JP2006082696A - Control device of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate the deterioration of the steering feeling resulting from a change in the characteristics of a suspension control device. <P>SOLUTION: An ECU 35 for assisting the steering calculates the controlling amount Tas-Tav on the basis of the vehicle speed V and the steering angular velocity θv and gives an assist torque corresponding to the controlling amount Tas-Tav to the turning operation of a steering wheel 11 by operating an electric motor 15 under control in accordance with the controlling amount Tas-Tav. An ECU 36 for stabilizers rotates stabilizers 21 and 22 so that the relative rotating angle lessens by operating an electric motor 25 under control in accordance with the relative rotating angle of the stabilizers 21 and 22. When the stabilizer control system is in failure, the ECU 35 sets small the damping controlling amount Tav to compensate the increase of the damping coefficient for the rotary motion round a king pin shaft in association with the failure. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a vehicle control device including a suspension control device and a steering control device, and more particularly to a vehicle that changes and controls the assist force for the steering operation of the steering wheel by the steering control device in accordance with the control state of the suspension control device. The present invention relates to a control device.

2. Description of the Related Art Conventionally, as shown in, for example, Patent Document 1 below, an assist force for a steering operation of a steering wheel by a steering control device is changed and controlled according to a control state of a damping force of a shock absorber by a suspension control device. Control devices are known.
Japanese Patent Publication No. 63-120002

  However, in the above-mentioned conventional device, no consideration is given to the change in the damping characteristic of the steering system that greatly affects the steering feeling of the steering wheel due to the change in the damping force of the shock absorber, that is, the change in the characteristics of the suspension control device. It has not been. As a result, there is a problem that the steering feeling deteriorates when the characteristics of the suspension control device change.

  The present invention has been made to address the above-described problems, and an object of the present invention is to provide a vehicle control device that eliminates the deterioration of steering feeling caused by changes in the characteristics of the suspension control device.

  In order to achieve the above object, the present invention is characterized in that in a vehicle control device including a suspension control device and a steering control device, turning of steered wheels according to a steering operation of a steering wheel is performed in the steering control device. An assisting electric actuator, a steering torque detecting means for detecting a steering torque applied to the steering handle, an assist torque determining means for determining an assist torque that changes in accordance with the detected steering torque, and a steering angular velocity of the steering handle A steering angular velocity detection means for detecting a damping control amount, a damping control amount determination means for determining a damping control amount that changes according to the detected steering angular velocity and changes according to the control state of the suspension control device, and the determined assist The electric actuator is controlled in accordance with a control amount obtained by adding the determined attenuation control amount to the torque. The in providing the driving control means for controlling driving.

  When the control state of the suspension control device changes, the damping coefficient for the rotational motion around the kingpin axis of the steered wheels changes. In the present invention configured as described above, the damping control amount determining means determines the damping control amount that changes according to the control state of the suspension control device, and the drive control means determines this damping control amount according to the steering torque. The electric actuator is controlled in consideration of the assist torque. As a result, according to the present invention, it is possible to eliminate the influence on the steering feeling of the steering wheel due to the change in the attenuation coefficient, and the driver can perform the steering operation with a good steering feeling.

  A feature of the present invention more specifically described above is that an abnormality detecting means for detecting an abnormality of the suspension control apparatus is provided in the suspension control apparatus, and the damping control amount determining means detects an abnormality of the suspension control apparatus by the abnormality detecting means. The attenuation control amount that changes according to the steering angular velocity is set to a different value depending on whether it is detected or not. In this case, for example, the abnormality detection means detects an abnormality of the stabilizer control device for controlling the twisting force of the stabilizer bar provided in the suspension control device to suppress the roll of the vehicle, and determines the damping control amount. When the abnormality detecting means detects an abnormality of the stabilizer control device, the attenuation control amount is set to a damping coefficient for the rotational motion around the kingpin axis of the steered wheel associated with the abnormality compared to when the abnormality is not detected. A compensation control amount for compensating for the change or a value changed by a control amount larger than the compensation control amount is set.

  When the stabilizer control device is abnormal, the torsional force of the stabilizer bar cannot be controlled. Therefore, the steering characteristics of the vehicle are higher when the vehicle is turning than when the stabilizer torsional force is controlled. Therefore, the damping coefficient for the rotational motion around the kingpin axis of the steered wheels increases. On the other hand, in this specific invention, the damping control amount that changes according to the steering angular velocity is set to a different value when the abnormality of the suspension control device is detected and when it is not detected. As a result, it is possible to eliminate the influence on the steering feeling of the steering wheel due to the change of the attenuation coefficient due to the abnormality of the stabilizer control device, and the driver can perform the steering operation of the steering wheel with a good steering feeling.

  In particular, when an abnormality of the stabilizer control device is detected, if the attenuation control amount is set to a value changed by the compensation control amount compared to when the abnormality is not detected, it is completely the same as when the stabilizer control device is normal. The steering wheel can be steered with the same steering feeling. Further, if the attenuation control amount is set to a value changed by a control amount larger than the compensation control amount when an abnormality of the stabilizer control device is detected, compared to when the abnormality is not detected, the stabilizer control device The steering feeling is not exactly the same as normal, but the influence on the steering feeling of the steering wheel due to the change of the damping coefficient due to the abnormality of the stabilizer control device is reduced, and the change of the steering feeling gives the driver Vehicle abnormality can be recognized.

  In another aspect of the invention embodying the present invention, the suspension control device includes damping force control means for changing and controlling the damping force by the shock absorber. Then, the damping control amount determining means sets the damping control amount when the damping force of the shock absorber is high compared to when the damping force is low, with respect to the rotational motion around the kingpin axis of the steered wheels as the damping force increases. The compensation control amount for compensating for the change of the attenuation coefficient or a value changed by a control amount larger than the compensation control amount is set. In this case, when the damping force of the shock absorber is large, the damping control amount is set to a smaller value than when the damping force is small.

