CLUTCH ARRANGEMENT

Abstract

Coupling arrangement comprising: a first rotary member; a second rotary member; a clutch sleeve (94, 172) coupled for rotation to the first rotary member and axially movable between a first position and a second position, the clutch sleeve (94, 172) having first clutch teeth (96, 182) disengaged from second clutch teeth (98, 184) formed on the second rotary member when in its first position, and the first clutch teeth (96, 182) on the clutch sleeve (94, 172) engaging the second clutch teeth (98, 184) when in its second position; a power-operated clutch actuator (74, 139) having an output member movable between a first position and a second position; and a switch isolation mechanism (304) operatively connecting the output member to the clutch sleeve (94, 172) such that movement of the output member between its first and second positions causes corresponding movement of the clutch sleeve (94, 172) between its first and second positions, wherein the switch isolation mechanism (304) includes a biasing arrangement configured to permit movement of the output member from its first position to its second position while a locked tooth condition between the first and second clutch teeth (96, 182 / 98, 184) prohibits movement of the clutch sleeve (94, 172) from its first position to its second position, and wherein the biasing arrangement is subsequently released and forcibly moves the clutch sleeve (94, 172) from its first position to its second position when the locked tooth condition is removed,and wherein the biasing arrangement of the switch isolation mechanism (304) permits movement of the output member to its second position while the clutch arrangement is in the locked tooth state, , characterized by that the switch isolation mechanism (304) includes a lower pivot lever (322, 322'), wherein the lower pivot lever (322, 322') has a spring retainer segment (340), a pivot segment (342, 342') and a fork segment (344), wherein the fork segment (344) is coupled to the coupling sleeve (94, 172), and wherein the pivot segment (342, 342') and the fork segment (344) are in a pivotal relationship about a pivot pin (350, 350'), and that the shift isolation mechanism (304) further includes an upper pivot lever (320, 320'), the upper pivot lever (320, 320') being configured to include a drive segment (326, 326') that engages the output member of the power-operated clutch actuator (74, 139), and a pivot segment (328, 328'), and, that the pivot segment (342, 342') of the lower pivot lever (322, 322') is pivotally connected to the pivot segment (328, 328') of the upper pivot lever (320, 320'), and that the biasing arrangement of the switch isolation mechanism (304) includes a spring arrangement (324, 324') having a spring bolt (370) extending between the upper pivot lever (320, 320') and the lower pivot lever (322, 322') and a spring (374, 374') surrounding the spring bolt (370), and that pivoting movement between the upper pivot lever (320, 320') and the lower pivot lever (322, 322') loads the spring (374, 374') into a locked tooth condition and unloads the spring (374, 374') after the locked tooth condition is removed, thereby forcibly pivoting the lower pivot lever (322, 322') to move the coupling sleeve (94, 172).

Description

AREA

[0001] The present disclosure generally relates to power-operated shift systems in powertrain assemblies used for automotive driveline applications. More particularly, the present disclosure relates to a power-operated clutch actuator for moving a clutch sleeve between a disengaged and an engaged position and including an electromagnetic actuator and a pivotable shift isolation mechanism for coupling the electromagnetic actuator to the clutch sleeve. BACKGROUND

[0002] The demand for four-wheel drive (4WD) and all-wheel drive (AWD) vehicles has led to the development of powertrain systems configured to selectively and / or automatically transfer torque from the driveline to all four wheels of the vehicle. In many four-wheel drive vehicles, the powertrain system includes a transfer case configured to driveably connect the driveline to a front and rear drivetrain.In particular, a majority of current transfer cases are configured to include a mainshaft or rear output shaft connecting the driveline to the rear driveline, a front output shaft connected to the front driveline, a transfer assembly drivingly connected to the front output shaft, a mode clutch for selectively coupling the transfer assembly to the rear output shaft, and a clutch actuator for controlling actuation of the mode clutch. The mode clutch is operable in a first or "disengaged" state to disconnect the front output shaft from the rear output shaft and establish a two-wheel drive (2WD) mode, with all drive torque from the driveline transferred to the rear driveline.The mode clutch is further operable in a second or "engaged" state to driveably connect the front output shaft (via the transfer assembly) to the rear output shaft and establish a four-wheel drive (4WD) mode wherein drive torque is transferred from the driveline to both the front and rear drivelines.

[0003] In many all-wheel drive vehicles, the powertrain system includes a power take-off unit (PTU) configured to connect the driveline to the rear driveline in conjunction with a front-wheel drive driveline arrangement. Typically, the mode clutch, in its disengaged state, is operable to disconnect the rear driveline (i.e., the rear propshaft and the rear axle) from the driveline. In its engaged state, however, the mode clutch is operable to connect the front axle differential (i.e., the transaxle output) to a hypoid gear set drivingly connected to the rear propshaft.

[0004] In both 4WD and AWD vehicles, it is further known to equip the secondary driveline (i.e., the front axle in 4WD systems and the rear axle in AWD systems) with a disconnect clutch to provide a "disconnect" function when the mode clutch is operated in its disengaged state. Thus, the use of mode clutches and disconnect clutches in power transmission systems is well known. Such clutches are typically configured as positive couplings with an axially movable clutch sleeve operatively disposed between a pair of rotating components. Movement of the clutch sleeve to a first position permits relative rotation between two rotating components and establishes the disengaged condition. Similarly, movement of the clutch sleeve to a second position prevents relative rotation between the two rotating components and establishes the engaged condition.In many cases, a power-operated clutch actuator is employed to move the clutch sleeve between its two different operating positions. However, the power-operated clutch actuator must be operable to accommodate "locked" shifts in the engaged state and function to perform the mode shift once the locked condition is removed. To meet this locked shift requirement, some arrangements employ a spring-loaded mechanism between the power-operated clutch actuator and the clutch sleeve to limit the power output requirements and improve the operating life of the power-operated clutch actuator.

