JPH11348595A - Driving/bracking/control device for right and left wheels for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve turning performance for a vehicle without increasing the cost of a device, increase of its weight and the like, by using a brake device which can separately brake a mechanical limited slip differential and respective right and left driving wheels. SOLUTION: This control device is provided with left and right driving wheels 10L, 10R, a mechanical limited slip differential 12 for transmitting driving force outputted from an engine with differentially limiting it to the left and right driving wheels 10L, 10R, and a brake device 20 respectively provided for the left and right driving wheels 10L, 10R, and the limited slip differential 12 has a one-way clutch 18 allowing differential limiting only when the driving force inputted from the engine is in the advance direction. During advancing acceleration turn of a vehicle, a given braking force can be impressed with the brake device 20 to the driving wheel on the turning inner wheel side of the left and right driving wheels 10L, 10R.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a left and right vehicle for a vehicle capable of controlling the driving force of a left and right driving wheel to which a driving force is transmitted through a mechanical limited slip differential by utilizing braking control by a brake device. The present invention relates to a drive braking control device for wheels.

[0002]

2. Description of the Related Art In recent years, techniques for controlling driving force and braking force of left and right wheels of a vehicle (automobile) have been developed. For example, a limited slip differential has been developed in order to reliably transmit a driving force from an engine to left and right driving wheels (hereinafter, simply referred to as left and right wheels). This limited slip differential is
Distributes the driving force to the left and right wheels while allowing the left and right wheels to differentiate, and when one of the drive wheels slips, the difference between the left and right wheels increases, limiting this differential and suppressing the slip of one of the drive wheels Thus, it is possible to transmit the driving force to the other driving wheel.

[0003] Such a limited slip differential (hereinafter, referred to as "slip differential")
There are various types of LSDs, and these LSDs are interposed between an input side to which driving force from an engine is input and an output side to output driving force to driving wheels, and are generally provided. , Provided between the left and right driving wheels of the rear wheel. For example, in the case of a mechanical LSD, the differential itself is configured such that the driving force from the engine is input from the differential case and output to the respective drive shafts of the left and right wheels via a pinion and a side gear meshing with each other. The friction disk is configured such that a friction disk that rotates integrally with the differential case and a friction disk that rotates integrally with the side gear are brought into sliding contact with each other.

When a differential occurs between the input and output shafts (between the differential case and the side gears), the differential limiting mechanism acts to reduce the differential. Therefore, when one of the drive wheels slips, a differential is generated between the one drive wheel-side side gear and the differential case, and between the other drive wheel-side side gear and the differential case. Movement is suppressed.

[0005] By this differential suppression, useless rotation of the driving wheel on the slipping (large slip) side is suppressed, and the driving wheel on the non-slip (or low slip) side is surely provided. The driving force is transmitted, and the traveling performance of the vehicle is ensured. In particular, only when a driving force from the engine is input to the LSD, a mechanical LS with a clutch equipped with a clutch that enables the differential limiting clutch to be engaged.
A mechanical LSD with a one-way clutch has also been developed that includes a one-way clutch that enables the differential limiting clutch to be engaged only when a driving force in the forward direction is input to the D or the LSD from the engine.

On the other hand, an anti-lock brake system (ABS) has also been proposed in which the locking tendency is determined for each wheel so that the braking force can be reduced and controlled if the locking tendency is detected so that the locking of the wheels during braking can be prevented. It has been developed and put into practical use. In the case of a vehicle equipped with such an ABS, if the above-mentioned mechanical LSD with a one-way clutch is provided, the LSD does not work at the time of braking when the driving force from the engine is not input, so that the LSD does not interfere with the ABS. Absent.

At the start of turning of the vehicle, it is necessary to turn the vehicle in the turning direction, and the turning of the vehicle is performed by turning the steered wheels (front wheels). When restricted, turning of the vehicle is suppressed. This suppression of turning can be achieved if differential tacking is effective and steering characteristics are improved when tack-in is more likely than necessary at the start of turning (when over-steering tendency is large). It is not preferable because it hinders quick turning of the head.

Therefore, in the case of a mechanical LSD with a clutch, if it is desired to turn the vehicle, it is sufficient to prevent the driving force from the engine from being input to the LSD by turning off the accelerator, and to suppress the turning of the vehicle, The driving force from the engine may be input to the LSD as the accelerator is turned on. Therefore, using such a mechanical LSD, for example, during sports running on a winding road or the like, it is possible to perform a high-speed turn while driving the vehicle stably while utilizing the change in the steering characteristic by the driving operation of the driver. It is also possible to do.

