JP2569964B2 - Drive wheel differential limiter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive wheel differential limiting device which can arbitrarily change a differential restraining torque for a pair of left and right drive wheels based on a road surface condition. .

[0002]

2. Description of the Related Art Generally, in a vehicle of a type running on a road via wheels, a differential device is interposed between an engine and a pair of left and right drive wheels to obtain a difference in peripheral speed of the drive wheels when the vehicle turns. Is tolerable.

[0003] For this reason, the road surface condition is greatly different between the left and right, for example, one is a road surface having a low friction coefficient such as a frozen road and the other is a road surface having a high friction coefficient such as dry asphalt. When the vehicle travels on the road surface, the driving force of the engine is transmitted exclusively to the drive wheel side with low road surface resistance by the function of the differential device. As a result, only one of the drive wheels runs idle and the vehicle does not travel. It may be possible.

In order to prevent such a problem, conventionally, a differential restraint device that restrains the function of the differential device to hold the pair of left and right drive wheels in a directly connected state, or a differential restraint torque for the differential device. A differential limiting device or the like in which a peripheral speed difference between a pair of left and right driving wheels is suppressed to be equal to or less than a predetermined value is incorporated in the differential device.

[0005]

SUMMARY OF THE INVENTION In the case of a vehicle incorporating a differential restraint device, the differential restraint device is released so that the function of the differential device can be canceled or the function of the differential device can be activated by the driver's judgment. Must be appropriately operated, the operation is troublesome, and a certain degree of skill is required for the operation of the differential restraint device.

On the other hand, in the case of a vehicle incorporating a differential limiting device, the differential limiting torque of the conventional differential limiting device is constant irrespective of the road surface condition. There are cases. In particular, if the differential limiting device is provided with a large differential restraining torque in consideration of traveling on a road surface having a low friction coefficient, problems such as difficulty in turning the vehicle when turning on a general road surface occur.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to arbitrarily change a differential restraining torque for a pair of left and right driving wheels based on a road surface condition without impairing turning performance of the vehicle. It is an object of the present invention to provide a drive wheel differential limiting device capable of always generating an appropriate differential restraining torque.

[0008]

Differential limiting device for a drive wheel according to the present invention SUMMARY OF THE INVENTION comprises a restraining torque adjusting clutch which can arbitrarily adjust the differential restraint torque to the left and right wheels, of the vehicle traveling shaped
Running state detecting means for detecting a running state;
A differential restraint torque calculating unit that calculates a differential restraint torque of the restraint torque adjusting clutch based on a traveling state detected by a step; a road surface μ estimating unit that estimates a friction coefficient of a road surface; so that the larger based-out road surface friction coefficient is small coefficient of friction is estimated road surface by
The differential restraint torque and the road surface μ-correction unit for correcting the differential restraint torque calculated in the calculating unit, the serial restraining torque adjusting clutch to obtain the differential constraint torque output from the road surface μ-correction unit to And an electronic control unit for controlling the differential restraint torque of the above.

[0009]

The running state of the vehicle is detected by the running state detecting means.
When issued , the differential restraint torque calculating unit calculates the differential restraint torque of the restraint torque adjusting clutch based on the running state . On the other hand, when the road surface μ estimating means estimates the friction coefficient of the road surface, the road surface μ correction calculation unit calculates the differential constraint torque calculated by the differential constraint torque calculation unit based on the friction coefficient of the road surface so that the road surface friction coefficient is small. Modify to be larger . Then, the electronic control unit controls the operation of the clutch for adjusting the restraining torque in accordance with the differential restraining torque corrected by the road surface μ correcting calculation unit, and the differential restraining torque for the drive wheels is appropriately adjusted.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 showing the concept of an embodiment in which a drive wheel differential limiting device according to the present invention is applied to a front wheel drive type vehicle equipped with an engine output control device, and a diagram showing a schematic structure of the vehicle. As shown in FIG. 2, an input shaft 14 of a hydraulic automatic transmission 13 is connected to an output shaft 12 of the engine 11. The hydraulic automatic transmission 13 is configured to operate the engine 1 in accordance with the position of a select lever (not shown) selected by a driver and the driving state of the vehicle.
A predetermined gear position is automatically selected via a hydraulic control device 16 based on a command from an electronic control unit (hereinafter, referred to as an ECU) 15 for controlling the operation state of the vehicle. The specific configuration and operation of the hydraulic automatic transmission 13 are described in, for example, Japanese Patent Application Laid-Open No. 58-5427.
No. 0, Japanese Patent Application Laid-Open No. 61-31749, and the like, as already known. In the hydraulic control device 16, the engagement operation of a plurality of frictional engagement elements constituting a part of the hydraulic automatic transmission 13 is performed. In this embodiment, a pair of shift control solenoid valves (not shown) for performing the opening operation and the opening operation are incorporated. It is intended to achieve a smooth shifting operation to any one of the one gear stages.

Between the output shaft 63 of the hydraulic automatic transmission 13 and the front wheels 64, 65, which are a pair of left and right driving wheels, a clutch 89 for adjusting the restraining torque capable of arbitrarily changing the differential restraining torque is incorporated. However, a differential device 90 is interposed. In the present embodiment, an electromagnetic clutch is employed as the restraint torque adjusting clutch 89, and the clutch coupling force, that is, the differential restraint torque can be arbitrarily changed by changing the amount of current supplied to the electromagnetic clutch. other,
Naturally, it is also possible to employ a clutch or the like capable of arbitrarily changing the coupling force using a fluid pressure or the like.

Therefore, by continuously changing the energizing amount to the restricting torque adjusting clutch 89 according to the road surface condition, as shown in FIG. 3 showing the relationship between the energizing amount and the differential restricting torque at this time, By continuously changing the differential restraining torque of the front wheels 64 and 65, the rotational difference between the front wheels 64 and 65 can be optimally controlled.

In this embodiment, in order to reduce the driver's steering force, a power steering device is incorporated in the steering mechanism. As shown in FIG. 4 showing the concept of the power steering device, the pair of left and right front wheels 64 is used. , 65 is a power steering device 92 composed of a rack and pinion mechanism (not shown) connected to the steering wheel 85 and a power actuator 91 connected to the rack and pinion mechanism.
Are connected to each other via tie rods 93. The hydraulic pump 9 is connected to the power actuator 91 via a steering valve 94 that switches the flow of pressure oil to the power actuator 91 in accordance with the operation of the steering handle 85.
5 is connected. A reservoir tank 96 for storing pressure oil is connected to the hydraulic pump 95 driven by the engine 11 and the power actuator 91.

Therefore, when the steering wheel 85 is turned by the driver, the flow of the pressure oil from the hydraulic pump 95 to the power actuator 91 is switched via the steering valve 94, and the flow corresponds to the steering direction of the steering wheel 85. As a result of the steering force being transmitted to the rack and pinion mechanism via the power actuator 91, the front wheels 64, 6 can be driven with a small steering force.
5 is steered.

In the middle of an intake pipe 18 connected to a combustion chamber 17 of the engine 11, the opening degree of an intake passage 19 formed by the intake pipe 18 is changed, and the amount of intake air supplied into the combustion chamber 17 is changed. A throttle body 21 incorporating a throttle valve 20 for adjusting the pressure is interposed. As shown in FIG. 1 and FIG. 5 showing an enlarged cross-sectional structure of a cylindrical portion of the throttle body 21, both ends of a throttle shaft 22 integrally having a throttle valve 20 fixed to the throttle body 21 are rotatable. Supported. An accelerator lever 23 and a throttle lever 24 are coaxially fitted to one end of the throttle shaft 22 protruding into the intake passage 19.

The throttle shaft 22 and the accelerator lever 2
Bush 26 and spacer 27
The accelerator lever 23 is rotatable with respect to the throttle shaft 22. Further, a washer 28 and a nut 29 attached to one end of the throttle shaft 22 allow the accelerator lever 23
Is prevented from coming off. An accelerator pedal 31 operated by a driver is connected to a cable receiver 30 integral with the accelerator lever 23 via a cable 32. The accelerator lever 23 is connected to the throttle shaft in accordance with the depression amount of the accelerator pedal 31. 22.

On the other hand, the throttle lever 24 is fixed integrally with the throttle shaft 22. Therefore, by operating the throttle lever 24, the throttle valve 2
0 rotates together with the throttle shaft 22. A collar 33 is fitted coaxially and integrally with the cylinder portion 25 of the accelerator lever 23, and is engaged with a claw portion 34 formed on a part of the collar 33 at the tip of the throttle lever 24. A stopper 35 is formed. The pawl portion 34 and the stopper 35 are engaged with each other when the throttle lever 24 is turned in a direction in which the throttle valve 20 opens or the accelerator lever 23 is turned in a direction in which the throttle valve 20 closes. Is set in a proper positional relationship.

Between the throttle body 21 and the throttle lever 24, a stopper 35 of the throttle lever 24 is provided with a claw 3 of a collar 33 integrated with the accelerator lever 23.
4, a torsion coil spring 36 that urges the throttle valve 20 in the opening direction is coaxial with the throttle shaft 22 via a pair of cylindrical spring receivers 37 and 38 fitted to the throttle shaft 22. It has been installed. or,
Also between the stopper pin 39 protruding from the throttle body 21 and the accelerator lever 23, the claw portion 34 of the collar 33 is pressed against the stopper 35 of the throttle lever 24 to urge the throttle valve 20 in the closing direction, and the accelerator pedal 31 A torsion coil spring 40 for giving a sense of detent to the cylinder portion 25 of the accelerator lever 23 via the collar 33 is mounted coaxially with the throttle shaft 22.

At the tip of the throttle lever 24,
The distal end of a control rod 43 whose base end is fixed to the diaphragm 42 of the actuator 41 is connected. A compression coil spring 45 for pressing the stopper 35 of the throttle lever 24 together with the torsion coil spring 36 against the claw portion 34 of the collar 33 to urge the throttle valve 20 in the opening direction is provided in a pressure chamber 44 formed in the actuator 41. Is incorporated. Then, the spring force of the torsion coil spring 40 is set to be larger than the sum of the spring forces of these two springs 36 and 45.
The throttle valve 20 is not opened unless the operator steps on the throttle valve.

A surge tank 46 connected to the downstream side of the throttle body 21 to form a part of the intake passage 19
Is connected to a vacuum tank 48 via a connection pipe 47, and the vacuum tank 48 and the connection pipe 47 are connected to each other.
Between the vacuum tank 48 and the surge tank 4
A check valve 49 that allows only the movement of air to 6 is interposed. Thus, the pressure in the vacuum tank 48 is set to a negative pressure substantially equal to the lowest pressure in the surge tank 46.

The inside of the vacuum tank 48 and the pressure chamber 44 of the actuator 41 are in communication with each other via a pipe 50. An electromagnetic valve 51 is provided. That is, the pipe 50 is connected to the torque control solenoid valve 51.
A spring 54 for urging the plunger 52 against the valve seat 53 so as to close the valve is incorporated.

Further, a pipe 55 communicating with the intake passage 19 upstream of the throttle valve 20 is provided in a pipe 50 between the first torque control solenoid valve 51 and the actuator 41.
Is connected. A non-energized second torque control solenoid valve 56 is provided in the middle of the pipe 55. That is, the spring 5 for urging the plunger 57 to open the pipe 55 is provided to the torque control solenoid valve 56.
8 are incorporated.

The two torque control solenoid valves 51, 56
Are connected to the ECU 15, respectively.
5 on the basis of the command from the torque control solenoid valves 51 and 56.
The on / off of the energization of the power supply is duty-controlled.

For example, when the duty ratio of the torque control solenoid valves 51 and 56 is 0%, the pressure chamber 44 of the actuator 41 is connected to the intake passage 19 upstream of the throttle valve 20.
Atmospheric pressure which is almost equal to the pressure inside the throttle valve 20
Corresponds one-to-one to the depression amount of the accelerator pedal 31. Conversely, when the duty ratios of the torque control solenoid valves 51 and 56 are 100%, the pressure chamber 44 of the actuator 41 has a negative pressure substantially equal to the pressure in the vacuum tank 48, and the control rod 43 is inclined leftward in FIG. As a result, the throttle valve 20 is closed irrespective of the depression amount of the accelerator pedal 31, and the driving torque of the engine 11 is forcibly reduced. In this way,
By adjusting the duty ratio of the torque control solenoid valves 51 and 56, the opening degree of the throttle valve 20 can be changed irrespective of the depression amount of the accelerator pedal 31, and the drive torque of the engine 11 can be adjusted arbitrarily.

In this embodiment, the opening of the throttle valve 20 is controlled simultaneously by the accelerator pedal 31 and the actuator 41. However, two throttle valves are arranged in series in the intake passage 19, and one throttle valve is arranged in the intake passage 19. It is also possible to connect the valve only to the accelerator pedal 31 and to connect the other throttle valve only to the actuator 41, and to control these two throttle valves independently.

On the other hand, a fuel injection nozzle 59 of a fuel injection device for injecting fuel (not shown) into the combustion chamber 17 of the engine 11 is provided at the downstream end of the intake pipe 18 in each cylinder of the engine 11 (four cylinders in this embodiment). The fuel is supplied to the fuel injection nozzle 59 via an electromagnetic valve 60 which is provided correspondingly to the internal combustion engine of the cylinder and is duty-controlled by the ECU 15.
Supplied to That is, by controlling the valve opening time of the solenoid valve 60, the amount of fuel supplied to the combustion chamber 17 is adjusted, and a predetermined air-fuel ratio is reached, so that the ignition plug 6
1 to be ignited.

[0027] wherein the ECU 15, the crank angle sensor 62 for detecting the mounted by the engine speed N _E of the engine 11, the peripheral speed of the pair of left and right front wheels 64 and 65 is a driving wheel (hereinafter, the front wheel this A pair of front wheel rotation sensors 66 and 97 for detecting V _FL and V _FR , respectively, and an opening of the throttle lever 24 attached to the throttle body 21 (hereinafter referred to as a throttle opening).
In addition to the throttle opening sensor 67 for detecting θ _T and the idle switch 68 for detecting the fully closed state of the throttle valve 20, it is assembled in the air cleaner 69 at the tip of the intake pipe 18 to the combustion chamber 17 of the engine 11. An air flow sensor 70 such as a Karman vortex flow meter that detects the amount of air flowing through the water, a water temperature sensor 71 that is mounted on the engine 11 to detect the cooling water temperature of the engine 11, and an exhaust gas that is mounted in the middle of an exhaust pipe 72. An exhaust gas temperature sensor 74 for detecting the temperature of the exhaust gas flowing in the passage 73, an ignition key switch 75, and an operating pressure of a power steering device 92 (hereinafter referred to as an operating pressure) attached to a pair of left and right pressure chambers (not shown) of the power actuator 91. , This is called the power steering pressure) P
A pair of pressure sensors 98 and 99 for detecting _S are connected.

The crank angle sensor 62, the front wheel rotation sensors 66 and 97, and the throttle opening sensor 6
7 and idle switch 68 and air flow sensor 70
Output signals from the water temperature sensor 71, the exhaust temperature sensor 74, the ignition key switch 75, and the pressure sensors 98, 99 are sent to the ECU 15.

A driving force control unit for calculating a target driving torque of the engine 11 (hereinafter referred to as TCL)
An accelerator opening sensor 7 attached to the throttle body 21 together with the throttle opening sensor 67 and the idle switch 68 for detecting the opening θ _A of the accelerator lever 23 (hereinafter referred to as the accelerator opening) 76A.
7, rear wheel rotation sensors 80 and 81 for detecting peripheral speeds V _RL and V _RR of a pair of left and right rear wheels 78 and 79 as driven wheels, respectively, and a vehicle 82. The steering angle sensor 84 for detecting the turning angle δ _H of the steering shaft 83 during turning (hereinafter referred to as the steering shaft turning angle) based on the straight running state of the steering shaft 83, and the steering handle 85 integrated with the steering shaft 83. (almost straight state becomes such a phase is included in this vehicle 82) and the steering shaft reference position sensor 86 for detecting a [delta] _N has successfully connected phase of each time, the sensors 7
Output signals from 7, 80, 81, 84 and 86 are sent to the TCL 76, respectively.

[0030] The ECU 15 and the TCL76 is tied via the communication cable 87, in addition to the information of the operating state of the engine 11 of the detection signals from the engine speed N _E and an idle switch 68 from the ECU 15, the front wheel Information such as the speeds V _FL and V _FR and the coefficient of friction of the road surface (hereinafter referred to as the road surface μ) are sent to the TCL 76. Conversely, the traveling speed of the target driving torque T _O and vehicle 82 is calculated from the TCL76 at the TCL76 (hereinafter, referred to as vehicle speed) in addition and V, the slow steering shaft turning angle [delta] _H and ignition timing Information on the angle ratio and the like are sent to the ECU 15.

In this embodiment, the front wheels 66, 9 serving as drive wheels are provided.
Control for setting the differential constraint torque _TF of the constraint torque adjusting clutch 89 based on the absolute value | V _FL -V _FR | of the peripheral speed difference (front wheel speed difference) of FIG. On the other hand, when the slip amount s in the front-rear direction of the front wheels 64 and 65 is larger than a preset amount, the driving torque of the engine 11 is reduced to ensure maneuverability and reduce energy loss. The target drive torque T _OS of the engine 11 when the control for preventing (hereinafter, referred to as slip control) is performed, and the lateral acceleration generated in the turning vehicle (hereinafter, referred to as lateral acceleration). When _GY becomes equal to or more than a preset value, control is performed to reduce the driving torque of the engine 11 so that the vehicle 82 does not deviate from the turning circuit (hereinafter, this will be referred to as turning control). Institution 11 of the case Respectively calculating a target driving torque T _OC at TCL76, the two target driving torque T _OS,
The optimum final target drive torque T _O is selected from T _OC so that the drive torque of the engine 11 can be reduced as necessary. Also, the throttle valve 2 via the actuator 41
By total closing operation of 0, by considering the case where the output reduction of the engine 11 is not in time to set the target retard amount p _o of the ignition timing, and to quickly reduce the driving torque of the engine 11.

