JP2012214190A - Braking power control system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a braking power control system capable of rapidly restricting the movement of a vehicle at an emergency stop.SOLUTION: In the braking power control system 12, there is included movement restricting means 22 and 62a-62d for regulating the movement of the vehicle 10 when the vehicle 10 is parked. When an emergency brake control means 118 operates to determine that the vehicle 10 stops, the movement restricting means 22 and 62a-62d restrict the movement of the vehicle 10 even in the case that a driver does not perform a parking operation.

Description

  The present invention relates to a braking force control device such as an electric parking brake that restricts movement of a vehicle.

  For example, an electric parking apparatus that operates by setting the shift position to “P” (parking) is known (Patent Document 1). In Patent Document 1, when the shift position is other than “P”, “N” (neutral) and “R” (reverse), the foot brake is operated, and when the vehicle speed becomes zero, the electric parking brake is activated ( wrap up). In this way, the operation of the electric parking brake is automatically controlled to ensure that it is stopped, and it is intended to improve safety by preventing sudden accidents such as sudden accidents and reverse running when starting on slopes. ([0007]). In Patent Document 1, when the shift position is “N”, if the steering torque is not detected or if the driver is not in the driver's seat, the electric parking brake is automatically activated ([0028]).

  Also known is a braking force control device that controls the braking force applied to the wheels during traveling. Among such braking force control devices, there are those related to an anti-lock brake system (ABS) for preventing wheel lock (Patent Documents 2 to 4), and those related to an emergency brake system for increasing brake fluid pressure in an emergency (patent). Reference 4).

  In Patent Document 2, the target wheel speed (VWt) is calculated based on the vehicle body speed (VR0), a predetermined road surface friction coefficient (μ), and a predetermined constant (a) ([0036], [0037], [0055]). Then, the brake torque (T) of each wheel is controlled so that the wheel speed becomes the target wheel speed ([0038] to [0042], [0056] to [0060]).

  Patent Document 3 discloses a technique using antilock brake control, traction control, and directional stability control (summary, claim 1). In Patent Document 3, a target wheel speed serving as a reference for maintaining the directional stability of a vehicle is calculated, and a pressure increase speed or a pressure reduction speed of a wheel brake is determined based on the target wheel speed (summary, claim 1). . In Patent Document 3, the target wheel speed is set in consideration of the yaw rate ([0059]).

  In Patent Document 4, brake assist control for increasing the braking force by the driver's brake operation and automatic brake control for automatically generating the braking force are used (summary, claim 1).

JP 2006-027415 A JP 2009-274582 A JP 11-059388 A JP 2008-307999 A

  As described above, in Patent Document 1, when the shift position is other than “P”, “N”, and “R”, the foot brake is operated, and when the vehicle speed becomes zero, the electric parking brake is activated. This means that Patent Document 1 mainly focuses on assisting the driver's operation during normal driving.

  By the way, when emergency brake control like patent document 4 is performed, in order to avoid that a vehicle starts moving without a driver | operator's operation after a vehicle speed becomes zero, it is preferable to control a movement of a vehicle rapidly. There can be.

  In this regard, in Patent Document 1, when the shift position is “N”, the steering brake is automatically activated when the steering torque is not detected or the driver is not in the driver's seat ([0028]), but the vehicle There is still room for improvement in terms of movement restrictions.

  The present invention has been made in consideration of such problems, and an object of the present invention is to provide a braking force control device capable of quickly regulating the movement of a vehicle at an emergency stop.

  The braking force control device according to the present invention provides a brake fluid pressure higher than a normal brake fluid pressure in an emergency in which there is a high possibility of contact between a vehicle body speed detecting means for detecting a vehicle body speed of the vehicle and an obstacle around the vehicle. Emergency brake control means for generating the vehicle, further comprising movement restriction means for restricting movement of the vehicle when the vehicle is parked, wherein the movement restriction means is activated when the emergency brake means is activated. When it is determined that the vehicle has stopped, the movement of the vehicle is restricted even when there is no parking operation by the driver.

  According to this invention, when the emergency brake is activated and the vehicle is stopped, the movement of the vehicle is restricted even when the driver does not perform a parking operation. Thereby, even if the driver goes out of the vehicle without performing the parking operation after the operation of the emergency brake, for example (in the case of a slope), the vehicle is prevented from moving due to the weight of the vehicle or due to an external force. It becomes possible.

  The movement restricting means includes an actuator for restricting movement of the vehicle, and the operating speed of the actuator is higher when the emergency brake control means is activated and the vehicle is stopped. It may be larger than when the vehicle stops without operating. As a result, when the emergency brake control means is not operating normally, even if the actuator operating speed is suppressed in consideration of the noise of the actuator, the actuator operating speed is increased when the emergency brake control means is operated. By doing so, it becomes possible to quickly regulate the movement of the vehicle.

  The movement restricting means may restrict the movement of the vehicle on condition that the distance from the obstacle when the vehicle body speed becomes zero is equal to or less than a predetermined value. This makes it possible to quickly restrict the movement of the vehicle even when there is no need for a parking operation by the driver only when there is a high necessity for restricting the movement during an emergency stop.

  The emergency brake control means includes an emergency automatic brake means for automatically increasing the brake fluid pressure by the pressurizing means, and an emergency brake for increasing the brake fluid pressure generated by the operation of the driver by the pressurizing means. Assist means, and the emergency brake assist means is activated when a contact margin with respect to the obstacle is larger than the emergency automatic brake means, and the movement restricting means maintains the vehicle in a stopped state. The emergency brake assisting means, comprising: a pressure reducing means for reducing the brake fluid pressure so as to become a predetermined brake fluid pressure set for the purpose; and a control valve for holding the predetermined brake fluid pressure after the pressure reducing means is operated. The amount of operation of the decompression means may be increased when the emergency is activated than when the emergency automatic brake means is activated.

