JP2008256000A - Controller of driving force distribution device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a controller of a driving force distribution device for a vehicle which can perform high accuracy control of distributing a driving force to right/left driving wheels. <P>SOLUTION: In the driving force distribution device 26 for a vehicle which comprises a differential arrangement 42 distributing an input torque T<SB>IN</SB>from an engine (power source) 12 to right/left rear wheels 30l and 30r, and a first clutch C1 or second clutch C2 being an engagement element generating a torque difference between the right/left rear wheels 30l and 30r by suppressing a differential action of the differential arrangement 42, and in an electronic controller 36 controlling the first clutch C1 or the second clutch C2 so that a preliminarily obtained target right/left torque difference ΔT<SP>*</SP>might be obtained from a mechanically differential restraint property (bias ratio B) of the differential arrangement 42 set in advance, a controlled variable T<SB>CREQ</SB>to the first clutch C1 or the second clutch C2 is fixed. Therefore, the high accuracy control of distributing the driving torque to the right/left rear wheels 30l and 30r is possible. <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 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 driving force distribution device as described above, the driving force is distributed to the left and right drive wheels by the differential mechanism, and the slip engagement of the engagement element that generates a torque difference between the left and right drive wheels. Is used to speed up or decelerate one of the drive wheels from the other to obtain the required left-right torque difference, that is, the target left-right torque difference. However, in the control device of the conventional vehicle driving force distribution device, sufficient control accuracy cannot always be obtained, and there are cases where it is not possible to sufficiently obtain the target left-right torque difference stably.

  As a result of various studies conducted by the present inventors against the background described above, for example, in a mechanical differential device such as a planetary gear device, a certain amount of differential limiting torque is necessarily present for mechanical reasons. As a premise, when the control amount calculated to control the engagement element so as to obtain the target left-right torque difference is controlled, the above-mentioned mechanical differential limit torque is added to the differential limit torque based on the control amount. In consideration of this, the present inventors have found that the control accuracy of the distribution control can be suitably obtained for the left and right driving wheels of the driving force. 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.

  The gist of the invention according to claim 1 for achieving such an object is to provide a differential device that distributes input torque input from a drive source to left and right drive wheels, and a torque difference between the left and right drive wheels. A vehicle driving force distribution device including an engagement element to be generated is a control device for a vehicle driving force distribution device that controls the engagement element so as to obtain a target left-right torque difference obtained in advance. The control amount to the engaging element is determined based on the set mechanical differential limiting characteristic of the differential device.

  According to the first aspect of the present invention, since the control amount to the engagement element is determined based on the mechanical differential limiting characteristic of the differential device set in advance, the vehicle driving force distribution device Since the control amount is determined after taking into account the mechanical differential limiting torque that is inevitably generated due to the mechanism of the differential gear provided in the drive, the drive force is transferred to the left and right drive wheels. A control device for a vehicle driving force distribution device capable of high-precision control of distribution can be obtained.

  In the control device for a vehicle driving force distribution device according to a second aspect of the present invention, a control amount determination for determining a control amount for the engagement element is performed using a control equation having the target left-right torque difference and the input torque as variables. Means include. In this way, a control amount for controlling the engagement element can be obtained with high accuracy so as to obtain a target left-right torque difference obtained in advance.

  In the control device for a vehicle driving force distribution device according to a third aspect of the invention, the control amount determination means includes a torque difference between left and right drive wheels indicated by the target left-right torque difference, and a mechanical differential of the differential device. When the torque distribution tendency in the left and right drive wheels is different from the torque difference between the left and right drive wheels caused by the limiting characteristics, the left and right drive wheels indicated by the target left and right torque difference are compared to the same case. The control amount is determined so as to increase the torque difference. In this way, the target left-right torque obtained in advance regardless of the presence of the mechanical differential limiting torque inevitably generated from the mechanism of the differential gear provided in the vehicle driving force distribution device. A control amount for controlling the engagement element so as to obtain a difference is obtained with high accuracy.

  In the control device for a vehicle driving force distribution device according to a fourth aspect of the invention, the control amount determination means includes a torque difference between left and right drive wheels indicated by the target left-right torque difference, and a mechanical differential of the differential device. When the torque distribution tendency between the left and right drive wheels differs from the torque difference between the left and right drive wheels generated by the limiting characteristics, the input torque input from the drive source is larger when compared with the smaller case. The control amount is determined so that the torque difference between the left and right drive wheels indicated by the target left-right torque difference is large. The mechanical differential limiting torque has a characteristic that changes in relation to the input torque input from the drive source. By doing so, the target left and right target values obtained in advance can be obtained regardless of the input torque input from the drive source. A control amount for controlling the engagement element so as to obtain a torque difference is obtained with high accuracy.

  In the control device for a vehicle driving force distribution device according to the fifth aspect of the present invention, (a) the first differential element to which the input torque is input, the left driving wheel and the right driving wheel are respectively connected to the differential device. And (b) a speed change portion that shifts the rotation transmitted to the first rotation element and transmits the rotation to the fourth rotation element, and (c) As the engagement element, a first friction engagement device that transmits torque transmitted to the fourth rotation element to the second rotation element, and torque transmitted to the fourth rotation element to the third rotation element. (D) a control amount for controlling a torque transmission capacity generated by the first friction engagement device and the second friction engagement device is determined by the control amount determination means. It is characterized by that. If it does in this way, the differential provided with the 1st thru / or the 3rd rotation element, the transmission part which transmits the power transmitted to the 1st rotation element to the 4th rotation element, and it was transmitted to the 4th rotation element A driving force distribution device including a first friction engagement device and a second friction engagement device that transmit torque to the second rotation element and the third rotation element is based on the control amount determined by the control amount determination means. To distribute torque to the left and right drive wheels.

