JP4525344B2 - Vehicle attitude control device - Google Patents

Description

  The present invention relates to a vehicle attitude control device, and more particularly to attitude control of a vehicle in which steered wheels are drive wheels.

Conventionally, a technique described in Patent Document 1 is known as a vehicle attitude control device. This publication discloses a technique for setting a delay time until the driving force is generated and limiting the driving force based on the steering angle and the accelerator opening when the front-wheel-drive vehicle starts. This prevents the occurrence of suspension judder that occurs when the vehicle traveling vector and the driving vector of the driving wheel (steering wheel) are different.
JP 2001-90568 A

  In recent years, as front-wheel drive vehicles have become larger and higher in driving force, the applicant has accelerated the vehicle while turning the vehicle, and if excessive driving force is input to the steered wheels, the steering angle of the steered wheels is increased. It has been found that a phenomenon that increases against the driver's intention (hereinafter referred to as torque steer) occurs. That is, when the vehicle is turning, the driving torque of the outer turning wheel is larger than the driving torque of the inner turning wheel based on the load movement of the vehicle, and torque steer is generated due to this driving torque difference. When suppressing this torque steer, the above-described conventional technology that suppresses suspension judder that occurs when the vehicle starts is controlled simply based on the steering angle of the steering wheel, taking into account load movement and the difference in driving force between the left and right steering wheels. There is a problem that torque steer cannot be suppressed.

  The present invention has been made paying attention to the above problem, and an object of the present invention is to provide a vehicle attitude control device capable of suppressing torque steer during turning acceleration in a vehicle that drives steered wheels.

  In order to achieve the above object, according to the present invention, in a vehicle attitude control device including a steered wheel driven by a drive source, the vehicle is turning, and the turning outer wheel side is more than the steered wheel driving torque on the turning inner wheel side. Based on the turning state detected by the turning state detecting means and the turning state detected by the turning state detecting means, and the steering wheel driving torque on the turning inner wheel side and the steering wheel driving torque on the turning outer wheel side. Torque upper limit value setting means for setting the drive torque upper limit value of the drive source, and the steering within a range equal to or less than the upper limit value set by the torque upper limit value setting means so that the difference from the direction wheel drive torque is reduced. Driving force control means for controlling the driving force of the wheel.

It is possible to suppress the driving torque difference of the right and left steering wheels during vehicle turning (especially state in which the drive torque of the turning outer wheel is larger than the driving torque of the inner wheel), it is possible to avoid the door Rukusutea.

  Hereinafter, the best mode for realizing the vehicle attitude control device of the present invention will be described based on Example 1 shown in the drawings.

  FIG. 1 is a schematic diagram illustrating the configuration of the vehicle attitude control device according to the first embodiment. The vehicle of the first embodiment is a front-wheel drive vehicle in which the engine 1 is disposed in front of the vehicle and drives the front wheels 5FL and 5FR serving as steered wheels. The drive torque output from the engine 1 is shifted by the automatic transmission 2 and is connected to the right first drive shaft SR1 and the left first drive via a differential 2a (see FIG. 2) housed in the automatic transmission 2. Output to drive shaft SL1. The first drive shafts SL1 and SR1 are output to the second drive shafts SL2 and SR2 via the universal joint UJ provided on the kingpin shaft, and drive the left and right front wheels 5FL and 5FR.

  A rack and pinion mechanism 4 is connected to the steering wheel 3 via a steering shaft, an intermediate shaft, a pinion shaft, and the like. When the driver operates the steering wheel 3, the axle 43 is rotated around the king pin KP via the rack shaft 41 and the tie rod 42, and the front wheels 5FL and 5FR are steered.

  The engine control unit 20 (hereinafter referred to as ECU) controls the driving state of the engine 1 based on various sensor values and a command signal from the control unit 10 described later. The automatic transmission control unit 30 (hereinafter referred to as ATCU) controls the gear ratio of the automatic transmission 2 according to the traveling state of the vehicle based on various sensor values and command signals from the control unit 10 described later.

