KR20220015343A - Electronic parking brake system and control method thereof - Google Patents

Abstract

An electronic parking brake system comprises: an electronic parking brake which provides clamping force required for parking of a vehicle by a motor; a warning unit which warns a failure of the electronic parking brake; a current sensor which detects current of the motor; and a control unit which is electrically connected with the current sensor. The control unit determines whether the clamping force is generated according to the motor current during parking, counts a time without generation of clamping force when the clamping force is not generated, and warns a possible failure of the electronic parking brake through the warning unit when the time without generation of clamping force exceeds a preliminary failure detection time that is set to be shorter than a failure detection time of the electronic parking brake. When the clamping force is not generated, the electronic parking brake system prevents a driver to leave the vehicle until determination of failure is completed.

Description

ELECTRONIC PARKING BRAKE SYSTEM AND CONTROL METHOD THEREOF

The present invention relates to an electronic parking brake system having an electronic parking brake operated by a motor and a method for controlling the same.

In general, the electronic parking brake system can generate a clamping force required for parking by increasing the torque generated from the motor through the reducer by the mechanical structure device inside the caliper.

This electronic parking brake system uses the principle that the output torque of the motor is proportional to the current, and when the current reaches a specific value, it is determined that the required clamping force is satisfied and the control is terminated.

The clamping force may not be generated due to various factors such as the reduction gear of the electronic parking brake or the mechanical damage of the mechanical structure device. If the motor current does not reach a specific value during the fault detection time, the electronic parking brake system judges that the electronic parking brake has failed and warns the driver.

However, if the driver leaves the vehicle before the failure detection time has elapsed, there may be a risk of a safety accident due to the non-occurrence of the clamping force.

Publication No. 2013-0021788 (published on March 6, 2013)

One aspect provides an electronic parking brake system and a control method thereof for preventing a driver from leaving a vehicle until a failure determination is completed when a clamping force does not occur.

According to one aspect, an electronic parking brake that provides a clamping force required for parking of a vehicle by a motor; a warning unit warning a failure of the electronic parking brake; a current sensor detecting the current of the motor; and a control unit electrically connected to the current sensor, wherein the control unit determines whether a clamping force is generated according to a motor current during parking operation, and if the clamping force does not occur, counts a time during which the clamping force is not generated, and the An electronic parking brake system that warns of a possible failure of the electronic parking brake through the warning unit may be provided when the non-clamping force non-occurrence time elapses a preliminary failure detection time set shorter than the failure detection time of the electronic parking brake.

The control unit may determine the preliminary failure detection time as a preset time.

The control unit may determine the preliminary failure detection time based on the parking release completion determination time for determining the parking release completion at the time of the previous parking release.

The control unit may store the parking release completion determination time in the memory when the previous parking is released.

The control unit may compensate the parking release completion determination time by at least one of a battery voltage and brake hydraulic pressure at the time of previous parking release.

The control unit may determine the preliminary failure detection time based on the parking release completion determination time for determining the parking release completion in the previous parking release and the battery voltage and the brake hydraulic pressure during the parking operation.

The controller may compensate the preliminary failure detection time so that the preliminary failure detection time becomes longer as the battery voltage is lowered.

The controller may compensate the preliminary failure detection time so that the preliminary failure detection time becomes longer as the brake hydraulic pressure increases.

According to another aspect, there is provided a method for controlling an electronic parking brake that provides a clamping force necessary for parking a vehicle by a motor, wherein the electric current of the motor is detected during parking operation, and the detected motor current It is determined whether the clamping force is generated according to the When elapsed, there may be provided a control method of the electronic parking brake system including warning of a possible failure of the electronic parking brake.

The warning of the suspected failure of the electronic parking brake may include determining the preliminary failure detection time as a preset time.

The warning of the suspected failure of the electronic parking brake may determine the preliminary failure detection time based on the parking release completion determination time for determining the parking release completion at the time of previous parking release.

The method may further include storing the parking release completion determination time in a memory when the previous parking is released.

