Gear unit for an electric drive

Abstract

Gear unit (10) for an electric drive, with an output (12), with an electric machine (16) having a rotor (20), with a first planetary gear set (24) comprising a first sun gear (26) rotationally fixed to the rotor (20), a first planet carrier (28) and a first ring gear (30), with a second planetary gear set (35) comprising a second sun gear (36), a second planet carrier (38) and a second ring gear (40), and with at least two switching elements (44, 46) for switching at least two gears of the gear unit (10), wherein the second ring gear (40) is rotationally fixed to the output (12), wherein the first ring gear (30) is rotationally fixed to the second sun gear (36) and the first planet carrier (28) is rotationally fixed to a housing (32) of the gear unit by means of a first of the switching elements (44, 46). (10) is connectable, characterized by,that the second planet carrier (38) is fixed to a housing (32) of the transmission device (10) and the first planet carrier (24) can be coupled to the second ring gear (40) by means of a second of the switching elements (44, 46).

Description

[0001] The invention relates to a transmission device for an electric drive according to the preamble of claim 1.

[0002] Such a transmission device for an electric vehicle is, for example, already known from DE 10 2015 203 194 A1. The transmission device comprises at least one electric machine having a rotor. In particular, the electric machine has, for example, a stator, wherein the rotor is rotatable about an axis of rotation relative to the stator. The transmission device further comprises a first planetary gear set, which includes a first sun gear fixed to the rotor, a first planet carrier, and a first ring gear. A second planetary gear set is also provided, which includes a second sun gear, a second planet carrier, and a second ring gear. The transmission device further comprises at least two switching elements for switching at least two gears of the transmission device.The transmission device, also referred to as a transmission, has an output through which torques for driving the electric vehicle can be supplied, for example, from the transmission device, particularly from the second planetary gear set. The output is thus, for example, assigned to a terminal through which the torques for driving the vehicle can be derived from the transmission device or from the second planetary gear set and thus supplied by the transmission device or from the second planetary gear set.

[0003] The object of the present invention is to further develop a transmission device for an electric drive in such a way that a particularly compact and low-loss design of the transmission device can be achieved.

[0004] This problem is solved by a transmission device with the features of claim 1. Advantageous embodiments with expedient further developments of the invention are specified in the remaining claims.

[0005] To further develop a transmission device of the type specified in the preamble of claim 1 in such a way as to achieve a particularly low-loss and compact design of the transmission device, the invention provides that the second ring gear is rotationally fixed to the output. Thus, for example, the second ring gear belongs to the output of the transmission device, in particular to the second planetary gear set, so that torques for driving, for example, an electric vehicle designed as a passenger car, can be derived from the transmission device or the second planetary gear set and provided by the transmission device or the second planetary gear set.

[0006] It was found that the permanently fixed coupling of the second ring gear to the output allows for a particularly advantageous overall gear ratio of the transmission device, thereby minimizing losses and the space required for the transmission device. Specifically, the overall space requirement, weight, number of parts, and cost of a powertrain for propelling the electric vehicle can be significantly reduced because the fixed coupling of the second ring gear to the output allows for such an advantageous overall gear ratio that a further transmission device, also known as a final drive, is neither required nor necessary. Furthermore, losses, especially internal losses, of the transmission device can be kept particularly low, as relative speeds in open switching elements can be minimized.Furthermore, relative speeds in the planetary gear sets can be kept particularly low. Additionally, the speed of the electric machine, especially its rotor, can be kept particularly low at high speeds because the transmission device is designed with multiple gears. This multiple gearing means that the transmission device includes gears, also known as transmission gears, which can be shifted, i.e., engaged or activated.

[0007] In an advantageous embodiment of the invention, the first ring gear is, in particular permanently, or continuously, coupled to the second ring gear in a rotationally fixed manner, whereby a particularly advantageous overall transmission ratio can be achieved.

