JPH03227763A - Antiskid control device for vehicle - Google Patents

Abstract

PURPOSE:To improve the stability of a car at the time of pivoting by correcting downward a target slip ratio to be a standard for suppressing a vehicle slip when the turning state of the vehicle is detected on the detected results by a yaw rate detecting means and a steering angle detecting means. CONSTITUTION:When a vehicle is driven and an excessive slip is detected occurring on rear wheels 1RL, 1RR at the time of running or starting by the outputs of the respective wheel speed sensors 63-66 in slip control unit UTR, the output of an engine 2 is transiently reduced by controlling a throttle opening adjusting device 44 and simultaneously a breaking pressure is adjusted by controlling opening/closing valves 32, 34. In order that a wheel slip ratio may converge on a target slip ratio, the wheel slip ratio controls a driving torque to be transmitted to the rear wheels 1RL, 1RR. In this case, a steering angle sensor 69 and a yaw rate sensor 74 are provided for reducing the target slip ratio when the pivoting state of the vehicle is detected by those outputs.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a slip control device for a vehicle, and more specifically, to a slip control device for a vehicle that is capable of ensuring the stability of a vehicle when turning. It is related to the device.

(Prior art) A control device for a vehicle suppresses the slip within a desired range when excessive slip occurs between the drive wheels and the road surface they touch when the vehicle starts or runs. This ensures that the driving force is transmitted from the drive wheels to the road surface,
A slip control device for a vehicle is configured to improve the starting performance or acceleration performance of the vehicle, and to ensure a suitable frictional force between the drive wheels and the road surface to improve the running stability or steering stability of the vehicle. known (for example, JP-A-58-
16948, JP-A-57-22948, JP-A-62-231836, etc.).

Such slip control devices are engine control means that temporarily reduce engine output by reducing the throttle valve opening, retarding engine ignition timing, or cutting engine fuel, and/or brake fluid control means. Equipped with a brake control means that transiently increases the braking force of the drive wheels by increasing the pressure. Excessive acceleration on a road surface with a low coefficient of friction causes the drive wheels to spin and cause excessive slip. By reducing the drive torque transmitted to the drive wheels by the engine control means and/or brake control means, the slip between the drive wheels and the road surface is reduced so that the slip of the drive wheels converges to the target slip ratio or less. It was constructed to ensure the desired coefficient of friction between the two.

(Problem to be Solved by the Invention) However, the behavior characteristics of a vehicle with respect to the slip of the driving wheels are different when the vehicle is traveling straight and when the vehicle is turning. The slip is in an unstable state that can cause relatively large changes in behavior. However, the slip control device is configured to regulate the drive torque transmitted to the drive wheels based on substantially the same or equivalent target slip ratio when the vehicle is traveling straight and when turning. It was not possible to appropriately respond to changes in the behavior characteristics of the vehicle during turning, and as a result, it was not possible to suitably ensure the stability of the vehicle.

The present invention has been made in view of these points, and a first object thereof is to provide a slip control device for a vehicle that can ensure the stability of the vehicle when turning.

The present invention also provides the advantage that, without impairing the running performance of the vehicle when turning,
A second object of the present invention is to provide a slip control device for a vehicle that can ensure stability of the vehicle when turning.

(Means and Effects for Solving the Problems) The present invention has been made by focusing on the fact that the cornering force of a vehicle generally improves as the slip ratio of the vehicle decreases. In order to achieve the object, there is provided a slip detection 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 wheel is at least equal to the target slip ratio. A slip suppression means for suppressing slip of the drive wheels by restricting the drive torque transmitted to the drive wheels in a convergent manner; a yaw rate detection means for detecting the yaw rate of the vehicle; and a yaw rate detection means for detecting the amount of steering of the vehicle. and a steering angle detecting means for reducing the target slip ratio when the turning state of the vehicle is detected based on the detection results of the yaw rate detecting means and the steering angle detecting means. A slip control device for a vehicle is provided.

According to the above configuration of the present invention, the slip suppressing means includes:
When the turning state of the vehicle is detected based on the detection results of the yaw rate detection means and the steering angle detection means, the correction means downwardly corrects the target slip ratio, which is a reference for suppressing slip of the vehicle. Therefore, according to the slip control device, since the target slip ratio is reduced when the vehicle is turning, the slip of the driving wheels when turning is suppressed to a greater extent than when driving straight, so that the cornering force of the vehicle can be suitably controlled. This improves the stability of the vehicle when turning.

In order to achieve the second object, the present invention also provides that in the slip control device, the yaw rate detection means detects a yaw rate equal to or higher than a predetermined value, and the steering angle detection means detects a steering amount equal to or less than a predetermined value. When it is done,
The correction means reduces the target slip ratio by a first correction amount, and when the yaw rate detection means detects a yaw rate equal to or higher than a predetermined value and the steering angle detection means detects a steering amount exceeding a predetermined value. Further, there is provided a slip control device for a vehicle, wherein the correction means reduces the target slip ratio by a second correction amount that is set smaller than the first correction amount.

