Braking system for a vehicle capable of regenerative braking and hydraulic braking and control method thereof

Abstract

The present invention provides a braking system for a vehicle capable of regenerative braking and hydraulic braking and a control method thereof. A braking system is configured to perform one or more of cooperative braking or a combination of regenerative braking and hydraulic braking. The system includes: a master cylinder; a reaction disc made of an elastic material and configured to compress the master cylinder; a rod assembly, the rod assembly including an operating rod, an elastomer fixing unit, and an elastomer, one end of the elastomer abutting a portion of the operating rod and the other end abutting the elastomer fixing unit; an electric booster including a motor piston, the motor piston being configured to compress at least a portion of the reaction disc to compress the master cylinder by adjusting the displacement of the motor piston; and an electric controller configured to control the electric booster and perform control to brake the vehicle by using one or more of the regenerative braking and the hydraulic braking.

Description

Technical Field

[0001] The present disclosure relates to a braking system of a vehicle capable of regenerative braking and hydraulic braking and a control method thereof. Background Art

[0002] The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

[0003] Regenerative braking is a braking method that uses the vehicle's running inertia to drive the motor as a generator and uses the resistance generated by the drive motor as braking force.

[0004] In the case of a hybrid electric vehicle (HEV), a regenerative brake unit and a hydraulic brake unit cooperate to brake the vehicle (hereinafter referred to as "cooperative braking"), thereby providing a stable braking force to the vehicle.

[0005] The vehicle also includes an electric booster unit to amplify the driver's pedal effort. The electric booster unit uses the rotational torque of an electric motor housed within the unit to increase the force applied from the operating lever to the interior of the master cylinder. Furthermore, the electric booster unit is configured to provide the driver with the desired pedal feel. Specifically, the electric booster unit is configured to generate an appropriate amount of pedal force corresponding to the pedal stroke when the reaction plate is compressed by the electric booster unit.

[0006] Meanwhile, when vehicles with conventional cooperative braking perform regenerative braking, electronic stability control (ESC) is used to reduce the hydraulic pressure during regenerative braking by an amount compensated by the regenerative braking. To achieve this, conventional vehicles require an ESC with specifications that can coordinate the control of regenerative braking and hydraulic braking. Specifically, ESC requires a pressure-reducing device, such as an accumulator, to reduce the hydraulic pressure, which places higher requirements on the ESC specifications and can lead to increased costs.

[0007] Furthermore, when regenerative braking is disabled during cooperative braking in vehicles with conventional cooperative braking, ESC is used to increase the amount of hydraulic fluid in the brake system to enhance the braking force of the hydraulic brakes. A pump is activated to draw fluid from the master cylinder to increase the amount of hydraulic fluid in the brake system. As a result, the pressure generated within the master cylinder decreases, and the driver experiences an unnatural sensation of reduced pedaling force.

[0008] Meanwhile, in vehicles equipped with conventional regenerative braking units and hydraulic brake units, pedal force is generated solely by the pedal spring during regenerative braking. Therefore, when the available regenerative braking period is long, the driver may feel a disconnect in pedal force, leading to a deterioration in sensitivity.

[0009] Furthermore, conventional vehicles employ an electronic stability control (ESC) system for regenerative braking, which hydraulically reduces the amount of brake compensation associated with regenerative braking. This requires an ESC with specifications that can coordinate regenerative braking and hydraulic braking. Specifically, the ESC requires a pressure reducer, such as an accumulator, to reduce the hydraulic pressure, increasing the ESC's specifications. This, in turn, increases manufacturing costs. Summary of the Invention

[0010] In view of the above circumstances, a main object of the present disclosure is to reduce the regenerative braking force by receiving a regenerative braking interruption signal and eliminate an unnatural pedaling feeling generated when the hydraulic braking force increases by an amount equal to the reduction in the regenerative braking force.

[0011] Problems to be solved by the present disclosure are not limited to the above-mentioned problems, and other problems not mentioned herein can be clearly understood by those skilled in the art through the following description.

[0012] According to one aspect of the present application, a braking system is configured to perform one or more of cooperative braking or a combination of regenerative braking and hydraulic braking when braking a vehicle, the braking system comprising: a master cylinder; a reaction disc, the reaction disc being made of an elastic material and configured to compress the master cylinder; a rod assembly, the rod assembly comprising an operating rod, an elastomer fixing unit, and an elastomer, the displacement of the operating rod being adjusted based on the amount of force applied to the brake pedal, one end of the elastomer abutting a portion of the operating rod and the other end abutting the elastomer fixing unit; an electric booster, the electric booster comprising a motor piston configured to compress at least a portion of the reaction disc to compress the master cylinder by adjusting the displacement of the motor piston; and an electric controller, the electric controller being configured to control the electric booster and perform control to brake the vehicle by using one or more of the regenerative braking and the hydraulic braking.

[0013] If the electric controller brakes the vehicle by performing at least the regenerative braking among the regenerative braking and the hydraulic braking, the electric controller may drive the electric booster so as to compress the reaction plate when the regenerative braking is disabled.

[0014] The operating rod may be configured to compress a central portion of the reaction plate, and the motor piston may be configured to compress an outer periphery of the reaction plate.

[0015] If the motor piston compresses the reaction plate, the central portion of the reaction plate may protrude toward the operating rod according to the degree of compression, thereby forming a protruding portion.

[0016] When the protrusion abuts the operating rod as the brake pedal is pressed, the pressure applied from the reaction plate to the operating rod may increase as the pressure applied by the motor piston on the reaction plate increases, and at the same time the contact area between the reaction plate and the operating rod may decrease.

[0017] When the hydraulic pressure in the master cylinder is maintained, if the motor piston moves further toward the reaction plate than the operating rod and the displacement of the motor piston and the displacement of the operating rod are equal, the amount of pedal force can be maintained regardless of how much the master cylinder is compressed by the reaction plate.

[0018] Among the spring and the damper, the elastic body may include at least the spring.

[0019] According to one aspect of the present application, a method for controlling a braking system, wherein the braking system is configured to perform one or more of cooperative braking and a combination of regenerative braking and hydraulic braking when braking a vehicle, the method comprising the following steps: (a) calculating the total braking force required to brake the vehicle based on the stroke of the pedal measured by a pedal travel sensor when a pedal is depressed; (b) calculating the required regenerative braking force based on the required total braking force; (c) driving a regenerative braking unit to provide braking force according to the required regenerative braking force; (d) determining whether to stop the regenerative braking; (e) if it is determined that the regenerative braking needs to be stopped, calculating the required hydraulic braking force corresponding to stopping the regenerative braking; (f) calculating the required displacement of a motor piston corresponding to the required hydraulic braking force; and (g) driving an electric booster to compress a reaction plate by moving the motor piston according to the required displacement.

[0020] The motor piston may be made of an elastic material.

[0021] The motor piston may be configured to compress an outer circumference of the reaction plate.

[0022] In step (g), when the motor piston is allowed to compress the reaction plate, the amount of reaction force developed is constant.

[0023] In step (f), the required displacement may be calculated based on whether the reaction plate abuts an operating lever, the displacement of the operating lever being adjusted based on the amount of force applied to the brake pedal.

[0024] As described above, according to the present embodiment, a braking system and a control method thereof for a vehicle capable of regenerative braking and hydraulic braking are provided by using an elastomer fixed at one end and providing a pedal feel to the driver, and a reaction plate of an elastic material, so as to prevent the driver from having an unnatural pedaling feeling when the regenerative braking force is reduced and the hydraulic braking force is increased while the total braking force remains unchanged.

[0025] An object of the present disclosure is to provide a braking system having improved sensitivity qualities in regenerative braking and a method of controlling the braking system.

[0026] Furthermore, an object of the present disclosure is to provide a brake system and a method of controlling the brake system, which can be equipped with an ESC having ordinary specifications and is not limited by a maximum boost ratio of an electric booster unit.

[0027] According to the second embodiment of the present disclosure, when regenerative braking is performed, pedal disconnection is reduced and sensitivity quality is improved because the pedal force is adjusted using the pedal spring and the damper.

[0028] Furthermore, when regenerative braking is performed, the hydraulic pressure is adjusted by the electric booster unit to correspond to the braking compensation amount of the regenerative braking. Therefore, since a general ECS can be applied to a vehicle without a dedicated ESC, the manufacturing cost of the vehicle is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a cross-sectional view of a brake system according to an embodiment of the present disclosure;

[0030] Figure 2A and Figure 2B This is a schematic diagram used to illustrate the relationship between the elastic material reaction plate, operating rod, motor piston and pedal force;

[0031] Figure 3 is a graph for illustrating the relationship between the total pedal force, the pedal force of the elastic body, the pedal force of the reaction plate, the regenerative braking force, and the hydraulic braking force with respect to time when the electric control unit alone performs regenerative braking if regenerative braking is disabled during braking;

[0032] Figures 4A to 4C Is used to illustrate Figure 3 Starting point, time t 13 and time t 14 A schematic diagram of how the operation is performed;

[0033] Figure 5 is a graph illustrating the relationship between the total pedal force, the pedal force of the elastic body, the pedal force of the reaction plate, the regenerative braking force, and the hydraulic braking force with respect to time if the amount of pedal effort increases while regenerative braking is disabled during braking when the electric control unit alone performs regenerative braking;

[0034] Figures 6A to 6C Is used to illustrate Figure 5 Starting point, time t 23 and time t 24A schematic diagram of how the operation is performed;

[0035] Figure 7 is a graph for illustrating the relationship between the total pedal force, the pedal force of the elastic body, the pedal force of the reaction plate, the regenerative braking force, and the hydraulic braking force with respect to time when the electric control unit performs regenerative braking and hydraulic braking if regenerative braking is disabled during braking;

[0036] Figures 8A to 8C Is used to illustrate Figure 7 Starting point, time t 34 and time t 35 A schematic diagram of how the operation is performed;

[0037] Figure 9 is a graph illustrating the relationship between the total pedal force, the pedal force of the elastic body, the pedal force of the reaction plate, the regenerative braking force, and the hydraulic braking force with respect to time if the amount of pedal effort increases while regenerative braking is disabled during braking when the electric control unit alone performs regenerative braking;

[0038] 10A to 10C Is used to illustrate Figure 9 Starting point, time t 44 and time t 45 A schematic diagram of how the operation is performed;

[0039] Figure 11 is a flowchart of a method for controlling a braking system according to an embodiment of the present disclosure;

[0040] Figure 12 is a conceptual diagram showing an initial state of a brake system according to a second embodiment of the present disclosure;

[0041] Figure 13 is a conceptual diagram illustrating a dead stroke state of a brake system according to a second embodiment of the present disclosure;

[0042] Figure 14A is a conceptual diagram illustrating a first regenerative braking mode state of a brake system according to a second embodiment of the present disclosure;

[0043] Figure 14B is a conceptual diagram showing a state when a second regenerative braking mode of a brake system according to a second embodiment of the present disclosure is started;

[0044] Figure 14C is a conceptual diagram showing a state after the second regenerative braking mode of the brake system according to the second embodiment of the present disclosure is started;

[0045] Figure 15is a graph showing a relationship between a pedal stroke and a pedal force in each period in a regenerative braking mode of a brake system according to a second embodiment of the present disclosure;

[0046] Figure 16A is a conceptual diagram showing a first hydraulic braking mode state of a braking system according to a second embodiment of the present disclosure;

[0047] Figure 16B is a conceptual diagram showing a state when a second hydraulic braking mode of a brake system according to a second embodiment of the present disclosure is started;

[0048] Figure 16C is a conceptual diagram showing a state after the second hydraulic braking mode of the brake system according to the second embodiment of the present disclosure is started;

[0049] Figure 17 is a graph showing the relationship between the pedal stroke and the pedal force in each period in the hydraulic braking mode of the brake system according to the second embodiment of the present disclosure;

[0050] Figure 18 is a flowchart illustrating a method of controlling a braking system according to a second embodiment of the present disclosure;

[0051] Figure 19 is a flowchart showing a control method in a second regenerative braking mode state of a brake system according to a second embodiment of the present disclosure;

