Integrated electro-hydraulic braking system

Abstract

Integrated electro-hydraulic braking system, which features: an energy source unit (200) comprising an accumulator (230) configured to store pressure at a predetermined level, a pump (210) configured to draw oil from a container (115) and deliver the oil to the accumulator (230) to generate pressure in the accumulator (230), and a motor (220) configured to drive the pump (210); an integrated hydraulic control device (100) comprising a master cylinder (110) with two hydraulic circuits (HC1, HC2) and configured to generate hydraulic pressure, a reservoir (115) connected above the master cylinder (110) and configured to store oil, an inlet valve (141, 142) and an outlet valve (143, 144) configured to control pressure supplied from the accumulator (230) to a wheel cylinder (20) installed in each wheel, a shut-off valve (173, 174) configured to control fluid pressure supplied from the master cylinder (110) to the wheel cylinder (20), a pedal simulator (180) connected to the master cylinder (110) and configured to provide a brake pedal (30) response force, and a simulation valve (186) installed in a rear end of the pedal simulator (180); and a control valve (150) which is arranged and configured in a connecting passage connecting the outlet valve (143, 144) and the container (115) to perform a control such that the fluid pressure flowing through the outlet valve (143, 144) flows towards the container (115), wherein the energy source unit (200) is provided as a separate unit to isolate operating noise, and the integrated hydraulic control device (100) and the energy source unit (200) are connected by an external line (10), wherein the outlet valve (143, 144) is provided as a normally open type solenoid valve used in low current ranges, normally maintains an open state to reduce heat generation but closes when a closing signal is received, compared to a normally closed type solenoid valve which normally maintains a closed state, and wherein the control valve (150) is provided as a normally closed solenoid valve which normally maintains a closed state to prevent the fluid pressure generated by the master cylinder (110) from flowing to the reservoir (115) when the integrated electro-hydraulic brake system is operating anomalously.

Description

CROSS-REFERENCE TO RELATED REGISTRATION

[0001] This application claims the benefits of Korean patent application No. P2013-0155090, which was filed with the Korean Intellectual Property Office on December 13, 2013, and whose disclosure is incorporated herein. BACKGROUND 1. Area

[0002] Exemplary embodiments of the present invention relate to an electro-hydraulic braking system, and in particular to an integrated electro-hydraulic braking system which provides an actuating part containing a master cylinder, a pedal simulator and the like, electronic stability control (ESC), and a hydraulic power unit (HPU) as a single unit. 2. Description of the state of the art

[0003] More recently, in order to improve fuel efficiency and reduce emissions, the development of hybrid vehicles, fuel cell vehicles, electric cars, and the like has been actively promoted. A braking device, that is, a braking component of an automotive braking system, is necessarily installed in such vehicles. Here, the automotive braking device refers to a device that reduces the speed of a moving vehicle or brings the vehicle to a stop.

[0004] A braking device of a typical automotive braking system includes a vacuum brake configured to generate braking energy using a suction pressure from a machine, and a hydraulic brake configured to generate braking energy using hydraulic pressure.

[0005] The vacuum brake is a device that can generate high braking energy with a small force by utilizing a pressure differential between the suction pressure of a vehicle's engine and atmospheric pressure in a vacuum booster. This means it produces significantly more braking energy compared to the force applied to the brake pedal by a driver. However, with a vacuum brake, the vehicle's engine suction pressure must be supplied to the vacuum booster to create a vacuum. Therefore, fuel efficiency decreases, and the engine must be continuously operated to maintain a vacuum, even when the vehicle is stationary.

[0006] Additionally, since fuel cell vehicles and electric cars lack a mechanical brake system, the application of an existing vacuum brake, configured to amplify driver pedal force during braking, is unsuitable. Hybrid vehicles must incorporate a hydraulic brake because an idle-stop function is required to improve fuel efficiency when the vehicle is stationary.

[0007] This means that, as described above, all vehicles must implement regenerative braking to improve fuel efficiency. If hydraulic brakes are already in use, their implementation is straightforward.

[0008] Fig. Figure 1 illustrates an electro-hydraulic braking system, which is a type of hydraulic brake. In the electro-hydraulic braking system, when the driver presses the pedal, an electronic control unit detects the pressing action, and hydraulic brake pressure is delivered to a master cylinder and a wheel cylinder of each wheel, thereby generating braking energy.

