JP2689285B2 - Vehicle differential limiting control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicular differential limiting control device for controlling differential limiting of left and right wheels of a vehicle.

[0002]

2. Description of the Related Art Between the right and left driving wheels of an automobile,
A differential mechanism is provided to allow the differential that occurs when turning, etc., but with this differential mechanism, the load on one of the left and right wheels is in the groove and the friction coefficient with the road surface is extremely small. comes to the other wheel only this one pair of wheels are rotated is longer little rotation, there is the state that can not transmit the driving torque to the road surface occurs.

Therefore, in such a case, a differential limiting mechanism (LSD = Limited Slip Differential) capable of limiting the differential has been developed.

Such differential limiting mechanisms for the left and right wheels include a type proportional to the rotational speed difference between the left and right wheels and a type proportional to the input torque. The right / left wheel rotational speed difference proportional type includes a VC (Viscous Coupling) type LSD that utilizes the viscosity of a liquid and the like, and has an advantage that the traveling stability of the vehicle can be improved.

On the other hand, in the input torque proportional type,
There are friction type ones such as general LOM (lock automatic) type LSD and mechanical type ones such as TORSEN type LSD which utilizes the frictional resistance of the worm gear. is there.

[0006]

However, in each of the differential limiting mechanisms described above, the differential control characteristics are determined by the physical properties and the like, and the differential control is always performed so that the differential control can always be appropriately performed. The characteristics are not adjustable.

The present invention was devised in view of the above problems, and an object of the present invention is to provide a vehicle differential limiting control device capable of appropriately controlling the differential state of the left and right wheels.

[0008]

For this reason, the vehicle differential limiting control system of the present invention is capable of selectively limiting the differential between the left wheel side drive shaft and the right wheel side drive shaft of a vehicle. And a control means for limiting the differential limiting means,
Left wheel side rotation speed detecting means for detecting the rotation speed of the left wheel side drive shaft, right wheel side rotation speed detecting means for detecting the rotation speed of the right wheel side drive shaft, the left wheel side rotation speed detecting means and the right side. An actual rotational speed difference calculation means for calculating an actual rotational speed difference between the left wheel side drive shaft and the right wheel side drive shaft based on each rotational speed detected by the wheel side rotational speed detection means,
The target rotation speed difference setting means for setting a target rotation speed difference between the left wheel side drive shaft and the right wheel side drive shaft, which should be generated according to turning of the vehicle, is provided. The differential limiting force by the differential limiting means increases in proportion to the difference between the actual rotational speed difference calculated by the difference calculating means and the target rotational speed difference set by the target rotational speed difference setting means. Differential limiting force setting means for setting the differential limiting force, and the differential limiting force set by the differential limiting force setting means for the difference between the actual rotational speed difference and the target rotational speed difference. And a proportional relationship adjusting means for increasing the increasing rate as the input torque to the left wheel side drive shaft or the right wheel side drive shaft increases.

[0009]

In the above-described vehicle limited differential control device of the present invention,
The actual rotational speed difference calculation means calculates the actual rotational speed difference between the left wheel side drive shaft and the right wheel side drive shaft based on the respective rotational speeds detected by the left wheel side rotational speed detection means and the right wheel side rotational speed detection means. When the target rotation speed difference setting means sets the target rotation speed difference between the left wheel side drive shaft and the right wheel side drive shaft to be generated according to the turning of the vehicle, the control means,
The differential limiting force setting means is proportional to the difference between the actual rotational speed difference calculated by the actual rotational speed difference calculating means and the target rotational speed difference set by the target rotational speed difference setting means. The differential limiting force is set so as to increase the differential limiting force by the dynamic limiting means. At this time, the proportional relationship adjusting means sets the differential limiting force for the difference between the actual rotation speed difference and the target rotation speed difference. The increasing rate of the differential limiting force set by the means is increased as the input torque to the left wheel side drive shaft or the right wheel side drive shaft increases. By the control of the control means based on the differential limiting force set in this way,
The differential limiting means selectively limits the differential between the left wheel drive shaft and the right wheel drive shaft of the vehicle. Therefore, as the input torque to the left wheel side drive shaft or the right wheel side drive shaft increases, the increase rate of the differential limiting force with respect to the difference between the actual rotation speed difference and the target rotation speed difference increases. When the vehicle is suddenly accelerated from a low speed, the differential between the left and right wheels can be appropriately limited, and a suitably high torque can be transmitted to the road surface.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A vehicle differential limiting control device as an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the overall construction thereof, and FIG. 2 is provided with the differential controlling device. 5 is an overall configuration diagram of a drive torque transmission system, FIG. 3 is a sectional view showing a rear differential serving as a left and right wheel differential, and FIGS. 4A and 4B are sectional views taken along the line AA in FIG. Is a block diagram showing the rotational speed difference corresponding control unit, FIG. 6 is a block diagram showing a rear wheel torque gain correction unit, FIG. 7 is a structural diagram showing a part of the input torque corresponding control unit, and FIG. 8 is its input torque. FIG. 9 is a configuration diagram showing a part of the corresponding control unit, FIG. 9 is a configuration diagram of a portion from the maximum value selection unit to the control current output unit, and FIG. 10 is a configuration diagram showing details of the steering angle detection means.
FIG. 11 is a block diagram showing the details of the vehicle speed detecting means, and FIG.
Is a plan view schematically showing a wheel state for explaining the ideal rotation speed difference, FIG. 13 is a view showing an ideal rotation speed difference setting map, FIG. 14 is a view showing the rotation difference gain setting map,
15 (a) and 15 (b) are diagrams showing the differential corresponding clutch torque setting map, FIG. 16 is a diagram showing an example of the engine torque map, and FIG. 17 is a diagram showing an example of the transmission torque ratio map. FIG. 18 is a center differential input torque setting map, FIG. 19 is a flow chart showing a control flow of the entire vehicle including the device, FIG. 20 is a flow chart showing a control flow of the rear differential, and FIG. 21 is a rotational speed difference thereof. FIG. 22 is a flow chart showing the flow of setting the corresponding clutch torque, and FIG. 22 is a flow chart showing the flow of setting the input torque corresponding clutch torque.

First, referring to FIG. 2, the differential limitation for a vehicle is described.
The overall structure of a drive system of a vehicle equipped with a control device will be described.

In FIG. 2, reference numeral 2 denotes an engine. The output of the engine 2 is transmitted to an output shaft 8 via a torque converter 4 and an automatic transmission 6. The output of the output shaft 8 is transmitted via an intermediate gear 10 to a planetary gear type differential 12 as an actuating device for distributing the engine torque of the front wheels and the rear wheels to a required state.

On the other hand, the output of the planetary gear type differential device 12 is the reduction gear mechanism 19 and the differential gear device 1 for the front wheels.
4 through the axles 17L, 17R from the left and right front wheels 16, 1
8 is transmitted to the left and right rear wheels 24, 26 from the axles 25L, 25R via the bevel gear mechanism 15, the propeller shaft 20, the bevel gear mechanism 21, and the rear differential gear unit (rear differential) 22. It

The planetary gear type differential device 12 includes a sun gear 121, a planetary gear 122 disposed outside the sun gear 121, and a ring gear disposed outside the planetary gear 122, as in the prior art. 123 and
The output of the output shaft 8 of the automatic transmission 6 is input to the carrier 125 that supports the planetary gear 122, and the sun gear 121
Is interlocked with the front wheel differential gear device 14 via the front wheel output shaft 27 and the reduction gear mechanism 19, and the ring gear 123 is interlocked with the propeller shaft 20 via the rear wheel output shaft 29 and the bevel gear mechanism 15. .

In the planetary gear type differential device 14, the output torque of the engine between the front wheels and the rear wheels is restricted by restricting (or limiting) the differential between the front wheel side output section and the rear wheel side output section. A hydraulic multi-plate clutch 28 is attached as a differential limiting device or a differential adjusting device that can change the distribution.

