Electronic braking system

Abstract

Electronic braking system comprising a reservoir (30) in which oil is stored, a master cylinder (20) having a first oil pressure port (24a) and a second oil pressure port (24b) and coupled to the reservoir (30) to receive the oil, a pedal travel sensor (11) configured to detect a travel of a brake pedal (10) and a simulation device (50) connected to the master cylinder (20) and configured to provide a response corresponding to a pedal force of the brake pedal (10), wherein the electronic braking system comprises: a hydraulic pressure supply unit (100) which is designed to to output an electrical signal via the pedal travel sensor (11) to actuate a motor (140) when the brake pedal (10) is actuated, and is designed to convert rotational power of the motor (140) into linear motion; an oil pressure control unit (200) comprising a first oil pressure circuit (201) and a second oil pressure circuit (202) connected to the hydraulic pressure supply unit (100) via a main oil pressure path (210), each configured to control two wheels, such that hydraulic pressure is received using a force generated by the hydraulic pressure supply unit (100) to perform braking; and an electronic control unit which is designed to control the motor (140) and valves based on hydraulic pressure information and to control pedal travel information the oil pressure control unit (200) includes: a first inlet valve (221) and a second inlet valve (222), each arranged on upper flows of two wheel cylinders, to control the hydraulic pressure flowing into the two wheel cylinders, each installed on the two wheels provided in the first and second hydraulic circuit (201, 202); a third inlet valve (223) and a fourth inlet valve (224), each arranged on upper flows of two wheel cylinders to control the hydraulic pressure flowing into the two wheel cylinders, each installed on the two wheels provided in the first and second hydraulic circuits (201, 202); a first balancing valve (241) configured to connect or disconnect the two wheel cylinders to which the first inlet valve (221) and the second inlet valve (222) are connected; and a second balancing valve (242) configured to connect or disconnect the two wheel cylinders to which the third inlet valve (223) and the fourth inlet valve (224) are connected, wherein the hydraulic pressure output by the four wheel cylinders is controlled by a rotation in a direction opposite to a direction of rotation of the motor (140) of the hydraulic pressure supply unit (100) during braking, where, when the electronic brake system is operating normally and the hydraulic pressure from the wheel cylinders flows out in the opposite direction by rotating the motor (140) of the hydraulic supply unit (100), only one of the first inlet valve (221) and the second inlet valve (222) is open, and only one of the third inlet valve (223) and the fourth inlet valve (224) is open.

Description

BACKGROUND 1. Area

[0001] Exemplary embodiments of the present invention relate to an electronic braking system and more precisely to an electronic braking system that is able to provide a simplification of the design and more precise pressure control. 2. Description of the state of the art

[0002] German patent application DE 10 2013 002 378 A1 discloses an electric braking system for vehicles with a pressure supply device connected to a reservoir via a hydraulic passage for receiving the oil, wherein the brake supply device outputs a driver's intention to brake as an electrical signal through the pedal displacement sensor when the driver operates the brake pedal to operate a motor and convert a rotational force of the motor into a linear motion.Furthermore, the electric braking system comprises a hydraulic control unit, including a first circuit containing at least one first vehicle wheel and a second circuit containing at least one second vehicle wheel for receiving hydraulic pressure with a force generated by the pressure supply device in order to perform braking, a blocking valve for controlling the hydraulic pressure from the master cylinder to a wheel cylinder located in each vehicle wheel, a simulation device connected to the master cylinder to provide a reaction force response to the pedal force of the brake pedal, and an electronic control unit for controlling the motor and the valves based on pressure information and pedal displacement information.

[0003] Every vehicle requires braking capability and therefore a braking system, and recently various types of braking systems have been proposed to achieve stronger and more stable braking forces. Examples of braking systems include an anti-lock braking system (ABS), which prevents wheel slip during braking; a brake-assisted traction control system (BTCS), which prevents drive wheel slip when a sudden or rapid acceleration occurs in a vehicle; and an electronic stability control system (ESC), which, together with the ABS and BTSC, is designed to control the hydraulic pressure of a braking system so that a vehicle is kept under stable driving conditions, etc.

[0004] Such an electronic braking system comprises a number of solenoid valves for controlling brake oil pressure, which is transmitted to wheel cylinders (called hydraulic brakes or disc brakes) mounted on the wheels of a vehicle, a pair of low-pressure accumulators for temporarily storing oil flowing from the wheel cylinders, a motor and pump for forcibly pumping the oil stored in the low-pressure accumulators, a number of check valves to prevent backflow of oil, and an electronic control unit (ECU) for controlling the operation of the solenoid valves and the motor, all compactly integrated into an aluminum oil pressure block.In addition, a hydraulic pressure supply unit is provided and used, which receives an electrical signal from a pedal travel sensor to scan the travel of a brake pedal in response to the driver's intention to brake when a driver presses the brake pedal and delivers pressure to the wheel cylinders.

[0005] The electronic braking system, equipped with the aforementioned hydraulic pressure supply unit, is disclosed in European Patent No. EP 2 520 473 B1. According to the disclosure, a hydraulic pressure supply unit is configured to generate brake pressure by actuating a motor in response to pressure on the brake pedal. Here, the brake pressure is generated by converting the motor's rotational power into a linear motion to push a piston.