[0009] As in Fig. As illustrated in Figure 1, the electro-hydraulic braking system comprises an actuating unit 1 with a master cylinder 1a, a booster unit 1b, a reservoir 1c, a pedal simulator 1d, and the like, which control a hydraulic brake pressure supplied to a wheel cylinder 20; a modulator module 2, configured to independently control the braking energy of each wheel; and a hydraulic power unit (HPU) 3 with a motor, a pump, an accumulator, a valve, and the like. In this case, depending on the braking control method, an anti-lock braking system (ABS), a traction control system (TCS), an electronic stability control system (ESC), and the like can be selectively applied at the modulator module 2.

[0010] However, since each of the units 1, 2, and 3 that make up the electro-hydraulic braking system is designed and installed separately, installation space must be ensured due to the limited installation space of the vehicle, and the weight increases. Therefore, the electro-hydraulic braking system must ensure vehicle safety, increased fuel efficiency, adequate pedal feel, and the like during braking, and an improved electro-hydraulic braking system is required.

[0011] If an exhaust valve configured to control pressure from the wheel cylinder out of the valves used in the modulator module uses a normally closed solenoid valve that normally maintains a closed state according to its control characteristic, the elasticity of a spring blocking the passage is high. To open the passage, since high current ranges must be used, the control characteristic deteriorates and heat generation is high.

[0012] Therefore, in accordance with the aforementioned requirements, investigations are being carried out regarding the development of an electro-hydraulic braking system that has a simple configuration, is able to implement braking energy without interference, even if a fault occurs, and is easy to control.

[0013] US 2013 / 0241273 A1 discloses an integrated electro-hydraulic braking system comprising an actuator containing a master cylinder and a pedal simulator, an electronic stability control unit, and a hydraulic power source unit, the power source unit being a separate unit. US 6 007 165 A discloses a traction control system in which a control valve is provided in a connecting passage between an outlet valve and a reservoir to release excess pressure into the reservoir during system operation. SUMMARY

[0014] In view of the problems described above, the present invention provides an integrated electro-hydraulic braking system which has a simple configuration to improve braking safety and is easy to install in the vehicle, provides a stable pedal feel during braking, and is able to improve fuel efficiency by supporting regenerative braking.

[0015] The present invention also provides an integrated electro-hydraulic braking system that enables rapid control by changing the type of valve configured to control a flow of hydraulic pressure and capable of stably controlling the flow of hydraulic pressure even when the type of valve is changed.

[0016] This problem is solved by an integrated electro-hydraulic braking system according to claim 1. According to one aspect of the present invention, an integrated electro-hydraulic braking system is provided. The system includes a power source unit comprising an accumulator configured to store pressure at a predetermined level, a pump configured to draw oil from a reservoir and discharge the oil to the accumulator to generate pressure in the accumulator, and a motor configured to drive the pump; and an integrated hydraulic control device comprising a master cylinder with two hydraulic circuits, configured to generate hydraulic pressure, a reservoir connected above the master cylinder and configured to store oil, an inlet valve, and an outlet valve configured toto control a pressure supplied from the accumulator to a wheel cylinder installed in each wheel, a shut-off valve configured to control a fluid pressure supplied from the master cylinder to the wheel cylinder, a pedal simulator connected to the master cylinder and configured to provide a brake pedal response force, and a simulation valve installed in a rear end of the pedal simulator, wherein the power source unit is provided as a separate unit to isolate operating noise, and the integrated hydraulic control device and the power source unit are connected by an external line, and the outlet valve is provided as a normally open type solenoid valve used in low current ranges, normally maintaining an open state to reduce heat generation, but closing when a closing signal is received.compared to a normally closed solenoid valve, which normally maintains a closed state.

[0017] The system also includes a control valve located in a connecting passage linking the outlet valve and the reservoir, and configured to perform control such that the fluid pressure flowing through the outlet valve flows towards the reservoir.

[0018] The control valve is designed as a normally closed solenoid valve, which normally maintains a closed state to prevent the fluid pressure generated by the master cylinder from flowing towards the reservoir when the integrated electro-hydraulic braking system is operating anomalously.

[0019] A simulation check valve can be provided between the pedal simulator and the simulation valve; an outlet pressure of the pedal simulator due to a pedal force of the brake pedal can only be supplied through the simulation valve; and when the pedal force of the brake pedal is released, oil can be drawn in through the simulation check valve and stored in the pedal simulator; and the simulation check valve can be connected to the reservoir by an oil passage.