However, such a driving operation not only requires advanced driving skills of the driver, but also sets the steering characteristics of the vehicle, sets the lock ratio of the mechanical LSD, and sets the initial torque (mechanical type with clutch). It is necessary to appropriately set the minimum driving force at which the clutch of the LSD can be engaged. However, increasing the lock rate increases hysteresis, making it difficult for the driver to steer with the throttle, and increasing the initial torque makes it difficult to rotate (turn) at the beginning of turning. In fact, the vehicle's steering characteristics, lock rate,
It is difficult to properly set the initial torque.

In the case of a mechanical LSD, there is also a characteristic that a single wheel has a large shock input. In addition to the mechanical LSD, a viscous coupling unit (VC
U), etc., but in this case, the inner wheel torque during turning is always larger than the outer wheel torque, so that the front wheel assist by the left and right wheel drive control of the rear wheels during the marginal operation of the vehicle is not possible. When there is a problem that it is possible and there is a problem that the acceleration performance on the uneven road is low, the mechanical LSD is more convenient when aiming to improve the turning performance as described above.

By the way, in the case of the mechanical LSD, it is difficult to turn the vehicle along a curve while accelerating on a curved road, no matter how advanced the driver has the driving skill. That is, in order to accelerate, it is necessary to apply a forward drive force to the drive wheels, and the drive force is applied to the mechanical LSD to limit the differential, thereby making it difficult for the vehicle to turn.

[0012] Therefore, not only limiting the differential to suppress the slip of the wheels, but also actively controlling the distribution of the driving force to the left and right wheels (particularly, the rear wheels), the turning performance of the vehicle is improved. LSDs that can be improved have also been developed. Examples of the LSD that can be actively controlled in this manner include a torque transfer type LSD and an electromagnetic clutch type LSD.
There is an SD, for example, by turning off the differential limitation as needed while accelerating, it is possible to improve the turning performance.

In the case of a torque transfer type LSD, for example, a multi-plate clutch capable of freely controlling the state of compression between an input side to which the driving force of the engine is input and an output side to output the driving force to the left and right driving wheels. The multi-plate clutch is controlled so as to adjust the differential limiting force by controlling the pressure. In the case of the electromagnetic clutch type LSD, a pilot clutch is provided in addition to the main clutch directly involved in the differential limitation, and the armature is driven by adjusting the power to the electromagnetic coil to crimp the pilot clutch, so that the crimp of the main clutch can be performed. When the differential occurs between the left and right wheels under the pressure of the pilot clutch, the main clutch is pressed to limit the differential between the left and right wheels.

[0014]

However, in the case of the above-mentioned torque transfer type LSD, the outer ring torque can be made larger than the inner ring torque at the time of turning, and the rotation at the beginning of turning is easy to produce, but the outer ring torque is sufficiently increased. To be able to do so, the LSD must be large and heavy. In addition, since the torque is moved by the feedback control, there is a problem that the running stability during running on uneven roads or high-speed turning tends to decrease due to control delay.

Further, the electromagnetic clutch type LSD can also make the outer ring torque larger than the inner ring torque during turning.
Although it is easy to make rotation at the beginning of turning, there is a problem that the restraining torque on a pavement height μ road is insufficient. Although a combination of the above-described LSDs has been developed, there are problems such as an increase in the size of the device and an increase in cost.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and uses a mechanical limited slip differential and a brake device capable of separately braking left and right drive wheels, while increasing the cost and weight of the device. It is an object of the present invention to provide a drive braking control device for left and right wheels for a vehicle, which can improve the turning performance of the vehicle without inducing.

[0017]

According to the first aspect of the present invention, the driving force output from the engine is limited by a mechanical limited slip differential through a mechanical limited slip differential. While being transmitted to the left and right drive wheels. At this time, the limited slip differential has a one-way clutch, and performs the differential limitation only when the driving force input from the engine is in the forward direction.