[0005] US 2015 / 0 059 508 A1 discloses a transfer case with a shift mechanism for a clutch assembly. The transfer case has an input shaft arranged coaxially with a range input shaft. The input shaft can be selectively coupled to the range input shaft via the clutch assembly for transmitting torque. For this purpose, the clutch assembly comprises the shift mechanism with a clutch sleeve, wherein the clutch sleeve is operable into a neutral position and into engaged positions. In the switchable engaged positions, torque can be transferred from the range input shaft to the input shaft. The shift mechanism includes a spring-loaded biasing assembly.

[0006] Document US 4 770 280 A shows a spring-assisted transfer case fork assembly for switching a synchronizer clutch sleeve from its neutral position to an engaged position to complete a full engagement of its internal gearing with external gearing on a transmission shaft speed change gear.

[0007] DE 25 21 139 A1 discloses a spring-loaded shifting device for actuating a shift fork of a transmission's dog clutch. This shifting device comprises a two-armed, spring-loaded toggle joint, one arm of which carries the preloadable spring and the other arm of which is connected at its free end to the shift shaft. After a manually initiated shift position change, the clutch parts to be shifted are loaded with spring force in the actuation direction until they automatically engage.

[0008] From EP 0695 892 A2 a shift mechanism for a gear change transmission is known in which the shift forks are initially moved and / or preloaded by a plurality of springs which are displaced by a linear actuator.

[0009] The document DE 11 2015 000 903 T5 relates to an actuator that can be used to move a switchable element in a powertrain component.

[0010] The object of the present invention is, based on known clutch arrangements, to develop an alternative power-operated switching system which represents an improvement over otherwise conventional power-operated switching systems.

[0011] This object is achieved by a coupling arrangement having the features of claim 1. SUMMARY

[0012] One aspect of the present disclosure is to provide a clutch assembly including a shift isolation mechanism for biasing a clutch sleeve to an engaged position from a disengaged position when the clutch assembly is in a locked tooth condition that prohibits movement of the clutch sleeve. Upon removal of the locked tooth condition, the shift isolation mechanism positively moves the clutch sleeve to the engaged position, thereby permitting unified rotation of two rotary members by mating the clutch sleeve.

[0013] Another aspect of the present disclosure is to provide a power-operated clutch actuator having an output member movable between an extended position and a retracted position in accordance with movement of the clutch sleeve.

[0014] Another aspect of the present disclosure is the integration of the clutch assembly into a power-operated shifting system of an automobile.

[0015] According to these and other aspects, the present disclosure provides a clutch assembly including a first rotating member and a second rotating member of an automobile. A clutch sleeve is rotationally coupled to the first rotating member and is axially movable between a first position and a second position. In the first position, the clutch sleeve has first clutch teeth disengaged from second clutch teeth formed on the second rotating member. In the second position, the first clutch teeth on the clutch sleeve engage the second clutch teeth. A power-operated clutch actuator has an output member movable between a first position and a second position.A shift isolation mechanism operatively connects the output member to the clutch sleeve such that movement of the output member between its first and second positions causes corresponding movement of the clutch sleeve between its first and second positions. The shift isolation mechanism includes a biasing assembly configured to permit movement of the output member from its first position to its second position while a locked tooth condition between the first and second clutch teeth prohibits movement of the clutch sleeve from its first position to its second position. Upon removal of the locked tooth condition, the spring-loaded assembly is released to positively move the clutch sleeve from its first position to its second position.

[0016] Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are for purposes of illustration only and are not intended to limit the scope of the present disclosure. DRAWINGS Fig. 1 is a schematic illustration of a four-wheel drive motor vehicle configured to be equipped with a powertrain assembly and / or torque-transmitting couplings constructed in accordance with the teachings of the present disclosure; Fig. 2 is a schematic view of a Fig. 1 equipped with a power-operated mode clutch assembly according to the present disclosure; Fig. 3 is a schematic view of a disconnect torque transmitting coupling equipped with a power-operated disconnect clutch assembly according to the present disclosure; Fig. 4 is a schematic view of a four-wheel drive vehicle configured to be equipped with a powertrain assembly and at least one torque-transmitting coupling according to the present disclosure; Fig. 5 is a sectional view of a Fig. 4, equipped with a power-operated mode clutch assembly according to the present disclosure; Fig. 6 is a sectional view of a Fig. 4, which is equipped with a power-operated disconnect clutch arrangement; Fig. 7 is an isometric view of a portion of the Fig. 4 and Fig. 6, now illustrating in more detail a driven clutch actuator and a shift isolation mechanism associated with the power-operated disconnect clutch assembly; Fig. 8 is similar to Fig. 7 and illustrates the alignment and positioning of the components when the axially movable coupling sleeve is in its disengaged position to establish a disconnected mode; Fig. 9 resembles Fig. 8, but now illustrates the alignment and positioning of the components when the driven clutch actuator is actuated, the shift isolation mechanism is in a loaded condition, and the clutch sleeve is held in its disengaged position due to a locked shift condition; Fig. 10 and Fig. 11 resemble Fig. 9, but now illustrate the switch isolation mechanism in an unloaded condition, with the clutch sleeve being moved to its engaged position when the locked switch condition is overcome; Fig. 12 illustrates the alignment and positioning of the components when the disconnection operation is completed; Fig. 13 is an isometric view of an alternative embodiment of the driven clutch actuator and shift isolation mechanism for use with the power-operated disconnect clutch assembly of the present disclosure; and Fig. 14 is a sectional view of the Fig. 13 shown arrangement.