[0020] The external line can connect the accumulator and a hydraulic pressure port connected to the inlet valve, and a check valve can be installed in the hydraulic pressure port to prevent backflow of pressure.

[0021] The integrated hydraulic control device can include a first and a second safety bypass that connect the master cylinder and the two hydraulic circuits to control brake fluid when the integrated electro-hydraulic brake system operates anomalously, and the shut-off valve can include a first shut-off valve installed and configured in the first safety bypass to control a connection with the master cylinder, and a second shut-off valve installed and configured in the second safety bypass to control a connection with the master cylinder.

[0022] The first and second shut-off valves can be designed as normally open solenoid valves, which normally maintain an open state but are closed in a normal braking condition.

[0023] Each of the hydraulic circuits may include a normally open solenoid valve located upstream of the wheel cylinder and configured to control the supply of fluid pressure to the wheel cylinder, a normally closed solenoid valve located downstream of the wheel cylinder and configured to control the output of fluid pressure from the wheel cylinder, and a return passage connecting the normally closed solenoid valve to the reservoir, and the return passage may be connected to the simulation valve.

[0024] An impulse damper configured to minimize pressure impulses may be provided in an inlet passage connecting the inlet valve, the outlet valve, and the two hydraulic circuits.

[0025] The inlet valve can be designed as a normally closed solenoid valve, which normally maintains a closed state. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention is described in detail with reference to the accompanying drawings. Since these drawings illustrate embodiments of the present invention, the spirit and scope of the present invention are not defined or limited by these drawings. Fig. Figure 1 is a diagram that schematically illustrates a configuration of a conventional electro-hydraulic braking system; Fig. Figure 2 is a hydraulic circuit diagram illustrating a non-braking state of an integrated electro-hydraulic braking system according to an embodiment of the present invention; Fig. Figure 3 is a hydraulic circuit diagram illustrating a normal operating state of the integrated electro-hydraulic braking system according to the embodiment of the present invention; and Fig. Figure 4 is a hydraulic pie chart illustrating an anomalous operating condition of the integrated electro-hydraulic brake system according to the embodiment of the present invention. DETAILED DESCRIPTION

[0027] Exemplary embodiments of the present invention are described in detail below with reference to the accompanying drawings. Terms and words used in this description and in the claims should not be interpreted as being limited to commonly used meanings or dictionary definitions, but should be interpreted with meanings and concepts consistent with the technological scope of the invention, based on the principle that the inventors have adequately defined concepts of terms to best describe the invention. Therefore, it should be noted that the exemplary embodiments described herein and the configurations illustrated in the drawings are only exemplary embodiments and do not represent the entire technological scope of the invention. It should also be noted that the invention covers various equivalents, modifications, and substitutions at the time of filing of this application.

[0028] Fig. Figure 2 is a hydraulic circuit diagram illustrating an integrated electro-hydraulic braking system according to an embodiment of the present invention.

[0029] The integrated electro-hydraulic braking system according to the present invention can mainly comprise two units, such as an integrated hydraulic control device 100 and an energy source unit 200. As shown in Fig. As illustrated in Figure 2, the integrated hydraulic control device 100 includes a brake pedal 30, which is actuated by a driver during braking, a master cylinder 110, which is configured to receive a force from the brake pedal 30, a reservoir 115, which is connected above the master cylinder 110 and configured to store oil, a hydraulic circuit HC1, which is connected to two wheels RL and FR, and a hydraulic circuit HC2, which is connected to two wheels FL and RR, a pedal simulator 180, which is connected to the master cylinder 110 and configured to provide a reaction force from the brake pedal 30, and a simulation valve 186, which is installed in a passage 188, which connects the pedal simulator 180 and the reservoir 115.The energy source unit 200 contains an accumulator 230 configured to store pressure at a predetermined level, a pump 210 configured to draw oil from the reservoir 115 and discharge the oil to the accumulator 230 to generate pressure in the accumulator 230, and a motor 220 configured to drive the pump 210.

[0030] In addition, the integrated hydraulic control device 100 can further include pressure sensors 101, 102 and 103, inlet valves 141 and 142 and outlet valves 143 and 144, which are connected to the two hydraulic circuits HC1 and HC2, and the like, to control a pressure supplied from the reservoir 115 or the accumulator 230 to the wheel cylinders 20 installed in the wheels FL, FR, RL and RR.