[0006] However, in the electronic braking system with the aforementioned design, the arrangement of the multiple solenoid valves intended to control the pressure transmitted to the wheel cylinders is complex, and additionally, the multiple solenoid valves are individually actuated to control a hydraulic pressure supplied to the wheel cylinder provided in each wheel, thereby increasing the vibration and noise due to the actuation of the solenoid valves.

[0007] Furthermore, since the configuration of the majority of solenoid valves and the flow paths for controlling the pressure according to different pressure methods becomes complex, and the weight and volume of the system are additionally increased because a motor, a pump and a low-pressure accumulator are also required, there is a compromise between simplifying assembly and efficient use of space, and vibration and noise due to the operation of the motor and pump are increased. DEMOLITION

[0008] Therefore, one aspect of the present invention is to provide an electronic braking system capable of performing braking in accordance with a driver's pedal force when a braking system is operating anomalously, as well as simplifying its construction by minimizing the number of valves for controlling an oil pressure flow and precisely controlling the pressure.

[0009] Additional aspects of the invention are partly explained in the following description and partly are obvious from the description or can be recognized by implementing the invention.

[0010] In accordance with one aspect of the present invention, an electronic braking system comprises a reservoir in which oil is stored, a master cylinder having a first oil pressure port and a second oil pressure port and coupled to the reservoir to receive the oil, a pedal travel sensor configured to detect the travel of a brake pedal, and a simulation device connected to the master cylinder and configured to provide a response corresponding to a pedal force of the brake pedal, wherein the electronic braking system comprises: a hydraulic pressure supply unit configured to output an electrical signal via the pedal travel sensor to actuate a motor when the brake pedal is actuated and configured to convert rotational power of the motor into linear motion, and an oil pressure control unit having a first oil pressure circuit and a second oil pressure circuit.which are connected to the hydraulic pressure supply unit via a main oil pressure path and each is configured to control two wheels, such that hydraulic pressure is received using a force generated by the hydraulic pressure supply unit to perform braking, and an electronic control unit configured to control the motor and valves based on hydraulic pressure information and pedal travel information, the oil pressure control unit comprising: a first inlet valve and a second inlet valve, each arranged on upper flows of two wheel cylinders to control the hydraulic pressure flowing into the two wheel cylinders, each installed on the two wheels provided in the first and second oil pressure circuits; a third inlet valve and a fourth inlet valve, each arranged on upper flows of two wheel cylinders to control the hydraulic pressure.the hydraulic pressure flowing into the two wheel cylinders, each installed on the two wheels provided in the first and second hydraulic circuits, a first compensating valve configured to connect or disconnect the two wheel cylinders to which the first inlet valve and the second inlet valve are connected, and a second compensating valve configured to connect or disconnect the two wheel cylinders to which the third inlet valve and the fourth inlet valve are connected, wherein the hydraulic pressure output by the four wheel cylinders is controlled by a rotation in a direction opposite to the direction of rotation of the motor of the hydraulic pressure supply unit during braking.

[0011] The inlet valves may be fitted with normally closed solenoid valves that actuate a valve to open when an opening signal is received in a state where the valve is normally closed.

[0012] If the hydraulic pressure from the wheel cylinders is discharged in the opposite direction by rotating the motor of the hydraulic pressure supply device, the first inlet valve and the second inlet valve can be open.

[0013] When the hydraulic pressure from the wheel cylinders is discharged by rotating the motor of the hydraulic pressure supply device in the opposite direction, only one of the first inlet valve and one of the second inlet valve, and only one of the third inlet valve and one of the fourth inlet valve, are open.

[0014] The first and second balancing valves can be equipped with normally open solenoid valves that actuate a valve to close when a closing signal is received from the electronic control unit in a state where the valve is open during normal times.

[0015] The electronic braking system may also include a first backup path configured to connect the first oil pressure port and the first compensating valve so that oil is supplied directly to the wheel cylinders when the electronic braking system malfunctions; a second backup path configured to connect the second oil pressure port and the second compensating valve; a first shut-off valve provided in the first backup path and configured to control the flow of oil; and a second shut-off valve provided in the second backup path and configured to control a flow of oil.

[0016] The first and second shut-off valves can be fitted with normally open solenoid valves that actuate a valve to close when a closing signal is received from the electronic control unit in a state where the valve is open during normal times.

[0017] The hydraulic pressure supply unit may include: a motor configured to generate rotary power through the electrical signal of the pedal travel sensor, a power converter configured to convert a rotary motion of the motor into a linear motion, an oil pressure piston connected to the power converter and configured to perform a linear motion, a pressure chamber provided to slide with the oil pressure piston and connected to the first and second oil pressure circuits via the main oil pressure path, and an oil pressure spring provided in the oil pressure chamber and configured to elastically mount the oil pressure piston, the oil pressure chamber being connected to the reservoir via an oil pressure path to receive the oil.

