CN106687716A - Compact electronically controlled front wheel drive torque vectoring system with single or dual axis modulation - Google Patents

Abstract

A torque vectoring system constructed in accordance with one example of the present disclosure includes a differential, a first drive shaft, a second drive shaft, a first gear train and a second gear train. The first drive shaft is operably coupled to the differential. The second drive shaft is operably coupled to the differential. The first gear train is selectively driven by the differential and is configured to selectively supply a speed application from the differential to one of the first and second drive axles. The second gear train is selectively driven by the differential and is configured to selectively supply a speed reduction from the differential to one of the first and second drive shafts.

Description

Compact electronically controlled front wheel drive torque vectoring with single or dual axis modulation system

Cross References to Related Applications

This application claims U.S. Patent Application No. 62/029,045, filed July 25, 2014, U.S. Patent Application No. 62/061,317, filed October 8, 2014, U.S. Patent Application No. 62/061,317, filed August 22, 2014 Application No. 62/040,535, filed November 12, 2014 U.S. Patent Application No. 62/078,741, filed December 10, 2014 U.S. Patent Application No. 62/090,081, filed August 22, 2014 U.S. Patent Application No. 62/040,543, filed, and benefit of U.S. Patent Application No. 62/085,786, filed December 1, 2014. The disclosures of the above applications are incorporated herein by reference.

technical field

The present disclosure relates generally to differential assemblies, and more particularly, to electronic limited slip differentials.

Background technique

A differential is provided on the vehicle to allow the outer drive wheel to rotate faster than the inner drive wheel during cornering as both drive wheels continue to receive power from the engine. While differentials are useful in cornering, they can allow a vehicle to lose traction in, for example, snow or mud or other slippery media. If either drive wheel loses traction, it will spin at a high rate, while the other wheel may not spin at all. To overcome this, limited slip differentials were developed to transfer power from the driving wheels that had lost traction and were spinning to the non-rotating drive wheels. Typically, clutch packs may be disposed between side gears of the differential and adjacent surfaces of a gearbox of the differential. A clutch pack is operable to limit relative rotation between the gearbox and the side gears. Additionally, it is often desirable to apply torque vectoring, in which the power directed to the drive wheels is varied.

The background description provided herein is for the purpose of generally presenting the context of the disclosure. To the extent described in this Background section, the work of the inventors presently referred to, and aspects that may not otherwise be described as prior art at the time of filing, are neither expressly nor implicitly admitted as subject to the present disclosure existing technology.

Contents of the invention

A torque vectoring system constructed in accordance with one example of the present disclosure includes a differential, a first drive shaft, a second drive shaft, a first gear train, and a second gear train. The first drive shaft is operatively coupled to the differential. The second drive shaft is operatively coupled to the differential. The first gear train is selectively driven by the differential and is configured to selectively supply speed application from the differential to one of the first drive shaft and the second drive shaft . The second gear train is selectively driven by the differential and is configured to selectively supply a speed reduction from the differential to one of the first drive shaft and the second drive shaft one.

According to additional features, the torque vectoring system may further include a first clutch and a second clutch. The first clutch may be configured to selectively couple the first gear train to the first shaft during an acceleration request. The second clutch may be configured to selectively couple the second gear train to the first shaft during a deceleration request. The actuator may be configured to selectively close one of the first clutch or the second clutch. The actuator may comprise a lever arm. The actuator may be configured to (i) move the lever arm in a first direction to close the first clutch and (ii) move the lever arm in a second direction to close the second clutch.

According to other features, the first clutch includes a first clutch pack positioned in a first clutch basket. The second clutch includes a second clutch pack positioned in a second clutch basket. The actuators may be configured to automatically engage respective gear train paths to modulate the first drive shaft and the second drive shaft based on the requirements of vehicle driving conditions. In one configuration the actuator includes a ball screw assembly including a motor isolating the shaft in one of a first direction and a second direction. A first thrust plate may be configured to transfer force from the lever arm to the first clutch pack. The second thrust plate may be configured to transfer force from the lever arm to the second clutch pack. The lever arm may be positioned between the first clutch pack and the second clutch pack such that simultaneous movement of the lever arm in the first direction and the second direction is prevented.

According to still other features, the torque vectoring system can further include a countershaft drive gear set and a driven gear set. The countershaft drive gear set may have a countershaft gear meshing with a mating countershaft gear. The driven gear set may have a first driven gear and a second driven gear. The countershaft mating gear and the first driven gear are mounted to rotate simultaneously with the gear shaft. The second driven gear is fixed to rotate simultaneously with the other of the first drive shaft and the second drive shaft.

