JP3412232B2 - Differential limit torque control device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a differential limiting torque control device for electronically controlling a differential limiting torque applied between right and left driving wheels based on accelerator opening information.

[0002]

2. Description of the Related Art Conventionally, a differential limiting torque control device for electronically controlling a differential limiting torque applied between left and right driving wheels based on accelerator opening information is disclosed in, for example, Japanese Patent Laid-Open No. 2-15.
The one described in Japanese Patent No. 5842 is known.

The above-mentioned conventional sources disclose a control technique for increasing the differential limiting torque as the accelerator opening is increased to ensure a high startability when the vehicle starts on a low μ road.

In this differential limiting torque control sensitive to the accelerator opening, when a control gain, which is a torque increase gradient with respect to the accelerator opening, is given at a constant value, the following problems occur during an acceleration turn.

(1) When the control gain is set to a small value, it is preferable that the yaw is suppressed from being generated due to the accelerator operation during the acceleration turn on the low μ road where the lateral acceleration is low, and the acceleration turn stability is obtained. However, during acceleration turning on a high μ road with high lateral acceleration, the wheel load moves to the outer wheel side, making it easier for the turning inner wheel side to run idle. Transmission is not utilized, the total engine driving force transmitted to the left and right drive wheels is low, and traction performance is poor.

(2) When the control gain is set to a large value, during acceleration turning on a low μ road that results in low lateral acceleration, there is no wheel load movement, and therefore the turning outer wheel, which is on the high speed side due to differential limitation, moves from the turning outer wheel to the low speed side. The engine driving force is transmitted to the turning inner wheel,
Push understeer occurs and the vehicle behavior becomes unstable. However, at the time of acceleration turning on a high μ road, which is a high lateral acceleration, the movement of the engine driving force to the turning outer wheel side due to the differential limitation according to the accelerator operation is utilized to improve the turning limit and the traction performance.

As described above, when the control gain is variably given by the lateral acceleration, it is given as a constant low value in the low lateral acceleration range, and as a constant high value in the high lateral acceleration range, and the intermediate lateral range. In the acceleration range, by giving two values using a control gain characteristic that connects at a predetermined gradient, both lateral stability changes at low lateral acceleration and improvement of traction performance at high lateral acceleration, and lateral acceleration changes. It is possible to prevent sudden changes in vehicle behavior during the transition period.

[0008]

However, in the above case, the control gain is set only by the magnitude of the lateral acceleration. Therefore, even when the same high lateral acceleration occurs, the high lateral speed at high speed running is high. The situation is different when acceleration is generated and when high lateral acceleration is generated due to low or medium speed running, and if high control gain is given as it is when high lateral acceleration occurs at high speed running, the stability of vehicle behavior is impaired for the following reasons. There is.

First, when turning at high lateral acceleration due to high speed running, the gear position is usually high such as 4th speed or 5th speed. That is, the engine driving force input to the differential is small. This means that the left and right drive wheels can be made rigid (directly connected) with a small amount of differential limitation.
Therefore, if the increase gain (control gain) of the differential limiting torque with respect to the accelerator pedal operation is large, the oversteer moment immediately appears and the vehicle behavior fluctuates. However, if a low control gain is used, as in low and medium speed running, high lateral acceleration will occur, which makes the inner wheel side of the wheel more likely to run idle. Cause decline.

Even when the vehicle is turning at the same vehicle speed and lateral acceleration, the stability of the vehicle behavior may be impaired for the following reasons unless the change in the engine torque (= differential input torque) depending on the gear position is considered. .

First, for example, if the control gain is tuned to a small differential limiting torque so as not to induce power oversteer during acceleration cornering in the third speed, the differential limiting torque may be insufficient during the acceleration cornering in the second speed. . On the contrary, if tuning is performed to a control gain of a large differential limiting torque that emphasizes sports running during acceleration cornering in 2nd speed, there is a problem that the amount of oversteer becomes excessive during acceleration cornering in 3rd speed.

The present invention has been made in view of the above problems. A first object of the present invention is to electronically control a differential limiting torque applied between left and right driving wheels based on accelerator opening information. In the dynamic limit torque control device, while preventing a sudden change in vehicle behavior during the transitional period when the lateral acceleration changes,
It is to achieve both improvement of the traction performance at the time of high lateral acceleration turning by medium speed running and improvement of turning stability at the time of high lateral acceleration turning by high speed running.

