JP3318420B2 - Driving force distribution control device for automobile - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving force distribution control device for an automobile.

[0002]

2. Description of the Related Art Some automobiles have been proposed in which a drive power distribution ratio from a power unit to right and left wheels is variable. Japanese Unexamined Patent Publication Nos. H4-129837 and H4-356233 describe that the torque distribution ratio to the left and right wheels is controlled so that the actual yaw rate acting on the vehicle body becomes the target yaw rate. One that performs so-called yaw rate control has been proposed. Performing such yaw control is preferable in terms of enhancing the steering stability of the vehicle.

Japanese Patent Application Laid-Open No. Hei 4-2528 discloses that while the traveling state of a vehicle is improved by controlling the transmission torque distribution to each wheel, if the traveling state cannot be improved by controlling the transmission torque, There has been proposed one in which the engine output is reduced, that is, the vehicle speed is reduced so that the vehicle behaves in a safe direction.

Japanese Unexamined Patent Publication No. 4-85138 proposes a technique for reducing the difference in transmission torque between wheels when the detected moment is equal to or larger than an allowable value. Japanese Patent Laying-Open No. 4-5134 proposes that torque distribution control for each wheel and output control of an engine are performed in cooperation with each other according to the road surface μ.

[0005]

However, when performing the yaw control, it is sometimes difficult to sufficiently enhance the steering stability only by controlling the torque difference between the left and right wheels. In other words, the torque difference required to make the actual yaw rate the target yaw rate is theoretically calculated, but in order to realize this calculated torque difference quickly, the right and left Controlling the torque distribution between the wheels alone may not be sufficient.

More specifically, the transmission torque that can be input to the left and right wheels is uniformly determined by the engine output (generated torque) according to the accelerator opening. The maximum torque difference obtained between the wheels will be limited to this input torque range,
In some cases, it is difficult to quickly converge on the target yaw rate.

Although the yaw rate control is one of the effective methods for improving the steering stability, it is necessary to improve the steering stability in various modes only by the yaw rate control. There is a limit.

Accordingly, it is an object of the present invention to provide a driving force distribution control for an automobile in which the yaw rate control and the output control of the power unit are coordinated so that the steering stability can be more sufficiently improved. It is to provide a device.

[0009]

Means for Solving the Problems To achieve the above object, the present invention has the following configuration. That is, as described in claim 1 of the claims,

[0010] Torque adjusting means for adjusting the torque distribution ratio from the power unit to the left and right wheels, and the torque adjusting means so that the actual yaw rate acting on the vehicle body becomes the target yaw rate. And an output of the power unit which is increased in accordance with an increase in the rate of change of the target yaw rate. When the output of the power unit reaches a predetermined value, the target yaw rate is increased. And output control means for maintaining the output of the power unit at a predetermined value regardless of an increase in the rate of change of the power unit.

[0011]

According to the first aspect of the present invention,
If the rate of change of the target yaw rate is large, it means that the driver is performing an operation that changes the behavior of the vehicle. In such a case, by increasing the output of the power unit, It is possible to improve the followability to the target yaw rate, obtain a yaw motion according to the driver's intention, and enhance the steering stability.

Further, according to the present invention, it is possible to prevent a situation in which the output of the power unit becomes excessive.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the accompanying drawings. Overview of FIG. 1 (FIG. 1) In FIG. 1, 1FL is a front left wheel, 1FR is a front right wheel, 1R.
L is a left rear wheel, and 1RR is a right rear wheel. Reference numeral 2 denotes an engine as a power unit. The driving force of the engine 2 is constantly transmitted to the front drive shaft 6 via the automatic transmission 3 and the gears 4 and 5. The driving force from the engine 2 input to the front drive shaft 6 is transmitted from the differential device 7 to the left front wheel 1 via the left drive shaft 8L.
FL, and is transmitted to the right front wheel 1FR via the right drive shaft 8R. As described above, the automatic transmission 3 includes a torque converter and a multi-speed gear mechanism.

A rear drive shaft 9 is connected to the front drive shaft 6 via a central clutch 14C. A rear intermediate shaft 10 is linked to the rear drive shaft 9 via gears 11 and 12. The left rear wheel 1RL is connected to the rear intermediate shaft 10 via a left clutch 14L and a left drive shaft 13L.
And the right clutch 14R and the right drive shaft 1
The right rear wheel 1RR is connected via 3R.

A control valve 1 is provided in the hydraulic supply / discharge paths 15L, 15R, 15C for the clutches 14L, 14R, 14C.
6L, 16R or 16C is connected. By controlling each of the control valves 16L, 16R, 16C independently, the engagement force (engagement hydraulic pressure) of each clutch 14L, 14R, 14C is independently controlled.