The warning of the suspected failure of the electronic parking brake includes a parking release completion determination time for determining the parking release completion at the time of previous parking release, and the preliminary failure detection time based on the battery voltage and brake hydraulic pressure during the parking operation. This may include judging.

Determining the preliminary failure detection time may include compensating for the preliminary failure detection time so that the preliminary failure detection time becomes longer as the battery voltage is lowered.

Determining the preliminary failure detection time may include compensating for the preliminary failure detection time so that the preliminary failure detection time becomes longer as the brake hydraulic pressure increases.

The present invention prevents the driver from leaving the vehicle until the failure determination is completed when the clamping force does not occur, thereby preventing a safety accident that may occur due to the non-occurrence of the clamping force after the driver leaves the vehicle. have.

According to the present invention, a driver can immediately react to an unintentional vehicle flow due to non-occurrence of a clamping force to brake the vehicle, thereby preventing vehicle stability and accidents.

1 is a configuration diagram of an electronic parking brake included in an electronic parking brake system according to an exemplary embodiment.
2 is a control block diagram of an electronic parking brake system according to an exemplary embodiment.
3 is a control flowchart of an electronic parking brake system according to an exemplary embodiment.
4 is a timing diagram illustrating a case in which a failure of the electronic parking brake is suspected and a warning is displayed according to a first preliminary failure detection time during a parking operation in the electronic parking brake system according to the embodiment.
5 is a diagram illustrating a warning of a suspected failure of the electronic parking brake during a parking operation in the electronic parking brake system according to the embodiment.
6 is a timing diagram illustrating a case in which a failure of the electronic parking brake is suspected and a warning is displayed according to a second preliminary failure detection time during a parking operation in the electronic parking brake system according to the embodiment.
7 is a timing diagram illustrating a case in which a failure of the electronic parking brake is suspected and a warning is displayed according to a third preliminary failure detection time during a parking operation in the electronic parking brake system according to the embodiment.

Like reference numerals refer to like elements throughout. This specification does not describe all elements of the embodiments, and general content in the technical field to which the disclosed invention pertains or content overlapping between the embodiments is omitted. The term 'part, module, member, block' used in this specification may be implemented in software or hardware, and according to embodiments, a plurality of 'part, module, member, block' may be implemented as one component, It is also possible for one 'part, module, member, block' to include a plurality of components.

Throughout the specification, when a part is “connected” with another part, it includes not only direct connection but also indirect connection, and indirect connection includes connection through a wireless communication network. do.

In addition, when a part "includes" a certain component, this means that other components may be further included, rather than excluding other components, unless otherwise stated.

Throughout the specification, when a member is said to be located “on” another member, this includes not only a case in which a member is in contact with another member but also a case in which another member exists between two members.

Terms such as 1st, 2nd, etc. are used to distinguish one component from another component, and the component is not limited by the above-mentioned terms. The singular expression includes the plural expression unless the context clearly dictates otherwise.

In each step, the identification code is used for convenience of description, and the identification code does not describe the order of each step, and each step may be performed differently from the specified order unless the specific order is clearly stated in the context. have.

1 is a block diagram of an electronic parking brake included in an electronic parking brake system according to an exemplary embodiment.

Referring to FIG. 1 , the electronic parking brake 10 includes a carrier 110 in which a pair of pad plates 111 and 112 are installed so as to press the brake disk 100 rotating together with the wheel of the vehicle so as to be able to advance and retreat, and the carrier 110 . ) and a caliper housing 120 provided with a cylinder 123 that is slidably installed and the piston 121 is installed so as to move forward and backward by braking hydraulic pressure, a power conversion unit 130 that presses the piston 121, and a motor (M) may include a motor actuator 140 for transmitting the rotational force to the power conversion unit 130 by using.

The pair of pad plates 111 and 112 are to be distinguished into an inner pad plate 111 disposed in contact with the piston 121 and an outer pad plate 112 disposed in contact with the finger portion 122 of the caliper housing 120 . can The pair of pad plates 111 and 112 may be installed on the carrier 110 fixed to the vehicle body so as to move forward and backward toward both sides of the brake disc 100 . Also, a brake pad 113 may be attached to one surface of each of the pad plates 111 and 112 facing the brake disc 100 .

