JP3396061B2 - Driving force control device for four-wheel drive vehicle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION The present invention relates to a driving force control system for a four-wheel drive vehicle.
Control device, especially the differential limiting class in accordance with the yaw rate.
Driving force by controlling the differential limiting torque of the
Related to controlling the distribution. [0002] 2. Description of the Related Art Conventionally, four-wheel drive vehicles include front wheels and rear wheels.
A transfer device for distributing the driving force to the
Transfer devices usually do not have differential limiting
Although a differential gear mechanism is provided, recently,
In order to be able to control the driving force distribution, together with the differential gear mechanism
Or, instead of a differential gear mechanism, use an electromagnetic multi-plate clutch.
A device provided with a differential limiting device has been proposed. Soshi
In order to ensure steering stability during turning, the differential
The technique of controlling the limiting device using the yaw rate as a parameter
Surgery has also been proposed. For example, Japanese Patent Publication No. 5-14659
In the gazette, sudden changes in spin and steer characteristics occur when turning.
In order to prevent fouling with high responsiveness, the detected
Yaw rate and actual yaw acceleration were obtained from vehicle speed and steering angle
Differential limit to achieve target yaw rate and target yaw acceleration
Vehicle drive system clutch control device to control the device is described
Have been. [0003] However, the yaw rate
The differential limit control (drive
Power distribution), the stability of straight running
In order to secure it, it is desirable to have a four-wheel drive state
Is a state in which the differential between the front and rear wheels is limited as a four-wheel drive state
Has extremely low turnability when driving on tight corners.
Problem. Therefore, the
When yaw rate occurs, cancel the differential
Wheel drive can be considered, but in that case, low friction road
Operation when excessive yaw rate occurs due to surface
Longitudinal stability is reduced. The object of the present invention is four-wheel drive
In a vehicle driving force control device, go straight in a low vehicle speed range
Increased stability, tight corner turning performance,
To improve steering stability when yaw rate occurs.
You. [0004] The four-wheel drive vehicle of claim 1
The driving force control device determines the driving force distribution for the four wheels,
Via the differential limiting clutch means to limit the differential between the front and rear wheels
To control the four wheels according to the yaw rate acting on the vehicle body
In the driving force control device of the driving vehicle, the yaw rate is detected.
Detecting means for outputting, and the yaw ray detected by the detecting means.
Control means for controlling the differential limiting means in response to the
The yaw rate minute area and the yaw rate are determined according to the detected yaw rate.
-Divided into 3 areas: middle rate area and excessive yaw rate area
AndIn the small yaw rate area, the differential
-In the middle range, the differential limiting torque is reduced,
Control characteristics that increase the differential limiting torque in the excessive range
And control means for performing control by the control unit. [0005] [0006] The driving force of the four-wheel drive vehicle according to claim 1
In the control device, the driving force distribution for the four wheels
Depending on the yaw rate via the differential limiting clutch means.
Control, but the yaw rate is detected by the detecting means.
Receiving the detected yaw rate and controlling the yaw rate
In a small area, the differential limiting torque is increased, and the yaw rate
In the range, the differential limiting torque is reduced, and in the excessive yaw rate
Control is performed with control characteristics that increase the differential limiting torque. This
, Increase the differential limiting torque in the yaw rate minute area
By doing so, it is possible to secure straight running stability, and
Tight corners by reducing differential limiting torque in the area
Turning performance and differential in the excessive yaw rate range.
Increased torque limit prevents spinning and lowers steering
Can be secured. Here, in the driving force control device according to claim 2,
Preferably, when the control means is in a predetermined state, the control means
In order to prohibit control based on characteristics, the area where the vehicle speed is
A predetermined area such as an area where the rate of yaw rate change is equal to or more than a predetermined value
Then, there is no restriction on the control characteristics. In the driving force control device according to a third aspect,
The predetermined state is a state in which the vehicle speed is equal to or higher than the predetermined value.
Steering characteristics in areas where yaw rate is likely to occur at high speeds
Since the change can be made smaller, it is possible to prevent a decrease in steering stability.
You. In the driving force control device according to the fourth aspect, the predetermined state
Since the state is a state where the rate of change of the yaw rate is equal to or higher than a predetermined value,
The steering characteristics can be prevented from changing during a sharp turn.
A decrease in longitudinal stability can be prevented. [0009] BRIEF DESCRIPTION OF THE DRAWINGS FIG.
I will explain it. In this embodiment, the front wheel drive
In driving conditions that require differential limiting, the rear wheels are also driven.
An example in which the present invention is applied to a four-wheel drive vehicle of
You. First, the general overall configuration of the four-wheel drive vehicle MC will be described.
Will be explained. As shown in FIG. 1, the four-wheel drive vehicle MC
And a left front wheel axle 5 and a right front wheel axle 6 between the left and right front wheels 1 and 2.