[0018] A check valve can be installed in the oil path to prevent a backflow of pressure from the pressure chamber and to retain the oil in the pressure chamber when the oil pressure piston returns. BRIEF DESCRIPTION OF THE DRAWING

[0019] While the present invention is described in detail below with reference to the accompanying drawing, since the drawing shows exemplary examples of the present invention, the spirit and scope of protection of the present invention shall not be limited to the following figures: Fig. Figure 1 is a representation of an oil pressure circuit showing an unbraked state of an electronic braking system according to an exemplary embodiment of the present invention; Fig. Figure 2 is a representation of an oil pressure circuit when a brake of an electronic braking system is operating normally, according to an exemplary embodiment of the present invention; Fig. Figure 3 is a representation of an oil pressure circuit when a brake of an electronic braking system is released normally, according to an exemplary embodiment of the present invention; Fig. Figure 4 is a representation of an oil pressure circuit for describing an anti-lock braking system (ABS) that is actuated by the electronic braking system according to an exemplary embodiment of the present invention; Fig. Figure 5 is a representation of an oil pressure circuit for describing an electronic braking system operating in a drain mode, according to an exemplary embodiment of the present invention; and Fig. Figure 6 is a representation of an oil pressure circuit when an electronic braking system operates anomalously, according to an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0020] Exemplary embodiments of the present invention are described in detail below with reference to the accompanying figures. These exemplary embodiments are provided to fully explain the spirit and scope of the present invention to those skilled in the art. Therefore, the present invention should not be interpreted as being limited to the exemplary embodiments described below, and it can be implemented in various other embodiments. Parts irrelevant to the description are omitted from the figures for clarity. The dimensions of the elements in the figures may be exaggerated for ease of understanding.

[0021] Fig. Figure 1 is a representation of an oil pressure circuit showing an unbraked state of an electronic braking system according to an exemplary embodiment of the present invention.

[0022] Referring to the figures, the electronic braking system comprises a master cylinder that generates hydraulic pressure, a reservoir 30 coupled to an upper part of the master cylinder 20 to store oil, an input rod 12 that compresses the master cylinder 20 according to a braking force of a brake pedal 10, a wheel cylinder 40 to which the hydraulic pressure is transferred to perform a braking action on each wheel RR, RL, FR and FL, a pedal travel sensor 11 that detects a travel of the brake pedal 10 and a simulation device 50 that provides a reaction against the braking force of the brake pedal 10.

[0023] Here, the master cylinder 20 is configured with at least one chamber for generating hydraulic pressure. As shown in the figures, a first piston 21a and a second piston 22a form two chambers, and the first piston 21a is in contact with the input rod 12. To ensure safety in the event of a failure, the master cylinder 20 has two chambers. For example, one of the two chambers is connected to a right front wheel FR and a left rear wheel RL of a vehicle, and the other chamber is connected to a left front wheel FL and a right rear wheel RR of the vehicle. Alternatively, one of the two chambers can be connected to the two front wheels FR and FL, and the other chamber can be connected to the two rear wheels RR and RL. The reason for forming two independent chambers, as described above, is to ensure that the vehicle remains braked even if one chamber fails.In the main cylinder 20, a first and a second oil pressure port 24a, 24b are formed to release hydraulic pressure from the two chambers.

[0024] Furthermore, a first spring 21b is arranged between the first piston 21a and the second piston 22a of the master cylinder 20, and a second spring 22b is provided between the ends of the second piston 22a and the master cylinder 20. That is, the first spring 21b and the second spring 22b are each provided for the two chambers to store an elastic force resulting from the compression of the first piston 21a and the second piston 22a. The elastic force pushes the first and second pistons 21a and 22a in such a way that they return to their original position when the force pushing the first piston 21a is less than the elastic force.

[0025] There is no gap between the master cylinder 20 and the input rod 12 because pressing the input rod 12 forces the first piston 21a of the master cylinder 20 against the second piston 22a, causing them to come into contact. That is, when the brake pedal 10 is pressed, the master cylinder 20 is directly actuated without any ineffective pedal travel.

[0026] The simulation device 50 for providing a response based on the pedal force of the brake pedal 10 is connected to a first backup path 251, which is described below. As shown in the figures, the simulation device 50 comprises a simulation chamber 51, which stores oil discharged from the first oil pressure port 24a of the master cylinder 20, a reaction piston 52 provided within the simulation chamber 51, a pedal simulator including a reaction spring 53 that elastically supports the reaction piston 52, and a simulation valve 54 connected to a rear end of the simulation chamber 51. The simulation chamber 51 is installed here to exhibit a displacement within a predetermined range, which is determined by the oil flowing into the simulation chamber 51 due to the reaction piston 52 and the reaction spring 53.

[0027] The simulation valve 54 is designed to connect the rear end of the simulation chamber 51 and the container 30. That is, the 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, thus filling the pedal simulator, i.e., the entire internal volume of the simulation chamber 51, with oil.

[0028] The simulation valve 54 is designed with a normally closed solenoid valve, which is in a closed state during normal times, and when a driver presses the brake pedal 10, the simulation valve 54 is open to transfer brake fluid to the simulation chamber 51.

[0029] Furthermore, a simulation check valve 55 is installed in parallel to the simulation valve 54. The simulation check valve 55 allows oil to flow from the reservoir 30 only into the simulation chamber 51. This means that the reaction piston 52 of the pedal simulator compresses the reaction spring 53, and oil within the simulation chamber 51 is transferred to the reservoir 30 via the simulation valve 54. Since the simulation chamber 51 is thus filled with oil when the simulation device 50 is operating, the friction of the reaction piston 52 is minimized, thereby improving the service life of the simulation device 50 and preventing the ingress of foreign material from the outside.

[0030] Furthermore, when the pedal force of the brake pedal is released, the supply of oil to the simulation chamber 51 via the simulation check valve 55 ensures that the pressure of the pedal simulator returns quickly.

