JP2859697B2 - Torque distribution control device for four-wheel drive vehicle - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a torque distribution control device for a four-wheel drive vehicle.

(Prior Art) In a four-wheel drive vehicle that drives four wheels in front, rear, left and right by an engine output, the torque distribution of each wheel is not always set to the same state, but is variably controlled to the optimum distribution according to the driving state. Such a torque distribution control device is generally known.

For example, Japanese Patent Application Laid-Open No. 1-247223 discloses that a turning motion of a vehicle is divided into a turning approach, a turning, and a turning escape, and torque distribution control is performed according to a turning state of the vehicle based on a steering angle of a front wheel and a steering angle change rate. There is a proposal to perform the following. In other words, this proposal reduces the torque distribution to the front wheels by absorbing the driving force of the front wheels by the brakes in order to increase the turning performance of the vehicle when turning and entering, while reducing the driving force of the rear wheels to increase straightness when turning and exiting. To reduce the torque distribution to the rear wheels and to make the load on the tires of the front and rear wheels uniform.

(Problems to be Solved by the Invention) By the way, in the vehicle, a skid occurs on the wheels depending on the condition of the road surface, and the slip amount also changes. Particularly, on a low μ road surface where the friction coefficient of the road surface (hereinafter referred to as μ as necessary) is small, the side slip of the rear wheels tends to increase.

However, by merely determining the torque distribution ratio between the front wheels and the rear wheels based on the steering angle and the rate of change described above, it is possible to suppress an increase in the sideslip of the rear wheels during cornering, especially to suppress the sideslip of the rear wheels during escape. It is difficult to equalize the load on the front and rear wheels.

That is, in the case of the above-described conventional technique, when the steering angle starts to decrease by a predetermined amount or more, the torque distribution to the rear wheels is reduced. At this time, a large skid has already occurred on the rear wheels on a low μ road surface, It is difficult to suppress this side slip with the torque distribution according to the steering angle (or the steering angle change rate). Therefore,
When the vehicle starts to show a spin tendency, the driver needs to reduce the steering amount. In addition, the control for decreasing the torque distribution to the rear wheels is stopped when the steering angle becomes zero.However, on a low μ road surface, it is normal that the rear wheels still have large sideslip even at this time, and the vehicle goes straight. It is difficult to quickly converge to the running state.

Therefore, when the spin tendency of the vehicle is detected, it is conceivable to reduce the amount of torque distribution to the rear wheels to suppress the spin tendency. However, since the requirements of the driver are different, simply controlling the vehicle cannot improve the steering stability and turning performance of the vehicle.

An object of the present invention is to suppress the above-mentioned sideslip of the rear wheel, and to make it possible to perform a stable turning travel, especially on a low μ road surface.

(Means for Solving the Problem) The present invention corrects such a problem in accordance with the steering angle state, the amount of torque distribution to the rear wheels determined based on the spin tendency.

That is, a torque distribution control device for that purpose is shown in FIG.

In the figure, reference numeral 1 denotes a four-wheel drive vehicle, and an engine 2
The output of the engine 2 is transmitted to the left and right front wheels 6, 7 and the left and right rear wheels 8, 9 via a center differential 3, a front differential 4, and a rear differential 5, respectively.

Numeral 10 is a torque distribution changing means for adjusting the amount of transmission of the engine output to the four wheels 6 to 9 and changing the torque distribution to the four wheels 6 to 9. The transmission amount is adjusted by controlling the brake devices 11 to 14 provided.

And, for the control of the torque distribution changing means 10,
A spin tendency detecting means 17 for detecting a spin tendency of the vehicle,
The output of the steering angle state detecting means 40 for detecting the steering angle state and the output of the spin tendency detecting means 17 are set so that the torque distribution to the rear wheels 8, 9 is reduced when the spin tendency of the vehicle is detected. Torque distribution setting means 80 and the steering angle state detecting means
In accordance with the steering angle state detected by 40, the rear wheels 8,
A torque distribution control means for controlling the torque distribution changing means based on the torque distribution to the rear wheels corrected by the correction means; (The invention of claim 1).

