JP2010215068A - Control device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for a vehicle, turning rear wheels while taking into consideration of the existence of interference with a spring upper member of the vehicle. <P>SOLUTION: A steering ECU 42 operates a target rear wheel turning angle δ<SB>rh</SB>of left and right rear wheels RW1, RW2 relevant to turning of left and right front wheels FW1, FW2. Further, the ECU 42 obtains a presumption roll angle ϕ generated on the spring upper member (vehicle body) accompanied with the turning in cooperation to a suspension ECU 41 and determines whether or not interference is generated between the rear wheels RW1, RW2 and the spring upper member when the rear wheels RW1, RW2 are turned to the target rear wheel turning angle δ<SB>rh</SB>relative to the presumption roll angle ϕ. Further, the ECU 42 requires so as to suppress roll behavior relative to the ECU 41 when the interference is generated. According to the requirement, the ECU 41 increases the spring constant of a suspension spring 11 on an outer side of turning and increases the twisting rigidity of active stabilizers 21, 22. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a vehicle control device mounted on a vehicle that can steer front and rear wheels.

  2. Description of the Related Art Conventionally, for example, a vehicle suspension control method and apparatus disclosed in Patent Document 1 below are known. This conventional control method and apparatus detects a vehicle speed and a steering angle, calculates an estimated value of lateral acceleration when the vehicle turns, calculates an estimated roll angle predicted to occur in the vehicle body, Based on the deviation between the roll angle and the estimated roll angle, the suspension damping characteristic or spring characteristic of each wheel is changed and controlled.

  Further, conventionally, for example, a vehicle control apparatus disclosed in Patent Document 2 is also known. When the vehicle turns, this conventional control device detects the vehicle speed and the rudder angle and estimates the lateral acceleration generated by the centrifugal force acting on the vehicle body, the vehicle body roll angle or the roll amount estimate value, The estimated value of the friction coefficient of the road surface is calculated, and the roll moment is calculated based on these calculated estimated values. And in this conventional control apparatus, in order to make the anti-roll moment which cancels the calculated roll moment act on a vehicle body, the drive torque or the braking torque given to each wheel is controlled.

  On the other hand, conventionally, for example, a rear wheel steering method and apparatus for a front and rear wheel steering vehicle shown in Patent Document 3 below are known. This conventional method and apparatus detects the vehicle speed and the steering angle of the front wheels, obtains the target rear wheel steering angle according to these detection values, and sets the actual rear wheel steering angle so as to converge to the target rear wheel steering angle. It comes to control.

JP 2007-106257 A Japanese Patent Laid-Open No. 2007-11083 JP 7-172336 A

  By the way, in a vehicle that can steer a rear wheel in addition to a front wheel, the steerable range of the rear wheel is generally a range in which the steered rear wheel and the sprung member displaced in the vertical direction do not interfere with each other. Set as For this reason, for example, when the rear wheel is steered in order to stabilize the behavior of the vehicle in a turning state or to improve the maneuverability, even if there is no interference with the sprung member, Since the steerable range is limited, the effect of turning the rear wheels may not be maximized.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a vehicle control device that steers rear wheels in consideration of the presence or absence of interference with a sprung member of the vehicle. is there.

  In order to achieve the above object, a feature of the present invention is a vehicle control device mounted on a vehicle capable of front-rear wheel steering, and the target steering of the rear wheels of the vehicle in relation to the steering of the front wheels of the vehicle A rear wheel steering control means for calculating the amount and controlling the steering of the rear wheel based on the target steering amount, and a roll amount representing the magnitude of the roll behavior generated in the sprung member of the vehicle with turning When the rear wheel turning control means steers the rear wheel to the target turning amount with respect to the calculated roll amount, the rear wheel after turning and the sprung member are An interference determining means for determining whether or not to interfere, and when the interference determining means determines that the rear wheel after the steering interferes with the sprung member, at least on the outside of the turn in order to avoid this interference The roll lift is controlled by controlling the operation of the suspension device of the vehicle located at In that a rolling behavior suppression control means for suppressing a.

