Braking system

Abstract

A braking system (1) of the Brake-By-Wire type, comprising a braking assembly (2); an electro-hydraulic actuation device (3) connected to the braking assembly (2) by means of a first hydraulic pipe (4), wherein the electro-hydraulic actuation device (3) comprises a positive displacement pump (5) comprising a cylinder (6), a piston (7), an electromechanical actuator (9), wherein the piston (7) comprises a piston head (10) connected to a piston rod (11), wherein the piston head (10) defines, inside the cylinder (6), a reaction chamber (12) and an opposite action chamber (13), wherein the piston rod (11) extends into the action chamber (13), and wherein the reaction chamber (12) is fluidly connected to the braking assembly (2) by means of the first hydraulic pipe (4), wherein said braking system (1) further comprises a hydraulic actuation device (14) configured to actuate the braking assembly (2), preferably in an emergency or failure condition of the electro-hydraulic actuation device (3), wherein the hydraulic actuation device (14) is connected to the cylinder (6) by means of a second hydraulic pipe (15), and wherein the piston (7) comprises an additional piston rod (16), connected to the piston head (10) and extending into the reaction chamber (12).

Description

"Braking system" DESCRIPTION

[0001] Field of the invention

[0002] The present invention relates to a braking system of the Brake-By-Wire ("BBW') type of a vehicle with two or more wheels actuatable by a driver by means of a brake pedal or lever.

[0003] Background art

[0004] In braking systems of the BBW type, there is a decoupling between force and displacement applied to the brake pedal or lever by the driver and the resulting braking force which is applied by the calipers to the vehicle wheels. In particular, the force and displacement imparted by the driver on the brake pedal or lever are transduced into an electrical signal which is processed by a control unit to control the actuation of the braking system calipers.

[0005] For safety reasons, the BBW-type braking systems are equipped with actuation devices, e.g., hydraulic or mechanical or electromechanical, manual or emergency actuation devices, which intervene in case of failure or malfunction of the electrical and electronic devices and means of the main BBW system.

[0006] A braking system of the BBW type generally comprises at least one braking assembly acting on a wheel of the vehicle, actuatable by at least one hydraulic or electro- hydraulic actuation device, a system for generating pressure in the braking system connected to and actuatable by the brake pedal, and a control unit which, by means of a safety manifold, directs the pressurized braking fluid and controls the actuation of at least one hydraulic or electro-hydraulic actuation device.

[0007] The electro-hydraulic actuation device is generally a positive displacement pump, comprising a cylinder-piston assembly, in which the piston is movable by electromechanical means.

[0008] A braking system of this type can operate in two modes:

[0009] - normal or by-wire braking mode: the driver, by means of the brake pedal, generates the pressure which reaches the safety manifold. Such a pressure is not directed to the braking assembly, but can be directed, for example, to a braking feel simulator device. Once the braking request has been detected, the control unit commands the electro-hydraulic actuation device to generate a braking force according to the driver's request.

[0010] - Manual or emergency braking mode: the driver, by means of the brake pedal, generates the pressure which reaches the safety manifold. Such a pressure, by meansof the control unit, is directly connected to the hydraulic actuation device, and thus to the braking assembly, so as to generate a braking force according to the driver's request.

[0011] Hence, the braking system can switch between the two braking modes according to the detection, by the control unit, of normal operating conditions or braking system failure.

[0012] A disadvantage of a BBW braking system thus described is that, in manual braking conditions, typically when the power supply is interrupted, there is less braking efficiency of the system, because some of the work or energy expended by the driver to actuate the hydraulic actuation device (acting on the brake pedal or lever connected to the cylinder-piston assembly) is undesirably expended to move the reversible positive displacement pump, i.e., the piston of the cylinder of the electro-hydraulic actuation device, backwards, and is thus not expended totally to actuate the braking assembly.

[0013] Such a backward movement is due to the fact that the piston motion is reversible even when the electro-hydraulic actuation device is not powered (i.e., in case of failure).

[0014] Braking systems are known, comprising blocking mechanisms configured to block such a piston retraction. Such blocking mechanisms can comprise a piston with a grooved profile and a pin adapted to geometrically engage such a profile so as to block the movement thereof, or a piston with a shaped profile and a pin adapted to slide over the shaped profile and implement a frictional force such as to block the movement thereof.

[0015] However, such known blocking mechanisms increase the complexity of the braking system as well as production and maintenance costs, in addition to causing undesired noises and force exchanges.

[0016] Solution

[0017] It is the object of the present invention to provide an improved braking system adapted to solve at least some of the drawbacks of the prior art.

[0018] It is a particular object of the present invention to provide a braking system having increased efficiency, in which the losses of work or energy expended by the driver to actuate the braking assembly under emergency conditions are reduced or eliminated.

[0019] It is a further particular object of the present invention to provide a braking system which achieves such an increased efficiency while exhibiting reduced complexity and cost of production and maintenance compared to the prior art.

[0020] These and other objects are achieved by a braking system according to claim

[0021] The dependent claims relate to preferred and advantageous embodiments of the present invention.