According to additional features, the torque vectoring system may include an electromechanical clutch having a clutch pack, a thrust plate, and a ball screw assembly. The clutch pack has first and second sets of clutch plates. The thrust plate is movably positioned adjacent the clutch pack. The ball screw assembly is engaged with the thrust plate. The ball screw is operable to move the thrust plate to press the first and second sets of clutch plates together and thereby lock the clutch. The thrust plate is pivotally movable. A thrust bearing is positioned between the thrust plate and the first and second sets of clutch plates. A torsion spring engages the shaft of the ball screw assembly and is operable to store energy when the shaft is rotated by the motor of the ball screw assembly.

The torque vectoring system may also include a lever mechanism positioned between the ball screw assembly and the thrust plate. The ball screw assembly defines a modular packaging layout and accommodates additional design features. A controller is operable to control the motor, the controller being stored in memory and operable to execute an actuator control algorithm that reduces the likelihood of mechanical backlash and frictional hysteresis.

Description of drawings

The present disclosure will be more fully understood from the detailed description and accompanying drawings, in which:

1-5 illustrate an electronically controlled torque vectoring system configured for single-axis modulation according to one example of the present disclosure;

1 is a schematic diagram of an electronically controlled torque vectoring system constructed and configured for single-axis modulation in accordance with one example of the present disclosure;

2A is a schematic diagram of the driven wheels during a right turn when the electronically controlled torque vectoring system (i) adds understeer with the first clutch closed and (ii) adds positive torque with an accelerating gear train;

Fig. 2B is a schematic diagram of the driven wheel of Fig. 2A;

3A is a schematic diagram of the driven wheels during a left turn when the electronically controlled torque vectoring system (i) adds oversteer with the second clutch closed and (ii) adds negative torque with a reduction gear train;

Fig. 3B is a schematic diagram of the driven wheel of Fig. 3A;

4A is a schematic diagram of driven wheels showing power flow of an eLSD of an electronically controlled torque vectoring system;

Fig. 4B is a schematic diagram of the driven wheel of Fig. 4A;

5 is a schematic diagram of a torque modulation system constructed in accordance with another example of the present disclosure and having a dual clutch upstream of the gear train for a smaller clutch set and actuation force;

6A-8B illustrate an electronically controlled torque vectoring system configured for biaxial modulation according to one example of the present disclosure;

6A is a schematic diagram of an electronically controlled torque vectoring system constructed in accordance with one example of the present disclosure and shown having a main flow path and configured for biaxial modulation;

Fig. 6B is a schematic diagram of the driven wheel of Fig. 6A;

7A is a schematic diagram of a driven wheel during a left turn when an electronically controlled torque vectoring system applies a gear train path using a first speed to add torque to an outer driven wheel;

Fig. 7B is a schematic diagram of the driven wheel of Fig. 7A;

8A is a schematic diagram of a driven wheel during a right turn when the electronically controlled torque vectoring system uses a second reduction gear train path to add torque to the outside driven wheel;

Fig. 8B is a schematic diagram of the driven wheel of Fig. 8A;

9 is a cross-sectional view of a differential assembly constructed in accordance with another example of the present disclosure;

Figure 10 is a view taken along perspective arrow 10-10 in Figure 9; and

11 is an exploded view of an electromechanical clutch configured according to another example of the present disclosure.

detailed description

An electronically controlled torque vectoring system constructed in accordance with one example of the present disclosure is shown and generally identified by the reference numeral 10 . The electronically controlled torque vectoring system 10 can provide a full range of effective torque management functions. The electronically controlled torque vectoring system 10 may provide a seamless transition between electronically controlled limited slip mode (eLSD) and torque vectoring modes. An example of an electronically controlled torque vectoring system 10 may include a bolt-on modular design with minimal impact to the original equipment manufacturer. The torque vectoring system 10 may be packaged into a power take off (PTO) space for an all wheel drive vehicle.

Referring now to FIG. 1 , an electronically controlled torque vectoring system 10 may include a differential 12 and a two-way electromechanical clutch 16 . Electronically controlled torque vectoring system 10 may transmit rotational power to shafts 20 and 22 . As shown in FIG. 2 , shafts 20 , 22 may drive wheels 24 , 26 . As can be appreciated from the following discussion, electronically controlled torque vectoring system 10 may provide a torque vectoring system with single axis modulation.

The differential 12 may include a ring gear 28 , a case 30 , a pin 32 , and a plurality of pinions, such as pinions 36 , 38 . Ring gear 28 is rotatable about axis 40 by a vehicle power source, such as an engine and a drive shaft (not shown). Ring gear 28 and case 30 may be fixed for rotation together. Pin 32 may be mounted in case 30 and rotate with case 30 and ring gear 28 about axis 40 . The pinions 36 , 38 may respectively be mounted on the pins 32 for rotation about the respective pins 32 . Pinions 36 , 38 may mesh with side gears 42 and 44 . Side gear 42 may be fixed for rotation with shaft 20 and side gear 44 may be fixed for rotation with shaft 22 .

