Electric transmission for all-wheel drive

Abstract

Electric drive system that includes: an electric machine; a multi-speed gearbox rotatably connected to the electric machine, rotatably connected to two output shafts and includes: a differential gear, rotatably coupled to a mode planetary gear set and arranged coaxially thereto; and a mode coupling configured to switch between two operating modes.

Description

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to U.S. Provisional Application No. 63 / 515,754, entitled "ALL WHEEL DRIVE ELECTRIC TRANSMISSION," filed on July 26, 2023. The entire contents of the above-referenced application are hereby incorporated by reference for all purposes. TECHNICAL FIELD

[0002] This description refers generally to an electric transmission. BACKGROUND AND SUMMARY

[0003] Electric transmissions are used in a variety of vehicle platforms to meet the electrification needs of different vehicle sectors. These electric transmissions include traction motors and geared transmissions, which can be mounted in different configurations depending on the spatial constraints and intended use of the vehicle platform. In some cases, electric transmissions offer greater flexibility in terms of driveline architecture compared to electric axles.

[0004] At least some electric transmissions fail to meet the end-application targets for space efficiency, shift functionality, and power density. For example, some multi-speed transmissions utilize a multitude of parallel shafts and gears, which pose installation challenges. Furthermore, in earlier multi-speed transmissions, all gears are interconnected, but in certain modes, torque is transmitted only through a portion of the gears, while other gears remain unloaded. Therefore, the unloaded gears cause unavoidable bearing, meshing, and ventilation losses. Inventors have therefore recognized the desire to reduce installation space and increase the power density of electric transmissions.

[0005] The problems described above can be at least partially solved by an electric drive system. In one example, the electric drive system includes an electric machine and a multi-speed transmission rotatably coupled to the electric machine and rotatably coupled to two output shafts. The multi-speed transmission includes a front-rear differential rotatably arranged coaxially with a mode planetary gear set. The multi-speed transmission also includes a mode clutch that can be used to switch between two operating modes. In this way, the mode planetary gear set effectively achieves multiple gear ratio modes in a space-saving package and expands the system's speed-changing capabilities. Furthermore, the coaxial arrangement of the front-rear differential of the planetary gear set allows the axial length of the electric drive to be reduced if desired.

[0006] In one example, the mode planetary gear set may be a Ravigneaux gear set rotatably coupled to the front-rear differential. Furthermore, the mode clutch is configured to selectively lock a carrier or ring gear in the Ravigneaux gear set, lock a sun gear in the Ravigneaux gear set, and rotatably couple the carrier or ring gear to the sun gear in the Ravigneaux gear set. In this way, the Ravigneaux gear set's packaging efficiently achieves three gear ratio modes.

[0007] In another example, the mode clutch is configured to selectively switch the mode planetary gear set between a first mode in which the mode clutch locks a carrier or ring gear included in the mode planetary gear set, and a second mode in which the mode clutch rotatably connects the carrier to the ring gear. In this way, the mode planetary gear set achieves two-speed functionality in a compact package that is easier to integrate into a variety of vehicle designs.

[0008] It should be understood that the above summary is intended to introduce, in simplified form, a selection of concepts that are further explained in the detailed description. It is not intended to identify the most important or essential features of the claimed subject matter, the scope of which is clearly defined by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that address the disadvantages noted above or elsewhere in this disclosure. SHORT DESCRIPTION OF THE CHARACTERS Fig. 1 shows an electric vehicle with an electric drive that includes a transmission with a mode planetary gear set. Fig. 2-5 show different layouts of electric machines and gear drives in different electric drive architectures. Fig. 6-8 show various configurations of mode planetary gear sets in exemplary electric transmissions. Fig. Figure 9 shows an electric transmission with a planetary gear set providing the input for a mode planetary gear set. DETAILED DESCRIPTION

[0009] A multi-speed electric differential for the front and rear axles (e.g., a multi-speed electric differential for all-wheel drive) is described herein with a mode selection function that achieves increased compactness and power density. Furthermore, in one example, the electric transmission may have a north-south architecture. To achieve the desired space efficiency and power density, the electric transmission includes a transmission with a multi-speed mode planetary gear set and a front-rear axle differential in a coaxial housing. Specifically, the multi-speed gear set of the electric transmission includes a mode planetary gear set with a mode clutch for switching between gear modes.

[0010] In a first mode of the electric transmission, a relative speed exists between the elements of the mode planetary gear set. In the highest mode (e.g., a second mode in a two-speed transmission or a third mode in a three-speed transmission) of the electric transmission, the mode planetary gear set can be locked and rotate as a unit. The planetary gear set of the front-rear axle differential can also rotate as a unit and only differentiates when the vehicle has front-rear axle bias or is turning. In practice, the transmission may operate to a greater extent in the highest mode than in the lower modes (e.g., most of the time).In the highest operating mode, where there is little or no relative rotation of the components in the front-rear differential and little or no relative rotation of the components in the planetary gear set, gear mesh noise is reduced, component wear is reduced, component life is extended, friction losses are reduced, and ventilation losses are reduced, thereby increasing the overall efficiency of the transmission.

[0011] Additionally, in one example, the electric transmission may incorporate a compound planetary gear set of meshing planets. The electric transmission may passively transfer mechanical power from an electric machine or other suitable central power source to multiple front and rear differentials (e.g., a front differential and a rear differential). In this way, the need for multiple independent electric axles, multiple inverters, and associated support electronics may be eliminated, if desired. This reduces the size and complexity of the electric drive and increases the power density of the electric drive, enhancing customer appeal. The electric transmission may be front, mid, or rear mounted, providing significant design flexibility.In one example, the front or rear electric transmission outputs can also be actively braked to transfer more power to the opposing front or rear axle differentials. In another example, the electric transmissions described here can be used with solid axles, independent suspensions, or a combination of both axle types.

[0012] The electric transmission may, in one example, take the form of a two-speed transmission where the mode planetary gear set is configured as a compound planetary gear set of intermeshing planets with two sets of planetary gears meshing and circumferentially aligned in the same plane as a ring gear and a sun gear, or where the mode planetary gear set is configured as a single planetary gear set with one set of planetary gears meshing and circumferentially aligned in the same plane as a ring gear and a sun gear. In this way, the electric transmission achieves two-speed functionality with high power density in a compact manner, with the output of each mode rotating in the same direction as the input of the multi-speed planetary transmission.

