JP4767815B2 - Vehicle motion control device - Google Patents

Description

  The present invention relates to a vehicle motion control device in which a wheel brake on a side that becomes a turning inner wheel during turning of a vehicle among wheel brakes respectively mounted on left and right front wheels and left and right rear wheels is operated so as to eliminate an understeer state.

In order to eliminate the understeer state at the time of turning of the vehicle, a vehicle motion control device in which wheel brakes mounted on turning inner wheels among left and right front wheels and left and right rear wheels are braked is already known, for example, from Patent Document 1. It has been.
Japanese Patent No. 2583367

  However, in the one disclosed in Patent Document 1 described above, when the brakes are applied to the wheel brakes mounted on the turning inner wheel to eliminate the understeer state, the turning inner wheel side of the left and right rear wheels secures the stability of the vehicle. In addition, the turning inner wheel side of the left and right front wheels does not cause a significant reduction in lateral force due to the addition of braking force, so that the braking force exerted by the wheel brake is controlled so as to be within a preset slip ratio. .

  However, since the slip ratio at which the tire longitudinal force reaches a peak changes depending on the load, slip angle, road friction coefficient, etc., the tire longitudinal force on the rear wheels is the limit in order to ensure vehicle stability during understeer control. It is necessary to set the slip ratio to be determined to be relatively low. In addition, simultaneously with understeer control, when executing deceleration control that actively decelerates the vehicle to reduce the turning radius, the yaw moment required by understeer control is generated by the braking force of the turning inner wheel, and for further deceleration. However, as described above, it is necessary to set the slip ratio for determining that the tire front-rear force of the rear wheel has reached the limit, so that the stability of the vehicle is ensured. It becomes difficult to increase the deceleration of the vehicle.

  The present invention has been made in view of such circumstances, and a vehicle motion control apparatus that can increase vehicle body deceleration while ensuring the stability of the vehicle when performing deceleration control simultaneously with understeer control. The purpose is to provide.

In order to achieve the above object, the invention according to claim 1 is directed to canceling the understeer state of the wheel brake on the side which is the turning inner wheel when turning the vehicle among the wheel brakes mounted on the left and right front wheels and the left and right rear wheels, respectively. the motion control apparatus for a vehicle as allowed to operate, the wheel speed detecting means for detecting individually the wheel speeds of the left and right front wheels and left and right rear wheels, left and right front wheels and based on the wheel speed detected by their wheel speed detecting means and wheel acceleration detecting means for detecting a wheel acceleration of the left and right rear wheels, vehicle speed detecting means for detecting a vehicle speed, and vehicle body acceleration detecting means for detecting a vehicle acceleration, a steering angle detecting means for detecting a steering angle by the steering of the vehicle driver When the yaw rate detecting means for detecting a yaw rate of the vehicle, the lateral acceleration detecting means for detecting a lateral acceleration of the vehicle, each wheel brake Braking torque representative index detecting means and a steering angle obtained the required yaw moment for eliminating the understeer state by the steering angle detecting means for detecting individually the index representing the braking torque generated, resulting in the vehicle speed detecting means The required yaw moment calculating means for calculating based on the vehicle speed and the yaw rate detected by the yaw rate detecting means, and the steering angle detecting means for obtaining the required deceleration for actively decelerating to reduce the turning radius. corner, the vehicle speed and the required deceleration calculating means for calculating on the basis of the lateral acceleration obtained by the vehicle speed and the lateral acceleration detecting means is obtained by the detection means, the request requesting obtained by the yaw moment computing means a yaw moment and the The left and right front wheels turn based on the required deceleration obtained by the required deceleration calculation means. And the brake torque distribution determining means for determining a brake torque distribution wheel and right rear wheels, the wheel acceleration from the resulting wheel acceleration detecting means by subtracting the vehicle body acceleration detected by the vehicle acceleration detecting means acceleration of each wheel calculating the difference, the braking torque correction value determined in order to suppress the excessive braking torque based on the brake torque and the acceleration difference of each wheel based on the index detected by the brake torque representative index detecting means, lock wheels the Rukoto set the upper limit braking torque that can avoid falling into a state, characterized in that it comprises a brake torque upper limit value determining means for determining an upper limit value of the braking torque distribution amount of the brake torque distribution unit for each wheel And

