JP4915084B2 - Vehicle driving force distribution control device - Google Patents

Description

  The present invention relates to a vehicle driving force distribution control device, and more particularly, to a vehicle driving force distribution control device that appropriately distributes driving force to auxiliary driving wheels even during low-speed turning.

  Among vehicles, there is a so-called four-wheel drive vehicle that transmits engine driving force to front wheels and rear wheels to drive all four wheels. In such a vehicle, a driving force distribution device that distributes the driving force from the engine to the main driving wheel (front wheel) and the auxiliary driving wheel (rear wheel) via the transmission according to the traveling state of the vehicle, Some have provided a driving force distribution control device including a drive control device that drives and controls the driving force distribution device.

  When turning in such a vehicle, when the clutch of the driving force distribution device is not engaged, the differential (differential machine) absorbs the rotational difference and enables smooth turning. When the clutch is engaged, the same rotational speed is transmitted to the front differential and the rear differential. Therefore, the auxiliary drive wheel (rear wheel) rotates idly or the main drive wheel (front wheel) slips while dragging. If you can't turn.

  In situations where the tire cannot be gripped sufficiently, such as on slippery road surfaces, the tire slips easily, enabling smooth turning, but in situations where the tire can be satisfactorily gripped, such as on paved roads, the main drive wheel There is a problem that the (front wheel) is dragged while slipping and the brake is applied (tight corner braking phenomenon), the behavior of the vehicle is disturbed, and the vehicle cannot turn smoothly.

For this reason, conventionally, a driving force distribution control device for a vehicle rotates between the outer side of the main driving wheel (front wheel) where the moving distance becomes the largest when turning and the inner side of the auxiliary driving wheel (rear wheel) where the moving distance becomes the shortest. Calculate the speed difference, and if it is greater than the rotation speed difference at which the tight corner braking phenomenon begins to occur and less than the rotation speed difference at the minimum rotation radius, it is determined that the vehicle is turning and control is performed in a direction that reduces the torque transmitted to the auxiliary drive wheels. There is something to do.
Further, the vehicle driving force distribution control device controls the driving force of the main driving wheel (front wheel) according to the road surface friction coefficient so that the lower the road surface friction coefficient, the lower the road surface friction coefficient. In some cases, the driving force of the auxiliary driving wheel (rear wheel) is controlled in accordance with the road surface friction coefficient so that the driving force of the auxiliary driving wheel (rear wheel) does not exceed the driving force of the main driving wheel (front wheel).
JP-A-8-2278 JP 2002-70603 A

  By the way, in the driving force distribution control device for a vehicle disclosed in Patent Document 1, the outermost main driving wheel (front wheel) is the longest moving distance and the shortest moving distance is a condition for determining that the vehicle is turning. Since only the rotation speed inside the auxiliary drive wheel (rear wheel) is used, the auxiliary drive wheel (rear wheel) can be used even if the other main drive wheel (front wheel) inner side or auxiliary drive wheel (rear wheel) outer side is idle. Therefore, there is a disadvantage that the performance as a four-wheel drive (4WD) cannot be exhibited. Also, when turning at low speed in the four-wheel drive (4WD) state, a tight corner braking phenomenon occurs, and the behavior of the vehicle is disturbed, causing the inner side of the main driving wheel (front wheel) and the outer side of the auxiliary driving wheel (rear wheel) to idle. In addition, since it is determined that the vehicle is turning and control is performed in a direction to reduce the transmission torque to the auxiliary drive wheel (rear wheel), the idling of the wheel cannot be suppressed, and the performance as a four-wheel drive (4WD) There is an inconvenience that it cannot be fully demonstrated.

  Accordingly, an object of the present invention is to appropriately distribute the driving force to the auxiliary driving wheels even in a low-speed turn in a vehicle that distributes the driving force of the engine to the main driving wheels and the auxiliary driving wheels via the transmission. An object is to provide a driving force distribution control device for a vehicle.