[0008] Another embodiment is characterized in that the second planet carrier is fixed to a housing of the transmission device. The planet gear sets are arranged at least partially, and in particular at least predominantly or completely, within the housing, wherein, for example, at least the first sun gear is rotatable about an axis of rotation relative to the housing. The first sun gear can be driven by the electric machine, in particular by its rotor, and is thus rotatable about the axis of rotation. Because the second planet carrier is fixed to the housing of the transmission device in the aforementioned embodiment, it is non-rotatably connected to the housing, preventing it from rotating relative to the housing. This allows for a particularly advantageous gear ratio, minimizing losses and the required installation space.

[0009] To achieve particularly advantageous switching and transmission characteristics of the transmission device, a further embodiment of the invention provides that the first planet carrier can be coupled to the housing of the transmission device in a rotationally fixed manner by means of a first switching element. The first switching element is, for example, adjustable, and in particular movable, between at least one coupled state or at least one coupled position and at least one uncoupled state or at least one end-coupling position. In the coupled position, the first planet carrier is coupled to the housing in a rotationally fixed manner via the first switching element, so that the first planet carrier cannot rotate relative to the housing. In the uncoupled position, however, the first switching element releases the first planet carrier, so that the planet carrier can rotate relative to the housing, in particular about the aforementioned axis of rotation.Thus, in the decoupling state of the first switching element, the first planet carrier is not coupled to the housing via the first switching element.

[0010] In a further embodiment of the invention, the first planet carrier can be locked to the second ring gear by means of a second of the switching elements. Locking the first planet carrier to the second ring gear via the second switching element means that, in its locked state, the first planet carrier is non-rotatably connected to the second ring gear, causing the first planet carrier and the second ring gear to rotate together, i.e., as a single unit, particularly around the aforementioned axis of rotation, and thus to rotate around the axis of rotation relative to the housing.

[0011] The second switching element, for example, is adjustable, and in particular movable, between at least one coupled state or coupled position and at least one decoupling state or decoupling position. In the coupled position of the second switching element, the first planet carrier is locked to the second ring gear via the second switching element and thus rotationally fixed. In the decoupling position of the second switching element, however, the second switching element releases the first planet carrier, or the locking of the first planet carrier to the second ring gear, so that the second ring gear is then no longer rotationally fixed to the first planet carrier via the second switching element.

[0012] To achieve particularly low-loss operation, the respective switching element is preferably designed as a positive-locking switching element. This means, for example, that the first planet carrier is positively and rotationally locked to the housing via the first switching element in its coupled state. Alternatively or additionally, the first planet carrier is positively locked to the second ring gear via the second switching element in its coupled state. In particular, the respective switching element is designed, for example, as a claw or claw coupling. Furthermore, it is conceivable that at least one of the switching elements is designed as a friction switching element, and in particular as a multi-plate switching element or multi-plate coupling, while the other switching element is designed, for example, as a positive-locking switching element or claw coupling.This means that only one lamellar switching element is open when the lamellar switching element or both switching elements are in the respective decoupling state.

[0013] To achieve a particularly advantageous drive system for the electric vehicle with a favorable gear ratio in a space-saving manner, a further embodiment of the invention provides that the second ring gear has external teeth which mesh directly with a gear of an axle drive, in particular a spur gear or ring gear. Thus, the axle drive can be driven via the gear and the external teeth of the second ring gear in a particularly space-saving, low-loss, and compact manner.

[0014] The transmission device according to the invention further enables a particularly advantageous stacking of the planetary gear sets. Within the stacking arrangement, the planetary gear sets are not arranged one after the other in the axial direction and thus in respective planes spaced apart from each other in the axial direction of the transmission device, but preferably both planetary gear sets are arranged in a common plane, with the second sun gear being formed by an external toothing of the first ring gear. This allows the installation space requirement to be kept particularly low.