[0013] In another example, the electric transmission may specifically take the form of a three-speed transmission in which the mode planetary gear set is a Ravigneaux planetary gear set. In a Ravigneaux planetary gear set, a compound planetary gear set with intermeshing planets and a simple planetary gear set share a common ring gear and a planetary gear (or a stepped planetary gear). Furthermore, in a Ravigneaux planetary gear set, two sun gears may mesh with each of the two planetary gear sets. In this way, the transmission modes are expanded in a compact and power-dense transmission architecture.

[0014] The above-mentioned electric transmission layouts allow a transmission disconnect clutch and / or a front-rear differential lock clutch to be easily and effectively incorporated into the transmission, enabling additional functionality that is difficult to accommodate on individual electric axles.

[0015] Fig. Figure 1 shows an example of an electric drive 100 with a transmission 102 that includes a mode planetary gear set 104. Therefore, the transmission can be referred to as an electric transmission. The electric drive 100 also includes a differential 105 (e.g., a front-rear differential). The front-rear differential 105 is designed as a differential compound planetary gear set with intermeshing planets, particularly in Fig. 1 and is therefore referred to as such. However, it is understood that other types of differentials may be used instead of the differential compound planetary gear set with intermeshing planets as in Fig. 1, and the other intermeshing planetary gear sets described herein. The front-to-rear differential may be, for example, a double sun gear differential configured as an open or limited-slip differential, a bevel gear differential, a reduction differential, or the like, as described in more detail herein. The mode planetary gear set 104 and the intermeshing planetary gear set 105 are discussed in more detail herein.

[0016] The electric drive 100 is included in an electric vehicle (EV) 103 in the illustrated example. It should be understood that the other electric drive systems described herein may also be included in a similar EV. The EV 103 may be a pure electric vehicle (e.g., a battery electric vehicle (BEV)) in one example or a hybrid electric vehicle (HEV) in another example. Thus, in some examples, vehicles utilizing the electric drive systems described herein may also have an internal combustion engine (e.g., a gasoline engine, a compression-ignition engine, combinations thereof, and the like).

[0017] In the HEV example, an engine and transmission may be used in conjunction with a transmission 102. The engine and transmission may form a parallel power path and be coupled to mechanical components 138 or 139 (discussed in more detail herein). Continuing with the HEV example, in a motor-drive mode, the engine and transmission may be rotatably coupled to a group of mechanical components 138 or 139, which in turn may be rotatably coupled to a transmission 102. Additionally, in the motor-drive mode, the front-rear differential lock clutch 146 is engaged and the transmission disconnect clutch 147 is disengaged to reduce (e.g., minimize) losses of the mode planetary gear set 104. In a first example, the electric drive 100 provides no power, and the motor drives all wheels, such that the drivetrain has a locked all-wheel drive configuration.In another example, the front-rear differential lock clutch 146 is disengaged, and the transmission disconnect clutch 147 is disengaged. In such an example, the engine drives one of the mechanical components 138 or 139, so that the driveline has a locked two-wheel drive function. Additionally, in such an example, the differential 105 rotates from the non-driven wheels.

[0018] The electric drives described here can be used in cars, trucks, off-road vehicles, commercial vehicles, light vehicles, off-road vehicles, mining vehicles, rail vehicles, manufacturing machinery, industrial machinery and the like.

[0019] The transmission 102 is configured to provide mechanical power to an axle assembly 107 and an axle assembly 109, as explained in detail herein. Thus, the electric drive 100 is configured to provide the vehicle with an all-wheel drive function when the front-rear differential lock clutch 146 is disengaged and a four-wheel drive function when the front-rear differential lock clutch 146 is engaged. The other electric drives and associated transmissions can, of course, also be installed in all-wheel drive vehicles.

[0020] Furthermore, the mode planetary gear set 104 in the example shown is a Ravigneaux gear set. For explanation, the Ravigneaux gear set 104 includes two sets of planetary gears, one set being a simple planetary gear set and the other set being a compound planetary gear set with intermeshing planets in the example shown. However, in other examples, the Ravigneaux gear set may also include a larger number of planetary gear sets. In particular, the Ravigneaux mode planetary gear set 104 includes a first sun gear member 106 and a carrier member 108 with a set of planetary gear members 110 rotatably mounted thereon. However, the mode planetary gear set may also be a compound planetary gear set with intermeshing planets and two-speed functionality, as will be described in more detail with reference to Fig. 6, or the mode planetary gear set may be a simple planetary gear set with two-speed functionality, as described here with respect to Fig. 8 is explained in more detail.

[0021] In the illustrated example, the sun gear 106 meshes with the planet gears in the set of planet gears 110. The mode planetary gear set 104 also includes a ring gear 114, a set of planet gears 116, and a second sun gear 118 in the illustrated example. Furthermore, the ring gear 114 meshes with the planet gears of the set of planet gears 110. Furthermore, in the illustrated example, the planet gears in the second set of planet gears 116 mesh with the sun gear 118 as well as with the gears of the set of planet gears 110. An input shaft 119 is rotatably connected to the sun gear 118 in the illustrated example. Various architectures for providing a rotary input to the mode planetary gear set are explained in more detail in this document.

[0022] In the illustrated example, the mode planetary gear set 104 is specifically configured to switch between three modes. However, electric drivetrains with fewer or greater numbers of gears, such as a two-speed electric transmission, a four-speed electric transmission, a five-speed electric transmission, etc., are also conceivable. To enable the multi-speed functionality of the transmission, a mode clutch 120 is provided in the transmission. The mode clutch 120 is configured to lock the carrier 108 in a first mode, lock the sun gear 106 in a second mode, and rotatably couple the carrier 108 and the sun gear 106 in a third mode. In the illustrated example, the mode clutch 120 is in the second mode. However, the mode clutch 120 can be switched to the various modes depending on the operating conditions of the electric drivetrain and / or the vehicle.Additionally, the first mode has a higher gear ratio than the second mode, and the second mode has a higher gear ratio than the third mode. The specific gear ratios assigned to the modes can be selected based on factors such as the type and performance characteristics of the electric motor, vehicle weight, vehicle performance goals, etc.

