JP5353668B2 - Vehicle motion control device - Google Patents

Description

  The present invention relates to a vehicle motion control device that applies braking force to drive wheels of a vehicle to suppress idling of the drive wheels.

  Until now, in a vehicle that is turning, an engine that detects that the vehicle is in an understeer state or an oversteer state based on various detection amounts and controls the driving force of the engine in this case to avoid an unstable state of the vehicle There has been a conventional technique related to traction control (see, for example, Patent Document 1).

  Such engine traction control for controlling the driving force of the engine is often used in combination with the brake traction control for controlling the braking force to the driving wheel based on the idling amount of the driving wheel, and restores the stability of the traveling vehicle. It was effective.

Japanese Patent No. 3514329

By the way, when the vehicle is in a traveling state including an acceleration turn, it has been an important issue in the vehicle control technology to stabilize the behavior of the vehicle and to keep the vehicle speed running quickly. However, according to the prior art disclosed in Patent Document 1 described above, since the driving force of the engine is reduced, a reduction in acceleration of the vehicle including turning is inevitable.
That is, in the prior art disclosed in Patent Document 1, the driving force of the engine is reduced during acceleration turning, so that when the vehicle shifts to straight running after turning, the driving force of the engine is returned to the original state. A predetermined time is required for recovery.

That is, according to the prior art disclosed in Patent Document 1, when the vehicle shifts to straight running after a turn, the driving force of the engine can be sufficiently transmitted to the road surface by the drive wheels. Since the driving force remains lowered, the acceleration of the vehicle also remains lowered until the engine returns to the original state.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide vehicle motion control capable of stably driving a vehicle while maintaining the acceleration performance of the vehicle in a traveling state including accelerated turning. To provide an apparatus.

  In order to solve the above-described problem, the structural feature of the vehicle motion control device according to claim 1 is that the driving wheel braking means that applies braking force to the driving wheel of the vehicle and suppresses idling of the driving wheel. An acceleration turning detection unit for detecting an acceleration turning state of the vehicle, an understeer detection unit for detecting an understeering state of the vehicle, and an acceleration turning state of the vehicle detected by the acceleration turning detection unit, and When the understeer state of the vehicle is detected by the understeer detection unit, the driving wheel braking unit suppresses the application of the braking force to the driving wheel inside the turning of the vehicle, and allows the inner driving wheel to idle. And wheel braking change means.

  Here, to suppress the application of the braking force, the start condition of the braking operation on the inner driving wheel is made stricter, the braking force itself on the inner driving wheel is decreased, and the frequency of the braking operation on the inner driving wheel is reduced. All means for allowing idling of the inner drive wheels, such as reducing

  A structural feature of the invention according to claim 2 is the vehicle motion control apparatus according to claim 1, further comprising friction coefficient detecting means for detecting a road surface friction coefficient with the traveling road surface of the vehicle or a correlation value thereof, and driving wheel braking change. As the road surface friction coefficient detected by the friction coefficient detecting means or the correlation value indicated by the correlation value is higher, the means suppresses the application of braking force to the driving wheels on the inner side of the vehicle turning, and It is to allow idling.

  The structural feature of the invention according to claim 3 is that, in the vehicle motion control device according to claim 2, the friction coefficient detecting means detects a lateral motion state quantity of the vehicle as a correlation value of the road surface friction coefficient. is there.

  According to a fourth aspect of the present invention, there is provided a structural feature of the vehicle motion control device according to any one of the first to third aspects, further comprising an accelerator operation amount detecting means for detecting an accelerator operation amount of the vehicle, and changing driving wheel braking. The means is that, as the accelerator operation amount of the vehicle detected by the accelerator operation amount detection means is larger, the braking force is prevented from being applied to the drive wheels inside the turning of the vehicle, and the idling of the inner drive wheels is allowed. is there.

  According to a fifth aspect of the present invention, in the vehicle motion control device according to any one of the first to fourth aspects, the driving wheel braking changing means detects the acceleration turning state of the vehicle by the acceleration turning detection means. And, when the understeer state of the vehicle is detected by the understeer detection means, the application of the braking force to the drive wheels on the outside of the turning of the vehicle by the drive wheel braking means is increased.

  Here, to increase the application of the braking force, the condition for starting the braking operation on the outer driving wheel is relaxed, the braking force on the outer driving wheel itself is increased, and the frequency of the braking operation on the outer driving wheel is increased. All means for reducing the transmission of driving force from the outer driving wheel to the traveling road surface, such as increasing

  A structural feature of the invention according to claim 6 is the vehicle motion control apparatus according to claim 5, further comprising friction coefficient detecting means for detecting a road surface friction coefficient with the traveling road surface of the vehicle or a correlation value thereof, and changing driving wheel braking. The means is to increase the application of the braking force to the outer driving wheel as the road surface friction coefficient detected by the friction coefficient detecting means or the road surface friction coefficient indicated by the correlation value is higher.

  According to a seventh aspect of the present invention, in the vehicle motion control device according to the sixth aspect, the friction coefficient detecting means detects the lateral motion state quantity of the vehicle as a correlation value of the road surface friction coefficient. is there.

  A structural feature of the invention according to claim 8 is the vehicle motion control device according to any one of claims 5 to 7, further comprising accelerator operation amount detection means for detecting an accelerator operation amount of the vehicle, and changes driving wheel braking. The means is that the greater the accelerator operation amount of the vehicle detected by the accelerator operation amount detection means, the greater the braking force applied to the outer drive wheels.

According to the vehicle motion control device of the first aspect, when the acceleration turning state of the vehicle is detected and the understeer state of the vehicle is detected, the braking force is applied to the drive wheels inside the turning of the vehicle. By suppressing the idling of the inner driving wheel that is easy to slip, the engine's surplus driving force that causes the unstable behavior of the vehicle is consumed by the idling of the driving wheel on the inner side of the turn. The vehicle can be made to turn stably without lowering.
Therefore, when the vehicle shifts to straight running after a turn, or after the understeer state is resolved, the surplus driving force of the engine does not decrease, and the vehicle can travel quickly.