As will be described later, the left and right clutches 14L,
By making the fastening force of the 14R variable, the left and right rear wheels 1
The driving force distribution ratio between RL and 1RR is changed. In the embodiment, the central clutch 14C is set so that a predetermined or more fastening force is always applied to the center clutch 14C so that the center clutch 14C is always driven by four wheels. The engaging force of the central clutch 14C, that is, the front and rear torque distribution ratio, may be a fixed value, or may be varied using the vehicle speed or the difference in the amount of slip between the front wheels and the rear wheels relative to the road surface as parameters. It can also be. To make the front and rear torque distribution ratio always the same,
Instead of the center clutch 14C, for example, a center differential including a planetary gear mechanism or the like may be used.

In FIG. 1, reference numerals UM and U1 to U4 denote control units each using a microcomputer, and the control unit MU determines a drive power distribution ratio between the left and right rear wheels 1RL and 1RR. Control. The control unit U1 is for performing a shift control, and the control unit U2 is for performing a fuel injection amount control and an ignition timing control of the engine 2. The control unit U3 is for ABS control for preventing the wheels from locking during braking, and controls the braking force adjusting unit 17 for independently adjusting the braking force to each wheel. This adjusting unit 17 is used to control the braking force (brake hydraulic pressure) for each wheel.
Can be adjusted independently, and the brake fluid pressure can be increased when the brake pedal is depressed.
The brake fluid pressure can be adjusted even when the brake pedal is not depressed and the brake pedal is not operated, as well as the pressure reducing and holding functions. The control unit U4 is for controlling damping force of a suspension damper (not shown) and controlling an active suspension.

The control unit UM includes a control module described later.
Manual switch 21 for manual selection of a key
, Signals from various sensors and switches are input (sensors for detecting these signals are collectively indicated by reference numeral 22). The sensors 22 include those that detect at least the following elements. That is, the yaw rate acting on the vehicle body, the vehicle speed, the steering angle,
Lateral G (lateral acceleration) acting on the vehicle body, the rotational speed of each wheel (wheel speed), the gear position of the automatic transmission 3 (identifying whether the vehicle is moving forward or backward), the tire pressure of each wheel (load difference and puncture) Detection), identification of whether or not a tempered tire is mounted, identification of bad road or good road, road surface μ (detecting the left and right road surfaces μ independently), acceleration and deceleration of the vehicle (for example, accelerator opening) And the front and rear G of the vehicle body), and the inclination angle of the road surface in the vehicle traveling direction (inclinometer).

The sensors 22 may be independently set for the control unit MU, or may use signals from other control units U1 to U4. It is to be noted that whether or not the road is rough is determined, for example, when a suspension stroke of a predetermined amount or more occurs a predetermined number of times within a predetermined time, or when a vertical stroke G of a predetermined size or more acting on the vehicle body is generated within a predetermined time. When it occurs more than a predetermined number of times,
It can be determined that the road is bad, and the degree of the bad road can also be detected.

The control mode selection manual switch selects one of the following four control modes. The selected control mode is easily visible from the driver, such as an instrument panel. It is displayed on the display device 23 provided at the position. The above four control modes are "auto mode",
"Yoret mode", "LSD (differential limit) mode"
And "Stack mode".

In the yaw mode, the actual yaw rate acting on the vehicle body is a predetermined target yaw rate.
The control mode is such that the target yaw rate is other than zero (Δt control) and when the target yaw rate is zero (Δ0).

The LSD mode has left and right rear wheels 1RL and 1R.
R to control the input torque to the right rear wheels 1RL and 1RR in accordance with the torque distributed to the rear wheels (right and left wheels). Control to prevent the torque difference between them from becoming larger than a predetermined value) and a torque-sensitive control.

The stack mode is a mode for coping with a situation in which the vehicle is stuck, that is, in a state where the vehicle is stuck in mud or the like and cannot easily escape, or in a case where such a state is likely to be dropped.

The auto mode is based on the above two types of "Yore
In this control, a total of five control modes including a "def mode" are added to the four control modes of the "to mode" and the two types of "LSD mode". The differential mode controls the torque distribution ratio to the left and right rear wheels 1RL, 1RR to be equal.

Details of each control mode The contents of control in each of the above control modes will be described with reference to FIGS. In each control mode, the amount of torque adjustment for the left and right rear wheels 1RL and 1RR is finally determined independently, but "rl" used in the following description or in the drawings is for the left rear wheel 1RL. Indicates, "rr"
Is a suffix for the right rear wheel 1RR. In the stack mode, the transmission torque L to the left and right rear wheels 1RL, 1RR is set as the maximum torque transmission amount of the clutches 14L, 14R. This point will be described later in a flowchart. explain.

