JP7352502B2 - Electric parking brake control device - Google Patents

Description

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

Conventionally, when performing application control to apply braking force while the vehicle is running, electric parking brake control devices continuously energize the electric motor until the start of contact between the braking member and the braked member is detected. It is known that when the start of contact with the braked member is detected, step-up control is performed in which the clamping force of the braking member against the braked member is increased in stages by repeatedly activating and stopping the electric motor.

Patent No. 6392895

However, in the conventional technology, when performing apply control while the vehicle is running, when contact between the braking member and the braked member is detected, the electric motor is stopped, so there is a problem that braking force cannot be applied to the vehicle promptly. was there.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to quickly apply braking force to a vehicle when an electric parking brake is activated while the vehicle is running.

In order to solve the above problems, an electric parking brake control device according to the present invention includes a rotating body that rotates together with a wheel, a friction member that generates braking force on the wheel by being pressed against the rotating body, and a friction member that rotates the friction member. An electric parking brake control device that controls a parking brake device including an electric actuator that applies an operating force to move in a direction of pressing against a body, and includes a current monitoring unit that monitors a 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 detects a second current larger than a first current when the friction member starts contacting the rotating body. initial braking control that continuously supplies power to the electric actuator until a current is detected; temporary stop control that stops power supply to the electric actuator for a predetermined period of time when the current monitoring unit detects a current equal to or higher than the second current; After the stop control, step-up control is performed in which the operating force is increased step by step by repeating power supply and stop to the electric actuator.

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 detects a first current larger than the first current when the friction member starts contacting the rotating body. Since the initial braking control is performed by continuously supplying power to the electric actuator until the electric parking brake is detected, a large braking force can be generated at the beginning of the electric parking brake operation, and the braking force can be quickly applied to the vehicle. can.

The second current described above is preferably a current corresponding to an operating force that results in a braking force smaller than the braking force at which at least one wheel begins to slip.

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

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

According to such a configuration, 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 to operate the electric parking brake, and the braking force can be quickly applied to the vehicle.

1 is a configuration diagram of a vehicle equipped with a vehicle brake fluid pressure control device according to an embodiment of the present invention. FIG. 2 is a diagram showing a drum brake and a parking brake mechanism, with (a) showing a state in which the brake is not applied, and (b) showing a state in which the brake is applied by the parking brake mechanism. It is a sectional view showing an electric actuator of a parking brake mechanism. It is a block diagram of a control part. It is a flowchart which shows the process when applying control of an electric parking brake during driving. 12 is a timing chart when an apply request is made while the vehicle is running.

Next, embodiments 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 brakes D, and is provided for the drum brakes D provided on the two rear wheels W.

The vehicle brake fluid pressure control device 100 is for appropriately controlling the braking force applied to each wheel W of the vehicle CR, and includes a hydraulic unit 10 provided with oil passages (hydraulic pressure passages) and various parts. , and a control section 20 for appropriately controlling various parts within the hydraulic unit 10. The hydraulic unit 10 is connected via an oil path to a master cylinder MC that generates brake fluid pressure when the brake pedal BP is depressed, and is also connected to a wheel cylinder D4 of each drum brake D via an oil path. . The hydraulic unit 10 includes a valve, a pump, and the like for controlling brake hydraulic pressure applied to the wheel 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 driving and stopping of an electric actuator 240 that operates the parking brake mechanism 200, and also has a function of controlling valves and pumps in the hydraulic unit 10. A wheel speed sensor 91 that detects the wheel speed of the wheel W and a parking switch 92 that switches the state of the parking brake mechanism 200 between an applied state and a released state are connected to the control unit 20. Here, the apply state refers to a state in which the parking brake mechanism 200 generates a braking force. Further, the release state refers to 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 shown in FIG. 3, where the screw shaft 244 is moved to the right in the figure from 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 to the control unit 20 for putting the parking brake mechanism 200 in the applied state when it is located at the apply position, and puts the parking brake mechanism 200 in the released state when it is located at the release position. A release signal is output to the control section 20.

