JPH0281720A - Slip control device for four-wheel drive vehicle - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a slip control device for a four-wheel drive vehicle that performs control to suppress the slip of each wheel on a road surface in a four-wheel drive vehicle.

(Prior art) When the wheels slip on the road surface on a large scale when the vehicle is running, grip running is not performed;
In such a case, the slip of the driving wheels on the road surface should be suppressed by activating the vehicle's brake device or reducing the engine output, as appropriate driving characteristics may not be obtained. A slip control device that performs control is known.

In order to suppress the slip of the driving wheels on the road surface using such a slip control device, it is necessary to detect a state in which the driving wheels are slipping more than a predetermined amount on the road surface, or to suppress the slip on the road surface more than a predetermined amount. In order to set a target circumferential speed or a target slip rate for the driving wheels, it is required to detect the vehicle speed. In a two-wheel drive vehicle where only the front wheels or rear wheels are driven, vehicle speed can be relatively easily detected based on the circumferential speed of the driven wheels, which rarely cause slip on the road surface. In a four-wheel drive vehicle in which both the rear wheels and rear wheels can be driven, when the vehicle is in the four-wheel drive state, there is no driven wheel, so detection is impossible. It will be considered difficult.

In order to eliminate such inconveniences associated with four-wheel drive vehicles, for example, Japanese Patent Application Laid-Open No. 62-289429 discloses that the circumferential acceleration of each wheel in a four-wheel drive vehicle is determined, and based on the circumferential acceleration. The four-wheel drive system detects a state where each wheel is slipping more than a predetermined amount with respect to the road surface, and estimates the vehicle speed based on the minimum circumferential speed of each wheel. A vehicle slip control device has been proposed.

In such a slip control device, if the number of wheels that are slipping more than a predetermined value detected based on the circumferential speed of each wheel is, for example, three or less, the acceleration performance and running distance of the vehicle may be affected. In order to prevent the drive characteristics such as performance from decreasing, the brake system applies braking force only to those wheels that are slipping more than a predetermined amount with respect to the road surface. If this occurs, it has a significant impact on the running stability of the vehicle, so in addition to controlling the brake system to apply braking force to each wheel, control is also performed to reduce the engine output. .

(Problem to be Solved by the Invention) In a four-wheel drive vehicle, when all the wheels are slipping more than a predetermined amount on the road surface, it has a great effect on the running stability of the vehicle. It is desirable to suppress slip quickly. However, in the slip control device configured to estimate the vehicle speed as described above, there may be a large difference between the estimated vehicle speed and the actual vehicle speed. When all wheels slip more than a predetermined amount on the road surface based on an estimated vehicle speed that deviates significantly from the estimated vehicle speed, in addition to applying braking force to each wheel using the brake system, control is performed to reduce engine output. If this happens, the drive torque acting on the wheel that is slipping will be reduced more than necessary, which will impair the drive characteristics of the four-wheel drive vehicle, or the slip will not be suppressed sufficiently and the running stability of the vehicle will be affected. may have an impact.

Furthermore, when all wheels slip more than a predetermined amount on the road surface, even if slip control is performed in a predetermined control manner and the slip of each wheel is suppressed,
During the subsequent predetermined period, the same slip as before the slip control is performed again may occur and the running stability of the vehicle may be affected. It is desired that the control mode be such that each wheel does not slip more than a predetermined amount.

In view of these points, the present invention provides that, when a slip of more than a predetermined amount with respect to the road surface is detected for three or less of the wheels in a four-wheel drive vehicle, or for all wheels, the detected slip is detected in each case. In addition, when a slip of more than a predetermined value with respect to the road surface is detected for all wheels, the driving torque acting on the wheels is reduced more than necessary, or the slip is not sufficiently suppressed. A slip control device for a four-wheel drive vehicle that is capable of quickly and appropriately suppressing detected slips without causing any In a given period after being suppressed,
It is an object of the present invention to provide a slip control device for a four-wheel drive vehicle that can prevent slips exceeding a predetermined level from occurring in each wheel again.

(Means for Solving the Problems) In order to achieve the above-mentioned object, a slip control device for a four-wheel drive vehicle according to the present invention has a basic configuration as shown in FIG. The system includes a slip detection means for detecting the slip of each wheel on the road surface in a four-wheel drive vehicle, a brake means for applying braking force to each wheel individually, and a brake means for changing the output of an engine mounted on the four-wheel drive vehicle. It is configured to include an output adjustment means and a control means,
In the first form, when the slip detection means detects slip of three or less of the wheels with respect to the road surface by a predetermined amount or more, the control means causes the brake means to apply a braking force to the wheel on which the slip of the predetermined amount or more is detected. In addition, when the slip detection means detects that all of the wheels have a slip of more than a predetermined value on the road surface, the output adjustment means is caused to perform a braking operation to apply the slip of the wheels without causing the brake means to perform a braking operation. The engine is operated to reduce its output until it is substantially eliminated.

Further, in the second embodiment, when the slip detection means detects slip of three or less of the wheels with respect to the road surface by a predetermined amount or more, the control means causes the brake means to control the wheels on which the slip of the predetermined amount or more is detected. A braking operation that applies a braking force is performed, and when the slip detection means detects that all of the wheels are slipping more than a predetermined amount with respect to the road surface, the output adjustment means is caused to control the engine without causing the braking means to perform a braking operation. After reducing the output, an operation is performed to suppress the slip ratio of the wheels relative to the road surface to a predetermined value or less for a predetermined period.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 conceptually shows an example of a slip control device for a four-wheel drive vehicle according to the present invention, together with a vehicle to which it is applied.

In FIG. 2, the vehicle 5 is a four-wheel drive vehicle, and an engine 12 is mounted on the front part of the vehicle body IO. The engine 12 has, for example, four cylinders 11, and each of the cylinders 11 has a throttle actuator 13.
A mixture formed of fuel supplied from a fuel supply system and intake air is supplied through an intake passage 16 provided with a throttle valve 14 that is driven to open and close by a fuel supply system. 1 for each cylinder
The air-fuel mixture supplied into the exhaust passage 17 is combusted by the operation of the ignition system and is discharged into the exhaust passage 17.

The engine 12 is rotated by such combustion of the air-fuel mixture, and the generated torque is transmitted to the transmission 22° center differential center mechanism 23. Flohera shaft 2 for front wheel
4, the differential mechanism 25, the propeller shaft 26 for the rear wheels, and the differential mechanism 27.
, are transmitted to the right front wheel 20R2, the left rear wheel 21L, and the right rear wheel 21H, respectively.

A brake device 30 is provided in association with the front left wheel 20L, the front right wheel 20R1, the rear left wheel 21L, and the rear right wheel 21H.

