JP3134630B2 - Vehicle yawing momentum control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention calculates a target yawing momentum from an input acting on a vehicle, a physical amount generated in the vehicle, and the like, and calculates a yawing momentum actually generated in the vehicle.
The present invention relates to a yawing momentum control device for a vehicle that performs feedback control so as to match the target yawing momentum. Device, wheel cylinder braking force control device provided on each wheel of the vehicle, stabilizer control device or active suspension device with variable roll stiffness between left and right wheels, and individually controlled steering angle of each wheel The present invention can be applied to a possible four-wheel steering device or the like.

[0002]

2. Description of the Related Art Such a vehicle yawing momentum control device has been developed as, for example, a fastening force control device for a driving force distribution clutch between front and rear wheels or between left and right wheels. JP-A-3-31030 described above. In this drive force distribution clutch engagement force control device, a clutch having a variable engagement force is interposed between the front and rear wheels or between the left and right wheels of the vehicle, and the engine is controlled by controlling the engagement force of the clutch. The drive force transmitted to each wheel can be variably controlled, and the yaw momentum generated in the vehicle can be controlled by controlling the drive force of each wheel.

Here, for example, when performing driving force distribution control between the front and rear wheels of a vehicle, if only the driving force is discussed based on the concept of the friction circle, the driving force applied to each wheel during turning or turning is discussed. As the force increases, the cornering force of the wheel decreases. Therefore, if the driving force to the front wheels during turning is relatively increased with respect to that to the rear wheels, the cornering force of the front wheels is reduced, so that the yawing momentum generated in the vehicle, specifically the yaw rate and The yaw angular acceleration decreases, thereby reducing the yaw moment acting on the vehicle, and the steering characteristics of the vehicle change in the understeer direction. Conversely, if the driving force applied to the front wheels during turning is relatively reduced with respect to that applied to the rear wheels, the cornering force of the front wheels is increased, so that the yaw rate and yaw angular acceleration generated in the vehicle are increased. The momentum increases, the yaw moment acting on the vehicle increases, and the steering characteristics of the vehicle change in the oversteer direction.

Further, for example, when performing driving force distribution control between the rear left and right wheels of a vehicle, if the driving force to the rear wheels as turning outer wheels is increased relatively to that to the rear wheels as turning inner wheels. The yaw moment acting on the vehicle increases, and the yaw rate and the yaw momentum of the yaw angular acceleration generated in the vehicle increase, and the steering characteristics of the vehicle change in the oversteer direction. Conversely, if the driving force to the rear wheel, which is the turning outer wheel, is relatively reduced with respect to that to the rear wheel, which is the turning inner wheel, the yaw moment acting on the vehicle is reduced, and the yaw rate generated in the vehicle is reduced. The yawing momentum of the yaw angular acceleration decreases, and the steering characteristics of the vehicle change in the understeer direction.

[0005] In order to change the steering characteristics of the vehicle by controlling the distribution of the driving force to the respective wheels in this manner, the engagement force control device for the driving force distribution clutch employs the yaw rate and the yaw angular acceleration. It focuses on such yawing momentum, and from such a meaning, it can be handled as a yawing momentum control device. That is, yaw momentum (hereinafter also referred to as actual yaw momentum) such as yaw rate and yaw angular acceleration actually generated in the vehicle can be detected through a sensor such as a yaw moment gyro mounted on the vehicle. On the other hand, the yawing momentum to be achieved by the vehicle as is known (hereinafter referred to as target yawing momentum)
The vehicle speed, the steering angle, or the steering angle can be obtained as variables and can be obtained as a function relating to vehicle characteristics including tire characteristics, specifically, a cornering power, a wheel base, a tread, or a stability factor related to these. The target yawing momentum is also obtained by using the vehicle speed, the steering angle or the turning angle, the yawing momentum and the like as variables, and overshoot and undershoot with respect to the steady yawing momentum obtained as a function related to the vehicle characteristics such as the stability factor. It can be obtained by performing a delay system operation as a temporary delay system without a shoot. Specifically, the target yaw momentum simply increases with an increase in the steering angle or the turning angle under a given vehicle speed. Then, feedback control is performed so that the actual yawing momentum actually generated in the vehicle coincides with the target yawing momentum thus obtained. At this time, in order to realize the target yaw momentum in the actual vehicle, for example, the deviation between the target yaw momentum and the actual yaw momentum is multiplied by a predetermined feedback control gain in consideration of the vehicle specifications and the steering characteristics. I have. The feedback control gain is generally set to a constant value uniquely determined by vehicle specifications and vehicle characteristics. In addition, in the actual driving force distribution clutch engagement force control device, the slip state of the wheels is monitored, and the control force for maintaining the slip ratio in an optimum state is also calculated and controlled.

[0006] Such a yawing momentum control device includes:
For example, Japanese Patent Application Laid-Open No. 60-16125 proposed earlier by the present applicant.
Japanese Patent Application Laid-Open No. H05-A5 (1995) discloses an auxiliary steering control device including a four-wheel steering control device described in Japanese Patent Application Publication No.
193332 discloses an active suspension and stabilizer control device which enables variable roll stiffness control, or Japanese Patent Application Laid-Open No.
Japanese Patent Application Publication No. 24528 discloses a braking force control device for individually controlling the braking force of each wheel of a vehicle.

[0007]

Incidentally, with respect to the tire characteristics of a normal wheel with a pneumatic rubber tire, it is known that the cornering force per unit side slip angle, that is, the cornering power, gradually decreases as the side slip angle increases. I have. This is due to the change in the rate of increase of the cornering force that occurs with an increase in the side slip angle, and while the side slip angle is small, the cornering force increases rapidly and almost linearly with the increase, but eventually the side slip angle increases. When it increases to a certain extent (actually around 6 to 20 °), the rate of increase decreases, and when the skid angle further increases, the cornering force starts to decrease depending on the load on the wheel, that is, depending on the magnitude of the wheel load. It is based on such a phenomenon. Here, it is considered that the increase or decrease of the side slip angle is proportional to the steered angle of the steered wheels, that is, the steering angle.

However, in the conventional yawing momentum control apparatus for a vehicle, the target yawing momentum is regarded as simply increasing, if not linear, with an increase in the steering angle or the turning angle. If
There is a situation in which a change in the cornering power or a change in the increase rate of the cornering force with respect to the increase in the side slip angle accompanying the increase rate of the steering angle or the turning angle is not considered. Therefore, in order to increase the target yawing momentum such as the yaw rate and yaw angular acceleration by obtaining a larger yaw moment, and to follow the actual yawing momentum of the vehicle to increase the turning performance of the vehicle, it is necessary to increase the steering angle. However, in an area where the side slip angle of the front wheels is large and the cornering force is lower than the maximum value, the cornering force of the front wheels, which are steered wheels, is reduced with an increase in the steering angle, and the lateral force of the entire vehicle is also reduced. Therefore, there is a possibility that the traveling line may bulge outward.

For such problems, there is also a yawing momentum control device which takes into consideration the change rate of the cornering power during turning (for example, described in Japanese Patent Application Laid-Open No. H5-242422, which was previously proposed by the present applicant). Braking force control device). However, in such a yawing momentum control device, the cornering power during turning is calculated at any time, and the yawing momentum is feedback-controlled according to the cornering power. A new problem arises in that the time becomes longer. Further, actually, the calculation of the cornering power is not performed in a region where the cornering force is lower than the maximum value, and the above-mentioned problems still exist in this region.

The present invention has been developed in view of these problems, and in a region where the cornering force decreases with an increase in the front wheelslip angle, the steering angle or the turning angle is not particularly increased. However, the target yawing momentum is corrected, and as a result, the corrected target yawing momentum is feedback-controlled to the actual yawing momentum of the vehicle, thereby suppressing a decrease in the lateral force of the front wheels in the relevant region and causing the traveling line to move outward. It is an object of the present invention to provide a yaw momentum control device for a vehicle, which can prevent the swelling of the vehicle.

[0011]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have obtained the following knowledge and developed the present invention. That is, the lateral acceleration generated in the turning state of the vehicle intervenes the vehicle speed, the coefficient of friction between the tire and the road surface, the side slip angle of the tire, the cornering force associated therewith, and the like, so that the actual yawing momentum follows the target momentum. In performing feedback control, we paid attention to the fact that it becomes an evaluation index of vehicle behavior that occurs secondary to steering input. If the driver is familiar with the characteristics of the vehicle, the acceleration operation, specifically, the accelerator operation or the deceleration operation, specifically, the brake operation or the shift operation is performed in a region where the cornering force decreases with an increase in the front wheelslip angle. The down operation attempts to automatically move the vehicle inward without expanding the turning traveling line outward. This is because they are intuitively familiar with the fact that the cornering force is also reduced by the driving force or the braking force applied to each wheel according to the known concept of the friction circle. For example, in a rear-wheel drive vehicle or a vehicle in which the rear wheels are mainly driven wheels, depressing the accelerator reduces the cornering force of the rear wheels relative to that of the front wheels, thereby increasing the yaw moment generated in the vehicle. As a result, the steering characteristics of the vehicle change in the oversteer direction, and as a result, the vehicle cuts inside the turn. Further, in a front-wheel drive vehicle or a vehicle in which the front wheels are mainly driven wheels, the cornering force of the front wheels, which is reduced by stepping on the accelerator, is increased by loosening the accelerator pedal or releasing the accelerator, thereby increasing the front wheels. The so-called tuck-in occurs, in which the grip force is recovered and the vehicle is cut inside the turn. In addition, when the brake is operated while the vehicle is running, the load moves forward of the vehicle due to the inertia of the vehicle. Therefore, the wheel load of the front wheel, which is the steered wheel, increases, and accordingly, the cornering power of the front wheel increases. As a result, the cornering force of the front wheels is increased, and the relative turning performance of the vehicle is improved. Of course, reducing the vehicle speed by performing a brake operation or a shift-down operation before or during the turn is based on the determination that the actual vehicle speed is too fast for the predicted corner size. . Therefore, by detecting these acceleration / deceleration operations or the vehicle longitudinal acceleration generated as a result thereof as the longitudinal acceleration / deceleration state, and correcting the target yaw momentum according to the detected value, the driver's intention and vehicle This can be reflected in feedback control utilizing the turning characteristics.

The yaw momentum control apparatus for a vehicle according to the first aspect of the present invention detects an input acting on the vehicle or a physical quantity generated in the vehicle as shown in a basic configuration diagram of FIG. Input physical quantity detection means, at least acceleration / deceleration of the vehicle in the front-back direction and acceleration /
Front / rear acceleration / deceleration state detecting means for detecting a front / rear acceleration / deceleration state of the vehicle from a deceleration operation amount or the like; steering angle detection means for detecting a steering angle given as a steering input; A yawing momentum detecting means for detecting a yawing momentum actually occurring in the vehicle, and a steering angle detection value detected by at least the steering angle detecting means and a vehicle speed detection value detected by the vehicle speed detecting means. A reference yawing momentum calculating means for calculating a reference yawing momentum as a reference yawing momentum, and a front / rear acceleration / deceleration state detection based on the front / rear acceleration / deceleration state detection value detected by the front / rear acceleration / deceleration state detection means. A correction amount calculating means for calculating a correction amount of the reference yawing momentum which increases with an increase in the value; and a reference yawing momentum calculation Target yawing momentum calculating means for correcting the reference yawing momentum calculated in the step with the correction amount calculated by the correction amount calculating means to calculate a target yawing momentum to be achieved by the vehicle; and the target yawing momentum calculating means And feedback control means for performing feedback control so that the yawing momentum detected by the yawing momentum detecting means coincides with the target yawing momentum calculated in the step (1).

According to a second aspect of the present invention, there is provided a yawing momentum control apparatus for a vehicle, as shown in FIG.
The input physical quantity detection means includes at least a lateral acceleration detection means for detecting a lateral acceleration acting on the vehicle, and the correction amount calculation means includes: It is characterized in that the influence of the correction by the correction amount of the reference yawing momentum in accordance with the detected value of the front / rear acceleration / deceleration state is increased.