As shown in FIG. 6 showing the general flow of the control according to the present embodiment, in the present embodiment, the target drive torque T _OS of the engine 11 when the slip control is performed and the turning control are performed. The target drive torque T _OC of the engine 11 is always calculated in parallel by the TCL 76, and an optimal final target drive torque T _O is selected from these two target drive torques T _OS and T _OC, and the drive of the engine 11 is performed. While the torque is reduced as required, the differential restraining torque _TF of the restraining torque adjusting clutch 89 is changed according to the running state of the vehicle 82 and the road surface μ.

More specifically, when the ignition key switch 75 is turned on, the control program of this embodiment is started. At M1, first, the steering axis turning position initial value δm ₍₀₎ is read, various flags are reset, or Initial settings such as the start of counting of the main timer every 15 milliseconds, which is the control sampling period, are performed.

[0034] Then, TCL76 based on the detection signals from various sensors at M2 calculates a vehicle speed V or the like, this followed by learning correction at the neutral position [delta] _M and M3 of the steering shaft 83. The neutral position δ _M of the steering shaft 83 of the vehicle 82 is represented by EC
Since the initial value δ _{m (0)} is read every time the ignition key switch 75 is turned on because it is not stored in a memory (not shown) in the U15 or the TCL 76, when the vehicle 82 satisfies a straight traveling condition described later. Only the initial value δm ₍₀₎ is learned and corrected until the ignition key switch 75 is turned off.

Next, the TCL 76 detects the detection signals from the front wheel rotation sensors 66 and 97 and the rear wheel rotation sensors 80 and 8 at M4.
The target drive torque T _{OS in the} case where the slip control for regulating the drive torque of the engine 11 based on the detection signal from the control unit 1 is performed.
Is calculated, and a target of the engine 11 when the turning control for restricting the driving torque of the engine 11 based on the detection signals from the rear wheel rotation sensors 80 and 81 and the detection signal from the steering angle sensor 84 is performed at M5. The driving torque T _OC is calculated.

Then, at M6, the TCL 76 selects an optimum final target driving torque T _O from the target driving torques T _OS and T _OC by a method described later mainly in consideration of safety. Further, when the vehicle suddenly starts or when the road surface condition suddenly changes from a normal dry road to a frozen road, the actuator 41 is used.
The engine 1 can also be operated by fully closing the throttle valve 20 via the
Since 1 output reduction is likely not in time, to select a retard ratio for correcting the basic retardation amount p _B based at M7 slip amount s of the rate of change G _s of the front wheel 64, 65.

Next, at M8, the ECU 15 performs differential restraint torque control for setting the differential restraint torque _TF of the restraint torque adjusting clutch 89 based on the detection signals from the front wheel rotation sensors 66 and 97, and the like. while outputting the data relating to retard the rate of the final target driving torque T _O and basic retardation amount p _B in ECU15 at M9, differential restraining torque T
_The energization amount corresponding to _F is read.

When the driver operates a manual switch (not shown) to perform slip control or turning control, the ECU 15 sets the driving torque of the engine 11 to the final target driving torque T _O. controlling the duty ratio of the pair of torque control solenoid valve 51 and 56, further on the basis of the data relating to retard the rate of the basic retard amount p _B, the ECU
It calculates a target retardation amount p _O in the 15, while delaying the target retard amount p _O optionally the ignition timing P, restraining torque adjusting clutch energization amount corresponding to the differential restraint torque T _F from ECU15 89, so that the vehicle 82 can run safely without difficulty.

If the driver does not desire slip control or turning control by operating a manual switch (not shown), the ECU 15 sets the pair of solenoid valves 51 and 5 for torque control.
As a result of setting the duty ratio 6 to the 0% side, the vehicle 82 enters a normal driving state corresponding to the driver's depression amount of the accelerator pedal 31. In this case, in this embodiment, the differential restraint torque control is linked to the slip control, so that the differential restraint torque _{TF of} the restraint torque adjusting clutch 89 becomes 0, and the differential device 90 functions as it is. Will be done.

As described above, the driving torque of the engine 11 is set to M1
At 0, control is performed until the countdown every 15 milliseconds, which is the sampling period of the main timer, is completed.
The steps from 2 to M11 are repeated until the ignition key switch 75 is turned off.

When the turning control is performed in step M5 to calculate the target driving torque T _OC of the engine 11,
The TCL 76 calculates the vehicle speed V by the following equation (1) based on the detection signals of the pair of rear wheel rotation sensors 80 and 81 and calculates the vehicle speed V based on the detection signals from the steering angle sensor 84.
5 is calculated by the following equation (2), and the target lateral acceleration G _YO of the vehicle 82 at this time is obtained by the following equation (3). V = (V _RL + V _RR ) / 2 (1) δ = δ _H / ρ _H (2) G _YO = δ / ω · (A + 1 / V ² ) (3) [rho _H steering gear transmission ratio, omega is the wheel base of the vehicle 82, a is a stability factor of the vehicle 82 to be described later.

As is apparent from the equation (3), the vehicle 82
When the toe-in adjustment of the front wheels 64 and 65 is performed during maintenance of the vehicle, or due to secular change such as wear of a steering gear (not shown),
When the neutral position [delta] _M of the steering shaft 83 would change, deviation between the actual steering angle [delta] of the front wheels 64, 65 pivot the position [delta] _m and the steering wheel of the steering shaft 83 is generated. As a result, the vehicle 8
The second target lateral acceleration G _YO may not be able to be accurately calculated, making it difficult to perform good turning control. In addition, in the present invention, at the time of the slip control in the step of M4, a cornering drag correction unit described later
And correcting the reference driving torque of the engine 11 based on the turning angle [delta] _H of the steering shaft 83, the road surface μ estimating means to be described later similarly are estimated road surface μ on the basis of the turning angle [delta] _H of the steering shaft 83 For this reason, there is a possibility that the slip control and the differential constraint torque control cannot be performed well. Therefore, the neutral position δ _M of the steering shaft 83 needs to be learned and corrected in the step M3.

As shown in FIGS. 7, 8, and 9, which show the procedure for learning and correcting the neutral position δ _M of the steering shaft 83, T
The CL 76 determines at H1 whether the turning control flag F _C is set. When it is determined in step H1 that the vehicle 82 is under turning control,
It changes suddenly by output of the engine 11 learns correct neutral position [delta] _M of the steering shaft 83, there is a fear such that worsen the ride comfort, does not perform the neutral position [delta] _M of the learning correction of the steering shaft 83.

On the other hand, if it is determined that the vehicle 82 in step H1 is not in the turning control, since not occur inconvenience even if the neutral position [delta] _M of the learning correction of the steering shaft 83,
TCL76 is based on the detection signal from the rear wheel rotation sensor 80, 81 is calculated by the vehicle speed V (1) Equation for learning and turning control to be described later in the neutral position [delta] _M in H2. Next, the TCL 76 calculates the difference between the rear wheel speeds V _RL and V _RR (hereinafter referred to as a rear wheel speed difference) | V _RL −V _RR | at H3, and then the TCL 76 calculates the steering shaft at H4. Reference position sensor 8
6 depending on whether the learning correction of the neutral position [delta] _M is performed in the state in which the reference position [delta] _N of the steering shaft 83 is detected, i.e. the steering angle neutral position in a state where the reference position [delta] _N of the steering shaft 83 is detected It is determined whether or not the learned flag F _HN is set.

Immediately after the ignition key switch 75 is turned on, the steering angle neutral position learned flag F _HN is not set, that is, learning of the neutral position δ _M is the first time.
At H5, it is determined whether or not the steering shaft turning position δ _{m (n)} calculated this time is equal to the steering shaft turning position δ _{m (n-1)} calculated last time. At this time, it is desirable to set the turning detection resolution of the steering shaft 83 by the steering angle sensor 84 to, for example, about 5 degrees so as not to be affected by the hand shake of the driver or the like.

In the step H5, the steering shaft turning position δ _{m (n)} calculated this time is changed to the steering shaft turning position δ calculated last time.
When it is determined that the vehicle speed V is equal to _{m (n-1),} it is determined at H6 whether the vehicle speed V is greater than a preset threshold value _VA . This operation, when the vehicle 82 is not a certain amount of high-speed, wheel speed difference after accompanying steering | V _RL -V _RR | are those necessary for the like can not be detected, the running characteristic of the threshold V _A vehicle 82 The distance is set as appropriate, for example, at 10 km / h by experiments based on the above.

[0047] When it is determined that the vehicle speed V is greater than or equal to the threshold V _A at H6 step, the TCL76 H7
Determining previously set, or smaller or not than such threshold value V _X of example hourly 0.3km, i.e. whether the vehicle 82 is running straight | V _RL -V _RR | rear wheel speed difference at. Here, not to the threshold value V _X per hour 0km left and right rear wheels 7
If the tire pressures at 8,79 are not equal, the vehicle 82
Although the vehicle is in a straight running state, a pair of left and right rear wheels 7
This is in order to avoid that the vehicle 82 is not determined to be in the straight traveling state due to the difference in the peripheral velocities V _RL and V _{RR of} 8,79.

If the air pressures of the tires of the left and right rear wheels 78 and 79 are not equal, the rear wheel speed difference | V _RL -V _RR | tends to increase in proportion to the vehicle speed V. leave mapped to point to the _X in FIG. 10 for example, it may be read threshold V _X based on the vehicle speed V from the map.

In step H7, the rear wheel speed difference | V _RL −
V _RR | if is equal to or less than the threshold value V _X, the steering shaft reference position sensor 86 is a reference position of the steering shaft 83 at H8 [delta]
It is determined whether _N has been detected. And this H8
In the step, the steering shaft reference position sensor 86
And it detects the reference position [delta] _N, i.e., when the vehicle 82 is determined to be running straight begins a first count of the learning timer (not shown) incorporated in the TCL76 at H9.

Next, the TCL 76 determines in H10 whether or not 0.5 seconds have elapsed from the start of counting of the first learning timer, that is, whether or not the straight traveling state of the vehicle 82 has continued for 0.5 seconds. If 0.5 second has not elapsed from the start of counting by the first learning timer, the vehicle speed V is determined at H11.
Is larger than the threshold value _VA . This H1
If the vehicle speed V is determined to be greater than the threshold value V _A is at 1 in step, the rear wheel speed difference at H12 | V _RL -V _RR | is equal to or less than such threshold value V _B hourly 0.1km Is determined.
Rear wheel speed difference at this H12 step | V _RL -V _RR | is equal to or less than the threshold value V _B, i.e., if the vehicle 82 is determined to be running straight, shown incorporated in the TCL76 at H13 The second learning timer starts counting.

Then, at H14, it is determined whether or not 5 seconds have elapsed since the start of the counting of the second learning timer, ie, whether the vehicle 8
It is determined whether the straight traveling state of No. 2 has continued for 5 seconds, and if 5 seconds have not elapsed since the start of counting of the second learning timer, the process returns to the step of H2 and returns to the steps of H2 to H14. The operation up to is repeated.

At the step H8 in the middle of this repetitive operation, the steering shaft reference position sensor 86 detects the reference position δ _{N of the} steering shaft 83.
Is detected, the counting of the first learning timer is started in step H9, and 0.5 seconds have elapsed from the start of counting of the first learning timer in H10, that is, the vehicle If it is determined that the straight-ahead state of 82 has continued for 0.5 seconds, the steering angle neutral position learned flag F _HN in the state where the reference position δ _N of the steering shaft 83 is detected at H15 is set, and H16 Furthermore the steering angle neutral position learned flag F _H in a state where the reference position [delta] _N of the steering shaft 83 is not detected by the determines whether or not it is set. Also, if it is determined in step H14 that 5 seconds have elapsed since the start of counting of the second learning timer, the process shifts to step H16.

[0053] In the above operations, because they are not the steering angle neutral position learned flag F _H is set in a state that is not yet detected the reference position [delta] _N of the steering shaft 83, the reference position of the steering shaft 83 in steps of this H16 [delta] _N is is not set the steering angle neutral position learned flag F _H in a state that is not detected, i.e., when the learning of the neutral position [delta] _M in a state where the reference position [delta] _N of the steering shaft 83 is detected is a first In step H17, the current steering shaft turning position δ _{m (n)} is regarded as the neutral position δ _{M (n)} of the new steering shaft 83, and this is read into the memory in the TCL 76 and the reference position δ of the steering shaft 83 is determined. _N sets the steering angle neutral position learned flag F _H in a state that is not detected.

After the new neutral position δ _{M (n)} of the steering shaft 83 is set in this way, the neutral position δ
While calculating the turning angle [delta] _H of the steering shaft 83 and _M as a reference, a count of the learning timer is cleared at H18,
The steering angle neutral position learning is performed again.

If it is determined in step H5 that the currently calculated steering shaft turning position δm _(n) is not equal to the previously calculated steering shaft turning position δm _(n-1) , or if H11 is determined. The vehicle speed V is not equal to or higher than the threshold value _{VA in} the step
Wheel speed difference after calculated by the second step | V _RL -V _RR | when it is determined that there is no reliable, or the rear wheel differential velocity determined in step H12 | V _RL -V _RR | is threshold V _B If it is determined that the vehicle 82 is not in the straight traveling state, the flow shifts to step H18.

In step H7, the rear wheel speed difference | V
If you are determined to be larger than the threshold value V _X, | _RL -V _RR
If the steering shaft reference position sensor 86 at H8 step is determined not to detect the reference position [delta] _N of the steering shaft 83, and clears the count of the first learning timer at H19, the H11 Move to step,
If the vehicle speed V is determined to be equal to or lower than the threshold value _{VA in} the step (i), it is not possible to determine that the vehicle 82 is in a straight-ahead state.

On the other hand, in step H4, the steering shaft 83
If the steering angle neutral position learned flag F _HN in the state where the reference position δ _N is detected is set, that is, if it is determined that the learning of the neutral position δ _M is the second time or later, at H20 The steering shaft reference position sensor 86 determines the reference position δ of the steering shaft 83.
It is determined whether _N has been detected. And this H2
At step 0, the steering shaft reference position sensor 86
When the third reference position [delta] _N is determined to be detected,
At H21, it is determined whether or not the vehicle speed V is greater than a preset threshold value _VA .

At the step H21, the vehicle speed V becomes equal to the threshold value V.
If it is determined that the value is equal to or greater than _A ,
V _RL -V _RR | | whether the smaller than the threshold value V _X, i.e. the vehicle 82 determines whether the running straight rear wheel speed difference at. Then, the rear wheel speed difference is determined in step H22 | V _RL -V _RR | If it is determined that less than the threshold value V _X, currently calculated steering shaft turning position δ _{m (n)} is the last time at H23 It is determined whether the calculated value is equal to the calculated steering shaft turning position Δm _(n-1) . If it is determined in step H23 that the currently calculated steering shaft turning position δm _(n) is _equal to the previously calculated steering shaft turning position δm _(n-1) , then in H24 the first shaft turning position δm _(n-1) is determined. The learning timer starts counting.

Next, the TCL 76 determines in H25 whether or not 0.5 seconds have elapsed from the start of counting of the first learning timer, that is, whether or not the straight traveling state of the vehicle 82 has continued for 0.5 seconds. If 0.5 second has not elapsed from the start of counting by the first learning timer, the process returns to the step H2, and the steps H2 to H4 and H20 to H25 are repeated. Conversely, if it is determined in step H25 that 0.5 seconds have elapsed from the start of the count of the first learning timer, the process proceeds to step H16.

[0060] Incidentally, the steering shaft reference position sensor 86 is determined in step H20 is or if it is determined that not detected the reference position [delta] _N of the steering shaft 83, with the vehicle speed V is a threshold value V _A or in step H21 is That is, the rear wheel speed difference | V _RL −V _RR | calculated in step H22 is not reliable, or the rear wheel speed difference | V is calculated in step H22.
If you are determined to be larger than the threshold value V _X, | _RL -V _RR
Steering axis turning position δ calculated this time in step H23
_{m (n)} is the case where it is determined not equal to the steering shaft pivoted position previously calculated δ _{m (n-1)} are all the process proceeds to step of the H18.

[0061] Step at the steering angle neutral position learned flag F _H of the H16 is set, i.e., a neutral position δ
If it is determined that learning of _M is the second time or later, TCL7
6, the current steering shaft turning position δm _(n) is _equal to the previous neutral position δM _(n-1) of the steering shaft 83 at H26, that is, δm _(n) = δM _(n-1) . Determine if there is. If it is determined that the current steering shaft turning position δ _{m (n)} is _equal to the previous neutral position δ _{M (n-1)} of the steering shaft 83, the process directly proceeds to step H18, and the next steering angle neutral position is determined. Position learning is performed.

At the step H26, the current steering shaft turning position δm _(n) is not equal to the previous neutral position δM _(n-1) of the steering shaft 83 due to play in the steering system or the like. If it is determined, is not determined current steering shaft turning position [delta] _m to _(n) as a neutral position of the new steering shaft 83 [delta] _{M (n)} in the present embodiment, correction absolute value of the difference between these values preset If the difference is not less than the limit amount Δδ, the neutral position δ _M of the new steering shaft 83 is obtained by subtracting or adding the correction limit amount Δδ to the previous steering shaft turning position δ _{m (n-1)} . _(n) and this is TCL7
6 to be read into the memory.

That is, the TCL 76 changes the current steering shaft turning position δ _{m (n)} from the previous neutral position δ of the steering shaft 83 at H27.
_The value obtained by subtracting _{M (n-1)} is a preset negative correction limit amount-Δ
It is determined whether it is smaller than δ. And this H27
When it is determined that the value subtracted in the step is smaller than the negative correction limit amount -Δδ, the neutral position δ _{M (n)} of the new steering shaft 83 is changed to the neutral position of the previous steering shaft 83 at H28. From the position δ _{M (n-1)} and the negative correction limit amount −Δδ, change δ _{M (n)} = δ _{M (n-1)} −Δδ, and the learning correction amount per time is unconditionally negative. Care is taken not to become too large.

