JP7425648B2 - 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, as an electric parking brake control device, one is known that reduces the influence of heat generation of an electric actuator caused by continuous operation of a parking switch due to mischief by a driver or the like (see Patent Document 1). Specifically, in this technique, when the cumulative operation time of the actuator within a certain period of time exceeds a predetermined threshold, the operation of the electric actuator is prohibited for a certain period of time.

Patent No. 6018535

In the conventional technology, the state of the parking brake mechanism when the cumulative operation time exceeds a predetermined threshold value can be either an applied state in which braking force is generated or a released state in which braking force is released. . Therefore, if the parking brake mechanism is in the applied state when attempting to start the vehicle during the predetermined time during which the electric actuator is prohibited from operating, the braking force cannot be easily released and the vehicle will not move smoothly. The problem arises that the vehicle cannot start.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to prevent the start of a vehicle from being inhibited during a period in which the operation of the electric actuator is prohibited.

In order to solve the above problems, an electric parking brake control device according to the present invention is an electric parking brake control device that controls driving and stopping of an electric actuator that operates a parking brake mechanism, wherein the parking brake mechanism exerts a braking force. an apply process in which the electric actuator is driven to be in an apply state where the parking brake is generated; a release process in which the electric actuator is driven to be in a release state in which the parking brake mechanism releases the braking force; and within a first predetermined time. , a counting process for counting the number of releases, which is the number of times the release process has been executed, and when the number of releases reaches a predetermined number within the first predetermined time, completing the release process for the predetermined number of times, and For a second predetermined period of time after completion of the release process, a prohibition process is performed in which driving of the electric actuator is prohibited while the parking brake mechanism is maintained in the released state .

According to this configuration, even if the parking switch is switched multiple times in a short period of time due to mischief by an occupant, etc., when the number of releases reaches a predetermined number, driving of the electric actuator is prohibited, so the parking It is possible to suppress heat generation in the electric actuator due to the switch being switched multiple times in a short period of time. By executing the prohibition process after the completion of the predetermined number of release processes, the state of the parking brake during the prohibition process becomes the released state, so that it is possible to prevent the vehicle from being inhibited from starting.

Further, the electric parking brake control device may be configured not to execute the apply process even if there is a request for the apply process during the predetermined number of release processes.

Further, the electric parking brake control device may reset the number of times of release when the number of times of release does not reach the predetermined number of times and the first predetermined time has elapsed.

Further, the electric parking brake control device may count the stop time of the electric actuator within the first predetermined time, and reset the number of releases when the stop time reaches a threshold value.

According to the present invention, it is possible to prevent the start of the vehicle from being inhibited during the period in which the operation of the electric actuator is prohibited.

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. 5 is a flowchart showing processing by a control unit. It is a flowchart which shows actuator drive processing. It is a flowchart which shows prohibition processing. 5 is a time chart illustrating an example in which prohibition processing is started. It is a time chart showing an example in which the first timer and the like are reset when the stop time reaches a threshold value.

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 a 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.

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, a brake shoe D2, a return spring D3, and a foil cylinder D4. 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 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 causing the parking brake mechanism 200 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.

In the following explanation, the position of the screw shaft 244 when the parking brake mechanism 200 is in the applied state is also referred to as the "apply position", and the position of the screw shaft 244 when the parking brake mechanism 200 is in the release state. is also referred to as the "release position". 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 control unit 20 controls forward rotation, reverse rotation, and stopping of the motor 241 based on a signal from the parking switch 92. The control unit 20 has a function of executing an apply process, a release process, a count process, and a prohibition process. In the following description, the output of the apply signal from the parking switch 92 is also referred to as a "request for apply processing," and the output of the release signal from the parking switch 92 is also referred to as a "request for release processing."

The apply process is a process in which the electric actuator 240 is driven so that the parking brake mechanism 200 is in the apply state. Specifically, upon receiving a request for apply processing, the control unit 20 causes the motor 241 to rotate forward to move the screw shaft 244 to the apply position, thereby placing the parking brake mechanism 200 in the apply state.

The release process is a process of driving the electric actuator 240 so that the parking brake mechanism 200 is in a released state. Specifically, upon receiving a request for release processing, the control unit 20 reversely rotates the motor 241 to move the screw shaft 244 to the release position, thereby placing the parking brake mechanism 200 in the release state.

