JP3112322B2 - Vehicle slip control device - Google Patents

Abstract

PURPOSE:To surely perform take-off without deterioration of acceleration by changing control content of slip control into the reducing direction giving torque to drive wheels, when motion of a vehicle in the opposite direction to the rotating direction of drive wheels is detected during slip control. CONSTITUTION:The respective detected signals from respective wheel speed sensors S1-S4, an accelerator switch S5, respective brake switch S6, S7, and a slope climbing sensor S8 consisting of an inclination meter and the like, are respectively input to a control unit U. Meanwhile, the control unit U outputs respective control signals to fluid pressure adjusting valves 15R, 15L for front wheels namely drive wheels, opening/closing valves 16R, 16L for rear wheels, a three-way electromagnetic changeover valve 38, and a torque adjusting means 9 for an engine. In this case, the control unit U detects the motion of a vehicle in the opposite direction to the rotating direction of the drive wheels. When he motion of the vehicle in the opposite direction is detected during slip control, the control content of slip control is changed in the direction of reducing giving torque to the drive wheels.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slip control device for a vehicle, which prevents a drive wheel from slipping too much on a road surface.

[0002]

2. Description of the Related Art Various slip control devices (traction control devices) have been proposed which prevent the driving wheels from slipping on the road surface during acceleration of the vehicle or the like, thereby satisfying acceleration performance and vehicle stability. ing.

[0003] The slip control is performed by reducing the torque applied to the driving wheels. Therefore, the braking control for applying a braking force to the driving wheels and the engine for reducing the generated torque (output) of the engine are performed. Control is performed. It has been proposed that the slip control be performed by both the brake control and the engine control, and also that the slip control be performed only by the brake control or only by the engine control. And
In both the brake control and the engine control, feedback control is generally performed so that the actual slip value of the drive wheels with respect to the road surface becomes a predetermined target value.

[0004] Excessive slipping of the drive wheels is particularly likely to occur when the vehicle starts, and Japanese Patent Laid-Open Publication No. 2-169357 discloses a system in which slip control is performed at the time of starting.

[0005]

Even if slip control is performed at the time of starting the vehicle, the vehicle may not start properly unless the torque applied to the drive wheels is appropriate. For example, in a situation where the vehicle is very slippery on an uphill road such as an ice burn, even if the slip control is performed, a situation in which the vehicle retreats instead of starting may occur. Also, particularly in a rear-wheel drive vehicle, the rear part of the vehicle body may exhibit a lateral movement behavior in which the rear part of the vehicle pretends to be hips, even if the vehicle does not retract.

Needless to say, appropriate slip control may be performed according to the road surface condition. However, it is very difficult to accurately estimate the road surface condition, particularly, the friction coefficient of the road surface. If the slip control was always performed assuming a situation in which the vehicle would reverse, the torque applied to the drive wheels would have been excessively reduced on a flat road or a road surface with a large friction coefficient. As a result, the acceleration at the time of starting is extremely deteriorated. This applies not only to the start in the forward direction but also to the start in the reverse direction.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a vehicle slip control device capable of starting more reliably without deteriorating acceleration at the time of starting.

[0008]

In order to achieve the above object, the present invention has a first configuration as follows. That is, as described in claim 1 of the claims, the slip control of the vehicle is configured such that the torque applied to the drive wheels is reduced to prevent the slip value of the drive wheels against the road surface from becoming excessive. In the device, a reverse operation detecting means for detecting the movement of the vehicle in the direction opposite to the rotation direction of the drive wheels,
During the slip control, when the vehicle movement in the direction opposite to the rotation direction of the drive wheel is not detected by the opposite operation detection means, the drive wheel is driven so that the actual slip value of the drive wheel becomes a predetermined target value. On the other hand, if the vehicle movement in the direction opposite to the rotation direction of the drive wheel is detected by the opposite operation detecting means during the slip control while the applied torque is changed, the actual slip value of the drive wheel is adjusted to the predetermined value. And control content changing means for changing the applied torque to the drive wheels so as to have a value smaller than the target value.

In order to achieve the above object, the present invention has a second configuration as follows. That is,
According to a second aspect of the present invention, there is provided a vehicle slip control device configured to prevent a slip value of a drive wheel from being increased with respect to a road surface by reducing an applied torque to the drive wheel. A steering angle detecting means for detecting that the steering angle is substantially zero, a lateral motion detecting means for detecting a lateral movement of the vehicle, and the steering angle is substantially reduced by the detecting means during the slip control. If at least one of 0 and the presence of lateral movement of the vehicle is not detected, the torque applied to the drive wheels is changed so that the actual slip value of the drive wheels becomes a predetermined target value. On the other hand, during the slip control, when the steering angle of the steering wheel is substantially zero and the lateral movement of the vehicle is detected by the detecting means, the actual slip value of the drive wheel is determined by the predetermined value. A configuration equipped with a control changing means for changing the applied torque to the drive wheels such that a value smaller than the value.

