JP2012144117A - Vehicle behavior control system - Google Patents

Abstract

To improve the control performance of vehicle behavior stabilization control.
When a vehicle behavior stabilization control is performed by generating a target turning control amount according to a deviation between an actual turning state and a target turning state by a wheel braking force of a predetermined wheel to be controlled, two brake fluids are used. Among the hydraulic systems of pressure, the one to which the control target wheel belongs is set as a hydraulic control target and the master cut valve 41 of the hydraulic system is closed, and the other hydraulic system is set as a non-hydraulic control target. A vehicle behavior control device configured to open the master cut valve 42 of the hydraulic system and adjust the brake hydraulic pressure of the hydraulic system to be hydraulically controlled to generate the wheel braking force on the wheel to be controlled. When the actual turning behavior amount of the vehicle body exceeds a predetermined amount or the absolute value of the target turning control amount exceeds a predetermined amount, both hydraulic systems are set as hydraulic control targets, and the respective hydraulic systems are set. Stabilization control by the wheel braking force of each controlled wheel belonging to It is performed.
[Selection] Figure 1

Description

  The present invention relates to a vehicle behavior control device that controls the behavior of a vehicle during a steering operation to improve running stability.

  A yaw moment in the turning direction is generated in the vehicle body along with the steering operation. 2. Description of the Related Art Conventionally, there is known a vehicle behavior control device that increases traveling stability by applying a yaw moment in the reverse direction to a vehicle body to reduce the yaw moment when it is determined that the yaw moment is excessive. If the vehicle body shows an oversteer tendency, this vehicle behavior control device generates a yaw moment in the opposite direction to the tendency by a braking force applied to the front turning outer wheel. In addition, if the vehicle body shows an understeer tendency, the vehicle behavior control device generates a yaw moment in the opposite direction to the tendency by a braking force applied to the front turning inner wheel.

  This type of vehicle behavior control device is disclosed in the following Patent Documents 1-4. These vehicle behavior control devices of Patent Documents 1 to 4 control the behavior of a vehicle including a brake system actuator including a hydraulic system for the right front wheel and the left rear wheel and a hydraulic system for the left front wheel and the right rear wheel. Is. The vehicle behavior control device of Patent Document 1 sets one hydraulic system as a control target, sets the other hydraulic system as a non-control target, and sets the brake hydraulic pressure of the hydraulic system as the control target based on the vehicle state. By controlling, stabilization control of vehicle behavior is realized without using a master cylinder pressure sensor. Further, in the vehicle behavior control device of Patent Document 2, when a brake pedal is operated during brake hydraulic pressure control of one wheel cylinder in one hydraulic system, the other wheel cylinder in one hydraulic system is held. By controlling the duty of the valve according to the control state of the one wheel cylinder, an appropriate braking force is generated when the brake pedal is operated during the stabilization control of the vehicle behavior without using the master cylinder pressure sensor. In addition, the vehicle behavior control device of Patent Document 3 responds to a comparison result between a vehicle state and a control target of the wheel cylinder that is set based on the vehicle state with respect to the brake fluid pressure of one wheel cylinder in each hydraulic system. When the brake pedal is operated, the other wheel according to the comparison result between the vehicle state and the control reference of the other wheel cylinder set by correcting the control target according to the operation state of the brake pedal. By adjusting the brake fluid pressure of the cylinder, an appropriate braking force is generated when the brake pedal is operated during the stabilization control of the vehicle behavior without using the master cylinder pressure sensor. Further, the vehicle behavior control device of Patent Document 4 controls the brake hydraulic pressure of one wheel cylinder of one hydraulic system based on the vehicle state, and when the brake pedal is operated, By controlling the brake fluid pressure of the other wheel cylinder according to the control state, an appropriate braking force is generated when the brake pedal is operated during the stabilization control of the vehicle behavior without using the master cylinder pressure sensor.

JP 2005-035441 A JP 2005-035442 A JP 2005-035443 A JP 2005-035444 A

  Conventionally, in this type of vehicle behavior control device, vehicle behavior stabilization control is performed by generating a braking force on one of two wheels belonging to one hydraulic system. The reason why only one hydraulic system is to be controlled and the other hydraulic system is not to be controlled is that the driver brakes during stabilization control in a vehicle behavior control device that does not have a master cylinder pressure sensor. This is because when the operation is performed, the master cylinder pressure is supplied to the wheels belonging to the other hydraulic system. In the technique described in Patent Document 2-4, when the driver performs a brake operation during the stabilization control, the stabilization control among the two wheels belonging to the one hydraulic system is further performed. Therefore, the braking force is generated on the other wheel that does not generate the braking force.

  Here, the conventional vehicle behavior control device determines the maximum value of the turning control amount (that is, the yaw moment in the reverse direction) obtained by the braking force of one wheel belonging to one hydraulic system as the target turning control amount (in the reverse direction). When the target yaw moment does not exceed, the behavior of the vehicle can be stabilized by controlling the magnitude of the braking force. However, since the magnitude of the target turning control amount changes more or less depending on the vehicle state, when this target turning control amount exceeds the maximum value of the turning control amount that can be output by the braking force of one wheel. There is a possibility that the control performance for stabilizing the vehicle behavior will be reduced.