  As a result, when the emergency brake assist means is activated, the brake fluid pressure decreases greatly. For this reason, the brake hydraulic pressure applied to the pressure reducing means after the emergency brake assist means is activated becomes low, and it is possible to avoid wear of the pressure reducing means due to the addition of the brake hydraulic pressure. In addition, for example, when a solenoid valve is used as the pressure reducing means, it is possible to suppress current consumption necessary for maintaining the open / close state of the solenoid valve.

  The movement restricting means is an electric parking brake operated by an electric actuator, and when the distance between the vehicle and the obstacle is equal to or less than a predetermined value, the closer the distance between the vehicle and the obstacle, the closer the electric actuator The operating speed may be increased. As a result, even when the emergency brake control means is not operating normally, even if the electric actuator operating speed is suppressed in consideration of the noise of the electric actuator, etc. By increasing the operating speed of the electric actuator according to the possibility of contact, the movement of the vehicle can be quickly regulated.

  The parking control means controls the opening and closing of a second control valve provided between the master cylinder and the wheel cylinder, and maintains the brake fluid pressure at a second predetermined brake fluid pressure to restrict the movement of the vehicle. The operation amount or the operation speed of the second control valve may be increased as the distance between the vehicle and the obstacle is equal to or smaller than a second predetermined value and the distance between the vehicle and the obstacle is smaller. The emergency brake control means is activated by increasing the operating amount or operating speed of the second control valve as the distance between the vehicle and the obstacle is equal to or less than a second predetermined value and the distance between the vehicle and the obstacle is smaller. When the vehicle stops in an emergency, the movement of the vehicle can be quickly regulated by increasing the operation amount or the operation speed of the second control valve according to the possibility of contact with the obstacle.

  According to this invention, when the emergency brake is activated and the vehicle is stopped, the movement of the vehicle is restricted even when the driver does not perform a parking operation. Thereby, even if the driver goes out of the vehicle without performing the parking operation after the operation of the emergency brake, for example (in the case of a slope), the vehicle is prevented from moving due to the weight of the vehicle or due to an external force. It becomes possible.

1 is a block configuration diagram of a vehicle having a braking force control device according to an embodiment of the present invention. It is a schematic block diagram of the brake machine system in the said embodiment. It is a flowchart which controls the said brake mechanical system. It is explanatory drawing regarding selection of the brake mode in the said embodiment. It is a figure which shows the on-off control of the opening / closing control of an IN valve, an OUT valve, and a regulator valve according to ABS control etc. in the said embodiment. It is a time chart which shows an example in the case of restrict | limiting the movement of the said vehicle by operating an electric parking brake, after performing ABS control and automatic brake control, and stopping the said vehicle. It is a time chart which shows an example when the movement of the said vehicle is controlled by operating the said electric parking brake after performing the said ABS control and brake assist control, and stopping the said vehicle. It is a time chart which shows an example when the movement of the said vehicle is controlled by controlling the pressure of a wheel cylinder, after performing the said ABS control and the said automatic brake control, and stopping the said vehicle. 7 is a time chart illustrating an example of restricting movement of the vehicle by controlling the pressure of the wheel cylinder after the ABS control and the brake assist control are executed to stop the vehicle. It is a time chart which shows an example in the case of restrict | limiting the movement of the said vehicle according to the relative distance with an obstruction immediately after performing the said ABS control and the said brake assist control, and stopping the said vehicle.

A. Embodiment 1 FIG. Configuration of Vehicle 10 (1) Overall Configuration FIG. 1 is a block configuration diagram of a vehicle 10 (hereinafter also referred to as “own vehicle 10”) having a braking force control device 12 according to an embodiment of the present invention. The braking force control device 12 includes a sensor group 14 that performs various detections, and a brake mechanical system 16 that applies a braking force Fb to the wheels 18fl, 18fr, 18rl, and 18rr (hereinafter collectively referred to as “wheels 18”). , An alarm device 20, an electric parking brake 22 (hereinafter referred to as "EPB22"), an electric parking brake setting switch 24 (hereinafter referred to as "EPB setting switch 24" or "switch 24"), and a detection value of the sensor group 14. And an electronic control unit 26 (hereinafter referred to as “ECU 26”) for controlling the brake mechanical system 16 and a mechanical parking brake 28.

(2) Sensor group 14
As shown in FIG. 1, the sensor group 14 includes a radar 30, a yaw rate sensor 32, a rudder angle sensor 34, a torque sensor 36, a vehicle body speed sensor 38 (vehicle speed sensor), wheel speed sensors 40a to 40d, a front and rear G sensor 42, A lateral G sensor 44, a first operation amount sensor 46, and a second operation amount sensor 48 are included.

  The radar 30 is provided in a front grill part (not shown) or the like, transmits an electromagnetic wave such as a millimeter wave toward the front of the vehicle 10 as a transmission wave, and reaches an obstacle (for example, a preceding vehicle) based on the reflected wave. Distance (relative distance Dr) [m], the direction from the vehicle 10 and the size of the obstacle are detected and transmitted to the ECU 26. For example, an image sensor may be used instead of the radar 30. The yaw rate sensor 32 detects the yaw rate Yr generated in the vehicle 10. The steering angle sensor 34 detects the steering angle θs of the steering handle 50 (steering wheel). The torque sensor 36 detects a torque TQ applied to the steering handle 50.

  The vehicle body speed sensor 38 calculates a vehicle body speed Vv [km / h] based on a first Hall element (none of which is shown) that detects the rotation of the transmission countershaft and the output of the first Hall element. 1 calculating part (not shown). The first calculation unit may be provided in the ECU 26.

  The wheel speed sensors 40a to 40d are a second hall element (not shown) that detects the rotation of each wheel 18, and a wheel speed Vw1 of each wheel 18fl, 18fr, 18rl, 18rr based on the output of the second hall element. , Vw2, Vw3, Vw4 (hereinafter collectively referred to as “wheel speed Vw”) [km / h], a second calculation unit (not shown). The second calculation unit may be provided in the ECU 26.