The present invention relates to a driving force distribution device that distributes a driving force from an engine to main driving wheels and auxiliary driving wheels via a transmission according to a traveling state of a vehicle, and a drive control that controls the driving of the driving force distribution device. A driving force distribution control device for a vehicle comprising a device, wherein wheel speed detection means for detecting wheel speeds of the main drive wheel and the sub drive wheel is connected to the drive control device, and the drive control device comprises: Rotational speed difference calculating means for calculating a rotational speed difference between the main driving wheel and the auxiliary driving wheel, and transmission torque transmitted to the auxiliary driving wheel using the rotational speed difference calculated by the rotational speed difference calculating means. A transmission torque calculation means for calculating, a drive current calculation means for calculating a drive current value for driving the driving force distribution device according to the transmission torque calculated by the transmission torque calculation means, and a wheel speed detection means. A turning state determination means for determining whether or not the vehicle is turning based on the detected wheel speed, and a transmission torque transmitted to the auxiliary drive wheel when the turning state determination means determines that the vehicle is turning. Torque reduction means for causing the turning state determination means, the wheel speed of the main drive wheel located on the side opposite to the turning direction in order from the highest wheel speed detected by the wheel speed detection means, The wheel speed of the auxiliary driving wheel located on the opposite side to the turning direction, the wheel speed of the main driving wheel located in the same direction as the turning direction, the wheel speed of the auxiliary driving wheel located in the same direction as the turning direction, It is determined whether the vehicle is turning and not turning depending on whether or not the order is established, and the torque reduction means is more than the predetermined opening when the accelerator opening is smaller than the predetermined opening. Transmission The amount of reduction in torque is set to a large value, and the drive control device is configured such that the rotational speed difference calculated by the rotational speed difference calculating means is greater than a set rotational speed even if the vehicle is determined to be turning. Even if it is determined that the vehicle is turning, when the vehicle speed is higher than a set value, the torque reduction means is controlled not to be used, and when the transmission torque calculation means determines that the vehicle is not turning, Multiplying the front-rear difference rotational transmission torque obtained using the rotational speed difference calculated by the rotational speed difference calculating means by multiplying the transmission torque set as a characteristic for the accelerator opening and a coefficient set as a characteristic for the vehicle speed. The transmission torque for the accelerator to be obtained is added to obtain the transmission torque .

  According to the vehicle driving force distribution control device of the present invention, even when the vehicle turns at a low speed, the driving force more than necessary is not distributed to the auxiliary driving wheels, and the tight corner braking phenomenon is avoided to disturb the behavior of the vehicle. Therefore, the driving force distribution control can be performed without deteriorating the cornering performance, and the performance as a four-wheel drive (4WD) can be sufficiently exhibited.

The present invention aims to prevent the occurrence of a tight corner braking phenomenon and prevent the vehicle behavior from being disturbed even when the vehicle is turning at a low speed. When the vehicle is determined to be turning, the transmission is transmitted to the auxiliary drive wheels. This is achieved by reducing the torque.
Embodiments of the present invention will be described in detail and specifically with reference to the drawings.

  1 to 11 show an embodiment of the present invention.

  In FIG. 11, 1 is a front drive vehicle (FF vehicle) as a so-called four-wheel drive vehicle, 2 is an engine, 3 is a transmission, 4 is a front differential, 5R and 5L are right front axle, left front axle, 6R 6L is a front right wheel / left front wheel as main drive wheels, 7 is a transfer, 8 is a propeller shaft, 9 is a rear differential, 10R / 10L is a right rear axle / left rear axle, and 11R / 11L is a sub drive wheel, for example. The right rear wheel and the left rear wheel.

  The vehicle 1 is provided with a driving force distribution control device 12. This driving force distribution control device 12 applies the driving force from the engine 2 to the right front wheel, the left front wheel 6R, 6L as the main driving wheel and the right driving wheel as the auxiliary driving wheel via the transmission 3 according to the traveling state of the vehicle 1. A driving force distribution device 13 that distributes to the rear wheels / left rear wheels 11R and 11L and a drive control device 14 that controls the driving force distribution device 13 are provided.

  In the vehicle 1, the driving force of the engine 2 horizontally mounted on the front side is converted by the transmission 3 and transmitted to the front differential 4, and the right and left front wheels 6R and 6L are driven by the right and left front axles 5R and 5L. In the vehicle 1, a part of the driving force output from the transmission 3 is taken out by the transfer 7 and transmitted to the rear differential 9 through the propeller shaft 8 and the driving force distribution device 13, and the right / left rear The right and left rear wheels 11R and 11L are driven by the axles 10R and 10L.

  The driving force distribution device 13 transfers the driving force from the engine 2 to the right and left front wheels 6R and 6L as main driving wheels and the right and left rear wheels 11R and 11L as auxiliary driving wheels according to the traveling state of the vehicle 1. To distribute. The driving force distribution device 13 includes an electronically controllable clutch 15 and a coil 16 that determines the fastening force of the clutch 15, and the coil 16 is connected to the drive control device 14.