According to a second aspect of the present invention, there is provided a vehicle in which a wheel brake on a side which becomes a turning inner wheel during turning of a vehicle among wheel brakes mounted on the left and right front wheels and the left and right rear wheels is operated so as to eliminate the understeer state. the motion control device, the wheel speed detecting means for detecting individually the wheel speeds of the left and right front wheels and left and right rear wheels, the wheel angular velocity of the left and right front wheels and left and right rear wheels based on the wheel speed detected by their wheel speed detecting means a wheel velocity detecting means for detecting a vehicle speed detecting means for detecting a vehicle speed, a steering angle detecting means for detecting a steering angle by the steering of the vehicle driver, the yaw rate detecting means for detecting a yaw rate of the vehicle, lateral acceleration of the vehicle a lateral acceleration detecting means for detecting the brake bets the individually detecting an index representing the braking torque generated in the wheel brakes And click representative index detecting means, said steering angle obtained by the steering angle detecting means required yaw moment for eliminating the understeer state, on the basis of the yaw rate detected by the vehicle speed and the yaw rate detection means obtained by the vehicle speed detecting means and the required yaw moment computing means for computing the steering angle obtained the required deceleration to actively decelerate so as to reduce the turning radius by the steering angle detecting means, the vehicle speed and the lateral obtained by the vehicle speed detecting means the basis of the request deceleration calculating means for calculating on the basis of the lateral acceleration obtained by the acceleration detecting means, the required yaw moment required yaw moment obtained by the calculating means and requests the deceleration obtained by the requested deceleration calculating means Brake torque distribution that determines the brake torque distribution of the turning inner wheel and the left and right rear wheels of the left and right front wheels A constant unit, said calculating the wheel angular acceleration based on the obtained wheel angular velocity at the wheel velocity detection means, extracting a corresponding wheel angular acceleration on the front wheel of the turning outer side of those wheel angular acceleration as a maximum wheel angular acceleration and, before Symbol turned from outer side of the wheel angular acceleration corresponding to the controlled wheel other than the front wheel by subtracting the maximum wheel angular acceleration calculating the angular acceleration difference for each controlled wheel, with the brake torque representative index detecting means each wheel brake torque based on the index detected, and the braking torque correction value determined in order to suppress the excessive braking torque based on the angular acceleration difference for each of the controlled wheel, avoiding the wheel falling into the locked state the Rukoto set an upper limit brake torque capable of constant upper limit value of the braking torque distribution amount of the brake torque distribution means for each controlled wheel Characterized in that it comprises a Mel brake torque upper limit value determining means.

According to the first aspect of the invention, based on the requested yaw moment obtained by the requested yaw moment calculating means for the understeer control and the requested deceleration obtained by the requested deceleration calculating means for the deceleration control. In determining the brake torque distribution of the turning inner wheel and the left and right rear wheels among the left and right front wheels by the brake torque distribution means, the brake torque upper limit determining means obtains the acceleration difference for each wheel obtained by subtracting the vehicle body acceleration from the wheel acceleration. Determines the possibility of the wheel falling into the locked state, and the brake torque correction value based on the acceleration difference and the brake torque of the wheel, the upper limit brake torque that can prevent the wheel from falling into the locked state is determined. since determining the upper limit value of the braking torque distribution amount of brake torque distribution unit for each wheel determined, When simultaneously deceleration control and Ndasutea control, as the wheel by the addition braking force is not fall into the locked state can be enhanced vehicle deceleration while ensuring the stability of the vehicle.

According to the second aspect of the present invention, based on the required yaw moment obtained by the required yaw moment calculating means for understeer control and the required deceleration obtained by the required deceleration calculating means for deceleration control. Therefore, when determining the brake torque distribution of the turning inner wheel and the left and right rear wheels among the left and right front wheels by the brake torque distribution means, the wheel angular acceleration corresponding to the front wheel on the turning outer wheel side to which the brake is not applied is set to the maximum wheel angular acceleration. extracted as, possible wheel by the pre-Symbol turning outer wheel side of the angular acceleration difference for each controlled wheel from the wheel angular acceleration corresponding to the controlled wheel other than the front wheels obtained by subtracting the maximum wheel angular acceleration falls into the locked state with determining the sex of magnitude, and the brake torque correction value based on the angular acceleration difference, by the braking torque of the wheel, the wheel b Since defining the braking torque of the upper limit that can avoid falling into click state defines the upper limit of the braking torque distribution amount of brake torque distribution means for each controlled wheel, when performing the simultaneous deceleration control and understeer control, brake By applying force, the vehicle body deceleration can be increased while ensuring the stability of the vehicle so that the wheels do not fall into the locked state.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on examples of the present invention shown in the accompanying drawings.

  1 to 5 show a first embodiment of the present invention, FIG. 1 is a diagram showing a drive system and a brake system of a front engine / front drive vehicle, and FIG. 2 is a diagram showing a configuration of a brake device. 3 is a block diagram showing a configuration for performing understeer control and deceleration control in the control unit, FIG. 4 is a diagram showing a map used in the required deceleration calculation means, and FIG. 5 is one example of the configuration of the brake torque upper limit value setting means. FIG.

First, in FIG. 1, this vehicle is a front engine / front drive (FF) vehicle, and a power unit P composed of an engine E and a transmission T is provided at the front portion of the vehicle body 1 with a left front wheel W _FL and a right wheel as drive wheels. It is mounted to drive the front wheel _WFR . The left and right front wheels W _FL and W _FR are equipped with left and right front wheel brakes B _FL and B _FR , and the left rear wheel W _RL and the right rear wheel W _RR which are driven wheels are the left and right rear wheels. The wheel brakes B _RL and B _RR are mounted, and the wheel brakes B _FL , B _FR , B _RL and B _RR are, for example, disc brakes.

