JP2908493B2 - Powertrain control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention relates to a torque distribution control function for varying a torque distribution amount to front and rear wheels and left and right wheels in a four-wheel drive vehicle or to left and right wheels in a two-wheel drive vehicle. The present invention relates to a power train control device for a vehicle having two functions of a slip control function for varying a braking force of each wheel according to a slip state of each wheel.

BACKGROUND ART Conventionally, torque distribution control (or torque split control) and slip control (or traction control) have been performed in order to ensure the running stability of a vehicle.
The former is intended to appropriately distribute the engine torque applied to each wheel, mainly for the purpose of improving the traveling performance when traveling on a curve or starting. In other words, the torque distribution control performs torque distribution control in consideration of a change in load on wheels caused by a change in vehicle attitude caused by an accelerator operation or a steering operation by a driver. Further, the latter slip control is for ensuring the slip state of the wheel optimally. In other words, the slip control is for controlling a wheel slip caused by a cause independent of the operation of the driver (for example, running on a low-resistance road).

As described above, both the torque distribution control and the slip control have been developed with their own problems, and the control is also performed by each system. Since the driving torque for the wheels is controlled to change, one control inevitably affects the other. Therefore, a power train control device according to the present invention has been proposed with the aim of eliminating adverse effects on vehicle travel due to mutual interference by the two controls.

Hereinafter, first, the configuration, operation, and problems of various related arts related to slip control or torque distribution control that have been already disclosed or proposed will be described, and then the specifics of the present invention will be described. The problem or configuration will be described in detail.

(Conventional technology) Conventionally, for example, a four-wheel drive vehicle (hereinafter referred to as a 4WD vehicle)
Various technical ideas for distributing different torques to the front, rear, left and right wheels have been proposed. For example,
As shown in the specification and the drawings of Japanese Patent Application Laid-Open No. 60-248440, the output from the engine is firstly distributed to each wheel by a center differential, and the braking forces of the front, rear, left and right wheels are mutually controlled. Control means are provided individually so as to be able to be independently controlled separately.If a slip occurs in relation to the road surface condition on each of the left and right wheels on the front wheel or the rear wheel side, the specific wheel that is slipping is Technical means for controlling the driving force of the wheel by applying a braking force to the wheel to substantially reduce the driving force (wheel driving force control means)
Is known. When the slipping wheel is braked in this manner, a torque difference occurs between the torque value of the other wheel and the torque value of the other wheel. As a result, an appropriate driving force can be obtained in each of the front, rear, left and right wheels.

Originally, a vehicle normally comes into contact with the ground by four wheels, and its slip limit performance is determined by the friction coefficient μ of the road surface.
And the load (W) on the tire (wheel), and is limited by the frictional force of the tire uniquely determined by the product (μ · W). Then, the force applied to the tire includes various elements such as a driving force, a braking force, and a centrifugal force, but if a value obtained by adding these in a vector is not within the above-described frictional force value of the tire, A stable running performance of the vehicle cannot be obtained.

By the way, with respect to the load W applied to the tire, when the load is moved by the acceleration in the vehicle longitudinal direction and the lateral direction generated during running, a load difference occurs between each of the four front and rear wheels, thereby the tire supporting the movement of the vehicle. There is also a difference in ability as a. In particular, when the coefficient of friction μ with the road surface is low, the load W greatly affects the running stability of the vehicle.

Therefore, in the four-wheel drive vehicle as described above, the load per tire is reduced by appropriately distributing the driving torque to the four wheels as described above, and even on a road surface having a low friction coefficient μ of the road surface. Stable vehicle running performance is obtained. However, in the above case, if the front and rear left and right wheels are connected to each other by the center differential, the same driving torque is inevitably distributed to the front and rear wheels. As a result, the slip tends to occur on the side of the lightly loaded wheel, so that the performance of the car is restricted by the tire with the lowest capacity, and the other wheel with the higher load cannot fully exert its capacity. There is.

On the other hand, in the above-described four-wheel drive vehicle, when different torque distribution is performed between the front and rear wheels in consideration of such circumstances, the road surface grip performance of the tire at each wheel is more effectively exhibited. However, if this torque distribution is changed by adjusting the degree of connection (frictional force) of, for example, the clutch disposed in the center differential, a large engine output is inevitably distributed directly. In addition, the structure of the clutch unit itself becomes large, which causes a restriction on mounting, and thus naturally has a disadvantage that the weight is increased and the cost is increased.

However, if the brake device is provided so as to be independently operable on the front and rear wheels as in the configuration of the prior art described above, and a slip occurs on the front wheel or the rear wheel, braking force is applied to the slipping wheel. In the case of controlling to add, a part of the engine output is used due to the braking force, and the wheels are decelerated, so that the traveling performance, particularly, the acceleration performance is reduced.

Therefore, recently, the following torque split (distribution) control has been proposed. That is, as described above, a state in which it is necessary to perform different torque distribution between the front and rear wheels or the left and right wheels is caused by an acceleration that is caused by the movement of the vehicle load on the wheels on the road surface having a low friction coefficient μ and the vehicle load accompanying the vehicle acceleration. There are two main cases, that is, the case of running and the case of turning when the centrifugal force is applied to the wheels in addition to the driving force. In such a state, the tire output is usually determined by the engine output. Since there is a large torque allowance and a loss of engine output is tolerated to some extent, even if the torque split control is performed, almost no deceleration occurs. Therefore, it is not necessary to provide a mechanism for directly changing the transmission amount in a torque transmission path such as a clutch.

In the four-wheel drive vehicle that transmits the engine output (engine torque) to the front and rear left and right wheels as described above, the torque split control device includes, for example, an engine output control unit that variably controls the engine output, A braking force (braking force) control means for variably controlling the braking forces on the left and right wheels independently of each other is provided. The operation of the engine output control means and the braking force control means is controlled by a torque distribution changing means, and the braking force acting on one of the front and rear wheels or the left and right wheels by the braking force control means and the braking force by the engine output control means are controlled. , The amount of torque distribution to the front and rear wheels or the left and right wheels is changed by increasing the engine output.

In the above-described torque split control device for a four-wheel drive vehicle, the braking force control means applies a predetermined amount of braking force to one of the front and rear wheels or the left and right wheels whose torque is to be reduced, and the braking force is reduced by the braking force. The engine output corresponding to the torque is distributed to the other wheels by the engine output control means. As a result, the total value of the engine output including the increase in the engine output is appropriately distributed and transmitted to the front and rear wheels and the rear wheels, respectively. The torque that is reduced by the amount of the braking force and actually acts on the road surface from all the wheels is the same as before the change in the torque distribution amount, that is, the same as before the braking operation, and only the torque transmitted to the braking side wheels. Is reduced, and the torque of the non-braking wheels is relatively increased.

As a result, the road surface grip force of the wheel in the slip state is improved, and the slip state is prevented, so that the running stability of the vehicle is improved.

On the other hand, there is a so-called slip control (traction control) as a drive wheel control system for a four-wheel drive vehicle similar to the above-described torque split control. In general, when the amount of slip of wheels on the road surface is large when the vehicle is running, grip running on the road surface is not performed, and proper running characteristics itself such as drift out due to wheel spin cannot be obtained. . Therefore,
In such a case, similar to the above-described torque split control, the brake device provided in the vehicle is operated, or the output of the engine is reduced to control the slip of the drive wheel on the road surface. Is used.

Such a slip control device suppresses a slip phenomenon of a drive wheel with respect to a road surface by detecting a state in which the drive wheel is slipping at a predetermined level or more with respect to the road surface, or by detecting a state in which the drive wheel slips with respect to the road surface. In order to set a target slip ratio or the like serving as a reference for a drive wheel causing the above-described slip, it is first required to detect a vehicle speed. In the case of a two-wheel drive vehicle in which only one of the front wheels and the rear wheels is driven, the vehicle speed can be relatively easily detected based on the peripheral speed of the driven wheel that is less likely to slip on the road surface. In a four-wheel drive vehicle in which both the front wheels and the rear wheels can be driven as described above, when the vehicle is in the four-wheel drive state, there will be no driven wheels. Therefore, its detection becomes difficult.

In order to solve such a disadvantage of detecting the slip ratio in a four-wheel drive vehicle, Japanese Patent Application Laid-Open No. 62-289429 discloses an example.
As shown in Japanese Patent Application Laid-Open Publication No. H10-209, first, a peripheral speed of each wheel in a four-wheel drive vehicle is obtained, and based on the peripheral speed, a state in which each wheel is slipping over a road surface by a predetermined value or more is detected. In addition, there has been proposed a slip control device for a four-wheel drive vehicle configured to specifically estimate the vehicle speed based on the minimum value among the peripheral speeds of the respective wheels.

As described above, in the slip control device of the four-wheel drive vehicle in which the state in which each wheel is slipping on the road surface is detected and the vehicle speed is estimated, the slip state of the wheel with respect to the road surface is equal to or more than a predetermined value. When it is detected, usually, a drive that acts on a wheel in which a slip condition equal to or more than the predetermined value is detected so that a slip ratio or a slip amount of the wheel in which the slip condition is detected matches a predetermined target value. Control for reducing the torque is performed. The target value in the control is set irrespective of the number of wheels for which a slip greater than or equal to the predetermined value is detected.

In general, in a four-wheel drive vehicle, the number of wheels whose slip on the road surface is detected depends on the running state of the vehicle and the road surface condition (road surface friction coefficient and the like). The larger the number of wheels that are slipping over a predetermined level,
The effect on the running stability of the vehicle is great. Therefore, it is desired that the larger the number of wheels in which a slip of a predetermined level or more is detected, the lower the target value of the slip rate or the amount of slip in the slip control is, and the priority is given to ensuring the running stability of the vehicle. . Further, as the number of wheels in which a slip of a predetermined level or more is detected is smaller, the target value of the slip rate or the slip amount in the slip control is set higher to secure the traveling characteristics of the vehicle such as acceleration and running performance. Is desired to be given priority.

For this reason, recently, for example, when a slip state equal to or higher than a predetermined level value is detected for each wheel in a four-wheel drive vehicle, the slip rate or the slip amount for the detected wheel is set to a set target value. In order to match, a torque control means for changing a driving torque acting on the wheel is provided. At this time, a target value of a slip rate or a slip amount for the controlled wheel is set according to a traveling state of the vehicle or a road surface condition. In this situation, even a highly accurate four-wheel-drive vehicle slip control device configured to obtain desired running characteristics under a condition in which the running stability of the vehicle is substantially ensured has been proposed.

 The above is an overall overview of the prior art.

(Problems to be Solved by the Invention) As described above, the slip control (traction control) and the torque distribution control (torque split control) of the drive wheels greatly contribute to the stability of the running state of the vehicle, and the stability is improved. The present inventors have concluded that, in a vehicle configured with both of these systems, when the two systems operate simultaneously, the following problem may be caused. They found.

That is, for example, even when the torque distribution (split) control is performed based on the amount of movement of the vehicle body or the amount of operation of the driver, there are two cases in which the slip control may be hindered and the case in which the slip control is not performed. Therefore, the torque distribution control must be performed according to the situation. In other words, when the slip control is hindered and the running stability of the vehicle is impaired, the torque distribution control must be stopped inevitably. Performing the above operation results in an unnecessary decrease in acceleration performance.

On the other hand, when the torque distribution control is performed according to the amount of movement of the vehicle body or the amount of operation of the driver as described above, the ability of the tires of the front and rear wheels can be maximized as described above. However, if the driving force is increased beyond the limit of the tire performance which originally varies depending on the road surface condition (particularly the road surface μ), the occurrence of wheel spin cannot be prevented. For example, on a low μ road such as a snow-covered road, the limit difference in tire performance due to the vehicle motion state is small. Therefore, in such a case, there is a concern that increasing the amount of distribution of the driving force itself may cause a spin phenomenon of the entire wheel, depending on the wheel position or the number of wheels.

Therefore, in such a case, it is assumed that the above-described slip control is naturally performed, thereby reducing the torque acting on the wheels to prevent the spin state. If the vehicle suddenly shifts to the slip control while the vehicle is running, the control of the wheels on the road surface, which should originally reduce the driving force, is lost. In addition, there is a problem that the behavior of the vehicle body becomes unstable due to a sudden change in the drive power distribution amount.

(Object of the invention of claim 1) Therefore, first, the object of the invention of claim 1 of the present application is to apply the slip control target wheel when the torque distribution control is to be executed for the wheel on which the slip control is executed. An object of the present invention is to prevent the increase of the distribution torque due to the torque distribution control for the vehicle, thereby speeding up the convergence of the slip of the slip wheels and promptly securing the running stability.

(Means for Solving the Problem of the Invention of Claim 1) The structure of the problem solving means of the invention of claim 1 of the present invention for achieving the object and solving the above-mentioned problem is that a wheel having an engine output torque is provided. In a power train control device that controls transmission to the whole, a torque distribution control unit that independently distributes output torque from the engine to each wheel while variably controlling the distribution amount, and each of the wheels. Slip control means for detecting a slip state and performing slip control so that the detected slip amount of a slip wheel is equal to or less than a predetermined level; and a wheel on which slip control is performed by the slip control means. Torque determining means for determining whether or not the torque distributed to the wheel is increased when the torque distribution controlling means operates; When the torque distributed to the slip control target wheel is increased in response to the output of (i), at least the slip control means or the torque distribution control means is controlled so as to decrease the torque allocated to the slip control target wheel. And a torque suppressing means for suppressing the transmission torque to the slip control target wheel.

(Operation of the Means for Solving the Problems of the First Embodiment) First, the slip control (traction control) works so as to reduce the torque acting on the wheels to prevent the occurrence of a spin state.

On the other hand, the torque distribution control (split control) controls the amount of torque distribution to each wheel according to the amount of movement of the vehicle body or the amount of operation of the driver, and makes the most efficient use of the tire capacity of each wheel. be able to.

However, when the above-described slip control is performed, a spin occurs in one or two of the wheels, and when only the brake control is performed, the torque distribution control is performed.
As a result, when the torque distribution amount of the control target wheel exceeds the limit of the performance of the tire, the occurrence of wheel spin cannot be prevented.

On the other hand, when the amount of torque distribution to the control target wheel by the torque distribution control becomes smaller, the occurrence of wheel spin can be effectively prevented by the slip control.

Therefore, in the configuration of the power train control device according to the first aspect of the present invention, in addition to the torque distribution control means for performing the torque distribution control and the slip control means for performing the slip control, the distribution to the wheels to be subjected to the slip control and the torque distribution control is performed. Torque judgment means for judging an increase in torque and torque suppression for suppressing transmission torque to the slip control target wheels by controlling the slip control means or the torque distribution control means according to the judgment result of the torque judgment means. Means is provided, whereby the torque transmitted from the torque distribution control means to the wheels to be slip-controlled when the distributed torque is increased is suppressed.