A second object is that in a differential limiting torque control device for electronically controlling the differential limiting torque applied between the left and right driving wheels based on the accelerator opening information, the shift selected at the time of acceleration turn. Even if there is a difference in the ratio, while achieving almost the same turning performance, both traction performance improvement at high lateral acceleration turning due to low and medium speed running and improvement of turning stability at high lateral acceleration turning due to high speed running are well compatible Is to let.

[0014]

In order to achieve the above-mentioned first object, the differential limiting torque control device of the first aspect of the present invention is as follows.
As shown in the claim correspondence diagram, the differential limiting torque applying means a, which is provided between the left and right driving wheels, applies differential limiting torque according to a control command from the outside, and the accelerator opening degree for detecting the accelerator opening degree. The detecting means b, the lateral acceleration detecting means c for detecting the lateral acceleration applied to the vehicle, the vehicle body speed detecting means d for detecting the vehicle body speed, and the vehicle body speed detection value from the vehicle body speed detecting means d are higher than the medium vehicle body speed. In the vehicle body speed region, the vehicle body speed detection value from the vehicle body speed detecting means d and the lateral acceleration gain setting means e for setting the vehicle body speed sensitive lateral acceleration gain with a value that becomes lower as the vehicle body speed becomes higher and the vehicle body speed detection value from the medium vehicle speed become higher. A control gain maximum value setting means f for setting a control gain maximum value of the vehicle body speed response by a value that becomes lower as the vehicle body speed becomes higher in the vehicle body speed region, and the lateral acceleration detection value from the lateral acceleration detection means c is a medium lateral acceleration. region The higher the lateral acceleration, the higher the gradient due to the lateral acceleration gain, the maximum value of which is the control gain setting means g for setting the lateral acceleration sensitive control gain defined by the control gain maximum value, and the accelerator opening degree detecting means. The accelerator opening sensitive target torque calculating means h for calculating the accelerator opening sensitive target torque with a value that increases at a rate of change determined by the control gain as the detected value of the accelerator opening from b increases, and the accelerator opening sensitive target torque. And an accelerator opening sensitive differential limiting control means i for outputting a control command to obtain the differential limiting torque applying means a.

In order to achieve the above-mentioned second object, in the differential limiting torque control device of the second invention, as shown in the claim correspondence diagram of FIG. A differential limiting torque applying means a for applying a differential limiting torque according to a control command; an accelerator opening detecting means b for detecting an accelerator opening; a lateral acceleration detecting means c for detecting a lateral acceleration applied to a vehicle; A vehicle body speed detecting means d for detecting a vehicle body speed, a gear ratio detecting means j for detecting a gear ratio, and a gear ratio sensitive with a higher value as the gear ratio from the gear ratio detecting means j is a gear ratio with a strong demand for acceleration. And a correction coefficient setting means k for setting the correction coefficient of the vehicle body speed control means for controlling the vehicle body speed sensitivity by a value in which the vehicle body speed detection value from the vehicle body speed detecting means d becomes lower as the vehicle body speed becomes higher in the medium to high vehicle body speed region. Control to set the maximum gain value In-maximum value setting means f, a function of the lateral acceleration detection value from the lateral acceleration detection means c, and a gradient due to the correction coefficient of the gear ratio sensitivity increase, and the maximum value thereof becomes a lateral value defined by the control gain maximum value. Control gain setting means g ′ for setting the control gain of acceleration sensitivity
And an accelerator opening sensitive target torque calculating means h for calculating an accelerator opening sensitive target torque with a value that increases with a change rate determined by the control gain as the accelerator opening detected value from the accelerator opening detecting means b increases. , And an accelerator opening sensitive differential limiting control means i for outputting a control command for obtaining the accelerator opening sensitive target torque to the differential limiting torque applying means a.

[0016]

The operation of the first invention will be described.

When the vehicle is running, the lateral acceleration gain setting means e changes the lateral speed of the vehicle body depending on the value of the vehicle speed detection value from the vehicle speed detecting means d which becomes lower as the vehicle speed becomes higher in the medium to high vehicle speed region. The acceleration gain is set, and in the control gain maximum value setting means f, the vehicle body speed detection value from the vehicle body speed detecting means d becomes lower as the vehicle body speed becomes higher in the medium to high vehicle body speed region. The maximum control gain value is set. Then, in the control gain setting means g, the lateral acceleration detection value from the lateral acceleration detecting means c becomes higher due to the gradient due to the lateral acceleration gain as the lateral acceleration becomes higher in the medium lateral acceleration region, and its maximum value is defined by the maximum control gain value. A control gain for lateral acceleration is set, and a value that increases in the rate of change determined by the control gain as the accelerator opening detection value from the accelerator opening detection means b in the accelerator opening sensitive target torque calculation means h increases. Accelerator opening sensitive target torque is calculated by
In the accelerator opening sensitive differential limiting control means i, a control command for obtaining the accelerator opening sensitive target torque is output to the differential limiting torque applying means a, and differential limiting torque is applied between the left and right driving wheels.

