JP2006213160A - Behavior control device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance the running stability of a vehicle in the situation that the friction coefficient of the road surface is lower than conventional, by controlling the rolling stiffness distribution over the front and the rear wheels according to the friction coefficient of the road surface. <P>SOLUTION: When the control mode selected is the snow mode (S20) or the friction coefficient μ of the road surface is lower than the reference value μo (S30), the target rolling stiffness Kt of the whole vehicle when μ is low, is calculated so as to be smaller than when μ high (S60), while the target rolling stiffness distribution Rft to the front wheels when μ is low, is calculated so as to be larger than when μ high (S70), and active stabilizer devices 16 and 18 are controlled in the snow mode on the basis of the target rolling stiffness Kt of the whole vehicle and the target rolling stiffness distribution Rft to the front wheels, and the steering transmitting ratio of the steering system is lowered (S60-100). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a vehicle behavior control device, and more particularly to a vehicle behavior control device by controlling the roll rigidity of a vehicle.

As one of behavior control devices for vehicles such as automobiles, for example, as described in Patent Document 1 below, in a vehicle capable of controlling the roll rigidity of a vehicle, the vehicle can travel on a road with a low friction coefficient on the road surface. 2. Description of the Related Art Conventionally, a behavior control apparatus configured to reduce the roll rigidity of a vehicle when traveling and thereby secure a grip on the road surface of a wheel, particularly a turning inner wheel, to suppress an understeer tendency of the vehicle is conventionally known.
JP-A-5-238222

  However, in the conventional behavior control apparatus as described above, it is not enough how to control the roll stiffness distribution of the front and rear wheels in reducing the roll stiffness of the vehicle in a situation where the friction coefficient of the road surface is low. It has not been studied and needs to be improved in order to improve the running stability of the vehicle when the vehicle runs on a road with a low friction coefficient on the road surface.

  The present invention has been made in view of the above-described problems in the conventional behavior control apparatus configured to reduce the roll rigidity of the vehicle when the road friction coefficient is low compared to when the road friction coefficient is high. The main problem of the present invention is to control the distribution of roll rigidity of the front and rear wheels in accordance with the friction coefficient of the road surface, thereby stabilizing the running of the vehicle in a situation where the friction coefficient of the road surface is lower than the conventional one. Is to improve the performance.

  According to the present invention, the main problem described above is the configuration of claim 1, that is, roll stiffness distribution variable means for changing the roll stiffness distribution of the front and rear wheels, means for detecting the friction coefficient of the road surface, and the friction coefficient of the road surface. It is achieved by a vehicle behavior control device characterized by having control means for controlling the roll stiffness distribution closer to the front wheels when the road surface friction coefficient is low than when the road surface friction coefficient is high.

  According to the present invention, in order to effectively achieve the main problems described above, in the configuration of claim 1, the roll stiffness distribution varying means can change the roll stiffness of the entire vehicle, and the control The means is configured to lower the roll rigidity of the entire vehicle when the road surface friction coefficient is low than when the road surface friction coefficient is high.

  According to the present invention, in order to effectively achieve the above-mentioned main problems, in the configuration of claim 1 or 2, the vehicle has means for changing the steering transmission ratio from the steering input means to the steered wheels. And the control means is configured to lower the steering transmission ratio when the road surface friction coefficient is low than when the road surface friction coefficient is high.

  In general, the lower the friction coefficient of the road surface, the more likely the vehicle behavior becomes unstable, and as the roll stiffness distribution of the front and rear wheels becomes closer to the front wheels, the vehicle's steering characteristics change toward the understeer direction and the vehicle's steering response decreases. At the same time, the running stability of the vehicle is improved.

  According to the first aspect of the present invention, when the road surface friction coefficient is low, the roll rigidity distribution is controlled closer to the front wheel than when the road surface friction coefficient is high, and the roll rigidity on the front wheel side is the roll rigidity on the rear wheel side. Since it is relatively high compared to the above, while ensuring good steering response when the friction coefficient of the road surface is high, the steering characteristic of the vehicle when the friction coefficient of the road surface is low is changed to the understeer direction, The running stability of the vehicle can be improved.