The invention according to claim 2 is different from the invention according to claim 1 only in the configuration of the correction means, and the correction means includes the steering angle state detection means.
In accordance with the steering angle state detected by 40, the amount of torque distribution to the rear wheels set by the torque distribution setting means 80 at the time of escaping from turning traveling is reduced and corrected.

According to the third aspect of the present invention, the steering angle state detecting means according to the first or second aspect detects a steering angle change rate, and the correction means 81 controls the rear wheel in accordance with an increase in the steering angle change rate. The amount of correction of the amount of torque distribution to the motor is increased. Further, in the invention of claim 4, the steering angle state detecting means 40 in claim 1 or 2 detects the steering angle, and the correcting means 81 sends the signal to the rear wheels in accordance with the increase of the steering angle. This is to increase the correction amount of the torque distribution amount. Further, in the invention of claim 5, the spin tendency detecting means 17 in claim 1 or 2 detects the spin tendency of the vehicle by the side slip angle, and in the invention of claim 6, the spin tendency is determined.
Is a means for detecting the tendency of the vehicle to spin based on the difference between the sideslip angle of the front wheels and the sideslip angle of the rear wheels.

(Operation) In the above torque distribution control device, when the vehicle has a tendency to spin, the torque distribution to the rear wheels is reduced.
The spin tendency of the vehicle is suppressed.

As described above, when the vehicle tends to spin, the rear wheels 8,
The torque distribution to the rear wheel 9 is set to be small, but it is corrected so that the amount of torque distribution to the rear wheels increases when entering the turning travel according to the steering angle state such as the steering angle and the steering angle change rate. As a result, the torque distribution to the front wheels 6, 7 is reduced, so that the turning performance of the vehicle can be obtained.

At the time of escaping from the cornering, the torque distribution of the rear wheels 8, 9 is greatly reduced by the decrease control of the torque distribution to the rear wheels for the spin and the decrease correction control by the steering angle state. Side skidding is suppressed. And then
Even if the rudder angle becomes zero, as long as skidding remains on the rear wheels 8, 9 as in the case of running on a low μ road surface, the rear wheels
The reduction control of the torque distribution to 8, 9 is continued, and the side slip can be reduced promptly to converge the vehicle to the straight running state.

(Effects of the Invention) Therefore, according to the present invention, the reduction control of the torque distribution to the rear wheels during the spin tendency is corrected according to the steering angle state.
It is possible to obtain an improvement in turning performance at the beginning of a turn or an improvement in maneuverability at a later stage of the turn.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

<Description of Overall Configuration> FIG. 2 shows the overall configuration of the embodiment (the same reference numerals are used for components corresponding to those shown in FIG. 1).

First, the output of the engine 2 is input via a transmission 31 to a transfer 3 having a center differential for equally transmitting the engine output to the front wheel side and the rear wheel side. The front differential 4 is connected to a front wheel output shaft 32 of the transfer 2, and left and right front wheels 6 and 7 are connected to the front differential 4 via a front wheel drive shaft 33. Similarly, rear differential 5
Is connected to a rear wheel output shaft 34 of the transfer 3, and the rear left and right rear wheels 8 and 9 are connected to the rear differential 5 by a rear wheel drive shaft 35.
Are connected via

Brake controller 10 as torque distribution changing means
Are the brake devices 11 to 14 disposed on the four wheels 6 to 9 respectively.
And a brake pressure control valve for separately controlling the brake pressure supplied to the motor and its actuator. The opening of the throttle valve 36 of the engine 2 is adjusted by a throttle motor 37.

Reference numeral 15 denotes an engine controller as engine output changing means, which receives an accelerator signal from an accelerator sensor 38 that detects an accelerator operation amount of the driver, outputs an operation control signal to the throttle motor 37, and outputs an operation control signal to the throttle motor 37. While the opening degree of the throttle valve 36 is adjusted to correspond to the accelerator operation amount, the control signal from the torque distribution controller 16 as a torque distribution control means is received, and the engine output torque necessary for changing the torque distribution is obtained. It changes the engine output.

