ABS device for a hydraulic braking system of a cycle or a motorcycle or a li ht vehicle

Abstract

An ABS device for a hydraulic braking system of a cycle or motorcycle, particularly for bicycles, includes an electrically actuated valve unit (13) that is switchable between a first operating condition in which a master cylinder (2) associated with a brake lever is placed in communication with an actuator cylinder (3) of a brake device, and a second operating condition, in which the aforementioned communication is interrupted and the actuator cylinder (3) of the brake device is placed in communication with a fluid accumulator (9). The switching of the valve unit (13) between the first operating condition and the second operating condition is controlled by a solenoid (15) which is operatively associated with the movable member (11) of the fluid accumulator (9) and which is configured and arranged so that when the solenoid (15) is energized it causes both the switching of the valve unit (13) from the first operating condition to the second operating condition, and also the application of a force (F) on the movable member (11 ) of the fluid accumulator (9) tending to push the movable member (11) to a starting position corresponding to a minimum volume of the accumulation chamber (10) of the fluid accumulator (9).

Description

[0001] ABS device for a hydraulic braking system of a cycle or a motorcycle or a light vehicle”

[0002] ****

[0003] Field of the Invention

[0004] The present invention relates to an ABS device for a hydraulic braking system of a cycle or motorcycle, such as for an electric bicycle or a two- or three-wheeled light electric vehicle, of the type comprising:

[0005] - an inlet, to be hydraulically connected to a master cylinder associated with a brake lever,

[0006] - an outlet, to be hydraulically connected to an actuator cylinder associated with a brake device,

[0007] - a fluid accumulator, having an accumulation chamber defined by a movable member within a cavity, said movable member being normally in a starting position corresponding to a minimum volume of the accumulation chamber,

[0008] - an electrically operated valve unit switchable between:

[0009] - a first operating condition, in which said inlet and said outlet communicate with each other and said fluid accumulator chamber is isolated, and

[0010] - a second operating condition, 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

[0011] - an electronic controller, which is configured to detect a condition in which an activation of an ABS function is required, and which, in said condition, is further configured to cause a switching of said valve unit from the first operating condition to the second operating condition and to enable a movement of the movable member of the fluid accumulator in a direction corresponding to an increase in the volume of the accumulation chamber, so as to cause a decrease in the pressure in the line connecting said outlet and the actuator cylinder of the brake device.

[0012] Prior Art

[0013] An ABS device of the above type is, for example, described and illustrated in EP 3 789 256 B1.

[0014] In general, ABS devices specifically dedicated to hydraulic bicycle braking systems, particularly for pedal-assisted bicycles, have been developed for some time. The solutions proposed in the past are basically of two different types.

[0015] A first type of solution involves a first hydraulic line for the connection between the master cylinder associated with the brake lever and the actuator cylinder associated with the brake device (typically, a disc brake caliper), and a second hydraulic line for the connection of the actuator cylinder of the brake device with the accumulator chamber of a passive-type fluid accumulator, having a movable member that can move against the action of a spring due to the effect of the pressurized fluid entering the accumulator. An electrically actuated normally open valve is interposed in the first hydraulic line to allow a flow of fluid from the master cylinder, associated with the brake lever, to the actuator cylinder, associated with the brake device, during normal braking. The second hydraulic line also includes an electrically actuated valve that is normally closed, so as to isolate the fluid accumulator from the actuator cylinder of the brake device.

[0016] A condition 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 with which the brake device is associated (typically the front wheel of the bicycle), indicative of incipient locking of that wheel. Alternatively, the need to activate the ABS function is detected by checking when the rear wheel of the bicycle tends to come off the ground by monitoring the load acting on the rear wheel axle of the bicycle. Another way to detect the need for ABS function intervention is by directly monitoring the pressure applied to the actuator cylinder of the brake device.

[0017] When the ABS function needs to be triggered, in known solutions of this first type, an electronic controller 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 actuator cylinder, associated with the brake device, and at the same time the electrically actuated valve interposed in the second hydraulic line is caused to open, so as to enable the flow of fluid from the actuator cylinder of the brake device to the fluid accumulation chamber of the fluid accumulator.

[0018] An example of an ABS device of this first type was described and illustrated in DE 19508915 A1. Further examples of ABS devices of this type have been described in DE 101 58 382 A1 , EP 2 943 395 B1, WO 2017 / 115171 A2, WO 2019 / 159029 A1, EP 3 753 835 B1 and EP 3 789 256 B1

[0019] Still with reference to the known technique, a second type of solutions involves a single hydraulic line for connection between the master cylinder associated with the brake lever and the actuator cylinder associated with the brake device and an ABS device interposed in that hydraulic line and basically constituting an active-type fluid accumulator, in which the displacement of the movable member of the accumulator in both directions is positively controlled by an electric motor. The accumulator chamber of such a device is permanently in communication with the downstream section of the hydraulic line, which is connected to the actuator cylinder of the brake device. At the same time, the accumulator chamber of the device is also connected with the upstream section of the hydraulic line, communicating with the master cylinder associated with the brake lever, by the interposition of a unidirectional valve comprising a plug elastically recalled to a closed position, so as to allow a flow of fluid only from said downstream section of the hydraulic line to said upstream section. The movable member of the fluid accumulator is configured to engage the poppet of said one-way valve and maintain it in an open condition when the movable member of the device is in a starting position thereof.

[0020] In devices of this second type, during normal braking, 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, as said one-way valve is kept open by the device's movable member, which is in its starting position. When the need to activate an ABS function is detected (in one of the ways that have been described above), the electric motor controlling the movable member commands a movement of the movable member away from its starting position, so as to cause the one-way valve to close and an increase in the volume of the accumulation chamber, which results in a decrease in the pressure of the actuator cylinder of the brake device, resulting in a decrease or cancellation of the braking action.

[0021] An example of a solution of this second type is described in EP 3 789 256 B1. Further examples of solutions of this type are described in documents EP 2 985 198 B1 , US 4 275 934 A and US 2020 / 324752 A1. The Applicant itself has developed such solutions, which have been described in documents EP 4 132 841 B1 and EP 4 132 821 B1.