[0017] Corresponding numbers are used throughout all views to identify corresponding components. DETAILED DESCRIPTION

[0018] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context expressly indicates otherwise. The terms "comprises," "including," "including," and "having" are intended to be inclusive and therefore indicate the presence of recited features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.The procedures, processes, and operations described herein should not be construed as requiring their performance in the particular order discussed or illustrated, unless specifically stated as the order or sequence of performance. It is further understood that additional or alternative steps may be employed.

[0019] When an element or layer is described as being "on," "engaging with," "connected to," or "coupled to" another element or layer, it may be directly on, engaged with, connected to, or coupled to the other element or layer, or there may be intervening elements or layers. Conversely, when an element is described as being "directly on," "directly engaging with," "directly connected to," or "directly coupled to" another element or layer, there may be no intervening elements or layers. Other wording used to describe the relationship between elements should be interpreted in a similar way (for example, "between" versus "directly between," "adjacent" versus "directly next to," etc.).As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items.

[0020] Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers, and / or sections, these elements, components, regions, layers, and / or sections should not be limited by these terms. These terms may only be used to distinguish one element, component, region, layer, or section from another region, layer, or section. Terms such as "first," "second," and other numerical terms used herein do not imply a sequence or order unless clearly indicated by the context.Thus, a first element, component, region, layer, or portion discussed below could be referred to as a second element, component, region, layer, or portion without departing from the teachings of the embodiments.

[0021] Spatial terms such as "inner," "outer," "beneath," "under," "lower," "above," "upper," and the like may be used herein for convenience of description to describe the relationship of one element or feature to one or more other elements or features, as illustrated in the figures. Spatial terms are intended to encompass various orientations of the device in use or operation in addition to the orientation shown in the figures. For example, if the device in the figures is turned over, elements described as being "below" or "below" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary term "below" can encompass both an above and below orientation.The device may also be oriented differently (rotated by 90 degrees or in other orientations), and the descriptive terms used herein relating to the space will be interpreted accordingly.

[0022] At the beginning on Fig. 1 of the drawings, an example of a four-wheel drive motor vehicle 10 is shown generally including a longitudinally extending (i.e., north / south configuration) driveline 12 operable to generate rotational power (i.e., drive torque) for transmission to a first or rear driveline 14 and a second or front driveline 16. The driveline 12 is shown to include an internal combustion engine 18, a multi-speed transmission 20, and a transfer case 22. In the particular arrangement shown, the rear driveline 14 is the primary driveline and is configured to include a pair of ground-engaging wheels 24 drivingly connected via respective rear axle shafts 26 to a rear differential assembly 28 associated with a rear axle assembly 30.The rear driveline 14 further includes a rear propeller shaft 32 arranged to connect a rotary input 34 of the rear differential assembly 28 to a rear output shaft 36 of the transfer case 22. A pair of rear connecting units 38 connect opposite ends of the rear propeller shaft 32 to the rotary input 34 of the rear differential assembly 28 and the rear output shaft 36 of the transfer case 22 and operate to transmit drive torque while permitting angular and / or translational movement therebetween.

[0023] The front drive train 16 is the secondary drive train and is in Fig. 1 of the drawings; it is configured to include a pair of ground-engaging wheels 44 drivingly connected via respective front axle shafts 46 to a front differential assembly 48 associated with a front axle assembly 50. The front driveline 16 further includes a front propshaft 52 arranged to connect a rotary input 54 of the front differential assembly 48 to a front output shaft 56 of the transfer case 22. A pair of front interconnecting units 58 connect opposite ends of the front propshaft 52 to the rotary input 54 of the front differential assembly 48 and the front output shaft 56 of the transfer case 22 and operate to transmit drive torque while permitting angular and / or translational movement therebetween.A disconnect coupling 60 is also associated with the front driveline 16 and is shown operatively disposed between a pair of shaft segments 46A, 46B of one of the front axle shafts 46. The disconnect coupling 60 is operable in a first or "connected" mode for driveably coupling the front wheels 44 to the remainder of the front driveline 16 and is further operable in a second or "disconnected" mode for decoupled the front wheels 44 from drive connection with the remainder of the front driveline 16.

[0024] According to the presentation in Fig. 1, the powertrain 12 is also operatively associated with a powertrain control system 62, the latter generally including a group of vehicle sensors 64 and a mode selector 66, both of which provide signals for communication with a vehicle controller 68. The vehicle controller 68 may include one or more individual controllers associated with the engine 18, the transmission 20, the transfer case 22, and the disconnect clutch 60, and configured to control the propulsion operation of the vehicle 10. The powertrain control system 62 is shown providing an electronically controlled powertrain system configured to allow a vehicle operator to select between a two-wheel drive (2WD) mode and a part-time or "locked" four-wheel drive (LOCK-4WD) mode.In this regard, the transfer case 22 is equipped with a mode clutch 70 and a transfer assembly 72 configured to transfer drive torque to the front driveline 16 when one of the four-wheel drive modes is selected. As discussed in more detail below, the mode clutch 70 operates to selectively transfer drive torque from the rear output shaft 36 to the front output shaft 56 via the transfer assembly 72.

