ELECTRIC HYDRAULIC BRAKE DEVICE

Abstract

Device for electro-hydraulic braking, comprising: a reservoir configured to store brake fluid; a backup brake cylinder (110) configured to respond to a brake pedal operation to change a pressure of the brake fluid in the backup brake cylinder (110); a motor (152) configured to generate rotational power based on a motor control signal; a master brake cylinder (120) with a main piston (122) which is designed to move together with the rotational power of the engine before and moves back and changes the pressure of the brake fluid in the master cylinder (120); a plurality of wheel brakes (w1, w2, w3, w4), each adapted to generate a braking force at each of the wheels; and an electronic control unit (ECU,140) configured to generate the engine control signal and a valve control signal so that the wheel brakes (w1,w2,w3,w4) generate a braking force based on a brake pedal operation; and a hydraulic circuit valve device having a backup valve (194, 195, 196, 197) configured to be operable based on the valve control signal to change a flow path of the fluid flowing within the hydraulic circuit valve device and to open and close a backup flow path (171, 172, 173, 174, 175, 176) between the backup brake cylinder (110) and the master brake cylinder (120), characterized by that the electronic control unit (140) reacts to the opening of the backup valve (194,195,196,197) when performing a hydraulic pressure reduction of the brake fluid in the hydraulic circuit valve device so that the brake fluid discharged from the master cylinder (120) is returned to the reservoir through a brake flow path (161,163).

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on and claims priority from Korean Patent Application No. 10-2020-0147299, filed on November 6, 2020, the disclosure of which is incorporated by reference in its entirety into this application. TECHNICAL FIELD

[0002] The present disclosure relates, in some embodiments, to an apparatus for electric-hydraulic braking. BACKGROUND

[0003] The statements in this section merely provide background information related to the present disclosure and are not necessarily part of the prior art.

[0004] A conventional electric hydraulic braking system adjusts the braking pressure of each wheel using a hydraulic modulator upon detecting the driver's pedal pressure through a sensor. The electric hydraulic braking system includes a sensor for detecting the pedal stroke to determine the driver's desired braking pressure, as well as a pedal simulator so the driver can feel the same pedal pressure as in a typical hydraulic braking system. The system further includes a control unit that determines the driver's required braking force through, for example, a pedal travel sensor and a pressure sensor, and drives a separate wheel braking mechanism to generate braking force at the wheel brakes. The wheel braking mechanism generally includes a master cylinder structure for generating hydraulic pressure and a hydraulic circuit, and valves for transmitting the hydraulic pressure generated by the master cylinder to the vehicle's wheel brakes.

[0005] However, the wheel brake mechanism has a plurality of solenoid valves to transmit the hydraulic pressure generated by the brake cylinder to the wheel brakes, and the more solenoid valves there are, the more complex the structure of the electric hydraulic brake system becomes. DE 10 2019 117 655 A1 discloses an electric-hydraulic brake with the features of the preamble of claim 1.

[0006] Despite their rare operational intervention, some solenoid valves must be included in the wheel brake mechanism for use in a specific mode, resulting in higher manufacturing costs and increased weight of the electric hydraulic brake system. OVERVIEW

[0007] According to at least one embodiment, the present disclosure provides an electro-hydraulic braking device comprising: a reservoir configured to store brake fluid; a backup brake cylinder; a motor; a master cylinder; a plurality of wheel brakes; an electronic control unit (ECU); and a hydraulic circuit valve device. The backup brake cylinder is configured to respond to a brake pedal operation to change the pressure of the brake fluid in the backup brake cylinder. The motor is configured to generate rotational power based on a motor control signal. The master cylinder includes a master piston configured to move back and forth along with the rotational power of the motor and change the pressure of the brake fluid in the master cylinder.The wheel brakes are each configured to generate a braking force at each of the wheels. The electronic control unit (ECU) is configured to generate the motor control signal and a valve control signal for the wheel brakes to generate a braking force based on a brake pedal operation. The hydraulic circuit valve device includes a backup valve configured to be operable based on the valve control signal to change a flow path of the fluid flowing within the hydraulic circuit valve device and to open and close a backup flow path between the backup brake cylinder and the master cylinder.In this case, the electronic control unit reacts to the opening of the backup valve when performing a hydraulic pressure reduction of the brake fluid in the hydraulic circuit valve device so that the brake fluid discharged from the master cylinder is returned to the reservoir through a brake flow path. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a block diagram illustrating a hydraulic circuit of an electric hydraulic brake according to at least one embodiment of the present disclosure. Fig. 2 shows a block diagram of the electric hydraulic brake according to at least one embodiment in a low-pressure reduction mode showing a flow of the brake fluid and opening / closing states of the solenoid valves. Fig. 3 is a block diagram of an electric hydraulic brake according to another embodiment in a low-pressure lowering mode, showing a flow of brake fluid and opening / closing states of solenoid valves. Fig. 4 shows a block diagram of the electric hydraulic brake according to at least one embodiment in a high-pressure lowering mode, showing a flow of the brake fluid and opening / closing states of the solenoid valves. Fig. 5 is a block diagram of the electric hydraulic brake according to another embodiment in a high pressure lowering mode, showing a flow of brake fluid and opening / closing states of the solenoid valves. Fig. 6 shows a block diagram of the electric hydraulic brake according to at least one embodiment having a second brake flow path in a fault condition, showing a flow of the brake fluid and opening / closing states of the solenoid valves. Fig. 7 is a block diagram of the electric hydraulic brake according to another embodiment having a second brake flow path in a failure state, showing a flow of the brake fluid and opening / closing states of the solenoid valves. REFERENCE SYMBOL 110 backup brake cylinders 120 master brake cylinder 140 Control unit 150 actuator 161, 163 Brake flow path 162, 164, 166 and 168 Return flow path 165b, 165a Main flow path 171, 172, 173, 174, 175, 176 Backup flow path 181, 182, 183, 184 intake valve 185, 186, 187, 188 exhaust valve 191, 192 traction control valve 193 Mixing valve 194, 195, 196, 197 backup valve w1, w2, w3, and w4 multiple wheel brakes DETAILED DESCRIPTION