As a result, even if the torque distribution control is started during the slip control, if the amount of the torque distributed to the slip control target wheel increases, the torque transmission amount is automatically suppressed, and It acts to suppress the generation of wheel spin as much as possible.

(Effect of the Invention of Claim 1) Therefore, according to the power train control device according to the invention of claim 1 of the present application, slip control can be effectively utilized within a range in which the tire capacity has a margin, and The slip state can be maintained at an optimal state for traveling.

Further, even during the slip control, sufficient torque can be distributed as long as the tire capacity has a margin, so that it is possible to appropriately respond to a driver's acceleration request.

(An object of the invention of claim 2) An object of the invention of claim 2 of the present application is that the torque distribution control is originally performed when the slip control is going to be further performed. For wheels with less distributed torque by control, by suppressing the increase in distributed torque by slip control,
Another object of the present invention is to prevent a new slip from occurring on a wheel having a small distribution torque.

(Means for Solving the Problems of the Invention of Claim 2) The structure of the means for solving the problems of the invention of the present invention, which achieves the above object and solves the above-mentioned problems, is described in detail below. In the power train control device that controls the transmission of the entire vehicle, the torque distribution control means that independently distributes the output torque from the engine to each wheel while variably controlling the distribution amount, and the slip amount of the wheel. Slip control means for performing slip control so as to be equal to or lower than a predetermined level, first detection means for detecting a wheel to be controlled by the slip control means, and an output of the first detection means; When the torque distribution control means is operating, slip control is about to be performed on the wheel to be slip-controlled by the slip control means. Detecting means for detecting whether the torque to be distributed to the wheels to be slip-controlled is equal to or greater than a predetermined value, based on the output of the second detecting means. When the torque transmitted to the slip control target wheel is equal to or more than a predetermined value in response to the output of the torque determination unit, the torque control unit suppresses an increase in torque to the slip control target wheel. It is characterized by being provided.

(Operation of the Problem Solving Means of Claim 2) The torque distribution control (split control) controls the amount of torque distribution to each wheel according to the amount of movement of the vehicle body or the amount of operation by the driver. The ability of the tire can be utilized to the fullest extent.

The slip control (traction control) works so as to reduce the torque acting on the wheels to prevent the occurrence of a spin state.

By the way, when the torque distribution control is executed in accordance with the amount of movement of the vehicle body or the amount of operation of the driver as described above, the ability of the tires of each of the front and rear wheels can be utilized to the utmost. In particular, when the driving force becomes large beyond the limit of the tire capacity which varies depending on the road surface μ), the occurrence of wheel spin cannot be prevented as described above. For example, on a low μ road such as a snow-covered road, the limit difference in tire performance due to the vehicle motion state is small. Therefore, in such a case, there is a concern that increasing the amount of distribution of the driving force itself may rather cause a spin phenomenon of the entire wheel depending on the wheel position or the number of wheels.

Therefore, in such a case, it is naturally assumed that the above-described slip control is performed, thereby reducing the torque acting on the wheels to prevent the spin state. If the control is suddenly shifted to the slip control during the execution, the control of the wheels on the road surface, which should originally reduce the driving force, is lost, and a new spin wheel is generated. In addition, there has been a problem that the vehicle body behavior becomes unstable due to a sudden change in the driving force distribution amount.

Thus, in the configuration of the power train control device according to the second aspect of the present invention, in addition to the torque distribution control means and the slip control means, a first wheel for slip control to be controlled by the slip control means is detected.
Receiving the detection output of the first detection means,
Second detecting means for detecting that slip control is about to be performed on the wheel to be slip-controlled by the slip control means when the torque distribution control means is operating, and the second detecting means Output of
Torque determining means for determining whether the torque to be distributed to the slip control target wheel is equal to or greater than a predetermined value, and torque transmitted to the slip control target wheel in response to an output of the torque determination means Is greater than or equal to a predetermined value, a torque suppression means is provided to suppress an increase in torque to the outdoor slip control target wheel, and slip control is performed on the predetermined wheel when torque distribution control is being performed by the torque distribution control means. If it is to be applied, an increase in the torque distribution amount of the torque distribution control means is suppressed in accordance with the distribution torque value of the controlled wheel.

As a result, it is possible to prevent the occurrence of a new spin generating wheel at the time of switching transition in which the slip control is applied to the spin generating wheel during the torque distribution control.

Therefore, according to the power train control device of the second aspect of the present invention, even if the slip control is executed during the torque distribution control, the control force of the wheels on the road surface is stable. , And changes in vehicle body behavior do not occur.

(Embodiment) Hereinafter, two embodiments of the power train control device according to the present invention (basic first embodiment and improved second embodiment) will be described in detail.

In each of these embodiments, the torque distribution control (torque split control) according to the change in the load distribution on the wheels is performed, for example, by increasing the braking amount for the wheels whose torque is to be reduced, For each wheel whose torque is to be increased, this is done by reducing the amount of braking. The engine torque lost by the addition of the braking force is made available by increasing the entire engine output.

The slip control for optimizing the slip state of the wheels includes a brake control for setting a target slip ratio for each of the four wheels and applying an appropriate braking force to each wheel toward the target slip ratio. The engine torque is controlled by controlling the output of the engine from the difference between the engine output and the target slip rate to control the slip rate of the wheels.

In the control device according to the first embodiment, the torque split control in which the additional torque appropriately corresponds to the change in the load applied to the wheels and the slip control (traction control) for eliminating the slip of the wheels are independent of each other. It is executed to improve running stability and acceleration of the vehicle.

On the other hand, in the control device of the second embodiment, in the control by the control device of the first embodiment, since the slip control and the torque split control are performed independently, the two controls eventually interfere with each other. This has been done with particular consideration that a situation may occur. Such situations are mainly the following two situations. That is: When a slip is generated and the torque split (torque distribution) control is independently performed on the wheel subjected to the slip control by the control of the first embodiment, the same torque split is performed on the wheel. The control may increase the driving torque in some cases. Such an increase in the driving torque further promotes the slip. To prevent this, if such a situation is detected, the increase in the torque due to the torque split control for the wheel to be slip-controlled is suppressed. What you want to do. Such an interference state is referred to as a first interference state in the description of the second embodiment, which will be specifically described later.

: In the above-described torque suppression control, an increase in driving torque is suppressed for wheels on which slip control is performed,
It is characterized in that the occurrence of slip is prevented.
However, on the other hand, for a wheel that originally has a small amount of torque distribution, such suppression or prohibition of the torque distribution itself leads to an increase in torque, and as a result, excessive driving force exceeding the ability of the tire is applied to the wheel. As a result, dangerous drift-out may occur. Therefore, in the second embodiment, even when the torque split control is stopped as described above and the control is shifted to the slip control, the wheel in which the applied torque is actually reduced has the wheel actually slipping. Regardless, torque split control is performed to prevent the generation of a new slip wheel.

On the premise of the above, first, the configuration of the hardware unit common to the power train control devices of the first and second embodiments will be specifically described, and then the first and second power train control devices will be described.
The detailed contents of the control operation of each of the second embodiments will be sequentially described.

<System Configuration of Hardware Unit of Power Train Control Device> First, FIG. 1 shows an overall configuration of a hardware unit of a control system of each power train control device of the first and second embodiments. 4 is conceptually shown together with the basic vehicle structure of a four-wheel drive vehicle.

That is, as shown in FIG. 1, an in-line four-cylinder engine 12, for example, is mounted on the front part of the vehicle body 10 of the four-wheel drive vehicle. This engine 12 has four cylinders 11, 11, ...
Each of the cylinders 11.11 is provided with a fuel supplied from a fuel supply system and intake air through an intake passage 16 provided with a throttle valve 14 which is electrically opened and closed by a throttle actuator 13. The formed air-fuel mixture having a predetermined air-fuel ratio is supplied. The air-fuel mixture supplied into each of the cylinders 11 is combusted by the operation of an ignition system (not shown) such as a spark plug, a distributor, an igniter, etc., and then discharged through an exhaust passage 17. The combustion of the air-fuel mixture causes the engine 12 to rotate, and the generated torque is transmitted to the transmission 22, the center differential mechanism 23, and the propeller shaft 24 for the front wheels.
And a left front wheel 20L and a right front wheel 20 via a torque transmission path formed including a differential mechanism 25, a propeller shaft 26 for a rear wheel, and a differential mechanism 27.
R, the left rear wheel 21L, and the right rear wheel 21R.

A brake control unit 30 is provided in association with the left front wheel 20L, the right front wheel 20R, the left rear wheel 21L, and the right rear wheel 21R. The brake control unit 30 includes a disc 32 attached to each of the left front wheel 20L, the right front wheel 20R, the left rear wheel 21L, and the right rear wheel 21R.
And a caliper 34 provided with a brake pad for pressing the disc 32. The caliper 34 in each of the disc brakes 35A to 35D is provided with a wheel cylinder 36, and each wheel cylinder 36 has a conduit 37a extending from the hydraulic pressure adjusting unit 40.
To 37d are respectively connected. When the brake fluid pressure is supplied to the wheel cylinder 36 from the fluid pressure adjusting unit 40 via the conduits 37a to 37d, the respective calipers 34 apply the brake pads to the disc 32 with a pressing force corresponding to the supplied brake fluid pressure. Press, front left wheel 20L, front right wheel 20R, rear left wheel 21
Each of the L and the right rear wheel 21R is independently braked.

The hydraulic pressure adjusting unit 40 is supplied with hydraulic pressure according to the depression operation of the brake pedal 41 from a power cylinder 43 provided in association with the brake pedal 41 through conduits 42a and 42b, and a pump 44 and a pressure regulating valve. The hydraulic pressure formed by 45 is supplied through conduit 46. Hydraulic pressure adjustment section 40
During normal braking in which traction control, that is, slip control is not performed, a normal brake fluid pressure is formed in accordance with the depression operation of the brake pedal 41 and supplied to the disc brakes 35A to 35D through conduits 37a to 37d. The brake control operation is performed, and the disc brake is operated according to the operating state of the built-in solenoid valves 51 to 58 during the slip control.
An operation of individually forming brake fluid pressures for 35A to 35D and selectively supplying them to the disc brakes 35A to 35D is performed.

The electromagnetic on-off valves 51 to 58 include electromagnetic on-off valves 51 and 52, electromagnetic on-off valves 53 and 54, electromagnetic on-off valves 55 and 56, and electromagnetic on-off valves 57 and 58.
Of each pair, each of which is a left front wheel 20
L, the right front wheel 20R, the left rear wheel 21L, and the right rear wheel 21R are involved in adjusting the brake fluid pressure for the disc brakes 35A to 35D provided respectively. When one of the solenoid on-off valves 51, 53, 55 and 57 of each set is opened and the other on-off valves 52, 54, 56 and 58 are closed,
The brake fluid pressures supplied to the disc brakes 35A to 35D are respectively increased, and conversely, one of the solenoid valves 51, 53, 55, and 57 of each of the above sets is closed, and the other solenoid valve is closed. When the on-off valves 52, 54, 56 and 58 are opened,
When the brake fluid pressure supplied to the disc brakes 35A to 35D is reduced, and each of the sets is closed, the brake fluid pressure supplied to the disc brakes 35A to 35D changes to the current fluid pressure state. It is kept as it is.

The respective open / close states of the respective solenoid on-off valves 51 to 58 are appropriately controlled according to control purposes by illustrated control signals Ca to Ch from a brake control unit of the control unit 100 as described later. I have.

That is, in this embodiment, in addition to the components described above, a brake control unit for controlling the opening and closing of the electromagnetic on-off valves 51 to 58, a throttle control unit for controlling the operation of the throttle actuator 13, and a torque to each wheel are provided. A control unit 100 having a built-in torque distribution control unit for performing distribution is provided. The control unit 100 first includes a left front wheel 20L and a right front wheel 20L for slip control (traction control).
R, speed sensors 61 to 64 provided in association with each of the left rear wheel 21L and the right rear wheel 21R. Left front wheel 20L, Right front wheel 2
0R, a signal representing the peripheral speed of each of the left rear wheel 21L and the right rear wheel 21R
VFL, VFR, VRL, VRR, throttle pedal opening degree (θt) obtained from throttle opening degree sensor 65, and accelerator pedal obtained from accelerator opening degree sensor 67 provided in association with accelerator pedal 66 A stepping amount θa of 66 and a steering angle signal θs of the left front wheel 20L and the right front wheel 20R obtained from a steering angle sensor 69 provided in association with the steering wheel 68 are supplied and input.

The following table (Table 1) lists each data signal used for the following control.

-Outline of Power Train Control of Each Embodiment-<First Embodiment> Next, an outline of the power train performed in the first embodiment will be described first.

First, the control unit 100 detects the detection signals VFL, V
FR, VRL, VRR are sequentially fetched at a predetermined cycle, and the left front wheel 20 represented by each of the fetched detection signals VFL, VFR, VRL, VRR.
L, the value of the estimated vehicle speed and the value of the circumferential acceleration are calculated based on the values of the peripheral speeds of the right front wheel 20R, the left rear wheel 21L, and the right rear wheel 20R, respectively.
Whether or not a slip of a predetermined value or more has occurred in each of the left front wheel 20L, the right front wheel 20R, the left rear wheel 21L, and the right rear wheel 21R is determined by determining the value of each calculated circumferential acceleration in advance. The determination is made by comparing with the reference value Aa. And the left front wheel
20L, the right front wheel 20R, the left rear wheel 21L and the right rear wheel 21R include those for which the value of the circumferential acceleration is determined to be equal to or more than the reference value Ae.
Assuming that a slip of a predetermined level or more has occurred, slip control is performed, and on the other hand, it is determined that the value of each peripheral acceleration of the left front wheel 20L, the right front wheel 20R, the left rear wheel 21L, and the right rear wheel 21R is less than the reference value Aa. In this case, normal throttle opening control is performed.

When the normal throttle opening control is performed by the control unit 100, a normal target throttle opening is set according to the depression amount of the accelerator pedal 66 represented by the accelerator depression amount detection signal θa. A throttle valve drive signal (A) corresponding to the difference between the normal target throttle opening and the opening of the throttle valve 14 so that the opening of the throttle valve 14 represented by the throttle opening detection signal θt approaches the normal target throttle opening. A feedback control signal) Ct is formed and supplied to the throttle actuator 13. Thus, the throttle valve 14 is driven to be opened and closed by the throttle actuator 13, and its opening is controlled so as to be equal to the normal target throttle opening. The normal target throttle opening is set so as to increase with a predetermined proportional relationship (linear characteristic) as the depression amount of the accelerator pedal 66 increases. When the slip control is performed by the control unit 100, the left front wheel 20L, the right front wheel 20R, and the left rear wheel 21L
The detected value of the circumferential acceleration for each of the right rear wheel 21R and the right rear wheel 21R is used, and first of all, a wheel in which a slip of a predetermined level or more with respect to the road surface has occurred (hereinafter, referred to as a slip wheel) is any of the four wheels. That, and the number of slip wheels are each detected, and if the number of detected slip wheels is more than one, the number of slip wheels that became slip wheels substantially simultaneously among the plurality of slip wheels is The detected vehicle speed is detected, and the calculation of the estimated vehicle speed used for setting the target slip ratio and the setting of the slip control mode are performed based on the detection result.