(1) Yaw mode (FIGS. 2 and 3) FIG. 2 calculates the torque adjustment amounts for the left and right rear wheels 1RL and 1RR when the target yaw rate is set to a value other than zero. It is for. In FIG. 2, in step N1, the actual yaw rate acting on the vehicle body is the actual yaw rate.
The target yaw rate Δt is determined based on the vehicle speed V, the steering wheel angle θ, the lateral G (lateral acceleration), and the stability factor A determined in step N2. In determining the target yaw rate Δt, the equation shown in step N1 is used (where L is the wheel of the automobile).
As the stability factor A is larger, the target yaw rate Δt is made smaller, and the steering stability is set to be higher. The determination of the stability factor A will be described later.

In step N3, the actual yaw rate
And the target yaw rate {t} are determined. In step N4, the deviation △ calculated in step N3
Dead zone processing is performed on
Δt is set as zero. The setting of the dead zone is such that the width is wide at low vehicle speeds and narrow at high vehicle speeds.
The steering stability at a high vehicle speed can be sufficiently satisfied. Then, in step N5, the torque adjustment amount ΔTψt is determined by the feedback control based on the deviation Δt. The feedback control is PD control (proportional or differential control) in the embodiment. The torque adjustment amount {T} determined in step N5
t is the torque adjustment amount for the right rear wheel 1RR as it is {T} t
rr, and the value whose sign is inverted in step N6 is set as the torque adjustment amount ψTψtrl for the left rear wheel 1RL.

The stability factor A is determined as shown in FIG. 3 (F1 to F5 in FIG. 3 are control constants, respectively). That is, in step N11, the first value a1 is determined based on the vehicle speed V, the reference vehicle speed V0, and the control constants F1 and F2. Step N12
, Based on the steering angle θ and the control constants F3 and F4,
A second value a2 is determined. Further, from Step N13
The third value a3 is determined by the processing of N16, and each value a
The stability factor A is calculated by adding 1 to a3 in step N17.

In step N13, the vehicle speed V, the steering angle θ, the reference stability factor A0, and the wheel
The theoretical lateral acceleration Glt is determined based on the distance L. In step N14, the difference ΔG is calculated by subtracting the actual lateral acceleration G from the theoretical lateral acceleration Glt. In step N15, the control constant F5 is determined based on the absolute value of the deviation ΔG (in the dead zone processing of the deviation ΔG,
When the absolute value of the deviation ΔG is equal to or smaller than ΔG0, the control constant F5 is set to zero.) In step N16, the case where the product of the yaw rate and the vehicle speed V is equal to or greater than zero and the case where the product is less than zero is divided into two cases. Thus, the third value a3 is determined.

(2) Yaw mode (FIG. 4) FIG. 4 shows a control system for determining the amount of torque adjustment when the target yaw rate # 0 is set to zero. That is, after the actual yaw rate is inverted in step N21, dead zone processing is performed in step N22 (corresponding to N4 in FIG. 2,
This dead zone processing may be eliminated in order to enhance the straight running stability). In step N23, the target yaw rate ψ0
Is set to zero, the torque adjustment amount {T} 0 is calculated. Then, this △ ψ0 is directly used as the torque adjustment amount △ Tψ0rr for the right rear wheel 1RR, and the value after sign inversion in step N24 is used as the torque adjustment amount △ Tψ0rl for the left rear wheel 1RL.

(3) Differential mode (FIG. 5) FIG. 5 shows a control system for equalizing the torque distribution ratio to the left and right rear wheels 1RL, 1RR.
In N32, the value obtained by halving the distribution torque Tr to the rear wheels is the torque adjustment amount for the left and right rear wheels 1RL, 1RR.
Tdrr and △ Tdrl.

(4) Rotational speed sensitive LSD mode (FIG. 6) FIG. 6 shows the left and right rear wheels 1R in the rotational speed sensitive LSD mode.
FIG. 4 is a system diagram for determining a torque adjustment amount for L and 1RR. In FIG. 6, the left and right rear wheels 1RL, 1RR
Values Srr and Srl indicating the amount of slip on the road surface
In the embodiment, the slip value S is calculated by “(vehicle speed−wheel speed) / wheel speed”. In this case, the vehicle speed may be a ground speed (for example, a vehicle speed determined by using a navigation system using an artificial satellite to determine the position of the vehicle), or a value indicating the lowest wheel speed among the four wheels. The vehicle speed may be used.

The deviation ΔS between the slip values Srr and Srl of the left and right rear wheels 1RL and 1RR is determined in step N41. In step N42, the torque adjustment amount ΔTw according to the deviation ΔS is determined based on the map shown here. In this step N42, a dead zone process is also performed, but the gain α for setting △ Tw in an area other than the dead zone is, for example, a slip value S (left / right average value, left or right larger one, left or right smaller slip value). Either one can be appropriately selected according to the required degree of differential limitation), and the smaller the value, the lower the sensitivity (lower the sensitivity). The torque adjustment amount ΔTw determined in step N42
Is set as a value △ Twrl for the left rear wheel 1LR as it is, and the sign is inverted at step N43 to be set as a value △ Twrr for the right rear wheel 1RR.