According to the above configuration of the present invention, the correction means reduces the target slip ratio by a relatively large amount when the steering amount is relatively small even though the yaw rate is relatively large.

Therefore, the slip control device described above is effective when the vehicle is in a relatively unstable state where the turning ability is greater than that corresponding to the driver's steering, and the increased slip of the drive wheels causes a large change in behavior. To secure the stability of a vehicle by greatly suppressing and controlling the slip of the driving wheels when there is a tendency that the slip may occur. On the other hand, when the yaw rate is relatively large and the steering amount is relatively large, the correction means reduces the target slip ratio by a relatively small amount. Therefore, the slip control device suppresses and controls the slip of the driving wheels to a slightly greater extent than when driving straight when the vehicle is about to make a large turn in a relatively stable state due to steering by the driver. , the desired driving force is ensured, the running performance of the vehicle is ensured, and the stability of the vehicle is improved.

(Examples) Hereinafter, examples of the present invention will be described with reference to the attached drawings.
Explain in detail.

FIG. 1 is a schematic overall configuration diagram of a vehicle equipped with a vehicle slip control device according to an embodiment of the present invention.

FIGS. 2A, 2B, 2C, and 2D are explanatory diagrams showing the cross-sectional structure and operation of the throttle opening adjustment mechanism shown in FIG. 1.

In FIG. 1, vehicle A has front wheels IFL and IFR as left and right driven wheels, and vehicle A has front wheels IFL and IFR as left and right driven wheels.
The rear wheels IRL and IRR are connected to the drive system of the vehicle.

The drive system of vehicle A is engine 2 mounted on the front of the vehicle body.
An automatic transmission 3 connected to the crankshaft of the engine 2, a propeller shaft 4 connected to the output shaft of the automatic transmission 3, a differential gear 5 connected to the rear of the propeller shaft 4, and a differential gear 5 connected to the rear of the propeller shaft 4. A drive shaft 6L extends left and right from the Lugia 5 and is connected to left and right rear wheels IRL and IRR, respectively.

It is approximately composed of 6R.

A throttle valve 42 for controlling the amount of intake air is disposed in the intake passage 41 of the engine 2, and the throttle valve 42 is connected to an accelerator via a throttle wire 119t, a throttle opening adjustment mechanism 44, and an accelerator wire 112a. The throttle opening adjustment mechanism 44 is connected to the pedal 43 and includes a motor 106 for transiently reducing the throttle opening relative to the accelerator opening.

The automatic transmission 3 has a hydraulically operated lock-up clutch 1.
It is comprised of a torque converter 11 having 1A and a transmission 12 equipped with a multi-speed gear mechanism. Lock-up clutch 11 of torque converter 11
A is engaged or released by selective excitation or demagnetization of the solenoid 13b that constitutes the hydraulic control circuit of the automatic transmission 3, and the multi-throw gear mechanism of the transmission 12 constitutes the hydraulic control circuit. A speed change operation is performed by selectively energizing or demagnetizing the plurality of solenoids 13a.

Vehicle A also has brakes 21FL, 21FR, and 21R disposed on each wheel IFLSIFR, IRL, and IRR, respectively.
L.

21PR1 front wheel brake 21F, 21PR caliper 22FL, 22FR and brake pipe 23PL,
Tandem type mask cylinder 27 connected via 23PR, rear wheel side brake 21RL, caliper 22RL of 21RR, 22RR and brake pipe 23R, 2
The brake system includes a hydraulic booster type booster 26 connected via 3RR and 33, and a brake pedal 25 connected to the booster 26.

The mask cylinder 27 applies desired brake fluid pressure to the front wheel IF.
L, IFH, and booster 26
Converts the increased depression force of the brake pedal 25 into brake fluid pressure, and sends the brake fluid pressure through brake pipes 23FL and 23PR connected to the first and second discharge ports 27a127b of the mask cylinder 27, respectively. hand,
It is configured so as to be supplied to the brake rings provided on the mirrors 22FL and 22FR, respectively.

Relief pipes 38FL and 38FR, which can communicate with the reservoir tank 31, are connected to the brake pipes 23FL and 23PR, respectively.

A normally closed electromagnetic proportional on-off valve 37F, which functions as an outlet valve for an anti-lock brake system (ABS), is inserted into each of the 38FRs. FIG. 1 shows a state in which the on-off valve 37F and 37FR are in the fully open position.

The booster 26 boosts the depression force of the brake pedal 25 and transmits it to the mask cylinder 27, and uses the hydraulic pressure in the booster chamber (not shown) as the brake hydraulic pressure in the brake piping 33. Caliper 2 via 23RL and 23RR
It is configured to be supplied to brake cylinders provided in 2RL and 22RR, respectively. The boosting 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. By the pressure pump 29,
The hydraulic fluid in the reservoir tank is supplied at a predetermined pressure, and is maintained at a predetermined line pressure by the pressure accumulating action of the accumulator. The booster 26 also has a reservoir tank 31 for storing the hydraulic fluid discharged from the booster 26.
A return piping 30 is connected to return the water.