[0014]

According to the yaw momentum control device for a vehicle according to the first aspect of the present invention, as shown in the basic configuration diagram of FIG. 1, the yaw momentum detecting means includes a yaw rate sensor and a yaw angular acceleration sensor. The yaw momentum such as the yaw rate and yaw angular acceleration actually generated is detected. On the other hand, the steering angle detecting means detects a steering angle via, for example, a steering angle sensor or the like, the vehicle speed detecting means detects a vehicle front-rear vehicle speed via, for example, a vehicle speed sensor, and the reference yawing momentum calculating means. ,
Using these steering angle detection values and vehicle speed detection values, a reference yawing momentum such as a reference yaw rate and a reference yaw angular acceleration is calculated and set by a predetermined arithmetic expression, map search, or the like. Further, in the front / rear acceleration / deceleration state detecting means,
For example, a throttle opening degree related to an accelerator operation, a brake pedal depression amount related to a brake operation, a brake fluid pressure, or the like is detected as a driver's acceleration / deceleration operation amount. The acceleration / deceleration state is detected as an input physical quantity by detecting the acceleration / deceleration state by an acceleration sensor or the like, and the correction amount calculating means determines the reference acceleration / deceleration state by a predetermined arithmetic expression or map search according to the detected value of the acceleration / deceleration state. A correction amount for the yawing momentum is calculated and set. The target yawing momentum calculating means corrects the correction amount calculated and set by the correction amount calculating means with respect to the reference yawing momentum calculated and set by the reference yawing momentum calculating means to calculate and set the target yawing momentum. I do. In performing the feedback control so that the yaw momentum (actual yaw momentum) detected by the vehicle follows the target yaw momentum calculated in this way, the feedback control means may determine a difference between the two yaw momentums, for example. And the actuator applied to the vehicle is driven such that the deviation between the two yaw momentums multiplied by the feedback control gain becomes a predetermined value, for example, zero. Here, in the present invention, the target yawing momentum is calculated and set by correcting a correction amount corresponding to the front / rear acceleration / deceleration state detection value with respect to the reference yawing momentum calculated and set only from the vehicle speed detection value and the steering angle detection value. . At this time, for example, as described above, in a rear-wheel drive vehicle or a vehicle in which the rear wheel mainly serves as a drive wheel, depressing an accelerator pedal at the beginning of a turn or during a turn means that the cornering force of the rear wheel is a front wheel. In this case, the driver intends to change the steering characteristic of the vehicle in the oversteer direction to cut the vehicle inside the turning direction. The throttle opening is detected, or the resulting acceleration (also referred to as positive acceleration) of the vehicle is detected, and the target yawing momentum is set to the reference yawing momentum in accordance with the increase in the absolute value of the front-back acceleration / deceleration state detection value. The correction amount may be calculated and set so that the yaw moment of the vehicle is set to be larger than the yaw moment. It is long in it is possible to Kirekoma inside without bulging the traveling line of the vehicle in the turning outer side. Further, in a front-wheel drive vehicle or a vehicle in which the front wheels are mainly driven wheels, loosening the accelerator pedal or opening the accelerator during the initial turn or during the turn can reduce the cornering force of the drive front wheels, which is reduced by the driving force. Since the driver's intention is to suppress the vehicle to the inside of the turn by suppressing it, in such a case, according to the decrease in the absolute value of the front-back acceleration / deceleration state detection value detected in the same manner as described above. The correction amount may be calculated and set so that the target yawing momentum is set to be larger than the reference yawing momentum. In this way, the yaw moment of the vehicle is promoted, and the traveling line of the vehicle expands outward. It is possible to cut it inside without any trouble. Also, performing the brake operation during traveling increases the wheel load of the front wheels, which are steered wheels, due to the inertia of the vehicle, thereby increasing the cornering power of the front wheels, and consequently increasing the cornering force of the front wheels, thereby turning the vehicle. In such a case, the amount of depression of the brake pedal and the brake fluid pressure due to the brake operation are detected, or as a result of the shift-down operation performed together therewith, as a result, the driver intends to improve the vehicle performance. The target yawing momentum is set to be larger than the reference yawing momentum in accordance with the increase in the absolute value of the detected value of the front / rear acceleration / deceleration state. The yaw moment of the vehicle is promoted by doing so, so that the running line of the vehicle is out of turning. It is possible to Kirekoma inside without bulging thing. Needless to say, the case where the brake operation or the downshift operation and the situation where negative acceleration is generated in the vehicle due to the brake operation or the downshift operation is due to the determination that the actual vehicle speed is too fast with respect to the predicted corner size. In addition, since the turning performance of the vehicle is improved, it becomes possible to cut the traveling line of the vehicle inward without expanding to the outside in the same manner as described above. in this way,
According to the yaw momentum control device for a vehicle of the present invention, the driver familiar with the vehicle characteristics can perform acceleration / deceleration operations and acceleration / deceleration operations performed in a region where the cornering force decreases with an increase in the front wheelslip angle without increasing the steering angle. Since the vehicle can be cut into the inside of the turn with the resulting acceleration / deceleration, the steering angle is increased as in the related art, and the front wheels, which are steered wheels, are further cut and increased as in the related art. Further, it is possible to prevent the cornering force from decreasing and the turning traveling line from expanding outward.

In the yaw momentum control apparatus for a vehicle according to a second aspect of the present invention, as shown in the basic configuration diagram of FIG. 1, the lateral acceleration detecting means uses a lateral acceleration sensor or the like to apply a lateral acceleration to the vehicle. The correction amount calculation means detects the influence of the correction by the correction amount of the reference yawing momentum according to the detected value of the front / rear acceleration / deceleration state according to the increase of the detected lateral acceleration value detected by the lateral acceleration detection means. To increase. Here, the detected value of the lateral acceleration detected by the lateral acceleration detecting means is an increasing function using a cornering force that changes in accordance with an increase in the steering angle corresponding to the side slip angle, particularly, in the case of the front wheel, the steering angle. Therefore, the cornering force can be estimated based on the magnitude of the lateral acceleration detection value.Accordingly, in the region where the rate of increase of the cornering force decreases and the region where the cornering force further decreases, the cornering force can be estimated according to the front-rear acceleration / deceleration state detection value. By increasing the influence of the corrected amount, the improvement effect on the vehicle turning traveling line can be clearly exhibited. Conversely, if the target yawing momentum is significantly corrected by the longitudinal acceleration / deceleration state detection value in a region where the cornering force is simply increasing with an increase in the side slip angle, the driver accelerates / decelerates the longitudinal acceleration / deceleration. It is not preferable because it is necessary to control the two operation amounts of the operation and the steering angle operation.However, if the influence of the correction based on the front / rear acceleration / deceleration state detection value is increased in accordance with the increase in the lateral acceleration detection value, the reverse is obtained. In the region where the detected value of the lateral acceleration is small, that is, in the region where there is a margin in the cornering force, the influence of the correction based on the detected value of the front / rear acceleration / deceleration state is small, and the driver simply controls almost only the steering angle to obtain the target yaw momentum. Since the actual yawing momentum may be controlled to follow, it is possible to avoid a decrease in the maneuverability of the vehicle.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a yaw momentum control device for a vehicle according to the present invention will be described below with reference to the accompanying drawings. 2 to 13 show a first embodiment in which the yaw momentum control device for a vehicle according to the present invention is applied to a drive force distribution control device between front and rear wheels. In this embodiment, a case will be described in which the present invention is applied to a transfer clutch of a driving force distribution control device for a four-wheel drive vehicle based on an FR (front engine / rear drive) system.

In FIG. 2, reference numeral 1 denotes a rotary drive source, that is, an engine as an engine; 2FL to 2RR, front left wheels to rear right wheels;
Reference numeral 4 denotes a driving force distribution control device that can change and control the driving force distribution ratio to the wheels 2FL to 2RR, and 4 denotes a driving force distribution control device that controls driving force distribution by the driving force transmission system 3. The driving force transmission system 3 includes a clutch (not shown) for intermittently driving the driving force from the engine 1, a transmission 12 for shifting the output of the clutch at a selected gear ratio, and a driving force from the transmission 12 for the front wheels. 2FL, 2FR side and rear wheel (normal drive wheel) 2R
And a transfer 14 for dividing into L and 2RR. In the driving force transmission system 3, the transfer 1
The front wheel side driving force divided by 4 is transmitted to the front wheels 2FL and 2FR via the front wheel side output shaft 16, the front differential gear 18, and the front wheel side drive shaft 20. On the other hand, the rear wheels 2RL, 2RR are driven via a propeller shaft (rear wheel output shaft) 22, a rear differential gear 24 and a rear wheel drive shaft 26.
Is transmitted to

In the transfer 14, as shown in FIG. 3, the left end of the input shaft 30 inserted into the transfer case 28 is connected to the output side of the transmission 12.
The input shaft 30 is rotatably supported by bearings 31 and the like. The right end of the input shaft 30 in FIG. 3 is connected to an output shaft 33 rotatably supported by a bearing 32, and the output shaft 33 is connected to the propeller shaft 22. The detailed structure of this transfer and a transfer clutch described later is described in, for example, Japanese Patent Application Laid-Open No. 1-2048, which was previously proposed by the present applicant.
See No. 26 publication.

On the other hand, at the center of the input shaft 30, there is provided a fluid type multi-plate clutch mechanism 37 as a variable torque clutch capable of changing the torque distribution ratio to the front and rear wheels. The clutch mechanism 37 includes a clutch drum 37a spline-coupled to the input shaft 30, a friction plate 37b rotationally engaged with the clutch drum 37a, and a needle bearing or the like on the outer peripheral portion of the input shaft 30. A freely rotatable clutch hub 37c
And a friction disc 37d rotationally engaged with the clutch hub 37c.
A clutch piston 37e arranged on the right side of
There is a cylinder chamber 37f formed between the clutch piston 37e and the clutch drum 37a. In the clutch mechanism 37, 37h is a return spring for the clutch piston plate 37e. The clutch mechanism 37 is also connected to the front wheel side via a gear train mounted on the left end side in FIG. 3 as shown. That is, the clutch hub 37c
Is spline-coupled to the first gear 41a.
Gear 41a is meshed with a second gear 41b rotatable by bearings 40a and 40b, and the second gear 41b is connected to the front wheel side via the third gear 41c rotatable by bearings 42 and 43. It is connected to the output shaft 16.

At a predetermined position on the side surface of the transfer case 28, there is formed an input port through which a hydraulic pressure from a pressure control valve 66 constituting a part of a clutch control device described later is supplied as a command force. The working oil pressure is supplied from the input port to the cylinder chamber 37f. For this reason, in a state in which the operating oil pressure is not supplied to the input port, that is, in a state in which the pressure in the cylinder chamber 37f of the clutch mechanism 37 is the atmospheric pressure or substantially equal to the atmospheric pressure, the elastic force of the return spring 37h causes the friction plate 37b to be in contact with the friction plate 37b. The friction disk 37d is separated. Therefore, in this state, all of the input torque transmitted to the input shaft 30 is transmitted to the rear wheels via the output shaft 33 and the propeller shaft 22, and a two-wheel drive state with only the rear wheels is established. On the other hand, when the operating oil pressure is supplied to the input port, a pressing force is generated by the clutch piston 37e according to the degree of pressurization of the cylinder chamber 37f, and the pressing force is generated between the friction plate 37b and the friction disk 37d. A portion of the total drive torque is also transmitted to the front wheels via the output shaft 16. The transmission torque ΔT to the front wheels is given by the following equation with respect to the supplied working oil pressure P, and increases linearly with respect to the supplied working oil pressure P as shown in FIG.

[0021] ΔT = P · S · 2n · μ · r m ......... (1) where, S is the pressure acting area of the piston 37e, n is friction Disc, mu is the friction coefficient of the clutch plate, r
_m is the torque transmission effective radius of the friction disk. That is, the transmission torque ΔT to the front wheels is proportional to the supply oil pressure P, and eventually the drive torque is distributed and transmitted to the rear wheels and the front wheels according to the fastening force. The distribution ratio of the torque to the front and rear wheels can be continuously changed (from 0: 100 to 50:50) according to the pressure P of the hydraulic oil supplied to the input port.

