JP2008254458A - Control device of driving force distribution device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device of a driving force distribution device for a vehicle capable of performing control with high accuracy for distributing the driving force to left and right drive wheels. <P>SOLUTION: A drive torque distribution ratio RHratio of left and right front wheels 20l and 20r by a front wheel differential gear device (mechanical differential device) 16 is calculated by a drive torque distribution ratio calculation means 78 (S3), and a first clutch C1 and a second clutch C2 (left and right drive torque difference adjustment device) are controlled so as to obtain target left and right drive torque difference ΔT* based on the drive torque distribution ratio RHratio of the left and right front wheels 20l and 20r and the target left and right drive torque difference ΔT* by a left and right drive torque difference control means 82 (S7). Therefore, control with high accuracy for distributing drive torque to left and right rear wheels 30l and 30r can be obtained. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a control device for a vehicle drive force distribution device that distributes input torque input from a drive source to left and right drive wheels.

2. Description of the Related Art A vehicle driving force distribution device that distributes driving force generated by a driving source such as an engine to left and right wheels via a mechanical differential device is known. For example, the apparatus described in Patent Document 1 is an example. Such a vehicle driving force distribution device includes an engagement element for limiting the differential between the left and right drive wheels, and in order to improve the operability and running stability of the vehicle, the engagement of the engagement element is provided. For example, the torque is controlled so as to obtain a target left-right torque difference between the left and right drive wheels.
JP-A-11-105573

  By the way, using the vehicle drive force distribution device as described above, the drive force is distributed to the left and right drive wheels by the mechanical differential device, and the slip of the engagement element that generates a torque difference between the left and right drive wheels. Control is performed to obtain a required left-right torque difference, that is, a target left-right torque difference by increasing or decelerating one of the drive wheels with respect to the other using the engagement. However, in the control device of the conventional vehicle driving force distribution device, the inherent differential limiting torque or the lock rate provided in the mechanical differential device is not considered, and sufficient control accuracy is not necessarily obtained. In some cases, it has not been possible to obtain a target left-right torque difference stably.

  As a result of various studies conducted on the basis of the above circumstances, the present inventors have found that the left and right driving torque difference constituted by an engagement element or the like is obtained in a vehicle equipped with a mechanical differential device so as to obtain a target left and right torque difference. When control is performed using the control amount calculated to control the adjusting device, if the differential limit torque based on the control amount is corrected in consideration of the differential limit torque of the mechanical differential device, driving is performed. We found the fact that the control accuracy of distribution control can be suitably obtained for the left and right driving wheels. The present invention has been made based on such knowledge.

  That is, an object of the present invention is to provide a control device for a vehicle driving force distribution device capable of highly accurate control for distributing driving force to left and right driving wheels.

  To achieve this object, the gist of the invention according to claim 1 is that a mechanical differential device that distributes input torque input from a drive source to left and right drive wheels, and drive torque of left and right drive wheels A vehicle driving force distribution device that controls the left-right driving torque difference adjusting device so as to obtain a target left-right driving torque difference obtained in advance. (A) a drive torque distribution ratio calculating means for calculating a drive torque distribution ratio of the left and right drive wheels by the mechanical differential device; and (b) calculated by the drive torque distribution ratio calculating means. Based on the drive torque distribution ratio of the left and right drive wheels by the mechanical differential device and the target left / right drive torque difference, the left / right drive torque difference adjusting device is controlled so as to obtain the target left / right drive torque difference. And left and right drive torque difference control means is to include.

  According to the control device for a vehicle driving force distribution device according to the first aspect of the present invention, the drive torque distribution ratio calculation means calculates the drive torque distribution ratio of the left and right drive wheels by the mechanical differential, and the right and left The left and right drive torque difference adjusting device controls the left and right drive wheel difference control means to obtain the target left and right drive torque difference based on the drive torque distribution ratio between the left and right drive wheels and the target left and right drive torque difference. Therefore, highly accurate control for distributing the drive torque to the left and right drive wheels can be obtained.

  Here, preferably, (a) an operation for determining an operation state of the mechanical differential device based on the positive / negative of the drive state by the mechanical differential device and the difference in rotational speed between the left and right drive wheels (B) the drive torque distribution ratio calculating means includes a mechanical difference set in advance, based on a relationship that takes into account the operating state of the mechanical differential device determined by the operating state determining means. A drive torque distribution ratio of the left and right drive wheels by the mechanical differential device is calculated based on a lock rate of a moving device. According to this configuration, based on the relationship in which the operating state of the mechanical differential device determined by the operating state determining unit is taken into account, the mechanical differential device is operated based on the preset lock rate of the mechanical differential device. Since the drive torque distribution ratio of the left and right drive wheels is calculated, the left and right drive torque difference adjustment is performed based on the drive torque distribution ratio and the target left and right drive torque difference so that the target left and right drive torque difference is obtained. Since the device is controlled, highly accurate control for distributing the drive torque to the left and right drive wheels can be obtained.

  Preferably, (a) the operation state determination means is configured so that the mechanical differential is in a positive drive state or a negative drive state, and a difference in rotational speed between the left and right drive wheels is equal to or greater than a predetermined value. (B) the driving torque distribution ratio calculating means is a plurality of operating states of the mechanical differential device determined by the operating state determining means. From the relationship in consideration of the above, a torque distribution rate of one of the left and right drive wheels is calculated based on a preset lock rate of the mechanical differential, and a torque distribution rate of the other drive wheel Is calculated. According to this configuration, the left and right driving are performed based on the preset lock rate of the mechanical differential device from the relationship in consideration of the plurality of operating states of the mechanical differential device determined by the operating state determining means. Since the drive torque distribution ratio of one of the wheels is calculated, the left and right drive torque differences are obtained based on the drive torque distribution ratio and the target left / right drive torque difference. Since the drive torque difference adjusting device is controlled, high-accuracy control for distributing the drive torque to the left and right drive wheels can be obtained.

