ELECTRONIC BRAKE SYSTEM, VEHICLE INCLUDING THE SAME, AND METHOD OF OPERATING THE SAME

An electronic brake system is disclosed. According to one aspect of the present disclosure, there may be provided an electronic brake system including a piston provided in a caliper housing to press a pad plate, a nut coupled to the inside of the piston to move the piston forward or backward, a spindle configured to move the nut forward or backward by rotation and including a stepped portion formed on an outer surface thereof, a rotation limit unit connected to or disconnected from the spindle to allow or block the rotation of the spindle, and a drive unit configured to move the rotation limit unit to a position at which the rotation of the spindle is allowed or blocked, wherein the rotation limit unit includes a body surrounding an outer circumferential surface of the spindle, a binder provided on the body and provided to come into close contact with the stepped portion, and a connector provided on the body and configured to receive a driving force from the drive unit.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based on and claims priority under 35 U.S.C. § 119 to Korean Patent Application No. 10-2021-0144891, filed on Oct. 27, 2021, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.

BACKGROUND

The present disclosure relates to an electronic brake system, and more specifically, to an electronic brake system which stably maintains a parking brake state while a parking brake operates, a vehicle including the same, and a method of operating the same.

2. Description of the Related Art

A brake system for performing braking is necessarily mounted on a vehicle, and the brake system requires a parking brake function for maintaining a stopped state of the vehicle when parked in addition to a service brake function for providing a braking force in a traveling situation of the vehicle.

In conventional parking brakes, a foot brake driven by a foot stepping on a pedal and a hand brake type driven by a hand pulling a lever have been mainly used, but there is a problem in that one hand needs a high force to pull and operate a lever of the parking brake and particularly cause back injuries and a strain on the arm of a driver who frequently parks and stops a vehicle. In addition, since the lever of the parking brake is positioned at the center of a console, the use of an indoor space is limited.

Therefore, recently, a method of implementing electro-mechanical parking brake using an actuator to generate a braking force using a motor by receiving a driver's intention for parking brake as an electric signal in a method of pressing a button has been developed.

An electro-mechanical brake (EMB) system configured to generate a braking force using an electronically controlled motor as a power source may have a simpler configuration than that of a hydraulic brake because it does not generate the braking force using hydraulic pressure and may optimally implement integrated chassis control together with various electronic control devices.

While performing parking brake of the vehicle, a parking unit such as a piston and a nut-spindle of a caliper brake and a parking brake shoe of a drum brake maintains a braking force.

However, even when the parking unit maintains the parking brake force, the parking brake state of the vehicle is released when there is a cause which hinders the maintenance of the parking brake, such as receiving an external impact or having to park the vehicle on a slope, and thus the vehicle may move. Alternatively, when power of the electronic brake system is cut off, since a frictional force between a pad and a disk is lowered, the parking brake state of the vehicle is released and thus the parked vehicle may move.

Therefore, in order to prevent the movement of the vehicle even in the parking brake state, stones or braces are placed between wheels or behind the wheels, but this problem has not been directly solved in the conventional parking brakes, and thus the necessity of solving this has been required.

RELATED ART DOCUMENT

Patent Document

SUMMARY

An embodiment of the present disclosure is directed to providing an electronic brake system which may generate a braking force by a rotation limit unit that limits the rotation of a spindle and a vehicle including the same.

An embodiment of the present disclosure is also directed to providing an electronic brake system which may distribute a rotational force of a spindle applied to a rotation limit unit to a caliper housing through a supporter provided in the caliper housing so that the rotational force of the spindle is prevented from being concentrated to a drive unit and a vehicle including the same.

An embodiment of the present disclosure is also directed to providing an electronic brake system which may generate a braking force by providing an actuator configured to transmit power to a spindle and a separate drive unit and bringing a rotation limit unit into close contact with the spindle and a vehicle including the same.

An embodiment of the present disclosure is also directed to providing an electronic brake system which may decrease current consumption and improve braking reliability and a vehicle including the same.

