JP2007030581A - Vehicle brake device, and overrun preventing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve brake responsiveness of a vehicle after overrunning onto a step. <P>SOLUTION: This vehicle brake device for braking a vehicle is provided with a hydraulic actuator 100 to provide braking force to wheels of the vehicle, and an ECU 200. The ECU 200 includes an overrun judging part 74 to judge if the vehicle has overrun onto a step, and an actuator control part 84 to actuate the hydraulic actuator 100 to such a degree that braking force is not substantially provided to the wheels when the overrun judging part 74 judges that the vehicle has overrun onto the step. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a vehicle braking device for braking a vehicle and an overrun prevention method for preventing overrun after the vehicle has climbed a step.

Conventionally, as a technique for stabilizing the behavior of a vehicle when the vehicle climbs a step, the vehicle speed is substantially zero and the engine speed exceeds the threshold value even though the accelerator operation is performed. In addition, a technique for gently increasing the upper limit value of the throttle opening is known (see, for example, Patent Document 1). In this technique, even when the driver depresses the accelerator pedal more rapidly than necessary in order to climb a step, the upper limit value of the throttle opening increases gently, so that the throttle does not open suddenly. Further, the throttle does not open at an opening degree equal to or higher than the upper limit value. As a result, a sudden change in the behavior of the vehicle after climbing the step caused by the driver depressing the accelerator more than necessary is suppressed.
As a technology to alleviate the impact applied to the vehicle when riding over small steps such as road joints during normal driving, the vehicle body reacts by reversing the braking force once it is generated and released immediately before the step. A technique is known in which nose-up is made to overcome a step (see, for example, Patent Document 2). Further, in Patent Document 3, before the driver operates the brake during normal driving, the brake cylinder hydraulic pressure is increased within a range where no braking force is generated. And a technique for suppressing the delay in braking effectiveness is disclosed.
JP-A-8-200111 Japanese Patent Laid-Open No. 2003-72535 JP 2003-252189 A

  As mentioned above, when the vehicle rides on a relatively large step, such as when parked, the driver steps on the accelerator against the increase in running resistance to get over the step, but after the vehicle gets on the step, When stopping, it is necessary to perform the brake operation immediately after the accelerator operation. However, if the driver's braking operation is delayed at this time, the vehicle may not be stopped at a desired position.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to improve the braking response after the vehicle has climbed a step.

One aspect of the present invention relates to a vehicle braking device. The vehicle braking device is a vehicle braking device for braking the vehicle, and includes a braking force applying unit that applies a braking force to the wheels of the vehicle, a determination unit that determines whether or not the vehicle is riding on a step, And a control unit that operates the braking force applying unit to such an extent that the braking force is not substantially applied to the wheel when the determining unit determines that the vehicle is riding on a step.
The control means of the vehicle braking device activates the braking force applying means to such an extent that the braking force is not substantially generated when it is determined by the determination means that the vehicle is riding on a step. In this way, when the vehicle rides on the step, the braking force applying means is slightly operated in preparation for the driver's brake operation after stepping on the step, so that the driver can perform the brake operation after stepping on the step. Since the braking response can be improved, the vehicle can be stopped quickly.

  The determination means is configured to determine whether the vehicle speed corresponding to the request of at least one of the driver and the driving support system is satisfied even though the predetermined output request for the driving source of the vehicle is made by at least one of the driver and the driving support system. When it is not obtained, it may be determined that the vehicle is on a step. According to this aspect, by monitoring the output of the drive source of the vehicle and the vehicle speed, it can be determined easily and accurately whether or not the vehicle is riding on a step.

  The control means generates a command for operating the braking force applying means to such an extent that the braking force is not substantially applied to the wheels when the determining means determines that the vehicle is on the step, and the vehicle After the vehicle rides on, the command may be canceled when the vehicle speed falls below a predetermined value. According to this aspect, even if the driver activates the braking force applying means after the vehicle has stepped on the step, the above command is not released until the vehicle speed is sufficiently lowered, so that a good braking response is achieved. Can be maintained.

