Actuation assembly for a braking system of the brake-by-wire type, braking system, method

Abstract

The subject matter of the present invention is an actuation assembly (1) for a braking system (100) of the brake-by-wire type, said assembly (1) being configured to be connected to a brake pedal or lever (101), said assembly (1) comprising a brake master cylinder (2), wherein the brake master cylinder (2) comprises at least one float (4) and a cylinder (5), wherein the cylinder (5) defines a cavity or housing compartment (6) adapted to contain a working fluid, wherein the at least one float (4) is movable in the cavity (6) at least by an actuation of the brake pedal (101), wherein the cylinder (5) delimits a supply hole (7), at least one tank (9) adapted to contain a stock of said working fluid, wherein said at least one tank (9) is fluidically connected or connectable to the cavity (6) by means of a supply branch (21) connected to the supply hole (7); wherein the cylinder (5) with the float (4) defines a pressure chamber (10) in the cavity (6), wherein the float (4) is configured to move forward in the cavity (6) over an idle float stroke (X1) obstructing the supply hole (7), fluidically isolating the pressure chamber (10) from the supply hole (7) so as to pressurize the working fluid in the pressure chamber (10), a braking feel simulator device (3) comprising at least one absorber (11), wherein the at least one absorber (11) is fluidically connected or connectable to the pressure chamber (10) by means of an absorber branch (13) along which a first electrically controllable shut-off valve or first valve (19) is arranged, wherein the at least one absorber (12) is configured to receive the working fluid from the pressure chamber (10) applying a reaction force to the brake pedal (101) opposing the actuation of the brake pedal (101) when the first valve (19) is open, wherein said at least one tank (9) is fluidically connected or connectable to the pressure chamber (10) by means of a refilling branch (14) along which a second electrically controllable shut-off valve or second valve (20) is arranged, wherein the refilling branch (14) is configured to transfer the working fluid from the pressure chamber (10) to the at least one tank (9) when the second valve (20) is open, wherein the assembly (1) comprises: a pressure sensor (12) configured to detect a working pressure of the pressurized working fluid in the pressure chamber (10) during the actuation of the brake pedal or lever (101), a third electrically controllable shut-off valve or third valve (21) arranged along the supply branch (17), wherein the supply branch (17) is configured to fluidically connect the cavity (6) and / or the pressure chamber (10) to the at least one tank (9) when the third valve (21) is open and until the float (4) is moved forward over the idle float stroke (X1) by actuating the brake pedal (101), wherein the pressure sensor (12) is operatively connectable to a control and processing unit (18) to control, either by wire or electrically, an actuation of a braking device (102), wherein the first valve (19), the second valve (20), and the third valve (21) are operatively connectable to the control and processing unit (18) to control the opening and / or closing of the first valve (19), the second valve (20), and the third valve (21) so that when the first valve (19) is open, the second valve (20) is closed and the third valve (21) is open, once the float (4) is moved forward over the idle float stroke (X1) by actuating the brake pedal (101), the at least one absorber (12) applies a reaction force to the brake pedal (101) opposing the actuation of the brake pedal (101) and the control and processing unit (18) controls, either by wire or electrically, the actuation of the braking device (102) based on the working pressure detected by the pressure sensor (12), and so that when the first valve (19) is open, the second valve (20) is open and the third valve (21) is closed, the float (4) is positionable in a selected position (XP) in the cavity (6) by actuating the

Description

"Actuation assembly for a braking system of the brake-by-wire type, braking system, method" ***DESCRIPTION

[0001] . Field of the invention

[0002] . The present invention relates to an actuation assembly for a braking system of theBrake By Wire ("BBW') type, as well as to a braking system of the BBW type, and to a method for actuating the braking system.

[0003] . Prior art

[0004] . In BBW-type braking systems of vehicles with two or more wheels actuatable by a driver by means of a brake pedal or lever, the force and displacement applied to the brake pedal or lever by the driver are decoupled from the resulting braking force which is applied by at least one braking device to the respective wheel of the vehicle.

[0005] . In BBW braking systems, the force and displacement applied by the driver to the brake pedal or lever are transduced into an electrical signal which is processed by a control and processing unit to control the actuation of the callipers of the braking system, for example by hydraulically or electrically actuating the braking devices.

[0006] . BBW braking systems are known comprising a braking feel simulator device configured to simulate the feel and stiffness of a brake pedal or lever of conventional hydraulic braking systems, and thus emulate the “stiffness curve”. The term “stiffness curve” refers to the relationship between the displacement of the brake pedal or lever along its stroke and the corresponding reaction force exerted by the simulator device on the brake pedal or lever, and hence by the brake pedal or lever on the driver.

