JP2869661B2 - Vehicle slip control device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a slip control device for a vehicle, and more particularly, to a slip control device for a vehicle that can ensure the stability of the vehicle when turning. It is about.

(Prior Art) In a vehicle control device, when an excessive slip occurs between a drive wheel and its ground contact road surface at the time of starting or running of the vehicle, the slip is suppressed within a desired range, thereby driving the vehicle. Secure the driving force transmitted from the wheels to the road surface,
A vehicle slip suppression device configured to improve the starting performance or acceleration performance of the vehicle, secure a suitable frictional force between the drive wheels and the road surface, and improve the running stability or the steering stability of the vehicle. Known (for example, Japanese Patent Application Laid-Open No. 58-16 / 1983)
948 JP, JP-A-57-22948, JP-A-62-231836
Issue publication).

Such a slip control device includes an engine control unit that transiently lowers the engine output due to a reduction in the opening of a throttle valve, a delay in the ignition timing of the engine, or a fuel cut in the engine, and / or a brake fluid. Equipped with brake control means to transiently increase the braking force of the drive wheels by increasing the pressure, and excessive slip on the drive wheels due to idling of the drive wheels due to excessive depression of the accelerator on a road surface with a low friction coefficient In this case, the driving torque transmitted to the driving wheels by the engine control means and / or the brake control means is reduced so that the slip of the driving wheels converges to the target slip ratio or less. It was configured to ensure a desired coefficient of friction between them.

(Problems to be Solved by the Invention) However, the behavior characteristics of the vehicle with respect to the slip of the drive wheel are different between when the vehicle goes straight and when the vehicle turns.
The vehicle is in an unstable state when turning, which can cause a relatively large change in behavior due to a relatively slight slip of the drive wheels. However, since the slip control device is configured to regulate the driving torque transmitted to the drive wheels based on substantially the same or equivalent target slip ratio when the vehicle is traveling straight and turning, It was not possible to appropriately cope with changes in the behavior characteristics of the vehicle at the time, and as a result, it was not possible to properly secure the stability of the vehicle.

The present invention has been made in view of such a point, and a first object of the present invention is to provide a vehicle slip control device that can secure the stability of a vehicle during a turn.

It is a second object of the present invention to provide a vehicle slip control device that can ensure the stability of a vehicle during a turn without impairing the traveling performance of the vehicle during a turn.

(Means and Actions for Solving the Problems) In order to achieve the above object, a slip control device for a vehicle includes a slip detecting means for detecting a slip rate of a drive wheel, and a slip rate which is a predetermined target slip rate. A slip suppression means for suppressing the drive wheel slip by regulating the drive torque transmitted to the drive wheel so that the slip ratio of the drive wheel converges to at least the target slip ratio when the vehicle speed reaches And a steering angle detecting means for detecting a steering amount of the vehicle, wherein the slip suppressing means detects a yaw rate of the vehicle based on a detection result of the yaw rate detecting means and the steering angle detecting means. When a turning state is detected, a correction means for reducing the target slip ratio is provided. When the detection means detects a steering amount equal to or less than a predetermined value, the correction means reduces the target slip ratio by the first correction amount, and the yaw rate detection means detects a yaw rate equal to or more than the predetermined value,
When a steering amount exceeding a predetermined value is detected by the steering angle detecting means, the correcting means reduces the target slip ratio by a second correction amount set to be smaller than the first correction amount. .

According to the present invention having the above-described configuration, the slip suppressing unit suppresses the vehicle slip by the correcting unit when the turning state of the vehicle is detected based on the detection results of the yaw rate detecting unit and the steering angle detecting unit. The target slip rate, which is a reference for performing the correction, is corrected downward. Therefore, according to the slip control device of the present invention, since the target slip ratio is reduced during the turning of the vehicle, the slip of the drive wheels during the turning is suppressed more than when the vehicle is traveling straight, so that the cornering force of the vehicle is preferably reduced. As a result, the stability of the vehicle at the time of turning is improved.

Further, according to the present invention, the correction means reduces the target slip ratio relatively largely when the steering amount is relatively small despite the relatively large yaw rate. Therefore, the slip control device of the present invention is in a relatively unstable state in which the vehicle generates a turning performance equal to or more than a turning performance corresponding to the driver's steering, and a large change in behavior due to an increase in the slip of the drive wheels. When there is a tendency to cause the slip, the slip of the drive wheels is largely suppressed and controlled to secure the stability of the vehicle. On the other hand, when the yaw rate is relatively large and the steering amount is relatively large, the correction means decreases the target slip ratio by a relatively small amount. Therefore, the slip control device of the present invention suppresses the slip of the drive wheels slightly more than when the vehicle is traveling straight when the vehicle is in a state where the vehicle is going to make a large turn in a relatively stable state by the steering of the driver. Therefore, a desired driving force is ensured, the traveling performance of the vehicle is ensured, and the stability of the vehicle is improved.

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

FIG. 1 is a schematic overall configuration diagram of a vehicle provided with a vehicle slip control device according to an embodiment of the present invention. FIG.
2B, 2C, and 2D are explanatory views showing the cross-sectional structure and operation of the throttle opening adjustment mechanism shown in FIG.