  Therefore, an object of the present invention is to provide a vehicle behavior control apparatus that can improve the disadvantages of the conventional example and improve the control performance of the vehicle behavior stabilization control.

  In order to achieve the above object, the present invention stabilizes vehicle behavior by generating a target turning control amount corresponding to a deviation between an actual turning state and a target turning state of a vehicle by a wheel braking force of a predetermined control target wheel. When performing control, one of the two hydraulic systems of the brake hydraulic pressure to which the wheel to be controlled belongs is set as a hydraulic control target, and the master cut valve of the hydraulic system is closed, and the other hydraulic system The pressure system is set as a non-hydraulic pressure control target, the master cut valve of the hydraulic pressure system is opened, and the brake fluid pressure of the hydraulic pressure control target hydraulic pressure system is adjusted to adjust the wheel to the control target wheel. A vehicle behavior control device for generating a braking force, wherein when the actual turning behavior amount of the vehicle body exceeds a predetermined amount or when the absolute value of the target turning control amount exceeds a predetermined amount, both the hydraulic systems are hydraulically controlled. Set as a target, husband belonging to each hydraulic system It is characterized by performing the stabilization control the wheel braking force of the controlled wheel of.

  Here, when the driver's brake operation is detected during the stabilization control in both the hydraulic systems, it is desirable to increase the brake hydraulic pressure of one of the hydraulic systems.

  The vehicle behavior control device according to the present invention is configured to control one of the two hydraulic systems when the actual turning behavior amount of the vehicle body is a predetermined amount or less or when the absolute value of the target turning control amount is a predetermined amount or less. Stabilization control is performed with the wheel braking force of the wheel, and when the actual turning behavior amount of the vehicle body exceeds a predetermined amount or the absolute value of the target turning control amount exceeds the predetermined amount, the control target wheels of both hydraulic systems are controlled. Stabilization control is performed by wheel braking force. In other words, this vehicle behavior control device uses the other hydraulic system to generate a target turning control amount that cannot be generated by one hydraulic system when the behavior of the vehicle in the turning direction becomes large. Thus, stabilization control of vehicle behavior is realized. Therefore, since this vehicle behavior control device can turn while keeping the behavior of the vehicle stable even under a situation where the vehicle behavior becomes large, the control performance of the stabilization control is improved.

FIG. 1 is a diagram illustrating an example of a vehicle to which a vehicle behavior control device according to the present invention is applied. FIG. 2 is a diagram showing a configuration of a braking system used by the vehicle behavior control device according to the present invention in the stabilization control of the vehicle behavior. FIG. 3 is a flowchart for explaining the operation of the vehicle behavior control apparatus according to the present invention.

  Embodiments of a vehicle behavior control apparatus according to the present invention will be described below in detail with reference to the drawings. The present invention is not limited to the embodiments.

[Example]
A vehicle behavior control apparatus according to a first embodiment of the present invention will be described with reference to FIGS.

  The vehicle behavior control device of this embodiment is prepared as a function of the electronic control unit (ECU) 1 shown in FIG.

  First, an example of a vehicle 10 to which this vehicle behavior control device is applied is shown in FIG.

The vehicle 10 is provided with a power source 20 such as an engine or a motor. The vehicle 10 travels by transmitting the power of the power source 20 to the driving wheels as a driving force. The vehicle 10 is provided with a braking system that stops or decelerates the traveling vehicle 10. The braking system is configured to generate a target wheel braking torque (target wheel braking force) with an individual magnitude for each of the wheels W _FL , W _FR , W _RL , W _RR . Here, friction force is generated between the engagement elements using the force of the brake fluid pressure, and thereby the target wheel braking torque (target wheel braking force) is applied to the wheels W _FL , W _FR , W _RL , W _RR. The thing is illustrated.

  First, as shown in FIGS. 1 and 2, this braking system includes a brake pedal 31 operated by a driver and an operation pressure (pedal depression force) accompanying the brake operation input to the brake pedal 31 with a predetermined boost ratio. And a brake booster (brake booster) 32 that doubles the brake pedal pressure multiplied by the brake booster 32 (hereinafter referred to as “master cylinder pressure”). .) And a reservoir tank 34 for storing brake fluid. The brake pedal 31, the brake booster 32, and the like function as a hydraulic pressure generator that generates a brake hydraulic pressure corresponding to the amount of operation of the brake pedal 31 by the driver.

The braking system includes a hydraulic pressure adjusting device (hereinafter referred to as “brake actuator”) 35 that can adjust the master cylinder pressure for each wheel W _FL , W _FR , W _RL , W _RR , and the brake actuator. The hydraulic fluid pipes 36 _FL , 36 _FR , 36 _{RL of the} wheels W _FL , W _FR , W _RL , W _RR to which the brake fluid pressure (master cylinder pressure or brake fluid pressure obtained by adjusting the master cylinder pressure) passed through 35 is transmitted. , 36 _RR and the brake fluid pressures of the hydraulic pipes 36 _FL , 36 _FR , 36 _RL , 36 _RR are supplied to the wheels W _FL , W _FR , W _RL , W _{RR respectively.} Braking device that generates braking force (consisting of a disc rotor or caliper, or a drum or wheel cylinder) 37 _FL , 37 _FR , 37 _RL , and 37 _RR .

