Interruptible drivetrain for an all-wheel drive vehicle

Abstract

A vehicle powertrain comprising: a drive shaft rotatable about a first axis (204); a range sleeve (224) which is concentric with the drive shaft, wherein the range sleeve is not rotatable but slidably coupled to the drive shaft and is movable along the first axis between a first range sleeve position and a second range sleeve position; a mode sleeve (246) which is concentric with the drive shaft, wherein the mode sleeve is displaceable along the first axis between a first mode sleeve position and a second mode sleeve position; a planetary gear arrangement (200) comprising a planet carrier (212), a sun gear (208) and a plurality of planet gears (210) rotatably mounted on the planet carrier and meshing with the sun gear; a differential unit (30') comprising a differential housing (38') and a differential gear set, wherein the differential housing is coupled to the planet carrier (212) for common rotation about the first axis, the differential gear set is arranged in the differential housing and includes a pair of differential output elements (42'); an axle shaft (34L') coupled for rotation to one of the differential output elements (42'), the axle shaft extending through the sun gear (208) and the drive shaft; and a transmission gear arrangement (52') with an input (64') and an output (60'), wherein the output is rotatable about a second axis; wherein the placement of the range sleeve (224) in the first range sleeve position couples the planet carrier (212) with the drive shaft (204) for common rotation and wherein the placement of the range sleeve in the second range sleeve position couples the sun gear (208) with the drive shaft for common rotation; wherein the arrangement of the mode sleeve (246) in the first mode sleeve position, when the range sleeve (224) is in the first range sleeve position, decouples the range sleeve from the input (64') to allow a relative rotation between the range sleeve and the input, and wherein the arrangement of the mode sleeve in the second mode sleeve position, when the range sleeve is in the first range sleeve position, couples the range sleeve to the input for a common rotation.

Description

REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Patent Application No. 13 / 470,941 (published as US 2013 / 0 303 326 A1), filed May 14, 2012, the disclosure of which is hereby incorporated by reference in its entirety. AREA

[0002] The present disclosure relates generally to all-wheel drive vehicles, and more particularly to interruptible single-speed and multi-speed drivetrains for all-wheel drive vehicles. BACKGROUND

[0003] This section provides background information related to the present disclosure that is not necessarily prior art.

[0004] Many modern self-propelled vehicles, such as crossovers, are available with an all-wheel drive (AWD) drivetrain based on a front-wheel drive (FWD) architecture. This optional drivetrain arrangement allows drive torque to be selectively and / or automatically transferred from the propulsion system to both the primary (i.e., front) driveline and the secondary (i.e., rear) driveline to provide improved traction when the vehicle is operated in adverse weather and off-road driving conditions. Such AWD vehicles are necessarily equipped with a much more complex drivetrain, which, in addition to the primary driveline, must include the additional components associated with the secondary driveline, such as an output drive unit and a propshaft.

[0005] Document US 2012 / 0 234 120 A1 discloses a power transmission device comprising a first rotary element, a second rotary element, and a coupling device adapted to connect and disconnect a power transmission between the first rotary element and the second rotary element. Furthermore, the power transmission device comprises an actuator adapted to actuate the coupling device, wherein the actuator is an electromagnetic actuator having a ring shape. A portion of the first rotary element or the second rotary element and a rotation axis of the first rotary element or the second rotary element extends through a radial interior of the ring-shaped actuator.

[0006] From document US 2012 / 0 083 380 A1, a vehicle drive system is known that is capable of selectively providing all-wheel drive and a single-drive axle mode. The drive system includes a front drive unit with a planetary gear train having a grounded ring gear and a sun gear driven by the transaxle's drive spool via an input shaft, and a differential selectively coupled by a dog clutch to either the sun gear or the planetary carrier, or to neither, to thereby selectively provide both an available low range and front axle decoupling.

[0007] In an attempt to minimize driveline losses (i.e., drag, friction, inertia, and oil splash) associated with the secondary driveline being retracted when no drive torque is being applied to it, it is known to incorporate an interrupt system configured to decouple secondary driveline components, such as the rear wheels or rear differential, from the rest of the secondary driveline. In this regard, there remains a need in the art to develop improved interruptible drivelines for use in AWD vehicles.

[0008] The object is achieved according to the invention by a vehicle drive train having the features of patent claim 1 and by a vehicle drive train having the features of patent claim 10. Furthermore, the object is achieved according to the invention by a rear-wheel drive module having the features of patent claim 21 and by a rear-wheel drive module having the features of patent claim 32. SUMMARY

[0009] It is an aspect of the present teachings to provide an interruptible secondary driveline assembly for use with all-wheel drive vehicles, comprising a single-gear output unit having an interrupt mechanism, a single-gear rear drive module having a torque transmitting device providing an interrupt function, a speed synchronizing function, and a torque preset function, and a control system for controlling actuation of the interrupt mechanism and the torque transmitting device.

[0010] It is a further aspect of the present teachings to provide an interruptible secondary driveline assembly for use with all-wheel drive vehicles, comprising a two-speed output unit having an interrupt mechanism and a range shift mechanism, a two-speed rear drive module having a torque transfer device and a range shift mechanism, and a control system for controlling coordinated actuation of the two-speed output unit and the two-speed rear drive module.

[0011] According to these and other aspects of the present teachings, a four-wheel drive vehicle may include a drive system, a primary driveline, a power switching mechanism, a secondary driveline, and a control system. The drive system may include a prime mover and a transmission having an output. The primary driveline is driven by the transmission output and is operable to direct rotational power from the prime mover to a pair of primary vehicle wheels. The power switching mechanism is operable in one of an intermittent mode and an engaged mode under the control of the control system. The power switching mechanism is operable in its engaged mode to direct rotational power from the transmission output to the secondary driveline. The secondary driveline may include a rear drive module and a propshaft connecting an output of the power switching mechanism to an input of the rear drive module.The rear-drive module may include a secondary differential connecting a pair of axleshafts to a pair of secondary vehicle wheels, and a torque-transmitting device disposed between the input and the secondary differential. The torque-transmitting device is operable in one of an intermittent mode and an engaged mode under the control of the control system. The torque-transmitting device is operable in its engaged mode to transfer rotational power transmitted from the power switching mechanism to the secondary differential. When the power switching mechanism and the torque-transmitting device are in their intermittent mode, rotational power is transmitted only to the primary vehicle wheels.The torque-transfer device is operable in its intermittent mode to prevent the secondary vehicle wheels and secondary differential from backdriving the rear drive module input, the propshaft, and the power shift mechanism output. The power shift mechanism is operable in its intermittent mode to prevent the transmission output from driving the power shift mechanism output and the propshaft.

[0012] In addition to the above, a four-wheel drive vehicle of the present teachings may also include a two-speed power shift mechanism and a two-speed rear-drive module. The two-speed power shift mechanism is still operable in its intermittent and connected mode, but further includes a planetary reduction mechanism and a range shift mechanism operably disposed between the transmission output and a primary differential driving the vehicle's primary wheels. The power shift mechanism may establish a two-wheel high-range drive connection, a four-wheel high-range drive connection, and a four-wheel low-range drive connection between the transmission output and the primary differential.The two-speed rear drive module is still operable in its intermittent and connected mode, but further includes a planetary reduction mechanism and a range shift mechanism disposed between an output of the torque transfer device and the secondary differential. The rear drive module can establish a high-range drive connection and a low-range drive connection between the output of the speed transfer device and an input to the secondary differential. The control system is operable to coordinate the activation of the two-speed power shift mechanism and the two-speed rear drive module.