Is provided, and a left rear wheel axle 8 is provided between the left and right rear wheels 3 and 4.
A right rear wheel axle 9 is provided, a left front wheel axle 5 and a right front wheel axle
6 is a front-wheel differential device that allows the left and right front wheels 1 and 2 to be differential
7, the left rear wheel axle 8 and the right rear wheel axle 9
The rear wheel differential 10 allows the left and right rear wheels 3 and 4 to be differentially connected.
Dynamically connected. An engine is provided at the center of the front of the vehicle body (not shown).
Gin and an automatic transmission directly connected to this engine
The power unit 11 is disposed in the front-rear direction.
From the output shaft 12 of the power unit 11 to the front wheel differential 7
A front wheel driving force transmission system 13 for transmitting driving force;
Drive force from the output shaft 12 of the gearbox 11 to the rear wheel differential 10
And a rear wheel driving force transmission system 14 for transmitting the driving force.
The front wheel driving force transmission system 13 includes a gear fixed to the output shaft 12.
The driving force is transmitted from the gear 15 to the gear 16,
The power is transmitted to the front wheel differential 7 through the front wheel drive shaft 17.
It is configured to reach. For the rear wheel drive force transmission system 14
Is a rear wheel drive shaft 1 interlocked with the rear wheel differential 10.
8 and an electromagnetic wave provided between the output shaft 12 and the rear wheel drive shaft 18.
An electromagnetic clutch 19 capable of controlling a differential limiting torque.
Clutch 19 (this corresponds to a differential limiting clutch means)
) Is provided. The electromagnetic clutch 19 is connected to the output shaft 12
A case 20 for rotating the body, and a case
A plurality of clutch plates 21 integrally rotating with the gear 20;
Arranged in case 20 and rotates integrally with rear wheel drive shaft 18
A plurality of clutch disks 22;
A magnetic force acts on the plate 21 and the clutch disc 22.
Electromagnet (this includes the coil 23 and the magnetic path forming member).
M), which is composed of an electromagnet fixed to the vehicle body
I have. No power is supplied to the coil 23 of the electromagnetic clutch 19
In the state, the electromagnetic clutch 19 is in the separated state,
, Only the front wheels 1 and 2 are driven, and the driving force is applied to the rear wheel drive shaft 18.
Is not transmitted, but when the coil 23 is energized,
Drive torque equal to the fastening torque proportional to the magnitude of the
Is transmitted to the rear wheel drive shaft 18 to be in a four-wheel drive state. Next, the control system will be described. Power Yu
A power unit control device 30 for controlling the knit 11,
ABS control device 31 for controlling a brake device (not shown)
(Control device for anti-skid control) and electromagnetic clutch
And a clutch control device 32 for controlling the
You. Further, as the sensors, the rotational speed N1 of the left front wheel 1 is set.
Through a disk 33 that rotates integrally with the left front wheel axle 5.
Left front wheel speed sensor 34 to be detected and rotation speed of right front wheel 2
Degree N2 and the disk 35 which rotates integrally with the right front wheel axle 6.
Of the right front wheel speed sensor 36 detected through the
The rotation speed N3 is set to the value of the disk 3 fixed to the left rear wheel axle 8.
7, a rear wheel speed sensor 38 for detecting the rear left wheel, and a right rear wheel
The rotation speed N4 of the fourth wheel 4 is
A right rear wheel speed sensor 40 detected via a disc 39;
The brake switch 41 and the steering angle θh of the steering wheel 42 are detected.
Outgoing steering angle sensor 43, neutral / inhibit
The switch 44 and the yaw rate ψv acting on the vehicle body are detected.
Yaw rate sensor 45 and an eye provided on the engine.
Dollar switch 46, throttle opening sensor 47 and
A rank angle sensor 48 and the like are provided. The wheel speed sensors 34, 36, 38, 40
The wheel speed signals N1, N2, N3 and N4 of the
Input to the device 31 and the ABS control device 31
ABS signal and wheel speed signal that are turned on during skid control
Nos. N1, N2, N3 and N4 are supplied to the clutch control device 32.
Be paid. Switch signal from the brake switch 41
Signal BR, the steering angle signal θh from the steering angle sensor 43, and the yaw
The yaw rate signal ψv from the late sensor 45 is
Is directly input to the switch controller 32. The neutral / inhibitor switch 4
4 from the switch signal NI and the idle switch 46
Switch signal ID and the throttle opening sensor 47
The throttle opening signal TVO and the crank angle sensor 4
5 from the power unit control device.
It is supplied to the clutch control device 32 via the device 30. Previous
From the clutch control device 32 to the coil of the electromagnetic clutch 19
23 is configured to be able to output the coil current Iout
Yes, the clutch control device 32 has an ignition switch
Is connected to the power supply when the
When the switch is off, the backup battery
49, and the clutch control device 32
Basically, input when the ignition switch is ON.
