Multi-speed gearbox

Abstract

The utility model relates to a multi-speed gearbox. In one example, a multi-speed transmission includes a planetary assembly having a first gear set rotationally coupled to a second gear set. The multi-speed transmission also includes a first clutch configured to selectively couple the first sun gear of the first gear set to the input shaft, the input shaft configured to be rotatably coupled to the electric machine, and a second clutch configured to selectively couple the first sun gear of the second gear set to the output shaft.

Description

Technical Field

[0001] The present disclosure relates to a multi-speed transmission having a planetary assembly including a first gear set and a second gear set. Background Art

[0002] Multi-speed transmissions have been used in electrified powertrains in an attempt to improve motor efficiency and traction performance of the transmission. Multi-speed transmissions can be beneficial in heavy vehicles and particularly in vehicle platforms where smoother gear shifting is desired, such as in passenger cars. Due to the capabilities of the electric motor, particularly in its powerband, an electric transmission is able to have a greater degree of gear separation than a transmission that receives motive power input from an internal combustion engine.

[0003] US 2020 / 0149612 A1 to Rippelmeyer teaches a transmission with a compound planetary gear set. In the transmission of Rippelmeyer, a clutch allows power to be transmitted from the input to the sun gear in each stage of the compound planetary gear set.

[0004] The inventors have recognized that there are several disadvantages to the transmission of Riepelmeier, as well as other previous transmissions. The compound planetary gear sets and associated clutches can be space inefficient, complex, and expensive to manufacture. However, other transmissions with fewer operating gears exhibit a wider ratio spread, which can cause or exacerbate torque interruption during shift transients. In detail, limitations of certain clutches and their material construction may require relatively smaller gear stages to achieve smoother shifts. Further, other transmissions that employ planetary gear sets, particularly those that employ Ravigneaux-type gear sets, can exhibit high ring gear speeds. High ring gear speeds increase the likelihood of gear degradation. Utility Model Content

[0005] The inventor has developed a multi-speed transmission to at least partially solve the above problems. In one example, the multi-speed transmission includes a planetary assembly having a first gear set rotatably coupled to a second gear set. The multi-speed transmission also includes a first clutch configured to selectively couple a first sun gear of the first gear set to an input shaft configured to be rotatably coupled to a motor. The multi-speed transmission even includes a second clutch configured to selectively couple the first sun gear of the second gear set to an output shaft. In this way, the transmission is able to achieve a relatively small spread of gear ratios in a compact package.

[0006] In one example, the multi-speed transmission also includes a third clutch configured to selectively couple the input shaft to the second sun gear in the second gear set. In such an example, the multi-speed transmission may also include a fourth clutch configured to selectively couple the planet carrier of the second gear set to the output shaft. Using four clutches in such an architecture allows the transmission to achieve at least four gear stages in a space-saving package.

[0007] In another example, the first planet carrier in the first gear set can be directly fixedly coupled to the second planet carrier in the second gear set. In addition, in one example, the ring gear of the first gear set or the second gear set can be grounded. Designing the gears in the planetary assembly in this way allows the compactness of the gearbox to be further improved.

[0008] 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

[0009] Figure 1A A multi-speed transmission in a vehicle powertrain is shown.

[0010] Figure 1B Shows Figure 1A Table showing the clutch configuration in different operating gears of the gearbox shown.

[0011] Figure 1C A table with exemplary gear ratio equations is shown.

[0012] Figure 2A , 2B , 2C and 2D show the Figure 1A The power path of a multi-speed transmission is shown in a differential operating gear stage.

[0013] Figure 3 Another example of a multi-speed transmission is shown.

[0014] Figure 4A and 4B The gear shifting method in the transmission is shown. DETAILED DESCRIPTION

[0015] A multi-speed gearbox with a planetary assembly and a plurality of clutches, which can achieve tighter conversion between digital transmission ratios in a compact package compared to other gearboxes such as gearboxes using Ravigneaux gear sets. In addition, the multi-speed gearbox can achieve these characteristics while maintaining a common rotation direction of each gear (if desired, avoiding the traction motor from reversing to switch between drive gears). In addition, in order to achieve these features, the planetary assembly includes a first gear set that is rotationally coupled to a second gear set, a one-way clutch that selectively connects an input shaft and a sun gear in the first gear set, and another clutch that selectively connects the sun gear in the second gear set to an output shaft. In one example, the first gear set and the second gear set can be referred to as a LuaE gear set assembly. In addition, the planet carriers in the first gear set and the second gear set can be directly fixedly coupled to each other. In this way, the planet carrier in the second gear set can act as an input and output in one of the gear stages. Therefore, if desired, the multi-speed gearbox can achieve the desired packaging efficiency and transmission ratio separation.