  When the damping force of the shock absorber is increased, the delay in generating the cornering force due to the roll response of the vehicle is suppressed, so that the damping coefficient for the rotational motion around the kingpin axis of the steered wheels increases. On the other hand, in this specific invention, when the damping control amount that changes according to the steering angular velocity is high, the compensation control amount or the above-described amount of damping control is greater when the damping force of the shock absorber is high than when the damping force is low. It is set to a value changed by a control amount larger than the compensation control amount. As a result, it is possible to eliminate the influence on the steering feeling of the steering wheel due to the change of the damping coefficient accompanying the change of the damping force of the shock absorber, and the driver can steer the steering wheel with a good steering feeling. . In particular, if the damping control amount is set to a value changed by the compensation control amount when the damping force of the shock absorber is high compared to when the damping force is low, even if the damping force of the shock absorber is changed. The steering handle can always be steered with the same steering feeling. In addition, when the damping control amount is set to a value that is changed by a control amount larger than the compensation control amount when the damping force of the shock absorber is high compared to when the damping force is low, the same steering feeling is obtained. However, it is possible to obtain a driving characteristic showing a change in the same direction as a change in the driving characteristic of the vehicle obtained by switching the damping force, and the driver's intention is reflected. That is, when the damping force is changed from a small value to a large value (when the damping force is changed from a luxury to a sporty state), damping of the steering system is suppressed and a fast response steering transmission characteristic is realized.

  Another feature of the invention embodying the present invention includes vehicle height control means for the suspension control device to change and control the vehicle height. When the vehicle height is high, the damping control amount determining means changes the damping coefficient with respect to the rotational motion around the kingpin axis of the steered wheels as the vehicle height increases, compared to when the vehicle height is low. Is set to a value changed by a compensation control amount for compensating for or a control amount larger than the compensation control amount. In this case, when the vehicle height is high, the attenuation control amount is set to a smaller value than when the vehicle height is low.

  When the vehicle height increases, the steering characteristic of the vehicle becomes understeer due to an increased roll when the vehicle turns, so that the damping coefficient for the rotational motion around the kingpin axis of the steered wheels increases. On the other hand, in this specific invention, the attenuation control amount that changes in accordance with the steering angular velocity is higher when the vehicle height is higher than when the vehicle height is low. A value that is changed by a larger control amount is set. As a result, the influence on the steering feeling of the steering wheel due to the change in the vehicle height can be eliminated, and the driver can steer the steering wheel with a good steering feeling. In particular, if the damping control amount is set to a value changed by the compensation control amount when the vehicle height is high compared to when the vehicle height is low, the same steering feeling is always maintained even if the vehicle height is changed. The steering handle can be steered. Further, when the damping control amount is set to a value that is changed by a control amount that is larger than the compensation control amount when the vehicle height is high compared to when the vehicle height is low, the steering feeling is not the same. The driver can be made aware of the stability of the vehicle corresponding to the vehicle height state through the steering of the vehicle. In other words, the vehicle is unstable when the vehicle height is high, and the damping of the steering system is reduced by changing the control amount that is larger than the compensation control amount. It can be recognized that it is stable.

a. First Embodiment Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a vehicle control apparatus according to the first embodiment. The vehicle control device includes a steering control device and a stabilizer control device as a suspension control device.

  The steering control device includes a steering shaft 12 connected to the steering handle 11 so as to rotate integrally at its upper end, and a pinion gear 13 is connected to the lower end of the shaft 12 so as to rotate integrally. The pinion gear 13 meshes with rack teeth formed on the rack bar 14 to constitute a rack and pinion mechanism. The left and right front wheels FW1, FW2 are steerably connected to both ends of the rack bar 14, and the left and right front wheels FW1, FW2 are moved to the left and right according to the axial displacement of the rack bar 14 as the steering shaft 12 rotates about the axis. Steered. The rack bar 14 is assembled with an electric motor 15 as an electric actuator for steering assist. The rotation of the electric motor 15 is decelerated by the ball screw mechanism 16 constituting the speed reducer and converted into a linear motion of the rack bar 14.

  The stabilizer control device includes stabilizer bars 21 and 22 that are divided into two. The stabilizer bars 21 and 22 are assembled to the left and right front wheels FW1 and FW2 via the wheel-side members at the respective outer end portions, and rotate about the axis of the vehicle body BD via the bearings 23 and 24 at the respective intermediate portions. It is assembled as possible. Then, the stabilizer bars 21 and 22 function to eliminate the twist generated with the roll of the vehicle and suppress the roll of the vehicle.

  An electric motor 25 and a speed reduction mechanism 26 as electric actuators are interposed between the stabilizer bars 21 and 22. The inner end of the stabilizer bar 21 is connected to the stator of the electric motor 25, and the inner end of the stabilizer bar 22 is connected to the output shaft of the speed reduction mechanism 26. Accordingly, the electric motor 25 causes the stabilizer bar 22 to rotate relative to the stabilizer bar 21 around the axis line via the speed reduction mechanism 26 by the rotation.

  Next, an electric control device that controls the operation of the electric motors 15 and 25 will be described. The electric control device includes a steering torque sensor 31, a steering angle sensor 32, a vehicle speed sensor 33, and a rotation angle sensor 34. The steering torque sensor 31 is assembled to the upper part of the steering shaft 12 and detects the steering torque Tr acting on the steering shaft 12 by the turning operation of the steering handle 11. The steering angle sensor 32 is assembled to the upper part of the steering shaft 12 and detects the steering angle θ of the steering handle 11. Note that the steering torque Tr and the steering angle θ represent the steering torque and the steering angle when the steering handle 11 is steered in the right direction and the left direction, respectively, with positive and negative values. The vehicle speed sensor 33 detects and outputs the vehicle speed V. The rotation angle sensor 34 is assembled to the electric motor 25 and detects the relative rotation angle α generated between the stabilizer bars 21 and 22 with twisting by measuring the rotation angle of the electric motor 25.

