JP5640581B2 - Control device for differential limiting mechanism - Google Patents

Description

  The present invention relates to a control device for a differential limiting mechanism of a vehicle.

Some vehicles (automobiles) are equipped with a differential mechanism (LSD: Limited Slip Differential) that limits the differential to a differential mechanism (Differential) that allows the differential of the left and right wheels. Then, by LSD, it is possible to prevent idling when one of the left and right wheels becomes unloaded, and to transmit the driving force to the other wheel.
There are three types of such LSDs: torque sensitive, rotational sensitive, and electronically controlled. In the torque sensitive type, the LSD operates according to the torque from the engine, and in the rotation sensitive type, the LSD operates according to the difference in rotational speed between the left and right wheels. The electronic control type can operate the LSD at an arbitrary timing by an LSD controller.

In any LSD, the driving force is moved from the fastest to the slowest of the left and right wheels by frictional forces such as clutches, gears, oil, etc., so that the wheels are idling (a significant difference between the left and right rotational speeds). It can be suppressed, and acceleration of bad roads can be expected.
Further, in the operation of the LSD in a state where the wheels are not idling, the driving force moves from the turning outer wheel having a high rotation speed to the turning inner wheel having a low rotation speed, that is, the driving force moves in a direction to suppress turning. Therefore, improvement in straight running stability can be expected.

  However, in a vehicle having an LSD on the front differential, torque steer is generated due to the difference in driving force between the left and right wheels due to the operation of the LSD, and the steering torque felt by the driver changes. For example, when the driving force moves from the turning outer wheel to the turning inner wheel by the operation of the LSD (when the turning outer wheel idles), the steering torque increases and the steering operation becomes heavy. Further, when the driving force is moved from the turning inner wheel to the turning outer wheel by the operation of the LSD (when the turning inner wheel is idle), the steering torque is reduced and the steering operation is lightened. Therefore, in a vehicle equipped with an LSD at the front differential, the steering operation becomes heavy or light due to the operation of the LSD, so that there is a problem that the maneuverability deteriorates.

  In this regard, Patent Document 1 focuses on such a problem, and in a vehicle having an LSD in the front differential, an increase in steering steering force when the LSD is activated during a turn traveling, a split road traveling, etc. A technique has been proposed in which the driver appropriately suppresses the noise and eliminates the uncomfortable feeling during the steering operation of the driver. In this technology, means for detecting the operation of the LSD, means for detecting the ground contact state of the left and right front wheels of the vehicle, and control means for controlling the steering assist force based on the detection results from both detection means. The control means, when detecting that the front wheel on the inside of the turn once idles during the operation of the LSD and then comes into contact with the road surface again, sets the steering assist force to be larger than that before the contact.

Japanese Patent No. 3401336

As described above, when the LSD is operated when there is a difference in rotational speed between the left and right wheels, the driving force moves from the side of the wheel that was rotating at a high speed to the side of the wheel that was rotating at a low speed. Since torque steer due to a force difference occurs, a steering reaction force change occurs due to this, and the steering torque becomes uncomfortable.
In particular, when the LSD is strongly operated during idling of the turning inner wheel, the torque of the turning outer wheel is increased and torque steer in the turning direction is generated. Therefore, the steering torque required for the driver is greatly reduced. Rather, the driver is required to have a steering torque opposite to the turning direction. That is, the driver must generate a steering torque in a direction to suppress the steering wheel that turns freely in the turning direction, and the driver feels uncomfortable. For this reason, in the electronically controlled LSD that can arbitrarily control the amount of operation of the LSD, the control amount of the electronically controlled LSD cannot be increased in order to prevent deterioration in steering performance.

Although it is conceivable to suppress this by the technique of Patent Document 1, in order to cope with a large change in the steering reaction force generated by strongly operating the LSD, a high output capable of accurately adding a large steering assist force. A steering assist device is required. For this reason, it is considered difficult to suppress the change in the steering reaction force using only the steering assist device of Patent Document 1.
The present invention was devised from the viewpoint of control of an electronically controlled LSD in view of such problems, and it is required that the LSD operation required and the steering discomfort caused by the change in the steering reaction force caused by the operation of the LSD. An object of the present invention is to provide a control device for a differential limiting mechanism that can balance suppression.