<Estimation of vehicle speed> In setting the estimated vehicle speed by the control unit 100, the detection signals VFL,
VFR, VRL, VRR represent front left wheel 20L, front right wheel 20R, rear left wheel 2
An estimated vehicle speed value V _n-1 (where n is a positive integer) calculated based on each peripheral speed of 1L and the right rear wheel 21R is a predetermined reference value.
Vh or higher, and the calculated estimated vehicle speed value Vn _-1 is less than the reference value Vh, and the steering angle signal θ
During low-speed straight traveling steering angle of the left front wheel 20L and the right front wheel 20R is a predetermined reference value θ less than ₁ s represents the left front wheel 20L, right front wheel 20R, left rear wheel 21L and the right rear wheel 21R circumferential speed of A predetermined correction coefficient α ₀ (where α ₀ <1) is assigned to the lowest value among the values.
And the estimated vehicle speed value Vn at that time is calculated (Vn = αo × Min {VFL, VFR, VRL, VRR}). The value V _n-1 of the estimated vehicle speed is less than the reference value Vh, at the time of low-speed turning of the steering angle θs of the left front wheel 20L and the right front wheel 20R is a value theta ₁ or more, sensed slip wheel and the number thereof Accordingly, the estimated vehicle speed is set in a different setting mode based on the peripheral speed of a wheel (hereinafter, referred to as a non-slip wheel) in which a slip of a predetermined value or more with respect to the road surface has not occurred. I have.

In setting the estimated vehicle speed during low-speed turning,
Under the detection that the number of slip wheels is zero or one, when the left turning state of the vehicle is detected based on the steering angles of the left front wheel 20L and the right front wheel 20R, the left front wheel 20L and the right front wheel 21R are detected.
Calculated when There are each non-slip wheels, prearranged correction coefficient alpha ₁ defined is multiplied by the average value of the peripheral speed of the peripheral speed and the right rear wheel 21R of the left front wheel 20L, the value Vn of the estimated vehicle speed When at least one of the left front wheel 20L and the right rear wheel 21R is detected to be a slip wheel, and when a left turn of the vehicle is detected, the periphery of the right front wheel 20R which is a non-slip wheel is detected. speed and is multiplied by the correction coefficient alpha ₁ to the average value of the peripheral speed of the left rear wheel 21L, the value Vn of the estimated vehicle speed is calculated. On the other hand, when it is detected that the number of slip wheels is zero or one and the right turning state of the vehicle is detected, when the right front wheel 20R and the left rear wheel 21L are non-slip wheels, respectively. , the circumferential velocity and the left rear wheel 21L of the right front wheel 20R correction coefficient to the average value of the peripheral speed alpha ₁ is multiplied, the estimated vehicle speed value Vn is calculated, also of the right front wheel 20R and the left rear wheel 21L When it is detected that at least one of the wheels is a slip wheel and the right turn of the vehicle is detected, the average value of the peripheral speed of the left front wheel 20L and the peripheral speed of the right rear wheel 21R, which are non-slip wheels, is used. correction coefficient alpha ₁ is multiplied, the estimated vehicle speed value Vn
Are respectively calculated.

Further, when it is detected that the number of slip wheels is two, if the non-slip wheels are the left front wheel 20L and the right front wheel 20R, or the left rear wheel 21L and the right rear wheel 21R, the left front wheel
Average value of the peripheral speed of 20L of peripheral speed and the right front wheel 20R, or predetermined correction coefficient α estimation ₂ is multiplied to the average value of the peripheral speed of the peripheral speed and the right rear wheel 21R of the left rear wheel 21L Vehicle speed value Vn
Is calculated. Further, when the non-slip wheels are the left front wheel 20L and the left rear wheel 21L, or the right front wheel 20R and the right rear wheel 21R, among the non-slip wheels, the wheel taking the locus closest to the locus of the center of gravity of the vehicle. value Vn of the estimated vehicle speed is calculated correction coefficient alpha ₂ is multiplied by the peripheral speed. Specifically, when the non-slip wheel is the left front wheel 20L and the rear left wheel 21L, the vehicle if a right turn condition correction coefficient alpha ₂ in the circumferential speed of the left front wheel 20L is multiplied, also vehicle correction coefficient alpha ₂ is multiplied by the peripheral speed of the left rear wheel 21L is the case of the left-turning. On the other hand, the left slip wheel, right front wheel 20R and when it is the right rear wheel 21R, the vehicle if a right turning right peripheral speed of front wheels 20R correction coefficient alpha ₂ multiplied by the vehicle is turning left state in it are correction coefficient alpha ₂ in the circumferential speed of the right rear wheel 21R is multiplied if the value Vn of the estimated vehicle speed in each case is calculated.

On the other hand, when the non-slip wheels are the left front wheel 20L and the right rear wheel 21R, or the right front wheel 20R and the left rear wheel 21L, the left front wheel
Average value of the peripheral speed of the peripheral speed and the right rear wheel 21R of 20L, or the right front wheel 20R peripheral speed and the left rear wheel 21L to the average value of the peripheral speed correction coefficient alpha ₂ is multiplied is in the estimated vehicle speed value Vn Is calculated.

When it is detected that there are three slip wheels, the peripheral speed of the remaining non-slip wheels is multiplied by the correction coefficient α ₃ to calculate the estimated vehicle speed value Vn.

Furthermore, front left wheel 20L, front right wheel 20R, rear left wheel 21L and rear right wheel 2
When it is detected that all the 1Rs are slip wheels, the value Vn of the estimated vehicle speed calculated immediately before the detection of the slip wheel is used as the value Vn of the estimated vehicle speed at that time.

The above-mentioned correction coefficients α ₁ , α ₂ and α ₃ are set to 1> α ₁ > α ₂ > α in consideration of the fact that the vehicle is in an unstable state as the number of slip wheels increases. _It is desirable that the values are sequentially set smaller so as to be ₃ .

As described above, the estimated vehicle speed is set based on the setting mode according to each determination result such as which of the four wheels is the slip wheel (wheel position) and the number of slip wheels. However, for example, the running state of the actual vehicle is considered under a relatively simple configuration without using an expensive ground speed sensor or the like, and is set to an appropriate value for control without greatly deviating from the actual vehicle speed. Will be.

<Slip control> Under the state where the estimated vehicle speed is set as described above, the control unit 100 performs the slip control on the slip wheels according to the number of the slip wheels and information on which wheel is slipping. This is performed as follows according to a predetermined control mode. That is, in the slip control by the control unit 100,
First, the number of slip wheels (slip wheel number counter
4 which is stored in the SN) and represents the wheels that are slipping
In accordance with the combination of the three flags (SFFR, SFFL, SFFL, SFRR), the brake control hydraulic circuit 30
A brake control (braking force variable control) for applying a braking force to each of the left front wheel 20L, the right front wheel 20R, the left rear wheel 21L, and the right rear wheel 21R, and an engine opening by reducing the opening of the throttle valve 14 The throttle control (engine torque variable control) for reducing the output is selectively performed. The target slip ratio TGBR introduced for the brake control is determined by three predetermined control constants TG1.
TG3 (provided that 0 <TG1 <TG2 <TG3) is set to the smallest value TG1. Further, the target slip ratio TGTR introduced for the throttle control is selected and set to one of the values TG1 to TG3. Here, the slip ratio is defined as (wheel speed-vehicle speed) / wheel speed.

Then, the respective values of the target slip rate TGBR in the brake control and the target slip rate TGTR in the throttle control set in this way are calculated by the correction coefficient γ stored in the internal memory set in advance for each number of slip wheels. The values of the target slip ratios TGBR and TGTR are corrected by multiplying the values according to the number of slip wheels at that time. The correction coefficient γ multiplied by each of the target slip rate TGTR and the target slip rate TGTR is set to 1 when the number of slip wheels is one, and is set to a smaller value as the number of slip wheels increases. .

Thus, as the number of slip wheels increases, the correction coefficient γ
Is set to a smaller value, the values of the target slip rates TGBR and TGTR corrected and multiplied by the correction coefficient γ are
Specifically, the running state of the vehicle and the road surface condition (particularly road surface resistance μ)
It will be according to.

In performing the brake control and the throttle control, the value of the estimated vehicle speed calculated as described above is used.
Vn is used, and the actual slip ratios SFL, SFR, S at the left front wheel 20L, the right front wheel 20R, the left rear wheel 21L, and the right rear wheel 21R, respectively.
SRL = (VFLn−Vn) / VFLn, SRL
= (VFRn-Vn) / VFRn, SRL = (VRLn-Vn) / VRLn, and SRR
= (VRRn-Vn) / VRRn.

When the brake control is actually performed, the actual slip ratio SF calculated for each wheel as described above is used.
Based on a comparison between L, SFR, SRL, and SRR, and the value of the target slip ratio TGBR corrected and multiplied by the correction coefficient γ, the drive signals Ca to Ch are selectively formed by the control unit 100. Is the electromagnetic opening / closing valve 51 for varying the braking force described above.
~ 58. As a result, the left front wheel 20L and the right front wheel 20
R, the brake fluid pressure for the disc brakes 35A to 35D attached to the left rear wheel 21L and the right rear wheel 21R is adjusted, and the slip rate of the slip wheel is adjusted to the target slip rate TGBR corrected by multiplying by the correction coefficient γ. Controlled to match the value.

On the other hand, when the throttle control is performed, the actual slip ratios SFL, SFR, SRL, and SRR calculated as described above are multiplied by the correction coefficient γ to obtain the corrected target slip ratio TGTR. Based on the comparison, the control unit 100 forms a throttle valve drive signal Ct, which is supplied to the throttle actuator 13 for variable engine torque control. As a result, the opening degree of the throttle valve 14 is adjusted to perform torque control, and the actual slip ratio of the slip wheels is controlled so as to be equal to the value of the target slip ratio TGTR corrected by multiplying the correction coefficient γ.
However, during the throttle control, when the opening degree θt of the throttle valve 14 is set to be larger than the normal target throttle opening degree set according to the depression amount θa of the accelerator pedal 66, the throttle control is stopped. Normal throttle opening control is started.

<Control Pattern> With reference to FIG. 2, a control mode in the first embodiment and the second embodiment will be described.

(A) In the case of one slip wheel As described above, the brake control and the throttle control in the slip control are selectively performed according to the number of slip wheels and the combination of the slip wheels. When this is detected, only brake control is performed.

(B) In the case of two slip wheels When it is detected that the number of slip wheels is two, it is determined in advance according to each of six combinations of two of the four wheels. The control is performed according to one of the control modes. That is, when the left rear wheel 21L and the right rear wheel 21R are slip wheels, only the brake control is performed.

On the other hand, when the left front wheel 20L and the right front wheel 20R are slip wheels, the influence on the running stability of the vehicle due to this is smaller than when the left rear wheel 21L and the right rear wheel 21R are slip wheels. Since the target slip rate TGTR is set to a value corrected by multiplying the set value TG3 by the correction coefficient γ in addition to the brake control, the throttle control is performed. 20L and rear left wheel 2
If it is 1L, or right front wheel 20R and right rear wheel 21R,
Since the yaw motion may occur in the vehicle, in addition to the brake control, the throttle control is performed with the target slip ratio TGTR set to a value corrected by multiplying the set value TG2 by the correction coefficient γ. Will be And the slip wheel is the left front wheel 20L and the right rear wheel 21R, or the right front wheel 20R and the left rear wheel 21L
If, only the brake control is performed.

As described above, when it is detected that the number of slip wheels is two, it is considered that the influence on the running stability of the vehicle is relatively small, and only the brake control is performed. The driving torque of the output is not unnecessarily reduced due to the reduction, and the deterioration of the running characteristics inherently required for the vehicle such as acceleration and running performance is suppressed. In addition, when the influence on the running stability of the vehicle is likely to be large, throttle control is performed in addition to the brake control, so that a situation in which yaw motion which affects the running stability of the vehicle is effectively prevented. Is done.

(C) In the case of three slip wheels If three slip wheels are detected and each of them has a slip of a predetermined value or more at substantially the same time, it is determined that the vehicle is in an extremely unstable running state. Therefore, only throttle control is performed in a state where the target slip ratio TGTR is set to a value corrected by multiplying the set value TG2 by the correction coefficient γ. When the slips of the three slip wheels do not occur at the same time or more than a predetermined value, in addition to the brake control,
The throttle control is performed with the target slip ratio TGTR set to a value corrected by multiplying the set value TG2 by the correction coefficient γ.

(D) When there are four slip wheels Further, when it is detected that there are four slip wheels (all wheels), the brake control is stopped and the target slip ratio TGTR is set to zero. Throttle control for bringing the throttle valve 14 into a fully closed state is performed. Then, with the throttle valve 14 fully closed, to determine whether each of the four wheels has been changed to a state in which there is substantially no slip, the average peripheral speed VAV is given by the following equation; (VFLn + VFR
n + VRLn + VRRn) / 4, and using the calculated peripheral velocity average value VAV, the total deviation value ε is calculated by the following formula: ε
= (VFLn-VAV) ² + (VFRn-VAV) ² + (VRLn-VAV) ² +
(VRRn−VAV) ² ), and the deviation ε
Is determined to be equal to or less than a predetermined value Za. And
If it is determined that the sum deviation value ε is larger than the predetermined set value Za (ε> Za), since the slip has not been eliminated for all four wheels yet, the throttle The fully closed state of the valve 14 is maintained. on the other hand,
When it is determined that the total deviation value ε is equal to or less than the value Za (ε ≦ Za), it is determined that substantially all four wheels have no slip, and the slip control for each wheel is restarted. You.

When the slip control is restarted, for example (as shown in FIG. 2), the brake control is not performed until a predetermined period Tx elapses from the time when the deviation value ε becomes equal to or less than the value Za, and the target Only the throttle control is performed with the slip ratio TGTR set to a value corrected by multiplying the set value TG1 by the correction coefficient γ. However, when such throttle control is being performed, the opening degree θt of the throttle valve 14 is larger than the normal target throttle opening degree Tk (θt>) set according to the depression amount θa of the accelerator pedal 66. Tk)
Is established, the throttle control is stopped, and the normal throttle opening control is started. That is, it is prohibited to perform the throttle control beyond the required opening degree of the driver because this may cause the driver to feel uneasy.