At the time of forward acceleration turning of the vehicle, a required braking force is applied by the brake device to the driving wheel on the turning inner wheel side of the left and right driving wheels. As a result, while the driving torque to the driving wheel on the turning outer wheel side increases, the driving torque to the driving wheel on the turning inner wheel side is suppressed or does not increase slightly, and the turning outer wheel side is turned on the turning inner wheel side. The torque is sufficiently distributed more than the above, which contributes to the improvement of the turning performance.

[0019]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a drive braking control device for a vehicle according to an embodiment of the present invention; FIG. It is. The vehicle (automobile) according to the present embodiment is a four-wheel drive vehicle that can travel by transmitting engine driving force to left and right front wheels and left and right rear wheels, respectively. It is provided in.

That is, as shown in FIG. 1, the present drive braking control device includes a mechanical limited slip differential (hereinafter referred to as a mechanical LSD or simply LSD) 12 with a one-way clutch. Driving force from an engine (not shown) is transmitted to left and right driving wheels (hereinafter, also simply referred to as wheels) 10L and 10R.

In the mechanical LSD 12, the driving force from the engine is input to a differential case 12A, and the differential case 12A
The pinion 12B attached to the pinion A and the side gears 12L and 12R meshing with the pinion 12B
The transmission is transmitted to the rear wheel drive shafts 14L, 14R to which the left and right wheels L, 12R are coupled, and to the left and right drive wheels 10L, 10R coupled to the rear wheel drive shafts 14L, 14R.

A friction disk 16 is provided between the input side member and the output side member of the mechanical LSD 12.
A differential limiting mechanism 16 having A and 16B is interposed. That is, the plurality of friction disks 16A are driven by the drive wheels 10L and 10L so as to rotate integrally with the differential case 12A which is an input member to which the driving force from the engine is input.
Side gear 1 which is an output side member that outputs driving force to R
A plurality of friction disks 16B are provided so as to rotate integrally with the 2L, 12R or the rear wheel drive shafts 14L, 14R, respectively.

The mechanical LSD 12 is provided with a one-way clutch 18 that enables the friction disks 16A and 16B to be engaged with each other only when a forward driving force is input from the engine. The input side member (differential case 12)
A) and the output-side members (side gears 12L, 12R) cause a differential, and a driving force (torque) is transmitted from the high-speed rotation side to the low-speed rotation side between the friction disks 16A, 16B. ing.

Conversely, if the forward driving force is not input from the engine, even if the input side member (differential case 12A) and the output side member (side gears 12L, 12R) produce a differential,
Due to the function of the one-way clutch 18, the friction disks 16A and 16B are not engaged, and the transmission of the driving force (torque) between the left and right wheels is not performed.

Further, a brake device 20 capable of separately applying a braking force to the left and right drive wheels 10L, 10R is provided. That is, each of the drive wheels 10L and 10R is provided with a caliper 22, and each of the calipers 22 is
By applying the brake pressure inside the brake cylinder,
The brake pad 22B is pressed against the brake disc 22A to apply a braking force to the wheels.

For this purpose, the brake device 20 is provided with a brake circuit 24 for controlling the brake pressure in the brake cylinder of each caliper 22. The brake circuit 24 includes a brake fluid tank 26, brake fluid supply paths 28A, 28B, 28C interposed between the brake fluid tank 26 and the calipers 22, 22, brake fluid supply / discharge paths 30A, 30B, Brake fluid discharge paths 32A, 32
B, 32C.

A motor 34 is provided in the brake fluid supply path 28A.
A pump 34 driven by A and a pressure accumulator 36 are interposed. Further, between the brake fluid supply path 28B and the brake fluid discharge path 32B and the brake fluid supply / discharge path 30A, and between the brake fluid supply path 28C and the brake fluid discharge path 32C and the brake fluid supply / discharge path 30B, Supply / discharge switching valves (proportional valves) 38L and 38R are provided respectively.

Each of the supply / discharge switching valves 38L, 38R has a CP
Through U40, control is performed based on braking hydraulic pressure (brake pressure), each wheel speed of the rear wheels, front wheel speed, throttle opening, steering wheel angle, lateral G of the vehicle body, intake pressure, and the like. That is, a pressure sensor 42 that detects a hydraulic pressure (brake pressure) of the master cylinder that changes according to the depression of a brake pedal (not shown), pressure sensors 42L and 42R that detect a braking hydraulic pressure near each caliper 22, and each wheel of the rear wheels Wheel speed sensor 44 for detecting wheel speeds of 10L and 10R
L, 44R, a wheel speed sensor 46 for detecting each wheel speed of the front wheels, a throttle opening sensor 48 for detecting a throttle opening, and a steering wheel angle sensor 50 for detecting a steering wheel angle.
, A lateral G sensor 52 for detecting the lateral G of the vehicle body, an intake pressure sensor 54 for detecting the intake pressure of the engine, and the like. The CPU 40 switches between supply and discharge based on the detection information from these sensors. The valves 38L and 38R are controlled.

