ABS device for a hydraulic braking system of a bicycle, motorcycle or light vehicle

Abstract

The invention provides an ABS device for a hydraulic braking system of a bicycle or motorcycle, comprising an electrically actuated valve unit (13) switchable between a first operating state in which a master cylinder (2) associated with a brake lever is connected to an actuator cylinder (3) of a brake device, and a second operating state in which said connection is interrupted and the actuator cylinder (3) is connected to a fluid accumulator (9). An electronic control device (E) is configured to control the position of the moving element (11) of the fluid accumulator (9), both during ABS activation and during ABS deactivation, so as to cause a non-abrupt, but gradual, change in pressure (CP) in the connecting line (8) to the actuator cylinder (3). Abstract figure: FIG. 1.

Description

Title of the invention: ABS device for a hydraulic braking system of a bicycle, motorcycle or light vehicle. Technical field

[0001] The present invention relates to an ABS device for a hydraulic braking system of a cycle or motorcycle, for example for an electric bicycle or a light two- or three-wheeled electric vehicle, of the type comprising: • an inlet, to be hydraulically connected to a master cylinder associated with a brake lever, • an outlet, to be hydraulically connected to an actuator cylinder associated with a brake device, • a fluid accumulator, comprising an accumulation chamber defined by a movable element within a cavity, said movable element being normally in a starting position corresponding to a minimum volume of the accumulation chamber, • an electrically actuated valve unit switchable between: • a first operating state, in which said inlet and said outlet communicate with each other and said fluid accumulator chamber is isolated, and • a second operating state, in which communication between said inlet and said outlet is interrupted, and the accumulation chamber of said fluid accumulator is in communication with said outlet, and • an electronic control device, configured to detect a state in which activation of an ABS function is required and which, in said state, is further configured to cause a switching of said valve unit, from the first operating state to the second operating state, and to permit movement of the moving element of the fluid accumulator in a direction corresponding to an increase in the volume of the accumulation chamber, in order to cause a decrease in pressure in the connecting line between said outlet and the actuator cylinder of the brake device. Technical background

[0002] An ABS device of the type indicated above is for example described and illustrated in document EP 3 789 256 Bl.

[0003] Generally speaking, ABS devices specifically designed for hydraulic braking systems for bicycles, particularly for electrically assisted bicycles, have been under development for a long time. The solutions proposed in the past are fundamentally of two different types.

[0004] A first type of solution provides a first hydraulic line for the connection between the master cylinder associated with the brake lever and the actuating cylinder associated with the brake device (typically, a disc brake caliper), and a second hydraulic line for the connection of the actuating cylinder of the brake device with the accumulation chamber of a passive fluid accumulator, comprising a movable element that can move against the action of a spring under the effect of the pressurized fluid entering the accumulator. An electrically actuated valve, normally open, is interposed in the first hydraulic line to allow fluid flow from the master cylinder, associated with the brake lever, to the actuating cylinder, associated with the brake device, during normal braking.The second hydraulic line also includes an electrically actuated valve which is normally closed, so as to isolate the fluid accumulator from the brake device's actuator cylinder.

[0005] A state in which activation of the ABS function is required is normally detected by means of a sensor configured to detect a decrease in the rotational speed of the wheel to which the brake device is associated (generally the front wheel of the bicycle), indicative of an imminent wheel lock-up. Alternatively, the need to activate the ABS function is detected by checking when the rear wheel of the bicycle tends to lift off the ground, by monitoring the load acting on the rear wheel axle. Another way to detect the need for ABS intervention is to directly monitor the pressure applied to the brake device's actuator cylinder.

[0006] When the ABS function is to be activated, in known solutions of this first type, an electronic control device causes the electrically actuated valve interposed in the first hydraulic line to close, so as to isolate the master cylinder, associated with the brake lever, from the actuating cylinder, associated with the brake device, and at the same time, the electrically actuated valve interposed in the second hydraulic line is opened, so as to allow the flow of fluid from the actuating cylinder of the brake device to the accumulation chamber of the fluid accumulator.

[0007] An example of an ABS device of this first type has been described and illustrated in document DE 19508915 AL. Other examples of ABS devices of this type have been described in documents DE 101 58 382 Al, EP 2 943 395 Bl, WO 2017 / 115171 A2, WO 2019 / 159029 Al, EP 3 753 835 Bl and EP 3 789 256 BL

[0008] With further reference to the prior art, a second type of solution provides for a single hydraulic line for the connection between the master cylinder associated with the brake lever and the actuating cylinder associated with the brake device, and an ABS device interposed in said hydraulic line and essentially constituting an active type of fluid accumulator, in which the movement of the moving element of the accumulator in both directions is positively controlled by an electric motor. The accumulation chamber of said device is in permanent communication with the downstream section of the hydraulic line, connected to the actuating cylinder of the brake device.Simultaneously, the accumulation chamber of the device is also connected to the upstream section of the hydraulic line, communicating with the master cylinder associated with the brake lever, with the interposition of a check valve comprising a shutter elastically returned to a closed position, so as to allow fluid flow only from said downstream section of the hydraulic line to said upstream section. The moving element of the fluid accumulator is configured so as to engage the shutter of said check valve and to hold it in an open state when the moving element of the device is in its starting position.

[0009] In devices of this second type, during normal braking, the fluid flows from the master cylinder associated with the brake lever to the actuator cylinder associated with the brake device, passing through the device's accumulation chamber, since the non-return valve is held open by the moving element of the device, which is in its starting position. When the need to activate an ABS function is detected (in one of the ways described above), the electric motor controlling the moving element commands the moving element to move away from its starting position, so as to cause the non-return valve to close and the volume of the accumulation chamber to increase, resulting in a decrease in the pressure of the brake device's actuator cylinder, with the consequence of a reduction or cancellation of the braking action.

[0010] An example of a solution of this second type is described in document EP 3 789 256 Bl. Other examples of solutions of this type are described in documents EP 2 985 198 Bl, US 4 275 934 A and US 2020 / 324752 AL. The same applicant has developed solutions of this type, which have been described in documents EP 4 132 841 B and EP 4 132 821 BL.

[0011] All the aforementioned prior solutions are effective in preventing the risk of wheel lock-up due to loss of traction between the wheels and the ground during braking. However, there is a need for further improvements in this area in various respects.

[0012] A first requirement is to produce an ABS device that is as simple as possible in its construction, lightweight and inexpensive.

