JP7230523B2 - brake controller - Google Patents

Description

The present invention relates to a brake control device.

In recent years, in vehicles such as passenger cars, an electric parking brake (EPB) is used not only for parking in a parking lot, but also for temporary stop while waiting for a signal. In this case, for example, the driver first depresses the brake pedal to apply the hydraulic brake, and then performs the EPB start operation to apply the electric brake while the vehicle is stopped. By doing so, even if the driver takes his/her foot off the brake pedal, the stopped state is maintained, which is convenient.

In that case, for example, according to a technology called DAR (Drive Away Release) control, the driver only has to depress the accelerator pedal to make the vehicle run again. Then, the EPB mechanism operates to move the piston from the lock position to the release position (EPB release). Also, in normal EPB release, a technology is known in which a hydraulic brake mechanism operates to increase the hydraulic pressure to the caliper to a predetermined hydraulic pressure, and after the EPB is released, the hydraulic pressure is released and the vehicle is driven. there is

The reason why the hydraulic pressure is increased before the EPB is released is to sufficiently elastically deform the seal member arranged at the position surrounding the outer periphery of the piston. In other words, the piston can be moved to an appropriate release position by utilizing the force of the elastically deformed seal member tending to return to its original shape.

Japanese Unexamined Patent Application Publication No. 2009-280143

However, in the conventional technology described above, the hydraulic pressure to the caliper starts to rise after the driver steps on the accelerator pedal while the vehicle is stopped, so there is room for improvement in terms of responsiveness.

Accordingly, one of the objects of the present invention is to complete the release control more quickly when the driver performs an operation for causing the vehicle to travel when the electric brake is in the locked state while the vehicle is stopped. It is to provide a brake control device capable of

A brake control device according to the present invention includes, for example, a hydraulic brake device that presses a braking member with hydraulic pressure toward a member to be braked that rotates integrally with a wheel of a vehicle to generate a hydraulic braking force; A brake control device applied to a vehicle, comprising: an electric braking device that presses the braking member toward the braking member by driving a motor to generate an electric braking force. The brake control device includes a control unit that executes hydraulic pressure control by the hydraulic brake device, lock control for generating the electric braking force by the electric braking device, and release control for releasing the electric braking force. have. The control unit executes release preparation control for generating a predetermined hydraulic pressure by the hydraulic brake device when a preset release prediction condition is satisfied in a locked state in which the lock control is completed, and then performs a release preparation control in advance. When the set release start condition is satisfied, the release control is executed. The control unit determines whether or not the release prediction condition is satisfied based on at least one of a steering wheel operation, a driver's attitude, information on a traffic signal in front, and a starting behavior of a vehicle in front, and drives the vehicle. When the driver touches the steering wheel, when the driver is in a driving posture, when the color of the forward traffic light changes from red to blue, when the forward vehicle starts moving forward, and when the forward vehicle When at least one of (1) and (2) is satisfied, it is determined that the release prediction condition is satisfied.

FIG. 1 is a schematic diagram showing the overall outline of the vehicle brake system of the first embodiment. FIG. 2 is a schematic cross-sectional view of a wheel brake mechanism for a rear wheel system provided in the vehicle brake device of the first embodiment. FIG. 3 is a schematic diagram showing deformation of the seal member in the electric brake device of the first embodiment. FIG. 4 is a flowchart showing processing executed by the brake control device of the first embodiment. FIG. 5 is a timing chart showing how the state changes over time in the comparative example, and a timing chart showing how the state changes over time in the first embodiment. FIG. 6 is a timing chart showing another state change over time in the first embodiment. FIG. 7 is a timing chart showing still another state change over time in the first embodiment. FIG. 8 is a flowchart showing processing executed by the brake control device of the second embodiment. FIG. 9 is a timing chart showing changes in state over time in the second embodiment.

Exemplary embodiments (first embodiment, second embodiment) of the present invention are disclosed below. The configurations of the embodiments shown below and the actions and results (effects) brought about by the configurations are examples. The present invention can be realized by configurations other than those disclosed in the following embodiments. Moreover, according to the present invention, at least one of various effects (including derivative effects) obtained by the following configuration can be obtained.