  The control unit 10 includes a rotational speed of each wheel 5FL, 5FR, 5RL, 5RR detected by the wheel speed sensor 11, a vehicle yaw rate detected by the yaw rate sensor 12, and a vehicle acceleration detected by the lateral acceleration sensor 13. The lateral acceleration, the driver's steering angle detected by the steering angle sensor 14, the driver's accelerator pedal depression amount detected by the accelerator pedal stroke sensor 15 (hereinafter referred to as APS), and the like are input. The control unit 10 performs torque steer avoidance control processing based on various sensor values, and outputs control signals to the ECU 20 and the ATCU 30.

  FIG. 2 is a control block diagram showing the configuration of the control unit 10. In the control unit 10, a driving torque calculation unit 10 a that estimates and calculates the engine driving torque after a predetermined time based on the accelerator pedal stroke of the driver, and a torque upper value setting unit that sets the driving torque upper limit value Pmax of the engine 1. 10b and a driving force control unit 10c that outputs a driving force control command to the ECU 10 based on the set torque upper limit value, and a road surface μ that estimates a road surface friction coefficient during traveling (hereinafter referred to as a road surface μ). It is comprised from the estimation part 10d.

FIG. 3 is a flowchart showing torque steer avoidance control processing in the control unit 10.
In step 101, the road surface μ estimation unit 10d executes road surface μ estimation processing. Details will be described later.
In step 102, it is determined whether or not the vehicle is turning based on the sensor value from the lateral acceleration sensor 13. If the vehicle is not turning, the present control flow is terminated. If the vehicle is turning, the process proceeds to step 103.
In step 103, the drive torque P * is calculated. Here, the driving torque P * represents a value that estimates how much driving force is output from the engine 1 after a predetermined time by the driver's accelerator pedal operation.
In step 104, based on the lateral acceleration detected by the lateral acceleration sensor 13, the driving force upper limit value Pmax is set from the upper limit value map.
In step 105, it is determined whether or not the driving torque P * is larger than the driving force upper limit value Pmax. If larger, the process proceeds to step 106, and otherwise, the process proceeds to step 107.
In step 106, the driving force upper limit value Pmax is output as the driving force command value.
In step 107, the drive torque P * is output as the drive force command value.

FIG. 4 is a flowchart showing the road surface μ estimation process.
In step 201, it is determined whether or not the driving torque is a preset first driving torque value a1. If a1, the process proceeds to step 202. Otherwise, the process proceeds to step 209.
In step 202, a reference time To is set.
In step 203, the timer τ starts counting up.
In step 204, at least one of the front wheels 5FL and 5FR which are steered wheels has slipped based on the wheel speed difference between the front wheels 5FL and 5FR and the rear wheels 5RR and 5RL detected by the wheel speed sensor 11. If slip occurs, the process proceeds to step 206. Otherwise, the process proceeds to step 205.
In step 205, the timer τ is counted up.
In step 206, it is determined whether or not the reference time To is larger than the timer value τ. If so, the process proceeds to step 207. Otherwise, the process proceeds to step 208.
In step 207, the road surface friction coefficient is corrected to decrease (initial value: μ = 1).
In step 208, the road surface friction coefficient is corrected by increasing (initial value: μ = 1).
In step 209, the road surface friction coefficient is set to μ = 1.

[Operation of torque steer avoidance control]
Next, the operation of the torque steer avoidance control will be described. First, the road surface μ estimation process will be described.

(Operation of road surface μ estimation process)
In the first embodiment, the road surface μ estimation is executed when the driving torque of the engine 1 reaches the first driving torque value a1. FIG. 5 is a diagram illustrating the relationship between the driving torque and the slip time. When the road surface μ is set to μ = 1, the first drive torque value a1 is the reference time To when the steered wheel slip occurs when the drive torque value a1 is output on the road surface μ. Value.

