Gear arrangement and drive train with such a gear arrangement

Abstract

The invention relates to a transmission arrangement (1) for a drive train (2) of a vehicle, comprising a planetary gear set (4) with a planet carrier (5) on which at least one bolt (6) is arranged, wherein a first bearing element (7) for rotatably mounting a planet gear (8) is arranged on the bolt (6), wherein the transmission arrangement (1) further comprises a differential (9) effectively connected to the planet carrier (5) for driving purposes, which transmits a drive power acting on the planet carrier (5) to a first central shaft (10) and a second central shaft (11) arranged coaxially thereto, wherein at least the first central shaft (10) has a central first channel (12) for supplying cooling and / or lubrication to an interior (13) of the differential (9), wherein at least one first bore (14) extending radially at least partially is formed on the planet carrier (5).to guide the cooling and / or lubricating medium from the interior (13) of the differential (9) into a second channel (15) of the bolt (6). Furthermore, the invention relates to a drive train (2) for a vehicle with such a transmission arrangement (1).

Description

[0001] The invention relates to a transmission arrangement for a drive train and a drive train for a vehicle with such a transmission arrangement.

[0002] DE 10 2021 112 967 B3 discloses a lubricant supply system for a drive device of an electrically powered vehicle having at least one electric motor, wherein the electric motor drives at least one vehicle wheel via a transmission arrangement. An electric motor hydraulic circuit is provided, in which a lubricant tank is connected via a suction line to a pressure pump, which pumps lubricant to the electric motor via an electric motor supply line. Furthermore, a transmission hydraulic circuit is provided, via which lubricant can be pumped to the transmission arrangement. The pressure pump, as a common pressure pump, is assigned to both the electric motor hydraulic circuit and the transmission hydraulic circuit, so that, during pump operation, lubricant can be circulated in both the electric motor hydraulic circuit and the transmission hydraulic circuit.The electric machine hydraulic circuit and the transmission hydraulic circuit have a lubricant sump and a return pump as further common components. The transmission arrangement has an axle differential, which is drivingly connected to the vehicle wheels on both output sides via flanged shafts. Furthermore, one of the flanged shafts is divided into a wheel-side shaft section and an axle-side shaft section, which can be coupled to one another via a separating clutch. The lubricant supply system also has a separating clutch hydraulic circuit, via which the separating clutch can be supplied with lubricant. The lubricant can be fed to the separating clutch via at least one separating clutch supply line. Lubricant flowing from the separating clutch collects in the shared lubricant sump.

[0003] To facilitate machining for a lubricating oil passage and to realize a power transmission device that can properly supply oil to an oil channel within a planetary pinion while preventing the entire device from being excessively large in an axial direction, JP 2018-189193 A discloses the following: A planetary gear set includes a carrier for rotatably supporting a planetary gear on a planetary pinion. A differential gear set includes a differential case formed integrally with the carrier. An oil passage is formed within the planetary pinion, which has an opening portion on a second side. A communication channel is formed in the differential carrier, via which an interior of the differential carrier and the opening portion of the oil passage in the planetary pinion communicate with each other.

[0004] Document JP 2018-189192 A discloses a drive device for a vehicle in which a radial dimension is reduced. This is achieved by a drive device for a vehicle comprising: a rotating electric machine serving as a driving power source for wheels; a first output member drivingly connected to a first wheel; a second output member drivingly connected to a second wheel; and a differential gear device for distributing a driving power from the rotating electric machine to the first output member and the second output member. The differential gear device, the first output member, and the second output member are arranged coaxially with the rotating electric machine. A first output speed reducing device is provided by means of a planetary gear between a first distributor output member and the first output member of the differential gear device.A second output speed reducer is provided by a planetary gear between a second distribution output element and the second output member of the differential gear device, and the first output speed reducer and the second output speed reducer are arranged coaxially with the rotating electric machine.

[0005] Document WO 2018 / 207557 A1 discloses a differential gear device in which a dedicated oil channel is formed in each pair of rotating output shafts. The differential gear is provided with a connecting member to which the pair of rotating output shafts are connected in opposite directions, allowing them to rotate relative to each other.