The caliper housing 120 may be slidably installed on the carrier 110 . More specifically, the caliper housing 120 operates the cylinder 123 in which the power conversion unit 130 is installed in the rear part and the piston 121 is built-in to advance and retreat, and the outer pad plate 112 in the front part. It may include a finger portion 122 bent in the downward direction to make it. The finger part 122 and the cylinder 123 may be integrally formed.

The piston 121 is provided in a cylindrical shape with a cup-shaped interior, and can be slidably inserted in the cylinder 123 . The piston 121 may press the inner pad plate 111 toward the brake disc 100 by the axial force of the power conversion unit 130 receiving the rotational force of the motor actuator 140 . Accordingly, when the axial force of the power conversion unit 130 is applied, the piston 121 advances toward the inner pad plate 111 to press the inner pad plate 111, and the caliper housing 120 by the reaction force moves the piston 121 ) and the finger unit 122 presses the outer pad plate 112 toward the brake disc 100 to perform braking.

The power conversion unit 130 may serve to receive the rotational force from the motor actuator 140 and press the piston 121 toward the inner pad plate 111 .

The power conversion unit 130 may include a nut member 131 that is installed to be disposed within the piston 121 and is in contact with the piston 121, and a spindle member 135 screwed to the nut member 131. .

The nut member 131 may be disposed in the piston 121 in a state in which rotation is restricted and may be screwed with the spindle member 135 .

The nut member 131 includes a head portion 132 provided to be in contact with the piston 121 , and a coupling portion 133 extending from the head portion 132 and having a female thread on the inner peripheral surface to be screwed with the spindle member 135 . can be made with

The nut member 131 moves in a forward direction or a reverse direction according to the rotation direction of the spindle member 135 and may serve to pressurize and release the pressure of the piston 121 . In this case, the forward direction may be a movement direction in which the nut member 131 approaches the piston 121 . The backward direction may be a moving direction in which the nut member 131 moves away from the piston 121 . In addition, the forward direction may be a movement direction in which the piston 121 approaches the brake pad 113 . The backward direction may be a moving direction in which the piston 121 moves away from the brake pad 113 .

The spindle member 135 passes through the rear portion of the caliper housing 120 and receives the rotational force of the motor actuator 140 to rotate the shaft portion 136, and the flange portion 137 extending radially from the shaft portion 136. may include One side of the shaft portion 136 may be rotatably installed through the rear side of the cylinder 123 , and the other side may be disposed within the piston 121 . At this time, one side of the shaft portion 136 passing through the cylinder 123 may be connected to the output shaft of the reducer 142 to receive the rotational force of the motor actuator 140 .

The motor actuator 140 may include a motor 141 and a reducer 142 .

The motor 141 may press or release the pressure of the piston 121 by rotating the spindle member 135 to move the nut member 131 forward and backward.

The reducer 142 may be provided between the output side of the motor 141 and the spindle member 135 .

By having the above configuration, the electronic parking brake 10 can press the piston 121 by moving the nut member 131 by rotating the spindle member 135 in one direction using the motor actuator 140 in the parking operation mode. have. The piston 121 pressed by the movement of the nut member 131 presses the inner pad plate 111 to bring the brake pad 113 into close contact with the brake disc 100 , thereby generating a fastening force.

Also, in the electronic parking brake 10 , the nut member 131 pressed to the piston 121 may move backward by rotating the spindle member 135 in the opposite direction using the motor actuator 140 in the parking release mode. The pressure on the piston 121 may be released by the retreating movement of the nut member 131 . When the pressure on the piston 121 is released, the fastening force generated by the brake pad 113 being spaced apart from the brake disc 100 may be released.

2 is a control block diagram of an electronic parking brake system according to an embodiment.

Referring to FIG. 2 , the electronic parking brake system may include an electronic parking brake 10 , an EPB switch 20 , a control unit 30 , a current sensor 40 , and a warning unit 50 .