[0013] Another important requirement is to ensure reliable operation of the device in all operating states, always guaranteeing user safety, even in the event of failure of the ABS device, ensuring in particular the complete operation of the braking system even when the ABS device is defective or in the event of depletion of the charge of the electric supply battery with which the vehicle is equipped or, more generally, in a state in which, for any reason, the electrical supply to the ABS device is lost.

[0014] Another important need is to reduce as much as possible the energy required to activate the ABS device.

[0015] An ABS device of the type indicated at the beginning of this description is described and illustrated in document EP 3 789 256 B1 cited above. In this prior art solution, an electric actuator, in the form of a solenoid, is also associated with the fluid accumulator, but its sole function is to push the moving element of the fluid accumulator back to its starting position when the ABS function is no longer required, thereby causing the fluid to flow out of the fluid accumulator, without the need for a spring to return the moving element to its starting position. However, this prior art solution is complex and expensive and does not allow for precise control of the pressure in the downstream line connected to the brake device's actuator cylinder, on which the ABS effect depends.

[0016] In order to remedy the aforementioned drawbacks, the applicant has already proposed certain solutions, which are the subject of Italian patent applications IT 10 2023 0000 14 319 and IT 10 2023 000027030, both still secret at the filing date of this application. However, further improvements are needed in this area.

[0017] An ABS device according to the preamble of claim 1 is also known from US document 2023 / 234544 A1. This document (see in particular paragraphs 0063 and 0064) illustrates a solution in which the pressure reduction upon activation of the ABS is instantaneous and in which the restoration of pressure is also practically instantaneous, since it occurs by means of a spring following an interruption, without any modulation, of the current supply to a solenoid.

[0018] Another solution is known from document JP 2006 069303 A.

[0019] The main objective of the present invention is to efficiently solve all the problems of the prior art that have been mentioned above.

[0020] In particular, a first objective of the invention is to produce an ABS device that is efficient in its operation, simple in its construction and inexpensive.

[0021] Another objective of the invention is to produce an ABS device which guarantees total safety for the user in all operating states, ensuring the proper functioning of the braking system even when the ABS device is defective, i.e. deprived of electrical power.

[0022] Another objective of the invention is to provide an ABS device that requires minimal energy consumption to activate the ABS function. Description of the invention

[0023] In order to achieve one or more of the aforementioned objectives, the invention relates to an ABS device having all the characteristics indicated at the beginning of this description, and further characterized in that: • said electronic control device is configured to control the position of the moving element of the fluid accumulator, both during activation of the ABS function and during deactivation of the ABS function, so as to cause a non-abrupt, but progressive, variation in pressure in the line connecting to the actuator cylinder of the brake device, both during activation of the ABS function and during deactivation of the ABS function, • said progressive pressure variation being determined by the electronic control device as a function of: • a first parameter, which is the rotational speed of the wheel to which the braking device is associated, detected or calculated based on a signal emitted by a sensor intended to be associated with the wheel, and also depending on: • a second parameter, which is: • either the pressure in the actuator cylinder (3) of the brake device, • either the vehicle deceleration detected or calculated on the basis of a sensor intended to be associated with the vehicle.

[0024] In a preferred embodiment, the ABS device is further characterized in that: • The switching of said valve unit between the first operating state and the second operating state is controlled by a solenoid which is functionally associated with the moving element of said fluid accumulator and which is configured and arranged in such a way that, when said solenoid is energized, it causes: • both a switching of said valve unit from the first operating state to the second operating state and • the application of a force on said moving element of the fluid accumulator, tending to push the moving element towards its starting position corresponding to a minimum volume of the accumulation chamber, and • When the electronic control device determines the state in which activation of the ABS function is required, the electronic control device is programmed to perform the following operations, which consist of, or in which: • In a first phase, supply a relatively high level of electrical current to the solenoid, so as to switch the valve unit from the first operating state to the second operating state, but pushing the moving element of the fluid accumulator back into its starting position, • in a subsequent second phase, gradually decrease the intensity of the electrical current supplied to said solenoid, so that the valve unit remains in its second operating state, while the moving element of the fluid accumulator moves away from its starting position, so as to cause a gradual decrease in pressure in the connecting line between said outlet and the actuating cylinder of the brake device, • in a subsequent third phase, gradually increase the intensity of the electric current supplied to said solenoid, so that the moving element of the fluid accumulator returns to its starting position, determining a gradual increase in pressure in the connecting line between said outlet and the actuator cylinder of the brake device, while the valve unit remains in its second operating state, • in a subsequent fourth phase, after the moving element of the fluid accumulator has returned to its starting position, and once the ABS function is no longer required, the electronic control device interrupts the supply of electrical current to said solenoid, so that the valve unit returns to its first operating state while the moving element of the fluid accumulator remains in its starting position.

[0025] In the second phase mentioned above, the current flowing in the solenoid is reduced proportionally to the force generated by the fluid on the moving element of The fluid accumulator allows the moving element to shift and thus gradually reduces the pressure on the caliper side, ensuring safe braking. Similarly, when the ABS function is no longer required, the pressure on the caliper side is gradually restored.

[0026] In one example, said valve unit comprises: • a main passageway that connects said entrance to said exit, • a first valve interposed in said main passage between said inlet and said outlet and which is in the open position in said first operating state of the valve unit, • a second valve which controls a connection between said main passage and the accumulation chamber of the fluid accumulator, and which is in the closed position in said first operating state of the valve unit, • an actuator element, movable against the action of a spring under the effect of an excitation of said solenoid so as to simultaneously bring the first valve into a closed position and the second valve into an open position, and in such a way that, in the event of a lack of power supply to the solenoid, the spring associated with the actuator element returns the actuator element to the position in which it keeps the first valve open and the second valve closed, even in the presence of an increase in pressure in said main passage determined by braking.

[0027] The invention also relates to the control method implemented by means of the ABS device defined above. Brief description of the drawings

[0028] Other features and advantages of the invention will become apparent from the following description, with reference to the accompanying drawings, which are provided by way of illustration only and are not intended to be limiting, in which

[0029] [Fig-1]: [Fig.1] is a schematic side view of a bicycle with electric assist. electric, using an ABS device according to the present invention.

[0030] [Fig.2] ; Fig.2 illustrates a diagram of a hydraulic braking system comprising an ABS device according to the invention, in a first state of operation.

[0031] [Fig.3]: The [Fig.3] illustrates a diagram of a hydraulic braking system comprising an ABS device according to the invention, in a second operating state.

[0032] [Fig.4]: The [Fig.4] is a cross-sectional view of an exemplary embodiment of the ABS device according to the invention, in an operating state.