According to one aspect of an embodiment of the present disclosure, there is provided an electronic brake system including a piston provided in a caliper housing to press a pad plate, a nut configured to move the piston forward or backward, a spindle configured to move the nut forward or backward by rotation and including a stepped portion formed on an outer surface thereof, a rotation limit unit connected to or disconnected from the spindle to allow or block the rotation of the spindle, and a drive unit configured to move the rotation limit unit to a position at which the rotation of the spindle is allowed or blocked, wherein the rotation limit unit includes a body surrounding an outer circumferential surface of the spindle and a binder provided on the body to come into close contact with or be separated from the stepped portion.

Any one of the stepped portion and the binder may include at least one first protrusion, and the other of the stepped portion and the binder may include a first groove connected to the first protrusion.

The first groove may be formed to be recessed in an axial direction of the spindle.

The caliper housing may include a supporter surrounding an outer circumferential surface of the body.

The supporter may include a second groove formed to be recessed in an axial direction of the spindle, and the body may include a second protrusion formed to protrude from a position corresponding to the second groove.

According to another aspect of the embodiment of the present disclosure, there is provided an electronic brake system including a piston provided in a caliper housing to press a pad plate, a nut configured to move the piston forward or backward, a spindle configured to move the nut forward or backward by rotation and including a first groove formed to be recessed in an outer surface thereof, a rotation limit unit including a first protrusion formed to protrude from a position corresponding to the first groove to allow or block the rotation of the spindle and fixedly inserted into the first groove, and a drive unit configured to move the rotation limit unit forward or backward to a position at which the rotation of the spindle is allowed or blocked.

The spindle may include a stepped portion including the first groove and provided on an outer surface of the spindle, and the rotation limit unit may include a body surrounding an outer circumferential surface of the spindle and a binder including the first protrusion and provided on the body to come into close contact with or be separated from the stepped portion.

The first groove may be formed to be recessed in an axial direction of the spindle.

The drive unit may include a motor configured to generate power and a reduction gear connected to a rotational shaft of the motor to transmit a driving force to the rotation limit unit.

The rotation limit unit may further include a connector provided on the body and configured to receive the driving force from the drive unit.

The reduction gear may include a worm connected to the rotational shaft of the motor and a worm gear having an outer side connected to the worm and an inner side connected to the connector.

The connector may be connected to the worm gear to receive the driving force of the motor and may rotate about the axial direction of the spindle.

The connector may have a first screw thread formed on an outer circumferential surface thereof, and the worm gear may have a second screw thread engaged with the first screw thread formed at a position corresponding to the first screw thread.

The caliper housing may include an elastic member configured to elastically support the worm gear.

The nut may have a hollow in a longitudinal direction and a first screw thread, which is screw-coupled to a second screw thread formed on the spindle in a certain section in a longitudinal direction, formed on an inner circumferential surface of the hollow.

The spindle may include a spindle body, a spindle flange formed to extend radially from the spindle body and formed with the stepped portion, and a spindle rod having the second screw thread formed on an outer circumferential surface thereof.

The stepped portion may be formed to extend radially from the outer circumferential surface of the spindle.

The body may surround the spindle body connected to an actuator after passing through a cylinder provided in the caliper housing.

According to still another aspect of the embodiment of the present disclosure, there is provided a vehicle including the electronic brake system.

According to yet another aspect of the embodiment of the present disclosure, there is provided a method of operating an electronic brake system, which includes, in a parking mode, transmitting, by an actuator, a driving force to a spindle so that a nut presses a piston, transmitting, by a drive unit, the driving force to a rotation limit unit and bringing a binder into close contact with a stepped portion, and upon releasing the parking mode, separating the binder from the stepped portion and releasing a state in which the nut presses the piston.

In the bringing of the binder into close contact with the stepped portion, a first protrusion formed on a body may be inserted into a first groove formed in the binder, and in the separating of the binder from the stepped portion, the first protrusion may be released from the first groove.

In the bringing of the binder into close contact with the stepped portion, a second protrusion formed on a body may be inserted into a second groove formed in a supporter to prevent rotation of the body, and in the separating of the binder from the stepped portion, the second protrusion may be released from the second groove.

DETAILED DESCRIPTION

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The following embodiment is presented to sufficiently convey the spirit of the present disclosure to those skilled in the art to which the present disclosure pertains. The present disclosure is not limited to only the embodiment presented herein and may also be specified in other forms. Portions irrelevant to the description will be omitted from the drawings in order to clarify the present disclosure, and the sizes of the components may be described to be slightly exaggerated to help understanding.

