DE102016002567B4 - drive device, in particular for an electric vehicle - Google Patents

Abstract

Drive device with at least one drive unit, with at least one axle drive (11a-c) and with a multi-stage transmission (12a-c) arranged between the drive unit and the axle drive (11a-c), at least structurally intended for switching three forward gears (V1a-c, V2a-c, V3a-c), which has exactly three operatively interconnected planetary gear stages (P1a-c, P2a-c, P3a-c) with sun gears (P11a-c, P21a-c, P31a-c), ring gears (P13a-c, P23a-c, P33a-c) and planetary gear carriers (P12a-c, P22a-c, P32a-c), three switching units (S1a-c, S2a-c, S3a-c) each with two coupling elements (S11a-c, S12a-c, S21a-c, S22a-c, S31a-c, S32a-c), a transmission input element (13a-c) for the rotationally fixed connection of the drive unit and a transmission output element (14a-c) for the rotationally fixed connection of the axle drive (11a-c), wherein the transmission input element (13a-c) is permanently rotationally fixedly connected to the sun gear (P21a-c) of the second planetary gear stage (P2a-c), the transmission output element (14a-c) is permanently rotationally fixedly connected at least to the planetary gear carrier (P32a-c) of the third planetary gear stage (P3a-c) and the third switching unit (S3a-c) is provided to block the third planetary gear stage (P3a-c),
wherein the planetary gear carrier (P22a-c) of the second planetary gear stage (P2a-c) and the ring gear (P33a-c) of the third planetary gear stage (P3a-c) are permanently connected to one another in a rotationally fixed manner,
wherein the planetary gear carrier (P12a-c) of the first planetary gear stage (P1a-c) is fixed to the housing,
characterized in that
the sun gear (P11a-c) of the first planetary gear stage (P1a-c) and the ring gear (P23a-c) of the second planetary gear stage (P2a-c) are permanently connected to each other in a rotationally fixed manner,
the first switching unit (S1a-c) is intended to arrange the planetary gear carrier (P22a-c) of the second planetary gear stage (P2a-c) and the ring gear (P33a-c) of the third planetary gear stage (P3a-c) fixed to the housing,
the second switching unit (S2a-c) is intended to arrange the ring gear (P13a-c) of the first planetary gear stage (P1a-c) and the sun gear (P31a-c) of the third planetary gear stage (P3a-c) fixed to the housing.

Description

The invention relates to a drive device for a motor vehicle, in particular an electric vehicle or a motor vehicle with at least one purely electrically driven drive axle.

From the WO 2012/010340 A1 A drive device for an electric vehicle is already known, which has an electric motor, an axle drive and a multi-stage transmission arranged between the electric motor and the axle drive.
Furthermore, the DE 15 05 723 B and the US 2003 / 0 162 624 A1 Multi-stage transmission with three interconnected planetary gear stages.

The generic DE 10 2013 226 473 A1 shows a transmission for an electric or hybrid vehicle, in which three planetary gear stages are linked together in such a way that a planetary gear carrier of a first planetary gear stage is fixed to the housing, a planetary gear carrier of a second planetary gear stage and a ring gear of a third planetary gear stage are permanently connected to one another in a rotationally fixed manner.

The invention is based in particular on the object of providing a further developed drive device for an electric vehicle. According to the invention, this is achieved by the features of claim 1. Further embodiments emerge from the subclaims.

The starting point is a drive device, in particular for an electric vehicle, with at least one electric motor, with at least one axle drive and with a multi-stage transmission arranged between the electric motor and the axle drive, at least structurally intended for switching three forward gears, which has exactly three operatively interconnected planetary gear stages with sun gears, ring gears and planetary gear carriers, three switching units, each with two coupling elements that can be connected to one another in a rotationally fixed manner, a transmission input element for the rotationally fixed connection of the electric motor and a transmission output element for the rotationally fixed connection of the axle drive, wherein the transmission input element is permanently rotationally fixedly connected to the sun gear of the second planetary gear stage, the transmission output element is permanently rotationally fixedly connected at least to the planetary gear carrier of the third planetary gear stage and the third switching unit is intended to block the third planetary gear stage.

Furthermore, it is provided in a known manner that the planetary gear carrier of the second planetary gear stage and the ring gear of the third planetary gear stage are permanently connected to one another in a rotationally fixed manner, wherein the planetary gear carrier of the first planetary gear stage is arranged fixed to the housing.

According to the invention, it is provided that the sun gear of the first planetary gear stage and the ring gear of the second planetary gear stage are permanently connected to one another in a rotationally fixed manner, wherein the first switching unit is provided for arranging the planetary gear carrier of the second planetary gear stage and the ring gear of the third planetary gear stage fixed to the housing, and wherein the second switching unit is provided for arranging the ring gear of the first planetary gear stage and the sun gear of the third planetary gear stage fixed to the housing.