Further, the boost chamber of the booster 26 is connected to a brake pipe 33, and a normal oven type 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. connected in parallel. FIG. 1 shows the on-off valve 34 in a fully open position.

The brake pipe 33 branches into brake pipes 23R and 23RR for the left and right rear wheels IRL and IRR at the confluence part a, and the brake pipes 23RL and 23RR include:
Normally open type electromagnetic proportional on/off valve 36L, 36R
are inserted respectively. Brake pipe 23RL, 2
3RR is a relief pipe 38RL that can communicate with the reservoir tank 31 on the downstream side of the on-off valves 36L and 36R;
38RR are branched respectively, and relief pipe 38RL
, 38RR is equipped with an anti-lock brake system (AB
Normally closed type electromagnetic proportional on-off valves 37RL and 37RR, which function as outleft valves of S), are inserted, respectively. FIG. 1 shows a state in which the on-off valves 37RL and 37RR are in the fully closed position.

The confluence part a also includes a branch pipe 28 that can communicate with the pipe 28.
A normally closed electromagnetic on-off valve 32 is inserted into the branch pipe 28a. FIG. 1 shows the on-off valve 32 in a fully closed position.

The vehicle A further controls the automatic transmission 3 by controlling the solenoids 13a and 13b of the hydraulic control mechanism of the automatic transmission 3.
(control unit for automatic transmission for controlling lock-up and gear position) UAT, $, and vehicle, when braking,
Each wheel IFL, IFR, IRL.

Vehicle A maintains the desired frictional force between the IRR and the road surface.
anti-lock brake system control means (hereinafter referred to as AB3 control means) that operates to ensure the optimum braking force of the rear wheels IRL and IRR when the vehicle A is running or starting.
When excessive slip occurs in the rear wheels IRL, IR
The slip control unit (UTR) is equipped with a traction control unit (UTR) that suppresses slip of the rear wheels IRL and traction control means that works to secure the desired driving force of the rear wheels IRL and IRR.

Control unit for automatic transmission) UAT includes throttle valve 4.
Detection signals from a throttle sensor 61 that detects the opening degree of the propeller shaft 2 and a vehicle speed sensor 62 that detects the vehicle speed based on the rotational speed of the propeller shaft 4 are manually inputted. Based on the detection results of these sensors, the automatic transmission control unit UAT performs lock-up determination and shift determination based on pre-stored shift characteristics and lock-up characteristics, and sends control signals to the solenoids 13a and 13b of the automatic transmission 3. is output to perform lock-up control and shift control of the automatic transmission 3.

In addition, the slip control unit (UTR) includes the throttle sensor 61, the vehicle speed sensor 62, and the IFLSI of each wheel.
Provided at FR1IRL and IRR, each wheel IFL~IR
Wheel speed sensors 63, 64 for detecting wheel speeds of H.
65.66, an accelerator opening sensor 67 for detecting the amount of depression of the accelerator pedal 43, a motor rotation amount detection sensor 68 for detecting the rotation amount of the motor 106, and a steering amount of the steering wheel (not shown). a steering angle sensor 69, a manually operated slip control mode selection switch 70, a brake switch 71 for detecting depression of the brake pedal 25, a G sensor 73 for detecting the deceleration of the vehicle during braking, The detection results of the yaw rate sensor 74 for detecting the yaw rate of the vehicle A (the angular velocity around the vertical axis of the vehicle body) are input manually.

The slip control unit UTR is equipped with a human interface that receives each signal from each sensor, a ROM that stores predetermined control programs and various maps, and various memories necessary to execute control. RAM
, and a microcomputer consisting of a CPU, 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, 37FR, 37RL, 37
The control circuit includes a control circuit that controls the opening and closing of the RR and controls the operation of the motor 106 of the throttle opening adjustment mechanism 44.

In the slip control unit (UTR) configured in this way, the ABS control means uses the estimated vehicle speed calculated based on the vehicle deceleration detected by the G sensor 73 and the wheel speed sensors 63 to 66. Each wheel IF is determined from the difference between the detected wheel speeds of each wheel IFL and IRR.
Detects the slip condition of wheels IFL~IRR
When it is determined that one of the wheels R has a locking tendency, the on-off valve 37FL,
By controlling the opening degrees of 37FR137RL and 37RR, the brake pipe 23FL for the wheel that has a tendency to lock,
5) For example, during braking, the above
When the A B S control means detects that excessive slip has occurred in the front wheel IFL, it performs Denity control on the on-off valve 37FL so as to increase the opening degree of the on-off valve 37FL, thereby causing the line of the brake piping 23FL to The pressure and the hydraulic pressure of the brake cylinder of the caliper 22FL are lowered to transiently lower the brake hydraulic pressure of the brake 21FL. As a result, the slip of the front wheel IFL is suppressed and the desired frictional force with the road surface is secured, so that the front wheel IFL can obtain an optimal braking force.

