JP2697145B2 - Vehicle acceleration slip control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acceleration slip control device for a vehicle that suppresses an acceleration slip generated on a drive wheel during vehicle acceleration.

2. Description of the Related Art Conventionally, as one of vehicle acceleration slip control devices, Japanese Patent Application Laid-Open No. 61-85248 discloses a method of controlling opening and closing of a throttle valve (throttle control) when an acceleration slip occurs in a driving wheel. There has been proposed a device that controls the rotation speed of a drive wheel by simultaneously performing drive control (brake control) of a brake device provided on the wheel.

This type of device has a problem that occurs when the acceleration slip control is performed only by the throttle control or the brake control, that is, in the throttle control, after the control is executed, the internal combustion engine is operated with the air amount corresponding to the opening degree. It takes time, and it takes time to suppress the acceleration slip generated on the drive wheels. In the brake control, the rotation of the drive wheels can be directly controlled,
Although the responsiveness is good, the problem that the rotation of the drive wheels must be suppressed against the drive torque from the internal combustion engine, the load applied to the braking device increases, and the life of the braking device is shortened, Since the controls complement each other to execute the acceleration slip control, it is possible to satisfactorily suppress the acceleration slip generated in the drive wheels with good responsiveness.

[Problems to be Solved by the Invention] However, in the above-described conventional device, the brake control and the throttle control are performed independently of each other.
These two controls interfere with each other, and there is a problem that it takes time for the drive wheel speed during vehicle acceleration to converge to the target drive wheel speed. That is, as described above, the braking wheel control has a strong effect of suppressing the drive wheel speed, and the response is about 10 times the response of the throttle control, and there is a large difference in the response of each control. If they are executed independently, the throttle control is affected by the brake control, and the throttle control is executed by the drive wheel speed fluctuated by the brake control. As a result, the throttle valve opens and closes in the opening direction and the closing direction. It takes time for hunting and for the drive wheel speed to converge to the target speed.

In order to solve such a problem, the applicant of the present application disclosed in Japanese Patent Application No. 63-46364, the control amount for executing the throttle control by the braking force of the braking device controlled by the brake control (that is, the brake hydraulic pressure). Therefore, it was proposed to correct the throttle opening so that the larger the brake oil pressure, the smaller the throttle opening. According to the proposed device, the control amount for the throttle control reflects the brake oil pressure of the brake device by the brake control, so that the throttle control and the brake control can be prevented from interfering with each other, and the drive wheel speed can be reduced. It is possible to quickly converge to the target speed.

By the way, in the above proposal, a so-called independent brake control system for individually controlling the slip state of the left and right drive wheels by brake control has not been studied in detail, and in such a control system, only the lower brake hydraulic pressure is used. The control amount of the throttle valve should be corrected.

However, if the above proposal is actually applied to an independent brake control system, simply correcting the control amount of the throttle valve using the lower brake oil pressure will not allow
It has been found that although good acceleration can be obtained when the vehicle accelerates from a low speed, running stability may be impaired when the vehicle is at a high speed for the following reasons.

That is, in the independent brake control system as described above, since the brake hydraulic pressure of the left and right drive wheels is individually controlled according to the slip state of each wheel, on a road surface having a different friction coefficient μ on the left and right drive wheels. The brake oil pressure on the road surface (low μ road) where the slip is easy to occur and the friction coefficient μ is low increases, and the brake oil pressure on the road surface (high μ road) where the slip is unlikely and the friction coefficient μ is high decreases. .

Therefore, when the above-described proposed device is applied to the independent brake control system and the control amount of the throttle valve is corrected by using a low brake hydraulic pressure of the left and right drive wheels, as shown in FIG. The output torque (engine torque) TE of the internal combustion engine 96 transmitted to the left and right drive wheels 94L and 94R via the gear 92 is high μ road side wheel 94L.
The driving torque of the vehicle on the high μ road side is the braking torque T by the brake control.
The slip rate at the high μ roadside wheel 94L is controlled to a value that can be controlled to a target slip rate at which optimal acceleration can be obtained by the PL and the engine torque TE, but the brake oil pressure of the low μ roadside wheel 94R is high. Since the brake hydraulic pressure of the μ road side wheel 94L is larger than the brake hydraulic pressure and the braking torque TPR is increased by the difference between the two brake hydraulic pressures, the driving torque of the vehicle on the low μ road side is increased by the braking torque TPR by the brake control and the engine torque TE. The driving torque on the μ road side is reduced by the difference between the left and right braking torques TPR and TPL.

When a difference occurs between the left and right driving torques, the rotational moment M acts on the center of gravity of the vehicle according to the torque difference. However, such a rotational moment M does not cause a problem when the vehicle is driven at a low speed. In addition, the vehicle can be driven by one wheel by the driving torque TL on the high μ road side where the slip is unlikely to occur, and the acceleration at the time of low-speed running of the vehicle, such as at the time of starting, is improved like the known differential limiting device. be able to. However, when a rotational moment is generated at the position of the center of gravity of the vehicle during high-speed running of the vehicle, the running stability of the vehicle may be impaired.