The torque distribution controller 16 uses the accelerator sensor 38
In addition to the above signals, various signals for measuring the amount of movement or the amount of operation for performing the torque distribution control to the four wheels 6 to 9 are input, and control signals are output to the brake controller 10 and the engine controller 15. The output sources of the various signals are as follows.

A steering angle sensor 40 as a steering angle state detecting means for detecting a steering angle of a wheel A wheel speed sensor 44 for detecting a rotation speed of each wheel 6 to 9 A rotation speed sensor 45 for detecting an engine rotation speed 45 A vehicle speed sensor 46 A gear of the transmission 25 Gear position sensor 47 for detecting position (gear position) Boost pressure sensor for detecting boost pressure of engine 2
48 The yaw rate sensor 49 for detecting the yaw rate of the vehicle 49. That is, the torque distribution controller 16 determines the torque distribution ratio between the front wheels 6, 7 and the rear wheels 8, 9 according to the turning state of the vehicle. R1) and left wheel 6,
A distribution ratio setting means for setting a torque distribution ratio R2 between the right wheels 7 and 9 (hereinafter referred to as a left / right distribution ratio as required) R2, and a turning state determining means for setting the distribution ratio are provided. In addition, in order to set the front-rear distribution ratio R1, a side slip angle detecting unit 17 as a spin tendency detecting unit for detecting a side slip angle of the rear wheel is provided.

<Description of Brake Controller 10> In FIG. 3, reference numeral 59 denotes a first hydraulic line for the brake device 11 of the front wheel 6, and reference numeral 60 denotes a second hydraulic line for the brake device 12 of the right front wheel 7, each of which is a brake. First and second brake pressure control valves 61 and 62 for controlling the supply of pressure are provided. The two braking pressure control valves 61 and 62 are configured such that the cylinders 61a and 62a are controlled by pistons 61b and 62b to change the volume of the chambers 61c and 62c and the control chambers 61d and 62c.
It is divided into d. The variable volume chambers 61c and 62c apply the braking pressure generated by the master cylinder 58 to the brake devices 11 and 12 described above.
Is to be supplied to

The pistons 61b, 62b are urged by the springs 61e, 62e in a direction in which the volumes of the variable volume chambers 61c, 62c increase, and are urged by the control pressure introduced into the control chambers 61d, 62d. The variable displacement chambers 61c, 62c are moved in the direction of contraction, and are provided with check valves 61f, 62f that close the braking pressure inlets of the variable volume chambers 61c, 62c by the movement in the contraction direction. Therefore, the control pressure is introduced into the control chambers 61d, 62d, and the pistons 61b, 62b are moved by the springs 61e, 6b.
When moving against 2e, the master cylinder 58 and the variable volume chamber
61c, 62c are cut off and these chambers 61c, 6c
The braking pressure generated in 2c is supplied to each of the brake devices 11, 12.

On the other hand, in order to operate each of the braking pressure control valves 61 and 62, first and second actuators 63 and 64 each including a pressure increasing solenoid valve 63a, 64a and a pressure reducing solenoid valve 63b, 64b are provided. Have been. The pressure increasing solenoid valves 63a and 64a
Are disposed on control pressure supply lines 69, 70 leading to the control chambers 61d, 62d of the braking pressure control valves 61, 62 via a relief valve 66, and the pressure reducing solenoid valves 63b, 64b are disposed in the control chambers 61d, 62d. Are arranged on the drain lines 67 and 68 led from. These solenoid valves 63a, 63b, 64a, 64b are controlled to open and close by a signal from the torque distribution controller 16, and when the pressure-increasing solenoid valves 63a, 64a are opened and the pressure-reducing solenoid valves 63b, 64b are shut off. When the control pressure is introduced into the control chambers 61d, 62d of the braking pressure control valves 61, 62, the pressure increasing solenoid valves 63a, 64a are shut off and the pressure reducing solenoid valves 63b, 64b are opened, the control chambers 61d, 62d are opened.
The control pressure from is discharged.

