JPH07174037A - Vehicle turning control device - Google Patents

Abstract

(57) [Summary] [Purpose] While turning the vehicle, the engine output is reduced to ensure safety, and at the same time, at low speed or in low speed, acceleration is ensured to provide a driving feeling. It is an object of the present invention to provide a turning control device for a vehicle that secures [Configuration] The target drive torque is set to be lower as the lateral acceleration increases, and set to be higher as the vehicle speed decreases,
Moreover, since the speed is set to a high value at the low speed shift stage as compared to the case at other shift speeds, for example, when the vehicle speed is low and the shift speed is the low shift stage, such as when commonly called a T-shaped road start. It is possible to obtain sufficient acceleration when turning, and to safely turn at other gears.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turning control device for a vehicle, in which the driving torque of an engine is rapidly reduced in accordance with the magnitude of lateral acceleration generated when the vehicle turns to allow the vehicle to travel safely. .

[0002]

2. Description of the Related Art Centrifugal force corresponding to lateral acceleration in a direction perpendicular to the traveling direction is generated in a vehicle running on a turning circuit. There is a risk that the vehicle body will skid beyond the limit of the grip force. In such a case, in order to properly lower the output of the engine and safely drive the vehicle with a turning radius corresponding to the turning circuit, in the case where the exit of the turning circuit cannot be confirmed, or the radius of curvature of the turning circuit is In the case where the size becomes gradually smaller, extremely advanced driving skill is required. In a general vehicle having a so-called under-steering tendency, it is necessary to gradually increase the steering amount as the lateral acceleration applied to the vehicle increases. However, when the lateral acceleration exceeds a certain value peculiar to each vehicle, steering It has the characteristic that the amount of traffic suddenly increases and it becomes difficult or impossible to drive safely. It is well known that this tendency becomes remarkable especially in a front engine front-wheel drive type vehicle with a strong tendency to understeer.

Therefore, the lateral acceleration of the vehicle is detected and the engine is forcibly forced before the turning limit at which the vehicle becomes difficult or unable to turn, regardless of the amount of depression of the accelerator pedal by the driver. An output control device that reduces output can be considered, and the driver uses this output control device as needed and normal running that controls the output of the engine according to the amount of depression of the accelerator pedal. It has been announced that you can choose.

[0004]

In consideration of the running safety of the vehicle, the lateral acceleration of the vehicle is detected and is related to the amount of depression of the accelerator pedal by the driver before the vehicle becomes difficult or unable to turn. It is desirable that the vehicle be equipped with an output control device that forcibly reduces the output of the engine.

Conventionally, however, this output control device has detected that the vehicle is difficult to turn or unable to turn only due to the lateral acceleration of the vehicle. Therefore, even when the vehicle turns at a relatively small radius at a low speed, There is a drawback that the acceleration becomes large and the output of the engine is further reduced. Furthermore, even if the vehicle speed is taken into consideration in addition to lateral acceleration, even if the vehicle speed is taken into consideration, a point where the vehicle joins the fast-moving main line by turning left or right, commonly known as the T-road start Even if it is necessary to accelerate at approximately full throttle at the gear position, there is a risk that the output of the engine will be further reduced. In other words, even if the lateral acceleration is large, if the vehicle speed is low, or if the gear is a low speed, there is no danger of turning without decelerating.
In addition, even though the driver so desires, such driving control could not be performed. Therefore, in order to prevent this, there is no choice but to supplement the insufficient acceleration by manually switching the switch so that the above-mentioned operation control does not function.

The present invention has been made in view of the above-mentioned prior art, and further considers not only the lateral acceleration but also the vehicle speed and the shift speed, so that the driving feeling at the time of turning the vehicle is further within a safe range. An object of the present invention is to provide a vehicle turning control device that can be improved.

[0007]

The structure of the vehicle turning control device of the present invention which achieves the above object is a torque control means for reducing the driving torque of the engine independently of the operation by the driver, and A turning control unit that sets a target drive torque of the engine according to the magnitude of lateral acceleration applied to the vehicle and controls the operation of the torque control means so that the drive torque of the engine becomes the target drive torque. In the above vehicle, the target drive torque is set to be lower as the lateral acceleration becomes larger, and set to be higher as the vehicle speed of the vehicle becomes slower.
It is characterized in that it is set higher than in other gears.

If the driver operates the engine to set a high driving torque when the lateral acceleration applied to the vehicle during turning is large, it becomes dangerous because the driver cannot turn, and therefore it is not based on the operation of the driver. Independently, the torque control means reduces the output of the engine. Here, the operation of the torque control means is controlled by the turning control unit, and the turning control unit sets the target drive torque according to the lateral acceleration applied to the vehicle being turned, the vehicle speed, and the gear position, and the torque control means is set. To control. That is, the target drive torque is lowered as the lateral acceleration increases to ensure safety, while the target drive torque is not lowered when the vehicle speed is relatively low or in the case of the low speed shift stage. In other words, without slowing down,
Since the vehicle is turned as it is, the operation control is performed according to the situation, and the driving feeling is improved.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1 which shows the concept of an embodiment in which a vehicle turning control device according to the present invention is applied to a vehicle of a front-wheel drive type and FIG. 2 which shows a schematic structure of the vehicle, a combustion chamber of an engine 11 is shown. A throttle valve 15 for adjusting the opening amount of an intake passage 14 formed by the intake pipe 13 and adjusting the amount of intake air supplied into the combustion chamber 12 is incorporated in the middle of the intake pipe 13 connected to the valve 12. The throttle body 16 is interposed. As shown in FIG. 1 and FIG. 3 showing an enlarged cross-sectional structure of this cylindrical throttle body 16, both ends of a throttle shaft 17 having a throttle valve 15 integrally fixed thereto are rotatable on the throttle body 16. It is supported. An accelerator lever 18 and a throttle lever 19 are coaxially fitted to one end of the throttle shaft 17 protruding into the intake passage 14.

The throttle shaft 17 and the accelerator lever 1
Bush 21 and spacer 22
Is interposed, whereby the accelerator lever 18 is rotatable with respect to the throttle shaft 17. Further, a washer 23 and a nut 24 attached to one end side of the throttle shaft 17 allow the throttle shaft 17 to be released from the accelerator lever 18
It prevents from slipping out. An accelerator pedal 26 operated by a driver is connected to a cable receiver 25 integrated with the accelerator lever 18 via a cable 27, and the accelerator lever 18 is connected to the throttle shaft in accordance with the depression amount of the accelerator pedal 26. It is designed to rotate with respect to 17. On the other hand, the throttle lever 19 is fixed integrally with the throttle shaft 17,
Therefore, by operating the throttle lever 19, the throttle valve 15 rotates together with the throttle shaft 17. Further, a collar 28 is provided on the tubular portion 20 of the accelerator lever 18.
The throttle lever 19 is fitted coaxially therewith, and a stopper 30 is formed at the tip of the throttle lever 19 and can be engaged with a claw 29 formed in a part of the collar 28. The claw portion 29 and the stopper 30 are locked to each other when the throttle lever 19 is rotated in the direction in which the throttle valve 15 is opened or the accelerator lever 18 is rotated in the direction in which the throttle valve 15 is closed. It is set in a proper positional relationship.

Between the throttle body 16 and the throttle lever 19, a torsion coil spring 3 for pressing the stopper 30 of the throttle lever 19 against the claw 29 of the accelerator lever 18 to urge the throttle valve 15 in the opening direction.
1 is mounted coaxially with the throttle shaft 17 via a pair of cylindrical spring receivers 32, 33 fitted to the throttle shaft 17. Also, throttle body 1
Stopper pin 34 and accelerator lever 18 protruding from 6
Also between, and, the claw portion 29 of the accelerator lever 18 is pressed against the stopper 30 of the throttle lever 19 to urge the throttle valve 15 in the closing direction to give a detent feeling to the accelerator pedal 26. 35
Through the collar 28, the cylinder portion 2 of the accelerator lever 18
It is mounted coaxially with throttle shaft 17.

At the tip of the throttle lever 19,
A tip end of a control rod 38 having a base end fixed to a diaphragm 37 of the actuator 36 is connected. In the pressure chamber 39 formed in the actuator 36, the torsion coil spring 31 and the stopper 30 of the throttle lever 19 are pressed against the claw portion 29 of the accelerator lever 18 to urge the throttle valve 15 in the opening direction. 40
Is built in. And these two springs 31,
The spring force of the torsion coil spring 35 is set to be larger than the sum of the spring forces of 40, whereby the accelerator pedal 26 is depressed or the pressure in the pressure chamber 39 is adjusted by the spring force of the two springs 31, 40. The throttle valve 15 is not opened unless the negative pressure is larger than the sum of the above.

