Electric drive system

Abstract

The utility model relates to an electric drive system. In one example, an electric drive system includes an electric machine and a multi-speed transmission rotationally coupled to the electric machine, rotationally coupled to two output shafts. A multi-speed transmission includes a differential meshing planetary compound planetary gear set rotationally coupled and coaxially positioned with a mode planetary gear set, and a mode clutch configured to switch between two operating modes.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 515,754, filed on July 26, 2023, entitled “All-Wheel Drive Electric Transmission,” which is hereby incorporated by reference in its entirety. Technical Field

[0003] This note is about power transmission. Background Art

[0004] Electric transmissions (EVs) are being adopted across various vehicle platforms to address electrification needs in diverse vehicle segments. These EVs consist of a traction motor and gear train, which can be installed in various configurations depending on the vehicle platform's space constraints and intended end-use. In some cases, EVs offer greater flexibility in powertrain architecture than electric axles.

[0005] At least some electric transmissions have failed to achieve their end-use design goals in terms of space efficiency, shifting functionality, and power density. For example, some multi-speed transmissions use a large number of parallel shafts and gears, which presents packaging challenges. Furthermore, in previous multi-speed transmissions, all gears are meshed, but in certain modes, torque is transmitted through only some gears, while others are unloaded. Consequently, these unloaded gears create unavoidable bearing, meshing, and airflow losses. Therefore, the inventors recognized the desire to reduce packaging space and increase the power density of electric transmissions. Utility Model Content

[0006] The above problems can be at least partially solved by an electric drive system. In one example, the electric drive system includes an electric motor and a multi-speed transmission, which is rotationally coupled to the electric motor and rotationally coupled to two output shafts. The multi-speed transmission includes a differential (e.g., a differential meshing planetary compound planetary gear set) that is rotationally coupled and positioned coaxially with the mode planetary gear set. The multi-speed transmission also includes a mode clutch that can switch between two operating modes. In this way, the mode planetary gear set effectively realizes multiple gear ratio modes in a space-saving package, thereby expanding the system's speed change capability. In addition, the coaxial arrangement of the differential and the mode planetary gear set can reduce the axial length of the electric drive device as needed.

[0007] In one example, the mode planetary gear set can be a Ravigneaux gear set rotationally coupled to a differential. Furthermore, a 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 rotationally couple the carrier or ring gear in the Ravigneaux gear set to the sun gear. In this way, the Ravigneaux gear set can effectively achieve three gear ratio modes.

[0008] In another example, a mode clutch is configured to selectively shift the mode planetary gear set into a first mode, in which the mode clutch holds the carrier or ring gear in the mode planetary gear set stationary, and a second mode, in which the mode clutch rotationally couples the carrier to the ring gear. In this manner, the meshing planet compound planetary gear set achieves dual-speed functionality in a compact package, making it easier to integrate into various vehicle designs.

[0009] It should be understood that the above summary is intended to introduce concepts further described in the detailed description in a simplified form. It is not intended to identify key or essential features of the claimed subject matter, the scope of which is determined solely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 An electric vehicle is shown, whose electric drive comprises a gearbox with a modal planetary gear set.

[0011] Figure 2-5 Different motor and gear train layouts in different electric drive architectures are shown.

[0012] Figure 6-8 The planetary gear set configurations for different modes in an exemplary electrically variable transmission are shown.

[0013] Figure 9 An electrically variable transmission is shown with a planetary gear set providing input to a modal planetary gear set. DETAILED DESCRIPTION

[0014] The differentiated multi-speed electric transmission (e.g., a differentiated multi-speed all-wheel drive electric transmission) described herein has a mode selection function that enables higher compactness and power density. Furthermore, in one example, the electric transmission can utilize a north-south architecture. To achieve space efficiency and power density targets, the electric transmission includes a transmission having a multi-speed mode planetary gear set and a differential in a coaxial package. Specifically, the multi-speed gear set in the electric transmission includes a mode planetary gear set with a mode clutch for shifting between gear modes.

[0015] In the first mode of an electric transmission, relative speeds exist between the elements of the multi-speed planetary gearset. In the highest mode of an electric transmission (e.g., the second mode of a two-speed transmission or the third mode of a three-speed transmission), the multi-speed planetary gearset is locked and rotates as a unit. In actual applications, the transmission may operate in the highest mode for a longer period of time (e.g., most of the time) than in the lower speed modes. In the highest operating mode, there is no relative rotation of components within the differential or within the multi-speed planetary gearset, resulting in reduced component wear, increased component life, reduced friction losses, and reduced airflow losses, thereby improving the overall efficiency of the transmission.

[0016] Furthermore, in an electric transmission, the transfer member can be formed as a meshing planetary compound gear set. The electric transmission can passively distribute mechanical power from an electric motor or other suitable central power source to multiple axle differentials (e.g., front and rear axle differentials). This eliminates the need for multiple independent electric axles, multiple power inverters, and associated auxiliary electronics (if required). Consequently, the size and complexity of the electric transmission are reduced, and the power density of the electric transmission is increased, thereby increasing its customer appeal. The electric transmission can be front-mounted, mid-mounted, or rear-mounted, providing design flexibility. Furthermore, in one example, the front or rear electric transmission output can be further actively braked to transfer more power to the opposing front or rear axle differential. Furthermore, in one example, the electric transmission described herein can be used with a solid axle, an independent suspension system, or a combination of both types of axles.

[0017] In one example, the electric transmission can be in the form of a two-speed transmission, wherein the modal planetary gear set is a meshing planetary compound gear set consisting of two sets of planetary gears, which mesh with a ring gear and a sun gear and are arranged circumferentially in the same plane. In this way, in one example, the electric transmission compactly achieves high power density two-speed functionality, and the output rotation direction of each mode is the same as the input rotation direction of a simple planetary multi-speed transmission.