  The electric control device is connected to a steering assist electronic control unit (hereinafter simply referred to as a steering assist ECU) 35 connected to a steering torque sensor 31, a steering angle sensor 32, and a vehicle speed sensor 33, and a rotation angle sensor 34. And a stabilizer electronic control unit (hereinafter simply referred to as “stabilizer ECU”) 36. The steering assist ECU 35 and the stabilizer ECU 36 are connected to each other, and each of them includes a microcomputer including a CPU, a ROM, a RAM, and the like as main components. The steering assist ECU 35 controls the drive of the electric motor 15 via the drive circuit 37 by executing the assist control program shown in FIG. The stabilizer ECU 36 controls the drive of the electric motor 25 via the drive circuit 38 by executing the stabilizer control program of FIG. The drive circuits 37 and 38 flow drive currents designated by the steering assist ECU 35 and the stabilizer ECU 36 to the electric motors 15 and 25, respectively.

  Next, the operation of the embodiment configured as described above will be described. By turning on an ignition switch (not shown), the steering assist ECU 35 and the stabilizer ECU 36 start to repeatedly execute the assist control program and the stabilizer control program every predetermined short time. The execution of the assist control program is started in step S10 in FIG. 2, and the steering torque Tr, the steering angle θ, and the vehicle speed V are input from the steering torque sensor 31, the steering angle sensor 32, and the vehicle speed sensor 33 in step S11, respectively. Further, the steering assist ECU 35 also inputs a fail flag FAL from the stabilizer ECU 36 in step S11. The fail flag FAL indicates the stabilizer control operating state by the electric motor 25 by “0”, and the stabilizer control stop state by “1” due to an abnormality in the electric motor 25 or the like. Next, the steering assist ECU 35 calculates the steering angular velocity θv (= dθ / dt) by differentiating the steering angle θ in step S12.

  After the processing of step S12, the steering assist ECU 35 calculates an assist torque Tas that changes in accordance with the steering angle θ and the vehicle speed V with reference to an assist command value table provided in the ROM in step S13. To do. As shown in FIG. 4, the assist command value table stores a plurality of assist torques Tas that increase nonlinearly as the steering torque Tr increases for each of a plurality of representative vehicle speed values. The assist torque Tas is larger as the vehicle speed V is lower than the same steering torque Tr. Instead of using this assist torque table, the assist torque Tas that changes according to the steering torque Tr and the vehicle speed V is defined in advance using a function, and the assist torque Tas is calculated using the function. It may be. The assist torque Tas is basically determined by the steering torque Tr. Since the vehicle speed V is an auxiliary factor, the assist torque Tas depends on only the steering torque Tr, ignoring changes in the vehicle speed V. You may make it decide.

  After step S13, the steering assist ECU 35 determines in step S14 whether or not the input fail flag FAL is “0”. First, the case where the fail flag FAL is “0” and the stabilizer control by the electric motor 25 is executed as described later will be described. Accordingly, in this case, “Yes” is determined in step S14, and the program proceeds to step S15.

  In step S15, the steering assist ECU 35 refers to the first damping control amount table provided in the ROM, calculates the first damping control amount Tav1 that changes according to the steering angular velocity θv, and performs damping control. Set as quantity Tav. The first attenuation control amount table stores a first attenuation control amount Tav1 that increases as the steering angular velocity θv increases, as indicated by a solid line in FIG. Instead of using the first damping control amount table, the first damping control amount Tav1 that changes according to the steering angular velocity θv is defined in advance by a function, and the first damping control is made using the same function. Tav1 may be calculated.

  Next, in step S17, the steering assist ECU 35 uses the control amount Tas-Tav obtained by subtracting the attenuation control amount Tav from the calculated assist torque Tas in cooperation with the drive circuit 37 to control the amount Tas- The electric motor 15 is driven and controlled so that a torque equal to Tav is generated. Then, the steering assist ECU 35 once terminates the execution of the assist control program in step S18. Thereby, the electric motor 15 outputs a rotational torque equal to the control amount Tas-Tav to its output shaft. This rotational torque is transmitted to the ball screw mechanism 16, which decelerates the rotation of the electric motor 15 and converts it into linear motion to drive the rack bar 14 in the axial direction. As a result, the turning operation of the steering handle 11 by the driver is assisted by the electric motor 15, and the left and right front wheels FW 1 and FW 2 are steered by the steering force by the driver and the assist force by the electric motor 15.

  On the other hand, the stabilizer ECU 36 also repeatedly executes the stabilizer control program every predetermined short time in parallel with the assist control program. The execution of the stabilizer control program is started in step S20 of FIG. 3, and the stabilizer ECU 36 inputs a signal from the drive circuit 38 in step S21, and causes the stabilizer control system such as disconnection or short circuit of the electric motor 25 to the stabilizer control system. Inspect for abnormalities. In step S22, it is determined whether or not an abnormality has been detected based on this inspection. As described above, when the description continues for the case where no abnormality has occurred in the stabilizer control system, the stabilizer ECU 36 determines “No” in step S22 and advances the program to step S23.

  In step S <b> 23, the stabilizer ECU 36 inputs the relative rotation angle α from the rotation angle sensor 34. Then, in step S24, the stabilizer ECU 36 cooperates with the drive circuit 38 to generate a rotational torque in a direction proportional to the relative rotational angle α and decreasing the relative rotational angle α. Is controlled. The electric motor 25 applies the rotational torque between the stabilizer bars 21 and 22 via the speed reduction mechanism 26 in a direction that eliminates the relative rotation generated between the stabilizer bars 21 and 22 due to the twisting of the stabilizer bars 21 and 22. To do. As a result, the stabilizer bars 21 and 22 suppress rolling caused by turning of the vehicle.

