JP2021154769A - Electric parking brake control device - Google Patents

Abstract

To quickly give brake force to a vehicle when operating an electric parking brake during travel of the vehicle.SOLUTION: An electric parking brake control device executes: initial brake control (S21 to S22) for continuously supplying electric power to an electric actuator until a current monitoring part detects a second current larger than a first current when a friction member starts to contact a rotor in the case that instruction for operating an electric parking brake is inputted during travel of a vehicle; temporary stop control (S31 to S34) for stopping supply of electric power to the electric actuator for a prescribed time when the current monitoring part detects a current that is equal to or more than the second current; and step-up control (S41 to S54) for gradually increasing control force given to the friction member by repeatedly supplying and stopping electric power to the electric actuator after temporary stop control.SELECTED DRAWING: Figure 5

Description

The present invention relates to an electric parking brake control device that controls drive and stop of an electric actuator that operates a parking brake mechanism.

Conventionally, as an electric parking brake control device, when applying control for applying a braking force while a vehicle is running, the electric motor is continuously energized until the start of contact between the braking member and the braked member is detected, and the braking member and the braking member It is known that when the start of contact with the braked member is detected, the electric motor is repeatedly operated and stopped to perform step-up control for stepwise increasing the clamping force of the braking member on the braked member.

Japanese Patent No. 6392895

However, in the prior art, when the apply control is performed while the vehicle is running, when the contact between the braking member and the braked member is detected, the electric motor is stopped, so that the braking force cannot be quickly applied to the vehicle. was there.

Therefore, an object of the present invention is to promptly apply a braking force to the vehicle when the electric parking brake is operated while the vehicle is running.

In order to solve the above problems, the electric parking brake control device according to the present invention rotates a rotating body that rotates integrally with the wheel, a friction member that generates a braking force on the wheel when pressed against the rotating body, and a friction member. An electric parking brake control device that controls a parking brake device including an electric actuator that gives an operating force to move the wheel in a direction of pressing against the body, and includes a current monitoring unit that monitors the current of the electric actuator.
In the electric parking brake control device, when an instruction to operate the electric parking brake is input while the vehicle is running, the current monitoring unit has a second current larger than the first current when the friction member starts to come into contact with the rotating body. Initial braking control that continuously supplies power to the electric actuator until a current is detected, and temporary stop control that stops power supply to the electric actuator for a predetermined time when the current monitoring unit detects a current equal to or higher than the second current. After the stop control, the electric actuator is repeatedly supplied with power and stopped to gradually increase the operating force, and the step-up control is executed.

According to such a configuration, when an instruction to operate the electric parking brake is input while the vehicle is running, the current monitoring unit has a higher current than the first current when the friction member starts to come into contact with the rotating body. Since the initial braking control that continuously supplies power to the electric actuator is executed until the two currents are detected, a large braking force can be generated at the initial stage of starting the operation of the electric parking brake, and the braking force can be promptly applied to the vehicle. can.

It is desirable that the second current is a current corresponding to an operating force that is smaller than the braking force at which at least one wheel starts to slip.

According to such a configuration, the wheels of the vehicle are less likely to slip, so that the behavior of the vehicle can be stabilized.

It is desirable that the operating force to be increased in the above-mentioned initial braking control is larger than the operating force to be increased by operating the electric actuator once in the step-up control.

According to such a configuration, the braking force can be applied to the vehicle more quickly.

According to the present invention, a large braking force can be generated at the initial stage of starting the operation of the electric parking brake, and the braking force can be quickly applied to the vehicle.

It is a block diagram of the vehicle provided with the brake fluid pressure control device for a vehicle which concerns on embodiment of this invention. It is a figure which shows the drum brake and the parking brake mechanism, and is the figure (a) which shows the state which the brake is not applied, and the figure (b) which shows the state which the brake is applied by the parking brake mechanism. It is sectional drawing which shows the electric actuator of a parking brake mechanism. It is a block diagram of a control part. It is a flowchart which shows the process in the case of applying control of an electric parking brake during traveling. It is a timing chart when there is an apply request during running.

Next, an embodiment of the present invention will be described in detail with reference to the drawings as appropriate.
As shown in FIG. 1, the vehicle CR includes a drum brake D, a parking brake mechanism 200, and a vehicle brake fluid pressure control device 100.

Drum brakes D are provided on each of the four wheels W. The parking brake mechanism 200 is a mechanism for mechanically operating the drum brake D, and is provided for the drum brake D provided on the two rear wheels W.