In FIG. 1, a vehicle A has front wheels 1FL and 1FR as left and right driven wheels, and has rear wheels 1RL and 1RR connected to a drive system of the vehicle A as left and right driving wheels.

The drive system of the vehicle A includes an engine 2 mounted on the front of the vehicle body, an automatic transmission 3 connected to a crankshaft of the engine 2, a propeller shaft 4 connected to an output shaft of the automatic transmission 3, and a propeller shaft 4. The differential gear 5 is substantially constituted by a differential gear 5 connected to the rear end portion, and drive shafts 6L and 6R extending left and right from the differential gear 5 and connected to left and right rear wheels 1RL and 1RR, respectively.

A throttle valve 42 for controlling the amount of intake air is provided in an intake passage 41 of the engine 2.
42 is a throttle wire 112t, throttle opening adjustment mechanism
Accelerator pedal 43 via 44 and accelerator wire 112a
The throttle opening adjustment mechanism 44 is provided with a motor 106 for transiently lowering the throttle opening with respect to the accelerator opening.

The automatic transmission 3 is a hydraulically operated lock-up clutch.
It comprises a torque converter 11 having 11A and a transmission 12 provided with a multi-speed gear mechanism.
The lock-up clutch 11A of the torque converter 11 is connected to a solenoid 13 constituting a hydraulic control circuit of the automatic transmission 3.
The multi-speed gear mechanism of the transmission 12 is engaged or released by the selective excitation or demagnetization of b, and a plurality of solenoids constituting the hydraulic control circuit.
The shift operation is performed by the selective excitation or demagnetization of 13a.

The vehicle A also has brakes 21FL, 21FR, 21RL, 21RR disposed on the wheels 1FL, 1FR, 1RL, 1RR, brakes 21FL on the front wheel side, calipers 22FL, 22FR of the 21FR, and brake piping 23F.
Tandem type master cylinder 27 connected via L, 23FR, rear wheel side brakes 21RL, caliper 22RL, 22 for 21RR
There is provided a hydraulic booster type booster 26 connected to the RR via brake piping 23RL, 23RR, 33, and a brake device substantially constituted by a brake pedal 25 connected to the booster 26.

The master cylinder 27 applies the desired brake fluid pressure to the front wheel 1F.
L, 1FR, and converts the depressing force of the brake pedal 25 increased by the booster 26 into brake fluid pressure, and converts the brake fluid pressure into the first and second brake pressures of the master cylinder 27. Are supplied to brake cylinders provided in the calipers 22FL, 22FR via brake pipes 23FL, 23FR connected to the discharge ports 27a, 27b, respectively.

Relief pipelines 38FL and 38FR that can communicate with the reservoir tank 31 are connected to the brake pipes 23FL and 23FR, respectively, and each of the relief pipelines 38FL and 38FR functions as an outlet valve of an anti-lock brake system (ABS). Normally closed solenoid proportional on-off valve 37FL, 37
FR is inserted. FIG. 1 shows a state in which the on-off valves 37FL and 37FR are located at the fully closed position.

The booster 26 boosts the depressing force of the brake pedal 25 and transmits the boosted pressure to the master cylinder 27. The booster 26 uses the hydraulic pressure in the booster chamber (not shown) as a brake hydraulic pressure to form a brake pipe 33, It is configured to supply the brake cylinders provided on the calipers 22RL and 22RR via 23RL and 23RR. The booster chamber of the booster 26 is connected to a hydraulic pump 29 via a hydraulic supply pipe 28 to which an accumulator (not shown) is connected and connected.
The hydraulic pump 29 supplies the hydraulic fluid in the reservoir tank at a predetermined pressure, and holds the hydraulic fluid at a predetermined line pressure by a pressure accumulating operation of the accumulator. Further, a return pipe 30 for returning the hydraulic fluid discharged from the booster 26 to the reservoir tank 31 is connected to the booster 26.

Further, the boosting chamber of the booster 26 is connected to a brake pipe 33, and a normally open electromagnetic on-off valve 34 is inserted into the brake pipe 33, and a one-way valve 35 is connected to the on-off valve 34. They are connected in parallel. FIG. 1 shows the on-off valve 34.
Is shown in the fully open position.

The brake pipe 33 is connected to the right and left rear wheels 1R at the junction a.
It branches into brake pipes 23RL and 23RR for L and 1RR, and normally open electromagnetic proportional type on-off valves 36L and 36R are interposed in the brake pipes 23RL and 23RR, respectively. The brake pipes 23RL and 23RR are provided with relief pipes 38RL that can communicate with the reservoir tank 31 on the downstream side of the on-off valves 36L and 36R.
The 38RR branches off, and the normally closed electromagnetic proportional on-off valves 37RL and 37RR serving as outlet valves of the antilock brake system (ABS) are interposed in the relief lines 38RL and 38RR, respectively. In FIG.
The state where the on-off valves 37RL and 37RR are located at the fully closed position is shown.

A branch pipe 28a that can communicate with the pipe 28
And a normally closed electromagnetic on-off valve 32 is inserted in the branch pipe 28a. FIG. 1 shows a state where the on-off valve 32 is located at the fully closed position.