[0022] All of the above known solutions are effective in avoiding the risk of wheel locking as a result of a loss of grip between the wheels and the ground during braking. However, there is a need for further refinements in this field in several respects.

[0023] A first need is to make an ABS device that is as simple in construction, lightweight, and low cost as possible.

[0024] A further important need is to ensure reliable operation of the device under all operating conditions, guaranteeing safety for the user at all times, even in the event of a failure of the ABS device, specifically ensuring full operation of the braking system even when the ABS device is failing or in the event that there is a depletion of the charge of the electrical supply battery with which the vehicle is equipped or, more generally, in a condition in which, for whatever reason, the electrical supply to the ABS device fails.

[0025] Still another important need is to reduce as much as possible the energy required to activate the ABS device.

[0026] An ABS device of the type indicated at the beginning of this description is described and illustrated in EP 3 789 256 B1 mentioned above. In such a known solution, the fluid accumulator is also associated with an electric actuator, in the form of a solenoid, which, however, has the sole function of pushing the movable member of the fluid accumulator back to its starting position when the ABS function is no longer needed, so that the fluid flows out of the fluid accumulator, without the need to provide a spring to call the movable member back to its starting position. However, such a known solution is complex and expensive and does not allow precise control of the pressure in the downstream line connected to the actuator cylinder of the brake device, on which the ABS effect depends.

[0027] With a view to solving the aforementioned drawbacks, the Applicant has already proposed a solution, which has been the subject of Italian patent application IT 10 2023 0000 14 319, filed on 10.07.2023 and still secret as of the priority date of the present application. However, there is a need for further improvements in this field. Object of the invention

[0028] The main purpose of the present invention is to effectively solve all the problems of the known technique that have been mentioned above.

[0029] Specifically, a first purpose of the invention is to provide an ABS device that is efficient in operation, constructively simple, and of low cost.

[0030] A further purpose of the invention is to provide an ABS device that provides full safety for the user under all operating conditions, ensuring the proper operation of the braking system even when the ABS device is failing i.e. , without power supply.

[0031] A further purpose of the invention is to provide an ABS device that results in minimal power consumption for activating the ABS function.

[0032] Summary of the invention

[0033] In view of achieving one or more of the above-mentioned purposes, the invention has as its object an ABS device having all of the features which have been indicated at the beginning of the present description and further characterized in that the switching of said valve unit between its first operating condition and its second operating condition is controlled by a solenoid, which is operatively associated with the movable member of said fluid accumulator and which is configured and arranged so that when said solenoid is energized it causes:

[0034] - a switching of said valve unit from said first operating condition to said second operating condition,

[0035] - and also the application of a force to said movable member of the fluid accumulator, tending to push said movable member towards its starting position, corresponding to a minimum volume of the accumulator chamber.

[0036] According to a preferred feature of the invention, said electronic controller is programmed to supply a variable electric current to said solenoid, such that:

[0037] - when the electronic controller detects a condition in which an ABS function activation is required, the electronic controller is configured to perform these operations:

[0038] - in a first step, the electronic controller supplies a relatively high level of electric current to said solenoid, such that it switches the valve unit from the first operating condition to the second operating function, while pushing the movable member of the fluid accumulator towards to its starting position,

[0039] - in a second subsequent step, the electronic controller supplies a relatively low level of electric current to said solenoid, so that the valve unit is maintained in its second operating condition, while the movable member of the fluid accumulator is free to move away from its starting position so as to cause said decrease in pressure in the connection between said outlet and the actuator cylinder of the brake device (the current supplied to the solenoid is modulated at a level that is a function of the pressure to be obtained, and that corresponds to a given position of the movable member, until the braking is completed),

[0040] - in a third subsequent stage, the electronic controller returns to supplying a relatively high level of electric current to said solenoid, such that the movable member of the fluid accumulator returns to its starting position, while the valve unit remains in its second operating condition (the level of current is modulated to a level that is a function of the pressure to be obtained, which corresponds to a given position of the movable member until braking is completed),

[0041] - in a fourth subsequent stage, after the movable member of the fluid accumulator has returned to its starting position, and once ABS functionality is no longer required, the electronic controller interrupts the power supply to said solenoid, so taht the valve unit returns to its first operating condition, while the movable member of the fluid accumulator remains in its starting position.

[0042] In the second stage mentioned above, the current flowing in the solenoid is reduced in proportion to the force generated by the fluid on the movable member of the fluid accumulator, so as to allow the movable member to move and thus gradually reduce the pressure in the brake caliper, to ensure safe braking

[0043] According to a further preferred feature, said valve unit includes a safety valve configured to connect said outlet with said inlet when the valve unit is in its second operating condition and if, under said condition, the pressure in said outlet tends to become greater than the pressure in said inlet.

[0044] In preferred embodiments of the invention, the said valve unit includes: - a main passage connecting said inlet with said outlet, which is in an open position in the said first operating condition of the valve unit,

[0045] - a first valve interposed in said main passage between said inlet and said outlet and which is in an open position in said first operating condition of the valve unit,

[0046] - a second valve, which controls a connection between said main passage and the fluid accumulator chamber, and which is in a closed position in the said first operating condition of the valve unit, and

[0047] - an actuator element, movable against the action of a spring by energization of said solenoid, so as to simultaneously bring the first valve to a closed position and the second valve to an open position.

[0048] The invention also relates to the method of controlling the ABS device described above.

[0049] This method may also include a fifth step of compensating for any oil leakage from the first valve to the second valve during their switching, by means of a “cleaning” cycle, in which:

[0050] - the user does not brake

[0051] - current is supplied to solenoid to open the second valve,

[0052] - the movable member of the fluid accumulator goes to its starting position, emptying the accumulation chamber,

[0053] - the fluid subsequently flows from the brake caliper line to the brake lever line due to the relief function of the first valve.