A surge tank 41 which is connected to the downstream side of the throttle body 16 and forms a part of the intake passage 14.
A vacuum tank 43 is connected to the vacuum tank 43 via a connection pipe 42. The vacuum tank 43 and the connection pipe 42 are connected to each other.
Between the vacuum tank 43 and the surge tank 4
A non-return valve 44 is provided which allows only air movement to 1. As a result, the pressure in the vacuum tank 43 is set to a negative pressure substantially equal to the minimum pressure in the surge tank 41.

The inside of the vacuum tank 43 and the pressure chamber 39 of the actuator 36 are in communication with each other through a pipe 45, and in the middle of the pipe 45, there is a closed type non-energized first torque control. A solenoid valve 46 is provided. That is, the torque control solenoid valve 46 has a pipe 45.
A spring 49 that urges the plunger 47 toward the valve seat 48 so as to close the valve is incorporated.

The pipe 45 between the first torque control solenoid valve 46 and the actuator 36 is connected to the intake passage 14 upstream of the throttle valve 15.
Are connected. A second torque control solenoid valve 51 that is open when not energized is provided in the middle of the pipe 50. In other words, the torque control solenoid valve 51 is provided with a spring 5 for biasing the plunger 52 so as to open the pipe 50.
3 is incorporated.

The two torque control solenoid valves 46, 51
An electronic control unit 54 (hereinafter, referred to as an ECU) that controls the operating state of the engine 11 is connected to each of the above, and the energization of the torque control solenoid valves 46 and 51 is turned on based on a command from the ECU 54. , OFF is duty-controlled, and in the present embodiment, the torque control means of the present invention is constituted by them as a whole.

For example, when the duty ratio of the torque control solenoid valves 46 and 51 is 0%, the pressure chamber 39 of the actuator 36 is located upstream of the throttle valve 15 in the intake passage 14.
The atmospheric pressure becomes almost equal to the internal pressure, and the throttle valve 15
The opening degree corresponds to the depression amount of the accelerator pedal 26 on a one-to-one basis. On the contrary, when the duty ratio of the torque control solenoid valves 46 and 51 is 100%, the pressure chamber 39 of the actuator 36 becomes a negative pressure almost equal to the pressure in the vacuum tank 43, and the control rod 38 is slanted to the left in FIG. As a result of being pulled upward, the throttle valve 15 is closed regardless of the depression amount of the accelerator pedal 26, and the drive torque of the engine 11 is forcibly reduced. In this way
By adjusting the duty ratios of the torque control solenoid valves 46 and 51, the opening degree of the throttle valve 15 can be changed regardless of the depression amount of the accelerator pedal 26, and the drive torque of the engine 11 can be adjusted arbitrarily.

The ECU 54 has a crank angle sensor 55 attached to the engine 11 for detecting the engine speed,
A throttle opening sensor 56 attached to the throttle body 16 for detecting the opening of the throttle lever 19;
It is connected to an idle switch 57 that detects the fully closed state of the throttle valve 15, and output signals from the crank angle sensor 55, the throttle opening sensor 56, and the idle switch 57 are sent respectively.

A torque calculation unit for calculating the target drive torque of the engine 11 (hereinafter referred to as TCL).
An throttle opening sensor 56 and an idle switch 57 are mounted on the throttle body 16 to detect the opening of the accelerator lever 18, and an open front wheel 60 and a pair of left and right front wheels 60, 61.
Front wheel rotation sensors 62, 6 for detecting the respective rotation speeds of the
3, rear wheel rotation sensors 66 and 67 for detecting the rotational speeds of the pair of left and right rear wheels 64 and 65, which are driven wheels, respectively, and the steering shaft 6 during turning based on the straight traveling state of the vehicle 68.
9 is connected to a steering angle sensor 70 for detecting a turning angle, and output signals from these sensors 59, 62, 63, 66, 67, 70 are sent respectively.

The ECU 54 and the TCL 58 are connected via a communication cable 71. The ECU 54 provides information on the operating state of the engine 11, such as the engine speed and the detection signal from the idle switch 57, as well as the intake air amount. Sent to TCL 58. Conversely, the TCL 58 sends information about the target drive torque calculated by the TCL 58 to the ECU 54.

As shown in FIG. 4, which shows a rough flow of control according to the present embodiment, in the present embodiment, the target drive torque T _OS of the engine 11 when slip control is performed and the friction coefficient such as a dry road are performed. Of the target drive torque T _OH of the engine 11 when the turning control is performed on a relatively high road surface (hereinafter, referred to as a high μ road) and a relatively high friction coefficient such as a frozen road or a wet road. Target drive torque T of the engine 11 when turning control is performed on a low road surface (hereinafter referred to as a low μ road)
_OL and TCL58 are always calculated in parallel, and the optimum final target drive torque T _O is selected from these three target drive torques T _OS , T _OH , and T _OL, and the drive torque of the engine 11 is set as necessary. I am trying to reduce it.

Specifically, the control program of this embodiment is started by turning on an ignition key (not shown). First, at M1, the initial value δ _{m (0)} of the steering shaft turning position is read and various flags are set. Initialization such as resetting or starting the count of the main timer every 15 milliseconds which is the sampling period of this control is performed.

Then, in M2, the TCL 58 calculates the vehicle speed V and the like based on the detection signals from various sensors, and subsequently, the neutral position δ _M of the steering shaft 69 is learned and corrected in M3. Neutral position [delta] _M of the steering shaft 69 of the vehicle 68, wherein at the initial value [delta] _{m (0)} is read each time the ignition key turned on, the initial value [delta] _{m (0)} is the vehicle 68 will be described later straight Learning correction is performed only when the driving condition is satisfied, and this initial value δ is maintained until the ignition key is turned off.
_{m (0)} is learned and corrected.

Next, the TCL 57 is M4 and the front wheels 60 and 6 are connected.
The target drive torque T _OS in the case of performing the slip control for restricting the drive torque of the engine 11 is calculated based on the rotation difference between the rear wheel 64 and the rear wheels 64 and 65, and the turning control on the high μ road is performed at M5. In the case where the target drive torque T _OH of the engine 11 is calculated and the turning control on the low μ road is similarly performed in M6, the engine 1
The target drive torque T _OL of 1 is sequentially calculated.

Then, in M7, the TCL 57 selects an optimum final target drive torque T _O from these target drive torques T _OS , T _OH and T _OL by the method described later, and then the drive torque of the engine 11 is set to the final target torque. The ECU 54 controls the pair of torque control solenoid valves 46 and 51 so that the driving torque T _O is obtained.
The duty ratio is controlled so that the vehicle 68 can be driven reasonably and safely. in this way,
The drive torque of the engine 11 is controlled at M8 until the countdown of the main timer ends, and thereafter, the countdown of the main timer is restarted at M9, and the steps from M2 to M9 are performed with the ignition key turned off. Repeat until.

The reason why the neutral position δ _M of the steering shaft 69 is learned and corrected in the step of M3 is that the front wheels 6 are maintained when the vehicle 68 is serviced.
A deviation between the turning amount of the steering shaft 69 and the actual steering angle δ of the front wheels 60, 61, which are the steered wheels, may occur due to secular change such as wear adjustment of a steering gear (not shown) when the toe-in adjustment of 0, 61 is performed. This is because the neutral position δ _M of the steering shaft 69 may change when it occurs. As shown in FIG. 5 showing the procedure for learning and correcting the neutral position δ _M of the steering shaft 69, TC
L58 calculates the vehicle speed V at C1 by the following equation (1) based on the detection signals from the rear wheel rotation sensors 66 and 67. V = (V _RL + V _RR ) / 2 (1) However, in the above equation, V _RL and V _RR are the peripheral speeds of the pair of left and right rear wheels 64 and 65, respectively.

Next, the TCL 58 calculates a peripheral speed difference (hereinafter referred to as a rear wheel speed difference) | V _RL -V _RR | between the pair of left and right rear wheels 64 and 65 at C2. After that, TCL
At 58, it is determined at C3 whether the vehicle speed V is higher than a preset threshold value V _A. If the vehicle 68 does not reach a high speed to some extent, this operation requires the rear wheel speed difference due to steering | V _RL -V
_RR | and the like are necessary because they cannot be detected, and the threshold value V _A is appropriately set, for example, at 20 km / h by an experiment based on the traveling characteristics of the vehicle 68 and the like.

When it is determined that the vehicle speed V is equal to or higher than the threshold value V _A , the TCL 58 causes the rear wheel speed difference | V _RL at C4.
It is determined whether −V _RR | is smaller than a preset threshold value V _B such as 0.1 km / hour, that is, whether the vehicle 68 is in a straight traveling state. Here, the threshold value V _{B is set} to 0 km / h.
The reason is that, when the tire pressures of the left and right rear wheels 64, 65 are not equal, the circumferential speeds V _RL , V _{RR of the} left and right rear wheels 64, 65 are different even though the vehicle 68 is in a straight traveling state. The reason is that

At this step C4, the rear wheel speed difference | V _RL −
If it is determined that V _RR | is less than or equal to the threshold value V _B , then TCL
In C5, the current steering axis turning position δ _{m (n)} is the previous steering axis turning position δ _{m (n-1)} detected by the steering angle sensor 70 at C5.
Is determined to be the same as. At this time, the steering angle sensor 70 should not be affected by the shake of the driver.
It is desirable to set the turning detection resolution of the steering shaft 69 by about 5 degrees, for example.