Such a design makes it possible to provide a compact drive device for an electric vehicle that enables an advantageous connection of the electric motor to the axle drive. The multi-stage transmission can provide different forward gears, through which a drive torque delivered by the electric motor can be advantageously implemented. The ability to switch reverse gears can be dispensed with by providing the electric motor for reversing the direction of rotation. Component loads can be at least partially reduced in the proposed multi-stage transmission through its basic structure, which in particular makes lightweight construction easier. The differently geared forward gears mean that the electric motor can be operated with a high degree of efficiency even at high vehicle speeds. At low speeds, a torque from the electric motor can be advantageously implemented. Gear ratios of the forward gears and/or the axle drive can be at least partially adapted to a design of the electric vehicle. A flexible drive device can be provided.

In this context, a "drive device with at least one electric motor, with at least one axle drive and a multi-stage transmission arranged between the electric motor and the axle drive" is to be understood in particular as a drive device that only has electric motors for generating a drive torque. In particular, this is to be understood as a drive device that is independent of an internal combustion engine. In this context, a "multi-stage transmission" is to be understood in particular as a transmission arranged between the electric motor and the axle drive for switching the forward gears with different ratios. A "planetary gear stage" is to be understood in particular as a gear stage that is connected by a Tooth engagement between a sun gear and a planetary gear guided by a planetary gear carrier and/or tooth engagement between a planetary gear guided by a planetary gear carrier and a ring gear is defined. In principle, the planetary gear stages can be designed at least partially as one piece. In particular, it is conceivable that two of the planetary gear stages have a common ring gear and separate sun gears or a common sun gear and separate ring gears. An “axle drive” is to be understood in particular as an operative connection between the transmission output element of the multi-stage transmission and at least one drive wheel of the motor vehicle. The axle drive can be provided for a permanent, rotationally fixed connection between the transmission output element and the drive wheel. Alternatively, the axle drive can also have a differential gear which is provided to connect two drive wheels in parallel to the transmission output element.

The planetary gear stages are referred to below as “first planetary gear stage”, “second planetary gear stage” and “third planetary gear stage”. The designations “first”, “second” and “third” planetary gear stage are intended in particular to specify an axial arrangement, whereby an axial sequence of the planetary gear stages can deviate from the numbering. In principle, a modified arrangement of the planetary gear stages and/or a stacked arrangement in which the planetary gear stages are at least partially nested radially within one another is conceivable. Various kinematically equivalent transmission structures can be implemented in particular by spatially rearranging the switching units, by changing the arrangement of transmission elements and/or by swapping the sun gears, planetary gears and/or ring gears. “Kinematically equivalent transmission structures” are to be understood as transmission structures which have the same number of switching units and identical switching patterns for switching the forward gears and the reverse gears.

A “switching unit” is to be understood in particular as a unit with exactly two coupling elements that can be rotated relative to one another and that are provided for a rotationally fixed connection to one another. A switching unit can be designed either as a clutch or a brake. A switching unit that is designed as a “clutch” is to be understood in particular as a switching unit that is arranged in a power flow between two of the planetary gear stages and that is intended to connect its two rotatably arranged coupling elements, which can be rotated independently of one another in an open state, to one another in a rotationally fixed manner in a closed state. A switching unit that is designed as a “brake” is to be understood in particular as a switching unit that is operatively arranged between one of the planetary gear stages and a transmission housing and that is intended to connect its rotatable coupling element, which can be rotated independently of the transmission housing in an open state, to its coupling element that is rotationally fixedly connected to the transmission housing in a closed state. The term “rotatably connected” is to be understood in particular as meaning a connection in which a power flow is transmitted over a complete revolution on average with an unchanged torque, an unchanged direction of rotation and/or an unchanged speed.

In this context, a switching unit should not be understood to mean a clutch that is connected upstream or downstream of a gear set formed by the planetary gear stages. A “clutch connected upstream of the gear set” should be understood to mean a clutch that is arranged in at least one gear in a power flow between the electric motor and the transmission input element, such as a separating clutch or a starting clutch. A “clutch connected downstream of the gear set” should be understood to mean a clutch that is arranged in at least one gear in a power flow between the transmission output element and an axle drive, such as an all-wheel drive clutch. In principle, the shiftability of the multi-stage transmission can be increased by a clutch unit that is connected upstream or downstream of the gear set. A "gearbox input element" is to be understood in particular as a gear box element that is at least structurally intended for the rotationally fixed connection of a rotor of the electric motor. A "gearbox output element" is to be understood in particular as a gear box element that is at least structurally intended for the rotationally fixed connection of an axle drive. A "gearbox element" is to be understood in particular as a design that is intended for the permanent rotationally fixed connection between the sun gears, planet gear carriers, ring gears and/or coupling elements.