Therefore, when the vehicle is turning at a high lateral acceleration at low and medium vehicle speeds, the maximum lateral acceleration gain and the control gain maximum value for the vehicle body speed sensitivity are set to high values due to the low and medium vehicle speeds. As a result, the lateral acceleration sensitive control gain is set to a higher value by the lateral acceleration gain and the control gain maximum value due to this high value. Therefore, when turning at high lateral acceleration at low and medium vehicle speeds, which is in a low gear position, increasing the accelerator pedal operation amount results in an increase in the differential limiting torque that responds well to the accelerator pedal operation amount, resulting in idling turning. Engine driving force is transmitted from the inner wheel side to the turning outer wheel side, and traction performance is improved.

Further, when the vehicle is turning at a high lateral acceleration at a high vehicle speed, the maximum lateral acceleration gain and the control gain maximum value, which are sensitive to the vehicle speed, are set to a low value due to the high vehicle speed. Regardless, the lateral acceleration sensitive control gain is set to a lower value by the lateral acceleration gain due to this low value and the control gain maximum value. Therefore, when turning the vehicle at a high lateral acceleration with a high gear position and high lateral acceleration, increasing the accelerator pedal operation amount causes a gradual increase in the differential torque limit with respect to the accelerator pedal operation amount, causing the differential torque limit to rise rapidly. The occurrence of oversteer moment due to is suppressed, and the stability of vehicle behavior is secured.

Further, when the lateral acceleration fluctuates due to the change of the vehicle speed or the turning radius during turning, the control gain is given by a value which changes with the gradient due to the lateral acceleration gain, and the accelerator opening sensitive target using this control gain. Since the torque changes smoothly, it is possible to prevent the vehicle behavior from becoming unstable due to the abrupt change of the differential limiting torque when the lateral acceleration changes.

The operation of the second invention will be described.

Operationally different from the first aspect of the present invention, in setting the correction coefficient, in the correction coefficient setting means k, the gear ratio from the gear ratio detecting means j has a higher value as the gear ratio has a stronger acceleration request. A correction coefficient for gear ratio sensitivity is set by the control gain setting means g ', and in setting the control gain, the control gain setting means g'is a function of the lateral acceleration detection value from the lateral acceleration detecting means c and the gradient of the gear ratio sensitivity correction coefficient. The control gain for the lateral acceleration response is set so that the maximum value becomes higher.

Therefore, similarly to the first aspect of the invention, the traction performance is improved when the vehicle is turning at a high lateral acceleration at low and medium vehicle speeds, and the oversteer moment is suppressed when the vehicle is turning at a high lateral acceleration at a high vehicle speed. The stability of vehicle behavior is ensured.

In addition, the gear ratio is set to a correction coefficient for gear ratio sensitivity that is higher as the gear ratio has a higher acceleration demand, so that the gear shift set at the time of acceleration cornering due to the same lateral acceleration at the same vehicle speed. Even if the ratio (gear position, etc.) is different, the differential limiting torque is applied by the control gain according to the difference in the gear ratio, and the differential limiting torque is applied by the same control gain regardless of the gear ratio. Insufficient control differential limiting torque and excessive oversteering as in the case of application are not caused, and almost the same turning performance can be obtained regardless of the difference in gear ratio.

[0025]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) First, the structure will be described.

FIG. 2 is an overall system diagram of a rear wheel drive vehicle to which the differential limiting torque control device of the first embodiment corresponding to the first aspect of the present invention is applied.

In FIG. 2, 1 is an engine, 2 is a transmission, 3 is a propeller shaft, 4 is an electronically controlled limited slip differential (hereinafter abbreviated as electronically controlled LSD), 5 and 6 are rear wheels, and 7 and 8 are front wheels. Is.

The electronically controlled LSD 4 has a built-in differential limiting clutch 10 for generating a differential limiting torque between the left and right rear wheels 5 and 6 according to the clutch control pressure applied from the hydraulic unit 9.

The hydraulic unit 9 includes a hydraulic power source 11 and an LS.
And a D control valve 12. The hydraulic unit 9 and the differential limiting clutch 10 correspond to the differential limiting torque applying means a.