  After the process of step S24, the stabilizer ECU 36 sets the fail flag FAL to “0” in step S25. Then, the stabilizer ECU 36 outputs the fail flag FAL set to “0” to the steering assist ECU 35 in step S28, and temporarily ends the execution of the stabilizer control program in step S29.

  Next, a case where an abnormality occurs in the stabilizer control system will be described. In this case, the stabilizer ECU 36 determines “Yes” in step S22, that is, an abnormality has occurred in the stabilizer control system, and advances the program to step S26. In step S <b> 26, the stabilizer ECU 36 controls to stop the operation of the electric motor 25. Thereby, since the electric motor 25 stops the rotational drive control of the stabilizer bars 21 and 22 that suppress the relative rotation angle α generated between the stabilizer bars 21 and 22, the restraining force on the roll of the vehicle is reduced. Since the steering characteristic is understeered by an increase in the roll of the vehicle, the damping coefficient with respect to the rotational motion around the kingpin axis of the left and right front wheels FW1 and FW2 is the rotation of the stabilizer bars 21 and 22 shown by the solid line in FIG. Compared to the drive control, it increases as shown by the broken line in FIG.

  After the process of step S26, the stabilizer ECU 36 sets the fail flag FAL to “1” in step S27, and outputs the fail flag FAL set to “1” to the steering assist ECU 35 in step S28. In step S29, the execution of the stabilizer control program is temporarily terminated.

  When the abnormality occurs in the stabilizer control system and the fail flag FAL set to “1” is output to the steering assist ECU 35, the steering assist ECU 35 determines “No” in step S14 of FIG. Then, the process of step S16 is executed.

  In step S16, the steering assist ECU 35 refers to the second attenuation control amount table provided in the ROM, calculates the second attenuation control amount Tav2 that changes according to the steering angular velocity θv, and performs attenuation control. Set as quantity Tav. The second attenuation control amount table stores a second attenuation control amount Tav1 that increases as the steering angular velocity θv increases, as indicated by a broken line in FIG. This second damping control amount Tav2 is shown by a solid line in FIG. 5 in order to compensate for the increased damping coefficient (see FIG. 6A) when driving control of the stabilizer bars 21 and 22 by the electric motor 25 is stopped. The absolute value is set to a smaller value by an amount corresponding to the increased attenuation coefficient than the first attenuation control amount Tav1. Instead of using the second damping control amount table, a second damping control amount Tav2 that changes according to the steering angular velocity θv is defined in advance by a function, and the second damping control is made using the same function. Tav2 may be calculated.

  After the process of step S16, the steering assist ECU 35 uses the control amount Tas-Tav obtained by subtracting the attenuation control amount Tav (= Tav2) from the calculated assist torque Tas by the process of step S17 described above. , And the electric motor 15 is caused to generate a rotational torque equal to the control amount Tas-Tav. Then, the rotation operation of the steering handle 11 by the driver is assisted by this rotational torque. As described above, since the second damping control amount Tav2 is set to a smaller value in absolute value than the first damping control amount Tav1, the assist amount for the turning operation of the steering handle 11 is determined by the electric motor 25. It increases compared with the case where the stabilizer bars 21 and 22 are driven and controlled.

  As described in the above description of the operation, in the first embodiment, when an abnormality occurs in the stabilizer control system and the drive control of the stabilizer bars 21 and 22 by the electric motor 25 is stopped, the steering characteristic of the vehicle is Compared to the drive control of the stabilizer bars 21 and 22 by the electric motor 25, the vehicle becomes easier to roll, resulting in understeer, and the damping coefficient for the rotational motion around the kingpin axis of the left and right front wheels FW1 and FW2 increases. That is, the attenuation coefficient changes from a solid line to a broken line in FIG. In this case, according to the first embodiment, the attenuation control amount Tav that changes according to the steering angular velocity θv by the process of step S16 in FIG. 2 is compared with that during the drive control of the stabilizer bars 21 and 22 by the electric motor 25. The absolute value of the compensation control amount for compensating for the change in the attenuation coefficient is set to a small value. That is, the attenuation control amount Tav changes from a solid line to a broken line in FIG. As a result, the damping control amount Tav in the steering assist control decreases as shown by the broken line in FIG. 6B, and the overall friction coefficient including the steering system friction is included in the damping coefficient and the damping control amount Tav. As indicated by the solid line in FIG. 6 (C), it is the same when the stabilizer control system is abnormal and when it is normal. Accordingly, it is possible to eliminate the influence on the steering feeling of the steering handle 11 due to the change of the attenuation coefficient due to the abnormality of the stabilizer control device, and the steering handle 11 can be steered with the same steering feeling as when the stabilizer control system is normal. .

  In the first embodiment, when the drive control of the stabilizer bars 21 and 22 by the electric motor 25 is stopped, the attenuation control amount Tav is further increased in absolute value compared to the drive control of the stabilizer bars 21 and 22 by the electric motor 25. You may make it control small. That is, when an abnormality of the stabilizer control system is detected, the attenuation control amount Tav may be set to a value changed by a control amount larger than the compensation control amount, compared to when the abnormality is not detected. .

  In this case, the steering assist ECU 35 changes according to the steering angular velocity θv with reference to the third attenuation control amount table provided in the ROM, as shown in parentheses in step S16 of FIG. The third attenuation control amount Tav3 may be calculated and set as the attenuation control amount Tav. The This third damping control amount table stores a third damping control amount Tav3 that increases as the steering angular velocity θv increases, as indicated by a one-dot chain line in FIG. The third damping control amount Tav3 is set to a smaller value in absolute value than the second damping control amount Tav2 indicated by a broken line in FIG. 5 with respect to the same steering angular velocity θv. In this case, instead of using the third damping control amount table, the third damping control amount Tav3 that changes according to the steering angular velocity θv is defined in advance by a function, and the third function is used by using the function. You may make it calculate 3 attenuation | damping control Tav3.