As described above, when it is detected that all four wheels have slipped on the road surface by a predetermined value or more, the brake control is stopped and the four wheels are returned to a substantially slip-free state. The throttle valve 14 is maintained in the fully closed state, so that the output of the engine is rapidly reduced. By this control, a situation that affects the running stability of the vehicle is reliably and quickly avoided, and the four wheels are also reliably and quickly returned to a state in which substantially no slip occurs. Therefore, even if a slip of a predetermined level or more occurs in the four wheels, a traveling state in which the estimated vehicle speed and the actual vehicle speed are equal or substantially equal can be obtained in a very short time. Further, after the four wheels are returned to a state where there is substantially no slip, until the period Tx elapses, there is a large possibility that the four wheels will again cause slip, As shown in FIG. 2B, during such a period, only the throttle control is performed so that the occurrence of slip exceeding the predetermined value is suppressed, so that the slip of the four wheels does not substantially occur. The running stability of the vehicle immediately after the operation is reliably ensured.

When the slip control is performed as described above, the values of the target slip ratios TGBR and TGTR are corrected according to the number of slip wheels, and the corrected target slip ratios are corrected.
Since the slip ratio of the slip wheels is controlled so as to match the values of TGBR and TGTR, appropriate slip control according to the running condition of the vehicle and the road surface condition is performed, and the running stability of the vehicle is substantially reduced. As a result, desired running characteristics can be obtained.

<Torque Split Control> On the other hand, a control signal from the torque distribution control unit is output to the throttle control unit and the brake control unit of the control unit 100. The torque distribution control unit includes, for example, an acceleration signal D _FR from a longitudinal acceleration sensor, a lateral acceleration signal D _L from a lateral acceleration sensor, a steering angle signal θs from a steering angle sensor 69, and a signal from a throttle opening sensor 65. A throttle opening signal θt, a boost pressure detection signal B from a boost pressure sensor, an accelerator opening detection signal θa from an accelerator opening sensor 67, and the like are input. The change control of the amount of torque distribution to each wheel is appropriately performed.

When the rear wheels 21L, 21R have a load movement, for example, during starting acceleration, the torque distribution control unit controls the front wheels 20L, 20R.
The braking force is applied to the disc brakes 35A, 35B, and the engine torque corresponding to the braking force is increased, so that the driving torque acting on the road surface from the wheels 20L, 20R, 21L, 21R as a whole is the same. , The torque split control is executed so that the torque distribution amounts are different. Further, during cornering, a braking force is applied to the disc brakes 35A and 35B on the front wheels 20L and 20R when entering a corner. On the other hand, when exiting a corner, braking force is applied to the disc brakes 35C and 35D on the rear wheels 21L and 21R, and when turning left, since the load moves on the right front and rear wheels 20R and 21R, the brake 35A on the left and right front wheels 20L and 21L. Apply braking force to 35V. In a right turn, a braking force is applied to the brakes 35B and 35D on the right and left front wheels 20R and 21R, respectively, and the engine torque corresponding to the torque lost by each of the braking forces is controlled to increase on the other side. The amount of torque distribution acting on each wheel is changed.

<Details of Control Operation of First Embodiment> The slip control (traction control) and the torque distribution control (torque split control) described above are all based on the operation of each control unit of the microcomputer built in the control unit 100. It is done,
Specific individual control programs (basic system) executed by the microcomputer will first be described in detail for slip control with reference to the flowcharts of FIGS.

First, the flowchart of FIG. 3 shows a main program (main routine) of the slip control. And
First, the control operation after the start, after the initialization of each part in step S _101, the following step S ₁₀₂ in addition to the detection signals VFL, etc. described above in, [theta] t, the process of creating a sequentially takes in necessary data and the like θaθs The following process
In Step S ₁₀₃ to S _108, in sequence, the slip determination, vehicle speed estimation control mode setting, the target slip rate correction, the throttle control, the step 10 again executes each brake control
Return to 2.

Slip determination program which is executed in step S ₁₀₃ in the flowchart of FIG. 3, for example as shown in the flowchart of FIG. 4, after the control starts, in step S _111, a counter SN for counting the wheel number of slips simultaneously Is set to zero, and in step _S112 , 1 is set.
Register the peripheral speed value VFL _n-1 of the left front wheel 20L before the cycle in the register V
WO, and the value of the peripheral speed VFL of the left front wheel 20L at that time
Put n in register VWN. Further and save the front wheel slip flag SFFL held in the previous cycle in SFQ, in step S _113, it executes the slip detection program shown in Figure 5.

In this slip detection program shown in FIG. 5, after the start, in step S _131, the peripheral acceleration of the left front wheel 20L by Ji flashing the peripheral velocity of the values VWO previous cycle from the circumferential velocity of the values VWN the current cycle ΔVW calculating a peripheral acceleration ΔVW in step S ₁₃₂ that follows to determine whether a predetermined set value Aa or more. If it is determined that the calculated circumferential acceleration ΔVW is equal to or greater than the set value Aa, it is determined that a slip of a predetermined value or more has occurred in the left front wheel 20L, and step
In _S133 , the slip wheel determination flag SF indicating this is
Set Q to 1 (slip occurs). At the same time, 1 is added to the slip wheel counting counter SN to update the count value of the counter SN. Further, in step S _132, when the peripheral acceleration ΔVW is determined to be less than the reference value Aa is
This slip detection program ends without going through step _S133 . After completing the program of FIG. 5, in step S ₁₁₄ in the flowchart of FIG. 4, the process proceeds to the rear step S ₁₁₅ instead of placing the right front wheel slip plug SFFL the slip wheel determination flag SFQ.

Hereinafter, in steps S _{115 to} S ₁₁₇ , S ₁₁₈
To S ₁₂₁ for the rear left wheel, and S ₁₂₂ to S ₁₂₄ is performed each slip determination for the right rear wheel.

In yet step S _125, stores the left front wheel slip flag SFFL, right front wheel slip flag SFFR, the number of slip wheels slipping wheel number counter SN by each adding left rear wheel slip flag SFRL and the right rear wheel slip flag SFRR . Next, in step _S126 , it is determined whether or not the accelerator pedal 66 is in a released state (a state in which the driver is required to fully close the throttle). In the case of YES determination in which it is determined that the accelerator pedal 66 is in the released state, in a final step _S127 , the slip wheel count counter SN is set to zero, the program is terminated, and If NO in _S126 , that is, if it is determined that the accelerator pedal 66 is not released, the slip determination program ends without going through the step _S127 .

On the other hand, step S ₁₀₄ in the flowchart of FIG. 3
In the vehicle speed estimation to be executed, as shown in the flowchart of example FIG. 6, after the start, first, in step S _140, the value V _n-1 of the estimated vehicle speed that is set to one cycle before is equal to or greater than the reference value Vh It is determined whether or not there is, and the estimated vehicle speed value V _n-1
Is determined to be equal to or greater than the same reference value Vh (YES), in the next step _S141 , the estimated vehicle speed value Vh is changed to the left front wheel 20L, the right front wheel 20R, the left rear wheel 21L and the right rear wheel 21R. peripheral velocity of the values VFLn for each, VFRN, is calculated by multiplying the correction coefficient alpha ₀ in the smallest of VRLn and VRRn, it ends the vehicle speed estimation program. Meanwhile, the above steps
In S _140, when the value V _n-1 of the estimated vehicle speed is determined to be less than the reference value Vh is in the other step S _142, the left front wheel 20L and the right front wheel 2 represents the steering angle detection signal θs
Steering angle 0R determines whether a setting value theta ₁ or more. If the steering angle is determined to be the same set value θ less than _1, the above steps S ₁₄₁ and executed in the same manner as described above, and terminates the vehicle speed estimation program. When the steering angle θs on the other hand the step S ₁₄₂ is YES, which is determined to be the set value theta ₁ or more,
In step _S143 , it is determined whether or not the slip wheel count counter SN is zero or one. If it is determined that the slip wheel count counter SN is zero or one, the control proceeds to step _{S144 to} continue the steering. First, it is determined whether the vehicle is turning right based on the angle θ. Vehicle when it is determined that the right turn state, further in the next step S _145, the right front wheel slip flag SFFR determines whether it is zero. Then, as a result, when the right front wheel slip flag SFFR is determined to be zero, further in step S _146, the left rear wheel slip flag SFRL
Is determined to be zero, and the left rear wheel slip flag SFRL is determined.
If but which it is determined to be zero, in step S _147, wherein the value Vn of the estimated vehicle speed; Vn = {(VFRn + VRLn ) / 2} ×
It is calculated by alpha _1, and ends the estimated vehicle speed setting program. On the other hand in the step S ₁₄₅ and _146, if the respective right front wheel slip flag SFFR and left rear wheel slip flag SFRL is determined not to be zero, step S ₁₄₈
In the equation, the estimated vehicle speed value Vn is calculated by the following equation; Vn = ｛(VFLn + VRRn) /
2} is calculated by × alpha ₁ ends the vehicle speed estimation program.

On the other hand, if the vehicle in step S ₁₄₄ is determined not to right turning state, in step S _151, it is determined whether the left front wheel slip flag SFFL is zero, the left front wheel slip flag SFFL If it is determined to be zero, in step _S152 , the right rear wheel slip flag SFRR
Is determined to be zero. Then, as a result, when the right rear wheel slip flag SFRR is determined to be zero, wherein the value Vn of the estimated vehicle speed at step S _153; Vn =
{(VFLn + VRRn) / 2 } is calculated by × alpha _1, and terminates the vehicle speed estimating program, and the other step S ₁₅₁
If it is determined at ₁₅₂ that the left front wheel slip flag SFFL and the right rear wheel slip flag SFRR are not zero, respectively,
In step S _154, the value Vn of the estimated vehicle speed formula; Vn = {(V
FRn + VRLn) / 2} is calculated by × alpha _1, and ends the vehicle speed estimation program.

On the other hand, if it is determined in step _S143 that the slip wheel count counter SN is not zero or one, then in step _S155 , it is determined whether the slip wheel count counter SN is two, and If it is determined that the count counter SN is 2, the next step
In S _156, it is determined whether the right front wheel slip flag SFFR is zero, when the right front wheel slip flag SFFR is determined not to be zero, in step S _157, the right rear wheel slip flag SFRR is zero It is determined whether or not there is. Then, as a result, when it is determined that the right rear wheel slip flag SFRR is not zero, in step _S158 , it is determined whether the vehicle is in a right turning traveling state. If it is determined that the vehicle is in a right-turn running state,
In S _159, the value Vn of the estimated vehicle speed formula; calculated by Vn = VFLnXa2, ends the vehicle speed estimation program. Also,
In step S _158, if it is determined that the vehicle is not in the right turning traveling state, in step S _160, the estimated vehicle speed after value Vn formula; calculated by Vn = VRLn + 2α _2, terminates the vehicle speed estimating program I do.

On the other hand, if it is determined in step _S157 that the right rear wheel slip flag SFRR is zero, the process proceeds to step _S157 .
In _161, it is determined whether the left front wheel slip flag SFFL is zero, when the left front wheel slip flag SFFL is determined zero, in step S _162, the estimated vehicle speed value Vn
Vn = {(VFLn + VRRn) / 2} × α ₂
In this exit speed estimating program, step S _161, when the left front wheel slip flag SFFL is determined not to be zero, in step S _163, wherein the value Vn of the estimated vehicle speed; Vn = {(VRRn + VRLn ) / 2 Calculate by｝ × α ₂ and end this program.

Also, in step _S156 , the right front wheel slip flag
If the SFFR is determined to be zero, in step S _170, when the left front wheel slip flag SFFL it is determined whether the zero, left front wheel slip flag SFFL is determined to be zero In step _S164 , the estimated vehicle speed value Vn
Vn = {(VFRn + VFLn) / 2} × α ₂
Exit the estimated vehicle speed setting program, in step S _170, when the left front wheel slip flag SFFL is determined not to be zero, in step S _165, it determines whether the left rear wheel slip flag SFRL is zero I do. When the left rear wheel slip flag SFRL is determined to be zero, in step S _166, wherein the value Vn of the estimated vehicle speed; Vn =
{(VFRn + VRLn) / 2 } is calculated by × alpha ₂ ends the estimated vehicle speed program. On the other hand, in step S _165, when the left rear wheel slip flag SFRL is determined not to be zero, in step S _167, it is determined whether the vehicle is in a right turning traveling state, the vehicle is turning right If it is determined not the running state, in step S _168, the value Vn of the estimated vehicle speed formula; calculated by Vn = VRRn × α _2, and terminates the vehicle speed estimating program, in step S _167, the vehicle there when it is determined that the right turning traveling state, the value Vn of the estimated vehicle speed in step S ₁₆₉ wherein; ends the vehicle speed estimating program on calculated by Vn = VFRn × α _2.

Further, if it is determined in step _S155 that the slip wheel counting counter SN is not 2, the process proceeds to step S155.
_{At 171} , it is determined whether the slip wheel count counter SN is 3 or not. When it is determined that the slip wheel count counter SN is 3, at step S _172, whether the right front wheel slip flag SFFR is zero is determined. If the right front wheel slip flag SFFR is determined to be zero,
In step S _173, the value Vn of the estimated vehicle speed formula; Vn = VFRN
× calculated by alpha _3, and ends the vehicle speed estimation program. In step S _172, when the right front wheel slip flag SFFR is determined not to be zero, step S ₁₇₄
In, it is determined whether the left front wheel slip flag SFFL is zero, when the left front wheel slip flag SFFL is determined to be zero, in step S _175, the estimated vehicle speed value
The Vn formula; calculated by Vn = VFLn × α _3, ends the estimated vehicle speed setting program. In step S _174, when the left front wheel slip flag SFFL is determined not to be zero, in step S _176, the right rear wheel slip flag SFRR
Is determined to be zero, and a right rear wheel slip flag SFRR is determined.
If but which it is determined to be zero, in step S _177, the value Vn of the estimated vehicle speed formula; calculated by Vn = VRRn × α _3, and terminates the vehicle speed estimating program, also step S
In _176, when the right rear wheel slip flag SFRR is determined not to be zero, in step S _178, the value Vn of the estimated vehicle speed formula; calculated by Vn = VRLn × α _3, terminates the vehicle speed estimating program I do.

On the other hand, if it is determined in step _S171 that the value of the slip wheel count counter SN is not three, the vehicle speed estimation program ends.

Next, step S ₁₀₅ in the flowchart of FIG.
As shown in FIG. 7A, for example, the control mode setting program executed in
In _S179 , it is determined whether or not a four-wheel slip control flag CF4 to be described later is zero indicating that the vehicle is in a steady state. If it is determined that the four-wheel slip control flag CF4 is zero (YES), In step _S180 , it is determined whether or not the slip wheel counting counter SN is 1. If it is determined that the slip wheel count counter SN is 1 (YES), in step _S181 , the brake control execution flag EBF is set to 1 and the throttle control execution flag ETF is set to zero. in _182, it sets the target slip ratio TGTR for throttle control as described above to a constant TG2, in step S _183, sets the target slip ratio TGBR for the brake control in constant TG1, ends the control mode setting program.

