JP6476225B2 - Torque distribution control device for four-wheel drive vehicle - Google Patents

Description

  The present invention provides a four-wheel drive vehicle in which one of a front wheel and a rear wheel is a first drive wheel (main drive wheel) and the other is a second drive wheel (sub drive wheel). Front-rear torque distribution device for distributing drive torque transmitted to the wheels, left-right torque distribution device for distributing drive torque transmitted to the second left secondary drive wheel and the right second drive wheel, and these The present invention relates to a torque distribution control device for a four-wheel drive vehicle comprising control means for controlling drive torque distributed by a front / rear torque distribution device and a left / right torque distribution device.

  Conventionally, for example, a vehicle as shown in Patent Document 1 is a four-wheel drive vehicle having a front wheel as a main drive wheel and a rear wheel as an auxiliary drive wheel, and further distributes drive force to the left and right rear wheels. As a device, an electromagnetic torque distribution clutch is provided on each of the driving force transmission paths connected to the left and right rear wheels. By changing the fastening force of the torque distribution clutch, the ratio of torque distributed between the left and right rear wheels can be arbitrarily controlled.

  In such a vehicle, in addition to steering of the steered wheels, the yaw moment of the vehicle is controlled using a difference in driving force between the left and right rear wheels by controlling an electromagnetic clutch. That is, the estimated drive torque output from the transmission is calculated based on the engine speed, intake negative pressure (or intake flow rate), and the like. Based on the calculated estimated driving torque and the lateral acceleration, steering angle, and wheel speed of the vehicle, torque to be distributed to the left and right rear wheels is calculated. For example, if the vehicle slip angle is greater than or equal to a predetermined value, it is determined that the vehicle behavior is unstable, the rear differential gear is controlled to reduce the torque distributed to the left and right rear wheels, and The torque distributed to the turning outer wheel of the rear wheels is reduced. As a result, the vehicle behavior is stabilized.

JP 2011-077942 A

  By the way, when controlling the torque distributed to the left and right auxiliary drive wheels (rear wheels) as described above, a difference (left / right difference) occurs in the command value of the torque distributed to the left and right auxiliary drive wheels. There is a case where the torque (front-rear distribution amount) distributed to the auxiliary driving wheel between the driving wheel (front wheel) and the auxiliary driving wheel (rear wheel) exceeds the command value. In such a case, in order to prevent the behavior of the vehicle from becoming unstable and improve the running performance, the left / right difference (the left / right distribution amount) is made to follow the command value based on the running state of the vehicle. It is desirable to determine whether to give priority to this, or to give priority to making the front-back difference (front-rear distribution amount) follow the command value.

  The present invention has been made in view of the above-described problems, and its purpose is to make the front wheels the first drive wheels (main drive wheels) and the rear wheels the second drive wheels (sub drive wheels), and To enable more optimal torque distribution control when performing front-rear and left-right drive torque distribution control in a four-wheel drive vehicle equipped with a driving force distribution device for distributing driving force to wheels. Thus, an object of the present invention is to provide a vehicle torque distribution control device that can effectively prevent the behavior of the vehicle from becoming unstable and improve the running performance.

In order to achieve the above object, a torque distribution control device for a vehicle according to the present invention uses either a front wheel (WFL, WFR) or a rear wheel (WRL, WRR) as a first drive wheel (a main wheel in an embodiment described later). In a four-wheel drive vehicle in which the other drive wheel is the second drive wheel (sub drive wheel in the embodiment described later), the first drive as the front-rear distributed drive torque for each of the first drive wheel and the second drive wheel. A front-rear torque distribution device (14) for distributing and transmitting wheel torque and second drive wheel torque, and a left second drive wheel on the left side of the second drive wheel and a right second drive wheel on the right side The left and right torque distribution device (16) for distributing and transmitting the left drive torque and the right drive torque as the left and right distribution drive torque to each, the first drive wheel torque and the second drive wheel distributed by the front and rear torque distribution device Torque and left and right torque And a control means (Ua) for controlling the left drive torque and the right drive torque distributed by the distribution apparatus, wherein the control means (Ua) includes a command value for the left drive torque and a right drive torque. When the second driving wheel torque, which is the sum of the left driving torque and the right driving torque, exceeds the command value of the second driving wheel torque, the difference from the command value of Left-right difference priority control that prioritizes making the difference between the left drive torque and the right drive torque follow the difference between the left drive torque command value and the right drive torque command value, and the left drive torque and the right drive torque. It is characterized in that either the left-right sum priority control that gives priority to following the sum of the command value of the left drive torque and the command value of the right drive torque is selected and performed.

  According to the torque distribution control device for a four-wheel drive vehicle according to the present invention, the difference between the command value (the command value of the left and right distribution drive torque) between the right drive torque and the left drive torque distributed to the left and right second drive wheels ( When the second drive torque distributed to the second drive wheel (front / rear distributed drive torque) exceeds the command value due to the change in the left / right difference), the left / right difference priority control and the left / right sum are controlled according to the running state of the vehicle. By selecting any one of the priority controls, the optimum torque distribution control can be performed when performing the front / rear and left / right torque distribution control. Therefore, it is possible to effectively prevent the behavior of the vehicle from becoming unstable and improve the running performance of the vehicle.

  Further, in this torque distribution control device, the left / right difference priority control is an amount by which one of the left drive torque command value and the right drive torque command value falls below the predetermined lower limit value when it falls below a predetermined lower limit value. Is added to the other of the left driving torque command value and the right driving torque command value, or one of the left driving torque command value and the right driving torque command value exceeds a predetermined upper limit value. In addition, the control may be such that the amount exceeding the upper limit value is subtracted from the other of the left drive torque command value and the right drive torque command value.

  Alternatively, in the case where one of the left drive torque command value and the right drive torque command value falls below a predetermined lower limit value, the left-right sum priority control is performed by setting the amount below the lower limit value to the left drive torque command value. When the control of subtracting from the other of the command value of the right drive torque and the command value of the right drive torque or one of the command value of the left drive torque and the command value of the right drive torque exceeds the predetermined upper limit value, the upper limit value is exceeded. Control may be made to add the amount to the other of the command value for the left drive torque and the command value for the right drive torque.

  According to these configurations, when one of the command value for the left drive torque and the command value for the right drive torque exceeds a predetermined limit value, the amount exceeding the limit value is set to the left drive torque. Control is performed to increase or decrease the other of the command value of the right drive torque and the command value of the right drive torque, so that one of the command value of the left drive torque and the command value of the right drive torque has a predetermined limit value. When the value exceeds the value, the difference (left-right difference) between the left driving torque and the right driving torque, or the difference (front-back difference) between the first driving torque and the second driving torque can be maintained. Therefore, more optimal torque distribution control can be performed.

