Transmission system

Abstract

Relates to a transmission system. In one example, a transmission system includes a first electric motor rotationally coupled to a first shaft having a first gear fixedly coupled thereto; and a second electric motor rotationally coupled to a second shaft having a second gear fixedly coupled thereto. The transmission system further comprises an intermediate shaft, and a third gear is fixedly connected to the intermediate shaft. A first clutch configured to selectively rotationally couple the first gear and the first shaft; and a second clutch configured to selectively rotationally couple the second gear and the second shaft.

Description

Technical Field

[0001] The present disclosure generally relates to a mechanical transmission system having multiple transmission drive ranges. Background Art

[0002] Some electric vehicles (EVs) use single-ratio transmissions designed to achieve a high top speed while providing high torque at low speeds. However, if the electric motor is sized for high torque, the vehicle's top speed will be low, while if the electric motor is sized for top speed, it may hinder traction performance at low speeds. Therefore, using a single-ratio transmission may result in an oversized electric motor. By using a transmission with two or more speed ratios, the requirements for torque and top speed can be relaxed.

[0003] CN216374144U teaches a dual electric motor drive axle assembly having two shifters arranged on different input shafts and an output shaft coaxial with the differential. In the drive axle assembly, the gear reductions of different speeds formed between the gears on the input shafts and the gears on the output shafts are the same.

[0004] For example, some multi-speed transmissions may experience an undesirable trade-off between torque interruption and drag torque during shift transients, thereby reducing the transmission's shift performance. Other issues related to seamless shifting include the fact that some electric transmissions may oversize the electric motor to compensate for power dissipation during clutch transfer. The powertrain disclosed in CN216374144U uses the same gear reducer at low speeds, which reduces the time span for seamless shifting. Utility Model Content

[0005] To at least partially address the aforementioned issues, a transmission system is provided. In one example, the transmission system includes a first electric motor rotationally coupled to a first shaft, with a first gear idly coupled to the first shaft. The transmission system also includes a second electric motor rotationally connected to a second shaft, with a second gear idly coupled to the second shaft. The transmission system also includes an intermediate shaft fixedly coupled to a third gear. The transmission system also includes a first clutch for selectively rotationally coupling the first gear to the first shaft, and a second clutch for selectively rotationally coupling the second gear to the second shaft. In the transmission system, the third gear meshes with the first gear, and the fourth gear meshes with the second gear. The first and second gears are of the same size. Thus, because the gear reduction ratios of the electric motor and the output shaft are the same, the electric motor can utilize full power at the second speed. Furthermore, if desired, the transmission system can utilize fewer components (e.g., gears, shafts, etc.) while achieving the desired number of gear modes. Therefore, in the disclosed simplified configuration, the use of fewer system components (e.g., gears, etc.) can reduce system space, thereby reducing manufacturing costs, while also improving seamless shifting efficiency and reducing torque interruption.

[0006] In one example, the first and second clutches can be dog clutches. Using dog clutches can improve transmission efficiency compared to wet friction clutches. Furthermore, in this example, synchronizers can be omitted from the transmission system, reducing system complexity. In this example, the first electric motor can match the speed of the first gear before the first clutch engages the first gear, enabling torque transfer between the first shaft and the first gear. This allows gear shifting, if necessary, with little or no power interruption.

[0007] The disclosed transmission system configuration enables seamless shifting without significantly reducing traction by reducing power dissipation in existing systems. In another example, the transmission system may further include a fifth gear fixedly coupled to the first shaft and a sixth gear fixedly coupled to the second shaft. In such an example, the transmission system further includes a seventh gear fixedly coupled to the intermediate shaft and meshing with the fifth gear and the sixth gear, wherein the first clutch is configured to selectively rotationally couple the fifth gear to the first shaft, and the second clutch is configured to selectively rotationally couple the sixth gear to the second shaft. In this example, the fifth gear and the sixth gear are unequal in size. The equal size of the fifth gear and the sixth gear can increase the time span for seamless shifting without compromising shifting performance.

[0008] It should be understood that the above summary is intended to introduce some 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

[0009] Figure 1 A schematic diagram of a vehicle with a transmission and an electric motor is shown.

[0010] Figure 2 An example of a dual electric motor multi-speed drivetrain is shown.

[0011] Figure 3 Shown is Figure 2 A multi-speed transmission system with actuators and sensors omitted.

[0012] Figure 4A A table is displayed, indicating Figure 2 and Figure 3 The different transmission drive ranges in the transmission system described in.

[0013] Figures 4B-4I Shows Figure 4A The power path for the transmission drive range is described in .

[0014] Figure 5 A control method for achieving gear shifting in a transmission system is shown.

[0015] Figure 6 A flow chart showing the implementation of gear shifting in a transmission system.

[0016] Figure 7 A timing diagram showing a control method for executing gear shifts to achieve a transmission drive range is shown. DETAILED DESCRIPTION

[0017] This article describes a transmission system with two or more selectable gears. In one embodiment, the transmission system is a multi-speed transmission comprising multiple shafts connected to dual electric motors and an intermediate shaft. The gear and clutch arrangement enables shifting without sacrificing system efficiency and improves shifting performance by reducing the frequency of perceived judder in the vehicle when needed. Furthermore, a dog clutch or other low-friction clutch enables efficient, seamless shifting without torque interruption.

[0018] like Figure 1FIG. 1 schematically illustrates a powertrain 107 of a vehicle 106 (e.g., an off-highway vehicle). The powertrain 107 can derive propulsion power from one or more electric motors 154 (e.g., traction electric motors) and transmit the power to a transmission 109. Specifically, in one example, the electric motors 154 can be traction electric motors. Thus, the powertrain is included in an electric drive. In one example, the vehicle 106 can be a fully electric vehicle.

[0019] Electric motor 154 may receive electrical energy from energy storage device 158 (eg, a traction battery) to provide torque to wheels 155 and / or 156. Electric motor 154 may also operate as a generator to provide power to charge energy storage device 158, for example, during braking operations.