The brake actuator 35 of the present embodiment includes a first hydraulic system that transmits brake hydraulic pressure to the right front wheel _WFR and the left rear wheel _WRL , and brake hydraulic pressure to the left front wheel _WFL and the right rear wheel _WRR . And a second hydraulic system that conveys the above. That is, the brake actuator 35 has a so-called X-pipe brake hydraulic pressure circuit. The first hydraulic system is supplied with brake hydraulic pressure from one hydraulic chamber inside the master cylinder 33 via the first hydraulic pipe 38. On the other hand, the brake hydraulic pressure is supplied to the second hydraulic system from the other hydraulic chamber inside the master cylinder 33 via the second hydraulic pipe 39.

  The brake actuator 35 includes master cut valves 41 and 42 as respective brake fluid flow control devices in the first and second hydraulic systems. A first hydraulic pipe 38 is connected to the master cut valve 41, and a second hydraulic pipe 39 is connected to the master cut valve 42. Each of these master cut valves 41 and 42 is a so-called normally-open flow rate adjusting electromagnetic valve that is normally in an open state, and executes control of the valve opening in accordance with energization by a command from the electronic control unit 1. . Therefore, each master cut valve 41, 42 controls the valve opening according to the energization amount, thereby adjusting the pressure of the brake fluid discharged from the pressurizing pumps 69, 70, which will be described later, on the master cylinder 33 side. Can be released.

In the brake actuator 35, the first hydraulic pipe 38 is connected to the connecting passage 43 through the master cut valve 41, and the second hydraulic pipe 39 is connected to the connecting passage 44 through the master cut valve 42. The Then, two branch passages 45 and 46 are connected to the connection passage 43 of the first hydraulic system as if branched from there, and the connection passage 44 of the second hydraulic system is branched therefrom. Two branch passages 47 and 48 are connected. In the first hydraulic circuit, connected to the liquid pressure line _{36 RL} of the right front wheel, each of the branch passages 45 and 46 respectively _{W FR} of the liquid pressure pipe _{36 FR} and the left rear wheel _{W RL.} On the other hand, in the second hydraulic system, it is connected to the liquid pressure line _{36 FL} of the liquid pressure pipe _{36 RR} and the left front wheel _{W FL} of the right rear wheel _{W RR} the branch passage 47, 48 of each, respectively.

Further, the on the branch passages 45, 46, 47 and 48, respectively of the brake _{37 FR, 37 RL, 37 RR} , 37 adjustable hydraulic pressure regulating pressure part of the brake fluid pressure for each _FL wheels _{W FR , W} RL, _W RR, are disposed for each _{W FL.} Its respective hydraulic pressure regulating pressure part, the wheels _{W FR, W RL, W RR} , retention valves provided for each _{W FL} 50, 51, 52, 53 and the liquid pressure discharge passages 54, 55, 56, and 57 under reduced pressure It consists of valves 58, 59, 60, 61. Here, holding valves 50, 51, 52, 53 are respectively provided on the respective branch passages 45, 46, 47, 48, and further liquids are provided downstream of these holding valves 50, 51, 52, 53. The pressure discharge passages 54, 55, 56, and 57 are connected so as to be branched from the branch passages 45, 46, 47, and 48, respectively. And, on each of the hydraulic pressure discharge passages 54, 55, 56, 57, pressure reducing valves 58, 59, 60, 61 are respectively provided. The term “downstream” as used herein refers to the downstream side in the flow direction of the brake fluid when the brake pedal is operated (that is, the direction toward the braking devices 37 _FL , 37 _FR , 37 _RL , 37 _RR ).

  The holding valves 50, 51, 52, 53 are so-called normally open solenoid valves, which are normally opened in a non-excited state and are in an excited state in response to energization according to a command from the electronic control device 1. It is something to be made. On the other hand, the pressure reducing valves 58, 59, 60, 61 are so-called normally closed solenoid valves, which are normally closed in a non-excited state and are in an excited state in response to energization according to a command from the electronic control unit 1. It is something that can be said.

  The brake actuator 35 includes a hydraulic discharge collecting passage 62 that brings together the respective hydraulic discharge passages 54 and 55 of the first hydraulic system, and respective hydraulic discharge passages 56 and 55 of the second hydraulic system. The hydraulic discharge collecting passages 63 are provided together, and the hydraulic discharge collecting passages 62 and 63 are connected to the auxiliary reservoirs 64 and 65, respectively.

  Further, in the first hydraulic system, a pump passage 66 that branches from a branch point between the connection passage 43 and the branch passages 45 and 46 and is connected to the hydraulic discharge collecting passage 62 is provided. Similarly, the second hydraulic system is provided with a pump passage 67 that branches from a branch point between the connecting passage 44 and each of the branch passages 47 and 48 and is connected to the hydraulic discharge collecting passage 63.

