SEPARATE SINGLE-GEAR AND TWO-GEAR AXLE PLANS

Abstract

Rear drive module (100, 100', 100", 100A) having a case (108, 108'), a gear (118, 118') which is mounted in the housing (108, 108') for rotation about a first axis, a ring gear (122, 122') which is in meshing engagement with the gear (118, 118') and can rotate about a second axis, wherein the ring gear (122, 122') is supported for rotation relative to the housing (108, 108') by a pair of tapered roller bearing assemblies (158) which are arranged laterally and on the same side of the ring gear (122, 122') along the second axis, a pair of axle shafts (102L, 102R, 102L', 102R'), and a differential (110, 110', 110", 110A) which is housed in the casing (108, 108') and is arranged driving between the axle shafts (102L, 102R, 102L', 102R') and the ring gear (122, 122'), wherein the differential (110, 110', 110", 110A) has a pair of output elements (128, 182, 182', 188, 188'), wherein each of the output elements (128, 182, 182' 188, 188') is driven by a corresponding one of the axle shafts (102L, 102R, 102L', 102R'), wherein the rear drive module (100, 100', 100", 100A) also has a torque transmission device (112, 112', 112A) which is coupled to the differential (110, 110', 110", 110A) and can be used to disengage the gear (118, 118') from the axle shafts (102L, 102R, 102L', 102R'), wherein the torque transmission device (112, 112', 112A) is arranged between the ring gear (122, 122') and an input element (124, 124', 180, 180') of the differential (110, 110', 110", 110A), and either a) the differential (110', 110A) has a planetary gear set (184, 184') and an output element (168', 168A) of the torque transmission device (112', 112A) is coupled to an outer gear (180, 180') of the planetary gear set (184, 184') for common rotation, or b) the differential (110, 110") has a pair of output side gears (128) which are accommodated in a differential housing (124, 124') and an output element (168, ) of the torque transmission device (112, 112', 112A) is coupled to the differential housing (124, 124') for common rotation.

Description

TECHNICAL AREA

[0001] The present disclosure relates generally to all-wheel drive vehicles and in particular to separable single-speed and multi-speed drive trains for all-wheel drive vehicles. BACKGROUND

[0002] This section provides background information on the present disclosure, which is not necessarily the state of the art.

[0003] Many modern vehicles, such as crossovers, are equipped with an all-wheel drive (AWD) system based on a front-wheel drive (FWD) layout. This optional drivetrain configuration allows the drive torque to be selectively and / or automatically distributed by the drive system to both the primary (i.e., front) and secondary (i.e., rear) drivetrains to provide better traction when the vehicle is driven in adverse weather or off-road conditions. Such AWD vehicles necessarily have a much more complex drivetrain, which, in addition to the primary drivetrain, must include the additional components belonging to the secondary drivetrain, such as the power take-off unit and driveshaft.

[0004] To minimize the drivetrain losses (i.e., viscous friction resistance, friction, inertia, and oil foaming) associated with the secondary drivetrain during reverse drive when no drive torque is transmitted to it, it is known to insert a disconnect system configured to decouple components of the secondary drivetrain from the rest of the secondary drivetrain, for example, the rear wheels or the rear differential. For this purpose, there is a need in this field to develop improved disconnectable drivetrains for use in AWD vehicles.

[0005] From US 7 150 694 B2 and EP 2 116 411 A1, powertrain arrangements for motor vehicles with a primary powertrain and a secondary powertrain are known, which provide a coupling and disconnecting device for coupling and disconnecting the primary and secondary powertrains.

[0006] The object of the invention is to further develop a drive train arrangement of the type mentioned above in such a way that a particularly effective coupling and decoupling of the secondary drive train can be enabled. SUMMARY

[0007] One aspect of the present teaching is to provide a separable secondary drivetrain arrangement for use in all-wheel drive vehicles, comprising a single-speed power take-off unit with a disconnect mechanism, a single-speed rear drive module having a torque transmission device capable of providing a disconnect function, a speed synchronization function and a torque control function, and a control system for controlling the actuation of the disconnect mechanism and the torque transmission device.

[0008] Another aspect of the present teaching is to provide a separable secondary drivetrain arrangement for use in all-wheel drive vehicles, comprising a two-speed power take-off unit with a disconnect mechanism and a gear shifting mechanism, a two-speed rear drive module having a torque transmission device and a gear shifting mechanism, and a control system for controlling the coordinated actuation of the two-speed power take-off unit and the two-speed rear drive module.

[0009] In accordance with these and other aspects of the present teaching, an all-wheel-drive vehicle may comprise a drive system, a primary drivetrain, a power transfer mechanism, a secondary drivetrain, and a control system. The drive system may include a primary drive and a transmission with one output. The primary drivetrain is driven by the transmission output and can be operated to direct rotational power from the primary drive to a pair of first vehicle wheels. The power transfer mechanism may be operated, with the aid of the control system, either in a separate mode or in a linked mode. In its linked mode, the power transfer mechanism may be operated to direct rotational power from the transmission output to the secondary drivetrain.The secondary drivetrain can include a rear drive module and a driveshaft that couples an output of the power-shift mechanism to an input of the rear drive module. The rear drive module can include a secondary differential, which connects a pair of axle shafts and a pair of secondary vehicle wheels, and a torque transfer device, which is operationally located between the input and the secondary differential. The torque transfer device can be operated in either a separate mode or a linked mode by means of the control system. In its linked mode, the torque transfer device can be operated to direct the torque transmitted by the power-shift mechanism to the secondary differential.When the power shift mechanism and torque transfer device are in their separate modes, torque is transmitted only to the front wheels. The torque transfer device can be operated in its separate mode to prevent the rear wheels and the secondary differential from driving the input of the rear drive module, the driveshaft, and the output of the power shift mechanism in reverse. The power shift mechanism can also be operated in its separate mode to prevent the transmission output from driving the output of the power shift mechanism and the driveshaft.

[0010] In addition to the above, an all-wheel-drive vehicle according to the present teaching may also include a two-speed power shift mechanism and a two-speed rear-wheel-drive module. The two-speed power shift mechanism can still be operated in a separate and a connected mode, but it still features a two-speed gear unit operationally arranged between the transmission output and a primary differential that drives the first wheels of the vehicle. The power shift mechanism can establish a two-wheel drive connection with a high gear ratio, a four-wheel drive connection with a high gear ratio, and a four-wheel drive connection with a low gear ratio between the transmission output and the primary differential.The two-speed rear-wheel-drive module remains operational in its separate and linked modes, but it also includes a two-speed gear shift unit operationally located between an output of the torque transfer device and the secondary differential. The rear-wheel-drive module can establish a high-speed drive link and a low-speed drive link between the output of the torque transfer device and an input to the secondary differential. The control system can be operated to coordinate the actuation of the two-speed power shift mechanism and the two-speed rear-wheel-drive module.

[0011] Further areas of applicability will become apparent in the following description and claims. The description and specific examples in this summary are for illustrative purposes only and are not intended to limit the scope of this disclosure.