[0022] Figures

[0023] In order to better understand the invention and appreciate the advantages thereof, some non-limiting exemplary embodiments thereof will be described below with reference to the accompanying drawings, in which:

[0024] - figure 1 is a diagrammatic depiction of a braking system operating a braking in a normal or by-wire mode, in which a thicker hatching indicates the pressurized braking fluid transport lines, according to an embodiment of the invention;

[0025] - figure 2 is a diagrammatic depiction of a braking system operating a braking in a manual or emergency mode, in which a thicker hatching indicates the pressurized braking fluid transport lines, according to an embodiment of the invention;

[0026] - figure 3 is a diagrammatic depiction of a positive displacement pump of an electro-hydraulic actuation device of a braking system, according to an embodiment of the invention;

[0027] - figure 4 is a perspective view of an actuation system of a braking system, according to an embodiment of the invention;

[0028] - figure 5 is a further perspective view of the actuation system in figure 4 in a partially disassembled configuration;

[0029] - figure 6 is a top view of the actuation system in figure 4, in longitudinal section;

[0030] - figure 7 is a side view of the actuation system in figure 4, in axial section;

[0031] - figure 8 is an enlarged view of a portion of the actuation system in figure 7;

[0032] - figure 9 is a perspective view of the actuation system in figure 4, in a partially disassembled configuration;

[0033] - figure 10 is a further perspective view of the actuation system in figure 4, in a partially disassembled configuration;

[0034] - figure 11 is a perspective view of the actuation system in figure 4, in a partially disassembled configuration.

[0035] Description of some preferred embodiments

[0036] The present invention is adapted to be applied to a braking system of the Brake-By-Wire ("BBW") type of vehicles with two or more wheels, actuatable by a driver by means of a brake pedal or lever. Therefore, in the present description, the term "brake pedal" means indistinctly both a brake pedal for motor vehicles and the like and a brakelever for motorcycles, mopeds, and the like, unless otherwise specified.

[0037] Braking system 1

[0038] With reference to the figures, a braking system is generally indicated by reference numeral 1. The braking system 1 is of the Brake-By-Wire (BBW) type.

[0039] The braking system 1 comprises at least one braking assembly 2.

[0040] The braking assembly 2 is configured to apply a braking force to a wheel or axle of a vehicle on which the braking system 1 is installed.

[0041] By way of example, the braking assembly 2 can comprise a disc brake which comprises a brake caliper associated with a brake disc connected to a vehicle wheel.

[0042] The braking system 1 further comprises an electro-hydraulic actuation device 3. The electro-hydraulic actuation device 3 is configured to actuate the braking assembly 2.

[0043] The electro-hydraulic actuation device 3 is connected to the braking assembly 2, in particular fluidly connected, by means of a first hydraulic pipe 4.

[0044] The electro-hydraulic actuation device 3 comprises a positive displacement pump 5.

[0045] The positive displacement pump 5 comprises a cylinder 6 and a piston 7.

[0046] The piston 7 extends along an actuation axis 8 and is slidingly housed inside the cylinder 6.

[0047] The positive displacement pump 5 further comprises an electromechanical actuator 9. The electromechanical actuator 9 is connected to the piston 7 and is configured to move the piston 7 along the actuation axis 8.

[0048] The piston 7 comprises a piston head 10 connected to a piston rod 11.

[0049] The piston head 10 defines, inside the cylinder 6, a reaction chamber 12 and an opposite action chamber 13.

[0050] Therefore, the reaction chamber 12 and the action chamber 13 are mutually separated by the piston head 10.

[0051] The piston rod 11 extends into the action chamber 13.

[0052] In particular, the piston rod 11 is connected to the electromechanical actuator 9. The electromechanical actuator 9 can thus actuate the piston 7 along the cylinder 6.

[0053] The reaction chamber 12 is fluidly connected to the braking assembly 2 by means of the first hydraulic pipe 4.

[0054] The actuation of the piston head 10 along the actuation axis 8 towards the reaction chamber 12 and also such as to transport the braking fluid towards the firsthydraulic pipe 4 and then towards the braking assembly 2, pressurizes the braking fluid at the braking assembly 2, which urges the braking assembly 2 to apply a braking force.

[0055] The braking system 1 further comprises a hydraulic actuation device 14.

[0056] The hydraulic actuation device 14 is configured to actuate the braking assembly 2, preferably in a condition of emergency or failure of the electro-hydraulic actuation device 3, and in particular of the electromechanical actuator 9.

[0057] The hydraulic actuation device 14 is connected to the cylinder 6, in particular fluidly connected, by means of a second hydraulic pipe 15.

[0058] The second hydraulic pipe 15 is distinct from the first hydraulic pipe 4.

[0059] Furthermore, the piston 7 comprises an additional piston rod 16.

[0060] The additional piston rod 16 is connected to the piston head 10.

[0061] Furthermore, the additional piston rod 16 extends into the reaction chamber 12.

[0062] As a result, the additional piston rod 16 is positioned opposite to the piston rod 11 , with respect to the piston head 10.

[0063] Advantageously, a braking system 1 thus configured exhibits higher braking efficiency than the prior art because it minimizes or cancels the loss of work expended by the driver to actuate the hydraulic actuation device 14.

[0064] Indeed, the presence of an additional piston rod 16 opposite to the piston rod 11 with respect to the piston head 10 causes a reaction surface 18 of the piston head 10 facing the reaction chamber 12 to substantially correspond to an action surface 17 of the piston head 10 facing the action chamber 13.

[0065] Therefore, when the hydraulic actuation device 14 is actuated and the braking fluid in the cylinder 6 is pressurized and transported towards the braking assembly 2, the resultant force acting on the action surface 17 is substantially equal and opposite to the resultant force acting on the reaction surface 18, because the pressure of the braking fluid is substantially the same in the action 13 and reaction 12 chambers.

[0066] Therefore, upon the actuation of the braking assembly 2 by means of the hydraulic actuation device 14, the overall resultant force acting on the piston 7, and in particular on the piston head 10, is substantially zero, and therefore the piston 7 is not moved backward as is the case of the known solutions, but remains substantially stationary. As a result, the work expended by the driver to actuate the braking assembly 2 by means of the hydraulic actuation device 14 is entirely used to actuate the braking assembly 2.