  The longitudinal G sensor 42 is an acceleration sensor and detects longitudinal G (longitudinal acceleration) generated in the vehicle 10. The lateral G sensor 44 is an acceleration sensor and detects lateral G (lateral acceleration) generated in the vehicle 10. The first operation amount sensor 46 detects the operation amount θa of the accelerator pedal 52. The second operation amount sensor 48 detects the operation amount θb of the brake pedal 54.

(3) Brake machine system 16
FIG. 2 shows a schematic configuration diagram of the brake mechanical system 16. As shown in FIG. 2, the brake mechanical system 16 includes a master cylinder 60, wheel cylinders 62a to 62d, IN valves 64a to 64d, OUT valves 66a to 66d, regulator valves 68a and 68b, suction valves 70a and 70b, a pump 72a, 72b, a pump motor 74, reservoirs 76a, 76b, damper chambers 78a, 78b, check valves 80a-80d, 82a, 82b, 84a, 84b, 86a, 86b, and a pressure gauge 88.

  The IN valves 64a to 64d and the regulator valves 68a and 68b are normally open solenoid valves, and the OUT valves 66a to 66d and the suction valves 70a and 70b are normally closed solenoid valves. Each of the valves 64a to 64d, 66a to 66d, 68a, 68b, 70a, and 70b opens and closes based on a command from the ECU 26 (details will be described later). The pressure gauge 88 detects the pressure Pi in the pipe 90.

(4) Alarm device 20
The alarm device 20 includes a speaker (not shown) and emits a warning sound to the driver under a command from the ECU 26.

(5) EPB 22 and EPB setting switch 24
The EPB 22 locks the drive wheels of the wheels 18 and restricts the movement of the vehicle 10. The EPB 22 includes an EPB motor 92 (electric actuator) (FIG. 1), and can switch the EPB 22 between ON (restricted state) and OFF (non-restricted state) according to the driving of the EPB motor 92. As EPB22, the thing of patent document 1 or Unexamined-Japanese-Patent No. 2008-174189 can be used, for example.

  The EPB setting switch 24 switches whether or not the EPB 22 can be operated. For example, when an ignition switch (or vehicle operation mode) (not shown) is on and the switch 24 is on, the EPB 22 is powered on, and the EPB motor 92 is operated according to the vehicle body speed Vv and the like. Further, when the switch 24 is turned off, the EPB 22 is turned off.

(6) ECU26
As shown in FIG. 1, the ECU 26 includes an input / output unit 100, a calculation unit 102, and a storage unit 104 as hardware. The arithmetic unit 102 of the present embodiment controls the brake mechanical system 16 based on a program stored in the storage unit 104, thereby providing an antilock brake system function 110 (hereinafter referred to as “ABS function 110”) and a traction control function. 112, a skid prevention function 114, an avoidance operation support function 116, and an emergency brake function 118 are realized.

  The ABS function 110 is a function that prevents the wheels 18 from being locked when a braking force Fb is applied from the brake mechanical system 16 to the wheels 18 (during brake operation). The traction control function 112 is a function of controlling the brake fluid pressure Pb of the wheel cylinders 62a to 62d corresponding to the drive wheels that are likely to fall into an excessive slip state during non-braking operation among the wheels 18 that are drive wheels. The traction control function 112 is used, for example, to prevent the wheels 18 from idling during acceleration. The skid prevention function 114 is a function of preventing a skid when the vehicle 10 turns a curve or the like.

  The avoidance operation support function 116 is a function that assists the operation when the driver operates the steering handle 50 to avoid the vehicle 10 from an obstacle. The term “assistance” as used herein includes a function of assisting steering in an avoiding direction using an auxiliary motor (not shown) and a function of applying resistance to the steering in a steering direction where steering should not be performed by using the auxiliary motor. .

  The emergency brake function 118 further includes a brake assist function 120 and an automatic brake function 122. The brake assist function 120 is a function for increasing the brake fluid pressure Pb generated by the operation of the brake pedal 54 by the driver to be higher than usual. The automatic brake function 122 is a function for automatically increasing the brake hydraulic pressure Pb in each wheel cylinder 62a to 62d (without operating the brake pedal 54 by the driver). As a method of increasing the brake fluid pressure Pb in the brake assist function 120 and the automatic brake function 122, for example, a method using pumps 72a and 72b, or a method using an accumulator or motor that increases the fluid pressure of the master cylinder 60 is used. Can be mentioned.

2. Control of Brake Machine System 16 (1) Flow of Control of Brake Machine System 16 FIG. 3 shows a flowchart for controlling the brake machine system 16. In step S <b> 1, the ECU 26 acquires a detection value from the sensor group 14. At this time, the values of the various sensors in the sensor group 14 can be used as they are in the ECU 26, and there are those that require specific numerical values to be calculated by calculation processing in the calculation unit 102. For this reason, in step S1, not only a detected value is acquired but also a calculation process is executed to obtain a more specific numerical value.

  In step S2, the ECU 26 calculates a control parameter for emergency brake control (emergency brake function 118) based on the detection value acquired in step S1. The control parameters in this embodiment are a relative speed Vr and a contact margin time (TTC: Time To Collision).

The ECU 26 calculates the relative speed Vr [km / h] between the host vehicle 10 and the obstacle based on the relative distance Dr from the radar 30. The relative speed Vr is calculated based on the following formula (1).
Vr (x) = {Dr (x) -Dr (x-1) / Tc} (1)

  In the above equation (1), Tc indicates the calculation cycle [s] (fixed value), x indicates a value in the current calculation cycle Tc, and x−1 indicates a value in the previous calculation cycle Tc.

Next, the ECU 26 calculates TTC using the following equation (2).
TTC (x) = Dr (x) / Vr (x) (2)

  In step S3 of FIG. 3, the ECU 26 calculates the vehicle state. The vehicle state here includes a braking state in which a braking force Fb is applied from the brake mechanical system 16 to the wheels 18, an acceleration state in which the vehicle 10 is accelerating, and a driver operating the steering handle 50. Thus, the steering state in which the steering angle θs is changing and the normal state that is neither of the above states are included. Therefore, the ECU 26 calculates whether the vehicle state is a braking state, an acceleration state, a steering state, or a normal state. For the calculation, the detection value acquired in step S1 is used.