In order to achieve the above object, a control device for a differential limiting mechanism according to the present invention includes a differential limiting mechanism that limits the differential between the left and right wheels of a vehicle, and a control unit that controls the differential limiting mechanism. in includes a steering angle detection means for detecting a steering angle of the vehicle that the driver inputs a steering torque detecting means for detecting a steering torque of the vehicle driver to input, wherein the control means, prior Symbol steering When the direction of the steering angle detected by the angle detection means is different from the direction of the steering torque detected by the steering torque detection means, the control amount (differential limit amount) of the differential limiting mechanism is reduced. It is a feature.

The control device of another differential limiting mechanism of the present invention, in a vehicle having a differential limiting mechanism for limiting a differential between the left and right wheels of the vehicle, and control means for controlling the differential limiting mechanism, driver There has a steering angular velocity detecting means for detecting a steering angular velocity of the vehicle to enter, the steering torque detection means for detecting a steering torque of the vehicle driver to input, wherein the control means, prior Symbol steering angular velocity detecting means When the direction of the steering angular velocity detected by the difference between the direction of the steering angular velocity detected by the steering torque detector and the direction of the steering torque detected by the steering torque detecting means is reduced, the control amount (differential limit amount) of the differential limiting mechanism is reduced. .

In addition, it is preferable that a dead zone region where the control amount (driving force difference) is not reduced is provided in a neutral region of the steering angle or a region near zero of the steering angular velocity.
And a braking force adjusting mechanism for making a difference in the braking force of each wheel of the vehicle, and each wheel idling detecting means for detecting idling of each wheel of the vehicle, wherein the control means includes the differential restriction. When the control amount of the mechanism is reduced, if each wheel idling detection means detects idling of any wheel of the vehicle, it is preferable to apply a braking force to the idling wheel by the braking force adjusting mechanism.

  Further, it is preferable that when the braking force is applied to the idling wheel by the braking force adjusting mechanism, the control means adds a braking force having a magnitude corresponding to the idling state of the idling wheel.

According to the control device for the first differential limiting mechanism of the present invention, the control means differs in the direction of the steering angle detected by the steering angle detection means and the direction of the steering torque detected by the steering torque detection means. At this time, the control amount (differential limit amount) of the differential limiting mechanism is decreased. For this reason, the discrepancy between the direction of the steering angle and the direction of the steering torque caused by the operation of the differential limiting mechanism can be suppressed. For example, when the turning inner wheel is idled and the differential limiting mechanism is activated during steady turning, the driving torque of the turning outer wheel is increased, and torque steer is generated in a direction that encourages turning of the vehicle. At this time, the driver needs to generate a steering torque in the direction opposite to the turning direction in order to keep the steering wheel. On the other hand, by reducing the control amount of the differential limiting mechanism, the discrepancy between the direction of the steering angle and the direction of the steering torque input by the driver can be suppressed, and the steering feeling can be maintained well.

According to another control device for a differential limiting mechanism of the present invention, the control means differs in the direction of the steering angular velocity detected by the steering angular velocity detection means and the direction of the steering torque detected by the steering torque detection means. The control amount of the differential limiting mechanism (differential limiting amount) is reduced. For this reason, the discrepancy between the direction of the steering angular velocity and the direction of the steering torque caused by the operation of the differential limiting mechanism can be suppressed. For example, when the differential limiting mechanism operates during slalom traveling and the direction of the steering angular velocity is different from the direction of the steering torque input by the driver, the occurrence of torque steer is suppressed by limiting the operation of the differential limiting mechanism, Steering feeling can be maintained well.

In addition, since there is a dead zone area where the control amount (driving force difference) is not reduced in the neutral area of the steering angle or the area near zero of the steering angular velocity, it has a neutral steering feeling or a steering angle holding feeling. Can be made. Moreover, the stability of control can be improved.
Further, when the control means detects the idling of one of the wheels of the vehicle when the control amount of the differential limiting mechanism is reduced, the control means adds a braking force to the idling wheel by the braking force adjusting mechanism. The shortage of dynamic restrictions can be compensated.

  In addition, by adding a braking force having a magnitude corresponding to the idling state of the idling wheel, the rotation of the idling wheel can be controlled appropriately.