[0031] The electronic braking system according to the embodiment of the present invention comprises a mechanically operated hydraulic pressure supply unit 100, which receives an electrical signal from the pedal travel sensor 11 to detect a movement of the brake pedal 10 when a driver presses a brake; an oil pressure control unit 200, which is configured with a first and a second oil pressure circuit 201 and 202, each assigned to two wheels, which control the flow of hydraulic pressure supplied to the wheel cylinder 40 provided at each wheel RR, RL, FR and FL; a first shut-off valve 261, which is provided in the first backup path 251 to connect the first oil pressure port 24a and the first oil pressure circuit 201 and which controls a flow of hydraulic pressure; and a second shut-off valve 262, which is provided in the second backup path 252 to connect the second oil pressure port 24b and the second oil pressure circuit 202.and which controls a flow of hydraulic pressure, and an electronic control unit (ECU) (not shown) that controls the hydraulic pressure supply unit 100 and valves 54, 221, 222, 223, 224, 241, 242, 261 and 262 based on the hydraulic pressure information and the pedal travel information.

[0032] The hydraulic pressure supply unit 100 comprises a pressure chamber 110, in which a predetermined space is provided for receiving and storing oil, a pressure piston 120 and an oil pressure spring 122 provided in the pressure chamber 110, a motor 140 that generates rotary power in response to the electrical signal from the pedal position sensor 11, and a power converter 130 that converts a rotary motion of the motor 140 into a linear motion to move the oil pressure piston 120 in a straight line. Here, the reservoir 30 and the pressure chamber 110 are connected by an oil passage 103 to supply the oil to the pressure chamber 110. Additionally, the signal detected by the pedal position sensor 11 is transmitted to the ECU, and the ECU controls the motor 140 and valves included in the electronic braking system according to the embodiment of the present invention described below.Operations for controlling a plurality of valves due to the displacement of the brake pedal 10 are described below.

[0033] As described above, the pressure chamber 110 is connected to the reservoir 30 via the oil path 103 and receives and stores the oil. As described above, the hydraulic piston 120 and the hydraulic spring 122, which elastically supports the hydraulic piston 120, are located in the pressure chamber 110. Here, the hydraulic pressure generated by the pressure of the hydraulic piston 120 is transmitted via a main hydraulic path 210 to the wheel cylinder 40, which is installed in each wheel RR, RL, FR, and FL.

[0034] The oil pressure piston 120, which compresses the pressure chamber 110, is connected to the power converter 130, which converts the rotational power of the motor 140 into a linear motion in the pressure chamber 110, and moves in a sliding manner.

[0035] The power converter 130 is a device that converts rotational power into linear motion and is designed, for example, with a ball screw nut arrangement. For instance, the power converter 130 can be configured with a screw integrally formed with a rotating shaft of the motor 140 (not shown) and a ball nut screwed to the screw with limited rotation, performing a linear motion corresponding to the screw's rotation. That is, the screw serves as the rotating shaft of the motor 140 and is responsible for the linear motion of the ball nut. Here, the hydraulic piston 120 is connected to the ball nut of the power converter 130 to compress the pressure chamber 110 through the linear motion of the ball nut, and the hydraulic spring 122 serves to return the hydraulic piston 120 to its original shape when the ball nut returns to its original position.

[0036] Although not shown, the power converter 130 can be configured with a ball nut that is rotatable by receiving rotational power from the rotating shaft of the motor 140, and a screw that is screw-coupled to the ball nut with limited rotation and performs a linear motion corresponding to the rotation of the ball nut. Such a ball nut screw arrangement is a published, well-known technique for a device that converts rotary motion into linear motion, and therefore a detailed description is omitted. Furthermore, the power converter 130, according to the embodiment of the present invention, should be understood to include, in addition to the ball nut screw arrangement, any configuration capable of converting rotary motion into linear motion.

[0037] Motor 140 is an electric motor that generates rotational power in response to a signal output by the ECU, producing power in either a normal or reverse direction depending on the ECU settings. Precise control is possible by adjusting the rotation angle or speed of Motor 140. This type of Motor 140 is a well-documented, publicly available technology; therefore, a detailed description is omitted.

[0038] Additionally, a check valve 120 is installed in the oil path 103 to prevent backflow of pressure from the pressure chamber 110. The check valve 102 serves to prevent backflow of pressure from the pressure chamber 110 and also to prevent suction, and it retains the oil in pressure chamber 110 when the oil pressure piston 120 is reset.

[0039] When an electronic braking system, including the aforementioned hydraulic pressure supply unit 100, is used, the electronic braking system can be configured to prevent situations in which the pressure in the pressure chamber 110 does not return to atmospheric pressure during the process of drawing oil into the pressure chamber 110 while the oil pressure piston 120 is reset. For example, a shut-off port 111 is formed in the pressure chamber 110, and a connecting passage 101, linking the shut-off port 111 and the oil passage 103, is formed between the pressure chamber 110 and the oil passage 103. Here, the shut-off port 111 is formed in a position corresponding to the initial position of the oil pressure piston 120. Thus, when the oil pressure piston 120 is reset, the oil pressure piston 120 is automatically connected to the container 30 via the connection path 110 and the pressure of the pressure chamber 110 returns to atmospheric pressure.

[0040] Meanwhile, a reference symbol 'PS1', which is not described, refers to a first pressure sensor that detects a hydraulic pressure of pressure chamber 110.