That is, the hydraulic multi-plate clutch 28 includes a sun gear 121 (or a ring gear 123) and a carrier 125.
The frictional force is changed by the control pressure applied to its own hydraulic chamber, and the differential between the sun gear 121 (or the ring gear 123) and the carrier 125 is restrained.

Therefore, the planetary gear type differential 12 is
By appropriately controlling the hydraulic multi-plate clutch 28 from a completely free state to a locked state, the torque transmitted to the front and rear wheels can be reduced from about 32:68 to 50:50 for the front and rear wheels. It can be controlled between. Front wheel in completely free condition: rear wheel value: approx. 3
2:68 can be defined by setting the tooth ratio of the input gears on the front wheel side and the rear wheel side of the planetary gears. In this case, when the pressure in the hydraulic chamber of the hydraulic multi-plate clutch 28 is zero and completely free, It is set to be about 32:68.

The ratio in the completely free state (about 3)
2:68) changes depending on the load balance between the front wheel system and the rear wheel system and the like, but usually takes such a value. Further, when the pressure in the hydraulic chamber is set to the set pressure (9 kg / cm ² ) and the hydraulic multi-plate clutch 28 is in the locked state and the differential limit becomes substantially zero, the torque distribution between the front wheels and the rear wheels is reduced. , 50: 5
It becomes 0 and it is in a directly connected state.

The details of the rear differential 22 will be described later.

Reference numeral 30 denotes a steering wheel angle sensor for detecting the rotation angle from the neutral position of the steering wheel 32, that is, the steering wheel angle θ, and reference numerals 34a and 34b denote lateral accelerations Gyf and Gyr acting on the front and rear portions of the vehicle body, respectively. In this example, the lateral acceleration data is obtained by averaging two pieces of detection data Gyf and Gyr. In this example, only one lateral acceleration sensor 34 is provided near the center of gravity of the vehicle body, and this detection value is obtained. May be used as the lateral acceleration data. 3
6 is a longitudinal acceleration sensor for detecting a longitudinal acceleration Gx acting on the vehicle body, and 38 is a throttle opening θ of the engine 2.
t is a throttle position sensor for detecting t, 39 is an engine key switch of the engine 2, 40, 42, 44, 4
Left front wheel 16 is 6, respectively, the right front wheel 18, left rear wheel 26, a wheel speed sensor for detecting a rotational speed of the right rear wheel 28, this
Among them, 46 and 44 are rear wheel speed detecting means (front wheel speed).
Sensor), in particular, 46 is a left-wheel-side rotational speed / speed detecting means.
The reference numeral 44 denotes a right wheel side rotational speed detection means. The outputs of these switches and each sensor are input to a controller 48 as control means .

Reference numeral 50 denotes an anti-lock brake device, which operates in conjunction with a brake switch 50A. That is, when the brake switch 50A is turned on when the brake pedal 51 is depressed, an antilock brake operation signal is output in conjunction therewith, and the antilock brake device 50 is operated. Further, when the operation signal of the anti-lock brake is output, a signal indicating the state is simultaneously output to the controller 4.
8 is input. Reference numeral 52 denotes a warning lamp that lights based on a control signal from the controller 48.

The controller 48 has a CPU, a ROM, a RAM, an interface, etc., which are not shown, but are required for the control described later.

Reference numeral 54 denotes a hydraulic pressure source, and 56 denotes a pressure control valve system (hereinafter referred to as a pressure control valve system) interposed between the hydraulic pressure source 54 and the hydraulic chamber of the hydraulic multi-plate clutch 28 and controlled by a control signal from a controller 48. Abbreviated as control valve). In addition, this car is equipped with an automatic transmission, and the code 160
Is a shift lever position sensor (shift range detecting means) for detecting a selected shift range of the shift lever 160A of the automatic transmission, and this detection information is also sent to the controller 48.

Further, the engine speed N detected by the engine speed sensor (engine speed sensor) 170
e and the transmission rotation speed Nt detected by the transmission rotation speed sensor (transmission rotation speed sensor) 180 are also sent to the controller 48.

In this example, a traction control system 151 is also provided. That is, the engine 2 has the main throttle valve 152 whose opening is controlled according to the amount of depression of the accelerator pedal 162, and constitutes an accelerator pedal system engine output adjusting device together with the accelerator pedal 162 and the coupling measure. .

An auxiliary throttle valve 153 as engine output control means controlled independently of the accelerator pedal system engine output adjusting device is provided in series with the main throttle valve 152 in the intake passage of the engine 2. . The auxiliary throttle valve 153 is driven by a motor, and the motor is driven and controlled based on detection results of the rear wheel speed sensors 44 and 46, the front wheel speed sensors 40 and 42, the engine speed sensor 170, the engine load sensor 172, and the like.

The above-described rear differential (rear differential) 22 is provided with a differential limiting device 23, and is configured as shown in FIG.

That is, as shown in FIG.
Are connected to the rear end of the propeller shaft 20, and the drive pinion gear 402 is supported by the input shaft 401 so as to rotate integrally therewith. The input shaft 401 is rotatably supported in the front part of the case 413 via a bearing 412.

A crown gear 403 meshes with the drive pinion gear 402.
The power transmission annular member 404 is
And the first housing 405 is integrally coupled.

The rear differential 22 is a planetary gear type differential using a planetary gear mechanism, and includes a power transmission annular member 404 and an annular member 404 formed therein.
A ring gear 407 formed on the inner peripheral surface of the left wheel 24
A sun gear 408 spline-coupled to the axle 25L of
A carrier 409 that is spline-coupled to the axle 25R of the right wheel 26, and shafts 410a and 410b on the carrier 409.
Planetary gears 411a, 41 attached via
1b.

Therefore, the rotational torque input from the input shaft 401 passes through the drive pinion gear 402 and the crown gear 403, and then from the ring gear 407 of the annular member 404 to the planetary gears 411a and 411b and the carrier 4.
09 to the axle 25R of the right wheel 26 and the planetary gears 411a, 411b and the sun gear 4
08 to the axle 25L of the left wheel 24.

Further, a second housing 406 is provided on the right side of the carrier 409, and the second housing 406 is connected to the annular support member 4 via a bearing 428.
18 supported.

The rear differential 22 is provided with a differential limiting device 23. The differential limiting device 23
A multi-plate clutch 414 as a differential limiting mechanism; a driving device 417 for driving the multi-plate clutch;
Differential control unit 48 of the controller 48 for controlling the
a.

That is, the multi-plate clutch 414 is provided inside the annular member 404, and the holder portion 415a supporting one clutch disc 414a has the shaft 410a,
The clutch disc 414a is coupled to the carrier 409 via the base 410b so that the clutch disc 414a rotates integrally with the carrier 409, and the holder 415b supporting the other clutch disc 414b is formed on the hollow shaft 416 provided with the sun gear 408. The clutch disk 4
14b is configured to rotate integrally with the sun gear 408.

Further, the driving device 417 is connected to the carrier 40.
9 and a second housing 406, and a force direction conversion mechanism 429 and an electromagnetic clutch mechanism 430 that drives the force direction conversion mechanism 429. In addition,
Since the rear differential 22 limits the differential by an electromagnetic clutch mechanism, an electromagnetically controlled differential (EMC)
D: Electro Magnetic Controlled Differentia
l).

As shown in FIG. 3, the force direction changing mechanism 429 includes a ball 421 interposed between the carrier 409 and the second housing 406, and as shown in FIG.
A diamond-shaped (or rectangular) chamber 42 for accommodating the ball 421
5, the chamber 425 includes a groove 422 formed on the carrier 409 side, the carrier 409, and the second housing 40.
6 is formed by a groove 424 formed in the annular member 423 between them. The annular member 423 is interposed between the carrier 409 and the second housing 406, is normally free in the rotational direction with respect to these members, and rotates integrally with the carrier 409 via the balls 421. However, the second housing 406 side (that is,
When receiving the rotation torque of the crown gear 403 and the power transmission annular member 404), a differential rotation is generated with respect to the carrier 409, and the force due to the rotation torque is changed in direction and acts as a pressing force of the clutch 414. It is supposed to.