The brake fluid pressure corresponding to the depression operation of the brake pedal 3 is output from the first and second output ports 2A and 2B provided in the tandem master cylinder M. The output ports 2A and 2B are brake fluid pressures. Connected to the circuit 4, the brake fluid pressure from the brake fluid pressure circuit 4 is applied to the wheel brakes B _FL , B _FR , B _RL , B _RR . In the brake fluid pressure circuit 4, the wheel brakes B _FL by being controlled by the control unit CA, B _FR, B _RL, are those brake fluid pressure exerting on the B _RR is adjusted, the control unit CA , the wheel brakes _{B FL, B FR, B RL} , the wheel brakes B _FL as an index representing the brake torque B _RR exerts, B _FR, B _RL, brake detecting individually brake pressure of B _RR Brake pressure detectors 5 _FL , 5 _FR , 5 _RL , 5 _RR as torque representative index detecting means, wheel speed detecting means 6 _{FL for} detecting the wheel speed of each wheel W _FL , W _FR , W _RL , W _RR , respectively _{6 FR, 6 RL, 6 RR} , the steering angle detecting means 7 for detecting a steering angle δ, which is operated by the steering wheel H, to detect the lateral acceleration α of the yaw rate detecting means 8 for detecting a yaw rate gamma, and the vehicle the vehicle The detected value of lateral acceleration detecting means 9 are input.

In FIG. 2, the brake fluid pressure circuit 4 basically has an X-pipe type brake circuit configuration, and the first fluid corresponding to the left front wheel brake B _FL and the right rear wheel brake B _RR. pressure passage 10A and a second hydraulic pressure line 10B corresponding to the right front wheel brake B _FR and the left rear wheel brake B _RL, first and second reservoirs 11A and reservoir R with the master cylinder M is different , 11B and the first and second hydraulic pressure passages 10A, 10B that are driven by a common single electric motor 13 and pump the brake fluid in the first and second reservoirs 11A, 11B and discharge them to the first and second hydraulic pressure paths 10A, 10B. The second pumps 14A, 14B, the normally open solenoid valve 15A interposed between the first output port 2A of the master cylinder M and the first hydraulic pressure passage 10A, and the second output port 2B of the master cylinder M A normally open solenoid valve 15B interposed between the second hydraulic pressure passage 10B and a normally closed solenoid valve 16A interposed between the suction side of the first pump 14A and the first output port 2A of the master cylinder M. When a normally closed solenoid valve 16B which is interposed between the second output port 2B on the suction side and the master cylinder M of the second pump 14B, disposed between the first fluid pressure passage 10A and the left front wheel brake B _FL Left front wheel brake pressure adjusting means 17 _FL , right rear wheel brake pressure adjusting means 17 _RR provided between the first hydraulic pressure path 10A and the right rear wheel brake B _RR , the second hydraulic pressure path 10B and the right front wheel. Right front wheel brake pressure adjusting means 17 _FR provided between the vehicle wheel brakes B _FR, and a left rear wheel brake pressure adjusting means 17 _RL provided between the second hydraulic pressure passage 10B and the left rear wheel wheel brake B _RL. .

The left front wheel brake pressure adjusting means 17 _FL includes a normally-open electromagnetic valve 18 _FL provided between the first hydraulic pressure path 10A and the left front wheel wheel brake B _FL , and the first reservoir 11A and the left front wheel wheel brake B _FL. a normally closed solenoid valve 19 _FL provided, connected in parallel to tolerable to the normally open electromagnetic valves 18 _FL to the flow of the brake fluid from the front left wheel brake B _FL side to the first hydraulic pressure passage 10A side And a check valve 20 _FL .

According to such left front wheel brake pressure adjusting means 17 _FL , when the brake pedal 3 is depressed, the normally open solenoid valve 18 _FL is opened when the normally closed solenoid valve 19 _FL is closed. the first output hydraulic pressure of the port 2A is to act on the left front wheel brake B _FL, also normally open electromagnetic valves 18 _FL and the normally closed electromagnetic valve 19 _FL together close when the left front wheel brake by can hold the brake fluid pressure of the B _FL, further brake hydraulic pressure of the left front wheel brake B _FL by opening the normally closed solenoid valves 19 _FL with closed normally open electromagnetic valve 18 _FL Can be decompressed.

The right rear wheel brake pressure adjusting means 17 _RR includes a normally open electromagnetic valve 18 _RR provided between the first hydraulic pressure passage 10A and the right rear wheel wheel brake B _RR , and the first reservoir 11A and the right rear wheel wheel brake. The normally closed solenoid valve 19 _RR provided between the B _RR and the right rear wheel brake B _RR side is allowed to flow from the brake fluid to the first hydraulic pressure passage 10A side to the normally open solenoid valve 18 _RR . The left front wheel brake pressure adjusting means 17 _FL is constituted by a check valve 20 _RR connected in parallel and controlling the opening and closing of the normally open solenoid valve 18 _RR and the normally closed solenoid valve 19 _RR. Similarly, it is possible to control switching right rear wheel brake B _RR intensifier, retention and reduced pressure and.

