Electric axle drive and motor vehicle powered by it

Abstract

Electric axle drive (10) for an at least partially electrically operated motor vehicle, comprising: - a first electric machine (12a) with a first rotor (14a), and a second electric machine (12b) with a second rotor (14b), comprising - a planetary differential gear (20) with an input shaft (16), a first output shaft (24a) and a second output shaft (24b), wherein the output shafts (24a,b) are designed to transfer torques from the planetary differential gear (20) in the direction of motor vehicle wheels (28a,b), wherein the first rotor (14a) can be coupled to the input shaft (16) in such a way that torques, originating from the first rotor (14a), can be introduced into the planetary differential gear (20) via the input shaft (16); - a first switching element (34a) by means of which the second rotor (14b) can be coupled to the first output shaft (24a) in such a way that torques originating from the second rotor (14b) can be introduced into the first output shaft (24a) bypassing the input shaft (16) and bypassing the second output shaft (24b); - a second switching element (34b), by means of which the second rotor (14b) can be coupled to the second output shaft (24b) in such a way that torques originating from the second rotor (14b) can be introduced into the second output shaft (24b) bypassing the input shaft (16) and bypassing the first output shaft (24a); characterized in that the first electric machine (12a) and the planetary differential gear (20) are arranged coaxially to one another and coaxially to a main axis of rotation (11), wherein - the first switching element (34a) and the second switching element (34b) are designed as friction switching elements, wherein a first disk pack (36a) of the first switching element (34a) and a second disk pack (36b) of the second switching element (34b) and a first actuating device (38a) of the first switching element (34a) and a second actuating device (38b) of the second switching element (34b) are arranged in a common clutch radial region (40) and axially next to one another, and wherein - a first inner support element (42a) of the first disk pack (36a) and a second inner support element (42b) of the second disk pack (36b) are connected to one another in a rotationally fixed manner and form a clutch input element (32), and a first outer support element (44a) of the first disk pack (36a) forms a first clutch output element (46a) and a second outer support element (44b) of the second disk pack (36b) forms a second clutch output element (46b).

Description

[0001] The invention relates to an electric axle drive for an at least partially electrically operated motor vehicle having a first electric machine with a first rotor, and a second electric machine with a second rotor, comprising a planetary differential gear with an input shaft, a first output shaft and a second output shaft, wherein the output shafts are designed to transfer torques from the differential gear in the direction of motor vehicle wheels, wherein the first rotor can be coupled to the input shaft in such a way that torques, originating from the first rotor, can be introduced via the input shaft into the planetary differential gear, further comprising a first switching element, by means of which the second rotor can be coupled to the first output shaft in such a way that torques,can be introduced into the first output shaft from the second rotor, bypassing the input shaft and the second output shaft, further comprising a second switching element by means of which the second rotor can be coupled to the second output shaft in such a way that torques can be introduced into the second output shaft from the second rotor, bypassing the input shaft and the first output shaft. The invention further relates to an electrically powered motor vehicle with such an axle drive.

[0002] Such an electric axle drive is known from DE 10 2021 006 124 B3.

[0003] WO 2022 / 238475 A1 discloses a drive system for a vehicle for variably distributing torque from a primary input and a secondary input between a left wheel and a right wheel of a vehicle, which system has an open differential and independently controllable first and second clutch packs.

[0004] The object of the invention is to make such an axle drive more compact.

[0005] The object is achieved according to claim 1 in that the first electric machine and the planetary differential gear are arranged coaxially to one another and coaxially to a main axis of rotation, wherein, with respect to the main axis of rotation, the first shifting element and the second shifting element are designed as friction shifting elements, wherein a first disk pack of the first shifting element and a second disk pack of the second shifting element and a first actuating device of the first shifting element and a second actuating device of the second shifting element are arranged in a common clutch radial region and axially next to one another, and wherein a first inner carrier element of the first disk pack and a second inner carrier element of the second disk pack are connected to one another in a rotationally fixed manner and form a clutch input element,and a first outer carrier element of the first disk pack forms a first clutch output element and a second outer carrier element of the second disk pack forms a second clutch output element.,

[0006] The combination of features according to the invention creates a usable installation space radially within the friction shift elements, which can be used for a ring gear spline and axial locking. This space can also accommodate axial and radial bearings for the second output shaft.

[0007] According to an advantageous embodiment of the invention, a planet carrier shaft of the planetary differential gear, which is connected in a rotationally fixed manner to the first output shaft, has a crank, and a sun gear shaft of the planetary differential gear, which is connected in a rotationally fixed manner to the second output shaft, has a step, wherein a radial bearing is arranged in a common first axial extension section and radially between the step and the crank, which radial bearing is integrated in a construction space radially inside and in an axial extension region of the clutch radial region.