The term “at least structurally” is to be understood in particular as meaning that a corresponding design is provided structurally, but in a possible embodiment, a functional use of the structural design can be dispensed with. The term “structurally provided for switching a transmission gear” is to be understood in this context in particular as meaning that by means of the switching units and planetary gear stages, a corresponding transmission gear can in principle be formed mechanically, regardless of whether the gear shifting is dispensed with within the scope of a shifting strategy or not. For example, in one embodiment, the shifting units can be designed to shift more forward transmission gears than it may be sensible to shift within the scope of an operating strategy for the multi-stage transmission.

The term “blocking a planetary gear stage” is to be understood in particular as meaning that the sun gear, the planet gear carrier and the ring gear of an individual planetary gear stage are connected to one another in a rotationally fixed manner, whereby in such an operating state they always have the same speed and the same direction of rotation. A “switching unit for blocking a planetary gear stage” is to be understood as a single switching unit with two coupling elements, each of which is permanently connected to the sun gear, the planet gear carrier or the ring gear of the corresponding planetary gear stage in a rotationally fixed manner, whereby the corresponding planetary gear stage can be blocked by closing this one switching unit. In principle, the individual clutch unit for blocking the planetary gear stage can also be replaced by two clutch units connected in series.

Preferably, some of the switching units are designed to be positively locked. This means that drag loss can be kept low, which can advantageously reduce power loss within the multi-stage transmission. In particular, it is possible to design two of the three switching units to be positively locked. A "positively locked switching unit" is to be understood in particular as a switching unit which has teeth and/or claws for connecting its coupling elements or for connecting its coupling element, which engage with one another in a positively locked manner to produce a rotationally fixed connection, with a power flow being transmitted in a fully closed state at least mainly by a positive locking. The switching units can basically be designed to be frictionally locked or positively locked. A “frictionally engaged switching unit” is to be understood in particular as a switching unit which has at least two friction partners for connecting its coupling elements or for connecting its coupling element, which frictionally engage one another to produce a rotationally fixed connection, wherein a power flow is transmitted in a fully closed state at least mainly by friction. A frictionally engaged clutch unit is preferably designed as a multi-disk clutch unit and a frictionally engaged brake unit is preferably designed as a multi-disk brake unit. A positively engaged clutch unit is preferably designed as a claw clutch unit and a positively engaged brake unit is preferably designed as a claw brake unit. A positively engaged switching unit can advantageously be switched via a sliding sleeve. The positively engaged switching units are preferably designed without frictionally engaged synchronization, but can in principle also have frictionally engaged synchronization.

The multi-stage transmission preferably comprises actuators for the automated switching of the switching units. In principle, however, it is also possible to design at least some of the switching units to switch at least partially independently. An independently switching clutch unit or brake unit is preferably designed as a freewheel. In addition, a design of the planetary gear stages with single planetary gear sets or double planetary gear sets can also deviate from the exemplary embodiments shown. In a kinematically equivalent manner, it is possible, for example, to replace a single planetary gear set with a double planetary gear set, whereby in particular a stationary gear ratio of the planetary gear stage must be adjusted for a kinematically identical mode of operation. In particular, when designed using a double planetary gear set, a connection of a sun gear and a planetary gear carrier, a ring gear and a planetary gear carrier or a sun gear and a ring gear can also be exchanged, whereby in particular a stationary gear ratio of the planetary gear stage must be adjusted for a kinematically identical mode of operation.

The terms "axial" and "radial" are referred to in particular in the following to the main axis of rotation of the multi-stage transmission, so that the term "axial" refers in particular to a direction that runs parallel or coaxially to the main axis of rotation. Furthermore, the term "radial" refers in particular to a direction that runs perpendicular to the main axis of rotation. A "transmission input-side arrangement" is to be understood in particular to mean that the said component is arranged on a side of the further component that faces the transmission input element and/or the electric motor. A "transmission output-side arrangement" is to be understood in particular to mean that the said component is arranged on a side of the further component that faces away from the transmission input element and/or the electric motor, even if the further component is axially the transmission output element, for example because the transmission output element is arranged between two planetary gear stages.

Further advantages emerge from the following description of the figures. The figures show several embodiments of the invention. To distinguish the embodiments, the reference symbols in the following description of the figures are supplemented by the letters a to c. With regard to components with the same designation, in particular with regard to components with the same reference symbols, reference should generally be made to the description and/or the drawings of the first embodiment with the letter a. The descriptions of the other embodiments are essentially limited to the differences between the embodiments. The figures, the description of the figures and the claims contain numerous features in combination. The person skilled in the art will expediently also consider the features individually and combine them into useful further combinations.

• 1 ein Kraftfahrzeug mit einer Antriebsvorrichtung, die einen Elektromotor und ein Mehrstufengetriebe aufweist,
• 2 ein Getriebeschema des Mehrstufengetriebes,
• 3 ein Schaltschema für das Mehrstufengetriebe aus 2,
• 4 ein Getriebeschema mit Planetenradstufen in einer geänderten Anordnung, und
• 5 ein Getriebeschema mit Planetenradstufen, die teilweise gestapelt sind.