The vehicle brake hydraulic pressure control device 100 is for appropriately controlling the braking force applied to each wheel W of the vehicle CR, and is a hydraulic pressure unit 10 provided with an oil passage (hydraulic passage) and various parts. , A control unit 20 for appropriately controlling various parts in the hydraulic pressure unit 10 is mainly provided. The hydraulic unit 10 is connected to the master cylinder MC that generates brake hydraulic pressure by depressing the brake pedal BP via an oil passage, and is also connected to the wheel cylinder D4 of each drum brake D via an oil passage. .. The hydraulic pressure unit 10 includes a valve, a pump, and the like for controlling the brake hydraulic pressure applied to the foil cylinder D4.

The control unit 20 is an example of an electric parking brake control device. The control unit 20 has a function of controlling the drive and stop of the electric actuator 240 that operates the parking brake mechanism 200, and also has a function of controlling a valve and a pump in the hydraulic pressure unit 10. The control unit 20 is connected to a wheel speed sensor 91 that detects the wheel speed of the wheel W and a parking switch 92 for switching the state of the parking brake mechanism 200 between the apply state and the release state. Here, the apply state means a state in which the parking brake mechanism 200 generates a braking force. The release state means a state in which the parking brake mechanism 200 releases the braking force. Specifically, the release position is the position shown in FIG. 3, and the apply position is the position where the screw shaft 244 shown in FIG. 3 is moved to the right side of the drawing with respect to the position shown in the figure.

The parking switch 92 can be switched between an apply position and a release position. The parking switch 92 outputs an apply signal for setting the parking brake mechanism 200 to the apply state when it is located at the apply position, and releases the parking brake mechanism 200 when it is located at the release position. Is output to the control unit 20.

The control unit 20 includes, for example, a CPU, RAM, ROM, and an input / output circuit, and performs each arithmetic processing based on the input from the wheel speed sensor 91, the parking switch 92, and the like, and the programs and data stored in the ROM. By doing so, control is performed.

As shown in FIGS. 2A and 2B, the drum brake D includes a drum D1 as an example of a rotating body, a brake shoe D2 as an example of a friction member, a return spring D3, and a wheel cylinder D4. I have. The drum D1 is a member having a cylindrical portion that rotates integrally with the wheel W.

The brake shoe D2 is an arc-shaped member extending along the inner peripheral surface of the drum D1, and is pressed against the inner peripheral surface of the drum D1 to apply a braking force to the wheel W. Two brake shoes D2 are provided along the inner peripheral surface of the drum D1. One end of each of the two brake shoes D2 is rotatably supported by the support member D5, so that the two brake shoes D2 can rotate in the direction closer to each other and in the direction away from each other.

The return spring D3 urges the other ends of the two brake shoes D2 in a direction to bring them closer to each other. The foil cylinder D4 urges the two brake shoes D2 toward the inner peripheral surface of the drum D1 by the brake hydraulic pressure supplied from the hydraulic pressure unit 10.

The parking brake mechanism 200 includes a strut 210, a parking lever 220, a wire 230, and an electric actuator 240 shown in FIG. The strut 210 is engaged with the other end of each of the two brake shoes D2.

One end of the parking lever 220 is rotatably supported by one brake shoe D2 by a pin 221. A wire 230 is connected to the other end of the parking lever 220. The portion between one end and the other end of the parking lever 220, which is closer to one end, is engaged with the strut 210.

When the wire 230 is pulled to the right in the drawing, the parking lever 220 rotates about the pin 221 so that the parking lever 220 presses the other brake shoe D2 against the inner peripheral surface of the drum D1 via the strut 210. Further, when the wire 230 is pulled, the parking lever 220 rotates about the engagement portion with the strut 210, so that the parking lever 220 uses the pin 221 to move one brake shoe D2 to the inner peripheral surface of the drum D1. Press on.

As a result, each brake shoe D2 is pressed against the inner peripheral surface of the drum D1 by the pulling operation of the wire 230. When the wire 230 is loosened in the left direction in the drawing, each brake shoe D2 is separated from the inner peripheral surface of the drum D1 by the urging force of the return spring D3.

As shown in FIG. 3, the electric actuator 240 is a device for pulling the wire 230. The electric actuator 240 can give an operating force to move the brake shoe D2 via the wire 230 and move the brake shoe D2 in the direction of pressing the brake shoe D1 against the drum D1. The electric actuator 240 includes a motor 241, a plurality of gears 242, a nut 243, a screw shaft 244, and a housing 245.