If it is determined in step C5 that the current steering axis turning position δ _{m (n)} is the same as the previous steering axis turning position angle δ _{m (n-1)} , the TCL 58 determines in C6. It is determined that the current vehicle 68 is in a straight traveling state, and the counting of a learning timer (not shown) incorporated in the TCL 58 is started,
This is continued for 0.5 seconds, for example. Next, TCL58 is C
In step 7, it is determined whether or not 0.5 seconds has elapsed from the start of counting by the learning timer, that is, whether or not the straight traveling state of the vehicle 68 has continued for 0.5 seconds. In this case, since 0.5 seconds has not elapsed from the start of counting the learning timer at the beginning of traveling of the vehicle 68, the steps C1 to C7 are repeated at the beginning of traveling of the vehicle 68.

From the start of counting the learning timer
When it is judged that 0.5 seconds have elapsed, TCL58 will set C8.
At, it is determined whether the steering angle neutral position learned flag F _H is set, that is, whether the current learning control is the first time. If it is determined in step C8 that the steering angle neutral position learned flag F _H is not set, then C9
At this point, the current steering shaft turning position δ _{m (n)} is regarded as the new steering shaft 69 neutral position δ _{M (n)} , this is read into the memory in the TCL 58, and the steering angle neutral position learned flag F _H is set. To do.

After the new neutral position δ _{M (n)} of the steering shaft 69 is set in this way, the turning angle δ _H of the steering shaft 69 is set with reference to the neutral position δ _{M (n)} of the steering shaft 69. While calculating, the count of the learning timer is cleared at C10, and the steering angle neutral position learning is performed again.

If it is determined in step C8 that the steering angle neutral position learned flag F _H has been set, that is, the steering angle neutral position learning has been performed for the second time or later, TCL58
At C11, the current steering shaft turning position δ _{m (n)} is _equal to the previous steering shaft 69 neutral position δ _{M (n-1)} , that is, δ _{m (n)} = δ
Determine if it is _{M (n-1)} . Then, the current steering shaft turning position δ _{m (n)} is the neutral position δ of the previous steering shaft 69.
If it is determined that it is equal to _{M (n-1)} , the process directly returns to the step C10 and the next steering angle neutral position learning is performed again.

In step C11, it is determined that the current steering shaft turning position δ _{m (n)} is not equal to the previous steering shaft 69 neutral position δ _{M (n-1)} due to play in the steering system. if you did this,
The current steering axis turning position δ _{m (n)} remains unchanged and the new steering axis 6
9 neutral position δ _{M (n),} and if the absolute value of these differences differs by a preset correction limit amount Δδ or more, the neutral position δ _{M (n- A} new neutral position δ _{M (n) of the} steering shaft 69 is obtained by subtracting or adding the correction limiting amount Δδ from ₁₎ , and this is read into the memory in the TCL 58.

That is, the TCL 58 at C12 moves from the current steering shaft turning position δ _{m (n)} to the previous neutral position δ of the steering shaft 69.
_The value obtained by subtracting _{M (n-1)} is the preset negative correction limit-Δ
It is determined whether it is smaller than δ. And this C12
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 69 is set to the neutral position of the previous steering shaft 69 in C13. The position δ _{M (n-1)} and the negative correction limit amount −Δδ are changed as follows so that the learning correction amount per time does not unconditionally increase to the negative side. δ _{M (n)} = δ _{M (n-1) −} Δδ

As a result, even if the steering angle sensor 70 outputs an abnormal detection signal for some reason,
The neutral position δ _M of the steering shaft 69 does not change abruptly, and this abnormality can be quickly dealt with. On the other hand, C1
When it is determined that the value subtracted in step 2 is larger than the negative correction limit amount −Δδ, the neutral position δ of the steering shaft 69 from the current steering shaft turning position δ _{m (n)} to the previous steering shaft 69 at C14.
_It is determined whether the value obtained by subtracting _{M (n-1)} is larger than the positive correction limit amount Δδ. When it is determined that the value subtracted in step C14 is larger than the positive correction limit amount Δδ, a new neutral position δ of the steering shaft 69 is obtained in C15.
_{M (n)} is changed from the previous neutral position δ _{M (n-1)} of the steering shaft 69 and the positive correction limit amount Δδ as follows, and the learning correction amount per time is unconditionally moved to the positive side. Care is taken not to grow. δ _{M (n)} = δ _{M (n-1)} + Δδ

As a result, even if the steering angle sensor 70 outputs an abnormal detection signal for some reason,
The neutral position δ _M of the steering shaft 69 does not change abruptly, and this abnormality can be quickly dealt with. However, C1
When it is determined that the value subtracted in step 4 is smaller than the positive correction limit amount Δδ, the current steering shaft turning position δ _{m (n) is changed} to the neutral position δ _M of the new steering shaft 69 in C16. Read as it is as _(n) .

Therefore, when the stopped vehicle 68 starts with the front wheels 60, 61 kept in the turning state, as shown in FIG. 6, which shows an example of the changing state of the neutral position δ _M of the steering shaft 69 at this time. When the learning control of the neutral position δ _M of the steering shaft 69 is the first time, the correction amount from the initial value δ _{m (0)} of the steering shaft turning position in the step of M1 described above becomes very large, but the second time. Thereafter, the neutral position δ _M of the steering shaft 69 is C13,
The operation is suppressed by the operation in the step C14.

In this way, the neutral position δ _{M of the} steering shaft 69
After learning correction, the vehicle speed V and the peripheral speed V of the front wheels 60, 61
Based on the difference between _FL and V _FR , the target drive torque T _OS when performing the slip control for restricting the drive torque of the engine 11 is calculated. By the way, in order to effectively operate the driving torque generated in the engine 11, the friction coefficient between the tire and the road surface,
As shown in FIG. 7, which shows the relationship with the slip ratio of the tire, the slip ratio S of the tires of the front wheels 60 and 61 during traveling is S.
However, the slip amount S of the front wheels 60, 61 is adjusted so that the target slip ratio S _O corresponding to the maximum value of the friction coefficient between the tire and the road surface or the vicinity thereof is adjusted so as not to impair the acceleration performance of the vehicle 68. Is desirable.

Here, the tire slip ratio S is expressed by the following equation, and the slip ratio S is set to the target slip ratio S _O corresponding to the maximum value of the friction coefficient between the tire and the road surface or its vicinity, The target drive torque T _OS of the engine 11 is set, and the calculation procedure is as follows. S = {(V _FL + V _FR ) / 2−V} / V First, the TCL 58 calculates the current vehicle speed V _(n) calculated by the equation (1) and the vehicle speed V _(n-1) calculated one time before. From the above, the present longitudinal acceleration G _X of the vehicle 68 is calculated by the following equation. _{G X = (V (n)} -V (n-1)) /3.6 · Δt · g where, Delta] t is the sampling period of the main timer 15 ms, g is the gravitational acceleration.

Then, the driving torque T of the engine 11 at this time
_B is calculated by the following formula (2). T _B = G _XF · W _b · r + T _R (2) Here, G _XF is a corrected longitudinal acceleration that has passed through a low-pass filter that delays the change in the longitudinal acceleration G _X described above. The low-pass filter, the coefficient of friction and because it can be regarded as equivalent, the slip ratio S tires and the road surface of the tire longitudinal acceleration G _X is changed in the vehicle 68 of the longitudinal acceleration G _X is a tire of the vehicle and the road surface 68 Even if the target slip ratio S 0 corresponding to the maximum value of the friction coefficient between the tire and the road is about to deviate from the target slip ratio S _O , the slip ratio S of the tire is changed to the target slip ratio S corresponding to the maximum value of the friction coefficient between the tire and the road surface.
_Longitudinal acceleration G _X to maintain _O or its vicinity
Has the function of correcting Further, W _b is the weight of the vehicle body, r is the effective radius of the front wheels 60 and 61, and _Tr is running resistance. This running resistance _Tr can be calculated as a function of the vehicle speed V. It is calculated from the map as shown in.