The electronic parking brake 10 may provide a clamping force, which is a fastening force for parking, to a wheel of a vehicle, for example, a brake disk rotating together with left and right rear wheels.

The electronic parking brake 10 generates a clamping force for each rear wheel. The electronic parking brake 10 is controlled by an electrically connected control unit 30 .

The electronic parking brake 10 is operated by a motor 141 to generate a clamping force. The electronic parking brake 10 generates a clamping force by driving the motor 141 to press the brake pads 113 in the brake caliper housing 120 on the left and right rear wheels to the brake disc 100 .

The EPB switch 20 is a switch for receiving the driver's intention to operate the electronic parking brake 10 , and may be provided near the driver's seat of the vehicle.

The EPB switch 20 is provided to be turned on or off by the driver.

The EPB switch 20 transmits a signal corresponding to a parking operation command (engagement command) to the control unit 30 in an on operation, and a signal corresponding to a parking release command (engagement release command) in an off operation.

The current sensor 40 may be provided to detect a current flowing in the motor 141 of the electronic parking brake 10 . The current sensor 40 may detect a motor current flowing through the motor 141 using a shunt resistor or a Hall sensor. In addition to the shunt resistor or the Hall sensor, the current sensor 40 may use various methods capable of sensing the motor current.

The warning unit 50 may be formed of a warning light, a cluster, or a combination of the two. The warning unit 50 may give a visual, auditory or audiovisual warning to the driver. The warning unit 50 may be provided as a buzzer or a speaker near the brake pedal of the vehicle, may be provided in a portion of the interior of the vehicle, or may be a speaker of a car audio system provided inside the vehicle. The warning unit 50 may warn the driver of a failure of the electronic parking brake 10 or may warn the driver of a suspected failure of the electronic parking brake 10 .

The control unit 30 may engage or disengage the electronic parking brake 10 by an operation signal of the EPB switch 20 or an operation signal generated by a program related to operation of the electronic parking brake.

The control unit 30 determines whether the current motor current reaches the target current during the parking operation, and ends the parking operation control.

The control unit 30 receives power from the battery 60 .

The controller 30 may detect an applied voltage supplied from the battery 60 .

The control unit 30 supplies power provided from the battery 60 to the motor 141 of the electronic parking brake 10 to drive the motor 141 to generate a clamping force. The controller 30 drives the motors 141 of each electronic parking brake 10 to supply and cut off power to these motors M and 141 when generating or releasing the clamping force.

The controller 30 may communicate with various systems mounted on the vehicle through a network bus. As the network bus, Ethernet, Media Oriented Systems Transport (MOST), Flexray, CAN (Controller Area Network; CAN), LIN (Local Interconnect Network), etc. may be used.

The controller 30 may communicate with various systems mounted on the vehicle to receive various vehicle state information such as transmission location information, starting information, and brake hydraulic pressure information. The transmission position information indicates whether the position of the transmission is P (parking), R (reverse), N (neutral), and D (driving). The starting information indicates whether the vehicle is in an ignition-on state or an ignition-off state. The brake hydraulic pressure information indicates the pressure of the cylinder 123 of the electronic parking brake 10 . The control unit 30 may directly detect transmission position information, starting information, and brake hydraulic pressure information.

The controller 30 may drive the motor 141 of the electronic parking brake 10 . The controller 30 may drive the motor 141 in a forward rotation direction or a reverse rotation direction. For example, the control unit 30 may include an H-bridge circuit including a plurality of power switching elements to drive the motor 141 in a forward rotation direction or a reverse rotation direction.

The controller 30 may drive the motor 141 by a manipulation signal of the EPB switch 20 operated by the driver or a manipulation signal generated by a program related to the operation of the electronic parking brake.

The control unit 30 may perform a parking operation mode or a parking release mode according to an operation signal of the EPB switch 20 operated by the driver or an operation signal generated by a program related to operation of the electronic parking brake.