[0067] With further advantage, a braking system 1 thus configured does not require blocking mechanisms which act in engagement on the piston rod or special piston rod geometries adapted to achieve such an engagement or interference blocking. As a result, the braking system 1 thus configured is less complex and less expensive than the known systems.

[0068] Piston 7

[0069] The piston head 10 comprises an action pressure surface 17, facing the action chamber 13.

[0070] Under failure or emergency braking conditions, upon the actuation of the hydraulic actuation device 14, the pressurized brake fluid acts on the action pressure surface 17 to actuate the movement of the piston 7 and activate the braking assembly 2. Therefore, the force applied by the braking fluid to the piston head 10, on the side of the action chamber 13, is substantially equal to the pressure of the braking fluid in the cylinder 6, and in particular in the action chamber 13, multiplied by the area of the action pressure surface 17. The area of the action pressure surface 17 corresponds to the area of the piston head 10 from which the area of the piston rod 11 is subtracted.

[0071] Under normal, or "by-wire," braking conditions, the braking assembly 2 is instead actuated by means of the electro- hydraulic device 3, in particular by means of the electromechanical actuator 9, as will be described below. In particular, the electromechanical actuator 9 moves the piston 7 along the actuation axis 8 so as to pressurize the braking fluid inside the reaction chamber 12, thus actuating the braking assembly 2. Hence, in this case, no pressurization is generated in the action chamber 13.

[0072] In the present description, "area" means the area measured in cross-section with respect to the actuation axis 8.

[0073] The piston head 10 comprises a reaction pressure surface 18, facing the reaction chamber 12.

[0074] The pressurized brake fluid acts on the reaction pressure surface 18 during the actuation of the piston 7 and the activation of the braking assembly 2, in particular in reaction to the actuation of the piston 7. As a result, the reaction force applied by the braking fluid to the piston head 10, on the side of the reaction chamber 12, is substantially equal to the pressure of the braking fluid in the cylinder 6, and in particular in the action chamber 12, multiplied by the area of the reaction pressure surface 18. The area of the reaction pressure surface 18 corresponds to the area of the piston head 10 from which the area of the additional piston rod 16 is subtracted.

[0075] According to an embodiment, the ratio of the area of the action pressure surface 17 to the area of the reaction pressure surface 18 is between 0.90:1.00 and 1.00:0.90.

[0076] According to an embodiment, the ratio of the area of the action pressure surface 17 to the area of the reaction pressure surface 18 is between 0.95:1.00 and 1.00:0.95.

[0077] According to an embodiment, the area of the action pressure surface 17 is substantially equal to the area of the reaction pressure surface 18.

[0078] Advantageously, in a system 1 thus configured, during actuation of the hydraulic actuation device 14, the piston 7 undergoes an overall resultant force equal to zero, thus remaining stationary and not dissipating useful work to actuate the braking assembly 2. Therefore, even if, in the case of a failure, the piston 7 were in an intermediate position between the stroke start and the stroke end in the cylinder 6, the piston 7 would remain stationary upon the activation and actuation of the hydraulic actuation device 14.

[0079] According to an embodiment, the piston rod 11 and the additional piston rod 16 are connected to the same piston head 10.

[0080] According to an embodiment, the piston head 10 is substantially cylindrical in shape.

[0081] According to an embodiment, the piston rod 11 is substantially cylindrical in shape. According to an embodiment, the additional piston rod 16 is substantially cylindrical in shape.

[0082] According to an embodiment, the diameter of the piston rod 11 is substantially equal to the diameter of the additional piston rod 16. The diameter is measured in the direction transverse to the actuation axis 8.

[0083] According to an embodiment, the piston head 10 comprises an annular seal 42 extending circularly about the piston head 10.

[0084] The annular seal 42 is interposed between the piston head 10 and the cylinder 6.

[0085] According to an embodiment, the annular seal 42 is housed in an annular seat formed circumferentially in the piston head 10.

[0086] According to an embodiment, the annular seal 42 is a lip seal.

[0087] According to an embodiment, the annular seal 42, and in particular the lip seal, is configured to prevent a flow of braking fluid from the reaction chamber 12 to the actionchamber 13, in particular during the actuation of the electro-hydraulic actuation device 3. Furthermore, the annular seal 42, and in particular the lip seal, is configured to allow a flow of braking fluid from the action chamber 13 to the reaction chamber 12, in particular during the actuation of the hydraulic actuation device 14.

[0088] A malfunction, or otherwise a reduction in the operating efficiency of the electro-hydraulic drive device 3 is thus avoided, but the operation of the hydraulic actuation device 14 is ensured.

[0089] Cylinder 6

[0090] According to an embodiment, the hydraulic actuation device 14 is fluidly connected to the action chamber 13 by means of the second hydraulic pipe 15.

[0091] Specifically, the second hydraulic pipe 15 leads into the action chamber 13.

[0092] According to an embodiment, the cylinder 6 forms the second hydraulic pipe 15. Therefore, the second hydraulic pipe 15 is formed in one piece with the cylinder 6.

[0093] According to an embodiment, the second hydraulic pipe 15 extends passing through the cylinder 6, in the transverse direction with respect to the actuation axis 8.

[0094] According to an embodiment, the second hydraulic pipe 15 comprises an inlet portion 19 and an orifice 20.

[0095] The inlet portion 19 has a larger fluid passage section than the orifice 20.

[0096] The inlet portion 19 and the action chamber 13 are fluidly connected to each other by means of the orifice 20.

[0097] Therefore, the orifice 20 leads into the inlet portion 19. Furthermore, the orifice 20 leads into the action chamber 13.

[0098] According to an embodiment, the inlet portion 19 extends projecting from the cylinder 6, preferably in the radial direction with respect to the actuation axis 8.

