Electric braking system and method for leak testing thereof

Abstract

A method for leak testing an electric brake system, comprising: a master cylinder (20) connected to an oil-storing reservoir (30) and configured to generate hydraulic pressure corresponding to a pedal force of a brake pedal (10); a simulation device (50) one side of which is connected to the master cylinder (20) to provide a reaction force corresponding to the pedal force of the brake pedal (10), and the other side of which is connected to the reservoir (30); a simulation valve (54) provided in a flow path connected to the master cylinder (20) or a flow path connected to the reservoir (30); a device (100) for supplying hydraulic pressure, actuated by an electrical signal from a pedal position sensor that detects a displacement of the brake pedal (10) and configured to generate hydraulic pressure; and a hydraulic pressure control unit (200) configured toto control the hydraulic pressure delivered by the main cylinder (20) and / or the device (10) for supplying hydraulic pressure, and to supply the hydraulic pressure to a wheel cylinder (40) provided at each wheel, comprising: , Performing a test mode to test for leakage of the simulation valve (54) and a sealing element (23) provided within a chamber of the main cylinder (20) by providing an inspection valve (60) in the flow path connecting the main cylinder (20) to the container (30), wherein the test mode includes: (a1) Closing a shut-off valve (261, 262) provided on a flow path connecting the main cylinder (20) to the hydraulic pressure control unit (200) when the inspection valve (60) is open; (b1) Applying a vacuum to a piston located in the master cylinder (20) according to a pedal force of the brake pedal (10) and detecting whether pressure is built up via a pressure sensor (PS1); and (c1) Determine that no leakage exists if the pressure detected via the pressure sensor (PS1) meets a certain criterion.

Description

BACKGROUND 1. Area

[0001] Exemplary embodiments of the present invention relate to an electric braking system, and in particular to an electric braking system that generates a braking force using an electrical signal corresponding to a displacement of a brake pedal, and a test method that is able to check whether a leakage of hydraulic pressure occurs using the same. 2. Description of the state of the art

[0002] A braking system is necessarily fitted to a vehicle, and a variety of systems for providing stronger and more stable braking have been proposed recently.

[0003] For example, there are braking systems that include an anti-lock braking system (ABS) to prevent wheels from slipping during braking, a brake traction control system (BTCS) to prevent a wheel from slipping when a vehicle is quickly started and accelerated, an electronic stability control system (ESC) to maintain a stable driving condition of a vehicle by combining an ABS with a traction control system to control the hydraulic pressure of a brake, and the like.

[0004] In general, an electric braking system includes a device for supplying hydraulic pressure, which receives a driver's braking intention in the form of an electrical signal from a pedal motion sensor that detects movement or displacement of a brake pedal when the driver presses the brake pedal, and then supplies hydraulic pressure to a wheel cylinder.

[0005] An electric braking system equipped with such a device for supplying hydraulic pressure is disclosed in European Patent No. EP 2 520 473. According to the disclosure in this document, the device for supplying hydraulic pressure is designed such that a motor is actuated in accordance with the pedal force of a brake pedal to generate brake pressure. At this point, the brake pressure is generated by converting a rotational force of the motor into a linear motion to apply pressure to a piston.

[0006] The electric braking system also includes a simulation device capable of delivering a reaction force to the driver corresponding to the pedal force applied to the brake pedal. At this point, the simulation device is connected to an oil reservoir, and a simulation valve is installed on an oil flow path connecting the simulation device to the reservoir. The simulation valve is designed to be closed when the electric braking system malfunctions and to supply hydraulic pressure, which is delivered from a master cylinder to the wheel cylinder, thus enabling stable braking.

[0007] However, in such an electric braking system there is a problem that if a leak occurs in a component that is provided in a hydraulic circuit connecting the master cylinder to the wheel cylinder, or in a component of the hydraulic circuit that connects the device for supplying hydraulic pressure to the wheel cylinder, a dangerous situation may arise if a braking force intended by the driver is not generated.

[0008] From the unpublished DE 10 2016 224 057, a method for leakage testing of an electric brake system is disclosed, comprising a master cylinder connected to an oil-storing reservoir, a simulation device whose one side is connected to the master cylinder and whose other side is connected to the reservoir, a simulation valve provided in a flow path connected to the master cylinder or a flow path connected to the reservoir, a device for supplying hydraulic pressure which is actuated by an electrical signal from a pedal travel sensor and is configured to generate hydraulic pressure, and a hydraulic pressure control unit which is configured to control hydraulic pressure delivered by the master cylinder and / or the device for supplying hydraulic pressure.The procedure includes a diagnostic mode in which shut-off valves, inlet and outlet valves present in the flow paths are opened and closed under specified boundary conditions and hydraulic pressures are measured, whereby an anomaly of the valves is diagnosed by comparison with reference pressures. [State of the art document]

[0009] (Patent document) European Patent No. EP 2 520 473 A1 (Honda Motor Co., Ltd.), 7 November 2012. DEMOLITION

[0010] The problem underlying the invention, namely to create an improved method for leakage testing, is solved by the features of the independent claims.

[0011] It is an aspect of the present invention to provide a method for leakage testing using a braking system which is capable of checking for leaks with respect to the hydraulic pressure of an electric braking system when a vehicle is stopped in order to prevent the occurrence of an accident.

[0012] Additional aspects of the revelation are partly listed in the following description and partly can be obviously derived from the description or can be gained by putting the revelation into practice.

[0013] In accordance with one aspect of the present invention, a method for leak testing of an electric brake system is provided, comprising a master cylinder connected to an oil-storing reservoir and configured to generate hydraulic pressure corresponding to a pedal force of a brake pedal, a simulation device, one side of which is connected to the master cylinder to provide a reaction force corresponding to the pedal force of the brake pedal, and the other side of which is connected to the reservoir, a simulation valve provided in a flow path connected to the master cylinder or a flow path connected to the reservoir, a device for supplying hydraulic pressure, actuated by an electrical signal from a pedal travel sensor that detects a displacement of the brake pedal and configured to generate hydraulic pressure, and a hydraulic pressure control unit configured toto control the hydraulic pressure delivered by the master cylinder and / or the hydraulic pressure delivery device and to supply the hydraulic pressure to a wheel cylinder provided at each wheel, comprising performing a test mode for leak testing of the simulation valve and a sealing element provided within a chamber of the master cylinder by providing an inspection valve in the flow path connecting the master cylinder to the reservoir, wherein the test mode includes: (a1) closing a shut-off valve provided on a flow path connecting the master cylinder to the hydraulic control unit when the inspection valve is open; (b1) applying a vacuum to a piston located in the master cylinder in accordance with a pedal force of the brake pedal and detecting whether pressure builds up via a pressure sensor; and (c1) determining that no leakage exists.when the pressure detected by the pressure sensor meets a certain criterion.

[0014] Furthermore, if the pressure detected via the pressure sensor in operation (c1) does not meet the specified criterion, determine that a leak has occurred in the simulation valve and / or the sealing element.

[0015] The procedure for leak testing an electric brake system also includes: (d1) returning the brake pedal to its original position; (e1) closing the inspection valve, the simulation valve, and the shut-off valve to change the chamber of the master cylinder to form a closed circuit; (f1) applying a vacuum to the piston located in the master cylinder according to a pedal force of the brake pedal and detecting whether pressure builds up via the pressure sensor; and (g1) determining that a leak has occurred at the sealing element if the pressure detected via the pressure sensor meets the predetermined criterion, and determining that a leak has occurred at the simulation valve if the pressure built up via the pressure sensor does not meet the predetermined criterion.