When the ignition signal IG is input
It is configured to operate in the tailing process.
Sometimes, even if the ignition switch signal IG is OFF
Operate. The clutch control device 32 outputs a detection signal
A / D converter for A / D conversion as needed, detection signal
Waveform shaping circuit and input / output interface for shaping the waveform as necessary
Microcontroller including CPU, ROM, and RAM
Computer outputs coil current Iout to coil 23
And a coil drive circuit. Said my
The ROM of the computer has a four-wheel drive
The fastening torque is controlled in accordance with the running state of the vehicle MC to obtain 4
Drive power distribution for controlling the drive power distribution to the two wheels 1-4
Control program for minute control and accompanying control program
Are input and stored in advance, and are stored in RAM.
Is provided with various memories necessary for the arithmetic processing of the control.
Have been. Here, the control of the electromagnetic clutch 19 is described.
Here is a brief overview. As shown in FIG.
Physical quantities (objects) related to the running state and behavior of the four-wheel drive vehicle MC
Physical parameters), mainly the differential rotation speed of the front and rear wheels
ΔN, yaw rate ψv, and vehicle speed V are used.
You. First, the detected differential rotation speed ΔN is applied to the map M1.
To obtain the fastening torque Tn, and calculate the fastening torque Tn
The gain G1n obtained from the gain characteristic of the
The gain G2n obtained from the gain characteristic of the
And the required fastening torque Tn after the gain change.
Apply a hold process as necessary to reflect the differential rotation speed
Find Luku T1. In parallel with the above, the detected yaw rate Δv
Estimated lateral calculated from vehicle speed V (speed of four-wheel drive vehicle MC)
The acceleration α is applied to the map M4 to determine the fastening torque Tψ.
Therefore, the fastening torque Tψ is determined based on the gain characteristic of map M5.
Gain is changed by the gain G1ψ obtained from the above and the yaw rate is reflected.
Find the fastening torque T2. In parallel with the above, the detected car
Applying the speed V to the map M6 to obtain the engagement torque Tv
The vehicle speed reflecting engagement torque T3 is obtained. Next, the fastening torques T1, T2 and T3 are added.
Applying the total fastening torque Tt to the map M7
To the coil current I, and then to the coil current I,
If necessary, gain Ga and tail
And the output coil voltage
Current Iout and set the coil current Iout to the coil
23. Here, each of the maps M1, M4, M6
Are equivalent to the torque characteristics that set the characteristics of the fastening torque.
And each of the maps M2, M3, M5
The gain characteristic multiplied by the torque matches the set gain characteristic.
That is true. Next, the structure of these maps M1 to M7 will be described.
The configuration will be described. The map M1 is as shown in FIG.
The fastening torque Tn is set using the differential rotation speed ΔN as a parameter.
The differential rotation speed ΔN is detected
The difference between the maximum and minimum wheel speeds of the four wheels obtained is
Determined by the formula. ΔN = Max [N1, N2, N3, N4] -min
(N1, N2, N3, N4) In the map M1, the solid line indicates the torque characteristic during acceleration.
The dashed line shows the torque characteristic at the time of deceleration, and a = 80 to 12
0, b = 40-80, c = 400-500,
is there. Some slippage is preferred when accelerating, but
When decelerating, prevent the wheels from locking and use as many wheels as possible
It is desirable to share the braking force with
It has been set. This can improve braking performance
You. The map M2 shows the vehicle speed V as shown in FIG.
Of the gain G1n using the
The vehicle speed V is the lowest detected wheel
The speed is multiplied by a constant and determined by the following equation. V = min [N1, N2, N3, N4] · 2π · rt · 60/10
00 Here, rt is the dynamic load radius of the tire. Minimum wheel speed
Is generated from wheels gripping the road surface,
The vehicle speed V is determined from the low wheel speed. Map M2
In the area A1, the gain is set to secure the straight running stability.
G1n = 1.0, and in the area A3, when the vehicle is traveling
Gain G1n = 1.0 to prevent spin
In the area A4, the traveling performance during turning is secured,
In order to enable word lift travel, the gain G1n =
It is set to 1.0. In addition, d = 25-35, e = 70
１００100, f = 25-30, g = 40-60, values of the order
It is. The map M2 corresponds to the fastening torque setting characteristic.
Is what you do. Further, in the area A2, a tight corner is turned.
Set gain G1n = 0 to improve turning performance
I have. Also, when turning, the wheel loads on the front wheels 1 and 2
Is large and the rear wheels 3 and 4 have small wheel loads.
3 and 4 tend to skid and tend to oversteer
And the car body spins due to remarkable oversteer
It will be cool. Therefore, in the area A5, the driving force of the front wheels 1 and 2
To lower the grip force (tire lateral force) of the front wheels 1 and 2
And the grip force of the rear wheels 3 and 4 (beside the tires)
Understeer by increasing force)
Gain G to offset the oversteer tendency.
