JP2588785B2 - Vehicle traction control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Object of the Invention (1) Industrial application field The present invention generates a braking force in a driving wheel brake device when an excessive slip tendency occurs in a driving wheel in a driving state. The present invention relates to a traction control method for a vehicle.

(2) Prior Art Conventionally, such a traction control method is known, for example, from US Pat. No. 389,353.

(3) Problems to be Solved by the Invention There are two types of the above-mentioned conventional ones, in which the control oil pressure of the left and right driving wheel brake devices is independently controlled when an excessive slip tendency occurs in the driving wheels in the driving state. It discloses that the control hydraulic pressure of the driving brake device is controlled collectively.

By the way, when traveling on a hill or a traveling road having a different coefficient of friction between the ground contact surface and both driving wheels, if the driving wheels tend to slip excessively, the control oil pressure of the driving wheel brake device is independently controlled in order to quickly recover the driving force. When the vehicle is running at a relatively high speed and the drive wheels tend to slip excessively, the stability of the vehicle is emphasized and the brake hydraulic pressure of the drive wheel brake device is controlled. Should be controlled collectively. However, if the braking hydraulic pressure is controlled in a fixed control mode as in the above-described conventional case, a satisfactory result cannot be obtained on both the driving force and the stability.

Therefore, the present applicant changes the control mode of the driving wheel brake device between when the driving force is important and when the vehicle stability is important, so as to improve the driving force and the stability while maintaining their harmony. A vehicle traction control method has already been proposed.

However, in the independent control mode, interference occurs between the drive wheels on which traction control is being performed and the engine mounted on the vehicle, and the target value of the drive wheel speed is set constant in the independent control mode and the collective control mode. In this case, a suppressing force for lowering the rotation speed acts on the vehicle-mounted engine from the driving wheel side. For example, when the traction control in the independent control mode is executed when the excessive slip tendency of one of the left and right drive wheels increases, the sum of the actual rotational speed of the vehicle mounted engine and the speeds of the left and right drive wheels is obtained. Almost 1/2 of
The difference from the ideal engine speed estimated from the above becomes large, the suppression force acting on the engine side from the drive wheel side becomes large, the engine speed drops unnecessarily, and control hunting occurs. There is a risk.

The present invention has been made in view of such circumstances,
Switching between the collective control mode and the independent control mode improves driving force and stability while maintaining harmony between them, and suppresses the suppression force acting on the engine mounted on the vehicle from the driving wheel side during traction control in the independent control mode. ,
It is an object of the present invention to provide a traction control method for a vehicle that avoids an unnecessary decrease in engine speed and a decrease in operation feeling.

B. Configuration of the Invention (1) Means for Solving the Problems The present invention provides an independent control mode for individually controlling the braking forces of a plurality of driving wheel brake devices, and a braking force of a plurality of driving wheel brake devices. It is possible to switch between a collective control mode and a collective control mode, wherein a target value of the drive wheel speed in the independent control mode is set to be larger than a target value of the drive wheel speed in the collective control mode.

(2) Operation According to the above feature, when the traction control is performed in the independent control mode, the driving force can be secured by the effect of limiting the differential between the driving wheels, and when the traction control is performed by the collective control, the stability is improved. The ideal engine that can be determined from each drive wheel speed at the time of traction control in the independent control mode by setting the target value of the independent control mode larger than the target value of the collective control mode The difference between the rotation speed and the actual engine rotation speed can be reduced.

(3) Embodiment Hereinafter, an embodiment in which the present invention is applied to a front engine / front drive vehicle will be described with reference to the drawings. First, in FIG. 1, the left front wheel and the right front wheel of the vehicle have left drive wheel brakes. device B _FL and right drive wheel brake device B _FR are mounted respectively, left driven wheel brake device B _RL and a right driven wheel brake device B _RR are respectively mounted to the left rear wheel and the right rear wheel. On the other hand, the brake pedal 1 is connected to a braking oil pressure generating means 3 capable of controlling and outputting the oil pressure from the oil pressure supply source 2 in accordance with the amount of depression of the brake pedal 1. The output oil pressure of the generating means 3 is applied to each of the brake devices B _FL , B _FL , B
_RL and B _RR . In addition, brake device B _FL for both drive wheels,
Inflow solenoid valves 4 _FL , 4 _FR and outflow solenoid valves 5 _FL , 5 _FR and brake devices B for both driven wheels provided corresponding to B _FR
Performing _RL, the inlet solenoid valve 4 _R and outlet solenoid valve 5 _R provided commonly to B _RR, the brake device _{B FL, B FR, B RL} , the holding or reduced to antilock control braking oil B _RR Also, the normally open solenoid valve 6 and the normally closed solenoid valve 7 for traction control and the inflow solenoid valves 4 _FL , 4 _FR and the outflow solenoid valves 5 _FL , 5 _{FR are} used to brake the two drive wheels.
B _FL, by controlling the braking oil B _FR can perform traction control.