  According to this modification, the damping control amount Tav in the steering assist control is shown by a one-dot chain line in FIG. 6B, and the total friction including the steering system friction is included in the damping coefficient and damping control amount Tav. The coefficient is smaller than that in the normal state of the stabilizer control system described above, as indicated by a one-dot chain line in FIG. Therefore, the driver can turn the steering handle 11 with a smaller steering force. On the other hand, in this case, the vehicle changes to an unstable side, and the vehicle becomes unstable especially when the steering handle 11 is largely steered. As a result, the driver recognizes the abnormality of the vehicle by the change of the steering feeling.

b. Second Embodiment Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 7 shows a vehicle control apparatus according to the second embodiment. The vehicle control device includes a damping force control device that controls a damping force by a shock absorber as a suspension control device, instead of the stabilizer control device of the first embodiment. Also in this second embodiment, the steering control device including the electric control device is configured in the same manner as in the first embodiment, but the steering assist ECU 35 in the steering control device executes the assist control program of FIG. The electric motor 15 is driven and controlled.

  The damping force control device is provided with a shock absorber 40 and a coil spring 50 as shown in the figure representatively of only one of the front, rear, left and right four wheels. The shock absorber 40 is interposed between an unsprung member LA such as a lower arm and a knuckle connected to the wheel W and a vehicle body BD (sprung member), and is attached to the unsprung member LA at the lower end of the cylinder 41. It is connected to the vehicle body BD at the upper end of a piston rod 42 that is connected to the cylinder 41 so as to be movable up and down. The coil spring 50 is provided in parallel with the shock absorber 40. The cylinder 41 is divided into upper and lower chambers by a piston 43 that slides liquid-tightly on the inner peripheral surface thereof. A variable throttle device 44 incorporating an electric actuator is assembled to the piston 43. The variable throttle device 44 switches the opening degree of the communication path that communicates between the upper and lower chambers of the cylinder 41.

  Next, an electric control device that drives and controls the variable aperture device 44 will be described. The electric control device includes a changeover switch 61 for selecting the shock absorber 40 as one of software and hardware. The changeover switch 61 is connected to an absorber electronic control unit (hereinafter simply referred to as an absorber ECU) 62. The absorber ECU 62 is also connected to the steering assist ECU 35 and includes a microcomputer including a CPU, a ROM, a RAM, and the like as main components. The absorber ECU 62 executes a damping force control program (not shown) to selectively switch the damping force of the shock absorber 40 softly or hardly by switching the opening degree of the communication passage of the variable throttle device 44 via the drive circuit 63. Switch to.

  In the second embodiment configured as described above, if the driver operates the changeover switch 61 to select software, the absorber ECU 62 controls the variable throttle device 44 in cooperation with the drive circuit 63. Thus, the opening degree of the communication passage for communicating between the upper and lower chambers of the cylinder 41 is set large. Thereby, the damping force of the shock absorber 40 is set to be soft. If the driver operates the changeover switch 61 to select hardware, the absorber ECU 62 controls the variable throttle device 44 in cooperation with the drive circuit 63 to communicate between the upper and lower chambers of the cylinder 41. Set the passage opening small. Thereby, the damping force of the shock absorber 40 is set to the hard side. A selection signal indicating the selection state of the soft and hard damping force is output to the steering assist ECU 35.

  In parallel with the control of the damping force of the shock absorber 40, the steering assist ECU 35 repeatedly executes the assist control program of FIG. 8 every predetermined short time. The assist control program of FIG. 8 is obtained by changing the processes of steps S11 and S14 of the assist control program of FIG. 2 according to the first embodiment to processes of steps S31 and S32. In step S31, a damping force selection signal is input from the absorber ECU 62 instead of the input of the fail flag FAL of the first embodiment. The point that the steering torque Tr, the steering angle θ, and the vehicle speed V are input is the same as in the case of the first embodiment.

  Then, the steering assist ECU 35 determines in step S32 whether the input damping force selection signal represents software or hardware. If the damping force selection signal represents software, the steering assist ECU 35 determines “Yes” in step S32 and executes the processes of steps S15 and S17 similar to those in the above embodiment. As a result of the processing in steps S15 and S17, the control amount Tas−Tav (subtracting the first damping control amount Tav1 determined in accordance with the steering angular velocity θv from the assist torque Tas determined in accordance with the steering torque Tr and the vehicle speed V). Assist torque corresponding to = Tas−Tav1) is applied to the turning operation of the steering handle 11.

  If the damping force selection signal indicates hardware, the steering assist ECU 35 determines “No” in step S32, and executes the processes of steps S16 and S17 similar to those in the above embodiment. As a result of the processing in steps S16 and S17, the control amount Tas-Tav (subtracting the second damping control amount Tav2 determined according to the steering angular velocity θv from the assist torque Tas determined according to the steering torque Tr and the vehicle speed V ( Assist torque corresponding to = Tas−Tav2) is applied to the turning operation of the steering handle 11. However, the second damping control amount Tav2 compensates for an increase in the damping coefficient with respect to the rotational motion around the kingpin axis of the left and right front wheels FW1 and FW2 by increasing the damping force of the shock absorber 40, as compared with the first damping control amount Tav1. The absolute value is small as much as possible.

  In such a vehicle control apparatus according to the second embodiment, when the damping force of the shock absorber 40 is switched from soft to hard, the generation delay of the cornering force of the left and right front wheels FW1, FW2 due to the roll response of the vehicle is suppressed. The damping coefficient for the rotational motion around the kingpin axis of the left and right front wheels FW1, FW2 increases as shown by the change from the solid line to the broken line in FIG. On the other hand, as described above, the damping control amount Tav in the steering assist is changed from the first damping control amount Tav1 to the second damping control amount Tav2 in conjunction with the switching of the damping force (the solid line and the broken line in FIG. 5). See). That is, when the damping force of the shock absorber 40 becomes hard, the damping control amount Tav in the steering assist is set to a value having a smaller absolute value than in the case where the damping force of the shock absorber 40 is soft.