According to the vehicle motion control device of the second aspect of the present invention, the higher the road surface friction coefficient indicated by the road surface friction coefficient with the traveling road surface or its correlation value, the more the braking force applied to the drive wheels on the inner side of the turning of the vehicle is suppressed. By allowing idling of the inner driving wheel, it is possible to prevent the surplus driving force of the engine from being consumed by idling of the driving wheel on the inner side of the turn and increasing the understeer state of the vehicle.
In other words, the higher the friction coefficient of the road surface, the more the engine driving force is transmitted from the driving wheel on the outside of the turn to the driving road surface, and the vehicle is likely to be in an understeer state. Consuming power.

  According to the vehicle motion control device of the third aspect, the lateral motion state quantity of the vehicle is detected as the correlation value of the road surface friction coefficient. Thus, normally, the lateral motion state quantity detecting means provided in the vehicle equipped with the vehicle motion control device is used to detect the lateral motion state quantity and to detect the friction coefficient of the traveling road surface in the lateral direction. By substituting the detection of the motion state quantity, the driving force of the engine can be easily consumed according to the friction coefficient of the traveling road surface.

  According to the vehicle motion control apparatus of the fourth aspect, the greater the accelerator operation amount of the vehicle, the more the braking force applied to the drive wheels on the inner side of the turning of the vehicle is suppressed, and the idling of the inner drive wheels is allowed. Thus, the surplus driving force of the engine can be consumed according to the size.

  According to the vehicle motion control apparatus of the fifth aspect, when the acceleration turning state of the vehicle is detected by the acceleration turning detection means and the understeer state of the vehicle is detected by the understeer detection means, the vehicle movement control device is outside the turning of the vehicle. By increasing the application of braking force to the drive wheels, the excess drive force of the engine is released to the inner drive wheels and is consumed by the idling of the inner drive wheels, thereby preventing an increase in the understeer state of the vehicle can do.

  According to the vehicle motion control device of the sixth aspect, the higher the road surface friction coefficient with the traveling road surface detected by the friction coefficient detection means or the correlation value indicated by the correlation value, the higher the braking force applied to the outer drive wheels. By increasing the application, the understeer state of the vehicle can be prevented from increasing according to the magnitude of the friction coefficient of the traveling road surface.

  According to the vehicle motion control device of the seventh aspect, the vehicle motion control device is usually provided in a vehicle on which the vehicle motion control device is mounted by detecting a lateral motion state quantity of the vehicle as a correlation value of the road surface friction coefficient. By using the lateral motion state quantity detection means, the lateral motion state quantity is detected, and the detection of the friction coefficient of the running road surface is replaced by the detection of the lateral motion state quantity. The application of braking force to the outer drive wheel can be increased according to the magnitude of the friction coefficient.

  According to the vehicle motion control device of the eighth aspect, the greater the accelerator operation amount of the vehicle, the greater the braking force applied to the outer driving wheels, thereby increasing the outer driving wheel according to the magnitude of the driving force of the engine. It is possible to increase the braking force applied to the driving wheels.

1 is a block diagram showing a vehicle traveling system equipped with a vehicle motion control device according to Embodiment 1 of the present invention. The figure which showed the brake circuit of the vehicle motion control apparatus shown in FIG. The flowchart which showed the control method of the vehicle motion control apparatus by Embodiment 1. FIG. 3 is a graph showing a diagram showing changes in braking conditions by the control method shown in FIG. 3 in comparison with a normal idling suppression control. The figure which showed typically the driving state of the vehicle by the control method shown in FIG. The graph which represented the diagram which showed the change content of the braking condition by modified embodiment of Embodiment 1 compared with the case of normal idling suppression control The flowchart which showed the control method of the vehicle motion control apparatus by Embodiment 2.

<Embodiment 1>
A vehicle motion control apparatus according to Embodiment 1 of the present invention will be described with reference to FIGS. The vehicle M shown in FIG. 1 is a front-wheel drive (FF) vehicle, and the driving force of the engine 11 as a drive source mounted on the front of the vehicle body is transmitted to the front wheels Wfl and Wfr (corresponding to the drive wheels of the present invention). The format is The vehicle M is not limited to a front-wheel drive vehicle, but may be a vehicle of another drive system such as a rear-wheel drive (FR) vehicle, a four-wheel drive (4WD) vehicle, or a vehicle using an electric motor as a drive source. Good.

  The vehicle M includes a drive / steering system 10 that drives and steers the vehicle M, and a brake system 20 that brakes the vehicle M. The drive / steering system 10 includes an engine 11, a transmission 12, a differential 13, left and right drive shafts 14a and 14b, a throttle valve 15, an accelerator pedal 16, and an engine control ECU 17. The driving force by the engine 11 is transmitted to the drive shafts 14a and 14b via the transmission 12 and the differential 13 to rotate the front wheels Wfl and Wfr.

  The throttle valve 15 is provided with a throttle valve sensor 15a, and the accelerator pedal 16 is provided with an accelerator operation amount sensor 16a (corresponding to the accelerator operation amount detection means of the present invention). It is input to the control ECU 17. The engine control ECU 17 controls the driving force of the engine 11 by controlling the operation of the throttle valve 15 and an injector (not shown) based on the operation amount of the accelerator pedal 16 detected by the accelerator operation amount sensor 16a.

  A steering wheel 18 provided in a driver's seat of the vehicle M is connected to front wheels Wfl and Wfr which are steering wheels via a steering shaft 19 and steers the front wheels Wfl and Wfr according to the operation amount of the steering wheel 18. The steering wheel 18 is connected to a steering angle sensor 18a for detecting the operation amount. The configuration and control of these drive and steering systems 10 are not the subject of the present invention and will not be described in further detail.

  On the other hand, the brake system 20 brakes the vehicle M by applying a hydraulic braking force to each wheel Wfl, Wfr, Wrl, Wrr. The brake system 20 has a basic hydraulic pressure corresponding to a brake pedal 21, a negative pressure booster 22 that boosts the brake operation force applied to the brake pedal 21, and a brake operation force boosted by the negative pressure booster 22. And a master cylinder 23 that generates brake fluid of hydraulic pressure (hydraulic pressure) and supplies the brake fluid to each wheel cylinder WCfl, WCfr, WCrl, WCrr.