[0015] To achieve a particularly effective and efficient drive system for the electric vehicle, it has proven advantageous to use a planetary differential driven by the planetary gear sets. Alternatively, the transmission system may feature a bevel gear differential driven by the planetary gear sets.

[0016] The planetary differential and the bevel gear differential are collectively referred to as differentials or differential gears, or are designed as differentials or differential gears, whereby such a differential gear allows, for example, when the electric vehicle is cornering, a speed compensation between the inner wheel and the outer wheel without causing excessive tension in the drivetrain.

[0017] Finally, to achieve a particularly advantageous transmission ratio, it has proven beneficial to provide an additional locking switching element for locking the first planetary gear set. Locking a planetary gear set, or the first planetary gear set, can be understood in particular as follows: The respective sun gear is a first transmission element of the respective planetary gear set, the respective ring gear is a second transmission element, and the respective planet carrier is a respective third transmission element of the respective planetary gear set. Furthermore, the respective planetary gear set has, for example, at least one or more planet gears that mesh with the respective ring gear and the respective sun gear of the respective planetary gear set.To lock the planetary gear set, two of the three respective gear elements are connected to each other in a rotationally fixed manner, i.e., locked together, so that the rotationally fixed gear elements rotate as a block around a common axis of rotation, in particular around the aforementioned axis of rotation.

[0018] By locking the planetary gear set, it is in a locked state in which the interlocked gear elements rotate together around the aforementioned axis of rotation as a single unit. If the planetary gear set is not locked, it is in an unlocked state in which, for example, the gear elements that were locked together in the locked state can rotate relative to each other around the axis of rotation.

[0019] In particular, the interlocking of the first planetary gear set by means of the interlocking switching element provides that the first planet carrier is interlocked with the first sun gear and thus with the rotor of the electric machine. Alternatively, the interlocking of the first planetary gear set can be achieved, for example, by interlocking the first planet carrier with the first ring gear by means of the interlocking switching element.

[0020] Further advantages, features, and details of the invention will become apparent from the following description of preferred embodiments and from the drawings. The features and combinations of features mentioned above in the description, as well as those mentioned below in the figure description and / or shown in the figures alone, can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the invention.

[0021] The drawing shows in: Fig. 1 a schematic representation of a transmission device according to the invention in a first embodiment, with an output, with a first planetary gear set and with a second planetary gear set, wherein a ring gear of the second planetary gear set is rotationally fixed to the output; Fig. 2 a schematic representation of a transmission device according to a second embodiment; Fig. 3 a schematic representation of the transmission device according to a third embodiment; Fig. 4 a schematic representation of a transmission device according to a fourth embodiment; Fig. 5 a schematic representation of the transmission device according to a fifth embodiment; Fig. 6 a schematic representation of the transmission device according to a sixth embodiment; Fig. 7 a schematic representation of a gear device according to a seventh embodiment; and Fig. 8 a schematic representation of the transmission device according to an eighth embodiment.

[0022] In the figures, identical or functionally equivalent elements are provided with the same reference numerals.

[0023] Fig. Figure 1 shows a schematic representation of a first embodiment of a device consisting entirely of 10 designated transmission device for an electric drive, in particular for an electric vehicle, which is designed, for example, as a passenger car and is powered by means of the transmission device 10 is driveable. The gearbox device 10 includes at least one electrical machine 16 , which has a stator 18 and a rotor 20 exhibits. The rotor 20 is about an axis of rotation relative to the stator 18 rotatable and thereby from the stator 18 can be driven. This allows the electric machine to be driven. 16 over its rotor 20 Provide torque. The rotor, for example, includes a [missing word] about the axis of rotation relative to the stator. 18 rotatable shaft 22 , via which the electric machine 16 can provide the aforementioned torques.

[0024] The transmission device 10 features a first planetary gear set 24 on, which is also known as the first planetary gear set. The first planetary gear set 24 has a rotationally fixed design with the rotor 20 coupled first sun wheel 26 on, which, for example, is rotationally fixed to the shaft 22 connected, in particular integrally with the shaft 22 trained.