In the slip control, in which feedback control is performed on the applied torque to the drive wheels so that the actual slip value of the drive wheels becomes a predetermined target value, the control content changing means changes the target value. It can be configured to reduce.

[0011]

According to the present invention, when a situation occurs in which the vehicle does not start properly, that is, because the drive wheels are still slipping excessively with respect to the road surface, the vehicle rotates the drive wheels. When the vehicle moves in the opposite direction to the direction or when the vehicle body moves in the lateral direction even though the steering wheel is almost straight, the torque applied to the drive wheels is further reduced, and the vehicle can be reliably started. Further, since the applied torque to the drive wheels is not usually reduced too much, no problem arises in securing the acceleration at the start. Preferred aspects of the invention and its advantages will be apparent from the description of the following examples.

[0012]

1 is a front left wheel, 1FR is a front right wheel, 1RL is a rear left wheel, and 1RR is a rear right wheel. The engine 2 is mounted horizontally on the front of the vehicle body, and the torque generated by the engine 2 is transmitted to the clutch 3, the transmission 4, and the differential gear 5, and then transmitted to the left front wheel via the left drive shaft 6L. 1FL and to the right front wheel 1FR via the right drive shaft 6R. As described above, the vehicle has the front wheels 1F
L, 1FR are drive wheels, and rear wheels 1RL, 1RR are front wheel drive vehicles that are driven wheels.

[0013] Brakes 7FR to 7R mounted on each wheel
R is a hydraulic disk brake.
Further, a master cylinder 8 as a brake hydraulic pressure generating source is provided.
Is a tandem type having two discharge ports 8a and 8b. A brake pipe 13 extending from one discharge port 8a of the master cylinder 8 is branched into two on the way.
The branch pipe 13F is connected to the left front wheel brake 7FL (a wheel cylinder mounted in the caliper), and the branch pipe 13R is connected to the right rear wheel brake 7RR.
The branch pipe 14 extending from the other discharge port 8b of the master cylinder 8 is also branched into two, the branch pipe 14F is connected to the right front wheel brake 7FR, and the branch pipe 14R is connected to the left rear wheel brake 7RL. It is connected.

Branch pipe 13 for front wheels, that is, for drive wheels
F and 14F are provided with an electromagnetic hydraulic pressure control valve 15L or 1F.
5R is connected, and an electromagnetic on-off valve 16L or 16R is connected to the branch pipes 13R and 14R for the rear wheels. The hydraulic pressure adjusting valves 15L and 15R are provided with a brake 7FL,
The brake fluid pressure supply from the master cylinder 8 to the 7FR and the brake fluid pressure of the brakes 7FL and 7FR
The mode of release to the reservoir tanks 22L and 22R via 1L and 21R is switched. The brake fluid in the reservoir tank 21L is returned to the pipe 13 via a pipe 25L to which a check valve 24L is connected by a pump 23L. Similarly, the brake fluid in the reservoir tank 22R is
By R, it is returned to the pipe 14 via the pipe 25R to which the check valve 24R is connected.

The stepping force on the brake pedal 12 is
The power is transmitted to the master cylinder 8 via a booster, that is, a brake booster 11. The booster 11 is basically the same as a known vacuum booster. However, in the case of slip control, as will be described later, the booster action is performed even if the brake pedal is not depressed. Is performed.

The booster 11 has a case 31 fixed to the vehicle body and the master cylinder 8, and the inside of the case 31 is formed by a diaphragm 32 and a valve body 33 fixed thereto. A chamber 34 and a second chamber 35 are defined. A negative pressure (for example, the negative pressure of the intake air of the engine 2) is always supplied to the first chamber 34. When the brake pedal is not depressed, the second chamber 35 is communicated with the first chamber 34, -The operation of the star 11 is stopped. When the brake pedal 12 is depressed,
The communication between the two chambers 34 and 35 is interrupted and the second chamber 35
The diaphragm 32 is displaced forward together with the valve body 33 to perform the boosting function.

The switching between the negative pressure supply and the atmospheric pressure supply to the second chamber 35 is basically performed by a valve device provided in the valve body 33. This valve body 33
The portion will be described with reference to FIG.