[0007] . It is also known to provide in BBW braking systems a brake master cylinder connected to the brake pedal or lever, wherein the brake master cylinder is hydraulically connected to the braking feel simulator device via a first branch along which a first electrically controllable shut-off valve is arranged. In a by-wire condition, the first electrically controllable shut-off valve is open such that the working fluid pressurized by the brake master cylinder acts on the simulator device, and by detecting a current position of the piston and / or directly or indirectly a force applied on the piston, it is possible to actuate the at least one braking device by means of motor means.

[0008] . Usually, in BBW braking systems, the brake pedal or lever acts on a float movable in a cavity of a cylinder of the brake master cylinder in fluid connection with a tank containing a working fluid, wherein the float, by advancing and once the fluid connection with the fluid tank is interrupted, in a by-wire configuration, acts on the fluid which, passing through the first branch, in turn acts on an absorber of the braking feel simulator device arranged downstream of the brake master cylinder so as to simulate the braking feel on the pedal. Such solutions are known, for example, from documentEP3630559 in the name of the Applicant.

[0009] . The known solutions provide to arrange the absorber downstream of the brake master cylinder, forming two separate chambers for the fluid: a pressure chamber of the brake master cylinder and a simulator chamber of the absorber, adapted to receive the fluid from the pressure chamber via a connecting branch.

[0010] . In some known solutions, the absorber and the brake master cylinder are implemented in a single assembly of brake master cylinder and pedal simulator, with the brake master cylinder and the absorber connected via a first branch either in line or transversely with respect to each other.

[0011] . Although satisfactory, the known solutions may result in low versatility, as these types of actuators are actuatable only in the traditional way by applying a reaction force along a pedal stroke.

[0012] . Furthermore, the known solutions are bulky, as the brake pedal is always provided, both in the configuration with suspended brake pedal and in the configuration with floor-mounted pedal, in an area that may interfere with driving comfort for a driver.

[0013] . Therefore, there is a need in the field to implement actuation assemblies for BBW-type braking systems that are highly versatile and that can allow a reduction in space requirements within the passenger compartment of a vehicle.

[0014] . Solution

[0015] . The present invention aims to provide an actuation assembly for a BBW-type braking system, as well as a BBW-type braking system, and a method of actuating the braking system that allow overcoming at least some of the drawbacks identified in the prior art.

[0016] . These and other objects are achieved by means of an actuation assembly, a braking system provided with such assembly, and a method according to the independent claims.

[0017] . Some advantageous embodiments are the subject of the dependent claims.

[0018] . Thanks to the proposed solutions, it is possible to provide a more versatile actuation assembly, allowing the driver to actuate the brake pedal or lever according to a first mode or braking simulator mode with damping and / or opposition of the pedal stroke, and also according to a second mode or tactile mode with the pedal stroke substantially prevented or greatly reduced, the pedal being positioned in a selected position. Thanks to the tactile mode, it is possible to change the position of the brake pedal or lever inside the vehicle passenger compartment according to the driver’s needs, both in the configuration with suspended brake pedal and in the configuration with floor-mounted brake pedal, thus reducing the bulk of the actuation assembly inside the compartment as desired by the driver.

[0019] . Thanks to the proposed solutions, it is possible to provide an actuation assembly usable in autonomous vehicles, avoiding the constant bulk of the brake pedal or lever which preventsthe driver from assuming any relaxed leg position while driving.

[0020] . Figures

[0021] . Further features and advantages of the actuation assembly, of the braking system provided with such assembly, and of the method will appear from the description below of its preferred embodiments, provided by way of non-limiting example, with reference to the accompanying figures in which:

[0022] . - Figure 1 shows a schematic representation of a braking system according to the present invention, wherein the braking system comprises a brake master cylinder comprising a float, wherein the float is housed in the cylinder, a tank for a working fluid or brake fluid, a pressure sensor, an absorber configured to oppose the stroke of the float by selectively damping it, a control and processing unit or electronic unit configured to control the selective opening or closing of shut-off valves between the brake master cylinder and the tank and between the brake master cylinder and the absorber, so as to selectively choose between a first actuation mode, wherein the absorber opposes the stroke of the float by damping its advancement and simulating a braking feel, and a second actuation mode, wherein the second actuation mode comprises a float positioning step, wherein a user positions the float in a selected position along the float stroke between the rest position and the end stroke position, wherein the second actuation mode includes a locking step, wherein the float position is hydraulically locked in the selected position, and the pedal stroke is substantially limited to the sole compression of the working fluid in the brake master cylinder;

[0023] . - Figure 2 shows a schematic representation of a braking system according to the present invention, wherein with respect to the braking system of figure 1 , a hydraulic connection is also provided between the brake master cylinder and the braking device so that in the event of an electrical system failure, a backup actuation mode is provided, wherein the brake master cylinder directly hydraulically actuates the braking device.