For example, when a brake pedal (not shown) is depressed, the hydraulic pressure of the master cylinder rises and the pressure sensor 42
Detects this, the CPU 40 sets the supply / discharge switching valves 38L and 38R to the brake fluid supply state, and
The brake fluid is supplied to each caliper of a front wheel brake (not shown), the brake fluid supply passage 28B and the brake fluid supply / discharge passage 30A are communicated, and the brake fluid supply passage 28B and the brake fluid supply / discharge passage 30B are communicated. Left rear wheel 10L
The brake fluid is supplied to the caliper 22 of the right rear wheel 10R and the caliper 22 of the right rear wheel 10R to apply a braking force to each wheel.

When the brake pedal is depressed, anti-lock brake control is also performed, and the rotational speed of each wheel (left and right front wheels and left and right rear wheels) is monitored through wheel speed sensors 44L, 44R and 46. On the other hand, with respect to the wheel having a tendency to lock, the brake fluid is discharged or stopped to reduce the braking force, the grip force of the wheel is restored, and the wheel is locked without causing the wheel to lock. It is possible to perform reliable braking while securing the grip power of.

Further, the CPU 40 performs control (hereinafter referred to as drive braking control) for accelerating the rotation (turning) of the vehicle by applying a braking force to one of the left and right wheels at the time of turning acceleration or braking turning. Has become. First, the drive braking control at the time of turning acceleration will be described. In other words, when turning while accelerating the vehicle, the accelerator pedal is depressed, the throttle opens, and the mechanical LSD
Since the forward driving force is input to the LSD 12, the mechanical LSD 12
Of the input side member (differential case 12A) and the output side member (side gears 12L, 12L).
2R), the differential limiting mechanism 16 operates to limit the differential between the left and right wheels. If the differential between the left and right wheels is restricted during turning, rotation (turning) of the vehicle body in the turning direction is hindered, and turning performance is reduced.

Therefore, at the time of turning acceleration, a braking force is applied to the wheels on the turning inner wheel side to forcibly generate a differential between the left and right wheels (turning inner and outer wheels), thereby promoting rotation (turning) in the turning direction of the vehicle body. I am trying to do it. In this case, it is necessary to know whether or not the vehicle is turning, whether or not the vehicle is accelerating, and which of the left and right wheels is the turning inner wheel,
If the braking force applied to the turning inner wheel is too large, the rotation of the vehicle becomes excessive. Therefore, it is necessary to appropriately set how the braking force is applied to the turning inner wheel.

In this device, acceleration is determined based on the intake pressure of the engine detected by the intake pressure sensor 54. In other words, the intake pressure increases during acceleration,
When the intake pressure becomes equal to or higher than a preset threshold value, the vehicle is accelerating (that is, when the forward driving force of the engine
D12).

Further, which of the left and right wheels is the turning inner wheel is determined based on the steering wheel angle θh detected by the steering wheel angle sensor 50 and the lateral G generated in the vehicle detected by the lateral G sensor 52. It has become. That is, the steering wheel angle θh indicates a right turn (the steering wheel angle θh increases in the right turning direction by a predetermined increase rate or more), and the lateral G of the vehicle indicates a right turning (the lateral turning of the vehicle in the left direction). G is generated), it is determined that the vehicle is in a right turn state and the right wheel is a turning inner wheel. Conversely, the steering wheel angle θh indicates a left turn (the steering wheel angle θh increases by a predetermined amount in the left turning direction). If the lateral G of the vehicle indicates a left turn (the lateral G occurs in the right direction of the vehicle), it is determined that the vehicle is in a left turn state and the left wheel is an inner wheel for turning. The judgment is made.