The LSD control valve 12 is controlled by the control current ILSD from the active LSD controller 13 to generate a clutch control pressure for the limited differential clutch 10.

In the active LSD controller 13, the left front wheel rotation speed NFL from the left front wheel rotation sensor 14 and
The right front wheel rotation speed NFR from the right front wheel rotation sensor 15, the left rear wheel rotation speed NRL from the left rear wheel rotation sensor 16, the right rear wheel rotation speed NRR from the right rear wheel rotation sensor 17, and the lateral acceleration sensor 18 Lateral acceleration Y from (corresponding to lateral acceleration detecting means c)
G and the longitudinal acceleration XG from the longitudinal acceleration sensor 19,
An accelerator opening ACC from an accelerator opening sensor 20 (corresponding to the accelerator opening detecting means b) and a brake switch 21.
The switch signal BS from the ABS controller 22 and the ABS in-operation flag AS from the ABS controller 22 are input.

Next, the operation will be described.

[Differential Limiting Torque Control Operation Processing] FIG. 3 is a flowchart showing the flow of the differential limiting torque control operation processing performed by the active LSD controller 13 in a control cycle of 10 msec. Each step will be described below.

In step 30, the left front wheel rotation speed NFL, the right front wheel rotation speed NFR, the left rear wheel rotation speed NRL, and the right rear wheel rotation speed NRR.
And lateral acceleration YG and accelerator opening ACC are read.

In step 31, each wheel rotation speed NFL, N
FR, NRL, and NRR are left front wheel speed VFL and right front wheel speed VF, respectively.
R, left drive wheel speed VRL, and right drive wheel speed VRR. The smaller one of the left front wheel speed VFL and the right front wheel speed VFR is set as the vehicle body speed VFF (corresponding to the vehicle body speed detecting means d).

At step 32, the lateral acceleration gain Ka 'is calculated according to the magnitude of the vehicle body speed VFF (corresponding to the lateral acceleration gain setting means e).

As shown in FIG. 4, the lateral acceleration gain Ka 'is set to the set vehicle speeds VAM1, VAM2, VAM3 (VAM1 <VAM2 <VA
M3) divides the vehicle speed range into four and gives it with a constant value of Ka '= KAD1 in the region of VFF ≤ VAM1, and gives it with a value that reduces Ka' from KAD1 to KAD2 in the region of VAM1 <VFF ≤ VAM2, and VAM2 <
In the region of VFF ≦ VAM3, Ka ′ is given as a value decreasing from KAD2 to KAD3, and in the region of VFF> VAM3, Ka ′ = KAD3 is given as a constant value. Here, the set vehicle speed VAM1, VAM2, VAM3 and each gain value KAD1, KAD2, KAD3 are tuning constants,
The optimum value is set according to the vehicle type, control target, and the like.

In step 33, the control gain maximum value Kamax is calculated according to the magnitude of the vehicle body speed VFF (corresponding to the control gain maximum value setting means f).

This control gain maximum value Kamax is, as shown in FIG. 5, set vehicle speeds VAM1, VAM2, VAM3 (VAM1 <VAM2
<VAM3) divides the vehicle speed range into four, and in the region of VFF ≤ VAM1, gives a constant value of Kamax = KAM1, VAM1 <VFF ≤ VAM2
In the region of, Kamax is given as a value that decreases from KAM1 to KAM2, and in the region of VAM2 <VFF ≤ VAM3, Kamax is changed from KAM2 to KA.
It is given to M3 with a decreasing value, and Kamax in the region of VFF> VAM3
= Give a constant value of KAM3. Here, set vehicle speed VAM1, VA
M2, VAM3 and maximum gain values KAM1, KAM2, KAM3 are tuning constants, and optimal values are set according to the vehicle type, control target, and the like.

In step 34, the lateral acceleration YG, the lateral acceleration gain Ka 'obtained in step 32, and step 3
The control gain Ka is calculated by the control gain maximum value Kamax obtained in 3 (corresponding to the control gain setting means g).

This control gain Ka is given by the calculation by the following calculation formula (characteristic shown in FIG. 6).

Ka = min [max {Ka '× (YG-
Y1), Kamin}, Kamax] Here, the lateral acceleration offset value Y1 and the control gain minimum value Kamin are tuning constants, and optimal values are set according to the vehicle type, control target, and the like.

In step 35, the accelerator opening sensitive target torque TA is calculated from the accelerator opening ACC and the control gain Ka obtained in step 34 (corresponding to accelerator opening sensitive target torque calculating means h).