If it is determined in step _S180 that the slip wheel counter SN is not 1, the process proceeds to step _S184.
In, it is determined whether the slip wheel number counter SN is 2, when the slip wheel counting counter SN is determined to be 2 in step S _185, whether the right wheel slip flag SFFR is zero Determine whether or not. When the right front wheel slip flag SFFR is determined to be zero, in step S _186, it is determined whether the left front wheel slip flag SFFL is zero, when the left front wheel slip flag SFFL is zero If it is determined, since the left rear wheel 21L and the right rear wheel 21R has occurred slip greater than a predetermined value with respect to the road surface, the brake control execution flag EBF in step S ₁₈₇ to 1 (brake control execution), also, Set the throttle control execution flag ETF to zero and set step S
_Proceeding to ₁₈₂ , the processes after step _S182 are sequentially executed in the same manner as described above, and the control mode setting program ends.

On the other hand, in step _S186 , the left front wheel slip flag
SFFL is when it is determined not to be zero, the left rear wheel slip flag SFRL determines whether a zero in step S _188. If it is determined that the left rear wheel slip flag SFRL is not zero, it means that the left front wheel 20L and the left rear wheel 21L have slipped by a predetermined value or more with respect to the road surface, and therefore, step _S189
In, the process proceeds to step S ₁₉₄ and sets the target slip ratio TGTR the set value TG2. Further, in step S _185, when the right front wheel slip flag SFFR is determined not to be zero, in step S _190, the right rear wheel slip flag SFRR
Is determined to be zero, and a right rear wheel slip flag SFRR is determined.
If but is determined in step S _191, when the left front wheel slip flag SFFL it is determined whether the zero, left front wheel slip flag SFFL is determined not to be zero,
Since the left front wheel 20L and the right front wheel 20R is that they generate slip greater than a predetermined value with respect to the road surface, in step S _192, the process proceeds to step S ₁₉₄ and sets the target slip ratio TGTR the set value TG3. Further, in step S _190, when the right rear wheel slip flag SFRR is determined not to be zero, since the right front wheel 20R and the right rear wheel 21R is that they generate slip greater than a predetermined value relative to the road surface, Step S
In _193, the process proceeds to step S ₁₉₄ and sets the target slip ratio TGTR the set value TG2. In step S _194, the brake control execution flag EBF and throttle control execution flag E
Set TF together 1, in subsequent step S _183, it sets the target slip ratio TGBR the set value TG1, ends the control mode setting program. Left Furthermore, when the left rear wheel slip flag SFRL is determined to be zero in step S _188, the left front wheel 20L and the right rear wheel 21R are caused to slip over the predetermined value, and in step S ₁₉₁ If it is determined that the front wheel slip flag SFFL is zero,
Since the right front wheel 20R and the left rear wheel 21L are slipping by a predetermined amount or more, in this case, the process proceeds to step _S187 , and the processes after step _S187 are executed in the same manner as described above to set this control mode. Quit the program.

On the other hand, if it is determined in step _S184 that the slip wheel counting counter SN is not 2, it is further determined in step _S196 whether the slip wheel counting counter SN is 3 and the slip wheel counting counter SN is determined. Is determined to be 3 in step _S197 .
It is determined whether or not the wheel simultaneous slip occurrence flag CF3 is zero. If it is determined that the three-wheel simultaneous slip occurrence flag CF3 is zero, it is determined in step _S198 whether or not the slip count counter SSN is three, and it is determined that the slip count counter SSN is not three. If the, in step S _199, sets the target slip ratio TGTR the set value TG2, the brake control execution flag EBF
And the throttle control execution flag ETF are both set to 1,
Setpoint target slip ratio TGBR in step S ₁₈₃ TG1
And exit this program. In addition, if it is determined in step _S197 that the three-wheel simultaneous slip occurrence flag CF3 is not zero, and if it is determined in step _S198 that the slip count counter SSN is 3 at the same time, the process proceeds to step _S200 . Above target slip rate
Set TGTR to the set value TG2 and set the brake control execution flag EBF
And sets the throttle control execution flag ETF together 1, set the 3-wheel simultaneous slip occurrence flag CF3 to 1, by performing the steps S ₁₈₃ similarly to the above, this program is ended.

On the other hand, in step S _196, when the slip wheel counting counter SN is not 3 determines in step S ₂₀₁ of FIG. 7B, further slip wheels number counter SN
Is determined to be 4 and a slip wheel counting counter is determined.
If it is determined that SN is 4, step
Proceed to S _202. Further, in another step S _179, when the four-wheel slip control flag CF4 is determined not to be zero also, the process proceeds to step S _202, in step S _202, in 2 four-wheel slip control flag CF4 is representative of a skid convergence state It is determined whether or not there is. If it is determined that the four-wheel slip control flag CF4 is not 2, then step S
_{In 203} , it is determined whether or not the four-wheel slip control flag CF4 is zero indicating a steady state. When four-wheel slip control flag CF4 is the steady state is determined to be zero, in step S _204, zero target slip ratio TGTR,
The brake control execution flag EBF is set to zero, the throttle control execution flag FTF is set to 1, and the four-wheel slip control flag CF4 is set to 1 indicating the slip convergence process, and the flow advances to step _S205 .
On the other hand, in step _S203 , the four-wheel slip control flag
If it is determined that CF4 is not zero, the process proceeds directly to step _S205 .

In step _S205 , as described above, the peripheral velocity values VFLn, VFRn, VRLn, and VRRn are added and divided by 4 to calculate the peripheral velocity average value VAV. Next step S ₂₀₆
, The total deviation value ε is calculated by the above equation; ε = (VF
Ln−VAV) ² + (VFRn−VAV) ² + (VRLn−VAV) ² + (VRRn
-VAV) ² , and in the subsequent step _S207 , it is determined whether or not the calculated total deviation value ε is equal to or smaller than a predetermined value Za. In step _S183 , the process directly proceeds to step _S183.
Operation (TGBR ← TG1) is described in steps S ₁₈₂ , S ₁₉₄ ,
This program is executed in the same manner as in _S199 and _S200 , and this program is terminated. On the other hand, if it is determined in step _S207 that the total deviation value ε is equal to or smaller than the set value Za, the process proceeds to step _S207 .
_{At 208} , the target slip rate TGTR is set to the set value TG1, and
The four-wheel slip control flag CF4 is set to 2, the built-in timer is started, and the measurement of the elapsed time T is started. Then, in the subsequent step _S210 , it is determined whether or not the elapsed time T is equal to or longer than a predetermined time length Tx.
If it is determined that the value is less than the predetermined value, step _S183 is executed in the same manner as described above, and the program ends. When it is determined that the elapsed time T is equal to or longer than the time length Tx, in step _S213 , the brake control execution flag EBF, the throttle control execution flag ETF, and the three-wheel simultaneous slip occurrence flag C
F3,4-wheel slip control flag CF4, and sets each of the slip wheel number counter SN to zero, and resets the internal timer, the step S ₁₈₃ ends the program after running in the same manner as described above. Also, the above step S
_{In step 201} , when it is determined that the slip wheel count counter SN is not 4, the steps _S213 and _S213 are also performed.
_S183 is executed in the same manner as described above, and returns to the original state (return).

On the other hand, in the target slip ratio correction program in the step S ₁₀₆ in the flowchart shown in FIG. 3, as shown in FIG. 8, the control operation after the start,
In step _S215 , a correction coefficient γ corresponding to the value of the number SN of slip wheels indicated by the slip wheel count counter SN is read from the internal memory. γ takes a large value when SN = 0 and is a constant that decreases as SN increases. In step S _216, is multiplied by a correction coefficient γ read in step S ₂₁₅ to the target slip ratio TGBR set new target slip ratio TGBR, also, in step S _217, the correction read in step S ₂₁₅ Set the coefficient γ to the target slip ratio TGTR
To set a new target slip rate TGTR and end the program.

Step S ₁₀₇ in addition flowchart of FIG. 3
The throttle control program, for example, as shown in FIG. 9, after the control operation starts, the throttle control execution flag ETF is determined whether the zero in step S _220, the throttle control execution flag ETF Is determined to be zero, in step _S221 , a normal throttle opening control program is executed and the program is terminated. On the other hand, in step S _220, if the throttle control execution flag ETF is determined not to be zero, in step S _222, it is determined whether the target slip ratio TGTR is zero, the target slip ratio TGTR is zero If it is determined that there is, in step _S224 , a throttle valve drive signal Ct is sent to the throttle actuator 13 in order to fully close the throttle valve 14, and this control program ends.

Further, in step S _222, when the target slip ratio TGTR is determined not to be zero, in step S _225, the opening degree θt of the throttle valve 14, a normal, which is set according to the amount of depression of the accelerator pedal 66 Target throttle opening Tk
It is determined whether it is below or not, and the opening degree θt of the throttle valve 14 is determined.
If NO is determined to be larger than the normal target throttle opening Tk, in step _S221 , a normal throttle opening control program is executed, and this program ends. In step _S225 , the throttle valve 14
If YES the opening θt is determined to be less than the normal target throttle opening Tk of, in step S _226, the front left wheel 20L by using the estimated vehicle speed value (vehicle speed) Vn, right front wheel 20R The average slip rate SAV of the left rear wheel 21L and the right rear wheel 21R that has caused a slip of a predetermined value or more with respect to the road surface is calculated, and in step _S227 , the target slip rate T
By subtracting the average slip ratio SAV from the GTR, the difference ΔS is calculated. Then, in order to match the average slip rate SAV the target slip ratio TGTR in step S ₂₂₈ that follows, to form a throttle valve drive signal (feedback control signal) Ct in accordance with the difference [Delta] S, the then sends it to the throttle actuator 13 Terminate the control program.

Further, the brake control program in step _S108 in the flowchart of FIG. 3 is executed after the start of the control operation, for example, as shown in the flowchart of FIG.
In step S _230, it is determined whether the brake control execution flag EBF is zero, the brake control execution flag EBF
If but which is determined to be zero, in step S _231, and stops the transmission of the drive signal Ca~Ch described above after the released state of each disc brake 35A~35D above, this program is ended . On the other hand, in step S _230, when the brake control flag EBF is determined not to be zero, the left front wheel slip flag SFFL determines whether a zero in step S _232. When the left front wheel slip flag SFFL is determined not to be zero, in step S _233, the left front wheel 20 using the value Vn of the estimated vehicle speed
Formula for the actual slip ratio SFL of L; SFL = (VFLn−Vn) / VFLn
Calculated by, in the following step S _234, in order to match the actual slip ratio SFL and the target slip ratio TGBR,
The drive signals Ca and Cb on the basis of a comparison of the actual slip rate SFL and the target slip ratio TGBR selectively delivered to solenoid valve 51 and 52, the process proceeds to step S _235. Step _S232
In, even if the left front wheel slip flag SFFL is determined to be zero, the process proceeds to step S _235. In step S _235, it is determined whether the right front wheel slip flag SFFR is zero, when the right front wheel slip flag SFFR is determined not to be zero, in step S _236, the estimated vehicle speed value
The actual slip ratio SFFR of the right front wheel 20R is calculated using Vn; SFR
= Calculated by (VFRn-Vn) / VFRn, the subsequent step S ₂₃₇
, The actual slip rate SFR and the target slip rate TGBR
In order to match the door, a drive signal Cc and Cd on the basis of a comparison of the actual slip rate SFR and the target slip ratio TGBR selectively delivered to solenoid valve 53 and 54, the process proceeds to step S _238. Also, in step _S235 , the right front wheel slip flag
Even when it is determined that SFFR is zero, step S ₂₃₈ is also performed.
Proceed to. In step S _238, when the left rear wheel slip flag SFRL it is determined whether the zero, the left rear wheel slip flag SFRL is determined not to be zero, step
In S _239, the actual slip rate SRL of the left rear wheel 21L formula using the value Vn of the estimated vehicle speed; calculated by SRL = (VRLn-Vn) / VRLn, in step S ₂₄₀ that follows, the actual slip rate
In order to match the SRL and the target slip ratio TGBR, and selectively transmits the driving signal Ce and Cf based on the comparison of the actual slip rate SRL and the target slip ratio TGBR the solenoid valve 55 and 56, the step S ₂₄₁ Proceed to. Further, in step S _238, even when the left rear wheel slip flag SFRL is determined to be zero, the process proceeds to step S _241. In step S _241, it is determined whether the right rear wheel slip flag SFRR is zero, when the right rear wheel slip flag SFRR is determined not to be zero, in step S _242, the estimated vehicle speed value Vn Is used to calculate the actual slip ratio SRR of the right rear wheel 21R; SRR = (VRRn
Calculated by -Vn) / VRRn, continues in step S _243, in order to match the actual slip rate SRR and the target slip ratio TGBR, actual slip rate SRR and the target slip ratio T
Based on the comparison with GBR, the drive signals Cg and Ch
And 58 to terminate the program. Further, in step S _241, when the right rear wheel slip flag SFRR is determined to be zero, step S ₂₃₁
Is executed in the same manner as described above, and the program ends.

On the other hand, in the power train control device of the first embodiment, as is clear from the above description of the configuration of the control unit 100, in addition to the slip control (traction control) described above, a torque distribution control (torque split control) is further performed. ) Means are provided at the same time, and can be combined with the slip control system as required.

First, in order to make the explanation easy to understand, control contents (basic program) of the torque distribution control system alone are described, and then control contents (correlation control program) combined with the above-described slip control are specifically described. I decided to.

11A and 11B show the control contents of the torque distribution control (torque split control).

First, after the control is started, in step _S301 , the arrival of the measurement timing for each predetermined clock time is determined. Parameters such as an accelerator opening, a boost pressure value, and a steering angle are measured based on signals from the sensors (step _S302 ).

Then, in step _S303 , the steering angle θs is set to a predetermined value θ.
It determines whether turning is b or more, in the case of not being swivel NO, the basic distribution ratio of torque distribution in step S _304, that is, the distribution ratio K _B between the front and rear wheels 0.5, and also the right and left distribution ratio Y
Is set to 0.5 so that it is even between the front, rear, left and right wheels.

On the other hand, the judgment result of step S ₃₀₃ is the case in the pivoted YES determines the longitudinal distribution ratio K _B in step S ₃₀₅ corresponds to the revolving state. The longitudinal distribution ratio K _B is a rear wheel 21L as K _B = 0.7 at the time of the corner entry, to increase the torque distribution amount for 21R, also during turning and evenly back and forth as K _B = 0.5, further K during corner exit _B = As 0.3, the amount of torque distribution to the front wheels is set to be large. This means that at the start of turning, the driving force on the rear wheel side is increased to improve turning performance, and at the end of turning, the driving force on the front wheel side is increased to improve straightness, resulting in good turning performance as a whole. In order to obtain

Next, the torque distribution to the left and right wheels during the turning is set in step _S306 , and the left / right distribution ratio Y is determined to increase as the lateral acceleration of the vehicle increases. Then, further steps S ₃₀₇ in lateral acceleration D _L is positive it is determined whether (left turn) or sets the turning flag F1 to 1 in the case of a left turn at the result YES (step S _308), NO In the case of turning right, the turning flag F1 is reset to 0 (step _S309 ).