[0008] Accordingly, the electric hydraulic brake device according to at least one embodiment of the present disclosure aims to eliminate solenoid valves that are used only in a specific mode and have a low operating frequency, and to use a backup valve and an exhaust valve to take over the capacity of the eliminated solenoid valves in their place to reduce the number of solenoid valves within the electric hydraulic brake device, thereby making the electric hydraulic brake device lighter.

[0009] Some embodiments of the present disclosure are described below with reference to the accompanying drawings. In the following description, like reference numerals preferably refer to like elements even though the elements are shown in different drawings. Furthermore, for the sake of clarity and conciseness, the following description of some embodiments omits a detailed description of known functions and configurations incorporated into the present application.

[0010] Alphanumeric codes such as first, second, i), ii), a), b), etc. in the description of components of the embodiments of the present disclosure are used merely to distinguish one component from another, but not to imply or suggest the substances, order, or sequence of components. Within this specification, when a part "comprises" or "includes" a component, it is meant that the part also includes and does not exclude other components, unless specifically described to the contrary.

[0011] Fig. 1 is a block diagram illustrating a hydraulic circuit of an electric hydraulic brake according to at least one embodiment of the present disclosure.

[0012] As in Fig. 1, the vehicle braking apparatus according to at least one embodiment of the present disclosure includes a backup brake cylinder 110, a master brake cylinder 120, wheel brakes w1, w2, w3 and w4, a control unit 140, an actuator 150 and a plurality of solenoid valves and flow paths.

[0013] The backup brake cylinder 110 includes a backup body 111, a first backup piston 112, a second backup piston 113, a backup stopper 114, a reaction damper 115, a first elastic member 116, and a second elastic member 117.

[0014] The backup body 111 is formed as a hollow structure. The first backup piston 112 and the second backup piston 113 are arranged inside the backup body 111 so that they can be moved linearly to the left and right. The interior of the backup body 111 is divided into a first backup chamber 118, which corresponds to the space between the first backup piston 112 and the second backup piston 113, and a second backup chamber 119, which corresponds to the space between the second backup piston 113 and the backup stopper 114.

[0015] The left and right ends of the backup body 111 are open. The left end of the first backup piston 112 is inserted into the open right end of the backup body 111, thereby closing the open right end of the backup body 111. The right end of the first backup piston 112 protrudes from the right end of the backup body 111, and the brake pedal 101 is connected to the protruding right end of the first backup piston 112. A stroke sensor 102 may be installed on the brake pedal 101 to detect a stroke of the brake pedal 101 when the driver depresses the brake pedal 101. The first backup piston 112 is installed to be linearly movable left and right while in close contact with the inner wall of the backup body 111.

[0016] The right end of the backup stopper 114 is inserted into the open left end of the backup body 111, thereby closing the open left end of the backup body 111.

[0017] The second backup piston 113 is installed within the backup body 111 so as to be linearly movable left and right while being in close contact with the inner wall of the backup body 111. The second backup piston 113 is arranged so as to be spaced apart from the first backup piston 112 and the backup stopper 114. The first elastic member 116 is arranged between the first backup piston 112 and the second backup piston 113, which are spaced apart from each other. The first elastic member 116 is composed of a spring member, one end of which elastically supports the first backup piston 112 and the other end of which elastically supports the second backup piston 113. The second elastic member 117 is arranged between the second backup piston 113 and the backup stopper 114, which are spaced apart from each other.The second elastic member 117 consists of a spring member, one end of which elastically supports the second backup piston 113 and the other end of which elastically supports the backup stopper 114.

[0018] The second backup piston 113 is formed as a hollow structure having a blind right side toward the first backup piston 112 and an open left side toward the backup stopper 114.

[0019] The backup stopper 114 penetrates the second elastic member 117 with its right end inserted and seated in the open left end of the second backup piston 113.

[0020] The reaction damper 115 is disposed inside the second backup piston 113 and has one end supported by the right end of the backup stopper 114 and the other end supported by the right side of the second backup piston 113. The reaction damper 115 is compressed when the second backup piston 113 is moved to the left, so that the driver feels a reaction due to the operation of the brake pedal 101. In this embodiment, the reaction damper 115 is formed of rubber so that the driver can feel the reaction force due to the operation of the brake pedal 101 through the elastic restoring force of the rubber.