[0016] Figure 1A A multi-speed transmission 100 that may be included in the system 102 is shown. The multi-speed transmission 100 (e.g., a multi-speed electric transmission) may be included in a powertrain 104 of a vehicle 106. In the example shown, the powertrain 104 is an electric powertrain. The electric powertrain may specifically be an all-electric powertrain or a hybrid electric powertrain. An all-electric powertrain may be used as compared to a hybrid electric powertrain because of its reduced complexity and therefore reduced potential component degradation points.

[0017] In a hybrid electric powertrain example, an internal combustion engine may be used to recharge energy storage device 112 and / or drive one of the vehicle axles. Additionally, in an alternative example, the powertrain may be a powertrain having an internal combustion engine that produces motive power.

[0018] In one example, the vehicle 106 may be, for example, a medium or heavy vehicle. In such an example, the vehicle may be a passenger car. However, in other examples, the vehicle may be another suitable type of vehicle, such as a light vehicle and / or a non-passenger vehicle.

[0019] The powertrain 104 includes an electric machine 108 (e.g., a traction motor). In the example shown, the electric machine 108 is electrically coupled to an inverter 110 via an electrical connection (e.g., a multi-phase wire, a bus bar, a combination thereof, etc.). Thus, in the example shown, the electric machine 108 is an alternating current (AC) type motor. In detail, the electric machine can be a multi-phase (e.g., a three-phase, six-phase, or nine-phase) AC motor. In one specific use case example, the electric machine can be a three-phase AC motor, which is less expensive and more efficient than a single-phase type motor. However, in an alternative example, a direct current (DC) traction motor can be used in the electric powertrain 104.

[0020] The inverter 110 may be electrically connected to an energy storage device 112 (e.g., one or more traction batteries, one or more capacitors, one or more fuel cell cells, combinations thereof, etc.). Thus, when the motor is designed as a motor generator, electrical energy may flow between the inverter and the energy storage device during both driving and regenerative operations. Arrows 114 represent the transfer of electrical energy between the motor 108, the inverter 110, and the energy storage device 112.

[0021] The electric powertrain 104 may also include one or more drive axle assemblies 116 that are mechanically coupled to one or more output shafts 118 that may be included in the multi-speed gearbox 100. In one example, the drive axle assemblies may be specifically front and rear drive axle assemblies. The drive axle assemblies may include a differential, an axle shaft (e.g., a half shaft) coupled to the associated differential, a drive wheel coupled to the axle shaft, etc. The drive wheel may be mounted on a wheel hub and may contact a drive surface when the vehicle is in operation.

[0022] The electric machine 108 may include components such as a rotor and a stator that electromagnetically interact during operation to generate motive force. Additionally, in one example, the motor may be a motor-generator designed to generate electrical energy during regenerative operation.

[0023] The multi-speed transmission 100 may include an input shaft 120 that is mechanically coupled (e.g., directly mechanically coupled) to a rotor shaft in the motor 108. In one example, the input shaft 120 may be directly coupled to the rotor shaft via a spline or other suitable mechanical connection. However, in other examples, gears, shafts, chains, combinations thereof, etc. may be used to establish a connection between the transmission and the motor. The input and output of the transmission generally represent the power flow that occurs when the powertrain is operating under a driving condition, wherein mechanical power is transmitted from the traction motor to the drive wheels to propel the vehicle in a desired direction (e.g., a forward drive direction or a rearward drive direction). However, it should be understood that during regenerative operation, the mechanical power flow occurs in the opposite direction (i.e., from the drive wheels to the traction motor).

[0024] The multi-speed transmission 100 also includes a planetary assembly 122 having a first gear set 124 rotatably coupled to a second gear set 126. In the example shown, the first gear set may be characterized as a simple stepped planetary gear set, while the second gear set may be a simple planetary gear set. Further, in one specific example, the planetary assembly may be referred to as a LuaE gear set.