[0052] Figure 20 is a cross-sectional view of a brake system according to a third embodiment of the present disclosure;

[0053] Figure 21A and Figure 21B is a schematic diagram illustrating the relationship between the elastic reaction plate, the operating rod, the motor piston, and the pedal force;

[0054] Figure 22 is a graph illustrating a relationship between a total pedal force, a pedal force of an elastic body, a pedal force of a reaction plate, a regenerative braking force, and a hydraulic braking force changing with time when the control unit stops regenerative braking in a case where only regenerative braking is performed during braking;

[0055] Figures 23A to 23C This is an example Figure 22 The starting point and time point t 13 and t 14 Schematic diagram of the operation at;

[0056] Figure 24is a graph illustrating the relationship between the total pedal force, the pedal force of the elastic body, the pedal force of the reaction plate, the regenerative braking force, and the hydraulic braking force as a function of time when the pedaling amount increases while the control unit stops regenerative braking in a case where only regenerative braking is performed during braking;

[0057] Figures 25A to 25C This is an example Figure 24 The starting point and time point t 23 and t 24 Schematic diagram of the operation at;

[0058] Figure 26 is a graph illustrating a relationship between a total pedal force, a pedal force of an elastic body, a pedal force of a reaction plate, a regenerative braking force, and a hydraulic braking force over time when regenerative braking is stopped in a case where the control unit performs regenerative braking and hydraulic braking during braking;

[0059] Figures 27A to 27C This is an example Figure 26 The starting point, t 34 and t 35 Schematic diagram of the operation at;

[0060] Figure 28 is a graph illustrating a relationship between total pedal force, pedal force of the elastic body, pedal force of the reaction plate, regenerative braking force, and hydraulic braking force over time when the pedaling amount increases while regenerative braking is stopped in a case where the control unit performs both regenerative braking and hydraulic braking during braking;

[0061] Figures 29A to 29C This is an example Figure 28 The starting point, t 44 and t 45 a schematic diagram of the operation at ; and

[0062] Figure 30 is a flowchart of a method of controlling a brake system according to a third embodiment of the present disclosure. DETAILED DESCRIPTION

[0063] Figure 1 is a cross-sectional view of a brake system according to an embodiment of the present disclosure.

[0064] Reference Figure 1 The rod assembly 60 includes an operating rod 12 , an elastic body 17 and an elastic body fixing portion 16 .

[0065] The operating rod 12 is a medium that transmits the driver's pedal force to the reaction plate 420. One end of the operating rod 12 is connected to the pedal 11. The operating rod 12 can compress the master cylinder 14 by pushing the reaction plate 420 and the motor piston 28 toward the master cylinder 14. In the initial state when the pedal 11 is depressed, the other end of the operating rod 12 can be separated from the reaction plate 420. As the pedal 11 is depressed, the other end of the operating rod 12 moves forward toward the reaction plate 420.

[0066] The elastomer 17 is arranged so that one end abuts the operating rod 12 and the other end abuts the elastomer fixing portion 16. The elastomer 17 generates an elastic force as the operating rod 12 moves. Specifically, when the driver steps on the pedal 11, the operating rod 12 moves toward the reaction plate 420 and compresses the elastomer 17. The compressed elastomer 17 generates a reaction force called elastic force and provides the driver with a pedal feel. Since the other end of the elastomer 17 is arranged to abut the elastomer fixing portion 16, the elastomer 17 is only affected by the displacement of the operating rod 12. Even if no reaction force is generated from the reaction plate 420 because the operating rod 12 does not abut against the reaction plate 420, the driver can still have a pedal feel of the reaction force from the elastomer 17. In addition, since the elastomer 17 is connected to the elastomer fixing portion 16, rather than a part like the motor piston 28, even when this pressure changes, the driver will not have an unnatural pedaling feeling due to the pressure change in the master cylinder 14.

[0067] The elastic body 17 may include a spring or a combination of a spring 171 and a damper 172. In the present disclosure, the spring 171 and the damper 172 are shown as being connected in series, but are not limited thereto, and the spring 171 and the damper 172 may be connected in parallel.

[0068] The elastic body fixing portion 16 is fixed to the housing 30, and at least a portion of the elastic body 17 is attached to one side of the elastic body fixing portion 16. The elastic body fixing portion 16 is formed to support the elastic body 17 when the elastic body 17 is compressed by the driver's pedal force.

[0069] When the electric control unit 50 performs hydraulic braking, the disc unit 42 supplies hydraulic pressure to a plurality of wheel brakes (not shown) by compressing the master cylinder 14. The disc unit 42 includes a reaction disc 420 and a reaction disc reservoir 422.

[0070] The reaction plate 420 is configured to be compressed by one or more of the operating rod 12 and the motor piston 28. Figure 1 The reaction plate 420 and the motor piston 28 are shown in contact with each other. However, if the electric control unit 50 does not generate a brake request signal, this may mean that the motor piston 28 is separated from the reaction plate 420.

[0071] Reaction disc 420 can be constructed in such a manner that its outer circumference (i.e., its periphery) is compressed by motor piston 28, and its central portion is compressed by operating rod 12. To this end, the longitudinal cross-section of motor piston 28 can be approximately annular, and operating rod 12 can pass through a hollow portion formed in the center of motor piston 28. In this case, operating rod 12 and reaction disc 420 are coaxially arranged. However, the present disclosure is not limited thereto, and any brake system having a device capable of compressing reaction disc 420 by depressing pedal 11 and driving motor 22 can be included in the present disclosure.

[0072] Reaction plate 420 is made of a compressible elastic material. For example, at least a portion of reaction plate 420 may be made of a rubber material. When reaction plate 420 is compressed by one or more of operating lever 12 and motor piston 28, the reaction force generated by the compression force is transmitted to the driver through operating lever 12 and constitutes part of the pedal feel experienced by the driver.

[0073] Reaction disc receptacle 422 is formed such that a space formed therein accommodates at least a portion of reaction disc 420. When one side of reaction disc receptacle 422 is compressed by one or more of operating rod 12 and motor piston 28, the other side of reaction disc receptacle 422 compresses push rod 13.

[0074] The total pedal force provided to the driver may be determined as the sum of the pedal force generated by the reaction force to the compression force of the reaction plate 420 and the pedal force generated by the reaction force to the compression force of the elastic body 17 .

[0075] The electric control unit 50 generates a brake request signal based on a pedal signal transmitted from a pedal stroke sensor (not shown). The brake request signal is an electrical signal that allows at least part of a plurality of wheel brakes (not shown) to generate a braking force.

[0076] The electric control unit 50 calculates the total braking force required to brake the vehicle based on the pedaling signal. Furthermore, the electric control unit 50 determines whether to use regenerative braking, hydraulic braking, or both. Depending on whether regenerative braking and / or hydraulic braking are used, the regenerative braking force is applied and the electric booster unit 20 is controlled differently. The total braking force required can be the sum of the hydraulic braking force and the regenerative braking force. Multiple braking modes can be configured. For example, the electric control unit 50 can brake the vehicle by configuring a hydraulic braking mode that uses hydraulic braking force alone, a regenerative braking mode that uses regenerative braking force alone, and a coordinated braking mode that uses both hydraulic and regenerative braking forces.

[0077] Figure 2A and Figure 2BThis diagram illustrates the relationship between the elastic reaction plate, operating rod, motor piston, and pedal force.

[0078] Figure 2A A schematic diagram for explaining the pedal force with respect to the displacement of the operating rod 12 when the displacement of the reaction plate 420 does not change is depicted. Figure 2B A schematic diagram for explaining the amount of pedal force relative to the force applied to the master cylinder 14 when the relative displacement of the motor piston 28 and the operating rod 12 is constant is depicted.

[0079] Reference Figure 2A , it can be seen that the pedal force increases when operating lever 12 moves toward reaction plate 420, while the pedal force decreases when operating lever 12 moves in the opposite direction. However, if the difference between the displacement of operating lever 12 and the displacement of reaction plate 420 is within a given range, the driver's pedal feel remains almost unchanged. This is attributed to the elastic material properties of reaction plate 420.

[0080] Reference Figure 2B If the difference between the displacement of the operating rod 12 and the displacement of the reaction plate 420 is constant and the hydraulic pressure in the master cylinder 14 is increased by compressing the reaction plate 420, the driver's pedal feel increases with the hydraulic pressure in the master cylinder 14, regardless of the displacement of the motor piston 28 and the displacement of the operating rod 12.

[0081] Figure 3 It is a graph for explaining the relationship between the total pedal force, the pedal force of the elastic body, the pedal force of the reaction plate, the regenerative braking force and the hydraulic braking force with respect to time when the electric control unit performs regenerative braking alone and the regenerative braking is disabled during braking. Figures 4A to 4C Is used to illustrate Figure 3 Starting point, time t 13 and time t 14 A diagram showing how the operation is performed.

[0082] In the following, Figure 3 、 Figure 5 、 Figure 7 and Figure 9 , L1 represents the total pedal force, L2 represents the pedal force of the elastic body 17, L3 represents the pedal force of the reaction plate 420, L4 represents the regenerative braking force, and L5 represents the hydraulic braking force.

[0083] Figure 4A Depicted in Figure 3 The operation at the starting point, Figure 4B Depicts Figure 3 Time t 13 The operation at Figure 4C Depicts Figure 3 Time t 14Operation at.

[0084] Figure 3 The starting point is the time point r when the driver starts to step on the pedal 11 11 At this point in time, a total pedal force L1 is generated. Since the operating rod 12 is separated from the central portion 423 of the reaction plate 420, the pedal force L3 caused by the reaction force of the reaction plate 420 is not generated.

[0085] At the starting point and as the time t for the initial duration of the driver's depression of the pedal 11 11 During this period, the pedal force L2 generated by the compression of the elastic body 17 gradually increases.

[0086] Time t 11 and time t 12 The period in between is a period during which the corresponding braking force is generated as the amount of force applied to the pedal 11 by the driver increases. Figure 3 It is illustrated that the electric control unit 50 activates the regenerative braking mode to brake the vehicle during this period, during which the hydraulic braking force L5 is not generated but the regenerative braking force L4 gradually increases.

[0087] Time t 12 and time t 13 The period between is the period during which the amount of force applied by the driver to the pedal 11 is maintained. During this period, the amount of braking force required by the driver does not change, so the regenerative braking force L4 is also maintained constant. Figure 4B As shown, the motor piston 28 is at time t 13 Compressing the reaction disk 420 causes the displacement of the disk unit 42 to be as Figure 4B As shown from d 11 Move to d 12 , but to the extent that no hydraulic braking force L5 is generated. Due to the pressure applied from the motor piston 28, the central portion 423 of the reaction plate 420 is larger than Figure 4A The protrusion in the middle is more, but it still does not abut against the operating rod 12.

[0088] Time t 13 and time t 14 The period between is the period during which the electric control unit 50 disables the regenerative braking mode and activates the hydraulic braking mode. During this period, the regenerative braking force L4 decreases, while the hydraulic braking force L5 increases by an amount equal to the amount by which the braking force decreases. 13 and time t 14 The period between is a period for increasing the hydraulic braking force L5. In the braking system according to the embodiment of the present disclosure, the electric booster unit 20 is driven to 13 and time t 14The hydraulic braking force is generated during the period of time, and the hydraulic braking force causes the motor piston 28 to move from d 12 Move to d 13 And compress the master cylinder 14. Figure 4C As shown, at time t 14 , the displacement of the operating rod 12 does not change from r 12 , only the displacement of motor piston 28 changes. Because operating rod 12 still does not abut reaction plate 420, total pedal force L1 is affected only by pedal force L2 of elastic body 17. Therefore, the driver does not experience an unnatural feeling during the period of increased hydraulic braking force. During this entire period, total pedal force L1 is equal to pedal force L2 of elastic body 17 because operating rod 12 does not abut center portion 423 of reaction plate 420.

[0089] Figure 5 This is a graph illustrating the relationship between the total pedal force, the pedal force of the elastic body, the pedal force of the reaction plate, the regenerative braking force, and the hydraulic braking force with respect to time if the amount of pedal force increases while regenerative braking is disabled during braking when the electric control unit alone performs regenerative braking. Figures 6A to 6C Is used to illustrate Figure 5 Starting point, time t 23 and time t 24 A diagram showing how the operation is performed.