This accelerator opening sensitive target torque TA is
It is given by a calculation using the following calculation formula (characteristics shown in FIG. 7).

TA = min [max {Ka × (ACC-A
0), 0}, TAmax] Here, the accelerator opening offset value A0 and the accelerator opening sensitive maximum torque TAmax are tuning constants, and optimal values are set according to the vehicle type, control target, and the like.

In step 36, a control command for obtaining the accelerator opening sensitive target torque TA is output (corresponding to the accelerator opening sensitive differential limiting control means i).

[Aim of Accelerator Opening Sensitive Control] The aim of performing accelerator opening sensitive control that gives the accelerator opening sensitive target torque TA according to the accelerator opening ACC is as follows.

(1) Prevention of understeer in the initial stage of turning This is achieved by reducing the differential limiting torque before the accelerator pedal is depressed.

(2) Improvement of accelerator controllability This is achieved by the control in which the differential limiting amount is increased according to the accelerator opening by the control gain according to the lateral acceleration which is the turning information.

(3) Improvement of acceleration This is achieved by suppressing the drive slip by increasing the differential limiting amount according to the accelerator depression amount.

(4) Both improvement of traction performance at high lateral acceleration turning by low and medium speed running and improvement of turning stability at high lateral acceleration turning by high speed running are both described in detail below. This is achieved by setting the lateral acceleration gain Ka 'and the control gain maximum value Kamax according to the magnitude of the vehicle body speed VFF.

[During high lateral acceleration turning at low and medium speeds]
4 and 5 when turning at high lateral acceleration at low and medium speeds.
As is clear from the characteristics of, the lateral acceleration gain Ka 'and the control gain maximum value Kamax of the vehicle body speed sensitivity are set to high values, and at the time of high lateral acceleration, the lateral acceleration sensitivity control gain Ka is high. The lateral acceleration gain Ka 'and the control gain maximum value Kamax are set to high values according to the characteristics of FIG.

Therefore, when the accelerator pedal operation amount is increased when the vehicle is turning at a high lateral acceleration at low and medium vehicle speeds in a low gear position, as shown in FIG. 7, a large control gain Ka with respect to the accelerator pedal operation amount results. The responsive differential limit torque is increased, and the engine driving force is transmitted from the turning inner wheel side, which tends to slip, to the turning outer wheel side, and traction performance is improved.

[During High Lateral Acceleration Turning at High Speed Running] At the time of high lateral acceleration turning at high speed running, as is apparent from the characteristics of FIGS. Even though the value Kamax is set to a low value and the lateral acceleration is high, the lateral acceleration sensitive control gain Ka is set to a lower value by the lateral acceleration gain Ka ′ and the control gain maximum value Kamax. .

Therefore, even when the accelerator pedal operation amount is increased during high lateral acceleration turning at a high vehicle speed, which is a high gear position such as the fourth gear or the fifth gear position, as shown in FIG. The small control gain Ka causes a gradual increase in the differential limiting torque, which suppresses the occurrence of an oversteer moment due to the sudden increase in the differential limiting torque, and ensures the stability of the vehicle behavior.

[When lateral acceleration changes] When the lateral acceleration fluctuates due to a change in vehicle speed or a turning radius during turning, the control gain Ka is as shown in FIG.
This control gain K is given by the value that changes with the gradient
Since the accelerator opening-sensitive target torque TA using a changes smoothly, it is possible to prevent the vehicle behavior from becoming unstable due to a sudden change in the differential limiting torque when the lateral acceleration changes.

Next, the effect will be described.

(1) To obtain the accelerator opening sensitive target torque TA in the differential limiting torque control device which electronically controls the differential limiting torque applied between the left and right rear wheels 5 and 6 based on the accelerator opening information. The setting of the control gain Ka for the accelerator opening ACC is increased as the lateral acceleration YG increases. However, in the high lateral acceleration range, the control gain Ka is suppressed to be smaller as the vehicle speed VFF is higher, and the differential limiting torque control sensitive to the accelerator opening is controlled. Since it is a device that prevents the sudden change of the vehicle behavior during the transitional period when the lateral acceleration changes, it improves the traction performance at the time of high lateral acceleration turning at low and medium speed running and the turning at the time of high lateral acceleration turning at high speed running. It is possible to achieve both good stability and good stability.

