Electric brake system and operating method thereof

Abstract

An electric brake system and an operating method thereof are disclosed. This embodiment can provide an electric brake system and an operating method thereof, wherein the electric brake system includes: a pair of backing plates disposed on either side of a disc that rotates with a wheel; a piston configured to bring the backing plates into close contact with or separate from the disc; a first motor and a second motor configured to operate independently of each other and provide power to the piston; a first gear configured to reduce the power of the first motor and transmit the reduced power; a second gear configured to convert the power of the second motor into translational motion and apply pressure to or release pressure on the piston when in contact with the piston, the second gear including a guide portion obliquely formed on a portion that contacts the piston; and a connecting portion connecting the first gear and the second gear to each other so that the first gear and the second gear rotate together, the connecting portion configured to couple the first gear and the second gear so that the second gear can slide relative to the first gear.

Description

Technical Field

[0001] The present disclosure relates to an electro-mechanical brake system and an operating method thereof, and more particularly, to an electro-mechanical brake system and an operating method thereof for achieving vehicle braking and parking using motor power. Background Art

[0002] The electric brake system of the new generation braking concept refers to a device for detecting the driver's braking intention and then adjusting the brake pressure of the front and rear wheels using an electric motor such as a motor.

[0003] The electric braking system can realize various types of intelligent functions, including general braking functions, anti-lock braking system (ABS) functions, electronic stability control (ESC) functions, vehicle dynamic control (VDC) functions, as well as automatic braking functions required by future intelligent constant speed driving devices.

[0004] This electric brake system uses a motor and a retarder to generate appropriate brake pressure in the caliper, and performs service brake and parking brake functions through the brake pressure. Summary of the Invention

[0005] Therefore, an object of the present disclosure is to provide an electric brake system and an operating method thereof that can effectively implement braking under various operating conditions.

[0006] An object of the present disclosure is to provide an electric brake system capable of achieving rapid braking and an operating method thereof.

[0007] An object of the present disclosure is to provide an electric brake system and an operating method thereof having improved performance and operational reliability.

[0008] An object of the present disclosure is to provide an electric brake system having improved product durability by reducing loads applied to constituent elements, and an operating method thereof.

[0009] The technical purpose of the present disclosure is not limited to the above contents, and other purposes may be apparent to those skilled in the art based on the following description.

[0010] According to one aspect of the present disclosure, an electric brake system is provided, which includes: a pair of pads arranged on both sides of a disc that rotates with a wheel; a piston configured to make the pads in close contact with or separate from the disc; a first motor and a second motor configured to operate independently of each other and provide power to the piston; a first gear configured to reduce the power of the first motor and transmit the reduced power; a second gear configured to convert the power of the second motor into a translational motion and apply pressure to or release pressure on the piston while in contact with the piston, the second gear including a guide portion obliquely formed on a portion of the second gear that contacts the piston; and a connecting portion that connects the first gear and the second gear to each other so that the first gear and the second gear rotate together, the connecting portion configured to couple the first gear and the second gear so that the second gear can slide relative to the first gear.

[0011] The connection portion may include: a plurality of connection holes passing through the upper and lower sides of the first gear; and a plurality of connection pins disposed to be slidably coupled to the plurality of connection holes.

[0012] The guide portion may include: a first surface protruding forward and having a slope so that the force pressing the piston gradually increases during rotation of the second gear; and a second surface obliquely recessed backward so that the force pressing the piston by the first surface is released.

[0013] The electric brake system may further include a belt portion configured to transmit power output through the drive shaft of the first motor to the first gear.

[0014] The second gear may be provided with a nut portion which enables the second gear to move forward and backward according to rotation of a main shaft for outputting power of the second motor.

[0015] A plurality of guide portions may be continuously provided on the front surface of the second gear in a circumferential direction.

[0016] The guide portion may be arranged to be in contact with the rear portion of the piston.

[0017] The piston may include a rotating ball supported at a rear end of the piston to achieve free rotation.

[0018] The nut part may be formed in a hollow cylindrical shape and connected with the second motor through the first gear.

