JP2008143271A - Braking force control device and braking force control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device and a method for controlling the braking force capable of ensuring the durability of a brake shoe even when a vehicle is moved when a drum-in type parking brake is in a braked state. <P>SOLUTION: The braking force control device 10 of a service brake 30 in which the braking force is increased/decreased according to the step-in operation of a brake pedal 11 comprises an actuator 15 for reducing the braking force of a service brake 30, and a control means 21a for controlling the actuator 15 at the braking force reducing rate lower than the value at which the braking force is reduced when the parking brake 11 is not in a braked state while a parking brake 20 is in a braked state. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a braking force control device and a braking force control method for controlling a braking force of a vehicle, and more particularly to a braking force control device and a braking force control method capable of reducing the braking force by an actuator.

  FIG. 1 is a schematic plan view of a conventional parking brake device. The parking brake device of FIG. 1 is a drum-in type parking brake device provided on the left and right rear wheels of a vehicle. A drum 100 and a pair of brake shoes 110 and 150 that are rotatably supported inside the drum 100 are provided. The free end of the brake shoe 150 is connected to one end of a brake lever 170 that is rotatable about a support pin 210, the spring 140 is connected to the other end of the brake lever 170, and the other end of the spring 140 is connected to the other end of the spring 140. A wire 130 drawn out of the drum 100 is connected. The support pin 210 side of the brake lever 170 is bridged with the brake shoe 110 via a spring 180 and a strut 190.

  When tension is applied to the wire 130, the brake lever 170 rotates clockwise about the support pin 210. Accordingly, the brake shoe 110 is pushed to the left by the brake lever 170 via the strut 190, and the lining 120 of the brake shoe 110 is pushed against the inner peripheral surface of the drum 100. Further, the free end of the brake shoe 150 moves to the right with the strut 190 as a fulcrum, and accordingly, the lining 160 of the brake shoe 150 is pressed against the inner peripheral surface of the drum 100. When tension is applied to the wire 130 in this manner, the pair of brake shoes 110 and 150 are in a widened braking state, and when the wheel tries to rotate, the brake shoes 110 or 150 abut against the anchor 200 and generate braking torque.

If the vehicle is moved in a braking state, the linings 120 and 160 are worn, and this may cause a brake noise during traveling. Therefore, a brake device that prevents forgetting to release the parking brake device has been proposed (see, for example, Patent Document 1). The brake device described in Patent Document 1 performs control so as not to release a service brake by hydraulic pressure acting for stopping the vehicle when an accelerator operation is performed when the parking brake device is in a braking state. Accordingly, even if the driver operates the accelerator, the vehicle is prevented from starting, so the driver can be informed that the parking brake device has been forgotten to be released.
JP-A-5-85318

  However, the brake device described in Patent Document 1 prevents dragging of the parking brake when the vehicle starts, and does not consider the action that can occur in the parking brake device when the vehicle is stopped. For this reason, when a wheel rotates during a stop, there exists a problem that the brake shoe 110 or 150 may contact | abut to the anchor 200 strongly, and there exists a possibility that the brake shoe 110 or 150 may deform | transform. If the brake shoe 110 or 150 is deformed, it will affect the durability, for example, the braking force will be reduced, and it will also make an abnormal noise in contact with the drum surface. Although it is conceivable to increase the strength of the brake shoe 110 or 150, it is not preferable because it increases cost and weight.

  In view of the above problems, an object of the present invention is to provide a braking force control device that ensures the durability of a brake shoe even when the vehicle moves when the drum-in type parking brake device is in a braking state.

  In view of the above problems, the present invention provides an actuator for reducing the braking force of a service brake (for example, the hydraulic pressure of the hydraulic brake device 30) in a braking force control device for a service brake in which the braking force increases or decreases in response to a depression operation of a brake pedal. When the parking brake is in a braking state, the control means (for example, ACT control means) controls the actuator at a braking force reduction speed (for example, a pressure-reduction gradient) slower than the speed at which the braking force decreases when the parking brake is not in the braking state. 21a).

  According to the present invention, when the parking brake device is in the braking state, the braking force is reduced more slowly than when the parking brake is not in the braking state. The acting shock can be reduced.