The right front wheel brake pressure adjusting means 17 _FR is provided between the normally open solenoid valve 18 _FR provided between the second hydraulic pressure passage 10B and the right front wheel wheel brake B _{FR, and} between the second reservoir 11B and the right front wheel wheel brake B _FR. a normally closed solenoid valve 19 _FR provided, connected from the right front wheel brake B _FR side in parallel with the second liquid allowed to normally open electromagnetic valve 18 _FR circulation of brake fluid to the passage 10B side that is intended to be constituted by a check valve 20 _FR, by controlling the opening and closing of the normally open electromagnetic valve 18 _FR and the normally closed electromagnetic valve 19 _FR, the left front wheel brake pressure control means 17 _FL and the right rear wheel Like the braking pressure adjusting means 17 _RR, it can be controlled by switching the right front wheel brake B _FR intensifier, holding and pressure reduction.

The left rear wheel brake pressure adjusting means 17 _RL includes a normally open electromagnetic valve 18 _RL provided between the second hydraulic pressure path 10B and the left rear wheel wheel brake B _RL , and the second reservoir 11B and the left rear wheel wheel brake. The normally closed solenoid valve 19 _RL provided between B _RL and the left rear wheel brake B _RL side to allow the brake fluid to flow from the second hydraulic pressure path 10 B side to the normally open solenoid valve 18 _RL The left front wheel brake pressure adjusting means 17 _FL is constituted by a check valve 20 _RL connected in parallel and controlling the opening and closing of the normally open solenoid valve 18 _RL and the normally closed solenoid valve 19 _RL. Similarly to the right rear wheel brake pressure adjusting means 17 _RR and the right front wheel brake pressure adjusting means 17 _FR , it is possible to switch the pressure increase, hold and pressure reduction of the left rear wheel wheel brake B _RL .

Further, the first output port 2A of the master cylinder M and the first hydraulic pressure passage 10A are shut off by closing the normally open solenoid valve 15A, and the normally closed solenoid valve 16A is opened to open the first output of the master cylinder M. The first pump 14A is operated in a state where the port 2A is in communication with the suction side of the first pump 14A, and the normally open solenoid valve 18 _{FL in the} left front wheel brake pressure adjusting means 17 _FL and the right rear wheel brake pressure adjusting means 17 _RR is operated. , 18 _RR and normally closed solenoid valves 19 _FL , 19 _RR are opened / closed to increase, hold and reduce the pressure of the left front wheel brake B _FL and the right rear wheel brake B _RR during non-brake operation. It is also possible to control.

Further, the second output port 2B of the master cylinder M and the second hydraulic pressure passage 10B are shut off by closing the normally open solenoid valve 15B, and the normally closed solenoid valve 16B is opened to open the second output of the master cylinder M. The second pump 14B is operated in a state where the port 2B is in communication with the suction side of the second pump 14B, and the normally open solenoid valve 18 _{FR in the} right front wheel brake pressure adjusting means 17 _FR and the left rear wheel brake pressure adjusting means 17 _RL . , 18 _RL and normally closed solenoid valve 19 _FR , 19 _RL are controlled to open / close, thereby increasing, holding and reducing the pressure of the right front wheel brake B _FR and the left rear wheel brake B _RL during non-brake operation. It is also possible to control.

The control unit CA operates so as to eliminate the understeer state of the wheel brake of the turning inner wheel among the wheel brakes B _FL , B _FR , B _RL , B _RR mounted on the left and right front wheels and the left and right rear wheels, respectively, when the vehicle is turning. allowed to a understeer control, left, right front wheel brake B _FL, the wheel brakes B _FL, except for turning outer of _{B FR, B FR, B RL} , actively so as to reduce the turning radius by actuated the B _RR It is possible to control the operation of the brake hydraulic circuit 4 so as to perform the deceleration control for decelerating automatically, and the configuration for performing the understeer control and the deceleration control in the control unit CA will be described next. To do.

In FIG. 3, the control unit CA has brake pressure detectors 5 _FL , 5 _FR , 5 _RL , 5 _RR , wheel speed detecting means 6 _FL , 6 _FR , 6 _RL , 6 for understeer control and deceleration control. Detection values of _RR , steering angle detection means 7, yaw rate detection means 8 and lateral acceleration detection means 9 are input.

Thus, the control unit CA detects the wheel acceleration detecting means for detecting the wheel accelerations of the left and right front wheels and the left and right rear wheels based on the wheel speeds detected by the wheel speed detecting means 6 _FL , 6 _FR , 6 _RL and 6 _RR. 55 _FL , 55 _FR , 55 _RL , 55 _RR , vehicle speed detecting means 56 for detecting the vehicle speed, vehicle body acceleration detecting means 57 for detecting the vehicle body acceleration, and the required yaw moment for eliminating the understeer state are detected by the steering angle. Requested yaw moment calculating means 58 for calculating based on the steering angle δ obtained by the means 7, the vehicle speed obtained by the vehicle speed detecting means 56, and the yaw rate γ detected by the yaw rate detecting means 8, and positively reducing the turning radius. The required deceleration for decelerating the vehicle is determined by the steering angle δ obtained by the steering angle detecting means 7, the vehicle speed obtained by the vehicle speed detecting means 56, and the lateral acceleration. The required deceleration calculating means 59 for calculating based on the lateral acceleration α obtained by the degree detecting means 9, the required yaw moment obtained by the required yaw moment calculating means 58 and the required deceleration calculating means 59. Obtained by the brake torque distribution determining means 60 for determining the brake torque distribution of the turning inner wheel and the left and right rear wheels among the left and right front wheels based on the required deceleration, and the wheel acceleration detecting means 55 _FL , 55 _FR , 55 _RL , 55 _RR Based on wheel acceleration, vehicle body acceleration detected by the vehicle body acceleration detecting means 57 and brake pressure detected by the brake pressure detectors 5 _FL , 5 _FR , 5 _RL , 5 _RR , braking by the brake torque distribution means 60 is performed. Brake torque upper limit determining means 61 for determining the upper limit value of the torque distribution amount.