[0019] The electric brake system may further include: a control portion configured to detect whether the first motor and the second motor are operated, and control the operation of the first motor and the second motor.

[0020] According to another aspect of the present disclosure, an operating method of an electric brake system is provided, wherein the guide portion is provided as a plurality of guide portions continuously arranged along the circumferential direction of the second gear, and the first gear and the second gear rotate together according to the operation of the first motor, repeatedly applying pressure to and releasing the pressure on the piston.

[0021] The second gear may be configured to slidably advance to press the piston when the second motor rotates in one direction, and slidably retreat to release pressure on the piston when the second motor rotates in an opposite direction.

[0022] In a first mode in which an anti-lock braking system (ABS) is implemented, the control portion may be configured to control the first motor to be driven while preventing the second motor from being driven.

[0023] In the second mode of stopping the vehicle, the controller may be configured to control the second motor to rotate in one direction.

[0024] In the third mode for implementing emergency braking, the control portion may be configured to control the first motor to drive in a direction in which the guide portion presses the piston, and control the second motor to rotate in the one direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] These and / or other aspects of the present disclosure will become more apparent and easier to understand from the following description of the embodiments in conjunction with the accompanying drawings, which are as follows:

[0026] Figure 1 is a view showing a caliper brake to which an electric brake system according to an embodiment of the present disclosure is applied;

[0027] Figure 2 is a view showing an electric brake system according to an embodiment of the present disclosure;

[0028] Figure 3 is an exploded perspective view showing an electric brake system according to an embodiment of the present disclosure;

[0029] Figure 4 is a combined perspective view showing an electric brake system according to an embodiment of the present disclosure;

[0030] Figure 5 is a perspective view showing a guide portion viewed from below according to an embodiment of the present disclosure; and

[0031] Figures 6 and 7 is a graph illustrating brake force according to the operation of the electric brake system of the present disclosure. DETAILED DESCRIPTION

[0032] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The following embodiments are presented to fully convey the spirit of the present disclosure to those skilled in the art. The present disclosure is not limited to the embodiments presented herein and may be implemented in other forms. The drawings may omit portions not relevant to the description to clarify the present disclosure, and may slightly exaggerate the dimensions of components to aid understanding.

[0033] Reference Figures 1 to 5 The electric brake system according to the present disclosure includes: a pair of backing plates 21 and 22 provided on both sides of a disk D that rotates together with a wheel; a piston 100 configured to bring the backing plates 21 and 22 into close contact with or separate from the disk D; a first motor M1 and a second motor M2 configured to operate independently of each other and provide power to the piston 100; a first gear 210 configured to reduce the power of the first motor M1 and transmit the reduced power; a second gear 220 configured to convert the power of the second motor M2 into translational motion and apply pressure to or release pressure on the piston 100 when in contact with the piston 100, the second gear 220 including a plurality of guide portions obliquely formed on a portion of the second gear that contacts the piston 100; and a connecting portion 230 connecting the first gear 210 and the second gear 220 to each other so that the first gear 210 and the second gear 220 rotate together, the connecting portion 230 configured to mesh the first gear 210 and the second gear 220 so that the second gear 220 can slide relative to the first gear.

[0034] The electric brake system according to the present embodiment may be applied to, for example, a floating type caliper brake, but the present disclosure is not limited thereto.

[0035] Reference Figure 1 , a pair of backing plates 21 and 22 can be slidably mounted on a carrier (not shown) of the caliper housing 10, and friction pads 23 and 24 can be attached to the inner surface of each of the pair of backing plates 21 and 22. The pair of backing plates 21 and 22 can include an inner backing plate 21 and an outer backing plate 22, the outer surface of the inner backing plate 21 is pressed or released by the piston 100, and the outer surface of the outer backing plate 22 is provided to contact the finger-shaped portion 12 of the caliper housing 10, so that the pair of backing plates 21 and 22 can be slidably mounted on the carrier.