[0033] [Fig.4A]: [Fig.4A] illustrates a detail of [Fig.4], at an enlarged scale,

[0034] [Fig.5]: The [Fig.5] is a cross-sectional view of an exemplary embodiment of the ABS device according to the invention, in a different operating state.

[0035] [Fig.5A]: [Fig.5A] illustrates a detail of [Fig.5], at an enlarged scale.

[0036] [Fig.6] : The [Fig.6] is a cross-sectional view of an exemplary embodiment of the ABS device according to the invention, in a different operating state.

[0037] [Fig.6A]: [Fig.6A] illustrates a detail of [Fig.6], at an enlarged scale.

[0038] [Fig.7]: The [Fig.7] is a cross-sectional view of an exemplary embodiment of the ABS device according to the invention, in a different operating state.

[0039] [Fig.7A]: [Fig.7A] illustrates a detail of [Fig.7], at an enlarged scale.

[0040] [Fig.8]: The [Fig.8] is a cross-sectional view of an exemplary embodiment of the ABS device according to the invention, in a different operating state.

[0041] [Fig.9]: The [Fig.9] is a schematic diagram which shows the method of controlling the current supplied to the solenoid of the ABS device according to the invention.

[0042] [Fig. 10]: The [Fig. 10] shows the variation of the indicative signals of the vehicle speed, the rotational speed of the vehicle's front wheel, an indicative factor of the front wheel slip relative to the ground, the pressure in the master cylinder and the pressure in the actuator cylinder of the brake device, before and during the activation of an ABS function. Detailed description

[0043] Fig. 1 schematically shows a bicycle B, comprising a frame T which rotatably supports a crankset unit P, connected by a chain drive CH to the hub of a rear wheel R2 which is rotatably supported by the frame T. An electric motor M is associated with the hub of the rear wheel R2 to assist the cyclist's pedaling. The frame T includes a head tube which rotatably supports a stem whose upper end is connected to a handlebar H and whose lower end is connected to a front fork of the bicycle, which rotatably supports a front wheel RL. A disc brake device F is associated with the wheel RI, which includes a disc D rotatably connected to the hub of the front wheel RI, and a hydraulically operated brake caliper C, supported by one of the two arms of the front fork of the bicycle. Fig.[l] does not show the braking device associated with the rear wheel R2, which could also be, for example, a hydraulically operated disc brake device.

[0044] The brake device F associated with the front wheel is controlled by a hydraulic braking system which is described in detail below, with reference to Figures 2 and 3, and which includes an ABS device 1, also described in detail below.

[0045] Figure 1 shows an example in which the ABS device 1 is supported by one of the two arms of the bicycle's front fork, near the disc brake device F associated with the front wheel RI. However, the arrangement of the ABS device on the bicycle may also be different. For example, the ABS device may be mounted inside one of the tubes that form part of the frame T, as shown in patent DE 10 2019 118 949 A1, of which the applicant is a joint holder, or inside the steering stem, as shown in patent IT 102023000027039 of the applicant (which is not yet publicly available at the date of the present invention).

[0046] With reference to Figures 2 and 3, reference number 1 designates in its entirety the hydraulic braking system of the bicycle, comprising a master cylinder 2, associated in any known way with a brake lever of a bicycle (not illustrated), an actuator cylinder 3, associated in any known way with the brake device F, and an ABS device, schematically represented in its entirety by reference number 4.

[0047] The ABS device 4 includes an inlet 5 hydraulically connected to the master cylinder 2 of the brake lever by means of a hydraulic line 6, and an outlet 7 hydraulically connected to the actuator cylinder 3 of the brake caliper by means of a hydraulic line 8.

[0048] The ABS device 4 includes a fluid accumulator 9 having an accumulation chamber 10 defined by a movable element 11 which, in the example, is a piston with a rod 12. The piston 11 is movable within a cavity in the body of the fluid accumulator 9 and is normally in a starting position (illustrated in [Fig.2]) corresponding to a minimum volume of the accumulation chamber 10.

[0049] The ABS 4 device further comprises a valve unit, indicated as a whole by reference number 13, electrically actuated, switchable between a first operating state and a second operating state.

[0050] In the first operating state of the valve unit 13, illustrated in [Fig. 2], the valve unit 13 connects the inlet 5 and the outlet 7 to each other, so that, in this state, the braking system is able to function normally, allowing the user to activate the brake caliper C ([Fig. 1]) by operating the brake lever. The valve unit 13 is normally maintained in this first operating state, illustrated in [Fig. 2], by elastic means 14.

[0051] The valve unit 13 can be switched, by energizing a solenoid 15 (described in more detail below), from the first operating state illustrated in [Fig. 2] to the second operating state illustrated in [Fig. 3], in which communication between the inlet 5 and the outlet 7 is interrupted and the chamber accumulation 10 of fluid accumulator 9 enters communication with output 7.

[0052] The power supply to the solenoid 15 is controlled by an electronic control device E of the ABS device. The electronic control device E is configured to detect a state in which activation of an ABS function is necessary, by receiving a signal S indicating this need from a sensor SE (see [Fig. 1]), of any known type, with which the bicycle is equipped, adapted to allow the detection or calculation of the angular velocity of rotation of the bicycle's front wheel RI. In the example of [Fig. 1], the sensor SE is located near the disc brake D of the front wheel RL

[0053] The main feature of the invention lies in the fact that the electronic control device E is configured to control the position of the moving element 11 of the fluid accumulator 9, both during an activation of the ABS function and during a deactivation of the ABS function, so as to cause a non-abrupt, but progressive, variation of the pressure in the line connecting to the actuator cylinder 3 of the brake device.

[0054] The progressive pressure variation is determined by the electronic control device as a function of two parameters. The first parameter is the rotational speed of the wheel RI to which the brake device is associated, detected or calculated based on the signal S emitted by the sensor SE. The second parameter is either the force applied to the brake device actuating lever (or a parameter correlated to it, such as the pressure in the master cylinder 2), or the vehicle's deceleration, detected or calculated from a sensor intended to be associated with the vehicle (for example, an accelerometer or an inertial platform).

[0055] The aforementioned characteristics also apply in the case where the ABS device is configured differently from that illustrated in Figures 2 and 3, for example also to an ABS device having a first valve to control the communication between the master cylinder 2 and the actuator cylinder 3 of the brake device, and a second valve to control the communication of the chamber 10 of the fluid accumulator 9 with the connecting line 8 to the actuator cylinder (3).

[0056] However, the implementation illustrated schematically in Figures 2 and 3 constitutes a preferred embodiment of the invention.