[0041] The hydraulic control unit is configured with the first hydraulic circuit 201 and the second hydraulic circuit 202, which receive hydraulic pressure to control two wheels each. As shown in the figures, the wheel controlled by the first hydraulic circuit 201 can be configured as the right front wheel FR and the left rear wheel RL, and the wheel controlled by the second hydraulic circuit 202 can be configured as 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 receives the hydraulic pressure to perform the braking action. This means that the oil pressure control unit 200 receives the hydraulic pressure from the hydraulic pressure supply unit 100 via the main oil pressure path 210, which is connected to the first and second oil pressure circuits 201 and 202, and each of the oil pressure circuits 201 and 202 includes a plurality of valves 221, 222, 223, 224, 241 and 242 to control a hydraulic pressure flow.

[0042] The first hydraulic pressure circuit 301 comprises a first and a second inlet valve 221 and 222, which are connected to the main hydraulic pressure path 210 to control the hydraulic pressure transmitted to the wheel cylinders 40, and a first balancing valve 241, which connects or disconnects two wheel cylinders 40, each connected to the first inlet valve 221 and the second inlet valve 222. Specifically, the first inlet valve 221 is provided in the first hydraulic pressure path 211, which connects the main hydraulic pressure path 210 and the right front wheel FR, and the second inlet valve 222 is provided in the second hydraulic pressure path 212, which connects the main hydraulic pressure path 210 and the left rear wheel RL. The first compensating valve 241 is provided in a path that connects the first oil pressure path 211 and the second oil pressure path 212 and serves to connect or disconnect the first and second oil pressure paths 211 and 212 according to an opening and closing operation of the same.

[0043] The second hydraulic circuit 201 comprises a third and a fourth inlet valve 223 and 224, which are connected to the main hydraulic circuit 210 to control hydraulic pressure transmitted to the wheel cylinders 40, and a second balancing valve 242, which connects or disconnects two wheel cylinders 40, each connected to the third inlet valve 223 and the fourth inlet valve 224, respectively. Specifically, the third inlet valve 223 is provided in the third hydraulic circuit 213, which connects the main hydraulic circuit 210 and the right rear wheel RR, and the fourth inlet valve 224 is provided in the fourth hydraulic circuit 214, which connects the main hydraulic circuit 210 and the left front wheel FL. The second compensating valve 242 is provided in the path that connects the third oil pressure path 213 and the fourth oil pressure path 214 and serves to connect or disconnect the third and fourth oil pressure paths 213 and 214 according to an opening or closing operation of the same.

[0044] The opening and closing operations of the first to fourth inlet valves 221, 222, 223, and 224 are controlled independently of the ECU and are performed to transmit the hydraulic pressure generated by the hydraulic pressure supply unit 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.

[0045] According to one embodiment of the present invention, the hydraulic pressure can be transmitted to each wheel cylinder 40 of the wheels FR, FL, RR and RL by opening two of the four inlet valves 221, 222, 223 and 224. As, for example, in Fig. As shown in Figure 2, the hydraulic pressure can be transmitted to each wheel cylinder 40 of wheels FR, FL, RR, and RL by opening the first inlet valve 221 of the first and second inlet valves 221 and 222, and by opening the fourth inlet valve 224 of the third and fourth inlet valves 223 and 224. That is, the hydraulic pressure passing through the first and fourth inlet valves 221 and 224 is transmitted to adjacent wheel cylinders 40 via the first and second balancing valves 241 and 242. Although here the hydraulic pressure to each wheel cylinder 40 is transmitted by opening inlet valves 221 and 224 respectively in the first oil pressure circuit 201 and the second oil pressure circuit 202, the present invention is not limited to this and the hydraulic pressure can be transmitted to each wheel cylinder 40 by opening two inlet valves 221 and 222, which are provided in the first oil pressure circuit 201 according to the design of the connecting paths.Furthermore, if there is a need for emergency braking, the hydraulic pressure can also be quickly transferred to each wheel cylinder 40 by opening all inlet valves 221, 222, 223 and 224.

[0046] The first through fourth intake valves 221, 222, 223, and 224 are equipped with normally closed solenoid valves that actuate a valve to open when an opening signal is received in a state where the valve is normally closed. Additionally, the first and second balancing valves 241 and 242 are equipped with normally open solenoid valves that actuate a valve to close when a closing signal is received from the ECU in a state where the valve is normally open.

[0047] According to one aspect of the present invention, the first and second backup paths 251 and 252 are provided to supply oil directly from the master cylinder 20 to each wheel cylinder 40 when the electronic brake system malfunctions. More precisely, the first shut-off valve 261 is provided in the first backup path 251 to control an oil flow, and the second shut-off valve 262 is provided in the second backup path 252 to control an oil flow. Furthermore, the first backup path 251 connects the first oil pressure port 24a to the first oil pressure circuit 201, and the second backup path 252 connects the second oil pressure port 25b to the second oil pressure circuit 202.As shown in the figure, the first backup path 251 is connected to the first balancing valve 241, which is connected to the first oil pressure path 211 and the second oil pressure path 212, and the second backup path 252 is connected to the second balancing valve 242, which is connected to the third oil pressure path 213 and the fourth oil pressure path 214. The operation of the first and second shut-off valves 261 and 262 is described below.