  The driving force distribution device 13 determines the fastening force of the clutch 15 by driving the coil 16 by the drive current that is a control signal from the drive control device 14, and transmits the transmission torque distributed according to the fastening force to the right and left. It is transmitted to the rear wheels 11R and 11L.

  The drive control device 14 is connected to wheel speed detecting means 17 for detecting the wheel speed of the main drive wheel and the wheel speed of the auxiliary drive wheel. The wheel speed detection means 17 is a diversion of a wheel rotation speed sensor of an anti-lock brake system (ABS) provided in a normal four-wheel drive vehicle, and includes a right front wheel rotation speed sensor 18R and a left front wheel rotation speed. The sensor 18L is composed of a right rear wheel rotational speed sensor 19R and a left rear wheel rotational speed sensor 19L. The rotational speeds of the right and left front wheels 6R and 6L and the right and left rear wheels 11R and 11L are determined as wheel speeds. To detect. As a result, the driving force distribution control device 12 eliminates the need for a new wheel speed detecting means for detecting the wheel speed of each wheel, simplifies the configuration, reduces the number of parts, and reduces the cost.

  In addition, a vehicle control device 20 is connected to the drive control device 14. The vehicle control device 20 includes at least an engine controller 21 that controls the engine 2 and a transmission controller 22 that controls the transmission 3. The engine controller 21 and the transmission controller 22 are necessary for driving and controlling the driving force distribution device 13 such as engine speed, vehicle speed, throttle opening, accelerator opening, accelerator pedal on / off, and shift speed. Various sensor information is output to the drive control device 14.

  As a result, the drive control device 14 inputs various sensors 18R / 18L, 19R / 19L, and various sensor information necessary for driving and controlling the drive force distribution device 13 from the vehicle control device 20, and the drive force distribution device. 13 is obtained, and a driving current corresponding to the fastening force is output to the coil 16 as a control signal.

  The drive control device 14 includes a central processing unit (CPU) 23 that performs various arithmetic processes, a rotational speed difference calculating unit 24, a transmission torque calculating unit 25, a driving current calculating unit 26, a turning state determining unit 27, Torque reducing means 28, a timer 29, and a memory 30 are provided.

  The rotational speed difference calculating means 24 calculates a rotational speed difference between the main drive wheel and the sub drive wheel, and is detected by the wheel speed detected by the right front wheel rotational speed sensor 18R and the left front wheel rotational speed sensor 18L. The average of the wheel speed is recognized as the front wheel rotational speed, and the average of the wheel speed detected by the right rear wheel rotational speed sensor 19R and the wheel speed detected by the left rear wheel rotational speed sensor 19L is the rear wheel rotational speed. Recognize as The slip amount in the driving force distribution device 13 is obtained as an absolute value obtained by subtracting the rear wheel rotational speed from the front wheel rotational speed.

  The transmission torque calculation means 25 calculates the transmission torque transmitted to the right and left rear wheels 11R and 11L, which are auxiliary drive wheels, using the rotation speed difference calculated by the rotation speed difference calculation means 24.

  The drive current calculation unit 26 calculates a drive current value for driving the coil 16 of the drive force distribution device 13 according to the transmission torque calculated by the transmission torque calculation unit 25. As shown in FIG. 6, this drive current value is determined based on a predetermined “transfer torque-drive current” characteristic map as shown in FIG. Is also possible.

  The turning state determination means 27 determines whether or not the vehicle 1 is turning from the wheel speed detected by the wheel speed detection means 17. This turning state determination means 27 is the wheel speed of the main drive wheel (front wheel) located on the opposite side to the turning direction in order from the highest wheel speed detected by the vehicle speed detection means 17, and then turns. The wheel speed of the auxiliary drive wheel (rear wheel) located on the opposite side of the direction, then the wheel speed of the main drive wheel (front wheel) located in the same direction as the turning direction, and finally the same position as the turning direction It is determined whether or not the order of the wheel speeds of the auxiliary drive wheels (rear wheels) to be established is established.

  The torque reduction means 28 reduces the transmission torque transmitted to the auxiliary drive wheels (rear wheels) when the turning state determination means 27 determines that the vehicle 1 is turning. When the accelerator opening is smaller than the predetermined opening, the torque reducing means 28 sets the amount of reduction in the transmission torque to a larger value than when the accelerator opening is larger than the predetermined opening. Further, even if it is determined that the vehicle 1 is turning, this torque reducing means 28 is not used when the rotational speed difference detected by the rotational speed difference calculating means 24 is larger than the set rotational speed. Furthermore, even if it is determined that the vehicle 1 is turning, the torque reducing means 28 is not used when the vehicle speed is higher than the set value.