[0012] The following embodiments can be advantageously combined with one another unless otherwise indicated. 1. A drive system for a motor vehicle with all-wheel drive, wherein the drive system comprises the following: a primary drivetrain comprising a first differential, wherein the primary drivetrain is configured to drive a pair of first vehicle wheels, the differential comprising a first differential housing; a power-shifting mechanism comprising an input shaft configured to receive torque from a drive assembly, a first two-gear gear unit arranged between the input shaft and the first differential, which can be operated to couple the input shaft and the first differential housing for common rotation in a first gear mode, and in a second gear mode to establish a reduced-ratio drive connection between the input shaft and the differential housing, an output gear shaft, and a disengaging mechanism which can be operated in a coupled mode to allow the transmission of torque between the input shaft and the output gear shaft, and in a disengaged mode to prevent the transmission of torque between the input shaft and the output gear shaft; and a second drivetrain comprising a longitudinal shaft and a rear drive module, the rear drive module comprising a second differential, an input gear shaft driving a ring gear, a torque transmission device, and a second two-speed gear unit, the second differential having an input element and a pair of output elements configured to drive a pair of second vehicle wheels, the input gear shaft being coupled through the longitudinal shaft to the output gear shaft of the power shifting mechanism, the second two-speed gear unit comprising a planetary gear assembly and a gear shifting mechanism, the torque transmission device being configured to enclose the planetary gear assembly and comprising a clutch input element driven by the ring gear, a clutch output element driving the planetary gear assembly, and a clutch pack.which is operationally arranged between the input clutch element and the output clutch element, wherein the torque transmission device can be operated in a first mode to permit the transmission of torque from the clutch input element to the clutch output element, and in a second mode to prevent the transmission of torque from the clutch input element to the clutch output element, wherein the gear shifting mechanism can be operated in a first gear shift mode to establish a drive connection with a first gear ratio between the clutch output element and the input element of the second differential, and in a second gear shift mode to establish a drive connection with a second gear ratio between the planetary gear arrangement and the input element of the second differential. 2. Drive assembly according to embodiment 1, wherein the power switching mechanism is a power take-off unit comprising a distribution gear arrangement which drives the output gear shaft, wherein the first two-speed gear unit comprises a planetary gear set and a gear sleeve, wherein the planetary gear set has a non-rotating ring gear, a sun gear, a plurality of planet gears which mesh with the ring gear and the sun gear, and a planet carrier on which the planet gears are rotatably mounted and which is attached to the first differential housing for rotation, wherein the gear sleeve is coupled to the input shaft for common rotation and is axially displaceable between a first gear position in which the gear sleeve connects the input shaft to the planet carrier and a second gear position in which the input shaft is connected to the sun gear. 3. Drive assembly according to embodiment 2, wherein the separation mechanism comprises a mode sleeve which is coupled to the gear stage sleeve for common rotation and sliding movement between a first operating position and a second operating position, wherein the mode sleeve connects the transfer case assembly to the gear stage sleeve when it is positioned in its first operating position, and wherein the mode sleeve is disengaged from the transfer case assembly when the mode sleeve is positioned in its second operating position. 4. Drive assembly according to embodiment 3, wherein the gear stage sleeve encloses a part of the input shaft and is axially displaceable thereon between its first and second gear stage positions, wherein the distribution gear arrangement comprises a distribution shaft that encloses a part of the input shaft and the gear stage sleeve, and wherein the mode sleeve encloses a part of the gear stage sleeve and is axially displaceable thereon between its first operating position and its second operating position. 5. Drive assembly according to embodiment 1, wherein the planetary gear arrangement comprises a sun gear which is attached for rotation with the clutch output element, a ring gear, a planet carrier which is attached for rotation with the input element of the second differential, and planet gears which are rotatably mounted on the planet carrier and which mesh with the sun gear and the ring gear, and wherein the gear shifting mechanism comprises a gear shift sleeve which is axially displaceable between a first and a second gear position in order to establish the first and second gear modes. 6. Drive assembly according to embodiment 5, wherein the gear shifting mechanism further comprises a first clutch ring which is attached to the clutch output element for rotation, a second, non-rotatable clutch ring and a third clutch ring which is coupled to the input element of the second differential for rotation, wherein the gear stage sleeve is attached to the ring gear for rotation and is axially displaceable between its first and second gear stage positions. 7. Drive assembly according to embodiment 6, wherein the gear stage sleeve can be operated in its first gear stage position to engage releasably in the first clutch ring and the third clutch ring to establish a direct connection between the clutch output element and the input element of the second differential, and wherein the gear stage sleeve can be operated in its second gear stage position to engage releasably in the second clutch ring, so that the ring gear is held against rotation and causes the planet carrier to be driven at a reduced speed relative to the sun gear. 8. Drive assembly according to embodiment 7, wherein the second differential is a bevel differential assembly, with a second differential housing as its input element and a pair of output side gears as its output elements, wherein the third clutch ring is attached to rotate with the second differential housing, and wherein the second differential housing is attached to rotate with the planet carrier of the planetary gear assembly. 9. Drive assembly according to embodiment 7, wherein the second differential is a planetary differential arrangement having an outer gear as its input element, a sun gear as one of its output elements, a carrier as its other output element, and first and second planet gears rotatably mounted on the carrier, wherein the first planet gear is in engagement with the outer gear and the second planet gear is in engagement with the sun gear, and wherein the first planet gear is in engagement with the second planet gear. 10. Drive assembly according to embodiment 5, wherein the coupling input element is a coupling bell driven by the ring gear, and the coupling output element is a coupling hub attached to the sun gear for rotation, and wherein the coupling hub encloses the ring gear and the coupling bell encloses the coupling hub. 11. Drive assembly according to embodiment 5, wherein the power switching mechanism is a power take-off unit comprising a distribution gear arrangement that drives the output gear shaft, wherein the first two-speed gear unit comprises a planetary gear set and a gear sleeve, wherein the planetary gear set has a non-rotating ring gear, a sun gear, a plurality of planet gears meshing with the ring gear and the sun gear, and a planet carrier on which the planet gears are rotatably mounted and which is attached to the first differential housing for rotation, wherein the gear sleeve is coupled to the input shaft for common rotation and is axially displaceable between a first gear position in which the gear sleeve connects the input shaft to the planet carrier and a second gear position in which the gear sleeve connects the input shaft to the sun gear. 12. Drive assembly according to embodiment 11, wherein the separation mechanism comprises a mode sleeve which is coupled to the gear stage sleeve for common rotation and sliding movement between a first operating position and a second operating position, wherein the mode sleeve connects the transfer case assembly to the gear stage sleeve when it is positioned in its first operating position, and wherein the mode sleeve is disengaged from the transfer case assembly when the mode sleeve is positioned in its second operating position. 13. Drive system according to embodiment 12, wherein a two-wheel drive mode with a high gear ratio is produced for the motor vehicle when the mode sleeve is in its second operating position, the gear ratio sleeve is in its first gear ratio position, and the torque transmission device is in its second mode, whereby substantially all of the rotational force is transmitted through the primary drive train to the first vehicle wheels, and the input gear shaft of the rear drive module and the longitudinal shaft are not reverse driven by the second differential. 14. Drive system according to embodiment 12, wherein an all-wheel drive mode with a high gear ratio is produced for the motor vehicle when the mode sleeve is in its first operating position, the gear ratio sleeve is in its first gear ratio position, the torque transmission device is operated in its first mode, and the gear ratio sleeve is in its first gear ratio position. 15. Drive system according to embodiment 12, wherein an all-wheel drive mode with a low gear ratio is produced for the motor vehicle when the mode sleeve is in its first operating position, the gear ratio sleeve is in its second gear ratio position, the torque transmission device is operated in its first mode, and the gear ratio sleeve is in its second gear ratio position. 16. Drive system according to embodiment 1, wherein a two-wheel drive mode with a high gear ratio is produced for the motor vehicle when the separating mechanism can be operated in its separated mode, the first two-speed gear unit can be operated in its first gear mode and the torque transmission device can be operated in its second mode, whereby the second differential does not drive the input gear shaft and the longitudinal shaft in reverse. 17. Drive system according to embodiment 1, wherein a high-gear all-wheel drive mode is produced for the motor vehicle when the disconnecting mechanism can be operated in its connected mode, the first two-speed gear unit can be operated in its first gear mode, the torque transmission device can be operated in its first mode, and the second two-speed gear unit can be operated in its first gear mode. 18. Drive system according to embodiment 1, wherein a low-gear all-wheel drive mode is produced for the motor vehicle when the disconnecting mechanism can be operated in its connected mode, the first two-speed gear unit can be operated in its second gear mode, the torque transmission device can be operated in its first mode, and the second two-speed gear unit can be operated in its second gear mode. 19. Drive system for a motor vehicle with all-wheel drive, wherein the drive system comprises the following: a primary drivetrain comprising a first differential, wherein the primary drivetrain is configured to drive a pair of first vehicle wheels, the first differential having a first differential housing; a power switching mechanism comprising an input shaft configured to receive torque from a drive system, a first two-speed gear unit arranged between the input shaft and the first differential, which can be operated to couple the input shaft and the differential housing for common rotation in a first gear mode, and in a second gear mode to establish a drive connection with a reduced gear ratio between the input shaft and the first differential housing, an output gear shaft, and a disengaging mechanism which can be operated in a coupled mode to allow the transmission of torque between the input shaft and the output gear shaft, and in a disengaged mode to prevent the transmission of torque between the input shaft and the output gear shaft; and a second drivetrain comprising a longitudinal shaft and a rear drive module, the rear drive module comprising a second differential, an input gear shaft driving a ring gear, a torque transmission device, and a second two-speed gear unit, the input gear shaft being coupled to the output gear shaft of the power shifting mechanism via the longitudinal shaft, the second differential being configured to drive a second pair of vehicle wheels and having a second differential housing, the second two-speed gear unit comprising a planetary gear assembly and a gear shifting mechanism, the torque transmission device being configured to enclose the planetary gear assembly, and comprising a clutch input element driven by the ring gear, a clutch output element driving the planetary gear assembly, and a clutch pack.which is operationally arranged between the input clutch element and the output clutch element, wherein the torque transmission device can be operated in a first mode to allow the transmission of torque from the clutch input element to the clutch output element, and in a second mode to prevent the transmission of torque from the clutch input element to the clutch output element, wherein the gear shifting mechanism can be operated in a first gear shift mode to establish a drive connection with a first gear ratio between the clutch output element and the second differential housing, and in a second gear shift mode to establish a drive connection with a second gear ratio between the planetary gear arrangement and the second differential housing. 20. Drive assembly according to embodiment 19, wherein the planetary gear arrangement comprises a sun gear mounted for rotation with the clutch output element, a ring gear, a planet carrier mounted for rotation with the second differential housing, and planet gears rotatably mounted on the planet carrier and meshing with the sun gear and the ring gear, wherein the gear shifting mechanism comprises a first clutch ring mounted for rotation with the clutch output element, a second non-rotatable clutch ring, a third clutch ring mounted for rotation with the second differential housing, and a gear shift sleeve coupled for rotation with the ring gear and axially displaceable between the first and second gear positions, wherein the gear shift sleeve can be operated in its first gear position to establish the first gear mode.by detachably coupling the first clutch ring with the third clutch ring, and wherein the gear stage sleeve can be operated in its second gear stage position to produce the second gear stage mode by detachably coupling the ring gear with the second clutch ring. DRAWINGS