  In this case, the roll behavior control means changes (increases or decreases) at least one of the spring constant of the suspension spring forming the suspension device, the damping force of the shock absorber, and the torsional rigidity of the active stabilizer device to thereby roll behavior. It is better to suppress this.

  According to this, since it is possible to prevent the rear wheel to be steered and the sprung member (specifically, the vehicle body) from interfering with each other, the rear wheel can be turned into a large target rear wheel if necessary. Can be steered to the corner. Therefore, since the rear wheels can always be sufficiently steered, as an effect of turning the rear wheels, for example, the turning performance of the vehicle can be greatly improved.

1 is a schematic view of a vehicle to which a control device according to an embodiment of the present invention is applied. It is the schematic which shows the structure of the electric control apparatus of FIG. 3 is a flowchart showing a rear wheel steering control program executed by the steering ECU and the suspension ECU of FIG. 1. It is a map for showing the relationship between the rear wheel target turning angle and the estimated roll angle, and for determining whether there is interference between the rear wheel after turning and the sprung member (vehicle body). It is a figure for demonstrating a target roll angle.

  Hereinafter, a vehicle control device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 schematically shows a vehicle to which a vehicle control device according to this embodiment is applied. This vehicle includes suspension devices 10FR, 10FL, 10RR, and 10RL that connect the left and right front wheels FW1 and FW2 and the rear wheels RW1 and RW2 and the sprung member HA (vehicle body). Note that the suspension devices 10FR, 10FL, 10RR, and 10RL have the same configuration, and therefore are simply referred to as the suspension device 10 in the following description.

  As shown in FIG. 1, the suspension apparatus 10 includes a suspension spring 11 and a shock absorber 12. One end (upper end) of the suspension spring 11 and the shock absorber 12 is connected to the sprung member HA, and the other end (lower end) of the shock absorber 12 is connected to the unsprung member LA. A knuckle connected to a wheel including a tire, a lower arm having one end connected to the knuckle, or the like corresponds to the unsprung member LA. The sprung member HA is a member supported by the suspension spring 11 and the shock absorber 12, and the vehicle body is also included in the sprung member HA.

  The suspension spring 11 absorbs vibration transmitted from the road surface to the sprung member HA via the wheel and the unsprung member LA. Here, in this embodiment, the suspension spring 11 is implemented by adopting an air spring whose spring constant can be changed. In this case, the spring constant of each suspension spring 11 is changed by appropriately changing the pressure in the air chamber by operating the actuator 11a (more specifically, a valve and a pump) under the control of the electric control device 40 described later. It can be changed as appropriate. The shock absorber 12 is arranged in parallel with the suspension spring 11 and attenuates the vibration. The shock absorber 12 has its damping force (more specifically, the damping coefficient) changed in stages.

  The vehicle also includes an active stabilizer device 20 that forms part of the suspension device 10 and suppresses the roll behavior that occurs in the vehicle. The active stabilizer device 20 includes a front wheel side active stabilizer 21 provided between the left and right front wheels FW1 and FW2, and a rear wheel side active stabilizer 22 provided between the left and right rear wheels RW1 and RW2. The front wheel side active stabilizer 21 and the rear wheel side active stabilizer 22 are respectively a pair of torsion bar portions 21a, 21b and torsion bar portions 22a, 22b extending along the lateral direction of the vehicle, and these torsion bar portions 21a, 21b. And a pair of arm portions 21c, 21d and arm portions 22c, 22d continuous to the torsion bar portions 22a, 22b. Here, the torsion bar portions 21a and 21b and the torsion bar portions 22a and 22b are supported with respect to the sprung member HA (vehicle body) so as to be rotatable around the axis thereof, and the arm portions 21c and 21d and the arm portions 22c and 22d are at the tips The portion is bent forward of the vehicle and connected to the lower arm of each suspension device 10.