[0020] The gearbox 109 may include an integrated gearbox. The electric motor 154 may be integrated into the gearbox 109. Alternatively, the electric motor 154 may be coupled to an exterior of the gearbox (e.g., a gearbox housing). The integrated gearbox may include one or more input reduction gear sets. In one example, in a multi-speed gearbox, there are an equal number of drive speeds (e.g., in forward drive and reverse drive operations), thereby improving gearbox performance.

[0021] The controller 112 may constitute part of the control system 114. The control system 114 may receive information from a plurality of sensors 116 and send control signals to a plurality of actuators 181. For example, the sensors 116 may include energy storage device sensors, clutch activation sensors, etc. For another example, the plurality of actuators 181 may include a clutch, etc. The controller 112 may send a signal to the actuator of the clutch to engage or disengage the clutch, thereby coupling or decoupling the power transmission of the electric motor 154 to the rear wheels 155 or the front wheels 156. The controller 112 may receive input data from the sensors 116, process the input data, and trigger the plurality of actuators 181 according to instructions or codes corresponding to one or more routines programmed therein, which are stored in a non-temporary memory. The control system 114 may include information provided herein regarding Figure 2-4I The transmission system is described in more detail. Figure 1 The illustrated control system 114 may be used with any of the transport embodiments described herein.

[0022] Figure 2 A schematic diagram of an exemplary transmission system 200 for a vehicle is shown. It will be appreciated that the transmission system 200 may be included in the vehicle 106, particularly Figure 1 The powertrain 107 is described in detail.

[0023] The transmission system 200 may include an electric motor 222 (e.g., a first electric motor) connected to a first shaft 214. As described herein, the numbering of components such as the first shaft and the second shaft merely indicates the order in which the components are introduced and does not indicate the characteristics of any other components. Therefore, the first shaft 214 may be more generally referred to as shaft 214. Furthermore, in other examples, the component numbering may vary. For example, other parts of this application may use different component numbers based on the order in which the components are introduced.

[0024] Clutch 232 is coaxially arranged with first shaft 214 and is designed to selectively rotationally couple different gears to first shaft 214. Therefore, clutch 232 is a multi-position clutch. In the first position, clutch 232 engages gear 226, rotationally coupling the gear to shaft 214. In the second position, clutch 232 engages gear 240, rotationally coupling the gear to shaft 214. Furthermore, in the neutral position, clutch 232 is disengaged from gears 226 and 240, allowing the gears to rotate independently relative to the shafts. To achieve this engagement, clutch 232 and other clutches may include tooth surfaces that mate with tooth surfaces that mesh with the gears. Specifically, in the illustrated example, clutch 232 is a dog-type clutch, which offers greater efficiency than wet friction clutches.

[0025] Specifically, by using a dog clutch in a transmission, the efficiency loss caused by the high drag torque generated by the presence of a wet friction clutch (such as a dual clutch transmission) can be reduced. Figure 2-4I As described above, seamless gear shifting can be performed with less efficiency loss and a reduced amount of torque interruption (e.g., zero) compared to other transmission systems. In addition, the use of a dog clutch or other low-friction clutch allows the transmission to achieve power shifting without the need for clutch-to-clutch shifting, in which one friction clutch is increasingly engaged while another friction clutch is continuously slipping and eventually disengaging.

[0026] Gear 226 meshes with gear 228, which is rotationally coupled to intermediate shaft 216. Furthermore, gear 240 meshes with gear 242, which is rotationally coupled to intermediate shaft 216. Another gear 243 may be fixedly coupled to intermediate shaft 216. In the illustrated example, gear 243 meshes with gear 245, which is fixedly coupled to shaft 220 (e.g., an output shaft). Shaft 220 may be rotationally coupled to downstream components, such as a drive axle, which will be discussed in greater detail herein.

[0027] Transmission system 200 may include an electric motor 224 (e.g., a second electric motor) coupled to shaft 218. A clutch 236 is coaxially positioned with shaft 218 and is configured to selectively rotationally couple various gears to shaft 218. Thus, clutch 236 is a multi-position clutch. In a first position, clutch 236 engages gear 230, rotationally coupling the gear to shaft 218. In a second position, clutch 236 engages gear 244, rotationally coupling the gear to shaft 218. Furthermore, in a neutral position, clutch 236 is disengaged from gears 230 and 244, allowing the gears to rotate independently relative to the shafts.

[0028] Gear 244 meshes with gear 254 (e.g., an idler gear) rotating on idler shaft 256. Gear 254 meshes with gear 242. Gear 230 can be larger than gear 226. Thus, the gear reduction associated with low-speed drive ranges (such as the first gear drive range) is different. In this example, when gears 226 and 230 are engaged by clutches 232 and 236, respectively, electric motors 222 and 224 will have different angular velocities while rotating in the same direction. Despite the lower vehicle speed at the start of the shift sequence, the difference in first-speed gear ratios increases the time span for seamless shifting. Furthermore, gear 240 can be the same size as gear 244. Therefore, gears 240 and 244 can be the same size. Therefore, because gears 240 and 244 are of equal size, gear 254 allows the direction of rotation of the second electric motor input to be reversed while the electric motors rotate at the same speed. More specifically, to utilize the full power of both electric motors in the second-speed drive range, both electric motors can be connected to the output shaft with the same reduction ratio. In this case, when gears 240 and 244 are engaged with clutches 232 and 236, the angular velocities of electric motors 222 and 224 are the same but of opposite sign. Furthermore, using the aforementioned gear sizes and layout (e.g., gears 240 and 244 are of equal size, with gear 230 being larger than gear 226) can improve the space efficiency of the transmission while achieving the desired shifting performance characteristics. Gears 226 and 230 can be referred to as first speed gears and can be used in a first gear mode when the vehicle is traveling at lower speeds. Additionally, in this example, gears 240 and 244 can be referred to as second speed gears and can be used in a second gear mode when the vehicle is traveling at lower speeds. However, as discussed in more detail herein, in DR21 mode, clutch 232 can engage gear 230 and clutch 236 can engage gear 240.