[0090] Figure 6A Depicts Figure 5 The operation at the starting point, Figure 6B Depicts Figure 5 Time t 23 The operation at Figure 6C Depicts Figure 5 Time t 24 Here, the braking system is Figure 5 The starting point and time t in the graph are depicted 23 The operation within the period between the start and the time t 13 The operations in the period between are similar, so their description is omitted.

[0091] At time t 23 , the electric control unit 50 disables the regenerative braking mode and starts setting the hydraulic braking mode. 23 and time t 24 During the time period between , the regenerative braking force L4 decreases, while the hydraulic braking force L5 increases. Figure 5 As shown, the driver increases the amount of pedal effort during this period, so the required hydraulic braking force L5 is greater than the maximum amount L4 of the existing braking force.

[0092] Figure 5 The hydraulic braking force L5 shown at time t23 and time t 24 The increase in the period between Figure 3 The time t shown 13 and time t 14 The increase in the period between.

[0093] Even so, the brake system according to the embodiment of the present disclosure prevents the driver from having an unnatural pedaling feeling.

[0094] like Figure 6B and Figure 6C As shown, the displacement of the operating lever 12 increases from r to 22 Move to r 23 In addition, as the electric booster unit 20 is driven, the motor piston 28 compresses the disc unit 42, which causes the displacement of the disc unit 42 to change from d 22 Move to d 23 And compress the master cylinder 14, thereby generating hydraulic pressure. Figure 6C As shown, since the operating rod 12 and the central portion 423 of the reaction plate 420 do not abut against each other, the driver is only affected by the pedal force of the elastic body 17. Therefore, despite the change in the hydraulic pressure in the master cylinder 14, the driver will not have an unnatural pedaling feeling.

[0095] Figure 7 is a graph illustrating the relationship between the total pedal force, the pedal force of the elastic body, the pedal force of the reaction plate, the regenerative braking force, and the hydraulic braking force with respect to time when the electric control unit performs regenerative braking and hydraulic braking if regenerative braking is disabled during braking. Figures 8A to 8C Is used to illustrate Figure 7 Starting point, time t 34 and time t 35 A diagram showing how the operation is performed.

[0096] Figure 8A Depicted in Figure 7 The operation at the starting point, Figure 8B Depicts Figure 7 Time t 34 The operation at Figure 8C Depicts Figure 7 Time t 35 Operation at.

[0097] Figure 7 The starting point is the time point when the driver starts to step on the pedal 11, at which time the operating lever 12 is positioned at r 31 , and a total pedal force L1 is generated. Since the operating rod 12 is separated from the central portion 423 of the reaction plate 420, the pedal force L3 caused by the reaction force of the reaction plate 420 is not generated.

[0098] At the starting point and as the time t for the initial duration of the driver's depression of the pedal 11 31 During this period, the pedal force L2 generated by the compression of the elastic body 17 gradually increases.

[0099] Time t 31 and time t 32 The period in between is a period during which the corresponding braking force is generated as the amount of force applied to the pedal 11 by the driver increases. Figure 7 It is illustrated that the electric control unit 50 first activates the regenerative braking mode to brake the vehicle within this period, during which the hydraulic braking force L5 is not generated but the regenerative braking force L4 is gradually increased.

[0100] Time t 32 and time t 33 The period between is the period in which the hydraulic braking force L5 is generated due to the determination that the electric control unit 50 should activate the hydraulic braking mode, including more force applied by the driver on the pedal 11. During this period, the regenerative braking force L4 is maintained, but the electric booster unit 20 is driven to compress the motor piston 28 and increase the hydraulic pressure supplied to the multiple wheel brakes (not shown). During this process, the operating rod 12 also moves toward the master cylinder 14 and compresses the protruding central portion 423 of the reaction plate 420. Because the operating rod 12 abuts the central portion 423 of the reaction plate 420, the driver feels an additional pedal force L3. Here, the total pedal force L1 is the sum of the pedal force L2 of the elastic body 17 and the pedal force L3 of the reaction plate 420.

[0101] Time t 33 and time t 34 The period between is the period during which the amount of force applied by the driver to the pedal 11 is maintained. During this period, the amount of braking force required by the driver does not change, so the regenerative braking force L4 and the hydraulic braking force L5 are also maintained constant. Figure 8B As shown, the motor piston 28 is at time t 34 Compressing the reaction disk 420 causes the displacement of the disk unit 42 to be as Figure 8B Move to d 32 The central portion 423 of the reaction plate 420 is larger than the central portion 423 of the reaction plate 420 due to the pressure applied from the motor piston 28. Figure 8A The protrusion in the middle is more and abuts against the operating rod 12. During this period, the driver increases the amount of pedal effort to generate the hydraulic braking force L5, so the displacement of the operating rod 12 also moves to r 32 .

[0102] Time t 34 and time t 35The period between is a period during which the electric control unit 50 disables the regenerative braking mode and increases the hydraulic braking force by an amount equal to the reduction in the regenerative braking force. 34 and time t 35 The period in between is a period of increasing the hydraulic braking force L5. As the brake oil in the master cylinder 14 flows to the plurality of wheel brakes (not shown), the hydraulic pressure in the master cylinder 14 decreases.

[0103] In the braking system according to the embodiment of the present disclosure, the electric booster unit 20 is driven to 34 and time t 35 The hydraulic braking force is increased during the period of time, and the hydraulic braking force causes the motor piston 28 to move from d 32 Move to d 33 And further compress the master cylinder 14. Figure 8C As shown, at time t 35 , the displacement of the operating rod 12 does not change from r 12 The total pedal force L1 is affected by the pedal force L2 of the elastic body 17 and the pedal force L3 of the reaction plate 420. However, even under the influence of the pedal force L3 of the reaction plate 420, the total pedal force L1 does not change. This will be described in detail below.

[0104] when Figure 8B The pedal force felt by the driver is represented by F1 and Figure 8C When the pedal force felt by the driver is represented by F2, F1 and F2 satisfy equation 1:

[0105] [Equation 1]

[0106] F1=P rd1 A1+KX1

[0107] F2=P rd2 A2+KX2

[0108] Among them, P rd1 refers to Figure 8B The pressure applied from the reaction plate 420 to the operating rod 12, A1 refers to Figure 8B The contact area between the reaction plate 420 and the operating rod 12, K refers to the elastic coefficient of the elastic body 17, X1 refers to Figure 8B The distance that the elastic body 17 is compressed, P rd2 refers to Figure 8C The pressure applied from the reaction plate 420 to the operating rod 12, A2 refers to Figure 8C The contact area between the reaction plate 420 and the operating rod in FIG, and X2 refers to Figure 8CThe distance that the elastic body 17 is compressed.

[0109] exist Figure 8B and Figure 8C During the period between the two, the displacement of the operating rod 12 is maintained at point r 32 , so X1=X2. Therefore, KX1=KX2.

[0110] exist Figure 8C In the present embodiment, the hydraulic braking force needs to be increased by an amount equal to the reduction in the regenerative braking force, so the motor piston 28 moves further forward toward the master cylinder 14. The motor piston 28 further compresses the reaction plate 420 while maintaining the displacement of the operating rod 12. Therefore, the center portion 423 of the reaction plate 420 made of elastic material further protrudes, and the reaction plate 420 has a higher pressure (P rd1 <P rd2 ).

[0111] However, even if the pressure applied from the reaction plate 420 to the operating rod 12 changes, Figure 8C The central portion 423 of the reaction plate 420 further protrudes, thereby reducing the contact area with the operating rod 12. Therefore, A1>A2.

[0112] Although P rd1 <P rd2 , because A1>A2, so ≈P rd1 A1≈P rd2 A2. In the present disclosure, the reaction disc 420 is made of an elastic material, and the protrusion amount and the contact area with the operating rod 12 can be changed as the elasticity of the reaction disc 420 changes. The reaction disc 420 can be designed so that P rd1 A1=P rd2 A2, thereby eliminating any difference between the pedal forces F1 and F2 felt by the driver while the regenerative braking force is reduced and the hydraulic braking force is increased.

[0113] Figure 9 This is a graph used to illustrate the relationship between the total pedal force, the pedal force of the elastic body, the pedal force of the reaction plate, the regenerative braking force, and the hydraulic braking force with respect to time if the amount of pedal force increases while regenerative braking is disabled during braking when the electric control unit alone performs regenerative braking. 10A to 10C Is used to illustrate Figure 9 Starting point, time t 44 and time t 45 A diagram showing how the operation is performed.

[0114] Figure 10A Depicts Figure 9 The operation at the starting point, Figure 10B Depicts Figure 9Time t 44 The operation at Figure 10C Depicts Figure 9 Time t 45 Here, the braking system is Figure 9 The starting point and time t in the graph are depicted 44 The operation in the period between the start and time t 34 The operations in the period between are similar, so their description will be omitted.

[0115] At time t 44 , the electric control unit 50 disables the regenerative braking mode and drives the electric booster unit 20 to increase the hydraulic braking force L5. 44 and time t 45 During the period between , the regenerative braking force L4 decreases, while the hydraulic braking force L5 increases. Figure 9 As shown, the driver increases the amount of pedal effort during this period, so the required hydraulic braking force L5 is greater than the maximum amount L4 of the existing braking force.

[0116] Figure 9 The hydraulic braking force L5 shown at time t 44 and time t 45 The increase in the period between Figure 7 The time t shown 34 and time t 35 The increase in the period between.

[0117] Even so, the brake system according to the embodiment of the present disclosure prevents the driver from having an unnatural pedaling feeling.

[0118] like Figure 10B and Figure 10C As depicted, the displacement of the operating lever 12 increases from r to 42 Move to r 43 In addition, as the electric booster unit 20 is driven, the motor piston 28 compresses the disc unit 42, which causes the displacement of the disc unit 42 from r 42 Move to r 43 And compress the master cylinder 14, thereby increasing the hydraulic pressure. Figure 10B and Figure 10C During operation, the operating rod 12 continues to abut against the center portion 423 of the reaction plate 420, but the pedal force felt by the driver hardly changes as explained with reference to Equation 1. Therefore, the driver does not feel an unnatural pedaling feeling despite the change in the hydraulic pressure in the master cylinder 14.

[0119] Figure 11 is a flowchart of a method of controlling a braking system according to an embodiment of the present disclosure. Figure 11The flowchart depicted in FIG. 1 is a description of some of the various braking methods, and the electric control unit 50 does not necessarily include Figure 11 algorithm, but may include multiple braking algorithms that include this algorithm. Figure 11 This is a flowchart drawn assuming that only the regenerative brake unit is driven. In addition, the electric control unit 50 may include a method for performing braking by driving the hydraulic brake unit alone.

[0120] The electric control unit 50 receives a brake pedal signal (S10). That is, the electric control unit 50 receives a signal from the brake pedal 11 to check whether the driver has stepped on the pedal 11. If the electric control unit 50 does not receive a brake pedal signal, it determines that there is no braking situation and does not perform braking. Figure 11 control process.

[0121] If the electric control unit 50 receives the brake pedal signal, it calculates the required total braking force (S20). The required total braking force is set based on the amount of force applied by the driver to the pedal 11. If an autonomous driving function is provided, the electric control unit 50 may also determine the required total braking force. When the driver depresses the pedal 11, the electric control unit 50 calculates the total braking force required to brake the vehicle based on the amount of force applied to the pedal 11, as measured by a pedal travel sensor (not shown).

[0122] The electric control unit 50 calculates the required regenerative braking force based on the required total braking force (S30). After calculating the required regenerative braking force, the electric control unit 50 drives the regenerative brake unit (not shown) based on the calculated required regenerative braking force (S40).

[0123] When the regenerative braking unit (not shown) is being driven, the electric control unit 50 determines whether to stop regenerative braking (S50). The electric control unit 50 can determine whether to stop regenerative braking by itself or by using a regenerative braking interruption signal received from the outside.