[0008] This design enables an axially short electric drive unit. The second output shaft requires only a direct radial bearing, with the radial bearing of the sun gear shaft serving as the second radial bearing. The sun gear shaft is rotationally fixed to the second output shaft, meaning there is no need for a radial bearing between the second output shaft and the rotor of the second electric machine. This is energy efficient because the second electric machine is often stationary, which would result in high speed differences between the second output shaft and the second electric machine, and thus high bearing losses. The first electric machine is essentially always rotating when the vehicle is in operation, and the speed difference between the first output shaft and the first rotor of the first electric machine is virtually zero, so that bearing efficiency is less important.

[0009] According to an advantageous development of the invention, the planetary carrier shaft is shaped as a ring cup in a radially inner region and forms a cavity radially within the planetary differential gear, into which a spline of the input shaft with the first rotor extends at least partially. This has the advantage that the spline of the first input shaft can be designed to be axially long without requiring additional axial space.

[0010] According to an advantageous development of the invention, the input shaft is rotationally fixedly connected to the ring gear of the differential gear, with a parking lock gear arranged axially adjacent to the ring gear on the input shaft. Since the spline of the first input shaft can transmit the comparatively large torque from the vehicle's mass, it is possible to arrange the parking lock gear there, given the installation space.

[0011] According to an advantageous development of the invention, a first axial bearing is provided on an end face between the step of the sun gear shaft and the planet carrier shaft. This design enables a compact mounting of the sun gear shaft.

[0012] According to an advantageous development of the invention, a second axial bearing is provided on an end face between the step of the sun gear shaft and the second rotor.

[0013] According to an advantageous development of the invention, the clutch input element has an axial rotary oil transfer extension section, which has at least one first groove for rotary oil transfer of the actuating oil of the first shifting element, a second groove for rotary oil transfer of the actuating oil for the second shifting element, and a third groove for rotary oil transfer of cooling oil for the first and second shifting elements. The rotary oil transfer extension section is arranged at least partially radially within and in an axial extension region of the clutch radial region. This design contributes to an axially short construction.

[0014] According to an advantageous development of the invention, a housing section is provided which radially surrounds the rotary oil transfer extension section and is arranged radially between the clutch radial region and the clutch input element with the rotary oil transfer extension section and in an axial extension region of the clutch radial region. This design also contributes to an axially short construction.

[0015] The invention also encompasses an electrically powered motor vehicle with an electric axle drive according to one of the previously described embodiments. Due to the smaller axial extension of the drive device, such a vehicle can be constructed more compactly or smaller.

[0016] Further advantages, features, and details will become apparent from the following description, in which at least one embodiment is described in detail—possibly with reference to the drawings. Identical, similar, and / or functionally equivalent parts are provided with the same reference numerals.

[0017] They show: Fig. 1: a schematic partial representation of a drive system with the dual clutch and two electric drive motors; Fig. 2: an enlarged section of Fig. 1; Fig. 3: an axial section through the drive system according to Fig. 1.

[0018] In Fig. Figure 1 shows the upper half of a rotationally symmetrical drive system 10 (starting from a main rotational axis 11) comprising two electric motors 12a, 12b. The first electric motor 12a, shown on the left, comprises a first rotor 14a, which is coupled via an input shaft 16 to a ring gear 18 of a planetary differential gear 20. The first electric motor 12a and the planetary differential gear 20 are arranged coaxially to one another and coaxially to the main rotational axis 11.

[0019] A parking lock gear 22 for locking the drive system is coupled to the input shaft 16. The planetary differential gear 20 has two output shafts: a first output shaft 24a, which, starting from a double planetary carrier of the planetary differential gear 20, drives a first drive gear 28a via a first planetary gear set 26a to adapt to the high speed of the electric motor 12a.

[0020] The right in Fig. The second electric machine 12b shown in Figure 1 with a second rotor 14b is coupled via a claw clutch 30 and a clutch input element 32 to two switching elements 34a, 34b designed as friction clutches, which are alternately engaged. Fig. 1 right, first switching element 34a is connected via the double planet carrier of the planetary differential gear 20 to the first output shaft 24a, so that the second electric machine 12b in a first switching position with the first switching element 34a engaged and bypassing the input shaft 16 in addition to the first electric machine 12a Fig. 1 left drive wheel 28a.

[0021] The Fig. 1 and Fig. 2 left, second switching element 34b is connected to a second output shaft 24b, which is coupled to a second drive gear 28b via a second planetary gear set 26b. In a second switching position with the second switching element 34b engaged and the first switching element 34a disengaged, torques of the second electric machine 12b act on the Fig. 1 right, second drive wheel 28b.