The pump passages 66 and 67 are respectively provided with pressurizing pumps (pressurizing sections) 69 and 70 driven by an electric motor (here, one electric motor 68). Each of these pressurizing pumps 69 and 70 discharges the brake fluid toward each branch point on the master cut valve 41 and 42 side, respectively, and the branch passages 45 and 46 and the branch passages 47 and 48 respectively. To supply the brake fluid pressure. That is, the first hydraulic pressure system pressurizing pump 69 increases the brake hydraulic pressure supplied to the respective braking devices 37 _FR and 37 _RL in order to increase the braking force generated on the right front wheel W _FR and the left rear wheel W _RL . Increase pressure. On the other hand, the pressurizing pump 70 of the second hydraulic pressure system _controls the brake hydraulic pressure supplied to the respective braking devices 37 _FL and 37 _RR in order to increase the braking force generated on the left front wheel W _FL and the right rear wheel W _RR . Increase pressure. The electric motor 68 is driven by power supply from a battery (not shown). In addition, damper chambers 71 and 72 for avoiding pulsation of the brake fluid discharged from the pressurizing pumps 69 and 70 are disposed in the pump passages 66 and 67, respectively.

  The brake actuator 35 is provided with suction passages 73 and 74 that are branched from the first and second hydraulic pipes 38 and 39 and connected to the auxiliary reservoirs 64 and 65, respectively. Reservoir cut check valves 75 and 76 are disposed on the auxiliary reservoirs 64 and 65 side of the respective suction passages 73 and 74.

  This braking system has a pressure increasing mode for increasing the braking force of the wheel to be controlled, a holding mode for maintaining the braking force of the wheel to be controlled as it is, and a pressure reducing mode for decreasing the braking force of the wheel to be controlled. is there. When controlling the wheel to be controlled in the pressure increasing mode, the holding mode or the pressure reducing mode, the electronic control unit 1 closes the master cut valves 41 and 42 of the hydraulic system including the wheel to be controlled.

When the control target wheel is included in the first hydraulic system, the master cut valve 41 is closed, and the first hydraulic pipe 38 and the connection passage 43 upstream of the holding valves 50 and 51 are shut off. For example, when the right front wheel _WFR is a wheel to be controlled, the electronic control unit 1 performs control so that the holding valve 50 is opened and the pressure reducing valve 58 is closed when controlling to the pressure increasing mode. Thus, the brake fluid pressure to the braking device 37 _FR of the right front wheel W _FR is increased. The electronic control unit 1, when controlling to hold mode, the hold valve 50 to pressure reducing valve 58 is controlled to be closed, the brake fluid pressure to the braking device 37 _FR of the right front wheel W _FR Is kept in the size at that time. Further, when the electronic control unit 1 controls to the decompression mode, the braking device 37 _FR of the right front wheel W _FR is controlled by controlling the holding valve 50 to be closed and the decompression valve 58 to be opened. Reduce brake fluid pressure to Also for the left rear wheel _WRL , the holding valve 51 and the pressure reducing valve 59 are controlled in the same manner as in the case of the right front wheel _WFR according to the mode.

Similarly, when the control target wheel is included in the second hydraulic system, the master cut valve 42 is closed and the second hydraulic pipe 39 and the connection passage 44 upstream of the holding valves 52 and 53 are connected. Shut off. For example, when the left front wheel _WFL is a wheel to be controlled, the electronic control unit 1 performs control so that the holding valve 53 is opened and the pressure reducing valve 61 is closed when controlling to the pressure increasing mode. Thus, the brake fluid pressure to the braking device 37 _FL of the left front wheel W _FL is increased. Further, the electronic control unit 1 controls the holding valve 53 and the pressure reducing valve 61 to be closed when controlling to the holding mode, whereby the brake hydraulic pressure to the braking device 37 _FL of the left front wheel W _FL is controlled. Is kept in the size at that time. Further, when the electronic control unit 1 controls to the decompression mode, the electronic control unit 1 controls the holding valve 53 to be in a closed state and the decompression valve 61 to be in an open state, whereby the braking device 37 _FL of the left front wheel W _FL is controlled. Reduce brake fluid pressure to Also for the right rear wheel _WRR , the holding valve 52 and the pressure reducing valve 60 are controlled in the same manner as in the case of the left front wheel _WFL depending on the mode.

The vehicle behavior control device performs stabilization control of vehicle behavior during turning. The stabilization control is so-called vehicle stability control. The vehicle 10 may show a neutral steering tendency or an oversteering tendency or an understeering tendency during the turning motion accompanying the steering operation of the steering wheel 81 by the driver. The electronic control unit 1 determines the behavior of the vehicle 10, that is, the actual turning state (actual turning state) of the vehicle body based on the vehicle travel information such as the vehicle speed, the vehicle longitudinal acceleration, the vehicle lateral acceleration, and the yaw rate. At the time of the determination, the yaw moment of the vehicle body indicating the actual turning state is calculated based on the vehicle travel information. The vehicle speed is estimated from, for example, the wheel speeds of the wheels W _FL , W _FR , W _RL , W _RR (detected by the wheel speed sensors 91, 92, 93, 94), the rotational speed of the output shaft of the transmission (not shown), and the like. That's fine. The vehicle longitudinal acceleration may be detected by the vehicle longitudinal acceleration sensor 95, and the vehicle lateral acceleration may be detected by the vehicle lateral acceleration sensor 96. Further, the yaw rate may be detected by the yaw rate sensor 97.