  An electric actuator 21e and an electric actuator 22e are provided between the pair of torsion bar portions 21a and 21b in the front wheel side active stabilizer 21 and between the pair of torsion bar portions 22a and 22b in the rear wheel side active stabilizer 22, respectively. Yes. The electric actuators 21e, 22e are driven and controlled by an electric control device 40, which will be described later, and are anti-rolls applied to the sprung member HA (vehicle body) at the positions where the left and right front wheels FW1, FW2 and the left and right rear wheels RW1, RW2 are respectively positioned. Increase or decrease the moment. Therefore, for example, the electric actuators 21e and 22e appropriately change the torsional rigidity (torsional torque) of the torsion bar portions 21a, 21b, 22a, and 22b with respect to the roll moment that acts when the vehicle turns. An anti-roll moment that cancels the moment can be generated.

  The vehicle also includes a steering device 30 that steers the left and right front wheels FW1, FW2 and the left and right rear wheels RW1, RW2. The steering device 30 includes a steering handle 31 that is rotated by a driver to turn the vehicle. The steering handle 31 is fixed to the upper end of the steering shaft 32, and the lower end of the steering shaft 32 is connected to a turning gear unit 33 for turning the left and right front wheels FW1, FW2.

  Further, the steering device 30 includes a rear wheel steering unit 34 for turning the left and right rear wheels RW1, RW2 in relation to the steering of the left and right front wheels FW1, FW2. The rear wheel steering unit 34 includes an electric motor 34a and a rear wheel steering mechanism 34b that generate rotational driving force for steering the left and right rear wheels RW1 and RW2. The operation of the electric motor 34a is controlled by an electric control device 40 described later. The rear wheel steering mechanism 34b has a known gear mechanism, and decelerates the rotation of the electric motor 34a and converts the decelerated rotational motion into axial motion. The rear wheel steering mechanism 34 is connected to the left and right rear wheels RW1, RW2 via, for example, a toe control arm.

  With this configuration, the electric motor 34a is driven to rotate according to the turning operation of the steering handle 31 by the driver, that is, in accordance with the turning of the left and right front wheels FW1 and FW2, and the rotation decelerated by the rear wheel turning mechanism 34b. Converted to axial motion. Then, this axial movement is transmitted to the toe control arm, and the left and right rear wheels RW1, RW2 are steered left and right.

  Next, the electric control device 40 will be described. As shown in FIGS. 1 and 2, the electric control device 40 includes a suspension electronic control unit 41 (hereinafter simply referred to as a suspension ECU 41) that controls the operation of the actuator 11a of the suspension device 10 and the electric actuators 21e and 22e of the active stabilizer device 20. And a steering electronic control unit 42 (hereinafter simply referred to as a steering ECU 42) for controlling the operation of the electric motor 34a of the steering device 30. Here, the suspension ECU 41 and the steering ECU 42 are connected to each other via the communication line A.

  The suspension ECU 41 is a microcomputer whose main components are a CPU, a ROM, a RAM, and the like. The suspension ECU 41 executes various programs including a program to be described later, thereby controlling the operation of the actuator 11a to change and control the spring constant of the suspension spring 11, and also controls the operation of the electric actuators 21e and 22e. The torsional rigidity of the front wheel side active stabilizer 21 and the rear wheel side active stabilizer 22 is changed to change the magnitude of the anti-roll moment.

  The steering ECU 42 is also a microcomputer whose main components are a CPU, a ROM, a RAM, and the like. The steering ECU 42 executes various programs including a program to be described later, thereby controlling the operation of the electric motor 34a to steer the left and right rear wheels RW1 and RW2.