The brake device 30 includes a disc brake 35 that includes a disc 32 attached to each of a left front wheel 20L, a right front wheel 20R, a left rear wheel 21L, and a right rear wheel 21R, and a caliper 34 provided with a brake pad that presses the disc 32.
It has A to 35D. Disc brake 35A~3
The caliper 34 in each of the wheels 5D is equipped with a wheel cylinder 36, and each wheel cylinder 36 is connected to a conduit 37a to 37d extending from the hydraulic pressure adjustment section 40, respectively. When brake fluid pressure is supplied to the wheel cylinder 36 from the fluid pressure adjustment unit 40 via conduits 37a to 37d, each caliper 34 applies a pressing force to the disc 32 according to the supplied brake fluid pressure. By pressing, the left front wheel 20L, right front wheel 20R2, left rear wheel 21L, and right rear wheel 21R are braked.

The hydraulic pressure adjustment unit 40 is supplied with hydraulic pressure corresponding 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 also supplied through a pump 44 and a pressure regulating valve 45. The hydraulic pressure generated by the hydraulic pressure is supplied through conduit 46. During normal braking in which no slip control is performed, the hydraulic pressure adjustment unit 40 operates to form a brake hydraulic pressure according to the depression operation of the brake pedal 41 and supply it to the disc brakes 35A to 35D through the conduits 37a to 37d. During slip control, the built-in electromagnetic on-off valve 5
Disc brake 35A~ according to the operating status of 1~58
The brake fluid pressure for the disc brakes 35D is individually formed and the brake fluid pressures are selectively supplied to the disc brakes 35A to 35D, respectively.

The electromagnetic on-off valves 51 to 58 include electromagnetic on-off valves 51 and 52, electromagnetic on-off valves 53 and 54. The disc brakes 35A to 35A are combined with the electromagnetic on-off valves 55 and 56 and the electromagnetic on-off valves 57 and 58, and each set is provided with a left front wheel 20L, a right front wheel 20R, a left rear wheel 21L, and a right rear wheel 21R. 35
It is said to be involved in adjusting the brake fluid pressure with respect to D. One of the electromagnetic on-off valves 51, 53, 55 and 57 of each set is opened, and the other electromagnetic 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; 57 is closed and the other electromagnetic on-off valves 52, 54, 56 and 58 are opened, the brake fluid pressure supplied to the disc brakes 35A to 35D is reduced, and all of the sets are When the disc brakes 35A to 35D are in the closed state, the brake fluid pressure supplied to the disc brakes 35A to 35D is maintained at the current state.

In addition to the above configuration, a control unit 100 is provided for controlling the opening and closing of the electromagnetic on-off valves 51 to 58 and controlling the operation of the throttle actuator 13. The control unit) 100 includes speed sensors 61 to 64 provided in connection with the left front wheel 20L, right front wheel 20R3, left rear wheel 21L, and right rear wheel 21R, respectively. Wheel 21L and right rear wheel 21
Detection signals S and -S4 corresponding to the circumferential speeds of R, detection signals St corresponding to the throttle opening obtained from the throttle opening sensor 65 provided in relation to the throttle valve 14, and the accelerator pedal 66. The accelerator pedal 66 obtained from the accelerator opening sensor 67 provided in connection with the
A detection signal Sa corresponding to the amount of depression of the steering wheel 68 and a detection signal Sd corresponding to the steering angles of the front left wheel 2OL and the front right wheel 20R obtained from a steering angle sensor 69 provided in relation to the steering wheel 68 are supplied. .

The control unit 100 receives the detection signal S.

~ S4 is taken in at a predetermined period, and the taken detection signals S1 to S4 are detected on the left front wheel 20L and the right front wheel 20R9.
The estimated vehicle speed value and stratified speed value are calculated based on the circumferential speed values of the left rear wheel 21L and right rear wheel 21R, and the estimated vehicle speed value and the stratified speed value are calculated.
, the calculated speed values for each stratification are compared with a predetermined value Aa to determine whether a slip of a predetermined value or more has occurred in each of the front right wheel 20R2, the rear left wheel 21L, and the rear right wheel 21R.

Then, among the front left wheel 20L, the front right wheel 20R1, the rear left wheel 21L, and the rear right wheel 21H, those whose stratified speed values are determined to be equal to or higher than the value Aa are deemed to have experienced a slip of more than a predetermined value with respect to the road surface. Slip control is performed, and the left front wheel 2O
If it is determined that the respective stratified speed values of L, front right wheel 2OR, rear left wheel 21L, and rear right wheel 21R are less than the value Aa, normal throttle opening control is performed.

When the normal throttle opening control is performed by the control unit 100, the normal target throttle opening is set according to the amount of depression of the accelerator pedal 66, which is detected by the detection signal Sa, and the detection signal St is set by the detection signal St, which indicates the throttle valve The normal target throttle opening and the throttle valve 14 are adjusted so that the opening of the throttle valve 14 is brought closer to the normal target throttle opening.
A throttle valve drive signal Ct corresponding to the difference between the opening degree and the opening degree is generated and supplied to the throttle actuator 13. As a result, the throttle valve 14 is driven to open and close by the throttle actuator 13, and its opening degree is controlled to match the normal target throttle opening degree.

Note that the normal target throttle opening is determined by the accelerator pedal 66.
As the amount of depression increases, the pressure increases in a predetermined proportional relationship.

When the control unit 100 performs the slip control, the control unit 100 performs the slip control at a speed equal to or higher than a predetermined speed for the road surface, which is determined based on the stratified speed values for each of the front left wheel 2OL, the front right wheel 2OR, the rear left wheel 21L, and the rear right wheel 21H. Which of the four wheels is the wheel in which the slip has occurred (hereinafter referred to as the slip wheel) and the number thereof are detected, and if there are multiple slip wheels detected, the number of slip wheels is detected. The number of slip wheels that have a predetermined amount of slip or more occurring at approximately the same time is detected, the number of the detected slip wheels, the number of slip wheels, and the number of slips that have a predetermined amount or more of a plurality of slip wheels that have occurred approximately at the same time. Based on the number of objects, the estimated vehicle speed used in setting the target slip ratio is calculated and the slip control mode is set.

When setting the estimated vehicle speed by the control unit 100, the detection signals S1 to S4 taken in one cycle before are detected.
and the estimated vehicle speed value V calculated based on the circumferential speed of the right rear wheel 21R. -I (where n is a positive integer) is a predetermined value v
When the vehicle is running at a high speed of h or more, and the calculated estimated vehicle speed value ■7-1 is less than the value vh, and the detection signal Sd
When the left front wheel 2OL and the right front wheel 2OR steering angle are less than the predetermined value 68 during low-speed straight running, the left front wheel 20
L, right front wheel 20R9, a predetermined correction coefficient α for the lowest value of the peripheral speeds of the left rear wheel 21L and the right rear wheel 21R. (
1) to calculate the estimated vehicle speed value Vn at that time. In addition, when the estimated vehicle speed value V, 1-1 is less than the value vh and the steering angle of the left front wheel 2OL and the right front wheel 2OR is greater than or equal to the value 08, when the vehicle is turning at a low speed, depending on the detected slipping wheel and its number, Estimated vehicle speeds are set in different setting modes based on circumferential speeds of wheels that do not slip more than a predetermined amount on the road surface (hereinafter referred to as non-slip wheels).