  The brake pedal 21 is provided with a brake switch 21a that detects that the brake pedal 21 has been operated. Hereinafter, the wheels Wfl, Wfr, Wrl, Wrr are referred to as wheels Wfl to Wrr, and the wheels cylinders WCfl, WCfr, WCrl, WCrr are referred to as wheel cylinders WCfl to WCrr.

  A reservoir tank 24 that stores brake fluid and replenishes the master cylinder 23 is attached to the master cylinder 23, and the master cylinder 23 and the wheel cylinders WCfl to WCrr are not related to the depression state of the brake pedal 21. A brake actuator 25 (corresponding to the drive wheel braking means of the present invention) that can be applied to the wheel to be controlled by forming a control hydraulic pressure is provided. The brake actuator 25 is electrically connected to a brake control ECU 26 (corresponding to driving wheel braking changing means of the present invention) that controls the brake actuator 25. The brake control ECU 26 is connected to the engine control ECU 17 so as to communicate with each other.

  When the base hydraulic pressure or the control hydraulic pressure is supplied to each wheel cylinder WCfl to WCrr, a pair of brake pads BPfl in which the pistons of the calipers CLfl, CLfr, CLrl, and CLrr including the wheel cylinders WCfl to WCrr are friction members. , BPfr, BPrl, BPrr are pressed. As a result, the braking force is applied by sandwiching the disk rotors DRfl, DRfr, DRrl, DRrr, which are rotating members that rotate integrally with the wheels Wfl to Wrr, from both sides. In this embodiment, the disc type brake is adopted, but a drum type brake may be adopted.

  Wheel speed sensors Sfl, Sfr, Srl, Srr are attached to the wheels Wfl to Wrr, and the wheel speed sensors Sfl, Sfr, Srl, Srr are electrically connected to the brake control ECU 26. Hereinafter, when the wheel speed sensors Sfl, Sfr, Srl, Srr are included, they are referred to as wheel speed sensors Sfl to Srr. The brake control ECU 26 includes a yaw rate sensor 27 that detects the yaw rate of the vehicle M, and a lateral acceleration sensor 28 that detects the lateral acceleration of the vehicle M (the friction coefficient detection means of the present invention, the lateral motion state quantity detection means). Is applicable).

  Further, the accelerator operation amount sensor 16a, the steering angle sensor 18a, and the brake switch 21a described above are connected to the brake control ECU 26. As will be described later, the brake control ECU 26 controls the wheel speed, the yaw rate of the vehicle M, the lateral acceleration generated in the vehicle M (corresponding to the lateral motion state amount of the present invention), the operation amount of the accelerator pedal 16, and the steering. The brake actuator 25 is controlled based on the steering angle by the wheel 18 and the like.

  As shown in FIG. 2, X piping that is applied to many front wheel drive vehicles is adopted as the brake piping of the brake actuator 25. That is, a wheel cylinder WCfr attached to the front right wheel Wfr and a wheel cylinder WCrl attached to the rear left wheel Wrl are connected to the primary chamber 23a of the master cylinder 23 (first brake circuit). A wheel cylinder WCfl attached to the front left wheel Wfl and a wheel cylinder WCrr attached to the rear right wheel Wrr are connected to the chamber 23b (second brake circuit). The present embodiment does not necessarily have to be X piping, and may be front and rear piping.

As shown in FIG. 2, since the piping configuration of the brake actuator 25 is substantially symmetrical on the left and right, the following description will mainly focus on the first brake circuit on the right side, and if necessary, the second brake on the left side. The circuit is also described.
The primary chamber 23a of the master cylinder 23 is connected to the hydraulic pressure control valve 31 of the brake actuator 25 via the main pipeline Lp1. In addition, a check valve 31 a that allows only a flow of brake fluid in a direction from the master cylinder 23 toward the wheel cylinders WCfr and WCrl is provided so as to be arranged in parallel with the hydraulic pressure control valve 31.

  The hydraulic pressure control valve 31 is an electromagnetic valve that operates by energizing a solenoid (not shown), and is connected to the wheel cylinders WCfr and WCrl via the suspension pipes Lp2 and Lp3, respectively. On the undercarriage pipes Lp2 and Lp3, pressure increasing valves 33 and 34 are provided, respectively. In addition, check valves 33 a and 34 a that allow only a flow of brake fluid in a direction from the wheel cylinders WCfr and WCrl toward the master cylinder 23 are provided so as to be arranged in parallel with the pressure increasing valves 33 and 34, respectively.

  The hydraulic pressure control valve 31 is controlled to be switched between a communication state and a differential pressure state by the brake control ECU 26. Normally, when the solenoid is not energized, the hydraulic pressure control valve 31 is in a state in which the master cylinder 23 and the pressure increasing valves 33 and 34 are in communication with each other. While shutting off between the master cylinder 23 and the pressure increasing valves 33, 34, the hydraulic pressure in the suspension lines Lp2, Lp3 on the wheel cylinders WCfr, WCrl side is set to be higher than the hydraulic pressure in the main pipe line Lp1 on the master cylinder 23 side. Can also be maintained at a pressure higher by a predetermined control differential pressure. This control differential pressure is regulated by the brake control ECU 26 according to the control current.

  The pressure-increasing valves 33 and 34 are electromagnetic valves that are operated by energizing a solenoid (not shown). The pressure-increasing valves 33 and 34 are respectively controlled by the brake control ECU 26 to communicate or block the suspension passages Lp2 and Lp3. When the solenoid is in a non-energized state, the pressure increasing valves 33 and 34 are in a communicating state, and when the solenoid is in an energized state, it is in a shut-off state. Hereinafter, when the corresponding pressure increasing valves 35 and 36 are included in the pressure increasing valves 33 and 34 and the suspension passages Ls2 and Ls3 of the second brake circuit, they are referred to as pressure increasing valves 33 to 36.