[0031] In this case, the integrated hydraulic control device 100 and the power source unit 200 are connected by an external line 10. That is, the accumulator 230 of the power source unit 200 and a hydraulic pressure port 120 of the integrated hydraulic control device 100 are connected by the external line 10. The power source unit 200, which contains the pump 210, the motor 220, and the accumulator 230, is configured as a separate unit to isolate operating noise. If the master cylinder 110, the reservoir 115, and the pedal simulator 180 are provided as a single unit in the integrated hydraulic control device 100, and if the functions of an electronic stability control (ESC) module and a hydraulic power unit (HPU) module are included, it is possible to reduce the weight of the entire integrated electro-hydraulic braking system and improve installation space.

[0032] The structures and functions of the respective components of the integrated electro-hydraulic braking system are described in detail.

[0033] The master cylinder 110 is capable of generating fluid pressure using a single chamber, but in this embodiment, two chambers are used to ensure safety in case of failure. A first piston 111 and a second piston 112 are provided within the chamber. The first and second pistons 111 and 112 are pressurized by an input rod 31, which is connected to the brake pedal 30, according to a pedal force of the brake pedal 30, generating hydraulic pressure and connected to the two hydraulic circuits HC1 and HC2, respectively. The master cylinder 110 receives oil through the reservoir 115 installed on the upper side and discharges the oil to the wheel cylinders 20 installed in the wheels RR, RL, FR, and FL through outlets installed on the lower side.

[0034] While in this case, as in Fig. Figure 2 illustrates the integrated electro-hydraulic braking system as installed in an X-shaped (cross-split) vehicle. However, the present invention is not limited to this. Here, the cross-split vehicle refers to a vehicle that performs the braking of the front and rear wheels in a crosswise manner, with two front wheels FL and FR and two rear wheels RL and RR being controlled. That is, between the two hydraulic circuits HC1 and HC2, the first hydraulic circuit HC1 is connected to the right front wheel FR and the left rear wheel RL of the vehicle, and the second hydraulic circuit HC2 is connected to the left front wheel FL and the right rear wheel RR.

[0035] Hydraulic circuits HC1 and HC2 contain a passage connected to wheel cylinder 20, and several valves 161 and 162, configured to control fluid pressure, are installed in the passage. As illustrated, the multiple valves 161 and 162 are classified as the normally open solenoid valve 161 (hereinafter referred to as a "NO type"), located upstream of wheel cylinder 20 and controlling the supply of fluid pressure to the wheel cylinder, or as the normally closed solenoid valve 162 (hereinafter referred to as a "NC type"), located downstream of wheel cylinder 20 and controlling the output of fluid pressure from wheel cylinder 20. The operation of opening and closing the solenoid valves 161 and 162 can be controlled by a commonly used electronic control unit (not illustrated).

[0036] Additionally, each of the hydraulic circuits HC1 and HC2 contains a return passage 160, which connects the normally closed (NC) solenoid valve 162 and the reservoir 115. The return passage 160 is configured to return the fluid pressure supplied to the wheel cylinder 20 and to supply the pressure to the reservoir 115. The return passage 160 is connected to the reservoir 115 and also to passage 188, in which the simulation valve 186, described below, is installed. Therefore, when the simulation valve 186 is open to allow the flow of fluid pressure from the pedal simulator 180, the pressure is supplied to the reservoir 115.

[0037] At least one pump 210 is provided to generate brake pressure by pumping the oil supplied from reservoir 115 under high pressure. The motor 220, configured to supply a driving force to the pump 210, is located on one side of the pump 210. The motor 220 can be driven by receiving a braking intention from the driver, resulting from a pedal force of the brake pedal 30 from the second pressure sensor 102 or a pedal displacement sensor (not illustrated), as described below.

[0038] The accumulator 230 is located on one outlet side of the pump 210 and temporarily stores the high-pressure oil generated by the drive of the pump 210. That is, as described above, the accumulator 230 is connected to the hydraulic pressure port 120 via the external line 10.

[0039] A check valve 125 is provided in the hydraulic pressure port 120 to prevent backflow of oil. Additionally, the first pressure sensor 101 is provided in the hydraulic pressure port 120 to measure the oil pressure of the accumulator 230. At this time, the electronic control unit (not illustrated) compares the oil pressure measured by the first pressure sensor 101 with a set pressure. If the measured pressure is lower than the set pressure, the pump 210 is driven to draw oil from the reservoir 115, and the accumulator 230 is filled with oil. The hydraulic pressure port 120 is connected to the hydraulic circuits HC1 and HC2 via the inlet ports 131 and 132.