[0057] With further reference to Figures 2 and 3, when the electronic control unit E determines, based on the signal S indicating the angular speed of the front wheel RI, the need to activate the ABS function, the electronic control unit E supplies electrical current to the solenoid 15, in the manner that will be described in more detail below, in order to cause the valve unit 13 to pass through from its first operating state illustrated in [Fig.2] to its second operating state illustrated in [Fig.3].

[0058] In the preferred embodiment of the invention, the solenoid 15 which controls the switching of the valve unit 13 is a solenoid which is functionally associated with the moving element 11 of the fluid accumulator 9 and which is configured and arranged in such a way that, when activated, it tends to apply to the moving element 11 of the fluid accumulator 9 a force Fl tending to maintain the moving element 11 in its starting position, corresponding to the minimum volume of the accumulation chamber 10.

[0059] Consequently, the solenoid 15 is capable of simultaneously controlling both the switching of the valve unit 13 (in the manner which will be described in detail below) and a thrust applied to the moving element 11 of the fluid accumulator 9, tending to push the moving element 11 towards its starting position corresponding to the minimum volume of the accumulation chamber 10.

[0060] In a preferred embodiment, as will become clear below, the solenoid 15 is mounted coaxially around the fluid accumulator 9 in a position where the latter is also able to cooperate with an actuator element (described in detail below) which controls the operating state of the valve unit 13.

[0061] A pressure sensor PI is capable of detecting the pressure in the actuator cylinder 3 of the brake caliper and of sending an indicative signal of the detected pressure to the electronic control device E.

[0062] The operation of the ABS device shown schematically in figures 2 and 3 is as follows.

[0063] During normal use of the bicycle, when the ABS function is not required, the solenoid 15 is not supplied with electrical current and the valve unit 13 is in its first operating state illustrated in [Fig. 2]. In this state, an action on the brake lever causes the transfer of fluid from the master cylinder 2, through line 6, the valve unit 13 and line 8, to the actuating cylinder 3 of the brake caliper, which is thus normally activated.

[0064] The spring 14 is configured so as to be able to counterbalance the hydraulic force generated by the pressure exerted on the brake lever, even when the user presses it with maximum force.

[0065] If the electronic control device E determines, based on the signal S indicating the rotational speed of the front wheel RI, the need for intervention by the ABS function, in a first phase, the electronic control device E supplies a relatively high level of electrical current to the solenoid 15, so as to switch the valve unit 13 from the first operating state to the second state of operation, but by pushing the moving element 11 of the fluid accumulator 9 into its starting position illustrated in [Fig.1], despite the fact that the accumulation chamber 9 receives pressurized fluid from the line 8 connected to the actuator cylinder 3 of the brake caliper.

[0066] In a subsequent second phase, the electronic control device gradually decreases the intensity of the electrical current supplied to the solenoid 15, so that the valve unit 13 remains in its second operating state illustrated in [Fig. 3], while the moving element 11 of the fluid accumulator 9 moves away from its starting position (as illustrated in [Fig. 3]), since the force due to the pressure of the fluid arriving in the chamber 10 exceeds the force applied to the moving element 11 by the solenoid 15. The increase in the volume of the chamber 10 causes a gradual decrease in the pressure in the line 8 connected to the actuator cylinder 3 of the brake caliper, resulting in the ABS effect, which prevents wheel lock-up during braking.

[0067] In this phase, the progressive decrease of pressure in line 8 is controlled by the control device E as a function of the signal S indicating the angular speed of the front wheel RI and on the basis of a feedback signal from the sensor PI which detects the pressure in line 8.

[0068] In the aforementioned state, a check valve 13A forming part of the valve unit 13 opens automatically, putting the downstream line 8 connected to the actuator cylinder 3 of the brake caliper into communication with the upstream line 6 connected to the actuator cylinder 2 of the brake lever if, for any reason, the pressure of the downstream line 8 tends to exceed the pressure of the upstream line 6.

[0069] As indicated, the electronic control device E, in the ABS function activation phase, controls the current supplied to the solenoid 15, in order to establish a determined pressure level in the brake caliper actuator cylinder, solely as a function of the rotational speed of the wheel RI, and solely on the basis of a feedback signal provided by the pressure sensor PI, without it therefore being necessary to provide a sensor for the position of the moving element of the fluid accumulator.

[0070] In a subsequent third phase, the electronic control device E gradually increases the intensity of the electric current supplied to the solenoid 15, so that the moving element 11 of the fluid accumulator 9 returns to its starting position (illustrated in [Fig.2]) under the effect of the increase in force Fl applied by the solenoid 15, while the valve unit 13 always remains in its second operating state illustrated in [Fig.3].

[0071] In this phase as well, the control device E controls the current supplied to the solenoid 15 in order to establish a determined pressure level in the cylinder brake caliper actuator, solely based on the rotational speed of the RI wheel, and solely on the basis of a feedback signal provided by the PI pressure sensor.

[0072] In a subsequent fourth phase, after the moving element 11 of the fluid accumulator 9 has returned to its starting position, and once the ABS functionality is no longer required, the electronic control device E interrupts the supply of electrical current to the solenoid 15, so that the valve unit returns to its first operating state illustrated in [Fig. 2], while the moving element of the fluid accumulator 9 remains in its starting position, illustrated in [Fig. 1].

[0073] With reference to figures 4 to 8, which illustrate a concrete example of an embodiment of the invention, the parts illustrated in these figures, which correspond functionally to the parts illustrated in figures 2 and 3, are indicated by the same reference number.

[0074] In this example, the solenoid 15 is housed between an inner tubular sleeve 150 and an outer cylindrical casing 151. Inside the cylindrical casing 151 is arranged a stator body 152 through a central cylindrical cavity 152A in which is mounted in a sliding manner the rod 12 of the piston constituting the movable element 11 of the fluid accumulator 9. Inside the tubular sleeve 150 is arranged a movable armature 153 in the form of a cylindrical body, which is held against the end of the rod 12 opposite the piston 11 by an anti-vibration spring 154.

[0075] The body 16 of the valve unit 13 defines the inlet 5 which can be hydraulically connected to the master cylinder of the brake lever, the outlet 7 which can be hydraulically connected to the actuating cylinder of the brake caliper, and a main passage 17 which puts the inlet 5 in communication with the outlet 7.

[0076] In the body 16 of the valve unit 13 is mounted a cylindrical body 16A in which are arranged the fluid accumulator 9 and two valves VI, V2 which respectively control the communication between the inlet 5 and the outlet 7 and the communication between the outlet 7 and the chamber 10 of the fluid accumulator 9.