The wheel acceleration detection means 55 _{FL to} 55 _RR obtains the wheel accelerations of the left and right front wheels and the left and right rear wheels by differentiating the wheel speeds detected by the wheel speed detection means 6 _{FL to} 6 _RR. Calculates the vehicle speed based on the wheel speed detected by the wheel speed detection means 6 _{FL to} 6 _RR , and the vehicle body acceleration detection means 57 differentiates the vehicle speed by differentiating the vehicle speed obtained by the vehicle speed detection means 56. To get.

  The requested yaw moment calculating means 58 determines the target yaw rate intended by the driver based on the steering angle δ obtained by the steering angle detecting means 7 and the vehicle speed obtained by the vehicle speed detecting means 56, and the yaw rate detecting means 8 Based on the deviation of the detected yaw rate γ from the target yaw rate, a required yaw moment for promoting turning is calculated.

  The requested deceleration calculation means 59 determines the target yaw rate intended by the driver based on the steering angle δ obtained by the steering angle detection means 7 and the vehicle speed obtained by the vehicle speed detection means 56, and the vehicle speed detection means 56 A target turning radius is obtained based on the obtained vehicle speed and the target yaw rate. Here, in the understeer state, the lateral acceleration α detected by the lateral acceleration detecting means 9 can be regarded as the limit lateral acceleration α, and the required deceleration calculating means 59 is the lateral acceleration detecting means 9. Based on the detected lateral acceleration α and the target turning radius, the vehicle speed when the target turning radius travels at the lateral acceleration α is determined as the limit vehicle speed, and the actual vehicle speed obtained by the vehicle speed detection means 56 and the limit A coefficient K1 indicating the degree of overspeed based on the vehicle speed is calculated as {K1 = (limit vehicle speed−actual vehicle speed) / limit vehicle speed}, and the required deceleration corresponding to the coefficient K1 is calculated based on the map shown in FIG. Ask.

The brake torque distribution determining means 60 is configured to brake the turning inner wheel and the left and right rear wheels among the left and right front wheels based on the requested yaw moment obtained by the requested yaw moment calculating means 58 and the requested deceleration obtained by the requested deceleration calculating means 59. Signals for determining torque distribution and controlling the operation of left front wheel brake pressure adjusting means 17 _FL , right rear wheel brake pressure adjusting means 17 _RR , right front wheel brake pressure adjusting means 17 _FR and left rear wheel brake pressure adjusting means 17 _RL The upper limit value of the brake torque distribution amount at that time is determined by the brake torque upper limit value determining means 61.

The brake torque upper limit determining means 61 has the configuration shown in FIG. 5 for each of the left and right front wheels and the left and right rear wheels, and detects the vehicle body acceleration from the wheel acceleration obtained by one of the wheel acceleration detecting means 55 _{FL to} 55 _RR. An acceleration difference obtained by subtracting the vehicle body acceleration obtained by the means 57 is obtained at the first addition point 62. Thus, when the vehicle decelerates, the wheel acceleration is a wheel deceleration having a minus sign, and the vehicle body acceleration is a vehicle deceleration having a minus sign. The greater the possibility that the wheel is locked, the greater the minus Thus, an acceleration difference having the following sign is obtained at the first addition point 62. The output of the first addition point 62 is input to the first multiplier 63. The first multiplier 63 obtains the rotational angular velocity by multiplying the acceleration difference by (1 / wheel radius). It is done. The output of the first multiplier 63 is input to the second multiplier 64. The second multiplier 64 multiplies the rotational angular acceleration obtained by the first multiplier 63 by the wheel inertia moment for each wheel. Thus, the corrected brake torque can be obtained. Thus, the wheel inertia moment of the driving wheel, in this embodiment, the wheel inertia moment of the left and right front wheels is preset including the weight of the wheel and the weight of the transmission T and the drive shaft. The second multiplier 64 obtains a corrected brake torque having a negative sign with a larger absolute value as the possibility of falling is greater.

The brake torque upper limit determining means 61 calculates the brake torque of each wheel based on the brake pressure detected by the brake pressure detectors 5 _{FL to} 5 _RR. The corrected brake torque obtained by the second multiplier 64 is subtracted from one of the torques. Thus, the brake torque has a minus sign, and when there is a high possibility that the wheel is locked, the corrected brake torque obtained by the second multiplier 64 has a large absolute value and a minus sign. The absolute value of the brake torque output from the second addition point 65 is small. On the other hand, when the wheel is not likely to be locked, the corrected brake torque obtained by the second multiplier 64 has a plus sign, and the absolute value of the brake torque output from the second addition point 65 is growing.

