JP6806666B2 - Braking force control system - Google Patents

Description

The present invention relates to a braking force control system.

In Patent Document 1, when the distance and the relative speed between the own vehicle and the obstacle are detected and it is determined that there is a possibility of contact with the obstacle but the risk is low, the engine brake is first applied. It is described that the brakes are generated and then the hydraulic brakes (friction brakes) are generated as needed.

Japanese Unexamined Patent Publication No. 5-240075

A constant-speed traveling / inter-vehicle distance control device (ACC: Adaptive Cruise Control) is known as a device that is mounted on a vehicle and automatically executes constant-speed traveling while keeping the inter-vehicle distance constant. The constant-speed driving / inter-vehicle distance control device controls the braking system of the own vehicle to automatically decelerate when it detects that the vehicle in front is approaching.

In such a constant speed traveling / inter-vehicle distance control device, an engine brake is also used from the viewpoint of suppressing heat generation of the brake pads of the friction brake and reducing the deceleration shock at the initial stage of deceleration. That is, when the required deceleration of the automatic brake is less than a predetermined value (for example, the limit value of the braking force by the engine brake), the braking force is applied by the engine brake. Then, when the required deceleration exceeds a predetermined value, the engine brake is switched to the friction brake, and deceleration is performed according to the required deceleration from the constant speed running / inter-vehicle distance control device.

However, when changing from an engine brake to a friction brake, the friction brake has a friction braking force according to the deceleration required from the constant speed running / inter-vehicle distance control device from the state where the actual deceleration (friction braking force) is zero. Will be generated suddenly. As a result, an overshoot occurs in the friction braking force.
When the friction braking force is generated by the electric brake booster, the overshoot of the friction braking force causes the brake pedal to bottom out at the pedal end even though the driver is not operating the brake pedal. A fluttering sound is generated.

In addition, some vehicles are equipped with a sideslip prevention device (vehicle behavior stabilization device) that prevents the vehicle from bulging outward or getting caught in the curve when turning a curve to support stable driving. ing. The electronic stability control controls the braking force of each wheel individually to realize stable running of the vehicle. When the frictional braking force of the constant-speed running / inter-vehicle distance control device is realized by the sideslip prevention device, the overshoot of the frictional braking force causes the operation sound of the sideslip prevention device at the initial stage of operation (actuator drive sound and brake). The sound when the liquid is sent to the hydraulic system) becomes louder.
Therefore, the commercialization of the vehicle is lowered due to the generation of these unpleasant sounds (bottoming sound and operating sound).

As a countermeasure for these, it is conceivable to provide an end rubber at the end of the pedal or the end of the cylinder for the electric brake booster. However, in this case, since it is necessary to provide an end rubber, there is a problem that the manufacturing cost of the vehicle increases.
In addition, it is conceivable to tune the electric brake booster and the electronic stability control to slow down the deceleration of the friction braking force. However, in this case, there is a problem that the braking force performance is deteriorated and tuning is difficult due to the responsiveness of the electric brake booster and the electronic stability control.

Therefore, the subject of the present invention is that when the automatic brake is used to shift from the engine brake to the friction brake, an unpleasant sound is generated without causing problems such as an increase in manufacturing cost, a decrease in braking force performance, and difficulty in tuning. Is to be able to reduce.

In the braking force control system of the present invention, an engine brake control unit that controls the generation of engine brakes in a vehicle and a brake pedal are connected, and hydraulic pressure is applied to the wheel cylinders of each wheel of the vehicle by operating an actuator. A friction brake control unit that controls an electric brake system that supplies and generates friction brakes, a deceleration detection unit that detects the actual deceleration of the vehicle, and the vehicle for keeping the required distance from the vehicle in front. An automatic brake requesting unit that automatically requests the operation of the brake without operating the brake pedal, and if the required deceleration required by the automatic braking requesting unit is less than a predetermined value, instruct the engine brake control unit to instruct the engine. A brake selection unit that generates a braking force by the brake and, when the required deceleration is equal to or more than the predetermined value, controls the friction brake control unit to generate a braking force by the friction brake by the electric brake system, and the brake. Immediately after switching from the engine brake to the friction brake in the selection unit, the required deceleration required by the automatic brake requesting unit is once brought close to the actual deceleration detected by the deceleration detecting unit, and the deceleration increases. It is provided with a required deceleration changing unit that controls to return to the required deceleration requested by the automatic brake requesting unit again during the process .

