JP6349129B2 - Brake control device for vehicle - Google Patents

Description

  The present invention relates to a vehicle brake control device, and more particularly, to brake control corresponding to a split road in which a friction coefficient of a ground road surface is greatly different on the left and right.

  Conventionally, as a vehicle brake control device capable of executing brake control corresponding to a split road, the right yaw rate is detected so that the actual yaw rate detected by the yaw rate sensor approaches the target yaw rate set based on the steering angle and the vehicle speed. What sets the difference of the brake fluid pressure concerning a wheel brake is known (refer to patent documents 1).

JP 2013-193479 A

  By the way, as a target yaw rate setting method, a steering angle map in which a target yaw rate value is set in advance in association with a steering angle and a vehicle speed map in which a target yaw rate value is set in advance in association with a vehicle speed are used. There is a way. Specifically, in this method, the smaller one of the target yaw rate calculated using the steering angle map and the target yaw rate calculated using the vehicle speed map is set as the target yaw rate.

  However, in this method, for example, when the target yaw rate is calculated using the steering angle map when the vehicle speed is a predetermined speed (a speed at which the vehicle speed map is not selected), the vehicle When the speed changes and the vehicle speed map is selected, the target yaw rate changes greatly, which may make it difficult for the driver to perform the steering operation smoothly.

  Therefore, an object of the present invention is to provide a vehicle brake control device that can make a driver's steering operation smooth by suppressing a change in a target yaw rate to be small.

In order to solve the above problems, a vehicle brake control device according to the present invention includes an actual yaw rate acquisition unit that acquires an actual yaw rate detected by a yaw rate sensor, and a target yaw rate so that the vehicle turns to the road surface on the high friction coefficient side. The target yaw rate setting means to be set and the brake fluid pressure of the wheel brake on the high friction coefficient side and the brake fluid pressure of the wheel brake on the low friction coefficient side on the split road where the friction coefficient of the ground contact surface of the wheel is different from the right and left by a predetermined amount or more. Differential pressure setting means for setting the difference so that the actual yaw rate follows the target yaw rate, and the target yaw rate setting means sets the target yaw rate smaller as the steering angle increases, and the vehicle speed The larger the value, the smaller the amount of change in the target yaw rate relative to the amount of change in the steering angle .

According to this configuration, the map for calculating the target yaw rate does not change suddenly even when the vehicle speed changes while the target yaw rate is calculated based on the steering angle. A change can be suppressed small and a driver's steering operation can be made smooth. In addition, when the vehicle speed is high, the target yaw rate changes with a small amount of change. For example, during high-speed driving, the change in the target yaw rate can be suppressed to a smaller level, and the driver's steering operation can be made smoother. Can do.

  In the above-described configuration, the target yaw rate setting means may be configured to set the target yaw rate based on a map or function in which a value of the target yaw rate is set in advance in association with the steering angle and the vehicle speed.

  According to this, the target yaw rate can be suitably set by the map or the function.

  According to the present invention, since the change in the target yaw rate can be suppressed to a small level, the driver's steering operation can be made smooth.

It is a lineblock diagram of vehicles provided with a brake control device for vehicles concerning an embodiment. It is a block diagram which shows the structure of a hydraulic unit. It is a block diagram which shows the structure of a control part. It is a map in which a target yaw rate value is set in advance in association with the steering angle and the vehicle speed. It is a block diagram which shows the structure of a differential pressure setting means. It is a map which shows the relationship between the steering angle for setting a feedforward differential pressure, and the differential pressure based on a steering angle. It is a map which shows the relationship between the ratio of a vehicle speed and a target yaw rate for setting feedforward differential pressure, and the differential pressure based on the ratio of a vehicle speed and a target yaw rate. It is a map which shows the relationship between vehicle speed and differential pressure for setting differential pressure. It is a flowchart which shows the process at the time of antilock brake control by a control part.

Next, embodiments will be described in detail with reference to the drawings as appropriate.
As shown in FIG. 1, the vehicle brake control device A according to the present embodiment is a device that appropriately controls the braking force applied to each wheel W of the vehicle CR. The vehicle brake control device A mainly includes a hydraulic unit 10 provided with an oil passage and various parts, and a control unit 100 for appropriately controlling various parts in the hydraulic unit 10.