[0018] In another example, the electric transmission can be specifically implemented as a three-speed transmission, in which the modal planetary gearset is a Ravigneaux planetary gearset. In a Ravigneaux planetary gearset, the meshing planets of the compound planetary gearset and the simple planetary gearset share a common ring gear and planetary gears (or stepped planetary gears). Furthermore, in a Ravigneaux planetary gearset, the two sun gears can mesh with two sets of planetary gears, respectively. This expands the transmission's modal characteristics within a compact, high-power-density transmission architecture.

[0019] Through the above-mentioned layout of the electric transmission, the transmission separation clutch and / or the front and rear differentiated lockup clutch can be conveniently and effectively integrated into the transmission, thereby realizing additional functions that are difficult to integrate on a single electric axle.

[0020] Figure 1 An example of an electric drive 100 is shown with a transmission 102 that includes a modal 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., front and rear differentials). Figure 1 In the figure, the differential 105 is specifically shown as a split meshing planetary compound planetary gear set, and is therefore also called a split meshing planetary compound planetary gear set. However, it is understood that other types of differentials can be used instead. Figure 1 The differential meshing planetary compound planetary gear set shown in FIG and other differential meshing planetary compound planetary gear sets described herein. For example, the differential can be a double sun gear differential (configurable as an open differential or a limited slip differential), a bevel gear differential, a reduction differential, etc., as described in detail herein. The modal planetary gear set 104 and the differential meshing planetary compound planetary gear set 105 are discussed in detail herein.

[0021] In the illustrated example, electric drive 100 is included in electric vehicle (EV) 103. It will be appreciated that the other electric drive devices described herein may also be included in similar electric vehicles. Electric vehicle 103 may be an all-electric vehicle (e.g., a battery electric vehicle (BEV)) in one example, or a hybrid electric vehicle in another example. Thus, in some examples, a vehicle utilizing the electric drive devices described herein may also include an internal combustion engine (e.g., a spark-ignition engine, a compression-ignition engine, a combination thereof, etc.).

[0022] In an HEV example, the engine can be used in conjunction with a transmission and arranged in parallel with mechanical components 138 or 139 (discussed in greater detail herein). Continuing with the hybrid vehicle example, in engine propulsion mode, the engine can be rotationally coupled to the transmission, and the transmission can be rotationally coupled to either set of mechanical components 138 or 139. Furthermore, in engine propulsion mode, lockup clutch 146 is engaged and mode clutch 147 is disengaged to reduce (e.g., minimize) losses in mode planetary gearset 104. In the first example, the engine propels all wheels, allowing the powertrain to exhibit locked four-wheel drive functionality. In another example, another disconnect clutch can be provided between the transmission coupled to the transmission and the electric transmission. In this example, the additional disconnect clutch is disengaged, and the engine powers one of the axle differentials. Furthermore, in such an example, the mode gearset can be disengaged, but differential 105 rotates away from the unpowered wheels.

[0023] The electric drive devices described herein may be used in automobiles, trucks, all-terrain vehicles (ATVs), commercial vehicles, light vehicles, off-highway vehicles, mining vehicles, rail vehicles, manufacturing machinery, industrial machinery, and the like.

[0024] Transmission 102 is designed to provide mechanical power to axle assembly 107 and axle assembly 109, as discussed in greater detail herein. Thus, electric drive unit 100 provides all-wheel drive functionality for the vehicle. It will be appreciated that other electric drive units and their associated transmissions may also be integrated into an all-wheel drive vehicle.

[0025] Furthermore, in the illustrated example, the modal planetary gear set 104 is a Ravigneaux gear set. Specifically, the Ravigneaux gear set 104 includes two sets of planetary gears, one of which is a simple planetary gear set and the other is a meshing planetary compound gear set. However, in other examples, the Ravigneaux gear set may have more planetary gear sets. Specifically, in the example, the Ravigneaux modal planetary gear set 104 includes a first sun gear 106 and a carrier 108, on which a set of planetary gears 110 are rotatably mounted. However, the modal planetary gear set may also be a meshing planetary compound planetary gear set having a two-speed function, such as Figure 6 As stated.

[0026] In the illustrated example, sun gear 106 meshes with the planet gears in planetary gear set 110. In the illustrated example, modal planetary gear set 104 also includes a ring gear 114, a set of planet gears 116, and a second sun gear 118. Furthermore, in the illustrated example, ring gear 114 meshes with the planet gears in planetary gear set 110. In the illustrated example, the planet gears in the second set of planet gears 116 mesh with sun gear 118 and the gears in planet gear set 110. In the illustrated example, input shaft 119 is rotationally coupled to sun gear 118. Various structures that provide rotational input to the modal planetary gear set will be described in detail herein.

[0027] In the illustrated example, the mode planetary gearset 104 is specifically configured to shift between three modes. However, electric transmissions with fewer or more speeds are also contemplated, such as two-speed electric transmissions, four-speed electric transmissions, and five-speed electric transmissions. To achieve the transmission's multi-speed functionality, a mode clutch 120 is provided within the transmission. The mode clutch 120 is configured to secure the carrier 108 in a first mode, secure the sun gear 106 in a second mode, and rotationally couple the carrier 108 and 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 different modes depending on the operating conditions of the electric drive and / or vehicle. Furthermore, the first mode has a higher gear ratio than the second mode, which in turn has a higher gear ratio than the third mode. The specific gear ratios associated with each mode can be selected based on factors such as the motor type and performance characteristics, vehicle weight, and vehicle performance targets.