In the slip control unit (UTR), the traction control means controls the throttle opening adjustment mechanism 44 when excessive slip occurs in the rear wheels IRL, IRR1, that is, the drive wheels, when the vehicle starts or runs. motor 10
Engine control that transiently reduces the output of the engine 2 by controlling the amount of rotation of the engine 6, and controls the opening and closing of the on-off valves 32 and 34 incorporated in the hydraulic pressure circuit of the brake device, as well as on-off valves 36L and 36R137FL. ,37F
R.

By controlling the opening degrees of 37RL and 37RR, brake control is performed to adjust the brake fluid pressure, thereby reducing the drive torque transmitted to the rear wheels IRLSIRR and suppressing the slip of the rear wheels IRL and IRR. is configured to do so.

The engine control is performed by reducing the opening degree of the throttle valve 42 relative to the accelerator opening degree of the accelerator pedal 43 by the throttle opening adjustment mechanism 44, thereby reducing the engine output of the engine 2.

As shown in FIG. 2A, the throttle opening adjustment mechanism 44 connects the accelerator pedal 43 via an accelerator wire 112a.
an accelerator-side lever 112 connected to the throttle valve 42 via a throttle wire 112t, a throttle-side lever 113 connected to the throttle valve 42 via a throttle wire 112t, and a locking portion 11 that abuts the accelerator-side lever 112 from the right side in FIG. 2A.
4a and a locking portion 114b that contacts the throttle side lever 113 from the right in FIG. 2A, a drive lever 111 disposed so as to be movable in the right direction in FIG. 2A, and a drive It is generally composed of a motor 106 that reciprocates the lever Ill in the left-right direction in the figure, and a stopper 123 that restricts movement of the drive lever 111 to the left in the figure beyond a predetermined amount.

The throttle side lever 113 is biased to the right in FIG. 2A by the return valve IJ song 21, that is, in the direction in which the throttle valve 42 closes, and the locking lever 114 is biased between its locking portion 114a and the accelerator. A tension spring 116 interposed between the side lever 112 causes the locking R114a to be connected to the accelerator side lever 112.
The above-mentioned lock fls
114b and the throttle side lever 113, the locking portion 114b is
is urged so as to come into contact with the throttle side lever 113. Note that the biasing force of the tension spring 116 is
Tension spring 122 and return spring 121
is set larger than the urging force of.

As shown in FIGS. 2A and 2B, the drive lever 111
is located in the leftmost position, that is, in the reverse position, the throttle opening adjustment mechanism 44 moves the accelerator side lever 112, the throttle side lever 113, and the locking lever 11.
4 move integrally under the tension of the tension springs 116, 122, the throttle opening of the throttle valve 42 varies in the range from 0 to 100%, depending on the amount of depression of the accelerator pedal 42. In addition, the second
In diagram A, both accelerator opening and throttle opening are 0%.
FIG. 2B shows a state where both the accelerator opening and the throttle opening are 75%.

On the other hand, when the motor 106 is operated to advance the drive lever 111 to the right in FIG. Therefore, as shown in FIGS. 2C and 2D, the throttle opening Jf of the throttle valve 42 is limited to a relatively smaller opening than the accelerator opening of the accelerator pedal 42. Note that FIG. 2C shows states where the accelerator opening and throttle opening are 75% and 0%, respectively, and FIG. 2D shows states where the accelerator opening and throttle opening are 100%, respectively.
and 25% conditions are shown.

In addition, the above-mentioned brake control sets the on-off valve 34 to the fully open position,
Further, by switching the on-off valves 32 to the fully open position, the line pressure of the brake pipes 23RL and 23RR is increased by the line pressure of the hydraulic pressure supply pipe 28, and this line pressure is maintained by closing the on-off valves 36R136L. Or, on-off valves 37RL, 37RR
This is done by releasing by opening.

FIG. 3 is a diagram showing, as a time chart, the relationship between the general wheel speed characteristics of the rear wheels during traction control and the 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 target slip value for brake control and a target slip value for engine control in order to set both target slip ratios for the rear wheels. The figure is a diagram showing the characteristics of the throttle opening lower limit control value for engine control set by the traction control means.

FIG. 3 shows one driving wheel of vehicle A, for example, the left rear wheel IR.
This shows general wheel speed characteristics during traction control in L, and indicates the other drive wheel, for example, the right rear wheel IRR.
The wheel speed characteristics during traction control are also substantially the same as those shown in FIG. Therefore, the following explanation regarding FIG. 3 will be made assuming that FIG. 3 shows the wheel speed characteristics of the left rear wheel IRL.

Figure 3 shows the wheel speed of the left rear wheel IRL during slip control,
That is, the driving wheel speed VKIL, the left and right front wheels IF, and the IF
The average value of each wheel speed of R and the driven wheel speed VJ are shown by a solid line, and the engine control function is to regulate the swive ratio of the rear wheels IRL by controlling the throttle opening. By controlling the brake fluid pressure and the threshold value a corresponding to the basic target slip ratio SE for the rear wheel IRL
A threshold value corresponding to the basic target slip rate SB for brake control for regulating the slip rate of the vehicle is shown. Note that the threshold value S is set to a larger value than the threshold value a.

