Electronic parking brake system and method of controlling the same

Provided is an electronic parking brake system including: an electronic parking brake provided in at least one of a front wheel and a rear wheel of a vehicle and driven by a motor; and a controller electrically connected to the motor, wherein the controller is configured to determine whether a gear stage of an electronic transmission system (a shift by wire: SBW) is shifted to a neutral position during ignition-off of the vehicle, and upon determining that the gear stage is shifted to the neutral position, release engagement of the electronic parking brake.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based on and claims priority under 35 U.S.C. § 119 to Korean Patent Application No. 10-2021-0103706, filed on Aug. 6, 2021 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.

BACKGROUND

The present disclosure relates to an electronic parking brake system and a method of controlling the same.

2. Description of the Related Art

In general, when a parking lot does not have enough parking space, double parking frequently occurs while blocking fronts of other vehicles.

In the case of double parking, the driver of the vehicle blocked on the front by the double-parked vehicle manually pushes and moves the double-parked vehicle to secure an exit space and then departs. To this end, the driver of the double-parked vehicle performs neutral parking by putting a transmission gear from a parking (P) position to a neutral (N) position.

There are some vehicles in which neutral parking is not performable.

In the case of vehicles equipped with an electronic transmission (a shift by wire: SBW) and an electronic parking brake (EPB), when the engine is turned off, the gear stage is automatically shifted to parking (P), and the EPB is automatically engaged. In the SBW, the shift of gear stages (P-R-N-D) is electronically performed.

Such vehicles, in which neutral parking is not performable, have no choice but to park in a state of the inability to park in neutral, and the driver of the vehicle blocked by the double parking may have inconvenience in calling the driver of the double parked vehicle to the parking lot.

SUMMARY

Therefore, it is an object of the disclosure to provide a provides an electronic parking brake system capable of realizing neutral parking based on shifting of the gear stage to neutral during parking to release engagement of an electronic parking brake, and a method of controlling the same.

The technical objectives of the disclosure are not limited to the above, and other objectives may become apparent to those of ordinary skill in the art based on the following descriptions.

According to an aspect of the disclosure, there is provided an electronic parking brake system including: an electronic parking brake provided in at least one of a front wheel and a rear wheel of a vehicle and driven by a motor; and a controller electrically connected to the motor, wherein the controller is configured to determine whether a gear stage of an electronic transmission system (a shift by wire: SBW) is shifted to a neutral position during ignition-off of the vehicle, and upon determining that the gear stage is shifted to the neutral position, release engagement of the electronic parking brake.

The controller may be configured to determine whether the gear stage is shifted to a neutral position during ignition-off of the vehicle, of which the gear stage automatically shifts to a parking position and the electronic parking brake is automatically engaged in response to switching to ignition-off.

The controller may be configured to switch from a sleep mode to a wake-up mode by an N-stage signal received from the electronic transmission system, and determine whether the gear stage is shifted to a neutral position during ignition-off of the vehicle in the wake-mode.

The controller may be connected to an N-stage switch of the electronic transmission system with a signal line, and receive the N-stage signal generated when the N-stage switch is turned on by a driver through the signal line.

The controller may be configured to, upon determining that the vehicle is in an ignition-off state and a gear stage signal received from the electronic transmission system is the N-stage signal in the wake-up mode, determine that the gear stage is shifted to the neutral position during ignition-off of the vehicle.

The controller may be configured to, upon determining that the vehicle is in an ignition-off state, a gear stage signal received from the electronic transmission system is the N-stage signal, and a brake pedal is in operation in the wake-up mode, determine that the gear stage is shifted to the neutral position during ignition-off of the vehicle.

The controller may be configured to, upon determining that the gear stage is shifted to the neutral position, determine whether the electronic parking brake is engaged, and upon determining that the electronic parking brake is engaged, release the engagement of the electronic parking brake.

The controller may be configured to, upon completion of the releasing of the engagement of the electronic parking brake, switch from a wake-up mode to a sleep mode.

According to another aspect of the disclosure, there is provided a method of controlling an electronic parking brake system including an electronic parking brake provided in at least one of a front wheel and a rear wheel of a vehicle and driven by a motor, the method including: determining whether a gear stage of an electronic transmission system (a shift by wire: SBW) is shifted to a neutral position during ignition-off of the vehicle; and upon determining that the gear stage is shifted to the neutral position, releasing engagement of the electronic parking brake.

