Electric axle

Abstract

The utility model relates to an electric axle. In one example, an electric axle includes an electric machine removably coupled to a first side of an input shaft via a first mechanical attachment interface, and a differential rotationally coupled to a transmission. The transmission includes an input shaft including a second mechanical interface on a second side opposite the first side, and a clutch mounted on either the intermediate shaft or the input shaft and configured to shift the transmission between at least two gear ratios.

Description

Technical Field

[0001] The present disclosure relates to an electric axle having an input shaft configured to be attached to an electric machine on opposing sides. Background Art

[0002] Electric vehicles use electric drive units to generate motive power and offer an attractive alternative in terms of hydrocarbon emissions to vehicles that rely solely on internal combustion engines for propulsion. Certain vehicles have used electric drive axles because, in some cases, less amount of design work is required to incorporate an electric axle into a vehicle when compared to an electric drive unit spaced farther away from the axle.

[0003] EP3587157B1 to Schneider et al. discloses an electric drive unit including a plurality of motors positioned at the front and rear of the axle shaft. Schneider's electric drive unit also includes a transmission with a planetary gear set for speed reduction.

[0004] WO2022 / 023303A1 to Karlsson et al. discloses a transmission that can be used for both an electric axle and a central drive unit. In Karlsson's transmission, a dog clutch is used to switch between different gears. Karlsson also discloses an electric drive unit architecture with two motors arranged in series.

[0005] The inventors have recognized that there are several problems with both Schneider's electric drive unit and Carlson's transmission. For example, positioning the motors in Schneider's drive unit in front of and behind the axle shaft may be incompatible with certain vehicle platforms, thereby limiting the applicability of the drive unit. In addition, due to the unit's inability to change the gear ratio (or transmission ratio) of the transmission, embodiments of Schneider's single-speed drive unit may exhibit inefficiencies during certain operating conditions. Furthermore, arranging the motors in series limits the ways in which the drive unit can be operated. Utility Model Content

[0006] The inventors have recognized the above problems and developed an electric axle to overcome at least some of these problems. In one example, the electric axle includes a first motor removably connected to a first side of an input shaft via a first mechanical attachment interface. The electric axle also includes a transmission with an input shaft, the input shaft including a second mechanical interface on a second side opposite to the first side. The transmission also includes a clutch mounted on an intermediate shaft or an input shaft and configured to switch the transmission between at least two gear ratios. The electric axle additionally includes a differential rotationally connected to the transmission. In the electric axle, the first motor and the input shaft are arranged coaxially, and the axis of rotation of the side gears in the differential is arranged parallel to the input shaft. Designing the input shaft with two mechanical connection points allows the modularity of the transmission to be improved, thereby increasing the applicability of the drive axle. The second motor can be removably connected to the second mechanical attachment interface of the input shaft. In this way, the architecture of the axle can be adjusted to suit the end user design goals, if desired. Furthermore, positioning the motors at both ends of the input shaft and arranging the motors parallel to the differential allows the end user to achieve increased packaging flexibility without affecting the desired direction of rotation of the transmission gears, oil flow direction, and internal forces on the bearings, if desired.

[0007] It should be understood that the above utility model summary is provided to introduce a selection of concepts further described in the detailed description in a simplified form. It is not meant to identify key or essential features of the claimed subject matter, and the scope of the claimed subject matter is uniquely defined by the claims following the detailed description. In addition, 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

[0008] Figure 1A A first example of an electric axle is shown.

[0009] Figure 1B Shows Figure 1A The e-axle depicted in Figure 1, with the larger capacity motor removed.

[0010] Figure 1C Shows Figure 1A The e-axle depicted in Figure 1, with the smaller capacity motor removed.

[0011] Figure 2A Shown operating in first gear Figure 1A The power path of the electric axle is depicted in Figure 2.

[0012] Figure 2B Shown operating in second gear Figure 1A The power path of the electric axle is depicted in Figure 2.

[0013] Figure 3A shows the operation in the first partial regeneration mode Figure 1A The power path of the electric axle is depicted in Figure 2.

[0014] Figure 3B shows the operation in the second partial regeneration mode Figure 1A The power path of the electric axle is depicted in Figure 2.

[0015] Figure 3C shows the operation in full regeneration mode Figure 1A The power path of the electric axle is depicted in Figure 2.

[0016] Figure 4 A method for operation of an electric axle is shown.

[0017] Figure 5 A timing diagram is shown of an exemplary operating technique of an electric axle. DETAILED DESCRIPTION

[0018] The electric axle described herein has architectural flexibility, which allows the axle to be used in a wider variety of vehicle platforms. In order to achieve the adaptability of the electric axle, the axle includes a transmission with an input shaft, and the input shaft includes a mechanical interface at opposite sides of the shaft to allow one or two motors (e.g., motor-generators) to be coaxially attached to the input shaft. When the electric axle includes two motors, these motors are designed to have variable torque capacity so that the operating mode of the axle can be expanded, improving the efficiency of the axle under a wider range of operating conditions. For example, in a partial regeneration mode (e.g., a single motor regeneration mode), the electric axle can be operated to transfer a portion of the mechanical power generated by one of the motors to the drive wheels, and another portion of the mechanical power is transferred to the other motors for electrical energy generation. In this way, the electric axle can operate efficiently when the axle torque demand is relatively low.