[0028] The mode clutch 120 can be a dog clutch, a synchronizer, a friction clutch (e.g., a wet friction clutch), a radial clutch, a face clutch, a crank clutch, a magnetic clutch, and combinations thereof. Other clutches described herein can also be any of the above-mentioned types of clutches or combinations of clutch types. In addition, the mode clutch 120 and other clutches described herein can be actuated by electromechanical actuators, pneumatic actuators, hydraulic actuators, electromagnetic actuators, barrel cam actuators, combinations thereof, etc. A shift fork, such as a translational or rotary shift fork, can be specifically used to drive at least a portion of the clutches described herein.

[0029] The differential meshing planetary compound gear set 105 is rotationally coupled to the pattern planetary gear set 104. Specifically, in the illustrated example, the ring gear 114 of the pattern planetary gear set 104 is coupled to the ring gear 122 of the differential meshing planetary compound gear set 105 via a shaft 124 and / or other suitable mechanical components. As discussed in more detail herein, a transmission disconnect clutch 147 can be connected to the shaft to provide a disconnect function between the pattern planetary gear set 104 and the differential meshing planetary compound gear set 105. Connecting the differential meshing planetary compound gear set and the pattern planetary gear set in this manner allows for a compact transmission layout and desired gear ratios.

[0030] The differential meshing planetary compound gear set 105 also includes a set of planet gears 126, a set of planet gears 128, and a sun gear 130. The differential meshing planetary compound gear set 105 also includes a carrier 132 on 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 connected to the carrier 132, and another output shaft 136 is connected to the sun gear 130. Output shafts 134 and 136 are, in turn, rotationally coupled to axle assemblies 107 and 109, respectively, via mechanical assemblies 138 and 139. Mechanical assemblies 138 and 139 may include joints (e.g., U-joints), shafts, or combinations thereof. Axle assemblies 107 and 109 each include a differential 140 and an axle shaft 141 (e.g., axle shaft) connected thereto. Axle shafts 141, in turn, are rotationally coupled to drive wheels 142. However, in other examples, axle 141 may be coupled to a wheel-end gear reducer and / or other suitable mechanical components.

[0031] exist Figure 1 In the illustrated electric transmission 100, the carrier 132 and sun gear 130 of the differential meshing planetary compound gear set 105 serve as the output of the transmission, and the sun gear 118 of the Ravigneaux gear set serves as the input of the transmission. However, differential meshing planetary compound gear sets with different output configurations may also be used in electric transmissions.

[0032] In the example shown, the mode planetary gear set 104 and the differential meshing compound planetary gear set 105 are concentric with the output rotation axis of the electric machine, so that the structure of the electric machine is more compact than that of an electric machine with a non-concentric arrangement. Figure 1 The rotation axis 180 of the differential meshing planetary compound gear set 105 is provided for reference. It is understood that the rotation axis of the input end of the mode planetary gear set 104 and the rotation axes of the output shafts 134 and 136 are coaxially arranged with the rotation axis 180.

[0033] The use of the mode planetary gear set 104 and the differential meshing planetary compound planetary gear set 105 can eliminate additional shafts and shift gears in the transmission (if necessary), reduce packaging, reduce transmission width, and reduce overall axial length, thereby achieving a more compact and power-dense electric drive design (if necessary). In this way, the efficiency of the transmission is improved.

[0034] As described above, when the modal planetary gear set 104 operates in one of the two lower modes (i.e., the first mode or the second mode), relative speeds exist between the elements of the multi-speed modal planetary gear set. In the third mode, the modal planetary gear set is locked and rotates as a unit. The differential also typically rotates as a unit, with the differential only being split under specific conditions. In certain end-use platforms, the electric drive may spend most of its life in the highest mode, thereby reducing component wear, lowering airflow losses, and improving the efficiency of the electric drive.

[0035] Figure 1 as well as Figure 2-9 A coordinate axis system is provided for reference and, when appropriate, orientation of a view. In one example, the Z axis can be the vertical axis (e.g., parallel to the axis of gravity), the X axis can be the lateral axis (e.g., horizontal), and the Y axis can be the longitudinal axis. However, in other examples, these axes can have other orientations. Figure 1 The rotation axis 180 of the sun gear 130 is also provided for reference. In the illustrated example, the modal planetary gearset 104 and the differential meshing compound planetary gearset 105 are coaxially arranged. Other electrically driven transmissions described herein also employ a coaxial arrangement of the modal planetary gearset and the differential. This arrangement allows the electrically driven transmission to achieve ideal space efficiency.

[0036] Figure 1 Further depicted is an electric motor 143 in electric drive 100. As described herein, an electric motor associated with an electric drive may be a traction motor (eg, a motor generator). Figure 1 The motor 143 is depicted as being concentric with the indexing, meshing, compound planetary gearset 105 and the modal planetary gearset 104. Specifically, the motor 143 is shown with its rotor 145 having an inner diameter 144 that surrounds at least a portion of the transmission, particularly the modal planetary gearset 104. However, as discussed in greater detail herein, the motor 143 can have a variety of suitable locations and orientations. In the illustrated example, at least a portion of the modal planetary gearset 104 is positioned within an internal opening of the motor.

[0037] Figure 1Also described are a differential locking clutch 146 and a transmission disconnect clutch 147. The differential locking clutch 146 is configured to rotationally couple the carrier 132 and the ring gear 122 within the differential meshing planetary compound gear set 105. This allows the differential meshing planetary compound gear set to be selectively locked to enhance electric drive performance, particularly in low-traction operating environments (e.g., four-wheel drive applications). The differential locking clutch 146 allows the output shafts 134 and 136 of the differential meshing planetary compound gear set 105 to be selectively locked for relative rotation. Furthermore, the transmission disconnect clutch 147 is configured to selectively decouple the ring gear 122 within the differential meshing planetary compound gear set 105 from the ring gear 114 within the pattern planetary gear set 104. The transmission disconnect clutch 147 selectively disconnects the differential meshing planetary compound gear set 105 from the pattern planetary gear set 104. One or both of the differential locking clutch 146 and the transmission disconnect clutch 147 may be incorporated into any transmission described herein. The transmission disconnect clutch 147 may improve the efficiency of the vehicle driveline, such as for traction or hybrid applications.

