Abstract: A four wheel drive powertrain control for an automotive vehicle is disclosed. It includes a torque transfer case that distributes power from an engine-powered transfer case mainshaft to a secondary driving axle through a friction clutch as power is distributed directly from the engine-powered mainshaft to a primary driving axle. The friction clutch capacity is sufficient to mechanically lock the transfer case in a four wheel drive mode. If the clutch torque capacity is exceeded, a control algorithm will strategically ramp down engine torque requests by a powertrain controller to eliminate clutch slip.

Abstract: To provide a four-wheel drive system which improves running performance of an automotive vehicle by inhibiting a driving torque from becoming insufficient upon occurrence of a slip. An R slip sensing means of a DC motor torque calculating means senses a slip due to a spin of rear wheels. When the rear wheel slip is sensed, an R slip DC-motor-torque correcting means corrects a torque of the rear wheels so that a driving force of the rear wheels is reduced and then increased. The R slip DC-motor-torque correcting means reduces a driving torque of the rear wheels to eliminate the slip and holds the reduced driving torque until the slip is eliminated, and then increases the driving torque to a value lower than a value which the driving torque has taken at the time of occurrence of the slip. The driving torque is increased to a predetermined limit value depending on the number of slips.

Abstract: An electric drive unit for a vehicle includes an electric motor, two output shafts, a first speed reduction planetary gearset driven by the motor, a second speed reduction gearset driven by an output of the first gearset, and a compound planetary differential gearset including an input driveably connected to the output of the second gearset, a first differential output driveably connected to the first output shaft, and a second differential output driveably connected to the second output shaft.

Abstract: A differential limiting control apparatus for a vehicle has: clutch unit interposed between one rotational shaft and the other rotational shaft for variably transmitting a driving force between the one rotational shaft and the other rotational shaft; target differential speed setting unit for setting a target differential speed between the one rotational shaft and the other rotational shaft, actual differential speed detecting unit for detecting an actual differential speed between the one rotational shaft and the other rotational shaft, and clutch torque computing unit for computing an engagement force of the clutch unit by obtaining a deviation between the target differential speed and the actual differential speed, configuring a switching function by using at least a polarity related to an integral term of the deviation, and applying a sliding mode control.

Abstract: A drive force control method for a four-wheel drive vehicle having front wheels as main drive wheels always connected to a driving source, rear wheels as auxiliary drive wheels whose drive torque is adjustable, and a mechanism capable of adjusting a torque distribution ratio between the front wheels and the rear wheels so that the torque distribution ratio of the rear wheels to the front wheels is increased in turning and also capable of adjusting a torque distribution ratio between the right and left rear wheels in turning. The drive force control method includes the steps of detecting a vehicle speed, and gently decreasing the torque distribution ratio of a turning outer wheel to a turning inner wheel with an increase in the vehicle speed. When the transmission shift position is a low-speed position or a high-speed position or the vehicle is in reverse running, the torque distribution ratio of the turning outer wheel to the turning inner wheel is decreased.

Abstract: An all-terrain vehicle (ATV) has a subtransmission detachably fastened to an engine casing. The engine crankshaft includes a drive pulley connected via a belt to a driven pulley in the subtransmission, thus providing a continuously variable transmission (CVT) between the engine crankshaft and the subtransmission. The subtransmission includes a 2WD-4WD selector mechanism to select two-wheel-drive or four-wheel-drive and also includes a transmission selector mechanism to put the vehicle in park, neutral, reverse, high-speed drive or low-speed drive. By disposing these selector mechanisms in the subtransmission, mass centralization is improved relative to prior-art drivetrains wherein the 2WD-4WD selector mechanism connects to the front differential. When operating in 2WD mode, the drivetrain does not waste energy rotating the front drive shaft, as in the prior art.

Abstract: A control apparatus for a hybrid vehicle includes a required torque calculating portion that calculates required drive torque required of the vehicle; a running mode switching portion that switches between a motor running mode and a hybrid running mode according to the calculated required drive torque; a torque distribution control portion that sets the torque distribution between front and rear wheels according to the switched running mode; a gear noise preventing portion that prevents gear noise in a gear mechanism by changing the set torque distribution between the front and rear wheels when a predetermined gear noise producing condition is satisfied; and a drive torque control portion that calculates drive torques of the front and rear wheels based on the calculated required drive torque and the changed torque distribution and controls the torques of the engine and the electric motor.