(First embodiment)
In the first embodiment, a vehicle brake system in which a disc brake type EPB is applied to the rear wheel system will be described as an example. FIG. 1 is a schematic diagram showing the overall outline of the vehicle brake system of the first embodiment. FIG. 2 is a schematic cross-sectional view of a wheel brake mechanism for a rear wheel system provided in the vehicle brake device of the first embodiment.

As shown in FIG. 1, the vehicle brake system of the first embodiment includes a service brake 1 that generates a service brake force (hydraulic pressure brake force) based on the pedaling force of the driver, and a EPB2 for regulating movement of vehicles.

The service brake 1 is a hydraulic brake mechanism (hereinafter also referred to as "hydraulic brake device") that generates brake fluid pressure based on the depression of the brake pedal 3 by the driver, and generates service braking force based on this brake fluid pressure. ). The hydraulic brake device is controlled by the ESC-ECU 8 (control section).

Specifically, the service brake 1 boosts the depression force corresponding to the depression of the brake pedal 3 by the driver with the booster 4, and then applies the brake fluid pressure corresponding to the boosted depression force to the master cylinder ( hereinafter referred to as M/C). This brake fluid pressure is transmitted to a wheel cylinder (hereinafter referred to as W/C) 6 provided in the wheel brake mechanism of each wheel to generate a service brake force. Further, an actuator 7 for brake hydraulic pressure control is provided between the M/C 5 and the W/C 6 . The actuator 7 adjusts the service brake force generated by the service brake 1 and performs various controls (for example, anti-skid control, etc.) for improving the safety of the vehicle.

Various controls using the actuator 7 are executed by an ESC (Electronic Stability Control)-ECU 8 that controls the service braking force. For example, the ESC-ECU 8 outputs a control current for controlling various control valves and pump driving motors provided in the actuator 7, thereby controlling the hydraulic circuit provided in the actuator 7 and transmitting it to the W/C 6. Controls the W/C pressure applied. As a result, wheel slip is avoided and the safety of the vehicle is improved. For example, the actuator 7 performs pressure increase control to control the application of the brake fluid pressure generated in the M/C 5 or the brake fluid pressure generated by driving the pump to the W/C 6 for each wheel. It is equipped with a valve and a pressure reduction control valve that reduces the W/C pressure by supplying the brake fluid in each W/C 6 to the reservoir. ing. In addition, the actuator 7 can realize the automatic pressurization function of the service brake 1, and automatically presses the W/C 6 even when the brake is not operated based on the control of the pump drive and various control valves. can be pressured.

On the other hand, the EPB 2 generates electric braking force by driving the wheel brake mechanism with the EPB motor 10, and is configured with an EPB-ECU 9 (control unit) for controlling the driving of the EPB motor 10. . Note that the EPB-ECU 9 and the ESC-ECU 8 transmit and receive information through CAN (Controller Area Network) communication, for example.

The wheel brake mechanism is a mechanical structure that generates braking force in the vehicle brake device of the first embodiment. The wheel brake mechanism of the front wheel system is configured to generate a service brake force by operating the service brake 1 . Further, the wheel brake mechanism of the rear wheel system has a common structure that generates braking force for both the operation of the service brake 1 and the operation of the EPB 2 . The wheel brake mechanism for the front wheel system is a wheel brake mechanism that has been generally used since the past without a mechanism that generates an electric braking force based on the operation of the EPB 2 with respect to the wheel brake mechanism for the rear wheel system. , the description is omitted here, and the wheel brake mechanism for the rear wheel system will be described below.

In the wheel brake mechanism of the rear wheel system, not only when the service brake 1 is actuated but also when the EPB 2 is actuated, the brake pad 11, which is a friction material shown in FIG. By sandwiching the brake discs 12 (12RL, 12RR, 12FR, 12FL) which are materials, a frictional force is generated between the brake pads 11 and the brake discs 12 to generate a braking force.