The following show:

• 1 a motor vehicle with a drive device comprising an electric motor and a multi-speed transmission,
• 2 a transmission diagram of the multi-stage transmission,
• 3 a shift diagram for the multi-speed transmission 2 ,
• 4 a transmission scheme with planetary gear stages in a modified arrangement, and
• 5 a transmission scheme with planetary gear stages that are partially stacked.

1 shows a motor vehicle with a drive device. The drive device is intended for an electric motor drive of the motor vehicle. The motor vehicle can be designed as a purely electric vehicle. The drive device is only intended for the electric motor drive. In principle, it is conceivable that the drive device is combined with a second drive device for an internal combustion engine drive. For example, the proposed drive device, which is intended for the electric motor drive, can act on a first drive axle of the motor vehicle, while the drive device, which is intended for the internal combustion engine drive, acts on a second drive axle of the motor vehicle. If the proposed drive device is combined with an internal combustion engine drive device, it is also conceivable that the motor vehicle has an additional summing and/or selection gear that is connected downstream of the two drive devices and that is intended to connect both drive devices to a single drive axle.

The drive device comprises an electric motor 10a, an axle drive 11a and a multi-stage transmission 12a arranged between the electric motor 10a and the axle drive 11a (cf. 2 ). The electric motor 10a can be a permanently excited synchronous machine or a permanently excited asynchronous machine. The multi-stage transmission 12a is at least structurally intended for switching three differently geared forward gears V1a, V2a, V3a. The multi-stage transmission 12a has exactly three planetary gear stages P1a, P2a, P3a. The multi-stage transmission 12a has a main axis of rotation, to which the first planetary gear stage P1a, the second planetary gear stage P2a and the third planetary gear stage P3a are arranged coaxially. The multi-stage transmission 12a is structurally intended for switching exactly three differently geared forward gears V1a, V2a, V3a. The number of forward gears V1a, V2a, V3a actually used can be limited depending on an operating strategy, for example electronically by an appropriately programmed control and regulating unit.

In principle, a drive device is also conceivable in which the multi-stage transmission 12a is combined with a drive unit in the form of an internal combustion engine. The internal combustion engine then either replaces the electric motor 12a as the drive unit or the internal combustion engine is used together with the electric motor 12a as the drive unit.

The multi-stage transmission 12a has exactly three shifting units S1a, S2a, S3a, which are intended for shifting the forward gears V1a, V2a, V3a. The multi-stage transmission 12a has a transmission housing 15a, which accommodates the planetary gear stages P1a, P2a, P3a and the shifting units S1a, S2a, S3a. The shifting units S1a, S2a, S3a are operatively arranged within a gear set formed by the planetary gear stages P1a, P2a, P3a, i.e. the shifting units S1a, S2a, S3a are intended to produce different operative connections between the planetary gear stages P1a, P2a, P3a and/or between the planetary gear stages P1a, P2a, P3a and the transmission housing 15a.

The 3 The switching diagram shown shows how the forward gears V1a, V2a, V3a are switched by closing the switching units S1a, S2a, S3a. The forward gears V1a, V2a, V3a are each switched by closing one of the three switching units S1a, S2a, S3a switched. Each of the switching units S1a, S2a, S3a is assigned to exactly one of the forward gears V1a, V2a, V3a. A power shift between two of the forward gears V1a, V2a, V3a is always possible in particular when at most one of the switching units S1a, S2a, S3a is closed and/or at most one of the switching units S1a, S2a, S3a is opened in a switching process, ie when a power flow is transferred from one of the switching units S1a, S2a, S3a to another of the switching units S1a, S2a, S3a or when a switching state of just one of the switching units S1a, S2a, S3a is changed. The three forward gears V1a, V2a, V3a can basically be fully power shifted between one another.

The multi-stage transmission 12a connects the electric motor 10a to the axle drive 11a of the motor vehicle. The multi-stage transmission 12a can be used to change a transmission ratio between the electric motor 10a and the axle drive 11a. The multi-stage transmission 12a has a transmission input element 13a, which is intended to introduce the drive torque delivered by the electric motor 10a into the multi-stage transmission 12a. The electric motor 10a comprises a rotor, which in the embodiment shown is permanently connected to the transmission input element 13a in a rotationally fixed manner. The transmission input element 13a can be designed in different ways, for example as a shaft or as a flange.

The multi-stage transmission 12a also has a transmission output element 14a, which is intended to output a drive torque from the multi-stage transmission 12a. In the exemplary embodiment shown, the axle drive 11a has a differential gear, the input of which is permanently connected in a rotationally fixed manner to the transmission output element 14a. The axle drive 11a is intended to distribute the drive torque provided by the electric motor 10a to the two drive wheels of the drive axle. Alternatively, it is also conceivable that the transmission output element 14a is permanently connected in a rotationally fixed manner to an axle shaft and/or one of the drive wheels. For example, the motor vehicle can have two of the drive devices, each of which acts directly on a drive wheel of the motor vehicle. In addition, at least one further module can be arranged between the transmission output element 14a and the axle drive 11a, such as an all-wheel drive module that distributes the drive torque to two different drive axles. The transmission output element 14a can be designed in different ways, such as as a shaft, as a spur gear or as a pinion.