On the other hand, when the vehicle 68 is accelerating, the slip amount of the wheels is usually about 3% with respect to the road surface, and when traveling on a bad road such as a gravel road, Low μ
The maximum value of the friction coefficient between the tire and the road surface, which corresponds to the target slip ratio S _O , is generally larger than when traveling on the road. Therefore, the target drive wheel speed V _F0 , which is the peripheral speed of the front wheels 60 and 61, is calculated by the following formula (3) in consideration of the slip amount and the road surface condition. _{V F0 = 1.03 · V N +} V K ... (3)

[0043] However, V _K is road correction amount set in advance corresponding to the corrected longitudinal acceleration G _XF, to have a tendency to increase stepwise as the value of the correction longitudinal acceleration G _XF increases However, in this embodiment, the road surface correction amount V _K is obtained from the map as shown in FIG. 9 created based on the running test or the like. Next, the vehicle speed V and the target drive wheel speed V _F0
The slip amount S, which is the difference from the above, is calculated by the following equation (4) based on the equations (1) and (3). S = (V _FL + V _FR ) / 2−V _F0 (4) Then, as shown in the following equation (5), this slip amount S is integrated while being multiplied by the integration coefficient K _I at each sampling cycle of the main timer. , Integral correction torque T _I (however, T _I ≦ 0) for improving control stability with respect to target drive torque T _OS
Is calculated. T ₁ = ΣK ₁ · S (i) (5) (However, it is the sum total for i = 1 to n.)

Similarly, the slip amount ΔV is expressed by the following equation (6).
The proportional correction torque T _P for reducing the control delay with respect to the target drive torque T _OS proportional to is calculated while being multiplied by the proportional coefficient K _P. T _P = K _P · S (6) Then, the target drive torque T _OS of the engine 11 is calculated by the following equation (7) using the equations (2), (5) and (6). _{T OS = (T B -T I} -T P + T R) / ρ m · ρ d ... (7) the transmission ratio of the upper (not shown) [rho _m in type transmission, the [rho _d is a reduction ratio of the differential gear. The vehicle 68 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, the slip control operation described below is performed. I do.

FIG. 1 showing the flow of this slip control process.
As shown in 0, the TCL 58 first detects the target drive torque T by performing the detection and calculation processing of various data described above in S1.
_{Although the OS} is calculated, this calculation operation is performed regardless of the operation of the manual switch. Next, in S2, it is determined whether or not the slip control flag F _S is set.
At first, since the slip control flag F _S is not set, the TCL 58 determines in S3 whether the slip amount S of the front wheels 60, 61 is larger than a preset threshold value, for example, 2 km / hour. If it is determined in step S3 that the slip amount S is greater than 2 km / h, TCL58
Determines whether the rate of change .DELTA.G _S slip amount S is greater than 0.2 g at S4.

[0046] If it is determined that the step at the slip rate of change .DELTA.G _S of S4 is greater than 0.2 g, and sets in the slip control flag F _S at S5, the slip control flag F _S is set at S6 It is again determined whether or not In this step S6, the slip control flag F
_S is the case it is determined that the system is in set employs a target driving torque T _OS for slip control in advance calculated by the equation (7) as the target driving torque T _OS of the engine 11 at S7. If it is determined in step S6 that the slip control flag F _S has been reset, TCL
58 outputs the maximum torque of the engine 11 as the target drive torque T _OS at S8, whereby the ECU 54 reduces the duty ratio of the torque control solenoid valves 46 and 51 to the 0% side. As a result, the engine 11 is operated by the driver. A drive torque is generated according to the amount of depression of the accelerator pedal 26. In the step of S8, the TCL 58 outputs the maximum torque of the engine 11 because the ECU 54 always sets the duty ratio of the torque control solenoid valves 46 and 51 to 0 from the viewpoint of control safety and the like.
This is because the engine 11 is operated so as to cut off the energization to the% side, that is, the torque control solenoid valves 46 and 51, so that the engine 11 surely generates the driving torque according to the depression amount of the accelerator pedal 26 by the driver.

When it is determined in step S3 that the slip amount S of the front wheels 60 and 61 is smaller than 2 km / h,
Alternatively, the slip amount change rate G _S is 0.2 in the step S4.
When it is determined that the value is smaller than g, the above S6 is directly performed.
And the TCL 58 sets the target drive torque T _OS.
As a result, the maximum torque of the engine 11 is output in step S8, and the ECU 54 causes the torque control solenoid valve 46,
As a result of reducing the duty ratio of 51 to 0%, the engine 1
1 generates a driving torque according to the amount of depression of the accelerator pedal 26 by the driver. On the other hand, if it is determined in step S2 that the slip control flag F _S is set, it is determined in step S9 whether the idle switch 57 is on, that is, the throttle valve 15 is fully closed. judge.

When it is determined in step S9 that the idle switch 57 is on, the driver has not stepped on the accelerator pedal 26, so the slip control flag F _S is reset in step S10, and the step S6 is executed. Move to. Also, in step S9, the idle switch 5
When it is determined that 7 is off, it is determined again in step S6 whether or not the slip control flag F _S is set. When the driver does not operate the manual switch for selecting the slip control, the TCL 58 calculates the target drive torque T _OS for the slip control as described above and then the engine 11 when the turning control is performed. Calculate the target drive torque. When controlling the turning of the vehicle 68,
The TCL 58 determines the vehicle 6 from the steering axis turning angle δ _H and the vehicle speed V.
The target lateral acceleration G _YO of 8 is calculated, and the acceleration in the vehicle front-rear direction, that is, the target longitudinal acceleration G _XO so that the vehicle 68 does not undergo extreme _{understeering,} is calculated as the target lateral acceleration G _YO.
Set based on. And this target longitudinal acceleration G _XO
The target drive torques of the engine 11 corresponding to are calculated, and these target drive torques are output to the ECU 54.

The lateral acceleration G _Y of the vehicle 68 can be actually calculated by using the rear wheel speed difference | V _RL −V _RR |, but the vehicle 68 can be calculated by using the steering shaft turning angle δ _H. Since it is possible to predict the value of the lateral acceleration G _Y that acts on, there is an advantage that quick control can be performed. However, if the target drive torque of the engine 11 is simply obtained from the steering shaft turning angle δ _H and the vehicle speed V, the driver's intention is not reflected at all, and the driver may be dissatisfied with respect to the maneuverability of the vehicle 68. There is. Therefore, calculated required driving torque T _d of the engine 11 that the driver wants the depression amount of the accelerator pedal 26, it is desirable to set the target drive torque of the engine 11 in consideration of the required driving torque T _d . Further, when the increase / decrease amount of the target drive torque of the engine 11 set every 15 milliseconds is very large, a shock occurs due to the acceleration / deceleration of the vehicle 68, which causes a reduction in riding comfort. When the increase / decrease amount of the target drive torque 11 is large enough to cause a reduction in the riding comfort of the vehicle 68, it is also necessary to regulate the increase / decrease amount of the target drive torque.

Further, unless the target drive torque of the engine 11 is changed depending on whether the road surface is a high μ road or a low μ road, for example, the engine 11 is driven with a target drive torque for a high μ road while traveling on a low μ road.
If the vehicle is driven, the front wheels 60 and 61 may slip and safe driving may become impossible.
It is desirable to calculate the target drive torque T _OH for the high μ road and the target drive torque T _OL for the low μ road respectively.
As shown in FIG. 11 showing a calculation block of a turning control for a high μ road in consideration of the above knowledge, the TCL 58 determines the vehicle speed V from the outputs of the pair of rear wheel rotation sensors 66 and 67.
The steering angle δ of the front wheels 60, 61 is calculated by the following formula (8) based on the detection signal from the steering angle sensor 70, and the target lateral acceleration G _YO of the vehicle 68 at this time is calculated by the formula (1). formula
Calculated according to (9). δ = δ _H / ρ _H (8) G _YO = δ / ω (A + 1 / V ² ) (9) where ρ _H is the steering gear speed ratio, ω is the wheel base of the vehicle 68, and A is the vehicle star. It is a capability factor.

As is well known, the stability factor A is a value determined by the configuration of the suspension system of the vehicle 68, the tire characteristics, and the like. Specifically, the actual lateral acceleration G _Y generated in the vehicle 68 during a steady circular turn and the steering angle ratio δ _H / δ _HO of the steering shaft 69 at this time (the neutral position δ _{M of the} steering shaft 69).
The ratio of the turning angle δ _HO of the steering shaft 69 to the turning angle δ _H of the steering shaft 69 at the time of acceleration at which the lateral acceleration G _Y is close to 0 based on It is expressed as the slope of the tangent in the graph shown in FIG. That is, in a region where the lateral acceleration G _Y is small and the vehicle speed V is not too high, the stability factor A has a substantially constant value (A = 0.002), but the lateral acceleration G _Y is 0.
When the weight exceeds 6 g, the stability factor A increases sharply, and the vehicle 68 exhibits an extremely strong understeering tendency.