Accordingly, even if an abnormal detection signal is output from the steering angle sensor 84 for some reason,
Neutral position [delta] _M of the steering shaft 83 is not in the sudden change, it is possible to cope with the abnormality quickly.

On the other hand, if it is determined that the value subtracted in step H27 is larger than the negative correction limit amount -Δδ, the current steering shaft turning position δ _{m (n)} is determined in H29 from the previous steering shaft turning position δm _(n). It is determined whether or not the value obtained by subtracting the neutral position δM _(n-1) of the 83 is larger than the positive correction limit amount Δδ. The value subtracted in the step of H29 is a positive correction limit Δ
If it is determined that the neutral position is larger than δ, the neutral position δ _{M (n)} of the new steering shaft 83 is set to the neutral position δ _{M (n−1)} of the previous steering shaft 83 and the positive correction limit Δδ at H30. From this, δM _(n) = δM _(n-1) + Δδ is changed so that the amount of learning correction per time is not unconditionally increased to the positive side.

Thus, even if an abnormal detection signal is output from the steering angle sensor 84 for some reason,
Neutral position [delta] _M of the steering shaft 83 is not in the sudden change, it is possible to cope with the abnormality quickly.

However, if it is determined that the value subtracted in step H29 is smaller than the positive correction limit amount Δδ,
At H31, the current steering shaft turning position δm _(n) is read out as it is as the new neutral position δM _(n) of the steering shaft 83.

As described above, in the present embodiment, when learning and correcting the neutral position δ _M of the steering shaft 83, the rear wheel speed difference | V _RL -V _RR |
In addition to using only the neutral position δ _M of the steering shaft 83 within a relatively short time after the vehicle 82 starts, a method of using the detection signal from the steering shaft reference position sensor 86 in addition to using the neutral position δ _M is used. In addition, the steering shaft reference position sensor 86
There rear wheel speed difference also failed for some reason | V _RL -V _RR | only neutral position [delta] _M of the steering shaft 83 can learn corrected, it is excellent in safety.

Therefore, when the stopped vehicle 82 starts with the front wheels 64 and 65 kept in the turning state, as shown in FIG. 11 showing an example of a change state of the neutral position δ _M of the steering shaft 83 at this time. when learning control neutral position [delta] _M of the steering shaft 83 is for the first time, the correction amount from the initial value of the steering shaft pivoted position at step M1 of the aforementioned [delta] _{m (0)} is a very large, the second time The subsequent neutral position δ _M of the steering shaft 83 is H1
The state is suppressed by the operation in steps H7 and H19.

In this manner, the neutral position δ _{M of the} steering shaft 83
After learning correction, the target drive torque T _OS for performing slip control for regulating the drive torque of the engine 11 based on the detection signal from the front wheel rotation sensor 66 and the detection signals from the rear wheel rotation sensors 80 and 81 is calculated. Calculate.

By the way, the friction coefficient change rate of the vehicle speed V applied to the vehicle 82 of the tire and the road surface so (hereinafter, referred to as longitudinal acceleration) can be considered to be equivalent to G _X, in this embodiment this was calculated based on longitudinal acceleration G _X to the detection signal from the rear wheel rotation sensor 80, 81, a reference driving torque T _B of the engine 11 corresponding to the maximum value of the longitudinal acceleration G _X, detected from the front wheel rotation sensor 66 The target drive torque T _OS is calculated based on a deviation (hereinafter, referred to as a slip amount) s between the front wheel speed V _F and the target front wheel speed V _FO corresponding to the vehicle speed V.

As shown in FIG. 12 and FIG. 13 showing calculation blocks for calculating the target driving torque T _OS of the engine 11, first, the TCL 76 detects the vehicle speed V _S for slip control from the rear wheel rotation sensors 80 and 81. In this embodiment, the lower vehicle speed selector 101 uses the smaller one of the two rear wheel speeds V _RL and V _RR as the first vehicle speed V _S for slip control. The high vehicle speed selection unit 102 selects the larger one of the two rear wheel speeds V _RL and V _RR as the second vehicle speed V _S for slip control, and then selects the second vehicle speed V _S by the changeover switch 103. Selection units 101 and 102
Which of the outputs is to be taken is further selected.

In this embodiment, the first vehicle speed V _S selected by the low vehicle speed selection unit 101 is the two rear wheel speeds V _RL , V _RL
The smaller value _VL of _RR is multiplied by a weighting coefficient K _V corresponding to the vehicle speed V calculated by the above equation (1).
Multiplied by which the two rear wheels speed V _RL, seeking by adding the obtained by multiplying at multiplier 105 the larger value V _H of the V _RR and (1-K _V) I have.

That is, the engine 11 is actually controlled by the slip control.
In the state where the driving torque of the vehicle is reduced, that is, the slip control flag F _S is set, the smaller value of the two rear wheel speeds V _RL and V _RR is selected as the vehicle speed V _S by the changeover switch 103. and a state in which the drive torque is not reduced in the engine 11 even if the driver wants to slip control, that is in the slip control flag F _S is reset state, after the two wheel speed V _RL, among V _RR Is selected as the vehicle speed V _S.

This is because it is difficult to make a transition from a state where the driving torque of the engine 11 is not reduced to a state where the driving torque of the engine 11 is reduced, and it is also difficult to make a transition in the opposite case. For example, when the smaller one of the two rear wheel speeds V _RL , V _RR during the turning of the vehicle 82 is selected as the vehicle speed V _S , the slip occurs even though the front wheels 64, 65 do not slip. Is determined to occur, and the driving torque of the engine 11 is temporarily reduced in consideration of the traveling safety of the vehicle 82 in order to avoid such a problem that the driving torque of the engine 11 is reduced. This is because consideration has been given to keep this state.

When the vehicle speed V _S is calculated by the low vehicle speed selection unit 101, the smaller value V _L of the two rear wheel speeds V _RL and V _RR is multiplied by a weighting coefficient K _V to the multiplication unit 104. multiplying Te, and this and the two rear wheels speed V _RL, to adding to those obtained by multiplying at multiplier 105 the larger value V _H of the V _RR and (1-K _V), for example an intersection When traveling on a circuit with a small radius of curvature, such as a right or left turn at the front wheel speed, the front wheel speeds V _FL , V _FR
(V _FL + V _FR ) / 2 and two rear wheel speeds V _RL , V _RR
Is significantly different from the smaller value _{VL of the above} , the correction amount of the driving torque by the feedback becomes too large, and the acceleration of the vehicle 82 may be impaired.

In this embodiment, the weighting coefficient K
_V is read from a map as shown in FIG. 14 based on the vehicle speed V of the above equation (1), which is the average value of the rear wheel speeds V _RL and V _RR .

[0078] While calculates the vehicle speed V _S longitudinal acceleration G _X based on the slip control is calculated in this manner, first time calculated vehicle speed V _{S (n)} and vehicle speed V calculated before once
_{From S (n−1)} , the current longitudinal acceleration G _{X (n)} of the vehicle 82 is calculated by the differential operation unit 106 as in the following equation. G _{X (n)} = {V _{s (n)} −V _{s (n-1)} } / 3.6 · Δt · g where Δt is 15 milliseconds, which is the sampling period of this control, and g is the gravitational acceleration. .

When the calculated longitudinal acceleration G _{X (n)} is 0.6 g or more, the maximum value of the longitudinal acceleration G _{X (n)} is set to 0 in consideration of safety against calculation errors and the like. .6
g so that the longitudinal acceleration G _{X (n)} is clipped to 0.6 g by the clip unit 107. Further, the filter unit 1
At 08, a corrected longitudinal acceleration G _XF is calculated by performing filter processing for noise removal.

In this filter processing, the longitudinal acceleration G _{X (n)} of the vehicle 82 can be regarded as being equivalent to the coefficient of friction between the tire and the road surface.
_{Even if} the maximum value of _{X (n)} changes and the slip ratio S of the tire is likely to deviate from the target slip ratio S _O corresponding to the maximum value of the coefficient of friction between the tire and the road surface or the vicinity thereof, the slip of the tire may be reduced. The longitudinal acceleration G _{X (n) is} set so that the rate S is maintained at or less than the target slip rate S _O corresponding to the maximum value of the coefficient of friction between the tire and the road surface.
Is corrected, and is specifically performed as follows.

When the current longitudinal acceleration G _{X (n)} is _{equal to} or greater than the previous corrected longitudinal acceleration G _{XF (n−1)} subjected to the filtering process, that is, when the vehicle 82 continues to accelerate, the current longitudinal acceleration G _{X (n)} is _{XF (n) is set} to _{GXF (n)} = 28 · {GX _(n) −GXF _(n-1) } / 256, noise is removed by delay processing, and the corrected longitudinal acceleration _{GXF (n)} is compared. The vehicle is made to follow the longitudinal acceleration G _{X (n)} as quickly as possible.

When the current longitudinal acceleration G _{X (n)} is less than the previous corrected longitudinal acceleration G _{XF (n-1)} , that is, when the vehicle 82 is not accelerating too much, the following processing is performed for each sampling period Δt of the main timer. I do.

When the slip control flag F _S is not set, that is, when the driving torque of the engine 11 is not reduced by the slip control, the vehicle 82 is decelerating, so that G _{XF (n)} = G _{XF (n -1)} -0.002, thereby suppressing a decrease in the corrected longitudinal acceleration G _{XF (n)} and ensuring responsiveness to a driver's request for acceleration of the vehicle 82.

Also, the vehicle 82 is decelerating even when the slip amount s is positive, that is, when the front wheels 64 and 65 are slightly slipping while the driving torque of the engine 11 is reduced by the slip control. Since there is no problem in safety, G _{XF (n)} = G _{XF (n−1)} −0.002 to suppress the decrease in the corrected longitudinal acceleration G _XF and reduce the responsiveness to the driver's request for acceleration of the vehicle 82. Is secured.

Further, when the slip amount s of the front wheels 64 and 65 is negative while the driving torque of the engine 11 is reduced by the slip control, that is, when the vehicle 82 is decelerating, the maximum value of the corrected longitudinal acceleration G _XF is set to Holding and vehicle 8 by driver
2 to ensure responsiveness to acceleration requests.

Similarly, during the shift-up of the hydraulic automatic transmission 13 by the hydraulic control device 16 in a state where the driving torque of the engine 11 is reduced by the slip control, it is necessary to secure a feeling of acceleration for the driver. The maximum value of the corrected longitudinal acceleration G _XF is held.

The corrected longitudinal acceleration G _XF from which noise has been removed by the filter unit 108 is converted into a torque by the torque converting unit 109. The value calculated by the torque converting unit 109 is, of course, However, in order to prevent a calculation error in the clip unit 110, the value is clipped to 0 or more, and then the running resistance calculation unit 1
The running resistance T _R calculated in 11 adds at adding unit 112, the cornering drag correction torque T _C calculated by the cornering drag correction amount calculating unit 113 further based on the detection signal from the steering angle sensor 84 Adder 114
It was added by, for calculating a reference driving torque T _B expressed by the following equations (4). _{T B = G FO · W b} · r + T R + T C ··· (4) where, W _b is the body weight, r is an effective radius of the front wheel 64, 65.

[0088] The running resistance T _R is can be calculated as a function of the vehicle speed V, the in this embodiment are determined from the map as shown in FIG. 15. In this case, since the running resistance T _R is different between flat road and an uphill road, in the map drawing, and uphill road shown by a flat road and two-dot chain line indicated by the solid line is written, incorporated in the vehicle 82 One of them is selected based on a detection signal from a tilt sensor (not shown).
It is also possible to set _R.

In this embodiment, the cornering drag correction torque T _C is obtained from a map as shown in FIG. 16, whereby the engine 11 approximates the actual running state.
It can be set in the reference driving torque T _B, since the reference driving torque T _B of the turning immediately after the engine 11 is in the large acceleration feeling of the vehicle 82 after exiting the turning path is improved.

[0090] Incidentally, the (4) with respect to the reference driving torque T _B is calculated by the equation, variable clip portion 11 in this embodiment
By setting the lower limit value at 5, the final correction torque T _PID which will be described later from the reference driving torque T _B subtracting unit 11
The problem that the value subtracted in step 6 becomes negative is prevented. The lower limit of the reference driving torque T _B, as shown in the map as shown in FIG. 17, so that decrease stepwise in accordance with the time elapsed from the start of the slip control.

On the other hand, TCL 76 is a front wheel rotation sensor 66,
The average value (V _FL + V _FR ) / 2 of the left and right front wheel speeds V _FL and V _FR , which is the actual front wheel speed V _F, is calculated based on the detection signal from the ECU 97 as described above. Target front wheel speed V _FO set based on V _F and vehicle speed V _S for slip control
Front wheel speed V _FS for correction torque calculation set based on
The target drive torque T _OS of the engine 11 is calculated by performing feedback control of the reference drive torque T _B using the slip amount s which is a deviation from the reference drive torque T _OS .

By the way, in order to effectively use the driving torque generated in the engine 11 when the vehicle 82 is accelerating, it is necessary to use the driving torque shown in FIG.
As shown by the solid line in the middle, the slip ratio S of the tires of the running front wheels 64 and 65 is smaller at or near the target slip ratio S _O corresponding to the maximum value of the coefficient of friction between the tire and the road surface. It is desirable to adjust the values so as to avoid energy loss and not to impair the steering performance and acceleration performance of the vehicle 82.

[0093] Here, the slip ratio S of the tire is _{S = (V F -V) /} V, the target slip rate S _O, depending on the condition of the road surface 0.
It is known that it swings in the range of about 1 to 0.25.
Therefore, it is desirable that a slip amount s of about 10% with respect to the road surface is generated in the front wheels 64 and 65 as the driving wheels while the vehicle 82 is traveling. In consideration of the above points, the target front wheel speed _VFO is set by the multiplication unit 117 according to the following equation. V _FO = 1.1 · V

The TCL 76 has an acceleration correction unit 118
At read slip correction amount V _K corresponding to corrected longitudinal acceleration G _XF previously described from such map is shown in Figure 19, this is added to the reference torque calculation target front wheel speed V _FO in addition unit 119. Although the slip correction amount V _K has a tendency to increase stepwise as the value of the corrected longitudinal acceleration G _XF increases, in this embodiment, this map is created based on a running test or the like. I have.

As a result, the target front wheel speed V _FS for calculating the correction torque is increased, and the slip ratio S during acceleration becomes a smaller value at or near the target slip ratio S _O indicated by the solid line in FIG. Is set to

On the other hand, the relationship between the coefficient of friction between the tire and the road surface during turning and the slip ratio S of the tire is shown in FIG.
As shown by the one-dot chain line therein, the tire slip rate at which the maximum value of the friction coefficient between the tire and the road surface during turning is:
It can be seen that the target slip ratio S _{O of the} tire, which is the maximum value of the coefficient of friction between the tire and the road surface while traveling straight, is considerably smaller. Therefore, it is desirable to set the target front wheel speed _VFO smaller than when the vehicle 82 is traveling straight so that the vehicle 82 can smoothly turn when the vehicle 82 is turning.

Therefore, the turning correction unit 120 reads the slip correction amount V _KC corresponding to the target lateral acceleration G _YO from the map shown by the solid line in FIG.
_Is subtracted from the target front wheel speed _VFO for calculating the reference torque. However, since the turning angle δ _H of the steering shaft 83 is not reliable until the neutral position δ _M of the first steering shaft 83 is learned after the first operation of turning on the ignition key switch 75, the rear wheel speed V _The slip correction amount V _KC is read from a map shown by a broken line in FIG. 20 based on the lateral acceleration G _Y actually acting on the vehicle 82 by _RL and V _RR .

By the way, the target lateral acceleration G _YO is obtained by calculating the steering angle δ by the above equation (2) based on the detection signal from the steering angle sensor 84, and by using the steering angle δ by the above equation (3). At the same time, the neutral position δ _M of the steering shaft 83 is learned and corrected.

Therefore, when an abnormality occurs in the steering angle sensor 84 or the steering shaft reference position sensor 86, the target lateral acceleration G _YO
May be completely wrong. Therefore, if an abnormality occurs in the steering angle sensor 84 or the like, the rear wheel speed difference |
Using V _RL −V _RR |, the actual lateral acceleration G _Y occurring in the vehicle 82 is calculated, and this is used instead of the target lateral acceleration G _YO .

More specifically, the actual lateral acceleration G _Y is calculated from the rear wheel speed difference | V _RL −V _RR | and the vehicle speed V by the lateral acceleration calculator 122 incorporated in the TCL 76 by the following equation (5). And the corrected lateral acceleration G _{YF obtained} by _performing noise removal processing on the noise in the filter unit 123 is used. G _Y = | V _RL −V _RR | · V / 3.6 ² · b · g (5) where b is the tread of the rear wheels 78 and 79, and the filter unit 123 calculates the lateral width calculated this time. From the acceleration G _{Y (n)} and the previously calculated corrected lateral acceleration G _{YF (n−1)} , the current corrected lateral acceleration G _{YF (n)} is subjected to low-pass processing by digital calculation represented by the following equation. G _{YF (n)} = {20 · {G _{Y (n)} −G _{YF (n-1)} } / 256

Whether an abnormality has occurred in the steering angle sensor 84 or the steering shaft reference position sensor 86 is determined, for example, by referring to FIG.
Can be detected by the TCL 76 by the disconnection detection circuit shown in FIG. That is, the outputs of the steering angle sensor 84 and the steering shaft reference position sensor 86 are pulled up by the resistor R and grounded by the capacitor C, and the outputs are directly used as T
While inputting to the A0 terminal of CL76 for various controls,
The signal is input to the A1 terminal through the comparator 88.
3. The negative terminal of the comparator 88 is set to 4.
When a specified value of 5 volts is applied and the steering angle sensor 84 is disconnected, the input voltage of the A0 terminal exceeds the specified value, the comparator 88 is turned on, and the input voltage of the A1 terminal continuously becomes high level H. . Therefore, if the input voltage of the A1 terminal is at a high level H for a predetermined time, for example, 2 seconds, the program of the TCL 76 is determined so that disconnection is determined and the occurrence of abnormality of the steering angle sensor 84 or the steering shaft reference position sensor 86 is detected. It has been set.