The control unit 30 determines whether the electronic parking brake 10 is in a malfunctioning state during a parking operation, and if it is in a malfunctioning state, warns the driver of the failure of the electronic parking brake 10 through the warning unit 50 .

The control unit 30 determines whether the electronic parking brake 10 is in a suspected failure state during the parking operation, and when in a suspected failure state, warns the driver of the suspected failure of the electronic parking brake 10 through the warning unit 50 .

The controller 30 may include a processor 31 and a memory 32 .

The processor 31 includes a digital signal processor for processing an EPB switch signal, motor current, battery voltage, transmission position information, starting information, brake hydraulic information, and the like, and a motor driving for parking operation or release of the electronic parking brake 10 . It may include a micro control unit (MCU) that generates a signal.

The memory 32 includes a program and/or data for the processor 31 to process information such as EPB switch signal, motor current, battery voltage, transmission position information, starting information, and brake hydraulic pressure information, and the processor 31 electronically It is possible to store a program and/or data for generating a motor drive signal for parking operation or parking release of the parking brake 10 .

The memory 32 temporarily stores information such as EPB switch signal, motor current, battery voltage, transmission position information, starting information, and brake hydraulic pressure information, and the EPB switch signal of the processor 31, motor current, battery voltage, transmission The processing result of information such as position information, starting information, and brake hydraulic pressure information can be temporarily stored.

The memory 32 includes not only volatile memories such as S-RAM and D-RAM, but also flash memory, read-only memory (ROM), erasable programmable read-only memory (EPROM), etc. of non-volatile memory.

3 is a control flowchart of an electronic parking brake system according to an embodiment.

Referring to FIG. 3 , first, the control unit 30 determines whether a parking operation condition is satisfied ( 200 ). The control unit 30 may determine that the parking operation condition is satisfied when the EPB switch 20 is in an on state or when the transmission is stopped at the P stage.

When the parking operation condition is satisfied, the controller 30 performs the parking operation ( 202 ). The control unit 30 drives the motor 141 of the electronic parking brake 10 for parking operation. When the electronic parking brake 10 is in a normal state rather than a failure state, the spindle member 135 rotates in one direction by rotating the motor 141 in the parking operation direction. The nut member 131 is moved by the rotation of the spindle member 135 , and the piston 121 is pressed by the movement of the nut member 131 . As the pressurized piston 121 presses the inner pad plate 111 , the brake pad 113 is in close contact with the brake disc 100 to generate a clamping force.

The control unit 30 detects a current of the motor 141 through the current sensor 40 after parking the electronic parking brake 10 ( 204 ).

The controller 30 determines whether the motor current is less than the load current Iload (206). The load current Iload is the motor current value when the clamping force starts to occur. If the motor current is less than the load current (Iload), the clamping force is not generated. If the motor current is not less than the load current Iload, the clamping force is occurring.

When the motor current is less than the load current Iload (206, YES), the control unit 30 counts a time during which the clamping force is not generated and the clamping force is not generated (208).

The control unit 30 determines whether the clamping force non-occurrence time is less than the failure detection time (210). The failure detection time is a preset time for detecting a failure of the electronic parking brake. In the case of the electronic parking brake 10, in the normal state, the motor current exceeds the load current (Iload) and reaches the target current before the failure detection time elapses. The load current Iload or the target current (current value higher than the load current) cannot be reached.

If the clamping force non-occurrence time is not less than the failure detection time (210, No), the control unit 30 stops the driving motor 141 to stop the parking operation (212), and the warning unit 50 It warns the driver of the failure of the electronic parking brake 10 through the operation 214 .

On the other hand, when the clamping force non-occurrence time is less than the failure detection time (210, Yes), the control unit 30 determines whether the clamping force non-occurrence time is greater than the preliminary failure detection time (216). The preliminary fault detection time is set shorter than the fault detection time. The preliminary failure detection time is a time during which the clamping force must be generated when the electronic parking brake 10 is in a normal state.

If the clamping force non-occurrence time is not longer than the preliminary failure detection time (216, NO), the control unit 30 moves to the operation mode 202 and performs the following operation modes.