Returning to FIG. 2, on the other hand, the driving force distribution control device 4 includes the transfer 14, the fluid pressure source 35 for pressurizing and supplying the hydraulic oil in the reservoir 35b, and the hydraulic pressure supplied from the fluid pressure source 35. The pressure control valve 50 for variably controlling the oil supply to the input port of the fluid type multi-plate clutch mechanism 37, the front wheel side rotation sensor 54 and the rear wheel side rotation sensor 56, and detecting the lateral acceleration acting on the vehicle body A lateral acceleration sensor 51, a vehicle speed sensor 52 for detecting the vehicle speed in the front-rear direction of the vehicle, a steering angle sensor 53 for detecting a steering angle of a steering wheel (not shown), and a yaw rate actually generated in the vehicle as yaw momentum. A yaw rate sensor 55, a longitudinal acceleration sensor 49 for detecting the longitudinal acceleration of the vehicle, and a throttle for detecting the throttle opening by operating the accelerator. A torque opening sensor 48, comprising a controller 58 for controlling the output pressure of the pressure control valve 50 based on the detection signals from these sensors.

The fluid pressure source 35 is driven to rotate by an electric motor 35a as shown in FIG.
b) an oil pump 35c which boosts the hydraulic oil in b and supplies it to the input port of the clutch mechanism 37, a check valve 35d interposed on the discharge side of the oil pump 35c, the check valve 35d and the input An accumulator 35e connected to the conduit between the ports, and the accumulator 35e
And a relief valve 35k connected to the connection point of the accumulator 35e.
The pressure control valve 50 is connected between the input ports.

Here, the electric motor 35a has one end of its exciting winding connected to a positive battery power source B via a motor relay 35h and the other end grounded.
h is a pressure switch 35 which operates by detecting the line pressure of the line between the accumulator 35e and the pressure control valve 50.
Drive control is performed based on the detected value of i. That is, the base of the transistor 35j constituting the switching regulator through a resistor R ₁ and the pressure switch 35i is connected to the positive battery source B, a collector connected to the positive battery power source B via a relay coil of Motarire 35h, Since the emitter is grounded, the accumulator 35
When the line pressure of the line between the pressure control valve 50 and the pressure control valve 50 is equal to or higher than a predetermined set pressure, the pressure switch 35i is turned off, the switching transistor 35j is also turned off, and the normally open contact t of the motor relay 35h is opened to operate the motor. The motor 35a is de-energized, the electric motor 35a is stopped in response to this, and the hydraulic oil pressure equal to or higher than a predetermined set pressure as the line pressure is applied to the relief valve 35.
k is relieved. On the other hand, accumulator 3
When the line pressure of the line between the pressure control valve 5e and the pressure control valve 50 is lower than a predetermined set pressure, the pressure switch 35i is turned on, and the switching transistor 35j is accordingly turned on.
Is turned on, the motor relay 35h is urged, the normally open contact t is closed, and the electric motor 35a is driven to rotate, whereby the line pressure of the pipeline is increased by the oil pump 35c. Thus, the present fluid pressure source 3
From 5, almost stable working oil pressure is supplied toward the primary side of the pressure control valve 50.

The pressure control valve 50 is a so-called electromagnetic proportional control.
Type pressure reducing valve.
Drain port of pressure control valve 50 and tank 6
2 is provided with a drain pipe 63. This pressure
The control valve 50 is supplied to its proportional solenoid 50a
Command current I_SOLIs disposed in the pressure reducing valve in accordance with the value of
The degree of opening of the spool is determined, and as a result, the secondary side of the pressure reducing valve,
That is, the control pressure P on the clutch mechanism 37 side_CIs the primary side,
Irrespective of pressure fluctuation to the input port of the pressure reducing valve,
Current I_SOLIs maintained at the set pressure corresponding to After all, crack
The pressure P of the hydraulic oil supplied to the input port of the
As shown in FIG._SOLQuadratic curve in proportion to
Simply increase. Note that this pressure control
Electromagnetic proportional control type secondary pressure constant type pressure reduction used for the valve 50
For the specific structure of the valve, for example, the applicant has previously proposed
Japanese Patent Application Laid-Open No. 2-68225.
I want to be illuminated. Also, in this embodiment, when the vehicle is traveling straight ahead at a constant speed.
Transmission torque ΔT to the front wheel side is neutral torque ΔT_NAs
The driving force distribution ratio of the front and rear wheels in this state is about 2
5:75, this neutral torque Δ
T_NInput port of the pressure control valve 50 to achieve
Supply pressure P to neutral pressure P_NAnd this neutral pressure P _NAchieve
Command current I_SOLIs the neutral command current I_NAnd

On the other hand, the front wheel side rotation sensor 54 and the rear wheel side rotation sensor 56 are individually provided at predetermined positions of the front wheel side output shaft 16 and the rear wheel side propeller shaft 22,
The number of rotations of each shaft is detected by an optical method or an electromagnetic method, and the front and rear wheel rotation detection values nF and nR based on a pulse signal or a sine wave signal corresponding thereto are individually output to the controller 58. Further, the lateral acceleration sensor 51
Outputs to the controller 58 a lateral acceleration detection value Yg which is a voltage proportional to the magnitude of the centrifugal acceleration acting on the vehicle body. The vehicle speed sensor 52 outputs to the controller 58 a vehicle speed detection value V including a voltage output that increases in the positive direction according to the vehicle speed in front of the vehicle. Further, the steering angle sensor 53 outputs a steering angle detection value θ including a voltage output corresponding to the steering angle of the steering wheel to the controller 58. Further, the yaw rate sensor 55 outputs an actual yaw rate detection value ψ ′ composed of a voltage proportional to the actual yaw rate actually generated in the vehicle to the controller 58. The detection signals corresponding to the respective detection values of these sensors are positive values proportional to the magnitude of the absolute value of the input physical quantity to be detected, regardless of the width direction of the vehicle.

The longitudinal acceleration sensor 49 is for detecting an acceleration / deceleration acting in the longitudinal direction of the vehicle, and is specifically a vehicle which is positive with respect to a positive acceleration acting in the forward direction of the vehicle. The acceleration / deceleration detection value Xg, which is negative with respect to the negative acceleration (deceleration) acting in the backward direction and is composed of a voltage output corresponding to the magnitude of the acceleration in each direction, is output to the controller 58. The throttle opening sensor 48 is constituted by a positioner or the like for detecting a throttle opening obtained as an accelerator operation amount. Specifically, when the accelerator operation amount is "0", that is, when the accelerator pedal is operated, The throttle output when the accelerator pedal is not depressed is set to 0%, and the throttle opening when the accelerator pedal is depressed to the limit is set to 100%. The throttle opening detection value Acc is stored in the controller 58.
Output to

The controller 58 includes a microcomputer.
Data 70 and the command current I_SOLPressure control valve 5
And a driving circuit 59 for driving the zero. Also my
The microcomputer 70 receives the detection signals from the sensors.
An input with an A / D conversion function for reading as each detection value
Force interface circuit 70a and arithmetic processing unit 70b
And a storage device 70c such as a ROM or a RAM.
Clutch control signal S obtained by controller 70b_TTo
Output interface having D / A conversion function for outputting
Source circuit 70d. This controller 58
The microcomputer 70 of FIG.
And the front and rear wheel rotation detection values nF, nR
To the predetermined first control gain K₁Multiplied by
And calculates the clutch torque TN of the
The reference yaw based on the detected steering angle θ and the detected vehicle speed V
Rate ψ^'* ₀Is calculated based on the lateral acceleration detection value Yg.
And the throttle opening correction coefficient Ka and the longitudinal acceleration correction
A number Kb is calculated and set, and the throttle opening detection value Acc is calculated.
And the first target yaw based on the throttle opening correction coefficient Ka.
-Rate correction coefficient K₁Calculate and set
Based on the output value Xg and the longitudinal acceleration correction coefficient Kb.
2 Target yaw rate correction coefficient K_TwoCalculate and set
When the acceleration detection value Xg is positive, it is determined that the vehicle is accelerating.
The reference yaw rate.^'* ₀The first target yaw rate
Correction coefficient K₁And the target yaw rate ヨ ー ^'*Is calculated, and
If the rear acceleration detection value Xg is not positive, it is not accelerating.
And the reference yaw rate ψ^'* ₀The second target Yawley
G correction coefficient K_TwoAnd the target yaw rate ヨ ー^'*Is calculated,
This target yaw rate ψ^'*And actual yaw rate detection value ψ^'With
Yaw rate deviation Δψ^'And the goals obtained by differentiating them
Yaw angular accelerationψ^"*And actual yaw angular acceleration ψ^"Yaw angle acceleration with
Degree deviation Δψ^"And the yaw angular acceleration deviation Δ 加速度 ^"To
The third control gain K set in advance_ThreeMultiplied by
-Rate deviation Δψ^'And add
Second control gain K_TwoMultiplied by
Luc Tψ^'Is calculated and the clutch torque corresponding to the yaw rate is calculated.
Ku Tψ^'And the clutch torque TN, and
The clutch engagement force T is calculated and the clutch engagement force T is achieved.
Control signal S_TIs output to the drive circuit 59.

[0029] The drive circuit 59 is to convert the control signal S _T output from the microcomputer 70 to the command current I _SOL is a drive signal to the proportional solenoid 50a of the pressure control valve 50, for example, a floating type It is composed of a constant voltage circuit and the like. The driving circuit 5
9, when the control signal _ST is zero, the command current I
_SOL The converted such that the neutral command current I _N outputs.

Next, the basic principle of the arithmetic processing performed in the controller of this embodiment will be described. First, in the above-described four-wheel drive vehicle based on FR, it is known from the concept of the friction circle that the cornering force is reduced when a driving force is applied as a tire characteristic. It is not clear whether the reason for this is that the cornering force is reduced due to the turning of the steering wheel or that the friction coefficient μ of the road surface is simply reduced. For example, during turning, the rear wheels slip due to a decrease in the cornering force due to the driving force, and as a result, the yaw rate increases in a situation where the steering characteristics of the vehicle change in the oversteer direction. Conversely, during turning, the front wheels slip due to a decrease in cornering force due to the driving force, and as a result, the yaw rate decreases in a situation where the steering characteristics of the vehicle change in the understeer direction.

As described above, the clutch mechanism 37 provided in the transfer 14 controls the distribution of the driving force between the front and rear wheels, and the above problem can be solved by controlling the distribution of the driving force to the front and rear wheels. The clutch torque of the clutch mechanism may be obtained by multiplying a value obtained by subtracting the rotation speed nF of the front wheels from the rotation speed nR of the rear wheels by an appropriate control gain according to the lateral acceleration. That is, when the rear wheels are slipping due to the driving force, the driving force distribution to the front wheels may be increased to relatively reduce the driving force of the rear wheels. The clutch torque of the clutch mechanism is increased based on the value obtained by reducing the rotational speed nF of the motor, and the driving force transmission rate to the front wheels is increased, whereby the driving force of the front wheels is increased. As described above, in the present embodiment, the driving force distribution control to the front wheels is performed based on the front-rear wheel rotation difference ΔN only when the rear wheels that are the driving wheels slip. Note that when slippage occurs in the front wheels, the driving force distribution ratio is not changed and controlled.

Specifically, the deviation of the rotational speed between the front and rear wheels, that is, the front and rear wheel rotation difference ΔN is obtained according to the following two equations. ΔN = nR−nF (2) On the other hand, the first control gain K ₁ multiplied by the deviation ΔN of the rotational speed between the front and rear wheels is obtained by the following three equations using a function f ₁ for the lateral acceleration Yg. .

K₁= F₁(Yg) (3) Specifically, the first control gain K₁Increases lateral acceleration
Accordingly, 0 ≦ Yg <Y ₁At the time of K₁= Ka, Y₁≤Y
g <Y_TwoAt the time of K₁= Kb, Y_TwoK when ≤Yg₁
= Kc (where 0 <Y₁<Y_Two, Ka> Kb> Kc)
Or K₁= A / Yg (A: constant
Number).

By multiplying the first control gain K ₁ thus set by the front and rear wheel rotation difference ΔN,
The clutch torque TN based on the front-rear wheel rotation difference ΔN is obtained. The transmission clutch torque TN to the front wheels based on the front-rear wheel rotation difference ΔN can be obtained in accordance with a control map as shown in FIG. 6, which directly shows the correlation with the front-rear wheel rotation difference ΔN.

Next, the principle of performing feedback control to follow the actual yawing momentum actually generated in the vehicle to the target yawing momentum obtained from the input acting on the vehicle or the physical amount generated in the vehicle will be described. First,
Before the target yaw rate ψ ^'* and the target yaw angular acceleration ψ ^"* set as the target yaw momentum, two methods of calculating the reference yaw rate ψ ^{' *} ₀ as the reference yaw momentum will be described.