[0038] As described above, the transmission disconnect clutch 147 and the differential locking clutch 146 can be dog clutches, synchronizers, friction clutches (e.g., wet friction clutches), radial clutches, face clutches, crank clutches, magnetic clutches, combinations thereof, etc. In addition, the transmission disconnect clutch and the differential locking clutch can be actuated by electromechanical actuators, pneumatic actuators, hydraulic actuators, electromagnetic actuators, barrel cam actuators, combinations thereof, etc. As previously described, a shift fork, such as a translating or rotating shift fork, can be specifically used to actuate at least a portion of the clutches described herein.

[0039] Bearing 182 can be connected to the input shaft 119 of the transmission 102. Input shaft 119 connects the modal planetary gearset 104 and the motor 143. As described herein, a bearing can include inner races, roller elements (e.g., cylindrical rollers, spherical balls, tapered cylindrical rollers, needle rollers, bushings, etc.), and outer races. In the illustrated example, bearing 184 is connected to the sun gear 106 of the modal planetary gearset 104. Furthermore, one bearing 186 is connected to the carrier 108 of the modal planetary gearset. In the illustrated example, another bearing 188 is connected to the carrier 108 and the ring gear 114. Furthermore, in the illustrated example, bearings 190 and 198 are connected to shaft 124 and / or other suitable mechanical structures, which are connected to the ring gears 114 and 122. Bearing 192 can be connected to the ring gear 122 and the carrier 132, bearing 194 can be connected to the output shaft 136 and the carrier 132, and bearing 196 can be connected to the carrier 132. In other embodiments, the bearings in the transmission may have other suitable arrangements.

[0040] like Figure 1 As shown, the electric vehicle 103 may further include a control system 150 having a controller 152. The controller 152 may include a microcomputer having a processor 154 (e.g., a microprocessor unit), input / output ports, and an electronic storage medium 156 (e.g., a read-only memory chip, random access memory, survivability memory, a data bus, etc.) for executable programs and calibration values. The storage medium may be programmed with computer-readable data representing instructions that are executable by the processor for performing the methods, control techniques, etc. described herein, as well as other variations that are anticipated but not specifically listed. Thus, the electronic storage medium 156 may store instructions that, when executed by the processor 154, cause the controller 152 to perform the various method steps described herein.

[0041] The controller 152 may receive various signals from sensors 158 that are connected to various areas of the electric vehicle 103, and in particular, the electric drive 100. For example, the sensors 158 may include one or more motor speed sensors (described in detail below), shaft / gear speed sensors, thermocouples, pressure sensors, pedal position sensors for detecting operator depression of actuated pedals (e.g., an accelerator pedal and / or a brake pedal), wheel speed sensors, etc. Input devices 160 (e.g., an accelerator pedal, a brake pedal, a gear selector, combinations thereof, etc.) may further provide input signals indicative of the operator's vehicle control intent.

[0042] Upon receiving Figure 1 After receiving signals from various sensors 158, the controller 152 processes the received signals and uses various actuators 162 of vehicle components to adjust the components based on the received signals and instructions stored in the memory of the controller 152. For example, the controller 152 can receive an accelerator pedal signal indicating that the operator requests an adjustment in vehicle acceleration. In response, the controller 152 can command operation of an inverter electrically coupled to the motor that provides power to the mode planetary gear set to increase the power delivered from the motor to the transmission 102. For example, other controllable components in the vehicle can function in a similar manner in terms of sensor signals, control commands, and actuator adjustments. In addition, the control system 150 can be used with any of the electric drive systems and transmissions described herein.

[0043] 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 according to the operating conditions of the vehicle and the electric drive. For example, when the vehicle is traveling at a lower speed, the electric drive 100 may operate in the first mode. 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 shifting sequence may also be executed in reverse order by mode. In addition, the shifting sequence may be performed out of sequence, so that modes may be skipped as needed. For example, the electric drive may be commanded to start in the second mode, or to downshift from the third mode to the first mode. The control system 150 described above may be used for any electric drive and transmission described herein.

[0044] Figure 2-5 The different motor and gear train arrangements for the input mode planetary gear set 104 in different electric drive configurations are described. The configurations of the mode planetary gear set 104, the differential meshing planetary compound gear set 105, the mode clutch 120, the differential locking clutch 146 and the transmission disconnect clutch 147 are shown in FIG. Figure 1 The components shown are similar in structure and layout. Therefore, redundant descriptions have been omitted for the sake of brevity. Furthermore, it will be appreciated that the motor and input gear train arrangements described herein are applicable to electric drives with modal gear sets. Therefore, redundant descriptions of overlapping components have been omitted for the sake of brevity.

[0045] Figure 2 Specifically shown is an electric drive 200, whose motor 202 is concentric with the output shaft 136 and is located on the outer axial direction 204 of the mode planetary gear set 104. In the example shown, a portion of the output shaft 136 passes through the opening of the motor 202. In this way, the space efficiency of the electric mechanism is improved. Figure 2 Further shown is a bearing 206 connected to the motor 202. The electric drive includes additional bearings arranged similarly to the Figure 1 For example, rotating shafts and gears generally have bearings attached to them. Figure 3-5 The other electric drive units shown also include similar bearing arrangements in the modal planetary gear sets, differential meshing planetary compound gear sets, drive disconnect clutches, and differential locking clutches. However, other bearing arrangements may also be used.