[0021] The brake master cylinder 120 is driven by a motor 152, which is controlled by the control unit 140, to generate hydraulic pressure and supply it to the wheel brakes w1, w2, w3, and w4. Here, the control unit 140 may be an electronic control unit (ECU), which is a typical vehicle control device. When the driver depresses the brake pedal 101, the stroke sensor 102 detects the stroke of the brake pedal 101 and transmits it to the control unit 140, which then controls the motor 152 based on the stroke of the brake pedal 101 detected by the stroke sensor 102, thereby controlling the hydraulic pressure generated by the brake master cylinder 120. Here, the motor 152 is a drive motor that supplies power to the master piston 122 to advance it and generate hydraulic pressure for the brake master cylinder 120.

[0022] The brake master cylinder 120 has a main body 121, a main piston 122, a rod 123 and a main stopper 124.

[0023] The main body 121 is formed as a hollow structure. The main piston 122 is arranged within the interior of the main body 121 so that it can be moved linearly to the left and right. The interior of the main body 121 is divided by the main piston 122 into two parts, consisting of the first main chamber 125, which is located on the right side relative to the main piston 122, and the second main chamber 126, which is a space located on the left side of the main piston 122.

[0024] In this specification, the terms "left" and "right" are used only to indicate directions in which certain elements are shown in the drawings, and the present disclosure is not limited to their arrangement directions and positions.

[0025] The main piston 122, moving forward to the right, expands the second main chamber 126 and constricts the first main chamber 125. Conversely, the main piston 122, moving backward to the left, constricts the second main chamber 126 and expands the first main chamber 125.

[0026] The main body 121 is open at its left end and its right end. In the main body 121, the right end is fully open and the left end is partially open. A rod 123 is provided, which is inserted with its right end into the open left end of the main body 121. The right end of the rod 123 is connected to the main piston 122 within the main body 121. The rod 123 may be formed integrally with the main piston 122.

[0027] The main piston 122 and the rod 123 are formed to have different diameters, so that the main piston 122 has a larger diameter than the rod 123, which is thinner.

[0028] The left end of the rod 123 protrudes to the left from the main body 121, and the protruding left end of the rod 123 is equipped with an actuator 150 for linearly moving the rod 123 to the left and right.

[0029] The actuator 150 includes a motor 152 and an internally threaded screw and an externally threaded screw for converting the torque of the motor 152 into linear motion to move the rod 123 left and right in a straight line. The internally threaded screw has an inner peripheral surface formed with a helix. The internally threaded screw is further coupled to the left end of the rod 123. The externally threaded screw has an outer peripheral surface formed with a helix, which engages with the helix of the internally threaded screw and is inserted into the internally threaded screw. The externally threaded screw is connected to the rotor shaft of the motor 152 and rotates together with the rotor shaft of the motor 152 when rotated, thereby moving the internally threaded screw linearly along the rod 123 and, accordingly, moving the main piston 122 straight to the left or right.

[0030] The left end of the main stopper 124 is inserted into the open right end of the main body 121 to close the open right end of the main body 121.

[0031] Inside the main body 121, the main piston 122 is installed so that it can move linearly left and right while being in close contact with the inner walls of the main body 121. The outer peripheral surface of the main piston 122 is arranged to be in close contact with the inner walls of the main body 121 at the center and spaced distally therefrom. The main piston 122 has a hollow center, and the rod 123 has a hollow center. The externally threaded screw penetrates the internally threaded screw, and its right end is disposed in the rod 123. The main stopper 124 penetrates the main piston 122, and its left end is inserted and seated in the rod 123.

[0032] The second main chamber 126 houses the master piston 122 and the rod 123, but the first main chamber 125 houses only the master piston 122, not the rod 123. Therefore, when the master piston advances to the right, the effective cross-sectional area of the first main chamber 125, which compresses the brake fluid therein, is larger than the effective cross-sectional area of the second main chamber 126, which compresses the brake fluid therein when the master piston 122 moves backward to the left.

[0033] The control unit 140 generates a motor control signal for controlling the motor 152 so that the master cylinder 120 can generate hydraulic pressure, and generates a valve control signal for a hydraulic circuit valve device to open or close a plurality of solenoid valves therein. In the detailed description of the present disclosure, the hydraulic circuit valve device is referred to as a plurality of solenoid valves arranged in Fig. 1 are shown.

[0034] The wheel brakes w1, w2, w3 and w4 have a first wheel brake (w1) for braking the front left vehicle wheel, a second wheel brake w2 for braking the rear right vehicle wheel, a third wheel brake w3 for braking the rear left vehicle wheel and a fourth wheel brake w4 for braking the front right vehicle wheel.

[0035] The following relationships exist between the backup brake cylinder 110, the master brake cylinder 120 and the wheel brakes w1, w2, w3 and w4, which are designed as described above.

[0036] The first wheel brake w1 and the second wheel brake w2 are connected to a first brake flow path 161. Specifically, the first brake flow path 161 is branched such that one end thereof is connected to the first wheel brake w1 and the other end thereof is connected to the second wheel brake w2.

[0037] The first brake flow path 161 is equipped with a first inlet valve 181 and a second inlet valve 182 for opening and closing the first brake flow path 161. The first inlet valve 181 is arranged adjacent to the first wheel brake w1, and the second inlet valve 182 is arranged adjacent to the second wheel brake w2.