First, as described above, the reference yaw rate ψ ^{′ *} ₀ is obtained by using the vehicle speed V and the steering angle θ as variables according to _the known vehicle motion equation, and using the vehicle specifications as coefficients as follows.
Given by the formula. ψ ^'* = V / R R = K _S L / tan (θ / N) (4) where R: turning radius, L: wheel base, N: steering gear ratio. K _S is a stability factor, and this stability factor K _S is a coefficient indicating the stability of vehicle behavior appearing in turning characteristics and the like. Generally, as the stability factor K _S increases, the steering characteristic tends to understeer. Is done.

The reference yaw rate ψ ^{′ *} ₀ can also be calculated using the steady yaw rate H ₀ . In general, the steady yaw rate H ₀ is calculated by using the vehicle speed V and the steering angle θ as variables and using the stability factor K _S , the steering gear ratio N and the wheel base L as coefficients.
Given by the formula. H ₀ = V / (L · (1 + K _S V ² )) · (θ / N) (5) And the reference yaw rate ψ ^{′ *} ₀ is the steady yaw rate H
₀ is also known to be obtained by performing the first-order lag system operation using the time constant τ primary delay according to the following 6 formulas respect.

Ψ ^{′ *} ₀ = H ₀ / (1 + τs) (6) where s represents a Laplace operator (Laplacian). Here, it is of course possible to calculate the reference yaw rate ψ ^{′ *} ₀ in accordance with the above-mentioned equation (4), (5) and (6), but it is difficult to avoid that the load involved in the calculation becomes considerable. Therefore, in the present embodiment, the correlation between the steering angle detection value θ, which is the steering input according to these calculation formulas, and the reference yaw rate ψ ^* ₀ is shown in the control map of FIG. 8 using the vehicle speed detection value V as a parameter. The control map is linearly interpolated in accordance with the read vehicle speed detection value V to calculate and set the reference yaw rate ψ ^{′ *} ₀ . According to this, it is possible to reduce at least the calculation load related to the complicated calculation of each calculation formula, and to shorten the processing time.

Conventionally, the reference yaw rate ψ ^{′ *} ₀ is directly or almost directly used as the target yaw rate, that is, the target yawing momentum, but the disadvantages related to this are as described above. On the other hand, as described above, in the tire characteristics of a general wheel with a pneumatic rubber tire, as shown in FIG. 9, the cornering force C _F once increases almost linearly with an increase in the side slip angle SA, but eventually increases. The rate tends to decrease and tends to decrease from a certain value depending on the wheel load. Then, the driver familiar with the vehicle characteristics and tire characteristics, the rate of increase in cornering force C _F for this way slip angle SA, namely reduction and cornering power, steering wheel in the region where the reduction in the cornering force C _F itself is generated Even if the steering angle is increased, the control effect is small, and therefore, the vehicle behavior during turning is controlled by the acceleration operation or the deceleration operation. That is, in this embodiment, the reference yaw rate ψ ^'*
_In calculating the target yaw momentum for ₀ ,
The driver's operation intention is found by the acceleration operation or deceleration operation performed in the area where the cornering power is reduced or the area where the cornering force itself is reduced, or the longitudinal acceleration / deceleration generated in the vehicle as a result of the operation. It is intended to stabilize the vehicle behavior by reflecting the momentum. Here, ^'calculated set as the correction rate K to be multiplied to ^* _0, the correction rate K reference yaw rate ^[psi' a correction amount in accordance with these operations making the reference yaw rate [psi the target yaw rate [psi ^'* by multiplying the ^* ₀ calculate.

Now, in the four-wheel drive vehicle in which the rear wheels are the main drive wheels as in the present embodiment, the depression of the accelerator pedal which appears as an acceleration operation, that is, the increase in the detected throttle opening is caused by the friction circle. According to the concept, the cornering force of the rear wheel, which is the main driving wheel, is consciously lowered as compared with that of the front wheel, and the turning characteristic of the vehicle in the oversteer direction is used to make the vehicle turn inside. It is understood that they try to cut into. Here, as described above, the area where the cornering force C _F has a margin, that is, the cornering force C _F is the side slip angle S _F.
The accelerator pedal operation amount, that is, the driver's acceleration operation amount, is a region in which the vehicle can be increased substantially linearly with the increase of A, that is, a region in which the lateral force acting on the vehicle can be linearly increased by increasing the steering angle. Has a great influence on the correction of the target yaw momentum, the driver's sensation must also control the steering angle, and at the same time must also control the amount of depression of the accelerator pedal. Not preferred. Therefore, it is desired that the influence of the correction of the target yawing momentum according to the acceleration operation or the resulting acceleration be increased only in the region where the cornering power decreases from the region where the cornering power decreases.

Here, as described above, the lateral acceleration sensor 51
Paying attention to the lateral acceleration detection value Yg detected in the above, it can be understood that the lateral acceleration detection value Yg is generated (obtained) by the cornering force C _F that increases with the increase in the side slip angle SA. A throttle opening correction coefficient Ka that increases as the lateral acceleration detection value Yg increases is set, and the throttle opening correction coefficient Ka is multiplied by the throttle opening detection value Acc to obtain a target yaw rate correction coefficient during acceleration, Here, the first target yaw rate correction coefficient Kα may be set. FIG. 10 is a control map of the correlation between the detected lateral acceleration value Yg and the throttle opening correction coefficient Ka. Here, examples of areas where cornering force C _F increases almost linearly with increasing slip angle SA, the detected lateral acceleration detected value Yg throttle opening correction in the region of the first predetermined value Yg ₁₁ 0 to The coefficient Ka is kept at "0" to prevent the target yaw rate from being corrected by the accelerator operation, and the lateral acceleration detection value Yg is set as an area where the cornering power gradually decreases and the cornering force eventually decreases.
Is an area from the first predetermined value Yg ₁₁ to the second predetermined value Yg ₁₂ ,
The throttle opening correction coefficient Ka is calculated as a lateral acceleration detection value Y
with increasing g increases gradually at a gradient of a first lateral acceleration correction coefficient Ka ', the predetermined value Ka ₁ a throttle opening correction coefficient Ka is detected lateral acceleration Yg is at the second predetermined value Yg ₁₂ more regions To hold. This lateral acceleration detection value Yg is the second
At the predetermined value Yg ₁₂ or more regions, it is assumed that changes in the large oversteer direction of the steering characteristic of the vehicle.
In such a situation where a large oversteer change occurs, the detected lateral acceleration detection value Yg also becomes a large value. In this situation, however, the first target yaw rate correction coefficient Kα becomes excessively large according to the throttle opening detection value Acc. Is set to
The yaw moment acting on the vehicle becomes larger and the oversteer change is promoted, and the vehicle behavior becomes unstable. Therefore, the first target yaw rate correction coefficient K
Since α is not set to be excessive, the lateral acceleration detection value Y
g is in the second predetermined value Yg ₁₂ more regions to hold the throttle opening degree correction coefficient Ka to a predetermined value Ka ₁ is an upper limit value.
The first lateral acceleration correction coefficient Ka 'is calculated backward from each of the predetermined values. The inclination and the first lateral acceleration correction coefficient Ka need not always be constant values.

Using the throttle opening degree correction coefficient Ka thus set, the first target yaw rate correction coefficient Kα
Is set according to the throttle opening detection value Acc according to the control map shown in FIG. Here, as the dead zone subtle speed adjustments zone, in the area of the throttle opening detection value Acc is 0 first predetermined value Acc _1, the accelerator operation while holding the "1" to the first target yaw rate correction coefficient Kα Is not executed, and the throttle opening detection value Acc is changed to the first predetermined value Acc _1.
In areas ~ certain value Acc _2, with a slope to increase the throttle opening correction coefficient Ka and then and throttle opening detection value Acc set in the control map of FIG. 10, a predetermined first target yaw rate correction coefficient Kα gradually increased to a value K [alpha _1, the first target yaw rate correction coefficient K [alpha is a predetermined value K [alpha
A certain value Acc ₂ of the throttle opening detection value Acc that becomes ₁
In the above region, holding the first target yaw rate correction coefficient K [alpha to a predetermined value K [alpha _1. Note that the predetermined value Kα ₁ is the first
The upper limit value of the target yaw rate correction coefficient Kα. For example, when the target yaw rate ψ ^{′ *} is calculated by multiplying the reference yaw rate ψ ^{′ *} ₀ by using the first target yaw rate correction coefficient Kα as a correction ratio K, the correction is performed. If the first target yaw rate correction coefficient Kα, which is the ratio K, is too large, the target yaw rate ψ ^{′ *} is set too large with respect to the actual yaw rate ψ ^′. As a result, a large yaw moment is generated in the vehicle, and the vehicle behavior is reduced. because there is a possibility that changes in the oversteer direction such that unstable occurs, sets the upper limit value of the first target yaw rate correction factor K [alpha in order to avoid such a problem to a predetermined value K [alpha _1.

By setting as described above, the throttle opening detection value Acc is changed from the first predetermined value Acc ₁ to a certain value Ac.
between c _2, the more the lateral acceleration detected value Yg is larger, i.e. the maximum value near the cornering force C _F, with respect to the throttle opening detection value Acc appearing as the same accelerator operation, the appear as correction ratio K of the target yaw rate The one target yaw rate correction coefficient Kα is set to be relatively large, and priority is given to the driver's acceleration operation intention in the region where the cornering power itself decreases from the region where the cornering power decreases. Of course, in such a region, since the driver should not greatly perform the steering angle operation by the steering wheel, the operation control target of the driver is almost limited to the accelerator operation, and there is a possibility that the two-sided operation occurs. Absent.

On the other hand, in the four-wheel drive vehicle in which the rear wheel is the main drive wheel, the longitudinal acceleration detection value Xg of the vehicle becomes negative as a result of depression of the brake pedal or shift-down operation which appears as a deceleration operation. The increase in the direction means that, as described above, the load is actively generated on the front wheels, which are the steered wheels, due to the inertia of the vehicle, thereby increasing the load on the front wheels and reducing the cornering force compared to that of the rear wheels. It is understood that the vehicle is intentionally increased to increase the lateral force of the vehicle so as to make a cut inside the turn.
Also in this case, as described above, a region where the cornering force C _F has a margin, that is, a region where the cornering force C _F can be increased almost linearly with an increase in the side slip angle SA, that is, if the steering angle is increased, the vehicle is affected. In a region where the lateral force can be increased linearly, if the negative acceleration, that is, the deceleration operation amount of the driver has a great influence on the correction of the target yaw momentum, the driver's feeling is the steering angle. Control must also be performed, and at the same time, the amount of depression of the brake pedal and the timing of the downshift operation must be controlled, which is not preferable. Therefore, the influence of the correction of the target yawing momentum according to the deceleration operation or the negative acceleration (deceleration) resulting from the deceleration operation is increased only in the region where the cornering power itself decreases from the region where the cornering power decreases. Want to.

Here, as in the case of FIG. 10, a longitudinal acceleration correction coefficient Kb which increases as the lateral acceleration detection value Yg increases is set, and the longitudinal acceleration correction coefficient Kb is multiplied by the longitudinal acceleration detection value Xg. Thus, a target yaw rate correction coefficient during deceleration, in this case, a second target yaw rate correction coefficient Kβ may be set. FIG. 12 is a control map of the correlation between the lateral acceleration detection value Yg and the longitudinal acceleration correction coefficient Kb. Here, the cornering force C _F
Are substantially linearly increased with an increase in the side slip angle SA.
And holding the "0" to the acceleration correction coefficient Kb before and after the region of a predetermined value Yg _21, wherein as the correction of the target yaw rate by the deceleration operation is not performed, the cornering power decreases gradually, eventually cornering force is reduced As a region, the lateral acceleration detection value Yg is the first predetermined value Yg
In ₂₁ to the region of the second predetermined value Yg _22, to increase the longitudinal acceleration correction coefficient Kb, gradually negative direction in inclination of the second lateral acceleration correction coefficient Kb 'with increasing lateral acceleration detected value Yg, lateral acceleration detection value Yg is the second predetermined value Yg ₁₂ more regions to hold the acceleration correction coefficient Kb back and forth in a predetermined value Kb _1. Vehicle the lateral acceleration detected value Yg is the second predetermined value Yg ₂₂ or more areas, and reduced wheel loads of the rear wheels increases load transfer to the front wheel side, the cornering force of the rear wheels as a result of reduced It is assumed that the steering characteristics have greatly changed in the oversteer direction. In such a situation where a large oversteer change occurs, the detected lateral acceleration value Yg also becomes a large value. However, in accordance with the negative acceleration (deceleration) Xg which increases in this situation, the second acceleration detection value Yg is increased.
If the target yaw rate correction coefficient Kβ is set to an excessively large value, the yaw moment acting on the vehicle is further increased, and the oversteer change is promoted, and the vehicle behavior becomes unstable. Therefore, in order for this second target yaw rate correction coefficient Kβ is not excessively set, the lateral acceleration detection value Yg predetermined value is a negative lower limit value of the acceleration correction coefficient Kb before and after the second predetermined value Yg ₂₂ more regions held in Kb _1. Note that the second lateral acceleration correction coefficient Kb 'is calculated backward from each of the predetermined values. The inclination and the second lateral acceleration correction coefficient Kb need not always be constant values.

