Vehicle brake and method of controlling the same

Abstract

The present disclosure provides a vehicle brake and a control method thereof, the vehicle brake including a reservoir configured to store fluid therein, a hydraulic circuit configured to deliver hydraulic pressure to a wheel of a vehicle, a plurality of valves provided to regulate a flow of the fluid in the hydraulic circuit, and a master cylinder including a cylinder, a master piston movably disposed within the cylinder and having a pocket formed on one side of the master piston, and a center piston disposed within the cylinder and having a penetration hole formed in at least a portion of the center piston, wherein the penetration hole is formed to have a size smaller than a cross-sectional area of the pocket, and as the master piston moves, at least a portion of the center piston is inserted into the pocket and thus a pressurization area of the master piston is reduced.

Description

[0001] Cross-citation of related applications

[0002] This application claims priority and benefit to Korean Patent Application No. 10-2021-0153081, filed on November 9, 2021, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] This disclosure relates to a vehicle brake and a method for controlling the same. Background Technology

[0004] The content described in this article is for background information only and does not constitute prior art.

[0005] Electronic Stability Control (ESC) integrated braking system is a conventional braking system (CBS) that includes ESC and applies active braking to it. When the vehicle is in motion and its stability decreases, the ESC integrated braking system performs functions such as Anti-lock Braking System (ABS), Vehicle Dynamics Control (VDC), and Traction Control System (TCS) to ensure stability.

[0006] The ESC integrated braking system includes a master cylinder, pedal simulator, motor, screws, nuts, hydraulic circuit, and multiple valves. The master cylinder is the component that generates the hydraulic pressure required to brake the vehicle, and is classified into single-acting master cylinders and double-acting master cylinders based on the direction of the hydraulic pressure.

[0007] The double-acting master cylinder generates hydraulic pressure whenever the piston moves forward or backward. When the piston's direction of movement changes, the double-acting master cylinder needs time to generate hydraulic pressure behind the piston. Therefore, when emergency braking is required, the double-acting master cylinder suffers from reduced braking efficiency.

[0008] When using a single-acting master cylinder to solve this problem of a double-acting master cylinder, there is a problem of increasing the package size of the braking system because a master cylinder with a small cross-sectional area and a long length must be manufactured to generate a high pressure of about 200 bar. Summary of the Invention

[0009] This disclosure aims to provide a vehicle brake that can enhance braking efficiency during emergency braking by using a single-acting master cylinder including a piston, the pressure area of ​​which is altered.

[0010] This disclosure aims to provide a vehicle brake that allows for a reduction in the package size of the braking system by using a single-acting master cylinder comprising a piston, wherein the pressure area of ​​the piston is altered.

[0011] The objectives to be addressed in this disclosure are not limited to those described above, and other objectives not described above will be clearly understood by those skilled in the art through the following description.

[0012] According to at least one aspect, this disclosure provides a vehicle brake comprising: a reservoir configured to store fluid therein; a hydraulic circuit configured to transmit hydraulic pressure to the wheels of a vehicle; a plurality of valves configured to regulate the flow rate of the fluid in the hydraulic circuit; and a master cylinder including a cylinder body, a master piston, and a center piston, the master piston being movably disposed within the cylinder body and having a receptacle formed on one side thereof; the center piston being disposed within the cylinder body and having a through-hole formed in at least a portion thereof, wherein the through-hole is formed to have a cross-sectional area smaller than that of the receptacle, and as the master piston moves, at least a portion of the center piston is inserted into the receptacle, thereby reducing the pressurized area of ​​the master piston.