The determining of whether the gear stage is shifted to the neural position may include determining whether the gear stage is shifted to a neutral position during ignition-off of the vehicle, of which the gear stage automatically shifts to a parking position and the electronic parking brake is automatically engaged in response to switching to an ignition-off state.

The determining of whether the gear stage is shifted to the neural position may include switching from a sleep mode to a wake-up mode by a N-stage signal received from the electronic transmission system, and determining whether the gear stage is shifted to a neutral position during ignition-off of the vehicle in the wake-mode.

The determining of whether the gear stage is shifted to the neural position may include receiving the N-stage signal that is generated when an N-stage switch of the electronic transmission system is turned on by a driver.

The determining of whether the gear stage is shifted to the neural position may include, upon determining that the vehicle is in an ignition-off state and a gear stage signal received from the electronic transmission system is the N-stage signal in the wake-up mode, determining that the gear stage is shifted to the neutral position during ignition-off of the vehicle.

The determining of whether the gear stage is shifted to the neural position may include, upon determining that the vehicle is in an ignition-off state, a gear stage signal received from the electronic transmission system is the N-stage signal, and a brake pedal is in operation in the wake-up mode, determining that the gear stage is shifted to the neutral position during ignition-off of the vehicle.

The releasing of the engagement of the electronic parking brake may include, upon determining that the gear stage is shifted to the neutral position, determining whether the electronic parking brake is engaged, and upon determining that the electronic parking brake is engaged, releasing the engagement of the electronic parking brake.

The releasing of the engagement of the electronic parking brake may include, upon completion of the releasing of the engagement of the electronic parking brake, switching from a wake-up mode to a sleep mode.

DETAILED DESCRIPTION

Like numerals refer to like elements throughout the specification. Not all elements of embodiments of the present disclosure will be described, and description of what are commonly known in the art or what overlap each other in the embodiments will be omitted. The terms as used throughout the specification, such as “˜part”, “˜module”, “˜member”, “˜block”, etc., may be implemented in software and/or hardware, and a plurality of “˜parts”, “˜modules”, “˜members”, or “˜blocks” may be implemented in a single element, or a single “˜part”, “˜module”, “˜member”, or “˜block” may include a plurality of elements.

In the specification, it will be understood that, when a member is referred to as being “on/under” another member, it may be directly on/under the other member, or one or more intervening members may also be present.

Although the terms “first,” “second,” “A,” “B,” etc. may be used to describe various components, the terms do not limit the corresponding components, but are used only for the purpose of distinguishing one component from another component. As used herein, the singular forms “a,” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise.

FIG.1is a diagram illustrating a vehicle to which an electronic parking brake system according to an embodiment is applied.

Referring toFIG.1, a vehicle may include an electronic transmission system10and an electronic parking brake system20.

The electronic transmission system10is a shifting system provided for convenience of shifting, in which when the driver presses an electronic shift button, or slightly pushes and pulls an electronic shift lever, an electrical signal is transmitted to a transmission such that a gear stage is shifted and the travel function is converted.

The electronic parking brake system20may communicate with the electronic transmission system10through a vehicle communication network NT. For example, the systems may transmit data through Ethernet, Media Oriented Systems Transport (MOST), Flexray, Controller Area Network (CAN), Local Interconnect Network (LIN), and the like.

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

Referring toFIG.2, the electronic parking brake system20may include two electronic parking brakes100, a controller200, and an EPB switch300.

The first and second electronic parking brakes (the first EPB and the second EPB)100may be mounted on rear wheels of the vehicle. The EPB may be installed for each wheel.

The EPB switch300receives an intention to engage the EPB or an intention to release engagement of the EPB from the driver.

The controller200receives an EPB switch signal indicating the intention to engage the EPB or the intention to release the engagement of the EPB from the EPB switch300.

The controller200controls the first and second EPBs100to engage or disengage the first and second EPBs100.

The controller200is communicatively connected to a shift by wire (SBW) controller11that performs overall control of the electronic transmission system10.