The brake devices 13 and 14 for the left and right rear wheels 8 and 9 are not shown, but have the same structure as the brake devices 11 and 12 for the front wheels 6 and 7 described above. Independent braking pressure can be applied to the brake devices 11 to 14.

Next, the torque distribution controller 16 will be described.

<Overall Processing Flow> At a predetermined measurement timing after the start, the overall processing flow is based on the signals from the sensors 38, 40, 44 to 49 shown in FIG. The steering angle, each wheel speed, the engine speed, the vehicle speed, the gear position, the boost pressure, the actual yaw rate of the vehicle are measured, the front-rear distribution ratio R1 and the left-right distribution ratio R2 are set according to the turning state, and the brake controller 10 and The control of the engine controller 15 is performed.

In the present embodiment, the front-rear distribution ratio R1 is 0 for front-rear uniform distribution, and a drive torque of 0 (rear wheel) for the front wheels 6 and 7 at +0.5.
The driving torque is the maximum at 8, 9), and the opposite relationship is set at -0.5. The left / right distribution ratio R2 is set so that 0 is a right / left uniform distribution, and a driving torque of 0 (the driving torque of the right wheels 7, 9 is maximum) at +0.5 and a reverse relationship at −0.5. ing.

<Turning state control> This control basically determines the front-rear distribution ratio R1 based on the sideslip angle of the rear wheels 8, 9, while determining the left-right distribution ratio R2 so as to obtain a target yaw rate. It is. Then, the distribution ratios R1 and R2 are corrected according to the turning state of the vehicle.

Specifically, the control is executed according to the flow shown in FIG. First, the turning state is determined (step S2
1) If the vehicle is turning (step S22), the rear wheels 8,
The determination of the front-rear distribution ratio R1 based on the sideslip angle of 9 and the determination of the left-right distribution ratio R2 based on the yaw rate are sequentially performed (step S2).
3, S24). Then, in the case of the approach state and the exit state of the turning traveling, the front-rear distribution ratio R1 is determined based on the steering angle and the steering angle change rate.
Is performed (steps S25 to S28).

-Determination of Turning State (Step S21)-Here, the turning state of the vehicle is determined from the steering angle and the steering angle change rate obtained by the steering angle sensor 40, and a turning state determination flag F is obtained. In this case, the meaning of the flag is as follows.

F = 0: straight traveling state; rudder angle is less than a predetermined value F = 1: entry state to turning traveling; rudder angle change rate is more than a predetermined value in a positive direction (direction of increasing steering angle) F = 2: turning traveling State: The steering angle is equal to or greater than a predetermined value and the steering angle change rate is less than a predetermined value. F = 3 ... Escape state from turning traveling; The steering angle change rate is equal to or more than a predetermined value in a negative direction (steering angle decreasing direction). The determination in S22 is based on the straight running condition (F =
0) is excluded from the control target.

-Slip angle control (step S23)-This is based on the sideslip angle detection means and the front-rear distribution ratio setting means, and as shown in the flow chart of FIG.
Is detected, and the front-rear distribution ratio R1 is set based on the sideslip angle (steps S31 and S32). Thus, in the case of the present example, the sideslip angle of the rear wheels 8, 9 due to the influence of the yaw motion of the vehicle is detected.

That is, the influence angle γ of the yaw motion on the sideslip of the wheels 6 to 9 can be expressed by the following equation (see FIG. 6).

γ = Yaw.r · l / V Yaw.r; Yaw rate l; Distance of each wheel from the center of gravity of the vehicle V; Vehicle speed Therefore, the sideslip angle γr of the rear wheels 8,9 due to the above yaw motion is as follows: , And can be obtained by detecting the vehicle speed V and the yaw rate Yaw.r using the vehicle speed sensor 46 and the yaw rate sensor 49.