[0013] The following embodiments are also subject of the present invention: Embodiment 1:

[0014] A drivetrain for a four-wheel drive motor vehicle, the drivetrain comprising: a primary driveline comprising a first differential, the primary driveline being adapted to drive a pair of first vehicle wheels, the first differential having a first differential housing, a power shift mechanism including an input shaft adapted to receive rotational power from a drive system, a two-speed range unit disposed between the input shaft and the first differential and operable in a first range mode to connect the input shaft and the first differential case for common rotation, and operable in a second range mode to establish a reduced speed ratio drive connection between the input shaft and the first differential case, an output pinion shaft, an interrupt mechanism operable in a connected mode to enable the transmission of rotational power between the input shaft and the output pinion shaft, and operable in an interrupted mode to prevent the transmission of rotational power between the input shaft and the output pinion shaft; and a second drivetrain comprising a propeller shaft and a rear-drive module, the rear-drive module having a second differential, a drive pinion, an output shaft, a torque-transmitting device, and a second two-speed range unit, the second differential being adapted to drive a group of second vehicle wheels and having a second differential case, the drive pinion shaft being coupled to the output pinion shaft of the power shift mechanism through the propeller shaft, the torque-transmitting device operable in a first mode to enable the transmission of rotational power between the drive pinion shaft and the output pinion shaft and operable in a second mode to prevent the transmission of rotational power between the drive pinion shaft and the output pinion shaft,wherein the second two-speed range unit is arranged between the output shaft and the second differential and is operable in a first range mode to establish a drive connection at a first speed ratio between the output shaft and the second differential case, and is operable in a second range mode to establish a drive connection at a second speed ratio between the output shaft and the second differential case. Embodiment 2:

[0015] The drivetrain of embodiment 1, wherein the power shift mechanism is an output unit including a transfer gear assembly that drives the output pinion shaft, the two-speed range unit including a planetary gear assembly and a range sleeve, the planetary gear assembly including 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 rotatably supporting the planet gears and fixed for rotation with the first differential case, the range sleeve connected for common rotation with the input shaft and axially movable between a first range position in which the range sleeve connects the input shaft to the planet carrier and a second range position in which the range sleeve connects the input shaft to the sun gear. Embodiment 3:

[0016] The powertrain of embodiment 2, wherein the interrupt mechanism comprises a mode sleeve connected to the range sleeve for common rotation and sliding movement between a first operating position and a second operating position, the mode sleeve connecting the transfer gear assembly to the range sleeve when in its first operating position, and the mode sleeve being disengaged from the transfer gear assembly when the mode sleeve is in its second operating position. Embodiment 4:

[0017] The drivetrain of embodiment 3, wherein the range sleeve surrounds a portion of the drive shaft and is axially movable thereon between its first and second range positions, wherein the transfer gear assembly includes a transfer shaft surrounding a portion of the drive shaft and the range sleeve, and wherein the mode sleeve surrounds a portion of the range sleeve and is axially movable thereon between its first operating position and its second operating position. Embodiment 5:

[0018] The powertrain of embodiment 4, wherein the transmission gear assembly includes a first helical gear fixed on the transmission shaft, a second helical gear fixed on a stub shaft and meshing with the first helical gear, a hypoid gear fixed on the stub shaft, and a drive pinion gear meshing with the hypoid gear and fixed for rotation with the output pinion shaft. Embodiment 6:

[0019] The drivetrain of embodiment 3, wherein the rear drive module further comprises a hypoid gear driven by the input pinion shaft and a pulley driven by the hypoid gear, wherein the torque-transmitting device is a friction clutch disposed between the pulley and the output shaft, and wherein the second two-speed range unit comprises a second planetary gear assembly and a second range sleeve, the second planetary gear assembly comprising a second non-rotating ring gear, a second sun gear fixed for rotation with the output shaft, a plurality of second planet gears meshing with the second ring gear and the second sun gear, and a second planet carrier rotatably supporting the second planet gears,wherein the second range sleeve is connected for common rotation with the second differential case and is axially movable at least between a first and a second range position for establishing the first and second range modes., Embodiment 7:

[0020] A drive train according to embodiment 6, wherein positioning the second range sleeve in its first range position connects the output shaft to the second differential housing, and wherein positioning the second range sleeve in its second range position connects the second planet carrier to the second differential housing. Embodiment 8:

[0021] The drivetrain of embodiment 7, wherein the second range sleeve is selectively positionable in a third range position to establish a locking mode for the second differential. Embodiment 9:

[0022] The driveline of embodiment 7, wherein a two-wheel high-range drive mode for the motor vehicle is established when the mode sleeve is in its second operating position, the range sleeve is in its first range position, and the torque-transmitting device is in its second mode, whereby substantially all rotational power is transmitted through the primary driveline to the first vehicle wheels, and wherein the rear drive module drive pinion shaft and the propshaft are not driven reversely by the second differential. Embodiment 10:

[0023] The powertrain of embodiment 7, wherein an all-wheel high-range drive mode for the motor vehicle is established when the mode sleeve is in its first operating position, the range sleeve is in its first range position, the torque-transmitting device is actuated in its first mode, and the second range sleeve is in its first range position. Embodiment 11:

[0024] The powertrain of embodiment 7, wherein an all-wheel low-range drive mode for the motor vehicle is established when the mode sleeve is in its first operating position, the range sleeve is in its second range position, the torque-transmitting device is actuated in its first mode, and the second range sleeve is in its second range position. Embodiment 12:

[0025] The powertrain of embodiment 1, wherein a two-wheel high-range drive mode is established for the motor vehicle when the interrupt mechanism is operable in its interrupt mode, the two-speed range unit is operable in its first range mode, and the torque transmitting device is operable in its second mode, whereby the second differential does not drive the drive pinion shaft and the propshaft in reverse. Embodiment 13:

[0026] The powertrain of embodiment 1, wherein an all-wheel drive high-range drive mode is established for the motor vehicle when the disconnect mechanism is operable in its connect mode, the two-speed range unit is operable in its first range mode, the torque-transmitting device is operable in its first mode, and the second two-speed range unit is operable in its first range mode. Embodiment 14:

[0027] The powertrain of embodiment 1, wherein an all-wheel low-range drive mode is established for the motor vehicle when the interrupt mechanism is operable in its connect mode, the two-speed range unit is operable in its two-range mode, the torque-transmitting device is operable in its first mode, and the second two-speed range unit is operable in its second range mode. Embodiment 15:

[0028] A drivetrain for a four-wheel drive motor vehicle, the drivetrain comprising: a primary driveline comprising a first differential adapted to drive a pair of first vehicle wheels; a power shift mechanism having an input shaft adapted to receive rotational power from a drive system, a first range unit having a first input, a second input, an output driving the first differential, and a first range shift mechanism operable in a first range mode to establish a high-range drive connection between the input shaft and the first input and operable in a second range mode to establish a low-range drive connection between the input shaft and the second input, an output pinion shaft, and an interrupt mechanism operable in a connected mode to establish a drive connection between the input shaft and the output pinion shaft and operable in an interrupted mode to disconnect the drive connection between the input shaft and the output pinion shaft; and a secondary driveline comprising a second differential adapted to drive a pair of second vehicle wheels, a drive pinion shaft connected by a propeller shaft to the output pinion shaft of the power shift mechanism, an output shaft, a torque-transmitting device operable in a connected mode to establish a driving connection between the drive pinion shaft and the output shaft and operable in an intermittent mode to release the driving connection between the drive pinion shaft and the output shaft, and a second range unit having a first input, a second input, an output driving the second differential, and a second range shift mechanism operable in a first range mode to establish a high-range driving connection between the output shaft and the first input of the second range unit.and operable in a second range mode to establish a low-range drive connection between the output shaft and the second input of the second range unit., Embodiment 16:

[0029] The powertrain of embodiment 15, wherein the first range unit comprises a first planetary gear arrangement having a non-rotating ring gear, a sun gear, a plurality of planet gears meshing with the ring gear and the sun gear, and a carrier rotatably supporting the planet gears and connected to a first differential case of the first differential, wherein the first range shifting mechanism comprises a first range sleeve connected for common rotation with the input shaft and axially movable between first and second range positions, and wherein the first range sleeve is operable in its first range position to connect the input shaft to the planet carrier and operable in its second range position to connect the input shaft to the sun gear. Embodiment 17

[0030] The drivetrain of embodiment 16, wherein the interrupt mechanism comprises a mode sleeve connected to the range sleeve for common rotation and sliding movement between a first operating position and a second operating position, the mode sleeve being operable in its first operating position to connect the first range sleeve for common rotation with the output pinion shaft, and the mode sleeve being operable in its second operating position to disengage the first range sleeve from drive connection with the output pinion shaft. Embodiment 18:

[0031] The drivetrain of embodiment 17, wherein the rear drive module further comprises a hypoid gear driven by the input pinion shaft and a pulley driven by the hypoid gear, wherein the torque-transmitting device is a friction clutch disposed between the pulley and the output shaft, and wherein the second range unit comprises a second planetary gear arrangement having a second non-rotating ring gear, a second sun gear fixed for rotation with the output shaft, a plurality of second planet gears meshing with the second ring gear and the second sun gear, and a second carrier rotatably supporting the second planet gears, wherein the second differential comprises a second differential case, and wherein the second range shifting mechanism comprises a second range sleeve,which is connected for common rotation with the second differential housing and is axially movable at least between a first and a second range position for establishing the first and second range modes., Embodiment 19:

[0032] The driveline of embodiment 18, wherein the second range sleeve is operable in its first range position to connect the output shaft to the second differential case, and wherein the second range sleeve is operable in its second range position to connect the second carrier to the second differential case. Embodiment 20:

[0033] The drivetrain of embodiment 19, wherein the second range sleeve is operable in a third range position to establish a locking mode for the second differential.