Therefore, the electric control device 40 includes a steering angle sensor 43, a rear wheel steering angle sensor 44, and a vehicle speed sensor 45. The steering angle sensor 43 detects the amount of turning operation of the steering handle 31, that is, the amount of rotation of the steering shaft 32, and outputs it as the steering angle θ. The steering angle sensor 43 outputs the rotation angle when the vehicle turns leftward as a positive value, and outputs the rotation angle when the vehicle turns rightward as a negative value. Are output as “0”, respectively. The rear wheel steering angle sensor 44 is assembled to the rear wheel steering mechanism 34 and detects, for example, a relative axial displacement of a rack bar constituting the mechanism 34 with respect to the vehicle body, and the detected relative axial direction. left and right rear wheels RW1 based on the displacement, and outputs the actual turning amount of RW2 as the rear wheel steering angle [delta] _r. The rear wheel steering angle sensor 45 outputs a steering amount when the left and right rear wheels RW1 and RW2 steer leftward with respect to the vehicle body as positive values, and steers when turning rightward. The amount is output as a negative value, and the turning amount when the vehicle maintains a straight traveling state is output as “0”. The vehicle speed sensor 45 detects and outputs the vehicle speed V of the vehicle.

  The sensors 43 to 45 are connected to the input sides of the suspension ECU 41 and the steering ECU 42 via the interface 46. On the other hand, a drive circuit 47 for controlling the operation of the actuator 11a is connected to the output side of the suspension ECU 41, and drive circuits 48a and 48b for controlling the operation of the electric actuators 21e and 22e, respectively. A drive circuit 49 for controlling the operation of the electric motor 34a is connected to the output side of the steering ECU 42.

  Next, the operation of the electric control device 40 configured as described above will be described in detail.

  When an ignition switch (not shown) is turned on by the driver, the electric control device 40, that is, the suspension ECU 41 and the steering ECU 42 cooperate with each other to execute the rear wheel steering control program shown in FIG. That is, the steering ECU 42 starts execution of the rear wheel steering control program in step S10, and inputs the steering angle θ of the steering wheel 31 from the steering angle sensor 43 and the vehicle speed V from the vehicle speed sensor 45 in step S11. To do. Then, the steering ECU 42 proceeds to step S12.

In step S12, the steering ECU 42 calculates a target rear wheel turning angle δ _rh of the left and right rear wheels RW1, RW2 to be steered in relation to the turning of the left and right front wheels FW1, FW2. Hereinafter, this calculation will be specifically described.

ただし、前記式１中のmは車両の慣性質量を表す。また、前記式１，２中のVは車速センサ４５によって検出された車速を表し、βは車両に発生した重心点位置における車体の横すべり角を表し、γは車両に発生したヨーレートを表す。また、前記式１，２中のL_fは車両重心点から前輪側車軸までの距離を表し、L_rは車両重心点から後輪側車軸までの距離を表す。また、前記式１，２中のK_fは前輪のコーナリングパワーを表し、K_rは後輪のコーナリングパワーを表す。また、前記式１，２中のδ_fは前輪の転舵角を表すものであり、後輪舵角センサ４４によって検出されたδ_rは後輪の転舵角を表す。さらに、前記式２中のIは車両のヨーイング慣性モーメントを表す。 In a vehicle in which the left and right front wheels FW1, FW2 and the left and right rear wheels RW1, RW2 can respectively be steered, if the four-wheel vehicle is an equivalent two-wheel vehicle, that is, a two-wheel vehicle model, The equation of motion shown by the following equations 1 and 2 is established.

However, m in the said Formula 1 represents the inertial mass of a vehicle. In the above formulas 1 and 2, V represents the vehicle speed detected by the vehicle speed sensor 45, β represents the side slip angle of the vehicle body at the position of the center of gravity generated in the vehicle, and γ represents the yaw rate generated in the vehicle. Further, L _f in the above formulas 1 and 2 represents the distance from the vehicle center of gravity to the front wheel side axle, and L _r represents the distance from the vehicle center of gravity to the rear wheel side axle. Further, K _f in the expressions 1 and 2 represents the cornering power of the front wheel, and K _r represents the cornering power of the rear wheel. Further, δ _f in the above formulas 1 and 2 represents the steering angle of the front wheel, and δ _r detected by the rear wheel steering angle sensor 44 represents the steering angle of the rear wheel. Further, I in Equation 2 represents the yawing moment of inertia of the vehicle.