  The output of the second addition point 65 is input to the brake torque distribution determination unit 60 as the upper limit value of the brake torque distribution amount in the brake torque distribution unit 60, and there is a high possibility that the wheel will be locked. The absolute value of the upper limit value of the brake torque distribution amount becomes smaller.

  Next, the operation of the first embodiment will be described. In order to execute the deceleration control so as to reduce the required yaw moment obtained by the required yaw moment calculating means 58 for the understeer control during the turning of the vehicle and the turning radius. On the basis of the required deceleration obtained by the required deceleration calculating means 59, the brake torque distribution means 60 determines the brake torque distribution for the turning inner wheel and the left and right rear wheels among the left and right front wheels. The brake torque upper limit determination means 61 for determining the upper limit value of the brake torque distribution amount at 60 determines whether the wheel is likely to be locked due to the acceleration difference obtained by subtracting the vehicle body acceleration from the wheel acceleration. The wheel is locked by the brake torque correction value based on the acceleration difference and the brake torque of the wheel. Defining an upper limit value of the braking torque distribution amount of brake torque distribution unit 60 defines the upper limit braking torque that can avoid falling into the state.

  Therefore, when the deceleration control is performed simultaneously with the understeer control, the vehicle body deceleration can be increased while ensuring the stability of the vehicle by preventing the wheels from being locked by applying the braking force.

  FIGS. 6 and 7 show a second embodiment of the present invention. FIG. 6 is a block diagram showing a configuration for performing understeer control and deceleration control in the control unit, and FIG. 7 is a brake torque upper limit value determining means. It is a flowchart which shows the determination procedure in.

First, in FIG. 6, the control unit CB includes brake pressure detectors 5 _FL , 5 _FR , 5 _RL , 5 _RR , wheel speed detecting means 6 _FL , 6 _FR , 6 _RL , in order to perform understeer control and deceleration control. 6 _RR , steering angle detection means 7, yaw rate detection means 8, and lateral acceleration detection means 9 detection values are input.

Thus, the control unit CB detects the wheel angular velocity detecting means 66 _FL , 66 _FR , 66 for detecting the angular velocities of the left and right front wheels and the left and right rear wheels based on the wheel speeds detected by the wheel speed detecting means 6 _{FL to} 6 _{RR. RL} , 66 _RR , vehicle speed detection means 56 for detecting the vehicle speed, the required yaw moment for eliminating the understeer state, the steering angle δ obtained by the steering angle detection means 7, the vehicle speed obtained by the vehicle speed detection means 56, and A required yaw moment calculating means 58 for calculating based on the yaw rate γ detected by the yaw rate detecting means 8 and a required deceleration for actively decelerating to reduce the turning radius can be obtained by the steering angle detecting means 7. Required deceleration calculated based on the steering angle δ, the vehicle speed obtained by the vehicle speed detecting means 56 and the lateral acceleration α obtained by the lateral acceleration detecting means 9 Based on the requested yaw moment obtained by the computing means 59 and the requested yaw moment computing means 58 and the requested deceleration obtained by the requested deceleration computing means 59, the brake torque of the turning inner wheel and the left and right rear wheels among the left and right front wheels Brake torque distribution determining means 60 for determining the distribution, wheel angular speed obtained by the wheel angular speed detecting means 66 _{FL to} 66 _RR , and brake pressure detected by the brake pressure detectors 5 _FL , 5 _FR , 5 _RL , 5 _RR Brake torque upper limit value determining means 67 for determining an upper limit brake torque distribution amount in the brake torque distribution means 60 by determining an upper limit brake torque that can prevent the wheels from falling into a locked state.

The wheel angular velocity detection means 66 _{FL to} 66 _RR obtains the angular velocity ω for each wheel by dividing the differential value of the wheel speed detected by the wheel speed detection means 6 _{FL to} 6 _RR by the wheel radius. The brake torque upper limit determining means 67 calculates a brake torque T for each wheel based on the brake pressure detected by the brake pressure detectors 5 _{FL to} 5 _RR , and based on the angular velocity ω and the brake torque T. The upper limit value of the brake torque distribution amount is determined according to the procedure shown in FIG. In FIG. 7, the suffix i changes for each of the left and right front wheels and the left and right rear wheels, the brake torque T has a negative sign, and the angular acceleration dω also has a negative sign when decelerating.

In FIG. 7, in step S1, the angular acceleration dω _i for each wheel is calculated by differentiation of the angular velocity ω _i , and in step S2, the angular acceleration dω _max that is maximum (absolute value is minimum) is extracted. Thus, since the brake is not applied to the turning outer wheel side of the left and right front wheels, the wheel deceleration of the turning outer wheel in the left and right front wheels is almost the vehicle body deceleration, and the angular acceleration is the maximum compared to the other wheels, The angular acceleration of the wheel having a wheel deceleration equivalent to the vehicle body deceleration is extracted as the maximum angular acceleration dω _max .

In step S3, an angular acceleration difference dω _i ′ (= dω _i −dω _max ) of the brake control target wheel is calculated as an amount corresponding to the slip rate increase amount of the brake control target wheel. This angular acceleration difference dω _i ′ is a negative value, and an increase in the absolute value means that the wheel is decelerating more than the deceleration of the vehicle body.