[0054] Detailed description of the invention

[0055] Further features and advantages of the invention will result from the following description with reference to the appended drawings, provided as non-limiting examples only, in which:

[0056] - figures 1 , 2 illustrate a schematic of a hydraulic braking system including an ABS device according to the invention in a first operating condition and a second operating condition, respectively,

[0057] - Figures 3, 4 are schematic views of a first embodiment of the ABS device according to the invention in the first operating condition and in the second operating condition, respectively; and

[0058] - Figure 5 is a perspective view of a second embodiment of the ABS device according to the invention, - Figures 6-9 are cross-sectional views of the device in Figure 5 under different operating conditions,

[0059] - figures 10-13 are cross-sectional views of a further embodiment under different operating conditions.

[0060] Referring to Figures 1 , 2, reference numeral 1 generally designates a hydraulic braking system for a bicycle, including a master cylinder 2, associated in any known manner with a bicycle brake lever (not illustrated), an actuator cylinder 3, associated in any known manner with a brake device, typically a disc brake caliper (not illustrated), and an ABS device, indicated schematically as a whole by 4.

[0061] ABS device 4 comprises an inlet 5 hydraulically connected to master cylinder 2 of the brake lever, via a hydraulic line 6, and an outlet 7 hydraulically connected to actuator cylinder 3 of the brake caliper via a hydraulic line 8.

[0062] The ABS device 4 comprises a fluid accumulator 9 having a accumulation chamber 10 defined by a movable member 11 which in the example is a plunger provided with a rod 12. The plunger 11 is movable within a cavity in the body of the fluid accumulator 9 and is normally in a starting position (illustrated in Figure 1 ) corresponding to a minimum volume of the accumulation chamber 10.

[0063] ABS device 4 also includes a valve unit, generally designated by 13, which is electrically operated and switchable between a first operating condition and a second operating condition.

[0064] In the first operating condition of valve unit 13, illustrated in Figure 1 , valve unit 13 connects inlet 5 and outlet 7 with each other, so that, in this condition, the braking system is able to operate normally, allowing the user to activate the brake caliper by acting on the brake lever. Valve unit 13 is normally maintained in the above first operating condition, shown in Figure 1 , by spring means 14.

[0065] The valve unit 13 can be switched by energizing a solenoid 15 (described in more detail below) from the first operating condition illustrated in Figure 1 to the second operating condition illustrated in Figure 2, in which the communication between inlet 5 and outlet 7 is interrupted and the accumulation chamber 10 of the fluid accumulator 9 enters into communication with outlet 7. The power supply of solenoid 15 is controlled by an electronic controller E of the ABS device. The electronic controller E is configured to detect a condition in which an ABS function is required to be activated by receiving a signal S indicative of such a need, from a sensor of any known type with which the bicycle is equipped (e.g., an angular speed sensor of the bicycle's front wheel rotation, or a load sensor on the bicycle's rear wheel axle, or a pressure sensor in the brake caliper actuator cylinder).

[0066] When the electronic controller E receives a signal S indicative of the need to activate the ABS function, the electronic controller E supplies electric current to the solenoid 15, in the manner that will be described in more detail below, so as to cause the valve unit 13 to switch from its first operating condition shown in Figure 1 to its second operating condition shown in Figure 2.

[0067] According to an important feature of the invention, the solenoid 15 which controls the switching of the valve unit 13 is a solenoid which is operatively associated with the movable member 11 of the fluid accumulator 9 and which is configured and arranged so that, when activated, it tends to apply to the movable member 11 of the fluid accumulator 9 a force F tending to keep the movable member 11 in its starting position corresponding to the minimum volume of the accumulation chamber 10.

[0068] Thus, solenoid 15 is able to simultaneously control both the switching of valve unit 13 (since movable member 18 is attracted toward fixed member 152 when the solenoid is active) and a thrust applied to movable member 11 of fluid accumulator 9, tending to push movable member 11 toward its starting position corresponding to the minimum volume of accumulation chamber 10.

[0069] In actual embodiments, as will result in the following, solenoid 15 is mounted coaxially around fluid accumulator 9 in a position where it is also acted upon to cooperate with an actuator member (described in detail below) that controls the operating condition of valve unit 13.

[0070] A pressure sensor P is apt to detect the pressure in the actuator cylinder 3 of the brake caliper and send a signal indicative of the detected pressure to the electronic controller E.

[0071] The operation of the ABS device schematized in Figures 1 , 2 is as follows. During normal use of the bicycle, when the ABS function is not required, solenoid 15 is not supplied with electricity and valve unit 13 is in its first operating condition shown in Figure 1 . In this condition, an action on the brake lever causes fluid transfer from master cylinder 2, through line 6, valve unit 13 and line 8, to actuator cylinder 3 of the brake caliper, which is thus normally activated.

[0072] Spring 14 is configured to be able to counterbalance the hydraulic force generated by the brake lever side pressure even when the user presses at maximum force.

[0073] If the electronic controller E receives a signal S indicative of the need for an ABS function intervention, in a first step, the electronic controller E supplies a relatively high level of electric current to the solenoid 15, so as to switch the valve unit 13 from the first operating condition to the second operating condition, but pushing the movable member 11 of the fluid accumulator 9 to its starting position shown in Figure 1 , despite the fact that the accumulator chamber 9 receives pressurized fluid from the line 8 connected to the actuator cylinder 3 of the brake caliper.

[0074] In a second subsequent step, the electronic controller supplies a relatively low level of electric current to said solenoid (the current can be modulated by gradually decreasing it from high level to low level), such that the valve unit 13 is maintained in its second operating condition illustrated in Figure 2, while the movable member of the fluid accumulator moves from its starting position (as illustrated in Figure 2) as the force due to the pressure of the fluid reaching the chamber 10 exceeds the force applied to the movable member 11 by the solenoid 15. The increase in the volume of chamber 10 causes a decrease in the pressure in line 8 connected to actuator cylinder 3 of the brake caliper, resulting in the ABS effect, which prevents the wheel from locking during braking.