1n = 0 is set. The boundary line L1 is 0.4G
(Where G is the gravitational acceleration) Line corresponding to the lateral acceleration
The boundary lines L2 and L3 are shifted in accordance with the increase in the vehicle speed V.
-Since the rate ψv decreases, the
The torque can be distributed to the front and rear wheels 1 to 4. The map M3 shows the vehicle speed V as shown in FIG.
And the differential rotation speed ΔN as a parameter,
It is a property set. The boundary line L4 is the tire sky.
Due to a decrease in air pressure and the installation of tempered tires,
The differential rotation speed ΔN corresponding to the case where the diameter is reduced by 10%
In the area B1, a decrease in tire air pressure or
Ignores the effect of differential rotation speed ΔN due to mounting of bumper tires
In this case, the gain G2n is set to 0 and the area B2
Then, in order to correspond to the substantially generated differential rotation speed ΔN,
The gain G2n is set to 1.0. Note that h = 7, i
= 70 to 100, j = about 30 to 50, and h =
The value of 7 is detected by the wheel speed sensors 34, 36, 38, 40.
This is the minimum vehicle speed that can be detected from the signal. As shown in FIG.
Holds the fastening torque Tn for a predetermined time to prevent chining
Control, the engagement torque Tn ≧ the set torque Tno (this
Is only 95% of the maximum fastening torque)
Be executed. In this hold processing, Tn ≧ Tn
In the case of o, while measuring time with the counter,
The fastening torque Tn is held during the
After the lapse of the time th, the hold processing is released and the predetermined reduction is performed.
Although the fastening torque Tn is reduced at a small rate, the hold processing is performed.
After the release of the torque, within a predetermined time tf, the fastening torque Tn ≧ set torque
When the time reaches Tno, the next hold processing is
Is executed during the hold time 2th, which is twice the hold time th.
After the elapse of the hold time 2th, the same
Then, the engagement torque Tn is reduced at a predetermined reduction rate. As shown in FIG. 7, the map M4 has an estimated horizontal
The characteristic of the fastening torque Tψ is set using the acceleration α as a parameter.
It is specified. The estimated lateral acceleration α is the yaw rate
ψv and vehicle speed V as parameters
It is. α = (V · 1000/3600) · (ψv · π / 10
0) In this map M4, the running of the winding
Estimated to improve the performance and enable power drift driving
When the lateral acceleration α is equal to or greater than a certain value, a line L5 is shown.
As described above, according to the increase in the estimated lateral acceleration α, the fastening torque Tψ
To a certain value. With turning limit (position of estimated lateral acceleration α = m)
Recently, the rear wheels 3 and 4 have small wheel loads,
The grip force of 3 and 4 decreases, and it tends to oversteer
Therefore, the grip force of the rear wheels 3 and 4 is increased and
Reduced the grip of No. 2 to eliminate oversteer tendency
Above the turning limit, fasten along line L6
Set the characteristics so that the torque Tψ gradually decreases.
You. Thus, when the turning degree is equal to or higher than the turning limit,
Means that the fastening torque Tψ gradually decreases along the line L6
, The fastening torque T 解除 is suddenly released.
Without sudden change in grip force of front and rear wheels 1-4
Operation stability in critical cornering
Can be maintained. In addition, k = 5.5-6.0, m =
6.5 to 7.0, n = 440 to 460, a value of about
You. The map M5, as shown in FIG.
Set the gain G1 特性 characteristics using the number of turns ΔN as a parameter
This map M5 shows the differential during the turning.
This is for improving the response when rotation occurs.
It should be noted that p = 30 to 40, q = 60 to 80, and so on.
You. The map M6 uses the vehicle speed V as a parameter.
The characteristics of the fastening torque Tv are set.
M6 is for ensuring the straight running stability at high speed running
It is. Note that r = 60, s = 70 to 90, t = 100,
The value of the degree. The map M7 shows the total fastening torque Tt and
It is a map in which the relationship of the coil current I is set.
Taking into account the effect of hysteresis of No. 3, the total fastening torque T
When t increases, the coil current I is determined by the broken line L7
When the total fastening torque Tt decreases, a broken line
The coil current I is determined by L8. The ABS processing is performed by the ABS controller 31.
This prevents the wheels from being locked during the execution of the ABS control.
Therefore, in the process of releasing the fastening torque of the electromagnetic clutch 19,
Yes, ABS signal is ON and brake switch signal
When the signal BR is ON, the gain Ga is set to 0,
In other cases, the gain is set to Ga = 1.0.
Is done. The map M8 changes from a running state to a stopped state.
The shock caused by sudden changes in the fastening torque.