  In this torque distribution control device, the longitudinal acceleration determination means for determining the longitudinal acceleration (GH) of the vehicle and the lateral acceleration determination for determining the lateral acceleration (GE) of the vehicle as means for determining the running state of the vehicle. The control means performs left-right difference priority control in a driving state where the longitudinal acceleration of the vehicle is relatively small and the lateral acceleration is relatively large, and the longitudinal acceleration of the vehicle is relatively large and the lateral acceleration is compared. In a small traveling state, left / right sum priority control may be performed.

  According to this configuration, when the second drive wheel torque distributed to the second drive wheel by the front and rear torque distribution device exceeds the command value, the shortage of the left / right distribution drive torque is distributed to the left and right opposite drive wheels. Left and right difference priority control that prioritizes left and right difference by adding to the amount, and right and left sum priority that prioritizes front and rear difference (front and rear distribution) by subtracting the insufficient amount of left and right distribution drive torque from the distribution amount to the opposite drive wheel The priority can be varied according to the driving condition (running state) of the vehicle as to which control is to be preferentially performed. Therefore, more optimal drive torque distribution control can be performed in accordance with the running conditions of the vehicle.

  In addition, the name and code | symbol in said parenthesis show the name and code | symbol of the corresponding component of embodiment mentioned later as an example of this invention.

  According to the torque distribution control device for a four-wheel drive vehicle according to the present invention, it is possible to perform more optimal torque distribution control when performing front / rear and left / right drive torque distribution control. It is possible to effectively prevent the vehicle from becoming unstable and improve the running performance.

It is a figure showing the driving force transmission system of vehicles concerning one embodiment of the present invention. It is an enlarged view of a speed increasing device and a rear differential gear. It is a block diagram which shows the structure of 4WD-ECU. It is a block diagram which shows the flow of the process in the torque distribution control of this embodiment. It is a block diagram which shows the flow of the process in the torque distribution control of this embodiment. It is a figure which shows the change of the command value of the torque distributed to the left and right rear wheels in torque distribution control. It is a figure which shows the change of the command value of the torque distributed to the left and right rear wheels in torque distribution control. It is a figure for demonstrating the setting value of adjustment gain. It is a figure which shows the example of a setting of an adjustment gain. It is a figure which shows the example of a setting of an adjustment gain.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a diagram illustrating a driving force transmission system for a vehicle according to an embodiment of the present invention. FIG. 2 is an enlarged view of the speed increasing device and the rear differential gear. As shown in FIG. 1, the vehicle according to the first embodiment to which the present invention is applied includes left and right front wheels WFL, WFR as main drive wheels (first drive wheels) and sub drive wheels (second drive wheels). Left and right rear wheels WRL and WRR, and the left and right front wheels WFL and WFR are basically always driven when the vehicle is running, and the left and right rear wheels WRL and WRR are in a driving state of the vehicle. It is driven accordingly.

  An automatic transmission T is connected to an engine E mounted horizontally at the front of the vehicle body. The automatic transmission T is connected to the left and right front wheels WFL and WFR via the front differential gear 11 and the left and right front drive shafts 12 and 12. Is done. The front differential gear 11 has left and right via a transfer (not shown), a front propeller shaft 13, a speed increasing device 14, a rear propeller shaft 15, a rear differential gear 16, and left and right rear drive shafts 17L and 17R. It is connected to the rear wheels WRL and WRR.

  As shown in FIG. 2, the speed increasing device 14 includes a planetary gear mechanism 21, a speed increasing clutch 22, and a direct coupling clutch 23.

  The planetary gear mechanism 21 is supported by the input sun gear 24 fixed to the rear end of the front propeller shaft 13, the output sun gear 25 fixed to the front end of the rear propeller shaft 15, the carrier 26, and the carrier 26. A plurality of double pinions 27. Each double pinion 27 is integrally provided with an input side pinion 27a and an output side pinion 27b, and the number of teeth of the output side pinion 27b is set to be larger than the number of teeth of the input side pinion 27a. The number of teeth of the sun gear 25 is set smaller than the number of teeth of the input-side sun gear 24.

  The hydraulic multi-plate type speed increasing clutch 22 is a clutch outer 29 fixed to a housing 28 and a clutch inner 30 positioned inside the clutch outer 29 via a plurality of friction engagement elements 31. When the plurality of friction engagement elements 31 are engaged by the supply of hydraulic pressure, the clutch inner 30 is fastened to the clutch outer 29 and is restrained to the housing 28 so as not to rotate.

  The hydraulic multi-plate direct coupling clutch 23 includes a clutch inner 30 integrated with the clutch inner 30 of the speed increasing clutch 22 and the carrier 26 of the planetary gear mechanism 21, a clutch inner 33 integrated with the front propeller shaft 13, and a clutch outer 32. And a plurality of friction engagement elements 34 disposed between the clutch inner 33 and a one-way clutch 35 disposed between the clutch outer 32 and the clutch inner 33. When the rotational speed of the clutch inner 33 exceeds the rotational speed of the clutch outer 32, the one-way clutch 35 slips and the transmission of the driving force is interrupted. When the plurality of friction engagement elements 34 are engaged by the supply of hydraulic pressure, the clutch outer 32 is fastened to the clutch inner 33 and the front propeller shaft 13 is integrated with the carrier 26 of the planetary gear mechanism 21.

  Therefore, when the speed increasing clutch 22 is engaged and the direct connection clutch 23 is released, the carrier 26 of the planetary gear mechanism 21 is restrained to be non-rotatable by the housing 28. Therefore, the input side sun gear 24, the output side sun gear 25, and the double pinion The rotation speed of the front propeller shaft 13 is increased at a speed increase ratio (for example, 1.05) determined by the number of teeth of 27 and output to the rear propeller shaft 15.

  Conversely, when the speed increasing clutch 22 is released and the direct clutch 23 is engaged, the input side sun gear 24 and the carrier 26 of the planetary gear mechanism 21 are integrated and locked, so that the rotation of the front propeller shaft 13 is prevented. It is output to the rear propeller shaft 15 as it is.

  Since the rear differential gear 16 has a substantially mirror-symmetrical structure with respect to the center plane of the vehicle body, the structure of the left portion of the center plane of the vehicle body will be described as a representative example. Note that symmetrical components are distinguished from each other by adding L and R symbols to the reference numerals in the drawings. Also in the following description, when it is necessary to distinguish between left and right, the reference numerals with L and R symbols are used.