Another embodiment of the present invention relates to a method for preventing overrun. This overrun prevention method is an overrun prevention method for preventing an overrun after the vehicle has climbed a step using a braking force applying means for applying a braking force to the wheels of the vehicle. And a step of operating the braking force applying means to such an extent that the braking force is not substantially applied to the wheels when it is determined that the vehicle is on a step.
In this overrun prevention method, when the vehicle is riding on a step, the braking force applying means is operated to such an extent that substantially no braking force is generated in preparation for the operation of the braking force applying means by the driver after climbing the step. . As a result, it is possible to improve the braking response at the time of the brake operation by the driver after climbing the step, so that it is possible to prevent the vehicle overrun after climbing the step.

  According to the vehicle braking device and the overrun prevention method of the present invention, it is possible to improve the braking response after the vehicle has climbed a step.

  FIG. 1 is a system diagram showing a vehicle braking device in the present embodiment. The vehicle braking device 10 shown in the figure constitutes an electronically controlled brake system (ECB) for a vehicle, and independently and optimally brakes the four wheels of the vehicle according to the operation of the brake pedal 12 by the driver. It is to set. The brake pedal 12 is connected to a master cylinder 14 that sends out brake oil as working fluid (working fluid) in response to a depression operation by a driver. The brake pedal 12 is provided with a stroke sensor 46 for detecting the depression stroke. Further, a reservoir tank 26 is connected to the master cylinder 14, and a reaction force corresponding to the operating force of the brake pedal 12 by the driver is created at one output port of the master cylinder 14 via the on-off valve 23. A stroke simulator 24 is connected. The on-off valve 23 is a normally closed electromagnetic valve that is closed when not energized and is switched to an open state when the operation of the brake pedal 12 by the driver is detected.

  A brake hydraulic pressure control pipe 16 for the right front wheel is connected to one output port of the master cylinder 14, and the brake hydraulic pressure control pipe 16 applies a braking force to the right front wheel (not shown). It is connected to the cylinder 20FR. A brake hydraulic pressure control pipe 18 for the left front wheel is connected to the other output port of the master cylinder 14, and the brake hydraulic pressure control pipe 18 is for the left front wheel that applies a braking force to the left front wheel (not shown). Connected to the wheel cylinder 20FL. A right electromagnetic on-off valve 22FR is provided in the middle of the brake hydraulic control pipe 16 for the right front wheel, and a left electromagnetic on-off valve 22FL is provided in the middle of the brake hydraulic control pipe 18 for the left front wheel. The right solenoid on-off valve 22FR and the left solenoid on-off valve 22FL are both normally open solenoid valves that are open when not energized and are switched to the closed state when the operation of the brake pedal 12 by the driver is detected. is there.

  A right master pressure sensor 48FR for detecting the master cylinder pressure on the right front wheel side is provided in the middle of the brake hydraulic control pipe 16 for the right front wheel, and in the middle of the brake hydraulic control pipe 18 for the left front wheel. A left master pressure sensor 48FL for measuring the master cylinder pressure on the left front wheel side is provided. In the vehicle braking device 10, when the brake pedal 12 is depressed by a driver, the stroke sensor 46 detects the depression operation amount. The master cylinder detected by the right master pressure sensor 48FR and the left master pressure sensor 48FL. The depressing operation force of the brake pedal 12 can also be obtained from the pressure. As described above, it is preferable from the viewpoint of fail-safe that the master cylinder pressure is monitored by the two pressure sensors 48FR and 48FL on the assumption of the failure of the stroke sensor 46.

  On the other hand, one end of a hydraulic supply / discharge pipe 28 is connected to the reservoir tank 26, and a suction port of an oil pump 34 driven by a motor 32 is connected to the other end of the hydraulic supply / discharge pipe 28. . The discharge port of the oil pump 34 is connected to a high pressure pipe 30, and an accumulator 50 and a relief valve 53 are connected to the high pressure pipe 30. In the present embodiment, a reciprocating pump including two or more pistons (not shown) that are reciprocally moved by the motor 32 is employed as the oil pump 34. Further, as the accumulator 50, an accumulator 50 that converts the pressure energy of the brake oil into the pressure energy of an enclosed gas such as nitrogen is stored.