Of the gain Gt by tailing processing for
And gradually increase the fastening torque for 3 seconds.
The characteristic is set so as to decrease it. Tailing treatment
Conditions are as follows: ignition switch signal IG = OFF,
Link angle signal CA = 0 (rpm), vehicle speed V = 0, new
Ral / inhibitor signal NI = ON, conditions are satisfied
Executed when Next, in the clutch control device 32,
The clutch control to be performed, which drives four wheels
Driving force distribution to set power distribution appropriately according to driving conditions
A control program for minute control will be described. In the figure,
The symbol Si (i = 1, 2, 3,...) Indicates each step.
It is. Ignition switch signal IG turns ON
Control is started, and first, various detection signals (N1 to N
4, BR, ABS, TVO, CA, NI)
(S1) Then, using the read detection signal,
Dynamic rotation speed ΔN, yaw rate ψv, vehicle speed V, estimated lateral
The acceleration α is calculated as described above (S2). Next, the differential rotation speed ΔN is applied to the map M1.
Then, the engagement torque Tn is calculated (S3), and then the vehicle speed V
And yaw rate ψv applied to map M2 to obtain gain G1
n is calculated (S4), and then the vehicle speed V and the differential rotation speed ΔN
Is applied to the map M3 to calculate the gain G2n.
(S5). Next, it is determined whether hold processing is necessary.
(S6) When the result of the determination is No, the fastening torque T
n is held unchanged (S7), and the determination of S6
If the result is Yes, the fastening process
Tn is corrected (S8). Note that this hold process
The description is omitted because it is as described above. Next
Then, the differential rotational speed reflecting engagement torque T1 is calculated by the following equation.
Is performed (S9). T1 = Tn × G1n × G2n Next, the estimated lateral acceleration α is applied to the map M4.
To calculate the fastening torque Tψ (S10).
Gain G1ψ is calculated by applying rotation speed ΔN to map M5
(S11), and then the yaw rate reflecting engagement torque T2
Is calculated by the following equation (S12). T2 = TψG1ψ Next, the vehicle speed V is applied to the map M6 to be engaged.
The torque Tv is calculated (S13), and then the vehicle speed reflection engagement is performed.
The torque T3 is calculated by the following equation (S12). T3 = Tv Next, a total tightening of the torques T1, T2, and T3 is performed.
The coupling torque Tt is calculated by the following equation (S15). Tt = T1 + T2 + T3 Next, at S16, the total fastening torque T
The coil current I is calculated by applying t to the map M7.
However, when the total engagement torque Tt increases, the map M
7 is calculated based on the line L7, and the total fastening torque is calculated.
When the torque Tt decreases, the line L8 of the map M7
It is calculated based on this. Next, in S17, the ABS signal
Is ON and ABS control is being executed, and the brake switch
Switch BR is ON and the brake is operating.
When the determination result is No, the gain Ga is Ga
= 1.0 (S18), and the result of S17 is determined.
When the result is Yes, the gain Ga is set to Ga = 0.
(S19). Next, in S20, tailing processing is performed.
It is determined whether it is necessary or not.
Switch signal IG = OFF, crank angle signal CA = 0 (r
pm), vehicle speed V = 0, neutral / inhibitor signal N
It is determined as Yes when the conditions of I = ON are satisfied.
Is determined as No when the above conditions are not satisfied.
You. When the determination result is No, the gain Gt is Gt
= 1.0 (S21), and the determination result is
When Yes, the gain Gt is the time measured by the counter.
Is calculated based on the map M8 and the like (S22). Next, in S23, output to the coil 23 is performed.
Is calculated by the following equation.
You. Iout = I × Ga × Gt Next, in S24, the output coil current Iout
Output to the server 23 and thereafter return to S1 to S24
Is repeatedly executed every predetermined minute time.
Become. In the four-wheel drive vehicle MC,
An auto mode that automatically executes the driving force distribution control,
FF mode in which only the front wheels are driven, and the electromagnetic clutch 1
9 or 4WD mode to drive 4 wheels
It is configured to be settable, and it is a mode for high μ road running
And low μ road running mode can be set selectively.
It is. The torque characteristics and the gain characteristics are
These are the characteristics that have been proposed.
This relates to the case of the μ road traveling mode. In addition, low μ
Even in the road running mode, the torque characteristic and the gain
Approximately the same characteristics as the characteristics apply, but the various values (a
~ K, m, n, p ~ t) may be slipped if necessary.
It is appropriately changed to the suppression direction, and the characteristics of the map M4 are changed.
Therefore, the line L5 itself is changed to the left.