The control unit 20 includes, for example, a CPU, a RAM, a ROM, and an input/output circuit, and performs various calculation processes based on inputs from a wheel speed sensor 91, a parking switch 92, etc., and programs and data stored in the ROM. Execute control by doing.

As shown in FIGS. 2(a) and 2(b), 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 foil cylinder D4. We are prepared. The drum D1 is a member having a cylindrical portion that rotates together with the wheel W.

The brake shoe D2 is an arcuate member extending along the inner circumferential surface of the drum D1, and applies braking force to the wheel W by being pressed against the inner circumferential surface of the drum D1. 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 a support member D5, so that the two brake shoes D2 can be rotated in a direction toward each other and a direction in which they are separated from each other.

The return spring D3 biases the other ends of the two brake shoes D2 in a direction toward each other. The foil cylinder D4 urges the two brake shoes D2 toward the inner circumferential surface of the drum D1 by the brake fluid 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 a pin 221 on one brake shoe D2. A wire 230 is connected to the other end of the parking lever 220. A portion of the parking lever 220 between one end and the other end, which is closer to the one end, engages with the strut 210.

When the wire 230 is pulled to the right in the drawing, the parking lever 220 rotates around the pin 221, thereby pressing 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 around the engagement portion with the strut 210, so that the parking lever 220 moves one brake shoe D2 to the inner peripheral surface of the drum D1 via the pin 221. to press against.

As a result, each brake shoe D2 is pressed against the inner circumferential surface of the drum D1 by the tensioning action of the wire 230. Note that when the wire 230 is loosened to the left in the drawing, each brake shoe D2 is separated from the inner peripheral surface of the drum D1 due to the biasing force of the return spring D3.

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

Nut 243 is connected to motor 241 via a plurality of gears 242. The nut 243 has a female threaded portion 243A that engages with a male threaded 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 has the wire 230 fixed to its tip.

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, thereby pulling the wire 230, and the parking brake mechanism 200 is activated to apply the parking brake. 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, thereby loosening the wire 230 and putting the parking brake mechanism 200 in a released state in which the parking brake is released.

As shown in FIG. 4, the control unit 20 corresponds to a processing unit 21, a storage unit 22, motor drive units 23A and 23B, which are circuits that drive each motor 241, and motor drive units 23A and 23B, respectively. The current sensors 24A and 24B are provided. Note that a description of the configuration for the control section 20 to operate the hydraulic 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 examples of current monitoring units that monitor the current flowing through each motor 241. The currents detected by the current sensors 24A and 24B are input to the processing section 21.

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

The control unit 20 controls forward rotation, reverse rotation, and stopping of the motor 241 based on a signal from the parking switch 92. Specifically, when there is an application request from the parking switch 92 while the vehicle CR is running, the control unit 20 executes initial braking control, temporary stop control, and step-up control.

The initial braking control is control in which power is continuously supplied to the electric actuator 240 until the current sensors 24A, 24B detect a second current Ath2 that is larger than the first current Ath1 when the brake shoes D2 start contacting the drum D1. (See Figure 6). The second current Ath2 is a current corresponding to an operating force that is a braking force smaller than the braking force at which at least one wheel of the vehicle CR begins to slip. Thereby, it is possible to suppress 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 road surface conditions, but can be determined by testing depending on the vehicle CR, using a road surface with a relatively low coefficient of friction.

In order to increase the braking force generated in 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 temporary stop control is a control that stops power supply to the electric actuator 240 for a predetermined time TS1 when the current sensors 24A, 24B detect a current equal to or higher than the second current Ath2 (see FIG. 6). The predetermined time TS1 here can be determined through a test, taking into account the behavior of the vehicle CR, such as how easily it stabilizes, and the impression given to the driver (brake feeling).

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

Further, in the present embodiment, the operating force increased in the initial braking control is larger than the operating force increased by operating the electric actuator 240 once in the step-up control. Here, operating the electric actuator 240 once refers to continuously moving the motor 241 once, and refers to the state in which the motor 241 is rotated in the forward direction from a stopped state, and then until the rotation is stopped. say. When the brake is a drum brake as in this embodiment, the operating force is a traction force that pulls a wire. Further, when the brake is a disc brake, the operating force is a pressing force that pushes the brake pad.