The two-way clutch 16 may include a first clutch pack 56 , a second clutch pack 58 , and an actuator 60 . The first clutch pack 56 may be positioned in a first clutch basket 62 . The second clutch pack 58 may be positioned in a second clutch basket 63 . Actuator 60 may be a single actuator configured to automatically engage a corresponding gear train path for modulating the drive shaft ( FIGS. 2 or 3 ) based on the requirements of vehicle driving conditions. As used herein, the term "modulation" is used to refer to moving the clutch pack 56, 58 to a fully locked state, a fully open state, one or more operating states between fully locked and fully open.

The actuator 60 may include a ball screw assembly 64 , a lever arm 66 , a first thrust plate 68 , and a second thrust plate 70 . Ball screw assembly 64 may be operable to pivot lever arm 66 about pivot axis 72 in first and second opposite angular directions. Ball screw assembly 64 may include a motor 74 , a shaft 76 , and a nut 78 . The motor 74 can rotate the shaft 76 in first and second opposite rotational directions. Motor 74 may include an internal reduction gear set and one or more speed sensors, current sensors, or both. The nut 78 is movable in a first linear direction in response to rotation of the shaft 76 in the first rotational direction. The nut 78 is movable in a second linear direction opposite the first linear direction in response to rotation of the shaft 76 in the second rotational direction. The distal end 80 of the lever arm 66 may form a yoke that partially surrounds one of the shaft 76 and the nut 78 .

In operation, motor 74 may rotate shaft 76 in a first rotational direction. In response, nut 78 may move in a linear direction indicated at 82 . It should be noted that the distance traveled by the nut 78 may be small. The distal end 80 of the lever arm 66 can thus be urged to pivot about the pivot axis 72 , exerting a force on the first thrust plate 68 . Additionally, force may be transmitted to the clutch pack 56 via the first thrust plate 68 , closing the clutch pack 56 (incrementally).

In operation, motor 74 may also rotate shaft 76 in a second rotational direction. In response, nut 78 may move in a linear direction indicated at 84 . It should be noted that the distance traveled by the nut 78 may be small. The distal end 80 of the lever arm 66 can thus be urged to pivot about the pivot axis 72 , exerting a force on the second thrust plate 70 . Additionally, force may be transferred to the clutch pack 58 via the second thrust plate 70 , closing the clutch pack 58 (incrementally).

It should be noted that other forms of actuators providing bi-directional actuation may be employed in other examples of the invention. It should also be noted that linear actuators other than rotary motors and force multiplying mechanisms other than ball screw assemblies may be included in other examples of the present disclosure. For example, one or more fluid cylinders may be employed to move the distal end 80 of the lever arm 66 .

The electronically controlled torque vectoring system 10 may also include a countershaft drive gearset, generally designated 82 , and including a countershaft gear 84 that meshes with a countershaft mating gear 86 . Countershaft gear 84 may be fixed for rotation with differential case 30 . A first or booster gear train, generally designated 92 , may include a first basket gear 94 meshing with a first drive gear 96 . A second or reduction gear train, generally designated 102 , may include a second basket gear 104 meshing with a second drive gear 106 . The countershaft mating gear 86 , the first drive gear 96 and the second drive gear 106 may all be fixed for simultaneous rotation with the gear shaft 108 .

2 and 3 show the electronically controlled torque vectoring system 10 operating in torque vectoring, right turn mode (FIG. 2) and torque vectoring left turn mode (FIG. 3). In the torque vectoring mode, the electronically controlled torque vectoring system 10 can (i) close the first clutch set 56 to generate positive torque with the overdrive gear train 92 ( FIG. 2 ), or (ii) close the second clutch set 58 to produce positive torque with the The reduction gear train 102 produces negative torque (FIG. 3). Notably, with the current configuration, the actuator 60 and ball screw assembly 64 can only close (or partially close) one of the clutch packs 56 , 58 . Referring to FIG. 2 , a torque path 110 can be created from countershaft gear 84 to countershaft mating gear 86 through first drive gear 96 , first basket gear 94 (first clutch basket 62 ), first clutch pack 56 and shaft 20 . In the example shown, the accelerating gear train provides a gear ratio of 1.1. To explain further, for every rotation of countershaft gear 84 , shaft 20 will rotate 1.1 times. Other ratios are contemplated. Referring to FIG. 3 , the countershaft gear 84 can be generated along the gear shaft 108 through the second drive gear 106 , the second basket gear 104 (second clutch basket 63 ), the second clutch pack 58 and the shaft 20 from the countershaft gear 84 to the countershaft mating gear. 86 torque path 120 . In the example shown, the reduction gear train provides a gear ratio of 0.9. To explain further, for every revolution of countershaft gear 84 , shaft 20 will rotate 0.9 times. Other ratios are contemplated. For the torque vectoring function, the two-way clutch 16 automatically engages the first clutch set 56 or the second clutch set 58 to accelerate the outer wheel or the inner wheel based on the driving conditions. For eLSD operation, either the first clutch set 56 or the second clutch set 58 may be modulated to provide braking to the identified wheels.