  Each wheel W is provided with a wheel brake FL, RR, RL, FR, and each wheel brake FL, RR, RL, FR is braked by a hydraulic pressure supplied from a master cylinder MC as a hydraulic pressure source. Is provided. Master cylinder MC and wheel cylinder H are each connected to hydraulic unit 10. In normal times, the brake hydraulic pressure generated in the master cylinder MC in response to the depression force of the brake pedal BP (driver's braking operation) is supplied to the wheel cylinder H after being controlled by the control unit 100 and the hydraulic unit 10. Is done.

  The control unit 100 includes a pressure sensor 91 that detects the pressure of the master cylinder MC, a wheel speed sensor 92 that detects the wheel speed of each wheel W, a steering angle sensor 93 that detects the steering angle θ of the steering ST, and a vehicle. A yaw rate sensor 94 that detects an actual yaw rate Y that is an actual yaw rate of the CR is connected. The control unit 100 includes, for example, a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and an input / output circuit, and inputs from the sensors 91 to 94 and the ROM The control is executed by performing various arithmetic processes based on the programs and data stored in. Details of the control unit 100 will be described later.

  As shown in FIG. 2, the hydraulic unit 10 is disposed between the master cylinder MC and the wheel brakes FL, RR, RL, FR. The two output ports M1, M2 of the master cylinder MC are connected to the inlet port 10a of the hydraulic unit 10, and the outlet port 10b is connected to each wheel brake FL, RR, RL, FR. In normal times, the oil pressure path of the brake pedal BP is transmitted to the wheel brakes FL, RR, RL, and FR because the oil passage communicates from the inlet port 10a to the outlet port 10b in the hydraulic unit 10. It has become so.

  The hydraulic pressure unit 10 is provided with four inlet valves 1, four outlet valves 2, and four check valves 1a corresponding to the wheel brakes FL, RR, RL, FR. The hydraulic unit 10 is also provided with a reservoir 3, a pump 4, and an orifice 5a in each of the hydraulic pressure paths 11 and 12 corresponding to the output ports M1 and M2 of the master cylinder MC. The hydraulic unit 10 is provided with a common motor 6 for driving the pumps 4.

  The inlet valve 1 is a normally open proportional solenoid valve provided between each wheel brake FL, RR, RL, FR and the master cylinder MC. The inlet valve 1 is normally opened to allow the brake hydraulic pressure to be transmitted from the master cylinder MC to the wheel brakes FL, RR, RL, FR. In addition, the inlet valve 1 is blocked by the control unit 100 when the wheel W is about to be locked, thereby cutting off the hydraulic pressure transmitted from the brake pedal BP to each wheel brake FL, RR, RL, FR.

  The outlet valve 2 is a normally closed electromagnetic valve provided between each wheel brake FL, RR, RL, FR and the reservoir 3. Although the outlet valve 2 is normally closed, the hydraulic pressure applied to the wheel brakes FL, RR, RL, FR is applied to the reservoir 3 by being released by the control unit 100 when the wheel W is about to be locked. Let it go.

  The check valve 1a is connected to each inlet valve 1 in parallel. This check valve 1a is a valve that only allows the brake fluid to flow from the wheel brakes FL, RR, RL, FR side to the master cylinder MC side, and the inlet valve when the input from the brake pedal BP is released. Even when 1 is closed, the flow of brake fluid from each wheel brake FL, RR, RL, FR side to the master cylinder MC side is allowed.

The reservoir 3 has a function of temporarily storing brake fluid that is released when each outlet valve 2 is opened.
The pump 4 is provided between the reservoir 3 and the master cylinder MC, and has a function of sucking the brake fluid stored in the reservoir 3 and returning the brake fluid to the master cylinder MC through the orifice 5a. ing.

  The inlet valve 1 and the outlet valve 2 control the brake fluid pressure of the wheel cylinders H of the wheel brakes FL, RR, RL, FR by the control unit 100 controlling the open / close state. For example, in a normal state in which the inlet valve 1 is open and the outlet valve 2 is closed, if the brake pedal BP is depressed, the hydraulic pressure from the master cylinder MC is transmitted to the wheel cylinder H as it is, and the pressure increases. When the valve 1 is closed and the outlet valve 2 is opened, the brake fluid flows out from the wheel cylinder H to the reservoir 3 side to be in a reduced pressure state, and when both the inlet valve 1 and the outlet valve 2 are closed, the brake fluid pressure is increased. It becomes a holding state to be held.