  When the actual turning state of the vehicle body shows an oversteer tendency, the wheel braking force is generated on one of the front and rear or both turning outer wheels to reverse the yaw moment (actual turning behavior amount) indicating the oversteer tendency. A yaw moment (a turning control amount) can be applied to the vehicle body. Therefore, when the vehicle body shows an oversteer tendency, the oversteer tendency can be suppressed by the wheel braking force generated in the turning outer wheel. For this reason, the vehicle 10 generates an appropriate amount of turning control amount by the wheel braking force of the turning outer wheel, thereby suppressing the actual turning state that is excessively oversteered to the target turning state and reducing the target turning state. The swivel operation can be performed while keeping.

  In addition, when the actual turning state of the vehicle body shows an understeer tendency, the wheel braking force is generated on one or both of the front and rear turning inner wheels to reverse the yaw moment (actual turning behavior amount) indicating the understeer tendency. A yaw moment (a turning control amount) can be applied to the vehicle body. For this reason, when the vehicle body shows an understeer tendency, the understeer tendency can be suppressed by the wheel braking force generated on the turning inner wheel. For this reason, the vehicle 10 generates an appropriate amount of turning control amount by the wheel braking force of the turning inner wheel, thereby suppressing the actual turning state in which the excessive understeer tendency tends to be the target turning state and maintaining the target turning state. The swivel operation can be performed while standing.

  The target turning state is a state of turning with a target turning behavior amount (a yaw moment having a target magnitude), for example, a state showing a neutral steer tendency or a weak understeer tendency. The electronic control unit 1 calculates a reverse target yaw moment (target turning control amount) generated for realizing the target turning state regardless of the tendency of the actual turning state of the vehicle body. The target yaw moment in the opposite direction is determined according to the deviation between the actual turning state and the target turning state, in other words, the difference between the actual turning behavior amount and the target turning behavior amount.

  Here, in this braking system, a master cylinder pressure sensor for detecting the master cylinder pressure is not prepared. For this reason, the vehicle behavior control device cannot grasp the driver's brake operation from the change in the master cylinder pressure. Therefore, this vehicle behavior control device takes into account the case where the driver performs a brake operation during the vehicle behavior stabilization control, and when performing the stabilization control, the first hydraulic system or the second hydraulic pressure. Only one of the systems is set as a hydraulic control target, and the other hydraulic system is set as a non-hydraulic control target so that hydraulic control is not performed. Therefore, the electronic control unit 1 performs the stabilization control by the wheel braking force of the control target wheel belonging to the hydraulic system that is the hydraulic pressure control target. When performing the stabilization control, the master cut valve 41 (42) of the hydraulic system to be hydraulically controlled is closed, and the master cut valve 42 (41 of the hydraulic system to be non-hydraulic controlled) is used. ) Is left open. As a result, when the driver performs a brake operation during the stabilization control, the master cylinder pressure corresponding to the brake operation is supplied to the wheel of the hydraulic system that is the target of non-hydraulic control. The braking force accompanying the brake operation can be applied to the vehicle body by the wheel braking force.

  By the way, as the actual turning behavior amount increases, the oversteer tendency or the understeer tendency becomes stronger. Therefore, in order to realize the target turning state, it is necessary to increase the target turning control amount as the actual turning behavior amount increases. In order to increase the target turning control amount, it is necessary to increase the wheel braking force of the wheel to be controlled as the target turning control amount increases. However, on the braking system, the wheel braking force has an upper limit that can be generated. For this reason, if the wheels to be controlled are limited to those belonging to one hydraulic system, if the actual turning behavior amount (in other words, the target turning control amount) exceeds a predetermined amount, The target turning control amount cannot be generated only by the wheel braking force of the wheel to be controlled in the hydraulic system, and the control performance of the stabilization control to the target turning state may be lowered.

  Here, looking at the other hydraulic system that is subject to non-hydraulic control, this hydraulic system includes wheels that can be controlled wheels for stabilization control together with the controlled wheels of one hydraulic system. Belongs to. For example, when an oversteer tendency is indicated, if the outer turning wheel on the front side of one hydraulic system is set as the control target wheel, the outer turning wheel on the rear side of the other hydraulic system can also be set as the control target wheel. Further, when an understeer tendency is exhibited, if the turning inner wheel on the rear side of one hydraulic system is set as the control target wheel, the turning inner wheel on the front side of the other hydraulic system can also be set as the control target wheel.

  Therefore, when the actual turning behavior amount is equal to or smaller than the predetermined amount or the absolute value of the target turning control amount is equal to or smaller than the predetermined amount, the vehicle behavior control device sets one hydraulic system as a hydraulic control target and Stabilization control of the vehicle behavior is performed by setting the hydraulic system as a non-hydraulic control target and generating wheel braking force on the control target wheel of one of the hydraulic systems. On the other hand, when the actual turning behavior amount exceeds a predetermined amount or when the absolute value of the target turning control amount exceeds a predetermined amount, this vehicle behavior control device makes both hydraulic systems subject to hydraulic pressure control, respectively. The vehicle behavior stabilization control is performed by generating wheel braking force on the control target wheel of the hydraulic system.

  The predetermined amount is determined by, for example, an upper limit value of the wheel braking force that can be generated in one wheel or a correction value that takes into account the error due to the viscosity of the oil passage or brake fluid with respect to the upper limit value. Specifically, the wheel braking force of the upper limit value or the correction value is generated by one wheel to be controlled, and is determined by the turning control amount (moment in the reverse direction) generated in the vehicle body at that time. For example, a clockwise moment is positive. In this case, the predetermined amount for the actual turning behavior amount is a value obtained by subtracting the turning control amount (moment in the reverse direction) generated by the wheel braking force of the upper limit value or the correction value from the target turning behavior amount. The predetermined amount for the target turning control amount is an absolute value of the turning control amount (moment in the reverse direction) generated by the wheel braking force of the upper limit value or the correction value.