Next, to determine the rear wheel distribution ratio K ₀ corresponds to the longitudinal acceleration D _FR in step S _310, the rear wheel 21L as the acceleration of the vehicle is increased to increase the torque distribution amount to 21R. And
According to the rear wheel distribution ratio K ₀ , the aforementioned step S ₃₀₄ or S _{305 is performed.}
The distribution ratio K _B before and after is corrected (step S ₃₁₁ ), and the distribution ratio K _F to the rear wheels is finally obtained. Then, control is performed such that the amount of torque distribution to the rear wheels increases during acceleration regardless of the presence or absence of turning.

In addition, step _S312 is performed based on the current engine generated torque Ps.
Is calculated, and the engine boost pressure value B,
Calculated based on throttle opening TVO or accelerator opening ACC. Then, in step _S313 , it is determined whether or not the longitudinal acceleration _DFR is smaller than 0.5 (equal value).
If a large torque distribution amount to the rear wheel side from the front wheel above, an acceleration flag F0 is reset to 0 in step S _314, while the determination result is the torque distribution to the front wheel side from the rear wheels is less than 0.5 in YES If the amount is large, as well as set to 1 acceleration flag Fo in step S _315, converts the longitudinal distribution ratio k at step S ₃₁₆ to a value greater than 1-k and 0.5.

Subsequently, the longitudinal distribution ratio in the step S ₃₁₇ of the 11B Figure K _F
The required torque Pr required to express the right and left distribution ratio Y is calculated. The calculation of the required torque Pr is based on the distribution torque Ps × K _F × Y for the wheel with the largest torque distribution.
Is obtained by multiplying by 4. It is determined whether or not the required torque Pr is smaller than the maximum torque _{PMax of the} engine (step
S ₃₁₈ ), when the judgment is YES that the engine torque has a margin,
The throttle opening is controlled to increase so that the engine torque becomes the required torque Pr (step _S319 ). Then, the acceleration flag F0 is determined whether it is set to 1 in step S _320, since at the time of acceleration is reset is load transfer to the rear wheels to 0, the front wheel side of the torque in Step S ₃₂₂ Control to apply braking force to the front wheels 20L, 20R so that the disc brakes 35A, 35B of the left and right front wheels 20L, 20R perform braking corresponding to half of the difference between the front and rear torque distribution, respectively, in order to reduce the torque I do. On the other hand, if the step S ₃₂₀ is the acceleration fluff F0 is determined in YES is set to 1, the front wheels 20L, since there is a load movement on the 20R side, the rear wheels 21L in step S _321, the 21R side Disc brakes 35 on left and right rear wheels 21L and 21R to reduce torque
In C and 35D, control is performed to apply a braking force to the rear wheel side so as to perform braking corresponding to a half of the difference between the front and rear torque distribution from the uniform distribution.

Further, in step _S323 , it is determined whether or not the turning flag F1 is set to F1 = 1. When the left turning is set to 1, since there is a load movement on the right front and rear wheels 20R, 21R, S left front and rear wheels 20L at _24, 21L side of the left front and rear wheels 20L so as to reduce the torque, the disc brake 35A of 21L, respectively so that the braking of the corresponding torque portion to half the difference of the left and right torque distribution from evenly distributed 35C To apply a braking force to the left wheel side. On the other hand, at the time of a right turn in which the acceleration flag F1 is reset to 0 with a NO determination in step _S323 , the left front wheel
20L, since there is a load shift to 21L side, step S ₃₂₅ in the right front and rear wheel side of the torque in order to reduce the right front and rear wheels 20R and, 21R of the brake 35B, to half the difference between the right and left torque distribution from equipartition respectively 35D Control is performed to apply a braking force to the right wheel side so as to perform the braking corresponding to the torque.

On the other hand, if the determination result in step _S318 is NO and the required torque Pr is larger than the maximum torque _{PMax of the} engine, the left / right distribution is stopped in step _S326 and the left / right distribution ratio Y is changed.
Calculate the required torque Pr at 0.5 and calculate the required torque P
It is determined whether or not r becomes smaller than the maximum torque _{PMax of the} engine (step _S327 ). When YES is determined to be smaller than the maximum torque _PMax , the throttle opening is controlled so that the engine torque becomes the required torque Pr (step _S328 ). Further, similarly to the step S ₃₂₀ to S _322, in accordance with the state of the acceleration flag F0 to the magnitude of the longitudinal distribution ratio Y in step S ₃₂₉ to S _331, the control to apply a braking force to the front wheels during acceleration On the other hand, during deceleration, control is performed to apply a braking force to the rear wheels.

Furthermore, the determination in step S ₃₂₇ is NO, indicating whether the requested torque Pr be stopped right and left allocation when the maximum torque P _MAx larger engines, the acceleration flag F0 is set to 1 in step S ₃₃₂ whether or determines, at the time of acceleration, which is reset to 0, while the maximum torque P _MAx the engine torque in step S _334, the braking force to the front wheel side to the braking torque corresponding to half of the torque increase Perform additional control. On the other hand, during deceleration when the acceleration flag F0 is set to 1, the engine torque is reduced to the maximum torque in step _S333.
In addition to P _Max , control is performed to apply a braking force to the rear wheel side so as to perform braking with a torque corresponding to half of the increased torque.

The change in the torque distribution amount was corrected to be equivalent to the wheel driving force by the gear ratio of the transmission, assuming that the front wheel side and the rear wheel side are each running at a driving torque of 50 kg · m, for example. The generated torque Ps of the engine is 100 kg · m. Here, in accordance with the acceleration state, a total of 30 kg
Assuming that the braking torque of m is applied and the driving torque lost by the braking torque is compensated for by an increase in the engine output, the required engine output torque Pr is 130 kg · m.
Becomes This is distributed equally 65 kg / m forward and backward, so the final distribution torque is 65-30 = 35 kg / m for the front wheels and 65 kg for the rear wheels.
Kg · m, and eventually the torque distribution ratio k of the rear wheel is 0.65.

<Correction to First Embodiment> (Correction to Slip Control) In the first embodiment, when the number of slip wheels is two, according to the combination of the slip wheels,
A first control mode in which only the brake control is performed and a second control mode in which the throttle control is performed in addition to the brake control are employed. In the second control mode, particularly, the traveling stability with respect to the vehicle is affected. The control mode is such that the target slip ratio is different between when the left or right front and rear wheels or the left and right rear wheels are slip wheels and when the other two wheels are slip wheels. However, the slip control device for a four-wheel drive vehicle according to the present invention does not always need to be so, for example, when the target slip rates in the brake control and the throttle control are set to the same value. The brake control and the throttle control are performed together, and the decrease in the drive torque acting on the slip wheels Ratio of by those with throttle control by the brake control, the slip control may of course also be configured to be performed according to the control mode which is different from depending on the combination of the two slip wheels.

Further, in the above-described embodiment, a specific slip rate value of a specific wheel for which a slip state equal to or more than a predetermined value is detected is calculated, and the calculated slip rate is made to match a set target value. For this purpose, the drive torque acting on a specific wheel is changed, but the slip control device for a four-wheel drive vehicle according to the present invention does not necessarily need to be so. When the value of the estimated vehicle speed is subtracted from the value of the peripheral speed of the specific wheel for which the slip state is detected, the slip amount for the specific wheel is calculated, and the calculated slip amount matches the target value. It may be configured to change the driving torque acting on a specific wheel in order to perform the driving.

Furthermore, in the above-described embodiment, the output torque of the engine during the slip control is configured to be variably adjusted by changing the throttle opening. However, the output torque is not necessarily required to be formed as such. For example, the air-fuel ratio, the ignition timing, the exhaust gas recirculation amount, the intake / exhaust valve opening / closing timing, the supercharging pressure, the fuel injection timing, and the like may be changed in place of the throttle opening to perform variable adjustment. Of course.

Furthermore, in the above-described embodiment, the power train control system is applied to a full-time type four-wheel drive vehicle that is always in a four-wheel drive state, but the present invention is not limited thereto. Needless to say, the present invention can be applied to a so-called part-time type four-wheel drive vehicle in which a four-wheel drive state and a two-wheel drive state can be arbitrarily and selectively set.

<Modification of Torque Distribution Method> In the configuration of the above embodiment, the braking force can be changed independently for each of the front, rear, left and right wheels, and the torque distribution for each wheel can be changed. It goes without saying that the braking force may be varied independently for the side and the rear wheels, and the torque distribution may be changed only for the front and rear wheels, or the torque distribution may be changed only for the left and right sides.

<Second Embodiment> Outline By the way, according to the control of the first embodiment, the slip control (traction control) and the torque distribution control (torque split control) of the drive wheels are each performed under the stability of the running state of the vehicle. As described in connection with the prior art, when these two controls are operated simultaneously, the following Interference problem.
The present inventors have categorized this interference problem into two types, and have devised control measures as a measure to improve each of them in the second type.
This is specifically proposed in the embodiment.

The first interference problem occurs when the need for torque split control occurs during slip control. For example, assume that the vehicle starts or turns on a road with low frictional resistance. As shown in FIG.12A, in such a case, the slip control by the occurrence of the slip and the torque split control by the uneven distribution of the load between the wheels are required at the same time. , The torque may be increased by the torque split control. In the above example, if the rear wheel slips at the time of starting, the torque is increased by the torque split control on the rear wheel to be slip-controlled, which makes it difficult to converge the slip state. That is, in this case, the superimposition control of the slip control and the torque split control causes inconvenience. On the other hand, if slippage occurs in the front wheels at the time of starting, increasing the torque distribution rate to the rear wheels by performing torque split control when performing slip control on the front wheels is not enough to improve startability. On the other hand, if turning is performed together with starting, there is an effect of improving turning performance at the beginning of turning. Further, a decrease in the front wheel torque due to the torque split control results in an early convergence of the slip. As described above, even when starting on a low-resistance road surface such as a snowy road, increasing the amount of distribution of the driving force by the torque split control itself, depending on the position where the slip occurs, and also the number of slip wheels, There are cases where the driving performance is good and cases where the driving performance is bad.

Therefore, in the second embodiment, a special control is devised so that the torque applied to the wheel on which the above-described slip control is being performed is not increased by the torque split control. The details of this control will be apparent from the description of the control procedure in FIG. 15 described below.

In the second embodiment, a further control is added. That is, the following must be considered as the second interference problem.

The second interference problem is when the necessity of the slip control occurs during the torque split control, contrary to the first interference condition. Now, for example, it is assumed that a turning operation is performed on a road having a large change in road surface resistance. In this case, as shown in FIG. 12B, when the lateral acceleration is detected during the right turn, the torque split control accompanying the load movement is executed, the engine output torque is appropriately distributed, and the outer wheels (FL, RL) are More torque is distributed to the motor. At this time, if the road surface changes and a slip occurs on the left rear wheel (RL) which is the outer wheel, as described in the first interference problem, the left rear wheel which is the slipping outer wheel The torque increase by the torque split control for the wheel RL must be stopped. However, simply stopping the torque split control causes the following inconvenience. That is, the wheels that are slipping are not necessarily all wheels. In the above example, at the moment when the slip occurs on the left rear wheel RL, a large amount of torque is distributed to the outside wheels (FL, RL), so that the torque applied to the inside wheels is small.
It is easy to stop the torque split control in order to reduce the applied torque to the outer wheel where the slip has occurred, but if the torque split control is stopped, the torque is evenly distributed, so until then On the inner wheels (FR, RR) to which only a small torque was applied,
Excessive torque rise occurs suddenly, and the inner wheels (FR, R
R) may cause a new slip. Or, even if a slip does not occur, the turning force given by the outer wheels of the turning corner that is slipping to the vehicle body and the turning force given to the vehicle body by the inner wheels that are given too much torque to turn. As a result, the turning performance of the vehicle is reduced, and the behavior of the vehicle body becomes unstable.

Therefore, in order to avoid the inconvenience caused by the second interference state, the second embodiment employs the following control measures. That is, when the torque split control is being executed, if a slip occurs on the wheels and the torque split control has to be stopped, that is, without stopping the torque split control, the torque split control is first stopped. Then, a wheel that gives a sudden increase in the applied torque is detected. For such a wheel, whether or not the wheel is actually slipping, if it is not generated, the slip control is performed as it is. This prevents a sudden increase in applied torque. The control means for avoiding the second interference state will be described later in detail with reference to the flowchart of FIG.

(Details of Power Train Control of Second Embodiment) FIGS. 13 to 19 show the details of the power train control operation of the second embodiment. In the control procedure of the second embodiment, FIG. 13 shows a main program, and FIGS. 14 to 19 show various subroutines used for control of the second embodiment. As described above, in both the torque split control and the slip control, the direct control target is the engine output (ie, the above-described throttle opening control signal Ct), and the brake control of each wheel (ie, the actuator control signal Ca). ~ Ch). Various signals and the like used in the control according to the second embodiment are shown in the following table (No. 2).
Table) shows this as a table.

That is, first, in step S400 of FIG. 13, it is determined whether or not the measurement timing of various input signals has come. In the case of YES at the measurement timing, the various input signals shown in Table 2 are read from the respective sensors. Further, in steps S402 and S403, slip determination and estimation of the vehicle speed are performed based on these input signals. Since the determination of the slip state in step S401 is the same as that of the first embodiment, the flowchart of FIG. 4 of the first embodiment is adopted as the control procedure. Then, in step S402, the slip state of each wheel is set to the flag SFF
The total number of slipped wheels is stored in the counter SN, and the number of simultaneously generated wheels is stored in the counter SSN in L, SFFR, SFRL, SFRR. Since the estimation control of the vehicle body speed Vn in step S403 is the same as that of the first embodiment, the flowchart of FIGS. 6A and 6B of the first embodiment is used as the control procedure.

(Slip Control Parameter Setting) Next, in step S404, various parameters used for the slip control of the present embodiment are set. The setting operation of this parameter is based on a slip state flag (SFFL or the like), a slip wheel coefficient counter SN or the like, and sets whether or not to perform brake control and throttle control for slip control in flags EBF and ETF, respectively. And holding and setting target slip rates (TGBR, TGTR). Monitoring of the four-wheel slip state is one of the operations in step S404. Since the details of the procedure of step S404 for setting various parameters used for the slip control are the same as those of the first embodiment, the control procedure is the same as that shown in FIG. 7A and FIG. The flowchart in FIG. 7B is cited.
Thus, according to the control parameter setting routine, the state of the brake control execution flag EBF and the throttle control execution flag ETF and the target slip ratio TGBR in the brake control for slip control are performed in the control mode shown in the control table of FIG. 2A, for example. The target slip ratio TGBR in the throttle control for slip control, etc.
SN, number of simultaneous slip wheels SSN, slip wheel position (SFF
R, etc.).