FIG. 4 shows a schematic view of the driven wheels showing the power flow of the eLSD of the electronically controlled torque vectoring system 10 . Even in the locked state (left and right driven wheels rotating at the same speed), the two-way clutch 16 still slips due to the gear ratio. During operation, when the left wheel is slipping, the first clutch 56 ( FIG. 1 ) may be engaged to utilize the reduction path clutch. When the right wheel is slipping, the second clutch 58 ( FIG. 1 ) can be engaged to utilize the acceleration path clutch.

FIG. 5 is a schematic diagram of a torque modulation system 210 constructed according to another example of the present disclosure and having a dual clutch 216 upstream of a first gear train 230 and a second gear train 232 . Dual clutch 216 may include a first clutch 236 and a second clutch 238 . In one arrangement, differential 212 may be configured to drive load 240 . Differential case 230 may be configured to drive load 240 through dual clutch 216 and first and second gear trains 230 and 232 . The torque modulation system 210 may be used in smaller clutch pack and actuation force configurations.

An electronically controlled torque vectoring system constructed in accordance with another example of the present disclosure is shown and generally identified by the reference numeral 310 . The electronically controlled torque vectoring system 310 can provide a full range of effective torque management functions. The electronically controlled torque vectoring system 310 may provide a seamless transition between electronically controlled limited slip mode (eLSD) and torque vectoring modes. An example of an electronically controlled torque vectoring system 310 may include a bolt-on modular design with minimal impact to the original equipment manufacturer. In one configuration, torque vectoring system 310 may be configured for front wheel drive applications. In other examples, the torque vectoring system 310 may be packaged into a power take off (PTO) space for an all wheel drive vehicle.

Referring now to FIGS. 6A and 6B , an electronically controlled torque vectoring system 310 may include a differential 312 and a two-way electromechanical clutch 316 . Electronically controlled torque vectoring system 310 may transmit rotational power to shafts 320 and 322 . As shown in FIGS. 6A and 6B , shafts 320 , 322 may drive wheels 324 , 326 . As will be appreciated from the following discussion, electronically controlled torque vectoring system 310 may provide a torque vectoring system with dual axis modulation.

The differential 312 may include a ring gear 328 , a case 330 , a pin 332 , and a plurality of pinions, such as pinions 336 , 338 . Ring gear 328 may be driven to rotate about axis 340 by a vehicle power source, such as an engine and a drive shaft (not shown). Ring gear 328 and case 330 may be fixed for rotation together. Pin 332 may be mounted in case 330 and rotate with case 330 and ring gear 328 about axis 340 . The pinions 336 , 338 may be respectively mounted on the pin 332 for rotation about the respective pin 332 . Pinions 336 , 338 may mesh with side gears 342 and 344 . Side gear 342 may be fixed for rotation with shaft 320 and side gear 344 may be fixed for rotation with shaft 322 .

The two-way clutch 316 may include a first clutch pack 356 , a second clutch pack 358 , and an actuator 360 . The first clutch pack 356 may be positioned in a first clutch basket 362 . The second clutch pack 358 may be positioned in a second clutch basket 363 . Actuator 360 may be a single actuator configured to automatically engage a corresponding gear train path for modulating drive shafts 320, 322 (FIGS. 7A or 7B) based on the requirements of vehicle driving conditions. As used herein, the term "modulation" is used to refer to moving the clutch pack 356, 358 to a fully locked state, a fully open state, one or more operating states between fully locked and fully open.

The actuator 360 may include a ball screw assembly 364 , a lever arm 366 , a first thrust plate 368 , and a second thrust plate 370 . Ball screw assembly 364 may be operable to pivot lever arm 366 about pivot axis 372 in first and second opposite angular directions. Ball screw assembly 364 may include a motor 374 , a shaft 376 , and a nut 378 . The motor 374 can rotate the shaft 376 in first and second opposite rotational directions. Motor 374 may include an internal reduction gear set and one or more speed sensors, current sensors, or both. Nut 378 is movable in a first linear direction in response to rotation of shaft 376 in a first rotational direction. The nut 378 is movable in a second linear direction opposite the first linear direction in response to rotation of the shaft 376 in the second rotational direction. The distal end 380 of the lever arm 366 may form a yoke that partially surrounds one of the shaft 376 and the nut 378 .