[0016] According to another aspect of the present invention, a method for leak testing of an electric brake system is provided, comprising a master cylinder (20) connected to an oil-storing reservoir and configured to generate hydraulic pressure corresponding to a pedal force of a brake pedal, a simulation device, one side of which is connected to the master cylinder to provide a reaction force corresponding to the pedal force of the brake pedal, a device for supplying hydraulic pressure, which is actuated by an electrical signal from a pedal travel sensor that detects a displacement of the brake pedal and is configured to generate hydraulic pressure, and a hydraulic pressure control unit configured to control the hydraulic pressure delivered by the master cylinder and / or the device for supplying hydraulic pressure and to supply the hydraulic pressure to a wheel cylinder provided at each wheel.comprising performing a test mode for leak testing of a sealing element provided within the chamber of the hydraulic pressure supply device and of a check valve located in a flow path connected to a reservoir at the outlet side of the hydraulic pressure supply device, by providing an inspection valve in a flow path connecting the reservoir to an oil port of the hydraulic pressure supply device, wherein the test mode comprises: (a2) closing a shut-off valve located in a flow path connecting the main cylinder to the hydraulic pressure control unit when the inspection valve is open; (b2) operating the hydraulic pressure supply device to pressurize and detect a hydraulic piston located within the hydraulic pressure chamber of the hydraulic pressure supply device.(c2) determine whether pressure is built up via the pressure sensor; and (c2) determine that no leakage exists if the pressure detected via the pressure sensor meets a certain criterion.

[0017] Furthermore, if the pressure detected via the pressure sensor in operation (c2) does not meet the predetermined criterion, determine that a leakage has occurred in the sealing element and / or the check valve.

[0018] The method for leak testing an electric brake system also includes: (d2) resetting the hydraulic piston of the hydraulic pressure supply device to its original position; (e2) closing the inspection valve and the shut-off valve to modify the hydraulic pressure chamber of the hydraulic pressure supply device to form a closed circuit; (f2) actuating the hydraulic pressure supply device to pressurize the hydraulic piston provided in the hydraulic pressure chamber of the hydraulic pressure supply device and detecting whether pressure is built up via the pressure sensor;and (g2) Determine that a leak has occurred at the sealing element if the pressure detected via the pressure sensor meets the specified criterion, and determine that a leak has occurred at the check valve if the pressure built up via the pressure sensor does not meet the specified criterion.

[0019] An electric braking system is used, comprising a reservoir configured to store oil, a master cylinder (20) having a first and a second hydraulic port and coupled to the reservoir to receive oil, a pedal position sensor configured to detect a displacement of a brake pedal, and a simulation device connected to the master cylinder and designed to supply a reaction force corresponding to a pedal force of the brake pedal, comprising: a device for supplying hydraulic pressure, configured to output an electrical signal corresponding to an actuation of the brake pedal via the pedal position sensor to actuate a motor and convert a rotational force of the motor into a linear motion;a hydraulic pressure control unit including a first and a second hydraulic circuit, which is connected to the device for supplying hydraulic pressure via a hydraulic flow path and is configured to receive hydraulic pressure by means of a force generated by the device for supplying hydraulic pressure, and which controls a flow of the hydraulic pressure supplied to wheel cylinders provided on the respective wheels;and an electronic control unit configured to control the motor and the valves based on hydraulic pressure information and pedal travel information, the electric brake system further comprising: an inspection valve including an internal flow path, one side of which is connected to the reservoir and the other side of which is arranged to be connected to the master cylinder 20 and the device for supplying hydraulic pressure via a branching flow path, and wherein the inspection valve is provided to open a flow path connecting the reservoir to the master cylinder and a flow path connecting the reservoir to the device for supplying hydraulic pressure in a braking mode, and to close the flow path connecting the reservoir to the master cylinder and / or the flow path connecting the reservoir to the device for supplying hydraulic pressure.

[0020] The hydraulic pressure control unit also includes: first to fourth inlet valves, each provided on an upstream side of the wheel cylinders and configured to control the pressure to be supplied to the respective wheel cylinders installed on the wheels; first to fourth outlet valves, each configured to control a flow of hydraulic pressure discharged from the wheel cylinder; and a first and second compensating valve, each arranged between the first to fourth inlet valves and the first to fourth outlet valves, the first compensating valve being connected to two of the inlet valves of the first to fourth inlet valves and the second compensating valve being connected to the remaining two inlet valves.

[0021] The two inlet valves connected to each other via the first balancing valve and one of the two inlet valves connected to each other via the second balancing valve are also open, so that hydraulic pressure is supplied to the wheel cylinders, which are installed on the wheels.

[0022] The first to fourth inlet valves are also equipped with normally closed solenoid valves, which are closed in the rest state and open when an opening signal is received.

[0023] The first to fourth drain valves are also equipped with normally closed solenoid valves, which are closed in the rest state and open when an opening signal is received.

[0024] The first and second balancing valves are also equipped with normally open solenoid valves, which are open in the rest state and close when a closing signal is received from the electronic control unit.

[0025] The electric braking system also includes: a first backup flow path configured to connect the first hydraulic port to the first compensating valve to supply oil directly to the wheel cylinders when the electric braking system malfunctions; a second backup flow path configured to connect the second hydraulic port to the second compensating valve; a first check valve provided in the first backup flow path and configured to control an oil flow therein; and a second check valve provided in the second backup flow path and configured to control an oil flow therein.

[0026] The first and second shut-off valves are also equipped with normally open solenoid valves, which are open in the rest state and close when a closing signal is received from the electronic control unit.

[0027] The inspection valve is also equipped with a normally open solenoid valve, which is open in the rest state and closes when a closing signal is received from the electronic control unit.

[0028] The electric braking system also includes: a first pressure sensor provided in a flow path connecting the master cylinder to the simulation device; and a second pressure sensor provided in a hydraulic flow path connecting the hydraulic pressure supply device and the hydraulic pressure control unit.

[0029] The device for supplying hydraulic pressure also comprises: a motor configured to generate a torque dependent on the electrical signal from the pedal position sensor; a power conversion unit configured to convert the torque of the motor into linear motion; a hydraulic piston connected to the power conversion unit and configured to perform linear motion; a hydraulic pressure chamber configured to allow the hydraulic piston to slide within it and connected to the first and second hydraulic circuits via the hydraulic flow path; a hydraulic spring provided within the hydraulic pressure chamber and configured to support the hydraulic piston, the hydraulic pressure chamber being configured to be connected to the reservoir via an oil port and to receive oil.A connecting hole is also provided to connect to the reservoir on an outlet side of the hydraulic pressure chamber, and a check valve is provided in a flow path connecting the connecting hole and the reservoir, designed to allow oil to flow from the reservoir to the hydraulic pressure chamber and to block the flow of oil from the hydraulic pressure chamber to the reservoir.

[0030] The simulation valve and a simulation check valve are also provided in parallel in a flow path that connects a rear end of a simulation chamber of the simulation device to the container.

[0031] The simulation valve is also designed with a normally closed solenoid valve, which is closed in the rest position and opens when an opening signal is received. BRIEF DESCRIPTION OF THE DRAWING Fig. Figure 1 is a circuit diagram of a hydraulic circuit representing a non-braking state of an electric braking system according to an embodiment of the present disclosure: Fig. Figure 2 is a circuit diagram of a hydraulic circuit representing a state in which the electric braking system normally performs a braking operation according to an embodiment of the present disclosure. Fig. Figure 3 is a circuit diagram of a hydraulic circuit, representing a case of releasing a braking force in a braking condition when the electric braking system is operating normally. Fig. 4 is a circuit of a hydraulic circuit that represents a case of braking only one corresponding wheel cylinder when an anti-lock braking system (ABS) is operating. Fig. Figure 5 is a circuit diagram of a hydraulic circuit representing a case in which the electric braking system operates in a drain mode and releases hydraulic pressure from only one corresponding wheel cylinder. Fig. Figure 6 is a circuit diagram of a hydraulic circuit representing a case in which the electric braking system operates anomalously according to an embodiment of the present disclosure. Fig. 7 and Fig. Figure 8 are circuit diagrams of hydraulic circuits representing a state of testing whether a leakage occurs in an electric braking system according to another embodiment of the present disclosure. Fig. 9 and Fig. Figure 10 are circuit diagrams of hydraulic circuits that represent a state of testing whether a leakage occurs in an electric braking system according to yet another embodiment of the present disclosure. DETAILED DESCRIPTION

[0032] The following describes exemplary embodiments of the present disclosure in detail with reference to the accompanying drawing. Dimensions of the components may be exaggerated in the drawing to facilitate understanding.