[0040] Inlet ports 131 and 132 contain the first inlet port 131, which is connected to the first hydraulic circuit HC1, and the second inlet port 132, which is connected to the second hydraulic circuit HC2. The first inlet port 131 contains the first inlet valve 141 and the first outlet valve 143, which are configured to control the brake fluid stored in the accumulator 230. The second inlet port 132 contains the second inlet valve 142 and the second outlet valve 144, which are configured to control the brake fluid stored in the accumulator 230. That is, the brake fluid from the accumulator 230 can be supplied to each of the wheel cylinders 20 through the first inlet port 131 and the second inlet port 132.

[0041] The first and second inlet valves 141 and 142 are configured as NC-type solenoid valves, which normally maintain a closed state. The first and second outlet valves 143 and 144 are configured as NO-type solenoid valves, which normally maintain an open state. Therefore, when the driver presses the brake pedal 30, the first and second inlet valves 141 and 142 open, the brake fluid stored in the accumulator 230 is supplied to the wheel cylinder 20, and the first and second outlet valves 143 and 144 are closed.

[0042] According to the embodiment of the present invention, a control valve 150 is provided in a connecting passage 154, which connects the return passage 160 connected to the reservoir 115 and the outlet valves 143 and 144, to control the flow of fluid pressure through the outlet valves 143 and 144 to the reservoir 115. The control valve 150 is configured as a normally closed (NC) type solenoid valve, which normally maintains a closed state and opens when the fluid pressure is reduced to such an extent that oil is supplied to the reservoir 115. The control valve 150 also normally maintains a closed state and prevents the fluid pressure generated by the master cylinder 110 from flowing to the reservoir 115 when the integrated electro-hydraulic brake system is operating abnormally.

[0043] The integrated hydraulic control device 100 can further include an impulse damper 135, which is provided in the first inlet passage 131 and the second inlet passage 132 and minimizes pressure impulses. The impulse damper 135 is a device that can temporarily store oil to reduce impulses generated between the inlet valves 141 and 142, the exhaust valves 143 and 144, and the NO-type solenoid valve 161. Since the impulse damper is a well-known technology in this field, a detailed description of it is omitted.

[0044] The unspecified reference number “103” designates the third pressure sensor, which is installed in the first and second inlet passages 131 and 132 and detects a hydraulic brake pressure supplied to the inlet passages 131 and 132. Therefore, the impulse damper 135 can be controlled to reduce the impulses according to the brake oil pressure detected by the third pressure sensor 103.

[0045] According to the present invention, a first safety passage 171 and a second safety passage 172 can be provided to connect the master cylinder 110 and the two hydraulic circuits HC1 and HC2 in the event of a failure of the integrated electro-hydraulic braking system. A first shut-off valve 173, configured to open and close the first safety passage 171, is provided in the center of the first safety passage 171. A second shut-off valve 174, configured to open and close the second safety passage 172, is provided in the center of the second safety passage 172. The first safety passage 171 is connected to the first inlet passage 131 via the first shut-off valve 173. The second safety passage 172 is connected to the second inlet passage 132 via the second shut-off valve 174.In particular, the second pressure sensor 102, configured to measure the oil pressure of the master cylinder 110, can be located between the first shut-off valve 173 and the master cylinder 110. In a normal braking condition, the safety passages 171 and 172 are blocked by the first shut-off valve 173 and the second shut-off valve 174, and a braking intention requested by the driver can be determined by the second pressure sensor 102.

[0046] The first and second shut-off valves 173 and 174 are configured as normally open (NO) type solenoid valves, which are normally open but closed in a normal braking condition. Therefore, when the hydraulic brake pressure is supplied to the wheel cylinder 20 through the first and second inlet passages 131 and 132, the first and second shut-off valves 173 and 174 are closed, the oil does not flow through the safety passages 171 and 172, and is supplied to the wheel cylinder 20 without interference.

[0047] According to the present invention, the pedal simulator 180, which is configured to generate a pedal force of the brake pedal 30, is provided between the second pressure sensor 102 and the master cylinder 110.

[0048] The pedal simulator 180 includes a simulation chamber 180 configured to store oil discharged from an outlet side of the master cylinder 110, and the simulation valve 186 connected to a rear end of the simulation chamber 182. The simulation chamber 182 contains a piston 183 and an elastic part 184 and is designed to displace a predetermined level of oil introduced into the simulation chamber 182.