[0013] The drawings described herein are intended only to illustrate the selected embodiments and are not intended to limit the scope of this disclosure in any way. Similar or identical elements are assigned consistent reference numerals in the various figures.

[0014] The present revelation will be better understood with the help of the detailed description and the accompanying drawings: Fig. 1 is a scheme of a motor vehicle equipped with a separable all-wheel drive system constructed in accordance with the present teaching; Fig. Figure 2 is a schematic representation of a single-speed power take-off unit, which is connected to the separable all-wheel drive system of Fig. 1 is assigned; Fig. 3 to Fig. Figure 5 shows perspective views of a single-speed power take-off unit based on the design in Fig. 2 shown schemes with the housing structure removed for better overview, and which is constructed in accordance with the present teaching; Fig. Figure 6 is a sectional view of a single-speed power take-off unit, generally located along line 6-6 of Fig. 5 is recorded; Fig. Figure 7 is a schematic representation of a single-speed rear-wheel drive module that is part of the separable all-wheel drive system of Fig. 1 is assigned; Fig. Figure 8 is a sectional view of a single-speed rear-wheel drive module based on the one described in Fig. 7 schemes shown, and which is structured in accordance with the present teaching; Fig. Figure 9 is a sectional view of another single-speed rear-wheel drive module constructed in accordance with the present teaching and which also serves the separable all-wheel drive system of Fig. 1 can be assigned; Fig. 10 is a scheme of a motor vehicle equipped with a different configuration of a separable all-wheel drive system constructed in accordance with the present teaching; Fig. Figure 11 is a schematic representation of a two-speed power take-off unit that feeds into the separable all-wheel drive system of Fig. 10 is assigned; Fig. Figure 12 is a perspective exploded view of a two-speed power take-off unit based on the one described in Fig. 11 schemes shown, and which is constructed in accordance with the present teaching; Fig. Figure 13 is a sectional view of a two-speed power take-off unit, which is located in Fig. 11 is shown; Fig. Figures 14A to 14D are partial sectional views of a two-speed power take-off unit, which is located in Fig. 13 is shown with its mode and gear shift components, which are positioned to define a two-wheel high-gear mode (2-Hi), a four-wheel high-gear mode (4-Hi), a neutral idle mode and a four-wheel low-gear mode (4-Low); Fig. Figure 15 is a schematic representation of a two-speed rear-wheel drive module that is part of the separable all-wheel drive system of Fig. 10 is assigned; Fig. Figures 16A to 16C are sectional views of a two-speed rear-wheel drive module based on the one described in Fig. 15 schemes shown, whose gear-shifting components are positioned to define a high gear mode (H), a neutral mode (N) and a low gear mode (L); and Fig. Figure 17 is a diagram of another two-speed rear-wheel drive module, which is part of the separable all-wheel drive system of Fig. 10 is assigned. DETAILED DESCRIPTION

[0015] The following exemplary embodiments are provided to complete the present disclosure and fully communicate its scope to those skilled in the art. Numerous specific details are included, such as examples of specific components, devices, and schematic configurations, to provide a complete understanding of exemplary embodiments of the present disclosure. However, it is evident to those skilled in the art that these specific details need not be applied, that these exemplary embodiments can be implemented in many different forms, and that none of them is intended to limit the scope of the present disclosure.

[0016] With reference to Fig. Figure 1 of the drawings schematically depicts a motor vehicle constructed in accordance with the teaching of the present disclosure and is generally designated by reference numeral 10. The vehicle 10 may have a drive system 12 and a drive assembly 14, which may comprise a primary drive train 16, a power switching mechanism 18, a secondary drive train 20, and a control system 22. In the various aspects of the present teaching, the primary drive train 16 may be a front-wheel drive, while the secondary drive train 20 may be a rear-wheel drive.

[0017] The drive system 12 can comprise a primary drive 24, such as an internal combustion engine or an electric motor, and a transmission 26, which can be any type of gear-change mechanism, such as a manual, automatic, or continuously variable transmission. The primary drive 24 can be operated to provide torque for the primary drive train 16 and the power transmission mechanism 18.

[0018] With additional reference to Fig. 2. The primary drivetrain 16 can comprise a primary or first differential 30 with an input element 32 driven by an output element (not shown) of the transmission 26. In the particular design shown, the first differential 30 is configured as part of the transmission 26, a type conventionally referred to as a transaxle and typically used in front-wheel-drive vehicles. The primary drivetrain 16 can further comprise a pair of first axle shafts 34L, 34R, which can couple output elements of the first differential 30 to a set of first vehicle wheels 36L, 36R.The first differential 30 can comprise a first differential housing 38 rotatably driven by the input element 32, at least one pair of first gears 40 rotatably driven by the first differential housing 38, and a pair of first output side gears 42 meshing with the first gears 40 and connected to drive the first axle shafts 34L, 34R.

[0019] With continued reference to Fig. 2 The power take-off unit (PTU) 18, hereinafter referred to herein as the power take-off unit, can generally comprise a housing 46, an input 48 coupled for common rotation with the first differential housing 38 of the first differential 30, an output 50, a distribution gear assembly 52, a disengagement mechanism 54, and a disengagement actuator 56. The input 48 can comprise a tubular input shaft 58 rotatably mounted in the housing 46 and concentrically enclosing a portion of the first axle shaft 34R. A first end of the input shaft 58 can be coupled for rotation with the first differential housing 38. The output 50 can comprise an output gear shaft 60 rotatably mounted in the housing 46 and having a gear 62. The distribution gear arrangement 52 can comprise a hollow distribution shaft 64, a helical gear set 66 and a ring gear 68 which meshes with the gear 62.The distributor shaft 64 concentrically surrounds part of the first axle shaft 34R and is rotatably mounted in the housing 46. The helical gear set 66 can comprise a first helical gear 70, which is fixed to rotate with the distributor shaft 64, and a second helical gear 72, which meshes with the first helical gear 70. The second helical gear 72 and the ring gear 68 are integrally formed on a stub shaft 74, which is rotatably mounted in the housing 46, or are fixed to it for common rotation.

[0020] The disconnecting mechanism 54 can comprise any type of clutch, disconnecting, or coupling device that can be used to selectively transmit torque from the drive system 14 to the secondary drive train 20. In the particular example provided, the disconnecting mechanism 54 is designed as a jaw clutch. The jaw clutch can comprise a set of external splined teeth 76 formed on a second end of the input shaft 58, a set of external clutch teeth 78 formed on the distributor shaft 64, a mode sleeve 80 with internal splined teeth 82 that are constantly engaged with the external splined teeth 76 on the input shaft 58, and a shift fork 84 that can be operated to axially displace the shift sleeve 80 between a first operating position and a second operating position.Although schematically represented as a non-synchronized jaw coupling, it is understood that the separation mechanism 54 may include a synchronized jaw coupling if such a configuration is desired.