[0029] In certain embodiments, clutches 232 and 236 can be actuated by actuators 210 and 212, respectively, to achieve different clutch configurations. In one specific example, each actuator can be a hydraulic piston that moves a shift fork. However, other suitable actuator types are contemplated, such as pneumatic actuators, electric motors, mechanical actuators, or combinations thereof. Furthermore, the actuators can be hydraulic actuators, electric actuators, linear actuators, or roller selectors, among others. In one embodiment, transmission system 200 can include a single actuator, such as when operating a barrel cam mechanism.

[0030] Transmission system 200 may also include an intermediate shaft 216, which may be oriented parallel to shaft 214 and shaft 218. In some embodiments, shaft 214, intermediate shaft 216, and shaft 218 may lie in the same plane. Thus, intermediate shaft 216 may be located between shaft 214 and shaft 218. In other embodiments, shaft 214, intermediate shaft 216, and shaft 218 may not lie in the same plane.

[0031] An electric motor 222 (e.g., an electric traction motor) is coupled (e.g., directly coupled) to the shaft 214. Thus, the electric motor 222 can drive the shaft 214 to rotate during operation. Both the electric motor 222 and the electric motor 224 are configured to rotate in opposite directions in different operating modes.

[0032] The transmission system 200 may further include a control system having an electronic control unit (ECU) 202 that executes instructions based on signals from a plurality of sensors and adjusts one or more actuators to adjust various components of the transmission system 200 to achieve shifting between different operating gears. In all embodiments of the transmission system 200, the electric motor 222 and the electric motor 224 are not coaxial. However, the electric motor 222 and the electric motor 224 may be coupled to the same side of the transmission or to opposite sides of the transmission. Figure 2 As shown, electric motor 222 and electric motor 224 are coupled to the same side of the transmission.

[0033] In one embodiment, the transmission housing is schematically represented by a housing 250. In particular, in one example, the transmission housing can accommodate all of the transmission shafts and gears. In other examples, some of the shafts and / or gears can be located outside the transmission housing.

[0034] The various configurations of the transmission system 200 described herein can utilize fewer gears while achieving desired shift performance characteristics compared to other transmission systems. Consequently, the space efficiency of the transmission is improved and manufacturing complexity is reduced.

[0035] As described above, transmission system 200 may include a control system having a plurality of sensors, one or more actuators, and an electronic control unit (ECU) 202. The electronic control unit (ECU) 202 has instructions stored in a memory and executable by at least one processor of the ECU 202 to adjust the one or more actuators based on data received from the plurality of sensors to perform a gear shift. The plurality of sensors may include speed sensors and clutch position sensors. The sensors may include sensors 204, 206, and 208 (e.g., speed sensors) that monitor the speeds of shafts 214, 216, and 218, respectively. In other embodiments, the speed of shaft 214 may be inferred from the speed of electric motor 222, the speed of shaft 218 may be inferred from the speed of electric motor 222, and the speed of intermediate shaft 216 may be inferred from the vehicle speed based on the size of the gear coupled to the intermediate shaft.

[0036] Additionally, the speed of shaft 214 may be provided by a controller area network (CAN) message from the inverter of electric motor 222, and the speed of shaft 218 may be provided by a CAN message from the inverter of electric motor 224. Bearings may be coupled to shafts 214, 216, and 218. More specifically, bearings may be coupled to opposite ends of shafts 214, 216, and 218, respectively.

[0037] Figure 3 The drive system 200 is shown without the actuators and sensors. Figure 2 and Figure 3 Similar component numbers are used in the drawings, and for the sake of brevity, descriptions of redundant components are omitted. However, it is understood that the transmission system 200 can generally include the actuators, sensors and control systems described above.

[0038] Furthermore, electric motors 222 and 224 may be multi-phase traction electric motors that are powered by inverters 300 and 302, respectively. Inverters 300 and 302 may convert direct current to alternating current, and vice versa. Thus, electric motors 222 and 224 may be AC ​​traction electric motors. For example, in one use case, the electric motors and inverters may be three-phase devices. However, electric motors and inverters with more than three phases are also contemplated. The electrical connection between the inverter and the electric motor is represented by wires (e.g., multi-phase wires). However, other suitable electrical connections may also be established between the electric motor and the inverter.

[0039] Inverters 300 and 302 can receive DC power from at least one electrical energy source 304 (e.g., a traction battery, an energy storage device such as a capacitor, or a combination thereof). Arrow 306 indicates the flow of electrical power between the electrical energy source 304 and inverters 300 and 302, while arrow 307 indicates the flow of electrical power between the inverters and electric motors 222 and 224.

[0040] Bearing 310 is connected to gear 226 and shaft 214, allowing gear 226 to be freewheelingly coupled to the shaft. Bearing 312 is connected to gear 240 and shaft 214, allowing gear 226 to be coupled to the shaft at a constant speed. Clutch 232 may include a tooth surface 330 whose profile meshes with the tooth surface on gear 226. Clutch 232 may also include a tooth profile 332 that meshes with the tooth surface on gear 240. Clutch 232 may further include a shift fork interface 334, which is designed to receive input from a shift fork or other suitable actuator. Thus, clutch 232 may be a multi-position dog clutch that engages gears 226 and 240 in different positions. Clutch 232 may also be configured with a neutral position, in which the clutch is not engaged with either gear 226 or 240. Clutch 236 may also be a multi-position clutch with a similar tooth profile configuration. For example, clutch 236 engages gear 230 in one position and engages gear 244 in another position. Clutch 236 can also have a neutral position. In the illustrated example, gear 230 is vertically coupled to shaft 218 via bearing 314, and gear 244 is vertically coupled to shaft 218 via bearing 316.

