15 must be open in the axial direction to allow access of the bolt star 16 to the receptacle 15. To axially secure the bolt star 16, in this embodiment each axially open side of the receptacle 15 is covered by the housing part 12, thus locking the bolt star 16 in its axial direction of movement. Fig. 2 shows a cross-section along section line AA of the gear unit from Fig. 1, looking towards the bolt star 16. The star-shaped design of the bolt star 16 is clearly visible, with three cylindrical extensions projecting radially from its center, offset from each other at an angle of 120°. The conical compensating gears 3 are mounted onto the bolt star 16, and then the bolt star 16 is inserted into the receptacles 15. Each receptacle 15 is positioned on the bisector of the angle between the angular positions of two stepped planets 10. Fig. 3 shows a first embodiment of the assembly according to the invention, consisting of a bevel gear pin 5 and a bearing plate 6, installed in a combined transmission. The combined transmission shown in Fig. 1 was adopted for illustrative purposes. The device 1 thus comprises the reduction gear, designed as a planetary gear 9 with stepped planets 10, and the bevel gear differential 2. The difference to the embodiment according to Fig. 1 and Fig. 2 lies in the bearing plate 6 according to the invention with separately formed bevel gear bolts 5 instead of the bolt star 16. By using the bearing plate 6, axial installation space can be freed up in the center near the axis of rotation 13 compared to the prior art solution, which can then be used, for example, to improve lubricant flow in the bevel gear differential 2. The bearing plate 6 is preferably a stamped or fine-blanked sheet metal part. The bearing plate 6 according to the invention introduces the torque directly into the center of the bevel gear differential 2 and enables the use of cylindrical bevel gear pins 5 as individual components, which are significantly simplified in their manufacture. The bearing plate 6 has annular extensions 18 integrally molded into it, each annular extension 18 being associated with a load-stage pin 17. Each annular extension 18 has a circular bore 19 adapted to the outer surface of the load-stage pin 17, into which the load-stage pin 17 engages. Since the load-stage pin(s) 17 transmit the torque from the planetary gear 9 to the bevel gear differential 2, improved power transmission is now possible, as this does not occur via the planet carrier 11 of the planetary gear 9 or a housing part 12 of the bevel gear differential 2, but rather via a bore formed between the load-stage pin 17 and the bore 19. Furthermore, due to the simple cylindrical components of the bevel gear pin 5, the receptacles 15 can be designed as radial bores instead of as U-shaped slots open axially on one side, as in Fig. 1 and Fig. 2. This also creates a bore, which significantly improves the contact and load between the bevel gear pin 5 and its receptacle 15. In this embodiment, however, the U-shaped, slot-like recess 15 from Figures 1 and 2 has been adopted in the illustration in the first step, since the torque is already introduced into the bevel gear differential 2 much more effectively via the annular extensions 18. Therefore, the assembly parting line 14 also remains in this embodiment. The transmission of the torque via the annular extensions 18 relieves the load on the transmission contact between the bevel gear pins 5 in the receptacles 15. Fig. 4 shows the first embodiment of the assembly according to the invention, consisting of bevel gear pins 5 and bearing plate 6 as shown in Fig. 3. In this embodiment, the bearing plate 6 is triangular in shape and has annular projections 18 at the vertices of the triangle and bearing receptacles 20 for the bevel gear pins 5 on the side edges of the triangle. The bearing receptacles 20 are configured either, in a first variant, such that the bearing plate 6 has a slot for each bevel gear pin 5 into which the bevel gear pin 5 is inserted, or, in a second variant, such that the bevel gear pin 5 has a slot at its end with which the bevel gear pin 5 is mounted onto the bearing plate 6. Advantageously, in the second variant, the bevel gear pin 5 is secured against rotation relative to the bearing plate 6, so that the flats 21 formed by the bevel gear pin 5 for oil guidance into the compensating gear 3 always maintain their optimal orientation.In the first variant, the bevel gear pin 5 can rotate in the slot of the bearing plate 6 about its own axis of symmetry, thereby improving the power transmission to both the bearing plate 6 and the receptacle 15 of the planet carrier 11 through any contact changes and increasing the service life. In the radial direction from the bearing plate 6 to the individual annular processes 18, the plate has a crank 22. This allows the part “bearing plate 6” to be offset from the part “annular process 18” in the axial direction. Fig. 5 shows a cross-section along section line BB according to Fig. 3. The cross-section allows a view into the interior of the bevel gear differential 2, looking towards the planetary gear set 9, which is recognizable by the visible stepped planets 10. The bevel gear pins 5 are each inserted into the receptacles 15 formed by the planet carrier 11 and bear at least circumferentially in this receptacle 15 so that a torque can be transmitted from the planet carrier 11 to the bevel gear differential 2. The bearing plate 6 has three receptacles 20, each of which engages with a bevel gear pin 5. The bearing receptacles 20 are slot-shaped, as already explained with the first variant in the description of Fig. 4. The bearing plate 6 is axially fixed by the annular extensions 18, which are cut away here. Fig. 6 shows a cross-section along section line CC according to Fig. 3. The annular extensions 18, visible in this section plane as a preferably single-material part of the bearing plate 6, engage the ends of the load-step bolts 17 – each annular extension 18 engages one load-step bolt 17. Each annular extension 18 has a bore 19 into which the load-step bolt 17 engages. This allows the torque to be transmitted directly from the load-step bolts 17 to the annular extensions 18 and thus to the bearing plate 6. This relieves the contact between the bevel gear bolt 5 in its receptacle 15 and thus also the area around the receptacle 15 and the planet carrier 11. The slot-shaped bearing receptacles 20 are also clearly visible, and due to the perspective, they are spaced away from the bevel gear pin 5 in this section plane. Thus, it is clear from the illustration in Fig. 5 that the bevel gear pin 5 forms a linear contact with its bearing receptacle 20. Fig. 7 shows a second embodiment of the assembly according to the invention, consisting of bevel gear pins 5 and bearing plate 6. In this second embodiment, the bearing plate 6 is also triangular in shape, but unlike the embodiment according to Fig. 4, it does not have annular projections 18 at the vertices of the triangle. The bearing receptacles 20 for the bevel gear pins 5, which are present on the side edges of the triangle, have been retained. The bearing receptacles 20 are either, in a first variant, such that the bearing plate 6 has a slot for each bevel gear pin 5 into which the bevel gear pin 5 is inserted, or, in a second variant, such that the bevel gear pin 5 has a slot at its end with which the bevel gear pin 5 is fitted onto the bearing plate 6. The first variant is shown in this illustration. The star-shaped ends of the bearing plate 6 are designed as star extensions 23. An axial curvature is not present here, but is possible. Fig. 8 shows a cross-section through a combined transmission from Fig. 5 with the second embodiment shown in Fig. 7. The combined transmission shown in Fig. 1 was used for illustrative purposes. Referring to the special feature of the second embodiment in Fig. 7, namely the bearing plate 6 with the star projections 23, the star projections 23 can engage in complementary receptacles 24 of the planet carrier 11, which are designed to be suitable for torque transmission. Thus, the torque from the planetary gear 9 can be transmitted directly via the planet carrier 11 to the bearing plate 6 and into the bevel gear differential 2 as a load-stage transmission. Reference symbol list 1 Device 2 Bevel gear differential 3 Compensating gear 4 Output gear 5 Bevel gear bolt 6 Bearing plate 7 Wall 8 End 9 Planetary gear 10 Stepped planet 11 Planet carrier 12 Housing part 13 Shaft of rotation 14 Assembly parting line 15 Bolt receptacle 16 Bolt star 17 Load stage bolt 18 Ring extension 19 Bore 20 Bearing receptacle 21 Flattened section 22 Offset 23 Star extension