Specifically, the wheel brake mechanism rotates the EPB motor 10 which is directly fixed to the body 14 of the W/C 6 for pressing the brake pads 11 as shown in FIG. 2 in the caliper 13 shown in FIG. A spur gear 15 provided on the drive shaft 10a of the EPB motor 10 is rotated by rotating the drive shaft 10a. By transmitting the rotational force (output) of the EPB motor 10 to the spur gear 16 meshing with the spur gear 15, the brake pad 11 is moved and the EPB 2 generates electric braking force.

In addition to the W/C 6 and the brake pads 11 , the caliper 13 accommodates part of the end face of the brake disc 12 so as to be sandwiched between the brake pads 11 . The W/C 6 introduces brake fluid pressure into the hollow portion 14a of the cylindrical body 14 through the passage 14b, thereby generating W/C pressure in the hollow portion 14a, which is the brake fluid storage chamber. A rotary shaft 17, a propulsion shaft 18, a piston 19 and the like are provided in the hollow portion 14a.

One end of the rotating shaft 17 is connected to the spur gear 16 through an insertion hole 14c formed in the body 14, and when the spur gear 16 is rotated, the spur gear 16 is rotated. A male thread groove 17 a is formed in the outer peripheral surface of the rotating shaft 17 at the end opposite to the end connected to the spur gear 16 in the rotating shaft 17 . On the other hand, the other end of the rotating shaft 17 is supported by being inserted into the insertion hole 14c. Specifically, the insertion hole 14c is provided with an O-ring 20 and a bearing 21. The O-ring 20 prevents the brake fluid from leaking out through the space between the rotating shaft 17 and the inner wall surface of the insertion hole 14c. The other end of the rotary shaft 17 is supported by the bearing 21 while being held.

The propulsion shaft 18 is composed of a nut made up of a hollow cylindrical member, and has a female screw groove 18a formed in its inner wall surface to be screwed with the male screw groove 17a of the rotating shaft 17 . The propulsion shaft 18 is configured, for example, in a columnar or polygonal columnar shape provided with a key for preventing rotation, so that even if the rotating shaft 17 rotates, it is rotated around the center of rotation of the rotating shaft 17. There is no structure. Therefore, when the rotary shaft 17 is rotated, the engagement between the male thread groove 17a and the female thread groove 18a converts the rotational force of the rotary shaft 17 into a force that moves the propeller shaft 18 in the axial direction of the rotary shaft 17. Convert. When the driving of the EPB motor 10 is stopped, the propulsion shaft 18 stops at the same position due to the frictional force generated by the meshing of the male thread groove 17a and the female thread groove 18a. If the driving of the EPB motor 10 is stopped when this occurs, the propulsion shaft 18 is held at that position, and a desired electric braking force is maintained so that self-locking (hereinafter simply referred to as "locking") can be performed. there is

The piston 19 is arranged so as to surround the outer periphery of the propulsion shaft 18, and is constructed of a bottomed cylindrical member or polygonal cylindrical member, the outer peripheral surface of which is in contact with the inner wall surface of the hollow portion 14a formed in the body 14. are arranged as A seal member 22 is provided on the inner wall surface of the body 14 to prevent brake fluid leakage between the outer peripheral surface of the piston 19 and the inner wall surface of the body 14, and a structure that can apply W/C pressure to the end surface of the piston 19. It is said that The seal member 22 is used to generate a reaction force for pulling back the piston 19 during release control after lock control. Since the seal member 22 is provided, basically even if the brake pad 11 and the piston 19 are pushed by the inclined brake disc 12 during turning within a range that does not exceed the elastic deformation amount of the seal member 22, they are braked. By pushing back toward the disc 12 side, the clearance between the brake disc 12 and the brake pad 11 can be maintained with a predetermined clearance.

If the propulsion shaft 18 is provided with a key for preventing rotation, the key slides so that the piston 19 is not rotated around the rotation center of the rotation shaft 17 even if the rotation shaft 17 rotates. When the propelling shaft 18 has a polygonal prism shape, it has a polygonal cylindrical shape corresponding to it.

The brake pad 11 is arranged at the tip of the piston 19, and the brake pad 11 is moved in the left-right direction of the drawing as the piston 19 moves. Specifically, the piston 19 is movable in the left direction of the drawing as the propulsion shaft 18 moves, and the end of the piston 19 (the end opposite to the end where the brake pad 11 is arranged) By applying the W/C pressure, it is configured to be movable in the left direction on the paper surface independently of the propulsion shaft 18 .