[0025] Furthermore, in the example shown, the planet carrier 128 in the first gear set 124 is directly rotationally coupled to the planet carrier 130 in the second gear set 126. However, in other examples, the first gear set and the second gear set may be rotationally coupled using other gears. The first gear set 124 also includes planet gears 132 and a sun gear 134 rotatably mounted on the planet carrier 128. The sun gear 134 meshes with the planet gears 132. Furthermore, in the example shown, the first gear set 124 does not include a ring gear, which increases the compactness of the gearbox and reduces the complexity of the gearbox. However, as described herein with respect to Figure 3 By extension, the first gear set may include a ring gear.

[0026] In the example shown, the second gear set 126 includes a sun gear 136, planet gears 138 rotatably mounted on the planet carrier 130, and a ring gear 140. In the example shown, the ring gear 140 is permanently grounded. Permanently grounding the ring gear allows the gearbox to achieve at least four gear ratios with reasonable spread between gears. In addition, in one use case example, by permanently grounding the ring gear 140, the gear speeds in the gearbox are reduced compared to a Ravigneaux gear set in which the ring gear speed would exceed 200 meters per second (m / s). These high ring gear speeds result in very high circumferential forces, which require strict balancing targets. In contrast, the gearbox described herein allows the balancing targets in the planetary assembly to be relaxed, if desired, thereby simplifying gearbox manufacturing.

[0027] In an alternative example, the first gear set 124 may include a ring gear permanently grounded and meshing with the planet gears 132, and the ring gear 140 may be omitted from the second gear set 126. Thus, in this alternative example, the gearbox would have different numerical ratios, but retain similar kinematics.

[0028] Additionally, shaft 142 is coupled to sun gear 136. Shaft 142 and planet carrier 130 allow for a changing connection to output shaft 118, which is expanded upon herein. Output shaft 118 may be coupled to one or more transaxle assemblies 116, as previously described.

[0029] The multi-speed transmission 100 also includes a plurality of clutches that allow the transmission to operate in a plurality of gear stages. For purposes of illustration, the multi-speed transmission 100 is specifically described as a four-speed transmission having four discrete gear stages. However, in alternative examples, the transmission may include additional stages, as described herein with respect to Figure 3 The expansion may include fewer gear stages, such as two or three stages.

[0030] In the illustrated example, the first clutch 144 in the multi-speed transmission 100 is designed to couple the sun gear 134 to the input shaft 120 when engaged, and to allow the input shaft 120 and the sun gear 134 to rotate independently when disengaged. In one example, the first clutch 144 can be a one-way clutch (e.g., a sprag clutch). It should be understood that the one-way clutch rotates freely when rotating in one direction, and transmits torque through it when rotating in the opposite direction. In the sprag clutch example, the clutch may include an inner race fixedly coupled to the input shaft 120 or an extension of the input shaft, an outer race fixedly coupled to the sun gear 134, and a plurality of sprags between the inner race and the outer race. Other sprag clutches described herein may include similar configurations with respect to races and sprags. In other examples, the first clutch 144 may be a dog clutch, a friction clutch (e.g., a wet friction clutch), or a synchronizer, however, in some cases, the synchronizer may increase the complexity and size of the transmission. For example, the dog clutches, synchronizers, and friction clutches described herein may be actively controlled via electromechanical, hydraulic, and / or pneumatic actuators.

[0031] In addition, in the illustrated example, the second clutch 146 in the multi-speed transmission 100 is designed to rotationally couple the sun gear 136 to the output shaft 118 when engaged, and inhibit torque transfer between the sun gear 136 and the output shaft 118 when disengaged. The shaft 142 can be specifically coupled to the sun gear 136 and the second clutch 146. In one example, the second clutch 146 can be a one-way clutch. However, in other examples, the second clutch can be a dog clutch, a friction clutch (e.g., a wet friction clutch), or a synchronizer.