[0038] The first inlet valve 181 is provided with a check valve 181a to prevent backflow of the brake fluid, and the second inlet valve 182 is also provided with a check valve 182a to prevent backflow of the brake fluid.

[0039] The first brake flow path 161 is provided with a first pressure sensor 103 that measures the pressure of the brake fluid in the first brake flow path 161. Specifically, the first pressure sensor 103 is installed in the first brake flow path 161, which extends between the first inlet valve 181 and the second inlet valve 182.

[0040] A first return flow path 162 is connected at its branched one end to the first brake flow path 161, which extends between the first wheel brake w1 and the first inlet valve 181. Accordingly, the branched other end of the first return flow path 162 is connected to the first brake flow path 161, which extends between the second wheel brake w2 and the second inlet valve 182.

[0041] The first return flow path 162 is equipped with a first outlet valve 185 and a second outlet valve 186 for opening and closing the first return flow path. The first outlet valve 185 is disposed adjacent to one end of the first return flow path 162, and the second outlet valve 186 is disposed adjacent to the other end of the first return flow path 162.

[0042] The third wheel brake w3 and the fourth wheel brake w4 are connected to a second brake flow path 163. Specifically, the second brake flow path 163 is branched such that one end thereof is connected to the third wheel brake w3 and the other end thereof is connected to the fourth wheel brake w4.

[0043] The second brake flow path 163 is equipped with a third inlet valve 183 and a fourth inlet valve 184 for opening and closing the second brake flow path 163. The third inlet valve 183 is arranged adjacent to the third wheel brake w3, and the fourth inlet valve 184 is arranged adjacent to the fourth wheel brake w4.

[0044] The third inlet valve 183 is provided with a check valve 183a to prevent backflow of the brake fluid, and the fourth inlet valve 184 is also provided with a check valve 184a to prevent backflow of the brake fluid.

[0045] The second brake flow path 163 is provided with a second pressure sensor 104 that measures the pressure of the brake fluid in the second brake flow path 163. Specifically, the second pressure sensor 104 is installed in the second brake flow path 163, which extends between the third inlet valve 183 and the fourth inlet valve 184.

[0046] A second return flow path 164 is connected at its branched one end to the second brake flow path 163, which extends between the third wheel brake w3 and the third inlet valve 183. Furthermore, the branched other end of the second return flow path 164 is connected to the second brake flow path 163, which extends between the fourth wheel brake w4 and the fourth inlet valve 184. The second return flow path 164 is provided with a third exhaust valve 187 and a fourth exhaust valve 188 for opening and closing the second return flow path 164. The third exhaust valve 187 is disposed adjacent to one end of the second return flow path 164, and the fourth exhaust valve 188 is disposed adjacent to the other end of the second return flow path 164.

[0047] A second main flow path 165b is connected to the second main chamber 126 of the master cylinder 120 at one end. Specifically, the second main flow path 165b has one end connected to the main body 121 to be in fluid communication with the second main chamber 126 of the master cylinder 120. The other end of the second main flow path 165b is connected to the first inlet valve 181 and the second inlet valve 182 of the first brake flow path 161 via a first traction control valve 191.

[0048] The second main flow path 165b is equipped with a first traction control valve 191 for opening and closing the second main flow path 165b. The first traction control valve 191 is a solenoid valve controlled by the control unit 140 to open and close the second main flow path 165b. The first traction control valve 191 may be installed in the flow path to supply hydraulic pressure from the second main chamber 126 to the wheel brakes w1, w2, w3, and w4. The first traction control valve 191 is equipped with a check valve 191a. The check valve 191a is opened when the hydraulic pressure in the second main chamber 126 is higher than a certain pressure to bypass the hydraulic pressure in the second main chamber 126 supplied to the wheel brakes w1, w2, w3 and w4 while closing the first traction control valve 191.

[0049] A first main flow path 165a is connected to the first main chamber 125 of the master cylinder 120 at one end. Specifically, the first main flow path 165a has one end connected to the main body 121 to be in fluid communication with the first main chamber 125 of the master cylinder 120. The other end of the first main flow path 165a is connected to the third inlet valve 183 and the fourth inlet valve 184 of the second brake flow path 163 via a second traction control valve 192.

[0050] The first main flow path 165a is equipped with a second traction control valve 192 for opening and closing the first main flow path 165a. The second traction control valve 192 is a solenoid valve controlled by the control unit 140 to open and close the first main flow path 165a. The second traction control valve 192 may be installed in the flow path to supply hydraulic pressure from the first main chamber 125 to the wheel brakes w1, w2, w3, and w4. The second traction control valve 192 is equipped with a check valve 192a. The check valve 192a is opened when the hydraulic pressure in the first main chamber 125 is higher than a certain pressure to cause the hydraulic pressure in the first main chamber 125 to be bypassed to the wheel brakes w1, w2, w3 and w4 while the second traction control valve 192 is closed.

[0051] In the second main flow path 165b, a mixed flow path 169 is connected at one end to a node between the first traction control valve 191 and the first brake flow path 161. Furthermore, in the main flow path 165a, the other end of the mixed flow path 169 is connected to a node between the second traction control valve 192 and the second brake flow path 163. The mixed flow path 169 is provided with a mixing valve 193 that opens and closes the mixed flow path 169.