  Preferably, (a) a correction value calculation means for calculating a correction value based on the torque distribution rate of the one drive wheel, the torque distribution rate of the other drive wheel, and the input torque of the mechanical differential device (B) The left-right drive torque difference control means calculates a correction value calculated by the correction value calculation means for a control amount for the left-right drive torque difference adjustment device so that a target left-right drive torque difference is obtained. The left / right driving torque difference adjusting device is controlled using the corrected control amount corrected in step (1). In this way, the correction value is calculated based on the torque distribution rate of one drive wheel, the torque distribution rate of the other drive wheel, and the input torque of the mechanical differential, so that the target left-right drive Since the correction value for controlling the left / right driving torque difference adjusting device is corrected by the correction value so that the torque difference is obtained, the left / right driving torque difference adjusting device is controlled using the corrected control amount, and the left / right driving torque difference adjusting device is controlled. High-precision control that distributes the drive torque to the drive wheels is obtained.

  Preferably, (a) the mechanical differential device distributes input torque input from a drive source to one of the left and right drive wheels of the front and rear wheels of the vehicle, and (b) The left / right driving torque difference adjusting device adjusts a driving torque difference between the left and right driving wheels of the other of the front wheel and the rear wheel. In this way, in a four-wheel drive vehicle, it is possible to obtain highly accurate control that distributes the drive torque to the left and right drive wheels to obtain the target left / right drive torque difference.

  Preferably, (a) the mechanical differential device distributes input torque input from a drive source to the left and right drive wheels of the front wheel of the vehicle, and (b) the left and right drive torque difference The adjusting device adjusts the driving torque difference between the left and right driving wheels of the rear wheel of the vehicle. In this manner, in the four-wheel drive vehicle, the difference in drive torque between the left and right drive wheels of the rear wheel is adjusted, so that the drive torque is distributed to the left and right drive wheels to obtain the target left and right drive torque difference. Control of accuracy is obtained.

  Preferably, (a) a differential device that distributes input torque input from the drive source to the other left and right drive wheels, and an input member that is input from any of the rotating elements of the differential device And a pair of engagements provided between an output member of the transmission and at least one of the left and right drive wheels. And (b) the left and right driving torque difference adjusting device is composed of a pair of engaging elements. In this way, the drive torque difference between the left and right drive wheels of the rear wheel is adjusted using the pair of engagement elements, so that the drive torque is applied to the left and right drive wheels to obtain the target left and right drive torque difference. High precision control of dispensing is obtained.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a skeleton diagram illustrating the configuration of a front and rear wheel drive vehicle based on a front engine front wheel drive (FF) having a driving force transmission device 10 to which the present invention is preferably applied. In FIG. 1, the driving force (torque) generated by the engine 12 serving as a driving force source includes a torque converter 13, an automatic transmission 14, a front wheel differential gear device 16, and a pair of left and right front wheel axles 18l. 18r (hereinafter simply referred to as front wheel axle 18 unless otherwise distinguished) is transmitted to a pair of left and right front wheels 20l and 20r (hereinafter simply referred to as front wheel 20 unless otherwise distinguished). A differential gear device (center differential) 22, a propeller shaft 24 as a driving force transmission shaft, a vehicle driving force distribution device (hereinafter simply referred to as a driving force distribution device) 26 according to an embodiment of the present invention, and a pair of left and right A pair of left and right rear wheels 30l, 30r (hereinafter not particularly distinguished through rear wheel axles 28l, 28r (hereinafter simply referred to as rear wheel axle 28 unless otherwise distinguished). Is simply transmitted to the rear of wheel 30). Here, as shown in FIG. 1, in the driving force transmission device 10 of the present embodiment, the rotational axis of the rear wheel 30 as the driving wheel related to the distribution of the driving force by the vehicle driving force distribution device 26 and the propeller. It arrange | positions so that the rotating shaft center of the shaft 24 may mutually orthogonally cross. The driving force transmission device 10 includes a hydraulic circuit 34 that controls the hydraulic pressure supplied into the driving force distribution device 26 and an unillustrated electromagnetic control valve provided in the hydraulic circuit 34. An electronic control device 36 that controls the hydraulic pressure supplied from the circuit 34 into the driving force distribution device 26 is provided. In FIG. 1, the hydraulic pressure output from the hydraulic circuit 34 is indicated by a thin line arrow, and the control command output from the electronic control unit 36 is indicated by a thin broken line arrow.

  The engine 12 is, for example, an internal combustion engine such as a gasoline engine or a diesel engine that generates driving force by combustion of fuel injected in a cylinder. Further, the automatic transmission 14 outputs, for example, a rotation input from the engine 12 by decelerating or increasing the speed at a predetermined speed ratio γ selected from speed ratios corresponding to a plurality of speed stages. Type automatic transmission (automatic transmission), and any one of the forward gear, the reverse gear, and the neutral is selectively established, and the speed conversion corresponding to the respective gear ratio γ is performed. The input shaft of the automatic transmission 14 is connected to the output shaft of the engine 12 via the torque converter 13 and the like.

  The front wheel differential gear device 16 is, for example, a mechanical differential composed of a differential mechanism such as a Torsen differential gear device (Torsen differential) with a frictional differential limiting function or a planetary gear differential gear device. Device. Thus, the front wheel differential gear device 16 composed of the mechanical differential device generates a relatively large differential limiting torque derived from the mechanism, and has a constant lock ratio LE (%) [= (Differential limit torque of mechanical differential device / input torque to mechanical differential device) × 100] Since the differential limiting torque is a function that increases with the input torque of the differential gear device, the magnitude of the differential limiting torque is expressed by a constant lock ratio LE. Not only the Torsen differential but also a normal planetary gear type differential device generates a certain amount of differential limiting torque due to its mechanism.