[0034] Further areas of applicability will become apparent from the 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 the present disclosure.

[0035] The drawings described herein serve solely to illustrate selected embodiments and are not intended to limit the scope of the present disclosure in any way. Similar or identical elements are given the same reference numerals throughout the figures.

[0036] The present invention will be better understood from the detailed description and the accompanying drawings, in which: Fig. 1 is a schematic view of a motor vehicle equipped with an interruptible all-wheel drive system constructed in accordance with the present teachings; Fig. 2 is a schematic representation of a single-gear output unit associated with the interruptible all-wheel drive system of Fig. 1 is assigned; Fig. 3 to Fig. 5 are perspective views of a single-gear output unit based on the Fig. 2, with its housing structure removed for clarity, and constructed in accordance with the present teachings; Fig. 6 is a cross-sectional view of the single-gear output unit, taken generally along line 6-6 of Fig. 5 created; Fig. Figure 7 is a schematic view of a single-gear rear-wheel drive module associated with the interruptible all-wheel drive system of Fig. 1 is assigned; Fig. 8 to 10 are perspective views of a rear-wheel drive module with one gear, based on the Fig. 7, with and without its housing structure, and constructed in accordance with the present teachings; Fig. 11 is a cross-sectional view of the rear drive module with a gear, taken generally along line 11-11 of Fig. 10 created; Fig. 12 is a schematic view of a motor vehicle equipped with another configuration of an interruptible all-wheel drive system constructed in accordance with the present teachings. Fig. 13 is a schematic representation of a two-speed output unit associated with the interruptible all-wheel drive system of Fig. 12 is assigned; Fig. 14 is an exploded perspective view of a two-speed output unit based on the Fig. 13, constructed in accordance with the present teachings; Fig. 15 a cross-sectional view of the Fig. 14 shown two-speed output unit; Fig. 16a to 16d partial cross-sectional views of the Fig. 15, with its mode and range shifting components positioned to define a two-wheel high-range (2-Hi) mode, a four-wheel high-range (4-Hi) mode, a neutral mode, and a four-wheel low-range (4-Low) mode, respectively. Fig. 17a to 17d are schematic views of a two-speed rear-wheel drive module associated with the interruptible all-wheel drive system of Fig. 12, with its range switching components positioned to define a high range (H) mode, a neutral (N) mode, a low range (L) mode, and a low range lock (LOCK) mode, respectively; Fig. 18 to 21 are perspective views of a two-speed rear-wheel drive module, based on the Fig. 17a to 17d, with and without its housing structure, and constructed in accordance with the present teachings; Fig. 22 is a cross-sectional view taken generally along line 22-22 of Fig. 21 created; and Fig. 23 is a partial cross-sectional view of an alternative exemplary embodiment of a rear two-speed drive module adapted for use with the interruptible all-wheel drive system of Fig. 12 is configured. DETAILED DESCRIPTION

[0037] The following exemplary embodiments are provided so that the present disclosure will fully and completely convey the scope of the invention to those skilled in the art. Numerous specific details are set forth, such as examples of specific components, devices, and schematic configurations, in order to provide a thorough understanding of exemplary embodiments of the present disclosure. However, those skilled in the art will appreciate that these specific details need not be implemented, that the exemplary embodiments may be embodied in a variety of ways, and that nothing herein is intended to limit the scope of the present invention.

[0038] In relation to Fig. Referring to Figure 1 of the drawings, a motor vehicle constructed in accordance with the teachings of the present disclosure is shown schematically and indicated generally by reference numeral 10. The vehicle 10 may include a propulsion system 12 and a driveline 14, which may include a primary driveline 16, a power switching mechanism 18, a secondary driveline 20, and a control system 22. In various aspects of the present teachings, the primary driveline 16 may be a front-mounted driveline, while the secondary driveline 20 may be a rear-mounted driveline.

[0039] The drive system 12 may include a prime mover 24, such as an internal combustion engine or an electric motor, and a transmission 26, which may be any type of ratio-changing mechanism, e.g., a manual, automatic, or continuously variable transmission. The prime mover 24 is operable to provide rotational power to the primary driveline 16 and the power-transmitting mechanism 18.

[0040] With additional reference to Fig. 2, the primary driveline 16 may include a primary or first differential 30 having an input member 32 driven by an output member (not shown) of the transmission 26. In the particular construction shown, the first differential 30 is configured as part of the transmission 26, a type commonly referred to as a transaxle and typically used in front-wheel drive vehicles. The primary driveline 16 may further include a pair of first axleshafts 34L, 34R that may connect output components of the first differential 30 to a set of first vehicle wheels 36L, 36R.The first differential 30 may include a first differential case 38 rotatably driven by the input member 32, at least a pair of first drive pinions 40 rotatably driven by the first differential case 38, and a pair of first side gears 42 meshing with the first drive pinions 40 and interconnected to drive the first axle shafts 34L, 34R.

[0041] Further with reference to Fig. 2, the power shift mechanism 18, hereinafter referred to as a power take-off unit (PTU), may generally include a housing 46, an input 48 connected for common rotation with the first differential case 38 of the first differential 30, an output 50, a transfer gear assembly 52, an interrupt mechanism 54, and an interrupt actuator 56. The input 48 may include a tubular input shaft 58 rotatably supported by the housing 46 and concentrically surrounding a portion of the first axle shaft 34R. A first end of the input shaft 58 may be connected for rotation with the first differential case 38. The output 50 may include an output pinion shaft 60 rotatably supported by the housing 46 and having an input pinion 62. The transmission gear assembly 52 may include a distributor hollow shaft 64, a helical gear set 66, and a hypoid gear 68 that meshes with the drive pinion 62.The distributor shaft 64 concentrically surrounds a portion of the first axle shaft 34R and is rotatably supported by the housing 46. The helical gear set 66 may include a first helical gear 70 fixed for rotation with the distributor shaft 64 and a second helical gear 72 meshing with the first helical gear 70. The second helical gear 72 and the hypoid gear 68 are integrally formed with, or fixed for common rotation with, a stub shaft 74 rotatably supported in the housing 46.

[0042] The interrupt mechanism 54 may include any type of clutch, interrupter, or coupling device that can be used to selectively transfer rotational power from the drive system 14 to the secondary driveline 20. In the particular example provided, the interrupt mechanism 54 is configured as a dog clutch. The dog clutch may include a set of external splines 76 formed on a second end of the drive shaft 58, a set of external dog splines 78 formed on the transfer shaft 64, a mode sleeve 80 having internal splines 82 that constantly mesh with the external splines 76 on the drive shaft 58, and a shift fork 84 operable to axially translate the shift sleeve 80 between a first operating position and a second operating position.Although shown schematically as a non-synchronized dog clutch, it is to be understood that the interrupt mechanism 54 may comprise a synchronized dog clutch if such a configuration is desired.

[0043] The mode sleeve 80 is shown in its first operating position, indicated by a "2WD" guideline, with the inner splines 82 on the mode sleeve 80 disengaged from the outer dog teeth 78 on the distributor shaft 64. Thus, the input shaft 58 is decoupled from driven engagement with the distributor shaft 64. Therefore, no rotational power is transmitted from the drive system 12 to the transfer gear assembly 52 and the output pinion shaft 60 of the output unit 18. When the mode sleeve is in its second operating position, indicated by an "AWD" guideline, its splines 82 are engaged with both the outer splines 76 on the input shaft 58 and the outer clutch splines 78 on the distributor shaft 64.Accordingly, the mode sleeve 80 establishes a driving connection between the input shaft 58 and the transfer shaft 64 such that rotational power is transmitted from the drive system 12 via the output unit 18 to the output pinion shaft 60. As discussed below, the output pinion shaft 60 is connected to the secondary driveline 20 via a propshaft 86.