  The accumulator 50 stores brake oil whose pressure has been increased to about 14 to 22 MPa by the oil pump 34, for example. Further, the valve outlet of the relief valve 53 is connected to the hydraulic supply / discharge pipe 28. When the pressure of the brake oil in the accumulator 50 increases abnormally to about 25 MPa, for example, the relief valve 53 is opened and the high-pressure brake is opened. The oil is returned to the hydraulic supply / discharge pipe 28. Further, the high-pressure pipe 30 is provided with an accumulator pressure sensor 51 that detects the outlet pressure of the accumulator 50, that is, the pressure of the brake oil in the accumulator 50.

  The high pressure pipe 30 is connected to the right front wheel wheel cylinder 20FR, the left front wheel wheel cylinder 20FL, the right rear wheel wheel cylinder 20RR, and the left rear wheel wheel cylinder 20RL via the pressure increasing valves 40FR, 40FL, 40RR, 40RL. It is connected to the. Hereinafter, the wheel cylinders 20FR to 20RL will be collectively referred to as “wheel cylinders 20”, and the pressure increase valves 40FR to 40RL will be appropriately collectively referred to as “pressure increase valves 40”. Each of the pressure increasing valves 40 is a normally closed electromagnetic flow control valve (linear valve) that is closed when not energized and is used to increase the pressure of the wheel cylinder 20 as necessary. A disc brake unit is provided for each wheel of the vehicle (not shown), and each disc brake unit generates a braking force by pressing the brake pad against the disc by the action of the wheel cylinder 20.

  The right front wheel wheel cylinder 20FR and the left front wheel wheel cylinder 20FL are connected to the hydraulic supply / discharge pipe 28 via pressure reducing valves 42FR or 42FL, respectively. The pressure reducing valves 42FR and 42FL are normally closed electromagnetic flow control valves (linear valves) used for pressure reduction of the wheel cylinders 20FR and 20FL as necessary. On the other hand, the wheel cylinder 20RR for the right rear wheel and the wheel cylinder 20RL for the left rear wheel are connected to the hydraulic supply / discharge pipe 28 via a pressure reducing valve 42RR or 42RL which is a normally open electromagnetic flow control valve. . Hereinafter, the pressure reducing valves 42FR to 42RL are collectively referred to as “pressure reducing valve 42” as appropriate. Further, in the vicinity of the wheel cylinders 20FR to 20RL of the right front wheel, the left front wheel, the right rear wheel, and the left rear wheel, cylinder pressure sensors 44FR and 44FL for detecting a wheel cylinder pressure, which is a brake oil pressure in the corresponding wheel cylinder 20, respectively. , 44RR and 44RL. Hereinafter, the cylinder pressure sensors 44FR to 20RL will be collectively referred to as “cylinder pressure sensor 44” as appropriate.

  The right electromagnetic on-off valve 22FR and the left electromagnetic on-off valve 22FL, the pressure increasing valves 40FR to 40RL, the pressure reducing valves 42FR to 42RL, the oil pump 34, the accumulator 50, and the like constitute the hydraulic actuator 100 of the vehicle braking device 10. The hydraulic actuator 100 is controlled by an electronic control unit (hereinafter referred to as “ECU”) 200. The ECU 200 includes a CPU that executes various arithmetic processes, a ROM that stores various control programs, a RAM that is used as a work area for data storage and program execution, an input / output interface, a memory, and the like.

  The ECU 200 is electrically connected to the electromagnetic on-off valves 22FR and 22FL, the on-off valve 23, the pressure increasing valves 40FR to 40RL, the pressure reducing valves 42FR to 42RL, the motor 32, and the like. The electromagnetic on-off valves 22FR and 22FL, the on-off valve 23, the pressure increasing valves 40FR to 40RL, and the pressure reducing valves 42FR to 42RL are respectively controlled by an actuator control unit 84 (see FIG. 2) constructed in the ECU 200. On the other hand, the motor 32 for driving the oil pump 34 is controlled by a motor control unit (not shown) built in the ECU 200.