[0049] The simulation valve 186 is connected to the passage 188, which connects a rear end of the pedal simulator 180 and the reservoir 115. As illustrated, an inlet of the pedal simulator 180 is connected to the master cylinder 110, the simulation valve 186 is installed in a rear end of the pedal simulator 180, and an outlet of the simulation valve 186 is connected to the return passage 160, which is connected to the reservoir 115 via the passage 188. Therefore, the pedal simulator 180, that is, the entire interior of the simulation chamber 182, is filled with oil.

[0050] The simulation valve 186 is configured as an NC-type solenoid valve, which normally maintains a closed state but is open when the driver presses against the brake pedal 30.

[0051] Additionally, a simulation check valve 185 is provided between the pedal simulator 180 and the master cylinder 110, i.e., between the pedal simulator 180 and the simulation valve 186. The simulation check valve 185 is connected to the reservoir 115 via an oil passage 189 such that the oil flows from the reservoir 115 to the simulation chamber 182. The simulation check valve 185 is configured to supply an outlet pressure from the pedal simulator 180, triggered by the pedal force of the brake pedal 30, only through the simulation valve 186. In other words, when the piston 183 of the pedal simulator 180 compresses the spring 184, the oil in the simulation chamber 182 is supplied through the simulation valve 186 and the passage 188 to the reservoir 115.Therefore, since the interior of the simulation chamber 182 is filled with oil when the pedal simulator 180 is actuated, friction of the piston 183 is minimized, the durability of the pedal simulator 180 is improved, and the introduction of foreign materials from outside is blocked.

[0052] Additionally, when the pedal force of the brake pedal 30 is released, the oil is supplied to the simulation chamber 182 via the simulation check valve 185, thus ensuring a rapid return of pressure to the pedal simulator 180. The simulation check valve 185 is preferably configured as a line check valve without a spring, such that residual pressure in the pedal simulator 180 is restored when the pedal force of the brake pedal 30 is released.

[0053] The integrated hydraulic control device 100 described above can be provided as a single block containing the electronic control unit (ECU: not illustrated), which is electrically connected to and controls each valve and sensor. Accordingly, it is possible to implement a compact, integrated electro-hydraulic braking system. That is, the integrated electro-hydraulic braking system according to the embodiment of the present invention can easily accommodate the available installation space and avoid the problem of weight gain caused by the integrated hydraulic control device 100, in which the power source unit 200, comprising the motor 220, the pump 210, and the accumulator 230, various types of valves and sensors, and the pedal simulator 180, configured to generate a pedal force from the brake pedal 30, are provided in the form of a single block.

[0054] The operation of an integrated electro-hydraulic braking system according to an embodiment of the present invention is described in detail below.

[0055] Fig. Figure 3 is a hydraulic pie chart illustrating a normal operating state of the integrated electro-hydraulic braking system.

[0056] As in Fig. As illustrated in Figure 3, when the driver begins braking, the driver-requested braking intensity can be detected based on pressure information from the second pressure sensor 102, the pedal displacement sensor (not illustrated), and similar sources via the brake pedal 30 depressed by the driver. The ECU (not illustrated) can receive a value for the amount of regenerating brakes and calculate a value for friction based on the difference between the amount of braking requested by the driver and the amount of regenerating brakes. Accordingly, it is possible to determine the magnitude of increased or decreased pressure on one side of the wheel.

[0057] In particular, if the driver presses the brake pedal 30 during initial braking, the system can be controlled in such a way that the vehicle's braking is carried out entirely by regenerative braking, and no braking force is generated due to friction. Therefore, it is necessary to reduce the brake fluid pressure so that the hydraulic pressure supplied to the brake pedal 30 and generated in the master cylinder 110 is not delivered to the wheel cylinders 20. At this time, when the outlet valves 143 and 144 are open and the hydraulic pressure generated in the inlet ports 131 and 132 is discharged to the reservoir 115, no pressure is generated in the wheels RR, RL, FR, and FL, and the brake pedal pressure can be maintained without change.

[0058] Then, a process of regulating the friction brake size according to a change in the regenerable brake size can be carried out. The regenerable brake size is changed according to the state of charge of a battery or the speed of the vehicle. The regenerable brake size decreases considerably below a predetermined vehicle speed. To manage such a situation, the first inlet valve 141 can control a flow rate of the brake fluid supplied from the accumulator 230 to the first inlet passage 131 in order to control a hydraulic pressure of the wheel cylinder 20. In the same way, the second inlet valve 142 can control a flow rate of the brake fluid supplied from the accumulator 230 to the second inlet passage 132.