[0046] Figure 3An electric drive 300 is shown with two motors 301 and 302, each 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. Gear 308 meshes with a gear in each gear train 304 and 306 and provides a mechanical connection between the input shaft 119 of the modal planetary gear set. It will be appreciated that the electric motors 302 and the corresponding gear trains 306 are optional and, therefore, may be omitted in other embodiments. More generally, various gear train arrangements connected to the input of the modal planetary gear set may be used. For example, the gear trains used to connect the first motor and / or the second motor may include additional gear paths. In other examples, one or more planetary gear sets (e.g., simple planetary gear sets, compound planetary gear sets, etc.) may be used to connect one or more motors to the modal planetary gear set. For example, a planetary gear set coaxial with the motor may be used to connect the motor to the modal planetary gear set. Furthermore, a planetary gear set coaxial with the axis of rotation of the output shaft 136 may also be used to rotationally couple the motor to the modal planetary gear set. In any embodiment where one or more planetary gear sets provide an input connection to a modal planetary gear set, the carrier of the planetary gear set can be fixed, the ring gear of the planetary gear set can be fixed, or the sun gear of the planetary gear set can be fixed. Furthermore, additional gear transmissions, chains, belts, combinations thereof, etc., can be used to transmit mechanical power between the one or more motors and the modal planetary gear set.

[0047] Furthermore, it will be appreciated that any of the electric drives described herein can include a second motor, if desired. For example, in one example, the second motor can be connected to the input of the modal planetary gearset in the same manner as the mechanical connection formed between the first motor and the input of the modal planetary gearset. In another example, the second motor can be connected to the input of the modal planetary gearset using a different gear arrangement to achieve a different motor-to-modal planetary gearset input ratio, thereby giving the second motor different characteristics than the first motor. Furthermore, in some cases, a disconnect clutch can be positioned between the second motor and the modal planetary gearset to decouple the second motor from the modal planetary gearset, further improving efficiency.

[0048] Figure 4 An electric drive 400 is shown with an electric motor 402 arranged perpendicular to the axis of rotation of the transmission 102. A gear train 404 including bevel gears 406 provides input to the modal planetary gear set 104. Figure 3 Similar to the exemplary electric drive apparatus 300 described in

[0045] , consider the addition of a second electric machine and a second electric machine disconnect clutch.

[0049] Figure 5An electric drive 500 is shown with an electric motor 502 arranged perpendicular to the axis of rotation of the transmission 102. In the illustrated example, the electric drive comprises an input gear train 504 with a plurality of gear reducers 506 and 508, which can be selected via a clutch 510. This allows the selection of gears in the transmission to be further expanded, thereby making the operation of the electric machine more efficient. Figure 3 Similar to the exemplary electric drive 300 described in

[15] , the addition of a second electric machine and a second electric machine disconnect clutch is also contemplated. However, as described above, various gear train configurations are also contemplated that can provide inputs to the modal planetary gear sets. Furthermore, bevel gear 512 is provided within gear train 504 to connect the gear train to input shaft 119.

[0050] It is understood that the electric drive device includes Figure 2-5 Furthermore, any different motor and / or input gear train arrangements may be used with any transmission structure or combination of transmission structures described herein.

[0051] Figure 6 Another example of a transmission 600 for electric drive is shown. This transmission again includes a coaxially arranged modal planetary gear set 602 and a differential meshing planetary compound gear set 604. The differential meshing planetary compound gear set 604 is similar in structure and function to the differential meshing planetary compound gear sets described previously. Therefore, for the sake of brevity, redundant descriptions of these gear sets are omitted.

[0052] In the illustrated example, the modal planetary gear set 602 is a meshing planetary compound gear set. Specifically, in the illustrated example, the modal planetary gear set 602 includes two sets of planetary gears 606 and 608, wherein the planetary gears are meshed with each other. In addition, the planetary gears in the planetary gear set 606 are meshed with the sun gear 610, and the planetary gears in the planetary gear set 608 are meshed with the ring gear 612. However, in other examples, the modal planetary gear set may have more planetary gear sets and / or different gear structures. The planetary gear sets 606 and 608 are rotatably mounted on a carrier 614. In addition, in the illustrated example, an input shaft 615 is connected to the sun gear 610. It will be understood that, as previously described, the input shaft 615 can be connected to the traction motor via a shaft, gear transmission, chain, belt, a combination thereof, or the like.

[0053] The mode planetary gear set 602 can be specifically configured to switch between two modes. However, electric drives with more speeds are also considered, such as three-speed electric drives, four-speed electric drives, etc. In order to achieve the multi-speed function of the transmission, a mode clutch 616 is provided in the transmission. The mode clutch 616 is configured to fix the bracket 614 in the first mode and to rotationally couple the bracket 614 and the ring gear 612 in the second mode. In the illustration, 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 gear ratio of the first mode is higher than that of the second mode. The specific gear ratio associated with the mode can be selected based on factors such as the type and performance characteristics of the motor, the weight of the vehicle, and the performance goals of the vehicle.

[0054] As previously described, the mode clutch 616 can be a dog clutch, a synchronizer, a friction clutch (eg, a wet friction clutch), a radial clutch, a face clutch, a crank clutch, a magnetic clutch, combinations thereof, and the like.

[0055] Figure 7 Another example of a transmission 700 for electric drive is shown. In the illustrated example, the transmission 700 again includes a differential meshing planetary compound planetary gear set 702 similar to the differential meshing planetary compound planetary gear set described previously. For the sake of brevity, redundant descriptions of the differential meshing planetary compound planetary gear set are omitted.