You. As described above, this four-wheel drive vehicle MC
Power distribution system executed by the clutch control device 32
In the control, the fastening torque Tn according to the differential rotation speed ΔN
, Engagement torque Tψ according to estimated lateral acceleration α, and vehicle speed V
The fastening torque Tv according to the respective torque characteristic maps
Calculated based on the total torque of the electromagnetic clutch
Running on a slope or turning to control the differential limiting torque of 19
Driving force distribution according to the differential rotation speed ΔN during running and turning
Drive power distribution according to the yaw rate
It is possible to ideally execute the appropriate driving force distribution. Further, the fastening torque Tn is changed from the vehicle speed V to the yaw.
Gain G1 obtained from map M2 based on late ψv
n, the differential speed ΔN, the vehicle speed V, and the
The joint torque Tn taking into account the overall
Can be set off. In particular, in the map M2,
Regarding the area below the speed d, in the yaw rate minute area A1,
By setting G1n = 1.0, the straight running stability is improved.
In the yaw rate intermediate area A2, the
By turning in G1n = 0, turning a tight corner
The turning performance when turning can be improved, and the yaw
In the excessive range A3, the gain G1n should be set to 1.0.
With this, it is possible to prevent spin and improve steering stability
You. Moreover, in the map M2, the line L2
And L3 are characterized in that Δv decreases as the vehicle speed V increases.
The torque according to the increase of the lateral acceleration α.
Torque distribution considering the limit of tire lateral force.
Minutes, the sudden change in tire lateral force during cornering and
Prevent sudden changes in steering characteristics and dramatically improve turning performance
be able to. Further, the fastening torque Tn is differentiated from the vehicle speed V.
The gain is changed with the gain G2n obtained from the rotation speed ΔN.
Therefore, taking into account the correlation between the differential rotation speed ΔN and the vehicle speed V,
The fastening torque Tn can be set appropriately. Further, the fastening torque Tψ is changed to the differential rotation speed ΔN
In order to change the gain with the gain G1n obtained from
I, 車, vehicle speed V, and differential speed ΔN
Thus, fastening torque T # can be appropriately set. Ma
Also, the map M7 taking into account the hysteresis of the coil 23
Based on the coil current I,
Can be set with high accuracy. In addition to the above,
And hunting can be suppressed.
The shock processing at the time of stopping the vehicle can be prevented by the switching process. In the above embodiment, the three types
The luk characteristics are preset in the maps M1, M4, M6
However, some or all of these torque characteristics
You may comprise so that it may be set to an arithmetic expression beforehand. Also,
Thus, the three gain characteristics are represented by maps M2, M3, M
5, but some or all of these gain characteristics
To be set in advance in a table or arithmetic expression.
Is also good. Next, there is a difference from the four-wheel drive vehicle of the above embodiment.
, And developed for a four-wheel drive vehicle that constantly drives the rear wheels 3 and 4.
Another embodiment in which the present invention is applied will be briefly described.
You. However, the same reference numerals are given to the same components as those in the above embodiment.
It is. As shown in FIG. 14, this four-wheel drive vehicle MCA
Are left and right front wheels 1 and 2, left and right rear wheels 3 and 4, and left front wheel
Axle 5, right front wheel axle 6, and both axles 5, 6 are linked
Front differential 50, left rear wheel axle 8, right rear wheel
A shaft 9 and a rear differential 51 for interlocking the two axles 8, 9
And a power unit including an engine 52 and an automatic transmission 53.
Knit and power unit linked to the power unit to drive the front wheels
Transfer device 54 for distributing to 1, 2 and rear wheels 3, 4
And the transfer device 54 is connected to the front differential device 50.
A front-wheel drive shaft 17 for dynamic connection, and a transfer device 54
Drive shaft 18 for the rear wheel for interlocking the
Is provided. The transfer device 54 includes a power unit.
A drive that constantly transmits the driving force from the drive to the rear wheel drive shaft 18
Power transmission mechanism and differential control of driving force from power unit
Electromagnetic multi-plate clutch 55 (this is a center differential
The driving force is transmitted to the front wheel drive shaft 17 through the
It is composed of a differential limiting mechanism and the like. Here, the electromagnetic
The plate clutch 55 will be described. As shown in FIG.
And linked to the output shaft of the power unit via a gear train
Input member 57 that rotates integrally with the shaft member 56, and a front wheel
Between the drive shaft 17 and the outer shaft 58 that rotates integrally.
A multi-plate clutch 59 is provided, and a coil 61 and a magnetic path forming portion are provided.
The electromagnetic actuator 60 made of the material 62 is fixed to the vehicle body side.
Between the electromagnetic actuator 60 and the outer shaft 58
Is equipped with a bearing 63, and the armature 64 is
Fixed to the shaft 58. The coil 61 of the electromagnetic actuator 60
In a state in which no electric power is supplied, the electromagnetic multi-plate clutch 55 is turned off (minutes).
(Disconnected state), and when the coil 61 is energized,
The multi-plate clutch 55 is turned ON (connected state),
Differential torque (ie front wheel drive
Torque) is transmitted to the front wheel drive shaft 17.