  In the control device for a vehicle driving force distribution device according to a sixth aspect of the invention, the differential device transmits the torque of the first friction engagement device or the second friction engagement device from the input torque input from the drive source. The torque distribution is performed with the value excluding the capacity. In this way, the accuracy of the control amount for controlling the engagement element so as to obtain the target left-right torque difference obtained in advance is improved.

In the control device for a vehicle driving force distribution device according to claim 7, the ratio of the torque to one of the left and right drive wheels indicating the mechanical differential limiting characteristic of the differential device is set to B, and the speed change When the speed ratio of the device is ρ, the input torque input from the drive source is T _IN , and the target left-right torque difference is ΔT _REQ , the control amount determining means is the first friction engagement device or A torque T _CREQ generated in the second friction engagement device is calculated as the control amount. In this way, a case-to-shaft type of torque is moved from the first rotating element (eg case) to the second rotating element (eg left drive wheel axle) or the third rotating element (eg left drive wheel axle). In the driving force distribution device, it is possible to easily obtain a control amount for controlling the engagement element so as to obtain a target left-right torque difference ΔT _REQ obtained in advance.

_{T CREQ = [(B-1} ) T IN + (1 + B) ΔT REQ] / (1 + B-ρ + ρ · B)

  In the control device for a vehicle driving force distribution device according to an eighth aspect of the present invention, (a) the first differential element to which the input torque is input, the left driving wheel and the right driving wheel are respectively connected to the differential device. (B) accelerating the rotation transmitted to the second rotation element, transmitting it to the fourth rotation element, and decelerating the fifth rotation element. And (c) a first friction engagement device for transmitting torque transmitted to the fifth rotating element to the third rotating element as the engaging element, and a fourth rotating element And a second friction engagement device for transmitting the torque transmitted to the third rotating element, and (d) controlling a torque transmission capacity generated by the first friction engagement device and the second friction engagement device. The control amount is determined by the control amount determination means. If it does in this way, the differential provided with the 1st thru / or the 3rd rotation element, the transmission part which transmits the power transmitted to the 2nd rotation element to the 4th rotation element and the 5th rotation element, and the 4th rotation A driving force distribution device including a first friction engagement device and a second friction engagement device that transmit the torque transmitted to the element and the fifth rotation element to the third rotation element is determined by the control amount determination means. The torque to the left and right drive wheels is distributed based on the control amount.

In the control device for a vehicle driving force distribution device according to the ninth aspect of the invention, the control amount determining means is the other of the torque to one of the left and right drive wheels indicating the mechanical differential limiting characteristic of the differential device. , The speed ratio of the transmission is ρ, the input torque input from the drive source is T _IN , and the target left-right torque difference is ΔT _REQ , the control amount determining means is A torque T _CREQ generated in the first friction engagement device or the second friction engagement device is calculated as the control amount. In this way, in a shaft-to-shaft type driving force distribution device in which torque is moved by increasing or decreasing rotation from the second rotating element (for example, the case) to the third rotating element (for example, the axle of the right drive wheel). A control amount for controlling the engagement element can be easily obtained so as to obtain the target left-right torque difference ΔT _REQ obtained in advance.

_{T CREQ = [(1-B} ) / (B + 1)] · T IN + (1-ρ) · ΔT REQ]

  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 driving force distribution device 26 and the propeller shaft 24. Are arranged so as to be orthogonal to each other. 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 electronic control unit 36 is a so-called microcomputer that 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. For example, a clutch C1, which is a hydraulic friction engagement device (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 C2 and the brake BK, left and right wheel torque difference control, differential restriction control, and the like are executed. The power 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 intake / exhaust pipe of the engine 12. Are provided with a throttle sensor for detecting the actual opening of a throttle valve (not shown) provided in the engine, an engine rotational speed sensor for detecting the actual rotational speed of the engine 12, a front-rear G sensor, and the like. A signal representing the vehicle speed, a signal representing the shift stage, a signal representing the throttle opening, a signal representing the engine rotational speed, a signal representing the longitudinal acceleration, and the like are supplied to the electronic control unit 36.

  FIG. 2 is a skeleton diagram illustrating the configuration of the driving force distribution device 26. As shown in FIG. 2, the driving force distribution device 26 includes a bevel gear 38 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 40 meshing with the driving force 38. The driving force distribution device 26 includes a differential device (differential mechanism) 42 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 42. Adjacent to the rear wheel axles 28l and 28r and the output of the transmission 44 is selectively sent to a pair of rear axles 28l and 28r which are output shafts of the differential device 42. A first clutch C1 and a second clutch C2 for transmission are provided. The differential device 42 of this embodiment corresponds to the differential portion of the driving force distribution device 26, the transmission device 44 corresponds to the transmission portion of the driving force distribution device 26, and the first clutch C1 and the second clutch C2 are This corresponds to an engagement element for generating a torque difference between the left and right rear wheels 30l and 30r.

  The differential device 42 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 P 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 P, and the gear ratio ρ is (= number of teeth of the sun gear S1 / 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 46 inside the case 46 of the differential device 42, and the rotation of the propeller shaft 24 is reduced by the bevel gears 38 and 40 and transmitted. That is, power from the engine 12 that is a driving force 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. Note that the second rotation element RE2 and the third rotation element RE3 can be replaced, and the following description is the same.

  The transmission 44 has a small-diameter pinion P2 meshed with the large-diameter sun gear S2 connected to the case 46, a small-diameter sun gear S3 corresponding to the fourth rotating element RE4, and meshed with the small-diameter sun gear S3 and larger in diameter than the small-diameter pinion P2. A large-diameter pinion P3 concentrically and integrally connected to the small-diameter pinion P2, a small-diameter pinion P2 and a large-diameter pinion P3 that are integrally connected to each other, and a carrier CA2 that rotatably and revolveably supports the A brake BK is provided between the carrier CA2 and a non-rotating member 45 such as a housing and selectively disables the carrier CA2 to rotate. It operates as a speed increasing transmission that transmits to the sun gear S3. The carrier CA2 corresponds to the fifth rotating element RE5, and the small-diameter pinion P2 functions as an input member of the transmission 44, and the large-diameter pinion P3 functions as an output member of the transmission 44.