[0025] As shown, the powertrain system further includes a power-operated clutch actuator 74 for controlling actuation of the mode clutch 70 and a power-operated disconnect actuator 76 for controlling actuation of the disconnect clutch 60. The controller 68 controls the coordinated actuation of the power-operated actuators 74, 76 in response to input signals from vehicle sensors 64 and mode signals from the mode selection mechanism 66. The vehicle sensors 64 are arranged and configured to detect certain dynamic and operating characteristics of the vehicle 10 and / or current weather or road conditions.

[0026] To establish 2WD mode, clutch actuator 74 is controlled to switch mode clutch 70 to a first or "disengaged" mode, while disconnect actuator 76 is controlled to switch disconnect clutch 60 to its disengaged mode. When mode clutch 70 is in its disengaged mode, no drive torque is transmitted through transfer assembly 72 to front output shaft 56, so all drive torque generated by driveline 12 is delivered to rear wheels 24 via rear driveline 14.

[0027] To establish the LOCK 4WD mode, the disconnect actuator 76 is controlled to switch the disconnect clutch 60 to its connected mode, and the clutch actuator 74 is controlled to switch the mode clutch 70 to a second, or "fully engaged," mode. When the mode clutch 70 is operated in its fully engaged mode, the rear output shaft 36 is essentially drive-coupled to the front output shaft 56 via the transfer assembly 72, so that drive torque is evenly distributed (i.e., 50 / 50) therebetween. When the disconnect clutch 60 is in its connected mode, the shaft segments 46A, 46B are drive-coupled, so that drive torque delivered to the front output shaft 56 is transmitted to the front wheels 44 via the front driveline 16.

[0028] On Fig. 2, the transfer case 22 is shown in schematic format including a transfer case housing 80, an input shaft 42, a rear output shaft 36, a front output shaft 56, a transfer assembly 72, a mode clutch 70, and a power-operated clutch actuator 74. The main shaft 40 is a combination of the input shaft 42 and the rear output shaft 36, which in this single-stage version of the transfer case 22 are integrated into a common shaft. The transfer assembly 72 includes a first sprocket 82 rotatably supported on the main shaft 40, a second sprocket 84 fixed to the front output shaft 56, and an endless drive chain 86 surrounding and meshing with first sprocket teeth 88 formed on the first sprocket 82 and second sprocket teeth 90 formed on the second sprocket 84.The mode clutch 70 is a positive-lock clutch having a clutch hub 92 non-rotatably connected to the main shaft 40 and an axially movable clutch sleeve 94 splined for rotation with and axial movement relative to the clutch hub 92. The mode sleeve 94 is movable on the clutch hub 92 between a first (i.e., disengaged) or 2WD position and a second (i.e., engaged) or LOCK-4WD position. In the 2WD position, outer clutch teeth 96 on the clutch sleeve 94 are disengaged from meshing engagement with inner clutch teeth 98 formed on the first sprocket 82. In the LOCK-4WD position, the clutch teeth 96 on the clutch sleeve 94 mesh with the clutch teeth 98 on the first sprocket 82, thereby coupling the front output shaft 56 for common rotation with the main shaft 40.The clutch actuator 74 is shown schematically and is operable to control movement of the clutch sleeve 94 between its two different mode positions in response to a mode signal provided by the mode selector 66 to the controller 68. As will be detailed below, the mode clutch actuator 74 is configured to include a driven clutch actuator and a spring-loaded isolation linkage mechanism configured to connect an output of the driven clutch actuator to the mode sleeve 94.

[0029] Now on Fig. 3, the disconnect coupling 60 is shown in schematic format as including a disconnect sleeve 100 splined to a first clutch hub 102 that is non-rotatably connected to the axle shaft portion 46B and axially movable thereon between a first (i.e., disengaged) or disconnect position and a second (i.e., engaged) or connect position. In the shown disconnected position, inner clutch teeth 104 on the disconnect sleeve 100 are disengaged from outer clutch teeth 106 formed on a second clutch hub 108 that is non-rotatably connected to the axle shaft portion 46A to establish a disconnected mode, wherein the front wheel 44 is decoupled from the remainder of the front axle assembly 50.In the connected position, the clutch teeth 104 on the disconnect sleeve 100 mesh with the clutch teeth 106 on the second clutch hub 108 to establish a connected mode with the front wheel 44 drivingly connected to the front axle assembly 50. The disconnect actuator 76 is shown schematically and is operable to control movement of the disconnect sleeve 100 between its two different positions in response to the mode signal. In operation, the disconnect sleeve 100 is positioned in its disconnect position when the transfer case 22 is operating in its 2WD mode and is positioned in its connect position when the transfer case 22 is operating in its LOCK 4WD mode.As detailed below, the disconnect actuator 76 is configured to include a driven clutch actuator and a spring-loaded isolation linkage mechanism configured to connect an output of the driven clutch actuator to the disconnect sleeve 100.