[0033] Fig. Figure 1 is a circuit diagram of a hydraulic circuit showing a non-braking state of an electric braking system according to an embodiment of the present disclosure.

[0034] Referring to Fig. 1 The electric braking system generally comprises a master cylinder 20 configured to generate hydraulic pressure, a reservoir 30 for storing oil connected to an upper part of the master cylinder 20, an input rod 12 configured to pressurize the master cylinder 20 according to a pedal force of a brake pedal 10, a wheel cylinder 40 configured to receive hydraulic pressure and to brake each of the wheels RR, RL, FR and FL, a pedal travel sensor 11 configured to detect a displacement or movement of the brake pedal 10, and a simulation device 50 configured to provide a reaction force according to the pedal force of the brake pedal 10.

[0035] The master cylinder 20 can be configured to enclose at least one chamber and generate hydraulic pressure. As shown in the drawing, the master cylinder 20 can be configured to enclose two chambers 25a and 25b. A first piston 21a and a second piston 22a are each provided in the two chambers 25a and 25b, and the first piston 21a and the input rod 12 are in contact with each other. The reason for providing the two chambers 25a and 25b in the master cylinder 20 is to ensure safety even if one of the two chambers 25a and 25b fails. For example, the first chamber 25a of the two chambers 25a and 25b is connected to a front right wheel FR and a rear left wheel RL, and the second chamber 25b is connected to a front left wheel FL and a rear right wheel RR.Alternatively, the first chamber 25a of the two chambers 25a and 25b can be connected to the two front wheels FR and FL, and the second chamber 25b can be connected to the two rear wheels RR and RL. As described above, the reason for the independent design of the two chambers 25a and 25b is to enable braking of the vehicle even if one of the two chambers 25a and 25b fails. A first and a second hydraulic port 24a and 24b, designed to release hydraulic pressure from the first and second chambers 25a and 25b respectively, are provided on the master cylinder 20.

[0036] A first spring 21b is also provided between the first piston 21a and the second piston 22a of the master cylinder 20, and a second spring 22b is provided between the second piston 22a and one end of the master cylinder 20. That is, the first spring 21b and the second spring 22b are each located at the two chambers 25a and 25b to store an elastic force when the first piston 21a and the second piston 22a are compressed. If a force pushing the first piston 21a is less than the elastic force, the elastic force pushes the first and second pistons 21a and 22a back to their original positions.

[0037] Furthermore, the master cylinder 20 includes a sealing element 23 designed to seal a gap between an inner surface of the master cylinder 20 and an outer surface of each of the two chambers 25a and 25b. The sealing element 23 prevents oil from penetrating through a gap between an inner circumferential surface of the master cylinder 20 and each of the two pistons 21a and 22a, which could generate high hydraulic pressure. The sealing element can be provided on both sides of each part connected to the reservoir 30 and can be installed in receiving recesses (not shown) formed on an inner surface of the master cylinder 20 to prevent the sealing element 23 from moving, even when the first and second pistons 21a and 22a move forward and backward.

[0038] Meanwhile, the input rod 12, which pressurizes the first piston 21a of the master cylinder 20, comes into close contact with the first piston 21a, so that there is no gap between the master cylinder 20 and the input rod 12. This means that when the brake pedal is pressed, the master cylinder 20 can be pressurized directly without any pedal travel.

[0039] The simulation device 50 is connected to a first backup flow path 251, described below, to provide a reaction force corresponding to the pedal force of the brake pedal. As shown in the drawing, the simulation device 50 comprises a simulation chamber 51, designed to store oil drained from the first hydraulic port 24a of the master cylinder 20; a reaction force piston 52 located within the simulation chamber 51; a pedal simulator equipped with a reaction force spring 53 that elastically supports the reaction force piston 52; and a simulation valve 54 connected to a rear end region of the simulation chamber. From this point onward, the reaction force piston 52 and the reaction force spring 53 are each positioned to have a predetermined displacement range within the simulation chamber 51 due to the oil flowing therein.

[0040] Meanwhile, the reaction force spring 53 shown in the drawing is only one embodiment capable of applying an elastic force to the reaction force piston 52, and numerous embodiments capable of storing an elastic force through deformation may be included. As an example, the reaction force spring 53 comprises a plurality of elements that store an elastic force by being formed with a material including rubber or the like, or by having a spiral or plate shape.

[0041] The simulation valve can be provided in a flow path that connects a rear end of the simulation chamber 51 to the container 30. That is, an inlet of the simulation chamber 51 is connected to the main cylinder 20, the rear end of the simulation chamber 51 is connected to the simulation valve 54, and the simulation valve 54 is connected to the container 30. Therefore, when the reaction force piston 52 is returned to its original position, oil within the container 30 can flow through the simulation valve 54, so that the interior of the simulation chamber 51 can be completely filled with oil.

[0042] Such a simulation valve 54 is designed as a normally closed solenoid valve, which assumes a closed state in its resting position. When the driver presses the brake pedal 10, the simulation valve 54 opens to supply brake fluid to the simulation chamber 51.

[0043] A simulation check valve 55 can also be installed in parallel with the simulation valve 54 between the simulation device 50 and the container 30. The simulation check valve 55 can be configured to allow the oil within the container 30 to flow only to the simulation chamber 51. That is, the reaction force piston 52 of the pedal simulator compresses the reaction force spring 53 such that oil within the simulation chamber 51 is supplied to the container 30 via the simulation valve 54. Since the interior of the simulation chamber 51 is thus filled with oil, the friction of the reaction force piston 52 is minimized when the simulation device 50 is actuated, thereby improving the service life of the simulation device 50 and also providing a blockage against the ingress of foreign materials from the outside.

[0044] When the pedal force of the brake pedal 10 is additionally released, oil is supplied within the simulation chamber 51 via the simulation check valve 55 to ensure a rapid return of the pressure of the pedal simulator.

[0045] The electric braking system according to an embodiment of the present disclosure comprises a device 100 for supplying hydraulic pressure, which is mechanically operated by receiving a braking intention of the driver in the form of an electrical signal from the pedal travel sensor 11, which detects a displacement of the brake pedal 10; a hydraulic pressure control unit 200, which is configured with a first and a second hydraulic circuit 201, 202, each assigned to two wheels and which controls a flow of hydraulic pressure supplied to the wheel cylinders 40, each provided at wheels RR, RL, FR and FL; a first check valve 261, which is provided in the first backup flow path 251, which connects the first hydraulic port 24a to the first hydraulic circuit 201 to control a flow of hydraulic pressure therein; and a second check valve 262.which is provided in a second backup flow path 252, which connects the second hydraulic port 24b to the second hydraulic circuit 202 to control a flow of hydraulic pressure therein, and an electrical control unit (ECU) (not shown) configured to control the device 100 for supplying hydraulic pressure and valves 54, 60, 221, 222, 223, 224, 231, 232, 241, 242, 261 and 262 on the basis of the hydraulic pressure information and the pedal displacement information.

[0046] The device 100 for supplying hydraulic pressure comprises a hydraulic pressure chamber 110 in which a predetermined space is formed for receiving and storing oil, a hydraulic piston 120 and a hydraulic spring 122 provided within the hydraulic pressure chamber 110, a motor 140 configured to generate a rotary force dependent on an electrical signal from the pedal position sensor 11, and a power conversion unit 130 configured to convert a rotary motion of the motor 140 into a linear motion in order to move the hydraulic piston 120 in a linear motion. At this point, the reservoir 30 and the hydraulic pressure chamber 110 are connected to each other by an oil flow path 101 to supply oil to the hydraulic pressure chamber 110.Here, a signal sampled by the pedal position sensor 11 is transmitted to the ECU (not shown), and the ECU controls the motor 140 and the valves provided in the electric brake device of this disclosure, as described below. A control operation of a plurality of valves corresponding to a displacement of the brake pedal 10 is described below.