In operation, motor 374 may rotate shaft 376 in a first rotational direction. In response, nut 378 may move in a linear direction. It should be noted that the distance traveled by nut 378 may be small. The distal end 380 of the lever arm 366 can thus be urged to pivot about the pivot axis 372 , exerting a force on the first thrust plate 368 . Additionally, force may be transferred to clutch pack 356 via first thrust plate 368 , closing clutch pack 356 (incrementally).

In operation, motor 374 may also rotate shaft 376 in a second rotational direction. In response, nut 378 may move in a linear direction. It should be noted that the distance traveled by nut 378 may be small. The distal end 380 of the lever arm 366 can thus be urged to pivot about the pivot axis 372 , applying a force to the second thrust plate 370 . Additionally, force may be transferred to the clutch pack 358 via the second thrust plate 370 , closing the clutch pack 358 (incrementally).

It should be noted that other forms of actuators providing bi-directional actuation may be employed in other examples of the invention. It should also be noted that linear actuators other than rotary motors and force multiplying mechanisms other than ball screw assemblies may be included in other examples of the present disclosure. For example, one or more fluid cylinders may be employed to move the distal end 80 of the lever arm 66 .

The electronically controlled torque vectoring system 310 may also include a countershaft drive gearset generally designated 382 and including a countershaft gear 384 that meshes with a countershaft mating gear 386 . Countershaft gear 384 may be fixed for rotation with differential case 330 . The torque vectoring system 310 may additionally include a driven gear set, generally designated 388 , including a first driven gear 389 and a second driven gear 390 . The second driven gear 390 may be fixed to rotate together with the driving shaft 320 .

With particular reference to Figure 6B, the main power flow path 391 will be described. Active power flow path 391 may be used during normal driving conditions. Active power flow path 391 is followed when differential 312 is operating as an open differential, where power is delivered to first and second shafts 320 and 322 in various ratios based on operating conditions (and without modulation from two-way clutch 316 ). Torque from differential case 330 is transmitted (i) from side gear 342 , through countershaft gear set 382 , along gear shaft 408 , through driven gear set 388 , to shaft 320 , and (ii) from side gear 344 to shaft 322.

A first or booster gear train, generally designated 392 , may include a first basket gear 394 that meshes with a first drive gear 396 . A second or reduction gear train (collectively designated 402 ) may include a second basket gear 404 meshing with a second drive gear 406 . Countershaft mating gear 386 , first drive gear 396 , and second drive gear 406 may all be fixed for simultaneous rotation with gear shaft 408 .

FIG. 7A shows the electronically controlled torque vectoring system 310 operating in the torque vectoring, left turn mode. In this mode, electronically controlled torque vectoring system 310 can close second clutch pack 358 to generate positive torque with overdrive gear train 392 . In FIG. 8A , electronically controlled torque vectoring system 310 is shown operating in a torque vectoring, right turn mode. In this mode, the electronically controlled torque vectoring system 310 can close the first clutch pack 356 to generate negative torque with the reduction gear train 402 .

Notably, with the current configuration, the actuator 360 and ball screw assembly 364 can only close (or partially close) one of the clutch packs 356 , 358 . Referring to 7A, the countershaft gear 384 to countershaft mating along gear shaft 408 through first drive gear 396 , first basket gear 394 (second clutch basket 363 ), second clutch pack 358 and second shaft 322 can occur Torque vectoring of gear 386 vectorizes torque path 410 . In the example shown, the speedup gear train 392 provides a gear ratio of 1.1. To explain further, for every rotation of countershaft gear 384 , second shaft 322 will rotate 1.1 times. Other ratios are contemplated.

Referring to FIG. 8A , there can be produced along gear shaft 408 from countershaft gear 384 to countershaft Torque vectoring in conjunction with gear 386 vectorizes torque path 420 . In the example shown, reduction gear train 402 provides a gear ratio of 0.9. To explain further, for every rotation of countershaft gear 384 , second shaft 322 will rotate 0.9 times. Other ratios are contemplated. For torque vectoring functions, the two-way clutch 316 automatically engages the first clutch set 356 or the second clutch set 358 to accelerate or decelerate the second shaft 322 based on driving conditions. For eLSD operation, either the first clutch set 356 or the second clutch set 358 may be modulated to provide braking to the identified wheels.

During operation, when the left wheel is slipping, the second clutch 358 can be engaged (FIG. 7A) to apply the path clutch with speed (transmitting more torque to the right wheel). To explain further, torque vectoring may be used to vectorize the torque path 410 (speed application) by transferring torque from the first drive gear 396 to the drive shaft 322 through the clutch basket 363 . When the right wheel is slipping, the first clutch 356 can be engaged (FIG. 8A) to utilize the deceleration path clutch (transmitting more torque to the left wheel). Explaining further, torque vectoring may be used to vectorize the torque path 420 (speed reduction) by transferring torque from the second drive gear 406 to the drive shaft 322 through the clutch basket 362 . In this regard, the first clutch 356 and the second clutch 358 are used to provide an appropriate amount of slip for control of the speed and torque requests of the dual shafts 320 , 322 . The coaxial design of the electronically controlled torque vectoring system 310 provides a compact radial size suitable for receipt in tight packing situations.