  FIG. 2 is a skeleton diagram showing an example in which the front wheel differential gear device 16 is composed of a Torsen-type differential gear device. In FIG. 2, the front-wheel differential gear device 16 has a common shaft center with front-wheel axles 18l and 18r via a large-diameter input gear 40 that meshes with a pinion 38 operatively connected to the output shaft of the automatic transmission 14. The left side gear 44 connected to the front wheel axle 18l, the left pinion gear 46 meshed with the left side gear 44, the right side gear 48 linked to the front wheel axle 18r, and the right pinion gear 50 meshed with the right side gear 48. ing. The differential case 42 rotatably supports the left side gear 44 and the right side gear 48, the left pinion gear 46 and the right pinion gear 50, and supports the left pinion gear 46 and the right pinion gear 50 so as to be capable of revolving on an axis. The outer peripheral teeth of the left side gear 44 and the right side gear 48 and the left pinion gear 46 and the right pinion gear 50 are constituted by helical teeth having a predetermined torsion angle.

  The outer peripheral teeth of the left pinion gear 46 are composed of outer peripheral teeth 46 a and 46 b formed at two locations spaced in the axial direction, and the outer peripheral teeth 46 a formed on the front wheel axle 18 l side are It is meshed with the peripheral teeth. Further, the outer peripheral teeth of the right pinion gear 50 are constituted by outer peripheral teeth 50a and 50b formed at two locations spaced in the axial direction, and the outer peripheral teeth 50a formed on the front wheel axle 18r side are the right side gear 48. Is meshed with the outer peripheral teeth. Further, the outer peripheral teeth 46a of the left pinion gear 46 and the outer peripheral teeth 50b formed on the left front wheel axle 18l side of the right pinion gear 50 are meshed, and the outer peripheral teeth 50a of the right pinion gear 50 and the right front wheel axle 18r of the left pinion gear 46 are engaged. The outer peripheral teeth 46b formed on the side are meshed with each other. As a result, the left pinion gear 46 and the right pinion gear 50 are rotated in opposite directions.

  Further, the outer peripheral teeth 46 a of the left pinion gear 46 and the left side gear 44 are meshed, but the right pinion gear 50 is not provided with outer peripheral teeth that can mesh with the left side gear 44. Similarly, the outer peripheral teeth 50 a of the right pinion gear 50 and the right side gear 48 are meshed, but the left pinion gear 46 is not provided with outer peripheral teeth that can mesh with the right side gear 48.

  The differential case 42 includes a plurality of pairs of a left side gear 44 and a right side gear 48 that are arranged so as to be adjacent to each other in the circumferential direction around the axial center of the front wheel axles 18l and 18r. The left pinion gear 46 and the right pinion gear 50 are supported so as to be able to revolve and rotate about the shaft centers of the front wheel axles 18l and 18r, respectively. Further, the wall surface of the differential case 42 is formed so as to be in sliding contact with the side walls of the left side gear 44 and the right side gear 48 and the tooth tips of the outer peripheral teeth so that differential limiting torque is generated mechanically.

  Returning to FIG. 1, the electronic control unit 36 includes a CPU, a ROM, a RAM, an input / output interface, and the like, and executes signal processing according to a program stored in advance in the ROM while using a temporary storage function of the RAM. A so-called microcomputer, for example, a hydraulic friction engagement described later provided in the driving force distribution device 26 by controlling a command value of a current supplied to an electromagnetic control valve provided in the hydraulic circuit 34 By controlling the hydraulic pressure supplied to the clutches C1 and C2 and the brake BK, which are the devices, left and right wheel torque difference control, differential restriction control, and the like, which will be described later, are executed. The driving force transmission device 10 includes a wheel speed sensor that detects an actual rotational speed of the rear wheel 30 corresponding to a vehicle speed, a shift stage sensor that detects a shift stage of the automatic transmission 14, and an air supply / exhaust of the engine 12. A throttle sensor for detecting the actual opening of a throttle valve (not shown) provided in the pipe, an engine rotational speed sensor for detecting the actual rotational speed of the engine 12, a front-rear G sensor, and the like are provided. A signal representing the vehicle speed, a signal representing the shift stage, a signal representing the throttle opening, a signal representing the engine speed, a signal representing the longitudinal acceleration, and the like are supplied to the electronic control unit 36.

  FIG. 3 is a skeleton diagram illustrating the configuration of the driving force distribution device 26. As shown in FIG. 3, the driving force distribution device 26 includes a bevel gear 58 connected to the end of the propeller shaft 24 that is rotationally driven from the engine 12 via the central differential gear device 22, and the bevel gear. The driving force is transmitted to the driving force distribution device 26 via the bevel gear 60 that meshes with the driving force 58. The driving force distribution device 26 includes a differential device (differential mechanism) 62 for distributing the driving force to the left and right rear wheels 30l and 30r via a pair of rear wheel axles 28l and 28r, and the differential device 62. Adjacent to the rear wheel axles 28l and 28r and coaxially disposed on the rear wheel axles 28l and 28r, and the output of the transmission 64 is selectively transmitted to a pair of rear wheel axles 28l and 28r which are output shafts of the differential device 62. The first clutch C1 and the second clutch C2 are provided. The differential device 62 of the present embodiment corresponds to the differential portion of the driving force distribution device 26, the transmission device 64 corresponds to the transmission portion of the driving force distribution device 26, and the first clutch C1 and the second clutch C2 are This is an engagement element for generating a torque difference between the left and right rear wheels 30l, 30r, and corresponds to a left / right driving force difference adjusting device.