[0032] Further, in the illustrated example, the third clutch 148 allows torque transfer between the input shaft 120 and the sun gear 136 in the second gear set 126 when engaged, and conversely inhibits torque transfer between the input shaft 120 and the sun gear 136 when disengaged. Since the third clutch experiences higher speeds than other clutches during transmission operation, the third clutch 148 can be a friction clutch (e.g., a wet friction clutch). When the third clutch is a friction clutch, the clutch may include a first set of plates coupled to the input shaft 120 and a second set of plates coupled to the sun gear 136. A planet carrier (e.g., a drum) may hold the plates and the sets of plates may be staggered. During engagement, a piston or other suitable actuator may cause frictional engagement of the sets of plates. Other friction clutches described herein may have similar configurations with respect to plates and actuators.

[0033] In addition, in the example shown, the fourth clutch 150 is capable of enabling torque transfer between the planetary carrier 130 and the output shaft 118 in the second gear set 126 when engaged, and inhibiting torque transfer therebetween when disengaged. In one example, the fourth clutch 150 can be a friction clutch (e.g., a wet friction clutch). However, in other examples, the third clutch and / or the fourth clutch can be a dog clutch. Further, in other examples, all clutches can be friction clutches or all clutches can be dog clutches. Even further in other examples, a portion of the clutch can be a dog clutch and a portion of the clutch can be a friction clutch. When the gearbox uses two one-way clutches and two friction clutches, the gearbox can achieve a desired balance between space efficiency and shifting performance.

[0034] The powertrain 104 may also include a control system 190 having 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.

[0035] The controller 192 may receive various signals from sensors 195 coupled to various areas of the powertrain 104. 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, etc. The motor speed may be determined from the amount of power sent by the inverter to the motor 108. The input device 198 (e.g., an accelerator pedal, a brake pedal, a drive mode selector, a gear selector 199, a combination of these, etc.) may further provide input signals indicating the operator's intent for vehicle control. The gear selector 199 may include discrete positions, such as forward drive and reverse and first and second gears, which allow the operator to place the transmission in forward drive mode, reverse drive mode, first gear mode, second gear mode, third gear mode, and fourth gear mode. It should be understood that when the operator places the transmission in forward drive mode, the transmission may then automatically trigger a power switch based on the transmission speed and load.

[0036] Upon receiving Figure 1A When the controller 192 receives signals from various sensors 195 in the multi-speed transmission 100, the controller 192 processes the received signals and, based on the received signals and instructions stored on the memory of the controller 192, uses various actuators 196 of the powertrain and / or transmission components to adjust the components. For example, the controller 192 may receive an accelerator pedal signal indicating an operator's request to increase vehicle acceleration. In response, the controller 192 may command the operation of the inverter 110 to adjust the mechanical power output of the motor and increase the power delivered from the motor 108 to the multi-speed transmission 100. During certain operating conditions, the controller 192 may be designed to send commands to the friction clutches 148 and 150 to perform some of the engagement and disengagement switching of the clutches. For example, a control command may be sent to the clutch 148, and in response to receiving the command, an actuator in the clutch or an actuator coupled to the clutch may adjust the clutch based on the command for the clutch to engage or disengage. For example, other controllable components in the vehicle may function in a similar manner in terms of sensor signals, control commands, and actuator adjustments.

[0037] Figure 1 and Figure 2A , Figure 2B , Figure 2C , Figure 2D and Figure 3 A coordinate system is provided for reference in . 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.

[0038] The motor 108 may be designed to rotate the rotor shaft in opposite directions corresponding to forward drive and reverse drive. Thus, in such an example, the multi-speed transmission 100 may be designed in one example to operate with an equal number of forward and reverse drive gear modes. However, in an alternative example, the transmission may have an asymmetric number of selectable forward and reverse gear ratios.

[0039] In addition, the motor 108 can rotate in a common direction during a drive mode (e.g., forward or reverse drive mode) while the multi-speed transmission operates in each gear stage and in transitions between gear stages. In this way, motor reversal during shift transients can be avoided, thereby simplifying shifting and reducing torque interruption.

[0040] In addition, Figure 1A The multi-speed transmission 100 of the architecture shown in FIG. 1 may not be able to produce a ratio that results in an increase in speed. Therefore, the multi-speed transmission may be suitable for electric powertrains, many of which do not require a transmission ratio that increases speed.