  In one embodiment of the present invention, the sensor has a sensor for detecting the magnitude of the braking force of the service brake, and the control means detects the magnitude of the braking force of the service brake when the parking brake is in a braking state, which is detected by the sensor. When the length is less than a predetermined value, the actuator is requested to increase the braking force of the service brake to a predetermined value or more.

  According to the present invention, by increasing the braking force when the magnitude of the braking force of the service brake is a predetermined value or less, it is possible to mitigate the impact acting on the brake shoe even when the inclination is large, and to prevent deformation of the brake shoe. Can increase opportunities to

  In one embodiment of the present invention, the braking force decrease speed is slower than the speed at which the braking force decreases when the depression force of the brake pedal is zero.

  According to the present invention, when the amount of operation of the brake pedal on the slope is zero, the impact acting on the brake shoe can be reduced by slowly reducing the braking force.

  It is possible to provide a braking force control device and a braking force control method that can ensure durability of the brake shoe even when the vehicle moves when the drum-in type parking brake device is in a braking state.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the accompanying drawings. When the parking brake device 20 is in a braking state, the braking force control device 10 according to the present embodiment gently lowers the hydraulic pressure of the hydraulic brake device so that the brake shoe and the anchor of the parking brake device 20 are brought into contact with each other slowly. The deformation is prevented.

  First, the parking brake device (hereinafter referred to as PKB device) 20 and the hydraulic brake device 30 will be briefly described. FIG. 2A is a schematic configuration diagram of the drum-in type PKB apparatus 20. The PKB device 20 has a pair of brake shoes 2a and 2b that can rotate inside the drum 1. The lining 5a is attached to the brake shoe 2a on the surface facing the drum 1, and the lining 5b is attached to the brake shoe 2b. It has been. One ends of the brake shoes 2a and 2b are connected to each other by an adjuster 4, and the other ends are connected to each other by an expanding unit 7 that expands the interval. Further, a return spring 3a is stretched over the adjuster 4 side of the brake shoes 2a, 2b, and a return spring 3b is spanned over the spreading unit 7 side.

  Before tension is applied to the wires 19R and 19L, the ends of the brake shoes 2a and 2b on the side of the spreading unit 7 are in contact with the anchor 6 by the urging force of the return springs 3a and 3b. When tension is applied to the wires 19R and 19L, the unfolding unit 7 unfolds the pair of brake shoes 2a and 2b according to the tension, so that the brake shoe 2a and the lining 5a are arranged on the left side of the drum, the brake shoe 2b and the lining. 5b is respectively pressed to the right side of the drum. As a result, the ends of the brake shoes 2a and 2b on the side of the spreading unit 7 are opened and a gap is formed between the brake shoes 2a and 2b. When the wheel tries to rotate, the brake shoe 2a or 2b comes into contact with the anchor 6 to generate a braking torque.

  FIG. 2B is a schematic cross-sectional view of the PKB device 20 and the hydraulic brake device 30 of the present embodiment. The hydraulic brake device 30 brakes the disc rotor 1a by pressing the disc rotor 1a integrally provided on the outer periphery of the drum 1 with hydraulic pressure. A disc brake caliper 32 is disposed so as to straddle the disc rotor 1a, and a pair of pads 33a and 33b respectively assembled to a piston 31 and a claw portion of the caliper 32 fitted to a cylinder portion of the caliper 32 are discs. It is provided facing the rotor 1a. When the hydraulic pressure is applied to the piston 31, both pads 33a and 33b press the disk rotor 1a from both sides to brake the rotation of the disk rotor 1a. The hydraulic brake device 30 may be a drum type or an electric type that drives the pads 33a and 33b by a motor.

  FIG. 3 shows a system configuration diagram of the braking force control apparatus 10. A hydraulic brake device 30 is disposed on the front wheels FL and FR, and a PKB device 20 and a hydraulic brake device 30 are disposed on the rear wheels RL and RR. Wires 19L and 19R connected to the spreading unit 7 of the PKB device 20 are connected to a parking brake actuator (hereinafter referred to as a PKB actuator) 18, and are operated by a driver's operation or control of the brake ECU 21 to operate the wires 19L and 19R. 19R is rolled up or released. The PKB actuator 18 converts the rotation of the motor into a linear driving force, and distributes it to the wires 19L and 19R by an equalizer while winding up the wires 19R and 19L until a predetermined tension is reached. Set to the braking state. The PKB actuator 18 may be a manual operation type in which a driver operates a parking lever to switch between braking and releasing.