It is a block diagram of the drive system of the vehicle concerning 1st Embodiment of this invention. It is a figure explaining the restriction | limiting control area | region of the differential restriction | limiting mechanism which made the steering angle (theta) and steering torque (tau) concerning 1st Embodiment of this invention a parameter. It is a control block diagram of the control apparatus of the differential limiting mechanism concerning 1st Embodiment of this invention. It is a flowchart explaining control by the control apparatus of the differential limiting mechanism concerning 1st Embodiment of this invention. It is a figure explaining the restriction | limiting control area | region of the differential restriction | limiting mechanism which made the steering angular velocity d (theta) and steering torque (tau) concerning 2nd Embodiment of this invention a parameter. It is a control block diagram of the control apparatus of the differential limiting mechanism concerning 2nd Embodiment of this invention. It is a flowchart explaining control by the control apparatus of the differential limiting mechanism concerning 2nd Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
<First Embodiment>
1 to 4 show a control device for a differential limiting mechanism according to a first embodiment of the present invention. FIG. 1 is a configuration diagram of a drive system of the vehicle, and FIG. 2 is a limitation of the differential limiting mechanism. FIG. 3 is a control block diagram of the control area, FIG. 3 is a flowchart of the control, and FIG. This will be described with reference to these drawings.
[Configuration of vehicle drive system]
As shown in FIG. 1, the vehicle according to the present embodiment includes an engine (internal combustion engine) 1 at the front portion of the vehicle, and is configured as a front wheel drive vehicle (FF vehicle) configured with front wheels 4FR and 4FL as drive wheels. Has been. A transmission (transmission) 2 is connected to the output shaft 1a of the engine 1, and front wheels 4FR, 4FL are connected to the output shaft 2a of the transmission 2 via a differential mechanism (Differential) 3 with differential limiting control. ing.

  In this example, the differential mechanism 3 includes input bevel gears 32 and 32 mounted on the differential case 31, and output bevel gears 33R and 33L meshing with the input bevel gears 32 and 32 and coupled to the right front wheel 4FR and the left front wheel 4FL, respectively. Bevel gear type is used. Further, the bevel gear 2 b equipped on the output shaft 2 a of the transmission 2 meshes with the ring gear 31 a equipped on the differential case 31.

  As a result, the rotation of the engine 1 is transmitted from the engine output shaft 1a to the transmission 2 to be shifted, and is transmitted from the transmission output shaft 2a to the differential case 31 through the gears 2b and 31a, so that the differential case 31 rotates. The rotation of the differential case 31 is transmitted through the input bevel gears 32 and 32 and the output bevel gears 33R and 33L while allowing the differential to the front wheels 4FR and 4FL which are the left and right drive wheels.

As the differential mechanism 3, for example, a planetary gear type may be used and another type may be used.
A differential limiting mechanism (LSD: Limited Slip Differential) 5 provided in the differential mechanism 3 is interposed between one wheel (here, the right front wheel) 4FR and the differential case 31, and in this embodiment, an electromagnetic multi-plate. The clutch 51 is used, and the multi-plate clutch 51 is engaged according to the magnetic force generated according to the control amount (for example, control current), and the differential between the single wheel (right front wheel) 4FR and the differential case 31 is limited. To do. If the differential between the right front wheel 4FR and the differential case 31 is limited, naturally, the differential between the left front wheel 4FL and the differential case 31 is also limited.

In order to control the LSD 5, the LSD controller 11 is provided, and the LSD controller 11 operates the LSD 5 to limit the differential when one of the left and right drive wheels 4FR and 4FL is in the idling state. That is, the LSD 5 is configured as an electronically controlled LSD.
In the LSD controller 11, the idling of the drive wheel is determined based on the detection results of the wheel speed sensors 21FR to 21RL that detect the wheel speed of each wheel from the reference wheel speeds 4RR and 4RL (vehicle speed). And the wheel speeds of the drive wheels 4FR and 4FL are compared with the reference wheel speed. That is, if the average value of the wheel speeds of the rear wheels 4RR and 4RL is set as the reference wheel speed, and the wheel speed of any of the drive wheels 4FR and 4FL becomes larger than the reference wheel speed by more than a preset wheel speed difference. It is determined that the vehicle is idling. However, during turning, the wheel speed of the inner turning wheel decreases and the wheel speed of the outer turning wheel increases according to the turning radius, so this point is corrected and determined.