[0023] The mode clutch 120 may be a dog clutch, a synchronizer, a friction clutch (e.g., a wet friction clutch), a radial clutch, a face clutch, a cam clutch, a magnetic clutch, combinations thereof, and the like. The other clutches described herein may also be any of the above-mentioned types or combinations of clutch types. Furthermore, the mode clutch 120, as well as the other clutches described herein, may be actuated via electromechanical actuators, pneumatic actuators, hydraulic actuators, electromagnetic actuators, drum cam actuators, combinations thereof, and the like. Shift forks, e.g., translational or rotary shift forks, may be specifically used to actuate at least a portion of the clutches described herein.

[0024] The differential compound intermeshing planetary gear set 105 is rotatably coupled to the mode planetary gear set 104. For illustration, in the example shown, the ring gear member 114 of the mode planetary gear set 104 is coupled to a ring gear member 122 of the differential compound intermeshing planetary gear set 105 via shafts 124 and / or other suitable mechanical components. As further explained herein, a transmission disconnect clutch 147 may be coupled to the shafts 124 to provide a disconnect function between the mode planetary gear set 104 and the differential compound intermeshing planetary gear set 105. By attaching the differential compound intermeshing planetary gear set and the mode planetary gear set in this manner, the transmission can be compactly arranged and a desired gear ratio can be achieved.

[0025] The differential compound planetary gear set with intermeshing planets 105 further includes a set of planet gears 126, a set of planet gears 128, and a sun gear 130. Also included in the differential compound planetary gear set with intermeshing planets 105 is a carrier member 132 to which the set of planet gears 126 and the set of planet gears 128 are rotatably mounted. In the illustrated example, an output shaft 134 is coupled to the carrier member 132, and another output shaft 136 is coupled to the sun gear 130. The output shafts 134 and 136, in turn, are rotatably connected to the axle assemblies 107 and 109 via mechanical components 138 and 139, respectively. The mechanical components 138 and 139 may include joints (e.g., U-joints), shafts, combinations thereof, and the like. The axle arrangements 107 and 109 each include a differential 140 and axle shafts 141 (e.g. half shafts) coupled thereto.The axle shafts 141 are in turn rotatably coupled to drive wheels 142. However, in other examples, the axle shafts 141 may be coupled to wheel-side gear reductions and / or other suitable mechanical components.

[0026] With the electric drive 100 from Fig. 1, the carrier 132 and sun gear 130 of the compound planetary gear set with intermeshing planets 105 act as the transmission outputs, and the sun gear 118 of the Ravigneaux gear set acts as the transmission input. However, front-rear differentials with other output configurations may be used in the electric transmission.

[0027] In the example shown, the mode planetary gear set 104 and the differential compound planetary gear set with meshing planets 105 are concentric to the output rotational axis of the electric drive. This increases the compactness of the electric drive compared to electric drives with a non-concentric arrangement. For reference, a rotational axis 180 of the differential compound planetary gear set with meshing planets 105 is shown in Fig. 1. It is understood that the rotational axis of the input of the mode planetary gear set 104 and the rotational axes of the output shafts 134 and 136 are arranged coaxially with the rotational axis 180.

[0028] The use of the mode planetary gear set 104 and the differential compound planetary gear set with intermeshing planets 105 can allow for the elimination of additional shafts and shift gears from the transmission (if desired), reducing the installation size, narrowing the transmission width, and reducing the overall axial length, enabling a more compact and power-dense electric drive design if desired. Thus, the efficiency of the transmission is increased.

[0029] As previously mentioned, when the planetary gear set 104 is operating in one of the two lower modes (i.e., the first or second mode), a relative velocity exists between the elements of the multi-stage mode planetary gear set. In the third mode, the planetary gear set is locked and rotates as a single unit. The differential compound planetary gear set with intermeshing planets 105 can also typically rotate as a single unit and only differentiates under certain conditions. The majority of the electric drive's life can be in the highest mode for certain end applications, thereby reducing component wear and cooling losses and increasing the efficiency of the electric drive.

[0030] A coordinate axis system is in Fig. 1 and in Fig. 2-9 for reference and, if necessary, for orientation of the views. In one example, the z-axis may be a vertical axis (e.g., parallel to a gravitational axis), the x-axis may be a lateral axis (e.g., a horizontal axis), and the y-axis may be a longitudinal axis. In other examples, the axes may have other orientations. Furthermore, a rotational axis 180 of the sun gear 130 is provided as a reference in Fig. 1. The mode planetary gear set 104 and the differential compound planetary gear set with intermeshing planets 105 are arranged coaxially in the example shown. The other electric transmissions described here also feature the coaxial arrangement between the mode planetary gear set and the differential. In this way, the electric transmission can achieve the desired space efficiency.

[0031] Fig. 1 further shows an electric machine 143 in the electric drive 100. As described here, the electric machines connected to the electric drives may be traction motors (e.g., motor generators). The electric machine 143 of Fig. 1 is specifically arranged concentrically with the differential compound planetary gear set with intermeshing planets 105 and the mode planetary gear set 104. For clarity, an inner diameter 144 of a rotor 145 of the electric machine 143 is shown circumferentially surrounding at least a portion of the transmission and, in particular, the mode planetary gear set 104. However, as explained in more detail herein, the electric machine 143 may have a variety of suitable positions and orientations. In the example shown, at least a portion of the mode planetary gear set 104 is disposed within an internal opening of the electric machine.

[0032] Fig. 1 also shows a front-rear differential lock clutch 146 and a transmission disconnect clutch 147. The differential lock clutch 146 is configured to rotatably couple the carrier 132 and the ring gear 122 within the compound planetary gear set with intermeshing planets 105. In this manner, the compound planetary gear set with intermeshing planets can be selectively locked to increase electric drive performance, particularly in low-traction operating environments (e.g., all-wheel drive). The differential lock clutch 146 enables the output shafts 134 and 136 of the compound planetary gear set with intermeshing planets 105 to be selectively locked from each other. In addition, the transmission disconnect clutch 147 is configured to selectively decouple the ring gear 122 in the differential compound planetary gear set with intermeshing planets 105 and the ring gear 114 in the mode planetary gear set 104.The transmission disconnect clutch 147 enables the differential lock-up planetary gear set with intermeshing planets 105 to be selectively decoupled from the mode planetary gear set 104. One or both of the differential lock clutch 146 and the transmission disconnect clutch 147 can be integrated into one of the transmissions described herein. The transmission disconnect clutch 147 can be used to increase the efficiency of a vehicle's driveline, for example, during towing or in hybrid applications.