[0047] The hydraulic pressure chamber 110 is connected to the reservoir 30 via the oil flow path 101 and receives and stores the oil. The oil flow path 101 is connected to an oil port 111, which is formed on an inlet side of the hydraulic pressure chamber 110. A sealing element 113 is provided inside the hydraulic pressure chamber 110 and comes into contact with the hydraulic piston 120 to prevent oil from escaping. The sealing element 113 is installed on both sides of the oil port 111, which is connected to the oil flow path 101, within the hydraulic pressure chamber 110.

[0048] A check valve 112 is also installed so that it is continuously connected to an outlet side of the hydraulic pressure chamber 110 to prevent oil pressure from flowing back to an oil supply flow path 102 connected to the reservoir 30. The check valve 112 shuts off oil within the hydraulic pressure chamber 110 so that it is not lost to the reservoir 30 when the hydraulic piston 120 moves forward, and causes the oil to be drawn in and stored in the hydraulic pressure chamber 110 when the hydraulic piston 120 returns.

[0049] The hydraulic pressure 120, which pressurizes the hydraulic pressure chamber 110, is connected to the power conversion unit 130, which converts the rotational force of the motor 140 into linear motion, and slides within the hydraulic pressure chamber 110.

[0050] The power conversion unit 130 is a device that converts a rotational force into linear motion and can be configured with a ball screw nut assembly. For example, the power conversion unit 130 can be configured with a spindle that is integrally formed with a rotating shaft (not shown) of the motor 140, and a ball nut that is screw-coupled to the spindle in a state where rotation of the ball nut is limited to perform linear motion corresponding to a rotation of the spindle. That is, the spindle serves as the rotating shaft of the motor 140 and also serves to linearly move the ball nut.The hydraulic piston 120 is connected to the ball nut of the power conversion unit 130 to pressurize the hydraulic pressure chamber 110 by the linear movement of the ball nut, and the hydraulic spring 122 serves to return the hydraulic piston 120 to its original position, with the ball nut returning to its original position.

[0051] While the hydraulic piston 120 returns to its original position, the hydraulic pressure chamber 110 and the reservoir 30 communicate with each other. For example, the oil inside the reservoir flows into the hydraulic pressure chamber 110 and prevents a negative pressure from forming.

[0052] Meanwhile, although not shown in the drawing, the power conversion unit 130 can be configured with a ball nut that is rotated by receiving a rotational force from the rotating shaft of the motor 140, and a spindle that is screw-coupled to the ball nut in a state where rotation of the spindle is restricted to execute a linear motion corresponding to a rotation of the ball nut. Such a ball screw nut assembly is a device that converts rotary motion into linear motion, and since its construction is generally known in the prior art, a detailed description is omitted here. It should also be noted that, according to the present disclosure, the power conversion unit 130 can use any structure capable of converting rotary motion into linear motion instead of the ball screw nut assembly structure.

[0053] Motor 140 is an electric motor for generating rotational force in response to a signal output by the ECU. The ECU controls the rotational force in either a forward or reverse direction. Precise control can be achieved by adjusting the rotation angle or speed of Motor 140. Since such a motor 140 is generally known in the prior art, a detailed description is omitted.

[0054] As an example of a device 100 for supplying hydraulic pressure, a single-acting piston is shown in the drawing, with which the single hydraulic pressure chamber 110 and the single hydraulic piston 120 are provided. In contrast to the drawing, the device 100 for supplying hydraulic pressure can include a double-acting piston, with which a pair of hydraulic pressure chambers are provided on both sides of a single hydraulic piston, and a tandem piston can be included, with which a pair of hydraulic pressure chambers is provided on one side of each of the pairs of hydraulic pistons.

[0055] The hydraulic pressure control unit 200 is configured with a first hydraulic circuit 201 and a second hydraulic circuit 202, each of which receives hydraulic pressure and controls two wheels. As shown in the drawing, hydraulic circuit 201 can control the right front wheel (FR) and the left rear wheel (RL), and the second hydraulic circuit 202 can control the left front wheel (FL) and the right rear wheel (RR). The wheel cylinder 40 is installed at each of the wheels (FR, FL, RR, and RL) and performs braking by receiving hydraulic pressure.That is, the hydraulic pressure control unit 200 receives the hydraulic pressure from the device 100 to supply hydraulic pressure via a main hydraulic flow path 210, which is connected to the first and second hydraulic circuits 201 and 202, and the first and second hydraulic circuits 201 and 202 comprise a plurality of valves 221, 222, 223, 224, 231, 232, 233, 234, 241 and 242 to control a flow of hydraulic pressure.

[0056] The first hydraulic circuit 201 comprises a first 221 and a second 222 inlet valve, which are connected to the main hydraulic flow path 210 and are configured to control the hydraulic pressure supplied to the wheel cylinders 40, a first 231 and a second 232 outlet valve, which are configured to control an oil flow supplied by the wheel cylinders 40 provided in the first hydraulic circuit 201, and a first balancing valve 224, which is configured to connect and block a flow path between the two wheel cylinders 40, which are connected to the first inlet valve 221 and the second inlet valve 222.More precisely, the first inlet valve 221 is located in a first hydraulic flow path 211, which is connected to the main hydraulic flow path 210 and the right front wheel FR, and the second inlet valve 222 is located in a second hydraulic flow path 212, which is connected to the main flow path 210 and the left rear wheel RL. The first outlet valve 231 is connected to the first hydraulic flow path 211 and controls the hydraulic pressure delivered by the wheel cylinder 40 of the right front wheel FR, and the second outlet valve 232 is connected to the second hydraulic flow path and controls the hydraulic pressure delivered by the wheel cylinder 40 of the left rear wheel RL.The first balancing valve 241 is provided in a flow path that connects the first hydraulic flow path 211 with the second flow path 212 and serves to connect or shut off the first and second flow paths 211, 212 according to opening and closing operations.

[0057] The second hydraulic circuit 202 comprises a third 223 and a fourth 224 inlet valve, which are connected to the main hydraulic flow path 210 and are configured to control the pressure supplied to the wheel cylinders 40; a third 233 and a fourth 234 drain valve, which are configured to control an oil flow that is drained from the wheel cylinders 40 provided in the second hydraulic circuit 202; and a second balancing valve 242, which is configured to connect and shut off a flow path between the two wheel cylinders 40 that are connected to the third inlet valve 223 and the fourth inlet valve 224.More precisely, the third inlet valve 223 is provided in a third hydraulic flow path 213, which is connected to the main hydraulic flow path 210 and the right rear wheel RR, and the fourth inlet valve 224 is provided in a fourth hydraulic flow path 214, which is connected to the main hydraulic flow path 210 and the left front wheel FL. The third outlet valve 233 is connected to the third hydraulic flow path 213 and controls the hydraulic pressure delivered by the wheel cylinder 40 of the right rear wheel RR, and the fourth outlet valve 234 is connected to the fourth hydraulic flow path 214 and controls the hydraulic pressure delivered by the wheel cylinder 40 of the left front wheel FL.The second balancing valve 242 is provided in a flow path that connects the third hydraulic flow path 213 with the fourth hydraulic flow path 214 and serves to connect or shut off the third and fourth hydraulic flow paths 213, 214 according to opening and closing operations.