(5) Torque-sensitive LSD mode (FIG. 7) FIG. 7 shows the left and right rear wheels 1R in the torque-sensitive LSD mode.
FIG. 4 is a system diagram for determining a torque adjustment amount for L and 1RR. In FIG. 7, the distribution torque Tr to the rear wheels
On the basis of the left and right rear wheels 1 as shown in step N51.
The torque adjustment amounts △ Ttrr and △ Ttrl for RL and 1RR are determined. In this determination, when the distribution torque Tr to the rear wheels is smaller than a predetermined value, ΔTt is set to a small constant value, and when the distribution torque Tr is large, ΔTt gradually increases as the distribution torque Tr increases. To be increased.

Next, the control contents of the control unit MU will be described with reference to the flowcharts of FIGS. 8 to 14. Indicates a step. First, FIG.
In the chart, after various information is input at P1, the torque generated by the engine 2 is theoretically calculated at P2 in a known manner. It should be noted that a torque sensor for detecting the torque generated by the engine 2 may be separately provided. In P3, which control mode
It is determined whether to perform control in the control mode. In P4, the control amount in the determined control mode is calculated, and in P5, the calculated control amount is output.

The contents of P3 and P4 are shown in the flowchart of FIG. In FIG. 9, after the operation state of the switch 21 (control mode selection state) is read at P11, the control mode selected by the determination processing of P12 to P15 is determined, and P16 to P19 are performed. In, a control value corresponding to the currently selected control mode is calculated. Then, in P20, determination control described later is performed.

The control value in the auto mode at P16 in FIG. 9 is calculated based on the flowchart shown in FIG. In FIG. 10, at P21, FIGS.
As described with reference to FIG. 7, the control values in the above five control modes are calculated. In P22, the gain values k1 to k5 indicating the weights in the respective control modes are determined as described later. In P3, the gain value is corrected as described later. Then, in P24, the torque adjustment amount ΔT1 is determined based on the calculation amount according to each control mode and each corrected gain value.

According to the judgments of P25 to P27, the condition is that the ABS control is not being performed and the brake pedal is not being depressed, and that the brake pedal is not being failed.
In P28, the current transmission torque T is determined by adding the adjustment amount ΔT1 calculated in P24 to the previous torque value T. Further, when the ABS control is being performed and the brake pedal is being depressed, or when a failure occurs, the current transmission torque T becomes 0 in P29.
Is set to Note that the processing shown in FIG. 10 is performed independently for the left and right rear wheels (this is shown in FIGS. 11 to 1).
The same applies to other control modes shown in FIG.

FIG. 11 shows details of P17 in FIG. Since FIG. 11 has control contents (steps) corresponding to FIG. 10, differences from the case of FIG. 10 will be described, and redundant description will be omitted. First, there are three calculation targets in each control mode calculated in P31: ΔTψt related to the yaw rate, ΔTψ0, and ΔTd related to the differential mode. Correspondingly, P32 to P3
The gain values used in 4 are also three of k1 to k3. Then, the result calculated in P34 is ΔT2.

FIG. 12 shows the details of P18 in FIG. Since FIG. 12 has control contents (steps) corresponding to FIG. 10, differences from FIG. 10 will be described, and redundant description will be omitted. First, there are three computation targets in each control mode computed in P41: ΔTw and ΔTt relating to the LSD mode, and ΔTd relating to the differential mode. Correspondingly, P42 to P44
Are also three gain values k3 to k5.
Then, the result calculated in P44 is ΔT3.

FIG. 13 shows the contents of P19 in FIG. In FIG. 13, since the stack is in the stack state,
In P51, the torque adjustment amount ΔTsta is
The maximum value Tmax is set according to the maximum transmission capacity of 4L and 14R. In P52, the gain value ksta is determined according to the vehicle speed according to the map shown here.
In P53, the gain value ksta and the torque adjustment amount ΔT
By multiplying by sta, the final torque adjustment amount △
T4 is calculated. Then, at P54, ΔT4 is directly set as the transmission torque amount.

FIG. 14 shows the above-mentioned P23, P33, P4
The details of the correction of the gain values k1 to k5 in No. 3 will be described (setting of the gain values k1 to k5 before correction will be described later). The gain value correction in FIG. 14 is performed using correction coefficients C1 to C5, where C1 is for k1 correction and C2 is for k1.
C3 is for k3 correction, C4 is for k4
C5 is for correction, and C5 is for k5 correction.

First, in the determinations of P55 to P57, it is determined that none of the four wheels is equipped with a temper tire during forward running (only one wheel is not determined to be a puncture with extremely low air pressure). When the difference between the left and right loads is small (when the difference between the air pressures of the left and right wheels is small), each of the correction coefficients C1 to C5 is set to 1 in P58. In P59, the gain value k before correction is set.
By multiplying 1 to k5 by the correction coefficients C1 to C5, corrected gain values k1 to k5 are obtained.