Here, when both hydraulic systems are controlled by hydraulic pressure, both master cut valves 41 and 42 are closed. Therefore, even if the driver performs a brake operation, the master cylinder pressure does not change. It is not transmitted to the wheels W _FL , W _FR , W _RL , and W _RR . For this reason, when the driver performs a brake operation during the stabilization control in this case, the hydraulic control amount of one of the two hydraulic systems to be hydraulic controlled is set to the current target hydraulic control. Increase more than the amount.

  This will be specifically described below with reference to the flowchart of FIG.

  First, the electronic control unit 1 determines whether the vehicle body is in an understeer (US) state or an oversteer (OS) state that requires execution of vehicle behavior stabilization control based on vehicle travel information such as the yaw rate. Determine (step ST1). The determination in step ST1 may be performed constantly, but may be performed in response to detection of the driver's steering operation based on a detection signal from the steering angle sensor 82 (steering angle of the steering wheel 81), for example. .

  If the actual turning state of the vehicle body does not indicate an excessive understeer tendency or an excessive oversteer tendency, for example, if the electronic control apparatus 1 is in a target turning state, the electronic control device 1 makes a negative determination in step ST1. In this case, the determination in step ST1 is repeated.

  On the other hand, if the actual turning state of the vehicle body shows an excessive understeer tendency or an excessive oversteer tendency, the electronic control unit 1 makes an affirmative determination in step ST1. In this case, the electronic control unit 1 determines whether or not the understeer state or the oversteer state exceeds a feasible limit of the stabilization control in one hydraulic system (step ST2). Here, it is determined whether the actual turning behavior amount exceeds the predetermined amount or whether the absolute value of the target turning control amount exceeds the predetermined amount. As the actual turning behavior amount, the yaw moment obtained at the time of determination in step ST1 may be used. Further, the target turning control amount is obtained from the difference between the actual turning behavior amount and the target turning behavior amount.

  In step ST2, a negative determination is made when the actual turning behavior amount is equal to or smaller than a predetermined amount or when the absolute value of the target turning control amount is equal to or smaller than the predetermined amount. In this case, the target turning control amount is generated only by the wheel braking force of the wheel to be controlled belonging to one hydraulic system (one of the first hydraulic system or the second hydraulic system). Therefore, the vehicle body can be brought into the target turning state with the wheel braking force. For this reason, the electronic control unit 1 sets one hydraulic system as a hydraulic control target, and sets the other hydraulic system as a non-hydraulic control target, and controls one hydraulic system as the hydraulic control target. Stabilization control is executed by the wheel braking force of the target wheel (step ST3).

For example, in this case, if an understeering tendency is shown during a right turn, the second hydraulic system to which the right rear wheel _WRR , which is a wheel to be controlled, belongs is set as a hydraulic control target, and an understeering tendency is shown during a left turn. If so, the first hydraulic system to which the left rear wheel _WRL , which is the control target wheel, belongs is set as the hydraulic control target. Also, in this case, if an oversteer tendency is shown during a right turn, the second hydraulic system to which the front left wheel _WFL , which is the control target wheel, belongs is set as a hydraulic control target, and an oversteer tendency is shown during a left turn. if indicated, the first hydraulic system Field of the right front wheel W _FR is controlled wheel liquid pressure control target.

  The electronic control unit 1 obtains the target turning control amount based on the actual turning behavior amount and the target turning behavior amount at that time, and the target wheel braking force of the control target wheel that can generate the target turning control amount in the vehicle body. Ask for. Then, the electronic control unit 1 controls the brake actuator 35 so that the target wheel braking force is generated in the wheel to be controlled. In that case, among the wheels of the hydraulic system to be hydraulically controlled, the wheels to be controlled are controlled to the pressure increasing mode, and the remaining wheels are controlled to the holding mode. Thereby, the vehicle 10 can suppress the understeer tendency or the oversteer tendency and can turn in the target turning state.

  Here, when the driver performs a brake operation during the stabilization control, in the vehicle 10, the master cut valve 41 (42) of the hydraulic system that is the target of non-hydraulic control is opened. Therefore, the master cylinder pressure is supplied to each wheel belonging to this hydraulic system, and a wheel braking force corresponding to the brake operation is generated on this wheel. Therefore, the vehicle behavior control device can generate a braking force corresponding to the braking operation during the stabilization while stabilizing the vehicle behavior.

  When the driver stops the brake operation, the supply of the master cylinder pressure to the wheels of the hydraulic system subject to non-hydraulic control ends. After executing the stabilization control in step ST3, the electronic control unit 1 returns to step ST1 and repeats the arithmetic processing. Therefore, if it is determined that the stabilization control is necessary even after the brake operation is stopped, Stabilization control in one hydraulic system being executed or stabilization control in both of the following hydraulic systems is executed.