[0036] The caliper housing 10 includes a finger 12 for operating the outer pad 22 and a cylinder 11 on which a piston 100 is mounted, and is slidably coupled to the carrier. Therefore, during a braking operation, the caliper housing 10 is moved by a repulsive force generated according to the movement of the piston 100. Figure 1 The outer pad 22 is slidably moved rightward from the carrier so that the outer pad 22 is pushed toward the disk D by the finger-shaped member 12 and pressed against the disk D.

[0037] The piston 100 can apply or release pressure on the outer surface of the inner shim plate 21. The piston 100 can press the inner shim plate 21 against or separate it from the disc D using the power transmission unit 200, which will be described below. Specifically, the piston 100 can apply pressure to the inner shim plate 21, bringing it into close contact with the disc D, or release pressure on the inner shim plate 21, separating it from the disc D. In other words, the piston 100 advances and retracts within the cylinder 11 of the caliper housing 10 to apply or release pressure on the inner shim plate 21. Meanwhile, the unexplained reference numeral "101" denotes a rotating ball 101 inserted into the rear end of the piston 100 and supported for free rotation. The rotating ball 101 allows the first surface 221a and second surface 221b of the guide portion 221, which will be described below, to smoothly pass over the piston 100.

[0038] On the other hand, the unexplained reference numeral “120” denotes a cup-shaped portion 120 housed in the cylinder 11 of the caliper housing 10. The cup-shaped portion 120 may have one side opening to house the piston 100 and may be slidably inserted into the cylinder of the caliper housing 10. The cup-shaped portion 120 may apply pressure to the inner gasket 21 or release pressure on the inner gasket 21 by the axial force of the piston 100.

[0039] The piston 100 may have a front end facing the inner shim plate 21 and a rear end drivingly connected to the power transmission unit 200, as described below. The power of the first motor M1 or the second motor M2 may be transmitted to the piston 100 via the power transmission unit 200, and the axial force of the piston 100 may apply pressure to the inner shim plate 21 or release the pressure on the inner shim plate 21.

[0040] The first motor M1 and the second motor M2 can operate independently of each other. The first motor M1 and the second motor M2 are configured to receive electricity from a power supply device (not shown) such as a vehicle battery to generate and provide the power required to brake and release the vehicle. The first motor M1 and the second motor M2 may respectively include a drive shaft that transmits power to the outside. In addition, the first motor M1 can be configured as a direct current (DC) motor or an alternating current (AC) motor, and the same applies to the second motor M2. On the other hand, the operations of the first motor M1 and the second motor M2 can be controlled independently of each other, and the power according to the rotation of the first motor M1 and the second motor M2 can be provided through the power transmission part 200 as the power for the forward and backward movement of the piston 100.

[0041] The power transmission part 200 is provided to transmit the power of the first motor M1 and the second motor M2 to the piston 100. In more detail, the power transmission part 200 may include a first gear 210, a second gear 220, and a connection part 230.

[0042] Reference Figures 2 to 5 , the first gear 210 can be drivingly connected to the drive shaft of the first motor M1. The first gear 210 can reduce the power generated according to the rotation of the first motor M1 and transmit the power to the second gear 220. The first gear 210 can be connected to the drive shaft of the first motor M1 through the belt portion 240. The belt portion 240 transmits the power output through the drive shaft of the first motor M1 to the first gear 210. A thread 210a may be formed on the outer circumferential surface of the first gear 210, and a thread corresponding to the thread 210a of the first gear 210 may be formed on the inner circumferential surface of the belt portion 240 to engage with the thread 210a. On the other hand, the first gear 210 can be set to a spur gear shape, but the present disclosure is not limited thereto.

[0043] The second gear 220 can convert the power of the second motor M2 into translational motion. That is, when the second motor M2 rotates in one direction, the second gear 220 can slide in the direction of pressing the piston 100, and when the second motor M2 rotates in the opposite direction, the second gear 220 can slide in the direction of releasing the pressure on the piston 100. Figure 2 When the second motor M2 rotates in one direction, the second gear 220 slides downward to press the piston 100 , and when the second motor M2 rotates in the opposite direction, the second gear 220 slides upward to release the pressure on the piston 100 .