  A first clutch C1 and a second clutch C2 that selectively connect the small diameter sun gear S3 and the left rear wheel axle 28l and between the small diameter sun gear S3 and the right rear wheel axle 28r are provided, respectively. ing. The transmission 44 and the first clutch C1 increase the rotation of the case 46 and transmit it to the left rear wheel axle 28l. The transmission 44 and the second clutch C2 increase the rotation of the case 46 and increase the rotation of the right rear wheel. Since it is transmitted to the axle 28r, the driving force distribution device 26 has a case-to-shaft type driving force distribution function.

  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 46 of the differential device 42 through the automatic transmission 14, the central differential gear device 22, the propeller shaft 24, and the like. Since the ring gear R1 of the differential device 42 is provided integrally with the case 46, all or part of the driving torque T _IN (Nm) input from the propeller shaft 24 to the ring gear R1 and the case 46 is the differential device. 42.

When the brake BK, the first clutch C1, and the second clutch C2 are in the disengaged state, the transmission 44 is in the idling state (non-transmission state) and only the differential device 42 functions. all of the drive torque T _iN input to the 46 is transmitted to the differential device 42, 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. For this reason, during straight running, the differential device 42 is rotated integrally, 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 44 functions as a speed increasing transmission that increases the speed Ns2 (rpm) of the case 46, 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 rotation of the carrier CA2 of the transmission 44 is locked, and the rotation speed Ns3 (rpm) of the sun gear S3 that is the fourth rotation element RE4 is in the same rotation direction as the rotation speed Ns2 of the sun gear S2. The speed is increased. As the second clutch C2 is slip-engaged, the rotation of the sun gear S3, which is the fourth rotation element RE4, is transmitted to the right rear wheel 30r. Here, since the rotational speed Ns3 of the sun gear S3 as the fourth rotational element RE4 is increased in the same rotational direction, the torque of the right rear wheel 30r is increased by the slip engagement of the second clutch C2, and the left The torque of the rear wheel 30l is relatively reduced. Further, since the rotational speed Nr of the right rear wheel 30r is increased by the slip engagement of the second clutch C2, the rotational speed Nl of the left rear wheel 30l is decelerated by the differential device 42.

  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 44 functions as a speed increasing transmission that increases the speed Ns2 of the case 46, 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 44 is locked, and the rotation speed Ns3 of the sun gear S3 that is the fourth rotation element RE4 is increased in the same rotation direction as the rotation speed Ns2 of the sun gear S2. . As the first clutch C1 is slip-engaged, the rotation of the sun gear S3 as the fourth rotation element RE4 is transmitted to the carrier CA1 as the second rotation element RE2. Here, since the rotational speed Ns3 of the sun gear S3 as the fourth rotational element RE4 is increased in the same rotational direction, the torque of the left rear wheel 30l is increased by the slip engagement of the first clutch C1, and the right The torque of the rear wheel 30r 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 42.

Speed increasing gear ratio of the transmission 44 (Ns3 / Ns2) the [rho (number greater than 1), the transmission torque of the first clutch C1 or second clutch C2 _{T CL} or _{T CR} (Nm), the differential device 42 Assuming that the input torque to T _D (Nm) is, when the vehicle is turning, the input torque T _D to the differential device 42 is expressed by the following equation (1) during a left turn, for example. Become. That is, part of the input torque T _IN input from the propeller shaft 24 to the casing 46 is transmitted to the differential device 42.

T _D = T _IN −ρ · T _CR (1)

Here, since the differential device 42 is mechanically configured by a planetary gear device including a sun gear S1, a ring gear R1, and a carrier CA1 that rotatably supports the pinion P1 engaged therewith, the left rear wheel 30l (second rotation) Carrier CA1) which is element RE2 and right rear wheel 30r (sun gear S1 which is first rotation element RE1) When torque is distributed while allowing differential, a certain amount of differential limiting torque is generated due to the mechanism. Inevitable. Such a mechanical differential limiting characteristic of the differential device 42 is expressed by a ratio of one torque to the other torque of the left rear wheel 30l and the right rear wheel 30r, that is, a bias ratio B. This bias ratio B is a numerical value larger than 1 and indicates the strength of the mechanical differential limiting characteristic (LSD characteristic). Generally, torque is moved from the driving wheel having the higher rotational speed of the left rear wheel 30l and the right rear wheel 30r to the driving wheel having the lower rotation speed. This indicates that the torque of the driving wheel is 1.5 times that of the driving wheel on the faster side. Thus, the torque distribution to the left rear wheel 30l and the right rear wheel 30r by the differential device 42 is dependent on the bias ratio B, the torque T _DL which is distributed to the left rear wheel _30l, and the right rear wheel 30r For example, in the left turn power-on running (left wheel speed <right wheel speed, and T _D > 0), the distributed torque T _DR is expressed by the following equations (2) and (3).

T _DL = [B / (B + 1)] · T _D (2)
T _DR = [1 / (B + 1)] T _D (3)

Then, in consideration of the amount of torque movement by the first clutch C1 and the second clutch C2 that are activated for driving force distribution during vehicle turning, the shaft torque _TL of the left rear wheel 30l and the shaft torque of the right rear wheel 30r T _R is, for example, in the left turning power on running, and those shown in the following equation (4) and (5). When the left-right torque difference ΔT is defined as (axial torque T _R of the right rear wheel 30r) − (axial torque T _L of the left rear wheel 30l), the left-right torque difference ΔT is expressed by (Equation 6).