  One end of relief pipes Lp4, Lp5 is connected between the wheel cylinders WCfr, WCrl and the pressure increasing valves 33, 34 on the suspension pipes Lp2, Lp3, respectively. Are provided with pressure reducing valves 37 and 38, respectively. The other ends of the relief pipes Lp4, Lp5 are both connected to one end of the pump pipe Lp6. The other end of the pump pipe Lp6 is connected to the pressure increasing valves 33, 34 on the undercarriage pipes Lp2, Lp3. It is connected between the hydraulic control valve 31. The pump line Lp6 is provided with a pressure regulating reservoir 45, a hydraulic pump 43, and a damper 47 that alleviates hydraulic pulsation due to the discharge pressure of the hydraulic pump 43.

  The pressure reducing valves 37 and 38 are electromagnetic valves that are operated by energizing a solenoid (not shown), and are controlled by the brake control ECU 26 to communicate or block the relief pipes Lp4 and Lp5. The pressure reducing valves 37 and 38 are cut off when the solenoid is not energized, and are connected when the solenoid is energized. Hereinafter, when the corresponding pressure reducing valves 39, 40 are included in the pressure reducing valves 37, 38 and the relief pipes Ls4, Ls5 of the second brake circuit, they are referred to as pressure reducing valves 37-40.

The hydraulic pump 43 is driven by the electric motor MT, and pumps the brake fluid discharged from the wheel cylinders WCfr, WCrl to the pressure regulating reservoir 45 via the pressure reducing valves 37, 38 again into the suspension lines Lp2, Lp3.
One end of the suction line Lp7 is connected between the pressure regulating reservoir 45 of the pump line Lp6 and the hydraulic pump 43, and the other end of the suction line Lp7 is the primary of the master cylinder 23 on the main line Lp1. It is connected between the chamber 23a and the hydraulic pressure control valve 31. A cut valve 41 is provided in the suction pipe Lp7. The cut valve 41 is an electromagnetic valve that is operated by energizing a solenoid (not shown), and is controlled by the brake control ECU 26 between a communication state and a cutoff state.

  When the solenoid is not energized, the cut valve 41, which is in the cut-off state, is energized to communicate with the solenoid when the brake pedal 21 is not operated, and the hydraulic pump 43 is connected to the master cylinder via the suction line Lp7. 23 brake fluids can be sucked. In this case, the brake fluid sucked by the hydraulic pump 43 is discharged to the undercarriage pipes Lp2 and Lp3, and a braking force is generated in the wheel cylinders WCfr and WCrl.

  A first hydraulic pressure sensor P1 is provided on the main pipeline Lp1 of the first brake circuit. The first hydraulic pressure sensor P1 is connected to the brake control ECU 26, and a detection signal indicating the hydraulic pressure in the primary chamber 23a of the master cylinder 23 is input to the brake control ECU 26. The first hydraulic pressure sensor P1 may be provided on the main pipeline Ls1 of the second brake circuit.

  A second hydraulic pressure sensor P <b> 2 is provided between the wheel cylinder WCfr and the pressure increasing valve 33 on the underline Lp <b> 2 of the first brake circuit. The second hydraulic pressure sensor P2 is connected to the brake control ECU 26, and a detection signal indicating the hydraulic pressure in the wheel cylinder WCfr is input to the brake control ECU 26. The second hydraulic pressure sensor P2 may be provided between the wheel cylinder WCrl and the pressure increasing valve 34 on the undercarriage pipe Lp3.

  Further, a third hydraulic pressure sensor P3 is provided between the wheel cylinder WCfl and the pressure increasing valve 35 on the underline Ls2 of the second brake circuit. The third hydraulic pressure sensor P3 is connected to the brake control ECU 26, and a detection signal indicating the hydraulic pressure in the wheel cylinder WCfl is input to the brake control ECU 26. The third hydraulic pressure sensor P3 may be provided between the wheel cylinder WCrr and the pressure increasing valve 36 on the suspension line Ls3. Hereinafter, when the hydraulic pressure sensors P1, P2, and P3 are included, they are referred to as hydraulic pressure sensors P1 to P3.

  Next, an operation method of the brake system 20 when the vehicle M is in each state will be briefly described. In the brake system 20, when executing a normal brake (an operation mode in which the master cylinder 23 generates a basic hydraulic pressure according to an operation amount of the brake pedal 21), the hydraulic control valves 31 and 32, the pressure increasing valves 33 to 36, The solenoids of the pressure reducing valves 37 to 40 and the cut valves 41 and 42 are all deenergized.

  The brake fluid pressure generated in the primary chamber 23a of the master cylinder 23 according to the operation amount of the brake pedal 21 is transferred to the front right via the main line Lp1, the fluid pressure control valve 31, the underbody line Lp2, and the pressure increasing valve 33. The wheel Wfr is provided to the wheel cylinder WCfr, and is provided to the rear left wheel Wrl via the main pipe Lp1, the hydraulic pressure control valve 31, the undercarriage pipe Lp3, and the pressure increasing valve 34, and is given to the wheel cylinder WCrl. .

  Further, the brake hydraulic pressure generated in the secondary chamber 23b of the master cylinder 23 according to the operation amount of the brake pedal 21 passes through the main line Ls1, the hydraulic pressure control valve 32, the underline Ls2, and the pressure increasing valve 35. Provided to the front left wheel Wfl and given to the wheel cylinder WCfl, and given to the rear right wheel Wrr and given to the wheel cylinder WCrr via the main line Ls1, the hydraulic pressure control valve 32, the undercarriage line Ls3, and the pressure increasing valve 36. Is done.

  When the brake control ECU 26 determines that any one of the wheels Wfl to Wrr has a locking tendency based on the speeds of the wheels Wfl to Wrr detected by the wheel speed sensors Sfl to Srr when the brake pedal 21 is operated, the brake actuator 25, anti-skid (ABS) control is executed.