Here, the slip ratio 5ILL of the rear wheels IRL is determined by the following equation.

Further, each of the basic target slip rates SE and SB is calculated using the following formulas.

Driven wheel speed VJ Note that SET and SBT are rear wheel lRL and IR, respectively.
These are a target slip value for engine control and a target slip value for brake control that are commonly set for H.

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

In FIG. 4, the control unit (UTR) contains the basic value 5TBO of the target slip value SBT for brake control, the basic value S T , A of the target slip value SET for engine control,
O is the slip rate of each rear wheel IRL, IRR 5ILS
sill, whichever is larger, and the driven wheel speed VJ
The maximum friction coefficient μmax of the road surface estimated from is stored in the map 81 as a parameter, and the map 81
In 51, the basic value 5TBO is set to a larger value than the basic value STA○. Each target slip value 5ETSSBT is obtained by multiplying each basic value 5TAoSSTBO by a correction gain coefficient KD. The above correction gain coefficient KD can be obtained from the map or table 82.
．． Various gains stored in 83, 84, and 85, ie, gain coefficients VGSACPG and 5TRG.

The gain coefficient VG is obtained by multiplying the MODEG values, and the above gain coefficient VG is to ensure the stability of the vehicle A as the vehicle speed increases, and is set by the map 82 based on the vehicle speed. The coefficient, 8CPG, is to ensure the driving force that corresponds to the driver's acceleration request, and is set by the map 83 based on the accelerator opening degree, and the gain coefficient, 5TRG, is to ensure the driving force that corresponds to the driver's acceleration request. The gain coefficient MODEC is set by the map 84 based on the steering wheel angle, and the gain coefficient MODEC is set by the table 85 which is manually selected by the driver. It is set based on the selection of normal mode with emphasis on stability.

In Fig. 3, before time t1, no large slip has occurred in the rear wheel IRL, so the throttle opening is
The drive lever 111 of the throttle opening adjustment mechanism 44 is
By being held in the backward position shown in Figures A and 2B, the basic throttle opening TH-B is set in proportion to the accelerator opening, and each brake 21F
The brake fluid pressure supplied to 21RR is
2.34.36R, 36L, and 37FL to 37RR are held at the normal position, thereby lowering the voltage.

The driving wheel speed VKRL of the rear wheels IRL is 1. At this point in time, the basic target slip ratio SE for engine control has increased to the threshold value a, and the engine control by the upper slip control means is 1. The traction control means of the slip control unit (UTR) operates the motor 106 of the throttle opening adjustment mechanism 44 to
The drive lever 111 is moved forward, thereby causing the slow
Feedforward control is performed to reduce the valve opening degree all at once to the lower limit control value SM.

As shown in FIG. 5, the throttle opening lower limit control value SM is stored as a map 91 that uses the vehicle speed and the maximum friction coefficient μmaX of the road surface as parameters, and is determined based on the vehicle speed and the maximum friction coefficient μmaX of the road surface. be done. In Figure 5, μmax = 1 has the smallest friction coefficient, μm
The friction coefficient is set to be the largest when ax=5, and on a road surface where the maximum friction coefficient μmax is relatively small, the lower limit control value SM is set relatively large to encourage an early output reduction of the engine 2, and On a road surface where the maximum friction coefficient μmax is relatively large, the lower limit control value SM is set relatively small to avoid stalling of the vehicle A due to an excessive decrease in the output of the engine 2.

The traction control means once sets the throttle opening to the lower limit control point SM, and then performs feedbank control on the opening of the throttle valve 42 so that the slip ratio 5ILL of the rear wheel IRL becomes the target slip ratio SE for engine control. This feedback control is performed by controlling the rotation of the motor 106 of the throttle opening adjustment mechanism 44 so that the slip ratio SRL of the rear wheels IRL converges to the basic target slip ratio SE, and the throttle opening is controlled by the motor 106. The opening degree regulated by, that is, the opening degree TH・M in Fig. 3
becomes.

In FIG. 3, the driving wheel speed VKRL of the rear wheel IRL is
Despite the engine control being performed, after time t3, the driven wheel speed VJ further increases, and at time t2, the driving wheel speed VKIL of the rear wheels IRL exceeds the basic target slip ratio SB. Threshold value is increasing. The traction control means of the brake control unit UTR starts traction control by brake control when the driving wheel speed V K I L reaches the threshold value, and the slip rate SRL of the rear wheel IRL reaches the target slip rate SB for the brake. The brake pipes 28a, 33.
Opening/closing valves 32, 34, located at 23RL and 38RL.
36R and 3? Outputs a control signal to each of the RR and controls the rear wheel I.
RL brake 21. RL brake fluid pressure as pressure PnR
While increasing the brake fluid pressure to L, the brake fluid pressure PnRL is maintained.