[0033] As previously mentioned, the transmission disconnect clutch 147 and the front-rear differential lock clutch 146 may be dog clutches, synchronizers, friction clutches (e.g., wet friction clutches), radial clutches, face clutches, cam clutches, magnetic clutches, combinations thereof, and the like. Furthermore, the transmission disconnect clutch 147 and the differential lock clutch 146 may be actuated via electromechanical actuators, pneumatic actuators, hydraulic actuators, electromagnetic actuators, drum cam actuators, combinations thereof, and the like. Shift forks, e.g., translatory or rotary shift forks, may be specifically used to actuate at least some of the clutches described herein, as previously mentioned.

[0034] Bearings 182 may be coupled to an input shaft 119 of the transmission 102. The input shaft 119 connects the mode planetary gear set 104 to the electric machine 143. As described herein, a bearing may include an inner race, rolling elements (e.g., cylindrical rollers, balls, tapered cylindrical rollers, needle rollers, bushings, etc.), and an outer race. In the illustrated example, a bearing 184 is coupled to the sun gear member 106 in the mode planetary gear set 104. Additionally, a bearing 186 is coupled to the carrier member 108 in the mode planetary gear set. In the illustrated example, another bearing 188 is coupled to the carrier member 108 and the ring gear member 114. Additionally, in the illustrated example, bearings 190 and 198 are coupled to shafts 124 and / or other suitable mechanical structures connected to the ring gear members 114 and 122.A bearing 192 may be coupled to the ring gear 122 and the carrier 132, a bearing 194 may be coupled to the output shaft 136 and the carrier 132, and a bearing 196 may be coupled to the carrier 132. The bearings in the transmission may also be arranged differently in alternative embodiments.

[0035] As in Fig. 1, the EV 103 may also include a control system 150 having a controller 152. The controller 152 may include a microcomputer with components such as a processor 154 (e.g., a microprocessor unit), input / output ports, an electronic storage medium 156 for executable programs and calibration values ​​(e.g., a read-only memory chip, read-only memory, diagnostic memory, a data bus, and the like). The storage medium may be programmed with computer-readable data representing instructions executable by a processor to perform the methods, control techniques, etc. described herein, as well as other variations that are expected but not explicitly listed. Thus, instructions may be stored in the electronic storage medium 156 that, when executed by the processor 154, cause the controller 152 to perform the various method steps described herein.

[0036] The controller 152 may receive various signals from sensors 158 coupled to different areas of the EV 103, and in particular, the electric drive 100. The sensors 158 may include, for example, one or more engine speed sensors (see below), shaft / gear speed sensors, thermocouples, pressure sensors, a pedal position sensor for detecting the depression of a driver-operated pedal (e.g., an accelerator pedal and / or a brake pedal), speed sensors at the vehicle wheels, and the like. An input device 160 (e.g., an accelerator pedal, a brake pedal, a gear selector, combinations thereof, and the like) may also provide input signals indicating the driver's intent for vehicle control.

[0037] After receiving the signals from the various sensors 158 from Fig. 1, the controller 152 processes the received signals and deploys various vehicle component actuators 162 to adjust the components based on the received signals and the instructions stored in the memory of the controller 152. For example, the controller 152 may receive an accelerator pedal signal indicating the driver's request for an adjustment in vehicle acceleration. In response, the controller 152 may command the operation of inverters electrically coupled to an electric machine that supplies power to the mode planetary gear set to increase the power delivered from the engine to the transmission 102. The other controllable components in the vehicle may function similarly, e.g., with respect to sensor signals, control commands, and actuator adjustment. Furthermore, the control system 150 may be employed in any of the electric drive systems and transmissions described herein.

[0038] The controller 152 may include instructions that, when executed, cause the mode clutch 120 to switch between the first mode, the second mode, and the third mode depending on the operating conditions of the vehicle and the electric drive. For example, the electric drive 100 may operate in the first mode when the vehicle is traveling at lower speeds. When the vehicle speed exceeds a first threshold, the mode clutch may switch to the second mode, and when the vehicle speed exceeds a second threshold, the clutch may switch from the second mode to the third mode. This switching sequence may also be performed in reverse order through the modes. Furthermore, the switching sequence does not have to be sequential and may therefore skip modes if desired.For example, the electric drive can be instructed to start in the second mode or to downshift from the third mode to the first mode. The control system 150 described above can be used in any of the electric drives and transmissions described herein.

[0039] Fig. 2-5 show various arrangements of electric machines and gear trains for the input of the mode planetary gear set 104 in various electric drive architectures. The architecture of the mode planetary gear set 104, the differential compound planetary gear set with intermeshing planets 105, the mode clutch 120, the differential lock clutch 146, and the transmission disconnect clutch 147 in the transmission 102 is similar to the component architecture and layout of Fig. 1. A redundant description is therefore omitted for the sake of brevity. Furthermore, it is understood that the arrangements of the electric machine and the input gear train can also be used for the electric drives with mode gear sets described here. Therefore, a redundant description of the overlapping components is omitted for the sake of brevity.

[0040] Fig. In particular, Figure 2 shows an electric drive 200 with an electric machine 202 positioned concentrically with the output shaft 136 and arranged on an outer axial side 204 of the mode planetary gear set 104. A portion of one of the output shafts 136 extends through an opening in the electric machine 202 in the illustrated example. This increases the space efficiency of the electric drive. Fig. 2 further shows bearings 206 coupled to the electric machine 202. The electric drive includes additional bearings with a similar arrangement as in Fig. 1. For example, rotating shafts and gears are generally connected to bearings. The other electric drives from Fig. 3-5 also include a similar bearing arrangement in the mode planetary gear set 104, the differential compound planetary gear set with intermeshing planets 105, the transmission disconnect clutch 147 and the differential lock clutch 146. However, other bearing configurations are also possible.