[0059] Since there is no recoverable braking amount, braking can then be carried out according to a general braking condition.

[0060] The pressure generated by pressing the master cylinder 110, resulting from the pedal force of the brake pedal 30, is supplied to the pedal simulator 180 connected to the master cylinder 110. At this time, the simulation valve 186, installed in the passage 188 connecting a rear end of the pedal simulator 180 and the reservoir 115, opens, and the oil filled into the simulation chamber 182 is supplied through the simulation valve 186 to the reservoir 115. Additionally, pressure corresponding to the loads on the piston 183 and the spring 184 supporting the piston 183 provides appropriate pedal feel to the driver through the simulation chamber 182. When the pedal force of the brake pedal 30 is released, the oil is additionally supplied to the simulation chamber 182 through the simulation check valve 185, thus ensuring a rapid return of pressure to the pedal simulator 180.

[0061] Fig. Figure 4 is a hydraulic pie chart illustrating a case in which the integrated electro-hydraulic braking system is operating anomalously.

[0062] As in Fig.As illustrated in Figure 4, when the integrated electro-hydraulic braking system malfunctions, the fluid pressure is supplied through the first and second safety passages 171 and 172 to the wheel cylinder 20 to perform a safety brake application, and the braking energy is applied. At this time, the first and second shut-off valves 173 and 174, installed in the first and second safety passages 171 and 172, and the normally open (NO) solenoid valves 161 of the two hydraulic circuits HC1 and HC2 are open, while the control valve 150, connected to the first and second inlet valves 141 and 142, and the first and second outlet valves 143 and 144, configured as normally closed (NC) solenoids, are closed. Accordingly, the fluid pressure is supplied directly to the wheel cylinder 20.Additionally, in the pedal simulator 180, which is connected below the master cylinder 110, the simulation valve 186 is configured as a normally closed (NC) type solenoid valve. When the flow of oil through the simulation check valve 185, which is configured to control one-way flow, is blocked, the fluid pressure is efficiently delivered to the wheel cylinder 20. Therefore, since safe braking can be performed, it is possible to improve braking safety.

[0063] The master cylinder 110 is preferably designed to have a smaller inner diameter than a conventional master cylinder, such that the mechanical braking capacity is maximized according to the pedal force of the brake pedal 30. That is to say, the master cylinder has a smaller inner diameter than an existing master cylinder, and sufficient braking energy can be exerted by the brake fluid stored in the reduced inner diameter, even if the inner diameter decreases.

[0064] The integrated electro-hydraulic braking system according to the embodiment of the present invention has the following effects.

[0065] Firstly, it is possible to easily provide an installation space, address a problem caused by increased weight, and ensure easy assembly due to an integrated hydraulic control device in which a power source unit with a motor, pump and accumulator, a master cylinder, various types of valves and sensors, and a pedal simulator configured to generate a pedal force of a brake pedal are provided in the form of a single block.

[0066] Secondly, because an outlet valve is designed as a normally open solenoid valve, which is used in low-flow ranges and generates little heat, it is possible to improve the control characteristics when the brake is released. Additionally, a control valve, also designed as a normally closed solenoid valve, is located separately in a passage connecting the outlet valve and a reservoir. Therefore, even if the system malfunctions, it is possible to prevent pressure from escaping to the reservoir, thus ensuring stable control of the hydraulic pressure flow.

[0067] Thirdly, when the pedal simulator is connected to the reservoir and a simulation valve is provided to control it, oil is stored in the pedal simulator. This improves the durability of the pedal simulator and prevents the ingress of foreign materials. Additionally, residual pressure is minimized by a springless simulation check valve, and a stable pedal feel is maintained for the driver, even if the pressure is arbitrarily adjusted during braking.

[0068] Fourthly, since it is possible to brake the vehicle in the event of a failure of the braking system, the system can easily be applied to electric motor vehicles, fuel cell vehicles and hybrid vehicles.

[0069] Fifthly, regardless of the machine and its operation, it is possible to implement braking energy requested by the driver, which contributes to an improvement in fuel efficiency.

[0070] Sixth, because the system has a simpler configuration than a conventional negative pressure booster and, unlike a vacuum brake, does not use the machine's suction pressure, it is possible to improve the vehicle's fuel efficiency. Due to its simple configuration, it is easy to apply to small cars.