Next, an example of processing by the control unit 20 will be described in detail.
The process of the flowchart in FIG. 5 is repeatedly executed by the control unit 20 while the vehicle CR is running. Further, this process is performed for each drum brake D and each current sensor 24A, 24B provided on the two wheels W. The processing in the flowchart of FIG. 5 is performed in response to an apply request made by operating the parking switch 92, and a release request made by operating the parking switch 92 is separately monitored by the processing unit 21 at all times. When there is a release request, the processing unit 21 reversely rotates the motor 241 to operate the parking brake mechanism 200 to the released state. Note that in response to an apply request while the vehicle CR is stopped, parking brake control different from that in FIG. 5 is performed. Whether the vehicle CR is stopped or running can be determined based on the signal from 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 running (S11), and if it is determined that there is no apply request (S11, No), the process ends. do.

When the control unit 20 determines that there is an apply request while the vehicle CR is running (S11, Yes), the control unit 20 rotates the motor 241 forward (S21) and enters initial braking control (S21 to S22). Then, it is determined whether the detected current A detected by the current sensors 24A and 24B is equal to or greater than the second current Ath2 (S22). If the control unit 20 determines that the detected current A is not equal to or greater than the second current Ath2 (S22, No), the control unit 20 continues to rotate the motor 241 in the forward direction, waits until the detected current A becomes equal to or greater than the second current Ath2, and then detects the detected current A as the second current. When it is determined that Ath2 or more is reached (S22, Yes), the motor 241 is stopped (S31), and temporary stop control is entered (S31 to S34).

In the temporary stop control, the control unit 20 counts the timer T (S32), and determines whether the timer T is longer than the predetermined time TS1 (S33). When the control unit 20 determines that the timer T is not longer than the predetermined time TS1 (S33, No), the control unit 20 returns to step S32 and repeats the counting of the timer T and the determination in step S33. When the control unit 20 determines that the timer T has exceeded the predetermined time TS1 (S33, Yes), it resets the timer T (S34), rotates the motor 241 forward (S41), and performs step-up control (S41 to S54). )to go into.

In the step-up control, the control unit 20 counts the timer T (S42), and determines whether the timer T is equal to or longer than the time TA1 (S43). When the control unit 20 determines that the timer T is not equal to or longer than the time TA1 (S43, No), the control unit 20 further determines whether the detected current A is equal to or greater than the third current Ath3 (S44). When the control unit 20 determines that the detected current A is not equal to or higher than the third current Ath3 (S44, No), the control unit 20 continues to rotate the motor 241 in the forward direction, returns to step S43, and repeats the determination of the timer T. On the other hand, when the control unit 20 determines that the detected 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 equal to or longer than the time TA1 (S43, Yes), the control unit 20 resets the timer T (S45) and stops the motor 241 (S51). Thereafter, in order to stop the motor 241 for the time TS2, the control unit 20 counts the timer T (S52), and determines whether the timer T is equal to or longer than the time TS2 (S53). When the control unit 20 determines that the timer T is not longer than the time TS2 (S53, No), the control unit 20 returns to step S52 and repeats the counting of the timer T and the determination in step S53. When the control unit 20 determines that the timer T has exceeded the time TS2 (S53, Yes), the control unit 20 resets the timer T (S54), and returns to step S41 to repeat the process. That is, the motor 241 is rotated in the forward direction again, and the operating force is further gradually increased to increase the braking force.

The operation of the apply control while the vehicle is running through the above-described processing will be explained with reference to FIG. 6.
During driving, when the driver operates the parking switch 92 and an apply request is input to the control unit 20 (t1), the control unit 20 supplies current to the motor 241 so as to rotate the motor 241 in the normal direction. When current starts flowing through the motor 241 from a state where no current is flowing, an inrush current flows through the motor 241, but this inrush current is removed by a known filter and does not affect the control (times t4, t6, t8). , t10).