  Further, according to the configuration of the second aspect, when the road surface friction coefficient is low, the roll rigidity distribution is controlled closer to the front wheels and the roll rigidity of the entire vehicle is reduced compared to when the road surface friction coefficient is high. When the road surface friction coefficient is high, the roll of the vehicle is effectively suppressed, and when the road surface friction coefficient is low, the turning lateral force acting on the vehicle is absorbed by the vehicle roll, and suddenly between the left and right wheels. Load movement and sudden changes in vehicle behavior resulting therefrom can be effectively prevented.

  According to the third aspect of the present invention, when the road surface friction coefficient is low, the steering transmission ratio is lowered as compared with when the road surface friction coefficient is high. While ensuring the steering response, when the road surface friction coefficient is low, it prevents the steered wheels from being steered suddenly even if the driver steers suddenly. It is possible to effectively prevent a load change and a sudden change in vehicle behavior resulting from the load movement.

[Preferred embodiment of problem solving means]
According to one preferred aspect of the present invention, in the configuration of claims 1 to 3, the roll stiffness distribution variable means includes a roll stiffness variable means on the front wheel side and a roll stiffness variable means on the rear wheel side. (Preferred embodiment 1).
According to another preferred embodiment of the present invention, in the configuration of the preferred embodiment 1, the control means increases the roll rigidity on the front wheel side by the roll rigidity variable means on the front wheel side and roll rigidity on the rear wheel side. It is comprised so that the roll rigidity by the side of a rear wheel may be made low by a variable means (Preferred aspect 2).

According to another preferred aspect of the present invention, in the configuration of the first to third aspects, the roll stiffness distribution variable means is configured to include roll stiffness variable means provided on the rear wheel side (preferably. Aspect 3).
According to another preferred aspect of the present invention, in the structure of the preferred aspect 3, the control means is configured to lower the roll rigidity on the front wheel side by the roll rigidity variable means on the front wheel side (preferred aspect 4). ).

  According to another preferred embodiment of the present invention, in the configurations of the preferred embodiments 1 to 4, the roll stiffness varying means is configured to include an active stabilizer capable of increasing / decreasing the anti-roll moment (preferred embodiment 5). ).

  According to another preferred embodiment of the present invention, in the configurations of the preferred embodiments 1 to 5, the roll stiffness varying means is configured to include a suspension spring device capable of increasing and decreasing the spring constant (preferred embodiment 6). ).

  According to another preferred aspect of the present invention, in the configurations of the preferred aspects 1 to 6, the roll stiffness variable means is provided corresponding to each wheel, and the active load capable of increasing / decreasing the support load of the corresponding wheel is provided. It is comprised so that a suspension apparatus may be included (Preferred aspect 7).

  According to another preferred embodiment of the present invention, in the configuration of the above-described claims 1 to 3 or the preferred embodiments 1 to 7, the vehicle is disposed between the sprung and unsprung portions of each wheel. Damping force varying means is provided, and the damping force of the damping force varying means is configured to be lower when the road surface friction coefficient is low than when the road surface friction coefficient is high (preferred aspect 8).

  According to another preferred embodiment of the present invention, in the configuration of claim 3, the means for changing the steering transmission ratio drives the steering wheel side member relative to the steering input means side member. It is comprised so that a steering transmission ratio may be changed (preferable aspect 9).

  According to another preferred aspect of the present invention, in the configuration of the preferred aspect 7, the means for changing the steering transmission ratio rotationally drives the steering wheel side rotation member relative to the steering input means side rotation member. By doing so, the steered wheels are configured to be steered (preferred aspect 10).

  The present invention will now be described in detail with reference to the accompanying drawings.

  FIG. 1 schematically shows an embodiment of a vehicle behavior control device according to the present invention applied to a vehicle having an active stabilizer device on the front wheel side and the rear wheel side and having a turning angle varying device functioning as an automatic turning device. It is a block diagram.

  In FIG. 1, 10FL and 10FR indicate the left and right front wheels of the vehicle 12, respectively, and 10RL and 10RR indicate the left and right rear wheels of the vehicle 12, respectively. An active stabilizer device 16 is provided between the left and right front wheels 10FL and 10FR, and an active stabilizer device 18 is provided between the left and right rear wheels 10RL and 10RR. The active stabilizer devices 16 and 18 function as roll stiffness changing means for applying an anti-roll moment to the vehicle (vehicle body) and increasing / decreasing the roll stiffness on the front wheel side and the rear wheel side as required.