  A driven bevel gear 37 fixed to the intermediate portion of the input shaft 36 disposed coaxially between the opposing ends of the left and right rear drive shafts 17L, 17R is a drive bevel gear 38 fixed to the rear end of the rear propeller shaft 15. To mesh. A planetary gear mechanism 39L and an electromagnetic multi-plate torque distribution clutch 40L are disposed between the input shaft 36 and the left rear drive shaft 17L.

  The planetary gear mechanism 39 includes a ring gear 41, a carrier 42, a sun gear 43, and a plurality of pinions 44 supported by the carrier 42 and simultaneously meshed with the ring gear 41 and the sun gear 43. The ring gear 41 includes the input shaft 36. The carrier 42 is coupled to the right end of the left rear drive shaft 17L.

  The torque distribution clutch 40 includes a clutch outer 46 fixed to the housing 45, a clutch inner 47 coupled to the sun gear 43 of the planetary gear mechanism 39, and a plurality of friction engagements disposed between the clutch outer 46 and the clutch inner 47. .. And an electromagnetic actuator 49 (see FIG. 1) for integrally coupling the clutch outer 46 and the clutch inner 47 by engaging the friction engagement elements 48 with each other.

  When the electromagnetic actuator 49 is OFF, the torque distribution clutch 40 is released and the sun gear 43 can freely rotate. Therefore, the driving force of the input shaft 36 is not transmitted to the left rear drive shaft 17L. On the other hand, in a state where the electromagnetic actuator 49 is turned on and the torque distribution clutch 40 is engaged, the sun gear 43 is unrotatably restrained by the housing 45, so that the driving force of the input shaft 36 is transmitted to the left rear drive shaft 17L. .

  At this time, the torque transmitted from the input shaft 36 to the left rear drive shaft 17L can be continuously changed by changing the current supplied to the electromagnetic actuator 49 to change the slip amount of the torque distribution clutch 40. it can.

  Therefore, by changing the fastening force of the left and right torque distribution clutches 40L, 40R of the rear differential gear 16, the ratio of the torque distributed between the front wheels WFL, WFR and the rear wheels WRL, WRR is arbitrarily controlled, and the left and right The ratio of torque distributed between the rear wheels WRL, WRR can be arbitrarily controlled.

  Next, the configuration of the 4WD electronic control unit (4WD-ECU) Ua that controls the operation of the speed increasing device 14 and the rear differential gear 16 will be described with reference to FIG.

  The input unit 51 of the 4WD electronic control unit Ua includes a FI / AT electronic control unit Ub that controls the operation of the engine E and the automatic transmission T, and an ESC electronic control unit Uc that controls the operation of the vehicle behavior stabilization system. For example, a vehicle speed sensor 52a for detecting the vehicle speed from the rotation speed of the gear of the automatic transmission T and a steering angle sensor 52b for detecting the steering angle of the steering wheel are connected.

  The signal input to the input unit 51 from the FI / AT electronic control unit Ub includes the engine speed, the intake negative pressure, the main shaft and counter shaft speeds of the automatic transmission T, the shift position of the automatic transmission T, and the like. . The signals input from the ESC electronic control unit Uc to the input unit 51 include wheel speeds of the front wheels WFL, WFR and rear wheels WRL, WRR, vehicle lateral acceleration, vehicle longitudinal acceleration, and the like.

  The estimated drive torque calculation unit 53 includes an engine speed input from the input unit 51, a negative intake pressure (or intake flow rate), a gear ratio estimated from the rotation speeds of the main shaft and the counter shaft, a speed ratio of the torque converter, The estimated driving torque output from the transmission T is calculated based on the efficiency at the gear stage. Instead of estimating the gear ratio from the rotation speeds of the main shaft and the counter shaft, the gear ratio of the shift position detected by the shift position sensor may be used.

  The steering control unit 54 distributes the left and right rear wheels WRL and WRR based on the estimated driving torque calculated by the estimated driving torque calculating unit 53 and the lateral acceleration, steering angle and wheel speed input from the input unit 51. The steering control torque to be calculated is calculated. For example, when the slip angle of the vehicle is greater than or equal to a predetermined value, it is determined that the vehicle behavior is in an unstable state, and the torque distributed to the left and right rear wheels WRL and WRR is reduced by controlling the rear differential gear 16. In addition, the vehicle behavior is stabilized by reducing the torque distributed to the turning outer wheel of the left and right rear wheels WRL, WRR.

  The speed increase control unit 55 engages the speed increasing clutch 22 of the speed increasing device 14 when the vehicle body speed is medium speed and the lateral acceleration is large, and the rotational speed of the rear propeller shaft 15 with respect to the rotational speed of the front propeller shaft 13. And the rear differential gear 16 distributes torque to the turning outer wheels of the left and right rear wheels WRL and WRR, thereby improving turning performance while avoiding understeering of the vehicle. When the vehicle body speed is low or high and the lateral acceleration is small, the direct clutch 23 of the speed increasing device 14 is engaged and the speed increase of the rear propeller shaft 15 with respect to the speed of the front propeller shaft 13 is stopped. Thus, by distributing the torque to the turning outer wheel of the left and right rear wheels WRL, WRR by the rear differential gear 16, stable turning performance is ensured.

  Further, if the speed increase is executed, the vehicle behavior may be disturbed, and the operation of the speed increase device 14 is prohibited when the operation control unit 54 outputs a speed increase prohibition request.

  The LSD control unit 56 compares the wheel speeds of the left and right front wheels WFL and WFR with the wheel speeds of the left and right rear wheels WRL and WRR, and the friction coefficient of the road surface that the front wheels WFL and WFR step on when the vehicle starts is determined by the rear wheel WRL. When the front wheels WFL and WFR slip because they are smaller than the friction coefficient of the road surface on which the WRR steps, or even if the friction coefficient of the road surface on which the four wheels step is equal, the main driving force of the front wheels WFL and WFR is the rear wheel WRL. When the front wheel WFL, WFR slips because it is larger than the auxiliary driving force of WRR, the LSD torque distributed to the rear wheels WRL, WRR is calculated according to the differential rotation between the front and rear wheels. When the LSD torque is distributed to the rear wheels WRL and WRR by the rear differential gear 16, the slippage of the front wheels WFL and WFR is eliminated accordingly, and the vehicle can start smoothly.

  The uphill controller 58 compares the actual longitudinal acceleration detected by the longitudinal acceleration sensor with the estimated longitudinal acceleration obtained by differentiating the vehicle speed, thereby calculating the vehicle uphill angle (inclination angle of the road uphill). Then, in order to increase the climbing force at the start of the vehicle on the uphill, the uphill starting torque distributed to the rear wheels WRL, WRR is calculated by the rear differential gear 16 according to the uphill angle.

  The torque adding unit 57 adds the steering control torque calculated by the steering control unit 54, the LSD torque calculated by the LSD control unit 56, and the uphill starting torque calculated by the uphill control unit 58.