Have been. The front differential device 50 includes a differential gear mechanism.
And an electromagnetic multi-plate clutch for limiting differential as described above.
The rear differential 51 is provided with a differential gear mechanism and a front gear.
It consists of an electromagnetic multi-plate clutch for differential
ing. Further, the control system of the four-wheel drive vehicle MCA is
Thus, similarly to the above embodiment, the power unit control device 3
0, ABS control device 31, clutch control device 65, 4
Wheel speed sensors 34, 36, 38, 40, brake switches
Switch 41, steering angle sensor 43, neutral inhibitor
Switch 44, yaw rate sensor 45, idle switch
46, throttle opening sensor 47, crank angle sensor 4
8, etc. are provided, and various detection signals are the same as in the previous embodiment.
Are supplied to the control devices 30, 31, 65 as described above. Furthermore,
The clutch control device 65 has an auto mode and a C mode.
, R mode and F mode
Mode setting device 66 is connected. In the auto mode, the front differential device
The electromagnetic multi-plate clutch of the device 50 is controlled to a free state,
The electromagnetic multi-plate clutch of the center differential 55 and the rear differential 51
Is automatically controlled according to the running state of the four-wheel drive vehicle MCA
Is done. In the C mode, the front differential 50
The electromagnetic multi-plate clutch is controlled to the free state and the center differential
The device 55 is controlled to the completely locked state, and the rear differential 5
1 is the running state of the four-wheel drive vehicle MCA
It is automatically controlled according to. In R mode, CFC
The electromagnetic multi-plate clutch of the differential device 50 is controlled to the free state.
Of the center differential 55 and the rear differential 51.
The multi-plate clutch is controlled to a completely locked state. F mode
, The electromagnetic multi-plate clutch of the front differential 50
, The center differential 55 and the rear differential 51
The plate clutches are respectively controlled to a completely locked state. The center differential 55 is connected to a four-wheel drive vehicle M
Regarding the characteristics of the control that automatically controls according to the running state of CA
A description will be given based on the flowchart of FIG. This difference
The motion restriction control is executed by the clutch control device 65.
This is control, and reference symbol Si in the figure (i = 30, 31,...)
Indicates each step. First after control starts
And various detection signals from sensors (N1 to N4, @v, etc.)
Is read (S30), and then the front wheels 1, 2 and the rear wheels 3, 4
Between the differential rotation speed ΔN, the vehicle speed V, and the yaw acceleration ψa.
Is calculated (S31). However, the differential rotation speed ΔN is
Average value of wheel speeds N1 and N2 of wheels 1 and 2 and cars of high wheels 3 and 4
Calculated as the absolute value of the difference between the wheel speeds N3 and N4 and the average value.
The vehicle speed V is calculated from the minimum wheel speed as described above.
The yaw acceleration ψa is calculated by calculating the time derivative of the yaw rate ψv
Is calculated. Next, a predetermined map (for example, in the above-described embodiment)
Map similar to the map M1 or other general maps.
Applying the calculated differential rotation speed ΔN to
As a result, the fastening torque Tc of the center differential 55 is calculated.
(S32), and then the vehicle speed V is increased to a predetermined vehicle speed V0 (for example,
(25 to 35 km / h) or not (S3).
3) If the result of the determination is Yes, proceed to S40.
However, when the determination result is No,
It is determined whether the yaw acceleration ψa is equal to or greater than a predetermined value C0,
If the result of the determination is Yes, the process moves to S40, but
When the result of the determination is No, the process proceeds to S35. Next, in S35, the yaw rate {v
Is a minute predetermined value C1 (for example, a value of about 8.5 deg / s).
Is determined as follows or not, and the determination result is Yes.
In step S36, a predetermined value ΔT1 is applied to the fastening torque Tc.
Is added, and then the process proceeds to S40. This allows
Yaw rate corresponding to the area A1 of the map M2 of the embodiment.
In a small area, tighten the differential limit to improve the straight running stability.
The coupling torque Tc is set high. Size of S35
If the result is No, the yaw rate is set in S37.
ψv is a very large predetermined value C2 (for example, 50.0 de
g / s) or less.
If the result is Yes, the control proceeds to S38 to determine whether the fastening torque Tc
A predetermined value ΔT2 is subtracted therefrom. Thus, the embodiment
Yaw rate intermediate area corresponding to the area A2 of the map M2
In the same manner as in the previous embodiment,
In order to enhance the rotation, the fastening torque Tc is zero or very small.
Value will be set. Then, from S38 to S4
Move to 0. When the result of the determination in S37 is No,
If the yaw rate is excessive,
A predetermined value ΔT1 is added to the torque Tc, and thereafter, the process proceeds to S40.