[0019] 1 shows an electric axle 100 that can be included in an electric vehicle (EV) 102. In one example, the electric vehicle can be a fully electric vehicle, although alternative examples are possible, such as a hybrid electric vehicle (HEV) that employs an internal combustion engine for propulsion and / or charging an energy storage device. In addition, the vehicle 102 can be, for example, a light-duty, medium-duty, or heavy-duty vehicle.

[0020] In the illustrated example, the electric axle 100 includes a first electric machine 104 (eg, a first traction motor) and a second electric machine 106 (eg, a second traction motor). However, as explained in more detail herein, the axle may be adapted to operate with only one of the first and second electric machines.

[0021] The first motor 104 and the second motor 106 have varying torque capacities. The torque capacity of a machine may be the peak torque or the continuous torque of the machine. In detail, in the illustrated example, the first motor 104 has a higher torque capacity than the second motor 106. However, the first motor may alternatively have a lower torque capacity than the second motor 106. The use of motors with varying torque capacities allows the electric axle to be used in a wide variety of vehicles with different speed and torque requirements. Therefore, the scope of applicability of the electric axle is expanded. In addition, the use of two motors with varying torque, performance, and efficiency characteristics allows the mode of the axle to be expanded, thereby improving efficiency and thus increasing the vehicle's range.

[0022] Each of the first electric machine 104 and the second electric machine 106 may include a rotor and a stator that electromagnetically interact to generate a rotational output. To vary the torque capacity of the machine, the stator and the rotor may be sized differently. In addition, the first electric machine 104 and the second electric machine 106 may be designed as motor-generators, so that the operating electric machine is used for both driving and regenerative operation.

[0023] In the illustrated example, the first motor 104 and the second motor 106 are electrically coupled to the inverters 107 and 109 via electrical connections (e.g., multi-phase conductors, busbars, combinations thereof, etc.). Thus, in the illustrated example, the motors 104, 106 are alternating current (AC) type motors. In detail, the motors can be multi-phase (e.g., three-phase, six-phase, or nine-phase) AC motors. In a specific use case example, the motors can be three-phase AC motors, which are less expensive and more efficient than single-phase motors. However, in an alternative example, a direct current (DC) motor can be used in an electric axle.

[0024] The inverters 107, 109 can be electrically connected to one or more energy storage devices 115 (e.g., one or more traction batteries, one or more capacitors, one or more fuel cell monomers, combinations thereof, etc.), as shown. However, in alternative configurations, the inverter can be coupled to a different energy storage device. In this way, when the motor is designed as a motor-generator, electrical energy can flow between the inverter and the one or more energy storage devices during driving and regenerative operations. Cables, bus bars, combinations thereof, etc. can be used to form the electrical connections described herein.

[0025] The electric axle 100 includes a transmission 108 (e.g., a multi-speed transmission) that is removably coupled to the electric machines 104, 106 via an input shaft 110. The input and output of the transmission generally represent the power flow that occurs when the vehicle is operating in a driving condition, in which mechanical power is transferred from one or more electric machines to the drive wheels to propel the vehicle in a desired direction (e.g., a forward drive direction or a reverse drive direction). However, it should be understood that during regenerative operation, mechanical power flow occurs in the opposite direction (i.e., from the drive wheels to the (one or more) electric machines).

[0026] The input shaft 110 includes a first mechanical attachment interface 111 on a first side 112 (e.g., a first end) and a second mechanical attachment interface 113 on a second side 114 (e.g., a second end). The first mechanical attachment interface 111 and the second mechanical attachment interface 113 are configured to be removably connected to the first motor 104 and the second motor 106, or vice versa. To achieve the removable attachment function, the mechanical attachment interfaces 111, 113 include splines 116, which cooperate with splines 118 in the rotor shafts 120, 122 of the motors 104, 106. Additionally or alternatively, the input shaft can be connected to the rotor shafts 120, 122 via flanges and attachment devices (e.g., bolts), welding, interference fit, combinations thereof, etc. In one example, the spline can be an involute spline to increase the strength of the interface. However, in other examples, the spline can be a straight spline. The type of spline used in the mechanical interface can be selected based on the expected load on the input shaft.

[0027] The transmission 108 may also include a gear 124 and a gear 126 fixedly coupled to the input shaft 110. For example, the gears 124, 126 may be press-fit, welded, splined, or integrally formed with the input shaft 110. Additionally, the gears 124, 126, as well as other transmission gears described herein, may be helical gears, which provide greater durability than other types of gears, such as straight-cut gears. However, in other examples, straight-cut gears may also be used in the transmission.