The transmission input element 13a and the transmission output element 14a are arranged coaxially to the main axis of rotation. The transmission input element 13a is arranged on a side of the multi-stage transmission 12a facing the electric motor 10a. For the transmission output element 14a, fundamentally different arrangements are conceivable in the axial direction. In the multi-stage transmission 12a shown, the planetary gear stages P1a, P2a, P3a are arranged between the transmission input element 13a and the transmission output element 14a. In principle, a rearrangement of the planetary gear stages P1a, P2a, P3a is possible in which the transmission output element 14a is arranged between two of the planetary gear stages P1a, P2a, P3a. The planetary gear stages P1a, P2a, P3a are arranged one behind the other in the axial direction. To redesign the multi-stage transmission 12a, it is possible to change the sequence of the planetary gear stages P1a, P2a, P3a along the main axis of rotation. The multi-stage transmission 12a has three levels in which the planetary gear stages P1a, P2a, P3a are arranged. A numbering of the levels corresponds to a sequence of levels, which is referred to the transmission input element 13a below. The first level has a smaller distance to the electric motor 10a than the third level.

The first planetary gear stage P1a is arranged along the main axis of rotation in the first plane. The first planetary gear stage P1a has a single planetary gear set and comprises a sun gear P11a, a ring gear P13a and a planetary gear carrier P12a. The planetary gear carrier P12a guides planetary gears P14a on a circular path. The planetary gears P14a mesh with the sun gear P11a and with the ring gear P13a. The planetary gears P14a are rotatably mounted on the planetary gear carrier P12a.

The second planetary gear stage P2a is arranged along the main axis of rotation in the second plane. The second planetary gear stage P2a is arranged along the main axis of rotation on a side of the first planetary gear stage P1a facing away from the transmission input element 13a. The second planetary gear stage P2a has a single planetary gear set and comprises a sun gear P21a, a ring gear P23a and a planetary gear carrier P22a. The planetary gear carrier P22a guides planetary gears P24a on a circular path. The planetary gears P24a mesh with the sun gear P21a and with the ring gear P23a. The planetary gears P24a are rotatably mounted on the planetary gear carrier P22a.

The third planetary gear stage P3a is arranged along the main axis of rotation in the third plane. The third planetary gear stage P3a is arranged along the main axis of rotation on a The third planetary gear stage P3a has a single planetary gear set and comprises a sun gear P31a, a ring gear P33a and a planetary gear carrier P32a. The planetary gear carrier P32a guides planetary gears P34a on a circular path. The planetary gears P34a mesh with the sun gear P31a and with the ring gear P33a. The planetary gears P34a are rotatably mounted on the planetary gear carrier P32a.

Two of the switching units S1a, S2a, S3a are designed as brakes. The switching units S1a, S2a designed as brakes each have a rotatably mounted coupling element S11a, S21a and a coupling element S12a, S22a arranged fixedly to the housing. The switching units S1a, S2a are each provided to connect their rotatably mounted coupling element S11a, S21a to the transmission housing 15a in a rotationally fixed manner. Each of the rotatably mounted coupling elements S11a, S21a of the switching units S1a, S2a is permanently connected in a rotationally fixed manner to at least one of the sun gears P11a, P21a, P31a, one of the planet gear carriers P12a, P22a, P32a and/or one of the ring gears P13a, P23a, P33a. The coupling elements S12a, S22a of the switching units S1a, S2a, which are fixed to the housing, are permanently connected in a rotationally fixed manner to the transmission housing 15a.

The remaining switching unit S3a is designed as a clutch. The switching unit S3a designed as a clutch has a first rotatably mounted coupling element S31a and a second rotatably mounted coupling element S32a. The switching unit S3a is provided to connect its two coupling elements S31a, S32a to one another in a rotationally fixed manner. Each of the coupling elements S31a, S32a of the switching unit S3a is permanently connected in a rotationally fixed manner to at least one of the sun gears P11a, P21a, P31a, one of the planet gear carriers P12a, P22a, P32a and/or one of the ring gears P13a, P23a, P33a.

To connect the planetary gear stages P1a, P2a, P3a to one another and to the coupling elements S11a, S12a, S21a, S22a, S31a, S32a, the multi-stage transmission 12a comprises a plurality of transmission elements 16a, 17a, 18a, 19a. The four transmission elements 16a, 17a, 18a, 19a are provided to support and/or transmit torques and/or rotational movements within the gear set formed by the planetary gear stages P1a, P2a, P3a. Each of the transmission elements 16a, 17a, 18a, 19a permanently connects at least two of the sun gears P11a, P21a, P31a, planet gear carriers P12a, P22a, P32a, ring gears P13a, P23a, P33a and/or coupling elements S11a, S12a, S21a, S22a, S31a, S32a to one another in a rotationally fixed manner or permanently supports at least one of the sun gears P11a, P21a, P31a, planet gear carriers P12a, P22a, P32a and/or ring gears P13a, P23a, P33a against the transmission housing 15a.

