TRANSMISSION FOR AN INTEGRAL DIFFERENTIAL, INTEGRAL DIFFERENTIAL AND DRIVE TRAIN

Abstract

A transmission for an integral differential, the transmission having a fixed housing part, and a first planetary gear set defining an axis of rotation. The first planetary gear set has a planet carrier fixed to the fixed housing part to seal a lubricant chamber spatially delimited by the planet carrier and the fixed housing part, where at least a portion of the lubricant chamber extends around the axis of rotation. The first planetary gear set further includes planetary bearings, the planetary bearings being supplied with lubricant from the lubricant chamber. Moreover, the first planetary gear set includes planet gears, each of the planet gears being rotatably mounted on the planet carrier via at least one respective bearing of the planetary bearings. Additionally, the first planetary gear set includes a sun gear and a ring gear, each meshing with the planet gears.

Claims

1-21: (canceled)

22. A transmission (1) for an integral differential (10), comprising: a fixed housing part (9); and a first planetary gear set (6) defining an axis of rotation, the first planetary gear set (6) comprising: a planet carrier (2) fixed to the fixed housing part (9) to seal a lubricant chamber (8) spatially delimited by the planet carrier (2) and the fixed housing part (9), at least a portion of the lubricant chamber (8) extending around the axis of rotation; planetary bearings (7), the planetary bearings (7) being supplied with lubricant from the lubricant chamber (8); planet gears (3), each of the planet gears (3) being rotatably mounted on the planet carrier (2) via at least one respective bearing of the planetary bearings (7); a sun gear (4) meshing with the planet gears (3); and a ring gear (5) meshing with the planet gears (3).

23. The transmission (1) of claim 22, wherein the fixed housing part (9) is a transmission housing (11) of the transmission (1).

24. The transmission (1) of claim 22, wherein the fixed housing part (9) is a cover element (34) of the transmission (1).

25. The transmission (1) of claim 22, wherein the first planetary gear set (6) further comprises planet shafts (12) on the planet carrier (2), each of the planetary bearings (7) being rotatably mounted on a respective one of the planet shafts (12), each of the planet shafts (12) being fixed relative to the planet carrier (2) from within the lubricant chamber (8).

26. The transmission (1) of claim 22, wherein the first planetary gear set (6) further comprises planet shafts (12) on the planet carrier (2), each of the planetary bearings (7) being rotatably mounted on a respective one of the planet shafts (12), each of the planet shafts (12) having at least one of an axially extending duct (25) or a radially extending duct (26) for at least indirectly fluidically connecting the lubricant chamber (8) to the respective planetary bearing (7).

27. The transmission (1) of claim 26, wherein each of the planet shafts (12) defines an orifice bore as part of one or more of the at least one of the axially extending duct (25) or the radially extending duct (26).

28. The transmission (1) of claim 22, wherein at least a portion of one or both of the planet carrier (2) and the fixed housing part (9) is produced via casting.

29. The transmission (1) of claim 22, wherein the planet carrier (2) is rotationally fixed with respect to the fixed housing part (9) via a driving tooth system (13).

30. The transmission (1) of claim 29, wherein the driving tooth system (13) is within the lubricant chamber (8).

31. The transmission (1) of claim 29, wherein the driving tooth system (13) is defined by a side piece (2a) of the planet carrier (2) at a radially outer area of the side piece (2a) or a radially inner area of the side piece (2a).

32. The transmission (1) of claim 29, wherein the driving tooth system (13) is defined on an axial end face of the planet carrier (2).

33. The transmission (1) of claim 29, wherein the driving tooth system (13) only allows the planet carrier (2) to be installed in one position.

34. The transmission (1) of claim 22, wherein the planet carrier (2) is at least one of axially secured or centered by the fixed housing part (9).

35. The transmission (1) of claim 22, wherein a side of the fixed housing part (9) facing away from the lubricant chamber (8) conducts cooling medium.

36. The transmission (1) of claim 35, wherein the side of the fixed housing part (9) facing away from the lubricant chamber (8) has a surface structure (22), the surface structure (22) enlarging contact between the fixed housing part (9) and cooling medium.

37. The transmission (1) of claim 36, wherein the surface structure (22) is at least one of a honeycomb structure, a rib structure, or a pin-fin structure.

38. The transmission (1) of claim 22, wherein a side of the fixed housing part (9) facing the lubricant chamber (8) has a surface structure (23), the surface structure (23) enlarging contact between the fixed housing part (9) and lubricant.

39. The transmission (1) of claim 38, wherein the surface structure (23) is at least one of a honeycomb structure, a rib structure, or a pin-fin structure.