In the above-described embodiment, the abnormality of the steering angle sensor 84 and the like is detected by hardware, but the abnormality can be naturally detected by software.

For example, as shown in FIG. 22, which shows an example of a procedure for detecting this abnormality, the TCL 76 first uses W1 in FIG.
The abnormality is determined by the disconnection detection shown in FIG. 1, and if it is determined that the abnormality is not abnormal, the front wheel rotation sensor 66 is set at W2.
Then, it is determined whether or not the rear wheel rotation sensors 80 and 81 are abnormal. In this step of W2, each rotation sensor 66, 8
When it is determined that there is no abnormality in 0 and 81, it is determined whether the steering shaft 83 has been turned in the same direction by one turn or more, for example, 400 degrees or more in W3. In the case where the steering shaft 83 is determined in step W3 it was judged steering over 400 degrees in the same direction, whether or not there is a signal indicating the reference position [delta] _N of the steering shaft 83 from the steering shaft reference position sensor 86 at W4 Judge.

Then, in the step of W4, the steering shaft 8
If it is determined that there is no signal indicating the third reference position [delta] _N, if the steering shaft reference position sensor 86 is normal, the signal indicating the reference position [delta] _N of the steering shaft 83 is supposed there is at least once, W4 It is determined that the steering angle sensor 84 is abnormal, and the abnormality occurrence flag _FW is set.

If it is determined in step W3 that the steering shaft 83 has not been steered in the same direction by more than 400 degrees,
Or when the signal indicating the reference position [delta] _N of the steering shaft 83 is determined that there from the steering shaft reference position sensor 86 at W4 step, whether done so learn the steering shaft neutral position [delta] _M at W6 That is, it is determined whether at least one of the two steering angle neutral position learned flags F _HN and F _H is set.

In the step of W6, the steering shaft 83
If the learning of the neutral position [delta] _M was determined that done so, the rear wheel speed difference at W7 | V _RL -V _RR |, for example, every hour.
The vehicle speed V is, for example, between 20 km / h and 60 km / h at W8, and the steering shaft 83 at this time is at W9.
The absolute value of the turning angle [delta] _H is, for example less than 10 degrees, i.e., when the vehicle 82 is determined to be turning at a certain speed, if the steering angle sensor 84 is functioning normally, the Since the absolute value of the turning angle δ _H should be 10 degrees or more, it is determined at W10 that the steering angle sensor 84 is abnormal.

The slip correction amount V _KC corresponding to the target lateral acceleration G _YO is considered to increase the turning of the steering wheel 85 of the driver. Therefore, in the region where the target lateral acceleration G _YO is small, the corrected lateral acceleration G K It is set smaller than the slip correction amount V _KC corresponding to _YF . In the region where the vehicle speed V is low, it is desirable to ensure the acceleration of the vehicle 82. Conversely, when the vehicle speed V is a certain speed or more, it is necessary to consider the ease of turning. The corrected slip correction amount V _KF is calculated by reading out from the map shown in FIG. 23 and multiplying the corrected slip correction amount V _KC by the correction coefficient corresponding to the vehicle speed V.

As a result, the target front wheel speed _VFO for calculating the correction torque decreases, and the slip ratio S at the time of turning becomes smaller than the target slip ratio S _O at the time of straight traveling.
Although the acceleration performance is slightly reduced, good turning performance is secured.

As shown in FIG. 24 showing the procedure for selecting the target lateral acceleration G _YO and the actual lateral acceleration G _Y , the TCL 7
Reference numeral 6 denotes a corrected lateral acceleration G from the filter unit 123 as a lateral acceleration for calculating the slip correction amount V _KC at T1.
Adopted _YF, it determines whether the slip control flag F _S is set at T2.

If it is determined in step T2 that the slip control flag F _S has been set, the corrected lateral acceleration G _YF is employed as it is. This is because when the lateral acceleration, which is a reference for determining the slip correction amount V _KC during the slip control, is changed from the corrected lateral acceleration G _YF to the target lateral acceleration G _YO , the slip correction amount V _KC greatly changes and the vehicle 82
Is likely to be disturbed.

If it is determined in step T2 that the slip control flag F _S has not been set, the program proceeds to T3.
It is determined whether or not one of the two steering angle neutral position learned flags F _HN and F _H is set. If it is determined that neither of the two steering angle neutral position learned flags F _HN and F _H has been set, the corrected lateral acceleration G _YF is employed as it is. Also, this T
If it is determined in step 3 that one of the two steering angle neutral position learned flags F _HN , F _H has been set, the lateral acceleration for calculating the slip correction amount V _KC at T4. _Is adopted as the target lateral acceleration _GYO .

As a result, the target front wheel speed _VFS for calculating the correction torque is given by the following equation. V _FS = V _FO + V _K -V _KF

[0113] Next, the detection signal and the actual front wheel speed V _F obtained by the filter processing for the purpose of such as noise removal from the deviation a is the slip amount between the correction torque calculation target front wheel speed V _FS of the front wheel rotation sensor 66 s is calculated by the subtraction unit 124. When the slip amount s is equal to or less than a negative set value, for example, -2.5 km / h or less, the clip unit 125 clips -2.5 km / h as the slip amount s. s is subjected to a proportional correction to be described later, and overcontrol in the proportional correction is prevented so that output hunting does not occur.

Further, the slip amount s before clip processing is subjected to integral correction using an integral constant ΔT _i described later, and further to differential correction to calculate a final corrected torque T _PID .

As the proportional correction, a basic correction amount is obtained by multiplying the slip amount s by a proportional coefficient K _P in a multiplication unit 126, and a gear ratio ρ _{m of the} hydraulic automatic transmission 13 is obtained in a multiplication unit 127. to obtain a proportional correction torque T _P by multiplying a preset correction coefficient [rho _KP by. Note that the proportional coefficient K _P
Are read from the map shown in FIG. 25 according to the slip amount s after the clip processing.

Further, in order to realize a correction corresponding to a gradual change in the slip amount s as the integral correction, a basic correction amount is calculated by an integration operation unit 128, and the correction amount is calculated by a multiplication unit 129. And the gear ratio ρ of the hydraulic automatic transmission 13
_The integral correction torque T _I is obtained by multiplying a predetermined correction coefficient ρ _KI based on _m . In this case, in this embodiment, a constant minute integral correction torque ΔT _I is integrated, and
When the slip amount s is positive every millisecond sampling period, the small integral correction torque ΔT _I is added, and when the slip amount s is negative, the small integral correction torque ΔT _I is subtracted.

However, the integrated correction torque T _I includes the vehicle speed V
26, the lower limit value T _IL as shown in the map of FIG. 26 is set according to the clipping process. When the vehicle 82 starts, particularly when it starts on an uphill, a large integral correction torque T _IL is set.
Securing the driving force of the engine 11 by exercising _I, from the vehicle speed V is increased after the start of the vehicle 82, since lack the stability of the control and reverse the correction is too large, the integral correction torque T _I is reduced Like that. Further, the upper limit on the integral correction torque T _I to enhance the convergence of control, for example, set the 0Kgm, integral correction torque T _I by the clipping process changes as shown in FIG. 27.

The proportional correction torque T _P and the integral correction torque T _I calculated in this way are added by the adder 130 to calculate the proportional integral correction torque T _PI .

The correction coefficients ρ _KP and ρ _KI are read from a map as shown in FIG. 28 which is set in advance in association with the speed ratio ρ _m of the hydraulic automatic transmission 13.

[0120] In the present embodiment calculates the change rate G _s of the slip amount s by differentiating unit 131, to which the differential coefficient K _D
Is multiplied by the multiplication unit 132 to calculate a basic correction amount for a sudden change in the slip amount s. And the upper limit value and the lower limit value are respectively set for the obtained values,
As differential correction torque T _D is not an extremely large value, performs a clip processing by the clip portion 133, to obtain a differential correction torque T _D. The clip portion 133, the wheel speed V _F during running of the vehicle 82, the V _RL, V _RR is such a traveling state of the road surface conditions and vehicle 82, it may become momentarily idle or locked state, like this 55kgm the upper limit with change ratio G _s of the slip amount s when becomes a positive or negative extremely large value, the response control diverges may be deteriorated, clips for example the lower limit to -55kgm In order to prevent the differential correction torque T _{D from} becoming an extremely large value.

Thereafter, the proportion is calculated by the adder 134.
Integral correction torque T_PIAnd differential correction torque T_DAnd
The final correction torque T obtained by this_PIDSubtraction unit 11
6, the above-mentioned reference driving torque T_B, Then multiply
The axles 89, 9 of the engine 11 and the front wheels 64, 65 at the part 135
By multiplying by the reciprocal of the total reduction ratio between 0 and
The target drive torque T for slip control shown in (6)_OSCalculate
I do. T_OS= (T_B-T_PID) / Ρ_m・ Ρ_d・ Ρ_T ... (6) where ρ_dIs the differential gear reduction ratio, ρ_TIs a torque converter
The hydraulic automatic transmission 13 changes the upshift.
When performing a high-speed operation, change
Ratio ρ_mIs output. In other words, hydraulic
In the case of an upshifting operation of the automatic transmission 13,
The speed ratio ρ on the high speed side at the time of output of the shift signal _mAdopt
As is evident from equation (6) above,
Dynamic torque T_OSIncreases and the engine 11 blows up
Therefore, the gearshift operation is completed after outputting the gearshift start signal.
For example, for 1.5 seconds, the target driving torque T_OSIs smaller than
Lower gear ratio ρ_mIs held, and shifting starts
1.5 seconds after the output of the signal
_mIs adopted. For the same reason, the hydraulic automatic transmission 1
In the case of the downshift gear shifting operation of No. 3, the shift signal is output.
Speed ratio ρ_mIs immediately adopted.

The target driving torque T calculated by the above equation (6)
_{Since the OS} should naturally be a positive value, the clipping unit 136 clips the target drive torque T _OS to 0 or more in order to prevent a calculation error and determines whether to start or end the slip control. The information on the target drive torque T _OS is output to the ECU 15 in accordance with the determination processing by the start / end determination section 137 of the above.

The start / end determination unit 137 includes the following (a) to (e)
Determines that the initiation of the slip control when satisfying all of the conditions shown in, switched so as to select the output from the low-speed selector 101 as a vehicle speed V _S for slip control with sets of slip control flag F _S The switch 103 is operated, and information on the target drive torque T _{OS is} transmitted to the ECU 1.
Output to 5, until the slip control flag F _S to determine the end of the slip control is reset, and this process is continued. (a) The driver operates a manual switch (not shown) to desire slip control. (b) The driving torque _Td requested by the driver is the minimum driving torque required to drive the vehicle 82, for example, 4 kgm.
That is all.

In this embodiment, the required driving torque T
the engine speed N _E which is calculated by the detection signal from the crank angle sensor 62 to _d, in Figure 29 which is set in advance on the basis of the accelerator opening theta _A calculated by the detection signal from the accelerator opening sensor 76 It is read from the map as shown. (c) The slip amount s is 2 km / h or more. (d) The change rate Gs of the slip amount _s is 0.2 g or more. (e) the actual front wheel acceleration G _F obtained by differentiating the time with the actual front wheel speed V _F of the differentiating unit 138 is not less than 0.2 g.

On the other hand, after the start / end judgment section 137 judges the start of the slip control, if any of the following conditions (f) and (g) is satisfied, it is judged that the slip control is ended. reset the slip control flag F _S and,
The changeover switch 1 stops transmission of the target drive torque T _{OS to} the ECU 15 and selects the output from the high vehicle speed selection unit 102 as the vehicle speed V _S for slip control.
Activate 03. (f) The target drive torque T _OS is equal to or greater than the required drive torque T _d , and the state in which the slip amount s is equal to or less than a constant value, for example, −2 km / h, has continued for a certain time, for example, 0.5 seconds or more. (g) The state in which the idle switch 68 has changed from off to on, that is, the state in which the driver has released the accelerator pedal 31 has continued for a fixed time, for example, 0.5 seconds or more.

The vehicle 82 is provided with a manual switch (not shown) for the driver to select the slip control. When the driver operates the manual switch to select the slip control, a description will be given below. Perform the slip control operation. In the present embodiment, the differential restraint torque control of the present invention is performed as a part of the slip control. Therefore, the differential restraint torque control described later is performed only during the slip control. .

FIG. 3 showing the flow of the slip control process.
As indicated by 0, the TCL 75 calculates the target drive torque T _OS by detecting and calculating the various data described above in S1, but this calculation is performed irrespective of the operation of the manual switch.

[0128] Next, first slip control flag F _S at S2 is determines whether it is set, because the first slip control flag F _S is not set, T
The CL 76 determines in S3 whether the slip amount s of the front wheels 64 and 65 is larger than a preset threshold value, for example, 2 km / h.

[0129] If it is determined that the slip amount s is determined in step S3 is greater than the per hour 2km, TCL76 determines whether the rate of change G _s of the slip amount s is greater than 0.2g at S4.

[0130] If the slip amount change rate G _s is determined in step S4 is determined to be larger than 0.2g, TCL76
In S5, it is determined whether or not the driver's required driving torque _Td is greater than the minimum driving torque required to drive the vehicle 82, for example, 4 kgm, that is, whether or not the driver intends to drive the vehicle 82. Is determined.

In the step S5, the required driving torque T
_d is greater than 4Kgm, i.e. when the driver determines that there is intention to drive the vehicle 82, sets in the slip control flag F _S at S6, whether the slip control flag F _S is set at S7 It is determined again whether or not it is.

If it is determined in step S7 that the slip control flag F _S is being set, then in step S8, the slip drive calculated in advance by the equation (6) as the target drive torque T _OS of the engine 11 is determined. The target drive torque T _OS for control is adopted.

If it is determined in step S7 that the slip control flag F _S has been reset, the TCL 76 outputs the maximum torque of the engine 11 as the target drive torque T _{OS in} step S9. As a result, the ECU 15 lowers the duty ratio of the torque control solenoid valves 51 and 56 to the 0% side, and as a result, the engine 11 generates a drive torque corresponding to the amount of depression of the accelerator pedal 31 by the driver.

In the step S3, the front wheels 64, 65
If the slip amount s of is determined to be smaller than the hourly 2km, or if the slip rate of change G _s was determined to be smaller than 0.2g at step S4, or S5 step at the required driving torque T _d of Is smaller than 4 kgm, the process directly proceeds to step S7, and the TCL 76 determines the target drive torque T in step S9.
The maximum torque of the engine 11 is output as _OS , and
As a result of the CU 15 reducing the duty ratio of the torque control solenoid valves 51 and 56 to the 0% side, the engine 11 generates a driving torque according to the amount of depression of the accelerator pedal 31 by the driver.

[0135] On the other hand, if the step in the slip control by flag F _S of the S2 is determined to have been set, hourly -2km less slip amount s of front wheels 64 and 65 is a threshold as described above in S10 and the required driving torque T _d is less target driving torque T _OS calculated in the S1 state determines whether or not to continue for 0.5 seconds or more.

[0136] Step in slip amount s is small and the requested driving torque T _d than 2km the target driving torque T _OS following hour state of S10 is continues for 0.5 seconds or more,
That driver determines that not already desired acceleration of the vehicle 82, to reset the slip control flag F _S at S11, the process proceeds to step S7.

[0137] The or slip amount s is determined in step S10 is greater than the per hour 2km, or the required driving torque T _d is not continued target driving torque T _OS following conditions than 0.5 seconds, i.e. the driver If it is determined that the vehicle 82 is desired to accelerate, the TCL 76 turns on the idle switch 68 in S12, that is, the fully closed state of the throttle valve 20 is set to 0.5.
It is determined whether or not it has continued for more than seconds.

[0138] idle switch 68 at this step S12 if it is determined to be turned on, since the driver is not depressing the accelerator pedal 31, to reset the slip control flag F _S proceeds to step S11 . Conversely, when it is determined that the idle switch 68 is off, the driver has depressed the accelerator pedal 31, and the process returns to step S7.

If the driver does not operate the manual switch for selecting the slip control, the TCL 76 calculates the target drive torque T _OS for the slip control as described above, and then performs the turning control. The target driving torque of the engine 11 is calculated.

[0140] Incidentally, the lateral acceleration G _Y is the rear wheel speed difference of the vehicle 82 | V _RL -V _RR | the utilizing (5) can be actually calculated by equation, a steering shaft turning angle [delta] _H by utilizing, since it becomes possible prediction value of the lateral acceleration G _Y acting on the vehicle 82 has the advantage of being able to perform quick control.

Therefore, in turning control of the vehicle 82,
The TCL 76 determines the vehicle 8 based on the steering shaft turning angle δ _H and the vehicle speed V.
2 of the target lateral acceleration G _YO is calculated by the equation (3), based on the vehicle longitudinal acceleration as the vehicle 82 is not an extreme under-steering, that is, the target longitudinal acceleration G _XO in the target lateral acceleration G _YO Set. Then, a target drive torque T _OC of the engine 11 corresponding to the target longitudinal acceleration G _XO is calculated.

FIG. 31 shows an operation block of this turning control.
As shown in FIG. 32 and FIG.
At 0, the vehicle speed V is calculated from the output of the pair of rear wheel rotation sensors 80 and 81 by the above equation (1), and the steering angle sensor 84 is calculated.
The steering angle δ of the front wheels 64 and 65 is calculated from the above equation (2) based on the detection signal from the above, and the target lateral acceleration G _YO of the vehicle 82 at this time is calculated by the target lateral acceleration calculating section 141 using the equation (3). It is calculated from: In this case, the region where the vehicle speed V is low, for example, 2
When the distance is 3 km or less, it is better to prohibit the turning control than to perform the turning control, because sufficient acceleration can be obtained when turning left or right at an intersection with heavy traffic, etc. In this embodiment, the correction coefficient multiplication unit 1
At 42, the target lateral acceleration G _YO is multiplied by a correction coefficient K _Y as shown in FIG.