[0099] The first hydraulic pipe 4 leads into the reaction chamber 12 of the cylinder 6.

[0100] According to an embodiment, the cylinder 6 forms the first hydraulic pipe 4. As a result, the first hydraulic pipe 4 is formed in one piece with the cylinder 6.

[0101] According to an embodiment, the first hydraulic pipe 4 extends passing through the cylinder 6, in the transverse direction with respect to the actuation axis 8.

[0102] According to an embodiment, the first hydraulic pipe 4 comprises an inlet portion 19 and an orifice 20.

[0103] The inlet portion 19 has a larger fluid passage section than the orifice 20.

[0104] The inlet portion 19 and the reaction chamber 12 are fluidly connected to each other by means of the orifice 20.

[0105] Therefore, the orifice 20 leads into the inlet portion 19 and into the reaction chamber 12.

[0106] According to an embodiment, the inlet portion 19 extends projecting from the cylinder 6, preferably in the radial direction with respect to the actuation axis 8.

[0107] According to an embodiment, the inlet portion 19 of the first hydraulic pipe 4 and the inlet portion of the second hydraulic pipe 15 are positioned along the same axis parallel to the actuation axis 8.

[0108] According to an embodiment, the orifice 20 of the first hydraulic pipe 4 and the orifice 20 of the second hydraulic pipe 15 are positioned along the same axis parallel to the actuation axis 8.

[0109] According to an embodiment, the cylinder 6 extends between a first connection surface 21 and an opposite second cylinder end 22.

[0110] According to an embodiment, the first cylinder end 21 corresponds to a stroke end position of the piston 7, and the second cylinder end 22 corresponds to a stroke start position of the piston 7.

[0111] Specifically, in the stroke start position, the piston rod 11 is positioned at, either facing or abutting against, the second cylinder end 22.

[0112] In the stroke end position, the additional piston rod 16 is positioned at, either facing or abutting against, the first cylinder end 21 .

[0113] According to an embodiment, the braking system 1 comprises a cap 23. The cap 23 is fixed to the cylinder 6 at the first cylinder end 21 , so as to close the cylinder 6.

[0114] Therefore, in the stroke end position, the additional piston rod 16 is positioned facing or abutting against the cap 23.

[0115] Electromechanical actuator 9

[0116] According to an embodiment, the braking system 1 comprises a housing structure 24. The housing structure 24 is connected to the cylinder 6.

[0117] The electromechanical actuator 9 is housed inside the housing structure 24.

[0118] According to an embodiment, the housing structure 24 is connected to the cylinder 6 at the second cylinder end 22.

[0119] According to an embodiment, the electromechanical actuator 9 comprises a screw-nut screw system 25 comprising a screw 26 and a nut screw 27.

[0120] The nut screw 27 is externally screwed to the screw 26. A rotation of the nut screw 27 about the actuation axis 8 corresponds to a translation of the screw 26 along the actuation axis 8.

[0121] According to an embodiment, the electromechanical actuator 9 comprises an electric motor 28.

[0122] The electric motor 28 is mechanically connected to the nut screw 27 so as to transfer mechanical power to the nut screw 27.

[0123] According to an embodiment, the screw-nut screw system 25 is positioned coaxially to the actuation axis 8.

[0124] According to this embodiment, the screw-nut screw system 25 is positioned coaxial to the piston 7.

[0125] According to an embodiment, the screw 26 is connected to a piston rod 11. Specifically, the screw 26 is fixed to the piston rod 11 opposite to the piston head 10.

[0126] According to this embodiment, a rotation of the nut screw 27 about the actuation axis 8 corresponds to a translation of the screw 26 and the piston 7 along the actuation axis 8. Under by-wire braking conditions, the braking fluid inside the cylinder 6, and in particular inside the reaction chamber 12, is thus pressurized and transported by the positive displacement pump 5 towards the braking assembly 2.

[0127] Valve 36

[0128] According to an embodiment, the braking system 1 comprises a valve 36.

[0129] Preferably, the valve 36 is a by-pass valve.

[0130] The valve 36 is positioned inside the cylinder 6.

[0131] The valve 36 is configured to allow a flow of braking fluid from the second hydraulic pipe 15 towards the first hydraulic pipe 4 during the actuation of the hydraulic actuation device 14.

[0132] According to an embodiment, the valve 36 is configured to allow a flow of braking fluid from the second hydraulic pipe 15 towards the first hydraulic pipe 4 during the actuation of the hydraulic actuation device 14, and prevent a flow of braking fluid from the first hydraulic pipe 4 towards the second hydraulic pipe 15. In particular, the valve 36 is configured to prevent a flow of braking fluid from the first hydraulic pipe 4 towards the second hydraulic pipe 15, when the piston 7 is not positioned in a stroke start position.

[0133] Specifically, the valve 36 is configured to allow a flow of braking fluid transported into the cylinder 6 and coming from the second hydraulic pipe 15 towards the first hydraulic pipe 4 in the direction of the braking assembly 2, during the actuation of the hydraulic actuation device 14. According to a preferred embodiment, the valve 36 is configured to allow a flow of braking fluid from the action chamber 13 to the reaction chamber 12 during the actuation of the hydraulic actuation device 14.

[0134] According to an embodiment, the braking system 1 is configured so that the positioning of the piston 7 in its stroke start position corresponds to an opening of the valve 36. Therefore, the valve 36 is configured to be open when the piston 7 is in the stroke start position, i.e., the valve 36 allows a flow of braking fluid from the reaction chamber 12 to the action chamber 13.

[0135] Preferably, the valve 36 is further configured to allow a flow of overpressurized braking fluid from the reaction chamber 12 towards the action chamber 13 when the piston 7 is in the stroke start position.