  Accordingly, even if the damping force of the shock absorber 40 is switched from soft (low side) to hard (high side), the damping control amount Tav in the steering assist is changed to the left and right front wheels FW1, FW2 accompanying the change of the damping force of the shock absorber 40. As shown by the change from the solid line to the broken line in FIG. 9B, the value is changed from a large value to a small value by the increase in the damping coefficient with respect to the rotational motion around the kingpin axis. As shown by a solid line in FIG. 9C, the overall friction coefficient including the steering system friction is included in the damping coefficient and the damping control amount Tav even if the damping force of the shock absorber 40 changes. Become. As a result, it is possible to eliminate the influence on the steering feeling of the steering handle 11 due to the change in the damping coefficient accompanying the change in the damping force of the shock absorber 40, and the driver always steers the steering handle 11 with the same steering feeling. it can.

  In the second embodiment, when the damping force of the shock absorber 40 is set to be hard (on the higher side), the damping control amount Tav may be controlled to be smaller in absolute value. In this case, the steering assist ECU 35 changes according to the steering angular velocity θv with reference to the third attenuation control amount table provided in the ROM, as shown in parentheses in step S16 of FIG. The third attenuation control amount Tav3 may be calculated and set as the attenuation control amount Tav. The third damping control amount Tav3 is set to a smaller value in absolute value than the second damping control amount Tav2 with respect to the same steering angular velocity θv (see FIG. 5).

  According to this modification, the damping control amount in the steering assist is further smaller than that of the broken line as shown by the one-dot chain line in FIG. 9B, and the steering system friction is reduced to the damping coefficient and damping control amount Tav. As shown by the alternate long and short dash line in FIG. 9 (C), the overall friction coefficient including is further smaller than in the case of the second embodiment. As a result, a driving characteristic showing a change in the same direction as the change in the driving characteristic of the vehicle obtained by switching the damping force of the shock absorber 40 can be obtained, and the driver's intention is reflected. In other words, when the damping force of the shock absorber 40 is changed from a small value to a large value (from a luxury to a sporty state), steering system damping is suppressed and a quick response steering transmission characteristic is realized. The

  Further, in the second embodiment, the damping force of the shock absorber 40 is switched between two stages of software and hardware. However, the damping force may be switched between three or more stages. In this case, as the damping force is switched from the soft side (small side) to the hard side (large side), the damping control amount Tav in the steering assist may be set to a value with a small absolute value. Further, as shown by a broken line in FIG. 7, a motion state quantity sensor 64 for detecting a motion state quantity of the vehicle such as a vehicle speed, a longitudinal acceleration, a yaw rate, a lateral acceleration, and a roll is provided. The damping force of the shock absorber 40 may be switched and controlled according to the amount of motion state of the vehicle detected by. Also in this case, the absorber ECU 62 outputs a damping force selection signal indicating the switching state of the damping force of the shock absorber 40 to the steering assist ECU 35. The steering assist ECU 35 may set the damping control amount Tav in the steering assist to a small absolute value as the damping force of the shock absorber 40 represented by the supplied damping force selection signal increases.

c. Third Embodiment Next, a third embodiment of the present invention will be described with reference to the drawings. FIG. 10 shows a vehicle control apparatus according to the third embodiment. This vehicle control device includes a vehicle height control device as a suspension control device instead of the stabilizer control device of the first embodiment. Also in this third embodiment, the steering control device including the electric control device is configured in the same manner as in the first embodiment, but the steering assist ECU 35 in the steering control device executes the assist control program of FIG. The electric motor 15 is driven and controlled.

  In the vehicle height control device, an air chamber 71 and a shock absorber 72 are interposed between the wheel W and the vehicle body BD, as shown as representative of only one of the front, rear, left, and right four wheels. An air supply / discharge device 73 including an electric pump, a supply / discharge valve, and the like is connected to the air chamber 71, and the vehicle height is changed by supplying / discharging air to / from the air chamber 71.

  Next, an electric control device that controls the air supply / discharge device 73 will be described. The electric control device includes a changeover switch 74 and a vehicle height sensor 75. The changeover switch 74 is operated by the driver to select the vehicle height as either low or high. The vehicle height sensor 75 detects the height of the vehicle body BD at the wheel W position from the road surface (that is, the vehicle height). The changeover switch 74 and the vehicle height sensor 75 are connected to a vehicle height electronic control unit (hereinafter simply referred to as vehicle height ECU) 76. The vehicle height ECU 76 is also connected to the steering assist ECU 35, and includes a microcomputer including a CPU, a ROM, a RAM, and the like as main components. The vehicle height ECU 76 executes a vehicle height control program (not shown) to control the air supply / discharge device 73 via the drive circuit 77 to selectively switch the vehicle height to low or high.

  In the third embodiment configured as described above, if the driver operates the changeover switch 74 to select low, the vehicle height ECU 76 corresponds to the vehicle height detected by the vehicle height sensor 75 being low. The air supply / discharge device 73 is controlled so as to be a value. Specifically, the air supply / discharge device 73 is controlled via the drive circuit 77 to discharge the air in the air chamber 71 so that the vehicle height detected by the vehicle height sensor 75 becomes a value corresponding to low. Reduce the vehicle height. If the driver operates the changeover switch 74 to select high, the vehicle height ECU 76 controls the air supply / discharge device 73 via the drive circuit 77 to supply air to the air chamber 71, The vehicle height is raised until the vehicle height detected by the high sensor 75 reaches a value corresponding to high. Further, the vehicle height ECU 76 outputs a vehicle height selection signal indicating low or high of the vehicle height to the steering assist ECU 35.