By the way, if a slip occurs on four wheels now (SN =
First, the slip convergence monitoring control 4) will be described in detail. 4
Each state of the control until wheel slip is eliminated from occurring, for example, followed by the value of the status counter CF _4. CF ₄ = 0 at the beginning of the four-wheel slip,
Thereafter, CF ₄ changes from 1 to 2 to 0.

Now, immediately after the slip occurs on the four wheels, in FIG. 7B,
Step S201 → Step S202 → Step S203 → Step
Proceeding to S204, EBF = 0 is set in this step S204 to stop the brake control. Also, although throttle control is performed, EF is used to fully open the throttle valve.
T = 1 and TGTR = 0. In step S204, the status indicating that the control is started for converging the four-wheel slip state is stored as CF ₄ = 1.

In step S205, the average vehicle speed VAV is estimated from the following equation,
In step S206, the peripheral speeds of the four wheels (VFL, VFR, VRL, VR
Calculate the variation ε of R).

Until it is detected that this ε has become equal to or less than the predetermined threshold value Za, the control procedure is step S201 → step S202 → step S203 → step S205 → step S206 → step S2
07 → Step S183 is repeated, during which CF ₄ = 1, EBF = 0, ETF = 1, TGTR = 0, TGBR = TG ₁ are maintained.

Eventually, the slip convergence between the wheels, the circumferential speed of the dispersion epsilon is detected in step S207 and becomes Za (ε ≦ Za), in step S208, the target slip ratio TGTR throttle control in TG ₁ change (TGTR = TG _1), to tend to open slightly the throttle from fully open. Also, to start the timer for the period Tx, to indicate that the timer has started
Change CF ₄ to 2.

Until this timer has timed out in step S210, the control procedure is step S201 → step S201.
Steps S202 → Step S210 → Step S183 are repeated, during which CF ₄ = 2, EBF = 0, ETF = 1, TGTR = TG ₁ , and TGBR = TG ₁ are maintained.

Eventually, when the preset time Tx elapses so that the four-wheel slip state will sufficiently converge, step S2
In _{13, CF 4, CF 3,} EBF, EFT, SN, SFFL, SFFR, SFRL, SFRR = 2, E
Reset BF = 0 and ETF = 1.

Returning to the description of FIG. In step S405, step S4
The target slip rates TGTR and TGBR set in 04 are corrected. That is, by multiplying TGBR and TGTR by a coefficient γ that changes in accordance with the value of the slip wheel number SN, TGBR = TGBR × γ (step S216) TGTR = TGTR × γ (step S217) Is corrected to the target value of the slip rate suitable for

(Torque Split Control Parameter Setting) Details of the torque split control parameter setting routine in step S406 are shown in FIG. Step S4
At 23, it is determined from the excessive steering signal θs whether the vehicle is currently turning.

If not turning, at step S424, a basic torque distribution ratio K _B to 2 wheel 0.5 after, sets the torque distribution ratio Y to the right of the 2 wheels 0.5. That is, the distribution ratio is determined so that the torque distribution between the front, rear, left, and right wheels is uniform.

On the other hand, if it is determined that the vehicle in the step S423 is turning, at step S425, in order to increase the rear wheel torque to the turning start that requires turning property, a basic torque distribution ratio K _B 0.5, straight At the end of a turn that requires good performance, the basic torque distribution ratio K _{B is set} to 0 in order to increase the driving force on the front wheel side.
Set to 3. In this way, turning performance is enhanced by selecting an appropriate rear wheel torque distribution ratio at each stage of turning.

In addition, for the right and left wheels, the torque distribution ratio (absolute value) Y to the right wheel is set to be larger than 0.5 as the acceleration D _L becomes larger in accordance with the absolute value | D _L | of the lateral acceleration D _L. Set to quantity. Even torque distribution ratio Y of the right wheel as an absolute value, whether right turn or left turn according to the sign of the lateral acceleration D _L, no problem remembers the flag F _1. That is, in the case of a left turn as the acceleration D _L is positive, that is, if you need to allocate more torque to the right wheel, "1" to the flag F ₁ in step S428, becomes acceleration D _L is negative when turning right, that is, if you need to allocate a lot of torque to the left wheel, "0" is set in the flag F ₁ in step S429.

Thus, the torque distribution ratio Y to the basic torque distribution ratio Ka and right wheel to the rear wheels is calculated in step S430~ step S436, it determines the final allocation ratio K _F of the rear wheel torque. That is, in step S430, determines a correction coefficient Ko in accordance with the longitudinal acceleration D _FR, at step S431, the final distribution ratio
K _F is calculated from K _F = (K _B × Ko) /0.5. Molecular 0.5 is to normalize the contribution due to the correction Ko for K _F. By comparing the K _F and 0.5, can body to determine whether in or the non-accelerated during the acceleration. In step S432, an engine generated torque Ps is determined based on the boost pressure B of the engine, the throttle opening θt, or the accelerator opening θa.

Steps S433 to S436 are procedures for performing acceleration determination. In step S433, acceleration and deceleration are determined by examining the sign of the longitudinal acceleration, and if non-acceleration ( _DFR > 0) is determined, a flag is set in step S435 to indicate that non-acceleration is being performed. Fo is set, and if it is determined that the vehicle is accelerating (D _FR <0), the flag Fo is reset in step S434 to store that the vehicle is accelerating.

Incidentally, wheel distribution ratio K _F and the right wheel distribution ratio Y after being obtained in the control procedure of FIG. 14 are not necessarily to "correct" designation, at this stage, K _F, Y, respectively, the front wheel distribution ratio, It may also include the left wheel distribution ratio. When calculating K _F and Y, the steps in FIG.
S430, respectively in step S426, the absolute value of the longitudinal acceleration D _FR and, in absolute value and the correction constant Ko of the lateral acceleration D _L, because determines the Y. Correction for K _F and Y to accurately reflect the rear wheel distribution ratio and the right wheel distribution ratio is performed in steps S500 to S503 in FIG. 19 described later.

Thus, various parameters for the torque split control (rear wheel torque distribution K _F , right wheel torque distribution Y)
The determination is appropriately made according to the determination as to whether or not the vehicle is turning, whether the vehicle is turning at the beginning, during the turning, or at the end of the turning.

(Slip Control, Torque Split Control) Next, based on the control procedure shown in steps S407 to S416 in FIG. 13 and the various control parameters determined in FIGS. Slip control,
A specific control process in which the torque split control is actually performed will be described in detail.

As described above, each of the torque split control and the slip control according to the present invention at the embodiment level includes the torque control (throttle control) and the brake control of the engine. Engine torque control for the torque split control and the slip control is executed in step S415 in FIG. 13, and details of step S415 are shown in FIG. In FIG. 17, steps S521 to S526 are engine torque control for torque split control.
S527 to step S532 are engine torque control for slip control. On the other hand, the brake control for the torque split control and the slip control is executed in step S416 in FIG. The details are shown in FIG. In FIG. 18, step S480 (the details of which are shown in FIG. 19) indicates brake control for torque split control, and steps S481 to S484 indicate brake control for slip control. And the following Table 3 shows the mutual relationship between the above controls.

Steps S407 to S414 in FIG. 13 correspond to parameters used in engine torque control and brake control for each of the torque split control and the slip control (these parameters are set before step S406). This is a procedure for correcting the occurrence of the two interference states described above. In particular, control for coping with the first interference state is mainly shown in the flowchart of FIG. 16, and control for coping with the second interference state is mainly shown in FIG. The following Tables 4 and 5 respectively divide the above two interference states into more detailed cases and briefly describe the coping control for each case.

Further, according to the attached drawings, steps S407 to S4
Up to 16 will be described in detail.

First, in step S407, it is determined whether torque split control is necessary. This is the rear wheel torque distribution ratio K _F
It can be recognized by judging whether or not the right wheel torque distribution ratio Y is 0.5. If it is determined that K _F = Y = 0.5, the process proceeds to step S415. Step S415 is the engine torque control, the details of which are shown in FIG.

(Case where Torque Split Control is Not Required) Here, the engine torque control in FIG. 17 in the case where it is not necessary to perform the torque split control will be described. First, in step S520 in FIG. 17, it is determined whether or not the throttle control execution flag ETF is 0. EFT
= 0, that is, a case where it is not necessary to perform throttle control for slip control. When EFT = 0, as shown in FIG. 2A, for example, the number of slip wheels is one. In such a case, the process proceeds to step S521, and first, the required torque Pr of the driver is calculated. this
Pr is an engine generated torque corresponding to the accelerator opening θt, the boost pressure B, and the like. Next, in step S522, the necessary torque Ps for performing the torque distribution determination is calculated.

Pr = 4 · Ps · K _F · Y When K _F = Y = 0.5 where torque split control is not performed, Pr = Ps.

As already described with reference to the flowchart of FIG. 11,
At present, K _F and Y do not represent the rear wheel torque distribution ratio and the right wheel torque distribution ratio, respectively. That, K _F, if there is uneven rear wheel torque distribution ratio and the front wheel torque distribution ratio is meant the larger distribution rate. Y
Also means the larger of the right wheel distribution ratio and the left wheel distribution ratio. Therefore, when torque split control is substantially performed (when K _F ≠ 0.5 and Y ≠ 0.5), Pr =
4 · Ps · K _F · Y means the maximum torque required for performing the torque split control and the slip control.

Next, in step S523, the torque required for the engine
Examine the magnitude of Pr and the maximum torque _PMax that can be generated by the engine. When the required torque Pr is less than P _MAX (Pr <P
_MAx ), since the engine has room, the throttle opening to generate a torque corresponding to this Pr is set in step S5.
25 or the required torque Pr is _{equal to} or greater than P _MAx (Pr ≧ P
_MAx ), it is impossible for the engine to output more than _PMax , so in step S524, Pr is changed to _PMax , and then the throttle opening is set to generate a torque corresponding to this _PMax. It is calculated in step S525. In step S526, a control signal Ct corresponding to the opening is output to the throttle actuator 13.

Next, the case where engine torque control for slip control is performed in step S520 (ETF = 1) will be described. Such a case is, for example, a case where a slip occurs only in the left and right front wheels. In this case, the process proceeds to step S527 to check whether the value of the target throttle slip ratio TGTR is zero. When it is zero, as shown in FIG. 2A,
This is the case where slippage occurs on the four wheels. If TGTR is zero, the throttle valve is fully closed in step S528. If TGTR is not zero, the process proceeds to step S530, and the average value SAV of the slip ratio of each wheel is calculated. For example, when a slip occurs between the left front wheel and the right front wheel, the calculation is performed as SAV = 1/2 {(VFLn-Vn) / (VFLn + VFRn-Vn) / VFRn}. Next, in step S531, a deviation ΔS between the average slip ratio SAV and the target slip ratio TGTR by the throttle control is calculated from ΔS = TGTR−SAV. In step S532, a throttle valve control signal Ct corresponding to ΔS is output to the actuator 13. When the control signal Ct is output to the actuator 13, the opening degree of the throttle valve is controlled in accordance with the signal Ct, the engine torque is reduced, and as a result, the wheel slip ratio is controlled.

The above is the description of the engine torque control (FIG. 17).
That is, steps S521 to S526 are engine torque control for torque split control, and step S527 is performed.
Step S532 was engine torque control for slip control.

Returning to the description of the flowchart in FIG. Step S415
When the torque control is ended, the brake control in step S416 is executed. Details of the brake control are shown in FIG. First, in step S480, brake torque TBST (TBST) for torque split control for each wheel
FR, TBSTFL, TBSTRR, TBSTRL) are calculated. The details of this calculation routine are shown in FIG.

Steps S500 to S503 in FIG. 19 are introduced because the braking force (torque) for torque split control to be applied to each wheel is defined in step S508 by the following equation.

TBSTFR = Ps / 4− ｛Ps · (1-K _F ) · Y｝ TBSTFL = Ps / 4− ｛Ps · (1-K _F ) · (1-Y)｝ TBSTRR = Ps / 4− ｛Ps · K _F · Y｝ TBSTRL = Ps / 4− {Ps · K _F · (1-Y)} Ps / 4 of the first term on the right side of each of the above equations is one of the engine torques Pr requested by the driver. This is the torque assuming that it is distributed to the wheels on average. Also, the second
The term is the amount of torque to be distributed to each wheel according to the parameters K _F and Y in FIG. By subtracting the second term from the first term, the braking force TBST for each wheel for the torque split control is calculated as in the above equation.

However, in the calculation of K _F , Y in FIG. 14, it is processed as a positive number of K _F , Y. For example, if the cornering last corner escape, to indicate that it should often distribute torque to the front wheels, K _F is should be smaller than 0.5, at step S430 in FIG. 14, the front-rear direction Acceleration
Since the correction constant K _F is determined by the absolute value of D _FR , for example,
Even in the same state, the value of K _F is larger than 0.5 in step S.
It is calculated by 432. The situation is the same for the right wheel distribution ratio. Therefore, in steps S500 to S503 in FIG. 19, it is necessary to correct K _F and Y so that the distribution ratio is correctly represented in the acceleration state and in the turning direction.

Based on the corrected torque distribution ratio, a braking force for torque split control is determined by the procedure starting from step S504.

That is, in step S504, first, it is confirmed that the torque Pr required for the engine during the current operation is smaller than the maximum torque _PMax that can be generated by the engine, that is, it is possible to perform torque increase control. . Pr ≧ P
_In the case of _MAx , that is, if there is still enough engine output, the process proceeds to step S508, where TBSTFR, TBSTFL, TBSTRR, TBS
Calculate TRL.

On the other hand, if it is determined in step S501 that Pr> P _MAx ,
Proceed to step S505. Here, in order to equalize the torque distribution ratio between the right and left wheels, the distribution ratio Y is set to Y = 0.5, and the engine required torque Pr = 2 · Ps
- to calculate the K _F. Then, in step S506, it is determined again whether the torque Pr required for the engine in a state where the left-right distribution ratio is equal is smaller than the maximum torque _{PMax of the} engine.

If it is determined in step S506 that the torque distribution to the left and right wheels is equal and the required torque Pr of the engine is not smaller than the maximum torque _{PMax in} step S506, then in step S507, K _F = {(P _MAx −Ps) / (Pr−Ps)} · (K _F −0.5) +
Calculate with 0.5. What this equation means is the distribution rate K _F
The value of K _F, the difference between the engine torque demand Pr and generated torque Ps (Pr-Ps), the ratio of the difference between the torque generated Ps of the maximum torque of the P _MAx and the engine (P _MAx -Ps) Based on this, it is reduced by 0.5.

Returning to the description of FIG. Upon completion of the calculation of the braking force in step S480, the process proceeds to step S481. Step S481
In ~ 484, the braking force TBTR (TBT
RFL, TBTRFR, TBTRRL, TBTRRR) are calculated. Next, steps S481 to S484 will be described in detail.