When setting the estimated vehicle speed during low-speed turning, the left turning state of the vehicle 5 is detected based on the steering angles of the front left wheel 2OL and the front right wheel 20R, when zero or one slipping wheel is detected. When the front left wheel 2OL and the rear right wheel 21R are non-slip wheels,
The estimated vehicle speed value Vn is calculated by multiplying the average value of the circumferential speed of the left front wheel 2OL and the circumferential speed of the right rear wheel 21R by a predetermined correction coefficient α. When it is detected that at least one of the wheels 21H is a slipping wheel and a left turn of the vehicle 5 is detected, the circumferential speed of the right front wheel 20R and the circumferential speed of the left rear wheel 21L, which are non-slip wheels, are detected. The estimated vehicle speed value Vn is calculated by multiplying the average value of the values by the correction coefficient α1. On the other hand, when the right turning state of the vehicle 5 is detected with zero or one slip wheel being detected, if the right front wheel 20R and the left rear wheel 21L are each non-slip wheels, The estimated vehicle speed value Vn is calculated by multiplying the average value of the circumferential speed of the right front wheel 2OR and the circumferential speed of the left rear wheel 21L by a correction coefficient α.
When it is detected that at least one of the wheels L is a slipping wheel and a right turn of the vehicle 5 is detected, the circumferential speed of the left front wheel 20L and the circumferential speed of the right rear wheel 21R, which are non-slip wheels, is detected. The estimated vehicle speed value Vn is calculated by multiplying the average value of the values by the correction coefficient α1.

Furthermore, when two slip wheels are detected, the non-slip wheels are the left front wheel 2OL and the right front wheel 2O.
R1 or, in the case of the left rear wheel 21L and right rear wheel 21R, the average value of the circumferential speed of the left front wheel 2OL and the circumferential speed of the right front wheel 2OR, or the circumferential speed of the left rear wheel 21L and the right rear wheel 21H. A predetermined correction coefficient α is calculated based on the average value of the circumferential speed of
The estimated vehicle speed value Vn is calculated by multiplying by 2. In addition, when the non-slip wheels are the left front wheel 2OL and the left rear wheel 21L, or the right front wheel 2OR and the right rear wheel 21R, the trajectory closest to the trajectory of the center of gravity of the vehicle 5 among the non-slip wheels is taken. The estimated vehicle speed value Vn is calculated by multiplying the circumferential speed of the wheel by the correction coefficient α2. Specifically, when the non-slip wheels are the left front wheel 2OL and the left rear wheel 21L, when the vehicle 5 is turning right, the left front wheel 20L
When the vehicle 5 is turning left, the circumferential speed of the left rear wheel 21L is multiplied by the correction coefficient α2.
On the other hand, when the non-slip wheels are the right front wheel 20R and the right rear wheel, when the vehicle 5 is turning to the right, the circumferential speed of the right front wheel 20R is multiplied by the correction coefficient α2, and the vehicle 5 When the vehicle is turning left, the circumferential speed of the right rear wheel 21R is multiplied by a correction coefficient α2 to calculate the estimated vehicle speed value Vn in each case.

On the other hand, the non-slip wheels are the left front wheel 20L and the right rear wheel 21R.
1 or, in the case of the right front wheel 2OR and the left rear wheel 2IL, the average value of the circumferential speed of the left front wheel 20L and the circumferential speed of the right rear wheel 21R, or the circumferential speed of the right front wheel 2OR and the left rear wheel 21.
The average value with the peripheral speed of L is multiplied by the correction coefficient α2,
An estimated vehicle speed value Vn is calculated.

When three slip wheels are detected,
The estimated vehicle speed value Vn is calculated by multiplying the circumferential speed of the remaining non-slip wheel by the correction coefficient α3.

When it is detected that the front left wheel 20L, the front right wheel 20R, the rear left wheel 21L, and the rear right wheel 21R are all slip wheels, the estimated vehicle speed value Vn calculated immediately before the slip wheels are detected is Estimated vehicle speed value Vn at that time
It is said that

Note that the above-mentioned correction coefficient α1. It is desirable that α2 and α3 are set so that 1>α, and α2>α, taking into account that the vehicle 5 is placed in an unstable state as the number of slip wheels increases.

In this way, the estimated vehicle speed is set according to which of the four wheels the slipping wheel is and the number of slipping wheels. The speed is set to a value that does not deviate greatly from the actual vehicle speed by taking into consideration the actual running condition of the vehicle 5 under a relatively simple configuration.

With the estimated vehicle speed set as described above, the control unit 100 performs slip control on the slip wheels based on a combination of the number of slip wheels and two or more of the four wheels of the vehicle 5. The following is performed according to a predetermined control mode.

In the slip control by the control unit 100, depending on the number of slip wheels and the combination of 21 or more of the four wheels on the vehicle 5,
The brake device 30 includes a left front wheel 20L, a right front wheel 2 (IR,
Brake control that applies braking force to each of the left rear wheel 21L and right rear wheel 21R, and throttle control that reduces the engine output by reducing the opening degree of the throttle valve 14 are selectively performed. At the same time, the target slip rate TGBR in brake control is set to three predetermined values TGI-TG3 (however, 0<TG
I<TG2<TG3), and the target slip rate TGTR in throttle control is selected and set to one of the values TGl-TC;3.

When brake control and throttle control are performed, the estimated vehicle speed value ■n calculated as described above is used, and Actual slip rate SFL, S
FR, SRL and SRR are each expressed by the formula; 5FL= (
VFLn-Vn)/VFLn, 5FR= (VFRn-
Vn)/VFRn, 5RL-(VRLn-Vn)/
VRLn and 5RR= (VRRn-Vn)/VR
Calculated by Rn (VFLn, VFRn, VRLn
and VRRn (where n is a positive integer) are the front left wheel 20L, the front right wheel 20R, the rear left wheel 21L, and the rear right wheel 21R, respectively.
value of circumferential velocity).

When brake control is performed, the drive signal Ca - Ch
is selectively formed and supplied to the electromagnetic on-off valves 51-5. As a result, the left front wheel is 20L, the right front wheel is 20R.
1. The brake fluid pressure for the disc brakes 35A to 35D attached to the left rear wheel 21L and right rear wheel 21R is adjusted, and the slip rate of the slipping wheel is controlled to match the value TGI.