[0025] This allows the electric machine to 16 via the rotor 20 , especially via the wave 22 , provided torques via the first sun gear 26 into the first planetary gear set 24 be initiated. Furthermore, the first planetary gear set exhibits 24 a first planetary carrier 28 and a first ring gear 30 on, which, for example, is relative to a point in the aforementioned axis of rotation. Fig. 1 particularly schematically represented housing32 the transmission device 10 It is rotatable. Thus, the rotor 20 , especially the wave 22 , and the first sun wheel 26 around the axis of rotation relative to the housing 32 rotatable. For example, the electric machine 16 at least partially, in particular at least predominantly or completely, in the housing 32 recorded. The first planetary gear set 24 at least one planetary gear has 34 on, which with the first sun wheel 26 and with the first ring gear 30 combs. In particular, the first planetary gear set exhibits 24 several first planetary gears, which are connected to the ring gear 30 and the sun wheel 26 comb. The following and previous explanations regarding the planetary gear 34 can easily be applied to the other planetary gears of the first planetary gear set as well. 24 are transferred and vice versa.

[0026] Furthermore, the transmission device 10 a second planetary gear set 35 on, which is also referred to as the second planetary gear set. The second planetary gear set 35 has a second sun wheel 36 , a second planetary carrier 38 and a second ring gear 40 on. Furthermore, the second planetary gear set includes 35 for example, at least one second planetary gear 42 , which is connected to the second sun wheel 36 and with the second ring gear 40 combs. In particular, the second planetary gear set includes 35 several second planetary gears, which are connected to the sun gear 36 and the ring gear 40 comb. The following and previous explanations regarding the second planetary gear are relevant here. 42 without further ado also on the other planetary gears of the planetary gear set 35 transferable and vice versa.

[0027] Furthermore, the transmission device 10a downforce 12 on, via which of the transmission device 10 , especially from the second planetary gear set 35 , in the Fig. 1 by an arrow 14 The illustrated torques, particularly for powering the electric vehicle, can be provided. In particular, the second planetary gear set can be used via the output shaft. 12 the arrow 14 Illustrated torques provide for powering the electric vehicle. The drive 12 is, for example, an output or belongs to an output of the transmission device 10 , in particular the second planetary gear set, so that the aforementioned torques from the gear unit can be transmitted via the output 10 or from the second planetary gear set 35 diverted and thus from the transmission device 10 or from the second planetary gear set 35 can be removed.

[0028] Furthermore, the transmission device 10 two switching elements 44 and 46 for shifting at least two gears of the transmission device 10 The gears are also referred to as transmission gears and each has a gear ratio, whereby, for example, the gear ratio of the first gear differs from the gear ratio of the second gear. In other words, the gears have different gear ratios. Preferably, the second gear is deactivated or disengaged when the first gear is engaged or activated. Furthermore, it is preferably provided that the first gear is deactivated or disengaged when the second gear is engaged or activated. It is also conceivable that both gears are engaged, so that the transmission device 10 for example, when idling.

[0029] In order to achieve a particularly low-loss and compact design of the gearbox device 10 , in particular one designed to drive the electric vehicle and the transmission device 10 The second hollow gear is necessary to realize the comprehensive drivetrain of the electric vehicle as a whole. 40 , in particular permanently or continuously, rotationally fixed to the output 12 coupled. The outdrive 12 For example, a shaft in the form of an output shaft 47 on, via which the transmission device 10 or the second planetary gear set 35 the arrow 14 The illustrated torques can be provided. The output shaft is involved. 47 , in particular permanently or continuously, rotationally fixed to the second ring gear 40 coupled or connected, whereby it may be provided that the output shaft 47 one piece with the ring gear 40is trained.