The differential restriction by the LSD 5 is performed with a control amount corresponding to the degree of the idling state of the wheel (for example, the wheel speed of the idling wheel / the reference wheel speed).
The condition for operating the LSD 5 may be a case where a torque difference greater than or equal to a predetermined value is generated in the left and right drive wheels, or a case where the difference in rotational speed between the left and right wheels becomes a predetermined value or more, instead of the idling state. Alternatively, it is also possible to provide a plurality of conditions for the idling state, the torque difference greater than or equal to a predetermined value, and the rotation speed difference greater than or equal to a predetermined value, and to set the LSD 5 to operate when any of these conditions is met.

Also, the difference in torque between the left and right drive wheels can be obtained by detecting the torque of each wheel and calculating the difference, and can be varied depending on the change in mechanical characteristics caused by the torque difference such as the tooth surface resistance of the gear. This can be realized by configuring the plate clutch 51 to be engaged.
The rotational speed difference between the left and right drive wheels can be obtained by detecting the wheel speed of each wheel and calculating the difference. Also in this case, during turning, the wheel speed of the inner turning wheel decreases and the wheel speed of the outer turning wheel increases according to the turning radius.

  Further, the differential limitation by the LSD 5 is performed by a control amount corresponding to the degree of torque difference between the left and right drive wheels, or the left and right drive, similarly to the case of performing the control amount according to the degree of the idling state of the wheel. It is also preferable to carry out with a control amount according to the degree of difference in the rotation speed of the wheel.

[Configuration of vehicle braking system]
The brake mechanisms 6FR, 6FL, 6RR, 6RL of the front wheels 4FR, 4FL and the rear wheels 4RR, 4RL can be controlled independently. That is, each of the brake mechanisms 6FR to 6RL has a brake rotor 6a that rotates together with the wheel and a brake caliper 6b that sandwiches and locks the brake rotor 6a, and the brake caliper 6b controls the operation independently for each brake mechanism of each wheel. Is done. The brake mechanisms 6FR to 6RL are also integrated and called a braking force adjustment mechanism.
In order to control each brake mechanism 6FR-6RL, the brake controller 12 is equipped, and the brake controller 12 normally operates each wheel 4FR-4RL by brake pedal operation according to the depression amount of the brake pedal which a driver operates. Each wheel is braked at the same time, but when the vehicle yaw direction control (steer control) is required when the vehicle is turning, the wheels 4FR to 4RL are individually braked to control the yaw movement of the vehicle body.

[Configuration of vehicle steering system]
The front wheels 4FR and 4FL are steered according to the steering angle θ of the steering wheel through a mechanism such as a rack and pinion connected to the tip of a shaft (not shown) of a steering wheel (not shown).
In addition, a steering angle sensor 22 is provided as a steering angle detection means for detecting the steering angle θ of the steering wheel, and the steering angle θ detected by the steering angle sensor 22 is input to the vehicle ECU 10. Similarly, a steering torque sensor 23 is provided as a steering torque detection means for detecting the steering torque τ of the shaft through the steering wheel, and the steering torque τ detected by the steering torque sensor 23 is input to the vehicle ECU 10.

[LSD integrated control]
Incidentally, FIG. 2 shows the possible steering torque τ of the driver with respect to the steering angle θ and the pros and cons of the LSD operation at that time.
A curve indicated by a solid line in FIG. 2 indicates a reference correlation of the steering torque τ corresponding to the steering angle θ. This reference correlation shows a general correspondence relationship of steering torque τ (hereinafter referred to as reference holding torque) necessary to hold a certain steering angle θ. When the driver applies this reference holding torque corresponding to the steering angle θ as the steering torque τ through the steering wheel, normally, the force that the steering system tries to return to neutral becomes the steering reaction force. The rudder torque is balanced and the rudder angle is maintained. When increasing the steering angle θ, the driver needs to apply a torque larger than the reference steering torque, and when switching back to decrease the steering angle θ, the driver applies a torque smaller than the reference steering torque. Become. At the time of the latter switching back, the torque applied in the direction of the steering angle θ is decreased. Usually, however, a negative torque, that is, a torque opposite to the direction of the steering angle θ is applied to perform the switching back quickly. In the reference correlation, as the steering angle θ increases, the steering torque τ increases, and when the steering angle θ increases to some extent, the steering torque τ reaches a peak. This correlation also changes depending on the vehicle speed.