The counting process is a process of counting the number of releases, which is the number of times the release process has been executed, within the first predetermined time T1. Specifically, when the control unit 20 determines that the vehicle CR has stopped based on the wheel speed detected by the wheel speed sensor 91 and determines that there is a request for apply processing or release processing, the control unit 20 starts the count by the first timer TM1. is started, and the number of releases N is counted each time the release process is executed until the time counted by the first timer TM1 reaches the first predetermined time T1. Note that the vehicle CR may be determined to have stopped when, for example, the vehicle body speed determined from the wheel speed becomes equal to or less than a predetermined value.

Further, the control unit 20 has a function of resetting the number of releases N when the number of releases N does not reach the predetermined number Nth and the first predetermined time T1 has elapsed. Furthermore, the control unit 20 also has a function of counting the stop time TS of the electric actuator 240 within the first predetermined time T1, and resetting the number of releases N when the stop time TS reaches a threshold value Tth.

The prohibition process is to complete a predetermined release process when the number of releases N reaches a predetermined number Nth within a first predetermined time T1, and to stop the electric motor from being activated for a second predetermined time T2 after completion of the release process. This is a process of prohibiting the actuator 240 from being driven. Specifically, after completing the release process for a predetermined number of times, the control unit 20 starts counting by the second timer TM2, and until the time counted by the second timer TM2 reaches the second predetermined time T2, Prohibits execution of apply and release operations.

Here, in the present embodiment, if the parking brake mechanism 200 is always in the released state, regardless of whether the prohibition process is in progress, the control unit 20 is configured to release the parking brake even if there is a request for the release process. It is configured not to perform any processing. Further, the control unit 20 is configured not to perform the apply process even if there is a request for the apply process when the parking brake mechanism 200 is always in the apply state.

Note that the state of the parking brake mechanism 200 may be determined based on, for example, a signal from a sensor that detects the position of the screw shaft 244, or may be determined based on a previous request.

During the counting process (within the first predetermined time T1), the control unit 20 does not execute the apply process even if there is a request for the apply process during the execution of the release process, and performs the release process during the execution of the apply process. The system is configured so that release processing is not executed even if there is a request. Thereby, the control unit 20 does not execute the apply process even if there is a request for the apply process during the predetermined number of release processes.

Next, the processing of the control unit 20 will be described in detail with reference to FIGS. 4 to 6. The control unit 20 constantly repeatedly executes the process shown in FIG.

In the process of FIG. 4, the control unit 20 first determines whether the vehicle CR has stopped (S1). If it is determined in step S1 that the vehicle CR is not stopped (No), the control unit 20 ends this process.

If it is determined in step S1 that the vehicle CR has stopped (Yes), the control unit 20 determines whether there is a request for apply processing or release processing (S2). If it is determined in step S2 that there is no request (No), the control unit 20 ends this process.

If it is determined in step S2 that there is a request (Yes), the control unit 20 starts counting the first timer TM1 and starts counting the stop time TS of the electric actuator 240 (S3). After step S3, the control unit 20 executes actuator drive processing (S4), and then ends this processing.

As shown in FIG. 5, in the actuator drive process, the control unit 20 first determines whether the current request is different from the previous request (S11). If it is determined in step S11 that the current request is different from the previous request (Yes), the control unit 20 determines whether the current request is a request for apply processing (S12).

If it is determined in step S12 that the request is for apply processing (Yes), the control unit 20 executes the apply processing (S13). If it is determined in step S12 that it is not a request for apply processing (No), the control unit 20 counts up the number of releases N (S14) and executes the release processing (S15).

After step S13 or step S15, the control unit 20 determines whether the number of releases N is equal to or greater than a predetermined number of times Nth (S16). If it is determined in step S16 that N≧Nth is not satisfied (No), the control unit 20 determines whether or not the first predetermined time T1 has elapsed since starting the actuator drive process, that is, it has been counted by the first timer TM1. It is determined whether the time has exceeded the first predetermined time T1 (S17). Note that if the control unit 20 determines in step S11 that the current request is the same as the previous request (No), it does not perform steps S12 to S16, that is, it does not count up the number of releases N and apply The process moves to step S17 without executing the process and the release process.