[0058] Meanwhile, an example has been shown and described in which the first balancing valve 241 is connected to the first and second intake valves 221, 222, and the second balancing valve 242 is connected to the third and fourth intake valves 223, 224, but the present disclosure is not limited to this. Alternatively, the first balancing valve 241 can be connected to two intake valves, from the first to the fourth intake valves 221, 222, 223, and 224, and the second balancing valve 242 can be connected to the remaining two intake valves. That is to say, the first balancing valve 241 can be connected to the first and second intake valves 221 and 223, or to the first and fourth intake valves 221 and 224.It is understood that such a connection structure between the balancing valves 241, 242 and the inlet valves 221, 222, 223 and 224 can be selectively modified and used according to a user requirement or system configuration.

[0059] The opening and closing operations of each of the first to fourth inlet valves 221, 222, 223, and 224 are controlled independently of the ECU to deliver the hydraulic pressure generated at the hydraulic pressure supply device 100 to the wheel cylinders 40. That is, the first and second inlet valves 221 and 222 are configured to control the hydraulic pressure supplied to the first hydraulic circuit 201, and the third and fourth inlet valves 223 and 224 are configured to control the hydraulic pressure supplied to the second hydraulic circuit 202.

[0060] The opening and closing operations of each of the first to fourth drain valves 231, 232, 233 and 234 are also controlled independently by the ECU. The first and second drain valves 231 and 232 are configured to control the hydraulic pressure delivered by the wheel cylinders 40 of the first hydraulic circuit 201, and the third and fourth drain valves 233 and 234 are configured to control the hydraulic pressure delivered by the wheel cylinders 40 of the second hydraulic circuit 202.

[0061] In accordance with an embodiment of the present invention, two of the four inlet valves 221, 222, 223 and 224 can be configured to open, so that hydraulic pressure is supplied to the wheel cylinders 40 of each of the wheels FR, FL, RR and RL. As, for example, in Fig. As shown in Figure 2, the first inlet valve 221 of the first and second inlet valves 221 and 222 is open, and the fourth inlet valve 224 of the third and fourth inlet valves 223 and 224 is open, so that hydraulic pressure is supplied to the wheel cylinders 40 of each of the wheels FR, FL, RR, and RL. That is, the hydraulic pressure passing through the first and fourth inlet valves 221 and 224 is supplied to adjacent wheel cylinders 40 via the first and second balancing valves 241 and 242. An example is shown here in which the first hydraulic circuit 201 and the second hydraulic circuit 202 open the inlet valves 221 and 224 to supply hydraulic pressure to each of the wheel cylinders 40, but the present disclosure is not limited thereto.Alternatively, and depending on the configuration of the flow path connection, the two inlet valves 221 and 222 provided in the first hydraulic circuit 201, or the two inlet valves 223 and 224 provided in the second hydraulic circuit 202, can be opened to supply hydraulic pressure to each of the wheel cylinders 40. If emergency braking is required, the inlet valves 221, 222, 223, and 224 can be opened to quickly supply hydraulic pressure to the wheel cylinders 40.

[0062] Such first to fourth inlet valves 221, 222, 223 and 224 are equipped with normally closed solenoid valves which are closed in the rest state and are opened when an opening signal is received.

[0063] The first and second balancing valves 241 and 242 are also designed with normally open solenoid valves, which are open in the rest state and are closed when a closing signal is received from the ECU, and the first to fourth drain valves 231, 232, 233 and 234 are designed with normally closed solenoid valves, which are closed in the rest state and are opened when an opening signal is received.

[0064] In accordance with one aspect of the present disclosure, the first and second backup flow paths 251 and 252 are provided to supply oil delivered from the master cylinder 20 to the wheel cylinders 40 when the electric brake system malfunctions. More precisely, the first check valve 261, designed to control oil flow, is provided in the first backup flow path 251, and the second check valve 262, designed to control oil flow, is provided in the second backup flow path 252. The first backup flow path 251 connects the first hydraulic port 24a to the first hydraulic circuit 201, and the second backup flow path 252 connects the second hydraulic port 24b to the second hydraulic circuit 202.As shown in the drawing, the first backup flow path 251 is connected to the first balancing valve 241, which connects the first hydraulic flow path 211 to the second hydraulic flow path 212, and the second backup flow path 252 is connected to the second balancing valve 242, which connects the third hydraulic flow path 213 to the fourth hydraulic flow path 214. The design and operation of the first and second check valves 261 and 262 are described in more detail below.

[0065] The first and second shut-off valves 261 and 262 are designed with normally open solenoid valves that are open in the rest state and close when a closing signal is received from the ECU.

[0066] Meanwhile, an unspecified reference 'PS1' is a first pressure sensor that senses the oil pressure of the master cylinder 20, and an unspecified reference 'PS2' is a second pressure sensor that senses the hydraulic pressure output by the device 100 for supplying hydraulic pressure to the wheel cylinders 40. Also unspecified, '60' is an inspection valve that includes an internal flow path, one side of which is connected to the reservoir 30 and the other side of which is connected to the master cylinder 20 and the device 100 for supplying hydraulic pressure via a branch flow path. The inspection valve 60 is configured with a normally open solenoid valve that is open in the resting state and closes when the closing signal is received from the ECU. The inspection valve 30 is intended to check for leakage in the electric brake system and is described further below.

[0067] The following describes in detail the operation of the electric braking system according to an embodiment of the present disclosure.

[0068] Fig. Figure 2 is a hydraulic circuit diagram representing a state in which the electric braking system normally performs a braking operation according to an embodiment of the present disclosure.

[0069] If with reference to Fig. 2. When a driver begins to brake, the braking force requested by the driver can be sampled via the pedal travel sensor 11 based on information including pressure applied by the driver to the brake pedal 10 or the like. The ECU (not shown) receives an electrical signal output by the pedal travel sensor 11 and actuates the motor 140.

[0070] The ECU can also receive an amount of regenerative braking via the first pressure sensor PS1, which is provided on the outlet side of the master cylinder 20, and the second pressure sensor PS2, which is provided on the main hydraulic flow path 210, and can calculate an amount of brake friction based on a difference between the force of braking requested by the driver and the amount of regenerative braking in order to determine the magnitude of an increase or decrease in pressure at each of the wheel cylinders 40.

[0071] When the driver presses the brake pedal 10 at the beginning of braking, the motor 140 is actuated, a rotational force from the motor 140 is converted into linear motion by the power conversion unit 130, and the hydraulic piston 120 is moved forward to pressurize the hydraulic pressure chamber 110 to generate hydraulic pressure. That is, the hydraulic pressure released by the hydraulic pressure chamber 110 is delivered to the wheel cylinders 40 via the first to fourth hydraulic flow paths 211, 212, 213, and 214, each of which is connected to the main hydraulic flow path 210.In this case, the first and second shut-off valves 261 and 262, which are each installed in the first and second backup flow paths 251 and 252, which are each connected to the first and second hydraulic ports 24a and 24b, are closed, so that hydraulic pressure generated in the main cylinder 20 is not supplied to the wheel cylinders 40.

[0072] Furthermore, the pressure generated by the hydraulic pressure chamber 110 is supplied to the wheel cylinders of the right front wheel FR and the left front wheel FL according to the opening of the first and fourth inlet valves 221 and 224, respectively, to generate a braking force. At the same time, the hydraulic pressure supplied via the first and fourth inlet valves 221 and 224 is supplied to the wheel cylinders 40 of the left rear wheel RL and the right rear wheel RR via the first and second compensating valves 241 and 242, which are open. That is, the hydraulic pressure is supplied to all wheel cylinders 40 via the opening operation of the two inlet valves 221 and 224 selected from the four inlet valves 221, 222, 223, and 224.

[0073] Such an operation is a general braking operation and if an emergency braking is required, all inlet valves 221, 222, 223 and 224 can be opened to quickly supply hydraulic pressure to the wheel cylinders 40.