The transmission input element 13a forms a transmission input shaft that permanently connects the transmission input element 13a and the sun gear P21a of the second planetary gear stage P2a to one another in a rotationally fixed manner. The transmission input element 13a is connected to the sun gear P21a on the input side.

The transmission output element 14a forms a transmission output shaft that permanently connects the transmission output element 14a and the planetary gear carrier P32a of the third planetary gear stage P3a in a rotationally fixed manner. The transmission output shaft formed by the transmission output element 14a passes through the sun gear P31a of the third planetary gear stage P3a and is guided radially outwards for the connection of the planetary gear carrier P32a between the second planetary gear stage P2a and the third planetary gear stage P3a.

The transmission element 16a forms an intermediate shaft that permanently connects the first coupling element S11a of the first switching unit S1a, the planetary gear carrier P22a of the second planetary gear stage P2a and the ring gear P33a of the third planetary gear stage P3a to one another in a rotationally fixed manner. The intermediate shaft formed by the transmission element 16a passes through the planetary gear stage P1a. Between the first planetary gear stage P1a and the second planetary gear stage P2a as well as between the second planetary gear stage P2a and the third planetary gear stage P3a, the transmission element 16a is guided radially outwards. The intermediate shaft formed by the transmission element 16a limits the gear set on the transmission input side.

The transmission element 17a forms an intermediate shaft that permanently connects the sun gear P31a of the third planetary gear stage P3a, the second coupling element S32a of the third switching unit S3a, the first coupling element S21a of the second switching unit S2a and the ring gear P13a of the first planetary gear stage P1a to one another in a rotationally fixed manner. The intermediate shaft formed by the transmission element 17a encloses the planetary gear stages P2a, P3a. It limits the gear set on the output side.

The gear element 18a forms an intermediate shaft that permanently connects the sun gear P11a of the first planetary gear stage P1a and the ring gear P23a of the second planetary gear stage P2a in a rotationally fixed manner. The gear element 18a is guided radially outwards between the planetary gear stages P1a, P2a.

The transmission element 19a forms a connection that permanently connects the planetary gear carrier P22a of the second planetary gear stage P2a and the transmission housing 15a in a rotationally fixed manner. The planetary gear carrier P22a is thus arranged fixed to the housing.

The first switching unit S1a is arranged in the axial direction on the transmission input side of the first planetary gear stage P1a. The second switching unit S2a is arranged axially at the level of the first planetary gear stage P1a. The third switching unit S3a is arranged axially on the transmission output side of the third planetary gear stage P3a. In principle, a different spatial arrangement of the switching units S1a, S2a, S3a is also possible.

The first switching unit S1a is intended to arrange the planetary gear carrier P22a of the second planetary gear stage P2a and the ring gear P33a of the third planetary gear stage P3a so that they are fixed to the housing. The second switching unit S2a is intended to arrange the ring gear P13a of the first planetary gear stage P1a and the sun gear P31a of the third planetary gear stage P3a so that they are fixed to the housing. The third switching unit S3a is intended to connect the sun gear P31a of the third planetary gear stage P3a and the planetary gear carrier P32a of the third planetary gear stage P3a so that they cannot rotate with one another. If the third switching unit S3a is closed, the sun gear P31a and the planetary gear carrier P32a of the third planetary gear stage P3a are connected to one another so that they cannot rotate with one another. The third planetary gear stage P3a is thus blocked. Alternatively, the third switching unit S3a can also be provided to permanently connect the sun gear P31a and the ring gear P33a of the third planetary gear stage P3a or the planetary gear carrier P32a and the ring gear P33a of the third planetary gear stage P3a in a rotationally fixed manner.

All switching units S1a, S2a, S3a are externally designed, i.e. the actuating means for the switching units S1a, S2a, S3a can be supplied without the need for operating medium lines to pass through a pivoting component. None of the switching units S1a, S2a, S3a are internally designed, i.e. they require operating medium to pass through a pivoting component. All switching units S1a, S2a, S3a are hydraulically operated.