[0041] Figure 1BA table 160 is shown indicating the configuration of the clutches 144, 146, 148, 150 in the first, second, third, and fourth gears. In the first gear, the first clutch 144 and the fourth clutch 150 are engaged, while the second clutch 146 and the third clutch 148 are disengaged. In the second gear, the third clutch 148 and the fourth clutch 150 are engaged, while the first clutch 144 and the second clutch 146 are disengaged. In the third gear, the first clutch 144 and the second clutch 146 are engaged, while the third clutch 148 and the fourth clutch 150 are disengaged. In the fourth gear, the first clutch 144 and the fourth clutch 150 are disengaged, while the second clutch 146 and the third clutch 148 are engaged.

[0042] As about Figure 1A As discussed, the first clutch 144 and the second clutch 146 may be one-way clutches, while the third clutch 148 and the fourth clutch 150 may be friction clutches. Thus, in order to enter different operating gears, the third clutch and the fourth clutch may be actively controlled, and the first clutch and the second clutch may be passively engaged and disengaged based on the active control of the third clutch and the fourth clutch. However, as previously discussed, in other examples, the first clutch and / or the second clutch may be actively controlled clutches, such as friction clutches or dog clutches.

[0043] Figure 1C A table 170 with equations for calculating the gear ratio in each discrete operating gear is shown. However, it should be understood that the equations may vary for transmissions with varying architectures. The size of each gear in the planetary assembly may be selected based on a variety of factors, such as traction motor powerband, traction motor size, traction motor peak continuous power, transmission performance goals, vehicle weight, etc. In a specific use case example, the sun gear 134 may have 53 teeth, the sun gear 136 may have 71 teeth, the planetary gears 132 may have 47 teeth, the planetary gears 138 may have 31 teeth, and the ring gear 140 may have 133 teeth. In such a use case example, the first gear ratio is 4.805, the second gear ratio is 2.873, the third gear ratio is 1.672, and the fourth gear ratio is 1.000. In this way, a reasonable spread between each of the four gears is achieved. As a result, the transmission achieves smoother shifting, thereby enhancing the performance of the transmission. However, it should be understood that in alternative examples, the transmission gears may have different numbers of teeth.

[0044] Figure 2A , 2B2C and 2D show the mechanical power paths 200, 202, 204, 206 that appear in the multi-speed transmission 100 in the first operating gear, the second operating gear, the third operating gear and the fourth operating gear, respectively. Figure 2A , Figure 2B , Figure 2C and Figure 2D In each of the inverters 110, the power is transmitted to Figure 1A The electric machine 108 is shown, and the traction motor generates mechanical power and inputs that power into the input shaft 120. However, as previously discussed, in other embodiments, the inverter may be omitted from the powertrain.

[0045] Figure 2A The mechanical power path 200 shown in FIG. 1 travels from the input shaft 120 via the first clutch 144 to the sun gear 134 , from the sun gear 134 to the planet gears 132 , from the planet gears 132 to the planet carrier 128 , from the planet carrier 128 to the planet carrier 130 , and from the planet carrier 130 to the output shaft 118 via the fourth clutch 150 .

[0046] Figure 2B The mechanical power path 202 shown in FIG. 1 travels from the input shaft 120 via the third clutch 148 to the sun gear 136 , from the sun gear 136 to the planet gears 138 , from the planet gears 138 to the planet carrier 130 , and from the planet carrier 130 via the fourth clutch 150 to the output shaft 118 .

[0047] Figure 2C The mechanical power path 202 shown in the figure travels from the input shaft 120 via the first clutch 144 to the sun gear 134, from the sun gear 134 to the planetary gears 132, from the planetary gears 132 to the planetary carrier 128, from the planetary carrier 128 to the planetary carrier 130, from the planetary carrier 130 to the planetary gears 138, from the planetary gears 138 to the sun gear 136, and from the sun gear 136 to the output shaft 118 via the second clutch 146.

[0048] Figure 2D The mechanical power path 206 shown in FIG. 1 is from the input shaft 120 via the third clutch 148 to the sun gear 136 , and from the sun gear 136 via the second clutch 146 to the output shaft 118 .