By the way, in the state where the learning of the steering shaft neutral position δ _M has not been performed, it is problematic in terms of reliability to calculate the target lateral acceleration G _YO based on the steering angle δ from the equation (3). Therefore, until learning of the steering shaft neutral position δ _M is performed,
It is desirable not to start turning control. However, vehicle 8
In the case where the vehicle 82 travels on a curved road immediately after the start of traveling of the vehicle 2, the vehicle 82 requires turning control. However, since the learning start condition of the steering shaft neutral position δ _M is not easily satisfied,
There is a possibility that a problem that this turning control is not started may occur. Therefore, until the present embodiment is performed the learning of steering shaft neutral position [delta] _M, the at changeover switch 143 (5)
The turning control can be performed using the corrected lateral acceleration G _YF from the filter unit 123 based on the equation. In other words, when both of the two steering angle neutral position learned flags F _HN and F _H are reset, the modified lateral acceleration G _YF is adopted by the changeover switch 143 and the two steering angle neutral position learned flags F _HN, if at least one of the F _H is set, the target lateral acceleration G _YO from the correction coefficient multiplication unit 142 is selected by the changeover switch 143.

Further, the stability factor A described above is
As is well known, the value is determined by the configuration of the suspension system of the vehicle 82, the characteristics of the tires, the road surface condition, and the like. Specifically, the actual lateral acceleration G _Y generated in the vehicle 82 during a steady circular turn and the steering angle ratio δ _H / δ of the steering shaft 83 at this time are shown.
_HO (lateral acceleration G based on neutral position δ _M of steering shaft 83)
The turning angle δ _H of the steering shaft 83 during acceleration with respect to the turning angle δ _HO of the steering shaft 83 in an extremely low-speed running state where _Y is _close to 0.
The ratio is expressed as, for example, a slope of a tangent in a graph as shown in FIG. That is, in a region where the lateral acceleration G _Y is small and the vehicle speed V is not so high, the stability factor A is almost constant (A = 0.002).
However, when the lateral acceleration G _Y exceeds 0.6 g,
The stability factor A sharply increases, and the vehicle 82 exhibits an extremely strong understeering tendency.

As described above, FIG. 34 corresponding to a pavement road surface in a dry state (hereinafter referred to as a high μ road).
, The stability factor A is set to 0.0
02, the driving torque of the engine 11 is controlled such that the target lateral acceleration G _YO of the vehicle 82 calculated by the equation (3) is less than 0.6 g.

In the case of a slippery road surface such as a frozen road (hereinafter referred to as a low μ road), the stability factor A may be set to, for example, about 0.005. In this case, on the low μ road, the target lateral acceleration G _YO is larger than the actual lateral acceleration G _Y, so the target lateral acceleration G _YO is larger than a preset threshold value, for example, (G _YF −2). If the target lateral acceleration G _YO is larger than this threshold value, it is determined that the vehicle 82 is traveling on a low μ road, and turning control for the low μ road is performed as necessary. Good. Specifically, by adding 0.05 g to the corrected lateral acceleration G _YF calculated based on the above equation (5), it is determined whether or not the target lateral acceleration G _YO is larger than a preset threshold value, that is, a low μ road. in order to become a large value towards the target lateral acceleration G _YO than the actual lateral acceleration G _Y, the target lateral acceleration G _YO is determined whether greater than this threshold, the target lateral acceleration G _YO
Is larger than the threshold, it is determined that the vehicle 82 is traveling on a low μ road.

When the target lateral acceleration G _YO is calculated in this manner, the magnitude of the target lateral acceleration G _YO and the vehicle speed V _YO are calculated in advance.
The target longitudinal acceleration G _XO of the vehicle 82 set in accordance with the above is read out from the map as shown in FIG. 35 pre-stored in the TCL 76 by the target longitudinal acceleration calculating section 144, and the engine 11 corresponding to the target longitudinal acceleration G _XO is read out. Reference drive torque T
_B is calculated by the reference driving torque calculation unit 145 according to the following equation (7). T _B = (G _{X O} · W _b · r + T _L ) / ρ _m · ρ _d · ρ _T (7) where T _L is the resistance of the road surface obtained as a function of the lateral acceleration G _Y of the vehicle 82. The load-load torque is obtained from a map as shown in FIG. 36 in this embodiment.

Here, simply obtaining the target drive torque of the engine 11 from the steering shaft turning angle δ _H and the vehicle speed V does not reflect the driver's will at all, and gives the driver a better controllability of the vehicle 82. Dissatisfaction may remain. Therefore, it calculated required driving torque T _d of the engine 11 that the driver wants the depression amount of the accelerator pedal 31, the required driving torque T _d
It is desirable to set the target drive torque of the engine 11 in consideration of the above.

Therefore, in the present embodiment, the reference driving torque T _B
To determine the adoption rate, determine the correction reference driving torque by multiplying the weighting coefficients α to the reference driving torque T _B in the multiplication section 146. The weighting coefficient α is set empirically by turning the vehicle 82, but is set to 0.6 on a high μ road.
Use numerical values around the degree.

[0150] On the other hand, the view of the required driving torque T _d in which the driver wishes based on the accelerator opening theta _A detected by the engine speed N _E and an accelerator opening sensor 77 detected by the crank angle sensor 55 35, the multiplication unit 147 sets the correction required drive torque corresponding to the weighting coefficient α to the required drive torque _Td by (1
−α). For example, α =
If set to 0.6, adoption ratio of the reference driving torque T _B and the required driving torque T _d is 6: 4.

Therefore, the target drive torque T _OC of the engine 11 is calculated by the adder 148 according to the following equation (8). T _OC = α · T _B + (1−α) · T _d (8)

If the target drive torque T _OC of the engine 11 that is set every 15 milliseconds is very large, a shock occurs due to acceleration and deceleration of the vehicle 82, which leads to a reduction in ride comfort. Therefore, if the amount of increase or decrease in the target drive torque T _OC of the engine 11 becomes large enough to cause a decrease in the riding comfort of the vehicle 82, it is desirable to regulate the amount of increase or decrease in the target drive torque T _OC .

Therefore, in the present embodiment, the change amount clip unit 1
49, the absolute value | ΔT of the difference between the target drive torque T _{OC (n)} calculated this time and the target drive torque T _{OC (n-1)} calculated last time.
Is smaller than the increase / decrease allowable amount T _K , the calculated target drive torque T _{OC (n)} is used as it is.
The difference ΔT between the currently calculated target drive torque T _{OC (n)} and the previously calculated target drive torque T _{OC (n-1)} is a negative increase / decrease allowable amount T.
If not greater than _K , the current target drive torque T
_{OC (n)} is set by the following equation. T _{OC (n)} = T _{OC (n-1)} −T _K

That is, the previously calculated target drive torque T
_The amount of decrease in _{OC (n-1)} is regulated by the permissible increase / decrease amount T _K to reduce the deceleration shock accompanying the reduction in the driving torque of the engine 11. If the difference ΔT between the currently calculated target drive torque T _{OC (n)} and the previously calculated target drive torque T _{OC (n-1)} is equal to or greater than the permissible change amount T _K , the current target drive torque T _{OC (n)}
Is set by the following equation. T _{OC (n)} = T _{OC (n-1)} + T _K

That is, the target drive torque T calculated this time is
_If the difference ΔT between _{OC (n)} and the previously calculated target drive torque T _{OC (n-1)} exceeds the increase / decrease allowable amount T _K , the increase width with respect to the previously calculated target drive torque T _{OC (n-1)} Is regulated by the allowable increase / decrease amount T _K , and the acceleration shock accompanying the increase in the driving torque of the engine 11 is reduced.

The information on the target drive torque T _{OC is} stored in the ECU 15 according to the determination processing in the start / end determination section 150 for determining the start or end of the turning control.
Is output to

The start / end judgment section 150 is composed of the following (a) to
When all the conditions shown in (d) are satisfied, it is determined that the turning control is started, the turning control in-progress flag F _C is set, and information on the target drive torque T _OC is output to the ECU 15.
This processing is continued until the end of the turning control is determined and the turning control flag F _C is reset. (a) The target driving torque T _OC is a threshold value, for example, 2 kg from the required driving torque T _d.
Less than the value obtained by subtracting m. (b) The driver operates a manual switch (not shown) to request turning control. (c) The idle switch 68 is off. (d) The control system for turning is normal.

On the other hand, after the start / end determining section 150 determines the start of the turning control, if any of the following conditions (e) and (f) is satisfied, it is determined that the turning control has ended. To reset the turning control flag F _C
The transmission of the target drive torque T _OC for is stopped. (e) The target drive torque T _OS is _{equal to} or greater than the required drive torque T _d . (f) The control system for turning has an abnormality such as failure or disconnection.

By the way, the output voltage of the accelerator opening sensor 77 and the accelerator opening θ _A naturally have a certain proportional relationship, and when the accelerator opening θ _A is fully closed, the accelerator opening An accelerator opening sensor 77 is attached to the throttle body 21 so that the output voltage of the sensor 77 becomes, for example, 0.6 volt. However, the vehicle 82
When the accelerator opening sensor 77 is removed from the throttle body 21 for inspection and maintenance of the throttle body 21 and reassembly is performed, it is practically impossible to accurately return the accelerator opening sensor 77 to the original attached state. In addition, the position of the accelerator opening sensor 77 with respect to the throttle body 21 may be shifted due to aging or the like.

Accordingly, in the present embodiment, the fully closed position of the accelerator opening sensor 77 is learned and corrected, whereby the accelerator opening θ _A calculated based on the detection signal from the accelerator opening sensor 77 is obtained. Reliable.

As shown in FIG. 37 showing the learning procedure of the fully closed position of the accelerator opening sensor 77, after the idle switch 68 is turned on and the ignition key switch 75 is turned off from on, a certain time, for example, The output of the accelerator opening sensor 77 for two seconds is monitored, and the minimum value of the output of the accelerator opening sensor 77 during this period is determined by the accelerator opening θ.
_A is taken in as the fully closed position of _A , stored in a backup RAM (not shown) incorporated in the ECU 15,
Correcting the accelerator opening theta _A reference to the minimum value of the output of the accelerator opening sensor 77 until the next learning.

However, when the storage battery (not shown) mounted on the vehicle 82 is removed, the storage in the RAM is erased. In such a case, the learning procedure shown in FIGS. 38 and 39 is adopted. .

That is, the TCL 76 determines at A1 whether or not the fully closed value θ _AC of the accelerator opening θ _A is stored in the RAM. At step A1, the accelerator opening θ _{A is determined.}
If it is determined that the fully closed value θ _AC is not stored in the RAM, the initial value θ _{A (0)} is stored in the RAM at A2.

On the other hand, when it is determined in step A1 that the fully closed value θ _AC of the accelerator opening θ _A is stored in the RAM, the ignition key switch 75 is switched to A3.
It is determined whether or not is turned on. If it is determined in step A3 that the ignition key switch 75 has changed from the ON state to the OFF state, the count of a learning timer (not shown) is started in A4. And
After the start of the counting of the learning timer, it is determined at A5 whether or not the idle switch 68 is on.

If it is determined in step A5 that the idle switch 68 is in the OFF state, it is determined in A6 whether the count of the learning timer has reached a set value, for example, 2 seconds. The process returns to step A5. or,
If it is determined in step A5 that the idle switch 68 is on, the output of the accelerator opening sensor 77 is read at a predetermined cycle in A7, and the current accelerator opening θ _{A (n)} is read in A8. It is equal to or smaller than the minimum value theta _AL accelerator opening theta _a far.

[0166] Here, when it is determined that the accelerator opening degree this time θ _{A (n)} is greater than the minimum value theta _AL accelerator opening theta _A to date, the minimum accelerator opening theta _A far Value θ _AL
If the current accelerator opening θ _{A (n)} is determined to be smaller than the minimum value θ _{AL of the} previous accelerator opening θ _A , the current accelerator opening θ _A is determined at A9. update _a and _(n) as a new minimum value theta _AL. This operation is repeated in step A6 until the count of the learning timer reaches a set value, for example, 2 seconds.

When the count of the learning timer reaches the set value, the minimum value θ _AL of the accelerator opening θ _A is set to a predetermined clip value, for example, between 0.3 volt and 0.9 volt at A10. Is determined. Then, if the minimum value theta _AL of the accelerator opening theta _A is determined to be within the range of preset clip value, the initial value θ _{A (0)} of the accelerator opening theta _A at A11 or All The fully closed value θ of the accelerator opening θ _A obtained by the current learning is obtained by bringing the closed value θ _AC closer to a constant value, for example, 0.1 volt, in the direction of the minimum value θ _{AL.
AC (n)} . That is, the initial value θ of the accelerator opening θ _{A
If A (0)} or the fully closed value θ _AC is larger than the minimum value θ _AL , θ _{AC (n)} = θ _{AC (0)} −0.1 or θ _{AC (n)} = θ _{AC (n -1)} −0.1, and conversely, if the initial value θ _{A (0)} or the fully closed value θ _AC of the accelerator opening θ _A is larger than its minimum value θ _AL , θ _{AC (n)} = Θ _{AC (0)} +0.1 or θ _{AC (n)} = θ _{AC (n-1)} +0.1

In step A10, the accelerator opening θ
If it is determined that the minimum value theta _AL of _A is outside the scope of the preset clip value replaces the clip value of those who are out at A12 as the minimum value theta _AL accelerator opening theta _A, wherein The process proceeds to step A11 to perform learning correction of the fully closed value θ _AC of the accelerator opening θ _A.

As described above, the minimum value θ of the accelerator opening θ _A
By setting the upper limit value and the lower limit value to _AL, there is no risk of erroneous learning even when the accelerator opening sensor 77 fails, and by setting the learning correction amount per time to a constant value, noise Erroneous learning is not performed even for disturbances such as

In the above-described embodiment, the learning start timing of the fully closed value θ _AC of the accelerator opening sensor 77 is based on the time when the ignition key switch 75 is changed from the on state to the off state. When the ignition key switch 75 is in the ON state, it is detected that the driver has left the seat by using the seat pressure change or position displacement by the seating sensor. May be started.
When the door lock device (not shown) is operated from outside the vehicle 82 or the key entry system detects that the door lock device is operated, the fully closed value of the accelerator opening sensor 77 is detected. It is also possible to start learning of θ _AC . In addition, the position of the shift lever (not shown) of the hydraulic automatic transmission 13 is the neutral position or the parking position (neutral position in the case of a vehicle equipped with a manual transmission), the manual brake is operated, and The air conditioner is off,
That is, the learning process may be performed when the vehicle is not in the idle-up state.

The vehicle 82 is provided with a manual switch (not shown) for the driver to select the turning control. When the driver operates the manual switch to select the turning control, the following will be described. The operation of the turning control is performed.

As shown in FIGS. 40 and 41 showing the flow of control for determining the target drive torque T _OC for turning control, the target drive torque is obtained by detecting and calculating the various data described above at C1. T _OC is calculated, but this operation is performed independently of the operation of the manual switch.

[0173] Next, it is determined whether the vehicle 82 is whether turning control, i.e. turning control flag F _C is set at C2. Initially, not a turning control, the turning control flag F _C is determined to be reset, it is determined whether or not for example (T _d -2) or less at C3. That is, even when the vehicle 82 is traveling straight, the target drive torque T
_OC can be calculated, but its value is usually larger than the driver's required driving torque _Td . However, since the required driving torque T _d is generally small during turning of the vehicle 82, the target driving torque T _OC threshold (T _d -
2) The following conditions are determined as start conditions for turning control.

The reason why the threshold value is set to (T _d -2) is as a hysteresis for preventing control hunting.

If it is determined in step C3 that the target drive torque T _OC is equal to or less than the threshold value (T _d -2), the TCL 76
Determines at C4 whether the idle switch 68 is off.

[0176] Step at idle switch 68 is turned off in this C4, that is, when the accelerator pedal 31 is determined to have been depressed by the driver, the turning control flag F _C is set at C5. Next, at C6, it is determined whether at least one of the two steering angle neutral position learned flags F _HN and F _H has been set, that is, the steering angle sensor 84.
The authenticity of the detected steering angle δ is determined.

If it is determined in step C6 that at least one of the two steering angle neutral position learned flags F _HN and F _H has been set, then in step C7 the turning control flag F _{C is determined.}
It is determined again whether or not is set.

[0178] In the above procedure, because the turning control flag F _C is set at C5 of the step, turning control flag F _C is a step of C7 is judged to be set, the previous at C8 The calculated value, that is, the target driving torque T _{OC in} the step of C1 is adopted as it is.

On the other hand, if it is determined in step C6 that the steering angle neutral position learned flag F _H has not been set, the steering angle δ calculated by the equation (2) is not reliable.
Without using the target drive torque T _OC calculated by the equation (8),
The TCL 76 outputs the maximum torque of the engine 11 at C9 as the target drive torque T _OC , whereby the ECU 15 reduces the duty ratio of the torque control solenoid valves 51 and 56 to the 0% side. A drive torque corresponding to the amount of depression of the accelerator pedal 31 is generated.

If it is determined in step C3 that the target drive torque T _OC is not equal to or smaller than the threshold value (T _d -2), the flow does not shift to the turning control, and the control proceeds from step C6 or C7 to C9.
The TCL 76 determines the target drive torque T _OC
Output the maximum torque of the engine 11 as
As a result of U15 reducing the duty ratio of the torque control solenoid valves 51 and 56 to the 0% side, the engine 11 generates a driving torque corresponding to the amount of depression of the accelerator pedal 31 by the driver.

Similarly, when the idle switch 68 is turned on in step C4, that is, when it is determined that the accelerator pedal 31 is not depressed by the driver, the TC
L76 outputs the maximum torque of the engine 11 as the target drive torque T _OC , whereby the ECU 15 reduces the duty ratio of the torque control solenoid valves 51 and 56 to the 0% side. The drive torque is generated in accordance with the amount of depression of the vehicle, and the process does not shift to the turning control.