The nut 243 is connected to the motor 241 via a plurality of gears 242. The nut 243 has a female screw portion 243A that meshes with the male screw portion 244A of the screw shaft 244. The screw shaft 244 is supported by the housing 245 so as to be movable in the axial direction, and the wire 230 is fixed to the tip thereof.

In this electric actuator 240, when the motor 241 is rotated in the forward direction, the screw shaft 244 moves in the direction of being accommodated in the housing 245, so that the wire 230 is pulled and the parking brake mechanism 200 applies the parking brake. It becomes a state. Further, when the motor 241 is rotated in the reverse direction, the screw shaft 244 moves in the direction of protruding from the housing 245, so that the wire 230 is loosened and the parking brake mechanism 200 is in the released state in which the parking brake is released.

As shown in FIG. 4, the control unit 20 corresponds to the processing unit 21, the storage unit 22, the motor drive units 23A and 23B which are circuits for driving each motor 241 and the motor drive units 23A and 23B, respectively. The current sensors 24A and 24B are provided. The description of the configuration for the control unit 20 to operate the hydraulic pressure unit 10 will be omitted.

The current sensors 24A and 24B are interposed between the motor drive units 23A and 23B and the motor 241 and are an example of a current monitoring unit that monitors the current flowing through each motor 241. The current detected by the current sensors 24A and 24B is input to the processing unit 21.

Further, the control unit 20 is connected to the parking switch 92, and the apply request (output of the apply signal) from the parking switch 92 is input to the processing unit 21.

The control unit 20 controls forward rotation, reverse rotation, and stop of the motor 241 based on the signal from the parking switch 92. Specifically, the control unit 20 executes initial braking control, pause control, and step-up control when an apply request is received from the parking switch 92 while the vehicle CR is traveling.

The initial braking control is a control in which the current sensors 24A and 24B continuously supply power to the electric actuator 240 until the current sensors 24A and 24B detect a second current Ath2 larger than the first current Ath1 when the brake shoe D2 starts to contact the drum D1. (See FIG. 6). The second current Ath2 is a current corresponding to an operating force that is smaller than the braking force at which at least one wheel of the vehicle CR begins to slip. As a result, it is possible to prevent the wheels W of the vehicle CR from slipping. The braking force at which at least one wheel of the vehicle CR starts to slip varies depending on the vehicle CR and the road surface condition, but the road surface has a relatively low coefficient of friction on the road surface, and can be determined by a test according to the vehicle CR.

In order to increase the braking force generated by the initial braking control and quickly apply the braking force to the vehicle CR, it is desirable that the second current Ath2 is a current suitable for decelerating the vehicle CR.

The pause control is a control in which when the current sensors 24A and 24B detect a current of the second current Ath2 or more, the power supply to the electric actuator 240 is stopped for a predetermined time TS1 (see FIG. 6). The predetermined time TS1 here can be determined by a test in consideration of the behavior such as the stability of the vehicle CR and the impression (brake feeling) given to the driver.

The step-up control is a control in which the operating force is stepwise increased by repeating feeding and stopping the electric actuator 240 after the pause control. In the present embodiment, the power supply is executed for the time of TA1 and the stop is executed for the time of TS2 (see FIG. 6). The time TS2 may be the same as or shorter than the predetermined time TS1, but in the present embodiment, it is shorter than the predetermined time TS1.
In the present embodiment, when the current detected by the current sensors 24A and 24B in the step-up control becomes the third current Ath3 or more, it is assumed that the maximum operating force is generated, and the rotation of the motor 241 is stopped.

Further, in the present embodiment, the operating force to be increased in the initial braking control is larger than the operating force to be increased by operating the electric actuator 240 once in the step-up control. Here, to operate the electric actuator 240 once means to continuously move the motor 241 once, from the state where the motor 241 is stopped to the forward rotation and then the rotation stop. say. When the brake is a drum brake as in the present embodiment, the operating force is a traction force that pulls a wire. When the brake is a disc brake, the operating force is a pressing force that pushes the brake pad.

Next, an example of the processing of the control unit 20 will be described in detail.
The processing of the flowchart of FIG. 5 is repeatedly executed by the control unit 20 while the vehicle CR is traveling. Further, this process is performed on each of the drum brakes D and the current sensors 24A and 24B provided on the two wheels W. The processing of the flowchart of FIG. 5 is performed in response to the apply request by the operation of the parking switch 92, and the release request by the operation of the parking switch 92 is separately constantly monitored by the processing unit 21. When there is a release request, the processing unit 21 rotates the motor 241 in the reverse direction to operate the parking brake mechanism 200 in the released state. A parking brake control different from that shown in FIG. 5 is performed in response to an apply request while the vehicle CR is stopped. Whether the vehicle CR is stopped or running can be determined based on the signal of the wheel speed sensor 91.