In addition, when throttle control is performed, the actual slip ratios SFL, SFR, SRL and SRR and the value TGI,
Based on the comparison with the target slip ratio TGTR, which is set by selecting either TG2 or TG3, the control unit 100 forms a throttle valve drive signal Ct, which is supplied to the throttle actuator 13.

As a result, the opening degree of the throttle valve 14 is adjusted, and the slip rate of the slipping wheel is adjusted to the value TGI, TG2 or T.
It is controlled to match G3. However, during such throttle control, if the opening degree of the throttle valve 14 is larger than the normal target throttle opening degree set according to the amount of depression of the accelerator pedal 66, such throttle control is stopped and the normal throttle Control begins.

As mentioned above, brake control and throttle control are selectively performed depending on the number of slipping wheels and the combination of slipping wheels, but when it is detected that there is only one slipping wheel, only brake control is performed. will be held. In addition, when it is detected that there are two slip wheels, one of the predetermined control modes is selected according to each of the six combinations of two of the four wheels. It will be done according to the following. That is, when the left rear wheel 21L and the right rear wheel 21R are slip wheels, only brake control is performed, and when the left front wheel 20L and right front wheel 20R are slip wheels, the left rear wheel 21L and the right rear wheel are ring 21
Since the influence on the running stability of the vehicle 5 is likely to be greater than when R is a slipping wheel, in addition to brake control, throttle control is performed in which the target slip rate TGTR is set to the value TG3, and the slipping wheel is Left front wheel 20L and left rear wheel 21L1 or right front wheel 2OR and right rear wheel 2
1R, there is a risk that yaw motion will occur in the vehicle 5, so in addition to brake control, the target slip rate TGT is
Throttle control is performed with R set to the value TG2, and only brake control is performed when the slip wheels are the front left wheel 20L and the rear right wheel 21R1 or the front right wheel 20R and the rear left wheel 21L.

In this way, when it is detected that there are two slip wheels, the slip control mode is set according to the combination of those slip wheels, so that the influence on the running stability of the vehicle 5 is relatively small. When it is small, only brake control is performed, so the engine output is not reduced and the wheel drive torque is not reduced more than necessary. In addition, when the impact on the running stability of the vehicle 5 is likely to be large, throttle control is performed in addition to brake control, so that yaw motion that would affect the vehicle 5 is suppressed. Situations that may occur are effectively avoided.

On the other hand, there are three slip wheels detected, and
If these slips exceeding a predetermined value occur almost simultaneously, the running condition of the vehicle 5 is extremely unstable, so only throttle control is performed with the target slip rate TGTR set to the value TG2. . Furthermore, if the three slip wheels do not experience slips of a predetermined or higher level at the same time, in addition to the brake control, throttle control is performed in which the target slip rate TGTR is set to the value TG2.

Furthermore, when it is detected that there are four slipping wheels, the brake control is stopped, the target slip rate TGTR is set to zero, and throttle control is performed to fully close the throttle valve 14. Then, in order to judge whether or not each of the four wheels is in a substantially slip-free state with the throttle valve 14 in the fully closed state, the circumferential speed average value VAV is calculated using the formula; VAV= ( VFL
n+VF Rn +V RL n 10V RRn)
/ 4 is calculated, and the calculated circumferential velocity average value VAV
is used, and the total deviation value ε is calculated using the formula; t= (VFLn
−VAV) 2+ (VFRn−VAV)” + (V
RLn-VAV)" + (VRRn-VAV)", and the calculated total deviation value ε is a predetermined value Za.
It is determined whether or not the following is true. The total deviation value ε is the value Za
If it is determined that the four wheels are not in a slip-free state, the throttle valve 14
If the fully closed state is maintained and the total deviation value ε is determined to be less than or equal to the value Za, it is assumed that the four wheels are in a substantially slip-free state and slip control is restarted.

When slip control is restarted, the total deviation value ε
Brake control is not performed until a predetermined period Tx has elapsed from the time when T becomes equal to or less than the value Za, and the target slip rate T
Only throttle control with GTR set to value TGI is performed. However, when throttle control is being performed with the target slip ratio TGTR set to the value TGI, the throttle valve 14
When the opening degree is larger than the normal target throttle opening degree set according to the amount of depression of the accelerator pedal 66,
Such throttle control is stopped and normal throttle opening control is started.

In this way, when it is detected that all four wheels are slipping more than a predetermined amount on the road surface, the brake control is stopped until the four wheels are substantially free from slipping. By maintaining the throttle valve 14 in a fully closed state and quickly reducing the engine output, a situation that affects the running stability of the vehicle 5 is avoided, and the four wheels are quickly reduced. is brought into a state where there is virtually no slippage. Therefore, even if the four wheels slip more than a predetermined amount with respect to the road surface, a driving 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. Also, 4
After the four wheels are brought into a state where there is virtually no slip, until the period Tx has elapsed, there is a high possibility that the four wheels will again experience more than a predetermined amount of slip on the road surface. During this period, only the throttle control is performed to suppress the occurrence of more than a predetermined amount of slip, so that the vehicle 5 immediately after the four wheels are in a state where there is substantially no slip is driving stability is ensured.

The slip control as described above is mainly performed based on the operation of a microcomputer built into the control unit 100. For an example of a program executed by such a microcomputer, see the flowcharts in FIGS. 3 to 9. and explain.

In the main program shown in the flowchart of FIG. 3, after starting, initial settings are performed in process 101, and in process 102, the detection signal S+ =S
4. A process is performed to import St, Sa, and Sd to create necessary data, and in subsequent processes 103 to 107, a slip determination program, an estimated vehicle speed setting program, a control mode setting program, a throttle control program, and a brake are sequentially executed. The control program is executed and the process returns to process 102.

The slip determination program executed in process 103 in the flowchart of FIG.
1, the simultaneous slip count flag SFS is set to zero, and in process 112, the left front wheel 20L one cycle before
Set the circumferential speed value ■FLn-+ as the value vWO, set the circumferential speed value VFLn of the left front wheel 20L at that time as the circumferential speed value VWN, and set the slip wheel determination flag SFQ.
Set the left front wheel slip flag 5FFL and process 11.
3, a slip detection program as shown in FIG. 5 is executed.