Through such engine control and brake control, the rear wheel IRL
slip is suppressed, and at time t3, the drive wheel speed V K
RL is at the basic target slip rate SB for brake control.
When the slip rate falls below the threshold value C, the slip control unit UTR lowers the brake fluid pressure by opening the on-off valve 37RL and ends the brake control, but the engine control increases the slip rate SIL. This continues until the possibility disappears, that is, until the accelerator opening is fully closed.

Here, the driving force of the rear wheels IRL generally tends to increase to the extent that the slip ratio increases, but the cornering force of the rear wheels IRL generally decreases as the slip ratio increases. Therefore, vehicle A tends to lose its stability as the slip ratio increases. In this example, the basic target slip ratios SE and SB for engine control and brake control are adjusted downward based on the detection results of the steering angle sensor 69 and the yaw rate sensor 74. , when the yaw rate sensor 74 detects a yaw rate greater than a predetermined value and the steering angle sensor 69 detects a steering amount less than the predetermined value, that is, when the vehicle A is in a relatively unstable turning state, each of the above targets is The slip ratios SE and SB are respectively corrected to the first target slip ratios SE' and SB', and the yaw rate sensor 74 detects a yaw rate equal to or higher 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 rates SE and SB are set to a second target slip rate SE'SB' that is set larger than the first target slip rate. Each is corrected.

Therefore, when the vehicle A is in a relatively unstable turning state, the traction control means sets a threshold value a' at which the slip ratio SRL of the rear wheels IRL is determined by the first target slip ratio SE'SB', When b' is reached, the engine 2 is started relatively early and converged to the first target slip ratio SE'SB' which is set smaller than the basic target slip ratio 5ESSB. Since the output and brake fluid pressure are controlled, the slip ratio SRL of the rear wheels IRL shows a relatively early and large increasing tendency, as is clear from the drive wheel speed VKRL' shown by the dashed line in Fig. 3. Suppressed without showing.

Further, when the vehicle A is in a relatively stable turning state, the traction control means controls the slip rate SIL of the rear wheels IRL.
reaches the thresholds a' and b' determined by the second target slip ratios SE' and SB', respectively, and the slip ratios are slightly lower than the point at which they were started by the first target slip ratios SE' and SB'. The second target slip ratios SE', SB' are respectively started with a delay and are set smaller than the basic target slip ratios SE, SB and larger than the first target slip ratio SE'SB'. Since the output of the engine 2 and the brake fluid pressure are controlled so as to converge to
It is not extremely suppressed, but tends to be suppressed slightly more than when driving straight.

The wheel speed characteristics of the left rear wheel IRL during traction control have been explained above with reference to FIG. 3. Similarly to the left rear wheel IRL, the target slip ratio SE,
Traction control is performed by engine control and brake control based on SE', SE', SB, and SB'SB', and the right rear wheel IRR during traction control is
The characteristics of the driving wheel speed VKRR generally exhibit the wheel speed characteristics shown in FIG. 3, similarly to the left rear wheel IRL.

Note that when the friction coefficients of the road surfaces that the left rear wheel IRL and the right rear wheel IRR touch on are different, and the slip of one rear wheel IRL or IRR increases early, the above engine control will control the slip of the one wheel IRL or IRR. Rate S RL %5llR
are the target slip ratios SE, SE', S for engine control.
It starts when E' is reached. Further, the above brake control is configured as a so-called left and right independent control system, and when each of the rear wheels IRL and IRR reaches the target slip ratio 5BSSB' or SB' for brake control,
This is started for each of the rear wheels IRL and IRR that have reached the target slip ratio.

Next, a method of controlling slip control and engine control by the brake control unit UTR will be described with reference to flowcharts shown in FIGS. 6 to 9.

FIG. 6 is a flowchart showing the main control of traction control in the slip control unit (UTR);
FIG. 7 is a flowchart showing a control method for engine control in the slip control unit UTR, and
FIG. 8 is a flowchart showing a brake control method in the slip control unit (UTR). Also,
FIG. 9 is a flowchart showing a method for correcting the target slip ratio in the slip control unit (UTR).

Note that the symbol P in FIGS. 6 to 9 indicates a step.

Based on FIG. 6, the main control of slip control in the slip control unit 1-UTR will be explained.

Mass, throttle sensor 61, wheel speed sensor 62, wheel speed sensor 63, 64, 65, 66, accelerator opening sensor 67, motor rotation amount detection sensor 68, slip control mode selection switch 70, brake switch 71SG sensor 73, yaw rate sensor 74 detection results are respectively read (Pi).