[0044] The interrupt actuator 56 may comprise any type of actuator mechanism operable to axially move the shift fork 84, which in turn causes a simultaneous axial translation of the mode sleeve 80 between its two different operating positions. The interrupt actuator 56 is shown mounted on the housing 46 of the output unit 18. The interrupt actuator 56 may be a power-operated mechanism that receives control signals from the control system 22 and may include, for example, hydraulically actuated, pneumatically actuated, or electromechanically actuated arrangements.

[0045] As mentioned, Fig. 2 schematically shows the components that can be assigned to the output unit 18. With regard to Fig. 3 through 6, a more definitive structural configuration of such components associated with an exemplary embodiment of the output unit 18 is now provided. In particular, these figures show the components in an assembled state, with the housing 46 not shown for clarity. Each of the input shaft 58, transfer shaft 64, stub shaft 74, and output pinion shaft 60 is shown with suitable bearings disposed thereon for rotatable support within or from the housing 46, respectively. The interrupt actuator 56 is shown as a self-supporting power-driven unit 88 from which the shift fork 84 extends. The power-driven unit 88 may include an electric motor and a transmission drive unit configured to convert the rotation of the engine output into translational motion of the shift fork 84.External splines 90 are provided on one end of the first axle shaft 34R to facilitate spline engagement with its respective first side gear 42 of the first differential 30. Similarly, external splines 92 are provided on the first end of the input shaft 58 to facilitate spline engagement with a meshing portion of the first differential case 38.

[0046] Especially with regard to Fig. 1 and Fig. 7, the secondary driveline 20 may include the propshaft 86, a rear drive module (RDM) 100, a pair of second axle shafts 102L, 102R, and a set of second vehicle wheels 104L, 104R. A first end of the propshaft 86 may be connected for rotation with the output pinion shaft 60 extending from the output unit 18, while a second end of the propshaft 86 may be connected for rotation with an input 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-transmitting device (TTD) 112 generally configured and arranged to selectively couple and transmit rotational power from the input 106 to the second differential 110, and a TTD actuator 114.The input 106 may include a drive pinion shaft 116 having a drive pinion 118, a hollow roller 120, and a hypoid gear 122 mounted for rotation with the roller 120 and meshing with the drive pinion 118. The second differential 110 may include a second differential case 124, at least a pair of second drive pinions 126 rotatably driven by the second differential case 124, and a pair of second output side gears 128 meshing with the second drive pinions 126. The second output side gears 128 are connected for rotation with the inboard ends of the second axle shafts 102L, 102R.

[0047] The torque-transmitting device 112 may include any type of clutch or coupling device that can be used to selectively transmit rotational power from the input 106 to the second differential 110. In the example shown, the torque-transmitting device 112 is a multi-plate friction clutch that may include an input clutch member 130 driven by the roller 120, an output clutch member 132 connected for rotation to the second differential case 124, a multi-plate clutch pack 134 having overlapping friction plates disposed between the input and output clutch members, and an engagement member 136 movable to selectively apply a clutch engagement force to the clutch pack 134.An elongated hollow clutch output shaft 138 may connect the output clutch member 132 for common rotation with the second differential case 124 and is configured to surround a portion of the second axle shaft 102R. The TTD actuator 114 is provided to generate translational movement of the engagement member 136 relative to the clutch pack 134 and may be controlled by control signals from the control system 22.

[0048] A first, or "disengaged" mode can be established for the torque-transmitting device 112 when the engagement member 136 is positioned so that rotational power is not transferred from the input clutch member 130 to the output clutch member 132. In this "disengaged" mode, the second vehicle wheels 104L, 104R, the second axle shafts 102L, 102R, the second differential 110, the clutch output shaft 138, and the output clutch member 132 are decoupled from the input 106 of the rear drive module 100. Therefore, rotation of these components due to the rolling motion of the second vehicle wheels does not result in "backdriving" the propshaft 86 and the components of the output unit 18.

[0049] A second or "linked" mode for the torque-transmitting device 112 may be established when the clutch engagement force applied by the engagement member 136 to the clutch pack 134 causes a transfer of torque from the input 106 to the clutch output shaft 138, to be routed to the rear wheels 104L, 104R via the second differential 110. Additionally, a "torque bias" function may also be provided in the linked mode, as variable control of the magnitude of the clutch engagement force applied to the clutch pack 134 may alter the distribution ratio of torque transmitted from the drive system 12 to the primary driveline 16 and the secondary driveline 20.The torque transmitting device 112 may therefore be configured or controlled to have slippage or to be cyclically engaged or disengaged as needed to preset the available drive torque while establishing the drive connection between the input 106 and the second differential 110.

[0050] The TTD actuator 114 may be any power-driven device capable of switching the torque-transmitting device 112 between its first and second modes and adaptively adjusting the strength of the clutch engagement force that the engaging member 136 exerts on the clutch pack 134. Thus, the TTD actuator 114 may include, for example, an electromagnetic or motor-driven ball screw, ball ramp, or other cam actuation system with a mechanical connection, indicated by guide line 140, to the engaging member 136. Alternatively, the TTD actuator 114 may include a hydraulic actuation system capable of adjusting the position of the engaging member 136 relative to the clutch pack 134 by adjusting the fluid pressure, also indicated by guide line 140, delivered to a pressure chamber.

[0051] The tax system 22 is in Fig. 1 and includes a control unit 150, a group of first sensors 152, and a group of second sensors 154. The group of first sensors 152 may be arranged in the motor vehicle 10 to sense a vehicle parameter and generate a first sensor signal as needed. The vehicle parameter may be associated with any combination of the following: vehicle speed, yaw rate, steering angle, engine torque, wheel speeds, shaft speeds, lateral acceleration, longitudinal acceleration, throttle position, and gear position, but are not limited thereto. The group of second sensors 154 may be configured to sense a driver-initiated input to one or more on-board devices and / or systems in the vehicle 10 and generate a second sensor signal as needed. For example, the motor vehicle 10 may be equipped with a sensor associated with a mode selection device, e.g.a switch associated with a push button or lever that senses when the vehicle operator has selected between vehicle operation in a two-wheel drive (FWD) mode and an all-wheel drive (AWD) mode. Switching of vehicle systems such as the windshield wipers, defroster, and / or heating system, for example, may also be used by control unit 150 to evaluate whether the motor vehicle 10 should automatically switch between FWD and AWD modes.

[0052] As mentioned, Fig. 7 schematically shows the components that can be assigned to the rear drive module 100. With regard to Fig. 8 to 11, a more definitive structural configuration of such components associated with an exemplary embodiment of the rear drive module 100 is shown. These views show the components in an assembled state, with and without the housing 108. Each of the drive pinion shaft 116, the second axle shafts 102L, 102R, the second differential housing 124, the pulley 120, and the clutch output shaft 138 are shown with suitable bearings disposed thereon for rotatable support within or from the housing 108, respectively. Fig. 11 specifically, the roller 120 is fixed for rotation via a splined connection 156 to an annular sleeve portion 158 of a clutch hub 160 defining the input clutch member 130. Similarly, the output clutch member 132 may be a clutch drum 162 connected for rotation to a first end of the clutch output shaft 138 via a splined connection 164. The opposite end of the clutch output shaft 138 is fixed via a splined connection 166 to a tubular hub portion 168 of the second differential case 124. The engagement member 136 may be an application piston disposed in the pressure chamber supplied with pressurized hydraulic fluid by a hydraulically operated unit 169 associated with the TTD actuator 114.The hydraulically operated unit 169 may include a motor-driven fluid pump 170, an accumulator 172, and related hydraulic components, all of which are located near or attached to the housing 108.

[0053] With reference to Fig. 1, Fig. 2 and Fig. 7, the vehicle 10 may normally be operated in two-wheel drive (FWD) mode, in which the output unit 18 and the rear drive module 100 are both disengaged. More specifically, the mode sleeve 80 of the interrupt mechanism 54 is moved to its first (2WD) operating position by the interrupt actuator 56, such that the input shaft 58 is decoupled from the transfer shaft 64. Therefore, substantially all of the power provided by the drive system 12 is transferred to the primary driveline 16. Likewise, the torque-transmitting device 112 may be shifted to and maintained in this first (interrupted) mode, such that the input 106, propshaft 86, drive pinion shaft 60, and transfer gear assembly 52 in the output unit 18 are not retracted due to the rolling motion of the second vehicle wheels 104.