  The active stabilizer device 16 is integrally connected to a pair of torsion bar portions 16TL and 16TR extending coaxially with each other along an axis extending in the lateral direction of the vehicle, and to the outer ends of the torsion bar portions 16TL and 16TR, respectively. And a pair of arm portions 16AL and 16AR. The torsion bar portions 16TL and 16TR are respectively supported by a vehicle body not shown in the drawing via brackets not shown in the drawing so as to be rotatable around its own axis. The arm portions 16AL and 16AR extend in the longitudinal direction of the vehicle so as to intersect the torsion bar portions 16TL and 16TR, respectively, and the outer ends of the arm portions 16AL and 16AR are respectively left and right through rubber bush devices not shown in the drawing. The front wheels 10FL and 10FR are connected to suspension members 14FL and 14FR such as suspension arms.

  The active stabilizer device 16 has an actuator 20F between the torsion bar portions 16TL and 16TR. The actuator 20F drives the pair of torsion bar portions 16TL and 16TR to rotate relative to each other as necessary, so that when the left and right front wheels 10FL and 10FR bounce and rebound in opposite phases, the wheel bounces due to torsional stress. By changing the force for suppressing rebound, the anti-roll moment applied to the vehicle at the positions of the left and right front wheels is increased or decreased, and the roll rigidity of the vehicle on the front wheel side is variably controlled.

  Similarly, the active stabilizer device 18 has a pair of torsion bar portions 18TL and 18TR extending coaxially with each other along an axis extending in the lateral direction of the vehicle, and the outer ends of the torsion bar portions 18TL and 18TR, respectively. It has a pair of arm portions 18AL and 18AR connected together. The torsion bar portions 18TL and 18TR are respectively supported by a vehicle body not shown in the drawing via brackets not shown in the drawing so as to be rotatable around its own axis. The arm portions 18AL and 18AR extend in the longitudinal direction of the vehicle so as to intersect the torsion bar portions 18TL and 18TR, respectively, and the outer ends of the arm portions 18AL and 18AR are respectively left and right through rubber bushing devices not shown in the drawing. The suspension members 14RL and 14RR such as the suspension arms of the rear wheels 10RL and 10RR are connected.

  The active stabilizer device 18 has an actuator 20R between the torsion bar portions 18TL and 18TR. The actuator 20R drives the pair of torsion bar portions 18TL and 18TR to rotate relative to each other as necessary, so that when the left and right rear wheels 10RL and 10RR bounce and rebound in opposite phases, the wheel bounces due to torsional stress. By changing the force to suppress rebound, the anti-roll moment applied to the vehicle at the positions of the left and right rear wheels is increased or decreased, and the roll rigidity of the vehicle on the rear wheel side is variably controlled.

  Since the structures of the active stabilizer devices 16 and 18 do not form the gist of the present invention, any structure known in the art can be used as long as the roll rigidity of the vehicle can be variably controlled. However, for example, the active stabilizer device described in Japanese Patent Application No. 2003-324212 (reference number AT-5552) specification and drawings relating to the application of the present applicant, that is, a drive gear fixed to the inner end of one torsion bar portion is provided. An electric motor having an attached rotating shaft and a driven gear that is fixed to the inner end of the other torsion bar portion and meshes with the driving gear. The driving gear and the driven gear transmit the rotation of the driving gear to the driven gear. The active stabilizer device is preferably a gear that does not transmit the rotation of the driven gear to the drive gear.

  The actuators 20F and 20R of the active stabilizer devices 16 and 18 are controlled by the electronic control device 22. Although not shown in detail in FIG. 1, the electronic control unit 22 includes a CPU, a ROM, a RAM, and an input / output port device, which are connected to each other via a bidirectional common bus and a drive circuit. It may be better.

  In the illustrated embodiment, as shown in FIG. 1, the left and right front wheels 10FL and 10FR are driven in response to the operation of the steering wheel 24 by the driver. 26 is steered by the rack bar 28 and the tie rods 30L and 30R.

  The steering wheel 24 is connected to a pinion shaft 40 of the power steering device 26 via an upper steering shaft 32 as a first steering shaft, a turning angle varying device 34, a lower steering shaft 36 as a second steering shaft, and a universal joint 38. Drive connected. In the illustrated embodiment, the turning angle varying device 34 is connected to the lower end of the upper steering shaft 32 on the side of the housing 34A and is connected to the upper end of the lower steering shaft 36 on the side of the rotor 34B. An electric motor 42 for turning driving is included.