  The differential device 62 includes a ring gear R1 that is a first rotating element RE1, a plurality of pairs of pinion gears P1 that mesh with each other, a carrier CA1 that is a second rotating element RE2 that supports the pinion gears P1 so as to rotate and revolve, and the plurality of pairs. Is a double-pinion type planetary gear device having a sun gear S1 that is a third rotating element RE3 that meshes with the ring gear R1 via the pinion gear P1, and the gear ratio ρ is (= the number of teeth of the sun gear S1 / the number of teeth of the ring gear R1). ) Is set to 0.5, for example. The ring gear R1 is provided integrally with the case 66 inside the case 66 of the differential device 62, and the rotation of the propeller shaft 24 is reduced by the bevel gears 58 and 60 and transmitted. That is, power from the engine 12 as a drive source is input to the ring gear R1 via the propeller shaft 24. The carrier CA1 is connected to the left rear wheel 30l via the left rear wheel axle 28l. The sun gear S1 is connected to the right rear wheel 30r via the right rear wheel axle 28r. The second rotation element RE2 and the third rotation element RE3 can be replaced, and the same applies to the following description.

  The transmission 64 meshes with a small-diameter pinion P2 that meshes with the large-diameter sun gear S2 that is coupled to the case 66, and a small-diameter sun gear S3 that is coupled to the first clutch C1 and the second clutch C2, and that corresponds to the fourth rotation element RE4. A large-diameter pinion P3 that is larger in diameter than the small-diameter pinion P2 and is integrally connected to the small-diameter pinion P2, and the small-diameter pinion P2 and the large-diameter pinion P3 that are integrally connected to each other can rotate. A carrier CA2 that is supported so as to be capable of revolving, and a brake BK that is provided between the carrier CA2 and a non-rotating member 55 such as a housing and that selectively disables the carrier CA2 from rotating. It operates as a speed increasing transmission. The carrier CA2 corresponds to the fifth rotation element RE5, and the small-diameter pinion P2 functions as an input member of the transmission 64, and the large-diameter pinion P3 functions as an output member of the transmission 64.

  Each of the brake BK, the first clutch C1, and the second clutch C2 is a multi-plate hydraulic friction engagement device capable of slip engagement, and is engaged by a control valve in a hydraulic circuit 34 controlled by the electronic control device 36. By controlling the combined hydraulic pressure, it is engaged or released according to the command of the electronic control unit 36, and the transmission torque is controlled in the slip engagement state by controlling the hydraulic pressure of the engagement pressure.

The distribution of the driving force to the left and right rear wheels 30l and 30r by the driving force distribution device 26 configured as described above will be described. The driving force generated by the engine 12 is input as a driving force for rotationally driving the case 66 via the automatic transmission 14, the transfer or central differential gear device 22, the propeller shaft 24, and the like. Since the ring gear R1 of the differential device 62 is provided integrally with the case 66, all or part of the driving torque T _IN (Nm) input from the propeller shaft 24 to the ring gear R1 and the case 66 is the differential device. 62.

When the brake BK, the first clutch C1, and the second clutch C2 are in the disengaged state, the transmission device 64 is idling and only the differential device 62 functions. all of the drive torque _{T iN} is transmitted to the differential device 62, the left and right rear wheels 30l, while relative rotation 30r is allowed their left and right rear wheels 30l, is uniformly distributed with respect to 30r. Thus, the driving force distribution device 26 functions as a normal open differential without torque movement and differential limitation. Therefore, during straight running, the differential device 62 is integrally rotated, and the rotational speeds Nl and Nr (rpm) of the left and right rear wheels 30l and 30r are substantially the same.

  During the differential limiting control, the brake BK is released while the first clutch C1 and the second clutch C2 are engaged. By engaging the first clutch C1 and the second clutch C2, differential limiting of the left and right rear wheels 30l and 30r is performed. When the clutches C1 and C2 are completely engaged, the driving force distribution device 26 functions as a non-slip differential, and the left and right rear wheels 30l and 30r rotate in the same direction. The differential limiting force can be arbitrarily set in proportion to the clutch control torque.

  During turning of the vehicle, for example, when turning left, the torque of the right rear wheel 30r is increased in order to suppress understeer of the vehicle. In this case, the brake BK is engaged and the transmission 64 functions as a speed increasing transmission that increases the speed Ns2 (rpm) of the case 66, that is, the sun gear S2, and transmits it to the sun gear S3, and the second clutch C2 The slip engagement is established and the first clutch C1 is released. When the brake BK is engaged, the carrier CA2 of the transmission 64 is locked, and the rotation speed Ns3 (rpm) of the fourth rotation element RE4 is increased in the same rotation direction and output. As the second clutch C2 is slip-engaged, the output of the fourth rotation element RE4 is transmitted to the sun gear S1 that is the first rotation element RE1. Here, since the rotation speed Ns3 of the fourth rotation element RE4 is increased in the same rotation direction, the slip engagement of the second clutch C2 increases the torque of the right rear wheel 30r, and the left rear wheel 30l. Torque is relatively reduced. Further, since the rotational speed Nr of the right rear wheel 30r is increased by slip engagement of the second clutch C2, the rotational speed Nl of the left rear wheel 30l is decelerated by the differential device 62.

  On the contrary, during a right turn, the torque of the left rear wheel 30l is increased in order to suppress understeer of the vehicle. In this case, the brake BK is engaged, and the transmission 64 functions as a speed increasing transmission that increases the speed Ns2 of the case 66, that is, the sun gear S2, and transmits it to the sun gear S3, and the first clutch C1 is slip-engaged. Then, the second clutch C2 is released. When the brake BK is engaged, the carrier CA2 of the transmission 64 is locked, and the rotation speed Ns3 of the fourth rotation element RE4 is increased in the same rotation direction and output. As the first clutch C1 is slip-engaged, the output of the fourth rotating element RE4 is transmitted to the carrier CA1 that is the second rotating element RE2. Here, since the rotation speed Ns3 of the fourth rotation element RE4 is increased in the same rotation direction, the slip engagement of the first clutch C1 increases the torque of the left rear wheel 30l, and the right rear wheel 30r Torque is relatively reduced. Further, since the rotational speed Nl of the left rear wheel 30l is increased by slip engagement of the first clutch C1, the rotational speed Nr of the right rear wheel 30r is decelerated by the differential device 62.