[0041] Fig. 3 shows an electric drive 300 with two electric machines 301 and 302, each arranged parallel to one of the output shafts 134 and 136 and mechanically connected to the input of the transmission 102 via gear trains 304 and 306. A gear 308 meshes with the gears in each of the gear trains 304 and 306 and establishes a mechanical connection between the input shaft 119 of the mode planetary gear set 104. It is understood that the electric machine 302 and the corresponding gear train 306 are optional and can therefore be omitted from the electric drive in alternative embodiments. In general, a variety of layouts of gear trains connected to the input of the mode planetary gear set can be used. For example, the gear trains used to connect the first electric machine and / or the second electric machine can have fewer or additional gear ratios.In alternative examples, one or more planetary gear sets (e.g., simple planetary gear sets, compound planetary gear sets, and the like) may be used to connect the one or more electric machines to the mode planetary gear set. For example, a planetary gear set coaxial with the electric machine may be used to connect the electric machine to the mode planetary gear set. Additionally or alternatively, a planetary gear set coaxial with the rotational axis of the output shafts 136 may be used to rotatably couple the electric machine to the mode planetary gear set. In all embodiments where one or more planetary gear sets provide the input connection for the mode planetary gear set, a carrier gear in the planetary gear set may be fixed, a ring gear in the planetary gear set may be fixed, or a sun gear in the planetary gear set may be fixed, in various examples.Additional gear stages, chains, belts, combinations thereof, and the like may be used additionally or alternatively to transfer mechanical power between the one or more electric machines and the planetary gear set.

[0042] It should further be understood that any of the electric drives described herein may include a second electric machine, if desired. For example, the second electric machine may be coupled to the input of the mode planetary gear set in the same manner as the mechanical connection between the first electric machine and the input of the mode planetary gear set, in one example. In another example, the second electric machine may be coupled to the input of the mode planetary gear set using a different gearing arrangement to enable a different input ratio between the electric machine and the mode planetary gear set, whereby the second electric machine may have different characteristics than the first electric machine.In addition, a separating clutch may be arranged between the second electric machine and the mode planetary gear set to decouple the second electric machine from the mode planetary gear set and thus further increase efficiency in some cases.

[0043] Fig. 4 shows an electric drive 400 with an electric machine 402 arranged perpendicular to the axis of rotation of the transmission 102. A gear transmission 404 with bevel gears 406 provides the input to the mode planetary gear set 104. As with the exemplary electric drive 300 of Fig. 3, the addition of a second electric machine and a separating clutch for the second electric machine is considered.

[0044] Fig. 5 shows an electric drive 500 with an electric machine 502 arranged perpendicular to the rotational axis of the transmission 102. In the example shown, the electric drive includes an input gear transmission 504 with several reduction ratios 506 and 508, which can be switched via a clutch 510. In this way, the selectable gear in the transmission can be further expanded, which can enable more efficient operation of the electric machine. As with the exemplary electric drive 300 from Fig. 3, the addition of a second electric machine and a disconnect clutch for the second electric machine is contemplated. However, as already mentioned, a variety of gear train layouts are contemplated, providing the input to the mode planetary gear set. In addition, bevel gears 512 are provided in the gear train 504 to connect the gear train to the input shaft 119.

[0045] It is understood that electric drives are conceivable that have the features of combined arrangements of gear transmission and / or motor for two or more Fig. 2-5. Furthermore, any of the various motor and / or input gear arrangements may be used with any of the transmission architectures or combinations of transmission architectures described herein.

[0046] Fig. 6 shows another example of a transmission 600 for an electric drive. The transmission 600 again includes a mode planetary gear set 602 and a differential compound planetary gear set with intermeshing planets 604, which are again arranged coaxially. The differential compound planetary gear set with intermeshing planets 604 is similar in structure and function to the previously described differential compound planetary gear sets with intermeshing planets. Therefore, a redundant description of these gear sets is omitted for the sake of brevity.

[0047] In the illustrated example, the mode planetary gear set 602 is a compound planetary gear set with intermeshing planets. For explanation: In the illustrated example, the mode planetary gear set 602 comprises two sets of planet gears 606 and 608, wherein the planet gears mesh with each other. Furthermore, the planet gears of the planetary gear set 606 mesh with a sun gear 610, and the planet gears of the planetary gear set 608 mesh with a ring gear 612. In other examples, however, the mode planetary gear set can also have a larger number of planetary gear sets and / or a different gear architecture. The sets of planet gears 606 and 608 are rotatably mounted on a carrier 614. Furthermore, an input shaft 615 is connected to the sun gear 610 in the illustrated example. It is understood that the input shaft 615 may be coupled to a traction motor via shafts, gears, chains, belts, combinations thereof, and the like, as previously described.

[0048] The mode planetary gear set 602 can be specifically configured to switch between two modes. However, electric drives with a larger number of gears, such as a three-speed electric drive, a four-speed electric drive, etc., are also conceivable. To enable the multi-speed functionality of the transmission, a mode clutch 616 is provided in the transmission. The mode clutch 616 is configured to lock the carrier 614 in a first mode and to rotatably couple the carrier 614 and the ring gear 612 in a second mode. In the example shown, the mode clutch 616 is in the first mode. However, the mode clutch 616 can be switched to different modes depending on the operating conditions of the electric drive and / or the vehicle. In addition, the first mode has a higher gear ratio than the second mode.The specific gear ratios assigned to the modes can be selected based on factors such as the type and performance characteristics of the electric motor, vehicle weight, vehicle performance objectives, etc.

[0049] As previously discussed, the mode clutch 616 may be a dog clutch, a synchronizer, a friction clutch (e.g., a wet friction clutch), a radial clutch, an end face clutch, a cam clutch, a magnetic clutch, combinations thereof, and the like.

[0050] Fig. Figure 7 shows another example of a transmission 700 for an electric motor. In the example shown, the transmission 700 again includes a differential compound planetary gear set with intermeshing planets 702, similar to the previously described differential compound planetary gear sets with intermeshing planets. The redundant description of the differential compound planetary gear set with intermeshing planets is omitted for clarity.