Here, how the seal member 22 is deformed will be described with reference to FIG. FIG. 3 is a schematic diagram (a diagram showing only the seal member 22 extracted from the region R in FIG. 2) showing how the seal member 22 is deformed in the electric brake device of the first embodiment.

As shown in FIG. 3, when the brake is not applied, the seal member 22 is contained within the space without gaps. Further, during hydraulic braking, the seal member 22 is largely elastically deformed by being pushed by the brake fluid. If the seal member 22 is largely elastically deformed in this manner, the piston 19 can be moved to an appropriate release position by utilizing the force that causes the seal member 22 to return to its original shape when the EPB is released. can.

Also, during electric braking, the seal member 22 is slightly elastically deformed due to friction with the piston 19 . However, since the elastic deformation of the seal member 22 is small, it is not possible to move the piston 19 to the appropriate release position by using the force of the seal member 22 returning to its original shape when the EPB is released.

Therefore, if the EPB is released in such a state, a so-called drag may occur. Drag refers to a phenomenon in which the brake pads 11 and the brake discs 12 come into contact with each other during non-braking to generate a braking force.

If drag occurs, there will be demerits in various aspects such as fuel consumption, noise, and feeling of being stuck. In the prior art, in order to prevent drag from occurring when the EPB is released, the driver performs an operation (for example, depressing the accelerator pedal) to make the vehicle run, and then applies hydraulic pressure to release the EPB. , there was a problem that responsiveness is not good. A technique for improving responsiveness while avoiding drag in the first embodiment will be described below.

Returning to FIG. 1, in the wheel brake mechanism configured as described above, when the service brake 1 is operated, the piston 19 is moved leftward on the page based on the W/C pressure generated thereby. As a result, the brake pad 11 is pressed against the brake disc 12 to generate a service braking force. Further, when the EPB 2 is operated, the EPB motor 10 is driven to rotate the spur gear 15, which in turn rotates the spur gear 16 and the rotating shaft 17, so that the male screw groove 17a and the female screw groove The propeller shaft 18 is moved toward the brake disc 12 (toward the left in the drawing) based on the meshing of the shaft 18a. As a result, the tip of the propulsion shaft 18 comes into contact with the bottom surface of the piston 19 and presses the piston 19, and the piston 19 is also moved in the same direction, thereby pressing the brake pad 11 against the brake disc 12 and generating an electric braking force. generate Therefore, it is possible to use a common wheel brake mechanism that generates braking force for both the operation of the service brake 1 and the operation of the EPB 2 .

The vehicle also includes an operation SW (Switch) 23 , a display lamp 24 , an in-vehicle sensor 25 , an in-vehicle camera 26 , a distance sensor 27 and a front camera 28 .

The operation SW 23 is means for the driver to perform various operations (eg, EPB start operation, EPB release operation, etc.), and is provided, for example, on an instrument panel (not shown) inside the vehicle.

The display lamp 24 is means for displaying in accordance with an instruction from the EPB-ECU 9, and is provided in, for example, an instrument panel.

The in-vehicle sensor 25 is a sensor for detecting a predetermined state inside the vehicle. The in-vehicle sensor 25 is, for example, a sensor that detects the degree of accelerator pedal opening, a sensor that detects the degree of brake pedal opening, a sensor that detects the presence or absence of steering wheel operation and the amount of operation, and a sensor that detects the posture of the driver. . The in-vehicle sensor 25 is, for example, a sensor that detects G (acceleration) in the longitudinal direction (traveling direction) of the vehicle, or a sensor that detects the M/C pressure in the M/C 5 . The in-vehicle sensor 25 is, for example, a sensor that detects the temperature of a wheel brake mechanism (for example, a brake disc), a sensor that detects the rotation speed of each wheel, a sensor that detects (detects) the current of the EPB motor 10, or the like. be. The in-vehicle sensor 25 sends to the EPB-ECU 9 the detected values and the calculation results based on the detected values.

The in-vehicle photographing camera 26 photographs the interior of the vehicle. The vehicle interior photographing camera 26 photographs the interior of the vehicle including the driver, for example.