Accordingly, the present invention provides an apparatus for performing acceleration slip control by using both brake control and throttle control for independently controlling the brake oil pressure of the left and right drive wheels as described above, and provides an acceleration characteristic and a vehicle high speed The purpose of the present invention is to make it possible to quickly suppress the acceleration slip while ensuring both running stability during running.

[Means for Solving the Problems] That is, the present invention, which has been made to achieve the above object, has a first aspect.
As illustrated in the figure, driving wheel speed detecting means M1L, M1R for detecting the rotational speeds of the left and right driving wheels L, R of the vehicle, respectively, and the left and right driving wheels L, R detected by the driving wheel speed detecting means M1L, M1R. Control start condition determining means M2 for determining whether or not the start condition of the acceleration slip control is satisfied based on the rotation speed of the motor
When the control start condition determining means M2 determines that the start condition of the acceleration slip control is satisfied, the left and right drive wheels L, R
Respectively, by controlling the left and right braking devices BL and BR for applying braking force to the left and right wheels L and R via the differential device D, respectively. Control executing means M3 for executing an acceleration slip control for converging the rotational speeds of the left and right driving wheels L and R to respective target speeds.
A vehicle speed detecting means M4 for detecting a vehicle speed of the vehicle, and a braking force detection for detecting braking forces transmitted to the left and right driving wheels L and R by the acceleration slip control, respectively. Means M5L, M5R
If the vehicle speed detected by the vehicle speed detecting means M4 is equal to or higher than a predetermined value, the greater of the braking forces of the left and right drive wheels L, R detected by the braking force detecting means M5L, M5R Is used to correct the control amount of the throttle valve SB by the control execution means M3 so that the throttle opening decreases as the braking force increases. If the vehicle speed is less than a predetermined value, the braking force detection means By using the smaller one of the braking forces of the left and right driving wheels L and R detected by M5L and M5R, the throttle valve by the control execution means M3 so that the greater the braking force is, the smaller the throttle opening is.
And a throttle control amount correcting means M6 for correcting the control amount of the SB.

[Operation] In the acceleration slip control device of the present invention configured as described above, the control start condition determination means M2 is based on the rotational speeds of the left and right drive wheels L, R detected by the drive wheel speed detection means M1L, M1R. When it is determined that the conditions for starting the acceleration slip control have been satisfied, the control execution means M3 operates to drive the braking devices BL, BR provided on the left and right drive wheels L, R, and the throttle valve SB of the internal combustion engine EG, respectively. By controlling, the left and right drive wheels L, R
The acceleration slip control for converging the rotation speeds of the respective motors to the target speeds is started.

Next, the braking devices BL and BR of the left and right driving wheels L and R are driven by the acceleration slip control, and when a braking force is generated in each of these parts, the braking force is detected by the braking force detecting means M5L and M5R. Then, based on the detected braking force of each of the braking devices BL and BR and the vehicle speed detected by the vehicle speed detecting means M4, the throttle control amount correcting means M6 performs left-right drive if the vehicle speed is equal to or higher than a predetermined value. When the vehicle speed is less than a predetermined value, the smaller one of the braking forces of the left and right driving wheels L and R is selected, respectively. Then, the control amount of the throttle valve SB by the control execution means M3 is corrected so that the throttle opening decreases as the braking force increases.

That is, in the present invention, when the control amount of the throttle valve SB for performing the torque control of the internal combustion engine EG is at a low speed where the vehicle speed is less than a predetermined value, the closing direction is changed according to the braking force on the high μ road side on which slip is unlikely to occur. When the vehicle speed is higher than a predetermined value, the vehicle is corrected in the closing direction in accordance with the braking force on the low μ road where slip is likely to occur.

Therefore, on a road surface having different friction coefficients on the left and right, when the vehicle is running at a low speed, as shown in FIG.
Since the driving torque on the road is driven by a large driving torque determined by the engine torque TE suppressed by the braking force on the high μ road, the acceleration of the vehicle is ensured.

On the other hand, when the vehicle is running at a high speed, the engine torque is suppressed according to the slip state on the low μ road side by the braking force on the low μ road side. It is much smaller (TE'≪TE) than TE. Therefore, the acceleration slip on the high μ road side is suppressed by the decrease in the engine torque, and the braking torque TPL on the high μ road side becomes zero. Also low μ
The braking torque TPR on the roadside also becomes very small as the engine torque decreases. Therefore, as shown in FIG. 9 (b), the driving torques of the left and right driving wheels have substantially the same value determined by the engine torque TE '. As a result, no rotational moment is generated at the center of gravity of the vehicle, and the running stability of the vehicle is stabilized. Nature is secured.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

First, FIG. 2 shows a front engine engine to which the present invention is applied.
FIG. 1 is a schematic configuration diagram illustrating a configuration of an entire hydraulic brake device of a rear drive (FR) type vehicle.