[0077] Figure 4 and Figure 4A (which illustrates a detail of Figure 4 at an enlarged scale) show the "rest" state of the ABS device, when the ABS function is not required and solenoid 15 is de-energized. In this state, valves VI and V2 are respectively in an open and a closed state.

[0078] With reference to [Fig.4A], in the illustrated example, the valve VI includes a ball 50 and a spring 51 which tends to return the ball 50 to a closed position on a valve seat 52.

[0079] In the rest state illustrated in Figures 4 and 4A, i.e., when the solenoid is de-energized, the ball 50 is held in an open position, against the action of the spring 51, by one end of a pin 180 which is rigidly connected to an actuator element 18 (see [Fig.4]), in the form of an annular disc, made of ferromagnetic material, which is slidably mounted inside the outer cylindrical housing 151 opposite one end of the solenoid 15. When the solenoid 15 is de-energized, the actuator element 18 is held by springs 14 (interposed axially between the facing surfaces of the solenoid 15 and the actuator element 18) in a position (to the right with reference to Figures 4 to 7) in which the pin 180 holds the ball 50 of the valve VI in the open position, against the action of the spring 51. In this state, the communication between the inlet 5 and the outlet 7 (i.e. between the brake lever and the brake caliper) is therefore open.

[0080] With reference again to [Fig.4A], in the illustrated example, the valve V2 includes a valve obturator consisting of a conical part 180A of the spindle 180, cooperating with a valve seat 180B defined by an annular element 180C mounted inside the body 16A.

[0081] In the state of Figures 4, 4A, i.e. when the solenoid is de-excited, the shutter 180A of the valve V2 is in its closed position, thus preventing communication from the outlet 7 with the accumulation chamber 10 (better seen in [Fig. 4A], which illustrates the active operating state of the ABS device) of the fluid accumulator 9.

[0082] The annular disc constituting the actuator element 18 is made of ferromagnetic material and has a central cylindrical cavity 18A through which the rod 12 of the moving element 11 of the fluid accumulator passes. The annular body constituting the actuator element 18 is rigidly connected to the spindle 180 which controls the valves VI and V2 as described above. The rod 12 of the moving element 11 of the fluid accumulator 9 has a centrally grooved portion 12A to prevent any interference with the spindle 180, so that the movements of the spindle 180 and, with it, of the actuator element 18, as well as the movements of the rod 12 and the moving element 11 of the fluid accumulator, are independent of each other.For the same reason, the piston constituting the moving element 11 of the fluid accumulator 9, which consists of a cylindrical body rigidly connected to the centrally grooved part of the rod 12, has an axial cavity for the passage of the pin 180. The cylindrical body which constitutes the moving element 11 of the fluid accumulator 9 is provided on its outer surface with sealing rings cooperating with the cylindrical wall of the cavity of the body 16A in which the moving element 11 is slidably mounted, and with at least one other internal sealing ring, cooperating with the pin 180.

[0083] The body 16 is also associated with the pressure sensor PI, configured to detect the pressure in the main passage 17, and with an electronic board constituting the electronic control device E.

[0084] As already indicated with reference to Figures 4 and 4A, when the solenoid 15 is de-energized, the ABS function not being required, the actuator element 18 is held by the springs 14 in the position in which the pin 180 keeps valve VI open and valve V2 closed. In this situation, the inlet 5 and the outlet 7 therefore communicate with each other via the main passage 17 and the first valve VI, while the accumulation chamber 10 of the fluid accumulator 9 is isolated from said main passage 17. The cyclist can thus normally operate the brake device F by acting on the brake lever.

[0085] When the electronic control device E (see figures 2, 3) detects the need for intervention of the ABS function, based on the signal S which allows the detection or calculation of the rotational speed of the wheel RI, the electronic control device provides the solenoid 15 with a relatively high current level in order to obtain the displacement of the actuator element 18 in its operating position illustrated in [Fig.5], against the action of the springs 14 and, at the same time, the application of a force F by the movable armature 153 against the rod 12 of the movable element 11 of the fluid accumulator 9, tending to maintain the movable element 11 in the position corresponding to the minimum volume of the accumulation chamber 10.In this state, illustrated in figures 5 and 5A, the movement of the actuator element 18 determines the movement (to the left with reference to the figures) of the spindle 150, resulting in the opening of valve V2 and the closing of valve VI, whose ball shutter 50 is pushed into the closed position by the respective spring 51.

[0086] In this operating state, a decoupling (in the sense of an interruption of communication) occurs between the brake lever side and the brake caliper side, while the output 7 enters into communication, via the valve V2, with the accumulation chamber 10. However, in the state of Figures 5, 5A, the moving element 11 of the fluid accumulator 9 is not able to move away from its starting position, given that the solenoid, powered by a relatively high current level, applies to the rod 12 of the moving element 11, via the moving armature 153, a force sufficient to counteract such a movement.

[0087] Once the operating state illustrated in [Fig. 5] has been reached, i.e., once valves VI, V2 have been switched to the closed and open states, respectively, the electronic control device E can gradually reduce the supply current to the solenoid 15 so that the actuator element 18 remains in the operating position illustrated in [Fig. 7], while that the movable armature 153 exerts a decreasing force against the rod 12, so that the movable element 11 is able to move away from its starting position, thus causing an increase in the volume of the accumulation chamber 10. This state is illustrated in Figures 6 and 6A.

[0088] The progressive reduction of pressure on the caliper side is controlled by the electronic control device solely based on the signal S indicating the rotational speed of the front wheel, and solely on the basis of a feedback signal provided by the pressure sensor PL

[0089] In this state, if, for any reason, the pressure on the brake caliper side tends to become greater than the pressure on the brake lever side, valve VI opens automatically, acting as a safety valve, in order to discharge the excess pressure from the line connected to outlet 7 to the line connected to inlet 5.

[0090] When the ABS effect is no longer required, the electronic control device gradually increases the supply current to the solenoid 15, up to a level high enough for the moving armature 153 to push the rod 12 and, with it, the moving element 11, back towards the starting position, corresponding to the minimum volume of the accumulation chamber. Once this state is reached, the electronic control device E de-energizes the solenoid 15, in order to return the ABS device 4 to the starting state illustrated in [Fig. 4].

[0091] It should be noted that the spring 154 is a relatively weak spring, whose sole function is to hold the movable armature 153 against the rod 12, in order to prevent vibrations of the movable armature 153. In other words, the spring 154 is not capable of acting as a return spring for the movable element 11 to its starting position. This return action, in the ABS device of the present invention, is ensured by the solenoid 15. That is to say, the ABS device 4 would be able to function even if the spring 154 were removed.