In step S481, it is determined whether or not the brake control for the slip control should be performed based on the value of the flag EBF. When the brake control is not performed (EBF = 0), in step S484, TBTRFL = 0, TBTRFR = 0, TBTRRL = 0,
TBTRRR = 0. When performing brake control (EBF = 1),
Proceeding to step S482, a correction value MBTR is calculated. That is,
If a is a predetermined constant, MBTRFL = a. (SFL-TGBR) MBTRFR = a. (SFR-TGBR) MBTRRL = a. (SRL-TGBR) MBTRRR = a. (SRR-TGBR) Further, in step S483, the braking force TBTR is updated.

TBTRFL = TBTRFL + MBTRFL TBTRFR = TBTRFR + MBTRFR TBTRRL = TBTRRL + MBTRRL TBTRRR = TBTRRR + MBTRRR Thus, the braking force TBTR for slip control is calculated.

Then, the process proceeds to step S485, in which the braking force TBST for torque split control and the braking force TBTR for slip control are set.
Are compared. If TBST> TBTR, the brake control is performed in step S486 such that the slip control is prioritized so that the braking force of each wheel becomes the calculated value TBTR. Conversely, when TBST> TBTR, the torque split control is given priority, and the braking force of each wheel is set to TBST.
Brake control is performed so as to be ST.

Step S485 indicates that the magnitude relationship between TBST and TBTR is determined for each wheel. As a result, while the brake control for torque split control is performed between different wheels, the other wheel is simultaneously However, brake control for slip control may be performed.
For example, TBSTFR> TBTRFR is determined for the right front wheel, brake control for control is performed on the right front wheel, and TBSTRR> TBTRRR is determined for the right rear wheel. Brake control for slip control is performed on the rear wheels.

(When only the torque split control is executed) When only the torque split control is executed, the slip wheel number SN is zero, and the brake control and the torque control for the slip control are not performed.
BF = 0. In addition, K _F ≠ 0.5 and / or Y ≠ 0.5 in accordance with the uneven load distribution applied to each wheel. Therefore, when the process proceeds to step S407 after the various parameters are set in steps S404 and S406, a NO determination is made here. Next, step S408
So, to find out if the number of slip wheels is increasing,
To determine the establishment of SN> SN _T. Here, when the SN _T is the number of the slipping wheel is increased, a register for temporarily comparing that number. Step S409 to Step
S411 is a procedure for detecting the occurrence of the second interference state. For now, assuming there is no slip,
In step S408, a determination of NO is made, and the process does not proceed to step S409 but proceeds to step S411 and step S412. Also, since it is assumed that ETF = 0 now, YES in step S412
Is determined. Then, a determination routine (see FIG. 16 for details) for determining whether to stop the torque distribution in step S414 is executed.

In the control means of FIG. 16, the slip determination flag (SF
FR, etc.) is zero, so that in this subroutine substantially nothing is performed, the process returns to step S415 and step S416 in FIG. 13, and these procedures are sequentially executed. That is, in the engine torque control shown in FIG. 17, steps S521 to S526 are executed, and in FIG. 18, the braking force of the torque split control is calculated in step S480. On the other hand, since EBF = 0, TBTR = 0 in step S484, so that the brake control for torque split control in step S487 is performed.

(Case Where Second Interference State Occurs) For convenience of explanation, a case where the second interference state occurs will be described first. As described with reference to FIG. 12B, when the occurrence of slip wheels is detected during the execution of the torque split control, the second interference state immediately stops the torque split control and then executes the slip control. A situation in which it is necessary to determine whether or not it is acceptable.

As an example, as shown in FIG. 12B, it is assumed that a slip occurs between the outer left front wheel and the left rear wheel during a right turn.

In such a case, step S4 in the flowchart of FIG.
02, in steps S404 and S406, the parameters must be determined as follows: SFFL = SFRL = 1 SFFR = SFRR = 0 SN = 2 EBF = ETF = 1 TGTR = TG ₂ × γ TGBR = TG ₁ Also, in step S406 (FIG. 14), for example, parameters K _F = 0.5 and Y = 0.3 F ₁ = 0 are set to indicate a right turn. Further, according to the torque split control (Step S508; FIG. 19), TBSTFR = TBSTRR = 0.1Ps TBSTFL = TBSTRL = −0.1Ps

Next, since the torque split control is being performed, a NO determination is made in step S407. Also, SN
> Because it is SN _T, determination of YES at step S408 it has been made. Proceed to step S409. In step S409, SN _T
Is updated, and then a slip flag reset routine (FIG. 15) in step S410 is performed.

That is, since SFFR = SFRR = 0, it is the two right wheels that may be subjected to the parameter setting change in steps S440 to S451 in FIG. That is, for the right front wheel, the process proceeds to step S440 and step S441, and (1-K _F ) · Y = 0.15 is calculated, and the determination in step S441 is YES. Therefore, in step S442, SFFR = 1, TBTRFR = TBSTFR = 0.1Ps is executed. What this step S442 means is
The brake power TBSTFR to be applied to the right front wheel for torque split control and the brake power TBTRFR to be applied to the same wheel for slip control are regarded as slipping wheels that are not actually slipping.
Is to be considered. The same operation as described above is performed in steps S447 to S448 for the right rear wheel that is not actually slipping.

Thus, when spin is detected on any of the wheels while the torque split control is being performed, first, the torque split control distributes a torque smaller than 25% of the engine output torque. For such a wheel, the brake TBST for the torque split control set in the previous control cycle is changed to the braking force for the slip control for such a wheel. This is the content of the slip flag resetting routine in step S410.

Upon completion of the calculation in step S410, next step S412
Then, it is checked whether the engine torque control for the slip control should be performed (ETF = 1).

In the presently described example, slip is applied to the left front wheel and the left rear wheel such that the engine torque control and the brake control should be performed together (ETF = EBF = 1) for the slip control. It is assumed that this has occurred. Therefore, because ETF = 1, control proceeds from step S412 to step S413, where K _F = Y = 0.5
By doing so, the torque split control is stopped. That is, TBST calculated in step S508 becomes zero due to K _F = Y = 0.5. Thus, a case where a slip occurs during the torque split control as shown in Table 5 will be described as an example. From the table of FIG. 2A, when only one wheel has slipped, only the brake control is performed (EBF = 1) and the engine torque control is not performed (ETF = 0) regarding the slip control. In this case, in step S410 (FIG. 15), the distributed torque is 25
Regardless of whether the wheels are slipping or not, the slip flag (SFFR, etc.) is set and TBTR = TBST, and the wheels to be slip-controlled have brake control for slip control. Of the brake control for the torque split control and the brake control for the torque split control, the brake control for the larger brake force (step S485; FIG. 18) is performed. Here, the "wheel to be subjected to slip control" in Table 5 refers to a wheel for which a slip is first detected and a wheel for which the slip flag is forcibly set. In other words,
Torque split control continues. This control is the content of (a) in Table 5.

Next, the meaning of (c) in Table 5 is as follows. When the engine torque control is not performed in the slip control (ETF = 0), that is, when only the brake control is performed, the control shown in FIG. 16 is performed in step S414, and the slip flag is set to one of the four wheels. Is set,
And when the engine torque applied to the wheel exceeds 25% of the total engine torque, the torque split control is stopped. However, as shown in (c) of Table 5, even if one of the wheels to be subjected to slip control has a wheel to which a torque exceeding 25% is applied and the torque split control is stopped, For the wheels, as described above, TBTR is set to the previous TBST, while TBTR is set to 0 in step S508, so that the braking force for slip control is maintained.

(Occurrence of First Interference State) The first interference state means that a slip has occurred, slip control is being performed on the slip wheel, and at that time, torque split control is being performed. When the torque increase control is to be performed on the slip wheels, the torque split control is to be stopped. There are two modes ((b) and (c)) for stopping the torque split control, as shown in Table 4.

An example of the control shown in (b) of Table 4 is shown in FIG. 20B. When the slip control is performed on the left front wheel FL only by the brake control (FTF = 0) and the torque applied to at least one of the slip control target wheels (FL) may exceed 25%, The torque split control is stopped. Since the slip control target wheel is a wheel that is slipping or has a risk of slipping, if even a large torque may be applied to any one of these wheels, for example, the engine torque control is not executed. Even in the case (ETF = 0), the torque split control is stopped to suppress the slip state early.

In FIG. 20, the wheels are hatched to indicate that the wheels are subject to slip control. In addition, 20A
In FIG. 20B, the left rear wheel RL is forcibly regarded as a slip wheel in the slip flag resetting routine of FIG.

(C) in the table corresponds to FIG. 20C. When the engine torque control is executed in the slip control (ETF = 1), what is the torque distribution ratio by the torque split control? Even if there is, the torque split control is stopped entirely. The control of (a) in Table 4 is as follows:
This corresponds to FIG. 20A. In the case where the torque split control becomes necessary during the slip control, the torque split control is executed as it is in response to the request. In this case, all the torques applied to all the slip control target wheels are less than 25%. In the example of FIG. 20A, the torque applied to the slip control target wheels (FL, RL) is all less than 25%. In such a case, since there is no risk of generating a new slip or promoting the slip until that time, the torque split control is executed. In the control of (a) in Table 4, even if a torque exceeding 25% is applied to the wheels other than the wheels to be subjected to the slip control, it is considered that no slip problem will occur. Execute control.

Table 4 shows the step numbers that are the points where the respective controls (a), (b), and (c) are executed.

In the control mode of (a) in Table 4 in which the torque split control is executed, the control in FIG.
At 42 mag, TBTR = TBST is set. As a result, in the forced mode shown in Table 4 (a), the brake control for the slip control and the brake control for the torque split control coexist.
By step S485 in the drawing, the brake control of the larger braking force of TBTR and TBST is adopted.

<Modifications of the Present Invention> Needless to say, the present invention can be variously modified without departing from the gist thereof.

For example, in the first and second embodiments, as a means for controlling the torque distribution, a method in which the braking force of each of the disc brakes 35A to 35D is made variable is adopted. However, the means is not limited thereto. Rather, for example, friction clutches are provided on the left and right output shaft portions of the front and rear differential mechanisms 25 and 27 and the propeller shafts 24 and 26, respectively, and control is performed by individually controlling their fastening forces. Needless to say, it may be done.

The invention of the present application can be further modified, and it is needless to say that modifications and equivalents thereof are included in the scope of the present invention, and the invention of the present invention should, of course, be determined by the above-mentioned claims.

[Brief description of the drawings]

FIG. 1 is a control system diagram showing an overall configuration of a control system of a power train control device according to first and second embodiments of the present invention, and FIGS. 2A and 2B are diagrams of the first embodiment. FIG. 3 is a control chart showing the number of slip wheels and the contents of control of the slip control and a time chart of the control operation.
FIG. 4 is a flowchart showing a main routine of a slip control (traction control) system of the apparatus of the embodiment, FIG. 4 is a flowchart of a subroutine showing a slip determination operation of the slip control system, and FIG. 6A and 6B are flowcharts of a subroutine showing a detection operation, and FIGS. 6A and 6B are flowcharts of a subroutine showing a vehicle speed estimation operation of the slip control.
7A and 7B are flowcharts of a subroutine showing a control mode setting operation of the slip control, FIG. 8 is a flowchart of a subroutine showing a target slip ratio correcting operation of the slip control, and FIG. 9 is a slip control thereof. Is a flowchart of a subroutine showing the throttle control operation of FIG.
FIG. 10 is a flowchart of a subroutine showing a brake control operation of the slip control. FIGS. 11A and 11B are torque distribution control (torque split control) of the above-described embodiment.
The system flow chart, FIG. 12A and FIG.
FIG. 13 is an explanatory diagram illustrating a problem to be solved by the embodiment;
FIG. 14 is an overall view of a main flowchart of a control procedure according to a second embodiment of the present invention, FIG. 14 is a flowchart of a torque split control parameter setting subroutine in the second embodiment, and FIG. 15 is a flowchart in the second embodiment. FIG. 16 is a flowchart of a subroutine for resetting a slip flag, FIG. 16 is a flowchart of a subroutine for determining whether to stop the torque distribution in the second embodiment, FIG. 17 is a flowchart of a subroutine for controlling the engine torque in the second embodiment,
FIG. 18 is a flowchart of a brake control subroutine in the second embodiment, FIG. 19 is a flowchart of a brake force calculation subroutine in the second embodiment, and FIG.
FIG. A, FIG. 20B, and FIG. 20C are explanatory diagrams for explaining a second interference state in the second embodiment. 10… Car body 11 …… Cylinder 12 …… Engine 13 …… Throttle actuator 14 …… Throttle valve 20L …… Left front wheel 20R …… Right front wheel 21L …… Left rear wheel 21R …… Right rear wheel 22 …… Transmission 23 …… Center differential mechanism 30 …… Brake control unit 35A to 35B …… Disc brake 100 …… Control unit

Continuation of front page (56) References JP-A-1-114523 (JP, A) JP-A-1-141126 (JP, A) JP-A-2-20432 (JP, A) Patent 2615806 (JP, B2) Patent 2615085 (JP, B2) Patent 2670284 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) B60K 41/00-41/28 F02D 29/00-29/06 B60T 7/12- 7/22 B60T 8/32-8/96 B60K 17/28-17/36 F02D 41/00-41/40

Claims (2)

(57) [Claims] In a power train control device for controlling transmission of engine output torque to wheels as a whole, output torque from an engine is independently distributed to respective wheels while variably controlling the distribution amount. Torque distribution control means, slip control means for detecting a slip state of each wheel, and slip control so that the detected slip amount of the slip wheel is equal to or less than a predetermined level. Slip control is performed by the slip control means. A torque determining means for determining whether or not the torque distributed to the wheel is increased when the torque distribution controlling means further acts on the wheel being controlled; and an output of the torque determining means. Therefore, when the torque distributed to the slip control target wheel is increased, at least the distribution to the slip control target wheel is increased. By controlling the slip control means or torque distribution control means to reduce the torque,
A power train control device comprising: a torque suppression unit that suppresses a transmission torque to a slip control target wheel. 2. A power train control device for totally controlling transmission of engine output torque to wheels, wherein the output torque from the engine is independently distributed to each wheel while variably controlling the distribution amount. Torque distribution control means, slip control means for performing slip control so that the slip amount of the wheel is equal to or less than a predetermined level, first detection means for detecting a wheel to be controlled by the slip control means, When the output of the first detecting means is received and the torque distribution control means is operating,
Second detecting means for detecting that the slip control is about to be performed on the wheel to be controlled by the slip controlling means, and receiving an output of the second detecting means and distributing the output to the wheel to be slip controlled. Torque determining means for determining whether the torque to be performed is equal to or greater than a predetermined value; and receiving the output of the torque determining means, the torque transmitted to the slip control target wheel is equal to or greater than a predetermined value. The power train control device further comprises a torque suppression unit that suppresses an increase in torque to the slip control target wheel.