The distance measuring sensor 27 measures the distance to the preceding vehicle using, for example, ultrasonic waves, infrared rays, or the like.

A forward photographing camera 28 photographs the front of the vehicle. The forward photographing camera 28 photographs forward including, for example, forward vehicles and forward traffic lights.

The EPB-ECU 9 is composed of a well-known microcomputer equipped with a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), I/O, etc., and executes programs stored in the ROM or the like. Electric brake control is performed by controlling the rotation of the EPB motor 10 .

The EPB-ECU 9 inputs, for example, a signal or the like according to the operation state of the operation SW 23 and drives the EPB motor 10 according to the operation state of the operation SW 23 . Further, the EPB-ECU 9 executes lock control, release control, etc., based on the current detection value of the EPB motor 10. Based on the control state, the EPB-ECU 9 indicates that the lock control is being performed, and that the wheels are locked by the lock control. and that the wheel is in the released state (EPB released state) due to release control or release control. Then, the EPB-ECU 9 outputs a signal to the display lamp 24 to perform various displays.

In the vehicle brake system configured as described above, basically, the service brake 1 generates service braking force when the vehicle is running, thereby generating braking force on the vehicle. Further, when the vehicle is stopped (temporarily stopped, etc.) by the service brake 1, the driver presses the operation SW 23 to operate the EPB 2 to generate electric braking force, thereby stopping the vehicle (temporarily stopped, etc.). The operation of maintaining the electric braking force and then releasing the electric braking force is performed. That is, as the operation of the service brake 1, when the driver operates the brake pedal 3 while the vehicle is running, the brake hydraulic pressure generated in the M/C 5 is transmitted to the W/C 6, thereby generating service braking force. . The EPB 2 operates by driving the EPB motor 10 to move the piston 19 and pressing the brake pad 11 against the brake disc 12 to generate an electric braking force to lock the wheels, and the brake pad 11 is separated from the brake disk 12, the electric braking force is released and the wheels are released.

Specifically, the electric braking force is generated and released by lock/release control. In the lock control, the EPB motor 10 is rotated forward to operate the EPB 2, and the rotation of the EPB motor 10 is stopped at a position where the EPB 2 can generate a desired electric braking force, and this state is maintained. Thereby, a desired electric braking force is generated. In the release control, the EPB motor 10 is reversely rotated to operate the EPB 2 and release the electric braking force generated by the EPB 2 .

Details of the control of the ESC-ECU 8 and the EPB-ECU 9 will now be described. The ESC-ECU 8 and EPB-ECU 9 press the brake pad 11 (braking member) with hydraulic pressure toward the brake disc 12 (braking member) that rotates integrally with the wheel of the vehicle to generate hydraulic braking force. and an electric brake device that presses the brake pad 11 toward the brake disc 12 by driving the EPB motor 10 to generate an electric braking force.

The ESC-ECU 8 also executes hydraulic pressure control by the hydraulic brake device. The EPB-ECU 9 also executes lock control for generating an electric braking force by the electric brake device and release control for releasing the electric braking force.

In the locked state where the lock control is completed, the EPB-ECU 9 executes release preparation control for generating a predetermined hydraulic pressure by the hydraulic brake device when a preset release prediction condition is satisfied. When the set release start condition is satisfied, release control is executed. The release preparation control is executed by the EPB-ECU 9 instructing the ESC-ECU 8, for example.

Specifically, the EPB-ECU 9 determines whether or not the release prediction condition is satisfied based on at least one of predetermined information inside the vehicle and predetermined information outside the vehicle. In that case, the predetermined information in the vehicle is, for example, at least one of accelerator pedal opening, brake pedal opening, steering wheel operation, and driver's posture.

Further, the predetermined information outside the vehicle is at least one of information on a traffic light ahead (color information, etc.) and starting behavior of a vehicle ahead (vehicle forward, brake lamp off, etc.). The predetermined information inside the vehicle and the predetermined information outside the vehicle are, for example, information obtained by the in-vehicle sensor 25, the in-vehicle photographing camera 26, the range sensor 27, the front photographing camera 28, etc., or the information obtained by arithmetic processing of such information. It is information that can be obtained by

More specifically, for example, the EPB-ECU 9 determines that the release prediction condition is satisfied when the accelerator pedal opening is greater than zero and equal to or less than a weak first accelerator pedal opening threshold.