[0021] The mode sleeve 80 is shown in its first operating position, designated by connecting line “2WD”, in which the internal splines 82 on the mode sleeve 80 are disengaged from the external clutch teeth 78 on the distributor shaft 64. Thus, the input shaft 58 is disconnected from the driven engagement with the distributor shaft 64. Consequently, no torque is transmitted from the drive system 12 to the distributor assembly 52 and the output gear shaft 60 of the power take-off unit 18. When the mode sleeve 80 is in its second operating position, designated by connecting line “AWD”, the internal splines 82 are engaged with both the external splines 76 on the input shaft 58 and the external clutch teeth 78 on the distributor shaft 64.Accordingly, the mode sleeve 80 establishes a drive connection between the input shaft 58 and the distributor shaft 64, so that torque is transmitted from the drive system 12 via the auxiliary output unit 18 to the output gear shaft 60. As will be described in detail later, the output gear shaft 60 is coupled to the secondary drive train 20 via a longitudinal shaft 86.

[0022] The separating actuator 56 can be any type of actuator mechanism that can be operated to move the switching fork 84 axially, which in turn causes a synchronous axial displacement of the mode sleeve 80 between its two different operating positions. The separating actuator 56 is shown mounted on the housing 46 of the power take-off unit 18. The separating actuator 56 can be a power-driven mechanism that can receive control signals from the control system 22 and can include, for example, hydraulically actuated, pneumatically actuated, or electromechanically actuated arrangements.

[0023] As noted, Fig. 2 schematically represents the components that may belong to the auxiliary drive unit 18. With reference now to Fig. Figures 3 to 6 provide a more significant structural configuration of such components, which are associated with an exemplary embodiment of the power take-off unit 18. In particular, these drawings show the components in an assembled state, with the housing 46 removed for clarity. All components—the input shaft 58, the distributor shaft 64, the stub shaft 74, and the output gear shaft 60—are shown with suitable bearings mounted on them to rotatably support each one in or on the housing 46. The disconnect actuator 56 is shown as a separate, power-driven unit 88, from which the shift fork 84 projects. The power-driven unit 88 may include an electric motor and a gear drive unit configured to convert the rotation of the motor output into a sliding motion of the shift fork 84.External splines 90 are arranged on one end of the first axle shaft 34R to enable a splined connection between the corresponding first side gear 42 in the first differential 30. External splines 92 are also provided on the first end of the input shaft 58 to enable a splined connection with a matching area of ​​the first differential housing 38.

[0024] With particular reference to Fig. 1 and Fig. 7 The second drive train 20 can comprise the longitudinal shaft 86, a rear drive module (RDM) 100, a pair of second axle shafts 102L, 102R and a pair of second vehicle wheels 104L, 104R. A first end of the longitudinal shaft 86 can be coupled for rotation to the output gear shaft 60, which protrudes from the auxiliary power unit 18, while a second end of the longitudinal shaft 86 can be coupled for rotation to an input assembly 106 of the rear drive module 100. The rear drive module 100 may include a housing 108, a secondary or second differential 110, a torque transfer device (TTD) 112, which is generally configured and arranged to selectively couple and transfer torque from the input arrangement 106 to the second differential 110, and a TTD actuator 114.The input assembly 106 can comprise an input gear shaft 116 with a gear 118, a hollow bearing housing 120, and a ring gear 122, which is mounted to rotate with the bearing housing 120 and meshes with the gear 118. The second differential 110 can comprise an input element, for example, a second differential housing 124, at least one pair of second gears 126 rotatably driven by the first differential housing 124, and a pair of output elements, such as second output lateral gears 128, which mesh with the second gears 126. The second output lateral gears 128 are mounted to rotate with the inner ends of the second axle shafts 102L, 102R. The second differential 110 and the torque transmission device 112 are shown arranged on one side of the input gear shaft 116 to provide a compact arrangement.

[0025] The torque transmission device 112 can include any type of clutch or coupling device that can be used to selectively transmit rotational force from the input assembly 106 to the second differential 110. In the example shown, the torque transmission device 112 is a multi-plate friction clutch that can include an input clutch element 130 driven by the ring gear 122, an output clutch element 132 coupled to the second differential housing 124 for rotation, a multi-plate clutch pack 134 comprising a plurality of overlapping clutch discs arranged between the input and output clutch elements, and an engagement element 136 movable to selectively exert a clutch engagement force on the clutch pack 134. The torque transmission device 112 is shown to generally enclose a portion of the second differential 110.The TTD actuator 114 is provided to generate a displacement movement of the engagement element 136 relative to the coupling package 134 and can be controlled by control signals from the control system 22.

[0026] A first or “separate” mode can be established for the torque transmission device 112 when the engagement element 136 is positioned such that rotational force is not transmitted from the input clutch element 130 to the output clutch element 132. In this “separate” mode, the second vehicle wheels 104L, 104R, the second axle shafts 102L, 102R, the second differential 110, and the output clutch element 132 are disconnected from the input 106 of the rear drive module 100. Thus, the rotation of these components resulting from the rolling motion of the second vehicle wheels 104L, 104R does not result in a “reverse drive” of the input gear shaft 116, the drive shaft 86, and the components of the power take-off unit 18.

[0027] A second, or "connected," mode can be provided for the torque transmission device 112 when the clutch engagement force exerted by the engagement element 136 on the clutch pack 134 causes the transmission of torque from the input 106 to the second differential housing 124, which is then delivered via the second differential 110 to the second vehicle wheels 104L, 104R. Additionally, a "torque control function" can also be provided in connected mode, since variable control of the magnitude of the clutch engagement force exerted on the clutch pack 134 can vary the distribution ratio of the torque transmitted from the drive system 12 to the primary drive train 16 and the secondary drive train 20.Consequently, the torque transmission device 112 can be configured or controlled to slip or to engage and disengage cyclically as is suitable for influencing the available drive torque while the drive connection between the input 106 and the second differential 110 is established.

[0028] The TTD actuator 114 can be any power-driven device that can switch the torque transmission device 112 between its first and second modes and adaptively control the magnitude of the clutch engagement force exerted by the engagement element 136 on the clutch assembly 134. Thus, the TTD actuator 114 can, for example, comprise an electromagnetically or motor-driven ball screw or ball ramp, or another cam actuation system, which has a mechanical connection, shown by connecting line 140, with the engagement element 136. Alternatively, the TTD actuator 114 can comprise a hydraulic actuation system that can control the position of the engagement element 136 relative to the clutch assembly 134 by regulating the fluid pressure, also shown by connecting line 140, supplied to a pressure chamber.

[0029] Tax system 22 will be used in Fig. Figure 1 shows a schematic representation of the system, comprising a control unit 150, a group of first sensors 152, and a group of second sensors 154. The group of first sensors 152 can be located within the motor vehicle 10 to detect a vehicle parameter and, in response, generate a first sensor signal. The vehicle parameter can be any combination of the following: vehicle speed, yaw rate, steering angle, engine torque, wheel speeds, shaft speeds, lateral acceleration, longitudinal acceleration, throttle position, and transmission position, without restriction. The group of second sensors 154 can be configured to detect driver-initiated input to one or more onboard devices and / or systems in the vehicle 10 and, in response, generate a second sensor signal.The vehicle 10 can, for example, be equipped with a sensor associated with a mode selection device, such as a switch, push button, or lever, which detects when the vehicle operator has selected a vehicle operating mode between two-wheel drive (FWD) and all-wheel drive (AWD). The controlled operation of vehicle systems, such as the windshield wipers, defroster, and / or heating system, can also be used by the control unit 150, for example, to assess whether the vehicle 10 should automatically switch between FWD and AWD modes.