T _L = T _DL = [B / (B + 1)] ・ T _D
= [B / (B + 1 )] (T IN -ρ · T CR) ··· (4)
T _R = T _DR + T _CR = [1 / (B + 1)] ・ T _D + T _CR
= [1 / (B + 1 )] (T IN -ρ · T CR) + T CR ··· (5)
ΔT = T _R −T _L = [1 / (B + 1)] [(1-B) T _IN
+ (1 + B−ρ + ρ · B) · T _CR ] (6)

FIG. 3 shows the sum of the left and right torques (= the torque of the outer turning wheel + the torque of the inner turning wheel) that is affected by the mechanical differential limiting characteristic (LSD characteristic) of the differential device 42 during the vehicle turning. left and right torque difference [Delta] T - relationship between (= torque of the turning outer wheel turning inner torque), i.e. if the left and right torque sum ≒ T _iN, is a graph showing the relation shown in equation (6). In FIG. 3, the broken line L ₀ indicates that the torque movement amount is zero, the broken line L ₁ indicates that the torque movement amount to the right rear wheel 30 r by the second clutch C 2 is a predetermined value, and the broken line L ₂ indicates the second clutch C 2. When the torque movement amount to the right rear wheel 30r due to is a larger value, the broken line L- ₁ indicates the case where the torque movement force to the left rear wheel 30l by the first clutch C1 is a predetermined value. As indicated by these broken lines L ₀ , L ₁ , L ₂ , L ₋₁ , even if the torque control amount is the same, the mechanical differential limiting characteristic is increased as the input torque T _IN, that is, the left and right torque wheels increase. The left-right torque difference (inner / outer ring torque difference) changes depending on the differential limit (bias torque) that is derived. Further, the break points of the broken lines L ₀ , L ₁ , L ₂ , L ₋₁ move according to the change of the torque control amount. From such a fact, in order to obtain the target left-right torque difference accurately, for example, in the control of performing torque movement by the first clutch C1 and the second clutch C2 in order to obtain the target left-right torque difference, correction of the bias torque is required. Necessary. In the control of the present embodiment described below, this is taken into consideration, and the control amount to the first clutch C1 and the second clutch C2 (engagement element) is calculated based on the mechanical differential limiting characteristic of the differential device 42. It has come to be.

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 engine output torque calculation means 50 calculates the engine output torque TE based on the actual throttle opening θ and the engine rotational speed NE from the relationship stored in advance. Input torque calculating means 52, for example, a torque ratio t, the speed ratio gamma ₁₄ of the automatic transmission 14 of the torque converter 13 from a pre-stored relationship shown in equation _(7), the gear ratio of the central differential gear device 22 gamma ₂₂ , on the basis of the engine output torque TE calculated by the engine output torque calculating unit 50 calculates the input torque T _iN is input from the propeller shaft 24 to the case 46.

T _IN = t · γ ₁₄ · γ ₂₂ · TE (7)

The target yaw rate calculating means 56 calculates 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 a prestored relationship during turning of the vehicle. . The target left-right torque difference calculating means 58 has a yaw rate deviation Δr (= r ⁾ between a target yaw rate r ^* calculated by the target yaw rate calculating means 56 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.

In the left / right driving force control mode during turning of the vehicle, the control amount determining means 60 calculates the actual input torque calculated by the input torque calculating means 52 from the control expression shown in the following equation (8) stored in advance as T _iN, and, based on the target lateral torque difference [Delta] T ^* that demand lateral torque difference [Delta] T _REQ has been calculated by the target lateral torque difference calculation means 58, required engagement torque T required for the first clutch C1 or second clutch C2 _CREQ is calculated as the control amount of the first clutch C1 or the second clutch C2. 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. The following equation (8) is obtained by arranging ΔT in the above equation (6) as ΔT _REQ .

T _CREQ = [(B−1) T _IN + (1 + B) ΔT _REQ ]
/ (1 + B-ρ + ρ ・ B) (8)
_{T CREQ = f (T IN)} + g (ΔT REQ) ··· (9)

In the above equation (8), include a first term which is proportional to the input torque T _IN is inputted to the casing 46, and a second term which is proportional to the required lateral torque difference [Delta] T _REQ of the first clutch C1 or second clutch C2 Since the driving torque T _IN of the first term and the required left-right torque difference ΔT _REQ of the second term are respectively multiplied by constant coefficients including the bias ratio B and the speed increasing gear ratio ρ, the equation (9) As shown in FIG. 5, the first term that is the function f (T _IN ) of the input torque T _IN and the second term that is the function g (ΔT _REQ ) of the required left-right torque difference ΔT _REQ are simplified and shown. be able to. For example, in the time of left turning power on running, the input torque T _D (= T _IN of the torque distribution to the left rear wheel 30l based on mechanical differential limiting characteristics of the differential device 42 (LSD action) is the differential 42 - ρ · T _CR ), that is, depending on a value (= T _IN −ρ · T _CR ) obtained by removing the torque transmitted from the first clutch C 1 or the second clutch C 2 from the input torque T _IN to the driving force distribution device 26. Therefore, a control amount for canceling this is added (added) by the second term, that is, the correction term.

Therefore, the control amount determining means 60, (8) as shown in the formula, and the torque difference between the left and right rear wheels 30l and 30r shown target lateral torque difference [Delta] T * That demand lateral torque difference [Delta] T _REQ is in bias ratio B The torque distribution tendency (torque moving direction) in the left and right rear wheels 30l and 30r is different from the torque difference between the left and right rear wheels 30l and 30r generated by the mechanical differential limiting characteristic of the differential device 42 shown. In this case, compared with the same case, the control amount, that is, the required engagement torque T _CREQ is set so that the torque difference between the left and right rear wheels _{30l and 30r} indicated by the target left-right torque difference ΔT ^*, that is, the required left-right torque difference ΔT _REQ becomes larger. To decide.