  Here, from the state where the steering torque τ and the steering angle θ are equal, the steering reaction force may change due to the torque steer generated by the operation of the LSD 5, and the reaction force direction may be reversed. The direction of the steering torque required for the vehicle is reversed to enter the state of the LSD reduction region of FIG. 2, and the driver must apply the torque applied to the steering wheel in the opposite direction (the LSD torque reduction of FIG. 2). Area), steering feeling deteriorates.

  Therefore, in this apparatus, as shown in FIG. 3, the vehicle ECU (vehicle electronic control unit) 10 as the control means controls the LSD 5 in the driving range where the direction of the steering torque τ and the direction of the steering angle θ are different. Try to reduce the amount. However, as shown in the drawing, even in the driving region where the direction of the steering torque τ and the direction of the steering angle θ are different, in the region where the steering angle θ is small, emphasis is placed on the neutral steering feeling and the control amount of the LSD 5 Not limited. That is, the control amount of the LSD 5 is decreased only when the steering angle θ is equal to or greater than a certain value and the direction of the steering torque τ is different from the direction of the steering angle θ.

That is, the vehicle ECU 10 determines the sign (positive / negative) by comparing the steering angle θ detected by the input steering angle sensor 22 with 0, and compares the steering torque τ detected by the steering torque sensor 23 with 0. The sign (positive or negative) is determined, and it is determined whether the sign of the steering angle θ and the sign of the steering torque τ do not match. At the same time, it is determined whether or not the absolute value of the steering angle θ is greater than or equal to a threshold value (θ _th ) (that is, whether or not the LSD torque reduction region is reached). If the sign of the steering angle θ and the sign of the steering torque τ do not match and the absolute value of the steering angle θ is equal to or greater than the threshold value (θ _th ), it is determined that the region is in the LSD reduction region. At the time of LSD torque reduction determination, the control amount (differential control amount) of LSD 5 is multiplied by a control gain (<1) to be reduced.

  Further, when the vehicle ECU 10 is suppressing the control amount of the LSD 5 at the time of the LSD reduction determination, it is found that one of the wheel speeds is idle from the wheel speeds detected by the wheel speed sensors 21FR to 21RL. When each wheel idling detection means is used (the function for detecting idling of each wheel), the braking force is applied to the idling wheel by the braking force adjusting mechanism (brake mechanism) 6FR to 6RL. When this braking force is applied, a braking force according to the idling state of the idling wheel is added.

[Action and effect]
The differential limiting control apparatus according to the first embodiment of the present invention is configured as described above. For example, the control shown in FIG.
First, the steering angle θ and the steering torque τ input by the driver are read (step S10). Then, it is determined whether or not the sign of the steering angle θ and the sign of the steering torque τ are inconsistent (step S11), and it is determined whether or not the absolute value of the steering angle θ is larger than the threshold value (θ _th ) (step S11). S12). If the sign of the steering angle θ and the sign of the steering torque τ do not match and the absolute value of the steering angle θ is larger than the threshold value (θ _th ), the LSD 5 is operated with a control amount lower than usual ( Step S13) When the signs of the steering angle θ and the steering torque τ match or the absolute value of the steering angle θ is smaller than the threshold value (θ _th ), the LSD 5 is operated with a normal control amount (step S14).

  When the operation of the LSD 5 is restricted, it is determined whether any of the wheels is idling (step S15). If there is an idling wheel, the braking force adjusting mechanism (brake mechanism) 6FR to 6RL is applied to the idling wheel. Thus, the brake is operated (step S16), and the control flow is ended (END).

Since the differential limiting control device according to the first embodiment of the present invention is configured and operates as described above, the following effects can be obtained.
When the direction of the steering angle θ detected by the steering angle sensor 22 and the direction of the steering torque τ detected by the steering torque sensor 23 are different, the vehicle ECU 10 decreases the control amount (differential limit amount) of the LSD 5. Therefore, an extreme steering reaction force change due to torque steer can be suppressed, and the steering feeling can be maintained well.
For example, when a torque steer in which the driver has to generate a steering torque τ in a direction different from the direction of the steering angle θ occurs due to the differential restriction of the LSD 5 during steady turning, the driver is greatly discomforted.