[0092] It should also be noted that the return action of the solenoid 15 is not essential to guarantee a safe state, because it is the actuator element 18 which, under the effect of the safety springs 14, in the absence of power supply, returns the system to the starting state (see figures 7 and 7A).

[0093] Consequently, the spring 14 (or springs 14) associated with the actuator element 18 is configured so that, in the absence of excitation of the solenoid 15, the actuator element 18 remains in a position in which it keeps the first valve VI open and the second valve V2 closed, even in the presence of an increase in pressure in the main passage 17 determined by braking, as long as the need for intervention of the ABS function does not arise.

[0094] In the example illustrated in Figures 4 to 8, the spring 154 is interposed between one end of the movable armature 153 protruding outside the device 4 and a wall (not visible on the drawings) formed by a plastic cover whose sole function is to provide a reaction to the spring 154 and to ensure sealing.

[0095] Fig. 8 shows an overview of the ABS 4 device.

[0096] Figure 9 shows an example of the method for controlling the current supplied to the unit electrically actuated valve of the ABS device during braking, which can be implemented in the electronic control device E of the ABS device. In the case of the embodiments illustrated here by way of example, the method controls the electrical current supplied to the solenoid 15.

[0097] The entire control method illustrated in [Fig. 9] is based on two parameters, namely: the pressure CP in the line connected to the actuator cylinder 3 of the brake device, and the rotational speed co of the front wheel of the vehicle to which the brake device is connected. As an alternative to the pressure CP, the method can be based on the vehicle's deceleration detected by a sensor (e.g., an inertial platform) or calculated, for example, based on the detected vehicle speed.

[0098] In blocks 100 and 200, the signal relating to the pressure CP, coming from the PI sensor, and the signal relating to the rotational speed co, coming from the SE sensor, are processed and filtered, in order to estimate the braking intensity in block 101 and the vehicle speed in block 201.

[0099] Based on the estimation of the braking intensity carried out in block 101, a signal 102 is sent to a supervisor module El of the electronic control device E in order to progressively modulate the pressure CP (in the example, by sending a signal 300 which controls the current supplied to the solenoid 15 of the ABS device).

[0100] In parallel with signal 102, based on the estimation of braking intensity in block 101 and based on the estimation of vehicle speed in block 201, in block 103, an estimation of the risk of the vehicle tipping forward is performed, from which a signal 104 indicating said risk of tipping is derived, which is sent to the EL supervisor module

[0101] In block 202, based on the vehicle speed estimate made in block 201, and based on the value of the front wheel rotation speed processed in block 200 (line 200A), an estimate of the front wheel slip relative to the ground is made.

[0102] Based on the estimation carried out in block 202, based on signal 104 relating to the risk of tipping forward and based on signal 200A relating to the rotational speed of the front wheel, in block 203, the state of adhesion of the front wheel to the ground is estimated according to a scale of values ​​comprising at least one value corresponding to "high adhesion" and one value corresponding to "low adhesion".

[0103] The estimation carried out in block 203 triggers the sending, to the supervisor module El, of a signal 204 indicating a target value of the pressure CP in the actuator cylinder 3 of the brake device.

[0104] The supervisor module El, based on signal 102 indicating the braking intensity, signal 104 indicating the risk of the vehicle tipping forward, signal 202A indicating the estimated degree of grip of the vehicle's front wheel relative to the ground, and signal 204 indicating the target value of the CP pressure, is able to output a signal 300 which controls the supply current of the solenoid 15 in order to obtain the desired CP pressure, according to a loop process, based on a feedback signal of the CP pressure detected by the PL sensor

[0105] In this way, the system according to the invention is able to optimally control braking, by progressively varying the CP pressure during the intervention of the ABS function and during the recovery of the CP pressure when the ABS function is deactivated.

[0106] Fig. 10 shows the variation over time of certain parameters (vehicle speed V, front wheel rotation speed co, degree of wheel adhesion to the ground, LP pressure in the master cylinder 2 associated with the brake lever and CP pressure in the actuator cylinder 3 of the brake device) during so-called "panic" braking (i.e. sudden and violent braking due to an unforeseen situation), on a slippery surface.

[0107] The diagram in the upper part of [Fig. 10] shows the variation over time of the vehicle speed indicator signal V and the front wheel rotation speed indicator signal co, before and after an instant to at which a user operates the front wheel brake device.

[0108] Up to time t0, the two signals coincide, whereas after time t0 the wheel rotation speed co decreases more abruptly, indicating a tendency for the wheel to lock up, which triggers the intervention of the ABS function. Following this intervention, the wheel rotation speed co begins to increase again, returning to a variation corresponding to the variation in vehicle speed V.

[0109] The diagram in the middle of [Fig. 10] shows the corresponding variation in the degree of wheel adhesion to the ground during braking.

[0110] The diagram in the lower part of [Fig. 10] shows the corresponding variations of the LP pressure in the master cylinder 2 associated with the brake lever and of the CP pressure in the actuating cylinder 3 of the brake device (generally the brake caliper). This diagram shows that the system is configured to implement a non-abrupt, but gradual, variation of the CP pressure, both when the ABS function intervenes and when it ceases to act.

[0111] Naturally, without prejudice to the principle of the invention, the construction details and embodiments may vary considerably from what has been described and illustrated by way of example only, without departing from the scope of the present invention, as defined in the attached claims.

Claims

1. Demands ABS device for a hydraulic braking system of a bicycle, motorcycle, or light vehicle, comprising: • an inlet (5), to be hydraulically connected to a master cylinder (2) associated with a brake lever, • an outlet (7) to be hydraulically connected to an actuator cylinder (3) associated with a brake device which is intended to be associated with a wheel (RI) of the vehicle, • a fluid accumulator (9) having an accumulation chamber (10) defined by a movable element (11) inside a cavity, said movable element (11) being normally in a starting position corresponding to a minimum volume of the accumulation chamber (10), • an electrically actuated valve unit (13) switchable between: • a first operating state, in which said inlet (5) and said outlet (7) communicate with each other and said accumulation chamber (10) of the fluid accumulator (9) is isolated, and • a second operating state in which communication between said inlet (5) and said outlet (7) is interrupted and the accumulation chamber (10) of said fluid accumulator (9) is in communication with said outlet (7), and • an electronic control device (E) configured to detect a state in which activation of an ABS function is required and which, in said state, is further configured to cause a switching of said valve unit (13) from the first operating state to the second operating state, and to permit movement of the moving element (11) of the fluid accumulator (9) in a direction corresponding to an increase in the volume of the accumulation chamber (10), in order to cause a decrease in pressure in the connecting line between said outlet (7) and the actuator cylinder (3) of the brake device, said ABS device being characterized in that: • said electronic control device is configured to control the position of the moving element (11) of the fluid accumulator (9), both during activation of the ABS function and during deactivation of the ABS function, so as to cause a non-abrupt, but progressive variation of the pressure (CP) in the line (8) connecting to the actuator cylinder (3) of the brake device (F), both during activation of the ABS function and during deactivation of the ABS function, • said progressive pressure variation being determined by the electronic control device (E) as a function of: • a first parameter, which is the rotational speed (œ) of said wheel (RI) to which the braking device is associated, detected or calculated from a signal emitted by a sensor (SE) intended to be associated with the wheel, and also as a function of: • a second parameter, which is: • either the pressure in the actuator cylinder (3) of the brake device, • either the vehicle deceleration detected or calculated on the basis of a sensor intended to be associated with the vehicle.