Abstract: A powertrain for transmitting power to the drive wheels of a vehicle includes a transaxle case containing a transaxle drive mechanism for producing variable ratios of a speed of its output and a speed of its input, a differential mechanism for transmitting power between the output and the wheels of a first set of drive wheel, a transfer clutch secured to the output for transmitting power between the output and the wheels of a second set of drive wheels, and a control system for hydraulically actuating the transfer clutch.

Abstract: To provide a drive switching mechanism for a vehicle which allows the number of parts to be reduced by simplifying the structure for 2WD/4WD switching and differential lock switching. In a drive switching mechanism for a vehicle which enables 2WD/4WD switching and differential lock switching to be effected by a single operating lever, a flange is supported on the body side so as to be pivotable in one direction, the operating lever is coupled to the flange and the flange is pivoted in the one direction, and the operating lever is supported so as to be pivotable in the other direction different from the one direction, the operating lever being operated in the one direction or the other direction to enable the 2WD/4WD switching and the differential lock switching.

Abstract: Apparatus for installation in new motor vehicles or for retrofitting into existing motor vehicles, including an electric motor coupled to a drive shaft and a controller for the motor. The existing vehicle battery and/or an auxiliary storage battery can be used to power the motor to drive the vehicle during certain driving conditions, resulting in greatly increased fuel economy, without interfering with the normal performance of the vehicle. A kit of parts may be provided for simple and economical installation on existing vehicles. A motor vehicle so equipped.

Abstract: An HST propel system includes first and second pumps having displacements variable in response to movement of first (31) and second (33) control shafts, respectively; and a linkage arrangement for moving the control shafts in unison in response to movement of an operator input (37). The linkage arrangement comprises a crank arm (35) rotatable about its axis in response to movement of the input device, first (41) and second (51) input arms fixed relative to the crank arm, and first (45) and second (55) elongated control rods pivotally connected to the input arms. The system includes a swivel connector (43) cooperating with its input arm to define a swivel axis (S.A.1), fixed relative to the axis of the crank arm, and a swivel connector (53) cooperating with its input arm to define a swivel axis (S.A.2), moveable relative to the axis of the crank arm for straight tracking adjustment.

Abstract: A transfer case for use in a motor vehicle to selectively transfer drive torque from a powertrain to first and second pairs of wheels. The transfer case includes an input shaft driven by the powertrain and an output shaft selectively driven by the input shaft. A transfer mechanism is operably disposed between the input shaft and the output shaft to transfer drive torque from the input shaft to the output shaft. The transfer mechanism includes a first chain that is selectively driven by the input shaft and a second chain that is driven by the first chain and that transfers drive torque to the output shaft.

Abstract: A battery load power detecting system includes a generator current sensor which detects a current supplied from a generator to at least one of a battery and a load group including a steering device, and first and second load current sensors which detect a current supplied from at least one of the generator and the battery to the load group. A battery state monitor calculates a load power of the battery by multiplying a difference between both the currents by a voltage at a terminal of the battery detected by a voltage sensor. Therefore, the load state of the battery can be appropriately confirmed to avoid a situation where the steering device, e.g., a steering-by-wire type steering device, falls into an inoperable state due to power deficiency.

Abstract: This invention relates to multiple driven axle vehicles, and particularly to all-terrain vehicles equipped for rear wheel drive, four wheel drive, and on-demand front wheel drive. The invention is directed toward a system of switchable traction options allowing the vehicle operator to easily choose between different modes, such as rear wheel drive with an open or unlocked differential, rear wheel drive with a locked differential, four wheel drive with open differentials, four wheel drive with one locked differential, four wheel drive with two locked differentials, or rear wheel drive with on-demand four wheel drive.

Abstract: In the case of a control device for an at least partially four-wheel-driven motor vehicle, having a control unit which can variably distribute the driving torque of a drive unit to primary driving wheels, which are permanently connected with the drive unit, and to secondary driving wheels which, if required, can be connected by way of a transfer clutch with the drive unit, in that the control unit determines a desired clutch torque which is to be set by means of an actuator device at the transfer clutch, the control unit receives at least one input signal for detecting an accelerator pedal position and is further developed such that, when the desired clutch torque is determined, a basic pilot control fraction is taken into account, which is defined as a function of the accelerator pedal position and is corrected as a function of additional parameters which are detected or determined by the control unit.