  Further, the ECU 200 receives signals indicating the wheel cylinder pressure in the wheel cylinders 20FR to 20RL from the cylinder pressure sensors 44FR to 44RL. Further, the ECU 200 is given a signal indicating the depression stroke of the brake pedal 12 from the stroke sensor 46, and is given a signal indicating the master cylinder pressure from the right master pressure sensor 48FR and the left master pressure sensor 48FL. In addition, the ECU 200 is supplied with a signal indicating the pressure of the brake oil in the accumulator 50 (hereinafter referred to as “accumulator pressure” as appropriate) from the accumulator pressure sensor 51. Further, the ECU 200 is connected to the travel support ECU. The travel support ECU 300 is connected to a navigation system, a radar unit, a backlight camera, and the like, and performs parking support control and vehicle follow-up control based on information acquired by these information acquisition means. In other words, the driving assistance ECU 300 derives and derives the output necessary for parking the vehicle or following the vehicle when a driving assistance request such as a parking assistance request or a following driving request is made by the driver. An output or the like is output to the ECU 200.

  In the vehicle braking device 10 configured as described above, the ECU 200 calculates the target deceleration of the vehicle from the depression stroke of the brake pedal 12 and the master cylinder pressure, and the target value of each wheel according to the calculated target deceleration. Is required. Then, the actuator control unit 84 determines the control current value to the pressure increasing valve 40 and the pressure reducing valve 42 so that the wheel cylinder pressure of each wheel becomes the target value, and the pressure increasing valve 40 and the pressure reducing valve 42 are feedback-controlled. Further, when the brake pedal 12 is depressed and the brake oil in the accumulator 50 is consumed, the ECU 200 causes the motor according to the detected value of the accumulator pressure sensor 51 so that the pressure of the accumulator 50 is always within a desired range. 32 is actuated to drive the oil pump 34. As a result, the oil pump 34 draws in brake oil from the reservoir tank 26 via the hydraulic supply / discharge pipe 28, boosts the brake oil, and supplies it to the accumulator 50.

  Further, in the present embodiment, when the vehicle climbs up the step, the hydraulic actuator 100 is controlled by the ECU 200 so that the wheel cylinder pressure increases to such an extent that a braking force is not substantially generated. Hereinafter, this control is referred to as “preliminary braking control”. The preliminary braking control is performed regardless of the driver's brake operation.

  FIG. 2 is a control block diagram for explaining the preliminary braking control executed by the ECU 200. As shown in the figure, the ECU 200 is connected to a stroke sensor 46, a throttle opening sensor 60, and a vehicle speed sensor 62. As described above, the stroke sensor 46 detects the amount by which the driver depresses the brake pedal 12 and outputs it to the ECU 200. The throttle opening sensor 60 detects the opening of a throttle (not shown) while the vehicle is running and outputs it to the ECU 200. The vehicle speed sensor 62 detects the vehicle speed of the traveling vehicle and outputs it to the ECU 200.

  Further, ECU 200 includes a torque calculation unit 70, a climbing determination reference storage unit 72, a climbing determination unit 74, a brake determination unit 78, a preliminary braking flag setting unit 80, and an actuator control unit 84. The torque calculation unit 70 generates a vehicle engine (not shown) from a throttle opening detected by the throttle opening sensor 60 using a predetermined map or the like stored in the boarding determination reference storage unit 72. The torque to be calculated is calculated. In addition to this map, the boarding determination criterion storage unit 72 stores a plurality of types of threshold values used for determination described later. The torque generated by the engine may be calculated from the engine intake air amount, the intake pressure, and the engine fuel injection amount using a map or a mathematical formula, or may be calculated from a driving force transmission system or a torque sensor provided in the engine, tire, etc. The output may be measured.