Next, it is determined whether or not a failure has occurred in the slip control unit UTR (P2).
If there is no failure in the UTR, the wheel speed sensor 6
Each rear wheel IRL, IRR, that is, the respective drive wheel speed VKIL, VK- of each drive wheel detected based on the wheel speed signals from 3 to 66, and the front wheel IFL, IFR1, that is,
From the driven wheel speed VJ which is the average value of the wheel speed of each driven wheel, the respective slip rates SIL% SR of the rear wheels IRL and IRR are calculated.
R is calculated (P3), then the accelerator opening sensor 6
Based on the detection result of step 7, it is determined whether or not the accelerator opening is fully open (P4), and if the accelerator opening is not fully open, the actual slip rate of each drive wheel SRL%S
The slip JSsax, whichever is larger among RR, is compared with the basic target slip ratio SE for engine control.
If the slip ratio Saa, I is equal to or higher than the basic target slip ratio SE, a lower limit control value SM for the throttle opening is set (P6.7), and engine control is executed (P8).

In engine control, as shown in FIG. 7, when it is determined that the slip ratio increases and the slip ratio S,... has reached the target slip ratio SE for engine control (Pll),
The throttle opening degree Tn is set to the lower limit value SM, and 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. The throttle opening degree of the throttle valve 42 is reduced to the lower limit value SM (P
ll, 16).

In this way, once the opening degree of the throttle valve 42 is lowered to the lower limit value SM, the throttle opening degree Tn
is set as the throttle opening TH-M so that the slip ratios of the rear wheels IRL and lI'lR converge to the basic target slip ratio SE (PI3).

In addition, as shown in FIG. 8, the slip control unit UT
R sets the basic target slip rate SB for brake control while performing engine control (P9 (
Fig. 6), P21), even though the above engine control is being executed, the slip rate S of the rear wheels IRL and IRR is
IL% Sll increases and slip rate SRL% SI
When R reaches the basic target slip rate SB, the rear wheel IR
Brake 21RL, so that slip ratio 5ILN 5ti11 of L, IRR converges to basic target slip ratio SB,
Set the brake fluid pressure P neLs P n+u of 21RR, respectively (P22.23), and the brake fluid pressure P rl
Based on ts P n**, on-off valve 32.34.36L
, 36R, 37RL, and 37RR, the on-off valve 32 is switched to the fully open position, the on-off valve 34 is switched to the fully closed position, and the on-off valves 36L, 36R.

A flow control signal is output to the brakes 3711L and 37RR to adjust the brake fluid pressures in the brakes 21RL and 21RR to the brake fluid pressures PnRts Pni*, respectively (P24). By adjusting the brake fluid pressure, the slip ratios of the rear wheels IRL and IRR are reduced to 5IILSS and 1R.
decreases and the slip ratios SIL, SIl, and l respectively become below the basic target slip ratio SB, the rear wheel 111L
, IRRi: Brake control for P22 is about to end.
．． 25), Left and right rear wheels IRL, IR1? The brake fluid pressure is released, respectively.

Furthermore, as shown in FIG.
As described above, R corrects each of the target slip ratios SE and SB in step 5) based on the yaw rate and steering amount to the vehicle.

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 greater than the predetermined value α, and the detected steering amount θ is the predetermined value. When it is below β, each target slip rate SE.

The first target slip ratios SE' and SB' are respectively corrected by reducing SB to a predetermined ratio (a%, 100>a) (P42.43.44).

Further, when the detected yaw rate is less than the predetermined value α and the detected steering amount is more than the predetermined value β, each target slip rate SE, SB is set to a predetermined ratio (b%, 1
00>b>a), and the first target slip rate S
Correct to the second target slip ratio SE'SB' which is set larger than E' and SB' (P42.43.4
5).

Note that when the yaw rate is less than the predetermined value α, the vehicle A is substantially traveling straight, so the brake control unit UTR adjusts each target slip ratio SE without correcting each target slip ratio SE, SB.

The engine control and brake control described above are performed based on the SB (P42.46).

In addition, in the main control, slip control 22-bit UT
A malfunction or abnormality in the slip control unit UTR is detected by recognition of an abnormality in the storage means built into 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 readout. When this happens, the slip control is stopped, the brake fluid pressure increased by the brake control is released, and the motor 1 is
06 is held in the reverse position, the throttle opening depending on the accelerator opening is ensured, and a failure signal is issued to the driver by a warning lamp or a warning buzzer. (P 10.11) Also, the main control ends when the accelerator pedal 43 is released and the accelerator opening is fully closed (PI3).

As described above, in the above embodiment, the brake control unit (UTR) sets the slip rates of the rear wheels IRL and IRR to the basic target slip rate SE when the slip rates of the rear wheels IRL and IRR reach the basic target slip rates SE and SB.

The drive torque transmitted to the rear wheels IRL, IRR is regulated so as to converge to SB, and the basic target slip ratios SE, SB are corrected based on the detection results of the yaw rate sensor 74 and the steering angle sensor 69. , these basic target slip rates are reduced. Therefore, the slip roughness of the driving wheels IRL and IRR when the vehicle A turns is suppressed to a greater extent than when the vehicle A is traveling straight, so that the stability of the vehicle when the vehicle A turns is improved.