Abstract: In the case of a control system for a vehicle with at least part-time four-wheel drive, having a control unit which detects or determines quantities proportional to the wheel speeds of all wheels and the vehicle speed, and by means of which the driving torque of a drive unit can be variably distributed to primary driving wheels, which are permanently connected with the drive unit, and to secondary driving wheels which, if required, can be connected with the drive unit, for the distribution of the driving torque, a clutch torque of a transfer clutch arranged between the drive unit and the secondary driving wheels is set by means of the control unit, and the control unit is further developed such that the clutch torque is increased if a difference is detected between the wheel speed of a wheel and the vehicle speed and/or if a difference is detected between the two wheels speeds of the wheels of at least one vehicle side.

Abstract: In the case of a control device for an at least partially four-wheel-driven motor vehicle, having a control unit which can variably distribute the driving torque of a drive unit to primary driving wheels, which are permanently connected with the drive unit, and to secondary driving wheels, which, if required, can be connected by way of a transfer clutch with the drive unit, wherein the control unit determines a desired clutch torque which is to be set by an actuator device at the transfer clutch. The control unit is further configured such that, when the desired clutch torque is determined, at least one degree of stress to the transfer clutch and/or at least one degree of stress to the actuator device are taken into account. In this case, the taking into account of a short-duration degree of stress to the transfer clutch is particularly important with a view to a closing which is as fast as possible for preventing a slip.

Abstract: A four-wheel drive work vehicle includes an engine, a pair of right and left steerable wheels rotatably driven by receiving power from the engine via a differential mechanism, a pair of right and left non-steerable wheels rotatably driven by receiving power from the engine via right and left side clutches and a pivotal cam mechanism for operating a clutch operating member for controlling the side clutch based on a steered displacement of the steerable wheels. The pivotal cam mechanism includes a cam member which is displaced based on the steered displacement and a cam follower member operably associated with the cam member.

Abstract: A full-time power take-off unit is equipped with a dual-mode bi-directional overrunning clutch and a shift mechanism to establish all-wheel drive and part-time four-wheel drive modes. Further, the power take-off unit includes a disconnect clutch that is controlled by the mode shift mechanism to establish a full-time four-wheel drive mode.

Abstract: A method of controlling a shiftable clutch in a drive train between a front axle and a rear axle of a motor vehicle with a four-wheel drive is provided. One axle is driven directly and the other axle, as a hang-on system, is coupled by way of the clutch. In order to create a method of controlling the shiftable clutch in a drive train between the front axle and the rear axle, and a corresponding system with an improved availability of the full four-wheel drive characteristic with a corresponding protection of the driving dynamics of the overall vehicle, the clutch is continuously acted upon by torque in an adjustable manner by way of a pilot control measure.

Abstract: A method and apparatus for a four-wheel drive motor vehicle provides improved cornering by disengaging drive torque to the inside rear wheel during significant steering maneuvers. The apparatus includes a primary front wheel drive motor vehicle driveline having a center differential which provides drive energy to the primary (front) driveline and secondary (rear) driveline and a rear axle assembly having a pair of normally engaged (active) clutches which provide drive energy to the respective rear wheels. A steering angle sensor detects angular displacement of the steering column or front (steering) wheels and an associated controller disengages the clutch associated with the rear wheel on the inside of the turn as determined by the steering angle sensor.

Abstract: A brake light warning system for safety helmets includes a transmitter module adapted for mounting to a vehicle, such as a motorcycle, and a receiver module adapted for mounting to a safety helmet. The transmitter module is configured to continuously transmit a transmission signal when a brake of the vehicle is disengaged and discontinue transmission of the transmission signal when a brake of the vehicle is engaged. The receiver module is configured to detect a presence or absence of the transmission signal from the transmitter module. The receiver module has at least one light generating element that illuminates or increases in brightness upon detection of the absence of the transmission signal to indicate that the vehicle brake is engaged.

Abstract: The present invention provides a shift mechanism disposed in a housing for providing operable communication between a shift actuator and a shift sleeve. The shift mechanism generally includes a shift rail, a shift fork, a first biasing member, and a second biasing member. The shift rail is slidably supported by the housing. The shift fork is slidably disposed on the shift rail and engages the shift sleeve. The first biasing member is disposed between the shift actuator and the shift rail for selectively biasing the shift rail in a first direction upon actuation of the shift actuator. The second biasing member is disposed between the housing and the shift fork for biasing the shift fork in a second direction that is substantially opposite the first direction.