  In parallel with the vehicle height control, the steering assist ECU 35 repeatedly executes the assist control program of FIG. 11 every predetermined short time. The assist control program of FIG. 11 is obtained by changing the processes of steps S11 and S14 of the assist control program of FIG. 2 according to the first embodiment to processes of steps S41 and S42. In step S41, a vehicle height selection signal is input from the vehicle height ECU 76 instead of the input of the fail flag FAL of the first embodiment. The point that the steering torque Tr, the steering angle θ, and the vehicle speed V are input is the same as in the case of the first embodiment.

  Then, the steering assist ECU 35 determines in step S42 whether the input vehicle height selection signal represents low or high. If the vehicle height selection signal indicates low, the steering assist ECU 35 determines “Yes” in step S42, and executes the processes of steps S15 and S17 similar to those in the above embodiment. As a result of the processing in steps S15 and S17, the control amount Tas−Tav (subtracting the first damping control amount Tav1 determined in accordance with the steering angular velocity θv from the assist torque Tas determined in accordance with the steering torque Tr and the vehicle speed V). Assist torque corresponding to = Tas−Tav1) is applied to the turning operation of the steering handle 11.

  If the vehicle height selection signal indicates high, the steering assist ECU 35 determines “No” in step S42, and executes the processes of steps S16 and S17 similar to those in the first embodiment. As a result of the processing in steps S16 and S17, the control amount Tas-Tav (subtracting the second damping control amount Tav2 determined according to the steering angular velocity θv from the assist torque Tas determined according to the steering torque Tr and the vehicle speed V ( Assist torque corresponding to = Tas−Tav2) is applied to the turning operation of the steering handle 11. However, the second damping control amount Tav2 is absolute to compensate for the increase in the damping coefficient with respect to the rotational motion around the kingpin axis of the left and right front wheels FW1 and FW2 due to the increase in the vehicle height as compared with the first damping control amount Tav1. It is a small value.

  In such a vehicle control apparatus according to the third embodiment, when the vehicle height is switched from low to high, the roll when the vehicle turns increases, the steering characteristics of the vehicle become understeer, and the left and right front wheels FW1, FW2 The damping coefficient for the rotational movement around the kingpin axis increases as shown by the change from the solid line to the broken line in FIG. On the other hand, as described above, the damping control amount Tav in the steering assist is changed from the first damping control amount Tav1 to the second damping control amount Tav2 in conjunction with the switching of the damping force (the solid line and the broken line in FIG. 5). See). That is, when the vehicle height becomes high, the attenuation control amount Tav in the steering assist is set to a value having a smaller absolute value than when the vehicle height is low.

  Therefore, even when the vehicle height is switched from low to high, the damping control amount Tav in the steering assist is shown by the increase in the attenuation coefficient with respect to the rotational motion around the kingpin axis of the left and right front wheels FW1, FW2 due to the change in the vehicle height. The value is changed from a large value to a small value as shown by the change from the solid line to the broken line in FIG. Then, as shown by a solid line in FIG. 12C, the overall friction coefficient including the steering system friction in the damping coefficient and damping control amount Tav becomes the same even if the vehicle height changes. As a result, it is possible to eliminate the influence on the steering feeling of the steering handle 11 due to the change in the attenuation coefficient accompanying the change in the vehicle height, and the driver can always steer the steering handle 11 with the same steering feeling.

  In the third embodiment, when the vehicle height is set to high, the attenuation control amount Tav may be controlled to be smaller in absolute value. In this case, the steering assist ECU 35 changes according to the steering angular velocity θv with reference to the third attenuation control amount table provided in the ROM, as shown in parentheses in step S16 of FIG. The third attenuation control amount Tav3 may be calculated and set as the attenuation control amount Tav. The third damping control amount Tav3 is set to a smaller value in absolute value than the second damping control amount Tav2 with respect to the same steering angular velocity θv (see FIG. 5).

  According to this modified example, the damping control amount in the steering assist is further smaller than that of the broken line as shown by the one-dot chain line in FIG. 12B, and the steering system friction is reduced to the damping coefficient and damping control amount Tav. As shown by the alternate long and short dash line in FIG. 12 (C), the overall friction coefficient including is smaller than in the case of the third embodiment. According to this, by switching the vehicle height to the high side, the driver can be made aware of the stability of the vehicle corresponding to the vehicle height state through the steering of the vehicle. That is, when the vehicle height is high, the vehicle is unstable, and the damping of the steering system is reduced. Therefore, the driver recognizes that the vehicle is unstable due to the high vehicle height by the steering operation of the steering wheel 11. it can.

  In the third embodiment, the vehicle height is switched between two levels of low and high, but may be switched to three or more levels. In this case, as the vehicle height is switched from the low side (low side) to the high side (high side), the damping control amount Tav in the steering assist may be set to a value with a small absolute value. Further, as indicated by a broken line in FIG. 10, a motion state quantity sensor 78 for detecting a motion state quantity of the vehicle, such as a vehicle speed, a yaw rate, a lateral acceleration, and a roll, is provided. The vehicle height may be switched and controlled in accordance with the amount of motion state of the vehicle. Also in this case, the vehicle height ECU 76 outputs a vehicle height selection signal indicating the vehicle height switching state to the steering assist ECU 35. Then, the steering assist ECU 35 may set the attenuation control amount Tav in the steering assist to a smaller absolute value as the vehicle height represented by the supplied vehicle height selection signal becomes higher.

c. Other Modifications Furthermore, the present invention is not limited to the first to third embodiments and the modifications, and various modifications can be adopted within the scope of the present invention.

  For example, in the first to third embodiments, the vehicle control device has been described in which the steering control device, the stabilizer control device, the damping force control device for the shock absorber 40, or the vehicle height control device are independently combined. However, in the vehicle control device including all of the steering control device, the stabilizer control device, the damping force control device, and the vehicle height control device, the damping control amount Tav in the steering assist control of the steering control device is represented by the stabilizer control device, the damping force control. The change control may be performed as in the first to third embodiments by a combination of the control states of the device and the vehicle height control device.