[0136] "Over-pressurized" means that the fluid is undesirably pressurized, for example due to an undesired increase in temperature, which could cause undesired effects such as residual torque phenomena in the braking assembly 2, for example.

[0137] Advantageously, in addition to allowing the actuation of the braking assembly 2 by means of the hydraulic actuation device 14 under manual braking conditions, the valve 36 is configured, when the piston 7 is in the stroke start position, to relieve possible overpressure generatable in the braking fluid in the reaction chamber 12, directly connected to the braking assembly 2, e.g., due to an increase in temperature and which could cause residual torque phenomena in the braking assembly 2.

[0138] According to an embodiment, the valve 36 is positioned at the piston head 10.

[0139] According to an embodiment, the valve 36 is integrated inside the piston head 10.

[0140] According to an embodiment, the piston head 10 forms an extended passage pipe 37 passing through the piston head 10.

[0141] The passage pipe 37 fluidly connects the action chamber 13 to the reaction chamber 12.

[0142] The valve 36 comprises an adjustment member 38 positioned at the passage pipe 37.

[0143] The adjustment member 38 is configured to open or close the passage pipe 37, so as to prevent or allow a flow of braking fluid through the passage pipe 37.

[0144] According to an embodiment, the adjustment member 38 is positioned coaxially to the actuation axis 8.

[0145] According to an embodiment, the adjustment member 38 is elastically biased to close the passage pipe 37 through elastic means 39 interposed between the adjustment member 38 and the additional piston rod 16.

[0146] Upon an actuation of the hydraulic actuation device 14, the pressurized brakefluid is such as to open and flow through the passage pipe 37, urging the adjustment member 38 to the opening configuration

[0147] The braking fluid pressurized by the hydraulic actuation device 14 can thus reach the braking assembly 2 substantially without any type of restriction or occlusion, and the necessary flow of braking fluid towards the braking assembly 2 is thus ensured. Indeed, the mere passage of the braking fluid from the action chamber 13 towards the reaction chamber 12 through the annular seal 42 of the piston head 10 would not be immediately sufficient, and would require more urging and pressurization by the driver.

[0148] Furthermore, the valve 36 thus configured is such as to be opened by the hydraulic actuation device 14 in any position the piston 7 should be in if the electro- hydraulic actuation device 3 fails.

[0149] According to an embodiment, the braking system 1 comprises an abutment pin 40.

[0150] The abutment pin 40 is configured to act as an abutment for the adjustment member 38 of the valve 36.

[0151] The abutment pin 40 is positioned opposite to the elastic means 39, with respect to the adjustment member 38.

[0152] According to an embodiment, the abutment pin 40 is positioned in the action chamber 13, facing the piston head 10, preferably transversely to the actuation axis 8.

[0153] According to an embodiment, the abutment pin 40 is placed inside a longitudinal through groove 41 formed in the piston rod 11.

[0154] The longitudinal through groove 41 extends along the actuation axis 8.

[0155] By means of the longitudinal through groove 41 , a translation of the piston 7 along the actuation axis 8 is allowed as well as the simultaneous positioning and securing of the abutment pin 41 with respect to the cylinder 6.

[0156] According to an embodiment, the abutment pin 40 is positioned at the inlet portion 19 of the second hydraulic pipe 15, parallel to the orifice 20, and extends passing through the action chamber 13.

[0157] According to an embodiment, the abutment pin 40 is positioned at the stroke start position of the piston 7. When the piston 7 is in the stroke start position, the adjustment member 38 thus abuts against the pin 40, thus opening the valve 36 and in particular the passage pipe 37. Advantageously, in the stroke start position, the opening of the valve 36 thus allows relieving any overpressure in the braking fluid. Conversely, when the piston 7 moves away from the stroke start position, the adjustment member 38detaches from the pin 40, closing the passage pipe 37. The closing of the passage pipe 37 can be caused, for example, by the elastic means 39 acting on the adjustment member 38 to close the passage pipe 37 as well as by the pressurization of the braking fluid inside the reaction chamber 12.

[0158] Hydraulic actuation device 14

[0159] According to an embodiment, the hydraulic actuation device 14 comprises a hydraulic cylinder 29 and a hydraulic piston 30 movable inside the hydraulic cylinder 29, so as to form a delivery chamber 32 in the hydraulic cylinder 29.

[0160] The delivery chamber 32 is fluidly connected to the positive displacement pump 5, and in particular to the cylinder 6 of the electro-hydraulic actuation device 3, by means of the second hydraulic pipe 15.

[0161] The hydraulic actuation device 14 further comprises a brake pedal 31, actuatable by a driver.

[0162] The brake pedal 31 is connected to hydraulic piston 30.

[0163] An actuation of the brake pedal 31 by a driver corresponds to an actuation of the hydraulic piston 30 inside the hydraulic cylinder 29. The actuation of the hydraulic piston 30 pressurizes and transports the hydraulic fluid through the second hydraulic pipe 15, towards the braking assembly 2. Thereby, in particular under conditions of emergency or failure of the electro-hydraulic actuation device, the driver can actuate the braking assembly 2 by means of the brake pedal 31 hydraulically connectable to the braking assembly 2 by means of the hydraulic actuation device 14.

[0164] According to an embodiment, the braking system 1 comprises flow control means 33.

[0165] The flow control means 33 are configured to manage and control the transport of braking fluid inside the braking system 1.

[0166] According to an embodiment, the control means 33 comprise a control unit 34 and a plurality of sensors.

[0167] The plurality of sensors is adapted to detect the operation of the braking system 1. In particular, the plurality of sensors is configured to detect any malfunction or failure of the electro-hydraulic actuation device 3, and in particular of the electromechanical actuator 9.