[0030] Generally, the present disclosure also relates to a coupling system and / or a disconnect system for use in a driveline of a motor vehicle. A power take-off unit may be equipped with a mode clutch for disconnecting the driveline from a portion of the driveline and for subsequent reconnection to the driveline. In addition, another disconnect clutch may be provided for disconnecting a portion of the driveline from the vehicle wheels. The hypoid transmission of the vehicle driveline may be disconnected from the driveline to reduce churning losses and other mechanical imperfections.

[0031] With particular reference to Fig. 4 of the drawings, a driveline 110 of a four-wheel drive vehicle is shown. The driveline 110 includes a front driveline 112 and a rear driveline 114, both of which may be driven by a power source, such as an engine 116, through a transmission 118, which may be either a manual or automatic transmission. In the particular embodiment shown, the driveline 110 is an all-wheel drive system that includes a powertrain assembly 120 for transferring drive torque from the engine 116 and the transmission 118 to the front driveline 112 and the rear driveline 114. The powertrain assembly 120 is shown as a power take-off unit (PTU).

[0032] The front driveline 112 is shown to include a pair of front wheels 124 individually driven by a first axle shaft 126 and a second axle shaft 128. The front driveline 112 further includes a reduction gear set 130 and a differential assembly 132. The PTU 120 includes a mode clutch 134, a right-angle drive assembly 136, and a driven clutch mode actuator 139.

[0033] The rear driveline 114 includes a propshaft 138 connected at a first end to the right-angle drive assembly 136 and at an opposite end to a rear axle assembly 140. The rear driveline 114 further includes a pair of rear wheels 142 individually driven by a first rear axle shaft 144 and a second rear axle shaft 146. The rear axle assembly 140 further includes a hypoid ring gear and pinion gear set 148 that drives a rear differential assembly 150.

[0034] First and second disconnect couplings 152 and 154 selectively driveably disconnect the first and second rear axle shafts 144, 146 from the ring and pinion gear sets 148 and the rear differential assembly 150. The first and second disconnect couplings 152, 154 may be configured as dog clutches. The first disconnect coupling 152 is shown to include an axially movable first disconnect sleeve. A first disconnect actuator 156 for controlling movement of the first disconnect sleeve between its connected and disconnected positions is schematically shown. Also schematically shown is a second disconnect actuator 158 for controlling movement of a second axially movable disconnect sleeve associated with the second disconnect coupling 154.As detailed below, the disconnect actuators 156, 158 are each configured to include a driven clutch actuator and a spring-loaded isolation linkage mechanism configured to connect an output of the respective driven clutch actuator to the disconnect clutch sleeve.

[0035] Fig. 5 illustrates a non-limiting embodiment of the PTU 120 for receiving a housing 160 supporting an input shaft 162. The input shaft 162 is drivingly coupled to the driver of the front differential 132. A drive gear 164 is coupled to a transfer shaft 166. The mode clutch 134 selectively couples the transfer shaft 166 to the input shaft 162 and includes an input hub 168 fixed to the input shaft 162, an output hub 170 fixed to the transfer shaft 166, and a mode clutch sleeve 172. The drive gear 164 meshes with a pinion gear 174 to define the hypoid gear set 136. The pinion gear 174 is integrally formed with a pinion shaft 176, which is supported in the housing 160 via a pair of laterally spaced bearings 178. A coupling 180 is provided to connect the pinion shaft 176 to the rear propshaft 138.The mode sleeve 172 is splined for rotation with and axial movement on the input hub 168 between an engaged position (shown) and a disengaged position. In its AWD, or engaged, position, its clutch teeth 182 mesh with clutch teeth 184 on the output hub 170, thereby transmitting drive torque from the input shaft 162 through the hypoid gear set 136 to the propshaft 138. In its 2WD, or disengaged, position, the clutch sleeve 172 is disengaged from the output hub 170. As will be detailed, the power-operated PTU clutch actuator 139 controls such movement of the clutch sleeve 172.

[0036] Fig. Figure 6 shows a portion of the rear axle assembly 140. A housing 190 rotatably supports a pinion shaft 192 or a ring and pinion gear set 148 via bearings 194, 196. A pinion gear 198 is integrally formed with the pinion shaft 192. The ring and pinion gear set 148 further includes a ring gear 200 in meshing engagement with the pinion gear 198 and non-rotatably connected to a carrier 202. The carrier 202 is rotatably supported within the housing 190 by bearings 204. The differential assembly 150 includes a pair of pinion gears 206 supported on a crosspin 208 fixed to the carrier 202. A pair of side gears 210 mesh with the pinion gears 206. The side gears 210 are non-rotatably connected to flange shafts 212. Bearings 214 support the flange shafts 212 rotatably in the housing 190.

[0037] The disconnect coupling 152 is substantially similar to the disconnect coupling 154. Each disconnect coupling includes a drive flange 216 that is non-rotatably connected to its associated flanged shaft 212. A plurality of circumferentially spaced outer teeth 218 are formed on the drive flange 216. A driven spindle 220 is rotatably supported at a distal end of the flanged shaft 212. A plurality of circumferentially spaced outer teeth 222 are formed on the driven spindle 220. A disconnect sleeve 224 includes a plurality of inner teeth 226. The disconnect sleeve 224 is axially movable between a connected and a disconnected position. In the disconnected position, the teeth 226 of the disconnect sleeve 224 engage only the teeth 222 of the spindle 220. In the connected position, the teeth 226 simultaneously engage both the teeth 222 of the spindle 220 and the teeth 218 formed on the drive flange 216. The spindles 220 are connected to the first and second output flanges 230, 232, respectively.second rear axle shaft 144, 146. A shift fork 234 engages a groove 286 formed in the separator sleeve 224. A power-operated separator actuator (to be disclosed) translates the shift fork 234 axially to position the separator sleeve 224 in the connected position or the disconnected position. In the connected position, torque is transmitted through the separator sleeve 224 between the drive flange 216 and the spindle 220. In the disconnected position, the separator sleeve 224 does not drive-engage the drive flange 216, and no torque is transmitted between the flange shaft 212 from the spindle 220.