  The clutch torque limiting unit 60 prevents the rear differential gear 16 from being applied to the rear wheels WRL and WRR in order to prevent an excessive load from acting on the rear differential gear 16 when the vehicle is reverse-backed and forward-backed. Limit the upper limit of the target torque to be transmitted.

  The current control unit 61 converts the clutch torque command value calculated by the clutch torque limiting unit 60 into a current value (PWM value) supplied to the electromagnetic actuators 49L and 49R of the torque distribution clutches 40L and 40R of the rear differential gear 16.

  Thus, the drive circuit unit 62 controls the operation of the speed increasing device 14 based on the speed increasing command output from the speed increasing control unit 55, and the rear differential gear 16 based on the current value output from the current control unit 61. Control the operation of

  Here, drive torque distribution control for the left rear wheel WRL and the right rear wheel WRR when the vehicle turns will be described. During the turning of the vehicle, the magnitude of the torque of the left and right rear wheels WRL, WRR is usually the sum of the left rear wheel torque and the right rear wheel torque (hereinafter sometimes referred to as a first relationship). Control is performed based on the torque request in the front-rear direction and the difference between the left rear wheel torque and the right rear wheel torque (hereinafter also referred to as a second relationship), that is, the torque request in the turning direction.

  The torque distribution control in this case will be described using mathematical expressions. The target torque of the left rear wheel WRL is TT1, the target torque of the right rear wheel WRR is TT2, the total target torque of the left and right rear wheels WRL and WRR (the sum of the left rear wheel torque and the right rear wheel torque) is TRT, and the left and right rear wheels When the target torque difference between WRL and WRR (the difference between the left rear wheel torque and the right rear wheel torque) is ΔTT, the following equation (1) is established from the first relationship, and the following equation (2) is established from the second relationship.

TT1 + TT2 = TRT (1)
TT1-TT2 = ΔTT (2)

ΔTT is expressed by the following equation (3) where YMT is the target yam moment (clockwise is positive), Y is the wheel radius, r is the red width (distance between the left and right rear wheels WRL, WRR) Tr.
ΔTT = 2 · r · YMT / Tr (3)

  Therefore, the target torques TT1 and TT2 for the left and right rear wheels WRL and WRR are uniquely determined from the above equations (1) and (2).

  Thus, the torque requirement in the front-rear direction and the torque requirement in the turning direction can be satisfied from the first relationship and the second relationship, and the running performance of the vehicle is emphasized.

  4 and 5 are block diagrams for explaining the flow of processing in the torque distribution control of the present embodiment. In this torque distribution control, the requested left and right sum torque (rear wheel shaft torque) TM (71) and the requested left and right differential torque TS (72) are input, and the values restricted by the restriction blocks 81 and 82 (here, whichever Is also 0.5 times (1/2 times the value). Thereafter, a difference calculation block 83 calculates a difference value between the required left-right sum torque TM and the required left-right difference torque TS, and a sum calculation block 84 calculates a sum value of the requested left-right sum torque TM and the requested left-right difference torque TS. Calculated.

  Further, in the lower limit calculation block 91, the value of the required left-right sum torque (rear wheel shaft torque) TM restricted by the restriction block 81 and the lower limit value L1 of the required torque preset in the left and right rear wheels WRL, WRR (per wheel) The lower limit value is compared, and the lower of these values is output. That is, when the lower limit value L1 is smaller than the output value of the limit block 81, the lower limit value L1 is output as the output value of the lower limit value calculation block 91, and the output value of the limit block 81 is smaller than the lower limit value L1. In this case, the output value of the limit block 81 is output as the output value of the lower limit calculation block 91.

  Thereafter, in the first lower limit processing block 85, the difference value calculated in the previous difference calculation block 83 is compared with the output value of the lower limit calculation block 91, and the larger value is selected ( Lower limit processing) is performed. That is, when the difference value between the requested left-right sum torque TM and the requested left-right difference torque TS is larger than the output value of the lower limit calculation block 91, the difference value is selected, and the requested left-right sum torque TM and the requested left-right difference torque TS. When the difference value is equal to or smaller than the output value of the lower limit calculation block 91, the output value is selected. Thereafter, in the first deficient amount calculation block 87, the value of the difference between the required left / right sum torque TM and the required left / right difference torque TS calculated in the previous difference calculation block 83, and the value selected in the first lower limit processing block 85, The difference value is calculated.

  On the other hand, in the second lower limit processing block 86, the sum value calculated in the previous sum calculation block 84 is compared with the output value of the lower limit calculation block 91 to select the larger value (lower limit). Limit processing) is performed. That is, when the sum of the requested left-right sum torque TM and the requested left-right difference torque TS is greater than the output value of the lower limit calculation block 91, the sum value is selected, and the requested left-right sum torque TM and the requested left-right difference torque When the value of the sum of TS is less than or equal to the output value of the lower limit calculation block 91, the output value is selected. Thereafter, in the second deficient amount calculation block 88, the sum of the required left / right sum torque TM and the required left / right difference torque TS calculated in the previous sum calculation block 84, and the value selected in the second lower limit processing block 86, The difference is calculated.

  Further, the first adjustment gain multiplier 93 multiplies the value calculated by the first deficiency calculation block 87 by the value of the lower limit deficiency adjustment gain (hereinafter referred to as “lower adjustment gain”) Ga. The second adjustment gain multiplication unit 94 calculates a value obtained by multiplying the value calculated by the second shortage amount calculation block 88 by the value of the lower limit side adjustment gain Ga.

  Further, the requested right rear wheel torque calculation block 89 calculates the sum of the value selected by the first lower limit limit processing block 85 and the value calculated by the second adjustment gain multiplier 94. Further, in the requested left rear wheel torque calculation block 90, the sum of the value selected in the second lower limit processing block 86 and the value calculated in the first adjustment gain multiplier 93 is calculated. The (*) and (**) marks shown at the right end of FIG. 4 are connected to the (*) and (**) marks shown at the left end of FIG.

  Thereafter, as shown in FIG. 5, in the first upper limit processing block 101, the sum value calculated in the previous required right rear wheel torque calculation block 89 and the upper limit of the required torque set in advance in the left and right rear wheels WRL, WRR. A process of comparing the value L2 (upper limit value per wheel) and selecting the smaller value (upper limit process) is performed. That is, the sum value calculated by the requested right rear wheel torque calculation block 89 (the sum value of the value selected by the first lower limit processing block 85 and the value calculated by the second adjustment gain multiplier 94) is the upper limit. When the value is larger than the value L2, the upper limit value L2 is selected. When the sum calculated by the requested right rear wheel torque calculation block 89 is less than or equal to the upper limit value L2, the sum calculated by the requested right rear wheel torque calculation block 89 is selected. The value of is selected. Thereafter, the third shortage amount calculation block 103 calculates a difference value between the sum value calculated in the previous request right rear wheel torque calculation block 89 and the value selected in the first upper limit processing block 101. .