[0049] Figure 3 Another example of a multi-speed gearbox 300 is shown. The gearbox also includes a planetary assembly 302 having a first gear set 304 and a second gear set 306. Thus, the multi-speed gearbox 300 includes a planetary assembly 302 having a first gear set 304 and a second gear set 306. Figure 1A The illustrated multi-speed transmission 100 has overlapping components, and redundant descriptions are omitted for brevity. Figure 3 The illustrated transmission 300 includes a brake 308 that selectively grounds the ring gear 310 meshing with the planetary gears 312 in the first gear set 304 and another brake 314 that selectively grounds the ring gear 316 meshing with the planetary gears 318 in the second gear set 306. Incorporating brakes into the transmission enables the number of operating gears in the transmission to be increased if desired. Specifically, if desired, Figure 3 The gearbox 300 shown in FIG. 1 can be operated in six gears.

[0050] Figure 4A and 4B Methods 402 and 450 for operating a multi-speed transmission are shown, respectively. Specifically, Figure 4A An upshift method for shifting (eg, power shifting) to third gear is shown, while Figure 4B Conversely, a downshift technique for shifting (e.g., power shifting) to third gear is shown. In one example, methods 400 and 450 may be performed by Figure 1A The methods 400 and 450 may be implemented by a controller including a memory storing instructions of the method steps executable by a processor, as previously indicated. In detail, the multi-speed transmission operating method is implemented in a transmission in which the third clutch and the fourth clutch are actively controlled clutches such as friction clutches, dog clutches, or synchronizers, and the first clutch and the second clutch are one-way clutches. However, as previously discussed, in other examples, the transmission may present other clutch architectures.

[0051] Figure 4A The method 400 shown in FIG. 4 includes determining operating conditions at 402. The operating conditions may include the position of an input device (e.g., the position of a shift lever), clutch configuration, accelerator pedal position, transmission input / output speed, motor speed, vehicle speed, vehicle load, ambient temperature, etc. The operating conditions may be determined via sensor input, modeling, lookup tables, and / or other suitable techniques.

[0052] Next at 404, the method includes determining whether an upshift between second gear and third gear should be implemented in the transmission. In one example, this determination can be performed automatically in response to the vehicle speed exceeding a threshold and / or the vehicle load falling below a threshold. In other examples, an operator interaction with a gear selector can initiate an upshift.

[0053] If it is determined that an upshift should not occur ("NO" at 404), the method moves to 406 where it includes maintaining the current transmission operating strategy. For example, the transmission may remain in its current operating gear ratio (eg, second gear).

[0054] Conversely, if it is determined that an upshift should occur ("YES" at 404), the method moves to 408 where the method includes executing an upshift from second gear to third gear.

[0055] Executing an upshift includes steps 410-412. Steps 410-412 may occur at overlapping times and in some cases simultaneously. At 410, the method includes disengaging the third clutch, and at 412, the method includes disengaging the fourth clutch. The clutch engagement may be initiated via a hydraulic actuator having a piston that receives pressurized fluid (e.g., oil) from a hydraulic system. However, in other examples, the friction clutch may be electromechanically actuated, for example, via a solenoid. In response to the disengagement set of the third clutch and the fourth clutch, the first clutch and the second clutch transition from a disengaged configuration to an engaged configuration. After 412, the method ends.

[0056] Figure 4B The method 450 shown in FIG. 4 shows a downshift strategy. At 452, the method includes determining operating conditions. Figure 4A Step 402 is shown to determine the operating conditions in a similar manner.

[0057] Next, method 450 includes step 454, where the method includes determining whether a downshift from the fourth operating gear to the third operating gear should be implemented. In one example, the determination can be performed automatically in response to the vehicle speed decreasing below a threshold and / or the vehicle load increasing above a threshold. In other examples, operator interaction with the gear selector can initiate a power downshift.

[0058] If it is determined that a power downshift should not occur ("NO" at 454), the method moves to 456 where it includes maintaining the current transmission operating strategy. For example, the transmission may remain in its current operating gear ratio (eg, fourth gear ratio).

[0059] Conversely, if it is determined that a power downshift should occur ("yes" at 454), the method moves to 458, where the method includes executing a power downshift from the fourth operating gear to the third operating gear. Executing the downshift includes steps 460-462. At 460, the method includes disengaging the third clutch, and at 462, the method includes maintaining the fourth clutch disengaged. In response to the disengagement of the third clutch, the first clutch transitions from a disengaged configuration to an engaged configuration. After 462, the method ends. Figure 4A and Figure 4B The gearbox is allowed to shift smoothly to the third operating gear, in which the planet carrier in the second gear set serves as both the output and input of the gear set.