First, the valve body 33 has a power piston 41 fixed to the diaphragm 32. In a recess 41a formed in the power piston 41, a reaction disk 42 and a base end of an output shaft 43 are provided. Are fitted. This output shaft 43 serves as an input shaft of the master cylinder 8. A valve plunger 45 is mounted in the valve body 33 at the tip of the input shaft 44 connected to the brake pedal 12. Behind the valve plunger 45, a vacuum valve 46 is provided.

The power piston 41 has a pressure introducing passage 50.
The pressure introducing passage 50 is always in communication with a space X formed around the valve plunger 45. This space X is always in communication with the second chamber 35. A valve seat 47 on which the vacuum valve 46 is detached and seated is formed at an opening end of the pressure introducing passage 50 on the space X side. Further, the vacuum valve 46 includes a valve plunger 45.
The seat is also detached from and seated on a valve seat 45a formed at the rear end.

In the above configuration, it is assumed that a negative pressure is introduced into the pressure introducing passage 50. In this state, when the brake pedal 12 is not depressed, the vacuum valve 46 is seated on the valve seat 45a by the urging force of the springs 48 and 49 in the state of FIG. ing. Therefore, the pressure introduction passage 5
The negative pressure from 0 is introduced into the second chamber 35 via the space X, and no boosting action is performed.

When the brake pedal 12 is depressed,
The input shaft 44 and thus the valve plunger 45 are moved forward (to the left in the drawing). During this forward movement, the vacuum valve 46
Is first seated on the valve seat 47 and the space X and the pressure introduction passage 50 are
To the vacuum valve 46 and the valve seat 45
a are separated. When the vacuum valve 46 and the valve seat 45a are separated from each other, the atmospheric pressure from behind the valve body 33 is introduced into the space X, and the second chamber 35 becomes the atmospheric pressure. As a result, the diaphragm 32 is displaced forward together with the valve body 33, and as a result, the output shaft 43 moves forward and a boosting action is performed. The brake reaction force from the master cylinder 8 is transmitted via the reaction disk 42 to the valve plunger 45 and thus to the brake pedal 12.
When the brake pedal 12 is released, the return spring 36 (see FIG. 1) returns to the state shown in FIG. 2 to prepare for the next boosting action.

The above-described parts are the same as those of the known vacuum booster, but in this embodiment, the negative pressure of the first chamber 34 is introduced into the pressure introduction passage 50 for slip control. The state is switched to a state in which atmospheric pressure is introduced. That is, the first chamber 34 and the pressure introduction passage 5
0 is connected via a pipe 37, and a three-way electromagnetic switching valve 38 (see FIG. 1) is connected to the pipe 37. The switching valve 38 allows the pressure introduction passage 50 to communicate with the first chamber 34 during demagnetization, and introduces atmospheric pressure into the pressure introduction passage 50 during excitation. When the switching valve 38 is excited and atmospheric pressure is introduced into the pressure introducing passage 50, the space X and hence the second chamber 35
Thus, even if the brake pedal 12 is not depressed, the pressure becomes the atmospheric pressure. As a result, a boosting action is performed to generate a brake hydraulic pressure in the master cylinder 8.

FIG. 3 schematically shows a control system. In FIG. 3, U is a control unit constituted by using a microcomputer.
Signals from sensors or switches S1 to S7 are input. The sensors S1 to S4 detect rotation speeds of the wheels 1FL to 1RR. The switch S5 is an accelerator switch that is turned on when the accelerator pedal 10 is fully closed. Switches S6 and S7 are each
The switch is activated when the key pedal 12 is depressed, for example, one switch is normally open and the other is normally closed. The sensor S8 is configured using an inclinometer or the like, and is a sensor that detects that the vehicle is on an uphill road.

The output from the control unit U to each device shown in FIG. 3 is indicated by reference numeral 9 which is a torque adjusting means for adjusting the generated torque of the engine 2. The torque adjusting means 9 adjusts the intake air amount, for example,
Alternatively, the generated torque is adjusted by a combination of the number of fuel cut cylinders and the ignition timing adjustment.

Next, an outline of the slip control will be described. In the embodiment, the slip value of the drive wheel is set as “slip value = drive wheel speed−vehicle speed”, and the vehicle speed is the average value of the left and right driven wheel speeds. Is used.

Engine control First, the engine control starts with the left and right front wheels 1FL, 1FR.
Is set when the larger one of the slip values becomes equal to or greater than a predetermined start threshold value.
The engine control is performed so that the actual slip value is equal to the engine target value (first target value) STE.
Is controlled by feedback control. The engine control is stopped when the accelerator is fully closed.