Next, details of the control unit 100 will be described.
The control unit 100 is a device that performs control to stabilize the vehicle by controlling the hydraulic unit 10 and applying the braking force set to each wheel brake FL, RR, RL, FR. Therefore, as shown in FIG. 3, the control unit 100 includes a vehicle speed acquisition unit 111, a steering angle acquisition unit 112, an actual yaw rate acquisition unit 113, a target yaw rate setting unit 121, and an antilock brake control unit 130. The split path determination means 140, the differential pressure setting means 150, the control execution means 160, and the storage means 190 are mainly provided.

  The vehicle speed acquisition unit 111 is a unit that acquires information on the wheel speed WS (pulse signal of the wheel speed sensor 92) from the wheel speed sensor 92, and calculates and acquires the vehicle speed V by a known method. The calculated vehicle speed V is output to the target yaw rate setting means 121, the antilock brake control means 130, and the differential pressure setting means 150.

  The steering angle acquisition unit 112 is a unit that acquires information on the steering angle θ from the steering angle sensor 93. The acquired steering angle θ is output to the target yaw rate setting means 121 and the differential pressure setting means 150. In the present specification, the steering angle θ is positive when the steering ST is operated in the direction in which the vehicle CR turns to the low friction coefficient side on the split road.

  The actual yaw rate acquisition unit 113 is a unit that acquires information on the actual yaw rate Y that is the actual yaw rate of the vehicle CR from the yaw rate sensor 94. The acquired actual yaw rate Y is output to the differential pressure setting means 150. In this specification, the actual yaw rate Y and the target yaw rate YT, which will be described later, are positive in the direction in which the vehicle CR turns to the high friction coefficient side on the split road.

  The target yaw rate setting means 121 is a means for setting a target yaw rate YT such that the vehicle CR turns to the road surface on the high friction coefficient side based on the vehicle speed V and the steering angle θ. Specifically, the target yaw rate setting means 121 sets the target yaw rate YT to be smaller as the steering angle θ increases, and changes the amount of change in the target yaw rate YT relative to the amount of change in the steering angle θ according to the vehicle speed V. ing. That is, the target yaw rate setting means 121 sets the target yaw rate so that the target yaw rate YT gradually decreases with a gradient corresponding to the vehicle speed V as the steering angle θ increases. More specifically, the target yaw rate setting means 121 sets the target yaw rate based on a map in which the value of the target yaw rate YT is preset in association with the steering angle θ and the vehicle speed V as shown in FIG.

  In the map of FIG. 4, the target according to the steering angle θ when the vehicle speed V is the first speed V1, the second speed V2, the third speed V3, the fourth speed V4, the fifth speed V5, and the sixth speed V6. Each yaw rate YT is set. Here, the magnitude relationship of the vehicle speed V is V1 <V2 <V3 <V4 <V5 <V6. Specifically, when the vehicle speed V is the first speed V1, the target yaw rate YT is determined to be a constant value YT6 in a range where the steering angle θ is 0 or less. When the steering angle θ is between 0 and a predetermined value θ1, the target yaw rate YT is determined so as to gradually decrease from the constant value YT6 with a relatively large initial decrease rate G61. When the steering angle θ is between the predetermined value θ1 and the predetermined value θ2, the target yaw rate YT is determined so as to gradually decrease at a medium-term decrease rate G62 smaller than the initial decrease rate G61. In a range where the steering angle θ is larger than the predetermined value θ2, the target yaw rate YT is determined so as to gradually become smaller at a later-stage decrease rate G63 that is smaller than the medium-term decrease rate G62.

  When the vehicle speed V is the second speed V2, the target yaw rate YT is determined to be a constant value YT5 smaller than the constant value YT6 at the first speed V1 when the steering angle θ is 0 or less. . When the steering angle θ is between 0 and the predetermined value θ1, the target yaw rate YT is determined so as to gradually decrease from the constant value YT5 with an initial decrease rate G51 smaller than the initial decrease rate G61 at the first speed V1. It has been. When the steering angle θ is between the predetermined value θ1 and the predetermined value θ2, the target yaw rate YT is an intermediate decrease rate G52 that is smaller than the initial decrease rate G51 and smaller than the intermediate decrease rate G62 at the first speed V1. It is decided to gradually become smaller. In a range where the steering angle θ is larger than the predetermined value θ2, the target yaw rate YT is smaller than the medium-term decrease rate G52, and the late-term decrease rate G53 is substantially the same as the late-term decrease rate G63 at the first speed V1. It is decided to gradually become smaller.