The vehicle A further controls an automatic transmission control unit UAT for controlling lock-up and a shift speed of the automatic transmission 3 by controlling solenoids 13a and 13b of a hydraulic control mechanism of the automatic transmission 3, and a vehicle. When braking A, each wheel 1F
Anti-lock brake system control means (hereinafter referred to as ABS control means) which works to maintain the desired frictional force between L, 1FR, 1RL, 1RR and the road surface and to secure the optimal braking force of vehicle A. And the rear wheels 1RL, 1 when the vehicle A is running or starting.
A slip control unit UTR including traction control means for suppressing a slip of the rear wheels 1RL and 1RR when an excessive slip occurs in the RR and securing a desired driving force of the rear wheels 1RL and 1RR. It has.

The automatic transmission control unit UAT has a throttle valve 42
A throttle sensor 61 for detecting the opening of the vehicle and a vehicle speed sensor 62 for detecting the vehicle speed based on the rotation speed of the propeller shaft 4
And the like are respectively input. The automatic transmission control unit UAT makes a lock-up determination and a shift determination based on the shift characteristics and the lock-up characteristics stored in advance based on the detection results of these sensors, and determines whether the solenoids 13a and 13b of the automatic transmission 3 have By outputting a control signal, lock-up control and shift control of the automatic transmission 3 are performed.

The slip control unit UTR includes the throttle sensor 61, the vehicle speed sensor 62, and the wheels 1FL, 1FR, 1R.
L, 1RR, wheel speed sensors 63, 64, 65, 66 for detecting the wheel speed of each wheel 1FL-1RR, accelerator pedal 43
Accelerator opening sensor 64 for detecting the amount of depression of
Motor rotation amount detection sensor 68 for detecting the rotation amount of motor 106, steering angle sensor 69 for detecting the steering amount of a steering wheel (not shown), manually operated slip control mode selection switch 70, brake pedal 25 Switch 71 for detecting depression of the vehicle, a G sensor 73 for detecting the vehicle deceleration of the vehicle A during braking, and the vehicle A
Yaw rate (angular velocity about the vertical axis of the vehicle)
Are detected by the yaw rate sensor 74 for detecting the load.

The slip control unit UTR has an input interface for receiving each signal from each of the above sensors, a ROM in which a predetermined control program and various maps are stored, a RAM provided with various memories necessary for executing control, and C
A microcomputer comprising a PU, an output interface for outputting a control signal to the automatic transmission control unit UAT, and each on-off valve 32, 34, 36L, 36R, 37FL,
A control circuit is provided for controlling the opening and closing of the 37FR, 37RL, and 37RR and for controlling the operation of the motor 106 of the throttle opening adjustment mechanism 44.

In the slip control unit UTR thus configured, the ABS control means includes an estimated vehicle speed calculated based on the vehicle deceleration detected by the G sensor 73;
Each wheel 1FL-1 detected by each wheel speed sensor 63-66
The slip state of each of the wheels 1FL to 1RR is detected from the difference between the RR and the wheel speed, and when it is determined that any of the wheels 1FL to 1RR has a tendency to lock, the on-off valve 37FL is used to cancel the tendency to lock the wheels. , 37FR, 37RL, 37RR by controlling the opening degree,
Brake pipe 23FL on the wheels that tend to lock,
It is configured to reduce the line hydraulic pressure of 23FR, 23RL, and 23RR. For example, at the time of braking, when the ABS control means detects that an excessive slip has occurred in the front wheel 1FL,
The opening and closing of the on-off valve 37FL is controlled so as to increase the opening degree of the on-off valve 37FL, whereby the line pressure of the brake pipe 23FL and the hydraulic pressure of the brake cylinder of the caliper 22FL are reduced, and the brake hydraulic pressure of the brake 21FL is reduced. Is transiently reduced. As a result, the front wheel 1FL is prevented from slipping, and a desired frictional force with the road surface is secured.
Front wheel 1FL, optimal braking force can be obtained.

Further, in the slip control unit UTR, the traction control means controls the rear wheels 1R when the vehicle A starts or runs.
L, 1RR, that is, engine control for transiently reducing the output of the engine 2 by controlling the amount of rotation of the motor 106 of the throttle opening adjustment mechanism 44 when excessive slip occurs in the drive wheels, and braking. A brake that regulates brake fluid pressure by controlling the opening and closing of the on-off valves 32 and 34 incorporated in the hydraulic circuit of the device and controlling the opening of the on-off valves 36L, 36R, 37FL, 37FR, 37RL, and 37RR. Control, whereby the drive torque transmitted to the rear wheels 1RL, 1RR is reduced, and the slip of the rear wheels 1RL, 1RR is suppressed.

In the engine control, the throttle opening adjusting mechanism 44 reduces the opening of the throttle valve 42 with respect to the accelerator opening of the accelerator pedal 43.
This is done by reducing the engine output.

The throttle opening adjustment mechanism 44 is, as shown in FIG.
An accelerator-side lever 112 connected to the accelerator pedal 43 via an accelerator wire 112a, a throttle wire 112t
The throttle-side lever 113 connected to the throttle valve 42 through the
A locking lever 114 having a locking portion 114a in contact with 12 and a locking portion 114b in contact with the throttle side lever 113 from the right in FIG. 2A, and is movable rightward in FIG. 2A. A drive lever 111 is disposed, a motor 106 for reciprocating the drive lever 111 in the left-right direction in the figure, and a stopper 123 for restricting the movement of the drive lever 111 to the left in the figure by a predetermined amount or more. Have been.