[0054] When it is desired or required to operate the motor vehicle 10 in all-wheel drive (AWD) mode, the control system 22 may be activated via a suitable input, which, as noted, may include a driver-requested input (via the mode selector) 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 initially signals the TTD actuator 114 to shift the torque-transmitting device 112 into its second (connected) mode. More specifically, the control unit 150 controls the operation of the TTD actuator 114 such that the actuating member 136 is moved and a clutch engagement force is applied to the clutch pack 134 sufficient to synchronize the speed of the secondary driveline 20 with the speed of the primary driveline 16.During speed synchronization, the control unit 150 signals the actuator 56 to cause the mode sleeve 80 in the output unit 18 to move from its first operating position to its second operating position. With the mode sleeve 80 in its second operating position, torque is transferred from the drive system 12 to the primary driveline 16 and the secondary driveline 20. It will be appreciated that subsequently controlling the magnitude of the clutch engagement force generated by the torque-transmitting device 112 enables torque bias in the clutch pack 134 to control the torque distribution ratio transferred from the drive system 12 to the primary driveline 16 and the secondary driveline 20.

[0055] With reference to Fig. 12 is another motor vehicle constructed according to the present teachings, generally indicated by the reference numeral 10'. The vehicle 10' is generally similar to the vehicle 10 of Fig. 1, except that the primary driveline 16' and the secondary driveline 20' have been modified to incorporate a two-speed range unit in the output unit 18' and the rear drive module 100'. As will be explained below, this alternative drive system arrangement for the vehicle 10' enables at least one all-wheel drive low-range drive mode to be established in addition to the two-wheel drive high-range drive mode and all-wheel drive high-range drive mode associated with the vehicle 10. For ease of illustration, primed reference numerals are used to designate components that are generally similar in structure and / or function to the non-primed components previously described with respect to Fig. 1 to 11 were described.

[0056] With additional reference to Fig. 13, the output unit 18' is generally shown as including a housing 46', an input 48' adapted for connection to an output member of the transmission 26', an output 50', a transfer gear assembly 52', a first differential 30', an interrupt mechanism 54', a two-speed range unit 198, and an interrupt actuator 56'. The input 48' may include a sleeve input shaft 204 rotatably supported by the housing 46' and surrounding the axle shaft 34L'. The output 50' may include an output pinion shaft 60' including a drive pinion 62'. The transfer gear assembly 52' may include a sleeve transfer shaft 64', a helical gear set 66', and a hypoid gear 68' meshing with the drive pinion 62'. The helical gear set 66' may include a first helical gear 70' fixed for rotation with the distributor shaft 64' and a second helical gear 72' meshing with the first helical gear 70'.The second helical gear 72' and the hypoid gear 68' are formed integrally with or fixed to a stub shaft 74' which is rotatably mounted in the housing 46'.

[0057] The two-speed range unit 198 may include a planetary gear assembly 200 and a range shifting mechanism 202. The planetary gear assembly 200 may include a ring gear 206 non-rotatably fixed to the housing 46', a sun gear 208, a plurality of planet gears 210 meshing with both the ring gear 206 and the sun gear 208, and a planet carrier 212 rotatably supporting the planet gears 210. The planet carrier 212 is integrally formed with or fixed to the first differential case 38' of the first differential 30' for common rotation.

[0058] The range shift mechanism 202 may include a sun gear shaft 220 surrounding a portion of the first axle shaft 34L' and fixed for rotation with the sun gear 208, a carrier shaft 222 surrounding a portion of the sun gear shaft 220 and fixed for rotation with the planetary carrier 212, and a tubular range sleeve 224 surrounding portions of the carrier shaft 222, the sun gear shaft 220, and the input shaft 204. The input shaft 204 may have a first end 226 adapted for connection to the output of the transmission 26' via a splined shaft 227 ( Fig. 14) and having a second end having a set of elongated external splines 228 formed thereon. The range sleeve 224 may include a set of internal splines 230 in continuous meshing engagement with the external splines 228 on the drive shaft 204. Thus, the range sleeve 224 is connected for common rotation with the drive shaft 204 while being capable of bidirectional axial sliding movement between a plurality of predetermined range positions thereon, which are detailed below. The range sleeve 224 further defines a set of internal clutch splines 232 that can be moved into and out of engagement with a set of external clutch splines 234 formed on the support shaft 222 or a set of external clutch splines 236 formed on the sun gear shaft 220.

[0059] The interrupt mechanism 54' is generally similar in function to the interrupt mechanism 54 in that it is configured to selectively connect the input shaft 204 to the transfer gear assembly 52' to transfer rotational power from the input shaft 204 to the output pinion shaft 60' when all-wheel drive is desired. However, the interrupt mechanism 54' differs in that the drive connection between the input shaft 204 and the transfer shaft 64' is made indirectly via the range sleeve 224. In particular, the range sleeve 224 may include first and second sets of outer splines 240 and 242, respectively, which are selectively engageable with inner splines 244 formed on a mode sleeve 246.Thus, the mode sleeve 246 may be connected for rotation to the range sleeve 224 and is capable of bidirectional axial translation relative to the range sleeve 224 between a first (2WD) operating position and a second (AWD) operating position.

[0060] In the first operating position, a set of inner clutch splines 248 formed on the mode sleeve 246 are disengaged from the outer clutch splines 78' on the distributor shaft 64', thereby preventing rotational power from being transmitted from the input shaft 204 through the transfer gear assembly 52' to the output pinion shaft 60'. In contrast, when the mode sleeve 246 is in its second operating position, its inner splines 244 are engaged with one of the first and second sets of outer splines 240 and 242 (depending on the axial position of the range sleeve 224), and its inner clutch splines 248 are engaged with the clutch splines 78' on the distributor shaft 64', thereby establishing a driving connection between the input shaft 204 and the output pinion shaft 60'.

[0061] The two-speed range unit 198 is operable to establish at least two different speed ratio drive connections between the input shaft 204 and the first differential 30'. In particular, the range sleeve 224 is axially displaceable between a plurality of predetermined range positions.

[0062] In a first or "high" (Hi) range position, the range sleeve 224 is arranged so that its inner clutch splines 232 are engaged with the outer clutch splines 234 on the carrier shaft 222. Because the inner splines 230 on the range sleeve 224 remain in constant meshing engagement with the outer splines 228 on the input shaft 204, the position of the range sleeve 224 in its high range position causes a direct drive connection to be established between the input shaft 204 and the carrier shaft 222, which in turn is connected to the first differential case 38' via the carrier 212. Thus, a first or direct ratio drive connection is established between the input shaft 204 and the first differential 30'.

[0063] In a second or "neutral" range position, the range sleeve 224 is decoupled from the drive connection to both the carrier shaft 222 and the sun gear shaft 220, so that the drive shaft 204 is decoupled from the first differential 30'.

[0064] In a third or "low" range position, the range sleeve 224 is arranged so that its inner clutch teeth 232 are engaged with the outer clutch teeth 236 formed on the sun gear shaft 220. With the range sleeve 224 in its low range position, a second drive connection, or reduced ratio connection, is established between the input shaft 204 and the first differential 30'. In particular, the driven rotation of the sun gear shaft 220 causes the planetary gear assembly 200 to drive the carrier 212 at a reduced speed relative to the input shaft 204, so that the primary driveline 16' is equally driven at a reduced speed ratio through the first differential 30'.

[0065] Further with regard to Fig. 13, the interrupt actuator 56' is shown adjacent to the housing 46' and may include a first shift fork 84' engaged with the mode sleeve 246, a second shift fork 250 engaged with the range sleeve 224, and a power-driven unit 252 configured to receive control signals from the control unit 150 and operable to coordinate the movement of the shift forks 84' and 250. The power-driven unit 252 may be any type of unit capable of selectively translating the first shift fork 84' to cause movement of the mode sleeve 246 between its two operating positions and simultaneously selectively translating the second shift fork 250 to cause movement of the range sleeve 224 between its three range positions.

[0066] In relation to Fig. 14 and Fig. 15 shows a more definitive structural configuration of the components associated with the two-speed output unit 18'. In particular, Fig. 14 is an exploded perspective view of an exemplary embodiment of the two-speed output unit 18'. A housing 46' is shown as a multi-piece assembly including a main housing 258 upon which a differential case 260 and a PTU housing 262 are mounted. Fig. 15 is a cross-sectional view showing the compact arrangement of the planetary gear assembly 200, the range shift mechanism 202, the transfer gear assembly 52', and the movable mode sleeve 246 and the range sleeve 224.