40. The transmission (1) of claim 22, further comprising a sealing element (24) between the planet carrier (2) and the fixed housing part (9), the sealing element (24) further sealing the lubricant chamber (8).

41. An integral differential (10) for a drive train (20) of a motor vehicle, the integral differential (10) comprising: the transmission (1) of claim 22, the transmission (1) further comprising a second planetary gear set (14) operatively connected to the first planetary gear set (6).

42. A drive train (20) for a motor vehicle, comprising: the integral differential (10) of claim 41; a first output shaft (16); a second output shaft (17); and a drive unit (15) which generates drive power distributed onto the first and second output shafts (16, 17) at least indirectly via the integral differential (10).

43. The drive train (20) of claim 42, wherein the drive unit (15) is an electric machine, the electric machine including a stator (19) fixed on a stator carrier (18), and a rotor (21) rotatable with respect to the stator (19), the stator carrier (18) being the fixed housing part (9) of the transmission (1).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0047] One preferred exemplary embodiment of the invention is explained in greater detail in the following with reference to the drawings, wherein identical or similar elements are labeled with the same reference characters, wherein:

[0048] FIG. 1 shows a simplified schematic longitudinal sectional view of a drive train according to example aspects of the invention, the drive train having a transmission according to example aspects of the invention, and

[0049] FIG. 2 shows a simplified schematic partial sectional view of the transmission according to example aspects of the invention.

DETAILED DESCRIPTION

[0050] Reference will now be made to embodiments of the invention, one or more examples of which are shown in the drawings. Each embodiment is provided by way of explanation of the invention, and not as a limitation of the invention. For example, features illustrated or described as part of one embodiment can be combined with another embodiment to yield still another embodiment. It is intended that the present invention include these and other modifications and variations to the embodiments described herein.

[0051] FIG. 1 shows a drive train 20 according to example aspects of the invention for a motor vehicle (not shown here). The drive train 20 is an electric axle drive including a drive unit 15, which is an electric machine. The drive unit 15 generates drive power and distributes the drive power onto two output shafts 16, 17 via an integral differential 10. The drive unit 15 has a stator 19, which is fixed in place on a stator carrier 18, and a rotor 21, which is rotatable relative to the stator 19.

[0052] The integral differential 10 of the drive train 20 has a transmission 1 that includes a first planetary gear set 6 and a second planetary gear set 14, which is operatively connected to the first planetary gear set 6. The two planetary gear sets 6, 14 are radially nested. Radial nesting saves axial installation space of the drive train 20. The differential 10 combines the function of transmission gearing and the differential function without first forming an axle torque, i.e., the cumulative torque of two wheel torques.

[0053] Both planetary gear sets 6, 14 are negative planetary gear sets in the present case and each includes a sun gear, a ring gear and a planet carrier as the gear set elements. In the present case, the first planetary gear set 6 is arranged radially outside the second planetary gear set 14, wherein the gear set elements of the first planetary gear set 6 include a sun gear 4, a ring gear 5, and a planet carrier 2. The first planetary gear set 6 has multiple planet gears 3, which are rotatably mounted on planet shafts 12 via planetary bearings 7. The planet shafts 12 in turn are non-rotatably mounted on the planet carrier 2. The planet carrier 2 of the first planetary gear set 6 is fixed to the housing. The ring gear 5 of the first planetary gear set 6 is connected to the first output shaft 16 for conjoint rotation. The gear set elements of the second planetary gear set 14 include a planet carrier 27, a sun gear 28, and a ring gear 29. The sun gear 4 of the first planetary gear set 6 is formed in one piece with the ring gear 29 of the second planetary gear set 14. The planet carrier 27 of the second planetary gear set 14 is connected to the second output shaft 17 for conjoint rotation. The drive unit 15 drives the sun gear 28 of the second planetary gear set 14. The sun gear 28 is connected to the rotor shaft 36 of the drive unit 15, which is an electric machine, for conjoint rotation. Alternatively, in some embodiments, the planetary gear sets 6, 14 are instead arranged axially adjacent to one another.

[0054] As is shown in FIG. 2 in greater detail, an annular lubricant chamber 8 for supplying the planetary bearings 7 with lubricant is arranged around an axis of rotation or the longitudinal axis of the first planetary gear set 6. The lubricant chamber 8 is formed or defined spatially between the planet carrier 2 and a fixed housing part 9. In other words, the lubricant chamber 8 is spatially delimited by the planet carrier 2 of the first planetary gear set 6 and by a fixed housing part 9. The planet carrier 2 of the first planetary gear set 6 comes to rest against the fixed housing part 9 so as to seal the lubricant chamber 8.