If it is determined in step C2 that the turning control flag F _C has been set, the target driving torque T _OC calculated this time and the target driving torque T _{OC (n−n)} calculated last time are determined in C10. _It is determined whether or not the difference ΔT from ₁₎ is larger than a preset increase / decrease allowable amount T _K. The allowable increase / decrease amount T _K is a torque change amount that does not cause the occupant to feel the acceleration / deceleration shock of the vehicle 82. For example, when the target longitudinal acceleration G _XO of the vehicle 82 is to be suppressed to 0.1 g / sec,
(7) a _{T K = 0.1 · W b ·} r · Δt / ρ m · ρ d · ρ T utilized.

In step C10, the target drive torque T _OC calculated this time and the target drive torque T calculated last time are calculated.
_{If it} is determined that the difference ΔT from _{OC (n−1)} is not larger than the preset increase / decrease allowable amount T _{K, the} target drive torque T _OC and the previously calculated target drive torque T _{OC (n} are determined at C11. _-1)
Then, it is determined whether or not the difference ΔT is larger than the negative increase / decrease allowable amount T _K.

In the step C11, the target drive torque T _OC calculated this time and the target drive torque T _{OC (n-1)} calculated last time are calculated.
Absolute value of the difference between the difference [Delta] T is determined to be larger than the negative decrease tolerance T _K, the target driving torque calculated this time T _OC and the target driving torque T _OC previously calculated _(n-1) and | [Delta] T | Is smaller than the allowable increase / decrease amount T _K , the calculated target drive torque T _OC is used as it is in the step C8.

If it is determined in step C11 that the difference ΔT between the currently calculated target driving torque T _OC and the previously calculated target driving torque T _OC is not larger than the negative increase / decrease allowable amount T _K , the process proceeds to C12. The current target drive torque T _OC is corrected by the following equation, and this is adopted as the value calculated in the step C8. T _OC = T _{OC (n−1)} −T _K

That is, the previously calculated target drive torque T
_The amount of decrease in _{OC (n-1)} is regulated by the permissible increase / decrease amount T _K , so that the deceleration shock accompanying the reduction in the driving torque of the engine 11 is reduced.

[0187] On the other hand, it is determined that the difference ΔT between the target drive torque currently calculated at C10 in Step T _OC and the target driving torque T _OC previously calculated _(n-1) is increased or decreased tolerance T _K or higher Then, at C13, the current target drive torque T _OC is corrected by the following equation, and this is adopted as the calculated value at the step of C8. T _OC = T _{OC (n-1)} + T _K

[0188] That is, as with the case of increasing the driving torque of the aforementioned drive torque reduction, the difference ΔT between the target driving torque calculated this time T _OC and the target driving torque T _OC previously calculated _(n-1) When the increase / decrease allowable amount T _K is exceeded, the increase width with respect to the previously calculated target drive torque T _{OC (n−1)} is regulated by the increase / decrease allowable amount T _K , and the acceleration shock accompanying the increase in the drive torque of the engine 11 is reduced. It is.

When the target drive torque T _OC is set as described above, the TCL 76 determines in C14 whether the target drive torque T _OC is larger than the driver's required drive torque T _d .

Here, if the turning control in-progress flag F _C is set, the target drive torque T _OC is not larger than the driver's required drive torque T _d. Is determined.

If it is determined in step C15 that the idle switch 68 is not in the ON state, it is determined that the turning control is required, and the flow proceeds to step C6.

If it is determined in step C14 that the target drive torque T _OC is larger than the driver's required drive torque T _d , it means that the turning of the vehicle 82 has been completed. reset turning control flag F _C at. Similarly, if it is determined in step C15 that the idle switch 68 is on,
Since the accelerator pedal 31 is not depressed, the process proceeds to step C16 and the turning control flag F _C
Reset.

When the turning control flag F _C is reset at _C 16, the TCL 76 outputs the maximum torque of the engine 11 at C 9 as the target drive torque T _OC , whereby the ECU 15 allows the torque control solenoid valve 51, As a result of reducing the duty ratio of 56 to the 0% side, the engine 11 generates a driving torque corresponding to the amount of depression of the accelerator pedal 31 by the driver.

It is naturally possible to ignore the driver's required driving torque _Td in order to simplify the above-described turning control procedure. In this case, the target driving torque is calculated by the above equation (7). it may be employed possible reference driving torque T _B. Further, even when the driver's required driving torque _Td is taken into account as in the present embodiment, the weighting coefficient α is not fixed, but the value of the coefficient α gradually decreases with the passage of time after the start of control. Alternatively, the driving torque may be gradually decreased in accordance with the vehicle speed V, and the ratio of the driver's required driving torque _Td may be gradually increased. Similarly, the value of the coefficient α is kept constant for a while after the start of the control, and is gradually decreased after a predetermined time has elapsed, or the steering shaft turning amount δ
It is also possible to increase the value of the coefficient α with an increase in _H , and to cause the vehicle 82 to travel safely, especially in a circuit in which the radius of curvature gradually decreases.

In the above-described embodiment, the target drive torque for the high μ road is calculated. However, the target drive torque for the turning control corresponding to the high μ road and the low μ road is calculated. The final target driving torque may be selected from among the target driving torques. Further, in the above-described arithmetic processing method, in order to prevent the deceleration shock due to variations in the rapid driving torque of the engine 11, regulation of the target driving torque T _OC by decreasing tolerance T _K when calculating the target driving torque T _OC However, this restriction may be applied to the target longitudinal acceleration G _XO .

After calculating the target drive torque T _OC for turning control, the TCL 76 selects an optimal final target drive torque T _O from these two target drive torques T _OS and T _OC , and outputs this to the ECU 15. . In this case, the vehicle 82
In consideration of the traveling safety of the vehicle, the smaller the numerical value, the higher the target driving torque is output. However, since the target drive torque T _OS for slip control is generally always smaller than the target drive torque T _OC for turn control, the final target drive torque T _O must be selected in the order of slip control and turn control. Good.

As shown in FIG. 42 showing the flow of this process, after the target drive torque T _OS for slip control and the target drive torque T _OC for turning control are calculated in B11, B1
During slip control flag at 2 F _S it is determined whether it is set, if the slip control flag F _S is determined to have been set, the final target driving torque T _O
The target drive torque T _OS for slip control is selected at B13, and this is output to the ECU 15.

On the other hand, if it is determined in step B12 that the slip control flag F _S has not been set, it is determined in B14 whether or not the turning control flag F _C has been set. If it is determined that the control flag F _C has been set, the final target drive torque T _{O is determined.}
The target drive torque T _OC for turning control is selected at B15, and this is output to the ECU 15.

[0199] Further, if the turning control flag F _C is determined in step B14 is determined not to be set, T
The CL 76 outputs the maximum torque of the engine 11 to the ECU 15 at B16 as the final target drive torque T _O.

As described above, the final target drive torque T _O
On the other hand, at the time of sudden start where the output of the engine 11 cannot be reduced in time even if the throttle valve 20 is operated via the actuator 41 or when the road surface condition suddenly changes from a normal dry road to a frozen road, the TCL 76 set retarding proportion to the basic retard amount p _B of the ignition timing P is set Te, and outputs it to the ECU 15.

[0202] The basic retardation amount p _B is the maximum value of the retard angle so as not hindrance to operation of the engine 11 are set based on the intake air amount and the engine rotational speed N _E of the engine 11 but basically in accordance with the rate of change G _s of the slip amount s is increased, and selecting the retard rate such that a significant amount of retardation. In this embodiment, the basic retardation amount p _B is used as the retardation ratio.
A 0 level to 0, and I level to compress the basic retard amount p _B two-thirds, directly outputs the basic retard amount p _B
And II levels, four is set in a fully closed operation to III levels throttle valve 20 while it outputs the base retardation amount p _B. That is, by combining the fully closing operation of the throttle valve 20 at the III level and the above-described retarding operation, the driving torque of the engine 11 can be reduced very quickly, and the slip of the front wheels 64 and 65 can be converged.

FIG. 41 shows a procedure for reading out the retardation ratio.
And FIG. 42, TCL76 first resets the ignition timing control flag F _P at P1, determines whether the slip control flag F _S at P2 is set. In the step P2, the slip control flag F _{S is set.}
Is set, the ignition timing control flag _FP is set at P3, and it is determined at P4 whether the slip amount s is less than 0 km / h. In addition, a step in the slip control flag F _S of the P2 is determines that not set, the process proceeds to step of the P4.

If it is determined in step P4 that the slip amount s is less than 0 km / h, that is, it is determined that there is no problem in increasing the drive torque of the engine 11, the retard ratio is set to the 0 level in P5, and this is set. Output to ECU15. Conversely, if it is determined in step P4 that the slip amount s is equal to or greater than 0 km / h, the slip amount change rate G _S is determined in P6.
Is determined to be 2.5 g or less, and if it is determined in step P6 that the slip amount change rate G _S is 2.5 g or less, the retard angle ratio is set to the III level in P7. It is determined whether or not there is.

In the step P6, the slip amount change rate G _S exceeds 2.5 g, that is, the front wheels 64, 6
If the 5 is determined to be slipping, the final target driving torque T _O is equal to or less than 4Kgm at P8, the final target driving torque T _O is less than 4Kgm,
That is, when it is determined that the driving torque of the engine 11 needs to be rapidly suppressed, the retardation ratio is set to the III level in P9, and the process proceeds to the step P7. Conversely, if the final target driving torque T _O is equal to or greater than 4kgm at P8 step proceeds directly to P7 step.

[0205] In the step of P7, the retardation ratio becomes III
If it is determined that the level is the level, it is determined in P10 whether the slip amount change rate G _S exceeds 0 g. here,
When it is determined that the slip amount change rate G _S exceeds 0 g, that is, the slip amount s tends to increase, P1
Ignition timing control flag F _P at 1 determines whether it is set, judges that the slip rate of change G _S at P10 in step is less than 0 g, i.e. the slip amount s is in phenomenon tends In this case, it is determined in P12 whether the slip amount s exceeds 8 km / h.

If it is determined in step P12 that the slip amount s exceeds 8 km / h, the program proceeds to step P11.
Conversely, if it is determined that the slip amount s is 8 km / h or less, the retard ratio is set to III at P13.
The level is switched from the level II to the level II, and it is determined in P14 whether the slip amount change rate G _S is 0.5 g or less. Similarly, when it is determined in the step P7 that the retardation ratio is not at the III level, the process shifts to the step P14.

If it is determined in step P14 that the slip amount change rate G _S is 0.5 g or less, that is, the change in the slip amount s is not too sharp, the program proceeds to P15, where the retardation ratio is set to the II level. Is determined. Also, P14
If the slip rate of change G _S determined in step is determined not to be less 0.5g sets the retard rate at P16 in II level, the processing proceeds to step P15.

If it is determined in step P15 that the retardation ratio is at the II level, it is determined in step P16 whether or not the slip amount change rate G _S exceeds 0 g. If it is determined that the ratio is not at the II level,
At 17, it is determined whether or not the slip amount change rate G _S is 0.3 g or less. If it is determined in step P16 that the slip amount change rate G _S does not exceed 0 g, that is, the slip amount s is in a decreasing tendency, the slip amount s exceeds 8 km / h in P18. Is determined. If it is determined in the step P18 that the slip amount s is equal to or less than 8 km / h, the retard rate is switched from the II level to the I level in P19, and the process proceeds to the step P17. Further, when it is determined in the step P16 that the slip amount change rate G _S is 0 g or more, that is, the slip amount s tends to increase, and in the step P18, the slip amount s exceeds 8 km / h. That is, when it is determined that the slip amount s is large, the process shifts to the step P11.

If it is determined in the step P17 that the slip amount change rate G _S is 0.3 g or less, that is, the slip amount s is hardly increasing, the retard ratio is at the I level in P20. It is determined whether or not. Conversely, if it is determined in step P17 that the slip amount change rate G _S exceeds 0.3 g, that is, that the slip amount s tends to increase at all, the retard ratio is set to I in P21. Set to level.

If it is determined in step P20 that the retardation ratio is at the I level, it is determined in step P22 whether or not the slip amount change rate G _S exceeds 0 g. That is, when it is determined that the slip amount s tends to decrease, it is determined at P23 whether the slip amount s is less than 5 km / h. If it is determined in step P23 that the slip amount s is less than 5 km / h, that is, that the front wheels 64 and 65 are hardly slipping, the retard ratio is set to the 0 level in P24, and this is set in the ECU 15. Output. Further, when it is determined in the step P20 that the retard ratio is not at the I level, or in the step P22, the slip amount change rate G _S exceeds 0 g, that is, the slip amount s
Is determined to be increasing, or when it is determined in step P23 that the slip amount s is equal to or greater than 5 km / h, that is, when the slip amount s is relatively large, the process shifts to step P11.

[0211] On the other hand, if the ignition timing at step control flag F _P of the P11 is determined to be set, the final target driving torque T _O at P25 it is equal to or less than 10Kgm. Further, when it is determined in step by the ignition timing control flag F _P of P11 is not set, the process proceeds to retard the rate at P26 after setting to zero level P25 step.

If it is determined in P25 that the final target drive torque T _O is equal to or greater than 10 kgm, that is, if the engine 11 is generating a somewhat large drive force, the program proceeds to P27.
It is determined whether or not the retardation ratio is at the II level. If the retardation ratio is determined to be at the II level, the retardation ratio is reduced to the I level at P28, and this is output to the ECU 15. I do.

In the step P25, when it is determined that the final target drive torque T _O is less than 10 kgm,
If it is determined in step 7 that the retard ratio is not at the II level, it is determined in P29 whether the hydraulic automatic transmission 13 is shifting. If it is determined that the hydraulic automatic transmission 13 is shifting, the retard ratio is determined at P30.
It is determined whether or not the retardation ratio is at the III level. If the retardation ratio is determined to be at the III level in the step of P30, the retardation ratio is reduced to the II level at P31, and this is reduced to E level.
Output to CU15. Also, if it is determined in step P29 that the hydraulic automatic transmission 13 is not shifting, or if it is determined in step P30 that the retardation ratio is not at the III level, first in P32, The set retardation ratio is output to the ECU 15 as it is.

For example, when the retardation ratio at the III level is set in the step P9, the slip amount change rate G _S becomes zero.
g, and the slip amount s exceeds 8 km / h, that is, the rate of increase of the slip amount s is sharp, the final target drive torque T _O is less than 10 kgm, and the front wheel is only operated by retarding the ignition timing. When it is determined that it is difficult to sufficiently suppress the slip of 64, 65, the retardation ratio of the III level is selected, the opening of the throttle valve 20 is forcibly set to the fully closed state, and the occurrence of the slip is reduced. At the initial stage, we try to keep it efficient.

[0215] The ECU15 from the map (not shown) about the retardation amount p _B as a preset ignition timing P and basic based on the intake air amount of the engine speed N _E and the engine 11, these ignition timing P and basic The retardation amount p _B is read based on the detection signal from the crank angle sensor 62 and the detection signal from the air flow sensor 70, and is corrected based on the retardation ratio sent from the TCL 76 to obtain the target retardation amount p _O.
Is calculated. In this case, the upper limit value of the target retardation amount p _O is set in accordance with the upper limit temperature of the exhaust gas so as not to damage the exhaust gas purification catalyst (not shown). It is detected by the detection signal.

If the cooling water temperature of the engine 11 detected by the water temperature sensor 71 is lower than a preset value, retarding the ignition timing P may cause knocking and stall of the engine 11. Therefore, the retard operation of the ignition timing P described below is stopped.

As shown in FIGS. 45 and 46 showing the procedure for calculating the target retardation amount p _O in this retard control, first, EC
U15 determines whether the slip control flag F _S described above in Q1 is set, when the slip control flag F _S is determined to be set, retarding the rate at Q2 is a III level It is determined whether or not it has been set.

[0218] When the retard rate is determined in step Q2 is determined to be III level, using base retardation amount p _B read out from the map at Q3 as it target retard amount p _O , The ignition timing P is retarded by the target retardation amount p _O. Further, the duty ratio of the torque control solenoid valves 51 and 56 is set to 100% in Q4 so that the throttle valve 20 is fully closed regardless of the value of the final target drive torque T _O.
To forcibly realize the fully closed state of the throttle valve 20. Thus, even if the slip rate of change G _s is increasing rapidly, it is possible to stifle efficiently the occurrence of slip in its early stages.

If it is determined in step Q2 that the retardation ratio is not at the III level, the retardation ratio is determined in step Q5.
Determine whether or not it is set to the II level. And
If it is determined in step Q5 that the retardation ratio is at the II level, the basic retardation amount p _B obtained by reading the target retardation amount p _O from the map in step Q6, as in step Q3.
Is used as it is as the target retardation amount p _O , and the ignition timing P is retarded by the target retardation amount p _O. Further, in Q7, the ECU 1
5 sets the duty ratio of the torque control solenoid valves 51 and 56 in accordance with the value of the target drive torque T _OS by Q7, regardless of the amount of depression of the accelerator pedal 31 by the driver.
The drive torque of the engine 11 is reduced.

[0220] Here, the ECU15 is stored a map for determining the throttle opening theta _T and a driving torque of the engine speed N _E and the engine 11 as parameters, ECU
15 is a target throttle opening θ corresponding to the current engine speed _NE and the target drive torque T _OS using this map.
_{Read TO} .

Next, the ECU 15 obtains the deviation between the target throttle opening θ _TO and the actual throttle opening θ _T output from the throttle opening sensor 67, and calculates the duty ratio of the pair of torque control solenoid valves 51 and 56. Is set to a value commensurate with the above-mentioned deviation, a current flows through the solenoids of the plungers 52, 57 of the torque control solenoid valves 51, 56, and the actual throttle opening θ _T is changed by the operation of the actuator 41 to the target throttle opening θ _TO Control to go down to.

The target driving torque T _OS is the engine 11
Is output to the ECU 15, the ECU 1
5 is the duty ratio of the solenoid valves 51 and 56 for torque control being 0
%, And the engine 11 generates a drive torque corresponding to the amount of depression of the accelerator pedal 31 by the driver.