FIG.1is a plan view showing an electronic brake system according to one embodiment of the present disclosure,FIG.2is an enlarged view showing a state in which a spindle and a rotation limit unit of the electronic brake system according to one embodiment of the present disclosure come into close contact with each other,FIG.3is an enlarged view showing a state in which the spindle and the rotation limit unit of the electronic brake system according to one embodiment of the present disclosure are separated from each other,FIG.4is a cross-sectional view along line I-I′ inFIG.1viewed in a direction A, andFIG.5is a cross-sectional view along line I-I′ inFIG.1viewed in a direction B.

Referring toFIGS.1to5, the electronic brake system according to one embodiment of the present disclosure may include a piston110provided in a caliper housing100to press a pad plate10, a nut201coupled to the inside of the piston110to move the piston110forward or backward, a spindle200configured to move the nut201forward or backward by rotation and including a stepped portion210formed on an outer surface thereof, a rotation limit unit300connected to or disconnected from the spindle200to allow or block the rotation of the spindle200, and a drive unit400configured to move the rotation limit unit300to a position at which the rotation of the spindle200is allowed or blocked.

A pair of pad plates10includes an inner pad plate arranged to come into contact with the piston110and an outer pad plate arranged to come into contact with a finger portion102of the caliper housing100. The pair of pad plates10may be installed on a carrier50fixed to a vehicle body to move forward to or backward from both side surfaces of a disk D. A friction pad11may be provided to be attached to one surface of each pad plate10facing the disk D.

The caliper housing100is slidably installed on the carrier50. The caliper housing100may include a cylinder101in which the piston110is accommodated to move forward or backward. A power conversion unit may be installed behind the cylinder101(right side based onFIG.1), and the finger portion102formed to be bent forward (left side based onFIG.1) to operate the outer pad plate may be provided. The cylinder101and the finger portion102may be integrally formed.

The caliper housing100may include a supporter120surrounding an outer circumferential surface of a body310of the rotation limit unit300. The supporter120may include a second groove121recessed in a longitudinal direction along an inner circumferential surface thereof. In addition, the caliper housing100may include an elastic member130configured to elastically support a worm gear422.

The piston110may be formed in a hollow shape with an empty inside and provided to be slid in the cylinder101. Specifically, the piston110may be provided in the shape of a hollow cup to come into contact with the nut201. The movement of the piston110may be converted into a translational motion by the power conversion unit receiving power from an actuator40so that the piston110moves forward or backward, and therefore, the piston110may press the inner pad plate toward the disk D to implement braking. In addition, when the piston110moves toward the inner pad plate and presses the inner pad plate, the caliper housing100operates in a direction opposite to the piston110by a reaction force thereof, and therefore, the finger portion102may press the outer pad plate toward the disk D to implement braking.

The power conversion unit is provided to receive power from the actuator40including a motor and a reducer to convert a rotational motion into the translational motion and press the piston110toward the inner pad plate. The power conversion unit includes the nut201disposed inside the piston110and coming into contact with an inner rear surface of the piston110and the spindle200screw-coupled with the nut201.

The nut201is provided to be screw-coupled with the spindle200to move forward or backward and come into contact with the piston110to limit rotation. The nut201functions to move forward or backward according to a rotational direction of the spindle200and press or release the piston110. The nut201has a hollow hollowed in the longitudinal direction, and a first screw portion201ascrew-coupled with a second screw portion204aof the spindle200in a certain section in the longitudinal direction is provided on an inner circumferential surface of the hollow.

The spindle200has one side that is formed with the second screw portion204aand screw-coupled with the first screw portion201aof the nut201, and the other side that is connected to the actuator40and receives the rotational force of the motor in the actuator40. The spindle200may be rotated by receiving the rotational force of the motor and may move the nut201forward or backward through the second screw portion204ascrew-coupled with the first screw portion201a. According to the rotational direction of the spindle200by the motor, the nut201may move forward or backward and press or release the piston110.

Specifically, the spindle200may include a spindle body202, a spindle flange203formed to extend from the spindle body202in a radial direction, and a spindle rod204having the second screw portion204aformed on an outer circumferential surface thereof. The spindle body202may be connected to the actuator40after passing through the cylinder101of the caliper housing100to receive the rotational force of the motor, and the spindle flange203and the spindle rod204may be disposed inside the piston110. By providing a bearing220between the spindle flange203and the cylinder101, the spindle200may be stably rotatably supported in the cylinder101.