FIG. 4 is a functional block diagram illustrating a main part of the control function of the electronic control unit 36. In FIG. 4, the target yaw rate calculating means 70 is a target yaw rate r for setting a neutral steer between the understeer and the oversteer based on the steering angle δ of the steering wheel based on the prestored relationship during turning of the vehicle. ^* Is calculated. The target left-right torque difference calculating means 72 has a yaw rate deviation Δr (= r ⁾ between a target yaw rate r ^* calculated by the target yaw rate calculating means 70 and an actual yaw rate r output from a yaw rate sensor (not shown) based on a previously stored relationship. Based on ^* −r), a target left-right torque difference ΔT ^* for eliminating the yaw rate deviation Δr is calculated.

The input torque calculating means 74 calculates an input torque T _QF to the front wheel differential gear device 16 which is a mechanical differential device. For example, the engine output torque _TE is calculated based on the actual throttle opening θ and the engine speed NE from the relationship stored in advance, and then the torque ratio t of the torque converter 13 and the gear ratio γ ₁₄ of the automatic transmission 14 are calculated. is calculated from such a gear ratio gamma _F of the transmission system to the differential case 42 of the front wheel differential gear device 16, on the basis of the above engine output torque T _E, the input torque T to the front wheel differential gear device 16 _QF (= γ _F · T _E ) is calculated. The torque ratio t of the torque converter 13 is calculated from the relationship stored in advance with the input shaft rotational speed of the torque converter 13, that is, the engine rotational speed NE, and the output shaft rotational speed of the torque converter 13, that is, the input shaft rotational speed of the automatic transmission 14. Is calculated based on Further, the gear ratio γ ₁₄ of the automatic transmission 14 is calculated based on the input shaft rotation speed and the output shaft rotation speed (vehicle speed) of the automatic transmission 14 from a previously stored relationship.

The operating state discriminating means 76 determines whether the operating state of the front wheel differential gear device 16 is one of a plurality of preset states, for example, the difference in rotational speed between the left and right front wheels 20l, 20r or the steering wheel steering. a straight or turning traveling state of the vehicle corners δ is determined based on whether or not preset turning decision value or more, the drive is determined on the basis of the engine output torque T _E (power-on: accelerated running) Or it determines based on a non-drive (coast: coasting) state. For example, the operating state determination unit 76 is in a state where the front wheel differential gear device 16 is traveling straight and distributing drive torque, or is traveling straight and distributing negative torque. Whether the vehicle is turning right and distributing driving torque, or is turning right and distributing negative torque, or turning left and driving torque. It is determined whether or not the vehicle is in a state of distributing a negative torque.

  The drive torque distribution ratio calculation means 78 determines the drive torque distribution ratio to the left and right front wheels 20l and 20r, which takes into account the differential limiting torque that is mechanically generated in the front wheel differential gear device 16. This drive torque distribution ratio is represented by a distribution ratio RHratio (%) to the right front wheel 20r and / or a distribution ratio RLHratio (%) to the left front wheel 20l. The drive torque distribution ratio calculation means 78 is an approximation selected based on the differential state determined by the operating state determination means 76 from a plurality of types of approximate expressions stored in advance, for example, the following expressions (1) to (3). From the approximate expression, the distribution ratio RHratio to the right front wheel 20r is calculated based on the lock ratio LE of the front wheel differential gear device 16 and the actual left and right installation load, and the distribution ratio to the right front wheel 20r. A distribution ratio RLHratio (= 100−RHratio) to the left front wheel 20l is calculated from RHratio. The drive torque distribution ratio calculating means 78 selects the expression (1) for straight traveling, selects the expression (2) for right turning, and selects the expression (3) for left turning. . These equations (1) to (3) are relationships that take into account the differential limiting torque that is mechanically generated in the front-wheel differential gear unit 16. In equations (1) to (3), the ground load ratio WfRHratio (%) of the right front wheel 20r is (WfRH / Wf0), where Wf0 is the total ground load of the front wheel and WfRH is the ground load of the right front wheel 20r. X100. LE is a lock ratio indicating the mechanical differential limiting torque characteristic of the differential gear device 16 for the front wheels.

RHratio = Wfratio ≒ 50 (1)
RHratio = (50 + LE / 2) (2)
RHratio = (50−LE / 2) (3)

  Equation (4) shows the contact load of the right front wheel 20r for calculating WfRH, and Equation (5) shows the contact load of the left front wheel 20l for calculating WfLH. In Expressions (4) and (5), H is the height of the center of gravity of the vehicle, W is the front and rear ground contact load of the vehicle, L is the wheel base, R is the height of the roll center, and T is the tread.

WfRH = (Wf0−H / L × GX × W) / 2 × (1 + R / T × Gy) (4)
WfLH = (Wf0−H / L × GX × W) / 2 × (1-R / T × Gy) (5)

The correction value calculation means 80 uses, for example, a previously stored correction value ΔT2 corresponding to the differential limiting torque mechanically generated in the front-wheel differential gear device 16 used in the left / right drive torque distribution control, for example, the following equation (6 ), The distribution ratio RHratio to the right front wheel 20r and the distribution ratio RLHratio to the left front wheel 20l calculated by the drive torque distribution ratio calculation means 78, and the front wheel differential gear device 16 calculated by the input torque calculation means 74. It is calculated based on the input torque T _QF to.

_{ΔT2 = (RHratio -RLHratio) × T} QF ··· (6)

The left-right drive torque difference control means 82 is a target left-right torque difference ΔT ^* calculated by the target left-right torque difference calculation means 72, that is, a required left-right torque difference ΔT _REQ , Based on the correction value ΔT2 calculated by the correction value calculation means 80, the required engagement torque T _CREQ required for the first clutch C1 or the second clutch C2 is used as the control amount of the first clutch C1 or the second clutch C2. While calculating, the required engagement torque T _CREQ is output to the hydraulic circuit 34. The hydraulic circuit 34 engages the brake BK and controls the engagement pressure of the first clutch C1 or the second clutch C2 in the left / right driving force control mode during turning of the vehicle, and controls the determined demander. The _total torque T _CREQ is obtained. In Expression (7), k1 and k2 are constants for converting to the engagement torque of the first clutch C1 or the second clutch C2.