2. ABS device according to claim 1, characterized in that: • The switching of said valve unit (13) between the first operating state and the second operating state is controlled by a solenoid (15) which is functionally associated with the moving element (11) of said fluid accumulator (9) and which is configured and arranged such that, when said solenoid (15) is energized, it causes: • both a switching of said valve unit (13) from the first operating state to the second operating state, • and the application of a force (F) on said moving element (11) of the fluid accumulator (9) tending to push the moving element (11) towards its starting position corresponding to a minimum volume of the accumulation chamber (10), • when the electronic control device determines said state in which activation of the ABS function is required, the electronic control device (E) is programmed to perform the following operations consisting of or in which: • in a first phase, supply a relatively high level of electrical current to said solenoid (15), so as to switch the valve unit (13) from the first operating state to the second operating state, but pushing the moving element (11) of the fluid accumulator (9) into its starting position, • in a subsequent second phase, progressively decrease the intensity of the electric current supplied to said solenoid (15), so that the valve unit (13) remains in its second operating state, while the moving element (11) of the fluid accumulator (9) moves away from its starting position, so as to cause a progressive decrease in the pressure in the

3. connecting line between said outlet (7) and the actuator cylinder (3) of the brake device, • in a subsequent third phase, progressively increase the intensity of the electrical current supplied to said solenoid (15), such that the moving element (11) of the fluid accumulator (9) returns to its starting position, determining a progressive increase in pressure in the connecting line between said outlet (7) and the actuator cylinder (3) of the brake device, while the valve unit (13) remains in its second operating state, • in a subsequent fourth phase, after the moving element (11) of the fluid accumulator (9) has returned to its starting position, and once the ABS function is no longer required, the electronic control device (E) interrupts the supply of electrical current to said solenoid (15), so that the valve unit (13) returns to its first operating state while the moving element (11) of the fluid accumulator (9) remains in its starting position. ABS device according to claim 1, characterized in that said electronic control device (E) is configured to receive an indicative signal of the pressure in the connecting line (8) to the actuator cylinder (3) of the brake device (F), from a sensor (PI) associated with said connecting line (8), and to control, in said second phase and in said third phase, a progressive variation of the pressure in the connecting line (8) to the actuator cylinder (3) of the brake device (F), as a function of an indicative signal (S) of the wheel rotation speed (RI) to which the ABS device is intended to be associated and on the basis of a signal from said pressure sensor (PI).

4. ABS device according to claim 1, characterized in that said valve unit (13) comprises: • a main passage (17) which connects said inlet (5) to said outlet (7), • a first valve (VI) interposed in said main passage (17) between said inlet (5) and said outlet (7) and which is in the open position in said first operating state of the valve unit (13), • a second valve (V2) which controls a connection between said main passage (17) and the accumulation chamber (10) of the fluid accumulator (9), and which is in the closed position in said first operating state of the valve unit (13), • an actuator element (18), movable against the action of a spring (14) under the effect of an excitation of said solenoid (15) so as to simultaneously bring the first valve (VI) into a closed position and the second valve (V2) into an open position, and • such that,In the event of a power failure to supply the solenoid, the spring (14) associated with the actuator element (18) returns the actuator element (18) to the position in which it maintains the first valve (VI) open and the second valve (V2) closed, even in the presence of a pressure increase in said main passage (17) caused by braking.

5. ABS device according to claim 4, characterized in that: • said solenoid (15) is mounted between an inner tubular sleeve (150) and an outer cylindrical housing (151), • inside said inner tubular sleeve (150) are arranged, axially aligned, a stator body (152), and a movable armature (153), mounted slidably inside said inner tubular sleeve (150) and connected to the movable element (11) of the fluid accumulator (9), such that following an excitation of the solenoid (15), the movable armature (153) applies a force (F) to the movable element (11) in the direction of a decrease in the volume of the accumulation chamber (10).

6. ABS device according to claim 5, characterized in that the stator body (152) has a central cylindrical cavity (152A) inside which is slidably mounted a rod (12) which rigidly connects the movable armature (153) to the movable element (11) of the fluid accumulator (9).

7. ABS device according to claim 6, characterized in that: • said valve unit (13) comprises a valve body (16) rigidly connected to said outer cylindrical housing (151) of the solenoid (15), • said actuator element (18) is an annular element interposed axially between one end of said stator body (152) and the body (16) of the valve unit (13), said actuator element (18) being pushed by one or more springs (14) towards a first operating position in which it holds said first valve (VI) open and said second valve (V2) closed, and being able to be returned against the end of said stator body (152) facing it following excitation of the solenoid (15), so as to cause a closure of the first valve (VI) and an opening of the second valve (V2).

8. ABS device according to claim 7, characterized in that said actuator element (18) controls said first valve (VI) and said second valve (V2) by means of an axial spindle comprising a part acting as a valve element of the second valve and a terminal end which controls the position of the valve element of said first valve (VI).