[0052] The first backup chamber 118 of the backup brake cylinder 110 is connected to one end of the first backup flow path 171, one end of which is connected to the second backup chamber 119. The first backup flow path 171 is connected at one end to the backup body 111 of the backup brake cylinder 110 to be in fluid communication with the first backup chamber 118, and is connected at the other end to the backup body 111 to be in fluid communication with the second backup chamber 119. A reservoir for storing brake fluid is installed in the first backup flow path 171.

[0053] One end of a third return flow path 166 is connected to the reservoir. The other end of the third return flow path 166 is connected to the first return flow path 162, which extends between the first outlet valve 185 and the second outlet valve 186.

[0054] In addition, one end of a fourth return flow path 168 is connected to the reservoir. The other end of the fourth return flow path 168 is connected to the second return flow path 164, which extends between the third outlet valve 187 and the fourth outlet valve 188.

[0055] The backup brake cylinder 110 is further connected to the reservoir via a second backup flow path 172.

[0056] The second backup flow path 172 is connected at one end to the second backup chamber 119. Namely, the second backup flow passage 172 is connected at one end to the second backup chamber 119 and at the other end to the first backup passage 171 extending between the reservoir in the backup body 111.

[0057] A first backup valve 194 is installed in the second backup flow path 172 to open and close it.

[0058] A third backup flow path 173 is provided with one end connected to the reservoir and the other end connected to the second main flow path 165b. The third backup flow path 173 is equipped with a check valve 105 to prevent the backflow of brake fluid.

[0059] A fourth backup flow path 174 is provided with a check valve 106 installed therein to prevent the backflow of the brake fluid.

[0060] The fourth backup passage 174 is connected at one end to the fourth return flow path 168 and at the other end to the first main chamber 125 of the master brake cylinder 120 via the check valve 106.

[0061] Further connected to the first backup chamber 118 is one end of a fifth backup flow path 175. Specifically, the fifth backup flow path 175 is connected at one end to the backup body 111 to be in fluid communication with the first backup chamber 118. The fifth backup flow path 175 is further connected at the other end to the main body 121 of the master cylinder 120. A third backup valve 196 is installed in the fifth backup flow path 175 to open and close the same. A third pressure sensor 107 is further installed in the fifth backup flow path 175 to measure the pressure of the brake fluid therein. In other words, the third pressure sensor 107 is installed in the fifth backup flow path 175 extending between the backup body 111 of the backup brake cylinder 110 and the third backup valve 196.

[0062] Further, one end of a sixth backup flow path 176 is connected to the second backup chamber 119 of the backup brake cylinder 110. The sixth backup flow path 176 is connected at one end to the backup body 111 to be in fluid communication with the second backup chamber 119. The sixth backup flow path 176 is further connected at the other end to the second main flow path 165b located between one end thereof and the other end of the third backup flow path 173. A second backup valve 195 is installed in the sixth backup flow path 176 to open and close the sixth backup flow path 176.

[0063] The above-mentioned components, including the first intake valve 181 to the fourth intake valve 184, the first exhaust valve 185 to the fourth exhaust valve 188, the first traction control valve 191, the second traction control valve 192, the mixing valve 193, the first backup valve 194, and the second backup valve 195, are composed of solenoid valves controlled by the control device 140.

[0064] The first intake valve 181, the second intake valve 182, the third intake valve 183, and the fourth intake valve 184 are of a normally open type because they are normally open when no control signal is input from the control unit 140.

[0065] On the other hand, the first exhaust valve 185, the second exhaust valve 186, the third exhaust valve 187 and the fourth exhaust valve 188 are formed as a normally closed type because they are normally closed when no control signal is input from the control unit 140.

[0066] The first traction control valve 191 and the second traction control valve 192 are configured as a normally open type when no control signal is input from the control unit 140. Furthermore, the mixing valve 193 is configured as a normally closed type when no control signal is input from the control unit 140.

[0067] The first backup valve 194 is configured as a normally closed type when no control signal is input from the control unit 140. The second backup valve 195 and the third backup valve 196 are further configured as a normally open type when no control signal is input from the control unit 140.

[0068] When the vehicle's brakes are controlled by the control unit 140, the control unit 140 closes the fourth backup valve 197, the third backup valve 196, and the second backup valve 195. Since the first, second, third, and fourth backup valves 194, 195, 196, and 197 are closed, the flow path between the backup brake cylinder 110 and the master cylinder 120 is subsequently blocked. Accordingly, in this case, the wheel brakes w1, w2, w3, and w4 generate braking force exclusively through the hydraulic pressure supplied from the master cylinder 120.

[0069] Incidentally, when no electric power is supplied to the control unit 140, the first backup valve 194, which is of the normally closed type, maintains a closed state, and the second backup valve 195 and the third backup valve 196, which are of the normally open type, remain open.

[0070] Therefore, in the non-power mode in which no power is supplied to the control unit 140 when the driver depresses the brake pedal 101, the hydraulic pressure formed in the second backup chamber 119 by receiving the brake fluid from the reservoir is supplied to the first main chamber 125 via the backup flow path 176.