[0067] As will be understood, the bidirectional translational movement of the range sleeve 224 and the mode sleeve 246 can be coordinated to enable a variety of mode and range combinations for the two-speed output unit 18' based on control signals from the control unit 150. With respect to Fig. 16a to 16d can illustrate these different mode and range combinations more clearly.

[0068] Fig. 16a shows the positions of the range sleeve 224 and the mode sleeve 246 for establishing a two-wheel high-range (2-Hi) mode. In particular, the mode sleeve 246 is shown in its first operating position, while the range sleeve 224 is in its first range position. Thus, the drive shaft 204 is connected to the carrier shaft 222 via the range sleeve 224 to establish the direct drive connection between the drive system 12 and the primary driveline 16'. Simultaneously, the transfer shaft 64' is decoupled from the drive connection to the drive shaft 204, thereby decoupled the secondary driveline 20' from the drive system 12. Rotational power is therefore transmitted only through the drive system 12 to the primary driveline 16' without any speed reduction.

[0069] Fig. Figure 16b shows the positions of range sleeve 224 and mode sleeve 246 for establishing a four-wheel high-range (4-Hi) mode. Specifically, the high-range connection is held in its first range position by range sleeve 224, while mode sleeve 246 is shown moved to its second operating position. Thus, mode sleeve 246 establishes a drive connection from input shaft 204 (via range sleeve 224) to transfer shaft 64' to also transmit rotational power from drive system 12 to secondary driveline 20 without reducing speed.

[0070] Fig. Figure 16c shows the positions of the range sleeve 224 and the mode sleeve 246 for establishing a neutral, non-driven mode. As can be seen, the mode sleeve 246 is held in its second operating position, while the range sleeve 224 has been axially moved to its second range position such that its inner splines 232 are disengaged from the external clutch splines 234 on the carrier shaft 232 and the outer clutch splines 236 on the sun gear shaft 220. Thus, the input shaft 204 is decoupled from both inputs to the primary driveline 16', so that no rotational power is transmitted from the drive system 12 to the primary driveline 16'.Additionally, such movement of the range sleeve 224 to its second range position causes the inner splines 224 on the mode sleeve 246 to be disengaged from the set of outer splines 240 on the range sleeve 224 while the mode sleeve 246 maintains its connection to the distributor shaft 64'.

[0071] Fig. Figure 16d shows the position of the mode sleeve 246 and the range sleeve 224 for establishing a four-wheel low-range (4-Low) mode. Specifically, the mode sleeve 246 is held in its second operating position while the range sleeve 224 is axially moved to its third range position. Thus, the low-range drive connection is established through the range sleeve 224 between the input shaft 204 and the sun gear shaft 220, while the AWD connection is established through the mode sleeve 246. It should be noted that the inner splines 244 of the mode sleeve 246 are engaged with the second set of outer splines 242 as the range sleeve 224 moves from its neutral range position to its low-range position.Although it is possible to provide the external keys 240 and 242 on the range sleeve 224 in a continuous arrangement, it has been found that the non-toothed interruption space therebetween prevents potential tooth locking conditions when moving the range sleeve 224 between its high range and low range positions.

[0072] Especially with regard to Fig. 12 and Fig. 17, the second driveline 16' may include the propeller shaft 86, a two-wheel rear drive module 10', a pair of second axle shafts 102L' and 102R', and the set of second vehicle wheels 104L and 104R. A first end of the propeller shaft 86 is connected to the output pinion shaft 60' extending from the two-speed output unit 18', while a second end of the propeller shaft 86 is connected for rotation with an input 106' of the two-speed rear drive module 100'. The rear drive module 100' may include a housing 108', a second differential 110', a torque-transmitting device 112' generally configured and arranged to selectively couple and transmit rotational power from the input 106' to the second differential 110', a TTD actuator 114' for controlling actuation of the torque-transmitting device 112', a two-speed range unit 278 having a planetary gear arrangement 280 and a range shift mechanism 282, and a range actuator 284.

[0073] The input 106' may include a drive pinion shaft 116' with a drive pinion 118', a hollow roller 120', and a hypoid gear 122' fixed to the roller 120' and meshing with the drive pinion 118'. The second differential 110' includes a second differential case 124', at least a pair of second drive pinions 126' rotatably supported by the second differential case 124', and a pair of second output side gears 128' meshing with the second drive pinions 126'. The second output side gears 128' are connected for rotation with the inboard ends of the second axle shafts 102L', 102R'.

[0074] The torque-transmitting device 112' is generally similar to the torque-transmitting device 112 and may include an input clutch member 130', a driven clutch member 132', a clutch pack 134', and an engagement member 136' movable under the control of the TTD actuator 114' based on control signals from the controller 150. The driven clutch member 132' may be a clutch drum 162' connected for rotation to a clutch output shaft 286. As a result, torque is transferred from the input 106' to the clutch output shaft 286 via the torque-transmitting device 112'.

[0075] The two-speed range unit 278 is operable to establish at least two different speed ratio drive connections between the output clutch member 132' and the second differential 110'. Specifically, the planetary gear assembly 280 may include a sun gear 290 fixed for rotation with the clutch output shaft 286, a ring gear 292 non-rotatably fixed to the housing 108', a plurality of planet gears 294 meshing with the sun gear 290 and the ring gear 292, and a planet carrier 296 from which the planet gears 294 are rotatably supported.The range shift mechanism 282 may include a first or direct clutch ring 300 fixed for rotation with the clutch output shaft 286, a second or low clutch ring 302 fixed for rotation with the planetary carrier 296, a third or drive clutch ring 304 fixed for rotation with a differential input shaft 306, a fourth or lock-up clutch ring 308 fixed for rotation with the second axle shaft 102R', and a range sleeve 310. The differential input shaft 306 may surround the second axle shaft 102R' and is connected for rotation with the second differential case 124' of the second differential 110'.

[0076] The range sleeve 310 may include a set of internal splines 312 that are continuously meshed with a set of external splines 314 formed on the input clutch ring 304. Thus, the range sleeve 310 is connected for common rotation with the input clutch ring 304 while being capable of bidirectional axial sliding movement thereon. The range sleeve 310 further includes a set of internal clutch teeth 316. As will be further explained, translational movement of the range sleeve 310 is feasible to establish the two different speed range drive connections between the output shaft 286 of the torque-transmitting device 112' and the second differential case 124' of the second differential 110'.

[0077] The range sleeve 310 is in Fig. 17a as being arranged in a first or high-range position such that its inner splines 312 mesh with the outer splines 314 on the input clutch ring 304 and with a group of outer splines 318 formed on the high clutch ring 300. As can also be seen, the clutch splines 316 on the range sleeve 310 are disengaged from meshing engagement by a group of outer clutch splines 320 formed on the low clutch ring 302. This establishes a first or direct ratio drive connection between the output clutch member 132' and the second differential case 124' of the second differential 110' via the clutch output shaft 286, the range sleeve 310, and the differential input shaft 306.

[0078] The range sleeve 310 is in Fig. 17b is arranged in a second or neutral position such that its inner gear teeth 312 remain engaged only with the outer gear teeth 314 on the input clutch ring 304, while its inner clutch teeth 316 remain decoupled from the outer clutch teeth 320 on the low clutch ring 302. Therefore, the output clutch element 132' is disengaged from the drive connection with the second differential case 124' of the second differential.

[0079] The range sleeve 310 is in Fig. 17c in a third or low-range position such that its inner splines 312 remain meshed with the outer splines 314 on the input clutch ring 304, while its inner clutch splines 316 now mesh with the outer clutch teeth 318 on the low clutch ring 302. Thus, the input rotation of the sun gear 290 (via the clutch output shaft 286) causes the planet carrier 296 to rotate at a reduced speed to establish a second or reduced ratio drive connection between the output clutch member 132' and the differential case 124' via the carrier 296, the low clutch ring 302, the range sleeve 310, the input clutch ring 304, and the second differential input shaft 306.

[0080] Fig. Finally, Figure 17d shows the range sleeve 310 in a fourth or low-lock position. In this position, the inner splines 312 on the range sleeve 310 mesh with the outer splines 314 on the drive clutch ring 304 and a group of outer splines 322 formed on the lock clutch ring 308, while the inner clutch teeth 316 on the range sleeve 310 remain engaged with the outer clutch teeth 320 on the low clutch ring 302. In this position, the drive connection remains at a reduced ratio of Fig. 17c, wherein in addition the second differential 110' is now locked, since the second differential housing 124' and the second axle shaft 102R are prevented from rotating relative to each other.