[0024] . Description of some preferred embodiments

[0025] . In accordance with a general embodiment, an actuation assembly for a braking system 100 of the brake-by-wire type is denoted by the reference number 1. In one embodiment, the actuation assembly is a brake master cylinder and pedal simulator assembly. Said assembly 1 is configured to be connected to a brake pedal or lever 101.

[0026] . The assembly 1 comprises a brake master cylinder 2. The brake master cylinder 2 comprises at least one float 4 and a cylinder 5, wherein the cylinder 5 defines a cavity or housing compartment 6 suitable for containing a working fluid, wherein the at least one float 4 is movable in the cavity 6 at least by an actuation of the brake pedal 101. The cylinder 5 delimits a supply hole 7.

[0027] . The assembly 1 comprises at least one tank 9 configured to contain a stock of said working fluid. Said at least one tank 9 is fluidically connected or connectable to the cavity 6 by meansof a supply branch 21 connected to the supply hole 7. The cylinder 5 with the float 4 defines a pressure chamber 10 in the cavity 6. The float 4 is configured to move forward in the cavity 6 over an idle float stroke X1 , obstructing the supply hole 7, fluidically isolating the pressure chamber 10 from the supply hole 7 so as to pressurize the working fluid in the pressure chamber 10.

[0028] . The assembly 1 comprises a braking feel simulator device 3 comprising at least one absorber 11. The at least one absorber 11 is fluidically connected or connectable to the pressure chamber 10 by means of an absorber branch 13 along which a first electrically controllable shut-off valve or first valve 19 is arranged.

[0029] . The at least one absorber 12 is configured to receive the working fluid from the pressure chamber 10, applying a reaction force to the brake pedal 101 opposing the actuation of the brake pedal 101 when the first valve 19 is open.

[0030] . The at least one tank 9 is fluidically connected or connectable to the pressure chamber 10 by means of a refilling branch 14 along which a second electrically controllable shut-off valve or second valve 20 is arranged. The refilling branch 14 is configured to transfer the working fluid from the pressure chamber 10 to the at least one tank 9 when the second valve 20 is open.

[0031] . The assembly 1 comprises a pressure sensor 12 configured to detect a working pressure of the pressurized working fluid in the pressure chamber 10 during the actuation of the brake pedal or lever 101.

[0032] . The assembly 1 comprises a third electrically controllable shut-off valve or third valve 21 arranged along the supply branch 17, wherein the supply branch 17 is configured to fluidically connect the cavity 6 and / or the pressure chamber 10 to the at least one tank 9 when the third valve 21 is open and until the float 4 is moved forward over the idle float stroke X1 by actuating the brake pedal 101.

[0033] . The pressure sensor 12 is operatively connectable to a control and processing unit 18 to control, either by wire or electrically, an actuation of a braking device 102.

[0034] . Advantageously, the first valve 19, the second valve 20, and the third valve 21 are operatively connectable to the control and processing unit 18 to control the opening and / or closing of the first valve 19, the second valve 20, and the third valve 21 so that when the first valve 19 is open, the second valve 20 is closed and the third valve 21 is open, once the float 4 is moved forward over the idle float stroke X1 by actuating the brake pedal 101 , the at least one absorber 12 applies a reaction force to the brake pedal 101 opposing the actuation of the brake pedal 101 and the control and processing unit 18 controls, either by wire or electrically, the actuation of the braking device 102 based on the working pressure detected by the pressure sensor 12.

[0035] . Advantageously, the first valve 19, the second valve 20, and the third valve 21 are operatively connectable to the control and processing unit 18 to control the opening and / or closing ofthe first valve 19, the second valve 20, and the third valve 21 so that when the first valve 19 is open, the second valve 20 is open and the third valve 21 is closed, the float 4 is positionable in a selected position XP in the cavity 6 by actuating the brake pedal 101 without pressurizing the working fluid in the pressure chamber 10, avoiding the control and processing unit 18 from controlling, either by wire or electrically, the actuation of the braking device 102.

[0036] . Advantageously, the first valve 19, the second valve 20, and the third valve 21 are operatively connectable to the control and processing unit 18 to control the opening and / or closing of the first valve 19, the second valve 20, and the third valve 21 so that when the first valve 19 is closed, the second valve 20 is closed and the third valve 21 is closed, the float 4 is fluidically locked in the cavity 6 in the selected position XP and the control and processing unit 18 controls, either by wire or electrically, the actuation of the braking device 102 based on the working pressure detected by the pressure sensor 12. Thanks to the provision of the absorber integrated into the brake master cylinder, it is possible to connect the absorber directly to the brake pedal 3, so as to provide an immediate reaction force on the pedal, without idle strokes lacking reaction forces during a pedal actuation. Furthermore, thanks to the provision of the absorber interposed between the pedal and the float, it is possible to immediately actuate a forward movement of the float and at the same time damp and oppose the advancement of the pedal.