  In step S4, the ECU 26 selects a mode (brake mode) of the emergency brake function 118. The brake mode includes a normal mode, an alarm mode, a brake assist mode, a first automatic brake mode, and a second automatic brake mode. Hereinafter, the first automatic brake mode and the second automatic brake mode are collectively referred to as an automatic brake mode.

  FIG. 4 is an explanatory diagram relating to selection of the brake mode. As can be seen from FIG. 4, in the present embodiment, the brake mode is set based on the relative speed Vr and TTC. That is, when the vehicle 10 approaches the obstacle and the combination of the relative speed Vr and the TTC falls below the emergency reference time line, the ECU 26 switches from the normal mode to the alarm mode. Then, the ECU 26 issues a warning to the driver via the warning device 20. The alarm may be one-time output, intermittent output, or continuous output.

  When the vehicle 10 further approaches the obstacle and the combination of the relative speed Vr and TTC falls below the brake assist reference time line, the ECU 26 selects the brake assist mode. When the driver operates the brake pedal 54 with the brake assist mode selected, the ECU 26 controls the brake mechanical system 16 according to the operation amount θb of the brake pedal 54 to increase the brake hydraulic pressure Pb. . When the relative speed Vr is equal to or higher than the predetermined value Vr2 (FIG. 4), the alarm reference time line and the brake assist reference time line coincide with each other, and the alarm mode and the brake assist mode are selected at the same time.

  If the vehicle 10 further approaches the obstacle and the combination of the relative speed Vr and the TTC falls below the automatic brake 1 reference time line, the ECU 26 selects the first automatic brake mode. While the first automatic brake mode is selected, the ECU 26 controls the brake mechanical system 16 independently of the operation amount θb of the brake pedal 54 to increase the brake hydraulic pressure Pb.

  When the vehicle 10 further approaches the obstacle and the combination of the relative speed Vr and the TTC falls below the automatic brake 2 reference time line, the ECU 26 selects the second automatic brake mode. While the second automatic brake mode is selected, the ECU 26 controls the brake mechanical system 16 independently of the operation amount θb of the brake pedal 54 to increase the brake hydraulic pressure Pb. The degree of increase here is greater than that in the first automatic brake mode. When the relative speed Vr is equal to or less than the predetermined value Vr1 (FIG. 4), the automatic brake 1 reference time line and the automatic brake 2 reference time line coincide with each other, and the second automatic brake mode is selected with priority. Hereinafter, the first automatic brake control and the second automatic brake control are collectively referred to as “automatic brake control”. The brakes by the first automatic brake control and the brakes by the second automatic brake control are collectively referred to as “automatic brake”.

  When the combination of the relative speed Vr and the TTC exceeds the emergency reference time line, none of the above modes (alarm mode, brake assist mode, first automatic brake mode, and second automatic brake mode) is selected, and the normal mode is Selected. In the normal mode, a normal brake fluid pressure Pb is generated.

  Moreover, about the further detail of the process accompanying FIG. 4, the thing of patent document 3 can be used (for example, refer FIG. 4, paragraphs [0031]-[0045] of patent document 4).

  In the present embodiment, the ABS control can be executed in parallel with the emergency brake control. As described above, the ABS control prevents the wheels 18 from being locked when the braking force Fb is applied from the brake mechanical system 16 to the wheels 18 (during brake operation).

  In the ABS control, the valve mode is selected according to the target slip ratio St and the target wheel speed Vwt. The valve mode of the present embodiment includes a pressure increasing mode for increasing the brake fluid pressure Pb applied to the wheel cylinders 62a to 62d, a pressure reducing mode for decreasing the brake fluid pressure Pb applied to the wheel cylinders 62a to 62d, and the wheel cylinders 62a to 62d. There is a holding mode in which the brake fluid pressure Pb applied to 62d is held.

  The target slip ratio St is a target value of the slip ratio S of the wheel 18. The slip rate S is obtained by dividing the difference between the vehicle speed Vv and the wheel speed Vw by the vehicle speed Vv {S = (Vv−Vw) / Vv}. In the present embodiment, the target slip ratio St is a fixed value. Instead, it may be variable depending on the type of road surface (asphalt, gravel road, etc.) on which the vehicle 10 is traveling, the road surface condition (dry, wet, etc.), the vehicle body speed Vv, and the like. The type of the road surface can be acquired by, for example, a navigation device (including a portable information terminal having a navigation device function). The road surface state can be estimated by, for example, a road surface friction coefficient μ calculated by automatically applying a braking force instantaneously to the wheel 18.

  The target wheel speed Vwt can be calculated according to the vehicle body speed Vv and the target slip ratio St. For example, the difference between the target wheel speed Vwt and the vehicle body speed Vv is set in advance so that the target wheel speed Vwt is equal to or less than the vehicle body speed Vv, and the target wheel speed Vwt can be calculated using the difference. . The difference can be set according to the target slip ratio St.

  When the difference D1 (= Vw−Vwt) between the actual wheel speed Vw and the target wheel speed Vwt falls below the threshold value TH_D1, the ECU 26 temporarily selects the decompression mode, and then the wheel speed Vw becomes equal to the target wheel speed Vwt. Select hold mode until equal. When the actual wheel speed Vw exceeds the target wheel speed Vwt, the ECU 26 selects the pressure increasing mode, and then selects the pressure increasing mode until the wheel speed Vw becomes equal to the target wheel speed Vwt.

  Returning to FIG. 3, in step S5, the ECU 26 calculates the braking force Fb by the brake mechanical system 16 according to the brake mode selected in step S4. For example, when the normal mode or the alarm mode is selected, the ECU 26 does not generate the additional braking force Fb by the brake mechanical system 16 but generates the normal brake fluid pressure Pb according to the operation of the brake pedal 54. Thus, the braking force Fb by the brake mechanical system 16 is controlled.