According to the present invention, when shifting from an engine brake to a friction brake by automatic braking, the generation of unpleasant noise is reduced without causing problems such as an increase in manufacturing cost, a decrease in braking force performance, and difficulty in tuning. It can be so.

It is a block diagram which shows the system structure of the braking force control system which is one Embodiment of this invention. It is a flowchart explaining the operation of the braking force control system which is one Embodiment of this invention. It is a graph explaining the operation of the braking force control system which is one Embodiment of this invention. It is a graph explaining the operation of the braking force control system which is one Embodiment of this invention. It is a graph explaining the operation of the braking force control system which is one Embodiment of this invention.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a system configuration of a braking force control system 1 according to an embodiment of the present invention. The vehicle equipped with the braking force control system 1 is equipped with an electric brake system 101. In the vehicle, wheel cylinders 103FR, 103RL, 103RR, 103FL are provided on the right front wheel 102a, the left rear wheel 102b, the right rear wheel 102c, and the left front wheel 102d, respectively. The electric brake system 101 is a device that generates frictional braking force on each of the wheels by supplying hydraulic pressure (hydraulic pressure) to the wheel cylinders 103FR, 103RL, 103RR, 103FL via a piping tube 104.

The electric brake system 101 includes a hydraulic brake device 111 and an electronic stability control device 121.
The hydraulic brake device 111 includes an electric brake booster (not shown) to which a brake pedal 112 is connected. When the driver operates the brake pedal 112, the electric brake booster assists the driver in operating the brake pedal 112 by driving an actuator (motor, etc.) and uses a cylinder (not shown) for hydraulic pressure (flood control). ) Is generated. This oil pressure is transmitted to each wheel cylinder 103FR, 103RL, 103RR, 103FL via the piping tube 104, and a friction braking force is generated in each of the wheels.

The electronic stability control system 121 is a device for preventing the vehicle from bulging outward or getting caught in the curve when the vehicle turns a curve, and supports stable running, for example, ABS (Anti). -The function of the lock Brake System) is also executed by the electronic stability control 121. The electronic stability control 121 individually transmits hydraulic pressure (hydraulic pressure) to each wheel cylinder 103FR, 103RL, 103RR, 103FL via a piping tube 104 by driving a motor and various solenoid valves (none of which are shown). Braking force can be generated individually for each wheel.

The engine 131 is an engine that is a drive source for a vehicle. The vehicle equipped with the braking force control system 1 may be a hybrid vehicle.
The connection of each electronic component according to the diagram shown in FIG. 1 includes a portion connected by communication using CAN (Controller Area Network) and a portion directly connected.
The braking force control system 1 is mainly composed of a constant-speed traveling / inter-vehicle distance control unit 11, a brake control unit 21, and an engine control unit 31. The brake control unit 21 and the engine control unit 31 are connected to the constant speed traveling / inter-vehicle distance control unit 11.

The brake control unit 21 is connected to the electric brake system 101 and serves as a friction brake control unit that controls the electric brake system 101. That is, the brake control unit 21 is composed of one or a plurality of ECUs (Electronic Control Units), controls the hydraulic brake device 111 according to the operation of the brake pedal 112, and automatically controls the sideslip prevention device 121. Also do. A brake pedal stroke sensor 22 that detects the moving stroke and moving speed of the brake pedal 112 is connected to the brake control unit 21. The brake control unit 21 controls the actuator of the electric brake booster of the hydraulic brake device 111 by detecting the moving stroke of the brake pedal 112 by the brake pedal stroke sensor 22.

The engine control unit 31 is composed of one or a plurality of ECUs including, for example, an FI (Fuel Injection) -ECU, is connected to the engine 131, and executes various controls of the engine 131. In particular, the engine control unit 31 is an engine brake control unit that controls the generation of engine braking.