  Therefore, the timer τ counts the slip time from when the drive torque reaches the first drive torque value a1 until the actual slip occurs. When the slip time is longer than the reference time To, the road surface μ is estimated to be high, and when the slip time is shorter than the reference time To, the road surface μ is estimated to be low. Now, if the road surface μ is corrected to decrease from μ = 1, it is corrected to μ = 0.6. At this time, the first drive torque value a1 is replaced with a value a2 corresponding to μ = 0.6. Next, the reference time To is replaced with a time T1 corresponding to μ = 0.6. Then, the slip time is measured from when the drive torque reaches the first drive torque a2, and if the slip time is shorter than T1, the road surface μ is further reduced and corrected, and if the slip time is approximately near T1, Set μ = 0.6. As described above, the road surface μ can be accurately estimated based on the first driving torque value and the reference time corresponding to the road surface μ.

(Torque steer generation logic)
Next, the logic for generating torque steer during turning acceleration will be described. FIG. 6 is a diagram illustrating the relationship between the front wheels 5FL and 5FR and the differential 2a. FIG. 6A is a diagram showing the relationship between the wheel load and the drive torque when traveling straight. During straight running, the wheel loads acting on the front wheels 5FL and 5FR are equal, and the drive torques TR and TL output from the differential 2a to the first drive shafts SR1 and SL1 are also equal.

  FIG. 6B is a diagram showing the relationship between wheel load and driving torque at the start of turning. When the driver steers the steering wheel 3, the front wheels 5FL and 5FR are steered. At this time, the wheel load has not moved so much, and the rolling resistance of the left front wheel 5FL corresponding to the turning inner wheel increases compared to the rolling resistance of the right front wheel 5FR corresponding to the turning outer wheel due to the magnitude relationship of the turning radius. Therefore, the drive torque TL of the left first drive shaft SL1 is larger than the drive torque TR of the right first drive shaft SR1.

  FIG. 6C is a diagram showing the relationship between wheel load and driving torque during turning. During turning, the vehicle generates lateral acceleration, and the center of gravity of the vehicle tilts with the roll of the vehicle body. As a result, the wheel load of the right front wheel 5FR that is the outer turning wheel increases, and the wheel load of the left front wheel 5FL that is the inner turning wheel decreases. This reduction in the wheel load of the turning inner wheel causes a reduction in driving torque that can be transmitted to the road surface by the left front wheel 5FL that is the turning inner wheel. If the driver depresses the accelerator pedal in this state and indicates the intention to accelerate, the driving torque output from the engine 1 increases and the left front wheel 5FL slips. Hereinafter, the drive torque of the left and right first drive shafts SR1 and SR2 due to this slip will be described.

  FIG. 7 is a diagram showing the mechanical configuration of the differential 2a and the relationship between the drive torque Tin output from the engine 1 when the left front wheel 5FL slips and the drive torques TR and TL of the first drive shafts SR1 and SL1. The differential 2a includes a side gear SG connected to the left and right first drive shafts SL1 and SR1, a pinion mate PM meshing with both side gears SG, and a washer WS provided between the side gear SG and the pinion mate PM and the casing. Has been.

  When the left first drive shaft SL1 idles, the rotation number of the right first drive shaft SR1 is decreased by the number of rotations increased by the idle rotation. At this time, even if the drive torque Tin input from the engine 1 is to be evenly distributed to the left and right drive shafts, the rotational speed increased by idling is consumed by the frictional energy between the washer WS, the pinion mate PM, and the side gear SG. . As a result, the left driving torque TL that becomes the turning inner wheel decreases, and the right driving torque TR that becomes the turning outer wheel increases. Hereinafter, this phenomenon is defined as torque reverse.

  This torque reverse increases the driving torque of the outer turning wheel and decreases the driving torque of the inner turning wheel. Due to the difference between the left and right drive torques, a rotational moment corresponding to the kingpin offset is generated around the kingpin axis, and torque steer in which the front wheels 5FL and 5FR are further wound in the turning direction is generated. At this time, the driving torque upper limit value Pmax capable of preventing the occurrence of this torque reverse can be calculated from various vehicle specifications and experiments from the lateral acceleration generated in the vehicle and the road surface μ.