[0013] According to another aspect, this disclosure provides a method for controlling a vehicle brake, the vehicle brake including a master piston and a center piston, a housing formed on one side of the master piston, and a through hole formed in the center piston, the size of the through hole being smaller than the cross-sectional area of ​​the housing; the method includes: moving the master piston forward; determining whether the master piston has reached one end of the center piston; determining whether the vehicle wheel is in a slipping state; when it is determined that the vehicle wheel is in a slipping state, determining whether to activate the anti-lock braking system (ABS) function; and when it is determined that the ABS function is not activated, opening a first valve disposed between the through hole and a reservoir and moving the master piston forward again. Attached Figure Description

[0014] The above and other objects, features and advantages of this disclosure will become more apparent to those skilled in the art from the detailed description of exemplary embodiments of this disclosure with reference to the accompanying drawings, wherein:

[0015] Figure 1 This is a view showing the structure of the main cylinder according to an embodiment of the present disclosure;

[0016] Figure 2 This is a hydraulic circuit diagram of a vehicle brake according to an embodiment of the present disclosure;

[0017] Figure 3 This is a view illustrating the working principle of a low-pressure conventional braking system (CBS) for a vehicle brake according to an embodiment of the present disclosure;

[0018] Figure 4 This is a view illustrating the working principle of a high-pressure CBS in a vehicle brake according to an embodiment of the present disclosure;

[0019] Figure 5 This is a view illustrating the working principle of an anti-lock braking system (ABS) for a vehicle brake according to an embodiment of the present disclosure;

[0020] Figure 6This is a view illustrating the working principle of a vehicle brake when the hydraulic circuit leaks according to an embodiment of the present disclosure;

[0021] Figure 7 This is a view illustrating the working principle when standby braking is performed by a vehicle brake according to an embodiment of the present disclosure;

[0022] Figure 8 It is a graph showing the relationship between the displacement of the main piston of a vehicle brake according to an embodiment of the present disclosure and the current applied to the motor; and

[0023] Figure 9 This is a flowchart illustrating a method for controlling a vehicle brake according to an embodiment of the present disclosure. Detailed Implementation

[0024] In the following description, some exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the following description, although elements are shown in different drawings, the same reference numerals preferably denote the same elements. Furthermore, in the following description of some embodiments, for the purpose of clarity and brevity, detailed descriptions of known functions and configurations incorporated herein will be omitted.

[0025] Furthermore, terms such as first, second, A, B, (a), (b), etc., are used only to distinguish one component from another, and do not imply or suggest the substance, order, or sequence of the components. Throughout the specification, when a part "includes" or "comprises" a component, that part is intended to include other components, and such other components are not excluded unless specifically stated to the contrary. Terms such as "unit" or "module" refer to one or more units for performing at least one function or operation, which can be implemented by hardware, software, or a combination thereof.

[0026] Figure 1 This is a view showing the structure of the main cylinder according to an embodiment of the present disclosure.

[0027] Figure 2 This is a hydraulic circuit diagram illustrating a vehicle brake according to an embodiment of the present disclosure.

[0028] Reference Figure 1 and Figure 2 According to one embodiment of the present disclosure, a vehicle brake may include a master cylinder 100, a reservoir 210, a hydraulic circuit 220, a plurality of valves, a pedal simulator 260, and a control unit (not shown).

[0029] The master cylinder 100 may include a cylinder body 110, a master piston 120, a housing 122, a center piston 130, a through hole 132, a motor 140, a screw 150, a nut 160, and a sealing member 170.

[0030] Master cylinder 100 generates the hydraulic pressure required to brake the vehicle. Master cylinder 100 is connected to reservoir 210 and the vehicle's wheels FR, FL, RR, and RL. Master cylinder 100 can transmit hydraulic pressure to wheels FR, FL, RR, and RL using hydraulic circuit 220. Master cylinder 100 can operate in a single-acting mode.

[0031] The cylinder body 110 can be formed as a hollow cylinder. Brake oil required to generate hydraulic pressure flows into the cylinder body 110. The main piston 120, center piston 130, sealing member 170, etc. are disposed in the cylinder body 110. The cylinder body 110 is connected to the reservoir 210 and the wheels FR, FL, RR, and RL via a hydraulic circuit 220.