[0074] Meanwhile, the pressure generated by the vacuuming of the master cylinder 20, corresponding to the pedal force of the brake pedal 10, is supplied to the simulation device 50, which is connected to the master cylinder 20. This opens the normally closed simulation valve 54, located at the rear end of the simulation chamber 51, allowing the oil filling the simulation chamber 51 to be supplied to the reservoir 30 via the simulation valve 54. The reaction force piston 52 is also moved, and pressure corresponding to a reaction force of the reaction force spring 53, which supports the reaction force piston 52, is generated in the simulation chamber 51 to provide the driver with a suitable pedal feel.

[0075] Next, a case of releasing a braking force in a braking condition, which is created when the electric braking system is operating normally as described above, will be considered with reference to Fig. 3 described. If, as in Fig. As shown in Figure 3, when a pedal force applied to the brake pedal 10 is released, the motor 140 generates a rotational force in the opposite direction compared to when the hydraulic piston 120 is moved forward, in order to move the hydraulic piston 120 backward and return it to its original position. The opening and closing operating states of the first to fourth inlet valves 221, 222, 223 and 224, the first to fourth outlet valves 231, 232, 233 and 234, and the first and second balancing valves 241 and 242 are controlled in the same way as during braking operation. This means that the first to fourth exhaust valves 231, 232, 233 and 234 and the first and third inlet valves 222 and 223 are closed, whereas the first and fourth inlet valves 221 and 224 are open.As a result, hydraulic pressure released from the wheel cylinders 40 of the first hydraulic circuit 201 is supplied to the hydraulic pressure chamber 110 via the first balancing valve 241 and the first inlet valve 221, and hydraulic pressure released from the wheel cylinders 40 of the second hydraulic circuit 202 is supplied to the hydraulic pressure chamber 110 via the second balancing valve 242 and the fourth inlet valve 224.

[0076] In the simulation device 50, the oil present in the simulation chamber 51 is supplied to the main cylinder 20 according to the reaction force piston 52, which is returned to its original position by the reaction force spring 53, and the interior of the simulation chamber 51 is refilled with oil via the simulation valve 54 and the simulation check valve 55, which are connected to the reservoir 30 to ensure a rapid return of pressure to the pedal simulator.

[0077] When the hydraulic piston 120 is moved via the device 100 to supply hydraulic pressure to the electric brake system, an oil flow in the hydraulic pressure chamber 110 is controlled via the oil flow path 101 and the oil supply flow path 102, which are connected to the reservoir 30.

[0078] Furthermore, according to an embodiment of the present invention, the electric braking system can control the valves 221, 222, 223, 224, 231, 232, 233, 234, 241 and 242, which are provided in the hydraulic pressure control unit 200, according to a pressure specified for the wheel cylinders 40 of the two hydraulic circuits 201 and 202 provided at each of the wheels RR, RL, FR and FL, thereby controlling and specifying a control range. For example, Fig. Figure 4 shows a case of braking only one corresponding wheel cylinder while an anti-lock braking system (ABS) is actuated, and a state of braking only the left wheels FL and RL.

[0079] Referring to Fig. 4. The motor 140 is actuated according to a pedal force of the brake pedal 10, a rotational force of the motor is converted into a linear motion, and the hydraulic piston 120 is moved forward to pressurize the hydraulic pressure chamber 110 to generate hydraulic pressure. During this process, the first and second shut-off valves 261 and 262 are closed, so that the pressure generated in the master cylinder 20 is not supplied to the wheel cylinders 40. The first and third inlet valves 221 and 223, the first to fourth outlet valves 231, 232, 233, and 234, and the first and second balancing valves 241 and 242 are also controlled to close. Consequently, the hydraulic pressure generated by the hydraulic pressure chamber 110 is supplied to the wheel cylinder 40 of the left rear wheel RL via the second inlet valve 222 and to the wheel cylinder 40 of the left front wheel FL via the fourth inlet valve 224.Therefore, hydraulic pressure is only supplied to the left wheels RL and FL of all wheels RL, RR, FL and FR.

[0080] In accordance with one aspect of the present disclosure, the operations of the first to fourth inlet valves 221, 222, 223 and 224, the first to fourth outlet valves 231, 232, 233 and 234 and the first and second balancing valves 241 and 242 can be controlled independently, as described above, so that the hydraulic pressure is supplied only to the rear wheels RR and RL or to the wheel cylinders 40 of the right front wheel FR and the right rear wheel RR or of the right front wheel FR and the left rear wheel RL that require the hydraulic pressure.

[0081] According to the present disclosure, the electric braking system can also release brake pressure from only one corresponding wheel cylinder 40 via the first to fourth release valves 231, 232, 233 and 234 of the wheel cylinders 40 to which the brake pressure was supplied. For example, it shows Fig. Figure 5 shows a case in which the electric brake system operates in a draining mode and hydraulic pressure is output only from a corresponding wheel cylinder 40, and a case of draining only the left wheels RL and FL.

[0082] Referring to Fig. 5. The second and fourth inlet valves 222 and 224, the first and third outlet valves 231 and 233, and the first and second equalizing valves 241 and 242 are controlled to close, while the second and fourth outlet valves 232 and 234 are open. Consequently, the hydraulic pressure output from the wheel cylinders 40, installed on the left rear wheel RL and the left front wheel FL, is delivered to the reservoir 30 via the second and fourth outlet valves 232 and 234. During this process, the first and third inlet valves 221 and 223 are opened in conjunction with the outlet valves, in which the hydraulic pressure from the corresponding wheel cylinder 40 is released in accordance with the opening of the second and fourth outlet valves 232 and 234, thus delivering hydraulic pressure to the right front wheel FR and the right rear wheel RR.

[0083] As described above, each of the valves 221, 222, 223, 224, 231, 232, 233, 234, 241 and 242 of the hydraulic pressure control unit 200 can be independently controlled to selectively supply hydraulic pressure to or be supplied by the wheel cylinders 40 of each of the wheels RL, RR, FL and FR according to a required pressure, so that precise control of the hydraulic pressure is possible.

[0084] Finally, a case is described in which the electric braking system is working anomalously. Fig. Figure 6 is a circuit diagram of a hydraulic circuit representing a case in which the electric braking system operates anomalously according to an embodiment of the present invention.

[0085] When referring to Fig. 6. If the electric braking system is operating abnormally, each of the valves 54, 60, 221, 222, 223, 224, 231, 232, 233, 234, 241, 242, 261, and 262 is provided in a braking initial state, that is, in a non-actuated state. When a driver presses the brake pedal 10, the input rod 12, which is connected to the brake pedal 10, is moved in a leftward direction, and at the same time, the first piston 21a, which comes into contact with the input rod 12, is moved in a leftward direction, and the second piston 22a is also moved by the first piston 21a in a leftward direction. Since there is no gap between the input rod 12 and the first piston 21a, braking can be carried out quickly.

[0086] Furthermore, the hydraulic pressure generated by the vacuuming of the main cylinder 20 is supplied to the wheel cylinders 40 via the first and second backup flow paths 251 and 252, which are connected in a backup mode to generate a braking force for the purpose of braking. Here, the first and second shut-off valves 261 and 262, each installed in the first and second backup flow paths 251 and 252, and the first and second balancing valves 241 and 242, each installed in the first and second backup flow paths 251 and 252, are designed with normally open solenoid valves, and the simulation valve 54, the first to fourth inlet valves 221, 222, 223 and 224, and the first to fourth outlet valves 231, 232, 233 and 234 are designed with normally closed solenoid valves, so that the hydraulic pressure is supplied directly to the wheel cylinders 40. Therefore, braking is achieved stably to improve braking safety.

[0087] A test procedure for checking whether a hydraulic pressure leak occurs via an electric brake system with the setup described above is described. This test procedure includes a first test mode to check whether a leak occurs at the simulation valve 54, the simulation check valve 55, and the sealing element 23, which is provided within chambers 25a and 25b of the master cylinder 20. A second test mode checks whether a leak occurs at the sealing element 113, which is provided within the hydraulic pressure chamber 110 of the hydraulic pressure supply device 100, and at the check valve 112, which is located in the oil supply flow path 102 connected to the reservoir 30 to ensure continuous flow to the outlet side of the hydraulic pressure supply device 100. The first and second test modes are described below.