From the above, based on FIG. 12, the stability factor A is set to 0.002 or less, and the target lateral acceleration G of the vehicle 68 calculated by the equation (9) is calculated.
The drive torque of the engine 11 is controlled so that _YO is less than 0.6 g. When the target lateral acceleration G _YO is calculated in this way, the target longitudinal acceleration G _XO of the vehicle 68 set in advance according to the magnitude of the target lateral acceleration G _YO and the vehicle speed V is T.
It is obtained from a map as shown in FIG. 13 which is stored in the CL 58 in advance. As shown by the solid line in FIG. 13, the lateral acceleration G of the vehicle
_{When Y} is large, the target longitudinal acceleration G _XO is set low to improve safety. On the other hand, even if the vehicle speed is low, even if the lateral acceleration G _{Y of the} vehicle is large,
If the target longitudinal acceleration G _XO is set low and further decelerated, not only the safety is not improved, but also the driving feeling is impaired. Therefore, the lower the vehicle speed V, the higher the target longitudinal acceleration G _XO . That is, if the target lateral acceleration G _YO is constant, the target longitudinal acceleration G _XO increases as the vehicle speed V _decreases .

Further, as indicated by a broken line in FIG. 13, when the vehicle speed V is within the first gear range, for example, 60 km / h or less and the gear stage is the first gear, the map threshold value is set to about 0.25
g higher. Therefore, if the vehicle speed V is below a certain value,
If the gear is the first gear, the other gear, that is, 2
The target longitudinal acceleration G _XO becomes larger than that in the case of the third gear or the like. Therefore, in the case of full acceleration while turning at the first speed from the stopped state, it is possible to accelerate with a driving feeling close to the driver's intention. Instead of increasing the threshold value of the map by about 0.25 g as shown by the broken line in FIG. 13, as shown in FIG. 11, when the vehicle speed V is equal to or lower than a certain value and the gear stage is the first gear stage. , By subtracting about 0.25 g from the target lateral acceleration G _YO , even if this is underestimated, the same effect can be obtained.

Target longitudinal acceleration G _XO thus obtained
The reference drive torque T _B of the engine 11 is calculated by the following equation (10). T _B = (G _XO · W _b · r + T _L ) / ρ _m · ρ _d (10) where T _L is the road surface resistance obtained as a function of the lateral acceleration G _Y of the vehicle 68. Load) torque, which is obtained from the map shown in FIG. 14 in this embodiment.

Next, in order to determine the adoption ratio of reference driving torque T _B, obtains the correction reference driving torque by multiplying the weighting coefficients α to the reference driving torque T _B. The weighting coefficient α is set empirically by turning the vehicle 68, but on a high μ road, a value around 0.6 is adopted.

On the other hand, the required drive torque T _d desired by the driver is shown in FIG. 15 based on the engine speed N _E detected by the crank angle sensor 55 and the accelerator opening θ _A detected by the accelerator opening sensor 59. Obtained from the map as shown in
Next, the correction required drive torque corresponding to the weighting coefficient α is calculated by multiplying the required drive torque T _d by (1-α). For example, when α = 0.6 is set, the adoption ratio of the reference drive torque T _B and the desired drive torque T _d is 6: 4. Therefore, the target drive torque T _OH of the engine 11 is calculated by the following equation (11). T _OH = α ・ T _B + (1-α) ・ T _d (11)

The vehicle 68 is provided with a manual switch (not shown) for the driver to select the turning control for the high μ road, and the driver operates this manual switch to control the turning for the high μ road. When is selected, the turning control operation for the high μ road described below is performed. As shown in FIG. 16 showing a flow of control for determining a target driving torque T _OH of the high μ road turning control, the detection and processing of various data described above in H1, the target driving torque T _OH
Is calculated, but this operation is performed regardless of the operation of the manual switch.

Next, at H2, it is determined whether the vehicle 68 is in the turning control on the high μ road, that is, the high μ road turning control flag F.
Determine if _CH is set. High μ at first
Since the road turning control is not being performed, the high μ road turning control flag F
It is determined that _CH is in the reset state, and it is determined at H3 whether the target drive torque T _OH is equal to or less than a preset threshold value (T _d −2). That is, the target drive torque T _OH can be calculated even when the vehicle 68 is traveling straight, but the value is usually much larger than the drive torque T _d requested by the driver. However, this required drive torque T _d is
Since it generally decreases during the turning, the time when the target drive torque T _OH becomes equal to or less than the threshold value (T _d -2) is determined as the starting condition of the turning control. The threshold is set to (T _d -2) as a hysteresis for preventing control hunting.

At step H3, the target drive torque T_OHBut
Threshold (T_d-2) If it is determined that
H4 determines if the idle switch 57 is off.
Set. In this H4 step, idle switch 57
Is off, that is, the accelerator pedal 26 is
When it is determined that the vehicle is being stepped on, turn on a high μ road at H5
Controlling flag F_CHIs set. Next, the steering angle at H6
Neutral position learned flag F _HWhether is set,
That is, the credibility of the steering angle δ detected by the steering angle sensor 70.
Sex is determined.

If it is determined in step H6 that the steering angle neutral position learned flag F _H is set, it is again determined in step H7 whether the high μ road turning control flag F _CH is set. . In the above procedure, since the high μ road turning control flag F _CH is set at step H5,
At step H7, it is determined that the high μ road turning control flag F _CH is set, and at H8, the previously calculated value, that is, H
The target drive torque T _{OH in} step 1 is used as it is. On the other hand, if step at the steering angle neutral position learned flag F _H of the H6 is judged not to be set, (8)
Since there is no credibility of the steering angle δ calculated by the formula, the target drive torque T _OH calculated by the formula (11) is not adopted and TCL5
8 outputs the maximum torque of the engine 11 as the target drive torque T _OH at H9, which causes the ECU 54 to reduce the duty ratio of the torque control solenoid valves 46, 51 to the 0% side. A drive torque is generated according to the amount of depression of the accelerator pedal 26.

If it is determined in step H3 that the target drive torque T _OH is not equal to or less than the threshold value (T _d -2), the process does not shift to the turning control and the process from step H6 or H7 to step H9 is performed.
And the TCL 58 sets the target drive torque T _OH.
The maximum torque of the engine 11 is output as
As a result of U54 lowering the duty ratio of the torque control solenoid valves 46, 51 to the 0% side, the engine 11 generates a drive torque according to the amount of depression of the accelerator pedal 26 by the driver. Similarly, when the idle switch 56 is turned on in step H4, that is, when it is determined that the accelerator pedal 26 is not depressed by the driver, TCL5
8 outputs the maximum torque of the engine 11 as the target drive torque T _OH , which causes the ECU 54 to control the torque control solenoid valve 4
As a result of lowering the duty ratios of 6 and 51 to the 0% side, the engine 11 generates a drive torque according to the amount of depression of the accelerator pedal 26 by the driver and does not shift to the turning control.

If it is determined in step H2 that the high μ road turning control flag F _CH is set, H
10 determines whether the difference ΔT between the target driving torque calculated time T _OH and the target driving torque T _OH previously calculated _(n-1) is larger than the increase or decrease the allowable amount T _K which is set in advance at. This increase / decrease allowable amount T _K is a torque change amount that does not make an occupant feel an acceleration / deceleration shock of the vehicle 68. For example, when it is desired to suppress the target longitudinal acceleration G _XO of the vehicle 68 to 0.1 g per second,
Using equation (10), the following is obtained. The difference between _{T K = 0.1 · W b ·} r · Δt / ρ M · ρ D target driving torque calculated this time by the H10 Step T _OH and the target driving torque T _OH previously calculated _{(n-1) Δ}
When it is determined that T is not larger than the preset allowable increase / decrease amount T _K , the difference ΔT between the target drive torque T _OH and the previously calculated target drive torque T _{OH (n-1)} is negative at H11. It is determined whether or not it is larger than the increase / decrease allowable amount T _{K of}

At step H11, the target drive torque T _OH
And the difference ΔT between the target driving torque T _OH previously calculated _(n-1) is determined to be larger than the negative decrease tolerance T _K, the target driving torque T _OH was calculated target driving torque T _OH and previously calculated time absolute value of the difference _(n-1) and | [Delta] T | is increased or decreased tolerance T _K
The target drive torque T calculated this time is smaller than
_OH is adopted as it is as the calculated value in the step of H8. Further, if it is determined that the difference ΔT between the target driving torque calculated time T _OH and the target driving torque T _OH previously calculated _(n-1) in H11 in step is not greater than the negative decrease tolerance T _K, H12 At this time, the target drive torque T _OH of this time is corrected by the following formula, and this is adopted as the calculated value in the step of H8. T _OH = T _{OH (n−1)} −T _K That is, the reduction amount with respect to the target drive torque T _{OH (n−1)} calculated last time is regulated by the increase / decrease allowable amount T _K , and the deceleration accompanying the reduction of the drive torque of the engine 11 is performed. Reduce the shock.