[0032] A main piston 120 is movably disposed within a cylinder body 110. A housing 122 is formed on one side of the main piston 120. The main piston 120 may be formed as a hollow cylinder. The main piston 120 is connected to a nut 160 and moves with the nut 160 as the nut 160 moves. The main piston 120 generates the hydraulic pressure required to brake the vehicle by moving in a direction from one end of the cylinder body 110 toward the other end (hereinafter referred to as forward movement). When the main piston 120 moves forward, a center piston 130 may be inserted into the housing 122. The housing 122 is formed to have a cross-sectional area larger than that of the through hole 132. When at least a portion of the center piston 130 is inserted into the housing 122, the pressurized area of ​​the main piston 120 decreases. At least one sealing member 170 may be disposed between the outer surface of the main piston 120 and the inner surface of the cylinder body 110.

[0033] A central piston 130 is disposed at the other end inside the cylinder block 110. The central piston 130 may be formed as a hollow cylinder. A through hole 132 is formed in at least a portion of the central piston 130. The through hole 132 is connected to a reservoir 210, and a first valve 231 is disposed between the through hole 132 and the reservoir 210. The through hole 132 is formed to have a cross-sectional area smaller than that of the reservoir 122. When the main piston 120 moves, the central piston 130 may be inserted into the reservoir 122. When the central piston 130 is inserted into the reservoir 122, the pressurization area of ​​the main piston 120 decreases. At least one sealing member 170 may be disposed on the outer surface of the central piston 130. The central piston 130 may be formed to have one of various lengths depending on the desired pressure required for braking the vehicle.

[0034] Motor 140 generates driving force. Motor 140 is connected to screw 150 and transmits driving force to screw 150. A position sensor (not shown) may be mounted on one side of motor 140. The position sensor detects the displacement of main piston 120.

[0035] Screw 150 is attached to one side of motor 140. Screw 150 rotates using the driving force transmitted from motor 140. Screw 150 is attached to nut 160. Screw 150 may be a ball screw.

[0036] Nut 160 is connected to screw 150. Nut 160 moves along the longitudinal direction of screw 150 as screw 150 rotates. Nut 160 is connected to main piston 120 to move main piston 120.

[0037] A sealing member 170 may be disposed between the outer surface of the main piston 120 and the inner surface of the cylinder 110. A sealing member 170 may also be disposed on the outer surface of the center piston 130. The sealing member 170 may be configured to allow unidirectional fluid flow. Multiple sealing members 170 may be provided and formed in a "V" shape.

[0038] The reservoir 210 is configured to store fluids such as brake fluid. The reservoir 210 is connected to all wheels FR, FL, RR, and RL, pedal simulator 260, cylinder block 110, and through hole 132 via hydraulic circuit 220.

[0039] Hydraulic circuit 220 is configured to transmit hydraulic pressure generated by master cylinder 100 and / or pedal simulator 260 to wheels FR, FL, RR, and RL. According to one embodiment, hydraulic circuit 220 connects to components of the vehicle brake system. Multiple valves configured to regulate fluid flow are disposed in hydraulic circuit 220. At least one pressure sensor may be disposed in hydraulic circuit 220.

[0040] The first valve 231 is disposed between the through hole 132 and the reservoir 210. With at least a portion of the central piston 130 inserted into the seat 122, the pressurized area of ​​the main piston 120 decreases when the first valve 231 is opened.

[0041] The second valve 232 is located inside the cylinder body 110 between the reservoir 210 and the cylinder block 110. When the master piston 120 moves backward, the second valve 232 opens, allowing brake fluid to flow smoothly into the cylinder body 110.

[0042] The pedal simulator 260 is a component that provides pedal feel to the driver of a vehicle and is connected to the reservoir 210 and wheels FR, FL, RR, and RL. The pedal simulator 260 may include a brake pedal, pressure sensors, etc.

[0043] In a vehicle brake according to one embodiment of the present disclosure, when the master piston 120 moves forward, at least a portion of the center piston 130 is inserted into the housing 122. A through-hole 132 with a cross-sectional area smaller than that of the housing 122 is formed in the center piston 130. With the center piston 130 inserted into the housing 122, when the first valve 231 opens and the master piston 120 moves forward, the pressure area of ​​the master piston 120 decreases. Therefore, braking efficiency during emergency braking can be improved, and the package size of the braking system can be reduced by using a master cylinder 100 that operates in a single-acting manner.

[0044] Figure 3 This is a view illustrating the working principle of a low-pressure conventional braking system (CBS) for a vehicle brake according to an embodiment of the present disclosure.