  On the other hand, in the second upper limit processing block 102, the sum value calculated by the previous request left rear wheel torque calculation block 90 and the preset upper limit value L2 of the request torque for the left and right rear wheels WRL, WRR (the upper limit per wheel). Value) and a process of selecting the smaller value (upper limit process) is performed. That is, the sum value calculated by the requested left rear wheel torque calculation block 90 (the sum value of the value selected by the second lower limit processing block 86 and the value calculated by the first adjustment gain multiplier 93) is the upper limit. When the value is larger than the value L2, the upper limit value L2 is selected. When the sum calculated by the requested left rear wheel torque calculation block 90 is less than or equal to the upper limit value L2, the sum calculated by the requested left rear wheel torque calculation block 90 is selected. The value of is selected. Thereafter, the fourth shortage amount calculation block 104 calculates a difference value between the sum value calculated in the previous request left rear wheel torque calculation block 90 and the value selected in the second upper limit processing block 102. .

  Further, the third adjustment gain multiplication unit 95 multiplies the value calculated by the third deficiency calculation block 103 by the value of the upper limit deficiency adjustment gain (hereinafter referred to as “upper limit adjustment gain”) Gb. The fourth adjustment gain multiplication unit 96 calculates a value obtained by multiplying the value calculated by the fourth deficiency calculation block 104 by the value of the upper limit side adjustment gain Gb.

  Further, in the requested right rear wheel torque calculation block 97, the requested right rear wheel torque 111, which is the sum of the value selected in the first first upper limit processing block 101 and the value calculated in the fourth adjustment gain multiplication unit 96. Is calculated. Further, in the requested left rear wheel torque calculation block 98, the requested left rear wheel torque 112, which is the sum of the value selected in the second upper limit processing block 102 and the value calculated in the third adjustment gain multiplier 95. Is calculated. The requested right rear wheel torque 111 and the requested left rear wheel torque 112 serve as command values (command torques) for driving torque distributed to the left and right rear wheels WRL and WRR in the torque distribution control of the present embodiment.

  FIG. 6 is a diagram (graph) illustrating an example of a change (change with respect to elapsed time t) of a command value (command torque) of torque distributed to the left and right rear wheels WRL, WRR in the torque distribution control of the present embodiment. It is a figure which shows the right-and-left difference priority control which gives priority to making the difference of the drive torque (left-right distribution drive torque) distributed to the wheel WRL and the right rear wheel WRR follow the command value. FIG. 6A shows a total value (requested) of drive torques distributed to the left and right rear wheels WRL and WRR with priority given to the difference (left-right difference) between the drive torques distributed to the left rear wheel WRL and the right rear wheel WRR. The left and right rear wheels WRL are given priority to the difference (left / right difference) between the driving torques distributed to the left rear wheel WRL and the right rear wheel WRR. , Control for reducing the total value of the drive torque distributed to WRR (required right and left sum torque TM). Moreover, (i) of each figure is a graph which shows the change of the request | requirement right-and-left sum torque TM and the request | requirement right-and-left difference torque TS which are the values of the sum and difference of the command torque allocated to each of the left rear wheel WRL and the right rear wheel WRR. (Ii) is a graph showing changes in the required right rear wheel torque TR and the required left rear wheel torque TL, which are command torques distributed to the left rear wheel WRL and the right rear wheel WRR, respectively.

  In the example shown in FIG. 6A, the lower limit side adjustment gain Ga described above is +1. Then, the difference between the drive torque TL distributed to the left rear wheel WRL generated at time t = 0 and the drive torque TR distributed to the right rear wheel WRR gradually changes (increases). The required left-right sum torque TM is a constant value (b0) until time t = ta1, and the total value (sum) of the drive torque TL distributed to the left rear wheel WRL and the drive torque TR distributed to the right rear wheel WRR is constant. To be distributed. And after the time t = ta1, the command value TR (command value before correction) distributed to the right rear wheel WRR is less than the lower limit value (lower limit value per wheel) L1 (= 0). Control for adding the amount below the lower limit L1 (the portion indicated by the hatching in the figure) to the drive torque TL distributed to the left rear wheel WRL on the opposite side is performed. As a result, as shown in FIGS. 6A, 6I, and ii, the total drive torque (left-right sum torque) TA that is actually distributed to the left and right rear wheels WRL, WRR is greater than the required left-right sum torque TM. However, the value DA2 of the required left-right difference torque TS and the realized value DA1 of the left-right difference torque can be made equal (DA1 = DA2).

  That is, in this example, when the required left-right difference torque TS is larger than the required left-right sum torque TM and the command value TR of the drive torque to be distributed to the right rear wheel WRL is below the lower limit value L1, it falls below the lower limit value L1. Is added to the driving torque TL to be distributed to the left rear wheel WRL (added to the amount lower than the lower limit value L1 (negative value) and multiplied by the lower limit adjustment gain Ga (= + 1) (positive value) To maintain the left-right difference.

  In the example shown in FIG. 6B, the upper limit side adjustment gain Gb = + 1. Also in this case, the difference between the drive torque TL allocated to the left rear wheel WRL generated at time t = 0 and the drive torque TR allocated to the right rear wheel WRR gradually changes (increases). Until time t = tb1, the required left-right sum torque TM is a constant value (b0), and the total value (sum) of the drive torque TL distributed to the left rear wheel WRL and the drive torque TR distributed to the right rear wheel WRR. Is distributed to be constant. Then, after time t = tb1, the command value TL (command value before correction) of the drive torque distributed to the left rear wheel WRL exceeds the upper limit value (upper limit value per wheel) L2, so this upper limit value L2 Is controlled to be subtracted from the drive torque TR that is distributed to the right rear wheel WRR (the hatched portion in the figure). As a result, as shown in FIGS. 6B, 6I, and ii, the total drive torque (left-right sum torque) TB actually allocated to the left and right rear wheels WRL, WRR is smaller than the required left-right sum torque TM. However, the value DB2 of the requested left-right difference torque TS and the realized value DB1 of the left-right difference torque can be made equal (DB1 = DB2).

  That is, in this example, when the drive torque TL distributed to the left rear wheel WRL is larger than the upper limit value (upper limit value per wheel) L2, the drive torque that distributes the amount exceeding the upper limit value L2 to the right rear wheel WRR. By subtracting from TL (adding a value (positive value) obtained by multiplying the amount exceeding the upper limit value L2 (negative value) by the upper limit adjustment gain Gb (= + 1)), the left-right difference is maintained. ing.