[0044] The second gear 220 may include a body portion 222 , a nut portion 223 having a hollow cylindrical shape and protruding upward from an upper surface of the body portion 222 , and a guide portion 221 protruding downward from a lower surface of the body portion 222 and having an inclined shape.

[0045] As shown in the figure, the main body 222 of the second gear 220 can be set to a disc shape with a predetermined thickness, but is not limited thereto and can be set to various shapes. A nut portion 223 can be provided on the upper surface of the main body 222 of the second gear 220. As shown in the figure, the nut portion 223 of the second gear 220 can be set to a hollow cylindrical shape. The nut portion 223 of the second gear 220 can be inserted through the through portion 212 on the upper and lower sides of the first gear 210. On the other hand, the nut portion 223 of the second gear 220 can be connected to the main shaft S for outputting the power of the second motor M2, as described below, and moves forward and backward according to the rotation of the main shaft S.

[0046] Reference Figures 4 and 5The guide portion 221 of the second gear 220 can be formed on the front surface of the second gear 220 so as to contact the rear end of the piston 100. Depending on the operation of the second gear 220, the guide portion 221 of the second gear 220 can apply pressure to the rear end of the piston 100 or release the pressure on the rear end of the piston 100. As shown in the figure, the guide portion 221 can be formed with a slope. On the other hand, multiple guide portions 221 are arranged along the circumference, and when the first motor M1 is driven, the first gear 210 and the second gear 220 rotate together to repeatedly transmit the force that presses the piston 100 or releases the pressure on the piston 100. When pressed by the second gear 220, the piston 100 can advance within the cylinder 11 of the caliper housing 10 to press the inner gasket 21. When released by the second gear 220, the piston 100 can retreat within the cylinder 11 of the caliper housing 10 to release the pressure on the inner gasket 21.

[0047] On the other hand, the guide portion 221 may have a first surface 221a and a second surface 221b. The first surface 221a of the guide portion 221 may protrude forward and have a slope so that the force pressing the piston 100 gradually increases during the rotation of the second gear 220, and the second surface 221 may be recessed backward so that the force pressing the piston 100 by the first surface 221a is released. A plurality of guide portions 221 may be arranged in a circle on the lower surface of the main body 222 of the second gear 220. On the other hand, as shown in the figure, the second surface 221b may be formed to be perpendicular to the main body 222, but is not limited thereto, and may be formed to have a predetermined inclination angle relative to the main body 222. On the other hand, four guide portions 221 may be provided as shown in the figure, but the number of guide portions 221 is not limited thereto, and a different number may be provided according to the design.

[0048] Reference Figure 5 When the second gear 220 rotates clockwise, the force pressing the piston 100 gradually increases in the portion where the first surface 221a of the guide portion 221 passes the rear end of the piston 100, while the force pressing the piston 100 is released in the portion where the second surface 221b of the guide portion 221 passes the rear end of the piston 100. In other words, in the portion where the first surface 221a of the guide portion 221 passes the rear end of the piston 100, the second gear 220 slides in the direction in which the piston 100 presses the inner gasket 21, while in the portion where the second surface 221b of the guide portion 221 passes the rear end of the piston 100, the second gear 220 slides in the direction in which the piston 100 releases the pressure on the inner gasket 21.

[0049] The connecting portion 230 may connect the first gear 210 and the second gear 220 to each other so that the first gear 210 and the second gear 220 rotate together, so that the second gear 220 is slidably coupled to the first gear 210. More specifically, the connecting portion 230 may include a plurality of connecting holes 231 passing through an upper side of the first gear 210 and a lower side of the first gear 210, and a plurality of connecting pins 232 protruding from the main body 222 and slidably coupled to the plurality of connecting holes 231.

[0050] The connecting portion 230 may be configured to guide the second gear 220 to rotate together with the first gear 210 by rotating the first gear 210 when the first motor M1 rotates. That is, since the connecting pin 232 of the second gear 220 is inserted into the connecting hole 231 of the first gear 210, the rotational force of the first gear 210 is transmitted to the second gear 220 through the connecting hole 231 and the connecting pin 232, so that the second gear 220 rotates together with the first gear 220.