On the other hand, when the clamping force non-occurrence time is longer than the preliminary failure detection time (216, Yes), the controller 30 suspects the failure of the electronic parking brake 10 (218). Although the clamping force has not occurred, the control unit 30 suspects the failure of the electronic parking brake 10 because it is still too early to determine the failure.

The control unit 30 warns the driver of the suspected failure of the electronic parking brake 10 through the warning unit 50 (220). Therefore, it is possible to prevent the driver from leaving the vehicle until the failure determination of the electronic parking brake 10 is completed, thereby preventing a safety accident that may occur due to non-occurrence of the clamping force after the driver leaves the vehicle. have. In addition, the driver can immediately react to the unintentional vehicle flow due to non-occurrence of the clamping force to brake the vehicle, thereby preventing vehicle safety and accidents.

4 is a timing diagram illustrating a case in which a failure of the electronic parking brake is suspected and a warning is displayed according to a first preliminary failure detection time during a parking operation in the electronic parking brake system according to the embodiment.

Referring to FIG. 4 , the driving of the motor 141 is started according to the request for parking operation, and the operation process is determined by detecting a motor current generated during the operation of the motor, and finally it is determined whether the operation is completed.

The parking operation section can be largely divided into three parts according to the characteristics of the change in the current value. When a current is initially input to the motor 141, a large amount of current is needed instantaneously because of the inertia to continue to stand still. Therefore, there is a part where the current rapidly increases, which is called an in-rush current (Irsh). Thereafter, while the motor 141 rotates, the brake pad 113 is pushed in the direction of the brake disc 100 . Since there is no load other than the weight of the brake pad 113 , it is called a no-load section. Finally, the process of generating a clamping force while the brake pad 113 comes into contact with the brake disc 100 and compresses it to a target current is referred to as a load section.

The end point of the parking operation function is the point at which the load section lasts to some extent and sufficient clamping force is generated to park the vehicle. The current value is preset.

In FIG. 4 , the horizontal axis represents time and the vertical axis represents the motor current.

The failure detection time is t1 to t3.

The first preliminary failure detection time t1-t2 is set shorter than the failure detection time. The first preliminary failure detection time t1 - t2 is a preset time and ranges from t1 to t2.

The load current Iload is the motor current value when the clamping force starts to occur.

The no-load current Iidle is a motor current value in the no-load section.

The first preliminary failure detection time t1-t2 is set longer than the time of the no-load section in the normal state.

Since the motor current maintains the no-load current Iidle lower than the load current Iload during t1 to t2, the clamping force is not generated during the first preliminary failure detection time t1 to t2. This is a state in which the actual clamping force is not generated in the section where the clamping force starts to be generated due to mechanical damage of the reduction gear of the electronic parking brake 10 or the mechanical structure device.

In this case, it is suspected that the electronic parking brake 10 is malfunctioning and warns of a possible malfunction. The driver can prevent the driver from leaving the vehicle until the failure judgment is completed by this malfunction warning warning.

5 is a diagram illustrating a warning of a suspected failure of the electronic parking brake during a parking operation in the electronic parking brake system according to the embodiment.

The control unit 30 warns the driver through the warning unit 50 that the electronic parking brake 10 is in a suspected malfunction state.

The control unit 30 warns the driver visually and/or audible that the electronic parking brake 10 is in a suspected failure state through the combination of the warning light 51 and the speaker 52 of the warning unit 50, so that the driver determines the failure Do not leave the vehicle until this is complete.

Referring again to FIG. 4 , if the clamping force does not occur during the failure detection time (t1 to t3) after the failure suspected warning, the failure is confirmed and the failure of the electronic parking brake 10 is warned.

On the other hand, the preliminary failure detection time is not set in advance like the first preliminary failure detection time, and may be determined based on the time for determining the completion of parking release at the time of previous parking release. The parking release completion determination time may be set based on the no-load duration.