  When the vehicle speed V is the third speed V3, the target yaw rate YT is determined to be a constant value YT4 smaller than the constant value YT5 at the second speed V2 in the range where the steering angle θ is 0 or less. . When the steering angle θ is between 0 and a predetermined value θ1, the target yaw rate YT is determined so as to gradually decrease from the constant value YT4 with an initial decrease rate G41 smaller than the initial decrease rate G51 at the second speed V2. It has been. When the steering angle θ is between the predetermined value θ1 and the predetermined value θ2, the target yaw rate YT is an intermediate decrease rate G42 that is smaller than the initial decrease rate G41 and smaller than the intermediate decrease rate G52 at the second speed V2. It is decided to gradually become smaller. In a range where the steering angle θ is larger than the predetermined value θ2, the target yaw rate YT is smaller than the medium-term decrease rate G42, and the late-term decrease rate G43 is substantially the same as the late-term decrease rate G53 at the second speed V2. It is decided to gradually become smaller. Specifically, the late reduction rate G43 is the same as the late reduction rate G53 when the steering angle θ ranges from the predetermined value θ2 to the predetermined value θ3, and the late reduction rate G53 when the steering angle θ is greater than the predetermined value θ3. The rate of decrease is smaller than that.

  When the vehicle speed V is the fourth speed V4, the target yaw rate YT is determined to be a constant value YT3 smaller than the constant value YT4 at the third speed V3 in the range where the steering angle θ is 0 or less. . When the steering angle θ is between 0 and the predetermined value θ1, the target yaw rate YT is determined so as to gradually decrease from the constant value YT3 with an initial decrease rate G31 smaller than the initial decrease rate G41 at the third speed V3. It has been. In a range where the steering angle θ is larger than the predetermined value θ1, the target yaw rate YT is gradually smaller at an intermediate decrease rate G32 that is smaller than the initial decrease rate G31 and smaller than the intermediate decrease rate G42 at the third speed V3. Thus, after it becomes 0 (after θ3), it is determined to be maintained even if the steering angle θ increases.

  When the vehicle speed V is the fifth speed V5, the target yaw rate YT is determined to be a constant value YT2 smaller than the constant value YT3 at the fourth speed V4 in the range where the steering angle θ is 0 or less. . When the steering angle θ is between 0 and a predetermined value θ1, the target yaw rate YT is determined to gradually decrease from the constant value YT2 with an initial decrease rate G21 that is smaller than the initial decrease rate G31 at the fourth speed V4. It has been. When the steering angle θ is between the predetermined value θ1 and the predetermined value θ2, the target yaw rate YT is an intermediate decrease rate G22 that is smaller than the initial decrease rate G21 and smaller than the intermediate decrease rate G32 at the fourth speed V4. It is decided to gradually become smaller. In a range where the steering angle θ is larger than the predetermined value θ2, the target yaw rate YT is determined to be zero.

  When the vehicle speed V is the sixth speed V6, the target yaw rate YT is determined to be a constant value YT1 smaller than the constant value YT2 at the fifth speed V5 when the steering angle θ is 0 or less. . When the steering angle θ is between 0 and a predetermined value θ1, the target yaw rate YT is determined so as to gradually decrease from the constant value YT1 with an initial decrease rate G11 smaller than the initial decrease rate G21 at the fifth speed V5. It has been. In a range where the steering angle θ is larger than the predetermined value θ1, the target yaw rate YT is determined to be zero.

  That is, when the vehicle speed V is the first speed (for example, the first speed V1), the target yaw rate setting means 121 sets the target yaw rate YT to the first gradient (for example, the initial decrease rate G61) as the steering angle θ increases. When the vehicle speed V is a second speed greater than the first speed (for example, the second speed V2), the target yaw rate YT is smaller than the first gradient as the steering angle θ increases. It is set so as to gradually decrease with two gradients (for example, initial reduction rate G51). Specifically, when the steering angle θ is in the range from 0 to θ2, the reduction rate is set to decrease as the vehicle speed V increases. Further, in the range where the steering angle θ is larger than θ2, the decrease rate is set to become smaller as the vehicle speed V increases, or to be the same value regardless of the vehicle speed V.