  The timer 29 measures a predetermined time in each control.

  The memory 30 inputs and stores various information of the driving force distribution device 13.

  Connected to the drive control device 14 are a temperature detection means 31 for detecting the temperature of the drive force distribution device 13 and a mode changeover switch 32 for switching to the 2WD mode, the 4WD mode, or the like.

  In addition to the “transmission torque-driving current” characteristic map shown in FIG. 6, the drive control device 14 has a “transmission torque-vehicle speed” characteristic map 1 during normal travel shown in FIG. The map 2 of the "transmission torque-vehicle speed" characteristic at the time of turning shown in FIG. 9, the map of the "accelerator coefficient-vehicle speed" characteristic shown in FIG. 9, and the map of the "transmission torque-accelerator opening" characteristic shown in FIG. ing.

  And in this Example, in order to fully demonstrate the performance as four-wheel drive (4WD), as shown below, it is determined whether the vehicle 1 is turning.

  First, at the time of turning (for example, when turning left in FIG. 5), the wheels inside the front wheel, outside the front wheel, inside the rear wheel, and outside the rear wheel draw a locus as shown in FIG. The moving distance becomes longer in the order of the front wheel inner side, the rear wheel outer side, and the front wheel outer side. In the case where the tire is gripped, the wheel speed increases as the moving distance becomes longer. Therefore, it is possible to accurately determine whether or not the vehicle is turning by examining the magnitude relationship between the four wheel speeds.

  When the vehicle 1 determines that the vehicle is turning, the vehicle 1 is controlled so as to reduce the transmission torque transmitted to the auxiliary drive wheels. For example, the transmission torque may be obtained from the transmission torque map 1 as shown in FIG. 7 during straight running, and the transmission torque may be obtained from the transmission torque map 2 as shown in FIG. 8 during turning. Further, when the vehicle other than the outside of the main drive wheel (front wheel) where the wheel speed becomes the highest during turning, the turning determination failure condition is satisfied, so torque transmission control during turning (transfer torque in FIG. 8). Since the map 2) shifts to torque transmission control during normal driving (transmission torque map 1 in FIG. 7) and the transmission torque increases, it is possible to avoid a situation where the four-wheel drive (4WD) performance cannot be exhibited.

  However, if the outer side of the main drive wheel (front wheel) where the rotational speed is the highest during the turning of the vehicle 1 is idle, the direction of the transmission torque is reduced in order to maintain the magnitude relationship between the four wheel speeds. End up. In order to avoid this problem, if the outside of the main drive wheel (front wheel) where the wheel speed is the highest during turning is idle, the maximum rotational speed difference (maximum longitudinal difference) that occurs during turning with the tire gripped Therefore, if the difference in rotational speed is greater than the maximum rotational speed difference that occurs during turning with the tire gripped, the transmission torque will be reduced. By adding the condition that "control is not performed", even if the outer side of the main drive wheel (front wheel) where the wheel speed is the highest, the outer side of the main drive wheel idles, the torque transmitted to the auxiliary drive wheel is not controlled in the direction of decreasing, Idling can be suppressed.

  When the control is performed as described above, when any one of the wheels rotates idly during the turn, the control is performed in the direction of increasing the transmission torque transmitted to the auxiliary drive wheel, and thus the four-wheel drive (4WD) is not exhibited. You can avoid the situation.

  In the following, the three conditions of the turning determination establishment condition, the turning determination failure condition, and the transmission torque control method using the turning determination will be described in detail below.

First, when the turning determination establishment condition is described, each wheel speed is calculated from information of the vehicle speed detecting means 17 attached to the four wheels,
Right turn condition:
Rear wheel right side rotation speed <Front wheel right side rotation speed <Rear wheel left side rotation speed <Front wheel left side rotation speed Left turn condition:
It is determined whether the rear wheel left side rotational speed <the front wheel left side rotational speed <the rear wheel right side rotational speed <the front wheel right side rotational speed is satisfied. If either the right turn condition or the left turn condition is satisfied, it is assumed that the car is turning.

Next, the turning determination failure condition will be described.
When the right turn condition is no longer satisfied from the condition that the right turn condition has been determined,
When the left turn condition is no longer met from the condition that the left turn condition has been determined,
When there is a rotation speed difference that exceeds the limit value of the rotation speed difference that is generated during turning without any wheels spinning idle,
It is.