[0051] In addition, the connecting portion 230 can be configured to guide the second gear 220 to slide forward or backward relative to the first gear 210 by the second motor M2 rotating in one direction or the opposite direction. When the main shaft S that outputs the power of the second motor M2 rotates in one direction or the opposite direction, the nut portion 223 of the second gear 220 connected to the main shaft S is set to slide forward or backward without rotating together with the main shaft S. That is, with the connecting pin 232 inserted into the connecting hole 231 of the first gear 210, the second gear 220 is prevented from rotating together with the main shaft S. Therefore, the rotational force of the main shaft S for outputting the power of the second motor M2 is converted into a translational motion, and the second gear 220 can slide forward and backward relative to the first gear 210. Figure 2 , the second gear 220 can slide downward to press the piston 100 or slide upward to release the pressure on the piston 100.

[0052] The second gear 220 may include a nut portion 223 that is reciprocally coupled to the main shaft S. As shown in the figure, the main shaft S may be configured to be indirectly connected to the second motor M2 via a reduction gear portion G. Alternatively, the main shaft S may be configured as a drive shaft for the second motor M2, i.e., a direct connection may be employed. On the other hand, the reduction gear portion G may be configured as various types of gears and may reduce the power of the second motor M2 and transmit the power to the main shaft S.

[0053] On the other hand, the second gear 220 can slide forward to press the piston 100 when the second motor M2 rotates in one direction, and slide backward to release the pressure of the piston 100 when the second motor M2 rotates in the opposite direction. On the other hand, the guide portion 221 is provided in plurality, and when the first motor M1 is driven, the first gear 210 and the second gear 220 can rotate together to repeatedly transmit the force of pressing the piston 100 or releasing the piston 100.

[0054] That is, the second gear 220 can rotate when the first motor M1 is driven so that the first surface 221a and the second surface 221b of each of the plurality of guide portions 221 sequentially press the piston and then release the pressure on the piston 100. In addition, the second gear 220 can slide forward in a direction of pressing the piston 100 when the second motor M2 rotates in one direction, and slide backward in a direction of releasing the pressure on the piston 100 when the second motor M2 rotates in the opposite direction.

[0055] The electric brake system according to the present disclosure may further include a control unit (not shown). The control unit according to an embodiment of the present disclosure may be implemented by a non-volatile memory (not shown) and a processor (not shown), the non-volatile memory being configured to store data related to an algorithm for controlling the operation of various components or software instructions for reproducing the algorithm, and the processor being configured to use the data stored in the memory to perform the following operations. Here, the memory and the processor may be implemented as different chips. Alternatively, the memory and the processor may be implemented as a single chip integrated with each other. The processor may take the form of one or more processors.

[0056] The control portion may detect whether the first motor M1 and the second motor M2 are operated and control the operations of the first motor M1 and the second motor M2 .

[0057] Hereinafter, the operation of the electric brake system according to the present disclosure will be described.

[0058] The first mode is to implement the anti-lock braking system (ABS) when braking is performed while the vehicle is traveling. In the first mode, the control unit controls the first motor M1 to be driven and controls the second motor M2 not to be driven. When the first motor M1 is driven, the drive shaft of the first motor M1 rotates, and the belt portion 240 connected to the drive shaft of the first motor M1 transmits the power of the first motor M1 to the first gear 210. The first gear 210 can be driven along the belt portion 240. Figure 3 In addition, the second gear 220 can receive the rotational force of the first gear 210 through the connecting portion 230, thereby rotating in the direction of "T1". Figure 3 On the other hand, the rear end of the piston 100 contacts the guide portion 221 of the second gear 220 .