[0030] As noted, Fig. Figure 7 schematically depicts the components that may belong to the rear drive module 100. Referring to Fig. A more significant structural configuration of such components, associated with an exemplary embodiment of the rear drive module 100, is now shown in Figure 8. Specifically, the ring gear 122 can be attached to a radial flange portion 156 of the bell-shaped bearing housing 120, which in turn is rotatably mounted on the housing 108 by a pair of laterally spaced bearing assemblies 158. A threaded nut 160 is installed on a threaded section of the bearing housing 120 and can be axially adjusted to vary the preload applied to the bearing assemblies 158. The second differential housing 124 has a hub extension 162, which can be rotatably mounted within an enlarged bell-shaped area 164 of the bearing housing 120. The input clutch element 130 can be operationally associated with the ring gear 122 and can include a cylindrical clutch bell 166, which is attached to the ring gear 122 or integrally formed with it.The output clutch element 132 can be associated with the second differential housing 124 and can include a clutch hub 168 that is attached to or integrally formed with the outer surface of the second differential housing 124. A set of inner clutch discs of the clutch pack 134 can mesh with the clutch hub 168, while a set of outer clutch discs meshes with the clutch bell 166. As noted, the torque transmission device 112 is configured to enclose a portion of the second differential 110 to provide a compact arrangement. The engagement element 136 can include a pressure piston assembly 170, which is operatively arranged for sliding movement within a pressure chamber 172 and to which pressurized fluid can be supplied by a hydraulically actuated unit associated with the TTD actuator 114.

[0031] Referring to Fig. Figure 9 shows an alternative exemplary embodiment of the rear drive module 100, designated by reference numeral 100A. The rear drive module 100A is generally similar to the rear drive module 100, but is equipped with a second planetary differential 110A instead of the second bevel gear differential 110, which is located in Fig. 7 and Fig. Figure 8 shows that the second planetary differential 110A can comprise an outer gear 180, a sun gear 182, a set of first planet gears 184, a set of second planet gears 186, and a carrier unit 188, by which the first planet gears 184 and the second planet gears 186 are rotatably mounted. The first planet gears 184 can mesh with the outer gear 180, while the second planet gears 186 can mesh with the sun gear 182. The first and second planet gears are arranged circumferentially such that each of the first planet gears 184 is also meshed with at least one of the second planet gears 186. The outer gear 180 acts as the input element for the second differential 110A, while the carrier unit 188 and the sun gear 182 function as a pair of output elements.The carrier unit 188 can include a tubular bead 190 rotatably mounted within the bell-shaped part 164 of the bearing housing 120, and which has a set of internal keyways 192 configured to mesh with a set of external keyways (not shown) formed on an inner end of the second axle shaft 102R. Likewise, the sun gear 182 can have a set of internal keyways 194 configured to mesh with a set of external keyways (not shown) formed on an inner end of the second axle shaft 102L.

[0032] The torque transmission device 112A, which is associated with the second differential 110A, can comprise a clutch bell 166A, which is attached to the ring gear 122 for rotation, a clutch hub 168A, which is attached to the outer gear 180 for rotation, a clutch pack 134A, which is operationally arranged between them, and a clutch engagement element 136A, which can be operated to exert a clutch engagement force on the clutch pack 134A in response to control signals sent from the control system 22 to the TTD actuator 114. Thus, every rotational force transmitted from the input 106 via the clutch pack 134A drives the outer gear 180 and is transmitted via the sun gear 182 or the carrier unit 186 to the second axle shafts 102L, 102R, while the meshing pairs of the first planet gears 184 and the second planet gears 186 facilitate the speed differentiation between the second vehicle wheels 104L, 104R.

[0033] With reference to the Fig. 1, Fig. 2 and Fig. 7 The vehicle 10 can normally be operated in two-wheel drive (FWD) mode, in which the power take-off unit 18 and the rear drive module 100 are both disengaged. In particular, the mode sleeve 80 of the disconnect mechanism 54 is positioned in its first operating position by the disconnect actuator 56 such that the input shaft 58 is decoupled from the distribution shaft 64. Thus, essentially all the power provided by the drive system 12 is transferred to the primary drive train 16. Likewise, the torque transmission device 112 can be switched to its first mode and held there such that the input 106, the drive shaft 86, the output gear shaft 60, and the distribution gear assembly 52 within the power take-off unit 18 are not reverse-driven due to the rolling motion of the second vehicle wheels 104.

[0034] When operation of the motor vehicle 10 in all-wheel drive (AWD) mode is desired or necessary, the control system 22 can be activated via a suitable input, which, as noted, may include an input requested by the driver (via the mode selection device) and / or an input generated by the control unit 150 in response to signals from the first sensors 152 and / or the second sensors 154. The control unit 150 first signals the TTD actuator 114 to switch the torque transmission device 112 into its second mode. Specifically, the control unit 150 controls the operation of the TTD actuator 114 such that the actuating element 136 is moved and a clutch engagement force is exerted on the clutch pack 134 sufficient to synchronize the rotational speed of the secondary drive train 20 with the rotational speed of the primary drive train 16.During speed synchronization, the control unit 150 signals the disconnect actuator 56 to cause the mode sleeve 80 in the power take-off unit 18 to move from its first operating position to its second operating position. When the mode sleeve 80 is in its second operating position, torque is transmitted from the drive system 12 to the primary drive train 16 and the secondary drive train 20. It is clear that the subsequent control of the magnitude of the clutch engagement force generated by the torque transmission device 112 enables torque control via the clutch pack 134 to manage the torque distribution ratio transmitted from the drive system 12 to the primary drive train 16 and the secondary drive train 20.

[0035] With reference to Fig. Figure 10 shows another motor vehicle constructed in accordance with the present teaching and generally designated by reference numeral 10'. Vehicle 10' is generally the same as vehicle 10 of Fig. 1 similar, except that the primary drivetrain 16' and the secondary drivetrain 20', which are associated with the drive system 14', have been modified to include a two-speed gearbox in both the power take-off unit 18' and the rear drive module 100'. As will be explained in detail below, this alternative drive system arrangement for the vehicle 10' allows, in addition to the two-wheel drive high-gear mode and the all-wheel drive high-gear mode associated with the vehicle 10, the production of at least one all-wheel drive low-gear mode. For the sake of clarity, reference symbols with a dash index are used to designate components which are generally similar in structure and / or function to the preceding ones with respect to the Fig. components described in sections 1 to 9, which are not marked with a bar index, are similar.

[0036] Now, with additional reference to Fig. 11 The auxiliary power unit 18' is generally shown to comprise a housing 46', an input 48' configured for connection with an output element of the transmission 26', an output 50', a transfer gear assembly 52', a first differential 30', a disengaging mechanism 54', a two-speed gear unit 198, and a disengaging actuator 56'. The input 48' may comprise a hollow input shaft 204 rotatably mounted on the housing 46' and enclosing the first axle shaft 34L'. The output 50' may comprise an output gear shaft 60' having a gear 62'. The transfer gear assembly 52' may comprise a hollow distribution shaft 64', a helical gear set 66', and a ring gear 68' meshing with the gear 62'.The helical gear set 66' can comprise a first helical gear 70', which is attached to the distributor shaft 64' for rotation, and a second helical gear 72', which meshes with the first helical gear 70'. The second helical gear 72' and the ring gear 68' are integrally formed on or attached to a stub shaft 74', which is rotatably mounted in the housing 46'.

[0037] The two-speed gear unit 198 can comprise a planetary gear set 200 and a gear shift device 202. The planetary gear set 200 can comprise a ring gear 206, which is non-rotatably attached to the housing 46', a sun gear 208, a plurality of planet gears 210 which mesh with both the ring gear 206 and the sun gear 208, and a planet carrier 212 on which the planet gears 210 are rotatably mounted. The planet carrier 212 is attached to, or integrally formed with, the first differential housing 38' of the first differential 30' for common rotation.

[0038] The gear shift device 202 can comprise a sun gear shaft 220, which surrounds part of the first axle shaft 34L' and is fixed for rotation with the sun gear 208, a carrier shaft 222, which surrounds part of the sun gear shaft 220 and is fixed for rotation with the planet carrier 212, and a tubular gear shift sleeve 224, which encloses parts of the carrier shaft 222, the sun gear shaft 220, and the input shaft 204. The input shaft 204 can have a first end 226, which is connected via a coupling splined shaft 227 ( Fig. 12) is arranged at the output of the transmission 26', and has a second end with a set of extended external splined teeth 228 formed thereon. The gear shift sleeve 224 can include a set of internal splined teeth 230 that continuously engage with the external splined teeth 228 on the input shaft 204. Thus, the gear shift sleeve 224 is coupled to rotate with the input shaft 204 while performing a bidirectional axial sliding motion between a plurality of predefined gear shift positions, which are discussed in more detail below. The gear stage sleeve 224 further defines a set of internal clutch teeth 232 which can be engaged and disengaged with a set of external clutch teeth 234 formed on the carrier shaft 222 or with a set of external clutch teeth 236 formed on the sun gear shaft 220.