[0124] If it is determined that regenerative braking is to be stopped, the electric control unit 50 calculates the required hydraulic braking force corresponding to the stop of regenerative braking (S60). Once the electric control unit 50 disables the regenerative braking mode, the regenerative braking force is reduced. The electric control unit 50 senses the amount of reduction in the regenerative braking force and calculates the hydraulic braking force required to compensate for the sensed reduction in braking force.

[0125] The electric control unit 50 calculates the required displacement of the motor piston 28 corresponding to the required hydraulic braking force (S70). The required displacement of the motor piston 28 is determined based on the displacement of the motor piston 28 at the time when the electric control unit 50 stops regenerative braking.

[0126] The electric control unit 50 drives the electric booster unit 20 so that the motor piston 28 moves to the desired displacement (S80). The electric control unit 50 moves the motor piston 28 toward the master cylinder 14, driving the electric booster unit 20 to compress the reaction plate 420. Here, the reaction plate 420 can be made of an elastic material, and the motor piston 28 can abut against the outer periphery of the reaction plate 420. As the motor piston 28 compresses the reaction plate 420, the central portion 423 of the reaction plate 420 can protrude toward the operating rod 12. If the protruding reaction plate 420 abuts the operating rod 12, it provides a reaction force to the operating rod 12. This reaction force is part of the pedal force felt by the driver. In the present disclosure, as explained with reference to the above equation 1, even if the reaction plate 420 and the operating rod 12 abut against each other, the driver will not feel an unnatural pedaling sensation during the period when the regenerative braking force decreases and the hydraulic braking force increases.

[0127] After step S80 , the algorithm of the present disclosure is completed.

[0128] Hereinafter, a brake system and a method of controlling the brake system according to a second embodiment of the present disclosure are described.

[0129] It should be noted that in order to facilitate understanding of the operation process of the braking system 1b, Figures 12 to 14C and 16A to 16C The conceptual diagram of the brake system 1 b shown is briefly shown and may be different from the actual detailed shape of the brake system 1 b .

[0130] Braking system structure

[0131] Figure 12 is a conceptual diagram illustrating an initial state of a brake system according to a second embodiment of the present disclosure.

[0132] Reference Figure 12 , a brake system 1b according to the second embodiment of the present disclosure includes all or some of a pedal main unit 10b, an electric booster unit 20b, a housing 30b, a pedal force generating unit 40b, and an electric control unit 50b.

[0133] When the driver steps on the pedal 11b, the pedal main unit 10b transmits the stepping to the master cylinder 14b. The pedal main unit 10b includes all or some of an operating rod 12b, a push rod 13b, a master cylinder 14b, and a return spring 15b.

[0134] Pedal 11b is a part that the driver steps on to slow down or stop the vehicle. When the driver steps on pedal 11b and the first end of operating lever 12b is pressed with a predetermined pressure or greater, the second end of operating lever 12b presses reaction plate 32b. In this case, the stroke of pedal 11b is sensed by a separately provided pedal stroke sensor (not shown).

[0135] The operating rod 12b is a medium that transmits the driver's pedal force to the reaction plate 420b. The first end of the operating rod 12b is connected to the pedal 11b. The pedal force F transmitted to the reaction plate 420b RD The force is transmitted to the master cylinder 14b via the operating rod 12b. In the initial state when the pedal 11b is stepped on, the second end of the operating rod 12b is spaced apart from the reaction plate 420b. As the pedal 11b is stepped on, the second end of the operating rod 12b moves forward toward the reaction plate 420b.

[0136] The push rod 13b is at least partially inserted into the master cylinder 14b. The push rod 13b reciprocates in the longitudinal direction of the master cylinder 14b within the master cylinder 14b and can push the brake fluid stored in the master cylinder 14b when moving forward.

[0137] The master cylinder 14b is configured to hold brake fluid therein. When the brake fluid in the master cylinder 14b is compressed, hydraulic pressure for braking is generated. The generated hydraulic pressure is transmitted to a plurality of wheel brake assemblies (not shown).

[0138] The return spring 15b is disposed in the master cylinder 14b and is compressed or expanded by the reciprocating motion of the push rod 13b. Preferably, the return spring 15b may be a coil spring. However, the present disclosure is not necessarily limited thereto, and the return spring may be a leaf spring or an elastomer such as rubber. In addition, although not shown in the present disclosure, the return spring 15b may be disposed in the housing of the electric booster unit 20b. The return spring 15b may be disposed in the master cylinder 14b or the electric booster unit 20b so as to be pressed by a portion of the force transmitted by the operating rod 12b and the electric booster unit 20b.

[0139] The electric booster unit 20b is configured to increase the pedal effort of the driver. The electric booster unit 20b includes all or some of a motor 22b, a gear device 24b, a screw shaft 26b, and a motor piston 28b.

[0140] The motor 22b is configured to rotate forward or reverse in response to a signal from the electric control unit 50b.

[0141] The gear arrangement 24b is configured to transmit the torque of the motor 22b to the screw shaft 26b. The gear arrangement 24b includes all or some of the first gear 240b, the second gear 242b, and the third gear 244b.

[0142] First gear 240b primarily receives torque transmitted from motor 22b and transfers the torque to second gear 242b. Second gear 242b transfers the torque received from first gear 240b to third gear 244b. Third gear 244b transfers the torque received from second gear 242b to screw shaft 26b. Depending on the gear ratio between first gear 240b and third gear 244b, the rotational speed can be reduced or increased at a predetermined ratio while torque is transferred from first gear 240b to third gear 244b.

[0143] The screw shaft 26b is configured to convert the torque transmitted by the gear device 24b into a linear motion. The screw shaft 26b includes all or some of the first shaft 260b and the second shaft 262b.

[0144] First shaft 260b rotates while being restrained by third gear 244b. Second shaft 262b is configured to convert the rotational motion of first shaft 260b into linear motion. Preferably, first shaft 260b may comprise a pinion, second shaft 262b, and a rack. A first end of second shaft 262b is connected to motor piston 28b. Therefore, when motor 22b is driven, second shaft 262b moves reaction plate 420b forward or backward in the opposite direction.

[0145] The motor piston 28b reciprocates in the longitudinal direction of the master cylinder 14b by the force transmitted by the combination of the gear device 24b and the screw shaft 26b. The motor piston 28b is arranged so that its first end is pressed by the second shaft 262b and its second end presses the reaction plate 420b.

[0146] When the pedal 11b is not depressed (ie, there is no brake request signal), the motor piston 28b is positioned close to the first shaft 260b. Hereinafter, the position of the motor piston 28b in the above state is referred to as a "set position."

[0147] The housing 30b is configured to surround at least a portion of the pedal main unit 10b, at least a portion of the electric booster unit 20b, and at least a portion of the pedal force generating unit 40b. The housing 30b includes a spring seat 32b.

[0148] The spring seat 32b is fixed to the housing 30b, and at least a portion of the pedal spring unit 44b is attached to a surface of the spring seat 32b. When the driver steps on the pedal and the pedal spring unit 44b is pressed, the spring seat 32b supports the pedal spring unit 44b.

[0149] When the driver presses the pedal 11b, the pedal force generating unit 40b provides the driver with a pedal force. The pedal force generating unit 40b includes all or some of the disc unit 42b and the pedal spring unit 44b.

[0150] The disc unit 42b is configured to be pressed by one or more of the operating rod 12b and the motor piston 28b. The reaction force generated by the disc unit 42b to the pedal force is transmitted to the push rod 13b. The push rod 13b presses the brake oil stored in the master cylinder 14b, and at least a portion of the pressed brake oil is transmitted to the plurality of wheel brake assemblies, thereby generating a hydraulic braking force F. hyd .

[0151] The disk unit 42b includes a reaction disk 420b and a reaction disk receptacle 422b.

[0152] The reaction plate 420b is provided to be pressed by the operating rod 12b. When the first end of the operating rod 12b is pressed by the force applied by the driver to step on the pedal 11b, the second end of the operating rod 12b presses the reaction plate 420b.

[0153] Furthermore, the reaction disc 420b is configured to be pressed by the motor piston 28b. Figure 12 However, unless the electric control unit 50b generates a brake request signal, the motor piston 28b may be spaced apart from the reaction plate 420b.

[0154] Meanwhile, when the pedal 11b is pressed, one end of the operating rod 12b moves forward toward the reaction plate 420b, whereby they come into contact with each other, as shown in FIG. Figure 14B As shown. Figure 14B When the stepped pedal 11b shown is further pressed, the outer circumference of the reaction disc 420b is pressed by the motor piston 28b, and the central portion of the reaction disc 420b is pressed by the operating rod 12b. To this end, the end face of the motor piston 28b can be formed into a roughly annular shape, and the operating rod 12b can pass through the open central portion of the motor piston 28b. In this case, the operating rod 12b and the reaction disc 420b are coaxially arranged. At the same time, the present disclosure is not limited to this, and the outer circumference of the reaction disc 420b can be pressed by the operating rod 12b, and the central portion of the reaction disc 420b can be pressed by the motor piston 28b. Even in this case, it is preferred that the operating rod 12b and the reaction disc 420b are coaxially arranged.

[0155] The reaction plate 420b is made of a compressible material. For example, at least a portion of the reaction plate 420b may be made of rubber. When the reaction plate 420b is pressed by one or more of the operating rod 12b and the motor piston 28b, the reaction force generated by the pressing force is transmitted to the driver through the operating rod 12b and constitutes a part of the pedal force felt by the driver. Hereinafter, the pedal force generated when the reaction plate 420b is compressed by an external force is referred to as F. RD express.

[0156] Reaction disc receptacle 422b is configured to accommodate at least a portion of reaction disc 420b in an accommodation space formed therein. When a first side of reaction disc receptacle 422b is pressed by one or more of operating rod 12b and motor piston 28b, a second side of reaction disc receptacle 422b presses push rod 13.

[0157] The pedal spring unit 44b is connected to the operating rod 12b on the first side and to the spring seat 32b on the second side. When the relative distance between the pedal 11b and the spring seat 32b increases or decreases, the pedal spring unit 44b generates a tensile force or a compressive force. The reaction force generated when the pedal spring unit 44b is compressed is transmitted to the driver through the operating rod 12b and constitutes a part of the pedal force felt by the driver. In the following, the pedal force generated when the pedal spring unit 44b is compressed by an external force is referred to as F spring express.

[0158] The pedal spring unit 44b includes a spring 440b and a damper 442b. Although the spring 440b and the damper 442b are connected in series in the present disclosure, the present disclosure is not limited thereto, and the spring 440b and the damper 442b may be connected in parallel.

[0159] The total pedal force F transmitted to the driver pedal It can be determined as the pedal force F generated by the reaction force to the compressive force of the disc unit 42b. RD and the pedal force F generated by the reaction force to the compression force of the pedal spring unit 44b. spring sum.

[0160] The electric control unit 50b generates a brake request signal based on a pedal stroke S received from a pedal stroke sensor (not shown). The brake request signal is an electrical signal that causes at least some of the plurality of wheel brake assemblies (not shown) to generate a braking force.

[0161] The electric control unit 50b calculates the total braking force F requested for braking the vehicle based on the pedal stroke S. total In addition, the electric control unit 50b determines whether regenerative braking is performed, and controls the electric booster unit 20b differently depending on whether regenerative braking is performed. Figures 14A to 15 The operation of the braking system 1b when the regenerative braking mode starts will be described with reference to Figures 16A to 17 The operation of the brake system 1b at the start of the hydraulic braking mode will be described.

[0162] Dead stroke state

[0163] Figure 13 : is a conceptual diagram showing a dead stroke state of a brake system according to a second embodiment of the present disclosure. Figure 13 The state in which the driver starts to press the pedal 11 b is shown, that is, the state in which the electric control unit 50 b starts to generate a brake request signal. Figure 13 A state where the pedal stroke S satisfies s<s1 is shown.

[0164] When the status changes from Figure 12 Change to Figure 13 (ie, when s<s1 and s increases), even if the operating rod 12b moves forward, one end of the operating rod 12b does not contact the reaction plate 420b. Therefore, the pedal force F generated by the reaction plate 420b RD is not transmitted to the driver. In this case, the distance between the spring seat 32b and the operating rod 12b is reduced and at least a portion of the pedal spring unit 44b is compressed. The F generated by the reaction force against the compression force of the pedal spring unit 44b spring is passed to the driver and is F pedal That is, the relationship F spring =F pedal .