The throttle lever 113 is urged by a return spring 121 to the right in FIG. 2A, that is, in a direction in which the throttle valve 42 is closed.
The tension spring 116 interposed between the engagement portion 114a and the accelerator side lever 112 causes the engagement portion 114a
Are biased so as to contact the accelerator side lever 112, and the locking portion 114b is brought into contact with the throttle side lever 113 by a tension spring 122 interposed between the locking portion 114b and the throttle side lever 113. It is biased to abut. The urging force of the tension spring 116 is set to be larger than the urging forces of the tension spring 122 and the return spring 121.

2A and 2B, the drive lever 111 is
When located at the leftmost position, that is, the retreat position,
The throttle opening adjustment mechanism 44 includes an accelerator side lever 112,
Since the throttle side lever 113 and the locking lever 114 move integrally under the tension of the tension springs 116 and 122, the throttle opening of the throttle valve 42 is set to 0 to 0 in accordance with the accelerator depression amount of the accelerator pedal 42. It changes in the 100% range. FIG. 2A shows a state where both the accelerator opening and the throttle opening are 0%, and FIG. 2B shows a state where both the accelerator opening and the throttle opening are 75%. I have.

On the other hand, when the drive lever 111 is moved rightward in FIG. 2A by operating the motor 106, the throttle opening adjustment mechanism 44 moves the locking lever 114 to the left in the drawing to drive the drive lever 111. As shown in FIGS. 2C and 2D, the throttle opening of the throttle valve 42 is limited to an opening relatively smaller than the accelerator opening of the accelerator pedal 42. FIG. 2C shows a state where the accelerator opening and the throttle opening are 75% and 0%, respectively, and FIG. 2D shows a state where the accelerator opening and the throttle opening are 100% and 0%, respectively. A 25% condition is shown.

In addition, the above-described brake control moves the on-off valve 34 to the fully closed position,
Further, by switching the open / close valves 32 to the fully open position, the line pressure of the hydraulic pressure supply pipe 28 causes the brake pipe 23R
This is performed by raising the line pressure of L and 23RR and holding the line pressure by closing the on-off valves 36R and 36L, or releasing it by opening the on-off valves 37RL and 37RR.

FIG. 3 is a diagram showing, as a time chart, general wheel speed characteristics of rear wheels during traction control and the relationship between engine control and brake control by the traction control means. FIG. 4 is an explanatory diagram showing, in a block diagram, a circuit for determining a brake control target slip value and an engine control target slip value in order to set both target slip rates of the rear wheels. FIG. 5 is a diagram showing characteristics of a throttle opening lower limit control value for engine control set by the traction control means.

FIG. 3 shows one driving wheel of the vehicle A, for example, the left rear wheel 1R.
3 shows general wheel speed characteristics at the time of traction control in L, and the wheel speed characteristics at the time of traction control of the other drive wheel, for example, the right rear wheel 1RR, are also substantially the same as those shown in FIG. It has the same characteristics. Therefore, the following description regarding FIG. 3 is made assuming that the wheel speed characteristics of the left rear wheel 1RL are shown in FIG.

FIG. 3 shows the wheel speed of the left rear wheel 1RL during the slip control,
That is, the driving wheel speed VK _RL and the average value of the wheel speeds of the left and right front wheels 1FL and 1FR are indicated by solid lines with the driven wheel speed VJ, and the rear wheel 1RL is controlled by controlling the throttle opening. A threshold value a corresponding to the basic target slip ratio SE for engine control for regulating the slip ratio of the engine and a brake control for regulating the slip ratio of the rear wheel 1RL by controlling the brake fluid pressure. A threshold value b corresponding to the basic target slip ratio SB is shown. Note that the threshold value b is set to a value larger than the threshold value a.

Here, the slip ratio S _RL of the rear wheels 1RL is calculated by the following equation.

The basic target slip ratios SE and SB are calculated by the following equations.

Note that SET and SBT are a target slip value for engine control and a target slip value for brake control, which are commonly set for the rear wheels 1RL and 1RR, respectively.

The target slip value SET for engine control and the target slip value SBT for brake control are set such that the rear wheels 1RL and 1RR secure a desired driving force mainly when the vehicle A goes straight. As shown in FIG. 4, it is determined by the road surface maximum friction coefficient μmax, the vehicle speed, the accelerator opening, the steering wheel angle, and the running mode selected by the slip control mode selection switch 70.

In FIG. 4, a control unit UTR includes a basic value STBO of a brake control target slip value SBT and a basic value STAO of an engine control target slip value SET for each rear wheel 1RL, 1R.
R slip rate S _RL , S _RR whichever is greater,
Maximum friction coefficient μma of road surface estimated from driven wheel speed VJ
x is stored as a parameter in the map 81. In the map 81, the basic value STBO is set to a value larger than the basic value STAO. Each of the above target slip values SET, SBT
Is obtained by multiplying each of the basic values STAO and STBO by a correction gain coefficient KD. Above correction gain coefficient KD
Are various gains stored in the maps or tables 82, 83, 84, 85, respectively, that is, gain coefficients VG, ACPG, STRG, MODEG
The above-mentioned gain coefficient VG is for securing the stability of the vehicle A according to the increase in the vehicle speed, and is set by the map 82 based on the vehicle speed. Is for securing the driving force according to the driver's acceleration request, is set by the map 83 based on the accelerator opening, the gain coefficient STRG is
This is for ensuring the general stability of the vehicle A at the time of turning, is set by the map 84 based on the steering angle of the steering wheel, and the gain coefficient MODEG is determined by the table 85 manually selected by the driver. The setting is made based on the selection between the sport mode emphasizing traveling performance and the normal mode emphasizing stability.