[0056] Transmission 700 also includes a Ravigneaux modal planetary gearset 704, whose structure differs from the previously described Ravigneaux modal planetary gearset. Specifically, Ravigneaux modal planetary gearset 704 includes a carrier 706 rotationally coupled to a ring gear 708 of the differential meshing planetary compound planetary gearset 702. Furthermore, a sun gear 710 in modal planetary gearset 704 meshes with a set of planetary gears 712, serving as the input of modal planetary gearset 704. Furthermore, a modal clutch 714 is configured to fix a ring gear 720 meshing with planetary gears 712 in a first mode, fix a sun gear 716 meshing with planetary gears 718 in a second mode, and rotationally couple ring gear 720 and sun gear 716 in a third mode. In the illustrated example, a set of planetary gears 718 meshes with a set of planetary gears 712. In this manner, the input and output of the modal planetary gearset can be varied. However, other planetary gear set configurations may be employed, including arrangements in which the planet gears 712 include stepped planetary assemblies.

[0057] Figure 8Another example of a transmission 800 for electric drive is shown. In the illustrated example, transmission 800 further includes a differentially meshing planetary compound gear set 802. Transmission 800 also includes a modal planetary gear set 804, which has a different structure than the previously described modal planetary gear sets. Furthermore, a sun gear 810 in modal planetary gear set 804 meshes with a set of planetary gears 812, which serve as inputs to modal planetary gear set 804. Furthermore, a modal clutch 814 is configured to secure a ring gear 820 meshing with a gear in planetary gear set 812 in a first mode, and to rotationally couple ring gear 820 to carrier 806 in a second mode.

[0058] Furthermore, the planetary gear sets described herein may take the form of stepped planetary compound gear sets and / or magnetic planetary gear sets. It is also understood that additional planetary gear sets (e.g., simple planetary gear sets or meshing planetary compound gear sets) may include a fixed ring gear, a carrier rotationally coupled to a differential meshing planetary compound gear set, and a sun gear coupled to a modal planetary gear set. Alternatively, the planetary gear set may include a fixed carrier, a ring gear rotationally coupled to a differential meshing planetary compound gear set, and a sun gear coupled to a modal planetary gear set.

[0059] Figure 9 An electric drive 900 is shown with a transmission having a modal planetary gear set 104 and a compound planetary gear set 105 that differentiates meshing planets, as described above with respect to FIG. Figure 1 However, as Figure 9 As shown, planetary gear set 902 is rotationally coupled to input shaft 119. In the illustrated example, planetary gear set 902 is a simple planetary gear set. Planetary gear set 902 includes a fixed ring gear 904, a carrier 906 rotationally coupled to input shaft 119, and a sun gear 908 coupled to an upstream component, such as a motor. Alternatively, planetary gear set 902 may include a fixed carrier 906, a ring gear 904 rotationally coupled to input shaft 119, and a sun gear 908 coupled to an upstream component, such as a motor. However, in other examples, the planetary gear set may be a meshing planet compound planetary gear set with two sets of intermeshing planet gears. Specifically, the structure of a meshing planet compound planetary gear set connected to the input shaft may be similar to the components of a differentiated meshing planet compound planetary gear set 105 with different input and output connections. For example, in the meshing planet compound planetary gear set example, the sun gear may be connected to the upstream component, the carrier may be connected to input shaft 119, and the ring gear may be fixed. Alternatively, in the example of a meshing planet compound planetary gear set, one sun gear may be coupled to the upstream member, one ring gear may be coupled to the input shaft 119 , and the carrier may be fixed.

[0060] Furthermore, it is understandable that Figure 1-9 The differentials described in the can be further combined with springs, clutches or cones, cam ramps, helical gears, worm and spur gears, viscosity, momentum motors, biasing friction and electronic components to create limited slip differentials (LSDs) (e.g., torque sensing limited slip differentials, automatic torque biasing limited slip differentials (ATBs), clutch pack limited slip differentials, bevel gear differentials, double positive differentials, reduction differentials, etc.), torque sensing limited slip differentials), automatic torque biasing (ATB) limited slip differentials, clutch pack limited slip differentials, bevel gear differentials, double positive differentials, reduction differentials, etc. to enhance front and rear axle bias, reduce front and rear axle slip and / or create four-wheel drive functionality, thereby increasing customer appeal.

[0061] It will be appreciated that in certain examples, any of the electric drives described herein may include additional gear sets. For example, in different examples, a planetary gear set (such as a simple planetary gear set or a meshing planet compound planetary gear set) may be disposed between or upstream of the meshing planet compound planetary gear set and the modal planetary gear set. As described herein, a simple planetary gear set refers to a planetary gear set having only one ring gear, one sun gear, and a plurality of planet gears that are located in the same plane as the ring gear and the sun gear. Additionally, as described herein, a meshing planet compound planetary gear set refers to a planetary gear set having one ring gear, one 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.

[0062] Furthermore, in one use case, the differential meshing planetary compound planetary gearset has a 2:1 gear ratio and a 1:1 power output. However, changing the planetary gear ratios can result in front-to-back torque and speed discrepancies. Front-to-back speed discrepancies can be addressed by using different gears in the front and rear differentials. Furthermore, if desired, a differential meshing planetary compound planetary gearset with offset outputs can consistently rotate the meshing planetary gears relative to each other. More generally, the electric transmissions described herein can have a variety of gear ratios, which can be selected based on the end-use design objectives of the vehicle platform. Therefore, the gear ratios shown in the figures are for use cases, and different gear ratios can be used in electric transmissions. Furthermore, the exact location and number of bearings in the electric transmission structures shown in the figures are indicative and exemplary; it is understood that other bearing layouts, types, and numbers can be used in other examples. Furthermore, the electric transmission can utilize one or more transverse electric motors. In some examples, these motors can be connected to the transmission input via hypoid gears or other suitable spiral bevel gears. In these examples, the motors can mesh with the hypoid gears via a mating pinion, with additional gear paths and / or shiftable gears between the motors and the pinion. In various embodiments, the variable speed gears can be mounted on either of the parallel mating shafts. Additionally, additional gear paths can be added to the electric transmission if desired.