[0028] Gear 124 meshes with gear 128, which is idling mounted to intermediate shaft 129. For example, bearing 130 (e.g., needle bearing) can be used to idling mount gear 128 to intermediate shaft 129. The bearings described herein may include an outer race, an inner race, roller elements (e.g., balls, rollers, tapered rollers, needles, etc.). Idling mounting refers to attaching a gear to a shaft so that the gear and shaft can rotate independently. Gear 126 meshes with gear 132, which is additionally idling mounted to intermediate shaft 129. Likewise, bearing 134 (e.g., needle bearing) can be used to achieve the idling mounting function. The use of needle bearings in the transmission allows the compactness of the transmission to be improved.

[0029] The clutch 136 may be mounted on the intermediate shaft 129. The clutch 136 may be configured to selectively engage the gear 128 and the gear 132 to allow mechanical power to be transferred from the engaged gear to the intermediate shaft. The clutch 136 may also be configured to operate in a neutral position, in which neither the gears 128 nor 132 are engaged and thus inhibit mechanical power transfer between the input shaft and the intermediate shaft. For example, during traction operation, it is desirable to place the transmission in a neutral position to reduce back electromotive force (EMF). Thus, in one example, the clutch may be placed in at least three positions (e.g., a first gear position, a second gear position, and a neutral position).

[0030] The clutch 136 is specifically illustrated as a synchronizer that includes a toothed surface 138 on opposite axial sides of component 140. The toothed surface 138 is designed to match the toothed surface 141 on the axial side of gears 128 and 132. The synchronizer is configured to bring the shaft and gear speeds together to enable smoother alignment and meshing of the teeth. The synchronizer may also include a synchronizer ring to enable speed matching functionality. The synchronizer may be electromechanically, hydraulically, and / or pneumatically actuated. For example, a shift fork may be used to actuate the synchronizer. In other examples, the clutch may be a dog clutch, which, however, may reduce the smoothness of the shift.

[0031] In another example, clutch 136 may be mounted on input shaft 110. In such an example, gears 124, 126 may be freewheelingly mounted to input shaft 110, and gears 128, 132 may in turn be fixedly coupled to an intermediate shaft. Further, in such an example, the clutch may be designed to selectively engage the gears on the input shaft and allow mechanical power to be transferred between the two when desired.

[0032] In the illustrated example, the intermediate shaft 129 is positioned between the first motor 104 and the second motor 106 (relative to the x-axis) to improve the compactness of the transmission and allow the mass of the axle to be more centralized. As a result, the vehicle's handling performance can be improved. However, in other examples, the intermediate shaft can be spaced away from the area between the motors, but it may reduce the compactness of the transmission. In addition, as shown, the motors 104, 106 and the input shaft 110 are coaxial with each other, and the axis of rotation of the differential 146 (described in more detail herein) is arranged parallel to the axis of rotation of the motors, and the electric axle achieves the desired compactness and mass balance, which can improve the handling of the vehicle.

[0033] In addition, in the illustrated example, the intermediate shaft 129 includes a gear 142 that is fixedly coupled to the intermediate shaft 129 or integrally formed therewith and meshes with an input gear 144 in a differential 146. However, other transmission architectures have been contemplated. For example, the transmission may include additional shafts and / or clutches. In addition, it will be appreciated that when the transmission is a two-speed transmission with an input shaft and an intermediate shaft, the transmission achieves a desired balance between a gear ratio range and compactness for certain vehicle applications. However, in alternative examples, the transmission may have additional one or more operating gears and, therefore, may include additional clutches and / or shafts. In still further examples, the transmission may be a single-speed transmission.

[0034] The input gear 144 in the differential 146 may be a ring gear, and the differential may also include side gears 148 fixedly coupled to an axle shaft 150 (e.g., a half shaft). The axle shaft, in turn, may be coupled to drive wheels 152. Arrows 154 represent the mechanical connection between the drive wheels and the axle shaft. The axle may also include a hub that allows the drive wheels to rotate.

[0035] Furthermore, in one example, the electric axle 100 may be a beam axle, where the camber angle of the wheels remains substantially constant over the travel of the suspension. In a beam axle embodiment, the axle may thus be coupled to a slave suspension system. Beam axles have increased durability when compared to other types of axles. However, in other examples, the electric axle may not be a beam axle, and thus may be coupled to an independent suspension system.

[0036] The electric axle may also include a control system 190 including a controller 192, such as Figure 1A As shown. The controller 192 may include a microcomputer having components such as a processor 193 (e.g., a microprocessor unit), input / output ports, and an electronic storage medium 194 (e.g., a read-only memory chip, a random access memory, a keep-alive memory, a data bus) for executable programs and calibration values. The storage medium may be programmed with computer-readable data representing instructions that are executable by the processor to perform the methods and control techniques described herein, as well as other variations that are anticipated but not specifically listed. In this way, the control techniques, methods, etc. expanded herein may be stored as instructions in a non-transitory memory.