  In step ST2, an affirmative determination is made when the actual turning behavior amount exceeds a predetermined amount or when the absolute value of the target turning control amount exceeds a predetermined amount. In this case, only the wheel braking force of the wheel to be controlled belonging to one hydraulic system (either the first hydraulic system or the second hydraulic system) is applied to the vehicle body by the wheel braking force. The generated turning control amount is insufficient with respect to the target turning control amount, and the vehicle body cannot be brought into the target turning state. For this reason, the electronic control unit 1 sets both the first hydraulic system and the second hydraulic system as hydraulic control targets, and controls the wheel control target wheels belonging to the first and second hydraulic systems, respectively. Stabilization control is executed by power (step ST4).

For example, in this case, if shows the understeer tendency during the right turn, the belongs is likewise controlled wheel and the first hydraulic system Field of the right front wheel W _FR is controlled wheel right rear wheel W _RR If the two-hydraulic pressure system is subject to hydraulic control and shows an understeer tendency when turning left, the left front wheel W, which is the control target wheel, is the same as the first hydraulic system to which the left rear wheel _WRL , which is the control target wheel, belongs. The second hydraulic system to which the _FL belongs is set as a hydraulic control target. Further, in this case, if an oversteer tendency is shown when turning right, the left front wheel _WFL , which is the control target wheel, belongs to the first hydraulic system to which the left rear wheel _WRL , which is the control target wheel, belongs. a second hydraulic system in the hydraulic control object, if shows the oversteer tendency during turning left, right rear is likewise controlled wheel and the first hydraulic system Field of the right front wheel W _FR is controlled wheel The second hydraulic system to which the wheel _WRR belongs is set as a hydraulic control target.

  Also in this case, the electronic control unit 1 obtains the target turning control amount based on the actual turning behavior amount and the target turning behavior amount at that time. The electronic control unit 1 obtains the target wheel braking force of each control target wheel that can generate the target turning control amount on the vehicle body, and generates the target wheel braking force on each control target wheel. The brake actuator 35 is controlled. At that time, the target wheel braking force of each wheel to be controlled may be set to an equal magnitude for each wheel to be controlled, and the magnitude may be changed before and after. For example, in the latter case, the wheel braking force of the wheel to be controlled when the stabilization control is performed in one hydraulic system is generated up to the above-described upper limit value or correction value, and the wheel control for the shortage relative to the target turning control amount is generated. Power is generated in the control target wheel belonging to the other hydraulic system. In that case, among the wheels of each hydraulic system, the wheel to be controlled is controlled to the pressure increasing mode, and the remaining wheels are controlled to the holding mode. Thus, the vehicle 10 can turn in the target turning state by performing the stabilization control in both hydraulic systems, thereby suppressing the understeer tendency or the oversteer tendency.

  Here, when the driver performs a brake operation during the stabilization control, the master cut valves 41 and 42 of both hydraulic systems are closed in the vehicle 10, so that the master accompanying the brake operation Cylinder pressure cannot be supplied to any wheel. For this reason, in this case, the electronic control unit 1 first determines whether or not the driver has performed a brake operation by checking whether or not the stop switch 98 is outputting an ON signal (step ST5). . The stop switch 98 is a switch for lighting a stop lamp (not shown) at the rear end of the vehicle, and outputs an ON signal in conjunction with the driver's brake operation.

  If the ON signal of the stop switch 98 is not detected and it is determined that the stabilization control is necessary thereafter, the electronic control device 1 can be directly used in accordance with the actual turning behavior amount or the target turning control amount. The stabilization control by the hydraulic system is continued or switched to the stabilization control by one hydraulic system.

  On the other hand, when the electronic control unit 1 detects the ON signal of the stop switch 98, the electronic control unit 1 determines that the driver has performed a brake operation, and controls one hydraulic pressure control amount (brake in both hydraulic systems). (Hydraulic pressure) is increased (step ST6). As a result, the wheel braking force of the wheel belonging to the hydraulic system to be increased is increased as compared with the stabilization control being executed, so that the vehicle behavior control device is stabilizing the vehicle behavior while A braking force can be generated in accordance with the braking operation.

  Here, the hydraulic system to be increased may be set to any of the two hydraulic systems. For example, the hydraulic pressure system to which the wheel to be controlled that generates the insufficient wheel braking force described above belongs is the target of the increase in the brake hydraulic pressure. As a result, the brake fluid pressure can be increased more than when the reverse hydraulic system is the target of the brake fluid pressure increase.

  In step ST6, in the hydraulic system to be increased, the hydraulic pressure control amount (brake hydraulic pressure) is increased more than the target hydraulic pressure control amount (target brake hydraulic pressure) for stabilizing control of the wheel to be controlled. . In addition, the wheel to increase the brake fluid pressure may be only the wheel to be controlled, but considering the stability of the vehicle behavior, the wheel including the wheel that is in the holding mode at the time of stabilization control is also subject to increase. It is preferable to do. For this reason, in step ST6, the wheel is controlled from the holding mode to the pressure increasing mode. In step ST6, since the pedal depression force by the driver's brake operation is not known, the brake fluid pressure may be increased so as to increase the wheel braking force to the above upper limit value or the correction value.

  The electronic control unit 1 determines whether or not the on signal from the stop switch 98 is no longer detected, that is, whether or not the stop switch 98 is turned off (step ST7).