[0048] The first and second shut-off valves 261 and 262 are equipped with normally open solenoid valves, each of which actuates a valve to close when a closing signal is received from the ECU in a state where the valve is open at normal times.

[0049] Furthermore, a reference sign 'PS2', which is not described, refers to a second pressure sensor that measures the oil pressure of the main cylinder 20.

[0050] The operation of the electronic braking system is described in detail below according to an exemplary embodiment of the present invention.

[0051] Fig. Figure 2 is a representation of an oil pressure circuit when a brake of an electronic braking system is operating normally.

[0052] When referring to Fig. 2. When a driver begins to brake, the braking force requested by the driver can be detected using pressure information and the like via the pedal travel sensor 11, which responds to the brake pedal 10 pressed by the driver. The ECU (not shown) drives the motor 140 by receiving an electrical signal output by the pedal travel sensor 11. Furthermore, the ECU can detect the amount of regenerative braking via a second pressure sensor PS2, located at an outlet of the master cylinder 20, and via a first pressure sensor PS1, located in the main oil pressure line 210. It can then calculate the amount of friction braking based on the difference between the braking force requested by the driver and the amount of regenerative braking, thus determining the degree to which the wheel pressure increases or decreases.

[0053] When, in particular, a driver presses the brake pedal 10 in an initial braking state, the motor 140 is actuated, and the rotational power of the motor 140 is converted into linear motion by the power converter 130 to move the oil pressure piston 120 forward, generating hydraulic pressure by compressing the pressure chamber 110. Here, the first and second shut-off valves 261 and 262, installed in the first and second backup paths 251 and 252 respectively and connected to the first and second oil pressure ports 24a and 24b of the master cylinder 20, are closed, preventing the oil pressure generated by the master cylinder 20 from being transmitted to each wheel cylinder 40.

[0054] Furthermore, the hydraulic pressure generated by the pressure chamber 110 is transmitted to the wheel cylinders 40 of the right front wheel FR and the left front wheel FL by opening the first and fourth inlet valves 221 and 224, thus generating a braking force. At this point, the hydraulic pressure flowing through the first and fourth inlet valves 221 and 224 is transmitted 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 by the opening operations of the two inlet valves 221 and 224 selected from the four inlet valves 221, 222, 223, and 224.

[0055] This is the process that occurs in a typical braking situation, and if there is a need for emergency braking, the hydraulic pressure can also be quickly transferred to the wheel cylinders 40 by opening all inlet valves 221, 222, 223 and 224.

[0056] The pressure generated by the brake pedal force 10, which compresses the master cylinder 20, is then transmitted to the simulation device 50, which is connected to the master cylinder 20. The simulation valve 54, a normally closed type located at the rear end of the simulation chamber 51, is open, and the oil present in the simulation chamber 51 is supplied to the reservoir 30 via the simulation valve 54. Furthermore, the reaction piston 52 moves, and a pressure corresponding to the weight of the reaction spring 53, which supports the reaction piston 52, is generated in the simulation chamber 51, thus providing appropriate pedal sensitivity to the driver.

[0057] Next, a case of releasing the brake when the electronic braking system is functioning normally will be discussed, with reference to Fig. 3 described. If, as in Fig. As shown in Figure 3, when a pedal force is released on the brake pedal 10, rotational power is generated in a direction opposite to the forward direction, in which the motor 140 moves the oil pressure piston 120, and the oil pressure piston 120 is returned to its original position. Here, the first to fourth inlet valves 221, 222, 223, and 224 and the first and second balancing valves 241 and 242 are controlled by the same opening and closing operations during braking. That is, the second and third inlet valves 222 and 223 are in a closed state, and the first and fourth inlet valves 221 and 224 are open.Thus, the hydraulic pressure delivered from the wheel cylinders 40 of the first oil pressure circuit 201 is transferred to the pressure chamber 110 via the first balancing valve 241 and the first inlet valve 221, and the hydraulic pressure delivered from the wheel cylinders 40 of the second oil pressure circuit 202 is transferred to the pressure chamber 110 via the second balancing valve 242 and the fourth inlet valve 224.

[0058] In the simulation device 50, the oil within the simulation chamber 51 is transferred to the main cylinder 20 by means of the reaction piston 52, which is returned to its initial position by the reaction spring 53, and oil is refilled into the simulation chamber 51 via the simulation valve 54 and the simulation check valve 55, which are connected to the reservoir 30, thus ensuring that the pressure of the pedal simulator is quickly reset.

[0059] If, in the meantime, the oil pressure piston 120 moves due to the hydraulic pressure supply unit 100 in the electronic brake system described above, a flow of oil within the pressure chamber 110 is controlled via the oil path 103 and the connecting path 101, which are connected to the reservoir 30.

[0060] The electronic braking system according to an embodiment of the present invention can, in particular, control a control range by controlling the valves 221, 222, 223, 224, 241 and 242, which are provided in the oil pressure control circuit 200, according to the pressure required by the wheel cylinder 40, which is provided at wheels RR, RL, FR and FL of the two oil pressure circuits 201 and 202. For example, Fig. 4 represents the case in which braking is carried out only on the corresponding wheel cylinder during the activation of an anti-lock braking system (ABS) and represents the case of braking only on the front wheel.