In addition, the control amount determining means 60, as shown in the equation (8), uses the target left-right torque difference ΔT ^*, that is, the torque difference between the left and right rear wheels 30l and 30r indicated by the requested left-right torque difference ΔT _REQ, and the bias ratio B. If the torque distribution tendency in the left and right rear wheels 30l and 30r is different from the torque difference between the left and right rear wheels 30l and 30r generated by the mechanical differential limiting characteristic of the differential device 42 shown, the engine 12 When the input torque T _IN input to the driving force distribution device 26 is large, the torque difference between the left and right rear wheels 30l and 30r indicated by ΔT ^*, that is, the requested left-right torque difference ΔT _REQ is larger than when the input torque T _IN is small. Thus, the control amount, that is, the required engagement torque T _CREQ is determined.

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 engine output torque calculating means 50, the actual throttle opening θ and the engine rotational speed NE are read from a sensor (not shown) and well-known in advance. From the stored relationship, the engine output torque TE is calculated based on the actual throttle opening θ and the engine speed NE. Next, in S2 corresponding to the input torque calculating means 52, the torque ratio t of the torque converter 13, the speed ratio γ ₁₄ of the automatic transmission ₁₄ , and the central differential gear unit 22 are calculated from the relationship stored in advance as shown in Expression (7). Based on the engine output torque TE calculated by the speed ratio γ ₂₂ and S1, the input torque T _IN input from the propeller shaft 24 to the case 46 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. Further, the transmission gear ratio γ ₂₂ of the central differential gear device 22 is a constant value and is stored in advance.

Next, in S3 corresponding to the target yaw rate calculation means 56, a neutral steer between the understeer and the oversteer is made based on the steering angle δ of the steering wheel based on the steering angle δ of the steering wheel based on the relationship stored in advance while the vehicle is turning. A target yaw rate r ^* is calculated. In S4 corresponding to the target left-right torque difference calculating means 58, a target yaw rate r ^* calculated by the target yaw rate calculating means 56 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.

Subsequently, in S5 corresponding to the control amount determining means 60, in the left and right driving force control mode during turning of the vehicle, the actual input torque calculated in S2 from the control expression shown in Expression (8) stored in advance. the _{T iN,} and, based on the target lateral torque difference [Delta] T ^* that demand lateral torque difference [Delta] T _REQ calculated by S4, required engagement torque _{T CREQ} required of the first clutch C1 or second clutch C2 is first It is calculated as the control amount of the clutch C1 or the second clutch C2.

In S 6 corresponding to the output means, the required engagement torque T _CREQ that is the control amount is output to the hydraulic circuit 34. As a result, in the left / right driving force control mode during turning of the vehicle, the brake BK is engaged, and the engagement pressure of the first clutch C1 or the second clutch C2 is controlled to determine the above. The required engagement torque T _CREQ can be obtained.

As described above, according to this embodiment, a differential device 42 for distributing an input torque T _IN is inputted from an engine (drive source) 12 to the left and right rear wheels (drive wheels) 30l and 30r, the differential In the vehicle driving force distribution device 26 including the first clutch C1 or the second clutch C2 which is an engagement element that limits the differential action of the device 42 and generates a torque difference between the left and right rear wheels 30l and 30r, In the electronic control unit 36 that controls the first clutch C1 or the second clutch C2 so as to obtain the desired target left-right torque difference ΔT ^*, a mechanical differential limiting characteristic (bias bias) of the preset differential unit 42 is set. since the first control amount T _CREQ to the clutch C1 or the second clutch C2 is determined based on the ratio B), derived from the mechanism of the differential device 42 provided in the driving force distribution device 26 Since the control amount T _CREQ is to be determined in terms of mechanical differential limiting torque inevitably generate is consideration Te, high-precision control for distributing the drive torque to the left and right rear wheels 30l and 30r are It becomes possible.

Further, according to this embodiment, controlled with the target lateral torque difference [Delta] T ^* and the input torque T _IN as variables (8), the control amount to the first clutch C1 or second clutch C2 is engaged element Since the control amount determining means 60 (S5) for determining T _CREQ is _provided , the control amount for controlling the first clutch C1 or the second clutch C2 so as to obtain the target left-right torque difference ΔT ^* obtained in advance. _TCREQ can be obtained with high accuracy.

Further, according to the present embodiment, the control amount determination means 60 (S5) causes the torque difference between the left and right rear wheels 30l and 30r indicated by the target left-right torque difference ΔT ^* and the differential device 42 indicated by the bias ratio B. When the torque distribution tendency in the left and right rear wheels 30l and 30r is different from the torque difference between the left and right rear wheels 30l and 30r generated by the mechanical differential limiting characteristic, the target left and right are compared with the same case. The control amount T _CREQ is determined so that the torque difference between the left and right rear wheels _{30l and 30r} indicated by the torque difference ΔT ^* becomes large. For this reason, the first clutch C1 is obtained so that the target left-right torque difference ΔT ^* obtained in advance can be obtained regardless of the presence of the mechanical differential limiting torque that is inevitably generated due to the mechanism of the differential device 42. _{Alternatively,} the control amount T _CREQ for controlling the second clutch C2 can be obtained with high accuracy.

Further, according to the present embodiment, the control amount determination means 60 (S5) causes the torque difference between the left and right rear wheels 30l and 30r indicated by the target left-right torque difference ΔT ^* and the differential device 42 indicated by the bias ratio B. When the torque distribution tendency in the left and right rear wheels 30l and 30r is different from the torque difference between the left and right rear wheels 30l and 30r generated due to the mechanical differential limiting characteristic, it is input from the engine (drive source) 12. When the input torque T _IN is large, the control amount T _CREQ is determined so that the torque difference between the left and right drive wheels indicated by the target left-right torque difference ΔT ^* is greater than when the input torque T _IN is small. Although mechanical differential limiting torque of the differential device 42 has a characteristic that varies in relation to the input torque T _IN is inputted from the engine 12, in this manner, the input torque T _IN is inputted from the engine 12 Regardless, the control amount T _CREQ for controlling the first clutch C1 or the second clutch C2 is obtained with high accuracy so that the target left-right torque difference ΔT ^* obtained in advance can be obtained.