  In addition, when switching back steering that applies torque in the direction of returning to neutral is performed, and a mismatch between the direction of the steering angle θ and the direction of the steering torque τ occurs, the differential restriction by the LSD 5 is applied to the driver. May give a sense of incongruity. In other words, the driver is sensitive to changes in the steering torque because the steering force is removed at the time of the return steering, and the acceleration is accompanied at the time of the return steering. Yes, and sensitive to changes in steering torque.

On the other hand, when the direction of the steering angle θ and the direction of the steering torque τ are different, the control amount (differential limit amount) of the LSD 5 is reduced, so that the change in the steering reaction force can be suppressed. Feeling can be maintained well.
Of course, there is a case where the direction of the steering angle θ and the direction of the steering torque τ are the same during the return steering. That is, there is switchback steering in the low frequency region in which the steering torque τ is decreased below the reference steering torque and the switchback is performed slowly. At this time, since the operation restriction of the LSD 5 is not performed, the differential restriction by the LSD 5 can be fully utilized to improve the stability and acceleration performance during high-speed traveling.

In addition, since the dead zone region in which the control amount (drive force difference) of the LSD 5 is not reduced is provided in the neutral region of the steering angle θ, a neutral steering feeling can be provided. In addition, the stability of this control can be improved.
Further, when the vehicle ECU 10 detects the idling of any wheel of the vehicle when the control amount of the LSD 5 is decreased, the braking force is applied to the idling wheel by the braking force adjusting mechanism (brake mechanism) 6FR to 6RL. Thus, the shortage of the differential limitation can be compensated.
In addition, by adding a braking force having a magnitude corresponding to the idling state of the idling wheel, the rotation of the idling wheel can be controlled appropriately.

Second Embodiment
Next, 2nd Embodiment of this invention is described using drawing.
5 to 7 show a control device for a differential limiting mechanism according to a second embodiment of the present invention. FIG. 5 is a diagram for explaining a limiting control region of the differential limiting mechanism, and FIG. FIG. 7 is a flowchart for explaining the control. This will be described with reference to these drawings. The configuration of the drive system will be described with reference to FIG.

[Configuration of vehicle steering system]
In FIG. 1, instead of the steering angle sensor 22, a steering angular velocity sensor 24 (shown by a two-dot chain line) as steering angular velocity detection means for detecting the steering angular velocity dθ of the steering wheel is provided, and the steering detected by the steering angular velocity sensor 24 is provided. The angular velocity dθ is input to the vehicle ECU 10. The steering angular velocity dθ may be calculated by time-differentiating the steering angle θ detected by the steering angle sensor 22 input to the vehicle ECU 10.
In addition, a steering torque sensor 23 is provided as a steering torque detecting means for detecting the steering torque of the shaft through the steering wheel, and the steering torque τ detected by the steering torque sensor 23 is input to the vehicle ECU 10.

[LSD integrated control]
FIG. 5 shows the steering torque τ of the driver that can be taken with respect to the steering angular velocity dθ and the appropriateness of the LSD operation at that time.
Note that a straight line shown by a solid line in FIG. 5 indicates a reference correlation of the steering torque τ corresponding to the steering angular velocity dθ. This reference correlation shows an example of a correspondence relationship of steering torque τ (hereinafter referred to as reference torque) necessary for steering at a certain steering angular velocity dθ. Here, the reference correlation is simply shown as a straight line. Not necessarily. Further, this reference correlation is based on neutral (steering angle θ = 0) as a reference. When a predetermined steering angle θ (other than 0) is considered as a reference, the reference steering torque ( The reference correlation is shifted or deformed by the amount corresponding to the reference correlation (see FIG. 2). In the reference correlation, the magnitude of the steering torque τ increases as the magnitude of the steering angular velocity dθ increases. This correlation also changes depending on the vehicle speed.

  Here, from the state where the direction of the steering torque τ and the direction of the steering angular velocity dθ are equal, the torque steer is generated by the operation of the LSD 5 and the steering reaction force is changed and reversed, and the direction of the steering torque required for the driver is changed. When reversed, the driver must apply a steering torque in the direction opposite to the turning direction to the steering wheel. Thus, when the direction of the steering torque τ and the direction of the steering angular velocity dθ become different due to the operation of the LSD 5 (the LSD torque reduction region in FIG. 5), the steering feeling is deteriorated.