[0041] The shaft 220 can be rotationally coupled to one or more axle assemblies 320. Each axle assembly 320 can include a differential 322. The differential 322 is rotationally coupled to the drive wheels 324 via the axle. Figure 2 and Figure 3 The relative sizes of the gears described in the examples are drawn to scale. However, it will be appreciated that in other examples, the gears may have different sizes.

[0042] Figure 4A A table 400 is shown illustrating a plurality of transmission drive ranges and Figure 2-3 , and the corresponding states of clutch 232 and clutch 236 are shown in the figure. The corresponding states of the transmission drive ranges and the clutches can be achieved by the control system described herein. The multiple transmission drive ranges include transmission drive range DRNN, transmission drive range DR11, transmission drive range DRN1, transmission drive range DR21, transmission drive range DR2N, transmission drive range DR22, transmission drive range DRN2 and transmission drive range DR1N. The order of the transmission drive ranges is sorted according to the increase in vehicle speed or the decrease in traction. Therefore, the DR11 drive range represents the maximum traction, the DR22 drive range represents the maximum vehicle speed, and the DRNN drive range represents the neutral transmission state. Therefore, as the vehicle speed increases or decreases and / or based on other operating conditions, the transmission system can be converted sequentially between the illustrated drive ranges.

[0043] The transmission drive ranges described above correspond to the operating states of the clutch 232 and the electric motor 222 , and the clutch 236 and the electric motor 224 . Figure 4A The rotational directions of electric motors 222 and 224 are also shown. Specifically, the rotational directions of the electric motors correspond to the forward direction of the vehicle. However, it will be appreciated that when the vehicle is traveling in the reverse direction, the rotational directions of the electric motors are reversed. Thus, for example, when the transmission is operated to propel the vehicle in the reverse direction, the electric motors may rotate counterclockwise in DR11 and DR22.

[0044] In the DRNN drive range, clutches 232 and 236 are both in the neutral position, and electric motors 222 and 224 can rotate in either rotational direction (e.g., clockwise or counterclockwise).

[0045] In the DR11 driving range, clutches 232 and 236 are both engaged with the first speed gear (eg, gears 226 and 230). Additionally, in the DR11 driving range, the electric motor rotates in a clockwise direction.

[0046] In the DRN1 driving range, clutch 232 is in a neutral configuration and clutch 236 is engaged with a first speed gear (eg, gear 230). Additionally, in the DRN1 driving range, the electric motor rotates in a clockwise direction.

[0047] In the DR21 driving range, the clutch 232 is engaged with the second speed gear (such as gear 240), and the clutch 236 is engaged with the first speed gear (such as gear 230). In addition, in the DR21 driving range, the electric motor rotates in a clockwise direction.

[0048] In the DR2N driving range, the clutch 232 is engaged with the second speed gear (eg, gear 240), and the clutch 236 is in the neutral position. In addition, in the DR2N driving range, the electric motor rotates in a clockwise direction.

[0049] In the DR22 driving range, the clutch 232 is engaged with the second speed gear (such as gear 240), and the clutch 236 is engaged with the second speed gear (such as gear 244). In addition, in the DR22 driving range, the rotation direction of the electric motor is reversed.

[0050] Furthermore, in the selectable drive range DRN2, the clutch 232 is in the neutral position and the clutch 236 is engaged with the second speed gear (eg, gear 244). Furthermore, in the DRN2 drive range, the electric motor 224 can rotate in either direction.

[0051] Furthermore, in the selectable drive range DR1N, the clutch 236 is in the neutral position and the clutch 232 is engaged with the first speed gear (eg, gear 226). Furthermore, in the DR1N drive range, the electric motor 222 can rotate in either direction.

[0052] Figure 4B Shown is the transmission system 200 in the DRNN driving range, wherein clutch 232 and clutch 236 are in neutral position.In addition, in the DRNN driving range, electric motors 222 and 224 can rotate in either direction.

[0053] Figure 4C Transmission 200 is shown in the DR11 drive range with clutch 232 and clutch 236 engaged with first speed gear (eg, gears 226 and 230 ), respectively. Figure 4C The mechanical power path 410 within the DR11 drive range is shown.

[0054] Figure 4D Transmission 200 is shown in the DRN1 drive range with clutch 232 in a neutral position and clutch 236 engaged with a first speed gear (eg, gear 230 ). Figure 4D The mechanical power path 412 within the drive range of DRN1 is shown.

[0055] Figure 4E Transmission system 200 is shown in the DR21 drive range with clutch 232 engaged with a second speed gear (eg, gear 240 ) and clutch 236 engaged with a first speed gear (eg, gear 230 ). Figure 4E Represents the mechanical power path 414 within the DR21 drive range.

[0056] Figure 4F Transmission system 200 is shown in the DR2N drive range with clutch 232 engaged with a second speed gear (eg, gear 240 ) and clutch 236 in a neutral position. Figure 4F The mechanical power path 416 within the DR2N drive range is shown.

[0057] Figure 4G Transmission 200 is shown in the DR22 drive range with clutch 232 engaged with a second speed gear (eg, gear 240 ) and clutch 236 engaged with a second speed gear (eg, gear 245 ). Figure 4G The mechanical power path 418 within the drive range of DR22 is shown.

[0058] Figure 4H Transmission system 200 is shown in the DRN2 drive range with clutch 232 in a neutral position and clutch 236 engaged with a second speed gear (eg, gear 244 ). Figure 4H The mechanical power path 420 within the drive range of DRN2 is shown.

[0059] Figure 4I The transmission system 200 is shown in the DR1N drive range with the clutch 236 in the neutral position and the clutch 232 engaged with the first speed gear (eg, gear 226 ). Figure 4I The mechanical power path 422 within the DR1N drive range is shown in FIG.