  For example, when it is determined that the front right wheel Wfr is in a locking tendency, the solenoids of the hydraulic control valves 31, 32, the pressure increasing valves 34, 35, 36, the pressure reducing valves 38, 39, 40, and the cut valves 41, 42 are not turned on. Energized to supply brake fluid pressure from the primary chamber 23a of the master cylinder 23 to the wheel cylinder WCrl provided in the rear left wheel Wrl, and from the secondary chamber 23b of the master cylinder 23 to the front left wheel Wfl and the rear right wheel Wrr. The supply of brake fluid pressure to the wheel cylinders WCfl, WCrr is continued.

On the other hand, the solenoids of the pressure increasing valve 33 and the pressure reducing valve 37 are energized, the communication between the primary chamber 23a of the master cylinder 23 and the wheel cylinder WCfr provided in the front right wheel Wfr is cut off, and the wheel cylinder WCfr is The brake fluid in the wheel cylinder WCfr is discharged to the pressure regulating reservoir 45 in communication with the pressure regulating reservoir 45.
As a result, the brake fluid pressure in the wheel cylinder WCfr is reduced, the braking force generated in the front right wheel Wfr is reduced, the rotation is recovered, and the locking tendency is eliminated. The brake fluid discharged to the pressure adjusting reservoir 45 is circulated by the hydraulic pump 43 to the suspension lines Lp2 and Lp3.

  When driving the front wheels Wfl, Wfr (drive wheels), the brake control ECU 26 tends to slip (idle) any of the drive wheels Wfl, Wfr based on the speeds of the wheels Wfl-Wrr detected by the wheel speed sensors Sfl-Srr. If it is determined that the vehicle is in the position, the brake actuator 25 performs idling suppression control (traction control: TRC) of the drive wheels Wfl, Wfr.

  Using the speed Svfl of the front left wheel Wfl detected by the wheel speed sensor Sfl and the speed Svrl of the rear left wheel (driven wheel) Wrl detected by the wheel speed sensor Srl, the formula: Slfl = (Svfl−Svrl) / Svrl Based on the above, the slip ratio (idling amount) Slfl of the front left wheel Wfl is calculated.

  Further, using the speed Svfr of the front right wheel Wfr detected by the wheel speed sensor Sfr and the speed Svrr of the rear right wheel (driven wheel) Wrr detected by the wheel speed sensor Srr, the formula: Slfr = (Svfr− Based on (Svrr) / Svrr, the idling amount Slfr of the front right wheel Wfr is calculated. The calculation method of the idling amount of the drive wheels Wfl and Wfr is known and is not limited to the above-described method, but is disclosed in Japanese Patent Application Laid-Open Nos. 2007-69871, 10-217933, and the like. Yes. When the calculated idling amount Slfl, Slfr of any of the drive wheels Wfl, Wfr is larger than a predetermined threshold value, it is determined that the drive wheels Wfl, Wfr are in an idling tendency.

The idling amount threshold value described above is shown by a one-dot chain line in FIG. 4 as “normal idling suppression control threshold value”, and as the lateral acceleration Gy of the vehicle M detected by the lateral acceleration sensor 28 increases. It is set to be small.
For example, when it is determined that the front right wheel Wfr tends to idle, the solenoids of the hydraulic pressure control valve 32, the pressure increasing valves 33, 35, 36, the pressure reducing valves 37, 38, 39, 40, and the cut valve 42 are deenergized. Is done. On the other hand, the solenoids of the hydraulic control valve 31, the pressure increasing valve 34, and the cut valve 41 are energized, and the hydraulic pump 43 is driven by the motor MT.

  As a result, the hydraulic pressure control valve 31 enters a differential pressure state, shuts off the master cylinder 23 and the pressure increasing valves 33 and 34, and brake fluid in the reservoir tank 24 is supplied to the master cylinder 23 and the main pipe by the hydraulic pressure pump 43. The air is sucked through the passage Lp1, the suction pipe Lp7 and the cut valve 41, and is given to the wheel cylinder WCfr provided in the front right wheel Wfr through the pump pipe Lp6, the pressure increasing valve 33 and the undercarriage pipe Lp2. A braking force is generated on the right wheel Wfr.

  At this time, the brake fluid in the reservoir tank 24 is also supplied by the hydraulic pump 43 to the undercarriage pipe Lp3. However, since the pressure increasing valve 34 is energized, the wheel cylinder provided in the rear left wheel Wrl. No braking force is applied to the WCrl.

  When the braking force is generated in the front right wheel Wfr and the idling amount decreases and falls below the threshold value shown in FIG. 4, the pressure increasing valve 33 and the pressure reducing valve 37 are energized, and the hydraulic pump 43 and the wheel cylinder WCfr are energized. The wheel cylinder WCfr is communicated with the pressure regulating reservoir 45, and the brake fluid in the wheel cylinder WCfr is discharged to the pressure regulating reservoir 45.

  As a result, the brake fluid pressure in the wheel cylinder WCfr is reduced, and the braking force generated in the front right wheel Wfr is eliminated to restore the rotation. The brake fluid discharged to the pressure adjusting reservoir 45 is circulated by the hydraulic pump 43 to the suspension lines Lp2 and Lp3. The idling suppression control of the drive wheels Wfl and Wfr described above is executed regardless of whether the vehicle M is in a turning state or in a non-turning state, and this control is hereinafter referred to as normal idling suppression control.

  In addition, the brake system 20 is a vehicle detected by wheel speed sensors Sfl to Srr, a brake switch 21a, an accelerator operation amount sensor 16a, a steering angle sensor 18a, a yaw rate sensor 27, a lateral acceleration sensor 28, hydraulic pressure sensors P1 to P3, and the like. Although vehicle stability control (ESC) and brake assist are executed based on the state of M, a detailed description is omitted because there is no direct relationship with the present invention.

  Next, a method of idling suppression control when the vehicle M is turning by the brake control ECU 26 will be described based on the control flowchart shown in FIG. First, detection signal values from the wheel speed sensors Sfl to Srr, the accelerator operation amount sensor 16a, the steering angle sensor 18a, the yaw rate sensor 27, the lateral acceleration sensor 28, and the like are read (step S301).