ただし、前記式３中のθは操舵角センサ４３によって検出された操舵ハンドル３１（操舵入力軸３２）の操舵角を表す。また、前記式３中のnは転舵ギアユニット１３におけるステアリングギア比を表す。 Here, the turning angle δ _f of the front wheel can be expressed by the following Equation 3.

However, θ in Equation 3 represents the steering angle of the steering handle 31 (steering input shaft 32) detected by the steering angle sensor 43. Further, n in Equation 3 represents a steering gear ratio in the steered gear unit 13.

ここで、前記式４においては、その左辺が車両の運動を示しており、車両は右辺の任意に与えることができる操舵角θおよび左右後輪ＲＷ１，ＲＷ２の転舵角δ_rに応じて運動することが理解できる。 Then, when the equations 1 and 2 are transformed using the equation 3, the equation of motion of the vehicle can be expressed as the following equation 4. However, s in Formula 4 represents a Laplace operator.

Here, in the expression 4, the left side shows the movement of the vehicle, and the vehicle moves according to the steering angle θ that can be arbitrarily given on the right side and the turning angle δ _r of the left and right rear wheels RW1, RW2. I can understand.

In other words, at a certain vehicle speed V, assuming that the driver turns the steering wheel 11 to stabilize the behavior of the vehicle and turns, the yaw rate γ and the side slip angle β generated as the vehicle motion are A constant state is preferable. For this reason, in order to realize such a movement of the vehicle, the left side of Equation 4 is a constant. On the other hand, the steering angle θ on the right side of Equation 4 is determined by the turning operation of the steering handle 31 by the driver. For this reason, in order for the driver to turn the steering handle 31 to stabilize the behavior of the vehicle and to turn the vehicle, the turning angle δ _r of the left and right rear wheels RW1 and RW2 is determined so as to satisfy the above equation 4. do it.

Therefore, the steering ECU 42 sets the target turning angle δ of the left and right rear wheels RW1 and RW2 that establishes the expression 4 so that the yaw rate γ generated as the motion of the vehicle is constant and the side slip angle β is, for example, “0”. Calculate _rh . When the steering ECU 42 calculates the target turning angle δ _rh , the process proceeds to step S13.

  In step S13, the steering ECU 42 calculates an estimated roll angle φ predicted to be generated in the sprung member HA (vehicle body) by turning to the suspension ECU 41, and supplies the estimated roll angle φ. Request. The suspension ECU 41 calculates an estimated roll angle φ generated in the sprung member HA (vehicle body) according to the request received via the communication line A. Regarding the calculation of the estimated roll angle φ, since a well-known direction can be adopted, a detailed description thereof will be omitted, and a simple description will be given below.

ただし、前記式５中のK_φfは前輪側のロール剛性を表し、K_φrは前輪側のロール剛性を表す。また、前記式５中のh_sはバネ上部材（車体）の重心点とロール軸間の距離を表す。また、前記式５中のμW_sは、例えば、車速Vと操舵角θ（または時間微分した操舵速度θ’）に依存して車両に発生する横加速度を考慮したバネ上部材（車体）に働く慣性力を表す。 The (estimated) roll angle φ of the sprung member HA (vehicle body) generated with the turning can be generally calculated by the following equation (5).