The hydraulic supply source 2 includes a hydraulic pump P for pumping hydraulic oil from a reservoir R, an accumulator A connected to the hydraulic pump P, and a pressure switch S for controlling the operation of the hydraulic pump P.

The braking oil pressure generation means 3 has an input port 3a communicating with the oil pressure supply source 2, an output port 3b, and a release port 3c communicating with the reservoir R. The communication between the output port 3b and the input port 3a and the output port 3b By switching the communication between the release ports 3c according to the depression of the brake pedal 1,
Output port that outputs hydraulic pressure according to the amount of depression of brake pedal 1
It is configured to output from 3b.

On the other hand, each of the brake devices B _FL , B _FR , B _RL , and B _RR includes a cylinder body 8 and a brake piston 9 slidably fitted in the cylinder body 8, and the cylinder body 8 and the brake piston 9 is configured to exert a braking force by moving the braking piston 9 according to the hydraulic pressure acting on the braking hydraulic chamber 10 defined in 9.

Both the drive wheel brake device B _FL, the braking hydraulic pressure chambers 10 of the B _FR, inlet solenoid valves 4 _FL, 4 _FR and the outlet solenoid valve 5 _FL, 5 _FR are respectively connected in parallel, both driven wheel brake device B _RL , B
_An inflow solenoid valve _4R and an outflow solenoid valve _5R are connected in parallel to _RR . Thus, the inflow solenoid valves 4 _FL , 4 _FR , and 4 _R are solenoids
4 is a _FLS, 4 _FRS, 4 solenoid valve to shut off when the excitation of the _RS, also the outflow solenoid valve 5 _FL, 5 _FR, 5 _R is an electromagnetic valve which communicates at the excitation of the solenoid _{5 FLS, 5 FRS, 5 RS} . Moreover, the inflow solenoid valve 4 _FL , 4
_FR is interposed between the brake hydraulic chamber 10 and the oil passage 11 of the drive wheel brake devices B _FL and B _FR , and the outflow valve magnetic valves 5 _FL and 5 _FR are brake hydraulic pressures of the drive wheel brake devices B _FL and B _FR . Room 10 and reservoir R
The inflow solenoid valve 4 _R is interposed between the two driven wheel brake devices.
B _RL, is interposed between the output port 3b of the braking hydraulic pressure chambers 10 and the braking hydraulic pressure generating means 3 B _RR, outlet solenoid valve 5 _R both driven wheel brake device B _RL, braking hydraulic pressure chambers 10 and the reservoir of B _RR It is interposed between R.

The oil passage 11 and the output port 3b of the braking oil pressure generating means 3
A normally open solenoid valve 6 for traction control is interposed between them.
A normally closed solenoid valve 7 for traction control is interposed between the oil passage 11 and the hydraulic pressure source 2.

Solenoids 4 _FLS , 4 _FRS , 4 _RS , 5 _FLS , 5 _FRS , 5 _RS , 6 _S , 7 _S for each solenoid valve 4 _FL , 4 _FR , 4 _R , 5 _FL , 5 _FR , 5 _R , 6, 7 Excitation and demagnetization are controlled by the control means 12, and in a normal state, each solenoid 4 _FLS , 4 _FRS , 4 _RS , 5 _FLS , 5 _FRS , 5 _RS ,
6 _S and 7 _S are in a demagnetized state. Thus, in the anti-lock brake control at the time of the braking operation, the inflow solenoid valves 4 _FL , 4 _FR , 4 _R corresponding to the wheels that are about to be locked are shut off, whereby the wheels are locked. To avoid this, the increase in braking force is suppressed, but if the wheels are still about to enter the locked state, the corresponding outflow solenoid valve 5
_{When the FL} , _5FR , and _5R are in the communicating state, the braking force is reduced, and the tendency to lock the wheels can be eliminated.