  Thus, the steering angle varying device 34 drives the lower steering shaft 36 to rotate relative to the upper steering shaft 32, so that the ratio of the steering angles of the left and right front wheels 10 FL and 10 FR, which are the steering wheels, with respect to the rotation angle of the steering wheel 24. That is, it functions as a steering transmission ratio variable means for changing the steering transmission ratio (the reciprocal of the steering gear ratio), and is controlled by the electronic control unit 44. Although not shown in detail in FIG. 1, the electronic control unit 44 also has a CPU, a ROM, a RAM, and an input / output port unit, which are connected to each other via a bidirectional common bus and a drive circuit. It may be better.

  As shown in FIG. 1, the electronic control unit 22 is operated by a signal indicating the vehicle speed V detected by the vehicle speed sensor 48, a signal indicating the friction coefficient μ of the road surface detected by the μ sensor 50, and a vehicle occupant. A mode selection switch (SW) 52 receives a signal indicating whether the control mode is the normal mode or the snow mode. The electronic control unit 22 receives signals indicating the actual rotation angles φF and φR of the actuators 20F and 20R detected by the rotation angle sensors 54F and 54R.

  On the other hand, the electronic control unit 44 indicates the signal indicating the steering angle θ detected by the steering angle sensor 56 and the relative rotation angle θre detected by the rotation angle sensor 58, that is, the relative rotation angle of the lower steering shaft 36 with respect to the upper steering shaft 32. The signal shown is input. The electronic control units 22 and 44 communicate with each other and exchange necessary signals.

  The electronic control unit 22 stores a behavior control routine according to the flowchart shown in FIG. 2 and a map corresponding to the graphs shown in FIGS. 4 and 5, and based on the road surface friction coefficient μ and the vehicle speed V, the entire vehicle is controlled. The target roll stiffness Kt is calculated, the target roll stiffness distribution ratio Rft on the front wheel side is calculated as a value larger than 0 and smaller than 1 based on the friction coefficient μ of the road surface and the vehicle speed V, and the target roll stiffness Kt and front wheels of the entire vehicle are calculated. The target roll stiffness Kft on the front wheel side and the target roll stiffness Krt on the rear wheel side are calculated based on the target roll stiffness distribution ratio Rft on the side, so that the roll stiffness on the front wheel side and the rear wheel side becomes the target roll stiffness Kft and Krt, respectively. Actuators 20F and 20R are controlled.

  Further, when the control mode selected by operating the mode selection switch 52 is the snow mode, the electronic control unit 22 outputs a command signal for setting the steering gear ratio control mode to the normal mode to the electronic control unit 44. When the control mode selected by the operation of the mode selection switch 52 is the snow mode or when the road surface friction coefficient μ is less than the reference value μo (positive constant), the steering gear ratio with respect to the electronic control unit 44 is determined. A command signal for setting the control mode to the snow mode is output.

  On the other hand, the electronic control unit 44 stores a steering gear ratio control routine according to the flowchart shown in FIG. 3 and a map corresponding to the graph shown in FIG. 6, and the control command input from the electronic control unit 22 is in the normal mode. If the target steering gear ratio Rgt is calculated from the map corresponding to the graph shown by the solid line in FIG. 6 based on the vehicle speed V, and the control command input from the electronic control unit 22 is in the snow mode. Based on the vehicle speed V, the target steering gear ratio Rgt is calculated from the map corresponding to the graph shown by the broken line in FIG. 6, and based on the steering angle θ indicating the driver's steering operation amount and the target steering gear ratio Rgt. The target steering angle δt of the left and right front wheels is calculated, and the turning angle varying device 34 is controlled so that the steering angle δ of the left and right front wheels becomes the target steering angle δt.

  Next, a behavior control routine in the embodiment will be described with reference to the flowchart shown in FIG. The control according to the flowchart shown in FIG. 2 is started by closing an ignition switch not shown in the figure, and is repeatedly executed at predetermined time intervals.

  First, in step 10, a signal indicating the vehicle speed V detected by the vehicle speed sensor 48 is read, and in step 20, the control mode selected by operating the mode selection switch 52 is the snow mode. If a positive determination is made, the process proceeds to step 60. If a negative determination is made, that is, if it is determined that the selected control mode is the normal mode, the process proceeds to step 30. .