[0022] In Fig. 3, the two switching elements 34a, 34b are shown in detail. These are designed as friction switching elements and each comprise a first and second plate pack 36a, 36b, which are engaged and disengaged by means of a first and a second actuating device 38a, 38b. The two actuating devices 38a, 38b are hydraulically designed and are actuated with hydraulic fluid against spring force. The two actuating devices 38a, 38b also comprise centrifugal oil chambers supplied with pressureless hydraulic fluid in order to compensate for pressure increases caused by centrifugal force and to make the control of the plate packs 36a, 36b more precise. The hydraulic fluid for cooling the plate packs 36a, 36b is diverted from the centrifugal oil chambers (not shown in detail).

[0023] The two actuating devices 38a, 38b are arranged axially next to each other or mirror-inverted opposite each other in a common clutch radial region 40 between the two disk packs 36a, 36b.

[0024] The two disk packs 36a, 36b each consist of two alternating disk sets, of which every other disk (inner disk) is fixed radially inward and every other disk (outer disk) is fixed radially outward in a rotationally fixed manner. The inner disks of the disk packs 36a, 36b are connected to one another in a rotationally fixed and axially fixed manner via a first and a second inner carrier element 42a, 42b and form the clutch input element 32. The respective outer disks of the disk packs 36a, 36b are coupled to one another in a rotationally fixed but axially displaceable manner via a first and a second outer carrier element 44a, 44b. The first outer carrier element 44a forms a cylindrical first clutch output element 46a, which is connected to the first output shaft 24a in a rotationally fixed manner via a planetary carrier shaft 48 of the planetary differential gear 20.The second outer carrier element 44b also forms a cylindrical second clutch output element 46b, which is rotationally fixedly connected to the second output shaft 24b. The planet carrier shaft 48 carries two rows of inner and outer planet gears 50, 52. The outer planet gears 52 mesh with a ring gear 54, and the inner planet gears 50 mesh with a sun gear shaft 56.

[0025] The planet carrier shaft 48 of the planetary differential gear 20, which is connected in a rotationally fixed manner to the first output shaft 24a, has an offset 58. In other words, the planet carrier shaft 48 initially extends radially inward in a disk-like manner and then has a bend (the offset) in order to extend radially inward again after a certain extent and there again in the axial opposite direction, forming an annular cup 64. The planet carrier shaft 48 is connected in a rotationally fixed manner to the first output shaft 24a by means of a spline 66. The annular cup 64 forms a cavity radially within the planetary differential gear 20, into which the spline 66 of the input shaft 16 with the first rotor 14a protrudes at least partially.

[0026] The sun gear shaft 56 initially has a contour adapted to the offset 58 of the planetary carrier shaft 48 and then transitions into a step 60, forming a cylindrical section. A radial bearing 62 is arranged in a common first axial extension section and radially between the step 60 and the offset 58. The radial bearing 62 is integrated in a space radially inside and in an axial extension region of the clutch radial region 40. The sun gear shaft 56 is connected in a rotationally fixed manner to the second output shaft 24b on the radial inside.

[0027] A first axial bearing 68 is provided on an end face between the step 60 of the sun gear shaft 56 and the planetary carrier shaft 48, via which the sun gear shaft 56 is supported on the planetary carrier shaft 48. The planetary carrier shaft 48 is supported on the input shaft 16 via a further axial bearing 70, which in turn is supported on the housing side via a left main bearing 72. A second axial bearing 74 is provided on an end face between the step 60 of the sun gear shaft 56 and the clutch input element or the second rotor 14b.

[0028] As in Fig.3, the clutch input element 32 has an axial rotary oil transfer extension section 76, which has at least a first groove 78a for a rotary oil transfer of the actuating oil of the first switching element 34a and a second groove 78b for a rotary oil transfer of the actuating oil for the second switching element 34b and a third groove 78c for a rotary oil transfer of cooling oil for the first and the second switching element 34a, 34b, wherein the rotary oil transfer extension section 76 is arranged at least partially radially inside and in an axial extension region of the clutch radial region 40.

[0029] Finally, a housing section 80 is provided which radially surrounds the rotary oil transfer extension section 76 and is arranged radially between the clutch radial region 40 and the clutch input element 32 with the rotary oil transfer extension section 76 and in an axial extension region of the clutch radial region 40, whereby the axial extension of the axle drive can be kept small.

[0030] Although the invention has been illustrated and explained in detail by means of preferred embodiments, the invention is not limited by the disclosed examples, and other variations may be derived therefrom by those skilled in the art without departing from the scope of the invention. It is therefore clear that a multitude of possible variations exist. It is also clear that the embodiments mentioned by way of example are truly only examples and should not be construed as limiting the scope, possible applications, or configuration of the invention in any way.Rather, the preceding description and the description of the figures enable the person skilled in the art to implement the exemplary embodiments in concrete terms, whereby the person skilled in the art, with knowledge of the disclosed inventive concept, can make various changes, for example with regard to the function or the arrangement of individual elements mentioned in an exemplary embodiment, without departing from the scope of protection defined by the claims and their legal equivalents, such as further explanations in the description.