[0037] . Thanks to the first valve, the second valve and the third valve selectively controllable in opening and closing, it is possible to allow a user to use the actuation assembly according to a first mode in which, upon actuation of the brake pedal or lever, a braking simulator opposes the stroke of the float, simulating a braking feel, or a user may select a selected position XP, for example a preferred selection, and lock the brake pedal or lever and / or the float in the selected position XP and actuate the actuation assembly with the float locked. In this way, it is possible both to choose, at the user's or driver's discretion, an actuation mode of the brake master cylinder, and at the same time to position and lock the float in a preferred position, thereby varying the bulk of the assembly inside the passenger compartment, in particular the bulk of the brake lever or pedal. For example, the float may be locked in a rest position X0. Or the float may be locked in any forward position between the rest position and an end stroke position beyond which the float is prevented from advancing. Or again, the float may be locked in the end stroke position, maximally reducing the bulk of the brake pedal in the passenger compartment of the vehicle.

[0038] . In one embodiment, the assembly comprises the brake pedal or lever 101 connected to the float 4. In one embodiment, the brake pedal 101 moves integrally with the float 4, so that when the float 4 is locked in the selected position, the pedal is also locked in a respective selected position.

[0039] . In one embodiment, the braking feel simulator device 3 is configured to contain the working fluid with fluid continuity inside the absorber 12 and the at least one tank 9.

[0040] . In one embodiment, the absorber 12 is integrated in said brake master cylinder 2 downstream of said float 4.

[0041] . In one embodiment, the pressure sensor is positioned in the pressure chamber 10.

[0042] . In one embodiment, the pressure sensor 12 is fluidically connected to the pressure chamber 10 via a sensor branch 23.

[0043] . In one embodiment, the assembly 1 comprises a primary branch 15. In one embodiment, the cylinder 5 delimits an outlet hole 7, wherein the primary branch 15 is fluidically connected to the outlet hole 7, and wherein the refilling branch 14 and the absorber branch 13 are fluidically connected to the primary branch 15.

[0044] . In one embodiment, the assembly 1 comprises a braking device branch 16. In one embodiment, the braking device branch 16 is configured to fluidically connect at least one braking device 102 to the pressure chamber 10.

[0045] . In one embodiment, the assembly 1 comprises a fourth electrically controllable shut-off valve or fourth valve 22 arranged along the braking device branch 16.

[0046] . In one embodiment, the fourth valve 22 is operatively connectable to the control and processing unit 18 to control the opening and / or closing of the fourth valve 22, so that when the fourth valve 22 is open, the first valve 19 is closed, the second valve 20 is closed and the third valve 21 is open, the braking device 102 is fluidically controllable by actuating the brake pedal 101.

[0047] . In one embodiment, the fourth valve 22 is a normally open valve.

[0048] . In one embodiment, the third valve 21 is a normally open valve.

[0049] . In one embodiment, the second valve 20 is a normally closed valve.

[0050] . In one embodiment, the first valve 19 is a normally closed valve.

[0051] . In one embodiment, the fourth valve 22 is a normally open valve, the third valve 21 is a normally open valve, the second valve 20 is a normally closed valve, the first valve 19 is a normally closed valve so that in case of electrical failure, the braking device 102 is fluidically controllable by actuating the brake pedal 101 in a hydraulic backup mode.

[0052] . In one embodiment, the pressure chamber 10 avoids being fluidically connected to the braking device 102, the first valve 19 is a normally open valve, the second valve 20 is a normally closed valve, the third valve 21 is a normally open valve.

[0053] . The present invention also relates to a braking system 100 of the brake-by-wire type for a vehicle.

[0054] . The braking system 100 comprises an actuation assembly 1 according to any of the previously described embodiments. In one embodiment, the actuation assembly is connected to a brake pedal or lever 101.

[0055] . The braking system 100 comprises at least one braking device 101 operativelyconnected to the actuation assembly 1.

[0056] . The braking system 100 comprises a control and processing unit 18 operatively connected to said actuation assembly 1 and to motor means for actuating said at least one braking device 102.

[0057] . The control and processing unit 18 is programmed so as to actuate the braking device 102 by the motor means as a function of the actuation of the assembly 1 through the brake lever or pedal 101 in an operating by-wire condition, wherein in the operating by-wire condition a hydraulic connection between the actuation assembly 1 and the braking device 102 is avoided. In one embodiment, the control and processing unit 18 is programmed to actuate the braking device 102 by the motor means based on the working pressure Pw detected by the pressure sensor 12.