Abstract: An axle disconnect system is provided whereby axles of a tandem or multi-axle vehicle may be easily and quickly engaged and disengaged as required and whereby the ring gear and differential gears remain stationary when the axle is disengaged. In multi-axle vehicles, a dual disconnect mechanism is contained in the front and auxiliary rear axles. When only the primary rear axle is necessary to propel the vehicle (e.g., during highway use) the transfer case interrupts torque to the front axle. Similarly, a clutch also interrupts torque transmission to the auxiliary rear axle. In this mode, the dual disconnect mechanism prevents the axle output shafts from back-driving the differential, thereby reducing parasitic losses and wear.

Abstract: A drive train assembly for use in powered vehicles or trailers having at least one axle of driving wheels. The assembly includes a coupling mechanism coupling the engine of the vehicle and the driving wheels. The coupling mechanism is activatable between a first and a second state, wherein in the first state the engine and driving wheels are mechanically uncoupled and in the second state the engine is mechanically coupled to the driving wheels. When the driving wheels are rotated by the vehicle or trailer being towed and the engine turned off the coupling mechanism ensures that no parts of the drive train assembly do not rotate and are therefore damaged due to lack of lubrication. Two embodiments are disclosed, one with the coupling (138) in the transfer box (110), and in the second embodiment the coupling is in the wheel hub assembly. Also disclosed is an oil pump assembly driven by the wheels rather than the drive train to provide some lubrication when the wheels are rotating and the engine is off.

Abstract: A vehicle powertrain incorporates a planetary gearset which is coupled with a front wheel drive mechanism and a rear wheel drive mechanism. The planetary gearset is controlled by two torque-transmitting mechanisms to establish an input member of the planetary gearset as well as a grounded member for the planetary gearset in combinations that will provide a two-wheel low drive ratio, a two-wheel high drive ratio, a four-wheel low drive ratio, and a four-wheel high drive ratio.

Abstract: An interlock mechanism is provided for a wheel end disconnect device. The interlock mechanism is activated by negative pressure for engaging and disengaging a wheel hub from an axle shaft. Vacuum pressure is routed through a wheel bearing for activating the interlock mechanism.

Abstract: A CPU computes a throttle opening degree increasing speed V?h and a steering wheel angular velocity V? based on a throttle opening degree ?h and a steering wheel angle ?. Based on the throttle increasing speed V?h and the steering wheel angular velocity V?, the CPU selects one of a first drive mode and a second drive mode. The CPU controls the power transmission ratio of a power transmitting device according to the selected drive mode. Therefore, the power transmission ratio of the power transmitting device is properly controlled in accordance with the degree of intention for acceleration of the driver, which is computed based on the throttle increasing speed V?h, and the turning speed of the steering wheel, which is computed based on the steering wheel angular velocity V?. Therefore, the drive mode is properly switched in accordance with the driving state of a four-wheel drive vehicle.

Abstract: A transfer case (1) with controllable clutch (5) for a motor vehicle, especially for a motor vehicle with part-time four-wheel drive, for distributing a driving torque coming in via a drive shaft (2) to at least two output shafts (3, 4). Hereby the output shaft (4) can be connected to the drive shaft (2) via the clutch (5), and the clutch (5) can be actuated via an electric motor (9) and a drive converter device (10) that is arranged between the electric motor (9) and the clutch (5) for converting a rotatory motion of the electric motor (9) into a translatory actuating motion for the clutch (5). The electric motor (9) is hereby designed as an induction motor.

Abstract: A parallel manual transmission for a four-wheel drive is provided and includes two input shafts, each of which can be non-rotatably coupled via its own clutch to a shaft that is powered by a drive engine.

Abstract: Providing a drive transmission apparatus for vehicle capable of ensuring the adaptability of an electric motor to a high-temperature environment and increasing the degree of freedom for apparatus layout. The drive transmission apparatus for vehicle serves to distribute a drive force generated by a rotary drive source 2 between drive wheels 6, 12, and includes: an input member 7 applied with the drive force from the rotary drive source 2; an output member 9 for outputting the drive force to the drive wheels 12; a hydraulic clutch 21 for hydraulically performing drive transmission/transmission cut-off between the input member 7 and the output member 9; an oil pump 31 for applying a hydraulic pressure to the hydraulic clutch 21; and a sensorless brushless motor for driving the oil pump.