The boarding determination unit 74 calculates the amount of change in torque using the torque calculated by the torque calculation unit 70. Then, based on the calculated change amount (increase amount) and the vehicle speed detected by the vehicle speed sensor 62, it is determined whether or not the vehicle has climbed the step. When the driving support request is made by the driver, the boarding determination unit 74 determines the vehicle speed according to the vehicle speed detected by the vehicle speed sensor 62 and the request from the driving support ECU 300 (for example, a request to keep the output constant). Based on the above, it is determined whether or not the vehicle has climbed the step.
In the present embodiment, the amount of change in torque is used to determine whether or not to climb a step, but the amount of change in engine output (horsepower) may be used. In the present embodiment, the climbing determination unit 74 uses a torque change amount (increase amount) to determine whether or not to climb a step. Further, an acceleration sensor (front and rear G sensor) is provided in the vehicle, and the acceleration sensor It may be determined whether or not the vehicle is riding on a step based on the detected acceleration. This also makes it possible to accurately determine whether or not the step has been climbed. Also, based on a comparison between the acceleration calculated from the change in wheel speed and the expected acceleration calculated from the torque or horsepower generated by the vehicle and the vehicle weight, it is determined whether or not the vehicle is riding on a step. Also good.

  The brake determination unit 78 determines whether or not a brake operation is performed by the driver based on the brake pedal depression amount detected by the stroke sensor 46. The determination as to whether or not the brake is being operated may be made with reference to the on / off state of the brake lamp switch. Alternatively, a brake pedal depression force sensor may be provided in the vehicle, and the determination may be made based on whether or not the output of the depression force sensor exceeds a predetermined threshold value. Furthermore, it may be determined by any combination of output results of the stroke sensor, the brake lamp switch, and the pedal force sensor. Since these sensors are generally provided in a vehicle, it is possible to easily determine whether or not to climb a step and perform preliminary braking control without preparing a new sensor.

  The preliminary braking flag setting unit 80 sets a preliminary braking flag for allowing execution of the preliminary braking control based on the determination result of whether or not the brake operation has been performed and the determination result of whether or not the vehicle is riding on a step. . Further, the preliminary braking flag setting unit 80 determines whether or not the vehicle speed is a value that can be quickly stopped at a desired position by a driver's braking operation, and releases the preliminary braking flag according to the determination result. Note that the preliminary braking flag setting unit 80 may make this determination based on the engine output, or may make the determination based on the wheel speed. The actuator control unit 84 executes the preliminary braking control for all the wheels of the vehicle when the preliminary braking flag is set, and stops the preliminary braking control when the preliminary braking flag is released. Note that the preliminary braking control may be executed only on specific wheels in accordance with the characteristics of the vehicle.

FIG. 3 is a flowchart showing a process of setting and releasing the preliminary braking flag by the ECU 200. The routine described below is executed at regular time intervals during vehicle operation, for example, at intervals of 20 to 50 msec.
At the execution timing of this routine, the brake determination unit 78 compares the brake depression amount detected by the stroke sensor 46 with a predetermined threshold value related to the brake pedal depression operation amount stored in the riding determination criterion storage unit 72. Then, it is determined whether or not a brake operation is not performed by the driver (S10). Here, when the depression amount of the brake pedal is larger than the threshold value, it is determined that the brake operation is performed (N in S10), and when the brake depression amount is equal to or less than the predetermined threshold value, it is determined that the brake operation is not performed. (Y of S10).

  If it is determined that the brake operation is not performed (Y in S10), the boarding determination unit 74 determines whether or not the vehicle is riding on a step (S12). Specifically, when the driving support request is not made by the driver, the climbing determination unit 74 is a predetermined amount related to the calculated torque variation and the torque variation stored in the climbing criterion storage unit 72. Compare with the threshold. When the calculated amount of change in torque is larger than the threshold value, the climbing determination unit 74 is a predetermined threshold value related to the vehicle speed detected by the vehicle speed sensor 62 and the vehicle speed stored in the climbing determination criterion storage unit 72. And compare. As a result of the comparison, when the detected vehicle speed is equal to or lower than the threshold value, the riding-up determination unit 74 determines that the vehicle is riding on the step. When the driving support request is made by the driver, the boarding determination unit 74 compares the vehicle speed detected by the vehicle speed sensor 62 with the vehicle speed according to the request from the driving support ECU 300. As a result of this comparison, when the detected vehicle speed is smaller than the vehicle speed according to the request from the travel support ECU 300, the boarding determination unit 74 determines that the vehicle is riding on a step. As described above, in the present embodiment, when the driver requests a predetermined output for the engine that is a driving source of the vehicle, but the vehicle speed according to the driver's request is not obtained, the vehicle Is determined to be on the step. Thus, it is possible to accurately determine whether the vehicle is climbing up a step by simply monitoring the engine torque and the vehicle speed.