The present teachings generally include electromechanical clutch actuation systems, which can be shown to provide high mechanical advantage, relatively compact packaging, better controllability, and combinations thereof. The actuation system may include a motor and a reduction gear set. The actuation system may include one or more motor speed sensors or one or more current sensors or both. The actuation system may also include a ball screw interacting with the nut for converting rotational motion to linear motion during operation. The actuation system may also include a lever arm and linkage to apply axial force to the differential clutch pack. The lever arm and linkage mechanism can be shown to provide a relatively high mechanical advantage mechanism that is robust to changes in temperature and wear due to use.

9 and 10 are views of a differential assembly 510 constructed in accordance with another example of the present disclosure. The differential assembly 510 may include a case 512 and a cover 514 . Ring gear 516 may be positioned in case 512 . Ring gear 516 may be driven in rotation by a drive shaft (not shown) driven in rotation by a motor. Ring gear 516 may be fixed for rotation with housing 518 . A plurality of pins, such as pin 520 , may be mounted in housing 518 . One or more pinions (eg, pinions 522, 524) may be mounted on each pin for rotation relative to the corresponding pin. Each pinion can mesh with a side gear 526 , 528 . Shafts 530 , 532 may be fixed for rotation with side gears 526 , 528 .

The differential assembly 510 may include an electronic limited slip assembly with an electromechanical clutch 534 , as shown in FIG. 9 . Clutch 534 may be operatively disposed between housing 518 and side gear 526 to selectively lock housing 518 and side gear 526 . Clutch 534 is selectively engageable to limit slippage of the associated shaft 530 relative to the housing 518 and thus relative to the rotational input of the differential assembly 510 .

Clutch 534 may include a clutch pack 536 . Clutch pack 536 may include a first set of clutch plates, such as clutch plates 538 , fixed for rotation with housing 518 . Clutch pack 536 may also include a second set of clutch plates, such as clutch plates 540 , fixed for rotation with side gear 526 . Clutch 534 may also include one or more pins, such as pins 542 and 544 , that pass through housing 518 . Pins 542, 544 may transmit force to press first and second sets of clutch plates 538, 540 against each other, locking housing 518 and side gear 526 together.

Clutch 534 may also include an actuation device 546 to transmit force to pins 542 , 544 . The actuation device 546 may include a thrust plate 548 . A thrust bearing 550 having races 552 , 554 may be disposed between thrust plate 548 and pins 542 , 544 . It should be noted that other examples of the present disclosure may be arranged such that the thrust bearing is disposed between the thrust plate and the clutch plate, omitting the pin.

The actuation device 546 may also include a lever mechanism having a lever arm 556 operable to push the thrust plate 548 against the pins 542 , 544 . The lever arm 556 may include a contact pad portion 558 that contacts the thrust plate 548 . Lever arm 556 may be mounted in box 512 for pivotal movement about pivot axis 560 .

Actuation device 546 may also include a ball screw assembly 562 operable to pivot lever arm 556 about pivot axis 560 to push thrust plate 548 against pins 542 , 544 and thereby engage clutch 534 . Ball screw assembly 562 may include motor 564 , shaft 566 , and nut 568 . The motor 564 can rotate the shaft 566 in first and second opposite rotational directions. Motor 564 may include an internal reduction gear set and one or more speed sensors, current sensors, or both. Nut 568 is movable in a first linear direction in response to rotation of shaft 566 in a first rotational direction. The nut 568 is movable in a second linear direction opposite the first linear direction in response to rotation of the shaft 566 in the second rotational direction. The distal end 570 of the lever arm 556 may form a yoke that partially surrounds the shaft 566 and abuts the nut 568 .

In operation, motor 564 may rotate shaft 566 in a first rotational direction. In response, nut 568 may move in a linear direction indicated at 572 . It should be noted that the distance traveled by the nut 568 may be small. Distal end 570 of lever arm 556 may thereby be urged to pivot about pivot axis 560 , applying a force against thrust plate 518 through contact pad portion 558 . Additionally, force may be transmitted through the thrust plate 518 to the pins 542 , 544 and cause the first and second sets of clutch plates 538 , 540 to be compressed together, locking the clutch 534 .

The differential assembly 510 may include a controller 576 operable to control the motor 564 . The controller 576 may store in memory and execute actuator control algorithms to reduce the possibility of mechanical backlash and frictional hysteresis. Controller 576 may be in communication with position and current feedback, such as position and current sensors disposed within motor 564 or external to motor 564 .