[0075] In this condition, a one-way valve that is part of valve unit 13 provides automatic opening, connecting the downstream line 8 connected to actuator cylinder 3 of the brake caliper with the upstream line 6 connected to actuator cylinder 2 of the lever if, for any reason, the pressure of downstream line 8 tends to exceed the pressure of upstream line 6.

[0076] The electronic controller E, in the phase of activating the ABS function, controls the current supplied to the solenoid 15 in order to establish a certain pressure level in the brake caliper actuator cylinder, solely on the basis of the signal provided by the pressure sensor P, thus without the need to set up a sensor of the position of the movable member of the fluid accumulator.

[0077] In a third subsequent step, the electronic controller E returns to supply a relatively high level of electric current to the solenoid (e.g., the current can be modulated by gradually increasing it from the lowest value to the highest value), such that the movable member 11 of the fluid accumulator 9 returns to its starting position (illustrated in Figure 1 ) as a result of the increase in the force F applied by the solenoid, while the valve unit 13 still remains in its second operating condition illustrated in Figure 2.

[0078] In a fourth subsequent step, after the movable member 11 of fluid accumulator 9 has returned to its starting position, and once ABS functionality is no longer required, the electronic controller E interrupts the power supply to solenoid 15, so that the valve unit returns to its first operating condition illustrated in Figure 1 , while the movable member of fluid accumulator 9 remains in its starting position, illustrated in Figure 1.

[0079] Preferably, a fifth step is also provided to compensate for any fluid leakage from the first valve to the second valve during their switching, by a “cleaning” cycle, in which:

[0080] - the user does not brake,

[0081] - power is supplied to solenoid 15 to open the second valve V2,

[0082] - the movable member 11 of the fluid accumulator 9 goes to its starting position, emptying the accumulation chamber 10,

[0083] - fluid subsequently flows from line 8 of the brake caliper to line 6 of the brake lever due to a relief function of the first valve V1 .

[0084] With reference now to Figures 3, 4, relating to a first concrete example of the implementation of the invention, the parts illustrated in these figures that functionally correspond to the parts illustrated in Figures 1 , 2 are indicated by the same reference number.

[0085] Figure 3 illustrates an example of the ABS device 4 according to the invention, in which the valve unit 13, the fluid accumulator 9 and the solenoid 15 are associated with each other within a common structure.

[0086] Specifically, in that exemplary embodiment, the solenoid 15 is mounted between an inner tubular sleeve 150 and an outer cylindrical shell 151. Arranged within the inner tubular sleeve 150 is a stator body 152 of ferromagnetic material traversed by a central cylindrical cavity 152A within which the plunger stem 12 constituting the movable member 11 of the fluid accumulator 9 is slidingly mounted. Within the tubular sleeve 150 is mounted sliding, in contact with the end of the stem 12 opposite the plunger 11 , a movable anchor 153 of ferromagnetic material, which is kept in contact with the stem 12 by an anti-vibration spring 154.

[0087] Still with reference to Figures 3, 4, the accumulation chamber 10 of the fluid accumulator 9 is defined in a body 16 of the valve 13 assembly. Also defined in body 16 are inlet 5, to be hydraulically connected with master cylinder 2 of the brake lever, outlet 7, to be hydraulically connected with actuator cylinder 3 of the brake caliper, and a main passage 17, connecting inlet 5 with outlet 7.

[0088] Again with reference to Figures 3, 4, body 16 of valve unit 13 incorporates a first valve V1 interposed in main passage 17 and connecting inlet 5 to outlet 7, and a second valve V2 that controls the connection between main passage 17 and accumulator chamber 10 of fluid accumulator 9.

[0089] As will be detailed below, when the ABS device is in the first operating condition shown in Figure 1 , that is, when solenoid 15 is de-energized, valve V1 is in an open condition and valve V2 is in a closed condition.

[0090] Valve unit 13 includes an actuator element 18, which is configured to simultaneously switch valve V1 to the closed condition and valve V2 to the open condition as a result of energizing solenoid 15 against the action of a spring 14. In the concrete example shown in Figure 3, the actuator element 18 is in the form of an annular plate of ferromagnetic material, and the spring 14 is a helical spring interposed axially between the plate 18 and one end of the stator body 152, such that the spring 14 tends to hold the plate 18 against an end face of the body 16 of the valve unit 13 that is facing the stator body 152. As visible in Figure 3 and Figure 4, in the illustrated example, the plate 18 is rigidly connected to two pins S1 , S2, which control the operating condition of valves V1 and V2, respectively. Specifically, in the illustrated example, valve V1 consists of a ball recalled by a spring to a closed condition of the valve seat, and plug S1 is configured to push the ball of valve V1 to an open position in the first operating condition shown in Figure 3, in which solenoid 15 is de-energized. Plug S2 is configured to act as the plug element of valve V2 and is called back by a spring to an open position of valve V2.

[0091] Associated with the valve unit body 13 is the pressure sensor P, which is configured to sense the pressure in the main passage 17.

[0092] The operation of ABS device 4 in the embodiment of Figures 3, 4 is as follows.

[0093] When solenoid 15 is de-energized, ABS device 4 is in the first operating condition, illustrated in Figure 3, corresponding to the condition shown schematically in Figure 1. In that condition, spring 14 keeps plate 18 in the position in contact with one face of body 16 of valve unit 13, so that pin S1 keeps valve V1 open, while pin S2 is in the closed position of valve V2. In this condition, therefore, ABS device 4 puts inlet 5 in communication with outlet 7 through main passage 17, so the braking system is able to operate normally. Whenever there is an action on the brake lever, pressurized fluid is transferred from the master cylinder 2 of the brake lever to the actuator cylinder 3 of the brake caliper (Figure 1 ), passing through the main passage 17 of the ABS device 4. in this condition, just because the second valve V2 is closed, it is ensured that the movable member 11 remains in its rest position (position corresponding to the minimum volume of the accumulation chamber 10) without any energy consumption, which is a fundamental advantage of the present invention.