[0063] Figure 1-9Configuration examples of the relative positioning of various components are shown. If elements shown in a figure are in direct contact or directly coupled to each other, then, in at least one example, these elements may be referred to as being in direct contact or directly coupled, respectively. Similarly, in at least one example, elements shown as being adjacent or adjacent to each other may be adjacent or adjacent to each other, respectively. For example, elements in face-to-face contact may be referred to as face-to-face contact elements. As another example, in at least one example, elements placed apart from each other, with only space between them and no other elements, may be referred to as being placed apart from each other. As another example, elements displayed above / below, to the sides of, or to the left / right of each other relative to each other may be referred to as such elements. Furthermore, as shown in the figure, in at least one example, the topmost element or element point may be referred to as the "top" of the element, and the bottommost element or element point may be referred to as the "bottom" of the element. As used herein, the terms top / bottom, upper / lower, and above / below may be used to describe the relative positioning of elements in the figure relative to each other, relative to the vertical axis in the figure. Thus, in one example, an element displayed above other elements is positioned vertically above the other elements. As another example, the shapes of elements depicted in the figures may be referred to as having these shapes (e.g., as circular, linear, planar, curved, rounded, chamfered, beveled, or the like). Furthermore, in one example, elements that are coaxial with one another may be referred to as coaxial elements. Furthermore, in at least one example, elements that are shown intersecting one another may be referred to as intersecting elements or intersecting one another. Furthermore, in one example, elements that appear to be within another element or appear to be outside another element may be referred to as intersecting elements. In other examples, elements that are offset from one another may also be referred to as "offset elements."

[0064] Motor and shift control logic / programs, inverters, electronic control units (ECUs), memory storage, throttle, brake, speed and inclination sensors, etc., shift actuators, etc. can further be used in any electric transmission described herein.

[0065] Figure 1-9 A method for operating an electric transmission is provided, wherein the transmission switches between two modes based on vehicle operating conditions. As described above, the electric transmission can be a two-speed transmission or a three-speed transmission. In either configuration, a mode clutch can be operated to shift a mode planetary gear set between two different modes. The method can further selectively lock the differential meshing planetary compound gear set by operating a differential locking clutch in the differential planetary gear set. The method can even further include selectively disconnecting the electric motor and / or the mode planetary gear set by operating a disconnect clutch to enable a towing option or other engine, hybrid, or BEV vehicle function mode, thereby increasing customer appeal.

[0066] The present invention will be further described below. In one aspect, the present invention provides an electric drive system comprising: a motor; a multi-speed transmission rotationally coupled to the motor, rotationally coupled to two output shafts, and comprising: a differential gear set rotationally coupled and coaxially positioned to a mode planetary gear set; and a mode clutch configured to switch between two operating modes. In one example, the mode planetary gear set may be a Ravigneaux gear set rotationally coupled to a differential gear set; the mode clutch is configured to selectively: fix the carrier or ring gear in the Ravigneaux gear set; fix the sun gear in the Ravigneaux gear set; and rotationally couple the carrier or ring gear to the sun gear in the Ravigneaux gear set. Furthermore, in one example, the ring gear or carrier in the mode planetary gear set may be rotationally coupled to the ring gear or carrier in the differential gear set, and the sun gear in the mode planetary gear set is coupled to an upstream component that receives mechanical power from the motor. Furthermore, in one example, the differential may be a differential meshing planetary compound planetary gear set. Furthermore, in one example, the differential meshing planetary compound planetary gear set may include a carrier rotationally coupled to a first output shaft and a sun gear rotationally coupled to a second output shaft. In another example, the electric drive system may further include a differential locking clutch configured to selectively rotationally couple the ring gear in the differential meshing planetary compound planetary gear set to the carrier in the differential meshing planetary compound planetary gear set to lock the rotation of the two output shafts. In another example, the electric drive system may further include a disconnect clutch configured to selectively disconnect the mode planetary gear set from the differential gear set. In another example, the mode planetary gear set is a meshing planetary compound gear set rotationally coupled to the differential; the mode clutch is configured to selectively: fix the carrier or the ring gear in the meshing planetary compound gear set; and rotationally couple the carrier to the ring gear in the meshing planetary compound gear set.

[0067] In another aspect, a method for operating an electric drive system is provided, the method comprising operating a mode clutch to shift between two operating modes; wherein the electric drive system comprises: an electric motor; a multi-speed transmission rotationally coupled to the electric motor, rotationally coupled to two output shafts, and comprising: a differential gear set rotationally coupled and coaxially positioned to a mode planetary gear set; and a 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, fix a carrier or ring gear in the Ravigneaux gear set; in a second mode, fix a sun gear in the Ravigneaux gear set; and in a third mode, rotationally couple the carrier or ring gear to the sun gear in the Ravigneaux gear set; wherein shifting between the two operating modes comprises shifting from the first mode to the second mode, or from the second mode to the third mode. Further, in one example, the mode planetary gear set is a meshing planetary compound planetary gear set, and the mode clutch is configured to: in a first mode, fix the carrier or ring gear in the meshing planetary compound planetary gear set; in a second mode, couple the carrier to the ring gear in the meshing planetary compound planetary gear set; wherein the conversion between the two operating modes includes the first mode to the second mode. In addition, in one example, the differential is a differential meshing planetary compound planetary gear set. In one example, the method may further include operating a differential locking clutch to rotationally couple the ring gear in the differential meshing planetary compound planetary gear set to the carrier in the differential meshing planetary compound planetary gear set to lock the rotation of the two output shafts. In one example, the method may further include operating a disconnect clutch to selectively disconnect the mode planetary gear set from the differential gear set.