A millimeter-wave radar 17, a monocular camera 18, an engine control unit 31, and a vehicle speed sensor 19 are connected to the constant-speed traveling / inter-vehicle distance control unit 11. The constant-speed traveling / inter-vehicle distance control unit 11 controls the vehicle to automatically accelerate and decelerate within a preset vehicle speed, and can follow the vehicle while maintaining an appropriate inter-vehicle distance from the preceding vehicle. And. The constant speed traveling / inter-vehicle distance control unit 11 is composed of one or a plurality of ECUs. The constant speed traveling / inter-vehicle distance control unit 11 realizes the functions of the automatic brake request unit 12, the brake selection unit 13, the required deceleration change unit 14, the emergency brake request unit 15, and the difference calculation unit 16. Details of the functions of each of these parts will be described later.

A millimeter-wave radar 17 and a monocular camera 18 for detecting the distance and positional relationship with the vehicle in front and the like are connected to the constant-speed traveling / inter-vehicle distance control unit 11. In addition, an infrared laser, a stereo camera, etc. A method using a sensor or an image sensor may be used. Further, the vehicle speed sensor 19 connected to the constant speed traveling / inter-vehicle distance control unit 11 serves as a deceleration detection unit for detecting the deceleration of the vehicle.

Next, the operation of the electric brake system 101 will be described. FIG. 2 is a flowchart illustrating the operation of the electric brake system 101. 3 to 5 are graphs illustrating the operation of the electric brake system 101.

The constant-speed traveling / inter-vehicle distance control unit 11 controls the vehicle to perform constant-speed traveling while keeping the inter-vehicle distance from the preceding vehicle constant. Therefore, as long as the distance between the vehicle and the vehicle in front does not change, the engine 131 is controlled via the engine control unit 31 so that the vehicle travels at a predetermined constant speed. In the case of a hybrid vehicle, the motor / generator, which is the drive source of the vehicle, may be controlled to execute constant speed driving.

Here, it will be described with reference to FIGS. 3 to 5. 3 and 5 are graphs in which the horizontal axis is “time” and the vertical axis is “friction brake request” and “deceleration”. Here, the "friction brake request" indicates whether or not the brake selection unit 13 has requested the generation of the friction brake. When the friction brake request is 0.0, it indicates OFF (no friction brake request), and when 1.0, it indicates ON (with friction brake request). In addition, "deceleration" indicates the deceleration of the vehicle (negative speed when decelerating the vehicle), and 0.0 indicates that the deceleration of the vehicle is zero. The lower the value, the greater the deceleration of the vehicle.

The figures shown in FIGS. 3 and 5 are the friction brake requirement 51, the required deceleration 52, the actual deceleration 53, and the engine brake upper limit deceleration 54. The friction brake request 51 indicates ON / OFF of the friction brake request. The required deceleration 52 indicates the degree of deceleration of the vehicle required by the automatic brake requesting unit 12. The actual deceleration 53 is the deceleration of the actual vehicle. This can be obtained from the vehicle speed detected by the vehicle speed sensor 19. The engine brake upper limit deceleration 54 is a limit value (upper limit value) for deceleration by the engine brake described above. Further, FIG. 4 is an enlarged view of the broken line region 55 in FIG.

First, as shown in FIG. 3, there is no demand for automatic braking in the region 61 where the required deceleration 52 is flat and shows 0.0, and the vehicle is traveling at a predetermined constant speed. After that, when the inter-vehicle distance between the vehicle in front and the own vehicle becomes short, the automatic brake requesting unit 12 makes an automatic braking request (Yes in S1) as shown in FIG. 2 so as to recover the inter-vehicle distance. The deceleration of the vehicle at this time is also requested by the automatic brake requesting unit 12 (required deceleration 52).

That is, as shown in FIG. 4, when the required deceleration 52 is at time 62, the automatic braking request is made from the automatic brake requesting unit 12, and the required deceleration 52 gradually increases from 0.0. As a result, braking is initially started by the engine brake (S2). That is, based on the automatic brake request and the required deceleration output by the automatic brake request unit 12, the brake selection unit 13 controls the engine 131 via the engine control unit 31 to apply the engine brake. In this case, in order to realize the deceleration of the vehicle according to the required deceleration 52 by the engine brake, it is possible to control the shift to a predetermined stage.

When the required deceleration 52 required by the automatic brake requesting unit 12 increases as it is, the required deceleration 52 reaches the engine brake upper limit deceleration 54 (or is a value of a predetermined required deceleration 52 before that. May be). The value at that time is the first required deceleration 63. When the required deceleration 52 is larger than the first required deceleration 63, the brake selection unit 13 needs to change the braking to a friction brake. That is, the first required deceleration 63 is the required deceleration 52 immediately before the braking shifts to the friction brake.