Claims

Device (1) with a bevel gear differential (2), wherein the bevel gear differential (2) has at least one differential gear (3) and two output gears (4), and the at least one differential gear (3) has a bevel gear pin (5) for supporting the at least one differential gear (3), wherein the support of the at least one differential gear (3) with its bevel gear pin (5) is formed by a star-shaped support plate (6), the wall (7) of which is smaller in the axial direction than the diameter of the bevel gear pin (5), and the support plate (6) supports the end (8) of the bevel gear pin (5) oriented towards the axis of rotation of the bevel gear differential (2), characterized in thatthat the bearing plate (6) and the bevel gear pins (5) engage with each other via a bearing receptacle (20) and form an assembly, and either the bearing receptacle (20) is designed as a slot in the bearing plate (6) or the bearing receptacle (20) is designed as a slot in the bevel gear pin (5). Device (1) according to one of the preceding claims, characterized in that the bevel gear pins (5) are inserted in a fully cylindrical receptacle (15) of the planet carrier (11). Device (1) according to one of the preceding claims, characterized in that the device (1) further comprises a planetary gear (9) as a load stage upstream of the bevel gear differential (2), wherein the torque of the planetary gear (9) is introduced into the bearing plate (6) via the load stage bolts (17) of the planetary gear (9). Device (1) according to claim 3, characterized in that the bearing plate (6) has annular extensions (18) arranged on the star shape of the bearing plate (6) for receiving the torque, which are in direct engagement with the load step bolts (17). Device (1) according to one of the preceding claims, characterized in that the device (1) further comprises a planetary gear (9) as a load stage upstream of the bevel gear differential (2), wherein the torque of the planetary gear (9) is introduced into the bearing plate (6) via the planet carrier (11) of the planetary gear (9). Device (1) according to claim 5, characterized in that the bearing plate (6) has star extensions (23) arranged on the star shape of the bearing plate (6) for receiving the torque, which are in direct engagement with the planet carrier (11). Device (1) according to one of the preceding claims, characterized in that the bearing plate (6) has a crank (22) at its star-shaped ends in the axial direction.

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