  Further, the hydraulic pressure of the hydraulic brake device 30 for each wheel is increased or decreased by the operation of the brake pedal 11 and is controlled by the brake actuator 15 without the operation of the driver. The brake actuator 15 has various valve devices and pumps, and the hydraulic pressure can be independently controlled for each wheel by opening and closing the valve device controlled by the brake ECU 21, and the brake pedal by the driver is driven by driving the pump. The hydraulic pressure for braking each wheel can be obtained without the operation of 11.

  The configuration of the brake actuator 15 will be briefly described. Focusing on the hydraulic path to a predetermined wheel, a shut-off valve (normally open valve) is provided in the path from the master cylinder 12 to the hydraulic brake device 30, and when the driver's brake pedal 11 is depressed, the reservoir tank The hydraulic fluid 13 is compressed and hydraulic pressure corresponding to the pedaling force is applied to the hydraulic brake device 30. This shut-off valve is closed when the brake ECU 21 controls the hydraulic pressure, and shuts off the path from the master cylinder 12 to the hydraulic brake device 30.

  Further, a holding valve (normally open valve) is provided on the hydraulic brake device 30 side of the shutoff valve, and closing the holding valve closes the hydraulic system on the hydraulic brake device 30 side from the holding valve. can do. Further, a path connecting to the reservoir is branched in a path connecting the holding valve and the hydraulic brake device 30, and a pressure reducing valve (normally closed valve) is provided in the branched path.

  The discharge port of the pump is connected to a path between the shutoff valve and the holding valve. On the other hand, the suction port side of the pump is connected to a reservoir. Therefore, a pressure reducing valve and a reservoir are connected to the suction port side of the pump.

  From the above configuration, if the pump is driven with the shutoff valve and the pressure reducing valve closed and the holding valve opened, the hydraulic pressure generated by the pump is supplied to the hydraulic brake device 30, so that a desired braking force is applied to the wheels. be able to. When the driver operates the brake pedal 11 too strongly and the wheel is locked, the hydraulic brake device 30 is adjusted to an appropriate braking force by closing the shutoff valve and the holding valve and adjusting the opening of the pressure reducing valve. The braking force can be reduced. Since the brake actuator 15 has the hydraulic circuit as described above for each wheel, the hydraulic pressure can be independently controlled for each wheel.

  The brake ECU 21 receives the brake pedal operation information detected by the stop lamp switch when the brake pedal 11 is operated, the master cylinder hydraulic pressure information of the master cylinder 12 detected by the hydraulic sensor 14, and the tension of the wires 19L and R. The PKB operation information indicating whether or not the PKB device 20 is in a braking state, shift position information, accelerator opening information, and road surface inclination information detected by the inclination sensor 17 are input.

  The brake ECU 21 is a CPU that executes programs, a ROM that stores programs, a RAM that temporarily stores data and programs, an EEPROM (Electronically Erasable and Programmable Read Only Memory), an input / output interface that inputs and outputs data, and other ECUs A communication unit that communicates with the microcomputer is configured as a microcomputer connected via a bus. When the CPU executes the program, the ACT control unit 21a, the PKB control unit 21b, and the necessary hydraulic pressure extraction unit 21c are realized.

  In the present embodiment, the braking force control device 10 that controls the braking force of the hydraulic brake device 30 when the vehicle stops will be described. When the vehicle is stopped, the driver often operates the PKB device 20 while operating the brake pedal 11, and after the PKB device 20 is put into a braking state, the pedaling force of the brake pedal 11 is returned to zero. However, when the PKB device 20 is put into a braking state, the gap between the anchor 6 and the brake shoes 2a and 2b is generated as described above. Therefore, the brake shoes 2a and 2b and the anchor 6 are in strong contact with each other due to the rotation of the wheels due to gravity on the slope. This causes deformation of the brake shoes 2a and 2b. In the present embodiment, when the PKB device 20 is in a braking state, the brake ECU 21 gently reduces the hydraulic pressure of the hydraulic brake device 30 to bring the anchor 6 and the brake shoes 2a and 2b into contact with each other, thereby The deformation of 2a and 2b is prevented.

  FIG. 4 is a flowchart showing a control procedure of the braking force control apparatus 10. The control procedure of FIG. 4 starts when the vehicle speed is zero and the inclination detected by the inclination sensor 17 is greater than or equal to a predetermined value.