[0006] A connecting oil passage is formed in the connecting member to establish communication between the internal shaft oil passages in the pair of rotating output shafts.

[0007] The object of the present invention is to provide a transmission assembly with an improved coolant or lubricant supply, which, in particular, requires fewer oil pressure bores in an internal central shaft for supplying the components of transmission components to be cooled or lubricated. This object is achieved by a transmission assembly having the features of independent patent claim 1 and by a drive train having the features of patent claim 8. Advantageous embodiments are the subject of the dependent claims, the following description, and the figures.

[0008] A transmission arrangement according to the invention for a drive train of a vehicle comprises a planetary gear set with a planet carrier on which at least one bolt is arranged, wherein a first bearing element for the rotatable mounting of a planet gear is arranged on the bolt, wherein the transmission arrangement further comprises a differential which is drivingly connected to the planet carrier and which transmits a drive power acting on the planet carrier to a first central shaft and a second central shaft arranged coaxially thereto, wherein at least the first central shaft has a central first channel for supplying coolant and / or lubricant to an interior of the differential, wherein at least one first bore which extends radially at least in sections is formed on the planet carrier in order to guide the coolant and / or lubricant from the interior of the differential into a second channel of the bolt.

[0009] Due to diameter limitations imposed by the drive unit of the drive train, which is particularly designed as an electric machine, or other limiting structures of the drive train, it is not possible to arbitrarily increase the diameter of the central shafts in order to compensate for the increased stress concentration at the cross bores of the central shafts. However, the gear arrangement proposed here can reduce the number of cross bores on the first central shaft subjected to pressurized oil, because the coolant or lubricant can be supplied via the differential, the interior of which is flooded via the first channel of the first central shaft. A certain amount of coolant or lubricant is therefore accumulated in the differential and distributed from there or, in particular, passed on to the bearings and gearing of the planetary gear set.

[0010] In addition to the planet carrier and the at least one planet gear, the planetary gear set further comprises a sun gear and a ring gear, wherein the planet gear meshes with the sun gear and the ring gear. A "planetary gear set" is understood in particular to be a unit with a sun gear, a ring gear, and several planetary gears guided by a planet carrier on a circular path around the sun gear. Advantageously, each planetary gear set has exactly one stationary gear ratio. While the planet carrier forms the output component of the planetary gear set, the planetary gear set can be driven via the sun gear or the ring gear, while the other component is preferably arranged fixedly with the housing and thus rotationally fixed. In one exemplary embodiment, the sun gear is operatively connected to a drive unit, such as an electric machine or an internal combustion engine, and the ring gear is fixed.The planetary gear set converts the input drive power and drives the differential housing. The planetary gear set is part of a planetary transmission, which can also include additional planetary gear sets.

[0011] In addition to the differential housing, the differential comprises an axle in the form of a bolt or a shaft with a circular cross-section. The axle is fixedly arranged in the differential housing, with at least one spur gear, preferably two spur gears, in the form of a differential bevel gear being rotatably arranged on the axle. Both spur gears each mesh with a first axle gear, which is connected in a rotationally fixed manner to the first central shaft, and with a second axle gear, which is connected in a rotationally fixed manner to the second central shaft. The rotationally fixed connection is preferably made via a spline. The central shafts are to be understood as output shafts of the drive train, via which the wheels of the vehicle axle can be driven. The central shafts are therefore designed to be drivingly connected at least indirectly to an associated wheel of the vehicle.

[0012] The planetary gear set and the differential form a single geometric unit. This means that parts of the planetary carrier can assume functions of the differential, particularly the differential housing, and / or parts of the differential can assume functions of the planetary carrier. Accordingly, the differential housing rotates along with the planetary carrier.

[0013] When the planetary carrier and differential housing rotate about their rotational axes, the spur gears also rotate about the planetary carrier's rotational axis. The spur gears can also rotate about their own axis, i.e., about the longitudinal axis of the minor axle. The spur gears ensure that the wheel axles can rotate at different speeds, while the torque and rotational motion continue to be transmitted to the components connected to the wheel axles or central shafts, especially the vehicle's wheels.