As shown in FIG. 5, the control unit 20 determines whether or not there is an apply request while the vehicle CR is traveling (S11), and if it determines that there is no apply request (S11, No), the process ends. do.

When the control unit 20 determines that the apply request has been made while the vehicle CR is traveling (S11, Yes), the control unit 20 rotates the motor 241 in the forward direction (S21) and enters the initial braking control (S21 to S22). Then, it is determined whether the detected current A detected by the current sensors 24A and 24B is the second current Ath2 or more (S22). When the control unit 20 determines that the detection current A is not the second current Ath2 or more (S22, No), the control unit 20 continues the forward rotation of the motor 241 and waits until the second current Ath2 or more is reached, and the detection current A becomes the second current. When it is determined that the current level is Ath2 or higher (S22, Yes), the motor 241 is stopped (S31), and the pause control is started (S31 to S34).

In the pause control, the control unit 20 counts the timer T (S32) and determines whether or not the timer T is TS1 or more for a predetermined time (S33). When the control unit 20 determines that the timer T is not TS1 or more for a predetermined time (S33, No), the control unit 20 returns to step S32 and repeats the counting of the timer T and the determination of step S33. When the control unit 20 determines that the timer T has reached TS1 or more for a predetermined time (S33, Yes), the timer T is reset (S34), the motor 241 is rotated forward (S41), and the step-up control (S41 to S54) is performed. )to go into.

In the step-up control, the control unit 20 counts the timer T (S42) and determines whether or not the timer T is the time TA1 or more (S43). When the control unit 20 determines that the timer T is not the time TA1 or more (S43, No), the control unit 20 further determines whether the detection current A is the third current At3 or more (S44). When the control unit 20 determines that the detection current A is not equal to or higher than the third current Ath3 (S44, No), the control unit 20 continues the forward rotation of the motor 241 and returns to step S43 to repeat the determination of the timer T. On the other hand, when the control unit 20 determines that the detection current A is equal to or higher than the third current Ath3 (S44, Yes), the control unit 20 stops the motor 241 (S61) and ends the process.

In step S43, when the control unit 20 determines that the timer T is the time TA1 or more (S43, Yes), the timer T is reset (S45) and the motor 241 is stopped (S51). After that, in order to stop the motor 241 during the time TS2, the control unit 20 counts the timer T (S52) and determines whether or not the timer T is the time TS2 or more (S53). When the control unit 20 determines that the timer T is not the time TS2 or more (S53, No), the control unit 20 returns to step S52 and repeats the counting of the timer T and the determination of step S53. When the control unit 20 determines that the timer T has reached the time TS2 or more (S53, Yes), it resets the timer T (S54), returns to step S41, and repeats the process. That is, the motor 241 is rotated in the forward direction again to gradually increase the operating force and the braking force.

The operation of the apply control during traveling by the above processing will be described with reference to FIG.
When an apply request is input to the control unit 20 by the driver operating the parking switch 92 during traveling (t1), the control unit 20 applies a current to the motor 241 so as to rotate the motor 241 in the normal direction. When a current does not flow through the motor 241 and the current starts to flow, an inrush current flows through the motor 241. However, this inrush current is removed by a known filter and does not affect the control (time t4, t6, t8). , T10).

When the brake shoe D2 comes into contact with the inner peripheral surface of the drum D1 after the motor 241 starts to rotate in the forward direction, the motor current starts to increase and becomes the first current Ath1 (t2). Then, when the motor 241 is further rotated in the forward direction, the motor current further increases and reaches the second current Ath2 (t3). When the motor current becomes the second current Ath2 or more, the control unit 20 stops the motor 241 for a predetermined time TS1 (t3 to t4). At this time, the wire 230 of the drum brake D is given an operating force of the magnitude of F1. When the operating force F1 is given, the wheel W does not slip, but a sufficiently large braking force is generated to brake the vehicle CR.

Then, the control unit 20 stops the motor 241 during the predetermined time TS1 and then rotates the motor 241 in the forward direction until the time TA1 elapses (t4 to t5). As a result, the operating force and the braking force are further increased, and after the time TA1 elapses (t5), the operating force becomes F2. Since the load of pressing the brake shoe D2 against the inner peripheral surface of the drum D1 becomes large, the motor current at the time t5 becomes larger than that at the time t3.