If it is determined in step S17 that the first predetermined time T1 has not elapsed (No), the control unit 20 determines whether the stop time TS of the motor 241 is equal to or greater than the threshold value Tth (S18). If it is determined in step S18 that TS≧Tth (No), the control unit 20 determines whether there is a request for apply processing or release processing (S19).

If it is determined in step S19 that there is a request (Yes), the control unit 20 returns to the process in step S11. If it is determined in step S19 that there is no request (No), the control unit 20 returns to the process in step S17. If it is determined Yes in step S17 or step S18, the control unit 20 resets the time counted by the first timer TM1, the stop time TS, and the number of releases N (S22), and ends this process.

If it is determined in step S16 that N≧Nth (Yes), the control unit 20 resets the time counted by the first timer TM1, the stop time TS, and the number of releases N (S20), and performs the prohibition process. The process is executed (S21), and then the process ends.

As shown in FIG. 6, in the prohibition process, the control unit 20 first starts counting the second timer TM2 (S41). After step S41, the control unit 20 determines whether the second predetermined time T2 has elapsed since the start of the prohibition process, that is, whether the time counted by the second timer TM2 has exceeded the second predetermined time T2. (S42).

While it is determined in step S42 that the second predetermined time T2 has not elapsed (No), the control unit 20 waits for the second predetermined time T2 to elapse without doing anything. Thereby, the control unit 20 does not execute the apply process and the release process even if there is a request for the apply process and the release process during the prohibition process, that is, during the second predetermined time T2.

If it is determined in step S42 that the second predetermined time T2 has elapsed (Yes), the control unit 20 resets the time counted by the second timer TM2 (S43), and ends this process.

Next, an example of the operation of the control unit 20 will be described in detail with reference to FIGS. 7 and 8. The example shown in FIG. 7 shows an example in which prohibition processing is started. The example shown in FIG. 8 shows an example in which the first timer TM1 and the like are reset when the stop time TS reaches the threshold value Tth.

In the example shown in FIG. 7, when the first request is made after it is determined that the vehicle CR has stopped (time t1), the control unit 20 starts counting the first timer TM1 and increments the number of releases N. Then, the process (release process in the figure) according to the request is executed, that is, the motor 241 is driven.

When the release process ends (time t2), the control unit 20 stops the motor 241 and counts the stop time TS. Thereafter, when the parking switch 92 is operated continuously due to mischief or the like by an occupant, the control unit 20 operates the motor 241 in accordance with the request each time, and accumulates the number of releases N and the stop time TS (time t3 ~t4).

When the number of releases N reaches the predetermined number Nth within the first predetermined time T1 (time t4), the control unit 20 executes the release process for the predetermined number of times to the end, then executes the prohibition process, and performs the second release process. The timer TM2 starts counting (time t5). Also, at this time, the control unit 20 resets the number of releases N, the first timer TM1, and the stop time TS.

During the prohibition process, the control unit 20 does not execute the apply process and the release process, that is, does not operate the motor 241 even if there is a request for the apply process and the release process (times t5 to t6). Thereby, overheating of the motor 241 can be suppressed.

Furthermore, since the prohibition process is started upon completion of the predetermined number of release processes, the state of the parking brake mechanism 200 is always maintained in the released state during the prohibition process. Thereby, during the prohibition process, the vehicle CR is in a state where it can start smoothly.

When the second timer TM2 reaches the second predetermined time T2 (time t6), the control unit 20 ends the prohibition process and resets the second timer TM2. Note that after that, if the vehicle CR is still stopped, the control unit 20 executes the process according to the request when there is a request (time t7), and also causes the first timer TM1 to count again.

In the example shown in FIG. 8 as well, similarly to the example shown in FIG. 7, processing in response to a request is executed, and the number of releases N, stop time TS, etc. are counted (times t21 to t22). However, in the example shown in FIG. 8, since the number of operations of the parking switch 92 by the occupant is small, the motor 241 remains stopped for a long time, and the stop time TS reaches the threshold value Tth within the first predetermined time T1 (time t22).