[0037] The controller 192 may receive various signals from sensors 195 coupled to various areas of the electric axle. For example, the sensors 195 may include a pedal position sensor designed to detect depression of an operator-actuated pedal such as an accelerator pedal and / or a brake pedal, a speed sensor at the transmission output shaft, an energy storage device state of charge (SOC) sensor, a clutch position sensor, and the like. The motor speed may be determined from the magnitude of the power sent by the inverter 107 to the first motor 104. The input device 198 (e.g., an accelerator pedal, a brake pedal, a driving mode selector, a gear selector 199, and combinations thereof, and the like) may also provide input signals indicating the operator's intent for vehicle control. The gear selector 199 may include discrete positions, such as drive and reverse, and first and second gears, which allow the operator to place the transmission in a forward drive mode, a reverse drive mode, a first gear mode, and a second gear mode. It is understood that when the operator places the transmission in a forward drive mode, the transmission may then automatically switch based on the transmission speed, load, and / or torque demand.

[0038] Upon receiving Figure 1A When the controller 192 receives signals from various sensors 195, the controller 192 processes the received signals and uses various actuators 196 of the electric axle components to adjust the components based on the received signals and the instructions stored on the memory of the controller 192. For example, the controller 192 can receive an accelerator pedal signal indicating an operator's request to increase vehicle acceleration. In response, the controller 192 can command the operation of the inverter 107 and / or the inverter 109 to adjust the mechanical power output of the associated motor and increase the power delivered from the motor to the transmission 108. During certain operating conditions, the controller 192 can be designed to send a command to the clutch 136 to perform such a switch, wherein the clutch engages the gear 128 or the gear 132. For example, a control command (such as a first gear, a second gear, or a neutral gear) can be sent to the clutch, and in response to receiving the command, the actuator in the clutch can adjust the clutch based on the command for clutch movement. For example, other controllable components in the vehicle can function in a similar manner in terms of sensor signals, control commands, and actuator adjustments.

[0039] Bearing 156 may be coupled to input shaft 110 and allow it to rotate. Additionally, bearing 158 may be coupled to intermediate shaft 129 and allow it to rotate. Bearings 156, 158 may be positioned axially outward of the gears that reside on the shafts to which the gears are attached. Housing section 160 may extend between motors 104 and 106 to reduce the intrusion of water, debris, etc., into transmission 108, thereby increasing the durability of the axle.

[0040] exist Figure 1A as well as Figure 1B-3BA coordinate system is provided for reference. In one example, the z-axis can be a vertical axis (e.g., parallel to the gravity axis), the x-axis can be a lateral axis (e.g., a horizontal axis), and / or the y-axis can be a longitudinal axis. However, in other examples, these axes can have other orientations. The rotational axes 170, 172, 174, 176, and 178 of the first motor 104, the second motor 106, the input shaft 110, the intermediate shaft 129, and the differential 146 are provided for reference. The rotational axis 178 of the differential specifically corresponds to the rotational axes of both the side gears and the input gear of the differential.

[0041] Figure 1B and 1C Different arrangements of the electric axle 100 are shown, and the first motor 104 and the second motor 106 are removed therefrom, respectively. In this way, the electric axle can be effectively adapted to different vehicle platforms. In both modified electric axle architectures, a cover 180 can be provided in the electric axle to protect the exposed end of the input shaft 110 that is decoupled from the corresponding motor. In addition to Figure 1B and Figure 1C Except for removing the motor from the electric axle architecture, the remaining components in the electric axle are similar to Figure 1A Therefore, redundant descriptions are omitted for the sake of brevity.

[0042] Figure 2A , 2B 3A, 3B and 3C show different mechanical power paths during different operating modes of the electric axle 100. Figure 2A and 2B , which respectively show mechanical power paths 200 and 250 occurring when the electric axle 100 is operated in a driving mode (e.g., forward drive or reverse drive) in a first gear and a second gear. In the first gear, the operating gear ratio is higher than the gear ratio of the second gear. Therefore, the first gear can be used during vehicle lower speed operation, such as starting, and the second gear can be used during vehicle high speed operation. Figure 2A In the first gear drive mode shown, clutch 136 engages gear 128 so that mechanical power is transmitted from gear 128 to intermediate shaft 129 via the clutch. Figure 2B In the illustrated second gear drive mode, clutch 136 engages gear 132 such that mechanical power is transferred by means of the clutch from gear 132 to intermediate shaft 129. The clutch may be shifted between first gear and second gear, and vice versa, in response to operator interaction with the gear selector, or the clutch may be automatically activated in response to changes in torque demand and / or transmission load.

[0043] It will be appreciated that the rotational output of the motor can be reversed to operate the electric axle in a reverse drive mode. Allowing the motor to rotate in the opposite direction allows the space efficiency of the electric axle to be increased when compared to a transmission that employs mechanical reversal. However, in an alternative example, the transmission 108 may include a mechanical reversal component.

[0044] In both power paths 200 and 250, mechanical power flows from the first and second electric machines 104 and 106 to the input shaft 110 via the first and second mechanical attachment interfaces 111 and 113. Furthermore, in both power paths 200 and 250, mechanical power travels from the intermediate shaft 129 to the gear 142, from the gear 142 to the gear 144 in the differential 146, and from the differential to the axle shaft 150.