After the motor 241 starts to rotate forward, when the brake shoe D2 comes into contact with the inner peripheral surface of the drum D1, the motor current starts to rise 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 equal to or higher than the second current Ath2, the control unit 20 stops the motor 241 for a predetermined time TS1 (t3 to t4). At this time, an operating force of magnitude F1 is applied to the wire 230 of the drum brake D. When the operating force F1 is applied, the wheels W do not slip, but a sufficiently large braking force is generated to brake the vehicle CR.

Then, after stopping the motor 241 for a predetermined time TS1, the control unit 20 rotates the motor 241 in the forward direction until the time TA1 has elapsed (t4 to t5). This further increases the operating force and braking force, and after time TA1 has elapsed (t5), the operating force becomes F2. Since the load that presses the brake shoe D2 against the inner circumferential surface of the drum D1 increases, the motor current at time t5 becomes larger than at time t3.

Then, the control unit 20 stops the motor 241 at time t5, and stops the motor 241 for a time TS2 (t5 to t6). After the time TS2 has elapsed, the control unit 20 rotates the motor 241 in the forward direction again for the time TA1 (t6 to t7), and after the time TA1 has elapsed, the control unit 20 stops the motor 241 for the time TS2. Repeat the operation (t7-t8).
As the motor 241 rotates forward, the motor current and operating force increase, and at time t7, the operating force becomes F3.

Then, at time t8, the control unit 20 tries again to rotate the motor 241 in the forward direction during time TA1 (t8), but when the motor current reaches the third current Ath3, the maximum operating force and braking force are reduced. Assuming that this has occurred, the motor 241 is stopped (t9). As a result, the operating force becomes F4.
In this way, the operating force gradually increases from F1 to F2 to F3 to 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 it 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 braking force decrease and eventually become zero.

In this way, according to the control unit 20 of the present embodiment, when an apply request, which is an instruction to operate the electric parking brake while the vehicle CR is running, is input, the current sensors 24A and 24B Since the initial braking control of 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 motor starts contacting the drum D1, is detected, the parking brake mechanism 200 starts to operate. It is possible to generate a large braking force in the initial stage and immediately apply the braking force to the vehicle CR.

In addition, 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 begins to slip, so that the wheel W of the vehicle CR is less likely to slip and the behavior of the vehicle CR is stabilized. be able to.

Furthermore, the operating force F1 to be increased in the initial braking control is greater than the operating force (F2-F1, F3-F2, and F4-F3, respectively) to be increased by operating the electric actuator 240 once in the step-up control. By also having a large braking force, 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 embodiment and can be utilized in various forms as exemplified below.

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

In the embodiment, the control unit 20 of the vehicle brake fluid pressure control device 100 is illustrated as an electric parking brake control device, but the present invention is not limited to this, and the present invention is not limited to this, and may be a control device other than the vehicle brake fluid pressure control device. For example, an ECU (Electronic Control Unit) may be used as an electric parking brake control device.

Although the parking brake mechanism 200 installed in the drum brake D was illustrated in the embodiment, the present invention is not limited thereto, and may be a parking brake mechanism installed in a disc brake, for example.

The elements described in the embodiments and modifications described above may be implemented in any combination.

20 Control part 24A, 24B Current sensor 92 Parking switch 100 Vehicle brake fluid 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 together 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 provides an operating force that moves the friction member in a direction that presses the friction member against the rotating body. An electric parking brake control device for controlling a parking brake device comprising:
Equipped with a current monitoring section that monitors the current of the electric actuator.
When an instruction to operate an electric parking brake is input while the vehicle is running, the current monitoring unit detects a second current that is larger than the first current when the friction member starts contacting the rotating body. an initial braking control that continuously supplies power to the electric actuator until
temporary stop control for stopping power supply to the electric actuator for a predetermined period of time when the current monitoring unit detects a current equal to or higher than the second current;
An electric parking brake control device characterized in that, after the temporary stop control, step-up control is performed in which the operating force is increased in steps by repeating power supply and stopping to the electric actuator. 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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