[0165] Even if the pedal 11b is Figures 12 to 13 In other words, the brake system 1b is in the state of Figures 12 to 13 The state shown in is in the dead stroke period.

[0166] Regenerative braking mode

[0167] The regenerative braking mode of the brake system according to the second embodiment of the present disclosure includes a first regenerative braking mode and a second regenerative braking mode.

[0168] When braking in the first regenerative braking mode, the braking system 1b performs braking using only the regenerative brake provided in the vehicle. That is, even if only the regenerative braking force F generated by the regenerative braking unit (not shown) is reg Satisfy the requested total braking force F total When braking in the second regenerative braking mode, the braking system 1b performs braking using both regenerative braking and hydraulic braking. That is, the requested total braking force F total is the regenerative braking force F reg and hydraulic braking force F hyd In this disclosure, reference is made to Figure 14A The operation of the braking system in the first regenerative braking mode is described with reference to Figures 14B to 14C The operation of the braking system 1 b in the second regenerative braking mode will be described.

[0169] Figure 14AIt is a conceptual diagram showing the first regenerative braking mode state of a braking system according to a second embodiment of the present disclosure.

[0170] Specifically, Figure 14A The state s1 ≤ s < s2 is shown. When s = s1 is sensed by the pedal travel sensor, the electric control unit 50b controls a regenerative braking unit (not shown) to perform regenerative braking. When s1 ≤ s < s2 and s increases, the motor piston 28b moves forward and the reaction disk 420b is further compressed from the previous state. However, since the first end of the operating lever 12b and the reaction disk 420b do not contact each other, the pedal force F generated by the reaction disk 420b RD will not be transmitted to the driver. Therefore, the total pedal force F pedal is determined to be only the pedal force F generated by the pedal spring unit 44b spring . That is, in the first regenerative braking mode, the braking system 1b satisfies F pedal = F spring .

[0171] In addition, since the disk unit 42b is within a displacement where no hydraulic pressure is generated in the first regenerative braking mode, the disk unit 42b does not transmit force to the brake oil stored in the master cylinder 14b. Therefore, the total requested braking force F total is determined to be only the regenerative braking force F reg . That is, in the first regenerative braking mode, the braking system 1b satisfies F total = F reg .

[0172] Figure 14B And Figure 14C are conceptual diagrams showing the state after the start of the second regenerative braking mode of the braking system according to the second embodiment of the present disclosure. Specifically, Figure 14B The state s = s2 is shown in, and Figure 14C The state s > s2 is shown in. When s = s2, the first end of the operating lever 12b and the reaction disk 420b contact each other. Therefore, F, which is the reaction force to the compression force generated when pressing the reaction disk 420b, can be transmitted to the driver. At the same time, the displacement generated by the motor piston 28b calculated by the electric control unit 50b to generate an appropriate pedal force to generate F RD is called the first displacement d1.

[0173] In addition, at least a part of the reaction disk container 422b is inserted into the master cylinder 14b from the time point s = s2. That is, when the disk unit 42b presses the brake oil in the master cylinder 14b, a hydraulic braking force F hyd can be generated.

[0174] At​​ Figures 14B to 14C In the state s≥s2 shown, the total pedal force F pedal The pedal force F generated by the disc unit 42b is determined to be RD and the pedal force F generated by the pedal spring unit 44b spring That is, in the second regenerative braking mode, the braking system 1b satisfies F pedal =F spring +F RD .

[0175] Furthermore, in the state s≥s2, the requested total braking force is determined as the hydraulic braking force F generated when the disc unit 42b presses the inside of the master cylinder 14b. hyd and regenerative braking force F reg That is, in the second regenerative braking mode, the braking system 1b satisfies F total =F reg +F hyd .

[0176] In the second regenerative braking mode, the displacement d of the motor piston 28b is such that F RD The first shift d1 and produces F hyd The sum of the second shift d2.

[0177] Figure 15 : is a graph showing the relationship between the pedal stroke and the pedal force in each period in the regenerative braking mode of the braking system according to the second embodiment of the present disclosure. Figure 15 The pedal force and pressure of the brake system 1b are described based on the increase of the pedal stroke S. Figures 12 to 14C Changes in the status shown.

[0178] The operating state s<s1 of the brake system 1b is Figure 13 As the pedal 11b is stepped on, the operating rod 12b moves forward toward the reaction plate 420b. In this case, as Figure 13 As shown, the first end of the operating rod 12b is positioned so as not to affect the total pedal force F pedal For example, the first end of the operating rod 12b may be spaced apart from the reaction plate 420b. Thus, the total pedal force F provided by the driver is constituted. pedal The force is only the pedal force F generated by the pedal spring unit 44b spring Therefore, when s<s1, the braking system 1b according to the present disclosure satisfies F pedal =F spring The pedal force F generated by the pedal spring unit 44b spring It may increase substantially linearly in proportion to the compressive force of the pedal spring unit 44b.

[0179] Meanwhile, in this state, no regenerative braking force F is generated regardless of the pedal force of the pedal 11b. reg and hydraulic braking force F hyd Dead stroke period.

[0180] The operating state of the brake system 1b is s1≤s<s2 and Figure 14A As the pedal 11b is stepped on, the motor piston 28b moves from Figure 13 The state shown is further moved forward and presses the reaction plate 420b. However, since the first end of the operating rod 12b is spaced apart from the reaction plate 420b, the F pedal The force is only F spring Therefore, when s1≤s≤s2, in the regenerative braking mode, the braking system 1b according to the present disclosure satisfies F pedal =F spring The pedal force F generated by the pedal spring unit 44b spring It may increase substantially linearly in proportion to the compressive force of the pedal spring unit 44b.

[0181] At the same time, in this state, the regenerative braking force F reg Therefore, when s1≤s<s2, in the regenerative braking mode, the braking system 1b according to the present disclosure satisfies F total =F reg .

[0182] The operating state s=s2 of the brake system 1b is Figure 14B The operating state shown corresponds to the state shown. The motor piston 28b moves forward, and the center portion of the reaction plate 420b, whose outer periphery is further pressed, further protrudes. In addition, the operating rod 12b also moves forward. Therefore, the first end of the operating rod 12b contacts the reaction plate 420b at the time point s=s2. Therefore, the pedal force F generated by the reaction plate 420b RD Therefore, when s=s2, in the regenerative braking mode, the braking system 1b according to the present disclosure satisfies F pedal =F spring +F RD .

[0183] On the other hand, in this state, the disc unit 42b starts to press the brake oil stored in the master cylinder 14b, thereby generating a hydraulic braking force F hyd Therefore, when s=s2, in the regenerative braking mode, the braking system 1b according to the present disclosure satisfies F total =F reg +F hyd .

[0184] The operating state s>s2 of the brake system 1b is Figure 14C corresponds to the operating state shown. When s > s2, in the regenerative braking mode, the braking system 1b according to the present disclosure satisfies F pedal = F spring + F RD . At the same time, in the present disclosure, the pedal force generated by the reaction force of the compression force of the return spring 15b provided in the master cylinder 14b is not considered.

[0185] The force of the operating lever 12b pressing the reaction disk 420b and the force of the motor piston 28b pressing the reaction disk 420b are transmitted to the brake fluid stored in the master cylinder 14b. At least a part of the force transmitted to the master cylinder 14b generates a hydraulic braking force F hyd . Therefore, when s > s2, in the regenerative braking mode, the braking system 1b according to the present disclosure satisfies F total = F reg + F hyd .

[0186] Hydraulic braking mode

[0187] When braking in the hydraulic braking mode, the braking system 1b according to the second embodiment of the present disclosure does not use the regenerative braking unit provided in the vehicle to perform braking. Therefore, the total requested braking force F total is only satisfied by the hydraulic braking force F hyd . Therefore, the braking system 1b satisfies F total = F hyd throughout the entire period of the hydraulic braking mode.

[0188] The hydraulic braking mode of the braking system according to the second embodiment of the present disclosure includes a first hydraulic braking mode and a second hydraulic braking mode. In the first hydraulic braking mode, the total pedal force F pedal is only satisfied by the pedal force F spring generated by the pedal spring unit 44b. In the second hydraulic braking mode, the total pedal force F pedal is only satisfied by the sum of F spring and the pedal force F RD of the disk unit 42b. In the present disclosure, the operation of the braking system in the first hydraulic braking mode is described with reference to Figure 16A , and the operation of the braking system 1b in the second hydraulic braking mode is described with reference to Figures 16B to 16C .

[0189] At the same time, the operating state s < s3 of the braking system 1b can be the same as or equivalent to the operating state s < s1 of the braking system 1b in the regenerative braking mode. Therefore, the descriptions in Figure 12 and Figure 13 are referred to for this case.

[0190] Figure 16A : is a conceptual diagram showing a first hydraulic braking mode state of a braking system according to a second embodiment of the present disclosure. Figure 16A The state s3≤s<s4 is shown in FIG. When s=s3 is detected by the pedal stroke sensor, the electric control unit 50b controls the brake system 1b to perform hydraulic braking using the pedal main unit 10b. When s3≤s<s4 and S increases, the motor piston 28b moves forward and the reaction plate 420b is further compressed from the previous state. However, since the first end of the operating rod 12b and the reaction plate 420b are not in contact with each other, the pedal force F generated by the reaction plate 420b is RD is not transmitted to the driver. Therefore, the total pedal force F pedal The pedal force F is determined to be generated only by the pedal spring unit 44b. spring That is, in the first hydraulic braking mode, the braking system 1b satisfies F pedal =F spring At the same time, the pedal force F generated by the pedal spring unit 44b spring It may increase substantially linearly in proportion to the compressive force of the pedal spring unit 44b.

[0191] Figure 16B and Figure 16C : is a conceptual diagram showing a state after the second hydraulic braking mode of the brake system according to the second embodiment of the present disclosure starts. Figure 16B The state s=s4 is shown in FIG, and Figure 16C The state s>s4 is shown in FIG. When s=s4, the first end of the operating rod 12b and the reaction plate 420b are in contact with each other. Therefore, the F acting as a reaction force to the compression force generated when the reaction plate 420b is pressed can be RD That is, in the second hydraulic braking mode, the braking system 1b according to the present disclosure satisfies F pedal =F spring +F RD At the same time, the pedal force F generated by the pedal spring unit 44b spring It may increase substantially linearly in proportion to the compressive force of the pedal spring unit 44b.

[0192] Figure 17 : is a graph showing the relationship between the pedal stroke and the pedal force in each period in the hydraulic braking mode of the brake system according to the second embodiment of the present disclosure. Figure 17 Based on pedal stroke s b The increase in the pedal force and pressure of the brake system 1b describes the 16A to 16C Changes in the status shown.

[0193] The operating state s<s3 of the brake system 1b is Figures 12 to 13 For this period, reference is made to the description of s<s1 in the regenerative braking mode.

[0194] The operating state s3≤s<s4 of the brake system 1b is Figure 16A As the pedal 11b is stepped on, the motor piston 28b moves from Figure 13 The state shown is further moved forward and presses the reaction plate 420b. However, since the first end of the operating rod 12b is spaced apart from the reaction plate 420b, the F pedal The force is only F spring Therefore, when s3≤s<s4, in the hydraulic braking mode, the braking system 1b according to the present disclosure satisfies F pedal =F spring The pedal force F generated by the pedal spring unit 44b spring It may increase substantially linearly in proportion to the compressive force of the pedal spring unit 44b.

[0195] The operating state s=s4 of the brake system 1b is Figure 16B The operating state shown corresponds to the following. The motor piston 28b moves forward, and the center portion of the reaction plate 420b, whose outer periphery is further pressed, further protrudes. In addition, the operating rod 12b also moves forward. Therefore, the first end of the operating rod 12b contacts the reaction plate 420b at time s=s4. Therefore, the pedal force F generated by the reaction plate 420b RD Therefore, when s=s2, in the hydraulic braking mode, the braking system 1b according to the present disclosure satisfies F pedal =F spring +F RD The pedal force F generated by the pedal spring unit 44b spring It may increase substantially linearly in proportion to the compressive force of the pedal spring unit 44b.