Next, the yaw rate deviation Δy is calculated from the detected signal value (step S302). The yaw rate deviation Δy is defined as a difference between the actual yaw rate Yr generated in the vehicle M detected by the yaw rate sensor 27 and the target yaw rate Yt. The target yaw rate Yt is obtained from the equation: Yt = V · sin (θ / R) · K / L from the speed V of the vehicle M, the steering angle θ detected by the steering angle sensor 18a, etc. , R is a steering gear ratio of the vehicle M, L is a wheel base of the vehicle M, and K is a related amount of a road surface friction coefficient).
The calculation method of the yaw rate deviation Δy and the target yaw rate Yt is known and is not limited to the above-described method, but is disclosed in Japanese Patent Laid-Open Nos. 7-117645 and 10-44954, which are public patent publications. .

  Next, it is determined whether or not the vehicle M is in an acceleration turning state from the traveling direction acceleration, the steering angle θ, the lateral acceleration Gy, etc. of the vehicle M (step S303: corresponds to acceleration turning detection means of the present invention). ). When it is determined that the vehicle M is not in the accelerated turning state, the control flow ends. When it is determined that the vehicle M is in the acceleration turning state, it is determined whether or not the calculated yaw rate deviation Δy is greater than the first predetermined value Y1 (step S304: corresponds to the understeer detection means of the present invention). When it is determined that the yaw rate deviation Δy is equal to or less than Y1, the control flow is terminated because the vehicle M is considered not to be in the understeer state.

  If it is determined that the yaw rate deviation Δy is greater than the first predetermined value Y1, the vehicle M is considered to be in an understeer state, so is the yaw rate deviation Δy less than the second predetermined value Y2 that is greater than the first predetermined value Y1? It is determined whether or not (step S305). If it is determined that the yaw rate deviation Δy is equal to or greater than Y2, it is considered that the vehicle M is in a strong understeer state, and therefore, spin drift suppression control is executed (step S308).

  The spin / drift suppression control is for applying a turning inward moment to the understeered vehicle M, and is a control method for applying a braking force to the inner wheel of the turning of the rear wheels Wrl and Wrr. This is also disclosed in Japanese Patent Laid-Open No. 7-117645, which is the above-mentioned published patent publication.

  On the other hand, when it is determined in step S305 that the yaw rate deviation Δy is less than Y2, the braking condition is changed in the idling suppression control to the drive wheels Wfl and Wfr (step S306). As shown in FIG. 4, with respect to the threshold of the idling amount when starting the idling suppression control, the threshold value is set for the wheels on the inside of the turning of the driving wheels Wfl, Wfr, compared to the above-described normal idling suppression control. It is increasing.

  As a result, when the vehicle M turns to the left front as shown in FIG. 5, the application of the braking force (IBf) to the driving wheel Wfl on the inside of the turning is suppressed (for example, the start of the braking operation is delayed) and the driving is performed. The idling (IDf) of the wheel Wfl is allowed. In addition, the threshold value of the driving wheels Wfl and Wfr on the outer side of the turn is decreased compared to the normal idling suppression control described above. This encourages the application of braking force (OBf) to the driving wheel Wfr on the outside of the turn (accelerates the start of the braking operation), and consequently suppresses transmission of driving force from the driving wheel Wfr to the road surface (ODf), The excess driving force generated thereby is allowed to escape to the driving wheel Wfl on the inside of the turn. In FIG. 5, the arrow represented by IBf conceptually indicates that the start of the braking operation to the drive wheel Wfl on the inside of the turn is delayed, and the arrow represented by OBf is on the outside of the turn. It is shown conceptually that the start of the braking operation to the drive wheel Wfr is accelerated.

  As shown in FIG. 4, the idling amount threshold value for the drive wheel Wfl on the inside of the turn increases as the lateral acceleration Gy of the vehicle M detected by the lateral acceleration sensor 28 increases. As a result, as the lateral acceleration Gy of the vehicle M increases, the application of the braking force to the drive wheels Wfl on the inside of the turn is delayed, and the idle rotation of the drive wheels Wfl is permitted.

  Further, the idling amount threshold value for the driving wheel Wfr on the outside of the turn decreases as the lateral acceleration Gy of the vehicle M detected by the lateral acceleration sensor 28 increases. Thus, the greater the lateral acceleration Gy of the vehicle M, the faster the braking force is applied to the drive wheels Wfr on the outside of the turn, and the transmission of the drive force from the drive wheels Wfr to the road surface is suppressed.

There is a correlation between the lateral acceleration Gy of the vehicle M and the friction coefficient of the road surface on which the vehicle M travels. When the vehicle M turns, the lateral acceleration Gy of the vehicle M increases as the friction coefficient of the traveling road surface increases. Also grows. Therefore, in the control method described above, the higher the friction coefficient of the road surface on which the vehicle M travels, the more the braking force applied to the drive wheels Wfl on the inside of the turn is suppressed, and the idling of the drive wheels Wfl is allowed. In other words, the higher the friction coefficient of the road surface on which M travels, the more braking force is applied to the drive wheels Wfr on the outside of the turn, and the transmission of the drive force from the drive wheels Wfr to the road surface is suppressed. .
When idling suppression control is executed based on the changed braking condition (step S307), this control flow ends.

  FIG. 6 shows a threshold value of the idling amount when starting idling suppression control of the drive wheels Wfl and Wfr in the modified embodiment of the first embodiment. As shown in FIG. 6, in the present modified embodiment as well, the idling amount of the driving wheels Wfl and Wfr on the inner side of the turn is smaller than that in the normal idling suppression control described above. The threshold value is increased, and the threshold value of the driving wheels Wfl and Wfr on the outer side of the turn is decreased compared to the normal idling suppression control.

  Unlike the first embodiment, in the modified embodiment, the threshold of the idling amount for the drive wheel Wfl on the inside of the turn increases as the operation amount φ of the accelerator pedal 16 detected by the accelerator operation amount sensor 16a increases. . As a result, as the operation amount φ of the accelerator pedal 16 is larger, the application of the braking force to the driving wheel Wfl on the inside of the turn is further suppressed, and the idling of the driving wheel Wfl is allowed.