[0051] The transmission 700 also includes a Ravigneaux-mode planetary gear set 704 with a different architecture than the previously described Ravigneaux-mode planetary gear sets. The Ravigneaux-mode planetary gear set 704 includes a carrier 706 rotatably coupled to a ring gear 708 of the differential compound planetary gear set with intermeshing planets 702. Furthermore, a sun gear 710 in the mode planetary gear set 704, which meshes with a set of planet gears 712, acts as the input of the mode planetary gear set 704. Furthermore, a mode clutch 714 is configured to lock the ring gear 720, which meshes with the planet gears 712, in a first mode, lock the sun gear 716, which meshes with the planet gears 718, in a second mode, and rotatably couple the ring gear 720 and the sun gear 716 in a third mode. The set of planet gears 718 meshes with the set of planet gears 712 in the illustrated example.In this way, the input and output of the mode planetary gear set can be varied. However, other configurations of the planetary gear set are also possible, including arrangements in which the planetary gears 712 comprise a stepped planetary arrangement.

[0052] Fig. 8 shows another example of a transmission 800 for an electric motor. In the example shown, the transmission 800 again includes a differential compound planetary gear set with meshing planets 802. The transmission 800 also includes a mode planetary gear set 804 with a different architecture than the previously described mode planetary gear sets. That is, the mode planetary gear set 804 includes a carrier 806 that is rotatably coupled to a ring gear 808 of the differential compound planetary gear set with meshing planets 802. In addition, a sun gear 810 in the mode planetary gear set 804, which meshes with a set of planet gears 812, acts as the input of the mode planetary gear set 804, as shown in Fig. 8. Further, a mode clutch 814 is configured to lock the ring gear 820, which meshes with gears in the set of planetary gears 812, in a first mode and to rotatably couple the ring gear 820 and the carrier 806 in a second mode.

[0053] Furthermore, the planetary gear sets described herein may take the form of compound planetary gear sets with stepped planets and / or magnetic planetary gear sets. It should also be understood that the additional planetary gear sets (e.g., a simple planetary gear set or a compound planetary gear set with meshing planets) may include a fixed ring gear, a carrier member rotatably coupled to the differential compound planetary gear set with meshing planets, and a sun gear member coupled to a mode planetary gear set. Alternatively, the planetary gear set may include a fixed carrier member, a ring gear member rotatably coupled to the differential compound planetary gear set with meshing planets, and a sun gear member coupled to the mode planetary gear set.

[0054] Fig. Figure 9 shows an electric drive 900 with a transmission having the mode planetary gear set 104 and the differential compound planetary gear set with intermeshing planets 105, which were described above with respect to Fig. 1. However, as described in Fig. 9, a planetary gear set 902 is rotatably coupled to the input shaft 119. In the illustrated example, the planetary gear set 902 is a simple planetary gear set. The planetary gear set 902 includes a fixed ring gear member 904, a carrier member 906 rotatably coupled to the input shaft 119, and a sun gear member 908 coupled to upstream components, such as an electric machine. Alternatively, the planetary gear set 902 may include a fixed carrier member 906, a fixed ring gear member 904 rotatably coupled to the input shaft 119, and a sun gear member 908 coupled to upstream components, such as an electric machine. However, in other examples, the planetary gear set may be a compound intermeshing planetary gear set in which two sets of planet gears mesh with each other.More specifically, a compound intermeshing planetary gear set coupled to the input shaft may be constructed similarly to the components of the differential compound intermeshing planetary gear set 105 with different input and output connections. For example, in the compound intermeshing planetary gear set example, a sun gear member may be coupled to upstream components, a carrier member may be coupled to the input shaft 119, and the ring gear member may be fixed. Alternatively, in the compound intermeshing planetary gear set example, a sun gear member may be coupled to upstream components, a ring gear member may be coupled to the input shaft 119, and the carrier member may be fixed.

[0055] Furthermore, it is understood that the Fig. 1-9 can be further combined with springs, clutches or cones, cam ramps, helical gears, worm gears, spur gears, viscous couplings, gerotors, preloaded friction components and electronic components to create a limited-slip differential (e.g., a torque-sensing limited-slip differential), a limited-slip differential with automatic torque bias, a clutch pack-type limited-slip differential, a bevel gear differential, a dual-sun differential, a reduction differential, etc., and to increase the preload between the front and rear axles, reduce the slip between the front and rear axles and / or create all-wheel drive functionality and thereby increase customer appeal.

[0056] It should be understood that each of the electric drives described herein may, in some examples, include additional gear sets. For example, a planetary gear set (e.g., a simple planetary gear set or a compound planetary gear set with intermeshing planets) may be disposed between the differential compound planetary gear set with intermeshing planets and the mode planetary gear set, or, in other examples, upstream of the mode planetary gear set. As described herein, a simple planetary gear set is a planetary gear set with only a ring gear, a sun gear, and multiple planetary gears that lie in the same plane as the ring gear and sun gear.Furthermore, a compound planetary gear set with intermeshing planets described herein is a planetary gear set having a ring gear, a sun gear, and a plurality of sets of planet gears that mesh in the plane of the ring gear and the sun gear and are circumferentially aligned in the same plane as the ring gear and the sun gear.

[0057] Furthermore, in another application, the compound planetary gear set with meshing planets can have a gear ratio of 2:1, resulting in a 1:1 output. However, changing the planetary gear ratio can result in a torque and speed shift between the front and rear axles. The speed difference between the front and rear axles can be compensated for by different gear ratios in the front and rear differentials. Furthermore, in a compound planetary gear set with meshing planets and preloaded output, the meshing planet gears can always be rotated relative to each other if desired. In general, the electric transmissions described here can have a variety of gear ratios that can be selected based on the end-use goals of the vehicle platform.The ratios shown in the figures are therefore application cases, and different ratios can be used in electric transmissions. Furthermore, the exact position and number of bearings in the electric transmission architectures are specified in . Fig. 1-5 and 9 are suggestive and exemplary, and it should be understood that other bearing arrangements, types, quantities, etc., may be used in alternative examples. Further, the electric transmissions described herein may utilize one or more transverse motors, which in some examples may be coupled to the transmission input via hypoid gears or other suitable bevel gear spirals. In these examples, the motor may be connected to the hypoid gear via a corresponding pinion gear, and additional gear ratios and / or shiftable gears may be located between the motor and pinion gear. The shiftable gears may, in various examples, be disposed on both parallel countershafts. Furthermore, additional gear ratios may be added to the electric transmissions if desired.