The second housing 406 is attached to the annular member 423.
An electromagnetic clutch mechanism 430 applies the rotational torque on the side, and the electromagnetic clutch mechanism 430 is connected to the annular member 423 and the second housing 406 side (the crown gear 403 and the power transmission annular member 404 side). The clutch 427 is interposed between the member 426 and an electromagnetic clutch drive system including a magnet 419 and a solenoid (EMCD coil) 420 as a differential limiting mechanism control means.

That is, the clutch 427 is provided inside the second housing 406, and the magnet 419 is provided further inside the second housing 406, while the magnet 419 is provided outside the second housing 406. , A solenoid 420 capable of attracting the magnet 419 is provided. Thus, when the solenoid 420 operates, the magnet 419
Of the second housing 406 so that the clutch 416 is engaged with the second housing 406.

When the clutch 416 is engaged, the annular member 423 receives the rotational torque of the second housing 406 and tries to rotate integrally with the second housing 406. . At this time, the second housing 406 side (therefore, the sun gear 407 side)
If there is a rotational speed difference (differential rotation) between the and the carrier 409, that is, if there is a rotational speed difference between the left and right wheels,
The annular member 423 makes a differential rotation with respect to the carrier 409, and when the annular member 423 makes a differential rotation with respect to the carrier 409, the ball 421 and the grooves 422, 424 as shown in FIG. The force Δr in the differential rotation direction is converted into a force in a direction orthogonal to the direction, that is, a force F parallel to the axial direction of the rear differential and the axle direction through the inclined surface of the carrier 409. Are driven in the axial direction, and the shafts 410a and 410b and the holder 415a
, The multi-plate clutch 414 is pressed and engaged.

The engagement force of the multi-plate clutch 414 corresponds to the rotational speed difference between the left and right wheels and the magnitude of the electromagnetic force generated by the solenoid 420.
By adjusting the current to zero, the engagement force of the multi-plate clutch 414, and thus the differential limiting force, can be controlled.

The controller 48 is provided with a rear differential control unit 48a for controlling the differential limiting force by adjusting the current to the solenoid 420.

Here, the rear differential control section 48a will be described.

As shown in the block diagram of FIG. 1, the rear differential control section 48a includes sensors (wheel speed sensors 40, 42,
44, 46, steering angle sensors 30a, 30b, 30c, lateral acceleration sensor 34, longitudinal acceleration sensor 36, throttle position sensor 38, engine speed sensor 170,
The clutch torque of the multi-plate clutch 414 is set based on the detection information from the transmission speed sensor 180, the shift position sensor 160, and the like, and the clutch torque is set to the electromagnetic clutch mechanism 430 of the driving device 417 so as to obtain the target clutch torque. Is controlled.

The ABS information, wheel speed,
Steering angle, gear position, comprehensive communication between ABS control unit and engine control unit (SCI communication: SCI =
Data such as Serial Communication Interface) are digitally input, and longitudinal acceleration, lateral acceleration, accelerator opening, hydraulic control for multiple disc clutch, 4WD control unit control, current to electromagnetic clutch of rear differential, etc. are analog input. .

In this apparatus, the setting of the clutch torque of the multi-plate clutch 414 is set to an ideal differential state by focusing on the differential state of the left and right wheels (the rotational speed difference is also expressed as the rotational speed difference). Clutch torque Trn for controlling the vehicle, and an input that is set in proportion to the torque input to the rear wheels so as to obtain a large road surface transmission torque by suppressing wheel slip at the time of sudden start or the like. One is selected from the torque proportional clutch torque Tra, and each of these clutch torques Trn,
The setting unit of Tra will be described in order.

The clutch torque Trn corresponding to the differential is a clutch torque for improving the control accuracy so as to make the vehicle behave in accordance with the driver's intention at the time of turning and for avoiding the tight corner braking phenomenon. In other words, when turning, there is a geometric difference between the left and right wheels and between the front and rear wheels due to the track difference and the body posture.
We want to control the differential between the left and right wheels and between the front and rear wheels so that this differential can be properly tolerated.

By the way, at the time of turning, as a driver's will,
Available information is the required steering angle (pseudo steering angle) δr of the driver.
ef and the vehicle speed (pseudo vehicle speed) Vref, and the differential corresponding clutch torque Trn is set based on the information δref and Vref.

Therefore, the differential corresponding clutch torque Tv
As shown in FIG. 1, the portion related to the setting of the right and left wheel actual rotation speed difference detection unit 500 as the actual rotation speed difference detection means
And ideal rotation speed difference setting means (target rotation speed difference setting
Left and right wheels ideal rotational speed difference setting portion 510 as a stage), and the left and right wheel actual rotational speed difference ΔVrd left and right wheels ideal rotational speed difference ΔV
hr and a differential corresponding clutch torque setting unit 520 as a differential limiting force setting means for setting a clutch torque (differential limiting force) Trn ′ from the hour and a correction for correcting the clutch torque Trn ′ with a rear wheel torque gain k _3. part (k ₃ correction unit) 54
6 is comprised.

The left and right wheel actual rotation speed difference detection section 500
As shown in FIG. 5, the filters 202c and 202d and the left and right wheel actual rotation speed difference calculation unit 506 are provided. The filters 202c and 202d are used to detect the minute vibration component of the data generated by disturbance or the like from the rotation speed data signals RL and RR of the left rear wheel 24 and the right rear wheel 26 detected by the wheel speed sensors 44 and 46, respectively. Is to get rid of. Further, the left and right wheel actual rotation speed difference calculation unit 50
In No. 6, by subtracting the right wheel rotation speed Vrr of the rear wheel from the left wheel rotation speed Vrl of the rear wheel, the actual rotation speed difference of the left and right wheels [the rotation speed difference of the left and right wheels (the left and right rotation difference: this rotation difference is the rotation in the rear differential) ΔVrd is calculated.)

The right and left wheel ideal rotational speed difference setting section 510 includes a driver required steering angle calculating section (pseudo steering angle calculating section) 212 as steering angle detecting means, and a driver required vehicle speed calculating section as vehicle speed data detecting means. Section (pseudo vehicle speed calculation section) 216
And an ideal rotation speed difference setting unit 518 as an ideal operation state setting unit.

As shown in FIG. 10, the driver-requested steering angle calculating section 212 as the steering angle detecting means includes a steering angle sensor 3
0 (first steering angle sensor 30a, the second steering angle sensor 30b installed in the steering wheel, the neutral position sensor 30c) detects data theta ₁ from, theta _2, based on θn sensor corresponding steering angle .delta.h [= f ( θ ₁ , θ ₂ , θn)]
Sensor corresponding steering angle data setting unit 212a for calculating the value of
A lateral acceleration data calculator 212b that averages the data Gyf and Gyr detected by the lateral acceleration sensors 34a and 34b to calculate lateral acceleration data Gy; a direction of the sensor corresponding steering angle δh and a direction of the lateral acceleration data Gy; And a driver request steering angle setting unit (vehicle speed data setting unit) 212d that sets the driver request steering angle δref according to the comparison result of the comparison unit 212c.

The function δh = f (θ ₁ , θ ₂ , θn) for obtaining the sensor-corresponding steering angle δh depends on the specifications of the steering wheel angle sensor. Further, the sensor-corresponding steering angle δh and the lateral acceleration data Gy are both positive in the right turning direction, for example.

In order to compare the directions of the sensor corresponding steering angle δh and the lateral acceleration data Gy, a function SIG (x) relating to the following direction is set for the detection data x. When x> 0, SIG (x) = 1, when x = 0, SIG (x) = 0, when x <0, SIG (x) = − 1. SIG is compared with the direction of the lateral acceleration data Gy.
(Δh) is compared with SIG (Gy).