Negative longitudinal acceleration correction set in this way
Using the coefficient Kb, the second target yaw rate correction coefficient Kβ
Is the longitudinal acceleration detection value according to the control map shown in FIG.
It is set according to Xg. Here, the subtle vehicle speed adjustment range
Is a dead zone, the longitudinal acceleration detection value Xg is 0 to a certain negative
A first predetermined value Xg which is a value₁In the area of
The rate correction coefficient Kβ is held at “1” and
The target yaw rate is not corrected
The acceleration detection value Xg is equal to the first predetermined value Xg.₁~ Some negative
Value Xg_TwoIn the region of, the inclination is calculated by the control map of FIG.
The set longitudinal acceleration correction coefficient Kb and longitudinal acceleration detection
As the output value Xg increases in the negative direction, the second target yaw
Is calculated to a predetermined value Kβ.₁Gradually in the positive direction until
The second target yaw rate correction coefficient Kβ increases by a predetermined value.
Kβ₁A certain value Xg of the longitudinal acceleration detection value Xg_Twothat's all
, The second target yaw rate correction coefficient Kβ is set to a predetermined value.
Kβ ₁To hold. Note that this predetermined value Kβ₁Is the second goal
A positive upper limit value of the yaw rate correction coefficient Kβ, for example,
This second target yaw rate correction coefficient Kβ is set as a correction ratio K.
And the reference yaw rate ψ^'* ₀Multiplied by the target yaw rate
ψ^'*Is calculated, the second target which is the correction ratio K
If the yaw rate correction coefficient Kβ is too large, the actual yaw rate
Target yaw rate for ψ '^'*Is set too large
The result is a large yaw moment in the vehicle.
In an oversteer direction that makes vehicle behavior unstable.
Since such changes may occur, such defects are
To avoid the second target yaw rate correction coefficient Kβ
Limit value to a predetermined value Kβ₁Set to.

With the above setting, when the longitudinal acceleration detection value Xg is between the first predetermined value Xg ₁ and a certain value xg ₂ , the larger the lateral acceleration detection value Yg is, that is, the smaller the cornering force C _F In the vicinity of the maximum value, the second target yaw rate correction coefficient Kβ that appears as the correction rate K of the target yaw rate is set to be relatively large with respect to the negative longitudinal acceleration detection value Xg that appears as a result of the same deceleration operation, and the cornering power decreases. The driver's intention to decelerate in a region where the cornering force itself decreases from the region is given priority and given priority. Of course, in such a region, the driver should not largely perform the steering angle operation using the steering wheel, and therefore, the operation control target of the driver is substantially limited to the deceleration operation, and the two-sided operation occurs. Absent.

The first target yaw rate set as described above
Of the second target yaw rate correction coefficient Kβ
When the longitudinal acceleration detection value Xg is positive, the vehicle
Assuming that both are accelerating, the first target yaw rate correction coefficient K
α is set to the correction ratio K, and the longitudinal acceleration detection value Xg is positive.
If not, the vehicle is deemed to be at constant speed or deceleration.
(2) Set the target yaw rate correction coefficient Kβ to the correction ratio K,
Each set correction ratio K is calculated based on the reference yaw rate ψ^'*
₀And the target yaw rate に よ り ^'*Calculate
Set.

[0049] ^{ψ '* = K · ψ'} * 0 ......... (7) Next, target yaw angular acceleration [psi ^"* is obtained by time differential value of the target yaw angle acceleration [psi ^'* obtained by the Equation 7 From 8 below
Given by the formula. ψ ^“* = V ′ / R V ′ = dV / dt (8) On the other hand, the actual yaw rate ψ ′ of the actual yaw momentum of the vehicle that is actually generated in the vehicle is directly detected by the yaw rate sensor. The actual yaw angular acceleration ψ ″ can be calculated from the time differential value. Instead of the differential operation, it is also possible to adopt a high-pass filter process having an appropriate cutoff frequency.

Next, in order to perform feedback control so that the deviation between the actual yawing momentum and the target yawing momentum becomes zero, each deviation is calculated by the following equation (9) and (10).
The yaw rate difference Δψ 'and the yaw angular acceleration difference Δψ
Deviation between ^{"calculated as. Δψ '= ψ' -ψ '} * ......... (9) Δψ" = ψ "-ψ" * ......... (10) Next, these target yawing momentum and the actual yawing momentum In order to control the actual control system, that is, the clutch mechanism, so that the yaw rate difference Δψ ′
A, by adding the yaw angular acceleration difference [Delta] [phi] ^"obtained by multiplying the control gain K ₃ of a predetermined third, further to its value, by multiplying the control gain K ₂ second predetermined set in advance of, the yaw rate corresponding clutch torque Tψ ′ is calculated according to the following equation (11).

Tψ '= K ₂ · (Δψ' + K ₃ · Δψ ^" ) (11) Here, each control gain will be described. The yaw angular acceleration obtained by differentiating the yaw rate as known is , The phase is advanced by about 90 ° in the complex plane.
The movement of the yaw rate is delayed by about 90 ° with respect to the yaw angular acceleration. Therefore, the yaw angular acceleration difference Δψ "
Is high in response of the control, and the yaw rate difference 制 御 ′ is low in the response of control. Therefore, the second control gain K which is applied to the yaw rate difference ψ ′, for example, according to the response of the control desired for the vehicle. ₂ is set appropriately, and the yaw angular acceleration difference Δ
a third control gain K ₃ that are synergistic with respect to [psi "the control gain K ₂ of the second may be set in advance.

Next, the microcomputer 70 of the controller 58 calculates and outputs the engagement force of the clutch mechanism 37 for controlling the yawing momentum of the vehicle and the control signal based on the principle of the invention. The processing will be described with reference to the flowchart of FIG. This arithmetic processing is performed for a predetermined period ΔT (for example, 20 mse
c) This is executed as a timer interrupt process for each. First, in step S1, a front wheel rotation detection value nF from the front wheel rotation sensor 54 and a rear wheel rotation detection value n from the rear wheel rotation sensor 56
Read R.

Next, the process proceeds to step S2, where the detected steering angle θ from the steering angle sensor 53 and the detected vehicle speed V from the vehicle speed sensor 52 are read. Next, the process proceeds to step S3.
The lateral acceleration detection value Yg from the lateral acceleration sensor 51 is read. Next, the process proceeds to step S4, where the throttle opening detection value Acc from the throttle opening sensor 48 and the longitudinal acceleration detection value Xg from the longitudinal acceleration sensor 49 are read.

Next, the process proceeds to step S5, where the actual yaw rate detection value ψ ′ from the yaw rate sensor 55 is read. Next, the process proceeds to step S6, and the front and rear wheel rotation difference ΔN is calculated according to the above two equations. Next, the routine proceeds to step S7, the first control gain K ₁ is calculated and set according to a pre-stored control maps and the like in the three equations, or the storage device 70c.

[0055] and then proceeds to step S8, back and forth in the wheel rotational difference ΔN calculated in the step S6, to calculate the clutch torque TN by multiplying the first control gain K ₁ calculated set in step S7 . Next, the process proceeds to step S9, and the actual yaw rate detection value ψ ′ read in step S1 is differentiated with respect to time to calculate the yaw angular acceleration ψ ″.

Next, the routine proceeds to step S10, where the reference yaw rate ψ ^{′ *} _{0 is obtained} from the control map shown in FIG. Is calculated and set. Next, proceeding to step S11, it is determined whether the vehicle is accelerating based on whether the longitudinal acceleration detection value Xg read in step S4 is positive, and the longitudinal acceleration detection value Xg is determined.
Is positive, the process proceeds to step S12; otherwise, the process proceeds to step S13.

In the step S12, the step S
The throttle opening correction coefficient Kb corresponding to the lateral acceleration detection value Yg read in 3 is calculated and set from the control map of FIG. Step S1
In step S4, the first target yaw rate correction coefficient Kα corresponding to the throttle opening detection value Acc read in step S4 is calculated using the throttle opening correction coefficient Kb calculated and set in step S12. The calculation is set from the map, and the process proceeds to step S15.

At the step S15, at the step S15
The first target yaw rate correction coefficient Kα calculated and set in step 14
Is set to the correction ratio K, and the routine goes to Step S18. On the other hand, in the step S13, the longitudinal acceleration correction coefficient Ka corresponding to the lateral acceleration detection value Yg read in the step S3 is calculated and set from the control map of FIG. 12, and the process proceeds to step S16.

At the step S16, at the step S16
Using the longitudinal acceleration correction coefficient Ka calculated and set in step 13,
Further, a second target yaw rate correction coefficient Kβ corresponding to the longitudinal acceleration detection value Xg read in step S4 is calculated as shown in FIG.
The calculation is set from the control map described above, and the routine goes to Step S16. In the step S17, the second target yaw rate correction coefficient Kβ calculated and set in the step S16 is set to the correction ratio K, and the routine goes to the step S18.

At the step S18, at the step S18
Using the correction ratio K set in step 15 or step S17 and the reference yaw rate ψ ^{′ *} ₀ set in step S10, the target yaw rate ψ ^{′ *} is calculated according to the above equation (7).
Next, the process proceeds to step S19, where the target yaw angular acceleration ψ ^{″ *} is calculated according to the above-described equation (8 ⁾ that temporally differentiates the target yaw rate ψ ^{′ *} calculated in step S18.

Next, the process proceeds to step S20, in which the target yaw rate ψ ^{′ *} calculated in step S18 is subtracted from the actual yaw rate detection value ψ ′ read in step S5, and the yaw rate difference Δψ ′ is calculated according to the equation (9). calculate. Next, the process proceeds to step S21, where the target yaw angular acceleration ψ ^“*” calculated in step S19 is subtracted from the yaw angular acceleration ψ ”calculated in step S9, and the yaw angular acceleration difference Δψ” is calculated according to the above equation (10). calculate.

Next, the process proceeds to step S22, and using the yaw rate difference Δψ ′ calculated in step S20 and the yaw angular acceleration difference Δψ ″ calculated in step S21, the clutch torque Tψ ′ corresponding to the yaw rate according to the equation (11).
Is calculated. Next, the process proceeds to step S23, in which the clutch torque TN calculated in step S8 and the yaw rate corresponding clutch torque T ク ラ ッ チ ′ calculated in step S22 are calculated.
To calculate the clutch engagement force T.

[0063] and then proceeds to step S24, to form a control signal S _T to achieve clutch engagement force T calculated in step S12, the process returns to the main program and output to the drive circuit 59 . Next, the operation of the vehicle yawing momentum control device of the present embodiment will be described based on the behavior of the vehicle.