In addition, in the turning determination failure condition, the following items (1) to (3) can be taken into consideration.
(1) Due to the unevenness of the road surface, it may be erroneously determined that the vehicle is turning even though the vehicle is traveling straight ahead. As described above, the time condition is added to the turning determination establishment condition. Also, since the tire may stop in a very short time due to the depression or depression of the accelerator pedal or during braking, a time condition is also added to the turning determination failure condition. In this way, by adding the time condition, it is possible to avoid erroneous determination between straight traveling and turning.
(2) Since the tight corner braking phenomenon occurs and the vehicle behavior is disturbed only in the low vehicle speed range, the turning judgment is performed and the control for reducing the transmission torque is performed when the vehicle speed is a predetermined value or less. The vehicle speed condition to be added is added. As described above, by adding the vehicle speed condition, it is possible to perform control for reducing the transmission torque only when necessary, and to eliminate useless control.
(3) Under the above-mentioned right turn condition and left turn condition, it is erroneously determined even if a tire has a slightly different degree of diameter (about 1 to 3%), and control for reducing torque during turning is performed. Although there is no difference in diameter, in order to accurately determine whether or not the vehicle is turning, a value obtained by multiplying each wheel speed by a coefficient can be used as follows.
Right turn condition:
Coefficient 1 * Rear wheel right side rotational speed <Coefficient 2 * Front wheel right side rotational speed <Coefficient 3 * Rear wheel left side rotational speed <Coefficient 4 * Front wheel left side rotational speed Left turning condition:
Coefficient 5 * Rear wheel left side rotational speed <Coefficient 6 * Front wheel left side rotational speed <Coefficient 7 * Rear wheel right side rotational speed <Coefficient 8 * Front wheel right side rotational speed The above coefficients 1 to 8 are arbitrary values.
Thus, by using a coefficient for each wheel rotation speed, it is possible to accurately determine the turning.

And the calculation method of the transmission torque using turning determination is divided and described in the following cases (1) to (4).
(1) When it is determined that the vehicle is not turning, the transmission torque is obtained as follows.
A value obtained by adding the accelerator transmission torque determined according to the accelerator opening and the front-rear differential rotation transmission torque determined according to the vehicle speed and the front-rear differential rotation (ΔN: rotational speed difference) is defined as the transmission torque.
For example, the transmission torque corresponding to the accelerator opening is obtained by applying the accelerator speed obtained by applying the vehicle speed to the “accelerator coefficient-vehicle speed” characteristic of FIG. 9 and the accelerator opening, and the “transmission torque-accelerator opening” characteristic of FIG. It is obtained as a value multiplied by the transmission torque obtained by applying to. The transmission torque for the front-rear differential rotation is obtained by applying the vehicle speed and the front-rear differential rotation (ΔN: rotational speed difference) to a transmission torque map as shown in FIG.
(2) When it is determined that the vehicle is turning and the accelerator is on, a torque obtained by reducing a certain ratio from the transmission torque obtained by the same method as in (1) above is used as the transmission torque.
For example, as shown in FIG. 8, the transmission torque for the forward / backward differential rotation is changed from the transmission torque map of FIG. 7 to a transmission torque map in which the torque in the region where the tight corner braking phenomenon is likely to occur is reduced in advance. The transmission torque may be obtained by applying (ΔN: rotational speed difference).
(3) When it is determined that the vehicle is turning and the accelerator is off, a torque obtained by reducing a certain ratio from the transmission torque obtained by the same method as in (1) above is used as the transmission torque. However, the rate of reduction is made larger than in the case of (2) above.
For example, the front-rear differential rotation transmission torque may be a value obtained by reducing the transmission torque obtained in (2) above by a certain percentage.
(4) When it is determined that the vehicle is not turning, and the accelerator is off and the engine speed is lower than the predetermined value, torque obtained by reducing a certain ratio from the transmission torque obtained by the same method as in (1) above. The transmission torque. However, the rate of reduction is made larger than in the case of (2) above. For example, the front-rear differential rotation transmission torque may be a value obtained by reducing the transmission torque obtained in (2) above by a certain percentage.

  Next, the operation of this embodiment will be described based on a flowchart.

  As shown in the flowchart of FIG. 1, when the program starts (step A01), first, various information (engine speed, vehicle speed, throttle opening, accelerator opening, accelerator pedal, etc.) from various sensors attached to the vehicle 1 is set. ON / OFF, shift speed, etc.) are obtained and the vehicle speed, rotational speed difference, and rotational speed of each wheel are calculated and obtained (step A02).