[0045] exist Figure 2A In the power path 200 shown, mechanical power travels to the intermediate shaft 129 via the gear 124, the gear 128 and the clutch 136. Thus, the axle operates in the first gear mode.

[0046] On the other hand, Figure 2B In the illustrated power path 250, mechanical power travels to the intermediate shaft 129 via the gear 126, the gear 132 and the clutch 136. Thus, the axle operates in the second gear mode.

[0047] Figure 3A and 3B The power paths 300 and 350 are respectively specifically shown when the electric axle 100 operates in different partial regeneration modes (eg, single motor regeneration mode). Specifically, Figure 3A The electric axle is shown operating in a single motor regeneration mode, with the first motor 104 operating in a drive mode and the second motor 106 operating in a regeneration mode. In the power path 300, power is transferred from the first motor 104 to the second motor 106 by means of the input shaft 110 and in particular through the mechanical attachment interfaces 111 and 113. Next, power is transferred from the input shaft 110 to the gear 126, from the gear 126 to the gear 132, and from the gear 132 to the intermediate shaft 129 by means of the clutch 136. Next, power is transferred to the gear 142 and then to the differential 146 via the gear 144. Next, power is transferred from the differential 146 to the axle shaft 150.

[0048] Figure 3BThe electric axle 100 is specifically shown operating in another partial regeneration mode (e.g., a single motor regeneration mode) in which the second electric machine 106 operates in a drive mode and the first electric machine 104 operates in a regeneration mode. In the power path 350, power is transferred from the second electric machine 106 to the first electric machine 104 by means of the input shaft 110 and in particular through the mechanical attachment interfaces 113 and 111. Next, power is transferred from the input shaft 110 to the gear 126, from the gear 126 to the gear 132, and from the gear 132 to the intermediate shaft 129 by means of the clutch 136. Next, power is transferred to the gear 142 and then to the differential 146 via the gear 144. Next, power is transferred from the differential 146 to the axle shaft 150. It will be appreciated that the single motor regeneration mode can also be implemented when the electric axle is operated in first gear, in which the mechanical power travels through the gears 124 and 128. These single motor regeneration modes allow the axle to operate more efficiently under a wider range of operating conditions.

[0049] In addition, the electric axle 100 can be operated in a full regenerative mode in which mechanical power from the drive wheels is transferred to both motors 104 and 106 by means of the transmission 108. In turn, both motors can generate electrical energy. In full regenerative mode, the power path through the transmission can travel through the gear combination 124 and 128, or the gear combination 126 and 132. The full regenerative mode can be configured to additionally have regenerative braking, which relieves the load on the mechanical brakes.

[0050] Figure 3C The electric axle 100 is specifically shown operating in a full regeneration mode (e.g., a dual motor regeneration mode) with the second motor 106 operating in the regeneration mode and the first motor 104 operating in the regeneration mode. The full regeneration mode can be implemented, for example, during deceleration and braking. In the power path 370, power is transferred from the axle shaft 150 to the differential 146. From the input differential, power travels to gear 144. From gear 144, power travels to gear 142 and then to the intermediate shaft 129. Next, power travels through clutch 136 to gear 132 and then to gear 126. From gear 126, power travels through the input shaft 110 to the first motor 104 and the second motor 106, where electrical energy is generated.

[0051] Figure 4 A method 400 for operation of an electric axle is shown. In one example, the method 400 may be performed by Figure 1A100 shown in . In other examples, these methods can be implemented by other suitable electric axles or combinations of electric axles described herein. In addition, as previously described, method 400 can be implemented by a controller including a memory storing instructions for method steps that can be executed by a processor, as previously indicated.

[0052] Method 400 includes determining operating conditions at 402. Operating conditions may include input device position (e.g., gear shift lever position), clutch configuration, transmission input / output speed, motor speed, vehicle speed, vehicle load, ambient temperature, etc. Operating conditions may be determined via sensor input, modeling simulation, lookup tables, combinations thereof, and other suitable techniques.

[0053] Next, at 404, the method includes determining whether the electric axle should be placed in a mode in which both electric motor-generators are operated in a drive mode. This determination may be based on a torque demand on the electric axle, an output speed of the transmission, and / or a transmission load. For example, when there is a torque demand (e.g., torque demand>0) and the transmission speed and / or load is greater than a threshold, the electric axle may be placed in a dual motor drive mode. The transmission speed and / or load threshold may be a threshold that indicates that above this threshold both motors need to be used to meet the torque demand.

[0054] If it is determined that the electric axle should be placed in dual motor drive mode ("yes" at 404), the method moves to 406 where the method includes operating both electric motor-generators in a drive mode. Specifically, the electric axle is operated in a drive mode where both electric motor-generators deliver mechanical power to the drive wheels.

[0055] On the other hand, if it is determined that the electric axle should not be placed in the dual motor mode ("No" at 404), the method moves to 408. At 408, the method includes determining whether the torque demand on the electric axle is greater than a threshold. The threshold allows for a determination of whether to place the electric axle in one of the two single motor regeneration modes of the electric axle.