The stepped portion210may be formed on the outer surface of the spindle200and formed to extend radially from the outer surface of the spindle200. The stepped portion210may be formed at a position corresponding to a binder320of the rotation limit unit300. The rotation of the spindle200may be limited by bringing the binder320of the rotation limit unit300into close contact with the stepped portion210. A braking state of the vehicle is a state in which the nut201is pressing the piston110, and can prevent the release of the pressing state of the piston110by the nut201by bringing the binder320into contact with the stepped portion210to limit the rotation of the spindle200. Therefore, it is possible to improve braking reliability. The stepped portion210may be formed to extend radially from the outer circumferential surface of the spindle200and specifically may be provided to extend radially from the outer circumferential surface of the spindle body202.

The stepped portion210may include a first protrusion211formed to protrude. The first protrusion211may be formed on a surface facing the binder320. The first protrusion211may be inserted into a first groove321formed in the binder320, and in the inserted state, the first protrusion211may be caught by both side ends of the first groove321to limit the rotation of the spindle200. The positions of the first protrusion and the first groove are not limited thereto, and conversely, the first groove may be formed in the stepped portion210, and the first protrusion may be formed on the binder320. In other words, any one of the stepped portion210and the binder320may include at least one first protrusion, and the other may include the first groove connected to the first protrusion. The first protrusion may be formed to protrude in an axial direction of the spindle, and the first groove may be formed to be recessed in the axial direction of the spindle200.

The first protrusion211and the first groove321may be provided in a ratchet shape and provided to allow unidirectional rotation of the spindle200and limit the rotation in a direction opposite to the unidirectional rotation when the first protrusion211is inserted into the first groove321. When the rotation limit unit300and the spindle200are connected, only the unidirectional rotation of the spindle200may be allowed to prevent the movement of the nut201without being fixed due to the rotation of the spindle200in the opposite direction. Therefore, it is possible to improve the reliability of the restraint for the spindle200of the rotation limit unit300.

For example, in the state in which the rotation limit unit300comes into close contact with the spindle200and the first protrusion211is inserted into the rotation limit unit300, the spindle200may not rotate in the opposite direction, and thus it is possible to maintain the state in which the nut201presses the piston110. Conversely, when the rotation limit unit300is separated from the spindle200and the first protrusion211comes out of the first groove321, the spindle200may rotate in the opposite direction, and thus it is possible to release the state in which the nut201presses the piston110.

The rotation limit unit300may be connected to the spindle200to limit the rotation of the spindle200. The rotation limit unit300may be provided behind the power conversion unit. The rotation limit unit300may include a body310surrounding the outer circumferential surface of the spindle200, the binder320provided on one side of the body310to come into close contact with the stepped portion210of the spindle200, and a connector330that is provided on the other side of the body310and interlocks with the drive unit400.

The body310is provided between the caliper housing100and the spindle200and provided to surround the outer circumferential surface of the spindle200. The body310in the caliper housing100may be provided to surround the outer circumferential surface of the spindle200and thus a separate space for the rotation limit unit300does not have to be provided. Therefore, it is possible to improve space utilization in the caliper housing100. Specifically, the body310may surround the spindle body202connected to the actuator40after passing through the cylinder101of the caliper housing100.

Since the body310may move forward or backward in the supporter120surrounding the rotation limit unit300, the body310may not deviate from a path of the rotation limit unit300in the supporter120and may come into close contact with or be separated from the spindle200.

The body310may include a second protrusion311formed to protrude along the outer circumferential surface at the position corresponding to the second groove121formed to be recessed along the inner circumferential surface of the supporter120. When the body310of the rotation limit unit300moves into the supporter120, the second protrusion311is inserted into the second groove121. When the second protrusion311is inserted into the second groove121and the body310is to be rotated, the second protrusion311may be caught by both side ends of the second groove121, thereby preventing the body310from being rotated. Therefore, when the binder320comes into close contact with the stepped portion210and the first protrusion211is inserted into the first groove321, the body310, the binder320, and the stepped portion210can be prevented from being rotated together, and thus it is possible to fix the position of the nut201by preventing the rotation of the spindle200. Therefore, it is possible to improve braking reliability.