And as judgment 1, from the magnitude relation of four wheel speeds, that is,
It is determined whether or not the vehicle 1 is turning right based on the relationship of rear wheel right side rotational speed <front wheel right side rotational speed <rear wheel left side rotational speed <front wheel left side rotational speed (step A03).

  If this step A03 is YES, the right turn determination counter is incremented and the right turn failure counter is cleared to zero (0) (step A04). On the other hand, if step A03 is NO, the right turn determination counter is cleared to zero (0) and the right turn failure counter is incremented (step A05).

  After the process of step A04 and after the process of step A05, as determination 2, it is determined whether or not the vehicle speed exceeds a predetermined vehicle speed (step A06).

  If this step A06 is YES, the right turn determination counter is cleared to zero (0) (step A07).

  On the other hand, if step A06 is NO, it is determined as determination 3 whether the right turn determination counter has passed a predetermined time (step A08). If this step A08 is YES, the right turn The turn flag is set to 1 (step A09).

  After the process of step A07, after the process of step A09, and when the step A08 is NO, it is determined as determination 4 whether the right turn failure counter has passed a predetermined time (step A10). ).

  If this step A10 is YES, the right turn flag is set to zero (0) (step A11), and the process proceeds to the flowchart of FIG. On the other hand, if step A10 is NO, no processing is performed and the process immediately proceeds to the flowchart of FIG.

In the flowchart of FIG. 2, first, as a determination 5, it is determined whether or not the vehicle is making a left turn from the relationship between the four wheel speeds, that is,
The rear wheel left side rotational speed <the front wheel left side rotational speed <the rear wheel right side rotational speed <the front wheel right side rotational speed is judged (step A12).

  If this step A12 is YES, the left turn determination counter is incremented, and the left turn failure counter is cleared to zero (0) (step A13). On the other hand, when the step A12 is NO, the left turn determination counter is cleared to zero (0) and the left turn failure counter is incremented (step A14).

  After the process of step A13 and after the process of step A14, it is determined as determination 6 whether or not the vehicle speed is higher than a predetermined vehicle speed (step A15).

  If this step A15 is YES, the left turn determination counter is cleared to zero (0) (step A16).

  On the other hand, when this step A15 is NO, it is determined as a decision 7 whether or not the left turn determination counter has passed a predetermined time (step A17), and when this step A17 is YES, a left turn flag Is set to 1 (step A18).

  After the process of step A16, after the process of step A18, and when the step A17 is NO, it is determined as determination 8 whether the left turn failure counter has passed a predetermined time (step A19). .

  If this step A19 is YES, the left turn flag is set to zero (0) (step A20), and the process proceeds to the flowchart of FIG. On the other hand, if step A19 is NO, no processing is performed and the process immediately proceeds to the flowchart of FIG.

  In the flowchart of FIG. 3, first, as a determination 9, it is determined whether the right turn flag is 1 or the left turn flag is 1 (step A21).

  When this step A21 is YES, the turning determination flag is set to 1 (step A22), and as the determination 10, the right turning flag is 0 and the left turning flag is 0, or the rotational speed difference is the maximum rotational speed difference during turning. It is judged whether or not it has become larger (step A23). On the other hand, when the step A21 is NO, no processing is performed, and immediately, as a determination 10, the right turn flag is 0 and the left turn flag is 0, or the rotational speed difference is the maximum rotational speed difference during turning. It is judged whether or not it has become larger (step A23).

  If step A23 is YES, the turning flag is set to zero (0) (step A24), and it is determined as determination 11 whether the determination flag is 1 (step A25). On the other hand, if step A23 is NO, nothing is done, and it is immediately determined as determination 11 whether the determination flag is 1 (step A25).

  If this step A25 is NO, it is judged as a decision 12 whether or not the accelerator opening is smaller than a predetermined value (step A26). If this step A26 is YES, a decision 13 is made as the engine speed. It is determined whether or not the speed is smaller than a predetermined value (step A27).

  On the other hand, when the said step A25 is YES, it is judged as judgment 14 whether the accelerator opening became smaller than the predetermined value (step A28).

  When the step A27 is YES and when the step A28 is YES, the process proceeds to the flowchart of FIG. 4, and the transmission torque obtained from the low-value transmission torque map (FIG. 8) is further increased by a certain ratio. The reduced value is set as the transmission torque (step A29).