[0061] Referring to Fig. 4. The motor 140 operates according to the pedal force of the brake pedal 10. The rotational power of the motor 140 is converted into linear motion, thus generating hydraulic pressure by moving the pressure piston 120 forward and compressing the pressure chamber 110. Here, the first and second shut-off valves 261 and 262 are closed, and the oil pressure generated by the master cylinder 20 is not transmitted to the wheel cylinder 40. Furthermore, the second and third inlet valves 222 and 223 and the first and second balancing valves 241 and 242 are closed. The hydraulic pressure generated by the pressure chamber 110 is therefore transmitted to the wheel cylinder 40 of the right wheel FR via the first inlet valve 221 and to the wheel cylinder 40 of the left front wheel FL via the fourth inlet valve 224. Thus, the hydraulic pressure is only transmitted to the front wheels FL and FR of wheels RL, RR, FL and FR.

[0062] Since, according to one aspect of the present invention, the actuations of the first to fourth inlet valves 221, 222, 223 and 224 and of the first and second balancing valves 241 and 242 are controlled independently, as described above, the hydraulic pressure can be transmitted only to the rear wheels RR and RL, or the hydraulic pressure can be transmitted to the wheel cylinders 40 of the left front wheel and the left rear wheel FL and RL, the right front wheel and the left rear wheel FR and RL, or whichever requires the oil pressure.

[0063] In the electronic braking system according to the present invention, the brake pressure supplied to the wheel cylinder 40 can also only be delivered by the corresponding wheel cylinder 40. Fig. Figure 5, for example, represents a case in which the electronic braking system operates in a dumping mode to release only the hydraulic pressure to the corresponding wheel cylinder 40 and represents dumping only for the rear wheels RR and RL.

[0064] Referring to Fig. 5. The motor 140 operates according to the pedal force of the brake pedal 10. The rotational power of the motor 140 is converted into linear motion, and thus hydraulic pressure is drawn into the pressure chamber 110 by moving the hydraulic piston 120 backwards. Here, the first and fourth inlet valves 221 and 224 and the first and second balancing valves 241 and 242 are closed. Thus, the hydraulic pressure transmitted to the wheel cylinders 40 of the right rear wheel RR and the left rear wheel RL is drawn into the pressure chamber 110 via the second and third hydraulic pressure paths 212 and 213 and the main hydraulic pressure path 210. Therefore, the hydraulic pressure is released only at the rear wheels RR and RL of wheels RL, RR, FL, and FR and transmitted to the pressure chamber 110.

[0065] Since, according to one aspect of the present invention, the operations of the first to fourth inlet valves 221, 222, 223 and 224 and of the first and second balancing valves 241 and 242 are controlled independently, the hydraulic pressure can be reduced or released only at the rear wheels RR and RL; or the pressure of the corresponding wheel cylinder 40 of the left front wheel and left rear wheel FL and FR, the right front wheel and left rear wheel FR and RL, or the like, can be reduced or released by moving the oil pressure piston 120 backwards. Here, the pressure of the corresponding wheel cylinder can be reduced based on priorities, if necessary.

[0066] Finally, a case of anomalous operation of the electronic braking system is described. Referring to Fig.6. If the electronic braking system malfunctions, each of the valves 54, 221, 222, 2223, 224, 241, 242, 261, and 262 is initially in a non-actuated braking state. Thus, when a driver presses the brake pedal 10, the input rod 12, which is connected to the brake pedal 10, moves to the left, and the first piston 21a, in contact with the input rod 12, simultaneously moves to the left. The second piston 22a is also moved to the left by the first piston 21a. Since there is no gap between the input rod 12 and the first piston 21a, braking can be performed quickly. This means that the hydraulic pressure generated by pressing the master cylinder 20 is transmitted to the wheel cylinders via the first and second backup paths 251 and 252, which are connected in a backup mode for braking in order to generate a braking force.Here, the first and second shut-off valves 261 and 262, installed in the first and second backup paths 251 and 252, and the first and second balancing valves 241 and 242, connected to the first and second backup paths 251 and 252, are configured with solenoid valves in the normally open state. The simulation valve 54 and the first to fourth inlet valves 221, 222, 223, and 224 are configured with normally closed solenoid valves, thus transmitting the hydraulic pressure directly to the wheel cylinder 40. Therefore, stable braking can be achieved and braking stability can be improved.

[0067] It is evident from the above description that the electronic braking system, according to embodiments of the present invention, can have the following effects.

[0068] Firstly, the electronic braking system offers the advantage of simplified design compared to conventional systems by minimizing the number of valves required to control the oil pressure flow. Therefore, the dimensions of the braking system, specifically the modulator block housing the valves, can be reduced, allowing the electronic braking system to be implemented at lower production costs.

[0069] Secondly, since pressure is applied to all wheel cylinders using only two inlet valves among the four inlet valves to control a flow of hydraulic pressure transmitted to each wheel cylinder, the operating noise and vibration of the valves can be minimized.

[0070] Thirdly, since the motor and valves are controlled in a linked manner, the electronic braking system can precisely control the pressure. Furthermore, the electronic braking system is designed with two hydraulic pressure circuits, each connected to two independently controlled wheels and linked to a hydraulic pressure supply unit. These circuits control the pressure according to the requirements of each wheel and a priority-based logic, thus improving controllability.