[0081] Further with regard to Fig. 17a through 17d, the range actuator 284 may comprise any type of power-driven mechanism operable to control the axial translational movement of a range fork 324, which in turn causes movement of the range sleeve 310 between its four different range positions. The range actuator 284 is shown mounted on the housing 108' of the two-speed rear drive module 100'. The range actuator 284 is preferably a motor-driven transmission device configured to receive control signals from the control unit 150 to convert the rotation of the engine output into translational movement of the range fork 324.

[0082] As mentioned, Fig. 17a to 17d schematically show the components that can be assigned to the two-speed rear-wheel drive module 100'. With reference to Fig. 18 through 22, a more definitive structural configuration of such components associated with an exemplary embodiment of the two-speed rear drive module 100 will now be provided. In particular, a splined connection 330 is provided to connect the clutch drum 162' to a first end of the clutch output shaft 286. It is also shown that the sun gear 290 may be integrally formed with the clutch output shaft 286.

[0083] In relation to Fig. 23 is a partial cross-sectional view of an alternative exemplary embodiment of the two-speed rear drive module 100' including a modified range shift mechanism 282'. Essentially, the range shift mechanism 282' is similar to that shown in Fig. 17 to 22, except that the low-lock clutch ring 308 has been removed to thereby accommodate the range shift mechanism 282 shown in Fig. 17d. Therefore, the range sleeve 310 may be slightly modified in design, but is still operable to establish the high-range, neutral, and low-range drive connections between the clutch output shaft 286 and the differential input shaft 306.

[0084] In operation, the vehicle 10' may normally be operated in a two-wheel high-range drive mode in which the output unit 18' establishes a high-range drive connection between the drive system 12 and the primary driveline 16' while the rear drive module 100 is disengaged. In particular, the range sleeve 224 and the mode sleeve 246, respectively associated with the range shift mechanism 202 and the interrupt mechanism 54', are as shown in Fig. 16a to establish the 2-Hi mode. When the mode sleeve 246 is in its first operating position, the drive shaft 204 is decoupled from the transfer shaft 64', so that substantially all of the rotational power from the drive system 12 is transferred to the primary driveline 16'. The torque-transmitting device 112' remains in its first (interrupted) mode to disconnect the secondary driveline 20'. While the torque-transmitting device 112' is operating in its interrupted mode, the range sleeve 310 may be in its high-range position ( Fig. 17a).

[0085] When it is desired or required to operate the motor vehicle 10' in an all-wheel-drive high-range (AWD-H) drive mode, the control system 22 may be activated to initially signal the TTD actuator 114' to shift the torque-transmitting device 112' to its second (connected) mode to synchronize the speed of the primary driveline 16' and the secondary driveline 20'. Upon synchronization, the control unit 150 signals the actuator 56' to shift the mode sleeve 246 to its second operating position while maintaining the range sleeve in its first range position ( Fig. 16b). This establishes a four-wheel high-range drive connection between the drive system 12, the primary driveline 16', and the input 106' to the rear drive module 100'. Furthermore, the range actuator 284 can be activated to maintain or move the range sleeve 310 in its high-range position ( Fig. 17a), such that rotational power supplied via the torque-transmitting device 112' is transmitted to the second differential 110' at a direct speed ratio. Subsequently, the TTD actuator 114' can be controlled to vary the torque transmitted via the torque-transmitting device 112' to the second vehicle wheels 104L, 104R, with the second differential 110' operating in an open state to permit a speed difference between the second wheels 103L, 104R.

[0086] During operation of the vehicle 10' in its AWD-H drive mode, if it is desired or determined that improved traction requires operation in the all-wheel drive low-range (AWD-L) drive mode, the control system 22 operates to coordinate switching of the output unit 18' to its four-wheel drive low-range mode and the rear-wheel drive module 100' to its low-range mode. In particular, the positions of the mode sleeve 246 and the range sleeve 224 of the output unit 18' to establish this connection are Fig. 16d, while the position of the area sleeve 310 of the rear drive module 100' for establishing this connection in Fig. 17c. Thus, the low-range drive connections are established in the output unit 18' and the rear drive module 100'. These low-range drive connections may be established sequentially or simultaneously, based on a suitable control method, when the vehicle 10' is in a stationary or non-moving state.

[0087] If, during operation of the vehicle 10' in its AWD-L drive mode, it is desired or determined that locking the second differential 110' would help provide even greater traction, the control system 22 may request operation of the vehicle in an all-wheel drive low-lock range (AWD-LOCK) drive mode. This results in the range actuator 284 being signaled to move the range sleeve 310 to its low-lock position ( Fig. 17d) while the output unit 18' is in its four-wheel low-range mode ( Fig. 16d).

[0088] Finally, a towing mode for the vehicle 10' can be established by setting the output unit 18' to its neutral mode ( Fig. 16c) and the rear drive module is pushed 100' into its neutral mode ( Fig. 17b).

[0089] Although specific aspects have been described in the specification and illustrated in the drawings, those skilled in the art will understand that various changes may be made and equivalents may be substituted for elements and components thereof without departing from the scope of the present teachings as claimed. Furthermore, mixing and matching of features, elements, components, and / or functions between various aspects of the present teachings are expressly contemplated herein, so those skilled in the art will recognize from the present teachings that, where appropriate, features, elements, components, and / or functions of one aspect of the present teachings may be incorporated into another aspect, unless otherwise described above.Furthermore, many changes may be made to adapt a particular situation, configuration, or material to the present teachings without departing from the essential scope thereof. Therefore, it is intended that the present teachings not be limited to the particular aspects illustrated by the drawings and described in the specification as the presently best mode contemplated for practicing the present teachings, but that the scope of the present teachings includes many aspects and examples that follow within the scope of the above description and the appended claims.