  Further, when the brake assist mode is selected, the ECU 26 adds an additional brake fluid pressure Pb (additional braking force Fb) to be added to the normal brake fluid pressure Pb generated in accordance with the operation of the brake pedal 54. Calculation is performed according to the operation amount θb of the brake pedal 54 or the depression force.

  Further, when the first automatic brake mode is selected, the ECU 26 calculates an additional braking force Fb generated by the brake mechanical system 16 regardless of the operation of the brake pedal 54. Similarly, when the second automatic brake mode is selected, the ECU 26 calculates an additional braking force Fb generated by the brake mechanical system 16 regardless of the operation of the brake pedal 54. As described above, when the relative speeds Vr and TTC are equal, the additional braking force Fb in the second automatic brake mode is larger than the additional braking force Fb in the first automatic brake mode.

  In step S6, the ECU 26 determines whether or not the vehicle 10 has stopped after the brake assist mode or the automatic brake mode is selected. Whether the brake assist mode or the automatic brake mode is selected is determined by setting a flag (brake assist flag or automatic brake flag) indicating that when the brake assist mode or the automatic brake mode is selected. be able to. In the present embodiment, when the brake assist flag or the automatic brake flag is set, the flag is reset when a predetermined time elapses after the vehicle 10 stops (details will be described later). For this reason, the flag is not reset at least until the vehicle 10 stops. Further, whether or not the vehicle 10 has stopped is determined based on whether or not the vehicle body speed Vv is zero.

  When neither the brake assist mode nor the automatic brake mode is selected or the vehicle 10 is not stopped (S6: NO), the process proceeds to step S9. When the vehicle 10 stops after the brake assist mode or the automatic brake mode is selected (S6: YES), in step S7, the ECU 26 calculates a control parameter used in stop control described later. The parameter in this embodiment is the period T1 [s]. As will be described later, the relative distance Dr or the like can be used as the parameter.

  In step S8, the ECU 26 executes stop control. In the stop control, the on / off control of the EPB 22 and the operating speed Vm of the EPB motor 92 are determined.

  Specifically, regarding the on / off control of the EPB 22, the ECU 26 checks whether or not the elapsed time T2 from the stop of the vehicle 10 is equal to or longer than the period T1. When the elapsed time T2 becomes equal to or longer than the period T1, the ECU 26 turns on the EPB 22 and restricts the movement of the vehicle 10.

  The operating speed Vm of the EPB motor 92 affects the time from when the EPB motor 92 starts operating until the wheels 18 are locked. In the present embodiment, when the vehicle stops without performing the brake assist control and the automatic brake control, the operating speed Vm of the EPB motor 92 is suppressed in consideration of the noise of the EPB motor 92 and the like. However, when the vehicle stops after executing the brake assist control or the automatic brake control, the movement speed of the vehicle 10 is quickly regulated by increasing the operating speed Vm of the EPB motor 92 in consideration of the possibility of contact with an obstacle. .

  In step S9, the ECU 26 controls the valves 64a to 64d, 66a to 66d, 68a, and 68b according to the result of step S5 (S6: NO) or the result of step S8 (S6: YES). .

  FIG. 5 is a diagram showing the open / close control of the IN valves 64a to 64d, the OUT valves 66a to 66d, the regulator valves 68a and 68b and the on / off control of the pumps 72a and 72b in accordance with the ABS control or the like. As shown in FIG. 5, in the normal control (pattern 1) without the ABS control, the normally open type IN valves 64a to 64d and the regulator valves 68a and 68b are all open (OFF), and the normally closed type OUT is used. The valves 66a to 66d are closed (OFF). The pumps 72a and 72b are turned off.

  In ABS control (pattern 2) without brake assist control or automatic brake control, the regulator valves 68a and 68b are opened (OFF), and the pumps 72a and 72b are turned on (ON), and the actual wheel speed is set. The IN valves 64a to 64d and the OUT valves 66a to 66d are opened and closed (ON / OFF) according to the relationship between Vw and the target wheel speed Vwt. That is, when the wheel speed Vw exceeds the target wheel speed Vwt, the IN valves 64a to 64d are opened and the OUT valves 66a to 66d are closed. When the difference D1 between the wheel speed Vw and the target wheel speed Vwt is lower than the threshold value TH_D1, the IN valves 64a to 64d are closed and the OUT valves 66a to 66d are opened. When the wheel speed Vw is equal to the target wheel speed Vwt, the IN valves 64a to 64d and the OUT valves 66a to 66d are all closed.

  In the ABS control (pattern 3) accompanied by the brake assist control, the regulator valves 68a and 68b are controlled to open and close according to the differential pressure between the master cylinder 60 side and the wheel cylinders 62a to 62d side. In addition, the regulator valves 68a and 68b are slightly closed with a relatively small drive current Irv and the pumps 72a and 72b are turned on, and the relationship between the actual wheel speed Vw and the target wheel speed Vwt is similar to the pattern 2. Accordingly, control may be performed to open and close the IN valves 64a to 64d and the OUT valves 66a to 66d. As a result, it is possible to assist the operation of the brake pedal 54 by generating the brake fluid pressure Pb by the brake assist control based on the braking by the brake fluid pressure Pb accompanying the operation of the brake pedal 54.

  In the ABS control (pattern 4) with automatic brake control, the regulator valves 68a and 68b are closed. In addition, when the regulator valves 68a and 68b are largely closed by a relatively large drive current Irv and the pumps 72a and 72b are turned on, the actual wheel speed Vw and the target wheel speed Vwt are similar to those in the patterns 2 and 3. Control may be performed to open and close the IN valves 64a to 64d and the OUT valves 66a to 66d according to the relationship. Therefore, compared with the pattern 3, in the pattern 4, the brake fluid pressure Pb applied to the wheel cylinders 62a to 62d from the pumps 72a and 72b is increased, and a larger braking force Fb can be generated. Thereby, it becomes possible to perform braking by the brake fluid pressure Pb generated by the automatic brake control.