[0060] Figure 5 A method 500 is shown for controlling the operating modes of a first electric motor and a second electric motor to achieve multiple transmission drive ranges. The method 500 may be performed by Figure 1-4I The method 500 may be implemented by any of the transmission systems or combinations of transmission systems shown in FIG. 1 , but it should be understood that similar methods may be used for other systems without departing from the scope of the present disclosure. The instructions for executing the method 500 may be provided by an electronic control unit (ECU) (e.g., Figure 2 ECU202 in the controller) according to the instructions stored in the controller memory and in combination with the system sensors (as described above Figure 2 The ECU can use the system's actuators to adjust the transmission clutch according to the method described below.

[0061] At 502, method 500 includes providing power to the electric motors from a power source while operating in a low-speed drive range. The power source may independently provide power to the first and second electric motors. In this manner, current may be provided to the first and second electric motors to power the motors. While power is being provided to the first and second electric motors, the transmission system may operate in the low-speed drive range.

[0062] At 506, method 500 includes adjusting at least one gear by engaging and disengaging a clutch according to the desired gear shift to achieve a transitional transmission drive range. The transitional transmission drive range may include one of the transmission drive ranges in which at least one of the two electric motors is in a neutral state (e.g., as described above with respect to the transmission drive range). Figure 4A To enable a transitional transmission drive range, at least one of the gear ratios corresponding to the first electric motor or the gear ratios corresponding to the second electric motor may be engaged or disengaged, depending on whether the gear is initially disengaged or engaged.

[0063] In a first example, when the second electric motor is not in a neutral state, the gear ratio of the first electric motor may initially be engaged, indicating that the first electric motor is operating at the first speed or the second speed of the first electric motor as described herein. By disengaging the gears in the first electric motor gear ratio, the first electric motor enters a neutral state, and the entire system enters a transitional transmission drive range. In a second example, when the first electric motor is not in a neutral state, one of the gears in the second electric motor gear ratio may initially be engaged, indicating that the second electric motor is operating at the first speed or the second speed of the second electric motor as described herein. By disengaging the gears in the second electric motor gear ratio, the second electric motor enters a neutral state, and the entire system enters a transitional transmission drive range.

[0064] At 508, method 500 includes placing or maintaining the first and second electric motors in at least one of a synchronous mode or a traction mode depending on the desired gear shift while operating in the transitional transmission drive range. Synchronous mode is an operating mode for speed control, and traction mode is an operating mode for torque control. With respect to traction mode, traction mode ensures that a desired torque is generated during operation. Specifically, the load of the first or second electric motor is maintained or adjusted so that the first and second electric motors generate a desired torque, or adjustments are made to compensate for a decrease in torque of one of the first or second electric motors. When electric motor synchronization is used in the transmission, the synchronizer clutch may be omitted to simplify the transmission structure. However, in other examples, the dog clutch described herein may include a synchronizer.

[0065] With respect to the synchronization mode, the speed of each electric motor may be slowed down or accelerated until the speed difference between the desired gear and each shaft coupled to the electric motor is within a predetermined speed threshold. To achieve a speed within the predetermined speed threshold, the speed of each electric motor (e.g., one of the first electric motor or the second electric motor) may be slowed down or accelerated. The gear speed is determined by the vehicle speed and cannot be controlled during gear shifting. Therefore, synchronization is achieved by adjusting the speed of the respective electric motors rather than by mechanical synchronizers. However, other embodiments of the present disclosure may also include mechanical synchronizers to improve synchronization efficiency.

[0066] In certain embodiments, the first and second electric motors can operate in traction mode for the majority of their operating time and enter synchronous mode when a gear shift is performed to change the speed of each motor. Returning to the first example described above, where the gears in the first electric motor's gear ratio may initially be engaged, the gear shift causes the first electric motor to enter a neutral state and a transitional transmission drive range. After the gear shift is performed, the first electric motor can enter synchronous mode, while the second electric motor, which has not undergone a gear shift, can remain operating in traction mode. Moving to a second example, where the gears in the second electric motor's gear ratio may initially be disengaged, the gear shift causes the second electric motor to begin operating at the second electric motor's first speed within the transitional transmission drive range. Similarly, after the gear shift is performed, the second electric motor can enter synchronous mode, while the first electric motor, which has not undergone a gear shift, can remain operating in traction mode.

[0067] At 510 , method 500 includes adjusting engagement and disengagement of at least one gear via a clutch based on a desired gear shift to achieve a higher speed drive range. To achieve the higher speed drive range, at least one of the gears of the first electric motor or the gears of the second electric motor may be engaged or disengaged based on whether the gears were initially disengaged or engaged.

[0068] Returning to the first example above, where the gears in the first electric motor's gear ratio may initially be engaged, a shift causes the first electric motor to enter a neutral state and transition the transmission's drive range. After entering synchronous mode, subsequent shifts can be made by engaging gears to enable the first or second speed of the first electric motor, depending on whether the first electric motor was initially operating in the second or first speed. This allows for a higher speed drive range to be achieved through the shift.

[0069] In a second example, a gear in the second electric motor's gear ratio may initially be engaged, with the shift causing the second electric motor to enter a neutral state and transition the transmission's drive range. After entering synchronous mode, subsequent shifts can be made by engaging gears to enable the second electric motor's first or second speed, depending on whether the second electric motor was initially operating in the second or first speed. This allows for a higher speed drive range to be achieved through the shift. After the first or second electric motor completes all shift operations, the first or second electric motor can exit synchronous mode and return to traction mode.

[0070] Looking back at the first example described above, the gear ratio of the second electric motor's gear engagement and disengagement remains constant throughout the gear shift. Therefore, during the gear shift, the current supplied to the second electric motor increases to compensate for the torque reduction of the first electric motor.

[0071] At 514, method 500 includes providing power to the first and second electric motors while operating in the higher speed drive range. Power can be independently provided to the first and second electric motors via a power source. Thus, current can be provided to the first and second electric motors to power the motors while operating in the higher speed drive range. Method 500 ends.