If it is determined in step Q5 that the retardation ratio is not at the II level, then in step Q8, the retardation ratio is set to the I level.
It is determined whether or not the level is set. If it is determined in step Q8 that the retard ratio is set to the I level, the target retard amount p _O is set as in the following equation, and the ignition timing P is delayed by the target retard amount p _O. Squaring and Q7
Go to step. p _O = p _B · 2/3

On the other hand, if it is determined in step Q8 that the retard ratio is not at the I level, it is determined in Q10 whether or not the target retard amount p _O is zero. If it is determined that there is no delay, the process proceeds to step Q7 to set the duty ratio of the torque control solenoid valves 51 and 56 in accordance with the value of the target drive torque T _OS without delaying the ignition timing P. The driving torque of the engine 11 is reduced irrespective of the amount by which the accelerator pedal 31 is depressed.

If it is determined in step Q10 that the target retardation amount p _O is not 0, the target retardation amount p _O is controlled by ramp control at step Q11 for each sampling period Δt of the main timer. Subtraction is performed once at a time until p _O = 0, and the shock caused by the fluctuation of the driving torque of the engine 11 is reduced. Then, the process proceeds to step Q7.

If it is determined in step Q1 that the slip control flag F _S has been reset, normal driving control is performed without reducing the driving torque of the engine 11, and p _O = 0 in Q12. By setting the duty ratio of the torque control solenoid valves 51 and 56 to 0% in Q13 without delaying the ignition timing P, the engine 11 drives the driving torque according to the amount of depression of the accelerator pedal 31 by the driver. Generate.

After calculating the target retardation amount p _O in the ignition timing control in this manner, the ECU 15 calculates the differential restraining torque of the restraining torque adjusting clutch 89 as the absolute value of the front wheel speed difference | V _FR -V _FL | Set based on

As shown in FIGS. 47 and 48 showing the calculation procedure for the differential constraint torque control, the ECU 15 determines the absolute value | V _FR of the front wheel speed difference based on the detection signals from the front wheel rotation sensors 66 and 97. −V _FL | is calculated by the peripheral speed difference calculator 151. At this time, if the vehicle 82 is turning, a peripheral speed difference ΔV _F is inevitably generated in the front wheels 64 and 65 due to the turning. the absolute value of the front wheel speed difference of the speed difference ΔV _F | V
_FR− V _FL |. Here, the vehicle 82
Assuming that the turning radius of C _r is C _r , ΔV _F = b · V / C _r , but C _r = ω · (1 + A · V ² ) / δ.

In this embodiment, however, the reference peripheral speed difference ΔV _BF of the front wheels 64 and 65 per unit steering angle (for example, 120 degrees) corresponding to the vehicle speed V is calculated by the reference peripheral speed difference calculator 153 by the ECU.
49 is read out from the map stored in FIG. 49 and multiplied by the steering angle (δ _H / 120) by the multiplication unit 154 to obtain the peripheral speed difference Δ between the front wheels 64 and 65 due to the turning.
And calculates the V _F. Then, the corrected front wheel speed difference ΔV _FF as shown in the following equation is calculated by the turning correction calculation unit 152, and stored in the ECU 15 by the reference differential constraint torque calculation unit 155 based on the corrected front wheel speed difference ΔV _FF . The reference differential constraint torque T _BF is calculated from a map as shown in FIG. ΔV _FF = | V _FR −V _FL | −ΔV _BF · δ _H / 120

In this case, the differential restraint torque of the restraint torque adjusting clutch 89 is changed between the high μ road and the low μ road, that is, the differential restraint torque is set to be relatively high on the high μ road, and on the low μ road. It is desirable to set the differential restraining torque to a relatively low value. Therefore, the reference differential restraining torque T _BF depends on the road surface μ.
Needs to be corrected, and the road surface μ estimating means 156 estimates the road surface μ.

By the way, as shown in FIG. 51 showing the steering state of the right front wheel 65, the cornering force _DF generated on the front wheel 65 during turning is represented by the following equation (9). D _F ∝δ _F · μ (9) where δ _F is the side slip angle of the front wheel 65 with respect to the traveling direction of the vehicle 82 (the longitudinal direction of the vehicle 82 corresponds to the vertical direction in the figure), and μ is the road surface The coefficient of friction.

Here, as shown in FIG. 52 showing the relationship between the sideslip angle δ _F and the cornering force _DF , even if the sideslip angle δ _F is a constant value, the cornering force _DF varies greatly depending on the road surface condition. There is generally a large value with an increase of more slip angle [delta] _F is larger road mu. Also, the cornering force _DF and the power steering pressure P
_As is clear from FIG. 50, _S is almost proportional from the mechanical relationship. Therefore, if C ₁ is a proportional constant, the equation (9) is modified and expressed as the following equation (10). be able to. P _S = C ₁ · δ _F · μ (10)

[0233] On the other hand, since the side slip angle [delta] _F can be expressed by the following equation (11), (10) and the (11) the ratio between the power steering pressure P _S and the steering shaft turning angle [delta] _H from the equation, i.e. P _S / _{δ H} is the following formula
(12). δ _F = C ₂ · V ² · δ _H / (μ + C ₃ · V ² ) (11) P _S / δ _H = μ · C ₁ · C ₂ · V ² / (μ + C ₃ · V ² ) (12) where C ₂ and C ₃ are constants.

Therefore, based on the power steering pressure P _{S, the} steering shaft turning angle δ _H, and the vehicle speed V output to the road surface μ estimating means 156, the road surface μ can be calculated by the above equation (12).

As shown in FIG. 53 showing the calculation procedure by the road surface μ estimating means 156, the power steering pressure P _S calculated based on the detection signals from the pressure sensors 98 and 99 is detected by the pressure sensors 98 and 99. The subtraction unit 157 calculates the power steering pressure P _S , which is the absolute value of the pressure difference between the pressures P _LS and P _RS in the pressure chamber of the power actuator 91, and then passes through the phase compensation filter 158 to calculate the road μ calculation unit 159.
Is output to The steering shaft turning angle δ _H calculated based on the detection signal from the steering angle sensor 84 and the vehicle speed V calculated based on the detection signals from the rear wheel rotation sensors 80 and 81 are transmitted through the communication cable 87 from the TCL 76. The output is output to the road surface μ calculating unit 159 via this.

The phase compensating filter 158 includes a subtractor 1
For removing noise in the signal corresponding to the power steering pressure P _S output from the motor 57 and compensating for the phase advance of the power steering pressure P _S with respect to the steering shaft turning angle δ _H during the steering transition period of the steering wheel 85. It is. That is, as shown in FIG. 54 showing the relation between the change in the change and the power steering pressure P _S of the steering shaft turning angle [delta] _H during steering, a phase compensation filter 1
When the steering wheel 94 is not used, as shown by a solid line in the figure due to the characteristics of the steering valve 94, the power steering pressure P changes with respect to a change in the steering shaft turning angle δ _H caused by the turning of the steering wheel 85.
_S rises significantly earlier, also has a power steering pressure P _S falls tendency early to changes in the steering shaft turning angle [delta] _H due to the switch-back of the steering wheel 85. However, by using the phase compensation filter 158, as shown by the broken line in the figure, the change in the power steering pressure P _S is caused to follow the change in the steering shaft turning angle δ _H without causing a phase shift, it is possible to remove the phase advance of the power steering pressure P _S in the steering transition of the steering wheel 85.

The road surface μ calculated by the road surface μ calculation unit 159
Are output to the road surface correction coefficient calculating unit 162 shown in FIGS. 47 and 48 via the μ variation limiting unit 160 and the stabilizing filter 161 for stabilizing the value of the road surface μ. here,
When the rate of change of the road surface μ is within a predetermined range, the μ fluctuation limiting unit 160 outputs the road surface μ calculated by the road surface μ calculation unit 159 to the stabilizing filter 161, so that the stable μ is output from the stabilization filter 161 to the road surface correction coefficient calculation unit 162.

FIG. 55 showing the flow of the road surface μ estimation operation.
56, the rear wheel speed sensor 8 is first set at J1.
0, 81, the steering angle sensor 84, and the pressure sensors 98, 9
The vehicle speed V, the steering shaft turning angle δ _H and the power actuator 9 calculated based on the detection signal from
The pressures P _LS and P _{RS in the} first pressure chamber are read, respectively.
Next, at J2, the differential pressure between the pressures P _LS and P _RS in the pressure chamber of the power actuator 91, that is, the power steering pressure P _S is calculated. The power steering pressure P _{S is} subjected to the above-described processing by the phase compensation filter 158 at J3, and whether or not the steering shaft turning angle δ _H is not 0 at J4 or the steering shaft calculated this time is determined. or equal or not the turning angle [delta] _{H (n)} is a steering shaft turning angle previously calculated δ _{H (n-1)} is determined.

In step J4, the steering shaft turning angle δ _H
Is 0 or the steering shaft turning angle δ _{H (n)} calculated this time
Is not the same as the previously calculated steering shaft turning angle δ _{H (n-1)} , the process returns to the step of J1.
In step 4, the steering shaft turning angle δ _H is not 0, or the steering shaft turning angle δ _{H (n)} calculated this time is the same as the steering shaft turning angle δ _{H (n-1)} calculated last time. When it is determined that the absolute value of the steering shaft turning angle δ _H is equal to or larger than a predetermined value δ _H1 (for example, 10 degrees), it is determined in J5.

In the step of J5, the steering shaft turning angle δ _H
If the absolute value of is determined to be less than the predetermined value δ _H1 ,
Returning to J1 step, when the absolute value of the steering shaft turning angle [delta] _H is determined in step J5 is determined to be the predetermined value [delta] _H1 above the steering shaft turning angle and the power steering pressure P _S in J6 [delta]
The ratio to _H , that is, P _S / δ _H is calculated by the above (12).

Thereafter, at J7, the sign of the power steering pressure P _S is equal to the sign of the steering shaft turning angle δ _H , that is, P _S
/ Sign of [delta] _H is positive or not is determined. If it is determined in step J7 that the sign of P _S / δ _H is negative, the power steering pressure P _S and the steering shaft turning angle δ _H are determined due to the phase compensation filter processing in step J3. It is determined that the phase inversion has occurred during the period, and the process returns to the step J1. If it is determined in step J7 that the sign of P _S / δ _H is positive, the multiplication coefficient K _m for calculating the road surface μ is read from the map shown in FIG. 57 at J8. This map is obtained by defining a multiplication factor K _m corresponding to the vehicle speed V, the stored in a memory not shown in advance in the ECU 15.

Here, when the above equation (12) is modified, μ = P _S · {1 + C ₃ · V ² / C ₁ · C ₂ · V ² } / δ
_H , but the multiplication coefficient K _m is equivalent to K _m = 1 + C ₃ · V ² / C ₁ · C ₂ · V ² .

Therefore, the road surface μ can be expressed by the following equation. _{μ = P S · K m /} δ H

[0244] Next, the ratio P _S / [delta] _H of the calculated and the power steering pressure P _S and the steering shaft turning angle [delta] _H in step multiplication factors K _m and J6 read at J8 step at J9 To calculate the road surface μ.

Thereafter, at J10, the change rate dμ /
It is determined whether the absolute value of dt is within a predetermined value Δμ (for example, 0.2 μ per second). This J10
If it is determined in the step that the absolute value of the change rate dμ / dt of the road surface μ exceeds the predetermined value Δμ, the process returns to the step of J1, but the change rate of the road surface μ is determined in the step of J10. If it is determined that the absolute value of dμ / dt is within the predetermined value Δμ, the road surface μ calculated in the step of J9 is determined.
After stabilizing filter processing is performed in J11 in order to stabilize the value of, the road surface μ is output in J12.

[0246] Note that by the absolute value of the steering shaft turning angle [delta] _H in step J5 In this embodiment it is determined whether a predetermined value [delta] _H1 above, the steering shaft turning angle [delta] _H is a predetermined value [delta] _H1
In the above case, that is, whether the power steering pressure P _S rises substantially by steering the front wheels 64 and 65, and whether the sign of the power steering pressure P _{S and} the sign of the steering shaft turning angle δ _H are the same in step J7. By determining whether or not the road surface μ is calculated only when the directions of the power steering pressure P _S and the steering shaft turning angle δ _H are the same, the road surface μ can be accurately estimated. That is, the characteristics of the steering valve 94 and the front wheels 64, 6
In this way, the road surface μ can be accurately calculated by removing the influence of inertia and the like associated with the steering of No. 5. On the other hand, if any one of the determination processes in the steps J4, J5, and J7 is negative, the processes after the step J8 are not performed, and in this case, the road surface μ calculated last time remains unchanged. Will be output.

Further, in this embodiment, even if the processing after the step of J8 is executed to calculate the road surface μ, if the rate of change dμ / dt of the road surface μ is larger than the predetermined value Δμ,
The value of the road surface μ is not updated by the determination operation in step J10, and even if the determination in step S10 is positive, the road surface μ is output through the stabilization filter processing. Output road surface μ
Does not change abruptly, and its value becomes stable.

[0248] Incidentally, when the present embodiment detects the power steering pressure P _S, detects the pressure in the pressure chamber of the left and right of the power actuator 91 by a pair of pressure sensors 98 and 99, the differential pressure power steering pressure P of the pressure chamber was calculated as the _S, it is possible to detect on the basis of the power steering pressure P _S in the output from one pressure sensor incorporated in the discharge side of the hydraulic pump 95. Further, in the present embodiment, the information of the road surface μ is used for the differential restraint torque control. However, it is naturally possible to use the information of the road surface μ for the turning control described above, and conversely. Alternatively, the road surface μ may be estimated by the method described above in the description of the turning control.

The road surface μ is estimated in this way, and the ECU 1
The road surface correction coefficient K _R corresponding to the road surface μ is calculated from the map as shown in FIG.
The multiplication unit 163 multiplies the road surface correction coefficient K _R by the reference differential constraint torque T _BS to calculate a corrected differential constraint torque T _BF .

By the way, the method of setting the differential restraining torque based on the front wheel speed difference | V _FL -V _FR |
Since the differential restraining torque is increased only after a slip has occurred in at least one of the clutches 5 and the differential restraining torque is reduced again when the slip is eliminated, control hunting may occur particularly when the vehicle 82 starts moving. Therefore, the vehicle 82
Is determined from the accelerator opening θ _A and the vehicle speed V, and it is desirable that the differential restricting torque of the restricting torque adjusting clutch 89 when the vehicle 82 starts moving is maintained slightly higher.

Therefore, based on the output signal from the accelerator opening sensor 77, the additional restraint torque calculating section 164 calculates the ECU
The reference addition constraint torque _TSS is read from the map as shown in FIG.
At step 5, a vehicle speed correction coefficient K _S corresponding to the vehicle speed V is read from a map as shown in FIG.
This is multiplied by the reference addition restraint torque T _SS by the multiplication unit 166, and further based on the detection signal from the steering angle sensor 84, the turning angle correction coefficient calculating unit 167 calculates the turning angle correction coefficient K from the map shown in FIG. _C is read out and multiplied by 16
At step 8, the value calculated by the multiplication unit 166 is multiplied to obtain an additional differential constraint torque T _SP .

As described above, in the present embodiment, the starting state of the vehicle 82 is estimated from the accelerator opening θ _A and the vehicle speed V, and
Although the differential restraining torque of the restraining torque adjusting clutch 89 at the time of starting 2 is slightly increased, it is naturally possible to estimate the starting state of the vehicle 82 by another known method.

The differential constraint torque calculating section 169 calculates the corrected differential constraint torque T _BF and the addition differential constraint torque T
_The final differential restraining torque _TF is calculated by adding _SP to the following equation. T _F = T _BF + T _SP

Thereafter, in addition to the differential constraint torque _TF calculated by the differential constraint torque calculation section 169 in consideration of control safety and the like, the maximum differential constraint torque T _SL according to the road surface μ is set.
Based on the output from the road surface correction coefficient calculation unit 162,
Calculated by the maximum differential restraining torque calculating section 170, the maximum value of the differential restraint torque T _F which is calculated by the differential restraint torque calculation unit 169 by the clip processing unit 171 to the maximum differential restraining torque T _SL regulate. However, the maximum differential restraining torque T _SL constraining torque adjusting clutch 89 is set to such a value that should not the direct connection state in the present embodiment.

Thus, when the spare tire is punctured with the spare tire mounted, an excessive differential constraint torque _TF based on an abnormal front wheel speed difference | V _FL -V _FR | Although calculated at 169, the clip processing unit 171 suppresses the differential torque to such a level that the clutch 89 for restricting torque adjustment is not directly connected.

As shown in FIG. 62 and FIG. 63 showing the flow of the process for the differential constraint torque control, the absolute value | V _FR -V _FL | of the front wheel speed difference is calculated at D1. Then, D2
Subtracts the front wheel speed difference ΔV _F associated with the turning of the vehicle 82 from the absolute value | V _FR −V _FL | of the front wheel speed difference, and corrects it at D3 based on the corrected front wheel speed difference ΔV _FF calculated thereby. Calculate the differential constraint torque T _BF . Then, in D4, it is determined whether or not the corrected differential restraint torque T _{BF (n)} calculated this time is larger than the corrected differential restraint torque T _{BF (n-1)} calculated previously.

If it is determined in step D4 that the corrected differential constraint torque T _{BF (n)} calculated this time is _{equal to} or greater than the differential constraint torque T _{BF (n-1)} calculated last time, the process proceeds to D5. The corrected differential restraint torque T _BF is set to the corrected differential restraint torque T _{BF (n)} calculated this time, and the responsiveness of the control is enhanced to ensure the traveling safety of the vehicle 82. Then, the addition differential constraint torque T _SP is calculated in D6. If it is determined in step D4 that the corrected differential constraint torque T _{BF (n)} calculated this time is smaller than the previously calculated corrected differential constraint torque T _{BF (n-1)} , because there is a possibility by setting the torque T _BF directly to the current calculated differential restraining torque T _{BF (n),} in which a decrease in driving stability due to a sharp drop in modified differential restraining torque T _BF expected, D7 The corrected differential restraint torque T _BF calculated the corrected differential restraint torque T
_The value is then reset to a value obtained by subtracting the preset constant value ΔT _BF from _{BF (n−1),} and the process proceeds to step D6 while ensuring the running stability of the vehicle 82.