When the drive wheels are about to slip excessively,
When the solenoids 6 _S and 7 _{S of the} traction control normally-open solenoid valve 6 and the normally-closed solenoid valve 7 are excited, the oil pressure from the oil pressure supply source 2 acts on the oil passage 11. When the braking force is increased, the solenoids 4 _FLS , 4 _FRS , 5 _FLS , and 5 _FRS are kept demagnetized, and the hydraulic pressure in the oil passage 11 is increased by the brake device for each drive wheel.
The brake hydraulic pressure in the brake hydraulic chamber 10 is caused to act on the brake hydraulic chambers 10 of B _FL and B _FR respectively, and when the braking force is to be maintained, the solenoids 4 _FLS and 4 _FRS are excited and the solenoids 5 _FLS and 5 _FRS are kept demagnetized. When the braking force is further reduced, the 4 _FLS , 4 _FRS , 5 _FLS , and 5 _FRS are excited to release the hydraulic pressure in the brake hydraulic chamber 10. In such traction control, the control means 12 switches between the independent control mode and the collective control mode and executes the control. The configuration of the main part of the control means 12 for that purpose will be described below.

In Figure 2, the control means 12, inlet solenoid valves 4 _FL and outlet solenoid valve 5 _FL corresponding to the brake device B _FL for the left driving wheel
Solenoids 4 for the left drive wheel connected to the solenoids 4 _FLS and 5 _FLS , and the solenoid 4 for the inflow solenoid valve 4 _FR and the outflow solenoid valve 5 _FR corresponding to the right drive wheel brake device B _FR
FRS , 5 Solenoid control circuit for right drive wheel connected to _FRS 16
And an OR circuit 17 in which both solenoid control circuits 15 and 16 are connected in parallel to the input terminals and the output terminals are connected to the solenoids 6 _S and 7 _S of the normally open solenoid valve 6 and the normally closed solenoid valve 7.
And an averaging circuit 1 for averaging the left and right driving wheel speeds V _FL , V _FR
A first changeover switch 19 for selectively outputting the average drive wheel speed V _FA and the left drive wheel speed V _FL averaged by the averaging circuit 18 in accordance with the control mode; A second changeover switch 20 for selectively switching and outputting the average driving wheel speed _VFA and the right driving wheel speed _VFR averaged by the conversion circuit 18 in accordance with the control mode, and a left and right driven wheel speed V
_RL, a high select circuit 21 for selecting the higher of the V _RR as vehicle speed V _R, sets the driving wheel target speed for the collective control mode based on the vehicle speed V _R obtained in the high select circuit 21 a collective control target speed setting circuit 22, an independent control target speed setting circuit 23 for setting a driving wheel target speed for the independent control mode based on the vehicle speed V _R, sets both the target speed setting circuit 23 and 24 Third and fourth changeover switches 24 and 25 for selectively switching and outputting one of the set target speeds according to the control mode, and determining whether to select the independent control mode or the collective control mode. Mode determination circuit 26 for increasing and decreasing the target speed output from third and fourth changeover switches 24 and 25 when switching between the independent control mode and the collective control mode, gradually increasing / decreasing circuits 27 and 28 And the first switch A comparison circuit 29, 30 for inputting a comparison result between the drive wheel speed output from the switch 19 and a target speed from the gradually increasing / decreasing circuits 27, 28 to the left drive wheel solenoid control circuit 15, and a second changeover switch 20 And comparison circuits 31 and 32 for inputting the result of comparison between the drive wheel speed output from the controller and the target speed from the gradually increasing / decreasing circuits 27 and 28 to the right drive wheel solenoid control circuit 16.

Drive wheel speed detection sensors for left and right front wheels as drive wheels
S _FL, S _FR are mounted, the sensors S _FL, S _FR obtained in the driving wheel speed V _FL, V _FR filter 33 of the control unit 12
Respectively. In addition, driven wheel speed detection sensors S _RL and S _RR are mounted on the left and right rear wheels as driven wheels,
The driven wheel speeds V _RL , V _RR obtained by the sensors S _RL , S _RR are input to the filters 35, 36 of the control means 12, respectively.