Now, it is assumed that the vehicle travels straight at a constant speed on a high-μ good road which is flat without any unevenness on the road surface and has a sufficient friction coefficient. When the vehicle travels straight on a high-μ good road at a constant speed, the ratio of the front and rear distribution of the driving force by the clutch mechanism 37 is set to about 25:75. When the vehicle is traveling straight at a constant speed on such a high μ good road, the front wheel rotation detection value nF calculated in step S6 at each sampling time when the calculation processing in FIG.
And the rear wheel rotation detection value nR, that is, the front-rear rotation difference ΔN is substantially zero. Accordingly, the first control gain K ₁ is step be calculated and set to a certain value S in step S7 in FIG. 7
The clutch torque TN calculated at 8 is substantially zero. On the other hand, since the vehicle is traveling straight, the actual yaw rate detection value ψ ′ detected by the yaw rate sensor 55 is substantially zero, and the differential value of the yaw angular acceleration ψ ″ is also substantially zero. Although the detected vehicle speed value V becomes a certain value, the steering angle detection value θ detected by the steering angle sensor 53 is substantially zero, so the reference value calculated and set in step S10 of the calculation processing in FIG. The yaw rate ψ ^'* also becomes substantially zero, and since the vehicle is traveling at a constant speed, the step S of the arithmetic processing in FIG.
In step S11, it is determined that acceleration is not being performed, and the process proceeds to step S13. However, since the vehicle is traveling straight, the lateral acceleration detection value Yg read in step S3 is also substantially zero, and in step S13, the longitudinal acceleration correction coefficient Kb is set to zero according to the control map of FIG. In step S16, the second target yaw rate correction coefficient Kβ is set to “1” in accordance with the longitudinal acceleration detection value Xg that is substantially zero in accordance with the control map of FIG. Is set to the correction ratio K in step S17.

The second target yaw rate correction of "1"
7 using the correction ratio K set for the coefficient Kβ.
In step S18, the target yaw rate is calculated according to equation (7).
To ^'*Is calculated and set, but the correction ratio K is “1”.
Target yaw rate ψ ^'*Is the criterion that is almost zero
Yaw rateψ^'* ₀And step S1
Target yaw angular acceleration calculated by equation (9) ９^"*Is also almost zero
You. From the above, according to the nine equations in step S20 of the arithmetic processing in FIG.
The calculated yaw rate difference Δψ ′ is also equal to 10 in step S21.
The yaw angular acceleration difference Δψ ”calculated by the equation also becomes substantially zero.
Thus, the yaw calculated in step S22 of the arithmetic processing in FIG.
The rate-corresponding clutch torque T '' becomes substantially zero. Follow
Thus, the class calculated in step S23 of the calculation processing of FIG.
The switch fastening force T becomes substantially zero, and the drive
Control signal S output toward path 59_TIs also substantially zero.

[0066] In the driving circuit 59 receives the control signal S _T of approximately zero in this way, but to convert it driving signal by a floating type constant-voltage circuit and the like, i.e., the command current I _SOL, the command current I _SOL is the Since the neutral command current _IN is obtained, the excitation state of the proportional solenoid 50a of the pressure control valve 50 does not change, and the spool is not moved, so that the secondary side of the pressure control valve 50, that is, the input port of the clutch mechanism 37 The supplied working oil pressure P does not change. Therefore,
The drive distribution ratio to the front and rear wheels is maintained in the medium state of the above-mentioned about 25:75, so that stable constant-speed straight running can be continuously performed.

On the other hand, the rear wheel 2 is placed in a low μ area such as a puddle.
As a result of the entry of RL and 2RR, the rear wheels 2RL and 2RR
, A front-rear rotation difference ΔN between the front wheel rotation detection value nF and the rear wheel rotation detection value nR calculated in step S6 of the calculation processing in FIG. 7 becomes a certain positive value. on the other hand,
Since the first control gain K ₁ of a certain positive value with respect to the lateral acceleration detected value Yg is substantially zero at step S7 is calculated and set, clutch torque TN of one step S8 positive value
Is calculated. On the other hand, the actual yaw rate detection value ψ ′ generated in the vehicle is still substantially zero, and the steering angle detection value θ is still substantially zero.
Yaw rate corresponding clutch torque Tψ ′ calculated at 22
Becomes substantially zero. At this time, even if a negative acceleration (−) Xg acts on the vehicle due to the rear wheels 2RL and 2RR entering a low μ area such as a puddle, the value is also determined in step S1.
The second target yaw rate correction coefficient Kβ, which is smaller than the first predetermined value Xg ₁ as the dead zone in the control map of FIG. 13 and is set to the correction ratio K, is set to “1”. Therefore, the target yaw rate ψ ^{′ *} calculated in step S18 is still substantially zero, and the steps S19 to S19 are not performed.
After that, the clutch torque T ヨ ー ′ corresponding to the yaw rate calculated in step S22 becomes substantially zero. Therefore, the clutch engagement force T calculated in step S23 of the calculation processing in FIG.
Becomes certain positive value, the control signal S _T is also some positive value that is output at the step S24 in order to achieve it.

As described above, the control signal S _T having a certain positive value
In the driving circuit 59 to enter, for converting the high command current I _SOL than the neutral command current I _N and thereby the floating-type constant-voltage circuit and the like, the neutral command current I
Excited state is increased proportional solenoid 50a of the pressure control valve 50 having a large command current I _{SO L} than _N is input, whereby spool secondary side of the pressure control valve 50 moves, i.e., the clutch mechanism 37 The operating oil pressure P supplied to the input port increases. Accordingly, the fastening force of the clutch mechanism 37 increases, and the transmission torque to the front wheels 2FL, 2FR increases. As a result, the drive distribution to the rear wheels 2RL, 2RR becomes smaller than in the above-mentioned medium state, and the front wheels 2RL, 2R become smaller.
R slippage is eliminated and stable constant-speed straight running can be continuously performed.

By the way, from this straight traveling state at a constant speed, the brake pedal is depressed or the downshift operation is performed without steering the steering wheel by the driver's intention. As a result, there is no slip between the front and rear wheels. That is, when a negative acceleration of the vehicle occurs without generating the front-rear wheel rotation difference ΔN, steps S6 to S8 of the calculation processing in FIG.
At the same time, the clutch torque TN is set to substantially zero as in the case of the constant speed straight traveling state. Further, the yaw angular acceleration 算出 ″ calculated in step S9 becomes substantially zero because the detected actual yaw rate detected value ψ ′ is substantially zero, and since the detected steering angle θ is substantially zero, The reference yaw rate ψ ^{′ *} ₀ calculated in S10 also becomes substantially zero.On the other hand, in step S11, since the longitudinal acceleration detection value Xg is negative during deceleration, the process proceeds to step S13. Since the value Yg is substantially zero, the longitudinal acceleration correction coefficient Kb is set to substantially zero according to the control map of Fig. 10. On the other hand, in step S16, the longitudinal acceleration correction coefficient set to substantially zero in step S13 is set. The second target yaw rate correction coefficient Kβ according to the longitudinal acceleration detection value Xg is calculated and set using the coefficient Kb, but regardless of the detected negative longitudinal acceleration detection value (−) Xg, the inclination is calculated. Longitudinal acceleration correction because coefficient Kb is set to substantially zero, the In any second target yaw rate correction factor K becomes
β, that is, the correction ratio K in step S17 is set to substantially “1”. Further, since the reference yaw rate ψ ^{′ *} ₀ calculated in step S10 is substantially zero, step S18
In target yaw rate ψ is calculated also substantially becomes zero ^'* also substantially zero, and the following yaw corresponding clutch torque Tipusai ₁ calculated in step S22 through step S19 to S21',
Therefore, the control signal S _T is also approximately becomes zero, is the same as clutch engagement force control and constant-speed straight running condition following lines output at step S24 in order to achieve a clutch engagement force T which is set to substantially zero at step S23 Thus, the vehicle can be decelerated while keeping the vehicle behavior stable.

In addition, the driver's intention is changed from the constant speed straight traveling state.
Without steering the steering wheel
Step on the dull, as a result there is no slip between the front and rear wheels.
In other words, the front and rear wheel rotation difference ΔN
When an acceleration of the order shown in FIG.
In steps S6 to S8, the vehicle is closed in the same
Latch torque TN is set to substantially zero. Also step
The yaw angular acceleration ψ ″ calculated in S9 is the detected actual yaw
-Since the rate detection value ψ 'is almost zero, it becomes almost zero,
Further, since the detected steering angle θ is substantially zero, step S
Reference yaw rate calculated in 10ψ^'* ₀Is also substantially zero.
On the other hand, in step S11, the longitudinal acceleration detection value during acceleration
Since Xg is positive, the process proceeds to step S12.
Since the detected lateral acceleration detection value Yg is substantially zero,
According to the control map shown in FIG.
a is set to substantially zero. In contrast, step S14
Now, the throttle set to substantially zero in step S12
Throttle opening detection value Acc using opening correction coefficient Ka
The first target yaw rate correction coefficient Kα corresponding to the
However, the detected throttle opening detection value Acc
Regardless, the throttle opening correction coefficient Ka having the above slope is obtained.
Is set to substantially zero, so that the first
Target yaw rate correction coefficient Kα, that is, correction in step S15
The ratio K is set to approximately “1”. Further, the step S
Reference yaw rate calculated in 10ψ^'* ₀Is approximately zero
From the above, the target yaw rate calculated in step S18Ｓ
^'*Is also substantially zero, and the process proceeds through steps S19 to S21.
The clutch torque corresponding to the yaw rate calculated in step S22
Ku Tψ₁Is also substantially zero, and thus becomes substantially zero in step S23.
Steps to achieve the set clutch engagement force T
Control signal S output in S24_TIs also almost zero, and
Clutch engagement force control is performed as in the case of straight running
The vehicle can be accelerated while keeping the vehicle behavior stable.
Wear.

In addition to the above, the same feedback control is performed even when the rear wheels 2RL, 2RR slip due to an excessively large driving force applied to the rear wheels 2RL, 2RR when starting on a low μ road surface, for example. The slip of the rear wheels is eliminated, and the behavior of the vehicle is stabilized. Even if the front wheels 2FL and 2FR slip on the low μ road surface and the front-rear wheel rotation difference ΔN becomes a certain negative value, the rear wheels are controlled according to the principle of the above-described embodiment and the control map shown in FIG. The drive power distribution to the side is not changed and controlled.

On the other hand, it is assumed that the vehicle has shifted from the straight traveling state on the high μ good road to the constant speed turning state. At this time, it is assumed that the turning radius in the constant speed turning state is relatively large. In the turning state in which the turning radius is relatively large at a constant speed, the front wheel rotation detection value which is the average value of the wheel rotation speeds of the front left and right wheels 2FL and 2FR calculated in step S6 in the calculation processing of FIG. It is considered that the deviation between nF and the rear wheel rotation detection value nR, which is the average value of the wheel rotation speeds of the rear left and right wheels 2RL, 2RR, and the front and rear wheel rotation difference ΔN are substantially zero. In step S7 in processing of FIG. 7, the turning state, i.e., the control gain K ₁ in accordance with the change of the lateral acceleration detected value Yg said first generated in accordance with the depth of the turning are calculated and set. However, since the front-rear wheel rotation difference ΔN is substantially zero, the clutch torque TN calculated in step S8 becomes substantially zero. The clutch torque TN calculated to be approximately zero
Is not uniformly changed from the initial stage of turning to the convergence period irrespective of the turning state.

7, the yaw angular acceleration 演算 ″ is calculated in step S9 by time-differentiating the actual yaw rate detection value ψ ′ read in step S5 in step S9. A certain steering angle detection value θ
The reference yaw rate ψ ^{′ *} ₀ is calculated according to the control map shown in FIG. 8 based on the vehicle speed detection value V that is a constant value. At this time, since the vehicle is in a constant speed turning state, the longitudinal acceleration detection value Xg is basically substantially zero. Therefore, the process shifts from step S11 to step S13 to correct the longitudinal acceleration according to the lateral acceleration detection value Yg generated by the turning. The coefficient Kb is set according to the control map of FIG. Since the turning radius is relatively large in the constant speed turning traveling state, the detected lateral acceleration detection value Yg is also a relatively small value. However, in the following step S16, the longitudinal acceleration detection value X
Since g is substantially zero, the second target yaw rate correction coefficient Kβ
Is set to substantially "1" according to the control map of FIG. 13, and this is set to the correction ratio K which is substantially "1" in step S17. Then, in step S18, the target yaw rate ψ ^{′ *} is calculated by multiplying the correction rate K by the reference yaw rate ψ ^{′ *} ₀ according to the above equation 7, but since the correction rate K is substantially “1”, The target yaw rate ψ ^'* is set substantially equal to the reference yaw rate ψ ^{' *} ₀ . Next, at step S19, the target yaw angular acceleration ψ ^{″ *} is calculated according to the above equation (8). Then, the yaw rate difference Δ で ′ calculated by equation (9) at step S20 and the yaw angular acceleration difference Δψ calculated by equation (10) at step S21. "In step S22.
And the yaw rate corresponding clutch torque T according to the above equation (11).
ψ 'is calculated. Here, since the clutch torque TN is substantially zero as described above, the clutch engagement force T calculated in step S23 is substantially equal to the yaw rate corresponding clutch torque Tψ ′, and this clutch engagement force T, ie, the yaw rate corresponding clutch torque control signal S _T for achieving Tipusai 'is formed outputted at step S24.