  Further, when step A27 is NO and when step A28 is NO, the process proceeds to the flowchart of FIG. 4 and the value obtained from the low-value torque map (FIG. 8) is used as the transmission torque ( Step A30).

  Furthermore, when the said step A26 is NO, it transfers to the flowchart of FIG. 4, and uses the value calculated | required from the torque map (FIG. 7) of a high value as a transmission torque (step A31).

After the processing of Step A29 to Step A31, the calculated transmission torque is applied to the “transmission torque-drive current” characteristic of FIG. 6 to calculate the final drive current value (Step A32). This driving current value is output to the driving force distribution device 13 (step A33), and the program is ended (step A34).
It should be noted that all the counters described above do not overflow.

  1 to 4 may be executed and processed repeatedly by the central processing means (CPU) 23 at predetermined intervals.

  In other words, in this embodiment, when the four wheel speeds satisfy the conditions of right turn and left turn, that is, in the right turn, the conditions of the right rear wheel <the right front wheel <the left rear wheel <the left rear wheel <the left front wheel are satisfied. In the left turn, when the condition of the rear left wheel <the front left wheel <the rear right wheel <the front right wheel is satisfied, it is determined that the vehicle is turning, and the transmission torque reduction control is performed. However, torque reduction control during turning is not performed when a rotational speed difference (front / rear differential rotation) greater than the maximum rotational speed difference (maximum front / rear differential rotation) generated during turning occurs while the tire is gripped. This prevents the tight corner braking phenomenon and avoids the disturbance of the vehicle behavior. Further, since only the information of the wheel speed detection means 17 for ABS is required, the number of parts is reduced, the configuration is simple, and the price is low. When any one of the wheels idles, the process shifts to control for increasing the transmission torque, thereby avoiding a situation where the four-wheel drive (4WD) performance cannot be exhibited.

  In addition, when using the rotational speed obtained by multiplying each coefficient in each of the above relational expressions, it is possible to accurately determine that the vehicle is turning even if the tires have different diameter differences, thereby increasing the determination accuracy. be able to.

  Further, when it is determined that the vehicle is turning and the accelerator is on, the torque transmitted to the auxiliary drive wheel is reduced, and when it is determined that the vehicle is turning and the accelerator is off, the torque is further reduced. In addition, since unnecessary torque transmission is reduced and heat generation in the clutch 15 is reduced, deterioration is prevented and fuel consumption is improved.

  Furthermore, when it is determined that the vehicle is not turning, the accelerator is off, and the engine rotational speed is equal to or less than a predetermined value, the torque can be further reduced to prevent the behavior of the vehicle from being disturbed.

  As a result, it is determined whether or not the vehicle 1 is turning based on the wheel speed, and when the vehicle 1 is determined to be turning, the transmission torque transmitted to the auxiliary drive wheel is reduced to be necessary at the time of low speed turning. Since no driving force is distributed to the auxiliary driving wheels, the tight corner braking phenomenon does not occur and the behavior of the vehicle is not disturbed, so that the driving force distribution control is performed without deteriorating the cornering performance. Is possible.

  Further, the turning state determination means 27 is, in order from the highest wheel speed detected by the vehicle speed detection means 17, the wheel speed of the main drive wheel located on the side opposite to the turning direction, and then the turning direction. Is the wheel speed of the auxiliary driving wheel located on the opposite side, then the wheel speed of the main driving wheel located in the same direction as the turning direction, and finally the wheel speed of the auxiliary driving wheel located in the same direction as the turning direction. It is determined whether or not the order is established. Thereby, since the magnitude relationship between the wheel speeds of the four wheels is determined, it is possible to realize highly accurate driving force distribution control.

  Furthermore, when the accelerator opening is smaller than the predetermined opening, the torque reducing means 28 sets the amount of reduction in the transmission torque to a larger value than when the accelerator opening is larger than the predetermined opening. Thereby, since the transmission torque amount is changed according to the accelerator opening amount, the driving current is not output more than necessary, thereby reducing the heat generation amount of the driving force distribution device 13 and fuel consumption. The amount can be reduced.

  Furthermore, even if it is determined that the vehicle 1 is turning, the torque reducing means 28 is not used when the rotational speed difference calculated by the rotational speed difference calculating means 24 is larger than the set rotational speed. As a result, when any one of the four wheels is idling, normal transmission torque control is performed, so that the advantages of the four-wheel drive (4WD) system can be fully utilized. it can.