This hydraulic brake device includes left and right rear wheels as driving wheels to which driving force from an internal combustion engine (not shown) is transmitted via a transmission, a propeller shaft, a differential gear, and the like.
2RL, 2RR, and wheel cylinders 4RL, 4RR, 4 of the braking device provided on the left and right front wheels 2FL, 2FR as idler wheels, respectively.
By supplying brake hydraulic pressure to FL and 4FR, each wheel 2R
L, 2RR, 2FL, and 2FR are used to suppress the rotation of the vehicle and brake the vehicle body. Normally, the brake hydraulic pressure generated in the two pressurizing chambers 8a and 8b of the master cylinder 8 by the depression of the brake pedal 6 is respectively reduced. , Front left and right wheel 2FL, 2FR wheel cylinder 4F
L, 4FR, and wheel cylinders 4RL, 4R for left and right rear wheels 2RL, 2RR
Supply to R to suppress rotation of each wheel.

Also, during such vehicle braking, an anti-skid control circuit (not shown) operates, and for each wheel 2RL, 2RR, 2FL, 2FR,
Anti-skid control is performed to prevent the wheels from locking and to control the brake hydraulic pressure so as to obtain an optimal braking force.

Then, next about this anti-skid control,
This is explained using 2RR as an example.

A proportioning valve 1 is provided in the hydraulic passage from the master cylinder 8 that supplies brake oil pressure to the wheel cylinder 4RR provided on the right rear wheel 2RR to the wheel cylinder 4RR.
0, a capacity control valve 12RR for anti-skid control is provided in series, and the capacity control valve 12RR and the wheel cylinder 4RR are communicated and shut off by opening and closing the first solenoid valve 14RR. The anti-skid control is performed in a state where the first solenoid valve 14RR is not excited and the wheel cylinder 4RR and the displacement control valve 12RR are in communication. 16RR is a check valve provided in parallel with the first solenoid valve 14RR.

The displacement control valve 12RR includes two pistons 18RR and 20RR disposed coaxially in the housing, and a piston 20R.
A variable volume chamber 22RR is formed in front of R (on the side of the piston 18RR), and brake hydraulic pressure supplied from the master cylinder 8 is supplied to the wheel cylinder 4RR via the variable volume chamber 22RR. Hydraulic chambers 24RR and 26RR are formed behind the pistons 18RR and 20RR, respectively, and a brake hydraulic pressure is supplied from a regulator 28. The regulator 28 converts a hydraulic pressure from an accumulator 34 that accumulates a discharge brake hydraulic pressure of a pump 32 driven by a pump drive motor 30 into a hydraulic pressure according to a brake operation amount. The hydraulic pressure from 28 is supplied, and the controlled hydraulic pressure is supplied to the other hydraulic chamber 26RR. The hydraulic chamber 26RR is switched between a state in which it communicates with the regulator 28, a state in which it communicates with the reservoir 40, and a state in which it does not communicate with either, by switching the electromagnetic direction switching valve 36RR and the electromagnetic on-off valve 38RR. This moves the piston 20RR while the piston 18RR is immobile,
The volume of the variable volume chamber 22RR is increased, maintained, and reduced in pressure.

The configuration of such an anti-skid control system consists of the left rear wheel 2RL,
The same applies to the left and right front wheels 2FL, 2FR. Therefore, corresponding parts are denoted by the same reference numerals and symbols RL, FL, FR representing the respective wheels, and detailed description thereof is omitted. The proportioning valve 10, the first solenoid valve 14, and the check valve 16 are not provided on the left and right front wheels 2FL and 2FR.

Next, each wheel 2RL, 2RR, 2FL, 2FR is provided with a speed sensor 42RL, 42RR, 42FL, 42FR for detecting the rotation speed, respectively, and the detection result is used for performing anti-skid control. Anti-skid control circuit (not shown) and acceleration slip control circuit for performing acceleration slip control described later
Output to 70 respectively. Then, the anti-skid control circuit calculates the acceleration, slip ratio, etc. of each wheel based on the input rotation speed of each wheel, so that the slip ratio of each wheel becomes the target slip ratio at which the braking force is obtained most. ,
A well-known anti-skid control process for driving and controlling the electromagnetic direction switching valve 36 and the electromagnetic on-off valve 38 is executed for each wheel.