However, K _.phi.f in formula 5 represents the roll stiffness on the front-wheel side, K _{[phi] r} represents the roll stiffness of the front wheel side. Further, h _{s in} Equation 5 represents a distance between the center of gravity of the sprung member (vehicle body) and the roll axis. In addition, μW _{s in} Equation 5 acts on a sprung member (vehicle body) that takes into account the lateral acceleration generated in the vehicle depending on, for example, the vehicle speed V and the steering angle θ (or the time-differentiated steering speed θ ′). Represents inertial force.

ただし、前記式６中のT_fは前輪側のトレッドを表し、前記式７中のT_rは後輪側のトレッドを表す。また、前記式６中のh_fは前輪側における地面からのロールセンタ高さを表し、前記式７中のh_rは後輪側後輪側における地面からのロールセンタ高さを表す。また、前記式６中のL_rは後輪側車軸と車両重心点間の距離を表し、前記式７中のL_fは前輪側車軸と車両重心点間の距離を表す。また、前記式６，７中のLは車両のホイールベース（L=L_f+L_r）を表す。 If the sprung member (vehicle body) rolls, load movement occurs, and for both the left and right front wheels FW1, FW2 and the left and right rear wheels RW1, RW2, the load increases on one of the left and right wheels, and the load decreases on the other. If this load movement amount is ΔW _f and ΔW _r respectively before and after, the following formulas 6 and 7 are established from the balance of moments around the roll center.

However, T _f in the expression 6 represents a tread on the front wheel side, and _Tr in the expression 7 represents a tread on the rear wheel side. Further, h _f in the expression 6 represents the roll center height from the ground on the front wheel side, and h _r in the expression 7 represents the roll center height from the ground on the rear wheel side rear wheel side. Further, L _r in the formula 6 represents the distance between the rear wheel axle and the vehicle center of gravity, L _f in the formula 7 is the distance between the front wheel axle and the vehicle center of gravity. Further, L in the equations 6 and 7 represents a vehicle wheel base (L = L _f + L _r ).

  When the suspension ECU 41 calculates the estimated roll angle φ generated in the vehicle body, the suspension ECU 41 supplies a signal representing the calculated estimated roll angle φ to the steering ECU 42. The steering ECU 42 receives the supplied signal and acquires an estimated roll angle φ generated in the vehicle body. Then, when the estimated roll angle φ is acquired, the steering ECU 42 proceeds to step S14.

In step S14, the steering ECU 42 reads a map representing a relationship between the target rear wheel turning angle δ _rh and the estimated roll angle φ shown in FIG. In subsequent step S15, the steering ECU 42 refers to the read map, and no interference occurs between the left and right rear wheels RW1, RW2 to be steered and the sprung member HA (vehicle body) that rolls. It is determined whether or not. That is, the steering ECU 42 acquires the target rear wheel turning angle δ _rh (absolute value) of the left and right rear wheels RW1, RW2 calculated in step S12 on the read map and the suspension ECU 41 in step S13. Whether or not the intersection point with the estimated roll angle φ is within an area that is equal to or less than a threshold value that is set so that no interference occurs between the left and right rear wheels RW1 and RW2 to be steered and the sprung member HA (vehicle body). Determine whether.

If the intersection is within the threshold value or less, no interference occurs between the left and right rear wheels RW1 and RW2 to be steered and the sprung member HA (vehicle body). Determination is made and the process proceeds to step S18 described later. In this case, since there is no interference between the left and right rear wheels RW1 and RW2 to be steered and the sprung member HA (vehicle body), the roll behavior of the sprung member (vehicle body) is suppressed as described later. Instead, the left and right rear wheels RW1, RW2 are steered to the target rear wheel turning angle δ _rh in step S18. On the other hand, as shown in FIG. 5, if the intersection does not exist within the threshold value or less, interference occurs between the left and right rear wheels RW1, RW2 to be steered and the sprung member HA (vehicle body). The steering ECU 42 determines “No” and proceeds to step S16.