A torsion spring 574 may be coupled to the shaft 566 . Torsion spring 574 may coil and store energy when motor 564 rotates the shaft in the first rotational direction. When motor 564 is disengaged, torsion spring 574 may unwind and release energy, urging shaft 566 to rotate in a second rotational direction, moving nut 568 in a direction opposite to direction 572 . This movement may unlock clutch 534 .

The illustrated example reveals the modular packaging/layout and accommodates additional design features of the torque management unit for the differential assembly 10 . It will be appreciated that the features described in Figures 9 and 10 may be incorporated into the examples described in Figures 1-8B. Similarly, features described in the examples of FIGS. 1-8B may be incorporated into FIGS. 9 and 10 . Ball screw assembly 562 may be positioned in any of a number of different positions relative to case 512 . Additionally, additional structures that provide other functionality may be mounted to or used with ball screw assembly 562 . It should also be noted that linear actuators other than rotary motors and force multiplying mechanisms other than ball screw assemblies may be included in other examples of the present disclosure. For example, one or more fluid cylinders may be employed to move the distal end 570 of the lever arm 556 .

Referring now to FIG. 11 , an electromechanical clutch for an electronic limited slip differential according to another example of the present disclosure is shown and generally identified by the reference numeral 616 . Electromechanical clutch 616 may be configured to operate with a differential, such as differentials 12 , 212 , 312 , and 512 described herein. The electromechanical clutch 616 may include a first lever arm 620, a second lever arm 630, a retaining collar 634, a needle bearing 640, a pair of bearing races 644, a needle thrust bearing 648, a snap ring 650, a clutch pack 656, and a clutch pack 656. Actuator assembly 660. The first and second lever arms 620 , 630 may be pivotably coupled at a pivot pin 661 .

Clutch pack 656 may be positioned in clutch basket 662 . The clutch pack may include first and second sets of clutch plates 664 , 668 . The actuator assembly 660 may be configured to rotatably pivot the first lever arm 620 about a pivot pin 661 relative to the second lever arm 630 . The first lever arm 620 is configured to push the first and second sets of clutch plates 664 , 668 together to thereby lock the electromechanical clutch 616 . Movement of the first lever arm 620 away from the second lever arm 630 selectively engages the clutch pack 656 to modulate the drive shaft (see drive shafts 20 , 22 of FIG. 2B ) based on the drive conditions.

The actuator assembly 660 may include a ball screw assembly 670 operable to pivot the first lever arm 620 relative to the second lever arm 630 . The actuator assembly 660 can move the first and second lever arms 620, 630 relative to each other to modulate the clutch pack 656 between a fully locked state, a fully open state, and operational states between the fully locked and fully open states. In the particular example shown, the first lever arm 620 pivots away from the second lever arm 630 during clutch engagement to modulate the clutch pack 656 toward the fully locked state. Similarly, the first lever arm 620 pivots toward the second lever arm 630 during clutch disengagement.

Ball screw assembly 670 includes a motor 672 , a nut 674 , and a shaft 676 . Motor 672 is configured to rotate shaft 676 . Shaft 676 includes a worm or worm wheel 680 having threads 682 that threadingly engage complementary threads 684 defined in nut 674 . Rotation of the worm 680 moves the nut 674 along the axis of the worm 680 , causing pivoting of the first lever arm 620 relative to the second lever arm 630 .

Retaining collar 634 is coupled to the differential case (see, eg, case 330 , FIG. 7B ). Second lever arm 630 is configured to act on retaining collar 634 during actuation of electromechanical clutch 616 . This configuration limits axial case stress from the differential. To explain further, the actuation force reacts against the retaining ring 634 and the clutch pack 656 . Actuation force is not transferred to the axles through the differential. Instead, the actuation force is self-contained within the clutch pack 616 . The scissor configuration of the first and second lever arms 620, 630 eliminates reaction forces to the axial housing. As the differential rotates, thrust bearing 640 allows the differential to rotate, but also allows clutch actuation forces to react axially against retaining ring 634 .

The foregoing description of examples has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular example are generally not limited to that particular example, but, where applicable, are interchangeable and can be used in a selected example, even if not specifically shown or described. The same can also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of this disclosure.