  First, the ACT control means 21a determines whether or not the brake pedal 11 is operated with a sufficient depression force by the driver (S1). The criterion for determining whether or not the pedal force is sufficient is whether or not the braking force necessary for stopping on the stopped slope is obtained by the hydraulic brake device 30. Whether the pedal effort is sufficient may be determined based on master cylinder hydraulic pressure information, or may be determined based on the hydraulic pressure (wheel cylinder pressure) of the hydraulic brake device 30.

  Whether or not the pedal force is sufficient is preferably variable according to the slope of the slope, but the necessary master cylinder hydraulic pressure may be a hydraulic pressure for stopping the slope on the maximum slope that can be assumed. When making it variable according to the slope, a map that defines the relationship between the inclination and the necessary master cylinder oil pressure is stored in advance in a ROM or the like, and the necessary oil pressure extracting means 21c extracts the master cylinder oil pressure from the map based on the inclination information. To do. Since the driving torque due to the inclination changes according to the gear ratio of the transmission, the necessary master cylinder hydraulic pressure may be corrected based on the shift position information. As a result, the necessary master cylinder hydraulic pressure can be calculated with high accuracy, and the opportunity to prevent the deformation of the brake shoes 2a, 2b can be increased.

  When the depressing force of the brake pedal 11 is not sufficient (No in S1), the ACT control means 21a controls the brake actuator 15 to add the insufficient hydraulic pressure to the hydraulic brake device 30 (S2). Thereby, even when the depression force of the brake pedal 11 is not sufficient, the opportunity to prevent the deformation of the brake shoes 2a and 2b can be increased. The wheels to which hydraulic pressure is added may be only the rear wheels RL and RR in which the PKB device 20 is disposed, or hydraulic pressure may be added to all four wheels. It should be noted that by adding an insufficient amount of hydraulic pressure according to the slope of the slope, when the slope is not so large, it is possible to prevent the extra hydraulic pressure from being applied and to perform additional control of the hydraulic pressure in a short time.

  When the depression force of the brake pedal 11 is sufficient (Yes in S1), the PKB control means 21b determines whether or not the PKB device 20 is in a braking state (S3). If it is not in a braking state (No in S3), it waits until the PKB device 20 is activated.

  When the PKB device 20 is in a braking state (Yes in S3), the vehicle can be stopped even if the braking force by the hydraulic brake device 30 is released, so the ACT control means 21a starts depressurization of the hydraulic brake device 30 (S4). By slowly performing this decompression, the deformation of the brake shoes 2a, 2b can be prevented. The speed of depressurization with respect to time (hereinafter referred to as a depressurization gradient) is sufficiently small. For example, even in the case of a slope with a maximum slope that can be assumed, the brake shoes 2a and 2b gradually approach the anchor 6 slowly. Reduce pressure. In addition, you may make a pressure reduction gradient small, so that inclination is large.

  The ACT control unit 21a determines whether or not a predetermined time has elapsed since the start of decompression (S5), and repeats this determination until the predetermined time has elapsed. This predetermined time is the time required for the brake shoes 2a, 2b to contact the anchor 6. If the depressurization gradient is constant, the smaller the slope of the slope, the longer it takes for the brake shoes 2a, 2b and the anchor 6 to come into contact with each other. It takes time to complete. However, the driver often operates the brake pedal 11 with the pedaling force corresponding to the inclination, and when the pedaling force is insufficient, the hydraulic pressure corresponding to the inclination is added, so that the predetermined time is constant regardless of the inclination. However, this predetermined time is not so long. That is, by reducing the pressure for a predetermined time with a pressure reducing gradient assuming the slope with the maximum slope, the impact on the brake shoe can be alleviated regardless of the addition of hydraulic pressure or the slope of the slope.

  In addition, you may detect contact | abutting of brake shoe 2a, 2b and the anchor 6 based on rotation of the wheel detected by the vehicle speed sensor.

  When the predetermined time has elapsed (Yes in S5), the ACT control unit 21a determines whether or not the brake pedal 11 is operated based on the brake pedal operation information (S6). When the driver is operating the brake pedal 11 (Yes in S6), the hydraulic pressure of the hydraulic brake device 30 is held at the hydraulic pressure when a predetermined time has elapsed. Since the brake shoes 2a, 2b and the anchor 6 are already in contact with each other, the hydraulic pressure of the hydraulic brake device 30 may be increased to the hydraulic pressure before decompression.