  Here, when the ON signal is continuously detected, the electronic control unit 1 continues to increase the brake fluid pressure being executed.

  On the other hand, when the ON signal is no longer detected, the electronic control unit 1 decreases the brake fluid pressure increased in step ST6 by the increment (step ST8), and returns to step ST1. In that case, the wheel unrelated to the stabilization control switched to the pressure increasing mode is switched in the order of the pressure reducing mode and the holding mode. As a result, when it is determined that the stabilization control is necessary thereafter, the electronic control unit 1 directly performs the stabilization control by the two hydraulic systems according to the actual turning behavior amount or the target turning control amount. Or switch to stabilization control by one hydraulic system.

  As described above, this vehicle behavior control device can be used for various understeering trends of various magnitudes when the vehicle behavior shows an understeering tendency or an oversteering tendency even if the braking system does not include a master cylinder pressure sensor. A target turning control amount (a yaw moment in the reverse direction) suitable for the oversteer tendency can be applied to the vehicle body, and stabilization control to the target turning state can be realized. Further, this vehicle behavior control device supplies the master cylinder pressure with the other hydraulic system if the stabilization control being performed is performed with one hydraulic system when the driver performs a brake operation. Thus, a braking force corresponding to the brake operation can be generated in the vehicle body. Furthermore, this vehicle behavior control device increases the brake hydraulic pressure of one of the hydraulic systems when the stabilization control during the brake operation is performed in both hydraulic systems, thereby The braking force accompanying the operation can be generated in the vehicle body.

  By the way, in this example, after returning to step ST1 after the brake operation is finished, for example, the hydraulic system to which the wheel to be controlled that generates the insufficient wheel braking force belongs is set as the brake hydraulic pressure in step ST6. If the target is to be increased, it may be returned to step ST1 while the brake is being operated. In step ST6, it is preferable to set the brake fluid pressure to the average value or the upper limit value of the master cylinder pressure based on the master cylinder pressure generated with the driver's braking operation. Thereby, when stabilization control with only one hydraulic system is selected in the subsequent step ST3, it is possible to suppress a change in the wheel braking force accompanying the brake operation. That is, in this case, the hydraulic system that is the target of the increase in brake hydraulic pressure is switched to the non-hydraulic control target, and the master cut valve 41 (42) of this hydraulic system is opened. The master cylinder pressure corresponding to the brake operation is supplied to the wheels of the system. Here, if the brake fluid pressure in step ST6 is set to the average value or the upper limit value of the master cylinder pressure, fluctuations in the brake fluid pressure when the master cut valve 41 (42) is opened can be suppressed. The change of the wheel braking force accompanying the brake operation can be suppressed. The average value of the master cylinder pressure can be obtained as a learning value based on the estimated value of the master cylinder pressure estimated from the wheel speed change or the like during the previous braking operation. Further, the upper limit value of the master cylinder pressure can be grasped in advance from the specifications of the braking system.

  In this embodiment, a braking system not provided with a master cylinder pressure sensor is taken as an example. However, this vehicle behavior control device also makes the above-described control target for the vehicle 10 in which the master cylinder pressure sensor is disposed in either one of the first or second hydraulic pipes 38 and 39. Good. Thereby, for example, even when the detection accuracy of the master cylinder pressure sensor is lowered due to secular change or the like, the vehicle behavior control device can obtain the same effect as described above regardless of the detection result.

  As described above, the vehicle behavior control device according to the present invention is useful for a technique for improving the control performance of the vehicle behavior stabilization control.

1 Electronic Control Device 10 Vehicle 31 Brake Pedal 33 Master Cylinder 35 Brake Actuator 37 _FL , 37 _FR , 37 _RL , 37 _RR Braking Device 41, 42 Master Cut Valve 50, 51, 52, 53 Holding Valve 58, 59, 60, 61 Pressure reducing valve 81 Steering wheel 82 Steering angle sensor 91, 92, 93, 94 Wheel speed sensor 95 Vehicle longitudinal acceleration sensor 96 Vehicle lateral acceleration sensor 97 Yaw rate sensor 98 Stop switch W _FL , W _FR , W _RL , W _RR wheel

Claims (2)

When performing stabilization control of vehicle behavior by generating a target turning control amount corresponding to the deviation between the actual turning state and the target turning state of the vehicle by the wheel braking force of a predetermined wheel to be controlled, the two brake hydraulic pressures Among the hydraulic systems, the one to which the control target wheel belongs is set as a hydraulic control target, the master cut valve of the hydraulic system is closed, and the other hydraulic system is set as a non-hydraulic control target. A vehicle behavior control device that opens the master cut valve of the hydraulic system and adjusts the brake hydraulic pressure of the hydraulic system to be hydraulically controlled to generate the wheel braking force on the wheel to be controlled. And
When the actual turning behavior amount of the vehicle body exceeds a predetermined amount, or when the absolute value of the target turning control amount exceeds a predetermined amount, both the hydraulic systems are set as hydraulic pressure control targets and belong to the respective hydraulic systems. A vehicle behavior control device characterized in that the stabilization control is performed by a wheel braking force of each wheel to be controlled.   2. The brake fluid pressure of one of the hydraulic systems is increased when a driver's brake operation is detected during the stabilization control in both the hydraulic systems. Vehicle behavior control device.

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