In the described embodiment, the axle drive 11a has the differential gear, the outputs of which are arranged coaxially to the main rotation axis of the multi-stage transmission 12a (cf. 1 ). In the described embodiment, the axle drive 11a also comprises two axle shafts for driving the drive wheels of a drive axle. In an advantageous embodiment, the axle drive 11a has a main axis of rotation which is arranged coaxially to the main axis of rotation of the multi-stage transmission 12a. Preferably, one of the axle shafts passes through at least the transmission input element 13a and the electric motor 10a. In particular, it is possible to at least partially integrate the axle drive 11a into the multi-stage transmission 12a. Nesting of the multi-stage transmission 12a and the axle drive 11a depends in particular on a position of the differential gear along the main axis of rotation of the multi-stage transmission 12a. If the differential gear is arranged between the transmission input element 13a and the transmission output element 14a, one of the axle shafts passes through the transmission input element 13a and the electric motor 10a, while the other axle shaft passes through the transmission output element 14a. If the differential gear of the axle drive 11a is arranged on the transmission output side, one of the axle shafts preferably passes through the transmission output element 14a, the transmission input element 13a and the electric motor 10a. Even in an embodiment in which the axle drive 11a is provided for a direct connection of only one drive wheel, it is conceivable to guide the transmission output element 14a in the form of an inner shaft through the transmission input element 13a and the electric motor 10a, whereby the electric motor 10a is arranged between the drive wheel and the multi-stage transmission 12a.

4 shows, as a second exemplary embodiment, a transmission diagram of a multi-stage transmission 12b for a drive device with an electric motor and an axle drive. The multi-stage transmission 12b is at least structurally intended for switching three forward transmission gears. The transmission diagram is structurally similar to that of the first exemplary embodiment.

The multi-stage transmission 12b comprises a transmission input element 13b for the rotationally fixed connection of the electric motor and a transmission output element 14b for the rotationally fixed connection of the axle drive. In addition, the multi-stage transmission 12b comprises a gear set with a first planetary gear stage P1b, a second planetary gear stage P2b and a third planetary gear stage P3b, each of which has a sun gear P11b, P21b, P31b, a ring gear P13b, P23b, P33b and a planetary gear carrier P12b, P22b, P32b, which guides planetary gears P14b, P24b, P34b in a circular path around the corresponding sun gear P11b, P21b, P31b. Furthermore, the multi-stage transmission 12b comprises three switching units S1b, S2b, S3b, each of which has two coupling elements S11b, S12b, S21b, S22b, S31b, S32b. For the transmission of power flows between the planetary gear stages P1b, P2b, P3b and/or for support against a transmission housing 15b, the multi-stage transmission 12b has a plurality of transmission elements 16b, 17b, 18b, 19b.

The multi-stage transmission 12b differs from that of the first embodiment in particular in the arrangement of the planetary gear stages P1b, P2b, P3b. The multi-stage transmission 12b has three levels in which the planetary gear stages P1b, P2b, P3b are arranged. The second planetary gear stage P2b is arranged in the first level. The first planetary gear stage P1b is arranged in the second level. The third planetary gear stage P3b is arranged in the third level. The first planetary gear stage P1b is arranged in the axial direction between the second planetary gear stage P2b and the third planetary gear stage P3b. The rearrangement of the planetary gear stages P1b, P2b results in a changed arrangement of the transmission elements 16b, 17b, 18b, 19b. The first switching unit S1b is arranged on the transmission input side of the second planetary gear stage P2b. The switching unit S2b is arranged axially at the level of the first planetary gear stage P1b.

5 shows, as a third exemplary embodiment, a transmission diagram of a multi-stage transmission 12c for a drive device with an electric motor and an axle drive. The multi-stage transmission 12c is at least structurally intended for switching three forward transmission gears. The transmission diagram is structurally similar to that of the first exemplary embodiment.

The multi-stage transmission 12c comprises a transmission input element 13c for the rotationally fixed connection of the electric motor and a transmission output element 14c for the rotationally fixed connection of the axle drive. In addition, the multi-stage transmission 12c comprises a gear set with a first planetary gear stage P1c, a second planetary gear stage P2c and a third planetary gear stage P3c, each of which has a sun gear P11c, P21c, P31c, a ring gear P13c, P23c, P33c and a planetary gear carrier P12c, P22c, P32c, which guides planetary gears P14c, P24c, P34c in a circular path around the corresponding sun gear P11c, P21c, P31c. The multi-stage transmission 12c further comprises three switching units S1c, S2c, S3c, each of which has two coupling elements S11c, S12c, S21c, S22c, S31c, S32c. To transmit power flows between the planetary gear stages P1c, P2c, P3c and/or to support against a transmission housing 15c, the multi-stage transmission 12c comprises a plurality of transmission elements 16c, 17c, 18c, 19c.

The multi-stage transmission 12c differs from that of the first embodiment in particular in an arrangement of the planetary gear stages P1c, P2c, P3c. In contrast to the first embodiment, the first planetary gear stage P1c and the third planetary gear stage P3c are arranged in a stacked manner. The multi-stage transmission 12c has two levels in which the planetary gear stages P1c, P2c, P3c are arranged. The second planetary gear stage P2c is arranged in the first level. The first planetary gear stage P1c and the third planetary gear stage P3c are arranged in the second level. The first planetary gear stage P1c is arranged radially within the third planetary gear stage P3c. The first switching unit S1c is arranged in the axial direction on the transmission input side of the second planetary gear stage P2c. The second switching unit S2c and the third switching unit S3c are arranged in the axial direction between the first plane in which the second planetary gear stage P2c is arranged and the second plane in which the planetary gear stages P1c, P3c are arranged.