[0060] It should be understood that other upshifts and downshifts between other operating gears in the multi-speed transmission can occur in a similar manner, and the clutch control for other gear changes can be controlled by Figure 1B 160 is defined as shown in FIG. In addition, it should be understood that the traction motors coupled to the multi-speed gearbox can rotate in a common direction when the gearbox is operated in each gear. In other words, the rotational direction of the motor can be maintained during the gear shift transient, thereby simplifying the gear shift operation and reducing the possibility of torque interruption.

[0061] The technical effect of the multi-speed transmission operating method described herein is to enhance shifting performance by using a transmission having a desired ratio split and packaging efficiency. As a result, the transmission and corresponding operating method can be used in a wider range of vehicle platforms.

[0062] Figure 1 Figure 2A , Figure 2B , Figure 2C , Figure 2D and Figure 3An example configuration with relative positions 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 shape of the elements depicted in the accompanying drawings may be referred to as having such a shape (e.g., such as circular, linear, planar, curved, blunt, 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 with each other may be referred to as intersecting elements or intersecting with 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. Further, elements that are coaxial or parallel to another element may be referred to as such. Further, the axis about which the component rotates may be referred to as the axis of rotation.

[0063] The utility model will be further described in the following paragraphs. In one aspect, a multi-speed transmission is provided, which includes a planetary assembly, the planetary assembly including: a first gear set, which is rotationally coupled to a second gear set; a first clutch, which is configured to selectively couple a first sun gear of the first gear set to an input shaft, the input shaft being configured to be rotatably coupled to a motor; and a second clutch, which is configured to selectively couple a second sun gear of the second gear set to an output shaft.

[0064] In another aspect, a method for operating a multi-speed transmission is provided, the method comprising shifting between two gear stages of a group of at least four stages in the multi-speed transmission via engagement or maintaining engagement of each of a first clutch and a second clutch, wherein the multi-speed transmission comprises: a planetary assembly comprising: a first gear set rotationally coupled to a second gear set; a first clutch configured to selectively couple a first sun gear of the first gear set to an input shaft; and a second clutch configured to selectively couple a second sun gear of the second gear set to an output shaft.

[0065] On the other hand, a multi-speed electric transmission is provided, which includes a planetary assembly, the planetary assembly comprising: a first gear set, which includes a first planet carrier directly connected to a second planet carrier of a second gear set; a first clutch, which is configured to selectively connect the first sun gear of the first gear set to an input shaft; a second clutch, which is configured to selectively connect the second sun gear of the second gear set to an output shaft; a third clutch, which is configured to selectively connect the input shaft to the second sun gear in the second gear set; and a fourth clutch, which is configured to selectively connect the planet carrier of the second gear set to the output shaft.

[0066] In any of these aspects or combinations of these aspects, the second clutch can be a one-way clutch.

[0067] In any of these aspects or combinations of these aspects, the multi-speed transmission can further include a third clutch configured to selectively couple the input shaft to the second sun gear in the second gear set.

[0068] In any of these aspects or combinations of these aspects, the third clutch can be a friction clutch.

[0069] In any of these aspects or combinations of these aspects, the multi-speed transmission may further include a fourth clutch configured to selectively couple the planet carrier of the second gear set to the output shaft.

[0070] In any of these aspects or combinations of these aspects, the first gear set or the second gear set may not include a ring gear.

[0071] In any of these aspects or combinations of these aspects, the first planet carrier in the first gear set can be directly fixedly coupled to the second planet carrier in the second gear set.

[0072] In any of these aspects or combinations of these aspects, the ring gear of the second gear set or the first gear set can be grounded.

[0073] In any of these aspects or combinations of these aspects, the planetary assembly may include a first ring gear of a first gear set and a second ring gear of a second gear set, and the multi-speed transmission may include a first brake configured to selectively ground the first ring gear and a second brake designed to ground the second ring gear.

[0074] In any of these aspects or combinations of these aspects, the multi-speed transmission can be configured to operate in at least four different gear stages, and the multi-speed transmission can also include a controller comprising: instructions that, when executed during forward drive, cause the controller to: cause the motor to rotate in a common direction in the first gear stage, the second gear stage, the third gear stage, and the fourth gear stage.