As mentioned above, there is a limit value for decelerating the vehicle by engine braking. When the required deceleration of the automatic brake requesting unit 12 reaches the limit value of the engine braking upper limit deceleration 54 (or when it reaches a predetermined value close to the value), the brake selection unit 13 performs the required deceleration 52. The means of realizing the above is switched from the engine brake to the friction brake (Yes or less in S3). That is, the brake selection unit 13 switches the friction brake request from the OFF state (0.0) to the ON state (1.0). The friction brake in this case may be generated by the operation of the hydraulic braking device 111, or may be generated by the operation of the sideslip prevention device 121. When the required deceleration of the automatic brake requesting unit 12 has not reached the limit value or the like, the process returns to S2. Even if the means for realizing the required deceleration 52 is switched from the engine brake to the friction brake, the engine brake may be continuously operated.

Even in the case of Yes in S3, the transition control from the engine brake to the friction brake is not uniform. That is, in the case of Yes in S3, it is determined whether or not the emergency brake request is made by the emergency brake request unit 15 (S4). That is, when it is urgently necessary to avoid a collision with an obstacle such as a vehicle in front of the vehicle, the emergency brake requesting unit 15 automatically requests the operation of the brake without operating the brake pedal 112. When the emergency brake request is made from the emergency brake request unit 15 (Yes in S4), the process proceeds to S9. If not (No in S4), the process proceeds to S5. The emergency brake requesting unit 15 may be realized by a control unit (ECU) of a system different from the constant speed traveling / inter-vehicle distance control unit 11.

In the case of No in S4, the difference calculation unit 16 calculates the difference between the first required deceleration 63 and the actual deceleration 53 at that time (S5). Then, the required deceleration changing unit 14 determines whether or not the calculated difference is less than a predetermined value (S6). Then, when the difference is less than the predetermined value (Yes in S6), the process proceeds to S9. If not (No in S6), the process proceeds to S7.

As shown in FIGS. 2 to 4, in S7, the required deceleration changing unit 14 reduces the required deceleration 52 from the first required deceleration 63 to the second required deceleration 64 at a predetermined reduction rate. Braking is performed by friction braking. In this case, as shown in FIGS. 3 and 4, the required deceleration changing unit 14 sets the second required deceleration 64 closer to the actual deceleration 53 or has substantially the same value. Further, as shown in FIG. 4, the inclination of the required deceleration 52a having a predetermined reduction rate from the first required deceleration 63 to the second required deceleration 64 is the inclination of the line 71.
Further, in this case, as shown in FIG. 4, the required deceleration changing unit 14 sets the second required deceleration 64 from the intermediate deceleration 72, which is an intermediate value between the first required deceleration 63 and the actual deceleration 53. Is also set to a low value. That is, a gentle friction brake is used.

As shown in FIGS. 2 and 4, when the required deceleration changing unit 14 changes the required deceleration 52 to the second required deceleration 64, the required deceleration requesting unit 12 immediately requests the required deceleration by the original automatic braking requesting unit 12. Return to speed 52 (S8). In this case, the rate of increase when the required deceleration is increased from the second required deceleration 64 toward the required deceleration 52 required by the automatic brake requesting unit 12 is set as a predetermined increase rate. The slope of the required deceleration 52b, which is the predetermined rate of increase in this case, is the slope of the line 73 in FIG. The portion shown by the broken line of the required deceleration 52 in FIG. 4 is the required deceleration output by the original automatic brake requesting unit 12 when the required deceleration changing unit 14 does not change the required deceleration 52. 52 is shown.
Then, the required deceleration changing unit 14 is set so that the absolute value of the increase rate indicated by the inclination of the line 73 is smaller than the absolute value of the reduction rate indicated by the inclination of the line 71.

As described above, the required deceleration 52 is once reduced to the second required deceleration 64 immediately after switching from the engine brake to the friction brake, and then returns to the original required deceleration 52 again. As a result, the required deceleration 52 is momentarily controlled to be brought close to the actual deceleration 53 or to be set to substantially the same value and returned to the required deceleration 52 required by the automatic brake requesting unit 12.
As described above, after the processes of S7 and S8 are executed, the friction brake is used to brake according to the required deceleration 52 required by the automatic brake requesting unit 12 (S9).