If it is determined in P55 that the vehicle is not traveling forward, it is determined in P60 whether the vehicle is traveling backward. If the determination in P60 is NO, it is determined that the vehicle is stopped, and in this case, P6
In step 4, the amount of torque transmitted to the left and right rear wheels is set to 0 (the clutches 14L and 14R are released).

If the determination in P60 is YES, in P61, it is determined whether the vehicle speed is 10 km / h or more. If the determination in P61 is NO, in P62, the correction coefficients C3 to C5 corresponding to these controls are set to 1 in order to perform the differential control and the LSD control, and
After the correction coefficients C1 and C2 corresponding to the yaw rate control mode are set to 0, the program shifts to P59.

If the determination in P61 is YES, the correction coefficients C1 and C2 corresponding to these are inverted in order to perform the yaw control even when the vehicle is traveling backward, -C1 and -C.
2 and the other correction coefficients C3 to C5 are set to 1 and P5
Move to 9. In the processing after P63, the direction (turning direction) detected by the yaw rate sensor has an opposite relationship between the forward traveling and the backward traveling, so that the direction detected by this sensor is adjusted to the backward direction. The actual contents of the yaw control are performed in the same manner as in the forward running. Y in P56 or P57
In the case of ES, in P65, only the correction coefficient C3 is set to 1 in order to perform only the differential control, and the other correction coefficients C
After setting 1, C2, C4, and C5 to 0, respectively, P59
Move to.

Determination of gain values k1 to k5 Of the gain values k1 to k5 determined in P22 in FIG. 10, P32 in FIG. 11, and P42 in FIG. 12, only the gain value k3 corresponding to the differential control is always set to 1. Is done. Of the gain values other than k3, a non-zero target value
The gain value k1 corresponding to the speed mode is set as shown in FIG. 15, and the gain value k2 corresponding to the yaw mode with zero as the target value is set as shown in FIG. The gain value k4 corresponding to the sensitive LSD mode is shown in FIG.
The gain value k5 corresponding to the torque-sensitive LSD mode is determined as shown in FIG.

The gain value k1 in the yaw mode having a target value other than zero is set in consideration of the following various factors. As these various elements, the steering angle θ, the vehicle speed V, the road surface μ, and the road surface μ are determined to be a uniform road or a split road having different left and right sides (when one of the right and left is low μ, the road is determined to be a split road). ), Acceleration / deceleration (stationary),
This includes whether the road is good or bad. When determining the gain value k1, maps M1 to M15 are created independently for each of the above elements, and the set value m
1 to m15 are set, and the set values m1 to m15
Is set in a range of 0 to 1 or a range of 0 to 0.5.

The maps M1 and M2 are used for the basic setting, and a value obtained by multiplying the set values m1 and m2 obtained therefrom is used as a first operation value km1. By multiplying the set values m1, m3, m4, and m5 obtained from the maps M1, M3 to M5, a second calculated value km2 is calculated. Maps M1, M
3, set values m1, m3 and m6 to m obtained in M6 to M8
By multiplying by 8, a third operation value km3 is calculated. Set value m1 obtained in maps M1, M9 to M12
And m9 to m12 to obtain a fourth operation value k
m4 is calculated. The fifth calculation value km5 is calculated by multiplying the set values m1 and m13 to m15 obtained from the maps M1, M13 to M15. Then, from the first operation value km1, each of the second to fifth operation values km2 to km
By subtracting 5, 5, the gain value k1 is determined.

As is clear from the setting method shown in each map in FIG. 15, the gain value k1 is set to zero when the vehicle is traveling straight or when the steering angle that can be regarded as traveling straight is small (see map M1). The value is set so that the yaw mode is not substantially performed. Further, even when turning, the gain value k1 is set to zero at the time of starting (see map M2). As is apparent from the maps M3 to M5, on a low vehicle speed, high μ and uniform road, the gain value k1
Is made smaller. Maps M3, M6-M
As is clear from FIG. 8, when the vehicle speed is low, the μ is low, and the degree of acceleration / deceleration is strong and on a good road, the correction for reducing the gain value k1 is performed. As is apparent from the maps M9 to M12, when the vehicle speed is high, the μ is high, and the degree of acceleration / deceleration is strong and the road is uniform, the correction for reducing the gain value k1 is performed. As is clear from the maps M13 to M15, when the vehicle speed is low, the μ is low, and the road is rough, a correction for reducing the gain value k1 is performed.

FIG. 16 to FIG. 18 showing the setting of the gain values k2, k4 or k5 mean that FIG.
5, the detailed description is omitted. As shown in a map M74 in FIG. 18, the gain value k5 for the torque-sensitive LSD control is determined in consideration of the inclination angle in the vehicle traveling direction and when the inclination angle is equal to or more than a predetermined value on an inclined road. k5 is set to be increased.