[0072] It is understood that other embodiments of the method 500 may deviate from the above without departing from the scope of the present disclosure. For example, the method may implement a shift from a higher speed range to a lower speed range. In addition, Figure 4A Shifting between the different transmission drive ranges shown may be accomplished via a method of transmission system operation.

[0073] Figure 6 A flow chart 600 is shown for implementing shifts to achieve the drive ranges: DRNN, DRN1, DR21, DR2N, DR22, and DRN2. Figure 6 As shown, the boxes with solid lines represent the neutral transmission drive range and the non-transitional transmission drive range, the boxes with dashed lines represent the transitional transmission drive range, and the boxes with dotted lines represent the optional transmission drive range. The transmission system can operate the above transmission drive ranges, including the transmission drive range DRNN, transmission drive range DR11, transmission drive range DRN1, transmission drive range DR21, transmission drive range DR2N, transmission drive range DR22, and transmission drive range DRN2 described herein. Gear shifting can be based on Figure 2-4I The system and method are performed.

[0074] According to a series of gear shifts, the following transmission drive ranges, including the transmission drive range DR11, the transmission drive range DR21, and the transmission drive range DR22, can be considered as non-transitional drive ranges. Similarly, the following plurality of transmission drive ranges, including the transmission drive range DRN1, the transmission drive range DR2N, and the transmission drive range DRN2, can be considered as transitional transmission drive ranges.

[0075] At block 602, a transmission system, such as that described above, Figure 2 Transmission system 200 is in transmission drive range DR11. Shift 616a enables the transmission system to achieve a first transitional transmission drive range, such as transmission drive range DRN1, at case 604. As shown, shift 616b returns the transmission system from transmission drive range DRN1 to transmission drive range DR11. Thus, during shift 616a, transmission drive range DR11 can be considered a low-speed drive range.

[0076] In transmission 606, the transmission system enters transmission drive range DR21 via shift 618a. As shown, shift 618b returns the transmission system from transmission drive range DR21 back to transitional transmission drive range DRN1. In transmission 608, the transmission system enters transitional transmission drive range DR2N via shift 620a. As shown, shift 620b returns the transmission system from transitional transmission drive range DR2N back to transmission drive range DR21.

[0077] At box 610, the transmission enters transmission drive range DR22 via shift 622a. As shown, shift 622b returns the transmission from transmission drive range DR22 to transitional transmission drive range DR2N. At box 612, the transmission can optionally enter a degraded electric motor management mode, in which the first electric motor can be disconnected, as described herein. Thus, the transmission can enter an optional transmission drive range (e.g., transmission drive range DRN2) via shift 624a. As shown, shift 624b returns the transmission from transmission drive range DRN2 to transmission drive range DR22. In other examples, the second electric motor can be disconnected when it is determined that the second electric motor has been degraded.

[0078] In certain embodiments, the transmission system can be brought into a neutral transmission drive range DRNN by shifting 626a on case 614. Thus, the transmission system may initially operate in a different transitional transmission drive range, with shifting 626a causing the transmission system to operate in the neutral transmission drive range DRNN. For example, a different transitional transmission drive range can be enabled by shifting 626b. Thus, under certain operating conditions, such as during vehicle towing, the transmission system may initially operate in a neutral transmission range (e.g., transmission drive range DRNN).

[0079] Please see Figure 7 , a timing diagram 700 is shown in which the control method described herein is applied to a first electric motor and a second electric motor to achieve a transmission drive range through a shifting operation. At time t0, the vehicle initially operates in a lower speed drive range DR11, wherein the first electric motor operates at a first speed in traction mode (e.g., represented by a solid line) and the second electric motor operates at a second speed in traction mode (e.g., represented by a solid line). Furthermore, the first and second electric motors are powered by a power source. At t1, the vehicle continues to operate in transmission drive range DR11 and traction mode. As the first electric motor performs a series of shifts, the first electric motor is unloaded to zero torque, and the second electric motor is loaded to compensate for the power drop of the first electric motor.

[0080] At time t2, when the first corresponding gear of the first electric motor is disengaged, the required power is supplied to the second electric motor, placing the first electric motor in a neutral state and achieving the transitional transmission drive range DRN1. This allows the torque of the second electric motor to increase to compensate for the decrease in torque of the first electric motor, thereby preventing a torque drop. If the second electric motor can meet the torque demand, a seamless shift is achieved. However, if the second electric motor cannot meet the torque demand, the torque drop may hinder a seamless shift. At time t3, because electric synchronization compensates for the speed variation of the first electric motor in the transitional transmission drive range DRN1, the required power continues to be supplied to the second electric motor. As a result, the first electric motor operates in synchronization mode (shown by the dashed line), while the second electric motor operates in traction mode (shown by the solid line). The speed of the first electric motor is decelerated to a certain value until a predetermined speed threshold between the two is reached.

[0081] When the second corresponding gear of the first electric motor engages, the required power continues to be supplied to the second electric motor, causing the first electric motor to operate at its second speed, thereby achieving the higher-speed drive range DR21 at time t4. Furthermore, the first electric motor continues to operate in synchronous mode, while the second electric motor continues to operate in traction mode. At time t5, the load on the first and second electric motors is again shared, reducing the load on the first electric motor and increasing the load on the second electric motor in the higher-speed drive range DR21 in traction mode. At time t6, the first and second electric motors are powered in the higher-speed drive range DR21 in traction mode.

[0082] The transmission system described herein enables seamless gear shifting based on driving conditions and electric motor characteristics. Furthermore, the number of electric motors in the system can be reduced, if necessary, thereby improving system space efficiency. Furthermore, the transmission system described herein allows a single electric motor to continuously provide and maintain the required power and tractive effort. Consequently, the duration of shift transients can be increased, if necessary, enabling slow and smooth gear shifts. Furthermore, the transmission system described herein can omit a wet friction clutch, if necessary, thereby improving transmission efficiency. Furthermore, the transmission system described herein can display a symmetrical number of gear ratios in forward / reverse drive modes. Furthermore, the use of two electric motors enables the system to operate in a mode that disables one of the electric motors if performance degradation of the electric motor or corresponding inverter is determined. Furthermore, in one example, if thermal degradation of one electric motor occurs, the vehicle's performance degradation can be mitigated by temporarily peaking the other electric motor.