  When the driver does not operate the brake pedal 11 (No in S6), the ACT control means 21a completely depressurizes the hydraulic brake device 30 because the driver does not intend to brake by the hydraulic brake device 30 (S7). ).

  As described above, when the PKB device 20 is in a braking state, the brake shoes 2a and 2b can be prevented from being deformed by slowly reducing the pressure of the hydraulic brake device 30. 5A to 5C are views showing the hydraulic pressure of the hydraulic brake device 30 obtained by the control procedure of FIG. 4 together with the master cylinder hydraulic pressure and the tension of the PKB device 20 operated by the driver. The numbers I to IV indicate the correspondence between the time courses in FIGS. 5A to 5C and the steps in FIG.

[When the depressing force of the brake pedal 11 is sufficient]
I: FIG. 5A shows the hydraulic pressure of the hydraulic brake device 30 controlled by the braking force control device 10 when the driver's depression force of the brake pedal 11 is sufficient. The horizontal axis is time, and the vertical axis is hydraulic pressure. For example, assuming that the time when the driver stops by operating the brake pedal 11 is zero, the driver continues operating the brake pedal 11 with a sufficient pedal effort. If the vehicle stops and the inclination is equal to or greater than a predetermined value, it is determined whether or not the depression force of the brake pedal 11 is sufficient.
II: In FIG. 5 (a), the pedal force of the brake pedal 11 is sufficient to stop, so the PKB control means 21b determines whether the PKB device 20 is in a braking state.
III: Since the PKB device 20 is in a braking state, the ACT control unit 21a starts depressurization with a predetermined depressurization gradient. Therefore, the hydraulic pressure of the hydraulic brake device 30 gradually decreases from III to IV.
IV: When a predetermined time elapses, the ACT control means 21a completely reduces the hydraulic pressure of the hydraulic brake device 30 when the brake pedal 11 is not operated.

[When the pedal force of the brake pedal 11 is insufficient]
I: FIG. 5B shows the hydraulic pressure of the hydraulic brake device 30 controlled by the braking force control device 10 when the driver's depression force of the brake pedal 11 is insufficient. If the depressing force of the brake pedal 11 is insufficient, the brake shoes 2a and 2b may abruptly contact the anchor 6 when decompression is started.
II: The ACT control means 21 a controls the actuator 15 to add a hydraulic pressure corresponding to the inclination to the hydraulic brake device 30. Thereby, the hydraulic pressure of the hydraulic brake device 30 increases. Further, the PKB control means 21b determines whether or not the PKB device 20 is in a braking state.
III: Since the PKB device 20 is in a braking state in FIG. 5B, the ACT control means 21a starts depressurization with a predetermined depressurization gradient. Therefore, the hydraulic pressure of the hydraulic brake device 30 gradually decreases from III to IV.
IV: When a predetermined time elapses, the ACT control means 21a completely reduces the hydraulic pressure of the hydraulic brake device 30 when the brake pedal 11 is not operated.

[When the brake pedal 11 is not operated]
I: FIG. 5C shows the hydraulic pressure of the hydraulic brake device 30 controlled by the braking force control device 10 when the brake pedal 11 is not operated by the driver. Accordingly, FIG. 5C does not show the master cylinder hydraulic pressure indicating the driver's pedaling force. The case where the brake pedal 11 is not operated before the PKB device 20 is activated when the vehicle is stopped is, for example, the case where the foot is released from the brake pedal 11 immediately before the PKB device 20 is activated.
II: Since the fact that the brake pedal 11 is not operated is the same as the case where the brake pedal 11 is not operated with sufficient pedaling force, the ACT control means 21a controls the actuator 15 to add the hydraulic pressure corresponding to the inclination to the hydraulic brake device 30. To do. Thereby, the hydraulic pressure of the hydraulic brake device 30 increases. Further, the PKB control means 21b determines whether or not the PKB device 20 is in a braking state.
III: Since the PKB device 20 is in a braking state in FIG. 5C, the ACT control means 21a starts depressurization with a predetermined depressurization gradient. Therefore, the hydraulic pressure of the hydraulic brake device 30 gradually decreases from III to IV.
IV: When a predetermined time elapses, the ACT control means 21a completely reduces the hydraulic pressure of the hydraulic brake device 30 when the brake pedal 11 is not operated.