In step S4, it is determined whether or not the angular acceleration difference dω _i ′ is less than a preset first threshold A (value of 0 or less). If dω _i ′ <A, the wheel is locked. Since there is a possibility of falling into a state, the process proceeds to step S5. In step S5 after calculating the integral value ω _i ′ (= dω _i ′ · dt + ω _i ′) of the angular acceleration difference dω _i ′ in step S5, the integral value ω _i ′ is set to the second threshold B (0 If it is {ω _i ′ ≧ B}, the process proceeds to step S7. If {ω _i ′ <B}, the process proceeds to step S10.

  Here, at the beginning of braking, since the braking force cannot be exerted unless the angular acceleration difference of each wheel is allowed, it is necessary to allow the angular acceleration difference of each wheel. Since the wheel angular acceleration difference is generated, the determination in step S6 is necessary.

In step S7, the excessive brake torque T _0i is set to “0”. When additional braking torque is determined not to excessive here, it is necessary to determine the braking torque increment T _ai in order to increase the deceleration determines the braking torque increment T _ai and "E (<0)". Incidentally, when the brake torque increment value T _ai is not set, it is the same as E = 0, and the generation of the braking force is impossible.

In step S8 after step S7, the brake torque upper limit value T _Li is determined, and the brake torque upper limit value T _Li is set as {T _Li = T _i −T _oi + T _ai }.

If it is determined in step S4 that {dω _i ′ ≧ A}, it is determined that there is no possibility that the wheel is locked, and the process proceeds to step S9, where the angular acceleration difference dω _i ′ and the integrated value ω _i ′ of the angular acceleration difference are determined. Is reset to “0”, and the process proceeds to step S7.

If {ω _i ′ <B} in step S6, the process proceeds to step S10. In step S10, the state where the wheel is decelerating more than the deceleration of the vehicle body occurs because the brake torque is excessive. The excess brake torque T _0i is calculated as {T _0i = K2 · I _i · dω _i }. Here, K2 is a weighting coefficient, and the absolute value of the excess brake torque T _0i is smaller than the brake torque T _i . I _i is a wheel inertia moment for each wheel, and is set in advance as described in the second multiplier 64 of FIG. Further, in step S10, the brake torque increment value T _ai is set to “0”, and the process proceeds from step S10 to step S8.

According to such a brake torque upper limit determining means 67, the angular acceleration of the wheel having the wheel deceleration equivalent to the vehicle body deceleration is set to the maximum angular acceleration dω _max , and the maximum angular acceleration dω _max and the control target are determined. 'it is calculated, and the brake torque T _i of each wheel, the angular acceleration difference d [omega _i' which is a deviation of the angular acceleration d [omega _i angular acceleration difference d [omega _i braking torque distribution by the braking torque correction value determined on the basis of the The upper limit value of the brake torque distribution amount in the means 60 is determined.

  In the second embodiment, as in the first embodiment, when the deceleration control is performed simultaneously with the understeer control, the stability of the vehicle is ensured by preventing the wheels from being locked by the addition of the braking force. Vehicle deceleration can be increased.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the present invention described in the claims. Is possible.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the 1st Example and shows the drive system and brake system of a front engine front drive vehicle. It is a figure which shows the structure of a brake device. It is a block diagram which shows the structure for performing understeer control and deceleration control among control units. It is a figure which shows the map used with a request | requirement deceleration calculating means. It is a figure which shows a part of structure of a brake torque upper limit value setting means. It is a block diagram which shows a 2nd Example and shows the structure for performing understeer control and deceleration control among control units. It is a flowchart which shows the determination procedure in a brake torque upper limit value determination means.

5 _FL , 5 _FR , 5 _RL , 5 _RR ··· Brake pressure detector 6 _FL , 6 _FR , 6 _RL , 6 _RR · · Wheel speed detector 7 ··· Steering angle detector 8: Yaw rate detection means 9: Lateral acceleration detection means _55FL , _55FR , _55RL , _55RR ... Wheel acceleration detection means 56 ... Vehicle speed detection means 57 ... Vehicle acceleration detection means 58 ... Request yaw moment calculation means 59 ... Request deceleration calculation means 60 ... Brake torque distribution determination means 61, 67 ... Brake torque upper limit determination means 66 _FL , 66 _FR , 66 _RL , 66 _RR ..Wheel angular velocity detection means _BFL , _BFR , _BRL , _BRR ... Wheel brake

Claims (2)