Next, the first solenoid valve in the hydraulic passage that supplies brake hydraulic pressure to the wheel cylinders 4RL, 4RR of the left and right rear wheels 2RL, 2RR.
On the downstream side (wheel cylinder side) from 14RL and 14RR,
The capacity control valves 50RL and 50RR for acceleration slip control are connected respectively. Since these capacity control valves 50RL and 50RR have the same structure, the capacity control valve 50RR on the right rear wheel side is next.
Only the details are illustrated and described.

The capacity control valve 50 has a piston 52RR oil-tightly and slidably fitted in a housing 52RR, and hydraulic chambers 56RR, 5
A volume variable device 60RR in which 8RR is formed is provided. Hydraulic chamber 5
The 6RR is connected to the wheel cylinder 4RR, and is provided with a spring 62RR to urge the piston 54RR toward the hydraulic chamber 58RR.

The hydraulic chamber 58RR has a second solenoid valve 64RR and a third solenoid valve.
A solenoid valve 66RR is connected in series to
Together with the 60RR, a displacement control valve 50RR for acceleration slip control is configured. The second solenoid valve 64RR is switched between a state in which the oil flow is restricted and a state in which the oil flow is not restricted, and the third solenoid valve 66RR is switched between a state in which the hydraulic chamber 58RR is connected to the reservoir 40 and a state in which the hydraulic chamber 58RR is connected to the accumulator 34. Can be

By switching these solenoid valves 64RR and 66RR,
The hydraulic chamber 58RR has a state in which the hydraulic chamber 58RR communicates with the accumulator 34 with a sufficient flow passage area, a state in which the hydraulic chamber 58RR communicates through a throttle, and a state in which the reservoir 40RR is connected.
Is switched between a state in which communication is performed with a sufficient flow passage area and a state in which communication is performed through a throttle, whereby the volume of the hydraulic chamber 58RR is rapidly increased, gradually increased, gradually decreased, and rapidly decreased, and the piston 54RR is moved. As a result, the hydraulic pressure of the wheel cylinder 4RR is rapidly increased, gradually increased, gradually reduced, and rapidly reduced.

Next, the second and third solenoid valves 64RR and 66RR are used.
Is a second control valve provided in the displacement control valve 50RL on the left rear wheel 22RL side.
And the third solenoid valves 64RL and 66RL are switched by a control signal from the acceleration slip control circuit 70.

That is, the acceleration slip control circuit 70 includes the wheels 2RL, 2R
Speed sensor 42RL, 42RR, 42FL, 42F provided for R, 2FL, 2FR
R, a brake switch 72 that outputs an on / off signal according to the presence or absence of operation of the brake pedal 6, left and right rear wheels 2RL, 2RR
A rotational speed sensor 74 for detecting the rotational speed of the internal combustion engine that drives the engine, and a throttle position for detecting the opening of a main throttle valve 80 that opens and closes an intake passage 78 of the internal combustion engine when the vehicle driver operates an accelerator pedal 76. Sensor
82, the acceleration slip control circuit 70 detects the acceleration slip state of the left and right rear wheels 2RL, 2RR based on the detection signals from these sensors, and detects the displacement control valves 50RL, 50RR. By driving the second solenoid valves 64RL, 64RR and the third solenoid valves 66RL, 66RR provided therein, the acceleration slip control by the brake control is executed. When the acceleration slip control is performed by the brake control, the left and right first solenoid valves are used.
14RL and 14RR are closed and the wheel cylinders 4RL and 4
RR is shut off from the variable volume chambers 22RL and 22RR.

A drive motor 88 for driving a sub-throttle valve 86 provided in an intake passage 78 of the internal combustion engine is connected to the acceleration slip control circuit 70. The output torque of the internal combustion engine that drives the 2RL and 2RR is controlled.

Next, the acceleration slip control circuit 70, as shown in FIG.
The CPU 70a, the ROM 70b, the RAM 70c, and the like are configured as logical operation circuits, and are connected to an input port 70e and an output port 70f via a common bus 70d to perform input / output with the outside.

The detection signal from the above-described brake switch 72 is directly transmitted, and the detection signal from the throttle position sensor 82 is transmitted via an A / D converter 70h, and further, the rotation speed sensor 74 of the internal combustion engine and the wheels 2FL, 2FR, 2RL, 2RR. Speed sensor 42F provided in
Detection signals from L, 42FR, 42RL, 42RR are waveform shaping circuits 70i to 7
Each is input to the input port 70e via 0m.

In addition, the acceleration slip control circuit 70 includes left and right drive wheels 2RL,
2RR first solenoid valves 14RL, 14RR, 2nd solenoid valves 64RL, 64RR, 3rd solenoid valve 6
6RL, 66RR, a drive circuit for driving the drive motor 30 of the pump 32 and the drive motor 88 of the sub throttle valve 86, respectively.
70n to 70u are also provided, and the driving circuit 7 is provided via the output port 70f.
These components can be driven by outputting control signals to 0n to 70u.

Next, the acceleration slip control executed by the acceleration slip control circuit 70 configured as described above will be described with reference to the flowcharts shown in FIGS.