  Further, the idling amount threshold value for the driving wheel Wfr on the outside of the turn is decreased as the operation amount φ of the accelerator pedal 16 detected by the accelerator operation amount sensor 16a is larger. As a result, as the operation amount φ of the accelerator pedal 16 is larger, the braking force is further applied to the driving wheel Wfr on the outer side of the turn, and the transmission of the driving force from the driving wheel Wfr to the road surface is suppressed and thereby generated. The surplus driving force is released to the driving wheel Wfl on the inside of the turn.

  According to the present embodiment, when the acceleration turning state of the vehicle M is detected and the understeer state of the vehicle M is detected, the application of the braking force to the drive wheels Wfl on the turning inside of the vehicle M is suppressed. By allowing idling of the inner driving wheel Wfl that tends to slip due to insufficient grip force, the driving force of the engine 11 is consumed in the inner driving wheel Wfl, so that the driving force of the engine 11 is not reduced. In addition, the vehicle M can be turned stably.

  Therefore, when the vehicle M shifts to straight running after a turn, or after the understeer state of the vehicle M is eliminated, the driving force of the engine 11 is not reduced, and the vehicle M can run quickly. The present invention functions most effectively when weak understeer is generated in the vehicle M in order to cause the vehicle M to travel stably and promptly.

  In order to eliminate the understeer state of the vehicle M, the braking force is applied to the outer driving wheel Wfr in order to reduce the transmission of the driving force from the driving wheel Wfr on the outer side of the turn where the grip force is easily maintained to the traveling road surface. Even if the consumption of the driving force of the engine 11 in the outer driving wheel Wfr is suppressed, the driving force of the engine 11 can be consumed by idling the inner driving wheel Wfl.

Further, the higher the road surface friction coefficient indicated by the road surface friction coefficient with the traveling road surface or the lateral acceleration Gy that is the correlation value thereof, the more the braking force is applied to the drive wheels Wfl on the inner side of the turning of the vehicle M. By allowing idling of the driving wheel Wfl, it is possible to prevent the excessive driving force of the engine 11 from being consumed by idling of the driving wheel Wfl on the inside of the turn and increasing the understeer state of the vehicle M.
That is, as the friction coefficient of the traveling road surface is higher, the driving force of the engine 11 is transmitted from the driving wheel Wfl on the outer side of the turn to the traveling road surface, and the vehicle M is likely to be in an understeer state, so that the inner driving wheel Wfl is allowed to idle more. Excess driving force of the engine 11 is consumed.

  Further, as the correlation value of the road surface friction coefficient, a lateral acceleration Gy that is a lateral motion state quantity of the vehicle M is detected. As a result, the lateral acceleration Gy is normally detected using the lateral acceleration sensor 28 provided in the vehicle M on which the vehicle motion control device is mounted, and the friction coefficient of the traveling road surface is detected by the lateral motion state quantity. By substituting for detection, the driving force of the engine 11 can be easily consumed according to the magnitude of the friction coefficient of the traveling road surface.

  Further, in the modified embodiment, as the accelerator operation amount of the vehicle M is larger, the braking force applied to the driving wheels Wfl on the inner side of the turning of the vehicle M is suppressed, and the idling of the inner driving wheels Wfl is permitted. The surplus driving force of the engine 11 can be consumed according to the size.

  Further, when the acceleration turning state of the vehicle M is detected and the understeer state of the vehicle M is detected, the application of the braking force to the drive wheels Wfr on the outside of the turning of the vehicle is increased. It is possible to prevent surplus driving force from escaping to the inner driving wheel Wfl and consuming it by idling of the inner driving wheel Wfl, and increasing the understeer state of the vehicle M.

  In addition, the higher the road surface friction coefficient indicated by the road surface friction coefficient with the road surface friction coefficient or the lateral acceleration Gy that is a correlation value thereof, the more the braking force applied to the outer drive wheels Wfr is increased, thereby the friction coefficient of the road surface. The understeer state of the vehicle M can be prevented from increasing according to the size of the vehicle.

Further, by detecting the lateral acceleration Gy, which is the lateral motion state quantity of the vehicle, as the correlation value of the road surface friction coefficient, the lateral motion normally provided in the vehicle M equipped with the vehicle motion control device is detected. By detecting the lateral acceleration Gy using the acceleration sensor 28 and substituting the detection of the friction coefficient of the running road surface with the detection of the lateral motion state quantity, it is possible to easily respond to the magnitude of the friction coefficient of the running road surface. Application of braking force to the outer drive wheel Wfr can be increased.
In the modified embodiment, the greater the accelerator operation amount of the vehicle M, the greater the braking force applied to the outer driving wheels Wfr, thereby increasing the outer driving according to the driving force of the engine 11. Application of braking force to the wheel Wfr can be increased.

<Embodiment 2>
Based on the control flowchart shown in FIG. 7, only the points different from the case of the first embodiment will be described regarding the method of the idling suppression control when the vehicle M turns according to the second embodiment. As shown in FIG. 7, in the control flow of the idling suppression control according to the present embodiment, steps S701 to S704 are exactly the same as steps S301 to S304 in the first embodiment (shown in FIG. 3). .

When it is determined in step S704 shown in FIG. 7 that the yaw rate deviation Δy is larger than the first predetermined value Y1, the braking condition in the idling suppression control of the drive wheels Wfl and Wfr is changed as in the first embodiment. This is performed (step S705).
Thereafter, as in the case of the first embodiment, the idling suppression control is executed based on the changed braking condition, and the braking force is applied to the drive wheels Wfl and Wfr (step S706). Thereafter, the same spin / drift suppression control as in the first embodiment is executed (step S707), and the control flow ends.

<Other embodiments>
The present invention is not limited to the above-described embodiments, and can be modified or expanded as follows.
When the present invention is executed by detecting the acceleration turning state of the vehicle and detecting the understeer state of the vehicle, engine traction control may be used in combination.
In addition, the brake actuator that can be used when implementing the present invention is not limited to the configuration shown in FIG. 2, but may be of a brake-by-wire type or other configurations.