(2) The control gain Ka for the accelerator opening ACC for obtaining the accelerator opening sensitive target torque TA is set in the low lateral acceleration region where the lateral acceleration YG is low regardless of the vehicle speed. Since the device is configured to perform the differential limiting torque control sensitive to the accelerator opening degree while suppressing it to a small value, the yaw generation can be suppressed to a small value when turning on a low μ road, and the turning stability can be secured.

(Second Embodiment) First, the structure will be described.

FIG. 8 is an overall system diagram of a rear wheel drive vehicle to which the differential limiting torque control device of the second embodiment corresponding to the second aspect of the present invention is applied.

In FIG. 8, a structural difference from FIG. 2 is that the gear position GP from the AT controller 23 (corresponding to the gear ratio detecting means j) is added as information input to the active LSD controller 13. Points,
The other structure is similar to that of FIG.

Next, the operation will be described with reference to FIG. 9, which is a flow chart showing the flow of the differential limiting torque control operation processing performed by the active LSD controller 13 at a control cycle of 10 msec. Each step will be described below.

Step 41, step 43, step 4
In step 5 and step 46, the same processing as step 31, step 33, step 35 and step 36 corresponding to FIG. 3 is performed.

In step 40 ', the gear position GP is added to the input information read in step 30.

In step 42 ', the correction coefficient C is determined by the gear position GP (corresponding to the correction coefficient setting means k).

The correction coefficient C is, for example, 1 when the gear position is 1.
C = 1/2 when the gear position is 2nd speed, C = 1 when the gear position is 2nd gear, C = 3/4 when the gear position is 3rd gear, C = 1/4 when the gear position is 4th gear, and 5 gear positions When the vehicle is in the high speed, C = 1/5, the acceleration request is the largest value in the second speed, which is the strongest in the acceleration turn, and thereafter, the third value, the first speed, the fourth speed, and the fifth speed are the smaller values in this order. There is.

In step 44a, the lateral acceleration gain K
a ′ is calculated by the equation Ka ′ = C · YG ² by a quadratic function with respect to the correction coefficient C and the lateral acceleration YG.

In step 44b, the lateral acceleration gain K
It is determined whether or not a'is smaller than the control gain maximum value Kamax, and in step 44c, the lateral acceleration gain Ka '.
Is larger than the control gain minimum value Kamin.

Then, when Ka'≥Kamax, the routine proceeds to step 44d, where the maximum control gain value Kamax is made the control gain Ka, and when Ka'≤Kamin, step 44d.
e, and the control gain minimum value Kamin becomes the control gain Ka.
When Kamin <Ka '<Kamax, the routine proceeds to step 44f, where the lateral acceleration gain Ka' is set to the control gain Ka.
(Corresponding to the control gain setting means g ').

[Setting of Control Gain] In setting the control gain Ka, the correction coefficient C is determined by the gear position GP in step 42 ', and the lateral acceleration gain Ka' is Ka '= C.YG ² in step 44a. The vehicle body speed V is calculated by the equation and by the processing of step 44b to step 44f.
Control gain maximum value Kamax determined by the size of FF
And the control gain minimum value Kamin which is a value that makes the stability and driving performance compatible on the low μ road compatible with each other, and the control gain Ka is set.

Therefore, the control gain Ka is given by the value of the quadratic function of the lateral acceleration YG as shown in FIG. 10. However, depending on the magnitude of the correction coefficient C, for a certain constant lateral acceleration YGO, The gear position has the largest value at the second speed, and then has the smaller value in the order of the third speed, the first speed, the fourth speed, and the fifth speed.

[During Acceleration Turning by Constant Lateral Acceleration with Different Gear Positions] During acceleration cornering by a certain constant lateral acceleration YGO, when the gear position GP at that time is the second speed, as shown by the solid line characteristics in FIG. As the accelerator pedal depression amount is increased, the differential limiting torque increases due to a large increase in the control gain Ka (2) with respect to the accelerator pedal depression amount. On the other hand, when the gear position GP is the second speed, the engine torque input to the rear differential also increases, and the differential limiting effect cannot be obtained unless the differential limiting amount is increased.

That is, in the case of the second speed in which the differential input torque becomes large, the control gain Ka is increased according to the input torque to drive the engine from the turning inner wheel side to the turning outer wheel side, which tends to idle due to the differential limiting effect. Force is transmitted, and vehicle behavior does not fluctuate due to insufficient differential limiting amount as in the case where the control gain is set low,
The turning limit and traction performance are improved.