Further, in the case of Yes of S4 and Yes of S6 described above, the processes of S7 and S8 described above are omitted, and the process of S9 is executed. The graph corresponding to FIG. 3 in this case is FIG. In this case, as shown in FIG. 5, when the engine brake is switched to the friction brake (time point 81), the actual deceleration 53 tends to overshoot.

According to the braking force control system 1 of the present embodiment described above, the required deceleration 52 is brought close to the actual deceleration 53 or set to substantially the same value immediately after switching from the engine brake to the friction brake (second required deceleration). 64). Then, the control for returning to the required deceleration 52 requested by the automatic brake requesting unit 12 is performed again. Such a series of treatments is instantaneously performed in a short time (for example, around 0.1s to 0.2s).
Further, as shown in FIG. 4, the required deceleration changing unit 14 sets the second required deceleration 64 to a value lower than the intermediate deceleration 72, which is an intermediate value between the first required deceleration 63 and the actual deceleration 53. Set.
Further, as described above, the second required deceleration 64 may be substantially the same as the actual deceleration 53.

As a result, by reducing the deceleration when switching from the engine brake to the friction brake, the overshoot of the actual deceleration is suppressed and the bottoming sound of the brake pedal 112 in the hydraulic brake device 111 or the sideslip prevention device 121. It is possible to reduce the generation of operating noise. In fact, in the example of FIG. 5, the actual deceleration 53 suddenly drops at a time near the first deceleration 63, and the actual deceleration 53 tends to overshoot. That is, the bottom of the brake pedal 112 may be bottomed out. However, in the example of FIG. 3, the actual deceleration 53 has a gentle downward slope at the time near the first deceleration 63 and the second deceleration 64, and no overshoot occurs. Therefore, it is possible to suppress an increase in manufacturing cost due to the addition of end rubber and a decrease in responsiveness of the friction brake. Therefore, the commercial value of the vehicle can be improved. Further, if the brake pedal 112 is automatically depressed greatly and bottomed out when the driver is not operating the brake pedal 112, the driver feels uncomfortable. In the example of FIG. 3, such a situation occurs. Absent.

In addition, the required deceleration is increased from the second required deceleration 64 toward the required deceleration 52 by the automatic brake requesting unit 12. As a result, after the required deceleration 52 is reduced to the second required deceleration 64, the actual deceleration 53 can be made to follow the original required deceleration 52 by the automatic brake requesting unit 12.

Further, the required deceleration changing unit 14 is set so that the absolute value of the increase rate indicated by the inclination of the line 73 is smaller than the absolute value of the reduction rate indicated by the inclination of the line 71. As a result, by increasing the reduction rate of the required deceleration 52a, the deceleration can be quickly reduced when switching from the engine brake to the friction brake. In addition, the overshoot of the actual deceleration 53 can be suppressed at an early timing. Further, by setting the increase rate of the required deceleration 52b to be small, the increase rate of the actual deceleration 53 after the required deceleration 52b is reduced is set to a level at which the actual deceleration 53 overshoot does not occur (bottoming out). It can be suppressed to a level that does not occur).

Further, when there is a request for emergency braking (Yes in S4), the processing of S7 and S8 is prohibited. As a result, when the emergency automatic braking is activated, the generation of braking force (braking property) can be enhanced.

Moreover, when the difference between the first required deceleration 63 and the actual deceleration 53 at that time is less than a predetermined value (Yes in S6), the processing of S7 and S8 is prohibited. As a result, the difference between the first required deceleration 63 and the actual deceleration 53 does not generate the operating noise of the hydraulic brake device 111 or the sideslip prevention device 121, or only the noise that the occupants do not care about. In the case of the difference between, the engine brake can be switched to the friction brake at an early stage without performing the processes of S7 and S8.