It has been shown that the first switching unit S1a, S1b, S1c is particularly advantageously designed as a positive-locking switching unit. By designing the first switching unit S1a, S1b, S1c as a positive-locking switching unit, it is shown that the efficiency of the drive device can be increased, while still achieving an acceptable level of switching comfort overall. The efficiency of the drive device can also be further increased by designing the third switching unit S3a, S3b, S3c as a positive-locking switching unit. This can also achieve an acceptable level of switching comfort. After a detailed investigation of all the advantages and disadvantages, it has proven particularly advantageous to design both the first switching unit S1a, S1b, S1c and the third switching unit S3a, S3b, S3c as a positive-locking switching unit and to design the second switching unit S2a, S2b, S2c as a friction-locking switching unit.

List of reference symbols

10

electric motor

11

axle drive

12

multi-stage transmission

13

transmission input element

14

transmission output element

15

Gearbox housing

16

transmission element

17

transmission element

18

transmission element

19

transmission element

P1

planetary gear stage

P11

Sun gear

P12

planetary gear carrier

P13

ring gear

P14

Planetary gears

P2

planetary gear stage

P21

Sun gear

P22

planetary gear carrier

P23

ring gear

P24

Planetary gears

P3

planetary gear stage

P31

Sun gear

P32

planetary gear carrier

P33

ring gear

P34

Planetary gears

S1

switching unit

S11

coupling element

S12

coupling element

S2

switching unit

S21

coupling element

S22

coupling element

S3

switching unit

S31

coupling element

S32

coupling element

V1

forward gear

V2

forward gear

V3

forward gear

Claims (8)

Drive device with at least one drive unit, with at least one axle drive (11a-c) and with a multi-stage transmission (12a-c) arranged between the drive unit and the axle drive (11a-c), at least structurally intended for switching three forward gears (V1a-c, V2a-c, V3a-c), which has exactly three operatively interconnected planetary gear stages (P1a-c, P2a-c, P3a-c) with sun gears (P11a-c, P21a-c, P31a-c), ring gears (P13a-c, P23a-c, P33a-c) and planetary gear carriers (P12a-c, P22a-c, P32a-c), three switching units (S1a-c, S2a-c, S3a-c) each with two coupling elements (S11a-c, S12a-c, S21a-c, S22a-c, S31a-c, S32a-c), a transmission input element (13a-c) for the rotationally fixed connection of the drive unit and a transmission output element (14a-c) for the rotationally fixed connection of the axle drive (11a-c), wherein the transmission input element (13a-c) is permanently rotationally fixedly connected to the sun gear (P21a-c) of the second planetary gear stage (P2a-c), the transmission output element (14a-c) is permanently rotationally fixedly connected at least to the planet gear carrier (P32a-c) of the third planetary gear stage (P3a-c) and the third switching unit (S3a-c) is provided to block the third planetary gear stage (P3a-c), wherein the planet gear carrier (P22a-c) of the second planetary gear stage (P2a-c) and the ring gear (P33a-c) of the third planetary gear stage (P3a-c) are permanently connected to one another in a rotationally fixed manner, wherein the planetary gear carrier (P12a-c) of the first planetary gear stage (P1a-c) is arranged fixedly to the housing, characterized in that the sun gear (P11a-c) of the first planetary gear stage (P1a-c) and the ring gear (P23a-c) of the second planetary gear stage (P2a-c) are permanently connected to one another in a rotationally fixed manner, the first switching unit (S1a-c) is provided for arranging the planetary gear carrier (P22a-c) of the second planetary gear stage (P2a-c) and the ring gear (P33a-c) of the third planetary gear stage (P3a-c) fixedly to the housing, the second switching unit (S2a-c) is provided for arranging the ring gear (P13a-c) of the first planetary gear stage (P1a-c) and the sun gear (P31a-c) of the third planetary gear stage (P3a-c) must be arranged fixed to the housing. drive device according to Claim 1 , characterized in that the drive unit comprises an electric motor (10a). drive device according to Claim 1 or 2 , characterized in that the third switching unit (S3a-c) is designed as a positive-locking switching unit. Drive device according to one of the preceding claims, characterized in that the first switching unit (S1a-c) is designed as a positive-locking switching unit. Drive device according to one of the preceding claims, characterized in that the second switching unit (S2a-c) is designed as a frictional switching unit. Drive device according to one of the preceding claims, characterized in that the first planetary gear stage (P1c) and the third planetary gear stage (P3c) are arranged stacked. Drive device according to one of the preceding claims, characterized in that each of the switching units (S1a-c, S2a-c, S3a-c) is assigned to exactly one of the forward transmission gears (V1a, V2a, V3a). drive device according to claim 2 , characterized in that the axle drive (11a) has at least one axle shaft which transmission input element (13a), the transmission output element (14a) and/or the electric motor (10a).

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