[0058] . In one embodiment, the braking device 102 is hydraulically connected to the actuation assembly 1, in particular to the brake master cylinder 2.

[0059] . The present invention also relates to a method for actuating a braking system 100 of the brake-by-wire type.

[0060] . The braking system 100 comprises an actuation assembly 1 and a braking device 101 operatively connected to the actuation assembly 1 and actuable in an operating by-wire condition by a control and processing unit 18, wherein in the operating by-wire condition a hydraulic connection between the actuation assembly 1 and the braking device 102 is avoided.

[0061] . The actuation assembly 1 comprises a brake master cylinder 2, at least one tank 9, a braking feel simulator device 3, and at least one pressure sensor 12. The brake master cylinder 2 comprises at least one float 4 and a cylinder 5, wherein the cylinder 5 defines a cavity or housing compartment 6 suitable for containing a working fluid, wherein the at least one float 4 is movable in the cavity 6 at least by actuating the brake pedal 101 , wherein the cylinder 5 delimits a supply hole 7. The at least one tank 9 is configured to contain a stock of said working fluid. Said at least one tank 9 is fluidically connected or connectable to the cavity 6 by means of a supply branch 21 connected to the supply hole 7; wherein the cylinder 5 with the float 4 defines a pressure chamber 10 in the cavity 6, wherein the float 4 is configured to move forward in the cavity 6 over an idle float stroke X1, obstructing the supply hole 7, fluidically isolating the pressure chamber 10 from the supply hole 7 so as to pressurize the working fluid in the pressure chamber 10, wherein the braking feel simulator device 3 comprises at least one absorber 11 , wherein the at least one absorber 11 is fluidically connected or connectable to the pressure chamber 10 by means of an absorber branch 13, wherein the pressure sensor 12 is configured to detect a working pressure of the pressurized working fluid in the pressure chamber 10 during the actuation of the brake pedal or lever 101.

[0062] . The braking system 100 is actuable, in the operating by-wire condition, at least according to a first actuation mode and according to a second actuation mode.

[0063] . The method includes a step of selecting the actuation mode, wherein one of the first actuation mode and the second actuation mode is selected, for example by means of a mode selector.

[0064] . The method provides that by selecting the first actuation mode, upon actuation of the brake pedal 101 , the float 4 moves forward from a float rest position X0 at least over the idle float stroke X1, and the at least one absorber 12 receives the working fluid from the pressure chamber 10, applying a reaction force to the brake pedal 101 opposing the actuation of the brake pedal 101 , and the pressure sensor 12 detects the working pressure Pw of the working fluid in the pressure chamber 10, and the braking device 102 is actuated by wire based on the detected working pressure Pw.

[0065] . The method provides that by selecting the second actuation mode, a positioning step and a locking step are included.

[0066] . In the positioning step, the float 4 is positionable in a selected position XP in response to the actuation of the brake pedal 101, wherein the selected position XP is selected from the rest position X0 and any forward position in the cavity 6, avoiding actuating by wire the braking device 102 based on the working pressure Pw detected during the positioning step.

[0067] . In the step of locking the selected position of the float 4, the float 4 is hydraulically locked in the selected position XP.

[0068] . The method provides that once the float 4 has been hydraulically locked in the selected position XP, upon actuation of the brake pedal 101 the working fluid in the pressure chamber 10 applies a reaction force to the brake pedal 101 opposing the actuation of the brake pedal 101 , and the pressure sensor 12 detects the working pressure Pw of the working fluid in the pressure chamber 10, and the braking device 102 is actuated by wire based on the detected working pressure Pw.

[0069] . In one mode of operation, in the positioning step, the float 4 is positionable in the selected position in response to the actuation of the brake pedal 101 , avoiding pressurizing the working fluid in the pressure chamber 10.

[0070] . In one mode of operation, the step of selecting the actuation mode, in the absence of a selection by the user, includes an automatic selection of the first actuation mode.

[0071] . In one mode of operation, the actuation assembly 1 is an actuation assembly according to any one of the previously described embodiments.

[0072] . In one mode of operation, the braking system 100 is a braking system according to any one of the previously described embodiments.

[0073] . In one mode of operation, the actuation assembly 1 comprises a first electrically controllable shut-off valve or first valve 19 arranged along the absorber branch 13.

[0074] . In one mode of operation, said at least one tank 9 is fluidically connected or connectable to the pressure chamber 10 by means of a refilling branch 14 along which a secondelectrically controllable shut-off valve or second valve 20 is arranged.

[0075] . In one mode of operation, the actuation assembly 1 comprises a third electrically controllable shut-off valve or third valve 21 arranged along the supply branch 17.