In FIG. 3, the time point t ₁ earlier, a large slip on the rear wheel 1RL has not occurred, the throttle opening degree, the drive lever 111 of the throttle opening adjustment mechanism 44 is shown in Figures 2A and Figure 2B The basic throttle opening TH · B obtained in proportion to the accelerator opening by being held at the retreat position is set. The brake fluid pressure supplied to each of the brakes 21FL to 21RR is controlled by each of the on-off valves. 32, 34, 36R, 36L, 37FL
3737RR is held down at the normal position, so that the pressure is reduced.

Driving wheel speed VK _RL of the rear wheels 1RL, at time point t _1, has increased to the threshold a basic target slip ratio SE for engine control, the engine control by the slip control means is initiated at time point t ₁ , Slip control unit UTR
The traction control means includes a throttle opening adjustment mechanism 44.
By operating the motor 106, the drive lever 111 is moved forward, and thereby the throttle opening is reduced to the lower limit control value SM.
Feed-forward control is performed to reduce the speed at once.

As shown in FIG. 5, the throttle opening lower limit control value SM is stored as a map 91 using the vehicle speed and the road surface maximum friction coefficient μmax as parameters, and is determined based on the vehicle speed and the road surface maximum friction coefficient μmax. Is done. In FIG. 5, when μmax = 1, the friction coefficient is set to the smallest, and μmax = 5, the friction coefficient is set to the largest.
On road surfaces where max is relatively small, the lower limit control value SM
Is set to a relatively large value to promote an early output decrease of the engine 2, and on a road surface having a relatively large maximum friction coefficient μmax, the lower limit control value SM is set to a relatively small value.
The stall of the vehicle A due to an excessive decrease in the output of the engine 2 is avoided.

Traction control means, after once lower control value SM the throttle opening, so that the slip ratio S _RL of the rear wheels 1RL becomes the target slip ratio SE control engine throttle valve 42
Is feedback controlled. The feedback control is performed by the slip ratio S _RL of the rear wheels 1RL is to converge to the basic target slip ratio SE, controls the rotation of the motor 106 of the throttle opening adjustment mechanism 44, the throttle opening motor The opening degree regulated by 106, that is, the opening degree TH · M in FIG.

In FIG. 3, the driving wheel speed VK _RL of the rear wheels 1RL, despite the engine control is performed, in t ₁ after the time has further increased with respect to the driven wheel speed VJ, t ₂ time in driving wheel speed VK _RL of the rear wheels 1RL is increased to the threshold value b of the basic target slip ratio SB. The traction control means of the brake control unit UTR uses the drive wheel speed VK _RL
If There reaches a threshold b, so as to start the traction control by the braking control, the slip ratio S _RL of the rear wheels 1RL converges to the target slip ratio SB brake, brake line 28
On-off valves 32, 34, 36RL, 3 arranged at a, 33, 23RL, 38RL
Output a control signal to each of 7RR, brake 21RL of rear wheel 1RL
Is increased to the pressure Pn _RL , and the brake fluid pressure Pn _RL is maintained.

With this engine control and brake control, the rear wheel 1RL
The slip is suppressed, at t ₃ time, falls below a threshold c for the driving wheel speed VK _RL is corresponding to the basic target slippage ratio SB for controlling the brake slip control unit UTR is off valves 3
The brake fluid pressure is reduced by releasing 7RL, and the brake control is terminated.
The operation is continued until the possibility that the _SRL is increased disappears, that is, until the accelerator opening is fully closed.

Here, the driving force of the rear wheel 1RL generally tends to increase to a certain range as the slip ratio increases.
Since the cornering force of 1RL generally tends to decrease as the slip ratio increases, the stability of the vehicle A tends to be lost as the slip ratio increases. In this example, the basic target slip ratios SE and SB for the engine control and the brake control are determined by the steering angle sensor 69.
The yaw rate sensor 74 detects a yaw rate equal to or greater than a predetermined value based on the detection results of the yaw rate sensor 74 and the steering angle sensor.
When the steering amount equal to or less than the predetermined value is detected by 69, that is, when the vehicle A is in a relatively unstable turning state, the target slip rates SE and SB are set to the first target slip rate S.
E 'and SB' are respectively corrected, the yaw rate sensor 74 detects a yaw rate equal to or greater than a predetermined value, and the steering angle sensor 69 detects a steering amount exceeding a predetermined value, that is,
When the vehicle A is in a relatively stable turning state, the target slip ratios SE and SB are respectively corrected to second target slip ratios SE ″ and SB ″ which are set to be larger than the first target slip ratio. .