  Further, the target yaw rate setting means 121 calculates the target yaw rate YT by linear interpolation when the vehicle speed V is other than the speed described above. For example, when the vehicle speed V is 30 km / h, the target yaw rate setting unit 121 performs linear interpolation based on the steering angle θ, the second speed V2 graph, and the third speed V3 graph, thereby performing the target yaw rate. YT is calculated.

  Then, when the target yaw rate setting unit 121 sets the target yaw rate YT, the target yaw rate setting unit 121 outputs the set target yaw rate YT to the differential pressure setting unit 150.

  The anti-lock brake control means 130 determines, for each wheel W, whether or not to execute the anti-lock brake control by a known method based on the wheel speed WS and the vehicle speed V, and the liquid during the anti-lock brake control. This is means for determining for each wheel W an instruction for pressure control (instruction on whether the hydraulic pressure in the wheel cylinder H is to be in a pressure-increasing state, a holding state, or a pressure-reducing state). Information indicating that the anti-lock brake control is to be executed is output to the split road determination unit 140, and the determined hydraulic pressure control instruction is output to the control execution unit 160.

  The split road determination means 140 is a means for determining whether or not the split road has a friction coefficient different from the left and right by a predetermined amount or more when the antilock brake control is executed. The method for determining the split road is not particularly limited. As an example, when the anti-lock brake control is executed, the wheel W indicating the maximum value (the value at which the deceleration is least) among the decelerations of the wheels W. Can be determined as a split road when the difference between the decelerations of the left and right wheels W is equal to or greater than the second threshold. Further, when the split road determination unit 140 determines that the road is a split road, the split road determination unit 140 determines which of the left and right wheels W is on the high friction coefficient side and which is on the low friction coefficient side. As an example, of the left and right wheels W, the wheel W having the smaller deceleration is determined as the high friction coefficient side, and the wheel W having the larger deceleration is determined as the low friction coefficient side. Information indicating that it is a split road is output to the differential pressure setting means 150.

  The differential pressure setting means 150 is a means for setting a braking force difference that is a difference between the braking force of the wheel brake on the high friction coefficient side and the braking force of the wheel brake on the low friction coefficient side on the split road. In this embodiment, the differential pressure setting means 150 is a difference between the brake fluid pressure of the wheel brake on the high friction coefficient side and the brake fluid pressure of the wheel brake on the low friction coefficient side as a value corresponding to the braking force difference. The differential pressure DP is set so that the actual yaw rate Y follows the target yaw rate YT. Here, the actual yaw rate used for the right wheel control is positive in the clockwise direction when the vehicle CR is viewed from above, and the actual yaw rate used for the left wheel control is the counterclockwise direction when the vehicle CR is viewed from above. Is positive. The actual yaw rate Y to be compared with the target yaw rate YT is the actual yaw rate used for controlling the wheel on the high friction side. For the above-described control, the differential pressure setting unit 150 includes a feedforward differential pressure calculation unit 151, a deviation calculation unit 152, a feedback differential pressure calculation unit 153, and a differential pressure calculation unit 156, as shown in FIG. Has mainly.

Feedforward pressure calculation unit 151, based on the steering angle θ and the vehicle speed V and the target yaw rate YT, a means for calculating the feedforward differential pressure DP _FF. Specifically, the feedforward differential pressure DP _FF is calculated by adding the differential pressure based on the vehicle speed V and the target yaw rate YT to the differential pressure based on the steering angle θ. FIG. 6 is a map for setting the differential pressure based on the steering angle θ, and is determined so that the differential pressure increases as the steering angle θ increases. FIG. 7 is a map for setting a differential pressure based on the vehicle speed V and the target yaw rate YT, and the differential pressure increases as the ratio (YT / V) between the vehicle speed V and the target yaw rate YT increases. It is decided so. The calculated feedforward differential pressure DP _FF is output to the differential pressure calculation unit 156.

  The deviation calculation unit 152 is a unit that calculates a deviation ΔY (= Y−YT) between the actual yaw rate Y output from the actual yaw rate acquisition unit 113 and the target yaw rate YT output from the target yaw rate setting unit 121. . The calculated deviation ΔY is output to the feedback differential pressure calculation unit 153.