The SBW controller11receives a shift signal input from a shift manipulator12capable of electronically shifting between a P-stage (parking), an R-stage (reverse), an N-stage (neutral), and a D-stage (forward), and performs shift control according to the received shift signal. The shift manipulator12may be provided in various types, such as a button type, a lever type, or a mixture thereof. The SBW controller11may perform shift control by driving a solenoid or an electric motor according to a gear stage input of the shift manipulator12to apply or block hydraulic pressure for each gear stage.

The controller200may transmit and receive information to and from the SBW controller11through, for example, CAN communication.

The controller200may receive an ignition signal (an IGN signal) indicating an ignition state of the vehicle and a brake pedal signal indicating an operating state of a brake pedal. The controller200may receive the brake pedal signal from a brake pedal sensor that detects an operating state of the brake pedal, or may receive the brake pedal signal from another system through CAN communication.

As described above, in a vehicle equipped with an electronic transmission and an EPB, when ignition is turned off, the gear stage is automatically shifted to the P-stage, and the EPB is automatically engaged.

In this case, the controller200is switched to a sleep mode to save power. Accordingly, the controller200is neither able to wake up nor able to perform CAN communication with the SBW controller11, so that the EPB cannot be disengaged and neutral parking is not performable.

In order to solve the constraints, the controller200may, when the gear stage of the electronic transmission system10is shifted to the N-stage by the driver during ignition-off, release the engagement of the EPB100. With the shifting of the gear stage to the neutral position, the EPB100is allowed to be released from engagement, so that neutral parking is implemented.

The controller200is connected to an N-stage switch12aof the electronic transmission system10by a signal line SL. The controller200may receive an N-stage signal generated when the N-stage switch12ais turned on by the driver through the separate signal line SL even during the ignition-off of the vehicle. During ignition-off, power supply to all systems including the electronic transmission system10is cut off, and in response to the driver pressing the brake pedal, the electronic transmission system10may be supplied with operating power.

The controller200switches from a sleep mode to a wake-up mode by the N-stage signal, in response to receiving the N-stage signal of the electronic transmission system10during ignition-off. The sleep mode is a state in which, subsequent to the ignition of the vehicle being switched to an off stat, CAN communication is inoperable and a minimum current is consumed to prevent battery discharge, and operating power (wake-up power) is not be supplied to a processor that perform the overall control in the controller200. The wakeup mode is a normal driving mode, which is a state after a wake-up signal is received in a sleep mode.

The controller200, in response to switching to the wake-up mode, determines whether the vehicle is in an ignition-off state from an ignition signal (IGN signal) and the brake pedal is in operation from a brake pedal signal. The controller200, if a result of the determination is that the vehicle is in an ignition-off state and the brake pedal is in operation, outputs a parking release command for releasing the engagement of the EPB100to the EPB100.

FIG.3is a block diagram illustrating a configuration of an electronic parking brake (EPB) applied to an electronic parking brake system according to an embodiment.

Referring toFIG.3, the EPB100includes a carrier110in which a pair of pad plates111and112are reciprocatingly installed so as to press a brake disk D rotating together with the wheel of the vehicle, a caliper housing120slidably installed in the carrier110and provided with a cylinder123in which a piston121is installed so as to advance and retreat by braking hydraulic pressure, a power conversion unit130that presses the piston121, and a motor actuator140for transmitting a rotational force to the power conversion unit130using a motor M.

The pair of pad plates111and112are divided into an inner pad plate111disposed to be in contact with the piston121and an outer pad plate112disposed to be in contact with a finger portion122of the caliper housing120. The pair of pad plates111and112are installed on the carrier110fixed to the vehicle body so as to advance and retreat toward both sides of the brake disc D. In addition, each of the pad plates111and112has one surface facing the brake disk D to which a brake pad113is attached.

The caliper housing120is slidably installed on the carrier110. More specifically, the caliper housing120is provided at a rear side with the power conversion unit130, and includes the cylinder123in which the piston121is built-in to advance and retreat, and a finger portion122formed on a front side and bent in the downward direction to operate the outer pad plate112. The finger portion122is integrally formed with the cylinder123.