[0094] If the electronic controller E of the ABS device receives a signal S (Figures 1 , 2) indicative of the need for an ABS effect trip, the electronic controller E supplies a relatively high level of electric current to the solenoid, sufficient to achieve two effects:

[0095] - the plate 18, which is made of ferromagnetic material, is drawn against the adjacent end of the stator body 152 by the magnetic field generated by the solenoid 15, so that the plug S1 moves to the position corresponding to the closing of the valve V1 and the plug S2 moves to the position corresponding to the opening of the valve V2. This condition is illustrated in Figure 4;

[0096] - at the same time, the magnetic field generated by the solenoid 15 causes the movable anchor 153 to push against the stem 12 of the movable member 11 of the fluid accumulator 9, in the direction tending to keep the movable member 11 in the position corresponding to the minimum volume of the accumulation chamber 10.

[0097] Once the two valves V1 , V2 have been switched to the closed condition and the open condition, respectively, as shown in Figure 4, the electronic controller E decreases the level of electric current supplied to the solenoid 15 to a low level where the force F applied by the moving anchor 153 to the stem 12 is not sufficient to counteract a movement of the movable member 11 of the fluid accumulator in the direction corresponding to an increase in the volume of the accumulation chamber 10 (toward the right with reference to the figures), as a result of the arrival in the accumulator chamber 10 of fluid from the downstream line 8 of the brake caliper actuator cylinder, through valve V2. The pressure in the valley line 8 communicating with the caliper actuator cylinder 3 (Figures 1 , 2) decreases, thus achieving the ABS effect. Preferably, the transition of the electrical supply current to the solenoid 15 from the high value to the low value is made through a gradual decrease. This also realizes the advantage of allowing the electronic controller E to be programmed to realize the desired ABS effect by modulating the electrical supply current of solenoid 15 in any desired way.

[0098] Once the need for the ABS effect ceases to exist, the electronic controller arranges to raise the level of the current supplied to solenoid 15, preferably progressively, until it returns to a relatively high current level, so as to increase the force F applied by the moving anchor 153 and push the movable member 11 back to its starting position, corresponding to the minimum volume of accumulation chamber 10. Once this condition is reached, solenoid 15 is completely de-energized, which allows plate 18 to return to its rest position illustrated in Figure 3, under the thrust of spring 14, so as to switch valve V1 back to the open condition and valve V2 back to the closed condition.

[0099] In the operating condition of activating the ABS effect (figure 4), if the pressure in the main passage 17 communicating with the downstream line 8 on the brake caliper side tends to become greater than the pressure in the upstream line 6 on the brake lever side, valve V1 acts as a safety valve in that it opens due to the effect of the aforementioned pressure differential.

[0100] Figures 5-9 refer to a second concrete example of ABS device implementation according to the invention. In these figures, parts common to or equivalent to those shown in Figures 1 , 2 and 3, 4 are shown with the same references.

[0101] Also in the implementation form of Figures 5-9, the solenoid 15 is received between an inner tubular sleeve 150 and an outer cylindrical shell 151. Again, inside the cylindrical sleeve 151 is arranged a stator body 152 traversed by a central cylindrical cavity 152A within which the stem 12 of the plunger constituting the movable member 11 of the fluid accumulator 9 is slidingly mounted. Again, inside the tubular sleeve 150 is arranged a movable anchor 153 in the form of a cylindrical body, which is held against the end of the stem 12 opposite the plunger 11 by an anti-vibration spring 154.

[0102] Also in the example of Figures 5-9, body 16 of valve unit 13 defines inlet 5 that can be hydraulically connected with the master cylinder of the brake lever, outlet 7 to be hydraulically connected with the actuator cylinder of the brake caliper, and a main passage 17 that connects inlet 5 with outlet 7. Again, the two valves V1 , V2 which, in the de-energized condition of the solenoid, are in an open condition and a closed condition, respectively, are integrated in the body 16 of the valve unit 13. Again, in its open condition, valve V1 leaves free communication through the main passage 17 between inlet 5 and outlet 7. Again, in its closed condition, valve V2 prevents a communication of main passage 17, on one side communicating with outlet 7, with accumulation chamber 10 (best seen in Figure 7, which illustrates the second operating condition of the ABS device) of fluid accumulator 9.

[0103] The main difference of the example in Figures 5-9 from the example in Figures 3, 4 lies in the fact that, in the case of the example in Figures 5- 9, the two valves V1 , V2 are aligned along the same axis, instead of being arranged along two axes that are parallel to each other and spaced apart.

[0104] In the example of Figures 5-9, the actuator element 18 that causes the valves V1 , V2 to switch to the closed condition and the open condition, respectively, as a result of energizing the solenoid 15, is an annular metal body, made of ferromagnetic material, mounted sliding within the outer cylindrical casing 151 of the solenoid. The annular body 18 has a central cylindrical cavity 18A traversed by the stem 12 of the movable member 11 of the fluid accumulator and has an outer annular portion driven by a series of coil springs 14 in contact with the adjacent face of the body 16 of the valve unit 13. The annular body constituting the actuator element 18 is rigidly connected to an axial pin S2 that controls the plug (in the example, a ball) of the second valve V2. The stem 12 of the fluid accumulator movable member 9 has a centrally grooved portion 12A to avoid interference with pin S2, so the movements of pin S2 and with it of actuator element 18 and the movements of stem 12 and movable member 11 of the fluid accumulator are independent of each other. For the same reason, the plunger constituting movable member 11 of fluid accumulator 9, which in this case consists of a cylindrical body rigidly connected to the centrally grooved portion of stem 12, has an axial cavity for the passage of pin S2. The cylindrical body constituting the movable body 11 of the fluid accumulator 9 is provided on its outer surface with sealing rings cooperating with the cylindrical wall of the body cavity 16 in which the movable body 11 is mounted sliding, and at least one additional inner sealing ring cooperating with the pin S2.