[0076] . In one mode of operation, the method provides that by selecting the first actuation mode, the first valve 19, the second valve 20, and the third valve 21 are controlled so that the first valve 19 is open, the second valve 20 is closed and the third valve 21 is open so that upon actuation of the brake pedal 101 , once the float 4 has been moved forward over the idle float stroke X1 by actuating the brake pedal 101 , the at least one absorber 12 applies a reaction force to the brake pedal 101 opposing the actuation of the brake pedal 101 and the control and processing unit 18 controls, either by wire or electrically, the actuation of the braking device 102 based on the working pressure detected by the pressure sensor 12.

[0077] . In one mode of operation, the method provides that by selecting the second actuation mode, during the positioning step, the first valve 19, the second valve 20, and the third valve 21 are controlled so that the first valve 19 is open, the second valve 20 is open and the third valve 21 is closed, so that the float 4 is positionable in a selected position XP in the cavity 6 by actuating the brake pedal 101 without pressurizing the working fluid in the pressure chamber 10, avoiding the control and processing unit 18 from controlling, either by wire or electrically, the actuation of the braking device 102. In one mode of operation, the method provides that during the locking step, the first valve 19, the second valve 20, and the third valve 21 are controlled so that the first valve 19 is closed, the second valve 20 is closed and the third valve 21 is closed, so that the float 4 is fluidically locked in the cavity 6 in the selected position XP and the control and processing unit 18 controls, either by wire or electrically, the actuation of the braking device 102 based on the working pressure detected by the pressure sensor 12.LIST OF REFERENCES1 actuation assembly or brake master cylinder and pedal simulator2 brake master cylinder3 braking feel simulator device4 float or piston5 cylinder6 cavity or housing compartment7 supply hole8 outlet hole9 tank10 pressure chamber11 absorber12 pressure sensor13 absorber branch14 refilling branch15 primary branch16 braking device branch17 supply branch18 electronic control unit19 first electrically controllable shut-off valve or first valve or absorber valve20 second electrically controllable shut-off valve or second valve or refilling valve21 third electrically controllable shut-off valve or third valve or supply valve22 fourth electrically controllable shut-off valve or fourth valve or braking device valve100 braking system101 brake pedal or lever102 braking deviceX1 idle float strokeXP selected float positionX0 float rest positionPw working pressure

Claims

CLAIMS1. An actuation assembly (1) for a braking system (100) of the brake-by-wire type, said assembly (1) being configured to be connected to a brake pedal or lever (101), said assembly (1) comprising: -a brake master cylinder (2), wherein the brake master cylinder (2) comprises at least one float (4) and a cylinder (5), wherein the cylinder (5) defines a cavity or housing compartment (6) suitable for containing a working fluid, wherein the at least one float (4) is movable in the cavity (6) at least by an actuation of the brake pedal (101), wherein the cylinder (5) delimits a supply hole (7),- at least one tank (9) suitable for containing a stock of said working fluid, wherein said at least one tank (9) is fluidically connected or connectable to the cavity (6) by means of a supply branch (21) connected to the supply hole (7); wherein the cylinder (5) with the float (4) defines a pressure chamber (10) in the cavity (6), wherein the float (4) is configured to move forward in the cavity (6) over an idle float stroke (X1) obstructing the supply hole (7), fluidically isolating the pressure chamber (10) from the supply hole (7) so as to pressurize the working fluid in the pressure chamber (10),- a braking feel simulator device (3) comprising at least one absorber (11), wherein the at least one absorber (11) is fluidically connected or connectable to the pressure chamber (10) by means of an absorber branch (13) along which a first electrically controllable shut-off valve or first valve (19) is arranged, wherein the at least one absorber (12) is configured to receive the working fluid from the pressure chamber (10) applying a reaction force to the brake pedal (101) opposing the actuation of the brake pedal (101) when the first valve (19) is open, wherein said at least one tank (9) is fluidically connected or connectable to the pressure chamber (10) by means of a refilling branch (14) along which a second electrically controllable shut-off valve or second valve (20) is arranged, wherein the refilling branch (14) is configured to transfer the working fluid from the pressure chamber (10) to the at least one tank (9) when the second valve (20) is open, wherein the assembly (1) comprises:- a pressure sensor (12) configured to detect a working pressure of the pressurized working fluid in the pressure chamber (10) during the actuation of the brake pedal or lever (101),- a third electrically controllable shut-off valve or third valve (21) arranged along the supply branch (17), wherein the supply branch (17) is configured to fluidically connect the cavity (6) and / or the pressure chamber (10) to the at least one tank (9) when the third valve (21) is open and until the float (4) is moved forward over the idle float stroke (X1) by actuating the brake pedal (101), wherein the pressure sensor (12) is operatively connectable to a control and processing unit (18) to control, either by wire or electrically, an actuation of a braking device (102), wherein the first valve (19), the second valve (20), and the third valve (21) are operatively connectable to the control andprocessing unit (18) to control the opening and / or closing of the first valve (19), the second valve (20), and the third valve (21) so that when the first valve (19) is open, the second valve (20) is closed and the third valve (21) is open, once the float (4) is moved forward over the idle float stroke (X1) by actuating the brake pedal (101), the at least one absorber (12) applies a reaction force to the brake pedal (101) opposing the actuation of the brake pedal (101) and the control and processing unit (18) controls, either by wire or electrically, the actuation of the braking device (102) based on the working pressure detected by the pressure sensor (12), and so that when the first valve (19) is open, the second valve (20) is open and the third valve (21) is closed, the float (4) is positionable in a selected position (XP) in the cavity (6) by actuating the brake pedal (101) without pressurizing the working fluid in the pressure chamber (10), avoiding the control and processing unit (18) from controlling, either by wire or electrically, the actuation of the braking device (102), and so that when the first valve (19) is closed, the second valve (20) is closed and the third valve (21) is closed, the float (4) is fluidically locked in the cavity (6) in the selected position (XP) and the control and processing unit (18) controls, either by wire or electrically, the actuation of the braking device (102) based on the working pressure detected by the pressure sensor (12).