  Therefore, in this apparatus, as shown in FIG. 6, the vehicle ECU 10 as the control means reduces the control amount of the LSD 5 in the driving region where the direction of the steering torque τ and the direction of the steering angular velocity dθ are different. Yes. However, as shown in the drawing, even in the driving region where the direction of the steering torque τ and the direction of the steering angular velocity dθ are different, in the region where the steering angular velocity dθ is small, the steering angle maintaining feeling is emphasized and the control amount of the LSD 5 Is not limited. That is, the control amount of the LSD 5 is reduced only when the steering angular velocity dθ is equal to or greater than a certain value and the direction of the steering torque τ is different from the direction of the steering velocity angle dθ.

That is, the vehicle ECU 10 determines the sign (positive / negative) by comparing the steering angular velocity dθ detected by the input steering angular velocity sensor 24 with 0, and compares the steering torque τ detected by the steering torque sensor 23 with 0. The sign (positive or negative) is determined to determine whether the sign of the steering angular velocity dθ and the sign of the steering torque τ do not match. At the same time, it is determined whether or not the absolute value of the steering angular velocity dθ is equal to or greater than a threshold value (dθ _th ) (that is, whether or not it is in the LSD torque reduction region). If the sign of the steering angular velocity dθ and the sign of the steering torque τ do not match and the absolute value of the steering angular velocity dθ is equal to or greater than the threshold value (dθ _th ), it is determined that the region is the LSD reduction region. At the time of LSD torque reduction determination, the control amount (differential control amount) of LSD 5 is multiplied by a control gain (<1) to be reduced.
Except for these configurations, the configuration is the same as that of the first embodiment.

[Action and effect]
Since the control device for the differential limiting mechanism according to the second embodiment of the present invention is configured as described above, for example, the control shown in FIG. 7 is performed by the vehicle ECU 10.
First, the steering angular velocity dθ and steering torque τ input by the driver are read (step S20). Then, it is determined whether or not the sign of the steering angular velocity dθ and the sign of the steering torque τ are inconsistent (step S21), and it is determined whether or not the absolute value of the steering angular velocity dθ is greater than a threshold value (dθ _th ) (step S21). S22). If the signs of the steering angular velocity dθ and the steering torque τ do not match and the absolute value of the steering angular velocity dθ is larger than the threshold value (dθ _th ), the LSD 5 is operated with a controlled amount lower than normal (step S23), and the steering is performed. When the sign of the angular velocity dθ coincides with the sign of the steering torque τ, or the absolute value of the steering angular speed dθ is smaller than the threshold value (dθ _th ), the LSD 5 is operated with a normal control amount (step S24).
When the operation of the LSD 5 is restricted, it is determined whether any of the wheels is idling (step S25), and if there is an idling wheel, the braking force adjusting mechanism (brake mechanism) 6FR to 6RL for the idling wheel. Thus, the brake is operated (step S26), and the control flow is ended (END).

Since the differential limiting control device according to the second embodiment of the present invention is configured and operates as described above, the following effects can be obtained.
The vehicle ECU 10 decreases the control amount (differential limit amount) of the LSD 5 when the direction of the steering angular velocity dθ detected by the steering angular velocity sensor 24 and the direction of the steering torque τ detected by the steering torque sensor 23 are different. Therefore, an extreme steering reaction force change due to torque steer can be suppressed, and the steering feeling can be maintained well.
For example, when the LSD 5 is activated to change the steering reaction force and the direction of the steering torque τ input by the driver differs from the direction of the steering angular velocity dθ of the steering wheel, the driver feels uncomfortable.

In addition, when performing steering in the high frequency range, which is quick switchback steering by increasing the steering torque τ from the reference torque and applying the steering torque in the opposite direction to the reference torque, such as during slalom running, the difference occurs. When the movement limiting mechanism is activated and a change in the steering reaction force occurs, the driver may feel uncomfortable.
On the other hand, when the direction of the steering angular velocity dθ and the direction of the steering torque τ are different, the control amount (differential limit amount) of the LSD 5 is decreased, so that the change in the steering reaction force can be suppressed, and the steering Feeling can be maintained well.