[0105] In a preferred example, the S2 plug is rigidly connected to a ball plug of the second valve V2. In addition, a plug S1 is operationally interposed between the ball poppet of valve V2 and a ball poppet of valve V1 , which is recalled to a closed position by a respective coil spring.

[0106] As shown in Figures 6-9, in this implementation example, valves V1 , V2 are received within coaxial cavities formed in body 16 of valve unit 13 from two opposite faces of body 16. These cavities communicate with a cavity formed in the body 16 orthogonally to the axis of alignment of the valves V1 , V2, and defining a portion of the main passage 17 connecting the outlet 7 with the inlet. In the specific embodiment illustrated here, outlet 7 is defined by a connecting element 70, rigidly connected to the body 16 of the valve unit 13 and within which a cylindrical body 71 having an axial bore defining a portion of the main passage 17, which communicates with a radial bore flowing into a circumferential throat of the body 71 , defining an annular chamber communicating with outlet 7, is tightly mounted.

[0107] Similar to the solution in Figures 3, 4, the body 16 is also associated with the pressure sensor P, configured to detect pressure in the main passage 17.

[0108] The operation of the ABS device according to the embodiment in Figures 5-8 is quite similar to that shown above with reference to Figures 1 , 2 and 3, 4.

[0109] When solenoid 15 is de-energized, the device is in its first operating condition, illustrated in Figure 6. In this condition, actuator element 18 is held by springs 14 in the position illustrated, against the adjacent face of body 16, whereby pin S2 keeps valve plug V2 in the closed condition of valve V2. Consequently, pin S1 interposed between the valve plugs of valves V2 and V1 keeps the valve plug V1 in its open condition of valve V1 , against the action of the respective spring. In such a situation, therefore, inlet 5 and outlet 7 communicate with each other through main passage 17 and the first valve V1 , while accumulation chamber 10 of fluid accumulator 9 is isolated with respect to said main passage 17.

[0110] When the electronic controller E (see Figures 1 , 2) detects the need for the intervention of the ABS function, the electronic controller energizes the solenoid 15 at a relatively high current level so as to achieve the displacement of the actuator element 18 to its operating position illustrated in Figure 7, against the action of the springs 14 and at the same time the application of a force F by the movable anchor 153 against the stem 12 of the movable member 11 of the fluid accumulator 9, tending to keep the movable member 11 in the position corresponding to the minimum volume of the accumulation chamber 10. In such a condition, illustrated in Figure 7, the displacement of the actuator element 18 results in the displacement (to the left with reference to the figures) of the plug S2, resulting in the opening of the valve V2 and a displacement of the plug S1 , resulting in the closing of the valve V1 , the ball poppet of which is pushed into the closed position by the respective coil spring. Under this operating condition, the side of the main passage 17 communicating with outlet 7 enters into communication, via valve V2, with accumulation chamber 10. However, the movable member 11 of the fluid accumulator 9 is unable to move away from its starting position, because the solenoid energized at a relatively high current level applies sufficient force to the stem 12 of the movable member 11 , via the movable anchor 153, to counteract such movement.

[0111] Once the operating condition illustrated in Figure 7 has been achieved, that is, once valves V1 , V2 have been switched to the closed and open conditions, respectively, the electronic controller can bring the solenoid supply current 15 to a low level, preferably by a gradual decrease such that the actuator element 18 remains in the operating position shown in Figure 7, while the moving anchor 153 exerts a lower force against the stem 12, so that the movable member 11 is able to move away from its starting position, thus causing an increase in the volume of the accumulation chamber 10 (see Figure 8) which results in the ABS effect. In such a condition, if for any reason the pressure on the brake caliper side tends to become greater than the pressure on the brake lever side, valve V1 opens automatically, acting as a safety valve, so as to discharge the excess pressure from the line connected to outlet 7 to the line connected to inlet 5.

[0112] When the need for the ABS effect ceases to exist, the electronic controller again increases the current of the solenoid supply 15, preferably in a progressive manner, to a high level sufficient to cause the moving anchor 153 to push the stem 12 and with it the movable member 11 back to the starting position, corresponding to the minimum volume of the accumulation chamber. Once this condition is reached, the electronic controller E de-energizes the solenoid 15 so as to return the ABS device 4 to the starting condition shown in Figure 6.

[0113] Figures 10-13 illustrate a further form of actuation, which differs from the form of actuation in Figures 5-9 by a different arrangement of the fluid accumulator. In those figures, the common parts are shown with the same reference numbers.

[0114] In the case of the variant of Figures 10-13, there is rigidly connected to the stator body 152 a stem 120 (which is thus stationary like the stator body 152) carrying a plunger (also stationary) 110 that is arranged with sliding engagement within an internal cavity 153A of the movable anchor 153. The stationary plunger 110 thus defines, within cavity 153A, a chamber whose volume varies as the movable anchor 153 moves relative to the stationary plunger 110, to serve as the accumulation chamber 10 of fluid accumulator 9. The fluid accumulator 9 therefore consists, in this variant, of the movable anchor 153 itself, which is controlled by the solenoid 15. T heaccumulation chamber 10 within the movable anchor 153 communicates with the valve unit 13 through passages formed in the stem 120 of the stator body 152 and in the actuator member 18. In the example shown, the actuator member 18 has an annular body, as in Figures 5-9, with a tubular stem 180 terminating in a head 181 mounted sliding within an axial cavity 160 of the body 16 of the valve unit 13.

[0115] The operation of the actuation form of Figures 10-13 is quite similar to that of the actuation form of Figures 5-9.

[0116] Figure 10 illustrates the normal condition with ABS inactive, in which valve V1 is open to allow communication between inlet 5 and outlet 7, while valve V2 is closed so that chamber 10 of fluid accumulator 9 does not communicate with main passage 17.

[0117] Figure 11 illustrates the initial condition of solenoid 15 tripping at the maximum supply current, which causes valves V1 , V2 to switch as a result of the movement of actuator member 18.

[0118] Figure 12 illustrates the current modulation phase of solenoid 15, which causes the movable anchor 153 to move. Resulting in an increase in the volume of the accumulation chamber 10.