Further, for example, the EPB-ECU 9 determines that the release prediction condition is satisfied when the brake pedal opening changes from a state equal to or greater than a predetermined brake pedal opening threshold to a state less than the threshold.

Also, for example, the EPB-ECU 9 determines that the release prediction condition is satisfied when the driver touches the steering wheel.

Also, for example, the EPB-ECU 9 determines that the release prediction condition is satisfied when the posture (line of sight, posture, etc.) of the driver becomes the posture for driving.

Also, for example, the EPB-ECU 9 determines that the release prediction condition is satisfied when the color of the forward traffic light changes from red to blue.

Also, for example, the EPB-ECU 9 determines that the release prediction condition is satisfied when the forward vehicle starts moving forward.

Also, for example, the EPB-ECU 9 determines that the release prediction condition is satisfied when the brake lights of the preceding vehicle are extinguished.

Further, the EPB-ECU 9 determines whether or not the release start condition is satisfied based on at least one of the accelerator pedal opening, the electric brake release operation, and the starting behavior of the preceding vehicle.

More specifically, for example, the EPB-ECU 9 starts releasing when the accelerator pedal opening becomes equal to or greater than a second accelerator pedal opening threshold that is set to be larger than the first accelerator pedal opening threshold. Determine that the conditions are satisfied.

Further, for example, the EPB-ECU 9 determines that the release start condition is satisfied when the electric brake release operation is performed using the operation SW23.

Further, for example, the EPB-ECU 9 detects when the forward vehicle moves forward and is separated from the own vehicle by a predetermined distance or more, when the forward speed of the forward vehicle exceeds a predetermined speed, or when the brake lamp of the forward vehicle is turned off. , it is determined that the release start condition is satisfied.

Next, with reference to FIG. 4, processing executed by the brake control device of the first embodiment will be described. FIG. 4 is a flowchart showing processing executed by the brake control device of the first embodiment.

For example, when the vehicle is temporarily stopped while waiting for a signal, the driver first depresses the brake pedal to apply the hydraulic brake, and then performs the EPB start operation to apply the electric brake while the vehicle is stopped. In that case, the EPB-ECU 9 executes lock control in step S1.

Next, in step S2, the EPB-ECU 9 determines whether or not the release prediction condition is satisfied. If Yes, the process proceeds to step S3, and if No, the process returns to step S2. For example, when the driver puts his/her foot lightly on the accelerator pedal in preparation for starting the vehicle, in step S2, the EPB-ECU 9 determines that the accelerator pedal opening is greater than zero and less than or equal to the weak first accelerator pedal opening threshold. is detected, and it is determined that the release prediction condition is satisfied.

In step S3, the EPB-ECU 9 executes release preparation control. Specifically, the EPB-ECU 9 generates a predetermined hydraulic pressure with a hydraulic brake device. Thereby, the seal member 22 is largely elastically deformed (see FIG. 3).

Next, in step S4, the EPB-ECU 9 determines whether or not the release start condition is satisfied. If Yes, the process proceeds to step S5, and if No, the process returns to step S4. For example, when the driver depresses the accelerator pedal to start moving, in step S4, the EPB-ECU 9 detects that the accelerator pedal opening is greater than or equal to the second accelerator pedal opening threshold, and the release start condition is determined to be satisfied.

In step S5, the EPB-ECU 9 executes release control. Next, in step S6, the EPB-ECU 9 depressurizes (releases the hydraulic pressure). After that, vehicle running control is performed, and the vehicle starts running.

Here, FIG. 5 is a timing chart showing how the state changes over time in a comparative example (conventional technology), and a timing chart showing how the state changes over time in the first embodiment.

In the case of the comparative example, since the hydraulic pressure is increased after the release start condition is satisfied (time t2), there is a time lag from the establishment of the release start condition (time t2) to the start of release control (time t5). Further, pressure release is started at time t7 when the release control is completed, and pressure release is completed at time t8. Therefore, the time T1 (time t2 to t8) from the establishment of the release start condition to the completion of pressure release after the release control is long.