[0168] The control unit 34 is configured to receive and process the detections performed by the plurality of sensors.

[0169] Advantageously, the control unit 34 is configured to allow an actuation of thehydraulic actuation device 14 and is configured to command the transport of braking fluid at the second hydraulic pipe 15 upon the detection of a malfunction or failure of the electro-hydraulic actuation device 3.

[0170] According to an embodiment, the flow control means 33 comprise a manifold 35 configured to transport the hydraulic fluid.

[0171] In particular, the manifold 35 is configured to prevent a transport of hydraulic fluid through the second hydraulic pipe 15 when electro-hydraulic actuation device 3 is in normal operation. Conversely, upon detection of a malfunction or failure of the electro- hydraulic actuation device 3, the manifold 35 is configured to transport the hydraulic fluid through the second hydraulic pipe 15, thus allowing an actuation of the hydraulic actuation device 14.

[0172] According to an embodiment, the flow control means 33 comprise a braking feel simulator device. The braking feel simulator device is fluidly connected to the manifold 35.

[0173] Preferably, under normal operating conditions of the electro-hydraulic actuation device 3, the control unit 34 is configured to command the transport, by means of the manifold 35, of the braking fluid pressurized by the brake pedal 31 towards the braking feel simulator device.

[0174] According to an embodiment, the braking system 1 comprises a plurality of braking assemblies 2 as previously described. The plurality of braking assemblies 2 is configured to apply a braking force to respective wheels or axles of a vehicle.

[0175] Furthermore, the braking system 1 comprises a plurality of electro-hydraulic actuation devices 3 as previously described. The plurality of electro-hydraulic actuation devices 3 is connected to the plurality of braking assemblies 2, respectively, by means of respective first hydraulic pipes 4, and is configured to actuate the plurality of braking assemblies 2.

[0176] Furthermore, the hydraulic actuation device 14 comprises a hydraulic cylinder 29 and a hydraulic piston 30 movable in the hydraulic cylinder 29, so as to form a delivery chamber 32 in the hydraulic cylinder 29. The delivery chamber 32 is fluidly connected to the respective positive displacement pumps 5, preferably to the respective cylinders 6, of the plurality of electro-hydraulic actuation devices 3, by means of a respective second hydraulic pipe 15. The hydraulic actuation device 14 comprises a brake pedal 31 , actuatable by a driver. The brake pedal 31 is connected to the hydraulic piston 30, and an actuation of the brake pedal 31 by a driver corresponds to an actuation of the hydraulic piston 30 inside the hydraulic cylinder 29.

[0177] The braking system 1 further comprises at least one control unit 34 and a plurality of sensors adapted to detect the operation of the braking system 1 and a possible malfunction or failure of the electro-hydraulic actuation device 3, in particular of the electromechanical actuator 9. According to an embodiment, the braking system 1 comprises only one control unit 34. According to an embodiment, the braking system 1 comprises two control units 34.

[0178] The at least one control unit 34 is configured to receive and process the detections performed by the plurality of sensors. The at least one control unit 34 is configured to allow an actuation of the hydraulic actuation device 14 and command the transport of braking fluid at a respective second hydraulic pipe 15 upon the detection of a malfunction or failure of the electro-hydraulic actuation device 3.

[0179] The braking system 1 further comprises a single manifold 35. The manifold 35 is configured to transport the hydraulic fluid to the plurality of electro-hydraulic actuation devices 3 and to the plurality of braking assemblies 2.

[0180] The at least one control unit 34 is configured to prevent, by means of the single manifold 35, the transport of hydraulic fluid through the second hydraulic pipes 15 when the electro- hydraulic actuation devices 3 are in normal operation. Furthermore, the control unit 34 is configured to transport, by means of the single manifold 35, the hydraulic fluid through the second hydraulic pipes 15 upon detection of a malfunction or failure of the plurality of electro-hydraulic actuation devices 3.

[0181] Advantageously, a braking system 1 thus configured allows controlling and transporting the hydraulic fluid into all braking assemblies 2 and electro-hydraulic actuation devices 3 by means of a single manifold 35 controlled by one or more control units 34.

[0182] Obviously, those skilled in the art will be able to make changes or adaptations to the present invention, without however departing from the scope of the following claims.List of reference numerals1. Braking system2. Braking assembly3. Electro-hydraulic actuation device4. First hydraulic pipe5. Positive displacement pump6. Cylinder7. Piston8. Actuation axis9. Electromechanical actuator10. Piston head11. Piston rod12. Reaction chamber13. Action chamber14. Hydraulic actuation device15. Second hydraulic pipe16. Additional piston rod17. Action surface18. Reaction surface19. Inlet portion20. Orifice21. First cylinder end22. Second cylinder end23. Cap24. Housing structure25. Screw-nut screw system26. Screw27. Nut screw28. Electric motor29. Hydraulic cylinder30. Hydraulic piston31. Brake pedal32. Delivery chamber33. Flow control means34. Control unit

Claims

Claims1. A braking system (1) of the Brake-By-Wire type, comprising:- at least one braking assembly (2), configured to apply a braking force to a wheel or axle of a vehicle;- an electro-hydraulic actuation device (3), configured to actuate the braking assembly (2), and connected to the braking assembly (2) by means of a first hydraulic pipe (4), wherein the electro- hydraulic actuation device (3) comprises a positive displacement pump (5) comprising: a cylinder (6); a piston (7), extending along an actuation axis (8), and slidingly housed inside the cylinder (6); an electromechanical actuator (9), connected to the piston (7) and configured to move the piston (7) along the actuation axis (8), wherein the piston (7) comprises a piston head (10) connected to a piston rod(11), wherein the piston head (10) defines, inside the cylinder (6), a reaction chamber(12) and an opposite action chamber (13), wherein the piston rod (11) extends into the action chamber (13), and wherein the reaction chamber (12) is fluidly connected to the braking assembly (2) by means of the first hydraulic pipe (4), said braking system (1) further comprising a hydraulic actuation device (14), configured to actuate the braking assembly (2), preferably in an emergency or failure condition of the electro-hydraulic actuation device (3), wherein the hydraulic actuation device (14) is connected to the cylinder (6) by means of a second hydraulic pipe (15), and wherein the piston (7) comprises an additional piston rod (16), connected to the piston head (10) and extending into the reaction chamber (12).