[0119] Figure 13 shows the condition where, for example during the modulation phase, the current supply to solenoid 15 is interrupted, so that the actuating member is returned by springs 14 to the rest position where it closes valve V2 and opens valve V1 , allowing normal braking.

[0120] It should be noted that in all the forms of actuation shown above, spring 154 is a spring with a relatively low load, which has the sole function of keeping the moving anchor 153 against stem 12, preventing vibration of the anchor 153. In other words, spring 154 is not capable of acting as a return spring for the movable 11 member toward its starting position. This return action, in the ABS device of the present invention, is carried out by the solenoid 15. In other words, the ABS device 4 would be able to operate even if the spring 154 were eliminated.

[0121] It should also be noted that the recall action of the solenoid 15 is not preparatory to ensuring a safe condition, because it is the movable member 18 that, due to the effect of the safety springs 14, in the absence of power supply brings the system back to the starting condition (line 6 on the brake lever side in communication with line 8 on the brake caliper side) regardless of the position of the movable member 152A. Therefore, in all of the forms of actuation described above, the spring 14(s) associated with actuator element 18 is configured such that, in the absence of an energization of solenoid 15, actuator element 18 remains in a position where it keeps the first valve V1 open and the second valve V2 closed, even in the presence of a pressure increase in the main passage 17 brought about by braking, as long as there is no need for an intervention of the ABS function.

[0122] In the example illustrated in Figures 5-9, the spring 154 is interposed between an end of the movable anchor 153 protruding outside the device 4 and a wall (not visible in the drawings) made from a plastic cover whose sole function is to provide a reaction for the spring 154 and to ensure sealing.

[0123] Naturally, while the principle of the invention remains the same, the details of construction and the embodiments may vary widely from what has been described and illustrated herein purely by way of example, without departing from the scope of the present invention as defined in the appended claims.

Claims

CLAIMS1. ABS device for a hydraulic braking system of a cycle or motorcycle or a 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,- a fluid accumulator (9) having an accumulation chamber (10) defined by a movable member (11 ) within a cavity, said movable member (11 ) being normally in a starting position corresponding to a minimum volume of the accumulation chamber (10),- an electrically operated valve unit (13) switchable between:- a first operating condition, in which said inlet (5) and said outlet (7) communicate with each other while said accumulation chamber (10) of the fluid accumulator (9) is isolated, and- a second operating condition in which the 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 controller (E) configured to detect a condition in which an activation of an ABS function is required, and which, in such a condition, is further configured to cause a switching of said valve unit (13) from the first operating condition to the second operating condition and to enable a movement of the movable member (11 ) of said fluid accumulator (9) in a direction corresponding to an increase in the volume of the accumulation chamber (10), so as to cause a decrease in the pressure in the line connecting said outlet (7) with the actuator cylinder (3) of said brake device, said ABS device being characterized in that the switching of said valve unit (13) between the first operating condition and the second operating condition is controlled by a solenoid (15) which is operatively associated with the movable member (11 ) of said fluid accumulator (9) and which is configured and arranged so that when said solenoid (15) is energized it causes:- a switching of said valve unit (13) from the first operating conditionto the second operating condition,- and also the application of a force (F) to said movable member (11 ) of the fluid accumulator (9) tending to push the movable member (11 ) towards its starting position corresponding to a minimum volume of the accumulation chamber (10).

2. ABS device according to claim 1 , characterized in that said electronic controller (E) is programmed to supply a variable electric current to said solenoid (15) such that:- when the electronic controller (E) detects a condition in which activation of an ABS function is required, the electronic controller (E) is configured to perform these operations:- in a first step, the electronic controller (E) supplies a relatively high level of electric current to said solenoid (15), so as to switch the valve unit (13) from the first operating condition to the second operating condition, while pushing the movable member (11 ) of the fluid accumulator (9) towards its starting position,- in a second subsequent step, the electronic controller (E) supplies a relatively low level of electric current to said solenoid (15), so that the valve unit (13) is maintained in its second operating condition, while the movable member (11 ) of the fluid accumulator (9) is free to move away from its starting position, so as to cause said pressure decrease in the line connecting said outlet (7) with the actuator cylinder (3) of the brake device,- in a third subsequent step, the electronic controller (E) returns to supply a relatively high level of electric current to said solenoid (15), so that the movable member (11 ) of the fluid accumulator (9) returns to its starting position, while the valve unit (13) remains in its second operating condition,- in a fourth subsequent step, after the movable member (11 ) of the fluid accumulator (9) has returned to its starting position, and once the ABS function is no longer needed, the electronic controller (E) interrupts the power supply to said solenoid (15), so that the valve unit (13) returns to its first operating condition while the movable member (11 ) of the fluid accumulator (9) remains in its starting position.

3. An ABS device according to claim 1 , characterized in that itincludes a pressure sensor (P) configured and arranged to sense the pressure in the actuator cylinder (3) of the brake device, and in that said electronic controller (E), in the phase of activating the ABS function, controls the current supplied to said solenoid (15) solely on the basis of a signal provided by said pressure sensor (P), without the need to arrange a sensor of the position of the movable member (11 ) of the fluid accumulator (9).

4. ABS device according to claim 1 , characterized in that said valve unit (13) includes a safety valve configured to put in communication said outlet (7) with said inlet (5), when said valve unit (13) is in its second operating condition and if, in this condition, the pressure at said outlet (7) tends to become greater than the pressure at said inlet (5).

5. An ABS device according to claim 1 , characterized in that said valve unit (13) includes:- a main passage (17) connecting said inlet (5) with said outlet (7),- a first valve (V1 ) interposed in said main passage (17) between said inlet (5) and said outlet (7) and which is in an open position in said first operating condition of the valve unit (13),- a second valve (V2) controlling a connection between said main passage (17) and the accumulation chamber (10) of the fluid accumulator (9), and which is in a closed position in the said first operating condition of the valve unit (13)- an actuator element (18), movable against the action of a spring (14) by energization of said solenoid (15) so as to simultaneously bring the first valve (V1 ) to a closed position and the second valve (V2) to an open position.