  Further, in the first to third embodiments, the steering operation of the steering handle 11 is assisted by driving the rack bar 14 with the electric motor 15. However, instead of this, the steering operation of the steering handle 11 may be assisted by driving the steering shaft 12 around the axis. In this case, as indicated by broken lines in FIGS. 1, 7, and 10, the electric motor 81 is assembled to the steering shaft 12, and the rotation of the electric motor 81 is transmitted to the steering shaft 12 via the speed reducer 82, so that the shaft 12 is transmitted. It may be driven around the axis. In this case, the speed reducer 82 may use a reduction gear mechanism including a combination of a small gear and a large gear, a planetary gear mechanism, and the like.

1 is an overall schematic diagram of a vehicle control device according to a first embodiment of the present invention. It is a flowchart of the assist control program performed by the electronic control unit for steering assistance of FIG. It is a flowchart of the stabilizer control program performed by the electronic control unit for stabilizers of FIG. 6 is a graph illustrating a relationship among steering torque, vehicle speed, and assist torque according to the first to third embodiments. 6 is a graph illustrating a relationship between a steering angular velocity and an attenuation control amount according to the first to third embodiments. (A) is a graph which shows the change characteristic of the damping coefficient with respect to the rotational motion of the left and right front wheels around the kingpin axis according to the first embodiment, and (B) is the change of the damping control amount in the steering assist control according to the first embodiment. It is a graph which shows a characteristic, (C) is a graph which shows the change characteristic of the comprehensive damping coefficient of a steering system concerning 1st Embodiment. It is a whole schematic diagram of the control device of the vehicles concerning a 2nd embodiment of the present invention. 8 is a flowchart of an assist control program executed by the steering assist electronic control unit of FIG. 7. (A) is a graph which shows the change characteristic of the damping coefficient with respect to the rotational motion around the kingpin axis of the left and right front wheels according to the second embodiment, and (B) is the change of the damping control amount in the steering assist control according to the second embodiment. It is a graph which shows a characteristic, (C) is a graph which shows the change characteristic of the comprehensive damping coefficient of a steering system concerning 2nd Embodiment. It is a whole schematic diagram of the control device of the vehicles concerning a 3rd embodiment of the present invention. It is a flowchart of the assist control program performed by the electronic control unit for steering assistance of FIG. (A) is a graph which shows the change characteristic of the damping coefficient with respect to the rotational motion around the kingpin axis of the left and right front wheels according to the third embodiment, and (B) is the change of the damping control amount in the steering assist control according to the third embodiment. It is a graph which shows a characteristic, (C) is a graph which shows the change characteristic of the comprehensive damping coefficient of a steering system concerning 3rd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Steering handle, 12 ... Steering shaft, 14 ... Rack bar, 15, 25 ... Electric motor, 21, 22 ... Stabilizer bar, 31 ... Steering torque sensor, 32 ... Steering angle sensor, 33 ... Vehicle speed sensor, 34 ... Rotation angle Sensors 35... Steering assist electronic control unit (steering assist ECU) 36. Stabilizer electronic control unit (stabilizer ECU) 40. Shock absorber 61. Changeover switch 62. ECU), 71 ... air chamber, 74 ... changeover switch, 75 ... vehicle height sensor, 76 ... vehicle height electronic control unit (vehicle height ECU).

Claims (5)

In a vehicle control device including a suspension control device and a steering control device,
In the steering control device,
An electric actuator that assists in turning the steered wheels according to the steering operation of the steering wheel;
Steering torque detection means for detecting steering torque applied to the steering wheel;
An assist torque determining means for determining an assist torque that changes according to the detected steering torque;
Steering angular velocity detection means for detecting the steering angular velocity of the steering handle;
An attenuation control amount determining means for determining an attenuation control amount that changes in accordance with the detected steering angular velocity and changes in accordance with a control state of the suspension control device;
A vehicle control apparatus comprising drive control means for driving and controlling the electric actuator in accordance with a control amount obtained by adding the determined attenuation control amount to the determined assist torque. The vehicle control device according to claim 1,
While providing an abnormality detection means for detecting an abnormality of the suspension control device in the suspension control device,
The damping control amount determining means sets the damping control amount to a different value depending on whether an abnormality of the suspension control device is detected by the abnormality detecting means or not. The vehicle control device according to claim 2,
The abnormality detection means detects an abnormality of the stabilizer control device for controlling the twisting force of the stabilizer bar provided in the suspension control device to suppress the roll of the vehicle,
The damping control amount determining means is configured to set the damping control amount around the kingpin axis of the steered wheels when the abnormality is detected by the abnormality detecting means, compared to when the abnormality is not detected. A control apparatus for a vehicle that sets a compensation control amount for compensating for a change in the damping coefficient with respect to the rotational motion of the vehicle or a value changed by a control amount larger than the compensation control amount. The vehicle control device according to claim 1,
The suspension control device includes damping force control means for changing and controlling the damping force by the shock absorber,
When the damping force of the shock absorber is high, the damping control amount determining means determines the damping control amount as a rotational motion around the kingpin axis of the steered wheel as the damping force increases, compared to when the damping force is low. A control apparatus for a vehicle, which is set to a value that is changed by a compensation control amount for compensating a change in an attenuation coefficient with respect to or a control amount that is larger than the compensation control amount. The vehicle control device according to claim 1,
The suspension control device includes vehicle height control means for changing and controlling the vehicle height,
When the vehicle height is high, the damping control amount determining means sets the damping control amount to a damping coefficient with respect to the rotational motion around the kingpin axis of the steered wheels as the vehicle height increases. A control apparatus for a vehicle, which is set to a value that is changed by a compensation control amount for compensating for a change in the amount or a control amount that is larger than the compensation control amount.

Images