  Even when the driver suddenly releases the brake pedal 11 after stopping the vehicle on the slope and putting the PKB device 20 in the braking state, the braking force control device 10 of this embodiment gradually reduces the hydraulic pressure of the hydraulic brake device 30. By depressurizing the brake shoes 2a, the anchors 6 and the brake shoes 2a, 2b can be brought into contact with each other slowly to prevent the brake shoes 2a, 2b from being deformed. Since it is not necessary to increase the strength of the brake shoes 2a and 2b, there is no increase in cost and weight.

  In the present embodiment, a braking force control device 10 that controls the hydraulic pressure of the hydraulic brake device 30 and the tension of the PKB device 20 when starting the vehicle will be described. If the driver forgets to release the PKB device 20 that has been in the braking state at the time of parking, the brake shoes 2a, 2b and the anchor 6 come into strong contact with each other and the brake shoes 2a, 2b are deformed. In this embodiment, when starting the vehicle, at least one of the control of increasing the hydraulic pressure of the hydraulic brake device 30 or decreasing the tension of the PKB device 20 is performed, and the anchor 6 and the brake shoes 2a, 2b are controlled. Is prevented from deforming the brake shoes 2a, 2b.

  FIG. 6 is a flowchart showing a control procedure of the braking force control apparatus 10. The control procedure shown in FIG. 5 starts when, for example, the ignition is turned on.

  First, the PKB control means 21b determines whether or not the PKB device 20 is in a braking state based on the PKB operation information (S10).

  Next, the start operation detecting means 3d determines whether or not an operation for starting the vehicle is detected by the driver (S20). When the start operation is not detected (No in S20), the determination is repeated from Step S10. The start operation is, for example, an operation in which the driver sets the shift position to D (drive) or an operation to increase the accelerator opening by the accelerator pedal. If the shift position and the accelerator pedal operation are the conditions for the start operation, the start operation of the driver can be detected with high accuracy, and the operating frequency of the braking force control device 10 can be suppressed.

  When a start operation is detected (Yes in S20), the ACT control unit 21a controls the brake actuator 15 to increase the pressure of the hydraulic brake device 30, or the PKB control unit 21b controls the PKB actuator 18 to control the PKB device. At least one of the control of reducing the tension of 20 is performed (S30).

  Increasing the hydraulic pressure of the hydraulic brake device 30 makes it difficult for the vehicle to start even when the accelerator pedal is operated. Further, the PKB control means 21b reduces the tension of the PKB device 20, so that the brake shoes 2a and 2b are hardly dragged by the drum 1 even when the vehicle starts. Therefore, when both the increase of the hydraulic pressure of the hydraulic brake device 30 and the decrease of the tension of the PKB device 20 are controlled, the brake shoes 2a and 2b are not easily dragged by the drum 1 even if the vehicle starts by overcoming the hydraulic brake device 30. Therefore, the deformation of the brake shoes 2a and 2b can be further easily prevented. Note that all four wheels control the hydraulic pressure of the hydraulic brake device 30.

  Next, the start operation detecting means 3d determines again whether or not a start operation for starting the vehicle is detected by the driver (S40). When the start operation is continued (Yes in S40), the ACT control unit 21a maintains the hydraulic pressure of the hydraulic brake device 30, and the PKB control unit 21b continues to reduce the tension of the PKB device 20.

  When the start operation is not detected (No in S40), the PKB control means 21b returns the PKB device 20 to the original tension (S50).

  Then, the PKB control means 21b determines whether or not the tension of the PKB device 20 has been restored (S60), and when it returns to the original tension (Yes in S60), the ACT control means 21a controls the brake actuator 15. The hydraulic brake device 30 is returned to the original hydraulic pressure (S70). That is, if the brake can be stopped by the braking force of the PKB device 20, returning the hydraulic brake device 30 to the original hydraulic pressure leads to protection of the brake actuator 15 and can prevent a reduction in braking force.