[0039] The disconnecting mechanism 54' is generally similar in function to the disconnecting mechanism 54 in that it is configured to selectively connect the input shaft 204 to the transfer case assembly 52' for transmitting torque from the input shaft 204 to the output gear shaft 60' when the four-wheel drive mode is desired. However, the disconnecting mechanism 54' differs in that the drive connection between the input shaft 204 and the transfer case shaft 64' is made indirectly via the gear shift sleeve 224. Specifically, the gear shift sleeve 224 may include a first and second set of external splines 240 and 242, respectively, which can be selectively engaged with the internal splines 244 formed on the mode sleeve 246.Thus, the mode sleeve 246 is coupled to the gear stage sleeve 224 for rotation and can perform a bi-directional axial displacement relative to the gear stage sleeve 224 between a first operating position (2WD) and a second operating position (AWD).

[0040] When the mode sleeve 246 is in its first operating position, a set of internal clutch teeth 248 formed on the mode sleeve 246 is disengaged by the external clutch teeth 78' on the distributor shaft 64', with no torque being transmitted from the input shaft 204 via the distributor assembly 52' to the output gear shaft 60'. In contrast, when the mode sleeve 246 is in its second operating position, the internal splines 244 engage with either a first or a second set of external splines 240 and 242 (depending on the axial position of the gear stage sleeve 224), and their internal clutch teeth 248 engage with the clutch teeth 78' on the distributor shaft 64', thus establishing a drive connection between the input shaft 204 and the output gear shaft 60'.

[0041] The two-speed gear unit 198 can be operated to establish at least two drive connections with different gear ratios between the input shaft 204 and the first differential 30'. In particular, the gear sleeve 224 can be axially displaced between a plurality of predefined gear positions. In a first or "high" (Hi) gear position, the gear sleeve 224 is positioned such that its internal clutch teeth 232 engage with the external clutch teeth 234 on the carrier shaft 222.Since the internal splines 230 on the gear shift sleeve 224 remain in constant meshing engagement with the external splines 228 on the input shaft 204, positioning the gear shift sleeve 224 in its high gear position establishes a first-to-one or direct-drive connection between the input shaft 204 and the carrier shaft 222, which in turn is connected to the first differential housing 38' via the carrier 212. Thus, a 1-to-1 or direct-drive connection is established between the input shaft 204 and the first differential 30'.

[0042] In a second or “neutral” gear position, the gear sleeve 224 is separated from the drive connection with both the carrier shaft 222 and the sun gear shaft 220 in such a way that the input shaft 204 is separated from the first differential 30'.

[0043] In a third or “low” gear position, the gear sleeve 224 is positioned such that its internal clutch teeth 232 engage with the external clutch teeth 236 formed on the sun gear shaft 220. When the gear sleeve 224 is in its low gear position, a second or reduced drive connection is established between the input shaft 204 and the first differential 30'. Specifically, the driven rotation of the sun gear shaft 220 causes the planetary gear set 200 to drive the carrier 212 at a reduced speed relative to the input shaft 204, such that the primary drive train 16' is likewise driven via the first differential 30' at the reduced speed ratio.

[0044] With continued reference to Fig. Figure 11 shows the disconnect actuator 56' positioned next to the housing 46' and can comprise a first shift fork 84' engaging the mode sleeve 246, a second shift fork 250 engaging the gear sleeve 224, and a power-operated unit 252 configured to receive control signals from the control unit 150 and capable of coordinating the movement of the shift forks 84' and 250. The power-operated unit 252 can be any type of unit capable of selectively moving the first shift fork 84' to effect movement of the mode sleeve 246 between its two operating positions, while also selectively moving the second shift fork 250 to effect movement of the gear sleeve 224 between its three gear positions.

[0045] Now, with reference to Fig. 12 and Fig. Figure 13 shows a more significant structural configuration of the components associated with the two-speed power take-off unit 18'. In particular, it represents Fig. Figure 12 shows a perspective exploded view of an exemplary embodiment of the two-speed power take-off unit 18'. The housing 46' is shown to comprise a multi-part assembly having a main housing 258 to which a differential housing 260 and a PTU housing 262 are attached. Fig. Figure 13 is a sectional view showing the compact arrangement of the planetary gear set 200, the gear shift device 202, the transfer case arrangement 52' and the movable mode sleeve 246 and the gear shift sleeve 224.

[0046] It is understood that the bi-directional sliding movement of the gear step sleeve 224 and the mode sleeve 246 can be coordinated to produce a variety of gear step and mode combinations for the two-speed auxiliary drive unit 18' based on control signals from the control unit 150. Referring to Fig. 14A to 14D, these different gear and mode combinations can be presented more clearly.

[0047] Fig. Figure 14A shows the positions of the gear shift sleeve 224 and the mode sleeve 246 for producing a two-wheel mode (2-Hi) with a high gear ratio for the power take-off unit 18'. Specifically, the mode sleeve 246 is shown in its first operating position, while the gear shift sleeve 224 is shown in its first gear position. Thus, the input shaft 204 is coupled to the carrier shaft 222 via the gear shift sleeve 224 to establish the direct drive connection between the drive system 12 and the primary drive train 16'. Simultaneously, the distributor shaft 64' is disconnected from the drive connection with the input shaft 204, thereby disconnecting the secondary drive train 20' from the drive system 12. Thus, torque is transmitted to the primary drive train 16' only from the drive system 12 without reduction.

[0048] Fig. Figure 14B shows the positions of the gear shift sleeve 224 and the mode sleeve 246 for creating a four-wheel mode (4-Hi) with a high gear ratio for the power take-off unit 18'. Specifically, the high gear ratio connection is maintained by the gear shift sleeve 224 remaining in its first gear position, while the mode sleeve 246 is shown shifted into its second operating position. Thus, the mode sleeve 246 establishes a drive connection from the input shaft 204 (via the gear shift sleeve 224) to the distributor shaft 64', in order to also transmit torque from the drive system 12 to the secondary drive train 20'.

[0049] Fig. Figure 14C shows the positions of the gear shift sleeve 224 and the mode sleeve 246 for producing a neutral, undriven mode for the auxiliary power unit 18'. As can be seen, the mode sleeve 246 is held in its second operating position, while the gear shift sleeve 224 has been moved axially into its second gear position such that its internal clutch teeth 232 are disengaged from the external clutch teeth 234 on the carrier shaft 222 and the external clutch teeth 236 on the sun gear shaft 220. Thus, the input shaft 204 is disconnected from both inputs to the primary drive train 16' such that no torque is transmitted from the drive system 12 to the primary drive train 16'.It is also noted that such a movement of the gear stage sleeve 224 to its second gear stage position causes the internal wedge teeth 244 on the mode sleeve 246 to disengage from the first set of external wedge teeth 240 on the gear stage sleeve 224, while the mode sleeve 246 retains its connection with the distributor shaft 64'.

[0050] Fig. Figure 14D shows the positions of the gear shift sleeve 246 and the mode sleeve 224 for producing a four-wheel low-gear mode (4-Low) for the power take-off unit 18'. Specifically, the mode sleeve 246 is held in its second operating position while the gear shift sleeve 224 is moved axially to its third gear position. Consequently, the low-gear drive connection is established by the gear shift sleeve 224 between the input shaft 204 and the sun gear shaft 220, while the AWD connection is established by the mode sleeve 246. It is noted that when the gear shift sleeve 224 moves from its neutral gear position to its low-gear position, the internal splines 244 of the mode sleeve 246 engage with the second set of external splines 242.While it is possible to provide the external wedge teeth 240 and 242 on the step sleeve 224 in a continuous arrangement, it has been observed that the non-toothed separation gap between them prevents potential tooth jamming conditions when the step sleeve 224 moves between its high and low step positions.