The filters 33 and 34 are connected to an averaging circuit 18. The averaging circuit 18 performs an averaging operation of the driving wheel speeds V _FL and V _FR after removing the noise by the filters 33 and 34, that is, ｛V
_{An operation of FA} = ( _VFL + _VFR ) / 2｝ is performed. By this calculation, the average driving wheel speed _VFA is output from the averaging circuit 18.

The first changeover switch 19 includes an individual contact 19a connected to the averaging circuit 18 and an individual contact 19b connected to the filter 33.
And the conduction state with the common contact 19c is determined by the control mode determination circuit 26.
Control mode judgment circuit
When the output of 26 is at a low level, conduction is established between the individual contact 19a and the common contact 19c, and the control mode determination circuit 26
Becomes high level, the connection between the individual contact 19b and the common contact 19c is conducted. The second changeover switch 20 switches the conduction state between the individual contact 20a connected to the averaging circuit 18 and the individual contact 20b connected to the filter 34, and the common contact 20c by the output of the control mode determination circuit 26. Yes, when the output of the control mode determination circuit 26 is at a low level, conduction between the individual contact 20a and the common contact 20c is conducted. When the output of the control mode determination circuit 26 is at a high level, conduction between the individual contact 20b and the common contact 20c is conducted. I do.

The driven wheel speeds V _RL , V from which noise has been removed by the filters 35 and 36
_RR is input to the high select circuit 21. Thus, the high select circuit 21 selects the higher one of the driven wheel speeds V _RL and V _RR and outputs it as the vehicle speed V _R.

The collective control target speed setting circuit 22 sets the target speed of the drive wheels when the collective control mode is selected to a high select circuit 21.
Are those set based on the vehicle speed V _R which is input from the high-speed side target velocity arithmetic circuit 22 _H for calculating a high-speed-side target velocity V _RHC based on vehicle speed V _R, the high-speed side target velocity V _RHC
And a low-speed side target velocity arithmetic circuit 22 _L for calculating a low-speed target speed V _RLC based on.

In Thus fast side target velocity arithmetic circuit 22 _H, the high-speed side target velocity V _RHC (km / h) is calculated for example according to the following equation (1).

_{V RHC = (17/16) × V} R +10.5 ...... (1) or low speed side in the target velocity arithmetic circuit 22 _L, for example, the following first (2) low-speed target speed V _RLC according formula (miles / h) Is calculated.

V _RLC = V _RHC -3 (2) The target speed setting circuit for independent control 23 sets the target speed of the drive wheels when the independent control mode is selected to the high select circuit 21.
Are those set based on the vehicle speed V _R which is input from the high-speed side target velocity arithmetic circuit 23 _H for calculating a high-speed-side target velocity V _RHI based on vehicle speed V _R, the high-speed side target velocity V _RHI
And a low-speed side target velocity arithmetic circuit 23 _L for calculating a low-speed target speed V _RLI based on.

In Thus fast side target velocity arithmetic circuit 23 _H, the high-speed side target velocity V _RHI (km / h) is calculated for example according to the following first equation (3).

_{V RHI = (17/16) × V} R +15.5 ...... (3) also in the low-speed side target velocity arithmetic circuit 23 _L, for example next (4) low-speed target speed V _RLI according formula (miles / h) Is calculated.

V _RLI = V _RHI −4 (4) The target speeds set by the collective control target speed setting circuit 22 and the independent control target speed setting circuit 23 are shown in FIG. That fast-side target velocity V _RHI to be used in the independent control mode is d _H only set larger than the high-speed-side target velocity V _RHC to be used in batch control mode and low-speed target speed V to be used in the independent control mode _RLI is intended to be set large only d _L than the low-speed-side target velocity V _RLC should be used in batch control mode, according to the above equation (1), second (4), the d _H is 5k
m / h and d _L are 4 km / h.