[0038] During vehicle operation, it may be beneficial to reduce churning losses associated with the drive ring gear and pinion gear set 148 and the right-angle drive assembly 136. The controller 68 communicates with various vehicle sensors 64 that provide data indicative of parameters such as vehicle speed, four-wheel drive mode, wheel slip, vehicle acceleration, and the like. At the appropriate time, the controller 68 provides a signal to the PTU actuator 139 to place the mode clutch 134 in the deactivated mode, in which no torque is transferred from the engine 116 to the rear driveline 114.Further, the controller 68 signals the isolation actuators connected to the isolation clutch 152 and the isolation clutch 154 to place the shift forks 234 in their disconnected positions so that energy associated with rotating the rear wheels 142 is not transferred to the ring and pinion gear set 148 or the differential assembly 150. Accordingly, the hypoid gear sets do not rotate at the rotational output speed of the differential assembly 132, nor do they rotate at the speed of the rear wheels 142. The hypoid gear sets are disconnected from all power sources and are not driven at all.

[0039] Now on the Fig. 7 to 12, a non-limiting embodiment of a power-operated shift system 300 for axially moving a clutch or a disconnect sleeve between a first and a second position to effect an engaged and disengaged position is disclosed. In this particular example, the power-operated shift system 300 is configured to axially move the disconnect sleeve 224 between its connected and disconnected positions to accordingly couple and uncouple the stub shaft 212 with respect to the driven spindle 220. The shift system 300 is shown in conjunction with the second disconnect coupling 154, but those skilled in the art will appreciate that the following detailed description clearly demonstrates its applicability to the first disconnect coupling 152, the PTU mode clutch 134, the disconnect coupling 60 ( Fig. 1 and Fig. 3) and the mode clutch 70 ( Fig. 1 and Fig. 2). The switching system 300 generally includes a driven actuator 302 and a spring-loaded switch isolation mechanism 304. The driven actuator 302 may be any type of electromechanical or electrohydraulic device having an output member movable between a first, or extended, position and a second, or retracted, position relative to an actuator housing 306 in response to an electrical control signal provided by the controller 68. In this non-limiting embodiment, the driven actuator 302 is a solenoid device.

[0040] Initially on Fig. 8, the separator sleeve 224 is shown in its separated position so that the driven spindle 220 is decoupled from the flange shaft 212. As noted, the separator sleeve 224 has internal spline teeth 226 that constantly mesh with external spline teeth 222 on the spindle 220. When the separator sleeve 224 is in its separated position, the clutch sleeve teeth 226 are disengaged from the clutch teeth 218 on the drive flange 216. The driven actuator 302, in this non-limiting embodiment, is disclosed as a solenoid having a plunger 310 that is linearly movable with respect to the actuator housing 306 between an extended and a retracted position. The plunger 310 is shown in its extended position so that a drive tab 312 ( Fig. 9) which is fixed at its terminal end, is arranged in a tubular guide sleeve 314 which is fixed in the axle housing 190. The spring-loaded switch isolation mechanism 304 generally includes an upper pivot lever 320, a lower pivot lever 322, and a spring assembly 324. The upper pivot lever 320 includes a drive segment 326 and a pivot segment 328. The drive segment 326 includes an opening (in Fig. 8 shown in phantom) 330 through which the plunger 310 extends, and an arcuate outer cam surface 332 against which the drive nose 312 engages.

[0041] The lower pivot lever 322 includes a spring retainer segment 340, a pivot segment 342, and a fork segment 344. The pivot segment 342 of the lower pivot lever 322 defines a pair of forked yokes that define a pivot cavity within which the pivot segment 328 of the upper pivot lever 320 is located. A pivot pin 350 extends through pivot openings formed in the forked yokes and a pivot bore formed in the pivot segment 328 of the upper pivot lever 320 to provide a pivotal connection therebetween. The opposite ends of the pivot pin 350 are retained in mounting bosses (not shown) formed in the axle housing 190. The fork segment 344 of the lower pivot lever 322 is arcuate and defines a pair of laterally spaced forks.A pair of drivers 352 are disposed in an annular groove 354 formed in the separating sleeve 224, and each driver 352 is pivotally attached to one of the forks via a pivot pin 356. A spring retainer segment 340 of the lower pivot lever 322 includes an opening (in . Fig. 8 shown in phantom) 360 and defines a stop side surface 362 configured to selectively engage a first or locking surface 364 formed on the drive segment 326 of the upper pivot lever 320.

[0042] The spring assembly 324 is shown including a spring pin or spring bolt 370 extending through the opening 360 in the spring retainer segment 340 of the lower pivot lever 322 and an opening (not shown) formed through the drive segment 326 of the upper pivot lever 320. A fastener, such as a locknut 372, directly connects a first end of the spring bolt 370 to the drive segment 326 of the upper pivot lever 320. A coil spring 374 is retained on the lower pivot lever 322 between a spring retainer feature 376 formed on a second end (i.e., a bolt head) of the spring bolt 370 and a second side surface 378 of the spring retainer segment 340.