(2) Specific example of control of brake mechanical system 16 (a) When executing ABS control and automatic brake control FIG. 6 is a time chart showing an example when executing ABS control and automatic brake control (the above pattern 4). It is. In FIG. 6, in the ABS control, the ECU 26 sets the target wheel speed Vwt, and controls the brake mechanical system 16 so that the wheel speed Vw becomes equal to the target wheel speed Vwt. That is, the ECU 26 brings the wheel speed Vw closer to the target wheel speed Vwt while switching the valve mode of the brake mechanical system 16 between the pressure increasing mode, the pressure reducing mode, and the holding mode. At this time, since the automatic brake is operating, the automatic brake flag is set (turned on). Further, since the brake pedal 54 is not depressed, the pressure Pmc of the master cylinder 60 remains zero.

  When the vehicle body speed Vv becomes zero at time t1, the ECU 26 starts counting the elapsed time T2. At time t2, when the elapsed time T2 becomes equal to or longer than the period T1, the ECU 26 turns on the EPB 22 and lowers (turns off) the automatic brake flag. The stop control is continued until an ignition switch (not shown) is turned off or until the accelerator pedal 52 is depressed and the vehicle 10 starts running again.

(B) Case where ABS control and brake assist control are executed FIG. 7 is a time chart showing an example of the case where the ABS control and brake assist control are executed (the above pattern 3). As in FIG. 6, in FIG. 7, in the ABS control, the ECU 26 sets the target wheel speed Vwt and controls the brake mechanical system 16 so that the wheel speed Vw becomes equal to the target wheel speed Vwt. At this time, since the brake assist is operating, the brake assist flag is set (turned on). Further, the pressure Pmc of the master cylinder 60 becomes the maximum value with the assist operation.

  When the vehicle body speed Vv becomes zero at time t11, the ECU 26 starts counting the elapsed time T2. At time t12, when the elapsed time T2 becomes equal to or longer than the period T1, the ECU 26 turns on the EPB 22 and lowers (turns off) the brake assist flag. Further, the ECU 26 gradually decreases the pressure Pmc of the master cylinder 60 that has been set to the maximum value along with the brake assist to zero.

3. As described above, according to this embodiment, when the emergency brake (brake assist or automatic brake) is activated and the vehicle 10 is stopped, the vehicle 10 can be operated even when there is no parking operation by the driver. Restrict movement. Thus, even if the driver goes out of the vehicle 10 without performing a parking operation after the emergency brake is activated, for example (in the case of a slope), the vehicle 10 is moved by the weight of the vehicle 10 or by an external force. Can be prevented.

  In this embodiment, the operating speed Vm of the EPB motor 92 of the EPB 22 is greater when the emergency brake is activated and the vehicle 10 is stopped than when the vehicle 10 is stopped without the emergency brake being activated. Thereby, even when the operation speed Vm is suppressed in consideration of noise of the EPB motor 92 at the time of a normal stop where the emergency brake is not operated, by increasing the operation speed Vm at the time of an emergency stop where the emergency brake is operated, The movement of the vehicle 10 can be quickly regulated.

B. Modifications It should be noted that the present invention is not limited to the above-described embodiment, and it is needless to say that various configurations can be adopted based on the contents described in this specification. For example, the following configuration can be adopted.

1. Vehicle 10
In the above embodiment, the vehicle 10 is a four-wheeled vehicle, but is not limited thereto, and may be a two-wheeled vehicle, a truck, a bus, or the like.

2. Relative distance Dr
In the above embodiment, the determination of the relative distance Dr between the host vehicle 10 and the obstacle (preceding vehicle) is performed based on the output of the radar 30, but the present invention is not limited to this. For example, the determination using the output from the image sensor May be.

3. Stop Control (1) Conditions for Stop Control In the above embodiment, the selection of the brake assist mode or the automatic brake mode is set as part of the conditions for stop control. However, the present invention is not limited to this. For example, the stop control may be performed only when the automatic brake mode is selected without performing the stop control when the brake assist mode is selected.

(2) Means and Method for Restricting Movement of Vehicle 10 after Stopping In the above embodiment, EPB 22 is used as a means and method for restricting movement of the vehicle 10 after stopping, but the present invention is not limited to this. For example, as described in detail below, the pressure Pwc of the wheel cylinders 62a to 62d can be controlled instead of turning on the EPB 22. Alternatively, the EPB 22 may be turned on and the pressure Pwc of the wheel cylinders 62a to 62d may be controlled.

(A) When the pressure Pwc of the wheel cylinders 62a to 62d is used instead of the EPB 22 when the vehicle stops after the automatic brake mode is activated. FIG. 8 executes ABS control and automatic brake control (the above pattern 4) to stop the vehicle 10. 5 is a time chart illustrating an example of restricting movement of the vehicle 10 by controlling the pressure Pwc of the wheel cylinders 62a to 62d.

  Similar to the example of FIG. 6, in FIG. 8, in the ABS control, the ECU 26 sets the target wheel speed Vwt and controls the brake mechanical system 16 so that the wheel speed Vw becomes equal to the target wheel speed Vwt. At this time, since the automatic brake is operating, the pressure Pwc of the wheel cylinders 62a to 62d becomes the maximum value except for a predetermined period (time t21 to t23) after the wheel speed Vw exceeds the target wheel speed Vwt. . In addition, the automatic brake flag is set (turned on). Further, since the brake pedal 54 is not operated, the pressure Pmc of the master cylinder 60 remains zero.