Abstract: A distributor gear (1) with an adjustable coupling device (5) for a vehicle, in particular for a vehicle with a shiftable all-wheel drive is described for the distribution of an incoming drive torque via a drive shaft (2) to at least two output shafts (3, 4). It is moreover provided that an output shaft (4) can be connected via the coupling device (5) with the drive shaft (2) and that the coupling device (5) can be actuated via an electric motor (9) and a drive converter device (10) located between the electric motor (9) and the coupling device (5) for the conversion of rotary movement of the electric motor (9) into a translatory actuation movement for the coupling device (5). The electric motor (9) is incorporated into a gear (7).

Abstract: This invention relates to multiple driven axle vehicles, and particularly to all-terrain vehicles equipped for rear wheel drive, four wheel drive, and on-demand front wheel drive. The invention is directed toward a system of switchable traction options allowing the vehicle operator to easily choose between different modes, such as rear wheel drive with an open or unlocked differential, rear wheel drive with a locked differential, four wheel drive with open differentials, four wheel drive with one locked differential, four wheel drive with two locked differentials, or rear wheel drive with on-demand four wheel drive.

Abstract: An on-demand two-speed transfer case is equipped with a planetary gearset assembly and a range shift mechanism to provide high-range and low-range drive connections. The transfer case is also equipped with a dual-mode bi-directional overrunning clutch and a mode shift mechanism to establish on-demand and part-time four-wheel drive modes. Further, the transfer case includes a disconnect clutch and a disconnect shift mechanism to establish a two-wheel drive mode in addition to the four-wheel drive modes.

Abstract: A torque transfer mechanism is provided for controlling the magnitude of a clutch engagement force exerted on a multi-plate clutch assembly that is operably disposed between a first rotary and a second rotary member. The torque transfer mechanism includes a clutch actuator for generating and applying a clutch engagement force on the clutch assembly.

Abstract: To provide a vehicular two-wheel drive and four-wheel drive switching system the power consumption of which can be reduced. A vehicular two-wheel drive and four-wheel drive switching system is provided with a switching unit for transmitting power or disconnecting the transmission of power. The switching unit is provided with a driving shaft connected to the drive side, a driven shaft fitted to the driving shaft via an annular clearance gap. A plurality of connecting/disconnecting members are provided in a clearance between the driving shaft and the driven shaft for connecting or disconnecting the driving shaft and the driven shaft by being fitted or disconnected to/from respective opposite surfaces. A switching mechanism is provided for selectively positioning the connecting/disconnecting members in a position in which the driving shaft and the driven shaft are connected and in a position in which the driving shaft and driven shaft are disconnected.

Abstract: A transfer case for motor vehicles with off-the-road gear comprises a casing, an input shaft, a first output shaft, coaxial with the latter, a second output shaft, offset therefrom, a speed-reduction unit, a coupling unit and an offset drive. The speed-reduction unit comprises a central drive gearwheel, connected in a rotationally fixed manner to the input shaft, a central driven gearwheel and at least two intermediate transmissions, rotatable about spindles fixed to the casing, each with two intermediate gearwheels, one of which meshes with the central drive gearwheel and the other meshes with the central driven gearwheel, a first driven shaft, connected in a rotationally fixed manner to the central drive gearwheel, and a hollow second driven shaft, connected in a rotationally fixed manner to the central driven gearwheel, which driven shafts lead to a coupling unit.

Abstract: A differential gear mechanism includes a rotatable case driven by torque from an engine, a differential gear set housed in the case for differential distribution of the torque to a pair of output axes, comprising a first clutch, an annular plunger movable in a direction of the rotation axis and an annular electromagnetic actuator for actuation of the plunger in the direction of the rotation axis. The case further comprises a second clutch being slidable in the direction of the rotation axis and the second clutch is actuated by the plunger so as to be engaged with the first clutch.

Abstract: A drivetrain for a vehicle includes front and rear axles and a transfer case including two planetary gear sets and four clutches. The first member of the first planetary gear set is continuously connected with the first member of the second planetary gear set and the rear axle. The third member of the first planetary gear set is continuously connected to the second member of the second planetary gear set and the front axle through a transfer chain. An input is selectively connectable with the first member of the first planetary gear set through a first clutch, connectable with the second member of the first planetary gear set through a second clutch, and connectable with the third member of the first planetary gear set through a third clutch. A fourth clutch selectively connects the third member of the second planetary gear set with ground.

Abstract: An electromagnetic clutch for motor vehicle drive line applications includes a friction clutch pack, a ball ramp actuator and an electromagnetic coil. The ball ramp actuator includes a pair of circular members having opposed pairs of arcuate recesses receiving load transferring members and a torsion spring which provides a restoring force to return the circular members to their center, disengaged positions. Improved clutch control, particularly during disengagment, is achieved by this ball ramp actuator configuration.