[0068] In another aspect, an electric drive system is provided, comprising: an electric motor; a multi-speed transmission rotationally coupled to the electric motor, rotationally coupled to two output shafts, and including: a differential gear set rotationally coupled and coaxially positioned with a modal planetary gear set; and a modal clutch configured to: fix a carrier or ring gear in the modal planetary gear set in a first mode, fix a sun gear in the modal planetary gear set in a second mode, and rotationally couple the carrier or ring gear to the sun gear; fix the carrier or ring gear in the modal planetary gear set in the first mode, ground the sun gear in the modal planetary gear set in the second mode, and rotationally couple the carrier or ring gear to the sun gear in the modal planetary gear set in a third mode; or ground the carrier or ring gear in the modal planetary gear set in the first mode, and rotationally couple the carrier to the ring gear in the second mode. In one example, the modal planetary gear set may be a Ravigneaux gear set. In another example, the modal planetary gear set may be a meshing planet compound planetary gear set. In another example, the differential may be a differential meshing planet compound planetary gear set. Furthermore, in another example, the electric drive system may further include a differential locking clutch configured to selectively couple the ring gear in the differential meshing planetary compound gear set to the carrier in the differential meshing planetary compound gear set to lock the rotation of the two output shafts. In another example, the electric drive system may further include a disconnect clutch configured to selectively disconnect the mode planetary gear set from the differential gear set.

[0069] Furthermore, the electric transmission described herein may also include a control system comprising a controller with a processor and memory storing instructions for executing 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 conjunction with various sensors and actuators. Furthermore, portions of the methods may be physical actions taken in the real world to change the state of a device. The specific routines described herein may represent one or more of any number of processing strategies, such as event-driven, interrupt-driven, multi-tasking, multi-threading, and the like. Therefore, the various actions, operations, and / or functions illustrated may be performed in the sequence illustrated, in parallel, or in some cases omitted. Similarly, the order of processing is not necessarily required to achieve the features and advantages of the examples described herein and is provided for ease of illustration and description. Depending on the specific strategy employed, one or more of the illustrated actions, operations, and / or functions may be performed repeatedly. Furthermore, the described actions, operations, and / or functions may graphically represent code to be programmed into non-transitory memory of a computer-readable storage medium in a system, where the described actions are implemented by executing the instructions in a system comprising various hardware components in conjunction with an electronic controller. If desired, one or more of the method steps described herein may be omitted.

[0070] Although various embodiments have been described above, it should be understood that these embodiments are merely illustrative and not restrictive. It will be understood that the configurations and routines disclosed herein are exemplary in nature and that these specific examples should not be considered restrictive as there can be many variations. For example, the above technology can be applied to power systems that include different types of propulsion sources, including different types of motors, internal combustion engines, and / or transmissions. The technology can be used as a standalone system or in combination with other power transmission systems, for example, but not limited to electric vehicles (such as HEVs, BEVs, etc.), agricultural vehicles or machinery, marine vehicles or machinery, motorcycles, recreational vehicles, and machinery and propulsion systems for road and off-road vehicles, mining vehicles, rail vehicles, manufacturing machinery, industrial machinery, 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. It will be apparent to those familiar with the relevant technology that the disclosed subject matter can be embodied in other specific forms without departing from the spirit of the present subject matter.

[0071] The following claims particularly point out certain combinations and subcombinations regarded as novel and non-obvious. These claims may refer to "an" element or a "first" element or its equivalent. These claims should be understood to include 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 amendment of the present claims or by presentation of new claims in this or a related application. Such claims, whether broader, narrower, equal, or different in scope to the original claims, are also deemed included within the subject matter of the present disclosure.

Claims

1. An electric drive system, characterized in that: include: Motor; a multi-speed transmission rotatably connected to the motor, the multi-speed transmission rotatably connected to two output shafts, and comprising: a differential gear set, the differential gear set being coaxially rotationally coupled and positioned with the modal planetary gear set; as well as A mode clutch is provided, which switches between two operating modes.

2. The electric drive system according to claim 1, wherein The modal planetary gear set is a Ravigneaux gear set rotationally coupled to the differential gear set; and The mode clutch selectively: securing the carrier or ring gear in the Ravigneaux gear set; securing the sun gear in the Ravigneaux gear set; as well as The carrier or ring gear in the Ravigneaux gear set is rotationally coupled to the sun gear.

3. The electric drive system according to claim 2, wherein the ring gear or carrier in the mode planetary gear set is rotationally coupled with the ring gear or carrier in the differential gear set, and the sun gear in the mode planetary gear set is coupled with an upstream component that receives mechanical power from the motor.

4. The electric drive system of claim 1 , wherein the differential gear set is a differential meshing planetary compound gear set.

5. The electric drive system of claim 4, wherein the differential meshing planetary compound planetary gear set includes a carrier rotationally coupled to the first output shaft and a sun gear rotationally coupled to the second output shaft.

6. The electric drive system according to claim 4, characterized in that: A differential lock clutch is further included, which selectively couples the ring gear in the differential meshing planetary compound planetary gear set to the carrier in the differential meshing planetary compound planetary gear set to lock the rotation of the two output shafts.

7. The electric drive system according to claim 2, characterized in that: A transmission disconnect clutch is also included for selectively disconnecting the mode planetary gear set from the differential gear set.

8. The electric drive system according to claim 2, wherein The modal planetary gear set is a meshing planetary compound gear set rotationally coupled to the differential gear set; and The mode clutch selectively: fixing the carrier or ring gear in the meshing planetary compound planetary gear set; and The carrier is rotationally coupled to a ring gear in a compound planetary gear set with meshing planets.

9. The electric drive system of claim 1, wherein the modal planetary gear set is a Ravigneaux gear set.

10. The electric drive system of claim 1, wherein the modal planetary gear set is a meshing planet compound planetary gear set.

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