Claims

[1] Electric axle drive (10) for an at least partially electrically operated motor vehicle, comprising: - a first electric machine (12a) with a first rotor (14a), and a second electric machine (12b) with a second rotor (14b), comprising - a planetary differential gear (20) with an input shaft (16), a first output shaft (24a) and a second output shaft (24b), wherein the output shafts (24a,b) are designed to transfer torques from the planetary differential gear (20) in the direction of motor vehicle wheels (28a,b), wherein the first rotor (14a) can be coupled to the input shaft (16) in such a way that torques, originating from the first rotor (14a), can be introduced into the planetary differential gear (20) via the input shaft (16); - a first switching element (34a) by means of which the second rotor (14b) can be coupled to the first output shaft (24a) in such a way that torques originating from the second rotor (14b) can be introduced into the first output shaft (24a) bypassing the input shaft (16) and bypassing the second output shaft (24b); - a second switching element (34b) by means of which the second rotor (14b) can be coupled to the second output shaft (24b) in such a way that torques originating from the second rotor (14b) can be introduced into the second output shaft (24b) bypassing the input shaft (16) and bypassing the first output shaft (24a); characterized by that the first electric machine (12a) and the planetary differential gear (20) are arranged coaxially to each other and coaxially to a main axis of rotation (11), wherein - the first switching element (34a) and the second switching element (34b) are designed as friction switching elements, wherein a first disk pack (36a) of the first switching element (34a) and a second disk pack (36b) of the second switching element (34b) and a first actuating device (38a) of the first switching element (34a) and a second actuating device (38b) of the second switching element (34b) are arranged in a common clutch radial region (40) and axially next to one another, and wherein - a first inner support element (42a) of the first disk pack (36a) and a second inner support element (42b) of the second disk pack (36b) are connected to one another in a rotationally fixed manner and form a clutch input element (32), and a first outer support element (44a) of the first disk pack (36a) forms a first clutch output element (46a) and a second outer support element (44b) of the second disk pack (36b) forms a second clutch output element (46b). [2] Electric axle drive (10) according to claim 1, characterized by in that a planet carrier shaft (48) of the planetary differential gear (20), which is connected in a rotationally fixed manner to the first output shaft (24a), has a crank (58) and a sun gear shaft (56) of the planetary differential gear (20), which is connected in a rotationally fixed manner to the second output shaft (24b), has a step (60), wherein a radial bearing (62) is arranged in a common first axial extension section and radially between the step (60) and the crank (58), which is integrated in a construction space radially inside and in an axial extension region of the clutch radial region (40). [3] Electric axle drive (10) according to claim 2, characterized bythat the planet carrier shaft (48) is shaped as an annular pot (64) in a radially inner region and forms a cavity radially inside the planetary differential gear (20), into which a spline (66) of the input shaft (16) with the first rotor (14a) projects at least partially. [4] Electric axle drive (10) according to one of claims 2 or 3, characterized by that the input shaft (16) is connected in a rotationally fixed manner to the ring gear (54) of the planetary differential gear (20), wherein a parking lock gear (22) is arranged on the input shaft (16) axially adjacent to the ring gear (54). [5] Electric axle drive (10) according to claim 2, characterized by that a first axial bearing (68) is provided on an end face between the step (60) of the sun gear shaft (56) and the planet carrier shaft (48). [6] Electric axle drive (10) according to claim 2, characterized bythat a second axial bearing (74) is provided on an end face between the step (60) of the sun gear shaft (56) and the second rotor (14b). [7] Electric axle drive (10) according to one of the preceding claims, characterized by in that the clutch input element (32) has an axial rotary oil transfer extension section (76) which has at least a first groove (78a) for a rotary oil transfer of the actuating oil of the first switching element (34a) and a second groove (78b) for a rotary oil transfer of the actuating oil for the second switching element (34b) and a third groove (78c) for a rotary oil transfer of cooling oil for the first and the second switching element (34a, 34b), wherein the rotary oil transfer extension section (76) is arranged at least partially radially inside and in an axial extension region of the clutch radial region (40). [8] Electric axle drive (10) according to one of the preceding claims, characterized bythat a housing section (80) is provided which radially surrounds the rotary oil transfer extension section (76) and is arranged radially between the clutch radial region (40) and the clutch input element (32) with the rotary oil transfer extension section (76) and in an axial extension region of the clutch radial region (40). [9] Electrically powered motor vehicle comprising an electric axle drive (10) according to one of the preceding claims.

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