6 is a timing diagram illustrating a case in which a failure of the electronic parking brake is suspected and a warning is displayed according to a second preliminary failure detection time during a parking operation in the electronic parking brake system according to the embodiment.

Referring to FIG. 6 , the second preliminary failure detection time t1 - t2 may be a determination time of parking release completion when parking is released. When the parking release is completed during the previous parking release, the parking release completion determination time t1-t2 is stored in the memory 32 . In this case, the parking release completion determination time may be compensated according to the battery voltage and/or the brake hydraulic pressure. For example, as the battery voltage is lower, the motor 141 rotates slowly and the no-load time becomes longer, so that the lower the battery voltage, the longer the parking release completion determination time can be compensated. In addition, as the brake hydraulic pressure, which is the pressure of the cylinder 123 of the electronic parking brake 10, increases, the moving distance of the nut member 131 increases in the no-load section, so that the parking release completion determination time t1-t2 is longer. can

In this state, the second preliminary failure detection time (t1-t2) is set to the parking release completion determination time (t1-t2) stored in the memory 32 during the parking operation, and this second preliminary failure detection time (t1-t2) Based on this, the failure of the electronic parking brake 10 is suspected.

The second preliminary failure detection time t1 - t2 may be set based on a time point at which the motor current is decreased to be lower than the load current Iload or a time point at which the motor current is decreased to a no-load current Iidle.

Since the motor current maintains the no-load current Iidle lower than the load current Iload during t1 to t2, the clamping force is not generated during the second preliminary failure detection time t1 to t2.

In this case, it is suspected that the electronic parking brake 10 is malfunctioning and warns of a possible malfunction. The driver can prevent the driver from leaving the vehicle until the failure judgment is completed by this malfunction warning warning.

If the clamping force does not occur during the failure detection time (t1 to t3) after the failure suspected warning, the failure is confirmed and a failure of the electronic parking brake 10 is warned.

7 is a timing diagram illustrating a case in which a failure of the electronic parking brake is suspected and a warning is displayed according to a third preliminary failure detection time during a parking operation in the electronic parking brake system according to the embodiment.

Referring to FIG. 7 , the third preliminary failure detection time t1-t2 is determined based on the parking release completion determination time T1-T2 when parking is released, and the battery voltage and brake hydraulic pressure during parking operation.

The third preliminary failure detection time t1-t2 is based on the parking release completion determination time T1-T2, and is compensated according to the battery voltage and brake hydraulic pressure during parking operation.

The lower the battery voltage, the longer the no-load time because the motor 141 rotates slowly. Accordingly, the third preliminary failure detection time is compensated to be longer as the battery voltage is lowered.

As the brake hydraulic pressure, which is the pressure of the cylinder 123 of the electronic parking brake 10, increases, the moving distance of the nut member 131 increases in the no-load section, so that the third preliminary failure detection time is compensated for longer.

The third preliminary failure detection times t1 to t2 may be set based on a time point at which the motor current is reduced to be lower than the load current Iload or a time point at which the no-load current Iidle is decreased.

Since the motor current maintains the no-load current Iidle lower than the load current Iload during t1 to t2, the clamping force is not generated during the third preliminary failure detection time t1 to t2.

In this case, it is suspected that the electronic parking brake 10 is malfunctioning and warns of a possible malfunction. The driver can prevent the driver from leaving the vehicle until the failure judgment is completed by this malfunction warning warning.

If the clamping force does not occur during the failure detection time (t1 to t3) after the failure suspected warning, the failure is confirmed and a failure of the electronic parking brake 10 is warned.

As described above, in the present invention, when the clamping force does not occur, the driver prevents the driver from leaving the vehicle until the failure determination is completed, thereby preventing a safety accident that may occur due to the non-occurrence of the clamping force after the driver leaves the vehicle. can be prevented in In addition, according to the present invention, the driver can immediately react to the unintentional vehicle flow due to non-occurrence of the clamping force to brake the vehicle, thereby preventing vehicle safety and accidents.