The piston121is provided in the form of a cylinder with a cup-shaped interior and is slidably inserted in the cylinder123. The piston121presses the inner pad plate111toward the brake disk D by the axial force of the power conversion unit130receiving the rotational force of the motor actuator140. Accordingly, in response to receiving the axial force of the power conversion unit130, the piston121advances toward the inner pad plate111to press the inner pad plate111, and the reaction force causes the caliper housing120to operate in the opposite direction to the piston121such that the finger portion122presses the outer pad plate112toward the brake disc D, thereby performing braking.

The power conversion unit130may serve to receive the rotational force from the motor actuator140to press the piston121toward the inner pad plate111.

The power conversion unit130may include a nut member131that is disposed inside the piston121to be in contact with the piston121, and a spindle member135screwed to the nut member131.

The nut member131may be disposed inside the piston121in a state in which rotation is restricted, and screw-coupled to the spindle member135.

The nut member131may include a head portion132provided to be in contact with the piston121, and a coupling portion133extending from the head portion132and having a female thread on the inner circumferential surface thereof so as to be screwed with the spindle member135.

The nut member131moves in a forward direction or a reverse direction according to the rotation direction of the spindle member135to press the piston121and release the pressure of the piston121. In this case, the forward direction may be a direction in which the nut member131moves toward the piston121. The backward direction may be a direction in which the nut member131moves away from the piston121. In addition, the forward direction may be a direction in which the piston121moves toward the brake pad113. The backward direction may be a direction in which the piston121moves away from the brake pad113.

The spindle member135may include a shaft portion136passing through the rear portion of the caliper housing120and rotating based on receiving the rotational force of the motor actuator140and a flange portion137extending radially from the axial portion136. The shaft portion136may have one side passing through the rear side of the cylinder123and rotatably installed, and the other side disposed inside the piston121. In this case, the one side of the shaft portion136passing through the cylinder123is connected to an output shaft of a reducer142to receive the rotational force of the motor actuator140.

The motor actuator140may include an electric motor141and a reducer142.

The electric motor141may rotate the spindle member135to move the nut member131forward and backward to press the piston121or release the pressure of the piston121.

The reducer142may be provided between the output side of the electric motor141and the spindle member135.

With such a configuration, the EPB, in a parking apply mode, may rotate the spindle member135in one direction using the motor actuator140to move the nut member131to thereby press the piston121. The piston121pressed by the movement of the nut member131presses the inner pad plate111to bring the brake pad113into close contact with the brake disc D, thereby generating a clamping force.

In addition, the EPB, in a parking release mode, may rotate the spindle member135in the opposite direction using the motor actuator140to cause the nut member1131pressed by the piston121to move backward. The backward movement of the nut member131causes the pressure on the piston121to be released. By the pressure on the piston121being released, the brake pad113moves away from the brake disc D such that the generated clamping force is released.

FIG.4is a diagram illustrating a detailed configuration of a controller of an electronic parking brake system according to the embodiment.

Referring toFIG.4, the controller200may be referred to as an electronic control unit (ECU).

The controller200may include a processor210, a memory220, a voltage regulator230, and first and second motor driving units240.

The processor210may control the overall operation of the EPB system.

The memory220may store a program required for the processor210to perform processing or controlling and various types of data for operation of the EPB system.

The memory220may include not only volatile memories, such as an S-RAM and a D-RAM, but also of non-volatile memories, such as flash memories, read-only memories (ROM), erasable programmable read only memories (EPROMs), and the like.

The voltage regulator230may receive an ignition signal (an IGN signal), an EPB switch signal, and an N-stage signal.

The voltage regulator230, in response to one of the ignition signal (the IGN signal), the EPB switch signal, and the N-stage signal being received, supplies the processor210with wake-up power, which is operating power, to wake up the processor210.

The processor210, in response to the wake-up power being applied from the voltage regulator230, switches from a sleep mode to a wake-up mode.

The processor210together with the voltage regulator230may receive an ignition signal (an IGN signal), an EPB switch signal, and an N-stage signal. The processor210may determine whether the vehicle is in an ignition-on state or an ignition-off state according to the ignition signal (the IGN signal). The processor210may determine whether the driver intends to engage or release engagement of the EPB100according to the EPB switch signal. The processor210may determine whether the driver has manipulated the gear stage of the electronic transmission system10to the N-stage based on the N-stage signal.

The processor210may receive a brake pedal signal.

The first and second motor driving units240drive the electric motors141of the first and second EPBs100under the control of the processor210to perform an engagement operation for generating a clamping force in the first and second EPBs100or perform a disengagement operation for releasing the generated clamping force.