[0051] With particular reference to Fig. In cases 12, 15, and 16A to 16C, the secondary drive train 16' can comprise the longitudinal shaft 86, a two-speed rear drive module 100', a pair of secondary axle shafts 102L', 102R', and a set of secondary vehicle wheels 104L, 104R. A first end of the longitudinal shaft 86 is coupled to the output gear shaft 60' extending from the two-speed auxiliary power unit 18', while a second end of the longitudinal shaft 86 is coupled for rotation to an input assembly 106' of the two-speed rear drive module 100'. The rear drive module 100' can comprise a housing 108', a second differential 110', a torque transmission device 112', a TTD actuator 114' for controlling the actuation of the torque transmission device 112', a two-speed gear unit 278 comprising a planetary gear arrangement 280 and a gear shift device 282, and a gear shift actuator 284.

[0052] The input assembly 106' can comprise an input gear shaft 116' with a gear 118', a hollow bearing housing 120', and a ring gear 122' attached to a flange portion 156' of the bearing housing 120' and meshing with the gear 118'. The second differential 110' is a planetary assembly that can include an outer gear 180', a sun gear 182', a set of first planet gears 184' meshing with the outer gear 180', a set of second planet gears 186' meshing with the sun gear 182', and a support unit 188 rotatably mounted the first planet gears 184' and the second planet gears 186'. The planet gears are arranged in such a circumferential manner that each of the first planet gears 184' is also in engagement with at least one of the second planet gears 186'.The carrier unit 188' can include a tubular bead 190' configured to be connected to the second axle shaft 102R' via a splined connection 192', while the sun gear 182' can be connected to the second axle shaft 102L' via a splined connection 194'.

[0053] The torque transmission device 112' can comprise an input clutch element 130', which is attached to the ring gear 122 for rotation, an output clutch element 132', and a multi-plate clutch pack 134', which is operationally arranged between them. A clutch bell 166' can be integrally connected to the ring gear 122' and function as the input clutch element 130', while a clutch hub 168' can function as the output clutch element 132'. The clutch pack 134' is arranged between the clutch bell 166' and the clutch hub 168'. The torque transmission device 112' can also include an engagement mechanism 136' which is movable under the control of the TTD actuator 114' based on control signals from the control unit 150 in order to selectively apply a clutch engagement force to the clutch pack 134'.Thus, the rotational force transmitted from the input assembly 106' via the torque transmission device 112' is transferred to the clutch hub 168'. The engagement mechanism 136' can include a pressure piston 170' arranged for sliding movement in a pressure chamber 172', which can be supplied with pressurized fluid by a hydraulically actuated unit associated with the TTD actuator 114'. The engagement mechanism 136' can further include a plurality of circumferentially aligned load pins 266, each having a first end that engages with the pressure piston 170' and a second end that engages with a pressure disk 268. The pressure disk 268 is configured such that the clutch engagement force is exerted on the clutch pack 134'.

[0054] The TTD actuator 114' can be any power-driven device capable of switching the torque transmission device 112' between a first, or "separate," mode and a second, or "connected," mode. The first mode can be established when the engagement mechanism 136' is positioned such that torque is not transmitted from the input clutch element 130' to the output clutch element 132'. The second mode for the torque transmission device 112' can be established when the clutch engagement force exerted by the engagement mechanism 136' causes torque to be transmitted via the clutch assembly 134' to the output clutch element 132'. The TTD actuator 114' can generally be similar to the TTD actuator 114, and the connecting line 140' is used to denote the mechanical or hydraulic connection between the TTD actuator 114' and the engagement mechanism 136'.

[0055] The two-speed gear unit 278 can be operated to establish at least two drive connections with different gear ratios between the output clutch element 132' of the torque transmission device 112' and the second differential 110'. In particular, the planetary gear arrangement 280 can comprise a sun gear 290, which is attached to the clutch hub 168' for rotation via a splined connection 292, a ring gear 294, a plurality of planet gears 296 which mesh with the sun gear 290 and the ring gear 294, and a planet carrier 298 on which the planet gears 296 are rotatably mounted. The planet carrier 298 can be attached for common rotation with the outer gear 180' of the second differential 110'.

[0056] The gearshift mechanism 282 can comprise a first or direct clutch ring 300, which is attached to the clutch hub 168' for rotation, a second or low clutch ring 302, which is fixed to the housing 108' so as not to rotate, a gear shift sleeve 304, and a gear shift fork 306. The load pins 266 are in Fig. 16 shown such that they extend through a plurality of support bores formed by the second coupling ring 302. The gear step sleeve 304 can comprise a set of internal splined teeth 308 that continuously mesh with a set of external splined teeth 310 formed on the ring gear 294 of the planetary gear assembly 280. Thus, the gear step sleeve 304 is coupled to the ring gear 294 for common rotation while being able to perform a bidirectional axial sliding motion on it.The gear-shift sleeve 304 can further comprise a set of first clutch teeth 312, which can be engaged and disengaged with a set of clutch teeth 314 formed on the first clutch ring 300; a set of second clutch teeth 316, which can be engaged and disengaged with a set of clutch teeth 318 formed on the second clutch ring 302; and a set of third clutch teeth 320, which can be engaged and disengaged with a set of clutch teeth 322 formed on a third clutch ring 324, which is fixed for rotation with the outer gear 180'. As will be described in detail below, the sliding motion of the gear-shift sleeve 304 can be performed to establish at least two drive connections with different gear ratios between the clutch hub 168' of the torque transmission device 112' and the outer gear 180' of the second differential 110'.

[0057] The gear step sleeve 304 is in Fig. 16A is shown positioned in a first or high gear position such that its first clutch teeth 312 engage with the clutch teeth 314 on the first clutch ring 300 and its third clutch teeth 320 engage with the clutch teeth 322 on the outer gear 180'. Additionally, the second clutch teeth 316 on the gear sleeve 304 are disengaged by the clutch teeth 318 on the second clutch ring 302. When the gear sleeve 304 is in its first gear position, the gear sleeve 304 directly engages the clutch hub 168' with the outer gear 180'. In addition, the sun gear 290 and the ring gear 294 are coupled by the gear stage sleeve 304 in their first gear stage position in such a way that the planetary gear arrangement 280 is locked against relative rotation and rotates as a unit.Thus, the gear step sleeve 304 establishes a first or drive connection with direct transmission between the output component (the output clutch element 132') of the torque transmission device 112' and the input component (the outer gear 180') of the second differential 110' when it is in its first gear step position.

[0058] The gear step sleeve 304 is used in Fig. 16B is shown positioned in a second or neutral gear position such that its first clutch teeth 312 are disengaged from the clutch teeth 314 on the first clutch ring 300, its second clutch teeth 316 are disengaged from the clutch teeth 318 on the second clutch ring 302, and its third clutch teeth 320 are disengaged from the clutch teeth 322 on the third clutch ring 324. Thus, the output clutch element 132' of the torque transmission device 112' is released from driven engagement with the outer gear 180' of the second differential 110'.

[0059] The gear step sleeve 304 is used in Fig. 16C is shown positioned in a third or low gear position such that the first clutch teeth 312 are disengaged from the clutch teeth 314 on the first clutch ring 300, and that their second clutch teeth 316 are engaged with the clutch teeth 318 on the second clutch ring 302, and that their third clutch teeth 320 are disengaged from the clutch teeth 322 on the third clutch ring 324. Thus, the ring gear 294 is braked against rotation, and the driven rotation of the sun gear 290 (via the output clutch element 132' of the torque transmission device 112') causes the planet carrier 298 to drive the outer gear 180' relative to the sun gear 290 at a reduced speed, thereby establishing a second or reduced drive connection between the output clutch element 132' of the torque transmission device 112' and the outer gear 180' of the second differential 110'.

[0060] The gear actuator 284 can be any type of power-driven mechanism that can be operated to control the axial displacement movement of the gear fork 306, which in turn causes movement of the mode sleeve 304 between its three different gear positions. The gear actuator 284 is shown schematically mounted on the housing 108' of the two-speed rear-drive module 100'. The gear actuator 284 can be a motor-driven transmission device configured to receive control signals from the control unit 150 and convert the rotation of the motor output into a displacement movement of the gear fork 306. The gear fork 306 is in Fig. 16A-16C shown to extend through an opening in the case 108' and to include a projection 330 extending into an annular groove 332 formed on the step sleeve 304.