[0075] In any of these aspects or combinations of these aspects, shifting between two gear stages can include disengaging or maintaining disengagement of each of a third clutch and a fourth clutch in the multi-speed transmission; the third clutch can be configured to selectively connect the input shaft to the second sun gear of the second gear set; and the fourth clutch can be configured to selectively connect the planetary carrier of the second gear set to the output shaft.

[0076] In any of these aspects or combinations of these aspects, shifting between the two gear stages may occur in a drive mode in which a traction motor coupled to the multi-speed gearbox rotates in one direction.

[0077] In any of these aspects or combinations of these aspects, the third clutch can be a friction clutch and the fourth clutch can be a dog clutch or a friction clutch.

[0078] In any of these aspects or combinations of these aspects, the first clutch and the second clutch can be one-way clutches.

[0079] In any of these aspects or combinations of these aspects, the ring gear of the second gear set can be permanently grounded and the first gear set does not include a ring gear; or, the ring gear of the first gear set can be permanently grounded and the second gear set does not include a ring gear.

[0080] In any of these aspects or combinations of these aspects, the multi-speed transmission may further include a brake configured to selectively ground the first ring gear of the first gear set and the second ring gear of the second gear set.

[0081] In any of these aspects or combinations of these aspects, the shaft can be directly coupled to the second sun gear and the second clutch.

[0082] In any of these aspects or combinations of these aspects, the multi-speed electric transmission can be configured to shift between only four discrete gear stages.

[0083] In another formulation, a multi-speed transmission is provided that includes a multi-stage planetary assembly having a first planetary gear set and a second planetary gear set, a first clutch configured to selectively transmit mechanical power between a planet carrier and an output shaft, and a second clutch configured to selectively transmit mechanical power between a sun gear and the output shaft.

[0084] It should be noted that the example control and estimation routines included herein can be used with various powertrains, electric drives 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 and 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 the vehicle and / or powertrain control 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 realizing 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.

[0085] 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 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 technology can be applied to a powertrain including different types of propulsion sources, including different types of traction motors, internal combustion engines, and / or transmissions. 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.

[0086] 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. A multi-speed gearbox, characterized in that: include: A planetary assembly, the planetary assembly comprising: a first gear set rotationally coupled to a second gear set; a first clutch configured to selectively couple the first sun gear of the first gear set to an input shaft configured to be rotatably coupled to an electric machine; and A second clutch is configured to selectively couple the second sun gear of the second gear set to the output shaft.

2. The multi-speed gearbox according to claim 1, characterized in that: The second clutch is a one-way clutch.

3. The multi-speed transmission according to claim 1, characterized in that: Also included is a third clutch configured to selectively couple the input shaft to a second sun gear in the second gear set.

4. The multi-speed gearbox according to claim 3, characterized in that: The third clutch is a friction clutch.

5. The multi-speed transmission according to claim 3, characterized in that: Also included is a fourth clutch configured to selectively couple the planet carrier of the second gear set to the output shaft.

6. The multi-speed transmission according to claim 1, characterized in that: The first gear set or the second gear set does not include a ring gear.

7. The multi-speed transmission according to claim 1, characterized in that: The first planet carrier in the first gear set is directly fixedly coupled to the second planet carrier in the second gear set.

8. The multi-speed transmission according to claim 1, characterized in that: The ring gear of the second gear set or the ring gear of the first gear set is grounded.

9. The multi-speed transmission according to claim 1, characterized in that: The planetary assembly includes a first ring gear of the first gear set and a second ring gear of the second gear set, and the multi-speed transmission includes a first brake configured to selectively ground the first ring gear and a second brake designed to ground the second ring gear.

10. The multi-speed transmission according to claim 1, characterized in that: The multi-speed transmission is configured to operate in at least four different gear stages, and the multi-speed transmission further includes a controller comprising: instructions which, when executed during forward drive, cause the controller to: The electric motor is caused to rotate in a common direction in the first gear stage, the second gear stage, the third gear stage, and the fourth gear stage.

11. The multi-speed transmission according to claim 1, characterized in that: A shaft is directly coupled to the second sun gear and the second clutch.

12. The multi-speed transmission according to claim 1, characterized in that: The multi-speed gearbox is configured to shift between only four discrete gear stages.

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