Brake Control The brake control is started when all of the following conditions are satisfied. The first start condition is that the engine is being controlled. The second start condition is that the vehicle speed is a predetermined first vehicle speed V
1 or less.

For the purpose of this brake control, the switching valve 38 is excited at the same time as the start of the engine control, so that the booster 11 is brought into a boosted state and the hydraulic pressure regulating valves 15L, 15
R is at the relief position, and the on-off valves 16L and 16R are closed. Then, after a predetermined time has elapsed since the switching valve 38 was excited, the brake control is started.

The brake control is performed on the left and right driving wheels 1FL, 1F.
By independently controlling the hydraulic pressure regulating valves 15L and 15R in such a manner that the actual slip value of each of R becomes the brake target value (second target value) STB (> STE). (Duty control).

The suspension of the brake control is performed when any one of the following conditions is satisfied. The first stop condition is when engine control is stopped. The second stop condition is when the vehicle speed becomes higher than a predetermined second vehicle speed V2 (V2> V1). The third stop condition is that when the brake pedal 12 is depressed, the switch S
6 or S7 (when the switches S6 and S7 detect that the brake pedal 12 is being depressed, the start of the brake control is prohibited).

When the brake control is stopped, the switching valve 38 is operated as long as the engine control is performed, the hydraulic pressure adjusting valves 15L and 15R are in the relief positions, and the on-off valve 1
6L and 16R are closed (the same state as the standby state until the start of the brake control). When the engine control is stopped or the brake pedal 12 is depressed, the switching valve 38 is demagnetized.

Next, a control example of the present invention will be described with reference to a flowchart of FIG. 4, where P indicates a step in the following description. First, at P1, after a signal from each sensor or the like is input, at P2, it is determined whether or not the vehicle is currently on an uphill road (in the embodiment, a sloping front) by checking the output state of the sensor S8 . If the determination in P2 is YES, in P3, it is determined whether the vehicle is starting (starting in the forward direction in the embodiment). This determination of the start can be made, for example, by checking whether the vehicle speed is a low vehicle speed equal to or lower than a predetermined vehicle speed and the accelerator is open.

At P4, it is determined whether slip control is being performed in both the engine control and the brake control. If the determination in P4 is YES, in P5,
It is determined whether the vehicle is moving backward. This backward movement of the vehicle can be determined, for example, by looking at the rotation direction of the driven wheel. If the determination in P5 is YES, in P7, the brake target value STB is decreased. As a result, the applied torque to the drive wheels is further reduced by an amount corresponding to the decrease in STB.

After P7, it is determined in P8 whether the vehicle has been further retreated. If the determination in P8 is YES, it is determined that the applied torque to the drive wheels is still large, and the engine target value S is determined in P9.
The TE is reduced, and the torque applied to the drive wheels is further reduced by the reduction in STE. If the determination in P2 to P5 or P8 is NO, the control is returned as it is.

FIG. 5 shows another control example of the present invention. In FIG. 5, P11 to P14 correspond to P1 to P in FIG.
4, P17 is the same as P7 in FIG. 4, and P19 is the same as P9 in FIG. 4, so that the description of this part will be omitted. In FIG. 5, instead of P5 in FIG.
5, P16 is determined. That is, the steering angle of the steering wheel is almost 0 (the determination of P15 is YE
S), and when the yaw rate is occurring (when the determination in P16 is YES and the lateral movement of the vehicle body is detected),
At 17, the brake target value STB is decreased. Also, if there is any yaw rate despite the reduction of the brake target value STB (the determination in P18 is YES), the engine target value STE is determined in P9.
Is reduced. Although not shown, the control unit U receives a signal from a sensor or a switch for detecting that the steering angle is substantially zero, and also receives a signal from a yaw sensor.

Although the embodiment has been described above, the present invention is not limited to this, and includes, for example, the following case. The slip value of the drive wheel is not a difference between the drive wheel speed and the vehicle speed, but is, for example, “drive wheel speed /
Vehicle speed "or" (driving wheel speed-vehicle speed) / vehicle speed)], and the brake control is performed separately without using the booster 11, as is generally performed. A pump for generating brake hydraulic pressure may be used.