9. A method for controlling an ABS function in a hydraulic braking system of a cycle or motorcycle, in particular a bicycle, wherein: • an inlet (5), to be hydraulically connected to a master cylinder (2) associated with a brake lever, • an outlet (7) to be hydraulically connected to an actuator cylinder (3) associated with a brake device, intended to be associated with a wheel of the vehicle, • a fluid accumulator (9) comprising an accumulation chamber (10) defined by a movable element (11) within a cavity, said movable element (11) normally being in a starting position corresponding to a minimum volume of the accumulation chamber (10), • an electrically actuated valve unit (13), switchable between: • a first operating state,in which said inlet (5) and said outlet (7) communicate with each other and said accumulation chamber (10) of the fluid accumulator (9) is isolated, and • a second operating state in which the communication between said inlet (5) and said outlet (7) is interrupted and the accumulation chamber (9) of said fluid accumulator (9) is in communication with said outlet (7), said method comprising the operation of detecting, by means of an electronic control device (E), a state in which activation of an ABS function is required, and causing, in said state, a switching of said valve unit (13) from the first operating state to the second operating state, also allowing a movement of the moving element (11) of the fluid accumulator (9) in a direction corresponding to an increase in the volume of the accumulation chamber (11), in order to cause a decrease in pressure in the connecting line between said outlet (7) and the actuator cylinder (3) of the brake device, said process being characterized in that: • The method comprises the operation of controlling, by means of said electronic control device (E), the position of the moving element (11) of the fluid accumulator (9), both during an activation of the ABS function and during a deactivation of the ABS function, so as to cause a non-abrupt, but progressive, variation of the pressure (CP) in the connecting line (8) to the actuator cylinder (3) of the brake device (F), both during an activation of the ABS function and during a deactivation of the ABS function, • said progressive pressure variation being determined, by means of said electronic control device (E), as a function of: • a first parameter, which is the rotational speed of said wheel (RI) to which the braking device is associated, detected or calculated on the basis of a signal emitted by a sensor intended to be associated with the wheel (SE), and also as a function of: • a second parameter, which is: • either the pressure (CP) in the actuator cylinder (3) associated with the brake device, • either the vehicle's deceleration detected or calculated from a sensor intended to be associated with the vehicle.

10. The method according to claim 9, characterized in that: • The switching of said valve unit (13) between the first operating state and the second operating state is controlled by a solenoid (15) which is functionally associated with the moving element (11) of the fluid accumulator (9) and which is configured and arranged such that, when said solenoid (15) is energized, it causes: • both a switching of said valve unit (13) from the first operating state to the second operating state, • and the application of a force (F) on said moving element (11) of the fluid accumulator (9) tending to push the moving element (11) towards its starting position, corresponding to a minimum volume of the accumulation chamber (10), • the state in which the activation of an ABS function is required is determined solely on the basis of a signal (S) indicating the rotational speed of the wheel (RI) to which said brake device (F) is intended to be associated, • When the state in which activation of an ABS function is required is determined, the following operations are performed: • in a first phase, supply a relatively high level of electrical current to said solenoid (15), so as to switch the valve unit (13) from the first operating state to the second operating state, but pushing the moving element (11) of the fluid accumulator (9) into its starting position, • in a subsequent second phase, gradually decrease the intensity of the electric current supplied to said solenoid (15), so that the valve unit (13) remains in its second operating state, while the moving element (11) of the fluid accumulator (9) moves away from

11. its starting position, so as to cause a progressive decrease in pressure in the connecting line between said outlet (7) and the actuator cylinder (3) of the brake device, • in a subsequent third phase, progressively increase the intensity of the electrical current supplied to said solenoid (15), so that the moving element (11) of the fluid accumulator (9) returns to its starting position, determining a progressive increase in pressure in the connecting line between said outlet (7) and the actuator cylinder (3) of the brake device, while the valve unit (13) remains in its second operating state, • in a subsequent fourth phase, after the moving element (11) of the fluid accumulator (9) has returned to its starting position, and once the ABS function is no longer required, the electronic control device (E) interrupts the supply of electrical current to said solenoid (15), so that the valve unit (13) returns to its first operating state while the moving element (11) of the fluid accumulator (9) remains in its starting position. A method according to claim 9, characterized in that it comprises the operation of receiving, in said electronic control device (E), a signal (S) indicating the pressure in the connecting line (8) to the actuator cylinder (3) of the brake device (F), from a sensor (PI) associated with said connecting line (8), and the operation of controlling, in said second phase and in said third phase, a progressive variation of the pressure (CP) in the connecting line (8) to the actuator cylinder (3) of the brake device (F) as a function of said signal (S) indicating the rotational speed of the wheel (RI) to which the ABS device is associated and on the basis of a signal from said pressure sensor (PI).

12. A method according to claim 9, characterized in that it comprises a fifth phase to compensate for any fluid leakage from the first valve to the second valve during their switching, by means of a "cleaning" cycle, in which: • the user does not brake, • a current is supplied to the solenoid (15) to open the second valve (V2), • the moving element (11) of the fluid accumulator (9) moves to its starting position, emptying the accumulation chamber (10), • the fluid subsequently flows from the line (8) of the brake device to the line (6) of the brake lever, by means of a discharge function of the first valve (VI).

13. A method according to claim 9, characterized in that it comprises implementing, during activation of the brake device, the by means of said electronic control device (E), the following operations consisting of: • process (100) an indicative signal of said second parameter (CP) to estimate (101) the braking intensity, • process (200) an indicative signal of said first parameter (œ) to estimate (201) the speed of the vehicle, • based on the estimation (101) of the braking intensity, send a signal (102) to a supervisor module (El) of the electronic control device (E) to progressively modulate the pressure (CP) in the actuator cylinder (3) of the brake device, by sending a signal (300) which controls the current supplied to said electrically actuated valve unit, • based on the estimation (101) of the braking intensity, and based on the estimation (201) of the vehicle speed, estimate (103) a risk of the vehicle tipping forward, and send a signal (104) indicating said risk of tipping to the supervisor module (El), • based on the estimate (201) of the vehicle speed and based on a signal (200A) indicative of said first parameter (œ), estimate (202) a degree of slippage of the vehicle wheel relative to the ground, • based on the estimate of the degree of slippage (202), based on the signal (104) indicating the risk of forward tipping and based on the signal (200A) indicating the rotational speed of the vehicle wheel, estimate (203) the state of adhesion of the wheel to the ground according to a scale of values ​​including at least one value corresponding to "high adhesion" and one value corresponding to "low adhesion", • based on the estimation (203) of the degree of adhesion, send to the supervisor module (El) a signal (204) indicating a target value of the pressure (CP) in the actuator cylinder (3) of the brake device, • based on the signal (102) indicating the braking intensity, based on the signal (104) indicating the risk of the vehicle tipping forward, based on from a signal (202A) indicating the estimation of the degree of adhesion of the vehicle wheel to the ground, and on the basis of the signal (204) indicating the target value of the pressure (CP) in the actuator cylinder of the brake device, generate, by means of said supervisor module (El), a signal (300) which controls the current supplied to the electrically actuated valve unit, in order to reach the target pressure (CP) in the actuator cylinder of the brake device, according to a loop process based on a feedback signal of said pressure (CP) detected by a sensor (PI).

Images