[0074] The drive circuit 59 which has received the control signal S _T
In the command current I _SOL in accordance with the control signal S _T to output to the proportional solenoid 50a of the pressure control valve 50, corresponding to the command current I _SOL In the pressure control valve 50 to enter the command current I _SOL The supply operating oil pressure P is supplied to the fluid type multi-plate clutch mechanism 37. At this time, for example, when it is assumed that oversteer occurs in the four-wheel drive vehicle of the present embodiment using FR as a base, in such an oversteer state, the steering angle detection value θ and the vehicle speed detection value V which are the steering inputs are used. With respect to the target yaw rate ψ ^{'* and the} target yaw angular acceleration ψ ^"* substantially equal to the set reference yaw rate ψ ^{' *} ₀ , the actually detected yaw rate detected value ψ 'and the differential yaw angular acceleration ψ" Tends to be large. Accordingly, both the yaw rate difference Δψ ′ and the yaw angular acceleration difference Δψ ″ calculated in steps S20 and S21 have a certain positive value. Therefore, the clutch torque Tψ ′ corresponding to the yaw rate calculated in step S22 is a certain positive value. And the clutch engagement force T calculated and output in steps S23 to S24.
Control signal S _T to achieve even a certain positive value corresponding to the yaw rate corresponding clutch torque Tψ '. Thus, the command current I _SOL output from the drive circuit 59 toward the pressure control valve 50, the neutral command current from a large current value than I _N, hydraulic pressure P also the neutral supplied to the clutch mechanism 37 It becomes larger than the operating oil pressure P _N , and the fastening force of the clutch mechanism 37 increases, and as a result,
The distribution of the driving force to the front wheels 2FL, 2FR is increased, and the driving force of the rear wheels 2RL, 2RR is relatively reduced. The oversteer state is eliminated, the vehicle is improved in the neutral steer direction, and the vehicle behavior is stabilized.

On the other hand, assuming that understeer has occurred from the steering characteristics of the vehicle in recent years, in such an understeer state, the detected steering angle θ, which is the steering input, is used.
And a reference yaw rate set according to the detected vehicle speed V.
^'* ₀ substantially equal the target yaw rate ^{[psi' *} and the target yaw angle acceleration [psi ^"* against actual yaw rate detection value measured [psi '
And the differential value of the yaw angular acceleration ψ ″ tend to be small. Therefore, both the yaw rate difference Δψ ′ and the yaw angular acceleration difference Δψ ″ calculated in steps S20 and S21 have certain negative values. Thus, the yaw rate corresponding clutch torque Tψ calculated 'becomes one negative value at step S22, the control signal S _T Again yaw rate corresponding clutch to achieve clutch engagement force T to be calculated form output in step S23~S24 It takes a certain negative value according to the torque Tψ ′. Therefore, the command current I _SOL output from the drive circuit 59 to the pressure control valve 50 is _equal to the neutral command current I _SOL.
Since the smaller current value than _N, the fastening force of the clutch mechanism 37 is reduced by hydraulic pressure P supplied to the clutch mechanism 37 also becomes smaller ones than the neutral operation pressure P _N, the result, the front wheels 2FL, The distribution of the driving force to the 2FR is reduced, the understeer state is eliminated, the vehicle is improved in the neutral steer direction, and the vehicle behavior is stabilized.

As described above, the turning radius is relatively large. As a result, the cornering force C of the front wheels 2FL and 2FR, which are the steered wheels, may be small.
_F is the action of the yawing momentum control device for the vehicle of the present embodiment in a region that increases almost linearly with the steering input.
Now, let us consider a case where the vehicle has shifted to a constant speed turning state in which the turning radius is smaller than this. Here, in order to facilitate understanding, it is assumed that the rotation difference ΔN between the front and rear wheels is still substantially zero.
It is assumed that the clutch torque TN calculated in steps S6 to S8 in the calculation processing of FIG. 7 is still held at substantially zero.

Even in a region where the cornering force of the front wheels 2FL and 2FR does not decrease or the cornering power does not decrease even if the turning radius of the vehicle on the traveling line is reduced, the driver can operate the vehicle in the same manner as described above. Attempts to control the vehicle with steering input. The driver recognizes that a lateral force is generated in the vehicle by a cornering force that increases almost linearly even when the steering input is increased, that is, when the steering angle is increased and the side slip angle of the front wheels is increased. I also feel the lateral acceleration that increases almost linearly. Then, as described above, the reference yaw rate ψ ^{′ *} ₀ calculated and set in step S10 also increases in accordance with the increase in the steering input, that is, the steering angle detection value θ read in step S3 of the calculation processing in FIG.

In the constant speed turning state where the turning radius is small,
Since the vehicle is not accelerating, the process proceeds from step S11 to step S13 in the arithmetic processing of FIG.
The longitudinal acceleration correction coefficient Kb corresponding to the lateral acceleration detection value Yg that increases in 3 is set according to the control map of FIG.
At this time, since the detected lateral acceleration value Yg should be a large value corresponding to the large lateral force generated by the increasing cornering force, the longitudinal acceleration correction coefficient Kb also becomes a considerably large value.

However, since the detected longitudinal acceleration value Xg is still substantially zero, the second target yaw rate correction coefficient Kβ set according to the control map of FIG. 13 according to the detected longitudinal acceleration value Xg is still approximately “1” in step S16. And the second target yaw rate correction coefficient Kβ is set to the correction ratio K in step S17. Accordingly, the target yaw rate [psi calculated set according Formula 7 in step S18 of the arithmetic processing ^'* is the reference yaw rate [psi calculated in the step ^S10' substantially equal to ^* _0, corresponding to the target yaw rate [psi ^'* Hereinafter, in steps S19 to S22, the clutch torque Tψ ′ corresponding to the yaw rate is calculated in the same manner as in the constant speed turning state in which the turning radius is large, and the clutch torque TN has not yet been calculated.
Is substantially zero, the clutch engagement force T calculated in step S23 becomes substantially equal to the yaw rate corresponding clutch torque Tψ ', and the control signal S output in step S24 for achieving this clutch engagement force T is output. _In accordance with _T , the clutch engagement force is controlled and the front and rear wheel drive distribution is controlled in the same manner as in the constant-speed turning state having the large turning radius, and as a result, feedback control for following the actual yawing momentum to the target yawing momentum is performed. .

In this state, when the turning radius of the traveling line further decreases and the steering input, that is, the steering angle of the steering wheel increases, the front wheels 2FL, 2FR, which are the steered wheels, are particularly increased.
The side slip angle increases, and the cornering force eventually decreases. This is perceived by the driver as the lateral acceleration generated in the vehicle decreases and the running line of the vehicle starts to expand slightly outward.

On the other hand, the driver senses that even if the steering angle, which is the steering input, is further increased, it is not possible to cut the traveling line of the vehicle inward of the turn. As a result, the steering characteristic of the vehicle is changed in the oversteer direction, and the yaw moment is used to turn the vehicle into the inside of the turn.

At this time, it is assumed that the clutch torque TN calculated in steps S6 to S8 of the calculation processing in FIG. 7 is still substantially zero, and the detected steering angle θ and the detected vehicle speed V are determined in step S10. Reference yaw rate ψ ^'* ₀
Is calculated and set. When the accelerator operation is performed by depressing the accelerator pedal as described above, the longitudinal acceleration detection value Xg generated in the vehicle and detected becomes positive, and the process proceeds from step S11 to step S12.

At this time, the detected lateral acceleration value Yg
Is a large value according to the large lateral force generated by the maximum value of the cornering force. Therefore, the throttle opening correction coefficient Kb set according to the lateral acceleration detection value Yg according to the control map shown in FIG. 10 is also large. Value. Using the throttle opening correction coefficient Kb thus set to a large value, the first target yaw rate correction coefficient Kα set according to the throttle opening detection value Acc according to the control map shown in FIG. The first target yaw rate correction coefficient Kα is set to be larger as the operation amount of the accelerator pedal is larger, that is, as the throttle opening detection value Acc is larger.
Is set to

As described above, the larger the throttle opening detection value Acc, the larger the first target yaw rate correction coefficient Kα set to a larger value is set as the correction ratio K, and this is set as step S18.
The target yaw rate ψ ^{′ *} calculated by multiplying the reference yaw rate ψ ^{′ *} ₀ by the above equation 7 is a considerably large positive value with respect to the reference yaw rate ψ ^{′ *} ₀ . In addition, the target yaw angular acceleration ψ ^{″ *} calculated by the above equation (8) as a time differential value is also a large positive value.

Therefore, the steps 9 and 9 in steps S20 and S21 are performed.
The yaw rate difference Δψ ′ and the yaw angular acceleration difference Δψ ″ calculated by the equations (10) and (10) are considerably large negative values, and the yaw rate corresponding clutch torque Tψ ′ calculated according to the equation (11) in step S22 is also a considerably large negative value. since the value, thereby it will become the control signal S _T is also considerably large negative value output in step S24 in order to achieve a clutch engagement force T and the clutch engagement force T is calculated in step S23.

Accordingly, the pressure control valve 50 is
The command current I _SOL that is output to the, from the smaller current value than the neutral command current I _N, the clutch mechanism 3
Also hydraulic pressure P supplied to 7 becomes as small than the neutral operation pressure P _N reduced engaging force of the clutch mechanism 37 is, as a result, the front wheels 2FL, the vehicle driving force distribution is reduced to 2FR The steering characteristic changes in the direction of oversteer, and the yaw moment generated in the vehicle is promoted by this, and the vehicle tries to cut inside the traveling line.

In addition, as described above, especially the front wheels 2FL, 2FR
In the region where the increasing rate of the cornering force is reduced or the cornering force itself is reduced, the driver may decelerate the front wheels 2FL and 2FR for the above-described reason.
It is also conceivable to recover the cornering force of the vehicle and thereby make the vehicle cut into the inside of the turn. Also, the deceleration operation is executed when the approach speed of the vehicle is too large for the predicted size of the corner. This deceleration operation may be performed, for example, by depressing a brake pedal, or may be performed by a downshift operation.

At this time, the clutch torque TN calculated in steps S6 to S8 of the calculation processing of FIG.
Is still substantially zero, and in step S10, the reference yaw rate ψ ^'* according to the detected steering angle θ and the detected vehicle speed V
₀ is calculated and set. In any case as described above, when the deceleration operation is performed, the longitudinal acceleration detection value Xg generated in the vehicle and detected becomes negative, so that the process proceeds from step S11 to step S13.

At this time, the detected lateral acceleration detection value Yg
Is a large value according to the large lateral force generated by the maximum value of the cornering force. Therefore, the longitudinal acceleration correction coefficient Ka set according to the lateral acceleration detection value Yg according to the control map shown in FIG. Value. Using the longitudinal acceleration correction coefficient Ka set to such a large negative value, the second target yaw rate correction coefficient Kβ set according to the longitudinal acceleration detection value Xg in step S16 according to the control map shown in FIG. For example, the larger the depression amount of the brake pedal, that is, the larger the negative longitudinal acceleration detection value (−) Xg generated in the vehicle, the larger the value. You.

As described above, the negative longitudinal acceleration detection value (−) X
The second target yaw rate correction coefficient Kβ, which is set to a larger value as g increases, is set as a correction ratio K,
The target yaw rate ψ ^{′ *} calculated by multiplying the reference yaw rate ψ ^{′ *} ₀ by the above equation at 18 is the reference yaw rate ψ ^{′ *} _0.
Has a considerably large positive value. Further, the target yaw angular acceleration ψ ^“* calculated as the time differential value by the above equation (8 ⁾
Is also a large positive value.

Accordingly, the steps 9 and 9 in steps S20 and S21 are performed.
The yaw rate difference Δψ ′ and the yaw angular acceleration difference Δψ ″ calculated by the equations (10) and (10) are considerably large negative values, and the yaw rate corresponding clutch torque Tψ ′ calculated according to the equation (11) in step S22 is also a considerably large negative value. since the value, thereby it will become the control signal S _T is also considerably large negative value output in step S24 in order to achieve a clutch engagement force T and the clutch engagement force T is calculated in step S23.