FIG.5is a diagram illustrating a control timing of an electronic parking brake system according to the embodiment.

Referring toFIG.5, when the ignition of the vehicle is switched from an on-state to an off-state at a time t1, the EPB100starts to be engaged at the time t1and the engagement is completed at a time t2.

In this state, if the driver manipulates the N-stage among the shift buttons of the electronic transmission system10for neutral parking during the ignition-off state, in which the ING signal indicate an off-state, the N-stage signal is set into an on-state, and the N-stage signal allows the processor210to be supplied with operating power from the voltage regulator230, so that the sleep mode is switched to the wake-up mode.

The processor210releases the engaged EPB100if the N-stage signal is in an on-state, the ignition is in an off-state, and the brake pedal is operation at a t3when which the processor210is switched to a wake-up state.

The processor210, at a time t4when the release of the engagement of the EPB100is completed, is switched from the wakeup mode back to the sleep mode.

FIG.6is a flow chart showing a method of controlling an electronic parking brake system according to an embodiment.

Referring toFIG.6, the method of controlling the EPB system according to the embodiment may include determining whether the operation mode is switched from a sleep mode to a wake-up mode (400), determining whether the vehicle is in an ignition-off state (402), determining whether an N-stage signal is received (404), determining whether the brake pedal is in operation (406), determining whether the EPB is engaged (408), releasing engagement of the EPB (410), determining whether the release of the engagement of the EPB is completed (412), and switching from a wakeup mode to a sleep mode (414).

The processor210determines whether the operation mode is switched from a sleep mode to a wake-up mode. The processor210is switched from a sleep mode to a wake-up mode based on receiving wake-up power from the voltage regulator230. The voltage regulator230supplies wake-up power to the processor210in response to receiving an ignition signal (an IGN signal), an EPB switch signal, or an N-stage signal of the electronic transmission system10.

The processor210, in response to switch from the sleep mode to the wake-up mode, determines whether the N-stage signal of the electronic transmission system10is received. This is to determine whether the switch from the sleep mode to the wakeup mode is caused by the N-stage signal.

The processor210, upon determining whether the N-stage signal is received, determines whether the brake pedal is in operation from the brake pedal signal.

The processor210determines whether the EPB100is engaged.

The processor210, upon determining that the EPB100is engaged, releases the engagement of the EPB100through the first and second motor driving units240.

The processor210determines whether the release of the engagement of the EPB100is completed. The processor210may determine whether the release of the engagement of the EPB100is completed using a position sensor of the electric motor141in the EPB100.

The processor210may, in response to the release of the engagement of the EPB100being completed, switch from the wake-up mode back to the sleep mode.

As described above, the EPB system according to the embodiment may release the engagement of the EPB based on shifting of Othe gear stage to a neutral position during parking, thereby implementing neutral parking.

Meanwhile, the above described controller and/or components thereof may include one or more processors/microprocessors combined with a computer-readable recording medium that stores computer-readable code/algorithm/software. The processor (s)/microprocessor(s) may execute the computer-readable code/algorithm/software stored in the computer-readable recording medium to perform the above-described functions, operations, steps, and the like.

The above-described controller and/or components thereof may further include a memory implemented as a computer-readable non-transitory recording medium or a computer-readable transitory recording medium. The memory may be controlled by the above described controller and/or components thereof, and may be configured to store data transmitted to or received from the above described controller and/or components, or store data processed or to be processed by the above described controller and/or components thereof.

The disclosed embodiment can be implemented as a computer-readable code/algorithm/software in a computer readable medium. The computer-readable medium may include a non-transitory computer readable recording medium, such as a data storage device that store data that can be read by a processor/microprocessor. Examples of computer-readable recording media include a Hard Disk Drive (HDD), a Solid State Disk (SSD), a Silicon Disk Drive (SDD), a read-only memory (ROM), a random access memory (RAM), a compact disc read only memory (CD-ROM), a magnetic tape, a floppy disk, an optical data storage device, etc.

As is apparent from the above, the electronic parking brake system according to the present disclosure and the method of controlling the same can realize neutral parking based on shifting of the gear stage to neutral during parking to release engagement of an electronic parking brake.