  FIG. 8 is a diagram illustrating a relationship among the lateral acceleration, the road surface μ, and the driving torque upper limit value Pmax. At a certain lateral acceleration and road surface μ, a driving torque upper limit value is set such that the turning inner wheel causes slipping and the first drive shaft driving torque on the turning inner wheel side does not become larger than the first driving shaft driving torque of the turning outer wheel due to torque reverse. Is set. Therefore, when the driving torque P * of the engine 1 estimated based on the driver's accelerator pedal operation is larger than the driving torque upper limit value Pmax, the generation of driving torque larger than the driving torque upper limit value Pmax is suppressed. Thereby, torque steer during turning acceleration can be avoided reliably.

  As described above, the vehicle attitude control device according to the first embodiment has the following effects.

  (1) Whether the steering wheel driving torque on the outer turning wheel side is larger than the steering wheel driving torque on the inner turning wheel side (that is, whether or not torque reverse has occurred). The drive torque upper limit value Pmax of the engine 1 that is the drive source is set so that the difference between the steered wheel drive torque on the turning inner wheel side and the steered wheel drive torque on the turning outer wheel side is reduced. By controlling the driving force of the engine 1 within the range of the driving torque upper limit value Pmax or less, torque steer can be reliably avoided even if acceleration is performed during turning.

  (2) By detecting the lateral acceleration of the vehicle and setting the drive torque upper limit value Pmax based on this lateral acceleration, even if an acceleration request is made during a turn, torque steer can be avoided reliably. it can.

  (3). The road surface friction coefficient μ was estimated, and the lower upper limit value was set as the road surface friction coefficient μ was lower. Therefore, torque steer can be reliably avoided according to the road surface condition.

  (4) When estimating the road surface friction coefficient μ, the steering wheel driving slip at the set first steering wheel driving torque a1 is generated based on the preset initial road surface friction coefficient μ = 1. A reference time To is set. Next, the slip time from when the first steered wheel drive torque a1 is reached until the drive slip of the front wheels 5FL, 5FR occurs is measured. Next, the reference time To and the slip time are compared, and when the slip time is shorter than the reference time To, the road surface friction coefficient is updated to be smaller than the initial road surface friction coefficient, and when the slip time is longer than the reference time To, the initial time is updated. Update to a road surface friction coefficient greater than the road surface friction coefficient. As described above, the road surface friction coefficient can be accurately estimated by correcting the road surface μ based on the time until the drive slip occurs at a certain drive torque.

  Next, Example 2 will be described. Since the basic configuration is the same as that of the first embodiment, only different points will be described. In Example 1, attention was paid to the fact that torque steer is generated by the occurrence of torque reverse. On the other hand, the second embodiment focuses on the point that the torque transmission efficiency changes due to the change in the joint angle of the universal joint accompanying the load movement during turning. In the second embodiment, as shown in FIG. 9, stroke sensors 16FL and 16FR for detecting the suspension strokes of the right and left suspensions SPR and SPL that support the front wheels 5FL and 5FR are provided.

  FIG. 9 is a diagram showing the relationship between the front wheels 5FL and 5FR, the first drive shafts SR1 and SL1, and the second drive shafts SR2 and SL2 when turning left. When load movement occurs during turning, the vehicle body rolls around the center of gravity G1 of the vehicle. With this roll behavior, the left suspension SPL extends and the right suspension SPR contracts. Further, in the right front wheel 5FR which is a turning outer wheel, the joint angle θout between the right first drive shaft SR1 and the right second drive shaft SR2 is larger than that during straight traveling. On the other hand, in the left front wheel 5FL which is a turning inner wheel, the joint angle θin between the left first drive shaft SL1 and the left second drive shaft SL2 becomes small.