In the slip detection program shown in FIG. 5, after starting, in process 131, the circumferential speed value ■WO is deleted from the circumferential speed value VWN to calculate the stratified speed Δ■W of the left front wheel 2OL. In the subsequent decision 132, it is determined whether the stratified speed Δ■W is greater than or equal to the value Aa, and if it is determined that the stratified velocity ΔvW is greater than or equal to the value Aa, the left front wheel 20L is caused to slip more than a predetermined value. has occurred, and in process 133, the slip wheel determination flag SFQ is set to 1, 1 is added to the simultaneous slip count flag SFS, a new simultaneous slip count flag SFS is set, and this program is terminated. , if it is determined in decision 132 that the stratified velocity ΔVW is less than the value Aa, this program is terminated without going through process 133. After completing the program shown in FIG. 5, in process 114 in the flowchart shown in FIG.
FFL is replaced with the slip wheel determination flag SFQ and the process proceeds to process 115.

In process 115, the right front wheel 2OR (
7) Set the circumferential velocity value VFR,-, to the value VWO, and
The value VFRn of the circumferential speed of the right front wheel 20R at that time is the value VW
At the same time, the slip wheel determination flag SFQ is set to the right front wheel slip flag 5FFR, and in process 116, a slip detection program as shown in FIG. The wheel determination flag is replaced with SFQ and the process proceeds to process 118. In process 118, the peripheral speed value VRL of the left rear wheel 21L one cycle before,
, is set as the value ■WO, and the circumferential velocity value VRLn of the left rear wheel 21L at that time is set as the value VWN, and the slip wheel determination flag SFQ is set as the left rear wheel slip flag 5FR.
In process 119, a slip detection program as shown in FIG.
Proceed to step 2. In process 122, the value VRRn of the peripheral speed of the right rear wheel 21H one cycle before.

is set as the value ■WO, and the value VRRn of the circumferential speed of the right rear wheel 21R at that time is set as the value VWN, and the slip wheel determination flag SFQ is set as the right rear wheel slip flag 5FRR.
Then, in process 123, after executing a slip detection program as shown in FIG.
Proceed to.

In process 125, the left front wheel slip flag 5F
FL, right front wheel slip flag 5FFR.

A slip wheel count flag SF is set by adding the left rear wheel slip flag 5FRL and the right rear wheel slip flag 5FRR, and in the subsequent decision 126, it is determined whether or not the accelerator pedal 66 is in the released state, and the accelerator pedal is If it is determined that the accelerator pedal 66 is in the released state, the program is terminated after the slip wheel count flag SF is set to zero in process 127, and in decision 126, the accelerator pedal 66 is set in the released state. If it is determined that the program has not been executed, the program is terminated without going through process 127.

On the other hand, process 104 in the flowchart of FIG.
As shown in the flowchart of FIG. 6, after the program for setting the estimated vehicle speed is started, in process 140, the program for setting the estimated vehicle speed is set to the value V of the estimated vehicle speed set one cycle earlier.
It is determined whether or not n-1 is greater than or equal to the value vh, and if it is determined that the estimated vehicle speed value V, , is greater than or equal to the value ■h, in process 141, the estimated vehicle speed value Vn is sent to the detection signal. S
.

~S4 is the value of the circumferential speed of the front left wheel 2OL, the front right wheel 20R1, the rear left wheel 21L, and the rear right wheel 21R, respectively.
A correction coefficient α is applied to the smallest of FLn, VFRn, VRLn, and VRRn. The program is then terminated, and at decision 140,
If it is determined that the estimated vehicle speed value V7-1 is less than the value vh, in decision 142, the detection signal Sd
When a storm occurs, it is determined whether the steering angle θ of the left front wheel 2OL and the right front wheel 20R is greater than or equal to the value 08, and if it is determined that the steering angle θ is less than the value 08, the process 141 is performed in the same manner as described above. Execute the program to end this program, and set the steering angle θ to the value 08.
If it is determined that the above is the case, Decision 143
Proceed to.

In isotion 143, it is determined whether the slip wheel count flag SF is zero or 1, and if it is determined that the slip wheel count flag SF is zero or 1, in decision 144, the steering angle θ is Based on this, it is determined whether the vehicle 5 is in a right turning state, and the vehicle 5 is
If it is determined that the front right wheel slip flag 5FFR is turning to the right, it is determined in decision 145 whether or not the front right wheel slip flag 5FFR is zero, and the front right wheel slip flag 5FFR is set to zero.
is determined to be zero, decision 146
In step 147, it is determined whether or not the left rear wheel slip flag 5FRL is zero, and if it is determined that the left rear wheel slip flag 5FRL is zero, in process 147, the estimated vehicle speed value Vn is calculated using the formula; = ((VFRn+VRLn
)/2) Xα1 is calculated and this program is terminated, and if it is determined in decisions 145 and 146 that the front right wheel slip flag 5FFR and the rear left wheel slip flag 5FRL are not zero, process 1 is executed.
In step 48, the estimated vehicle speed value Vn is calculated using the formula: % formula %), and this program ends.

On the other hand, if it is determined in decision 144 that the vehicle 5 is not turning to the right, then in decision 151 it is determined whether or not the front left wheel slip flag 5FFL is zero. If it is determined that the right rear wheel slip flag 5FRR is zero, it is determined in decision 152 whether the right rear wheel slip flag 5FRR is zero, and if it is determined that the right rear wheel slip flag 5FRR is zero, the process 153 The estimated vehicle speed value Vn
Formula; Vn= ((VFLn+VRRn)/2)Xα
If it is determined in decisions 151 and 152 that the left front wheel slip flag 5FFL and the right rear wheel slip flag 5FRR are not zero, in process 154,
The estimated vehicle speed value Vn is 2; Vn= ((VFRn + VRL
n)/2) Xα1 and terminate this program.

If it is determined in decision 143 that the slip wheel count flag SF is not zero or 1, then in decision 155 it is determined whether or not the slip wheel count flag SF is 2, and the slip wheel count flag SF is 2, in decision 156, it is determined whether or not the right front wheel slip flag 5FFR is zero, and the right front wheel slip flag 5FFR is set to zero.
is not zero, decision 157
, it is determined whether the right rear wheel slip flag 5FRR is zero, and if it is determined that the right rear wheel slip flag 5FRR is not zero, then in decision 15B, the vehicle 5 is in a right-turning state. Determine whether or not.

If it is determined that the vehicle 5 is turning right, in process 159, the estimated vehicle speed value Vn is calculated using the formula + V n = V F L n Xα2, and this program is terminated in the winter. . If it is determined in decision 15B that the vehicle 5 is not in a right-turning state, in process 160, the estimated vehicle speed later value Vn is calculated using the formula HVn=VRLnXα2, and this program is ended.

On the other hand, if it is determined in decision 157 that the right rear wheel slip flag 5FRR is zero, then in decision 161 the left front wheel slip flag 5FFL is determined to be zero.
is zero, and set the left front wheel slip flag 5F.
If FL is determined to be zero, process 162
, the estimated vehicle speed value Vn is expressed as; Vn= ((VF
Ln+VRRn)/2)
Vn=(CVRRn+VRLn)/2)Xα2 is calculated, and this program ends.