[0196] The operating state s>s4 of the brake system 1b is Figure 16C When s>s4, in the regenerative braking mode, the braking system 1b according to the present disclosure satisfies F pedal =F spring +F RD Meanwhile, a pedal force generated by a reaction force to a compression force of a return spring 15b provided in the master cylinder 14b is not considered in the present disclosure.

[0197] Method of controlling a braking system

[0198] Although in this disclosure Figures 18 and 19 The processes are executed sequentially in chronological order, but part or all of the processes may be executed simultaneously regardless of the order.

[0199] Figure 18 is a flowchart illustrating a method of controlling a brake system according to a second embodiment of the present disclosure.

[0200] Reference Figure 18 When the driver steps on the pedal 11b, a brake pedal signal is input to the electric control unit 50b (S700b).

[0201] When the brake pedal signal is input, the electric control unit 50b calculates the requested total braking force F based on the stroke value sensed by the pedal stroke sensor PTS. total (S710b).

[0202] Thereafter, the electric control unit 50b determines whether to use the regenerative braking mode to brake the vehicle (S720b). The braking force generated by the regenerative braking unit in this case is defined as the regenerative braking force F reg .

[0203] When the electric control unit 50b determines to drive the regenerative braking unit, the electric control unit 50b brakes the vehicle by starting the regenerative braking mode (S740b). Meanwhile, when it is determined not to drive the regenerative braking unit, the electric control unit 50b brakes the vehicle by starting the hydraulic braking mode (S750b).

[0204] When the regenerative braking mode or the hydraulic braking mode is activated, the electric control unit 50b calculates the total braking force F that can be generated. total and the total pedal force F pedal The displacement of the motor piston d b (S760b).

[0205] The electric control unit 50b drives the electric booster unit 20b based on the calculated displacement d, thereby controlling the brake system 1b so that the motor piston can move by a desired displacement d (S770b).

[0206] Figure 19 1 is a flowchart showing a control method in a second regenerative braking mode state of a brake system according to a second embodiment of the present disclosure. Figure 19 The detailed control method of the electric booster unit 20b in the second regenerative braking mode is described. Figure 19 The contents of the S810b are related to Figure 18 The processing of S710b is the same as that of S710b, so it will not be described in detail.

[0207] In the second regenerative braking mode, the electric control unit 50b calculates the requested regenerative braking force F reg (S820b).

[0208] In this case, the electric control unit 50b calculates the first displacement d1 of the motor piston 28b, thereby applying an appropriate pedal force F to the motor based on the sensed pedal stroke s. pedal Meanwhile, although the reference point d1 is described and illustrated in the present disclosure as the motor piston 28b being in the set position (see Figure 14B ), but the reference point is not necessarily limited thereto. For example, d1 may be a distance from the first axis 260b as a fixed member.

[0209] The electric control unit 50b calculates the appropriate hydraulic braking force F based on the sensed pedal stroke s. hyd In this case, F hyd =F total -F reg Used for calculation (S840b).

[0210] The electric control unit 50b calculates the second displacement d2 of the motor piston 28b based on the sensed pedal stroke s b Generate appropriate hydraulic braking force F hyd (S850b).

[0211] The electric control unit 50b calculates the appropriate displacement d of the motor piston using d1 and d2. In this case, d=d1+d2 is satisfied. Thereafter, the control unit drives the electric booster unit 20b using the calculated d so that the displacement of the motor piston is the calculated d (S870b).

[0212] Hereinafter, a brake system and a method of controlling the brake system according to a third embodiment of the present disclosure are described.

[0213] Figure 20 is a cross-sectional view of a brake system according to a third embodiment of the present disclosure.

[0214] Reference Figure 20 , a brake system 1 c according to the third embodiment of the present disclosure includes all or some of a pedal main unit 10 c , an electric booster unit 20 c , a housing 30 c , a disc unit 42 c , and an electric control unit 50 c .

[0215] The pedal main unit 10 c includes all or some of the pedal 11 c , the rod assembly 60 c , the push rod 13 c , the master cylinder 14 c , and the return spring 15 c .

[0216] Pedal 11c is a part that the driver steps on to slow down or stop the vehicle. When the driver steps on pedal 11c and the first end of operating lever 12c is pressed with a predetermined pressure or greater, operating lever 12c moves toward reaction plate 420c. In this case, the stroke of pedal 11c can be sensed by a separately provided pedal stroke sensor (not shown). The first end of operating lever 12c can be arranged to contact the center portion of reaction plate 420c.

[0217] The rod assembly 60c includes an operating rod 12c, an elastic body 17c, and an elastic body connector 16c.

[0218] The operating rod 12c transmits the driver's pedal force to the reaction plate 420c. The first end of the operating rod 12c is connected to the pedal 11c. The operating rod 12c, in conjunction with the motor piston 28c, pushes the reaction plate 420c toward the master cylinder 14c, thereby depressing the master cylinder 14c. Initially, when the pedal 11c is depressed, the second end of the operating rod 12c is spaced apart from the reaction plate 420c. As the pedal 11c is depressed, the second end of the operating rod 12c moves forward toward the reaction plate 420c.

[0219] The first end of the elastic body 17c is in contact with the operating rod 12c and the second end thereof is arranged to be in contact with the elastic body connector 16c. The elastic body connector 16c may be formed on the first surface of the screw shaft, such as Figure 20 As shown, but may be formed on a portion of the second surface whereby the motor piston 28c contacts the reaction plate 420c, as shown Figures 23A to 23C Furthermore, the elastomeric connector 16c may be formed in a space where it can move along with the linear motion of the motor piston 28c.

[0220] Elastomer 17c generates an elastic force in response to the movement of operating rod 12c. Specifically, when the driver steps on pedal 11c, operating rod 12c compresses elastomer 17c while moving toward reaction plate 420c. The compressed elastomer 17c generates a reaction force, which is a spring force, thereby providing pedal force to the driver. Since the second end of elastomer 17c is configured to contact elastomer connector 16c, elastomer 17c is only affected by the displacement of operating rod 12c and motor piston 28c. Even if operating rod 12c does not contact reaction plate 420c and reaction plate 420c does not generate a reaction force, the driver can still feel the pedal force through the reaction force of elastomer 17c.

[0221] The elastic body 17c may be a spring or may be a combination of a spring 171c and a damper 172c. Although the spring 171c and the damper 172c are connected in series in the present disclosure, the present disclosure is not limited thereto and the spring 171c and the damper 172c may be connected in parallel.

[0222] The push rod 13c is at least partially inserted into the master cylinder 14c. The push rod 13c reciprocates in the longitudinal direction of the master cylinder 14c within the master cylinder 14c and can press the brake fluid stored in the master cylinder 14c when moving forward.

[0223] The master cylinder 14c is configured to hold brake fluid therein. When the brake fluid in the master cylinder 14c is compressed, hydraulic pressure for braking is generated. The generated hydraulic pressure is transmitted to a plurality of wheel brakes (not shown).

[0224] The return spring 15c is provided in the master cylinder 14c and is compressed or expanded by the reciprocating motion of the push rod 13c. Preferably, the return spring 15c may be a coil spring. However, the present disclosure is not necessarily limited thereto, and the return spring may be a leaf spring or an elastomer such as rubber. In addition, although not shown in the present disclosure, the return spring 15c may be provided in the housing of the electric booster unit 20c. The return spring 15c may be provided in the master cylinder 14c or the electric booster unit 20c to be pressed by a portion of the force transmitted by any one or more of the operating rod 12c and the electric booster unit 20c.

[0225] The electric booster unit 20c is configured to increase the pedal effort of the driver. The electric booster unit 20c includes all or some of a motor 22c, a gear device 24c, a screw shaft 26c, and a motor piston 28c.

[0226] The motor 22c is configured to rotate forwardly or reversely about the axis of the motor 22c in response to a signal from the electric control unit 50c.

[0227] The gear arrangement 24c is configured to transmit the torque of the motor 22c to the screw shaft 26c. The gear arrangement 24c includes all or some of the first gear 240c, the second gear 242c, and the third gear 244c.

[0228] First gear 240c primarily receives torque transmitted from motor 22c and transfers the torque to second gear 242c. Second gear 242c transfers the torque received from first gear 240c to third gear 244c. Third gear 244c transfers the torque received from second gear 242c to screw shaft 26c. Depending on the gear ratio between first gear 240c and third gear 244c, the rotational speed can be reduced or increased at a predetermined ratio while torque is being transferred from first gear 240c to third gear 244c.

[0229] The screw shaft 26c is configured to convert the torque transmitted by the gear device 24c into a linear motion. The screw shaft 26c includes all or some of the first shaft 260c and the second shaft 262c.

[0230] First shaft 260c rotates while being restrained by third gear 244c. Second shaft 262c is configured to convert the rotational motion of first shaft 260c into linear motion. Preferably, first shaft 260c may comprise a pinion, second shaft 262c, and a rack. A first end of second shaft 262c is connected to motor piston 28c. Therefore, when motor 22c is driven, second shaft 262c causes reaction plate 420c to move forward or backward in the opposite direction.

[0231] The motor piston 28c reciprocates in the longitudinal direction of the master cylinder 14c by the force transmitted by the combination of the gear device 24c and the screw shaft 26c. The motor piston 28c is arranged so that its first end is pressed by the second shaft 262c and its second end presses the reaction plate 420c.

[0232] When the pedal 11 c is not depressed (ie, there is no brake request signal), the motor piston 28 c is positioned close to the first shaft 260 c.

[0233] The housing 30c is configured to surround at least a portion of the pedal main unit 10c, at least a portion of the electric booster unit 20c, and at least a portion of the disc unit 42c.

[0234] When the electric control unit 50c performs hydraulic braking, the disc unit 42c presses the master cylinder 14c, thereby providing hydraulic pressure to a plurality of wheel brakes (not shown). The disc unit 42c includes a reaction disc 420c and a reaction disc reservoir 422c.

[0235] The reaction plate 420c is configured to be pressed by any one or more of the operating rod 12c and the motor piston 28c. Figure 20 In the embodiment of the present invention, the reaction plate 420c and the motor piston 28c are in contact with each other. However, unless the electric control unit 50c generates a brake request signal, the motor piston 28c may be spaced apart from the reaction plate 420c.

[0236] The reaction disc 420c can be arranged in such a manner that the outer circumference of the reaction disc 420c (i.e., its outer edge) is pressed by the motor piston 28c, and the central portion of the reaction disc 420 is pressed by the operating rod 12c. To this end, the end face of the motor piston 28c can be formed into a roughly annular shape, and the operating rod 12c can pass through a hollow portion formed at the center of the motor piston 28c. In this case, the operating rod 12c and the reaction disc 420c are coaxially arranged. At the same time, the present disclosure is not limited to this, and other braking systems are also included in the present disclosure as long as the braking system has a device that can press the reaction disc 420c when the pedal 11c is stepped on and the motor 22c is driven.

[0237] Reaction plate 420c is made of a compressible elastic material. For example, at least a portion of reaction plate 420c may be made of rubber. When reaction plate 420c is pressed by one or more of operating lever 12c and motor piston 28c, the reaction force generated by the pressing force is transmitted to the driver through operating lever 12c and constitutes a portion of the pedal force felt by the driver.

[0238] Reaction disc receptacle 422c is configured to accommodate at least a portion of reaction disc 420c in an accommodation space formed therein. When a first side of reaction disc receptacle 422c is pressed by one or more of operating rod 12c and motor piston 28c, a second side of reaction disc receptacle 422c presses push rod 13c.

[0239] The total pedal force provided to the driver may be determined as the sum of the pedal force generated by the reaction force to the compression force of the reaction plate 420 c and the pedal force generated by the reaction force to the compression force of the elastic body 17 c .

[0240] The electric control unit 50c generates a brake request signal based on a pedal stroke signal received from a pedal stroke sensor (not shown). The pedal request signal is an electrical signal that causes at least some of the plurality of wheel brakes (not shown) to generate a braking force.