[0030] In particular, it is intended that the respective switching element 44 or 46 , in particular by means of a respective actuator (not shown in the figure), is actively switchable, adjustable, or movable between at least two different states, especially positions. Furthermore, in the case of the gear device, it is 10 provided that the first hollow gear 30 , in particular permanently or continuously, rotationally fixed to the second sun wheel 36 is coupled or connected. The ring gear 30 and the sun wheel 36 They therefore rotate together, or as a block, around the axis of rotation and thus rotate together around the axis of rotation relative to the housing. 32 , especially when the planetary gear sets 24 and 35 , for example by means of the electric machine 16, are driven. To drive the planetary gear sets 24 and 35 The electric machine 16 - as previously described - via the rotor 20 Torque ready.

[0031] Furthermore, it is the case with the transmission device 10 provided that the second planetary carrier 38 , especially permanently or constantly, on the casing 32 is determined. This makes the planetary carrier 38 against a rotation relative to the housing 32 secured, so that the planetary carrier 38 not relative to the case 32 can turn.

[0032] Furthermore, the first planetary carrier 28 by means of the switching element 44 rotationally fixed to the housing 32 connectable. The switching element 44 is thereby, in particular by means of the switching element 44the previously mentioned actuator is adjustable between the states, with one of the states being that of the switching element. 44 one coupling state and the other state of the switching element 44 a decoupling state of the switching element 44 is. In the coupling state of the switching element 44 is the planet carrier 28 by means of the switching element 44 on the case 32 fixed and thus resistant to rotation relative to the housing 32 secured. However, in the decoupling state, the switching element 44 the planetary carrier 28 for a rotation relative to the housing 32 about the axis of rotation freely, so that the planet carrier then 28 around the axis of rotation relative to the housing 32 can rotate and not via the switching element 44 on the case 32 is fixed. The switching element is... 44for example designed as a brake, whereby the switching element 44 in particular as a friction switching element and, for example, as a multi-plate clutch or multi-plate switching element.

[0033] The switching element 46 is, however, trained to carry the first planetary carrier 28 with the second hollow gear 40 to lock it in place and thus prevent it from rotating with the output 12 , especially with the output shaft 47 , to connect. For example, the switching element 46 , in particular by means of the aforementioned switching element 46 assigned actuator, adjustable, switchable or movable between states, wherein one of the states of the switching element 46 one coupling state and the other state of the switching element 46 a decoupling state of the switching element 46 is. In the coupling state of the switching element 46is the planet carrier 28 by means of the switching element 46 with the hollow gear 40 locked and therefore rotationally fixed to the ring gear 40 connected. However, in the decoupling state, the switching element 46 the planetary carrier 28 free, so that the planetary carrier 28 not via the switching element 46 with the hollow gear 40 is blocked. As a result, for example, the planetary carrier can 28 relative to the hollow gear 40 and relative to the case 32 rotate around the axis of rotation. Is the planet carrier 28 however via the switching element 46 with the hollow gear 40 Blocked, that's how the planetary carrier runs 28 and the ring gear 40 together, or as a block, around the aforementioned axis of rotation and rotate together around the axis of rotation relative to the housing 32 .

[0034] It is specifically intended that the switching element 44 is in its coupled state, while the switching element 46 is in its decoupling state. Furthermore, it is preferably provided that the switching element 46 is in its coupled state, while the switching element 44 is in its decoupling state.

[0035] The aforementioned first gear is engaged or activated, for example, when the shift element... 44 in its coupling state and the switching element 46 is in its decoupling state. Second gear, for example, is engaged or activated when the shift element is in its disengaged state. 46 in its coupling state and the switching element 44 is in its decoupling state.