Meanwhile, in the above embodiments, although the motor-on-caliper type electronic parking brake has been described, it is not limited thereto, and a drum rotating together with the wheel is provided therein and the brake lining is attached thereto. An electric drum brake that a pair of brake shoes expands and brakes is also possible.

In addition, although the foregoing embodiments have been described with respect to an electronic parking brake system having a motor-on-caliper type electronic parking brake or an electric drum brake, the present invention is not limited thereto. The electronic parking brake system may be an electromechanical brake system that performs a parking brake function that maintains a stop state of the vehicle when parking in addition to a service brake function that provides braking force in a driving situation of the vehicle.

10: Electronic parking brake 20: EPB switch
30: control unit 31: processor
32: memory 40: current sensor
50: warning unit 60: battery

Claims (15)

an electronic parking brake that provides a clamping force necessary for parking the vehicle by means of a motor;
a warning unit warning the failure of the electronic parking brake;
a current sensor detecting the current of the motor; and
A control unit electrically connected to the current sensor,
The control unit determines whether a clamping force is generated according to a motor current during parking operation, and if the clamping force does not occur, counts a time when the clamping force does not occur, and the time when the clamping force does not occur is a failure detection of the electronic parking brake An electronic parking brake system that warns of a possible failure of the electronic parking brake through the warning unit when a preliminary failure detection time set shorter than the time elapses. According to claim 1,
The control unit is an electronic parking brake system for determining the preliminary failure detection time as a preset time. According to claim 1,
The control unit is an electronic parking brake system for determining the preliminary failure detection time based on the parking release completion determination time for determining the parking release completion at the time of the previous parking release. 4. The method of claim 3,
The control unit is an electronic parking brake system for storing the parking release completion determination time in a memory when the previous parking is released. 5. The method of claim 4,
The control unit compensates the parking release completion determination time by at least one of a battery voltage and a brake hydraulic pressure at the time of previous parking release. According to claim 1,
The control unit is an electronic parking brake system for determining the preliminary failure detection time based on a parking release completion determination time for determining the parking release completion at the time of previous parking release, and a battery voltage and brake hydraulic pressure during the parking operation. 7. The method of claim 6,
The control unit compensates for the preliminary failure detection time so that the preliminary failure detection time becomes longer as the battery voltage is lowered. 7. The method of claim 6,
The control unit compensates for the preliminary failure detection time so that the preliminary failure detection time becomes longer as the brake hydraulic pressure increases. A method for controlling an electronic parking brake for controlling an electronic parking brake that provides a clamping force necessary for parking a vehicle by a motor, the method comprising:
Detecting the current of the motor during parking operation, determining whether a clamping force is generated according to the detected motor current,
If the clamping force does not occur, count the time when the clamping force does not occur,
and warning a suspected failure of the electronic parking brake when a preliminary failure detection time set shorter than a failure detection time of the electronic parking brake has elapsed when the clamping force non-occurrence time period is shorter than the failure detection time of the electronic parking brake. 10. The method of claim 9,
Warning of a possible failure of the electronic parking brake is,
and determining the preliminary failure detection time as a preset time. 10. The method of claim 9,
Warning of a possible failure of the electronic parking brake is,
A control method of an electronic parking brake system for determining the preliminary failure detection time based on the parking release completion determination time for determining the parking release completion during the previous parking release. 12. The method of claim 11,
The control method of the electronic parking brake system further comprising storing the parking release completion determination time in a memory when the previous parking is released. 10. The method of claim 9,
Warning of a possible failure of the electronic parking brake is,
A control method of an electronic parking brake system, comprising: determining the preliminary failure detection time based on a parking release completion determination time for determining the parking release completion in the previous parking release, and a battery voltage and brake hydraulic pressure during the parking operation . 14. The method of claim 13,
To determine the preliminary failure detection time,
and compensating for the preliminary failure detection time so that the preliminary failure detection time becomes longer as the battery voltage decreases. 14. The method of claim 13,
To determine the preliminary failure detection time,
and compensating for the preliminary failure detection time so that the preliminary failure detection time becomes longer as the brake hydraulic pressure increases.

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