Further, if it is determined in decision 156 that the front right wheel slip flag 5FFR is zero, in decision 163, the front left wheel slip flag 5FFR is set to zero.
is zero, and set the left front wheel slip flag 5F.
If FL is determined to be zero, process 164
, the estimated vehicle speed value Vn is expressed as; Vn= ((VFR
If it is determined in decision 163 that the left front wheel slip flag 5FFL is not zero, then in decision 165 the left rear wheel slip flag 5FRL is Determine whether or not. If it is determined that the left rear wheel slip flag 5FRL is zero, then in process 166, the estimated vehicle speed value Vn is calculated using the formula;
Vn=((VFRn+VRLn)/2)×crt, and this program ends. On the other hand, at decision 165, left rear wheel slip flag 5FRL
is not zero, decision 167
In step 168, it is determined whether the vehicle 5 is in a right-turning state, and if it is determined that the vehicle 5 is not in a right-turning state, in process 168, the estimated vehicle speed value Vn is calculated by the formula;
Vn = VRRn
9, the estimated vehicle speed value Vn is calculated using the formula: ■n=■FRn×α
2 and terminate this program.

Furthermore, if it is determined in decision 155 that the slip wheel count flag SF is not 2, then in decision 171 it is determined whether or not the slip wheel count flag SF is 3, and the slip wheel count flag SF is
is determined to be 3, decision 172
In step 173, it is determined whether or not the right front wheel slip flag 5FFR is zero, and if it is determined that the right front wheel slip flag 5FFR is zero, in process 173, the estimated vehicle speed value Vn is calculated using the formula: Vn=VFRnXα, Calculated by If it is determined in decision 172 that the front right wheel slip flag 5FFR is not zero, then in decision 174 the front left wheel slip flag 5FFR is
is zero or not, and set the left front wheel slip flag 5F.
If FL is determined to be zero, process 175
, the estimated vehicle speed value Vn is calculated using the formula; V n =V F
This program is completed by calculating L n Xα3. If it is determined in decision 174 that the left front wheel slip flag 5FFL is not zero, then in decision 176 the right rear wheel slip flag 5FFL is determined to be non-zero.
is zero, and set the right rear wheel slip flag 5F.
If it is determined that RR is zero, process 177
In, the estimated vehicle speed value Vn is expressed as; Vn=VRRnX
α, and this program is terminated, and in decision 176, the right rear wheel slip flag 5F is calculated.
If it is determined that RR is not zero, process 178
, the estimated vehicle speed value Vn is calculated using the formula: Vn=VRLn×
Calculate using αgo and end this program.

On the other hand, if it is determined in decision 171 that the slip wheel count flag SF is not three, this program is terminated.

Then, process 10 in the flowchart of FIG.
As shown in FIG. 7, the control mode setting program executed in step 5 determines in decision 179 after the start whether or not the four-wheel slip control flag CF4, which will be described later, is zero, which indicates a steady state. If it is determined that the four-wheel slip control flag CF4 is zero, in decision 180, the slip wheel count flag SF is
is l, and sets the slip wheel count flag S
If it is determined that F is 1, in process 181, the brake control execution flag EBF is set to 1, and the throttle control execution flag ETF is set to zero, and in process 182, the target slip rate for throttle control is set. Set TGTR to value TG2 and process 183
In this step, the target slip ratio TGBR for brake control is set to the value TG1, and this program is ended.

Further, if it is determined in decision 180 that the slip wheel count flag SF is not 1, then in decision 184 the slip wheel count flag SF is determined to be 2.
If it is determined that the slip wheel count flag SF is 2, it is determined in decision 185 whether or not the right front wheel slip flag 5FFR is zero. And front right wheel slip flag 5FFR
is determined to be zero, decision 186
, it is determined whether or not the left front wheel slip flag 5FFL is zero, and if it is determined that the left front wheel slip flag 5FFL is zero, the left rear wheel 21L and the right rear wheel 21
Since R is slipping more than a predetermined value on the road surface, the brake control execution flag EB is set in process 187.
F is set to 1, and the throttle control execution flag ETF is set to 0, and the process proceeds to process 182.
The subsequent processes are executed sequentially in the same manner as described above, and this program ends.

On the other hand, if it is determined in decision 186 that the left front wheel slip flag 5FFL is not zero, then in decision 188 it is determined whether or not the left rear wheel slip flag 5FRL is zero, and the left rear wheel slip flag 5FFL is determined to be zero.
If it is determined that L is not zero, the left front 1iii2
Since the OL and left rear wheel 21L are slipping more than a predetermined amount on the road surface, in process 189, the target slip rate TGTR is set to the value TG2, and in process 194
Proceed to. If it is determined in decision 185 that the right front wheel slip flag 5FFR is not zero, then in decision 190 it is determined whether or not the right rear wheel slip flag 5FRR is zero, and the right rear wheel slip flag 5FRR is determined to be zero. If it is determined that the slip flag is zero, in decision 191, the left front wheel slip flag 5FFL is set.
is zero, and set the left front wheel slip flag 5F.
If it is determined that FL is not zero, then the front left wheel 2OL and the front right wheel 2OR are causing more than a predetermined amount of slip on the road surface, so in process 192, the target slip rate TGTR is set to the value TG3, and the process goes to process 194. move on. Furthermore, if it is determined in decision 190 that the right rear wheel slip flag 5FRR is not zero, then the right front wheel 2OR and the right rear wheel 21R are slipping more than a predetermined amount on the road surface, so in process 193, the target The slip ratio TGTR is set to the value TG2 and the process proceeds to process 194. In process 194, the brake control execution flag EBF and the throttle control execution flag E
TF are both set to 1, and in the subsequent process 183,
The target slip ratio TGBR is set to the value TGI and this program is ended.

Furthermore, if it is determined in decision 188 that the left rear wheel slip flag 5FRL is zero, this means that the left front wheel 20L and the right rear wheel 21R are slipping more than a predetermined amount, and in decision 191, the left front wheel slip flag 5FRL is determined to be zero. If it is determined that 5FFL is zero, the front right wheel 2OR and the rear left wheel 21L are slipping more than a predetermined amount. Execute in the same manner as above to terminate this program.