[0058] Fig. 1-9 show example configurations with the relative arrangement of the various components. When these elements are in direct contact with each other or are directly coupled, they may be referred to as being in direct contact or directly coupled, respectively, at least in one example. Similarly, elements shown side by side or adjacent to each other may be adjacent to each other or adjacent to each other, at least in one example. For example, components that are in surface-to-surface contact with each other may be referred to as being in surface-to-surface contact. As another example, in at least one instance, elements that are separated from each other with only a space between them and that do not have any other components may be referred to as such.In yet another example, elements depicted above / below, on opposite sides, or to the left / right of each other may be referred to as such, relative to each other. Further, in at least one example, as depicted in the figures, a topmost element or point of an element may be referred to as a "top" of the component, and a bottommost element or point of the element may be referred to as a "bottom" of the component. As used herein, the terms top / bottom, upper / lower, above / below may refer to a vertical axis of the figures and may be used to describe the positioning of elements of the figures relative to each other. Thus, in one example, elements displayed above other elements are arranged vertically above the other elements.As a further example, the shapes of the elements depicted in the figures may be referred to as such (e.g., circular, straight, flat, curved, rounded, beveled, angled, or the like). Furthermore, in one example, elements that are coaxial with one another may be referred to as such. Furthermore, in at least one example, the depicted elements that intersect one another may be referred to as intersecting elements or as intersecting elements. Furthermore, an element depicted inside or outside another element may be referred to as such. In other examples, elements that are offset from one another may also be referred to as such.

[0059] Motor and shift control logic / programs, inverters, electronic control units (ECUs), memory, throttle, brake, speed and incline sensors and the like, shift actuators, etc. can be used in all electric transmissions described here.

[0060] Fig.1-9 provide a method for operating an electric transmission in which the transmission switches between two modes depending on the operating conditions of the vehicle. More specifically, the electric transmission may be a two- or three-speed transmission, as described above. In either configuration, the mode clutch may be actuated to switch the planetary gear set between two different modes. The method may further provide for selectively locking the differential compound planetary gear set with intermeshing planets by actuating a differential lock clutch in the differential planetary gear set. The method may even include selectively disconnecting the electric motor and / or the mode planetary gear set by actuating a disconnect clutch to enable towing options or other motor, hybrid, or BEV vehicle functions to increase customer appeal.

[0061] The invention is further described in the following paragraphs. In one aspect, an electric drive system is provided that includes an electric machine; a multi-speed transmission rotatably coupled to the electric machine, rotatably coupled to two output shafts, and including: a differential gear rotatably coupled to and coaxial with a mode planetary gear set; and a mode clutch configured to switch between two modes. In one example, the mode planetary gear set is a Ravigneaux gear set rotatably coupled to the differential gear; and the mode clutch is selectively configured to: lock a carrier or a ring gear in the Ravigneaux gear set; lock a sun gear in the Ravigneaux gear set; and rotatably couple the carrier or the ring gear to the sun gear in the Ravigneaux gear set.Further, in one example, the ring gear or carrier in the mode planetary gear set may be rotatably coupled to a ring gear or carrier in the differential, and a sun gear in the mode planetary gear set is coupled to an upstream component that receives mechanical power from the electric machine. Furthermore, in one example, the differential may be a differential compound planetary gear set with intermeshing planets. In another example, the differential compound planetary gear set with intermeshing planets may include a carrier rotatably connected to a first output shaft and a sun gear rotatably connected to a second output shaft.In another example, the electric drive system may further include a differential lock-up clutch configured to selectively rotatably couple a ring gear member in the compound planetary gear set with meshing planets to a carrier member in the compound planetary gear set with meshing planets to lock rotation of the two output shafts. In another example, the electric drive system may further include a transmission disconnect clutch configured to selectively disconnect the mode planetary gear set from the differential gearing.In another example, the mode planetary gear set is a compound meshing planetary gear set rotatably coupled to the differential; and the mode clutch is selectively configured to: lock a carrier or a ring gear in the compound meshing planetary gear set; and rotatably couple the carrier to the ring gear in the compound meshing planetary gear set.

[0062] In another aspect, a method of operating an electric drive system is provided, comprising operating a mode clutch to transition between two operating modes; the electric drive system including: an electric machine; a multi-speed transmission rotatably coupled to the electric machine, rotatably coupled to two output shafts, and including: a differential gear rotatably coupled to and coaxial with a mode planetary gear set; and the mode clutch.In one example, the mode planetary gear set may be a Ravigneaux gear set, and the mode clutch is configured to: in a first mode, lock a carrier or a ring gear in the Ravigneaux gear set; in a second mode, lock a sun gear in the Ravigneaux gear set; and in a third mode, rotatably couple the carrier or the ring gear to the sun gear in the Ravigneaux gear set; wherein a transition between two operating modes includes a first mode to a second mode, or a second mode to a third mode.Further, in one example, the mode planetary gear set is a compound intermeshing planetary gear set, and the mode clutch is configured to: in a first mode, lock a carrier or a ring gear included in the compound intermeshing planetary gear set; and in a second mode, rotatably couple the carrier to the ring gear in the compound intermeshing planetary gear set; wherein a transition between two modes includes a first mode to a second mode. Further, in one example, the differential is a differential compound intermeshing planetary gear set.In one example, the method may further include operating a differential lock-up clutch to rotatably couple a ring gear member in the compound intermeshing planetary gear set to a carrier member in the compound intermeshing planetary gear set and lock rotation of the two output shafts. In one example, the method may further include operating a transmission disconnect clutch to selectively disconnect the mode planetary gear set from the differential gear.