In addition, when the spindle200is restricted by the rotation limit unit300, the rotational force of the spindle200is transmitted to the supporter120through the second protrusion311and the second groove121, and the caliper housing100supports the rotational force. Since it is possible to prevent the rotational force of the spindle200from being concentrated to the drive unit400, it is not necessary to design the caliper housing100on the side where the drive unit400is installed to have high stiffness, and it is possible to increase the durability of the drive unit400. Therefore, design and cost advantages can be obtained.

The binder320is provided on the body310and comes into close contact with the stepped portion210of the spindle200. The binder320may come into close contact with the stepped portion210to limit the rotation of the spindle200. In order to improve the reliability of the restraint for the spindle200of the rotation limit unit300, the binder320may include the first groove321formed to be recessed in the outer surface thereof, and the first groove321may be formed in the surface facing the stepped portion210. The first protrusion211formed on the stepped portion210may be inserted into the first groove321, and the rotation of the spindle200may be limited in the inserted and connected state. Conversely, the first groove321may be formed in the stepped portion210and the first protrusion211may be formed on the binder320so that a connecting structure may also be provided. It is possible to improve the reliability of the restraint for the spindle200of the rotation limit unit300by providing the first protrusion211and the first groove321in the ratchet shape. The first protrusion211may be formed to protrude in the axial direction of the spindle200, and the first groove321may be formed to be recessed in the axial direction of the spindle200.

The connector330may be provided on the body310and may receive a driving force from the drive unit400. Specifically, the connector330may be interlocked with the worm gear422of the motor to receive the driving force of the motor and may rotate around the axial direction of the spindle200. The connector330may rotate and the rotation limit unit300may move in the axial direction of the spindle200. Therefore, the binder320may come into close contact with or be separated from the stepped portion210.

The connector330may have a first screw thread331provided on an outer circumferential surface thereof. The first screw thread331may be engaged with a second screw thread422bprovided on an inner circumferential surface of the worm gear422, and the driving force transmitted from the motor410to the worm gear422through a worm421may be transmitted to the connector330. In addition, the first screw thread331of the connector330and the second screw thread422bof the worm gear422may be engaged with each other, and thus a self-locking structure in which the positions of the worm421and the connector330are fixed even when the driving force of the motor is not transmitted from the worm421to the worm gear422may be formed. Therefore, it is possible to improve a restricting force of the rotation limit unit300with respect to the spindle200by supporting the rotation limit unit300with a large force.

The drive unit400may include the motor410configured to generate power and a reduction gear420connected to a rotational shaft411of the motor410to transmit the driving force to the rotation limit unit300.

The motor410may receive power by operating a switch provided on the driver seat of the vehicle and convert electrical energy into mechanical rotational kinetic energy. The control of the parking mode according to an operation signal of the switch may be performed by an electronic control unit (ECU) of the vehicle.

The reduction gear420may include the worm421connected to the rotational shaft411of the motor410and the worm gear422having an outer side connected to the worm421and an inner side connected to the connector330of the rotation limit unit300. The driving force of the motor410may be transmitted to the rotation limit unit300through the reduction gear420to limit the rotation of the spindle200.

The worm421rotates about the rotational shaft411of the motor410. The worm gear422interlocked with the worm421rotates while changing a rotation direction thereof to a direction perpendicular to the rotational shaft411of the motor410. At this time, a gear teeth421aformed on the worm421and a gear teeth442aformed on the worm gear422are engaged with each other, and the driving force of the motor410is transmitted to the worm gear422through the worm421. The worm gear422transmits the driving force of the motor410to the connector330through the second screw thread422bengaged with the first screw thread331formed on an outer circumferential surface of the connector330. At this time, the worm gear422and the connector330may be provided with the self-locking structure.

The worm gear422may be elastically supported by the elastic member130provided in the caliper housing100. The driving force may be transmitted to the connector330through the worm gear422, and when the rotation limit unit300comes into close contact with or is separated from the spindle200, a reaction force may be applied to the worm gear422. At this time, the elastic member130may elastically support the worm gear422in a direction opposite to the reaction force applied to the worm gear422. Therefore, it is possible to constantly maintain the position of the worm gear422in the caliper housing100, and it is possible to uniformly maintain the fixed position when the rotation limit unit300moves forward or backward. Therefore, it is possible to uniformly maintain the positions and movement distance where the rotation limit unit300moves forward or backward, and it is possible to improve the reliability of the restraint of the rotation limit unit300with respect to the spindle200.