As described above, the determination of the turning inner wheel to be controlled is performed not only by using the steering wheel angle θh but also by using the lateral G because the braking control is performed when the steering wheel is further turned and the braking control is not performed when the steering wheel is returned. That's why. In other words, when turning, when the steering wheel is turned further (when the steering wheel angular velocity in the turning direction becomes larger than a predetermined value), the braking force is applied to the turning inner wheel for a short period of time,
This is because the turning of the vehicle in the turning direction can be promoted, and it is considered that it is not necessary to accelerate the turning of the vehicle in, for example, an accelerated turning in which the steering wheel is not turned further as in a steady turning.

Of course, whether or not the steering wheel is turned further depends on the threshold value used for the determination. Therefore, depending on how the determination threshold value is set in this case, the degree of change in the steering wheel angle causes the inner wheel to be turned. It is possible to adjust the flavor of the control, such as whether to apply a braking force. Further, even if a change in the steering wheel angle that is simply equal to or larger than the threshold value occurs, the change in the steering wheel angle may be a steering wheel return operation at the end of turning. When returning such a handle, the mechanical LSD12
Since it is desired to promptly shift the vehicle to straight running by using the differential limiting mechanism 16 of this embodiment, the control for applying the braking force to the turning inner wheel is not performed. In the present device, when the turning direction determined based on the steering wheel angle θh (the increasing / decreasing direction of the steering wheel angle θh) and the turning direction determined based on the lateral G are different,
The control for applying the braking force to the turning inner wheel by determining that the steering wheel is being returned is not performed.

When a braking force is applied to the turning inner wheel, for example, as shown in FIG. 7, the inner wheel brake pressure is set within a certain pressure range (eg, 0.05 to 0.1 MPa) of the mechanical LSD 12 in the initial stage. It is increased by a predetermined time T1 within a range corresponding to the torque. The predetermined time T1 is set according to the characteristics of the vehicle. The initial torque of the mechanical LSD 12 refers to the initial torque (restraint force) applied to the LSD in advance with the mechanical LSD in order to prevent drive loss during traveling on uneven roads or to improve the stability of the vehicle during turning. This means that this device obtains the initial torque by braking.

Next, drive braking control (including anti-lock brake control) during braking turning will be described. At the time of braking, the anti-lock brake control is performed in the control area (the area of the anti-lock brake control). That is,
If the rotation speed deviation between the minimum speed wheel and the maximum speed wheel among the four wheels is equal to or more than a predetermined ratio (for example, 8%), it is determined that one of the wheels indicates a locking tendency and the brake pressure of the required wheel is determined. To prevent wheel lock.

The anti-lock brake control is performed as in the conventional case. However, in the conventional brake control, when the brake is turned off (depressing the brake pedal is completed), the brake pressure is immediately reduced to 0 to eliminate the braking force. However, in the brake control of this apparatus, when the vehicle is turning (generally at the start of turning) when the brake is turned off, as shown by the solid line in FIG. After holding for a short time, it is set to 0. At this time, on the turning outer wheel side, the brake pressure is reduced to 0 at the same time when the brake is turned off (see the decrease characteristic indicated by the broken line in FIG. 8).

To do this, it is necessary to determine whether the brake is on or off, to determine whether the vehicle is turning,
It is necessary to determine which of the left and right wheels is the inner wheel, and it is necessary to set how much brake pressure is to be held for the turning inner wheel. In this device, the brake pressure near the master cylinder detected by the pressure sensor 42 is compared with a preset threshold, and if the brake pressure is equal to or higher than the threshold, it is determined that the brake is on, and the brake pressure is lower than the threshold. , The brake is determined to be off.

The steering angle sensor 50 determines whether the vehicle is turning and whether the left or right wheel is an inner wheel.
Is performed on the basis of the steering wheel angle θh detected in the step (1). That is, when the steering wheel angle θh indicates a right turn (the steering wheel angle θh increases in the right turning direction by a predetermined increase rate or more), the vehicle is in a right turning state, and the right wheel is the inner turning wheel. Conversely, if the steering wheel angle θh indicates a left turn (the steering wheel angle θh increases by a predetermined rate or more in the left turning direction), the vehicle is in a left turning state, and the left wheel is a turning inner wheel. Is determined.

Here, the turning direction is determined using only the steering wheel angle θh and not using the lateral G. However, this is because only the additional turning of the steering wheel (start of turning) is considered in the drive braking control during the braking turn. This is because there is no need to consider turning back the steering wheel. That is, in general, the braking timing at the time of turning is before entering the curve, and the brake is turned on from off just before entering the curve or at the time of entering the curve, and the brake is operated from on to off in the process of exiting the curve. It is usually not possible to do so.