T _CREQ = k1 · ΔT _REQ + k2 · ΔT2 (7)

FIG. 5 is a flowchart for explaining a main part of the control operation of the electronic control unit 36, that is, left and right wheel drive torque distribution control. In FIG. 5, in step S1 (hereinafter, step is omitted) corresponding to the input torque calculation means 74, the actual throttle opening θ and the engine rotational speed NE are read from a sensor (not shown) and well-known in advance. Based on the relationship, the engine output torque TE is calculated based on the actual throttle opening θ and the engine speed NE, and the input torque T _QF (= to the front wheel differential gear device 16 which is a mechanical differential device. γ _F · T _E ) is calculated based on the engine output torque T _E and the previously stored transmission ratio γ _F of the transmission system from the engine 12 to the differential case 42 of the differential gear device 16 for the front wheels. Next, in S2 corresponding to the operating state discriminating means 76, the operating state of the front wheel differential gear device 16 is, for example, any of a plurality of preset states, and the rotational speed difference between the left and right front wheels 20l, 20r. or a straight or turning traveling state of the vehicle steering angle of the steering wheel δ is determined based on whether or not preset turning decision value or more, the drive is determined on the basis of the engine output torque T _E (power ON: Accelerated driving) or non-driving (coast: coasting) state, for example, straight driving and driving torque distribution, or straight driving and negative torque distribution Is a state where the vehicle is turning right and driving torque is being distributed, is a state turning right and is distributing negative torque, or is turning left Ah Thus, it is determined whether the driving torque is being distributed or the vehicle is turning left and negative torque is being distributed.

Subsequently, in S3 corresponding to the drive torque distribution ratio calculating means 78, the drive torque distribution to the left and right front wheels 20l and 20r is added with the differential limiting torque mechanically generated in the front wheel differential gear device 16. Approximations in which the ratios RHratio and RLHratio are selected based on the differential state determined by the above-described S2 (operating state determining means 76) from a plurality of kinds of approximate expressions stored in advance, for example, the expressions (1) to (3). Calculated using the formula. In S4 corresponding to the correction value calculation means 80, the correction value ΔT2 corresponding to the differential limiting torque mechanically generated in the front wheel differential gear device 16 is obtained from, for example, the previously stored equation (6). , The distribution ratio RHratio to the right front wheel 20r and the distribution ratio RLHratio to the left front wheel 20l calculated by S3 (drive torque distribution ratio calculation means 78), and the difference for the front wheels calculated by S1 (input torque calculation means 74). It is calculated based on the input torque T _QF to the dynamic gear device 16.

Next, in S5 corresponding to the target yaw rate calculation means 70, during the turning of the vehicle, a neutral steer between the understeer and the oversteer is set based on the steering angle δ of the steering wheel based on the relationship stored in advance. The target yaw rate r ^* is calculated. In S6 corresponding to the target left / right torque difference calculating means 72, a target yaw rate r ^* calculated by the target yaw rate calculating means 70 and an actual yaw rate r output from a yaw rate sensor (not shown ⁾ are stored based on a previously stored relationship. Based on the yaw rate deviation Δr (= r ^* −r), a target left-right torque difference ΔT ^* for eliminating the yaw rate deviation Δr is calculated.

In S7 and S8 corresponding to the left / right drive torque difference control means 82, the target left / right torque difference calculated by S6 (target left / right torque difference calculation means 72) from the control expression shown in the expression (7) stored in advance. Required engagement torque T _CREQ required for the first clutch C1 or the second clutch C2 based on ΔT ^*, that is, the required left-right torque difference ΔT _REQ and the correction value ΔT2 calculated by S4 (correction value calculation means 80). Is calculated as the control amount of the first clutch C1 or the second clutch C2, and the required engagement torque T _CREQ is output to the hydraulic circuit 34.

As described above, according to the present embodiment, the driving torque distribution ratio calculating means 78 (S3) drives the driving torque distribution ratio of the left and right front wheels 20l and 20r by the front wheel differential gear device (mechanical differential device) 16. RHratio is calculated, and the left / right driving torque difference control means 82 (S7) calculates the target left / right driving torque difference based on the driving torque distribution ratio RHratio of the left and right front wheels 20l and 20r and the target left / right driving torque difference ΔT ^*. Since the first clutch C1 and the second clutch C2 (left and right driving torque difference adjusting device) are controlled so as to obtain ΔT ^*, high-precision control for distributing the driving torque to the left and right rear wheels 30l and 30r is obtained. .

Further, according to this embodiment, (a) based on the positive / negative driving state of the front wheel differential gear device 16 and the difference in rotational speed between the left and right front wheels 20l and 20r, the front wheel differential gear device 16 An operating state discriminating means 76 (S2) for discriminating an operating state is included, and (b) a drive torque distribution ratio calculating means 78 (S3) is a differential gear device for front wheels determined by the operating state discriminating means 76. Based on a calculation formula corresponding to the operating state of 16, the drive torque distribution ratio RHratio to the left and right front wheels 20 l and 20 r by the front wheel differential gear device 16 based on the lock ratio LE of the front wheel differential gear device 16 set in advance. because There is calculated, and the driving torque distribution ratio RHratio, based on the target left-right drive torque difference [Delta] T ^*, the target left and right drive torque difference [Delta] T as ^* is obtained first clutch C1 and the second clutch C Since but controlled, high-precision control of distributing the driving torque to the left and right rear wheels 30l and 30r is obtained.