[0045] Figure 4 This is a view illustrating the working principle of a high-pressure CBS in a vehicle brake according to an embodiment of the present disclosure.

[0046] Reference Figure 3 and Figure 4 In low-pressure CBS operation, the control unit closes the first valve 231 and moves the master piston 120 forward to generate the hydraulic pressure required to brake the vehicle. As the master piston 120 moves forward, hydraulic pressure is generated in the cylinder 110. The hydraulic pressure generated in the cylinder 110 is transmitted to the vehicle's wheels FR, FL, RR, and RL via hydraulic circuit 220. The control unit uses a position sensor to determine the displacement of the master piston 120. According to one embodiment, the vehicle brake can be designed to generate a desired pressure in the hydraulic circuit 220 when the master piston 120 reaches one end of the center piston 130. In this case, one end of the center piston 130 is the end of the center piston 130 that inserts into the housing 122. The desired pressure is either the hydraulic pressure required to brake the vehicle or the pressure set to perform the anti-lock braking system (ABS) function.

[0047] In high-pressure CBS operation, the control unit closes the first valve 231 and moves the main piston 120 forward. The control unit uses a position sensor to determine the displacement of the main piston 120. When the pressure generated in the hydraulic circuit 220 is lower than the desired pressure, even if the main piston 120 reaches one side of the center piston 130, the control unit still opens the first valve 231 and moves the main piston 120 forward again. As the pressurized area of ​​the main piston 120 decreases and the main piston 120 moves forward, a pressure higher than the desired pressure can be generated in the hydraulic circuit 220.

[0048] Figure 5 This is a view illustrating the working principle of an ABS (Anti-lock Braking System) in a vehicle brake according to an embodiment of the present disclosure.

[0049] Reference Figure 5 The working principle of ABS in a vehicle brake according to one embodiment is described.

[0050] When the vehicle's ABS function is activated, the control unit determines the displacement of the master piston 120. When the master piston 120 has moved forward to its maximum displacement, the control unit uses inlet valves 241, 242, 243, and 244, and outlet valves 251, 252, 253, and 254 to control the hydraulic pressure generated at wheels FR, FL, RR, and RL. The control unit moves the master piston 120 backward, allowing brake fluid to flow into cylinder 110. The control unit then moves the master piston 120 forward again to generate hydraulic pressure in cylinder 110.

[0051] When the ABS function is activated, the control unit determines the condition of the ground surface on which the vehicle is traveling. The control unit can determine the ground condition using the pressure required to control the FR, FL, RR, and RL wheels (hereinafter, "wheel control pressure"). The control unit compares the wheel control pressure with a preset pressure. When the wheel control pressure is lower than the preset pressure, the control unit determines that the ground is in a low-friction state. When the control unit determines that the ground is in a low-friction state, the control unit controls the master piston 120 to move rearward by a maximum displacement and then forward again. When the wheel control pressure is higher than the preset pressure, the control unit determines that the ground is in a high-friction state. When the control unit determines that the ground is in a high-friction state, the control unit moves the master piston 120 rearward to one side of the center piston 130 and then forward again.

[0052] Figure 6 This is a view illustrating the working principle of a vehicle brake when the hydraulic circuit leaks according to an embodiment of the present disclosure.

[0053] Reference Figure 6 When the control unit determines that there is a brake fluid leak in the hydraulic circuit 220 on the rear wheel side, the control unit opens the front wheel valve 233 and closes the rear wheel valve 234. The control unit moves the master piston 120 forward to provide hydraulic pressure to the front wheel FR and the front wheel FL, thereby braking the vehicle.

[0054] Figure 7 This is a view illustrating the working principle when standby braking is performed by a vehicle brake according to an embodiment of the present disclosure.

[0055] Reference Figure 7When the vehicle's backup braking is applied, the control unit closes the first valve 231, the front wheel valve 233, and the rear wheel valve 234, and closes the front wheel backup valve 235 and the rear wheel backup valve 236. The control unit transmits the hydraulic pressure generated by the pedal simulator 260 to the wheels FR, FL, RR, and RL to brake the vehicle.