Claims

[1] A vehicle powertrain comprising: a drive shaft (204) rotatable about a first axis; a range sleeve (224) concentric with the drive shaft, the range sleeve being non-rotatably but slidably coupled to the drive shaft and movable along the first axis between a first range sleeve position and a second range sleeve position; a mode sleeve (246) concentric with the drive shaft, the mode sleeve being slidable along the first axis between a first mode sleeve position and a second mode sleeve position; a planetary gear assembly (200) having a planet carrier (212), a sun gear (208) and a plurality of planet gears (210) rotatably mounted on the planet carrier and meshing with the sun gear; a differential unit (30') having a differential housing (38') and a differential gear set, the differential housing being coupled to the planetary carrier (212) for common rotation about the first axis, the differential gear set being disposed in the differential housing and including a pair of differential output elements (42'); an axle shaft (34L') coupled for rotation to one of the differential output members (42'), the axle shaft extending through the sun gear (208) and the drive shaft; and a transmission gear assembly (52') having an input (64') and an output (60'), the output being rotatable about a second axis; wherein placement of the range sleeve (224) in the first range sleeve position couples the planet carrier (212) to the input shaft (204) for common rotation, and wherein placement of the range sleeve in the second range sleeve position couples the sun gear (208) to the input shaft for common rotation; wherein the disposition of the mode sleeve (246) in the first mode sleeve position when the range sleeve (224) is in the first range sleeve position decouples the range sleeve from the input (64') to allow relative rotation between the range sleeve and the input, and wherein the disposition of the mode sleeve in the second mode sleeve position when the range sleeve is in the first range sleeve position couples the range sleeve to the input for common rotation. [2] The vehicle drivetrain of claim 1, wherein the input (64') is rotatable about the first axis. [3] The vehicle driveline of claim 1, wherein the output (60') includes a first gear (62') meshing with a second gear (68'). [4] A vehicle driveline according to claim 3, wherein the second gear (68') is rotatable about a third axis offset from, but parallel to, the first axis. [5] The vehicle driveline of claim 1, wherein the input (64') includes a first intermediate gear (70), and wherein the first intermediate gear meshes with a second intermediate gear (72) mounted on an intermediate shaft (74). [6] The vehicle driveline of claim 1, wherein the range sleeve (224) includes a first set of mode sleeve teeth and a second set of mode sleeve teeth spaced apart from the first mode sleeve teeth, the first set of mode sleeve teeth engaging the mode sleeve (246) when the mode sleeve is in the second mode sleeve position and the range sleeve is in the first mode sleeve position, and the second set of mode sleeve teeth engaging the mode sleeve when the mode sleeve is in the second mode sleeve position and the range sleeve is in the second range sleeve position. [7] The vehicle drivetrain of claim 1, comprising a rear drive module (100') driven by the output (60'). [8] The vehicle powertrain of claim 7, wherein the rear drive module (100') includes a two-speed transmission (278) driven by the output (60') and a differential mechanism (110') driven by the output of the two-speed transmission. [9] The vehicle driveline of claim 8, wherein the rear drive module (100') further comprises a drive pinion (118') coupled to the output (60') via a longitudinal shaft (86) and a clutch (112') selectively interrupting power transmission between a pair of rear axle shafts (102L', 102R') and the drive pinion. [10] A vehicle powertrain comprising: a drive shaft (204) rotatable about a first axis; a range sleeve (224) concentric with the drive shaft, the range sleeve being non-rotatably but axially slidably coupled to the drive shaft; a mode sleeve (246) arranged concentrically to the drive shaft; a differential unit (30') having a differential housing (38') and a differential gear set, the differential housing being rotatable about the first axis, a two-speed transmission (198) configured to receive rotational power from the range sleeve (224), the two-speed transmission delivering rotational power to the differential housing (38'); and a transmission gear assembly (52') having an input (64') and an output (60'), the output being arranged along a second axis; wherein the two-speed transmission (198) operates in a first gear ratio when the range sleeve (224) is positioned in a first range sleeve position, wherein the two-speed transmission operates in a second gear ratio when the range sleeve is positioned in a second range sleeve position; wherein the mode sleeve (246) is movable between a first mode sleeve position in which the mode sleeve is disengaged from the input (64') and the range sleeve (224), and a second mode sleeve position in which the mode sleeve is in a position capable of transmitting rotational force between the range sleeve and the input; and wherein movement of the range sleeve (224) and the mode sleeve (246) is coordinated to provide a high-range two-wheel drive operating mode, a high-range four-wheel drive operating mode, and a low-range four-wheel drive operating mode. [11] The vehicle drivetrain of claim 10, wherein the input (64') is rotatable about the first axis. [12] The vehicle driveline of claim 10, wherein the output (60') includes a first gear (62') meshing with a second gear (68'). [13] A vehicle driveline according to claim 12, wherein the second gear (68') is rotatable about a third axis offset from, but parallel to, the first axis. [14] The vehicle driveline of claim 10, wherein the input (64') includes a first intermediate gear (70) and the first intermediate gear meshes with a second intermediate gear (72) mounted on an intermediate shaft (74). [15] The vehicle driveline of claim 10, wherein the two-speed transmission (198) is a planetary gear arrangement. [16] The vehicle driveline of claim 10, wherein the range sleeve (224) supplies rotational power to a first member (222) of the two-speed transmission (198) when the range sleeve is in the first range sleeve position, and wherein the range sleeve supplies rotational power to a second member (220) of the two-speed transmission (198) when the range sleeve is in the second range sleeve position. [17] The vehicle driveline of claim 10, wherein the range sleeve (224) includes a first set of mode sleeve teeth and a second set of mode sleeve teeth spaced apart from the first mode sleeve teeth, the first set of mode sleeve teeth engaging the mode sleeve (246) when the mode sleeve is in the second mode sleeve position and the range sleeve is in the first mode sleeve position, and the second set of mode sleeve teeth engaging the mode sleeve when the mode sleeve is in the second mode sleeve position and the range sleeve is in the second range sleeve position. [18] The vehicle powertrain of claim 10, further comprising a rear drive module (100') driven by the output (60'). [19] The vehicle powertrain of claim 18, wherein the rear drive module includes a two-speed transmission (278) driven by the output (60') and a differential mechanism (110') driven by an output (60') of the two-speed transmission. [20] The vehicle driveline of claim 19, wherein the rear drive module further comprises a drive pinion (118') coupled to the output (60') via a longitudinal shaft (86) and a clutch (112') selectively interrupting power transmission between a pair of rear axle shafts (102L', 102R') and the drive pinion. [21] A rear-wheel drive module (100') for a drive train of an all-wheel drive motor vehicle, the rear-wheel drive module comprising: an axle housing (108'); a drive pinion (118') rotatably connected to the axle housing (108'); a sleeve (120') rotatably coupled to the axle housing (108'); a ring gear (122') rotatably connected to the sleeve (120'), the ring gear engaging the drive pinion (108'); a disconnect clutch having a first clutch member (130") and a second clutch member (132'), the first clutch member coupled to the sleeve (120') for rotation therewith, the disconnect clutch configured to selectively transmit rotational power between the first and second clutch members; a two-speed transmission (278') having a transmission input element (290) which is non-rotatably connected to the second clutch element (132') and a transmission output element; a hollow shaft (306) configured to be driven by the transmission output member; a differential unit (110') having a differential housing (124) and a differential gear set with a pair of differential outputs (128'), the differential housing being coupled to the hollow shaft (306) for rotation therewith, the differential gear set being configured to receive rotational power from the differential housing and to output rotational power to the differential outputs; and a pair of axle shafts (102L', 102R'), each axle shaft (102L', 102R') being non-rotatably connected to one of the corresponding differential outputs (128'). [22] The rear-wheel drive module of claim 21, wherein the disconnect clutch is a friction clutch having a clutch pack (134') configured to transmit rotational power between the first and second clutch members (130", 132'). [23] Rear-wheel drive module according to claim 21, wherein a portion of the first coupling element (130") is arranged radially between the sleeve (120') and the hollow shaft (306). [24] Rear-wheel drive module according to claim 21, wherein the differential unit (110') and the disconnect clutch are located on opposite sides of the sleeve (120'). [25] Rear-wheel drive module according to claim 21, wherein a part of the differential housing (124) is arranged radially between the sleeve (120') and the hollow shaft (306). [26] Rear-wheel drive module according to claim 21, wherein the ring gear (122') is closer to the separating clutch than to the differential unit (110'). [27] The rear-wheel drive module of claim 21, wherein the transmission output member is movable along a rotational axis of the transmission output member. [28] The rear-wheel drive module of claim 27, wherein the transmission output member is movable along the rotational axis to a position in which it is coupled for rotation to one of the axle shafts (102L', 102R'). [29] Rear-wheel drive module according to claim 21, wherein the two-speed transmission (278') has a planetary gear stage. [30] The rear-wheel drive module of claim 29, wherein the planetary gear stage comprises a sun gear (290) and a planet carrier (296), and wherein the transmission output member is rotationally coupled to the sun gear (290) when the two-speed transmission (278') is operating in a first gear ratio, and wherein the transmission output member is rotationally coupled to the planet carrier (296) when the two-speed transmission (278') is operating in a second gear ratio. [31] Rear-wheel drive module according to claim 21, wherein the hollow shaft (306) is received in the sleeve (120'). [32] Rear-wheel drive module (100') for the drive train of a motor vehicle with all-wheel drive, the rear-wheel drive module (100') comprising: an axle housing (108'); a drive pinion (118') rotatably connected to the axle housing (108'); a sleeve (120') rotatably coupled to the axle housing (108'); a ring gear (122') rotatably connected to the sleeve (120'), the ring gear (122') engaging the drive pinion (118'); a disconnect clutch having a first clutch element (130") and a second clutch element (132'), the first clutch element (130") coupled to the sleeve (120') for rotation therewith, the disconnect clutch being configured to selectively transmit rotational power between the first and second clutch elements (130", 132'); a differential unit (110') having a differential housing (124) and a differential gear set with a pair of differential outputs (128'), the differential gear set being configured to receive rotational power from the differential housing (124) and deliver rotational power to the differential outputs (128'), a hollow shaft (306) received in the sleeve (120') and coupled to the differential housing (124) for rotation therewith, the hollow shaft (306) configured to transmit rotational power in a power path between the disconnect clutch and the differential unit (110'); a pair of axle shafts (102L', 102R'), each axle shaft being rotationally connected to a corresponding differential output (128'); and a sleeve (310) movable between a first position and a second position along a rotational axis of the hollow shaft (306), the sleeve (120') being coupled to the hollow shaft for rotation therewith, and wherein the arrangement of the sleeve (120') in the second position prevents relative rotation between the hollow shaft (306) and one of the axle shafts (102L', 102R').

Images