Therefore, when the vehicle A is in a relatively unstable turning state, the traction control means determines the slip ratio S of the rear wheel 1RL.
_{When RL} reaches the threshold values a 'and b' respectively defined by the first target slip ratios SE 'and SB', they start relatively early, respectively, and at the same time as the basic target slip ratios SE and SB. First target slip ratios SE ', SB' set to be small
Each to converge to a, and controls the output and brake hydraulic pressure of the engine 2, the slip ratio S _RL of the rear wheels 1RL are As is apparent from Figure 3 the driving wheel speed VK _RL indicated by the dashed line ' Is suppressed relatively early and without a large tendency to increase.

When the vehicle A is in a relatively stable turning state,
Traction control means, at the time the slip ratio S _RL of the rear wheels 1RL second target slip ratio SE ", SB" respectively by s defined is the threshold a ", the b" reaches the first target slip ratio SE , SB ', respectively, are started slightly later than the start times, and are set smaller than the basic target slip ratios SE, SB and larger than the first target slip ratios SE', SB '. Second target slip ratio SE ″, SB ″
Each to converge to a, and controls the output and brake hydraulic pressure of the engine 2, the slip ratio S _RL of the rear wheels 1RL is clear from the driving wheel speed VK _RL "indicated by the two-dot chain line in FIG. 3 In addition, there is a tendency that the vehicle is slightly suppressed as compared with the straight traveling without being extremely suppressed.

The wheel speed characteristics of the left rear wheel 1RL at the time of traction control have been described with reference to FIG. 3, but the target slip ratios SE and S for the right rear wheel are also similar to the left rear wheel 1RL.
Traction control by engine control and brake control is performed based on E ′, SE ″ and SB, SB ′, SB ″, and the characteristic of the drive wheel speed VK _RR of the right rear wheel 1RR during traction control is generally Similar to the wheel 1RL, the wheel speed characteristics shown in FIG. 3 are shown.

Note that when the friction coefficient of the ground contact road surface of the left rear wheel 1RL and the right rear wheel 1RR is different and the slip of one of the rear wheels 1RL or 1RR increases early, the engine control is performed on one of the wheels 1RL or 1RR.
It is started when the slip ratios S _RL , S _{RR of the RR} reach the target slip ratios SE, SE ′, SE ″ for engine control.
The brake control is configured as a so-called left / right independent control system. When each of the rear wheels 1RL, 1RR reaches a target slip ratio SB, SB 'or SB "for brake control, the target slip ratio is set. Are started for the rear wheels 1RL and 1RR, respectively.

Next, a method of controlling the slip control and the engine control by the brake control unit UTR will be described with reference to the flowcharts of FIGS.

FIG. 6 is a flowchart showing main control of traction control in the slip control unit UTR,
FIG. 7 is a flowchart illustrating a control method of engine control in the slip control unit UTR, and FIG. 8 is a flowchart illustrating a control method of brake control in the slip control unit UTR. The ninth
The figure is a flowchart showing a method of correcting the target slip ratio in the slip control unit UTR. The sixth
The symbol P in FIGS. 9 to 11 indicates a step.

The main control of the slip control in the slip control unit UTR will be described with reference to FIG.

First, a throttle sensor 61, a vehicle speed sensor 62, wheel speed sensors 63, 64, 65, 66, an accelerator opening sensor 67, a motor rotation amount detection sensor 68, a slip control mode selection switch 7
0, the detection results of the brake switch 71, the G sensor 73, and the yaw rate sensor 74 are read (P1).

Next, it is determined whether a failure has occurred in the slip control unit UTR (P2), and the slip control unit UTR is determined.
If no failure occurs, each rear wheel 1RL, 1RR, which is detected based on the wheel speed signals from the wheel speed sensors 63 to 66,
That is, the respective drive wheel speeds VK _RL and VK _{RR of} each drive wheel and the front wheel
1FL, 1FR, that is, the slip rates S _RL , S of the rear wheels 1RL, 1RR from the driven wheel speed VJ, which is the average value of the wheel speeds of the driven wheels, respectively.
_RR is calculated (P3).

Next, based on the detection result of the accelerator opening sensor 67, it is determined whether or not the accelerator opening is in a fully closed state (P4). If the accelerator opening is not fully closed, the actual driving of each drive wheel is performed. Either of the slip ratios S _RL and S _RR , whichever is greater, the _maximum slip ratio S _max and the basic target slip ratio SE for engine control
And the slip rate S _max is set to the basic target slip rate SE.
If so, the lower limit control value SM of the throttle opening is set (P6, 7), and the engine control is executed (P8).

In the engine control, as shown in FIG. 7, when it is determined that the slip ratio has increased and the slip ratio _Smax has reached the engine control target slip ratio SE (P11), the throttle opening Tn is reduced to a lower limit value. Set to SM, the motor 106 is operated via the control circuit of the motor 106 of the throttle opening adjustment mechanism 44 based on the lower limit value SM, and the throttle opening of the throttle valve 42 is adjusted by the throttle opening adjustment mechanism 44. Reduce to lower limit value SM (P11, 16).

In this way, once the opening of the throttle valve 42 is reduced to the lower limit value SM, the throttle opening Tn is thereafter
The throttle opening TH · M is set so that the slip ratio of the rear wheels 1RL and 1RR converges to the basic target slip ratio SE (P14).