[0043] Now on Fig. 9, the plunger 310 of the driven actuator 302 is shown from its extended position ( Fig. 8) into its retracted position relative to the actuator housing 306. If there is no locked tooth condition between the inner clutch teeth 226 on the separator sleeve 224 and the outer clutch teeth 218 on the drive flange 216, then the separator sleeve 224 is moved from its separated position ( Fig. 8) into their connected position ( Fig. 12). In particular, retraction of plunger 310 causes drive tab 312 to engage cam surface 332 and forcibly pivot upper pivot lever 320 about pivot pin 350. Spring 374 biases spring retainer segment 340 of lower pivot lever 322 into engagement with drive segment 326 of upper pivot lever 320, such that this pivotal movement of upper pivot lever 320 results in a corresponding pivotal movement of lower pivot lever 322 about pivot pin 350. Such pivotal movement of lower pivot lever 322 causes drivers 352, retained in annular groove 54, to move separator sleeve 224 axially into its connected position.

[0044] Fig. However, Figure 9 illustrates a locked tooth condition following actuation of actuator 302 to move plunger 310 to its retracted position. As shown by arrow 380, a drive tab 312 engages cam surface 332 and forcibly pivots the upper pivot lever in a first direction, or clockwise, as shown by arrow 382. Due to the locked tooth condition, separator sleeve 224 is prevented from moving axially, so that lower pivot lever 322 remains stationary with respect to upper pivot lever 320, thereby compressing spring 374 between bolt head 376 and second side surface 378 of spring retainer segment 340 on lower pivot lever 322.

[0045] Fig. Figure 10 illustrates that upon removal of the locked tooth condition between the coupling sleeve teeth 226 and the drive flange teeth 218, the spring 374 releases the stored spring force and forcibly pivots the lower pivot lever 322 about the pivot pin 350. The spring force applied along arrow 386 causes the fork segment 344 of the lower pivot lever 322 to forcibly move the separating sleeve 224 into its connected position due to the switching force shown by arrow 390. Fig. Figure 11 illustrates a continuation of this process, with spring 374 returning spring retainer segment 340 of lower pivot lever 322 into engagement with drive segment 326 of upper pivot lever 322, as shown by arrow 392. Fig. Figure 12 illustrates the completion of the switching process with the disconnect sleeve 224 fully in its connected position. To return the disconnect sleeve 224 to its disconnected position, the electromagnetic actuator 302 is then actuated to return the plunger 310 to its extended position.

[0046] Although actuator 302 is disclosed as an electromagnetic device with an axially extendable plunger 310, other configurations utilizing an axially translatable output to actuate isolation linkage mechanism 304 are contemplated and considered within the scope of the present disclosure. One such alternative may include a rotary-to-linear motion conversion device having a lead screw and drive nut driven by an electric motor. The present disclosure provides an arrangement utilizing an electromagnetic pull actuator 302 to smoothly drive a separator sleeve 224 via isolation linkage mechanism 304. When system 300 experiences a stalled circuit, mechanism 304 allows the solenoid to not be overloaded during its momentary actuation.Once the plunger has been moved to its retracted position, the electromagnetic excitation may cease because the preloaded (i.e., compressed) spring 374 provides the subsequent switching force required to move the separator sleeve 224 after the blocked condition is removed.

[0047] The Fig. 13 and Fig.14 illustrate a slightly modified version of the switching system 300, designated by the reference numeral 300'. It should be noted that components of the switching system 300' corresponding to those of the switching system 300 are designated hereinafter and in the drawings by a primed reference numeral. In this arrangement, the flanged shaft 212' surrounds an elongated driven spindle shaft 220' to which the output flange 232' is fixed. Bearings 400, 402 rotatably support the spindle shaft 220' relative to the flanged shaft 212'. A separator sleeve 224' is connected by a spline 404 for rotation with and axial movement on the driven spindle 220'. The separating sleeve 224' has a spur gear 406 configured to mate with the spur gear 408 on a drive flange portion 216' of the flange shaft 212' when the separating sleeve 224' is moved to its connected position.A return spring assembly 410 acts between the separating sleeve 224' and the driven spindle shaft 220' to normally bias the separating sleeve 224' toward its separating position. Lugs 420 extending from a pivot segment 342' of a lower pivot link 322' are hollow and allow pivot pins 350' to extend therethrough and through the opening 422 in a pivot segment 328' of an upper pivot lever 320'. As further shown, a drive lug 312' is attached to the terminal end of a plunger 310' and cooperates with a yoke portion 424 of a drive segment 326' on the upper pivot lever 320'. The drive nose 312' has projections 426 that are retained between yoke teeth 428 to accommodate misalignment and slight radial movement between the plunger 310' and the upper pivot lever 320'.