[0014] When the vehicle is traveling in a straight line, the power is applied equally to both wheels on the vehicle's axle, so that the spur gears do not rotate on their own axis, as they rotate with the differential housing. They transfer the torque to the axle gears, causing them to rotate and thus indirectly drive the wheels. When the vehicle is cornering, however, the spur gears both rotate forward, but at different speeds, due to the different speeds of the wheel axles or central shafts. The speed difference between the axle gears is inversely proportional. In a further development, the differential can be designed as a limited-slip differential, whereby the differential can include corresponding coupling elements to couple the central shafts to one another.

[0015] The first channel, which is preferably located on the axis of rotation of the first central shaft, is designed to be fluidically connected to a coolant and / or lubricant supply. Coolant or lubricant is therefore pumped at least indirectly into the first channel by means of a pump and introduced via the first channel into the gear arrangement, specifically into the interior of the differential, wherein the coolant or lubricant is distributed from the interior of the differential to the components of the planetary gear set that are to be cooled or lubricated. The interior is understood to be the space of the differential that is spatially delimited by the spur gears, the axle gears and the end faces of the central shafts. The axis of the differential extends through the interior of the differential. The entire coolant and lubricant system is contained in the interior.Lubricant is collected and, with the help of the centrifugal forces acting, distributed outwards to the gears and bearing elements of the transmission arrangement, in particular the planetary gear set.

[0016] The first bore is arranged on the planet carrier in such a way that coolant or lubricant can be collected from the interior of the differential and guided to the second channel of the pin, wherein the second channel guides the coolant or lubricant to the first bearing element, which rotatably supports the planetary gear. The second channel can have axial and radial sections, depending on where the first bore opens into the second channel. The first bore has at least one radial component, so that the first bore is to be understood as a transverse bore. This is understood by the expression “extending radially at least in sections”. The first bore can additionally have an axial component, so that the first bore can also be designed in the form of an oblique bore, at least in sections. The first bore can also have axially extending sections, although the coolant or lubricant is generally guided radially outwards.Accordingly, an optional section is configured to receive coolant or lubricant from a radial section of the first bore and / or to convey it to a radial section of the first bore.

[0017] Since in this design the differential and the planetary carrier function as a geometric unit, all oil that collects in the differential can escape through at least the first hole in the planetary carrier and thus reaches the bearing elements and gears that need to be cooled or lubricated.

[0018] The first central shaft is arranged radially within the planetary gear set. The first central shaft is arranged coaxially with the longitudinal axis of the planetary gear set. The first central shaft is arranged radially within a sun gear and an input shaft of the transmission assembly. The input shaft is configured to transmit drive power from a drive unit to the transmission assembly. The first central shaft is arranged radially within the planetary carrier.

[0019] According to the invention, the planetary carrier has an axial section on which a sun gear of the planetary gear set is rotatably mounted via at least one second bearing element. The axial section of the planetary carrier can be arranged radially between the first central shaft and the first sun gear.

[0020] According to the invention, at least one second bore extending radially at least in sections is formed on the axial section of the planet carrier in order to supply the second bearing element with coolant and / or lubricant. The second bearing element can be a radial bearing, in particular a needle bearing or plain bearing. Radial forces are transmitted between two components by means of the radial bearing. A needle bearing or plain bearing saves radial installation space. The second bearing element is preferably arranged radially between the axial section of the planet carrier and the sun gear. The second bearing element and the second bore can lie in a common radially extending plane. In other words, the second bearing element and the second bore are arranged at the same axial position.

[0021] Furthermore, at least one third bore extending radially at least in part is preferably formed on the axial portion of the planet carrier to supply coolant and / or lubricant to a third bearing element for supporting the sun gear on the planet carrier. The third bearing element is preferably an axial bearing, in particular a cylindrical roller bearing. Axial forces can be transmitted between two components by means of an axial bearing.

[0022] The third bore is preferably configured to further supply a first toothing between the sun gear and the planet gear of the planetary gear set with coolant and / or lubricant. Thus, the third bearing element and the first toothing between the sun gear and the planet gear of the planetary gear set are lubricated or cooled via the third bore.