When the direction SIG (δh) of the sensor corresponding steering angle δh is equal to the direction SIG (Gy) of the lateral acceleration data Gy, the driver required steering angle setting section 212d sets the sensor corresponding steering angle δh to the driver. The required steering angle (steering angle data) δref is set, and the direction S of the sensor corresponding steering angle δh is set.
IG (δh) and the direction SIG (G
If y) is not equal, 0 is set to the driver's requested steering angle δ.
Set to ref.

The direction SIG (δ) of the steering angle δh corresponding to the sensor
h) and the direction SIG (Gy) of the lateral acceleration data Gy are not equal, the reason why the driver-requested steering angle δref is set to 0 is, for example, when the driver performs a steering operation such as counter-steering, the steering position of the steering wheel. And the actual steering angle (turning state) of the vehicle may be different. In such a case, if the steering angle of the vehicle is set from the steering position of the steering wheel, it is difficult to perform appropriate control.

Therefore, in order to eliminate such a problem, if the direction SIG (δh) of the sensor corresponding steering angle δh and the direction SIG (Gy) of the lateral acceleration data Gy are not equal, the driver's required steering angle is set. Is set to 0.

Thus, the driver's required steering angle δref is
The steering angle δh based on the steering wheel angle is a steering angle that reflects the driver's intention more than the steering angle δy based on the lateral acceleration Gy, for example. Are suitable. For example, if the driver wants to make a larger turn than the current situation, | δh |> | δ
y |, and the steering angle value | δh |
It is possible to increase the magnitude of the ideal rotation speed difference (slip target value) as compared with adopting δy |, while if the driver wants to hold down the current turn, | δh | <| δy | By using | δh |, it is possible to reduce the magnitude of the ideal rotation speed difference (slip target value) as compared with the case of using the steering angle value | δy |.

The driver-requested vehicle speed calculating section 216 calculates the vehicle speed from the wheel speed when a wheel slips.
As shown in FIG. 11, the wheel speed sensors 40, 42, 44,
Left front wheel 16, right front wheel 18, left rear wheel detected by 46
24 , the rotation speed data signals FL, FR, R of the right rear wheel 26
A wheel speed selector 216a for selecting the second largest wheel speed data from the bottom (lower one) of L and RR, and a driver request for setting a driver requested vehicle speed from the selected wheel speed data and the like It comprises a vehicle speed calculation unit 216c.

In particular, the driver-requested vehicle speed calculating section 216c detects the wheel speed data SVW obtained by filtering the wheel speed data selected by the wheel speed selecting section 216a through the filter 216b to remove noise components, and the longitudinal acceleration sensor 36. The vehicle speed during the slip can be estimated from both data SVW and Gx at a certain time before the slip based on the longitudinal acceleration data Gx obtained by removing the noise component by applying the filtered longitudinal acceleration to the filter 216d. .
That is, assuming that the wheel speed data SVW at a certain point in time is V ₂ and the longitudinal acceleration data Gx is a, the theoretical body speed Vref after a time t from this point is Vref = V ₂ + a
It can be calculated by t.

Further, instead of the longitudinal acceleration data Gx, the wheel speed data SVW or the driver's required vehicle acceleration V'ref obtained by differentiating the driver's required vehicle speed Vref with time may be adopted.

The rotation speed data signals FL, FR, R
The second largest wheel speed data from L and RR is adopted because each wheel usually slips toward the over-rotation side in many cases, so the wheel speed of the lowest rotation speed is originally adopted. It is desirable to use the second wheel speed from the bottom in consideration of data reliability. Then, in the ideal rotation speed difference setting unit 518, the driver's required steering angle δref calculated by the driver's required steering angle calculation unit 212 is calculated.
And the driver-requested vehicle speed Vref calculated by the driver-requested vehicle speed calculator 216, the ideal rotational speed difference ΔVhr is set in correspondence with the map shown in FIG.

That is, as for the steering angle, the larger the steering angle, the larger the required rotation difference between the left and right wheels. Therefore, the larger the steering angle data δref, the ideal rotation speed difference ΔVh
The value of r also increases. For example, as the steering angle data δref increases in the right turning direction, the value of the ideal rotation speed difference ΔVhr increases in the forward direction (in the direction in which the left wheel has a higher speed), and the steering angle data As δref increases in the left turning direction, the value of the ideal rotation speed difference ΔVhr increases in the negative direction (in the direction in which the speed of the left wheel is lower). Regarding the vehicle speed, at low vehicle speeds, the value of the ideal rotation speed difference ΔVhr increases as the vehicle speed increases, but at high speeds, the tendency of the ideal rotation speed difference ΔVhr to increase with increasing vehicle speed decreases. That is, at high speed, the ideal rotational speed difference ΔVhr between the left and right wheels is determined mainly according to the steering angle data δref.

Referring to FIG. 12, a description will be given of the rotational speed difference ΔVhr between the left and right wheels due to the difference in the orbit radii of the left and right wheels. The example shown in FIG. 12 is the case of a right turn, in which the right wheel speed on the inside of the turn (turning inner wheel speed) is Vi, the left wheel speed on the outside of the turn (outer wheel speed) is Vo, and the center of the left and right wheels is the center. Where V is the vehicle speed at the portion, R is the turning radius of the vehicle (the turning radius at the center of the left and right wheels), Lt is the interval between the left and right wheels (tread), l is the wheelbase, and the distance between the front wheel center and the center of gravity is If, the distance between the center of the rear wheel and the center of gravity is lr, and the vehicle weight is m. If the vehicle body slip angle β is sufficiently small and cos β ≒ 1 and sin β ≒ β, the rotational speed difference ΔVhr between the left and right wheels is expressed as follows. ΔVhr = Vo−Vi = (Lt / R) · V (1.1) where R = (1 + A · V ² ) · 1 / δ (1.2) where A is a stability factor If the front cornering power is kf and the rear cornering power is kr, A = − (m / 2l ² ) · (lf · kf−lr · kr) / (kf · kr)

As shown in the above equations (1.1) and (1.2),
From the vehicle speed V and the steering angle δ, the ideal rotational speed difference ΔV between the left and right wheels
hr can be calculated. However, the pseudo vehicle body speed Vref and the driver's required steering angle δref are used as the vehicle speed V and the steering angle δ, respectively.

Then, the left and right wheel actual rotational speed difference detecting section 500
The difference between the actual rotational speeds of the left and right wheels ΔVrd detected by the difference between the ideal rotational speeds of the left and right wheels, which is set by the ideal rotational speed difference between the left and right wheels ΔVhr, is subtracted by a subtractor 522 (ΔVrd−
ΔVhr) and the obtained difference ΔVr (= ΔVrd−Δ
Vhr) and the ideal rotation speed difference ΔVhr between the left and right wheels are input as data to the differential corresponding clutch torque setting unit 520.

The differential corresponding clutch torque setting section 520
Left and right wheel actual rotation speed difference ΔVrd and left and right wheel ideal rotation speed difference Δ
The clutch torque Trn ′ is set in accordance with the difference ΔVr from Vhr (= ΔVrd−ΔVhr), and the clutch torque Trn ′ is set depending on whether the left and right wheel ideal rotational speed difference ΔVhr is positive or negative.

(I) When ΔVhr ≧ 0 In this case, it is desired that the speed of the rear wheel be higher than that of the front wheel.
Set.

If .DELTA.Vrd.gtoreq..DELTA.Vhr, the rear wheels are slipping due to overspeed, and it is desired to suppress a rear wheel slip by transferring a part of the engine torque largely distributed to the rear wheels toward the front wheels. . Therefore, the clutch torque T
Trn ′ = a × (ΔVrd−ΔVhr) = a × ΔVr (1.3) so that rn ′ increases in proportion to the magnitude of the difference ΔVr (ΔVrd−ΔVhr) (where a Is a proportional constant).

If ΔVhr>ΔVrd> 0, the front wheels are slipping, so if the clutch torque T
When rn 'is increased, the engine torque distributed to the front wheels increases, and the slip of the front wheels is promoted. For this reason, it is desired to reduce the engine torque distributed to the front wheels by making the differential limitation free. Therefore, in this case, the clutch torque Trn 'is set to 0 to set a so-called dead zone.