[0071] Fourthly, if the braking system fails, a driver's braking force is transferred directly to the master cylinder, so that braking of the vehicle is still possible and a stable braking force can be provided. Description of reference symbols 10 Brake pedal 11 Pedal travel sensor 20 Master cylinder 30 containers 40 wheel cylinders 50 simulation devices 54 Simulation valve 100 hydraulic pressure supply units 110 pressure chamber 120 oil pressure pistons 130 power converters 140 engine 200 Oil pressure control unit 201 first oil pressure circuit 202 second oil pressure circuit 210 Main oil pressure path 221 first inlet valve 222 second inlet valve 223 third inlet valve 224 fourth inlet valve 241 first balancing valve 242 second balancing valve 251 first backup path 252 second backup path 261 first shut-off valve 262 second shut-off valve

Claims

[1] An electronic brake system comprising a reservoir (30) in which oil is stored, a master cylinder (20) having a first oil pressure port (24a) and a second oil pressure port (24b) and coupled to the reservoir (30) to receive the oil, a pedal travel sensor (11) configured to detect a travel of a brake pedal (10), and a simulation device (50) connected to the master cylinder (20) and provided to provide a response corresponding to a pedal force of the brake pedal (10), the electronic brake system comprising: a hydraulic pressure supply unit (100) which is designed outputting an electrical signal via the pedal travel sensor (11) to actuate a motor (140) when the brake pedal (10) is actuated and being configured to convert a rotational power of the motor (140) into a linear motion; an oil pressure control unit (200) having a first oil pressure circuit (201) and a second oil pressure circuit (202) connected to the hydraulic pressure supply unit (100) via a main oil pressure path (210) and each configured to control two wheels so as to receive a hydraulic pressure using a force generated by the hydraulic pressure supply unit (100) to perform braking; and an electronic control unit configured to control the motor (140) and valves based on hydraulic pressure information and a pedal travel information, wherein the oil pressure control unit (200) comprises: a first inlet valve (221) and a second inlet valve (222) respectively arranged at upper streams of two wheel cylinders for controlling the hydraulic pressure flowing into the two wheel cylinders respectively installed at the two wheels provided in the first and second oil pressure circuits (201, 202); a third inlet valve (223) and a fourth inlet valve (224) respectively arranged at upper streams of two wheel cylinders for controlling the hydraulic pressure flowing into the two wheel cylinders respectively installed at the two wheels provided in the first and second oil pressure circuits (201, 202); a first compensating valve (241) configured to connect or disconnect the two wheel cylinders to which the first inlet valve (221) and the second inlet valve (222) are connected; and a second compensating valve (242) configured to connect or disconnect the two wheel cylinders to which the third inlet valve (223) and the fourth inlet valve (224) are connected, wherein the hydraulic pressure output from the four wheel cylinders is controlled by rotation in a direction opposite to a direction of rotation of the motor (140) of the hydraulic pressure supply unit (100) during braking, wherein, when the electronic brake system operates normally and the hydraulic pressure flows out from the wheel cylinders by rotating the motor (140) of the hydraulic supply unit (100) in the reverse direction, only one of the first inlet valve (221) and the second inlet valve (222) is open and only one of the third inlet valve (223) and the fourth inlet valve (224) is open. [2] An electronic brake system according to claim 1, wherein said inlet valves (221, 222, 223, 224) are provided with normally closed type solenoid valves which actuate a valve to open when an opening signal is received in a state where the respective valve is closed at normal times. [3] An electronic brake system according to claim 1, wherein when the hydraulic pressure flows out from the wheel cylinders by rotating the motor (140) of the hydraulic pressure supply unit (100) in the reverse direction, the first inlet valve (221) and the second inlet valve (222) are open. [4] An electronic brake system according to claim 3, wherein said first and second compensating valves (241, 242) are provided with normally open type solenoid valves which actuate a valve to close when a close signal is received from said electronic control unit in a state where said valve is open at normal times. [5] Electronic braking system according to claim 1, further comprising: a first backup path (251) configured to connect the first oil pressure inlet and the first relief valve (241) so that oil is directly supplied to the wheel cylinders when the electronic brake system operates abnormally; a second backup path (252) configured to connect the second oil pressure inlet and the second compensation valve (242); a first shut-off valve (261) provided in the first backup path (251) and configured to control the flow of oil; and a second shut-off valve (262) provided in the second backup path (252) and configured to control the flow of oil. [6] An electronic brake system according to claim 5, wherein said first and second cut-off valves (261, 262) are provided with normally open type solenoid valves which actuate a valve to close when a close signal is received from said electronic control unit in a state where said valve is open at normal times. [7] An electronic braking system according to claim 1, wherein the hydraulic pressure supply unit (100) includes: a motor (140) configured to generate rotational power by the electrical signal of the pedal travel sensor (11); a power converter (130) configured to convert a rotary motion of the motor (140) into a linear motion; an oil pressure piston (120) connected to the power converter (130) and configured to perform a rectilinear movement; a pressure chamber (110) slidably provided with the oil pressure piston (120) and connected to the first and second oil pressure circuits (201, 202) via the main oil pressure path (210); and an oil pressure spring (122) provided in the oil pressure chamber (110) and designed to elastically support the oil pressure piston (120), wherein the oil pressure chamber (110) is connected to the container (30) via an oil pressure path (103) to receive the oil. [8] An electronic brake system according to claim 7, wherein a check valve (102) is installed in the oil path (103) to prevent reverse pressure flow of the pressure chamber (110) and to store the oil in the pressure chamber (110) when the oil pressure piston (120) returns.

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