As shown in FIG. 8, the slip control unit UT
R sets the basic target slip ratio SB for brake control during engine control (P9 (6th
Although the engine control is being executed, the slip rates S _RL and S _{RR of} the rear wheels 1RL and 1RR increase, and the slip rates S _RL and S _RR become the basic target slip rates, respectively. SB
When reached, the rear wheels 1RL, brake so that the slip ratio S _RL of 1RR, S _RR converges to the basic target slip ratio SB 21RL, 21RR
Set the brake fluid pressures Pn _RL and Pn _{RR respectively} (P22, 23)
On / off valves 32, 34, 36 based on the brake fluid pressures Pn _RL , Pn _RR
L, 36R, 37RL, via a control circuit for controlling the degree of opening of the 37RR, the on-off valve 32 to the fully open position, and also switches the on-off valve 34 to the fully closed position, the on-off valves 36L, 36R, 37RL, 37
Outputs a flow control signal to RR to apply brakes 21RL, 21
The brake fluid pressure at RR is determined by the brake fluid pressure Pn _RL , Pn
_{Adjust the} pressure to _{RR respectively} (P24). By adjusting the brake fluid pressure, the slip ratios S _RL and S _RR of the rear wheels 1RL and 1RR decrease, and when the slip ratios S _RL and S _RR fall below the basic target slip ratio SB, respectively, The brake control for 1RL and 1RR is completed (P22, 25), and the brake fluid pressure is released for the left and right rear wheels 1RL and 1RR, respectively.

Further, as shown in FIG. 9, the slip control unit UT
R corrects the target slip ratios SE and SB based on the yaw rate and the steering amount of the vehicle A, respectively, as described above.

First, the detection result Φ of the yaw rate sensor 74 and the detection result θ of the steering angle sensor 69 are read (P41), and the detected yaw rate Φ is equal to or larger than a predetermined value α, and the detected steering amount θ is set to a predetermined value. If it is equal to or less than β, the target slip ratios SE and SB are respectively corrected to first target slip ratios SE ′ and SB ′ obtained by reducing them to a predetermined ratio (a%, 100> a) (P42, 43). , 44).

When the detected yaw rate is equal to or more than a predetermined value α and the detected steering amount is equal to or more than a predetermined value β, the target slip rates SE and SB are set to a predetermined ratio (b%,
100>b> a) to reduce the first target slip ratio S
The second target slip ratios SE ″ and SB ″ are set to be larger than E ′ and SB ′, respectively (P42, 43, 45).

When the yaw rate is less than the predetermined value α, the slip control unit UTR does not correct the target slip rates SE and SB without correcting the target slip rates SE and SB because the vehicle A is substantially in a straight running state.
The above-described engine control and brake control are performed based on the target slip ratios SE and SB (P42, 46).

In the main control, the slip control unit UT
The failure or abnormality of the slip control unit UTR is detected by recognition of an abnormality in the storage means incorporated in the R, an inability to read from the ROM or an abnormality in the read value, or an inability to read or write to the RAM or an abnormality in the read value. In such a case, the slip control is stopped, the brake fluid pressure increased by the brake control is released, and the motor 106 is held at the reverse position to secure a throttle opening depending on the accelerator opening, and A failure signal is issued to the driver by an alarm lamp or an alarm buzzer. (P1
0, 11) The main control ends when the accelerator pedal 43 is released and the accelerator opening is fully closed (P1
2).

As described above, in the above embodiment, when the slip ratio of the rear wheels 1RL and 1RR reaches the basic target slip ratios SE and SB, the slip control unit UTR sets the slip ratio to the basic target slip ratios SE and SB. The drive torque transmitted to the rear wheels 1RL and 1RR is regulated so as to converge, and the basic target slip ratios SE and SB are corrected based on the detection results of the yaw rate sensor 74 and the steering angle sensor 69, and these basic slip rates are corrected. The target slip rate has been reduced. Accordingly, the slip of the drive wheels 1RL and 1RR during turning of the vehicle A is suppressed more than when traveling straight, so that the stability during turning of the vehicle A is improved.

When the yaw rate sensor 74 detects a yaw rate equal to or greater than a predetermined value, and the steering angle sensor 69 detects a steering amount equal to or less than the predetermined value, the slip control unit UTR determines the basic target slip ratios SE and SB. The basic target slip ratios SE and SB are corrected to the first target slip ratios SE ′ and SB ′, and when the yaw rate less than the predetermined value is detected and the steering amount exceeding the predetermined value is detected, The correction is made to the second target slip ratios SE ″ and SB ″ which are set to be larger than the first target slip ratios SE ′ and SB ′. Therefore, when the vehicle A has turned more than turning corresponding to the driver's steering and is relatively unstable, the rear wheels 1L
The slip of R and 1RR is greatly suppressed, and the stability of the vehicle is ensured. In addition, when the vehicle A is going to make a large turn in a relatively stable state by the steering of the driver,
The stability of the vehicle is secured without excessively suppressing the slip, that is, without impairing the traveling performance of the vehicle A.

As described above, the embodiments of the present invention have been described in detail. However, the present invention is not limited to the above-described embodiments, and needless to say, various changes can be made within the scope of the invention described in the claims. Absent.