γr = Yaw.r · lr / V lr; distance of rear wheel from center of gravity of vehicle Incidentally, the influence angle γf of yaw motion on sideslip of front wheels 6 and 7 is as follows.

γf = Yaw.r · lf / V lf; distance of the front wheels from the center of gravity of the vehicle Therefore, assuming that the steering angle of the front wheels 6, 7 is θ, the sideslip angle of the front wheels 6, 7 due to the yaw motion is θ−γf. Become. Therefore, in this case, the side slip angle difference Δβ between the front wheels 6, 7 and the rear wheels 8, 9
Is Δβ = θ−γf−γr. That is, the front wheel steering angle θ
On the other hand, in the region where γr is small, Δβ> 0 and the front wheels 6,
The side slip angle of 7 is larger than the side slip angle of the rear wheels 8,9, but when the above γr increases, Δβ <0, and the rear wheels 8,9
The sideslip angle of 9 is larger than the sideslip angle of the front wheels 6 and 7, and the vehicle exhibits a so-called spin tendency.

Thus, in step S32, according to the characteristic map shown in this step, based on the sideslip angle γr of the rear wheels 8, 9, as the γr increases in the plus or minus direction, the torque distribution of the rear wheels 8, 9 is performed. This is to set the front-rear distribution ratio R1 so that the torque distribution is reduced, and constitutes the torque distribution setting means 80. In this case, the yaw rate Yaw.r takes a right turn in the positive direction, and the above-mentioned γr is plus or minus, which corresponds to a right turn and a left turn of the vehicle.

-Yaw rate correction (step S24)-In determining the left / right distribution ratio R2 based on the yaw rate,
Calculate the target yaw rate Y.cal corresponding to the high μ road surface from the minimum wheel speed v, the steering angle θ, and the wheelbase L, and calculate the target yaw rate Y.cal from the difference from the measured yaw rate Yaw.r. The feedback control of R2 is performed.

In this case, the target yaw rate Y.cal is calculated by the following equation.

Y.cal = V / (1 + Av ² ) · θ / LA where A is a factor obtained from the characteristic map shown in FIG.

Then, ΔY = Y.cal−Yaw.r is obtained, a drive torque difference between the left and right wheels corresponding to the deviation ΔY is obtained, and then a ratio of the drive torque difference to the driver required torque is obtained, and this is calculated as a left / right distribution ratio R2. It is assumed that. Specifically, it is as follows.

R2 = k ・ ΔY / Tr k is a constant for obtaining a driving torque difference between the left and right wheels corresponding to the deviation ΔY, and Tr is a driver required torque. this
Tr detects an accelerator opening and an engine speed (RPM) by an accelerator sensor 38 and a speed sensor 45, and calculates a driving torque of the engine from a map shown in FIG. 8 based on the accelerator opening and a gear position sensor 47. From the gear ratio detected from the above.

Next, the correction of the front-rear distribution ratio R1 based on the steering angle and the steering angle change rate will be described.

In the state of entry into the cornering (F = 1), the characteristic diagram of the correction coefficients a and b and the calculation formula of R1 (R1 = a +
As described in (b + R1), correction is performed such that R1 increases as the steering angle increases and as the steering angle change rate increases. On the other hand, in the state of escape from turning (F = 3), the characteristic diagram of the correction coefficients a and b and the calculation formula of R1 (R1 = a + b + R) are added to step S28.
As described in 1), as the steering angle increases and as the steering angle change rate increases,
Correction is performed so that R1 is reduced.
Is composed.

<Engine and Brake Control> Calculate the torque Ts required to execute the torque distribution control based on the front / rear distribution ratio K1 = Q1 + R1 and the left / right distribution ratio K2 = Q2 + R2, which is the total of the distribution ratios set by the preceding controls. .

Ts = 4 × (| K1 | +0.5) × (| K2 | +0.5) × Tr Then, while controlling the engine controller 15 so as to obtain the required torque Ts, based on the distribution ratios K1 and K2. Braking torque TBFR (for right front wheel), TBFL (for left front wheel), TBRR (for right rear wheel) and TBRL applied to each wheel 6-9
(For the left rear wheel) is calculated in accordance with the following equation, and the brake controller 10 is controlled so that these braking torques can be obtained.