  As the joint angle θ increases, the torque transmission efficiency improves, and as the joint angle θ decreases, the torque transmission efficiency decreases. Therefore, when turning, there is a possibility that a difference in right and left occurs in the driving torque transmitted to the left and right front wheels 5FL and 5FR, and torque steer may occur. Therefore, in the second embodiment, the left and right suspension strokes are detected, and control for avoiding torque steer due to the change in the joint angle θ is performed based on the difference between the left and right suspension strokes.

FIG. 10 is a flowchart illustrating torque steer avoidance control according to the second embodiment.
In step 301, road surface μ estimation processing is executed. Since the basic estimation process is the same as that of the first embodiment, description thereof is omitted.
In step 302, it is determined whether or not there is a certain difference between the load changes, that is, the left and right suspension strokes q1 and q2, and if there is a difference, it is determined that there is a load change and the process proceeds to step 303. This control flow ends.
In step 303, the drive torque P * is calculated. Here, the driving torque P * represents a value that estimates how much driving force is output from the engine 1 by the driver's accelerator pedal operation.
In step 304, based on the absolute value of the difference between the left and right suspension strokes (q1−q2) detected by the suspension stroke sensor 16, the driving force upper limit value Pmax is set from the upper limit value map shown in FIG.
In step 305, it is determined whether or not the driving torque P * is larger than the driving force upper limit value Pmax. If it is larger, the process proceeds to step 306. Otherwise, the process proceeds to step 307.
In step 306, the driving force upper limit value Pmax is output as the driving force command value.
In step 307, steered wheel drive torque P * is output as a drive force command value.

[Operation of torque steer avoidance control]
The operation of the torque steer avoidance control according to the second embodiment will be described. If the absolute value of the suspension stroke difference (q1-q2) is determined to be greater than a certain value, it can be estimated that a load change has occurred. If a left-right difference occurs in the joint angle θ of the universal joint UJ with this load movement, a left-right difference occurs in the driving torque of the front wheels 5FL, 5FR, causing torque steer. This torque steer becomes more prominent as the left / right difference increases. In the second embodiment, the drive torque upper limit value Pmax is set according to the difference between the left and right torque steer.

  FIG. 11 is a diagram illustrating the relationship among the suspension stroke difference, the road surface μ, and the drive torque upper limit value Pmax. The drive torque upper limit value at which a difference between the first drive shaft drive torque on the inner turning wheel side and the first drive shaft drive torque on the outer turning wheel does not increase due to a change in torque transmission efficiency at a certain suspension stroke difference and road surface μ. Is set. Therefore, when the driving torque P * of the engine 1 estimated based on the driver's accelerator pedal operation is larger than the driving torque upper limit value Pmax, the generation of driving torque larger than the driving torque upper limit value Pmax is suppressed. Accordingly, further acceleration during vehicle turning can suppress further increase in the suspension stroke difference, and torque steer during turning acceleration can be avoided reliably.

  As described above, the vehicle attitude control device according to the second embodiment has the following effects in addition to the functions and effects described in the first embodiment.

  (5) The change in steering wheel load on the turning inner wheel side during vehicle turning is detected, and the difference between the steering wheel driving torque on the turning inner wheel side and the steering wheel driving torque on the turning outer wheel side is reduced. A drive torque upper limit value Pmax of 1 is set. And the driving force of the engine 1 was controlled in the range below the set upper limit. Therefore, even if an acceleration request is made during turning, torque steer can be reliably avoided.

  (6). Load change was detected based on the suspension stroke. As a result, it is possible to perform control based on a value directly related to the joint angle, and it is possible to accurately avoid torque steer.

  Next, Example 3 will be described. In the first and second embodiments, the torque upper limit value is set during turning. On the other hand, the third embodiment is different in that the control start threshold value of a traction control system (hereinafter referred to as TCS) preset in the vehicle is changed.