  If it is determined in S12 that the vehicle is riding on a step (Y in S12), the preliminary braking flag setting unit 80 sets the preliminary braking flag (S14), and the processing after S10 is executed again. . When the preliminary braking flag is set, the actuator controller 84 executes preliminary braking control. Specifically, the pressure-increasing valves 40 corresponding to all the wheels are opened for a predetermined very short time to increase the wheel cylinder pressure. As a result, the brake pads are close enough not to contact the disc. As a result, since the wheel cylinder pressure has already increased when the driver performs the brake operation after the vehicle has climbed the step, the braking responsiveness when the driver performs the brake operation after climbing the step is improved. . As the preliminary braking control, the actuator control unit 84 may control the pressure increasing valve 40 included in the hydraulic actuator 100 so that the brake pad comes into contact with the disk to the extent that a slight braking force is generated. The control target is not limited to the pressure increasing valve 40 as long as the wheel cylinder pressure can be increased to the extent that no braking force is generated.

  When the vehicle has finished climbing the level difference and the driver has not yet operated the brake, the detected brake depression amount is equal to or less than a predetermined threshold value, and therefore it is determined in S10 that the brake is not operated (S10). Y). In addition, since the vehicle has been climbed, in S12, the climbing determination unit 74 determines that the vehicle has not climbed the step (N in S12). When the preliminary braking flag has already been set (Y in S16), the preliminary braking flag setting unit 80 determines the vehicle speed detected by the vehicle speed sensor and the predetermined vehicle speed stored in the riding determination criterion storage unit 72. To determine whether the detected vehicle speed is equal to or lower than the threshold (S18). This threshold is set to a relatively small value, for example, about 2 km / h. Further, this threshold value may be zero.

  When the preliminary braking flag setting unit 80 determines that the vehicle speed is higher than the threshold (N in S18), the preliminary braking flag is maintained in the set state (S14). As a result, the braking response when the brake operation by the driver is performed thereafter is maintained well.

  Thereafter, when the driver depresses the brake pedal, the brake determination unit 78 determines that the driver has performed a brake operation (N in S10). Next, it is determined whether or not the preliminary braking flag is set (S16). If the preliminary braking flag is set (Y in S16), it is determined whether or not the vehicle speed is equal to or lower than the threshold value (S18). . When the vehicle speed becomes equal to or lower than a predetermined threshold value due to the driver's brake operation (Y in S18), the vehicle is decelerated to such an extent that it can be stopped at a desired position only by the driver's brake operation. Cancels the preliminary braking flag (S20). As a result, since the execution of the preliminary braking control by the actuator control unit 84 is stopped, the increase in the wheel cylinder pressure stops and the brake pad moves away from the position close to the disk. Further, the vehicle stops at a desired position by the driver's brake operation. When it is determined that the preliminary braking flag is not set (N in S16), the processes in S14, S18, and S20 are not executed.

  On the other hand, if the vehicle speed has not decreased to a predetermined threshold value or less despite the driver's braking operation (N in S18), the preliminary braking flag setting unit 80 maintains the preliminary braking flag set. (S14). As a result, even after the vehicle has stepped on the level difference, the execution of the preliminary braking control is not stopped until the vehicle speed is lowered to such an extent that the driver can quickly stop at the desired position by the brake operation. The braking response when the brake operation is performed is maintained well.

  As described above, according to the present embodiment, in preparation for the brake operation by the driver after the vehicle has climbed the step, the wheel cylinder pressure is increased, so that the braking responsiveness at the time of the brake operation by the driver is increased. Can be improved. In addition, since the vehicle can be stopped quickly by this, overrun after stepping on the step can be prevented.

  Further, since the threshold relating to the vehicle speed used for the determination in S18 is set to a relatively small value, the actuator control unit 84 basically performs the preliminary braking control when climbing the step at a low speed such as garage entry. Accordingly, since the vehicle does not travel at a high speed while being subjected to the preliminary braking control, energy is not lost, and the influence on fuel consumption and wear of the brake friction material can be suppressed.