  FIG. 7 is a diagram (graph) showing another example of a change (change in elapsed time t) of a command value (command torque) of torque distributed to the left and right rear wheels WRL, WRR in the torque distribution control of the present embodiment. It is a figure which shows the left-right sum priority control which gives priority to making the total drive torque (front-back distribution drive torque) distributed to the left and right rear wheels WRL, WRR follow the command value. In both of FIGS. 5A and 5B, the difference between the left and right rear wheels WRL and WRR is prioritized without giving priority to the difference (left-right difference) between the driving torques distributed to the left rear wheel WRL and the right rear wheel WRR. This is a case where control for maintaining the total value of the drive torque (required left-right sum torque TM) is performed. Moreover, (i) of each figure is a graph which shows the change of the request | requirement right-and-left sum torque TM and the request | requirement right-and-left difference torque TS which are the values of the sum and difference of the command torque allocated to each of the left rear wheel WRL and the right rear wheel WRR. (Ii) is a graph showing changes in the required right rear wheel torque TR and the required left rear wheel torque TL, which are command torques distributed to the left rear wheel WRL and the right rear wheel WRR, respectively.

  In the example shown in FIG. 7A, the lower limit side adjustment gain Ga = −1. Also in this case, the difference between the drive torque TL allocated to the left rear wheel WRL generated at time t = 0 and the drive torque TR allocated to the right rear wheel WRR gradually changes (increases). As shown in FIGS. 4A and 4I, the required left-right sum torque TM is a constant value (b0) until time t = ta1, and the drive torque TL distributed to the left rear wheel WRL and the right rear wheel The total value (sum) of the drive torques TR distributed to the WRR is distributed so as to be constant. And after the time t = ta1, the command value (command value before correction) of the drive torque TR distributed to the right rear wheel WRR falls below the lower limit value (lower limit value per wheel) L1 (= 0). Control is performed to subtract the amount below the lower limit value L1 (the portion indicated by the hatching in the figure) from the drive torque TL distributed to the left rear wheel WRL on the opposite side. As a result, as shown in FIGS. 7A, 7I, and ii), the total drive torque (left-right sum torque) of the drive torque TL distributed to the left rear wheel WRL and the drive torque TR distributed to the right rear wheel WRR is obtained. TA can be maintained at a constant value (= b0). On the other hand, the difference value (realized left-right difference torque value) DA1 between the drive torque TL distributed to the left rear wheel WRL and the drive torque TR distributed to the right rear wheel WRR is a target value (the required left-right difference torque TS). Value) A value smaller than DA2 (DA1 <DA2). In addition, after time t = ta2, the value of the required left / right difference torque TS becomes constant, and the total value and the left / right difference are kept constant.

  That is, in this example, when the required left-right difference torque TS is larger than the required left-right sum torque TM and the command value TR of the drive torque distributed to the right rear wheel WRR is below the lower limit value L1, the lower limit value L1 is set. A value (negative value) obtained by subtracting the lower amount from the driving torque TL to be distributed to the left rear wheel WRL (a negative value) obtained by multiplying the lower limit value L1 (positive value) by the lower limit adjustment gain Ga (= -1). The total value is kept constant.

  In the example shown in FIG. 7B, the upper limit side adjustment gain Gb = −1. Also in this case, the difference between the drive torque TL allocated to the left rear wheel WRL generated at time t = 0 and the drive torque TR allocated to the right rear wheel WRR gradually changes (increases). Until time t = tb1, the required left-right sum torque TM is a constant value (b0), and the total value (sum) of the drive torque TL distributed to the left rear wheel WRL and the drive torque TR distributed to the right rear wheel WRR. Is distributed to be constant. Then, after time t = tb1, the command value (command value before correction) of the drive torque TL distributed to the left rear wheel WRL exceeds the upper limit value (upper limit value per wheel) L2, so this upper limit value L2 Is added to the drive torque TR that is distributed to the right rear wheel WRR. As a result, as shown in FIGS. 7B and 7I, the sum of the drive torque distributed to the left rear wheel WRL and the drive torque distributed to the right rear wheel WRR (left-right sum torque) TB is a constant value (= b0). Can be maintained. On the other hand, the difference value (realized left-right difference torque value) DB1 between the drive torque TL distributed to the left rear wheel WRL and the drive torque TR distributed to the right rear wheel WRR shown in FIG. 7 (b) and (i), the target value (the value of the required left-right differential torque TS) is a value smaller than DB2 (DB1 <DB2).

  That is, in this example, when the drive torque TL distributed to the left rear wheel WRL is larger than the upper limit value (upper limit value per wheel) L2, the drive torque that distributes the amount exceeding the upper limit value L2 to the right rear wheel WRR. By adding to TR (adding a value (positive amount) obtained by multiplying the amount exceeding the upper limit value L2 (negative value) by the upper limit adjustment gain Gb (= -1)), the total value is kept constant. It is supposed to be.

  FIG. 8 is a diagram for explaining set values of the lower limit side adjustment gain Ga and the upper limit side adjustment gain Gb. As described above, in the example of FIG. 6A, the value of the lower limit side adjustment gain Ga is set to Ga = + 1, and in the example of FIG. 6B, the value of the upper limit side adjustment gain Gb is set to Gb = + 1. Is set. Further, in the example of FIG. 7A, the value of the lower limit side adjustment gain Ga is set to Ga = −1, and in the example of FIG. 7B, the value of the upper limit side adjustment gain Gb is set to Gb = −1. doing. As shown in FIG. 8, the values of the lower limit adjustment gain Ga and the upper limit adjustment gain Gb can be set based on the value of the lateral acceleration GE and the value of the longitudinal acceleration GH applied to the vehicle.

  That is, in a traveling state where the longitudinal acceleration GH is relatively small and the lateral acceleration GE is relatively large, such as when the vehicle is turning, by setting positive values of Ga, Gb = + 1 to 0 as the values of the adjustment gains Ga, Gb. Left / right difference priority control (controls shown in FIGS. 6A and 6B as an example) is performed. On the other hand, in a traveling state in which the longitudinal acceleration GH is relatively large and the lateral acceleration GE is relatively small, such as during sudden acceleration / deceleration in straight traveling, the values of the adjustment gains Ga, Gb are Ga, Gb = −1 to 0. By setting a negative value, right / left sum (front / rear distribution) priority control (controls shown in FIGS. 7A and 7B as an example) is performed.