[0088] First, a test mode is used, that is, the first test mode to check whether there is a leak at the simulation valve 54, the simulation check valve 55 and the sealing element 23, which is provided within the chambers 25a and 25b of the main cylinder 20, with reference to the Fig. 7 and Fig. 8 described.

[0089] Fig. Figure 7 is a circuit diagram of a hydraulic circuit representing a state of testing whether a leakage occurs in an electric braking system according to another embodiment of the present disclosure.

[0090] Referring to Fig. In Figure 7, the inspection valve 60 is provided in a flow path connecting the master cylinder 20 to the reservoir 30 in the electric brake system. The inspection valve 60 can be installed between the reservoir 30 and the first chamber 25a, which is located between the first piston 21a and the second piston 22a of the master cylinder 20, to control the hydraulic pressure supplied between the reservoir 30 and the master cylinder 20. The inspection valve 60 can be configured with a normally open solenoid valve, which is open in the resting state and closes when a closing signal is received.

[0091] The test procedure for the electric brake system, including inspection valve 60, can be performed when the vehicle is stopped. First, with inspection valve 60 open, the first and second check valves 261 and 262, located in the flow paths (i.e., the first and second backup flow paths 251 and 252, which connect the master cylinder 20 to the hydraulic pressure control unit 200), are closed. This configuration is identical to that of a general braking mode.

[0092] Next, the first piston 21a, located in the master cylinder 20, is pressurized according to a pedal force applied to the brake pedal. The first pressure sensor PS1 detects whether pressure is generated. If pressure is generated in the master cylinder 20, it is determined that no leakage has occurred and the first test mode is terminated. If, however, no pressure is generated in the master cylinder 20, or if the generated pressure is less than a specified pressure value, it is determined that a leakage has occurred at the simulation valve 54 and / or the simulation check valve 55 and / or the sealing element 23, and the subsequent test is performed.

[0093] For example, if no pressure is built up, the brake pedal is returned to its original position. That is, the first piston 21a is returned to its original position. After that, as described in Fig. As shown in Figure 8, the inspection valve 60 and the shut-off valves 261 and 262 are closed, so that chambers 25a and 25b in the master cylinder 20 are modified to form a closed circuit. The reason for closing the inspection valve 60 and the shut-off valves 261 and 262 is that it is difficult to identify whether a leak occurs when the hydraulic pressure generated in the master cylinder 20 flows into the reservoir 30 via the inspection valve 60 or into the wheel cylinders 40 via the shut-off valves 261 and 262, resulting in a loss of pressure.

[0094] In a state where the inspection valve 60 and the shut-off valves 261 and 262 are closed, the first piston 21a, located in the master cylinder 20, is pressurized by the pedal force of the brake pedal 10, and the first pressure sensor PS1 is used to detect whether pressure is being generated. That is, a leakage component is detected according to the reading by the first pressure sensor PS1 as to whether pressure is being generated.

[0095] For example, it is determined that a leak has occurred at the sealing element 23 if the first pressure sensor PS1 detects that pressure has formed, while it is determined that a leak has occurred at the simulation valve 54 or the simulation check valve 55 if the first pressure sensor PS1 does not detect that pressure has formed.The reason for this is that hydraulic pressure is not formed when hydraulic pressure escapes into the simulation valve 54 and the simulation check valve 55, when the hydraulic pressure is formed again in a state where the pressure was not formed during an initial test, and the closed circuit between the reservoir 30 and the main cylinder 20 is provided by the inspection valve 60, even if the hydraulic pressure escapes through the sealing element 23, so that the hydraulic pressure is formed, and it is determined that a leakage has occurred at the sealing element 23.

[0096] Next, the second test mode is used to check whether there is a leak at the sealing element 113, which is provided in the hydraulic pressure chamber 110 of the device 100 for supplying hydraulic pressure, and at the check valve 112, which is located in the oil supply flow path 102, which is connected to the reservoir 30 in such a way that it is continuous with the outlet side of the device 100 for supplying hydraulic pressure, with reference to the Fig. 9 and Fig. 10 described.

[0097] Fig. Figure 9 is a circuit diagram of a hydraulic circuit representing a state of testing whether a leakage occurs in an electric braking system according to yet another embodiment of the present disclosure.

[0098] Referring to Fig. In section 9, the inspection valve 60 is provided in a flow path that connects the reservoir 30 to the device 100 for supplying hydraulic pressure to the brake system. The inspection valve 60 can be installed in the oil flow path 101 that connects the reservoir 30 to the hydraulic pressure chamber 110 of the device 100 for supplying hydraulic pressure in order to control the hydraulic pressure supplied between the reservoir 30 and the device 100 for supplying hydraulic pressure. The inspection valve 60 can be configured with a normally open solenoid valve that is open in the resting state and closes when a closing signal is received.

[0099] The test procedure through the electric brake system, including the inspection valve 60, can be performed when the vehicle is stationary. First, with the inspection valve 60 open, the first and second shut-off valves 261 and 262, located in the backup flow paths 251 and 252 connecting the master cylinder 20 to the hydraulic pressure control unit 200, are closed. This is to prevent hydraulic pressure from escaping from the device 100, which supplies hydraulic pressure to the master cylinder 20, via the first and second flow paths 251 and 252 through the inlet valves 221, 222, 223, and 224.

[0100] Next, the hydraulic pressure supply device 100 is actuated to pressurize the hydraulic piston 120, which is located inside the hydraulic pressure chamber 110. The second pressure sensor PS2 is used to check whether pressure is being generated. If hydraulic pressure is detected in the hydraulic pressure supply device 100, i.e., if pressure is being generated, it is determined that no leakage has occurred and the second test mode is terminated. If, on the other hand, no pressure is generated in the hydraulic pressure chamber 110, or if the pressure generated is lower than a specified value, it is determined that a leakage has occurred at the sealing element 113 or the check valve 112, and the subsequent test is performed.

[0101] If no pressure is built up, for example, the hydraulic piston 120 within the hydraulic pressure chamber 110 is returned to its original position. That is, the hydraulic piston 120 is returned to its original position via the motor 140 and the power conversion unit 130. Then, as in Fig.As shown in Figure 10, the inspection valve 60 and the shut-off valves 261 and 262 are closed, thus changing the hydraulic pressure chamber 110 of the device 100 for supplying hydraulic pressure to form a closed circuit. The reason for closing the inspection valve 60 and the shut-off valves 261 and 262 is that it is difficult to identify whether a leak occurs when the hydraulic pressure generated by the device 100 for supplying hydraulic pressure flows into the reservoir 30 via the inspection valve 60 or into the main cylinder 20 via the shut-off valves 261 and 262, resulting in a pressure loss.

[0102] In a state where the inspection valve 60 and the shut-off valves 261 and 262 are closed, the hydraulic piston 120, which is located in the hydraulic pressure chamber 110, is moved to release the hydraulic pressure, and whether pressure is built up is detected by the second pressure sensor PS2. That is, any leakage is detected by the second pressure sensor PS2 based on whether pressure is being built up.

[0103] For example, it is determined that a leakage occurs at the sealing element 113 if the second pressure sensor PS2 detects that pressure is being built up, whereas it is determined that a leakage occurs at the check valve 112 if the second pressure sensor PS2 does not detect that pressure is being built up. The reason for this is that hydraulic pressure is not built up if the hydraulic pressure escapes into the check valve 112 when the hydraulic pressure is built up again in a state where the pressure was not built up during an initial test, and the closed circuit between the reservoir 30 and the hydraulic pressure chamber 110 is provided by the inspection valve 60, even if the hydraulic pressure escapes via the sealing element 113, so that hydraulic pressure is built up, and it is determined that a leakage occurs at the sealing element 113.