2. An actuation assembly (1) according to the preceding claim, wherein the pressure sensor (12) is positioned in the pressure chamber (10), or wherein the pressure sensor (12) is fluidically connected to the pressure chamber (10) by means of a sensor branch (23).

3. An actuation assembly (1) according to any one of the preceding claims, comprising a primary branch (15), wherein the cylinder (5) delimits an outlet hole (7), wherein the primary branch (15) is fluidically connected to the outlet hole (7), and wherein the refilling branch (14) and the absorber branch (13) are fluidically connected to the primary branch (15).

4. An actuation assembly (1) according to any one of the preceding claims, comprising a braking device branch (16), wherein the braking device branch (16) is configured to fluidically connect at least one braking device (102) to the pressure chamber (10), wherein the assembly (1) comprises a fourth electrically controllable shut-off valve or fourth valve (22) arranged along the braking device branch (16),wherein the fourth valve (22) is operatively connectable to the control and processing unit (18) to control the opening and / or closing of the fourth valve (22), so that when the fourth valve (22) is open, the first valve (19) is closed, the second valve (20) is closed and the third valve (21) is open, the braking device (102) is fluidically controllable by actuating the brake pedal (101).

5. An actuation assembly (1) according to the preceding claim, wherein the fourth valve (22) is a normally open valve, wherein the third valve (21) is a normally open valve, wherein the second valve (20) is a normally closed valve, wherein the first valve (19) is a normally closed valve, so that in case of electrical failure, the braking device (102) is fluidically controllable by actuating the brake pedal (101) in hydraulic backup mode.

6. An actuation assembly (1) according to any one of the preceding claims 1 to 3, wherein the pressure chamber (10) avoids being fluidically connected to the braking device (102), wherein the first valve (19) is a normally open valve, wherein the second valve (20) is a normally closed valve, wherein the third valve (21) is a normally open valve.

7. A braking system (100) of the brake-by-wire type for a vehicle, comprising an actuation assembly (1) according to any one of the preceding claims, connected to a brake pedal or lever (101); and at least one braking device (101) operatively connected to the actuation assembly (1),- a control and processing unit (18) operatively connected to said actuation assembly (1) and to motor means for actuating said at least one braking device (102), the control and processing unit (18) being programmed so as to actuate the braking device (102) by the motor means as a function of the actuation of the assembly (1) through the brake lever or pedal (101) in an operating by-wire condition, wherein a hydraulic connection between the actuation assembly (1) and the braking device (102) is avoided in the operating by-wire condition.