When the auto mode is selected, instead of using the gain values k1 to k5, using a map as shown in FIG. A decision may be made. In FIG. 19, the vehicle speed and the steering angle are set as parameters, and the line α
The area is divided by 1, β1, and γ1. Then, to set a hysteresis to prevent hunting, the line α
2, β2 and γ2 are set. In FIG. 19, in the small steering angle range, the control in the yaw mode in which the target value is set to zero is selected. In the middle steering angle range, control in a differential mode is selected when the vehicle speed is low, and control in a yaw mode in which a target value other than zero is selected when the vehicle speed is high. In the high steering angle range, when the vehicle speed is low, the distribution ratio fixing control is selected (the driving torque on the turning outer wheel is fixed to a torque distribution larger than the driving torque on the turning inner wheel), and when the vehicle speed is high, a value other than zero is set. Yaw rate to set target value
Is selected.

In the low vehicle speed range, the control in the differential mode and the fixed distribution ratio control can be switched according to the steering angle. However, as the vehicle speed increases, the control in the differential mode is selected. -The memory area is enlarged. In the middle steering angle range, as described above, switching between the control in the differential mode and the control in the yaw mode with a target value other than zero is performed, but as the vehicle speed increases, the differential mode changes. The differential mode area is expanded so that the control in (1) is selected.

Judgment Control (FIGS. 20 to 24) FIGS. 20 to 24 show details of P20 in FIG. 9, and Q indicates a step in the following description. Note that this determination control is set on the assumption that the setting of the transmission torque to the left and right rear wheels 1RL, 1RR cannot be actually realized, and cannot be realized only by controlling the engagement force of the clutches 14L, 14R. When possible, in addition to providing a predetermined limit, the transmission torque to the left and right rear wheels 1RL, 1RR is further optimized by using the braking force or the output correction of the engine.

First, in FIG. 20, which is the main flowchart of the judgment control, in Q1, the calculation torque T (left calculation torque T) obtained as shown in FIGS.
rl and right calculation torque Trr) are read. In Q2, based on the calculated torque T, the clutches 14L, 14R
Is set. In Q3, the braking force is set, and in Q5, the output of the engine 2 is corrected.

Details of Q2 in FIG. 20 are shown in FIG.
First, in Q11, it is determined whether or not the distribution torque Tr to the rear wheels is equal to or greater than zero, that is, whether or not the vehicle is in a driving and running state in which the engine 2 drives the wheels. This Q
If the determination in Step 11 is YES, the engagement force Tcrl of the left clutch 14L is set in Q12 to Q14. That is, when the calculation torque Trl for the left rear wheel 1RL is less than zero, the calculation torque is unrealizable, so the fastening force TCrl is set to zero (Q13), otherwise, the fastening force TCrl is set.
Is set as (the value corresponding to) the calculation torque Trl (Q14). By the processing of Q15 to Q17, the fastening force T for the right rear wheel 1RR is set in the same manner as the left rear wheel 1RL described above.
crr is set.

When the determination in Q11 is NO, that is, when the engine brake is acting, it is determined in Q18 whether the calculated torque Trl for the left rear wheel 1RL is less than zero. . If the determination in Q18 is YES, in Q19, a value obtained by reversing the sign of the calculated torque Trl is set as the engagement force Tcrl of the left clutch 14L. If the determination in Q18 is NO, the engagement force Tcrl of the left clutch 14L is set to zero. Q21-Q2
In No. 3, the engagement force of the right clutch 14R is set in the same manner as in the case of the left clutch 14L described above.

Details of Q3 in FIG. 20 are shown in FIG. First, in Q31, it is determined whether or not the vehicle is in a driving state in which the torque Tor distributed to the rear wheels is equal to or greater than zero. If the determination in Q31 is YES, first in Q32,
It is determined whether the left operation torque Trl is less than zero.
If the determination in Q32 is YES, the clutch 14L cannot transmit the negative torque, and in this case, the value obtained by reversing the sign of the left calculation torque Trl in Q33 is the brake voltage for the left rear wheel 1RL. Key braking force TB rl
Is set as If the determination in Q32 is NO, it is not necessary to adjust the torque using the brake.
, The left rear braking force TBrl is set to zero. Q
From 35 to Q37, the braking force TBrr for the right rear wheel 1RR is set in the same manner as in the case of the braking for the left rear wheel 1RL described above.