On the other hand, if it is determined in decision 184 that the slip wheel count flag SF is not 2, then in decision 196 the slip wheel count flag SF is determined to be 3.
If it is determined that the slip wheel count flag SF is 3, it is determined in decision 197 whether or not the three-wheel simultaneous slip occurrence flag CF3 is zero, and the three-wheel If it is determined that the simultaneous slip occurrence flag CF3 is zero, it is determined in decision 198 whether or not the simultaneous slip count flag SFS is 3, and if it is determined that the simultaneous slip count flag SFS is not 3. In step 199, the target slip ratio TGTR is set to the value TG2, and both the brake control execution flag EBF and the throttle control execution flag ETF are set to 1, and in the process 183, the target slip ratio TGBR is set to the value TGI. Exit this program. Further, if it is determined in decision 197 that the three-wheel simultaneous slip occurrence flag CF3 is not zero, and if it is determined that the simultaneous slip count flag SFS is 3 in decision 198, the target slip is determined in process 200. rate TGTR
is set to the value TG2, the brake control execution flag EBF and the throttle control execution flag ETF are both set to 1, and the three-wheel simultaneous slip occurrence flag CF3 is set to 1, and process 183 is executed in the same manner as described above. Exit the program.

If it is determined in decision 196 that the slip wheel count flag SF is not 3, then decision 2
At step 01, it is determined whether or not the slip wheel count flag SF is 4. If it is determined that the slip wheel count flag SF is 4, the process proceeds to decision 202.

Also, if it is determined in decision 179 that the four-wheel slip control flag CF4 is not zero, the process advances to decision 202, and in decision 202, the four-wheel slip control flag CF4 is
It is determined whether the wheel slip control flag CF4 is 2 indicating a slip convergence state. Then, if it is determined that the four-wheel slip control flag CF4 is not 2, in decision 203, the four-wheel slip control flag C
Determine whether F4 is zero, which indicates a steady state, and
If it is determined that the wheel slip control flag CF4 is zero, in process 204, the target slip rate T is
GTR is set to zero, the brake control execution flag EBF is set to Ambient, the throttle control execution flag ETF is set to 1, and the 4-wheel slip control flag CF4 is set to 1 for the slip convergence process, and the process proceeds to process 205. On the other hand, if it is determined in decision 203 that the four-wheel slip control flag CF4 is not zero, the process directly proceeds to process 205.

In process 205, the circumferential velocity values VFLn, VF
Calculate the circumferential velocity average value VAV by adding Rn, VRLn and VRRn and dividing by 4, followed by process 206
The total deviation value ε is calculated using the formula: % formula %VAV)'', and in decision 207 it is determined whether the total deviation value ε is less than or equal to a predetermined value Za. If it is determined, proceed directly to process 183, execute process 183 in the same manner as described above, and terminate this program.If it is determined in decision 207 that the total deviation value ε is less than or equal to the value Za, , in process 208, the target slip ratio TGTR is set to the value TGI, the four-wheel slip control flag CF4 is set to 2, and the built-in timer is started to begin measuring the elapsed time T. Then, in the subsequent decision 210, the elapsed time is It is determined whether T is greater than or equal to a predetermined time length Tx, and the elapsed time T
If it is determined that the elapsed time T is less than the time length Tx, execute the process 183 in the same manner as described above and terminate this program, and if it is determined that the elapsed time T is greater than or equal to the time length Tx, in the process 213, Brake control execution flag EBF
, throttle control execution flag ETF, 3-wheel simultaneous slip occurrence flag CF3.4-wheel slip control flag CF4
．． The slip wheel count flag SF is set to zero, the built-in timer is reset, and the process 183 is executed in the same manner as described above, and then this program is terminated. Further, even if it is determined in process 201 that the slip wheel count flag SF is not 4, process 213 and process 183 are executed in the same manner as described above, and the process returns to the original state.

As shown in FIG. 8, the throttle control program of process 106 in the flowchart of FIG. If it is determined that E is zero, in process 221 the normal throttle opening control program is executed and this program is terminated, and in decision 220 the throttle control execution flag E is
If it is determined that TF is not zero, Decision 2
In step 22, it is determined whether the target slip ratio TGTR is zero, and if it is determined that the target slip ratio TGTR is zero, in step 224, the throttle valve is driven to fully close the throttle valve 14. The signal Ct is sent to the throttle actuator 13 and this program is terminated.

Further, in decision 222, the target slip rate T
If it is determined that GTR is not zero, it is determined in decision 225 whether or not the opening Th of the throttle valve 14 is equal to or lower than the normal target throttle opening TK set according to the amount of depression of the accelerator pedal 66. If it is determined that the opening Th of the throttle valve 14 is larger than the normal target throttle opening TK, a normal throttle opening control program is executed in process 221, and this program is terminated. Further, if it is determined in decision 225 that the opening Th of the throttle valve 14 is equal to or lower than the normal target throttle opening TK, in process 226, the estimated vehicle speed value Vn is used to
0L, the right front wheel 20R9, the average slip rate SAV of the left rear wheel 21L, and the right rear wheel 21R, which have a slip of more than a predetermined value on the road surface, is calculated, and in process 227, the average slip rate SA is calculated from the target slip rate TGTR.
The difference ΔS is calculated by subtracting V. Then, in the subsequent process 228, in order to make the average slip ratio SAV match the target slip ratio TGTR, a throttle valve drive signal Ct is formed according to the difference ΔS, and is sent to the throttle actuator 13, and this program ends.

Furthermore, process 10 in the flowchart of FIG.
As shown in FIG. 9, after starting, the brake control program No. 7 determines whether or not the brake control execution flag EBF is zero at decision 230, and determines that the brake control execution flag EBF is zero. If so, in process 231, the drive signal Ca %
Stop sending out Ch and apply disc brakes 35A to 35D.
After setting the brake control execution flag EBF to the released state, this program is terminated, and in decision 230, the brake control execution flag EBF is set.
is not zero, decision 232
At this point, it is determined whether the left front wheel slip flag 5FFL is zero. And front left wheel slip flag 5FFL
If it is determined that is not zero, in process 233, the estimated vehicle speed value Vn is used to calculate the actual slip rate SFL of the left front wheel 20L using the formula; 5FL= ('VFLn-Vn
)/VFLn, and in the subsequent process 234, the actual slip rate SFL and the target slip rate TGBR
In order to match the drive signals Ca and c based on the comparison between the actual slip ratio SFL and the target slip ratio TGBR.
b is selectively sent to the electromagnetic on-off valves 51 and 52, and the process proceeds to decision 235. Further, if it is determined in decision 232 that the left front wheel slip flag 5FFL is zero, the process also proceeds to decision 235. In decision 235, right front wheel slip flag 5FFR
is zero, and set the right front wheel slip flag 5F.
If it is determined that FR is not zero, process 236
, the actual slip rate SFR of the right front wheel 2OR is calculated using the estimated vehicle speed value Vn using the formula; 5FR= (VFRn-V
n)/VFRn, and in the subsequent process 237, the actual slip ratio SFR and the target slip ratio TGB
In order to match R, drive signals Cc and Cd are selectively sent to the electromagnetic on-off valves 53 and 54 based on a comparison between the actual slip ratio SFR and the target slip ratio TGBR, and the process proceeds to decision 238. Further, if it is determined in decision 235 that the right front wheel slip flag 5FFR is zero, the process also proceeds to decision 238. In decision 238, left rear wheel slip flag 5FRL
is zero, and set the left rear wheel slip flag 5F.
If it is determined that RL is not zero, process 239
, the actual slip rate SRL of the left rear wheel 21L is calculated using the estimated vehicle speed value Vn using the formula; 5RL= (VRLn-
Vn)/VRLn, and in the subsequent process 240, the actual slip ratio SRL and the target slip ratio TG
In order to match the BR, drive signals Ce and Cf are selectively sent to the electromagnetic on-off valves 55 and 56 based on a comparison between the actual slip ratio SRL and the target slip ratio TGBR.
Proceed to decision 241. Also, Decision 238
In the case where it is determined that the left rear wheel slip flag 5FRL is zero, the process also proceeds to decision 241. In decision 241, right rear wheel slip flag 5F
It is determined whether or not RR is zero, and if it is determined that the right rear wheel slip flag 5FRR is not zero, process 2 is performed.
42, the right rear wheel 21R is set using the estimated vehicle speed value Vn.
The actual slip rate SRR of 5RR=(VRR
n-Vn)/VRRn, followed by process 24
3, in order to match the actual slip rate SRR and the target slip rate TGBR, the actual slip rate SRR
Based on the comparison with the target slip ratio TCI;BR, the drive signals Cg and ch are selectively sent to the electromagnetic on-off valves 57 and 58, and this program ends. Further, if it is determined in decision 241 that the right rear wheel slip flag 5FRR is zero, process 231 is executed in the same manner as described above and this program is terminated.