[0055] In the present case, the planet carrier 2 of the first planetary gear set 6 and the transmission housing 11 of the transmission 1 jointly form the circumferential lubricant chamber 8. Neither the lubricant nor the inlet to and outlet from the lubricant chamber 8 are shown here. Both the planet carrier 2 and the fixed housing part 9, i.e., the transmission housing 11 in the present case, are produced via casting, for example, by die casting. Recesses 31 are formed on or defined in the transmission housing 11, through which lubricant is conducted out of the lubricant chamber 8, which should be understood as an at least partially annular duct, to the planet shafts 12.

[0056] The axial support of the planet carrier 2 of the first planetary gear set 6 on the transmission housing 11 or on the fixed housing part 9 is used simultaneously to axially secure the planet shafts 12 in a first axial direction. The planet shaft 12 is prevented from shifting in the opposite direction by a pin 30 for axially securing the planet shaft 12. Starting from the longitudinal axis of the planet shaft 12, the pin 30 is inserted, extending substantially radially, into the planet shaft 12, in particular being pressed in, and projects beyond the outer diameter of the planet shaft 12, wherein the radially projecting section of the pin 3 prevents the planet shaft 12 from shifting to the left as shown in the present representation. Recesses 32 are also provided on the planet carrier 2 for the pins 30, the recesses in turn preventing the pins 30 from being able to radially move out of the planet shaft 12 after installation. Furthermore, the recesses 32, in combination with the pins 30, prevent the planet shafts 12 from turning in the planet carrier 2 in an undesirable manner.

[0057] Each planet shaft 12 has an axial duct 25 and two radially extending ducts 26 which are fluidically connected to the axial duct 25. The axial duct 25 is fluidically connected to the particular recess 31 defined in the transmission housing 11 and the radial ducts 26 are fluidically connected to the outer circumference of the planet shaft 12 and to the planet carrier 2. The radial ducts 26 directly adjoin or connect to the axial duct 25. The radially extending ducts 26 each have a smaller cross-section than the axially extending duct 25 and, as a result, each act as an orifice bore, by which a lubrication pressure is set at the planet carrier 2. Therefore, the planet shaft 12 defines an orifice bore as part of the radially extending duct 26.

[0058] The transmission housing 11 has a portion with an inner circumferential surface 33 into which the planet carrier 2 is axially inserted during assembly, such that the planet carrier 2 is centered with respect to the fixed housing part 9. The planet carrier 2 is therefore radially positioned in the transmission housing 11 by a centering device 38 mounted on an inner diameter of the transmission housing 11. The tolerance between the centering device 38 and the planet carrier 2 is selected such that the centering device 38 also functions as a sealing seat, the planet carrier 2 being pressed into the transmission housing 11. Alternatively, it is conceivable to provide the centering device 38 of the planet carrier 2 on the outer circumference of the planet carrier 2. In some instances, a seal is provided at the inner circumferential surface 33 between the planet carrier 2 and the transmission housing 11.

[0059] At its outer diameter, the planet carrier 2 is secured via a driving tooth system 13 against rotation with respect to the fixed housing part 9 or the transmission housing 11. The driving tooth system 13 is arranged on a side piece 2a of the planet carrier 2 in the radially outer region of the side piece 2a and is provided for non-rotatably accommodating the planet carrier 2 on the fixed housing part 9. In addition, the driving tooth system 13 protrudes from an axial end face of the planet carrier 2. More particularly, the driving tooth system 13 is formed (in a manner not shown in greater detail) as external toothing on the planet carrier 2 and as internal toothing on the fixed housing part 9. In the present case, the driving tooth system 13 is arranged in the main housing, i.e., on the transmission housing 11 of the transmission 1, wherein the transmission housing 11 in turn is connected to a chassis (not shown here) of the motor vehicle. As a result, it is not necessary to guide the transmission support torque introduced at the driving tooth system 13 away via further housing interfaces, such as, for example, a cover element 34.

[0060] The housing interface between the transmission housing 11 and the cover element 34, in particular the provided fasteners, is therefore slimmer.

[0061] The driving tooth system 13 is arranged within the lubricant chamber 8. A sealing element 24, such as an O-ring, is arranged spatially between the planet carrier 2 and the fixed housing part 9 in the region of the driving tooth system 13 or next to the driving tooth system 13, such that the sealing element 24 seals the lubricant chamber 8. The sealing element 24 is positioned such that the driving tooth system 13 is located in the lubricant chamber 8. As a result, torsional vibrations from the first planetary gear set 6 and load reversal shocks between the planet carrier 2 and the transmission housing 11 are damped, because lubricant must first be displaced for each micromovement. Also, while not shown in detail, the teeth of the driving tooth system 13 have irregular toothing geometries to avoid an incorrect installation of the planet carrier 2 on the housing component 9 or on the transmission housing 11. In this way, the planet carrier 2 is always inserted in the same desired angular position. Therefore, the planet gears of the first planetary gear set 6 are also always in the same position. The goal is to always ensure optimal lubrication of all planet gears 3.