Transition. Thereby, the area of the map M2 of the above embodiment is
In the excessive yaw rate region corresponding to A3, the spin
In order to prevent the
The torque Tc is set high. Next, in S40
In the following, the fastening torque Tc set as described above is used.
Is applied to a given map, arithmetic expression, or table,
Calculation of the coil current I that flows through the coil of the differential gear 55
Then, in operation 41, the coil current I is
And the control operation returns to step S30.
Steps S41 to S41 are repeatedly executed at predetermined small time intervals. As described above, the vehicle speed V is equal to or lower than the predetermined vehicle speed V0.
Area, the yaw rate micro area, the fastening torque
Tc, and in the yaw rate intermediate region, the fastening torque Tc is increased.
Set to zero or a small value.
By increasing the torque Tc, the yaw ray
To improve the straight running stability in the micro area
Enhance the turning performance of tight corner turning in the area, yaw
Anti-spin and increased steering stability in the area with excessive lateness
Can be Depending on the traveling state of the four-wheel drive vehicle MCA,
Automatically sets the torque of the electromagnetic clutch of the front differential 50
When controlling, the fastening torque is the same as in the previous embodiment,
Differential rotation speed between left and right front wheels 1 and 2, vehicle speed, yaw ray
And torque parameters set as parameters.
And the gain characteristics associated with each torque characteristic.
The characteristics of the torque characteristics and gain characteristics
The body is set to certain characteristics different from those described above. According to the running state of the four-wheel drive vehicle MCA,
Automatic control of the engagement torque of the electromagnetic clutch of the differential gear 51
When performing the fastening, the fastening torque is
The differential rotation speed between the rear wheels 3 and 4, the vehicle speed, and the yaw rate
Predetermined torque characteristics set as parameters
And the gain characteristics associated with each torque characteristic
However, the torque characteristics and gain characteristics themselves
Are set to predetermined characteristics different from those described above.
Incidentally, instead of the electromagnetic multi-plate clutch in the above embodiment,
This is also applicable to those with hydraulic or pneumatic differential limiting mechanism.
The present invention can be applied similarly, and the present invention
The configuration is not limited to the example but includes various known changes.
Sometimes.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic overall configuration diagram of a four-wheel drive vehicle according to an embodiment. FIG. 2 is an explanatory diagram illustrating an outline of driving force distribution control of a four-wheel drive vehicle. FIG. 3 is a map M1 showing a torque characteristic of a fastening torque Tn.
FIG. FIG. 4 is a characteristic diagram of a map M2 that is a gain characteristic of a gain G1n. FIG. 5 is a characteristic diagram of a map M3 which is a gain characteristic of a gain G2n. FIG. 6 is an explanatory diagram illustrating a hold process. FIG. 7 is a map M4 showing a torque characteristic of the fastening torque T #.
FIG. FIG. 8 is a characteristic diagram of a map M5 which is a gain characteristic of a gain G1 #. FIG. 9 is a map M6 showing a torque characteristic of the fastening torque Tv.
FIG. FIG. 10 is a characteristic diagram of a map M7 for converting a total fastening torque Tt into a coil current I. FIG. 11 is a characteristic diagram of a map M8 that is a gain characteristic of a gain Gt of the tailing process. FIG. 12 is a part of a flowchart of driving force distribution control. FIG. 13 is the remaining part of the flowchart of the driving force distribution control. FIG. 14 is a schematic overall configuration diagram of a four-wheel drive vehicle according to another embodiment. 15 is a sectional view of the center differential of the four-wheel drive vehicle of FIG. FIG. 16 is a flowchart of differential limiting control for the center differential of the four-wheel drive vehicle of FIG. 14; [Description of Signs] MC Four-wheel drive vehicle 19 Electromagnetic clutch 32 Clutch control device 34, 36, 38, 40 Wheel speed sensor 45 Yaw rate sensor MCA Four-wheel drive vehicle 50 Front differential device 51 Rear differential device 55 Center differential device (Electromagnetic multi-plate clutch) 65 Clutch control device

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-96969 (JP, A) JP-A-2-20446 (JP, A) JP-A-4-19230 (JP, A) JP-A-62-162 198522 (JP, A) JP-A-6-72170 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B60K 17/34-17/35 B60K 41/00

Claims (1)

(57) [Claims 1] Driving force distribution to four wheels is controlled by differential limiting clutch means for limiting differential between front and rear wheels.
A driving force control device for a four-wheel drive vehicle that controls the yaw rate according to a yaw rate acting on a vehicle body, wherein: a detecting means for detecting the yaw rate; Means, the detected yaw ray
Yaw rate minute area and yaw rate intermediate area
Control that divides into three areas of excessive yaw rate , increases differential limiting torque in small yaw rate area , lowers differential limiting torque in middle yaw rate area, and increases differential limiting torque in excessive yaw rate area Means for controlling the driving force of a four-wheel-drive vehicle .