In addition, in the above example, when slip of more than a predetermined value is detected for four wheels, the output of Nishijin is reduced until the slip of the four wheels is substantially eliminated, and then in the predetermined period. , throttle control is performed to set the slip ratio of each wheel to a predetermined value, but it is not necessary to do so.
During the above-mentioned predetermined period, throttle control may be performed so that the slip rate of each wheel is suppressed to a predetermined value or less, and even in such a case, the same procedure as in the above-mentioned example is performed. Effects can be obtained.

Furthermore, in the above example, when slip of the four wheels with respect to the road surface is detected to be more than a predetermined value, the throttle valve is fully closed and the engine output is reduced until the slip of the four wheels is substantially eliminated. After being lowered,
Although only throttle control is performed without brake control for a predetermined period, it is not necessary to do so, and the four wheels are kept in a state where there is substantially no slip on the road surface. After that, the brake control or the brake control and throttle control may be restarted.
After each wheel is brought into a state where there is substantially no slip on the road surface, the estimated vehicle speed is equal to or approximately equal to the actual vehicle speed, so proper slip control can be resumed. become.

Furthermore, in the above example, the engine output during slip control is adjusted by changing the throttle opening, but it is not necessary to do so, and instead of adjusting the throttle opening. Air fuel ratio 3 ignition timing, exhaust recirculation amount.

The adjustment may be made by changing the intake/exhaust valve opening/closing timing, boost pressure, fuel injection timing, etc.

Furthermore, although the above example is applied to a full-time four-wheel drive vehicle that is always in four-wheel drive mode, the present invention is not limited thereto; It can also be applied to part-time four-wheel drive vehicles that can be selectively changed.

(Effects of the Invention) As is clear from the above description, according to the first embodiment of the slip control device for a four-wheel drive vehicle according to the present invention, when a slip of more than a predetermined value occurs in all wheels, the running of the vehicle is stabilized. It is possible to quickly bring each wheel to a state where no slip occurs, without affecting the vehicle speed. A driving state in which the vehicle speed is equal to or substantially equal to the vehicle speed can be obtained in a very short time, and thereafter, control can be performed to appropriately suppress slip based on the estimated vehicle speed.

Further, according to the second embodiment of the slip control device for a four-wheel drive vehicle according to the present invention, when slips of a predetermined amount or more occur in all wheels, after the slips of each wheel are reduced, a predetermined period of time is elapsed. , it is possible to obtain a state in which re-occurrence of slip of each wheel on the road surface by a predetermined amount or more is prevented, thereby making it possible to maintain running stability of the vehicle.

[Brief explanation of the drawing]

FIG. 1 is a basic configuration diagram showing a slip control device for a four-wheel drive vehicle according to the present invention in accordance with the claims, and FIG. 2 is an example of a slip control device for a four-wheel drive vehicle according to the present invention.
The conceptual diagrams shown together with the vehicle to which it is applied, and Figs. 3 to 9, show an example of a program executed by a microcomputer when a microcomputer is used in the control unit of the example shown in Fig. 2. FIG. In the figure, 5 is the vehicle, 12 is the engine, 13 is the throttle actuator, 14 is the throttle valve, 2OL is the left front wheel,
2OR is the right front wheel, 21L is the left rear wheel, 21R is the right rear wheel, 3
0 is a brake device, 35A to 35D are disc brakes, 40 is a hydraulic pressure adjustment section, 61 to 64 are speed sensors, 65 is a throttle opening sensor, 67 is an accelerator opening sensor, 1
00 is a control unit. Patent applicant Mazda Motor Corporation

Claims (1)

[Scope of Claims] 1. Slip detection means for detecting slip of each wheel on a road surface in a four-wheel drive vehicle; Brake means for individually applying braking force to each of the wheels; installed in the four-wheel drive vehicle. output adjusting means for changing the output of the engine, and when the slip detecting means detects a slip of more than a predetermined value with respect to the road surface for three or less of the wheels, the brake means detects a slip of more than the predetermined value; causing the detected wheel to perform a braking operation to apply a braking force, and when the slip detection means detects that all of the wheels slip more than the predetermined amount on the road surface, the braking means performs the braking operation. A slip control device for a four-wheel drive vehicle, comprising: control means for causing the output adjustment means to perform an operation of reducing the output of the engine until the slip of the wheels is substantially eliminated; . 2. Slip detection means for detecting the slip of each wheel on a road surface in a four-wheel drive vehicle; a brake means for applying braking force to each of the wheels individually; and when the slip detecting means detects a slip of more than a predetermined amount on the road surface with respect to three or less of the wheels, the braking means is configured to control the wheel on which the slip of more than the predetermined amount is detected. A braking operation that applies power is performed, and when the slip detecting means detects that all of the wheels have slipped more than the predetermined amount with respect to the road surface, the output is increased without causing the braking means to perform the braking operation. A four-wheel drive comprising: control means for causing the adjustment means to perform an operation to suppress the slip ratio of the wheels relative to the road surface to a predetermined value or less for a predetermined period after reducing the output of the engine; Car slip control device.