  When the vehicle speed Vv becomes zero at time t21, the ECU 26 starts counting the elapsed time T2. At the time t22, when the elapsed time T2 becomes equal to or longer than the period T1, the ECU 26 lowers (turns off) the automatic brake flag and controls the pumps 72a and 72b and the pump motor 74 to control the wheel cylinders 62a to 62d. The pressure Pwc is set to the minimum pressure Pwcmin that is the minimum necessary for restricting the movement of the vehicle 10. For example, in a state where the wheel cylinders 62a to 62d are in a state where the vehicle 10 is stopped, the pressure Pwc is decreased while monitoring the wheel speed Vw or the angle of the wheel 18, and if the wheel 18 starts moving, The immediately preceding value can be the minimum pressure Pwcmin. Alternatively, a minimum pressure Pwcmin required to stop the vehicle 10 on a reference road surface (for example, a flat asphalt road or a road surface having a predetermined slope and a road surface friction coefficient μ) is obtained in advance, and stored in the storage unit 104. You can remember it and use it.

  Further, the ECU 26 decreases the drive current Irv of the regulator valves 68a and 68b so that the pressure Prv of the regulator valves 68a and 68b becomes the minimum pressure Prvmin that can maintain the pressure Pwc at the minimum pressure Pwcmin. At time t23, the drive current Irv becomes the minimum drive current Irvmin corresponding to the minimum pressure Prvmin, and when the pressure Prv becomes the minimum pressure Prvmin, the ECU 26 turns off the pumps 72a and 72b.

  The operating speed V1 of the regulator valves 68a and 68b at this time can be set according to the relative distance Dr. That is, when the relative distance Dr is short, the operating speed V1 is increased, and when the relative distance Dr is long, the operating speed V1 is decreased. The operating speed V1 corresponds to the time from when the regulator valves 68a and 68b start operating until the final target opening is reached. In the present embodiment, when the vehicle stops without performing the brake assist mode and the automatic brake control, the operation speed V1 is suppressed in consideration of the power consumption of the regulator valves 68a and 68b. However, when the vehicle stops after executing the brake assist mode or the automatic brake control, the movement of the vehicle 10 is quickly regulated by increasing the operating speed V1 in consideration of the possibility of contact with an obstacle.

(B) When the pressure Pwc of the wheel cylinders 62a to 62d is used instead of the EPB 22 when the vehicle stops after the brake assist mode is activated. FIG. 9 executes the ABS control and the brake assist control (the above pattern 3) to stop the vehicle 10. 5 is a time chart illustrating an example of restricting movement of the vehicle 10 by controlling the pressure Pwc of the wheel cylinders 62a to 62d.

  As in the example of FIG. 7, in FIG. 9, in the ABS control, the ECU 26 sets the target wheel speed Vwt and controls the brake mechanical system 16 so that the wheel speed Vw becomes equal to the target wheel speed Vwt. At this time, since the brake assist is operating, the pressure Pmc of the master cylinder 60 takes a maximum value, and the wheel cylinders 62a to 62d are excluded except for a predetermined period after the wheel speed Vw exceeds the target wheel speed Vwt. The pressure Pwc takes a maximum value. In addition, the brake assist flag is set (turned on).

  When the vehicle speed Vv becomes zero at time t31, the ECU 26 starts counting the elapsed time T2. At time t32, when the elapsed time T2 becomes equal to or greater than the period T1, the ECU 26 lowers (turns off) the brake assist flag, and controls the pumps 72a and 72b and the pump motor 74 to thereby control the wheel cylinders 62a to 62d. The pressure Pwc is set to the minimum pressure Pwcmin. Further, the ECU 26 increases the drive current Irv of the regulator valves 68a and 68b so that the pressure Prv of the regulator valves 68a and 68b becomes the minimum pressure Prvmin. At time t33, when the drive current Irv of the regulator valves 68a and 68b becomes the minimum drive current Irvmin corresponding to the minimum pressure Prvmin, and the pressure Prv becomes the minimum pressure Prvmin, the ECU 26 turns off the pumps 72a and 72b.

  8 and 9, when the brake assist is activated, the operation amount Qv of the regulator valves 68a and 68b may be increased when the automatic brake is activated. The brake fluid pressure Pb applied to the regulator valves 68a and 68b is higher when the brake assist is activated than when the automatic brake is activated. For this reason, by increasing the operation amount Qv when the brake assist is activated, the brake fluid pressure Pb applied to the regulator valves 68a and 68b is reduced, and the wear of the regulator valves 68a and 68b due to the addition of the brake fluid pressure Pb is avoided. It becomes possible to do. Further, since the solenoid valves are used as the regulator valves 68a and 68b, it is possible to suppress the consumption current (drive current Irv) necessary for maintaining the open / close state of the solenoid valves.

(3) Timing for restricting movement of vehicle 10 after stopping In the above-described embodiment (FIGS. 6 and 7) and the modified examples (FIGS. 8 and 9), the movement of vehicle 10 after a lapse of period T1 from the stop of vehicle 10 However, the timing of restricting the movement of the vehicle 10 after the stop is not limited to this. For example, when it is detected that the vehicle 10 has stopped (for example, the vehicle body speed Vv has become zero), the movement of the vehicle 10 can be restricted immediately. At this time, the movement restriction condition may be that the relative distance Dr between the vehicle 10 and the obstacle is not more than a predetermined threshold.

  FIG. 10 is a time chart illustrating an example of the case where the movement of the vehicle 10 is restricted immediately after the vehicle 10 is stopped. In the example of FIG. 10, the movement restriction condition is that the relative distance Dr between the vehicle 10 and the obstacle is equal to or less than a threshold value TH_Dr.

  Until time t41, the vehicle 10 is decelerated while executing ABS control and brake assist control. When the vehicle speed Vv becomes zero at time t41 and the vehicle 10 stops, the ECU 26 determines whether or not the relative distance Dr from the radar 30 at that time is equal to or less than the threshold value TH_Dr. For example, the threshold TH_Dr can be set to a distance (for example, any value between 1 centimeter and 2 meters) that is highly necessary to restrict the movement of the vehicle 10 because the relative distance Dr is too short.