When delaying the elimination of the braking force of the turning inner wheel during braking turning, for example, as shown by a solid line in FIG. 8, the inner wheel brake pressure is reduced to 0 after being held for a predetermined time T2. . The predetermined time T2 is set according to the characteristics of the vehicle.
It is conceivable to set it within a range of about seconds. Since the drive braking control device for the left and right wheels for a vehicle as one embodiment of the present invention is configured as described above, the drive braking control is performed, for example, as shown in the flowcharts of FIGS.

First, as shown in FIG. 2 (control main routine), a pressure signal in the intake pipe of the engine (intake pressure), a lateral acceleration (lateral G) signal of the vehicle, a steering wheel angle signal, a braking hydraulic signal for the rear left and right wheels, etc. , The respective wheel speed signals and the like are fetched from the corresponding sensors (step A10), and it is determined, for example, from the brake oil pressure signal whether the brake is on (step A2)
0). If the brake is off, acceleration control (turning acceleration control) is performed (step A30), and if the brake is on, braking control (brake turning control) is performed (step A40).

In the acceleration control (turning acceleration control), as shown in FIG. 3, first, it is determined whether or not the vehicle is accelerating (step B10). That is, when the intake pressure of the engine detected by the intake pressure sensor 54 becomes equal to or higher than the preset threshold, the vehicle is accelerating (that is, the forward driving force of the engine is input to the mechanical LSD 12). judge. If the vehicle is accelerating, set the turning direction (step B
20) Then, the inner wheel brake pressure is controlled based on this setting (step B30).

The turning direction setting in step B20 is as follows.
As shown in FIG. 4, first, in steps C10 and C20, it is determined whether or not the vehicle is turning. That is, it is determined whether the steering wheel is turned right (step C1).
0). For example, when the steering wheel angle θh increases in the right turning direction by a predetermined increase rate or more, it is determined that the steering wheel is turned right. If the handle is not turned right, it is determined whether the handle is turned left (step C20). Also in this case, for example, when the steering wheel angle θh increases by a predetermined rate or more in the left turning direction, it is determined that the steering wheel is turned left.
Here, if the steering wheel is not turned left, it is determined that the steering wheel is neutral (the vehicle is traveling straight instead of turning) (step C30).

On the other hand, if the steering wheel is turned right, the process proceeds from step C10 to step C40 to determine whether or not the lateral G of the vehicle indicates a right turn (the lateral G is generated in the left direction of the vehicle). judge. Here, if the side G of the vehicle indicates a right turn, it is at the time of turning the steering wheel accompanying the start of the turn,
It is determined that the vehicle is turning right, and it is determined that the right wheel is a turning inner wheel (step C60).

If the steering wheel is turned left, the process proceeds from step C20 to step C50 to determine whether or not the lateral G of the vehicle indicates a left turn (the lateral G occurs in the right direction of the vehicle). I do. Here, if the side G of the vehicle indicates a left turn, it is a time when the steering wheel is further turned at the start of the turn,
It is determined that the vehicle is turning left, and the left wheel is determined to be a turning inner wheel (step C70).

Step C40 or step C50
If N (No), the inner ring setting is not performed. When the turning inner wheel is thus set, the inner wheel brake pressure control is performed based on this setting (step B3 in FIG. 3).
0). In this inner wheel brake pressure control, for example, as shown in FIG.
In the range corresponding to the initial torque of the mechanical LSD 12, the pressure is increased by a predetermined time T1.

By such inner-wheel brake pressure control, the vehicle can be accelerated and the turning in the turning direction of the vehicle can be promoted while the differential limitation by the mechanical LSD 12 is applied. Performance can be improved. On the other hand, in the braking control (braking turning control), first, as shown in FIG. 5, it is determined whether or not it is in a control area (an area of anti-lock brake control) (step D10). In this determination, if the rotation speed deviation between the minimum speed wheel and the maximum speed wheel among the four wheels is equal to or more than a predetermined ratio (for example, 8%), it is determined that one of the wheels indicates a lock tendency and the control area is determined. And

If it is in the control area, the brake pressure is reduced for the required wheels, that is, the rear wheels that are slower than the high-speed wheels among the left and right front wheels to prevent the wheels from locking (step D20). ). Then, it is determined whether the brake has been switched from on to off (step D3).
0). That is, when the detected brake pressure falls from the state equal to or higher than the preset threshold to the level lower than the threshold, it is determined that the brake has been switched off.