When the determination in Q31 is NO, that is, when the engine is in the braking operation, it is determined in Q38 whether the left calculation torque Trl is less than the rear wheel distribution torque Tr. If the determination in Q38 is YES, it is determined whether the right calculation torque Trr is less than the rear wheel distribution torque Tr. When the determination in Q39 is YES, and when Q3
If the determination in step 8 is NO, it is determined that the brake adjustment is unnecessary, and the left brake force TBrl is set to zero in Q40 or Q42. N in the determination of Q39
In the case of O, the left calculation torque Trl is calculated from the rear wheel distribution torque Tr.
Is set as the brake TBrl for the left rear wheel 1RL. In Q43 to Q47, the above-mentioned left rear wheel 1
The braking force TBrr for the right rear wheel 1RR is set as in the case of the RL brake. The brake signal is
Output to the control unit U3, this control unit U3
Thus, the corresponding wheel brake is controlled so as to have the above-described brake force.

The details of Q4 in FIG. 20 are shown in FIG. First, by the processing of Q51 to Q54, the clutch engagement force Tcrl or Tcrr is reduced to the clutch 14L,
It is set to be within the range of the maximum torque transmission amount Tcmax of 4R. In Q55, the left and right clutches 14
When the total value of the respective fastening forces of L and 14R is equal to or less than the rear wheel distribution torque Tr, it is determined that the engine 2 is generating excess torque equal to or more than the transmittable torque of the clutches 14L and 14R, as indicated by Q56. The engine output (engine torque) is reduced by a predetermined subtraction value ΔTe calculated according to the equation. The ΔTe indicating the decrease in the output of the engine 2 is output to the control unit U2, and the control unit U2 controls, for example, to throttle a throttle valve, thereby realizing the ΔTe.

Details of Q5 in FIG. 20 are shown in FIG. 24 as a reference example. First, in Q61, it is determined whether or not the rear wheel distribution torque Tr is equal to or greater than zero. This Q
If the determination at 61 is YES, it is determined at Q62 whether the left calculation torque Trl is greater than the rear wheel distribution torque Tr. If YES in Q62, it is determined in Q63 whether the right calculation torque Trr is greater than the rear wheel distribution torque Tr. YES in this Q64 determination
Is determined to be a time when the generated torque of the engine 2 does not need to be reduced, the reduction ΔTe of the engine output is set to zero in Q64. If the determination in Q63 is NO, in Q65, the engine torque reduction ΔTe is set as a value corresponding to the difference between the left and right calculation torques.

If NO in Q62, it is determined in Q66 whether the right calculation torque Trr is larger than the rear wheel distribution torque Tr. If the determination in Q66 is YES, in Q67, the engine torque reduction △ Te
Is set as a value corresponding to the difference between the left and right calculation torques. If NO in Q66 or NO in Q61, ΔTe is set to zero in Q68.

FIGS. 25 to 28 show the control contents of the engine output correction corresponding to the contents of FIG. 24, respectively. (1) FIGS. 25 and 26 FIGS. 25 and 26 show reference examples. In Q71, the absolute value △ ψ of the deviation between the target yaw rate t and the actual yaw rate 演算 is calculated. You. In Q72, a reference value N according to the vehicle speed is determined from the map shown in FIG. The reference value N is set so as to decrease as the vehicle speed increases.

In Q73, it is determined whether △ ψ obtained in Q71 is larger than the reference value N or not. If the determination in Q73 is YES, in Q74, it is determined whether or not the value obtained by doubling the absolute value of the control amount △ Tψ0 (see FIG. 4) having zero as the target value is larger than the torque Tor distributed to the rear wheels. Is determined. If the determination in Q74 is YES, the above △ ψ is reduced (the actual yaw rate is changed to the target yaw rate t).
In Q75, the value obtained by subtracting Tr from the value obtained by doubling the absolute value of Tψ0 is the increase amount of the engine output (torque) in Q75. It is set as Te. When the determination in Q73 is NO or the determination in Q74 is NO, the process shifts to Q76, and the engine output increase ΔTe is set to zero.

(2) FIG. 27 FIG. 27 shows a control example of the present invention, in which the engine output ΔTe is corrected in accordance with the change rate obtained by differentiating the target yaw rate Δt. . First, in Q81,
It is determined whether or not the target yaw rate Δt is larger than 0. If the determination in Q82 is YES, an increase ΔTe in the engine output according to the change rate of the target yaw rate Δt is determined from the map shown in FIG.

The increase ΔTe set in Q82 is zero when the rate of change of the target yaw rate Δt is less than the predetermined value J,
When it becomes larger than the predetermined value J, it is gradually increased in accordance with an increase in the rate of change of the target yaw rate Δt, and after reaching the upper limit, the upper limit is obtained irrespective of the increase in the rate of change of the target yaw rate Δt. Maintained at the value. If the determination in Q81 is NO, the increase ΔTe in the engine output is determined in Q83 in the same manner as in Q82.