  In step 30, it is determined whether or not the friction coefficient μ of the road surface is less than the reference value μo. If an affirmative determination is made, the process proceeds to step 60. If a negative determination is made, the process proceeds to step 40. The active stabilizer devices 16 and 18 are controlled in any manner known in the art, and in step 50, a command signal for setting the steering gear ratio control mode to the normal mode to the electronic control device 44. Is output.

  In step 60, when the road surface friction coefficient μ is low, the target roll rigidity Kt of the entire vehicle is lower than when the road surface friction coefficient μ is high, and when the vehicle speed V is low, it is compared with when the vehicle speed V is high. Then, the target roll stiffness Kt of the entire vehicle is calculated from the map corresponding to the graph shown in FIG. 4 based on the friction coefficient μ of the road surface and the vehicle speed V so that the target roll stiffness Kt of the entire vehicle becomes low.

  In step 70, when the road surface friction coefficient μ is low, the target roll stiffness distribution ratio Rft on the front wheel side is higher than when the road surface friction coefficient μ is high, and when the vehicle speed V is high, the vehicle speed V is low. The target roll stiffness distribution ratio Rft on the front wheel side is determined from the map corresponding to the graph shown in FIG. 5 based on the friction coefficient μ of the road surface and the vehicle speed V so that the target roll stiffness distribution ratio Rft on the front wheel side is higher than that in FIG. Calculated.

In step 80, the target roll stiffness Kft on the front wheel side and the target roll stiffness Krt on the rear wheel side are calculated according to the following equations 1 and 2, respectively.
Kft = RftKt (1)
Krt = (1-Rft) Kt (2)

  In step 90, the active stabilizer devices 16 and 18 are controlled in the snow mode so that the roll rigidity on the front wheel side and the rear wheel side becomes the target roll rigidity Kft on the front wheel side and the target roll rigidity Krt on the rear wheel side, respectively. In step 100, a command signal to the effect that the steering gear ratio control mode should be set to the snow mode is output to the electronic control unit 44.

  Next, a control routine for the steering gear ratio in the illustrated embodiment will be described with reference to the flowchart shown in FIG. Note that the control according to the flowchart shown in FIG. 3 is also started by closing an ignition switch (not shown), and is repeatedly executed at predetermined time intervals.

  First, at step 110, a signal indicating the steering angle θ is read, and at step 20, whether or not the steering gear ratio control mode by the command signal from the electronic control unit 22 is the snow mode. If a determination is made and an affirmative determination is made, the process proceeds to step 140. If a negative determination is made, the process proceeds to step 130.

  In step 130, the target steering gear ratio Rgt is calculated from a map corresponding to the graph shown by the solid line in FIG. 6 based on the vehicle speed V. In step 140, the target steering gear ratio Rgt is calculated based on the vehicle speed V in FIG. Then, the target steering gear ratio Rgt is calculated from the map corresponding to the graph indicated by the broken line, and in step 150, the turning angle varying device 34 is controlled so that the steering gear ratio becomes the target steering gear ratio Rgt. .

  Thus, according to the illustrated embodiment, when the control mode selected by the operation of the mode selection switch 52 is the normal mode, a negative determination is made in step 20, but the road friction coefficient μ is the reference value μo. If it is less than the predetermined value, an affirmative determination is made in step 30, and in steps 60 and 70, the target roll stiffness Kt of the entire vehicle and the target roll stiffness distribution ratio Rft on the front wheel side are determined based on the friction coefficient μ of the road surface and the vehicle speed V. In step 80, the target roll stiffness Kft on the front wheel side and the target roll stiffness Krt on the rear wheel side are calculated according to the above equations 1 and 2, respectively. In step 90, the active stabilizer devices 16 and 18 are in the snow mode. It is controlled by.

  Further, when the control mode selected by the operation of the mode selection switch 52 is the snow mode, an affirmative determination is made in step 20, so that the road surface friction coefficient μ is less than the reference value μo. Steps 60 to 100 are executed, and the active stabilizer devices 16 and 18 are controlled in the snow mode.

  In this case, since the target roll stiffness distribution ratio Rft on the front wheel side is calculated so as to be higher when the road surface friction coefficient μ is low than when the road surface friction coefficient μ is high, according to the illustrated embodiment, the road surface When the friction coefficient μ of the road surface is low, the roll rigidity distribution of the front and rear wheels is controlled closer to the front wheels than when the road surface friction coefficient μ is high, thereby ensuring good steering response when the road surface friction coefficient is high. On the other hand, it is possible to reliably improve the running stability of the vehicle by changing the steering characteristic of the vehicle when the road surface friction coefficient is low in the understeer direction.