When the brake is switched off, the turning direction is set and the inner wheel brake pressure is controlled (step D40). In the setting and control in step D40, as shown in FIG. 6, first, in steps E10 and E20, it is determined whether or not the vehicle is turning. That is, it is determined whether the steering wheel is turned right (step E1).
0). For example, when the steering wheel angle θh increases in the right turning direction by a predetermined increase rate or more, it is determined that the steering wheel is turned right. If the handle is not turned right, it is determined whether the handle is turned left (step E20). Also in this case, for example, when the steering wheel angle θh increases by a predetermined rate or more in the left turning direction, it is determined that the steering wheel is turned left.
Here, if the steering wheel is not turned left, it is determined that the steering wheel is neutral (the vehicle is traveling straight instead of turning) (step E30).

On the other hand, if the steering wheel is turned right, the process proceeds from step E10 to step E40, assuming that the right wheel is the turning inner wheel, and the brake pressure of the right inner wheel is left for a set time. If the steering wheel is turned left, the process proceeds from step E20 to step E50, assuming that the left wheel is the turning left wheel, and the brake pressure of the left inner wheel is left for a set time. That is, the outer wheel brake pressure is reduced to 0 immediately after the brake is turned off, but the inner wheel brake pressure is reduced to 0 after holding for a predetermined time T2 as shown in FIG.

As described above, by holding the inner wheel brake pressure for a short time, yaw in the turning direction is generated, and the turning of the vehicle can be promoted, and the turning performance of the vehicle can be improved. . The drive braking control device for the left and right wheels for a vehicle according to the present invention is not limited to the above-described embodiment, but can be applied in various modifications such as application to the front wheels. The above-described effect can be obtained without incurring an increase or the like.

[0055]

As described above in detail, according to the drive braking control apparatus for the left and right wheels of the vehicle according to the first aspect of the present invention, the turning outer wheel side is more sufficient than the turning inner wheel side during forward acceleration turning of the vehicle. In addition to the simple, reliable and low-cost limited slip differential called the mechanical limited slip differential, the difference due to the limited slip differential can be increased without increasing the cost and weight of the equipment. The turning performance can be improved while securing the motion restriction effect.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a drive braking control device for left and right wheels for a vehicle as one embodiment of the present invention.

FIG. 2 is a flowchart (main routine) illustrating control contents of a drive braking control device for left and right wheels for a vehicle as one embodiment of the present invention.

FIG. 3 is a flowchart (turning acceleration control routine) illustrating the control contents of the vehicle left and right wheel drive braking control device as one embodiment of the present invention.

FIG. 4 is a flowchart (turning direction setting routine) for explaining the control contents of the drive braking control device for the left and right wheels for a vehicle as one embodiment of the present invention.

FIG. 5 is a flowchart (braking turning control routine) for explaining the control contents of the drive braking control device for the left and right wheels for a vehicle as one embodiment of the present invention.

FIG. 6 is a flowchart (turning direction setting and brake pressure control routine) for explaining the control content of the drive braking control device for the left and right wheels for a vehicle as one embodiment of the present invention.

FIG. 7 is a hydraulic control characteristic diagram showing brake characteristics of control during turning acceleration of the drive braking control device for the left and right wheels for a vehicle as one embodiment of the present invention.

FIG. 8 is a hydraulic control characteristic diagram showing brake characteristics of control during braking turning of the drive braking control device for the left and right wheels for a vehicle as one embodiment of the present invention.

[Explanation of symbols]

10L, 10R Drive wheels 12 Mechanical limited slip differential with one-way clutch 16 Differential limit mechanism 18 One-way clutch 20 Brake device 22 Caliper 24 Brake circuit

Claims (1)

[Claims] 1. Left and right driving wheels, a mechanical limited slip differential for transmitting a driving force output from an engine to the left and right driving wheels while limiting the differential, and a brake device provided for each of the left and right driving wheels. The limited slip differential has a one-way clutch that enables differential limiting only when the driving force input from the engine is in the forward direction. A drive braking control device for left and right wheels for a vehicle, wherein a required braking force is applied by the brake device to the drive wheel on the turning inner wheel side of the vehicle.