Further, according to the present embodiment, (a) the operation state determining means 76 (S2) is configured to determine whether the front wheel differential gear device 16 is in the positive drive state or the negative drive state, and the left and right front wheels 20l and It is determined whether the rotational speed difference of 20r is a left or right turning traveling state greater than a predetermined value. (B) The drive torque distribution ratio calculating means 78 (S3) is determined by the operating state determining means 76. One of the left and right front wheels 20l and 20r is calculated based on a preset lock ratio LE of the front wheel differential gear device 16 from a calculation formula corresponding to a plurality of operating states of the front wheel differential gear device 16. since it calculates the 20r torque distribution ratio RHratio of which calculates a torque distribution ratio RLHratio of the other front wheel 20l, and the drive torque distribution ratio RHratio and RLHratio, the target left-right drive torque difference [Delta] T ^* Based on, because the target left driving torque difference [Delta] T ^* as is obtained first clutch C1 and second clutch C2 is controlled, high-precision control of distributing the driving torque to the left and right rear wheels 30l and 30r is obtained It is done.

Further, according to this embodiment, the input torque T _QF to the differential torque distribution ratio RLHratio the front wheels of the other front wheel 20l gear 16 to calculate a torque distribution ratio RHratio of one front wheel 20r (a) The correction value calculating means 80 (S4) for calculating the correction value ΔT2 is included, and (b) the left / right driving torque difference control means 82 (S7) is configured to obtain the target left / right driving torque difference ΔT ^*. The control amount T _CREQ for the first clutch C1 and the second clutch C2 (the left and right driving torque difference adjusting device) is corrected by the correction value ΔT2 calculated by the correction value calculation means 80 (S4). Thus, since the first clutch C1 and the second clutch C2 are controlled, high-accuracy control for distributing the drive torque to the left and right rear wheels 30l and 30r is obtained.

Further, according to this embodiment, (a) the front wheel differential gear device 16 distributes the input torque T _QF input from the engine 12 to the left and right front wheels 20l and 20r of the vehicle. ) First clutch C1 and second clutch C2 (left / right drive torque difference adjusting device) Since the drive torque difference between the left and right rear wheels 30l and 30r of the vehicle is adjusted, the target left / right drive torque difference is determined in a four-wheel drive vehicle. High-precision control that distributes the drive torque to the left and right rear wheels 30l and 30r to obtain ΔT ^* is obtained. Further, according to the four-wheel drive vehicle of the present embodiment, the relatively small front-wheel differential gear device 16 is provided in the front portion having no space, and the relatively large driving force distribution device 26 is provided in the rear portion having a large space. There is an advantage to be provided.

Further, according to this embodiment, (a) the differential device 62 that distributes the input torque T _QF input from the engine 12 to the other left and right rear wheels 30l and 30r moving wheels, and the differential device 62 and the left and right Between a transmission 64 provided between at least one of the rear wheels 30l and 30r, and a pinion (output member) P3 of the transmission 64 and at least one of the left and right drive wheels 30l and 30r A rear wheel driving force distribution device 26 having a pair of first clutch C1 and second clutch C2 (engaging element) provided on the rear wheel, and (b) the first clutch C1 and the second clutch C2. Functions as a left / right driving torque difference adjusting device, and therefore, the target left / right driving torque difference ΔT is adjusted by adjusting the driving torque difference between the left and right rear wheels 30l and 30r using a pair of engagement elements. High-accuracy control that distributes the left and right rear wheels 30l and 30r driving torque to obtain ^* is obtained.

  As mentioned above, although one Example of this invention was described based on drawing, this invention is applied also in another aspect.

  For example, in the above-described embodiment, the example in which the driving force distribution device 26 and the like are applied to a front and rear wheel drive vehicle based on front engine front wheel drive has been described, but the present invention is not limited to this. For example, based on the rear wheel drive in which the Torsen differential gear device similar to the front wheel differential gear device 16 of the above-described embodiment is provided for the rear wheel and the driving force distribution device 26 is provided for the front wheel. It may be a front and rear wheel drive vehicle. Further, the engine 12 may be a front end or a rear end. That is, it may be a front engine front wheel drive (FF) vehicle or a front engine rear wheel drive (FR) vehicle.

  In the above-described embodiment, the differential device 62 provided in the driving force distribution device 26 may be a Torsen-type differential gear device. In such a case, a drive torque distribution ratio corresponding to the differential limit torque mechanically generated in the differential device 62 is calculated, and correction corresponding to the drive torque distribution ratio is performed in the same manner as described above. Also good. Further, when the differential device 62 provided in the driving force distribution device 26 is a Torsen-type differential gear device, the front wheel differential gear device 16 has a planetary gear type that has a relatively small differential limiting action. Even in a vehicle that is a differential device or a two-wheel drive vehicle in which the front wheels are not driven, a drive torque distribution ratio corresponding to the differential limiting torque that is mechanically generated in the differential device 62 is calculated, and the drive torque is calculated. Correction corresponding to the distribution ratio may be performed in the same manner as described above. Accordingly, it may be a two-wheel drive front wheel drive (FF) vehicle, a rear wheel drive (FR) vehicle, or the like.

  In the above-described embodiments, the drive source is an internal combustion engine such as a gasoline engine or a diesel engine. However, the drive source is not particularly limited thereto, and is composed of another drive source such as an electric motor. It doesn't matter.

  Further, in the above-described embodiment, the transmission device 64 is configured by two planetary gear devices, but the configuration of the transmission device 64 and the like includes the ring gear R1 (first rotating element RE1) or the carrier CA2 (first Any structure that can change the speed of rotation of the sun gear S3 (fourth rotating element RE4) with respect to the rotating element RE2) may be used, a structure using one or more planetary gear units, a double pinion type and a single pinion Various other types of transmissions, such as a configuration with two planetary gear devices of a type, may be used, and not only an increase in speed but also a reduction transmission.

  Further, in the above-described embodiment, the differential device 62 is constituted by a double pinion type planetary gear device, but the planetary gear comprising the first rotating element RE1, the second rotating element RE2, and the third rotating element RE3. Any device provided with a device may be used, and a single pinion type planetary gear device may be provided.