  Of course, when the direction of the steering angular velocity dθ and the direction of the steering torque τ are the same, the operation restriction of the LSD 5 is not performed. Therefore, the differential restriction by the LSD 5 is fully utilized, and the stability and acceleration performance at high speed driving are performed. Etc. can be improved.

[Others]
Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.
For example, in this embodiment, an FF vehicle has been described, but an FR vehicle (front engine / rear drive vehicle), an RR vehicle (rear engine / rear drive vehicle), and a 4WD vehicle (four-wheel drive) are also equipped with LSD. The present invention can be applied to any vehicle.
In the first embodiment, when the direction of the steering angle θ and the direction of the steering torque τ are different, the control amount of the LSD 5 is decreased. In the second embodiment, the direction of the steering angular velocity dθ and the steering torque τ Although the control amount of the LSD 5 is reduced when the direction is different, the control may be performed in combination.

That is, when the direction of the steering angle θ and the direction of the steering torque τ are different, and also when the direction of the steering angular velocity dθ and the direction of the steering torque τ are different, the vehicle ECU 10 decreases the control amount of the LSD 5. It is also possible to make it.
In the above embodiment, direct control of the LSD 5 is performed by the LSD controller 11 and direct braking control of each of the wheels 4FR to 4RL is performed by the brake controller 12, respectively. Various configurations of the control device (control means) are conceivable, such as the functions of the brake controller 12 and any control performed by the vehicle ECU 10 collectively.

  The present invention can be widely applied to vehicles equipped with a differential limiting mechanism (LSD).

1 engine (internal combustion engine)
2 Transmission 2b Bevel gear 3 Differential mechanism
4FR, 4FL Front wheel 5 LSD (Differential limiting mechanism)
6FR-6RL Brake mechanism (braking force adjustment mechanism)
10 Vehicle ECU (control means)
DESCRIPTION OF SYMBOLS 11 LSD controller 12 Brake controller 21FR-21RL Wheel speed sensor 22 Steering angle sensor (steering angle detection means)
23 Steering torque sensor (steering torque detection means)
24 Steering angular velocity sensor (steering angular velocity detection means)
31 Differential case 51 Multi-plate clutch

Claims (5)

In a vehicle having a differential limiting mechanism for limiting the differential between the left and right wheels of the vehicle, and a control means for controlling the differential limiting mechanism,
Steering angle detection means for detecting the steering angle of the vehicle input by the driver ;
Steering torque detection means for detecting the steering torque of the vehicle input by the driver ,
Wherein, the direction of the steering angle detected by the pre-Symbol steering angle detection means, when the the direction of the detected steering torque varied with the steering torque detecting means reduces the amount of control of the differential limiting mechanism A control device for a differential limiting mechanism. In a vehicle having a differential limiting mechanism for limiting the differential between the left and right wheels of the vehicle, and a control means for controlling the differential limiting mechanism,
Steering angular velocity detection means for detecting the steering angular velocity of the vehicle input by the driver ;
Steering torque detection means for detecting the steering torque of the vehicle input by the driver ,
Wherein, the direction of the front Symbol steering angular velocity detected by the steering angular velocity detecting means, when the the direction of the detected steering torque varied with the steering torque detecting means reduces the amount of control of the differential limiting mechanism A control device for a differential limiting mechanism. 3. The differential limiting mechanism according to claim 1, wherein a dead zone region in which the control amount is not reduced is provided in a neutral region of the steering angle or a region near zero of the steering angular velocity. Control device. A braking force adjusting mechanism for making a difference in the braking force of each wheel of the vehicle;
Each wheel idling detection means for detecting idling of each wheel of the vehicle,
When the control means detects the idling of any wheel of the vehicle by the wheel idling detection means when the control amount of the differential limiting mechanism is reduced, the braking force adjusting mechanism is used to detect the idling wheel. The control device for a differential limiting mechanism according to any one of claims 1 to 3, wherein a braking force is applied. The control means, when adding a braking force to the idle wheel by the braking force adjusting mechanism, adds a braking force having a magnitude corresponding to an idle state of the idle wheel. 4. The control device for the differential limiting mechanism according to 4.

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