6. An ABS device according to claim 1 , characterized in that the spring (14) associated with the actuator element (18) is configured such that, in the absence of an energization of the solenoid (15), the actuator element (18) remains in a position in which it keeps the first valve (V1 ) open and the second valve (V2) closed, even in the presence of a pressure increase in said main passage (17) caused by a braking maneuver, as long as there is no need for an intervention of the ABS function.

7. ABS device according to claim 5, characterized in that:- said solenoid (15) is mounted between an inner tubular sleeve (150) and an outer cylindrical casing (151 ),- within said inner tubular sleeve (150) there are arranged, axially aligned, a stator body (152), and a movable anchor (153) which is slidably mounted within said inner tubular sleeve (150) and connected to the movable member (11 ) of the fluid accumulator (9), so that upon energization of the solenoid (15) the movable anchor (153) applies a force (F) to the movable member (11 ) in the direction of a decrease of the volume of the accumulator chamber (10).

8. An ABS device according to claim 5, characterized in that the stator body (152) has a central cylindrical cavity (152A) within which a stem (12) of the movable member (11 ) of the fluid accumulator (9) is slidably mounted.

9. An ABS device according to claim 5, characterized in that to the stator body (152) there is rigidly connected a stem carrying a plunger (110) which is arranged, with sliding engagement, within an inner cavity (153A) of the movable anchor (153), so as to define a variable volume chamber within the movable anchor (153), which serves as the accumulation chamber (10) of the fluid accumulator (9).

10. ABS device according to claim 5, characterized in that the accumulation chamber (10) within the movable anchor (153) communicates with said valve unit (13) via passages formed within said stem of the stator body (152) and within said actuator member (18).

11. ABS device according to claim 7, characterized in that:- said valve unit (13) comprises a valve body (16) rigidly connected to said outer cylindrical casing (151 ) of said solenoid (15),- said actuator member (18) is an annular member interposed axially between one end of said stator body (152) and the body (16) of said valve unit (13), said actuator member (18) being pushed by one or more springs(14) towards a first operating position in which it holds said first valve (V1 ) open and said second valve (V2) closed and being adapted to be pushed against a facing end of said stator body (152) as a result of energizing said solenoid (15), so as to cause a closing of said first valve (V1 ) and an opening of said second valve (V2).

12. An ABS device according to claim 11 , characterized in that said actuator element (18) controls said first valve (V1 ) and said second valve (V2) by means of needles (S1 , S2) parallel to, and spaced apart from, each other.

13. ABS device according to claim 11 , characterized in that said actuator element (18) controls said first valve (V1 ) and said second valve (V2) by means of needles (S1 , S2) arranged aligned with each other, on the extension of each other.

14. A method for controlling an ABS function in a hydraulic braking system of a cycle or motorcycle, particularly a bicycle, in which there is arranged:- 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,- a fluid accumulator (9) having an accumulation chamber (10) defined by a movable member (11 ) within a cavity, said movable member (11 ) being normally in a starting position corresponding to a minimum volume of the accumulation chamber (10),- an electrically operated valve unit (13), switchable between:- a first operating condition, in which said inlet (5) and said outlet (7) communicate with each other, while said accumulation chamber (10) of the fluid accumulator (9) is isolated, and- a second operating condition 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 anelectronic controller (E), a condition in which an activation of an ABS function is required and causing, in said condition, a switching of said valve unit (13) from the first operating condition to the second operating condition, and further allowing a movement of the movable member (11 ) of said fluid accumulator (9) in a direction corresponding to an increase in the volume of said accumulation chamber (11 ), so as to cause a decrease in the pressure in the line connecting said outlet (7) with the actuator cylinder (3) of said brake device, said method being characterized by the fact that the switching of said valve unit (13) between the first operating condition and the second operating condition is controlled by a solenoid (15) which is operatively associated with the movable member (11 ) of the fluid accumulator (9) and which is configured and arranged in such a way that when said solenoid (15) is energized it causes:- a switching of said valve unit (13) from the first operating condition to the second operating condition,- and also the application of a force (F) to said movable member (11 ) of the fluid accumulator (9) tending to push the movable member (11 ) to its starting position, corresponding to a minimum volume of the accumulation chamber (10).

15. A method according to claim 10, characterized in that it includes supplying a variable electric current to said solenoid (15), via the electronic controller (E), such that:- when the electronic controller (E) detects a condition in which activation of an ABS function is required, the electronic controller (E) is configured to perform these operations:- in a first step, the electronic controller supplies a relatively high level of electric current to said solenoid (15), so as to switch the valve unit (13) from the first operating condition to the second operating collision, while pushing the movable member (11 ) of the fluid accumulator (9) towards its starting position,- in a second subsequent step, the electronic controller (E) supplies a relatively low level of electric current to said solenoid (15), so that the valve unit (13) is maintained in its second operating condition, while the movablemember (11 ) of the fluid accumulator (9) is free to move away from its starting position, so as to cause said pressure decrease in the line connecting said outlet (7) with the actuator cylinder (3) of the brake device,- in a third subsequent step, the electronic controller returns to supply a relatively high level of electric current to said solenoid (15), so that the movable member (11 ) of the fluid accumulator (9) returns to its starting position, while the valve unit (13) remains in its second operating condition,- in a fourth subsequent step, after the movable member of the fluid accumulator has returned to its starting position, and once the ABS function is no longer needed, the electronic controller (E) interrupts the power supply to said solenoid, so that the valve unit (13) returns to its first operating condition, while the movable member (11 ) of the fluid accumulator (9) remains in its starting position.

16. Method according to claim 11 , characterized in that it includes a fifth step 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,- current is supplied to the solenoid (15) to open the second valve (V2),- the movable member (11 ) of the fluid accumulator (9) goes 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 thanks to a relief function of the first valve (V1 ).

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