Abstract: A four-wheel-drive vehicle includes: a body frame; a swing unit including a power unit, and a rear axle connected to the power unit so as to be driven by the power unit, the swing unit being supported on the body frame for vertical swing motion; a front reduction gear for transmitting power to front wheels; and a front propeller shaft connecting the power unit to the front reduction gear for power transmission.

Abstract: A transfer case is provided for a vehicle having front and rear axles. The transfer case includes a planetary gear set with first, second and third members. The first member is continuously connected with the front axle and the second member is continuously connected with the rear axle. An input shaft is selectively connectable with the first, second or third member. The transfer case provides rear-wheel drive when the second member is connected with the input shaft, all-wheel drive when the third member is connected with the input shaft, and front-wheel drive when the first member is connected with the input shaft. It is important that the specific members of the planetary gear set be chosen so the absolute value of the torque of the third member is equal to the sum of the absolute value of the torques of the first and second members.

Abstract: In a power switching apparatus which switches a power transmitting state from a drive member to left and right two driven members, a circumferential connection surface of the drive member and each of circumferential connection surfaces in both of the driven members are wedge connected according to an interposition of rolling elements by bringing end surfaces of cages which are moved in an axial direction due to an electromagnetic force into frictional contact with the driven members and so as to rotate together therewith, in a state in which a switching means is set in an on mode.

Abstract: A power transfer system is provided and equipped with a torque transfer coupling which includes a clutch and a ball-screw actuator. The ball-screw actuator functions to axially translate an apply plate via a closed hydraulic system to operatively engage the clutch and vary the frictional engagement thereof.

Abstract: A torque-biasing system (10) includes a torque-biasing device (12) and a control unit (14) for use in a motor vehicle. The torque-biasing system is preferably installed in a vehicle having a first front wheel (18) with a first rotational speed and second wheel (20) with a rear rotational speed and an engine (22) with a torque output. The control unit (14) functions to determined when and how to bias the torque output of the front and rear wheels, and to control the torque-biasing device (12) based on this determination.

Abstract: A torque variation control device for a vehicle which has a motor providing rotational torque to a drive shaft of a vehicle, a motor control means controlling the motor based on drive torque, and a rotational velocity detection means detecting a rotational velocity of the drive shaft or a rotational shaft of the motor. The device has a feature that the device includes a torque variation detection means detecting a torque variation of the vehicle caused by a variation of the rotational velocity, and a compensation torque setting means setting compensation torque in an opposite phase relative to the torque variation.

Abstract: The present invention provides a transmission mechanism with a single differential mechanism for an automotive vehicle. The transmission mechanism of the invention is of a compact structure and a relatively less cost of manufacturing, and makes a clearance between the chassis of the automotive vehicle and the ground increased. The performance of the automotive vehicle equipped with the transmission mechanism of the invention can be improved.

Abstract: A power-split transmission for motor vehicles with off-road travel consists of a case (1), of an input shaft (2), of a first output shaft (3) coaxial with the latter, of a second output shaft (4), of a reduction unit (5), of a clutch unit (6) and of an offset drive (7).

Abstract: A four-wheel drive vehicle has front wheels and rear wheels driven by an engine, and a coupling for changing the distribution ratio of torque to the front wheels and the rear wheels. An ECU determines whether engine braking is being applied based on the vehicle speed V and the throttle opening degree Od. When determining that engine braking is being applied, the ECU temporarily performs the engine braking related control. The ECU controls the engaging force of the coupling such that the distribution ratio of torque to the front wheels and the rear wheels is changed to a more equalized state in the engine braking related control than that before the engine braking related control is started. Accordingly, the fixing force of the front wheels and the rear wheels is temporarily increased without delay when engine braking is applied.

Abstract: A vehicle drive system includes a compact drive mode-shifting mechanism that is mounted in the final drive gearset of a vehicle. The drive mode-shifting mechanism includes a first shaft, a second shaft, and a clutch assembly. The first shaft forms an input shaft for the differential for a pair of wheels, the second shaft transmits engine power and the clutch assembly connects and disconnects the first and second shafts to one another to effect either the two-wheel-drive mode or the four-wheel-drive mode. The first shaft has an outer surface provided with a first spline, the second shaft has an outer surface provided with a second spline, and said clutch assembly includes an axially movable shifting member provided with an internal spline.