Further, according to this embodiment, (a) the differential device 42, a ring gear R1 (first rotary element RE1) all or part of the input torque _{T IN} is input, the left and right rear wheels 30l and 30r Each has a carrier CA1 (second rotating element RE2) and a sun gear S1 (third rotating element RE3) connected to each other, and (b) its ring gear R1 (the torque T _D (= T transmitted to the first rotating element). _IN −ρ · T _CR ) and a transmission (transmission unit) 44 for transmitting the transmission to the sun gear S3 (fourth rotation element RE4). (C) Torque transmitted to the sun gear S3 as an engagement element A first clutch (first friction engagement device) C1 for transmitting the torque to the carrier CA1, and a second clutch (second friction engagement device) C2 for transmitting the torque transmitted to the sun gear S3 to the sun gear S1. (d) Control amount _{T CREQ} for controlling the torque transmission capacity to be generated in the first clutch C1 and second clutch C2 is determined by the control amount determining means 60 (S5). Accordingly, the first rotary element RE1 through the third rotary element A differential device 42 having RE3, a transmission (transmission unit) 44 that transmits power transmitted to the first rotating element to the fourth rotating element RE4, and a torque transmitted to the fourth rotating element RE4 to the second The driving force distribution device 26 including the first clutch C1 and the second clutch C2 that transmit to the rotation element RE2 and the third rotation element RE3 is based on the control amount T _CREQ determined by the control amount determination means 60 (S5). To distribute torque to the left and right rear wheels 30l and 30r.

Further, according to this embodiment, the differential device 42, the first clutch from the input torque T _IN is inputted from the engine 12 (the first frictional engagement device) C1 or the second clutch (second friction engagement device) Since the value T _D (= T _IN −ρ · T _CR ) excluding the torque transmission capacity of C 2 is torque-distributed, the first clutch C 1 or the second clutch C 2 The accuracy of the control amount T _CREQ for controlling the clutch C2 is increased.

Further, according to the present embodiment, the control amount determining means 60 (S5) applies the first clutch (first friction engagement device) C1 or the second clutch (second friction engagement device) C2 according to the equation (8). the torque T _CREQ generating, so calculated as a control quantity, be easily controlled amount T _CREQ for controlling the first clutch C1 or second clutch C2 as previously obtained target lateral torque difference [Delta] T ^* is obtained can get.

  Next, another embodiment of the present invention will be described. In the following description, parts common to those in the above-described embodiment are denoted by the same reference numerals and description thereof is omitted.

  FIG. 6 is a skeleton diagram showing a configuration of a driving force distribution device 66 having a shaft-to-shaft type driving force distribution function. The drive force distribution device 66 includes a differential device (differential mechanism) 42 for distributing drive torque to the left and right rear wheels 30l and 30r via a pair of rear wheel axles 28l and 28r, and the differential device. 42, a transmission 68 disposed adjacent to the rear wheel axles 28l, 28r, and a pair of rear wheel axles 28l, 28r, which are output shafts of the differential device 42. A first clutch C1 and a second clutch C2 that selectively transmit to The differential device 42 of the present embodiment is configured in the same manner as in the above-described embodiment, but the configuration of the transmission 68 and the arrangement of the first clutch C1 and the second clutch C2 are different from the above-described embodiment.

  The transmission 68 outputs the rotation of the rear wheel axle 28l at an increased speed and a reduced speed, and selectively transmits it to the right rear wheel axle 28r so as to be integrally connected to each other. A pinion P3, and a carrier CA2 that supports the fourth pinion P4 in a rotatable manner. The second pinion P2 is meshed with a second sun gear S2 connected to the left rear wheel axle 28l via a carrier CA1 functioning as a second rotating element RE2. The third pinion P3 has a larger diameter than the second pinion P2, and meshes with the third sun gear S3 (fourth rotating element RE4) that is selectively connected to the right rear wheel axle 28r via the second clutch C2. Has been. The fourth pinion P4 has a smaller diameter than the second pinion P2, and meshes with a fourth sun gear S4 that is selectively connected to the right rear wheel axle 28r via the first clutch C1. The carrier CA2 corresponds to the sixth rotating element RE6, the second pinion P2 is an input member of the transmission 68, the third pinion P3 is an acceleration output member of the transmission 68, and the fourth pinion P4 is a shift. It is made to function as a deceleration output member of the device 68.

  Between the third sun gear S3 and the right rear wheel axle 28r and between the fourth sun gear S4 and the right rear wheel axle 28r, there are a first clutch C1 and a second clutch C2 that selectively connect them, respectively. Is provided. The transmission 68 and the first clutch C1 increase the rotation of the left rear wheel axle 28l and transmit it to the right rear wheel axle 28r, and the transmission 68 and the second clutch C2 decelerate the rotation of the left rear wheel axle 28l. Thus, the driving force distribution device 66 has a shaft-to-shaft type driving force distribution function.

The distribution of the driving force to the left and right rear wheels 30l and 30r by the driving force distribution device 66 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 46 of the differential device 42 through the automatic transmission 14, the central differential gear device 22, the propeller shaft 24, and the like. Since the ring gear R1 of the differential device 42 is provided integrally with the case 46, the entire drive torque T _IN (Nm) input from the propeller shaft 24 to the ring gear R1 and the case 46 is transmitted to the differential device 42. Is done.

  In the state where the first clutch C1 and the second clutch C2 are in the disengaged state, the driving force distribution device 66 functions as a normal open differential in the same manner as the driving force distribution device 26 of the above-described embodiment. is there. However, as will be described in detail below, the driving force distribution control executed while the vehicle is turning is different.