First, FIG. 4 is a flowchart showing a control amount calculation process for opening / closing control of the sub-throttle valve 86 which is repeatedly executed at predetermined time intervals.

As shown in the figure, when this process is started, first, step 100 is executed to calculate the vehicle body speed VF and the driving wheel VR based on the detection signals from the speed sensors 42FL to 42RR of each wheel. In this step 100, the average value of the left and right front wheel rotational speeds VFL, VFR obtained from the detection signals from the left and right front wheel speed sensors 42FL, 42FR or the larger value thereof is set as the vehicle speed VF. The driving wheel speed VR is set to the average value of the rotation speeds VRL, VRR of the left and right rear wheels obtained from the detection signals from the left and right rear wheel speed sensors 42RL, 42RR, or the larger one of them.

Next, in step 110, a target drive wheel speed VS is calculated from the calculated vehicle body speed VF using the following equation (1).

VS = a · VF (1) where a is a constant of 1 or more, and the target driving wheel speed VS
Is set so that the maximum frictional force is obtained between the drive wheel and the road surface, a value of about 1.12 to 1.20 is used in consideration of the slip ratio.

The target drive wheel speed VS may be calculated using the following equation (2) instead of the above equation (1).

VS = VF + b (2) Here, 0 <b.

Next, in step 120, it is determined whether or not the open / close control practical flag FS set at the start of the open / close control in a later-described process is in a reset state, that is, whether or not the open / close control of the sub throttle valve 86 is currently being executed. When it is determined that the open / close control execution flag FS is in the reset state and the open / close control is not being executed, the process proceeds to step 130.

In step 130, it is determined whether or not the execution condition of the opening / closing control is satisfied based on whether the main throttle valve 80 is not in the fully closed state and the driving wheel speed VR is equal to or higher than the target driving wheel speed VS. . If it is determined in step 130 that the opening / closing control execution condition is not satisfied, the process is temporarily terminated as it is, and if not, the process proceeds to step 140.

In step 140, it is determined whether or not a predetermined time (for example, 8 msec.) Has elapsed after the opening / closing control execution condition has been satisfied. If the predetermined time has not elapsed, the process ends. This is to prevent the execution of the opening / closing control of the throttle valve 86 by judging that an acceleration slip has occurred with respect to the instantaneous rotation fluctuation of the right and left rear wheels 2RL and 2RR due to unevenness of the road surface.

Next, when it is determined in step 140 that a predetermined time has elapsed after the opening / closing control execution condition is satisfied, the process proceeds to step 150 to set the opening / closing control execution flag FS, and then proceeds to step 160, where the rotation speed sensor 74 detects Based on the rotation speed NE of the internal combustion engine and the throttle opening θ, the correction coefficient K used to calculate the control amount s of the sub throttle valve 86 is obtained by interpolating from the map shown in FIG.

As shown in FIG. 8, the relationship between the throttle opening θ and the output torque of the internal combustion engine responds with good sensitivity at a low opening, and has little effect on the increase in torque from a medium opening to a high opening. This is to prevent the control amount of the sub-throttle valve 86 from becoming unnecessarily large and the responsiveness of control by the sub-throttle valve 86 from being reduced.

When calculating the correction coefficient K, the opening of the main throttle valve 80 (main throttle opening), such as at the start of control.
When θM is equal to or smaller than the opening of the sub throttle valve 86 (sub throttle opening) θS, the main throttle θM detected by the throttle position sensor 82 is used as the throttle opening θ, and the opening / closing control described later is executed. When the sub throttle opening θS becomes smaller than the main throttle opening θM after the start, the sub throttle opening θS obtained based on the control amount of the sub throttle valve 86 is used as the throttle opening θ.

When the correction coefficient K is obtained in this manner, the following step 17
The process proceeds to 0, and it is determined whether or not the vehicle is currently running at a high speed based on whether or not the vehicle speed VF obtained in step 100 is equal to or higher than a preset reference speed Vc. And this step 17
At 0, when it is determined that the vehicle speed is equal to or higher than the reference speed and the vehicle is traveling at a high speed, the process proceeds to the next step 190,
The control amount s of the sub-throttle valve 86 is calculated by the following equation (3): s = K ｛α ・ ΔV + β ・ Δ｝ -γ ・ MAX (PBCR, PBCL) (3), and the process is terminated once.

In the above equation (3), α is a proportional gain, β is a differential gain, ΔV is a difference (VS−VR) between the target driving wheel speed VS and the driving wheel speed VR, Δ is a time differential value thereof, and MAX (PBCR, PBC
L) Left and right rear wheels 2F controlled by brake control described later
The larger one of the brake oil pressures PBCL and PBCR of L and 2FR, and γ represents the correction coefficient. Further, the control amount s calculated by the above equation (3)
Is a time differential value of the auxiliary throttle opening command value θs, which is the target rotation speed of the drive motor 88 of the auxiliary throttle valve 86.