8. A method for actuating a braking system (100) of the brake-by-wire type, wherein the braking system (100) comprises an actuation assembly (1) and a braking device (101) operatively connected to the actuation assembly (1) and actuatable in an operating by-wire condition by a control and processing unit (18), wherein a hydraulic connection between the actuation assembly (1) and the braking device (102) is avoided in the operating by-wire condition,wherein the actuation assembly (1) comprises a brake master cylinder (2), at least one tank (9), a braking feel simulator device (3), and at least one pressure sensor (12), wherein the brake master cylinder (2) comprises at least one float (4) and a cylinder (5), wherein the cylinder (5) defines a cavity or housing compartment (6) suitable for containing a working fluid, wherein the at least one float (4) is movable in the cavity (6) at least by actuating the brake pedal (101), wherein the cylinder (5) delimits a supply hole (7), wherein the at least one tank (9) is configured to contain a stock of said working fluid, wherein said at least one tank (9) is fluidically connected or connectable to the cavity (6) by means of a supply branch (21) connected to the supply hole (7); wherein the cylinder (5) with the float (4) defines a pressure chamber (10) in the cavity (6), wherein the float (4) is configured to move forward in the cavity (6) over an idle float stroke (X1) obstructing the supply hole (7), fluidically isolating the pressure chamber (10) from the supply hole (7) so as to pressurize the working fluid in the pressure chamber (10), wherein the braking feel simulator device (3) comprises at least one absorber (11), wherein the at least one absorber (11) is fluidically connected or connectable to the pressure chamber (10) by means of an absorber branch (13), wherein the pressure sensor (12) is configured to detect a working pressure of the pressurized working fluid in the pressure chamber (10) during the actuation of the brake pedal or lever (101), wherein the braking system (100) is actuatable, in the operating by-wire condition, at least according to a first actuation mode and according to a second actuation mode, wherein the method includes a step of selecting the actuation mode, wherein one of the first actuation mode and the second actuation mode is selected, for example by means of a mode selector, wherein by selecting the first actuation mode, upon actuation of the brake pedal (101), the float (4) moves forward from a float rest position (X0) at least over the idle float stroke (X1) and the at least one absorber (12) receives the working fluid from the pressure chamber (10), applying a reaction force to the brake pedal (101) opposing the actuation of the brake pedal (101), and the pressure sensor (12) detects the working pressure (Pw) of the working fluid in the pressure chamber (10) and the braking device (102) is actuated by wire based on the detected working pressure (Pw), wherein by selecting the second actuation mode there is included- - a positioning step, wherein the float (4) is positionable in a selected position (XP) in response to the actuation of the brake pedal (101), wherein the selected position (XP) is selected from the rest position (X0) and any forward position in the cavity (6), avoiding actuating by wire the braking device (102) based on the working pressure (Pw) detected during the positioning step,- a step of locking the selected position of the float (4), wherein the float (4) is hydraulicallylocked in the selected position (XP), wherein, once the float (4) has been hydraulically locked in the selected position (XP), upon actuation of the brake pedal (101) the working fluid in the pressure chamber (10) applies a reaction force to the brake pedal (101) opposing the actuation of the brake pedal (101), and the pressure sensor (12) detects the working pressure (Pw) of the working fluid in the pressure chamber (10) and the braking device (102) is actuated by wire based on the detected working pressure (Pw).

9. An actuation method according to the preceding claim, wherein in the positioning step, the float (4) is positionable in the selected position in response to the actuation of the brake pedal (101), avoiding pressurizing the working fluid in the pressure chamber (10), and / or wherein the step of selecting the actuation mode, in the absence of a selection by the user, includes automatically selecting the first actuation mode.

10. An actuation method according to claim 8 or 9, wherein the actuation assembly (1) is an actuation assembly according to any one of claims 1 to 7, and / or wherein the actuation assembly (1) comprises a first electrically controllable shut-off valve or first valve (19) arranged along the absorber branch (13), wherein said at least one tank (9) is fluidically connected or connectable to the pressure chamber (10) by means of a refilling branch (14) along which a second electrically controllable shut-off valve or second valve (20) is arranged, wherein the actuation assembly (1) comprises a third electrically controllable shut-off valve or third valve (21) arranged along the supply branch (17), wherein by selecting the first actuation mode, the first valve (19), the second valve (20) and the third valve (21) are controlled so that the first valve (19) is open, the second valve (20) is closed and the third valve (21) is open so that upon actuation of the brake pedal (101), once the float (4) has been moved forward over the idle float stroke (X1) by actuating the brake pedal (101), the at least one absorber (12) applies a reaction force to the brake pedal (101) opposing the actuation of the brake pedal (101) and the control and processing unit (18) controls, either by wire or electrically, the actuation of the braking device (102) based on the working pressure detected by the pressure sensor (12); wherein by selecting the second actuation mode, during the positioning step, the first valve (19), the second valve (20), and the third valve (21) are controlled so that the first valve (19) is open, thesecond valve (20) is open and the third valve (21) is closed, so that the float (4) is positionable in a selected position (XP) in the cavity (6) by actuating the brake pedal (101) without pressurizing the working fluid in the pressure chamber (10) avoiding the control and processing unit (18) from controlling, either by wire or electrically, the actuation of the braking device (102); and during the locking step, the first valve (19), the second valve (20), and the third valve (21) are controlled so that the first valve (19) is closed, the second valve (20) is closed and the third valve (21) is closed, so that the float (4) is fluidically locked in the cavity (6) in the selected position (XP) and the control and processing control unit (18) controls, either by wire or electrically, the actuation of the braking device (102) based on the working pressure detected by the pressure sensor (12).

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