The feedback differential pressure calculation unit 153 is means for calculating a feedback differential pressure DP _FB for setting the differential pressure DP by PID (Proportional Integral Derivative) control so that the actual yaw rate Y follows the target yaw rate YT. Specifically, feedback differential pressure DP _FB includes P term (proportional gain × current deviation ΔY), I term (previous I term + (integral gain × current deviation ΔY)), and D term (differential gain × (Previous deviation ΔY−current deviation ΔY)) is added. The calculated feedback differential pressure DP _FB is output to the differential pressure calculation unit 156.

The differential pressure calculation unit 156 is a means for calculating the differential pressure DP. Specifically, the differential pressure DP is calculated based on the vehicle speed V and a preset map until a predetermined time T1 elapses after it is determined that the road is a split road. FIG. 8 is a map for setting the differential pressure DP from when it is determined that the road is a split road until the predetermined time T1 elapses. The higher the vehicle speed V, the smaller the differential pressure DP. It has been decided. On the other hand, after a predetermined time T1 after it is determined that the split road is elapsed, it calculates the differential pressure DP based on the feedforward differential pressure DP _FF and the feedback differential pressure DP _FB. Specifically, the differential pressure DP is calculated by adding the feedforward differential pressure DP _FF and the feedback differential pressure DP _FB . The calculated differential pressure DP is output to the control execution means 160.

  Based on the hydraulic pressure control instruction determined by the anti-lock brake control means 130 and the differential pressure DP set by the differential pressure setting means 150, the control execution means 160 uses a known method to cause the wheel brakes FL, RR, RL, It is means for controlling the brake fluid pressure of FR. Specifically, for the wheel brake that executes the antilock brake control, the hydraulic pressure unit 10 is controlled based on the hydraulic pressure control instruction determined by the antilock brake control means 130. Also, when it is determined that the road is split, if the difference between the brake fluid pressure of the wheel brake on the high friction coefficient side and the brake fluid pressure of the wheel brake on the low friction coefficient side is likely to exceed the differential pressure DP The hydraulic pressure unit 10 is controlled such that the brake fluid pressure of the wheel brake on the high friction coefficient side becomes a value obtained by adding the differential pressure DP to the brake fluid pressure of the wheel brake on the low friction coefficient side. The specific control of the hydraulic unit 10 is well known and will not be described in detail. However, in brief, the current output to the inlet valve 1 and the outlet valve 2 is adjusted, and the motor 6 is turned on as necessary. It controls to drive and drive the pump 4.

  The storage unit 190 is a unit that appropriately stores programs, constants, maps, calculation results, and the like necessary for the operation of the control unit 100.

  Next, processing during antilock brake control by the control unit 100 of the vehicle brake control device A will be described with reference to FIG. Note that the process of FIG. 9 is repeated for each control cycle.

  First, the control unit 100 acquires the wheel speed WS from the wheel speed sensor 92, the steering angle θ from the steering angle sensor 93, and the actual yaw rate Y from the yaw rate sensor 94 (S101). Next, the control unit 100 calculates the vehicle speed V from the wheel speed WS and calculates the target yaw rate YT based on the vehicle speed V and the steering angle θ (S102). Then, the antilock brake control means 130 determines a hydraulic pressure control instruction for the antilock brake control (S111).

Next, the split road determination unit 140 determines whether or not the ground road surface of the wheel W is a split road (S112).
When it is determined that the road is not a split road (S112, NO), the control execution means 160 controls the hydraulic pressure unit 10 based on the hydraulic pressure control instruction of the antilock brake control, and controls the brake hydraulic pressure of the wheel brake. (S131).

  If it is determined in step S112 that the road is a split road (YES), the differential pressure setting unit 150 determines whether or not a predetermined time T1 has elapsed since it was determined that the road is a split road (S121). When the predetermined time T1 has not elapsed (S121, NO), the differential pressure setting means 150 sets the differential pressure DP from the map of FIG. 8 based on the vehicle speed V (S122).

On the other hand, in step S121, when the predetermined time T1 has elapsed (YES), the differential pressure setting means 150, the vehicle speed V, and calculates the feedforward differential pressure DP _FF based on the steering angle θ and the target yaw rate YT (S124) . The differential pressure setting means 150 calculates a deviation ΔY between the actual yaw rate Y and the target yaw rate YT (S125), and calculates a feedback differential pressure DP _FB by PID control based on the deviation ΔY (S126).