[0071] Therefore, in the non-power mode in which no power is supplied to the controller 140, when the driver depresses the brake pedal 101, the hydraulic pressure formed in the first backup chamber 118 by receiving the brake fluid from the reservoir is transmitted to the node in the mixing flow path 169 between the mixing valve 193 and the second traction control valve 192 by way of the backup flow path 175, and this hydraulic pressure is then transmitted to the second brake flow path 163, thereby forming a braking force in the third brake w3 and the fourth brake w4.

[0072] In addition, the hydraulic pressure formed in the second backup chamber 119 by receiving the brake fluid from the reservoir is transmitted to the second main flow path 165b by means of the sixth backup flow path 176, and such hydraulic pressure is then transmitted to the subsequent first brake flow path 161, thereby forming a braking force in the first brake w1 and the second brake w2.

[0073] Thus, in the braking device of a vehicle according to at least one embodiment of the present disclosure, when the motor 152 is turned off because the control unit 140 is not supplied with power, the backup brake cylinder 110 can start to supply the master cylinder 120 with brake fluid so that the master cylinder 120 can generate sufficient hydraulic pressure to brake the plurality of wheel brakes w1, w2, w3 and w4 even when the motor 152 is not operating.

[0074] Fig. 2 shows a block diagram of the electric hydraulic brake according to at least one embodiment in a low-pressure reduction mode showing a flow of the brake fluid and opening / closing states of the solenoid valves.

[0075] Fig. 3 is a block diagram of an electric hydraulic brake according to another embodiment in a low-pressure lowering mode, showing a flow of brake fluid and opening / closing states of solenoid valves.

[0076] In the Fig. 2 and Fig. 3, dashed squares on the solenoid valves represent those that are actuated by receiving power from the control unit 140. Whereas, the solenoid valves without a dashed square represent those that are not actuated during a first-stage pressure relief operation.

[0077] In the detailed description of the present disclosure, the low-pressure reduction mode (or referred to as the “first-stage pressure release operation”) means an operation in which the motor 152 rotates so that the master piston 122 moves backward (on the left side in the corresponding drawing) and the brake fluid in the first brake flow path 161 and the second brake flow path 163 is returned to the first main chamber 125 via the first main flow path 165a.

[0078] In contrast, the low-pressure boost mode (also called the "first-stage boost operation") represents an operation in which the motor 152 rotates so that the master piston 122 advances (on the right side of the corresponding drawing) and the brake fluid in the first master chamber 125 is discharged to the first brake flow path 161 and the second brake flow path 163 via the first main flow path 165a.

[0079] The fourth backup flow path 174 according to at least one embodiment of the present disclosure Fig. 2 is connected at one end to the fourth return flow path 168 and at the other end via the check valve 106 to the first main chamber 125 of the master brake cylinder 120.

[0080] In contrast, the fourth backup flow path 174 according to another embodiment of the present disclosure is Fig. 3 is connected at one end to the fourth return flow path 168 and at the other end to the first main chamber 125 of the master cylinder 120 via the check valve 106 or a fourth backup valve 197. The fourth backup valve 197 is installed in the fourth backup flow path 174 to open and close the fourth backup flow path 174. Accordingly, the fourth backup valve 197 is configured as a normally closed type valve. Therefore, in the non-power mode, when no valve control signal is applied to the fourth backup valve 197, the fourth backup valve 197 closes the fourth backup flow path 174 to block the flow path of the brake fluid between the first main chamber 125 and the fourth return flow path 168.

[0081] During the first-stage pressure release operation, no current is applied to the fourth backup valve 197, which is a normally closed valve, so that the brake fluid in the second brake flow path 163 does not pass through the fourth backup flow path 174. Accordingly, the embodiment that does not include the fourth backup valve 197 has the same flow of brake fluid in the first-stage pressure release operation as that of another embodiment of the present disclosure that includes the fourth backup valve 197.

[0082] Likewise, in the first-stage boost operation, no current is applied to the fourth backup valve 197, which is a normally closed valve, so that the brake fluid within the second brake flow path 163 does not pass through the fourth backup flow path 174. Likewise, the embodiment that does not include the fourth backup valve 197 has the same flow of brake fluid in the first-stage boost operation as that of another embodiment of the present disclosure that includes the fourth backup valve 197.

[0083] Fig. 4 shows a block diagram of the electric hydraulic brake according to at least one embodiment in a high-pressure lowering mode, showing a flow of the brake fluid and opening / closing states of the solenoid valves.

[0084] Fig. 5 is a block diagram of the electric hydraulic brake according to another embodiment in a high pressure lowering mode, showing a flow of brake fluid and opening / closing states of the solenoid valves.

[0085] As in the Fig. 4 and Fig. 5, dashed squares on the solenoid valves represent those that are actuated by receiving power from the control unit 140. Whereas, the solenoid valves without a dashed square represent those that are not actuated during a second-stage pressure relief operation.

[0086] In the detailed description of the present disclosure, the high-pressure lowering mode (or referred to as the “second-stage pressure relief operation”) refers to an operation in which the motor 152 rotates so that the master piston 122 advances (on the right side of the respective drawings) and the brake fluid in the first brake flow path 161 and the second brake flow path 163 is returned to the second master chamber 126 via the second master flow path 165b.