  In particular, according to the illustrated embodiment, the target roll stiffness distribution ratio Rft on the front wheel side is calculated to be higher when the vehicle speed V is high than when the vehicle speed V is low. While preventing the roll stiffness distribution ratio Rft from becoming excessively high and preventing the vehicle from understeering excessively, the target roll rigidity distribution ratio Rft on the front wheel side is reliably controlled closer to the front wheels when the vehicle speed V is high. Thus, it is possible to effectively improve the running stability of the vehicle when the vehicle travels at a medium to high speed on a traveling path having a low friction coefficient.

  Further, according to the illustrated embodiment, the target roll stiffness Kt of the entire vehicle is calculated so as to be lower when the road surface friction coefficient μ is lower than when the road surface friction coefficient μ is high. When it is high, the roll of the vehicle can be effectively suppressed, and when the friction coefficient of the road surface is low, the turning lateral force acting on the vehicle is absorbed by the roll of the vehicle, and sudden load movement between the left and right wheels It is possible to effectively prevent a sudden change in vehicle behavior due to the above.

  Further, according to the illustrated embodiment, the target roll stiffness Kt of the entire vehicle is calculated to be lower when the vehicle speed V is low than when the vehicle speed V is high. Therefore, when the vehicle speed V is high, the target roll stiffness of the entire vehicle is calculated. Kt can be increased to effectively suppress the rolling of the vehicle when turning, and when the vehicle speed V is low, the target roll stiffness Kt of the entire vehicle is lowered, so that the vehicle travels on a low-coefficient running path to a medium / low speed. The lateral force acting on the vehicle when the vehicle is traveling can be absorbed by the vehicle roll, and a sudden load movement between the left and right wheels and a sudden change in the vehicle behavior due to this can be effectively prevented. .

  Further, according to the illustrated embodiment, the control mode selected by the operation of the mode selection switch 52 is the normal mode, but the road surface friction coefficient μ is less than the reference value μo, and the mode selection switch 52 is operated. When the control mode selected by the above is the normal mode, a command signal to the effect that the steering gear ratio control mode should be set to the snow mode is output to the electronic control unit 44 in step 100. Then, an affirmative determination is made at step 120 of the flowchart shown in FIG. 3, a target steering gear ratio Rgt is calculated based on the vehicle speed V at step 140, and the steering gear ratio is converted to the target steering gear at step 150. The turning angle varying device 34 is controlled so as to have the ratio Rgt.

  In this case, the target steering gear ratio Rgt is calculated to a higher value at least in the medium / low speed range than when the control mode is the normal mode, so that when the road surface friction coefficient is low, the road surface friction coefficient is high. Since the steering transmission ratio is sometimes reduced, it is possible to ensure a good steering response of the vehicle when the road surface friction coefficient is high, and when the road surface friction coefficient is low, the driver can steer more rapidly. Even if it is carried out, it is possible to prevent the steered wheels from being steered suddenly, thereby effectively preventing a sudden load movement between the left and right wheels and a sudden change in vehicle behavior resulting therefrom. .

  In addition, when roll stiffness changing means such as an active stabilizer is provided only on the front wheel side or the rear wheel side, controlling the front / rear wheel distribution ratio of the roll stiffness will unambiguously change the roll stiffness of the entire vehicle. The front and rear wheel distribution ratio of the roll rigidity and the roll rigidity of the entire vehicle cannot be controlled independently of each other.

  On the other hand, according to the illustrated embodiment, the roll stiffness distribution variable means comprises a roll rigidity variable means on the front wheel side and a roll rigidity variable means on the rear wheel side, and each roll rigidity variable means can increase / decrease the anti-roll moment. Therefore, the front and rear wheel distribution ratio of the roll rigidity and the roll rigidity of the entire vehicle can be controlled independently of each other. Therefore, the front and rear wheel distribution ratio of the roll rigidity according to the friction coefficient μ of the road surface and the vehicle speed V. And the roll rigidity of the entire vehicle can be optimally controlled.

  Although the present invention has been described in detail with reference to specific embodiments, the present invention is not limited to the above-described embodiments, and various other embodiments are possible within the scope of the present invention. It will be apparent to those skilled in the art.