[0036] The switching element 46is designed, for example, as a positive-locking switching element and preferably as a coupling or positive-locking coupling such as a claw coupling, so that in the coupling state of the switching element 46 the planetary carrier 28 by means of the switching element 46 positively locking with the ring gear 40 is blocked. Is the switching element 44 for example, the planet carrier is designed as a friction switching element. 28 by means of the switching element 44 frictionally locked to the housing 32 determined. By, for example, only one of the switching elements 44 and 46 If the friction switching element, in particular a friction plate switching element, is designed, only one friction switching element or friction plate switching element runs open when the friction element or both switching elements are in contact with the ground. 44 and 46are open, meaning they are in their decoupling state. This allows internal losses to be kept particularly low. In the Fig. In the first embodiment shown in 1, the planetary gear sets are 24 and 35 in the axial direction of the gear device 10 or in relation to a torque flow from the electric machine 16 to the downforce 12 between the output and the electric machine 16 arranged.

[0037] The planetary gear set follows. 35 with regard to the aforementioned torque flow to the planetary gear set 24 , so that the planetary gear set 35 in the axial direction behind the planetary gear set 24 is arranged. In other words, the planetary gear sets are arranged in respective planes spaced apart from each other in the axial direction. Furthermore, in the first embodiment, the planetary gear set is provided that 24in the axial direction of the gear device 10 between the electric machine 16 and the planetary gear set 35 is arranged.

[0038] Fig. Figure 2 shows a second embodiment of the transmission device 10 The second embodiment differs from the first embodiment in particular in that, in the second embodiment, the planetary gear set 35 in the axial direction of the gear device 10 between the electric machine 16 and the planetary gear set 24 is arranged. With regard to the aforementioned torque flow from the electric machine. 16 to the downforce 12 However, the planetary gear set follows 35 on the planetary gear set 24 .

[0039] Fig. Figure 3 shows a third embodiment of the transmission device 10The third embodiment is based on the second embodiment. However, in the third embodiment, the transmission device includes 10 an axle gearbox 48 , which is also referred to as a differential or differential gear. The second ring gear has... 40 an external toothing 50 on, which is directly connected to a gear 52 of the axle drive 48 combs. This causes the axle drive to... 48 from the hollow gear 40 via the gear 52 can be driven, so that, for example, the drive is driven by or via the output shaft 12 available or provided torques and carried away by the second planetary gear set via the external gearing 50 onto the gear 52 transferred and thus into the axle gearbox 48 be initiated. The axle drive 48It is designed, for example, as a bevel gear differential and is assigned to an axle of the electric vehicle. The axle comprises at least two wheels spaced apart from each other in the transverse direction of the vehicle, which are connected to the axle drive. 48 and about this from the electric machine 16 are propellable.

[0040] The axle drive enables this 48 for example, a speed compensation between the wheels of the axle, so that the axle drive 48 This allows for a speed compensation between the wheels, especially when the electric vehicle is cornering. During such a cornering maneuver, the axle drive allows... 48 This means that the outer wheel has a higher rotational speed than the inner wheel. This is illustrated in... Fig. 3 arrows 54 Torques supplied by the axle drive 48 are transferred to the wheels, which are guided by the arrows. 54The illustrated torques can be driven. The gear 52 is designed, for example, as a spur gear or as a ring gear, whereby the structure and function of the axle drive 48 are already well known from the general state of the art and especially from series vehicle production.

[0041] Fig. Figure 4 shows a fourth embodiment in which the planetary gear sets are stacked. This means that both planetary gear sets 24 and 35 are arranged in a common plane that runs at least substantially perpendicular to the aforementioned axis of rotation. The second sun wheel is... 36 for example, through external teeth 56 of the first ring gear 30 educated.