If 0.gtoreq..DELTA.Vrd, the front wheels are slipping, and it is desired to reduce the slip of the front wheels by increasing the distribution of engine torque to the front wheels. Therefore, Trn ′ = − a × ΔVrd = −a × (ΔVr + ΔVhr) (1.4) is set so that the clutch torque Trn ′ increases in proportion to the magnitude of ΔVrd (where a is proportional. constant).

FIG. 15A shows a map of the relationship between Trn 'and ΔVr, and the map shows the differential corresponding clutch torque Trn based on the difference ΔVr and the ideal rotational speed difference ΔVhr between the left and right wheels. Can be requested.

When ΔVhr = 0, ΔVhr>
There is no dead zone region where ΔVrd> 0.

(Ii) When ΔVhr <0 In this case, it is desired that the speed of the front wheels be faster than that of the rear wheels.
Set.

If .DELTA.Vrd.gtoreq.0, the rear wheel is over-rotating and slipping, and it is desired to suppress a rear wheel slip by transferring a part of the engine torque largely distributed to the rear wheel toward the front wheel. . Therefore, the clutch torque Trn '
Is set so as to increase in proportion to the magnitude of ΔVrd: Trn ′ = a × ΔVrd = a × (ΔVr + ΔVhr) (1.5) (where a is a proportional constant).

If 0>ΔVrd> ΔVhr, the rear wheel is slipping, so if the clutch torque T
If rn 'is increased, the engine torque distributed to the rear wheels increases, and the slip of the rear wheels is promoted. For this reason, it is desired to reduce the engine torque distributed to the rear wheels by setting the differential limit to free. Therefore, in this case, the clutch torque Trn 'is set to 0 to set a so-called dead zone.

If .DELTA.Vhr.gtoreq..DELTA.Vrd, the front wheels are slipping, and it is desired to reduce the slip of the front wheels by increasing the distribution of the engine torque to the front wheels. Therefore, Trn ′ = − a × (ΔVrd−ΔVhr) = − a × ΔVr (1.6) so that the clutch torque Trn ′ increases in proportion to the magnitude of ΔVr (ΔVrd−ΔVhr). (Where a is a proportional constant). A map of such a relationship between Trn ′ and ΔVr is as shown in FIG. 15 (b).
The differential corresponding clutch torque Trn ′ can be obtained from the difference ΔVr and the ideal left / right wheel rotational speed difference ΔVhr.

In this way, the differential clutch torque Trn ′ obtained from ΔVr and ΔVhr by the differential clutch torque setting section 520 with reference to the map [FIGS. 15A and 15B] is obtained. As shown in FIG.
6 is k ₃ corrected, so that the differential corresponding clutch torque Trn obtained.

In the correction unit 546, the differential compatible clutch torque Trn 'is multiplied by the rear wheel torque gain k ₃ to perform lateral acceleration correction, and the differential compatible clutch torque Trn is obtained. Rear wheel torque gain k
₃ is a rear wheel torque gain setting unit 544, which is set as follows.

That is, to the rear wheel torque gain setting section 544, the rear wheel shared torque Tre as the input torque calculated from the rear wheel shared torque calculation section 560 as the input torque setting means is sent. setting the rear wheel torque gain k ₃ depending on the rear wheel torque distributed Tre from the map shown in the block 544.

The rear wheel torque gain k ₃ is a coefficient to be corrected in accordance with the magnitude of the rear wheel shared torque Tre.
In consideration of the magnitude of e, when the rear wheel shared torque Tre is small, the differential corresponding clutch torque Trn is also reduced, and the differential corresponding clutch torque Trn is also increased according to the increase of the rear wheel shared torque Tre. It is trying to increase.

The rear wheel shared torque Tre is equal to Tre = T
rm, the rear wheel torque gain k ₃ becomes a constant value (k ₃ = 1). Trm is the rear wheel shared torque assuming the maximum acceleration running on a dirt road, and Trm = μ [Wr + ( h / l) · W · Gx] · Rt (1.7) where μ is the road surface friction coefficient, h is the height of the center of gravity, Gx is the longitudinal acceleration of the vehicle, and Rt is the tire radius.

Rear wheel shared torque proportional clutch torque Tra
Is a set torque for preventing an initial slip of the rear wheel when the transmission torque is expected to increase when the vehicle suddenly starts from a stop state, and is set from the rear wheel shared torque Tre. This seeking proportional torque Tra' obtained by k ₄ corrected.

In order to obtain such a rear wheel shared torque proportional clutch torque Tra and thereby control the clutch 414, a rear wheel shared torque calculator 560 and a proportional torque calculator 570 are used as shown in FIG. , and k ₄ correcting unit 572 as a proportional adjustment means, is provided and switch 574a. Note that the proportional torque calculation unit 570 and k
_The differential limiting force setting means is constituted by the _four correction units 572.

As shown in FIG. 7, the rear wheel shared torque calculating section 560 includes an engine torque detecting section 264 for detecting an engine torque Te at a certain moment, and a torque converter torque ratio detecting section 266 for detecting a torque converter torque ratio t at that time. A transmission reduction ratio detection unit 276 for detecting the transmission reduction ratio ρm at that time;
To center differential torque (center differential clutch torque) T
The respective information is sent from the center differential torque setting unit 562 that obtains c, and the rear wheel shared torque Tre is calculated from the engine torque Te, the torque converter torque ratio t, the transmission reduction ratio ρm, and the center differential torque Tc. It is configured to be.

In the engine torque detector 264, the filter 262 sent from the throttle position sensor 38
The throttle opening degree data θth from which the minute vibration component of the data generated by the disturbance or the like is removed through a, and the engine from which the minute vibration component of the data generated by the disturbance or the like is transmitted from the engine speed sensor 170 through the filter 262b and removed. From the rotation speed data Ne, for example, FIG.
The engine torque Te at that time is obtained through the engine torque map as shown in FIG.

In the torque converter torque ratio detecting section 266, the filter 262 b
For example, the transmission torque ratio Ne shown in FIG. 17 is obtained from the engine speed data Ne from which the disturbance component has been removed through the transmission speed sensor N and the transmission speed data Nt sent from the transmission speed sensor 180 and having the disturbance component removed through the filter 262c. The transmission torque ratio t at that time is obtained through a map.

Transmission reduction ratio detecting section 276
Then, based on the selected shift stage information from the shift position sensor 160, a shift stage-reduction ratio correspondence map (not shown)
To determine the transmission reduction ratio ρm.

The center differential torque setting section 562 calculates the center differential torque Tc from the following equation based on the longitudinal acceleration Gx. Tc = (Z / Zr) ・ (Rt / ρrd) [(Wf-Wa ・ Zs / Z) ・ Gx-h / l ・ Wa ・ Gx ² ] ・ ・ ・ (2.1) where Zs is the sun gear tooth Number, Zr is the number of teeth of the ring gear, Wf is the front wheel shared load, Wa is the vehicle weight, ρrd is the final reduction ratio, and Z is Zs + Zr.

The rear wheel shared torque calculating section 560 calculates the rear wheel shared torque Tre based on the engine torque Te, the torque converter torque ratio t, the transmission reduction ratio ρm, and the center differential torque Tc set as described above. This calculation is based on the calculation results Tre ₁ , T
The larger value of re ₂ is adopted.

The arithmetic expression for calculating Tre ₁ is as follows:
This is a torque front-rear distribution formula assuming that the clutch 414 slips. Tre ₁ = (Te · t · ρ ₁ · ρm−Tc) · ρrd · Zr / (Zr + Zs) (2.2)

Further, the calculation formula for calculating Tre ₂ is the following formula, which is a formula assuming that the clutch 414 does not slip, and the rear wheel share torque Tre ₂ obtained by the formula.
Is the rear wheel share torque at rest. Tre ₂ = (Wr / W) · Te · t · ρ ₁ · ρm · ρrd ... ( 2.3 )

[0092] _{Then, Tre = MAX (Tre 1,} Tre 2) than ... (2.4), to determine the rear wheel sharing torque Tre.