[0104] As described above, the inspection valve 60 is provided, and whether a leak occurs in the electric brake system is checked via the opening and closing operations of the inspection valve 60, thus preventing a safety risk. The test mode can be controlled to be executed when a predetermined time has elapsed after the vehicle has stopped, when the handbrake is currently engaged, or when a driver applies a predetermined braking force to the vehicle. It is also possible in test mode to quickly release hydraulic pressure from the wheel cylinders 40 if it is determined that the driver intends to accelerate the vehicle.

[0105] The inspection valve 60 comprises an internal flow path that opens and closes according to the opening and closing operation, with one side connected to the reservoir 30 and the other side to the main cylinder 20 and the device 100 for supplying hydraulic pressure via a branch flow path. Therefore, the inspection valve 60 is controlled to open the flow path connecting the reservoir 30 to the main cylinder 20 and the reservoir to the device 100 for supplying hydraulic pressure in braking mode, and to close the flow path connecting the reservoir 30 to the main cylinder 20 or the reservoir 30 to the device 100 for supplying hydraulic pressure in testing mode.Here, an unspecified reference numeral is a check valve provided in the flow path connecting the reservoir 30 to the main cylinder 20 and the reservoir 30 to the device 100 for supplying hydraulic pressure, together with the test valve 60, to prevent hydraulic pressure from being supplied to the reservoir 30.

[0106] As is evident from the above description, the electric braking system and a leakage testing method according to an embodiment of the present disclosure actuate an inspection valve for modifying a master cylinder (20) to form a closed circuit, so that leaks of a simulation valve and a simulation check valve connected to the master cylinder and a rear end part of a simulation device can be tested, which has the effect of avoiding a safety risk due to a leakage of hydraulic pressure.

[0107] The inspection valve is also actuated to convert a hydraulic pressure chamber of the device for supplying hydraulic pressure into a closed circuit, so that it can be checked whether hydraulic pressure supplied by the device for supplying hydraulic pressure is escaping.

[0108] Additionally, only two of the four inlet valves are actuated, with each controlling a flow of hydraulic pressure supplied to wheel cylinders to apply pressure to all wheel cylinders, thereby minimizing actuation noise and vibration of the valves.

[0109] Furthermore, the motor and valves are interlocked and controlled, enabling precise pressure control. Additionally, two hydraulic circuits are designed to connect to two wheels and be controlled independently. A hydraulic pressure supply device is interlocked and controlled by these two hydraulic circuits according to the pressure required for each wheel and a priority logic, which offers the advantage of increasing the control range.

[0110] Furthermore, if a braking system fails, a driver's pedal force can be delivered directly to the master cylinder to enable braking of a vehicle, thus ensuring a stable braking force.

Claims

[1] A method for leak testing an electric brake system, comprising: a master cylinder (20) connected to an oil-storing reservoir (30) and configured to generate hydraulic pressure corresponding to a pedal force of a brake pedal (10); a simulation device (50) one side of which is connected to the master cylinder (20) to provide a reaction force corresponding to the pedal force of the brake pedal (10), and the other side of which is connected to the reservoir (30); a simulation valve (54) provided in a flow path connected to the master cylinder (20) or a flow path connected to the reservoir (30); a device (100) for supplying hydraulic pressure, actuated by an electrical signal from a pedal position sensor that detects a displacement of the brake pedal (10) and configured to generate hydraulic pressure; and a hydraulic pressure control unit (200) configured toto control the hydraulic pressure delivered by the main cylinder (20) and / or the device (10) for supplying hydraulic pressure, and to supply the hydraulic pressure to a wheel cylinder (40) provided on each wheel, comprising: Performing a test mode to test for leakage of the simulation valve (54) and a sealing element (23) provided within a chamber of the main cylinder (20) by providing an inspection valve (60) in the flow path connecting the main cylinder (20) to the container (30), wherein the test mode includes: (a1) Closing a shut-off valve (261, 262) provided on a flow path connecting the main cylinder (20) to the hydraulic pressure control unit (200) when the inspection valve (60) is open; (b1) Applying a vacuum to a piston located in the master cylinder (20) according to a pedal force of the brake pedal (10) and detecting whether pressure is built up via a pressure sensor (PS1); and (c1) Determine that no leakage exists if the pressure detected via the pressure sensor (PS1) meets a certain criterion. [2] Method according to claim 1, wherein if the pressure detected via the pressure sensor (PS1) in operation (c1) does not meet the predetermined criterion, it is determined that a leakage has occurred in the simulation valve (54) and / or the sealing element (23). [3] Method according to claim 1 or claim 2, further comprising: (d1) Returning the brake pedal (10) to its original position; (e1) Closing the inspection valve (60), the simulation valve (54) and the shut-off valve (261, 262) to reconfigure the chamber of the main cylinder (20) to form a closed circuit; (f1) Applying a vacuum to the piston located in the master cylinder (20) according to the pedal force of the brake pedal (10) and detecting whether pressure is built up via the pressure sensor (PS1); and (g1) Determine that a leak has occurred at the sealing element (23) if the pressure detected via the pressure sensor (PS1) meets the specified criterion, and determine that a leak has occurred at the simulation valve (54) if the pressure built up via the pressure sensor (PS1) does not meet the specified criterion. [4] A method for leak testing an electric brake system comprising: a master cylinder (20) connected to an oil storage reservoir (30) and configured to generate hydraulic pressure corresponding to a pedal force of a brake pedal (10); a simulation device (50) one side of which is connected to the master cylinder (20) to provide a reaction force corresponding to the pedal force of the brake pedal (10); a hydraulic pressure supply device (100) actuated by an electrical signal from a pedal travel sensor (11) sensing a displacement of the brake pedal (10) and configured to generate hydraulic pressure; and a hydraulic pressure control unit (200) configured to control the hydraulic pressure supplied by the master cylinder (20) and / or the hydraulic pressure supply device (100) and to supply the hydraulic pressure to a wheel cylinder provided at each wheel, comprising: Executing a test mode to test for leakage of a sealing element (113) provided within the chamber of the device (100) for supplying hydraulic pressure, and of a check valve (112) located in a flow path connected to a reservoir (30) at the outlet side of the device (100) for supplying hydraulic pressure, by providing an inspection valve (60) in a flow path connecting the reservoir (30) to an oil port of the device (100) for supplying hydraulic pressure. the test mode includes: (a2) Closing a shut-off valve (261, 262) provided in a flow path connecting the main cylinder (20) with the hydraulic pressure control unit (200) when the inspection valve (60) is open; (b2) Operating the device (100) to supply hydraulic pressure to operate a hydraulic piston (110) provided within the hydraulic pressure chamber (120) of the device (100) to supply hydraulic pressure, and detecting whether pressure is being built up via the pressure sensor (PS2); and (c2) determining that no leakage exists if the pressure detected via the pressure sensor (PS2) meets a certain criterion. [5] Method according to claim 4, wherein, if the pressure detected via the pressure sensor in operation (c2) does not meet the specified criterion, determining that a leakage has occurred in the sealing element (23) and / or the check valve (112). [6] Method according to claim 4 or claim 5, further comprising: (d2) Returning the hydraulic piston of the device (100) to its original position for supplying hydraulic pressure; (e2) Closing the inspection valve (60) and the shut-off valve (261, 262) to reconfigure the hydraulic pressure chamber of the device (100) to supply hydraulic pressure to form a closed circuit; (f2) Actuating the device (100) for supplying hydraulic pressure in order to pressurize the hydraulic piston (110) which is provided in the hydraulic pressure chamber (120) of the device (100) for supplying hydraulic pressure and detecting whether pressure is built up via the pressure sensor (PS2); and (g2) Determine that a leak has occurred at the sealing element (113) if the pressure detected via the pressure sensor (PS2) meets the specified criterion, and determine that a leak has occurred at the check valve (112) if the pressure detected via the pressure sensor (PS2) does not meet the specified criterion.

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