[0063] In another aspect, an electric drive system is provided that includes an electric machine; a multi-speed transmission rotatably coupled to the electric machine, rotatably coupled to two output shafts, and including: a differential gear rotatably coupled to and arranged coaxially with a mode planetary gear set; and a mode clutch configured to: lock a carrier or a ring gear in the mode planetary gear set in a first mode, lock a sun gear in the mode planetary gear set in a second mode, and rotatably couple the carrier or the ring gear to the sun gear in the mode planetary gear set in a third mode; or lock a carrier or a ring gear included in the mode planetary gear set in a first mode, and rotatably couple the carrier to the ring gear in a second mode.In one example, the mode planetary gear set may be a Ravigneaux gear set. In yet another example, the mode planetary gear set is a compound planetary gear set with intermeshing planets. In yet another example, the differential may be a differential compound planetary gear set with intermeshing planets. Furthermore, in another example, the electric drive system may further include a differential lock-up clutch configured to selectively rotatably couple a ring gear member in the differential compound planetary gear set with intermeshing planets to a carrier member in the differential compound planetary gear set with intermeshing planets to lock rotation of the two output shafts. In another example, the electric drive system may further include a transmission disconnect clutch configured to selectively disconnect the mode planetary gear set from the differential gear set.

[0064] Furthermore, the electric transmissions described herein may include control systems that include a controller having a processor and a memory storing instructions for performing the method steps described herein. The control methods and routines disclosed herein may be stored as executable instructions in non-transitory memory and executed by a system, including the controller, in combination with the various sensors and actuators. Furthermore, portions of the methods may be physical actions performed in the real world to change the state of a device. The specific routines described herein may represent one or more of any processing strategies, such as event-driven, interrupt-driven, multitasking, multithreading, and the like.Thus, the various actions, operations, and / or functions illustrated can be performed in the order shown, in parallel, or in some cases even without them. Accordingly, the order of processing is not mandatory to achieve the features and advantages of the examples described herein, but is provided for convenience of illustration and description. One or more of the actions, operations, and / or functions illustrated may be performed repeatedly depending on the strategy used. Furthermore, the described actions, operations, and / or functions may graphically represent code to be programmed into the non-transitory memory of the computer-readable storage medium in the control system, wherein the described actions are carried out by execution of the instructions in a system including the various hardware components in combination with the electronic controller.One or more of the process steps described here can be omitted if desired.

[0065] While various embodiments have been described above, these are to be considered examples and not restrictions or limitations. It should be understood that the configurations and operations disclosed herein are exemplary, and these specific examples are not to be considered limiting, as numerous variations are possible. For example, the technology described above may be applied to powertrains that include various types of power sources, including various types of electric machines, internal combustion engines, and / or transmissions. The technology may be used as a standalone system or in combination with other power transfer systems not applicable to electric vehicle machines and propulsion systems (e.g., HEVs, BEVs, etc.).), agricultural vehicles or machines, watercraft or machines, motorcycles, recreational vehicles, on- and off-highway vehicles, mining vehicles, rail vehicles, production machines, industrial machines, etc. The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations, as well as other features, functions, and / or properties disclosed herein. Those skilled in the art will appreciate that the disclosed subject matter may be embodied in other specific forms without departing from the spirit of the subject matter.

[0066] The following claims particularly point out certain combinations and subcombinations that are considered novel and non-obvious. These claims may refer to "a" element or "a first" element, or the equivalent thereof. Such claims are to be construed as including the inclusion of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and subcombinations of the disclosed features, functions, elements, and / or properties may be claimed by amending the present claims or by filing new claims in this or a related application. Such claims, whether broader, narrower, equal, or different in scope than the original claims, are also to be considered included within the subject matter of the present disclosure. QUOTES CONTAINED IN THE DESCRIPTION

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

[0000] US 63 / 515,754

[0001]

Claims

[1] Electric drive system comprising: an electrical machine; a multi-speed gearbox rotatably connected to the electric machine, rotatably connected to two output shafts and including: a differential gear rotatably coupled to and coaxial with a mode planetary gear set; and a mode clutch configured to switch between two operating modes. [2] Electric drive system according to claim 1, wherein: the mode planetary gear set is a Ravigneaux gear set rotatably coupled to the differential gear; and the mode clutch is optionally configured to: Locking a carrier or a ring gear in the Ravigneaux gear set; Locking a sun gear in the Ravigneaux gear set; and rotatable coupling of the carrier or ring gear to the sun gear in the Ravigneaux gear set. [3] The electric drive system of claim 2, wherein the ring gear or the carrier in the mode planetary gear set is rotatably coupled to a ring gear or the carrier in the differential gear, and a sun gear in the mode planetary gear set is coupled to an upstream component that receives mechanical power from the electric machine. [4] The electric drive system of claim 1, wherein the differential is a differential compound planetary gear set with intermeshing planets. [5] The electric drive system of claim 4, wherein the differential compound planetary gear set with intermeshing planets includes a carrier rotatably connected to a first output shaft and a sun gear rotatably connected to a second output shaft. [6] The electric drive system of claim 4, further comprising a differential lock-up clutch configured to selectively rotatably couple a ring gear member in the differential compound planetary gear set with intermeshing planets to a carrier member in the differential compound planetary gear set with intermeshing planets to lock rotation of the two output shafts. [7] The electric drive system of claim 1, further comprising a transmission disconnect clutch configured to selectively disconnect the mode planetary gear set from the differential gear. [8] Electric drive system according to claim 1, wherein: the mode planetary gear set is a compound planetary gear set with intermeshing planets rotatably coupled to the differential; and the mode clutch is optionally configured to: Locking a carrier or a ring gear in the compound planetary gear set with meshing planets; and rotatable coupling of the carrier to the ring gear in the compound planetary gear set with intermeshing planets. [9] The electric drive system of claim 1, wherein the mode planetary gear set is a Ravigneaux gear set. [10] The electric drive system of claim 1, wherein the mode planetary gear set is a compound planetary gear set having intermeshing planets. [11] The electric drive system of claim 1, wherein the differential is a differential compound planetary gear set with intermeshing planets. [12] An electric drive system according to claim 11, further comprising: a differential lock-up clutch configured to selectively rotatably couple a ring gear in the differential compound planetary gear set with intermeshing planets to a carrier in the differential compound planetary gear set with intermeshing planets to lock rotation of the two output shafts. [13] An electric drive system according to claim 12, further comprising: a transmission disconnect clutch configured to selectively disconnect the mode planetary gear set from the differential gear.

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