[0023] In one embodiment, the second bore and / or the third bore are fluidically connected to the interior of the differential via a spline between the first central shaft and a meshing first axle gear of the differential. In other words, a portion of the coolant or lubricant is guided from the interior of the differential via the spline, which connects the first central shaft to the first axle gear in a rotationally fixed manner, to the axial section of the planet carrier, where it can be further distributed via the second or third bore. During operation of the drive train, gaps form on the tooth flanks of the spline, depending on the direction of torque, through which gaps the coolant or lubricant can flow from one end of the spline to the other.Optionally, individual teeth of the internal toothing of the first axle gear and / or the external toothing of the first central shaft can be missing on the spline in order to be able to direct a desired volume of coolant or lubricant to the required location.

[0024] The first bore of the planetary carrier is preferably fluidically connected to the interior of the differential via a second toothing between a first differential bevel gear and a meshing first axle gear of the differential. In other words, a portion of the coolant or lubricant from the interior of the differential is guided via the second toothing to the first bore, through which it reaches the second channel of the pin.

[0025] In a further development of the invention, a perforated end plate is arranged in the first channel of the first central shaft. The end plate defines the amount of coolant or lubricant entering the interior. In other words, exactly as much coolant or lubricant enters the interior of the differential as is required to lubricate or cool the components or gears. This allows losses, particularly splashing losses or the like, to be avoided or at least reduced. The end plate can have perforations or holes that help regulate the pressure in the first channel.

[0026] The first central shaft preferably has at least one transverse bore. Coolant or lubricant can be branched off radially outwards via the transverse bore before it reaches the interior in order to cool or lubricate components of the planetary gear set. The transverse bore of the first central shaft can in particular be designed to supply the second and / or third bore on the axial section of the planet carrier with coolant or lubricant. In this case, the coolant or lubricant does not have to be guided via the interior but can be directed directly to the desired location, provided that the respective transverse bore does not have a negative effect on the load-bearing properties of the comparatively slender, first central shaft. Accordingly, it is also conceivable to provide more than one transverse bore on the first central shaft.

[0027] A drive train according to the invention for a vehicle comprises a transmission arrangement according to the preceding embodiments and a drive unit. The drive train can be used in a vehicle. The vehicle is preferably a motor vehicle, in particular an automobile (e.g., a passenger car weighing less than 3.5 t), a bus, or a truck (e.g., a bus and truck weighing more than 3.5 t). In particular, the vehicle is an electric vehicle or a hybrid vehicle. The vehicle comprises at least two axles, one of which forms an axle that can be driven by the drive train. The drive train according to the invention is operatively arranged on this drivable axle, the drive train transmitting drive power from the drive unit at least indirectly to the wheels of this axle via the transmission arrangement. It is also conceivable to provide such a drive train for each axle.The drivetrain is preferably installed in a front-transverse design, so that the drive shaft of the drive unit and the input shaft of the transmission assembly are aligned essentially transversely to the vehicle's longitudinal direction. Alternatively, the drivetrain can be arranged diagonally to the vehicle's longitudinal and transverse axes, with the output shafts connected via corresponding joints to the wheels of the respective axle, which are arranged transversely to the vehicle's longitudinal axis.

[0028] In this context, the term "at least indirectly" means that two components are (operatively) connected to each other via at least one additional component arranged between the two components, or are directly and thus immediately connected to each other. Thus, additional components can be arranged between shafts or gears that are operatively connected to the shaft or gear.

[0029] A “drive-effective connection” of components means that these components are either directly connected to one another, for example in a rotationally fixed manner, or can be indirectly connected to one another via at least one further component, for example via at least one further shaft and / or at least one further gear.

[0030] The above definitions as well as explanations of technical effects, advantages and advantageous embodiments of the transmission arrangement according to the invention also apply mutatis mutandis to the drive train according to the invention, and vice versa.

[0031] In the following, an embodiment of the invention is explained in more detail with reference to the schematic drawings, wherein identical or similar components are provided with the same reference numerals. Fig. 1 is a highly schematic plan view of a vehicle with a drive train according to the invention and a transmission arrangement according to the invention according to a preferred embodiment, and Fig. 2 a highly simplified longitudinal sectional view of the only partially shown gear arrangement according to the invention according to Fig. 1.