[0083] Figure 1-3 and Figures 4A-4IExample configurations of various elements positioned relative to each other are shown. If the 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 referred to as being adjacent or adjacent to each other, respectively. For example, elements that are in face-to-face contact may be referred to as being in face-to-face contact. Another example is that, in at least one example, elements that are separated from each other, with only space between them and no other elements, may be referred to as being separated from each other. For another example, elements that are shown above / below each other, to the sides of each other, 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, up / down, up / down, and up / down may be used to describe the positioning of elements in a figure relative to each other, relative to the vertical axis in the figure. Thus, in one example, an element that is shown above other elements is positioned vertically above the other elements. For another example, the shapes of elements depicted in the figures may be referred to as having those shapes (e.g., as circular, straight, flat, curved, rounded, chamfered, beveled, or the like). Furthermore, in at least one example, elements depicted as intersecting one another may be referred to as intersecting elements or as intersecting one another. Furthermore, in one example, elements that appear within or outside another element may also be referred to as intersecting elements.

[0084] The present invention is further described below. In one aspect, the present invention provides a transmission system comprising a first electric motor rotatably coupled to a shaft, a first gear being idly coupled to the shaft; a second electric motor rotatably coupled to a second shaft, a second gear being idly coupled to the shaft; an intermediate shaft fixedly coupled to a third gear; a first clutch configured to selectively rotatably couple the first gear to the first shaft; and a second clutch configured to selectively rotatably couple the second gear to the second shaft, wherein the third gear meshes with the first gear, the fourth gear meshes with the second gear, and the first gear and the second gear are of equal size.

[0085] In another aspect, a method for operating a transmission system is provided, the method comprising operating a first electric motor and a second electric motor in opposite rotational directions while a first clutch and a second clutch engage a first gear and a second gear, wherein the transmission system comprises a first electric motor rotationally coupled to a first shaft, a first gear idlingly coupled to the shaft, a second electric motor rotationally coupled to a second shaft, a second gear idlingly coupled to the shaft, an intermediate shaft having a third gear fixedly connected thereto, a first clutch configured to selectively rotationally couple the first gear and the first shaft, a second clutch configured to selectively rotationally couple the second gear and the second shaft, wherein the third gear is engaged with the first gear, the fourth gear is engaged with the second gear, and the first gear and the second gear are of the same size.

[0086] In another aspect, an electric transmission system is provided, the system including a first electric motor driving a first shaft, the first shaft having a first gear idly coupled thereto; a second electric motor driving a second shaft, the second shaft having a second gear idly coupled thereto; an intermediate shaft having a third gear fixedly connected thereto; a fifth gear idly coupled to the first shaft; a sixth gear idly coupled to the second shaft; a seventh gear fixedly connected to the intermediate shaft and meshing with the fifth gear and the sixth gear, a first dog clutch configured to selectively rotationally couple the first gear and the first shaft and the fifth gear and the first shaft in different configurations, and a second dog clutch configured to selectively rotationally couple the second gear and the second shaft and the sixth gear and the second shaft in different configurations, wherein the third gear meshes with the first gear and the second gear.

[0087] In any aspect or combination of the above aspects, the transmission system may further include a fifth gear idlingly coupled to the first shaft, a sixth gear idlingly coupled to the second shaft, and a seventh gear fixedly coupled to the intermediate shaft and meshing with the fifth gear and the sixth gear, wherein the first clutch is configured to selectively rotationally couple the fifth gear and the first shaft, and the second clutch is configured to selectively rotationally couple the sixth gear and the second shaft, wherein the fifth gear and the sixth gear are unequal in size.

[0088] In any aspect or combination of the above aspects, the first clutch and the second clutch can be dog clutches.

[0089] In any aspect or combination of the above aspects, the transmission system may further include a controller including instructions that, when executed, cause the controller to operate the first clutch to rotationally couple the first gear and the first shaft, operate the second clutch to rotationally couple the second gear and the second shaft, and operate the first electric motor and the second electric motor at the same speed and in opposite rotational directions.

[0090] In any aspect or combination of the above aspects, the transmission system may further include a controller including instructions that, when executed, cause the controller to adjust a speed of the first electric motor based on a speed of the first gear during a shift transient when the first clutch is in a neutral configuration, and to operate the first clutch to rotationally couple the first gear and the first shaft when a speed difference between the first shaft and the first gear is below a threshold.

[0091] In any or all of the above aspects, the transmission system can have a symmetrical number of transmission ratios in the forward and reverse directions.

[0092] In the above aspects or combinations of the aspects, the transmission system may further include a final drive that rotationally couples the intermediate shaft and the output shaft.

[0093] In any or all of the above aspects, the transmission system may further include a differential directly coupled to the output shaft.

[0094] In any or all of the above aspects, the differential may be positioned coaxially with the output shaft.

[0095] In any or all of the above aspects, the first electric motor and the second electric motor may be parallel to each other.

[0096] In any or all of the above aspects, the first shaft, the second shaft, the intermediate shaft, the first electric motor, and the second electric motor may be parallel to one another.

[0097] In any or all of the above aspects, the transmission system may not include a synchronizer.

[0098] In any aspect or combination of the above aspects, the method for operating a transmission system may further include: when the first clutch is in a neutral configuration, adjusting the speed of the first electric motor according to the speed of the first gear; when the speed difference between the first shaft and the first gear is lower than a threshold, operating the first clutch to rotationally couple the first gear and the first shaft.

[0099] In any one or combination of the above aspects, the method for operating a transmission system may further include, in response to determining degradation of the first electric motor, transitioning the first clutch to a neutral configuration and ceasing operation of the first electric motor.