  Further, even if it is determined that the vehicle 1 is turning, the torque reduction means 28 is not used when the vehicle speed is higher than the set value. As a result, the amount of transmission torque is changed according to the vehicle speed, so that the amount of driving force distribution is not reduced more than necessary, and thus driving force distribution control can be performed without deteriorating cornering performance. Is possible.

  Therefore, in the vehicle 1 that distributes the driving force of the engine 2 to the main driving wheel and the auxiliary driving wheel via the transmission 3, the purpose of appropriately distributing the driving force to the auxiliary driving wheel is achieved even during low-speed turning. can do.

  Even when the vehicle is turning at a low speed, it is possible to apply a vehicle other than the four-wheel drive vehicle to prevent the driving force more than necessary from being distributed to the auxiliary drive wheels and to avoid the occurrence of the tight corner braking phenomenon.

It is a flowchart of driving force distribution control. It is a flowchart of the driving force distribution control following FIG. FIG. 3 is a flowchart of driving force distribution control following FIG. 2. FIG. It is a flowchart of the driving force distribution control following FIG. It is a figure which shows the locus | trajectory of each wheel at the time of turning (left turning). It is a figure which shows the map of the "transfer torque-drive current" characteristic. It is a figure which shows the map 1 of the "transmission torque-vehicle speed" characteristic at the time of normal driving | running | working. It is a figure which shows the map 2 of the "transmission torque-vehicle speed" characteristic at the time of turning. It is a figure which shows the map of an "accelerator coefficient-vehicle speed" characteristic. It is a figure which shows the map of the "transfer torque-accelerator opening" characteristic. It is a system block diagram of a driving force distribution control device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vehicle 2 Engine 3 Transmission 12 Driving force distribution control device 13 Driving force distribution device 14 Drive control device 17 Wheel speed detection means 18R Right front wheel rotational speed sensor 18L Left front wheel rotational speed sensor 19R Right rear wheel rotational speed sensor 19L Left rear wheel Rotational speed sensor 20 Vehicle control device 24 Rotational speed difference calculating means 25 Transfer torque calculating means 26 Drive current calculating means 27 Turning state calculating means 28 Torque reducing means

Claims (1)

A driving force distribution device that distributes the driving force from the engine to the main driving wheel and the sub driving wheel via the transmission according to the traveling state of the vehicle, and a drive control device that drives and controls the driving force distribution device. In the driving force distribution control device for a vehicle, wheel speed detection means for detecting wheel speeds of the main driving wheel and the auxiliary driving wheel is provided connected to the driving control device, and the driving control device includes the main driving wheel. A rotational speed difference calculating means for calculating a rotational speed difference between the auxiliary driving wheel and a transmission torque for calculating a transmission torque transmitted to the auxiliary driving wheel using the rotational speed difference calculated by the rotational speed difference calculating means. Detected by a calculation means, a drive current calculation means for calculating a drive current value for driving the driving force distribution device according to the transmission torque calculated by the transmission torque calculation means, and the wheel speed detection means A turning state determining means for determining whether or not the vehicle is turning based on a wheel speed, and a torque reduction for reducing a transmission torque transmitted to the auxiliary drive wheel when the turning state determining means determines that the vehicle is turning. The turning state determination means includes, in order from the highest wheel speed detected by the wheel speed detection means, the wheel speed of the main drive wheel located on the side opposite to the turning direction, the turning direction, and Is the wheel speed of the auxiliary driving wheel located on the opposite side, the wheel speed of the main driving wheel located in the same direction as the turning direction, and the wheel speed of the auxiliary driving wheel located in the same direction as the turning direction. Whether the vehicle is turning or not is determined based on whether the vehicle is turning, and when the accelerator opening is smaller than the predetermined opening, the torque reduction means Reduction Is set to a large value, and the drive control device determines that the rotation speed difference calculated by the rotation speed difference calculation means is larger than the set rotation speed even when it is determined that the vehicle is turning, and the vehicle turns. When the vehicle speed is larger than a set value even if it is determined that the vehicle is in the middle, control is performed so that the torque reduction means is not used, and when the transmission torque calculation means determines that the vehicle is not turning, the difference in rotational speed is determined. Acceleration transmission determined by multiplying the transmission torque set as the characteristic with respect to the accelerator opening and the coefficient set as the characteristic with respect to the vehicle speed to the forward / backward differential rotation transmission torque calculated using the rotational speed difference calculated by the calculation means A driving force distribution control device for a vehicle, wherein torque is added to obtain the transmission torque .

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