When the stop time TS reaches the threshold Tth (time t22), the control unit 20 resets the number of releases N, the first timer TM1, and the stop time TS. Although not shown, the reset of the number of releases N, etc. when the number of releases N does not reach the predetermined number Nth is also performed after the first predetermined time T1 has elapsed (S17: Yes).

Here, for example, if the parking switch 92 is continuously operated in the second half of the first predetermined time T1 and the first predetermined time T1 has elapsed before the number of releases N reaches the predetermined number Nth, the predetermined number of times Nth The number of releases N that has been accumulated up to this point will be reset. Therefore, in this case, even if a new first predetermined time T1 is set thereafter, the count of the number of releases N will start from 0, so there is a risk that the actual number of releases will exceed the predetermined number Nth, and the motor 241 will overheat. There is a risk.

On the other hand, when resetting the first timer TM1 etc. based on the stop time TS, the first timer TM1 etc. can be reset before the first predetermined time T1 elapses, so the new first predetermined time T1 can be reset. You can reset the settings at an early stage. Thereby, overheating of the motor 241 can be suppressed better.

According to the above, the following effects can be obtained in this embodiment.
Even if the parking switch 92 is switched multiple times in a short period of time due to mischief by an occupant, etc., when the number of releases N reaches the predetermined number Nth, driving of the electric actuator 240 is prohibited. It is possible to suppress heat generation in the electric actuator 240 due to being switched multiple times in a short period of time. Furthermore, during the second predetermined time T2 during which driving of the electric actuator 240 is prohibited, the state of the parking brake mechanism 200 is in the released state, so that it is possible to prevent the vehicle CR from being inhibited from starting. can.

Regardless of whether the prohibition process is executed or not, the control unit 20 prohibits the execution of the release process when the parking brake mechanism 200 is in the released state, thereby better suppressing unnecessary operation of the electric actuator 240. can do.

Note that the present invention is not limited to the embodiments described above, and can be utilized in various forms as exemplified below.

In the embodiment described above, the apply process is not executed when the parking brake mechanism 200 is in the apply state, and the release process is not executed when the parking brake mechanism 200 is in the release state. However, the present invention is not limited thereto. For example, it may be configured to perform the apply process and the release process regardless of the state of the parking brake mechanism.

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.

In the above embodiment, during the counting process, the apply process or the release process is executed to the end without stopping midway, but the present invention is not limited to this, and the release process for a predetermined number of times during the counting process If an apply process is requested while the release process is being executed, the release process may be stopped midway and the apply process may be executed. In this case, release processing that is stopped midway may be considered to have been executed and the number of releases may be counted. In this case, the configuration may be such that the requested apply process is not executed only when a request for the apply process is made during the predetermined number of release processes.

In the embodiment, the reset condition such as the number of releases N is set to satisfy TM1≧T1 or TS≧Tth, but the present invention is not limited to this. For example, the reset condition is set to satisfy TM1≧T1. It may also be used alone.

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

20 Control part 200 Parking brake mechanism 240 Electric actuator N Number of releases Nth Predetermined number of times T1 First predetermined time T2 Second predetermined time

Claims (4)

An electric parking brake control device that controls driving and stopping of an electric actuator that operates a parking brake mechanism,
an apply process of driving the electric actuator so that the parking brake mechanism is in an apply state in which it generates a braking force;
a release process in which the electric actuator is driven so that the parking brake mechanism is in a release state in which the braking force is released;
A counting process that counts the number of times the release process is executed within a first predetermined time;
If the number of releases reaches a predetermined number within the first predetermined time period, the predetermined number of release processes is completed, and the parking brake mechanism is operated as described above for a second predetermined time period after the completion of the release process. An electric parking brake control device characterized by executing a prohibition process of prohibiting driving of the electric actuator while the electric actuator is maintained in a released state . The electric parking brake control device according to claim 1, wherein the apply processing is not executed even if the apply processing is requested during the predetermined number of release processing. The electric parking brake control device according to claim 1 or 2, wherein the number of times of release is reset if the number of times of release does not reach the predetermined number of times and the first predetermined time period has elapsed. Any one of claims 1 to 3, wherein the stop time of the electric actuator is counted within the first predetermined time, and when the stop time reaches a threshold value, the number of releases is reset. The electric parking brake control device described in .

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