  In the above-described embodiment, the left-right relationship between the left rear wheel axle 28l, the right rear wheel axle 28r, the left rear wheel 30l of the rear wheel 30, and the right rear wheel 30r is not particularly limited, and the left and right are reversed. Can also be implemented.

  Further, in the above-described embodiment, the drive torque distribution ratio calculating means 78 distributes the drive torque to the left and right front wheels 20l and 20r in consideration of the differential limiting torque mechanically generated in the front wheel differential gear device 16. In order to determine the ratio, a plurality of kinds of approximate expressions stored in advance, for example, the expressions (1) to (3) are used, but other calculation expressions such as a more complicated expression without approximation may be used. A map may be used. In short, any relationship that takes into account the differential limiting torque that is mechanically generated in the differential gear device 16 for the front wheels may be used.

  In the above-described embodiment, the fifth rotation element RE5 is locked by the brake BK used for switching the torque movement, but the brake BK can be used in a half-engaged state.

  In the above-described embodiment, the first clutch C1, the second clutch C2, and the brake BK are engaged and operated by hydraulic pressure, but other types of clutch devices such as an electromagnetic type, a magnetic powder type, etc. It can also be implemented using a brake device.

  The above description is only an embodiment, and the present invention can be implemented in variously modified and improved forms based on the knowledge of those skilled in the art.

1 is a diagram showing a power transmission system of a front and rear wheel drive vehicle based on a front engine front wheel drive of a vehicle to which a control device for a vehicle driving force distribution device according to an embodiment of the present invention is applied. FIG. 2 is a skeleton diagram illustrating a configuration of a driving force distribution device provided on the front wheel side of the power transmission system of FIG. 1. FIG. 2 is a skeleton diagram illustrating a configuration of a driving force distribution device provided on the rear wheel side of the power transmission system of FIG. 1. It is a functional block diagram explaining the principal part of the control function of the electronic control apparatus of FIG. It is a flowchart explaining the principal part of the control action of the electronic controller of FIG.

Explanation of symbols

16: Differential gear for front wheels (mechanical differential)
26: Vehicle driving force distribution device 62: Differential device (differential unit)
64: Transmission (transmission unit)
74: input torque calculating means 76: operating state determining means 78: driving torque distribution ratio calculating means 80: correction value calculating means 82: left and right driving torque difference control means RE1: first rotating element RE2: second rotating element RE3: third Rotating element RE4: Fourth rotating element RE5: Fifth rotating element C1: First clutch (engaging element, left and right driving force difference adjusting device)
C2: Second clutch (engagement element, left / right driving force difference adjusting device)
BK: Brake

Claims (7)

A mechanical differential device that distributes the input torque input from the drive source to the left and right drive wheels, and a left and right drive torque difference adjustment device that can adjust the drive torque difference between the left and right drive wheels. A control device for a vehicle driving force distribution device for controlling the left / right driving torque difference adjusting device so as to obtain a target left / right driving torque difference,
Drive torque distribution ratio calculating means for calculating a drive torque distribution ratio of the left and right drive wheels by the mechanical differential device;
The target left-right drive torque difference is obtained based on the drive torque distribution ratio of the left and right drive wheels by the mechanical differential device calculated by the drive torque distribution ratio calculation means and the target left-right drive torque difference. And a left and right driving torque difference control means for controlling the left and right driving torque difference adjusting device as described above. An operation state determining means for determining an operation state of the mechanical differential device based on a positive / negative of a drive state by the mechanical differential device and a rotational speed difference between the left and right drive wheels;
The drive torque distribution ratio calculating means is based on a preset lock rate of the mechanical differential device from a relationship that takes into account the operating state of the mechanical differential device determined by the operating state determining means. 2. The control device for a vehicle driving force distribution device according to claim 1, wherein a drive torque distribution ratio between the left and right drive wheels is calculated by a mechanical differential device. The operating state determining means is configured to determine whether the mechanical differential is in a positive drive state or a negative drive state, and in a left or right turn traveling state in which a difference in rotational speed between the left and right drive wheels is greater than or equal to a predetermined value. It is to determine whether there is,
The drive torque distribution ratio calculating means is based on a preset lock rate of the mechanical differential device from a relationship that takes into account the operating state of the mechanical differential device determined by the operating state determining means. The control device for a vehicle driving force distribution device according to claim 2, wherein a torque distribution rate of one of the left and right drive wheels is calculated and a torque distribution rate of the other drive wheel is calculated. Correction value calculating means for calculating a correction value based on the torque distribution rate of the one drive wheel and the torque distribution rate of the other drive wheel and the input torque of the mechanical differential device;
The left-right drive torque difference control means corrects the control amount for the left-right drive torque difference adjusting device with the correction value calculated by the correction value calculation means so that a target left-right drive torque difference is obtained. 4. The control device for a vehicle driving force distribution device according to claim 3, wherein the left and right driving torque difference adjusting device is controlled by using the control device. The mechanical differential device distributes input torque input from a drive source to one of the left and right drive wheels of a front wheel and a rear wheel of a vehicle,
5. The control device for a vehicle driving force distribution device according to claim 1, wherein the left / right driving torque difference adjusting device adjusts a driving torque difference between the other left and right driving wheels of the front wheel and the rear wheel. The mechanical differential device distributes input torque input from a drive source to the left and right drive wheels of the front wheel of the vehicle,
6. The control device for a vehicle driving force distribution device according to claim 5, wherein the left / right driving torque difference adjusting device adjusts a driving torque difference between left and right driving wheels of a rear wheel of the vehicle. A differential device that distributes input torque input from the drive source to the other left and right drive wheels, an input member that is input from any one of the rotating elements of the differential device, and the left and right drive wheels A rear wheel drive comprising a transmission provided between at least one of the transmissions and a pair of engagement elements provided between an output member of the transmission and at least one of the left and right drive wheels. Including a torque distribution device,
The control device for a vehicle driving force distribution device according to claim 6, wherein the left / right driving torque difference adjusting device includes the pair of engaging elements.

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