[0032] According to Fig. 1 shows a vehicle F with two vehicle axles 29a, 29b, wherein a drive train 2 according to the invention is arranged on the first vehicle axle 29a in a drive-effective manner, i.e., for driving wheels 30 of the vehicle F. The vehicle F here is an electric vehicle, wherein the drive of the vehicle F is purely electrical. The first vehicle axle 29a can be either the front axle or the rear axle of the vehicle F and forms a driven vehicle axle of the vehicle F. In the present case, the first vehicle axle 29a is the non-steerable rear axle of the vehicle F.

[0033] The drive train 2 comprises Fig. 1 in combination with Fig. 2 shows a transmission arrangement 1, wherein a drive power of a drive unit 3 designed as an electric machine is transmitted via the transmission arrangement 1 to a differential 9, which divides the drive power between a first central shaft 10 and a second central shaft 11. The central shafts 10, 11 serve as output or driven shafts of the drive train 2 and are each connected to the aforementioned wheel 30 of the first vehicle axle 29a.

[0034] The transmission arrangement 1 comprises a planetary gear set 4 with a sun gear 17 which is rotatably driven via an input shaft 31 and acts as the drive part of the planetary gear set 4, a planet carrier 5 which acts as the output part of the planetary gear set 4, and a ring gear (not shown here) which is fixed, i.e., non-rotatably arranged. The input shaft 31 is connected to the drive unit 3 according to Fig.1 are connected to the planet carrier 5. Bolts 6 are attached to each of which a first bearing element 7 is arranged for rotatably supporting an associated planetary gear 8.

[0035] The differential 9, which is drivingly connected to the planetary carrier 5, has a differential housing 33 fixedly connected to the planetary carrier 5 via screws 32, to which an axle 36 is attached, with differential bevel gears 26, 34 arranged rotatably thereon and spaced from one another. The differential bevel gears 26, 34 mesh with two axle gears 25, 35, each of which is non-rotatably connected to one of the coaxially arranged central shafts 10, 11 via a spline 24. Drive power converted by the planetary gear set 4 is distributed between the two central shafts 10, 11 via the planetary carrier 5 and the aforementioned components of the differential 9.

[0036] The first central shaft 10 has a central first channel 12, through which coolant or lubricant is conveyed into an interior 13 of the differential 9 by a coolant and / or lubricant supply (not shown here), for example, designed as a pump. A perforated end plate 27 is arranged in the first channel 12, whereby a defined amount of coolant or lubricant per unit of time reaches the interior 13 of the differential 9.

[0037] The planet carrier 5 has an axial section 16 on which a sun gear 17 of the planetary gear set 4 is rotatably mounted and radially supported via a second bearing element 18 designed as a needle bearing. The sun gear 17 is further axially supported on the planet carrier 5 via a third bearing element 21 designed as a cylindrical roller bearing, which serves as an axial bearing, and is rotatably mounted thereon.

[0038] The coolant or lubricant is conveyed outward from the interior 13 in order to cool or lubricate the bearing elements and gearing of the transmission arrangement 1, in particular the planetary gear set 4. The flow direction of the coolant or lubricant is illustrated by the dotted arrows P. Several bores 14, 19, 20 extending at least partially radially are provided on the planetary carrier 5. In this example, the first bore 14 is designed obliquely to the longitudinal axis L of the planetary gear set 4 or to the rotational axis of the central shafts 10, 11 in order to guide a portion of the coolant or lubricant from the interior 13 of the differential 9 into a second channel 15 of the pin 6. In the present case, the first bore 14 opens directly into the second channel 15 in order to supply the first bearing element 7 with coolant or lubricant.

[0039] Furthermore, a second and third bore 19, 20 are formed on the axial section 16 of the planet carrier 5, which extend essentially radially. The second bearing element 18 is supplied with coolant or lubricant via the second bore 19. The third bearing element 21 and a first gearing 22 between the sun gear 17 and the planet gear 8 are supplied with coolant or lubricant via the third bore 20. Furthermore, the first central shaft 10 has at least one transverse bore 28 to supply the second bearing element 18 with coolant or lubricant. The first central shaft 10 can have further transverse bores for supplying coolant or lubricant to components of the transmission arrangement 1, which, however, will not be discussed in detail here.