[0064] On the other hand, it is determined that the difference ΔT between the H10 target driving torque calculated this time in step T _OH and the target driving torque T _OH previously calculated _(n-1) is increased or decreased tolerance T _K or higher Then, the target drive torque T _OH of this time is corrected by the following formula in H13, and this is adopted as the calculated value in the step of H8. T _OH = T _{OH (n-1)} + T _{K In other} words, even when the drive torque increases, the target drive torque T _OH calculated this time and the target drive torque T _{OH (} previously calculated) are the same as when the drive torque decreases. If _{the n-1)} difference between ΔT exceeds the decrease tolerance T _K restricts gains at decreasing tolerance T _K for the target driving torque T _OH previously calculated _(n-1), the driving of the engine 11 The acceleration shock accompanying the torque increase is reduced.

In this way, the steering shaft turning angle δ _H and the target longitudinal acceleration G when the increase / decrease amount of the target drive torque T _OH is restricted
_As shown in FIG. 17 in which the change state of _XO , the target drive torque T _OH, and the actual longitudinal acceleration G _X is represented by a broken line, it is more actual than the case where the amount of increase or decrease of the target drive torque T _OH is not regulated by a solid line It can be seen that the change in the longitudinal acceleration G _X is smooth and the acceleration / deceleration shock has been resolved. When the target drive torque T _OH is set as described above, the TCL 58 determines in H14 whether this target drive torque T _OH is larger than the driver's required drive torque T _d . Here, when the high μ road turning control in-progress flag F _CH is set, the target drive torque T _OH is not larger than the driver's requested drive torque T _d , and therefore the idle switch 57 is turned on at H15. To determine.

If it is determined in step H15 that the idle switch 57 is not in the ON state, it means that the turning control is required, and therefore the process proceeds to step H6. Further, if it is determined in step H14 that the target drive torque T _OH is larger than the driver's required drive torque T _d , it means that the turning traveling of the vehicle 68 has ended. The μ road turning control flag F _CH is reset. Similarly, when it is determined in step H15 that the idle switch 57 is in the ON state, it means that the accelerator pedal 26 is not depressed. Therefore, the routine proceeds to step H16, where the high μ road turning control in progress flag F is performed. Reset _CH .

At this H16, the high-μ road turning control flag F
_{When CH} is reset, TCL58 will set the target drive torque T
The maximum torque of the engine 11 is output at H9 as _{OH, and} as a result, the ECU 54 reduces the duty ratio of the torque control solenoid valves 46, 51 to the 0% side. As a result, the engine 11 causes the accelerator pedal 26 to be depressed by the driver. Generates a drive torque according to the. After calculating the target drive torque T _OH for the high μ road turning control, the TCL 58 calculates the target drive torque T _OL for the low μ road turning control as follows. Incidentally, since the actual large value towards the lateral acceleration G target than _Y lateral acceleration G _Y0 at low μ road, it determines whether the target lateral acceleration G _Y0 is greater than a predetermined threshold value, the target lateral If the acceleration G _Y0 is greater than this threshold, the vehicle 68
Is determined to be traveling on a low μ road, and turning control may be performed if necessary.

As shown in FIG. 18 which shows the calculation block of the turning control for the low μ road, the target lateral acceleration G _YO is calculated from the steering shaft turning angle δ _H and the vehicle speed V by the above equation (9). As the stability factor A of, for example, 0.005 is adopted. Next, the target longitudinal acceleration G _XO is obtained from the target lateral acceleration G _YO and the vehicle speed V. In the present embodiment, the target longitudinal acceleration G _XO is read from the map shown in FIG. This map shows the target longitudinal acceleration G _XO so that the vehicle 68 can travel safely according to the magnitude of the target lateral acceleration G _YO.
Is related to the vehicle speed V and is set based on the test traveling result and the like. Here, as shown in FIG. 19, if the target lateral acceleration G _YO is constant, the target longitudinal acceleration G _XO increases as the vehicle speed V _decreases . Further, when the vehicle speed is equal to or lower than a certain value and the shift speed is the first speed, the threshold value of the map may be increased or the target lateral acceleration G _YO may be underestimated. The size is high μ
A value lower than 0.25 g in the case of the target drive torque T _OH for road turning control is preferable. This is because even if the vehicle speed V is low and the gear is in the first gear, the road should not be suddenly started because the road is slippery.

Then, based on the target longitudinal acceleration G _XO , the reference drive torque T _B is calculated by the equation (10), or
Alternatively, the adoption ratio of this reference drive torque T _B is determined by obtaining the map. In this case, the weighting coefficient α is larger than the coefficient α for high μ roads, and is set as, for example, α = 0.8, but this reduces the rate of reflection to the driver's request on low μ roads, which increases the risk. This is because the vehicle can be safely and reliably turned on a low μ road. On the other hand, as the driver's required drive torque T _d , the one calculated at the time of the calculation work for the high μ road is adopted as it is. Therefore, the target drive torque considering the required drive torque T _d to the reference drive torque T _B is used. T _OL is calculated by the following equation (12) similar to the above equation (11). T _OL = α · T _B + (1−α) T _d (12) The vehicle 68 is provided with a manual switch (not shown) for the driver to select the turning control for the low μ road. When the person operates the manual switch to select the turning control for the low μ road, the turning control for the low μ road described below is performed.

Target drive torque T for this low μ road turning control
_As shown in FIG. 20 showing the flow of control for determining _OL , the target drive torque T _OL is calculated by the detection and calculation processing of various data in L1 as described above, but this operation is performed manually. It is performed regardless of the switch operation. Next, at L2, it is determined whether the vehicle 68 is in the turning control on the low μ road, that is, whether the low μ road turning control flag F _CL is set. Since the low μ road turning control is not initially performed, it is determined that the low μ road turning control flag F _CL is in the reset state, and the actual lateral acceleration G calculated by the rotation difference between the rear wheels 64 and 65 at L3. target lateral acceleration G _YO is whether greater than a predetermined threshold value by adding 0.05g in _Y, a large value is towards the target lateral acceleration G _Y0 than the actual lateral acceleration G _Y is i.e. a low μ road since, it is determined whether the target lateral acceleration G _Y0 is greater than the threshold value, when the target lateral acceleration G _Y0 is greater than the threshold, the vehicle 68 is determined to be traveling on a low μ road. The actual lateral acceleration G _Y generated in the vehicle 68 is calculated from the peripheral speed difference between the rear wheels 64 and 65 and the vehicle speed V by the following equation (13). _{G Y = | V RL -V RR} | · V / 3.6 2 · b · g ... (13) where, b is the tread of the rear wheels 64 and 65.

When the target lateral acceleration G _YO is larger than the threshold value (G _Y +0.05 g) in the step of L3, that is, when the vehicle 68 is in the turning control on the low μ road, the TCL 58 is incorporated in the TCL 58 at L4. The timer for low μ road (not shown) is counted up, and the count time of the timer for low μ road is, for example, 5 milliseconds. Until the count of the low μ road timer is completed, the process proceeds to the steps after L6 described later, and the target lateral acceleration G _YO according to the equation (9) and the actual lateral acceleration according to the equation (13) are taken every 15 milliseconds. The acceleration G _Y is calculated and the determination operation in the L3 step is repeated. That is, until 0.5 seconds elapses after the low μ road timer starts counting, the process proceeds to L8 through L6 and L7, and the TCL 58 outputs the maximum torque of the engine 11 as the target drive torque T _OL . As a result, the ECU 54 reduces the duty ratio of the torque control solenoid valves 46 and 51 to the 0% side, and as a result, the engine 11 generates a drive torque according to the amount of depression of the accelerator pedal 26 by the driver. When the state where the target lateral acceleration G _YO is larger than the threshold value (G _Y + 0.05g) does not continue for 0.5 seconds, the TCL 58 determines that the vehicle 68 is not traveling on the low μ road, and sets the timer for the low μ road at L9. The count is cleared and the process proceeds to steps L6 to L8.

The target lateral acceleration G _YO is a threshold value (G _Y +0.05 g)
If the larger state continues for 0.5 seconds, it is determined at L10 whether the idle switch 57 is in the off state, and if the idle switch 57 is in the on state, that is, if the accelerator pedal 26 is not depressed by the driver. , The low μ road timer is cleared at L9 without shifting to the low μ road turning control, and the process proceeds to steps L6 to L8 where the TCL 58 sets the maximum torque of the engine 11 as the target drive torque T _OL. As a result, the ECU 54 reduces the duty ratio of the torque control solenoid valves 46, 51 to the 0% side, and as a result, the engine 11 causes the driver to depress the accelerator pedal 26.
The drive torque is generated according to the amount of depression of. This L1
When it is determined in step 0 that the idle switch 57 is off, that is, the accelerator pedal 26 is depressed by the driver, the low μ road turning control flag F _CL is set at L11. Next, at L6, it is determined whether or not the steering angle neutral position learned flag F _H is set, that is, the reliability of the steering angle δ detected by the steering angle sensor 70.