1 Braking force control system 12 Automatic brake request unit 13 Brake selection unit 14 Required deceleration change unit 15 Emergency brake request unit 16 Difference calculation unit 21 Brake control unit (collision brake control unit)
31 Engine control unit (engine brake control unit)
22 Brake pedal stroke sensor (deceleration detector)
52 Required deceleration 53 Actual deceleration 54 Engine brake upper limit deceleration (predetermined value)
63 1st required deceleration 64 2nd required deceleration 72 Intermediate deceleration 101 Electric brake system 103FR, 103RL, 103RR, 103FL Wheel cylinder 112 Brake pedal

Claims (7)

The engine brake control unit that controls the generation of engine braking in the vehicle,
A friction brake control unit that controls an electric brake system that is connected to a brake pedal and supplies hydraulic pressure to the wheel cylinders of each wheel of the vehicle by the operation of an actuator to generate friction brakes.
A deceleration detector that detects the actual deceleration of the vehicle,
An automatic brake requesting unit that automatically requests the operation of the brake without operating the brake pedal in order for the vehicle to keep the required distance from the vehicle in front.
When the required deceleration required by the automatic brake requesting unit is less than a predetermined value, the engine brake control unit is instructed to generate a braking force by the engine brake, and when the required deceleration is equal to or more than the predetermined value. Controls the friction brake control unit and generates a braking force by the friction brake by the electric brake system, and a brake selection unit.
Immediately after switching from the engine brake to the friction brake in the brake selection unit, the required deceleration required by the automatic brake requesting unit is once brought close to the actual deceleration detected by the deceleration detecting unit to reduce the deceleration. A braking force control system including a required deceleration changing unit that controls to return to the required deceleration required by the automatic braking request unit again while the speed is increasing . When the required deceleration immediately before the brake selection unit switches from the engine brake to the friction brake is set as the first required deceleration, and the required deceleration immediately after the switching is set as the second required deceleration.
Claim 1 is characterized in that the required deceleration changing unit sets the second required deceleration to a deceleration lower than the intermediate deceleration between the first required deceleration and the actual deceleration. The braking force control system described in. The braking force control system according to claim 2, wherein the required deceleration changing unit makes the second required deceleration about the same as the actual deceleration. The required deceleration changing unit determines the automatic braking request from the absolute value of the reduction rate when the required deceleration is reduced from the first required deceleration to the second required deceleration and the second required deceleration. The braking force control system according to claim 3, wherein the absolute value of the rate of increase when the required deceleration is increased is made different from the required deceleration required by the unit. The braking force control system according to claim 4, wherein the required deceleration changing unit makes the increase rate smaller than the reduction rate. It is provided with an emergency brake requesting unit that automatically requests the operation of the brake without operating the brake pedal in order to avoid a collision with an obstacle in front of the vehicle.
When the emergency brake requesting unit requests the operation of the brake, the required deceleration changing unit reduces the required deceleration requested by the automatic braking requesting unit from the first required deceleration to the second required deceleration. The braking force control system according to any one of claims 2 to 5, wherein the speed is prohibited. The engine brake control unit that controls the generation of engine braking in the vehicle,
A friction brake control unit that controls an electric brake system that is connected to a brake pedal and supplies hydraulic pressure to the wheel cylinders of each wheel of the vehicle by the operation of an actuator to generate friction brakes.
A deceleration detector that detects the actual deceleration of the vehicle,
An automatic brake requesting unit that automatically requests the operation of the brake without operating the brake pedal in order for the vehicle to keep the required distance from the vehicle in front.
When the required deceleration required by the automatic brake requesting unit is less than a predetermined value, the engine brake control unit is instructed to generate a braking force by the engine brake, and when the required deceleration is equal to or more than the predetermined value. Controls the friction brake control unit and generates a braking force by the friction brake by the electric brake system, and a brake selection unit.
Immediately after switching from the engine brake to the friction brake in the brake selection unit, the required deceleration required by the automatic brake requesting unit is once brought close to the actual deceleration detected by the deceleration detecting unit, and the automatic braking is performed again. It is provided with a required deceleration changing unit that controls to return to the required deceleration required by the requesting unit .
When the required deceleration immediately before the brake selection unit switches from the engine brake to the friction brake is set as the first required deceleration, and the required deceleration immediately after the switching is set as the second required deceleration.
The required deceleration changing unit sets the second required deceleration to a deceleration lower than the intermediate deceleration between the first required deceleration and the actual deceleration.
A difference calculation unit for calculating the difference between the first required deceleration and the actual deceleration is provided.
When the difference calculated by the difference calculation unit is less than a predetermined value, the required deceleration changing unit changes the required deceleration requested by the automatic brake requesting unit from the first required deceleration to the second required deceleration. Braking force control system characterized by prohibiting the use of.

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