[0062] The fixed housing part 9, i.e., the transmission housing 11 in this case, conducts a coolant on an axial side facing away from the lubrication chamber 8. The coolant or cooling medium dissipates heat from the lubricant chamber 8, through which lubricant flows, and simultaneously cools the drive unit 15. The axial side of the transmission housing 11 that conducts the cooling medium includes a first surface structure 22, which enlarges or maximizes a surface which is in contact with a cooling medium, and induces eddies in the cooling medium, with the eddies improving a transfer of heat from the fixed housing part 9 to the cooling medium. The axial side of the transmission housing 11 that conducts the cooling medium also include ducts 37 which conduct cooling medium. The fixed housing part 9 also has a second surface structure 23 on an axial side facing the lubricant chamber 8, the second surface structure 23 enlarging or maximizing a surface which is in contact with the lubricant and inducing eddies in the lubricant, the eddies improving a transfer of heat from the lubricant to the fixed housing part 9. Therefore, a transfer of heat from the annular lubricant chamber 8 to the coolant-conveying cooling circuit is improved due to the surface structures 22, 23 on the fixed housing part 9. The surface structures 22, 23 are formed as a honeycomb structure, a rib structure and/or as a pin-fin structure. In FIG. 2, the surface structures 22, 23 are ribs.

[0063] Any overflowing lubricant not branched off to the planetary bearings 7 emerges from the lubricant chamber 8 via the lubricant duct 35. The lubricant duct 35 is provided for cooling and lubricating further components of the drive train 20, in particular further components of the transmission 1 and of the drive unit 15. The lubricant duct 35 is composed of multiple fluidically interconnected duct sections which are provided in the cover element 34 already during casting and mechanically introduced into or cast in the transmission housing 11.

[0064] The invention is not limited to the disclosed embodiments. Other embodiments or variations result for a person skilled in the art within the scope of the utilization of the present invention and within the scope of a precise analysis of the drawings, the description and the patent claims. In particular, a person skilled in the art recognizes that the drive train 20, depending on the available installation space, may alternatively have the cover element 34 of the transmission 1 or the stator carrier 18 of the drive unit 15 provided as a fixed housing part 9, in order to form the lubricant chamber 8 together with the planet carrier 2.

[0065] Modifications and variations can be made to the embodiments illustrated or described herein without departing from the scope and spirit of the invention as set forth in the appended claims. In the claims, reference characters corresponding to elements recited in the detailed description and the drawings may be recited. Such reference characters are enclosed within parentheses and are provided as an aid for reference to example embodiments described in the detailed description and the drawings. Such reference characters are provided for convenience only and have no effect on the scope of the claims. In particular, such reference characters are not intended to limit the claims to the particular example embodiments described in the detailed description and the drawings.

REFERENCE CHARACTERS

[0066] 1 transmission [0067] 2 planet carrier of the first planetary gear set [0068] 2a side piece of the planet carrier [0069] 3 planet gear of the first planetary gear set [0070] 4 sun gear of the first planetary gear set [0071] 5 ring gear of the first planetary gear set [0072] 6 first planetary gear set [0073] 7 planetary bearing [0074] 8 lubricant chamber [0075] 9 fixed housing part [0076] 10 integral differential [0077] 11 transmission housing [0078] 12 planet shaft [0079] 13 driving tooth system [0080] 14 second planetary gear set [0081] 15 drive unit [0082] 16 first output shaft [0083] 17 second output shaft [0084] 18 stator carrier [0085] 19 Stator [0086] 20 drive train [0087] 21 Rotor [0088] 22 first surface structure [0089] 23 second surface structure [0090] 24 sealing element [0091] 25 axial duct [0092] 26 radial duct [0093] 27 planet carrier of the second planetary gear set [0094] 28 sun gear of the second planetary gear set [0095] 29 ring gear of the second planetary gear set [0096] 30 pin [0097] 31 recess in the fixed housing part [0098] 32 recess in the planet carrier [0099] 33 inner circumferential surface of the transmission housing [0100] 34 cover element [0101] 35 lubricant duct [0102] 36 rotor shaft [0103] 37 duct [0104] 38 centering device