[0071] While the present invention has been described with reference to specific embodiments and drawings, the invention is not limited thereto. It is obvious to the person skilled in the art that various modifications and changes can be made without departing from the spirit and scope of the present invention and equivalents of the appended claims.

Claims

Integrated electro-hydraulic braking system comprising: a power source unit (200) containing an accumulator (230) configured to store pressure at a predetermined level, a pump (210) configured to draw oil from a reservoir (115) and discharge the oil to the accumulator (230) to generate pressure in the accumulator (230), and a motor (220) configured to drive the pump (210); an integrated hydraulic control device (100) comprising a master cylinder (110) with two hydraulic circuits (HC1, HC2) configured to generate hydraulic pressure, a reservoir (115) connected above the master cylinder (110) and configured to store oil, an inlet valve (141, 142) and an outlet valve (143, 144) configured to supply pressure from the accumulator (230) to one in each wheel installed wheel cylinder (20) to control the supplied pressure, a shut-off valve (173, 174),which is configured to control a fluid pressure supplied from the master cylinder (110) to the wheel cylinder (20), a pedal simulator (180) which is connected to the master cylinder (110) and configured to provide a reaction force of a brake pedal (30), and a simulation valve (186) which is installed in a rear end of the pedal simulator (180); and a control valve (150) which is arranged and configured in a connecting passage connecting the outlet valve (143, 144) and the reservoir (115) to perform control such that the fluid pressure flowing through the outlet valve (143, 144) flows towards the reservoir (115), wherein the power source unit (200) is provided as a separate unit to isolate operating noise, and the integrated hydraulic control device (100) and the power source unit (200) are connected by an external line (10), wherein the outlet valve (143,144) is provided as a normally open type solenoid valve used in low current ranges, normally maintains an open state to reduce heat generation, but closes when a closing signal is received, compared with a normally closed type solenoid valve which normally maintains a closed state, and wherein the control valve (150) is provided as a normally closed type solenoid valve which normally maintains a closed state to prevent the fluid pressure generated by the master cylinder (110) from flowing to the reservoir (115) when the integrated electro-hydraulic brake system is operating anomalously. System according to claim 1, wherein a simulation check valve (185) is further provided between the pedal simulator (180) and the simulation valve (186), an outlet pressure of the pedal simulator (180) is supplied by the simulation valve (186) only due to a pedal force of the brake pedal (30), and when the pedal force of the brake pedal (30) is released, oil is drawn in through the simulation check valve (185) and stored in the pedal simulator (180), and the simulation check valve (186) is connected to the reservoir (115) by an oil passage (189). System according to one of claims 1 or 2, wherein the external line (10) connects the accumulator (230) and a hydraulic pressure passage (120) which is connected to the inlet valve (141, 142), and a check valve (125) is installed in the hydraulic pressure passage (120) to prevent backflow of pressure. System according to one of claims 1 to 3, wherein the integrated hydraulic control device comprises a first and a second safety passage (171, 172) connecting the master cylinder (110) and the two hydraulic circuits (HC1, HC2) to control a brake fluid when the integrated electro-hydraulic brake system operates anomalously, and the shut-off valve comprises a first shut-off valve (173) installed and configured in the first safety passage (171) to control a connection with the master cylinder (110), and a second shut-off valve (174) installed and configured in the second safety passage (172) to control a connection with the master cylinder (110). System according to claim 4, wherein the first and second shut-off valves (173, 174) are provided as normally open solenoid valves which normally maintain an open state but are closed in a normal braking state. System according to any one of claims 1 to 5, wherein each of the hydraulic circuits (HC1, HC2) comprises: a normally open solenoid valve (161) arranged and configured upstream of the wheel cylinder (20) to control the supply of fluid pressure to the wheel cylinder (20); a normally closed solenoid valve (162) arranged and configured downstream of the wheel cylinder (20) to control the output of fluid pressure from the wheel cylinder (20); and a return passage (160) connecting the normally closed solenoid valve (162) and the reservoir (115), wherein the return passage (160) is connected to the simulation valve (186). System according to one of claims 1 to 6, wherein an impulse damper (135) configured to minimize pressure impulses is provided in an inlet passage (131) connecting the inlet valve (141, 142), the outlet valve (143, 144) and the two hydraulic circuits (HC1, HC2). System according to claim 7, wherein the inlet valve (141, 142) is provided as a normally closed solenoid valve which normally maintains a closed state.

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