JP2006103507A - Vehicular behavior control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicular behavior control device capable of improving roll feeling of a vehicle by improving the roll feeling in the early state of steering. <P>SOLUTION: The vehicular behavior control device 1 comprises an electric power steering device 10 turning right and left front wheels FW2, FW1 interlocking steering of a steering wheel 32, a steering angle sensor 61 detecting a steering angle of the steering wheel 32, a rate gyro detecting the roll angle speed of a vehicle, and an ECU 60 decreasing current value supplied to the electric motor 50 so as to decrease the assist amount of the electric power steering device 10, in case that the roll angle speed exceeds a predetermined threshold value when it is determined that steering of the steering wheel 32 is started. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a vehicle behavior control apparatus.

  Patent Document 1 below discloses a travel control device that reduces the roll of a vehicle without causing a passenger an uncomfortable feeling by causing a centrifugal force in the roll reduction direction to act on the vehicle without causing the vehicle to decelerate when the roll occurs in the vehicle. It is described in.

According to this travel control device, correction steering is performed in a direction in which centrifugal force in the roll reduction direction is applied to the vehicle in accordance with the degree of roll of the vehicle. As a result, the force that acts on the vehicle and generates the roll is reduced by the centrifugal force in the roll reduction direction by the correction steering, thereby reducing the roll of the vehicle without decelerating the vehicle.
JP 2000-219146 A

  On the other hand, the roll feeling felt by the driver of the vehicle does not deteriorate even if the roll occurs after the rear wheel grip feeling (hereinafter referred to as “rear grip feeling”) is obtained. If rolls occur before they are obtained (the initial stage of steering), the situation gets worse.

  According to the travel control device, excessive rolls that have already occurred can be reduced. However, in this travel control device, the roll feeling at the initial stage of steering cannot be reduced, so that the roll feeling cannot be improved.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a vehicle behavior control device capable of improving the roll feeling of the vehicle by improving the roll feeling at the initial stage of steering. And

  A vehicle behavior control device according to the present invention includes a steering device that steers a steered wheel in conjunction with steering of a steering wheel, a steering state detection unit that detects a steering state of the steering wheel, and a degree of roll of the vehicle. And a roll threshold detected by the roll status detector when the steering wheel steering is determined to be started based on the steering status detected by the steering status detector and the steering status detected by the steering status detector. Control means for controlling the steering device so as to reduce the steered amount of the steered wheels with respect to the steered amount of the steering wheel when larger than the value is provided.

  The roll before the rear grip feeling is obtained is caused by the lateral force of the front wheel, and the rear grip feeling is caused by the rear wheel lateral force that is generated behind the front wheel lateral force. According to the vehicle behavior control device of the present invention, since the steering device is controlled so as to reduce the steered amount of the steered wheels with respect to the steered amount of the steering wheel at the initial stage of steering, compared with the case where the steered amount is not decreased. Thus, the generation of front wheel lateral force is suppressed. As a result, the roll acceleration at the initial stage of steering is reduced by suppressing the lateral acceleration of the vehicle generated by the lateral force of the front wheels, so that the roll feeling can be improved.

  The vehicle behavior control device according to the present invention is a power steering device in which the steering device assists steering in accordance with the steering state of the steering wheel, and the control means reduces the assist amount so that the steering wheel It is preferable to reduce the turning amount of the steered wheels with respect to the steering amount.

  In this case, the assist amount of the power steering device is reduced at the initial stage of steering, and the generation of front wheel lateral force is suppressed. As a result, the lateral acceleration of the vehicle is suppressed, so that the roll of the vehicle at the initial stage of steering can be reduced.

  Moreover, it is preferable to use a roll angular velocity as a physical quantity indicating the degree of roll of the vehicle.

  Further, the vehicle behavior control apparatus according to the present invention provides a steered wheel with respect to the steering amount of the steering wheel when a predetermined time set according to a timing at which a lateral force is generated on the rear wheel of the vehicle has elapsed. It is preferable to end the control for reducing the amount of turning.

  In this way, by ending the control for reducing the steered amount in accordance with the timing at which the lateral force is generated at the rear wheel, it is possible to suppress only an increase in the front wheel lateral force before the rear wheel lateral force is generated. . Therefore, it is possible to suppress the roll in the initial stage of steering caused by the lateral force of the front wheels and maintain the lateral jerk (time change rate of the lateral acceleration) caused by the lateral force of the rear wheel, which is related to the size of the lateral jerk. It is possible to improve the roll feeling at the initial stage of steering while maintaining the feeling of rear grip.

  According to the present invention, it is possible to improve the roll feeling by including the control means for controlling the steering device so as to reduce the turning amount of the steered wheels with respect to the steering amount of the steering wheel in the initial stage of steering. Become.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the figure, the same reference numerals are used for the same or corresponding parts.