  In the TCS control, the slip ratio is calculated based on the rotational speed difference between the front wheels 5FL and 5FR that are drive wheels and the rear wheels 5RR and 5RL that are driven wheels. FIG. 13 is a diagram showing the relationship between the slip ratio and the torque that can be transmitted from the front wheels 5FL and 5FR to the road surface. Since the transmittable torque decreases as the slip ratio increases, a normal threshold that can obtain the maximum value of the transmittable torque is set in normal TCS control. When the slip ratio exceeds the normal threshold, the driving torque is suppressed, and the slip ratio is controlled to be smaller than the normal threshold.

  In the third embodiment, torque steer avoidance control is performed using the configuration of the TCS control. In the third embodiment, a drive torque upper limit value Pmax that can avoid torque steer during turning acceleration is set, and the TCS control during turning is changed to a threshold value corresponding to the drive torque upper limit value Pmax. Therefore, torque steer is avoided by operating the TCS control even if the slip rate at which the transmittable torque has not yet reached the upper limit.

FIG. 12 is a flowchart illustrating torque steer avoidance control according to the third embodiment.
In step 401, road surface μ estimation processing is executed. Since the basic estimation process is the same as that of the first embodiment, description thereof is omitted.
In step 402, it is determined whether or not the vehicle is turning based on the sensor value from the lateral acceleration sensor 13. If the vehicle is not turning, the present control flow ends . If the vehicle is turning, the process proceeds to step 403.
In step 403, the drive torque P * is calculated. Here, the driving torque P * represents a value that estimates how much driving force is output from the engine 1 by the driver's accelerator pedal operation.
In step 404, based on the lateral acceleration detected by the lateral acceleration sensor 13, the driving force upper limit value Pmax is set from the upper limit value map shown in FIG.
In step 405, it is determined whether or not the driving torque P * is larger than the driving force upper limit value Pmax. If it is larger, the process proceeds to step 406. Otherwise, the process proceeds to step 407.
In step 406, the driving force upper limit value Pmax is output as the driving force command value.
In step 407, the drive torque P * is output as the drive force command value.
In step 408, the slip ratio threshold value in the TCS control is changed to a slip ratio threshold value corresponding to the driving force upper limit value Pmax.

[Operation of torque steer avoidance control]
The effect | action of the torque steer avoidance control of Example 3 is demonstrated. In FIG. 8, at a certain lateral acceleration and road surface μ, the inner turning wheel causes slipping, and the first drive shaft driving torque on the turning inner wheel side does not become larger than the first drive shaft driving torque of the turning outer wheel due to torque reverse. The drive torque upper limit value Pmax is set. With reference to this drive torque upper limit value Pmax and a map showing the relationship between the slip ratio shown in FIG. 13 and the torque that can be transmitted from the front wheels 5FL, 5FR to the road surface, the slip ratio corresponding to the drive torque upper limit value Pmax is controlled during turning TCS control. Set as threshold.

  Therefore, if the slip ratio exceeds the TCS control threshold value during turning, there is still a margin as the transmittable torque, but torque steer may occur, so the slip ratio is smaller than the TCS control threshold value during turning by TCS control. Thus, the driving torque of the front wheels 5FL and 5FR is controlled. Thereby, torque steer during turning acceleration can be avoided by diverting the TCS control logic. Since the map shown in FIG. 8 is set according to the lateral acceleration, the TCS control threshold value during turning is also changed according to the lateral acceleration.

  As described above, the vehicle attitude control device according to the third embodiment provides the following effects in addition to the functions and effects of the first and second embodiments.

  (7) When the slip ratio exceeds the normal threshold, in a vehicle capable of executing the TCS control so as to suppress the slip, the vehicle is turning and the turning outer wheel is larger than the steering wheel driving torque on the turning inner wheel side. The steering wheel driving torque on the side of the turning and the steering wheel driving torque on the side of the turning outer wheel are reduced based on the turning state. Change the threshold of TCS control. Thereby, torque steer during turning acceleration can be easily avoided by diverting the TCS control logic.

  As mentioned above, although the vehicle attitude | position control apparatus of this invention has been demonstrated based on Examples 1-3, it is not restricted to these Examples about a concrete structure, The invention which concerns on each claim of a claim Design changes and additions are permitted without departing from the gist of the present invention.