Then, the control unit 20 stops the motor 241 at the time t5, and stops the motor 241 during the time TS2 (t5 to t6). After the time TS2 elapses, the control unit 20 again rotates the motor 241 in the forward direction during the time TA1 (t6 to t7), and stops the motor 241 during the time TS2 after the time TA1 elapses. The operation (t7 to t8) is repeated.
As the motor 241 rotates in the forward direction, the motor current and the operating force increase, and at time t7, the operating force becomes F3.

Then, at time t8, the control unit 20 tries to rotate the motor 241 in the forward direction again during the time TA1 (t8), but when the motor current reaches the third current Ath3, the maximum operating force and braking force are exerted. As if it occurred, the motor 241 is stopped (t9). As a result, the operating force becomes F4.
In this way, the operating force gradually increases in the order of F1 → F2 → F3 → F4, but the operating force F1 to be increased in the initial braking control is increased by operating the electric actuator 240 once in the step-up control. It is larger than the operating force (F2-F1, F3-F2, and F4-F3, respectively).

At time t10, when the driver operates the parking switch 92 to move from the apply position to the release position, the control unit 20 reverses the motor 241 (t10 to t11). As a result, the operating force and the braking force are reduced, and finally become 0.

In this way, according to the control unit 20 of the present embodiment, when the apply request which is an instruction to operate the electric parking brake is input while the vehicle CR is running, the current sensors 24A and 24B cause the brake shoes D2. The parking brake mechanism 200 is started to operate because the initial braking control for continuously supplying power to the electric actuator 240 is executed until the second current Ath2, which is larger than the first current Ath1 when the first current Ath2 starts to come into contact with the drum D1, is detected. Initially, a large braking force can be generated and the braking force can be quickly applied to the vehicle CR.

Further, since the second current Ath2 is a current corresponding to a braking force smaller than the braking force at which at least one wheel of the vehicle CR starts to slip, the wheels W of the vehicle CR are less likely to slip and stabilize the behavior of the vehicle CR. be able to.

Further, the operating force F1 to be increased in the initial braking control is based on the operating force (F2-F1, F3-F2, and F4-F3, respectively) increased by operating the electric actuator 240 once in the step-up control. Therefore, the braking force can be applied to the vehicle CR more quickly.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment and can be used in various forms as illustrated below.

For example, the flowchart shown in FIG. 5 is an example of processing, and the present invention can be realized by other processing. For example, in the step-up control, the start and end of the forward rotation of the motor may be managed not by the time but by the absolute value or the amount of change of the current.

In the above embodiment, the control unit 20 of the vehicle brake hydraulic pressure control device 100 is exemplified as the electric parking brake control device, but the present invention is not limited to this, and the control device is different from the vehicle brake hydraulic pressure control device. For example, an ECU (Electronic Control Unit) may be used as an electric parking brake control device.

In the above embodiment, the parking brake mechanism 200 installed on the drum brake D has been illustrated, but the present invention is not limited to this, and for example, the parking brake mechanism installed on the disc brake may be used.

Each element described in the above-described embodiment and modification may be arbitrarily combined and implemented.

20 Control unit 24A, 24B Current sensor 92 Parking switch 100 Vehicle brake hydraulic pressure control device 200 Parking brake mechanism 240 Electric actuator 241 Motor CR Vehicle D Drum brake D1 Drum D2 Brake shoe

Claims (3)

A rotating body that rotates integrally with the wheel, a friction member that generates a braking force on the wheel by being pressed against the rotating body, and an electric actuator that gives an operating force that moves the friction member in a direction of pressing the friction member against the rotating body. It is an electric parking brake control device that controls the parking brake device provided.
Equipped with a current monitoring unit that monitors the current of the electric actuator
When an instruction to operate the electric parking brake is input while the vehicle is running, the current monitoring unit detects a second current larger than the first current when the friction member starts to come into contact with the rotating body. Up to, the initial braking control that continuously supplies power to the electric actuator,
When the current monitoring unit detects a current equal to or higher than the second current, the temporary stop control for stopping the power supply to the electric actuator for a predetermined time and
An electric parking brake control device characterized by executing step-up control in which an operating force is stepwise increased by repeating power supply and stop to the electric actuator after the pause control. The electric parking brake control device according to claim 1, wherein the second current is a current corresponding to an operating force that is a braking force smaller than a braking force at which at least one wheel starts to slip. The electric motor according to claim 1 or 2, wherein the operating force to be increased in the initial braking control is larger than the operating force to be increased by operating the electric actuator once in the step-up control. Parking brake control device.

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