[0087] On the other hand, the high-pressure boost mode (or referred to as the “second-stage boost operation”) refers to an operation in which the motor 152 rotates so that the master piston 122 moves backward (on the left side of the respective drawings) and the brake fluid in the second master chamber 126 is discharged to the first brake flow path 161 and the second brake flow path 163 via the second main flow path 165b.

[0088] In contrast to the first-stage pressure relief process, during the second-stage pressure relief process, the fourth backup valve 197 is opened by receiving power from the control unit 140. When the fourth backup valve 197 is open, the brake fluid in the first main chamber 125 of the master cylinder 120 is returned to the reservoir via the fourth return flow path 174. During the second-stage pressure relief process, if the fourth backup valve 197 is closed when the master piston 122 advances, the brake fluid in the first main chamber 125 is returned to the second brake flow path 163 via the first main flow path 165a, preventing the hydraulic pressure in the hydraulic circuit from dropping. Therefore, during the second pressure relief process, the fourth backup valve 197 must be open.

[0089] However, the electric hydraulic brake according to at least one embodiment of the present invention, which does not include a fourth backup valve 197, lowers the hydraulic pressure within the hydraulic circuit by means of the second backup valve 195 in the second stage pressure relief process.

[0090] The second backup valve 195 according to another embodiment of the present disclosure is configured as a normally open valve and is closed in the second stage pressure relief operation by receiving power from the control unit 140.

[0091] In contrast, according to at least one embodiment of the present disclosure, the second backup valve 195 repeatedly opens and closes during the second-stage pressure relief process, thereby allowing a portion of the brake fluid flowing from the second main flow path 165b in the second main chamber 126 to escape into the sixth backup flow path 176, so that the escaped brake fluid is returned to the reservoir. Therefore, in at least one embodiment of the present disclosure, even without the fourth backup valve 197, the second backup valve 195 can be used to recover the brake fluid drained from the first main chamber 125.

[0092] Accordingly, at least one embodiment of the present disclosure has the effect of reducing the manufacturing cost of the hydraulic circuit and reducing the weight of the hydraulic circuit by reducing the number of solenoid valves compared to other embodiments of the present disclosure.

[0093] The second-stage boosting operation, in which the brake fluid in the first main flow path 165a is returned to the first main chamber 125, may use the other embodiment having the fourth backup valve 197 or the at least one embodiment without the fourth backup valve 197 in the hydraulic circuit configuration. Other than the presence or absence of the fourth backup valve 197, the solenoid valves may remain the same in design and function to implement the present disclosure.

[0094] Fig. 6 shows a block diagram of the electric hydraulic brake according to at least one embodiment having a second brake flow path in a fault condition, showing a flow of the brake fluid and opening / closing states of the solenoid valves.

[0095] Fig. 7 is a block diagram of the electric hydraulic brake according to another embodiment having a second brake flow path in a failure state, showing a flow of the brake fluid and opening / closing states of the solenoid valves.

[0096] As in the Fig. 6 and Fig.As shown in Figure 7, dashed squares on the solenoid valves represent those that are actuated by receiving power from the control unit 140. Whereas, the solenoid valves without a dashed square represent those that are not actuated during a first-stage pressure relief operation. A square on the solenoid valve indicated by a dashed line represents a solenoid valve that is actuated by receiving power from the control unit 140. Furthermore, the third brake w3 and the second brake w4, indicated by hatching, indicate a situation where a fault occurs in the second brake flow path 163.

[0097] When a fault occurs in the second brake flow path 163 according to another embodiment of the present disclosure, the control unit 140 opens the fourth backup valve 197 and moves the master piston 122 forward or backward to return the brake fluid in the first master chamber 125 to the reservoir.

[0098] However, the electric hydraulic brake according to at least one embodiment of the present disclosure, which does not have a fourth backup valve 197, responds to a fault occurring in the second brake flow path 163 to lower the pressure in the hydraulic circuit by means of the third outlet valve 187 and the fourth outlet valve 188.

[0099] The control unit 140 supplies power to the third outlet valve 187 and the fourth outlet valve 188, which are configured as normally closed valves, to open them. When the third outlet valve 187 and the fourth outlet valve 188 are open, the brake fluid in the second brake flow path 163 flows through the third outlet valve 187 and the fourth outlet valve 188 and the fourth return flow path 168 until it is returned to the reservoir.

[0100] Therefore, when a fault occurs in the second brake flow path 163, the other embodiment of the present disclosure uses the fourth backup valve 197 to return the brake fluid in the second brake flow path 163, and the at least one embodiment returns the brake fluid in the second brake flow path 163 by means of the third outlet valve 187 and the fourth outlet valve 188.

[0101] Accordingly, the at least one embodiment of the present disclosure requires fewer solenoid valves than the other embodiment, thereby reducing the manufacturing cost of the hydraulic circuit and the weight of the hydraulic circuit.

[0102] On the other hand, a possible fault occurring in the second brake flow path 163 is irrelevant to the actuation of the fourth backup valve 197. The present disclosure may provide a hydraulic circuit configured either in the other embodiment including the fourth backup valve 197 or in the at least one embodiment without the fourth backup valve 197. With or without the fourth backup valve 197, the solenoid valves may remain the same in design and function to implement the present disclosure.