Further, the brake control unit UTR detects a yaw rate equal to or higher than a predetermined value by the yaw rate sensor 74,
When the steering angle sensor 69 detects a steering amount equal to or less than a predetermined value, the basic target slip ratio SESSB is corrected to the first target slip ratio SE', SB', and
When a yaw rate less than a predetermined value is detected and a steering amount exceeding a predetermined value is detected, the basic target slip ratio SE
.

SB is corrected to a second target slip ratio SE'SB' that is set larger than the first target slip ratio SE', SB'. Therefore, when vehicle A is in a relatively unstable state with turning performance greater than that corresponding to the driver's steering, the slip of the rear wheels IRL and IRR is greatly suppressed, and the vehicle Stability is ensured, and when vehicle A is about to make a large turn in a relatively stable state due to steering by the driver, slip is not excessively suppressed, that is, the running performance of the vehicle is impaired. (to ensure the stability of the vehicle).

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and it goes without saying that various changes can be made within the scope of the claims. Nor.

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

Furthermore, although the slip control unit (UTR) is equipped with an ABS control means, the present invention is not limited thereto.

However, it is also applicable to slip control lids for vehicles that are not equipped with ABS.

Furthermore, in the above embodiments, the engine control is performed by controlling the throttle opening and reducing the engine output, but the present invention provides variable control of the engine ignition timing and/or engine control. It can also be applied to a slip control device that controls the engine to reduce engine output by cutting fuel, or a slip control device that uses both of these engine control methods and an engine control method that controls the throttle opening. It is.

Furthermore, the throttle opening may be controlled by a step motor that opens and closes the throttle valve instead of the throttle opening adjusting mechanism.

(Effect of the invention) The present invention achieves the following effects with the above configuration.

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

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

[Brief explanation of drawings]

FIG. 1 is a schematic overall configuration diagram of a vehicle equipped with a vehicle slip control device according to an embodiment of the present invention. FIGS. 2A, 2B, 2C, and 2D are explanatory diagrams showing the cross-sectional structure and operation of the throttle opening adjustment mechanism shown in FIG. 1. FIG. 3: This is a diagram showing, as a time chart, the relationship between the general wheel speed characteristics of the rear wheels during traction control and the engine control and brake control by the traction control means. Figure 4 shows how to set both target slip rates for the rear wheels.
FIG. 2 is an explanatory diagram showing in a block diagram a circuit for determining a target slip value for brake control and a target slip value for engine control. FIG. 5 is a diagram showing the characteristics of the throttle opening lower limit control value for engine control set by the traction control means. FIG. 6 is a flowchart showing the main control of traction control in the brake control unit in FIG. 1. FIG. 7 is a flowchart showing a method of controlling the engine in the slip control unit. FIG. 8 is a flowchart showing a control method for brake control in the slip control unit. FIG. 9 is a flowchart showing a method for correcting the target slip ratio in the slip control unit. IFL, IFRlIRL, IRR 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, 21PR, 21RL, 21RR brake, 22F, 22FR122RL, 22RR caliper,
23FL, 23FR, 23RL, 23RR, 33-
Brake piping, 25-brake pedal, 260 booster, 27 mask cylinder, 28 hydraulic supply pipe, 28a branch pipe, 29 return piping, 31 reservoir tank, 32.34.36L, 3
6R, 371'L, 37FR137RL, 37RR on-off valve, 38FL, 38FR, 38RL, 38RR relief pipe, 41 Intake passage, 42 Throttle valve, 43
accelerator pedal, 44 throttle opening adjustment mechanism, 61 throttle sensor, 62 vehicle speed sensor, 63.6
4.65.66 Wheel speed sensor, 6T Accelerator opening detection sensor, 68 Motor rotation amount detection sensor, 69 Rudder 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 merging section, SE basic target slip ratio for engine control, SB
Basic target slip rate for brake control. Figure 3 l t2 3 Time Figure 5 Figure A Figure 8

Claims (2)

[Claims] (1) Slip detection means for detecting the slip rate of the drive wheels, and a slip detection means for detecting the slip rate of the drive wheels so that the slip rate of the drive wheels converges to at least the target slip rate when the slip rate reaches a predetermined target slip rate. A 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 steering angle detection means for detecting the amount of steering of the vehicle. and a detection means, the slip suppression means comprising a correction means for reducing the target slip ratio when a turning state of the vehicle is detected based on the detection results of the yaw rate detection means and the steering angle detection means. A slip control device for a vehicle, characterized in that: (2) When the yaw rate detecting means detects a yaw rate equal to or higher than a predetermined value, and the steering angle detecting means detects a steering amount equal to or less than a predetermined value, the correcting means adjusts the target slip ratio by a first correction. When the yaw rate detecting means detects a yaw rate equal to or higher than a predetermined value and the steering angle detecting means detects a steering amount exceeding a predetermined value, the correcting means adjusts the target slip ratio to The second correction amount is set smaller than the first correction amount.
2. The vehicle slip control device according to claim 1, wherein the vehicle slip control device reduces the amount by a correction amount of .