[0093] Incidentally, as the rear wheel torque distributed Tre, to adopt a resting rear wheel torque distributed Tre ₂ as described above, the arithmetic expression of Tre ₁ may the value of Tre ₁ becomes negative, thus When the rear wheel is at rest, torque Tre
₂ is adopted. Further, since the clutch control based on the rear wheel shared torque Tre is aimed at starting, the adoption of the stationary rear wheel shared torque Tre ₂ is suitable for this.

The proportional torque calculating section 570 calculates the clutch torque Tra 'proportional to the rear wheel shared torque Tre, and sets the proportional relationship [inclination m (= Tr
a ′ / Tre) is, for example, 0.8], and from Tre to Tr
a ′ is calculated.

The k ₄ correction section 57 as a proportional relation adjusting means
2, the clutch torque Tra thus obtained is
Is multiplied by the rotation difference gain k ₄ to perform correction (proportional relation adjustment). The rotation difference gain k ₄ is set in the rotation difference gain setting section 576 as follows, as shown in FIG.

That is, the rotation difference gain k ₄ is to avoid the tight corner braking phenomenon, and the ideal rotation speed difference ΔVhr set by the ideal rotation speed difference setting section 510 is used.
Are determined according to a map as shown in FIG. The rotation difference gain k ₄ in this map is the ideal rotation speed difference Δ
The relationship with Vhr is expressed by the following equation. K ₄ = 0.9 × (| ΔVhrmax || ΔVhr |) /|ΔVhrmax|+0.1 (2.5) where ΔVhrmax = MAX | ΔVhr (δ = MAX) | and coefficient 0.9 and constant 0 ..1 sets the lower limit of k ₂ to .0.
This is to make it 1.

As described above, the rotation difference gain k decreases linearly as the ideal rotation speed difference ΔVhr increases.
By correcting by ₄ , the ideal rotation speed difference Δ
When Vhr increases, the clutch torque Tra 'is reduced so that turning performance (performance that can prevent the tight corner braking phenomenon) is prioritized over sudden starting performance.

In order to obtain the clutch torque Tra,
The clutch torque Tra is set so as to have a proportional relationship with the ideal rotation speed difference ΔVhr, and the proportional coefficient is determined by the magnitude of the rear wheel shared torque Tre as the magnitude of the rear wheel shared torque Tre is increased. (= Tra / ΔV
hr)] may be provided.

Further, the clutch 574a is connected to the judgment means 5
When the vehicle speed is low (in this example, Vref
<20 km / h), the clutch torque Ta
Is output as data, but when the vehicle speed further increases (Vref ≧ 20 km / h), it is turned off, and a value 0 is output as data of the rear wheel shared torque proportional clutch torque Tra. This is because the rear wheel shared torque proportional control is intended to secure the transmission torque to the road surface by preventing the wheels from slipping. According to the rear wheel shared torque proportional clutch torque Tra, the tight corner braking phenomenon occurs. May occur, or other control speeds may be excluded in situations where slippage is required.To avoid these, a condition has been established in which this rear wheel shared torque proportional control is performed only at a constant vehicle speed. -ing

The clutch torques of the differential corresponding clutch torque Trn and the rear wheel shared torque proportional clutch torque Tra are set for each control cycle repeated at an appropriate timing, and sent to the maximum value selection section 580. The maximum value selection unit 580 selects the maximum clutch torque Trn and Tra (this clutch torque is referred to as Tr ′) for each control cycle. However, when the switch 574a is OFF, 0 is sent as the clutch torque Tra, so the maximum value selection unit 5
At 80, the clutch torque Trn is selected.

[0102] Thus clutch torque Tr' selected in, as shown in FIG. 9, is subjected to k ₅ corrected by k ₅ correcting unit 584. The k ₅ correction, when the traction control is being performed is a correction that reduces the clutch torque Tr ', for example, k ₅ = 0.5, and traction control during traction control (when ON) When it is not (OFF), k ₅ = 1.
It is set to 0.

The clutch torque Tr obtained by the correction in this way is sent to a torque-current conversion section 586, where it is converted into a clutch supply current I such that the set clutch torque Tr is obtained. It has become so. Here, the clutch supply current I is obtained from the clutch torque Tr by using a map (see the block 586 in FIG. 9).

As described above, when the clutch supply current I is obtained, the current limiter (limiter) 588 holds the clutch supply current I at the limit value when the clutch supply current I exceeds the limit value (for example, 3 A). It has become.

Information on the clutch supply current I that has passed through the limiter 588 as described above is taken in by the peak hold filter 590. This peak hold filter 590 is a kind of limiter for preventing an excessive sudden change in the current so that hunting does not occur in the control due to the sudden change in the current. 4 A / s), and a slightly lower limit speed (for example, 5.2 A)
/ S).

When the information of the clutch supply current I is sent such that the speed of the current change exceeds such a limit, the control current according to the limit speed is stopped.

Further, the control current I which has passed through the filter 590 is passed through the switch 592a and then the EMCD coil 42.
0. The switch 592
a, if ABS control (anti-lock brake control) is being performed by a signal from the determination means 592 (O
It is turned off (if N state), and turned on if ABS control is not performed. That is, the signal of the control current I is transmitted on condition that the ABS control is not performed. This is because it is necessary to reliably operate the ABS during the ABS control, and at this time, the torque distribution state of the left and right wheels is controlled because it interferes with the ABS control and is not preferable.

The coil 420 generates a magnetic force in accordance with the control current I sent in this way to adjust the connection state of the clutch 414.

Since this device is configured as described above, differential adjustment is performed as follows.

First, the flow of the entire operation of the drive system is shown in FIG.
As shown in FIG. 9, first, each control element is initially set (step a1), learning of a neutral position of a steering angle (step a2), and learning of preload of a clutch (step a3) are performed. The front and rear wheel driving force distribution control is performed while controlling the clutch 28 in accordance with the duty (step a4), and further, the rear differential is controlled (step a5).

In steps a7 to a11, engine output control (traction control) such as slip control, trace control, torque selection, retard control calculation, and SCI (Serias Communication Interface) communication control is performed, and the torque distribution display lamp is turned on. (Step a
12), a failure diagnosis (failure diagnosis) is performed in step a13. At step a14, a predetermined time (15 mse
c) It is determined whether or not a predetermined time has elapsed (15 mse
c) After a lapse, a runaway check is performed by a watchdog (step a15), and the process returns to step a2 to repeat a series of controls in steps a2 to a13.

That is, the above-described front / rear wheel drive force distribution control, rear differential control, and engine output control are executed at a predetermined cycle (15
msec).

Of these, the control of the rear differential (step a)
5) will be described with reference to the flowcharts of FIGS.

As shown in FIG. 20, first, the wheel speed FR,
FL, RR, RL, rudder angles θ ₁ , θ ₂ , θn, lateral acceleration G
y, longitudinal acceleration Gx, throttle opening θth, engine speed Ne, transmission speed Nt, selected shift stage, and other data are detected, and the driver-requested vehicle speed Vref, driver-requested steering angle δref, etc. are detected from these data. Is calculated (step j1).

Then, an ideal rotational speed difference ΔVhr between the left and right wheels is obtained from the driver required vehicle speed Vref and the driver required steering angle δref according to a map (step j2).
Then, the rotation difference gain k ₄ is set according to the map (step j3).

Further, two kinds of rear wheel shared torques Tre1, Tre1, based on the engine torque Te, the torque converter torque ratio t, the transmission reduction ratio ρm, and the center differential torque Tc.
Tre2 is calculated (steps j4 and j5). And
The larger of the two types of rear wheel shared torques Tre1 and Tre2 is adopted as rear wheel shared torque Tre (step j).
6).