On the other hand, if it is determined in step 170 that the vehicle speed VF is lower than the reference speed Vc and the vehicle is traveling at a low speed, the process proceeds to step 200, and the control amount s of the sub throttle valve 86 is calculated by the following equation (4). S = K ｛α ・ ΔV + β ・ Δ｝ -γ ・ M | N (PBCR, PBCL) (4), and the process is terminated once.

In the equation (4), M | N (PBCR, PBCL) represents the smaller one of the brake hydraulic pressures PBCL, PBCR of the left and right rear wheels 2FL, 2FR controlled by the brake control described later. I have.

Next, if it is determined in step 120 that the opening / closing control execution flag FS is in the set state, that is, if the opening / closing control of the sub throttle valve 86 has already been executed, the process proceeds to step 210, and a sub-routine described later is executed. In the drive processing of the throttle valve 86, a flag that is set when the auxiliary throttle opening θS becomes equal to or less than the main throttle opening θM after the start of the opening / closing control.
It is determined whether Fo is set or not, and if the flag Fo is not set, the process directly proceeds to step 160.

If the flag Fo is set and the sub-throttle opening .theta.S once becomes equal to or less than the main throttle opening .theta.M after the start of the control, the routine proceeds to step 220, whereupon the sub-throttle opening .theta. It is determined whether or not it has become larger than θM. If θM ≧ θS, the process proceeds to step 160 again. If θM <θS, it is determined that there is no longer any acceleration slip on the rear wheels, and the flags FS and Fo are reset in steps 230 and 240. After that, the process is temporarily terminated.

Next, FIG. 5 is a flowchart showing a sub-throttle valve driving process executed at predetermined time intervals to open and close the sub-throttle valve 86 based on the control amount s calculated as described above.

When this process is performed as shown in the figure,
At 300, it is determined whether or not the opening / closing control execution flag FS is currently set. If the opening / closing control execution flag FS is set, the routine proceeds to step 310, where the sub throttle opening θS is set to the main throttle opening θM or less. It is determined whether or not. If θM <θS, the routine proceeds to step 320, where the drive motor is driven to rapidly close the sub-throttle valve 86.
After driving 88, the process is temporarily terminated.

On the other hand, if θM ≧ θS, the routine proceeds to step 330, where the flag Fo is set, and in the next step 340, the drive motor 88 is driven to open and close the sub throttle valve 86 according to the set control amount s. After that, the process is once ended.

Next, when it is determined in step 300 that the open / close control execution flag FS is in the reset state, the process proceeds to step 350, in which it is determined whether or not the sub throttle valve 86 is fully opened. This judgment is based on the auxiliary throttle opening θ
The determination is made based on whether S is equal to or greater than the maximum value θSMAX. If θS <θSMAX, the drive motor 88 is driven in step 360 to rapidly open the sub throttle valve, and then the process is temporarily terminated. If the valve 55 is fully open, the driving of the drive motor 88, that is, the sub-throttle valve 86 is stopped in step 370, and the process is temporarily terminated.

That is, in the present embodiment, when the acceleration slip of the rear wheel is detected based on the driving wheel speed VR and the control reference value VS, the opening / closing control of the sub-throttle valve 86 is started. Deviation ΔV and rear wheel brake oil pressure PBCL
Alternatively, when the opening degree θS of the sub-throttle valve 86 controlled based on the PBCR exceeds the main throttle opening degree θM, it is determined that the vehicle is in an operation state where it is not necessary to execute the acceleration slip control, and the sub-throttle valve 86 is determined. The opening / closing control is terminated.

Next, FIG. 6 is a flowchart showing the brake control executed by the acceleration slip control circuit 70, which is repeatedly executed at predetermined time intervals together with the control amount calculation processing of the auxiliary throttle valve.

When the process is started as shown in FIG.
It is determined whether or not the brake control execution flag FB set at the start of the execution of the brake control is in a reset state, that is, whether or not the brake control is currently in a non-execution state.

And when the brake control execution flag FB is in the reset state,
If the brake control is not currently being executed, the process proceeds to step 410, in which the brake switch 72 is in the off state, the brake operation is not performed by the vehicle driver, and the detection from the left and right rear wheel speed sensors 42RL, 42RR. It is determined whether or not the execution condition of the brake control is satisfied based on whether or not one of the rotation speeds VRL and VRR of the left and right rear wheels obtained from the signal is equal to or higher than the target rotation speeds VSL and VSR of the left and right rear wheels. I do. The target rotational speeds VSL and VSR are calculated by multiplying the rotational speeds VFL and VFR of the left and right front wheels obtained from the detection signals from the left and right front wheel speed sensors 42FL and 42FR by a preset slip ratio.