[0056] Figure 8 This is a graph showing the relationship between the displacement of the main piston of a vehicle brake according to an embodiment of the present disclosure and the current applied to the motor.

[0057] Reference Figure 8 As the main piston 120 moves forward, the current applied to the motor 140 and the pressure generated in the cylinder 110 increase. When the main piston 120 reaches one side end of the center piston 130 (piston displacement = x), the pressure-applying area of ​​the main piston 120 decreases when the first valve 231 opens. As the pressure-applying area of ​​the main piston 120 decreases, the force required to generate the same pressure decreases, thus reducing the current applied to the motor 140. When the main piston 120 moves forward again, the current applied to the motor 140 and the pressure generated in the cylinder 110 increase. Therefore, a vehicle brake according to an embodiment of this disclosure has the effect of generating high pressure using low current.

[0058] Figure 9 This is a flowchart illustrating a method for controlling a vehicle brake according to an embodiment of the present disclosure.

[0059] The control unit moves the master piston forward to generate the hydraulic pressure required to brake the vehicle (S910).

[0060] The control unit determines whether the main piston has reached one side of the center piston (S920). The control unit uses a position sensor installed in the motor 140 to determine the displacement of the main piston 120. Whether the main piston 120 has reached one side of the center piston 130 can be determined based on the displacement of the main piston 120.

[0061] When the control unit determines that the master piston has reached one side of the center piston, the control unit determines whether the vehicle's wheels are in a slipping state (S930). The control unit can determine whether the wheels FR, FL, RR, and RL are in a slipping state based on whether the vehicle's wheels FR, FL, RR, and RL are rotating and whether the vehicle is moving.

[0062] When the control unit determines that the vehicle's wheels are slipping, it determines whether the vehicle's ABS function has been activated (S940). The control unit can determine whether the ABS function has been activated by comparing the pressure generated in the hydraulic circuit 220 with the pressure set to activate the ABS function.

[0063] When the control unit determines that the vehicle's ABS function is not activated, the control unit opens the first valve (S950). When the first valve 231 is open, the pressurization area of ​​the main piston 120 decreases.

[0064] The control unit moves the master piston forward to activate the ABS function (S960). With the first valve 231 open, when the master piston 120 moves forward, a pressure higher than the pressure set for activating the ABS function is generated in the hydraulic circuit 220, and the vehicle's ABS function is activated.

[0065] When the control unit determines that the vehicle's ABS function is activated, it determines the state of the ground on which the vehicle is traveling (S970). The control unit can use wheel control pressure to determine the ground state. The control unit compares the wheel control pressure with a preset pressure. When the wheel control pressure is lower than the preset pressure, the control unit determines that the ground is in a low-friction state; when the wheel control pressure is higher than or equal to the preset pressure, the control unit determines that the ground is in a high-friction state.

[0066] When the control unit determines that the ground is in a low-friction state, the control unit moves the main piston backward by the maximum displacement (S982). When the control unit determines that the ground is in a low-friction state, the control unit moves the main piston backward by the maximum displacement 120 to transmit higher hydraulic pressure to the wheels.

[0067] When the control unit determines that the ground is in a high-friction state, the control unit moves the main piston to one side of the center piston (S984). When the ground is in a high-friction state, the control unit moves the main piston 120 backward to one side of the center piston 130 in order to quickly transmit hydraulic pressure to the wheels.

[0068] The control unit moves the master piston forward again (S990). When the ABS function is activated, the control unit moves the master piston forward 120 to continuously supply hydraulic pressure to the vehicle's wheels.

[0069] According to one embodiment, since the vehicle brake uses a single-acting master cylinder that includes a piston with a changed pressure area, there is an effect of enhanced braking efficiency during emergency braking.

[0070] According to one embodiment, since the vehicle brake uses a single-acting master cylinder that includes a piston with a changed pressure area, there is an effect of reducing the package size of the braking system.