On the other hand, in the case of the first embodiment, first, when the release prediction condition is established (time t1), the hydraulic pressure is increased. Therefore, after that, when the release start condition is satisfied while the release prediction condition is ON (time t2), the hydraulic pressure has sufficiently increased, and the release control can be performed immediately (time t2 to t4). can. At time t3, the release start condition is OFF, so the release prediction condition is OFF. Further, pressure release is started at time t4 when the release control is completed, and pressure release is completed at time t6. Therefore, the time T2 (time t2 to t6) from the establishment of the release start condition to the completion of pressure release after the release control is significantly shorter than the time T1 in the case of the comparative example.

As described above, according to the brake control device of the first embodiment, the release preparation control for generating the predetermined hydraulic pressure when the release prediction condition is satisfied regarding the vehicle in which the electric brake is locked due to a temporary stop or the like. is executed, the release control can be completed quickly (significantly earlier than the conventional technology) when the driver subsequently performs an operation for causing the vehicle to run.

Note that if the release start condition is satisfied while the release preparation control is being executed, two methods, a first method and a second method, are possible. The first method waits until release preparation control is completed before starting release control.

FIG. 6 is a timing chart showing how the state changes over time in the first method. In the case of the first method, when the release prediction condition is satisfied (time t11) and the release start condition is satisfied while the hydraulic pressure is increasing (time t12), the release control is performed from time t14 when the hydraulic pressure increase is completed. to start. At time t13, the release start condition is OFF, so the release prediction condition is OFF. Further, pressure release is started at time t15 when release control is completed, and pressure release is completed at time t16.

Also in this case, the time T3 (time t12 to t16) from the establishment of the release start condition to the completion of pressure release after the release control is significantly shorter than the time T1 in the comparative example. In addition, by starting the release control after the hydraulic pressure rise is completed, the seal member 22 can be sufficiently elastically deformed, and dragging can be avoided more reliably.

In the second method, the EPB-ECU 9 forcibly starts release control when the release start condition is satisfied while the release preparation control is being executed.

FIG. 7 is a timing chart showing how the state changes over time in the second method. In the case of the second method, when the release prediction condition is satisfied (time t11) and the release start condition is satisfied while the hydraulic pressure is increasing (time t12), release control is performed from time t12 during the increase of the hydraulic pressure. to start. At time t13, the release start condition is OFF, so the release prediction condition is OFF. Further, pressure release is started at time t21 when release control is completed, and pressure release is completed at time t22.

In this case as well, the time T4 (time t12 to t22) from the establishment of the release start condition to the completion of pressure release after the release control is significantly shorter than the time T1 in the case of the comparative example. is shorter than the time T3, the responsiveness can be further improved. In addition, although the release control is started while the hydraulic pressure is in the middle of increasing, the possibility of the occurrence of drag can be greatly reduced compared to when the release control is started in a state where there is no hydraulic pressure.

(Second embodiment)
Next, the brake control device of the second embodiment will be explained. Descriptions of items similar to those of the first embodiment will be omitted as appropriate. In the brake control device of the second embodiment, the EPB-ECU 9 cancels the release preparation control if the release start condition is not satisfied within a predetermined time after executing the release preparation control.

FIG. 8 is a flowchart showing processing executed by the brake control device of the second embodiment. Descriptions of items similar to those in FIG. 4 will be omitted as appropriate. In step S1, the EPB-ECU 9 executes lock control.

Next, in step S2, the EPB-ECU 9 determines whether or not the release prediction condition is satisfied. If Yes, the process proceeds to step S3, and if No, the process returns to step S2.

In step S3, the EPB-ECU 9 executes release preparation control.

Next, in step S11, the EPB-ECU 9 determines whether or not a predetermined period of time has passed since the execution of the release preparation control.

In step S12, the EPB-ECU 9 cancels the release preparation control (releases the pressure) and returns to step S2.

In step S4, the EPB-ECU 9 determines whether or not the release start condition is satisfied. If Yes, the process proceeds to step S5, and if No, the process returns to step S11.