Then, in step 410, if it is determined that the execution condition of the brake control is not satisfied, the process is temporarily ended as it is, and if it is determined that the execution condition of the brake control is satisfied, the process proceeds to step 420, After setting the brake control execution flag FB indicating the execution of the brake control, the process proceeds to step 430.

In step 430, the brake control for the left rear wheel 2RL is executed as shown in the following table.

Here, the rotational acceleration of the left rear wheel, G1 represents a positive reference acceleration, G2 represents a negative reference acceleration, FU is a sudden increase in brake oil pressure, SU is a gradual increase in brake oil pressure, FD is a sudden decrease in brake oil pressure, SD indicates a moderate decrease in brake oil pressure.

That is, in step 430, the acceleration is calculated based on the rotation speed VRL of the left rear wheel. If the rotation speed VRL is equal to or higher than the target rotation speed VSL and the acceleration is equal to or higher than G2, the brake hydraulic pressure of the left rear wheel 2RL is increased. By lowering the brake oil pressure, the rotation speed of the left rear wheel 2RL is rapidly reduced. As described above, the control of the brake hydraulic pressure of the left rear wheel 2RL is performed by driving the first solenoid valve 14RL to a closed state and controlling the second solenoid of the displacement control valve 50RL.
And the third solenoid valves 64RL and 66RL are driven and controlled.

Then, in step 440, a value obtained by multiplying the integral ΣTPL of the pressure increase time TPL of the brake oil pressure to the left rear wheel 2RL by the processing of step 430 and the integral ΣTDPL of the pressure decrease time TDPL of the brake oil by the correction coefficient Kd (Kd · (ΣTDPL), the brake hydraulic pressure PBCL of the left rear wheel 2RL is calculated.

Next, at step 450, similarly to the brake control of the left rear wheel 2RL in step 430, the brake control for the right rear wheel 2RR is executed, and the routine proceeds to step 460, where the brake control for the right rear wheel 2RR by this brake control is performed. Integrated value of hydraulic pressure rise time TPRTPTPR and integrated value of pressure decrease time TDPRΣ
A brake hydraulic pressure PBCR for the right rear wheel 2RR is calculated from a deviation from the value obtained by multiplying the TDPR by the correction coefficient Kd (Kd · ΣTDPR).

Then, the brake control for each of the left and right rear wheels 2RL and 2RR is performed in this manner, and the left and right rear wheels 2RL and 2R are controlled by the brake control.
When the brake hydraulic pressures PBCL and PBCR of the R are calculated, the process proceeds to step 470, where the brake hydraulic pressures PBCL of the left rear wheel 2RL are determined.
Is determined to be less than or equal to 0, and the brake oil pressure P
If BC is 0 or less, the process proceeds to the next step 480, and it is determined whether or not the brake oil pressure PBCR of the right rear wheel 2RR has become 0 or less. In steps 470 and 480, the brake hydraulic pressures PBCL, PB of the left and right rear wheels 2RL, 2RR are determined.
When it is determined that both the CRs become values equal to or less than 0, the acceleration slip control by the brake control is determined to be ended, and the process proceeds to step 490, and after the brake control execution flag FB is reset, the process is temporarily ended. If not, the process ends once.

The correction coefficient Kd used to calculate the above-mentioned brake oil pressure
Is a coefficient used because the rate of change of the oil pressure is different between the pressure increase control and the pressure decrease control.

Thus, the brake control is performed for each of the left and right rear wheels 2RL and 2RR.
After the occurrence of the acceleration slip, it is repeatedly executed based on the wheel rotation speeds VRL, VRR until the brake oil pressure once increased becomes zero.

As described above, in this embodiment, when the vehicle speed is higher than or equal to the reference speed Vc and the vehicle is running at a high speed, the control amount s for controlling the opening / closing of the sub throttle valve 86 is set to the above-mentioned (3). According to the equation, the throttle closing direction is corrected in accordance with the larger one of the brake oil pressures PBCR and PBCL of the left and right rear wheels 2RL and 2RR controlled by the brake control, so that the vehicle speed VF is lower than the reference speed Vc. When the vehicle is running at a low speed, the control amount s for opening / closing control of the sub-throttle valve 86 is set to the brake hydraulic pressure PBCR of the left and right rear wheels 2RL and 2RR controlled by the brake control according to the above equation (4). The correction is made in the throttle closing direction according to the smaller brake oil pressure of the PBCL.

Therefore, according to the acceleration slip control device of the present embodiment,
When the vehicle is running at high speed, the drive torques of the left and right rear wheels can be made substantially the same as shown in FIG.
The traveling stability of the vehicle can be ensured to improve traveling safety, and when the vehicle is traveling at low speed, as shown in FIG. 9 (a), the driving torque on the high μ road side wheels where the brake hydraulic pressure becomes small is reduced. By maximizing, the acceleration of the vehicle can be ensured.