[0071] In the flowcharts of this disclosure, operations are performed sequentially, but this is merely an example to describe the technical spirit of one embodiment of this disclosure. In other words, since those skilled in the art, including one embodiment of this disclosure, can make various changes, modifications, and applications to this disclosure by altering the operations described in the flowcharts and performing the altered operations, without departing from the basic characteristics of the embodiments of this disclosure or performing one or more operations in parallel, the flowcharts are not limited to a chronological order.

[0072] While exemplary embodiments of this disclosure have been described for illustrative purposes, those skilled in the art will understand that various modifications, additions, and substitutions are possible without departing from the spirit and scope of the claimed invention. Therefore, exemplary embodiments of this disclosure have been described for the sake of brevity and clarity. The scope of the technical concept of these embodiments is not limited by the illustrations. Therefore, those skilled in the art will understand that the scope of the claimed invention is not limited to the embodiments explicitly described above, but rather by the claims and their equivalents.

Claims

1. A vehicle brake, comprising: A reservoir, configured to store fluid; A hydraulic circuit is configured to transmit hydraulic pressure to the wheels of a vehicle; Multiple valves are configured to regulate the flow rate of the fluid in the hydraulic circuit; as well as Master cylinder, including: Cylinder block; A main piston, configured to move in a forward or rearward direction, and including a first end portion movable within the cylinder when the main piston moves in the forward or rearward direction; and A central piston is disposed within the cylinder body and has a through-hole. The master cylinder has a receiving seat at the first end of the master piston, and the receiving seat includes an opening facing the central piston and a recessed space adjacent to the opening. Wherein, the size of the penetrating hole is smaller than the cross-sectional area of ​​the receiving seat, and The master cylinder is configured such that when the master piston moves in the rearward direction, the center piston is fully ejected from the recessed space of the receiver of the master piston via the opening, and when the master piston moves in the forward direction, the center piston is at least partially inserted into the receiver via the opening.

2. The vehicle brake according to claim 1, wherein, The master cylinder also includes: A motor is coupled to the second end of the main piston and configured to generate driving force; A screw, connected to the motor, and configured to rotate when driven by the driving force; and A nut, connected to the screw, is arranged to move in the longitudinal direction of the screw as the screw rotates. The main piston is arranged to move when the nut moves.

3. The vehicle brake according to claim 2, wherein, The master cylinder also includes a position sensor coupled to the motor.

4. The vehicle brake according to claim 1, wherein, The reservoir is connected to the interior of the cylinder and the through hole.

5. The vehicle brake according to claim 4, wherein, The plurality of valves includes a valve positioned between the through-hole and the reservoir.

6. The vehicle brake according to claim 4, wherein, The plurality of valves includes a valve located between the interior of the cylinder and the reservoir.

7. The vehicle brake of claim 1 further includes a pedal simulator configured to provide pedal feel to the driver of the vehicle.

8. The vehicle brake according to claim 1, wherein, The master cylinder is configured to operate in a single-acting mode.

9. The vehicle brake according to claim 1, wherein: The main cylinder also includes multiple sealing components, some of which are positioned between the inner surface of the cylinder body and the outer surface of the main piston, while the remaining sealing components are positioned on the outer surface of the central piston; and The plurality of sealing components are configured to transfer the fluid in one direction.

10. A method for controlling a vehicle brake, the vehicle brake comprising: (a) A main piston, wherein a receiving seat is positioned on one side of the main piston; (b) a central piston having a through hole with a size smaller than the cross-sectional area of ​​the receptacle, the method comprising: Move the main piston forward; Determine whether the main piston has reached the center piston; Determine if the vehicle's wheels are slipping; In response to determining that the wheels of the vehicle are in the slipping state, it is determined whether the anti-lock braking system (ABS) function is being activated; and In response to determining that the ABS function is not executed, perform: Open the first valve positioned between the through-hole and the reservoir; and The main piston is moved forward again.

11. The method of claim 10, further comprising: In response to determining that the ABS function is being performed, the state of the ground on which the vehicle is traveling is determined; In response to determining that the ground is in a low-friction state, the main piston is moved backward by a maximum displacement, and then the main piston is moved forward again; or In response to determining that the ground is in a high-friction state, the main piston is moved backward to the center piston; and the main piston is moved forward again.

Images