  For example, in the first and third embodiments, the turning state is determined based on the lateral acceleration. However, the turning state may be determined from the yaw rate generated in the vehicle using the yaw rate sensor 12.

  Further, the turning state may be detected based on the difference between the left and right rotational speeds of the left and right front wheels 5FL and 5FR. That is, in a situation where no torque steer occurs, the rotation speed of the inner turning wheel should be smaller than the rotation speed of the outer turning wheel. However, if the wheel load of the turning inner wheel is reduced and slip occurs, torque reverse may be caused. Therefore, when the rotation speed of the turning inner wheel is larger than the rotation speed of the turning outer wheel, the torque steer avoidance control may be executed.

  Further, the turning state may be detected based on the driving torque of the steering wheel. In other words, the steered wheel drive torque may be estimated and calculated, and torque steer avoidance control may be executed from the left-right difference of the drive torque.

  In the first and second embodiments, the ECU 20 is configured to output a command for controlling the driving force so as to be equal to or lower than the torque upper limit value Pmax. However, if the driving torque acting on the steered wheels can be controlled. Other configurations are also included in the present invention. For example, a command to upshift the gear ratio may be output to the ATCU 30. Specifically, the output torque can be reduced by upshifting the automatic transmission 2. In addition, a brake unit that can increase or decrease the wheel cylinder pressure regardless of the driver's brake pedal operation is provided, and by outputting a command to suppress the steering wheel driving torque by this brake unit, the driving torque of the steering wheel is output. May be controlled.

  Further, in the first embodiment, the torque steer avoidance control associated with the torque reverse is configured separately, and in the second embodiment, the torque steer avoidance control associated with the load change is separately configured. Avoidance control may be achieved. Further, the first and second embodiments may be configured using the TCS control of the third embodiment, and is not particularly limited.

1 is a schematic diagram illustrating a configuration of a vehicle attitude control device according to a first embodiment. FIG. 3 is a control block diagram illustrating a configuration of a control unit according to the first embodiment. 6 is a flowchart illustrating torque steer avoidance control processing in the control unit of the first embodiment. 3 is a flowchart illustrating a road surface μ estimation process according to the first embodiment. It is a figure showing the relationship between the steered wheel drive torque of Example 1, and slip time. It is a figure showing the relationship between the front wheel of Example 1, and a differential. It is a figure showing the mechanical structure of the differential of Example 1, and the relationship between the drive torque output from an engine when a left front wheel slips, and the drive torque of a 1st drive shaft. It is a figure showing the relationship between the lateral acceleration of Example 1, road surface micro | micron | mu, and drive torque upper limit Pmax. It is a figure showing the relationship between the front wheel at the time of the left turn of Example 2, a 1st drive shaft, and a 2nd drive shaft. 6 is a flowchart illustrating torque steer avoidance control according to a second embodiment. It is a figure showing the relationship between the suspension stroke difference of Example 2, road surface micro | micron | mu, and a driving torque upper limit. 12 is a flowchart illustrating torque steer avoidance control according to a third embodiment. It is a figure showing the relationship between the slip ratio of Example 3, and the torque which can be transmitted to a road surface from a front wheel.

Explanation of symbols

1 Engine 2a Differential 2 Automatic transmission 3 Steering wheel 4 Rack & pinion mechanism 5FL Left front wheel 5FR Right front wheel 5RL Left rear wheel 5RR Right rear wheel 10 Control unit 11 Wheel speed sensor 12 Yaw rate sensor 13 Lateral acceleration sensor 14 Steering angle sensor 15 Accelerator Pedal stroke sensor 16 Suspension stroke sensor 20 Engine control unit 30 Automatic transmission control unit 41 Rack shaft 42 Tie rod 43 Axle
SG side gear
SL1, SR1 first drive shaft
SL2, SR2 second drive shaft
SPL left suspension
SPR right suspension
UJ universal joint
WS washer