[0061] In operation, the vehicle 10' can normally be operated in a two-wheel drive mode with a high gear ratio, in which the power take-off unit 18' establishes a high-gear drive connection between the drive system 12 and the primary drivetrain 16', while the rear drive module 100' is decoupled. In particular, the gear shift sleeve 224 and the mode sleeve 246, which are associated with the gear shift mechanism 202 and the disconnect mechanism 54', are as shown in Fig. 14A shown, positioned to establish the 2-Hi mode. When the mode sleeve 246 is in its first operating position, the input shaft 204 is disengaged from the distributor shaft 64' such that substantially all of the torque is transferred from the drive system 12 to the primary drive train 16'. The torque transfer device 112' is held in its first mode to disengage the secondary drive train 20'. While the torque transfer device 112' is operating in its first mode, the gear shift sleeve 304 can be in its high gear position ( Fig. 16A).

[0062] When operation of the motor vehicle 10' in high-gear all-wheel drive mode (AWD-H) is desired or necessary, the control system 22 can be activated to first signal the TTD actuator 114' to switch the torque transmission device 112' to its second mode in order to synchronize the speeds of the primary drive train 16' and the secondary drive train 20'. During synchronization, the control unit 150 signals the disconnect actuator 56' to switch the mode sleeve 246 to its second operating position, while the gear position sleeve 224 remains in its first gear position ( Fig. 14B). This establishes a high-gear, four-wheel drive connection between the drive system 12, the primary drivetrain 16', and the input 106' of the rear drive module 100'. Additionally, the gear actuator 284 can be actuated to hold the gear sleeve 304 in its high-gear position ( Fig. 16A) to hold or move such that the torque supplied via the torque transmission device 112' is transmitted to the second differential 110' with a direct transmission ratio. The TTD actuator 114' can then be controlled to vary the torque transmitted by the torque transmission device 112' to the second vehicle wheels 104L, 104R.

[0063] If, during operation of the vehicle 10' in its AWD-H drive mode, it is desired or determined that improved traction requires operation in a low-gear all-wheel drive mode (AWD-L), the control system 22 functions to coordinate the switching of the power take-off unit 18' to its low-gear four-wheel drive mode and the rear-wheel drive module 100' to its low-gear mode. Specifically, the positions of the mode sleeve 246 and the gear sleeve 224 of the power take-off unit 18' are adjusted to establish this connection. Fig. 14D shows the position of the gear step sleeve 304 of the rear drive module 100' for making this connection in Fig. Figure 16C is shown. Consequently, the low-gear drive connections are established in the power take-off unit 18' and the rear drive module 100'. These low-gear drive connections can be established sequentially or simultaneously based on a suitable control method and can be established in the vehicle 10' in a stationary or immobilized state.

[0064] Finally, for the vehicle 10', by switching the auxiliary power unit 18' into its neutral idle mode ( Fig. 14C) and the rear drive module 100' into its neutral idle mode ( Fig. 16B) a towing mode will be established.

[0065] Referring now to Fig. Figure 17 shows a schematic view of an alternative exemplary embodiment of a two-speed rear-drive module 100", which corresponds to the one described in Fig. The vehicle shown in section 10 can be assigned to the 10'. Essentially, the two-speed rear-wheel drive module 100" is generally similar to the one shown in Fig. 15 and Fig. The two-speed rear-drive module 100' shown in Figure 16 is modified, except that a second bevel-type differential 110" replaces the second planetary differential 110'. Thus, the two-speed gear unit 278 can now be operated to selectively establish drive connections between the output clutch element 132' of the torque transmission device 112' and the second differential housing 124' of the second differential 110'. In particular, the movement of the gear sleeve 304 can be performed to establish drive connections with direct, neutral, or reduction gearing between its three gear positions, between the output component of the torque transmission device 112' and the input component of the second differential 110'.

[0066] The present disclosure relates generally to separable single- and two-speed drive trains for use in all-wheel-drive vehicles. For this purpose, it is desirable to provide power take-off units and rear-drive modules configured to offer a compact arrangement for modular assembly. The single-speed rear-drive modules 100 and 100A from Fig.Figures 8 and 9 illustrate these desirable features such that the second differentials 110 and 110A are shown installed in a cantilevered manner relative to the bell-shaped bearing housing 120 and the meshing ring gear 122 and gear 118. The concentric positioning of the torque transmission devices 112 and 112A relative to the second differentials 110 and 110A provides a compact axial arrangement. Additionally, the bevel-type differential 110 can replace the planetary differential 110A with only minor modifications to the housing 108, thus allowing for product modularity. The two-speed rear-drive modules 100' and 100" also exhibit these desirable features and provide a compact arrangement of the two-speed reduction units between the torque transmission devices and the second differentials.

[0067] While specific aspects have been described in the description and claims and illustrated in the drawings, those skilled in the art understand that various modifications can be made and equivalents for elements and components can be substituted without departing from the scope of the present teaching as defined in the claims. Furthermore, the combining and adapting of features, elements, components, and / or functions between different aspects of the present teaching is expressly considered herein, so that a person skilled in the art understands from the present teaching that features, elements, components, and / or functions of one aspect of the present teaching can be incorporated into another aspect, as applicable, unless otherwise described above.Furthermore, many modifications can be made to adapt the present teaching to a specific situation, configuration, or material without altering its essential scope. Therefore, it is intended that the present teaching is not limited to the specific aspects illustrated by the drawings and described in the description and claims as the best mode currently considered for carrying out the present teaching, but rather that its scope encompasses many aspects and examples that follow within the preceding description and the appended claims.

Claims

[1] Rear drive module (100, 100', 100", 100A) having a case (108, 108'), a gear (118, 118') which is mounted in the housing (108, 108') for rotation about a first axis, a ring gear (122, 122') which is in meshing engagement with the gear (118, 118') and can rotate about a second axis, wherein the ring gear (122, 122') is supported for rotation relative to the housing (108, 108') by a pair of tapered roller bearing assemblies (158) which are arranged laterally and on the same side of the ring gear (122, 122') along the second axis, a pair of axle shafts (102L, 102R, 102L', 102R'), and a differential (110, 110', 110", 110A) which is housed in the casing (108, 108') and is arranged driving between the axle shafts (102L, 102R, 102L', 102R') and the ring gear (122, 122'), wherein the differential (110, 110', 110", 110A) has a pair of output elements (128, 182, 182', 188, 188'), wherein each of the output elements (128, 182, 182' 188, 188') is driven by a corresponding one of the axle shafts (102L, 102R, 102L', 102R'), wherein the rear drive module (100, 100', 100", 100A) also has a torque transmission device (112, 112', 112A) which is coupled to the differential (110, 110', 110", 110A) and can be used to disengage the gear (118, 118') from the axle shafts (102L, 102R, 102L', 102R'), wherein the torque transmission device (112, 112', 112A) is arranged between the ring gear (122, 122') and an input element (124, 124', 180, 180') of the differential (110, 110', 110", 110A), and either a) the differential (110', 110A) has a planetary gear set (184, 184') and an output element (168', 168A) of the torque transmission device (112', 112A) is coupled to an outer gear (180, 180') of the planetary gear set (184, 184') for common rotation, or b) the differential (110, 110") has a pair of output side gears (128) which are accommodated in a differential housing (124, 124') and an output element (168, ) of the torque transmission device (112, 112', 112A) is coupled to the differential housing (124, 124') for common rotation. [2] Rear drive module (100, 100', 100", 100A) according to claim 1, wherein the housing (108, 108') comprises a housing body and a gear holder, wherein the housing body defines a cavity in which the differential (110, 110', 110", 110A) is received, wherein the gear (118, 118') is rotatably mounted on the gear holder, wherein the gear holder is detachably coupled to the housing body. [3] Rear drive module (100, 100', 100", 100A) according to claim 1, wherein the ring gear (122, 122') has a stub on which the tapered roller bearing groups (158) are received, wherein the stub has a set of threads, and wherein a nut (160) engages thread-like with the set of threads and bears against an inner bearing ring of an outer one of the tapered roller bearing groups (158). [4] Rear drive module (100, 100', 100", 100A) according to claim 1, wherein the torque transmission device (112, 112', 112A) is a friction clutch. [5] Rear drive module (100, 100', 100", 100A) according to claim 4, wherein the housing (108, 108') comprises a housing body and a cover which is detachably coupled to the housing body, wherein the differential (110, 110', 110" 110A) is received in a cavity of the housing body, and wherein a piston (170, 170') of the friction clutch is received in an annular cavity defined by the cover. [6] Rear drive module (100, 100', 100", 100A) according to claim 5, wherein a bearing is arranged between the cover and one of the output elements (128, 182, 182' 188, 188').

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