TBFR = Ts-4 (0.5-K1) x (0.5 + K2) x Ts TBFL = Ts-4 (0.5-K1) x (0.5-K2) x Ts TBRR = Ts-4 (0.5 + K1) x (0.5 + K2) x Ts TBRL = Teng−4 (0.5 + K1) × (0.5−K2) × Ts <Operation of the Embodiment>-At the time of approach to turning-The front-rear distribution ratio R1 increases as the sideslip angle γr of the rear wheels 8, 9 increases. Although the torque distribution to the rear wheels 8 and 9 is set to be small, it is corrected according to the steering angle θ and the steering angle change rate. As a and b increase, this R1 becomes larger than zero. Therefore, the torque distribution of the front wheels 6 and 7 is reduced, so that the turning performance of the vehicle can be obtained. Further, since the left / right distribution ratio R2 is set by feedback control so as to obtain a yaw rate that targets characteristics on a high μ road surface, a large yaw rate can be obtained even on a low μ road surface to improve the turning performance. it can.

-During turning-On the low μ road surface, the side slip angle γr of the rear wheels 8, 9 increases as the vehicle continues to turn, so that the front-rear distribution ratio R1 by the slip angle control increases in the negative direction. On the other hand, during steady turning, the rate of change of the steering angle becomes substantially zero, so that the correction coefficient b also becomes substantially zero. As a result, even if the correction coefficient a according to the steering angle θ affects the front-rear distribution ratio R1, the total front-rear distribution ratio R1 becomes smaller than zero as the side slip angle γr increases. Therefore, the rear wheel 8,
Since the torque distribution to the rear wheels 9 is reduced, an increase in the sideslip of the rear wheels 8, 9 on a low μ road surface is suppressed.

-At the time of escape from turning traveling-At this time, the front-rear distribution ratio R1 is increased in the minus direction by the slip angle control and the correction control based on the steering angle θ and the steering angle change rate (both a and b are minus). Therefore, the torque distribution of the rear wheels 8, 9 is greatly reduced, so that the sideslip of the rear wheels 8, 9 is suppressed. Thus, even when the steering angle θ becomes zero, as in the case of traveling on a low μ road surface, the rear wheels 8,
As long as the skid remains in 9, the slip distribution control sets the front-rear distribution ratio R1 to a value smaller than zero in accordance with the magnitude of the skid angle γr. The decrease control is continued, and the side slip can be quickly reduced to converge the vehicle to the straight running state.

Therefore, in this control, although the front-rear distribution ratio R1 is corrected by the steering angle θ and the steering angle change rate, since the control is basically performed by the side slip angle γr of the rear wheel, the ninth control is performed.
As shown in the figure, the control region in which the torque distribution of the rear wheels 8, 9 is reduced is such that the sideslip angle γr of the rear wheels 8, 9 increases,
From the point in time at which the difference between the sideslip angles of 6, 7 is reduced (this point can be changed by setting the correction coefficients a, b) to the point of the sideslip angle γr = 0 of the rear wheels 8, 9 become.

On the other hand, if the front and rear torque distribution control is performed based only on the steering angle θ and the rate of change thereof, the control region for reducing the torque distribution of the rear wheels 8 and 9 becomes the front wheel steering angle θ after steady turning. From the point at which the front wheel steering angle has decreased by a predetermined amount or more to the point at which the front wheel steering angle θ = 0, which is a narrow value.

In other words, in the case of this control, when the μ of the road surface is low, the rear wheels 8, 9 are likely to skid, and accordingly, the control region for reducing the torque distribution of the rear wheels 8, 9 is automatically expanded. Before the vehicle starts to show a spin tendency, the driving force of the rear wheels 8 and 9 can be reduced to suppress the side slip without waiting for the driver to reduce the steering amount. Of the vehicle can be stabilized.