Here, in the above embodiment, simply the vehicle speed VF and the reference speed Vc
Is determined based on the vehicle speed, and the brake oil pressure for correcting the control amount s for the throttle control is switched. However, even when the vehicle speed is relatively low, when the vehicle makes a sharp turn, the running stability is reduced. In order to lower the vehicle speed, a sensor for detecting the turning angle of the vehicle (for example, a steering angle sensor for detecting the steering angle of the steering) is provided. The reference speed Vc may be changed to a lower value than during normal running, the vehicle speed may be determined based on the changed value, and the brake oil pressure for correcting the control amount s may be switched in the same manner as in the above embodiment. In this way, when the vehicle is turning sharply, the larger of the left and right brake hydraulic pressures is used as the brake hydraulic pressure for correcting the control amount s, even when the vehicle is operating at a relatively low speed. This makes it possible to improve the running stability when the vehicle turns sharply. When the turning angle (steering angle) of the vehicle is detected in this manner, the reference speed Vc is set so as to become smaller as the turning angle becomes larger in accordance with the detected turning angle. In this case, it is possible to optimally secure the acceleration during low-speed driving while ensuring the running stability when turning the vehicle.

[Effects of the Invention] As described in detail above, in the acceleration slip control device of the present invention, when the vehicle is running at low speed, the control amount of the throttle valve for performing the torque control of the internal combustion engine is controlled by the left-right drive controlled by the brake control. Correct the throttle closing direction according to the smaller of the braking forces of the wheels,
Conversely, when the vehicle is running at a high speed, the control amount of the throttle valve is corrected in the throttle closing direction in accordance with the greater of the braking forces of the left and right driving wheels to determine the control amount of the throttle valve. It has been like that. Therefore, according to the acceleration slip control device of the present invention, not only can the interference between the brake control and the throttle control be prevented and the control can be executed stably, but also the acceleration performance during low-speed running of the vehicle can be ensured. In addition, it is possible to improve the running safety of the vehicle by ensuring the running stability during high-speed running of the vehicle.

[Brief description of the drawings]

1 is a block diagram showing a configuration of the present invention, FIG. 2 is a schematic configuration diagram showing an overall configuration of a hydraulic brake device for a rear wheel drive vehicle according to an embodiment, and FIG. 3 is a block diagram showing a configuration of an acceleration slip control circuit. FIG. 4 is a flowchart showing a control amount calculating process of the sub throttle valve, FIG. 5 is a flowchart showing a driving process of the sub throttle valve, and FIG.
FIG. 7 is a flowchart showing brake control, FIG. 7 is an explanatory diagram showing a map for setting a correction coefficient K used for calculating a control amount of the sub-throttle valve, and FIG. 8 is a throttle opening and output of the internal combustion engine. FIG. 9 is a diagram illustrating a relationship with the torque, and FIG. 9 is an explanatory diagram for explaining a driving torque generated in the left and right driving wheels by the acceleration slip control. M1R, M1L: drive wheel speed detection means M2: control start condition determination means M3: control execution means, M4: vehicle speed detection means M5L, M5R: braking force detection means M6: throttle control amount correction means 2RL, 2RR: Rear wheel (drive wheel) 42RL, 42RR, 42FL, 42FR: Speed sensor 50RL, 50RR: Capacity control valve 70: Acceleration slip control circuit 86: Sub throttle valve

Claims (1)

(57) [Claims] A driving wheel speed detecting means for detecting rotation speeds of left and right driving wheels of a vehicle, respectively, and a condition for starting acceleration slip control is established based on the rotation speeds of the left and right driving wheels detected by the driving wheel speed detecting means. Control start condition determining means for determining whether or not the start condition of the acceleration slip control is satisfied by the control start condition determining means; And control for executing acceleration slip control for converging the rotational speeds of the left and right drive wheels to respective target speeds by controlling the drive of the throttle valves of the internal combustion engine that apply driving force to the left and right drive wheels via the differential device. And a vehicle speed detecting device for detecting a vehicle speed of the vehicle. The vehicle speed detecting device transmits the vehicle speed to the left and right driving wheels by the acceleration slip control. Braking force detecting means for detecting the braking force of each of the left and right driving wheels detected by the braking force detecting means when the vehicle speed detected by the vehicle speed detecting means is equal to or higher than a predetermined value. Using the larger one, the control amount of the throttle valve by the control executing means is corrected so that the throttle opening becomes smaller as the braking force is larger. If the vehicle speed is less than a predetermined value, the braking force is reduced. Using the smaller one of the braking forces of the left and right driving wheels detected by the detecting means, the control amount of the throttle valve by the control executing means is corrected such that the greater the braking force is, the smaller the throttle opening is. An acceleration slip control device for a vehicle, comprising: throttle control amount correction means;