  First, the overall configuration of the vehicle behavior control apparatus 1 according to the present embodiment will be described with reference to FIG.

  An electric power steering device 10 that steers the left front wheel FW1 and the right front wheel FW2 in conjunction with the steering of the steering wheel 32 is used in a vehicle on which the behavior control device 1 is mounted. The left and right front wheels FW1 and FW2 are connected by a steering gear box 20 via a tie rod 12. The steering gear box 20 includes a rack 22 and a pinion 24 meshed with a gear cut in the rack 22. The rack 22 is provided to be slidable with respect to the steering gear box 20. A tie rod 12 is connected to both ends of the rack 22, and a steering wheel 32 is attached to the pinion 24 via a steering shaft 30.

  A reduction gear 40 is attached to an intermediate portion of the steering shaft 30, and an electric motor 50 is connected to the reduction gear 40. An electric control unit (hereinafter referred to as ECU) 60 is connected to the electric motor 50 so that a current controlled by the ECU 60 is supplied.

  Further, a steering angle sensor 61 composed of a rotary encoder or the like is provided at an intermediate portion of the steering shaft 30 and outputs a signal corresponding to the direction and magnitude of the steering angle θ input by the driver. A signal output from the steering angle sensor 61 is input to the ECU 60. This steering angle sensor functions as a steering state detection means.

  When a steering force is applied to the steering wheel 32, a steering torque is applied to the steering shaft 30. By rotating the pinion 24 by this steering torque, the rack 22 meshed with the pinion 24 is slid with respect to the steering gear box 20, and the left and right front wheels FW1, FW2 are steered via the tie rod 12. Further, when current is supplied to the electric motor 50, motor torque is applied to the steering shaft 30 via the speed reducer 40. That is, the steering shaft 30 is given both the steering torque by the steering force applied to the steering wheel 32 and the motor torque given by the electric motor 50.

  In addition to the steering angle sensor 61 described above, a vehicle speed sensor 62 that detects the speed of the vehicle, a lateral acceleration sensor 63 that detects the lateral acceleration of the vehicle, and a roll rate (roll angular speed) of the vehicle are detected at the input unit of the ECU 60. A rate gyro (roll state detecting means) 64 or the like is connected. On the other hand, a drive circuit or the like for driving the electric motor 50 is connected to the output portion of the ECU 60.

  The ECU 60 stores the contents stored therein by a microprocessor that performs calculations, a ROM that stores a program for causing the microprocessor to execute each process, a RAM that stores various data such as calculation results, and a 12V battery. A backup RAM or the like.

  When the ECU 60 drives the electric motor 50 to assist steering in accordance with the steering state of the steering wheel 32 and determines that a predetermined condition is satisfied based on the input from the various sensors, The electric motor 50 is driven so as to reduce the assist amount. That is, the ECU 60 functions as a control unit.

  Next, the operation of the behavior control apparatus 1 according to the present embodiment will be described with reference to FIG. FIG. 2 is a flowchart showing a roll control processing procedure in the behavior control apparatus 1. The roll control shown in FIG. 2 is started when the ignition switch of the vehicle is turned on and the ECU 60 is turned on, and is repeatedly executed at predetermined timings.

  In step S <b> 100, for example, a determination is made as to whether or not steering is started based on a change in the steering angle θ of the steering wheel 32 detected by the steering angle sensor 61. Here, if it is determined that the steering is started, the process proceeds to step S102. On the other hand, when the steering is not started, the process is temporarily exited.

  In step S102, the roll rate RR of the vehicle is read from the rate gyro 64. In the subsequent step S104, the lateral acceleration Gy of the vehicle is read from the lateral acceleration sensor 63.

  Next, in step S106, a roll rate threshold value RRtgt is calculated based on the lateral acceleration Gy of the vehicle read in step S104. Here, a map defining the relationship between the lateral acceleration Gy and the roll rate threshold value RRtgt is stored in the ROM of the ECU 60, and the roll rate threshold value RRtgt is obtained based on this map.

  Subsequently, in step S108, a determination is made as to whether roll rate RR is greater than roll rate threshold value RRtgt. If the roll rate RR is greater than the roll rate threshold value RRtgt, the process proceeds to step S110. On the other hand, when the roll rate RR is equal to or less than the roll rate threshold value RRtgt, the process is temporarily exited.

  In step S110, the current supplied to the electric motor 50 is reduced and the motor torque applied to the steering shaft 30 is reduced, so that the steering assist amount of the electric power steering device 10 is reduced.

  Subsequently, in step S112, a determination is made as to whether a predetermined time has elapsed after the start of steering. The predetermined time used for the determination is set in consideration of the timing at which a lateral force is generated on the rear wheel, that is, the timing at which the lateral jerk rises.