For example, in the above embodiment, the yaw rate sensor detects the yaw rate of the vehicle. However, the yaw rate of the vehicle may be detected based on the steering amount detected by the steering angle sensor and the vehicle speed detected by the vehicle speed sensor. good.

In addition, the slip control unit UTR includes an ABS control unit. However, the present invention is, of course, applicable to a slip control device of a vehicle that does not include the ABS.

Further, in the above embodiment, the engine control is performed by controlling the throttle opening to reduce the output of the engine. However, the present invention provides a variable control of the ignition timing of the engine and / or the engine control. The present invention can also be applied to a slip control device that performs engine control so as to reduce engine output by fuel cut, or a slip control device that uses these engine control methods and an engine control method that controls throttle opening. is there.

Further, the control of the throttle opening may be performed by a step motor that opens and closes the throttle valve instead of the above-described throttle opening adjusting mechanism.

(Effects of the Invention) The present invention has the following effects by the above configuration.

According to the vehicle slip control device described in claim (1), it is possible to provide a vehicle slip control device that can ensure the stability of the vehicle when turning.

According to the vehicle slip control device described in claim (2), it is possible to provide a vehicle slip control device that can ensure the stability of the vehicle without impairing the traveling performance of the vehicle when turning. It becomes possible.

[Brief description of the drawings]

FIG. 1 is a schematic overall configuration diagram of a vehicle provided with a vehicle slip control device according to an embodiment of the present invention. 2A, 2B, 2C, and 2D are explanatory views showing the cross-sectional structure and operation of the throttle opening adjustment mechanism shown in FIG. FIG. 3 is a diagram showing, as a time chart, general wheel speed characteristics of rear wheels during traction control and the relationship between engine control and brake control by the traction control means. FIG. 4 is a graph for setting both target slip ratios of the rear wheels.
FIG. 4 is an explanatory diagram showing a block diagram of a circuit for determining a brake control target slip value and an engine control target slip value. FIG. 5 is a diagram showing characteristics of a throttle opening lower limit control value for engine control set by the traction control means. FIG. 6 is a flowchart showing main control of traction control in the brake control unit in FIG. FIG. 7 is a flowchart showing a control method of engine control in the slip control unit. FIG. 8 is a flowchart showing a control method of brake control in the slip control unit. FIG. 9 is a flowchart showing a method of correcting the target slip ratio in the slip control unit. 1FL, 1FR, 1RL, 1RR… Left front wheel, right front wheel, left rear wheel, right rear wheel, 2… engine, 3… automatic transmission, 4… propeller shaft, 5… differential gear, 6L, 6R …… Drive shaft, 21FL, 21FR, 21RL, 21RR …… Brake, 22FL, 22FR, 22RL, 22RR …… Caliper, 23FL, 23FR, 23RL, 23RR, 33 …… Brake piping, 25 …… Brake pedal, 26 …… Booster, 27 ... Master cylinder, 28 ... Hydraulic supply pipe, 28a ... Branch pipe, 29 ... Return pipe, 31 ... Reservoir tank, 32, 34, 36L, 36R, 37FL, 37FR, 37RL, 37RR ... On-off valve, 38FL, 38FR, 38RL, 38RR ... Relief pipeline, 41 ... Intake passage, 42 ... Throttle valve, 43 ... Accelerator pedal, 44 ... Throttle opening adjustment mechanism, 61 ... Throttle Sensor 62, Vehicle speed sensor 63, 64, 65, 66 Wheel speed sensor 67 Accelerator opening detection sensor 68 Rotation amount detection sensor, 69: Steering angle sensor, 70: Slip control mode selection switch, 71: Brake switch, 73: G sensor, 74: Yaw rate sensor, 106: Motor, 112a: Accelerator Wire, 112t… Throttle wire, UTR… Slip control unit, UAT… Automatic transmission control unit, a… Confluence, SE… Basic target slip ratio for engine control, SB… Basic for brake control Target slip rate.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Fumio Kageyama 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Inside the Mazda Corporation (72) Haruki Okazaki 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda (56) References JP-A-63-31859 (JP, A) JP-A-64-85862 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B60T 8/58

Claims (1)

(57) [Claims] 1. Slip detecting means for detecting a slip ratio of a drive wheel, and when the slip ratio reaches a predetermined target slip ratio, the slip ratio of the drive wheels converges at least to the target slip ratio. Slip suppression means for suppressing the slip of the drive wheels by regulating the drive torque transmitted to the drive wheels, a yaw rate detection means for detecting the yaw rate of the vehicle, and a yaw rate detection means for detecting the steering amount of the vehicle. A steering angle detection unit, wherein the slip suppression unit reduces the target slip ratio when a turning state of the vehicle is detected based on the detection results of the yaw rate detection unit and the steering angle detection unit. A yaw rate equal to or greater than a predetermined value is detected by the yaw rate detection means, and a steering amount equal to or less than a predetermined value is detected by the steering angle detection means. The correction means reduces the target slip ratio by a first correction amount, the yaw rate detection means detects a yaw rate equal to or greater than a predetermined value, and the steering angle detection means detects a steering amount exceeding a predetermined value. When the correction is made, the correction means reduces the target slip ratio by a second correction amount set to be smaller than the first correction amount.