  In the driving force distribution control executed while the vehicle is turning, the transmission 68 increases the rotational speed Ns2 (rpm) of the second sun gear S2 connected to the left rear wheel axle 28l and the carrier CA1 to the sun gear S3. It is made to function as a speed increasing transmission for transmission or a speed reduction transmission for decelerating and transmitting the rotation speed Ns2 (rpm) of the second sun gear S2 to the fourth sun gear S4.

  For example, during left turn, the torque of the right rear wheel 30r is increased in order to suppress understeer of the vehicle. In this case, the second clutch C2 is slip-engaged and the first clutch C1 is released. As the second clutch C2 is slip-engaged, the rotation of the second sun gear S2 is accelerated by the transmission 68 and transmitted to the third sun gear S3, which is the fourth rotation element RE4. Thus, since the rotation speed Ns3 of the third sun gear S3 that is the fourth rotation element RE4 is increased in the same rotation direction, the torque of the right rear wheel 30r is relatively increased by the slip engagement of the second clutch C2. To increase the torque of the left rear wheel 30l relatively. Further, since the rotational speed Nr of the right rear wheel 30r is increased by the slip engagement of the second clutch C2, the rotational speed Nl of the left rear wheel 30l is decelerated by the differential device 42.

  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 first clutch C1 is slip-engaged and the second clutch C2 is released. As the first clutch C1 is slip-engaged, the rotation of the second sun gear S2 is decelerated by the transmission 68 and transmitted to the fourth sun gear S4, which is the fifth rotation element RE5. Thus, since the rotation speed Ns4 of the fourth sun gear S4 that is the fifth rotation element RE5 is decelerated in the same rotation direction, the torque of the right rear wheel 30r is relatively reduced by the slip engagement of the first clutch C1. The torque of the left rear wheel 30l is relatively increased. Further, since the rotational speed Nr of the right rear wheel 30r is decelerated by the slip engagement of the first clutch C1, the differential device 42 increases the rotational speed Nl of the left rear wheel 30l.

In transmission 68 of this embodiment, since the carrier CA1 is connected to the second sun gear S2, the input torque T _D of the transmission 68 which is input to the ring gear R1, as shown in the following equation (10) is the same as the input torque _{T iN} input from the propeller shaft 24 to the case 46.

T _D = T _IN (10)

As described above, the differential device 42 is mechanically configured by the planetary gear device including the sun gear S1, the ring gear R1, and the carrier CA1 that rotatably supports the pinion P1 that meshes with the sun gear S1, so The carrier CA1) which is the two-rotation element RE2 and the right rear wheel 30r (the sun gear S1 which is the third rotation element RE3) When torque is distributed while allowing the differential, there is a mechanical differential limiting characteristic derived from that mechanism The ratio of the other torque to the torque of one of the left rear wheel 30l and the right rear wheel 30r, that is, the bias ratio B is expressed. Thus, the torque distribution to the left rear wheel 30l and the right rear wheel 30r by the differential device 42 is dependent on the bias ratio B distribution, torque T _DL which is distributed to the left rear wheel _30l, and the right rear wheel 30r For example, in the left turn power-on running (left wheel speed <right wheel speed, and T _D > 0), the torque T _DR to be applied is expressed by the following equations (11) and (12).

_{T DL = [B / (B} + 1)] · T D -ρ · T CR ··· (11)
T _DR = [1 / (B + 1)] T _D (12)

Then, in consideration of the amount of torque movement by the first clutch C1 and the second clutch C2 that are activated for driving force distribution during vehicle turning, the shaft torque _TL of the left rear wheel 30l and the shaft torque of the right rear wheel 30r T _R is, for example, in the left turning power on running, and those shown in the following equation (13) and (14). Further, when the left-right torque difference ΔT is defined as (axial torque T _R of the right rear wheel 30r) − (axial torque T _L of the left rear wheel 30l), the left-right torque difference ΔT is expressed by Expression (15).

T _L = T _DL = [B / (B + 1)] ・ T _D
= [B / (B + 1)] T _IN -ρ · T _CR (13)
T _R = T _DR + T _CR = [1 / (B + 1)] ・ T _D + T _CR
= [1 / (B + 1)] _TIN + _TCR (14)
ΔT = T _R −T _L = [(1-B) / (B + 1)] • T _IN
+ (1-ρ) · T _CR ] (15)

The main part of the control function in the electronic control unit 36 of this embodiment is the same as that shown in FIG. 4, but the control amount determining means 60 determines the control amount using the control equation shown in the following equation (16). It is different in the point to do. The main part of the control operation in the electronic control unit 36 of the present embodiment is the same as that shown in FIG. 5 except that the control amount is determined from the control equation shown in the following equation (16) in S5. To do. The following equation (16) is obtained by arranging ΔT in the above equation (15) as ΔT _REQ . This equation (16) can also be simplified as shown in equation (9), similarly to the aforementioned equation (8).

_{T CREQ = [(1-B} ) / (B + 1)] · T IN + (1-ρ) · ΔT REQ]
... (16)

  Also in the present embodiment, for example, in order to obtain the target left-right torque difference ΔT with high accuracy in the control of torque movement by the first clutch C1 and the second clutch C2 in order to obtain the target left-right torque difference, the differential device 42 is used. The differential limiting torque (represented by the bias ratio B) derived from the mechanical differential limiting characteristic is corrected in consideration of the differential limiting torque of the differential device 42 based on the mechanical differential limiting characteristic of the differential device 42. Since the control amounts for the first clutch C1 and the second clutch C2 (engagement element) are accurately calculated, the same effect as in the above-described embodiment can be 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 the front and rear wheel drive vehicle based on the front engine front wheel drive has been described, but the present invention is not limited to this. It can be applied to various types of vehicles such as front engine front wheel drive (FF) vehicles, front engine rear wheel drive (FR) vehicles, and front and rear wheel drive vehicles based on front engine rear wheel drive. is there.

  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.