  As parameters for determining the values of the adjustment gains Ga and Gb, steering angle data may be used instead of the lateral acceleration GE shown above, or required driving torque data may be used instead of the longitudinal acceleration GH. It may be used. Although the lower limit adjustment gain Ga and the upper limit adjustment gain Gb are set as separate parameters here, the lower limit adjustment gain and the lower limit adjustment gain are set as common parameters. It is also possible.

  9 and 10 are diagrams (graphs) illustrating setting examples of the lower limit side adjustment gain Ga and the upper limit side adjustment gain Gb. 9 and 10 show changes in the torque TL or TR (vertical axis) of one rear wheel (left rear wheel WRL or right rear wheel WRR) with respect to the longitudinal acceleration GH (horizontal axis) during vehicle turning (vertical axis) and lower limit side adjustment. It is a graph which shows the value of the gain Ga and the upper limit side adjustment gain Gb. Here, a case where the vehicle turns (left turn or right turn) at an arbitrary lateral acceleration GE will be described.

  In the example shown in FIG. 9, the value of the lower limit side adjustment gain Ga is set in the range of Ga = + 1 to 0, and the value of the upper limit side adjustment gain Gb is set in the range of Gb = 0 to −1. In this case, when the longitudinal acceleration GH is equal to or less than GH1 (GH1 ≧ GH), if the value of the inner ring torque TR (TL) falls below the lower limit value L1, the portion below the lower limit value L1 (the portion indicated by the oblique lines in the figure). Control to add to the outer ring torque TL (TR) distributed to the opposite wheel is performed. This control gives priority to the drive torque difference (left-right difference) distributed between the left rear wheel WRL and the right rear wheel WRR shown in FIG. 6A, and the drive torque distributed to the left and right rear wheels WRL, WRR. This is a case where control for increasing the total value (required left-right sum torque TM) is performed. Further, when the longitudinal acceleration GH is equal to or higher than GH2 (GH2 ≦ GH), if the value of the outer ring torque TL (TR) exceeds the upper limit value L2, the amount exceeding the upper limit value L2 (the portion indicated by the hatched portion in the figure) is reversed. Control to add to the inner ring torque TR (TL) distributed to the wheel on the side is performed. In this control, the driving torque distributed to the left and right rear wheels WRL and WRR without giving priority to the driving torque difference (left-right difference) distributed between the left rear wheel WRL and the right rear wheel WRR shown in FIG. Is a control for maintaining the total value (required right and left sum torque TM).

  That is, in the example shown in FIG. 9, the value of the rear wheel single wheel torque (TR or TL) reaches the lower limit L1 in the region where the vehicle longitudinal acceleration GH is relatively small (GH1 ≧ GH). Then, by adjusting the value of the lower limit side adjustment gain Ga within a range of Ga = + 1 to 0, right / left difference priority control is performed by adding the amount below the lower limit value to the opposite wheel. Further, the value of the rear wheel single wheel torque (TR or TL) reaches the upper limit value L2 in a region where the longitudinal acceleration GH of the vehicle is relatively large (GH2 ≦ GH). Then, by adjusting the value of the upper limit adjustment gain Gb in the range of Gb = 0 to −1, right / left sum priority (front / rear distribution priority) control is performed by adding the amount exceeding the upper limit to the opposite wheel. Done.

  In the example shown in FIG. 10, the value of the lower limit side adjustment gain Ga is set in the range of Ga = −1 to 0, and the value of the upper limit side adjustment gain Gb is set in the range of Gb = 0 to +1. In this case, when the longitudinal acceleration GH is equal to or less than GH1 (GH1 ≧ GH), if the value of the inner ring torque TR (TL) falls below the lower limit value L1, the portion below the lower limit value L1 (the portion indicated by the oblique lines in the figure). Control is subtracted from the outer ring torque TL (TR) distributed to the opposite wheel. This control gives priority to the difference in drive torque distributed between the left rear wheel WRL and the right rear wheel WRR (left-right difference) shown in FIG. 6 (b), and the drive torque distributed to the left and right rear wheels WRL, WRR. This is a case where control is performed to reduce the total value (required right / left sum torque TM). Further, when the longitudinal acceleration GH is equal to or higher than GH2 (GH2 ≦ GH), if the value of the outer ring torque TL (TR) exceeds the upper limit value L2, the amount exceeding the upper limit value L2 (the portion indicated by the hatched portion in the figure) is reversed. Control to subtract from the inner ring torque TR (TL) distributed to the side wheel. In this control, the driving torque distributed to the left and right rear wheels WRL and WRR without giving priority to the driving torque difference (left-right difference) distributed between the left rear wheel WRL and the right rear wheel WRR shown in FIG. Is a control for maintaining the total value (required right and left sum torque TM).

  That is, also in the example shown in FIG. 10, the value of the rear wheel single wheel torque (TR or TL) reaches the lower limit L1 in a region where the vehicle longitudinal acceleration GH is relatively small (GH1 ≧ GH). Then, by adjusting the value of the lower limit side adjustment gain Ga within the range of Ga = −1 to 0, right / left difference priority control is performed by subtracting the amount below the lower limit value from the opposite wheel. On the other hand, the value of the rear wheel single wheel torque (TR or TL) reaches the upper limit value L2 in a region where the vehicle longitudinal acceleration GH is relatively large (GH2 ≦ GH). Then, by adjusting the value of the upper limit adjustment gain Gb in the range of Gb = 0 to +1, right / left sum priority (front / rear distribution priority) control is performed by subtracting the amount exceeding the upper limit from the wheel on the opposite side. .

  As described above, according to the torque distribution control device for a four-wheel drive vehicle of this embodiment, the left and right distribution drive torques TL and TR (left drive torque and right drive torque) distributed to the left and right auxiliary drive wheels WRL and WRR, respectively. ) Command value (difference between left and right) is generated, and this difference is changed (increased) to distribute the front / rear distribution drive torques TM, TS (main drive wheel torque and sub drive wheels) distributed to the sub drive wheels WRL, WRR. When the torque exceeds the command value, it is possible to select either the left / right difference priority control or the left / right sum priority control according to the running state of the vehicle. When performing this, optimal torque distribution control can be performed. Therefore, it is possible to effectively prevent the behavior of the vehicle from becoming unstable and improve the running performance of the vehicle.

  Further, in the torque distribution control device of the present embodiment, the command values of the left and right distribution drive torque distributed to either one of the left and right auxiliary drive wheels WRL, WRR (requested right rear wheel torque TR, requested left rear wheel torque TS). When the value exceeds the predetermined limit values L1 and L2, the amount exceeding the limit values L1 and L2 is set to the other of the left and right auxiliary drive wheels WRL and WRR (the opposite auxiliary drive wheel). The control value to be added to or subtracted from the left and right distributed drive torque distributed to the left and right auxiliary drive wheels WRL, WRR is determined by a predetermined limit value. When the value exceeds the value, the difference between the drive torques distributed to the left and right auxiliary drive wheels WRL and WRR (left and right difference), or the drive allocated to the main drive wheels WFL and WFR and the auxiliary drive wheels WRL and WRR, respectively. It is possible to maintain the difference in torque (the differential). Therefore, more optimal torque distribution control can be performed.