[0056] If it is determined that the torque demand on the electric axle is not greater than the threshold ("No" at 408), the method moves to 410. At 410, the method includes operating the second motor-generator in a drive mode and operating the first motor-generator in a regenerative mode. Thus, in this single motor regenerative mode, the second motor-generator transmits mechanical power to the drive wheels by means of a transmission, and transmits the mechanical power to the first motor-generator, which converts the mechanical power into electricity. In some cases, the electricity can be transmitted to an energy storage device.

[0057] Next, at 412, the method includes determining whether the electric axle should be operated in a braking or deceleration mode. If it is determined that the electric axle should not be operated in a braking or deceleration mode ("No" at 412), the method returns to 402. Conversely, if it is determined that the electric axle should be operated in a braking or deceleration mode ("Yes" at 412), the method moves to 414. At 414, the method operates the first and second motor-generators in a regenerative mode.

[0058] If it is determined that the torque demand on the electric axle is greater than the threshold ("yes" at 408), the method moves to 416. At 416, the method includes operating the first motor-generator in a drive mode and operating the second motor-generator in a regenerative mode. Thus, in this single motor regenerative mode, the first motor-generator transfers mechanical power to the drive wheels by means of a transmission, and transfers the mechanical power to the second motor-generator, which converts the mechanical power into electrical energy. In some cases, the electrical power can be transferred to an energy storage device. After 416, the method moves to 412, and after 414, the method ends. Method 400 allows the electric axle to operate in a variety of single motor regenerative modes to improve axle adaptability and improve motor efficiency.

[0059] Figure 5 A prophetic timing diagram of an electric axle operating technique for a use case is shown. The operating technique can be implemented in any of the electric axles described herein or in a combination of electric axles. In each figure, time is represented on the abscissa and increases from left to right, but no specific values ​​are indicated.

[0060] The ordinate of graph 502 represents the traction / torque demand at the wheels and increases in the direction of the arrow, but no specific value is indicated. The ordinate of graph 504 indicates the operating state of the first motor-generator (i.e., "drive" and "regeneration"), and the ordinate of graph 506 indicates the operating state of the second motor-generator (i.e., "drive" and "regeneration"). In the drive mode, the motor-generator transmits mechanical power to the drive wheels with the aid of the transmission. In the regeneration mode, the motor-generator receives mechanical power and converts the power into electrical energy.

[0061] From t0 to t1, both motors are operated in the drive mode. As shown, at t1, the traction force drops below the first threshold 508, and the second motor-generator switches from the drive mode to the regeneration mode, while the first motor-generator remains in the drive mode. In this way, the electric axle can be operated in a single motor regeneration mode to improve the efficiency of the axle under a wider range of operating conditions.

[0062] Then at t2, the tractive force reaches the second threshold 510 and the first motor switches from the driving mode to the regeneration mode, while the second motor switches from the regeneration mode to the driving mode. In this way, another single motor regeneration mode is implemented to improve the efficiency of the axle.

[0063] From t2 to t3, the first motor-generator is maintained in the regeneration mode, while the second motor-generator is maintained in the drive mode. In this way, the electric axle can be operated in the single motor regeneration mode. At t3, the traction force drops below the threshold 510, and both motors are operated in the regeneration mode, such as during deceleration and braking.

[0064] The technical effect of the electric axle operation method described herein is to improve the performance and efficiency of the axle by allowing one of the motors to operate in a regenerative mode while the other motor supplies mechanical power to both the drive wheels and the motor operating in the regenerative mode. Additionally, the efficiency of the axle is improved when both motors are operated in the regenerative mode during deceleration and braking.

[0065] Figures 1A-3C An example configuration with relative positioning of various components is shown. If shown as directly contacting or directly connected to each other, such elements can be referred to as directly contacting or directly connected, respectively, at least in one example. Similarly, at least in one example, elements shown as continuous or adjacent to each other can be respectively continuous or adjacent to each other. As an example, components placed as face-shared contact with each other can be referred to as face-shared contact. As another example, in at least one example, elements positioned to be spaced apart from each other with only a spacing space between them and no other components can be referred to as such. As another example, elements shown as above / below each other, on opposite sides of each other, or on the left / right of each other can be referred to as such relative to each other. In addition, as shown in the accompanying drawings, in at least one example, the topmost element or the point position of the element can be referred to as the "top" of the component, and the bottommost element or the point position of the element can be referred to as the "bottom" of the component. As used herein, top / bottom, upper / lower, above / below can be relative to the vertical axis of the accompanying drawings and used to describe the positioning of the elements of the accompanying drawings relative to each other. Therefore, in one example, the element shown as above other elements is vertically positioned above the other elements. As yet another example, the shapes of elements depicted in the accompanying drawings may be referred to as having such shapes (e.g., such as circular, linear, planar, curved, rounded, chamfered, angled, etc.). In addition, in one example, elements that are coaxial with each other may be referred to as such. In addition, in at least one example, elements that are shown as intersecting each other may be referred to as intersecting elements or intersecting each other. Further, in one example, elements that are shown as being within another element or outside another element may be referred to as such. In other examples, elements that are offset from each other may be referred to as such.