When it is determined in step L6 that the steering angle neutral position learned flag F _H is set, it is determined again in step L7 whether the low μ road turning control flag F _CL is set. . If the low μ road turning control flag F _CL is set in the step L11,
In step 12, the previous calculated value, that is, the target drive torque T _{OL in} step L1 is used as it is. The L
If it is determined in step 6 that the steering angle neutral position learned flag F _H is not set, there is no credibility of the steering angle δ, so the process proceeds to step L8, where L1 was calculated earlier (1
The target drive torque T _OL of the equation (3) is not adopted, and the TCL 58 outputs the maximum torque of the engine 11 as the target drive torque T _OL , whereby the ECU 54 causes the torque control solenoid valve 46,
As a result of reducing the duty ratio of 51 to 0%, the engine 1
1 generates a driving torque according to the amount of depression of the accelerator pedal 26 by the driver.

On the other hand, if it is determined in step L2 that the low μ road turning control flag F _CL is set, the process proceeds to step L13. This L13-L16
In step, as in the case of high μ road turning control, than the difference ΔT between a currently calculated target driving torque T _OL and the target driving torque T _OL previously calculated _(n-1) is increased or decreased tolerance T _K If it is within the increase / decrease allowable amount T _K in any increase or decrease, the target drive torque T _OL calculated this time is used as it is as the calculated value in the step L12, and ΔT is the increase / decrease allowable amount. If it exceeds T _K , the target drive torque T _OL is regulated by the increase / decrease allowable amount T _K. That is, in order to reduce the target drive torque T _OL , L15
Then, the target drive torque T _OL of this time is corrected by the following equation, and this is adopted as the calculated value in the step of L12. _{T OL = T OL (n-} 1) to -T _K Conversely, in the case of increasing the target driving torque T _OL is, L1
In 6, the target drive torque T _OL of this time is corrected by the following equation,
This is adopted as the calculated value in the step of L12. T _OL = T _{OL (n-1)} + T _K

When the target drive torque T _OL is set as described above, the TCL 58 determines in L17 whether this target drive torque T _OL is larger than the driver's required drive torque T _d . Here, when the low μ road turning control flag F _CL is set, the target drive torque T _OL is not larger than the required drive torque T _d , so the routine proceeds to the step of L9, where the low μ road timer counts. To clear L6, L
When it is determined that the steering angle neutral position learned flag F _H is set, and it is further determined that the low μ road turning control flag F _CL is set, the process proceeds to step 7.
The calculated value adopted in the step of L1, L15 or L16 is selected as the drive torque T _OL for the low μ road turning control. In step L17, the target drive torque T
Even if it is determined that _OL is larger than the drive torque _Td requested by the driver, if it is determined in the next L18 that the steering shaft turning angle δ _H is not less than 20 degrees, for example, the vehicle 68 is turning. Since there is, the turning control is continued.

At step L17, the target drive torque T _OL is judged to be larger than the driver's required drive torque T _d , and at L18 the steering shaft turning angle δ _H is judged to be less than 20 degrees, for example. In this case, the TCL 58 resets the low μ road turning control flag F _CL at L19 because it means that the vehicle 68 has finished turning. This L19
When the low μ road turning control flag F _CL is reset in the step, it is not necessary to count the low μ road timer, so the count of the low μ road timer is cleared to L6.
Move to L7 step, but low μ at L7 step
Since it is determined that the road turning control flag F _CL is in the reset state, the process proceeds to step L8, where the TCL 58 outputs the maximum torque of the engine 11 as the target drive torque T _OL ,
As a result, the ECU 54 controls the torque control solenoid valves 46, 51.
As a result of lowering the duty ratio of 0 to the 0% side, the engine 11 generates a drive torque according to the amount of depression of the accelerator pedal 26 by the driver.

In order to simplify the above-described turning control procedure, it is of course possible to ignore the driver's required drive torque T _d , and in this case, the target drive torque is calculated by the above equation (10). It suffices to adopt a possible reference drive torque T _B. Further, even when the driver's required drive torque T _d is taken into consideration as in the present embodiment, the weighting coefficient α is not set to a fixed value, but as shown in FIG. The value of α may be gradually decreased, or may be gradually decreased according to the vehicle speed as shown in FIG. 22, so that the adoption ratio of the driving torque T _d requested by the driver is gradually increased. Similarly, as shown in FIG. 23, the value of the coefficient α is kept constant for a while after the control is started, and is gradually decreased after a lapse of a predetermined time, or the steering shaft turning amount δ _H is increased. It is also possible to increase the value of the coefficient α so that the vehicle 68 can safely travel, especially in a turning circuit in which the radius of curvature becomes gradually smaller.

In the arithmetic processing method described above, the engine 1
To prevent deceleration shock due to fluctuations of 1 abrupt driving torque, target driving torque T _OH, the target driving torque T _OH by decreasing tolerance T _K when calculating the T _OL, T
I am trying to regulate _OL , but this regulation is the target longitudinal acceleration G
It may be done for _XO . When the increase / decrease allowable amount in this case is G _K , the target longitudinal acceleration G at N times
The calculation process of _{XO (n)} is shown below. When G _{XO (n)} −G _{XO (n-1)} > G _K , G _{XO (n)} = G _{XO (n-1)} + G _K G _{XO (n)} −G _{XO (n-1)} <−G _In the case of _K , G _{XO (n)} = G _{XO (n-1)} −G _{K If} the sampling time of the main timer is set to 15 milliseconds and the change in the target longitudinal acceleration G _XO is suppressed to 0.1 g per second, It becomes the following formula. G _K = 0.1 ・ Δt

Target drive torque T for this low μ road turning control
After calculating the _OL , the TCL 58 selects the optimum final target drive torque T _O from these three target drive torques T _OS , T _OH , and T _OL , and outputs this to the ECU 54. In this case, in consideration of the traveling safety of the vehicle 68, the target drive torque having the smallest numerical value is preferentially output. However, in general, since the target drive torque T _OS for slip control is always smaller than the target drive torque T _OL for low μ road turning control, slip control, low μ road turning control, high μ road turning The final target drive torque T _O may be selected in the order for control. As shown in FIG. 24 showing the flow of this processing, after calculating the above-mentioned three target drive torques T _OS , T _OH and T _OL in M11, is the slip control flag F _S set in M12? Determine whether or not. If it is determined in step M12 that the slip control flag F _S is set, the TCL 58 selects the target drive torque T _OS for slip control as the final target drive torque T _O in M13 and sets it. Output to the ECU 54.

The ECU 54 has the engine speed N _E and the engine 1
Throttle opening θ with the driving torque of 1 as a parameter
A map for obtaining _T is stored, and at M14, the ECU 54 uses this map to calculate the current engine speed N _E.
And the target throttle opening θ _TO corresponding to this target drive torque T _OS . Next, the ECU 54 obtains the deviation between the target throttle opening θ _TO and the actual throttle opening θ _T output from the throttle opening sensor 56, and determines the duty ratios of the pair of torque control solenoid valves 46 and 51 as the deviation. The solenoid valves for torque control 46, 5
Apply current to the solenoid of the plungers 47 and 52 of 1
By the operation of the actuator 36, the actual throttle opening θ _T is controlled to fall to the target value θ _TO . M12
If it is determined that the slip control in-progress flag F _S has not been set in the step of step, it is determined in M15 whether the low μ road turning control in-progress flag F _CL is set.

If it is determined in step M15 that the low-μ road turning control flag F _CL is set, the target drive torque T _OL for low-μ road turning control is set as M16 as the final target drive torque T _O. Select with and move to the step of M14. If it is determined in step M15 that the low μ road turning control flag F _CL is not set, M
At 17, it is determined whether the high μ road turning control flag F _CH is set. If it is determined in step M17 that the high μ road turning control flag F _CH is set, the target drive torque T _OH for high μ road turning control is set to M18 as the final target drive torque T _O. Select, M
Go to step 14.

On the other hand, if it is determined in the step M17 that the high μ road turning control flag F _CH is not set, the TCL 58 outputs the maximum torque of the engine 11 as the final target drive torque T _O. As a result, the ECU 54 reduces the duty ratio of the torque control solenoid valves 46 and 51 to the 0% side, and as a result, the engine 11 generates a drive torque according to the amount of depression of the accelerator pedal 26 by the driver. In this case, in this embodiment, a pair of torque control solenoid valves 46,
The ECU 51 does not unconditionally set the duty ratio of 51 to 0%.
4 compares the actual accelerator opening θ _A with the maximum throttle opening regulation value, and if the accelerator opening θ _A exceeds the maximum throttle opening regulation value, the throttle opening θ _A is the maximum throttle opening regulation value. So that the duty ratios of the pair of torque control solenoid valves 46, 51 are determined so that
Drive 7,52. This maximum throttle opening regulation value is a function of the engine speed N _E and is a certain value (for example, 200
0 rpm) or higher, the valve is set to the fully closed state or in the vicinity thereof, but in the low rotation speed range below this, it is set to gradually decrease to an opening of several tens% as the engine speed N _E decreases. I am doing it.