In addition, the electronic brake system may be mounted on the vehicle to implement the parking brake force and secure the braking reliability.

Hereinafter, a method of operating the electronic brake system according to one embodiment of the present disclosure will be described. The electronic brake system according to one embodiment of the present disclosure may operate in a parking mode for maintaining the parking brake state of the vehicle and may be operated to release the parking mode due to the release of the parking brake of the vehicle.

First, when a driver operates a parking switch or the like for parking brake of the vehicle, the actuator40operates to transmit a driving force to the spindle200. When the spindle200rotates, the nut201moves in the axial direction, and the nut201presses the piston110and thus braking is performed.

The rotation limit unit300is provided to come into close contact with or be separated from the spindle200by receiving the driving force from the drive unit400provided separately from the actuator40. The drive unit400receives an electrical signal from the ECU or the like to generate power by the motor410and moves the rotation limit unit300through the reduction gear420.

In the parking mode, the drive unit400receives the electrical signal from the ECU or the like and generates the driving force by the motor410. The rotation limit unit300receives the driving force through the connector330interlocked with the reduction gear420and comes into close contact with the spindle200. The binder320may come into close contact with the stepped portion210, and the first protrusion211formed on the stepped portion210may be inserted into the first groove321formed in the binder320to limit the spindle200, thereby preventing the parking brake of the vehicle from being released. At this time, the second protrusion311formed on the body310may be inserted into the second groove121to prevent the rotation limit unit300from rotating together with the spindle200, thereby preventing the parking brake of the vehicle from being released.

When the parking mode is released, the rotation limit unit300receives the driving force through the connector330interlocked with the reduction gear420and is separated from the spindle200. At this time, the rotational shaft411of the motor410rotates in a direction opposite to that in the parking mode. The binder320is separated from the stepped portion210so that the first protrusion211comes out of the first groove321. The connected state between the rotation limit unit300and the spindle200is released, and thus the spindle200may rotate again. After the parking mode is released, the spindle200receiving the driving force from the actuator40rotates and moves the nut201rearward to release the state in which the nut201presses the piston110, and thus it is possible to release the parking brake state of the vehicle. At this time, the second protrusion311formed on the body310may be released from the second groove121.

As described above, the electronic brake system according to one embodiment of the present disclosure may limit the rotation of the spindle200through the rotation limit unit300, thereby preventing the braking from being released in the parking brake state. At this time, the spindle200is restricted by the rotation limit unit300, and the rotational force of the spindle200may be distributed to the caliper housing100through the supporter120, thereby preventing the rotational force of the spindle200from being concentrated to the drive unit400. In addition, since the separate drive unit400may be provided to bring the rotation limit unit300into close contact with the spindle200or separate the rotation limit unit300from the spindle200, it is possible to decrease the current consumption without continuously applying the current in the parking mode and bring the rotation limit unit300into contact with the spindle200with a strong axial force in the parking mode.

An electronic brake system and a vehicle including the same according to one embodiment of the present disclosure can generate a braking force by a rotation limit unit that limits the rotation of a spindle.

An electronic brake system and a vehicle including the same according to one embodiment of the present disclosure can distribute a rotational force of a spindle applied to a rotation limit unit through a supporter to a caliper housing, thereby preventing the rotational force of the spindle from being concentrated to the drive unit.

An electronic brake system and a vehicle including the same according to one embodiment of the present disclosure can generate a braking force by providing an actuator configured to transmit power to a spindle and a separate drive unit and bringing a rotation limit unit into close contact with the spindle.

An electronic brake system and a vehicle including the same according to one embodiment of the present disclosure can decrease current consumption and improve braking reliability.

As described above, although the present disclosure has been described with reference to limited embodiments and drawings, it goes without saying that the present disclosure is not limited thereto, and various modifications and variations are possible by those skilled in the art to which the present disclosure pertain within the technical spirit of the present disclosure and an equivalent scope of the claims to be described below.