[0042] Fig. Figure 5 shows a fifth embodiment of the transmission device 10 In the fifth embodiment, the transmission device comprises 10a planetary differential 58 a designed differential or differential gear, which - especially depending on the selected gear - is determined by the respective planetary gear set 24 or 35 is driveable. The planetary differential 58 includes a third sun wheel 60 , a third planetary carrier 62 and a third ring gear 64 , where, for example, the planetary carrier 62 and the sun wheel 60 respective outputs of the planetary differential 58 represent. Furthermore, the planetary differential includes 58 for example planetary gears 66 , which are attached to the planetary carrier 62 are rotatably mounted and connected to the sun wheel 60 and the ring gear 64 comb. The planetary gear sets are also present in the fifth embodiment. 24 and 35 stacked

[0043] Fig. Figure 6 shows a sixth embodiment of the transmission device 10 , which differs from the fifth embodiment in particular in that - especially instead of the planetary differential 58 - a bevel gear differential 68 is intended, for example, for the axle drive 48 corresponds. Fig. 7 shows a seventh embodiment in which, in addition to the switching elements, 44 and 46 intended interlocking switching element 70 is provided. The interlocking switching element 70 is designed, for example, as a locking coupling, wherein the locking switching element 70 preferably designed as a positive-locking switching element, in particular as a claw or claw coupling. By means of the interlocking switching element 70 is the first planetary gear set 24 lockable. Through this extension of the first planetary gear set. 24around the blocking switch element 70 An additional long gear can be generated, the translation of which, for example, matches the standard translation of the second planetary gear set. 35 This corresponds to the following. This seems particularly useful if the transmission device 10 Another translation stage follows. In the Fig. The seventh embodiment illustrated in section 7 is the first planetary gear set. 24 such by means of the interlocking switching element 70 It can be blocked by means of the blocking switch element. 70 the first planetary carrier 28 with the first hollow gear 30 It can be blocked.

[0044] In an embodiment not shown in the figure, it is conceivable that the interlocking switching element could be used. 70 instead of the planetary carrier 28 and the ring gear 30 the sun wheel 26 and the planetary carrier 28can be interlocked to form the first planetary gear set 24 to block. For example, the blocking switch element can be used for this purpose. 70 an actuator not shown in the figure is assigned, by means of which the blocking switching element 70 The device is switchable or adjustable, in particular movable, between at least one closed position and at least one open position. The closed position corresponds, for example, to the aforementioned coupling state of the switching element. 44 or 46 , where the open position corresponds, for example, to the aforementioned decoupling state of the switching element 44 or 46 This corresponds to the closed position of the interlocking switching element. 70 is the first planetary gear set 24 blocked in the manner described, so that, for example, the planetary carrier 28 with the hollow gear 30or with the sun wheel 26 together, or as a block, it rotates around the aforementioned axis of rotation. In particular, the planetary gear set is then 24 by means of the interlocking switching element 70 positively locked. However, in the open position, the planetary gear set is locked. 24 lifted, so that the planetary carrier 28 not with the hollow gear 30 or rather not with the sun wheel 26 is blocked.

[0045] Finally, it shows Fig. 8 an eighth embodiment. The eighth embodiment is based in particular on the one described in Fig. 3 third embodiment shown, wherein the eighth embodiment differs from the third embodiment in that in the eighth embodiment the additional switching elements 44 and 46 intended interlocking switching element 70is provided for. In the eighth embodiment, the interlocking switching element 70 trained to do so, in particular as described above, the planetary carrier 28 , in particular positive locking, with the sun wheel 26 to block.

[0046] Overall, the gearbox device allows for the following: 10 whose rotational speeds, especially relative speeds, are kept particularly low so that drag losses can be kept to a very low level. In particular, a coaxial or axis-parallel arrangement is conceivable, allowing for a particularly space-saving arrangement. In addition, an advantageous overall gear ratio can be achieved using the two planetary gear sets. 24 and 35 This can be achieved so that no further axle ratio is needed. The two gears can be selected using exactly two shift elements. 44 and 46This can be implemented in such a way that the number of parts, weight, and costs can be kept low. For example, the switching element 46 Since it is always an outgoing switching element, the switching element can 46 as a claw switching element, that is, as a form-locking switching element.