  Further, in the torque distribution control device of the present embodiment, the left-right difference priority control described above is performed in a traveling state in which the longitudinal acceleration GH of the vehicle is relatively small and the lateral acceleration GE is relatively large, such as when the vehicle is turning, and the vehicle travels straight. In a traveling state where the longitudinal acceleration GH of the vehicle is relatively large and the lateral acceleration GE is relatively small, such as during sudden acceleration / deceleration during traveling, the left / right sum priority control is performed. In this way, when the front / rear distribution drive torque distributed to the auxiliary drive wheels WRL, WRR exceeds the command value, the shortage of the left / right distribution drive torque is added to the distribution amount to the left and right opposite drive wheels. Priority is given to either left / right difference priority control that prioritizes left / right difference or left / right sum priority control that prioritizes front / rear difference (front / rear distribution) by subtracting the insufficient amount of left / right distribution drive torque from the distribution amount to the opposite drive wheels. The priority can be varied according to the driving condition (running state) of the vehicle. Therefore, more optimal drive torque distribution control can be performed in accordance with the running conditions of the vehicle.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the technical idea described in the claims and the specification and drawings. Is possible. For example, the specific numerical values of the drive torque command values shown in the above-described embodiments are examples, and the specific values are other numerical values as long as the drive torque command values are values within the scope of the present invention. There may be.

  Further, the specific configuration of the driving force transmission system shown in the present embodiment is an example, and the configuration of the driving force transmission system for carrying out the driving force distribution control according to the present invention is either a front wheel or a rear wheel. In a four-wheel drive vehicle in which one is a main drive wheel and the other is a sub drive wheel, a front and rear torque distribution device for distributing drive torque transmitted to one and the other of the main drive wheel and the sub drive wheel, As long as the configuration includes a left / right torque distribution device for distributing the drive torque transmitted to one and the other of the auxiliary drive wheels, the specific configuration is different from that shown in the above embodiment. May be.

11 Front differential gears 12, 12 Front drive shaft 13 Front propeller shaft 14 Speed increasing device (front / rear torque distribution device)
15 Rear propeller shaft 16 Rear differential gear (left and right torque distribution device)
17L, 17R Rear drive shaft 21 Planetary gear mechanism 22 Speed increasing clutch 23 Direct coupling clutch 24 Input side sun gear 25 Output side sun gear 26 Carrier 27 Dual pinion 27a Input side pinion 27b Output side pinion 28 Housing 29 Clutch outer 30 Clutch inner 31 Friction engagement Coupling element 32 Clutch outer 33 Clutch inner 34 Friction engagement element 35 One-way clutch 36 Input shaft 37 Driven bevel gear 38 Drive bevel gear 39 Planetary gear mechanisms 40L, 40R Torque distribution clutch (torque distribution device)
41 Ring gear 42 Carrier 43 Sun gear 44 Pinion 45 Housing 46 Clutch outer 47 Clutch inner 48 Friction engagement elements 49L and 49R Electromagnetic actuator 51 Input section 52a Vehicle speed sensor 52b Steering angle sensor 53 Estimated drive torque calculation section 54 Stabilization control section 55 Increase Speed control unit 56 LSD control unit 57 Torque addition unit 58 Climbing control unit 60 Clutch torque limiting unit 61 Current control unit 62 Drive circuit unit T Automatic transmission Ua Electronic control unit (4WD-ECU, control means)
WFL, WFR Front wheel (main drive wheel)
WRL, WRR Rear wheel (sub drive wheel)
L1 Lower limit L2 Upper limit

Claims (3)

In a four-wheel drive vehicle in which one of the front wheels and the rear wheels is the first drive wheel and the other is the second drive wheel,
Front and rear torque distribution devices for distributing and transmitting first drive wheel torque and second drive wheel torque to each of the first drive wheel and the second drive wheel;
A left and right torque distribution device for distributing and transmitting left drive torque and right drive torque to each of the left second drive wheel on the left side of the second drive wheel and the right second drive wheel on the right side;
Control means for controlling the first drive wheel torque and the second drive wheel torque distributed by the front and rear torque distribution device, and the left drive torque and the right drive torque distributed by the left and right torque distribution device;
As a means for determining a traveling state of the vehicle, a torque distribution control apparatus Ru comprising a lateral acceleration determining means, the determining the lateral acceleration and the longitudinal acceleration determining means, said vehicle for determining a longitudinal acceleration of the vehicle And
The control means includes
When the difference between the command value for the left drive torque and the command value for the right drive torque changes, the second drive wheel torque, which is the sum of the left drive torque and the right drive torque, becomes the second drive wheel. If it exceeds the torque command value,
Depending on the driving condition of the vehicle,
Left / right difference priority control that prioritizes the difference between the left driving torque and the right driving torque to follow the difference between the left driving torque command value and the right driving torque command value ;
Select either left-right sum priority control that prioritizes the sum of the left drive torque and the right drive torque to follow the sum of the command value of the left drive torque and the command value of the right drive torque. There line,
In a driving state where the longitudinal acceleration of the vehicle is relatively small and the lateral acceleration is relatively large, the left-right difference priority control is performed,
The torque distribution control device for a four-wheel drive vehicle , wherein the left-right sum priority control is performed in a traveling state where the longitudinal acceleration of the vehicle is relatively large and the lateral acceleration is relatively small . The left / right difference priority control is:
When one of the command value for the left drive torque and the command value for the right drive torque falls below a predetermined lower limit value, the amount below the lower limit value is set to an amount that is less than the lower limit value. Control to add to the other of the command value, or
When one of the command value for the left drive torque and the command value for the right drive torque exceeds a predetermined upper limit value, the amount exceeding the upper limit value is set to an amount exceeding the upper limit value. The torque distribution control device for a four-wheel drive vehicle according to claim 1, wherein the control is subtracted from the other command value. The left-right sum priority control is
When one of the command value for the left drive torque and the command value for the right drive torque falls below a predetermined lower limit value, the amount below the lower limit value is set to an amount that is less than the lower limit value. Control subtracted from the other of the command value, or
When one of the command value for the left drive torque and the command value for the right drive torque exceeds a predetermined upper limit value, the amount exceeding the upper limit value is set to an amount exceeding the upper limit value. The torque distribution control device for a four-wheel drive vehicle according to claim 1, wherein the control is added to the other of the command value.

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