Accordingly, the pressure control valve 50 is
The command current I _SOL that is output to the, from the smaller current value than the neutral command current I _N, the clutch mechanism 3
Also hydraulic pressure P supplied to 7 becomes as small than the neutral operation pressure P _N reduced engaging force of the clutch mechanism 37 is, as a result, the front wheels 2FL, the vehicle driving force distribution is reduced to 2FR The steering characteristic changes in the direction of oversteer, and the yaw moment generated in the vehicle is promoted by this, and the vehicle tries to cut inside the traveling line.

Here, in order to verify the accuracy of the control,
For example, it is assumed that a vehicle longitudinal acceleration unintended by the driver occurs when traveling on a slope such as a slope.
For example, it is assumed that a negative longitudinal acceleration is generated by a gravitational acceleration in a vehicle turning on an uphill slope. In this case, if the actual vehicle speed is too high with respect to the size of the corner that can be recognized by the driver according to the cornering characteristics of the vehicle, a further deceleration operation will be performed. On the other hand, if the negative longitudinal acceleration due to the gravitational acceleration matches the size of the corner, no further deceleration operation is performed,
It is recognized that the negative longitudinal acceleration due to the gravitational acceleration can maintain the traveling line at the corner. Accordingly, the vehicle holds the traveling line without expanding outside the traveling line by the control based on the deceleration acting on the vehicle, that is, the longitudinal acceleration detection value Xg when the vehicle is not accelerating in the arithmetic processing of FIG. be able to.

On the other hand, it is assumed that a positive longitudinal acceleration is generated by a gravitational acceleration in a vehicle turning on a downhill slope. Even during acceleration on such a downhill, if the driver intends to reduce the vehicle speed, at least the acceleration operation, that is, the accelerator pedal is not depressed. Here, when it is determined that the vehicle speed and the positive longitudinal acceleration that are balanced with the back torque of the engine brake or the like match the size of the corner, the driver inputs the steering input, that is, the steering angle. A driver who is familiar with the cornering characteristics of a vehicle,
It will be considered that the traveling line can be held only at the reference yaw rate (reference yawing momentum) given by the vehicle speed and the steering angle in the calculation processing of FIG. At this time,
In the calculation processing of FIG. 7, since the acceleration operation, that is, the throttle opening detection value Acc is zero, the target yaw rate becomes equal to the reference yaw rate. Therefore, the actual yaw momentum follows the reference yaw momentum as intended by the driver. The running line can be maintained.

By the way, if the control during acceleration due to the gravitational acceleration on the downhill or the like is substituted by only the positive vehicle longitudinal acceleration, the target yaw momentum increases during the downhill / acceleration. In other words, the driver tries to go deeper into the traveling line at the corner where the driver has determined that the vehicle should turn at the vehicle speed and the steering angle under the circumstances. , Or a downshift operation, and an operation to reduce the steering angle must be performed.

As described above, the vehicle yawing momentum control apparatus of this embodiment can achieve a vehicle behavior that accurately grasps the driver's intention under any circumstances. In controlling the yawing momentum during the deceleration, the deceleration operation amount may be directly detected by using the brake pedal depression amount or the brake fluid pressure instead of the negative longitudinal acceleration. In other words, by setting at least one of the acceleration / deceleration state physical means that the acceleration / deceleration state physical quantity capable of judging the intention from the handling of the driver, the acceleration / deceleration generated in the vehicle regardless of the driver's intention is controlled. Inconsistencies can be avoided.

Of course, even when a rotational speed difference occurs between the front and rear wheels during turning and turning, the clutch engagement force T calculated in step S12 in the calculation processing of FIG. Is the sum of the clutch torque TN based on
While appropriately controlling the yawing momentum, it is also possible to appropriately correct the difference between the rotational speeds.

In the above-described embodiment, the yawing momentum control device for simultaneously correcting the front and rear wheel rotation difference has been described.
This need not always be performed at the same time, and when this correction control function is to be deleted, steps S6 to S8 in the arithmetic processing of FIG. 7 may be deleted. Therefore, step S2 in the arithmetic processing of FIG. 7 corresponds to the steering angle detecting means and the vehicle speed detecting means of the vehicle yawing momentum control device of the present invention, and similarly, step S10 corresponds to the reference yawing momentum calculating means. Step S4 corresponds to the longitudinal acceleration / deceleration state detecting means, step S3 corresponds to the lateral acceleration detecting means, steps S11 to S17 correspond to the correction amount calculating means, steps S5 and S9 correspond to the yawing momentum detecting means, Steps S18 and S19 correspond to the target yawing momentum calculating means, and steps S20 to S2
4 corresponds to feedback control means.

In the above embodiment, a four-wheel drive vehicle based on a rear-wheel drive vehicle has been described in detail. It may control a clutch mechanism of a transfer mounted on a wheel drive vehicle. In this case, the calculation may be performed assuming that the above-described front and rear wheel rotation difference ΔN = nF−nR.

In the above-described embodiment, the case where a hydraulic friction clutch driven by hydraulic pressure is used as the clutch mechanism has been described. Can be adopted. In the above-described embodiment, a case has been described in which a microcomputer is applied as the controller 58. Alternatively, an electronic circuit such as a counter and a comparator may be combined.

Further, in the above-described embodiment, the case where the hydraulic oil is applied as the working fluid for biasing the variable torque clutch has been described. No. Further, the pressure control valve is not limited to the pressure reducing valve, and a pressure control valve capable of controlling the pressure on the secondary side in response to another command value may be applied.

[0102] The rotary drive source of the oil pump is not limited to the electric motor, and the rotational output of the engine can be used. Further, in the above-described embodiment, only the case where the yaw momentum control device of the vehicle is applied to the driving force distribution device between the front and rear wheels has been described in detail. Apparatus that performs feedback control for following the actual yawing momentum that is generated is applicable to any control apparatus. , An active suspension and stabilizer control device that enables variable roll stiffness control described in Japanese Patent Laid-Open No. 5-193332 previously proposed by the present applicant, or Braking force control for individually controlling the braking force of each wheel of a vehicle described in Japanese Patent Application Laid-Open No. Hei 5-24528 Location, or by the applicant is widely deployed in the differential limiting control apparatus that distributes transmitting the driving force to left and right wheels as described in JP-A-2-290722 previously proposed.

[0103]

As described above, according to the apparatus for controlling the yawing momentum of the vehicle of the present invention, the operation performed in addition to the steering angle operation is performed from the region where the increasing rate of the cornering force decreases to the region where the cornering force itself decreases. The target yawing momentum is corrected in accordance with the driver's acceleration / deceleration operation, and the effect of this correction is increased in accordance with the increase in the lateral acceleration that occurs with the increase in the side slip angle, thereby realizing the dual operation of the driver. While avoiding the above problem, the vehicle is cut into the inside of the turning of the vehicle with respect to the traveling line, so that the traveling line can be prevented from expanding outward as in the related art.

[Brief description of the drawings]

FIG. 1 is a basic configuration diagram of a vehicle yawing momentum control device of the present invention.

FIG. 2 is a schematic configuration diagram showing an example in which the yawing momentum control device for a vehicle of the present invention is applied to a driving force distribution control device between front and rear wheels.

FIG. 3 is a schematic configuration diagram illustrating an example of a driving force distribution control device between front and rear wheels in FIG. 2;

4 is a diagram showing a correlation between a supply working oil pressure and a transmission torque to a front wheel side performed by a driving force distribution control device between front and rear wheels in FIG. 3;

5 is a diagram showing a correlation between a command current and a supply hydraulic pressure performed by a driving force distribution control device between front and rear wheels in FIG. 3;

6 is a diagram showing a correlation between front and rear wheel rotation differences and transmission torque to a front wheel performed by a driving force distribution control device between front and rear wheels in FIG. 3;

FIG. 7 is a flowchart showing a calculation process of the first embodiment of the yawing momentum control device for a vehicle according to the present invention.

8 is a control map for calculating and setting a reference yaw rate using a vehicle speed detection value as a parameter with respect to a steering angle detection value in the calculation processing of FIG. 7;

FIG. 9 is a correlation diagram of a tire characteristic appearing in a side slip angle and a cornering force.

10 is a control map for calculating and setting a throttle opening correction coefficient with respect to a lateral acceleration detection value in the calculation processing of FIG. 7;

11 is a control map for calculating and setting a first target yaw rate correction coefficient with respect to a throttle opening detection value using the throttle opening correction coefficient set in FIG. 10 in the calculation processing of FIG. 7;

12 is a control map for calculating and setting a longitudinal acceleration correction coefficient with respect to a lateral acceleration detection value in the calculation processing of FIG. 7;

FIG. 13 is a diagram illustrating an example of calculation of the longitudinal acceleration using the longitudinal acceleration correction coefficient set in FIG.
9 is a control map for calculating and setting a target yaw rate correction coefficient.

[Description of Signs] 1 is an engine 2FL to 2RR is a front left wheel to a rear right wheel 3 is a driving force system 4 is a driving force distribution control device 12 is a transmission 14 is a transfer 16 is a front wheel side output shaft 18 is a front wheel side differential gear 20 Is the front wheel side drive shaft 22 is the propeller shaft 24 is the rear wheel side differential gear 26 is the rear wheel side drive shaft 35 is the fluid pressure source 37 is the clutch mechanism 48 is the throttle opening sensor 49 is the longitudinal acceleration sensor 50 is the pressure control valve 51 is Lateral acceleration sensor 52 is a vehicle speed sensor 53 is a steering angle sensor 54 is a front wheel rotation sensor 56 is a rear wheel rotation sensor 58 is a controller 59 is a drive circuit 70 is a microcomputer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI // B62D 101: 00 103: 00 111: 00 123: 00 (56) References JP-A-3-292221 (JP, A) JP-A-5-58180 (JP, A) JP-A-4-19230 (JP, A) JP-A-4-154430 (JP, A) JP-A-5-124452 (JP, A) JP-A-3-70633 ( JP, A) JP-A-60-161255 (JP, A) JP-A-1-204826 (JP, A) JP-A-2-68225 (JP, A) JP-A-3-31030 (JP, A) JP JP-A-5-24528 (JP, A) JP-A-5-24422 (JP, A) JP-A-5-193332 (JP, A) JP-A-6-72169 (JP, A) (58) Fields investigated (Int) .Cl. ⁷ , DB name) B60K 23/04 B60K 17/348 B60G 17/015 B60T 8/58 B62D 6/00

Claims (2)

(57) [Claims] An input physical quantity detecting means for detecting an input acting on the vehicle or a physical quantity generated in the vehicle, the vehicle comprising at least acceleration / deceleration in the front-rear direction of the vehicle and acceleration / deceleration operation amounts by a driver. A front / rear acceleration / deceleration state detecting means for detecting a front / rear acceleration / deceleration state of the vehicle, a steering angle detecting means for detecting a steering angle given as a steering input, and a vehicle speed detecting means for detecting a front / rear direction vehicle speed of the vehicle. A yawing momentum detecting means for detecting a yawing momentum generated in the vehicle, and a reference based on at least a steering angle detection value detected by the steering angle detecting means and a vehicle speed detection value detected by the vehicle speed detecting means. A reference yawing momentum calculating means for calculating a reference yawing momentum as a yawing momentum; and a longitudinal acceleration / deceleration detected by the longitudinal acceleration / deceleration state detecting means. Correction amount calculating means for calculating a correction amount of the reference yawing momentum which increases with an increase in the front / rear acceleration / deceleration state detection value, based on the state detection value; and reference yawing momentum calculated by the reference yawing momentum calculating means Is corrected by the correction amount calculated by the correction amount calculating means to calculate a target yawing momentum to be achieved by the vehicle, and a target yawing momentum calculated by the target yawing momentum calculating means. A yaw momentum control device for a vehicle, comprising: feedback control means for performing feedback control so that the yaw momentum detected by the yaw momentum detection means coincides. 2. The apparatus according to claim 1, wherein said input physical quantity detection means includes a lateral acceleration detection means for detecting at least a lateral acceleration acting on the vehicle, and said correction amount calculation means calculates a lateral acceleration detection value detected by said lateral acceleration detection means. The yaw momentum control device for a vehicle according to claim 1, wherein the influence of the correction by the correction amount of the reference yaw momentum according to the detected value of the front / rear acceleration / deceleration state is increased in accordance with the increase.