2. A braking system (1) according to claim 1 , wherein the piston rod (11) and additional piston rod (16) are connected to the same piston head (10).

3. A braking system (1) according to any one of the preceding claims, wherein the piston head (10) is substantially cylindrical in shape, and / or wherein the piston rod (11) is substantially cylindrical in shape, and / or wherein the additional piston rod (16) is substantially cylindrical in shape,and / or wherein the diameter of the piston rod (11) is substantially equal to the diameter of the additional piston rod (16).

4. A braking system (1) according to any one of the preceding claims, wherein the piston head (10) comprises an annular seal (42) extending circularly about the piston head (10), wherein the annular seal (42) is interposed between the piston head (10) and the cylinder (6), wherein the annular seal (42) is configured to prevent a flow of braking fluid from the reaction chamber (12) to the action chamber (13), in particular during the actuation of the electro-hydraulic actuation device (3), but to allow a flow of braking fluid from the action chamber (13) to the reaction chamber (12), in particular during the actuation of the hydraulic actuation device (14), and / or wherein, preferably, the annular seal (42) is a lip seal.

5. A braking system (1) according to any one of the preceding claims, wherein the hydraulic actuation device (14) is fluidly connected to the action chamber (13) by means of the second hydraulic pipe (15).

6. A braking system (1) according to any one of the preceding claims, wherein the second hydraulic pipe (15) extends passing through the cylinder (6), in a transverse direction with respect to the actuation axis (8), and / or wherein the second hydraulic pipe (15) comprises an inlet portion (19) and an orifice (20), wherein the inlet portion (19) has a larger fluid passage section than the orifice (20), wherein the inlet portion (19) and the action chamber (13) are fluidly connected to each other by means of the orifice (20), and / or wherein the inlet portion (19) extends projecting from the cylinder (6), preferably a radial direction with respect to the actuation axis (8).

7. A braking system (1) according to any one of the preceding claims, wherein the first hydraulic pipe (4) leads into the reaction chamber (12) of the cylinder (6), and / or wherein the cylinder (6) forms the first hydraulic pipe (4), and / or wherein the first hydraulic pipe (4) extends passing through the cylinder (6), in a transverse direction with respect to the actuation axis (8), and / or wherein the first hydraulic pipe (4) comprises an inlet portion (19) and an orifice (20), wherein the inlet portion (19) has a larger fluid passage section than the orifice (20),wherein the inlet portion (19) and the reaction chamber (12) are fluidly connected to each other by means of the orifice (20), and / or wherein the inlet portion (19) extends projecting from the cylinder (6), preferably a radial direction with respect to the actuation axis (8).

8. A braking system (1) according to any one of the preceding claims, comprising a housing structure (24) connected to the cylinder (6), wherein the electromechanical actuator (9) is housed inside the housing structure (24), wherein the electromechanical actuator (9) comprises a screw-nut screw system (25) comprising a screw (26) and a nut screw (27), wherein the nut screw (27) is externally screwed to the screw (26), and wherein a rotation of the nut screw (27) about the actuation axis (8) corresponds to a translation of the screw (26) along the actuation axis (8), wherein the electromechanical actuator (9) comprises an electric motor (28) mechanically connected to the nut screw (27) so as to transfer mechanical power to the nut screw (27), wherein the screw-nut screw system (25) is positioned coaxially to the actuation axis (8), or wherein the screw (26) is fixed to the piston rod (11) opposite to the piston head (10).

9. A braking system (1) according to any one of the preceding claims, comprising a valve (36), preferably a by-pass valve, positioned inside the cylinder (6), wherein the valve (36) is configured to allow a flow of braking fluid from the second hydraulic pipe (15) to the first hydraulic pipe (4) during the actuation of the hydraulic actuation device (14), wherein the valve (36) is configured to prevent a flow of braking fluid from the first hydraulic pipe (4) to the second hydraulic pipe (15), in particular when the piston (7) is not positioned in a stroke start position, wherein, preferably, the braking system (1) is configured so that the positioning of the piston (7) in its stroke start position corresponds to an opening of the valve (36), and wherein, preferably, the valve (36) is configured to allow a flow of over-pressurized braking fluid from the reaction chamber (12) to the action chamber (13) when the piston (7) is in the stroke start position.

10. A braking system (1) according to claim 9, wherein the valve (36) is positioned at the piston head (10), preferably integrated inside the piston head (10),wherein the piston head (10) forms a passage pipe (37) extending to pass through the piston head (10), wherein the passage pipe (37) fluidly connects the action chamber (13) to the reaction chamber (12), wherein the valve (36) comprises an adjustment member (38) positioned at the passage pipe (37), wherein the adjustment member (38) is configured to open or close the passage pipe (37) so as to prevent or allow a flow of braking fluid through the passage Pipe (37), wherein, preferably, the adjustment member (38) is positioned coaxially to the actuation axis (8), and wherein, preferably, the adjustment member (38) is elastically biased to close the passage pipe (37) through elastic means (39) interposed between the adjustment member (38) and the additional piston rod (16).