  Here, if a predetermined time has elapsed after the start of steering, the process proceeds to step S114. On the other hand, if the predetermined time has not elapsed since the start of steering, the assist amount decreasing process in step S110 is repeatedly executed until the predetermined time elapses.

  If a predetermined time has elapsed after the start of steering, in step S114, the assist amount reduction process is terminated, and the assist amount of the electric power steering apparatus 10 is returned to a normal value. Thereafter, the process is temporarily exited.

  According to the present embodiment, the assist amount of the electric power steering device 10 is reduced at the start of steering, and the lateral force generation timing of the front wheels FW1, FW2 is delayed. As a result, the rise of the lateral acceleration is delayed, so that the roll angle and roll rate of the vehicle at the initial stage of steering can be reduced. Further, when a predetermined time has elapsed after the start of steering, the assist amount reduction process is terminated, and the assist amount is returned to the normal value, so that the generation of the lateral force of the rear wheel is not hindered. Therefore, it is possible to suppress a roll in the initial stage of steering caused by the front wheel lateral force and to maintain a lateral jerk caused by the rear wheel lateral force. As a result, it is possible to improve the roll feeling while maintaining the rear grip feeling related to the size of the lateral jerk.

  Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications can be made. For example, in the present embodiment, the roll angular velocity indicating the degree of roll is used as a condition for determining whether or not to decrease the assist amount of the electric power steering apparatus 10, but the roll angle may be used instead. it can. The roll angle of the vehicle can be detected by a stroke sensor or the like.

  In the present embodiment, the lateral acceleration of the vehicle is directly measured by the lateral acceleration sensor 63, but it can also be obtained based on the steering angle detected by the steering angle sensor 61 and the vehicle speed detected by the vehicle speed sensor 62.

  Further, in the present embodiment, the generation timing of the front wheel lateral force is adjusted by reducing the assist amount of the electric power steering device 10, but the steering device has no steering gear ratio according to, for example, the vehicle speed and the steering angle. It is also possible to use a variable gear ratio steering that is changed in stages and adjust the generation timing of the front wheel lateral force by slowing the gear ratio.

  Furthermore, it is good also as a structure which adjusts the generation | occurrence | production timing of front-wheel lateral force by using a steer-by-wire type steering apparatus by which the steering wheel and the steered wheel were mechanically isolate | separated to the steering apparatus, and making a steering gain small.

  In this embodiment, the steering assist force is applied via the speed reducer 40 attached to the steering shaft 30. However, the speed reducer is mounted on the pinion shaft by arranging an electric motor in the rack and pinion type steering gear portion. It is also possible to apply a steering assist force to the pinion shaft via a pinion shaft assist type. Moreover, it is good also as a structure (rack axis assist type) which gives a steering assist force to a rack shaft directly with a reduction gear.

  Furthermore, a hydraulic power steering device can be applied instead of the electric power steering device 10.

It is a figure which shows the whole structure of the behavior control apparatus 1 which concerns on embodiment. It is a flowchart which shows the process sequence of the roll control in the behavior control apparatus 1 which concerns on embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Behavior control apparatus, 10 ... Electric power steering apparatus, 12 ... Tie rod, 20 ... Steering gear box, 22 ... Rack, 24 ... Pinion, 30 ... Steering shaft, 32 ... Steering wheel, 40 ... Reduction gear, 50 ... Electricity Motor 60 ... ECU 61 ... Steering angle sensor 62 ... Vehicle speed sensor 63 ... Lateral acceleration sensor 64 ... Rate gyro FW1 ... Front left wheel FW2 ... Front right wheel

Claims (4)

A steering device that steers the steered wheels in conjunction with steering of the steering wheel;
Steering state detection means for detecting the steering state of the steering wheel;
Roll state detection means for detecting the degree of rolling of the vehicle;
When it is determined that the steering of the steering wheel is started based on the steering state detected by the steering state detection unit, the degree of roll detected by the roll state detection unit is larger than a predetermined threshold value A vehicle behavior control device comprising: control means for controlling the steering device so as to reduce a turning amount of the steered wheel with respect to a steering amount of the steering wheel. The steering device is a power steering device that assists steering according to a steering state of the steering wheel,
2. The vehicle behavior control device according to claim 1, wherein the control unit reduces the turning amount of the steered wheels with respect to the steering amount of the steering wheel by reducing an assist amount. 3.   The vehicle behavior control device according to claim 1, wherein the roll degree of the vehicle is a roll angular velocity.   The control means performs control for reducing a turning amount of the steered wheel with respect to a steering amount of the steering wheel when a predetermined time set according to a timing at which a lateral force is generated on a rear wheel of the vehicle has elapsed. The vehicle behavior control device according to claim 1, wherein the vehicle behavior control device is terminated.

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