[0066] The utility model will be further described in the following paragraphs. In one aspect, an electric axle is provided, comprising: a first motor, the first motor being removably coupled to a first side of an input shaft via a first mechanical attachment interface; a transmission, the transmission comprising: an input shaft, the input shaft comprising a second mechanical interface on a second side opposite to the first side; and a clutch, the clutch being mounted on an intermediate shaft or the input shaft and configured to switch the transmission between at least two gear ratios; and a differential, the differential being rotationally coupled to the transmission; wherein the first motor and the input shaft are coaxially arranged; and wherein the axis of rotation of the side gears in the differential is arranged parallel to the input shaft.

[0067] In another aspect, a method for operating an electric axle is provided, the method comprising: operating a first electric motor-generator to transfer mechanical power to a multi-speed transmission and to a second electric motor-generator; operating the second electric motor-generator in a regenerative mode, wherein the second electric motor-generator generates electrical energy; wherein the first and second motor-generators are arranged coaxially with an input shaft in the multi-speed transmission; and wherein the first and second motor-generators have different torque capacity, performance, and efficiency characteristics. In one example, the method may also include, when the second motor-generator is operated in the regenerative mode, switching the multi-speed transmission between a first gear ratio and a second gear ratio via operating a clutch mounted on an intermediate shaft or an input shaft. In another example, the method may also include switching the multi-speed transmission into neutral via operating a clutch mounted on an intermediate shaft or an input shaft.

[0068] In yet another aspect, an electric axle is provided, comprising: a first traction motor-generator directly and removably coupled to a first end of an input shaft; a second traction motor-generator directly and removably coupled to a second end of the input shaft; a multi-speed transmission comprising: an input shaft; and a clutch mounted on an intermediate shaft and configured to switch the multi-speed transmission between a first gear reduction and a second gear reduction; and a differential having an input gear meshing with a gear on the intermediate shaft; wherein the first traction motor-generator has a higher torque capacity than the second traction motor-generator; and wherein the first traction motor-generator, the second traction motor-generator, and the input shaft are coaxially arranged.

[0069] In any aspect or combination of these aspects, the electric axle can further include a second electric machine removably coupled to the second mechanical interface, wherein the first electric machine and the second electric machine have different torque capacity, performance, and efficiency characteristics.

[0070] In any aspect or combination of these aspects, the first motor and the second motor can be motor-generators; and the electric axle can also include: a controller, which includes instructions that, when executed during a partial regeneration mode, cause the controller to: operate the first motor in a regeneration mode, transfer mechanical power from the second motor to the first motor in the regeneration mode; and operate one of the first motor and the second motor in a drive mode.

[0071] In any aspect or combination of these aspects, the first electric machine can have a higher torque capacity than the second electric machine.

[0072] In any aspect or combination of these aspects, the partial regeneration mode may be a mode in which torque demand on the transmission is below a threshold.

[0073] In any aspect or combination of these aspects, the first mechanical attachment interface and the second mechanical attachment interface can include splines.

[0074] In any aspect or combination of these aspects, the electric axle can further include a controller including instructions that, when executed when the first electric machine is turned off, cause the controller to: shift the transmission into neutral via the clutch.

[0075] In any aspect or combination of these aspects, the transmission can include a gear fixedly coupled to the intermediate shaft and meshing with an input gear in the differential.

[0076] In any aspect or combination of these aspects, the transmission may include first and second gears fixedly coupled to the input shaft and respectively meshing with third and fourth gears idlingly mounted on the intermediate shaft.

[0077] In any aspect or combination of the aspects, the third gear and the fourth gear may be idlingly mounted to the intermediate shaft via needle bearings.

[0078] In any aspect or combination of these aspects, the clutch can be configured to shift the transmission between only two gear ratios.

[0079] In any aspect or combination of the aspects, the clutch can be a synchronizer.

[0080] In any aspect or combination of these aspects, the axis of rotation of the side gears in the differential can be parallel to the input shaft.

[0081] In any aspect or combination of these aspects, the clutch can be a synchronizer and configured to be shifted to a neutral position in which torque transfer between the intermediate shaft and the gear associated with the clutch is inhibited.

[0082] In any aspect or combination of these aspects, the electric axle may also include a controller including instructions that, when executed during a drive mode when a torque demand in the multi-speed transmission is below a threshold, cause the controller to: operate the first traction motor-generator in a regenerative mode in which mechanical power is transferred from the second traction motor-generator to the first traction motor-generator and the first traction motor-generator generates electrical energy.

[0083] In any aspect or combination of these aspects, the controller may also include: instructions that, when executed, cause the controller to: operate the second traction motor-generator in a regenerative mode when the torque demand of the multi-speed transmission is above a threshold during a drive mode, in which mechanical power is transferred from the first traction motor-generator to the second traction motor-generator and the second traction motor-generator generates electrical energy.