In step S16, even if the steering ECU 42 steers the left and right rear wheels RW1 and RW2 to the target rear wheel turning angle δ _rh , there is interference between the left and right rear wheels RW1 and RW2 and the sprung member HA (vehicle body). A target roll angle φ _h that does not occur is determined. That is, as shown in FIG. 5, the steering ECU 42 determines a target roll angle φ _h that is equal to or less than the threshold value at the target rear wheel turning angle δ _rh . Then, steering ECU42, when determining the target roll angle φ _h, the process proceeds to step S17.

In step S17, the steering ECU42, to the suspension ECU 41, via the communication line A, the estimation of the sprung member HA (vehicle body) to supply a signal representative of the target roll angle phi _h determined at the step S16 A request is made to change the roll angle φ to the target roll angle φ _h . In response to this request, the suspension ECU 41 changes the estimated roll angle φ generated in the sprung member HA (vehicle body) to the target roll angle φ _h and the roll rigidity K _φf on the left and right front wheels FW1, FW2 side and the left and right rear Increase the roll rigidity K _φr on the side of the wheel RW1, RW2.

That is, the suspension ECU 41 substitutes the target roll angle φ _h represented by the supplied signal for the equations 6 and 7, and roll stiffness K _φf ′ on the left and right front wheels FW1 and FW2 side and left and right rear wheels RW1. , RW2 side roll stiffness K _φr ′ is calculated. The suspension ECU 41 sets a control constant for changing the spring constant of the suspension spring 11 in the suspension devices 10FR and 10FL in order to realize the _calculated roll rigidity K _φf ′ on the left and right front wheels FW1 and FW2. A control constant for changing the torsional rigidity of the front wheel side active stabilizer 21 of the active stabilizer device 20 is set. In addition, the suspension ECU 41 sets a control constant for changing the spring constant of the suspension spring 11 in the suspension devices 10RR and 10RL in order to realize the _calculated roll rigidity K _φr ′ on the left and right rear wheels RW1 and RW2. Then, a control constant for changing the torsional rigidity of the rear wheel side active stabilizer 22 of the active stabilizer device 20 is set.

Next, the suspension ECU 41 controls the operation of the actuator 11a, the electric actuator 21e, and the electric actuator 22e based on the set control constants. That is, the suspension ECU 41 operates the actuator 11a via the drive circuit 47 to increase the spring constant of the suspension spring 11 of the suspension devices 10FL, 10RL (or the suspension devices 10FR, 10RR) located on the outer side of the turn, and the anti-roll. Increase the moment. Further, the suspension ECU 41 operates the electric actuator 21e and the electric actuator 22e via the drive circuits 48a and 48b, thereby torsional rigidity of the torsion bar portions 21a and 22a (or the torsion bar portions 21b and 22b) located on the outer side of the turn. Increase to increase anti-roll moment. Thus, it is possible to suppress the rolling behavior of the sprung member (vehicle body) until the target roll angle phi _h. Therefore, interference between the left and right rear wheels RW1, RW2 to be steered and the sprung member (vehicle body) can be prevented. Then, when the operation control of the actuator 11a, the electric actuator 21e, and the electric actuator 22e is completed, the suspension ECU 41 outputs a completion signal indicating that the roll behavior suppression control is completed to the steering ECU 42 via the communication line A.

When the steering ECU 42 acquires the completion signal from the suspension ECU 41, the process proceeds to step S18. In step S18, the steering ECU 42 turns the left and right rear wheels RW1, RW2 to the target rear wheel turning angle δ _rh .

That is, the steering ECU 42 controls the drive circuit 49 without overshooting until the rear wheel turning angle δ _r detected by the rear wheel steering angle sensor 44 reaches the target turning angle δ _rh, and controls the electric motor 34 a. Drive to rotate. As a result, the rear wheel steering mechanism 34b decelerates the rotation of the electric motor 34a to convert it into an axial motion, and this axial motion is transmitted to the toe control arm. Therefore, the left and right rear wheels RW1, RW2 connected to the toe control arm are steered to the target turning angle δ _rh .