[0100] In any one or combination of the above aspects, the electric drivetrain may further include a controller including instructions that, when executed, cause the controller to, in the second gear mode, operate the first dog clutch to rotationally couple the first gear and the first shaft, operate the second dog clutch to rotationally couple the second gear and the second shaft, and operate the first electric motor and the second electric motor at the same speed and in opposite rotational directions.

[0101] In any one or combination of the above aspects, the electric drivetrain may further include a controller including instructions that, when executed, cause the controller to, in the first gear mode, operate the first dog clutch to rotationally couple the fifth gear and the first shaft, operate the second dog clutch to rotationally couple the sixth gear and the second shaft, and operate the first electric motor and the second electric motor in the same rotational direction.

[0102] In any aspect or combination of the above aspects, the electric drivetrain may further include a controller including instructions that, when executed, cause the controller to match speeds of the first shaft and the first gear or the fifth gear during a shift transient when the first dog clutch is in a neutral configuration.

[0103] In any or all of the above aspects, the first shaft, the intermediate shaft, and the second shaft may be arranged parallel to each other.

[0104] Although various embodiments have been described above, it should be understood that these embodiments are merely illustrative and not restrictive. It will be apparent to those skilled in the art that the disclosed subject matter may be embodied in other specific forms without departing from the spirit of the subject matter. Therefore, the above embodiments should be considered in all respects as illustrative and not restrictive.

[0105] The technical effect of the method of operating the system described herein is that gear shifting can be performed seamlessly and efficiently, thereby improving the gear shifting performance of the system by utilizing a system with fewer gears and other mechanical components.

[0106] Note that the control and estimation routine examples included herein can be used with various powertrain and / or vehicle system configurations. The control methods and routines disclosed herein can be stored as executable instructions in non-transitory memory and executed by a control system, including a controller, in conjunction with various sensors, actuators, and other vehicle hardware. Furthermore, portions of the methods may be physical actions taken in the real world to change device states. 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 order shown, in parallel, or omitted in some cases. 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 the non-transitory memory of a computer-readable storage medium in a vehicle control 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.

[0107] It will be appreciated that the configurations and routines disclosed herein are exemplary in nature, and that these specific examples are not limiting, as many variations are possible. For example, the above-described techniques can be applied to power systems that include different types of propulsion sources, including different types of electric motors and transmissions. The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations, and other features, functions, and / or properties disclosed herein.

[0108] 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. A transmission system, characterized in that: The transmission system comprises: a first electric motor, the first electric motor being rotatably connected to a first shaft, a first gear being idlingly coupled to the first shaft; a second electric motor, the second electric motor being rotatably connected to a second shaft, to which a second gear is idly coupled; an intermediate shaft, on which the third gear is fixedly connected; a first clutch configured to selectively rotationally couple the first gear and the first shaft; and a second clutch configured to selectively rotationally couple the second gear and the second shaft; wherein the third gear is meshed with the first gear, and the fourth gear is meshed with the second gear; and The first gear and the second gear have the same size.

2. The transmission system according to claim 1, characterized in that Also includes: a fifth gear idly coupled to the first shaft; a sixth gear idly coupled to the second shaft; as well as a seventh gear fixedly coupled to the intermediate shaft and meshing with the fifth gear and the sixth gear, wherein the first clutch is configured to selectively rotationally couple the fifth gear and the first shaft, and the second clutch is configured to selectively rotationally couple the sixth gear and the second shaft; Wherein, the sizes of the fifth gear and the sixth gear are not equal.

3. The transmission system according to claim 1, characterized in that The first clutch and the second clutch are dog clutches.

4. The transmission system according to claim 1, characterized in that Also included is a controller, wherein the controller includes instructions that, when executed, cause the controller to: operating the first clutch to rotationally couple the first gear and the first shaft; operating the second clutch to rotationally couple the second gear and the second shaft; and The first electric motor and the second electric motor are operated at the same speed and in opposite directions of rotation.

5. The transmission system according to claim 1, characterized in that Also included is a controller including instructions that, when executed, during a shift transient when the first clutch is in a neutral configuration, cause the controller to: adjusting the speed of the first electric motor according to the speed of the first gear; and When a speed difference between the first shaft and the first gear is lower than a threshold, the first clutch is operated to rotationally couple the first gear and the first shaft.

6. The transmission system according to claim 1, characterized in that The transmission system has a symmetrical number of gear ratios in the forward and reverse directions.

7. The transmission system according to claim 1, characterized in that The invention also includes a main reducer which rotationally couples the intermediate shaft and the output shaft.

8. The transmission system according to claim 7, characterized in that: Also included is a differential directly connected to the output shaft.

9. The transmission system according to claim 8, characterized in that: The differential is located coaxially with the output shaft.

10. The transmission system according to claim 1, wherein: The first electric motor and the second electric motor are parallel to each other.

11. The transmission system according to claim 10, characterized in that: The first shaft, the second shaft, the intermediate shaft, the first electric motor and the second electric motor are parallel to each other.

12. The transmission system according to claim 1, wherein: Synchronizer not included.

13. The transmission system according to claim 3, characterized in that Also included is a controller comprising instructions for causing the controller to perform the following operations when executed in the second gear mode: operating the first clutch to rotationally couple the first gear and the first shaft; operating the second clutch to rotationally couple the second gear and the second shaft; and The first and second electric motors are operated at the same speed and in opposite directions of rotation.

14. The transmission system according to claim 2, wherein: Also included is a controller including instructions that, when executed, in a first gear mode: operating the first clutch to rotationally couple the fifth gear and the first shaft; operating the second clutch to rotationally couple the sixth gear and the second shaft; and The first electric motor and the second electric motor are operated in the same rotational direction.

15. The transmission system according to claim 3, characterized in that Also included is a controller comprising instructions that, when executed during a shift transient, cause the controller to: When the first clutch is in a neutral configuration, the speeds of the first shaft and first gear or fifth gear are matched.

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