The third changeover switch 24 is a target speed setting circuit for collective control.
22 high-speed side target velocity arithmetic circuit 22 individual contacts are connected in _H 2 of
4a and the control and the individual contact 24b connected to the high speed side target velocity arithmetic circuit 23 _H independent control target speed setting circuit 23, electrical continuity between the common contact 24c connected to the gradual increase and reduction circuit 27 mode decision circuit 26 When the output of the control mode determination circuit 26 is at a low level, conduction is established between the individual contact 24a and the common contact 24c, and when the output of the control mode determination circuit 26 is at a high level, the individual contact 24b and the common Conduction is established between the contacts 24c. In addition, the fourth changeover switch 25
It is low speed side target velocity arithmetic circuit 22 the low speed side target velocity connected thereto individual contacts to the arithmetic circuit 23 _L of the individual is connected to the _L contact 25a and independently controlling target speed setting circuit 23 of the collective control target speed setting circuit 22 The conduction state between 25b and the common contact 25c connected to the gradual increase / decrease circuit 28 is switched by the output of the control mode determination circuit 26.When the output of the control mode determination circuit 26 is at a low level, the individual contacts 25a and When the common contact 25c conducts and the output of the control mode determination circuit 26 goes high, the individual contact 25b and the common contact 25c conduct.

The control mode determination circuit 26 receives the drive wheel speeds V _FL and V _FR from which noise has been removed by the filters 33 and 34, and the vehicle speed V _R from the high select circuit 21. Thus, the control mode determination circuit 26 determines, based on, for example, the deviation of the driving wheel speeds V _FL , V _FR and the vehicle speed V _R , whether to emphasize the driving force and to emphasize the vehicle stability, Thus, when it is determined that the independent control mode should be selected, a high-level signal is output, and when it is determined that the collective control mode should be selected, a low-level signal is output.

Therefore, in the collective control mode, the average driving wheel speed V _FA is obtained from the common contact 19c of the first changeover switch 19,
From the common contact 20c of the second changeover switch 20, the average driving wheel speed _VFA is obtained. From the common contact 24c of the third changeover switch 24, the high-speed target speed _VRHC for the collective control mode is obtained. The low-speed target speed _VRLC for the collective control mode is output from the contact 25c. Also, when an independent control mode, the left driving wheel speed V _FL from common contact 19c of the first changeover switch 19, the right driving wheel speed V _FR from the common contact 20c of the second changeover switch 20, a third changeover switch High-speed target speed V for independent control mode from 24 common contacts 24c
_RHI outputs the low-speed target speed V _RLI for the independent control mode from the common contact 25c of the fourth changeover switch 25, respectively.

The gradual increase / decrease circuits 27 and 28 are provided with the third and fourth changeover switches 2
The target speed input from 4, 25 is gradually increased or decreased when switching between the collective control mode and the independent control mode. That is, as shown in FIG. 4, when switching from the collective control mode to the independent control mode, that is, the signal input from the control mode determination circuit 26 to the gradually increasing / decreasing circuits 27 and 28 is switched from low level to high level. sometimes, increasing and reduction circuit 27 to the high-speed side target velocity stepwise increased from V _RHC to V _RHI, increasing and reduction circuit 28 stepwise increases the slow side target velocity from V _RLC to V _RLI. When switching from the independent control mode to the collective control mode, that is, when the output signal of the control mode 26 switches from the high level to the low level, the gradually increasing / decreasing circuit 27 steps the high-speed target speed from V _RHI to V _RHC . The gradually increasing / decreasing circuit 28 gradually decreases the low-speed target speed from V _RLI to V _RLC .

The non-inverting input terminal of the comparison circuit 29 has a first switch 19
Is connected to the inverting input terminal, a gradual increase / decrease circuit 27 is connected, and the output terminal is connected to the left drive wheel solenoid control circuit 15. Therefore, the comparison circuit 29 determines that the drive wheel speed input from the common contact 19c gradually increases / decreases.
A high-level signal is input to the left drive wheel solenoid control circuit 15 when the high speed target speed input from 7 is exceeded.

The common contact 19c is connected to the inverting input terminal of the comparing circuit 30, the increasing / decreasing circuit 28 is connected to the non-inverting input terminal, and the output terminal is connected to the left drive wheel solenoid control circuit 15. Therefore, the comparison circuit 30 inputs a high-level signal to the left driving wheel solenoid control circuit 15 when the driving wheel speed input from the common contact 19c is equal to or lower than the low-speed target speed input from the gradually increasing / decreasing circuit 28. I do.