[0059] In the first mode, the rotation of the second gear 220 causes the rear end of the piston 100 to receive a gradually increasing force while moving along the first surface 221a of the guide portion 221, thereby Figure 3 Then, when the second gear 220 continues to rotate in the direction of "T2", the piston 100 passes the first surface 221a of the guide portion 221 to be located on the second surface 221b of the guide portion 221. Therefore, the pressure on the piston 100 is released, thereby Figure 3 On the other hand, as shown in the figure, since a plurality of guide portions 221 are provided, the force for pressing and releasing the piston 100 according to the rotation of the second gear 220 can be repeatedly applied. Therefore, the piston 100 can repeatedly press and release the inner pad 21. Figure 6 : is a diagram illustrating the braking force of the brake according to the rotation of the second gear. Figure 6 As shown, the horizontal axis represents the rotation angle (degrees) of the second gear 220, and the vertical axis represents the braking force F of the brake acting on the disc. On the other hand, the dotted line marked "C1" in the figure represents the level of braking force that stops the wheels of the vehicle. The electric brake system of the present disclosure can be implemented so that even when the first motor M1 rotates continuously in only one direction, the disc D is repeatedly pressed and released to prevent the locking phenomenon in which the wheels of the vehicle come to a complete stop. Therefore, when the first mode is implemented, the wheels of the vehicle are prevented from coming to a complete stop, and the vehicle is prevented from sliding or moving sideways, thereby improving driving stability.

[0060] Reference Figure 6 , the brake force has a form of increasing and decreasing with an equal rotation angle of 90° of the second gear 220. Figure 6 This diagram illustrates a state where four guides 221 are provided. The duration of the brake force application varies depending on the number of guides 221. Specifically, when three guides 221 are provided, the brake force application period can extend over a rotation angle of 120°. Specifically, the brake force F increases during the period when the first surface 221a of the guide 221 contacts the piston 100, while the brake force decreases during the period when the second surface 221b of the guide 221 passes the piston 100.

[0061] on the other hand, Figure 6 The unexplained reference numeral "C2" represents the initial value of the brake force F. The position of "C2" can be controlled by adjusting the position of the second gear 220 via the second motor M2. In other words, the position of "C2" can be shifted upward or downward on the curve depending on the position of the second gear 220. Conversely, the solid line graph of the brake force F can be shifted upward or downward depending on the position of "C2."

[0062] The second mode is to implement the stopping (or parking) of the vehicle. In the second mode, the control unit can control the second motor M2 to rotate in one direction. When the second motor M2 rotates in one direction, the main shaft S connected to the second motor M2 can rotate in the same direction. Figure 3 The spindle S can transmit the power of the second motor M2 to the nut portion 223 of the second gear 220. The second gear 220 and the nut portion 223 of the second gear 220 are rotated in the positive direction (T3) by the spindle S. Figure 3 The piston 100 is pressed to slide along the "L3" direction in the Figure 3 On the other hand, in order to release the stopped (or parked) vehicle, the control unit may control the second motor M2 to rotate in the opposite direction. In this case, the main shaft S connected to the second motor M2 may be rotated in the opposite direction. Figure 3 Therefore, the second gear 220 slides in the "L4" direction, and the piston 100 is released to slide in the "L2" direction to release the vehicle from stopping (or parking).

[0063] The third mode is for emergency braking. In this mode, the control unit controls the first motor M1 to be driven and the second motor M2 to rotate in one direction. When this mode is in effect, the power of both the first and second motors M1, M2, is transmitted to the second gear 220, thereby maximizing the force exerted on the piston 100. Figure 7 is a graph showing the braking force of the brake according to time when the brake is operated. Figure 7 In FIG, the horizontal axis represents time t and the vertical axis represents the brake force F. On the other hand, Figure 7 “D1” in FIG. 1 represents the braking force F when braking is performed using only the second motor M2 , and “D2” represents the braking force when braking is performed using only the first motor M1 . Figure 7 "D3" in the figure represents the braking force F during emergency braking using the first motor M1 and the second motor M2. In the third emergency braking mode, the first motor M1 and the second motor M2 are used simultaneously to apply the braking force, thereby instantly maximizing the force exerted on the piston 100. This shortens the braking distance of the vehicle.