  Further, when the acceleration turning state of the vehicle is detected and the understeer state of the vehicle is detected, as a means for suppressing the application of braking force to the driving wheels inside the turning, the wheel cylinder hydraulic pressure is reduced, The idling of the inner driving wheel may be allowed by reducing the braking force itself to the inner driving wheel or reducing the frequency of the braking operation with respect to the inner driving wheel. Furthermore, these may be executed in combination.

  Further, when the acceleration turning state of the vehicle is detected and the understeer state of the vehicle is detected, as a means for increasing the application of the braking force to the driving wheel outside the turning, the wheel cylinder hydraulic pressure is increased, The transmission of the driving force from the outer driving wheel to the traveling road surface may be reduced by increasing the braking force itself to the outer driving wheel or increasing the frequency of the braking operation for the outer driving wheel. Furthermore, these may be executed in combination.

Moreover, when detecting the friction coefficient of the road surface of a vehicle, you may detect by the method of detecting from a wheel speed and the estimated vehicle body speed of a vehicle, or another method.
Further, the accelerator operation amount of the vehicle may be detected based on a detection signal from a throttle valve sensor or an air flow meter provided on the intake side of the engine.
Further, when the acceleration turning state of the vehicle is detected and the understeer state of the vehicle is detected, it is not always necessary to increase the braking force to be applied to the driving wheel outside the turning. Depending on the state or the like, it may be performed as appropriate.

  Also, instead of the lateral acceleration of the vehicle, the greater the time change of the lateral speed or the lateral acceleration, the more the threshold value of the idling amount for the driving wheel inside the turning is increased, and the time change of the lateral speed or the lateral acceleration is increased. The larger the value, the lower the threshold of the idling amount for the driving wheel on the outer side of the turn.

  In the above-described embodiment, the lateral acceleration Gy is exemplified as the correlation value of the road surface friction coefficient. However, the correlation value is not limited to this, and may be a load on each of the driving wheels Wfl and Wfr of the vehicle M. Good. As a means for detecting the load on each drive wheel Wfl, Wfr of the vehicle M, a load sensor, a height sensor, or the like can be employed.

  Further, as disclosed in the first embodiment, as the lateral acceleration of the vehicle is larger, the control method for allowing idling of the inner driving wheel and increasing the application of the braking force to the outer driving wheel, and a modified embodiment The control method that allows the idling of the inner driving wheel and increases the application of the braking force to the outer driving wheel as the accelerator operation amount is larger may be executed in a superimposed manner.

  In the drawings, 16 is an accelerator pedal, 16a is an accelerator operation amount sensor (accelerator operation amount detection means), 18a is a steering angle sensor, 25 is a brake actuator (drive wheel braking means), and 26 is a brake control ECU (drive wheel braking change means). ), 27 is a yaw rate sensor, 28 is a lateral acceleration sensor (friction coefficient detecting means, lateral movement state quantity detecting means), M is a vehicle, Sfl to Srr are wheel speed sensors, Wfl is a front left wheel (drive wheel), and Wfr is Front right wheel (drive wheel), Wrl indicates a rear left wheel, and Wrr indicates a rear right wheel.

Claims (8)

In a vehicle motion control device provided with driving wheel braking means for applying braking force to driving wheels of a vehicle and suppressing idling of the driving wheels,
Acceleration turning detection means for detecting an acceleration turning state of the vehicle;
An understeer detection means for detecting an understeer state of the vehicle;
When the acceleration turning state of the vehicle is detected by the acceleration turning detection means and the understeer state of the vehicle is detected by the understeer detection means, the driving wheel braking means is located inside the turning of the vehicle. Driving wheel braking changing means for suppressing the application of braking force to the driving wheel and allowing idling of the inner driving wheel;
A vehicle motion control device comprising: Friction coefficient detecting means for detecting a road surface friction coefficient with the road surface of the vehicle or a correlation value thereof,
The driving wheel braking changing means is
As the road surface friction coefficient detected by the friction coefficient detecting means or the road surface friction coefficient indicated by the correlation coefficient is higher, the braking force applied to the driving wheels on the inner side of the turning of the vehicle is suppressed, and the inner driving is performed. The vehicle motion control device according to claim 1, wherein the idling of the wheel is allowed. The friction coefficient detecting means includes
The vehicle motion control device according to claim 2, wherein a lateral motion state quantity of the vehicle is detected as a correlation value of the road surface friction coefficient. An accelerator operation amount detection means for detecting an accelerator operation amount of the vehicle;
The driving wheel braking changing means is
The greater the accelerator operation amount of the vehicle detected by the accelerator operation amount detection means, the more the braking force applied to the drive wheels on the inner side of the turn of the vehicle is suppressed, and the idling of the inner drive wheels is allowed. The vehicle motion control device according to claim 1, wherein the vehicle motion control device is a vehicle motion control device. The driving wheel braking changing means is
When the acceleration turning state of the vehicle is detected by the acceleration turning detection means and the understeer state of the vehicle is detected by the understeer detection means, the driving wheel braking means is located outside the turning of the vehicle. The vehicle motion control device according to any one of claims 1 to 4, wherein application of a braking force to the drive wheels is increased. Friction coefficient detecting means for detecting a road surface friction coefficient with the road surface of the vehicle or a correlation value thereof,
The driving wheel braking changing means is
6. The application of braking force to the outer drive wheels is increased as the road surface friction coefficient detected by the friction coefficient detection means or the road surface friction coefficient indicated by the correlation value is higher. Vehicle motion control device. The friction coefficient detecting means includes
The vehicle motion control device according to claim 6, wherein a lateral motion state quantity of the vehicle is detected as a correlation value of the road surface friction coefficient. An accelerator operation amount detection means for detecting an accelerator operation amount of the vehicle;
The driving wheel braking changing means is
8. The braking force applied to the outer drive wheel is increased as the accelerator operation amount of the vehicle detected by the accelerator operation amount detection unit is larger. The vehicle motion control device described.

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