  In this way, even if the driver forgets to release the PKB device 20 at the time of starting, the vehicle is difficult to start due to the braking force of the hydraulic brake device 30, and the brake shoes 2 a and 2 b are released due to the decrease in the tension of the PKB device 20. Since it becomes difficult to be dragged by the drum 1, it is possible to prevent the vehicle from running strongly while being in contact with the anchor or in contact with the anchor, and deformation of the brake shoes 2a and 2b can be prevented.

FIG. 7 is a view showing the hydraulic pressure of the hydraulic brake device 30 obtained by the control procedure of FIG. 6 together with the tension of the PKB device 20. The numbers I to III indicate the correspondence between the time course in FIG. 7 and the steps in FIG.
I: The PKB device 20 is in a braking state. By detecting the starting operation as it is, the ACT control means 21a controls the brake actuator 15 to increase the hydraulic pressure of each wheel, and the PKB control means 21b controls the PKB actuator 18 to reduce the tension.
II: While the start operation is detected, the PKB actuator 18 continues to reduce the tension, so the tension becomes zero when a long time elapses while the start operation is detected (indicated by a dotted line in FIG. 6). ) By reducing the tension without reducing the tension to zero, the brake shoes 2a and 2b are less likely to be dragged by the drum 1. Therefore, the deformation of the brake shoes 2a and 2b is prevented, and the response when restoring the tension is restored. Can be improved. When the start operation is no longer detected, the PKB control unit 21b holds the tension for a predetermined time (or immediately after the start operation is no longer detected), and then controls the PKB actuator 18 to restore the tension (increase in tension). ).
III: When the tension of the PKB device 20 is restored, the ACT control means 21a controls the brake actuator 15 to restore the hydraulic pressure of each wheel (decompression).

  As described above, the braking force control device 10 according to the present embodiment prevents the deformation of the brake shoes 2a and 2b even if the driver forgets to release the PKB device 20 that is in a braking state at the time of parking. be able to.

  As described above, the braking force control device 10 of the present embodiment can improve the durability of the brake shoes 2a and 2b even when the vehicle moves when the PKB device 20 is in a braking state.

It is a schematic plan view of a conventional parking brake device. It is a schematic block diagram of a parking brake device and a hydraulic brake device. It is a system configuration figure of a braking force control device. It is a flowchart figure which shows the control procedure of a braking force control apparatus. It is a figure which shows the oil_pressure | hydraulic of the hydraulic brake device obtained by the control procedure of FIG. 4 with the tension | tensile_strength of the master cylinder oil pressure by a driver | operator, and a PKB apparatus. It is a flowchart figure which shows the control procedure of the braking force control apparatus in Example 2. FIG. It is a figure which shows the oil_pressure | hydraulic of the hydraulic brake device obtained by the control procedure of FIG. 6 with the tension | tensile_strength of a PKB apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Drum 2a, 2b Brake shoe 3a, 3b Return spring 4 Adjuster 5a, 5b Lining 6 Anchor 7 Opening unit 10 Braking force control apparatus 11 Brake pedal 12 Master cylinder 13 Reservoir tank 14 Hydraulic sensor 15 Brake actuator 17 Inclination sensor 18 PKB actuator 19L, 19R Wire 20 Parking brake (PKB) device 21 Brake ECU
21a ACT control means 21b PKB control means 21c Necessary hydraulic pressure extraction means 30 Hydraulic brake device

Claims (4)

In a braking force control device for a service brake in which the braking force increases or decreases according to the depression operation of the brake pedal,
An actuator that reduces the braking force of the service brake;
Control means for controlling the actuator at a braking force decrease speed slower than a speed at which the braking force decreases when the parking brake is in a braking state;
A braking force control device comprising: It has a sensor that detects the magnitude of the braking force of the service brake,
The control means requests the actuator to increase the braking force of the service brake to a predetermined value or more when the parking brake is in a braking state or the magnitude of the braking force of the service brake when the parking brake is started is less than a predetermined value. To
The braking force control apparatus according to claim 1.   The braking force control device according to claim 1, wherein the braking force decrease speed is slower than a speed at which the braking force decreases when the depression force of the brake pedal is set to zero. In the service brake braking force control method in which the braking force increases or decreases according to the depression operation of the brake pedal,
A step in which the braking force control device determines whether or not the parking brake is in a braking state;
When the parking brake is in a braking state, controlling the actuator at a braking force reduction rate that is slower than the rate at which the braking force is reduced when the parking brake is not in a braking state;
A braking force control method comprising:

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