[0103] As described above, according to some embodiments of the present disclosure, solenoid valves that are used only in a specific mode and have a low operating frequency are eliminated, and a backup valve and an exhaust valve are used to take over the capacity of the eliminated solenoid valves in their place to reduce the number of solenoid valves within the electric hydraulic brake device, thereby making the electric hydraulic brake device lighter.

[0104] Although embodiments of the present disclosure have been described for illustrative purposes, it will be apparent to those skilled in the art that various modifications, additions, and substitutions are possible without departing from the spirit and scope of the claimed invention. Therefore, embodiments of the present disclosure have been described for the sake of conciseness and clarity. The scope of the technical idea of the present embodiments is not limited by the illustrations. Accordingly, one of ordinary skill in the art would understand that the scope of the claimed invention is not to be limited by the embodiments explicitly described above, but rather by their claims and equivalents.

Claims

[1] Device for electro-hydraulic braking, comprising: a reservoir configured to store brake fluid; a backup brake cylinder (110) configured to respond to a brake pedal operation to change a pressure of the brake fluid in the backup brake cylinder (110); a motor (152) configured to generate rotational power based on a motor control signal; a master brake cylinder (120) with a main piston (122) which is designed to move together with the rotational power of the engine before and moves back and changes the pressure of the brake fluid in the master cylinder (120); a plurality of wheel brakes (w1, w2, w3, w4), each adapted to generate a braking force at each of the wheels; and an electronic control unit (ECU,140) configured to generate the engine control signal and a valve control signal so that the wheel brakes (w1,w2,w3,w4) generate a braking force based on a brake pedal operation; and a hydraulic circuit valve device having a backup valve (194, 195, 196, 197) configured to be operable based on the valve control signal to change a flow path of the fluid flowing within the hydraulic circuit valve device and to open and close a backup flow path (171, 172, 173, 174, 175, 176) between the backup brake cylinder (110) and the master brake cylinder (120), characterized by , that the electronic control unit (140) reacts to the opening of the backup valve (194,195,196,197) when performing a hydraulic pressure reduction of the brake fluid in the hydraulic circuit valve device so that the brake fluid discharged from the master cylinder (120) is returned to the reservoir through a brake flow path (161,163). [2] Device according to claim 1, wherein the master brake cylinder (120) has: a first main chamber (125) having an interior which is narrowed towards the point at which the main piston (122) moves forward, and a second main chamber (126) having an interior space which is widened towards the point at which the main piston (122) advances, the backup brake cylinder (110) has: a first backup chamber (118) configured to supply the brake fluid to the second main chamber (125), and a second backup chamber (119) configured to supply the brake fluid to the second main chamber (126), and the hydraulic circuit valve device comprises: one or more main flow paths (165a,165b), each designed to pass through a main brake cylinder (120) formed in the main brake cylinder Transfer hydraulic pressure to the brake flow path (161,163), where the device further comprises: a first traction control valve (191) configured to open and close one of the main flow paths (165a, 165b), and a second traction control valve (192) configured to open and close another of the main flow paths (165a,165b). [3] Device according to claim 2, wherein the main flow path (165a,165b) has: a first main flow path (165a) equipped with the second traction control valve (192), and a second main flow path (165b) equipped with the first traction control valve (191), the backup valve (194,195,196,197) has: a solenoid valve connected to the second main flow path (165b), and the electronic control unit (140) is designed to control the backup valve (194, 195, 196, 197) so that the brake fluid discharged into the first main flow path (165a) is returned to the reservoir through the second main flow path (165b), thereby carrying out the hydraulic pressure reduction. [4] Apparatus according to claim 3, wherein the backup valve (194,195,196,197) comprises: a normally open type valve. [5] Device according to claim 2, wherein the first traction control valve (191) comprises: a normally open type valve, and the second traction control valve (192) comprises: a normally open type valve. [6] Device according to claim 2, wherein the hydraulic circuit valve device comprises: a plurality of outlet valves (185, 186, 187, 188) configured to open and close a return flow path (162, 164, 166, 168) through which brake fluid supplied to the plurality of wheel brakes (w1, w2, w3, w4) is returned to the reservoir, and the brake flow path (161,163) is designed to distribute a hydraulic pressure in the hydraulic circuit valve device to the plurality of wheel brakes (w1,w2,w3,w4) and comprises: a first brake flow path (161) connected to the first traction control valve (191), and a second brake flow path (163) connected to the second traction control valve (192), where the electronic control unit (140) reacts to a fault occurring in the second brake flow path (163) to open an outlet valve (185,186,187,188) connected to the second brake flow path (163) so that the brake fluid is returned to the reservoir. [7] Device according to claim 6, wherein the hydraulic circuit valve device comprises: a mixing valve (193) configured to connect the first brake flow path (161) and the second brake flow path (163) and to be opened on the basis of the valve control signal so that the brake fluid in the first brake flow path (163) can be transferred to the second brake flow path (163), and the electronic control unit (140) reacts to a fault occurring in the second brake flow path (163) to open the outlet valve (185,186,187,188) so that the brake fluid is returned to the reservoir. [8] Apparatus according to claim 7, wherein the mixing valve (193) comprises: a normally closed type valve. [9] Apparatus according to claim 7, wherein the outlet valve (185,186,187,188) comprises: a normally closed type valve.

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