Claims (20)

1. A torque vectoring system comprising: differential; a first drive shaft operatively coupled to the differential; a second drive shaft operatively coupled to the differential; A first gear train selectively driven by the differential and configured to selectively supply speed application from the differential to the first drive shaft and the second one of the drive shafts; and a second gear train selectively driven by the differential and configured to selectively supply a speed reduction from the differential to the first drive shaft and the second One of the two drive shafts. 2. The torque vectoring system of claim 1, further comprising: a first clutch configured to selectively couple the first gear train to the first shaft during an acceleration request; and A second clutch configured to selectively couple the second gear train to the first shaft during a deceleration request. 3. The torque vectoring system of claim 2, further comprising: An actuator configured to selectively close one of the first clutch or the second clutch. 4. The torque vectoring system of claim 3, wherein said actuator further comprises: a lever arm, and wherein the actuator is configured to (i) move the lever arm in a first direction to close the first clutch and (ii) move the lever arm in a second direction to close the Second clutch. 5. The torque vectoring system of claim 4, wherein said first clutch includes a first clutch pack positioned in a first clutch basket, and wherein said second clutch includes a clutch pack positioned in a second clutch basket. Second clutch group. 6. The torque vectoring system of claim 5, wherein the actuator is configured to automatically engage a corresponding gear train path to modulate the first drive shaft and the second drive shaft based on the requirements of vehicle driving conditions. axis. 7. The torque vectoring system of claim 6, wherein the actuator comprises a ball screw assembly including a motor isolating the shaft in one of a first direction and a second direction . 8. The torque vectoring system of claim 6, further comprising: A first thrust plate configured to transfer force from the lever arm to the first clutch pack. 9. The torque vectoring system of claim 8, further comprising: A second thrust plate configured to transfer force from the lever arm to the second clutch pack. 10. The torque vectoring system of claim 7, wherein said lever arm is positioned between said first clutch pack and said second clutch pack such that said lever arm is prevented from moving between said first direction and said second clutch pack. Simultaneously move in the second direction. 11. The torque vectoring system of claim 1, further comprising (i) a countershaft drive gearset having a countershaft gear meshing with a countershaft mating gear, and (ii) a a driven gear set having a first driven gear and a second driven gear, wherein the countershaft mating gear and the first driven gear are mounted to rotate simultaneously with the gear shaft, and the second Two driven gears are fixed to rotate simultaneously with the other of the first drive shaft and the second drive shaft. 12. The torque vectoring system of claim 1 further comprising: An electromechanical clutch, the electromechanical clutch comprising: a clutch pack having first and second sets of clutch plates; a thrust plate movably positioned adjacent the clutch pack; and A ball screw assembly engaged with the thrust plate, the ball screw being operable to move the thrust plate to compress the first and second sets of clutch plates together and thereby lock the clutch. 13. The torque vectoring system of claim 12, wherein the thrust plate is further defined as being pivotally movable. 14. The torque vectoring system of claim 12, further comprising: a thrust bearing positioned between the thrust plate and the first and second sets of clutch plates; and A torsion spring engaged with the shaft of the ball screw assembly and operable to store energy when the shaft is rotated by the motor of the ball screw assembly. 15. The torque vectoring system of claim 14, further comprising: A lever mechanism positioned between the ball screw assembly and the thrust plate, and wherein the ball screw assembly defines a modular package/layout and accommodates additional design features. 16. The torque vectoring system of claim 14, further comprising: A controller operable to control the motor, the controller stored in memory and operable to execute an actuator control algorithm, reduces the likelihood of mechanical backlash and frictional hysteresis. 17. A torque vectoring system comprising: differential; a first drive shaft operatively coupled to the differential; a second drive shaft operatively coupled to the differential; A first gear train selectively driven by the differential and configured to selectively supply speed application from the differential to the first drive shaft and the second one of the drive shafts; a second gear train selectively driven by the differential and configured to selectively supply a speed reduction from the differential to the first drive shaft and the second one of the two drive shafts; a first clutch configured to selectively couple the first gear train to the first shaft during an acceleration request, the first clutch including a first clutch positioned in a first clutch basket Group; a second clutch configured to selectively couple the second gear train to the first shaft during a deceleration request, the second clutch including a second clutch positioned in a second clutch basket group; and an actuator configured to selectively close one of the first clutch or the second clutch, wherein the actuator is configured to (i) move the a lever arm to close the first clutch and (ii) move the lever arm in a second direction to close the second clutch, the lever arm being positioned between the first and second clutch sets so as to prevent The lever arm moves simultaneously in the first direction and the second direction. 18. The torque vectoring system of claim 17, further comprising (i) a countershaft drive gearset having a countershaft gear meshing with a countershaft mating gear, and (ii) from a driven gear set having a first driven gear and a second driven gear, wherein the countershaft mating gear and the first driven gear are mounted to rotate simultaneously with the gear shaft, and the second Two driven gears are fixed to rotate simultaneously with the other of the first drive shaft and the second drive shaft. 19. The torque vectoring system of claim 17, wherein the actuator comprises a ball screw assembly including a motor isolating the shaft in one of a first direction and a second direction . 20. The torque vectoring system of claim 17, further comprising: a first thrust plate configured to transfer force from the lever arm to the first clutch pack; and A second thrust plate configured to transfer force from the lever arm to the second clutch pack.