The reason why the throttle opening θ _T is regulated in this way is to enhance the control response when it is determined that the TCL 58 needs to reduce the drive torque of the engine 11. That is, the current design policy of the vehicle 68 is
In order to improve the acceleration performance and the maximum output of the vehicle 68, the bore diameter (passage cross-sectional area) of the throttle body 16 tends to be extremely large, and when the engine 11 is in the low rotation speed region, the throttle opening θ _T The intake air amount becomes saturated at about several tens of percent. Therefore, rather than setting the throttle opening θ _T to fully open or in the vicinity thereof according to the depression amount of the accelerator pedal 26, the throttle opening θ _T is regulated to a predetermined position, so that the target when the drive torque reduction command is issued is set. This is because the deviation between the throttle opening θ _TO and the actual throttle opening θ _T is reduced and the target throttle opening θ _TO can be quickly reduced.

In the above-described embodiment, the target drive torques for two types of turning control, the high μ road and the low μ road, are calculated, but the road surface intermediate between the high μ road and the low μ road is calculated. The corresponding target drive torque for turning control may be calculated, and the final target drive torque may be selected from these target drive torques. Conversely, one type of target drive torque T _OM for turning control is calculated, and when slip control is in progress, this target drive torque T _OS for slip control is generally higher than the target drive torque T _OM for turn control. Is always small,
Of course, it is possible to select the target drive torque T _OS for slip control _prior to the target drive torque T _OM for turn control. As shown in FIG. 25 showing the flow of processing of another embodiment according to the present invention, the target drive torque T _OS for slip control and the target drive torque T _OM for turn control have been described in M21. After calculating in the same way as
At 2, it is determined whether or not the slip control flag F _S is set.

If it is determined in step M22 that the slip control flag F _S is set, the target drive torque T _OS for slip control is selected in M23 as the final target drive torque T _O. Then, at M24, E
The CU 54 sets the target engine throttle opening θ _TO corresponding to the current engine speed N _E and the target drive torque T _OS to the ECU 5
4 is read from the map stored in FIG. 4, the deviation between the target throttle opening θ _TO and the actual throttle opening θ _T output from the throttle opening sensor 56 is calculated, and the deviation between the pair of torque control solenoid valves 46 and 51 is calculated. The duty ratio is set to a value commensurate with the deviation, and a current is passed through the solenoids of the plungers 47, 52 of the torque control solenoid valves 46, 51, and the actual throttle opening θ _T
Is controlled to decrease to the target value θ _TO . If it is determined in step M22 that the slip control flag F _S is not set, the turning control flag F _S is set in M25.
Determine if _M is set. If it is determined in step M25 that the turning control flag F _M is set, the target driving torque T _OM for turning control is selected in M26 as the final target driving torque T _O , and M2 is selected.
Go to step 4.

On the other hand, if it is determined in step M25 that the turning control flag F _M is not set,
The TCL 58 outputs the maximum torque of the engine 11 as the final target drive torque T _O , whereby the ECU 54 reduces the duty ratio of the torque control solenoid valves 46, 51 to the 0% side, and as a result, the engine 11 causes the driver to operate the accelerator pedal. 26
The drive torque is generated according to the amount of depression of. In the above embodiment, when the shift speed is the first speed, the target driving torque is made relatively high to cause insufficient acceleration by lowering the threshold value of the map or estimating the target longitudinal acceleration G _XO low. Although it has been resolved, other means may be used as long as the target drive torque can be made relatively high. Further, the gear stage is not limited to the first gear stage, but may be a low gear stage such as the second gear stage.

[0087]

As described above in detail with reference to the embodiments, according to the vehicle turning control device of the present invention, the greater the magnitude of the lateral acceleration generated when the vehicle turns, the more the target driving torque is increased. Instead of setting it small, the lateral acceleration is relatively large, for example when turning with a small radius,
When the speed is low, the target drive torque is set to be relatively large, so that it is possible to secure safety and enhance the driving feeling. Also, since the target drive torque is set to a relatively large value when the gear is a low speed,
Sufficient acceleration can be obtained even when starting from a T-shaped road. At other gears, the target driving torque is relatively limited by the lateral acceleration, the vehicle speed, etc., so that the vehicle can turn safely.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a control system of an engine of an embodiment of a vehicle turning control device according to the present invention.

FIG. 2 is a conceptual configuration diagram of a control system of an engine of an embodiment of a vehicle turning control device according to the present invention.

FIG. 3 is a cross-sectional view showing a throttle valve drive mechanism of an embodiment of a vehicle turning control device according to the present invention.

FIG. 4 is a flowchart showing an overall flow of control according to an embodiment of a vehicle turning control device according to the present invention.

FIG. 5 is a flowchart showing a flow of a neutral position learning correction control of a steering shaft.

FIG. 6 is a graph showing an example of a correction state of a learned value when the neutral position of the steering shaft is learned and corrected.

FIG. 7 is a graph showing a relationship between a friction coefficient between a tire and a road surface and a slip ratio of this tire.

FIG. 8 is a map showing the relationship between vehicle speed and running resistance.

FIG. 9 is a map showing the relationship between corrected longitudinal acceleration and speed correction amount.

FIG. 10 is a flowchart showing a flow of slip control.

FIG. 11 is a block diagram showing a procedure for calculating a target drive torque for a high μ road.

FIG. 12 is a graph showing the relationship between lateral acceleration and steering angle ratio for explaining the stability factor.

FIG. 13 is a map showing a relationship between a target lateral acceleration, a vehicle speed, and a target longitudinal acceleration.

FIG. 14 is a map showing a relationship between lateral acceleration and road load torque.

FIG. 15 is a map showing the relationship between engine speed, accelerator opening, and required drive torque.

FIG. 16 is a flowchart showing the flow of turning control for a high μ road.

FIG. 17 is a graph showing the relationship between the steering shaft turning angle, the target drive torque, and the longitudinal acceleration.

FIG. 18 is a block diagram showing a procedure for calculating a target drive torque for a low μ road.

FIG. 19 is a map showing the relationship between target longitudinal acceleration, target lateral acceleration, and vehicle speed.

FIG. 20 is a flowchart showing the flow of turning control for a low μ road.

FIG. 21 is a graph showing the relationship between the time after the start of control and the weighting coefficient.

FIG. 22 is a graph showing the relationship between vehicle speed and weighting coefficient.

FIG. 23 is a graph showing the relationship between the time after the start of control and the weighting coefficient.

FIG. 24 is a flowchart showing an example of a final target torque selection operation.

FIG. 25 is a flowchart showing another example of the final target torque selection operation.

[Explanation of symbols]

11 Engine 12 Combustion Chamber 13 Intake Pipe 14 Intake Passage 15 Throttle Valve 17 Throttle Shaft 18 Accelerator Lever 19 Throttle Lever 26 Accelerator Pedal 27 Cable 29 Claw 30 Stopper 36 Actuator 38 Control Rod 42 Connection Piping 43 Vacuum Tank 44 Check Valve 45 Piping 50 Piping 46 Electromagnetic Valve for Torque Control 51 Electromagnetic Valve for Torque Control 54 ECU 55 Crank Angle Sensor 56 Throttle Opening Sensor 57 Idle Switch 58 TCL 59 Accelerator Opening Sensor 60 Front Wheel 61 Front Wheel 62 Front Wheel Rotation Sensor 63 Front Wheel Rotation Sensor 64 Rear Wheel 65 Rear Wheel 66 Rear Wheel Rotation Sensor 67 Rear Wheel Rotation Sensor 68 Vehicle 69 Steering Axis 70 Steering Angle Sensor 71 Communication Cable A Stability Factor F _H Steering Neutral Position Learned Flag F _S Slip Controlling flag F _CH High μ road turning control flag F _CL Low μ road turning control flag FM _M Turning control flag G _X Longitudinal acceleration G _XO Target longitudinal acceleration G _Y Lateral acceleration G _YO Target lateral acceleration g Gravity acceleration T _OS Target drive torque for slip control T _OH Target drive torque for high μ road T _OL Target drive torque for low μ road T _OM Target drive torque for swing control T _O Final target drive torque T _B Reference drive torque T _d Required drive torque V Vehicle speed ΔV Slip amount θ _A Accelerator opening θ _T Throttle opening θ _TO Target throttle opening δ Front wheel steering angle δ _H Steering shaft turning angle δ _C Steering shaft neutral position

Claims (1)

[Claims] 1. A torque control means for reducing a drive torque of an engine independent of a driver's operation, and a target drive torque of the engine set according to a magnitude of lateral acceleration applied to a vehicle during turning. In a vehicle including a turning control unit that controls the operation of the torque control means so that the drive torque of the engine becomes the target drive torque, the target drive torque is lower as the lateral acceleration increases, and A turning control device for a vehicle, wherein the vehicle speed is set to be higher as the vehicle speed becomes lower, and is set to be higher at a low speed shift stage than at other shift stages.