(3) FIG. 28 FIG. 28 shows a reference example, in which the engine output is corrected in accordance with the magnitude relation between the target yaw rate {t} and the actual yaw rate. First, in Q91, the target yaw rate
It is determined whether or not ψt is greater than 0. If the determination in Q91 is YES, in Q92, it is determined whether or not the target yaw rate t is smaller than the actual yaw rate. If the determination in Q92 is YES, the vehicle is off.
Assuming that there is a tendency to bust, in Q93, the value obtained by multiplying the deviation between each of the yaw rates {t and} by a predetermined coefficient K is as follows:
It is set as the engine output decrease ΔTe. Q92
If the determination is NO, the engine output decrease ΔTe is set to 0.

If NO in Q91, Q95 to Q95
The process of step 96 is performed, which corresponds to the process of steps Q92 to Q94, and a duplicate description thereof will be omitted.

Although the embodiments have been described above, the present invention is not limited to this, and includes, for example, the following cases. (1) The torque distribution control between the right and left wheels using the clutches 14L and 14R may be performed only in the control mode of the yaw mode. (2) The torque adjustment between the left and right wheels may be performed only between the left and right front wheels, or may be performed both between the left and right front wheels and between the left and right rear wheels. (3) The automobile may be a two-wheel drive vehicle, in which case,
The vehicle may be either a front wheel drive vehicle or a rear wheel drive vehicle.

[Brief description of the drawings]

FIG. 1 is an overall system diagram showing one embodiment when the present invention is applied to a four-wheel drive vehicle.

FIG. 2 is a diagram showing a control system in a yaw mode in which a target value other than zero is set.

FIG. 3 is a control system diagram for determining a stability factor shown in FIG. 2;

FIG. 4 is a diagram showing a control system in a yaw mode when a target value is reduced to zero.

FIG. 5 is a differential model for equalizing the distribution torque to the left and right wheels.
FIG. 5 is a diagram showing a control system in the mode.

FIG. 6 is a diagram showing a control system of a rotation speed sensitive type LSD mode.

FIG. 7 is a diagram showing a control system in an LSD mode of a torque responsive type.

FIG. 8 is a main flow chart showing an example of torque control;
G.

FIG. 9 is a flowchart showing details of mode determination and control torque value calculation in FIG. 8;

FIG. 10 is a flowchart for obtaining a control torque value in the auto mode shown in FIG.

FIG. 11 is a flowchart for obtaining a control torque value in the yaw mode shown in FIG. 9;

FIG. 12 is a flowchart for obtaining a control torque value in the LSD mode shown in FIG.

FIG. 13 is a flowchart for obtaining a control torque value in the stack mode shown in FIG. 9;

FIG. 14 is a flowchart for performing the gain value correction shown in FIGS. 10 to 12;

FIG. 15 is a control system diagram for determining a gain value k1 shown in FIG. 10 and the like.

FIG. 16 is a control system diagram for determining a gain value k2 shown in FIG. 10 and the like.

FIG. 17 is a control system diagram for determining a gain value k4 shown in FIG. 10 and the like.

FIG. 18 is a control system diagram for determining a gain value k5 shown in FIG. 10 and the like.

FIG. 19 is a diagram showing a setting area of a control mode to be selected in the auto mode, which is used instead of FIG. 10;

FIG. 20 is a flowchart showing details of the judgment control shown in FIG. 9;
Chart.

FIG. 21 is a flowchart showing details of clutch force setting shown in FIG. 20;

FIG. 22 is a flowchart showing details of the braking force setting shown in FIG. 20;

FIG. 23 is a flowchart showing details of the torque capacity limitation shown in FIG. 20;

FIG. 24 is a flowchart showing a reference control example of engine output correction shown in FIG. 20;

FIG. 25 is a flowchart showing another reference control example of engine output correction.

26 is a diagram showing a map for setting a reference value N used for the control of FIG. 25.

FIG. 27 is a flowchart showing a control example of the present invention for engine output correction.

FIG. 28 is a flowchart showing another reference control example of engine output correction.

[Explanation of symbols]

 1RL: left rear wheel 1RR: right rear wheel 2: engine (power unit) 14L: left clutch (torque adjusting means) 14R: right clutch (torque adjusting means 14C: central clutch 16L: clutch engagement force control valve 16R: clutch engagement Force control valve 21: Control mode selection switch 23: Sensors UM: Control unit (for torque control) U2: Control unit (for engine output control)

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-5-262159 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B60K 41/04 F02D 29/02

Claims (1)

(57) [Claims] 1. A torque adjusting means for adjusting a torque distribution ratio from a power unit to left and right wheels, and said torque adjusting means so that an actual yaw rate acting on a vehicle body becomes a target yaw rate. Yo to control the adjustment means - les - the DOO control means, in accordance with an increase of the rate of change of the target yaw rate, the power - with increasing output of the unit, the power unit
When the output of the target yaw rate reaches a predetermined value, the target yaw rate changes.
The output of the power unit is specified regardless of the increase in the conversion rate
A drive power distribution control device for an automobile, comprising: output control means for maintaining a value at a value .