[0084] In any aspect or combination of these aspects, the electric axle may also include a controller including instructions that, when executed during braking and / or deceleration, cause the controller to: operate both the first traction motor-generator and the second traction motor-generator in a regenerative mode, in which mechanical power is transferred from the axle shaft to the first and second traction motor-generators to generate electrical energy in the first and second traction motor-generators.

[0085] In any aspect or combination of these aspects, the axle enables increased packaging flexibility when the motor is mounted on either side of the input shaft without affecting the desired rotational direction of the transmission gears, the direction of oil flow, and the internal forces of the upper bearing.

[0086] Although various embodiments have been described above, it should be understood that they are presented as examples rather than limitations. It will be apparent to those skilled in the relevant art that the disclosed subject matter may be implemented in other specific forms without departing from the spirit of the subject matter. Therefore, the above-described embodiments are considered to be illustrative and not restrictive in all respects. Therefore, the configurations and routines disclosed herein are exemplary in nature, and these specific examples should not be considered restrictive, as many variations are possible. For example, the above-described technology can be applied to a powertrain including different types of propulsion sources, including different types of motors and / or internal combustion engines. The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations disclosed herein and other features, functions, and / or characteristics.

[0087] It should be noted that the example control and estimation routines included herein can be used with various electric axles and / or vehicle system configurations. The control methods and routines disclosed herein can be stored in non-transient memory as executable instructions and can be executed by a control system including a controller combined with various sensors, actuators, and other transmissions and / or vehicle hardware combined with an electronic controller. Therefore, the actions, operations and / or functions described can graphically represent the code in the non-transient memory of a computer-readable storage medium that will be programmed into an electric vehicle unit and / or a vehicle system. The various actions, operations and / or functions shown can be performed in the order shown, in parallel, or omitted in some cases. Similarly, the processing order for implementing the features and advantages of the examples described herein is not necessary, but is provided for ease of illustration and description. Depending on the specific strategy used, one or more of the actions, operations and / or functions shown can be repeatedly performed. If desired, one or more method steps described herein can be omitted.

[0088] As used herein, unless otherwise indicated, the term "about" is interpreted to mean plus or minus five percent of the range.

[0089] The appended claims particularly point out certain combinations and subcombinations believed to be novel and non-obvious. These claims may refer to "an" element or a "first" element or the equivalent thereof. Such claims should be understood to include combinations 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 characteristics may be claimed in this or a related application by amendment of the present claims or by presentation of new claims. Such claims, whether broader, narrower, equal, or different in scope to the original claims, are deemed to be included in the subject matter of the present disclosure.

Claims

1. An electric axle, comprising: a first electric machine removably coupled to a first side of the input shaft via a first mechanical attachment interface; A transmission, the transmission comprising: an input shaft comprising a second mechanical interface on a second side opposite the first side; and a clutch mounted on an intermediate shaft or the input shaft and configured to shift the transmission between at least two gear ratios; and a differential rotationally coupled to the transmission; wherein the first motor and the input shaft are coaxially arranged; and Wherein, the rotation axis of the side gear in the differential is arranged parallel to the input shaft.

2. The electric axle according to claim 1, characterized in that: The electric axle also includes a second electric machine removably coupled to the second mechanical interface, wherein the first electric machine and the second electric machine have different torque capacities.

3. The electric axle according to claim 2, characterized in that: The first electric machine and the second electric machine are motor-generators; and The electric axle further comprises: a controller comprising instructions that, when executed during a partial regeneration mode, cause the controller to: operating the first electric machine in a regenerative mode in which mechanical power is transferred from the second electric machine to the first electric machine; and One of the first motor and the second motor is operated in a driving mode.

4. The electric axle according to claim 3, characterized in that: The first electric machine has a higher torque capacity than the second electric machine.

5. The electric axle according to claim 4, characterized in that: The partial regeneration mode is a mode in which torque demand on the transmission is below a threshold.

6. The electric axle according to claim 1, characterized in that: The first mechanical attachment interface and the second mechanical interface include splines.

7. The electric axle according to claim 1, characterized in that: The electric axle further includes a controller including instructions that, when executed when the first electric machine is turned off, cause the controller to: The transmission is shifted into neutral via the clutch.

8. The electric axle according to claim 1, characterized in that: The transmission includes a gear fixedly coupled to the intermediate shaft and meshing with an input gear in the differential.

9. The electric axle according to claim 1, characterized in that: The transmission includes a first gear and a second gear fixedly coupled to the input shaft and respectively meshing with a third gear and a fourth gear idly mounted on the intermediate shaft.

10. The electric axle according to claim 9, characterized in that: The third gear and the fourth gear are idly mounted to the intermediate shaft via needle bearings.

11. The electric axle according to claim 1, characterized in that: The clutch is configured to shift the transmission between only two gear ratios.

12. The electric axle according to claim 1, characterized in that: The clutch is a synchronizer; and / or The rotational axis of the side gears in the differential is parallel to the input shaft.

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