The slip control may be only the engine control or only the brake control. Of course, the control content changing means may lower the brake target value STB when only the brake control is performed, and may lower the engine target value STE when only the engine control is performed. When performing both the engine control and the brake control, both the engine target value STE and the brake target value STB can be simultaneously reduced. However, before the generated torque of the engine decreases (STE decreases), the brake target value S
By lowering TB, the torque generated by the engine is sufficiently ensured while reducing the torque applied to the drive wheels, which is preferable for starting. As a further reduction of the torque applied to the drive wheels by the control content changing means, the target value STB
Alternatively, an appropriate technique such as setting a control amount obtained by adding a predetermined ratio to the control amount set by the target value in addition to the reduction of the STE may be adopted.

The same can be applied to the case where the vehicle starts moving in the reverse direction. Whether the rotation direction of the drive wheels and the movement of the vehicle are the same or opposite can be determined by, for example, looking at the shift position of the transmission and the rotation direction of the driven wheels. P2
Although it is possible to eliminate the determination as to whether or not the vehicle is on an uphill road in FIG. 4 (FIG. 4) or P12 (FIG. 5), by adding this determination, the torque applied to the drive wheels is reduced unnecessarily due to noise or the like. This is preferable in order to more reliably prevent a situation in which the acceleration performance at the time of starting is deteriorated.

[0039]

[Brief description of the drawings]

FIG. 1 is an overall system diagram showing one embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a main part of the brake booster.

FIG. 3 is a diagram showing a control system of the present invention.

FIG. 4 is a flowchart showing a control example of the present invention.

FIG. 5 is a flowchart showing another control example of the present invention.
G.

[Explanation of symbols]

 1FR, 1FL: drive wheel 1RR, 1RL: driven wheel 2: engine 9: generated torque adjusting means 7FR to 7FL: brake 11: brake kicker 15R, 15L: brake hydraulic pressure adjusting means U: control unit S1 to S4: Wheel speed sensor

Continuation of the front page (56) References JP-A-1-224418 (JP, A) JP-A-64-85862 (JP, A) JP-A-64-32954 (JP, A) JP-A-63-222964 (JP) JP-A-2-169357 (JP, A) JP-A-58-16948 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B60T 8/58 F02D 29/02 311

Claims (6)

(57) [Claims] 1. A slip control device for a vehicle, wherein a torque applied to a drive wheel is reduced to prevent an excessive slip value of the drive wheel with respect to a road surface. and opposite movement detecting means for detecting a movement direction of the vehicle, during the slip control, the rotation direction of the driving wheels by the opposite movement detecting means detects the motion in the opposite direction of the vehicle Tei
If not, the actual slip value of the drive wheel is
While changing the torque applied to the drive wheels so that
During the lip control, the driving wheel is
When a vehicle movement in the direction opposite to the direction of rotation of the vehicle is detected
The actual slip value of the drive wheel is greater than the predetermined target value.
And a control content changing means for changing the applied torque to the drive wheels so that the value is also small . 2. A slip control device for a vehicle in which a torque applied to a drive wheel is reduced to prevent an excessive slip value of the drive wheel with respect to a road surface, wherein a steering angle of the steering wheel is substantially zero. and that the steering angle detection means for detecting a horizontal movement detecting means for detecting a motion in the lateral direction of the vehicles, during slip control, handle steering angle by the respective detecting means is substantially zero that The vehicle has lateral movement
If at least one of the
Drive so that the actual slip value of the wheel reaches the specified target value
While changing the applied torque to the wheels, during slip control,
Whether the steering angle is almost 0 by each of the detection means
When the lateral movement of one vehicle is detected, the actual
The slip value at this time becomes a value smaller than the predetermined target value.
And a control content changing means for changing the applied torque to the drive wheels in such a manner as described above. 3. The slip control according to claim 1, wherein the slip control is set so as to feedback control an applied torque to the drive wheels so that an actual slip value of the drive wheels becomes a predetermined target value. the control content changing means reduces the target value, the slip control apparatus for a vehicle, characterized in that. 4. The brake control according to claim 3, wherein the slip control includes controlling a braking force applied to the drive wheels such that an actual slip value of the drive wheels becomes a brake target value. the actual slip value of the driven wheel is performed by an engine control for controlling the generated torque of the engine so that the target value for the engine, the control content changing means, the blur - lowering the key for the target value, that A slip control device for a vehicle . 5. The control content changing means according to claim 4, wherein when the reverse detection means further detects retreat of the vehicle after the brake target value is reduced by the control content change means, Reducing the target value for the engine ,
Slip control device . 6. The control content changing means according to claim 3, wherein the slip control is performed only by engine control for controlling the generated torque of the engine such that the actual slip value of the drive wheel becomes the engine target value. but it lowers the target value for the engine, slip control system for a vehicle, characterized in that.