[0241] The electric control unit 50c calculates the requested total braking force for braking the vehicle based on the pedaling signal. Furthermore, the electric control unit 50c determines whether to perform one or more of regenerative braking and hydraulic braking, and may apply regenerative braking force or control the electric booster unit 20c in another manner, depending on whether regenerative braking and / or hydraulic braking is performed. In this case, the requested total braking force may be the sum of the hydraulic braking force and the regenerative braking force. Multiple braking modes can be set. For example, the electric control unit 50c can set a hydraulic braking mode in which braking is performed only by hydraulic braking force, a regenerative braking mode in which braking is performed only by regenerative braking force, and a combined braking mode in which braking is performed by both hydraulic braking force and regenerative braking force, in order to brake the vehicle.

[0242] Figure 21A and Figure 21B Schematic diagram illustrating the relationship between the elastic reaction plate, operating rod, motor piston, and pedal force.

[0243] Figure 21A 1 is a schematic diagram illustrating the pedal force according to the displacement of the operating rod 12 c without changing the displacement of the reaction plate 420 c. Figure 21B 2 is a diagram illustrating the magnitude of the pedal force according to the pressure applied to the master cylinder 14 c when the relative displacement of the motor piston 28 c and the operating rod 12 c is constant.

[0244] Reference Figure 21A As can be seen, the pedal force increases when operating lever 12c moves toward reaction plate 420c, while the pedal force decreases when operating lever 12c moves in the opposite direction. However, when the difference between the displacement of operating lever 12c and the displacement of reaction plate 420c is within a predetermined range, the pedal force felt by the driver remains almost unchanged. This is because reaction plate 420c is made of an elastic material.

[0245] Reference Figure 21B , the difference between the displacement of the motor piston 28c and the displacement of the operating rod 12c is maintained at a constant level, and when the hydraulic pressure in the master cylinder 14c is increased by pressing the reaction plate 420, the pedal force felt by the driver increases according to the size of the hydraulic pressure in the master cylinder 14c rather than the displacement of the motor piston 28c and the operating rod 12c.

[0246] Figure 22 is a graph illustrating temporal relationships among the total pedal force, the pedal force of the elastic body, the pedal force of the reaction plate, the regenerative braking force, and the hydraulic braking force when the control unit stops regenerative braking while performing only regenerative braking during braking. Figures 23A to 23C This is an example Figure 22 The starting point and time point t 13 and t 14 Schematic diagram of the operation at .

[0247] exist Figure 22 、 Figure 24 、 Figure 26 and Figure 28 In the graph shown, L1 is the total pedal force, L2 is the pedal force of the elastic body 17c, L3 is the pedal force of the reaction plate 420c, L4 is the regenerative braking force, and L5 is the hydraulic braking force.

[0248] Figure 23A Shown in Figure 22 The operation at the starting point, Figure 23B Shown in Figure 22 Time point t 13 The operation at Figure 23C Shown in Figure 22 Time point t 14 Operation at.

[0249] Figure 22 The starting point is the point r where the driver begins to step on the pedal 11c. 11 , and a total pedal force L1 is generated at the starting point. Since the operating rod 12c is spaced apart from the central portion 423c of the reaction plate 420c, the pedal force L3 caused by the reaction force of the reaction plate 420c has not yet been generated. At the starting point where the driver starts to step on the pedal 11c and the time point t 10During the period between, only the pedal force L2 of the elastic body increases.

[0250] At time point t 10 and t 11 During the period between t and t, the pedal force L3 caused by the reaction force of the reaction plate 420c increases. The motor piston 28c moves toward the master cylinder 14c and presses the plate unit 42c, thereby forming a central portion 423c protruding from the center of the reaction plate 420c. The central portion 423c is at time point t 10 Contact with operating rod 12c. As the degree of depression of disc unit 42c increases, the reaction force of reaction disc 420c causes the pedal force to be provided to the driver via operating rod 12c. Therefore, the total pedal force L1 corresponding to the amount of depression of pedal 11c increases during this period. However, as motor piston 28c moves toward master cylinder 14c and elastic body 17c expands, the increase in pedal force of elastic body 17c may be less than the increase in total pedal force L1.

[0251] At the starting point and time t 11 No braking force is generated during the period between the two stops.

[0252] Time point t 11 and time point t 12 The period in between is a period in which the depression amount of the pedal 11 c increases and the corresponding braking force is generated. Figure 22 A case is shown where the electric control unit 50c starts the regenerative braking mode and brakes the vehicle, and during this period, no hydraulic braking force L5 is generated and the regenerative braking force L4 gradually increases.

[0253] Time point t 12 and time point t 13 The period between is the period during which the pedal 11c is depressed. During this period, the magnitude of the braking force required by the driver remains unchanged, so the regenerative braking force L4 is also maintained at a constant level. 13 ,like Figure 23B As shown, the motor piston 28c presses the disc unit 42c, so the displacement of the disc unit 42c is as shown in FIG. Figure 23B As shown in d 11 Move to d 12 , but does not move so as to generate hydraulic braking force L5.

[0254] Time t 13 and time t 14 The period between is the period when the electric control unit 50c stops the regenerative braking mode and starts the hydraulic braking mode. During this period, the regenerative braking force decreases, while the hydraulic braking force L5 increases with the reduced braking force. 13 and time t 14The period between is a period for increasing the hydraulic braking force L5. The braking system according to the third embodiment of the present disclosure drives the electric booster unit 20c to move the motor piston 28c from d 12 Move to d 13 To press the master cylinder 14c to 13 and t 14 The hydraulic braking force is generated during the period between 14 When, such as Figure 23C As shown, the displacement of the operating rod 12c is r 12 The position does not change, and only the displacement of the motor piston 28c changes.

[0255] When Figure 23B The pedal force felt by the driver is F1 and Figure 23C When the pedal force felt by the driver is F2, F1 and F2 satisfy Equation 1.

[0256] [Equation 1]

[0257] F1=P rd1 A+KX1

[0258] F2=P rd2 A+KX2

[0259] Among them, P rd1 yes Figure 23B The pressure applied by the reaction plate 420c to the operating rod 12c, A is Figure 23B The contact area between the reaction plate 420c and the operating rod 12c, K is the Young's modulus of the elastic body 17c, and X1 is Figure 23B The compression distance of the elastic body 17c, P rd2 is the pressure applied to the operating rod 12c by the reaction plate 420c, and X2 is Figure 23C The compression distance of the elastic body 17c.

[0260] The displacement of the operating rod 12c is maintained at this point r 12 , but the displacement of the motor piston 28c is Figure 23B and Figure 23C From point d 12 Move to point d 13 Therefore, X1>X2. Therefore, KX1>KX2.

[0261] Since the hydraulic braking force should be increased Figure 23CThe motor piston 28c should move further toward the master cylinder 14c to reduce the regenerative braking force. Since the motor piston 28c presses the reaction plate 420c more strongly while maintaining the displacement of the operating rod 12c, the center portion 423c of the reaction plate 420c made of elastic material protrudes further and the reaction plate 420c has a greater pressure (P rd1 <P rd2 In this case, even if the protrusion degree of the central portion 423c of the reaction plate 420c increases, the contact area between the central portion 423c and the operating rod 12c does not change.

[0262] Because P rd1 <P rd2 However, KX1>KX2, so F1≈F2. Therefore, even if the regenerative braking force decreases and the hydraulic braking force increases, the driver can feel the pedal force is not disconnected.

[0263] In the present disclosure, since the reaction plate 420 is made of an elastic material, and the degree of protrusion and the contact area with the operating rod 12c can be determined by the elasticity of the reaction plate 420c, the reaction plate 420c is preferably designed to satisfy F1≈F2, so that even when the regenerative braking force decreases and the hydraulic braking force increases, there is no difference between the pedal forces F1 and F2 felt by the driver.

[0264] Figure 24 Graph illustrating temporal changes in total pedal force, pedal force of the elastic body, pedal force of the reaction plate, regenerative braking force, and hydraulic braking force when the pedaling amount increases while the control unit stops regenerative braking in a case where only regenerative braking is performed during braking. Figures 25A to 25C This is an example Figure 24 The starting point and time point t 23 and t 24 Schematic diagram of the operation at .

[0265] Figure 25A Shown in Figure 24 The operation at the starting point, Figure 25B Shown in Figure 24 Time point t 23 The operation at Figure 25C Shown in Figure 24 Time point t 24 The brake system is in Figure 24 The starting point and time point t of the graph shown 23 Operations during the period between Figure 22 The starting point and time point t of the graph shown 13 The operations during the period between are similar and therefore will not be described below.

[0266] At time point t 23 , the electric control unit 50c stops the regenerative braking mode and starts setting the hydraulic braking mode. 23 and t 24 During the period between , the regenerative braking force L4 decreases and the hydraulic braking force L5 increases, but the driver increases the pedaling amount during this period, as shown in FIG. Figure 24 As shown, the requested hydraulic braking force L5 is greater than the existing maximum regenerative braking force L4.

[0267] The increase of hydraulic braking force L5 is Figure 24 Time point t 23 and t 24 The period between Figure 22 Time point t 13 and t 14 Greater in the period between.

[0268] According to the brake system of the third embodiment of the present disclosure, even in this case, the driver does not feel the disconnection of the pedaling. This will be described in detail below.

[0269] like Figure 25B and Figure 25C As shown, as the driver increases the pedaling amount, the displacement of the operating lever 12c changes from r 22 Move to r 23 The motor piston 28c is also driven by the electric booster unit 20c and presses the disc unit 42c, so that the disc unit 42c is displaced from d 22 Move to d 23 , while pressing the master cylinder 14c, thereby generating hydraulic pressure. As the pressure applied to the reaction plate 420c gradually increases, the central portion 423c protrudes further and the pressure applied to the operating rod 12c increases due to the corresponding reaction force. As a result, the magnitude of the pedal force L3 of the reaction force to the reaction plate 420c increases, but the elastomer 17c expands, so the magnitude of the pedal force L2 of the elastomer 17c decreases. The principle of equation 1 is fully applicable to this situation, so even if the hydraulic pressure in the master cylinder 14c changes, the driver will not feel the pedaling disconnection. That is, the motor piston 28c presses the reaction plate 420c, so the pedal force L3 of the reaction plate 420c increases. In addition, the motor piston 28c moves toward the master cylinder 14c, so the elastomer 17c expands and the pedal force L2 of the elastomer 17c decreases. Therefore, the driver will not feel the disconnection of the pedal force.

[0270] Figure 26 is a graph illustrating temporal relationships among the total pedal force, the pedal force of the elastic body, the pedal force of the reaction plate, the regenerative braking force, and the hydraulic braking force when the control unit stops regenerative braking while performing regenerative braking and hydraulic braking during braking. Figures 27A to 27C This is an example Figure 26 The starting point and time point t 34 and t 35 Schematic diagram of the operation at .

[0271] Figure 27A Shown in Figure 26 The operation at the starting point, Figure 27B Shown in Figure 26 Time point t 34 The operation at Figure 27C Shown in Figure 26 Time point t 35 Operation at.

[0272] Braking system in Figure 26 The starting point and time point t of the graph shown 32 The operation used to generate pedal force during the period between Figure 22 The starting point and time point t of the graph shown 12 The operations during the period between are similar and therefore will not be described below.

[0273] Figure 26 The starting point is the point at which the driver begins to step on the pedal 11c, and at which point the operating lever 12c is positioned at r 31 , and a total pedal force L1 is generated. Since the operating rod 12c is spaced apart from the central portion 423c of the reaction plate 420c, the pedal force L3 caused by the reaction force of the reaction plate 420c is not generated.

[0274] At the time point t when the driver steps on the pedal 11 c 30 and t 31 During this period, the pedal force L2 generated by the compression of the elastic body 17c and the contact of the reaction plate 420c increases.

[0275] Time point t 31 and time point t 32 The period in between is a period during which the depression amount of the pedal 11 c increases and a corresponding braking force is generated. Figure 26 A case is shown where the electric control unit 50c first starts the regenerative braking mode and brakes the vehicle, and during this period, no hydraulic braking force L5 is generated and the regenerative braking force L4 gradually increases.