In the above embodiment, the sideslip angle of the rear wheels is indirectly detected from the yaw rate of the vehicle. However, the sideslip angle may be directly detected from the sideslip state of the vehicle.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of the present invention. FIG. 2 and subsequent figures show an embodiment of the present invention, FIG. 2 is an overall configuration diagram, FIG. 3 is a circuit diagram showing torque distribution changing means, FIG. FIG. 6 is a flow chart of the slip angle control, FIG. 6 is a plan view showing the side slip angle of the vehicle, FIG. 7 is a characteristic diagram showing the relationship between the wheel speed and the factor A, and FIG. 8 shows the relationship between the output torque and the accelerator opening. FIG. 9 is a characteristic diagram comparing a control region for decreasing the torque distribution of the rear wheels based on the slip angle and a control region based on the front wheel steering angle. DESCRIPTION OF SYMBOLS 1 ... 4 wheel drive vehicle 2 ... Engine 3 ... Center differential 4 ... Front differential 5 ... Rear differential 6-9 ... Wheels 10 ... Torque distribution changing means 11-14 ... Brake device 16 ... Torque Distribution control means 17 Slip angle detection means 40 Steering angle sensor 44 Vehicle speed sensor 49 Yaw rate sensor 80 Torque distribution setting means 81 Correction means

Claims (6)

(57) [Claims] In a four-wheel drive vehicle in which four front, rear, left and right wheels of the vehicle are driven by engine output, the amount of engine output transmitted to the four wheels is controlled to change the distribution of drive torque to the four wheels. Torque distribution changing means, spin tendency detecting means for detecting the spin tendency of the vehicle, steering angle state detecting means for detecting the steering angle state, and receiving the output of the spin tendency detecting means and detecting the spin tendency of the vehicle. A torque distribution setting means for setting the torque distribution to the rear wheels to be small, and a torque distribution setting means for setting the torque distribution setting means at the time of entering the turning travel according to the steering angle state detected by the steering angle state detection means. Correction means for increasing the corrected torque distribution to the rear wheels, and torque distribution control means for controlling the torque distribution changing means based on the torque distribution to the rear wheels corrected by the correction means. A torque distribution control device for a four-wheel drive vehicle, characterized in that: 2. In a four-wheel drive vehicle in which four front, rear, left and right wheels of the vehicle are driven by engine output, the amount of engine output transmitted to the four wheels is controlled to change the distribution of drive torque to the four wheels. Torque distribution changing means, spin tendency detecting means for detecting the spin tendency of the vehicle, steering angle state detecting means for detecting the steering angle state, and receiving the output of the spin tendency detecting means and detecting the spin tendency of the vehicle. A torque distribution setting means for setting the torque distribution to the rear wheels to be small, and a torque distribution setting means at the time of escaping from the turning travel in accordance with the steering angle state detected by the steering angle state detection means. Correction means for correcting the reduced amount of torque distribution to the rear wheels, and torque distribution control means for controlling the torque distribution changing means based on the torque distribution amount to the rear wheels corrected by the correction means. A torque distribution control device for a four-wheel drive vehicle, comprising: 3. A steering angle state detecting means for detecting a steering angle change rate, and a correcting means for increasing a correction amount of a torque distribution amount to rear wheels according to an increase in the steering angle change rate. The torque distribution control device for a four-wheel drive vehicle according to claim 1 or 2, wherein 4. The steering angle state detecting means detects a steering angle, and the correcting means increases a correction amount of a torque distribution amount to rear wheels in accordance with an increase in the steering angle. 3. The torque distribution control device for a four-wheel drive vehicle according to claim 1 or 2. 5. The torque distribution control device for a four-wheel drive vehicle according to claim 1, wherein the spin tendency detecting means detects the tendency of the vehicle to spin based on a side slip angle. 6. The torque distribution of a four-wheel drive vehicle according to claim 1, wherein the spin tendency detecting means detects the tendency of the vehicle to spin based on a difference between the sideslip angle of the front wheels and the sideslip angle of the rear wheels. Control device.