[0064] On the other hand, when the first motor M1 fails, the control unit can send a warning message to the driver through the instrument panel, etc., and when braking is required during driving, the control unit can rotate the second motor M2 in one direction to apply pressure to the piston, thereby applying the brake.

[0065] As apparent from the foregoing, the electric brake system and method of operating the same can effectively apply braking in a variety of operating situations.

[0066] The electric brake system and the operating method thereof can achieve rapid braking.

[0067] The electric brake system and method of operating the same may have improved performance and operational reliability.

[0068] The electric brake system and the operating method thereof may provide improved product durability by reducing the load applied to component elements.

[0069] Although the embodiments of the present disclosure have been described for illustrative purposes, it will be appreciated by those skilled in the art that various modifications, additions and substitutions may be made without departing from the scope and spirit of the present disclosure. Therefore, the embodiments of the present disclosure are not described for limiting purposes.

Claims

1. An electric brake system comprising: a pair of shims provided on either side of the disc that rotates with the wheel; a piston configured to bring the backing plate into close contact with the disk or to separate the backing plate from the disk; a first motor and a second motor configured to operate independently of each other and to provide power to the piston; a first gear configured to reduce the power of the first motor and transmit the reduced power; a second gear configured to convert power of the second motor into translational motion and apply pressure to or release pressure on the piston when in contact with the piston, the second gear comprising a guide portion obliquely formed on a portion of the second gear in contact with the piston; as well as A connecting portion connects the first gear and the second gear to each other so that the first gear and the second gear rotate together, the connecting portion being configured to couple the first gear and the second gear so that the second gear can axially slide relative to the first gear.

2. The electric brake system according to claim 1, wherein the connecting portion comprises: a plurality of connecting holes passing through the upper side and the lower side of the first gear; and a plurality of connecting pins configured to be slidably coupled to the plurality of connecting holes.

3. The electric brake system according to claim 1, wherein the guide portion comprises: a first surface protruding forward and having a slope so that a force pressing the piston gradually increases during rotation of the second gear; and a second surface that is inclined and recessed rearward so that the force pressing the piston through the first surface is released.

4. The electric brake system according to claim 1, further comprising: The belt portion is configured to transmit power outputted from the driving shaft of the first motor to the first gear. 5 . The electric brake system according to claim 1 , wherein the second gear is provided with a nut portion that allows the second gear to move forward and backward according to rotation of a main shaft for outputting power of the second motor. 6 . The electric brake system according to claim 3 , wherein a plurality of the guide portions are continuously provided on the front surface of the second gear in a circumferential direction. 7 . The electric brake system according to claim 6 , wherein the guide portion is provided to be in contact with a rear portion of the piston. 8 . The electric brake system according to claim 7 , wherein the piston includes a rotating ball supported at a rear end of the piston to be freely rotatable. 9 . The electric brake system according to claim 5 , wherein the nut portion is formed in a hollow cylindrical shape and is connected to the second motor through the first gear.

10. The electric brake system according to claim 1, further comprising: The control unit is configured to detect whether the first motor and the second motor are operating and control the operation of the first motor and the second motor.

11. A method for operating an electric brake system, the method being the method for operating an electric brake system according to claim 10, wherein the guide portion is provided as a plurality of guide portions continuously arranged along the circumferential direction of the second gear, and the first gear and the second gear rotate together according to the operation of the first motor, repeatedly applying pressure to the piston and releasing the pressure on the piston.

12. The method of claim 11, wherein the second gear is configured to slidably advance to press the piston when the second motor rotates in one direction, and slidably retreat to release pressure on the piston when the second motor rotates in an opposite direction. 13 . The method of claim 12 , wherein in a first mode in which an anti-lock braking system (ABS) is implemented, the control portion is configured to control the first motor to be driven while preventing the second motor from being driven. 14 . The method according to claim 12 , wherein in a second mode of stopping the vehicle, the controller is configured to control the second motor to rotate in the one direction. 15 . The method according to claim 12 , wherein in a third mode of applying emergency braking, the control portion is configured to control the first motor to drive in a direction in which the guide portion presses the piston, and control the second motor to rotate in the one direction.

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