  In the above-described embodiment, the transmission 44 is constituted by two sets of planetary gear units, and the transmission 68 is constituted by three sets of planetary gear units. The configurations of the transmissions 44 and 68 are as follows. Any structure that can shift the rotation of the sun gear S3 (fourth rotating element RE4) with respect to the ring gear R1 (first rotating element RE1) may be used, and a structure that uses one or three or more planetary gear units, double Various other types of transmissions such as a configuration with two planetary gear devices of a pinion type and a single pinion type may be used, and not only an increase in speed but also a reduction speed change may be used.

  In the above-described embodiment, the differential device 42 is constituted by a double pinion type planetary gear device. However, the planetary gear including 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.

  In the above-described embodiment, the rotation of the carrier CA2 is locked by the brake BK used for switching the torque movement. However, 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.

  In the above-described embodiment, the brake BK is provided between the carrier CA2 of FIG. 2 and the non-rotating member 45 such as the housing. However, the brake BK is omitted and the carrier CA2 is replaced with the non-rotating member 45 such as the housing. It may be fixed.

  In the second embodiment, a brake may be provided between the carrier CA2 and the non-rotating member 45 in FIG.

  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 rear wheel side of the power transmission system of FIG. 1. It is a figure explaining the action | operation limitation characteristic of the driving force distribution device for vehicles of FIG. 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. It is a skeleton figure explaining the structure of the driving force distribution apparatus provided in the rear-wheel side of the power transmission system of the other Example of this invention.

Explanation of symbols

26: Vehicle driving force distribution device 36: Electronic control device (control device)
42: Differential device (differential part)
44, 68: Transmission (transmission unit)
60: Control amount determining 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, first frictional engagement) Equipment)
C2: Second clutch (engagement element, second friction engagement device)
BK: Brake

Claims (9)

In a vehicle driving force distribution device that includes a differential device that distributes input torque input from a drive source to left and right drive wheels, and an engagement element that generates a torque difference between the left and right drive wheels. A control device for a vehicle driving force distribution device that controls the engagement element so as to obtain a target left-right torque difference,
A control device for a vehicle driving force distribution device, wherein a control amount to the engagement element is determined based on a preset mechanical differential limiting characteristic of the differential device.   2. The vehicle driving force distribution according to claim 1, further comprising control amount determination means for determining a control amount to the engagement element by a control equation having the target left-right torque difference and the input torque as variables. Control device for the device.   The control amount determining means includes a left-right drive wheel torque difference indicated by the target left-right torque difference and a left-right drive wheel torque difference generated by a mechanical differential limiting characteristic of the differential device. The control amount is determined so that the torque difference between the left and right drive wheels indicated by the target left-right torque difference is larger than the same case when the torque distribution tendency of the drive wheels differs. The control device for a vehicle driving force distribution device according to claim 1 or 2.   The control amount determining means includes a left-right drive wheel torque difference indicated by the target left-right torque difference and a left-right drive wheel torque difference generated by a mechanical differential limiting characteristic of the differential device. When the torque distribution tendency of the drive wheels is different, when the input torque input from the drive source is large, the torque difference between the left and right drive wheels indicated by the target left-right torque difference is larger than when the input torque is small. The control amount of the vehicle driving force distribution device according to claim 1 or 2, wherein the control amount is determined to be The differential device includes a first rotating element to which the input torque is input, a second rotating element and a third rotating element to which a left driving wheel and a right driving wheel are connected, respectively.
A speed changer that shifts the rotation transmitted to the first rotation element and transmits the rotation to the fourth rotation element;
As the engaging element, a first friction engagement device that transmits torque transmitted to the fourth rotating element to the second rotating element, and torque transmitted to the fourth rotating element to the third rotating element. A second friction engagement device for transmitting,
5. A control amount for controlling a torque transmission capacity generated in the first friction engagement device and the second friction engagement device is determined by the control amount determination means. A control device for a vehicle driving force distribution device.   6. The vehicle according to claim 5, wherein the differential device distributes the torque by removing a torque transmission capacity of the first friction engagement device or the second friction engagement device from an input torque input from the drive source. Control device for driving force distribution device. The ratio of the torque to one of the left and right drive wheels showing the mechanical differential limiting characteristic of the differential device is B, the speed ratio of the transmission is ρ, and the input torque input from the drive source is T _IN , when the target left-right torque difference is ΔT _REQ , the control amount determination means uses the torque T _CREQ generated by the first friction engagement device or the second friction engagement device according to the following equation as the control amount. The control device for a vehicle driving force distribution device according to claim 5, wherein the control device is calculated.
_{T CREQ = [(B-1} ) T IN + (1 + B) ΔT REQ] / (1 + B-ρ + ρ · B) The differential device includes a first rotating element to which the input torque is input, a second rotating element and a third rotating element to which a left driving wheel and a right driving wheel are connected, respectively.
A transmission is provided for increasing the speed of the rotation transmitted to the second rotation element, transmitting it to the fourth rotation element, decelerating and transmitting it to the fifth rotation element;
As the engaging element, a first friction engagement device that transmits torque transmitted to the fifth rotating element to the third rotating element, and torque transmitted to the fourth rotating element to the third rotating element. A second friction engagement device for transmitting,
5. A control amount for controlling a torque transmission capacity generated in the first friction engagement device and the second friction engagement device is determined by the control amount determination means. A control device for a vehicle driving force distribution device. The control amount determining means is configured such that the ratio of the other to one of the torques to the left and right drive wheels indicating the mechanical differential limiting characteristic of the differential device is B, the speed ratio of the transmission is ρ, and When the input torque to be input is T _IN and the target left-right torque difference is ΔT _REQ , the control amount determination means generates torque T to be generated by the first friction engagement device or the second friction engagement device according to the following equation. _9. The control device for a vehicle driving force distribution device according to claim 8, wherein _CREQ is calculated as the control amount.
_{T CREQ = [(1-B} ) / (B + 1)] · T IN + (1-ρ) · ΔT REQ]

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