Claims (10)

In a vehicle attitude control device provided with steered wheels driven by a drive source through a differential gear,
A vehicle is turning, the rotation number of the turning inner wheel side steering wheel is increased by idling, the turning inner wheel side of the steering-wheel drive turning outer side than the torque by reducing the rotational speed of the turning outer wheel side steering wheel A turning state detecting means for detecting a turning state in which the steered wheel drive torque increases,
Based on the turning state detected by the turning state detection means, the upper limit of the driving torque of the drive source is set such that the difference between the steering wheel driving torque on the turning inner wheel side and the steering wheel driving torque on the turning outer wheel side is reduced. Torque upper limit setting means for setting a value;
Driving force control means for controlling the driving force of the steered wheels within a range equal to or lower than the upper limit value set by the torque upper limit setting means;
A vehicle attitude control device comprising: In a vehicle attitude control device having a steering wheel driven through a universal joint by a drive source,
A turning state detecting means for detecting a change in steering wheel load on a turning inner wheel during turning of the vehicle, and detecting a change in a joint angle of the universal joint;
Based on the turning state detected by the turning state detection means, the upper limit of the driving torque of the drive source is set such that the difference between the steering wheel driving torque on the turning inner wheel side and the steering wheel driving torque on the turning outer wheel side is reduced. Torque upper limit setting means for setting a value;
Driving force control means for controlling the driving force of the steered wheels within a range equal to or lower than the upper limit value set by the torque upper limit setting means;
A vehicle attitude control device comprising: The vehicle attitude control device according to claim 1 or 2,
A driving slip state amount detecting means for detecting a driving slip state amount of the steering wheel;
When the drive slip state quantity detected by the drive slip state quantity detection means exceeds a threshold value that causes a reduction in traction between the steered wheels and the road surface, a drive torque upper limit value capable of suppressing the drive slip state quantity is set. Traction control means to be set;
With
The vehicle attitude control device, wherein the driving force control means changes a threshold value of the traction control means so that the driving torque upper limit value set by the torque upper limit value setting means is obtained. The vehicle attitude control device according to any one of claims 1 to 3,
The vehicle posture control device characterized in that the turning state detecting means detects the turning state based on a value corresponding to a lateral acceleration of the vehicle. The vehicle attitude control device according to any one of claims 1 to 4,
The vehicle posture control device, wherein the turning state detecting means detects the turning state based on a yaw rate equivalent value of the vehicle. The vehicle attitude control device according to any one of claims 1 to 5,
The vehicle posture control device characterized in that the turning state detecting means detects the turning state based on a difference between left and right rotational speeds of the steered wheels. The vehicle attitude control device according to any one of claims 1 to 6,
The vehicle posture control device characterized in that the turning state detecting means detects the turning state based on a driving torque of the steering wheel. The vehicle attitude control device according to any one of claims 1 to 7,
The vehicle posture control device characterized in that the turning state detecting means detects the turning state based on a suspension stroke of the steering wheel. The vehicle attitude control device according to any one of claims 1 to 8,
A road surface friction coefficient estimating means for estimating the road surface friction coefficient is provided,
The torque upper limit setting means sets the smaller upper limit value as the estimated road surface friction coefficient is lower. The vehicle attitude control device according to claim 9, wherein
The road surface friction coefficient estimating means is
A reference time setting unit for setting a reference time until a steered wheel drive slip occurs at the set first steered wheel drive torque, based on a preset initial road surface friction coefficient;
A measuring unit for measuring a slip time from when the first steered wheel drive torque is reached until a drive slip of the steered wheel occurs;
The reference time and the slip time are compared, and when the slip time is shorter than the reference time, it is updated to a road surface friction coefficient smaller than the initial road surface friction coefficient, and when the slip time is longer than the reference time A road surface friction coefficient correction unit for updating to a road surface friction coefficient larger than the initial road surface friction coefficient;
A vehicle attitude control device comprising:

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