During acceleration cornering with a certain lateral acceleration YGO, when the gear position GP at that time is the third speed,
As shown by the alternate long and short dash line characteristic in FIG. 11, when the accelerator depression amount is increased, the differential limiting torque gradually rises due to the increase change of the control gain Ka (3) which is small with respect to the accelerator depression amount. On the other hand, when the gear position GP is the third speed, the engine torque input to the rear differential becomes smaller than that in the second speed, and when the differential limit amount is increased, the left and right rear wheels 5, 6 are in a rigid (directly connected) state. It is easy to become.

That is, in the case of the third speed where the differential input torque is smaller than the case of the second speed, the control gain Ka is lowered according to the input torque, so that the turning from the turning inner wheel side, which tends to slip due to the differential limiting effect, occurs. The engine driving force is transmitted to the outer wheel side, power oversteer is not induced due to an excessive differential limiting amount as in the case where the control gain is set low, and the turning limit and the traction performance are improved.

Next, the effect will be described.

In addition to the effect (1) of the first embodiment, the following effect can be obtained.

(3) In setting the control gain Ka, a gear ratio GP correction coefficient C with a higher value is set for a gear position GP with a stronger acceleration request, and Ka '= C. Lateral acceleration gain Ka 'in the formula of YG ²
Since it is a device for performing differential limiting torque control that is sensitive to accelerator opening, it is possible to obtain almost the same turning performance with respect to turning limit and traction performance even if there is a difference in the gear position GP selected during acceleration turning. You can

(4) In the calculation of the lateral acceleration gain Ka ', since the lateral acceleration YG of Ka' = CYG ² is given by the expression increasing with a quadratic function, the control gain for the accelerator depression operation is given. The response to increase in Ka is good, and it is possible to improve the turning limit and the traction performance that reflect the driver's intention to accelerate.

Although the embodiments have been described above with reference to the drawings, the specific structure is not limited to the embodiments, and modifications and additions within the scope of the present invention are included in the present invention. Be done.

For example, in the embodiment, the example in which the differential limiting torque is applied by the hydraulic multi-plate clutch is shown, but if the differential limiting torque can be variably controlled by a control command from the outside, the electromagnetic clutch. And so on.

In the embodiment, an example of a vehicle equipped with an automatic transmission is shown, but the present invention can be applied to a vehicle equipped with a manual transmission in which the gear position is checked by a signal from a shift position switch, and further, a continuously variable transmission. It can be applied by inputting the gear ratio information that is also set in the mounted vehicle.

[0085]

According to the first invention of claim 1,
In a differential limiting torque control device that electronically controls the differential limiting torque applied between the left and right driving wheels based on accelerator opening information, in a high vehicle speed region, the lateral velocity of the vehicle body speed response is reduced by a value that decreases as the vehicle body speed increases. A control gain setting means for setting a control gain for lateral acceleration sensitivity using the acceleration gain and the maximum value of the control gain is provided, and the larger the accelerator opening detection value from the accelerator opening detection means, the greater the rate of change determined by this control gain. The accelerator opening sensitive target torque is calculated according to the value of, and a device provided with an accelerator opening sensitive differential limiting control means for outputting a control command for obtaining this accelerator opening sensitive target torque to the differential limiting torque applying means, While preventing a sudden change in vehicle behavior during the transitional period when the lateral acceleration changes, improve the traction performance and the high Travel effect is obtained that the increase of the turning stability during high lateral acceleration turning can be successfully balance due.

According to the second aspect of the present invention, in the differential limiting torque control device for electronically controlling the differential limiting torque applied between the left and right driving wheels based on the accelerator opening information, lateral acceleration detection is performed. As the gear ratio of the function and acceleration demand is stronger, the gradient becomes higher due to the correction coefficient of the gear ratio sensitivity due to the higher value, and the maximum value becomes the control gain for lateral acceleration that is defined by the maximum value. A control gain setting means for setting is provided, and as the detected value of the accelerator opening from the accelerator opening detection means is larger, the accelerator opening sensitive target torque is calculated by a value that increases at a rate of change determined by this control gain. Since the device provided with the accelerator opening sensitive differential limiting control means for outputting the control command to obtain the sensitive target torque to the differential limiting torque applying means, the acceleration rotation Approximately the same turning performance is obtained even with the selected gear ratio, while improving traction performance during high lateral acceleration turning at low and medium speeds and turning stability during high lateral acceleration turning at high speeds. It is possible to obtain the effect that both the improvement and

[Brief description of drawings]

FIG. 1 is a claim correspondence diagram showing a differential limiting torque control device of the present invention.

FIG. 2 is an overall system diagram of a rear-wheel drive vehicle to which the differential limiting torque control device of the first embodiment is applied.