Further, a rear wheel torque gain k ₃ is obtained from the rear wheel shared torque Tre according to a map (step j).
7). Then, a differential corresponding clutch torque Trn from left and right wheel actual rotational speed difference ΔVrd left and right wheels ideal rotational speed difference ΔVhr rear wheel torque gain k ₃ Metropolitan (Step j
8).

[0117] the other hand, the rotational difference gain k ₄ Metropolitan and rear wheel torque distributed Tre, determine the rear wheel allotted torque proportional clutch torque Tra (step j9).

Further, at step j10, the larger one of these clutch torques Trn and Tra is set as the set clutch torque Tr '.

Further, at step j11, the clutch torque Tr ′ determined in this way is applied to the engine output state,
That is, k ₅ corrected by whether the traction control to obtain the clutch torque Tr.

Subsequently, the clutch torque Tr thus corrected and obtained is subjected to torque-current conversion to obtain a clutch supply current I (step j12), and the clutch supply current I is set to a limit value (for example, 3A). ) Is determined (step j13). If I exceeds the limit value, I is held at the limit value (step j14).

Thus, the clutch supply current I subjected to the limiter processing is filtered by the peak hold filter 590 (step j15), and it is determined whether or not ABS control (anti-lock brake control) is being performed (step j16). If the ABS control is performed, the clutch supply current I is set to 0 (step j1).
7) R / D control (rear differential control), that is, differential limiting control through the EMCD coil 420 is performed (step j).
18).

The above-described calculation of the differential corresponding clutch torque Trn is performed as shown in FIG.

First, from the right wheel speed Vrl to the left wheel speed V
The difference ΔVrd (= Vrl−Vrr) obtained by subtracting rr is calculated (step k1), and the difference (actual rotational speed difference between the left and right wheels) ΔVrd is calculated as described above (step j).
3) The difference ΔVr (= ΔVrd−ΔVhr) is obtained by subtracting the obtained ideal rotational speed difference ΔVhr between the left and right wheels (step k2).

Then, in step k3, it is determined whether or not the above-described ideal rotational speed difference ΔVhr of the left and right wheels is 0 or more. If ΔVhr is 0 or more, the process proceeds to step k4, and if ΔVhr is less than 0, the process proceeds to step k5.

When the process proceeds to step k4, the map [FIG.
(A) to obtain the clutch torque Trn from ΔVr.
'Is set.

Specifically, if ΔVr ≧ ΔVhr,
The clutch torque Trn ′ is equal to the difference ΔVr (= ΔVrd−ΔV
Trn ′ = a × (ΔVrd−ΔVhr) = a × ΔVr so as to increase in proportion to the magnitude of (hr) (where a is a proportional constant).

If ΔVhr>ΔVrd> 0,
The clutch torque Trn 'is set to 0 to set a so-called dead zone region.

If 0 ≧ ΔVrd, Trn ′ = − a × ΔVrd = −a × (ΔVr + ΔVh) so that the clutch torque Trn ′ increases in proportion to the magnitude of ΔVrd.
r) (where a is a proportional constant).

When ΔVhr = 0, ΔVhr> Δ
The dead zone region of Vrd> 0 disappears.

When the process proceeds to step k5, the map [FIG.
(Refer to (b)) to calculate the clutch torque Trn from ΔVr.
'Is set.

Specifically, if ΔVrd ≧ 0, Trn ′ = a × ΔVrd = a × (ΔVr + ΔVhr) is set such that the clutch torque Trn ′ increases in proportion to the magnitude of ΔVrd (where a Is a proportional constant).

If 0>ΔVrd> ΔVhr,
The clutch torque Trn 'is set to 0 to set a so-called dead zone region.

Further, if ΔVhr ≧ ΔVrd, the clutch torque Trn ′ becomes ΔVr (ΔVrd−ΔVhr)
Trn ′ = − a × (ΔVrd−ΔVhr) = − a × ΔVr so as to increase in proportion to the magnitude of (where a is a proportional constant).

As described above, the differential corresponding clutch torque Trn 'obtained in steps k4 and k5 is
6 lateral acceleration corresponding corrected by being integrated with the lateral G gain k ₁ in (step k6), differential corresponding clutch torque Tr
n is obtained.

[0135] Such a differential corresponding clutch torque Trn
With this setting, the magnitude of the clutch torque Tr is appropriately set, and while the differential between the left and right wheels is appropriately allowed, the vehicle can behave in accordance with the driver's will during turning.

In particular, the direction SIG of the sensor corresponding steering angle δh
When (δh) is not equal to the direction SIG (Gy) of the lateral acceleration data Gy, the driver-requested steering angle is set to 0, so that, for example, when the driver operates a steering wheel such as a counter steer, etc. Even if the steering position of the steering wheel is different from the actual steering angle (turning state) of the vehicle, inappropriate data is not adopted, which contributes to improvement in control performance.

Further, as the driver request vehicle speed Vref,
Since the second largest wheel speed data from among the rotation speed data signals FL, FR, RL, RR is adopted,
Data reliability is ensured.

As shown in the map (see FIG. 13), the setting of the ideal rotation speed difference ΔVhr increases as the steering angle increases, and increases at low vehicle speeds as the vehicle speed increases. The rear wheels are likely to slip at high speeds, and the responsiveness of the posture of the vehicle body required at higher speeds is ensured. As for the steering angle, the larger the steering angle, the larger the difference in rotation required for the front and rear wheels, and this is appropriately allowed, and there is an advantage that the tight corner braking phenomenon can be avoided.

On the other hand, the calculation of the above-described rear wheel shared torque proportional clutch torque Tra is performed as shown in FIG.

First, the rear wheel shared torque Tre is converted into a clutch torque Tra 'proportional to this (step m).
1), the clutch torque Tra' by the rotation difference gain k ₄
Is corrected to obtain the clutch torque Tra (step m
2).

Further, when the vehicle speed is low (Vref <20 km / h in this example) by the determining means 574, the clutch obtained in step m2 described above is obtained at low vehicle speed (Vref <20km / h). Although the torque Tra is used as a control signal, if the vehicle speed is higher than this (Vref ≧ 20 km /
h), 0 is set as a control signal for the rear wheel shared torque proportional clutch torque Tra.

When the rear wheel sharing torque Tre and the rear wheel sharing torque proportional clutch torque Tra proportional to the ideal rotational speed difference ΔVhr are applied to the left and right wheels at the time of starting or sudden acceleration from a low speed, for example. Differential can be appropriately restricted, and high torque can be transmitted to the road surface as appropriate, preventing tire slip during starting and sudden acceleration, stabilizing running and improving turning performance, etc. The driving performance can be improved at the same time, and the durability of the driving system can be improved.

This rear differential mechanism can be applied to vehicles other than the four-wheel drive vehicle, and can also be applied to the front differential.

[0144]

As described in detail above, according to the vehicle differential limiting control device of the present invention, the differential between the left wheel side drive shaft and the right wheel side drive shaft of the vehicle can be selectively limited. Motion limiting means,
A left wheel side rotation speed detecting means for detecting the rotation speed of the left wheel side drive shaft, and a right wheel side rotation for detecting the rotation speed of the right wheel side drive shaft. The actual rotation speed difference between the left wheel side drive shaft and the right wheel side drive shaft is calculated based on the rotation speeds detected by the speed detection means, the left wheel side rotation speed detection means and the right wheel side rotation speed detection means. An actual rotation speed difference calculating means for calculating and a target rotation speed difference setting means for setting a target rotation speed difference between the left wheel side drive shaft and the right wheel side drive shaft to be generated according to turning of the vehicle are provided. The control means is proportional to the difference between the actual rotation speed difference calculated by the actual rotation speed difference calculation means and the target rotation speed difference set by the target rotation speed difference setting means, The differential limiting force by the motion limiting means A differential limiting force setting means for setting the differential limiting force to be large, and a differential limiting force set by the differential limiting force setting means for the difference between the actual rotation speed difference and the target rotation speed difference. With a configuration including a proportional relationship adjusting means for increasing the rate of increase in force as the input torque to the left wheel side drive shaft or the right wheel side drive shaft increases, such as during start-up or sudden acceleration from a low speed. sometimes,
It becomes possible to appropriately limit the differential between the left and right wheels, and it becomes possible to appropriately transmit a high torque to the road surface, so that the slip of the tire at the time of starting, sudden acceleration or turning acceleration can be more accurately suppressed, At the same time, stable driving and improved turning performance can be achieved, which improves driving performance and contributes to improved drive system durability.