  In the example of FIG. 10, since the relative distance Dr at the time point t41 is equal to or less than the threshold value TH_Dr, the ECU 26 restricts the movement of the vehicle 10 using the wheel cylinders 62a to 62d. Specifically, the ECU 26 lowers (turns off) the automatic brake flag and controls the pumps 72a and 72b and the pump motor 74 so that the pressure Pwc of the wheel cylinders 62a to 62d becomes the minimum pressure Pwcmin. To. Further, the ECU 26 increases the drive current Irv of the regulator valves 68a and 68b so that the pressure Prv of the regulator valves 68a and 68b becomes the minimum pressure Prvmin. At time t42, when the drive current Irv becomes the minimum drive current Irvmin and the pressure Prv becomes the minimum pressure Prvmin, the ECU 26 turns off the pumps 72a and 72b. As a result, it is possible to quickly restrict the movement of the vehicle 10 even when there is no need for a parking operation by the driver only when there is a high necessity for restricting movement during an emergency stop.

  Further, in the example of FIG. 10, at least one of the operation amount Qv and the operation speed V1 of the regulator valves 68a and 68b can be increased as the relative distance Dr is equal to or less than the threshold value TH_Dr and the relative distance Dr is smaller. This makes it possible to quickly regulate the movement of the vehicle 10 by increasing the operating speed V1 of the regulator valves 68a and 68b in accordance with the possibility of contact with an obstacle during an emergency stop when the emergency brake is activated. Moreover, the movement of the vehicle 10 can be more reliably regulated by increasing the operation amount Qv.

  In FIG. 10, the wheel cylinders 62 a to 62 d are used as direct means for regulating the movement of the vehicle 10, but the EPB 22 can be operated instead of or together with this. In this case, the operating speed Vm of the EPB motor 92 can be changed according to the relative distance Dr at the time of stop. For example, the operating speed Vm is increased as the relative distance Dr is shorter, and the operating speed Vm is decreased as the relative distance Dr is longer. As a result, when the emergency brake is activated, even if the operation speed Vm of the EPB motor 92 is suppressed in consideration of the noise of the EPB motor 92 of the EPB 22 at the time of normal stop where the emergency brake is not activated, By increasing the operating speed Vm in accordance with the possibility of contact, the movement of the vehicle 10 can be quickly regulated.

  In addition to or instead of the relative distance Dr detected by the radar 30, a relative distance to an obstacle behind the vehicle detected by a back monitor (not shown) mounted on the vehicle 10 may be used.

DESCRIPTION OF SYMBOLS 10 ... Vehicle (own vehicle) 12 ... Braking force control apparatus 22 ... Electric parking brake (movement control means)
38 ... Vehicle speed sensor (vehicle speed detection means)
60 ... Master cylinders 62a to 62d ... Wheel cylinder (movement restricting means)
64a to 64d ... IN valve (pressure reducing means, second control valve)
66a to 66d ... OUT valve (pressure reducing means)
68a, 68b ... Regulator valve (control valve, second control valve)
72a, 72b ... pump (pressurizing means, depressurizing means)
74 ... Pump motor (pressurizing means, decompressing means)
92 ... EPB motor (actuator)
118 ... Emergency brake function (emergency brake control means)
120 ... Brake assist function (emergency brake assist means)
122 ... Automatic brake function (emergency automatic brake means)
Dr ... Relative distance Pb ... Brake hydraulic pressure Qv ... Operating amount of each valve
TH_Dr ... threshold (predetermined value, second predetermined value)
TTC: Contact margin time (contact possibility, contact margin)
Vm: Operating speed of EPB motor Vv: Vehicle speed V1: Operating speed of each valve

Claims (6)

Vehicle body speed detection means for detecting the vehicle body speed;
A braking force control device comprising: emergency brake control means for generating a brake fluid pressure higher than a normal brake fluid pressure in an emergency in which contact possibility with obstacles around the vehicle is high,
Furthermore, a movement restricting means for restricting movement of the vehicle when the vehicle is parked,
The movement restricting means restricts the movement of the vehicle even when there is no parking operation by the driver when it is determined that the vehicle has stopped due to the operation of the emergency brake means. Power control device. The braking force control apparatus according to claim 1, wherein
The movement restricting means includes an actuator for restricting movement of the vehicle,
The operating speed of the actuator is larger when the emergency brake control means is activated and the vehicle is stopped than when the vehicle is stopped without the emergency brake control means being activated. Braking force control device. The braking force control device according to claim 1 or 2,
The braking force control apparatus, wherein the movement restricting means restricts the movement of the vehicle on condition that a distance from the obstacle when the vehicle body speed becomes zero is a predetermined value or less. The braking force control apparatus according to any one of claims 1 to 3,
The emergency brake control means includes
Emergency automatic braking means for automatically increasing the brake fluid pressure by the pressurizing means;
Emergency brake assist means for increasing the brake fluid pressure generated by the operation of the driver by the pressurizing means,
The emergency brake assist means operates when a contact margin with respect to the obstacle is larger than the emergency automatic brake means,
The movement restricting means is
Pressure reducing means for reducing the brake fluid pressure so that the vehicle has a predetermined brake fluid pressure set to maintain the stationary state;
A control valve that holds the predetermined brake fluid pressure after the pressure reducing means is actuated,
The braking force control device according to claim 1, wherein when the emergency brake assist means is activated, the amount of operation of the pressure reducing means is larger than when the emergency automatic brake means is activated. In the braking force control device according to any one of claims 1 to 4,
The movement restricting means is an electric parking brake operated by an electric actuator,
When the distance between the vehicle and the obstacle is a predetermined value or less, the operating speed of the electric actuator is increased as the distance between the vehicle and the obstacle is shorter. In the braking force control device according to any one of claims 1 to 5,
The parking control means controls the opening and closing of a second control valve provided between the master cylinder and the wheel cylinder, and maintains the brake fluid pressure at a second predetermined brake fluid pressure to restrict the movement of the vehicle. ,
The operation amount or the operation speed of the second control valve is increased as the distance between the vehicle and the obstacle is equal to or less than a second predetermined value and the distance between the vehicle and the obstacle is smaller. Braking force control device.

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