[0047] In particular, a load-shiftable 2-speed structure in a coaxial design with low power loss can be implemented for electric drives. The aforementioned gears can be considered driving gears, usable for both forward and reverse travel. Therefore, it is preferably provided that the first gear and / or the second gear is load-shiftable, meaning it can be shifted under load.

[0048] The first gear, designed as the first driving gear, is intended, for example, to enable towing a trailer. It is also intended, for instance, for creeping maneuvers to power the electric motor. 16 and to protect their power electronics from overheating. The second gear can be used as a second driving gear for normal operation. At least one of the switching elements 44 and 46 , in particular the switching element 46 It can be designed as a positive-locking switching element and thus, for example, as a jaw coupling with or without a synchronizing unit, in order to keep internal losses particularly low. If one of the switching elements 44 and 46 designed as a positive-locking switching element, in particular as a claw coupling, while the other of the switching elements 46 and 44 If it is designed as a friction switching element and thus, for example, as a lamellar switching element, then it runs in the transmission device10 Only one friction or lamellar switching element is open if the friction or lamellar switching element or both switching elements are closed. 44 and 46 is or are open, that is, is or are in its decoupling state.

[0049] By using a friction or lamellar switching element, in particular as the switching element 44 and / or the switching element 46 A load-capable shifting of the respective gear can be implemented. If, for example, no load shifting is required in second gear, or if load shifting in second gear is omitted, then both shift elements can be used. 44 and 46 These can be designed as positive-locking switching elements, and in particular as claw or claw couplings. Furthermore, particularly advantageous accessibility to the switching element can be achieved. 44 and 46This can be achieved. Furthermore, the speed difference in the respective switching element can be realized. 44 and 46 The dimensions can be kept small, allowing for simple synchronization, which is particularly advantageous for positive-locking switching elements. Finally, excellent stacking can be achieved, thus minimizing the required installation space. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 102015203194 A1

[0002]

Claims

[1] Gear unit (10) for an electric drive, with an output (12), with at least one electric machine (16) having a rotor (20), with a first planetary gear set (24) comprising a first sun gear (26) rotationally fixed to the rotor (20), a first planet carrier (28) and a first ring gear (30), with a second planetary gear set (35) comprising a second sun gear (36), a second planet carrier (38) and a second ring gear (40), and with at least two switching elements (44, 46) for switching at least two gears of the gear unit (10), characterized by , that the second ring gear (40) is coupled to the output (12) in a rotationally fixed manner. [2] Gear unit (10) according to claim 1, characterized by , that the first ring gear (30) is coupled to the second sun gear (36) in a rotationally fixed manner. [3] Gear unit (10) according to claim 1 or 2, characterized by, that the second planet carrier (38) is fixed to a housing (32) of the gear device (10). [4] Gear unit (10) according to any of the preceding claims, characterized by , that the first planet carrier (28) can be coupled in a rotationally fixed manner to a housing (32) of the transmission device (10) by means of one of the switching elements (44, 46). [5] Gear device (10) according to any of the preceding claims, characterized by , that the first planet carrier (24) can be locked to the second ring gear (40) by means of one of the switching elements (44, 46). [6] Gear device (10) according to any of the preceding claims, characterized by , that the second ring gear (40) has an external toothing (50) which meshes directly with a gear (52) of an axle drive (48). [7] Gear device (10) according to any of the preceding claims, characterized by, that both planet gear sets (24, 35) are arranged in a common plane, wherein the second sun gear (36) is formed by an external toothing (56) of the first ring gear (30). [8] Gear unit (10) according to claim 7, characterized by , that a planetary differential (58) is provided which can be driven by the planetary gear sets (24, 35). [9] Gear unit (10) according to claim 7, characterized by , that a bevel gear differential (68) is provided which can be driven by the planetary gear sets (24, 35). [10] Gear device (10) according to any of the preceding claims, characterized by an additional locking switching element (70) for locking the first planetary gear set (24).

Images