Further, the torque distribution control can be performed more accurately, and the tight corner braking phenomenon can be easily avoided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an overall configuration of a vehicle differential limiting control device as one embodiment of the present invention.

FIG. 2 is an overall configuration diagram of a drive torque transmission system including a differential control device according to the present embodiment.

FIG. 3 is a cross-sectional view showing a rear differential as a left and right wheel differential of the embodiment.

FIGS. 4A and 4B are cross-sectional views taken along the line AA of FIG. 3;

FIG. 5 is a configuration diagram illustrating a rotation speed difference correspondence control unit according to the present embodiment.

FIG. 6 is a configuration diagram illustrating a rear wheel torque gain correction unit according to the embodiment.

FIG. 7 is a configuration diagram illustrating a part of an input torque corresponding control unit according to the present embodiment.

FIG. 8 is a configuration diagram illustrating a part of an input torque corresponding control unit according to the embodiment.

FIG. 9 is a configuration diagram of a portion from a maximum value selection section to a control current output section in the present embodiment.

FIG. 10 is a configuration diagram showing details of a steering angle detection unit of the present embodiment.

FIG. 11 is a configuration diagram illustrating details of a vehicle speed detection unit of the present embodiment.

FIG. 12 is a plan view schematically showing a wheel state for explaining an ideal rotational speed difference of the embodiment.

FIG. 13 is a diagram showing an ideal rotation speed difference setting map according to the present embodiment.

FIG. 14 is a diagram illustrating a rotation difference gain setting map according to the present embodiment.

FIGS. 15 (a) and (b) are diagrams showing differential-corresponding clutch torque setting maps according to the present embodiment.

FIG. 16 is a diagram illustrating an example of an engine torque map according to the present embodiment.

FIG. 17 is a diagram illustrating an example of a transmission torque ratio map according to the present embodiment.

FIG. 18 is a center differential input torque setting map of the present embodiment.

FIG. 19 is a flowchart showing a flow of control of the entire vehicle including the apparatus of the present embodiment.

FIG. 20 is a flowchart illustrating a flow of control of a rear differential according to the present embodiment.

FIG. 21 is a flowchart illustrating a flow of setting a clutch torque corresponding to a rotational speed difference according to the present embodiment.

FIG. 22 is a flowchart illustrating a flow of setting an input torque corresponding clutch torque according to the present embodiment.

[Explanation of symbols]

Reference Signs List 2 engine 4 torque converter 6 automatic transmission 8 output shaft 10 intermediate gear (transfer idler gear) 12 center differential (center differential) 14 differential gear device for front wheel 15 bevel gear mechanism 15A bevel gear shaft 15a bevel gear 16, 18 front wheel 17L, 17R front wheel Side axle 19 Reduction gear mechanism 19a Output gear 20 Propeller shaft 21 Bevel gear mechanism 22 Rear differential (EMCD) as differential gear for rear wheel 23 Differential limiter 24 Left rear wheel 26 Right rear wheel 25L, 25R For rear wheel axle 27 front wheel output shaft 27a hollow shaft member 28 multi-plate clutch 29 rear wheel output shaft 30,30a as differential limiting means, 30b, 30c wheel angle sensor 32 the steering wheel 34, 34a, 34b lateral acceleration sensor 36 Rear acceleration sensor 38 Throttle sensor 39 Engine key switch 40, 42, 44, 46 Wheel speed sensor 48 Controller 48a Rear differential controller 50 Antilock brake device 50A Brake switch 121 Sun gear 122 Planetary pinion (planetary gear) 123 Ring gear 125 Planet carrier 160 Shift lever Position sensor (shift range detecting means) 160A Shift lever of automatic transmission 170 Engine speed sensor 180 Transmission speed sensor 202a-202d Filter 212 Driver required steering angle calculator as steering angle detector (pseudo steering angle calculator) 212a Sensor-based steering angle data setting unit 212b Lateral acceleration data calculation unit 212c Comparison unit (comparing means) 212d Driver-requested steering angle setting unit ( (Vehicle speed data setting unit) 216 driver required vehicle speed calculation unit (pseudo vehicle speed calculation unit) 216a wheel speed selection unit 216c driver required vehicle speed calculation unit 216d filter 218 ideal operating state setting unit Ideal rotation speed difference setting unit 262a, 262b, 262c Filter 264 Engine torque detection unit 266 Torque converter torque ratio detection unit 276 Transmission reduction ratio detection unit 401 Input shaft 402 Drive pinion gear 403 Crown gear 404 Power transmission annular member 405 First housing 406 second housing 407 ring gear 408 sun gear 409 carrier 410a, 410b shaft 411a, the multi-plate clutch 414a as 411b planetary gear 412 bearings 413 case 414 differential limiting means, 41 b clutch disc 415a, 145b holder portion 416 hollow shaft 417 drives 418 the annular support member 419 solenoid as a magnet 420 differential limiting mechanism control means (E
MCD coil) 421 Ball 423 Annular member 424 Groove 425 Chamber 426 Member on second housing side 427 Clutch 428 Bearing 429 Force direction conversion mechanism 430 Electromagnetic clutch mechanism (EMCD) 431 Bolt 500 Left and right wheels as actual rotation speed difference detecting means Actual rotation speed difference detection unit 506 Left and right wheel actual rotation speed difference calculation unit 510 Ideal rotation speed difference setting means (target rotation speed difference setting unit)
Right and left wheel ideal rotation speed difference setting unit 518 as means) Ideal rotation speed difference setting unit 520 as ideal operation state setting unit 520 Differential clutch torque setting unit (differential limiting force setting means) 522 Subtractor 546 Correction unit (k ₃ corrector) after 544 rear wheel torque gain setting unit 560 wheel torque distributed computing unit 562 center differential torque setting unit 570 proportional torque computing section (a part of the differential limiting force setting means) 572 k ₄ correction of the proportional adjustment means part (a part of the differential limiting force setting means) 574 determining unit 574a switches 576 rotation difference gain setting unit 580 maximum value selection unit 584 k ₅ correcting unit 586 torque - current converting unit 588 the current limiting unit (limiter) 590 peak Hol de filter 592 Judging means 592a Switch

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshihito Ito 5-3-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Corporation (56) Reference JP-A-3-86634 (JP, A)

Claims (1)

(57) [Claims] 1. A differential limiting device capable of selectively limiting a differential between a left-wheel driving shaft and a right-wheel driving shaft of a vehicle, and a control device limiting the differential limiting device. Left wheel side rotation speed detection means for detecting the rotation speed of the left wheel side drive shaft, right wheel side rotation speed detection means for detecting the rotation speed of the right wheel side drive shaft, the left wheel side rotation speed detection means and the right wheel An actual rotation speed difference calculating means for calculating an actual rotation speed difference between the left wheel side drive shaft and the right wheel side drive shaft based on each rotation speed detected by the side rotation speed detection means; Target rotation speed difference setting means for setting a target rotation speed difference between the left wheel side drive shaft and the right wheel side drive shaft to be generated by the control means calculated by the actual rotation speed difference calculation means. Difference between the actual rotation speed and the target rotation speed Differential limiting force setting means for setting the differential limiting force so that the differential limiting force by the differential limiting means increases in proportion to the difference from the target rotational speed difference set by the setting means. The increase rate of the differential limiting force set by the differential limiting force setting means with respect to the difference between the actual rotational speed difference and the target rotational speed difference is set to the left wheel side drive shaft or the right wheel side drive shaft. A differential limiting control device for a vehicle, comprising: a proportional relationship adjusting means for increasing the input torque as the input torque increases.