[0040] A portion of the coolant or lubricant passes from the interior 13 of the differential 9 via a second toothing 23 between the first differential bevel gear 26 of the differential 9 and the first axle gear 25 meshing therewith to the first bore 14. Another portion of the coolant or lubricant passes from the interior 13 of the differential 9 via the spline 24 between the first central shaft 10 and the first axle gear 25 meshing therewith to the second and third bores 19, 20. Reference symbol 1 Gear arrangement 2 Drivetrain 3 Drive unit 4 planetary gear set 5 Planet carrier of the planetary gear set 6 bolts 7 First bearing element 8 Planetary gear 9 Differential 10 First central shaft 11 Second central shaft 12 First Channel 13 Interior of the differential 14 First drilling 15 Second channel 16 Axial section of the planet carrier 17 Sun gear of the planetary gear set 18 Second bearing element 19 Second borehole 20 Third hole 21 Third bearing element 22 First gearing 23 Second gearing 24 spline 25 First axle gear of the differential 26 First differential bevel gear 27 tailpipe 28 cross hole 29a First vehicle axle 29b Second vehicle axle 30 wheels 31 Input shaft 32 screw 33 Differential housing 34 Second differential bevel gear 35 Second axle gear of the differential 36 Axis F vehicle L Longitudinal axis P Arrow

Claims

[1] A transmission arrangement (1) for a drive train (2) of a vehicle, comprising a planetary gear set (4) with a planet carrier (5) on which at least one bolt (6) is arranged, wherein a first bearing element (7) for rotatably supporting a planet gear (8) is arranged on the bolt (6), wherein the transmission arrangement (1) further comprises a differential (9) drivingly connected to the planet carrier (5) and transmitting a drive power acting on the planet carrier (5) to a first central shaft (10) and a second central shaft (11) arranged coaxially thereto, wherein at least the first central shaft (10) has a central first channel (12) for supplying coolant and / or lubricant to an interior space (13) of the differential (9), wherein at least one first bore (14) extending radially at least in sections is formed on the planet carrier (5),to guide the coolant and / or lubricant from the interior (13) of the differential (9) into a second channel (15) of the bolt (6), wherein the planet carrier (5) has an axial section (16) on which a sun gear (17) of the planetary gear set (4) is rotatably mounted via at least one second bearing element (18), wherein at least one second bore (19) extending radially at least in sections is formed on the axial section (16) of the planet carrier (5) in order to supply the second bearing element (18) with coolant and / or lubricant. [2] Gear arrangement (1) according to claim 1, wherein at least one third bore (20) extending radially at least in sections is formed on the axial section (16) of the planet carrier (5) in order to supply a third bearing element (21) for supporting the sun gear (17) on the planet carrier (5) with coolant and / or lubricant. [3] Gear arrangement (1) according to claim 2, wherein the third bore (20) is further configured to supply a first toothing (22) between the sun gear (17) and the planet gear (8) of the planetary gear set (4) with coolant and / or lubricant. [4] Gear arrangement (1) according to one of claims 1 to 3, wherein the second bore (19) and / or the third bore (20) is fluidically connected to the interior (13) of the differential (9) via a spline (24) between the first central shaft (10) and a first axle gear (25) of the differential (9) connected thereto. [5] Gear arrangement (1) according to one of the preceding claims, wherein the first bore (14) of the planet carrier (5) is fluidically connected to the interior (13) of the differential (9) via a second toothing (23) between a first differential bevel gear (26) of the differential (9) and a first axle gear (25) of the differential (9) meshing therewith. [6] Gear arrangement (1) according to one of the preceding claims, wherein a perforated end plate (27) is arranged in the first channel (12) of the first central shaft (10). [7] Gear arrangement (1) according to one of the preceding claims, wherein the first central shaft (10) has at least one transverse bore (28). [8] Drive train (2) for a vehicle, comprising a drive unit (3) and a transmission arrangement (1) according to one of the preceding claims.

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