FIG. 3 is a flowchart showing a flow of differential limiting torque control operation processing performed by the active LSD controller of the first embodiment device.

FIG. 4 is a lateral acceleration gain characteristic diagram with respect to a vehicle speed in the first embodiment device.

FIG. 5 is a control gain maximum value characteristic diagram with respect to a vehicle speed in the first embodiment device.

FIG. 6 is a control gain characteristic diagram with respect to lateral acceleration in the first embodiment device.

FIG. 7 is a characteristic diagram of accelerator opening sensitive target torque with respect to accelerator opening in the first embodiment device.

FIG. 8 is an overall system diagram of a rear-wheel drive vehicle to which the differential limiting torque control device of the second embodiment is applied.

FIG. 9 is a flowchart showing a flow of differential limiting torque control operation processing performed by the active LSD controller of the second embodiment device.

FIG. 10 is a control gain characteristic diagram according to lateral acceleration and gear position in the second embodiment device.

FIG. 11 is a characteristic graph of accelerator opening sensitive target torque with respect to accelerator opening in the second embodiment device.

[Explanation of symbols]

a Differential limiting torque applying means b Accelerator opening detection means c Lateral acceleration detection means d Vehicle speed detection means e Lateral acceleration gain setting means f Control gain maximum value setting means g Control gain setting means h Accelerator position sensitive target torque calculation means i Accelerator position sensitive differential limit control means j Gear ratio detecting means k correction coefficient setting means

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Claims (2)

(57) [Claims] 1. A differential limiting torque applying means provided between left and right driving wheels for applying a differential limiting torque according to a control command from the outside, an accelerator opening detecting means for detecting an accelerator opening, and a vehicle. Lateral acceleration detecting means for detecting lateral acceleration applied to the vehicle body, vehicle body speed detecting means for detecting vehicle body speed, and the vehicle body speed detection value from the vehicle body speed detecting means becomes higher as the vehicle body speed becomes higher in the medium to high vehicle body speed region. Lateral acceleration gain setting means for setting a lateral acceleration gain for sensing a vehicle speed depending on a lower value, and a vehicle body speed detection value from the vehicle body speed detecting means becomes lower as the vehicle body speed becomes higher in a medium to high vehicle body speed region. A control gain maximum value setting means for setting a control gain maximum value of the vehicle body speed response according to the following value, and the lateral acceleration detected by the lateral acceleration detection means increases the lateral acceleration in a medium lateral acceleration region. A control gain setting unit that sets a control gain for a lateral acceleration response, the maximum value of which is increased by a gradient due to a speed gain and the maximum value of which is defined by the control gain maximum value, and an accelerator opening detection value from the accelerator opening detection unit is An accelerator opening sensitive target torque calculating means for calculating an accelerator opening sensitive target torque with a value that increases at a rate of change determined by the control gain, and a control command for obtaining the accelerator opening sensitive target torque are the differential limiting torques. A differential limiting torque control device, comprising: an accelerator opening sensitive differential limiting control means for outputting to an applying means. 2. A differential limiting torque applying means which is provided between the left and right driving wheels and which applies a differential limiting torque according to a control command from the outside, an accelerator opening detecting means which detects an accelerator opening, and a vehicle. Lateral acceleration detecting means for detecting a lateral acceleration applied to the vehicle, vehicle body speed detecting means for detecting a vehicle body speed, gear ratio detecting means for detecting a gear ratio, and a gear ratio from the gear ratio detecting means that has a strong demand for acceleration. A correction coefficient setting means for setting a correction coefficient for gear ratio sensitivity with a higher value as the ratio increases, and the vehicle speed detection value from the vehicle speed detection means decreases as the vehicle speed increases in the medium to high vehicle speed range. A control gain maximum value setting means for setting a control gain maximum value of the vehicle body speed sensitivity according to the following value, a function for the lateral acceleration detection value from the lateral acceleration detection means, and a gradient by the correction coefficient of the gear ratio sensitivity. The control gain setting means for setting the control gain of the lateral acceleration sensitivity whose maximum value is defined by the control gain maximum value, and the greater the accelerator opening detection value from the accelerator opening detection means, the more the control gain An accelerator opening sensitive target torque calculating means for calculating an accelerator opening sensitive target torque with a value that increases at a determined change rate, and an accelerator for outputting a control command for obtaining the accelerator opening sensitive target torque to the differential limiting torque applying means. A differential limiting torque control device comprising: an opening-sensitive differential limiting control means;