  The present invention has been described based on the embodiments. The embodiments are exemplifications, and it will be understood by those skilled in the art that various modifications can be made to combinations of the respective constituent elements and processing processes, and such modifications are within the scope of the present invention. .

  In the embodiment described above, the boarding determination unit 74 determines whether or not the vehicle is riding on a step based on the amount of change in the torque and the vehicle speed, or the request and the vehicle speed from the driver or the driving support system. The determination method is not limited to this. For example, it may be determined that the vehicle is riding on a step when the vehicle speed decreases beyond an amount corresponding to the change amount of the engine output, although the change amount of the engine output is small or almost absent. Also, in this case, in addition to the engine output, the climbing of the step is determined based on the detected value or the calculated value of the physical quantity indicating the magnitude of the engine output, such as the accelerator pedal opening, the engine throttle opening, the engine intake air amount, and the fuel injection amount. Is also possible.

  Furthermore, in the above-described embodiment, the climbing of the step is determined using the engine torque or the like and the vehicle speed. However, an acceleration sensor (front-rear G sensor) that detects acceleration is provided, and the climbing of the step is detected using the detected acceleration. May be determined. At this time, for example, when the acceleration sensor detects a deceleration exceeding an amount corresponding to the change amount of the engine output, it is determined that the vehicle is riding on a step. Also by these, it can be accurately determined whether or not the vehicle is on a step.

  Alternatively, a pitching sensor may be provided in the vehicle, and when the pitching sensor detects a change in the pitch of the vehicle that is equal to or greater than a predetermined value, it may be determined that the vehicle is riding on a step. Here, the pitching sensor may be a sensor that detects a pitch rate, a front-rear difference in vehicle height, or a front-rear difference in suspension stroke. Moreover, you may determine climbing of a level | step difference by arbitrary combinations of this Embodiment and the modification which were mentioned above. Also by these, it can be accurately determined whether or not the vehicle is on a step.

1 is a system diagram showing a vehicle braking device in an embodiment. It is a control block diagram for demonstrating the preliminary braking control performed by ECU. It is a flowchart which shows the process of the setting and cancellation | release of a preliminary brake flag by ECU.

Explanation of symbols

  10 vehicle braking device, 20FL, 20FR, 20RL, 20RR wheel cylinder, 40FR, 40FL, 40RR, 40RL pressure increasing valve, 42FR, 42FL, 42RR, 42RL pressure reducing valve, 44FR, 44FL, 44RR, 44RL cylinder pressure sensor, 200 ECU, 46 Stroke sensor, 60 Throttle opening sensor, 62 Vehicle speed sensor, 70 Torque calculation unit, 72 Riding determination reference storage unit, 74 Riding determination unit, 78 Brake determining unit, 80 Preliminary braking flag setting unit, 84 Actuator control unit, 100 Hydraulic actuator, 200 ECU, 300 travel support ECU.

Claims (4)

A vehicle braking device for braking a vehicle,
Braking force applying means for applying a braking force to the wheels of the vehicle;
Determining means for determining whether or not the vehicle is on a step;
Control means for operating the braking force applying means to such an extent that substantially no braking force is applied to the wheels when the determining means determines that the vehicle is riding on a step;
A vehicle braking device comprising:   The determination means is configured to determine the vehicle speed according to the request of at least one of the driver and the driving support system even when the predetermined output request to the driving source of the vehicle is made by at least one of the driver and the driving support system. The vehicle braking device according to claim 1, wherein when it is not obtained, it is determined that the vehicle is on a step.   The control means generates a command for operating the braking force applying means to such an extent that substantially no braking force is applied to the wheels when the determining means determines that the vehicle is on a step. The vehicle braking device according to claim 1, wherein the command is canceled when the vehicle speed drops below a predetermined value after the vehicle has climbed a step. An overrun prevention method for preventing an overrun after a vehicle has climbed a step using a braking force applying means for applying a braking force to a wheel of the vehicle,
Determining whether the vehicle is on a step;
Activating the braking force applying means to the extent that substantially no braking force is applied to the wheels when it is determined that the vehicle is riding on a step;
The overrun prevention method characterized by including.

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