Out of the wheel brakes (B _FL , B _FR , B _RL , B _RR ) mounted on the left and right front wheels and the left and right rear wheels, the wheel brake on the side that becomes the turning inner wheel when turning the vehicle is operated to eliminate the understeer state In the vehicle motion control device,
Wheel speed detection means (6 _FL , 6 _FR , 6 _RL , 6 _RR ) for individually detecting the wheel speeds of the left and right front wheels and the left and right rear wheels ;
Wheel acceleration detection means (55 _FL , 55 _FR , 55 _RL) for individually detecting the wheel accelerations of the left and right front wheels and the left and right rear wheels based on the wheel speeds detected by the wheel speed detection means (6 _{FL to} 6 _RR ) and 55 _RR),
Vehicle speed detection means (56) for detecting the vehicle speed ;
Vehicle acceleration detection means (57) for detecting vehicle acceleration ;
Steering angle detection means (7) for detecting the steering angle by the steering of the vehicle driver ;
Yaw rate detection means (8) for detecting the yaw rate of the vehicle ;
Lateral acceleration detection means (9) for detecting the lateral acceleration of the vehicle ;
Brake torque representative index detecting means (5 _FL , 5 _FR , 5 _RL , 5 _RR ) for individually detecting an index representative of the brake torque generated in each wheel brake (B _{FL to} B _RR ) ;
The required yaw moment for eliminating the understeer state is the steering angle obtained by the steering angle detection means (7), the vehicle speed obtained by the vehicle speed detection means (56), and the yaw rate detected by the yaw rate detection means (8). and the required yaw moment calculation means for calculating, based (58),
The required deceleration for actively decelerating to reduce the turning radius is obtained by the steering angle obtained by the steering angle detecting means (7), the vehicle speed obtained by the vehicle speed detecting means (56), and the lateral acceleration detecting means. Requested deceleration calculating means (59) for calculating based on the lateral acceleration obtained in (9) ;
Based on the required yaw moment obtained by the required yaw moment calculating means (58) and the required deceleration obtained by the required deceleration calculating means (59), the brake torque distribution of the turning inner wheel and the left and right rear wheels among the left and right front wheels the brake torque distribution determining means for determining (60),
By subtracting the vehicle body acceleration detected by the vehicle body acceleration detection means (57) from the wheel acceleration obtained by the wheel acceleration detection means (55 _{FL to} 55 _RR ), an acceleration difference for each wheel is calculated, and the brake torque Based on the brake torque of each wheel based on the index detected by the representative index detection means (5 _{FL to} 5 _RR ) , and the brake torque correction value determined to suppress excessive brake torque based on the acceleration difference for each wheel . by Rukoto defines the upper limit braking torque of the wheel can avoid falling into the locked state, the brake torque upper limit value determination for determining the upper limit of the brake torque distribution amount of brake torque distribution means (60) for each wheel vehicle motion control apparatus, characterized in that it comprises a means (61). Out of the wheel brakes (B _FL , B _FR , B _RL , B _RR ) mounted on the left and right front wheels and the left and right rear wheels, the wheel brake on the side that becomes the turning inner wheel when turning the vehicle is operated to eliminate the understeer state In the vehicle motion control device,
Wheel speed detection means (6 _FL , 6 _FR , 6 _RL , 6 _RR ) for individually detecting the wheel speeds of the left and right front wheels and the left and right rear wheels ;
Wheel angular speed detecting means (66 _FL , 66 _FR , 66 _RL) for individually detecting the wheel angular speeds of the left and right front wheels and the left and right rear wheels based on the wheel speeds detected by the wheel speed detecting means (6 _{FL to} 6 _RR ) and 66 _RR),
Vehicle speed detection means (56) for detecting the vehicle speed ;
Steering angle detection means (7) for detecting the steering angle by the steering of the vehicle driver ;
Yaw rate detection means (8) for detecting the yaw rate of the vehicle ;
Lateral acceleration detection means (9) for detecting the lateral acceleration of the vehicle ;
Brake torque representative index detecting means (5 _FL , 5 _FR , 5 _RL , 5 _RR ) for individually detecting an index representative of the brake torque generated in each wheel brake (B _{FL to} B _RR ) ;
The required yaw moment for eliminating the understeer state is the steering angle obtained by the steering angle detection means (7), the vehicle speed obtained by the vehicle speed detection means (56), and the yaw rate detected by the yaw rate detection means (8). and the required yaw moment calculation means for calculating, based (58),
The required deceleration for actively decelerating to reduce the turning radius is obtained by the steering angle obtained by the steering angle detecting means (7), the vehicle speed obtained by the vehicle speed detecting means (56), and the lateral acceleration detecting means. Requested deceleration calculating means (57) for calculating based on the lateral acceleration obtained in (9) ;
Based on the required yaw moment obtained by the required yaw moment calculating means (58) and the required deceleration obtained by the required deceleration calculating means (59), the brake torque distribution of the turning inner wheel and the left and right rear wheels among the left and right front wheels the brake torque distribution determining means for determining (60),
Based on the wheel angular velocity obtained by the wheel angular velocity detecting means (66 _{FL to} 66 _RR ), the wheel angular acceleration for each wheel is calculated, and the wheel angular acceleration corresponding to the front wheel on the turning outer wheel side among the wheel angular accelerations. was extracted as the maximum wheel angular acceleration, and calculates the angular acceleration difference before Symbol turning outer wheel side of the from the wheel angular acceleration corresponding to the controlled wheel other than the front wheel by subtracting the maximum wheel angular acceleration for each controlled wheel, the brake defined in order to suppress the excessive braking torque based wheel brakes torque based on the index detected by the brake torque representative index detecting means (5 _FL ~5 _RR), and the angular acceleration difference for each of the controlled wheel by the torque correction value, by Rukoto defines the upper limit braking torque of the wheel can avoid falling into the locked state, the brake of the brake torque distribution means (60) Brake torque upper limit determining means (67) for determining an upper limit value of the key torque distribution amount for each wheel to be controlled.

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