After calculating the addition differential constraint torque T _SP in step D6, the corrected differential constraint torque T _BF and the addition differential constraint torque T _SP are added in D8 to obtain the differential constraint torque T _SP. calculates the _F, then calculates a maximum differential restraint torque T _SL in accordance with the road surface μ at D9. Then, the differential restraint torque T _F at D10 determines whether less than this maximum differential restraining torque T _SL.

[0259] If the differential constraint torque T _F is determined in step D10 has a value greater than the maximum differential restraining torque T _SL is the maximum differential restraining torque differential restraint torque T _F at D11 T _SL Fixed to determine whether the slip control flag F _S is set at D12. D1
If it is determined at step 0 that the differential constraint torque _TF is equal to or less than the maximum differential constraint torque _TSL , there is no problem with the set differential constraint torque _TF. The process proceeds to step D12 without correcting the constraint torque T _F.

If it is determined in step D12 that the slip control flag F _S has been set, the process proceeds to step D12.
At 13, it is determined whether or not a skid control device (not shown) (not shown) that is mounted on the vehicle 82 and maintains the slip ratio between the tire and the road surface during braking at an optimum value is functioning. I do. Further, when it is determined that the slip control flag F _S is not set at D12 step, since the stop state differential restraining torque control in the present embodiment, the differential restraint torque at D14 T _F To 0
And the process proceeds to step D13.

If it is determined in step D13 that the ABS is not operating, the energization amount corresponding to the finally set differential constraint torque _TF is read from the map shown in FIG. The ECU 15 calculates the differential restraining torque T
An electric current corresponding to _F is supplied to the restraint torque adjusting clutch 89. If it is determined in step D13 that the ABS is operating, the front and rear wheels 6 are determined by the ABS.
4,65,78,79 All rotation control is performed,
Since it is necessary to prevent the control interference with the ABS, the differential restraining torque _TF is reset to 0 at D16, and the process proceeds to step D15 to maintain the differential device 90 in a fully functioning state. .

In the case of the vehicle 82 not equipped with the ABS, the process shifts from the steps D12 and D14 to the step D15. In this embodiment, the front-wheel drive type vehicle 82 has been described. However, the present invention can be applied to a rear-wheel drive type vehicle.

[0263]

According to the drive wheel differential limiting device of the present invention, the clutch for adjusting the restraining torque capable of arbitrarily adjusting the differential restraining torque for the left and right wheels and the running state of the vehicle are detected.
Traveling state detecting means and the traveling state detecting means.
A differential restraint torque calculating unit that calculates a differential restraint torque of the restraint torque adjustment clutch based on the output traveling state ; a road surface μ estimating unit that estimates a friction coefficient of a road surface; Based on the friction coefficient of the road surface
And the road surface μ-correction unit for correcting the differential restraint torque calculated by said differential constraint torque calculation unit so as to increase as can road surface friction coefficient is small, out of this road surface μ-correction unit
An electronic control unit that controls a differential restraining torque of the restraining torque adjusting clutch so as to obtain a differential restraining torque to be applied, based on an absolute value of a pair of left and right driving wheel speed differences,
Since the differential restraining torque of the restraining torque adjusting clutch for these drive wheels is arbitrarily changed according to the friction coefficient of the road surface, an appropriate difference is always achieved without impairing the turning performance of the vehicle on any road surface. The dynamic restraining torque can be applied to the restraining torque adjusting clutch.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of an embodiment in which a drive wheel differential limiting device according to the present invention is applied to a front wheel drive type vehicle equipped with an engine driving force control device.

FIG. 2 is a schematic configuration diagram of the present embodiment.

FIG. 3 is a graph showing a relationship between an amount of current supplied to a clutch for adjusting a restraint torque and a differential restraint torque.

FIG. 4 is a schematic configuration diagram of a power steering device according to the present embodiment.

FIG. 5 is a sectional view illustrating a drive mechanism of a throttle valve according to the embodiment.

FIG. 6 is a flowchart illustrating an overall flow of control according to the present embodiment.

FIG. 7 is a flowchart illustrating a flow of neutral position learning correction of the steering shaft.

FIG. 8 is a flowchart illustrating a flow of neutral position learning correction of the steering shaft.

FIG. 9 is a flowchart showing a flow of neutral position learning correction of the steering shaft.

FIG. 10 is a map showing a relationship between a vehicle speed and a variable threshold.

FIG. 11 is a graph illustrating an example of a correction amount when a neutral position of the steering shaft is learned and corrected.

FIG. 12 is a block diagram illustrating a procedure for calculating a target drive torque for slip control.

FIG. 13 is a block diagram illustrating a procedure for calculating a target drive torque for slip control.

FIG. 14 is a map showing a relationship between a vehicle speed and a correction coefficient.

FIG. 15 is a map showing the relationship between vehicle speed and running resistance.

FIG. 16 is a map showing a relationship between a steering shaft turning amount and a correction torque.

FIG. 17 is a map that regulates the lower limit value of the target drive torque immediately after the start of the slip control.

FIG. 18 is a graph showing a relationship between a coefficient of friction between a tire and a road surface and a slip ratio of the tire.

FIG. 19 is a map showing a relationship between a target lateral acceleration and a slip correction amount accompanying acceleration.

FIG. 20 is a map showing a relationship between a lateral acceleration and a slip correction amount accompanying a turn.

FIG. 21 is a circuit diagram for detecting an abnormality of a steering angle sensor.

FIG. 22 is a flowchart illustrating a flow of an abnormality detection process of the steering angle sensor.

FIG. 23 is a map showing a relationship between a vehicle speed and a correction coefficient.

FIG. 24 is a flowchart illustrating a flow of a procedure for selecting a lateral acceleration.

FIG. 25 is a map showing a relationship between a slip amount and a proportional coefficient.

FIG. 26 is a map showing a relationship between a vehicle speed and a lower limit value of an integral correction torque.

FIG. 27 is a graph showing an increase / decrease region of the integral correction torque.

FIG. 28 is a map showing a relationship between each shift speed of the hydraulic automatic transmission and a correction coefficient corresponding to each correction torque.

FIG. 29 is a map showing a relationship among an engine speed, a required drive torque, and an accelerator opening.

FIG. 30 is a flowchart illustrating the flow of slip control.

FIG. 31 is a block diagram illustrating a procedure for calculating a target drive torque for turning control.

FIG. 32 is a block diagram illustrating a procedure for calculating a target drive torque for turning control.

FIG. 33 is a map showing a relationship between a vehicle speed and a correction coefficient.

FIG. 34 is a graph showing a relationship between a lateral acceleration and a steering angle ratio for explaining a stability factor.

FIG. 35 is a map showing a relationship among a target lateral acceleration, a target longitudinal acceleration, and a vehicle speed.

FIG. 36 is a map showing a relationship between lateral acceleration and road load torque.

FIG. 37 is a graph showing an example of a procedure of learning correction of the fully closed position of the accelerator opening sensor.

FIG. 38 is a flowchart illustrating another example of the flow of learning correction of the fully closed position of the accelerator opening sensor.

FIG. 39 is a flowchart illustrating another example of the flow of learning correction of the fully closed position of the accelerator opening sensor.

FIG. 40 is a flowchart illustrating a flow of a turning control.

FIG. 41 is a flowchart illustrating a flow of a turning control.

FIG. 42 is a flowchart illustrating a flow of an operation of selecting a final target torque.

FIG. 43 is a flowchart illustrating a flow of a selection operation of a retardation ratio.

FIG. 44 is a flowchart illustrating a flow of an operation of selecting a retardation ratio.

FIG. 45 is a flowchart illustrating a procedure of engine output control.

FIG. 46 is a flowchart showing a procedure of engine output control.

FIG. 47 is a block diagram illustrating a calculation procedure of differential constraint torque control.

FIG. 48 is a block diagram illustrating a calculation procedure of differential constraint torque control.

FIG. 49 is a map showing a relationship between a vehicle speed and a reference peripheral speed difference.

FIG. 50 is a map showing a relationship between a corrected front wheel speed difference and a reference differential constraint torque.

FIG. 51 is a conceptual diagram showing the steering state of the right front wheel.

FIG. 52 is a graph showing the relationship between the sideslip angle and the cornering force.

FIG. 53 is a block diagram illustrating a calculation procedure by a road surface μ estimating unit.

FIG. 54 is a graph showing a relationship between a steering shaft turning angle and a power steering pressure.

FIG. 55 is a flowchart showing a road surface μ estimation procedure.

FIG. 56 is a flowchart showing a road surface μ estimation procedure.

FIG. 57 is a map showing a relationship between a vehicle speed and a multiplication coefficient.

FIG. 58 is a map showing a relationship between a road surface μ and a road surface correction coefficient.

FIG. 59 is a map showing a relationship between an accelerator opening and an additional restraint torque.

FIG. 60 is a map showing a relationship between a vehicle speed and a vehicle speed correction coefficient.

FIG. 61 is a map showing a relationship between a steering shaft turning angle and a turning correction coefficient.

FIG. 62 is a flowchart illustrating a procedure of differential restraint torque control.

FIG. 63 is a flowchart illustrating a procedure of differential restraint torque control.

[Explanation of symbols]

11 is an engine, 12 and 63 are output shafts, 13 is a hydraulic automatic transmission, 14 is an input shaft, 15 is an ECU, 16 is a hydraulic control device, 17 is a combustion chamber, 18 is an intake pipe, 19 is an intake passage,
0 is a throttle valve, 21 is a throttle body, 22 is a throttle shaft, 23 is an accelerator lever, 24 is a throttle lever, 25 is a cylinder, 26 is a bush, 27 is a spacer,
28 is a washer, 29 is a nut, 30 is a cable receiver, 31
Is the accelerator pedal, 32 is the cable, 33 is the color, 3
4 is a claw portion, 35 is a stopper, 36 is a torsion coil spring,
37 and 38 are spring receivers, 39 is a stopper pin, 40 is a torsion coil spring, 41 is an actuator, 42 is a diaphragm, 43 is a control rod, 44 is a pressure chamber, 45 is a compression coil spring, 46 is a surge tank, and 47 is a connection. Piping, 48 is a vacuum tank, 49 is a check valve, 50 and 55 are piping, 51 and 56 are torque control solenoid valves, 52 is a plunger, 53 is a valve seat, 54 is a spring, 57 is a plunger, 58
Is a spring, 59 is a fuel injection nozzle, 60 is a solenoid valve, 61 is a spark plug, 62 is a crank angle sensor, 64 and 65 are front wheels, 66 and 97 are front wheel rotation sensors, 67 is a throttle opening sensor, and 68 is an idle switch. , 69 are air cleaners, 70 is an air flow sensor, 71 is a water temperature sensor, 72
Is an exhaust pipe, 73 is an exhaust passage, 74 is an exhaust gas temperature sensor, 75
Is an ignition key switch, 76 is a TCL, 77 is an accelerator opening sensor, 78 and 79 are rear wheels, 80 and 81 are rear wheel rotation sensors, 82 is a vehicle, 83 is a steering shaft, 84 is a steering angle sensor, and 85 is steering. Steering wheel, 86 is a steering axis reference position sensor, 87 is a communication cable, 88 is a comparator,
89 is a clutch for adjusting the restraining torque, 90 is a differential gear, 9
1 is a power actuator, 92 is a power steering device, 93 is a tie rod, 94 is a steering valve, 95 is a hydraulic pump, 96 is a reservoir tank, and 98 and 99 are pressure sensors. Also, 101 and 102 are selection units, 103 is a changeover switch, 104, 105, 117, 126 and 12
7,129,132,135,146,147,15
4,163,166,168 are multiplication units, 106,13
1,138 is a differential operation unit, 107,110,125,1
33 and 136 are clip parts, 108 and 123 are filter parts, 109 is a torque conversion part, 111 is a running resistance calculation part,
112, 114, 119, 130 and 134 are adders, 1
13 is a cornering drag correction amount calculation unit, 115 is a variable clip unit, 116, 121, 124, 157 are subtraction units, 118 is an acceleration correction unit, 120 is a turning correction unit, and 12
2 is a lateral acceleration calculator, 128 is an integral calculator, 137,1
50 is a start / end determining unit, 140 is a vehicle speed calculating unit, 141
Is a target lateral acceleration calculator, 142 is a correction coefficient multiplier, 14
3 is a changeover switch, 144 is a target longitudinal acceleration calculation unit, 145 is a reference drive torque calculation unit, 149 is a change amount clipping unit, 151 is a peripheral speed difference calculation unit, 152 is a turning correction calculation unit, and 153 is a reference circumferential speed difference calculation. , 155 is a reference constraint torque calculating unit, 156 is a road surface μ estimating unit, 158 is a phase compensation filter, 159 is a road surface μ calculating unit, 160 is a μ fluctuation limiting unit, 161 is a stabilizing filter, and 162 is a road surface correction coefficient calculating unit. 164, an additional restraint torque calculator, 165, a vehicle speed correction coefficient calculator, 167, a turning correction coefficient calculator, 1
Reference numeral 69 denotes a differential constraint torque calculation unit, 170 denotes a maximum differential constraint torque calculation unit, and 171 denotes a clip processing unit. Furthermore, A
Is the stability factor, b is the tread of the rear wheel, C ₁ ,
C ₂ and C ₃ are constants, _Cr is the turning radius of the vehicle, D _F is the cornering force, F _C is the turning control flag, F _H and F
_HN is the steering angle neutral position learned flag, F _P is the ignition timing control flag, F _S is the slip control flag, F _W is abnormality flag, G _F is the actual front wheel acceleration, G _KC, G _KF front wheel acceleration The correction amount, G _s is the slip rate change rate, G _X is the longitudinal acceleration, G _XF is the corrected longitudinal acceleration, G _XO is the target longitudinal acceleration, and G
_Y is the lateral acceleration, G _YF is corrected lateral acceleration, G _YO is the target lateral acceleration, g is the gravitational acceleration, K _C is turning angle correction factor, K _D is a differential coefficient, K _m is the multiplication factor, K _P is a proportionality factor, K _R is the road correction factor, K _S is the vehicle speed correction coefficient, coefficient of K _V weighting, K _Y is the correction factor, N _E is engine speed, P is the ignition timing, P _LS, P _RS is the hydraulic chamber pressure, P _S is the power steering pressure, p
_B is a basic retard amount, p _o is the target retard amount, r is wheel effective radius, S _O is the target slip ratio, s is slip, T _B is the reference driving torque, T _BF is corrected differential restraint torque, T _C is cornering drag correction torque, T _D is a differential correction torque,
T _d is the required driving torque, T _F is the differential restraint torque, T _I is the integral correction torque, T _IL is integral correction torque limit value, T _K is increased or decreased tolerance, T _L the load load torque, T _O is the final goal Drive torque, T _OC is the target drive torque for turning control, T _OS
Target drive torque slip control, T _P is proportional correction torque, T _PI proportional integral correction torque, T _PID final correction torque, T _R is running resistance, T _SL is the maximum differential restraint torque, T _SP
Is the differential restraining torque for addition, T _SS is the reference additional restraining torque,
ΔT is the difference between the current and previous target drive torques, ΔT _BF is a constant value, ΔT _I is a small integral correction torque, ΔT _i is an integration constant, Δt is a sampling period, V is a vehicle speed, V _A , V _B ,
V _X is a threshold, V _F is the actual front wheel speed, V _FL left front wheel speed, V _FO is the reference torque calculation target front wheel speed, V _FR right front wheel speed, V _FS correction torque calculation target front wheel speed, V _H Is the larger rear wheel speed, V _K and V _KC are the slip correction amounts, V _KF is the corrected slip correction amount, _VL is the smaller rear wheel speed, V _RL is the left rear wheel speed, and V
_RR is the right rear wheel speed, V _S is the vehicle speed for slip control, ΔV _BF is the reference peripheral speed difference, ΔV _F is the front wheel speed difference due to turning, ΔV _FF is the corrected front wheel speed difference, W _b is the vehicle weight, α is Weighting factor,
front wheel steering angle [delta], [delta] _F is the side slip angle, [delta] _H is the steering shaft turning angle, δ _H1, Δμ predetermined value, [delta] _M is the neutral position, [delta] _m is a steering shaft pivoted position, [delta] _N is a steering shaft reference position , Δδ is the correction limit, μ is the friction coefficient, θ _A is the accelerator opening, θ _{A (0)} is the initial value of the accelerator opening, θ _AC is the fully closed value of the accelerator opening, θ _AL
Is the minimum accelerator opening, θ _T is the throttle opening, θ _TO
Is the target throttle opening, ρ _d is the differential gear reduction ratio, ρ _H is the steering gear transmission ratio, ρ _KI is the integral correction coefficient, ρ _KP is the proportional correction coefficient, ρ _m is the transmission ratio of the hydraulic automatic transmission, ρ _T is the torque converter ratio, and ω is the wheelbase.

Claims (1)

(57) [Claims] 1. A restraining torque adjusting clutch capable of arbitrarily adjusting a differential restraining torque for right and left wheels, and a running state of a vehicle.
Running state detecting means for detecting a running state;
A differential restraint torque calculating unit that calculates a differential restraint torque of the restraint torque adjusting clutch based on a traveling state detected by a step; a road surface μ estimating unit that estimates a friction coefficient of a road surface; so that the larger based-out road surface friction coefficient is small coefficient of friction is estimated road surface by
Said differential constraint and the road surface μ-correction unit for correcting the differential restraint torque calculated by the torque calculation unit, the restraining torque adjusting clutch to obtain the differential constraint torque output from the road surface μ-correction unit to And an electronic control unit for controlling the differential restraint torque of the drive wheel.