[0048] The switching system 300' functions similarly to the switching system 300 in that, upon energization of the solenoid 302' from its extended position to its retracted position, a pulling movement of the plunger 310' results in a pivoting movement of the upper pivot lever 320' about the pivot pin 350'. In an unblocked situation, such movement results in a coordinated pivoting movement of the lower pivot lever 322' about the pivot pin 350' to move the separator sleeve 224' axially into its connected position upon engagement of its spur gear teeth 406 with the spur gear teeth 408 on the drive flange 216'. In the case of a blocked switching condition, the spring assembly 324' is loaded by compression of the spring 374' due to the pivoting movement of the upper pivot lever 320' relative to the lower pivot lever 320'.After eliminating the blocked condition between the spur gear teeth 406, 408 and the clutch, the spring force is released and forcibly pivots the lower pivot lever 322' to perform the clutch switching operation.

Claims

[1] Coupling arrangement comprising: a first rotary member; a second rotary member; a clutch sleeve (94, 172) coupled for rotation to the first rotary member and axially movable between a first position and a second position, the clutch sleeve (94, 172) having first clutch teeth (96, 182) disengaged from second clutch teeth (98, 184) formed on the second rotary member when in its first position, and the first clutch teeth (96, 182) on the clutch sleeve (94, 172) engaging the second clutch teeth (98, 184) when in its second position; a power-operated clutch actuator (74, 139) having an output member movable between a first position and a second position; and a switch isolation mechanism (304) operatively connecting the output member to the clutch sleeve (94, 172) such that movement of the output member between its first and second positions causes corresponding movement of the clutch sleeve (94, 172) between its first and second positions, wherein the switch isolation mechanism (304) includes a biasing arrangement configured to permit movement of the output member from its first position to its second position while a locked tooth condition between the first and second clutch teeth (96, 182 / 98, 184) prohibits movement of the clutch sleeve (94, 172) from its first position to its second position, and wherein the biasing arrangement is subsequently released and forcibly moves the clutch sleeve (94, 172) from its first position to its second position when the locked tooth condition is removed,and wherein the biasing arrangement of the switch isolation mechanism (304) permits movement of the output member to its second position while the clutch arrangement is in the locked tooth state, characterized by , that the switch isolation mechanism (304) includes a lower pivot lever (322, 322'), wherein the lower pivot lever (322, 322') has a spring retainer segment (340), a pivot segment (342, 342') and a fork segment (344), wherein the fork segment (344) is coupled to the coupling sleeve (94, 172), and wherein the pivot segment (342, 342') and the fork segment (344) are in a pivotal relationship about a pivot pin (350, 350'), and that the shift isolation mechanism (304) further includes an upper pivot lever (320, 320'), the upper pivot lever (320, 320') being configured to include a drive segment (326, 326') that engages the output member of the power-operated clutch actuator (74, 139), and a pivot segment (328, 328'), and, that the pivot segment (342, 342') of the lower pivot lever (322, 322') is pivotally connected to the pivot segment (328, 328') of the upper pivot lever (320, 320'), and that the biasing arrangement of the switch isolation mechanism (304) includes a spring arrangement (324, 324') having a spring bolt (370) extending between the upper pivot lever (320, 320') and the lower pivot lever (322, 322') and a spring (374, 374') surrounding the spring bolt (370), and that pivoting movement between the upper pivot lever (320, 320') and the lower pivot lever (322, 322') loads the spring (374, 374') into a locked tooth condition and unloads the spring (374, 374') after the locked tooth condition is removed, thereby forcibly pivoting the lower pivot lever (322, 322') to move the coupling sleeve (94, 172). [2] The clutch assembly of claim 1, wherein the biasing assembly is configured to include a spring pin having a first end fixed to the drive segment (326, 326') of the upper pivot lever (320, 320') and a second end defining a spring retainer, and a coil spring surrounding the spring pin and having a first end acting on the spring retainer segment (340) of the lower pivot lever (322, 322') and a second end acting on the spring retainer at the second end of the spring pin. [3] A clutch assembly according to claim 2, wherein an intermediate portion of the spring pin extends through an opening formed in the spring retainer segment (340) of the lower pivot lever (322, 322'). [4] The clutch assembly of claim 2, wherein the power-operated clutch actuator (74, 139) is a solenoid having a linearly movable plunger (310, 310') acting as the output member, the first position of the plunger (310, 310') being an extended position relative to the solenoid such that the switch isolation mechanism (304) positions the clutch sleeve (94, 172) in its first position, and the second position of the plunger (310, 310') being a retracted position relative to the solenoid such that the plunger (310, 310') engages the drive segment (326, 326') of the upper pivot lever (320, 320') and causes pivotal movement of the upper and lower pivot levers (320 / 322). [5] A clutch assembly according to claim 4, wherein pivotal movement of the lower pivot lever (322, 322') is inhibited during the locked tooth condition so that the coil spring (374) is loaded by pivotal movement of the upper pivot lever (320) relative to the lower pivot lever (322, 322'), and wherein the coil spring (374) is unloaded in response to the removal of the locked tooth condition so that it forcibly pivots the lower pivot lever (322, 322') to move the clutch sleeve (94, 172) from its first position to its second position. [6] A clutch assembly according to claim 4, wherein a drive lug (312) is provided on the terminal end of the plunger (310, 310') and is configured to engage a cam surface (332) formed on the drive segment (326, 326') of the upper pivot lever (320, 320'). [7] A clutch assembly according to claim 6, wherein the drive nose (312, 312') is slidably movable relative to the stationary tubular guide housing. [8] Clutch arrangement according to claim 1, wherein the clutch arrangement is a mode clutch in a power take-off unit. [9] Clutch assembly according to claim 1, wherein the clutch assembly is a disconnect clutch in a disconnect coupling.

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