[0276] Time point t 32 and t 33The period between is the period during which the electric control unit 50c determines that the hydraulic braking mode should be started, for example, the driver should further step on the pedal 11c and generate a hydraulic braking force L5. During this period, the regenerative braking force L4 is maintained, but the electric booster unit 20 is driven and presses the motor piston 28, thereby increasing the hydraulic pressure supplied to multiple wheel brakes (not shown). During this process, the operating rod 12c moves further toward the master cylinder 14c, thereby pressing the protruding central portion 423c of the reaction plate 420c. The operating rod 12c contacts the central portion 423c of the reaction plate 420c, so that the driver additionally feels the pedal force L3 of the reaction plate 420c. In this case, the total pedal force L1 is the sum of the pedal force L2 of the elastic body 17c and the pedal force L3 of the reaction plate 420c.

[0277] Time point t 33 and time point t 34 The period between is the period during which the pedal 11c is depressed. During this period, since the magnitude of the braking force requested by the driver remains unchanged, the regenerative braking force L4 and the hydraulic braking force L5 are also maintained at a constant level. At time point t 34 ,like Figure 27B As shown, the motor piston 28c presses the disc unit 42c, so the displacement of the disc unit 42c moves to Figure 27B d shown in 32 The motor piston 28c is pressed, and the center portion 423c of the reaction plate 420c is larger than the center portion 423c of the reaction plate 420c. Figure 27A During this period, as the driver increases the amount of depression to form the hydraulic braking force L5, the displacement of the operating rod 12c moves to r 32 .

[0278] Time point t 34 and time point t 35 The period in between is a period during which the electric control unit 50c stops the regenerative braking mode and increases the hydraulic braking force by the reduced regenerative braking force.

[0279] The brake system according to the third embodiment of the present disclosure drives the electric booster unit 20c to move the motor piston 28c from d 32 Move to d 33 To further press the master cylinder 14c to 34 and t 35 Increase the hydraulic braking force during the period between 35 When, such as Figure 27C As shown, the displacement of the operating rod 12c is r 32The total pedal force L1 does not change, and only the displacement of the motor piston 28c changes. Since the operating rod 12c remains in contact with the reaction plate 420c, the total pedal force L1 is affected by the pedal force L2 of the elastomer 17c and the pedal force L3 of the reaction plate 420c. However, even if affected by the pedal force L3 of the reaction plate 420c, the magnitude of the total pedal force L1 does not change as described with reference to Equation 1. That is, the motor piston 28c presses the reaction plate 420c, so the pedal force L3 of the reaction plate 420c increases. In addition, the motor piston 28c moves toward the master cylinder 14c, so the elastomer 17c expands and the pedal force L2 of the elastomer 17c decreases. Therefore, the driver does not feel a disconnection in the pedal force.

[0280] Figure 28 It is a graph illustrating the relationship between the total pedal force, the pedal force of the elastic body, the pedal force of the reaction plate, the regenerative braking force and the hydraulic braking force over time when the pedaling amount increases while the control unit performs both regenerative braking and hydraulic braking during braking. Figures 29A to 29C This is an example Figure 28 The starting point and time point t 44 and t 45 Schematic diagram of the operation at .

[0281] Figure 29A Shown in Figure 28 The operation at the starting point, Figure 29B Shown in Figure 28 Time point t 44 The operation at Figure 29C Shown in Figure 28 Time point t 45 The brake system is in Figure 28 The starting point and time point t of the graph shown 44 Operations during the period between Figure 26 The starting point and time point t of the graph shown 34 The operations during the period between are similar and therefore will not be described below.

[0282] At this time point t 44 , the electric control unit 50c drives the electric booster unit 20c to stop the regenerative braking mode and increase the hydraulic braking force L5. 44 and t 45 During the period between , the regenerative braking force L4 decreases and the hydraulic braking force L5 increases, but the driver increases the pedaling amount during this period, as shown in FIG. Figure 28 As shown, the requested hydraulic braking force L5 is greater than the existing maximum regenerative braking force L4.

[0283] The increase of hydraulic braking force L5 is Figure 28At time points t4 and t 45 The period between Figure 26 Time point t 34 and t 35 Greater in the period between.

[0284] According to the brake system of the third embodiment of the present disclosure, even in this case, the driver does not feel the disconnection of the pedaling.

[0285] like Figure 29B and Figure 29C As shown in FIG, as the driver increases the pedaling amount, the displacement of the operating lever 12c changes from r 42 Move to r 43 The motor piston 28c is also driven by the electric booster unit 20c and presses the disc unit 42c, so that the disc unit 42c is displaced from d 42 to d 43 While moving, the master cylinder 14c is pressed, thereby generating hydraulic pressure. FIG. 29B to FIG. 29C During the driving, the operating rod 12c is kept in contact with the center portion 423c of the reaction plate 420c, but the pedal force felt by the driver hardly changes, as described with reference to the equation. Therefore, even if the hydraulic pressure in the master cylinder 14c changes, the driver does not feel the disconnection of the pedaling.

[0286] Figure 30 is a flowchart of a method of controlling a brake system according to a third embodiment of the present disclosure. Figure 30 The flowchart is a description of some of the braking methods in the plurality of braking methods, and the electric control unit 50c does not necessarily include Figure 30 and may include algorithms that include Figure 30 A variety of braking algorithms. Figure 30 This is a flowchart constructed under the assumption that the regenerative braking unit is driven, wherein the electric control unit 50c may include other methods of braking the vehicle using only the hydraulic braking force.

[0287] The electric control unit 50c receives a brake pedal signal (S10c). That is, the electric control unit 50c receives a signal from the brake pedal 11c to check whether the driver steps on the pedal 11c. When the brake pedal signal is not received, the electric control unit 50c determines that no braking situation occurs and does not execute the braking operation. Figure 30 control processing.

[0288] When the brake signal is received, the electric control unit 50c calculates the requested total braking force (S20c). The requested total braking force is determined based on the driver's depression amount on the pedal 11c and may be determined based on additional determinations by the electric control unit 50c with the autonomous driving function. When the driver depresses the pedal 11c, the electric control unit 50c calculates the requested total braking force for braking the vehicle based on the depression amount of the pedal 11c measured by the pedal travel sensor (not shown).

[0289] The electric control unit 50c calculates the requested regenerative braking force based on the requested total braking force (S30c). After calculating the requested regenerative braking force, the electric control unit 50c drives the regenerative brake unit (not shown) based on the calculated requested regenerative braking force (S40c).

[0290] When the regenerative braking unit (not shown) is driven, the electric control unit 50c determines whether to stop the regenerative braking (S50c). The electric control unit 50c can determine to stop the regenerative braking by itself, or can use a regenerative braking stop signal received from the outside to determine whether to stop the regenerative braking.

[0291] When it is determined that the regenerative braking is stopped, the electric control unit 50c calculates the requested hydraulic braking force due to the stop of the regenerative braking (S60c). When the electric control unit 50c stops the regenerative braking mode, the regenerative braking force decreases, so the electric control unit 50c senses the magnitude of the regenerative braking force and calculates the requested hydraulic braking force for compensation corresponding to the sensed braking force.

[0292] The electric control unit 50c calculates the requested displacement of the motor piston 28c according to the requested hydraulic braking force (S70c).The requested displacement of the motor piston 28c is determined based on the displacement of the motor piston 28c at the time when the electric control unit 50c starts to stop regenerative braking.

[0293] The electric control unit 50c drives the electric booster unit 20c to move the motor piston 28c by the requested displacement (S80c). The electric control unit 50c drives the electric booster unit 20c to move the motor piston 28c toward the master cylinder 14c, thereby pressing the reaction plate 420c. In this case, the reaction plate 420c is made of an elastic material, and the motor piston 28c can contact the outer edge of the reaction plate 420c.

[0294] When the motor piston 28c moves by the requested displacement, the electric control unit 50c performs control using the elastic body 17c and the reaction plate 420c so that the magnitude of the pedal force felt by the driver is fully maintained (S90c).

[0295] In this case, the first end of the elastic body 17c contacts the brake pedal 11c and the second end contacts a portion of the electric booster unit 20c, so the driver's pedal force can be reduced when the motor piston 28c moves toward the master cylinder 14c.

[0296] As motor piston 28c presses reaction plate 420c, a central portion 423c of reaction plate 420c may protrude toward operating rod 12c. When the protruding reaction plate 420c contacts operating rod 12c, it provides a reaction force to operating rod 12c. This reaction force constitutes a portion of the pedal force felt by the driver. According to the present disclosure, as described with reference to the equation, even when reaction plate 420c and operating rod 12c are in contact, there is no disconnection in pedaling during periods of reduced regenerative braking force and increased hydraulic braking force.

[0297] The method ends the algorithm after completing S90c.

[0298] Figures 22 to 30 The braking logic is an example, and the present disclosure does not reduce the driver's pedal disconnection by using only the braking logic shown in the figure, and has the effect that the present disclosure can prevent the driver's pedal disconnection by using any braking logic.

[0299] CROSS-REFERENCE TO RELATED APPLICATIONS

[0300] This application claims priority to and the benefit of Korean Patent Application No. 10-2021-0023791, filed on February 23, 2021, and Korean Patent Application No. 10-2021-0059777, filed on May 10, 2021, the disclosures of which are hereby incorporated by reference in their entirety.

Claims

1. A braking system configured to perform cooperative braking in a braking situation of a vehicle, wherein both regenerative braking and hydraulic braking are performed in the cooperative braking, the braking system comprising: master cylinder; a reaction plate made of an elastic material and configured to press the master cylinder; an electric booster comprising a motor, a gear device, a motor piston, and a screw shaft, the gear device being configured to transmit torque of the motor to the screw shaft, the motor piston being configured to press at least a portion of the reaction plate, the screw shaft being configured to press the motor piston, and the electric booster being configured to press the master cylinder by adjusting displacement of the motor piston; a rod assembly including an operating rod whose displacement is adjusted according to the amount of depression of the brake pedal, and an elastic body whose first end contacts a portion of the operating rod and whose second end contacts at least a portion of the electric booster; a push rod at least partially inserted into the master cylinder, the push rod reciprocating in the master cylinder along the longitudinal direction of the master cylinder and pressing brake fluid stored in the master cylinder when moving forward; a return spring disposed in the master cylinder and compressed or expanded by the reciprocating motion of the push rod; as well as a control unit configured to control the electric booster and perform control to brake the vehicle using one or more of the regenerative braking and the hydraulic braking, Wherein, when the control unit brakes the vehicle by performing at least the regenerative braking of the regenerative braking and the hydraulic braking, the control unit drives the electric booster to press the reaction plate when the regenerative braking is stopped, thereby maintaining the magnitude of the pedal force by using the elastomer and the reaction plate of the elastic material.

2. The braking system according to claim 1, wherein: The elastic body is in contact with the motor piston or the screw shaft of the electric booster.

3. The braking system according to claim 2, wherein: The screw shaft includes a first shaft configured to rotate and a second shaft configured to press the motor piston by converting the rotational motion of the first shaft into a linear motion, and The elastic body is in contact with the second shaft.

4. The braking system according to claim 1, wherein: The gear device includes a first gear, a second gear, and a third gear, the first gear receiving the torque transmitted from the motor and transmitting the torque to the second gear, the second gear transmitting the torque received from the first gear to the third gear, and the third gear transmitting the torque received from the second gear to the screw shaft.

5. The braking system according to claim 1, wherein: The operating rod is configured to compress a central portion of the reaction plate, and the motor piston is configured to compress an outer periphery of the reaction plate.

6. The braking system according to claim 5, wherein: If the motor piston compresses the reaction plate, the central portion of the reaction plate protrudes toward the operating rod according to a degree of compression, thereby forming a protruding portion.

7. The braking system according to claim 6, wherein: When the protrusion abuts the operating rod as the brake pedal is pressed, the pressure applied from the reaction plate to the operating rod increases as the pressure applied by the motor piston on the reaction plate increases, and at the same time, the contact area between the reaction plate and the operating rod decreases.

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