The comparison circuits 31 and 32 correspond to the comparison circuits 29 and 30, respectively.The comparison circuit 31 is configured such that the driving wheel speed input from the common contact 20c is the high-speed target speed input from the gradually increasing / decreasing circuit 27. When it exceeds, a high-level signal is input to the right drive wheel solenoid control circuit 16, and the comparison circuit 32
Drive wheel speed input from common contact 20c gradually increases / decreases circuit 2
A high-level signal is input to the right drive wheel solenoid control circuit 16 when the speed is equal to or lower than the low speed target speed input from 8.

The left drive wheel solenoid control circuit 15 and the right drive wheel solenoid control circuit 16 have corresponding comparison circuits 29, 30; 31, 32
The left driving wheel speed and the right driving wheel speed are set to the high-speed target speeds V _RHC and V _RHI and the low-speed target speed V based on the input signals from
Each solenoid 4 _FLS , 4 to fit between _RLC , V _RLI
FRS , 5 _FLS , 5 _FRS , 6 _S , Outputs a signal for controlling the excitation and demagnetization of 7 _S.

According to such a configuration of the control means 12, when the driving force should be emphasized, the independent control mode in which the braking hydraulic pressure of the left driving wheel brake device _BFL and the right driving wheel brake device _BFR is independently controlled, and Left when stability is important
Solenoids 4 _FLS , 4 _FRS , 5 _FLS , 5 in the collective control mode that controls the braking hydraulic pressure of the right drive wheel brake devices B _FL , B _FR collectively
_FRS, 6 _S, 7 excitation-demagnetization control of _S is performed. That is, when the independent control mode, high-speed-side target velocity V _RHI and low-side target velocity V for independent control mode and the left driving wheel speed V _FL
The result of comparison with _RLI is input to the left drive wheel solenoid control circuit 15 from the comparison circuits 29 and 30, respectively, and the right drive wheel speed V _FR and the high speed target speed V _RHI and the low speed target speed for the independent control mode are set. The result of comparison with V _RLI is input from the comparison circuit 30 to the solenoid control circuit 16 for the right driving wheel. Thus the left drive wheel solenoid control circuit 15 outputs a control signal for the solenoid _{4 FLS, 5 FLS, 6 S} , 7 S to determine the slip tendencies of the left drive wheel based on the left driving wheel speed V _FL, also right drive The wheel solenoid control circuit 16 has the right drive wheel speed V _FR
And determines the tendency of the right drive wheel to slip based on the
Outputs control signals of 4 _FRS , 5 _FRS , 6 _S , 7 _S. In the collective control mode, the comparison result between the average driving wheel speed V _FA obtained by the averaging circuit 18 and the high-speed target speed V _RHC and the low-speed target speed V _RLC for the collective control mode is a left and right drive. is inputted to the wheel solenoid control circuits 15 and 16, both solenoid control circuit 15, 16 determines a slip tendency of the driven wheels based on the same driving wheel speed V _FA solenoid _{4 FLS, 4 FRS, 5 FLS} , 5 FRS ,
6 _S and 7 _S control signals are output.

Next, the operation of this embodiment will be described. When starting the vehicle on a road surface having a different friction coefficient on a slope or a ground road surface of the left and right driving wheels, the driving force should be more important than the stability of the vehicle. The slip tendency of the wheels is individually determined, and the braking pressure of the drive wheel on the side where the slip tendency is increased is independently increased. Thus the left when the slip tendency of one of the driving wheels is increased, the right drive wheel brake devices B _FL, along with one of the brake oil pressure increases to increase the braking force of B _FR, braking in the other drive wheel An increase in power is avoided, and a driving force can be ensured by a differential limiting effect between the left and right driving wheels.

Also at the time of high speed running, and the like should be emphasized vehicle stability than the driving force, in this case, left and right drive wheel brake devices B _FL, braking oil B _FR are collectively controlled. That is, the left, it is determined that excessive slipping tendency of the two drive wheels on the basis of the average value V _FA of the right driven wheel speed, the determination result both drive wheel brake device in accordance with the B _FL, the braking oil B _FR are controlled You. Therefore, it is possible to prevent a vehicle body vibration accompanied by a yaw change due to a torque fluctuation applied to the drive wheels occurring independently of left and right, thereby preventing the driver from feeling uncomfortable.