  As described above, when the left and right rear wheels RW1 and RW2 are steered, the steering ECU 41 proceeds to step S19 and temporarily terminates the execution of the rear wheel steering control program. And steering ECU42 starts execution of a rear-wheel steering control program again in step S10 after progress of predetermined short time.

As can be understood from the above description, according to the above embodiment, the left and right rear wheels RW1, RW2 and the sprung member (vehicle body) can be prevented from interfering with each other. Can be steered to a large target rear wheel turning angle δ _rh . Therefore, the left and right rear wheels RW1, RW2 can always be sufficiently steered, and the turning performance of the vehicle can be greatly improved.

  In carrying out the present invention, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the object of the present invention.

For example, in the above embodiment, in step S17 of the rear wheel steering control program, the suspension ECU 41 calculates roll stiffness K _φf ′ and K _φr ′ so that the sprung member (vehicle body) has the target roll angle φ _h. It was carried out to suppress the roll behavior. In this case, in order to prevent interference between the left and right rear wheels RW1 and RW2 to be steered and the sprung member (vehicle body), the suspension stroke of the suspension device 10 determined geometrically by the roll angle and the chassis geometry is set. It is also possible to control so as to suppress a decrease in vehicle height outside the turn. In this case, it is preferable to increase the damping force of the shock absorber 12 located outside the turning. Even in this case, the interference between the left and right rear wheels RW1 and RW2 and the sprung member (vehicle body) can be effectively prevented, and the left and right rear wheels RW1 and RW2 are moved to the target rear wheel turning angle δ _rh. Can be steered. Therefore, the left and right rear wheels RW1, RW2 can always be sufficiently steered, and the turning performance of the vehicle can be greatly improved.

  Further, in the above embodiment, the spring constant of the suspension spring 11 is changed and the torsional rigidity of the active stabilizers 21 and 22 is changed. In this case, it is possible to change the spring constant of the suspension spring 11 or the torsional rigidity of the active stabilizers 21 and 22.

FW1, FW2 ... front wheel, RW1, RW2 ... rear wheel, 10FL, 10FR, 10RL, 10RR ... suspension device, 11 ... suspension spring, 11a ... actuator, 12 ... shock absorber, 20 ... active stabilizer device, 21 ... front wheel side active stabilizer 21a, 21b ... Torsion bar section, 21e ... Electric actuator, 22 ... Rear wheel side active stabilizer, 22a, 22b ... Torsion bar section, 22e ... Electric actuator, 30 ... Steering device, 31 ... Steering handle, 32 ... Steering shaft, 33 ... steering gear unit, 34 ... rear wheel steering unit, 34a ... electric motor, 34b ... rear wheel steering mechanism, 40 ... electric control device, 41 ... suspension ECU, 42 ... steering ECU, 43 ... steering angle sensor, 44 ... Rear wheel rudder angle sensor 45 ... vehicle speed sensor, HA ... sprung member, LA ... unsprung member

Claims (1)

A vehicle control device mounted on a vehicle capable of front and rear wheel steering,
A rear wheel steering control means for calculating a target turning amount of the rear wheel of the vehicle in relation to the turning of the front wheel of the vehicle, and for controlling the turning of the rear wheel based on the target turning amount;
A roll amount representing the magnitude of the roll behavior generated in the sprung member of the vehicle as the vehicle turns is calculated, and the rear wheel steering control means applies the rear wheel to the target turning amount with respect to the calculated roll amount. Interference judging means for judging whether or not the rear wheel after the steering and the sprung member interfere when turning to
When it is determined by the interference determining means that the rear wheel after the steering interferes with the sprung member, at least the operation of the suspension device of the vehicle located outside the turn is controlled in order to avoid this interference. A vehicle control device comprising roll behavior suppression control means for suppressing the roll behavior.

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