Then, the differential pressure setting means 150 calculates the sum of the feedforward differential pressure DP _FF and the feedback differential pressure DP _FB as the differential pressure DP (S127).

  When the differential pressure DP is calculated, the control execution means 160 controls the hydraulic pressure unit 10 based on the differential pressure DP and the hydraulic pressure control instruction of the antilock brake control, and controls the brake hydraulic pressure of the wheel brake. (S131). Specifically, the brake fluid pressure of the wheel brake on the low friction coefficient side is controlled based on the hydraulic control instruction of the anti-lock brake control, and the brake fluid pressure and the low friction coefficient of the wheel brake on the high friction coefficient side are controlled. If the difference from the brake fluid pressure of the wheel brake on the side is likely to exceed the differential pressure DP, the brake fluid pressure of the wheel brake on the high friction coefficient side becomes the differential pressure on the brake fluid pressure of the wheel brake on the low friction coefficient side. The brake fluid pressure of the wheel brake on the high friction coefficient side is controlled so as to be a value obtained by adding DP.

  Next, a change in the target yaw rate YT when the driver steers in the positive direction on the split road will be described.

  For example, when it is determined by the control unit 100 that the vehicle CR is traveling at the third speed V3 as a split road, when the driver steers the steering in the positive direction, FIG. As indicated by a broken line, the target yaw rate YT initially decreases so as to gradually decrease along the initial decrease rate G41 corresponding to the third speed V3. Thereafter, when the vehicle speed V becomes lower than the third speed V3, the target yaw rate YT changes smoothly at a moderate decrease rate by linear interpolation.

  When the vehicle speed V becomes the second speed V2, the target yaw rate YT gradually decreases along the decreasing rate corresponding to the second speed V2. Thereafter, similarly, the target yaw rate YT changes smoothly at a gradual decrease rate by decreasing along a linear interpolation or a decrease rate corresponding to the first speed V1.

  Since the target yaw rate YT changes smoothly on the split road in this manner, the change in the actual yaw rate generated so as to follow the target yaw rate YT also becomes smooth, so that the driver can smoothly perform a steering operation that cancels the actual yaw rate. Can be done.

As described above, in the present embodiment, the following effects can be obtained in addition to the effects described above.
When the vehicle speed V is a high speed (for example, the sixth speed V6), the target yaw rate YT changes with a small gradient (for example, the initial decrease rate G11) when the steering angle θ is increased. The change in the yaw rate YT can be further reduced, and the driver's steering operation can be made smoother.

  In addition, this invention is not limited to the said embodiment, It can utilize with various forms so that it may illustrate below.

  In the embodiment, the target yaw rate YT is set based on the map. However, the present invention is not limited to this, and the target yaw rate YT may be calculated based on a function (formula) corresponding to the map, for example.

  In the above embodiment, the vehicle brake control device A using the brake fluid is illustrated, but the present invention is not limited to this. For example, the electric brake that generates the brake force by the electric motor without using the brake fluid. It may be a vehicle brake control device for controlling the device.

94 Yaw rate sensor 113 Actual yaw rate acquisition means 121 Target yaw rate setting means 150 Differential pressure setting means A Vehicle brake control device FL, RR, RL, FR Wheel brake W Wheel Y Actual yaw rate YT Target yaw rate θ Steering angle

Claims (2)

An actual yaw rate acquisition means for acquiring the actual yaw rate detected by the yaw rate sensor;
Target yaw rate setting means for setting the target yaw rate so that the vehicle turns to the road surface on the high friction coefficient side;
The difference between the brake fluid pressure of the wheel brake on the high friction coefficient side and the brake fluid pressure of the wheel brake on the low friction coefficient side on the split road where the friction coefficient of the ground contact road surface of the wheel differs by a predetermined amount or more on the left and right is the actual yaw rate Differential pressure setting means for setting so as to follow the target yaw rate,
The target yaw rate setting means sets the target yaw rate to be smaller as the steering angle increases, and reduces the amount of change in the target yaw rate with respect to the amount of change in the steering angle as the vehicle speed increases. Control device.   2. The vehicle brake control device according to claim 1, wherein the target yaw rate setting unit sets the target yaw rate based on a map or function in which a value of the target yaw rate is set in advance in association with the steering angle and the vehicle speed. .

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