In this way, when the driving force is emphasized, the independent control mode,
When stability is emphasized, switching to the collective control mode is switched.In the independent control mode, excessive slip of the drive wheels is suppressed with high sensitivity to secure the driving force, and in the collective control mode, braking that leads to the occurrence of body vibration Oil pressure control can be dispensed with.

Moreover, the target speed of the drive wheels in the independent control mode
Since V _RHI and V _RLI are set higher than the target speeds V _RHC and V _RLC of the drive wheels in the collective control mode, the speed of the drive wheels being controlled during the traction control in the independent control mode is relatively high. Controlled to a large value. Therefore, the difference between the ideal engine speed determined from the drive wheel speed and the actual engine speed can be reduced, and the restraining force acting from the drive wheel side to the engine side can be reduced. It is possible to avoid as much as possible or control hunting to reduce the operation feeling.

When switching between the collective control mode and the independent control mode, the target speeds V _RHC , V _RLC ; V _RHI , V _RLI of the drive wheels are gradually increased or decreased, so that the operation at the time of switching can be performed smoothly. .

In the above embodiment, the traction control using only the braking force control has been described. However, the present invention is also applicable to the traction control using the engine output reduction control and the braking force control in combination. In this case, the traction control based on the reduction of the engine output is a collective control, and is set to be smaller than the target speeds V _RHC and V _RLC of the driving wheels in the collective control mode in the target value braking force control of the driving wheel speed. Then, interference between the engine output reduction control and the braking force control can be avoided, and the lack of traction due to the reduction in engine output can be compensated for by the braking force control in the collective control mode. Moreover a target value when the independent control mode brake force control, if you set larger than {V _R + (engine output reduction control target value -V _R) × 2}, when the traction control by the independent control mode The shortage caused by the engine output reduction control can be compensated for by the braking force control.

By the way, in determining whether to select the collective control mode or the independent control mode, the independent control mode is selected when the steering angle is equal to or less than a predetermined value, and the collective control mode is selected when the steering angle exceeds the predetermined value. The independent control mode may be selected when the lateral acceleration of the vehicle body is equal to or less than a predetermined value, and the collective control mode may be selected when the lateral acceleration of the vehicle body exceeds a predetermined value. May be set to an independent control mode when is less than a predetermined value, and a collective control mode may be selected when the yaw rate of the vehicle body exceeds a predetermined value.

C. Effects of the Invention As described above, according to the present invention, an independent control mode for individually controlling the braking forces of a plurality of drive wheel brake devices and a collective control for collectively controlling the brake forces of a plurality of drive wheel brake devices are provided. Since the control mode can be switched, traction control that is satisfactory in terms of both securing driving force and emphasizing stability can be performed.

Also, since the target value of the drive wheel speed in the independent control mode is set to be larger than the target value of the drive wheel speed in the collective control mode, the drive wheel side when the independent control mode is selected acts on the vehicle-mounted engine side. While suppressing the restraining force, avoiding unnecessary reduction of the engine speed as much as possible,
The operation feeling can be improved.

[Brief description of the drawings]

1 shows an embodiment of the present invention. FIG. 1 is a simplified hydraulic circuit diagram showing a braking hydraulic system, FIG. 2 is a block diagram showing a main part of a control means, and FIG. FIG. 4 is a graph showing drive wheel target values in the control mode and the independent control mode, respectively, and FIG. 4 is a graph showing changes in drive wheel target values when switching between the collective control mode and the independent control mode. B _FL , B _FR …… Brake device for drive wheels, V _RHC , V _RLC …… Target value of drive wheel speed in batch control mode, V _RHI , V _RLI …… Target value of drive wheel speed in independent control mode

Claims (1)

(57) [Claims] In a traction control method for a vehicle, wherein a braking force is generated by a driving wheel brake device when an excessive slip tendency occurs in a driving wheel in a driving state, the braking forces of a plurality of driving wheel brake devices are individually controlled. Independent control mode and the collective control mode for collectively controlling the braking forces of a plurality of drive wheel brake devices can be switched, and the target value of the drive wheel speed in the independent control mode is set for the drive wheels in the collective control mode. A traction control method for a vehicle, wherein the speed is set to be larger than a target value of a speed.