11. A braking system (1) according to claim 10, comprising an abutment pin (40) configured to act as an abutment for the adjustment member (38) of the valve (36), wherein the abutment pin (40) is positioned opposite to the elastic means (39), compared to the abutment member (38), wherein the abutment pin (40) is positioned in the action chamber (13), facing the piston head (10), preferably transversely to the actuation axis (8), wherein the abutment pin (40) is positioned inside a longitudinal through groove (41) formed in the piston rod (11) and extending along the actuation axis (8), wherein the pin (40) is positioned at the stroke start position of the piston (7), so that when the piston (7) is in the stroke start position, the adjustment member (38) abuts against the pin (40), opening the passage pipe (37).

12. A braking system (1) according to any one of the preceding claims, wherein the piston head (10) comprises an action pressure surface (17) facing the action chamber (13), and a reaction pressure surface (18) facing the reaction chamber (12), where the ratio of the area of the action pressure surface (17) to the area of the reaction pressure surface (18) is between 0.90:1.00 and 1.00:0.90, or is between 0.95:1.00 and 1.00:0.95, or wherein the area of the action pressure surface (17) is substantially equal to the area of the reaction pressure surface (18).

13. A braking system (1) according to any one of the preceding claims, wherein thehydraulic actuation device (14) comprises a hydraulic cylinder (29) and a hydraulic piston (30) movable inside the hydraulic cylinder (29) to form a delivery chamber (32) inside the hydraulic cylinder (29), wherein the delivery chamber (32) is fluidly connected to the positive displacement pump (5), preferably to the cylinder (6) of the electro-hydraulic actuation device (3), by means of the second hydraulic pipe (15), wherein the hydraulic actuation device (14) comprises a brake pedal (31) actuatable by a driver, wherein the brake pedal (31) is connected to the hydraulic piston (30), and wherein an actuation of the brake pedal (31) by a driver corresponds to an actuation of the hydraulic piston (30) inside the hydraulic cylinder (29).

14. A braking system (1) according to any one of the preceding claims, comprising flow control means (33) configured to manage and control the transport of braking fluid inside the braking system (1), wherein the control means (33) comprise a control unit (34) and a plurality of sensors adapted to detect the operation of the braking system (1), and preferably any malfunction or failure of the electro-hydraulic actuation device (3), wherein the control unit (34) is configured to receive and process the detections performed by the plurality of sensors, and wherein the control unit (34) is configured to allow an actuation of the hydraulic actuation device (14) and command the transport of braking fluid at the second hydraulic pipe (15) upon the detection of a malfunction or failure of the electro-hydraulic actuation device (3).

15. A braking system (1) according to claim 14, wherein the flow control means (33) comprise a manifold (35) configured to transport the hydraulic fluid, and configured to prevent a transport of the hydraulic fluid through the second hydraulic pipe (15) when the electro-hydraulic actuation device (3) is in normal operation, and transport the hydraulic fluid through the second hydraulic pipe (15) upon the detection of a malfunction or failure of the electro-hydraulic actuation device (3), wherein the flow control means (33) comprise a braking feel simulator device fluidly connected to the manifold (35), and wherein, under normal operating conditions of the electro-hydraulic actuation device (3), the control unit (34) is configured to command the transport, by means of the manifold (35), of the braking fluid pressurized by the brake pedal (31) towards the brakingfeel simulator device.

16. A braking system (1) according to any one of the preceding claims, comprising:- a plurality of braking assembly (2) configured to apply a braking force to respective wheels or axles of a vehicle;- a plurality of electro-hydraulic actuation devices (3), connected to the plurality of braking assemblies (2), respectively, by means of respective first hydraulic pipes (4) and configured to actuate the plurality of braking assemblies (2); wherein the hydraulic actuation device (14) comprises a hydraulic cylinder (29) and a hydraulic piston (30) movable inside the hydraulic cylinder (29), so as to form a delivery chamber (32) inside the hydraulic cylinder (29), wherein the delivery chamber (32) is fluidly connected to the respective positive displacement pumps (5), preferably to the respective cylinders (6), of the plurality of electro-hydraulic actuation devices (3), by means of a respective second hydraulic pipe (15), wherein the hydraulic actuation device (14) comprises a brake pedal (31) actuatable by a driver, wherein the brake pedal (31) is connected to the hydraulic piston (30), and wherein an actuation of the brake pedal (31) by a driver corresponds to an actuation of the hydraulic piston (30) inside the hydraulic cylinder (29), wherein the braking system (1) further comprises at least one control unit (34) and a plurality of sensors adapted to detect the operation of the braking system (1) and a possible malfunction or failure of the electro-hydraulic actuation device (3), in particular of the electro-mechanical actuator (9), wherein the at least one control unit (34) is configured to receive and process the detections performed by the plurality of sensors, and wherein the at least one control unit (34) is configured to allow an actuation of the hydraulic actuation device (14) and command the transport of the braking fluid at a respective second hydraulic pipe (15) upon the detection of a malfunction or failure of the electro-hydraulic actuation device (3), wherein the braking system (1) further comprises a single manifold (35) configured to transport the hydraulic fluid to the plurality of electro-hydraulic actuation devices (3) and the plurality of braking assemblies (2), and wherein the at least one control unit (34) is configured to prevent, by means of the single manifold (35), the transport of the hydraulic fluid through the second hydraulic pipes (15) when the electro-hydraulic actuation devices (3) are in normal operation, and transport, by means of the single manifold (35), the hydraulic fluid through the second hydraulic pipes (15) upon the detection of a malfunction or failure of the plurality ofelectro-hydraulic actuation devices (3).

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