  For example, in the above-described embodiment, the roll stiffness distribution varying means includes the front wheel side active stabilizer device 16 as the front wheel side roll stiffness varying means and the rear wheel side active stabilizer device 18 as the rear wheel side roll stiffness varying means. However, the roll stiffness distribution varying means may be provided only on the front wheel side or the rear wheel side. Particularly, the roll stiffness distribution varying means is provided only on the rear wheel side, and the road surface friction coefficient is low. In this case, the roll stiffness distribution ratio may be controlled closer to the front wheels and the roll stiffness of the entire vehicle may be reduced by reducing the rear wheel roll stiffness.

  In the above-described embodiment, the roll stiffness distribution varying means includes the front wheel side active stabilizer device 16 as the front wheel side roll stiffness varying means and the rear wheel side active stabilizer device 18 as the rear wheel side roll stiffness varying means. However, the roll stiffness variable means may be a suspension spring device capable of increasing / decreasing the spring constant or an active suspension device provided corresponding to each wheel and capable of increasing / decreasing the support load of the corresponding wheel, These and the active stabilizer device may be combined.

  In the above embodiment, the damping force of the shock absorber is not controlled. However, when the shock absorber is a shock absorber of variable damping force type, the road surface is reduced when the friction coefficient μ of the road surface is low. The damping force is variable with the control of the roll stiffness distribution ratio or the roll stiffness of the entire vehicle so that the damping force (damping coefficient) of the damping force variable means such as a variable damping force type shock absorber is lower than when the friction coefficient μ of the vehicle is high. It may be modified so that the damping force of the means is controlled.

  In the above embodiment, the target roll stiffness distribution ratio Rft on the front wheel side and the target roll stiffness Kt of the entire vehicle are variably set not only by the road surface friction coefficient μ but also by the vehicle speed V. The target roll stiffness distribution ratio Rft on the front wheel side or the target roll stiffness Kt of the entire vehicle may be modified so as to be variably set only in accordance with the friction coefficient μ of the road surface.

  Further, in the above-described embodiment, the means for changing the steering transmission ratio drives the steering wheel by turning the rotation member on the steering wheel side relative to the rotation member on the steering input means side. However, this means may be of any configuration as long as the steering transmission ratio can be changed, such as a configuration in which the tie rod is expanded and contracted.

It is a schematic block diagram which shows the Example of the vehicle behavior control apparatus by this invention applied to the vehicle provided with the steering angle variable apparatus which has an active stabilizer apparatus on the front-wheel side and the rear-wheel side, and functions as an automatic steering apparatus. is there. It is a flowchart which shows the behavior control routine in an Example. It is a flowchart which shows the steering gear ratio control routine in an Example. It is a graph which shows the relationship between the friction coefficient (mu) of a road surface, the vehicle speed V, and the target roll rigidity Kt of the whole vehicle. 6 is a graph showing a relationship among a road surface friction coefficient μ, a vehicle speed V, and a target roll stiffness distribution ratio Rft on the front wheel side. It is a graph which shows the relationship between the vehicle speed V and target steering gear ratio Rgt about normal mode (solid line) and snow mode (broken line).

Explanation of symbols

16, 18 Active stabilizer device 20F, 20R Actuator 22 Electronic control device 26 Power steering device 34 Steering angle variable device 44 Electronic control device 48 Vehicle speed sensor 50 μ sensor 52 Mode selection switch (SW)
56 Steering angle sensor 58 Rotation angle sensor

Claims (3)

  Roll stiffness distribution variable means for changing the roll stiffness distribution of the front and rear wheels, means for detecting the friction coefficient of the road surface, and when the road friction coefficient is low, the roll stiffness distribution is closer to the front wheel than when the road friction coefficient is high And a vehicle behavior control device.   The roll stiffness distribution varying means can change the roll stiffness of the entire vehicle, and the control means reduces the roll stiffness of the entire vehicle when the road surface friction coefficient is low compared to when the road surface friction coefficient is high. The vehicle behavior control device according to claim 1, wherein the vehicle behavior control device is a vehicle. The vehicle has means for changing the steering transmission ratio from the steering input means to the steered wheels, and the control means lowers the steering transmission ratio when the road friction coefficient is low compared to when the road friction coefficient is high. The vehicle behavior control device according to claim 1, wherein the vehicle behavior control device is a vehicle behavior control device.

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