In step S5, the EPB-ECU 9 executes release control. Next, in step S6, the EPB-ECU 9 depressurizes. After that, vehicle running control is performed, and the vehicle starts running.

FIG. 9 is a timing chart showing changes in state over time in the second embodiment. When the release prediction condition is satisfied (time t31), the hydraulic pressure is increased. After that, at time t32 when a predetermined time has elapsed, the EPB-ECU 9 cancels the release preparation control and starts pressure release, and the pressure release is completed at time t33.

As described above, according to the brake control device of the second embodiment, when the release start condition is not satisfied within a predetermined time after executing the release preparation control, the caliper 13 and the like are released by canceling the release preparation control. It is possible to reduce the load on each device and contribute to prolonging the life of each device.

Although the embodiments and modifications of the present invention have been described above, the embodiments and modifications described above are merely examples, and are not intended to limit the scope of the invention. The novel embodiments and modifications described above can be implemented in various forms, and various omissions, replacements, or modifications can be made without departing from the spirit of the invention. Moreover, the embodiments and modifications described above are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and equivalents thereof.

For example, in the above-described embodiment, the rear wheels are electrically braked wheels, but the present invention is not limited to this, and the front wheels may be electrically braked wheels. Also, although the electric brake release operation is executed based on the operation SW for activating/releasing the EPB, it is not limited to this, and is for activating/releasing automatic driving control (for example, preceding vehicle following control). It may be executed based on an operation SW capable of detecting the driver's intention to start, such as the operation SW of .

DESCRIPTION OF SYMBOLS 1... Service brake (hydraulic pressure brake device), 2... EPB (electric brake device), 5... M/C, 6... W/C, 7... Actuator, 8... ESC-ECU (control part), 9... EPB- ECU (control unit) 10 EPB motor 11 brake pad 12 brake disc 13 caliper 14 body 14 a hollow portion 14 b passage 17 rotating shaft 17 a male screw groove 18 Propulsion shaft 18a Female thread groove 19 Piston 23 Operation switch 24 Indicator lamp 25 In-vehicle sensor 26 In-vehicle camera 27 Ranging sensor 28 Front camera.

Claims (4)

A hydraulic brake device that presses a braking member with hydraulic pressure toward a member to be braked that rotates integrally with a vehicle wheel to generate a hydraulic braking force;
an electric braking device that presses the braking member toward the member to be braked by driving a motor to generate an electric braking force;
A brake control device applied to a vehicle comprising
The brake control device includes a control unit that executes hydraulic pressure control by the hydraulic brake device, lock control for generating the electric braking force by the electric braking device, and release control for releasing the electric braking force. have
The control unit executes release preparation control for generating a predetermined hydraulic pressure by the hydraulic brake device when a preset release prediction condition is satisfied in a locked state in which the lock control is completed, and then performs a release preparation control in advance. When the set release start condition is satisfied, execute the release control ,
Determining whether or not the release prediction condition is satisfied based on at least one of the steering wheel operation, the driver's posture, the information of the front traffic light, and the starting behavior of the vehicle ahead,
When the driver touches the steering wheel, when the driver's posture changes to the driving posture, when the color of the traffic light ahead changes from red to blue, when the forward vehicle starts moving forward, and when the forward vehicle starts moving forward. Determining that the release prediction condition is satisfied when at least one of when the vehicle's brake lights are turned off,
brake controller. The control unit determines whether or not the release start condition is satisfied based on the starting behavior of the preceding vehicle,
At least one of when the forward vehicle moves forward and is separated from the own vehicle by a predetermined distance or more, when the forward speed of the forward vehicle reaches or exceeds a predetermined speed, or when the brake lamp of the forward vehicle is extinguished. If one is satisfied, determine that the release start condition is satisfied;
The brake control device according to claim 1 . 3. The brake control device according to claim 1, wherein said control unit cancels said release preparation control when said release start condition is not satisfied within a predetermined time after executing said release preparation control. . The brake according to any one of claims 1 to 3 , wherein the control unit forcibly starts the release control when the release start condition is satisfied while the release preparation control is being executed. Control device.

Images